turner 2000.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg herrmann et al. 1999.2 pg09.jpg pg10.jpg pg11.jpg pg12.jpg sears 2000.3 pg14.jpg pg15.jpg pg16.jpg pg17.jpg pg18.jpg pg19.jpg chegini-farahini et al. 2000.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg phillips-conroy 2000.6 pg27.jpg pg28.jpg 21 dental anthropology 2018 │ volume 31 │ issue 01 frank l’engle williams1,* 1department of anthropology, georgia state university, atlanta, ga 30303, usa *correspondence to: dr. frank l’engle williams, department of anthropology, georgia state university frankwilliams@gsu.edu the list of authors on the paper, “expression of nonmetric dental traits in western european neanderthals” published in dental anthropology, volume 30, issue 01, 3–15 (2017) should be changed to include marie-antoinette de lumley and gaël becam. frank l’engle williams and gaël becam should both be listed as corresponding authors. the authors and affiliations of this publication should appear as listed here. expression of nonmetric dental traits in western european neanderthals frank l’engle williams1,* rebecca l. george2, marie-antoinette de lumley3,4, gaël becam3,* 1department of anthropology, georgia state university, atlanta, ga 30303, usa 2 department of anthropology, university of nevada, reno, nv 89557, usa 3 umr 7194 cnrs, hnhp, mnhn/upvd/cerp de tautavel, france 4 institut de paléontologie humaine, paris, france *correspondence to: dr. frank l’engle williams, department of anthropology, georgia state university frankwilliams@gsu.edu dr. gaël becam, umr 7194 cnrs, hnhp, mnhn/upvd/cerp de tautavel, france gael.becam@cerptautavel.com erratum expression of nonmetric dental traits in western european neanderthals [dental anthropology, 30, 3–15 (2017)] henderson 2007.5 24 teeth, 2nd edition. by simon hillson, 2005. cambridge university press, cambridge. isbn: 0-521-54549-8 as hillson himself says, “one of the striking things about returning to the text almost 20 years later is how few of the fundamentals have in fact changed.” the revised and updated edition of his 1986 classic teeth, however, demonstrates that things can be improved upon. teeth, in the cambridge manuals in archaeology series, provides material on field techniques and methodology combined with current and relevant archaeological examples. teeth are a very common aspect of the archaeological assemblage and can provide extraordinary information on the health and diet of paleocommunties, and hillson brings all these aspects together in a comprehensive manual on the study of teeth. the improvements and updates to this classic are not dramatic, but slight shifts in emphasis and description of recent technological advances makes this second edition a valuable manual for any practitioner of anthropology, paleontology or zoology. the book opens with a lengthy and comprehensive description of tooth form in mammals, intended as a reference manual for identification of teeth in an archaeological context. it is in this section that the bulk of the revisions are evident. while the first edition was wide-ranging, hillson has more than doubled the genera of mammals described and illustrated from 150 to 325, representing the entire holarctic region. one of the most striking changes is the introduction of computer graphics for all the illustrations, teeth has now entered the digital age. this was a labor intensive process for hillson, but the resulting illustrations are legible and highly informative. the level of detail is impressive, greatly aiding in field identification. to offset these additions, hillson has deemphasized human dentition in this edition, setting the tone for what is truly a mammalian tooth book. these are excellent changes, widening the readership and the utility of the book as a field manual. however, with the exclusion of reptiles, amphibians and fish from the book, many of which have teeth, one could argue that the book should be titled mammal teeth. for those with interests primarily in the human tooth, hillson’s (1996) dental anthropology is a wonderful supplemental resource. while the remaining chapters of the book are not as dramatically restructured as the first, hillson has carefully reviewed his earlier work, updating and correcting as necessary. one such example is in the “dental tissues” section (previously “dental microstructure”) which now includes a new section on the chemistry and physics of dental tissue analysis in archaeology. this includes a clear and informative description of the uses of isotopic analysis in dietary reconstruction that have been developed since the first edition came out in 1986 and the role of dentine in dna preservation and analysis. the section has been further updated with a new discussion on methods of dental development reconstruction in hominids and advances in dental preparation techniques including proper use of new camera and scanner technology. the section on “teeth and age” has been updated with more recent studies on dental microwear and its utility in comparing extant and extinct animal behaviors such as diet and life history. this section also includes a new discussion on the genetics, development and morphology of teeth. the first edition devoted significant space to a discussion of tooth size and human evolution. this topic has been dramatically edited and abbreviated in the second edition. in keeping with hillson’s current emphasis on mammals in general rather than humans specifically, discussion of tooth size in human evolution is limited to a few paragraphs on dental reduction through time. even in a field that has not changed significantly since its first printing, the previous edition of teeth is out of date, and was in need of revision. discussion of the origin and evolution of teeth would have been a nice topic to include. however, in a book intended as a practical manual for researchers in many disciplines, it is not a glaring omission. as we all discovered in our use of the first edition, hillson’s teeth is an essential and comprehensive reference manual for all archeologists and paleontologists. this second edition is an excellent update of a reliable and invaluable resource. emily h. henderson [was guthrie] department of anthropology university of oregon book review guatelli-steinberg 2002.6 28 29 perspectives in human biology, volume 4(3): dento-facial variation in perspective. edited by grant townsend and jules kieser. series editor: charles oxnard. centre for human biology, department of anatomy and human biology, university of western australia (paperback), 1999. 172 pp. isbn: 0-86422-934-8. dento-facial variation in perspective consists of 20 peer-reviewed articles based on presentations made at the joint conference of the australian society for human biology (ashb) and the commission of human ecology of the international union of anthropological and ethnological sciences (iuaes) held in adelaide in 1997. these concise papers, incorporating state of the art technology and powerful statistical models, are organized around four central themes: the influences of genes and environment on dento-facial variation; dental wear; dento-facial variation across human populations; and the use of new imaging techniques in morphometric analyses. unifying the contributions to this volume is the useful theoretical perspective of the dento-facial complex as a functional, dynamic system. john mayhall’s keynote address focuses on the problem of using dental complexes to understand population affinities in the absence of a firm understanding of the interaction of genetic and environmental influences on variation in dental morphology. mayhall’s address is a lead-in to several papers dealing with the interaction of genetic and environmental influences on dento-facial variation. authors dempsey, townsend, and martin demonstrate the effectiveness of structural equation modeling to determining the genetic basis of crown size. among other advantages, this method improves on traditional approaches by separating common (or family) environments from genetic factors. of all the permanent teeth examined, the canine and first premolar appear to be most strongly influenced by nonadditive genetic effects while maxillary first molars are most strongly effected by common environment. in their paper, pinkerton and colleagues find that concordance for the carabelli trait is higher in monozygous (mz) as opposed to dizygous (dz) australian twins, reflecting the strong influence of genetic factors on this trait. thomas’s and townsend’s study on interdental spacing in the primary dentition again compares mz and dz australian twins, finding higher concordance of spacing type in mz twins. the australian twins participating in these studies of dento-facial growth were examined for concordance of handedness by dempsey et al., who found no association between handedness and zygosity. while this study is well-designed and interesting, it is not clear why the editors chose to include it in a volume devoted to the subject of dento-facial variation. dento-facial asymmetry is the subject of papers by townsend, dempsey, and richards (asymmetry in the deciduous dentition) and winning, brown, and townsend (human facial asymmetry). in the first of these papers, the authors find no evidence for greater asymmetry in the deciduous teeth of twins relative to singletons, even though it might be supposed that twins compete for nutrition during gestation, experiencing more stressful intrauterine environments than singletons. in the second of these papers, facial asymmetry is found to exhibit extensive individual variability during growth, but there is no overall trend for changes in facial asymmetry with increasing age. genetic abnormalities can reveal important aspects of dental development, as is shown in papers by narayanan, smith, and townsend (cleft lip and palate) and townsend and alvesalo (klinefelter’s syndrome). the authors of the first paper find that fluctuating dental asymmetry is not only elevated in the region of the cleft but also in other regions of the dentition, indicating both local and systemic developmental disruption. the authors of the second paper report greater intercupsal dimensions in the premolars of 47,xxy individuals relative to normal controls, consistent with alvesalo’s previous research demonstrating the influence of the x chromosome on enamel thickness. the next group of papers examines dental wear as affected by craniofacial morphology, tooth-grinding, diet, and culture. authors richards et al. find significant relationships between tooth wear patterns and craniofacial morphology in three australian populations. kaidonis, townsend, and richards show that dental microwear not only results from diet and culture but from tooth-grinding, while springbett et al. find, in their study of australian caucasians and aboriginals, that wear processes differ between the two groups, reflecting cultural and dietary differences. five papers documenting dento-facial variation across populations include studies of cook islanders, south pacific peoples, mioriori, maori, chinese, and caucasians, substantially broadening the perspective of this volume, which, until this point, relies heavily on australian populations. kageyama, mayhall, and townsend use moiré contourography and digital image analysis to study three-dimensional occlusal form in the dentition of australian aborigines. kondo and colleagues find sex differences in the talonid dimensions but not in the trigonid dimensions of cook islanders’ mandibular molars, perhaps reflecting the fact that the talonid forms later in development than the trigonid. in their paper, aboshi et al. find that fijians are less like kirbatians and western samoans, who are more like each other, in the size and shape of their dental arches. an interesting paper by kieser and colleagues examines the relationship between basicranial flexion and glenoidal depth in moriori, maoiri, indians, and caucasians finding that the glenoidal fossa deepens as the basicranial angle decreases. data derived from a ct scan of sts 5 (a. africanus) conforms to this 30 31 trend. the authors believe that the vulnerability of the tmj to dysfunction could be related to the deepening of the glenoid in hominid evolution, in turn a result of the progressive increase in cranial flexion. this cross-cultural section concludes with tasman brown’s paper on providing standards for soft tissue profiles of caucasians and chinese for use in clinical settings. the last three papers of this volume concentrate on the use of new imaging techniques to analyze craniofacial structures. while these papers are of clinical relevance, the techniques described will certainly be of interest to dental anthropologists. chintakanon et al. show that magnetic resonance imaging is a highly effective method of describing variation in tmj morphology. netherway and colleagues use computer tomography for characterizing the human craniofacial skeleton in three dimensions, and abbott et al. use computer tomography to demonstrate that intracranial volume is not smaller than normal in subjects with non-syndromal craniosynostosis while it is significantly larger than normal in those with syndromal craniosynostosis. overall, this volume in the perspectives series coalesces important recent research on the dento-facial complex, with emphasis on the interaction of genes and environment. while many of the studies involve research on australian populations, the editors have included studies on other populations as well. this volume applies powerful new statistical methods and imaging techniques to enhance the understanding of gene-environment interactions and the analysis of variation in dento-facial form. owing perhaps to space constraints, some studies have only brief discussions, and this is in one respect unfortunate because the studies themselves are so interesting. however, concise statements of research problems, materials, methods, and results highlight the many significant and illuminating aspects of these studies. debbie guatelli-steinberg department of anthropology 1218 university of oregon eugene, or 97403-1218 please send notifications of upcoming events, programs, research opportunities, and other items of interest to the editor. they will be published on a gratis, space-available basis. be sure to include an (e-mail) address, so we can confirm the information as needed. artaria 2007.3 42 studies in dental anthropology have never been conducted on indonesians even though the area has a rich variety of peoples and cultures (muttaqin, 2007). the variety of populations may provide valuable data regarding human evolution (hillson, 2002), migration patterns (scott and turner, 2000), and for solving forensic cases (brown, 1992), so it is useful to initiate studies in dental anthropology. before a bigger sample is studied, it is useful to know which dental traits to focus on. additionally, the extent of dental wear is useful for estimating an individual’s age, especially in skeletal material (maples and browning, 1994), so this study also assessed the suitability of a reference base of dental wear rates (brothwell, 1965, cited in bass, 1987:287). materials and methods the sample was 14 individuals (12 females, 2 males) from the island of java (indonesia), whose sex and age were known (age range 19 to 26 years). the dental traits examined were shovel shape, incisor winging, tuberculum dentale, interruption groove, canine distal accessory ridge, premolar accessory ridges, premolar odontomes, premolar accessory marginal tubercles, premolar multiple lingual cusps, accessory marginal tubercles, parastyle, cusp 5, cusp 6, dryopithecus y5 pattern, cusp 7, protostylid, deflecting wrinkle, anterior fovea, distal trigonid crest, hypocone, and carabelli’s cusp. dental traits were scored using the descriptions in scott and turner (2000). age estimations from occlusal tooth wear was based on the reference data in brothwell (1965, cited in bass, 1987). short communication: dental trait variation and age determination based on dental wear: a preliminary study of javanese myrtati d. artaria* department of anthropology, universitas airlangga and department of anatomy and histology, medical faculty, universitas airlangga, surabaya, indonesia abstract this preliminary study describes the dental crown morphology of 14 javanese of known sex and age. the purpose was to suggest what dental traits to look for when studying a bigger sample from java. of 21 traits looked for, traits occurring in the sample were shovel shape, winging, tuberculum dentale, interruption groove, canine distal accessory ridge, premolar accessory ridges, premolar accessory marginal tubercles, premolar multiple lingual cusps, cusp 5, cusp 6, y5 pattern, cusp 7, protostylid, deflecting wrinkle, anterior fovea, hypocone, and carrabelli’s cusp. dental wear overestimated actual ages because the observed rate of wear was less than in the reference sample. dental anthropology 2007;20:42-44. results and discussion shovel shape was very common. this is expected given the asian ancestry of the group. even the canine showed a high incidence of shoveling (table 1). incisor winging occurred in 8 of 14 individuals (57%). very high frequencies of winging are usually found in sinodont dentitions. the people of java are labeled sundadont, and these data suggest that sundadont groups may also have quite high frequencies. expression of tuberculum dentale was weak to moderate; only one individual showed a pronounced canine tuberculum dentale. most individuals lacked a tuberculum dentale on their incisors (table 2). an interruption groove on the upper second incisors occurred in half the sample (7/14 cases). table 1. the number of teeth with shovel-shape maxilla mandible i1 i2 c i1 i2 c no shovel 1 1 1 12 12 1 shovel 13 13 13 2 1 13 total 14 14 14 14 13 14 *correspondence to: myrtati d. artaria, department of anthropology, universitas airlangga, jl. airlangga 4-6, surabaya 60286, indonesia e-mail: mdartaria_fisip@unair.ac.id, myrtati@yahoo. co.id 43 canine distal accessory ridge was uncommon, and when it appeared, the expression was not very strong (score 1 to 3) (table 3). premolar accessory ridges appeared mostly in the lower premolars. the occurrence was 1/14 on p1 and 7/14 in the maxilla, while frequncies of 7/14 and 6/14 occurred on the mandibular premolars. three-cusped second molars were found (1/26 m2), but most molars had 3 or 4 main cusps (table 4). carabelli’s trait complex was expressed in half of the cases. however, the expression was in the form of the most subtle expression (a). the expression of several dental traits is summarized in table 5. anterior fovea was expressed in most cases. a second trait that was expressed quite often (8 instances) was lower premolar multiple lingual cusps. dental traits not found in the sample were accessory marginal tubercles, parastyle, and odontome. occlusal dental wear was less severe than in the reference data (brothwell, 1965, cited in bass, 1987). it would be logical to predict that most teeth in modern humans have less dental wear due to the softer, cooked material eaten, compared to their predecessors. however, modern humans may exhibit tooth abrasion if brushing with an abrasive toothpaste (hillson, 2002). the finding of little dental wear in these javanese compared to the reference sample emphasizes variations in rates among populations, based on tooth cleaning practices, nature of the diet, and cultural practices related to utilizing teeth as tools. we used brothwell’s occlusal wear rates that were derived from british archeological material. the present results show that dental wear reference data should be used cautiously, taking into account the origin of the individual being assessed. it seems that the cultural practices and habits of contemporary javanese do not cause as much dental table 2. the occurrence of tuberculum dentale i1 i2 c no tuberculum dentale 13 12 1 weak 0 1 4 moderate 1 1 8 pronounced 0 0 1 totals 14 14 14 table 3. the occurrence of canine distal accessory ridge 0 1 2 3 4 5 upper 9 1 3 1 0 0 lower 11 1 2 0 0 0 table 4. size gradations of the hypocone right side left side molar 0 1 2 3 4 5 0 1 2 3 4 5 m1 0 0 0 1 11 1 0 0 0 1 13 0 m2 1 0 2 9 0 0 2 0 0 11 1 0 wear as from harder food material eaten by more ancient humans. conclusions based on the dental traits, most (6 out of 7) of the dental characteristics of southeast asian people (scott and turner, 2000) have been found in the sample. besides these seven dental traits, tuberculum dentale, canine distal accessory ridge, premolar accessory ridges, premolar multiple lingual cusps, protostylid, and anterior fovea were also found in the sample. further research on this area should be done with larger sample sizes, and the traits looked for need not be limited to the dental traits indicated as the characteristic of southeast asian people. dental wear in this sample indicated older age of individuals compared to the real ages because of slow table 5. the occurrence of several dental traits frequency dental trait (individuals) odontome 0 premolar accessory marginal tubercle 3 lower premolar multiple lingual cusps 8 accessory marginal tubercles 0 parastyle 0 cusp 5 1 cusp 6 3 y-5 pattern 1 cusp 7 1 protostylid 2 deflecting wrinkle 1 anterior fovea 13 distal trigonid crest 0 javanese dental morphology 44 wear rates, so aging an individual using dental wear reference data should be done cautiously. however, because of the small sample size, more people should be included in the future study. acknowledgements my gratitude to all the students that have been willing to give their dental impressions. my greatest appreciation to susy kristiani, drg., mkes who have given her time and suggestions for the techniques in making dental casts. references cited bass wm. 1987. human osteology: a laboratory and field manual, 3rd edition. columbia: missouri archaeological society, inc. brown ka. 1992. comparative bite marks: differential diagnosis. in: clark dh. practical forensic odontology. london: butterworth-heinemann ltd. hillson s. 2002. dental anthropology. cambridge: cambridge university press. maples wr, browning m. 1994. death in 10,000 fragments. in: maples wr and browning m, editors. dead men do tell tales. new york: doubleday. muttaqin t. 2007. indonesian culture and society. online at http://www.budpar.go.id/ filedata/915_152indonesiaculture1.pdf. accessed 21 august 2007. scott gr, turner cg ii. 2000. the anthropology of modern human teeth. cambridge: cambridge university press. m.d. artaria lee et al. 2003.3 80 81 recently, several authors have reported on the presence of a cusp-like structure on the labial aspect of anterior human teeth (abbott, 1998; jowharji et al., 1992; mcnamara, 1997; mcnamara et al., 1997; schulze, 1987; tomonori and ogouchi, 1991; turner, 1998). this feature is described as a triangular ridge of enamel, or a style near the midline of the tooth, located on the labial surface. the apex of this accessory structure terminates near the occlusal edge. radiographs have shown this style to be made up of enamel and dentine, with sporadic pulp involvement (abbott, 1998; jowharji et al., 1992; mcnamara, 1997; tomonori and ogouchi, 1991). previous studies have referred to this feature as a facial talon cusp, labial talon cusp, and, simply, talon cusp (abbott, 1998; jowharji et al., 1992; mcnamara, 1997). since the talon cusp is more frequently used to refer to an accessory structure on the lingual aspect of the upper teeth, we suggest the use of the term “labial talon cusp.” seven cases of labial talon cusp have been previously reported in the literature. three cases were modern european; mandibular central incisors were affected in two individuals and a maxillary canine was affected in the remaining individual (mcnamara, 1997; mcnamara et al., 1997; schulze, 1987). one case was a modern japanese with a mandibular central incisor involved (tomonori and ogouchi, 1991). a labial talon cusp on the maxillary central incisor has been identified in a modern african american (jowharji et al., 1992). abbott (1998) found a modern australian case with an affected maxillary central incisor. lastly, turner (1998) reported a labial talon cusp found on the maxillary lateral incisor from an archaeological native american anasazi. research and results new cases eight new cases of labial talon cusp have been recorded by the authors. bilateral labial talon cusps were identified archaeologically in the mandibular central incisors of an ainu (japan) (fig. l) and a caddo (texas) (fig. 2). five cases affecting the mandibular central incisors were found among dental casts of living native american pima; three were bilateral (fig. 3) and two unilateral. one unilateral case had the left central incisor rotated 180°, with the labial talon cusp facing the inside of the mouth. one archaeological native american anasazi was found to have a labial talon cusp on a maxillary incisiform supernumerary tooth situated between the central incisors, a mesiodens (fig. 4). there are few data on the frequency of this rare anomaly. our original specimen was encountered during an analysis of 132 native american caddoan crania, from the collections at the texas archaeological research laboratory, university of texas at austin. all permanent teeth were examined. this yielded a labial talon cusp frequency of 0.76% for the caddo. to determine the frequency of labial talon cusps in a large sample of native americans we subsequently examined a series of 835 female and 1,000 male dental casts from the arizona state university a. a. dahlberg native american pima dental casts. this analysis, limited to the mandibular and maxillary permanent incisors, examination of the rare labial talon cusp on human anterior teeth c. lee,* s. e. burnett, and c. g. turner ii department of anthropology, arizona state university, tempe, arizona 85287-2402 abstract the labial talon cusp, a triangular ridge of enamel near the midline of anterior teeth, has been observed in archaeological remains and modern dental patients. the purpose of our report is to describe new cases in order to provide better estimates of its frequency, symmetry, teeth involved, and geographic occurrence. this research was initiated after a labial talon cusp was found in a caddo cranium curated in the texas archaeological research lab at the university of texas at austin. subsequently, we identified additional examples resulting in the total of eight new cases presented here. five cases were identified in the native american pima dental casts from the a. a. dahlberg collection at arizona state university. two of the pima cases were found in a systematic analysis of 1,835 dental casts for a population frequency of 0.11%. additional cases were identified in ainu and anasazi skeletal material. including these new finds, 15 cases of labial talon cusp are now known including native americans, african americans, japanese, australians, and europeans. six cases are maxillary and nine are mandibular. known maxillary cases are unilateral, while 55.6% of the mandibular cases are bilateral. all anterior teeth appear to be affected, but there is no recorded instance of an affected mandibular canine. dental anthropology 2003;16(3):81-83. *correspondence to: ms. christine lee, department of anthropology, arizona state university, tempe, az 85287-2402. e-mail: christine.lee@asu.edu 82 83 yielded two cases for a population frequency of 0.11%. these data indicate the labial talon cusp is a rare trait with a population frequency of less than 1%. casts of the relatives of all five pima individuals were examined since no familial case is known to date. three parents and 19 siblings were examined but no additional labial talon cusp occurred. there is no evidence to suggest the five affected pima were closely related to each other. summary of presently known cases at the present time, a total of 15 individuals have been observed with at least one labial talon cusp (table 1). all cases were found in the permanent dentition. six cases of labial talon cusp were found on the maxillary teeth; all were female and unilateral. three cases involved a maxillary central incisor while one case appeared on a lateral incisor. labial talon cusps were also identified on a maxillary canine and an incisiform supernumerary tooth. there is some uncertainty if the supernumerary tooth exhibits a true talon cusp or some other abnormal morphology. nine cases of labial talon cusp involved the mandibular central incisors alone. eight individuals of the nine were of known sex—two female and six male. expression on the mandibular central incisor was bilateral in five out of nine cases (55.6%). although only 15 cases are known, females appear to express the trait more often in the maxillary teeth, while males account for most cases in the mandibular teeth. there are no cases involving maxillary and mandibular teeth in the same individual. one known case exhibits a labial and a lingual talon cusp on the same tooth (abbott, 1998). group sex teeth source 1. japanese f max. left i1 tomonori et al., 1991 2. african american f max. right i1 jowharji et al., 1992 3. irish f max. right c mcnamara et al., 1997 4. australian f max. left i1 abbott, 1998 5. native american (anasazi) f max. left 12 turner, 1998 6. native american (anasazi) f max. supernumary i this study 7. german ? mand. right i1 schulze, 1987 8. irish m mand. left i1 mcnamara, 1997 9. native american (pima) f mand. left i1, right i1 this study 10. native american (pima) f mand. left i1 this study 11. native american (pima) m mand. left i1, right il this study 12. native american (pima) m mand. left i1 and right i1 this study 13. native american (pima) m mand. left i1 this study 14. native american (caddo) m mand. left i1 and right i1 this study 15. japanese (ainu) m mand. left i1 and right i1 this study table 1. known cases of labial talon cusp fig. 1. japanese (ainu). bilateral expression on mandibular central incisors. fig. 2. native american (caddo). bilateral expression on mandibular central incisors. c. lee et al. 82 83labial talon cusp conclusions this study presents eight new cases of the rare labial talon cusp and the first estimates of population frequencies. the labial talon cusp is rare and found in less than one percent of the population. labial talon cusps have been found on all maxillary and mandibular anterior teeth, except mandibular canines. to date, little evidence indicates a direct relationship between the labial talon cusp described here and the more common lingual talon cusp. possible uses for this trait may be in the research of dental development (jowharji et al., 1998), dental evolution (turner, 1998), or genetic syndromes (tomonori and ogouchi, 1991). hopefully future research will enable us to better understand the etiology and genetic basis of this trait, as well as any possible correlation that may relate to other morphological features of the human dentition. acknowledgments we would like to thank diane e. hawkey for access to the pima collection, darrel g. creel and thomas r. hester for access to the caddo collection, d. gentry steele and donald h. morris for insights, alex chou for dental casting, mike and helen pemberton for access to skeletal material, milton bell and barbara backes for photography, and jennifer huang for assistance. literature cited abbott pv. 1998. labial and palatal “talon cusps” on the same tooth. oral surg oral med oral path 85: 726-730. jowharji n, noonan rg, tylka ja. 1992. an unusual case of dental anomaly: a ‘facial’ talon cusp. j dent child 59:156-158. mcnamara t. 1997. an unusual talon cusp. dental anthropology 11:19. mcnamara t, hauessler am, keane j. 1997. facial talon cusps. int j paediatr dent 7:259-262. schulze c. 1987. anomalien und missbildungen der menschlichen zähne. berlin: quintessenz verlagsgmbh. tomonori t, ogouchi h. 1991. labial talon cusp in a child with incontinentia pigmenti achromians: case report. ped dent 13:236-237. turner cg ii. 1998. another talon cusp: what does it mean? dental anthropology 12:10-12. fig. 3. native american (pima). bilateral expression on mandibular central incisors. fig. 4. native american (anasazi). maxillary incisiform supernumerary tooth with labial talon cusp. al-shorman 2006.4 79 the study of the total collection of the human teeth from the archaeological site of khirbit yajuz has revealed striking results, notably conspicuous oblique dental wear on the first lower molars, premortem and perimortem tooth loss, dental abscesses in the maxilla, and progressive periodontal disease (alshorman, 2003). the frequency of dental caries among the recovered skeletons (n = 120 individuals) is 13.3%, which is within the range of the other byzantine sites in the region (smith et al., 1992; williams et al., 2004). these and other archaeological results suggest a population of low social status whose primary occupation was weaving (al-shorman and khalil, 2006). in the upper jaw, most of the sites of tooth decay had developed into dental abscesses. in contrast, the low frequency of caries and the absence of dental abscesses in the lower jaw might have been triggered by the use of teeth as tools (al-shorman, 2003) that frequently polished the occlusal tooth surface, thereby removing sticky food particles and reducing depths of the fissures. in other words, the rate of dental wear was high enough to inhibit the development of dental caries on the occlusal surfaces of teeth (powell, 1985). the frequency of dental abscesses among the byzantine people of khirbit yajuz was extraordinarily high compared to similar sites; most of the investigated carious lesions had periapical abscesses. a periapical abscess develops when the area surrounding the tip of the root is invaded by bacteria; fluids and dead bacteria accumulate in the periapical region, forming a pocket as part of the phagocytic defense process (scott and turner, 1988). abscesses develop as the fluids break through the alveolar bone. an untreated case may develop a fistula either on the buccal or the lingual side (alexandersen, 1967). a periapical abscess typically is the result of pulp exposure due to rapid attrition, caries, trauma, or periodontal disease (hillson, 1996); all of these factors a byzantine cranium from jordan: a case study in dental anthropology abdulla al-shorman* department of anthropology, yarmouk university, irbid-jordan abstract: this study describes a byzantine cranium from an archaeological site in jordan (khirbit yajuz). this case study illustrates severity of the multiple dental pathologies encountered and speculates on the cause of death. the 21-yers-old female of this study suffered multiple dental abscesses, where the accumulated pus reached the nasal cavity and the maxillary sinuses through a large fistula, probably causing septicemia that may have caused her early death. this case was selected from among similar cases from the site, and it illustrates an extreme, progressive state of caries and the absence of dental hygiene. dental anthropology 2006;19(3):79-82. were present among the yajuz people. the present study presents one of the progressive cases of acute periapical abscesses and periodontal disease. this analysis also extracted the demographic variables of age and sex based on morphology of the cranium and development of the teeth. dealing with the case from a forensic perspective, the study elucidates the probable cause of death. materials and methods the study deals with the remains of one individual represented by a cranium that is dated to the byzantine period, ca. 5th-8th century ad (khalil, 1998, 2001). this cranium was visually assessed for the presence of periapical abscesses, caries, dental wear, and periodontal disease. the sex was estimated after ascádi and nemeskéri (1970), aging after ubelaker (1989), wear according to smith (1984), and abscesses and caries after buikstra and ubelaker (1994). results and discusssion the supraorbital margins are very sharp with only minor prominence of glabella, indicating that the specimen was female. the third right upper molar is not in complete occlusion; it is below the level of the adjacent right second molar. this situation suggests an age of about 21 years (ubelaker, 1989). the maxilla retained five teeth, namely the right canine, right first premolar, right second molar, right third molar, and left first premolar. the other teeth were lost before death (premortem) or around death (perimortem). *correspondence to: abdulla al-shorman, department of anthropology, faculty of archaeology and anthropology, yarmouk university, irbid-jordan e-mail: alshorman@yu.edu.jo 80 tooth type side occlusion first incisor right premortem loss second incisor* right perimortem loss canine right complete occlusion first premolar right complete occlusion second premolar* right perimortem loss first molar* right perimortem loss second molar right in full occlusion third molar right below full occlusion first incisor left postmortem loss second incisor left postmortem loss canine left postmortem loss first premolar left postmortem loss second premolar left in full occlusion first molar left premortem loss second molar* left perimortem loss third molar* left perimortem loss *tooth exhibits a periapical abscess. table 1. maxillary tooth inventory fig. 2. inferior view of the cranium showing the abscesses, dental caries and dental wear. photographed by y. al-zou’bi. fig. 1. an anterior view of the cranium. photographed by y. al-zou’bi. the teeth that are present in occlusion exhibit minor dental wear, suggesting that the woman had a less abrasive diet and/or the teeth did not have enough time to be abraded because she died at a young age. the second right molar possesses two large caries, one on the mesial and the other on the distal cervical margin of the crown. the left second premolar also has a moderate lingual surface caries. periodontal disease is prominent along the tooth arcade, with significant horizontal alveolar bone loss. five teeth exhibit periapical abscesses in advanced stages (table 1). the most noticeable and advanced a. al-shorman 81 of the lacrimal bone are smooth and almost oval in shape. the presumed large amount of pus in the nasal cavity and the maxillary sinuses might have been absorbed by the epithelial tissues lining them. the pus probably infiltrated the blood stream causing septicemia. since the person died during the active stage of the disease, septicemia is the probable cause of her death. the progress of the disease was from the root of the first molar to the palatine bone, followed by the nasal cavity, and then involvement of the maxillary sinus. finally, the orbit was involved, all of which took a considerable amount of time, probably weeks. this extensive invasion stresses the woman’s physiological ability to tolerate and cope with the disease, especially in the absence of medical intervention. conclusion the multiple dental pathologies in this case involve a clear-cut situation of poor dental hygiene in the presence of a rich carbohydrate diet. comparable multiple pathologies were common among the people of khirbit yajuz, especially among skeletal remains of the low social classes. our case is from the yajuz people; the woman belonged to a low social class and probably died of septicemia at around 21 years of age. literature cited ascádi g, nemeskéri j. 1970. history of human life span and mortality. budapest: akadémiai kaidó. alexandersen v. 1967. the pathology of jaws and temporomandibular joints. in: brothwell d, sandison a, editors. diseases in antiquity. springfield: charles c thomas, p 551-595. al-shorman a. 2003. a byzantine tomb from khirbit yajuz, jordan. j paleopathology 15:177-185. al-shorman a, khalil l. 2006. the evidence of weaving at khirbit yajuz in jordan using dental microwear. int j dental anthropol 8:1-9. buikstra j, ubelaker d. 1994. standards for data collection from human skeletal remains. arkansas archaeological survey research series. fayetteville: arkansas archaeological survey research series. hillson s. 1996. dental anthropology. cambridge: cambridge university press. khalil l. 1998. university of jordan’s excavations at khirbit yajuz. annual of the department of antiquities jordan 42:457-472. khalil l. 2001. glass vessels from and miniature jugs from khirbit yajuz cemetery, jordan. levant 33:127138. powell m. 1985. the analysis of dental wear and caries for dietary reconstruction. in: gilbert r jr, mielke j, editors. the analysis of prehistoric diets. orlando: academic press, p 307-383. scott gr, turner cg ii. 1988. dental anthropology. ann one is the right first molar; perforations are present on the buccal and lingual sides of the alveolus. the pus accumulation was so destructive that the surrounding alveolar bone was resorbed for 8 mm above the buccal alveolar line. this resorption also exposed two-thirds of the adjacent second molar root. the amount of pus accumulation was certainly substantial: where it first formed a cyst in the palatine bone and then perforated the hard and soft palates, the fistula is about 3 mm in diameter. the pus seems to have accumulated in the nasal cavity; it is conceivable that the accumulated pus was running out of the individual’s nose and mouth before death. the pus had also resorbed the nasal wall of the right maxillary sinus and the medial wall of the right orbit (the lacrimal bone). edges of the perforation fig. 3. right lateral view showing bone destruction due to periodontal disease. also note the buccal alveolar perforation and the lacrimal bone destruction. photographed by y. al-zou’bi. a byzantine cranium from jordan 82 rev anthropol 17:99-126. smith b. 1984. patterns of molar wear in huntergatherers and agriculturalists. am j phys anthropol 63:39-56. smith p, horowitz l, dujovny l. 1992. the human remains from area h. in: de groot a, ariel d, editors. excavations at the city of david 1978-1985. vol. iii. stratigraphical, environmental, and other reports. qedem monographs of the institute of archaeology, 33. jerusalem, israel: the institute of archaeology, the hebrew university of jerusalem. ubelaker j. 1989. human skeletal remains, 2nd ed. washington, dc: taraxacum press. williams k, el-najjar m, rose j, al-koufahi h, king m, al-awad f. 2004. skeletal biology. in: rose j, burke d, editors. a late byzantine site in north jordan. irbid, jordan: yarmouk university press, p 146-180. a. al-shorman mosharraf and hajian 2004.6 94 95 the mandibular first premolar (lp1) is the smallest premolar in the human dentition and typically has two cusps. its buccal cusp is much larger than the lingual cusp, causing the central groove to be u-shaped, with the bottom of the “u” directed lingually. but, in some instances, the lingual cusp is wider buccolingually and the central groove becomes h-shaped. in these latter cases, the coronal morphology of this tooth is more similar to maxillary premolars (van beek, 1983; ash, 1993). the occlusal morphology of the mandibular second premolar (lp2) is variable with two or more cusps. the variation occurs in the lingual portion of the crown that may present as a single cusp or may be divided into two or three cusps giving a more angular and square outline (loh, 1993). van beek (1983) stated that, like first premolars, various occlusal patterns are seen in the 2-cusp forms with the predominant pattern an h-shaped central groove. in the multiple cusp forms, the lp2 crown appears to have a more-square outline (loh, 1993), with the buccal cusp much broader than either of the lingual cusps. a “y-shaped” form occurs when there is a central pit with three grooves (mesial, distal and lingual developmental grooves) radiating from it (van beek, 1983). in dental textbooks, the occlusal morphology of lp1 and lp2 are described as usually having a “ushaped” central groove on the first premolars and a “y-shaped” groove on second premolars. but in our experience, the anatomy of these teeth is more variable. a literature search revealed a paucity of descriptive information on prevalence and features of the coronal morphology of these teeth. the purpose of the present study was to assess the actual variability of the occlusal groove patterns in a sample of contemporary iranian adolescents. materials and methods this investigation was undertaken in the high schools of isfahan city, iran. the students were screened and only those with erupted mandibular first and second premolars present bilaterally were selected. direct intraoral examination was undertaken. morphological details of the crown: namely the number, position and height of cusps and the sex of the subjects were recorded on prepared forms. data were excluded from the investigation in cases where the teeth were restored, worn or heavily broken. a cusp was defined as a pronounced elevation on the occlusal surface of a tooth terminating in a conical, rounded, or flat surface (jordan and abrams, 1992). four hundred individuals (1,600 teeth: 800 first premolars and 800 second premolars) were analyzed for the present descriptive study. results mandibular first premolar eighty-six individuals (21.5%) had a bilateral hshaped pattern, 280 (70.0%) had a bilateral u-shaped pattern, and 34 (8.5%) were mixed (table 1). chisquare test revealed that there was no sex predilection for pattern of the central groove. but in the mixed abstract: in dental textbooks, the mandibular premolar occlusal morphology has been described as having a predominantly “u-shaped” central groove on the first premolar and a “y-shaped” central groove on the second premolar. in this study, we examined students (n = 400) of isfahan high schools (iran) and first and second premolars were examined bilaterally. morphological features of the crown, number, height and position of cusps, central grooves shape and sex of the teethwere recorded. for the mandibular first premolars, 21.5% of students exhibited h-shape grooves occlusal morphology of the mandibular first and second premolars in iranian adolescents ramin mosharraf* and fatemeh hajian faculty of dentistry, ishfahan university of medical sciences, isfahan, iran *correspondence to: ramin mosharraf, department of prosthodontics, faculty of dentistry, isfahan university of medical sciences, isfahan, iran e-mail: mosharraf@dnt.mui.ac.ir bilaterally; 70.0% had bilateral u-shape grooves; and 8.5% were mixed. for the mandibular second premolars, 73.0% exhibited 2-cusp forms bilaterally; 15.8% had 3-cusp forms bilaterally; and 11.3% were mixed. in the 2-cusp forms, the predominant occlusal pattern was u-shaped (44.0%). in this iranian sample, the predominant occlusal pattern was u-shaped in both the first premolar and second premolar, which contrasts with conventional textbook descriptions. dental anthropology 2004;17(3):94-96. 94 95 group, there was significant difference between males and females (p = 0.0163), with mixed patterns occurring in males more often that females (males = 25, females = 9). mandibular second premolar most cases (292/400; 73.0%) were bilateral 2-cusp forms; 63 (15.8%) were bilateral 3-cusp forms; and 45 (11.3%) were mixed (table 2). chi-square test revealed no sex predilection in the first and second categories but in the mixed groups there was significant difference between males and females (p = 0.004), also with mixed cusp forms occurring more often in males (males = 32, females = 13). various occlusal patterns occurred in the 2-cusp premolar (table 3). the predominant pattern (44.0%) was a u-shaped groove form (p < 0.001). discussion in the iranian sample, 70.0% of cases had a u-shaped central groove pattern on the mandibular p1. but in a study from the ivory coast (adiko et al., 1999) the occlusal morphology of this tooth tended toward the 2cusp mandibular second premolar. among bilaterally symmetric cases the 2-cusp forms were far more common in the iranian that the 3-cusp forms (15.8%). this finding is consistent with other population studies. pederson (1949) gave a frequency of 63.8% in his series of 188 casts of east greenland eskimos. he quoted frequencies of 16.8% and 25.6 % in european (de terra, 1905) and finnish (kajava, 1912) dentitions, respectively. however, in the present study 11.3% of cases were asymmetric (2 cusps on one tooth and 3 cusps on the homologue); data on asymmetry in the other studies were not reported. the lp2 3-cusp form occurred in nearly 16.0% of the iranian sample. this occurrence is not very high. in loh’s study of chinese from singapore (1993), the 3-cusp form constitutes a quarter of the cases studied, and loh considered this trait to be a north asians characteristic. the h-shaped pattern in the 2-cusp form of lp2 might also be an ethnic feature loh (1993), stated that the 3-cusp forms (y-shaped) were an important variation in that (1) no sex predilection is found for its occurrence; (2) development of structures with bilateral presence usually shows minor variations in size and shape; (3) different forms on each side is unusual, and (4) when asymmetry occurs in pattern, it is seen significantly more often in males. conclusion in this study of iranian adolescents the predominant occlusal pattern was u-shaped in both the first and second premolar samples. thus in this population, occlusal morphology of first premolars was like that explained in dental textbooks, but the occlusal anatomy of second premolars is more variable that expected. refrences cited adiko ef, mansilla e, djaha k, assi kd, gnagne ay, mac hc, egnankou jk. 1999. [a comparative study of the occlusal surface of the mandibular first and second premolar in ivory coast]. odontostomatologie tropicale 22:33-37. ash m. 1993. wheeler ’s dental anatomy, physiology and occlusion. philadelphia: wb saunders, p 218240. de terra m. 1905. beitrage zu einer odontographie der menschenrassen. berlin: berlin verlaganstalt. jordan er, abrams l. 1992. kraus’ dental anatomy and occlusion. st louis: mosby year book, p 19. kajava y. 1912. die zähne der lappen. suomen hamm toim 10:1-64. table 1. groove patterns of the mandibular first premolar total groove form males females n % h-shaped 41 45 86 21.5 u-shaped 134 146 380 70.0 mixed 25 9 34 8.5 total 200 200 400 100.0 table 2. cusp number of the mandibular second premolar total number of cusps males females n % 2-cusp forms 143 149 292 73.0 3-cusp forms 25 38 63 15.7 mixed 32 13 45 11.2 total 200 200 400 100.0 table 3. groove patterns of the mandibular second premolar total groove pattern males females n % h-shaped 32 52 84 21.0 u-shaped 85 91 176 44.0 y-shaped 25 38 63 15.7 mixed 58 19 77 19.2 total 200 200 400 100.0 r. mosharraf and f. hajian 96 loh hs. 1998. root morphology of the maxillary first premolar in singaporeans. aust dent j 43:399-402. pederson po. 1949. the east greenland eskimo dentition. copenhagen: ca reitzels forlag, p 129, 161-167. van beek gc. 1983. dental morphology. bristol: john wright and sons, p 70-72, 76-78. decoding your subscription want to know when your subscription to dental anthropology expires? membership in the association and, thus, your subscription to dental anthropology is on an annual basis coinciding with the calendar year. have a look at the mailing label on the envelope that this issue arrived in, and you will see the year for which your dues have been paid. the year is located in parentheses to the right of your name. so, if the mailing label says “(2004)” you are paid to the end of last calendar year. in order to extend your membership, fill-out the relevant portions of the enclosed form—remember to include appropriate payment—and mail or fax it to the secretary-treasurer of the association: dr. heather h. edgar maxwell museum of anthropology msc01 1050 1 university of new mexico albuquerque, new mexico 87131-0001 usa telephone: (505) 277-4415 e-mail: hjhedgar@unm.edu fax: (505) 277-1547 daa web site updated thanks to the efforts of sally graver (ph.d. student, ohio state), the dental anthropology association web site has a new home. the new web site address is: http://192.168.1.2/daa/index.htm this is located on the ohio state university department of anthropology’s server. alma adler (ph.d. candidate, arizona state university) designed the new web site, which currently has links to the membership form, dahlberg prize announcement, and to phil walker’s and ed haagen’s quick-time movies of the dentition. in addition, we plan to make past issues of dental anthropology available on the web site. please visit the site and let us know what you think! http://192.168.1.2/daa/index.htm turner and harris 2004.3 74 75 this communication describes the unusual morphology of maxillary second premolars (fig. 1) that were encountered in an otherwise normal young adult. these teeth are distinctive because of the large accessory cusp that occurs bilaterally on the buccal surface of each maxillary second premolar. we present this case in hopes of stimulating discussion about similar teeth that other researchers have encountered and to solicit suggestions of likely causes of this variant. the case is an 18-4 year old african american male who presented for routine orthodontic treatment. by our inspection (figs. 1, 2) this young male is phenotypically normal aside from the uncommon premolars. all 32 permanent teeth are present, including the third molars where the maxillary teeth have initiated root formation and the mandibular teeth have their crowns mostly formed (fig. 3). the orthodontic issues were (1) a palatally impacted right canine with just 2.5 mm of space between the lateral incisor and first premolar in this quadrant, (2) an anterior openbite with the right central and left lateral incisors in crossbite, and (3) tongue-thrust on swallowing. there is a class i molar relationship (angle) bilaterally. the young man was unaware of his unusual premolars. he did not have a regular dentist, though there are occlusal amalgams on his left and right mandibular first molars (all other teeth are noncarious). these accessory cusps arise from the buccal cingulum. apart from lingual cingula on the lingual aspects of incisors and canines, basal developments are uncommon in humans. the obvious exception is carabelli’s trait that occurs on the protocone of maxillary molars. carabelli’s complex has been amply described (e.g., kraus, 1959; korenhof, 1960; turner and hawkey, 1998), and it is one of the few morphological variants commonly discussed in clinical dental texts (zeisz and nuckolls, 1949; ash, 1993). other cingular traits include (1) the paramolar tubercle of bolk (dahlberg, 1945) and (2) and talon cusps that arise from the lingual cingulum of incisors (e.g., harris and owsley, 1991; lorena et al., 2003; segura-egea et al., 2003; dash et al. 2004). dahlberg brief report: maxillary second premolars with paramolar tubercles robert a. turner and edward f. harris* department of orthodontics, the health science center, university of tennessee, memphis, tn 38163 *correspondence to: edward harris, department of orthodontics, college of dentistry, the health science center, university of tennessee, memphis, tn 38163 e-mail: eharris@utmem.edu (1950) suggests that paramolar cusp is a term applied to “any stylar or anomalous cusps, supernumerary inclusion or eminence occurring on the buccal surfaces of both upper and lower premolars and molars. dahlberg used the term protostylid to distinguish just those cusp-like features occurring on the protoconid of lower molars near the buccal groove. various authors have commented on the association between carabelli’s cusp and size of the crown of the rest of the tooth (garn, 1977; hsu et al., 1997). scott has reported positive statistical associations between various cingular elements, notably (1) among the expressions of lingual tubercles on the maxillary incisors and canines fig. 1. occlusal intraoral view of the young adult african-american described here. by our inspection, the accessory cusps on the second premolars are the only dental features outside normal limits. 76 77 (scott, 1977), (2) between carabelli’s complex and size of the hypocone (scott, 1979; also see review in keene, 1968), and (3) between carabelli’s complex—on the lingual aspect of maxillary molars—and the protostylid—on the buccal aspect of mandibular molars (scott, 1978). noteworthy features of the accessory cusps (fig. 2) are their size and bilateral symmetry. there is no trace of this feature on the first premolar. crown diameters (table 1) were compared to a sample of american blacks (richardson and malhotra, 1975) but these standards are only available for mesiodistal diameters (fig. 4). comparisons also were made to the american white standards reported by harris and burris (2003). our case possesses small mandibular incisors and large mandibular molars, but the up2 with the accessory cusps is unremarkable in these comparisons. this suggests, along with the raw data, that the accessory cusp constitutes part of the normal tooth’s buccolingual width; the cusp is not simply added on to it. this agrees with the observation (fig. 2) that the occlusal tables of the p2s are somewhat compressed buccolingually. normally, the p2 dimension is at least as large as the fig. 2. close-up occlusal views of the second premolars. arch lengths are different in the two quadrants because of the unerupted (impacted) canine on the man’s right. fig. 3. panoramic radiograph. the palatally impacted right canine is noteworthy, but other features appear to be within normal limits. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �� �� � �� �� �� �� �� �� � �� �� �� �� �� �� �� � � � � � �� � � � � � �� � � �� �� � � � � �� ��������� � �� ��������� � �� ��������� ������� �������� fig. 4. plots of z-scores for this case compared to mesiodistal diameters of american blacks (richardson and malhotra, 1975) and mesiodistal and buccolingual dimensions of american whites (harris and burris, 2003). table 1. crown dimensions1 mesiodistal buccolingual tooth right left right left maxilla i1 9.4 9.4 6.7 6.6 i2 7.7 7.4 6.4 6.4 c u 7.9 u 8.4 p1 8.5 8.2 10.7 10.7 p2 7.6 7.8 11.3 11.0 m1 11.1 11.1 12.4 12.5 m2 11.4 11.5 12.1 11.4 mandible i1 6.0 6.0 4.5 4.8 i2 6.8 6.8 5.8 5.8 c 7.4 7.9 7.5 7.5 p1 8.4 8.1 8.3 8.6 p2 8.3 7.8 9.1 9.6 m1 13.5 13.0 12.2 12.3 m2 ie 12.4 11.6 11.8 1u = unerupted; ie = incompletely erupted. r.a. turner and e.f. harris 76 77 p1, but, on the left, the paracone-protocone distance is 6.0 mm on p1 and 5.9 on p2. on the right where the accessory cusp is slightly larger, the intercusp distance is 6.8 mm on p1 but just 5.8 on p2—again indicating that part of the normal tooth mass has been recruited for production of the extra cusp. periapical radiographs of these premolars (fig. 5) are unremarkable. both of these second premolars possess just one root, as is the norm (ash, 1993), and there appears to be just a single, normal pulp chamber. crown morphology of the second premolars is not unusual. there are two main cusps separated by a central developmental groove. there are moderatesize mesial and distal ridges. the right up2, that is slightly larger than its antimere, has a distal protocone ridge that is absent on the left tooth. the accessory cusp has a lunate (curvilinear) cross-section; it is so large mesiodistally that it essentially “wraps onto” the curvature of the buccal margin of the paracone (buccal cusp). the buccal aspect of the cusp itself is smooth and featureless, descending straight to the cementoenamel junction. the accessory cusp has a single elevation (cusp) with the apex located exactly buccal of the paracone’s apex. distance between these cusp tips is 1.25 mm on both the right and left tooth. notably, these accessory cusps would never enter occlusion. that is, one might suppose that the cusp might be adaptive by contributing to the crown’s overall occlusal area. as is normal, though, the paracone (buccal cusp) of the maxillary premolar overhangs the buccal cusp of the lower premolar and the maxillary premolar ’s lingual cusp (protocone) occludes into the lower premolar ’s central fossa. consequently, regardless of how worn these premolars might become, the accessory cusp will always be buccal of the mandibular tooth—with nothing to occlude against. it seems doubtful, then, that this morphological variant has any adaptive significance, at least functionally. heights of the accessory cusps are about 1⁄2 mm short of the apices of the paracones, and these cusps have free apices that jut about 2 mm occlusal of where the accessory cusp melds into the paracone. this anatomy is relevant because it means that the cusp developed from its own enamel knot rather than proliferating at a later time from the paracone. enamel knots are sites of nondividing cells that form during the bell stage of tooth formation. they occur in the stellate reticulum as projections from the inner enamel epithelium (bhaskar, 1980). enamel knots have been recognized for over a century (reviewed in butler, 1956), though their function was unknown. recent work by molecular biologists (jernvall et al., 1994; thesleff et al., 2001) has shown that knots produce substances that promote mitotic growth in the adjacent iee. since the knots themselves are nondividing, this creates irregularities in the iee that become cusps (jernvall et al., 1994, 1998; jernvall, 2000). it seems that the primary enamel knot, which is the most obvious on light microscopy and the earliest to form, determines the site of the tooth’s occlusal table (or its counterpart in the simpler anterior teeth), while later-forming ‘secondary’ enamel knots coincide with formation of the individual cusps (thesleff and jernvall, 1997; thesleff et al., 2001; thesleff, 2003). separate enamel knots seem to coincide with separate centers of enamel formation since amelogenesis invariably progresses gingivally (hillson and bond, 1997). in the present case, it seems that an “accessory” enamel knot developed buccal to the presumptive paracone on the left and right second premolars, but not on the earlierforming first premolars mesial to them. we have contacted a few experts in the field concerning these teeth. some have not encountered such a variant. others stated that they have seen similar cases, but did not bother to record them. certainly, the frequency of this variant is rare. readers who have seen similar cases—or have comments on this report—are encouraged to contact the authors. literature cited ash mm jr. 1993. wheeler’s dental anatomy, physiology and occlusion, 7th ed. philadelphia: wb saunders. bhaskar sn. 1980. orban’s oral histology and embryology, 9th ed. st louis: cv mosby company. butler pm. 1956. ontogeny of the molar pattern. biol rev 31:30-70. dahlberg aa. 1945. the paramolar tubercle (bolk). am j phys anthropol 3:9-103. dahlberg aa. 1950. the evolutionary significance of the protostylid. am j phys anthropol 8:15-25. dash jk, sahoo pk, das sn. 2004. 2004. talon cusp associated with other dental anomalies: a case report. int j paediatr dent 14:295-300. garn sm. 1977. genetics of tooth development. in: mcnamara ja, editor. the biology of occlusal fig. 5. periapical radiographs of the maxillary second premolars. paramolar tubercles 78 79 development. ann arbor, mi: craniofacial growth series, p 61-88. harris ef, burris bg. 2003. contemporary permanent tooth dimensions, with comparisons to g.v. black’s data. j tenn dent assoc 83:25-29. harris ef, owsley dw. 1991. talon cusp: a review with three cases from native north america. j tenn dent assoc 71:20-22. hillson s, bond s. 1997. relationship of enamel hypoplasia to the pattern of tooth crown growth: a discussion. am j phys anthropol 104:89-103. hsu jw, tsai p, liu k, ferguson d. 1997. logistic analysis of shovel and carabelli’s tooth traits in a caucasoid population. forensic sci int 89:65-74. jernvall j. 2000. linking development with generation of novelty in mammalian teeth. proc natl acad sci 97:2641-5. jernvall j, aberg t, kettunen p, keranen s, thesleff i. 1998. the life history of an embryonic signaling center: bmp-4 induces p21 and is associated with apoptosis in the mouse tooth enamel knot. development 125:161-169. jernvall j, kettunen p, karavanova i, martin lb, thesleff i. 1994. evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation: non-dividing cells express growth stimulating fgf-4 gene. int j dev biol 38:463-469. keene hj. 1968. the relationship between carabelli’s trait and the size, number and morphology of the maxillary molars. arch oral biol 13:1023-1025. korenhof caw. 1960. morphogenetical aspects of the human upper molar. utrecht: uitgeversmaatschappij neerlandia. kraus bs. 1959. occurrence of the carabelli trait in southwest ethnic groups. am j phys anthropol 17: 117-123. lorena sc, oliveira dt, odellt ew. 2003. multiple dental anomalies in the maxillary incisor region. j oral sci 45:47-50. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 68:157-164. scott gr. 1977. lingual tubercles and the maxillary incisor-canine field. j dent res 56:1192. scott gr. 1978. 1978. the relationship between carabelli’s trait and the protostylid. j dent res 57: 570. scott gr. 1979. association between the hypocone and carabelli’s trait of the maxillary molars. j dent res 58:1403. segura-egea jj, jimenez-rubio a, rios-santos jv, velasco-ortega e. 2003. dens evaginatus of anterior teeth (talon cusp): report of five cases. quintessence int 34:272-277. thesleff i. 2003. developmental biology and building a tooth. quintessence int 34:613-620. thesleff i, jernvall j. 1997. the enamel knot: a putative signaling center regulating tooth development. cold spring harb symp quant biol 62:257-267. thesleff i, keranen s, jernvall j. 2001. enamel knots as signaling centers linking tooth morphogenesis and odontoblast differentiation. adv dent res 15:14-18. turner cg ii, hawkey de. 1998. whose teeth are these? carabelli’s trait. in: lukacs jr, editor. human dental development, morphology, and pathology: a tribute to albert a. dahlberg. eugene: university of oregon anthropological papers, no 54, p 41-50. zeisz rc, nuckolls j. 1949. dental anatomy. st louis: cv mosby company. r.a. turner and e.f. harris rodriguez and moreno 2006.1 65 dental anthropology can be viewed as the collaborative effort of anthropology, clinical dentistry, biology, paleontology, and paleopathology. the resulting knowledge base permits the study, analysis, interpretation, and understanding of information derived from the human dentition through their morphological, evolutionary, pathological, cultural and therapeutic variations. these structural considerations are viewed against a people’s culture, notably the conditions of life, diet, and adaptation processes. the varied sorts of data studied include nonmetric traits, metric traits, oral and dental diseases, and structural modifications of the teeth. dental morphology, particularly the study of nonmetric dental traits (ndt), involves genetically-modulated trait expressions that can be used for comparisons within and among populations (scott and turner, 1997, 1998; rodríguez cd, 2003, 2005; rodríguez and delgado 2000; rodríguez jv, 2003). more than 100 ndt of dental crowns and roots have been described and standardized internationally using various methodologies. their study and investigation have demonstrated that: (a) they possess high taxonomic value; (b) they can be used to estimate biological relationships among diverse populations, which allows comparative analyses of the historical, cultural and biological development of primitive and modern human groups; (c) most ndt have low sexual dimorphism, low correlations among features, and low correspondence between frequency and geography; (d) they are easily observed and recorded; and (e) they can be used to evaluate population differences according to micro-evolutionary processes, that, in turn, generate information about human movements and contacts that have produced groups’ ethnic variation (scott and turner, 1997; zoubov, 1997; rodríguez jv, 2003). within the broad study of dental morphology, one feature that stands out is the tubers paramolares. these ndts are not common, and, especially in the clinical paramolar tubercle in the left maxillary second premolar: a case report. carolina rodríguez1 and freddy moreno2* 1department of orthodontics and 2oral and maxillofacial surgery research group (dental anthropology and forensic dentistry), school of dentistry, university of valle, cali, colombia. abstract: this is a case report describing a paramolar tubercle occurring on the buccal surface of left upper second premolar (tooth 25). from the perspective of dental anthropology, this morphological feature, though uncommon, may be useful for classification and identification. dental anthropology 2006;19(3):65-69. *correspondence to: freddy moreno, universidad del valle sede san fernando, escuela de odontología, calle 4b no. 36-00 edificio 132 oficina 308. a.a. 25360, cali colombia e-mail: freddyodont@hotmail.com dental literature, they are viewed as supernumerary cusps or ill-defined anatomical variations. basically, paramolar tubercles occur as accessory cusps located on the buccal or lingual surface of the primary and succedaneous teeth, involving both the maxillary or mandibular tooth types. several of these morphological variants are broadly recognized in the dental anthropological literature, such as the dental tubercle on the lingual surface of the upper lateral incisors; the utoaztecan or distosagittal crest on the buccal surface of the upper first premolar; carabelli´s trait on the lingual surface of the mesolingual cusp of the upper molars; the parastyle on the buccal surface of the upper molars; the protostylid on the buccal surface of the low first molars; and paramolar tubercles, generally developed on the buccal surfaces of the upper and low premolars and molars (zoubov, 1997; turner and harris, 2004). paramolar tubercles one ndt that has been described as an accessory or supernumerary cusp, was defined by a. a. dahlberg in 1950 as a paramolar tubercle, a term applied nonspecifically to a style or cusp of supernumerary character that is developed on the buccal or lingual surfaces of the upper and low premolars and molars (turner and harris, 2004). developmentally, dental cusps begin their formation during the early bell stage, well before calcification of the tooth has begun. the cells of the internal epithelium proliferate and produce activators and inhibitors while they are being deposited in sequential layers from the 66 cusp apex toward the neck of the crown starting from an enamel knot. the activator produces a primary enamel knot until the concentration reaches a threshold that induces an inhibitor that neutralizes the activator. once a primary enamel knot has developed, it subsequently disappears by means of apoptosis and secondary enamel knots may appear. molecular biologists are beginning to understand the genes that code and control the expression of the activator and the inhibitor that modulate the rhythm and quantity of enamel deposition. these transient gene expressions modulate the formation and elevation of the peaks and crests leaving among them furrows and grooves. consequently, the formation of a ndt (a cusp, for example) begins with primary or secondary enamel knot. the form of the ndt is influenced by the amount (thickness) of enamel deposited, size of the crown, its relationship with other ndt, and its internal relationship with the dentine. the ndt’s configuration depends, on one hand, on the molecular patterns that are genetically determined and, on the other hand, on the trait’s relationship with other morphological features (butler, 1995; jernvall et al., 1994; jernvall and jung, 2000; jernvall and thesleff, 2000; line, 2001; thesleff and sharpe, 1997). dental studies in the field of the molecular biology derive in part from the work of thesleff et al. (e.g., 2001). research demonstrates that the primary enamel knot configures the occlusal table of premolars and molars, while secondary enamel knots individually constitute the cusps during amelogenesis (thesleff, 2003; turner and harris, 2004). in the case of the paramolar tubercle, turner and harris (2004) suggest that such cusps arise during the morphogenesis process starting from an accessory enamel knot developed at the surface where the feature’s apex forms. it seems that these tubercles do not provide any functional adaptation, such as enlarging the occlusal (masticatory) surface, because these tubercles do not enter into function; they do not occlude against any cusp or groove of the antagonist tooth. fig. 1. clinical front view: paramolar tubercle on the left maxillary second premolar (arrow). fig. 2. clinical right view. where the premolars lack any evidence of a tubercle. fig. 3. clinical right view: paramolar tubercle on the left maxillary second premolar (arrow). fig. 4. clinical oclusal view: paramolar tubercle on the left maxillary second premolar (arrow). c. rodriguez and f. moreno 67 to date, there is very little information about racial differences in the frequencies of paramolar tubercles, primarily because of their apparently low occurrence overall. likewise, no pedigree analysis seems to have been conducted, though their mode of inheritance seems to be complex. alternatively, their expression may suggest a genetic relationship between individuals. for instance, if the tubercle were found in two coeval individuals in a population, this increases the likelihood that the persons are genetically related, which can be useful for forensic identification (zoubov, 1997; edgar, 2005). case report the subject is an eleven-year-old girl attending the orthodontic clinic at the school of dentistry of the university of the valley, colombia. assessment of the maxillofacial skeleton disclosed a slight class ii sagittal molar relationship; upper and low arches were of an oval form; there was slight mandibular retrognathism; the facial form was mesofacial and there was a vertical growth pattern. diagnosis of the soft tissue showed a convex facial profile, a moderate mentolabial furrow, a normal nasolabial angle, protrusion of both the upper and lower lips, and an increased height of the inferior third of the face. the stomatoghnatic functional diagnosis disclosed bruxism and a preference for unilateral right mastication. the dental diagnosis fig. 5. clinical frontal view of the articulated study models: paramolar tubercle on the left maxillary second premolar (arrow). fig. 6. left view of the articulated study models: paramolar tubercle on the left maxillary second premolar (arrow). fig. 7. oclusal view of the maxillary study model: paramolar tubercle on the left maxillary second premolar (arrow). fig. 8. oclusal view of the maxillary study model: paramolar tubercle on the left maxillary second premolar (arrow). paramolar tubercle 68 showed that the girl presents a complete permanent dentition (omitting the third molars), a class i molar malocclusion, a class ii canine relationship, proclination of the mandibular incisors, moderate crowding in both arches, deviation of the dental midlines, and traumatic occlusion. this ndt of interest here is a unilateral paramolar tubercle that on the buccal surface of the upper left second premolar. viewed in the frontal plane (figs. 1, 5), the tubercle presents a free cusp apex that does not reach the occlusal plane. indeed, the tubercle is out of function since there is no occluding anatomical structure on the opposing mandibular teeth. in buccal view (figs. 3, 6, 9), the tubercle constitutes a triangular prominence with its base below the gingival margin and its apex oriented occlusally. this cusp is aligned with that of the premolar’s buccal cusp. from the occlusal view (figs. 4, 7, 8), one can appreciate the symmetrical prominence of the tubercle, which is centered mesiodistally along the tooth’s buccal surface. the longitudinal furrow is evident here, and it runs mesial to distal, separating the tubercle from the premolar’s primary cusp. other ndts that can be appreciated in the patient are: (a) crowding of the upper incisors (figs. 4, 7), where the lateral incisors are lingually displaced and there is a consequent tooth-size to arch-size discrepancy (rodríguez, 1989; bernabé and flores, 2006). (b) slight incisor winging (figs. 4, 7), where both upper central incisors are slightly rotated distolingually relative to the midline; in this case, winging probably is secondary to inadequate arch space for correct incisor alignment (peck and peck, 1975; rodríguez jv, 1989, 2003; turner et al., 1991; nandini et al., 2005; bernabé and flores, 2006). (c) cusp 7 (grade 5) occurs bilaterally, which is an ndt characteristic of negroid populations (zoubov, 1997). (d) cusp 6 (grade 2) occurs bilaterally. (e) a deflecting wrinkle (grade 3) can be seen on the first molars. (f) the molar cusp arrangement yields a y6 groove pattern (mesiolingual cusp contacts with the distobuccal cusp at the central groove). (g) a protostylid pit occurs bilaterally (fig. 10), which is a common ndt in mixed population from colombia (moreno et al., 2004; moreno and moreno, 2005; aguirre et al., 2006). recommendations it is important to recognize that although some ndts, including the paramolar tubercles, only occur in low frequencies, they should not be classified as anomalous (a perspective common in clinical dentistry) since they are normal morphological features of the dentition. this morphological variation is evidenced by the diverse trait frequencies among world populations. of course, this variability often is capitalized on in the processes of an individual’s forensic identification. it should be noted that, during orthodontic treatment, paramolar tubercles often are removed by ameloplasty (i.e., the selective removal of enamel by grinding) because they interfere with cementation of the brackets and correct alignment of orthodontic archwires. however, this clinical procedure should be considered a last option, since it involves the mutilation of an epigenetic variant of the dental morphology. it is important that ndts are described systematically (by form and position) in each person’s clinical dental history because these variants are of discriminatory value and because of their usefulness in the identification processes carried out during the technical and scientific exercise of forensic dentistry. literature cited aguirre l, castillo d, solarte d, moreno f. 2006. frequency and variability of five non-metric dental fig. 9. buccal view of the maxillary study model: paramolar tubercle on the left maxillary second premolar (arrow). fig. 10. numerical codes are: (1) deflecting wrinkle; (2) protostylid; (3) cusp 6; and (4) cusp 7. c. rodriguez and f. moreno 69 crown traits in the primary and permanent dentitions of a racially mixed population from cali, colombia. dental anthropology 19:39-47. bernabé e, flores-mir c. 2006. dental morphology and crowding: a multivariate approach. angle orthod 76:20-25. butler pm. 1995. ontogenetic aspects of dental evolution. int j dev biol 39:25-34. edgar hj. 2005. prediction of race using characteristics of dental morphology. j forensic sci 50:1-5. jernvall j, kettunen p, karavanova i, martin lb, thesleff i. 1994. evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation. int j dev biol 38:463-469. jernvall j, jung hs. 2000. genotype, phenotype and develpomental of biology of molar tooth characters. yrbk phys anthropol 43:171-190. jernvall j, thesleff i. 2000. reiterative signaling and patterning during mammalian tooth morphogenesis. mech develop 92:19-129. line s. 2001. molecular morphogenetic fields in the development of human dentition. j theor biol 211:67-75. moreno f, moreno sm, díaz ca, bustos ea, rodríguez jv. 2004. prevalence and variability of eight nonmetric dental traits in students of cali, colombia. colomb med 35(supl 1):17-23. (in spanish) moreno sm, moreno f. 2005. eight non-metric dental traits in alive racially mixed population from cali, colombia. int j dental anthropol 6:14-25. nandini v, utreja a, goyal a, chawla hs. 2005. winged maxillary central incisors with unusual morphology: a unique presentation and early treatment. angle orthod 75:427-431. peck s, peck h. 1975. orthodontic aspects of dental anthropology. angle orthod 45:95-102. rodríguez cd. 2003a. prehispanic dental anthropology: biological variation and distances in the population buried in the pre-hispanic cemetery of obando, valle del cauca, colombia between the centuries viii and xiii a.d. miami: syllaba press. (in spanish) rodríguez cd. 2005. dental anthropology and your importante in the human groups study. rev fac odont univ ant 16:52-59. (in spanish) rodríguez cd, delgado me. 2000. dental anthropology: a brief definition. int j dental anthropol 1:2-4. rodríguez jv. 1989. introducción a la antropología dental. cuadernillo de antropología no. 19. universidad nacional de colombia, facultad de ciencias humanas, departamento de antropología. santa fe de bogotá. rodríguez jv. 2003. teeth and human diversity: dental anthropology advances. bogotá: universidad nacional of colombia. (in spanish) scott gc, turner ii cg. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. london: cambridge university press. scott gc, turner ii cg. 1998. dental anthropology. ann rev anthropol 17:99-126. thesleff i. 2003. developmental biology and building a tooth. quintessence int 34:613-620. thesleff i, sharpe p.1997. signalling networks regulating dental. mech develop 67:111-123. thesleff i, keranen s, jernvall j. 2001. enamel knots as signaling centers linking tooth morphogenesis and odontoblast differentiation. adv dent res 15:14-18. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelly ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss inc, p 13-31. turner ra, harris ef. 2004. maxillary second premolars with paramolar tubercles. dental anthropology 17:75-78. zoubov aa. 1998. the dental anthropology and de forensic practice. maguaré 13:243-252. (in spanish) paramolar tubercle ullinger 2002.4 22 23 a multi-year research project led by dr. susan sheridan of the university of notre dame has been focusing on the health and daily life of the inhabitants of a byzantine monastery in jerusalem. over 15,000 bone fragments and 1,500 teeth have been recovered from the burial crypt at the monastery. the skeletal remains indicate that approximately 93% of the collection was male and that more than half of the individuals were over age 40 at the time of death (sheridan, 2000). the present study is designed to determine the possible genetic affinities of the monks. empress eudocia built the monastery of st. stephen just north of the jerusalem city walls in ad 428. the monastery was in use during the height of the byzantine influence in the near east, until the islamic conquest in ad 614, at which time it is believed to have been destroyed. this period was a time of great growth and development in the region. numerous historical records speak of travelers and pilgrims entering the “holy land” at this time (binns, 1994; chitty, 1966; hirschfeld, 1992; hunt, 1982; wilkinson, 1976). many people made pilgrimage, eventually returning home to tell others of their journeys. others remained in the city once they arrived, as is evident by the population growth in the area at that time (broshi, 1979). the identity of those who inhabited the monasteries has recently been debated. historical records suggest that these monks had been pilgrims coming together from all over europe, africa, and asia (binns, 1994; hirschfeld, 1992). israel hershkovitz (1988:58) uses this idea to argue “the remains in the graves [around early christian pilgrimage to a byzantine monastery in jerusalem—a dental perspective jaime m. ullinger department of anthropology, arizona state university, tempe, az 85287 correspondence to: jaime ullinger, department of anthropology, arizona state university, box 872402, tempe, az 85287-2402. e-mail: jaime.ullinger@asu.edu abstract the presence of 30 morphological traits was scored on over 1,500 teeth from a bone repository located at st. stephen’s, an urban byzantine monastery in jerusalem. the frequencies of dental traits found in the sample were compared with frequencies of the same traits in seven other groups (compiled from published data) in order to determine possible biological affinities of the monks. the mean measure of divergence (mmd) statistic was used to statistically analyze the phenetic/ genetic similarity among the groups. the genetic a byzantine city in the southern levant] are those of the native population and not of intrusive monks”. however, the monks may be members of the native population themselves, and not “intrusive”, as often suggested. scholars now question the validity of historical texts, arguing that the historical records may only reflect the lives of the elite; perhaps indigenous people made up the majority of inhabitants in a monastery (binns, 1994; hunt, 1982; wilkinson, 1976). although binns (1994) argues that the monks from asia minor appear to be underrepresented historically, he also states, “the monks of the palestinian desert had a double vocation. they were both pilgrims and monks” (binns, 1994: editor’s note: ms. ullinger’s paper was awarded first prize for 2002 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. jaime m. ullinger background of this group of monks is interesting because historical sources suggest that many foreigners may have been present in monasteries during this time period as pilgrims. some argue that their presence is exaggerated, however, and that the majority of monks were from the surrounding region. the results suggest that many of the monks were most likely from the region, but that the presence of foreigners (particularly european foreigners) cannot be ruled out using dental evidence. 22 23 13). despite numerous primary sources, the origins of monks during this period are not well known. dental morphological traits are used in the present study to assess the biological relationships among the monks and other groups. dental morphological traits have been used in numerous studies to test the genetic relationships of groups (scott and turner, 1997; turner, 1987; irish, 1998; scott et al., 1983). these traits are strongly controlled by genetics and their use is particularly important when studying a collection such as this one, where the remains are commingled, as the traits are not strongly influenced by sex or side. materials and methods using the arizona state university dental anthropology system (asudas), the author analyzed the morphological traits of more than 1,500 teeth from byzantine st. stephen’s. the collection was scored for over 30 traits; however, for this study only 17 crown traits are analyzed because they are the traits that all eight samples have in common (table 1). the data for the seven other samples are taken from published material. the teeth from st. stephen’s were mostly loose teeth found in various layers of a collection of bones excavated from underneath a burial bench in the underground crypt of the monastery (sheridan, 2000). because most of the teeth were loose, and the identity of individuals impossible, all possible teeth were scored initially for all traits. then, each tooth type was looked at to determine which side had the most teeth present. the side represented by the largest number of teeth was chosen to represent the group as a whole. st. stephen’s was compared with seven other samples. the eight samples are labeled byzantine st. stephen’s (bss), ein gedi (egd), lejjun (lej), early egypt (eeg), north africa (naf), early near east (ene), historic near east (hne), and historic north europe (hno). the ein gedi sample is taken from lipschultz (1996). it represents a site occupied from the late hellenistic to the early byzantine period (200 bc-ad 640). its location is less than 50 km from jerusalem, and occupation was contemporaneous with st. stephen’s monastery. the sample from lejjun, a modern-day site inhabited by bedouin in jordan, is taken from roler (1992). the samples of early egypt (1943 bc-258 ad), and north africa (19th-20th century) were collected by irish (1993). the early near east (8200-1700 bc), historic near east (100bc-present), and historic north europe (ad 150-present) samples were taken from a variety of sources, as compiled by hawkey (1998). each of the samples was compared with all other samples using the mean measure of divergence (mmd) statistic. this statistic is a relative measure of biological affinity between the populations and assumes that the phenotype approximates the genotype (irish, 1998). a lower number indicates similarities in phenetic/genetic affinity, while a higher number indicates a dissimilarity. results the mmd values for each sample comparison are presented in table 2. the byzantine collection was most closely related to the samples from historic north europe, early near east, and early egypt. the sample was most divergent from the ein gedi sample. the relatively smaller mmds found when comparing the site with larger, regional groups (comprised a byzantine monastery in jerusalem table 1. morphological traits used in the study trait tooth analyzed presence absence shoveling upper first incisor 3-7 0-2 double shoveling upper first incisor 2-6 0-1 interruption grooves upper second incisor + tuberculum dentale upper second incisor 1-6 0 canine mesial ridge upper canine 1-3 0 carabelli’s cusp upper first molar 5-7 0-4 cusp 5 upper first molar 1-5 0 enamel extensions upper first molar 2-3 0-1 hypocone absence upper second molar 0-1 2-5 parastyle upper third molar 1-5 0 cusp 6 lower first molar 1-5 0 cusp 7 lower first molar 1-5 0 4-cusp lower second molar lower second molar 4 5,6 y-groove pattern lower second molar y +, x deflecting wrinkle lower first molar 3 0-2 distal trigonid crest lower first molar 1 0 protostylid lower first molar 1-8 0 24 25 of multiple sites), and larger mmds found when comparing the site with smaller, single-site groups is to be expected. the larger, regional groups should show greater affinity with individual sites, while specific groups making up the regional groups will show less affinity for each other, as the larger groups are meant to represent all the smaller groups. the larger, regional groups will be discussed first, followed by the smaller, single-site groups. the mmd values are also illustrated in terms of these group divisions (see tables 3 and 4). discussion the st. stephen’s monastery group was found to be dentally most similar to historic north europe (mmd = 0.113; sd = 0.024), followed by the early near east (mmd = 0.129; sd = 0.027) and early egypt (mmd = 0.135; sd = 0.027). the standard deviations for each place them well within range of each other. this indicates that the group from the monastery is fairly closely related to all three groups equally. the historic north europe group was not strongly related to the early near east group (mmd = 0.223), but was very closely related to the early egypt group (mmd = 0.055). this may reflect the large number of people from modern populations in this category (including “american whites”). this similarity presents several interesting questions beyond the scope of this paper; however, this interesting correlation should be noted. the relation of the st. stephen’s group to both groups in the near east and europe suggests that the people inhabiting the monastery were perhaps composed of both indigenous and foreign populations. this result is somewhat difficult to determine, as the near east is a major geographical crossroads. nevertheless, the statistics suggest that the inhabitants buried at the monastery are strongly related to both historic north europeans and people from the early near east. the comparison of the monastery with singlesite samples is also interesting. the group from the monastery is more closely related to modern-day bedouin from the site of lejjun (mmd = 0.198) than they are to the ein gedi group (mmd = 0.395). the ein gedi group lived less than 50 km from the jerusalem monastery during the same time period, yet are quite dentally dissimilar. however, the large mmd values for the ein gedi group compared with almost every other group suggests that the group may have been quite homogenous and endogamous (possibly for religious reasons). it is unclear as to why these two groups are so divergent. table 2. mean measure of divergence (mmd) values among all groups taken pairwise bss hno ene eeg naf hne lej egd byzantine st. stephen’s (bss) 0.113* 0.129* 0.135* 0.148* 0.160* 0.198* 0.395* historic north europe (hno) 0.113* 0.223* 0.055* 0.101* 0.225* 0.264* 0.191* early near east (ene) 0.129* 0.223* 0.126* 0.159* 0.069* 0.047 0.301* early egypt (eeg) 0.135* 0.055* 0.126* 0.022 0.127* 0.118* 0.131* north africa (naf) 0.148* 0.101* 0.159* 0.022 0.267* 0.174* 0.108* historic near east (hne) 0.160* 0.225* 0.069* 0.127* 0.267* 0.059 0.381* lejjun (lej) 0.198* 0.264* 0.047 0.118* 0.174* 0.059 0.340* ein gedi (egd) 0.395* 0.191* 0.301* 0.131* 0.108* 0.381* 0.340* * indicates a statistically significant mmd value (p < 0.05). table 3. mmd values between st. stephen’s and multi-site samples bss hno ene eeg naf hne bss 0.113* 0.129* 0.135* 0.148* 0.160* hno 0.113* 0.223* 0.055* 0.101* 0.225* ene 0.129* 0.223* 0.126* 0.159* 0.069* eeg 0.135* 0.055* 0.126* 0.022 0.127* naf 0.148* 0.101* 0.159* 0.022 0.267* hne 0.160* 0.225* 0.069* 0.127* 0.267* * indicates a statistically significant mmd value (p < 0.05). a byzantine monastery in jerusalem 24 25 conclusions the people living in the byzantine monastery of st. stephen’s are dentally most similar to historic north europeans and other people from the near east. it is quite possible that the teeth scored came from individuals both foreign and indigenous. there are very few contemporaneous samples to compare the byzantine group to; the one sample available showed that the two groups were very divergent. future research will compare the group to more samples and focus on gaining more information on groups similar to the monks, particularly those from the byzantine period. acknowledgements i would like to thank dr. susan g. sheridan for allowing me to examine the dental remains, for including me in the project, and for providing the funding for the study. thanks also to l’école biblique et archéologique française in jerusalem for access to the collections. i am indebted to dr. diane hawkey who provided an immense amount of direction and made numerous suggestions for this paper. this research was funded through the generous support of the neh and the institute for scholarship in the liberal arts at the university of notre dame. literature cited binns j. 1994. ascetics and ambassadors of christ: the monasteries of palestine 314-631. oxford: oxford university press. broshi m. 1979. the population of western palestine in the roman-byzantine period. bull amer sch oriental res 236:1-10. chitty d. 1966. the desert a city: an introduction to the study of egyptian and palestinian monasticism under the christian empire. oxford: basil and blackwell. hawkey de. 1998. out of asia: dental evidence for affinities and microevolution of early populations from india/sri lanka. ph.d. dissertation, department of anthropology, arizona state university. hershkovitz i. 1988. the tell mahrad population in southern sinai in the byzantine era. isr expl j 38: 47-58. hirschfeld y. 1992. judean desert monasteries of the byzantine period. new haven: yale university press. hunt e. 1982. holy land pilgrimage in the later roman empire ad 312-460. oxford: oxford university press. irish jd. 1993. biological affinities of late pleistocene through modern african aboriginal populations: the dental evidence. ph.d. dissertation, department of anthropology, arizona state university. irish jd. 1998. ancestral dental traits in recent subsaharan africans and the origins of modern humans. j hum evol 34:81-98. lipschultz jg. 1996. who were the natufians? a dental assessment of their population affinities. m.a. thesis, department of anthropology, arizona state university. roler kl. 1992. near eastern dental variation past and present. m.a. thesis, department of anthropology, arizona state university. scott gr, turner cg ii. 1997. the anthropology of modern human teeth. cambridge: cambridge university press. scott gr, potter rhy, noss jf, dahlberg aa, dahlberg ta. 1983. the dental morphology of pima indians. am j phys anthropol 61:13-31. sheridan sg. 2000. ‘new life the dead receive’: the relationship between human remains and the cultural record for byzantine st. stephen’s. rev bibl 106:574-611. turner ii cg. 1987. late pleistocene and holocene population history of east asia based on dental variation. am j phys anthropol 73:305-321. wilkinson j. 1976. christian pilgrims in jerusalem during the byzantine period. palest explor q n.s.: 75-101. table 4. mmd values between st. stephen’s and single site samples bss lej egd bss 0.198* 0.395* lej 0.198* 0.340* egd 0.395* 0.340* * indicates a statistically significant mmd value (p < 0.05) a byzantine monastery in jerusalem irish et al. 2004.5 28 29 in january and february of 2003, members of the combined prehistoric expedition, under the direction of romuald schild, polish academy of sciences, continued an ongoing investigation of neolithic archaeological sites in upper egypt’s western desert. one goal of the field season was to complete the excavation of a cemetery near gebel ramlah, a promontory located approximately 30 km northwest of nabta playa (see wendorf and schild, 2001), and some 250 km southwest of aswan (fig. 1). previous fieldwork at the cemetery, which was originally discovered in 2000, revealed three concentrations of human skeletons and grave goods. during 2001, the easternmost concentration was excavated, and 30 sets of remains were recovered. typological analyses of associated pottery and other artifacts originally suggested that they date to the late neolithic period. however, recent radiocarbon dating (kobusiewicz et al., n.d.) places them in the first half of the fifth millennium bc, which corresponds (see wendorf et al., 1984; wendorf and schild, 1999, 2001) to an early final neolithic assignation. of the many finds at the cemetery, one of the more interesting entails evidence of extreme care that was given to those remains disturbed by later inhumations. beyond collecting all of the bones and grave goods for secondary burial, the neolithic gravediggers also made an effort to recover dental remains that had fallen from their jaws during handling. in two cases, teeth had been reinserted into the alveoli; this action was discerned because several were found to have been placed in incorrect anatomical positions (irish et al., 2003). additional details concerning this treatment, as well information on the positioning of remains, the grave goods, and the site in general, among *address for correspondence: joel d. irish, department of anthropology, p.o. box 757720, university of alaska fairbanks, fairbanks, ak 99775-7720, u.s.a. e-mail: ffjdi@uaf.edu an artificial human tooth from the neolithic cemetery at gebel ramlah, egypt joel d. irish*, przemyslaw bobrowski**, michal kobusiewicz**, jacek kabaciski**, and romuald schild*** *department of anthropology, university of alaska fairbanks, fairbanks, ak 99775 **institute of archaeology and ethnology, polish academy of sciences, 60-814 poznan, poland ***institute of archaeology and ethnology, polish academy of sciences, 00-140 warsaw, poland abstract excavations at the gebel ramlah cemetery, in upper egypt’s western desert, have provided numerous data concerning mortuary practices of the local final neolithic period populace. previous articles have chronicled treatment of disturbed inhumations, in which great care had been taken to recover and rebury all grave goods and skeletal elements including, most notably, dental remains. in several cases, the neolithic gravediggers apparently went so far as to reinsert, or to in other ways reincorporate, teeth that had fallen from their alveoli during handling. this report describes and interprets a new find, i.e., an anatomically accurate, life-size shell carving of a human incisor, that provides additional insight into the apparent importance of teeth to these desert people. dental anthropology 2004;17(1): 28-31. others (paleodemography, geologic information, etc.), are presented in irish et al. (2003), schild et al. (2002), and kobusiewicz et al. (n.d.). in 2003 the remaining burial concentrations were excavated. both also date to the final neolithic. during the course of fieldwork, two finds were made that provide additional evidence concerning the apparent importance of teeth to the local inhabitants. one, again, involves deliberate dental repositioning during the mortuary process; it is detailed elsewhere (irish et fig. 1. location of gebel ramlah. 28 29 al., n.d.). the other find, a shell fragment carved in the shape of a human tooth, is discussed here. the carved tooth during archaeological reconnaissance of the gebel ramlah cemetery, the second author discovered a small, purposefully-carved object located approximately equidistant to the three burial concentrations. this object was recovered from the desert surface, so its original, exact provenience is unknown. however, because it was found near bone fragments and artifacts analogous to those within the recovered final neolithic burials, it is likely contemporary. because of deflation, only those skeletons and grave goods that had been deeply buried remain in situ. a neolithic date is also inferred because no remains affiliated with other cultural/temporal periods were observed at the cemetery. the material from which the object was carved is shell. although the species is unknown, it appears to have been a large mollusk—which is more indicative of a salt-, rather than freshwater origin. thus, it may be derived from the red sea; several identifiable shells from this water source were found within intact burials. although other interpretations are possible (e.g., miniphallus?), it is almost certainly a life size rendition of a human maxillary incisor—specifically, a left central or perhaps lateral tooth. as evident in figures 2 through 5, the object’s “morphology” closely corresponds to this determination. everything from an incisor’s large, pointed single root, to its constricted neck and straight incisal edge are skillfully rendered. moreover, an indication of slight shoveling is detectable on what would be the object’s lingual surface (fig. 2). the lingual and labial (fig. 4) aspects of the “crown” are similar in appearance to that of a left central incisor. however, the occlusal view (fig. 5) is suggestive of a more asymmetrical left lateral incisor. indeed, mesiodistal and buccolingual measurements (using the method of moorrees, 1957) taken of the object’s “crown,” 7.7 and fig. 2. lingual view of the carved shell tooth. note indication of slight shoveling. tick marks on the margins are 1 millimeter intervals. fig. 3. mesial view of the carved shell tooth. tick marks on the margins are 1 millimeter intervals. fig. 4. labial view of the carved shell tooth. tick marks on the margins are 1 millimeter intervals. fig. 5. occlusal view of the carved shell tooth. tick marks on the margins are 1 millimeter intervals. artificial neolithic tooth 30 31 7.1 mm respectively, are close to that of mean diameters obtained from actual gebel ramlah male lateral incisors. these and other values (i.e., males, females, sexes pooled) for both maxillary central and lateral incisors are presented in table 1 for comparison. although not measured in the actual gebel ramlah teeth, the object’s “crown” height (7.2 mm), “root” length (15.3 mm), and overall length (22.5 mm) are well within the normal range of variation for human maxillary incisors (e.g., lavelle, 1968; personal observations by first author). because the carved tooth was not recovered in situ, its intended purpose is difficult to ascertain. still, it is plausible that it might fit into one of two broad functional categories, i.e., decorative object or surrogate human incisor. with reference to the first category, the tooth may have been an objet d’art, and/or was meant to be worn as jewelry. shell (as well as ivory, bone, and stone) bracelets, rings, and bead necklaces were found within the intact burials. yet, if it was part of a necklace, or in some other way intended to be worn, it would probably exhibit a hole to facilitate attachment—in the same manner that all of the aforementioned beads were delicately drilled. another possibility is that the tooth was an amulet. as described by bonner (1950) and reviewed by becker (1999), such amulets were often found in more recent egyptian burials. it is reported that these “votive objects and other types of charms . . . were commonly placed [fittingly] in the mouths of egyptian mummies” (per jonckheere, 1958, as quoted in becker, 1999:22). the carved tooth may represent a neolithic example of this later, more widespread practice. because the tooth is, more or less, anatomically accurate in size and appearance, there may be another possibility regarding its function. perhaps it was intended as a replacement for an actual human incisor. the egyptians are documented to have practiced basic dentistry by at least 2900 bc (perine, 1883, as quoted in becker, 1999; ring, 1985). more to the point, there are reports that they may have employed false teeth or prostheses (puech, 1995; ring, 1985); later mediterranean area populations (e.g., phoenicians, etruscans) certainly did (ring, 1985; becker, 1994a, 1996; teschler-nicola et al., 1998). however, as demonstrated by becker (1999: 20) (but see puech, 1995 for another view), there is “no evidence that dental prostheses were made before 630 bc or that they were fashioned in egypt or even present there until after 400 bc.” to further dissuade any idea that the tooth was a prosthesis, it has been shown that all examples of ancient false teeth are limited to the crowns only. in order for the present shell tooth (which includes the root) to be employed, it would have had to be implanted into an alveolus. dental implantation is a relatively recent invention, having first been clinically introduced in 1918 (ring, 1985); to date, no irrefutable ancient examples have been documented (see becker, 1994b, 1999). although it seems unlikely that the shell incisor served in a functional masticatory capacity, it may still have been intended to take the place of an actual human tooth. that is, perhaps it was inserted into the alveolus of an incisor lost postmortem. as noted above and elsewhere (irish et al., 2003, n.d.), extreme care was taken by the neolithic inhabitants during reburial of disturbed remains. such care included collection and, in some cases, reinsertion of loose teeth. perhaps the shell tooth was fashioned to replace the misplaced incisor of an individual disturbed by a later burial. after all, it does seem that the intent at gebel ramlah was to “… return these [disturbed] individuals to the soil in as complete of a state as possible” (irish et al., 2003: 281). in what may be deemed analogous treatment, two sets of more recent, old kingdom (ca. 2500 bc) remains from giza and el qatta in lower egypt, exhibit apparent post-mortem insertion of several teeth during the mummification process; however, in these cases actual human teeth, bound together with gold wire, were employed (see junker, 1914; harris et al., 1975; ring, 1985; puech, 1995). as stated by ring (1985:36), in accordance with junker’s (1914) own observations (and similar to that noted above), this treatment was table 1. measurements of carved shell tooth compared to mean crown diameters of maxillary incisors in the gebel ramlah (gr) skeletal sample. mesiodistal buccolingual specimen or sample dimension dimension shell tooth 7.7 mm 7.1 mm gr maxillary central incisors sexes pooled1 8.91 7.36 (n=22) (n=23) males only 9.13 7.80 (n=6) (n=6) females only 8.78 7.20 (n=12) (n=13) gr maxillary lateral incisors sexes pooled 6.97 6.74 (n=20) (n=21) males only 7.60 7.06 (n=6) (n=5) females only 6.72 6.70 (n=11) (n=12) 1gebel ramlah is coded gr. sexes pooled samples include individuals of indeterminate sex. j.d. irish et al. 30 31artificial neolithic tooth apparently done to “… inter a corpse in as complete a state as possible, for they [the egyptians] firmly believed that the body must be kept intact to house the soul in the afterworld.” the only other documented pre-modern example that may serve as a corollary for the neolithic tooth’s postmortem functional interpretation comes from honduras. an ad 600 mayan mandible from the ulúa valley contains three artificial teeth, also carved from shell, that were inserted into the incisor alveoli (ring, 1985). conclusion the actual purpose of the carved shell tooth is, of course, conjectural and will likely never be conclusively determined. yet, whether decorative or functional, the fact that the time was taken to carve such an anatomically accurate rendering suggests that teeth may have played a relatively important role in everyday life, or death. moreover, although small, it and other better documented finds (irish et al., 2003, n.d.) continue to provide insight into egyptian neolithic mortuary practices, and help add a measure of humanness to these desert folk beyond that ordinarily encountered in an archaeological setting. acknowledgments our gratitude is extended to the geological survey of egypt and the supreme council of antiquities. we also thank dr. fred wendorf, southern methodist university, and ms. heba baset, antiquities inspector, abu simbel office, egypt. fieldwork was financed by the state committee of scientific research through the institute of archaeology and ethnology, polish academy of sciences. a portion of the travel funding for the first author was made possible through a national science foundation grant (bcs-0119754) awarded to dr. jerome rose, university of arkansas. literature cited becker mj. 1994a. etruscan gold dental appliances: origins and functions as indicated by an example form orvieto in the danish national museum. dental anthropology newsletter 8:2-8. becker mj. 1994b. spurious “examples” of ancient dental implants or appliances. dental anthropology newsletter 9:5-10. becker mj. 1996. an unusual etruscan gold dental appliance from poggio gaiella, italy. dental anthropology newsletter 10:10-16. becker mj. 1999. ancient “dental implants”: a recently proposed example from france evaluated with other spurious examples. int j oral maxillofacial implants 14:19-29. bonner c. 1950. studies in magical amulets, chiefly graeco-egyptian. ann arbor: university of michigan press. harris je, iskander z, farid s. 1975. restorative dentistry in ancient egypt: an archaeological fact. j michigan dent assoc 57:401-404. irish jd, kobusiewicz m, schild r, wendorf f. 2003. neolithic tooth replacement in two secondary burials from southern egypt. j archaeol sci 30:281285. irish jd, kobusiewicz m, kabaciski j, schild r. n.d. two additional egyptian neolithic burials exhibiting unusual mortuary treatment of teeth. j int osteoarch (under review). junker h. 1914. expedition der weiner akademie 1914 auf dem friedhof von gizeh. vorbericht. kobusiewicz m, kabaciski j, schild r, irish j, wendorf f. n.d. a late neolithic cemetery at gebel ramlah playa. archaeology (in press). lavelle clb. 1968. anglo-saxon and modern british teeth. j dent res 47:811-815. moorrees cfa. 1957. the aleut dentition: a correlative study of dental characteristics in an eskimoid people. cambridge: harvard university press. puech pf. 1995. dentistry in ancient egypt: junker’s teeth. dental anthropology newsletter 10:5-7. ring me. 1985. dentistry: an illustrated history. new york: harry n. abrams, inc., publishers. schild r, kobusiewicz m, wendorf f, irish jd, kabaciωski j, królik h. 2002. gebel ramlah playa. in: lenssen-erz t, tegtmeier u, kröpelin s, editors. tides of the desert: contributions to the archaeology and environmental history of africa in honour of rudolph kuper. 14 africa praehistorica, monographs on african archaeology and environment. cologne: heinrich-barth institut, university of cologne, p 117123. teschler-nicola m, kneissel m, brandstätter, prossinger h. 1998. a recently discovered etruscan dental bridgework. in: alt kw, rösing fw, teschler-nicola m, editors. dental anthropology: fundamentals, limits, and prospects. new york: springer, p 57-68. wendorf f, schild r. 1999. introduction. in: nelson k, editor. archaeology manual: archaeological techniques in saharan archaeology. prepared for the institute of international education, subcontract no. 99-048, p 1-14. wendorf f, schild r. 2001. introduction. in: wendorf f, schild r, editors. holocene settlements in the egyptian sahara. vol. 1, the archaeology of nabta playa. new york: kluwer academic/plenum press, p 1-10. wendorf f, schild r (assemblers), close ae, editor. 1984. cattle keepers of the eastern sahara: the neolithic of bir kiseiba. dallas: southern methodist university. correia and pina 2002.3 18 19 the great number of works published with emphasis on this dental trait reflects its importance in dental morphology. the tubercle of carabelli is to dental morphology what the abo blood group system is to serology (scott and turner, 2000). this morphological trait was first described in 1841, by georg carabelli edlen von lunkaszprie (johnson, 1999). however, other authors indicate that 1842 was the date for the first reference of this dental structure (kraus, 1959; bang, 1972; mizoguchi, 1993; woelfel, 1997). georg carabelli (1787-1842), was an hungarian syphilologist (syphilis then being rampant in hungary and elsewhere) and dermatologist (hoffman, 1968; della serra, 1976). carabelli also was a professor of dental surgery in the petrograd academy (mizoguchi, 1993) and was court dentist to the austrian emperor franz (johnson, 1999). other monographs on syphilis, for example sabourad (1917), likewise claim that this dental characteristic is a pathognomonic sign of hereditary syphilis (corrêa, 1921; campbell, 1925; della serra, 1976; diamond [cited by hanke, 1987]). this fact explains the designation of tubercle of carabelli as the “sign of sabouraud.” however, authors like cruet, jeanselm, mozer, chenet, bardoin, de granda, gallipe and mantoux did not agree with this theory (campbell, 1925; della serra, 1976). nomenclature numerous synonyms have been used to refer to this dental trait. we encountered the designations of ectocone of chardin, ectocone of trihland, pericone of stehlin (ferreira, 1996), tuberculum anomalum, fifth lobe, supplementary cusp, fifth tubercle (proposed by cruet after descriptions by malassez and magitot [della serra, 1976]), accessory cusp, mesiolingual elevation or prominence, fifth cusp, tuberculum carabelli, carabelli’s anomaly, tubercle and cusp of carabelli (introduced by sömmerling [cited in dokládal, 1983] in honor of carabelli’s discovery), protuberance of carabelli, tubercle of carabelli: a review andré correia and carla pina faculty of dental medicine, university of porto. rua dr. manuel pereira da silva, 4200 porto, portugal abstract the tubercle of carabelli is an important morphological characteristic in the studies of dental morphology and forensic medicine. this trait has been used as an anthropological measure. the purpose of this work is to make a review of the information available about this dental characteristic. its morphology, genetic characteristics and frequency are discussed in this article. editor’s note: mr. correia and ms. pina’s paper was awarded honorable mention for 2001 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. carabelli’s complex, polymorphism of carabelli (mizogushi, 1993), tuberculus anomalus (used by georg carabelli edlen von lunkaszprie [campbell, 1925]), mesiolingual tubercle, paramolar tubercle, odd tubercle, and atrophied cusp (hanke, 1987). functionally, terms like carabelli’s cusp, fifth cusp, atrophied cusp, supplementary cusp and accessory cusp are incorrect given their position on the lingual side of the crown, which is about 2 mm lower than the occlusal level (fig. 1b) (woelfel, 1997). in the present study, the term carabelli’s tubercle is used to designate this morphological characteristic. during tooth odontogenesis, some cells of the inner enamel epithelium of the crown base (zona cingularis) retain a proliferative capacity. the development in this region of supernumerary cusps and styles is easily understood, as for example, the tubercle of carabelli (abrams, 1992; pinkerton, 1999; scott and turner, 2000). however, in case of an absence of development of a lingual cingulum, this region may or may not form a carabelli groove (abrams, 1992). classification in contrast to the stability of its position on the molar, this trait presents various forms, which makes its pattern difficult to establish. initially, references to this characteristic only considered the presence-and-absence of the tubercular and lobular forms (nominal scale). andré correia and carla pina 18 19 however, batujeff (cited in kraus, 1959) considered pits and grooves to be manifestations of this feature. this perspective has been supported by other investigators, like dietz (1944) and della serra (1951). dahlberg (cited in scott and turner, 2000) developed an ordinal scale with eight grades, from trait absence (0) up to a large tubercle (7). all the grades formed a continuum, varying in the degree of expression, as in the ordinal grades developed by mizoguchi (1993). perhaps because of the variety of classifications described in the literature, it is difficult to find precise morphological criteria that permit objective comparisons among studies. using the classification of dietz (1944), we have compiled the data presented in table 1. population frequencies the tubercle of carabelli is a phylogenetically ancient characteristic (pereira, 1995). jeanselm and de granda (cited in della serra, 1976) documented the presence of this tubercle in skulls of all eras, the first author reported trait from the remains of adventicious denticulus which was a lemur. it also has been reported in specimens of pithecanthropus sp. and in other anthropoids (corrêa, 1921). gregory (cited in campbell, 1925) demonstrated the importance of the tubercle of carabelli in the structural and phylogenetic relationships between primitive and more recent anthropoids and hominoids. schwartz et al. (1998) studied the tubercle of carabelli in the australopithecus (a. africans and p. robustus) and de terra (cited in corrêa, 1921) considered this dental characteristic as a sign of civilized races, of which the krapina man was used as an example. from an evolutionary perspective, the tubercle of carabelli tends to disappear in concert with reduction of the hypocone (fig. 1a), resulting in simplification of the occlusal surface (reid et al., 1991; mizoguchi, 1993; hillson, 1996; tsai et al., 1996). from a functional point of view, the tubercle is a compensatory structure of evolution reducing the mesiodistal diameter of upper molars as a result of excessive biomechanical stress exerted on the first molar (mizoguchi, 1993; tsai et al., 1996). the difference in the expression of the carabelli’s tubercle in the primary and permanent dentitions is a decreased frequency but with an elevated proportion of the tubercular form in the permanent dentition. as an anthropological measure, the tubercle of carabelli, in conjunction with other morphological traits has been used for the evolutionary study of races (de castro, 1989; johnson, 1999; bailey, 2000). some characteristics of dental crowns were present or absent in various racial groups, with a great frequency table 1. frequency of different expressions of carabelli’s tubercle author(s) tubercle lobe groove pit campbell (1925) 5.0 5.0 90.0 - campbell (1925) 23.8 35.7 40.5 - cohen (cited in della serra, 1976) 17.4 --44.8 della serra (1976) 5.3 2.1 30.1 23.6 dietz (1944) 31.1 55.3 8.0 5.5 ferreira (cited in della serra, 1976) 29.2 -29.2 - ferreira (cited in della serra, 1976) 18.1 -33.3 - sharma (1983) 0.0 -5.8 -fig. 1. views of a maxillary molar showing (a) mesial, mesial-occlusal and occlusal aspects of a tooth without the carabelli trait, (b) relationship of the carabelli tubercle on the mesial-lingual crown aspect (with measurement of cusp height relative to the crown’s occlusal surface), (c) a mesial-occlusal view of a molar with carabelli’s lobule, and (d) a mesial-cclusal view with carabelli’s groove. (illustration by daniel m�ller, ma.) 20 21 that were viewed as identifying characteristics of these groups. for example, in caucasians the frequency of tubercle of carabelli is elevated, while the same was not true of the mongol and in the melanesian races where the tubercle can reach the size of the other cusps (kraus, 1959; abrams, 1992; tsai et al., 1996). consequently, the trait can be relevant for dental and racial identification (table 2). in studies where the presence or absence of tubercle of carabelli was quantified, the trait is found more commonly on the first molar. occurrence of the tubercle on the second molar only occurs when it is also encountered on the first molar (dietz, 1944). the differences in population frequency should be considered in terms of differential frequencies of genes regulating the velocity and duration of mitotic cell activity of the zona cingularis (kraus and jordan cited in scott and turner, 2000). at the beginning of the last century, g.v. black (cited in bailit, 1980) confirms that this dental trace “was hereditary, appearing regularly in children’s teeth, when it was present in the parent’s teeth. also it is found, in a modified way when it is present in only one progenitor.” kraus (1959), in his first analysis, suggested a model of simple autosomal transmission corroborated by other studies. he also considered, that the homozygous condition was responsible for a marked tubercle and that the heterozygous genotype determined the presence of small grooves, pits, tubercles or lobules (figs. 1c and 1d). much later, lee and goose (1972), townsend and brown (1981) and pinkerton et al. (1999) proposed a multifactorial model in which, in spite of a strong genetic contribution, the environmental factors contributed to the expression of the characteristic. the high bilateral expression of carabelli’s tubercle in twins (townsend and martin, 1992; pinkerton et al., 1999) and the high level of symmetry that has been found in various studies (dietz, 1944; scott, 1980) emphasize the importance of a genetic contribution to trait expression, without overlooking environmental factors. the results of studies by mizoguchi (1977), townsend (1981), kaul and prakash (1981), scott and potter (1983), tsai et al. (1996), and pinkerton et al. (1999) document the existence of sex dimorphism in the expression of the tubercle of carabelli, namely that there is greater prevalence in males. on the other hand, scott (1980), castro (1989) and tsai et al. (1996) did not report any significant difference between the sexes. summary the tubercle of carabelli is a morphological dental characteristic with relevance in anthropological and forensic studies. the study of its distribution table 2. frequency of carabelli’s tubercle on the maxillary first molar frequency author(s) samples (percentage) bang (1972) eskimos, alaska 42.7 campbell (1925) aboriginal australians 33.2 corrêa (1921) portuguese 13.5 della serra (1976) white australians 54.4 dietz (1944) american soldiers 72.3 dokládal (198.3) romanian 52.0 ferreira (cited in della serra, 1976) whites, brazil 58.4 ferreira (cited in della serra, 1976) negroes, brazil 51.4 hanke (1987) brazilian population 58.3 kaul (1981) jat, india (primary teeth) 79.8 kaul (1981) jat, india (permanent teeth) 61.9 reid (1991) kwengo 57.0 scott (1980) eskimos and aleuts 47.3 scott (1980) indians, asia 62.2 scott (1980) indians, american southwest 66.9 scott (1980) easter island 35.7 scott (1980) solomon islands 44.2 scott (1980) hawaiians 45.4 scott (1980) american white 85.0 scott (1980) bantu 73.1 scott (1980) bushmen 70.3 scott (1980) whites, south africa 74.9 scott et al. (1983) pima indians 74.0 20 21 and frequency among populations demonstrates its importance in the research of human evolution. the documentation in the literature regarding its frequencies has permitted the estimation of phylogenetic relationships between populations separated by geographic conditions. acknowledgements the authors gratefully acknowledge the support of professor américo afonso with respect to the elaboration of this article. references cited abrams l, jordan re and kraus bs. 1992. kraus dental anatomy and occlusion. st. louis: mosby year book, p 75, 76, 290, 342-346. bailey se. 2000. dental morphological affinities among late pleistocene and recent humans. dent anthropol 14:1-8. bang g, hasund a. 1972. morphological characteristics of the alaskan eskimo dentition. am j phys anthropol 37:35-40. de castro jmb. 1989. the carabelli trait in human prehistoric populations of the canary islands. hum biol 61:117-131. campbell td. 1925. dentition and palate of the australian aboriginal. adelaide: the hassel press. corrêa aam. 1921. notas morfológicas sobre os molares superiores nos portugueses. porto: departamento de antropologia da faculdade de ciências da universidade do porto, p 9-16. della serra o. 1976. anatomia dental. rio de janeiro: artes médicas, p 133-137. dietz vh. 1944. a common dental morphotropic factor, the carabelli cusp. j amer dent assoc 31:748-789. dokládal m. 198.3. incidence of the carabelli anomalous tubercle in romanies (gypsies). folia morphol 31:51-54. ferreira f, costa jp, figueira f. 1996. a cúspide de carabelli como característica identificativa. stoma lis 40:51-55. hanke ed, henke ll. 1987. contribuição ao estudo do tubérculo de carabelli e suas relações com a face oclusal do segundo molar superior. dens fase ii 2:19-22. hassanali j. 198.2. incidence of carabelli’s trait in kenyan africans and asians. am j phys anthropol 59:317-319. hillson s. 1996. dental anthropology. cambridge: cambridge university press. hoffman kf. 1968. georg carabelli (1787-1842). zahnarztl prax 19:60 (abstract). johnson c. 1999. hominid evolution, dental anthropology, and human variation. oral biology and the department of orthodontics, uic college of dentistry. http: //www.uic.edu/classes/osci/ osci590/ kaul v, prakash s. 1981. morphological features of jat dentition. am j phys anthropol 54:123-127. kolakowski d, harris ef, bailit hl. 1980. complex segregation analysis of carabelli’s trait. am j phys anthropol 53:301-308. kraus bs. 1959. occurrence of the carabelli trait in southwest ethnic groups. am j phys anthropol 17: 117-123. lee gtr, goose dh. 1972. the inheritance of dental traits in a chinese population in the united kingdom. j med genet 9:336-339. mizoguchi y. 1993. adaptative significance of the carabelli trait. bull natn sci mus, ser d (anthrop) 19:21-58. pereira a, afonso a. 1995. alterações dentárias em populações antigas. contribuição para o seu estudo. rev port est cir maxilofac 36:19-24. pinkerton s, townsend g, richards l, schwerdt w, dempsey p. 1999. expression of carabelli trait in both dentitions of australian twins. perspectives human biol 4:19-28. reid c, van reenen jf, groeneveld ht. 1991. tooth size and the carabelli trait. am j phys anthropol 84:427-432. schwartz gt, thackeray jf, reid c, van reenan jf. 1998. enamel thickness and the topography of the enamel-dentine junction in south african pliopleistocene hominids with special reference to the carabelli trait. j hum evol 35:523-542. scott gr. 1980. population variation of carabelli’s trait. hum biol 52:63-78. scott gr, potter rh, noss jf, dahlberg aa, dahlberg t. 1983. the dental morphology of pima indians. am j phys anthropol ;61:13-31. scott gr, turner cg. 2000. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. sharma jc. 1983. dental morphology and odontometry of the tibetan inmigrants. am j phys anthropol 61: 495-505. townsend gc, brown t. 1981. the carabelli trait in australian aboriginal dentition. arch oral biol 26: 809-814. townsend gc, martin ng. 1992. fitting genetic models to carabelli trait data in south australian twins. j dent res 71:403-409. tsai pl, hsu jw, lin lm, liu km. 1996. logistic analysis of the effects of shovel trait on carabelli’s trait in a mongoloid population. am j phys anthropol 100:523-530. woelfel jb, scheid rc. 1997. dental anatomy, its relevance to dentistry, 5th ed. baltimore: williams & wilkins, p 243. 66 book review dental functional morphology: how teeth work. by peter w. lucas. new york: cambridge university press, 2004. 372 pages, 7 chapters, 2 appendices. $130.00 £75.00 occasionally in science a novel treatment of a familiar subject opens new vistas for exploration and thought. this is the case with dental functional morphology by peter w. lucas. part dental anthropology and part physics, this book challenges long held paradigms regarding the morphology of mammalian teeth. viewed from the perspective that physical characteristics of food drive selection of tooth form, lucas presents a well thought argument revolving around how dental morphology has evolved in response to the fracture properties of food. the adage “if you don’t eat, you die” can be altered using lucas’ view to “if your teeth don’t efficiently fracture foods and reduce particle size to that which is of the ainu to the prehistoric jōmon. despite his use of sophisticated statistics, however, his conclusions savored more of preconceived notions than of anything that derived from the actual metric data. without actually using odontometric data to test the idea, he debunked the old suggestion that there was a “caucasoid” element in the ainu. as with so many japanese who want to believe that they are descended from the prehistoric inhabitants of the archipelago, he tried to push the idea that the jōmon played a role in the ancestry of the japanese which they did to a varying extent. he recognized the fact that most japanese looked more like mainland east asians than jōmon-ainu people, and he suggested, in the absence of archaeological support, that massive population movements from that mainland had been responsible. his estimate was that more than a million people moved from northeast asia to japan during the time between 300 bce and 700 ce, a guess that has made more than a few prehistorians uneasy and doubtful. in 1972 he returned to the university of tokyo as professor of anthropology in the school of science where he remained until reaching the mandatory retirement age of 60. starting in 1987, he began what was to be a lifelong affiliation with the international research center for japanese studies in kyoto. actually, he was one of the major figures involved in setting up that research center in the first place. in order to make the case to japanese prime minister nakasone for the establishment of that center, hanihara traveled to america in the spring of 1985 and visited a series of universities to gather expressions of support for the project. his efforts were highly successful, and this points out one of the most prominent aspects of kazuro hanihara. he was a marvelous organizer and administrator and was a successful chairman of a museum and department as well as a long series of committees. not only was he admirably well-organized, but he exuded a manifestation of graciousness and charm that clearly nurtured his success. hanihara was probably most known for his proposal of a “dual structure model for the population history of the japanese” first published in 1991. in this, he proposed that the prehistoric jōmon of japan were derived from southeast asia which he sometimes referred to as “south asia” although this did not mean the indian sub-continent as that designation has usually implied. he suggested that a mixture of jōmon and northeast asians gave rise to the ainu on the one hand and the modern japanese on the other. the difference between the two, he proposed, was the result of microevolution in situ. the jōmon themselves he regarded as qualifying as perfectly good “mongoloids” although this was not supported by any kind of metric demonstration. the idea that the ainu represent the continuity of the jōmon with a bit of input from eastern asia is indeed supported by an analysis of common variance, and the idea that the japanese largely represent the morphology of eastern asia tempered by a trace of jōmon form in increasing amounts the farther east one goes in the archipelago is also supported by the variance figures. however, the role of microevolution in leading to the ainu/japanese differentiation has no basis, and there is no evidence supporting a southeast asian locus of origin for the jōmon themselves. last but not least, kazuro hanihara was enormously helpful to visiting scholars who knew little or no japanese. whether he agreed with the interpretation of the results of their work or not, he was unfailingly gracious and supportive. he figured out bus and train schedules, helped people get to the right stations, he met planes, and made hotel reservations, and many more much appreciated acts of generosity and assistance. for those of us who counted him as a friend, his passing leaves a real sense of loss. c. loring brace museum of anthropology university of michigan ann arbor, mi, 48109 usa and noriko seguchi department of anthropology university of montana missoula, mt, 59812 usa 67 optimal for energy extraction, you die.” as this implies, this volume is really an exploration of the mechanics of eating from the perspective of how biological material is broken down so that as much energy as possible is derived from that which is ingested. here i will attempt to elucidate the main points that lucas brings forth and pique the reader’s interest enough that you will obtain a copy; although it is not an easy read, it is certainly thought provoking. the nine sections (seven chapters and two appendices) of dental functional morphology can be distilled into two groups, namely the core of chapters 4-6 and the periphery. the periphery sets up understanding of the core. chapters 1-3 present a good background to the anatomy and functions of mastication, chapter 7 provides insight into the evolution of mammalian teeth, and the appendices present an introduction to the mechanics of fracture in solids and the mechanical properties of teeth and foods. chapter 1, “how to get excited about teeth,” briefly outlines what lucas is up to and begins one thinking of food in terms of how it breaks into smaller particles through the forces of mastication. as stated on page 10 the aim of the book is to consider “the function of teeth in relation to the ingestion, chewing, and swallowing of food. it attempts to elucidate the principles that underlie the evolution of tooth shape and size and those mechanisms by which the dentition can be maintained.” the basic point is that teeth need to be viewed as anatomical structures in which selection for shape and size are a result of the physical properties of the material they come in contact with. ergo, how teeth deal with two aspects of food, the external physical attributes and the internal mechanical properties, influences the evolution of their structure. lucas puts this in context for the salient aspects of the book in stating, “the chance of hitting a food particle with the teeth is enhanced by making the tooth bigger, i.e. by changing tooth size. in contrast, the effects of the force that the tooth exerts on that particle depend on the contours of its working surface�i.e. on its tooth shape” (p. 12). chapters 2 and 3 offer very good review of the anatomy and function of the mouth, respectively. included in chapter 2 is an in depth overview of the microand macro-structures of the teeth and masticatory apparatus with excellent lateral head and neck drawings. the last lines of the chapter allow an introduction to lucas’ writing style, which is best described as ‘humorously quirky’ at times. this last section deals with the muscles of the neck, which he closes thusly, “however, humans have an habitual upright bipedal stance in which the head is balanced only by continuous active contraction of posterior neck muscles such as the longissimi. without this action, the head falls forward —such as when dozing over a book like this. that is enough about structure” (p. 54). chapter 3 is a very in depth treatment of the mechanisms of mastication. jaw movement, food particle breakdown, food movement in the mouth, the mechanics of swallowing, taste, and the role of saliva are all addressed. this chapter begins the process of getting the reader thinking about teeth as processors of organic matter and is a building block for lucas’ argument concerning tooth size and shape developed in the following chapters. in most books, appendices are sections that supplement the main text and are meant to be perused, or ignored, as the reader sees fit. that is not the case with appendix a. before delving into the core of the book, chapters 46, this is necessary reading. as a primer on mechanical properties and their measurement, appendix a covers material important to understanding the concepts lucas presents. he suggests the reader at least “skim” this section, i suggest that a careful reading is important particularly if your knowledge of the mechanics of fracture in solids is limited. pay particular attention to the sections explaining young’s modulus (e), a measurement of stiffness (elasticity) of materials, and derivations for r (toughness) and k ic (fracture toughness) as a comprehension of these and other formulae is important for following lucas’ logic trail. study of tooth shape (ch. 4), size (ch. 5), and wear (ch. 6) is integral to the study of dental anthropology. the importance of shape and size, in particular, transcends the relatively narrow confines of our specialty to encompass the much broader study of the evolution of terrestrial life forms. since, as we all know, teeth are the most often recovered portions of once living beings, paleospecies rise and fall based on characteristics relating to the size and shape of their teeth. therefore, a better understanding of possible selective forces impacting dental evolution will lead to a better understanding of evolution in general. these three chapters offer readers the opportunity to reevaluate what they think they know about the evolution of the dentition and gain new insight into the microevolutionary forces at play in the evolutionary give-and-take between the eaters and that which they eat. it is difficult to explain lucas’ exploration of the properties of food particle fracture and their effect on dental form without detailed description and the repetition of formulae that would expand this review beyond acceptable limits. the basic premise of chapter 4, tooth shape, is the assumption “that the shape of teeth is an evolved response for overcoming the toughening mechanisms inside foods that frustrate their fracture and that these mechanisms lie at the heart of the diversity of dental form” (p. 96). this focus on the complex structural properties of food is in direct response to the classic, simplistic, view of tooth function that lumps teeth into two broad, ill defined, categories; shearing and grinding. by understanding the true mechanics of fracture in solids, how cracks are initiated and progress, it becomes apparent that “shear” and “grinding” are not what is happening at all during 68 mastication. force, applied through the teeth by the muscles of mastication, initiates cracks that lead to fracture and thence, to reduction in size of solid organic matter. the geometry of this fracture (how easily and in what manner it fractures) is controlled by the food particles and not by the teeth since being structurally sound is selectively advantageous. understanding how foods prevent fracture is important for understanding tooth form. lucas spends what seems like a great deal of time discussing cusp shape (pointedness) and how this affects fracture propagation, cell toughness, and the fracture characteristics of various foods. however, in the end, one is left with a better understanding of how the structural characteristics of food can influence tooth shape so that structures such as marginal ridges are no longer perceived as accessory features of crown anatomy but as structures that facilitate fracture continuation. with tooth size, lucas prods us to view it as something whose variation is tied to the size of the entire orofacial complex, the size of which is, in turn, related to the size of the food that is put into it. stating that “the overriding philosophy is that physical properties of mammalian diets explain not only tooth size, but also the size of most orofacial structures” (p. 133), he proposes that tooth size should be scaled not to body size as in standard allometric analyses but to the size of the ‘food particles’ that they encounter. he finds that the size of the anterior teeth and that of the post-canine teeth are affected by different aspects of the diet. on the one hand, jaw and anterior tooth size scale to the size of food as it is put into the mouth while postcanine tooth size is related to external physical properties of the food and how it fractures. along the way lucas presents in-depth discussions of the effects of variation in food toughness and tooth size, how food intake speed impacts overall orofacial size, and the differential effects of herbivory and carnivory on structures of the mouth. lucas explores tooth wear by examining what actually causes it. from a mechanical standpoint tooth wear is the loss of small fragments from the body of the tooth, therefore, understanding how these fragments are removed is important. tooth-tooth wear (attrition) and food-tooth wear (abrasion) affect enamel and dentine in different ways resulting in different selective pressures on the structure of teeth. in this view, food-tooth wear impacts tooth size while enamel thickness responds to tooth-tooth wear. the pressures of food-tooth interactions are spread across the whole of the crown and vary from chew to chew. this impacts tooth size because the larger the tooth the more surface comes into contact with food which, in turn, increases the life of the tooth, impacting survival. in contrast, tooth-tooth wear occurs repeatedly, and under high pressure, at very specific points, particularly the cusp tips, resulting in selective response in enamel thickness. while lucas states that he “did not say much in this chapter” (p. 200), he does present a wide ranging discussion of tooth wear that includes several pages on the response of dentine, an area that is frequently overlooked. the concluding chapter is self described as “a chapter of ideas, mixing fact with suggestions that, although seemingly logical and based on the previous chapters, might require a lifetime’s work to substantiate in any detail” (p. 202). as speculative in nature as it is, this chapter is also a thorough overview at how teeth function and the evolution of the mammalian dentition in light of the emphasis on the fracture properties of food. the last 20, or so, pages deals with diet and human evolution, touching on several areas. an example or two will suffice. on page 238 lucas anticipates the discovery of homo floresiensis by suggesting that dental reduction, specifically tooth loss, could be tied to dental crowding brought on by dwarfing in small, isolated, mammalian populations. pages 243-244 cover the molarization of premolars where he ties this trait to the size of the food that is being eaten and postulates that hominids who possess molarized premolars have adapted to eating relatively small objects. in fact it seems that lucas relates everything in dental evolution to food toughness and particle size. for the most part this appears to work. however, when it comes to applying this theoretical line to dental reduction and the effects of cooking food on tooth size lucas completely ignores the possible impact agriculture and the resulting foods high in fermentable carbohydrates may have had in the selection for smaller, less complex, molars over the last 10,000 years. now for a succinct concluding paragraph. hopefully this review has given the reader a hint at the complexity and value of dental functional morphology. although “a little thick at times” (reviewer’s notes), if taken in the right dosage, with periods of contemplation liberally interspersed, one comes away with a new appreciation for the role food has played in the evolution of teeth. however technical the book may be at times, i think it can also become an important resource for professionals and as a starting point for discussion in graduate seminars. on a theoretical level most of what is proposed within this volume is well supported though it seems that lucas is, at times, so tied to food particle size and fracture properties that other, simpler, possibilities are overlooked. as in any book of this length there are several nit-picky things that i could address but i’ll only attack one. on page 149, line 4, in discussing characteristics of food lucas says “fleshy fruits are designed for feeding on by vertebrates because these animals can disperse their seeds effectively” (emphasis added). the darwinian in me recoils at the implications of some unseen hand working its magic in what is otherwise a fine evolutionary synthesis. in the end, whether or not one buys lucas’ premise that the evolution of the mammalian dentition is the result of adaptation to the mechanical properties of food this book is a valuable addition to the dental anthropology literature. review by greg c. nelson kennedy 1999.3 pg12.jpg pg13.jpg oyamada et al. 2000.2 pg7.jpg pg8.jpg pg9.jpg pg10.jpg pg11.jpg pg12.jpg pg13.jpg pg14.jpg bailey 2000.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg pg7.jpg pg8.jpg hattab et al. 2000.2 pg7.jpg pg8.jpg pg9.jpg pg10.jpg pg11.jpg pg12.jpg pg13.jpg chiu and donlon 2000.4 pg20.jpg pg21.jpg pg22.jpg pg23.jpg pg24.jpg pg25.jpg pg26.jpg pg27.jpg pg28.jpg pg29.jpg pg30.jpg pg31.jpg pg32.jpg pg33.jpg pg34.jpg pg35.jpg pg36.jpg pg37.jpg hughes et al. 2002.1 2 3 the shape of the dental arches has held the attention of physical anthroplogists and dentists since the beginning of the last century. many methods have been developed to describe dental arch morphology, ranging from simple geometric classifications (hrdlička, 1916), through combinations of linear dimensions (moorrees, 1959) to various complex curve-fitting procedures (lu, 1966; jones and richmond, 1989; kasai et al., 1995; battagel, 1996). the application of fourth-order polynomials of the form: y = a + bx + cx2 + dx3 +ex4 provides a number of advantages, the most significant being that the coefficients can be easily interpreted (richards et al., 1990). the second (x2 or quadratic) and fourth (x4 or quartic) terms describe the arch shape while the first (x1 or linear) and third (x3 or cubic) terms describe asymmetry. lu (1966) drew attention to the inter-dependence of coefficients of simple polynomials. the sum of squares associated with the k coefficients cannot be partitioned into k parts, each attributable to a single degree of freedom. consequently, it is not possible to assign accurate values to the relative contributions of symmetry and asymmetry to overall arch shape. the partition can be achieved, however, by using orthogonal polynomials (kendall, 1959). lu (1966) presented the first detailed account of fitting orthogonal polynomials to arch data. unfortunately, although the theory for equally-spaced x-coordinates was sound, abstract there have been numerous attempts to quantify the shape of the dental arch mathematically, with orthogonal polynomial curves providing a robust and versatile method for quantifying variation in both shape and asymmetry. lu (1966) first presented the theoretical basis for fitting orthogonal polynomials to lu’s worked example contained some mathematical errors. furthermore, the extrapolation to non-equally spaced data was flawed. kendall (1959) provided the correct general parameterization for unequally-spaced data, and this was further simplified to a recursive method by robson (1959). the aim of the current paper is to address the errors within lu’s orginal paper, and to present a valid extrapolation of his work to unequallyspaced arch data for use in quantitative assessments of arch form. results and discussion the theoretical workings presented on pages 10581062 of lu’s original paper are substantially correct, with one small exception, and it would be inappropriate to reproduce this section in great detail. we urge those readers who are interested in lu’s adaptation of orthogonal theory that produces a partition of arch shape variance for equally-spaced data to examine the original paper, noting that the calculation for the sums of squares for the intercept of the orthogonal regression on page 1059 reads: ss = y n 2 ( )b0 0ξ ∑ when it should instead read: ss = y n ( )b0 0 2 ξ ∑( ) theoretically, lu’s concept cannot be faulted. however, the application of the theory was flawed, particularly in the use of published orthogonal polynomial tables for equally-spaced data (fisher and yates, 1957), leading to biased estimates of orthogonal coefficients. in the next section of this paper we reproduce verbatim the worked example from lu’s original paper form, symmetry and asymmetry of the dental arch: orthogonal analysis revisited toby hughes, lindsay richards, and grant townsend dental school, the university of adelaide, south australia, 5005. editor’s note: lu’s paper (1966) has been cited many times in the dental literature, but researchers have been confused by the nature of the analysis (orthogonal regression is not the same as conventional regression analysis) and most biologists and clinicians have been unable to “break-through” lu’s mathematics, particularly since there are several key errors in the paper. toby hughes and his colleagues were invited to submit this paper to facilitate the understanding and application of this useful analytic method. correspondence to: toby hughes, level 6 dental school, university of adelaide university, australia 5005 e-mail: toby.hughes@adelaide.edu.au arch shape data. whilst theoretically sound, lu’s original paper contained several arithmetic errors and a number of incorrect assumptions. in this paper we present corrections for these errors and extrapolate the theory to unequally-spaced arch shape data using a simple recursive procedure first developed by robson (1959). 4 5 although the curve-fitting technique is well known in statistical circles, it is thought that the intended audience of this paper might not be as familiar, and for this reason the sample is explained in considerable detail. the arch width is divided into 14 equidistant intervals defined by 15 points. we have the following observed data: x (arch base): -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7 y (arch height): 27.7, 20.1, 13.9, 9.4, 6.1, 3.4, 1.4, 0, 0.3, 1.3, 3.2, 6.3, 11.0, 18.2, 29.0 the computations are illustrated in table 1. ∑yξ 1 = 43.2 c ∑ξ 1 2 = 280 ∑yξ 2 = 6932.2 a ∑ξ 2 2 = 37,128 a ∑yξ 3 = -684.4 a ∑ξ 3 2 = 39,780 a ∑yξ 4 = -105,958.6 ab ∑ξ 4 2 = 6,466,460 ab an illustrative example for equally-spaced arch shape data (boxed text, page 4) from lu’s page 1062 onwards, important errors are shown in bold, and footnotes (listed below) to the text contain explanations and appropriate corrections. a ξi represents a polynomial of degree i in x (i.e. ξi = ϕ i (x j ) ). the original table from fisher and yates (1957) specifies a series of pre-multipliers (λ in ) for ξ 1 -ξ 4 in footnotes beneath the table. following fisher (1921), these arbitrary constants are determined conveniently so that ξ i is an integer for all j = 1, 2, ..., n. they were not referenced in lu’s paper, and his failure to apply them in subsequent calculations resulted in substantial errors throughout the remainder of the worked example. b this value was incorrectly signed as negative (-) in lu’s paper resulting in incorrect values for ∑yξ 4 and ∑ξ 4 2. c whilst lu’s use of sums and differences is arithmetically correct, we feel it adds unneccesary complexity to the calculations. indeed, in the one series of calculations where the pre-multiplier was 1 and in which lu’s figures should have been correct, the sign of ∑yξ 1 was incorrectly reported as positive (+), presumably due to the incorrect summing of the cross-products of the differences. it is preferable to simply list the full table and obtain the crossproducts directly. correct values for ∑yξ i and ∑ξ i 2 are as follows: ∑yξ 1 = -43.2 ∑ξ 1 2 = 280 ∑yξ 2 = 2,310.7 ∑ξ 2 2 = 4,125 ∑yξ 3 = 821.3 ∑ξ 3 2 = 57,283 ∑yξ 4 = 2,590.2 ∑ξ 4 2 = 760,139 due to the calculational errors noted above plus a number of subsequent arithmetic and typographical errors, the remainder of the worked example was substantially incorrect. the correct parameterization with the associated partition of variation (table 2) is presented below: ∑y2 = 2848.55 ∑y =151.3 n = 15 ∑yξ 1 = -43.2 ∑yξ 2 = 2,310.7 ∑yξ 3 = 821.3 ∑yξ 4 = 2,590.2 explanatory notes from observed data, we compute ∑y2 and ∑y. 2. column 1 is obtained by adding the y values pairwised from the centre, e.g. 1.4 + 0.3 = 1.7; 3.4 + 1.3 = 4.7, etc.c 3. column 2 is obtained by subtracting the y value corresponding to x from the y value corresponding to –x, e.g. 1.4 – 0.3 = 1.1; 3.4 – 1.3 = 2.1, etc.c 4. columns 3, 4, 5 and 6 are obtained from the orthogonal polynomial tablesa (fisher and yates, 1957) with n = 15. the ∑ξ i 2 are also obtainable from this table. these values are only listed for the upper half of the entire polynomial.c for evenpowered ξ the omitted half are duplicates of the exhibited half; for odd-powered ξ the omitted half are numerically the same values as the exhibited half, except with the signs reversed. 5. to obtain ∑yξ 1 and ∑yξ 3 we obtain the sum of cross products of the differences (column 2) with column 3 and column 5 respectively.c 6. to obtain ∑yξ 2 and ∑ξ 4 , we obtain the sum of cross products of the sum (column 1) with column 4 and column 6, respectively.c orthogonal analysis revisited 4 5 b = y n = 151.3 15 =10.08670 ∑ b = y = -43.2 280 =-0.15431 1 1 2 ξ ξ ∑ ∑ b = y = 2310.7 4125 =0.56022 2 2 ξ ξ 2∑ ∑ b = y = 821.3 57283 =0.1433 3 2 ξ ξ 3∑ ∑ b = y = 2590.2 760139 =0.00344 4 2 ξ ξ 4∑ ∑ ss (b 1 ξ 1 ) = b 1 ∑yξ 1 = (-0.1543)(-43.2) = 6.67 ss (b 2 ξ 2 ) = b 2 ∑yξ 2 = (0.5602)(2310.7) = 1294.45 ss (b 3 ξ 3 ) = b 3 ∑yξ 3 = (0.0143)(821.3) = 11.74 ss (b 4 ξ 4 ) = b 4 ∑yξ 4 = (0.0034)(2590.2) = 8.81 ss (b 0 ξ 0 ) = b 0 ∑y = (10.0867)(151.3) = 1526.12 ss (total) = ∑y2 – ss (b 0 ) = 2848.55 – 1526.12 = 1322.43 total ss explainable by regression: r = 1322.43-0.76 1322.43 =0.99972 index of total symmetry: a= v +v v +v +v +v x1002 4 1 2 3 4 = 1303.26 132167 x 100 = 98.31% index of total asymmetry: b = 100 a = 1.69% index of taperedness: a = v v +v x 1002 2 2 4 = 1294.45 1303.26 x 100 = 99.32% index of squaredness: a 4 = 100 a 2 = 0.68% index of lopsidedness: orthogonal analysis revisited sum difference ξ 1 a ξ 2 a ξ 3 a ξ 4 a 0.0 0.0 0 -56 0 756 1.7 1.1 1 -53 -27 621 4.7 2.1 2 -44 -49 251 9.3 2.9 3 -29 -61 -249 15.7 3.1 4 -8 -58 -704 24.9 2.9 5 19 -35 -869 38.3 1.9 6 52 13 -429 56.7 -1.3 7 91 91 -1001b table 1. computational table for fitting a fourth order orthodongal polynomial to 15 points source d.f. sum of squares total 14 1322.43 symmetry (b 2 + b 4 ) 2 1303.26 quadratic (b 2 ) 1 1294.45 . . . v 2 quartic (b 4 ) 1 8.81 . . . v 4 asymmetry (b 1 + b 3 ) 2 18.41 linear (b 1 ) 1 6.67 . . . v 1 cubic (b 3 ) 1 11.74 . . . v 3 remainder 10 0.76 table 2. partition of variation 6 7 b = v v +v x 100 = 6.67 18.41 = 36.26%1 1 1 3 index of tiltedness: b 3 = 100 b 1 = 63.77% the procedure outlined above is suitable for data obtained at equidistant increments of x. however, on most occasions, investigators wish to define the dental arch in terms of specific anatomical landmarks. in such cases, the width distances of the arch may increase unequally and the use of tabulated orthogonal coefficients is invalid. lu’s (1966) analytical extension to unequally-spaced data was flawed, irrespective of the numerous typographical errors that were present in the derivation. lu noted that in computing the following simple polynomial regressions: y = a + b 1 x y = a’ + b’ 1 x + b 2 x2 y = a’’ + b’’ 1 x + b’ 2 x2 + b 3 x3 y = a’’’ + b’’’ 1 x + b’’ 2 x2 + b’ 3 x3 + b 4 x4 it can be shown that: y = a b 1 ϕ + b 2 ϕ2 + b 3 ϕ3 + b 4 ϕ4 fig. 1. graphical representation of cusp tip spacings used to define arch shape. x (arch base): -19.12, -17.68, -14.81, -11.63, -8.03, -2.20, 2.22, 9.41, 14.46, 17.38, 20.19, 21.54 y (arch height): 35.18, 31.78, 24.41, 18.28, 13.61, 11.80, 11.79, 13.77, 18.42, 24.43, 31.84, 35.75 fig. 2. arch shape described by an orthogonal fourth order polynomial, with antimeric points joined to illustrate the degree of asymmetry. where ϕ 1, ϕ 2 , ϕ 3 , and ϕ 4 are orthogonal polynomials and their coefficients are the last unprimed coefficients of each of the four equations respectively. however, this is only true in the case of equally-spaced data, a fact overlooked in the original paper. even were it appropriate for use on unequally-spaced data, the subsequent partition of variance that was presented (cited from ostle, 1958) was also incorrect, a fact which can be easily verified by application to the equally-spaced data from the same paper. kendall (1959) presented the analysis of equallyspaced x-values as a special case of the more general usage of orthogonal polynomials for all data-types. robson (1959) extended the analysis of non-equally spaced x-values by presenting a simple recursive procedure to estimate appropriate orthogonal polynomial equations. an alternative construction procedure, also recursive but requiring the solution of r linear equations for the construction of ∫ r (x i ) was described by grandage (1958). robson’s (1959) methodology is robust and efficient and remains the method of choice for both equallyand unequally-spaced arch data. for the full methodology, a detailed examination of the original paper is recommended. a simplified protocol appropriate for fitting a fourthtable 4. x and y values for the dental arch used in the illustrative example orthogonal analysis revisited 6 7 source d.f. sum of squares total 11 935.87 symmetry (b 2 +b 4 ) 2 932.19 quadratic (b 2 ) 1 918.21 ...v 2 quartic (b 4 ) 1 13.98 ...v 4 asymmetry (b 1 +b 3 ) 2 1.00 linear (b 1 ) 1 1.00 ...v 1 cubic (b 3 ) 1 0.00 ...v 3 residual 7 2.68 table 3. partition of variation order orthogonal polynomial to arch shape data, and the subsequent partition of variance (table 3) and derivation of shape-indices is presented below. the worked example uses data from a single arch (hughes et al., 2001) for illustrative purposes (fig. 1). the data are listed in table 4. ξ0 = 1 n ξ ξ ξ ξ ξ 1 0 0 0 2 = x0 x x x ∑ ∑∑ −( ) ξ ξ ξ ξ ξ ξ ξ ξ ξ 2 2 0 2 1 0 2 0 1 2 1 2 = x0 1x x x x x − − −( ) ∑∑ ∑∑∑ ξ ξ ξ ξ ξ ξ ξ ξ ξ ξ 3 3 0 3 1 2 3 2 0 3 0 1 3 = x0 1x x x x x x − − − − ∑∑∑ ξξ ξ ξ1 2 3 2 2 −( )∑∑∑∑ x ξ ξ ξ ξ ξ ξ ξ ξ ξ ξ 4 4 0 4 1 2 4 2 3 4 4 0 = x0 1x x x x x x − − − − ∑∑∑∑ 44 0 1 4 1 2 4 2 3 4 4 2 ξ ξ ξ ξ ξ ξ ξ− − −( )∑ ∑∑∑∑ x x x b 1 = ∑yξ 1 = 1.00 ss 1 = b 1 2 b 2 = ∑yξ 2 = 30.30 ss 2 = b 1 2 b 3 = ∑yξ 3 = 0.04 ss 3 = b 3 2 b 4 = ∑yξ 4 = 3.74 ss 4 = b 4 2 total ss = y y n = 935.87 2 ∑∑ ( )2 total ss explainable by regression: r = 935.87 2.68 935.87 = 1.002 shape indices can be calculated as outlined earlier. total symmetry = 99.89% is composed of taperedness (98.50%) plus squaredness (1.5%). total asymmetry = 0.11% is composed of lopsidedness (100.00%) plus tiltedness (0.00%). the relative magnitudes of these indices are illustrated in figure 2, which shows the fitted curve with connected antimeres. conclusion lu’s original 1966 paper remains of value for illustrating the utility of orthogonal polynomials in the analysis of arch shape data, and clearly the original theoretical considerations were of merit. unfortunately, the numerous mathematical errors contained within the paper make its application to real-world data misleading and inaccurate. the corrections outlined in the present paper should now enable researchers to carry out more accurate and reliable orthogonal analysis revisited 8 9 two interactive programs on cd: development of the tooth germ covers development of the tooth from initiation to formation of the root, not including development of the specific dental tissues. navigation is via a simple menu structure with 10 chronological stages copiously illustrated with diagrams, clinical photographs and histological material. development of the face, palate and tongue considerččs aspects of normal development of the neural crest, pharyngeal apparatus, face, palate and tongue and consequences of abnormal development, with a wide range of clinical examples. as well as providing many static images and animated diagrams, morphing techniques have been applied to scanning electron micrographs to provide movie sequences showing the structures actually changing. both programs include a quiz section. they run under windows 3.11 or later. a 486 ibm compatible pc with 8mb ram and approximately 20 mb free hard disk space is required. how to order: the price of these cds is us $40 each for an individual copy or us $180 each for a site licence. cheques should be made payable to gghb endowment fund 40-42 and sent to: dr. marie e. watt glasgow dental school 378 sauchiehall street glasgow g2 3jz u.k. quantitative assessments of dental arch form using the orthogonal polynomial approach. acknowledgements this study was supported by a grant from the national health and medical research council (nh & mrc) of australia. literature cited battagel jm. 1996. individualized catenary curves: their relationship to arch form and perimeter. br j orthod 23:21-28. fisher ra. 1921. studies in crop variation. i. an examination of the yield of dressed grain from broadbalk. j agric sci 11:107. fisher ra, yates f. 1957. statistical tables for biological, agricultural and medical research. new york: hafner. grandage a. 1958. orthogonal coefficients for unequal intervals. biometrics 14:287-289. hrdlička a. 1916. contribution to the anthropology of central and smith sound eskimos. ann pap am nat hist 5:177-285. hughes te, richards lc, townsend gc. 2001. dental arch forms in young australian twins. in: brook a, editor. dental morphology 2001. sheffield: sheffield academic press ltd, p 309-320. jones ml, richmond s. 1989. an assesment of the fit of a parabolic curve to preand post-treatment dental arches. br j orthod 16:85-93. kasai k, richards lc, townsend gc, kanazawa e, tadamasa i. 1995. fourier analysis of dental arch form in south australian twins. anthropol sci 103:39-48. kendall mg. 1959. the advanced theory of statistics, 3rd ed. vol. ii. new york: hafner. lu kh. 1966. an orthogonal analysis of the form, symmetry and asymmetry of the dental arch. arch oral biol 11:1057-1069. moorrees cfa. 1959. the dentition of the growing child. cambridge: harvard university press. ostle b. 1958. statistics in research. iowa: iowa state university press. richards lc, townsend gc, brown t, burgess vb. 1990. dental arch morphology in south australian twins. arch oral biol 35:983-989. robson ds. 1959. a simple method for constructing orthogonal polynomials when the independent variable is unequally spaced. biometrics 15:187-191. orthogonal analysis revisited interactive teaching programs on cd cucina et al. 2004.1 65 the presence of african individuals in the colonial town of campeche goes back to the 16th century ad when african slaves were brought in by the spanish colonizers as servants and workers (mallafe, 1973). their presence in the ancient colonial cemetery in the town’s main plaza (plaza principal) was initially suggested by a series of dental non-metric traits and particular dental decoration patterns, that were unknown to native mesoamericans (scott and turner, 1997; tiesler, 2001; tiesler and zabala, 2001). the cemetery surrounded the ancient church that was in use from the mid 16th century ad to the end of the 17th century, when it was replaced by campeche’s cathedral. the graveyard’s chronology was confirmed by maps of the colonial town and by a medallion, whose typology is known not to have updated the 1650s (coronel et al., 2001; deagan, 2002). the material evidence confirms the historical sources that report the presence of africans along with the arrival of the spaniards (mallafe, 1973). apparently, africans were employed as servants in the spanish households (zabala et al., 2003), as the production economy in the town of campeche had no need for hardwork slavery, as in plantations or mines. this study, which presents the preliminary results of an ongoing project on provenance in the maya area during precontact and contact times, addresses the issue provenance of african-born individuals from the colonial cemetery of campeche (mexico) by means of trace elements analysis andrea cucina1*, hector neff2, vera tiesler1 1facultad de ciencias antropológicas, universidad autónoma de yucatán 2 department of anthropology, california state university, long beach, ca (usa) universidad autónoma de yucatán, mérida, yucatán, méxico, 97000 *correspondence to: andrea cucina, facultad de ciencias antropológicas, universidad autónoma de yucatán, calle 76 n. 455 ll 41 y 43, col. centro 9700, mérida, yucatán. e-mail: cucina@tunku.uady.mx abstract the present study investigates the issue of foreign provenance of african individuals buried in the early colonial cemetery of campeche (mexico) using multiple trace elements analysis from the first permanent molar. it rests on the assumption that, like for strontium isotopes, the elemental pattern in the first molar reflects the hydro-geological environment the individual grew in. the individuals of african ethnicity were identified from their pattern of dental morphology. twenty-eight individuals were analyzed in this context, eight of them supposedly africans, while 15 were infants or early juveniles and five from the prehispanic site of xcambó in northern yucatán. the infants and juveniles were likely born in the area, thus serving as term of comparison for the |local” elemental pattern. the elements’ ppm concentrations of the 28 individuals were elaborated using principal components analysis. results tend to cluster the infants and some of the african individuals together, though the majority of the africans tend to group. one african individual in particular separates well from all the others. assuming that dietary components might interfere with the individuals’ distribution, only elements not related to diet were thus used, without different results from the previous analysis. indeed, the elements correlating high with the first two components are non-dietary. trace elements patterns indicate that some of the african individuals interred in the early colonial cemetery might have been born in other places, though we cannot infer on their place of origin, while others were probably born in the new world. dental anthropology 2004;17(3):65-69. of detecting the place of nativity of campeche’s ethnic africans. it assumes that trace element pattern from the enamel of the first molar reflects the environment the individuals were born in. for this reason, the persons who had been “imported” or had migrated from another area should present a pattern that differs from that of the local population (cucina et al., 2004). in this context, the african individuals’ pattern is compared to the one established from homologous teeth of infants recovered from the same site, resting on the assumption that babies buried in the cemetery were likely born in town or in its neighboring areas. materials and methods the sample analyzed in this context is part of the skeletal collection of 180 individuals unearthed during the 2000 archaeological salvage excavation in the plaza principal of the town of campeche, which is located long the coast of the gulf of mexico, in the northern part of the yucatan peninsula (fig. 1). at least 20 skeletons showed 66 67 a dental morphological pattern assignable to african ethnicity (scott and turner 1997; irish 1997; 1998). four of these individuals presented a pattern of dental mutilation unknown in the area during precolonial times (tiesler, 2001) and similar to those introduced by african slaves throughout the caribbean (ortner, 1966; handler et al., 1982; milner and larsen, 1991; crespo, 1992). the analysis was conducted on the first permanent molar of 28 individuals, eight of them showing african dental morphological patterns, 15 being infants and early juveniles that should be representative of the area. five additional specimens come from the precontact maya site of xcambó. the choice of the first permanent molar rests on its age of development and the likeliness that it reflects more than other teeth the hydro-geological environment in which the individuals grew up (molleson, 1988; burton et al., 2003; jones et al., 2003). the africans are listed in the fig. 1. geographical location of the town of campeche fig. 2. principal components analysis: distribution of the individuals along the first and second components using all the elements available (but calcium) listed in table 1. “a” labels the african individuals, “p” the autochthonous from campeche, “x” the individuals from the precontact, classic site of xcambó. graphs as “a” and a serial number ranging from 13 to 20. the campeche infants are labeled as “p” and a serial number from 1 to 15, while “xc” (from 1 to 5) represents the individuals from xcambó. teeth were sectioned longitudinally, and the inner layers of the “hidden enamel” (hillson, 1996) exposed and analyzed by means of laser-ablation using a new wave 213-nm laser and elements read by an icp perking elmer 6100 drc mass spectrometer. the elements’ intensity was then transformed into parts per million (ppm), and converted into its log values for multivariate analyses. results the elements’ intensity that was high enough to be read by the mass spectrometer was converted from ppm into logarithmic ones. excluding calcium, these elements have been employed to perform principal components statistical analyses. table 1 lists the elements’ components rotated matrix, while table 3 shows the same elements’ components for the non-dietary elements only. the elements with higher values for each component appear in bold. figure 2 shows the individuals’ bi-dimensional scatter plot for first versus second components using all the elements available, while figure 3 shows the same scatter plot after dietary elements were removed. a common distribution pattern emerges from all the graphs, despite the wide range of variability in their elemental composition. the individuals identified as africans tend to be more widely spread in all the graphs than the site’s infants and young adolescents (labeled as p). within the african group, some (a19 above all) constantly separate from the rest. interestingly, we obtained the same pattern when we used all the elements or only the non-dietary ones. fig. 3. principal components analysis: distribution of the individuals along the first and second components using only non-dietary elements listed in table 2. a. cucina et al. 66 67 discussion historical sources report the presence of african slaves in campeche since the arrival of the spanish (scholes, 1936; redondo, 1995). their presence in the catholic cemetery is not unusual, as they were converted to the catholic religion upon arrival (aguirre beltrán, 1994). therefore, we expect that the african population in the cemetery of the town’s plaza principal may be representative of persons born both in the old and in the new world. trace elements have been used to detect foreign provenance within archaeological samples (burton et al., 2003; jones et al., 2003), despite their broader range of variability and less stability when compared to stable isotopes. trace elements are subject to dietary and physiological influence, as well as diagenetic changes (sandford and weaver, 2000), which may affect the hydro-geological marks left by the environment during growth (molleson, 1988). interestingly the results from this study bestow similar patterns regardless whether all the elements or only the non-dietary elements were used in teeth. apparently, this indicates that neither diet nor diagenesis affect the elemental pattern from first molar’s hidden enamel. the elements that show higher correlation values with each component are not the “dietary” ones, and if diagenesis had altered the chemical composition, results should have been flattened and more homogeneity should have been found. the results indicate that some of the ethnic african individuals from campeche’s colonial cemetery may not have been born in the area, in particular the individual labeled as a19 and to a lesser extent a16, a20 and a15. previous analyses on other batches of trace elements readings (cucina, 2004; cucina et al., 2004) still indicated an african individuals’ distribution pattern almost independent from the native one. a16 and a15 showed a kind of dental decoration unknown in precolonial mesoamerica (tiesler, 2001) and apparently imported from the african continent. at this point of the analysis it appears that the decorated individuals were born outside campeche, although we cannot make specific 1 2 3 na23 0.089 0.501 -0.012 mg24 -0.222 0.756 -0.013 al27 0.093 0.818 0.189 si30 0.878 -0.159 0.074 k39 0.164 0.483 0.241 sc45 0.098 0.003 -0.032 ti47 0.101 0.448 0.364 v51 -0.255 -0.198 -0.100 cr52 0.820 -0.058 0.343 mn55 0.685 0.415 0.107 fe57 0.378 0.623 0.057 ni60 0.068 0.547 0.538 cu65 0.070 -0.017 0.868 zn66 -0.455 0.091 0.009 as75 -0.115 0.411 -0.011 rb85 0.571 0.261 0.583 sr88 0.000 0.102 0.217 zr90 0.258 0.238 0.737 sb121 -0.050 -0.322 -0.073 cs133 0.297 0.126 0.005 ba138 0.021 0.086 0.094 la139 0.153 0.657 0.279 ce140 0.568 0.023 0.398 gd158 0.765 0.284 0.323 dy164 0.186 0.026 -0.049 yb174 0.196 -0.027 0.061 lu175 0.571 0.623 0.071 hf180 -0.213 0.374 0.247 ta181 0.249 0.437 0.213 pb208 0.275 0.213 0.725 th232 0.720 0.130 -0.072 u238 0.068 0.136 0.460 table 1. matrix of rotated components of all the elements analyzed1 1varimax rotation converged in 20 iterations. values in bold indicate the elements. 1 2 3 al27 0.041 0.868 0.208 si30 0.910 -0.117 0.007 sc45 0.133 0.045 -0.045 ti47 0.043 0.638 0.391 v51 -0.252 -0.047 -0.075 cr52 0.845 0.092 0.296 ni60 0.013 0.538 0.647 cu65 0.056 0.017 0.925 as75 -0.084 0.603 -0.132 rb85 0.525 0.254 0.668 zr90 0.311 0.309 0.597 sb121 -0.105 -0.057 -0.009 cs133 0.178 0.302 0.131 la139 0.122 0.735 0.257 ce140 0.540 0.055 0.463 gd158 0.819 0.213 0.247 dy164 0.160 0.109 -0.001 yb174 0.195 0.045 0.083 lu175 0.532 0.672 0.042 hf180 -0.117 0.414 0.126 ta181 0.229 0.421 0.230 pb208 0.354 0.253 0.642 th232 0.689 0.076 0.016 u238 0.046 0.195 0.486 table 2. component’s rotated matrix of the non-dietary elements. varimax rotation converged in 7 iterations1 1values in bold indicate the elements. african provenance by trace elements 68 69 inferences on whether these individuals had undergone the process when still in their country of origin or whether this practice was introduced and performed in yucatán at least for a generation or two before disappearing. further analyses and confirmation of nativity from stable isotopes on the same individuals will help us better understand this complex multiethnic society in colonial times. in conclusion, trace elements provided promising results in detecting foreigners in archaeological samples. differently from previous studies that focused on one or two elements, this analysis uses a multi-elements approach. the application of laser ablation permits to spot-read the hidden enamel, limiting the effects of diagenesis. some individuals were not likely born in the area, although it is not yet possible to detect whether their place of origin was africa or somewhere in the caribbean or mesoamerica, for an african comparison pattern in not available, the exact date of death is unknown (no tombstone or parish record) and the time span the cemetery was in use encompasses two centuries. notwithstanding these limitations and the problems in obtaining consistent data due to calibration of the equipment, this analysis indicates that trace elements can find applications in studies of natality and migration patterns. acknowledgments the authors want to thank dr. p. zabala for sharing the historical information on campeche’s ethnic integration, the state of campeche and the inah campeche for institutional support. a special thanks goes to sachiko sakai for helping us with the laser. the research has been funded by promep grant n. 103.5/03/1125. literature cited aguirre beltrán g. 1994. el negro esclavo en nueva españa. la formación colonial, la medicina popular y otros ensayos. fondo de cultura económica, méxico: 110. burton jh, price td, cahue l, wright le. 2003. the use of barium and strontium abundances in human skeletal tissues to determine their geographic origins. international j osteoarch 13:88-95. coronel g, cortés g, osnaya k, cybele d, tiesler v, zabala p. 2001. prácticas funerarias e ideosincracia en la ciudad colonial de campeche. los investigadores de la cultura maya, 9:197-206. crespo torres e. 1992. primera evidencia de mutilación dentaria en una población negroide de puerto rico. revista salud y cultura, universidad de puerto rico, san juan, año 4, 1:95-105. cucina a. 2004. procedencia y estatus social de los africanos en la villa colonial de campeche: un estudio químico y antropológico preliminar. estudios de antropologia biologicas, 12 (in press). cucina a, neff h, tiesler v. 2004. detecting provenience of african-origin individuals in the colonial cemetery of campeche (yucatán): a new approach using trace elements and la-icp-ms. in: speakman rj, neff h, editors. applications of la-icp-ms in archaeology. albuquerque: university of new mexico press (in press). deagan k. 2002. artifacts of the spanish colonies of florida and the caribbean, 1500-1800. vol. 2: portable personal possessions. washington, dc: smithsonian institution. handler js, corruccini rs, mutaw rj. 1982. tooth mutilation in the caribbean: evidence from slave burial population in barbados. j hum evol 11:297313. hillson s. 1996. dental anthropology. cambridge: cambridge university press. irish jd. 1997. characteristic highand low-frequency dental traits in 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anthropol 25: 177-180. redondo b. 1995. negritud en campeche. de la conquista a nuestros días. in: martínez montiel lm, editor. presencia africana en méxico. méxico. consejo nacional para la cultura y las artes. p 353. sandford mk, weaver ds. 2000. trace element research in anthropology: new perspectives and challenges. in: katzenberg ma, saunders sr, editors. biological anthropology of the human skeleton. new york: wiley-liss, p 329-350. scholes fv. 1936. documentos para la historia de yucatán. 1550-1561. mérida. scott rg, turner ii cg. 1997. the anthropology of modern teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. a. cucina et al. 68 69 tiesler v. 2001. short report: new case of an african tooth decoration from colonial campeche, mexico. homo 52:277-282. tiesler v, zabala p. 2001. reflexiones sobre la composición poblacional del estado de salud y las condiciones de vida vigentes en la ciudad de campeche durante los siglos xvi y xvii. los investigadores de la cultura maya 9:197-206. zabala p, cucina a, tiesler v, neff h. 2003. la población africana en la villa colonial de campeche: un estudio interdisciplinario. los investigadores de la cultura maya, 12 (in press). african provenance by trace elements dental anthropology association celebrates its 20th meeting in celebration of its 20th meeting, the dental anthropology association is sponsoring a symposium at the 2005 american association of physical anthropologists meetings to be held in milwaukee, wisconsin. dental anthropology 20 years after: the state of the science will consist of 14 papers covering a wide range of topics germane to the anthropological study of teeth. organized and chaired by daa past president joel irish (alaska, fairbanks) and greg nelson (oregon) the symposium brings together a myriad of researchers for a welcome look at the relevance and breadth of dental anthropology as it stands in the middle of the first decade of the 21st century. the symposium is scheduled as session 9 on thursday afternoon april 7. this is fortuitous, as the symposium precedes the annual daa business meeting scheduled for thursday evening. we expect everyone to attend. in addition to the symposium, dental anthropology will be well represented at the 2005 aapa meetings with a podium session (session 3, thursday morning) and a poster session (session 26, saturday morning) scheduled. following is the symposium abstract and a list of authors and paper titles: dental anthropology 20 years after: the state of the science organizers and chairs: joel d. irish, university of alaska fairbanks, and greg c. nelson, university of oregon. commemorating the 20th anniversary meeting of the dental anthropology association, this symposium highlights recent research in the subfield that is illuminating issues of fundamental anthropological importance. using both established and innovative new methodological and technological approaches, scholars with interests ranging from the microto macroscopic levels of structure and expression present their latest findings on dental genetics, histology, growth and development, pathology, and morphometrics across a broad range of living and fossil human and non-human primate taxa. thus, unlike many symposia that focus on specific topics and/or regions, the unifying theme here is diversity. the intent is to assess the current state of the subfield, emphasize its insights into diverse anthropological questions, and explore its potential future directions. cosponsored by the dental anthropology association. leslea hlusko and michael c. mahaney. conceptualizing dental characters: implications from baboon quantitative genetic analyses. gary schwartz. the evolutionary history of growth and development: sorting through the evidence with a fine tooth-comb. helen liversidge. dental age revisited. debbie guatelli-steinberg. using perikymata to estimate the duration of growth disruptions in fossil hominin teeth. louise humphrey, christopher dean, and teresa jeffries. identification of the neonatal line using laicp-ms. mark teaford. insights from life’s little abrasions: dental microwear at middle-age. peter ungar and sarah taylor. dental topographic analysis: tooth wear and function. simon hillson. the current state of dental decay. brian hemphill. at what cost a full belly? an investigation of the seductive allure of sedentary horticulture in the great basin. kalpana agrawal and peter lucas. methods of ingestion and incisal designs. shara bailey. the place of neandertals in modern human evolution: intraand interspecific variation in occlusal dental morphology. charles fitzgerald and simon hillson. dental reduction in late pleistocene and early holocene hominids: alternative approaches to assessing tooth size. roberto macchiarelli and luca bondioli. virtual dentitions: touching the hidden evidence. discussants for the symposium: john luckas and edward harris. submitted by: greg c. nelson shah et al. 2005.1 37 crowding in the lower arch most commonly is seen in the anterior segment. the etiology of dental crowding seems to be multifactorial and tooth morphology has been suggested as an important component. no single factor has so far been demonstrated to be a major cause of anterior crowding. some workers have found a positive correlation between lower incisor and posterior tooth mesiodistal width (md) and lower arch crowding (peck and peck, 1972a,b; norderval et al., 1975; doris et al., 1981); others (mills, 1964; howe et al., 1983; radnzic, 1988) have failed to find evidence of such an association. there is coordinated development between different tooth types in the dental arch in size, such that subjects with larger mesiodistal dimensions of lower incisors may have larger tooth size elsewhere in the dental arch (harris and bailit, 1988). however, studies of lower incisor crowding and posterior tooth morphology have been limited to measuring only the mesiodistal width. therefore, the aim of this study was to investigate the relationship between lower incisor crowding and the occlusal surface area, buccolingual and mesiodistal dimensions of mandibular posterior teeth. materials and methods the sample consisted of dental casts of the mandibular teeth of 50 adult caucasians (25 males and 25 females). a computerised image analysis technique was used to analyse the dental casts (brook et al., 1998). the apparatus consisted in part of a 32-bit digital camera posterior tooth morphology and lower incisor crowding anwar a. shah*, claire elcock, and alan h. brook department of oral health and development, school of clinical dentistry, university of sheffield, united kingdom *correspondence to: anwar shah, department of oral health and development, school of clinical dentistry, university of sheffield, s10 2ta, united kingdom email: a.a.shah@sheffield.ac.uk abstract frequently, only the mesiodistal dimensions of mandibular posterior teeth have been investigated in relation to lower incisor crowding. the aim of the present study was to investigate any relationship between lower incisor crowding and mesiodistal widths, buccolingual dimensions, occlusal area and occlusal perimeter of mandibular posterior teeth. mandibular dental casts of 50 caucasians (25 males and 25 females) were used. mesiodistal widths, buccolingual dimensions, occlusal area and occlusal perimeter were measured using image analysis techniques. lower incisor crowding was determined using (1) little’s irregularity index and (2) anterior-tooth size arch length discrepancy. using pearson correlation, the occlusal area, perimeter, mesiodistal widths and buccolingual dimensions of the lower first molar were significantly, positively correlated with little’s irregularity index. the significant correlation between occlusal area and crowding did not appear to be secondary to larger mesiodistal widths. dental anthropology 2005;18(2):37-42. (kodak, nikon dcs 410). adobe photoshop (version 5.0, adobe systems ltd., europe) was used to acquire images of the teeth. from all models an occlusal image of each posterior tooth was captured, starting from the lower left first permanent molar to the lower right first permanent molar. for all images the position of the tooth was such that the lens of the camera was focused at right angles to the long axis of the clinical crown. the following measurements were carried out using image pro plus (version 4.0, media cybernetics, usa): 1. area and perimeter: the maximal contour of the occlusal surface of the posterior teeth (from first molar to canine) was traced (fig. 1) giving rise to area (a) and perimeter (p) measurements. 2. mesiodistal width (md): this was measured between the anatomical mesial and distal contacts (fig. 1). 3. buccolingual diameter (bl): the buccolingual diameter was measured as perpendicular to and at the midpoint of the mesiodistal diameter (fig. 1). 4. lower incisor crowding: little’s irregularity index (ii5; little, 1975) and anterior tooth size-arch length discrepancy (atsald) were used to quantify lower incisor crowding. the ii5 is the sum of five contact 38 displacements between the lower anterior teeth. it was measured manually using digital calipers (mitutoyo, japan). the atsald was measured as the difference between the sum of the individual mesiodistal widths of the four lower incisors and the dental arch length, using the image analysis method. the latter was measured on both sides of the arch from the mesial contact point of canine to the contact between the mesial contact points of central incisors. if there was no contact between the central incisors, it was measured between the mesial contact of the canine and the mesial contact point of the central incisor, which was thought to be in normal position. repeatability all teeth were re-imaged and re-measured on a separate occasion after an interval of one week, to assess the reliability of the method. the error of ii5 was calculated by re-measuring the index manually, on ten models on two separate occasions, one week apart. to examine the reliability of atsald, twenty models were re-imaged and remeasured after a one-week interval. systematic error was calculated using paired ttests, and random error was estimated with intra-class correlation coefficients. descriptive statistics and the pearson and spearman correlation coefficients were used to assess the correlation between lower incisor crowding and posterior tooth parameters. results measurement reliability from table 1 it can be seen that the range of error variance for different tooth types for md dimensions of posterior teeth was between 3% and 6%, and for bl tooth dimensions of posterior teeth between 3% and 10%. for area and perimeter measurements error variance ranged from 1 to 3% among the different tooth types. the mean differences between the first and second measurements after re-imaging the teeth were not statistically significant. tooth dimensions and crowding indices the mean and range of md, bl, a and p for canines, premolars and first molars of males are given in table 2 and for females in table 3. in the male group some first molar and second premolar variables showed significant correlations with the crowding indices (table 4). for the occlusal surface of first molars md, bl, a and p were significantly correlated at the 5% level with ii5 (table 4). first molar md dimension showed significant correlation with atsald (p = 0.04), and a and p approached significance (0.10 > p > 0.05). however, the correlation coefficients between these variables and the crowding indices ranged from 0.39 to 0.48, indicating that although an association may exist, it is not high. from table 4 it can be seen that for second premolars md and a were significantly correlated with ii5, with p approaching significance (0.10 > p > 0.05). only md approached a significant association (p = 0.06) with atsald, and the remaining three variables of the second premolar showed no evidence of association with atsald. first premolar and canine variables showed no significant correlation. in contrast, in the female group no evidence was found of an association with either ii5 or atsald. the pearson correlation coefficients (r) ranged from zero to fig. 1. an image of a lower right second premolar with mesiodistal (md), buccolingual (bl), area (a) and perimeter (p) dimensions. the steel rule allows linear calibration of each image. tooth type md bl area perimeter first molar 0.96 (4%) 0.90 (10%) 0.98 (2%) 0.97 (3%) second premolar 0.94 (6%) 0.97 (3%) 0.98 (2%) 0.97 (3%) first premolar 0.95 (5%) 0.95 (5%) 0.98 (2%) 0.98 (2%) canine 0.97 (3%) 0.97 (3%) 0.99 (1%) 0.99 (1%) table 1. intraclass correlation coefficients for re-imaging error of posterior teeth1 a.a. shah et al. 1figures in parenthesis indicate proportion of variance in measurements due to method error 39posterior tooth morphology and crowding 0.37 (table 5). spearman’s correlation coefficients were calculated for all the significant results to check that these were not due to outliers (table 6). the correlation between ii5 and first molar variables remained significant. however, the correlation between md of first molar and atsald, and md and a of second premolar and ii5 lost significance. this showed that the latter significant result was probably due to the presence of an outlier in the data. discussion in the present study, the error variance for posterior tooth variables did not exceed 10% for different tooth types. crown area represented the overall size of the tooth and takes into account both md and bl dimensions. the area of the posterior teeth showed the least error variation in relation to the total variation in the materials studied (1 to 2%). this can be interpreted as suggesting that crown area would be a better single indicator of biological variation than either md or bl alone, where the error variation was 3 to 10% of the total variation. however, combination of the parameters measured is important in considering the shape of teeth, as two teeth with different shapes may have similar area measurements. lower arch crowding is important not only from a clinical point of view, but it also has implications in understanding the controlling factors of tooth size. begg (1954) reported that there was less crowding in the aborigines and he attributed this to greater interproximal attrition, due to ingestion of coarse food in that population. lower incisor crowding has been quantified in different ways, and little’s irregularity index (1975) and atsald are the two methods commonly used in orthodontic literature. even the atsald has been measured in many ways by different investigators. harris (1987) has shown that ii5 and atsald may not measure the same thing and the present study lends support to that suggestion. the results show that area of posterior teeth is an important variable when investigating lower incisor crowding. previous studies have reported a positive correlation between lower incisor crowding and md dimension of posterior teeth, and this association was interpreted as larger teeth occupying more space in the dental arch, which may result in crowding. in this study, however, we have shown that, in males in addition to md and bl dimensions, posterior occlusal area may be associated with lower incisor crowding, and the strengths of the association of these variables with crowding are not substantially different from each other (table 4). in the female group, there was no association of posterior tooth area with lower incisor crowding. it cannot be explained readily whether such an association did not exist in the first place or whether any such association was undetected. the work opens a new dimension for future studies, as the association of md and lower incisor crowding may be secondary to the association of larger posterior tooth area. this is partially supported by previous work (shah, 2000) where 44 variables were measured on lower study models. the number of variables was subsequently reduced to 5 by using principal component analysis. when regression analysis was performed, area and bl width of posterior teeth entered before md dimension in the regression equation. it was further shown that when area for posterior teeth was not included in the regression analysis, the bl dimension preceded the md dimension in significance. while the positive association of the md of molars table 2. measurements (in mm or mm2) for first molar, premolars and canine in the male group first molar second premolar first premolar canine mean range mean range mean range mean range md 10.88 9.8-12.13 7.19 6.27-8.14 7.11 6.21-8.01 6.91 5.70�7.897.11 6.21-8.01 6.91 5.70�7.896.21-8.01 6.91 5.70�7.896.91 5.70�7.89 5.70�7.89 bl 10.49 9.35-11.86 8.53 7.21-9.62 7.96 6.66�9.29 7.90 5.82�9.57 7.96 6.66�9.29 7.90 5.82�9.57 6.66�9.29 7.90 5.82�9.57 7.90 5.82�9.577.90 5.82�9.57 a 100.64 84.8-124.9 50.04 37.62-67.21 44.17 32.9�54.73 41.6 33.45�56.4 44.17 32.9�54.73 41.6 33.45�56.4 32.9�54.73 41.6 33.45�56.4 p 35.58 23.7-40.18 25.37 21.11-29.44 23.79 20.45�26.59 23.98 21.19�35.5 23.79 20.45�26.59 23.98 21.19�35.5 20.45�26.59 23.98 21.19�35.5 first molar second premolar first premolar canine mean range mean range mean range mean range md 10.41 9.02-11.49 6.91 6.20-7.74 6.86 6.11-7.79 6.45 5.56-7.48 bl 10.22 9.00-11.19 8.32 7.14-9.59 7.60 6.67-8.3/9 7.38 6.30-8.21 a 94.27 77.87-105.00 46.48 36.84-56.87 40.51 31.77-47.64 36.49 25.81-46.01 p 34.87 31.79-36.90 24.42 21.74-27.10 22.78 20.16-24.71 21.80 18.40-24.41 table 3. measurements (in mm or mm2) for first molar, premolars and canine in the female group 40 with lower incisor crowding may be readily understood, the association of occlusal area of molars merits further consideration. the literature indicates that, with age, mandibular intermolar and interpremolar widths either increase or remain unchanged (harris, 1997; bishara et al., 1994, 1997). if the buccal teeth are drifting away from the midline, then the supporting bone ought to remodel to accommodate them. data show that this does occur and the changes are in the predicted direction (enlow and harris, 1964; enlow et al., 1976; israel, 1979). the upper molars are slanted buccally and the increase in intermolar and interpremolar widths may be due to displacement of molars buccally by the force of occlusion (harris, 1997). however, haas (1980) found that by expanding the upper arch, lower intermolar and interpremolar widths also increased and it was suggested that this might be as a consequence of the altered forces of occlusion and muscle balance, with buccal tension diminishing and lingual pressure increasing. in postretention studies, variable ii5 (r value) p value atsald (r value) p value first molar md 0.48 0.02* 0.40 0.04* bl 0.44 0.03* 0.29 0.15 a 0.46 0.02* 0.37 0.07 p 0.39 0.05* 0.37 0.09 second premolar md 0.42 0.04* 0.38 0.06 bl 0.31 0.13 0.20 0.16 a 0.39 0.05* 0.30 0.15 p 0.38 0.07 0.27 0.19 first premolar md 0.26 0.21 0.33 0.10 bl 0.10 0.64 0.04 0.83 a 0.16 0.44 0.17 0.42 p 0.20 0.34 0.22 0.29 canine md 0.12 0.57 0.17 0.41 bl 0.05 0.82 0.05 0.79 a 0.15 0.44 0.12 0.57 p 0.01 0.98 0.10 0.64 table 4. pearson correlation coefficients (r) between lower incisor crowding and lower first molar, premolars, and canine in males * p < 0.05 ii5 atsald variable (r value) p value (r value) p value first molar md 0.02 0.92 0.12 0.56 bl 0.02 0.93 0.21 0.32 a 0.05 0.81 0.11 0.60 p 0.11 0.58 0.05 0.80 second premolar md 0.12 0.4 0.37 0.07 bl 0.01 0.95 0.23 0.28 a 0.00 0.98 0.26 0.21 p 0.00 0.99 0.24 0.24 first premolar md 0.02 0.93 0.21 0.31 bl 0.01 0.95 0.19 0.37 a 0.12 0.35 0.19 0.36 p 0.12 0.56 0.17 0.40 canine md 0.02 0.92 0.17 0.41 bl 0.19 0.36 0.21 0.31 a 0.04 0.83 0.23 0.26 p 0.05 0.80 0.24 0.25 table 5. pearson correlation coefficients (r) between incisor crowding and lower first molar, second premolars, and canine in females a.a. shah et al. 41 lower incisor alignment appears to be more stable in cases where upper arch expansion has been carried out (moussa et al., 1995; elms et al., 1996; azizi et al., 1999; shah 2003). at the same time, arch length and intercanine width decrease. we also know that posterior teeth move forward as a result of mesial drift with age (begg, 1954; beek, 1979) and, except for the increase in intermolar and interpremolar widths, all the remaining phenomenons will obviously have an adverse effect on lower incisor alignment. it may be that the simultaneous increase in intermolar and interpremolar width results in less incisor crowding. wolpoff (1971) concluded that as the roots of the posterior teeth are inclined forward in the jaws, so chewing forces create a mesial force vector. therefore, the greater the chewing forces, which are determined by the nature of the diet, the higher the mesial force vector. however, as pressure is force per unit area, theoretically one would expect less pressure application to posterior teeth having a larger occlusal area, assuming there will be larger contact areas in the latter. this would cast doubt on the speculation that chewing forces might be associated with lower incisor crowding and/or mesial migration of the posterior teeth. this is supported in the present study where a larger occlusal area was positively associated with lower incisor crowding. this is further supported by hidaka et al. (1999) who found that when the bite force increased with clenching intensity, occlusal contact area on the whole arch increased but the mean bite pressure (bite force per contact area) remained unchanged. therefore, the effect of a larger occlusal area may be operating by different mechanisms. two possible mechanisms can be offered where larger molar occusal area may cause more lower incisor crowding: 1. potential for buccal expansion may be reduced with larger posterior tooth area. firstly, the morphology of the crown or root of posterior teeth associated with larger posterior tooth area may not allow the buccal movement of molars and the compensatory mechanism of an increase in intermolar and interpremolar widths does not operate. secondly, there may be a difference in the path of eruption induced by a particular morphology and the posterior teeth might have less potential for buccal expansion. thirdly, there may be an alteration in the direction of occlusal forces associated with larger posterior tooth area. 2. mesial migration of the posterior teeth may be accelerated. mesial migration may increase due to a larger posterior tooth area. this affect would not occur due to an increased bite force, but may be due to alteration in the directions of occlusal forces or due to alteration in the path of eruption of the posterior teeth. for the posterior tooth variables in the female group, none was significantly correlated with the crowding indices. why the posterior occlusal area in the female group showed no significant correlation with lower incisor crowding cannot be established. the ages of male and female subjects were comparable, but the crowding scores in the male group were higher than in the female group (shah et al., 2003). the difference in crowding between the two groups may have resulted in different relationships. in the literature, contact area tightness has been investigated in relation to various parameters, such as head posture, tooth type, location in the jaw and time of day (southard et al., 1990; dorfer et al., 2000). however, there is no literature to investigate the relationship between posterior tooth area and the contact area tightness between adjacent teeth. it would be worthwhile to investigate any association between posterior tooth occlusal area and the contact area tightness pressure, when a given amount of bite force is applied on the molar teeth and a pilot study is being currently formulated. conclusions 1. image analysis is a reliable technique for measuring the area, perimeter, md and bl dimensions of posterior teeth. 2. lower incisor crowding was associated in this study with mandibular posterior tooth area, md and bl dimensions in males. table 6. spearman correlation coefficients (r) between incisor crowding and lower first molar and second premolar variables in males. variable ii5 (r) p value atsald (r) p value first molar md 0.50 0.01* 0.23 0.20 bl 0.45 0.02* 0.24 0.25 a 0.48 0.01* 0.30 0.14 p 0.38 0.06 0.31 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width, arch length, and tooth size in young adult males. angle orthod 34:124-129. moussa r, o’reilly mt, close jm. 1995. long-term stability of rapid palatal expander treatment and edgewide mechanotherapy. am j orthod dentofacial orthop 108:478-488. norderval k, wisth pj, boe oe. 1975. mandibular anterior crowding in relation to tooth size and craniofacial morphology. scand j dent res 83:263-273. peck s, peck h. 1972a. crown dimensions and mandibular incisor alignment. angle orthod 42:148153. peck h, peck s. 1972b. an index for assessing tooth shape deviations as applied to the mandibular incisors. am j orthod 61:384-401. radnzic d. 1988. dental crowding and its relationship to mesiodistal crown diameters and arch dimensions. am j orthod dentofacial orthop 94:50-56. shah aa. 2000. an investigation of the relationship between mandibular tooth morphology and lower incisor crowding using a new image analysis system. unpublished ph.d. dissertation, university of sheffield, england. shah aa. 2003. postretention changes in mandibular crowding: a review of the literature. am j orthod dentofacial orthop 124:298-308. shah aa, elcock c, brook ah. 2003. relationship between incisor crown shape and crowding. am j orthod dentofacial orthop 123:562-567. southard te, southard ka, tolley ea. 1990. variation of aproximal tooth contact tightness with postural change. j dent res 69:1776-1779. wolpoff mh. 1971. interstitial wear. am j phys anthropol 34:205-228. a.a. shah et al. cucina et al. 2002.2 44 45 oral pathologies are tightly related to subsistence patterns and they are utilized in anthropological studies as a means to assess diet and food preparation techniques (powell, 1985; lukacs, 1989; larsen et al., 1991; larsen, 1997; hillson, 2000). in ancient maya society, diet has been investigated in several ways and under various perspectives, related to the “maya collapse” and to the shift from the preclassic to the classic and postclassic periods (whittington and reed, 1997a; white, 1999). studies of oral pathologies and of stable isotopes have indicated dietary heterogeneity between sites (sanders and price, 1968; gerry and krueger, 1997) although a common pattern shared by the whole maya society was its strong reliance on maize (landa, 1566; lentz, 1991; gerry and krueger, 1997; white, 1997). sex differences have been taken into account in the assessment of diet, though often without analyzing and interpreting the data within a more complex socioeconomic and cultural framework. at copán for example, only the commoner portion of the society was investigated. females showed higher frequency of caries than males, and this was explained as the result of a higher intake of carbohydrates and a less diversified diet in the formers (whittington and reed, 1997b; whittington, 1999). the present study reports preliminary findings on differences in the occurrence of oral pathologies by sex and compounds in the classic maya site of xcambó (ad 300-900) from northern yucatán peninsula (méxico) (fig. 1). the site was a center for salt production and trade (sierra sosa, 1999), strategically located next to the coast on a natural small mound surrounded by marshlands, not far from the town of dzibilchaltún. the site’s economical and geographical characteristics and the provenience of the remains from different areas (i.e., compounds) within the site made the sample interesting to with respect to the analysis of social and sexual aspects of the occurrence of oral pathologies in males and females within and between compounds. this paper aims at answering research questions in terms of social structure and the population’s internal composition. this study is part of a broader project on population relationships and lifestyles of this population as a unit and as part of a larger social and economic regional network. the network orbited around dzibilchaltún but expanded as far as guatemala to the south and veracruz to the west because of its role in salt production and trade (sierra sosa and martínez lizarraga, 2001). materials and methods the human skeletal remains currently available for analysis consists of a sample of 200 individuals, of which only 150 possess permanent dentition and/or dental bony support. most individuals (n = 129) belong to the late classic period (ad 600-900), the others are from to the early classic period (ad 300-600). the remains were grouped sex differences in oral pathologies at the late classic maya site of xcambó, yucatán1 andrea cucina1*, vera tiesler blos1and thelma sierra sosa2 1facultad de ciencias antropológicas, universidad autonoma de yucatán, mérida. yucatán 2centro inah yucatán, mérida, centro inah yucatán, mérida, yucatán abstract the present study compares the frequency of oral pathologies—namely caries, antemortem tooth loss and periapical defects—between sexes in the maya site of xcambó, yucatán, during the late classic period (ad 600-900). there are marked differences in the occurrence of oral pathological conditions between the sexes in two of three major areas of the sites, despite evidence of archaeological and funerary homogeneity within the site. in these two compounds, females are significantly more affected by oral pathologies than males. in contrast, the third area of the site shows slightly higher frequencies in males, but with no significant sex difference. the results *correspondence to: andrea cucina, facultad de ciencias antropológicas, universidad autonoma de yucatán, mérida, yucatán, mexioco. e-mail: acucina@yahoo.com have been interpreted according to the site’s location, size and economic role within a larger trade network in the yucatán peninsula. the higher frequency of oral pathologies in females is interpreted as the result of sex differences in dietary and behavioral patterns. females likely had more maize in their diet and, because of their role in food preparation, may have ingested food more frequently during the day. at the same time, the lack of difference between sexes in the third area of the site contradicts the archaeological evidence of intrasite homogeneity, and it raises questions on the cultural complexity of this population. 1a version of this paper was presented at the xvi simposio de investigaciones arqueologicas en guatemala. guatemala city, july 15-19, 2002. 46 47a. cucina et al. and analyzed according to sex and burial placement. three major compounds where distinguished: the central compound (asentamiento central; ac), the central-administrative compound (asentamiento central administrativo; aca) and the patio groups to its east (asentamiento periférico este; ape) (fig. 1). in all, the sample totals 2676 permanent teeth. since this investigation focuses on oral pathologies between sexes, only the adult, sexed individuals and their teeth have been used, and the numbers are listed in table 1. for obvious reasons, these values are lower than the total ones. all permanent teeth and tooth sockets of the adult sexed individuals were evaluated for oral pathologies according to the methods of metress and conway (1975) and marafon (1976), and following the discussion in buikstra and ubelaker (1994). caries were scored on each permanent tooth and registered as present when the cavity had reached the dentine and could be clearly detected both visually and with a dental probe. the number of teeth affected and the total available for analysis are listed in table 2. antemortem tooth loss (amtl) was calculated only on the basis of remodeled tooth sockets in comparison with non-remodeled ones to reduce the bias introduced by poor bone preservation and the associated underestimation of teeth lost during life. their values and frequencies are reported in table 3. periapical defects appear as round enlargements due to inflammatory processes and bone remodeling. the defects are characterized by smooth homogeneous surfaces on the apical part of the alveolar socket (marafon, 1976; lukacs, 1989). these defects were registered as “present” when they could be detected at the apical extremity either because the inflammation had destroyed the external bony tissue or because it was possible to remove the tooth from the jaw and investigate the socket. all the other cases were recorded as “absent”. lukacs (1989) reported that this procedure may underestimate the actual frequency of defects, but in the case of xcambó the few teeth that could not be removed were not associated with caries and were not affected by heavy occlusal wear, which makes them likely to represent “healthy” sockets. the final values and frequencies for this type of pathological condition are listed in table 4. the site the occupational sequence at xcambó starts in the preclassic period (ad 100-250). during the early (ad 300-600) and late (ad 600-900) classic, xcambó became a thriving center of salt production and trade (sierra sosa, 1999). the site, which is 700 meters long and 150 wide, was constructed on top of an artificially elevated, single large platform emerging from the swampy marshland. canals and trails connected xcambó with both the coastal strip and the inland areas. the small size of the site and the characteristics of the natural table 1. number of individuals analyzed for caries, amtl and periapical defects according to sex periapical caries amtl defects males 62 63 62 females 37 39 34 fig. 1. geographical location of the site and close up of the site and compounds. 46 47 mound limited the expansion of its monumental religious and administrative center and the associated domestic areas (sierra sosa, 1999; sierra sosa and martínez lizarraga, 2001). extensive and intensive archaeological surveys at the site were performed between 1996 and 2000 by the national institute of anthropology and history (inah). in the course of the excavations more than 600 burials were retrieved from both the residential compounds and the central structures. findings indicate a relative abundance and homogeneity in the distribution of funerary objects associated with the skeletons compared to other sites in the area. this, along with architectural homogeneity, points towards limited internal social differentiation at xcambó (sierra sosa and martínez lizarraga, 2001). results tables 2 through 4 list the sample sizes and the frequencies of caries, amtl and periapical defects divided by sex and compounds of xcambó. the same values are graphically represented in figures 2 through 4. some from the three compounds belonged to the early classic period, but the majority were from the late classic. individuals were not differentiated according to chronological horizon because of the small number of individuals from the early classic period, and because any chi-square analysis run between the subsamples did not indicate statistically significant differences between the periods. the only case where a difference was significant significantly was the frequency of amtl in the males from the ac compound (p values from chi-square test with one degree of freedom were 0.011 anterior dentition, 0.011 posterior dentition, and 0.000 total). in this case, as in table 3 and figure 3, the two periods have been considered separately. the age distribution within each subgroup was similar and differences were not statistically significant among compounds. for this reason, we could rule out age at death as a factor influencing the rate of oral pathologies in the between-groups analysis. sex differences were evident for all the pathological conditions. females showed much higher frequencies of oral pathologies than males, with the one exception of the ape compound. in this case, males surpass females. chi-square p values for all the possible pairwise comparisons are listed in table 5. differences between sexes were significant for the three pathological conditions in aca and ac but not significant in ape. within-sex comparison shows that the major changes in frequency are encountered between ape and the two other groups. females at ape are constantly and significantly less affected than their counterparts in the two other compounds. in turn, no difference table 2. number of teeth affected by caries, total number of scorable teeth available and percent affected anterior1 posterior2 anterior +posterior aca males 3 87 3.4 19 158 12.0 22 245 9.0 females 13 42 31.0 25 62 40.3 38 104 36.5 ac males 14 276 5.1 88 457 19.3 102 733 13.9 females 31 99 24.0 58 177 32.8 89 276 32.2 ape males 6 47 12.8 20 101 19.8 26 148 17.6 females 2 40 5.0 11 76 14.5 13 116 11.2 total 69 591 11.7 221 1,031 21.4 290 1,622 17.9 1anterior teeth are incisors and canines 2posterior teeth are premolars and molars fig. 2. frequency of caries according to sex and compounds of the site oral pathology at xcambó 48 49a. cucina et al. was encountered in males from the later period among compounds. caries differences are significant only between aca and ape. the most noteworthy, significant differences occur when the ac early males are compared for amtl with the other later males. in this case differences are always significant both in comparison with the other compounds and within ac. discussion data on the distribution of oral pathologies by sex at xcambó reveal some interesting tendencies. the first is that females in general were much more often affected by oral pathologies than males, and the second is that this pattern is common throughout the whole site with the exception of one particular area, the asentamiento periferico este (ape), which shows the opposite tendency. several researchers suggest that females are often affected by a higher frequency for oral pathologies than males (larsen et al., 1991; larsen, 1997; whittington and reed, 1997b; storey, 1999; whittington, 1999). the interpretations encompass a large range of hypothesized causes: differences in diet between males and females, increased susceptibility in the latter, ad a longer time for pathologies to occur in females (given their earlier age of dental eruption and longer life span). a specific cause alone is not sufficient, and every situation is unique in terms of reasons underlying the frequency of oral pathologies (powell, 1985). larsen et al. (1991) noted that major differences between periods in the archaeological samples from the georgia coast area occurred after the shift in diet from hunting and gathering to agriculture and were not related to age at death. in the sample from xcambó, age at death does not differ among compounds or between males and females, which rules out the possibility that higher frequencies might be related to longer exposure to cariogenic agents. moreover, the archaeological evidence indicates that the population of xcambó was socially homogeneous (sierra sosa and martinez lizarraga, 2001). differences are mainly between sexes and not between compounds. this homogeneity excludes marked social stratification as one possible cause for different frequencies of oral pathologies, in contrast with what suggested for the maya site of calakmul (cucina and tiesler, 2002). thus, the causes of the differences encountered between sexes should be sought in the kind of diet and/or behavioral and cultural patterns. indeed, we think that the sex differences are multifactorial in nature and are likely to be related to the characteristics of the site. the site of xcambó was small in size but an economically important center of salt production and trade (sierra sosa, 1999). the site’s limited boundaries forced those committed to salt production to work outside the residential area. in most societies, males are those who do the manual labor and females are responsible for the household and food preparation. a model where men and women experience different types of nutrition, where males receive more protein in their diet because of the heavyduty labor, explains their lower rate of cavities (lee and devore, 1968; larsen et al., 1991). females might have been exposed to oral pathologies because of a diet where carbohydrates prevailed and because of a more frequent ingestion of food during the day. larsen and colleagues (1991) pointed that the higher frequency of oral pathologies in females could be attributed to their engagement in food preparation, resulting in more frequent ingestion of food during the day, in comparison to males who may have eaten the same kind food but at specific hours during the day. the individuals from the ape compounds show a different pattern. cultural differences may be at the base of such discrepancy, in particular with respect to females’ activities, even though the archaeological record does not reveal evidence that would support fig. 3. frequency of antemortem tooth loss by sex and compounds (males have been sorted by period: m(e) early classic, m(l) late classic.) fig. 4. frequency of periapical defects by sex and compounds of the site. 48 49 table 4. number of sockets showing periapical defects, total number of scorable sockets, and the frequency of these defect anterior posterior total present n % present n % present n % aca males 3 93 3.2 22 147 15.0 25 240 10.4 females 10 53 18.9 15 51 29.4 25 104 24.0 ac males 22 350 6.3 77 465 16.6 99 815 12.1 females 26 173 15.0 37 205 18.0 63 378 16.7 ape males 3 77 3.9 18 109 16.5 21 186 11.3 females 2 51 3.9 8 77 10.4 10 128 7.8 total 66 797 8.3 177 1,054 16.8 243 1,851 13.1 the difference between ape females from the others. nonetheless, the small size of the ape sample does not allow us to draw clear conclusions, and the data may result from sampling bias. a more thorough assessment will be possible when all the remains are studied. similarly, a chronological interpretation of the differences encountered in the frequency of amtl in the males from the ac group is not conclusive at this time because of the small size of the early classic sample. conclusions in conclusion, this preliminary analysis of oral pathologies from the site of xcambó reveals interesting evidence that may link cultural and dietary factors to the geographical location and physical structure of the site as a unit, and as part of a wider, more complex economic and trade network. the different results obtained from the various compounds seem to contradict the homogeneity encountered at the archaeological level. although this can be due to the small sample size of ape, it will stimulate further analyses addressing the biological and cultural complexity of the dynamic maya population in yucatán. literature cited buikstra je, ubelaker dh. 1994. standards for data collection from human skeletal remains. fayetteville: arkansas archaeological survey research series 44. cucina a, tiesler v. 2002. dental caries and antemortem tooth loss in the northern peten area, mexico: a biocultural perspective on social status differences among the classic maya. am j phys anthropol 119: (in publication). gerr jp, krueger hw. 1997. regional diversity in classic maya diet. in whittington sl, reed dm, editors. the bones of the maya. washington: smithsonian institution press. p 196-207. hillson s. 2000. dental pathology. in: katzenberg ma, saunders sr, editors. biological anthropology of the human skeleton. new york: wiley-liss. p 249-286. table 3. number of sockets indicating amtl, number of total sockets and frequency of amtl anterior posterior total amtl n % amtl n % amtl n % aca males 20 116 17.2 25 184 13.6 45 300 15.0 females 10 64 15.6 25 86 29.1 35 150 23.3 ac males e 11 51 21.6 25 77 32.5 36 128 28.1 males l 30 342 8.8 100 523 19.1 130 865 15.0 females 35 201 17.4 120 319 37.6 155 520 29.8 ape males 6 85 7.1 17 124 13.7 23 209 11.0 females 4 55 7.3 22 101 21.8 26 156 16.7 total 116 914 12.7 334 1414 23.6 450 2328 19.3 oral pathology at xcambó 50 51a. cucina et al. table 5. p values from the chi-square analyses between sexes and between compounds1 caries amtl periapical defects anterior posterior total anterior posterior total anterior posterior total analysis within compounds2 aca m vs f ** ** ** n.s. ** * ** * ** ac m(e) vs m(l) * * ** m(e) vs f n.s. n.s. n.s. m(l) vs f ** ** ** m vs f ** ** ** ** n.s. * ape m vs f n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. analysis within sex2 males aca vs ac(e) n.s. ** ** aca vs ac(l) n.s. n.s. n.s. ape vs ac(e) * * ** ape vs ac(l) n.s. n.s. n.s. aca vs ape * * * * n.s. n.s. n.s. n.s. n.s. aca vs ac n.s. n.s. n.s. n.s. n.s. n.s. ape vs ac n.s. n.s. n.s. n.s. n.s. n.s. females aca vs ac n.s. n.s. n.s. n.s. n.s. n.s. aca vs ape ** ** ** ** ** ** ape vs ac ** ** ** ** ** ** 1 the ac compound is the only one where males were kept separate according to chronology: m(e) stands for males early period, m(l) for males late period. females were all pooled together. 2 n.s. = p > 0.05; * = 0.05 ≥ p > 0.01; ** = p ≤ 0.01 (1 df). landa d de. 1978 (1566). relación de las cosas de yucatán. porrúa: mexico. larsen cs. 1997. bioarchaeology. cambridge: cambridge university press. larsen cs, shavit r, griffin mc. 1991. dental caries evidence for dietary change. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york, wiley liss. p 179-202. lee rb, devore i. 1968. man the hunter. chicago: aldine. lents dl. 1991. maya diets of the rich and poor: paleoethnobotanical evidence from copán. lat am antiq 2:269-287. lukacs jr. 1989. dental paleopathology: methods for reconstructing dietary patterns. in: iscan my, kennedy kar, editors. reconstructing life from the skeleton. new york: wiley liss. p 261-286. marafon g. 1976. odontoiatria. roma: almes. metress jf, conway t. 1975. standardized system for recording dental caries in prehistoric skeletons. j dent res, 54: 908. powell ml. 1985. the analysis of dental wear and caries for dietary reconstruction. in: gilbert ri, mielke lj, editors. the analysis of prehistoric diets. new york: academic press. p 307-338. sanders wt, price bj. 1968. mesoamerica: the evolution of a civilization. new york: random house. sierra sosa tn. 1999. xcambó. codiciado puerto del clásico maya. inaj semilla de maíz. conaculta, inah. 10. sierra sosa tn, martínez lizarraga a. 2001. los entierros de xcambó y sus implicaciones socials. inaj semilla de maiz. conaculta, inah 12:6-12. storey r. 1999. late classic nutrition and skeletal indicators at copán, honduras. in: white cd, editor. reconstructing ancient maya diet. salt lake city: the university of utah press. p 169-179. whittington sl. 1999. caries and ante mortem tooth loss at copán. implications for commoner diet. in: white cd, editor. reconstructing ancient maya diet. salt lake city: the university of utah press. p 151167. 50 51 white cd. 1997. ancient diet at lamanai and pacbitun: implication for the ecological model of collapse. in: whittington sl, reed dm, editors. bones of the maya: studies of ancient skeletons. washington: smithsonian institution press. p 171-180. white cd, ed. 1999. reconstructing ancient maya diet. salt lake city: the university of utah press. whittington sl, reed dm, editors. 1997a. bones of the maya: studies of ancient skeletons. washington: smithsonian institution press. whittington sl, reed dm. 1997b. commoner diet at copán: insights from stable isotopes and porotic hyperostosis. in: whittington sl, reed dm, editors. bones of the maya: studies of ancient skeletons. washington: smithsonian institution press. p 157170. whittington sl. 1999. caries and antemortem tooth loss at copán: implications for commoner diet. in: white cd, editor. reconstructing ancient maya diet. salt lake city: the university of utah press. p 151-167. oral pathology at xcambó decoding your subscription want to know when your subscription to dental anthropology expires? membership in the association and, thus, your subscription to dental anthropology is on an annual basis coinciding with the calendar year. have a look at the mailing label on the evelope that this issue arrived in, and you will see the year for which your dues have been paid. the year is located in parentheses to the right of your name. so, if the mailing label says “(2003)” you are paid to the end of this calendar year. in order to extend your membership, fill-out the relevant portions of the enclosed renewal form—remember to include appropriate payment—and mail it to the secretary-treasurer of the association: dr. diane hawkey department of anthropology arizona state university tempe, arizona 85287-2402 usa e-mail: hawkey@asu.edu smith and harris 2008.4 54 most people develop all 32 permanent teeth, but the congenital absence of one or more of these teeth is not uncommon (pindborg, 1970). indeed, no tooth type is immune to failure-to-form, though some tooth types, notably the maxillary lateral incisor and second premolars are comparatively likely to experience congenital absence (egermark-eriksson and lind, 1971; mattheeuws et al., 2004). on the other hand, canines are renowned for their developmental stability; canines are the teeth least likely to be congenitally absent (polder et al., 2004). the population incidence of missing canines is hard to determine accurately because of variations among studies in selection criteria (e.g., whether syndromes are included), sampling fluctuations, and whether absence is verified radiographically (so failures of eruption can be distinguished from failure of formation). the purpose of this report is to describe two contemporary clinical cases that are unusual in that both permanent canines are missing from one arch. there appears to be little effect of this rare form of hypodontia on the other teeth in one case, while the other case has additional missing teeth. case discovery one case (kp) was identified during a systematic review of orthodontic patients (harris and clark, 2008). these were “phenotypically normal” cases, where those with syndromes or other conditions known to enhance the risk of hypodontia had been culled. exempted conditions included clefts of the lip and palate, hypohidrotic ectodermal dysplasia (itin and fistarol, 2004), and cases probably due to pax9 or msx1 (or similar major genes) that cause oligodontia congenital absence of permanent canines: report of two cases ann s. smith* and edward f. harris department of pediatric dentistry, university of tennessee, memphis correspondence to: ann s. smith, department of pediatric dentistry, university of tennessee, memphis, tennessee u.s.a. 38163 e-mail: asmit138@utmem.edu abstract congenital absence of permanent canines is a rare event, especially when syndromic cases are excluded. our data suggest a population frequency of roughly 1 per 1,000 people. this report describes two contemporary cases with radiographically-confirmed bilateral absence of the maxillary canines. one is a case of simple hypodontia, where only the upper canines failed to develop (though the lateral incisors are undersize). the other case exhibits the additional absence of maxillary lateral incisors and second premolars. these cases add weight to prior findings that (a) the canine is the tooth type least likely not to form, (b) upper canines are more likely to be missing than mandibular canines, and (c) the frequency is higher in females than males. dental anthropology 2008;21(2):54-59. (mostowska et al., 2003; vieira, 2003; larmour et al., 2005). the second case (ls) was encountered during routine treatment in a pediatric dental clinic and was referred to the authors for consultation. both cases were free of any identifiable developmental problem aside from the isolated hypodontia, though they were not tested genetically. case kp this is a 15-7 year-old american black female (fig. 1) who presented to the department of orthodontics with the major complaint that she disliked the space (ca. 5 mm) between her maxillary central incisors. she herself was unaware that her canines were congenitally absent. indeed, given the high incidence of impacted maxillary canines (e.g., bishara, 1998; richardson and russell, 2000), their absence on initial visual inspection was not surprising; the orthodontist assumed at first that they were merely impacted. on radiographic examination, their absence was confirmed, though all 30 of the other permanent teeth were present. all four third molars appear to be eumorphic on x-ray. absence of the canines had led to lateral migration of the incisors, with interdental spacing, notably development of the midline diastema (fig. 1). this recalls moorrees’ (1959) finding (and those of baume (1950) and others) that the mesially-canted eruption paths of the canines promote consolidation of the 55 fig. 1. panoramic radiograph of case kp. all of the permanent teeth, including the 4 third molars, are mineralizing. congenital absence is limited to the left and right maxillary canines. fig. 2. intraoral photographs of case kp. the missing maxillary canines are thought to contribute to the tapered arch form and the interdental spacing, particularly the maxillary midline diastema. the maxillary lateral incisors are undersize, notably in the subject’s right quadrant. premolar displacements (upper left and lower left quadrants) likely are due to early loss of primary teeth, though there is no solid dental history for this case. incisors and, perhaps, lead to incisor crowding at this stage. it seems that, without the canines, incisors in the anterior segment remain spaced. overjet and overbite were both near-zero; indeed, there are small wear facets on some of the incisors where they occluded end-on. the maxillary left lateral incisor was in crossbite. the other obvious occlusal issue was that the mandibular right canine was displaced to the lingual while the adjacent first premolar was displaced to the buccal. one conjecture is that this premolar’s eruption was diverted out of the arch form because of early loss of arch space that should have been retained by the deciduous canine and first molar in that quadrant (cf. stefan, 2006). absence of the canines and asymmetric loss of primary teeth led to an asymmetric arch form (more obvious in the maxilla), where the buccal teeth on the right side are positioned farther mesially. this translated into a class i buccal segment relationship on the left and an end-on class ii relationship on the right (cf. harris and corruccini, 2008). the maxillary right deciduous canine had exfoliated some time ago, and mesial drift of the premolars and molars in that quadrant closed the space, so the first premolar was abutted against the lateral incisor. the deciduous canine on the left exfoliated quite recently, and a 9 mm space occurred behind the lateral incisor on that side when the pretreatment orthodontic records were taken. obvious orthodontic treatment options were either (1) to open the canine spaces for osseointegrated singletooth implants (e.g., higuchi, 2000) or (2) to close the spaces, substituting (and recontouring) the first premolars to function as the canines. the latter course was chosen here, which required that the mandibular first premolars be extracted as part of treatment to achieve proper interdigitation between the jaws. it is evident on inspection that, while all 30 teeth are present in this case (figs. 1, 2), the maxillary lateral incisors are undersize: the right lateral incisor is small congenital absence of maxillary permanent canines 56 m2 m1 p2 p1 c i2 i1 m2 m1 p2 p1 c i2 i1 -4 -3 -2 -1 0 1 2 3 standard deviations m a x il la m a n d ib le fig. 3. bar chart of the mesiodistal crown dimensions of case kp, expressed as z-scores. aside from the small maxillary lateral incisors, all other tooth types are of at least normal size, suggesting that congenital absence of the canines is an anatomically localized, not a systemic problem, in this girl. the reference sample used here for comparison is the group of african american girls decscribed by richardson and malhotra (1976). mesiodistally (7.0 mm) and the left lateral incisor is pegged with an essentially circular cross section (5.0 mm). the mesiodistal crown dimensions of this case are graphed as z-scores (standard deviation units) in fig. 3. aside from the undersize maxillary lateral incisors just mentioned, none of the other tooth types is noteworthy; in fact, most dimensions are slightly above the average. case ls the second case is a healthy american white female referred for consultation. the panoramic radiograph, taken at age 9-1 years (fig. 4), reveals a mixed dentition with congenital absence of at least six permanent teeth (third molars not yet discernible). specifically, there is bilateral absence of the permanent maxillary lateral incisors, canines, and second premolars. at this chronological age, third molar crypt formation often is evident (e.g., rantanen, 1967), but not in this girl. history also revealed congenital absence of the primary maxillary lateral incisors. this recalls the developmental issue that, when a primary tooth is congenitally absent, most times the successor also will be absent because the permanent tooth bud branches off from its predecessor— so absence of a primary tooth often foretells absence of its permanent replacement tooth (e.g., avery, 1994). evaluation disclosed variability of developmental stages among the molar types. the development of the second maxillary right molar appears questionable (fig. 4). studies suggest that tooth development is delayed in cases of hypodontia (uslenghi et al. 2007). using the demirjian standards for tooth development (demirjian et al., 1973) that we have adapted for the local population, this girl has a dental age of 5.9 years, which is delayed by 35% compared to her chronological age of 9.1 years. mesial drift of the maxillary first premolars into the sites of the canines is evident on the panoramic radiograph (fig. 4). as well, there has been lateral drift of the central incisors that has established a prominent midline diastema. lower anterior crowding also is evident. the malocclusion was treatment planned for serial extractions of the primary teeth and extraction of the mandibular first premolars. age-appropriate maxillary anterior implants are included in the treatment plan to be placed when the bulk of the girl’s facial growth is completed. hypodontia the two cases described here are unusual in that congenital absence of permanent canines is rare, notably so in cases of simple hypodontia (in contrast to cases with oligodontia; schalk-van der weide, 1992). in a systematic review of adolescent cases with hypodontia (harris and clark, 2008), only 1 case of missing permanent canines was found in the sample of 1,600, yielding a frequency of 0.06%. of note, this study excluded craniofacial syndromes and cases with oligodontia. this frequency is the same order of magnitude as reported by dolder (1937) at 0.06% and by bergström (1977) at 0.23%. a recent study by fukuta and coworkers (2004) identified 65 cases of congenitally missing permanent canines in their review of 35,927 dental patients (0.18%), but this included cases of complex hypodontia. large studies such as this suggest that canine hypodontia (a) is more common in females than males, (b) is more common in the maxilla than the mandible, and (c) tends to be associated with hypodontia of other permanent teeth a.s. smith and e.f. harris 57 fig. 4. panoramic radiograph of case ls. both maxillary canines are congenitally absent, as well as the lateral incisor and the second premolar in both maxillary quadrants. the other teeth are of normal size and morphology, though the girl is too young to know whether the third molars will develop. notice, too, that it is uncertain whether the maxillary right second molar is forming; in any event it is appreciably delayed relative to the three other second molars. there is no third molar crypt formation in this girl (9-1 years). the developing maxillary first premolars are rotated (so both the lingual and buccal cusps are readily evident), but this is not particularly unusual. l (particularly maxillary lateral incisors, mandibular central incisors, and premolars). failure of a tooth’s formation can occur at any of several steps during odontogenesis. perhaps the most obvious situation is where the molecular signal from the ectoderm to the underlying mesoderm (dental lamina) fails to occur, so there is no initiation of bud formation, though the specific causes do not seem to be known. formation also might cease when reciprocal signaling from the mesenchyme back to the ectoderm is lacking (e.g., peters et al., 1998). formation also may cease during bud formation and, thus, before the initiation of mineralization (harris, 2002). this has been documented in mice, rats, and rabbits. these animals do not possess lateral incisors (nor canines, nor premolars). however, careful histological study (fitzgerald, 1973; moss-salentijn, 1978) discloses that lateral incisors begin formation, but development ceases in the bud stage, presumably because signaling to promote morphodifferentiation is lacking. causes of tooth suppression (or interrupton of formation) probably differ among species (e.g., peterková et al., 2002). in the mouse, sprouty genes (antagonists of fibrobast growth factor (fgf) signaling) suppress tooth formation in the incisor-to-molar diastema by inhibiting shh (sonic hedgehog) in this region. the mode of action seems to be that shh expression in the diastema inhibits fgf signaling from the mesenchyme (klein et al., 2006). of course, the mechanism in humans—let alone in the cases described here—may be unrelated to this scenario, but the point is that tooth agenesis has its basis in some failure of chemical signaling to promote development. influences from the environment also need to be considered as influencing the risk of hypodontia (where the “environment” interrupts normal biochemical signaling). the conjecture is that greater environmental stress on an individual during tooth initiation increases the risk of hypodontia. “anthropological” cases of “stressed” populations (e.g., bailit et al., 1970) do not provide strong evidence of this because the level of stress is merely conjectured post hoc. we suggest that a more telling situation occurs in children treated for acute lymphocytic leukemia (e.g., kaste et al., 1997). these children are otherwise normal, but have acute onset of leukemia that has to be treated aggressively with chemotherapy and/or cranial irradiation (pui, 1999). hypodontia consequent to irradiation is predictable because the formative cells are killed (kaste and hopkins, 1994). notably, children treated with chemotherapy alone also have substantially greater frequencies of hypodontia (weathersby, 2006). we interpret these cases as dramatic situations in which the environmental stressors (chemotherapy) can halt tooth development. harris and hullings (1990) suggested a similar scenario for children with cleft of the lip and palate. congenital absence of maxillary permanent canines 58 hypodontia is appreciably higher in children with clefts (böhn, 1963; ranta, 1983, 1986), and harris speculated that this is consequent to the cleft, with failure to thrive, recurrent middle ear and upper respiratory infections, the stress of repeated surgeries, and the like. the scenario— greater hypodontia in response to greater environmental stress—is still attractive, but it is considerably more speculative now that there is greater appreciation of a genetic basis for isolated (nonsyndromic) clefts (e.g., peters et al., 1998l; satokata and maas, 1994; vieira, 2003; zucchero et al., 2004). mutant forms of pax9, msx1, and axin2, among other genes, have been documented to promote hypodontia (cobourne, 2007; matalova et al., 2008). these genes, however, have fairly dramatic effects—typically resulting in the congenital absence of multiple teeth. in part, this is because it has been technically easier to identify the familial effects of genes with dramatic effects on the phenotype. one supposes that other genes, with less severe and, thus, more common effects—such as the absence of single teeth (“simple hypodontia”) will be identified with more refined studies in the future. the canine sadly, we offer no explanation for the symmetric congenital absence of permanent canines in the two cases described here. although there is only one canine per quadrant, the canine rarely is absent, and its morphogenetic effects on adjacent teeth in terms of cingular morphology (turner, 1969; scott, 1977) and the extent of sexual dimorphism (garn et al., 1977) are well documented. the literature suggests that there is some familial aggregation of canine absence (e.g., postello, 1984; huggare, 1984)—which might imply a genetic basis for some cases—but such case studies probably are over-reported since they are noteworthy. alternatively, very few studies have explicitly studied hypodontia in sibships (as opposed to samples of biologically unrelated individuals), so an unbiased estimate of recurrence in families is unavailable. overview two cases of congenital absence of permanent maxillary canines are described. in one case, these are the only teeth that failed to form; in the other, maxillary lateral incisors and second premolars also were absent. etiology of this rare condition remains speculative. references cited avery jk, editor. 1994. oral development and histolog, 2nd ed. new york: thieme medical publishers, inc. bailit hl, workman pl, niswander jd, maclean cj. 1970. dental asymmetry as an indicator of genetic and environmental conditions in human populations. hum biol 42:626-638. baume lj. 1950. physiological tooth migration and its significance for the development of occlusion. ii. the biogenesis of accessional dentition. j dent res 29:331-337. bergström k. 1977. an orthopantomographic study of hypodontia, supernumeraries and other anomalies in school children between the ages of 8-9 years. an epidemiological study. swed dent j 1:145-157. bishara se. 1998. clinical management of impacted maxillary canines. semin orthod 4:87-98. böhn a. 1963. dental anomalies in harelip and cleft palate. acta odontol scand suppl 38:1-109. cobourne mt. 2007. familial human hypodontia—is it all in the genes? br dent j 203:203-208. demirjian a, goldstein h, tanner jm. 1973. a new system of dental age assessment. hum biol 45:211227. dolder e. 1937. deficient dentition: statistical survey. dent record 57:142-143. egermark-eriksson i, lind v. 1971. congenital numerical variation in the permanent dentition. d. sex distribution of hypodontia and hyperodontia. odontol revy 22:309-315. fitzgerald lr. 1973. deciduous incisor teeth of the mouse (mus musculus). arch oral biol 18:381-389. fukuta y, totsuka m, takeda y, yamamoto h. 2004. congenital absence of the permanent canines: a clinico-statistical study. j oral sci 46:247-252. garn sm. 1977. genetics of tooth development. in: mcnamara ja, editor. the biology of occlusal development. ann arbor, mi: craniofacial growth series, p. 61-88. harris ef. 2002. dental development and anomalies in craniosynostosis and facial clefting. in: mooney mp, siegel mi, editors. understanding craniofacial anomalies: the etiopathogenesis of craniosynostosis and facial clefting. new york: john wiley-liss, p 425467. harris ef, clark ll. 2008. an epidemiological study of hyperdontia in american blacks and whites. angle orthod 78:460-465. harris ef, corruccini rs. 2008. quantification of dental occlusal variation: a review of methods. dental anthropology 21:1-11. harris ef, hullings jg. 1990. delayed dental development in children with isolated cleft lip and palate. arch oral biol 35:469-473. higuchi kw. 2000. orthodontic applications of osseointegrated implants. chicago: quintessence publishing company, inc. huggare j. 1984. congenital aplasia of four permanent cuspids: a case report. proc finn dent soc 80:257259 itin ph, fistarol sk. 2004. ectodermal dysplasias. am j med genet c semin med genet 131c:45-51. kaste sc, hopkins kp. 1994. micrognathia after radiation a.s. smith and e.f. harris 59congenital absence of maxillary permanent canines therapy for childhood facial tumors. oral surg oral med oral path 77:1:95-99. kaste sc, hopkins kp, jones d, crom d, greenwald ca, santana vm. 1997. dental abnormalities in children treated for acute lymphoblastic leukemia. leukemia 11:792-796. klein od, minowada g, peterkova r, kangas a, yu bd, lesot h, peterka m, jernvall j, martin gr. 2006. sprouty genes control diastema tooth development via bidirectional antagonism of epithelialmesenchymal fgf signaling. dev cell 11:181-190. larmour cj, mossey pa, thind bs, forgie ah, stirrups dr. 2005. hypodontia—a retrospective review of prevalence and etiology. part i. quintessence int 36:263-270. matalova e, fleischmannova j, sharpe pt, tucker as. 2008. tooth agenesis: from molecular genetics to molecular dentistry. j dent res 87:617-623. mattheeuws n, dermaut l, martens g. 2004. has hypodontia increased in caucasians during the 20th century? a meta-analysis. eur j orthod 26:99-103. moorrees cfa. 1959. the dentition of the growing child. cambridge: harvard university press. moss-salentijn l. 1978. vestigial teeth in the rabbit, rat and mouse; their relationship to the problem of lacteal dentitions. in: butler pm, joysey ka, editors. development, function and evolution of teeth. london: academic press inc, p 13-29. mostowska a, kobielak a, trzeciak wh. 2003. molecular basis of non-syndromic tooth agenesis: mutations of msx1 and pax9 reflect their role in patterning human dentition. eur j oral sci 111:365-370. peterková r, peterka m, viriot l, lesot h. 2002. development of the vestigial tooth primordia as part of mouse odontogenesis. connect tissue res 43:120128. peters h, neubüser a, kratochwil k, balling r. 1998. pax9-deficient mice lack pharyngeal pouch derivatives and teeth and exhibit craniofacial and limb abnormalities. genes dev 12:2735-2747. pindborg jj. 1970. pathology of the dental hard tissues. san francisco: wb saunders company. polder bj, van’t hof ma, van der linden fp, kuijpersjagtman am. 2004. a meta-analysis of the prevalence of dental agenesis of permanent teeth. community dent oral epidemiol 32:217-226. postello dr. 1984. congenitally missing maxillary canines: a report of two cases. ont dent 61:10-12. pui ch. 1999. acute lymphoblastic leukemia. in: gr lee. wintrobe’s clinical hematology. baltimore: williams & wilkins, p 1141-1153. ranta r. 1983. hypodontia and delayed development of the second premolars in cleft palate children. eur j orthod 5:145-148. ranta r. 1986. a review of tooth formation in children with cleft lip/palate. am j orthod dentofac orthop 90:11-18. rantanen av. 1967. the age of eruption of the third molar teeth. acta odont scand 25:1-86. richardson g, russell ka. 2000. a review of impacted permanent maxillary cuspids—diagnosis and prevention. j can dent assoc 66:497-501. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 1975;68:157-164. satokata i, maas r. 1994. msx1 deficient mice exhibit cleft palate and abnormalities of craniofacial and tooth development. nat genet 6:348-356. schalk-van der weide y. 1992. oligodontia: a clinical, radiographic and genetic evaluation. utrecht: rijksuniversiteit utrecht. scott gr. 1977. lingual tubercles and the maxillary incisor-canine field. j dent res 56:1192. stefan vh. 2006. rotation of the maxillary premolars: evidence in support of premolar morphogenetic field. dental anthropology 70:19:70-82. turner cg 2nd. 1969. directionality in the canine field model. j dent res 48:1310. uslenghi s, liversidge hm, wong fs. 2006. a radiographic study of tooth development in hypodontia. arch oral biol 51:129-133. vieira ar. 2003. oral clefts and syndromic forms of tooth agenesis as models for genetics of isolated tooth agenesis. j dent res 82:162-165. weathersby mg. 2006. dental maturation in children treated for acute lymphoblastic leukemia. m.d.s. thesis, university of tennessee, memphis. zucchero tm, cooper me, maher bs, daack-hirsch s, nepomuceno b, ribeiro l, et al. 2004. interferon regulatory factor 6 (irf6) gene variants and the risk of isolated cleft lip and palate. n engl j med 351:769780. liversidge and rogers 2001.1 pg 1.jpg pg 2.jpg pg 3.jpg pg 4.jpg pg 5.jpg pg 6.jpg brook et al. 2006.3 2� in studying variation between populations tooth crown size is a valuable parameter of dental development (keiser, 1990). crown size is a continuous variable, which is multifactorially determined by both genetic and environmental factors (brook, 1984). however, in seeking to determine tooth crown size in ancient populations, extensive attrition is a complicating factor. attrition may vary from one population to another and in different periods of time (molnar, 1971; brothwell, 1989). archeological populations appear to show a more regular increase in attrition with age than do modern populations with males tending to have higher attrition scores than females (solheim, 1998). therefore, in an earlier population to establish tooth size and to investigate the progress of attrition it is necessary to have sufficient suitable material for various age groups and for both sexes. the romano-british skeletal material from poundbury, dorset, united kingdon, fulfils these requirements. this study aimed to determine the initial mesiodistal tooth crown size and to measure the extent of progressive approximal attrition by determining mesiodistal crown dimensions in different age groups in this romano-british sample. approximal attrition and permanent tooth crown size in a romano-british population a. h. brook,* c. underhill, l. k. foo, m. hector school of clinical dentistry, sheffield, and st bartholomews and the london dental school, london, united kingdom *correspondence to: a. h. brook, school of dental studies, edwards building, university of liverpool, pembroke place, liverpool l69 3gn, united kingdom. e-mail: a.h.brook@liverpool.ac.uk materials and methods excavation of a romano-british christian cemetery, which was in use from ad 200-400, provided the material used in this study. the excavated skeletons of this homogeneous population are housed in the british museum (natural history), london. the sex determination and age estimation of 650 adult specimens had been carried out by staff of the british museum. to estimate age at death the methods of brothwell (1963) and miles (1963a,b) were applied. adult males (n = 310) and adult females (n = 339) had been placed in the four age groups of 14-24 years, 25-34 years, 35-45 years, and over 45 years. skulls for the current study were selected from those with intact or nearly intact dentitions using random number tables. for the tooth size study 30 male and 30 female skulls abstract the aim was to measure mesiodistal crown size of both sexes in different age groups of a well characterised romano-british population to determine the progressive effects of approximal attrition. from the collection in the british museum of romanobritish skeletons excavated from poundbury, aged and sexed by museum staff on established criteria, two samples were selected randomly from those with intact permanent dentitions. the first examiner measured the teeth of 30 males and 30 females aged 14-24 years and the second examiner those of 59 males and 51 females distributed across the four age groups, namely 14-24, 25-34, 35-45, over 45 years. the mesiodistal diameter of each permanent tooth was measured on two separate occasions and the mean for each tooth type in each age group calculated. differences were explored with two sample t-tests and multiple regression analysis. the intra-operator reproducibility for difference tooth types ranged from r = 0.92 to r = 0.99 and for inter-operator reproducibility from r = 0.74 to r = 0.99. in the youngest age group males had larger teeth than females with this difference being statistically significant for most tooth types. there was a pattern of decreasing tooth size over the four age groups, with males more affected than females. different tooth types showed different reductions, the greatest being in upper and lower incisors and upper first molars and the least in lower second molars, upper second molars and third molars. the average total arch length reduction estimated by two different methods between aged groups 1 and 4 was 10.0 mm in the upper jaw and 6.4 mm in the lower jaw. thus, in this romano-british sample all tooth types showed reduction in mesiodistal diameter with increasing age, the extent varying between the sexes, the jaws and tooth types. from comparable studies, this approximal attrition was slightly greater than for mediaeval swedes and considerably greater than modern swedes and other caucasians. dental anthropology 2006;19(1):23-28. 24 were selected from the youngest age group and were measured by examiner one (lkf). for the attrition study approximately equal numbers were randomly selected from each of the four age groups (table 1) and were measured by examiner two (cau). excluded from the study were teeth with caries or fractures involving an approximal surface, hypoplasia, rotations, or gross supragingival calculus. the mesiodistal diameters of the teeth were measured using dial calipers (mitutuyo, japan) and the criteria of moorrees et al. (1957). each dentition was measured on a second occasion several days later without access to the initial measurement. the mean of the two measurements was then used in the results. before commencement of the study the two examiners underwent training. the reproducibility was determined by remeasurement of 20 skulls selected using a random number taken on three occasions over 10 weeks. the intra-operator reproducibility for different tooth types ranged from r = 0.92 to r = 0.99. inter-operator reproducibility ranged from r = 0.74 to r = 0.99. for the main study, the differences between mean measurements in each age group were examined for statistical significance using two sample t-tests. in order to take into account fluctuations across age groups related to numbers in each cell and sex differences, three-way multiple regression was also carried out for all individual teeth. table 1. the number of skulls measured in each age group by sex examiner 2 examiner 1 age groups 14-24 years 14-24 yrs 25-34 yrs 35-45 yrs over 45 yrs total male 30 male 10 20 16 13 59 female 30 female 12 17 13 9 51 total 60 total 22 �� 29 22 110 table 2. the mesiodistal crown diameters obtained by two examiners obtained for 2 samples from age group1 male female examiner 1 examiner 2 examiner 1 examiner 2 tooth n x sd n x sd n x sd n x sd u1 24 8.41 0.48 16 8.43 0.32 30 8.15 0.45 17 7.80 0.34 u2 42 6.64 0.56 19 6.57 0.40 49 6.23 0.53 19 6.43 0.37 u3 49 7.63 0.38 20 7.60 0.33 51 7.28 0.40 17 7.28 0.22 u4 50 6.50 0.49 19 6.48 0.35 47 6.28 0.40 17 6.26 0.29 u5 44 6.39 0.45 19 6.16 0.44 40 6.10 0.36 19 6.05 0.28 u6 47 10.05 0.66 20 9.94 0.45 44 9.66 0.40 24 9.45 0.40 u7 45 9.35 0.39 21 9.41 0.59 45 9.08 0.47 23 9.11 0.59 u8 37 8.37 0.78 13 8.77 0.95 31 8.54 0.89 14 8.58 0.78 l1 14 5.15 0.37 22 5.11 0.24 23 4.99 0.36 19 4.96 0.25 l2 26 5.83 0.43 21 5.77 0.33 36 5.55 0.36 20 5.53 0.37 l3 41 6.63 0.48 20 6.68 0.32 46 6.29 0.37 20 6.30 0.21 l4 43 6.73 0.51 19 6.65 0.34 52 6.54 0.40 21 6.37 0.30 l5 42 6.64 0.50 18 6.63 0.35 43 6.48 0.47 23 6.51 0.38 l6 47 11.15 0.61 17 10.99 0.50 50 10.60 0.54 24 10.53 0.34 l7 45 10.43 0.63 20 10.49 0.38 51 10.12 0.71 20 10.16 0.54 l8 32 10.31 0.77 14 10.58 0.77 37 9.85 0.97 13 10.20 0.52 1n = number of teeth measured x = average mesiodistal tooth diameter (mm) sd = standard deviation a.h. brook et al. 25 t a b l e 3 . t he m ea n m es io di st al d ia m et er s of e ac h to ot h ty pe in fo u r di ff er en t ag e ca te go ri es ( m m ) an d th ei r st an da rd d ev ia ti on s a ge g ro u p 1 424 a ge g ro u p 2 534 a ge g ro u p 3 545 a ge g ro u p o v er 4 5 m al e fe m al e m al e fe m al e m al e fe m al e m al e fe m al e to ot h x sd x sd x sd x sd x sd x sd x sd x sd u 1 8. 42 0. 30 7. 87 0. 34 8. 26 0. 60 8. 22 0. 43 7. 47 0. 87 7. 60 1. 16 7. 01 1. 08 7. 07 1. 20 u 2 6. 57 0. 40 6. 43 0. 37 6. 53 0. 78 6. 12 0. 58 6. 02 0. 82 6. 35 0. 59 5. 75 0. 78 5. 53 0. 95 u 3 7. 60 0. 32 7. 28 0. 24 7. 54 0. 50 7. 38 0. 37 7. 36 0. 42 7. 08 0. 52 6. 94 0. 73 6. 64 0. 78 u 4 6. 48 0. 35 6. 26 0. 29 6. 43 0. 40 6. 23 0. 38 6. 25 0. 60 6. 46 0. 46 5. 90 0. 93 5. 60 1. 00 u 5 6. 16 0. 43 6. 06 0. 28 6. 26 0. 45 5. 90 0. 29 6. 27 0. 69 6. 19 0. 43 5. 70 0. 93 6. 02 0. 60 u 6 9. 90 0. 45 9. 45 0. 40 10 .0 1 0. 53 9. 68 0. 39 9. 26 0. 85 9. 90 0. 42 7. 82 0. 49 9. 00 0. 34 u 7 9. 40 0. 59 9. 10 0. 60 9. 47 0. 60 8. 94 0. 67 8. 99 0. 39 9. 10 0. 57 8. 65 0. 97 8. 80 0. 52 u 8 8. 78 0. 95 8. 58 0. 79 8. 47 0. 63 8. 47 0. 80 8. 26 0. 38 8. 30 0. 98 8. 70 0. 90 8. 28 0. 58 l 1 5. 11 0. 25 4. 96 0. 25 5. 11 0. 40 5. 00 0. 45 4. 25 0. 67 4. 70 0. 59 4. 22 0. 74 4. 18 0. 49 l 2 5. 77 0. 32 5. 53 0. 37 5. 70 0. 35 5. 69 0. 40 5. 20 0. 60 5. 48 0. 44 5. 09 0. 63 4. 90 0. 57 l 3 6. 68 0. 31 6. 30 0. 21 6. 70 0. 39 6. 42 0. 30 6. 63 0. 49 6. 30 0. 32 6. 46 0. 55 5. 90 0. 47 l 4 6. 65 0. 34 6. 37 0. 30 6. 60 0. 35 6. 33 0. 48 6. 46 0. 56 6. 25 0. 40 6. 20 0. 62 6. 36 0. 35 l 5 6. 62 0. 35 6. 50 0. 38 6. 60 0. 40 6. 34 0. 41 6. 42 0. 50 6. 26 0. 50 6. 24 0. 64 6. 27 0. 66 l 6 10 .9 9 0. 49 10 .5 0 0. 34 11 .2 0 0. 50 10 .5 1 0. 60 11 .1 8 0. 60 10 .7 0 0. 77 10 .4 9 0. 60 10 .2 0 0. 89 l 7 10 .4 8 0. 37 10 .1 6 0. 55 10 .5 4 0. 64 9. 99 0. 55 10 .5 0 0. 73 10 .2 6 0. 98 9. 99 0. 57 10 .3 0 0. 69 l 8 10 .5 8 0. 77 10 .2 0 0. 14 10 .7 5 0. 68 10 .1 6 0. 90 10 .3 5 0. 90 10 .2 7 0. 78 10 .3 9 0. 70 9. 70 0. 78 x = a v er ag e m es io d is ta l d ia m et er ( m m ) sd = s ta n d ar d d ev ia ti on 26 results since there was no significant difference for individual tooth type between the findings from different sides of the mouth, right and left side measurements were pooled in these results. in table 2 the means and standard deviations of the mesiodistal crown diameters of each tooth type for age group 1, the 14-24 year olds, are given for the sample measured by examiner 1 and that measured by examiner 2. for almost all tooth types the measurements differed by less the 0.2 mm between the two examiners. the mean mesiodistal measurements for male teeth are larger than for females for all tooth types and this difference is statistically significant for upper central incisors, canines, first and second molars and for lower lateral incisors, canines, first and second molars. in table � the means and standard deviations of the mesiodistal crown diameters of each tooth type in the four different age categories determined by examiner 2 are given. the standard deviations of the means tend to be larger in the older age groups. these standard deviations are also greater for posterior compared to anterior teeth. however, they are similar for males and females in each age category. these “raw” figures show a pattern of decreasing tooth size over the four age groups, this trend being greater in males. to investigate these changes further in table 4 the differences between mean mesiodistal crown diameters at ages 14-24 years and over 45 years are given. for all tooth types except the lower second molar in females, the mesiodistal diameter is smaller in age group 4 than in age group 1. using a two sample t-test this difference is statistically significant to varying degrees for all tooth types except the upper second premolar, the upper third molar and the lower first and third molars (table 4). the greatest reductions were in the upper and lower incisors, the upper canines and upper first molars. in table 5 the outcome of the multiple regression analysis is given. this confirms the decrease in mesiodistal crown diameters with increasing age. this decrease was significant with this analysis as indicated by the t ratio for the age group coefficient, in all upper teeth except the second premolar (u5) and third molar (u8) and all the lower teeth except the molars (l6, l7 table 4. difference between the average mesiodistal crown diameters (mm) at age group 1 and age group 4 for males (column 1), females (column 2), and pooled male and female data (column 3)1 difference between mean mesiodistal crown diameters for age group 1 and age group 4 difference regression pooled between male equation tooth male female sexes and female estimation u1 1.41*** 0.81* 1.11*** +0.60 1.25 u2 0.81** 0.90* 0.86*** -0.10 0.80 u3 0.67** 0.64** 0.65*** +0.03 0.66 u4 0.53 0.62* 0.65** -0.08 0.47 u5 0.46 0.03 0.24 +0.43 0.20 u6 2.12*** 0.44* 1.28*** +1.68 0.89 u7 0.76 0.32 0.54* +0.45 0.46 u8 0.08 0.30 0.19 -0.22 0.27 l1 0.89*** 0.78*** 0.84*** +0.11 0.96 l2 0.68*** 0.58** 0.63*** +0.10 0.69 l3 0.22 0.38** 0.30* -0.16 0.30 l4 0.44* 0.01 0.22* +0.43 0.24 l5 0.38* 0.24 0.31* +0.14 0.34 l6 0.50 0.33 0.41 +0.17 0.22 l7 0.49* -0.18 0.16 +0.67 0.11 l8 0.19 0.48 0.33 -0.29 0.36 1 the difference between male and female difference is also given in (column 4). the mesiodistal tooth reduction as estimated by the regression equation has also been included for comparative purposes (column 5) *significant at 5% level **significant at 1% level ***significant at 0.1 level a.h. brook et al. 2� and l8). the multiple regression analysis also indicates the tendency for female teeth to be smaller than male was significant, as shown by the t ratio for the sex coefficient, for all lower teeth except the incisors and for the upper canine and second molar. the total reduction in mesiodistal diameter for each tooth from age group 1 (14-24 years) to age group 4 (over 45 years) can be estimated by multiplying the age group coefficient by three. the totals estimated by this method are given in table 4. the totals for each tooth from the last column in table 4 can then be added together and this figure doubled, to estimate a total upper and lower arch length reduction of 10 mm and 6.4 mm, respectively. an alternative way of using the data to estimate the total reduction in mesiodistal tooth diameter is to subtract the average measurements of teeth in age group 4 from those in age group 1. table 4 also gives the results obtained by this second method. the table confirms that the reduction in diameter is usually greater in males. when the average of the male-female difference is compared with the reduction estimated from the regression equation, the two estimations are within 0.15 mm, except for the upper lateral incisor, upper first molar and lower first molar, where they are greater when estimated by the second method, and the upper central incisors, where they are smaller. the total upper and lower arch reductions estimated by the second method are 10.9 mm and 6.4 mm, respectively. discussion it was important that the gender of the skeletons was determined prior to tooth measurement, because if, for example, a far larger number of female teeth were included in a particular age group, measurements would tend to be reduced due to the sexual dimorphism of tooth size. this would also tend to distort the estimates of mesiodistal attrition gained by comparing dimensions. it is possible that this may have occurred in some previous studies where the sex of the skeletal remains was not specified. mortality amongst young females in earlier populations was high, possibly from childbirth, but also from neglect compared to boys (farwell and molleson, 1993). therefore skulls from such populations where the third molar is just erupting may more frequently be female. small numbers of certain tooth types were included in age group 4, age over 45 years, because only a limited number of skulls were available for selection and many of these did not satisfy the criteria for inclusion. whilst caution is necessary in interpreting results from small numbers, the multiple regression analysis did take this into account. the finding that measurements for mesiodistal crown diameters for the youngest age group, 14-24 year, gave closely similar results for the two samples and the two operators suggests that the data obtained are reliable. while some mesiodistal wear may have occurred even in this group it is unlikely to have yet made any significant differences to those dimensions. supporting this contention there were no significant differences between age groups 1 and 2. in the present study there was a statistically significant change in diameter between age groups 1 and 4 (table 4). this reduction in mesiodistal size is associated with marked occlusal attrition in age group 4, and can be ascribed to approximal attrition. in a sample of 97 mediaeval swedish skulls lysell (1958a,b) showed a comparable reduction in mesiodistal tooth diameters between “juvenile” and “mature” age groups. also in the present study it was seen that these reductions were greater in some tooth types than others (table 4). similarly lysell’s (1958a,b) results show different interproximal attrition in different tooth types. in lysell’s (1958a,b) study the teeth showing the greatest approximal wear are the upper and lower incisors and the upper first molars. while these teeth were also markedly affected in the present study, so also were the upper and lower canines and, to a lesser extent the premolars (table 4). as an explanation for table 5. t-values of multiple regression analysis1 tooth female-male age group tooth female-male age group u1 ns -6.50* l1 ns -7.88* u2 ns -4.90* l2 ns -6.53* u3 3.29* -5.89* l3 6.36* -3.55* u4 ns -3.42* l4 2.81* -2.49* u5 ns l5 2.03* -3.17* u6 ns -4.86* l6 5.68* ns u7 2.55* -2.72* l7 3.37* ns u8 ns l8 2.73* ns 1where t value not quoted, value was below 2 and was not significant 28 this pattern and therefore time in occlusion may be considered. however, against this suggestion is the fact that in the present study and lysell’s (1958a,b) the lower first molars were not significantly affected, and in the present study the later erupting canines were more affected. therefore, considering the patterns shown in tables 4 and 5, it seems probably that a more complex etiology for the attrition must be considered as well as time lapsed since eruption. there are a series of factors affecting attrition (hillson, 1996). these include masticatory forces, non-chewing parafunctions, the use of teeth as tools and the nature of the diet. the combined effects of lateral, anteroposterior and axial forces during mastication result in complex movements of one approximal surface against another. the magnitude and duration of these masticatory forces is added to by such non-chewing use as bruxism, which may occur in some individuals when asleep or unconsciously whilst awake. in addition a tough fibrous diet required heavy prolonged mastication and the abrasiveness of diets in early populations containing barley or rye was increased by the incorporation of grit from hand grinding using stone querns. the people of poundbury had large jaws and edge to edge occlusion; they ate coarse food that required prolonged chewing (farwell and molleson, 1993). they probably had an agricultural life style fulfilling the criteria of hinton (1981) with cereals as the predominant element in the diet. interesting facets arising from the present study are the sex difference in the degree of approximal attrition and the pattern across tooth types, which contrasts with that for occlusal attrition for this population described by whittaker et al. (1982). for the mesiodistal crown diameters of all tooth types in age group 1, female measurements were smaller than male measurements (table 2). however in age group 4, over 45 years, only the lower canine is statistically significantly smaller in the female and for several tooth types, namely the upper central incisor, second premolar and first and second molars and the lower premolars and second molar, the sex difference is reversed (table 3). these findings suggest that males exhibit greater approximal attrition than females overall, although the extent of this difference varies between the different tooth types (tables 4 and 5). conclusions in these romano-britons there is a progressive pattern of approximal attrition with increasing age. this attrition was greater in males than females and varied among different tooth types. the estimated total arch length reduction was comparable for the two methods used and was slightly greater than some other historical populations. the etiology of the attrition is multifactorial and reflects the lifestyle of this population. this study has also illustrated the importance of sampling and establishment of a baseline group for comparisons. acknowledgements we are grateful for the support of theya molleson and for access to the material at the british museum (natural history). also, david whittaker was generous with his advice and encouragement. literature cited brook ah. 1984. a unifying aetiological explanation for anomalies of human tooth number and size. arch oral biol 29:373-378. brothwell dr. 1963. digging up bones. london: trustees of the british museum, p 57-70. brothwell dr. 1989. the relationship of tooth wear to aging. in: iscan my, editor. age markers in the human skeleton. springfield: cc thomas, p 303-316. farwell de, molleson tl. 1993. excavations at poundbury 1966-80, vol 2: the cemeteries. dorchester, uk: friary press, p 171-186. hillson s. 1996. dental anthropology. cambridge: cambridge university press, p 231-253. hinton rj. 1981. form and patterning of anterior tooth wear among aboriginal human groups. am j phys anthropol 54:555-564. keiser ja. 1990. human adult odontometrics. cambridge: cambridge university press, cambridge, p 10-12. lysell l. 1958a. a biometric study of occlusion and dental arches in a series of medieval skulls from northern sweden. acta odontol scand 16:177-180. lysell l. 1958b. quantitative and qualitative determination of attrition and the ensuing tooth migration. acta odontol scand 16:267-293. miles aew. 1963a. the dentition in the assessment of individual age. in: brothwell dr, editor. dental anthropology. oxford: pergamon press, p 191-209. miles aew. 1963b. dentition in the estimation of age. j dent res 42:255-263. molnar s. 1971. human tooth wear, tooth function and cultural variability. am j phys anthropol 34:175190. moorrees cfa, yen pk. 1957. mesiodistal crown diameters of the deciduous and permanent teeth in individuals. j dent res 36:39-47. solheim t. 1996. degeneration in dental hard tissues and pulp. in: alt kw, rosing fw, teschler-nicola m, editors. dental anthropology: fundamentals, limits and prospects. new york: springer wein, p 469-478. whittaker dk, parker jh, jenkins c. 1982. tooth attrition and continuing eruption in a romano-british population. arch oral biol 27:405-408. a.h. brook et al. florez et al 2006.5 83 dental morphology trait expressions have been used in anthropology and forensic sciences for determination of biological and geographical affiliations. variations in morphology of crowns may be manifest in the primary and/or permanent dentitions. dental variation is heritable, is caused by multiple genes, and is little influenced by environmental factors. traditionally, three, four, five, six or seven cusps, specifically the protoconid, metaconid, hypoconid, rntoconid, hypoconulid, entoconulid and metaconulid, have been reported in morphological descriptions of lower molars for various human groups (axelsson and kirverskari, 1979; devoto and perroto, 1972; hanihara, 1967; harris and bailit, 1980; morris, 1965; sciulli, 1977; schroeder et al., 1983; scott and turner 1997; suzuki and sakai, 1973). this brief communication reports on the presence and asymmetry of a possible eighth cusp on mandibular primary second molars of a contemporary argentinean boy. materials and methods the teeth of a racially mixed boy five years of age from cordoba city, argentina, were examined in situ and on a plaster cast. an unusually shaped accessory occlusal cusp was observed on both the left and right mandibular primary second molars. size of this eighth cusp was measured with sliding calipers. this case report is part of an anthropological study carried out on material provided by the departamento de ortodoncia, facultad de odontología, universidad nacional de cordoba, argentina. brief communication: occurrence of an eighth cusp on primary second mandibular molars of a contemporary argentinean child carlos david rodríguez florez1*, gabriel mario fonseca2, and maria teresa de villalba3 1cátedra de antropología biológica y cultural, facultad de ciencias exactas, físicas y naturales, 2cátedra de anatomía patológica b, facultad de odontología, and 3cátedra de ortodoncia, facultad de odontología universidad nacional de córdoba, argentina. grant sponsor: facultad de odontología, universidad nacional de córdoba, argentina. *correspondence to: carlos david rodríguez florez, cátedra de antropología biológica y cultural, facultad de ciencias exactas, físicas y naturales universidad nacional de córdoba, argentina. e-mail: david@syllabapress.com abstract: the presence and asymmetry of an eighth cusp observed on the primary second mandibular results figures 1 and 2 illustrate the presence and bilateral asymmetry observed on mandibular primary second molars. a small additional cusp occurs between hypoconulid and entoconulid cusps. the anomalous cusp is larger on the right molar (diameter: 0.245 mm) than the left (diameter: 0.165 mm). discussion this accessory, eighth cusp has been not reported previously. this rare variant on anomalous lower primary molars provides an interesting record of eighth cusp in human dental morphology. bilateral presence and asymmetrical appearance of the eighth cusp suggest a possible factor of heritability in the expression of this infrequently human molar form. brabant suggests that primary second mandibular molars with five cusps are most common. six cusps are less frequent (2% to 30%), and the seven-cusp molar—with a cusp of jørgensen (metaconulid)—is found in less than 10% of cases (brabant, 1967). kallay’s (1966) classification molars of an argentinean boy is described. dental anthropology 2006;19(3):83-85. 84 could be used to label this eighth cusp, perhaps the protuberantio apulparis sited in the distal occlusal area of primary second lower molars. as mentioned by brothwell (1967), the phenomenon of increasing world contact, immigration, and interbreeding between previously more isolated communities can produce new forms that enrich the variation observed in the human dentition. literature cited axelsson g, kirveskari p. 1979. sixth and seventh cusp on lower molar teeth of icelanders. am j phys anthropol 51:79-82. brabant h. 1967. comparison of the characteristics and anomalies of the deciduous and the permanent dentition. j dent res 46:897-902. brothwell dr. 1967. some problems and objectives related to the study of dental variation in human populations. j dent res 46:938-941. devoto fch, perroto bm. 1972. groove pattern and cusp number of mandibular molars from tastilian indians. j dent res 51:205. hanihara k. 1967. racial characteristics in the dentition. j dent res 46:923-926. harris ef, bailit hl. 1980. the metaconule: a morphologic and familial analysis of a molar cusp in humans. am j phys anthropol 53:349-358. kallay j. 1966. extra cusp formation in the human dentition. j dent res 45:1381-1394. morris dh. 1965. the anthropological utility of dental morphology. ph.d. dissertation, department of anthropology, university of arizona. tucson, az. sciulli pw. 1977. a descriptive and comparative study of the deciduous dentition of prehistoric ohio valley amerindians. am j phys anthropol 46:71-80. fig. 1. occlusal view of case (in situ). c. d. rodriguez-florez et al. 85eight cusps on primary mandibular molars schroeder k, zacherl w, paulson r, gaston p, sciulli pw. 1983. cusp tip abnormalities in the deciduous and permanent dentitions. j dent res 62:224. scott gr, turner ii cg. 1997. the anthropology of modern human teeth. cambridge: cambridge university press. suzuki m, sakai t. 1973. occlusal surface pattern of the lower molars and the second deciduous molar among the living polynesians. am j phys anthropol 39:305-315. fig. 2. occlusal view of the mandibular second molars as seen on the plaster cast. tocheri 2002.1 1 this paper tests the validity of the latter three assumptions as they relate to deciduous dental morphology. in turn, this sheds light on the first two assumptions. establishing the utility of deciduous nonmetric traits in human population research is imperative if they are to be used successfully in biological distance analyses. while skeletal samples typically do not consist of a preponderance of juveniles, this is not always the case (fairgrieve and molto, 2000; tocheri and molto, in press). therefore, deciduous nonmetric dental traits offer a valuable alternative source of biological data. in this study, my first objective is to examine the effects of sexual dimorphism on deciduous trait presence and expression. discrete dental traits rarely exhibit sexual dimorphism in the permanent teeth and when they do, it is primarily restricted to a few variants (harris, 1980; nichol, 1990; scott, 1977; turner et al., 1991). theoretically, deciduous traits may be influenced by sex more than permanent traits since all deciduous teeth begin to form in utero. the presence of dihydrotestosterone and other androgens in male embryos act to differentiate them from females beginning around the seventh fetal week (daly and wilson, 1983; mange and mange, 1990). dempsey et al. (1999) studied the permanent teeth of a large sample of twins and singletons (n = 448) and found that females the number of studies dealing with nonmetric variation in human deciduous teeth pale in comparison with those of the permanent dentition (scott and turner, 1997). this discrepancy has been attributed to the paucity of deciduous dental remains at archaeological sites (kitagawa, 2000; sciulli, 1998), their shorter functional life span in comparison with permanent teeth (kitagawa, 2000), and the difficulty in obtaining a set of hanihara’s (1961) reference plaques (mayhall, 1992). several studies, however, indicate that deciduous nonmetric dental traits are useful tools in assessing the biological relationships of human populations (goldstein, 1948; grine, 1986, 1990; hanihara, 1956, 1961, 1963, 1965, 1970; hrdlicka, 1920; johnse, 1947; jorgensen, 1956; lukacs and walimbe, 1984; sciulli, 1977, 1990, 1998; smith, 1976, 1978). a number of fundamental assumptions underpin the use of discrete dental traits in population analyses. these include the following: 1. genes strongly control trait presence and expression 2. environmental influences on trait presence and expression are negligible 3. the effects of sexual dimorphism on trait presence and expression are minimal 4. antimere asymmetry is the result of environmental rather than genetic influences 5. associations between traits are not biologically meaningful the effects of sexual dimorphism, asymmetry, and intertrait association on the distribution of thirteen deciduous dental nonmetric traits in a sample of pima amerindians matthew w. tocheri department of anthropology, arizona state university, tempe az 85287-2402 abstract one hundred dental casts of modern pima amerindian children, 50 male and 50 female, were examined for the presence and expression of thirteen deciduous nonmetric traits. the effects of sexual dimorphism, asymmetry, and inter-trait association on trait presence were examined to evaluate their utility in population distance studies. no statistically significant differences between the sexes were observed. the majority of examined variants displayed a strong trend toward bilateral expression and no statistically significant differences between antimeres occurred. these data support the hypothesis that strong genetic components coupled with negligible environmental influences are involved in deciduous trait presence. five statistically significant associations between variants were detected. four of these involved a combination of incisor and canine shoveling within and between jaws. this indicates that their combined use in biological distance studies violates the mathematical assumption of independence. the lack of significant sexual dimorphism and asymmetry in the deciduous discrete traits examined herein supports their use in population distance analyses if precautions are taken to use non-associated traits. editor’s note: mr. tocheri’s paper was awarded first prize for 2001 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. matthew w. tocheri 2 3 which had a male twin “have consistently larger teeth (on average) than other females” (dempsey et al., 1999: 577). they proposed that these differences were the result of “diffusion of sex hormones from male to female co-twins in utero” (dempsey et al., 1999:577). how these naturally occurring steroids affect the development and expression of primary nonmetric variants is not well understood because few studies have examined sexual dimorphism in these traits. hanihara (1965, 1970) reported that “no differences between sexes has been found” for several deciduous variants; however, he did not discuss any statistical methodology (hanihara, 1965: 136, 1970). grine (1990) examined a sample of kalahari san children and found a lack of statistically significant sexual dimorphism in the deciduous traits he scored. similarly, he found no sex differences in a sample of south african black children (grine, 1986). sex differences, however, may vary between populations in both dental (harris, 1980) and skeletal traits (ossenberg, 1976; molto, 1985). therefore, it is important to document the effects of sex on deciduous trait presence and expression in other human groups. my second objective is to examine asymmetry in trait presence and expression on the anitmeres. asymmetrical studies can reveal information pertaining to the environmental and functional influences on the presence of dental and skeletal discrete traits along with their underlying genotype (mayhall and saunders, 1986; turner, 1985; trinkaus, 1978). several researchers have examined asymmetry in permanent (bailey-schmidt, 1995; baume and crawford, 1980; biggerstaff, 1972; harris, 1977; meredith and hixon, 1954; nichol, 1990) and in primary dental traits (townsend, 1981; townsend and brown, 1980, 1981) and have found it to be a random phenomenon influenced by the environment. a sample size greater than 100 is typically considered appropriate for statistical analyses of asymmetry (garn et al., 1979; smith et al., 1982), however, the documentation of observed trends in smaller samples can aid future research. understanding the associations among deciduous dental traits is necessary to increase their effectiveness in biological distance calculations. associations between cranial nonmetric variables have been shown to adversely affect the calculation of c.a.b. smith’s mean measure of divergence (mmd) (molto, 1985). similar results have been reported for distance analyses using permanent discrete traits (hawkey, personal communication 2000; nichol, 1990). therefore, my final objective is to statistically examine the associations between these thirteen traits and critically evaluate their combined use in population distance studies. materials and methods the sample consisted of 100 deciduous dental casts, 50 male and 50 female, of pima amerindians from southern arizona. all casts were collected from living children by albert a. and thelma dahlberg between 1949 and 1975 and are curated at the dental anthropology laboratory at arizona state university. the age and sex of each individual was recorded at the time of casting. the majority of casts examined in this study represent individuals between 5 and 10 years of age. approximately 60% of their deciduous teeth were present for analysis. thirteen nonmetric traits were scored following the plaques (d series) and written descriptions of hanihara (1961). only teeth unaffected by wear or pathology were scored. a list of the examined traits and a description of how grades were dichotomized into present-absent categories is presented in table 1. hanihara’s (1961) dichotomizing criteria were used for all traits. throughout the text and tables the following abbreviations are used: l, lower; u, upper; i, incisor; c, canine; m, molar; 1, first in tooth series; 2, second in tooth series. twenty dentitions were randomly selected and re-scored on separate occasions. in order to analyze intra-observer reliability, an integral part of any discrete trait study (molto, 1979; nichol and turner, 1986). intra-observer reliability scores are reported by grade, presence/absence per tooth and presence/absence per individual in table 2. scoring consistency was lowest by grade (75%) and highest per individual (92%). i considered the observed scoring consistency by grade to be too low to analyze differences between degrees of expression. therefore, only differences between trait presence and absence are reported herein. per individual, seven out of 13 traits were scored reliably 100% of the time, two between 90-95%, and three between 80-85%. the protostylid (lm2) was the least reliably scored trait (65% per individual). the relative frequencies of each trait were calculated using the individual-count method. this assumes each trait is symmetrical and predominantly controlled by a single genotype; therefore, the strongest expression of the trait in an individual represents that genotype most accurately (scott, 1980; turner and scott, 1977; turner, 1985; turner et al., 1991). differences in trait relative frequency between males and females and also between the right and left sides were analyzed. the pearson chi-square test statistic was used to detect significance (p < 0.05). inter-trait associations were measured using the phi coefficient with p values less than 0.01 considered significant following the recommendations of molto (1985) and sjøvold (1973). in all statistical analyses, if one or more cells had an expected count less than 5, fisher’s exact test was used to examine significance. asymmetry was investigated using the index of bilaterality (bi), calculated by dividing the frequency of bilateral presence by the sum of the frequencies of unilateral and bilateral presence, and multiplying by 100 (molto, 1983). this index reveals the symmetrical 2 3 tendencies of a trait when it is present. in other words, individuals who exhibit bilateral absence of a trait are not included in the calculation of the index. an index value greater than 50 indicates the trait occurs more often bilaterally whereas a value less than 50 indicates it occurs more often unilaterally. results the relative frequencies of each trait by sex and by antimere are shown in tables 3 and 4, respectively. no statistically significant difference between the sexes or between antimeres was observed (p < 0.05). all traits displayed a tendency toward bilateral expression (bi > 50) except for crown pattern (um1; bi = 0), carabelli’s cusp (um2; bi = 40) and distal trigonid crest (lm2; bi = 50) as shown in table 5. five statistically significant (p < 0.01) associations between traits occurred (table 6). the significant association between shoveling (ui1) and crown pattern (um2) is not likely to be biologically meaningful given that they develop in different developmental fields (dahlberg, 1949). the remaining four associations, however, all involved combinations of incisor and canine shoveling within and between jaws. these significant associations strongly suggest a shared developmental pathway and strong genetic component for shoveling in the anterior teeth. discussion my first objective was to analyze the effects of sex on trait relative frequency. of the 13 nonmetric traits examined in this study, none displayed statistically significant sexual dimorphism. this complements the results of alvrus (2000) who found a “fairly low degree of sexual dimorphism” in deciduous metric traits in pima children (alvrus, 2000:12). together, the results of these two studies suggest that, among the pima, sex does not strongly affect the expression of metric or nonmetric deciduous traits. grine (1986, 1990) also found a lack of statistically significant sex differences for kalahari san and south african black children. clearly, sexual dimorphism plays little role in the development of the examined deciduous crown traits within these population samples. my second objective was to analyze trait asymmetry. none of the deciduous variants examined were expressed significantly more often on a particular side. only one difference between antimeres approached statistical significance (crown pattern [um1], p = 0.054), and this is likely attributable to the overall low relative frequency of this trait (4.3%). ten traits were expressed more often bilaterally (bi > 60). the overwhelming tendency toward bilateral expression is consistent with the hypothesis that strong genetic components are involved in dental trait expression (turner et al., 1991). crown pattern (um1) and carabelli’s cusp (um2) were expressed more often unilaterally (bi < 40) while distal trigonid crest occurred bilaterally and unilaterally equally as often (lm2; bi = 50). the unilateral tendency of crown pattern (um1) and carabelli’s cusp (um2) may be the result of their low relative frequency in the study sample (< 5.1%). in sum, these data are consistent with the hypothesis that asymmetry is a random phenomenon representing environmental influences on the underlying genotype (mayhall and saunders, 1986; nichol, 1990; turner, 1985). a fundamental assumption underlying the use of the mmd statistic is that the variables examined are not associated with one another (sjøvold, 1973). therefore, combining dental or skeletal nonmetric traits that are significantly associated violates the assumption of independence (molto, 1985; nichol, 1990). in this study, four statistically significant associations were detected table 1. the trait list and scoring procedure used in this study tooth trait grades scored presence1 ui1 shovel 0, 1, 2, 3 2, 3 ui2 shovel 0, 1, 2, 3 2, 3 uc shovel 0, 1, 2, 3 2, 3 um1 crown pattern 2, 3h1, 3h2, 3m1, 3m2, 4-, 4 4-, 4 um2 crown pattern 3+a, 3+b, 4-, 4 4-, 4 um2 carabelli’s cusp 0, 1, 2, 3, 4, 5, 6, 7 4 7 li1 shovel 0, 1, 2, 3 2, 3 li2 shovel 0, 1, 2, 3 2, 3 lc shovel 0, 1, 2, 3 2, 3 lm2 protostylid 0, 1, 2, 3, 4, 5, 6 2 6 lm2 cusp 7 0, 1, 2, 3 1 3 lm2 central ridge 0, 1 1 lm2 distal trigonid crest 0, 1, 2 1, 2 1follows hanihara’s (1961) dichotomy 4 5 that likely have biological meaning. all involved a combination of incisor and canine shoveling. this trait was associated between ui1-ui2, ui2-uc, ui2-lc, and uc-lc. sciulli (1998) noted: for the total sample and in the woodland and pearson samples, shoveling shows strong associations between anterior teeth. the maxillary incisors are significantly associated with each other but independent of the canines, while the mandibular incisors are associated with each other, the maxillary incisors, and the mandibular canine. shoveling of the maxillary canine is the only feature independent of shoveling in all other anterior teeth [sciulli, 1998:196]. clearly, shoveling in the anterior teeth is likely the result of a similar, if not identical genetic component. if this is true, the combined use of shoveling traits on different teeth in biological distance studies may adversely affect the results of the mmd statistic. molto (1985) demonstrated that using six associated cranial variants (p < 0.015) in a battery of 27 significantly altered the mmd results. nichol (1990) and hawkey (personal communication, 2000) have found similar results using significantly associated permanent discrete traits. molto (1985) aptly summarized: in closing, i would like to emphasize that the concept of distance is a theoretical mathematical concept that has been borrowed and applied to population biology. debate continues as to the meaning and/or legitimacy of distances computed using biological data (sjøvold, 1977). in view of this, the very least researchers can do, is to obey the assumptions outlined by mathematical theory. this means that biological distances should be computed using variates that, except for an acceptable number of chance associations, are statistically independent of each other [molto, 1985:64]. table 2. intra-observer reliability scores for this study per tooth per individual tooth side trait grade1 % p/a2 % p/a3 % ui1 r shovel 15 75 19 95 20 100 l 17 85 20 100 ui2 r shovel 15 75 15 75 20 100 l 19 95 20 100 uc r shovel 15 75 17 85 17 85 l 16 80 17 85 um1 r crown pattern 17 85 20 100 20 100 l 11 55 14 70 um2 r crown pattern 18 90 20 100 20 100 l 17 85 20 100 um2 r carabelli’s cusp 10 50 19 95 20 100 l 12 60 20 100 li1 r shovel 19 95 18 90 18 90 l 18 90 18 90 li2 r shovel 17 85 20 100 20 100 l 15 75 20 100 lc r shovel 18 90 19 95 19 95 l 16 80 19 95 lm2 r protostylid 5 25 10 50 13 65 l 8 40 13 65 lm2 r cusp 7 11 55 15 75 17 85 l 15 75 16 80 lm2 r central ridge 14 70 14 70 16 80 l 15 75 14 70 lm2 r distal trigonid crest 17 85 19 95 20 100 l 18 90 19 95 total 388 75 455 88 240 92 1identical grade was consistently scored per tooth examined (out of 20) 2presence/absence was consistently scored per tooth examined (out of 20) 3presence/absence was consistently scored per individual examined (out of 20) 4 5 table 4. relative frequencies of 13 deciduous dental traits and their distribution by antimere in a pima amerindian sample1-2 total right left tooth trait n % 2n % 2n % p ui1 shovel 53 50.9 53 50.9 50 44.0 0.481 ui2 shovel 73 71.2 66 68.2 71 70.4 0.776 uc shovel 99 42.4 94 36.2 97 40.2 0.566 um1 crown pattern 94 4.3 86 4.7 91 0.0 0.054 um2 crown pattern 97 88.7 94 83.0 95 88.4 0.285 um2 carabelli’s cusp 99 5.1 99 3.0 96 4.2 0.718 li1 shovel 20 5.0 18 5.6 18 5.6 1.000 li2 shovel 43 16.3 38 13.2 39 12.8 1.000 lc shovel 95 74.7 89 73.0 93 66.7 0.350 lm2 protostylid 99 80.8 96 74.0 98 74.5 0.933 lm2 cusp 7 96 70.8 91 65.9 94 61.7 0.549 lm2 central ridge 94 70.2 89 62.9 91 64.8 0.789 lm2 distal trigonid crest 97 28.9 94 19.1 94 24.5 0.377 12n, # of sides; %, relative frequency. 2p, significance level (chi-square or fisher’s exact test). table 3. relative frequencies of 13 deciduous dental traits and their distribution by sex in a pima amerindian sample1-2 total males females tooth trait n % n % n % p ui1 shovel 53 50.9 27 51.9 26 50.0 0.893 ui2 shovel 73 71.2 39 69.2 34 73.5 0.686 uc shovel 99 42.4 49 36.7 50 48.0 0.257 um1 crown pattern 94 4.3 46 4.3 48 4.2 1.000 um2 crown pattern 97 88.7 48 87.5 49 89.8 0.721 um2 carabelli’s cusp 99 5.1 50 2.0 49 8.2 0.204 li1 shovel 20 5.0 14 7.1 6 0.0 1.000 li2 shovel 43 16.3 25 16.0 18 16.7 1.000 lc shovel 95 74.7 47 76.6 48 72.9 0.680 lm2 protostylid 99 80.8 49 83.7 50 78.0 0.474 lm2 cusp 7 96 70.8 49 77.6 47 63.8 0.139 lm2 central ridge 94 70.2 47 72.3 47 68.1 0.652 lm2 distal trigonid crest 97 28.9 48 35.4 49 22.4 0.159 1n, # of individuals; %, relative frequency. 2p, significance level (chi-square or fisher’s exact test). therefore, researchers should be extremely cautious when using a number of deciduous shoveling traits in biological distance analyses. the use of “key” teeth for deciduous variants, as is common practice in permanent discrete trait studies (hawkey, 1998), is recommended. conclusions the nonmetric traits of the deciduous dentition examined herein showed no statistically significant sex or side differences in trait relative frequency. the majority of the traits were expressed bilaterally. together these data suggest the deciduous traits examined are primarily under genetic control with negligible environmental influences involved in their expression. four statistically significant associations between shoveling traits on the anterior teeth were interpreted as representing a shared developmental pathway and genetic component. therefore, using more than one deciduous shoveling trait as part of a trait battery measuring biological distance would violate the mathematical assumption of independence between variables. in sum, the observed lack of significant sexual dimorphism and asymmetry in this study supports the use of deciduous discrete traits 6 7 in population analyses if the necessary precautions are taken involving significant associations between variants. literature cited alvrus a. 2000. sex dimorphism in the deciduous dentition of modern pima. dental anthropology 14:9-13. bailey-schmidt. 1995. population distribution of the tuberculum dentale complex and anomalies of the maxillary anterior teeth. m.a. thesis, arizona state university, tempe. baume rm, crawford mh. 1980. discrete dental trait asymmetry in mexican and belize groups. am j phys anthropol 52:315-321. biggerstaff rh. 1973. heritability of the carabelli cusp in twins. j dent res 52:40-44. dahlberg aa. 1949. the dentition of the american indian. in: ws laughlin ws, editor. the physical anthropology of the american indian. new york: viking fund, p 138-176. daly m, wilson m. 1983. sex, evolution, and behaviour, 2nd ed. belmont, ca: pws publishers. dempsey pj, townsend gc, richards lc. 1999. increased tooth crown size in females with twin brothers: evidence for hormonal diffusion between human twins in utero. am j hum bio 11:577-586. fairgrieve si, molto je. 2000. cribra orbitalia in two temporally disjunct population samples from the dakhleh oasis, egypt. am j phys anthropol 111: 319-331. garn sm, cole pe, smith bh. 1979. the effect of sample size on crown side asymmetry. j dent res 58:2012. goldstein ms. 1948. dentition of indian crania from texas. am j phys anthropol 6:63-84. grine fe. 1986. anthropological aspects of the deciduous teeth of south african blacks. in: singer r, lundy jk, editors. variation, culture and evolution in african populations. johannesburg: witwatersrand university press, p 47–83. grine fe. 1990. deciduous dental features of kalahari san: comparison of non-metrical traits. in: sperber gh, editor. apes to angels: essays in anthropology in honor of philip v. tobias. new york: wiley-liss, p 153-169. hanihara k. 1956. studies on the deciduous dentition of the japanese and the japanese-american hybrids. iii deciduous lower molars. j anthropol soc nippon 64:95. hanihara k. 1961. criteria for classification of crown characters of the human deciduous dentition. j anthrop soc nippon 64:27-45. hanihara k. 1963. crown characters of the deciduous dentition of the japanese-american hybrids. in: brothwell dr, editor. dental anthropology. london: pergamon press, p 104–124. hanihara k. 1965. some crown characters of the deciduous incisors and canines in japaneseamerican hybrids. j anthrop soc nippon 72:135145. hanihara k. 1970. mongoloid dental complex in the deciduous dentition with special reference to the dentition of the ainu. j anthrop soc nippon 78:3-17. harris ef. 1977. anthropologic and genetic aspects of the dental morphology of solomon islanders, melanasia. ph.d. dissertation, arizona state university, tempe. harris ef. 1980. sex differences in lingual marginal ridging on the human maxillary central incisor. am j phys anthropol 52:541-548. hawkey de. 1998. out of asia: dental evidence for affinities and microevolution of early populations from india/sri lanka. ph.d. dissertation, arizona state university, tempe. hrdlicka a. 1920. shovel-shaped teeth. am j phys antable 5. the symmetrical tendencies of 13 deciduous dental traits used in this study trait presence index of symmetrical tooth trait bilateral unilateral bilaterality tendency ui1 shovel 22 3 88.0 bilateral ui2 shovel 43 4 91.5 bilateral uc shovel 31 7 81.6 bilateral um1 crown pattern 0 2 0.0 unilateral um2 crown pattern 76 6 92.7 bilateral carabelli’s cusp 2 3 40.0 unilateral li1 shovel 1 0 100.0 bilateral li2 shovel 3 2 60.0 bilateral lc shovel 56 8 87.5 bilateral lm2 protostylid 64 12 84.2 bilateral cusp 7 50 14 78.1 bilateral central ridge 49 10 83.1 bilateral distal trigonid crest 13 13 50.0 --6 7 thropol 3:429-465. johnse hg. 1947. the primary dentition in homo sapiens and the search for primitive features. am j phys anthropol 5:251-274. jorgensen k. 1956. the deciduous dentition: a descriptive and comparative anatomical study. acta odontol scand 14:1–202. kitagawa y. 2000. nonmetric morphological characters of deciduous teeth in japan: diachronic evidence of the past 4000 years. int j osteoarch 10:242-253. lukacs jr, and walimbe sr. 1984. deciduous dental morphology and the biological affinities of a late chalcolithic skeletal series from western india. am j phys anthropol 65:23–30. mange ap, mange ej. 1990. genetics: human aspects. 2nd edition. sunderland, ma: sinauer associates. mayhall jt. 1992. techniques for the study of dental morphology. in: saunders sr, katzenberg ma, editors. skeletal biology of past peoples: research methods. new york: wiley-liss, inc, p 59-78. mayhall jt, saunders sr. 1986. dimensional and discrete dental trait asymmetry relationships. am j phys anthropol 69:403-411. meredith hv, hixon eh. 1954. frequency, size, and bilateralism of carabelli’s tubercle. j dent res 33: 435-440. molto je. 1979. the assessment and meaning of intraobserver error in population studies based on discontinuous cranial traits. am j phys anthropol 51:333-344. molto je. 1983. biological relationships of southern ontario woodland peoples: the evidence of discontinuous cranial morphology. national museums of canada: ottawa. molto je. 1985. simultaneous occurrence of discontinuous cranial traits: some theoretical and practical considerations for population analyses. can rev phys anthropol 4:57-65. nichol cr. 1990. dental genetics and biological relationships of the pima indians of arizona. ph.d. dissertation, arizona state university, tempe. nichol cr, turner ii cg. 1986. intraand interobserver concordance in classifying dental morphology. am j phys anthropol 69:299-315. ossenberg ns. 1976. within and between race distances in population studies based on discrete traits of the human skull. am j phys anthropol 45:701-716. sciulli pw. 1977. a descriptive and comparative study of the deciduous dentition of prehistoric ohio valley amerindians. am j phys anthropol 47:71–80. sciulli pw. 1990. deciduous dentition of a late archaic population of ohio. hum biol 62:221–245. sciulli pw. 1998. evolution of the dentition in prehistoric ohio valley native americans: ii. morphology of the deciduous dentition. am j phys anthropol 106:189-205. scott gr. 1977. classification, sex dimorphism, association, and population variation of canine distal accessory ridge. hum biol 49:453-469. scott gr. 1980. population variation of carabelli’s trait. hum biol 52:63-78. scott gr, turner ii cg. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. new york: cambridge university press. sjøvold t. 1973. the occurrence of minor non-metritable 6. associations between the 13 deciduous dental traits used in this study1-3 tooth ui1 ui2 uc um1 um2 um2 li1 li2 lc lm2 lm2 lm2 lm2 tooth trait sh sh sh cp cp cc sh sh sh pr c7 cr dtc ui1 sh 0.36 0.17 -0.21 0.39 0.00 -0.05 0.04 0.16 0.19 0.31 -0.06 ui2 sh 0.01 0.41 0.16 0.31 0.02 0.14 0.42 -0.04 0.28 0.03 -0.10 uc sh 0.21 0.00 -0.07 0.04 0.17 0.25 0.26 0.28 -0.05 0.08 0.13 -0.09 um1 cp 0.23 0.31 0.64 0.08 -0.05 0.20 0.13 -0.02 -0.15 -0.02 0.03 um2 cp 0.01 0.02 0.76 1.00 0.08 0.12 0.19 0.24 -0.09 -0.09 0.05 -0.13 um2 cc 1.00 1.00 0.16 1.00 1.00 -0.10 -0.09 -0.12 -0.06 0.16 -0.15 li1 sh 0.45 1.00 1.00 -0.40 0.13 0.10 -0.39 -0.14 li2 sh 1.00 0.64 0.11 0.32 0.57 1.00 0.05 0.09 -0.04 0.12 -0.14 0.00 lc sh 0.79 0.00 0.01 0.57 0.03 0.59 0.25 1.00 0.13 -0.03 -0.06 0.11 lm2 pr 0.29 1.00 0.66 1.00 0.68 0.25 1.00 1.00 0.24 0.16 -0.03 -0.03 lm2 c7 0.18 0.02 0.42 0.21 0.50 0.62 1.00 0.65 0.78 0.12 0.23 0.05 lm2 cr 0.02 0.81 0.21 1.00 0.73 0.32 0.26 0.39 0.61 0.81 0.02 0.05 lm2 dtc 0.68 0.42 0.37 1.00 0.29 0.32 1.00 1.00 0.29 0.80 0.63 0.60 1sh, shovel; cp, crown pattern; cc, carabelli’s cusp; pr, protostylid; c7, cusp 7; cr, central ridge; dtc, distal trigonid crest. 2phi coefficients are above the main diagonal; p values are below the main diagonal. 3bolded values are statistically significant at the 0.01 level. 8 9 skeletal anthropology program opening january 2003 department of anthropological sciences universidad autónoma de yucatán, mérida the department of anthropological sciences of the universidad autónoma de yucatán, mérida, offers a new program in skeletal anthropology leading to a certificate or forming part of a m.s. in anthropological sciences. the program is oriented to graduate students, professors and other professionals interested in bioarchaeology (archaeology, physical anthropology, forensic sciences, and biology). the program offers a firm background in the theory, methodology , fieldwork and laboratory research. it is designed to train qualified professionals and broaden their range of job opportunities, or open the door for students towards doctorate programs in anthropology. the program the program encompasses three quarters. the curriculum revolves around theory, methodology and practical applications. along with the department facilities, the program will benefit from a specialized lab and on-going research projects based on several skeletal collections of the region. the lab is fully equipped for up-to-date bone histomorphology in addition to standard osteological and dental analyses. primary faculty are dr. vera tiesler and dr. andrea cucina admission applicants must apply directly to the department. in addition to general graduate admission requirements of the uady, applicants must: • hold a b.a. or b.s. degree with a major in anthropolgy, social, biological or medical sciences. • have obtained a minimum gpa of 3.0 or equivalent. • have competence in reading, writing and speaking spanish. • a letter of intent showing a clear study goal. the department will evaluate applications received by october 30, 2002. courses will begin january of 2003. more information: secretaria académica facultad de ciencias antropológicas/uady tel. 99-25-45-23 or write to dr. v. tiesier at vtiesler@yahoo.com http:www.uady.mx/sitios/antropol/index.html information supplied by dr. andrea cucina cal variants in the skeleton and their quantitative treatment for populations comparisons. homo 24: 204-233. sjøvold t. 1977. non-metrical divergence between skeletal populations: the theoretical foundation and biological importance of c.a.b. smith’s mean measure of divergence. ossa vol. 4 (supplement 1). smith bh, garn sm, cole pe. 1982. problems of sampling and inference in the study of fluctuating dental asymmetry. am j phys anthropol 58:281-289. smith p. 1976. evolutionary changes in the deciduous dentition of near eastern populations. bull group int rech sci stomatol 19:187–198. smith p. 1978. evolutionary changes in the deciduous dentition of near east populations. j hum evol 7: 401–408. tocheri mw, molto je. in press. aging fetal and juvenile skeletons from roman period egypt using basiocciput osteometrics. int j osteoarch. townsend gc. 1981. fluctuating asymmetry in the deciduous dentition of australian aboriginals. j dent res 60:1849-1857. townsend gc, brown t. 1980. dental asymmetry in australian aboriginals. hum biol 52:661-673. townsend gc, brown t. 1981. the carabelli trait in australian aboriginal dentition. arch oral biol 26: 809-814. trinkaus e. 1978. bilateral asymmetry of human skeletal nonmetric traits. am j phys anthropol 49:315-318. turner ii cg. 1985. expression count: a method for calculating morphological dental trait frequencies by using adjustable weighting coefficients with standard ranked scales. am j phys anthropol 68: 263-267. turner ii cg, scott gr. 1977. dentition of easter islanders. in: dahlberg aa, graber tm, editors. orofacial growth and development. the hague: mouton, p 229-249. turner ii cg, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: ma kelley, cs larsen, editors. advances in dental anthropology. new york: wiley-liss, p 13–32. 18 dental anthropology 2018 │ volume 31 │ issue 02 deciduous molar morphology from the neolithic caves of the meuse river basin, belgium frank l’engle williams 1* , rebecca l. george 2 , and caroline polet 3 1 department of anthropology, georgia state university, atlanta, ga 30303 usa 2 department of anthropology, university of nevada, reno, nv 89557 usa 3 directorate earth & history of life, royal belgian institute of natural sciences, 1000 brussels, belgium there are nearly 200 karstic caves of the meuse river basin of belgium that preserve collective burials dating to the late neolithic (semal et al., 1999; toussaint et al., 2001; toussaint, 2007; polet, 2011). since habitation sites are rare, these funerary caves and rockshelters provide the principal source of information about these prehistoric farmers of the late neolithic and the transition to the bronze age (toussaint, 2007; polet, 2011). the mortuary practices of neolithic peoples from this region vary considerably. some tombs contain a single burial, whereas others include two or more individuals (toussaint et al., 2001), although the great majority are collective burials (polet, 2011). the bones of multiple individuals are comingled in some caves. burials are rarely found in full articulation, except in cases where single individuals are interred (toussaint, 2007). at some caves, there is regrouping of bones into elements, such as circles of crania and bundles of long bones (toussaint, 2007). some individuals are completely macerated as evidenced by flint tool use (polet, 2011), whereas others are cremated remains (toussaint, 2007). at bois madame, a site in the burnot valley (figure 1), it is unclear whether individuals were buried as the bones are found in an unordered manner (dumbruch, 2003). there may be several explanations to account for commingling within the collective burials, including the actions of burrowing and scavenging animals, geological or hydrological effects, recent human activity from grave robbers and cave explorers, or the intentional manipulation of the remains by those who deposited the deceased. intentional manipulation may have several motivations, including burial rites, secondary reburial and creating space for additional bodies (dumbruch, 2003; toussaint, 2007). about 40% of nearly 600 individuals excavated from 34 sites along the meuse river system are subadults (toussaint et al., 2001; toussaint, 2007). at bois madame nearly a third of the individuals (33%) are identified as children (dumbruch, 2003, 2007). more recent excavations with improved techniques are able to capture additional subadult remains, raising the proportion of children to 50% (toussaint, 2007). four cave sites contain numerous subadult remains, including hastière caverne m, sclaigneaux, bois madame and maurenne caverne de la cave, abstract the karstic caves of the meuse river basin in belgium preserve nearly 200 collective burials dating to the late neolithic period. among these, the cave burials of hastière caverne m, sclaigneaux, bois madame and maurenne caverne de la cave are represented by numerous individuals and radiocarbon dated to circa 4,635 to 3,830 years b.p. dental casts from mandibular and maxillary deciduous molars are scored using multiple methods to provide a regional overview of the prevalence and expression of deciduous molar crown traits, and to compare frequencies between cave burial sites with a focus on temporal differentiation. carabelli’s trait varies from a small pit to a full cusp, the largest of which are found at hastière caverne m. the hypoconulid ranges from moderately large to very large. a metaconulid is absent or small. although the results are contingent on idiosyncratic preservation, differences in the frequencies of expression of carabelli’s trait, a pronounced hypoconulid, and the presence of a metaconule and protostylid separate the earlier cave burial at hastière caverne m from the final/late neolithic sites of sclaigneaux and bois madame. *correspondence to: frank l’engle williams, phd department of anthropology georgia state university atlanta, ga 30303 usa frankwilliams@gsu.edu keywords: hastière caverne m; sclaigneaux; bois madame; maurenne caverne de la cave 19 dental anthropology 2018 │ volume 31 │ issue 02 radiocarbon dated to circa 4,635 to 3,830 years b.p. two of the four burials are from hastière rockshelter and include hastière caverne m and maurenne caverne de la cave (see figure 1). hastière caverne m has been radiocarbon dated to 4,345 ± 60 (ams oxa-6558; bronk-ramsey et al., 2002) and can be considered early/late neolithic. both sclaigneaux and bois madame can be considered final/late neolithic. the collective burial at sclaigneaux cave is dated to 4,155 ± 35 (paepe, 2007). bois madame is one of the latest sites in the sample, and the two dates obtained, 4,075 ± 38 (ams oxa 10831) and 3,910 ± 40 (ams oxa 10830), suggest the cave was in use during a relatively narrow time frame (dumbruch, 2003, 2007; toussaint, 2007). maurenne caverne de la cave from the hastière rockshelter is associated with four dates spanning ~800 years, including 4,635 ± 45 (ams oxa-9025), which is considered middle neolithic (toussaint, 2007) 4,160 ± 45 (ams oxa-9026), 3,950 ± 70 (lv-1483) and 3,830 ± 90 (lv-1482), all of which are final/late neolithic (bronk-ramsey et al., 2002; toussaint, 2007). since maurenne caverne de la cave includes such a wide range of radiocarbon dates, it cannot necessarily be considered “early” or “final” late neolithic. given the disparate funerary contexts that exist at neolithic belgian sites, the number of deciduous molars, and the high heritability of dental morphology (turner et al., 1991; scott and irish, 1997, 2017; irish, 2006; pilloud and larsen, 2011; paul and stojanowski, 2015, 2017; pilloud et al., 2016; scott et al., 2018), it is possible that differences in dental remains from each cave burial will parallel the chronological distinctions between sites (bronk-ramsey et al., 2002; paepe, 2007; toussaint, 2007). previous studies of the osteological remains have concentrated on dental microwear, isotopic signatures, stature estimation, pathological conditions, and funerary ritual (semal et al., 1999; garcía-martin, 2000; orban et al., 2000; toussaint et al., 2001; toussaint, 2007; polet, 2011). the expression of nonmetric deciduous dental traits from these cave burials has not been previously explored. the aim of the study is to provide a regional review of the incidence and expression of crown traits on the maxillary and mandibular deciduous molars, and to examine the frequencies of traits across cave burials with respect to temporal variation. on the basis of chronology, we expect the early/late neolithic site of hastière caverne m to be distinct from the final/late neolithic sites of sclaigneaux and bois madame. we anticipate maurenne caverne de la cave to present the most variation in dental morphology given its relatively broad time frame. ecogeography may also explain the results; the two cave burials from hastière rockshelter (hastière carverne m and maurenne caverne de la cave) may resemble each other and differ from sclaigneaux and bois madame (figure 1). materials deciduous molars were examined from hastière caverne m, sclaigneaux, bois madame and maurenne caverne de la cave for a total of 27 individuals (table 1). these gnathic remains are isolated such that each fragmentary molar and adjoining alveolus can be considered the sole remains from a given individual. although there are hundreds of isolated teeth, only in situ deciduous molars were considered. the stages (1-8) created by smith (1983, 1984) were used to characterize the wear on the deciduous molars (tables 2-5). figure 1. map of belgium shows the location of hastière rockshelter (hastière caverne m and maurenne caverne de la cave), bois madame and sclaigneaux. sclaigneaux is approximately 35 km northeast whereas bois madame is circa 15 km north of hastière rockshelter (drawing: adia ©). cave burial maxillae mandibles individuals hastière caverne m 3 2 5 sclaigneaux 8 1 9 bois madame 2 4 6 maurenne caverne de la cave 5 2 7 total 18 9 27 table 1. neolithic samples 20 dental anthropology 2018 │ volume 31 │ issue 02 identifier preservation dental wear (smith, 1984) hastière 38 nearly complete maxilla extending from the left unerupted crown of m1 to the empty m1 crypt on the right dm1 = stage 4; dm2 = stage 3 hastière 381 right maxillary alveolar fragment with dm1 and dm2 dm1 = stage 4; dm2 = stage 3 hastière 39 small maxillary alveolar fragment with dm1 and dm2 dm1 = stage 3; dm2 = stage 2 hastière 18 mandibular corpus extending from the left ramus base to the right dm1; only the left dm1 and dm2 are preserved dm1 and dm2 = stage 2 hastière 19 partial mandibular corpus extending from the left dm2 to the right damaged dm1 dm2 = stage 3 table 2. preservation and wear at hastière caverne m, an early/late neolithic cave burial identifier preservation dental wear (smith, 1984) sclaigneaux 115 relatively complete lower maxilla and dental arcade holding dm1 and dm2 on both sides dm1 = stage 5; dm2 = stage 4 sclaigneaux 116 relatively complete lower maxilla with dm1 and dm2 preserved on both sides dm1 and dm2 = stage 3 sclaigneaux 117 left maxillary fragment with dm1 and dm2 dm1 and dm2 = stage 3 sclaigneaux 118 left maxillary fragment, preserving dm2 and m1 dm2 = stage 5 sclaigneaux 119 left maxillary fragment and palate, preserving dm1, dm2 and m1 dm1 = stage 6; dm2 = stage 4 sclaigneaux 122 left maxillary fragment with the deciduous molars preserved; dm1 is slightly chipped dm1 = stage 7; dm2 = stage 4 sclaigneaux 124 small right maxillary fragment holding dm1, dm2 and m1 dm1 = stage 5; dm2 = stage 3 sclaigneaux 125 well-preserved right maxilla, with dm1 and dm2 dm1 = stage 5; dm2 = stage 4 sclaigneaux 82 small left corpus fragment holding dm1 and dm2 dm1 = stage 5; dm2 = stage 4 table 3. preservation and wear at sclaigneaux, a final/late neolithic cave burial identifier preservation dental wear (smith, 1984) bm mx 26 left fragmentary maxilla, preserving dm1 and dm2 dm1 and dm2 = stage 4 bm mx 27 left partial maxilla including most of the palate and alveolus, along with dm1, dm2 and m1 dm1 = stage 5; dm2 = stage 4 bm md 27 right mandibular corpus fragment with a partial ramus including dm1, dm2 and m1 dm1 = stage 5; dm2 = stage 4 bm md 28 right mandibular fragment with a complete ramus, and dm1 and dm2 dm1 = stage 5; dm2 = stage 4 bm md 32 left corpus and ascending ramus holding dm2 and m1 dm2 = stage 4 bm md 37 right corpus fragment with dm1 and dm2 dm1 = stage 4; dm2 = stage 3 table 4. preservation and wear at bois madame, a final/late neolithic cave burial table 5. preservation and wear at maurenne caverne de la cave, a cave burial with one middle and three final/late neolithic dates identifier preservation dental wear (smith, 1984) maurenne 22 right maxillary fragment holding dm1, dm2 and the unerupted crown of m1 dm1 = stage 3; dm2 = stage 2 maurenne 23 right maxillary fragment from the mesial margin of the m1 crypt to di1 dm2 = stage 7; dm2 = stage 4 maurenne 24 right maxillary fragment extending from the crypt of the m1 crown to di1 with only dm1 (obscured by matrix) and dm2 dm2 = stage 2 maurenne 25 maxillary alveolus extending from a fully formed m2 crown to the canine crypt, with dm1, dm2 and m1 dm1 = stage 6; dm2 = stage 4 maurenne 26 maxillary alveolus, from the unerupted crown of m1 to di1, preserving dm1 and dm2 dm1 = stage 4; dm2 = stage 2 maurenne 82 nearly complete mandible holding dm1 and dm2 on both sides dm1 = stage 4; dm2 = stage 3 maurenne 85 corpus fragment extending from the base of the left ascending ramus to right dm1 crypt holding the left dm1, dm2 and m1 dm1 and dm2 = stage 4 21 dental anthropology 2018 │ volume 31 │ issue 02 methods dental impressions were created by the first author using a thin layer of polyvinylsiloxane (president jet plus regular body, coltène-whaledent) applied to the occlusal surface of in situ molars curated at the royal belgian institute of natural sciences. dental casts were created at georgia state university using centrifuged epoxy resin and hardener (beuhler), which was poured on the dental molds nestled within putty crucibles affixed beforehand with hardener (beuhler). the casts dried for 24 hours before extraction. dental casts were scored by the second author using hanihara (1961) and supplemented with scores for the hypoconulid (cusp 5) on dm2 and the metaconule (cusp 5) on dm2 from the asudas (turner et al., 1991; scott and irish, 2017), following paul and stojanowski (2015). the maxillary deciduous molars were scored for crown pattern of dm1 and dm2, carabelli’s trait on dm2, and the presence of a metaconule (cusp 5) on dm2. for the mandibular deciduous molars, only dm2 is considered following hanihara (1961) and the traits scored included the protostylid, hypoconulid (cusp 5), metaconulid (cusp 7), the central ridge of the metaconid (crm), and the distal trigonid crest (dtc). to validate the scores, photographs of the original material were consulted. results maxillary traits crown pattern for dm1 is noted in two individuals and varies considerably (table 6). specifically, at sclaigneaux, one individual exhibits a large protocone and paracone, and is classified as a score of 2. in contrast, an individual from maurenne caverne de la cave presents all four cusps but the hypocone and metacone are relatively modest in size corresponding to a score of 4(hanihara, 1961). the crown pattern for dm2 is uniformly classified as a score of 4 (hanihara, 1961). carabelli’s trait varies from a small pit in some individuals from sclaigneaux to a large independent cusp on the dm2 of hastière caverne m 39 (figure 2). it is present at all sites except bois madame. a metacon neolithic time period site id no. crown pattern dm1 crown pattern dm2 carabelli's trait dm2 metaconule (cusp 5) dm2 early/late hastière 38 4 5 0 hastière 381 4 hastière 39 4 7 1 final/late sclaigneaux 124 2 4 1 0 sclaigneaux 115 4 1 sclaigneaux 122 4 sclaigneaux 118 4 sclaigneaux 117 4 6 0 sclaigneaux 116 4 3 0 sclaigneaux 119 4 sclaigneaux 125 4 1 0 bois madame 26 4 bois madame 27 4 middle and final/late maurenne 24 4 2 0 maurenne 25 4 maurenne 23 4 maurenne 22 44 5 0 maurenne 26 4 4 table 6. maxillary deciduous molar traits figure 2. the only metaconule observed is a small cuspule on the right dm2 of hastèire caverne m 39 (a); this individual also exhibits a prominent carabelli’s cusp (b). scale bar = 1 cm. 22 dental anthropology 2018 │ volume 31 │ issue 02 ule is expressed only on hastière caverne m 39 (figure 2) and is absent at sclaigneaux and maurenne caverne de la cave. in the bois madame sample, it could not be observed (see table 6). mandibular traits a protostylid is present only on the dm2 of a single individual from hastière caverne m (figure 3). the metaconulid expression varies from a larger feature in sclaigneaux (hanihara score 3) and maurenne caverne de la cave (hanihara score 2) to its absence or low expression at hastière caverne m and bois madame (table 7). a central ridge of the metaconid (crm), or cusp 7, is noted at all cave burials except bois madame, and a distal trigonid crest (dtc) is absent at hastière caverne m and maurenne caverne de la cave, but present at bois madame (figure 4). where it could be examined, the hypoconulid (cusp 5) was scored as either prominent (asudas grade 5) such as at hastière caverne m and sclaigneaux, or large (asudas grade 4) as at maurenne caverne de la cave, or both as is the case at bois madame (figure 5). figure 3. the expression of a protostylid (white arrow) is visible on the left dm2 of hastière caverne m 19. scale bar = 1 cm. neolithic time period site id no. protostylid dm2 metaconulid (cusp 7) dm2 crm dm2 dtc dm2 hypoconulid (cusp 5) dm2 early/late hastière 19 1 1 0 hastière 18 0 2 0 5+ final/late sclaigneaux 82 3 2 5 bois madame 37 0 5 bois madame 32 1 bois madame 28 4 bois madame 27 1 middle and final/late maurenne 82 2 2 0 4 maurenne 85 0 table 7. mandibular deciduous molar traits figure 4. a small metaconulid (a) and a large hypoconulid (b) can be observed on the right dm2 of maurenne 82. scale bar = 1 cm. figure 5. the largest and most distinctive hypoconulid (cusp 5) is visible on the right dm2 of hastière caverne m 18, identified by a white arrow. scale bar = 1 cm. 23 dental anthropology 2018 │ volume 31 │ issue 02 frequencies of traits per neolithic cave site for dm2, the crown pattern of hastière caverne m did not differ from the other collective burials. however, hastière caverne m was partially distinct from the other sites for carabelli’s trait, which was strongly expressed where it was demonstrably visible (table 8). furthermore, there is more variation in the expression of a metaconule on dm2 at hastière caverne m, and this is the only site known to express a protostylid (figure 3). hastière caverne m also differs in the expression of the metaconulid (figure 4) when compared to the ones from the final/late collective burial of sclaigneaux, and to a lesser extent maurenne caverne de la cave (see table 8). the final/late neolithic cave burial of bois madame differs from hastière caverne m in exhibiting a distal trigonid crest (dtc), albeit of a low expression. bois madame is also distinct from the early/late neolithic site of hastière caverne m for exhibiting greater variation in the expression of the hypoconulid (cusp 5) on dm2 (see table 8). discussion the morphology of the deciduous teeth has been examined in studies of modern humans (hanihara, 1961; edgar and lease, 2007; pilloud and larsen, 2011), pleistocene homo (smith and tillier, 1989; bailey and hublin, 2006; martinón-torres et al., 2012; hershkovitz et al., 2016; zubova et al., 2016) and the african apes (hardin and legge, 2013). because primary crown formation time is shorter, environmental pressures are reduced, resulting in a tendency of the deciduous dentition to preserve the ancestral condition more often than permanent successors (paul and stojanowski, 2017; scott et al., 2018). indeed, deciduous teeth have grade site n trait 0 1 2 3 4 45 6 7 sclaigneauxb 1 crown pattern (dm1) 1.00 maurennec 1 1.00 hastièrea 3 crown pattern (dm2) 1.00 sclaigneauxb 8 1.00 bois madameb 2 1.00 maurennec 5 1.00 hastièrea 2 carabelli's (dm2) 0.50 0.50 sclaigneauxb 5 0.60 0.20 0.20 maurennec 3 0.33 0.33 0.33 hastièrea 2 metaconule cusp 5 (dm2) 0.50 0.50 sclaigneauxb 4 1.00 maurennec 2 1.00 hastièrea 1 protostylid (dm2) 1.00 hastièrea 2 metaconulid cusp 7 (dm2) 0.50 0.50 sclaigneauxb 1 1.00 bois madameb 2 0.50 0.50 maurennec 2 0.50 0.50 hastièrea 1 crm (dm2) 1.00 sclaigneauxb 1 1.00 maurennec 1 1.00 hastièrea 2 dtc (dm2) 1.00 bois madameb 1 1.00 maurennec 1 1.00 hastièrea 1 hypoconulid cusp 5 (dm2) 1.00 sclaigneauxb 1 1.00 bois madameb 2 0.50 0.50 maurennec 1 1.00 table 8. pooled frequencies a early/late neolithic; b final/late neolithic; c middle and final/late neolithic 24 dental anthropology 2018 │ volume 31 │ issue 02 been shown to exhibit greater efficacy in indicating relatedness than the permanent dentition (kitagawa et al., 1995; paul and stojanowski, 2017), and are better at distinguishing groups than metric traits (sciulli, 1977). although deciduous and permanent teeth may not differ in proxies of environmental stability, such as fluctuating asymmetry (guatellisteinberg et al., 2006), the primary dentition has fewer cases of agenesis or supernumerary teeth compared to adult successors (scott et al., 2018). the entire primary molar row (including the deciduous and permanent teeth) may reflect an underlying unified mechanism of expression. at the same time, the deciduous dentition appears to be governed by partially distinct genetic and developmental processes than the permanent teeth, such that the presence of a protostylid on dm2 (see figure 4) does not necessarily imply that this trait will appear on any of the permanent molars (scott et al., 2018). furthermore, carabelli’s trait tends to be more prevalent and more strongly expressed in dm2 compared to m1 (kaul and prakash, 1981; bermúdez de castro, 1989; edgar and lease, 2007; scott et al., 2018). to the degree to which carabelli’s trait and the protostylid are informative about biological relationships, it would suggest that hastière caverne m does indeed differ from the other cave burials. in a study of early neolithic çatalhöyük, pilloud (2009) found that for the deciduous dentition, carabelli’s trait of dm2 and the presence of a protostylid on dm2 significantly separated groups, and this appears to be true among the late neolithic cave burials from belgium. prehistoric deciduous teeth have been scarcely examined given a historical preference for the permanent dentition (scott et al., 2018). an informative study by scuilli (1977) described the deciduous dental morphology of prehistoric amerindian hunter/ gatherer/fishers and early mississippian cultivators of the ohio valley. the crown form on dm1 in the prehistoric amerindian remains is most frequently four cusps (paracone, protocone, metacone and hypocone) like at maurenne caverne de la cave (see table 6). the crown form on dm1 of an individual from sclaigneaux including only the two mesial cusps was rarely found in 58 individuals from 12 sites (sciulli, 1997). the dm2 presents four cusps in both prehistoric amerindian and neolithic belgian cave sites (sciulli, 1977; see table 8). however, carabelli’s trait is extremely rare among prehistoric amerindians, whereas it is present and expressed strongly in three of the four neolithic cave sites from belgium, only being absent from bois madame (see table 6). in comparison to sciulli (1977) a metaconulid (cusp 7) on dm2 was found at lower frequencies compared to the results from this study, although the constraints of the small sample sizes must be taken into consideration (see table 8). each of the neolithic cave burials exhibits a hypoconulid (cusp 5) which compares to 97% of the prehistoric amerindians who exhibit five or more cusps on dm2 (sciulli, 1977). conclusions the deciduous molars from the neolithic caves of belgium present considerable variation in the expression of traits. crown pattern varies where it can be observed. carabelli’s trait is found at hastière caverne m, as well as the final/late neolithic cave site of sclaigneaux and at maurenne caverne de la cave, although its expression varies. the individuals preserving dm2 generally exhibit a large or very large hypoconulid (cusp 5). given the wide range of radiometric dates from maurenne caverne de la cave, it was expected to exhibit the greatest variability. like sclaigneaux, maurenne caverne de la cave does present substantial variation in the expression of carabelli’s cusp and in the metaconulid (cusp 7) compared to hastière caverne m. the resemblance of the two collective burials from hastière rockshelter (hastière caverne m and maurenne caverne de la cave) is not particularly strong although the number of individuals involved is severely constrained. we expected to observe differences between the early/late collective burial of hastière caverne m and the final/late neolithic sites of sclaigneaux and bois madame. hastière caverne m does exhibit the most pronounced expression of carabelli’s cusp on dm2, and this trait is found nearly universally in the sample (see figure 2). hastière caverne m also has the largest hypoconulid (see figure 5), and this cave burial is the only assemblage to express a protostylid on dm2 (see figure 3) and a metaconule on dm2 (see figure 2). since no other site presents these distinctions, it appears that the deciduous dental morphology of the early/late neolithic cave assemblage of hastière caverne m does indeed differ from the final/late neolithic collective burials of sclaigneaux and bois madame. population movement or displacement and/or secular changes may explain some of the differences in the frequencies of traits if the cave burials represent a single group of closely related peoples. alternatively, these populations may have had only a limited amount of regional gene flow during the late neolithic period. previous studies indicate that deciduous dental morphology approximates, to a greater extent than the secondary dentition, the ge25 dental anthropology 2018 │ volume 31 │ issue 02 netic relationships among individuals (kitagawa et al., 1995; paul and stojanowski, 2017). to the degree to which this is also true of these neolithic cave burials, it can be assumed the people represented at hastière caverne m were relatively isolated several centuries prior to a partial restructuring of the regional population associated with the bronze age. acknowledgments permission to examine the neolithic remains from belgium and to conduct this study of the deciduous dentition was kindly provided by patrick semal, chief of the scientific heritage service, royal belgian institute of natural sciences. we are indebted to laurence cammaert from the adia (association pour la diffusion de l'information archéologique) who created figure 1 which we utilize with permission. we are grateful to two anonymous reviewers who significantly improved the manuscript, and to attendees of the 2017 annual meeting of webig (western bioarchaeology group) for their helpful insights. funding for this research was awarded to flw by fulbright-belgium and the commission for educational exchange between the usa, belgium, and luxembourg. references bailey s.e., hublin j.-j. 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(2007). correlations between deciduous and permanent tooth morphology in a european american sample. american journal of physical anthropology, 133, 726–734. garcía-martin c. (2000). reconstitution du régime alimentaire par l’étude des micro-traces d’usure dentaire. ma thesis, université libre de bruxelles. guatelli-steinberg d., sciulli p.w., edgar h.j.h. (2006). dental fluctuating asymmetry in the gullah: tests of hypotheses regarding developmental stability in deciduous vs. permanent and male vs. female teeth. american journal of physical anthropology, 129, 427–434. hanihara k. (1961). criteria for classification of crown characters of the human deciduous dentition. journal of the anthropological society of nipon, 69, 27–45. hardin a.m., legge s.s. 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(2012). morphological description and comparison of the dental remains from atapuerca-sima de los huesos site (spain). journal of human evolution, 62, 7–58.bottom of form orban r., polet c., semal p., leguebe a. (2000). la stature des néolithiques mosans. bulletin de l'institut royal des sciences naturelles de belgique, série sciences de la terre, 70, 207–222. paepe m. de (2007). studie van de laat-neolithische menselijke resten uit een collectief graf te sclaigneaux (provincie namen, b.). ma thesis, universiteit gent. paul k.s., stojanowski c.w. (2015). performance analysis of deciduous morphology for detecting biological siblings. american journal of physical anthropology, 164, 97–116. paul k.s., stojanowski c.w. (2017). comparative performance of deciduous and permanent dental morphology in detecting biological relatives. american journal of physical anthropology, 157, 615–629. pilloud m.a. 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(1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in m. a. kelley & c. s. larsen (eds.), advances in dental anthropology (pp. 13–31). new york: wiley-liss. vanderveken s. (1997). etude anthropologique des sépultures néolithiques de maurenne et hastière (province de namur). ma thesis, université libre de bruxelles. zubova a.v., stepanov a.d., kuzmin y.v. (2016). comparative analysis of a stone age human tooth fragment from khaiyrgas cave on the middle lena (yakutia, russian federation). anthropological science, 124, 135–143. aguirre et al. 2006.2 39 dental anthropology is the area of study that integrates anthropology, dentistry, biology, paleontology and paleopathology in order to holistically investigate the human dentition, such as the anatomical, evolutionary, pathological, and cultural variations with regard to life conditions, culture, feeding patterns and past adaptation processes in human populations. the scope of study includes metric and non-metric dental traits, dental pathology and intentional plus occupational modifications of the teeth (scott and turner, 1997, 1998; alt et al., 1998; rodríguez, 1999; rodríguez and delgado, 2000; mayhall, 2000; rodríguez, 2004). one facet of dental anthropology is dental morphology. dental morphology is the discipline used to register, analyze, interpret and understand all aspects of dental crown and root morphology that can inform us about human groups, such as their cultural activities, biological conditions, and quality of life (rodríguez, 2004). from this perspective, teeth are informative indicators for the study of human populations, serving as markers and the bases for comparisons of genetic origin, allowing for the classification of human groups in taxonomic, phylogenetic and evolutionarily categories by means of their frequency, sexual dimorphism, bilateral symmetry and morphological characteristics (rodríguez, 1999; rodríguez, 2003a). this is possible because teeth commonly are preserved even in the extreme conditions in which skeletal remains are found. teeth are the organs that are best preserved because frequency and variability of five non-metric dental crown traits in the primary and permanent dentitions of a racially mixed population from cali, colombia luisa aguirre, diana castillo, diana solarte, and freddy moreno* oral and maxillofacial surgery research group (dental anthropology and forensic dentistry research line), school of dentistry school,university of valle, cali colombia *correspondence to: freddy moreno, dental morphology and dental anthropology, escuela de odontología . universidad del valle sede san fernando, calle 3a no. 36b-00 edificio 132, cali colombia. e-mail: freddyodont@hotmail.com abstract: the purpose of this study was to determine the prevalence and variability of five non-metric dental crown traits (carabelli cusp, protostylid, groove pattern, and cusps 6 and 7) in the deciduous (um2 and lm2) and permanent (um1 and lm1) teeth in children in the mixed-dentition, and to compare these frequencies with the literature. a descriptive study was conducted to characterize the dental morphology of young subjects in mixed dentition stages. the arizona state university dental anthropology system (asudas) and grine, sciulli, and hanihara methods were used as reference to compare the prevalence of dental traits in dental casts from 100 subjects from a colombian racially mixed population. the high prevalence of furrows and pits of the carabelli cusp, minor expressions of the protostylid (foramen cecum), and the low frequencies of cusps 5 and 6, plus the behavior of the expression of groove pattern collectively suggest that this group reflects influences by both the mongoloid and caucasoid dental complexes. correspondence of trait expression in both the primary and permanent dentition was also demonstrated (p < 0.05). some of the non-metric trait frequencies also exhibited sexual dimorphism. dental anthropology 2006;19(2):39-47. enamel is the hardest tissue of the human body, having the capacity to resist high temperatures and taphonomic processes (e.g., time, environment, ph, salinity, humidity, attack by trace elements) (rodríguez, 2004; moreno and moreno, 2005). consequently, teeth constitute a means of personal identification where other information may be unavailable, thus contributing to an unknown individual’s osteobiographical reconstruction through forensic means (krogman, 1986). also, in archeological and anthropological contexts, dental anthropology can help estimate a populations’ temporal position to clarify its history, origin, formation, contacts and displacements of current and past human groups (moreno and moreno, 2005; rodríguez, 2003a; turner et al., 1991). non-metric dental crown traits ( ndct) are phenotypic forms of the enamel that are inherited and controlled in their location, growth and orientation; they result from indirect processes of mineral secretion mediated by proteins the dental morphogenesis, and they are expressed and regulated by the human genome of each individual. these traits can be described as positive (cusps) or negative structures (pits, furrows 40 l. aguirre et al. and grooves) that have the potential to be present or absent in a specific place (frequency), in a different form or grade (variability), and in one or more members of a populational group. to date, there are more than 100 non-metric dental crown and root traits described in the human dentition (rodríguez, 2003a); in the present investigation, three traits were used that occur on the crown complex of primary second molars and permanent first molars. in the dental literature, ndct are described using a broad host of names, such as characters, variants, aspects, attributes, polymorphisms, anomalies, discrete traits, and epigenetic or phenotype expressions (rodríguez, 2003a,b; rodríguez, 2003). the study of ndct has demonstrated that the traits are of high taxonomic value; they can be used to estimate biological relationships among groups, allowing researchers to reconstruct and establish intergroup relationships for the comparative analysis of historical, cultural and biological development of primitive and modern human groups. ndct seem to seldom exhibit sexual dimorphism; statistical associations among traits seem to be low; and there is considerable geographic variation in trait frequencies. ndct are easily observed and recorded; they thus are useful for establishing population differences according to a group’s specific microevolutionary processes, which furnishes information about the displacements and contacts that have taken place (rodríguez, 2003a,b; rodríguez, 2003; tocheri, 2002). in colombia, dental anthropology research is primarily concerned with forensic applications and the dental pathological study of pre-hispanic populations. these interests are carried out by the physical anthropology laboratory of the national university of colombia, the biological anthropology research group giab, and the anthropology departament of cauca university. it is necessary to note that the few investigations in this part of the world that have characterized dental morphology have focused on pre-hispanic populations, plus a few current and modern populations. these latter studies have been limited to the permanent dentition. it is important to keep in mind that the complete primary dentition persists for only a short time; it begins at six months and finishes at two a half years, then it stays intact until about six years, and finally disappears about 12 years of age (clarke, 1998). in spite of this transience, research on the deciduous dentition provides an excellent model for studying variation of growth within an individual since, in both dental and anthropological contexts, the dentition constitutes a unique source of information about development (smith et al., 1997). in addition, investigators have studied the primary dentition in various human groups, finding interesting data on the intergroup variations of ndct. a pioneer in this field was k. hanihara (e.g., 1966, 1968), who established the mongoloid dental complex as it relates to the permanent and primary dentitions. other researchers, such as kitagawa et al. (1995) and kitagawa (2000), have shown that the morphology of primary teeth is efficient for the study of biological affinities among human populations, contributing to the understanding of human dental evolution. lease and sciulli (2005) concluded that the morphology of the primary dentition is useful for establishing the identity of children, for the biological discrimination of two or more human groups, and for establishing differences in development between the deciduous to the permanent dentition. the objective of the present study was to determine the frequency and variability, sexual dimorphism, and bilateral symmetry of five ndct, namely carabelli’s trait, the protostylid, molar groove pattern, and cusps 6 and 7, of the primary second molars (um2 and lm2) and the permanent first molars (um1 and lm1), which coexist in the mouth between about six years (± 24 months) and ten years of age (± 30 months) (schour, 1941; rodríguez, 2004). the goal, then, was to compare these frequencies in both dentitions, with the purpose of understanding the developmental behavior of these three features, the dominant ethnic influence, and the dental morphological characters of the sample. we hope that these findings will contribute to discussions of the usefulness of dental morphology as an anthropological tool, not only in the context of dentistry, but also that of forensic studies (edgar, 2005; moreno and moreno, 2005; moreno et al., 2004). materials and methods samples this is a descriptive cross-sectional study concerning the frequency and variability of five ndct in 100 children (50 male and 50 female) selected randomly from a single living population of a racially mixed group from cali, colombia (fig. 1). the children studied here were 6 to 12 years of age. in order to be included, the subjects had to met four criteria, namely (1) they had to have colombian parents and grandparents, (2) they had to be healthy dentally without any congenital anomaly, (3) they had to exhibit no severe attrition or abrasion, and (4) they had to possess upper and lower first permanent molars and primary second molars. morphological analysis standardization for the observation of the five ndct in the permanent dentition this study used the arizona state university dental anthropology system (asudas) (turner et al., 1991; turner et al., 1994). this system allows for finer discrimination than just the dichotomy of presence-absence of traits, it promotes reproducibility among observers, and it generates data that express the variability of expression of each ndct along with the potential extremes. for analysis of the deciduous dentition, this study used the asudas method for cusp 41nonmetrics of cali, colombia fig. 1. cali, colombia geographic localization 7, the hanihara method (1966) for the cusp 6, the grine method (1986) for the carabelli trait, and the sciulli method (1998) for the protostylid and molar groove pattern. these complementary methods, along with the grading systems, are described in the appendix. turner et al. (1991) described 29 ndct that can be applied in populational investigations based on their prevalence and variability. these authors suggest that this suite of ndct involves clear expressions of the genotype and that they are little-influenced by environmental factors when scored on key teeth as defined by the morphogenetic field concept (dahlberg, 1945). for the present study, carabelli trait, protostylid, molar groove pattern, and cusps 6 and 7 cusps are used. calibration the authors practiced the handling of arizona state university dental anthropology system (asudas) and the hanihara, grine and sciulli methods by making repeated series of observations and then comparing among observers to achieve consistency. repeated comparisons led to standardization of concepts among observers. we applied the kappa statistic (stata 6.0) to assess repeatability; analysis disclosed inter-observer agreement values of 82.3% and intra-observer 81.2%, following the method suggested by nichol and turner (1986). tooth impressions and study casts this investigation was endorsed by the human ethics committee of the university of the valley according to the ministry of health of the republic of colombia (1993) and the ethical principles for medical research involving human subjects indicated for the world medical association in the helsinki declaration (1964). after obtaining the signed written consent and the intraoral examination, dental impressions were taken from the subjects using sterile plastic small buckets (coe for id®) and alginate (hydrogum®). casts were immediately processed in dental stone (whipmix®) to prevent distortion. observation and statistical analysis with the obtained study casts, the best calibrated observer performed the analysis using a stereomicroscope (carl-zeiss®) at 10-power, evaluating three ndct: carabelli trait, protostylid and molar groove pattern in the primary and permanent dentitions. the resulting data were processed using the spss® software version 10. several statistical tests were applied (chi-square tests, univariate and bivariate comparisons, mann-whitney u) for each of the ndct. the conventional level of alpha = 0.05 was considered to be statistically significant. results the principal objective of this research was to observe the existing relationship of the ndct studied between primary and permanent dentitions. results were determined to be positive with regard to the carabelli trait and protostylid frequencies. the groove pattern did not exhibit a significant association between molars in the two dentitions. analysis of the expression of the ndct between girls and boys showed that there was no detectable sexual dimorphism in the primary or the permanent teeth for these three traits, but there was considerable bilateral symmetry of all three features in the primary and permanent dentitions (tables 2 and 3). in deciduous and permanent teeth, carabelli trait most commonly exhibited the fossa form on the cusp. viewed as a dichotomous trait, it is absent in this sample (figs. 2 and 3). the protostylid occurred as grade 1 (foramen cecum) in the majority of cases in both the primary and permanent teeth (fig. 4). expressions of the protostylid pit were far more common than the cusp form (tables 2 and 3). inspection of the molar groove patterns showed that the y and + pattern were common in both dentitions, although in primary teeth there was a higher frequency of the y configuration and a higher frequency of the + form in the permanent teeth (table 2; fig. 5). the frequency of cusp 6 and 7 was low in both 42 fig. 2. carabelli trait: cusp expression in primary second molar (um2) and permanent first molar (um1). fig. 3. carabelli trait: fossa expression in primary second molar (um2) and permanent first molar (um1). table 2. frequencies of nonmetric dental traits1 total frequency u test bilateral symmetry tooth trait (left side) males females p value left right um2 carabelli trait 15 16 14 0.951 15 16 um1 carabelli trait 42 42 42 0.952 42 40 lm2 protostylid 1 0 2 0.239 1 0 lm1 protostylid 4 4 4 0.407 4 5.1 lm2 groove pattern y 81 80 82 0.731 81 72 lm2 groove pattern + 17 16 18 0.731 17 26 lm2 groove pattern x 2 4 0 0.731 2 2 lm1 groove pattern y 41 54 28 0.009 41 39 lm1 groove pattern + 59 46 72 0.009 59 54 lm1 groove pattern x 0 0 0 0.009 0 7 lm2 cusp 6 12 16 8 0.025 12 8 lm2 cusp 7 24 28 20 0.103 24 20 lm1 cusp 6 4 3 5 0.320 4 4 lm1 cusp 7 19 22 16 0.084 19 17 1the mann-whitney u test assessed sexual dimorphism based on just left sides. l. aguirre et al. dentitions, although cusp 7 is more common than cusp 6 (table 2; figs. 6 and 7). discussion carabelli trait kieser (1984) observed a high frequency of this trait in both the deciduous and permanent teeth. joshi (1975) studied a hindu population and found that there is a relationship between the prevalence of the feature, bilateral symmetry expression and high prevalence in the groove and fossa forms on the tubercle and cusp forms. saunders and mayhall (1982) studied five ndct on the primary and permanent teeth of a sample of american whites, finding strong positive associations between traits in the two dentitions. k. hanihara (1954) carried out several of studies on the trait frequencies of ndct in primary and permanent dentitions of asian, polynesian and australians, contemporary and prehistoric. hanihara focused on the ndct that characterize the mongoloid complex (shovelshape, protostylid, deflecting wrinkle, cusps 6 and 7) and the carabelli trait. as for this last trait, hanihara (1976) determined that caucasoid populations can be distinguished from asian populations, predominantly in this last the groove and pit forms. 43 fig. 4. protostylid pit expression in primary second molar (lm2) and permanent first molar (lm1). fig. 5. groove pattern y5 on primar second molar (lm2) and +5 on permanent first molar (lm1). fig. 6. cusp 6 on primary second molar (lm2) and permanent first molar (lm1). fig. 7. cusp 7 on primary second molar (lm2) and permanent first molar (lm1). nonmetrics of cali, colombia studies from india (kannapan and swaminathan, 2001) and saudi arabia (salako and bello, 1998) show the relationship of the frequency, bilaterally and absence of sexual dimorphism between temporary and permanent teeth. pinkerton et al. (1999) observed carabelli trait in both dentitions in 245 pairs of monozygotic and dizygotic australian caucasoid twins, finding little influence of sexual dimorphism on the primary or permanent dentition. their findings showed that some traits (like carabelli) of the primary dentition exhibited considerable genetic control and, thus, little alteration by the environment. the frequency of the carabelli trait is highest in caucasians and lower in other populations, though american negroes show relatively high frequencies of this trait compared to japanese, ainu and pimas, and the cusp is practically absent in eskimos (hanihara, 1976). moreno et al. (2004) and moreno and moreno (2005) report the carabelli trait frequency to be 40.5%. in the present study, carabelli’s trait is sexually dimorphic; it is expressed bilaterally; and the furrow and pit forms predominate over the tubercle and cuspid forms in both the primary and permanent dentition, suggesting that there is ambivalence in the population discrimination of this trait. the association of the trait between the dentitions may suggest a strong genetic control for its expression (tables 4 and 5). protostylid the protostylid has been defined as an “american feature” due to the occurrence of high frequencies in the european, african and asian populations of the 44 l aguirre et al. americas, and to the particularly high prevalence of the foramen cecum in american populations (rodríguez, 1999, 2004). robbins (1998) indicated that the fossa or pit forms (foramen cecum) of the protostylid prevail over the cuspal form in the primary and permanent dentitions. hanihara (1976) found that cusp forms of the protostylid were found in low frequency in most populations, rarely occurring in modern human groups, notably asians. this led him to note that this trait is useful for differentiating the mongoloid dental complex of the caucasoid and negroid. in primary teeth, it is common to find the fossa form of the protostylid, but the trait rarely reaches the height or size of a cusp. in the deciduous dentition, the protostylid is frequently observed on the mandibular second molars. frequencies of this trait seem to be highest in eskimos and the pima, and relatively low in japanese and ainu. in caucasians and american whites, it was seldom observed (hanihara, 1966, 1976). moreno et al. (2004) and moreno and moreno (2005) found a frequency of this feature in permanent teeth of 1.5%, with a high frequency of the point p. the population observed in this study presents a retention of the amerindian dental complex, evidenced by the high frequency of the grade 1, which is the fossa or pit in the buccal developmental groove that separates the mesiobuccal and distobuccal cusps (tables 4 and 5). groove pattern this trait is defined by the basic arrangement of grooves and cusps of the occlusal surface of deciduous and permanent molars (hillson, 1996). smith et al. (1987) analyzed children from five ethnic groups, concluding that there are no significant differences between expressions of the groove pattern between the first permanent molar and the second primary molar, with the y pattern occurring most frequently. a study of children with caucasoid characteristics from india (kaul and prakash, 1981) reported the common occurrence of the pattern y in primary and permanent teeth, the same as in an eskimos from alaska (hasund and bang, 1985). this trait characterizes the occlusal surface of the low molars by means of a contact pattern of the cusps, that can be configured in the y, + or x forms. y is the ancestral pattern considered as present, while x and + configurations are reductions or absences (scott and turner, 1997), frequently observed in caucasoid groups. the temporary mandibular second low molars show a bigger tendency to the configuration y. in this study the behavior of the intercusp contact furrows was given by the y pattern or “ dryopithecus “ for the primary lower second molars and + or a “cross-like structure” for the permanent lower first molars; this can be due to that the primary dentition present a stronger genetic control, for what the dryopithecus pattern native of the last asian populations have conserved. in the case of the permanent first molars, it is assumed that the miscegenation processes mark a tendency toward the + pattern, which is a characteristic of the caucasoid populations. in both dentitions, bilateral symmetry is observed in trait expression, but sexual dimorphism is not discernible. in most publications, the groove pattern and the number cusp have been described together, for example y5 or +4, although the number of cusps varies independently of the groove pattern (mayhall, 2000). in the present sample, the y5 configuration was observed in the deciduous second low molar which is a characteristic of mongoloid and african populations. in the permanent first low molar prevailed +5 configuration, characteristic of caucasian and hybrid european groups (rodríguez, 2003) (tables 4 and 5). cusp 6 the sixth cusp is known as the tuberculum accessorium posteriore internum (mayhall, 2000). hanihara (1966, 1976) shows that this feature is an accessory cusp, and, when it appears, it is located between the distolingual and the distobuccal cusps of the primary and permanent mandibular molars. the incidence of this cusp, in primary and permanent dentitions, has been studied by several researchers, and it has been described as a racial characteristic of mongoloid populations. frequencies of cusp 6 also show a distinct contrast between populations. the expression of this trait occurs fairly commonly in japanese, ainu, and the pima. similar results are observed in the primary dentition (hanihara, 1976). in one study, the frequency of this characteristic was 5% (moreno et al., 2004; moreno and moreno, 2005) (tables 4 and 5). cusp 7 this is another accessory molar cusp, and it is located at the marginal border between the mesiolingual and distolingual cusps. it was originally described using the term tuberculum accessorium mediale internum, and many occurrences have been reported by several authors in the fossil and recent primates including man. among the permanent and deciduous mandibular molars of recent man, american blacks show the highest frequency, which distinguishes blacks from other populations. in primary mandibular second molars, the difference in frequencies of this character is much greater (hanihara, 1976). moreno et al. (2004) and moreno and moreno (2005) observed that the frequency of this characteristic to be 25% on permanent molars in a racially mixed population (tables 4 and 5). in overview, (1) the high frequency of the groove and fossa forms of carabelli trait, (2) the high frequency of the protostylid grade 1 (foramen cecum), (3) the low frequencies of cusps 5 and 6, and (4) the expression of the molar groove pattern and number cusp collectively 45 table 3. three nonmetric trait frequencies in the primary and permanent dentitions deciduous permanent trait grade percent grade percent carabelli trait 0 3 0 31 1 82 1 4 55 2 4 15 5 7 14 prot ostylid 0 6 0 19 1 93 1 76 2 1 2 7 5 groove pattern y 81 y 41 + 17 + 59 x 2 x 0 cusp 6 0 1 88 0 1 96 2 5 12 2 5 4 cusp 7 0 76 0 81 1 3 24 1 4 19 table 4. frequency of nonmetric dental traits in permanent dentition samples carabelli trait protostylid groove pattern cusp 6 cusp 7 japanesea 6.5 6.6 26.0 (+) 25.3 6.7 pimaa 6.9 19.4 26.6 8.2 eskimoa 13 28.6 20.1 (y) 50 20 caucasiana 39 0 59.5 (+) 5.2 5.1 american blacksa 16.3 0 49.0 (+) 6.5 46.3 sinodontyb 32.1 34.7 10.9 (y) 47.8 9.8 sundadontyb 30.6 30 19.6 (y) 35.5 7.4 north american indianb 35.6 41.9 8.1 (+) 49.2 10.2 south american indiansb 41.9 29.8 9 (+) 55.8 9.6 thailandersc 26.6 20.4 71.8 (y); 25.6 (+) 17.1 2.4 american caucasoidd 45 0 84.1 (+) 5.2 5.1 colombian living indians 20 90 0 60 0 80 0 80 páeces (colombian indians)e 0.6 0.2 38 guambianos (colombian indians)e 0.2 0.1 emberá (colombian indians)e 60 20 obando pre-hispanicf 50 10 51.6 (y) 31 (+) 38.9 bogotá racially mixedg 28 4 cali racially mixedh 40.5 1.5 5.0 25.0 present study 50.0 4.0 41 (y) 59 (+) 4.0 19.0 ahanihara (1976, 1992), bturner (1984, 1990), cmanabe et al. (1997), drodríguez jv (1999, 2003), eleón and riaño(1997), frodríguez (2002), gherrera and osorno (1994); gmoreno et al. (2005). nonmetrics of cali, colombia suggest that the sample has received influence of the mongoloid and caucasoid dental complexes. this inference agrees with the studies of moreno et al. (2004), moreno and moreno (2005), león and riaño (1997), herrera and osorno (1994), turner (1984, 1990), sciulli (1998) and hanihara (1966, 1968) who affirm that all indigenous american groups exhibited a sinodont pattern of dental morphology (i.e., mongoloid dental complex subdivision of ne asia). it is supposed that this pattern has persisted since the original immigrants from asia peopled the americas by way of beringia. subsequently, the colombian historical development is such that the dental morphology of the current populations is the reflection of hybridization among mongoloid (pre-hispanic indigenous), caucasoid (spanish conquerors) and african (african slave) ethnic groups. as such, the sample observed in this study can be considered a hybrid group composed primarily from 46 table 5. percentages of nonmetric dental traits in the primary dentition sample carabelli trait protostylid groove pattern cusp 6 cusp 7 japanesea 11.9 47.7 36.9 73.7 eskimoa 13 28.6 37.7 79.4 caucasiana 35.7 14.5 7.3 40.7 american negroesa 11.8 19.1 12 46.8 modern japanb 11.5 53.8 33.3 87.0 pimac 5.1 80.8 88.7 (y) 36.8 70.8 hindusd 66.1 saudi arabiae 58.7 present study 15.0 1.0 81.0 (y); 17.0 (+) 12.0 24.0 ahanihara (1976), bkitagawa (2000), ctochieri (2002), djoshi (1975) and esalako and bello (1998) l. aguirre et al. mongoloid and caucasoid complexes (tables 4 and 5). conclusions the data presented here suggest, based on the ndct studied, that dm2 is more conservative in form than the permanent m1. the morphological similarities between the two teeth are well established with regard to the frequencies of carabelli trait, protostylid, molar cusp pattern, and cusps 6 and 7. there is correspondence in the expression of the carabelli trait and the protostylid between the primary and permanent dentitions, which implies a strong genetic control in its frequency and variability. in the case of the molar groove pattern, more investigations should be carried out on other colombian groups with increased sample sizes to better analyze the behavior of this feature among the two dentitions. sexual dimorphism does not exist and bilateral symmetry is observed in the expression of the five ndct studied in th deciduous and permanent dentitions. the data presented in this research indicate, based on the ndct studied, that dm2 is more conservative in form than m1. according to the frequency and variability of the ndct studied, it is indicated that the dental morphology of the sample constitutes a mix of the mongoloid and caucasoid dental complexes, which is reflected in the intermediate expressions of carabelli trait. the high frequency of the the pit form (grade 1) of the protostylid suggests that it is a genetic conservation of the amerindian dental complex as a result of the historical processes of peopling, distribution and establishment of the prehispanic human groups and admixture after the arrival of the europeans to the new world. the high expression of cusp 7 in grades 1 and 2 suggests an influence of the negroid dental complex. studies should be carried out on the frequency and variability of other ndct to increase interpopulation information and better characterize the dental morphology, not just of mixed populations with caucasian characteristics, but also of the afro-american and indigenous communities of the region, in order to better understand how information from the teeth inform us about the micro-evolutionary aspects, displacements, contacts, isolations and historical process on the colombian population. acknowledgments the authors would like to express their thanks to professors of the dental school research department of valle for their valuable help in this study. literature cited alt kw, rosing fw, teschler-nicola m. 1998. dental anthropology: fundamentals, limits, and prospects. new york: springer-verlag. clarke j. 1998. anthropology, human evolution, and hominid evolution. uic oral sciences osci 590 dental oral biology and the department of orthodontics, uic college of dentistry: http://www.uic.edu/ classes/orla/orla312 dahlberg aa. 1945. the changing dentition of man. j amer dent assoc 32: 676-680. edgar hj. 2005. prediction of race using characteristics of dental morphology. j forensic sci 50:269-273. grine fe. 1986. anthropological aspects of the deciduous teeth of african blacks. in: singer l, lundy jk, editors. variation, culture, and evolution in african populations. johanessburg: witwatersrand university press, p 47-83. hanihara, k. 1966. mongoloid dental complex in the deciduous dentition. j anthrop soc nippon 74:9-20. hanihara k. 1968. mongoloid dental complex in the permanent dentition. proceedings of the viiith international symposium of anthropological and ethnological sciences. tokyo: science council of japan; september 3-10, p 298-300. hanihara k. 1976. non-metric tooth crown characters: in statistical and comparative studies of the australian aboriginal dentition. bulletin no.11. tokyo: the university museum of the university of tokyo. 47nonmetrics of cali, colombia hanihara t. 1992. dental and cranial affinities among populations of east asia and the pacific. am j phys anthropol 88:163-182. hasund a, bang g. 1985. morphologic characteristics of the alaskan eskimo dentition. iv. cusp number and groove patterns of mandibular molars. am j phys anthropol 67: 65-69. herrera el, osorno m. 1994. cephalometric analysis and dental characterization of caucasoid habitants of bogotá. orthodontic postgraduate dissertation. bogotá: national university of colombia, dentistry school [in spanish]. hillson s. 1996. dental anthropology. cambridge: cambridge university press. joshi mr. 1975. carabelli’s trait on maxillary second deciduous molars and first permanent molars in hindus. arch oral biol 20:699-700. kannapan jg, 2001. swaminathan s. a study on a dental morphological variation. tubercle of carabelli. indian j dent res 12:145-149. kaul v, prakash s. 1981. morphological features of jat dentition. am j phys anthropol 54:123-127. kieser ja. 1984. an analysis of the carabelli trait in the mixed deciduous and permanent human dentition. arch oral biol 29:403-406. kitagawa y. 2000. nonmetric morphological characters of deciduous teeth in japan: diachronic evidence of the past 4000 years. int j osteoarchaeol 10:242-253. kitagawa y, manabe y, rokutanda a. 1995. deciduous dental morphology of the prehistoric jomon people of japan: comparison of nonmetric characters. am j phys anthropol 97:101-111. kitagawa y. 2000. nonmetric morphological characters of deciduous teeth in japan: diachronic evidence of the past 4000 years. int j osteoarchaeol 10:242-253. krogman wm, iscan my. 1986. the human skeleton in forensic medicine, 2nd ed. springfield: charles c. thomas publisher, p 531-534. lease lr, sciulli pw. 2005. brief communication: discrimination between european-american and african-american children based deciduous dental metrics and morphology. am j phys anthropol 126:56-60. león cf, riaño c. 1997. frequency of eight dental morphologic characteristics in pre-hispanic population of colombia compared with american, european and asian indigenous populations. orthodontic postgraduate dissertation. bogotá: research center and dentistry studies, military university nueva granada [in spanish]. mayhall jt. 2000. dental morphology: techniques and strategies. in: katzenberg ma, saunders sr, editors. biological anthropology of the human skeleton. new york: wiley-liss, p 103-134. manabe y, ito r, kitagawa y, oyamada j, rokutanda a, nagamoto s, kobayashi s, kato k. 1997. nonmetric tooth crown traits of the thal, aka and yao tribes of northern thailand. arch oral biol 42:283-291. ministry of health of the republic of colombia. 1993. article 11 de la resolution 008430 de octuber 4. scientific, technical, and administrative norms for health research [in spanish]. http://www. minproteccionsocial.gov.co/msecontent/images/ news/docnewsno267711.pdf moreno f, moreno sm, díaz ca, bustos ea, and rodríguez jv. 2004. prevalence and variability of eight non-metric dental traits in students of cali, colombia. col med 35 (supl 1):17-23 [in spanish]. http://colombiamedica.univalle.edu.co/ vol35no3supl/pdf/rasgos.pdf moreno sm, moreno f. 2002. dental anthropology: a valuable tool with forensic utility. revista estomatología 10:29-42 [in spanish]. moreno sm, moreno f. 2005. eight non-metric dental traits in live racially mixed population from cali, colombia. int j dent anthropol 6:14-25. nichol cr, turner ii cg. 1986. intra and inter-observer concordance in classifying dental morphology. am j phys anthropol 69:299-315. pinkerton s, townsend gc, richards ly, schwerdt w, dempsey p. 1999. expression of carabelli trait in both dentitions of australian twins. perspec hum biol 4:19-28. robbins gm. 1998. dental discrete traits and biocultural anthropology in gujarat, india. university of oregon anthropology department. http://gladstone. uoregon.edu/~grobbins/project.html rodríguez cd, delgado me. 2000. dental anthropology: a brief definition. int j dental anthropol 1:2-4. http://www.ijda.syllabapress.com 48 tooth, trait code grade reference primary upper second molar, carabelli’s trait um2 0. absent 1. u or y-shaped depression 2. two parallel furrows 3. small cusp 4. free cusp grine (1986) permanent first upper molar, carabelli’s trait um1 0. smooth surface 1. groove present 2. pit present 3. small y-shaped depression 4. large y-shaped depression 5. small cusp 6. medium cusp 7. free cusp asudas turner et al. (1991) primary second mandibular molar, protostylid lm2 0. absent 1. pit or furrow 2. cuspid sciulli (1998) permanent first lower molar, protostylid lm1 0. smooth surface 1. pit present 2. buccal groove curve distal 3. faint groove extending mesial from the bucal groove 4. groove more pronounced 5. groove stronger 6. groove extend across the buccal surface 7. free cusp asudas turner et al. (1991) primary second lower molar, groove pattern lm2 +. cusp 1,2,3 and 4 are in contact x. cusp 1 and 4 are in contact y. cusp 2 and 3 are in contact sciulli (1998) permanent first lower molar, groove pattern lm1 y. cusp 2 and 3 are in contact +. cusp 1,2,3 and 4 are in contact x. cusp 1 and 4 are in contact asudas turner et al. (1991) primary second lower molar, cusp 6 lm2 0. absent 1. cusp 6 << cusp 5 2. cusp 6 < cusp 5 3. cusp 6 = cusp 5 4. cusp 6 > cusp 5 5. cusp 6 >> cusp 5 asudas turner et al. (1991) permanent lower first molar, cusp 6 lm1 0. absent 1. cusp 6 << cusp 5 2. cusp 6 < cusp 5 3. cusp 6 = cusp 5 4. cusp 6 > cusp 5 5. cusp 6 >> cusp 5 asudas turner et al. (1991) primary second lower molar, cusp 7 lm2 0. absent 1. through trace 2. small cusp 3. well developed hanihara (1961) permanent lower first molar, cusp 7 lm1 1. faint cusp (two weak grooves) 1a. fine cusp without free apex 2. small cusp 3. medium-sized cusp 4. large cusp asudas turner et al. (1991) appendix. trait descriptions l. aguirre et al. ranjitkar et al. 1999.1 pg01.jpg pg02.jpg pg03.jpg pg04.jpg pg05.jpg alvrus 2000.2 pg9.jpg pg10.jpg pg11.jpg pg12.jpg pg13.jpg guatelli-steinberg 2000.3 pg22.jpg pg23.jpg hattab et al. 1999.1 pg01.jpg pg02.jpg pg03.jpg pg04.jpg pg05.jpg pg06.jpg pg07.jpg pg08.jpg pg09.jpg gagnon 2004.2 44 45 the moche of north coastal perú were among the earliest new world societies to develop a bureaucratic state organization (moseley, 1992; bawden, 1996). the moche state (ad 200–800) was a centralized hierarchical society that controlled the entire moche valley and perhaps valleys to the north and south (fig. 1). the moche elite marshaled their economic resources to build large public works, such as roads and monumental ceremonial structures (hastings and moseley, 1975; moseley, 1975), and to dramatically increase arable land through canal construction (moseley and deeds, 1982). the elite also amassed great personal wealth, as indicated by archaeological excavations of wealthy tombs (donnan and castillo, 1992; alva and donnan, 1993). to exert their influence, the elite used ideological power manifested in public rituals held at large monuments, and iconography that supported state ideologies. physical power, in the form of warfare, conquest, and sacrifice, was also central to elite control (shimada, 1978; bawden, 1996; billman, 1996; bourget, 1996. 2001; verano, 2001). prior to the establishment of the state, societies in abstract the moche of north coastal perú were among the earliest new world societies to develop state socio-political organization. the moche state (ad 200800) was a centralized hierarchical society that controlled the moche valley as well as valleys to the north and south. prior to the establishment of the state, a series of less hierarchical organizations were present in the valley. irrigation agriculture has often been cited as central to development of the moche state. to test this assertion i examined 750 individuals recovered from the largest cemetery at the site of cerro oreja. although the most important occupation of cerro oreja was during the gallinazo phase (ad 1-200), many individuals were interred here during the earlier salinar period (400 -1 bc). consequently, the cerro oreja collection holds a key to understanding the development of one of the earliest and most extensive states in the americas. the teeth and/or alveoli of each individual were examined for the presence of dental caries, periodontal disease, abscesses, and antemortem tooth loss. my analysis suggests women and children did increasingly focus their diet on agricultural products. these findings seem to support the hypothesis that increased irrigation and reliance on agricultural production was fundamental to the development of the moche state. however, men’s diets remained consistent through time. status seems to have been of little import in determining diet before and during early periods of state development, in dramatic contrast to what we know of its importance during the zenith of the state’s power. i suggest that increasing differentiation of gender roles was important to the development of the state, and that gender differences may have been the most salient force in the transition to political hierarchy and social stratification in the moche valley. dental anthropology 2004;17(2):45-54. food and the state: bioarchaeological investigations of diet in the moche valley of perú celeste marie gagnon* department of anthropology, university of north carolina. chapel hill, nc 27599 *address for correspondence: c. m. gagnon, department of anthropology, university of north carolina at chapel hill,108 alumni building cb#3120, chapel hill, nc 27599-3120 email:bioarchcel@yahoo.com editor’s note: ms. gagnon’s paper was awarded ‘first runner up’ for 2004 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. celeste marie gagnon 46 47c.m. gagnon the valley were organized in less hierarchical political structures (topic and topic, 1978; brennan, 1980; topic, 1982; billman, 1997, 1999). it was the people of these societies who first opened the desert lands of the moche valley to agriculture (table 1). construction of the valley-wide canal system that enabled agriculture production began during the cupisnique phase (1800–400 bc), when approximately 4200m3 of canals were built, irrigating 4100 hectares. this system was expanded by approximately 60,000 m3 during the salinar phase (400–1 bc), allowing for the cultivation of 6750 to 7300 hectares. during the gallinazo and early moche phases (ad 1–400) no new land appears to have been brought under cultivation. later, the moche state doubled agricultural production through the irrigation of 12,550–13,200 hectares (billman, 2002). this dramatic increase in agricultural production has led researchers to suggest that in perú, as elsewhere, irrigation played a central role in state development (steward, 1949; rowe, 1963; moseley, 1974; haas, 1987). this is because staple crops could be produced on a grand scale in irrigated fields creating storable surpluses. by controlling these stores, elites financed their state building activities (d’altroy and earle, 1985; earle, 1997). because increased agricultural production is reflected in an increase in the consumption of agricultural products, the link between irrigation and state development can be tested by tracking prehistoric changes in diet. to this end, i examined individuals who lived during the salinar and gallinazo phases, just prior to and during the beginnings of state formation, for evidence of increased prevalence of dental pathological conditions indicative of the increased consumption of starchy and/or sugary agricultural products. an advantage of using biological rather then ethnobotanical data to chart consumption is that these data are linked to specific individuals for whom sex, age-at-death, and status information is known. this allowed me to examine not only changes in agricultural production, but who these changes affected, and thus link changes in social roles, particularly gender roles, to changes in political organization. fig. 2. map of the lower and middle moche valley locating cerro oreja, from billman 1999.fig. 1. perú with north coast inset, from moseley 1992. new canals ceremonial phase estimated dates cultural horizon1 excavated architecture middle moche ad 400–700 early intermediate period 312,000 m3 416,000 m3 gallinazo–early moche ad 1–400 early intermediate period 0 m3 15,000 m3 salinar 400–1 bc early intermediate period 60,000 m3 67,000 m3 cupisnique 1800–400 bc initial period–early horizon 42,000 m3 1,291,000 m3 table 1. moche valley cultural periods and work projects 1following moseley (1992) and billman (2002). 46 47food and the state the sample the remains i examined in this study were excavated by the instituto nacional de cultura (inc) from the site of cerro oreja (fig. 2). cerro oreja, located at the neck of the moche valley, was the largest urban center in the valley during the gallinazo phase (billman, 1999). downstream from this location the moche valley widens as the river drains into the pacific. at the neck and upstream, the río moche cuts into the andean foothills. here bottom land is limited and valley slopes rise steeply. it is in this area that people, both in the past and present, have built irrigation canal intakes. although the most important prehistoric occupation of cerro oreja was during the gallinazo phase, many individuals were also interred here during the salinar phase. of the 909 burials excavated from cerro oreja by the inc, i examined 681. several burials contained the remains of more than one individual, and as a result the study sample represents 750 individuals. the inc made phase designations based on burial goods and stratigraphic location. the sample i analyzed for this study included the remains of 61 salinar, 142 early gallinazo, 109 middle gallinazo and 69 late gallinazo individuals (table 2). although the mortuary analysis of the cerro oreja cemetery is in its preliminary stages, information about the presence of grave goods is available. using these data, i divided individuals into two status categories, those with goods and those without. age-at-death and sex identifications were made as a joint effort by the members of the cerro oreja bioarchaeology project, which is co-directed by dr. patricia lambert of utah state university and dr. brian billman of the university of north carolina at chapel hill. during the summer field seasons of 1999, 2000, and 2001, i worked with dr. lambert and bonnie yoshida, a graduate student at the university of california at santa barbara, to make age-at-death and sex estimations for 243 individuals. during an extended research season, yoshida identified the age-at-death and sex of an additional 183 individuals. in 2003, i examined these individuals as well as the remains of 324 additional individuals. our age-at-death and sex identifications were made following standards (buikstra and ubelaker, 1994). we based subadult age estimates primarily on tooth formation and eruption (white, 1991). skeletal development and fusion (johnston, 1962; fazekas and kósa, 1978; buikstra and ubelaker, 1994) were used in estimating the age-at-death of fetuses and infants, as well as of individuals for whom the dentition was not preserved. adult ages were estimated based on combined morphological changes at the pubic symphysis and auricular surface, and also on cranial suture closure (as presented in buikstra and ubelaker, 1994). occasionally sternal rib ends were well-enough preserved to be included in our age assessments (see bass, 1987). we assigned individuals a mean age and an error estimate. errors ranged from several months for well-preserved children to as much as 15 years for fragmentary adults. for this analysis, i grouped individuals in five-year categories based on their mean age. adult remains too fragmentary to be assigned a mean age were not included. sex identification of adults was established using the phenice method and qualitative observations of pelvic morphology, such as relative size of greater age in years salinar early gallinazo middle gallinazo late gallinazo fetal 0 5 8 0 birth 4.9 24 110 90 49 5 9.9 11 21 12 9 10 14.9 3 12 4 3 15 19.9 5 10 11 7 20 24.9 2 9 4 5 25 29.9 0 9 7 11 30 34.9 6 6 10 7 35 39.9 8 10 10 3 40 44.9 5 10 8 4 45 49.9 4 5 5 2 50 54.9 0 0 2 0 55 59.9 1 0 0 0 > 18 2 5 1 5 > 20 3 20 28 26 > 30 2 11 10 13 > 40 0 2 5 1 50 + 0 0 0 1 table 2. study sample 48 49 sciatic notch, length of the pubic ramus and width of the subpubic angle. we also considered cranial morphology and robusticity when sexing adults (white, 1991; buikstra and ubelaker, 1994). if the os pubis was extremely fragmentary or absent, we used metric data from the femora, tibiae, and humeri to support cranial sex identifications (iscan and miller-shaivitz, 1984; dittrick and suchey, 1986). not all individuals could be assigned a sex with the same degree of certainty. to incorporate our varying error, we employed a fourtier system to rank our identifications: female/male, probable female/male, possible female/male, and unidentified. individuals in the last two categories were excluded from this analysis. approximately 56% of the individuals in this study had preserved teeth and/or alveoli that i could examine for the presence of the following dental pathological conditions: caries, periodontal disease, abscesses, and antemortem tooth loss. methodological considerations biological anthropologists have effectively used the frequency of dental pathological conditions to chart changes in diet, particularly with regard to the consumption of agricultural products (see kelley and larsen, 1991; hillson, 1996; larsen, 1997). because of the nature of human dentitions and the vagaries of skeletal preservation, researchers have struggled with several sampling issues. the primary issue is scalar: should individuals or teeth be the unit of analysis? in an analysis at the individual level, individuals are diagnosed as having or not having a particular condition. such an analysis can provide researchers with useful information; but it can also obscure variation. at this level, an individual with 32 observable teeth, only one of which is carious, cannot be distinguished from an individual with 32 carious teeth, though these two individuals certainly had different diets. characterizing individuals by the percentage of affected teeth addresses this issue, but raises questions about sample comparability. an individual with 32 observable teeth, all of which are carious, and an individual with only two teeth, also carious, would both be classified as 100% affected. to mitigate the effects of individual preservation differences, researchers often exclude individuals who do not have some minimum number of observable teeth. in addition to these issues of comparability, substantial data loss occurs when each individual is characterized by only one datum point. in the comparison described above, 32 teeth were observed. however, when these data are analyzed at the individual level, there is only one datum point—the presence (or absence) of carious lesions, or the percentage of affected teeth. this loss can result in sample sizes that are insufficient to address research questions. to maximize data and address comparability difficulties, many researchers analyze their data at a higher scale (following turner, 1979). all the teeth of many individuals are pooled into groups, the boundaries of which are defined by the questions to be addressed. these types of studies yield some interesting information about diet. however, statistical analyses of data grouped in this way assume that each tooth in the group is independent of all others. this assumption does not hold, as the teeth of an individual are affected by her/his diet and are therefore more likely to resemble each other than the teeth of other individuals. additionally, the pooling of samples can increase group heterogeneity, leading to spurious results. to test for diet change over time, all individuals from each period can be grouped to create a lesion rate for each. statistical analysis of these rates may not identify significant differences among groups because the differences that do exist may average out. summary measures of a bimodal distribution (e.g., female teeth are always affected while male teeth are not) can be very similar to those of a standard distribution (e.g., both female and male teeth are often affected). to address this issue, groups can be more narrowly defined, creating a larger number of groups each of which includes fewer individuals. doing so, however, decreases sample size and the power of statistical tests to identify differences among the groups. two other factors complicate both individual and group level analysis: the differing susceptibility of different tooth types to dental pathological conditions, and the varying ages-at-death of sample individuals. teeth vary in their overall size and the complexity of their shape. both of these factors affect a tooth’s probability of developing pathological lesions. at the individual level of analysis for example, a person with eight observable anterior teeth is much less likely to display carious lesions than someone with eight observable molars. at the group level, samples pooled for comparison might contain substantially different distributions of tooth types. dental pathological conditions are also age-dependent. for this reason, researchers segregate subadults and adults in both individual and group level analyses. in some cases the adult sample is further divided into young, middle, and old categories. as with other attempts to mitigate sample heterogeneity, the level of error must to be balanced against decreasing the sample size. to address these persistent problems, i analyzed these data using logistic regression. a log-linear model simultaneously explores the complex relationships between a categorical independent variable, in this case the presence or absence of a dental condition, and any number of numeric and/or categorical dependent variables (e.g, age-at-death, sex). secondly, it solves the dilemma of analytical scale. model estimates c.m. gagnon 48 49 of population parameters are calculated using individual teeth, allowing the largest possible sample size. however, the teeth of an individual remained linked, preserving individual-level information. this nesting sampling strategy adjusts for sample-effects by weighting the value of the independent variable for each tooth according to how much additional information it provides about the individual. finally, interactions among dependent variables can be examined for significance. if two dependent variables vary simultaneously their interaction will be more significantly associated with the independent variable than either would when independently analyzed. the model i used in this analysis was programmed in sas with the help of chris wiesen, staff statistician for the odum institute at the university of north carolina at chapel hill. in this model age-at-death was the only numeric, dependent variable. we treated this variable as numeric because it behaved linearly, even when described in 5-year intervals. the categorical variables we included were period, status, sex, and tooth-type. period, status, and sex identifications have been discussed above. i defined several toothtypes based on differing susceptibility of each type to various dental conditions. all teeth were assigned to either one of four permanent types (anterior, premolar, first or second molar, third molar), or to one of three deciduous types (anterior, first molar, second molar). this classification allowed us to modify the model so that it accounted for variation in the number of teeth from each type that were observable in each individual. additionally, tooth-types were weighted based on their expected occurrence in the population (0.375, 0.25, 0.25, and 0.125, 0.6, 0.2, 0.2, respectively). the inclusion of these dependent variables in the model controlled for variation in the analysis without breaking the sample down into multiple subgroups, thus preserving sample size. results permanent and deciduous teeth were considered separately in all analyses. the first analytical step was to calculate rates of dental pathological conditions at both individual and tooth levels. i grouped all individuals who had at least one observable tooth by their status, and compared the percentage of people affected by each condition across periods. no significant status differences were identified (table 3). similarly, no significant status differences were found when teeth were grouped by status and compared across time (table 4). differing patterns were found when adult individuals, and the teeth of adults, were divided into female and male samples and compared across periods (table 5 and 6). therefore, a sex-by-period interaction was included in the log-linear model, and individuals of unknown sex were excluded from further analyses. as part of the logistic regression, the wald statistic was calculated to test the null hypothesis that groups are characterized by similar rates of dental pathological conditions. to create a visual representation of these data, rates of dental conditions, adjusted for sample variations in size, age-at-death, and tooth-type, were plotted. deciduous teeth affected by carious lesions generally increased through time (fig. 3), although this pattern is not statistically significant (p < 0.2680). female adult carious lesions rates show a similar trend (fig. 4), which is significant (p < 0.0077). temporal variation in male carious lesion rates are not significant (p = 0.4903), and shows no pattern (fig. 4). significant differences were identified between female and males in the middle and late gallinazo phases (p = 0.0051 and 0.0286, deciduous permanent permanent period carious carious periodontal permanent permanent status lesions lesions disease abscesses tooth loss n % n % n % n % n % salinar high 28 25 31 74 14 86 17 47 19 68 low 1 0 5 100 3 100 3 67 3 33 early gallinazo high 27 37 36 64 6 83 21 43 22 59 low 35 29 42 50 7 71 15 47 16 69 middle gallinazo high 10 30 21 71 7 86 15 53 16 63 low 32 44 36 61 12 67 20 35 24 58 late gallinazo high 4 25 11 73 4 100 6 17 6 67 low 21 29 18 67 7 43 11 45 11 55 table 3. individuals affected by dental pathological conditions food and the state 50 51 respectively). adult periodontal disease rates show changes over time for both females (p = 0.2383) and males (p = 0.0871), but the pattern of change is different than that seen in carious lesion rates (fig. 5). among both females and males periodontal disease rates increased from the salinar to the early gallinazo phase and then fell from the early to the middle gallinazo. throughout these periods, female rates were higher than males, but these differences are only marginally significant during the early gallinazo phase (p = 0.0961). the female and male patterns dramatically change in the late gallinazo phase, when there is a significant increase in periodontal disease among males (p = 0.0286), but female rates continue to fall. dental abscessing and antemortem tooth loss among females and males display no clear temporal patterns. females are more often affected by these conditions than males (figs. 6 and 7). differences in the rates of abscessing are only statistically significant during the middle gallinazo phase (p = 0.0536). antemortem tooth loss differences between females and males are significant during the salinar (p = 0.0257) and middle gallinazo (p = 0.0286). discussion what do the various measure of dental pathological conditions tell us about agricultural consumption at the site of cerro oreja during the periods preceding the development of the state? carious lesion rates suggest that adult females, and to a lesser extent children, carbohydrate consumption steadily increase through time (figs. 3 and 4). this seems to support the hypothesis that an intensification of agricultural c.m. gagnon period deciduous permanent permanent status carious carious periodontal permanent permanent lesions lesions disease abscesses tooth loss n % n % n % n % n % salinar high 263 20 350 18 236 39 360 7 616 13 low 15 0 81 12 69 30 113 7 159 3 early gallinazo high 153 16 287 21 62 24 281 12 683 11 low 217 10 293 19 116 45 310 13 717 12 middle gallinazo high 62 13 159 30 92 20 170 12 409 11 low 262 15 323 21 47 45 260 7 627 7 late gallinazo high 98 11 69 35 54 41 75 7 196 23 low 29 10 154 23 22 73 217 8 478 7 table 4. teeth affected by dental pathological conditions fig. 3. deciduous carious lesion rates by period. fig. 4. carious lesion rates for females and males by period. 50 51 period carious periodontal permanent permanent sex lesions disease abscesses tooth loss n % n % n % n % salinar female 9 87 7 86 9 56 9 89 male 7 86 7 86 7 29 7 43 early gallinazo female 12 83 6 100 14 43 14 86 male 16 63 7 86 19 58 20 65 middle gallinazo female 15 93 10 80 17 53 20 75 male 7 57 7 86 10 30 11 64 late gallinazo female 7 86 8 75 10 40 10 70 male 4 50 3 67 6 17 6 50 table 5. individuals affected by dental pathological conditions production, and a correlated increased in staple consumption, was central to the development of the moche state. however, adult male consumption does not follow this pattern (fig. 4). rather, it appears that males consumed fewer starchy and/or sugary staple agricultural products than did children and females, in amounts that did not change over time. an increasingly different diet among males, compared to females and children suggests increasingly differentiated gender roles in society. what kinds of changes in gender roles might have resulted in such different diets? as a point of comparison i offer the inka state’s policy of mit’a labor, in which men were required to work on large-scale, state-sponsored projects. while taking part in such work parties laborers were supplied with specialized food-stuffs (d’altroy and earle, 1985; hastorf, 1990, 1991, 1993). similarly, the substantial investment in public construction in the moche valley throughout the study period would certainly have required elites to marshal and supply a sizable work force (table 1). therefore, i suggest that the men of cerro oreja were being increasingly drafted by the elite into similar work parties where they were provisioned with, or offered as an enticement, meat and/or marine resources, while women and children continued to tend agricultural fields and consume the staple crops they produced. periodontal disease rates do not follow the same pattern as carious lesion rates, for either females or males (fig. 5). this suggests that periodontal disease in the cerro oreja sample is not as closely linked to consumption as carious lesion rates. to understand this pattern i examined how non-food items that people put into their mouths can affect the oral environment. food and the state period carious periodontal permanent permanent sex lesions disease abscesses tooth loss n % n % n % n % salinar female 107 17 82 54 150 1 233 13 male 111 22 90 46 130 6 199 7 early gallinazo female 109 32 45 76 148 14 284 18 male 123 28 45 64 161 23 367 17 middle gallinazo female 126 43 45 44 152 13 351 15 male 54 15 31 42 83 6 176 10 late gallinazo female 59 53 32 34 85 8 184 17 male 54 13 13 77 44 2 96 6 table 6. teeth affected by dental pathological conditions 52 53 coca leaf chewing is a common activity in the andes with a very long history (rostworoski, 1988; plowman, 1985; allen, 1985, 1988). because of the stimulant qualities of coca and the corrosive nature of the lime with which coca leaves are chewed, this activity is associated with alveolar resorption, periodontal disease, and the development of carious lesions in the subsequently exposed tooth roots (langsjoen, 1996; indriati, 1997; indriati and buikstra, 2001). unfortunately, the poor curation of the cerro oreja skeletal collection resulted in the fragmentation of many tooth roots, thus the rate of root lesions could not be compared to that of crown lesions. such a comparison could have provided support for my interpretation. archaeological investigations in the moche valley provide information relevant to the question of coca use at cerro oreja. billman (1996, 1997) has identified an in-migration of highland people into the moche valley during the beginning of the gallinazo phase, based on the appearance of sites dominated by highland ceramics. of particular interest is the highlander occupation of the limited coca growing areas located in the upper portion of the middle valley. the occupation of these areas by highlanders may have resulted in a reduced access to and use of coca by local residents, as indicated by the decrease in periodontal disease from the early to the middle gallinazo period. billman proposed that these distinctive highland sites were abandoned as highlanders were displaced, absorbed, and/or eliminated by the end of the gallinazo phase. in the late gallinazo coca may again have been available to valley residents, but increasing gender role differentiation resulted in its use by men, not women. since coca chewing increases work capacity (allen, 1985; plowman, 1985), this may again be an example of elites provisioning men as they labor on irrigation and ceremonial construction projects. beyond coca’s dramatic biological effects, it has, and has had, important religious and social significance to andeans (isbell, 1978; allen, 1985, 1988; weismantel, 1988). thus i would suggest, that its effects on work capacity is only part of the story. the moche valley elite may have offered coca as payment to common men for their labor, and in this way engaged them as willing participants in their state-building projects. female and male rates of dental abscesses and antemortem tooth loss show little difference and no patterned change over time (figs. 6 and 7). because these are not primary conditions, but are the result of untreated dental caries (crown or root), periodontal disease and/or dental wear, this lack of temporally patterned variation may be the result of an “averaging” c.m. gagnon fig. 5. periodontal disease lesion rates for females and males by period. fig. 6. abscess rates for females and males by period. fig. 7. antemortem tooth loss rates for females and males by period. 52 53food and the state of the effects of these primary pathological conditions. conclusion in this analysis i tested the hypothesis that the development of the moche state (ad 200–800), one of the earliest and most hierarchical in the americas, was based on intensification of irrigation agriculture. this hypothesis is based on the dramatic increase of arable land in the moche valley during the salinar and gallinazo phases, prior to the development of the state and during the early period of state development (table 1). as people increased agricultural production, they would also have increased their consumption of starchy and/or sugary agricultural products. my analysis suggests women and children did increasingly focus their diet on agricultural products (figs. 3 and 4). these findings seem to confirm the hypothesis that increased irrigation and reliance on agricultural production was fundamental to the development of the moche state. however, the story is more complex. men’s diets remained consistent through time (fig. 4). additionally the data suggest that women and men’s use of coca varied temporally, in significantly different ways (fig. 5). status seems to have been of little import in determining diet before and during early periods of the state, in dramatic contrast to what we know of its importance during the zenith of the state’s power. together these data suggest that increasing differentiation of gender roles was important to the development of the state. gender differences may have been the most salient force in the transition to political hierarchy and social stratification in the moche valley. acknowledgments major support for this research was provided by the national science foundation (0225011). the university of north carolina at chapel hill institute for latin american studies and graduate college, sigma xi, and the wenner-gren foundation (6623) provided additional funding. i would like to thank dr. brian billman and dr. patricia lambert for the opportunity to work with the cerro oreja skeletal material, the danger girls for their guidance in producing this document, and michael scholl for his unfailing support, which made this project possible. literature cited allen cj. 1985. coca and cultural identity in andean 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1980. cerro arena: early cultural complexity and nucleation in north coastal peru. j field archaeol 7:1-22. buikstra je, ubelaker dh, editors. 1994. standards for data collection from human skeletal remains. fayetteville: arkansas archeological survey. research series, no. 44. d’altroy t, earle tk. 1985. staple finance, wealth finance, and storage in the inka political economy. current anthrop 26:187-206. dittrick j, suchey jm. 1986. sex determination of prehistoric central california skeletal remains using discriminate analysis of the femur and humerus. j am anthrop 70:3-9. donnan cb, castillo lj. 1992. finding the tomb of a moche priestess. archaeol 45:38-42. earle t. 1997. how chiefs come to power. stanford, ca: stanford university press. 54 55 fazekas ig, kósa f. 1978. forensic fetal osteology. budapest: akadémiai kiadó. haas j. 1987. the exercise of power in early andean state development. in: haas j, pozorski s, pozorski t, editors. the development and origins of the andean state. cambridge: cambridge university press, p 31-35. hastings cm, moseley me. 1975. the adobes of huaca del sol and huaca de la luna. am ant 40:196-203. hastorf ca. 1990. the effect of the inka state on sausa agricultural production and crop consumption. am ant 55:262-290. hastorf ca. 1991. gender, space, and food in prehistory. in: gero jm, conkey mw, editors. engendering archaeology, women and prehistory. cambridge: blackwell publishers, p 132-159 hastorf ca. 1993. agriculture and the onset of political inequality before the inka. cambridge: university press. hillson s. 1996. dental anthropology. cambridge: cambridge university press. indriati e. 1997. the effects of coca chewing on teeth and the prehispanic distribution of coca chewing. am j phys anthropol suppl. 24:134-135. indriati e, buikstra je. 2001. coca chewing in prehistoric coastal peru: dental evidence. am j phys anthropol 114:242-257. isbell bj. 1978. to defend ourselves: ecology and ritual in an andean village. 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25, p 77-82. moseley me. 1992. the incas and their ancestors. london: thames and hudson. moseley me, deeds ee. 1982. the land in front of chan chan: agrarian expansion, reform, and collapse in the moche valley. in: moseley me, deeds ee, editors. chan chan: andean desert city. albuquerque: university of new mexico press, p 25-53. plowman t. 1985. coca chewing and the botanical origins of coca (erythroxylum spp.) in south america. in: pacini d, franquemont c, editors. coca and cocaine: effects on people and policy in latin america. cambridge: cultural survival inc, p 5-33. rostworowski mdc. 1988. conflicts over coca fields on xvth-century perú. ann arbor: memoirs of the museum of anthropology, university of michigan, no. 1. rowe j. 1963. urban settlements in ancient peru. ñawpa pacha 1:1–27. shimada i. 1978. economy of a prehistoric urban context: commodity and labor flow at moche v pampa grande, peru. am ant 43:569-592. steward jh. 1949. cultural causality and law: a trial formulation of the development of early civilizations. am anthropol 51:1–27. topic jr, topic tl. 1978. prehistoric fortification systems of northern perú. current anthropol 19:618-619 topic tl. 1982. the early intermediate period and its legacy. in: moseley me, deeds ee, editors. chan chan: andean desert city. albuquerque: university of new mexico press, p 255-284. turner cg. 1979. dental anthropological indications of agriculture among the jomon people of central japan. am j phys anthropol 51:619-636. verano jw. 2001. the physical evidence of human sacrifice in ancient peru. in: benson ep, cook ag, editors. ritual sacrifice in ancient peru. austin: university of texas press, p 165-184. weismantel mj. 1988. food, gender, and poverty in the ecuadorian andes. prospect heights: waveland press. white td. 1991. human osteology. new york: academic press. c.m. gagnon guatelli-steinberg 2000b.5 pg38.jpg pg39.jpg turner 2005.4 55 this note is based on observations made on a small sample of prehistoric human teeth from excavations on rotuma island submitted to the author for analysis by richard shutler, jr. he and jamie evrard directed test excavations in june and july, 1981, one resulting in the recovery of human remains from rot 2-9, an archaeological site in the oinafa district location called risumu on the east end of rotuma island. rotuma is remotely located in the mid-pacific. volcanic in origin and only 25 km2 in area, it is in the western polynesian outlier culture division of oceania at approximately 12˚ 25’ s and 177˚ 5’ e. the risumu site is the legendary landing place of the first immigrants, supposedly from tonga, who are said to have arrived about one thousand years ago (shutler and evrard, 1991:136). the people of tonga are polynesians, and the present-day rotuma islanders speak a language that is classified as polynesian, although its exact genetic relationship to other polynesian languages is unclear (shutler, 1998: 252). melanesian populations occupy the solomon islands to the west and fiji to the south, whereas polynesians are settled on samoa to the east. the human remains were found in a burial mound (rot 2-9, test 4, level 4) at a depth of 90-100 cm. there were no cultural remains associated with the human teeth and bones. this small but geographically rare assemblage has since been reburied after study. however, before reburial shutler had a sample of the human bone dated in the carbon 14 laboratory on his campus at simon fraser university, burnaby, british columba, canada. the assay (sfu-118) produced an uncorrected date of 1,000 bp + 100 radiocarbon years (shutler, 1998). dental indications of polynesian affinity for prehistoric rotuma islanders, south pacific christy g. turner ii* department of anthropology, arizona state university, tempe *correspondence to: christy g. turner ii, department of anthropology, arizona state university, tempe, az 85287-2402 e-mail: christyturner@aol.com abstract human skeletal reburial, reasonable from a religious and personal point of view, nevertheless diminishes the physical record of human evolution. the present study preserves some information for a small but rare pacific basin skeletal assemblage. prehistoric human tooth-bearing cranial and jaw fragments and loose teeth of probably 19 individuals excavated on rotuma island were examined for crown and root morphology. the purpose of the examination was to assess whether these individuals were morphologically more like melanesians or polynesians. rotuma is in the polynesian culture area north of the fiji group, which exhibits archaeological and ethnographic evidence of colonists from both oceanic populations. polynesians belong to the malayo-polynesian language family, so if the rotuma teeth are similar to polynesians they should also be more similar to southeast asian teeth than to those of linguistically different melanesians or australians. indeed, this seems to be the case, although the small rotuma sample size reduces confidence somewhat in this finding of rotuma similarity with polynesians and southeast asians. dental anthropology 2005;18(2):54-60. materials and methods the number of rotuma individuals based on maxillary teeth is 14; mandibular teeth, 17; maxillary and mandibular, 18; probable total, 19. following standardized observation and scoring procedures for non-metric dental traits (turner et al., 1991), crown and root morphology was analyzed by univariate and multivariate statistics to estimate rotuma’s phenetic dental relationships with selected comparative populations. the regions chosen for comparison were (1) south pacific, because of geographic proximity; (2) southeast asia, because of ultimate linguistic homeland; and (3) native america because of t. heyerdahl’s (1952) hypothesis that polynesians originated from the americas. although large samples are always desired in assessing affinity for archaeologically-derived and usually incomplete and fragmentary skeletal samples, it appears that the rotuma series is adequate for moderately confident inferences about probable past inter-group relationships. the ten comparative dental series used to identify rotuma relationships are part of the published and unpublished data base in the author’s computer and other files. the traits selected for comparison are those that occur most frequently in the rotuma series. incisor shoveling, for example, was used because some teeth are present with, and have limited wear of, the trait that permits confident scoring, 56 rotuma dentition t a b l e 1 . d en ta l t ra it fr eq u en ci es in r ot u m a an d co m pa ra ti ve s er ie s b re ak . e as te r n ew n w to ot h tr ai t p oi n t r ot u m a m ar q u es . ta h it i is la n d g u am b ri ta in a u st ra li a t h ai la n d in d on es ia p er u c oa st u i1 w in gi n g 1/ 14 50 .0 ( 2) 16 .0 ( 50 ) — ( 0) — ( 0) 18 .2 ( 22 ) 25 .0 ( 11 2) 13 .3 ( 30 ) 31 .0 ( 42 ) 14 .8 ( 61 ) 83 .7 ( 49 ) 33 .3 ( 66 ) u i2 sh ov el 27/ 07 66 .7 ( 6) 41 .5 ( 70 ) 10 0. 0 (1 ) 0. 0 (1 ) 50 .0 ( 34 ) 21 .6 ( 13 0) 45 .8 ( 24 ) 60 .4 ( 48 ) 67 .3 ( 58 ) 97 .7 ( 43 ) 96 .8 ( 63 ) u i1 d u bsh ov . 26/ 06 50 .0 ( 4) 9. 4 (6 4) 0. 0 (1 ) — ( 0) 5. 6 (3 6) 3. 7 (1 07 ) 7. 4 (2 7) 12 .5 ( 48 ) 30 .5 ( 59 ) 93 .8 ( 16 ) 51 .0 ( 49 ) u i2 tu b. d en ta l + / + , 0 66 .7 ( 6) 60 .9 ( 46 ) 0. 0 (1 ) 0. 0 (1 ) 83 .3 ( 6) 45 .8 ( 12 0) 54 .5 ( 22 ) 47 .2 ( 36 ) 63 .8 ( 47 ) 52 .9 ( 34 ) 77 .0 ( 61 ) u c b u sh m an 13/ 03 0. 0 (8 ) 1. 4 (7 4) 0. 0 (2 ) 0. 0 (1 ) 2. 8 (3 6) 2. 2 (1 37 ) 8. 3 (2 4) 2. 4 (4 2) 2. 2 (8 9) 0. 0 (6 0) 0. 0 (8 7) u c d a r 25/ 05 83 .3 ( 6) 69 .2 ( 39 ) — ( 0) — ( 0) 79 .0 ( 19 ) 36 .6 ( 60 ) 80 .0 ( 5) 72 .2 ( 18 ) 77 .8 ( 54 ) 81 .0 ( 21 ) 85 .3 ( 34 ) u p 1 u to -a zt ec + / + , 0 0. 0 (6 ) — ( 0) — ( 0) — ( 0) 0. 0 (8 ) — ( 0) 0. 0 (9 ) 0. 0 (3 1) 0. 0 (4 ) 0. 0 (1 18 ) 0. 0 (3 4) u m 3 m et ac on e 15/ 05 10 0. 0 (5 ) — ( 0) — ( 0) — ( 0) 10 0. 0 (6 ) — ( 0) 10 0. 0 (3 ) 10 0. 0 (3 1) 10 0. 0 (1 ) 98 .1 ( 10 7) 10 0. 0 (1 3) u m 2 h yp oc on e 15/ 05 10 0. 0 (4 ) 98 .3 ( 12 1) 10 0. 0 (6 ) 10 0. 0 (9 ) 96 .4 ( 56 ) 97 .2 ( 17 9) 10 0. 0 (4 5) 97 .1 ( 70 ) 93 .8 ( 19 5) 94 .7 ( 24 4) 93 .2 ( 14 8) u m 1 c u sp 5 15/ 05 25 .0 ( 8) 61 .5 ( 13 0) 10 0. 0 (5 ) 66 .7 ( 6) 47 .7 ( 44 ) 68 .4 ( 15 5) 79 .2 ( 24 ) 34 .9 ( 63 ) 33 .7 ( 18 1) 15 .4 ( 16 2) 24 .0 ( 12 1) u m 1 c ar ab el li 28/ 08 22 .2 ( 9) 37 .4 ( 15 5) 16 .7 ( 6) 10 .0 ( 10 ) 36 .2 ( 47 ) 41 .9 ( 17 7) 45 .8 ( 24 ) 39 .4 ( 61 ) 38 .7 ( 20 9) 38 .6 ( 16 3) 23 .4 ( 12 4) u m 3 p ar as ty le 15/ 05 0. 0 (5 ) 5. 4 (5 6) 0. 0 (2 ) 0. 0 (1 ) 0. 0 (6 ) 5. 7 (1 23 ) 7. 7 (5 2) 0. 0 (3 4) 2. 3 (8 6) 4. 7 (1 28 ) 3. 9 (1 29 ) u m 1 e n am el e xt 13/ 03 44 .4 ( 9) 45 .5 ( 14 5) 55 .6 ( 9) 46 .2 ( 13 ) 31 .4 ( 51 ) 20 .7 ( 15 0) 50 .7 ( 73 ) 47 .5 ( 80 ) 66 .5 ( 22 1) 66 .5 ( 31 0) 71 .6 ( 22 2) u l p 12 o d on to m e + / + , 0 0. 0 (1 0) 1. 5 (1 35 ) 0. 0 (8 ) 0. 0 (1 4) 20 .0 ( 5) 2. 1 (1 46 ) 0. 0 (2 7) 0. 0 (1 1) 1. 7 (1 15 ) 3. 2 (1 54 ) 5. 2 (9 7) u p 1 1ro ot 1/ 13 87 .5 ( 8) 60 .0 ( 13 5) 80 .0 ( 15 ) 87 .0 ( 23 ) 49 .1 ( 57 ) 48 .8 ( 12 5) 59 .3 ( 81 ) 52 .2 ( 67 ) 53 .9 ( 26 7) 89 .3 ( 28 0) 90 .9 ( 23 1) u m 2 3ro ot 35/ 15 10 0. 0 (3 ) 61 .7 ( 12 0) 36 .4 ( 11 ) 40 .0 ( 20 ) 82 .0 ( 50 ) 86 .3 ( 13 9) 76 .7 ( 60 ) 85 .3 ( 34 ) 78 .0 ( 22 3) 44 .8 ( 23 9) 43 .4 ( 19 1) u m 3 r ed / p eg / ca + / + , 0 0. 0 (5 ) 40 .0 ( 95 ) 25 .0 ( 8) 46 .2 ( 13 ) 81 .5 ( 27 ) 16 .7 ( 15 6) 10 .1 ( 69 ) 29 .5 ( 44 ) 41 .7 ( 17 5) 20 .9 ( 30 2) 8. 1 (1 86 ) l p 2 > 1 l c u sp 23/ 03 10 0. 0 (7 ) 90 .0 ( 90 ) 10 0. 0 (4 ) 87 .5 ( 16 ) 93 .9 ( 33 ) 91 .5 ( 15 3) 91 .3 ( 23 ) 87 .5 ( 56 ) 81 .4 ( 70 ) 24 .4 ( 82 ) 40 .5 ( 79 ) l m 1 a n te ri or f ov ea 15/ 05 10 0. 0 (6 ) — ( 0) — ( 0) — ( 0) 10 0. 0 (4 ) — ( 0) — ( 0) 66 .7 ( 3) — ( 0) 88 .1 ( 59 ) 85 .7 ( 7) l m 2 y g ro ov e y / y, + , x 22 .2 ( 9) 16 .4 ( 11 6) 33 .3 ( 9) 12 .5 ( 16 ) 18 .5 ( 65 ) 25 .4 ( 18 1) 19 .1 ( 47 ) 20 .5 ( 73 ) 15 .8 ( 10 1) 7. 9 (1 52 ) 12 .4 ( 13 7) l m 1 c u sp 6 6/ 46 71 .4 ( 7) 55 .0 ( 10 9) 71 .4 ( 7) 37 .5 ( 8) 53 .7 ( 54 ) 49 .0 ( 15 7) 54 .5 ( 22 ) 22 .6 ( 62 ) 34 .6 ( 81 ) 63 .7 ( 91 ) 40 .7 ( 91 ) l m 2 4cu sp s 34/ 36 28 .6 ( 7) 39 .6 ( 10 6) 33 .3 ( 9) 53 .8 ( 13 ) 13 .6 ( 59 ) 51 .8 ( 17 0) 12 .5 ( 32 ) 44 .1 ( 68 ) 37 .1 ( 97 ) 9. 4 (1 59 ) 2. 9 (1 36 ) l m 1 d efl ec ti n g w r. 13/ 03 85 .7 ( 7) 56 .8 ( 74 ) 10 0. 0 (3 ) — ( 0) 74 .4 ( 43 ) 59 .8 ( 10 7) 40 .0 ( 10 ) 73 .1 ( 26 ) 54 .5 ( 44 ) 65 .5 ( 58 ) 51 .1 ( 45 ) l m 1 tr ig on id c re st + / + , 0 12 .5 ( 8) 1. 4 (7 2) 0. 0 (6 ) 0. 0 (8 ) 0. 0 (6 ) 0. 0 (1 13 ) 5. 6 (1 8) 0. 0 (1 6) 7. 8 (5 1) 3. 3 (1 21 ) 11 .3 ( 71 ) l m 1 p ro to st yl id 18/ 08 62 .5 ( 8) 13 .9 ( 12 2) 14 .3 ( 7) 30 .0 ( 10 ) 30 .0 ( 60 ) 21 .2 ( 18 9) 6. 7 (3 0) 40 .8 ( 76 ) 35 .6 ( 90 ) 26 .9 ( 16 0) 37 .2 ( 11 3) l m 1 c u sp 7 15/ 05 0. 0 (9 ) 7. 2 (1 25 ) 12 .5 ( 8) 0. 0 (1 3) 11 .8 ( 68 ) 13 .0 ( 19 2) 6. 2 (3 2) 11 .5 ( 87 ) 10 .9 ( 10 1) 10 .8 ( 16 7) 7. 9 (1 27 ) l c 2ro ot s 2/ 12 0. 0 (4 ) 0. 0 (1 00 ) 0. 0 (1 5) 0. 0 (2 7) 0. 0 (5 5) 0. 0 (9 7) 0. 0 (6 0) 0. 0 (3 6) 0. 0 (9 2) 1. 5 (1 99 ) 0. 0 (1 56 ) l m 1 3ro ot s 34/ 14 10 .0 ( 10 ) 2. 1 (1 41 ) 23 .1 ( 13 ) 7. 4 (2 7) 0. 0 (7 5) 4. 5 (1 55 ) 6. 9 (7 2) 8. 9 (9 0) 12 .2 ( 13 1) 5. 1 (2 17 ) 16 .4 ( 21 4) l m 2 1ro ot 1/ 14 44 .4 ( 9) 24 .2 ( 12 0) 20 .0 ( 15 ) 26 .9 ( 26 ) 9. 5 (6 3) 2. 0 (1 49 ) 6. 8 (7 3) 11 .9 ( 67 ) 27 .3 ( 12 1) 35 .2 ( 18 2) 36 .3 ( 20 1) l p 1 to m es r oo t 45/ 05 0. 0 (2 ) 0. 0 (8 5) 20 .0 ( 15 ) 3. 6 (2 8) 0. 0 (7 ) 10 .6 ( 94 ) 14 .8 ( 54 ) 7. 3 (4 1) 11 .1 ( 90 ) 2. 3 (8 6) 11 .5 ( 16 5) 57 whereas other traits are either absent (missing data) or their amount of occlusal wear exceeds the maximum for confident scoring (see various comments about wear in turner et al., 1991). most of these crown traits, but not the root traits, have been previously subjected to hereditary study and are believed to have a strong genetic component in their occurrence and expression (scott, 1973; harris, 1977; nichol, 1990). table 1 shows the various trait frequencies for rotuma and the comparative assemblages. counts are by individuals, sexes are pooled, and dichotomizing frequency break points are identified in table 1, which are necessary for the computation of both chi-square and the multivariate mean measure of divergence statistic (berry and berry, 1967; sjøvold, 1973). this multivariate statistic is preferred over others because of its relative simplicity and because it readily handles the problem of missing data. results univariate comparisons using chi-square (1 df, yates corrected when any expected cell is less than 5, p significant at 0.05, all observed cells had to be greater than 0) between rotuma and the ten comparative oceanic and circum-pacific samples in table 1 gave the following percentages of significant trait frequency differences: rotuma and easter, 0.0% (0 out of 23 possible comparisons); indonesia, 0.0% (0/29); marquesas, 3.7% (1/27); tahiti, 4.0% (l/25); thailand, 6.7% (2/30); guam, 6.7% (2/30); peru, 6.7% (2/30); northwest coast of alaska and western canada, 10.0% (3/30); australia, 10.3% (3/29); new britain, 14.8% (4/27). in terms of culture area and linguistic family classifications, easter, marquesas, and tahiti are polynesian; indonesia and thailand are southeast asian; guam is micronesian; australia and new britain are australmelanesian; and northwest coast and peru (the two areas that hyerdahl suggested polynesians might have come from) are native american-amerind. the rotuma dental traits that showed significant inter-group frequency differences were: shoveling (rotuma vs. new britain, 2 = 4.3; peru, 4.5; northwest coast, 4.7); double-shoveling (new britain, 8.6); upper molar cusp 5 (tahiti, 4.3; new britain, 5.3; australia, 6.7); peg-reduced-congenitally absent upper third molars (guam, 10.1); >1 lingual cusp of lower second premolar (northwest coast, 7.1; peru, 14.3); lower molar cusp 6 (thailand, 6.0); 4-cusped lower second molar (northwest coast, 5.9); protostylid (new britain, 5.8; marquesas, 9.4; australia, 10.9); 1-rooted lower second molar (thailand, 4.7; guam, 6.0; australia, 8.8; new britain, 27.7). several nearly significant frequency differences possibly would have been significant had the rotuma series been larger, and these differences likely would have enhanced the differences between rotuma and the australmelanesian and american dental series. since five percent significant differences can be expected on the basis of chance alone, these univariate comparisons suggest that this rotuma dental sample is statistically indistinguishable from those originating in the marquesas, tahiti, easter, and indonesia locations (which includes teeth from younger levels at niah cave, malay near singapore, other malays, philippines, bangkok, and the atayal of taiwan), and only barely distinguishable from teeth from guam, thailand (archaeological don klang, ban tong, non nok tha, and ban chiang pooled), and peru. the rotuma dental sample is easily distinguished from those originating in new britain, north and south australia, and northwest coast of north america. univariate comparisons show rotuma to be indistinguishable from the known polynesian samples. compared with australmelanesians, rotuma and the polynesians possess relatively high frequencies of incisor shoveling, deflecting wrinkle, protostylid, 3-rooted lower first molar, and 1-rooted lower second molars. they have low frequencies of the pronounced mesial-ridged upper canine (bushman canine), carabelli’s cusp, and the parastyle. these frequencies are characteristic of the southeast asian dental pattern i have called sundadonty in contrast to the northeast asian and new world pattern termed sinodonty (turner, 1979, and elsewhere). multivariate comparisons were made using 23 to 30 traits available in the comparative samples (table 2). because the rotuma series is small, few of the computed mean measures of divergence (mmd) are significant. this coupled with the fact that the number of traits compared differed slightly between comparative pairs, indicates that more reliability should be placed on the univariate findings and inferences. definitely, no strictly “literal” interpretation should be made of the mmd values, however, relatively, they generally follow what was inferred from the univariate comparisons. given that the number of trait pairs was not identical in all inter-group comparisons, i perhaps should have attempted to “standardize” the mmd values. it is a happy coincidence that i did not, because following the submission of this article to dental anthropology, i have read the important article by harris and sjøvold (2004) that, among other mmd considerations, convincingly demonstrates the inappropriateness of mmd standardization. as with the univariate comparisons, the mmd values of table 2 show that rotuma is more like most polynesians than like new britain. australia occupies an intermediate position, both in relation to rotuma (mmd = 0.061) and new britain (mmd = 0.057). rotuma has no measurable mmd dissimilarity to tahiti, thailand and indonesia, and effectively no divergence from easter. this odontological association of rotuma with polynesians and southeast asians is c.g. turner ii 58 quite suggestive of proximate (when the rotuma people were alive) and close ties with known polynesians, and close ultimate links with southeast asian sundadonts. insofar as sample size permits, rotuma cannot be multivariately distinguished from polynesians, whereas it can be when compared with melanesians. since polynesian and melanesian populations are the most realistic geographic sources for this rotuma sample, the former are a better bet than the latter for having been close relatives. the micronesian people of guam belong to the sundadont dental class, so it is not unexpected that inter-group similarities and differences parallel those of rotuma. given the very great oceanic distance separating guam and rotuma, their relative similarity is best attributed to their shared ultimate sundadont ancestry in southeast asia. a similar inference was made earlier by harris et al. (1975:231) regarding the stronger dental relationships between the yaps of micronesia and polynesians, in contrast to the much weaker relationship between yaps and australmelanesians. in large-scale comparisons, both pietrusewsky (1990), using craniometric observations, and the author (turner, 1990) using dental morphology, found guam skulls and teeth to be much more like those of southeast asians and polynesians than like various australian, melanesian, and tasmanian samples. however, when turner pooled rotuma and fiji dental samples, because of their relative oceanic closeness, this combined group was most like samples from early malay archipelago, and from melanesian-polynesian border islands. fiji has a history of both polynesian and melanesian occupation. the fiji dental sample was considered to be polynesian, but it would appear this was incorrect because the fiji-rotuma combination clustered with australmelanesians instead of sundadont southeast asians, polynesians, and guam micronesians. yet, the study by weets (1996) on the dentition of vanuatu islanders, near fiji, in eastern melanesia, found that these people were more like polynesians and east asians than like melanesians. hence, large-scale boundaries in oceania defined culturally and linguistically generally have high correspondence with dentally-defined communities. rotuma alone classifies as polynesian, but when combined with nearby fiji its affiliation becomes ambiguous. discussion both univariate and multivariate statistical comparisons of the small rotuma dental sample indicate a closer relationship with polynesians than with melanesians or american indians. in addition, the rotuma teeth are very similar to those of southeast asians. since numerous other assessments of affinity based on these same dental traits have produced expected results when evaluated with independent archaeological, linguistic, or ethnographic information (scott and turner, 1997), there is good reason to hypothesize a strong rotuma-polynesian linkage, depending, of course, on how one feels about the size of the rotuma sample. although no cultural remains were found with the rotuma bones and teeth, shutler and evrard (1991) argued that the rotuma oral traditions strongly indicated a polynesian cultural affiliation. differences between human groups are due to evolutionary processes, with genetic drift or founder’s effect figuring prominently in small groups, especially table 2. mean measures of divergence for rotuma and comparative dental samples1 rot tahi thai indo east nwc aust guam marq peru new b rot 25 30 29 23 30 29 30 27 30 27 tahi 0.000 25 25 23 25 25 25 25 25 25 thai 0.000 0.041 29 23 30 29 30 27 30 27 indo 0.000 0.071 0.000 23 29 29 29 27 29 27 east 0.007 0.000 0.015 0.045 23 23 23 23 23 23 nwc 0.057 0.223 0.223 0.135 0.303 29 30 27 30 27 aust 0.061 0.000 0.067 0.050 0.033 0.262 29 27 29 27 guam 0.074 0.130 0.065 0.050 0.100 0.313 0.097 27 30 27 marq 0.090 0.021 0.058 0.073 0.000 0.324 0.039 0.060 27 27 peru 0.138 0.307 0.347 0.275 0.270 0.093 0.452 0.450 0.452 27 new b 0.160 0.087 0.074 0.182 0.028 0.528 0.057 0.152 0.075 0.665 1whole numbers are the number of pairs of traits used to calculate the inter-group mmd values. thus, there were 25 traits involved in the mmd comparison between rotuma and tahiti, and 30 used for the rotuma-thailand mmd. mmd values are shown as fractions with small values representing greater similarity than larger values. thus, rotuma is more similar to easter (0.007) than it is with new britian (0.160). mmd values were calculated according to c.a.b. smith (berry and berry, 1967) with the modifications suggested by sjøvold (1973) and green and suchey (1976). rotuma dentition 59 for traits of little or no identifiable adaptive value, such as enamel extensions or occlusal surface characters that wear off early in life. such traits, especially if their mode of inheritance is relatively simple, should show increased inter-group frequency differences, with increased amounts of temporal separation. for example, the mmd between american indians and northeast asians is 0.154 (turner, 1986). most archaeological evidence suggests that these two geographic groups have been physically separated on the order of 12,000 to 15,000 years (fiedel, 2004; several others). the averaged mmd between rotuma and the polynesians, compared with thailand-indonesians is 0.038, about four times less that the indian-northeast asian mmd value. as time and mmd values between separated groups has been suggested as roughly proportional (turner 1986), then an mmd separation estimate between polynesians and southeast asians would be about 3,000 years. such an estimate corresponds fairly well with radiocarbon dates of about 1,000 b.c. from early tonga (shutler and shutler, 1975; bellwood, 1979) and several other excavated polynesian sites (green, 1994). pooling the same rotuma and polynesian samples and comparing their mmd values with new britain gives an averaged mmd of 0.087. this is two to three times greater that the rotuma-polynesian/southeast asian comparison and produces an estimated 8,000 to 9,000 years of separation. such a date vastly exceeds any dated archaeological site in polynesia. so, it would seem that archaeological chronometrics when linked to mega-regional dental mmd values, also leans towards a polynesian identification of this rotuma dental sample. finally, nothing more needs to be said regarding a new world origin for polynesians, other than there is no dental evidence in support of this hypothesis. this is as true today as it was more than 25 years ago when the author and g. richard scott (1977) set out to describe and assess the affinity of living easter islanders based on dental morphology. then, as now, easter and all other polynesian dental evidence points to southeast asia as the polynesian homeland, not the americas nor melanesia. finally, a word or two needs to be said about the population history of the ultimate ancestral homeland of the rotuma and other polynesian islanders. this ancestral homeland is usually considered to be in southeast asia, which is referred to as sundaland when in ice age pleistocene times sea levels were lower and all of island and mainland southeast asia were connected by dry land. the prehistoric and recent teeth of the people of sundaland possess the dental pattern previously referred to as sundadonty. recently, matsumura and hudson (2005) have challenged the local evolution hypothesis used to explain the origin of sundadonty, returning instead to the older idea of “southern mongoloids” being the result of neolithic migrants from china mixing with southeast asian australmelanesians. there are several reasons why the old migrant-mixture scenario is flawed, not the least of which is that hybridized populations sometimes do not breed true (turner, n.d.). there can be resulting offspring that exhibit the original characteristics of the parental stocks instead of the hybrid intermediacy condition. none of the samples of polynesians that i have examined exhibit a dental pattern that could be considered australmelanesian or chinese (sinodonty). despite the absence of archaeological evidence that the rotuma dental sample should be considered polynesian, oral tradition, cemetery location, island location, dating, and dental characteristics strongly suggest that it is polynesian. hence, it provides yet another polynesian isolate that supports the local evolution hypothesis for the origin of sundadonty. conclusion a small but geographically rare sample of archaeologically-derived teeth from rotuma island shares more crown and root morphological resemblances with teeth from polynesian and southeast asian dental samples than it does with teeth from the melanesian island of new britain. on the basis of these comparisons, it is concluded that this rotuma dental sample originated from a population that had a greater epigenetic relationship with polynesians than with melanesians. being relatively near the border zone between melanesia and polynesia, rotuma island may have had chronologically or geographically both melanesian and polynesian occupants; however, the sample discussed herein can easily be hypothesized as having been polynesian. dental morphology, linguistic classification, and oral traditions independently favor a polynesian affiliation for these rotuma human remains. the rotuma teeth also help reconfirm the local evolution hypothesis for the origin of sundadonty. acknowledgments data and earlier analyses on the comparative series was gathered with grants from the national geographic society, the wenner-gren foundation for anthropological research, and arizona state university faculty grant program. the following institutions housed the comparative series when studied: american museum of natural history, new york; bishop museum, honolulu; national museum of natural history, smithsonian institution, washington, d.c.; burke museum, university of washington, seattle; archaeological survey of canada, ottawa; university of british columbia, vancouver; peabody museum, harvard university, cambridge; university of arkansas, fayetteville; university of pennsylvania museum, philadelphia; university of nevada, las vegas; university of hawaii, honolulu, field museum c.g. turner ii 60 of natural history, chicago; academia sinica, taipei; san diego museum of man, san diego; simon fraser university, burnaby. data processing and entry were aided by linda nuss (watson). richard shutler kindly made the dental sample available for study. this is contribution number 33 in my peopling of the pacific basin and adjoining areas series. literature cited bellwood p. 1979. man’s conquest of the pacific: the prehistory of southeast asia and oceania. new york: oxford university press. berry ac, berry rj. 1967. epigenetic variation in the human cranium. j anatomy 101:361-379. fiedel s. 2004. the kennewick follies. j anthropol research 60:75-110. green r. 1994. changes over time: recent advances in dating human colonisation of the pacific basin area. in: sutton dg, editor. the origins of the first new zealanders. auckland, p 1-33. green r, suchey j. 1976. the use of the inverse sine transformation in the analysis of non-metrical cranial data. am j phys anthropol 45:61-68. harris ef. 1977. anthropologic and genetic aspects of the dental morphology of solomon islanders, melanesia. ph.d. dissertation, arizona state university, tempe. harris ef, turner cg ii, underwood jh. 1975. dental morphology of living yap islanders, micronesia. archaeol & phys anthropol in oceania 10:218-234. harris ef, sjøvold t. 2004. calculation of smith’s mean measure of divergence for intergroup comparisons using nonmetric data. dental anthropolology 17: 83-93. heyerdahl t. 1952. american indians in the pacific. chicago: rand mcnally. howells ww. 1973. the pacific islanders. new york: c. scribner’s sons. matsumura h, hudson mj. 2005. dental perspectives on the population history of southeast asia. am j phys anthropol 127:182-209. nichol cr. 1990. dental genetics and biological relationships of the pima indians of arizona. ph.d. dissertation, arizona state university, tempe. pietrusewsky m. 1990. craniometric variation in micronesia and the pacific: a multivariate study. in: hunter-anderson rl, editor. recent advances in micronesian archaeology. supplement 2, micronesica. mangilao: university of guam press, p 373-402. scott gr. 1973. dental morphology: a genetic study of american white families and variation in living southwest indians. ph.d. dissertation, arizona state university, tempe. scott gr and turner cg ii. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: university of cambridge press. shutler r jr. 1998. rotuma in historic and prehistoric perspective. asian profile 26:251-254. shutler r jr., evrard js. 1991. rotuma: a case of archaeology documenting the rotuman oral tradition of the first tongan landing. man and culture in oceania 7:133-137. shutler r jr., shutler me. 1975. oceanic prehistory. menlo park: cummings publishing company. sjøvold t. 1977. non-metrical divergence between skeletal populations. ossa 4:1-133. turner cg ii. 1979. sinodonty and sundadonty: a dental anthropological view of mongoloid microevolution, origin, and dispersal into the pacific basin, siberia, and the americas. in: vasilievsky rs, editor. late pleistocene and early holocene cultural connections of asia and america. novosibirsk: ussr acad sci, siberian branch, p.762-76 [russian]. turner cg ii. 1986. dentochronoloigcal separation estimates for pacific rim populations. science 232: 1140-1142. turner cg ii. 1990. origin and affinity of the people of guam: a dental anthropological assessment. in: hunter-anderson rl, editor. recent advances in micronesian archaeology. supplement 2, micronesica. mangilao: university of guam press, p 403-416. turner cg ii. n.d. dental morphology and the population history of the pacific rim and basin: commentary on hirofumi matsumura and mark j. hudson. am j phys anthropol [under review.] turner cg ii, scott gr. 1977. dentition of easter islanders. in: dahlberg aa, graber tm, editors. orofacial growth and development. the hague: mouton publishers, p 229-249. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, p 13-31. weets jd. 1996. the dental anthropology of vanuatu, eastern melanesia. m.a. thesis, anthropology, arizona state university, tempe. rotuma dentition williams and corruccini 2007.1 29 beginning in the paleolithic and continuing through the present, a pleistocene through holocene trend within the human dentition has been recognized. dental reduction, a reduction in tooth crown diameter, dramatically changed the morphology of teeth. though europe demonstrated a dramatic form of this trend between the early and late upper paleolithic, other areas expressed this change as well, including nubia where dental reduction occurred most dramatically from 12,000-10,000 b.p. and 5,300-3,000 b.p. (calcagno, 1986; hillson, 1996). dental reduction is a clear representation of morphological change seen within the fossil record, the cause of which has been debated. many scholars have attempted to explain dental reduction (armelagos et al., 1989, bailit and friedlaender, 1966; brace and mahler, 1971; calcagno, 1986, calcagno and gibson, 1988, 1991; frayer, 1977, 1978; smith 1982; smith et al., 1986; greene, 1970) without agreement. one possible explanation lies within the archaeological record. increased tool quality during the upper paleolithic reduced the masticatory demand on teeth (frayer, 1978; brace and mahler, 1971; brace, 1963). because no selective pressures existed to maintain large tooth size, reduction resulted from the probable mutation effect (pme), which suggests that, “through random mutations, the developmental processes controlled by complex genetic mechanisms will be disrupted with the final result being an incomplete or simplified structure” (brace and mahler, 1971:192). this theory became quite controversial because of its rejection of the selection-based synthetic theory of evolution, which remains the accepted mode (bailit and friedlaender, 1966). another explanation for crown size reduction also relates to changes seen within the archaeological record (calcagno and gibson, 1991), changes resulting from the relationship between crown size and complexity in two collections bridgett a. williams and robert s. corruccini* department of anthropology, southern illinois university, carbondale, il *correspondence to: robert s. corruccini, department of anthropology, southern illinois university, carbondale, il 62901-4502. e-mail : rcorrucc@siu.edu abstract many studies show human tooth crown size increases with increasing crown complexity (i.e., extra cusps, tubercles or grooves). plio-pleistocene hominid tooth size reduction has also incurred reduction in complexity, which plays into many theories that attempt to explain this well known, sustained odontometric reduction. we correlated various types of tooth complexity with measured tooth size in two collections: the widely used asu dental models (238 md and bl dimensions of 119 teeth involved in 19 post-incisor model plaques), and in newton plantation slave remains from barbados (736 dimensions of 368 teeth from ca. 100 individuals consisting of 8 post-canine types: mandibular premolars and molars, and maxillary molars). significant positive correlations show crown size and crown complexity decrease together, thus either type of data might serve to document this decline. however the degree and pattern of this positive correlation was distinct in the two samples. dental anthropology 20:29-32. positive selective pressures for small teeth. as tool use reduced the functions that were placed upon the jaw, large chewing muscles and a robust jaw forms were no longer necessary. the teeth develop cryptically as a result of genetic pressures, independent from jaw size selection. the large teeth that were adaptive previous to the tool technology revolution crowded the smaller jaws. as a result of this malocclusion, dental infection and disease emerged, causing selection for smaller teeth (calcagno and gibson, 1991). countless other theories exist which attempt to explain dental reduction, though debate still surrounds the trend. garn et al. (1966) suggest that morphologically complex (hyperodontic) tooth crowns are usually seen within larger teeth (1966). a recent study by harris tracks one such trait, carabelli cusp (2007). carabelli’s trait may sometimes be as large as the principal cusp of the crown, and harris (2007) found that the greater the expression of carabelli’s trait, the larger the overall crown size of the tooth. harris measured teeth in the living which may not reflect the trend within teeth over time in the upper paleolithic; however, others suggest that the reducing dentitions during the upper paleolithic moved toward relatively simple crown morphologies. cucina et al., (1999) and coppa et al. (1998) contrast gene flow versus in situ selection models for the italian neolithic and later stages, and coppa et al. (1999, 2007) analyze dental traits changing from the italian paleolithic through mesolithic and neolithic to almost contemporary agricultural times, 30 but the progressively hypodontic traits they use may merely signal tooth size reduction. to further investigate the trend of dental reduction, the present study analyzes several different dental traits and their effect on overall dental size. our hypothesis is that hyperodontic teeth will be larger in both breadth and width than crowns showing hypodontic traits. materials and methods two trials were organized in order to analyze dental traits. part a involved data concerning the asu dental anthropology system (turner et al., 1991). part b analyzed a dental collection from barbados on loan to the siuc anthropology department. part a the asu dental anthropology system is the primary plaster cast system for standardized grading of varying dental complexity (turner et al., 1991). this system displays 27 different dental traits in upper and lower teeth grading the increasing complexity of a given trait from 0 to 5 in most cases, with some plaques measuring up to 9 grades of complexity for a single trait (turner et al., 1991). the traits described within the asu dental anthropology system represent traits that are easily standardized for study among many different dental specimens. also, they are easily observed in teeth reducing potential for inter-observer error. of the 27 traits displayed within the system, 19 were chosen for analysis. the traits included: upper molar cusp 5, hypocone cusp 4, metacone cusp 3, parastyle, carabelli’s trait, anterior fovea lower m1, distal accessory ridge upper canine and lower canine, tuberculum dentale upper i1, bushman canine, deflecting wrinkle, protostylid, lower molar cusp 5, cusp 6, cusp 7, mid trigonid crest (lower m1), mid trigonid crest (lower m2), mesial lower premolar cusp number (“p/1” plaque, or trait 16 as described with the associated sheet), and distal lower premolar cusp number (“p/2” which is trait 17). the remaining 8 plaques which were not measured are related to shovel-shaped incisors and were excluded from the study because these traits are not clearly known to be present in dentitions prior to the upper paleolithic and do not clearly relate to increased crown complexity of the incisors. each tooth displayed on a given plaque was analyzed for standard maximum mesiodistal and buccolingual measurements. two different sets of calipers, a digital model, mitutoyo absolute digimatic and analog model mitutoyo no. 505-636 calibrated to 0.05 mm were used. the digital model was the primary set used for measurements; however the tips on this model were fairly wide and blunt (better for measuring buccolingual breadths) and could not properly mesiodistally measure some of the teeth on the plaques because of their closeness to one another. in these cases the sharpened-point analog model was used to measure the tooth. in order to ensure reliable readings for each measure, the calipers were calibrated to 0.00 before taking each measurement. both the mesiodistal and buccolingual measurements were taken at least twice for each tooth to ensure reliable measurements were being recorded. all data were entered into a spreadsheet. mesiodistal and buccolingual measurements were each entered on a separate line independent of each other in order to assess the significance that the crown complexity had on each tooth measurement independent of the other. after all of the plaques were measured, we proceeded to correlate complexity compared to tooth size measurements using a collection of teeth in an actual single population. part b the department of anthropology excavated a large collection of remains from newton plantation, barbados that pertained to slaves from the island country (corruccini and handler et al., 1982). these remains had been analyzed previously for more traditional cusp number and tooth mesiodistal and buccolingual measurements. no detailed, highly multi-state traits were analyzed from these remains, unlike the asu system. this grading system was much simpler, consisting of 3 or 2 cusped mandibular premolars, 5 or 4 cusped mandibular molars, and 4 or 3-cusped maxillary molars. as there was no variation to the 2-cusped mesial mandibular premolars, they were considered to be a 2+ (entered as 2.5) when adjacent to a canine tooth with a prominent accessory ridge or tubercle. similarly, maxillary first molars did not vary from showing the 4 basic cusps but were coded as 4.5 when clearly showing a carabelli cusp. the original data for cusp numbers and mesiodistal and buccolingual measures were already in existence for mesial and distal lower premolars and upper and lower molars 1, 2, and 3, so the teeth themselves were not measured for this particular study (corruccini et al., 1982). a total of approximately 100 individuals available in the collection were analyzed. for most individuals only the measurements and cusp number for the left tooth were used. in cases where no data existed for the left, the numbers for the right tooth were collected instead. for some individuals not all premolars and molars were present to measure, in this case all available measurements for the left (if available) and the right (if not) were taken. the measures were entered into a database in the same manner as the asu measures. results part a a total of 119 individual teeth on 19 asu plaques were measured for both mesiodistal and buccolingual b.a. williams et al. 31 dimensions, hence 238 total cases yielding 237 degrees of freedom. the overall multiple correlation between increased crown complexity and an increase in overall crown size for the 19 traits in total was 0.640 (table 1), thus over these asu plaques there is a significant multiple r between tooth size (both mesiodistal length [l] and buccolingual breadth [b]) and the combined effects of md length versus bl breadth, crown complexity, and the individual plaque. the interaction of md versus bl dimensions in fact did not contribute significantly to this; in theory either measure could be used to the exclusion of the other, and there is considerable redundancy. the contribution of heterogeneity over different plaques was quite a bit stronger than the contribution of crown complexity score, but the latter nevertheless was significantly greater than zero (f = 1.79, p < 0.02; even with the degrees of freedom halved to acknowledge the redundancy, p < 0.03). complexity-size correlations ranged above r = +0.7 for several plaques, but the sample size per plaque was technically very small. the pooled weighted correlation was r = 0.41. part b a total of 368 teeth from the newton plantation population were analyzed for buccolingual and mesiodistal dimensions. in this much larger (but probably much more redundant) sample of teeth, there was a very significant multiple r = 0.792 between size on the one hand and complexity, tooth type, and lversus-b, with the latter factor relatively small (f = 48) but significant, meaning mesiodistal and buccolingual dimensions offered a significantly large amount of independent information. the complexity contribution to the multiple r (unlike part a above) is slightly larger than the tooth type contribution and is highly significant even when drastically reducing the degrees of freedom. partial correlation (holding tooth type constant) between cusp number and size was r = +0.639. discussion thus in different ways, the two data sets indicate highly significant positive correlation between hyperodontic aspects of crown complexity and larger crown size. dental reduction is a trend that baffles many researchers. within early (pliocene) hominid history, teeth were selected to become larger in order to combat effects of attrition; however, within the paleolithic and mesolithic the dramatic change to smaller teeth contradicts the previous evolution of the dentition. to explain this trend, which is clearly seen in the fossil record, several researchers have proposed similar ideas. harris (2007) shows carabelli’s cusp has more complex expression when the overall diameter of the tooth crown becomes larger. garn et al. (1966) found that mesiodistal crown diameter is significantly related to cusp number, with larger teeth in general possessing more cusps. that human teeth became not only smaller but less complex is not inconsistent with various theories, for instance those highlighting body size, caries resistance, and pme. with the present study, attempts have been made to establish what relationship exists between crown complexity and overall mesiodistal and buccolingual diameters. results from the asu system suggest that there is indeed a positive correlation between morphologically complex teeth and large tooth size across different teeth and traits. there is admittedly some inconsistency with measurements of the asu dental system because these plaques were created with ordinal examples of crown complexity, and there was no alternative to correlating ordinal with continuous data. the newton plantation data allowed independent tracking of the correlation between crown complexity table 1. manova with tooth size (md or bl dimension in mm) as the dependent variable1 part a: asu plaques source sum squares df mean square f value p value ordinal score 81.3 21 3.87 1.79 0.021 plaque (trait) 139.2 1 139.2 64.4 0.000 md vs. bl 2.1 1 2.1 0.981 0.323 part b: newton plantation source sum squares df mean square f value p value cusp number 5155054 3 1718351. 186.0 0.000 tooth 1528223 1 1528223. 64.4 0.000 md vs. bl 450879 1 450879. 49.0 0.000 1crown dimension codes are mesiodistal (md) and buccolingual (bl). crown size and crow complexity 32 and tooth size in a relatively homogeneous population. these data repeat the positive correlation between crown complexity and larger teeth. this study does indicate a significantly strong relationship between increased crown complexity and larger teeth; however, more research should be conducted, especially with populations from the paleolithic to determine if this relationship is seen to the same extent over time within the fossil record. until contradicting evidence emerges, it may be seen as equivalently valid to measure teeth or to use nonmetric traits for genetic purposes. it is also pointed out that buccolingual tooth dimensions are much more standardized, and much more resistant to change from attrition than other traits (hill, 2004). literature cited armelagos gj, van gerven dp, goodman ah, calcagno jm. 1989. post pleistocene facial reduction, biomechanics and selection against morphologically complex teeth: a rejoinder to macchiarelli and bondioli. hum evol 4:1-7. bailit hl, friedlaender js. 1966. tooth size reduction: a hominid trend. am anthropol 68:665-672. brace cl. 1963. structural reduction in evolution. am nat 97:39-59. brace cl, mahler pe. 1971. post-pleistocene changes in the human dentition. am j phys anthropol 34:191204. calcagno jm. 1986. dental reduction in post-pleistocene nubia. am j phys anthropol 70:349-363. calcagno jm, gibson kr. 1988. human dental reduction: natural selection or the probable mutation effect. am j phys anthropol 77:505-517. calcagno jm, gibson kr. 1991. selective compromise: evolutionary trends and mechanisms in hominid tooth size. in: kelley ma, larsen cs, editor, advances in dental anthropology. new york: wiley liss. p 5976. corruccini rs, handler js, mutaw rj, lange fw. 1982. osteology of a slave burial population from barbados, west indies. am j phys anthropol 59:443-459. coppa a, cucina a, lucci m, vargiu r, mancinelli d. 2007. origins and spread of agriculture in italy: a nonmetric dental analysis. am j phys anthropol 133:918-930. coppa a, cucina a, mancinelli d, vargiu r, calcagno j. 1998. dental anthropology of central-southern iron age italy: the evidence of metric versus non-metric traits. am j phys anthropol 107:371-386. coppa a, cucina a, vargiu r, mancinelli d, lucci m. 1999. the pleistocene-holocene transition in italy: the contribution of the morphological dental traits. am j phys anthropol suppl 28:111. cucina a, lucci m, vargiu r, coppa a. 1999. dental evidence of biological affinity and life conditions of prehistoric trentino (italy) samples from the neolithic to the early bronze age. int j osteoarchaeol 6:404416. frayer dw. 1977. metric dental change in the european upper paleolithic and mesolithic. am j phys anthropol 46:109-120. frayer dw. 1978. the evolution of the dentition in upper paleolithic and mesolithic europe. lawrence: university of kansas publications in anthropology, no. 10. garn sm, lewis ab, dahlberg aa, kerewsky rs. 1966. interaction between relative molar size and relative number of cusps. j dent res 45:1240. greene dl. 1970. environmental influences on pleistocene hominid dental evolution. bioscience 20:276-279. harris ef. 2007. carabelli’s trait and tooth size of human maxillary first molars. am j phys anthropol 132:238246. hill mk. 2004. dental reduction and diet in the prehistoric ohio river valley. dent anthropology 17: 34-44. hillson s. 1996. dental anthropology. cambridge: cambridge university press. smith p. 1982. dental reduction: selection or drift? in: kurten b, editor. teeth: form, function, and evolution. new york: columbia university press, p 366-379. smith p, wax y, adler f, silberman u, heinic g. 1986. post-pleistocene changes in tooth root and jaw relationships. am j phys anthropol 70:339-348. turner ii cg, nichol cr, and scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors, advances in dental anthropology. new york: wiley & sons. p 13-31. b.a. williams et al. lease and harris 2001.2 pg 7.jpg pg 8.jpg pg 9.jpg pg 10.jpg pg 11.jpg lease 2002.4 26 27 dental morphology 1998: proceedings of the 11th international symposium on dental morphology. edited by john t. mayhall and tuomo heikkinen. oulu: oulu university press (paperback), 1999. 492 pp. isbn 951-42-5481-3. $100, including shipping. the recent volume resulting from the international symposium on dental morphology held in 1999 in oulu, finland exemplifies john mayhall’s observation that: “…dental morphology means many things to many people.” the 55 papers in this volume cover a wide range of subjects and are divided into six sections: dental anthropology, dental evolution, ontogeny, technology, morphological integration within the dental and craniofacial complex, and dental genetics. each section’s set of papers provides an interesting mixture of the latest research in a particular field. the section on “dental anthropology “ is the largest with 23 papers covering a variety of topics from traditional population comparisons (nagai and kanazawa) to development and eruption (antoine et al. and smith et al.). the paper that embodies the spirit of this section is mayhall’s. in his paper, mayhall puts forth a “plea” for dental morphology researchers to remember that in many cases non-metric traits should not be scored as “present or absent” because they exhibit a range of variation in a population. mayhall connects dental anthropology’s past research with its future with his six recommendations: 1. give complete frequencies for each identifiable variation 2. use recognized standards for recording trait variations 3. do not use presence/absence unless trait is truly dichotomous 4. indicate the ranges of variation 5. indicate the size of each category of variation 6. if results must contain combined data: a) indicate the variability within the group and subgroups b) indicate the sources of variation c) indicate the provenance of the sub-groups d) indicate the sub-group size. (mayhall 1999:46) the second section, “dental evolution,” consists of 11 papers, the majority dealing with species other than homo sapiens. topics covered include gross morphology (turnbull et al., mazza) and the development of hunterschreger bands (suzuki et al.). one of the few papers to examine homo sapiens in this section is niskanen’s, “the origin of the anatomically modern human face through differential rates of tooth size and facial size reduction,” in which two behavioral models are tested as possible explanations for the anatomically modern h. sapiens pattern. this paper is a classic example of a biocultural examination of human evolution. the seven papers in the “ontogeny” section focus mainly on the developmental aspects and morphology of enamel and dentin of several different species. harris et al.’s paper examines sexual dimorphism in the enamel and dentin thickness of human deciduous molars derived from different populations. one interesting aspect of this paper is the level of study: most studies of dental sexual dimorphism are confined to macroscopic analysis, while harris et al. examine the actual dental tissue which may cause sex differences in the dentition. while the fourth section, “technology,” is one of the smallest sections, with just four papers, it is also one of the most interesting. in each paper, a new technique for study is outlined and explained. the first and last papers present new imaging systems for dental measurements in comparison to standard techniques. the paper by smith et al. examines growth of the dej and outer enamel surface of hominid permanent and deciduous molars using c-t scans. the paper by willmot et al. examines developmental defects and post-eruptive defects in the enamel using imaging analysis. the fifth section, “morphological integration within the dental and craniofacial complex,” consists of four papers dealing with the relationships of the dentition with other anatomical structures, e.g. the cranium. other papers in this section are devoted to how the dentition is affected by biological processes, such as aging. the last and smallest section, on dental genetics, contains two papers. the first paper, by townsend, dempsey and richards, examines genetic and environmental contributions to the metrics (and one non-metric trait) of the dentition in twins. the second paper, by heikkinen et al., is an investigation of the effects of race and sex on symmetry of tooth eruption in different populations. there is no easy way to classify this volume because of its eclectic mix of subjects, but it will surely fulfill the editors’ hopes to stimulate interest in various research areas. unfortunately, since the majority of the pictures, diagrams, and charts are re-creations of slides from the presentations, the quality varies from paper to paper. overall, however, the photographs are of superior quality, and function to enhance the text. this volume will serve as an exceptional resource: it provides the reader with the latest findings and technologies in diverse areas of dental anthropology research. loren r. lease department of anthropology the ohio state university columbus, oh 43210 book reviews stefan 2006.2 70 dental morphological variation can be considered to fall within two broad categories: (1) those that involve major deviations from the basic dental blueprint and (2) those that involve minor, subtle variations in crown and/or root morphology (hillson, 1996; scott and turner, 1997). included within the first category are such dental anomalies as supernumerary teeth (polygenesis or polydontia), missing one or more teeth (agenesis or hypodontia), fusion of adjacent teeth, transposition of teeth, rotation of teeth, malposition of teeth, deviations from the “normative” crown morphology (e.g., conical lateral incisors, 3-cusped upper premolars, “mulberry” molars) and other sundry anomalies. the second category of dental variation includes minor variations in secondary cusps, fissure patterns, marginal ridges, supernumerary roots, and so forth (scott and turner, 1997:3). many of the dental anomalies in the first category involve developmental errors in the number and/or positions of individual tooth germs or tooth morphogenic fields. however, the existence of dental morphogenic fields has been debated (henderson and greene, 1975). evidence illustrating an extremely rare form of dental rotation, as well as supporting the presence of a premolar morphogenic field is discussed below. specimens within the skeletal collection of the american museum of natural history, new york, are two specimens displaying a unique rotation of a maxillary p3-p4 unit. case 1: amnh 99.1/1395 the first case consists of well-preserved maxillary and mandibular dental arches of a specimen from the *correspondence to: vincent h. stefan, department of anthropology, herbert h. lehman college, cuny, 250 bedford park blvd. west, bronx, ny 10468 e-mail: vincent.stefan@lehman.cuny.edu brief communication: rotation of the maxillary premolars: evidence in support of premolar morphogenetic field vincent h. stefan* department of anthropology, herbert h. lehman college, cuny, bronx, ny 10468 collection of marquesas island crania collected by h. l. shapiro during the templeton crocker pacific expedition in 1934 or possibly during his participation in the b. p. bishop museum tuamotu expedition in 1929. this specimen possesses a unique dental anomaly in which both the maxillary left p3 and p4 were mesially rotated 90º, as a unit (figs. 1-2). crown morphology of the premolars is completely normal. also evident in the specimen’s dentition is moderate shoveling of the central and lateral incisors, as well as a small expression of carabelli’s trait on the first maxillary molars. no other dental anomaly was noted. case 2: amnh 99/8478 the second case consists of well-preserved maxillary and mandibular dental arches of a specimen from the collection of cañon del muerto, arizona crania collected by earl h. morris during an american museum of natural history expedition in 1923 and 1924. this specimen also possesses a unique dental anomaly in which both the maxillary right p3 and p4 were distally rotated ~80º, as a unit (figs. 3-4). however, unlike the p4 of the amnh 99.1/1395 specimen, the p4 of this specimen appears to have distally rotated an additional 180º. crown morphology of the premolars is normal otherwise, though with a relatively large carious lesion on the distal surface on the p4 crown and root. also evident in the specimen’s dentition is shoveling of the central incisors, as well as the medial rotation of the central incisors. no other dental anomaly was noted. abstract: the presence of an individual tooth, axially rotated within the maxillary and/or mandibular dental arcade is not an uncommon occurrence in the human dentition. far rarer is the axial rotation of two or more adjacent teeth, rotated together as a “unit” within the dental arcade. two rare cases are presented here, each case possessing a maxillary p3-p4 unit that has been axially rotated. this event is in and of itself interesting and important, yet it also potentially provides support for the concept of a “premolar” morphogenetic field. dental anthropology 2006;19(3):70-73. 71 fig. 1. occlusal view of amnh 99.1/1395 maxillary dentition. rotated maxillary premolars fig. 2. close-up view of left maxillary premolars of amnh 99.1/1395. 72 discussion minor-to-pronounced axial rotation has been noted of individual teeth of the maxillary and mandibular dental arcade. the direction of this axial rotation can be either mesial or distal. winging and counter-winging, either unilateral or bilateral, of the maxillary central incisors, seen predominantly in native american indians, is one example of a minor rotation of a tooth (dahlberg, 1963; escobar et al., 1976). more pronounced axial rotation of an individual tooth typically involves a 90 to 180 degree rotation (lui, 1980; tay, 1968; van nievelt and smith, 1997). normally, these cases of extreme axial rotation are also characterized by either unilateral or bilateral rotation of individual teeth. however, the rare cases discussed above represent an even smaller sub-category of dental rotation, an occurrence where two adjacent teeth are rotated as a “unit” within the dental arcade. this type of dental rotation, to the author ’s knowledge, has not been documented or reported in the literature. these cases each possess a maxillary p3-p4 unit that has been either medially or distally rotated, an event in and of itself very interesting and important. yet, these examples of p3-p4 unit rotation also potentially support the concept of a premolar morphogenic field. butler (1937; 1939) presented the concept that the gradients in mammalian dentition was due to morphogenic fields. he proposed that each tooth germ in the maxilla or mandible possessed the same genetic information, which would allow any single tooth germ to develop into any type of tooth. it was only the tooth germ’s position in the maxilla or mandible that determined what type of tooth the tooth germ would ultimately develop into, directed by some field substance or morphogen (scott and turner, 1997). butler hypothesized three morphogenic fields, namely incisor, canine and molar, and variations within each field were due to “pattern genes” operating at a secondary level on different tooth germs within a morphological field (butler, 1937, 1939; scott and turner, 1997:82). butler ’s morphogenic field theory was applied to humans by dahlberg (1945). in addition to butler ’s three morphogenic dental fields, dahlberg defined a fourth, “premolar” dental field. dahlberg’s separation of premolars from the molar morphogenic field into its own field, resulting in the definition of four morphogenic dental fields, nicely corresponded to the four morphological classes of teeth present in humans. debate currently exists as to whether premolars should be distinguished as a dental field, separate from the molar field (scott and turner, 1997; suarez and williams, 1973; townsend and brown, 1981). many dental anthropologists argue that premolars are an anterior extension of the molar dental field, while others note crown and root morphology that support the existence of a distinct premolar dental field (scott and turner, 1997:84-85; wood and engleman, 1988; wood et al., 1988). scott and turner (1997:85) state, “to summarize, the evidence is equivocal regarding a separate premolar field….” these cases with their rotated maxillary p3-p4 units and perfectly formed premolar and molar crowns tentatively support the existence of a separate premolar morphogenic field, making the evidence slightly less equivocal. acknowledgements i would like to acknowledge the following individuals for their assistance and access to the skeletal material examined in this study and for their permission to photograph the specimens presented in this report: dr. ian tattersall, dr. kenneth m. mowbray, and gary sawyer, american museum of natural history, new york, new york. literature cited butler pm. 1937. studies of the mammalian dentition. i. the teeth of centetes ecaudatus and its allies. proc zool soc lond b107:103-132. butler pm. 1939. studies of the mammalian dentition. differentiation of the post-canine dentition. proc zool soc lond b109:1-36. dahlberg aa. 1945. the changing dentition of man. j am dent assoc 32:676-690. dahlberg aa. 1963. analysis of the american indian dentition. in: brothwell dr, editor. dental anthropology. london: pergamon press, p 149-178. escobar v, melnick m, conneally pm. 1976. the inheritance of bilateral rotation of maxillary central incisors. am j phys anthropol 45:109-116. henderson am, greene dl. 1975. dental field theory: an application to primate evolution. j dent res 54:344-350. hillson s. 1996. dental anthropology. new york: cambridge university press. lui jl. 1980. bilateral 180 degree rotation of maxillary second premolars: a case report. j dent 8:257-259. scott gr, turner cg. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. new york: cambridge university press. suarez bk, williams bj. 1973. dental growth fields and premolar morphology. j dent res 52:632. tay wm. 1968. rotated maxillary second premolars two cases with 180 degree rotation. br dent j 124:326. townsend gc, brown t. 1981. morphogenetic fields within the dentition. aust orthod j 7:3-12. van nievelt afh, smith kk. 1997. extreme bilateral molar rotation in o (marsupialia: didelphidae). arch oral biol 42:587-591. wood ba, engleman ca. 1988. analysis of the dental morphology of plio-pleistocene hominids. v. v. h. stefan 73 fig. 3. occlusal view of amnh 99/8478 maxillary dentition. rotated maxillary premolars fig. 4. close-up view of right maxillary premolars of amnh 99/8478. maxillary postcanine tooth morphology. journal of anatomy 161:1-35. wood ba, abbott sa, uytterschaur h. 1988. analysis of the dental morphology of plio-pleistocene hominids. iv. mandibular postcanine root morphology. j anat 156:107-139. feeney 2005.1 2 3 an investigation of ultrasound methods for the assessment of sex and age from intact human teeth robin n. m. feeney* department of anthropology, the ohio state university, columbus, ohio *correspondences to: robin n. m. feeney, department of anthropology, 244 lord hall, 124 west 17th avenue, the ohio state university, columbus, ohio 43210. e-mail:feeney.34@osu.edu abstract determining sex and age in human remains is necessary to achieve positive identification of individuals in forensic settings, and to provide data required for demographic analyses in archaeological samples. due to their denser mineralization, teeth may be better preserved than other skeletal elements, which are often fragmentary and poorly preserved. this work is the first to investigate the use of ultrasound methods to accurately, objectively, and non-destructively assess sex and estimate age of human skeletal remains from intact teeth. an ultrasound imaging system using pulse-echo technique and nominal frequency (3.5 mhz) longitudinal waves was developed for application on teeth. mechanical and acoustic properties of teeth were examined to explore their relationship with the interaction of ultrasound wave propagation. experiments were conducted to determine differences in wave propagation in teeth from individuals of different ages and sex, both permanent and deciduous. consistent differences in integral acoustic response patterns in the different teeth were found. it is concluded that pulse-echo ultrasound is a viable non-destructive technique to yield integral acoustic characteristic properties of teeth, potentially useful for assessing sex and estimating age, and resolving minimum numbers of individuals from commingled and scattered remains. information developed from this study will be significant to future research insofar as it introduces a new potential method that is nondestructive, fast, and easy to administer in situ. dental anthropology 2005;18:2-11. editor’s note: ms. feeney’s paper was awarded “first prize” for 2005 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. determining sex and age in human remains is necessary to achieve positive identification of individuals in forensic settings and to provide data required for demographic analyses in archaeological samples. due to their denser mineralization, teeth are generally better preserved than other skeletal elements, which can be fragmentary or poorly preserved. as a result, biological and forensic anthropologists are continually seeking accurate, objective, and nondestructive methods for assessing sex from dental remains. external tooth dimensions have been used to determine sex in contemporary (garn et al., 1977; margetts and brown, 1978; potter et al., 1981; garciagodoy et al., 1985; kieser et al., 1985a,b; de vito and saunders, 1990) and archaeological (lunt, 1969; ditch and rose, 1972; scuilli et al., 1977; owsley and webb, 1983; stermer beyer-olsen and alexanderson, 1995; teschler-nicola and prossinger, 1998) samples using population-specific discriminant function formulae. however, these functions are typically more descriptive, reflecting sex differentiation of the population, than robin feeney (left) receiving dahlberg award from daa president debbie guatelli-steinberg. 2 3 predictive. furthermore, interproximal attrition precludes obtaining proper measurements (teschlernicola and prossinger, 1998). moreover, the degree of human sexual dimorphism in crown size is not pronounced and actual size differences in individual teeth between sexes are small (hillson, 1996), relative to observer error. thickness of enamel and dentin from sections (moore, 1998) and radiographs (stroud et al., 1994; harris et al., 2001; zilberman and smith, 2001) of teeth also have been used to investigate sexual dimorphism. despite the larger size of male teeth, both relatively and absolutely, enamel thickness between the sexes does not differ significantly (stroud et al., 1994; moore, 1998; harris et al., 2001; zilberman and smith, 2001). the results of these studies all found males to possess relatively more dentin and pulp than females. however, measurements taken from radiographs require correction for magnification (grine et al., 2001). alternatively, sectioning teeth is destructive. additionally, despite the fact that the deciduous dentition demonstrates significant sexual dimorphism (moss and moss-salentijn, 1977; black, 1978; margetts and brown, 1978; de vito and saunders, 1990; harris, 1994) and that no reliable means of determining sex from juvenile skeletal remains exists, researchers typically have limited their studies to the permanent dentition. in estimating dental age, it is established that the calcification stages of teeth are a superior indicator of chronological age than are the eruption status of teeth or even the ossification of the skeleton (gleiser and hunt, 1955; lewis and garn, 1960). furthermore, there is a higher correlation between dental age and chronological age than there is between dental age and skeletal age (demirjian, 1978). in addition, dental mineralization appears to be well buffered, being comparatively unaffected by nutritional (garn et al., 1965a) and endocrine status (garn et al., 1965b) that impact on the tempo of an individual’s bony maturation. various other methods have been employed to estimate age from the dentition. several histological methods of age estimation for adult remains exist that examine cementum annulation layers (stott et al., 1982; wittwer-backofen et al., 2004) and secondary dentin deposits (gustafson, 1950), but these are destructive of the tooth sample. furthermore, morphological methods, including dental attrition (brothwell, 1989) and periodontal regression and root translucency (lamendin et al., 1992; prince and ubelaker, 2002), carry with them an element of subjectivity. after the completion of tooth development, it is increasingly difficult to assess age accurately (xiaohu et al., 1992). studies by philippas (1961) and philippas and applebaum (1966), on a large sample of modern permanent teeth from both sexes, found that with advancing age, irregular secondary dentin progressively fills the pulp chamber of the entire crown and root inward toward the pulp, in a natural process that occurs faster in the early years and more slowly later on, regardless of occlusal wear (attrition and abrasion). changes in the structure of teeth with age, by measuring the increase in mineral content, seem to possess potential as a nondestructive method of estimating age from teeth. the present pilot study is a first step in investigating the principles, limitations, and possibilities of using a pulse-echo ultrasound method to non-destructively, accurately, and objectively assess sex and estimate age of human skeletal remains from intact teeth. the study of mechanical and acoustic properties of enamel and dentin has been restricted to diagnostic ultrasound in the field of endodontics. the present work examines the mechanical and acoustic properties of teeth and explores their relationship with the interaction of ultrasound wave propagation. experiments were performed to determine differences in wave propagation in teeth from different ages and sex, in both permanent and deciduous teeth, with other experimental factors. a description of the design and implementation of the dental ultrasound system developed in this research is presented, along with information for future development and improvement of the system and methodology. pulse-echo technique ultrasound are high frequency sound waves above the range of audible frequencies; above 20 khz (hussey, 1975). the analysis of sound wave disturbance along its propagation path forms the basis of ultrasound testing. ultrasound wave motion creates disturbances in motion carrying energy, giving rise to wave properties, including the reflection a wave front, characteristic impedance1, attenuation, and absorption, whose behavior produce acoustic phenomena (wells, 1977). as a wave propagates from one medium to another, some of the wave energy is reflected back from the interface while the rest are transmitted through the second medium. if the ultrasound wave travels through more than two media, reflections will also occur at subsequent interfaces. the phenomenon of wave propagation in dental hard tissues is a complex interplay between the parameters of the sound wave and the characteristics of the medium. ultrastructural differences in enamel and dentin give rise to differences in mechanical properties (hardness and elastic modulus2) of these 1acoustic impedance: the opposition to the flow of sound through a surface in unit area when a wave meets the interface between two media (wells, 1977). 2elastic modulus: or young’s modulus is the resistance of a material to stress: the greater the resistance, the greater the stiffness or modulus of elasticity (wells, 1977). non-destructive sexing and aging of human teeth 4 5 tissues and result in marked difference in their sound characteristics (acoustic velocity and impedance). as a result of these differences, when ultrasound propagates from the surface of the tooth enamel into dentin, there are marked reflections at the enamel-dentin interface. figure 1 diagrams the ultrasound pulse-echo technique, showing echoes corresponding to layers along the ultrasound beam path. pulse 1 corresponds to the transducer surface, pulse 2 to the front surface of the coupling medium, pulse 3 to the tooth surface, and pulse 4 to the back surface of the coupling medium. note that the second, third, and fourth echo travel the characteristic sound density impedence medium speed (m/s-1) (kg/m3) (x106 kg s-1m-2) water 1495 1000 1.5 honey 2000 1500 3.0 glycerol 1923 1173 2.3 enamel 6000 2850 17.0 dentin 4000 2150 8.6 steel transducer 5920 7850 4.6 table 1. summary of the physical properties of acoustic media used in the experiments distance twice. as shown in figure 1, with pulse-echo ultrasound imaging different surfaces that lie one behind the other can be separated. for that reason, pulse-echo information is valuable for measuring thickness of materials, such as enamel and dentin. pulse-echo patterns can also be used to analyze material properties of a tooth that are related to its acoustic characteristic impedance (wells, 1977). if an ultrasound wave passes from a medium of higher impedance (e.g., enamel) to one with lower impedance (e.g., dentin), phase inversion (where the phase of a reflected wave is reversed) occurs at the edj. the effect of phase inversion is illustrated in figure 1 as an inverted echo at the edj, occurring after the echo that corresponds to the enamel surface. materials and methods tooth sample a sample (n = 18) of clinically extracted permanent and deciduous incisor, canine, and premolar teeth from individuals of european and continental and subcontinental indian descent was collected. the sample was chosen according to specific criteria: only those teeth that presented no or insignificant pathology (noninvasive carious lesions) and little wear were used. to avoid potentially complicated acoustic response signals, only single rooted teeth were used. actual sex and age of the individuals were known. ultrasound system components of the ultrasound system developed in this research are presented in figures 2 and 3. the data acquisition system consists of a single nominal frequency (3.5 mhz) longitudinal wave transducer, steel testing cell, a pulser/receiver cable, and an amplifier (panametrics 200 mhz computer controlled pulser/ receiver, model 5900pr). the data processing system consists of an oscilloscope with a disk data storage medium (lecroy 500 mhz oscilloscope, model 9350am), a mainframe computer, and data processing software (matlab version 12.0). the transducer (fig. 3) is a custom-made product by phoenix inspection ltd. (product number 976307). electrical pulses applied by the amplifier and passing through the pulser/receiver cable attached to the transducer will transform into sonic energy in the form of an ultrasound wave that will propagate into the target media. the ultrasound cell (fig. 3) was designed with sensor openings for the transducer to screw into. in this system, the transducer operates in a closed cell, rather than acting as a probe. in the center of the cell is the testing chamber, in which the tooth specimen is suspended during testing. the test chamber and transducer sensor tip were specially designed to accommodate the small size of human teeth in order to r.n.m. feeney fig. 1. schematic illustration of the ultrasound pulse-echo technique. the circled regions indicate phase inversion. orientation of the tooth relative to the transducer sensor beam is important because ultrasound waves will especially deviate when meeting a curved surface. accordingly, specimens were placed in the test chamber with the most flat crown surface facing the sensor tip. because only single-rooted teeth were studied, this commonl was the labial or buccal surface of the tooth. edj transducer coupling medium tooth: enamel and dentin coupling medium 21 43 2t1t 4ttime 3 dd distance d 4 5 provide a better quality signal. experimental investigations in order to achieve a superior acoustic response in teeth, additional experiments were conducted using different coupling media and specimens with different degrees of saturation. after these preliminary investigations were completed, a series of ultrasound tests were conducted on the tooth sample to obtain information on teeth from different ages and sex, in both the permanent and deciduous dentitions. tests were also performed on different teeth from the same individual to explore the ultrasonic response to natural variation in teeth. in order for the results for each type of test to be comparable, the tooth specimens were matched for similar traits, such as sex, age, tooth class (incisor; canine; premolar), tooth type (first, second, third; upper, lower), and permanent versus deciduous throughout the experiments. systematic tests disclosed no significant interand intra-observer error and disclosed significant reproducibility of the system. results and discussion dental ultrasound it is difficult to find a suitable material to couple enamel. in theory, mercury (reich et al., 1967) would be a good couplant to match the high characteristic impedance of enamel because of its fluidity and high density. however, its toxicity renders it unsafe for use and its high surface tension may lead to incomplete saturation in the presence of air-filled voids in the tooth. a coupling medium of relatively high density and high velocity was required to transfer energy from the transducer to the tooth. typically, water is used as a couplant for teeth (lees, 1968; ng et al., 1989; yang, 1991; ng, 1993). however, the characteristic impedance of water is nowhere near that of enamel or dentin (table 1), meaning that the coupling of ultrasound in dental tissues is very inefficient. this contrasts to situations involving soft tissues, where the characteristic impedance is similar to water and so energy losses are small. preliminary experiments using distilled water resulted in a very weak ultrasonic response from the tooth, confirming significant acoustic energy loss. pure honey is a high velocity and dense fluid. in theory, because its acoustic impedance is closer to enamel than water (table 1), it should couple better with the tooth, though it is viscous and has poor wetting properties. preliminary experiments found pure honey to couple very well with teeth. as far as could be determined, no other investigator has used honey as a coupling medium for teeth. glycerol, a less viscous medium than honey (table 1), was also examined and was found to have coupling characteristics comparable to honey. because honey is readily available and non-destructive sexing and aging of human teeth fig. 2. photograph of the oscilloscope, amplifier, pulser/receiver cable, and mainframe computer. fig. 3. photograph of the ultrasound testing cell and transducer. 6 7 inexpensive, it was chosen as the coupling medium. saturation of the teeth was deemed necessary to eliminate air-filled voids resulting from the decay of tissues after extraction. exclusion of air from the path of the ultrasound beam is important because air blocks the transmission of ultrasound. the effects of hydration on the acoustic properties of mineralized tissues have been previously reported (smirnow and wolfe, 1967; barber et al., 1969). the effects on the acoustic properties of teeth saturated for over 24 hours are not known. in this research, teeth were saturated in distilled water for a period of one hour and for several months. notable differences were found. teeth saturated for one hour demonstrated improved reflections compared to teeth saturated for several months. to a certain extent, the reflection qualities of a material depend on its material properties: a tooth with good structural integrity will reflect with more scatter than one of poorer structural integrity. therefore, with longer periods of saturation, the internal structures of the teeth are likely to become less distinguishable ultrasonically due to decay. this finding is of significance, as it will assist in the development of procedural methods for future dental ultrasound testing. dental tissue thickness determination in pulse-echo ultrasound, it is possible to calculate the distance (i.e., linear measurements of tissue thickness) of enamel and dentin using the echoes corresponding to the enamel surface and the enamel-dentin interface. infact, on account of sensitivity problems and poor resolution of the image, it was not possible to detect these various interfaces. however, by working backwards: if the thickness of the enamel and dentin and the time taken for sound to travel through the honey coupling fluid, enamel, and dentin are known, time differences between echoes can be calculated (appendix). this information is useful for approximating the enamel surface and the enamel-dentin junction (edj) echoes (fig. 4). ultrasound measurements were taken of the fluid filled chamber with no tooth (the reference measurement) and with a specimen present (fig. 4). the specimen was removed from the test chamber and sectioned with a microtome in the same plane that the beam passed through in the tooth during ultrasound testing. maximum thickness of enamel and dentin were measured from a photograph taken using a video microscope. using these thickness measurements of enamel and dentin and the measured distance of the honey from the transducer sensor tip to the surface of the tooth in the test chamber, the times traveled by the ultrasound pulse in enamel, dentin, and in the honey coupling fluid were calculated (appendix). with known time of flight of the ultrasonic pulse in these various media, the enamel surface and edj echoes in the time history plot (fig. 4) could be approximated. at present, accuracy determinations are not possible using the pulse-echo method developed in this research. because the ultrasonic response is integral (i.e., averaged values), it comes from different areas of the tooth, thus obscuring the reflections from the different tissue layers. a higher frequency transducer with better spatial resolution would focus ultrasound energy on a limited area of the tooth and provide better image quality, allowing more accurate determination of the various interfaces, and hence determinations of enamel and dentin thicknesses. material properties in addition to calculating distances in materials useful for measuring tissue thickness, pulse-echo ultrasound is useful for detecting differences in properties in materials (wells, 1977). on account of this, structural and compositional differences in a tooth may be detected by differences in wave propagation in enamel and dentin, which are the result of different acoustic behaviors related to the ultrastructure of these dental hard tissues. differences in wave propagation are measured in wave frequency, amplitude (sound intensity pressure), wavelength, wave speed, and energy transmission and intensity. the determination of these various measurements was not performed in this work. the sheer volume of data and specialized knowledge required to process the results make this an inappropriate method for use by anthropologists. instead, a method that offers fast and easily interpretable results by examining patterns in wave propagation was undertaken. although measured differences in wave propagation offer better scientific judgment of results, waveform plots demonstrating integral acoustic intensity at a given time and frequency window are used to detect r.n.m. feeney fig. 4. time history plot of the ultrasound response in a tooth (above) and in an empty chamber (below). 6 7 patterns of wave propagation between different teeth (figs. 5-8). the waveform plots (figs. 5-8) are based on a time-frequency dependency of reflected strength of the ultrasound field in a tooth. the reflection qualities in the ultrasound field depend, to a certain extent, on the material properties of the hard tissues of the tooth. peaks and troughs in reflection packets, represented by clusters of dark spots and illuminations, characterize the strength of the reflections. when acoustic energy is lost due to absorption (e.g., from air pockets in the tooth), very little of the signal has gone into the dental tissues, and this is represented by the dark spots in the images. in a time-frequency domain, improved reflections are represented by illuminated lines and patterns. the strength of the illuminations is characterized by a continuum of color, with lighter colors indicating higher intensity and darker colors indicating lower intensity. beginning at approximately 140 microseconds, the tail ends of the plots are characterized by significant noise from reflections in the transducer waveguide and should not be interpreted. age differences the progressive infilling of the root of a tooth with secondary dentin is correlated with age (gustafson, 1950). since the propagation of an ultrasound wave is affected by the material properties of a tooth, it is assumed that increased root dentin sclerosis in older individuals will provide different integral patterns of ultrasound wave propagation. teeth from individuals of varying ages were examined. figure 5 represents the response pattern of lower central incisor teeth from a 12 and 45 year-old and premolar teeth from a 46 and 70 year-old. in general, a trend in increased reflection intensity can be observed in the teeth from younger to older individuals, revealed by increased illuminations and very few dark spots (fig. 5). while better reflection qualities were observed in teeth from older individuals, likely due to advancing sclerosis, no obvious differences in wave propagation patterns were detected between similar teeth from individuals of different ages. new information, however, may become available with further data processing, by documenting the frequencies and times when a signal is present and performing statistical tests for pattern recognition. sex differences teeth from both sexes were examined and an apparent difference in the pattern of reflected energy intensity between the sexes was observed: a more uniform and band-like pattern was found to exist in female teeth, under 130 microseconds and in the 3-5 mhz frequency range, compared to males who exhibited a more distributed and irregular pattern in the whole of the frequency range (fig. 6). although discriminatory patterns of ultrasound wave propagation have been observed in teeth from different sexes it is difficult to determine exactly what these differences are. most likely, these patterns are attributed to larger proportions of dentin in male teeth compared to females stroud et al., 1994; moore, 1998; harris et al., 2001; zilberman and smith, 2001). because dentin is less heavily mineralized than enamel, energy is more likely to attenuate in this tissue, resulting in the distributed and irregular pattern of reflected acoustic energy found in the male teeth. a larger sample is required to determine if these sexspecific patterns are statistically significant. permanent versus deciduous teeth original tests were undertaken to investigate ultrasound wave propagation in deciduous teeth. figure 7 presents the ultrasonic response for a lower right non-destructive sexing and aging of human teeth fig. 5. comparison of teeth from different aged individuals. fig. 6. comparison of premolar teeth between different sexes. 8 9 deciduous canine and a lower left lateral deciduous incisor, compared with two permanent teeth of the same type, respectively. the distribution of acoustic energy arriving in microseconds and at frequencies in megahertz is markedly different between permanent and deciduous teeth. the deciduous teeth demonstrate a more uniform distribution of acoustic energy than permanent teeth, particularly below 90 microseconds and in the frequency range of 2-5.5 mhz (fig. 7). this observed pattern in deciduous teeth, compared to their permanent counterparts, is attributed to differences in their dynamic properties. apart from the paper by mahoney and associates (2000) who determined that hardness and modulus of elasticity in deciduous enamel and dentin are within the range reported for permanent teeth, research on the mechanical and acoustic properties of deciduous teeth is lacking. consequently, only speculations about the source of the wave propagation pattern observed in deciduous teeth (fig. 7) can be made. for example, it is possible that because enamel in deciduous teeth is much thinner than in permanent teeth, the teeth are overall less hard, allowing for better coupling with the fluid medium, resulting in more energy being absorbed in the timefrequency window noted above. the acoustic response pattern in deciduous teeth (fig. 7) is notably similar to the patterns found in female teeth (fig. 6), which display a uniform and clustered pattern of reflected energy in a high frequency range. it is possible that the ultrasonic response revealed in the deciduous specimens (fig. 7) is attributed to the sex of these teeth: they are from females. further investigation using a larger sample of deciduous teeth, however, is needed to confirm whether a unique pattern exists for deciduous teeth or whether the patterning is the result of other variables, such as sex. natural variation in teeth four deciduous canine teeth from the same individual were tested to investigate whether differences in natural variation in teeth could be detected ultrasonically (fig. 8). despite the difference in the reflected strength of the ultrasound field in the lower right specimen (due to an inconsistent saturation time) compared to the other three specimens (fig. 8), the integral acoustic characteristic patterns were found to be remarkably similar. the most important finding in this experiment was that canine teeth from the same individual presented very similar patterns in the characteristic response of the ultrasound field. further testing on a larger sample and improved data processing methods are required to determine if this finding is significant. if so, it may be possible, using the ultrasound method developed in this research, to discriminate between different individuals in commingled or scattered remains from their acoustic response patterns. furthermore, it would be valuable to compare whether identical teeth from different individuals have different energy reflection patterns to test if the pattern in unique to individuals or to tooth class. this information may be of additional use in discriminating between individuals in mixed contexts. limitations and future directions the sample (n = 18) is notably small and the discriminatory effectiveness of the results is questionable. although sample size was modest, the study provided insight into the possible applications and intricacies of using pulse-echo ultrasound methods for anthropological study of teeth. the values of acoustic impedance of the steel transducer, the honey couplant, and enamel and dentin are all very different (table 1). this impedance mismatch results in great loss of ultrasound energy at the interface r.n.m. feeney fig. 7. comparison between permanent and deciduous incisor and canine teeth. fig. 8. variation within canine teeth from the same individual. 8 9 between these media. in terms of acoustic impedance, a couplant more similar to enamel than honey would be preferred. yet a material of such high acoustic impedance would most likely have to be a solid. the nearest match to enamel is aluminum. however, there are problems associated with using a solid coupling agent. a solid metal couplant would produce noise in the form of multiple reflections that would overshadow the echoes from the interfaces under study. furthermore, it is difficult to physically adapt a solid to the curved surface of a tooth without taking invasive measures (e.g., lees and barber, 1968; barber et al., 1969), which would negate the non-destructive nature of ultrasound testing and damage the valuable tooth. one possible solution would be to use a gel contained inside a thin, soft membrane glued to the transducer, as was tried by spranger (1971) and fukukita et al. (1985), which appeared to adapt well to oral tissue. apart from the considerable mismatch between the steel transducer and enamel, honey is otherwise a good couplant because it is biocompatible, readily available, and inexpensive. the resolution of the ultrasound system is mainly dependent on the transducer characteristics. in the works by yang (1991) and ng (1993), the echo from the enamel-dentin interface was only observed on some portions of the tooth surface. often, some areas of the tooth surface are rough or ridged and the enamel surfaces may not have been formed in parallel or in near parallel with the edj. these factors make the detection of the enamel-dentin interface difficult. to resolve this, a higher frequency transducer than 14.5 mhz and 18 mhz, used by yang (1991) and ng (1993), respectively, should be used. resolution problems experienced in this research may be resolved with the use of a single focused high frequency transducer. a focused high frequency transducer would offer high resolution by achieving good lateral resolution, which would enable better imaging of the curved surfaces and accommodate variation in teeth. of additional importance is the execution of testing and data processing. in contrast to the mounting, sectioning, and microscopic procedures normally required to obtain information about sex and age from dental remains, the operation of the ultrasound system developed in this research is both quick and straightforward. moreover, the compact size and relatively light weight of the ultrasound testing cell and oscilloscope with data storage medium renders this system ideal for administering tests in situ, rather than in a specialized laboratory. the methods for processing the data are, however, protracted. at present, specialized knowledge of software designed to process ultrasound data and to transform it into interpretable plots is essential, as is experience interpreting the results. however, the dental ultrasound system is in the pilot stage of development. with further work, more simplified software can be developed for straightforward use and simple interpretation for use by non-specialists. apparent differences in integral acoustic characteristic patterned responses were observed in different types of teeth in these experiments. further processing of data, such as documenting the frequencies and times when a signal is present and performing statistical tests for pattern recognition to find significant patterns, may offer further information on which to base interpretations. additionally, the development of a prediction model for wave propagation in teeth (e.g., ghorayeb et al., 1998; ghorayeb, 2001) may further facilitate interpretations. nevertheless, although the results do not provide a statistical basis for definitive judgment, consistent differences have been observed in the patterns of the time of arrival of the ultrasound energy in microseconds and in frequencies at megahertz in teeth, particularly in teeth from different sexes, deciduous teeth, and in identical types of teeth from the same individual. summary and conclusions this paper describes original work conducted on the use of pulse-echo ultrasound as a means of nondestructively assessing sex and estimating age in skeletal remains from intact teeth. the most important findings presented are: (1) non-destructive ultrasound imaging of intact human teeth, (2) non-destructive means of measuring intact enamel and dentin tissue thickness, (3) detection of consistent acoustic integral response patterns for different types of teeth, and (4) development of the understanding of how dental anisotropic materials and natural variation affect ultrasound wave propagation. investigation of these endeavors in this research has provided additional information valuable for the future development of instrumentation and methodology for non-destructive ultrasound imaging of teeth. the dental ultrasound system has a number of feasible applications, even in its present state of development, but the accuracy of the ultrasound system and the smallest change that it can detect need to be determined. furthermore, the development of software to assess for statistically significant patterns is required to eliminate subjectivity. ultrasound could be applied to the study of teeth if a thorough understanding of wave propagation in teeth were available. the difficulties are caused by the physical situation of the teeth, compounded by high-resolution requirements. the principal problems experienced in this research were: (1) small physical size of teeth, (2) complex structure and gradients in mechanical properties of teeth, (3) irregular shape of the teeth characterized by complex surface morphology, and (4) difficulty transmitting sound waves through the tooth. although the dental ultrasound system non-destructive sexing and aging of human teeth 10 11 developed in this research is not accurate enough at present to be of practical use, the results that have been obtained are encouraging. there exists a great deal of room for improvement of the system and ultrasound remains a promising method to tackle the problem of non-destructive study of teeth. from the abbreviated discussion of ultrasonics in this work it appears likely that significant possibilities, such as determining sex and age of remains from teeth ultrasonically, lie in the development of the instruments capable of providing precise and quantitative measurements. acknowledgments my gratitude is extended to drs. robert pastor (archaeological sciences), kirill horoshenkov (civil and environmental engineering), and elaine brown (polymer science engineering) at the university of bradford, uk, for their valuable assistance and for providing access to necessary equipment and facilities. in addition, i would like to thank the dental surgeons at the manningham lane dental center and mark edwards dental practice (west yorkshire, uk) for providing 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rm, zerilli a. 1992. a simple technique for age estimation in adult corpses: the two criteria dental method. j forensic sci 37:13731379. lees s. 1968. specific acoustic impedance of enamel and dentin. arch oral biol 13:1491-1500. lees s, barber fe. 1968. looking into teeth with ultrasound. science 161:477-478. lewis ab, garn sm. 1960. the relationship between tooth formation and other maturation factors. angle orthod 30:70-77. lunt d. 1969. an odontometric study of medieval danes. acta odontol scand [supplement 55] 27:1-173. mahoney e, holt a, swain m, kilpatrick n. 2000. the hardness and modulus of elasticity of primary molar teeth: an ultra-micro-indentation study. j dent 28: 589-594. margetts b, brown t. 1978. crown diameters of the 10 11non-destructive sexing and aging of human teeth deciduous teeth in australian aboriginals. am j phys anthropol 48:493-502. moore ee. 1998. sexual dimorphism in enamel thickness in the human mandibular canine. unpublished master’s thesis. tennessee: 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criterion in forensic dentistry. j dent res 61:814-817. stroud jl, buschang ph, goaz pw. 1994. sexual dimorphism in mesiodistal dentin and enamel thickness. dentomaxillofac rad 23:169-171. teschler-nicola m, prossinger h. 1998. sex determination using tooth dimensions. in: alt kw, rosing fw, teschler-nicola m, editors, dental anthropology: fundamentals, limits, and prospects. new york: springer-verlangwien, p 480-500. wells pnt. 1977. biomedical ultrasonics. london: academic press. wittwer-backofen u, gampe j, vaupel jw. 2004. tooth cementum annulation for age estimation: results from a large known-age validation study. am j phys anthropol 123:119-129. xiaohu x, philipsen hp, jablonski ng, pang km, jiazhen z. 1992. age estimation from the structure of adult human teeth: review of the literature. forensic sci int 54:23-28. yang zz. 1991. ultrasound surface imaging and the measurement of tooth enamel thickness. unpublished phd dissertation. manchester: university of manchester institute of science and technology. zilberman u, smith p. 2001. sex and age-related differences in primary and secondary dentin formation. adv dent res 15:42-45. appendix calculating distances from ultrasound measurements: 1) scale: 1 mm = 18 mm on video microscope photograph 2) sound speed (c) in m/s-1: enamel: 6000 dentin: 4000 honey coupling fluid: 2000 3) maximum thickness measurements: enamel: 17 mm on video microscope photograph = 17/18 x 1 mm = 0.94 mm dentin: 34 mm on video microscope photograph = 34/18 x 1 mm = 1.89 mm honey: 4 mm from transducer sensor tip to front surface of tooth in chamber 4) time travelled (t): t = dc, where d = distance; c = sound speed: enamel: 0.94 x 10-3 x 6000 = 5.64 µsec (x 2 for return pulse = 16 µsec) dentin: 1.89 x 10-3 x 4000 = 7.56 µsec (x 2 for return pulse = 15.12 µsec) honey coupling fluid: 4 x 10-3 x 2000 = 8 µsec (x 2 for return pulse = 16 µsec) 34 35 dental morphology 2001: proceedings of the 11th international symposium on dental morphology. edited by alan brook. sheffield: sheffield academic press ltd. (hardback), 2001. 350 pp. isbn 1-84127-289-2. a symposium provides an arena for scientists to forge new syntheses based on their most recent research findings and methodologies. unfortunately, the reality of most published symposium proceedings is that the information is no longer cutting edge once the papers are published one (to two) years later. the organizers of the 12th international symposium on dental morphology attempted to address this problem by publishing the peer-reviewed papers in dental morphology 2001 at the time of the symposium. however, because only those papers submitted well in advance of the conference could be included in dental morphology 2001, many of the papers presented at the symposium were left out of the volume. consequently, the resulting volume is timely, but incomplete. as with the past symposium publications, the volume is divided into six sections consisting of: dental anthropology, dental evolution, ontogeny, technology, morphological integration within the dental and craniofacial complex, and dental genetics. in comparison to the previous volume, dental anthropology 1998, there are substantially fewer papers included in each section. in the present volume, seven papers comprise the dental evolution section. the dental anthropology portion of the book is the second largest with six papers. three subjects, ontogeny, technology, and dental genetics, have four articles each. finally, the morphological integration within the dental and craniofacial complex segment has five papers. by contrast, in the previous volume, dental anthropology had 23 papers, dental evolution consisted of 11, ontogeny was comprised of seven papers, technology had four, and morphological integration within the dental and craniofacial complex had seven papers. the dental genetics section was the only section to increase in number, from two to four papers, from the earlier volume to the present one. the scope and depth of the papers also seem to be diminished in comparison to the previous volumes of the series, and again, this may be the result of the early publication deadline. several papers seem to be overviews of the research performed or pilot studies for further research. on the other hand, while the volume does not have the complete proceedings of the symposium, several articles are of note. p. m. butler ’s “what happened to the field theory” provides a unique opportunity to appreciate the background and logic behind one of the earliest and most significant theories in dental anthropology. in this article, butler traces the influence of experimental work in the induction of limbs in urodele larvae on his speculations regarding the development of the dentition evolving as part of an integrated system across the mammalian order (p.4). the field theory has influenced numerous research endeavors, such as aa dahlberg’s study dental morphological variation in human populations, experimental histology work on the enamel organs, and osborne’s clone theory. butler notes that while there have been great advances in the field of dental anthropology over the last 60 years, fundamental questions, such as what determines the distribution of cusps between teeth and among species, remain unanswered. other articles of note include ef harris’s contribution, “deciduous tooth size distributions in recent humans: a world-wide survey.” previous comparative studies conducted in this manner have been performed primarily on the permanent dentition. this overview is one of the first comparative studies performed strictly on the deciduous dentition in recent human populations. besides providing a forum for research and comparative studies, the symposium also introduced various methodology papers. brook et al.’s article, “the development of a new index to measure enamel defects” proposed the basis for a new enamel defects index for common usage. the pilot study of the index showed promising results for a quick and straightforward method for data collection, and is being further developed. kelley and co-researchers expanded the information regarding the reconstruction of primate species’ life histories in “molar growth in the late miocene hominoid, dryopithecus laietanus.” in this paper, the authors discuss the life history of a miocene hominoid using comparative data on first molar development in other extinct and extant primates. the physical format of the book was a bit awkward. unlike the previous volume, there are no color images in the 2001 volume and the majority of the tables, graphs, and images follow the papers. as a result, it is some times necessary to hunt for a particular figure or image, which can be distracting. accompanying the volume is a cd of the papers in pdf format. while the papers themselves and their associated graphs and photos are clear, the format of the file is cumbersome to use. each page is bookmarked, rather than each paper, within a section. in order to find particular papers out of order, the reader must scroll back to the table of contents constantly. on computers with slower speeds, this can be a frustrating exercise. overall, while the organizers of the symposium tackle the issue of data relevancy by the early publishing of the proceedings, the result, unfortunately, is an unfinished record of the presented papers. regrettably, this volume is not on a par with the previous editions of the series, such as the 1978 volume development, function and evolution of teeth and the 1982 volume teeth: form, book review continued on page 36. col 2. 36 function and evolution. while the reviewer can appreciate the need for timeliness, the volume could have been improved through the inclusion of the additional papers presented and by employing a more user-friendly cd format. as problems associated with the early publication of the volume are smoothed out, future volumes of the dental anthropology series will return to the high standards of the past. loren r. lease southwest foundation for biomedical research changing of the guard the american journal of physical anthropology has about a score of associate editors who facilitate the anonymous peer review process. these people are listed on the inside of the front cover of the ajpa. each handles the papers submitted to the journal specific to his or her topical area of expertise. terms run for four years, and the outgoing associate editor for matters dental, edward harris, has recently been replaced by dr. john r. lukacs (photo above) at the university of oregon. john took over from edward this april at the meeting of the editorial group at the aapa meetings in tampa. john is a founding member of the dental anthropology associaton. dr. paul r. sciulli (the ohio state university), also a founding member of the daa, served in this editorial role before edward. among the associate editor’s duties are to suggest appropriate reviewers to the editorin-chief, clark spencer larsen (the ohio state university), collect these reviews and provide clark with a summary review and suggested disposition for the article. normally, the whole review process occurs electronically using a web-based program supplied by wiley-liss. the work load varies with the seasons (and when authors get to do some writing during the academic year), but there always is plenty to do. the daa wishes john the best as he takes on these numerous duties in addition to his normal work load. the editor wetherell et al. 2004.3 18 19 this case highlights the fact that asymmetries in dental crown form, whether they be fluctuating or directional, need to be viewed as resulting from a continuum of developmental disturbances that may range from minor to severe. as our knowledge of the molecular basis of dental development continues to grow, we should eventually be able to explain in cellular and molecular terms the specific causes of the whole range of asymmetrical expressions in dental crown form that we observe within the human dentition. the phenotypic appearance of newly-emerged dental crowns results from an interplay between an individual’s genotype and environmental influences operating during the period of odontogenesis. environmental factors may also alter crown appearance after teeth emerge into the oral cavity, for example due to trauma, caries or wear. however, careful examination of teeth intra-orally or indirectly via dental models will normally enable the examiner to distinguish between those crown variations that have occurred during development compared with those that have resulted after emergence. it is generally assumed that the genetic influences operating on antimeric tooth pairs are identical so, in the absence of post-emergence effects, differences in crown morphology between corresponding teeth on opposite sides of the dental arch can be considered to reflect the influence of developmental disturbances during odontogenesis. these disturbances may vary in their timing, duration and severity. asymmetry in dental crown size is referred to as being directional if there is a tendency for dimensions on one side to be consistently larger than those of their corresponding antimeres. there is some evidence of directionality in deciduous and permanent crown size in relatively large human samples that exclude individuals with major developmental disorders (harris, 1992; townsend et al., 1999). however, whether these findings reflect real underlying biological influences or represent chance effects remains unclear. there also are various pathological conditions that may lead to directional asymmetries in dental crown size and shape. for example, in hemifacial microsomia—a developmental abnormality affecting the first and second branchial arches—the posterior teeth are smaller than normal, with the reduction in size being most marked on the affected side (seow et al., 1998). this is an example of directional asymmetry where the affected teeth are smaller on the affected side. fluctuating dental asymmetry refers to the small random differences in crown size or morphology commonly observed between antimeric tooth pairs. these differences may be due, for example, to differences in blood supply or space availability between sides. more severe space constraints leading to distortion of developing tooth germs may result in compression of a tooth or teeth on one side producing more marked asymmetry in size and/or shape. the magnitude of fluctuating dental asymmetry is increased in laboratory animals exposed to external stressors during development (siegel et al., 1977) and in certain human chromosomal disorders, for example down syndrome, where the aneuploidy is thought to disrupt homeostasis, leading to increased developmental instability (townsend, 1983). a similar explanation has been put forward to account for increased fluctuating asymmetry in crown size noted in individuals with localized asymmetry in human dental crown form— an interesting case john wetherell, tracey winning and grant townsend* dental school, the university of adelaide, south australia 5005 abstract. a case of a 20-year-old female is described in which the premolars and molars on the right side of the arch display altered crown proportions and altered occlusal morphology. there is no evidence of an orofacial congenital disorder or history of trauma. it is argued that the asymmetrical expression of crown form does not fall within the normal range of variation but has resulted from a localized disruption in cellular function within the developing tooth germs, probably upsetting the folding of the internal enamel epithelia. this has produced crowns that have rounded cuspal outlines and reduced intercuspal distances. superimposed space constraints in the mandible may have also led to compression of the lower molar crowns mesiodistally and affected their root formation. dental anthropology 2004;17(1):18-23. editor’s note: it is hoped that this case report will stimulate some productive discussion in the journal. please submit comments to the editor. *address for correspondence: grant townsend, dental school, the university of adelaide, south australia 5005 email: grant.townsend@adelaide.edu.au mailto:grant.townsend@adelaide.edu.au 18 19 sex chromosomal aneuploidies (townsend et al., 1986) and in individuals with cleft lip and palate (narayanan et al., 1999). of considerable interest is the report of increased directional asymmetry in the occlusal morphology of permanent first molars in 45,x/46,x mosaics (pirttiniemi et al., 1998). this study indicates that different cell lines regulated by different genes may be responsible for differences in crown form on opposite sides of the dental arches. in this paper we report on an interesting example of dental asymmetry that is evident in the maxillary and mandibular posterior segments of the permanent dentition of a young woman who has no history or signs of orofacial trauma or a congenital disorder. this case provides a good opportunity to ponder on how factors that have presumably operated unilaterally on the developing dental arches can lead to marked asymmetries in final crown forms in an otherwise healthy person. case report figures 1 and 2 show occlusal views of the maxillary and mandibular dental arches of a 20-year-old female of european ancestry who presented at the adelaide dental school in 2001 for a routine dental check-up. the woman had no history of any major medical problems, nor was there any history of her mother suffering illhealth during pregnancy. she had chicken pox as an 8-9 year-old but did not take any medication at that time. there was also no history or evidence of visible facial asymmetry. in both arches, the first premolars had been extracted previously for orthodontic reasons, and the third molars had not emerged in the maxilla. the woman had also worn an upper removable orthodontic appliance for seven months in 1995. a supernumerary tooth had been extracted from the maxillary right molar region distal to the first molar prior to the commencement of orthodontic treatment. the maxillary right third molar was not present and the woman confirmed that it had not been extracted. the mandibular left third molar was partly erupted. the maxillary left first and second molars and mandibular left first molar had fissure sealants placed on their surfaces in 2001 and the occlusal surface of the maxillary right first molar had been restored in amalgam in 1994, then the amalgam had been replaced with composite resin in 2001. the crowns of the maxillary right second premolar and the first and second molars were markedly different in form to those on the left. there was also some minor variation in crown form of the maxillary right canine. the mandibular right second premolar and first, second and third molars all showed different and unusual crown form compared with those on the left. the affected maxillary and mandibular premolar and molar teeth showed similar features, with altered crown shapes and rounded forms with small intercuspal distances. the maxillary right canine crown showed increased labial convexity compared with its antimere, but this variation was less marked than those of the premolars and molars. intraoral examination did not disclose any hypoplasia or hypocalcification of the enamel of affected teeth. examination of a panoramic radiograph obtained at 20 years 5 months of age showed that the maxillary right third molar was congenitally missing (fig. 3). this film disclosed some differences in the root morphology of the mandibular right first and second molars compared with the corresponding teeth on the left. the roots of the mandibular right first molar appeared to be more slender than those of the mandibular left first molar. the roots of the mandibular right second molar were more curved (like plier handles) than those of its antimere. the buccal roots of the maxillary right molars also appeared to converge more than the corresponding molar roots on the left that displayed a distal curve. the roots of all teeth were fully formed, except for the mandibular left third molar that was distally impacted. fig. 2. occlusal view of the mandibular dentition of the woman. fig. 1. occlusal view of the maxillary dentition of the woman. localized asymmetry in the permanent dentition 20 21 bitewing radiographs were also available that enabled an assessment of enamel and dentine thickness and pulp cavity anatomy. the altered contours of the proximal surfaces of affected teeth made it difficult to locate homologous points on the mesial and distal surfaces of antimeric teeth. however, using the methods described by stroud et al. (1994) and comparing the woman’s data with the standards provided by stroud and colleagues, enamel and dentine thickness fell within the normal ranges and there were only minor differences between the sides. the sizes of the dental crowns were compared between sides and with normal data published for individuals of european ancestry (townsend et al., 1986). maximum mesiodistal and buccolingual crown diameters were recorded according to the definitions of seipel (1946) and expressed as z-scores against standards for girls. all of the z-scores except two were positive, indicating that the woman’s dental crown size was generally larger than normal. in particular, the z-score for the buccolingual crown diameter of the maxillary right second premolar was 3.5 (compared with 2.8 on the left) and the z-score for the buccolingual crown diameter of the mandibular right first molar was 3.4 (compared with 1.9 on the left). in contrast, the z-score for the mesiodistal crown diameter of the mandibular right first molar was -0.3 (compared with 1.7 on the left) and the z-score for the mesiodistal crown diameter of the mandibular right second molar was 0.1 (compared with 1.0 on the left). therefore, the mandibular right molars showed markedly reduced mesiodistal crown diameters but increased buccolingual diameters compared with their antimeres. intercuspal distances were also recorded for the woman’s first molars and maxillary second premolars, then comparisons were made between sides and with unpublished normal values that had been computed previously in our laboratory for a sample of females of european ancestry. the woman’s intercuspal distances were expressed as z-scores and all of these values were positive on the left side, consistent with the fact that overall crown size of these teeth was also larger than average. however, the values of z-scores for intercuspal dimensions of the right first molars and the maxillary right second premolar were all negative. they ranged from -0.8 for the distance between the mesiobuccal and distobuccal cusps of the mandibular first molar, to -2.0 for the distance between the mesiobuccal and mesiolingual cusps of the maxillary first molar. these measurements confirmed the visual impression that the cusp tips were closer together on the posterior teeth on the right compared with the left. the mandibular right first molar was a four-cusped tooth compared with its antimere that displayed the typical five-cusped appearance. there was also altered expression of carabelli trait between the maxillary right and left first molars, the former displaying a groove form of the feature whereas the latter showed a cuspal fig. 3. panoramic radiograph of the woman. j. wetherell et al. 20 21localized asymmetry in the permanent dentition form. when the dental casts were examined from the buccal view with the teeth in maximum intercuspation, the premolars and first molars on the right did not occlude whereas there was contact between opposing teeth on the left (figs. 4 and 5). the maxillary right canine was in a crossbite relationship with the mandibular right canine and lateral incisor. the central incisors displayed a normal overbite and overjet relationship (fig. 6), although the mandibular incisors were retroclined and the mandibular arch midline was displaced 2-3 mm to the right. given that orthodontic treatment had been carried out, including extraction of first premolars, we did not attempt to develop a common hypothesis to explain the altered crown form of the premolars and molars, and the posterior open bite, on the right side. discussion although some of the woman’s teeth showed asymmetry in overall crown size, especially the mandibular first molars, the most striking feature was the asymmetrical expression of crown shape of both maxillary and mandibular posterior teeth. the posterior teeth on the right showed more rounded cuspal outlines with smaller intercuspal distances than their antimeres on the left. the alteration in crown form was localized mainly to the maxillary and mandibular posterior segments, specifically the premolars and molars, although there was some minor variation in the labial convexity of the maxillary right canine. the first premolars had been extracted for orthodontic reasons so it was not possible to examine them. nor was it possible to examine any of the woman’s primary teeth. given that there was no indication that the enamel on the affected teeth was hypoplastic or hypocalcified, it would seem that some disturbance must have affected the morphogenesis of the developing premolar and molar tooth germs on the right side only. the location of the cusp tips on premolars and molars is associated with the development of enamel knots in the enamel organ, that is those regions of the internal enamel epithelium that cease mitosis, leading to the buckling of its surface (thesleff et al., 2001). the final shape of the cusps depends on the subsequent deposition of enamel by ameloblasts. as the woman’s enamel was apparently normal both qualitatively and quantitatively, the most likely site of the disruption is the internal enamel epithelium. we have reported that heritability estimates for intercuspal distances of molar teeth derived from a large sample of twins are only moderate in magnitude compared with those for overall crown dimensions (townsend et al., 2003). intercuspal distances were also associated with higher coefficients of variation than overall crown measures, confirming that they display relatively greater phenotypic variation than maximum mesiodistal and buccolingual diameters. these results are consistent with the findings of molecular studies (e.g., tucker and sharpe, 1999; thesleff et al., 2001), indicating that epigenetic influences related to the release of specific signalling molecules from the regions of the enamel knots are important in determining how the internal enamel epithelium folds during odontogenesis. it is possible, therefore, that the localized alteration of crown form in this case has resulted from a disruption to the development of enamel knots on one side of the arch. this may have been triggered by traumatic event. it is difficult to say what the cellular or molecular basis of such a disturbance could be, but it is tempting to suggest that an upset to neural crest cell migration, or to the reciprocal interaction between the ectomesenchymal cells of the dental papilla and the epithelial cells of the internal enamel epithelium, might underlie the problem. it is very unlikely that a genetic mutation has caused the morphological asymmetry, as this would be most likely to affect teeth on both sides of both dentitions. a posfig. 5. left buccal view of the woman’s dentition, with models occluded in intercuspal occlusion. fig. 4. right buccal view of the woman’s dentition, with models occluded in intercuspal occlusion. fig. 6. labial view of the woman’s dentition, with models occluded in intercuspal occlusion. 22 23 sible exception could be mosaicism, with different cell lines regulated by discrete genes producing morphological asymmetry. although the woman reported here showed no other signs of physical abnormality, we were unable to test for mosaicism. the observed pattern of morphological variation within the human dentition usually follows butler’s field theory (dahlberg, 1945; butler, 2001), with the more distal tooth in each class showing greater variation than more mesially positioned teeth. for example, third molars generally show considerable variation in morphology, much more than first molars. in this case, however, the “key” molar tooth seemed to be affected to the same degree as the more distal members of the class. this tends to confirm that the localized variation in crown form resulted from a distinct, though relatively minor, developmental disturbance and does not merely represent an extreme example of the normal range of development. another model that may prove useful in trying to decipher the underlying basis of variation within the human dentition is the so-called “facial homeobox code” described by sharpe (1995). the homeobox genes in the developing face are restricted to specific domains, with incisor, canine and molar fields being described. as sharpe (1995) points out, it is possible that neural crest cells are pre-patterned with homeobox genes prior to or during their migration. subsequent reciprocal interactions between those neural crest cells contributing to the ectomesenchyme of the dental papilla with the epithelial cells of the internal enamel organ would then define tooth type and shape. it is possible that some localized upset to expression of the molar homeobox code has produced the unilateral variation in dental morphology that we have observed in this case. the timing of onset and duration of crown formation of the affected teeth provide further insights into the possible nature of the disturbance. the crowns of the permanent first molars begin to calcify at around birth, so the period of folding of the internal enamel epithelium is mainly a pre-natal event, although distortion could still occur post-natally until the cusp tips have been united by the spread of calcification. the second premolar crowns commence their calcification at around 2.0 to 2.5 years and the second molars around 2.5 to 3.0 years, so folding and potential distortion of the internal enamel epithelia of these teeth persists into the post-natal period. the third molars may not commence crown calcification until 7-10 years, so there are several years after birth during which disturbances may affect their crown form (hillson, 1996:123). given that all of the affected teeth in this case show similar alterations in their crown form, it would seem that some ongoing localized disturbance in the function of one or more cell lines in the developing teeth is the most likely etiological factor. it is possible that there could have also been superimposed local space constraints that led to the alterations in overall crown shape of the mandibular molars, compressing them mesiodistally but allowing them to grow buccolingually. for example, taylor (1978:257) has described in detail the appearance of compressed teeth and suggested that their appearance may have resulted from crowding of tooth buds prior to calcification. space constraints may also account for the apparent differences in molar root form between the sides. several researchers have reported on asymmetrical expression of so-called non-metric crown variants, such as carabelli trait (e.g., saunders and mayhall, 1982; pinkerton et al., 1999). this normal variation may take the form of a large cusp on one side and a smaller cusp on the other, or there may be different expressions of grooves on each side. however, it is rare to find a cuspal form of carabelli trait on one side but no expression or a small groove on the other. again, then, the observed expression of carabelli trait in this case suggests that a specific disturbance has occurred and that the variation in expression does not fall within the so-called normal range of variation. this case highlights the fact that asymmetries in dental crown form, whether they be fluctuating or directional, need to be viewed as resulting from a continuum of developmental disturbances that may range from minor to severe. as our knowledge of the molecular basis of dental development continues to grow, we should eventually be able to explain in cellular and molecular terms the specific causes of the whole range of asymmetrical expressions in dental crown form that we observe within the human dentition. literature cited butler pm. 2001. what happened to the field theory. in: brook a, editor. dental morphology 2001. sheffield: sheffield academic press, p 3-12. dahlberg aa. 1945. the changing dentition of man. am j dent assoc 32:676-690. harris ef. 1992. laterality in human odontometrics: analysis of a contemporary american white series. in: lukacs jr, editor. culture, ecology and dental anthropology. delhi, kamla-raj, p 157-170. hillson s. 1996. dental anthropology. cambridge: cambridge university press, p 123. moorrees cfa, thomsen so, jensen e, yen pkj. 1957. mesiodistal crown diameters of human permanent teeth in individuals. j dent res 36:39-47. narayanan a, smith s, townsend g. 1999. dental crown size in individuals with cleft lip and palate. perspect hum biol 4:61-70. pinkerton s, townsend g, richards l, schwerdt w, dempsey p. 1999. expression of carabelli trait in both dentitions of australian twins. perspec hum biol 4:19-28. j. wetherell et al. 22 23localized asymmetry in the permanent dentition pirttiniemi p, alvesalo l, silven o, heikkila j, julku j, karjalahti p. 1998. asymmetry in the occlusal morphology of first permanent molars in 45,x/46,xx mosaics. archs oral biol 43:25-32. saunders sr, mayhall j. 1982. developmental patterns of human dental morphological traits. archs oral biol 27:45-49. siegel mi, doyle wj, kelley c. 1977. heat stress, fluctuating asymmetry and prenatal selection in the laboratory rat. am j phys anthropol 46:121-126 seipel cm. 1946. variation of tooth position. sven tandlak tidskr 39: suppl. seow wk, urban s, vafaie n, shusterman s. 1998. morphometric analysis of the primary and permanent dentitions in hemifacial microsomia: a controlled study. j dent res 77:27-38. sharpe pt. 1995. homeobox genes and orofacial development. connect tiss res 32:17-25. stroud jl, buschang ph, goaz pw. 1994. sexual dimorphism in mesiodistal dentin and enamel thickness. dentomaxillofac radiol 23:169-171. taylor rms. 1978. variation in the morphology of teeth. springfield, il: charles c thomas, p 257. thesleff i, keranen s, jernvall j. 2001. enamel knots as decoding your subscription want to know when your subscription to dental anthropology expires? membership in the association and, thus, your subscription to dental anthropology is on an annual basis coinciding with the calendar year. have a look at the mailing label on the evelope that this issue arrived in, and you will see the year for which your dues have been paid. the year is located in parentheses to the right of your name. so, if the mailing label says “(2004)” you are paid to the end of this calendar year. in order to extend your membership, fill-out the relevant portions of the enclosed form (or e-mail the secretary)—remember to include appropriate payment—and mail it to the secretary-treasurer of the association: dr. heather h. edgar maxwell museum of anthropology msc01 1050 1 university of new mexico albuquerque, new mexico 87131-0001 usa telephone: (505) 277-4415 e-mail: hjhedgar@unm.edu signalling centers linking tooth morphogenesis and odontoblast differentiation. adv dent res 15:14-18. townsend gc. 1983. fluctuating dental asymmetry in down’s syndrome. aust dent j 28:39-44. townsend gc and brown t. 1981. the carabelli trait in australian aboriginal dentition. archs oral biol 26: 809-814. townsend g, dempsey p, richards l. 1999. asymmetry in the deciduous dentition: fluctuating and directional components. perspec hum biol 4:45-52. townsend g, richards l, hughes t. 2003. molar intercuspal dimensions: genetic input to phenotypic variation. j dent res 82:350-355. townsend gc, alvesalo l, jensen b, kari m. 1986. patterns of tooth size in human chromosomal aneuploidies. in: russell de, santoro jp, sigogneau-russell d, editors. teeth revisited: proceedings of the viith international symposium on dental morphology, mem mus natn hist nat paris (series c), paris, france 53:25-45. tucker as, sharpe pt. 1999. molecular genetics of tooth morphogenesis and patterning: the right shape in the right place. j dent res 78:826-834. harris and shiloah 2007.2 7 in spite of extensive work on the subject, the forces that cause a tooth to erupt—to move coronally into occlusion—are poorly understood (marks and cahill, 1984; steedle and proffit, 1985; gorski and marks, 1992; wise et al., 2002). indeed, research now suggests that much of the information gleaned from studying rodents (with rootless, continuously erupting incisors) may not apply to humans. moreover, the forces responsible for a tooth’s movement in its pre-emergent phase may be different from those that carry the erupted tooth into occlusion (lee and proffit, 1995; trentini et al., 1995). tooth eruption conventionally refers to the rather rapid movement of a tooth from its formative position in its bony tooth crypt coronally into functional occlusion (sato and parsons, 1990). this is active tooth eruption and, for the permanent teeth, the eruptive phase (ignoring the third molars) starts around 6 years of age and is completed around 12 years of age (hurme, 1949). less well studied is the second, slow and protracted, albeit cumulative phase of tooth eruption termed continuous eruption. this consists of coronal movements of the permanent teeth that occur well after the active phase and that increases in crown height increase lower face height and change facial proportions with age (iseri and solow, 1996). early studies (manson, 1963; bhaskar, 1962) suggested that teeth moved coronally during adulthood such that the cej-to-crestal bone distance increases. the argument a longitudinal study of continued tooth eruption during adulthood edward f. harris* and yoav shiloah college of dentistry, university of tennessee, memphis, tennessee abstract teeth retain their capacity to continue to erupt throughout life. what is less-well appreciated is that occlusal migration—with corresponding alveolar proliferation—continues as a normal process during adulthood. historically, this continuous eruption has been viewed as accommodative for the loss of crown height due to serious occlusal abrasion. nowadays, with only trivial wear, the result of continuous eruption is to increase lower face height during adulthood. this study reports on changes in the mandibular first and second molars in 73 americans whites (63 females) examined at 17 and again at about 31 years of age. a computer-assisted method was used to measure alveolar and dental changes using the inferior alveolar canal as a fiducial benchmark. each molar ’s image was scaled to the mesiodistal molar crown dimension measured from that subject’s dental cast. major findings were: both lower molars erupted during adulthood to statistically significant extents, more so in men. alveolar bone proliferated apace with the coronal tooth migration, so the cej-to-crestal bone distance did not change in these healthy, young, dentate adults. first and second molar roots increased in length, apparently by the progressive deposition of cementum. prior studies have documented continuous eruption in peoples with severe occlusal wear; this study shows that comparable increases occur without any macroscopic loss of tooth substance. these normative changes that—assumedly occur in both jaws—have discernible, cumulative effects on lower face height and facial proportions in adulthood. dental anthropology 2007;20:7-15. *correspondence to: edward f. harris, college of dentistry, university of tennessee, memphis, tennessee �81�� e-mail: eharris@utmem.edu was that teeth erupted more than bony remodeling could keep pace, thereby exposing more root coronal to the bone. these findings were readily criticized because inflammatory periodontitis—which has been prevalent (carranza and newman, 1996)—produces the same increase in cej-to-crestal bone distance over time. subsequent work shows that the “mobile” feature actually is both the tooth and the gingival and crestal bone (murphy, 1959;levers and darling, 1983; whittaker et al., 1990; dannenberg et al., 1991). this difference in perspective was documented definitively by iseri and solow (1996) who studied cephalographs taken by arne björk of people in whom metallic implants had been placed (björk, 1968). in contrast to conventional bony landmarks that remodel with age (e.g., nasion, menton), metallic implants remain immobile, sequestered in the bone proper (enlow, 1977). these metallic implants serve as immobile fiducial landmarks against which skeletodental growth can be quantified without distortion (björk and skieller, 1972, 1977). iseri and solow studied subjects in their later teens and twenties, which is several years after the last teeth had erupted into occlusion (ignoring m3s). findings were (a) that 8 continuous eruption was a normative consequence of ageing, (b) that that continuous eruption occurred in all teeth, and (c) that there was greater coronal eruption of the distal teeth than the anterior teeth, so the occlusal plane flattened with age. while quite informative, this study was restricted to the study of females (one supposes that changes in males would be greater; behrents, 1985; bishara et al., 1994) and, again, most subjects were followed just to their early 20s. one considerable value of this study was its longitudinal design—the same individuals were examined serially—so individual changes with time could be quantified. cross-sectional data are, however, far more available. a key study in this area was by varrela and coworkers (1995). varrela examined archeologically derived material from a european archeological site and grouped the mandibles into age intervals based on age at death. results showed that even accounting for the insensitive cross-sectional nature of the design, continuous eruption—measured as increasing distance from the cementoenamel junction (cej) to the inferior alveolar canal—was evident. as in the study by varrela, most peoples (historically and prehistorically) have exhibited appreciable occlusal wear, which reduces crown height. it commonly has been speculated that continuous eruption is an adaptive, accommodative response to the need to extend a tooth’s functional longevity. continuous eruption provides greater tooth mass before, as was common, occlusal attrition wears the tooth to the gum line. begg, speaking of the prehistoric australian condition, contended that, “tooth eruption does not stop at the neck of the teeth, but proceeds apically to the ultimate shedding of the teeth if we live long enough. continued tooth eruption rendered continual tooth attrition harmless” (begg and kesling, 1971:26). nowadays, with virtually no grit in the diet, occlusal attrition is trivial, even in advanced age, so this accommodative increase in crown height provides no selective advantage. instead, continuous eruption without occlusal attrition simply increases lower face height. purpose of the present study was to test whether continuous eruption is discernible in a sample of contemporary americans who were followed radiographically from their mid-teens to about 30 years of age. the sample consists of people who had received comprehensive orthodontic treatment starting at the conventional age of around 13 years of age, with completion around 16 years of age. the cases were reexamined at a long-term follow-up at an average of 30.7 years of age. this study reports on continuous eruption of the mandibular molars between these two examinations (ca. 17 and 31 years of age). materials and methods data for this study were collected from an on-going project involving the long-term recall of patients who, at adolescence, had received comprehensive orthodontic treatment. the end of treatment averaged 16.7 years (sd = 1.8 years), and the average age at the recall examination was 30.7 years (sd = 6.8 years), so the mean duration was 14.0 years. statistically, there was no difference in any age parameter between males and females. all of the subjects in this study (n = 73) are american whites, and there is a preponderance of females (n = 63) because several women had their recall examination when they brought their own child to the orthodontist for treatment. a computer-assisted photogrammetric method was used to obtain the measurements. the panoramic film was digitized at high resolution on a flat-bed scanner, and the image was imported into sigmascan pro 5.0 (spss inc., chicago, il), where the image was enlarged several-fold (which facilitates landmark location but does not affect actual dimensions), landmarks were located, and the program generated the desired variables. reliance on panoramic radiographs introduces variability because the source-to-film distance and the object-to-film distance are only approximately standardized. when taking a given film, the operator chooses from among a few pre-set trough paths based on the patient’s size and facial form. the “trough” is the two-dimensional pathway that the source (cathode) tracks around the person’s head. ideally, the trough scribed by the machine parallels the shape of the person’s dental arches. landmark studies regarding continuous eruption (thompson and kendrick, 1964; levers and darling 1983) used data collected from panoramic radiographs, though their data were cross-sectional. when studying skeletal specimens, radiation exposure is irrelevant, and bone-holding devices can be rigged to provide stationary periapical (or equivalent) x-rays with known radiographic magnification (whittaker et al., 1990). in the future, the increasingly prevalent use of three-dimensional cone-beam computed tomography will provide measurements that are fully corrected for magnification (e.g., cevidanes et al., 2006, 2007). such long-term longitudinal data are not, however, available now, so we felt warranted in using the panoramic data to test—using longitudinal data—whether changes in tooth length are discernible. in our opinion, long-term longitudinal radiographic data on the living are scarce enough that analysis is warranted—given appropriate caveats—even though the x-rays cannot be exactly standardized. measurements were made using a common technique (whittaker et al., 1985; varrela et al., 1995). the inferior alveolar canal was used as the fiducial landmark. the invariance of this neural structure has been confirmed by the metallic implant studies of björk (1956, 1963). the longitudinal midline of a molar was defined by visual best fit (fig. 1). four landmarks were located along this line: (1) the cementoenamel junction (cej); (2) height of e.f. harris and y. shiloah 9 the crestal bone along the molar’s midline; (3) the apical plane defined by the line through the tooth’s mesial and distal root apices; and (4) superior aspect of the cortical bones of the inferior alveolar canal. in addition, we measured the height of the crestal bone separately at the mesial and distal aspect of the molar down to the iac measured parallel with the molar’s long axis. there is no absolute scale on a panoramic radiograph, so we scaled each image to millimeters by using the specific molar’s mesiodistal crown diameter measured from the dental cast taken at the same appointment. tooth dimensions were obtained in a standardized manner (moorrees, 1957) using sliding calipers. in other words, each individual molar’s mesiodistal crown size was recorded from its panoramic image and from the associated dental cast, and the computer measurements were scaled to millimeters for each tooth. a panoramic radiographic image exhibits variable magnification because the x-ray head is not everywhere equidistant from the dental structures (graber, 1967), but the pathway is least curvilinear in the buccal segment where the molars are situated. as described below, the complex of skeletodental changes found here cannot be explained by differences in magnification. the inferior alveolar canal in the mandible is visible radiographically starting at the lingula and descending downward-and-forward to the premolar region where, in our experience, it seldom can be followed any farther. consequently, we only measured the first and second molars. so far as possible, all four molars in the lower two quadrants were measured, but teeth with poor images were omitted. these young adults were in reasonably good oral health, and each molar was in contact with the tooth mesial to it, so there was no apparent instance of tipping. also, all molars had an antagonist. measurement error is an issue because the changes are fairly subtle. repeatability error was assessed using the conventional dahlberg statistic (dahlberg, 1940; bland and altman, 1996) and the intraclass correlation coefficient (from nested analysis of variance), which is the proportion of the total variation due to differences between measurements of the same individuals (i.e., repeatability error). there was no substantive difference among the types of variables, and, overall, dahlberg’s d was 0.31 mm. that is, the average error due to discrepancies in measurement was one-third of a millimeter, which is appreciably less than any of the statistically significant differences found here. the intraclass correlation was 0.987, meaning that just 1.3% of the observed variation was attributable to discrepancies in measuring the same dimensions repeatedly. statistically, repeated-measures analysis of variance was used to exploit the longitudinal nature of the data as well as the paired m1-m2 comparisons within individuals (winer et al., 1991; sokal and rohlf, 1995). statistics were calculated using jmp 5.0.2 (sas institute inc., cary, nc). results descriptive statistics are presented separately by sex because, as is characteristic (behrents, 1985; bishara et al., 1994), males exhibit more facial growth during their teens and early twenties. also, changes in the first and second molar are described separately because, while the changes are comparable, the second molar is smaller, closer to the inferior alveolar canal (iac), and migrates occlusally somewhat less than m1 (table 1). first molar at t1 (mean = 16.7 years) the root apices were about 5 mm above the iac, and, as shown in table 2, this distance increased to about 6 mm at t2 (mean = 30.7 years). this increase—adjusted to one decade of change across all subjects (table 3)—was about 1 mm/decade in males and half this (which is significantly less) in females, with both changes being highly significant statistically. if, instead, one measures the distance from the iac up to the cej, these increases are appreciably larger. the change in the iac-cej distance was 1.7 mm/decade in males and 1.0 mm/decade in females. again, both of these increases are highly significant (table 3), and the change in men significantly exceeds that in women (table 4). the difference between these two distances (iac to ap and iac to cej) is informative in that it shows that, while m1 is erupting occlusally, there is evidence os: occlusal surface iac: inferior alveolar canal lm: border of mandible cej: cementoenamel junction ac: alveolar margin ap: apical plane of root apices fig. 1. diagram showing the landmarks that were digitized for each mandibular molar. the vertical line through the tooth defines its long axis, and measurements were made along this best-fit line. the landmarks, from top to bottom, depict the crown’s occlusal surface (os), the cej, the alveolar crest (at its intersection with the tooth’s long axis), the root apex (where a line defined by the mesial and distal roots crosses the long axis), the inferior alveolar canal, and the inferior border of the mandibular corpus. continuous tooth eruption 10 e.f. harris and y. shiloah table 1. results of two-way analysis of variance testing for size differences between molars and by sex1 molar2 sex molar-x-sex variable f ratio p value f ratio p value f ratio p value iac to ap, t1 34.43 < 0.0001 0.13 0.7169 1.97 0.2807 iac to ap, t2 54.28 < 0.0001 0.00 0.9837 0.10 0.7538 iac to cej, t1 245.71 < 0.0001 0.00 0.9411 0.02 0.8920 iac to cej, t2 310.50 < 0.0001 1.62 0.2111 2.78 0.1037 root length, t1 70.69 < 0.0001 0.46 0.4997 2.06 0.1592 root length, t2 67.41 < 0.0001 5.30 0.0267 3.35 0.0749 cej to crestal bone, t1 3.55 0.0747 0.53 0.4698 1.16 0.2886 cej to crestal bone, t2 0.55 0.4643 3.02 0.0901 0.11 0.7379 iac to crestal bone, mesial t1 93.47 < 0.0001 0.02 0.9007 0.03 0.8686 iac to crestal bone, mesial t2 153.86 < 0.0001 0.98 0.3275 3.43 0.0716 iac to crestal bone, distal t1 169.55 < 0.0001 0.00 0.9910 0.69 0.4115 iac to crestal bone, distal t2 253.98 < 0.0001 0.18 0.6736 1.15 0.2891 1numerator df is 1 and denominator df is 40 for each test. 2both m1 and m2 could be measured for most subjects, so “molar” was treated as a repeated measure, which provides greater statistical power (but limits the sample sizes to cases where both molars were measurable). the anova is, then, a mixed model. table 2. descriptive statistics, by sex males females variable n mean sd n mean sd mandibular first molar iac to ap, t1 15 5.00 2.18 84 5.49 2.01 iac to ap, t2 15 6.24 2.45 84 6.03 2.02 iac to cej, t1 15 18.89 1.96 84 19.06 2.59 iac to cej, t2 15 21.08 3.00 84 20.15 2.61 root length, t1 15 13.88 1.16 84 13.57 1.66 root length, t2 15 14.84 2.03 84 14.11 1.57 cej to crestal bone, t1 15 1.82 0.35 84 1.98 0.55 cej to crestal bone, t2 15 2.11 0.56 84 1.98 0.57 iac to crestal bone, mesial t1 15 17.94 2.13 84 18.27 2.09 iac to crestal bone, mesial t2 15 19.77 2.83 84 19.07 2.12 iac to crestal bone, distal t1 15 15.81 2.51 84 16.45 2.20 iac to crestal bone, distal t2 15 17.58 2.99 84 17.48 2.17 mandibular second molar iac to ap, t1 10 4.48 2.02 50 4.30 2.56 iac to ap, t2 10 5.16 2.30 50 4.88 2.65 iac to cej, t1 10 16.72 2.27 50 16.40 2.63 iac to cej, t2 10 18.75 3.39 50 17.36 2.88 root length, t1 10 12.24 0.95 50 12.09 1.76 root length, t2 10 13.58 2.07 50 12.48 1.77 cej to crestal bone, t1 10 1.83 0.37 50 1.85 0.50 cej to crestal bone, t2 10 2.32 0.42 50 2.03 0.59 iac to crestal bone, mesial t1 10 16.38 2.78 50 16.18 2.35 iac to crestal bone, mesial t2 10 17.58 3.33 50 16.91 2.52 iac to crestal bone, distal t1 10 13.70 2.84 50 13.50 2.17 iac to crestal bone, distal t2 10 14.57 3.24 50 14.41 2.46 11continuous tooth eruption t a b l e 3 . c ha n ge s st an da rd iz ed t o 1 de ca de , s ex -s pe ci fic o n esa m pl e tte st s of w he th er t he c ha n ge s ar e si gn ifi ca n t st at is ti ca ll y, a n d te st s of w he th er t he a m ou n ts of c ha n ge d if fe r be tw ee n m al es a n d fe m al es te st f or m al es fe m al es se x d im or p h is m v ar ia bl e n m ea n sd tte st p v al u e n m ea n sd tte st p v al u e f ra ti o p v al u e m an d ib u la r fi rs t m ol ar ∆ i a c t o a p 15 0. 98 9 0. 61 2 6. 25 < 0 .0 00 1 84 0. 50 5 0. 69 6 6. 65 < 0 .0 00 1 6. 36 0. 01 33 ∆ i a c t o c e j 15 1. 72 7 1. 01 1 6. 61 < 0 .0 00 1 84 1. 02 1 1. 02 7 9. 11 < 0 .0 00 1 6. 06 0. 01 56 ∆ r oo t l en gt h 15 0. 73 9 0. 91 8 3. 11 0. 00 76 84 0. 51 6 0. 82 0 5. 77 < 0 .0 00 1 0. 91 0. 34 30 ∆ c e jc re st al b on e 15 0. 15 5 0. 51 8 1. 16 0. 26 57 84 -0 .0 43 0. 47 2 0. 83 0. 40 75 2. 17 0. 14 36 ∆ c re st al b on eia c m es ia l 15 1. 42 3 0. 99 6 5. 54 < 0 .0 00 1 84 0. 78 6 1. 06 6 6. 75 < 0 .0 00 1 4. 63 0. 03 38 ∆ c re st al b on eia c d is ta l 15 1. 40 4 0. 66 8 8. 14 < 0 .0 00 1 84 1. 05 2 1. 22 8 7. 85 < 0 .0 00 1 1. 16 0. 28 32 m an d ib u la r se co n d m ol ar ∆ i a c t o a p 10 0. 42 0 0. 45 9 2. 90 0. 01 77 50 0. 47 5 0. 58 5 5. 74 < 0 .0 00 1 0. 08 0. 77 99 ∆ i a c t o c e j 10 1. 34 1 1. 14 6 3. 70 0. 00 49 50 0. 83 7 0. 89 7 6. 60 < 0 .0 00 1 2. 39 0. 12 72 ∆ r oo t l en gt h 10 0. 92 1 1. 05 7 2. 76 0. 02 22 50 0. 36 2 0. 91 0 2. 81 0. 00 70 2. 99 0. 08 93 ∆ c e jc re st al b on e 10 0. 34 1 0. 49 7 2. 17 0. 05 79 50 0. 15 8 0. 53 8 2. 08 0. 04 28 0. 99 0. 32 42 ∆ c re st al b on eia c m es ia l 10 0. 81 1 0. 61 1 4. 20 0. 00 23 50 0. 72 5 1. 16 2 4. 41 < 0 .0 00 1 0. 05 0. 82 18 ∆ c re st al b on eia c d is ta l 10 0. 52 2 0. 75 2 2. 19 0. 05 60 50 0. 85 2 1. 08 2 5. 57 < 0 .0 00 1 0. 84 0. 36 15 of root remodeling (probably cementum deposition) that lengthens the roots and diminishes the apparent movement of the teeth away from the iac. in other words, the roots lengthened from t1 to t2, and the increase was about 0.6 mm/decade in both sexes (fig. 2). the other measurements (tables 1-2) define the molar’s relationship to the crestal bone. the vertical distance from the cej to the crestal bone (measured at the middle of the crown; fig. 1) did not change with time in these healthy subjects. the distance is just under 2 mm at both examinations. on the other hand, measuring height of the cej vis-à-vis the iac makes it evident that the alveolar bone is appositional with age, such that its height increases an average of 1.4 mm/decade in men and a bit less in women (table 3). so, while m1 is slowly erupting to the occlusal, alveolar bone being is deposited to keep pace. table 2 shows that the crestal bone height is roughly 2 mm greater on the mesial than the distal aspect of m1, but this merely reflects the upward curvature of the iac as it courses distally toward the lingula. second molars as shown by the anova tests in table 1, almost all of the dimensions taken at the second molar are substantially different than for m1. this primarily has to do with the upward curve of the iac as it passes beneath this distal molar that provide different distances to the bone and tooth structures compared to m1. while the dimensions differ between teeth, the changes for m1 and m2 are comparable. at t1, apices of the m2 roots were about 4.5 mm superior to the iac, and this distance increased to about 5.0 mm at t2. adjusted to change-perdecade, the iac-ap distances increased about one-half millimeter per decade in both sexes. again, this distance was attenuated by remodeling of the root apices because the increase in the distance from the iac up to the cej is twice as great (table 3), averaging 1.3 mm/decade in men and 0.8 mm/decade in women. at t2, there is suggestive evidence of some crestal bone loss with age, averaging 0.2 to 0.3 mm/decade, which is only marginally significant statistically (p = 0.06 in men; p = 0.04 in women). of note, the net remodeling of bone around m is appositional, because there are increases of around 0.8 mm/decade when bone height is measured relative to the invariant iac rather than the upwardly-migrating tooth. discussion alveolar bone enlow and harris (1964) showed that the corpus is everywhere appositional throughout the active phase of growth, so width and height (and mechanical resilience) of the corpus increase with age. israel (1979) documented that these trends continue well into adulthood. in the present study, dealing with dentate 12 young adults, alveolar bone continued to be deposited along the surface such that corpus height provided by the alveolar crestal bone (above the iac) increased about 1.5 mm/decade in men and just under 1 mm/ decade in women. this bony apposition increases lower face height. the rate is significantly slower in women, though still significant statistically. continuous tooth eruption keeps pace with the proliferation of alveolar bone. indeed, in these healthy young adults, the distance from the cej down to the crestal bone did not change with age even though the molars moved coronally about 1 mm in women and an average of 2 mm in men (table 2). the question of whether the cej has a constant relationship with crestal bone (cb) with advancing age has been contentious, primarily because an increase in this distance can more parsimoniously be attributed to chronic inflammatory periodontal disease than to continued tooth eruption. danenberg et al. (1991) documented significant increases in the cej-cb distance with advancing age in australian aborigines. these authors found no bony evidence of periodontal disease and contended that the increases were evidence of continued tooth eruption during adulthood. other e.f. harris and y. shiloah table 4. results of two-way analysis of variance testing for differences in changes (standardized to 1 decade) from t1 to t2 between molars and by sex1 molar sex molar-x-sex variable f ratio p value f ratio p value f ratio p value iac to ap 1.27 0.2669 0.06 0.8123 0.32 0.5766 iac to cej 1.83 0.1834 3.89 0.0457 1.38 0.2470 root length 0.01 0.9202 5.49 0.0243 0.28 0.6006 cej-crestal bone 0.97 0.3298 5.63 0.0226 1.35 0.2514 iac to crestal bone, mesial 3.66 0.0631 0.67 0.4187 2.66 0.1111 iac to crestal bone, distal 6.38 0.0157 0.03 0.8715 2.33 0.1349 1these are mixed-model anova tests, with repeated measures on molar while sex is a fixed effect; degrees of freedom are 1 and 39 for each test. fig. 2. dimensional changes in lower molars, by sex and molar. the t1 to t2 changes have been standardized to one decade (10 years) on an individual basis. ∆ crestal bone-iac distal ∆ crestal bone-iac mesial ∆ cej-crestal bone ∆ root length ∆ idc to cej ∆ idc to ap ∆ crestal bone-iac distal ∆ crestal bone-iac mesial ∆ cej-crestal bone ∆ root length ∆ idc to cej ∆ idc to ap -0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 change per decade males females 1� researchers (whittaker et al., 1990; varrela et al., 1995) found only small, statistically nonsignificant increases in the cej-cb distance with advancing age. there was no change in this distance in the present study, though these adults may be too young and the interval may be too short to disclose such changes. during the observed age interval, the molars erupted significantly, especially in men, but alveolar bony proliferation was fully as aggressive. continuous eruption continuous eruption refers to a tooth’s life-long potential to further erupt. this capacity is readily observed in people who have lost an antagonist, where the unimpeded tooth supererupts (e.g., compagnon and woda, 1991; yonezu and machida, 1997). similarly, orthodontists have experience “helping” a tooth erupt with the use of traction forces (e.g., stevens and levine, 1998; durham et al. 2004) virtually regardless of the patient’s age. the antithesis of this phenomenon is the ankylosed tooth (and osseointegrated implant) that becomes progressively submerged as adjacent teeth and surrounding alveolar bone continue to migrate occlusally (ödman et al., 1991; roberts, 1994). of more general relevance, is whether continuously eruption is a dentition-wide phenomenon that characteristically occurs in all adults? prior studies (newman and levers, 1979; whittaker et al., 1982, 1985, 1990; varrela et al., 1995) have shown that continous eruption does occur during adulthood, but (a) these studies have been crosssectional, based on skeletal remains of subjects who died at different ages, (b) most studies have combined males and females, and (c) studies have used peoples who experienced moderate-to-severe occlusal wear because they lived on coarse, abrasive diets. it might be argued (levers and darling, 1983) that substantial occlusal wear increases freeway space, thereby “making room” for additional, compensatory tooth eruption. what happens in the absence of attrition? the modern american diet is so highly refined and grit-free that young adults present without any wear facets and most people never experience dentin exposure due to dietary abrasion. consequently, there is only inconsequential loss of vertical dental height. the theme of some studies has been that continous eruption occurs because of substantial attrition. for example, begg (1954) contended that the severe occlusal wear that occurred in prehistoric australian aboriginals “made room” for the teeth to erupt farther. murphy (1959), levers and darling (1983), and several others likewise have assumed that continuous eruption is the respondent and occurred when the opportunity was created by occlusal abrasion. as seen in the present study, eruption is occurring continuously and seemingly at equivalent rates even in the absence of any macroscopic abrasion. whittaker et al. (1990) reported comparable findings from a 19th century british series where abrasion was slight. it seems that eruption is an ongoing physiological process that is indifferent to whether the crowns are worn down. it may well be that tooth eruption proceeds during adulthood simply because the forces causing eruption are never disabled. the present study shows that lower face height is enhanced because the tooth itself migrates occlusally (presumably in both arcades; iseri and solow, 1996) but also because bone is proliferating apace with the teeth. the present study also documents the significantly greater rate of growth in men than women, notably in the vertical dimension. this is consistent with cephalometric studies of changes during adulthood (e.g., forsberg, 1979; behrents, 1986; bishara et al., 1994) where growth is notably greater in men. the same has been reported from earlier, cross-sectional craniometric studies of dentate adults (lasker, 1953; thompson and kendrick, 1964). this also was documented by west and mcnamara (1999) who suggested that the increase in lower face height “probably is compensatory, resulting from either continued dental eruption, continued alveolar growth, or both, to balance the occlusions with the skeletal growth that is occurring.” opinions may differ as to what skeletodental changes are “balancing” and compensatory and which are passive respondents, but the net effect is slow but cumulative increase in adult facial dimensions, and the present study confirms that both tooth eruption and alveolar growth are contributory. root length at first impression, it probably is surprising to find that root length increased with age in this study, both for m1 and m2 and in both sexes. indeed, the more common issue in the orthodontic literature deals with how treatment causes apical root resorption (samehsima and sinclair 2001a,b; harris 2000), though there seems to be no posttreatment progression of the problem (remington et al., 1989). review of the literature suggests that there are very few longitudinal studies of root dimensions in adults. cross-sectional studies, such as by woods and coworkers (1990), typically encounter too much inter-individual variability to find any trend with age. the study by bishara et al. (1999) is the most informative here. bishara and coworkers had periapical films of the same 26 individuals at an average age of about 25 years and again at 45 years of age. six of their comparisons of 32 root lengths (of 28 teeth) exhibited statistically significant increases in root length over time. however, when the bonferroni correction for multiple comparisons was applied (which may be too conservative—see holm, 1979; rice, 1989), none of the changes remained significant. this led the authors to conclude “that there were no significant changes in root lengths between 25 and 45 years of age in either males or females.” this conclusion is perhaps overly cautious since other continuous tooth eruption 14 studies—albeit cross-sectional—have found that root lengths increase discernibly with age. researchers have consistently attributed these increases to the accumulation of cementum, which is known to accumulate at a fairly regular pace (wittwer-backofen et al. 2004). levers and darling (1983) reported “continuous lengthening” of the roots with age, “presumably by cementum deposition.” whittaker et al. (1990) found that root apices migrated away from the iac significantly less than the cej, which they attributed to cementum apposition that lengthened the roots. similarly, varrela et al. 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michels km. 1991. statistical principles in experimental design, 3rd ed. new york: mcgraw-hill book company. wise ge, frazier-bowers s, d’souza rn. 2002. cellular, molecular, and genetic determinants of tooth eruption. crit rev oral biol med 13:323-334. wittwer-backofen u, gampe j, vaupel jw. 2004. tooth cementum annulation for age estimation: results from a large known-age validation study. am j phys anthropol 123:119-129. woods ma, robinson qc, harris ef. 1990. ageprogressive changes in pulp widths and root lengths during adulthood: a study of american blacks and whites. gerodontology 9:41-50. yonezu t, machida y. 1997. occlusal migration of the maxillary first primary molars subsequent to the loss of antagonists. bull tokyo dent coll 38:201-206. continuous tooth eruption swindler 2002.5 26 27 polydontia (extra teeth) are found in both extinct (jungers and gingerich, 1980) and extant primate taxa (colyer 1936; krapp and lampel, 1973; lavelle and moore, 1973; miles and grigson, 1990; schultz, 1935). but as jungers and gingerich (1980:1) mentioned in their investigation, “the developmental basis of extra teeth in a particular tooth category remains obscure.” several explanations have been proffered through the years regarding the development of fourth molars, e.g., distal growth of the dental lamina, duplication of the m3 tooth germ and atavism (see in particular jungers and gingerich, 1980; miles and grigson, 1990). the fourth molar is a rarity in the genus macaca. in an ongoing longitudinal study of dental development in macaca nemestrina , m 4 and m4 were observed radiographically in a male specimen. development of the m4 is discussed and the appearance and frequency of m4’s in the anthropoidea is reviewed. materials and methods the parental generation was collected from freeranging populations in sumatra and transported to the national primate research center at the university of washington. these animals were the breeding colony of the animals in the longitudinal growth and development study (sirianni and swindler, 1985). after weaning, between 3 and 8 months, the animals were raised and housed separately with their age mates. radiographs of the head in norma lateralis were taken on a regular schedule from about three months to seven years. there were a total of 140 animals in the study, 70 females and 70 males. tables 1, 2 and 3 present the number of specimens with m4’s except for the figures presented of selenka (1898), hrdli�ka (1907) and hooijer (1948) in table 2 that record the total number of m4’s results and discussion the m4 was observed in the radiograph of one male and was present in both the maxilla and mandible. thus of a total sample of 140 macaca nemestrina 0.7% showed this condition (table 1). a slightly lower percentage has been reported for the presence of m4 for the genus macaca by miles and grigson, 0.2% of 901 animals (1990), lavelle and moore (1973) recorded 0.3% for 350 macaca abstract fourth molars are not common in the anthropoidea. orangutans possess the highest frequencies (7-13%) while many genera in the suborder lack the fourth molars. a review of the incidence of m4’s in daris r. swindler department of anthropology, university of washington, seattle, wa 98195 u.s.a fourth molars in the anthropoidea daris r. swindler, department of anthropology, university of washington, seattle, wa 98195 u.s.a. e-mail: dswindle@u.washington.edu table 1. incidence of m4’s in the cercopithecidae number of genus specimens m4 percent colobus1 1,485 22 4.00 colobus2 140 0 0.00 colobus8 155 5 3.23 presbytis1* 289 1 0.30 presbytis2 100 0 0.00 presbytis8 321 1 0.31 pygathrix1 16 0 0.00 rhinopithecus1 17 0 0.00 rhinopithecus3 11 1 9.10 simias1 10 0 0.00 nasalis1 83 0 0.00 cercopithecus1 1,823 10 0.50 cercopithecus2 350 4 1.10 cercopithecus8 2,460 16 0.65 erythropithecus1 95 3 3.20 erythropithecus8 95 2 2.11 cercocebus1 311 0 0.00 papio1 410 2 0.50 papio2 38 1 2.60 papio8 541 6 1.11 mandrillus1 56 0 0.00 theropithecus1 7 0 0.00 macaca1 901 2 0.20 macaca4 140 1 0.70 macaca2 350 1 0.30 macaca8 2,379 9 0.38 1miles and grigson (1990) (m4 and m 4 ) 2lavelle and moore (1973) (m4 and m 4 ) 3hooijer(1952) (m4) 4this paper (m4 and m 4 ) 8krapp and lampel (1973) (m4 and m 4 ) *p. entellus and vetulus groups the anthropoidea is presented and a description of the ontogeny of m4 in macaca nemestrina is described and offered as an explanation of the development of m4’s in this taxon. 26 27 fig. 2. macaca nemestrina 7.0 years old. m 4 crown complete and initial emergence has begun. there appears to be initial mineralization of m4 within a crypt. fig. 1. macaca nemestrina 6.2 years old. m 4 crown visible within its crypt distal to m 3 . an interdental bony septum separates m 4 from m 3 . fourth molars 1, 2 and 3). gibbons appear to lack development of m4, a fact that has been known since the work of bateson (1894) as reported in miles and grigson (1990). also, several different genera of both new and old world monkeys lack the 0ccurrence of m4. the taxonomic presence of m4’s in the living anthropoidea seems to lack any discernible correlation with body mass or facial prognathism since the m4 condition appears in primates ranging in size from gorillas to squirrel monkeys and in primates with both long and short snouts. the aetiology of polydontia is uncertain. earlier literature suggested that such occurrences were the result of atavism, although today the term has lost favor in most scientific circles. the heritability of the condition is not completely understood (finn, 1967); however, there is evidence indicating that polydontia appears more often in isolated populations, and especially among some domesticates, which has suggested thethe involvement of genetic drift as a possible cause to miles and grigson (1990). “connate teeth” is an anomaly; that is, double teeth, incomplete dichotomy, or syndonty that should be reserved for teeth that are “developed or born together” (miles and grigson, 1990; winkler and swindler, 1993; drusini and swindler, 1994). in the present case, both the upper and lower m4 would seem to represent the continued distal growth of the dental lamina in that m4 appears distally to the formation of m3. the development of m 4 will be discussed since it is more easily observed and it is assumed that m4 passed through similar developmental stages. the dental follicle and m 4 appear between 5.5 and 6.2 years. at 6.2 years the crown is present, the cusps are connected but the crown is not complete and it is inclined obliquely at about 450 to the occlusal plane (fig. 1). there is no root development and the cleft has not yet formed, and as seen in this radiograph, an interdental septum separates m 3 and m 4 (fig.1). in fig. 2, (7.0 years), the crown appears nearly formed with beginning root formation while the crown is still inclined relative to the occlusal plane. the mesiodistal length of the crown is 8.5 mm which is about 3 mm shorter that the average size of m 3 in male m. nemestrina (10.9 mm) and about equal in length to m 2 (8.6 mm) (swindler, 2002). thus, this m 4 is within the normal mesiodistal size range for molars of m. nemestrina. unfortunately, this animal was not studied after 7 years of age so there is no information regarding the age of the animal when m 4 emerged. conclusion the presence of m4’s is rare among living primates, particularly in gibbons, new world monkeys and colobine genera. the orangutans possess the highest frequency of m4’s (7 to 13%) of all living anthropoidea. the aetiology of m4’s remains uncertain and may represent different developmental processes in different as having total polygenesis but did not designate which teeth were involved. krapp and lampel (1973), in their comprehensive study of dental anomalies of living anthropoidea, found 0.38% of 2,379 macaque specimens with fourth molars. the presence of extra teeth is low in all living cercopithecids irrespective of the tooth group, and it is interesting to note that most investigations have found a higher incidence of m4’s in the subfamily cercopithecinae than in the colobinae, (table 1). a notable exception to this finding is the 9.1% presence in rhinopithecus; however, that figure represents one specimen out of a total of only eleven animals (table 1). of all the genera depicted in tables 1, 2 and 3, pongo has the highest frequency of m4 while colobines and new world monkeys generally have the lowest frequencies. among living primates, pongo is generally reported to have the highest percentage of m4’s (tables 28 29 species. on the basis of the present specimen, it seems clear that m 4 develops in a normal manner i.e., follicle, initial calcification, crown formation and root formation from a distal extension of the dental lamina, and that tooth formation takes place in a follicle distal to an interdental septum between it and m 3 . references cited bateson w. 1894. materials for the study of variation. london: macmillian. colyer jf. 1936. variations and diseases of the teeth of animals. london: john bale, sons & danielsson. drusini ag, swindler dr. 1994, connate incisors in a pre-columbian mandible from nasca, peru. dental anthropology newsletter 9:11. hooijer da. 1948. prehistoric teeth of man and the orang-utan from central sumatra, with notes on the fossil orang-utan from java and southern china. zoologische mededeelingen museum, leiden, 29: 175-301. hooijer da. 1952. notes on the dentition of the golden monkey rhinopithecus. j. mammology 33:258-260. hrdlička a. 1907. anatomical observations on a table 2. incidence of m’s in the pongidae and hylobatidae number of genus specimens m4 percent gorilla1 546 22 4.00 gorrila2 190 12 6.30 gorilla8 1,409 56 4.00 pan1 467 13 2.40 pan2 100 2 2.00 pan8 1,040 28 2.72 pongo1 229 16 7.00 pongo2 100 6 6.00 pongo5 88 6 6.80 pongo6 388 46 11.90 pongo7 44 6 13.60 pongo8 1,808 200 11.12 hylobates1 * 391 3 0.80 hylobates2 150 0 0.00 hylobates8 1,276 9 0.71 1miles and grigson (1990) (m4 and m 4 ) 2lavelle, and moore (1973) (m4 and m 4 ) 5hooijer (1948) (m 4 ) 6selenka (1898) (m 4 ) 7hrdlička (1907) (m 4 ) 8krapp and lampel (1973) (m4 and m 4 ) *hylobates and symphalangus table 3. incidence of m’s in the cebidae number of genus specimens m4 percent lagothrix1 94 0 0.00 brachyteles1 25 0 0.00 ateles1 232 7 3.00 ateles8 612 6 0.98 saimiri1 110 1 0.90 saimiri8 100 1 0.10 cebus1 651 4 0.60 alouatta1 787 3 0.40 alouatta8 956 3 0.31 cacajao1 23 0 0.00 pithecia1 155 0 0.00 callicebus1 122 0 0.00 aotus1 10 0 0.00 1miles and grigson (1990) (m4 and m 4 ) 8krapp and lampel (1973) (m4 and m 4 ) collection of orang skulls from western borneo. proc us natl mus 31:539-568 jungers lj, gingerich pd. 1980. supernumerary molars in anthropoidea, adapidae, and archaeolemur: implications for primate homologies. am j phys anthropol 52:1-5. krapp f, lampel g. 1973. zahnanomalien bei altweltaffen (catarrhina). rev suisse zool 80:83150. lavelle clb, moore wl. 1973. the incidence of agenesis and polygenesis in the primate dentition. am j phys anthropol 38:671-680. miles aew, grigson c. 1990. colyer’s variations and diseases of the teeth of animals. cambridge: cambridge university press. schultz ah. 1936. the eruption and decay of the permanent teeth in primates. am j phys anthropol 19:489-581. selenka e. 1898. rassen, schadel und bezahnung des orangutan. menschenaffen (anthropomorphae). studien uber entwicklung und schadelbau. wiesbaden: cw kreidels verlag. sirianni je, swindler dr. 1985. growth and development of the pigtailed macaque. boca raton: crc press, inc. swindler, dr. 2002. primate dentition: an introduction to the teeth of non-human primates. cambridge: cambridge university press. winkler la, swindler dr. 1993. report: presence of a connate tooth in a neonate chimpanzee. dental anthropology newsletter 8:9. fourth molars bracha et al. 2004.4 78 79 there has been a rapidly growing interest in developing animal models resembling human situations of extreme life threat (e.g. military combat). for example, heart-rate variability (hrv) is now extensively studied in animals since hrv has been one of the more consistent physiological markers for research on combat-related posttraumatic stress disorder (cr-ptsd) and post-deployment syndromes of unclear etiology (gorman and sloan, 2000; malaspina et al., 1997; shalev, 2002). porges has recently called attention to the vagal motor neurons originating in the nucleus ambiguus and their link to hrv (porges, 1995). to our knowledge, dental anthropological techniques h. stefan bracha1*, d. caroline blanchard2, jeffrey l. lloyd-jones1, andrew williams1,3, robert j. blanchard3 1national center for posttraumatic stress disorder, department of veterans affairs, pacific islands health care system, spark m. matsunaga medical center, 1132 bishop st. suite 307, honolulu, hawaii, 96813-2830 usa 2university of hawaii at manoa, department of anatomy, honolulu, hawaii, 96822, usa 3university of hawaii at manoa, department of psychology, honolulu, hawaii, 96822, usa this material is based upon work supported in part by the office of research and development, medical research service, department of veterans affairs, va pacific islands health care system, spark m. matsunaga medical center. support was also provided by a national alliance for research on schizophrenia and depression (narsad) independent investigator award, and the va national center for posttraumatic stress disorder. *correspondence to: h. stefan bracha, national center for posttraumatic stress disorder, department of veterans affairs, pacific islands health care system, spark m. matsunaga medical center, 1132 bishop st. suite 307, honolulu, hawaii, 96813-2830 usa e-mail: h.bracha@med.va.gov abstract: developmental defects of enamelstress histomarker rings (accentuated striae) may be a potential measure of diminished vagal tone in research on extreme stress such as exposure to combat. to develop an animal model of this measure, we examined the enamel of rat incisors which erupt continuously. we examined incisors from 15 stressed-colony rats and 7 control-group rats for these histomarkers using the visible burrow system (vbs). vbs was developed to study combat stress in rats. no stress rings were found in any of the rat incisors examined. in contrast to humans, rats have likely evolved to prioritize incisor strength during combat stress. studies of amelogenesis during combat stress in other rodents with continuouly growing incisors are warranted. laboratory animals such as rabbits or marmosets may be especially suitable, since they less frequently use their incisors for selfdefense. dental anthropology 2004;17(3):79-82. have not been previously used in research on combatstress biology (bracha et al., 2003). in the anthropological literature, there has been little attention given to the fact that in addition to their role in hrv, the vagal motor neurons originating in the nucleus ambiguus also control the moment to moment fluctuations in the parasympathetic regulation of blood flow to the enamel secreting ameloblasts (as well as to the adjacent salivary glands). in humans, several tissues (e.g., intestinal mucousae, other mucousae, skin, bone, teeth, hair, and nails) are of lower survival priority during life-threatening experiences such as war-zone exposure. these tissues grow predominantly during spans of high vagal tone such as rest and sleep (appenzeller et al., 2002; appenzeller, 1990; bracha et al., 2003; bracha et al., 2004; bracha, 2004). studying these anatomical structures of lowest survival priority may experimental combat-stress model in rats: histological examination of effects on amelogenesis— a possible measure of diminished vagal tone episodes 80 81 be a novel research approach to examine the negative effects of combat-related stress. while little research has been done on the topic, amelogenesis of the still erupting teeth is one parasympathetic trophic “luxury” function likely to be among the lowest priorities during extreme stress and thus provides a sensitive stress indicator in humans (yui et al., 2002; bracha et al., 2002). unlike nails, and most of the human bones, skin and mucousae, the parasympathetic innervation of the ameloblast layer and the nearby salivary gland and larynx originates not in the dorsal motor nucleus of the vagus, but in the more rostral and more limbic-connected nucleus ambiguus of the vagus. this neural circuit is known to be involved in the human fear response (porges, 2001; porges, 1995; bracha et al., 2003). the amelogenesis defects seen in human tooth enamel have been reproduced using laboratoryinduced stress in large herbivores such as sheep, pigs, and deer (guatelli-steinberg, 2001; guatellisteinberg and lukacs, 1999; suckling et al., 1986; dean et al., 2001; dirks et al., 2002). for our line of clinical research, which focuses on the effect of combat stress on mineralized tissues such as bones and teeth, rodent incisors are an especially attractive tissue in which to examine histological biomarkers of extreme stress. the constant gnawing motion of the rat’s jaw rapidly wears the incisors. therefore, new enamel is formed in the ameloblast layer to replace the worn incisor enamel throughout the lifetime of the rat. while enamel research in dental anthropology has focused on nutritional or chronic stress, this is to our knowledge, the first controlled study attempting to use dental anthropological techniques to understand the effects of combat stress. to study the effects of combat-like stress on mineralized dental tissue, we used the visible burrow system (vbs) developed by blanchard et al. (blanchard et al., 1995). the vbs is an important novel system to study combat stress among rats (monder et al., 1994). using the vbs, acute episodes of combat stress can be experimentally induced at known intervals. previous studies have shown that behavior highly reminiscent of human combat ensues among male rats in the vbs. for a review of the vbs, see blanchard et al. (blanchard et al., 1995) and monder et al. (monder et al., 1994). methods using the vbs, we controlled the timing of experimental combat stress in male rats and subsequently studied its effects on mineralized dental tissue formation. we examined 22 male rats that were subjected alternately to stressed and unstressed periods over several months. during the three-week baseline (no-stress) period the male rats were kept in individual cages. during the second three-week (low stress) period, rats from the control group (n=7) were each placed in cages with a single female rat. during the same three-week (combat-stress) period, the test rats (n = 15) were placed in colonies of three male rats to one female rat. during this combat-stress period, a behavior highly reminiscent of human combat ensued among the male rats (blanchard et al., 1995). after this period, the rats were returned to their individual cages for another three-week (no-stress) period. this cycle was repeated three times for all of the rats in the study. after the three combat-stress cycles, the two upper and two lower incisors from each rat were removed. the incisors from a total of 15 stressed-colony rats and 7 control-group rats were examined for “developmental defects of enamel-stress histomarker rings” (ddesh rings; also known in dental anthropology as “accentuated striae”). the rat teeth were examined at 10x, 100x, and 400x by a trained dental anthropologist (jllj) who was blind to group assignment. results at least 3 teeth were available from each of the 22 rats. because of the curvature of the rat incisors in the sagittal plane, one of the two lower incisors from each of four rats were not suitable for sectioning leaving us with 84 incisors out of a possible 88. unlike human teeth, the rat teeth showed markedly more decussation of the enamel rods giving them a twisted rope-like appearance. no dde-sh rings (accentuated striae) were found in any of the 84 incisors examined regardless of group assignment. discussion these negative results replicate and extend earlier research demonstrating the unusually high stressresilience of rat amelogenesis. fejerskov, using earlier stress-inducing methods reported similar negative results (fejerskov, 1979). we propose that the explanation for this inter-species difference in the response to acute combat stress involves inter-species evolutionary differences in stress-response adaptation. it is likely that the rat genome has evolved to place high priority on incisor strength during life threatening experiences. unlike humans and herbivores (such as sheep and deer), incisor strength is unlikely to be a luxury function for rats involved in combat. from an evolutionary point of view, short-term survival of the rat is more dependent on the stress-resilience of their incisors. therefore, rat incisors may have evolved to achieve a greater degree of stress-resilience compared with sheep, deer, or human incisors. our finding that rat incisors show dramatically more enamel rod decussation is consistent with the above speculation. enamel rod decussation is a histological feature known to increase the strength of h.s. bracha et al. 80 81 enamel (fejerskov, 1979). preliminary data using enamel stress rings to chronicle episodes of diminished vagal tone in human teeth are promising (bracha et al. unpublished). therefore, it may be premature to abandon all laboratory animals as experimental models of acute episodes of extreme stress. for example, small herbivores, which in the wild only infrequently use their incisors for combat, may be a better choice than rats. marmosets and rabbits, like rats, have constantly growing incisors and are as easy to study. however, marmosets and rabbits may resemble humans in stress prioritization with regard to the ameloblast tissue layer. therefore their incisor enamel may be a promising model for research on combat stress. additionally, the newly developed animal research designs which induce extremely stressful but nonlethal exposure to larger predators (cohen et al., 2003) may be especially useful for this line of research on the effects of acute combat stress on calcified tissue. the latest national institute of mental health (nimh) recommendations for future research directions on fear-circuitry disorders emphasize the “… need [for] research designed to develop better measures of the environment...” and the need to have “stress conceptualized broadly” (davidson et al., 2002). similar conclusions were drawn by charney (charney, 2004). developing an experimental rodent model of dental biomarkers of acute stress is also consistent with the conclusions of the nimh workshop on developing newer animal models of anxiety disorders (shekhar et al., 2001). the line of research described here is well suited to address the above recommendations. a new technique for estimating vagal tone chronology may be a useful complement to the important research on hrv in laboratory animals and humans (porges, 1995; cohen et al., 2003). in summary, laboratory animals that infrequently use their constantly growing incisors for combat may be a better choice than rats for this line of combat stress research. research designs that provide extreme but non-lethal exposure to larger predators are especially recommended for this line of research. acknowledgements the authors thank colonel donald a. person md, jennifer m. matsukawa ma, and tyler c. ralston ma for comments on sections of this manuscript. an earlier version of this paper was presented at the american college of neuropsychopharmacology (acnp) 2001 annual meeting, kamuela, hawaii and at the north atlantic treaty organization (nato) – advanced research workshop “formal descriptions of developing systems,” university of hawaii, october 2 to 6, 2002. references cited appenzeller, o. (1990). the autonomic nervous system: an introduction to basic and clinical concepts. amsterdam: elsevier. appenzeller o, cornelissen g, halberg f, wallace j, costa ma. 2002. biological rhythms and behavior— then and now. med sci monit 8:27-30. blanchard dc, spencer rl, weiss sm, blanchard rj, mcewen b, sakai rr. 1995. visible burrow system as a model of chronic social stress: behavioral and neuroendocrine correlates. psychoneuroendocrinology 20:117-134. bracha hs, williams ae, haynes sn, kubany es, ralston tc, yamashita, jm. 2004. the strs (shortness of breath, tremulousness, racing heart, and sweating): a brief checklist for acute distress with panic-like autonomic indicators; development and factor structure. ann gen hosp psychiatry 3:8. bracha hs. 2004. can premorbid episodes of diminished vagal tone be detected via histological markers in patients with ptsd? int j psychophysiol 51:127-133. bracha hs, lopez, hh, flaxman na, lloyd-jones jl, bracha as, ralston tc. 2002. can enamel serve as a useful clinical marker of childhood stress? hawaii dent j 12:9-10. bracha hs, yamashita jm, ralston tc, lloyd-jones, j, nelson g, bernstein dm, flaxman na. 2003. clinical research histomarkers for objectively estimating premorbid vagal tone chronology in gulf war veterans’ illnesses and in acute stress reaction. in: nation j, trofimova i, rand jd, sulis w, ediors. formal descriptions of developing systems (nato science series). dordrecht: kluwer academic publishers, p 279-288. charney ds. 2004. psychobiological mechanisms of resilience and vulnerability: implications for successful adaptation to extreme stress. am j psych 161:195-216. cohen h, zohar j, matar m. 2003. the relevance of differential response to trauma in an animal model of posttraumatic stress disorder. biol psych 53:463473. dean mc, leakey mg, reid dj, friedeman s, schwartz gt, stringer c, walker a. 2001. growth processes in teeth distinguish modern humans from homo erectus and earlier hominins. nature 414:628-631. dirks w, reid dj, jolly cj, phillips c, brett fl. 2002. out of the mouths of baboons: stress, life history, and dental development in the awash national park hybrid zone, ethiopia. am j phys anthropol 118, 239-252. fejerskov o. 1979. human dentition and experimental animals. j dent res 58:725-734. experimental combat-stress model 82 83 gorman jm, sloan rp. 2000. heart rate variability in depressive and anxiety disorders. am heart j 140: 77-83. guatelli-steinberg d. 2001. what can developmental defects of enamel reveal about physiological stress in nonhuman primates? evol anthropol 10:138-151. guatelli-steinberg d, lukacs jr. 1999. interpreting sex differences in enamel hypoplasia in human and nonhuman primates: developmental, environmental, and cultural considerations. yrbk phys anthropol 42:73-126. malaspina d, bruder g, dalack gw, storer s, van k, amador,x, glassman a, gorman j. 1997. diminished cardiac vagal tone in schizophrenia: associations to brain laterality and age of onset. biol psych 41:612617. monder c, sakai rr, miroff y, blanchard dc, blanchard rj. 1994. reciprocal changes in plasma corticosterone and testosterone in stressed male rats maintained in a visible burrow system: evidence for a mediating role of testicular 11_-hydroxysteroid dehydrogenase. endocrinol 134:1193-1198. porges sw. 1995. cardiac vagal tone: a physiological index of stress. neurosci biobehav rev 19:225-233. porges sw. 2001. the polyvagal theory: phylogenetic substrates of a social nervous system. int j psychophysiol 42:123-146. shalev ay. 2002. acute stress reactions in adults. biol psych 51:532-543. shekhar a, mccann ud, meaney mj, blanchard dc, davis m, frey ka, liberzon i, overall kl, shear, mk, tecott lh, winsky l. 2001. summary of a national institute of mental health workshop: developing animal models of anxiety disorders. psychopharmacology (berlin) 157:327-339. suckling gw, elliott dc, thurley dc. 1986. the macroscopic appearance and associated histological changes in the enamel organ of hypoplastic lesions of sheep incisor teeth resulting from induced parasitism. arch oral biol 31:427-439. yui k, bracha hs, nishijima k, kamata y, kato s. 2002. pathological stress lines in human molars as a biological marker of early stress. brain sci ment disorders 13:443-450. h.s. bracha et al. editor’s note: this article is from the honolulu va dentaltissue repository. the repository involves a new longitudinal study of predictors of psychosocialstress resilience in young adults. the study includes a comparison of ameloblast distress episodes (i.e., accentuated striae) that developed in the teeth between about 8 and 11 years (the period of third molar amelogenesis) along with the subject’s selfreported and pediatrician-reported allostatic load between ages 7-11 and 11-18 years. extensive psychosocial-allostasis measures are available from this unique american multi-ethnic group of 307 living, healthy, young middle-class men and women in honolulu, hawaii (in whom purely physiological, and nutritional allostasis is extremely low.) open access to some of the already published psychosocial-allostatic data is at: http://www.annals-general-psychiatry.com/ content/pdf/1475-2832-3-8.pdf two or more third molars are available on each of these 307 research participants. 100 of the participants already have enamel and dentin histological sections analyzed in collaboration with donald j. reid, phd. researchers interested in collaborations using this large database, or conducting further histological examination of the sections of the 307 teeth can contact the principal investigator at this address: h. s. bracha, m.d. research psychiatrist national center for ptsd department of veterans affairs pacific islands health care system, spark m. matsunaga medical center 1132 bishop street, # 307 honolulu, usa 96813-2830 h.bracha@med.va.gov phone: 808.566.1652 fax: 808.566.1885 http://www.annals-general-psychiatry.com/content/pdf/1475-2832-3-8.pdf http://www.annals-general-psychiatry.com/content/pdf/1475-2832-3-8.pdf nelson 2000.4 pg24.jpg pg25.jpg haeussler 1999a.2 pg05.jpg pg06.jpg pg07.jpg pg08.jpg pg09.jpg pg10.jpg pg11.jpg pg12.jpg pg13.jpg pg14.jpg haeussler 1999b.5 pg16.jpg pg17.jpg delgado-burbano 2008.1 33 *correspondence to: miguel eduardo delgado-burbano, división de antropología. facultad de ciencias naturales y museo. universidad nacional de la plata. paseo del bosque s/n. la plata 1900, buenos aires, argentina. e-mail: medelgado@fcnym.unlp.edu.ar discontinuous variation in the permanent dentition of modern homo sapiens has been systematically studied from a worldwide level (scott and turner, 1997). in contrast, relatively little is known about modern human evolution as depicted in the primary dentition. several characters in the deciduous dentition are evolutionarily conservative and have deep phylogenetic and ontogenetic stability in comparison to some traits in the permanent dentition (edgar and lease, 2007). moreover, the early development of deciduous dentition in utero allows less external perturbations (smith, 1978; smith et al., 1987). however, some aspects of the deciduous dentition’s evolutionary dynamics are not well known, and its use for the study of human evolution is scarce (kitagawa, 2000; sciulli, 1998; smith, 1978; grine, 1984; lukacs and walimbe, 1984; lease, 2003; lease and sciulli, 2005; delgado-burbano, 2007). although phenotypic characters shown indirectly genetic relationships and environmental factors may affect the underlying genotype, dental nonmetric traits are reliable skeletal characters since they are strongly controlled by polygenic systems and present high heritability values (e.g., townsend and martín, 1992; nichol, 1989). several investigations provide information about deciduous nonmetric variation from a local scale in several human groups from asia and the pacific (hanihara, 1956ab, 1961, 1963, 1965, 1966; hanihara and minamidate, 1965; sasaki and kanasawa, 1998; kitagawa, 2000), africa (grine, 1984, 1986, 1990; lease, 2003), india (lukacs and walimbe, 1984; lukacs and hemphill, 1991), europe (lease, 2003; jørgensen, 1956), near east (smith, 1978; smith et al., 1987; moskona et al., 1998), australia (townsend and brown, 1981; townsend et al., 1986, 1990) and north america (sciulli, 1977, 1990, 1998, tocheri, 2002; ullinger, 2003; lease, 2003; lease and sciulli, 2005; edgar and lease, 2007). surprisingly, past and present south american populations have received little attention (delgado-burbano, 2007). although the current use of molecular variants (i.e., mtdna, y chromosome and autosomal markers) in the study of population history and biological variability of modern human populations is very popular, studies based on phenotypic variation continue to play an important role. the study of phenotypic diversity can help us understand the evolution and biocultural variation of the contemporary communities that today inhabit south america and to obtain a more complete landscape of the dynamics that configure their gene pool. the aims of the present research are to (1) characterize some colombian communities through their deciduous dental variation, (2) assess this diversity in a regional context, and (3) suggest interpretations of their population history, affinities and microevolution. deciduous dental morphological diversity in contemporary colombian ethnic groups miguel eduardo delgado-burbano* división antropología, facultad de ciencias naturales y museo, universidad nacional de la plata, la plata 1900, buenos aires, argentina abstract: biocultural diversity of contemporary south american populations has not been studied extensively, therefore delineating some of the patterns of phenotypic variation may be useful for understanding their ongoing evolution. thirty-seven deciduous dental nonmetric traits were scored on 200 dental casts that were obtained from four contemporary colombian ethnic groups with different ancestry. inter-group affinities were assessed by means of a principal component analysis based on trait frequencies. african-american colombian groups share several dental morphological affinities with other new world african derived populations as well as with sub-saharan african dental samples. colombian amerindians have a relative affinity with prehistoric native north american samples, but a clear association with living north american indians and recent northeast asian sinodont populations was not evident. the biologically admixed group or “mestizo” has a more complicated pattern of phenotypic relationships, with an african and an amerindian but not an evident european component. from an evolutionary point of view, gene flow probably is the most important factor that changed the original gene pool through time. these groups have a complex landscape of biocultural variation reflected by their different microevolutionary histories. dental anthropology 2008;21(2):33-45. 34 materials and methods study subjects dental casts (n = 200) were collected and analyzed from four communities with different ethnic ancestry located in the southwest of colombia (fig. 1). sex distribution and sample size for the groups are presented in table 1. sixty-eight dental models are from afro-colombian individuals of the guapi community in the colombian pacific coast (pacific basin). this group inhabits a rural settlement and their subsistence system is based on agriculture, trade and fishing. nineteen dental casts were obtained from villarica (cauca municipality [inland]). this community is a new world african descendent population. their subsistence system is based on agriculture and sugar cane farming. their history is related to the distribution of african slaves in farms and sugar mills around the cauca valley region. these communities are isolated towns whose inhabitants are of african ancestry (> 90%) with low levels of admixture. another 56 dental casts were obtained from the amerindian group guambiano that inhabits the settlement of silvia in the department of cauca, colombia. silvia is a rural settlement characteristic of the highland amerindian populations of the south american andes. guambiano language belongs to coconucan-barbacoan family, which belongs to the chibchan-paezan or macro-chibchan family characteristic of highlands of colombian southwest and ecuador (ethnolgue, 2001). their subsistence system is based on agricultural activities. interestingly, according to their mating customs, we expect low rates of european and/or african admixture (pachón, 1996). the last 57 dental casts were obtained from individuals from popayán city. this group is known as “mestizo” (i.e., genetically admixed). latin american urban populations like popayán are usually trihybrid (sans, 2000), with a gene pool composed of varying frequencies of european and native-american genes, although some african admixture is also expected. the age and sex of each individual was recorded at the time of casting. the greatest portion of subjects examined in this study are children between 3 and 11 years of age. only teeth unaffected by wear, pathology, or casting error were included in the analyses. the individual count method was used to record the incidence of trait absence contrasted with all degrees of trait expression (scott, 1980). nonmetric traits thirty-seven deciduous crown nonmetric traits (19 maxillary and 18 mandibular) were scored following suggestions from several authors (hanihara, 1961, 1963; sciulli, 1998; grine, 1986; turner et al., 1991; sasaki and kanazawa, 1998). for among-group comparisons, dental data from 16 ancient and contemporary groups with various ethnic ancestries were gathered from the table 1. sex distribution and sample size of the contemporary colombian ethnic groups analyzed* guambiano african americans african americans amerindians admixed/mestizo (guapi) (villarica) (silvia) (popayán) m f t m f t m f t m f t 32 36 68 10 9 19 30 26 56 29 28 57 47.1% 52.9% 100% 52.6% 47.4% 100% 53.6% 46.4% 100% 50.8% 49.2% 100% *codes are males (m), females, and total (t) fig. 1. map of colombia showing the geographic location of the populations studied: 1 guapi, 2 villarica, 3 popayán, and 4 silvia. the scale is in kilometers. m.e. delgado-burbano 35 table 2. dental samples used for population comparisons sample area cultural sample code name area affiliation period size citation 1 japan japanese japan asiatic contemporary 183 hanihara, 1963, 1968, 1965 2 arc prehistoric ohio late amerindian valley archaic 3200-2700 bp 64 sciulli, 1990, 1998 , 3 wood prehistoric ohio woodland amerindian valley e-m-l 2700-1000 bp 34 sciulli, 1990, 1998 4 pear prehistoric ohio late prehistoric amerindian valley pearson/anderson 1000-350 bp 61 sciulli, 1990, 1998 5 sunw prehistoric ohio late prehistoric amerindian valley sun watch 1000-350 bp 76 sciulli, 1990, 1998 , 6 mono prehistoric ohio amerindian valley monongahela 1000-350 bp 62 sciulli 1990, 1998 7 buff prehistoric ohio late amerindian valley prehistoric buffalo 1000-350 bp 73 sciulli, 1990, 1998 8 pima contemporary arizona pima amerindian so. arizona contemporary 100 tocheri, 2002 9 safr south south natal nguni contemporary 53 grine, 1986 africans africa cape nguni prehistoric 10 wafr west african contemporary 18 lease 2003 11 afm.wash african washington african contemporary 249 hanihara, 1963, american usa american 1965 12 afm.mem african memphis african american tennessee american contemporary 117 lease, 2003 13 afm.dall african dallas, african contemporary 101 lease, 2003 american texas american 14 england english london european contemporary 86 lease, 2003 15 eua.usa no. american cleveland, european cnotemporary 100 lease, 2003 white ohio americans 16 india prehistoric india west inamgaon calcolithic 45 lukacs, walimbe, india 1600-700 bc 1984 literature, and these are listed in table 2. information regarding analyzed dental traits, break points, and frequencies in colombian groups are presented in tables 3 and 4. of the total traits analyzed, 18 were used for group comparisons in the multivariate analysis (table 5). statistical analyses the first step in the statistical analysis was testing dental trait frequency differences between males and females. this procedure was done by means of the pearson chi-square test to detect significance (p < 0.05). the next step was to obtain phenetic relatedness between samples using a multivariate analysis of principal components (pca) using spss 14.0 software. despite the numerous methods available for population comparisons using dichotomous data such as b-squared distance, correspondence analysis, pseudo-mahalanobis’ d², euclidean distance, average taxonomic distances, among others, anthropologists have focused almost deciduous variation in colombia 36 t a b l e 3 . m ax il la ry d ec id u ou s tr ai t fr eq u en ci es in fo u r co n te m po ra ry c ol om bi an p op u la ti on s g u ap i v il la ri ca si lv ia p op ay an tr ai t d ic h ot om ie s n k % n k % n k % n k % c it at io n sh ov el u i1 23/ 03 20 2 10 .0 2 0 0. 0 17 16 94 .1 11 4 36 . 6 h an ih ar a, 1 96 3 sh ov el u i2 23/ 03 36 3 8. 3 7 0 0. 0 24 22 91 .6 15 7 46 .6 h an ih ar a, 1 96 3 sh ov el u c 23/ 03 60 5 8. 3 18 0 0. 0 50 39 78 .0 46 15 32 .2 h an ih ar a, 1 96 3 d ou bl e sh ov el u i1 13/ 03 21 0 0. 0 2 0 0. 0 17 0 0. 0 11 0 0. 0 sc iu ll i, 19 98 d ou bl e sh ov el u i2 13/ 03 36 0 0. 0 7 0 0. 0 24 0 0. 0 14 1 7. 1 sc iu ll i, 19 98 d ou bl e sh ov el u c 13/ 03 60 3 5. 0 18 2 11 .1 51 1 2. 0 41 4 8. 5 sc iu ll i, 19 98 w in gi n g u i1 12/ 03 22 2 10 .0 2 0 0. 0 17 5 29 .4 11 6 54 .5 d ah lb er g, 1 96 3 in te rr u p ti on gr oo v es u i1 14/ 04 21 0 0. 0 1 0 0. 0 17 0 0. 0 11 0 0. 0 sc iu ll i , 19 98 , t u rn er et a l., 1 99 1 in te rr u p ti on gr oo v es u i2 14/ 04 36 2 5. 5 6 0 0. 0 21 0 0. 0 14 1 7. 1 sc iu ll i, 19 98 , t u rn er et a l., 1 99 1 tu be rc u lu m d en ta le u i1 14/ 04 20 4 20 .0 2 0 0. 0 17 6 35 .2 11 1 9. 0 g ri n e, 1 98 6 tu be rc u lu m d en ta le u i2 14/ 04 35 6 17 .1 6 0 0. 0 22 9 41 .0 14 3 21 .4 g ri n e, 1 98 6 tu be rc u lu m d en ta le u c 14/ 04 60 48 80 .0 18 11 61 .1 53 42 79 .2 47 29 61 .7 g ri n e, 1 98 6 m es ia l r id ge u c a su 1 -3 59 8 13 .5 18 0 0. 0 52 11 21 .1 47 6 12 .7 tu rn er e t al ., 19 91 d is ta l a cc es so ry ri d ge u c 14/ 04 57 33 57 .9 18 4 22 .2 48 14 29 .1 40 11 27 .5 sc iu ll i, 19 98 , tu rn er e t al ., 19 91 h yp oc on e u m 1 4+ 4/ 24 60 19 31 .6 12 2 16 .6 47 0 0. 0 41 12 29 .2 h an ih ar a, 1 96 3 h yp oc on e u m 2 4+ 4/ 34 68 67 98 .5 18 18 10 0. 0 55 55 10 0. 0 50 49 98 .0 h an ih ar a, 1 96 3 m et ac on e u m 2 a su 1 -5 68 68 10 0. 0 17 16 94 .1 56 56 10 0. 0 49 49 10 0. 0 tu rn er e t al ., 19 91 m et ac on u le u m 2 a su 1 -5 67 13 19 .4 18 5 27 .7 56 3 5. 3 47 5 10 .6 tu rn er e t al ., 19 91 c ar ra be ll i’ s u m 2 24/ 04 68 26 38 .2 16 10 62 .5 56 39 69 .6 49 20 40 .8 g ri n e, 1 98 6 m.e. delgado-burbano 37deciduous variation in colombia t a b l e 4 . m an di bu la r de ci du ou s tr ai t fr eq u en ci es in fo u r co n te m po ra ry c ol om bi an p op u la ti on s g u ap i v il la ri ca si lv ia p op ay an tr ai t d ic h ot om ie s n k % n k % n k % n k % c it at io n d ou bl e te et h li 1 1 12 0 0. 0 2 0 0. 0 4 0 0. 0 3 0 0. 0 sc iu ll i, 19 98 sh ov el li 1 23/ 03 10 0 0. 0 2 0 0. 0 8 8 10 0. 0 4 0 0. 0 h an ih ar a, 1 96 3 sh ov el li 2 23/ 03 11 0 0. 0 3 0 0. 0 12 11 91 .6 12 7 58 .3 h an ih ar a, 1 96 3 tu be rc u lu m d en ta le lc 14/ 04 52 22 42 .3 15 0 0. 0 45 1 2. 2 44 4 9. 0 g ri n e, 1 98 6 d is ta l a cc es so ry ri d ge lc 14/ 04 51 31 60 .7 13 3 23 .0 42 13 31 .0 39 9 23 .0 sc iu ll i, 19 98 , tu rn er e t al ., 19 91 c u sp n u m be r lm 2 58/ 28 65 65 10 0. 0 16 16 10 0. 0 50 50 10 0. 0 43 43 10 0. 0 sc iu ll i, 19 98 g ro ov e p at te rn lm 2 y / + -x -y 65 63 97 .0 15 15 10 0. 0 50 50 10 0. 0 42 41 97 .6 sc iu ll i, 19 98 d efl ec ti n g w ri n kl e lm 2 1 65 34 52 .3 15 7 46 .6 46 35 76 .0 42 19 45 .2 sc iu ll i, 19 98 p ro to st yl id lm 2 12/ 02 65 17 26 .1 17 3 17 .6 53 28 52 .8 43 25 58 .1 g ri n e, 1 98 6 m es io bu ca l gr oo v e lm 2 13/ 03 66 66 10 0. 0 17 16 94 .0 52 52 10 0. 0 43 41 95 .0 g ri n e, 1 98 6 d is ta l t ri go n id cr es t lm 1 12/ 02 59 2 3. 3 14 1 7. 1 39 1 2. 5 40 1 2. 5 sa sa ki , k an az aw a, 1 99 8 d is ta l t ri go n id cr es t lm 2 a su 1 -5 66 21 34 .4 16 4 25 .0 48 17 35 .4 42 6 14 .2 tu rn er e t al ., 19 91 m ed ia l t ri go n id cr es t lm 1 12/ 02 60 57 95 .0 14 13 93 .0 38 32 84 .2 40 38 95 .0 sa sa ki , k an az aw a, 1 99 8 m ed ia l t ri go n id cr es t lm 2 12/ 02 65 13 20 .0 15 2 13 .3 48 4 8. 3 42 2 4. 7 sa sa ki , k an az aw a, 1 99 8 d el ta f or m lm 1 1 58 0 0. 0 12 0 0. 0 41 0 0. 0 39 0 0. 0 sc iu ll i, 19 98 c u sp 5 lm 2 a su 1 -5 65 64 98 .4 15 15 10 0. 0 50 50 10 0. 0 43 43 10 0. 0 tu rn er e t al ., 19 91 c u p s 6 lm 2 14/ 04 65 8 12 .3 15 3 20 .0 50 30 60 .0 40 13 32 .5 to w se n d e t al ., 19 90 c u sp 7 lm 2 13/ 03 65 28 43 .0 15 6 40 .0 49 4 8. 1 41 11 26 .8 h an ih ar a an d m in am id at e, 1 96 5 38 m.e. delgado-burbano fig. 2. scatterplot of the first two components based on frequencies of traits in the deciduous dentition. a total of 20 samples are plotted. axis 1 and 2 account for 50% of total variance (28.1% along x-axis and 21.5% along y-axis). for codes and references see tables 1 and 2. the ellipse includes the four colombian samples studied. fig. 3. correlation coefficients (loadings) distribution in the three first principal components for 18 dental nonmetric traits between 20 populations of different ancestry with deciduous dentition. accounts for 66.1% of total variance (28.1% pc1, 21.5% pc2, and 16.5% pc3). 39 exclusively on the use of c. a. b. smith’s mean measure of divergence (mmd) based on the distance concept or the degree of dissimilarity between samples (e.g., irish, 1993; scott and turner, 1997). the power of other analytic methods in the assessment of population affinities such as pca has not been totally explored. the variables submitted to pca (trait frequencies) are parametric (ratio scale), and frequencies of nonmetric traits can be used to produce numerically derived population relationships. recent studies employed pca to assess population affinities using discontinuous dental traits with good results (cucina et al., 2003; coppa et al., 2001; irish and guatelli-steinberg, 2003; stringer, 2002; delgadoburbano, 2007). in fact, irish and guatelli-steinberg (2003) and coppa et al. (2007) compare pca in great detail with other methods; in their case with statistics of distance as mmd, and they found very similar results, suggesting the reliability of pca in the study of human population affinities using nonmetric traits. the main benefit of pca is that the reduced, conceptually more coherent, set of components is often easier to comprehend than the larger collection of potentially correlated variables (irish and guatellisteinberg, 2003). however, the key reason for using pca in the present study is that the correlations computed between original variables and components identify those dental traits that are most responsible for intersample variation. only components with an eigenvalue higher than 1.0 were taken into account. those correlation coefficients between a variable and the component that were higher than 0.6 were considered pertinent (alfredo coppa, personal communication, 2007). the inter-group relationships based on the first two components—which contain much of the total variance—were plotted to discern relationships among samples via scatterplots produced by the graph function of spss 14.0. results the colombian ethnic groups analyzed here did not exhibit significant sexual dimorphism in deciduous nonmetric traits. two exceptions are for the mestizo sample that exhibited two dental traits with significant male-female differences, namely bushman canine uc (p = 0.037; 2 df) and carabelli tubercle um1 (p = 0.028; 2 df). irish (1993) suggested that dental traits exhibiting significant sexual dimorphism of less than 10% do not affect the population relationships. these traits only represent 5.4% (i.e., 2 of 37) and, accordingly, were not removed from the analysis. subsequently, sexes were combined for the study of intergroup affinities. intergroup relationships are presented in fig. 2. the pca data for dental variants are presented in table 5, which show the component loadings, eigenvalues, and percentages of variance explained by the dental traits. fig. 3 depicts the significant correlation coefficients from among the 18 dental traits based on the pca. pca yielded three components that collectively account for 66.1% of the total variance. in each component, 16 dental traits were identified with significant positive (> 0.6) and negative (> -0.6) correlation coefficients (loadings). in the first component (28% of total variance) six dental traits were identified, five with positive and one with negative loadings (table 5). high frequency dental traits with a positive correlation coefficient characterize all populations with asian-sinodont ancestry. in fact, north and south native american samples (both prehistoric and contemporary) and recent asians (japan) have high frequencies of these traits, which are ubiquitous in the “mongoloid dental complex” (hanihara, 1966). some other groups with non-asiatic ancestry also have high frequencies (african-colombian, south africans and mestizo). on the other hand, one trait with a negative significant correlation coefficient in the first component was also identified. this has middle to high frequencies in africans, african-americans from north and south america, european-americans and south asians (india) analyzed here. interestingly, all four colombian samples have high frequencies of these traits. their high frequency in african-colombians and mestizo groups is not surprising. however, colombian amerindians (guambianos) have the second highest frequency after south africans (based on the study by grine, 1986). this observation possibly reflects high rates of admixture with populations of african or european ancestry. in the second canonical axis (21.5% of total variance) six deciduous dental traits with positive significant correlation coefficients were identified. once again, these traits characterize asian-derived populations. shovel ui1 is in high frequency in recent japanese, prehistoric native north americans and contemporary colombian amerindians. recent north-american indians (pima) have intermediate frequencies. africanamericans from dallas and memphis (lease, 2003) have high frequencies, suggesting admixture with amerindians. this same pattern of biogeographic distribution is recognized for shovel shape in ui2, uc and li1. europeans, european americans and mestizo samples share middle to high frequencies. tuberculum dentale ui1 has high frequencies in african-colombians from guapi, european-americans and colombian amerindians. tuberculum dentale ui2 has similar frequencies in human groups with different ancestry; however, it showed a slight increase in native americans in general and in colombian mestizos. finally, the third canonical axis (16.5% of total variance) identified four dental traits with significant positive loadings, however their population distributions are totally disparate. the first two dental traits (distal accessory ridge in upper and lower canines) have high frequencies in african-colombians, west africans, prehistoric north american indians and recent colombian amerindians and mestizo. other deciduous variation in colombia 40 human groups studied here have low or mediumlow frequencies. the next two dental traits identified (hypocone um2 and groove pattern lm2) have very similar frequencies among human groups with different ethnic and biological ancestry. hypocone um2 occurs in very high frequencies in all samples, ranging from 77% to 100%. an exception is presented for europeanamericans (lease, 2003) who have very low frequency (36%). this finding is possibly related to selection pressures—or simply sampling fluctuation. it is notable that this finding also occurs in new world african derived groups from colombia (delgado-burbano, 2006). groove pattern lm2 has nearly identical (90-100%) frequencies across all dental samples, except european and african descendents from north america who have very low frequencies, which suggests intensive gene flow from ethnic groups of different ancestry. fig. 4 shows a comparison of the frequencies of those 16 dental traits most responsible for inter-group variation in the pc analysis (table 5) among four colombian samples analyzed. the fluctuations of dental trait frequencies reflect well the ancestry and microevolutionary dynamics between colombian groups. table 5 shows that dental traits with significant positive correlation coefficients in pc scores 1 and 2 characterize native americans and recent asian m.e. delgado-burbano populations (sinodonts) (but see loading of carabelli tubercle on pc1). conversely, pc score 3 distinguishes groups with african and european ancestry. however, this pattern is very dynamic since some asiandescendent samples have high frequencies of african and european dental traits and vice versa. in fact, fig. 2 and 4 demonstrate that all colombian groups have a relatively close biological relatedness to one another, as well as display a mixture of asian and european-african dental morphological characters. within the four colombian samples, tables 3-5 and fig. 4 show that african-colombians have high frequencies of distal accessory ridge uc, hypocone um2, carabelli tubercle um2 and groove pattern lm2. on the other hand, guambiano amerindians have very high frequencies of shoveling and double shoveling in upper and lower central and lateral incisors and canines. nonetheless this group has similar frequencies of the same dental traits that characterize african-colombians (fig. 4). mestizos have traits very similar to africanamericans and to amerindians, confirming their highly admixed gene pool. discussion ethnic groups of disparate ancestry are unevenly distributed around colombia, and their patterns of table 5. component loadings, eigenvalues and variances for dental nonmetric traits in 20 populations of different ancestry with deciduous dentition1 contribution of the components trait pc1 pc2 pc3 double shovel ui1 0.87 0.21 -0.01 double shovel ui2 0.79 0.13 0.07 cusp 5 um2 0.79 -0.02 0.21 double shovel uc 0.75 -0.04 0.21 carabelli um2 -0.72 0.04 0.24 deflecting wrinkled lm2 0.62 0.53 0.01 dental tubercle ui2 0.00 0.86 0.24 shovel ui1 0.45 0.78 -0.13 dental tubercle ui1 -0.15 0.78 0.12 shovel li2 0.55 0.70 0.10 shovel ui2 0.48 0.67 -0.31 shovel uc 0.59 0.60 -0.32 protostylid lm2 -0.17 0.39 0.24 distal accesrory ridge lc -0.13 0.04 0.87 groove pattern lm2 0.45 0.24 0.78 hypocone um2 0.01 0.04 0.71 distal accesory ridge uc 0.36 0.14 0.67 cusp number lm1 0.33 0.25 -0.40 eigenvalue 5.05 3.88 2.98 variance (%) 28.06 21.56 16.57 cumulative variance 28.06 49.62 66.19 1highlighted entries denote relatively high positive and negative loadings within that particular component. 41 admixture vary considerably between and within regions. some areas, such as northwestern colombia, were settled predominately by european males who admixed with native american females. other regions, such as the pacific basin, have appreciable african ancestry. on the other hand, the andean area is predominately amerindian. typically, neo-american societies were founded by populations with a high and medium maternal amerindian contribution and a substantial european paternal contribution. in some american regions, in addition, variable percentages of paternal and/or maternal african contributions are also evident (delgado-burbano, 2007). for instance, one can find “amerindian continental regions” (peru, mexico, bolivia, chile), “african continental regions” (brazil and some areas of colombia, venezuela and ecuador) and “european continental regions” (argentina, uruguay, northwestern colombia). the evolutionary dynamics of contemporary colombian populations have been analyzed almost exclusively by means of genetic markers (ruiz-linares et al., 1999; mesa et al., 2000; keyeux et al., 2002; rodas et al., 2003; carvajal-carmora et al., 2000; bedoya et al., 2006; briceño et al., 2003; melton et al., 2007; bortolini et al., 2004; salas et al., 2004, 2005). in consequence, little is known about the variation of morphological dental traits in these populations. the population affinity analysis carried out here (fig. 2) shows that guambiano amerindians have some affinities with prehistoric native north americans, but “close” affiliations with contemporary north american indians and recent northeast asians were not evident. recent molecular studies show close affinities between deciduous variation in colombia guambiano and other native american populations from the amazonas and orinoco basin (keyeux and usaquen, 2005)—in contrast to a lack of affinity with north and central american indigenous groups. interestingly, the present analysis also presents a more distant affinity with recent north american amerindians, which agrees with the above-mentioned mtdna analysis (keyeux et al., 2002). guambiano has predominately sinodont dental traits; however, its high frequency of carabelli tubercle possibly reflects european and/or african admixture. previous genetic analysis based on blood groups corroborate this finding, suggesting that guambiano-speaking people have 4.9% percent of african-descendent haplotypes as well as an unknown proportion of european admixture (yunis et al., 2001). this indigenous group is characterized by conservative mating customs and deep cultural roots (camacho, 1996). however, this dental study and genetic analyses show that their recent history underwent rather intensive gene flow from groups of different ancestry, specifically from mestizos and/or african-descendents. the sample of colombian hybrids (mestizos from popayán) analyzed here has a high amerindian and african component, while a european component is less evident. the history of popayán dates back to the 16th century when spanish conquerors founded this city. european male and criollo (spaniards born in american colonies) contributed substantially to the emergent population. traditional popayán inhabitants are culturally and phenotypically identified with their european ancestors. however, contrary to other colombian regions such as antioquia or bogotá, amerindian and african contributions are high. this fig. 4. comparisons of the frequencies of 16 deciduous dental nonmetric traits more important for inter-sample variation according to pca between four colombian samples. 42 m.e. delgado-burbano trend reflects the general situation where high rates of gene flow among very different ethnic groups occur in urban centers in many latin america countries (sans, 2000). rodas et al. (2003); carvajal-carmora et al. (2000) and bedoya et al. (2006) previously showed that other colombian mestizo populations also have a high amerindian component, but without a corresponding european or african contribution. the proportions of admixture for northwestern colombian region of antioquia are as follows: 94% european, 5% african and 1% amerindian (y-chromosome data) and 2% european, 8% african and 90% amerindian (mtdna data) (carvajal-carmora et al., 2000; bedoya et al., 2006). mestizos from bogotá have 78% percent of amerindian lineages (a = 37.4 and b = 26.4%) and 22% of european lineages (16.5% of h, t, u v, w and 2.2% of j or k or african haplotypes) (rodas et al., 2003). the present dental analysis disagrees with these genetic studies since it suggests high african admixture and very low levels of gene flow from europeans. this finding is interesting because popayán inhabitants have a predominantly “european” cultural identity. however, this situation may be different in other colombian regions. little is known about the microevolution and diversification of africans and their descendents in colombia. only in the last decade have africancolombians been studied from a genetic point of view (rodas et al., 2003; keyeux, 1993; keyeux et al., 2000; bortolini et al., 2004; salas et al., 2004, 2005). traditionally, historical and anthropological studies have shown clear cultural, linguistic, and religious similarities among afro-colombians and western african bantu-speakers (schwengler, 1992; colmenares, 1997; del castillo, 1982). previous dental studies show that african-colombians have close biological affinities with sub-saharan africans (delgado-burbano, 2006, 2007). specifically, samples from western and central africa such gabon, congo pygmy, nigeria, cameroon, togo and benin display dental morphological similarities with afrocolombians. this dental relatedness has been confirmed by mtdna studies as well as historical records (rodas et al., 2003; keyeux et al., 2000; salas et al., 2004, 2005; bortolini et al., 2004; del castillo, 1982). additionally, these dental studies show unexpected population relationships between african-colombians and eastern (kenya and tanzania) and southeastern africans (south-africa). in fact, these regions played a very important role in the importation of african slaves to colombia—more than previously assumed. as salas et al. (2005:857) pointed out: “there is also some indication of a mozambican component in african-americans of the colombian pacific coast [i.e. chocó] represented by the characteristic south eastern african mtdna haplogroup founder l0a2 and moreover the l3e1* type present is typically southeast african.” interestingly, the landscape of genetic relatedness of african-colombians and other south-africanamericans are almost identical to the affinities displayed by dental nonmetric data. dental information of african-colombian samples analyzed here is consistent with previous dental analysis (delgado-burbano, 2006, 2007). guapi and villarica populations show close relationships with western africa. although a close relationship with south africa is not evident, the pattern of phenotypic affinities of african-colombians suggests that sub-saharan africa, specially western, eastern and southeastern africa are important origin regions. fig. 2 shows that african-american colombian samples have clear affinities with african-americans from washington but not with african-americans from memphis and dallas (comparative data from lease, 2003). this finding could suggest both different ethnic origins of african-american populations in the americas and/or distinct microevolutionary histories. previous dental analyses (lease, 2003; delgadoburbano, 2007) show that north-african-americans have close affinities with european-americans due to intensive gene flow that modified their gene pools and therefore their biological associations with other africandescendent populations and their african ancestors. rodas et al. (2003) based mtdna haplogroup analysis shows asymmetrical patterns of admixture in africancolombians that disagree with the present study. several samples from the pacific basin have medium and high admixture with native americans. specifically a significant proportion of amerindian lineages a (mean frequency: 8.2%) and b (mean frequency: 10.6%) were detected. although frequencies of incisor shoveling and deflecting wrinkle in guapi and villarica possibly indicate the presence of a native american component in their gene pool, population affinities shown in fig. 2 and dental frequencies presented in fig. 4 imply a low rate of admixture between colombian native americans and african-descendents, in agreement with more recent mtdna analysis (salas et al., 2004, 2005). in conclusion, colombian samples analyzed here present a complex history, where gene flow probably was the main factor configuring the contemporary gene pools. although some samples show disparate ancestries in their dental morphology (i.e., mestizo), other groups (african-colombians and amerindians) appear to share close relationships with their sister and parental populations. patterns of phenotypic diversity of these colombian groups probably parallel those that have occurred in other latin-american populations in similar historical contexts. acknowledgments i thank the colombian communities that participated in this study; without their help it would not have been possible. this study was partially supported by a grant of the colombian institute for the development of 43deciduous variation in colombia science and technology colciencias (1103-04-11985) and antropos and antropacifico research groups of the department of anthropology, university of cauca, colombia. thanks to alexandra delgado for grammatical editing of the manuscript. thanks to dr. javier rosique (department of anthropology, antioquia university, colombia) for his useful comments and assistance. literature cited bedoya g, montoya p, 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are usually associated with the complex morphology of teeth that can make it impossible to scan parts of a surface from some directions or lead to with difficulties in defining appropriate reference points and planes. in some cases “internal” reference points (i.e., anatomical features or prepared reference markers) are defined and scanning can extend either to a limit defined by another reference point or a predetermined distance. alternatively, in some studies appropriate “external” reference points (eg points on the specimen mount) can be defined. this paper describes the application of widely available hardware and software packages to provide an affordable system for acquiring 3d coordinates from the surface of a dental crown and subsequently for comparing three-dimensional data derived from these coordinates. as part of the development process, the system was validated by comparison of calculated data with the known dimensions and volumes of standard objects. the reproducibility of the derived data, both within and between observers, was also determined from repeated measurements. to illustrate the application of the system, we have measured the loss of tooth occurring during simulated tooth wear. however, the software and hardware have a system for the acquisition and analysis of three-dimensional data describing dental morphology pingzhou liu, sarbin ranjitkar, john a. kaidonis, grant c. townsend, and lindsay c. richards* dental school, faculty of health sciences, the university of adelaide *correspondence to: lindsay richards, dental school, faculty of health sciences, the university of adelaide, adelaide 5005, south australia e-mail: lindsay.richards@adelaide.edu.au abstract: accurate, reproducible three-dimensional (3d) data provide an important contribution to our ability to describe, compare and understand dental morphology but the existing technology is often expensive or has technical limitations. recently available, inexpensive 3d profilometers interfaced with standard personal computers offer the potential to overcome some of these problems. this technical note describes a system that uses a 3d profilometer and purpose written software to analyse changes in dental morphology resulting from tooth wear. the validity of the derived data was determined by comparing data derived from scans of objects of known dimensions with calculated volumes. these differences were less than 10% from objects that were difficult to scan because of their geometry and were commonly less than 5%. the reproductibility, expressed as intraand inter-observer coefficients of variation, was less than 1%. the potential applications of systems of this type are outlined. dental anthropology 2004;17(3):70-74. the flexibility to provide valid, reproducible data in a broad range of studies of morphology. materials and methods for data acquisition a 3d scanner (pix-4, roland dg, tokyo, japan) interfaced with a personal computer was used to record the heights (z) of surface mesh points (x and y). in this system an active piezo sensor detects contact between its stylus and the scanned surface (fig. 1). the x and y mesh steps can be set between 50µ and 5.00 mm in 50µ steps and the z-axis direction has a resolution of 25µ. the “dr.picza” software (roland dg, tokyo, japan) provided with the scanner is a windows or mac osx-based tool that allows the scan area to be defined to accommodate the dimensions of the specimen and the scanning resolution to be set according to the user’s needs. this decision involves balancing the need for high resolution against the size of the resultant data set and the scanning duration, both of which are increased with increasing resolution. in addition, a lower limit and the approximate x and y coordinates of the highest point of the specimen can be defined to further optimise the size of the data set and shorten the scanner’s calibration and scanning times. the software allows basic manipulation and visualization of the data (fig. 2) and has the facility to export data in a range of 70 71 formats for subsequent analysis. in our example, we were aiming to measure the changes in dental crown volume resulting from simulated tooth wear. we therefore mounted our specimens (in this case either the buccal of lingual halves of human tooth crowns) with three reference markers (2 mm diameter titanium spheres) equally spaced around the specimen. after each period of simulated wear the specimen was re-scanned and the volume of the crown above the reference plane compared with previous volumes. because the predicted changes were relatively small (expected to be of the order of 20 mm3) we chose the highest scanning resolution (i.e., 50µ for the x and y matrix and 25µ for the height (z)). the derived data set was exported as a text file for detailed analysis. for data analysis, a purpose-written software package was developed using matlab (version 6, the mathworks inc, natick ma, u.s.a.). the package accepts data from “dr picza” in the form of (x, y, z) triples, where the x values are the west-east coordinates and the y values the north-south coordinates. to make optimum use of matlab and its graphic facilities, we converted the data set to a regular mesh grid and saved the z-values to a matrix (z). the menu-driven software package then provides a series of options for defining the reference plane, graphing the data in 3d and deriving data describing the volume of the scanned object and the surface area and the height of the highest point on the object from the reference plane in cases where this is of interest. in our example, we needed to find the volume bounded by two surfaces: the tooth surface and a planar surface defined by the three external reference points. the data transferred from dr picza were plotted using the matlab routines and the maximum heights of source sum squares d.f. mean square f-ratio p-value repeated measures 8.7303 9 0.97003 37.89 <0.001 observers 0.0287 2 0.01437 0.56 0.5803 scans 0.0003 1 0.00026 0.01 0.9214 repeat-x-observer 0.8173 18 0.04541 1.77 0.1169 repeat-x-scan 0.1028 9 0.01143 0.45 0.8914 observer-x-scan 0.1011 2 0.05054 1.97 0.1678 error 0.4608 18 0.02560 total 10.2414 59 table 1. three-way analysis of variance comparing 10 repeated measures from two scans of a single specimen performed by three independent observers fig. 1. scanner with specimen mounted on scanning table. fig. 2. data visualization and co-ordinate display from “dr picza” software. three-dimensional data acquisition 72 73 the three reference points were identified (fig. 3). the volume of the part of the specimen above the reference plane was calculated. because 3d objects can on occasions include undercut areas, the package has an option to allow the reference plane to the re-aligned so that the calculations do not include parts of the specimen for which there are no data. in our example this was undertaken by selecting the appropriate option from the menu, inspecting the graphical display and deciding on an appropriate realignment to avoid the undercut and recalculating the data (fig. 4). to establish the validity of the data obtained, objects of know dimensions were scanned and the calculated volumes compared with the volumes derived from the scanner data. to establish the reproducibility of the method, intraobserver variation was assessed by repeated analysis by one observer (pz) and inter-observer variation was determined by comparing data derived by different fig. 3. data plot and reference plane identification using purpose-written software. fig. 4. example of menu-driven adjustment to reference plane height to avoid undercut areas on specimen. congratulations! your measurement of newtest11 is done. ------------------------------------------matrix: distance*, surface*, volume b = 0.7130 2.4011 7.6169 does the object have undercut areas (y/n)? y please give lift value of the referenceplane, which you can estimate from the contour diagram you have drawn. lift value = 1.012 max distance of the remnant to reference plane is: 0.7130 mm the convex surface area of the remnant is: 2.4011 mm^2 the volume of the remnant is: 7.6169 mm^3 if you want to see the 3-d picture of the original object and reference plane together, please press ‘y’, otherwise just press <enter>. selection (y/n): y p. liu et al. 72 73 observers. results scanning a relatively simple object (for example, a hemisphere of diameter 18.0 mm) gave a volume of 1583.27 mm3 compared with a calculated volume of 1526.81 mm3. the difference (56.45 mm3) represents 3.7% of the true volume. a smaller, more complex object (the small cylindrical projection on a lego® building block which has parallel sides and hence can have small undercut areas if the block is not mounted exactly horizontally) had a theoretical volume of 32.66 mm3 and a volume derived from the scanning data of 35.45 mm3 representing a difference of 8.5%. the intra-observer variation in calculated volume was small with the coefficient of variation (100 x standard deviation/mean) being 0.90% for the most experienced observer and 0.91% for the least experienced observer. to determine whether inter-observer variation or differences between repeated scans of the same object contributed significantly to the observed variation in repeated measures, one specimen was scanned on two occasions and each of these scans was analysed 10 times by three independent observers. a three-way analysis of variance (table 1) revealed no significant variation between observers (p=0.58) or between repeated scans (p = 0.92) and no significant interaction between any of the considered factors suggesting that the performance of experienced and inexperienced observers was similar. in our study of tooth wear the buccal surface of an extracted human tooth was subjected to 7000 cycles at the rate of 80 cycles per minute under a load of 3.2 kg with water at ph 7 used as a lubricant in an electromechanical tooth wear machine (kaidonis et al., 1998) to produce a wear facet (fig. 5a). the specimen was scanned and the volume of the dental crown above the plane defined by the three 2mm diameter ball markers that were used as “external” reference points was calculated. this was compared with volume of the specimen after it had been subjected to a further 105,000 cycles of wear (fig. 5b). the volume of enamel lost due to wear during this experiment (21.85 mm3) was calculated by comparing the first volume (149.74 mm3) with the final volume (127.89 mm3). discussion based on our assessment of the validity and reproducibility of the measurements derived using this system, we believe that it provides an affordable and reliable method for the acquisition of 3d data for the comparison of dental morphology. like most systems it is limited in its ability to deal with undercut areas that makes it important to carefully select the initial orientation of the specimen and define an appropriate reference plane to avoid undercuts. also, the acquisition of data from larger specimens at the highest resolution can be time consuming with high resolution scanning of a whole dental arch taking up to 30 or more hours. the costs involved in setting up the system are relatively small compared with some other systems. if a suitable personal computer and a licensed copy of the matlab package are available then the total hardware fig. 5. (left) data plot for specimen after 7,000 cycles of wear. (right) data plot for specimen after 112,000 cycles of wear. three-dimensional data acquisition 74 75 set up cost should be less than $us 1,200 compared with more than $us 100,000 for some commercial laser-based systems. the purpose-written matlab-based software package is available on request from the authors. the validity of the data derived using the system was established by comparing volumes derived by scanning with the calculated volumes of objects of known dimensions. this indicated that calculated and scan-derived volumes differed by between 3.7 percent and 8.5 percent depending on the size and geometry of the specimen. interpreting this information was complex for a number of reasons. in the case of the sphere (a computer-mouse ball), the difference between the scanned and calculated volumes was relatively small and challenged our ability to accurately measure the ball. a difference in radius of the ball of the order of 0.1 mm would result in a difference in volume of more than 3.4% and made it difficult to determine which of the calculated and scan-derived data was the more valid. in the case of the lego® building block the differences were larger because the object presented some obvious and some hidden challenges and represented a “worst case” in terms of the ability of the system to derive valid data. the obvious challenge was the geometry of the object that, with its parallel sides, required precise orientation to avoid undercuts. in addition, the curvefitting procedures that were used to define the surface were not ideally suited to objects of this type. the hidden challenge was the surface morphology of the object. the face of the projection on the block included the manufacturer’s trademark etched into the surface. this was not obvious on observation and therefore not included in the calculations but was obvious on the enlarged scan and would contribute to the difference between the calculated and scan-derived volumes. the reproducibility of the data was assessed by repeated measures of a test specimen by different observers. the intraand inter-observer errors were all small with coefficients of variation for repeated measures being less than 1.0% for all scans and observers, and with no significant differences between observers or repeated scans. based on our experience, we believe that the system described is an affordable, valid and reliable method for obtaining 3d data for the description and comparison of dental morphology. acknowledgments the support of the national health and medical research council of australia and the assistance of dr shosei eguchi, nihon university school of dentistry at matsudo, japan and heather lewis are acknowledged. literature cited delong r, pintado m, douglas wh. 1985. measurement of change in surface contour by computer graphics. dental materials 1:27-30 hewlett er, orro me, clark gt. 1992. accuracy testing of three dimensional digitizing systems. dental materials 8:49-53 kaidonis ja, townsend gc, richards lc, tansley gd. 1998. wear of human enamel: a quantitative in vitro assessment. j dent res 77:1983-1990 mcdowell gc, bloem tj, lang br, asgar k. 1988. in vivo wear. part 1: the michigan computer graphic measuring system. j prosthet dent 60:112-120 roylet jf, reich t, lutz f. 1983. high precision occlusal mapping: a new method for measuring wear of posterior composites. j dent res 62:220 (abstract). p. liu et al. al-abbasi and sarie 1997.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg brace.3 pg14.jpg pg15.jpg pg16.jpg kelley and gillerin 1986.1 pg5.jpg pg6.jpg tihacek-sojic and djuric-srejic 1998.5 pg14.jpg pg15.jpg pg16.jpg pg17.jpg pg18.jpg pg19.jpg pg20.jpg lauc 2003.1 65 1951). a polygenetic model was suggested after phenotypes were compared with the expected hardy-weinberg distribution (goose and lee, 1971). the trait occurs mostly bilaterally with symmetrically expressed grades (alvesalo et al., 1975; thomas et al., 1986; laatikainen and ranta, 1996), and, in asymmetric situations, no directional asymmetry has been detected (townsend and martin, 1992). these same authors suggest a genetic basis for the fluctuating trait asymmetry as a consequence of developmental instability, namely the degree of individuals’ heterozygosity in the population (townsend and martin, 1992). hence, it should be of interest to analyze a population with high homozygosity and to compare the phenotypic trait distributions and the degree of trait symmetry among its subpopulations defined by degree of homozygosity. the carabelli trait is a well-known morphological feature positioned at the mesiolingual surface of maxillary molars and the trait is expressed along a continuum of a wide range of pits, crescents, grooves and cusps. carabelli’s trait is most commonly observed in european populations where frequencies vary from 50% to 90% (laatikanen and ranta, 1996). kiesser and van der merwe (1984) evaluated the classificatory reliability of four grading systems that have been described in the literature, showing dahlberg’s eight-grade classification to be the most confidently applied. in general, carabelli traits can be divided into two main groups: positive features (protuberance and cuspform structures) and negative features (furrow and pitform structures), with few morphological variations in both groups (alvesalo et al., 1975; townsend and brown, 1981; laatikanen and ranta, 1996). this classification commonly has been used in interpopulation analyses (alvesalo et al., 1975). although most authors agree that the carabelli trait is genetically determined, the basis of inheritance is still not clear. some twins studies suggest that the heritability of the trait is low (biggerstaff, 1973; alvesallo et al., 1975; scott and potter, 1984), whereas other results suggest high heritability (škrinjarić, 1985; townsend and martin, 1992). early studies proposed a single-gene, autosomal dominant genetic model (dietz, 1944) and an intermediate two-allele mode of inheritance (kraus, influence of inbreeding on the carabelli trait in a human isolate tomislav lauc* institute for anthropological research, 10000 zagreb, croatia *address for correspondence: tomislav lauc, institute for anthropological research, amruševa 8, 10000 zagreb, croatia e-mail: tom@inantro.hr abstract the purpose of this study is to evaluate the influence of increased homozygosity due to inbreeding on the phenotypic distribution of the carabelli trait. the sample consisted of 224 dental casts representing 20.2% of the total children aged 7 to 14 years from the endogamous, inbred population of the island of hvar, croatia. inbreeding analysis compared the children with different rates of grandparental endogamy relative to the expression of carabelli’s trait. the design evaluated the effect of inbreeding on carabelli trait on the maxillary permanent first molar within a natural setting of reduced variability of environmental factors. very high frequency of the carabelli trait was observed for the permanent first molar on both sides of the arcade (84% and 86% on left and right sides). significant difference among the groups who have different degrees of inbreeding was found when carabelli trait was divided into absent, negative features, and a positive cusp using dahlberg’s grading system. it seems that carabelli’s trait is strongly genetically determined, and present findings imply it may be controlled byrecessive alleles. if heterogeneous polygenic developmental modules are responsible for the diversity of carabelli’s trait, they stay relatively stable after initiation of the developmental process when it appears that other environmental factors have no measurable effect. dental anthropology 2003;16(3):65-72. editor’s note: mr. lauc’s paper was awarded first prize for 2002 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. tomislav lauc 66 67 an appropriate data set for such analysis is a wellinvestigated population divided into subpopulations that share similar environmental conditions. during 30 years of continuous interdisciplinary investigation of the rural population of the adriatic island of hvar different biomedical, sociocultural, biocultural, genetic and orofacial traits have been studied (rudan, 1972; rudan et al., 1982a,b, 1986; roguljić et al., 1997; janićijević, 1994; smolej, 1987; sujoldžić, 1997; šimić and rudan, 1990; šimić et al., 1992; martinović et al., 1998; waddle et al., 1998). population structure studies (roguljić et al., 1997; rudan et al. 1990) indicate notably high levels of inbreeding, endogamy, and isonymous marriages (marriages between individuals sharing the same surname) on this island, thus identifying the population of hvar as one of the last genetic isolates in europe. such a population is an interesting model for orofacial genetic analyses because the main genetic consequence of inbreeding is to increase the proportion of homozygotes in the population (bodmer and cavalli-sforza, 1976). if some recessive genes are responsible for phenotypic trait expression, prevalence of such expression is expected to be higher in an inbred than in the general population. therefore, the aim of this study was to evaluate the influence of elevated homozygosity on the phenotypic distribution of carabelli’s trait on the permanent first molar. materials and methods the material for this investigation consisted of 224 dental casts of children aged 7 to 14 years from all elementary schools on the island of hvar, croatia (tables 1 and 2). the sample was targeted, matched for age and sex distribution to the total elementary school population of the island, and the sample covered 20.2% of the total cohort. the pupils’ parents provided complete two-generation genealogical data for each examined child (i.e., parents and grandparents with the place of residence of each individual). table 1 presents the distribution of the sample according to sex, age, birthplace, and grandparental endogamy. dahlberg’s classification was used with the following gradations: (0) smooth mesiobuccal crown surface; (1) small vertical ridge and groove; (2) small pit with minor grooves diverging from depression; (3) double vertical ridges or slight and incomplete cusp outline; (4) y-form (i.e., moderate grooves curving occlusally in opposite directions); (5) small tubercle; (6) broad cusp outline with a moderate tubercle, and (7) large tubercle with a free apex (kieser and van der merwe, 1984). in dahlberg’s classification, four grades (1 through 4) can be termed negative and three grades (5 through 7) positive trait forms. asymmetry was expressed in terms of the proportion of individuals showing differences bet. lauc sampled proportion age (years) total children sample of the total children n % n % % 7 129 11.6 27 12.0 20.9 8 153 13.8 34 15.2 22.2 9 125 11.3 28 12.5 22.4 10 117 10.6 21 9.4 17.9 11 143 12.9 26 11.6 18.2 12 136 12.3 27 12.1 19.9 13 168 15.1 28 12.5 16.7 14 138 12.4 33 14.7 23.9 total 1109 100.0 224 100.0 20.2 table 1. age distribution of the sample inhabitances on island under 15 years of age sample size location males females total males females total towns 766 711 1477 69.6% 86 68 154 68.8% villages 339 305 644 30.4% 40 30 70 31.2% total 1105 1016 2121 126 98 224 52.1 47.9% 56.3% 43.7% table 2. sex and demographic distribution1 1there are three towns on the island of hvar: hvar, starigrad and jelsa. these towns are administrative centers for a number of villages around the island, and the majority of inhabitants on the island live in these centers. 66 67 tween sides as described by kieser (1984). inbreeding analysis compared the children based on three rates of grandparental endogamy (i.e., grandparents born in the same settlement). one, an outbred group (some grandparents were not from the island). two, a group with “low inbreeding” (one or two grandparents born in the same village). three, a group with “high inbreeding” (all four grandparents born in the same village). this was done across all studied villages. several previous studies in hvar showed that complete grandparental endogamy is a reliable indicator of inbreeding in these small villages, as most (if not all) individuals will eventually be related at some point in history (rudan and rudan, 2000; smolej-narančić and rudan, 2001). thus, complete endogamy in these populations in some instances carries greater potential to discriminate inbred from non-inbred individuals than the actual genealogical reconstruction, because the latter tends to underestimate the remote component of inbreeding (broman and weber, 1999; shifman and darvasi, 2001). the present study design was to evaluate the effect of inbreeding on carabelli’s trait at the individual level. the study has the benefit of reduced environmental variance across studied villages, a feature that has been documented previously (rudan et al., 1999). the statistical significance of the differences in frequencies was evaluated using a chi-square test, and symmetry was evaluated using the wilcoxon test with alpha level set at 0.10 and at 0.05. pearson chi-square value, likelihood ratio and linear-by-linear association inbreeding and carabelli’s trait grade of carabelli’s trait 0 1 2 3 4 5 6 7 total outbred number 5 1 6 0 0 2 0 0 14 percent 35.7 7.1 42.9 0.0 0.0 14.3 0.0 0.0 low inbreeding number 19 14 17 9 34 23 9 1 126 percent 15.1 11.1 13.5 7.1 27.0 18.3 7.1 0.8 high inbreeding number 4 5 12 3 14 16 5 2 61 percent 6.6 8.2 19.7 4.9 23.0 26.2 8.2 3.3 total number 28 20 35 12 48 41 14 3 201 prcent 13.9 10.0 17.4 6.0 23.9 20.4 7.0 1.5 table 3. distribution of left carabelli trait according to dahlberg’s classification grade of carabelli’s trait 0 1 2 3 4 5 6 7 total outbred number 5 1 5 1 0 2 0 0 14 percent 35.7 7.1 35.7 7.1 0.0 14.3 0.0 0.0 low inbreeding number 19 14 13 16 34 17 10 1 124 percent 15.3 11.3 10.5 12.9 27.4 13.7 8.1 0.8 high inbreeding number 7 4 10 4 12 14 7 1 59 percent 11.9 6.8 16.9 6.8 20.3 23.7 11.9 1.7 total number 31 19 28 21 46 33 17 2 197 prcent 15.7 9.6 14.2 10.7 23.4 16.8 8.6 1.0 table 4. distribution of right carabelli trait according to dahlberg’s classification 68 69 statistic value df p chi-square 21.988* 14 0.079 likelihood ratio 24.312 14 0.042 mantel-haentzel 7.138 1 0.008 were presented after testing inter-group differences. likelihood ratio is a goodness-of-fit statistic similar to pearson’s chi-square and equivalent to it in large sample sizes—with the advantage that it can be subdivided into interpretable parts that add up to the total. linear-bylinear association (i.e., the mantel-haenszel chi-square test) is a measure of linear association between the row and column variables. results trait expression tables 3 and 4 show the distributions of carabelli’s trait on the left and right first molars in the outbred sample, and the samples with low and high inbreeding. all distributions varied significantly in frequency between groups (p < 0.05) for each side of the arch (tables 5 and 6). in the outbred group, grade 0 on the right side and 0 and 2 on the left side occurred most frequently. in the sample with inbreeding, grade 4 (group with low inbreeding) and 5 (group with high inbreeding) were most common. chi-square tests (tables 5 and 6) disclosed statistically significant differences among the groups (p < 0.05 for left side and 0.10 > p > 0.05 for right side) with different degrees of inbreeding when carabelli’s trait was divided into absent, negative, and positive expressions. positive trait expression was observed in 14% of the individuals in the outbred group, 23-26% with low inbreeding, and 37-38% with high inbreeding. absence of the trait was observed in 36% of the outbred individuals but only 7-12% of individuals with high inbreeding. trait symmetry the distribution of the grades in 197 individuals is shown in table 7. significant correlation (p < 0.001) was observed between the sides of the jaw (table 8). no individual showed a positive cusp on one side and absence of the character on the other. however, twelve individuals (5%) showed a negative expression unilaterally, with no trait on the other side. table 9 shows the distribution of carabelli’s trait according to dahlberg’s classification, and table 10 shows the left-right concordance according to the negative and positive expressions among the individuals with different inbreeding levels. no significant difference was found among the groups (table 11). using dahlberg’s classification, inbred individuals were more symmetric than those from the outbred group. the opposite finding was observed when comparing a negative and a positive expression, namely more asymmetric expressions occurred in inbred groups. discussion the highly endogamous population of hvar is characterized by a very high frequency of carabelli’s trait. the overall frequency was 84% on the right side and 86% on the left side. this is approximately the same as the highest frequency of the trait reported by kirveskari (1974) among skolt lapps (90%). a positive cusp was observed in 29% of individuals on the left side and 26% on the right side, which is somewhat higher than the value observed among skolt lapps (20%) and is almost equal to findings by townsend and martin (1992) in a sample of caucasian twins and to the frequency in the german population (30%) reported by reiners-karsch (1964). a higher frequency of the cusp has only been reported by keene (1968) among north-american military recruits (38%). the literature illustrates that inbreeding can affect orofacial traits. direct evidence for the influence of inbreeding on orofacial traits and on syndromes has, for example, been provided by schull and neel (1965), maatouk et al. (1995), and zlotoroga (1997) on humans and by baume and lapin (1983) on papio hamadryas. indirect evidence for the effect of inbreeding on orofacial traits in humans can be found in studies reporting higher prevalence of various orofacial traits in small isolated consanguineous communities such as yanomami indians of brazil (pereira and evans, 1975), the kwaio of the solomon islands (lombardi and bailit, 1972), and ashkenazi jews (ben-bassat et al., 1997). however, the carabelli trait has not previously been the focus of inbreeding investigations. the biologically isolated population of hvar island was divided into three groups in this study. first, there was a group with some grandparents who moved to the island from abroad, carrying new genes into the island’s gene pool (the outbred group). this group consists of just 14 children, but this represents the actual proportion of incomers. the second and the third groups are individuals whose ancestors were born on the island. in the second group are individuals with up to two grandparents from the same village, whose inbreeding scores range from 0.0039 to 0.0156. the third group consists of individuals with three or four grandparents from the table 6. statistical tests for data from the right side *10 cells (41.7%) have expected counts less than 5. the minimum expected count is 0.14. t. lauc statistic value df p chi-square 23.944* 14 0.047 likelihood ratio 26.689 14 0.021 mantel-haentzel 9.662 1 0.002 table 5. statistical tests for data from the left side *12 cells (50.0%) have expected counts less than 5. the minimum expected count is 0.21. 68 69 same village, mostly villages with an inbreeding score over 0.0156, which is representative of an extremely isolated group. using dahlberg’s classification, absence of carabelli’s trait was the modal finding in the outbred group, while grade 4 was most common in the low-inbreeding group, and grade 5 was most common in the high-inbreeding group. of note, there was an obvious and statistically significant dose-response relationship for the expression of carabelli’s cusp (dahlberg’s grade 5, 6 and 7) with the degree of inbreeding. this association between inbreeding and trait frequency implies that the trait may be modulated by recessive genes. rudan (2002) has noted that an increase in inbreeding of 5% corresponds to having about 1750 random genes across the genome identical by descent if the total number of human genes is between 30,000 and 40,000 (subramanian et al., 2001). if this unrecombined homozygosity has a notable effect on carabelli’s trait frequency, two mechanisms could explain it, (1) homozygosity brings together rare major genes or (2) the genes controlling this trait are of small effect but are incredibly numerous, scattered across the genome. genes with major effects arise after mutations that are considered to be extremely rare, because the probability of a random mutation that causes a small effect is much greater. even if such mutations are present in some individuals, it is extremely unlikely that similar effects of inbreeding, as the high significance of linear-by-linear association indicated, would be observed in the whole group with high inbreeding and across all of the villages. it is more likely that the carabelli trait is therefore a polygenetic trait. moreover, as results from this study indicate, it seems that the trait is caused by a rare allelic variant rather then a common one because if the trait were caused by common allelic variants, inbreeding could not increase the frequency in the homozygotes. a large number of genes involved in the model of trait expression can be explained as a product of a dynamic developmental program manifested in the activation of the developmental modules. as jernvall and jung (2000) suggest, a cascade model of molar trait development includes a number of stages and can be used to explain the variation of properties of dental characters and character states related to cusp initiation. a portion of a number of genes involved in such a complex developmental model can be recognized in different and tissue-related homeobox gene expression (transcription factors responsible for activation of primary genes and direct the differentiation of whole body parts (gilbert et al., 1996)). despite our expectation of significant difference of bilateral symmetry among the groups, all groups had similar distributions of bilateral asymmetry. increased fluctuating asymmetry in the inbred group had been left-hand side right hand side absent negative positive total absent negative positive total outbred number 5 7 2 14 5 7 2 14 percent 35.7 50.0 14.3 35.7 50.0 14.3 low inbreeding number 19 74 33 126 19 77 28 124 percent 15.1 58.7 26.2 15.3 62.1 22.6 high inbreeding number 4 34 23 61 7 30 22 59 percent 6.6 55.7 37.7 11.9 50.8 37.3 total number 28 115 58 201 31 114 52 197 percent 13.9 57.2 28.9 15.7 57.9 26.4 table 7. distribution of carabelli trait according to negative-positive dichotomy statistic value df p right side chi-square 10.466a 4 0.033 likelihood ratio 9.701 4 0.046 mantel-haentzel 8.606 1 0.003 left side chi-square 9.275b 4 0.055 likelihood ratio 8.288 4 0.082 mantel-haentzel 6.745 1 0.009 table 8. statistical tests for data from the sides after dichotomizing the data into negative and positive trait expressions a2 cells (22.2%) have expected counts less than 5. the minimum expected count is 1.95. b2 cells (22.2%) have expected counts less than 5. the minimum expected count is 2.20. inbreeding and carabelli’s trait 70 71 anticipated because individuals with reduced genetic heterogeneity are more sensitive to environmental stress during ontogeny (e.g., bailit et al., 1970; thornhill and moller, 1997). results of left-right concordance when using dahlberg’s eight grades differ from those that lump the expressions into a positive-negative dichotomy. dahlberg’s classification is more precise and only virtually-identical expressions are recognized as bilaterally symmetric, whereas different grades of positive and negative expressions will be pooled together in the second, dichotomous classification. however, a similar symmetry distribution was observed with both classifications, rejecting the hypothesis about influence of inbreeding on fluctuating asymmetry of carabelli’s trait. if inbreeding increases the symmetry of a trait, one explanation is that different genes with recessive variants are responsible for trait expression on the left and right sides of the arcade. this explanation can be rejected here because the repeated activation of the developmental modules during tooth development suggests that homologous cusps and crests are not coded as such into the genome, but that the whole cusp pattern is a product of a dynamic program (jernvall, 2000; zhao et al., 2000). obviously, high bilateral symmetry of the trait in various investigations implies that a multitude of other environmental factors during the development of the trait have no significant effect. it seems that this trait is almost completely genetically determined with a predominant genetic variance and that most of factors during odontogenesis are not environmental. those factors, as jernvall and jung (2000) commented on for primate molar shapes, “do not reflect just a static genetic code readable deep inside the genome, but rather, it is a readout of the information stored in the dynamic cuspmaking program.” therefore, polygenic developmental module responsible for the diversity of carabelli trait could be variable, but it stays relatively stable after initiation of the developmental process. acknowledgements this work was supported by the croatian ministry of science and technology grant no. 0196001 to nina smolej naranèiæ and “international research development award” from the wellcome trust to igor rudan and harry campbell. the author wishes to acknowledge irena martinović klarić. a special acknowledgement goes to professor nina smolej narančić and professor pavao rudan for their scientific guidance. literature cited alvesalo l, nuntila m, portin p. 1975. the cusp of carabelli. acta odontol scand 33:191-197. bailit hl, workman pl, niswander jd, maclean jc. 1970. dental asymmetry as an indicator of genetic and environmental conditions in human populations. hum biol 42:626-638. right-hand side class 0 1 2 3 4 5 6 7 total 0 23 1 3 32 1 4 9 1 5 18 2 3 4 20 3 2 1 26 3 3 8 1 19 4 1 1 1 2 35 4 1 45 5 1 3 7 23 6 34 6 1 4 8 1 17 7 1 1 2 total 28 19 33 12 45 40 14 2 193 l ef t si d e table 9. occurrence of carabelli trait on the maxillary first molar on the two sides of the dental arcade* *kendall’s tau = -0.735. dahlberg’s eight-grade scale dichotomized trait expressions group symmetric asymmetric total symmetric asymmetic total outbred number 3 11 14 12 1 13 percent 21.4 78.6 92.3 7.7 low inbreeding number 42 78 420 100 17 117 percent 35.0 65.0 85.5 14.5 high inbreeding number 20 37 57 46 7 53 percent 35.1 64.9 86.8 13.2 total number 65 126 191 158 25 183 percent 34.0 66.0 86.3 13.7 table 10. left-right symmetry of trait expression t. lauc 70 71 baume rm, lapin ba. 1983. inbreeding effects on dental morphometrics in papio hamadryas. am j phys anthropol 62:129-135. ben-bassat y, harari d, brin i. 1997. occlusal traits in a group of school children in an isolated society in jerusalem. br j orthod 24:229-235. biggerstaff rh. 1973. heritability of the carabelli cusp in twins. j dent res 52:40-44. bodmer wf, cavalli-sforza ll. 1976. genetics, evolution, and man. san francisco: wh freeman and company. broman kw, weber jl. 1999. long homozygous chromosomal segments in reference families from the centre d’etude du polymorphisme humain. am j hum genet 65:1493-1500. dietz vh. 1944. a common dental morphotropic factor, the carabelli cusp. j am dent assoc 31:784-789. gilbert sf, opitz jm, raff ra. 1996. resynthesizing evolutionary and developmental biology. dev biol 173:357-372. goose dh, lee 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estimation of inbreeding, kinship, genetic distances, and population structure from surnames: the island of hvar, croatia. am j hum biol 9:595-607. rudan p. etude sur les dermatoglyphes digito-palmaires des habitants de l’ile de hvar. 1972. paris: univerzitate paris (ph.d. dissertation). rudan i, campbell h, rudan p. 1999. genetic epidemiological studies of eastern adriatic islands isolates, croatia: objectives and strategies. coll antropol 23: 531-546. rudan p, finka b, janićijević b, jovanović v, kušec v, miličić j, mišigoj-duraković m, roberts df, schmutzer lj, smolej-narančić n, sujoldžić a, szirovicza l, šimić d, šimunović p, špoljar-vržina sm. 1990. anthropological investigations of eastern adriatic. vol 2. biological and cultural microdifferentiation of the rural populations on the island of hvar. zagreb: croatian anthropological society. rudan p, roberts df, janićijević b, smolej n, szirovicza l, kastelan a. 1986. anthropometry and the biological structure of the hvar population. am j phys anthropol 70:231-240. rudan p, roberts df, sujoldžić a, macarol b, smolej n, kaštelan a. 1982a. strategy of anthropological research on the island of hvar. coll antropol 6:39-46. rudan p, roberts df, sujoldžić a, macarol b, smolej n, kaštelan a. 1982b. geography, ethnohistory and demography of the island of hvar. coll antropol 6: 47-68. rudan i, rudan p. 2000. comparison between coef statistic value df p eight-grade scale chi-square 1.069a 2 0.586 likelihood ratio 1.149 2 0.563 mantel-haentzel 0.405 1 0.525 dichotomized expression chi-square 0.477b 2 0.788 likelihood ratio 0.539 2 0.764 mantel-haentzel 0.042 1 0.837 table 11. statistical tests for left-right symmetry of trait expression a1 cell (16.7%) has expected counts less than 5. the minimum expected count is 4.76. b1 cell (16.7%) has expected counts less than 5. the minimum expected count is 1.78. inbreeding and carabelli’s trait 72 73 ficients of inbreeding computed from deficit of heterozygotes for codominant autosomal genetic polymorphisms and from isonymy data: a study of hvar island isolates, croatia. in: susanne c, bodszar eb, editors. human population genetics in europe. budapest: biennial book of european anthropological association vol. 1, p 117-128. rudan i, rudan d, campbell h, biloglav z, urek r, padovan m, sibbett l, janićijević b, smolej narančić n, rudan p. 2002. inbreeding and learning disability in croatian island isolates. coll anthropol 26:421-428. schull w, neel j. the effect of inbreeding on japanese children. 1965. new york: harper and row. scott gr, potter rhy. 1984. an analysis of tooth crown morphology in american white twins. anthropol 22:223-231. shifman s, darvasi a. 2001. the value of isolated populations. nat genet 28:309-310. šimić d, chaventré a, plato cc, tobin jd, rudan p. 1992. factor structure of morphometric variables measured on six metacarpal bones. ann physiol anthropol 11:3-12. šimić d, rudan p. 1990. isolation by distance and correlation 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gc, brown t. 1981. the carabelli trait in australian aboriginal dentition. arch oral biol 26: 809-814. townsend gc, martin ng. 1992. fitting genetic model to carabelli trait data in south australian twins. j dent res 71:403-409. waddle dm, sokal rr, rudan p. 1998. factors affecting population variation in eastern adriatic isolates (croatia). hum biol 70:845-864. zhao z, weiss km, stock dw. 2000. development and evolution of dentition patterns and their geneic basis. in: teaford m, smith mm, ferguson m, editors. development, function and evolution of teeth. cambridge: cambridge university press, p 152-172. zlotogora j. 1997. genetic disorders among palestinian arabs: 1. effects of consanguinity. am j med genet 68:472-475. t. lauc ebba during reports that thearchaeoosteological research laboratory, royal castle ulriksdal, s-17079 solna, sweden, has undergone a name change to a “less lumbering” title. the new name is osteoarchaeological research laboratory. the address remains the same. professor during is head of the laboratory, and she can be reached via e-mail at: ebba.during@ofl.su.se. laboratory name change corruccini et al. 2002.2 8 9 huaca loro (ca. a.d. 1000) is a monumental adobe platform mound with a series of deep shaft tombs under and around its base. this mound with a temple at the top is situated in the poma national historical sanctuary on the north coast of peru. the sicán archaeological project has conducted fieldwork in and around poma for more than 2 decades (shimada, 1981, 1990, 1995, 2000). since 1990, excavations have included recovery of 34 individuals from the east tomb, west tomb and north trench (shimada et al., 1998, 2000; shimada and merkel, 1993). comparative odontological (corruccini and shimada, 2002) and other analyses (shimada et al., 1998, 2001; farnum et al., 1998) pertain to these remains. corruccini (1998) cites other studies concurring that dental variables are informative for establishing genetic and familial affinities between samples. with the recent addition of mtdna analysis of the teeth (shimada et al., 2001), it is possible to examine the dental traits for overall (multivariate) and trait-specific (univariate) concordance with a known genetic variant. dental indications of biological relatedness were sought within and between the following nine partitions of the total sample: the principal west tomb burial at the center of the central chamber, a juvenile male “looking” at him from the antechamber higher up, two accompanying (possibly sacrificial) females in south and north niches of the central chamber, eight scorable females to the south, eight scorable females from the grouping to the north, five inferred “commoners” from the north trench, and the principal (adult male) interment and three other individuals (two adult females and a juvenile) from the east tomb. see figure 1. from silicon molds taken by r. benfer and i. shimada of maxillary and mandibular arches and dental stone casts made by w. duncan, 23 dental traits scored by r. corruccini yielded size-equalized euclidian distance coefficients between those 29 adequately preserved individuals. the traits were scored for the most part according to turner et al. (1991) and corruccini and potter (1981) on the best preserved side. considerably more descriptive detail is in the publication by corruccini and shimada (2002): 1. maxillary central incisor labial convexity. 2. maxillary incisor shoveling. 3. maxillary double shoveling. 4. mandibular incisor shoveling. 5. canine accessory ridge and basal tubercle. 6. maxillary distal premolar buccal cusp (paracone) diameter. 7. mandibular distal premolar lingual component mesiodistal diameter. 8-9. hypocone development on maxillary m1 and m2. 10. maxillary m3 metacone. 11-13. cusp number for mandibular m1-3. 14-15. chord from mesial fovea to central fovea for mandibular m1-2. 16-17. chord from central fovea to distal fovea (or distal marginal ridge) for mandibular m1-2. 18-19. chord from central to distal fovea on maxillary m1-2. 20. m 1 bilaterally lost in the presence of m2 (not an appeal to congenital but rather pathological genetic tendencies). 21. m 2 bilaterally lost in the presence of m1. 22. central incisor winging. 23. third cusp (“entoconid”) lingual development on the distal mandibular premolar. random resampling of the resultant distances yielded p = 0.006 for the null hypothesis of random odontological intracemetery patterning. among salient aspects of the statistically significant result (corruccini and shimada, 2002) were three particular patterns: the dental and mtdna relatedness among thousand-yearold remains from huaca loro, peru robert s. corruccini1, izumi shimada1, and ken-ichi shinoda2 1department of anthropology, southern illinois university, carbondale, il 62901-4502 usa 2department of anatomy and physiology, saga medical school, saga, japan correspondence to: r. s. corruccini, anthropology department, southern illinois university, carbondale, il 62901-4502. e-mail: rcorrucc@siu.edu abstract within and between tombs at the site of huaca loro (ca. a.d. 1000) on north coastal peru, biological relatedness based on 23 dental characters follows statistically significant patterns. mtdna groupings that are based on lineages inferred from inherited derived d-loop bp sequences have also been traced among the individuals. the present study finds a significant, although rather poorly predictive, relation between mtdna and dental interindividual linkages. when analyzing the individual dental traits for correspondence to mtdna “lineages”, several significant relations are found and one trait in particular, buccal expansion of the maxillary distal premolar, corresponds highly to mtdna patterning. 10 11 morphological cohesiveness of the south females, the heterogeneity among north females, and high similarity among the inferred high-status males of east and west tombs. teeth are useful for ancient mtdna analysis, and an unrelated earlier study was successful in correlating biokinship measured from both mtdna and odontometry (shinoda et al., 1998). a well-preserved tooth was extracted by ks from each individual. whole teeth were soaked in dna contaminant removal solution, rinsed in distilled water and dried. mtdna was extracted from ground tooth powder (shimada et al., 2001) following a modified protocol (genrclean kit; bio 101 co.). eluted dna was amplified by pcr. results several probably derived mtdna sequences are identifiable among the interments. most new world indigenous mtdna polymorphisms are at the mitochondrial “d-loop” (gonzalez-oliver et al., 2001). a combination of rflp haplotype and d-loop sequence analysis determined variants successfully for 18 west tomb, 3 east tomb and 2 north trench individuals. sequences encompassing 192 bp were determined in which mutations were found at 25 sites. at 24 sites transition mutations alone occurred, c to t transition observed 16 times and a to g 8 times. in studies involving dna of ancient samples the original sequences may easily have changed. this potential limitation (implying differential degradation particularly involving a/g versus c/t transitions) may apply also to the celebrated neandertal studies (krings et al., 1997). among the individuals included in the dental analysis, the pertinent “lineages” implying shared maternal ancestry (of uncertain remoteness) are indicated in table 1 and figure 1. these include haplotypes uniting the north niche female and 3 other of the north females, and two distinct haplotypes occurring in 5 of the south females. thus various women within but not between north and south groupings are related. in addition the east and west tomb male principal interments (plus one other, north trench burial) are more tenuously linked. although the initial finding of relatedness between east and west tomb principal individuals could not be replicated a second time owing to problems with extracting and reproducing the west individual’s dna, there was no negation of a genetic link between these two. in comparing the dental distances within these genetically inferred matrilineages versus distance between them, an overall mean of 1.40 is found within the 13 interindividual d’s (3+6+3+1) that are intralineage, and d=1.41 for all the remaining interlineage pairs admittedly not arguing for much difference. however, the time depth of the postulated shared maternal ancestry remains unknown, and could vary according to the different haplotypes, whereas the dental variants would be inherited through nuclear dna recombined from both parents with a generational diluting effect on the matrilineage from ongoing male input. furthermore, the north females have an undue influence on results, constituting 46.2% of the intralineage d’s in table 1 (6/13) but only accounting for 7.6% of interlineage d’s. since these north females have consistently very large dental d’s, they disproportionately inflate the intralineage distance. accordingly a matched comparison can be designed as indicated in table 1, contrasting the dental affinities of the 13 dna-linked pairs with their spatially closest corresponding groups that are unlinked. those individuals linked by mtdna pattern are quite consistently (but very slightly) closer in dental pattern than the “unrelated” individuals (paired t = 3.12, 12 d.f., one-tailed p < 0.005). the p remains < 0.01 (11 df) when the one pair of distances involving east and west tomb principal individuals, the most tenuous mtdna linkage, is removed. table 1. average linear euclidian distances over 23 dental traits (converted to normalized shape variables) among individuals belonging to distinct mtdna types compared to distances among the remainder of their archaeologically positioned group1 lineage d within compared to d within first* (3) 1.284 other east tomb, north trench occupants 1.482 second**(3) 1.566 north niche to unrelated north females 1.694 second**(3) 1.552 all other north females 1.573 third***(3) 1.268 other south females 1.250 fourth****(1) 1.219 other south females 1.250 1the number in parentheses is the number of comparisons within a mtdna “lineage” that can be contrasted with matching average d within the appropriate comparison group. *east tomb principal interment, west tomb principal, and burial 3 from north trench **north niche (sacrificial) central chamber female d to the other 3 north females of same mtdna type, compared to her d from unrelated north females. then the d within the seemingly related 3 north females is compared to the d among all other north females ***south female burials 10, 13 and 14 ****south female burials 6 and 8 dental and mtdna relatedness 10 11 having detected an admittedly subtle yet significant parallel between dental discordance and mtdna unrelatedness, it is of interest to see which traits correspond most closely within these “matrilineages”. this is attempted in table 2, where the pairwise squared interindividual variance is contrasted within the linked groups and between remaining unlinked individuals. the f-ratio can be used to test the onetailed proposition that variances shall be smaller among pairs of individuals within mtdna types, but some consideration of the degrees of freedom is warranted. only 29 total individuals have yielded (29 x 28)/2 = 406 pairwise differences. the f statistic will be subject to type i error when read with an inflated 392 and 12 degrees of freedom (406-13-1 d’s between and 13-1 d’s within haplotypes). at the other extreme, reducing this to a minimalist 16 (17 unlinked individuals minus 1) and 11 (12 individuals involved in mtdna matches minus 1) degrees of freedom will substantially overcorrect and bring about type ii error. furthermore, there is concern over the redundancy effect of testing multiple (23) separate null hypotheses using the same sample of individuals repeatedly. this is the bonferroni effect (sokal and rohlf, 1987:17-18) and can be corrected (probably too harshly, as there would only be partial redundancy) by adjusting the critical probability from the usual p = 0.05 to 0.05/23 = 0.0022. table 2 shows the two extremes, i.e., maximized d.f. that will be very sensitive, and minimized d.f. with bonferroni’s correction included. the latter sets rather high standards for a significant result. the reality about the null probability is presumably somewhere between those estimates. six of the 23 traits indicate significant partition of variance according to mtdna homogeneity, quite a bit more than the random expectation of 23 x 0.05 = 1.15 results expected to be due to type i error when the critical p is 0.05. thus there does seem to be familial resemblance affecting the teeth, although this might be thought unlikely to be detectable unless the shared maternal ancestry is fairly recent or the trait is sex-linked. looked at another way, the directional f-ratios have a geometric mean well over 1.0, again suggesting overall segregation of dental variance according to mtdna affinity. that one of the traits, the distal maxillary premolar paracone inflation, clears the bonferroni hurdle suggests not only that this particular variable is confidently rejecting the null hypothesis, fig. 1. spatial distribution of individuals with matching haplotypes within the west tomb indicated by outlined symbols (i.e., circle, triangle, square, and diamond). the solid black circles represent individuals who are not maternally related to anyone else within the tomb. only one of the three females represented by diamonds preserved adequate teeth, so there is no intra-group contribution from that haplotype. dental and mtdna relatedness 12 13 but clears the way for the conclusion of a significant “treatment effect” among the variables in general. in addition to the strongly significant paracone diameter, two other of the traits indicating significant similarity among relatives (according to the broader interpretation of d.f.) are metric, the second mandibular molar’s mesial occlusal diameter (trait 15) and the mandibular distal premolar’s lingual mesiodistal diameter; the latter (trait 7) measures somewhat the same thing as p4 third cusp presence (trait 23) which is also significant. the other non-mensurational traits with significant f in table 2 are mandibular incisor shoveling and incisor winging. discussion molar traits figure less than premolar traits in the list of significant results in table 2, but this may signify little for genetic interpretations of odontological variants. correspondence to mtdna affinity may be haphazard for dental traits, although of some interest in analyses of prehistoric samples in regard to the matrilocal/ patrilocal question (corruccini, 1998). comparison to nichol (1989:table 4) yields perspective from a vaguely related (amerind: pima) sample, for which segregation analysis of individual dental variables estimates the heritable tendencies among families. nichol does not detect unusually strong genetic segregation for winging or shoveling, although both probably have significant transmissibility (the former fitting a polygenic and the latter a dominant or major gene model best). the distal mandibular premolar lingual extra cusp may fit a dominant or polygenic model with higher transmissibility than winging and shoveling, but not higher than other traits. the possibility of sex-linked heritability is particularly interesting here due to maternal mode of transmission of mtdna. however nichol does not examine sex-linked tendencies. other studies send mixed signals (garn et al., 1965; townsend and brown, 1978) regarding sex-linkage of overall tooth size. one crown variant, carabelli’s cusp, has been examined thoroughly and does not appear sex-linked in its heritability (townsend and martin, 1992; garn et al., 1966). some confidence is gained here for the widely accepted procedure of treating dental variables as genetic indicators. speculation regarding specific family affinity of individuals, and sex-linked inheritance of variables that correspond to mtdna “lineages”, is just that. one outstanding biological dilemma is provided by the relatively widespread mtdna connection among north females who are relatively dentally disparate. table 2. mtdna “lineage” segregation (variance among non-lineage individual pairs divided by variance within mtdna lineage pairs) over the 23 dental traits for 29 individuals trait number among within f-ratio 1 0.349 0.174 2.09 2 0.954 0.634 1.51 3 0.752 1.406 0.53 4 0.848 0.350 2.42* 5 0.585 0.814 0.72 6 72.022 8.094 8.90** 7 54.925 16.000 3.43* 8 2.303 4.111 0.56 9 21.258 14.778 1.44 10 0.188 0.136 1.38 11 1.559 4.400 0.35 12 11.824 26.818 0.44 13 35.154 48.714 0.72 14 17.962 26.400 0.68 15 23.747 19.900 1.19 16 27.527 8.050 3.42* 17 29.201 16.500 1.77 18 16.109 28.889 0.56 19 36.314 48.875 0.74 20 0.118 0.231 0.51 21 0.221 0.154 1.43 22 0.168 0.038 4.37* 23 0.355 0.066 5.36* *broadly significant, f for 392 and 12 d.f. yields p < 0.05 **narrowly significant, f for 16 and 11 d.f. yields p < 0.05/23 = 0.0022 dental and mtdna relatedness 12 13 models incorporating incremental generational change in polygenic dental variables, contrasting with the unadmixed maternal mtdna transmission, could be contemplated. perhaps the south females, dentally similar, are closely related by way of males such as would come about through, say, a sororal polygynous background, while the north females (who are also distinct in terms of archaeological indicators) might be distantly related through female ancestors such as could result from matrilocal background. thus familial resemblance affecting the highly heritable dental traits reverberates somewhat through the mtdna linkages, but, as is quite expectable, the correspondence is imperfect and susceptible to speculations about matrilocal versus patrilocal biological transmission. acknowledgments excavations at huaca loro and laboratory analyses from 1990 to 1997 by the sicán archaeological project were supported by two grants generously provided to i.s. by the shibusawa ethnological foundation, tokyo. the mtdna analysis by k.s. was supported by a grant-in-aid for scientific research from the ministry of education, science, sports and culture, japan. i.s. is grateful for tireless efforts of c. elera, r. vega-centeno, j. montenegro, l. le ber and v. curay in the excavations of the east and west tombs and the north trench at huaca loro. r. benfer and w. duncan made the silicon molds and plaster casts. references cited corruccini rs. 1998. on cemetery kin groupings at hawikku. am antiq 63:161-163. corruccini rs, potter rhy. 1981. developmental correlates of crown component asymmetry and occlusal discrepancy. am j phys anthropol 55:2131. corruccini rs, shimada i. 2002. dental relatedness corresponding to mortuary patterning at huaca loro, peru. am j phys anthropol 117:113-121. farnum j, corruccini r, mine k, shimada i, vegacenteno r, curay v. 1998. sicán funerary customs: an interdisciplinary perspective. paper presented at the 26th annual midwest conference on andean and amazonian archaeology, anthropology and ethnohistory, university of illinois at urbanachampaign. garn sm, lewis ab, kerewsky rs. 1965. x-linked inheritance of tooth size. j dent res 44:439-441. garn sm, lewis ab, kerewsky rs, dahlberg aa. 1966. genetic independence of carabelli’s trait from tooth size or crown morphology. arch oral biol 11:745747. gonzalez-oliver a, marquez-morfin l, jimenez jc, torre-blanco a. 2001. founding amerindian mitochondrial dna lineages in ancient maya from xcaret, quintana roo. am j phys anthropol 116: 230-235. krings m, stone a, schmitz rw, krainitzki h, stoneking m, paabo s. 1997. neandertal dna sequences and the origin of modern humans. cell 90:19-30. nichol cr. 1989. complex segregation analysis of dental morphological variants. am j phys anthropol 78:37-59. scott gr, turner cg. 1997. the anthropology of modern human teeth. cambridge: cambridge university press. shimada i. 1981. the batán grande la leche archaeological project: the first two seasons. j field archaeol 8:405-446. shimada i. 1990. cultural continuities and discontinuities on the northern north coast, middlelate horizons. in: moseley me, cordy-collins a, editors. the northern dynasties: kingship and statecraft in chimor. washington dc: dumbarton oaks, p 297-392. shimada i. 1995. cultura sicán: dios, riqueza y poder en la costa norte del perú. lima: banco continental. shimada i. 2000. late prehispanic coastal states. in: minelli ll, editor. pre-inka states and the inka world. norman: university of oklahoma. p. 49-110. shimada i, corruccini r, farnum j, mine k, vegacenteno r, curay v. 1998. sicán population and mortuary practice: a multi-dimensional perspective. paper presented at the 63rd annual meeting of the society for american archaeology, seattle. shimada i, gordus a, griffin ja. 2000. technology, iconography, and significance of metals: a multidimensional analysis of middle sicán objects. in: mcewan c, editor. pre-columbian gold: technology, iconography, and style. london: british museum press. p 28-61. shimada i, merkel j. 1993. a sicán tomb in peru. minerva 4:18-25. shimada i, shinoda k, corruccini r, farnum j. 2001. biological and social dimensions of sicán burials: integrating artifact, dna, dental, and dietary analyses. paper presented at the 66th annual meeting of the society for american archaeology, new orleans. shinoda k, matsumura h, nishimoto t. 1998. genetical and morphological analysis on kinship of the nakazuma jomon people using mitochondrial dna and tooth crown measurement. zooarchaeology 11: 1-21. sokal rr, rohlf fj. 1987. introduction to biostatistics, 2nd ed. new york: wh freeman. townsend gc, brown t. 1978. inheritance of tooth size in australian aboriginals. am j phys anthropol 48: 305-314. townsend gc, martin ng. 1992. fitting genetic models to carabelli trait data in south australian twins. j dental and mtdna relatedness 14 15 dent res 71:403-409. turner cg, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, inc. p 13-31. dental and mtdna relatedness the albert a. dahlberg prize is awarded annually to the best student paper submitted to the dental anthropology association (daa). full details were printed in the last issue of this journal. papers may be on any subject related to dental anthropology. the recipient of the albert a. dahlberg student prize will receive a cash award of $200.00, a one-year membership in the dental anthropology association, and an invitation to publish the paper in dental anthropology. students should submit 3copies of their papers in english to the president of the daa. manuscripts must be received by january 31, 2003. the format must follow that of dental anthropology, which is similar to the style of the american journal of physical anthropology printed in 2002, volume 117(1). the guide to authors also is available at the web site for the ajpa (http://www.physanth.org). the manuscript should be accompanied by a letter from the student’s supervisor indicating that the individual is the primary author of the research and the paper. multiple authorship is acceptable, but the majority of the research and writing must be the obvious work of the student applying for the prize. send enquiries and submissions to the president of the daa: dr. joel d. irish department of anthropology university of alaska fairbanks, ak 99775-7720 u.s.a. the albert a. dahlberg prize p l e a s e a d v e r t i s e t h i s c o m p e t i t i o n t o y o u r s t u d e n t s tasa 2000.5 pg26.jpg gurri and balam 2006.4 29 double teeth have been described in the literature as the result of two developmental events taking place during the bud stage of tooth formation. these events are called gemination and fusion. the term gemination is described as an attempt at formation of two teeth from a single tooth bud, and fusion is the joining together of two teeth (shafer et al., 1974; pindborg, 1970; grahnen and granath, 1961). this being the case, gemination can more accurately be described as the result of an incomplete bifurcation of a single tooth bud at the early stages of development. fusion, on the other hand may result from the union of the epithelial cells of two different tooth buds, which will later develop into a single mesiodistally enlarged tooth. both fused and geminated teeth may share an enlarged pulp chamber and a single root canal, or may have separate root canals or bifurcated pulp chambers (maibaum, 1990; o’reilly, 1990; hosomit et al., 1989; reeh and el deeb, 1989; levitas, 1965). as a consequence, the identification of double teeth as geminated or fused teeth based on their shape is difficult, even when using radiographs. furthermore, some authors have argued that since both fusion and gemination are developmental processes that cannot be observed and that, to avoid confusion, they should not be separated for analysis (killian and croll, 1990; mader, 1979; brook and winter, 1970). in fact, the only practical way to classify them is by counting the double tooth as a single one. if the dental arch contains a normal set of teeth, the double formation is classified as gemination. on the other hand, if a tooth correspondence to: francisco d. gurri, el colegio de la frontera sur-unidad campeche, calle 10 no. 264, colonia centro, campeche, campeche, mexico, 24000, e-mail: fgurri@camp.ecosur.mx inheritance of bilateral fusion of the lower central and lateral incisors: a pedigree of a maya family from yucatan, mexico. francisco d. gurri1* and gilberto balam2 1departmento de población y ambiente, el colegio de la frontera sur-unidad campeche, and 2cinvestav-unidata merida, cordemex, merida yucatan, mexico abstract: a pedigree with five individuals exhibiting bilateral fusion of lower central and lateral incisors is described. it is the first pedigree ever published presenting this condition, and the individuals affected are the 6th through 10th cases in the literature. bilateral fusion of the lower central incisors may be the consequence of an autosomal dominant gene in this family. crown height and mesiodistal measurements on the permanent dentition of the affected individuals were compared to the same measurements taken on unaffected persons in their population. buccolingual and mesiodistal measurements on the deciduous dentition were compared to published means for populations around the world. fusion was associated with a genetic tendency towards tooth reduction, affecting tooth number in the jaw, and overall size. it also was concluded, as suggested by previous investigators, that fusion and gemination are under separate genetic control. dental anthropology 2006;19(1):29-34. is missing, the event is classified as fusion (pindborg, 1970; levitas, 1965). this approach is far from perfect since the synchronous presence of gemination, fusion, supernumerary teeth, and congenitally missing teeth could lead to misclassifications. moody and montgomery (1934) suggested that the formation of double teeth is under genetic control. since then, data supporting their hypothesis have continued to mount in human and nonhuman cases. for instance, double teeth have been encountered in a strain of lakeland terriers (hitchin and morris, 1966) and in human twins (nik-hussein and salcedo, 1987; dixon and stewart, 1976; grahnen and granath, 1961). trait frequencies vary among populations, being most common among people of asian and amerindian origins (bedy and moody, 1992; barac and skrinjaric, 1991; skrinjaric and barac, 1991; ishida et al., 1990; salem, 1989; hagam, 1988; stevenson, 1983; brook and winter, 1970; pindborg, 1970; curzon and curzon, 1967; grahnen and granath, 1961; saito, 1959). there has been disagreement, however, as to the mode of transmission of double teeth. dixon and stewart (1976), based on moody and montgomery (1934), and hitchin and morris (1966) proposed that double teeth may involve y-linked or holandric transmission. saito �0 (1959) studied 7,589 infants and 2,740 older children from 141 families with at least 1 affected individual. he considered both fused and geminated teeth as double teeth, and concluded that the trait follows a simple mendelian segregation ratio, and “double teeth” is due to a dominant gene with 73.8% penetrance in the primary dentition, 62.3% penetrance in the permanent, and 90.2% for both. double teeth most commonly involve (1) the central and lateral incisors and (2) the lateral and the canine, and they are more common in the primary dentition (grahnen and granath, 1961; pindborg, 1970; ishida et al., 1990; duncan and helpin, 1987). they also are more common in the mandible than the maxilla (brook and winter, 1970). finally, they are just as likely to be found in males as in females (jarvinen et al., 1980). in an effort to predict tooth number in the permanent dentition from the primary dentition, gellin (1984) investigated two independent relationships. first he found that there were associations between oligodontia, microdontia, and fusion. he then confirmed associations between supernumerary teeth, macrodontia and gemination. in addition, he found that while in all cases the teeth involved are the incisors and the canines, fusion (along with oligodontia) occurs predominantly in the lower jaw. in contrast, gemination and supernumerary teeth are usually found in the maxilla arch. these tendencies had already been reported by pindborg (1970), and later studies have supported these results (barac and skrinjaric, 1991; skrinjaric and barac, 1991; ishida et al., 1990; hagam, 1988 ). duncan and helpin (1987) reviewed the cases on bilateral fusion and gemination published in the literature up to 1987. cases reported by bricker and martin (1987), maibaum (1990) and nik-hussein (1989) were added to these and are summarized in table 1. as may be observed, bilateral fusion and gemination follow the observed patterns as their unilateral counterparts. the most commonly affected teeth in both situations are the incisors and the canines. gemination, both in the primary and secondary dentition, is predominantly a feature of the maxillary dentition, while fusion is more common in the mandible, especially in the primary dentition. fusion in the lower jaw, as in the unilateral cases, is accompanied by what could be considered oligodontia, while gemination is often associated with a supernumerary tooth. these differences suggest that fusion and gemination result from independent events. fusion may be associated to a mandibular process of tooth reduction and gemination to a maxillary process of tooth enlargement and increment in number. this being the case, the two processes may be under different genetic control, and regarding them as one may have hindered previous attempts to estimate the mode of inheritance table 1. total cases of bilateral fusion or gemination reported in the literature condition location teeth gemination primary dentition 75% maxilla central and lateral incisors. gemination permanent dentition 100% maxilla central incisors. fusion primary dentition 92.3% mandible 61.53% lateral incisors and canines. 38.46% central and lateral incisors. fusion permanent dentition 57.14% mandible, 1 lateral incisors and canines. 42.85% maxilla 5 central incisors and supernumerary (maxilla). 4 central and lateral incisors. 2 lateral incisors and canines. fig. 1. pedigree of mandibular fusion of central and lateral incisors in a yucatecan maya family (symbols for affected individuals are filled in). f.d. gurri and g. balam �1inheritance of fused teeth of double teeth. the present paper presents the 6th through 10th cases of bilateral fusion of the lower central and lateral incisors as near as can be determined. they were all detected in a single family, which makes this the first published pedigree of bilateral fusion. it would seem to be useful to determine the mode of inheritance of this pedigree. materials and methods during 1992, in the town of zavala, located in the maya region, state of yucatan, mexico, a family was examined as part of a survey on the frequency of enamel hypoplasia (gurri and balam, 1992). upon inspection of the mother ’s dentition, it was noted that she exhibited bilateral fusion of the lower central and lateral incisors. her children and husband where then examined, and it was observed that 4 of her offspring also exhibited the trait (fig. 1). in a subsequent visit, hydrocolloid impressions and plaster casts were made of all affected individuals except for a 1.5 year old child with a very small dental arch. attempts were also made to locate all living relatives. the casts were analyzed in the dental laboratory in the department of anthropology of indiana university. discrimination between fusion and gemination was based on counting the anomaly as one tooth, and summing the total number of teeth in the dental arcade (pindborg, 1970; levitas, 1965). to test for the presence of microdontia, the crown height measurements of individuals ii2 and iii6 where compared to the local population. crown heights on the permanent upper central, lower central incisors and lower canines were taken in this population as part of the research on enamel hypoplasia. however, no measurements were taken on the deciduous dentition. the mesiodistal and buccolingual dimensions of the upper central incisors, and the upper and lower canines of individuals iii2 and iii3 were compared to measurements published by grine (1986) for different populations around the world. measurements in the maya population were taken in vivo with a plastic vernier caliper and recorded to the nearest millimeter. measurements on the subject family were obtained from plaster casts with the same instrument. results the pedigree in figure 1 shows the results. the trait appeared in the mother (ii2 fig. 2), the youngest daughter iii1, and 3 of the sons (iii2, iii3, iii6; figs. 3-5). in all, 4 out of 7 live children have bilateral fusion of the central and lateral incisors, 3 in the primary dentition (iii1, iii2, iii3) and 1 in the permanent (iii6). the last child had died, and it was impossible to determine his dental condition since the family was unaware of its table 2. crown height percentiles in mm. for yucatecan maya populations males ages 10 to 15 years old females ages 30 to 40 years old percentile percentile tooth n 5 25 50 75 95 c6 n 5 25 50 75 95 b6 li1 100 7 8 8 9 10 6 77 6 7 8 9 10 8 ri1 99 7 8 8 9 10 6 76 6 7 8 9 10 8 lc 90 6 7 7 8 9 6 92 6 7 8 8 10 7 rc 90 6 7 7 8 9 6 91 6.6 7 8 8 10 6 table 3. mesiodistal breadth percentiles in mm. for yucatecan maya populations males females percentile percentile tooth n 5 25 50 75 95 iii6 n 5 25 50 75 95 ii6 li1 195 7 8 8 9 9 8.6 185 7 7 8 8 9 7 ri1 191 7 8 8 9 9 8.2 183 7 7 8 8 9 7.25 li1 205 4 5 5 5 6 7 218 4 5 5 5 6 8 ri1 204 4 5 5 5 6 5.25 220 4 5 5 5 6 7 lc 187 5.4 6 7 7 8 6 208 5 6 6 7 7 5 rc 187 5 6 7 7 8 6 209 5 6 6 7 7 5.5 �2 existence. a brother (ii1) and a first cousin of the affected mother were found, neither of whom was found to have the condition. affinal relatives were also available for examination, but, as shown on the pedigree, neither her husband (ii3) nor anyone in his family (i1, ii4, ii5) was affected. table 2 shows a crown height percentile distribution for maya women, ages 30 to 40, and males, ages 10 to 15. the 4 crown heights for individual ii6, a female age 36, correspond to the 25th, 50th, 25th and 5th percentiles. all of the crown height measurements on individual iii6, a 12 year old boy, fell within the 5th percentile of his population. table 3 shows mesiodistal percentile distributions for males and females in the local maya population. mesiodistal measurements for the lower canines in iii6 correspond to the 25th percentile and in ii6 to the 5th. the central upper incisors in b6 correspond to the 5th and 25th percentiles, and the mesiodistal dimensions of c6 correspond to the 50th. tables 4 and 5 show the mesiodistal and buccolingual diameters of ui1, ui2, uc and lc for different populations, and for individuals iii2 and iii3. except for ui1, whose mesiodistal dimensions are smaller than the average of any of the reference populations, all other teeth appear normal. the buccolingual breadths of iii2 and iii3, on the other hand, are extremely small. in comparison to the reference populations, iii2 and iii3 these buccolingual breadths are extremely narrow. discussion all cases of bilateral fusion encountered here support the observations of barac and skrinjavic (1991), skrinjavic and barac (1991), ishida et al. (1990), hagam (1988), and gellin (1984). the independence between the processes determining the number of anterior teeth on each jaw is clear. in each case, fusion is only present in the mandible. tooth size on both upper and lower dentition appears to be affected. as anticipated, fusion is accompanied by an apparent crown size reduction expressed as reduced buccolingual dimensions in the deciduous dentition and lower crown heights in the permanent dentition. why this should affect both the upper and lower dentition is not clear. perhaps this lack table 4. mean mesiodistal diameters in the primary dentition of selected groups* maxillary maxillary maxillary maxillary group i1 i2 c c south african 6.47 5.32 7.08 6.02 japanese 6.70 5.53 6.70 5.88 native american 6.86 5.72 7.15 6.20 australian aborigine 7.40 6.19 7.41 6.44 european caucasian 6.60 5.46 7.04 6.04 american caucasian 6.40 5.24 6.88 5.92 average 6.74 5.58 7.04 6.08 iii2 6.10 5.58 6.90 6.00 iii3 6.30 5.59 7.50 6.90 *(grine 1986) table 5. mean buccolingual diameters in the primary dentition of selected groups* maxillary maxillary maxillary mandibular group i1 i2 c c african 4.98 4.85 6.16 5.48 australian aborigine 5.47 5.24 6.61 6.05 naisoi 5.15 4.79 5.91 5.31 american caucasian 5.13 4.71 6.11 5.6 mean 5.18 4.90 6.20 5.61 iii2 4.60 4.25 5.50 4.75 iii3 5.00 4.20 5.60 4.20 *(grine 1986) f.d. gurri and g. balam ��inheritance of fused teeth of independence between the upper and lower jaws with regard to tooth size is related to the generalized trend towards tooth reduction that accompanies oligodontia (garn, 1977). if this is the situation, fusion should not only be associated with frontal tooth reduction but third molar agenesis as well. although moody and montgomery (1934) did not differentiate between fusion and gemination, they described what appears to be unilateral fusion of the lower incisors. the pedigrees they present suggest that inheritance of the trait is controlled by a single dominant gene. however, the fact that their study showed only females inheriting and transmitting this trait make it difficult to establish its autosomal nature. in the study by saito (1959)—based on a large sample of infants, children and their families—the trait indeed seems to be transmitted as an autosomal dominant character. saito, however, did not distinguish between fusion and gemination when attempting to establish the mode of inheritance. the attendant confusion of including what may be two different genetic processes may also have led to his inference that the trait exhibited incomplete penetrance. the pedigree presented in the present paper, however, makes it clear that if bilateral fusion of fig. 2. fusion of the permanent lower incisors of individual ii1 (frontal view). fig. 3. fusion of the deciduous lower incisors of individual iii3. fusion is so advanced that, except for the exaggerated mesiodistal width, this case could be mistakenly classified as agenesis of the lateral incisors (frontal view). fig. 4. fusion of the deciduous incisors of individual iii2. his right incisor is the only one that shows some separation in this series (frontal view). fig. 5. fusion of the permanent lower incisors of individual iii6 (three-quarter view). the lower incisors is indeed the consequence of an autosomal dominant gene—as appears to be the case— this pedigree exhibits full penetrance. unfortunately, the present pedigree lacks a third generation from the side of the family that possesses the trait. the husband of the affected mother is not related to her, as far as could be determined, and no one in his family exhibits the trait. nevertheless, since the husband (ii3) is from the same home town as his affected wife (ii2), the possibility of inbreeding and the presence of a rare recessive allele cannot be completely ruled out. acknowledgments the authors wish to thank drs. della cook and robert meier from indiana university, department of anthropology, for their comments and corrections to the original manuscript. we would also like to thank dr. cook for photographing the dental casts, and dr. ernesto rico for making the casts. this investigation was supported by a grant from the instituto nacional indigenista de mexico. literature cited barac fv, skrinjaric i. 1991. double teeth in primary dentition and findings of permanent successors. 34 acta stomatol croat 25:39-43. bedi r, moody gh. 1992. a primary double molar tooth in a child with russell-silver syndrome. br dent j 171:284-286. bricker sl, martin r. 1987. bilateral gemination of maxillary permanent central incisor. oral surg oral med oral pathol 63:120. brook ah, winter gb. 1970. double teeth: a retrospective study of “geminated” and “fused” teeth in children. br dent j 129: 123-130. curzon ja, curzon mej. 1967. congenital dental anomalies in a group of british columbia children. j can dent assoc 33:554-558. dixon gh, stewart re. 1976. genetic aspects of anomalous tooth development. in: steward re, prescott g.h. editors. oral facial genetics. st. louis: c.v. mosby company, p 124-150. duncan wk, helpin ml. 1987. bilateral fusion and gemination: a literature analysis and case report. oral surg oral med oral pathol 64:82-87. garn sm. 1977. genetics of dental development. in: mcnamara ja, editor. the biology of occlusal development. ann arbor, michigan: the center for human growth and development, p 61-88. gellin me. 1984. the distribution of anomalies of primary anterior teeth and their effect on the permanent successors. dent clin north am 28:6980. grahnen h, granath le. 1961. numerical variations in primary dentition and their correlation with the permanent dentition. odont rev 12:348-357. grine fe. 1986. anthropological aspects of the deciduous teeth of south african blacks. in: singer r, lundy jk, editors. variation culture and evolution in african populations. johanesburg: witwatersand university press, p 47-83. gurri fd, balam g. 1992. regional integration and changes in nutritional status in the central region of yucatan, mexico: a study of dental enamel hypoplasia and anthropometry. j hum ecol 3:417432. hagam ft. 1988. anomalies of form and number, fused primary teeth, a correlation of the dentitions. asdc j dent child 55:359-361. hitchin ad, morris i. 1966. geminated odontomeconnation of the incisors in the dog its aetiology and ontogeny. j dent res 45:575-583. hosomit ym, yaoi m, sakiyama y, toda t. 1989. a maxillary central incisor having two root canals geminated with a supernumerary tooth. j endod 15:161-163. ishida r, mishima k, adachi c, miyamoto a, ooshima t, amari e, et al. 1990. frequency of developmental disturbances of tooth structure. shoni shikagaku zasshi 28:466-485. jarvinen s, lehtinen l, milen a. 1980. epidemiologic study of joined primary teeth in finnish children. comm dent oral epidemiol 8:201-202. killian cm, croll tp. 1990. dental twining anomalies: the nomenclature enigma. quintessence int 21:571576. levitas tc. 1965. gemination fusion, twinning and concrescence. asdc j dent child 32:93-100. mader cl. 1979. fusion of teeth. j amer dent assoc 98:62-64. maibaum ww. 1990. fusion of confusion? oral surg oral pathol 69:656-657. moody e, montgomery lb. 1934. hereditary tendencies in tooth formation. j am dent assoc 21:1774-1776. nik-hussein nn. 1989. bilateral symmetrical fusion of primary and permanent mandibular lateral incisors and canines. j pedod 13:378-383. nik-hussein nn, salcedo ah. 1987. double teeth and hypodontia in identical twins. asdc j dent child 54:179-181. o’reilly pm. 1989. a structural study and ultrastructural study of a fused tooth. j endod 15:442-446. o’reilly pm. 1990. structural and radiographic evaluation of four cases of tooth fusion. aust dent j 35:269-9. pindborg jj. 1970. pathology of the dental hard tissues. philadelphia: w.b. saunders company. reeh es, el deeb m. 1989. root canal morphology of fused mandibular canine and lateral incisor. j endod 15:33-35. saito ta. 1959. a genetic study on the degenerative anomalies of deciduous teeth. jap j hum genet 4:27-54. salem g. 1989. prevalence of selected dental anomalies in saudi children from gizan region. comm dent oral epidemiol 17:162-163. shafer wg, hine mk and levy bm. 1974. a textbook of oral pathology, 3rd ed. philadelphia: w.b. saunders company. skrinjaric i, barac fv. 1991. anomalies of deciduous teeth and finding in the permanent dentition acta stomatol croat 25:151-6. stevenson dr. 1983. human skeletal remains in archaeological testing at guices creek, stewart county, tennessee. memphis state university anthropological research center occasional papers no. 12. wong m. 1991. treatment considerations in a geminated maxillary lateral incisor. j endod 17:179-181. f.d. gurri and g. balam hasegawa et al. 2007.1 1 *correspondence to: yuh hasegawa, school of life dentistry at niigata, the nippon dental university, 1-8, hamaura-chou, chuuou-ku, niigata-city, niigata, japan 951-8580 e-mail: haseyu@ngt.ndu.ac.jp mongolia is a sparsely populated, landlocked country between russia and the people’s republic of china. the capital city is ulaanbaatar and the population is around 2.4 million. the mongol confederation was established by ghengis khan in 1206 but after the fall of the great mongolian empire, during the qing dynasty of china, tribal alignments became more rigid as they were incorporated into a more centralized administrative system imposed by the chinese. ethnohistorically, the mongolian population can be divided into four clusters comprising khalkha-mongols, western or oirat mongols, turkic speakers, and a northeastern cluster. the khalkha-mongols make up the majority of modern mongolians and they are dispersed throughout the country (chimge and batsuuri, 1999). it is well established that there are two patterns of dental variation in mongoloid populations. one is the sundadont pattern, typical of south-east asia, and the other is the sinodont pattern, typical of north-east asia. sundadonts whose teeth are relatively simple are thought to have retained dental features similar to those evident in late pleistocene populations. sinodonts were first recognized in a large skeletal series originating in northern china and are hypothesized to have evolved from the sundadont condition, developing a relatively more specialized and complex dental pattern. turner comparison of permanent mandibular molar crown dimensions between mongolians and caucasians yuh hasegawa1,2*, james r. rogers2, ikuo kageyama1, sen nakahara3, grant c. townsend2 1school of life dentistry at niigata, the nippon dental university, niigata, japan 2school of dentistry, the university of adelaide, adelaide, south australia, australia 3school of life dentistry at tokyo, the nippon dental university, tokyo, japan abstract the aims of this study were to compare crown dimensions of mandibular first molars (m1) and second molars (m2) between mongolians (belonging to the khalkha-mogol grouping) and caucasians (northern european ancestry) and to attempt to explain any observed differences in phylogenetic and ontogenetic terms. materials in this study comprised dental casts of 48 mongolian female subjects with a mean age of 20.5 years and 50 caucasian female subjects with a mean age of 21.5 years. for m1, the buccolingual diameters of both mesial and distal crown components in mongolians were significantly larger than in caucasians. for m2, the mesiodistal and buccolingual diameters of the (1990) observed this dental pattern in populations of northern china, mongolia, and southern siberia. even though frequencies of occurrence and degrees of expression of nonmetric morphological crown features have been described in many asian populations, including mongolians (scott and turner, 1998; turner, 1990; manabe et al., 2003), there have been only a few studies describing mesiodistal and buccolingual crown diameters in mongolians (matsumura, 1995; matsumura and hudson, 2005; hanihara, 2005). recently, more emphasis has been placed on describing how the various components of the dental crown contribute to overall crown size, with studies focussing on intracoronal components rather than traditional mesiodistal and buccolingual crown diameters. however, as far as we are aware, no such study has been carried out in mongolians. therefore, the aim of this study was to compare not only overall crown size but also the sizes of various crown components (i.e., talonid and trigonid) of mandibular distal crown components in the mongolian sample were significantly larger and the mesiodistal and buccolingual diameters of mesial components were significantly smaller compared with those of caucasians. common environmental effects, possibly related to the prenatal environment, as well as genetic influences, may be contributing to the differences in buccolingual dimensions of m1 between mongolians and caucasians. given that the m2 develops later and over a longer period of time than the m1, it is reasonable to assume that this tooth may be subject to greater environmental pressures than applied to the m1. dental anthropology 2007;20:1-6. 2 y. hasegawa et al. first and second molars between a sample of modern young female adult mongolians and a sample of female caucasians of similar ages, and to attempt to explain any observed differences in phylogenetic and ontogenetic terms. the study forms part of a larger investigation of the mongolian dentition being undertaken by researchers from the health science university of mongolia, mongolia, and the nippon dental university school of life dentistry, japan. materials and methods materials in this study comprised dental casts of 48 mongolian female subjects and 50 caucasian female subjects. the mongolian dental casts were produced from impressions collected by a survey team from the nippon dental university school of life dentistry, japan. this material is stored at the school of dentistry, health science university of mongolia, ulaanbaatar, mongolia. the ages of the mongolian subjects ranged between 18.4 and 25.0 years, with a mean age of 20.5 years. mongolian dental casts were collected from students attending colleges and universities in ulaanbaatar, who were born in ulaanbaatar or its suburbs and who belonged to the khalkha-mogol grouping. the caucasian dental casts are stored in the school of dentistry, the university of adelaide, and were obtained from dental students between 20.8 and 24.5 years, with a mean age of 21.5 years. for the caucasian group, only those students with northern european ancestry were chosen. dental casts were used only if mandibular first and second molars (m1 and m2) had no caries, no dental treatment, no anomaly of crown morphology, and only if the cusp tips, central pits and occlusal grooves were not noticeably affected by tooth wear. according to ethical standards, it was necessary for mongolian students to be told the purpose of the study and agreements were obtained from them before impressions for dental casts were taken. casts of the dentitions of the adelaide students were obtained as part of their dental course requirements and were selected from a larger collection. m1 and m2 were measured using a pair of sliding digital calipers to an accuracy of 0.05 mm. the selected dimensions of the tooth crowns that were measured are shown in figure 1. the methods adopted to measure mesiodistal and buccolingual crown diameters were as described by fujita (1949). mesiodistal crown diameters of the trigonid and talonid were recorded as described by yamada (1992), and buccolingual crown diameters of the trigonid and talonid followed the definitions given by kondo et al. (1998). a suggestion made by yamada (1992) was adopted to make it possible to define the border between the trigonid and talonid by defining the midpoint between the mesial central fossa and the intersection of the buccal groove. comparisons of mean values for mandibular molar crown dimensions between the mongolian and caucasian samples were made using student’s t-test. f-tests were used to compare variances. statistical significance was set at alpha = 0.05. descriptive statistics including distribution parameters were calculated with statview (sas institute, version 5.0 for macintosh). measurement errors were analyzed by a procedure of double determination measurements using paired t-tests (statistical significance set at alpha = 0.05) for systematic errors and the method described by dahlberg (1940) for random errors. results with reference to systematic errors, there were significant differences between first and second measurements for the following dimensions: in the mongolian sample: tlmd for the right m1, trmd for the left m1, and tlmd and trmd for the left m2 in the mongolian sample; md, bl and tlbl for the right m1, md, and tlbl for the right m2 in the caucasian sample. however, the magnitudes of mean differences between first and second determinations were relatively small, ranging from 0.01 to 0.21 mm. random measurement errors ranged from 0.09 to 0.22 mm and these values were very small in magnitude compared with the mean values. therefore, it was confirmed that errors of the method were relatively small and unlikely to bias results. fig. 1. tooth crown dimensions selected for measurements. abbreviations: bl, buccolingual diameter; md, mesiodistal diameter; trbl, buccolingual diameter of trigonid; trmd, mesiodistal diameter of trigonid; tlbl, buccolingual diameter of talonid; tlmd, mesiodistal diameter of talonid. tl b l tr b l md b l tlmdtrmd buccal m es ia l �mandibular molar crown dimensions table 1. descriptive statistics of crown diameters in the mandibular first molar (mm) mongolian (female) caucasian (female) n mean sd cv (%) significance n mean sd cv (%) right side md 48 10.93 0.50 4.6 ns 50 10.69 0.63 5.9 tlmd 48 6.23 0.55 8.8 ns 50 5.99 0.59 9.8 trmd 48 4.69 0.29 6.3 ns 50 4.70 0.35 7.6 bl 48 10.51 0.39 4.3 ** 50 10.25 0.46 4.5 tlbl 48 10.43 0.45 4.4 * 50 10.16 0.48 4.7 trbl 48 10.31 0.45 7.5 ** 50 10.05 0.52 5.2 left side md 48 10.96 0.51 4.6 ns 50 10.73 0.61 5.7 tlmd 48 6.27 0.51 8.2 ns 50 6.12 0.61 10.0 trmd 48 4.69 0.38 8.0 ns 50 4.61 0.38 8.3 bl 48 10.52 0.39 3.9 ** 50 10.28 0.49 4.8 tlbl 48 10.40 0.40 3.5 * 50 10.21 0.51 5.0 trbl 48 10.36 0.36 6.9 ** 50 10.11 0.48 4.7 ns: not significant *0.05 > p > 0.01; **p < 0.01 cv = (sd / mean) 100 table 2. descriptive statistics of crown diameters in the mandibular second molar (mm) mongolian (female) caucasian (female) n mean sd cv (%) significance n mean sd cv (%) right side md 48 10.12 0.75 7.4 ns 50 10.15 0.61 6.1 tlmd 48 5.18 0.62 12.0 ** 50 4.81 0.48 10.0 trmd 48 4.94 0.38 7.7 ** 50 5.34 0.48 9.0 bl 48 10.07 0.47 4.7 * 50 9.82 0.62 6.3 tlbl 48 9.93 0.53 5.4 ** 50 9.44 0.60 6.4 trbl 48 9.89 0.54 5.4 ns 50 9.73 0.69 7.1 left side md 48 10.05 0.69 6.9 ns 50 10.11 0.62 6.2 tlmd 48 5.12 0.59 11.6 * 50 4.89 0.55 11.3 trmd 48 4.93 0.37 7.5 ** 50 5.22 0.43 8.3 bl 48 10.08 0.43 4.3 ns 50 9.94 0.62 6.3 tlbl 48 9.92 0.46 4.6 ** 50 9.51 0.69 7.3 trbl 48 9.95 0.49 4.9 ns 50 9.89 0.64 6.5 ns: not significant *0.05 > p > 0.01; **p < 0.01 cv = (sd / mean) 100 4 comparisons between right and left side measurements of m1 and m2 were made using paired t-tests (statistical significance set at alpha = 0.05). in the mongolian sample, there was no significant difference between sides but, in the caucasian sample, there were significant differences between right and left sides, namely for tlmd and trmd of m1, and trmd, bl and trbl of m2. the magnitude of differences ranged from 0.03 to 0.12 mm. table 1 shows basic descriptive statistics of crown diameters in the mongolian and caucasian samples for m1. when consideration was given to mesiodistal crown diameters, there was no significant difference between mongolian and caucasian samples on either right or left sides. however, all the buccolingual crown diameters of the mongolian sample were significantly larger than those of caucasians; that is, bl, tlbl and trbl were all larger. coefficients of variation showed that tlmd, trmd and trbl displayed the greatest variation in the mongolian sample, and tlmd and trmd also displayed high relative variability in the caucasian sample. table 2 shows basic descriptive statistics of crown diameters in mongolian and caucasian samples for m2. two dimensions displayed statistically significant differences between the samples: tlmd was significantly larger in mongolians than in caucasians, whereas trmd was significantly smaller in mongolians than in caucasians. however, there was no significant difference between mongolian and caucasian samples in md dimensions. with reference to the buccolingual crown diameters, there was a significant difference only for bl on the right side between the mongolian and caucasian samples. tlbl in mongolians was significantly larger than those of the caucasians but there was no statistically significant difference between the samples for trbl. coefficients of variation showed that md, tlmd and trmd displayed high relative variation in mongolians and tlmd, trmd also displayed high coefficients of variation in caucasians. table 3 shows basic descriptive statistics of reduction indices of crown measurements for m2 compared with m1 in the mongolian and caucasian samples. for reduction indices of mesiodistal crown dimensions, there were two significant differences between mongolian and caucasian samples, namely md and trmd. both were significantly smaller in mongolians compared with caucasians but the reduction index of md was less than 100 whereas that for trmd was over 100—indicating a reduction for md but an enlargement for trmd of m2 relative to m1. the values of reduction indices for tlmd were the lowest of all variables, indicating that the largest reduction in size from m1 to m2 occurred in tlmd in both mongolian and caucasian samples. for buccolingual crown dimensions, there was no significant difference in the mean value of reduction indices for bl between mongolian and caucasian samples. however, there was a significant difference in the mean reduction index of tlbl between samples, with the mean value being lower in caucasians. there was also a significant table 3. descriptive statistics of reduction indices (%) for the mandibular second molar mongolian (female) caucasian (female) n mean sd cv (%) significance n mean sd cv (%) right side md 48 92.61 4.91 5.3 ** 50 94.99 3.36 5.9 tlmd 48 83.31 8.95 10.7 ns 50 80.62 7.62 9.8 trmd 48 105.58 9.04 8.6 ** 50 113.86 9.32 7.6 bl 48 95.77 3.15 3.3 ns 50 95.87 3.93 4.5 tlbl 48 95.29 3.50 3.7 ** 50 92.91 4.27 4.7 trbl 48 95.96 4.00 4.2 ns 50 96.79 4.52 5.2 left side md 48 91.74 4.68 5.1 ** 50 94.20 3.94 4.2 tlmd 48 81.71 7.04 8.6 ns 50 80.21 8.62 10.8 trmd 48 105.56 8.00 7.6 ** 50 113.59 10.33 9.1 bl 48 95.85 2.76 2.9 ns 50 96.72 3.48 3.6 tlbl 48 95.37 2.88 3.0 ** 50 93.09 4.34 4.7 trbl 48 96.02 3.30 3.4 ** 50 97.76 3.43 3.5 ns: not significant *0.05 > p > 0.01; **p < 0.01 cv = (sd / mean) 100 y. hasegawa et al. 5 difference for reduction indices of trbl on the left side only between mongolian and caucasian samples. discussion the lower first molar begins to form around 30 weeks in utero and crowns have completed their formation at approximately three years after birth. in contrast, lower second molars commence to form around three years after birth and their crowns are fully-formed by approximately seven years (christensen and kraus, 1965; oka and kraus, 1969). most permanent lower molars have five cusps: mesiobuccal, mesiolingual, distobuccal, distolingual, and distal. during formation the mesiobuccal cusp is always the first to start development, followed by mesiolingual, distobuccal, and then the distolingual. the last component of the crown to form is the distal cusp (christensen and kraus, 1965; hillson, 1996). the trigonid consists of the mesiobuccal and mesiolingual cusps, while the talonid consists of the distobuccal, distolingual and distal cusps. in four-cusped molars, the distal cusp is missing. our study has shown that bl, tlbl and trbl dimensions in m1 of the mongolian sample were significantly larger than those of the caucasian sample. in contrast, there was no significant difference in the md, tlmd and trmd dimensions. thus, there was a significant size difference in buccolingual dimensions but not in mesiodistal dimensions between the two samples. tooth size variability appears to have a strong genetic component, but environmental factors are also of importance (dempsey and townsend, 2001). indeed, there is evidence that common environmental contributions to tooth size variability are greater for buccolingual dimensions than mesiodistal ones (townsend and brown, 1978). the buccolingual diameters of both the talonid (distal part of the crown) and trigonid (mesial part of the crown) of m1 in mongolians were significantly larger than in caucasians. this suggests that common environmental effects, possibly related to the prenatal environment, as well as genetic influences, may be contributing to the differences in buccolingual dimensions between mongolians and caucasians. for m2, there were significant differences between mongolians and caucasians for tlmd, trmd, right bl and tlbl. the mean values for tlmd, trmd and tlbl differed by around 5% whereas the difference in the means for bl (right side only) between mongolians and caucasians was around only 2%. the diameters of the talonid (tlmd and tlbl) of mongolians were significantly larger than those of caucasians. on the other hand, trmd in mongolians was significantly smaller than in caucasians. furthermore, there was no significant difference in trbl. thus, the mesiodistal and buccolingual diameters of the distal part of tooth crown in the mongolian sample were significantly larger and the mesiodistal and buccolingual diameters of mesial part were significantly smaller compared with those of caucasians. it is difficult to explain why this differential effect exists. it may be due to an interaction between these two crown components during development, with larger earlier-forming components being associated with smaller later-developing components. alternatively, the finding could be due to chance variation associated with a small sample size. the last tooth to develop in each class tends to be the most variable in size and shape (dahlberg, 1945). this variability is thought to be due to greater environmental influence during development linked to a decrease in intrinsic genetic control over tooth size from the early to the late developing teeth within each class (sofaer et al., 1971). given that the m2 develops later and over a longer period of time than the m1, it is reasonable to assume that this tooth may be subject to greater environmental pressures than would be applied to the m1. indeed, the dimensions of m2 tended to display more variation, as evidenced by the values of cvs, than those of m1. the m2 develops later than the m1, therefore, environmental influences acting an each population may have contributed more to size variation than genetic factors for m2 compared with m1. the reduction indices of md and trmd were significantly smaller in the mongolian sample compared with caucasians. this indicates that overall mesiodistal crown size of m2 in mongolians, and also the mesiodistal size of the trigonid, are more reduced compared to m1. in contrast, the reduction indices for trmd did not differ significantly between the samples. the reduction index for tlbl was larger in mongolians, confirming that this dimension did not reduce as much in m2 compared with m1 as it did in caucasians. our results are consistent with the findings of kondo et al. (2005) and show a tendency for increasing size in the mesial component of molar crowns and decreasing size in the distal component when comparing m2 to m1. they are also consistent with the findings of yamada (1992) who noted that the distal part of molars was most affected by morphological variations, including tooth size reduction. in the maxillary molars, the mesiobuccal cusp generally increases in size from m1 to m2 and reduces from m2 to m3. the mesiolingual cusp follows a pattern similar to that of the mesiobuccal, whereas the distobuccal cusp shows a marked reduction in size from m1 to m3 (macho and moggi-cecchi, 1992). it would seem that there are also interactions between the mesial and distal crown components of maxillary molars as well as mandibular ones. the mesial crown component may tend to become larger to maintain the occlusal surface area of m2 as the distal component is reduced. a broader occlusal surface is likely to be advantageous for masticatory activity (e.g., crushing and/or grinding food), and the enlargement of mesial crown component makes the occlusal surface broader as overall tooth size mandibular molar crown dimensions � is reduced. overall molar crown size and intra-coronal components showed differential patterns of reduction in the two study samples, as has been shown between other living human populations (kanazawa et al., 1985; kondo et al., 2005). this study has investigated the size relationships between the talonid and trigonid of m1 and m2 in mongolian and caucasian samples. sexual dimorphism was not explored in this study but it is planned to collect data from male mongolians in the future. once we have gained greater knowledge of tooth size variation in mongolians, it will be of interest to compare tooth size in mongolians with japanese, bearing in mind that both groups share a sinodont dental pattern. acknowledgements we are grateful for the assistance of associate professor shintaro kondo who made valuable suggestions regarding study methods. we are also indebted to the staff of the schools of dentistry of both the health science university of mongolia and the university of adelaide. the dental casts of mongolians used in this study were collected during a dental anthropological survey in 2006. the dental casts of caucasians used in this study were collected from the students of the school of dentistry, the university of adelaide, from 1982 to 1991. literature cited chimge n, batsuuri j. 1999. interethnic genetic differentiation: hla class i antigens in the population of mongolia. am j hum biol 11:603-618. christensen gj, kraus bs. 1965. initial calcification of the human permanent first molar. j dent res 44:13381342. dahlberg aa. 1945. the changing dentition of man. j am dent assoc 32:676-690. dahlberg g. 1940. statistical methods for medical and biological students. london: george allen and unwin ltd. dempsey pj, townsend gc. 2001. genetic and environmental contributions to variation in human tooth size. heredity 86:685-693. fujita t. 1949. on the standard of the measurement of teeth. j anthropol soc nippon 61:27-32 (in japanese with german summary). goyal hd. 1999. a development perspective on mongolia. asian survey 39:633-655. hanihara t, ishida h. 2005. metric dental variation of major human populations. am j phys anthropol 128:287-298. hillson s. 1996. dental anthropology. cambridge, england: cambridge university press. kanazawa e, sekikawa m, akai j, ozaki t. 1985. allometric variation on cuspal areas of the lower first molar in three racial populations. j anthropol soc nippon 93:425-438. kondo s, funatsu t, amino s, sasa r, wakatsuki e. 1998. an odontometrical analysis of the mandibular molariform teeth in the japanese males. pediatr dent j 8:73-77 kondo s, townsend gc, nakajima k, yamada h, wakatsuki e. 1999. size of crown components of the mandibular deciduous and permanent molars in australian aborigines. in: mayhall jt, heikkinen t, editors. dental morphology 1998. oulu, finland: oulu university press. p 150-156. kondo s, townsend gc, kanazawa e. 2005. size relationships among permanent mandibular molars in aboriginal australians and papua new guinea highlanders. am j hum biol 17:622-633. macho ga, moggi-cecchi j. 1992. reduction of maxillary molars in homo sapiens sapiens: a different pespective. am j phys anthropol 87:151-159. manabe y, oyamada j, kitagawa y, rokutanda a, kato k, matsushita t. 2003. dental morphology of the dawenkou neolithic population in north china: implications for the origin and distribution of sinodonty. j hum evol 45:369-380. matsumura h. 1995. dental characteristics affinities of the prehistoric to the modern japanese with the east asians, american natives and australo-melanesians. anthropol sci 103:235-261. matsumura h, hudson mj. 2005. dental perspectives on the population history of southeast asia. am j phys anthropol 127:182-209. oka sw, kraus bs. 1969. the circumnatal status of molar crown maturation among the hominoidea. arch oral biol 14:639-659. scott gr, turner cg ii. 1988. dental anthropology. ann rev anthropol 17:99-126. sofaer ja, bailit hl, maclean cj. 1971. a developmental basis for differential tooth reduction during hominid evolution. evolution 25:509-517. sofaer ja. 1973. a model relating developmental interaction and differential evolutionary reduction of tooth size. evolution 27:427-434. townsend gc, brown t. 1978. heritability of permanent tooth size. am j phys anthropol 49:497-504. turner cg ii. 1990. major features of sundadonty and sinodonty, including suggestions about east asian microevolution, population history, and late pleistocene relationships with australian aboriginals. am j phys anthropol 82:295-317. van valen l. 1962. growth field in the dentition of peromyscos. evolution 16:272-277. yamada h. 1992. on the “talonid” in japanese lower molars. jpn j oral biol 34:15-24 (in japanese with english summary). y. hasegawa et al. harris 2005.2 43 dental anthropologists—building on classic anatomical nomenclature—have a precise lexicon of terms for designating specific teeth. there is, for example, no confusion when describing a human’s “permanent maxillary right central incisor.” such labels are, however, lengthy and cumbersome, no more so than in the dental clinical setting where a dentist needs to expeditiously document voluminous details on numerous patients in a concise manner (schwartz and stege, 1977). the practical need for conciseness, precision and brevity has led clinicians to develop a variety of tooth coding systems, some of which are intuitive while others are refractory without some clues. the purpose of this note is to delineate the common clinical systems of tooth coding in order to familiarize dental anthropologists with the clinical nomenclature. permanent dentition it is common knowledge that the adult human dentition consists of 32 teeth arrayed into four morphological classes in each quadrant (e.g., todd, 1918; legros clark, 1959). this leads to the dental formula i 2 2 c 1 1 p 2 2 m 3 3 or, simply, 2 1 2 3 2 1 2 3 which is a symbolic denotation that there normally are 2 incisors, 1 canine, 2 premolars, and 3 molars in each of the four quadrants of the mouth. the etymologies of these dental terms are all from the latin. incisor (l. incidere = to cut into) alludes to the incisors’ function of incising and nipping; incisors are the “cutting teeth.” canines (l. canis = dog, hound) derives from the prominent, well-developed teeth in the family canidae (dogs), though their value for prehension has been considerably diminished in humans, where these teeth function essentially as incisors. most clinical dentists use the term cuspid in place of canine, since tooth-coding systems in the clinical dental setting edward f. harris* department of orthodontics, university of tennessee, memphis, tennessee these teeth normally consist of one large primary cusp. “premolars” merely recognizes the anatomical position of these teeth in front of the molars. clinicians commonly use the term bicuspid in place of premolar, since these teeth commonly (but certainly not always) possess two cusps (cf. kraus and furr, 1953). molars (l. molaris = millstone) refers to the grinding, triturating function of these teeth with their substantial occlusal surfaces. zsigmondy-palmer system the most popular system of tooth designation for much of the 20th century was developed by the viennese dentist adolph zsigmondy (zsigmondy, 1861, 1874). he broke with tradition, substituting numbers for the eight teeth in each quadrant in place of the lengthy latin names in use to that time (schwartz and stege, 1977; peck and peck, 1993). the correspondence is: 1 ...................... central incisor 2 ...................... lateral incisor 3 ...................... canine (cuspid) 4 ...................... first premolar (bicuspid) 5 ...................... second premolar (bicuspid) 6 ...................... first molar 7 ...................... second molar 8 ...................... third molar (dens sapientiae; wisdom tooth) zsigmondy combined his tooth numbering system with a graphical device to specify the quadrant of the mouth. an l-shaped mark ( ) was used, with the *correspondence to: edward f. harris, department of orthodontics, college of dentistry, the health science center, 875 union avenue, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu abstract clinical dentists have developed a variety of tooth-coding systems for efficiently recording a patient’s dental status. the coding systems may not be self-evident to dental anthropologists lacking dental training. the purpose of this note is to review the tooth designation systems currently in common use. the nature of the charting systems and brief historical origins of three systems are reviewed, namely (1) the zsigmondy-palmer system that is becoming largely of historical interest, (2) the universal system that is common in the united states, and (3) the fdi two-digit system that has been adapted throughout the rest of the world. use of these three systems is described for the permanent and primary dentitions. dental anthropology 2005;18(2):43-49. 44 vertical line segment being the subject’s midline and the horizontal segment his occlusal plane that separates the upper and lower arcades. the clinician could, then, easily code a specific tooth, such as the lower left canine 3 or the upper right first molar 6 . confusion is pretty much limited to the novitiate’s need to remember that the codes refer to the patient’s left or right side. history then becomes a bit conflicted because the ohio dentist corydon palmer (palmer, 1870, 1891) argued for his independent invention of the same coding system. palmer contended that the natural division of the dentition into quadrants was a well-known, obvious device (fig. 1). indeed, palmer was quite testy in his 1891 paper that he be given all credit for the scheme’s development (fig. 2). the quadrant is denoted by the shape of the symbol, like for mandibular left, and the tooth position is numbered from 1 (central incisor) through 8 (third molar). the scheme has a naturalness and simplicity such that independent invention seems probable. in any event, most american dentists have been taught the notation as being palmer’s (though also termed the “quadrant system” by some; sharma and wadhwa, 1977). the palmer system also has been labeled the “angular system” and the “grid system” because of the horizontal and vertical line segments that denote the tooth’s quadrant. the obvious down-side of the zsigmondy-palmer notation is that, while it is easy to sketch the tooth codes in a patient’s record, it is tedious to type or verbalize them. for instance, there is no word for the symbol or . gustafson (1966), o’connor (1983) and others have commented that palmer’s angle symbol denoting side and arch probably was the system’s undoing. while it is no effort at all to jot down 5 or 7 in a patient’s record, there is no natural analog for 3 with an embedded digit on a typewriter or word-processor. indeed, it was the need to computerize the dental recording system that marshaled-in the fdi system—and incidentally promoted the use of the universal system in the united states. coding a tooth numerically, as #16 or 28, lends itself to word processing. desiderata there are a few other items of note that developed contemporaneous with zsigmondy and palmer but do not warrant full-blown descriptions here. the latin terms e.f. harris fig. 1. facsimile of a diagram by palmer (1891) showing the division of the dentition into four quadrants. the vertical and horizontal line segments are used in this charting method to specify a tooth’s quadrant. facing the patient, as here, the quadrants are numbered clockwise from the upper left of the figure, so the patient’s quadrants are (1) upper right, (2) upper left, (3) lower left, and (4) lower right. fig 2. the zsigmondy-palmer tooth designation system, where lines define the four quadrants and the teeth are numbered from 1 to 8 in each quadrant (modified from palmer, 1891). 45 superiore (sup.) and inferiore (inf.) will be encountered in the older literature, referring to the maxillary and mandiblar jaws, respectively. likewise, the latin words dextral (dext.) and sinistral (sin.) commonly were used to denote a tooth in the right or left arcade, respectively. so, for example, de terra (1905:5) uses the code “i1 sup. sin.” to denote the maxillary left i1 (central incisor). also, haderup’s (1891) tooth designation system experienced popularity for some decades after its introduction. in place of zsigmondy’s angle (e.g., ), haderup used a plus sign (+) to denote a maxillary tooth and a minus sign (–) for a mandibular tooth, and the sign was placed mesial to the tooth being referred to, so a right upper second molar would be 7+ and a left lower first premolar would be –4. fdi system dentists throughout the world—notably excepting the united states—now use the fdi two-digit system (fédération dentaire internationale). this scheme was developed by a “special committee on uniform dental recording” and passed as a resolution of the fdi general assembly at its 1970 meeting in bucharest, romania (keiser-nielsen, 1971a,b,c). while the fdi labeled this the “two-digit system,” it is more commonly referred to as the fdi system. it is useful to consider the five critefig. 3. the fdi two-digit scheme for tooth designations of the permanent dentition. the view is oriented as if you are looking at the subject, so the person’s right side (quadrants 1 and 4) are to the left of the page. fig. 4. the universal scheme for tooth designations of the permanent dentition. clinical tooth designation systems 46 e.f. harris ria that, according to the committee, are attained by this two-digit system of designating teeth: 1. simple to understand and to teach. 2. easy to pronounce in conversation and dictation. 3. readily communicable in print. 4. easy to translate into computer output. 5. easily adapted to standard charts used in general practice. as diagrammed in figure 3, the first digit denotes the quadrant of the mouth, the second digit defines the tooth’s normal position in the mouth, front to back. in all of these systems, the tooth’s “number” is its normal, expected position in the arch. expectation is that there are two incisors, one canine, two premolars, and three molars in each quadrant. “missing” teeth (due to congenital absence, impaction, extraction, etc.) are taken into account when identifying a tooth’s number. when a tooth is not present, its designation has to be determined from the positions of the extant teeth. for example, permanent mandibular second premolars are congenitally absent in roughly 3% of modern humans (stritzel et al., 1990; larmour et al., 2005), but determination of whether it actually is the first or second premolar that is missing in a particular case depends on the clinician’s differential diagnosis based on teeth that are present and related criteria. conversely, there is no accommodation in any of these systems for supernumerary teeth; these rare events are simply written-out in the chart. most dentists, as with most dental anthropologists, are right handed, so quadrant 1 (maxillary right) is closest to the dentist when examining a patient and is scored first, then the upper left quadrant, then one drops down to the lower left quadrant, finishing with teeth in the lower right quadrant (fig. 1). more formally, the quadrants are numbered “in a clockwise sequence … starting on the upper right side” when viewing the subject from fig. 5. the palmer tooth designation system for the primary dentition. the five tooth types in each quadrant are denoted by letters. the quadrant is coded by using the symbol , , , or . upper right upper left e d c b a a b c d e 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 e d c b a a b c d e lower right lower left fig. 6. arrangement of the permanent tooth codes in the zsigmondy-palmer system along with the corresponding codes (letters) for the primary teeth. such a chart is commonly found in older dental settings (sharma and wadhwa, 1977), though it is being upgraded to the more easily computerized universal or fdi systems. 47clinical tooth designation systems the front (keiser-nielsen, 1971a:105). this is to say that the upper right side (quadrant 1) is the patient’s upper right side. the fdi’s description also suggests how to verbalize the system, namely “the digits should be pronounced separately; thus, the permanent canines are teeth one-three, two-three, three-three, and four-three” (1971a:1034). the fdi committee fully recognized that it was combining zsigmondy-palmer’s tooth numbering system with the prefix number denoting the quadrant. the committee termed this a “compromise” system. the committee also pointed out that its quadrantnumbering sequence adopted the same pattern used by the universal system, making it familiar to u.s. dentists. with this logical system, there is no ambiguity as to side, quadrant, or arcade. universal numbering system what has become the universal system was proposed by j. perreidt in 1882. perreidt disliked the redundancy and potential confusion of zsigmondy’s use of tooth numbers 1 through 8 in all four quadrants. instead, he numbered the permanent teeth 1 through 32, starting at the upper right and continuing to the upper left, then the lower left to the lower right (fig. 4). the main benefit is that zsigmondy and palmer’s angular symbol ( ) is irrelevant, each tooth having its unique numerical designation. today, the “universal”system of tooth-coding is an interesting misnomer, because it is only used in the united states. the ada (american dental association) by a unanimous decision of its council on dental care programs adopted the universal system of numbering teeth on april 18, 1975 (schwartz and stege, 1977). numerous dentists subsequently have editorialized about the unnatural, illogical nature of the universal system— not to mention the unheeded complaints from fledgling dental students. the universal system is disarmingly simple in concept, just number the 32 permanent teeth from 1 through 32 (fig. 4). the difficulty is in learning to associate specific teeth with their numbers. once learned, of course, the system is effortless. starting with the third molar in the upper right quadrant (tooth #1), the teeth are numbered around the arch so the maxillary left third molar is tooth #16. one then drops down to the mandibular left third molar (#17) and numbers the teeth around the lower arcade, finishing with the mandibular right third molar (#32). there is no easy way to relate these 32 numbers to the natural, anatomic arrangement of the teeth. there is, for instance, no way to know intuitively that the second premolars are #4, #13, #20 and #29. one simply has to learn the system by rote. the compelling value of the universal system (as with the fdi system) is the ease of computerizing the data, which is its singular selling point for automating office systems (“paperless offices”), completing insurance and other third-party reimbursement forms (certainly a financial incentive), and accelerating communication (providing that both parties understand the codes). with both the fdi and universal systems, each tooth has a unique identifier. this can be invaluable when irreversible procedures such as extractions or endodontic treatment are requested by one dentist from another. primary dentition the primary teeth are ephemeral in that they only fig. 7. the universal system for the primary dentition, coding each tooth with a letter. as with all of these systems, the orientation refers to the patient’s own right and left sides, so the patient’s maxillary right quadrant is to the upper left of this diagram. 48 need to function for a few years before being replaced by (generally) larger and better-constructed permanent teeth with greater longevity. typically, the first primary teeth (the incisors) erupt through the oral mucosa at 7 or 8 months of age (e.g., tanguay et al., 1984), and the last primary teeth are exfoliated around 12 years of age, when the primary molars are replaced by the permanent premolars (e.g., hurme, 1949; moorrees et al., 1963). there are 20 succedaneous permanent teeth that “succeed” and replace the 20 primary teeth; the three permanent molars in each quadrant erupt distal to the primary teeth, so they are additional rather than replacement dental elements. “primary” would seem to be the preferred term here, but common synonyms are the deciduous teeth, the baby teeth, and the milk dentition. morphologically, the 20 primary teeth are categorized into three tooth types, incisors, canines, and molars, with the dental formula of 2:1:2 in each quadrant. fewer clinical coding systems have been developed for the primary dentition, but there still are plenty to provide confusion for the uninitiated. the three systems analogous to those described above for the permanent dentition are presented here. palmer analog. letters have commonly been used to denote the primary teeth; some systems use lower-case letters (perhaps mimicking the subadult nature of these teeth; churchill, 1932), but capital letters are encountered more often (fig. 5). again, the side and arcade are denoted by line segments: b is the maxillary right lateral incisor, and e is the mandibular left second molar. primary teeth have also been designated by roman numbers (i—v), which can further confuse the novice (churchill, 1932; sharma and wadhwa, 1977), particularly since still other systems have used roman numerals to designate quadrants in the permanent dentition. a chart as in figure 6 commonly is used in dental offices, and inspection shows that the numerals conform to palmer’s notation for the permanent teeth. while the capital letters are for the primary teeth. universal system. the 20 primary teeth are coded alphabetically from a through t (fig. 7). there is no anatomic parallel with this system. one simply has to memorize the system by rote. if using this system infrequently, it helps to remember that a, j, k and t are the second molars (at the distal ends of the quadrants) and that e, f, o and p are the central incisors. since there are only five teeth per quadrant, one can generally visualize the other tooth codes. fdi system. so much clinical attention is spent on the permanent teeth that they are coded as quadrants 1 through 4. the convention is to use numbers 5 through 8 to code the four primary quadrants even though they develop first (fig. 8). this numerical oddity was the subject of considerable discussion by the fdi committee, but it was reasoned that, “mainly because deciduous teeth function for such a short time in comparison with permanent teeth that the bulk of dental data to be collected and computerized in the future would obviously concern permanent teeth” (keiser-nielsen, 1971a:1035). overview there are two major motivations to develop a tooth-coding system. one is to conserve energy and communicate telegraphically. writing or speaking (or typing) “the permanent mandibular right second premolar” is much more taxing than referring to this tooth as #29 or 45, especially if teeth consume one’s professional life. there is the need to be specific but also to be as concise as practical. the other, recent driving force is to computerize ever-increasing masses of data, fig. 8. the fdi system for the primary dentition. quadrants for the primary dentition are numbered 5 through 8. quadrant numbers 1 through 4 are used for the permanent dentition, primarily because the dentist’s attention on the permanent dentition is so much greater than with the primary dentition. e.f. harris 49 and numeric codes (and their alphabetic equivalents) lend themselves to this end. the greatest emphasis has been from third-party payment systems with the need for the dentist to code the services rendered for reimbursement. one minor spin-off of the trend toward globalization is the need for standardization—so all of the participants understand the same set of “rules” and can communicate effectively. the fdi system seems to be the solution in terms of dental-coding systems. this leaves the u.s. “universal” system as an anachronism, but it doubtlessly will persist as a system paralleling the fdi system until the u.s. also converts to the metric system—which is moving glacially, at best. in scientific circles, though, an increasing number of dental journals is requiring its authors to use of the fdi system for tooth designations. only the three most common and long-lived systems are described here. numerous others have been proposed and may be encountered (see reviews in gustafson, 1966, and schwartz and stege, 1977). references cited churchill hr. 1932. human odontography and histology. philadelphia: lea & febiger. gustafson g. 1966. forensic odontology. new york: american elsevier publishing company, inc. hurme vo. 1949. ranges of normalcy in the eruption of permanent teeth. j dent child 16:11-15. keiser-nielsen s. 1971a. fédération dentaire internationale two-digit system of designating teeth. int dent j 21:104-106. keiser-nielsen s. 1971b. two-digit system of designating teeth. br dent j 130:215-216. keiser-nielsen s. 1971c. federation dentaire internationale. j amer dent assoc 82:1034-1035. kraus bs, furr ml. 1953. lower first premolars. i. a definition and classification of discrete morphologic traits. j dent res 32:554-564. larmour cj, mossey pa, thind bs, forgie ah, stirrups dr. 2005. hypodontia—a retrospective review of prevalence and etiology. quintessence int 36:263-270. le gros clark we. 1959. the antecedents of man. new york: harper & row. moorrees cfa, fanning ea, hunt ee jr. 1963. formation and resorption of three deciduous teeth in children. am j phys anthropol 21:205-213. o’connor jt. 1983. let’s really standardize our tooth numbering system. oper dent 8:73-74. palmer c. 1891. palmer’s dental notation. dent cosmos 33:194-198. peck s, peck l. 1993. a time for change of tooth numbering systems. j dent ed 57:643-647. parreidt j. 1882. zählung der zähne und benennung der verschiedenen zahnsorten. zahnärzliche mitteilungen aus der chirurgischen universitätspoliklnik zu leipzig, arthur felix, p 10-15 [cited in gustafson, 1966]. schwartz s, stege d. 1977. tooth numbering systems: a final choice. ann dent 36:99-106. sharma ps, wadhwa p. 1997. evaluation of the fdi twodigit system of designating teeth. quintessence int 10:9-101. stritzel f, symons al, gage jp. 1990. agenesis of the second premolar in males and females: distribution, number and sites affected. j clin pediatr dent 15:3941. tanguay r, demirjian a, thibault hw. 1984. sexual dimorphism in the emergence of the deciduous teeth. j dent res 63:65-68. de terra m. 1905 beitrage zu einer odontographie den menschenrassen. berlin: berlinishche verlagsanstalt. todd tw. 1918. an introduction to the mammalian dentition. st louis: cv mosby company. zsigmondy a. 1861. grundzüge einer praktischen methode zur raschen und genauen vormerkung der zahnärztlichen beobachtungen und operationen. deutsch viertel zahnhk 1:209-211. zsigmondy a. 1874. a practical method for rapidly noting dental observations and operations. br j dent sci 17:580-582. clinical tooth designation systems a brief survey g. richard scott and i are updating the history of dental anthropology that appeared in our 1988 review article on dental anthropology in the annual review of anthropology, and in the history section of our 1997 book, the anthropology of modern human teeth. we would like to add a table indicating who is teachin dental antrhopology and where the courses are being taught. the dental anthropology association membership seems like the best group at which to direct such an inquiry. if you have in the last 15 years taught a course titled dental anthropology, or an anatomical or osteological course with a significant dental anthropology component, could you please let us know. you can either e-mail me, or fill out the enclosed questionnaire. if you use the questionnaire, please return to dr. christy g. turner ii, 2208 n. campo alegre dr., tempe, az 85287-1105. in the latter case, if you have a short syllabus, we would be grateful to have a copy. thank you. christy g. turner ii regents’ professor emeritus of anthropology college of human evolution and culture change arizona state university tempe, az 85287-2402 e-mail: chrstygturner@aol.com gantt et al. 1998.1 pg1.jpg pg2.jpg sperber 2004.1 1 the genetics of odontogenesis: implications in dental anthropology and palæo-odontology geoffrey h. sperber* department of dentistry, university of alberta, edmonton, alberta, canada *address for correspondence: g. h. sperber, department of dentistry, faculty of medicine and dentistry, university of alberta, edmonton, alberta t6g 2n8, canada e-mail: gsperber@ualberta.ca editor’s note: the editor solicited professor sperber to write this review article for dental anthropology. evolutionary genetics “the crown of the human tooth even in its minute details represents little that is fortuitous. it is the resultant of inherited ancestral conditions, modifying further by evolution and involution.” a. hrdlička, 1924 dental characters predominate in the identification of most species and genera, both of fossil and extant varieties. in this respect, teeth are unique among organs in enabling direct comparisons to be made between fresh specimens formed a few months previously and fossils excavated from sediments formed millions of years ago. teeth depict their genetically inherited patterns, and thus their evolutionary history, more accurately than all other organs. this precision of genetic expression is due to their highly protected developmental environment, ensconced as they are in their submerged dental follicles until their full morphological maturity, before emerging into the potentially damaging environment. by casting their primeval and delicate genotypic templates into the enduringly fossilized form of highly mineralized phenotypic morphology, teeth are the ultimate and amongst the most perfect extrinsic abstract palaeoanthropology and forensic odontology rely significantly upon detailed dental morphology that is ultimately the phenotypic expression of the underlying genotype and developmental phenomena. odontogenesis is the consequence of a complex series of molecular interactions controlled by epigenetic signals acting on embryonic epithelialmesenchymal tissues of ectodermal, neural crest and mesodermal origin. of the estimated 24,847 genes of the human genome (pearson, 2003) some 200 or more genes have been directly or indirectly involved in tooth development (http://bite-it.helsinki.fi). the loci of these genes on the 22 pairs of autosomes and the pair of sex chromosomes are being identified by their mutations that give rise to phenotypic dental abnormalities. the sequential cascades of stages from initiation through the bud, cap, bell, mineralization, root formation and eruption of teeth are all under genetic control but subject to environmental influences. identification of specific genes with clinical phenotypes provides invaluable clues to familial, racial and evolutionary affinities, all of jurisprudential, heredity and evolutionary significance to odontologists. combining the genetics of odontogenesis with forensic evidence and palaeoanthropological fossil data provides an unparalled source of information on heredity, environmental and evolutionary events through teeth, the most durable of all biological structures after death. it is paradoxical that teeth are most susceptible to decay during life, but postmortem are the last structures to disintegrate. teeth truly tell tales of the living and the dead. dental anthropology 2004;17(1):1-7. expressors of the intrinsic units of evolutionary change, the mutations of genes. the intricate morphology of the crowns of human teeth reflects both a long and complex phylogenetic archival record and a brief but extraordinarily elaborate ontogenetic formulation. this combination of long hereditary and short embryologic developments lies within the genes determining tooth shapes. the influence of phylogenetic factors upon the ontogeny of teeth is responsible for many of the factors peculiar to odontogenesis, making the study of dental development at the forefront of “evo-devo” exploration. the divergence of taxa heretofore based exclusively on fossil remnants may now be pursued by studying the selective action of genes during developmental processes (mccollum and sharpe, 2001). new pathways of palaeoanthropological research are now being revealed by the genetic revolution. the genetics underlying phenotypic dental characteristics that are directly observable has enabled rates and degrees of gene flow to be calculated and genetic drift to be estimated in divergent populations. mutations may be traced in this manner, and the 2 3 selective advantages of particular dental conformations might account for dental micro-evolution. the development of cusps, ridges and fissures that enhance the predatory and masticatory capability of teeth are evolutionary advancements that correlate with different diets and environmental niches. developmental genetics the complexity of contributions of over 200 genes to odontogenesis makes the elucidation of each genes’ individual responsibility for each stage of development a daunting task. most of these genes encode signals as well as their receptors, both in the cytoplasm and in transcription factors regulating gene expression in the nucleus (thesleff, 2000). it is the mutation or deletion of these genes, by phenotypically expressing dental malformations or anodontia, or by experimental “knock outs” of specific genes, that some of the responsibilities of each gene is revealed. the intricacies of rna editing, complex regulatory networks and criss-crossing molecular pathways makes meaningless the exact identification of genetic units. moreover, the overlapping and redundancy of genetic expression patterns during development make the unravelling of the skein of influences particularly difficult. teeth initially developed in primitive fishes from the adaption of placoid scales overlying their jaws to form dermal denticles (smith and johanson, 2003). with the pending identification of genes responsible for the development of ectodermally-derived hard tissues, the revelation of the evolution of teeth becomes a possibility in the newly emerging discipline of phylogenomics (eisen and fraser, 2003). the synteny of conserved genes across species will account for the identification of “dental” genes in human odontogenesis having initially evolved in piscine species. this phylogenetic dermal origin of teeth is reflected in the embryonic development of human teeth, which although they develop submerged beneath the oral gingival epithelium, originate in part from ectodermal tissue. teeth are derived from two of the primary germ layers, ectoderm and mesoderm, with a neural crest contribution. the enamel of teeth is derived from oral ectoderm, and neural crest mesenchyme provides material for the dentine, pulp and cementum. the periodontium is of both neural crest and mesodermal origin. the morphogenesis of the maxillary and mandibular teeth is under the control of two different genetic programs, accounting for variation between upper and lower dentitions that provide for taxonomic distinctions. combinations of different sized teeth within individuals reflect mosaic evolutionary derivations (mccollum and sharpe, 2001). an early signally event in tooth development at 6 weeks postconception is the induction of odontogenic mesenchyme by bone morphogenetic proteins (bmps) and fibroblast growth factors (fgfs) from the oral ectoderm. these initial odontogenic epithelial signals induce in the mesenchyme the expression of reciprocal signal molecules to the epithelium that results in the formation of the dental placode. the placodal signals, expressed as sonic hedgehog (shh), wingless (wnt) and tumor necrosis factor (tnf) molecules regulate the budding of the epithelium and condensation of the mesenchyme, effectively creating tooth buds (thesleff and mikkola, 2002). the number of tooth buds developing in each jaw is genetically determined, with an initial identicality that is later altered by their location. the differential odontogenic patterning creating a variety of tooth shapes (incisors, canines, molars) is organized by a homeodomain code of transcription factors expressed in restricted regions during development (sharpe, 1995; tucker and sharpe, 1999; cobourne and sharpe, 2003). these factors include the msx genes, dlx family members, pax 9, lhx genes and barx1 (francis-west et al., 1998, maas and bei, 1997; jung et al., 2003). the precise role of many of these signaling molecules during early budding is still under investigation. barx1 expression is restricted to the presumptive proximal (posterior) region of the first pharyngeal arch, influencing the tooth buds to a molarization pattern (tucker et al., 1999). the lim homeodomain protein islet 1 (isl1) that is exclusively expressed in the presumptive incisor epithelium coincides with expression of bmp4 that induces msx1 expression in the underlying mesenchyme (mitsiadis et al., 2003). the mesenchyme of the presumptive distal (anterior) region of the first arch expresses both msx1 and alx3 homeobox genes that determine incisiform shapes to the developing tooth buds (ten berge et al., 1993). the region of overlap between msx and dlx genes codes for canines and premolars (fig. 1). the transcription factor runx 2 and the signal fgf 3 regulate epithelial morphogenesis from bud to cap stages. a primary enamel knot forms at the tip of the tooth bud, consequent to bmp 4 induction. the exit of enamel knot cells marks the onset of development of the tooth crown to form a cap-like structure that surrounds the underlying mesenchyme, referred to as the dental papilla. a shh signal from the enamel knot is required for the growth of the epithelial cervical loops flanking the enamel knots and encompassing the dental papilla (thesleff, 2003). primary enamel knots initiate secondary enamel knots, thereby regulating the patterning of the tooth crown.. the arrangements and intercuspal dimensions of molar teeth are determined by the enamel knots (townsend et al., 2003). enamel knots are transient signaling centers that disappear by apoptosis (vaahtokari et al., 1996). the consequent epithelial sheet folds in an exact sequence to produce undulating peaks and valleys, adumbrating cusps and fissures in the future crowns. this folding must involve g. h. sperber 2 3anthropalaeo-odontological genetics f ig 1 . s ch em at ic d ep ic ti on o f fa ct or s op er at in g in o d on to ge n es is . 4 5 differential mitotic activity by inhibition and activation determined by gene expression patterns to produce different tooth shapes (salazar-ciudad and jernvall, 2002). enamel formation the secretion of the proteins unique to the enamel matrix, ameloblastin, amelogenin, enamelin and tuftelin by ameloblasts precedes the most intense mineralization of any tissue in the body (dong et al., 2000). the ameloblast, the heralder of the hardest of human tissues, lays down a matrix that by mineralization becomes petrified, providing fossilized, immortal remains within the living jaws. enamelin, the largest enamel extracellular matrix protein is a uniquely ameloblastic secretion, and is involved in the nucleation of apatite crystals (gibson, 1999). enamelin persists in mature enamel, whereas ameloblastin and amelogenin occur only temporarily in immature enamel (robinson et al., 1989; deutsch 1989). moreover, there is an evolutionary sequence to the appearance of these proteins, with enamelins appearing earlier in phylogenetic history than amelogenins, and differing in their distribution among species (herold et al., 1989), emphasizing the relationship of molecular biology to phylogeny. the tuftelin gene (tuft1) has been mapped to chromosome 1q (deutsch et al., 1994). the gene for the ameloblastin protein, ambn, is located on chromosome 4q, and is a single copy gene containing 13 exons (toyosawa et al., 2000). enamel thickness the speed and direction of migration of the ameloblasts in laying down enamel matrix, again under genetic control, determines the ultimate thickness of the enamel cap of the dental crown. the limited life of postmitotic ameloblasts, determined by their programmed early cell death, varies in different locations on the dental crown surface. this accounts for the varying ultimate thickness of enamel, from minimal along the cervical margins and in fissure depth, to maximal over the cusp peaks. this variation of enamel thickness not only reflects the longevity of ameloblasts, but also the speed of their migration. this combination of ameloblastic activities varies phylogenetically, accounting for the different maximal thicknesses of enamel found among hominoids and hominins (beynon and wood, 1986; grine and martin, 1989). the thin enamel of the gorilla, chimpanzee and orangutan contrasts strongly with the thick enamel of homo sapiens and the australopithecines. the folivorous diet of the great apes, relatively free of abrasive grit, is not as wearing on dental enamel as the gritty omnivorous diet of hominins. enamel thickness is correlated with longevity, as hominins long outlive pongids. the periodicity of incremental deposition of the enamel matrix leading to the striae of retzius, allows for age assessment at the time of death or exfoliation of extant and fossil teeth (boyde 1963; fitzgerald 1996; shellis 1998). during the year or two that a tooth develops and erupts, it accumulates isotopes of carbon and oxygen. variations in the ratios of c13 to c12 and o18 to o16 provide evidence of the ambient diets of fossilized teeth. this isotopic evidence, in turn, may provide information on the provenance of recovered remains, even to the extent of tracing habitats and migrations during a lifetime, as revealed by the peregrinations of the alpine iceman (müller et al., 2003). ameloblasts are extremely sensitive to metabolic, dietary and drug influences during enamel matrix deposition. the mechanisms of mineralized tissue deposition during amelogenesis provide a kymographic record of the state of metabolism and nutrition of the individual that is permanently entombed in the hard dental tissues. accordingly, illnesses and drug therapy during amelogenesis may be recorded as hypoplasias, hypomineralization or distinctive marks in matured enamel. such examples as tetracyline staining or the neonatal line reflecting the change from intrauterine to extrauterine nutrition are ineradicably imprinted on enamel. incremental enamel apposition produces surface perikymata that allows determination of variations in their spacing, reflecting chronological deposition rates (guatelli-steinberg 2003). these rates have been determined to differ between apes, hominids and hominins (dean et al., 2001). amelogenesis can provide insights into cladistic relationships of the different species of hominoids, and their different rates of body maturation (beynon and dean, 1998; smith, martin and leakey, 2003). the rapid growth of the neanderthals has been based upon incremental dental data (rozzi and de castro, 2004). the direct association of the sex chromosome genes that influences enamel development with the thickness of this tissue and with taurodontism indicates the ontogenetic link of dental morphology with evolutionary changes and phylogenetic influences. the aneuploid presence of extra sex chromosomes (47, xxx females, 47, xyy males) manifest thicker than normal enamel (alvesalo et al., 1985; alvesalo et al. 1987). taurodontism, a trait carrying strong neandertaloid associations is linked with aberrant sex-chromosome syndromes (gage, 1978; varrela et al., 1990). odontogenesis each tooth germ consists of an enamel organ and a dental papilla surrounded by a dental follicle or sac. the dental papilla, of neural crest origin, and dental follicle of mesodermal origin, are the anlagen of the dental pulp and part of the periodontal apparatus g. h. sperber 4 5 respectively. each enamel organ during its development changes from its initial small bud shape, enlarging by rapid mitosis of the basal cells into a cap shape, and later cupping into a large bell shape, by which shapes the three stages of enamel organ development are designated. concomitant with these morphological alterations, histodifferentiation occurs within the enamel organ. its external layer forms the outer enamel epithelium, a layer of cuboidal cells subjacent to the developing follicle. the stellate reticulum, composed of stellate cells set in a fluid matrix, constitutes the central bulk of the early enamel organ. the indented inner layer, lining the dental papilla, forms the inner enamel epithelium, part of which differentiates into the transient secretory columnar ameloblasts that form enamel. lining a portion of the stellate reticular surface of the inner enamel epithelium is a squamous cellular condensation, the stratum intermedium, that probably assists the ameloblasts in forming enamel. the inner and outer enamel epithelia form the cervical loop, elongating into hertwig’s epithelial root sheath, that, by enclosing more and more of the dental papilla, outlines the root(s) of the tooth. the number of roots of a tooth is determined by the subdivision, or lack thereof, of the root sheath into one, two or three compartments. the regulation of root development is dependent upon genes encoding nuclear factor i (nfi) transcription-replication proteins (steele-perkins et al., 2003). aneuploid variation of the x chromosome’s “dental genes” appears to influence the mitotic activity of odontoblasts to produce taurodontic teeth (varrela and alvesalo, 1988; varrela et al., 1990). the inner enamel epithelium interacts with the ectomesenchymal cells of the dental papilla, whose peripheral cells differentiate into odontoblasts. the formation of dentine by the odontoblasts precedes, and is necessary for, the induction of premeloblasts into ameloblasts to produce enamel. the inner enamel epithelium of the root sheath induces odontoblast differentiation but, lacking a stratum intermedium, fails to differentiate itself into enamel-forming ameloblasts, accounting for the absence of enamel from the roots. cementum forms on dentine adjacent to the sites of disintegration of the outer enamel epithelium of the root sheath. the fragmentation of the root sheath, due to programmed cell death (apoptosis) leaves clusters of cells, the epithelial rests of malassez, in the periodontal ligament. these rests are the source of potential periodontal cysts. the fibers in the initial cementum derive solely from fibers of the pre-existing dental follicle that form the first principal fibers of the periodontal ligament. the ameloblasts of the inner enamel epithelium and the adjacent odontoblasts together form a bilaminar membrane, which spreads by mitosis under genetic control and varies among the tooth germs in different areas as previously described. the ameloblasts secrete a protein matrix of amelogenins and enamelins that later mineralize as enamel rods or prisms as they retreat from the membrane. concomitantly, the odontoblasts secrete the collagen matrix of predentine, which later calcifies to dentine. dentine deposition is a continuous process throughout life. the dental papilla differentiates into the dental pulp, the peripheral cells into odontoblasts, and the remaining cells into fibroblasts. enamel formation is restricted to the preeruptive phase of odontogenesis and ends with the deposition of an organic layer, the enamel cuticle. the enamel organ collapses after deposition of this cuticle. the inner and outer enamel epithelia together with the remains of the stratum intermedium form the reduced enamel epithelium, which later fuses with the overlying oral mucous membrane to initiate the pathway for eruption. the tissues of the dental pulp, the only unmineralized dental tissues, are confined within the enclosed pulp chamber, protected by the surrounding mineralized tissues. this protection provides the possibility of preservation of pulp tissues beyond death, enabling both forensic and palaeo-odontological investigations to be performed on tissues that may reveal dna formulations (komuro et al., 1998). moreover, dental pulp tissues may contain stem cells of highly proliferative clonogenic capability, with the potentiality to differentiate into a variety of cell types (gronthos et al., 2002; miura et al., 2003). the possibility of clinical application of this stem cell source for therapies and tissue engineering remains to be explored, but the cloning of a whole individual from a dental pulp cell is still a fictional absurdity. nonetheless, dental pulp cells have been shown to provide neurotrophic support for dopaminergic neurons as a treatment modality for parkinson’s disease (nosrat et al., 2004). moreover, the cultivation of stem cells to produce teeth has been successfully achieved in experiments with mice, and portends the future therapeutic replacement of teeth in humans (ohazama et al., 2004). conclusions odontogenesis and phylogenesis are inextric-ably interlinked through genetics in a combination that accounts for the complex functional morphology of the total dentition and its individual units, the teeth. the dental components-the crowns and their cusps, the roots, the pulp chambers and their tissues and the 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evolution. bioessays 23:481-493. miletich i, sharpe pt. 2003. normal and abnormal dental development. hum mol genet 12:r69-r73. mitsiadis ta, angeli i, james c, lendahl u, sharpe pt. 2003. role of islet1 in the patterning of murine dentition. development 130:4451-4460. miura m, gronthos s, zhao m, lu b, fisher lw, robey pg, shi s. 2003. shed: stem cells from human exfoliated deciduous teeth. proc nat acad sci 100: 5807-5812. müller w, fricke h, halliday an, mcculloch wj-a. 2003. origin and migration of the alpine iceman. science 302:862-866. nosrat iv, smith ca, mullally p, olson l, nosrat ca. 2004. dental pulp cells provide neurotrophic support for dopaminergic neurons and differentiate into neurons in vitro: implications for tissue engineering and repair in the nervous system. eur j neurosci 19:2388-2398. ohazama a, modino sac, miletich i, sharpe pt. 2004. stem cell-based tissue engineering of murine teeth. j dent res [in press]. pearson h. 2003. geneticists play the numbers game in vain. nature 423:576. robinson c, weatherall ja, hobling hj. 1983. g. h. sperber 6 7anthropalaeo-odontological genetics formation and mineralization of dental enamel. trends biochem sc 8:284-287. rozzi fvr, de castro jmb. 2004. surprisingly rapid growth in neanderthals. nature 428:936-938. salazar-ciudad i, jernvall j. 2002. a gene network model accounting for development and evolution of mammalian teeth. proc nat acad sci usa 99: 8116-8120. sharpe pt. 1995. homeobox genes and orofacial development. conn tiss res 1995; 32:17-25. shellis rp. 1998. utilization of periodic markings in enamel to obtain information on tooth growth. j hum evol 35:387-400. smith mm, johanson z. 2003. separate evolutionary origins of teeth from evidence in fossil jawed vertebrates. science 299:1235-1236. smith tm, martin lb, leakey gm. 2003. enamel thickness, microstructure and development in afropithecus turkanensis. j hum evol 44:283-306. steele-perkins g, butz kg, lyons ge, zeichner-david m, kim h-j, cho m-i, richard m. 2003. essential role for nfi-c/ctf transcription-replication factor in tooth root development. mol cell biol 23:10751084. ten berge d, brouwer a, el bahi s, guenet jl, robert b, meijlink f. 1998. mouse alx3: an aristaless-like homeobox gene expressed during embryogenesis in ectomesenchyme and lateral plate mesoderm. dev biol 199:11-25. thesleff i. 2000. genetic basis of tooth development and dental defects. acta odont scand 58:191-194. thesleff i. 2003. epithelial-mesenchymal signalling regulating tooth morphogenesis. j cell sci 116:16471648. thesleff i, mikkola m. 2002. the role of growth factors in tooth development. int rev cytol 217:93-134. townsend g, richards l, hughes t. 2003. molar intercuspal dimensions. j dent res 82:350-355. townsend gc, alvesalo l. 1985. tooth size in 47 x 44 males: evidence for a direct effect of the y chromosome on growth. aust dent j 30:268-272. toyosawa s, fujiwara t, oeshima t, shintani t, sato a, ogawa y, sobue s, ijuhin n 2000. cloning and characterization of the human ameloblastin gene. gene 256:1-11. tucker as, matthews kl, sharpe pt. 1998. transformation of tooth type induced by inhibition of bmp signaling. science 282:1136-1138. tucker as, sharpe pt. 1999. molecular genetics of tooth morphogenesis and patterning: the right shape in the right place. j dent res 78:826-834. vaahtokari a, åberg t, thesleff i. 1996. apoptosis in the developing tooth: association with an embryonic signaling center and suppression by egf and tgf4. development 122:121-129. varrela j, alvesalo l. 1988. taurodontism in 47,xxy males: an effect of the extra x chromosome on root development. j dent res 67:501-502. varrela j, alvesalo l, mayhall j. 1990. taurodontism in 45,x females. j dent res 69:494-495. website http://bite-it.helsinki.fi silva and silva 2007.3 1� double teeth, that is, two conjoined teeth, are considered a clinical manifestation of two developmental anomalies taking place during the bud stage of tooth formation: gemination and fusion. gemination is the attempt of division of a single tooth germ whereas fusion, the joining together of two dental germs (alpoz et al., 2003; gurri and balam, 2006; tomizawa et al., 2002). there is a general agreement that it is sometimes difficult to separate these two events, due to the possibility of synchronous anomalies (neves et al., 2002). thus, some authors argue that these two developmental events should not be separated while others propose that some diagnostic criteria be used, such as counting the teeth in the affected arch (gurri and balam, 2006) and radiological analysis (neves et al., 2002; santos et al., 2003; schuurs and van loveren, 2002). fusion, for instant, will diminish the number of teeth, whereas gemination will not (gurri and balam, 2006; neves et al., 2002; tomizawa et al., 2002). according to the clinical literature, the most commonly involved double teeth are central and lateral incisors, followed by lateral incisors and canines (gurri and galam, 2006; neves et al., 2002; santos et al., 2003; schuurs and van loveren, 2000; tomizawa et al., 2002). double teeth are more common in the primary dentition, ranging from 0.4% to 0.9% in the mandible and are predominantly unilateral (schuurs and van loveren, 2002). the majority of reports conclude that there is no sex preference for this anomaly (santos et al., 2003; schuurs and van loveren, 2000). a family tendency has been suggested (santos et al. 2003). rarely, fusion in three elements is reported (erdem et al., 2001; mochizuki et al., 1999). this paper reports an archeological case of double teeth, probably due to a unilateral fusion of two lower deciduous teeth, a lateral incisor and a canine. unilateral fusion of two primary mandibular teeth: report of a portuguese archeological case ana maria silva* and ana leonor silva centro de investigação em antropologia, department of anthropology, university of coimbra, 3000 – 056 coimbra – portugal *correspondence to: ana maria silva, centro de investigação em antropologia, department of anthropology, university of coimbra, 3000 – 056 coimbra – portugal e-mail: amgsilva@antrop.uc.pt abstract: this paper describes a unilateral fusion of two mandibular teeth in an infant skeleton recovered from the late roman cemetery of miroiço (sintra, portugal). morphological and radiographic data were used for the analysis and interpretation of this dental anomaly. a brief review of the literature of present day primary dental fusion is presented. this report shows that primary dental fusion was present in portuguese past populations, representing a contribution to the history of dental anomalies. dental anthropology 2007;20:16-18. materials and methods during osteological analysis of the human remains (minimal number of 64 individuals) recovered from the late roman cemetery of miroiço (sintra, portugal) (macedo, 2002; silva, 2003), a case of double primary mandibular teeth was recognized in the infant skeleton labelled 30.2. although not firmly dated, it appears that the necropolis may have been in use during the 2nd – 4th centuries ad (cardoso, 2001). age at death of this infant skeleton was estimated with the dental remains. the formation of each tooth crown was assessed using the standards of smith (1991). maturation of the recovered teeth is consistent with an age of death of 3 to 4 years old. there is consistency of this age at death assessed throughout the recovered dentition. case report from the lower primary dentition of infant skeleton labelled 30.2 (fig. 1a), only the two central incisors and the crowns of the left first molar were missing. in the position of teeth 72 and 73 (fig. 1b), a double teeth was observed. since no anomaly was observed in the right mandibular quadrant, this represents a unilateral event. from the maxilla, only the right arch was recovered with teeth 51 to 55 and the crowns of teeth 11, 12, 13, 14 and 15, visible through a postmortem broken area of the bone. teeth 65 and crown of teeth 26 were recovered as loose teeth. 17 the double teeth displays a bifid crown with a well defined buccal groove that extends from the incisal edge to the apex of the root (fig. 1b). in lingual view, the groove is readily visible between the incisal edge to initial cervical two-third of the crown, being very tenuous along the rest of the tooth. radiographic examination revealed that the double tooth has two separate pulp chambers and root canals (figs. 2 and 3). no other bony or dental anomaly, such as supernumerary teeth, was detected in the skeletal remains from this infant. discussion this paper describes a case of double teeth detected in the primary dentition of a late roman infant skeleton that seems to result from the fusion of teeth 72 and 73. this diagnosis is based on the tooth count and on radiological examination. although clinical cases are described in the literature (aguiló et al., 1999; alpoz et al, 2003; gurri and balam, 2006; neves et al., 2002; schuurs and van loveren, 2000; tomizawa et al. 2002), this anomaly seems to be rare in past populations. to our knowledge, this is the first report of an archeological case, although another unpublished case was recovered from peru, involving lower first and second deciduous incisors (oral communication from prof. simon hillson). the fusion is incomplete and took place late in odontogenesis resulting in a readily discernible fused crown and two roots. radiographical examination (figs. 2 and 3) revealed two separate pulp chambers and root canals. although many clinical reports found association of fusion of primary teeth with succedaneous ones (e.g., reddy and munshi, 1999), no other abnormality was detected in the present case. clinical problems related to double teeth include caries along the grooves dividing each crown, esthetics, and malocclusion (neves et al., 2002; santos et al., 2003). in the present archeological case, only the former issue could be analyzed. no cariogenic lesion was detected in the double teeth or any other tooth recovered from the dentition of this late roman child. regarding the etiology of this dental anomaly, neves et al. (2002) proposed genetic inheritance or physical pressure leading to the union of teeth. in a recent review, gurri and balam (2006) concluded that fusion is probably associated with a mandibular extension of tooth reduction and that it is under different genetic control of gemination. gemination, in contrast, could be link to a maxillary extension of tooth enlargement and increment in number. unfortunately, no inferences are possible in the present archeological case because in the human remains unearthed from this necropolis no other dental anomalies were detected. in sum, in recent years interdisciplinary studies in areas such as paleopathology, odontology and radiology (chimenos-küstner et al., 2006; jordana et al., 2004), as in the present study, are contributing to the documention and interpretation of past (silva, 2002) and present dental anomalies (aguiló et al., 1999; alpoz et al., 2003; gurri and balam, 2006; neves et al., 2002; schuurs and van loveren, 2000; tomizawa et al., 2002). a b fig. 1. dental remains recovered from infant skeleton 30.2 from the late roman cemetery of miroiço (portugal). (a) view of the anterior portion of the mandible; (b) detail of the double teeth from the mandibular left quadrant. fusion of mandibular primary teeth 18 acknowledgments we would like to thank maria teresa ferreira and eugénia cunha (departamento de antropologia da universidade de coimbra); ana corte real (faculdade de medicina dentária, university of coimbra); simon hillson (institute of archaeology, university college london), miguel costa (dentist), and câmara municipal de sintra. literature cited aguiló l, gamdia jl, cibrian r, catala m. 1999. primary double teeth. a retrospective clinical study of their morphological characteristics and associated anomalies. int j pediatric dent 9:175-183. alpoz ar, munanoglu d, oncag o. 2003. mandibular bilateral fusion in primary dentition: case report. j dent child 70:74-76. cardoso g. 2001. a necrópole de miroiço (manique – cascais). unpublished field report. chimenos-küstner e, agustí-farjas b, probable keratocyst in a mandible from the late roman era. dentomaxillofacial radiol 35:60-64. erdem g, uzamis m, ölmez s, sargon m. primary incisor triplication defect. asdc j dent child 68:322-325. gurri f, balam g. 2006. inheritance of bilateral fusion of the lower central and lateral incisors: a pedigree of a maya family from yucatan, mexico. dental anthropology 19:29-34. jordana x, garcía c, palacios m, chimenos e, malgosa a. 2004. bifid mandibular condyle: archaeological case report of a rare anomaly. dentomaxillofacial radiol 33:278-281. macedo m. 2002. villa romana de miroiço… uma leitura. estudo paleobiológico de uma amostra de esqueletos de manique – cascais. tese de licenciatura. coimbra, departamento de antropologia da f.c.t.u.c.. unpublished report. mochizuki k, yonezu t, yakushiji m, machida y. 1999. the fusion of three primary incisors: report of case. asdc j dent child 66:421-425 neves aa, neves mla, farinhas ja. 2002. bilateral connation of permanent mandibular incisors: a case report. int j paediatric dent 12:61-65. reddy nn, munshi ak. 1999. fusion of primary incisors–a report of six cases. j indian soc pedod prev dent 17:55-60. santos lm, forte fds, rocha mjc. 2003. pulp therapy in a maxillary fused primary central incisor—report of a case. int j paediatric dent 13:274-278. schuurs ahb, van loveren c. anomalies. 2000. double teeth: review of the literature. asdc j dent child 67:313-325. silva am. 2002. antropologia funerária e paleobiologia de populações portuguesas do neolítico final/calcolítico. tese de doutoramento em antropologia biológica, coimbra, departamento de antropologia da f.c.u.t.u. unpublished ph.d. thesis. silva, al. 2003. registo de um quotidiano….na villa romana de miroiço. análise paleobiológica de uma amostra de esqueletos exumados da necrópole de miroiço. tese de licenciatura. coimbra, departamento de antropologia da f.c.t.u.c. unpublished report. smith bh. 1991. standards of human tooth formation and dental age assessment. in: kelley m, larsen cs, editors. advances in dental anthropology. new-york: wiley-liss, 1991, p 143-168. tomizawa m, shimizu a, hayashi s, noda t. 2002. bilateral maxillary fused primary incisors accompanied by succedaneous supernumerary teeth: report of a case. int j paediatric dent 12:223-227. fig. 2. posterio-anterior radiograph of the mandible of infant skeleton 30.2 from miroiço (portugal). note the double teeth in positions 72 and 73. fig. 3. labiolingual radiograph of the double teeth from infant skeleton 30.2 from miroiço (portugal). a.m. silva and a.l. silva harris 1997.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg 3 dental anthropology 2019 │ volume 32 │ issue 01 case study: expression of two near absent dental traits, lingual cuspule and paraconid, on one archaic period modern human from the ohio valley erin c. blankenship-sefczek * the ohio state university, usa keywords: dental variation, dental evolution, rare trait over the course of human evolution there is a simplification in the expression of tooth traits (i.e. a reduction in cusp number, and occlusal ridges; bailey and hublin, 2013); however, there still exists considerable variation in the expression of dental morphology in world populations (turner et al., 1991; scott and turner, 1997; hanihara, 2008; scott et al., 2016; irish, 2016). placement of tooth cusps, both principal and accessory, can be used to discuss morphological variation. generally, accessory cusps are initiated after the principal cusps have formed (kraus and jordan, 1965; hillson 1996) making their expression more variable and less frequent than principal cusps. while many mandibular paramolar structures, such as the mandibular molar pit -tubercle (mmtp; weets, 2009) and protostylid (dahlberg, 1950), have been identified and described in several populations, there are several traits that are less common. for example, odontomes on premolars, the mesial canine ridge (scott and turner, 1997), and the labial talon cusp on incisors (stojanowski and johnson, 2011) are much less common traits within a given population. traits that are found in 4-7% of a population are considered “rare”; “very rare” traits are found in 1 3% of a population, and “near absent” when they are found in less than 1% of a population (scott and turner 1997: 191, 193). assessing patterns of dental trait expressions are useful to understand biological variation, migration of modern human populations around the world (scott and turner, 1997; hanihara, 2013; scott et al., 2018), and evolutionary changes within and between hominin taxa (bailey and hublin, 2013; martinon-torres et al., 2013; guatelli-steinberg 2016). the goals of this paper are to 1) describe two rare lower molar traits, the lingual cuspule (irish, 1991) and the paraconid, and 2) contextualize them in modern human variation. only one other study has identified the lingual cuspule, which was observed on a single individual (irish, 1991). the paraconid is a principle cusp which has been identified in early primate ancestors, but appears to have been lost, with the exception of tarsiers, before the emergence of hominins (gregory, 1922; ankel-simons, 2007; fleagle, 2013). to date, no studies have reported this cusp in modern humans. both the lingual cuspule and the paraconid were observed on mandibular third molars of a single individual from the archaic period (2500-500 bc) in the ohio valley. neither of these dental anomalies has been extensively documented in modern humans, and both may be considered near absent in world populations. it is possible that these molar cusps are simply overabstract dental anomalies in modern humans are used to discuss biological variation and evolutionary changes. presented here are the lingual cuspule and paraconid; two traits considered near absent (occurring <1%) in world populations. the only other example of a lingual cuspule comes from an african population. the paraconid was thought to have been lost in primate evolution starting in the oligocene (34-23 mya). both traits were found on the lower third molars of a male individual from the late archaic (2500-500 bc) site of shick in handcock county, ohio. here the lingual cuspule is present unilaterally on the right third molar, whereas the other reported case shows the trait being expressed bilaterally on the first molars. therefore, the lingual cuspule can be found on molars across the row. additionally, each example exhibits a fully developed cuspule with a free apex. these data indicate the lingual cuspule could be incorporated into studies of biodistance and morphological variation. contextualizing the paraconid is more challenging given that the only reported examples of this trait in extant primates come from the tarsier. the expression of a paraconid in modern humans could suggest secondary evolution of this trait. further reporting of both the lingual cuspule and paraconid are necessary to better understand these traits and discuss their importance in modern human variation. *correspondence to: erin c. blankenship-sefczek department of anthropology the ohio state university blankenship-sefczek.1@osu.edu 4 dental anthropology 2019 │ volume 32 │ issue 01 looked, in which case studies should highlight them, or that they are misinterpreted, which would indicate new methods should be used to amend recording procedures. materials and methods this study was conducted on human skeletal remains from the archaic period in the ohio valley. the individual presented in this paper was found at the shick site located in mount cory, handcock county, ohio occupied between 2500-500 bc. the skeletal collections are housed at the ohio history connection in columbus, ohio. the shick site settlements during the archaic period were considered “sizable” compared to earlier periods, and were occupied on a seasonal basis (sciulli and oberly 2002). late archaic communities practiced a hunting and gathering subsistence (sciulli and oberly 2002). fourty-eight individuals from the late archaic period were examined. tooth traits for all individuals were recorded using the arizona state university dental anthropology system (asudas; turner et al. 1991). reference manuals, recent publications (scott and turner, 1997; weets, 2009; marado and silva, 2016; scott et al., 2016; scott and irish, 2017), and consultation with joel irish were used to identify these traits as neither the lingual cuspule nor paraconid are included in the asudas. based on information from available sources, the descriptions presented below were used to identify the two cusps. the lingual cuspule is described as a “triangularshaped structure” located on the disto-lingual enamel surface, not associated with the metaconulid (cusp 7), and similar in form, though not in location, to the protostylid (found on the buccal surface; irish, 1991:2). originating at the cemento-enamel junction just distal on the metaconid, the lingual cuspule is not an occlusal trait (irish, 1991), but a rather is a peripheral accessory cusp. taking up the mesial portion of the trigonid of lower molars, the paraconid is described as a principal cusp located most anterior and mesiolingually to the other lower molar cusps (gregory, 1922; ankel-simons, 2007; fleagle, 2013). the paraconid is noted as being an archaic primate feature that reduces in size and disappears altogether by the oligocene (gregory, 1922; simons, 1989; ankel-simons, 2007; fleagle, 2013). the tarsier is the only reported example of a modern primate to have retained the paraconid (swindler, 2002; ankel-simons, 2007). results of the 48 individuals observed from the late archaic sample, only one was found to have either a lingual cuspule or a paraconid (a4489-6). the lingual cuspule was observed on this individual’s mandibular right third molar and the anterior cusp (paraconid) was expressed bilaterally. while the lingual cuspule and the paraconid are the two cusps of interest in this paper, individuals in the late archaic sample exhibited a variety of other lower molar traits including low-grade expressions of the protostylid (n=20), fully developed cusp 6 (n=11), large cusp 7 (n=1), deep anterior fovea (n=8), and defined deflecting wrinkle (n=4). in addition to the lingual cuspule and the paraconid, the individual presented here also exhibited a low-grade expression of the protostylid (pit in the buccal groove; turner et al., 1991) on all lower molars as well as a bifurcated hypoconulid on the lower right third molar. the upper molars of this individual exhibit a reduction in size of the hypocone from the first to third molars on both sides. lingual cuspule the lower right third molar of this individual exhibits a large, fully developed cuspule located mesially on the lingual surface of both the paraconid and metaconid of a right third molar (figure 1, arrow 1). the lingual cuspule is nearly equal in size to the protoconid, metaconid, and paraconid. the tooth appears to have been rotated buccally such that the paraconid is oriented toward the buccal aspect of the mandible, rather than to the distal portion of m2; the orientation brings the lingual cuspule into contact with the hypoconulid of m2. figure 1. lower right third molar from burial a4489-6 (archaic period; mt. cory ohio, handcock county) with a fully developed lingual cuspule (arrow 1) and paraconid (arrow 2). 5 dental anthropology 2019 │ volume 32 │ issue 01 paraconid on the right and left third molar, this individual possesses a cusp in the location where, by definition (gregory, 1922; ankel-simons, 2007; fleagle, 2013) the paraconid develops. in both expressions, a fully developed mesial cusp with a free apex is present (figure 1, arrow 2 and figure 2). the cusp appears to originate at the cemento-enamel junction between the protoconid and metaconid. the root exhibits a seamless transition with the enamel suggesting the cusp was formed along with other principal cusps during the initial down-folding of the enamel epithelium (jernvall and thesleff, 2000) and is not a peripheral accessory cusp. the cusp is equal in size to the protoconid and metaconid. discussion based on the available literature, it appears that the lingual cuspule and the paraconid are near absent traits in modern human populations. while more information is needed about both traits to complete a more in depth discussion on how they might inform on studies of migration, or biodistance, it is possible to demonstrate their eventual usefulness in these applications. scott (2008) identifies a set of criteria, or principles, to use when including a new trait into studies of biodistance. these criteria begin with 1) the presence of a distinct trait, 2) a consistent expression of the trait within the same tooth type, and 3) examination of multiple diverse populations for presence of the trait. after these steps have been satisfied, there can be a more in-depth analysis of the trait wherein a scoring system is developed (scott, 2008). both the lingual cuspule and the paraconid satisfy the first criteria of being distinct traits. with the inclusion of other sources, a discussion of criterion two and three is possible for the lingual cuspule, and will be undertaken below. given the lack of paraconid examples in modern humans, contextualizing this trait within scott’s (2008) criterion cannot be done here. the paraconid can, however, be discussed in an evolutionary context. lingual cuspule scott’s (2008) second criteria requires that the trait in question be consistently expressed within the same tooth type. regarding the lingual cuspule, the only other reported case was found bilaterally on both the left and right lower first molars of a male individual (irish, 1991). the cuspule is noted to be a triangular shape with a free apex, and located on the distolingual surface just distal to a small metaconulid (irish, 1991). the individual presented in the current study possesses a unilateral expression of the lingual cuspule found on the lower right third molar of a male individual. this expression of the trait is larger, more bulbus at the apex, and more mesially placed than the example described by irish (1991). an example of what here is called the lingual cuspule may also be present on the lower left third molar of a female individual but is recorded there as an expression of the mmtp (marado, 2014: 236). the mmtp is expressed as an ident, pit, or fully developed cusp high on the buccal surface of the protocone (weets, 2009; marado and silva, 2016) whereas the lingual cuspule has been identified as a fully developed cusp found on the lingual surface of the crown. the examples presented here suggest this trait’s expression is consistently found on first and third mandibular molars from both the left and right sides. the third criteria on scott’s (2008) list necessitates the observation of the trait in question across multiple distinct populations. the lingual cuspule has been reported in one individual from the bantu-speaking central sotho from south africa (irish, 1991). the individual presented in the current study is from a native american population in the ohio valley. the possible third example, discussed above, comes from a portuguese population (marado, 2014). additionally, joel irish (1991: 2-3) recalls a. dahlberg observing the lingual cuspule once before in a native american population, though no additional information on this figure 2. lower left third molar from burial a4489-6 (archaic period; mt. cory ohio, handcock county) with a fully developed paraconid (white arrow). 6 dental anthropology 2019 │ volume 32 │ issue 01 example is included. therefore, at present the lingual cuspule has been identified in two populations, south african and native american, with the possibly if its occurrence in a third, portuguese. lack of reporting on the lingual cuspule may be because the trait is being conflated with other paramolar structures, such as the mmtp. although the mmtp is described as occurring on the buccal surface of mandibular molars (weets, 2009; marado and silva, 2016), it is possible that similar expressions on the lingual surface are being lumped together during observation and recording since no formal scoring is in place for lingual expressions. paraconid while the paraconid is a distinct trait, there are no other examples of its expression in modern human populations; therefore, determining a consistent expression within a tooth type, or addressing its prevalence within multiple world populations cannot be attempted here. however, a discussion of paraconid evolution and contextualizing this trait within human dental variation may be more informative. first seen in the mesozoic era, the paraconid is a mandibular principal cusp located on the mesial border between the protoconid and metaconid, as part of the trigonid (gregory, 1922; ungar 2017). the gradual reduction, and then complete loss of the paraconid in primate evolution is contemporaneous with the appearance of the upper molar hypocone (gregory, 1922). by the middle eocene, notharctus (an extinct form of north american adapoidea) exhibits a paraconid of reduced size (gregory, 1922; fleagle, 2013). parapithecids in the oligocene have lost the paraconid altogether, resulting in an absence of this trait in modern cercopithecidae (gregory, 1922; ankel-simons, 2007). although this does not directly speak to hominins and modern humans, based on the lack of acknowledgement in the literature, including a recent review of evolutionary changes associated with hominin and modern human dentition (guatelli-steinberg, 2016), the paraconid appears to have been absent in hominin evolution as well (pers. com. joel irish). because only one individual of the fourty-eight within the study population expresses the paraconid, occurrence within this group can be considered near absent. despite being lost prior to hominin emergence, a cusp that is likely a paraconid is present in a modern human dental arcade. this expression could suggest that humans have not completely lost the ability to express a paraconid. however, the retained ability to develop a paraconid does not seem likely since this cusp was lost with the parapithecids (gregory, 1922) and has only been documented in tarsiers since the oligocene (swindler, 2002; ankel-simons, 2007). alternatively, it is possible that the presence of a paraconid in a modern human is an example of a secondarily derived trait. although it is not common for traits to reappear once lost, there are examples in the dentition where this has occurred (lipson and pilbean, 1982; luo et al., 2004). if other modern human populations also exhibit a remnant paraconid, the discussion could lead to valuable insights into the recent evolution of hominin dentition. conclusions both the lingual cuspule and the paraconid appear to be rare, if not near absent, traits in modern human populations. based on the data presented here, the lingual cuspule has the potential to satisfy the criteria set by scott (2008) and be included in studies of dental morphology and biodistance. if more examples of this trait can be identified, a scoring system could be determined, allowing the lingual cuspule to act as an additional source of information in understanding modern human dental variation. it is currently unclear whether or not the paraconid could be included in biodistance studies as the example presented here is the only one reported in modern humans. looking at this trait from an evolutionary approach, the presence of a paraconid on a modern human tooth could represent an example of a secondarily derived trait. additional examples from a variety of populations are necessary to further discuss what information these two traits could offer in studies of human teeth. acknowledgments these findings are part of a research project funded by the ohio state university alumni grant for graduate research and scholarship, and the larsen research and travel award. i wish to thank ohio history connection for allowing me to conduct research on their collections, and permission to use photographs of dentition. special thanks are given to joel irish for consulting on this “weird” tooth. thank you to tim sefczek for reading drafts of this manuscript. lastly, i thank editors and reviewers of the dental anthropology journal for their comments on this manuscript. references ankel-simons, f. 2007. primate anatomy: an introduction. elsevier, academic press: oxford. fleagle, j.g. 2013. primate adaptation & evolution. elsevier, academic press: london. guatelli-steinberg, d. 2016. what teeth reveal about human evolution. cambridge university press: cambridge. gregory, w.k. 1922. origin and evolution of the human dentition. williams & wilkins company: baltimore. 7 dental anthropology 2019 │ volume 32 │ issue 01 hanihara, t. 2008. morphological variation of major human populations based on nonmetric dental traits. american journal of physical anthropology 136:169-182. hillson, s. 1996. dental anthropology. cambridge university press: cambridge. irish, j.d. 1991. lm1 lingual cuspule in a central sotho dentition from south africa. dental anthropology journal 5(2): 2-3. jernvall, j. & thesleff, i. 2000. reiterative signaling and patterning during mammalian tooth morphogenesis. mechanisms of development 92: 19-29. kraus, b.s. & jordan., r.j. 1965. the human dentition before birth. lea and febiger: philidelphia. lipson, s., & pilbeam, d. 1982. ramapithecus and hominoid evolution. journal of human evolution 11: 545548. luo, z., kielan-jaworowska, z. & cifelli, r.l. 2004. evolution of dental replacement in mammals. bulletin of the carnegie museum of natural history 36: 159175. marado, l.m. 2014. characterization of the dental morphology of a portuguese sample from the 19th and 20th centuries. dissertation, university of coimbra. marado, l.m. & silva, a.m. 2016. the mandibular molar pit-tubercle (mmtp) dental nonmetric trait: comprehensive analysis of a large sample. homojournal of comparative human biology 67: 462-470. martinon-torres, m., bermudez de castro, j.m., martin -frances, l,. garcia-tellez, a., martinez, i., & arsuaga, j.l. 2013. dental morphology of european middle pleistocene populations. in anthropological perspecitives on tooth morphology: genetics, evolution, variation. g richard scott and joel d irish, eds. pp: 201-221. cambridge university press: cambridge. salazar-ciudad i., & jernvall, j. 2002. a gene network model accounting for development and evolution of mammalian teeth. proceedings of the national academy of science 99: 8116-8120. scott, g.r., schmitz, k., heim, k.n., paul, k.s., schomberg, r., & pilloud, m.a. 2018. sinodonty, sunadonty, and the beringian standstill model: issues of timing and migration into the new world. quarterly international 466: 233-246. scott, gr, & irish, j.d. 2017. human tooth crown and root morphology: the arizona state university dental anthropology system. cambridge university press: cambridge. scott, gr, maier, c. & heim, k. 2016. identifying and recording key morphological (nonmetric) crown and root traits. in a companion to dental anthropology. jd irish and gr scott, eds. pp 247-264. wiley blackwell: oxford. scott, g.r. 2008. dental morphology. in biological anthropology of the human skeleton. m. katzenberg a and saunders sr (eds.). willey-liss, inc scott, g.r. & turner, c.g. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge university press: cambridge. simons, e.l. 1989. description of two genera and species of late eocene anthropoidea from egypt. proceedings of the national academy of science 86: 99569960. stojanowski, c.m. & johnson, k.m. 2011. labial talon cusp from the early holocene site of gobero, central sahara desert, niger. international journal of osteoarchaeology 21: 391-406. swindler, d.r. 2002. primate dentition: an introduction to the teeth of non-human primates. cambridge university press: cambridge turner, c.g., nichol, c.r., & scott, g.r. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in advances in dental anthropology. kelley ma and cs larsen, eds. pp: 13-31. john wiley: new york ungar, p.s. 2016. origins and functions of teeth: from “toothed” worms to mammals. in a companion to dental anthropology. irish jd and scott gr (eds.). wiley blackwell: oxford. weets, j.d. 2009. a promising mandibular molar trait in ancient populations of ireland. dental anthropology journal 22(3): 65-72 radlanski 1999.3 pg14.jpg pg15.jpg tasa 1998.3 pg9.jpg pg10.jpg pg11.jpg pg12.jpg newell 2002.6 30 31 development, function and evolution of teeth. edited by mark f. teaford, moya meredith smith and mark w.j. ferguson. new york: cambridge university press. 2000. 314 pp. isbn 0-521-57011-5. $100.00 (cloth). with the advent of new technologies and new methods of analysis, there has been an exponential increase in the quantity of information resulting from scientific investigation. these advances have opened new perspectives in research, as well as facilitating new approaches to old questions. such developments have led to the burgeoning of new fields of inquiry and areas of increased specialization. unfortunately, with this expansion, it is ever easier as editor teaford points out, to ‘lose sight of the forest among the trees’ and dental research is not exempt from this myopia. this ambitious volume, edited by teaford, smith and ferguson, successfully counters this situation by broadening the channels of communication between diverse disciplines and clearly demonstrating the interrelatedness of the multiple perspectives addressing questions of dental morphology. resulting from the symposium “teeth: homeoboxes to function” at the 4th international congress of vertebrate morphology at the university of chicago, the editors have united the contributions of experts from a wide range of perspectives on the morphology of teeth. with chapters that provide overviews of “a wide range of dental topics, linking genes, molecules and developmental mechanisms within an evolutionary framework”, this volume demonstrates the numerous approaches that the field of dental morphology now encompasses. the book is divided into four parts, reflecting the study of increasing levels of organization; molecules and genes, tissues, teeth and dentition, and “macrostructure”. in this way, each section provides a foundation for subsequent levels of analysis. part one, “genes, molecules and tooth initiation” contains four chapters that attempt to move beyond descriptions of developmental processes at the molecular level to discern the mechanisms involved in tooth formation. in the first chapter, sharpe discusses the role that homeobox genes play in organogenesis and the potential function these genes and homeoproteins have in the development of the orofacial region, particularly the regulation of tooth position and shape. chapter two furthers the discussion of developmental control in teeth. jernvall and thesleff focus on epithelial enamel knots and their function as mediators of cusp development. though these structures have long been described, their role in the morphogenesis of single and multicusped teeth has only recently begun to be understood. in the third chapter, ruch and lesot discuss the molecular signaling involved in the terminal differentiation of odontoblasts and their role in the formation of dentine. this section concludes with a chapter by fincham et al., in which the authors review the strides made to date in understanding the role of enamel genes in the assembly and disassembly of the organic extracellular matrix during enamel formation and maturation. part two addresses the evolution and development of dental tissues. building on the third chapter, chapters five and six focus on dentine. smith and sansom begin with a synthetic presentation of the evolution of dentine, considering the possible functional advantages of this tissue in the dermal armor of early vertebrates. chapter six, by smith, examines the functional interdependence of dentine and pulp during reactionary dentinogenesis (initial tissue formation) and reparative dentinogenesis (repair after injury to the tissue). sander’s provides an overview of the diversity of enamel in reptiles and presents a model for the evolution of prismatic enamel in mesozoic mammals. in chapter eight, von koenigswald’s paper continues the discussion of mammalian enamel, comparing the enamel microstructure of marsupials and placentals. he asserts that the enamel of both subclasses is formed by the same enamel types, reflecting their common heritage. however, the frequency of these types and the structural elements they form differ. this further differentiation of enamel types between eutheria and marsupiala is considered the result of convergent evolution. this section ends with dean’s chapter on the utility of incremental growth marks in enamel and dentine in both fossil and extant species. it is noted that the differential rates of enamel formation in humans and apes are identifiable, yet the rates of dentinogenesis do not vary. continuing the pattern of increasing organizational complexity, part three is entitled “evolution of tooth shape and dentition.” this section begins with smith and coates’ argument that the previously established theories of tooth and jaw development as a functional unit are not supported by more recent data. based on fossil evidence, they claim that the development of jaws and teeth were distinct events, with “jaws originating for suspension or suction feeding and teeth for food apprehension or sampling….” zhao et al. provide an overview of the evolution of dentition patterns (number, location and arrangement of differently shaped teeth) and review various models (e.g., gradient, clone, homeobox genes) put forth to explain the developmental mechanisms behind these patterns. the authors find that none of the current models are established by “convincing experimental data”, yet assert that ongoing genetic and molecular advances (such as those reported in part one of this volume) will continue to shed light on the mechanisms of dentition pattern formation. gaengler focuses on the periodontal attachments that have been developed in vertebrates to contribute to an understanding of the phylogeny of dentition “in its broadest sense”. in an examination of the polyphyodontic dentition of book review 30 31 non-mammalian vertebrates, berkovitz reports that patterns of replacement in these teeth are related to continuous growth in body size. the most common pattern involves waves of alternating teeth, preventing the organism from an extensive lack of teeth at any point in the process. in chapter 14, butler presents a detailed review of the variation in primate tooth shape and discusses how these variations are functionally adaptive for an arboreal lifestyle. in the final chapter of the section, smith reevaluates ‘schultz’s rule’ (“the tendency for replacing teeth to come in relatively early in slow-growing, longer-lived species”) in light of new data from primates. additionally, she examines the applicability of this rule to the tooth emergence patterns of other mammals, specifically ungulates. according to her research, schultz’s rule is supported by recent primate data, as well as data from insectivores. however it cannot explain the variation present among the ungulates, particularly the more specialized species. the focus of the final section is the “macrostructure and function” of teeth. it begins with huysseune’s exploration of the environmentally induced variability of phenotypes in the dentition of african cichlids. in this case, phenotype varies in relation to the hardness of diet. chapter 17, by shellis and dibdin, addresses the influence of enamel pores on the optical and mechanical properties of this tissue. rensberger provides a review of the morphologies of mammalian enamel, examining the functional basis for this differentiation. he then examines how the attributes of abrasion and fracture resistance at the microscopic level create selection pressures at the macroscopic level. jernvall et al. present a case in which they apply their method of classifying molars to the dental evolution of hooved mammals. based on their analysis, the authors establish five patterns in this evolutionary history and suggest relationships between these trends and patterns of ungulate radiation. the function of postcanine teeth in mastication is the foundation of lucas and peters’ chapter, in which they examine the advantages of certain tooth shapes in the mastication of particular foods. by comparing the material properties of food (strength, toughness and young’s modulus) and the shape of teeth, specifically the sharpness or bluntness of the occlusal surfaces, the authors highlight the selective advantages of both tooth shapes relative to diet. teaford’s final chapter in the book reintroduces many of the themes presented in the contributed papers of this volume. by reviewing the microscopic and macroscopic perspectives, the insights each has provided and the promise of future contributions, the editor again underscores the importance of the integrative approach to the study of dental functional morphology. by design, this book is relevant to many with research interests in teeth, regardless of specialization. though the contributing authors come from a wide range of disciplines, most of the papers do not require highly specialized knowledge of the particular field. many papers begin with an introduction in which terminology is standardized or taxonomic relationships are indicated, making the paper accessible to those outside the author’s immediate area of specialization. at the first scan of the book the direct relevance of some of the papers to a dental anthropologist may not be readily apparent. however, upon reading the text, one is continuously reminded of the necessity of being familiar with these many perspectives relating to tooth morphology. with the likelihood of continued advancements in these many related areas, such collaborative endeavors as the book are necessary to make best use of this new information and should be commended and emulated. elizabeth a. newell department of sociology and anthropology elizabethtown college elizabethtown, pa 17601 book review dental symposium at 2003 aapa meeting heather edgar and loren lease, from the university of ohio, have organized a poster symposium through the auspices of the dental anthropology association for the 2003 meeting of the american association of physical anthropologists to be held in tempe, arizona, this coming april. details will be printed in the next issue of dental anthropology. please make plans to attend this official da function. edgar and sciulli 2004.4 24 25 during data collection for a larger study (edgar, 2002), it was noted that some mandibular premolars were more rectangular than ‘normal’ premolars. the affected teeth appear to be either compressed in the buccolingual dimension or longer in the mesiodistal dimension. the affected premolar is thus more rectangular or elliptical than hexagonal or rounded, like most mandibular premolars. additionally, the cusps of the affected premolars appear closer together, and somewhat angled toward each other in some cases. although affected posterior mandibular premolars were noted, more anterior premolars were seen with this condition. materials a total of 458 individual dentitions were examined for the presence of affected premolars. a list of the samples from which these individuals were drawn, their ancestry, and the frequency of trait presence is listed in table 1. in these dentitions 19 elongated mandibular premolars were noted, 14 anterior and five posterior. methods measurements were made of 14 affected and 22 non-affected anterior premolars. all individuals are represented by the following three measurements: mesiodistal diameter (md): this measure was the greatest length of the tooth in the mesiodistal plane. adjustments were made if the tooth was rotated out of ‘normal’ occlusion (goose, 1963; hillson, 1986, 1996; moorrees, 1957; moorrees et al., 1957). teeth with excessive wear were excluded from the study (keiser, 1990). buccolingual diameter (bl): the maximum diameter of the tooth crown perpendicular to the md measurement (goose, 63; hillson, 1986, 1996; moorrees, 1957; moorrees et al. , 1957). cusp distance (cd): this is a measure of the distance between apices of the two main cusps of the premolar, one buccal and one lingual. if more than one lingual cusp was present, the largest cusp was the one included in the measurement. if there was no lingual cusp, the measure was taken from the apex of the buccal cusp to the center of the lingual marginal ridge. in order to investigate the nature of the size and shape differences between the affected and non-affected premolars, we performed principal components analysis (pca) on the logarithmically transformed bl, md, and cd dimensions. we used this approach as it allows the analysis of variation in the premolars to include multiple measures, while accounting for the interaction among the measures. noting the pattern of these relationships often provides insights into the relationships between the size and shape of features as well as how size and shape interact in the development of the feature (jolicoeur, 1963). pca was performed with sas software (sas statistical institute, 2003). the calculation of the principal components of a covariance matrix yields the direction cosines and lengths of the principal axes of elongated mandibular premolar: a new morphological variant heather j. h. edgar* and paul w. sciulli** *maxwell museum of anthropology, university of new mexico, albuquerque, new mexico **department of anthropology, the ohio state university, columbus, ohio abstract a previously unreported morphological variant, elongated premolar, is described and analyzed. the elongated premolar is mandibular and may affect the anterior or posterior premolar in the field. it appears phenotypically to be more rectangular (with the long axis mesiodistal) than ‘normal’ premolars. dentitions of european americans, african americans, and an admixed group of native african/european americans were examined for the presence of this characteristic. elongated premolars were found in 19 teeth in the 458 individuals included in the study. mesiodistal diameter, buccolingual diameter, and cusp distance were measured for 14 affected and 22 unaffected anterior premolars. principal components analysis shows that elongated and non-elongated premolars differ primarily in shape and not size, with elongated premolars attaining their overall shape due primarily to an increase in the mesiodistal dimension. thus, the suggested description of this feature is elongated premolar (referring to the mesiodistal dimension), rather than compressed premolar (referring to the buccolingual dimension). dental anthropology 2004;17(1):24-27. *address for correspondence: heather h. j. edgar, maxwell museum of anthropology, msc01 1050, 1 university of new mexico, albuquerque, new mexico 87131-0001 e-mail: hjhedgar@unm.edu e-mail: hjhedgar@unm.edu 24 25 the multidimensional scatter of points. this will show which combination of features is most variable and uncorrelated with each other. the eigenvector matrix contains the direction cosines of the principal axes. if all of the direction cosines of an eigenvector are of the same sign, this axis represents a simultaneous increase (or decrease) in all of the features, and is usually considered to represent size variation. if, on the other hand, the signs of the direction cosines differ, then some features increase while others decrease. axes of this sort are often considered to reflect shape variation, as this represents an increase in some dimensions and a simultaneous decrease in others. in addition to differences in sign, the direction cosines may differ in magnitude. for example, if a feature increased in such a way that the proportions of all dimensions remained constant, then the relations among the dimensions would be isometric. this situation will be reflected in the direction cosines of an eigenvector when they all have the same sign and magnitude equal to 1/√p, where p is the number of variables. results figures 1 and 2 are affected anterior and posterior premolars, respectively. if every dentition examined in this study contained a full complement of mandibular premolars, 1,832 teeth would have been examined, and the trait frequency of expression would be 1.09%. however, a minority of observed dentitions was incomplete, so the actual frequency of the trait expression is somewhat higher. out of the 458 dentitions observed, 14 had at least one affected tooth, giving a sample frequency of 3.06%. of these 14, seven individuals showed unilateral expression in an anterior premolar, four showed unilateral expression in a posterior premolar, two showed bilateral expression in the anterior premolars, and one showed expression in both one anterior and one posterior premolars. table 2 contains the results of the pca of the affected and unaffected premolar samples. in the unaffected sample the direction cosines of the first axis are all the same sign, indicating this axis represents size variation. this observed first eigenvector differs from hypothetical isometry (0.5774 0.5774 0.5774) by only 45°, indicating that the proportions of all dimensions are constant. the second and third axes have direction cosines of differing signs indicating that they represent shape variation. the second axis shows direction cosines for the bl and md dimensions of the same sign and approximate magnitude, while the direction cosine corresponding to the cd dimension is about 2.5 times smaller. the third axis from the pca of the unaffected sample represents a contrast between the bl and md dimensions, with the former increasing while the latter decreases. in the affected premolar sample, the direction cosines of the first axis are all of the same sign. this axis, like the first axis of the unaffected premolar sample, represents size variation. however, unlike the first axis of the unaffected premolar sample, the first axis of the affected premolar sample does not appear to represent isometry. the direction cosine of the md diameter is about 1.5 times smaller than those of the bl and cd dimensions, and the eigenvector differs from hypothetical isometry by 14.6°. the second and third axes of the affected premolar sample, like the sample of unaffected premolars, contain direction cosines with different signs, indicating these two axes represent fig 1. elongated anterior premolars. bilaterally, the anterior premolars exhibit a marked reduction in size of the buccolingual dimension, but no loss of mesiodistal length. fig 2. elongated posterior premolars. the two posterior premolars, but notably the tooth on the right, is compressed buccolingually, but no loss of mesiodistal length. elongated premolars 26 27 shape variation. both the second and third axes show a large direction cosine for the md dimension in relation to the bl dimension. compared to the sample of unaffected premolars the md dimension on the second and third axes of the affected premolars represents a much larger relative increase. the direction cosine for the cd dimension on the second and third axes have the same sign as in the sample of unaffected premolars, but with a smaller magnitude in the second axis and a greater magnitude in the third axis. conclusions in the pca results for both unaffected and affected premolars, the first axis represents size variation. the measures of the unaffected premolars are isometric on the first axis, but the affected premolars deviate from unaffected n=22 eigenvector matrix means means 1 2 3 log e raw bl 0.6020 0.3915 0.6959 2.0374 4.67 md 0.6142 0.3300 -0.7169 2.0156 7.51 cd 0.5103 -0.8590 0.0419 1.5613 4.77 λ i 75.2% 18.9% 5.9% affected n=44 eigenvector matrix means means 1 2 3 log e raw bl 0.6016 0.3234 -0.7304 1.9882 7.30 md 0.3926 0.6767 0.6229 2.0600 7.8 cd 0.6957 -0.6615 0.2801 1.5555 4.73 λ i 76.2% 17.3% 6.5% table 2. eigenvector matrices, percent of total variation accounted for by the eigenvalues, and mean vectors from pca of logrithmically transformed bl, md, and cd dimensions. isometry, with the bl dimension being larger that the md. this result is not expected, as the affected premolars appear to be narrower in the bl direction. however, the first axis of the affected premolar may simply reflect the general size component of premolars in which increase in the bl dimension is fairly constant. the second and third axes represent shape variation in both premolar samples, and it is in these axes that the overall phenotypic differences are manifest. for the unaffected premolar sample, in the second axis, the bl and md direction cosines are approximately equal and the cd direction cosine is larger in magnitude but of opposite sign. in the third axis the direction cosine of the bl dimension is greater than that of the md dimension, and the cd dimension direction cosine is negligible. these results describe a ‘normal’ premolar that is generally oval in outline, with the bl dimension slightly affected group ancestry reference n anterior posterior new york twins european american osborne et al., 1958 102 4 1 u t memphis european american lease and harris, 2001; edgar, 2002 101 0 0 african american 100 1 3 gullah african american menegaz-bock, 1968; edgar, 2002 55 9 1 hollister-haliwa native american african american european american menegaz-bock, 1968 100 0 0 totals 458 14 5 table 1. sample materials. h.j.h. edgar and p.w. sciulli 26 27elongated premolars larger than the md. for the affected premolar sample, the direction cosine for the md dimension is somewhat larger than the bl direction cosine in the second axis, and much larger than the bl direction cosine in the third axis. the direction cosine of the cd dimension is not as small in the second axis as it is in the unaffected sample, and it is larger in the third axis than in the ‘normal’ sample. this pattern of interaction describes a tooth that is primarily elongated in the md direction, more rectangular than ‘normal’ premolars, and with cusps somewhat closer together. it should be noted that elongated premolars are detectable as a morphological variant. it is not necessary to perform metric analysis to include an observation of its presence or absence in a morphological analysis of a dentition. the metric analysis described here was performed simply to determine if the final phenotype was the result of a predominant reduction in bl growth or and extension of md growth. we are interested to hear from other researchers who may have noted this characteristic and/or have data concerning its expression and frequency. literature cited edgar hjh. 2002. biological distance and the african american dentition. ph.d. dissertation, ohio state university. goose dh. 1963. dental measurement: an assessment of its value in anthropological studies. in: brothwell dr, editor. dental anthropology. london: pergamon press, p 263-270. hillson sw. 1986. teeth. cambridge: cambridge university press. hillson sw. 1996. dental anthropology. cambridge: cambridge university press. jolicoeur p. 1963. the multivariate generalization of the allometry equation. biometrics 19:497-499. keiser ja. 1990. human adult odontometrics. cambridge: cambridge university press. lease lr, harris ef. 2001. absence of association between body size and deciduous tooth size in american black children. dental anthropology 15: 7-12. menegaz-bock rm. 1968. an investigation of the genetic basis for structural relationships in the anterior dentition. ph.d. dissertation, university of chicago. moorrees cfa. 1957. the aleut dentition. cambridge: harvard university press. moorrees cfa, thomsen so, jensen e, yen pkj. 1957. mesiodistal crown diameters of deciduous and permanent teeth. j dent res 36:39-47. osborne rh, horowitz sl, de george fv. 1958. genetic variation of tooth dimensions: a twin study of the permanent anterior teeth. am j hum gen 10:350356. sas statistical institute inc., 2003. 13th international symposium on dental morphology the organizing committee of the 13th international symposium on dental morphology has announced the dates and location of the next symposium on dental morphology. the committee is headed by dr. elzbieta zadzinska, and the symposium dates are from wednesday 24th to saturday 27th, august, 2005. the venue will be in lodz, poland. the committee announces that the deadline for preregistration is 10 june 2004, so the committee can get a sense of the potentional number of participants. organizing committee address: chair of anthropology university of lodz banacha 12/16 90-237 lodz poland e-mail: dental@biol.uni.lodz.pl fax: +48 42 635-44-13 more information will be supplied as it becomes available from the organizing committee the editor the cathedral in lodz mailto:dental@biol.uni.lodz.pl hojo 2005.5 61 macroscopic tooth wear has been investigated with relation to tooth use and diets among numerous different cultures, and various tooth-wear scoring systems have been devised to record the range and pattern of variation (e.g., bullington, 1991; hinton, 1981; molnar 1971; scott, 1978; walker, 1978). such scoring systems depend on overall observations of the occlusal surfaces. but, it also is informative to examine the patterns of tooth wear microscopically because dental microwear reveals that different small regions of a crown are used for processing different foods—and processing food in different ways. thus, the patterns of microwear differ among various animals corresponding to their diets (walker et al., 1978). subsequent to walker’s investigation of microwear of mammalian teeth as an indicator of diet, the assessment of dental microwear on facets has been applied to the study of tooth use and diets of non-human primates and of humans (e.g., gordon, 1982; hojo, 1991, 1996; teaford, 1988; 1994, 1996). while my previous study reported overall observations on dental microwear of late stone age (neolithic age) and early modern people (hojo, 1989), the present study identifies regional difference of dental microwear features on four small occlusal areas of a heavily worn occlusal surface of an m 2 of neolithic japan using microwear image analyzing software version 2.2β (ungar, 1996). pits on the heavily worn surfaces of teeth have been found in hard-diet eaters (hojo, 1991; teaford, 1994, 1996). in the present study, the high frequency and various sizes of pits on an m 2 of neolithic japan suggest regional differences of dental microwear on the occlusal surface of an m2 from neolithic japan: a case study teruyuki hojo yahatanisi mitusada 3-19-5, kitakyushu city, 807-0805, japan university of sangyoidal, school of medicine, institute of anatomy, anthropology and sem correspondence to: teruyuki hojo, yahatanisi mitusada 3-19-5, kitakyushu city, 807-0805, japan university of sangyoidai, school of medicine, institute of anthropology and sem e-mail: rhnyb554@yahoo.co.jp a variety of hard foods and hard fine sand grains in the foods of japanese neolithic people. direct evidence of the use of wild vegetables, such as wild yams for grinding, was not found in this neolithic site, but evidence of wild yams, wild chestnuts and other wild vegetables often are found in neolithic sites. also, their foods would become hard through dehydration for preservation. furthermore, smooth stones and jōmon style pottery were found in the present archaeological site. such worked stones could be used for grinding and cutting hard foods (animal meats, bones, and clams), and fragments of pottery may have been used for food processing. the various sizes of pits and striations recorded in this study could be related to the size of grains that were incorporated into foods from stone tools as part of the people’s hunter-gathering economy. materials and methods an m 2 from neolithic japan was of an adult male excavated from the kakiwara shell mound in western kyusyu japan (matsuno et al., 1967). to avoid damage to the tooth, a high-resolution cast specimen was used. this is because of the risk during the dehydration process or in the specimen chamber of the sem (scanning electron microscope) that teeth can easily be broken. the highabstract regional differences of dental microwear among four small areas on the heavily worn occlusal surface of a mandibular m2 of an adult male from neolithic japan were investigated using a scanning electron microscope (sem). the m2 specimen was cast using a high-resolution epoxy resin under low pressure for sem, and the cast specimen was sputter-coated with gold. among the four regions of the m2, two (facets 3 and 9) showed higher proportions of pits (78.6% and 75.0%, respectively), and the two others (lingual marginal facet 7n, and the inner side of facet 7n) showed lower proportions of pits (5.6% and 33.3%, respectively). the two pitted regions seem to reflect the processing of hard foods, and the two other regions with higher frequencies of striations might reflect exposures to less gritty, softer foods. the variation of these pits and striations suggests that the jomon subsisted on stone-processed hard foods, with coarse grain sizes of sand in foods that included tuberous roots, animal meats with bones, and clams. the analyses of regional differences of dental microwear will develop important ways to study tooth use and past diets. dental anthropology 2005;18(2):61-64. 62 resolution cast of the m 2 was made with a standard technique (e.g., hojo, 1989, 1991, 1996; teaford, 1994): first, an impression was taken using a polysiloxane impression material (coltene, “light-body”). second, a low-viscosity epoxy resin (ciba-geigy, “araldite”) was used to make the positive cast. then, the high-resolution specimen cast was sputter-coated and inspected with an abt sx-40a sem (akashi-beam technology, tokyo japan) at magnifications ranging from 7x to 500x at 25kv. the four regions noted in figure 1 were closely scanned by sem as follows: the site labeled 2a was on facet 3; 2b was on facet 9; 2c was on the lingual marginal facet 7n, and 2d was on the inner side of facet 7n. facets 3, 9, and 7n were labeled following kay (e.g., kay, 1977; gordon, 1982). the lengths and widths of pits and striations were measured at the magnification of 500x using microwear image analyzing software version 2.2β (ungar, 1996). results and discussion the macroscopic scoring system of scott (1979) was applied to the heavily worn occlusal surface of the m 2 from neolithic japan. this specimen was from an adult male, and the attrition score was 8 as can be seen in figure 1. measurements of pits and striations on the four regions of the m 2 (fig. 1) were analyzed through digitization of the wear marks (ungar, 1996), and the percentages of pits were high in two regions 2a and 2b (table 1, fig. 3). region 2c showed the highest proportion of striations (94.4%; table 1, fig. 3). region 2d showed a higher proportion of striations (66.7%; table 1, fig. 3) than regions 2a or 2b. all measurements were computed using a 4:1 ratio of length to width as a cut-off between pits and striations just as suggested by teaford (1988) and ungar (1996). the mean breadth of the pits of the region 2c was the smallest (table 1; fig. 4). as for the mean breadth of the pits, the difference between the region 2c and 2d was not statistically significant, but the difference between the region 2b and 2c was highly statistically significant by t-test (p < 0.001), and between regions 2b and 2d also was significant (t-test, p < 0.001). two regions (2a and 2b) showed higher proportions of pits (78.6% and 75.0%, respectively) and broader pits (17.0 microns and 16.4 microns, respectively). the two other regions (2c and 2d) showed lower proportions of pits (5.6% and 33.3%, respectively) and smaller pits (6.8 microns and 8.0 microns, respectively). because pits are considered to be related to the processing of hard foods (hojo, 1991; teaford, 1994, 1996), such numerous and broad pits in the two regions (2a and 2b) suggest that big sand grains might be adhered to the foods in everyday life of the neolithic age (figs. 3 and 4). surprisingly, the highest percentage of pits, 78.6% in region 2a, is higher than that of the hard-diet primate, cercocebus albigena, with 55.2% pits (teaford, 1988). and as for mean pit breadths, region 2a striations pits n mean sd n mean sd % of pits 2a length 3 75.6 15.0 11 24.2 12.8 78.6 breadth 3 3.5 1.5 11 17.0 8.0 2b length 5 39.3 17.4 15 28.9 13.2 75.0 breadth 5 5.5 3.1 15 16.4 8.8 2c length 51 55.6 28.8 3 18.1 14.4 5.6 breadth 51 1.9 0.9 3 6.8 5.6 2d length 16 40.3 18.4 8 23.3 9.9 33.3 breadth 16 5.0 1.6 8 8.0 3.0 table 1. m 2 microwear in neolithic japanese (microns) fig. 1. a heavily worn surface of an m 2 from neolithic japan in overall view using sem. four small regions are labeled (2a, 2b, 2c, 2d). the lingual side is up, and the mesial side is right. bar = 1,000 microns. t. hojo 63regional microwear on m2 fig. 2. figures of four regions (2a, 2b, 2c, and 2d) of sem that are identified in figure 1. pits are preponderant in 2a, and 2b, and the broadest pits are seen in 2b. many thin striations and a few pits are observed in 2c, and in 2d. pits in 2c and in 2d are less common than those in 2a and in 2b. bar = 20 microns. and 2b exhibited mean breadths of 17.0 microns and 16.4 microns, respectively, (table 1; fig. 4), but the mean for cercocebus albigena was just 9.9 microns (teaford, 1988). this suggests that the two regions (2a and 2b) of this neolithic m 2 had been abraded by harder and bigger sand grains and substances than the extreme hard-diet primate cercocebus albigena. the difference of the mean breadth of striations (table 1) between regions 2a and 2b was not statistically significant, but the mean breadth of striations of 2b was significantly broader than that of 2c by t-test (p < 0.001). the mean breadth of striations was thinnest in region 2c (fig. 4). the image of the region 2c looks like those of soft-food eaters, colobus guereza (that has a mean breadth of striations of 1.2 microns; teaford, 1988). the region 2c may represent the processing of soft food. the differences of the lengths of striations (table 1) among the four regions were statistically insignificant in multivariate analysis. in brief, measurements of dental microwear for various primate species (teaford, 1988) suggest that these human four patterns of dental microwear reflect the processing of foods that have incorporated different grain sizes. the grains that abraded the regions 2c and 2d are suggested to be smaller than the two others. among recent microscopic analyses of tooth wear, there have been interesting experimental studies of dietinduced changes of human tooth wear, for instance, a case of stone-ground maize populations was reported by teaford (1996). the variation in microwear features in the present study may be related to various kinds of foods. in the environment of this neolithic human, the foods probably included wild tuberous roots, clams, fish, and animal meat and bones. even now, in southwestern japan, both cultivated and wild yams and other wild tuberous roots commonly are eaten. in japan, stoneground flour has been used widely. until now, the flour of traditional noodles has been made by stone grinding. additionally, in neolithic japan (late stone age) some wild vegetables, chestnuts and walnuts were dried for preservation for use out of season, and these would later be stone-ground as were other vegetable roots just as in 64 regional microwear on m2 modern japan. worked stones in this neolithic site might have been used for grinding and cutting hard foods, and small grains from these stones would be incorporated into the food, just as stone-ground maize was part of the diets of various prehistoric populations (hinton, 1981). characteristic changes of dental microwear would be induced by stone-ground maize (teaford, 1996). it is anticipated that the further analyses of regional differences of dental microwear will develop important insights into tooth use and prehistoric dietary practices. literature cited bullington j. 1991. dental microwear of prehistoric juveniles from the lower illinois river valley. am j phys anthropol 84:59-73. gordon kd. 1982. a study of microwear on chimpanzee molars: implications for dental microwear analysis. am j phys anthropol 59:195-215. hinton rj. 1981. form and patterning of anterior tooth wear among aboriginal human groups. am j phys anthropol 54:555-564. hojo t. 1989. dietary differences and microwear on the teeth of late stone age and early modern people from western japan. scanning micros 3:623-628. hojo t. 1991. scanning electron microscopic analyses of dental wear on the heavily worn second molars of the wild japanese monkeys (macaca fuscata). scanning micros 5:505-508. hojo t. 1996. quantitative analyses of microwear and honing on the sloping crest of the p3 in female japanese monkeys (macaca fuscata). scanning micros 10;727-736. kay rf. 1977. the evolution of molar occlusion in the cercopithecidae and early catarrhines. am j phys anthropol 46:327-352. matsuno s, chigoi y, nagata t. 1967. on the human skeletons from kakiwara shell mound in rokka, kashima village, kamimashiki-gun, higo, japan. j kumamoto med soc 41:41-52. molnar s. 1971. human tooth wear, tooth function and cultural variability. am j phys anthropol 34;175-190. scott ec. 1979. dental wear scoring technique. am j phys anthropol 51:213-218. teaford mf. 1988. a review of dental microwear and diet in modern mammals. scanning micros 2:1149-1166. teaford mf. 1994. dental microwear and dental function. in: evolutionary anthropology, vol. 3. new york: wiley-liss, inc, p 17-30. teaford mf. 1996. brief communication: diet-induced changes in rates of human tooth microwear: a case study involving stone-ground maize. am j phys anthropol 100:143-147. ungar ps. 1996. microwear image analysis software. version 2.2β. (version 4.0 now available online at http://pungar@uark.edu/) walker a, hoeck hn, perez l. 1978. microwear of mammalian teeth as an indicator of diet. science 201;908-910. walker pl. 1978. a quantitative analysis of dental attrition rates in the santa barbara channel area. am j phys anthropol 48:101-106. fig. 3. frequencies of pits and striations on the four regions of the m 2 were analyzed through digitization of the wear marks (ungar, 1996). pits of two regions (2a and 2b) showed higher proportions than the two other regions (2c and 2d), which, in turn, showed higher frequencies of striations than the other two regions (2a and 2b). fig. 4. measurements of pits and striations on the four regions of the m 2 were analyzed through digitization of the wear marks (ungar, 1996). the mean breadth of the pits of the region 2c was the most narrow. pits of two regions (2a and 2b) were broader with higher proportions. 2a 2b 2c 2d 0 20 40 60 80 100 % o f p it s a n d s tr ia ti o n s 78.6 21.4 75.0 25.0 5.6 94.4 33.3 66.7 p it s s tr ia ti o n s 2a 2b 2c 2d 0 5 10 15 20 25 30 35 % o f p it s a n d s tr ia ti o n s 24.2 17.0 28.9 16.4 18.1 6.8 23.3 8.0 l e n g th b re a d th tucker 2002.5 26 27 biological anthropology of the human skeleton. edited by m. anne katzenberg and shelley r. saunders. new york, toronto. wiley-liss, inc., 2000. 504 pp. isbn 0-471-31616-4. $80.75, cloth. this exciting and comprehensive volume, detailing methods of bioanthropological research as applied to the human skeleton, brings together 21authors in 16 chapters. an initial impulse is to compare this work with the 1992 book edited by saunders and katzenberg, skeletal biology of past peoples: research methods, as many of the same authors appear in both volumes. however, to characterize this book as an updated version of the 1992 volume is to grossly misrepresent this work. on closer inspection, it is clear that the editors have adopted a mature approach to the biocultural study of the human skeleton. many contributors are cautionary, but not pessimistic as they discuss in detail the limitations associated with bioarchaeological research, while other chapters portray practical applications for describing and analyzing biological data. the definitive theme of the book is to report advanced methods in skeletal and dental research, however a welcome addition is the introductory chapter on ethics in bioarchaeology. the book is divided into five parts, with the first section consisting of two chapters devoted to theory and application in studies of past peoples. the remaining four sections emphasize current perspectives for specific areas of skeletal and dental anthropology such as morphological analyses, paleopathology, chemical analyses of bone (including adna research), aging techniques, and quantitative applications. in the first chapter, p. walker sharply focuses the reader’s attention to bioethics and addresses the moral conflicts associated with bioarchaeological research. walker presents the historical background for research on human remains highlighting the paradoxical position of bioarchaeology with its roots both in medicine and anthropology (p. 3). one strength of this chapter is that walker provides a framework for discourse between bioarchaeologists and indigenous populations—a discourse that employs respect born from historical perspective and understanding. in the second chapter, d. ubelaker examines forensic anthropology. again, a historical background provides a basis for understanding that the “theoretical approach employed in forensic anthropology basically involves a broad anthropological population perspective applied to the individual” (p 49). ublelaker reviews the methods employed in forensic anthropology and supports that the future of forensic research is bright. part two consists of five chapters concerning morphological analyses and age changes. c. ruff presents an overview of biomechanical research as applied in the reconstruction of past human behavior. he discusses different methods for structural analysis of long bones and reviews the exciting results of biomechanical studies as applied to long term evolutionary trends, microevolutionary changes and variation within an individual’s lifetime. students looking for a detailed discussion on dental morphology recording strategies will be thrilled to read j. mayhall’s chapter. mayhall provides extensive descriptions of morphological methods and notes the strengths and limits of each technique. he emphasizes that dental morphological studies should employ methods that are consistent, easily achievable, and comparable with other studies. s. saunders takes a careful look at subadult growth studies as indicators of past population health and applies a practical perspective for addressing some of the problems associated with these studies. she explores issues such as the recovery of an unbiased sample of subadults, the limits of sexing subadults and the inherent difficulties associated with age estimation techniques. although cautionary, saunders stresses that the potential of data recovered from living individuals, forensic cases, historic cemeteries as well as adna techniques and histology may serve to clarify age estimation in subadult skeletons and provide population specific databases for testing growth study assumptions. c. fitzgerald and j.c. rose discuss exciting methods for assessing subadult age using dental growth markers. the authors provide a generous review of dental anatomy, which allows the reader to understand how enamel is formed and thus how enamel microstructures can be used to determine subadult age. a major strength of this chapter is its practical focus, which includes discussions on preparation of tooth samples, microscopy as well as image analysis. a. robling and s. stout review the physiology and histomorphology of cortical bone and provide a synthesis of histomorphometric age estimation research. the authors include discussions of several factors that affect histological age estimates at both the physiological and methodological level. again, the practical perspective must be applauded which includes worked examples of age estimation methods in the appendix. part three presents three chapters detailing current methods and research in prehistoric health and disease. n. lovell examines several methods used in paleopathological research such as gross macroscopic observations, radiographic methods, computed tomography, magnetic resonance imaging, endoscopy, microscopic methods, and biochemical methods. she cautions that although paleopathology is the discipline that “aims to reconstruct the history and geography of disease” it is mostly restricted to lesions from trauma and chronic conditions (p. 217). she states that researchers must consider the larger role of disease as factors in biocultural evolution in order for paleopathology to have relevance outside our scientific community. s. hillson reviews methods for evaluating dental pathology and provides extensive discussions on developmental defects of enamel, dental wear, dental calculus, caries 28 29 and periodontal disease. hillson reminds the reader that the pathologies reflected in the human mouth are linked and their pattern of progression is complex and can sometimes interact in contrasting ways. therefore it is important that the recording systems and analyses of dental pathology reflect accurate life processes. hillson provides excellent advice for recording and evaluating dental data and presents a scoring system for caries and periodontal disease (pp. 273-280). the final chapter in this section reviews palaehistological methods as a technique in evaluating health and disease. s. pfeiffer stresses that the size and organization of osteons, haversion canals, and other bone microstructures provide telltale clues in reconstructing past human life. pfeiffer describes methods for obtaining, preparing and analyzing samples. she also presents research from different studies that employ palaehistological methods in evaluating bone structure variation, health and disease. part four, chemical and genetic analyses of hard tissues, includes three chapters that explore stable isotope, trace element, and ancient dna analyses. m.a. katzenberg provides a mature look at stable isotope analyses and how these studies are integrated with other biocultural questions and themes. she reviews methods for obtaining samples and presents research studies that employ stable isotope techniques to reconstruct diet, determine infant weaning strategies, identify pathological bone changes and identify residence and migration patterns. m. k. sandford and d. s. weaver present a frank discussion on elemental analyses in skeletal research, emphasizing the confounding affects of diagensis. the authors review bone chemistry, biogenic and diagenetic processes and conclude with a plea for “genuine interdisciplinary collaborations and more specialized, up-to date training of our students” (p. 344). a. c. stone reviews the methods for recovering ancient dna, drawing attention to how dna is preserved and modified in the original environment and during subsequent extraction. stone cautions that there are still challenges within the field, such as experimental design and contamination of samples, but also demonstrates the potential rewards for this area of research. through numerous examples, stone demonstrates how molecular archaeology can be used as supplemental verification for traditional anthropological questions or provide unique evidence such as in the identification of specific pathogens. the final section of the book contains three chapters that emphasize quantitative methods and population studies. m. pietrusewksy presents a nontechnical discussion for using multivariate statistical methods in analyzing morphometric data. starting with the assumptions used in biological distance studies, pietrusewksy provides a step by step review of quantitative techniques and ultimately focuses on current computer statistical packages. examples of pietrusewksy’s personal research in craniometric analyses provide excellent references for use in comparison studies. m. jackes offers a thoughtprovoking discussion on adult age determination and portrays a clear depiction of the crises that bioarchaeology faces without accurate age estimates. jackes exhaustively reviews all techniques used in evaluating age at death and provides a test of each technique. she maintains that skeletal indicator stages are stages of skeletal change and not direct indicators of chronological age. jackes concludes that statistical techniques cannot take the place of accurate descriptive methods and that any analyses of adult age must employ seriation of adults by many different stage methods scaled by cemental anulations whenever possible. g. r. milner, j. w. wood and j. l. boldsen revisit several questions that are fundamental to the field of paleodemography and at the center of skeletal research in general. the authors present a pragmatic approach to understanding problems of sampling, age and sex estimation, population non-stationarity, heterogeneous frailty and selective mortality. they promote the use of parametric mortality models, maximum likelihood estimation, and other statistical modeling methods as strategies to provide a more reliable estimate of life and death in past populations. bioarchaeology is a highly specialized discipline and students must be well versed in the methods of chemistry and statistics as well as in the discourse of bioethics. this book addresses these concerns by providing in unambiguous detail advanced methods for the analysis of bones and teeth. although many of the methods highlighted in this volume employ destructive techniques, it is evident that students new to graduate research as well as international scholars and senior researchers will find this book a useful tool. indeed, every chapter contains an extensive bibliography as well as practical, reality-based approaches to skeletal research. each author has provided well-written and insightful contributions, with only a handful of errors mainly contained to captions, missing references and a few proofing errors within the text. it is clear that this book will be a mainstay for bioanthropology graduate reading lists and will acquire a welcomed spot on many bioarch-laboratory bookshelves. teri tucker department of anthropology the ohio state university columbus, oh 43210 lipschultz 1997.2 pg4.jpg pg5.jpg pg6.jpg pg7.jpg pg8.jpg eades and desideri 2002.3 52 53 non-metric traits have been studied at our department since the beginning of the 1990’s,1 when two studies were carried out concerning intraand interpopulational analysis of cranial non-metric traits, under the direction of dr. christian simon (gemmerich, 1999; eades, 1996; eades and simon, 1996). in 1997, s. eades became interested in dental non-metric traits during her preparation of a master’s degree at the university of bradford, england (eades, 1997). on her return to the university of geneva in 1998, she undertook a doctoral thesis2 on these traits, bearing on their familial determination (or familiality) and the calculation of interindividual distances. at the same time, j. desideri began her graduate work on an interpopulational comparison of swiss neolithic populations based on their dental morphology (desideri, 2001).3 she is currently undertaking a doctoral thesis4 on the same problematic, but on a wider, european scale. the traits recorded at our laboratory of paleoanthropology include those of the asu system (using the reference casts; turner, nichol and scott, 1991), those of freiburg university (alt, 1997; alt, pichler and vach, unpublished data), when they did not overlap with those of the american system, and a few traits defined by moskona et al. (1997), kraus and furr (1953) and ludwig (1957). interpopulation analysis the first author (s. eades) is examining the dental non-metric traits of a recent skeletal sample, namely, the burlington collection (toronto, canada). the dental casts making up this sample were taken from several hundred families living in burlington between 1952 and 1971 (popovich, 1956). the goal of her thesis is to identify the traits expressing the greatest familiality and to use these traits for univariate and multivariate interindividual comparisons. dental traits are studied by two fields of research: genetics (for the determination of their mode of dental anthropology at the university of geneva suzanne eades* and jocelyne desideri department of anthropology and ecology, laboratory of paleoanthropology, university of geneva *correspondence to: suzanne eades, department of anthropology and ecology, laboratory of paleoanthropology, university of geneva, 12 rue gustave-revilliod, 1227 carouge, geneva, switzerland. email: suzanne.eades@anthro.unige.ch abstract this article presents research currently being conducted in the field of dental anthropology at the department of anthropology and ecology of the university of geneva, switzerland. the first author, s. eades, is carrying out a doctoral thesis on the familiality of dental morphological traits and their use as “familial” indicators in the case of multivariate and univariate analyses of interindividual distances. her methods are based on the modern collection of burlington (ontario), and her results shall be applied to the protohistorical necropolis of kerma (sudan) and the neolithic multiple graves of chamblandes (switzerland). the second author, j. desideri, began her graduate work on an interpopulational comparison of swiss neolithic populations based on their dental morphology. she is currently undertaking a doctoral thesis on the same problem, but tackling the whole of europe. inheritance and their heritability), and archeology (for the application of these results when comparing ancient populations or individuals). the link between the genotype and the phenotype of dental traits appears stronger than for other possibly inherited morphological variants such as non-metric traits of the cranial and post-cranial skeleton. different studies have shown that there is a strong genetic component in the distribution of at least some dental characters, since there is a higher concordance between monozygotic twins than between dizygotic twins (biggerstaff, 1973, 1979; berry, 1978; scott and potter, 1984; kaul et al., 1985; townsend et al., 1988, 1992). given this strong genetic determination, two types of studies have been carried out: the search for the mode of inheritance of these traits, and the calculation of their heritability. we shall see that these approaches did not give forth the results that were hoped for initially. at first, researchers looked for a simple, mendelian, mode of inheritance (see for instance kraus, 1951). deviations from this model were explained by incomplete penetrance and/or variable expressivity. during a second phase, a multifactorial, or polygenic inheritance was proposed (sofaer, 1970; goose and lee, 1971; lee and goose, 1972), based on the model of quasi-continuous variation developed by falconer (1960, 1965). finally, the advent of computers led to the development of new techniques named complex segregation analyses, which test for the presence of major genes within polygenic systems. these were applied to dental non-metric traits by kolakowski et al. (1980) on carabelli’s trait, and by nichol (1989, 1990) on a number of dental traits. in many cases, 52 53 inheritance was found to be polygenic, but influenced by a major gene. as the mode of inheritance could not be established with certainty for several traits, the necessity for more advanced methods of segregation was perceived. as for the calculation of heritabilities, a wide range of figures has been obtained on different traits (see scott and turner, 1997, for a summary). the degree of heritability of a trait is the portion of total variance that is due to genetic variance, as opposed to environmental variance. it does not tell us what portion of an individual’s phenotype can be associated with its heredity or its environment (falconer, 1960, 1965). furthermore, it is chrono-specific, population-specific, and requires a polygenic mode of inheritance, which, as we have seen, is not always the case for dental traits. all these studies have demonstrated that dental traits are genetically determined, whatever the degree of this determination or the mode of inheritance, making them appropriate for infra-population analyses in an archaeological context. these analyses (which are also often based on other types of non-metric traits) are of three types: • the study of residence patterns (see for instance lane, 1977; lane and sublett, 1972; spence, 1974a,b), • the development of microchronologies in an archeological context (see konigsberg, 1986, 1987, 1990; crubézy, 1991), • the identification of related individuals or lineages. the last type of study is the subject of s. eades’ doctoral thesis. although such studies have been carried out before (see for instance alt, 1997, alt et al., 1995, 1997; crubézy, 1991; howell et al., 1996; corrucini and shimada, 2002), they have rarely been based on individuals of known parentage (but see eades, 1997 and gemmerich, 1999). based on data recorded on the burlington collection (parents and children), s. eades has estimated the familiality of 107 dental traits derived from concordance analysis (ludwig, 1957). those traits which were the most concordant in their expression within families, as well as their most useful format for such purposes (dichotomous, graded or dichotomized), were identified. different univariate and multivariate analyses were carried out on these traits and on a selection of families with well-preserved dentitions. the multivariate analyses in particular gave forth some very encouraging results, which she would like to publish by next year. their application in the field of skeletal archeology seems possible; obviously, dental morphological traits are not as powerful as dna analysis, but it seems that in the case of clear groupings of graves or individuals (that is, when the presence of family units is suspected) over a restricted timespan, it is possible to indicate whether specific individuals are related or not. s. eades is currently applying these methods to the neolithic necropolis of kerma (sudan, bonnet, 1990, 2000), where it is suspected that the multiple burials with sacrificed individuals represent genetically linked family members. she shall also study multiple burials in stone cists from the swiss neolithic necropolis of chamblandes (moinat and simon, 1986). intrapopulation analysis the second author (j. desideri) is studying the bell beaker phenomenon. this period is primarily known as a pottery style found over most of europe at the end of the neolithic. this entity differs from previous archaeological cultures by its material culture, its funerary rituals and its diffusion processes. the bell beaker culture has been studied extensively,5 and research based on its associated artifacts has indicated either continuity or rupture in the peopling. however, there have been very few studies of the physical anthropology of the individuals making up this civilization. the biometrician r. menk (1979, 1981) proposed a synthesis of the bell beaker complex on an european scale, based on multivariate craniometric methods. he tried to isolate the morphological characteristics of these individuals in order to demonstrate the existence of a bell beaker “humanity” associated with its various cultural expressions and to deduce its origins and impact in different regions of europe. according to menk, this bell beaker “humanity” possessed a very different morphology to that of the local substrate. in the nuclear zone (central germany, moravia, bohemia and poland), the morphology is homogeneous; however, in peripheral areas, the bell beaker physical type becomes minoritarian and decreases as a function of the distance from the central zone. j. desideri’s interest during her graduate work (desideri, 2001) was to clarify the biological relationships between the local, middle and late neolithic populations, and the later, culturally dissimilar bell beaker populations in western switzerland, by studying dental non-metric traits. she studied ten samples dating from the middle neolithic to the early bronze age (table 1). craniometric analyses (menk, 1979, 1981) and the evolution of funerary rituals (bocksberger, 1976, 1978; gallay, 1978, 1998) both pointed to a major event taking place around 2600 bc with the arrival of the bell beaker culture in western switzerland. at this time, late neolithic dolmens were emptied and bell beaker remains were deposited in their place (m vi dolmen), furthermore, a new type of cist inhumation appeared (m xi dolmen). dental traits were particularly appropriate to this purpose, as the crania recovered in the different dolmens are particularly fragmented, making for low sample numbers and insufficient population representation. in total, only five skulls could be measured; they were very different in their morphology from those preceding and following them chronologically, giving credence to population dental anthropology at geneva 54 55s. eades and j. desideri movement theories. the analyses, based on 61 uncorrelated traits after preliminary standard manipulations,6 made it possible to draw a picture of the different populations, and particularly the circumstances which led to the emergence of the bell beaker culture in western switzerland. during the neolithic, the populations are homogeneous and morphologically similar, without major external influences. this is not the case for the bell beaker culture, as these populations are not only very different from the preceding populations, but also from one another. as for the bronze age, two situations co-exist: some groups possess a neolithic morphology, whereas others are clearly different from the anterior groups. the analyses (multidimensional scaling and hierarchical cluster analysis) based on the late neolithic and bell beaker groups made it possible to propose three interpretative models which could explain the differences encountered during the bell beaker culture (fig. 1). the models are based on the fact that the bell beaker dental remains were very different from those of preceding populations. • the arrival of individuals from another population in western switzerland is possible. they may have completely replaced the preceding populations or, on the other hand, have been integrated into the local communities. these individuals may have belonged to two different groups, as the two bell beaker dolmens are quite distant from one another on these figures. • it is possible that the new funerary rituals practiced by the members of this group may have played a major role, as bell beaker burials inside dolmens were restricted to a dozen individuals, whereas earlier necropoli (cist graves or similar dolmens) contained between 40 and 100 individuals. we may be looking at frequencies of a subset of the total population at this time (such as members of a single family or a social elite), and not population frequencies sensu stricto. • the two preceding models are not exclusive. it is possible that these remains represent a subset of the table 1. presentation of the ten samples studied by j. desideri for her graduate work (desideri, 2001) dating site type of inhumation number of burials references middle neolithic : 45003200 bc barmaz i (canton of valais) chamblandes-type cist, mostly single burials 41 graves, 49 subjects sauter, 1949, 1950, 1951; honegger, 1996 barmaz ii (canton of valais) 21 graves,22 subjects sauter, 1949, 1950, 1951 chamblandes (canton of vaud) chamblandes-type cist, mostly collective burials 70 graves, 116 subjects moinat and simon, 1986 corseaux (canton of vaud) 27 graves,60 subjects kramar et al., 1978; baudais and kramar, 1990 late neolithic : 3200-2600 bc dolmen m xii sion petit-chasseur (canton of valais) triangular-based dolmens about 80 subjects favre and mottet, 1990, 1995; eades, 1996 dolmen m vi sion petit-chasseur (canton of valais) about 40 subjects kramar, 1977; gallay, 1986; gallay and chaix, 1984; bocksberger, 1976, 1978 bell beaker culture : 2600-2200 bc dolmen m vi sion petit-chasseur (canton of valais) triangular-based dolmens about 10 subjects kramar, 1977; gallay, 1986; gallay and chaix, 1984; bocksberger, 1976, 1978 dolmen m xi sion petit-chasseur (canton of valais) lateral-entry dolmens about 10 subjects gallay, 1986; gallay and chaix, 1984; bocksberger, 1976, 1978; claivazcaruzzo, 1975 early bronze age : 2200-1550 bc sion petit-chasseur (canton of valais) peripheral cists and graves about 10 subjects bocksberger, 1976, 1978 barmaz i (canton of valais) single graves about 15 subjects honegger, 1996 54 55 total population, including some individuals of foreign extraction, having arrived in western switzerland for trade or as specialized craftworkers, and having been integrated into the community. this would explain the extent of the morphological differences as well as the re-use of the late neolithic dolmens during the bell beaker period and the adoption of a new material culture around this time. in summary, clear-cut differences were detected between middle neolithic and bell beaker dental remains. the reasons behind these differences are, however, difficult to explain fully. for the moment, an adequate way of describing the appearance of the bell beaker culture in western switzerland is not “rupture”, nor “continuity”, but simply “difference”. these results led j. desideri to extend her research to the rest of europe for her doctoral thesis. she shall base her research on the different geographical domains (fig. 2) defined by m. besse’s (2001) study of bell beaker common ware,7 by compiling a corpus including pre-bell beaker (late neolithic), bell beaker and post-bell beaker (bronze age) individuals. the eastern domain shall be ��������� � ��������� � � ��� ���� ���� ���� �� �� �� � � ��� ��� ���         � � �� �� �� �� ����������� �������� ������ � ��� ������ � �� ������ � ������ �� ������ � �� ������ � ��         ������ � �� ������ � ������ �� ����������� �������� ������ � ��� ������ � �� ������ � �� fig. 1. cluster analysis (euclidean distance, upgma method), above, and multidimensional scaling (with a stress value of 5%), below, representing the position of different middle neolithic (symbolised by a circle), late neolithic (triangles) and bell beaker (lozenges) populations in western switzerland, based on the observation of 61 dental non-metric traits. dental anthropology at geneva 56 57s. eades and j. desideri represented by a series of subjects from sites located mostly in the czech republic, but also from hungary, austria and poland. the southern domain will cover funerary assemblages from switzerland, northern italy and france. finally, the northern domain shall include individuals from belgium, the netherlands, and part of germany. j. desideri shall try to answer certain questions that should make it possible to reconstruct the history of these populations before, during, and after the bell beaker culture. she shall more specifically try to determine whether this culture is characterized by a rupture or a continuity of the local population, and whether it is responsible for the emergence of the early bronze age. by confronting her results with data from other archaeological and anthropological studies, she hopes to understand the modalities which made possible the emergence of such a widespread phenomenon. conclusion so far, work on dental non-metric traits carried out at the department of anthropology and ecology of geneva university has proved promising. hypotheses concerning the population of western switzerland during the late neolithic have been arrived at, and data collected on individuals of known family relationships is currently being exploited. at the moment, little work is being carried out in europe on dental non-metric traits, and the two authors have few opportunities to confront their results and methods with fellow researchers in this domain. we hope that this brief presentation in the papers of the daa will be of interest to dental anthropologists working in america or elsewhere; any comments or suggestions concerning these two research subjects will be highly appreciated.the authors would like to thank dr. christiane kramar for her help in writing this article. acknowledgements suzanne eades would like to thank the fonds national suisse de la recherche scientifique, the fondation ernst et lucie schmidheiny and the société de physique et d’histoire naturelle de genève for their crucial financial support. her study was made possible by use of material from the burlington growth center, faculty of dentistry, university of toronto, which was supported by funds provided by grant (1) (n° 605-7299) national health grant (canada), (data collection); (2) province of ontario grant pr 33 (duplicating) and (3) the varsity fund (for housing and collection). jocelyne desideri would like to thank the académie suisse des sciences naturelles, the société suisse d’anthropologie and the department of 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wiley liss, p 13-31. footnotes 1 with the exception of a pioneering work by h. muller in 1977. 2 under the direction of profs. andré langaney and alain gallay from this department. 3 under the direction of dr. christian simon, lecturer at the department of anthropology, who unfortunately passed away at the beginning of 2000, and prof. alain gallay. 4 under the direction of prof. andré langaney, director, and marie besse, assistant professor, both at the department of anthropology of geneva university. 5 sangmeister, 1963; gimbutas, 1970; lanting and van der waals, 1976; gallay, 1978; 1998; guilaine, 1998; besse, 2001. 6 elimination of invariant expressions, of sexually dimorphic traits, fusion of bilaterally expressed traits, estimation of trait population incidences on mesial teeth by turner’s (1985) expression count. 7 besse defined three geographic areas in continental europe based on the study of cultural differences according to the bell beaker common ware (besse 2001): a northern, a southern and an eastern domain. dental anthropology at geneva pinhasi 1998.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg pg7.jpg pg8.jpg pg9.jpg pg10.jpg harris 2006.3 74 dr. stefan’s interesting description of two archeological cases with severely malposed premolars (dental anthropology 2006;19(3):70-73) prompted me to review two comparable cases i have encountered. i present these here in hopes that their description will stimulate discussion from the readership. case 1 figure 1 shows an occlusal view of the mandibular dental arch of a 24-year-old american black male. all 16 permanent mandibular teeth are erupted into functional occlusion, and, as shown in this figure, there is appreciable anterior dental crowding. the notable feature, of course, is the buccolingual juxtaposition of the left first and second premolars, where the second premolar is erupted ectopically to the lingual (with ~40° distolingual rotation) and the first premolar is rotated with the lingual aspect ~40° to the mesial. the canine is ectopically positioned to the labial in the corresponding right quadrant, but the two right premolars are arranged normally in the midarch. there is good gingival height around both ectopic premolars, with normal crown-root ratios as viewed from radiographs. premolar alignment is normal in the maxillary arch. case 2 this is a 14-year-old american white girl. figure 2 shows the buccal-lingual arrangement of her maxillary right premolars. the second premolar is displaced to the lingual with mesial rotation of the tooth’s lingual aspect. the first premolar is deviated less transversely, but the lingual aspect is rotated ~80° to the lingual (lingual rotation of the second premolar is ~60°). gingival contours are healthy around all teeth. premolar arrangement is normal in the other three quadrants. all 32 permanent teeth are present on x-ray, though the third molars have not yet emerged. perspective it is tenuous to speculate on the etiology of these rotations and displacements just from examination of the completed dentition because several different factors may have been contributory. one possibility, of course, is that the premolars’ tooth crypts formed in the commentary: rotated premolars edward f. harris* department of orthodontics and department of pediatric dentistry, university of tennessee, memphis wrong positions and thse teeth’s erupted malpositions reflect this developmental anomaly. figure 3 shows a panoramic radiograph of a young boy with such a problem. instead of the premolar crypts being located in the root bifurcations of the primary molars, the crypts of both the first and second premolar are beneath (apical to) the primary first molar. in this boy, the same malposition occurs in all four quadrants rather than just one quadrant as seen in the four older cases presented by dr. stefan and myself. alternatively, the permanent first molar (that emerges well before the premolars) could be the culprit. if this molar ’s eruptive path were deflected to the mesial, it would have compromised the arch space available for normal premolar eruption. with inadequate space, the premolars would remain trapped within the bone, or would have erupted along whatever pathway of least resistance presented itself. one can speculate that compromised space forced the premolars into the odd positions seen in the cases presented here. this situation occasionally occurs in the maxilla because of the upper molar ’s normal mesial-occlusal eruptive trajectory (e.g., van der linden and duterloo, 1976; duterloo, 1991). it is much less common in the mandible because the lower molar normally has an essentially vertical path of eruption. figure 4 shows the panoramic radiograph of a case where the maxillary first molars are mesially inclined and are actively lysing through the distal root of the primary second molars. in contrast, the mandibular first molars have erupted normally, distal to the primary second molars. several clinicians have reported on the occlusal consequences of first-molar ectopia, notably in the maxilla (e.g., kurol and bjerklin, 1986; bjerklin, 1994; barberia-leache et al., 2005). the scenario would be that the early-erupting first molar erupts in to the space that should be held by the primary second molar, leading to this primary tooth’s premature loss, and the space for the normal emergence of the premolar is compromised, leading to failure to erupt (impaction) or, conceivably as seen in *correspondence to: edward f. harris, department of orthodontics, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu 75 fig. 1. case of a young adult american black male with buccal-lingual juxtaposition of the mandibular left premolars. top: intraoral photograph of the mandibular arch, showing the ectopic premolars and appreciable anterior crowding. bottom: occlusal view of the same subject’s dental cast. fig. 2. case of an adolescent american white female with buccal-lingual juxtaposition of the maxillary right premolars. top: intraoral photograph of the maxillary arch. aside from the ectopic premolars in the right quadrant, there is little crowding. the absence of space mesial to the first or second molar on the right illustrates the effect of mesial drift. bottom: occlusal view of the same subject’s dental cast. commentary: rotated premolars figures 1 and 2, ectopia of one or both premolars in a quadrant. another possibility is caries: indeed, historically, caries was the greatest single cause of malocclusion (e.g., weinberger, 1926). the two primary molars in a quadrant can be viewed as space holders for the lateremerging premolars. if one or both primary molar is lost prematurely because of caries, the permanent first molar will drift forward, diminishing the space available for normal eruption of one or both premolars. an example of an impacted second premolar is shown in figure 5; here the failure of eruption was due to caries and premature loss of the primary second molar, followed by mesial drift of the permanent first molar before the second premolar could erupt. contemporary dentists have a variety of appliances that can be used to preserve the arch space of an extracted primary tooth (e.g., ngan et al., 1999; choonara, 2005), but, of course, this was not an option in the past—when caries also was a more prevalent health problem. 76 a quick review of the literature shows that premature loss of a primary tooth affects the eruption tempo of its successor, but the effects reported are contradictory, some stating that premature loss accelerates eruption of the replacement tooth, others that loss delays eruption (reviewed, e.g., by ronnerman, 1977, loevy, 1989). fanning (1962), though often overlooked, was among the first to make sense of the situation, and my elaboration of her findings is this: when a primary tooth is lost at an early age, the supporting alveolar bone has plenty of time to heal and remodel (often atrophying to a narrow ridge) and the successor ’s root is too immature to initiate eruption (though the true “initator” of eruption is poorly understood). eruption of the successor is delayed in such cases, which increases the opportunity and extent of drift of teeth adjacent to the extraction site (e.g., ronnerman, 1977; ronnerman and thilander, 1978; northway, 2000). in contrast, if the primary tooth is lost at an older age, the successor is more mature and closer to its normal eruption age, so the alveolar bone remains less remodeled and more cancellous (boyne, 1995; diedrich and wehrbein, 1997; hasler et al., 1997), and eruption is hastened. when the successor erupts soon into the extraction space, there is little opportunity for drift of the adjacent teeth, thus enhancing chances of normal occlusal position. although uncommon, it is useful to mention pathological conditions that can retard exfoliation (of the primary tooth) and/or eruption (of the succedaneous tooth). an odontoma—a generally benign developmental hamartomatous lesion often coronal to an unerupted tooth—consists of tissues that resist tooth eruption as well as the normal migration fig. 4. panoramic radiograph of a child in whom the maxillary permanent first molars have accentuated mesial crown tipping, with eruptive paths that have lysed the distal roots of the primary second molars. this leads to premature loss of the primary molars, followed by mesial drift of the permanent molars that, in turn, reduces space in the midarch that precludes normal eruption of the second premolars. mesial inclination of the permanent first molars is appreciably more common in the maxilla. fig. 5. radiograph of an adolescent in whom the primary second molar exfoliated prematurely due to caries. without dental intervention to hold the space, the permanent molars drifted mesially, resulting in the second premolar being impacted because its eruptive path was occluded by the earlier-emerging adjacent teeth. fig. 3. panoramic radiograph of young boy with ectopic development of the second premolars in each quadrant. instead of the second premolar crypts forming in the bifurcation of the primary second molar ’s roots, as is normal, they are ectopically malpositioned apical to the primary first molars. malpositions of the succedaneous tooth crypts is one possible cause of the maloccluded premolars seen in cases 1 and 2, though here—with all four quadrants involved—the problem probably is systemic rather than local. e. f. harris 77 of erupted teeth. some odontomas form enamel and dentinal structures that look like miniature teeth (“toothlets”), but others leave no readily-discernible skeletal evidence of their existence. morning (1980) reviewed tooth impactions secondary to odontomas (also see amado cuesta et al., 2003; tomizawa et al., 2005). the case reported by kupietzky and coworkers (2003) is relevant here because it details the ectopic displacement of a second molar consequent to an odontoma. in a similar vein, molecular biologists have discovered genes that influence tooth eruption, notably, mutant alleles that interfere with the normal lysis of bone ahead of an erupting tooth, which can lead to impaction (e.g., tiffee et al., 1999; nishino et al., 2001; ida-yonemochi et al., 2004). the commonality of these various scenarios involves the similarity of developmental timing of the first and second premolars (and canine) in each quadrant. these three teeth erupt during what van der linden and duterloo (1976) term the “second transition”— roughly 10 to 12 years of age (fig. 6). hurme (1949, 1951, 1957) published syntheses of eruption studies, and his classic works are still among the most common citations on the subject. hurme (1951) found that, modally, the second premolar erupts roughly 9 months later than the first premolar, though there is some inter-individual variation (kent et al., 1978; smith ad garn, 1987; diamanti and townsend, 2003). liversidge recently (2003) has collated the extensive literature from the 20th century. the data (based on various collection strategies and various statistical methods) show that the second premolars characteristically emerge later than the first, but, again, these averages hide the considerable variability among individuals. inspection of the four cases reported by dr. stefan and myself show that, in each instance, the second premolar ’s position is more aberrant than the first—and this is consistent with the later-emerging second premolar moving into a more-constrained space (because, statistically, the first premolar probably emerged slightly earlier and commandeered space for itself). it may be relevant too that in all four cases presented by dr. stefan and myself, the malposed premolars are restricted to one quadrant—suggesting that the etiology generally is anatomically localized rather than systemic. importantly, modal eruption ages can camouflage the variability in eruption sequences, though published reports of just the former are far more common. sato and parsons (1990) documented the appreciable variation seen in eruption sequences, particularly when the subjects can be followed longitudinally. the first premolar emerges ahead of the second (p1→p2) in most children (80% in maxilla; 96% in mandible), which agrees with the findings of smith and garn (1987) who, using cross-sectional data, found p1→p2 in about 90% of their children. diamanti and townsend (2003) also assessed data cross-sectionally, and found somewhat higher frequencies for p1→p2, about 97% in both arches. the relevant point here is that the data agree that the first premolar is quite likely to emerge before the second, thus putting p2 at greater risk for impaction or malposition—and this is what is seen in all four of the cases reviewed here. these comments do not detract from dr. stefan’s presentation. instead, they are meant to emphasize the dynamic sequence of events that, gone awry, can lead to the observed malplacements of later-forming teeth. indeed, in addition to the broad criteria developed by butler (1939) and dahlberg (1945), a premolar field can be assessed by a variety of other measures, such as crown and root size and morphology, and similarities in formation, eruption, and emergence times and sequences. acknowledgements i extend my thanks to dr. robert turner and dr. jerome burr who provided the orthodontic records of my case 1 and case 2, respectively. dr. betsy barcroft provided the records for figure 3, and dr. woodrow powell provided the records for figure 4. b b b b b b b b b b b b b b j j j j j j j j j j j j j j i1 i2 c p1 p2 m1 m2 i1 i2 c p1 p2 m1 m2 5 6 7 8 9 10 11 12 13 c h ro n o lo g ic a l a g e ( y e a rs ) b boys j girls maxilla mandible fig. 6. graph of median emergence ages in caucasions (data from hurme, 1951). data are presented by sex, with gingival emergence being precocious in girls. the key issue is the similarity in emergence ages for the two premolars in a quadrant (i.e., the pairs of symbols connected by lines); while the first premolar is characteristically developmentally advanced over the second, the times are so similar that these teeth are obliged to compete for limited arch space. commentary: rotated premolars 78 literature cited amado cuesta s, gargallo albiol j, berini aytes l, gay escoda c. 2003. review of 61 cases of odontoma; presentation of an erupted complex odontoma. med oral 8:366-373. barberia-leache e, suarez-clua mc, saavedraontiveros d. 2005. ectopic eruption of the maxillary first permanent molar: characteristics and occurrence in growing children. angle orthod 75:610-615. bjerklin k. 1994. ectopic eruption of the maxillary first permanent molar. an epidemiological, familial, aetiological and longitudinal clinical study. swed dent j suppl 100:1-66. boyne pj. 1995. use of htr in tooth extraction sockets to maintain alveolar ridge height and increase concentration of alveolar bone matrix. gen dent 43:470-473. butler pm. 1939. studies of the mammalian dentition: differentiation of the post-canine dentition. proc zool soc lond b109:1-36. choonara sa. 2005. orthodontic space maintenance— a review of current concepts and methods. sadj 60:113, 115-117. dahlberg aa. 1945. the changing dentition of man. j am dent assoc 32:676-690. diamanti j, townsend gc. 2003. new standards for permanent tooth emergence in australian children. aust dent j 48:39-42. diedrich p, wehrbein h. 1997. orthodontic retraction into recent and healed extraction sites: a histologic study. j orofac orthop 58:90-99. duterloo hs. 1991. an atlas of dentition in childhood: orthodontic diagnosis and panoramic radiology. london: wolfe publishing ltd. fanning ea. 1962. effect of extraction of deciduous molars on the formation and eruption of their successors. angle orthod 32:44-53. hasler r, schmid g, ingervall b, gebauer u. 1997. a clinical comparison of the rate of maxillary canine retraction into healed and recent extraction sites—a pilot study. eur j orthod 19:711-719. hurme vo. 1949. ranges of normalcy in the eruption of permanent teeth. j dent child 16:11-15. hurme vo. 1951. standards of variation in the eruption of the first six permanent teeth. child devel 37:800803. hurme vo. 1957. the human dentition in forensic medicine: symposium. j forensic sci 2:377-388. ida-yonemochi h, ishibashi o, sakai h, saku t. 2004. recruitment of osteoclasts in the mandible of osteopetrotic (op/op) mice. eur j oral sci 112:148155. kent rl jr, reed rb, moorrees cf. 1978. associations in emergence age among permanent teeth. am j phys anthropol 48:131-142. kupietzky a, flaitz cm, zeltser r. 2003. eruption of a severely displaced second permanent molar following surgical removal of an odontoma. pediatr dent 25:378-382. kurol j, bjerklin k. 1986. ectopic eruption of maxillary first permanent molars: a review. asdc j dent child 53:209-214. van der linden fpgm, duterloo hs. 1976. development of the human dentition: an atlas. hagerstown, md: harper and row, publishers. liversidge h. 2003. variation in modern human dental development. in: thompson jl, krovitz ge, nelson aj, eds. patterns of growth and development in the genus homo. cambridge: cambridge university press, p 73-113. loevy ht. 1989. the effect of primary tooth extraction on the eruption of succedaneous premolars. j am dent assoc 118:715-718. morning p. 1980. impacted teeth in relation to odontomas. int j oral surg 9:81-91. ngan p, alkire rg, fields h jr. 1999. management of space problems in the primary and mixed dentitions. j am dent assoc 130:1330-1339. nishino i, amizuka n, ozawa h. 2001. histochemical examination of osteoblastic activity in op/op mice with or without injection of recombinant m-csf. j bone miner metab 19:267-276. northway wm. 2000. the not-so-harmless maxillary primary first molar extraction. j am dent assoc 131:1711-1720. ronnerman a. 1977. the effect of early loss of primary molars on tooth eruption and space conditions: a longitudinal study. acta odontol scand 35:229-239. ronnerman a, thilander b. 1978. facial and dental arch morphology in children with and without early loss of deciduous molars. am j orthod 73:47-58. sato s, parsons p. 1990. eruption of permanent teeth: a color atlas. st louis: ishiyaku euroamerica, inc. smith bh, garn sm. 1987. polymorphisms in eruption sequence of permanent teeth in american children. am j phys anthropol 74:289-303. tiffee jc, xing l, nilsson s, boyce bf. 1999. dental abnormalities associated with failure of tooth eruption in src knockout and op/op mice. calcif tissue int 65:53-58. tomizawa m, otsuka y, noda t. 2005. clinical observations of odontomas in japanese children: 39 cases including one recurrent case. int j paediatr dent 15:37-43. weinberger bw. 1926. orthodontics: an historical review of its origin and evolution. st. louis: cv mosby company. e. f. harris 19 dental anthropology 2018 │ volume 31 │ issue 01 dante’s peak and volcano (1997), armageddon and deep impact (1998) – the universe has an odd tendency toward synchronicity. in 2017, a quarter of a century after the publication of the much photocopied turner et al. (1991), two different manuals have been published that provide further guidance on how to score human dental morphology – scott and irish’s “human tooth crown and root morphology” (cambridge), and edgar’s “dental morphology for anthropology” (routledge). as lab manuals, both books have a similar structure, with the trait-by-trait guide providing the bulk of the pages. the “bookends” differ somewhat. in scott and irish, the introductory sections discuss the history of trait scoring and the asudas, followed by a basic introduction to dental anatomy and terminology. the anatomy section, in particular, is absolutely essential for those unfamiliar with dentition. without it, using the scoring standards would be difficult. as this comprises only the first nine pages it is not an exhaustive discussion. after 250 pages of the manual itself, scott and irish concludes with a ten page chapter on scoring concerns and analytical details followed by an appendix of comparative data from the turner archives. these data are invaluable and should not be overlooked in assessing the merits of this book. scott’s efforts to organize these archives should be commended and will greatly impact the field in the future. a wellknown standard analytical complications are also summarized: sexual dimorphism, inter-trait correlation, breakpoints and tabulation methods, wear and age effects, observer error, and a short discussion of the mmd. a sample data sheet is also provided. edgar’s bookends have a different focus. instead of discussing the history of the field and dental anatomy, edgar details distinct problem orientations at different scales of analysis. challenges of trait scoring are outlined, but with less detail than in scott and irish. however, edgar provides a more thorough overview of analytical methods, which results from her emphasis on global through individual scales of analysis that require more than mmd statistics. after 120 pages of the trait manual, edgar’s book closes with a sample data sheet, reference pages, and a glossary. neither book is exhaustive in its treatment of the topics presented in their introductory and closing sections, but these overviews do serve to point the reader in the right direction. although required for context, few readers will buy the books for these extras. the value of both is in the lab manual section and its utility for trait scoring. both use a standard structure in their tour of traits. edgar adopts a grid system with a “two pages per trait” format that crosses the fold. for each trait the following is provided: trait name, asudas plaque (if applicable), a visible guide indicating where on the tooth to observe/score the trait, and a grade-by-grade description and visualization of the different scores. for most traits, each expression grade is visually represented by a drawing with two or more images of actual teeth from varying angles. the asudas plaque is not shown for each trait. the use of a grid makes sense for the purposes of standardization, but with two rows of five boxes, some trait presentations look odd due to the large amount of blank space on the page. however, the attempt to standardize the presentation is commendable and was clearly designed with an eye toward direct use in data collection. my main critique of the edgar volume is that the images should be larger, and the drawings are really the best illustrations of the morphological variation presented. scott and irish use a different approach. individual traits receive differing levels of attention rather than a standard two-page treatment, however, a standard set of information is presented for each character: teeth observed, key tooth, synonyms, description, classification (the grades), breakpoint, potential observation/ scoring complications, geographic variation, and a selected bibliography. for those traits with asudas plaques, a large image is presented with arrows pointing to the key aspect of variation. i note that the plaques are shown larger than 1:1 scale in some cases. the main difference between the two books is how each defines the goal of a lab manual. edgar contains less supplemental text and is focused on presenting basic expression grade descriptions and a visual example of each grade. scott and irish uses images of asudas plaques to visualize potential ranges of expression, and instead uses images of teeth as examples of specific grades and to highlight potential challenges or present particularly rare examples. my main suggestion for scott and irish is to move each grade description and associated reference plaque image to the same page to ensure that there are no orphaned grade descriptions. the trait lists in each book are similar but not idenbook review human tooth crown and root morphology. by g. richard scott and joel d. irish. cambridge: cambridge university press. 2017. 332 pp., $49.97 (paperback). isbn 978-1-10748073-5. dental morphology for anthropology: an illustrated manual. by heather j.h. edgar with illustrations by e. susanne daly. new york: routledge. 2017. 184 pp., $28.37 (paperback). isbn 978-1-62958512-3. 20 dental anthropology 2018 │ volume 31 │ issue 01 tical. both books focus on the key list of asudas crown features, with deciduous traits largely omitted. scott and irish provide descriptions of root features, while edgar sets aside a two-page chapter with basic descriptions and a summary table of root variants. edgar discusses uncommon traits such as lateral incisor mesial bending, tri-cusped maxillary premolars (curiously omitted by scott and irish despite being in turner et al. (1991) where it is listed as extremely rare, edgar provides two images), supernumerary teeth, and elongated mandibular premolars. scott and irish provide discussion of other traits such as marginal ridge tubercles of the maxillary molars and rare traits such as bifurcated hypocone and lateral incisor variants (not mesial bending) as well as asudas features such as rocker jaw, torsomolar angle, and palatine and mandibular tori. in this sense, scott and irish remain more faithful to the original turner et al. article (tricusped premolars, notwithstanding). neither delves into more obscure anatomy too deeply. this makes sense for scott and irish who are more concerned with broad-scale relationships than with random anomalies that may indicate familial relationships. scott and irish paginate the traits within the table of contents and also number them sequentially within the text (each page has a running page number with the trait number near the top of the page). edgar’s book does not include a pagination in the table of contents, which makes it more difficult to easily find the information. in terms of production value, the page size and paper quality are roughly the same (scott and irish is slightly larger than the standard 6x9 inch page size). scott and irish is spiral bound, which makes it easy to use because all pages open completely and the book can lay flat on the table. this is important when collecting data. edgar’s book is traditionally bound with hard boards, which makes it more difficult to see the pages without breaking the spine. the picture quality is also sharper in scott and irish’s book. the figures are almost all photographs, whereas edgar’s book includes a mix of drawings and photographs. an important difference here is the size of the images. scott and irish use large format images (roughly half page) that are excellently reproduced by cambridge. some of edgar’s images are small and difficult to see as routledge’s image reproductions were often grainy and less than optimal. using hillson-fitzgerald calipers i measured the images provided for incisor double shoveling and came up with 126.68 x 84.88 mm for scott and irish and 21.91 x 20.26 mm for edgar. i initially thought edgar was trying to show the features at a 1:1 scale, but this was not the case. the sixty-four thousand dollar question – do these manuals replace the turner et al. article? probably. but there are some important considerations, and these relate to the trait descriptions provided. neither are exactly faithful to the terminology from the 1991 article, which begs the question of whether simply copying the same trait descriptions would violate copyright (i suspect the word count is beyond fair use). this is somewhat unfortunate because there is the potential for observer error to occur. an as example, for cusp 6 edgar specifies numerically how much larger the cusp should be for a grade of 5 (a useful addition, though absent from the turner et al. article). scott and irish jettison the 3.5 grade for hypocone (but not metacone), causing a shift in the scores for those that used turner et al. (a minor point really), but have other slight variances in their grade descriptions (e.g. carabelli’s cusp; collapsing the lower premolar trait into a simple cusp count seems logical). the grade descriptions for tuberculum dentale differ more significantly, as do those of edgar (both omit the 5grade, among other wording differences). in the case of winging, scott and irish use a completely different system that will require future researchers to be mindful of what they mean when they state that “data were scored using asudas standards.” it is, of course, easy enough to convert these scores in most cases, but the publication of these books does require us to be more exact in our methodology write-ups. the important point is that the joint publication of these books reflects continued researcher interest in human dental morphology. both books help break the sense of stasis the ubiquity of the turner et al. article created. this was not the intent of its architects, who always intended for trait lists to expand and definitions to be modified and improved, with problematic aspects of the asudas discarded. this really is an exciting time to be a dental anthropologist, and both books will help propel the field in new and exciting directions. both deserve a space on the shelves of dental anthropologists, along with well-used copies of the turner et al. chapter. reference turner c. g., nichol c. r., and scott g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, and larsen cs, editors. advances in dental anthropology (pp. 13-31). new york: wiley-liss. christopher stojanowski school of human evolution and social change arizona state university hanson and miller 1997.3 pg9.jpg pg10.jpg pg11.jpg pg12.jpg harris 2003.4 84 85 if one measures the conventional mesiodistal and buccolingual crown diameters of the 32 permanent teeth in the human dentition, there are 64 variables, which is comparable to an extensive battery of craniometrics or anthropometrics (e.g., davenport, 1927; martin, 1928). one might suppose that there is a lot of statistical information—several axes of variation—in the odontometrics based on tooth types, side, arcade, a tooth’s position in its morphogenetic field, sex, race, and so on. however, the morphological and statistical redundancy among tooth types has long been recognized, and this redundancy sharply diminishes the information content of batteries of crown dimensions. bateson (1894) included teeth in his anatomic examples of meristic series that included phalanges, vertebrae, and ribs. this phenomenon of multiple analogous skeletodental units that develop clinally along a growth axis also is termed polyisomerism (gregory, 1934). the supposition is that the shared morphologies are controlled by common control mechanisms (genes, gene products), but verification has only recently been provided (e.g., yamaguchi, 1997; green, 2002). weiss (1990), jernvall (2000; jernvall and jung, 2000; jernvall and thesleff, 2000), and others suggest that polyisomerism is a conservative, efficient mechanism for increasing (or, occasionally, decreasing) the anatomic units, which is more obvious phylogenetically, but occurs ontogenetically as well. the “several” where’s the variation? variance components in tooth sizes of the permanent dentition edward f. harris* department of orthodontics, the health science center, university of tennessee 38163 *correspondence to: edward f. harris, department of orthodontics, the health science center, university of tennessee, memphis 38163. e-mail eharris@utmem.edu a version of this paper was presented at the annual meeting of the american association of physical anthropologists, tempe, az, 2003. abstract studies have shown that there are only a few canonical axes of tooth size variation in the permanent dentition. despite the numerous measurements that might be taken (e.g., crown length and breadth of 32 teeth = 64 variables), most of the canonical structure is explained by 3 or 4 overarching axes of variation. this study used maximum likelihood components of variance analysis to determine where the major sources of statistical variation are among the crown dimensions in the permanent dentition. mesiodistal and buccolingual crown dimensions were measured on all permanent teeth (excluding m3s and averaging sides) in 100 american whites and 100 american blacks, evenly divided by sex. the sas program varcomp estimated the sources of variation across 7 aspects of the dentition, namely race, sex, arcade, tooth (incisor, canine, premolar, molar), position (mesial, distal), dimension (md, bl), and a residual term. most variation is shared; residual variance was just 21.8% of the total. considering the six components of shared variance, the greatest (82.8%) was due to tooth type (i, c, p, m). in contrast, only 4.9% was attributable to the black-white race difference, which confirms results of other biological data that the preponderance of variation is within groups, not among them. more striking is the lack of variation between males and females (1.2%)—confirming the insensitivity of tooth crown dimensions for forensic purposes. very little shared variance (0.6%) was due to tooth position, indicating that the mesial “pole” tooth that is metrically and morphologically more stable does not possess much more informational content statistically. whether the tooth was maxillary or mandibular accounted for 6.9%. in a practical sense, the large variance due to tooth type implies that dental anthropologists commonly will want to include variables from all tooth types (i, c, p, m) rather than multiple measurements within a tooth type, since tooth type is the canonical axis of variation. dental anthropology 2003;16(3):84-94. canonical axes of variation expected from a battery of tooth dimensions do not actually occur because tooth crown dimensions are invariably positively intercorrelated (e.g., moorrees and reed, 1964; potter et al., 1968; henderson, 1975; townsend, 1976; harris and bailit, 1988). genetic covariance among continuous-scale variates like crown dimensions arises from pleiotropic effects of the contributing genes (e.g., falconer, 1989). indeed, the principal theme of butler’s seminal studies of morphogenetic fields (1939, 1956, 2001) is the developmental dependencies (covariance) of tooth morphologies and dimensions of teeth within the three major fields in mammals, namely incisors, canines, and postcanine tooth types. the consequences for the dental anthropologist are that much of the informational content of many tooth crown dimensions are statistically redundant. measuring more teeth or measuring more dimensions of the same teeth does not proportionately increase 84 85 the researcher’s ability to discriminate between sexes, or populations, or races, or species. falk and corruccini (1982) have shown this quite simply: the discriminatory power among groups was much better using craniometric variables (with less covariance among traits; solow, 1966) than an equivalent battery of tooth crown dimensions. materials and methods the data analyzed here consist of maximum mesiodistal (md) and buccolingual (bl) tooth crown dimensions of all 14 permanent tooth types, omitting m3s. measurements were made on the full-mouth dental casts of 100 american whites and 100 american blacks using electronic-readout sliding calipers with the beaks machined to fit well into the embrasures between teeth. measurement technique followed that described by selmer-olson (1949). there was an equal number of males and females in each race, and the subjects were contemporary american adolescents with all 28 teeth fully erupted without any restorations that would affect the measurements. teeth on just one side of the mouth were measured (either left or right, on an individual basis), but numerous studies have shown that the variance attributable to side is meager and due to just bilateral asymmetry plus technical error and may safely be ignored without biasing the other effects (e.g., lundström, 1948; potter and nance, 1976). statistical analysis it is implausible from what is known about odontometrics (e.g., kieser, 1990; hillson, 1996) to suppose that either genetic or environmental variation in tooth size is distributed across the dentition in even a vaguely uniform manner. instead, some of the axes of variation will account for appreciably more than other sources of variation. six axes of variation were estimated in the present study. variation was compared by (1) race, (2) sex, (3) arcade (maxilla or mandible), (4) tooth type (incisors, canines, premolars, and molars), (5) dimension (mesiodistal versus buccolingual crown diameters), and (6) position (the mesial or distal tooth within a morphogenetic field). to find out how the variance in tooth size is apportioned across these six axes, model ii, maximum-likelihood estimates of variance components were estimated (hartley et al., 1978) using the sas procedure varcomp (sas, 1989). two “races” were contrasted, american blacks and whites, but the perspective is to view these as random samples from the “universe” of possible races (e.g., coon, 1965). similarly, any number of crown dimensions could be measured on a tooth (cf. corruccini, 1977, 1978; black, 1979; fitzgerald and hillson, 2002), the conventional two assessed here (i.e., the standard md and bl dimensions) are best viewed as a sample of two picked from a population of dimensional possibilities. results and discussion multivariate analysis most of the total variance for odontometrics is shared (common) rather than unique variance. this has long been recognized (e.g., garn et al., 1965, 1968; moorrees and reed, 1964) insofar as all md and bl crown dimensions are positively intercorrelated with one another throughout the dentition. this is true for the present data set (table 1) where every one of the 378 pairwise comparisons is positively and significantly correlated at p < 0.001 (n = 200 for each comparison). this means that “size” is a pervasive controlling factor throughout the dentition. it also means that (1) tooth size can be predicted with some accuracy from other tooth sizes (e.g., moyers, 1988; tanaka and johnston, 1974) but that (2) since all dimensions are intercorrelated, they all tend to estimate the same thing (namely “overall size”) rather than carrying unique, nonredundant information. developmentally, these statistical intercorrelations appear to reflect the communalities of a few rather than many axes of ontogenetic control (weiss, 1990; salazar-ciudad and jernvall, 2002). statistical redundancy also has been illustrated in the several studies of human tooth size using factor analysis (e.g., potter et al., 1968; harris and bailit, 1988). for the present data, there are just three orthogonal axes of shared variation among the 28 crown dimensions, with “overall size” accounting for most (83%) of this (fig. 1). the other two axes of variation are (1) bl breadths of the anterior teeth contrasted with md lengths of the cheek teeth (premolars and molars), accounting for 10% of the shared variation, and (2) md lengths of the incisors contrasted with bl breadths of the posterior teeth (canines, premolars and molars) accounting for 7%. collectively, these three axes of shared variation (i.e., variation not unique to a single crown dimension) is 73% of the total variation. pca has been performed across a broad range of human samples, showing concordant results and, thus, the nature of the covariance matrices probably is essentially independent of the population under study. it is obvious that these three canonical axes of metric control of the dentition are far fewer than the 28 variables measured for the dentition, and this “reduction” is due to statistical (and developmental) redundancy among crown sizes. variance components results from the sas program varcomp disclosed that, taking total variance as 100%, the shared variance accounted for by the six variables in the model was 79.2% while the residual variance, unique to individual measurements accounted for the other 21.8% (fig. 2). this is about a four-to-one ratio of explained to residual variances, suggesting that the six factors listed above do, variance components in tooth size 86 87 i1 i2 c p 1 p 2 m 1 m 2 i1 i2 c p 1 p 2 m 1 m 2 u i1 m d .8 06 . 33 9 .0 99 .0 10 .0 12 .1 29 .0 73 .4 13 .1 84 .0 12 .1 10 .1 28 .0 65 .0 56 .0 71 .0 23 .1 38 .0 17 .2 07 .0 02 .0 33 .1 47 .1 28 .1 44 .1 03 .0 32 .0 32 .0 04 u i2 m d .7 37 . 69 0 -.0 26 .1 15 .0 02 .1 76 .0 20 .0 29 .0 72 .1 73 .0 71 .0 22 .0 26 .0 09 .0 94 .2 58 .0 02 .0 30 .0 29 .0 81 -.1 04 .1 12 .1 43 .0 98 .0 41 -.1 09 .0 62 .0 70 u c m d .6 62 . 58 2 .7 22 .1 43 .0 71 .0 27 .0 89 .0 71 .0 49 .3 81 .0 25 .0 97 .1 35 .0 93 .0 69 .1 05 .2 32 .0 61 .0 67 .0 95 -.0 25 .0 56 .0 38 .0 20 .0 75 -.0 45 .0 27 .0 86 u p1 m d .6 73 . 66 2 .7 03 .8 84 .4 07 .0 84 .0 54 .0 58 .1 41 .0 12 .4 75 .0 19 .0 71 .0 16 .0 34 .0 26 .0 17 .2 27 .0 41 .0 58 -.0 45 .0 91 .1 03 .0 18 .0 40 -.0 55 .1 23 .1 88 u p2 m d .5 64 . 52 9 .5 84 .8 16 .7 48 .0 61 .0 32 .0 27 .0 04 .0 43 .1 08 .2 91 .0 14 .0 32 .0 95 .0 55 .0 26 .0 81 .1 85 .0 22 .0 89 .0 21 .0 06 .0 43 .0 43 .0 56 .0 19 .1 21 u m 1 m d .6 37 . 49 1 .6 17 .6 97 .6 59 .7 88 .4 18 .1 21 .0 21 .0 20 .1 25 .1 97 .3 18 .0 20 .0 29 .2 31 .1 35 .0 75 .0 07 .1 89 -.1 11 .1 01 .0 21 .0 34 .0 19 -.0 29 .0 79 .0 69 u m 2 m d .5 78 . 49 3 .6 20 .7 23 .6 71 .7 71 .7 68 .1 36 .0 38 .0 77 .0 94 .0 84 .0 31 .2 64 .0 47 .0 92 .1 11 .0 30 .0 23 .1 87 .2 13 .1 73 .0 72 .0 58 .0 57 .0 39 .0 14 .0 18 l i1 m d .8 14 . 66 3 .6 10 .6 35 .5 17 .5 72 .5 02 .7 87 .4 08 .0 45 .1 24 .0 16 .0 77 .0 44 .0 83 .1 22 .0 95 .0 36 .0 12 .0 08 .0 18 .1 38 .0 36 .1 87 .0 46 .0 37 .1 32 .0 82 l i2 m d .7 77 . 68 3 .6 20 .7 03 .5 62 .5 91 .5 32 .8 23 .7 86 .1 92 .0 45 .0 43 .0 41 .1 03 .0 07 .0 13 .0 72 .0 23 .2 16 .0 51 -.0 29 .0 34 .0 59 .0 42 .0 45 .0 35 .0 67 .0 64 l c m d .7 05 . 66 3 .7 87 .7 39 .6 18 .6 35 .6 17 .6 44 .7 08 .7 83 .0 38 .0 42 .1 03 .0 41 .0 73 .0 18 .0 27 .0 07 .0 43 .0 08 .0 98 .0 83 .0 33 .2 21 .0 91 .1 00 .0 57 .0 14 l p1 m d .6 40 . 64 6 .6 67 .8 91 .7 45 .6 87 .7 15 .6 33 .6 94 .7 34 .8 66 .3 00 .0 64 .1 73 .0 67 .1 33 .1 15 .0 13 .0 61 .0 18 .0 39 .0 82 .0 06 .0 08 .1 05 -.0 14 .0 32 .1 44 l p2 m d .5 86 . 55 6 .6 59 .8 06 .7 84 .7 28 .6 83 .5 66 .6 27 .7 06 .8 34 .8 11 .0 87 .0 29 .0 73 .0 54 .0 38 .0 05 .0 57 .0 32 -.0 12 .0 11 .0 79 .0 46 .0 48 .1 65 .0 76 .0 54 l m 1 m d .6 18 . 54 8 .6 69 .6 95 .6 26 .7 94 .7 07 .5 53 .5 98 .6 87 .7 21 .7 30 .7 90 .3 51 .0 65 .0 06 .0 43 .1 20 .0 96 .0 38 -.0 98 .0 10 .0 45 .1 71 .0 46 -.0 86 .2 11 .0 00 l m 2 m d .6 19 . 56 4 .6 19 .7 44 .6 64 .7 30 .7 83 .5 99 .6 42 .6 81 .7 71 .7 22 .7 90 .8 08 .1 30 .0 50 .0 41 .0 96 .0 27 .0 79 .2 28 .0 81 .0 04 .0 05 .0 84 -.0 32 .1 12 .2 28 u i1 b l .4 22 . 44 9 .4 68 .4 06 .3 78 .3 61 .3 93 .4 20 .3 79 .4 20 .3 60 .3 28 .3 70 .3 54 .6 04 .3 25 .1 48 .0 63 .0 42 .1 69 .0 44 .0 93 .1 74 .0 35 .0 16 -.0 27 .0 77 .0 38 u i2 b l .4 99 . 57 7 .4 90 .5 29 .4 48 .5 03 .4 90 .4 33 .4 47 .5 17 .5 24 .4 53 .4 78 .4 97 .6 63 .6 54 .2 13 .1 32 .0 64 .0 21 .0 07 .1 70 .0 19 .0 92 .0 12 -.0 13 .0 68 .1 02 u c b l .4 51 . 43 4 .6 07 .5 27 .4 81 .4 20 .5 34 .4 15 .3 81 .5 61 .4 73 .4 66 .4 62 .5 08 .5 91 .6 04 .6 75 .0 38 .1 52 .0 59 .0 94 .1 02 .1 33 .2 63 .0 51 .1 25 .0 24 .0 72 u p1 b l .6 44 . 59 2 .6 87 .8 10 .7 10 .6 46 .6 94 .5 66 .5 92 .7 30 .7 78 .7 46 .6 86 .6 83 .4 94 .5 83 .6 23 .8 67 .4 94 .0 08 .1 55 .1 23 .0 93 .0 49 .1 92 .0 10 .0 46 .0 33 u p2 b l .6 39 . 56 5 .6 42 .7 52 .7 23 .6 21 .6 77 .5 38 .5 23 .7 00 .7 31 .7 29 .6 23 .6 54 .4 55 .5 38 .6 39 .8 84 .8 55 .0 99 -.0 16 .1 29 .1 24 .0 65 .1 22 .2 25 .0 40 .0 23 u m 1 b l .6 02 . 48 2 .6 38 .6 07 .5 52 .6 43 .5 81 .5 52 .5 59 .6 52 .5 99 .6 07 .6 57 .6 28 .5 30 .5 19 .5 68 .7 10 .6 86 .7 92 .4 12 .0 57 .0 11 .0 03 .0 19 -.0 21 .3 09 .1 39 u m 2 b l .5 97 . 49 7 .6 38 .6 89 .6 33 .6 31 .7 14 .5 49 .5 58 .6 80 .6 80 .6 49 .6 57 .7 46 .4 87 .5 21 .6 17 .7 64 .7 27 .8 02 .8 00 .0 26 .0 49 .0 00 .0 09 -.0 85 .0 40 .1 89 l i1 b l .4 75 . 46 6 .4 80 .4 34 .3 92 .3 78 .4 61 .4 94 .4 61 .4 73 .4 06 .3 95 .3 80 .4 69 .6 02 .5 89 .5 58 .4 80 .4 97 .5 30 .5 05 .7 05 .5 10 .1 94 .0 56 .0 14 .0 07 .0 46 l i2 b l .5 91 . 51 3 .5 83 .5 89 .5 00 .4 69 .5 03 .5 80 .5 76 .6 03 .5 43 .5 24 .4 73 .5 31 .6 29 .5 99 .6 36 .6 20 .5 84 .6 06 .5 85 .7 87 .7 70 .1 85 .1 04 -.0 65 .0 36 .0 35 l c b l .4 08 . 34 8 .4 70 .3 96 .3 29 .3 01 .3 61 .3 02 .3 18 .5 15 .3 54 .3 32 .2 78 .3 46 .4 79 .5 19 .6 32 .4 82 .5 08 .4 70 .4 66 .6 04 .6 50 .6 08 .1 33 -.0 82 .0 48 .0 03 l p1 b l .5 92 . 55 4 .6 16 .7 16 .6 33 .5 92 .6 30 .5 54 .5 81 .7 10 .7 23 .7 07 .6 22 .6 27 .4 50 .5 24 .5 78 .8 15 .7 95 .6 68 .6 90 .4 87 .6 18 .5 10 .7 64 .2 63 .0 05 .0 83 l p2 b l .5 38 . 44 9 .5 50 .6 30 .6 13 .5 41 .5 72 .4 96 .5 05 .6 31 .6 28 .6 80 .5 48 .5 63 .3 40 .4 03 .5 40 .7 21 .7 61 .5 99 .6 08 .3 98 .4 91 .3 91 .7 49 .6 89 .1 29 .1 23 l m 1 b l .5 59 . 46 7 .5 84 .5 78 .5 31 .6 25 .5 70 .4 77 .5 21 .6 09 .5 81 .6 26 .6 87 .6 09 .3 74 .4 12 .5 09 .6 69 .6 39 .7 75 .6 81 .4 42 .5 31 .4 08 .6 48 .6 33 .7 46 .3 80 l m 2 b l .5 95 . 51 6 .5 84 .6 47 .5 44 .5 80 .6 13 .5 56 .5 55 .6 36 .6 08 .6 01 .6 43 .6 98 .4 16 .4 42 .5 76 .7 08 .6 78 .7 61 .7 67 .5 08 .5 90 .4 48 .6 86 .6 48 .7 83 .7 75 t a b l e 1 . p ar ti al c or re la ti on c oe ffi ci en ts a bo ve t he m ai n d ia go n al , c ov ar ia n ce s on t he d ia go n al , a n d fu ll c or re la ti on c oe ffi ci en ts b el ow t he d ia go n al m ax il la m es io d is ta l b u cc ol in gu al m an d ib le m an d ib le m ax il la i1 i2 c p 1 p 2 m 1 m 2 i1 i2 c p 1 p 2 m 1 m 2 e.f. harris 86 87 fig. 1. results of principal components analysis on the 200 cases in the present study (28 crown dimensions). top: distribution of eigenvalues showing how most of the variation is in the first canonical component and how quickly the subsequent values descend, so that just the first three are larger than 1.0. the other three panels are graphs of the variables’ weights on each of the three principal components. collectively, account for most of the variability in this data set in the statistical sense. variance components of the six factors tested here are expressed as percentages of the explained variance (table 2). caveat partitioning total phenotypic variance into the relative fractions due to the six sources (listed above) is done to disclose differences in the relative contributions of these contributors to anatomic variation. so, for example, variations among the four tooth types (58.8% of total) is found to be enormously greater than variations between the md and bl crown diameters at 2.5% (i.e., between the two conventional axes used to reflect size pc i pc ii pc iii variance components in tooth size 88 89 table 2. estimates of the proportion of variance for each of the 7 parameters in the model source estimate percentage tooth type 2.47247 58.76 arcade 0.20484 4.87 race 0.14707 3.49 dimension 0.10735 2.55 sex 0.03633 0.86 position 0.01656 0.39 residual 0.83461 19.84 total 100.00 fig. 2. pie chart showing the apportionment of tooth size variation based on the six variables in the model (see text for details). variation). whether large or small, these components do not address whether there are statistically significant differences between groups within one of these six canonical dimensions. for example, the smallest source of variation in the present analysis is “position”—whether a tooth is the mesial, stable tooth or the distal, variable tooth within a morphogenetic field (i, p, m). even though position only accounts for 0.4% of the total variance, there still are highly significant statistical differences in mean size and in variance between mesial and distal teeth within a field (kieser, 1990). consequently, these two issues (source of variation versus statistical significance) are unrelated issues. tooth type by far, the largest variance component (82.8%) is tooth type, namely whether the tooth is an incisor, canine, premolar, or molar (fig. 3). this finding has an intuitive appeal because heterodonty—the segmentation of the dentition into functionally specialized tooth types (incisors for nipping, canines for piercing, premolars for trituration, and molars for crushing)—is the fundamental arrangement of the primate dentition (todd, 1918; butler 1939, 1956; swindler, 2002). the other anatomic effects in the present analysis simply involve duplication within the fields: duplication across the upper and lower arch producing structurally similar antagonists; duplication of a distal tooth creating the short meristic series that weiss (1990), jernvall (2000; jernvall and jung 2000), and others point out is an efficient method of increasing the number of structures, essentially by duplicating existing ones. the other sort of duplication (not included here) is tied to the ontogeny of bilateral symmetry, where left and right paired structures develop, apparently using the same genetic information, symmetrically across the midline. it would seem, then, that the four morphogenetic fields (one for each tooth type) constitute the basic organizing theme—with most of the variation among fields—and that, within fields, teeth enumerated front-to-back (the “pole” and the “variable” tooth; dahlberg, 1945, 1951), side-to-side (bilateral symmetry), and craniocaudally (creating analogous tooth morphologies in the two jaws) consume comparatively little variation. in a practical sense, this large variance due to tooth type implies that dental anthropologists commonly will want to include variables from all tooth types (i, c, p, m) rather than multiple measurements within a tooth type, since tooth type is the canonical axis of variation. arcade while it is a distant second in terms of absolute variance, arcade (fig. 4) counts for the next-largest component of variance (6.9%), which is in concert with the results of factor analysis of dental metrics showing that, aside from an overall size effect, most factors or principal components (i.e., intercorrelated multivariable dimensions of teeth) typically are arcade-specific (e.g., potter et al., 1968; brown and townsend, 1979). perhaps this has been shown most clearly by potter et al. (1976) who characterized the few axes of genetic variation in the dentition. one genetic factor was bilateral symfig. 3. graph of mean tooth size by tooth type. e.f. harris 88 89variance components in tooth size metry; every genetic factor identified for a dimension on one side included the antimeric dimension on the other. secondly, potter disclosed a buccolingual crown size factor that extended throughout the maxillary (but not the mandibular) teeth. thirdly, a genetic factor influenced both md and bl dimensions of the mandibular anterior teeth. it is noteworthy that these genetic factors control regions of the dentition, not specific teeth. recent computer modeling (salazar-ciudad and jernvall, 2002) shows comparable results, namely that controlling just a few parameters can account for both the ontogenetic and phylogenetic variations within and among tooth types, both metrically and morphologically. in the present study, figure 4 displays the arcade differences graphed across the 14 tooth crown dimensions. race the estimate of variance for “race” in this study might be criticized because only two groups were included and because american blacks and whites have experienced several generations of low level gene flow, primarily from whites to blacks (literature reviewed in pollitzer, 1999). on the other hand, subsaharan africans and american whites are at either end of the contemporary spectrum of human tooth sizes (harris and rathbun, 1991), except of course for the megadont native australians (e.g., smith et al., 1981). odontometric studies of american blacks and whites routinely find that blacks possess significantly larger teeth (richardson and malhotra, 1975; macko et al., 1979; vaughan and harris, 1992). in the future, it may be informative to increase the mix of ethnic samples in this assessment of the sources of tooth size variation. the critical issue, however, is recognition of the small component of variance attributable to the black-white difference, estimated here at 3.5% (fig. 5). the minor contribution of “race” is no longer surprising (lewontin, 1972), but these data are confirmatory, using quite a different tissue system, that races have been defined historically using very superficial criteria, whereas the great preponderance of variation is among individuals within groups, not among them. dimension dimension of the tooth crown—whether the crown is measured mesiodistally or buccolingually—accounted for 3.6% of the total variance. this is interesting because it shows that these geometrically orthogonal axes of a fig. 4. top: graphs of the mean crown sizes by tooth and arcade and plot of the maxillary-minus-mandibular size differences (bottom). 90 91 crown are largely coupled in terms of their ontogeny and genetic control. if these two commonly-measured axes of crown size (md and bl) were not strongly related, one would expect appreciably more variance to be due to this contrast of measured dimensions. researchers who have studied the genetic control of tooth size (e.g., sofaer et al., 1971; potter et al., 1976; townsend and brown, 1978) have commented on differences between md and bl dimensions, but the results often are inconsistent among studies, suggesting that sampling fluctuations may be at work. the suggestion has been advanced that md dimensions have lower heritabilities than bl dimensions because teeth compete for size of the dental lamina in the dental arch. in contrast, bl dimensions do not. this scenario seems to be insufficient as concerns a couple of developmental points. teeth do not develop from the dental lamina—like beads on a string—instead, they develop from projections of condensed mesenchyme (i.e., the presumptive dental papilla) that extend away from the presumptive occlusal plane, with considerable space between them (arey, 1965; slavkin, 1974; ooë, 1981). the tooth buds develop in a three-dimensional array such that, while their bony crypts may overlap mesiodistally, they are offset mediolaterally and craniocaudally (van der linden and duterloo, 1976; duterloo, 1991). teeth do not compete for space until their fully formed crowns erupt into the oral cavity where underdeveloped arch size may cause an arch-size to tooth– size discrepancy (little, 1975). the high prevalence of crowding in contemporary westernized populations is a recent epidemiological problem that seems to be predominately acquired rather than inherited (corruccini and potter, 1980; harris and smith, 1980). sex it is well documented that males have bigger teeth than females as statistical averages (e.g., mijsberg, 1931; gonda, 1959; garn, 1966; garn et al. 1964, 1967; harris and bailit, 1987), though the amount of sex difference is specific to a population, not a fixed effect (hanihara, 1978). it is a bit surprising, then, that variance due to sex accounted for just 1.2% of the total variation in the present study (fig. 6). on the other hand, humans are characterized by their trivial sexual dimorphism in tooth size compared to the great apes (e.g., harvey et al., 1978; swindler, 2002). garn et al. (1967) showed that the canine was the most dimorphic tooth in humans, at 4-6% depending on the group studied, which pales against such nonhuman primates as papio and pan, where the canine is more than half again as large in males as in females. the issue should also be considered that univariate analysis tends to exaggerate sex differences because redundant male-female differences are included in each test (potter, 1972). ditch and rose (1972) used discriminant functions analysis to correctly determine sex in an average of fig. 5. plot of crown dimensions by race (top) and black-minus-white differences in mean size showing that black have larger means throughout the dentition (bottom). e.f. harris 90 91variance components in tooth size 93% of their cases (depending on the set of variables analyzed), and garn and coworkers (1977, 1978) arrived at similar success rates. brown and townsend (1979) reported lower correct allocations (ca. 75% or less) using data from aboriginal australians—the same as reported by hanihara (1979)—indicating that the degree of sexual dimorphism is not tied to the tooth sizes of a group per se. in passing, researchers also have provided discriminant functions based on crown sizes of the primary teeth that correctly identify sex better than expected from chance (devito and saunders, 1990; tsutsumi et al., 1993) even though the primary teeth are much less dimorphic (harris, 2001). position depending on their position within a morphogenetic field (i, p, m), teeth are labeled as “stable” or “variable” (butler, 1939; dahlberg, 1945). this dichotomy refers to the metric and morphological variation exhibited by a tooth. a stable, early-forming tooth is larger, possesses more and larger cusps and other crown features, and is less likely to be reduced in size or congenitally absent. these and other considerations led dahlberg (1945, 1951, 1986) and others to characterize the “fields” of the human dentition (fig. 7). several studies have shown that the increased variability of distal “variable” teeth is due to diminished genetic control (e.g., lundström, 1948; alvesalo and tigerstedt, 1974). (as an aside, this study did not account for the apparent field reversal, where li1 is more variable than li2, which kjaer (1980) attributes to the weak vascular supply in the mandibular midline because of the symphysis menti.) the present study shows that position is a comparatively small axis of variation, estimated at 0.4%, making it the most trivial of the factors studied in this model. this also emphasizes the caveat (above) that estimating the relative sources of variation in the dentition is a different issue than whether particular teeth exhibit statistically significant differences. a key metrical attribute of a pole tooth within a field is its relative metric stability (townsend and brown, 1981). coefficients of variation are graphed in figure 8, where it is seen that it is not a foregone conclusion that the later-forming tooth possesses significantly great variance statistically. for the six contrasts in figure 8, just three achieved significance (α = 0.05 for one-tail tests). just the maxillary incisors (i2 > i1) and the upper and lower molars (m2 > m1) exhibit significantly more variance in one tooth vis-à-vis the other. in all these instances, the distal tooth is always the more variable tooth. fig. 6. plot of tooth crown dimensions by sex (top) and plot of the male-minus-female differences (bottom) showing that, characteristically, males have larger mean crown dimensions. 92 93 overview what are the major axes of variation in the permanent dentition in terms of tooth size? results of the present study show that the canonical axis is among tooth types, which accounts for more than half of the variation (59%). there is a dramatic drop-off after tooth type is accounted for. arcade (4.9%), race (3.5%), and crown dimension (2.6%) have only minor but comparatively intermediate values. least influential are sex (0.9%) and tooth position within a field (0.4%). none of these axes of variation hinges on any one tooth, and the fundamental lack of more and 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karger. little rm. 1975. the irregularity index: a quantitative score of mandibular anterior alignment. am j orthod 68:554563. macko dj, ferguson fs, sonnenberg em. 1979. mesiodistal crown dimensions of permanent teeth of black americans. j dent child 46:42-46. martin r. 1928. lehrbuch der anthropologie in systematischer dartellung. jena: gustav fischer. mijsberg wa. 1931. on sexual differences in the teeth of japanese. koninklijke akademie voor wetenschap 34: 1111-1115. moorrees cfa, reed rb. 1964. correlations among crown diameters of human teeth. arch oral biol 9:685-697. moyers re. 1988. handbook of orthodontics, 4th ed. chicago: year book medical publishers, inc. ooë t. 1981. human tooth and dental arch development. tokyo: ishiyaku publishers, inc. pollitzer ws. 1999. the gullah people and their african heritage. athens: university of georgia press. potter rhy. 1971. univariate versus multivariate differences 94 95 in tooth size according to sex. j dent res 51:716-722. potter rhy, nance we. 1976. a twin study of dental dimension. i. discordance, asymmetry and mirror imagery. am j phys anthropol 44:391-396. potter rhy, nance we, yu p, davis wb. 1976. a twin study of dental dimensions. ii. independent genetic determinants. am j phys anthropol 44:397-412. potter rh, yu pl, dahlberg aa, merritt ad, conneally pm. 1968. genetic structure of tooth size factors in size factors in pima indian families. am j hum genet 20: 89-100. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am jorthod 68:157-164. salazar-ciudad i, jernvall j. 2002. a gene network model accounting for development and evolution of mammalian teeth. proc natl acad sci 99:8116-8120. selmer-olson r. 1949. an odontometrical study of the norwegian lapps. skrifter utgitt av det norske videnskaps-akademi oslo, i. mat-naturv-klasse, no. 3. slavkin hc. 1974. embryonic tooth formation: a tool for developmental biology. oral sci rev p 6-136. smith p, brown t, wood wb. 1981. tooth size and morphology in a recent australian aboriginal population from broadbeach, south east queensland. am j phys anthropol 55:423-432. sofaer ja, bailit hl, maclean cj. 1971. a developmental basis for differential tooth reduction during hominid evolution. evolution 25:509-517. solow b. 1966. the pattern of craniofacial associations. acta odont scand 24:suppl 46. swindler dr. 2002. primate dentition: an introduction to the teeth of non-human primates. cambridge: cambridge university press. tanaka mm, johnston le. 1974. the prediction of the size of unerupted canines and premolars in a contemporary orthodontic population. j am dent assoc 88:798-801. todd tw. 1918. an introduction to the mammalian dentition. st louis: cv mosby company. townsend gc. 1976. tooth size variability in australian aboriginals: a descriptive and genetic study. ph.d. dissertation, university of adelaide, south australia. townsend gc, brown t. morphogenetic fields within the dentition. aust orthod j 1981;7:3-12. tsutsumi h, matsui n, morita y, sano e, okamura k, komura t, takei t. 1993. [sex determination with a discriminant function analysis of deciduous teeth size in plaster models.] nippon hoigaku zasshi 47:466-480. van der linden fpgm, duterloo hs. 1976. development of the human dentition—an atlas. hagerstown: harper and row. vaughan me, harris ef. 1992. deciduous tooth size standards for american blacks. j tenn dent assoc 72: 30-33. weiss km. 1990. duplication with variation: metameric logic in evolution from genes to morphology. yrbk phys anthropol 33:1-24. yamaguchi tp. 1997. new insights into segmentation and patterning during vertebrate somitogenesis. curr opin genet dev 7:513-518. the annual meeting of the canadian association for physical anthropology will be held in edmonton, alberta, october 23-25 of 2003. contributed papers and posters for a symposium on dental anthropology are welcome. for further information, contact dr. nancy lovell, department of anthropology, university of alberta, edmonton, t6g 2h4 canada. e-mail: nancy.lovell@ualberta.ca capa meeting e.f. harris decoding your subscription want to know when your subscription to dental anthropology expires? membership in the association and, thus, your subscription to dental anthropology is on an annual basis coinciding with the calendar year. have a look at the mailing label on the evelope that this issue arrived in, and you will see the year for which your dues have been paid. the year is located in parentheses to the right of your name. so, if the mailing label says “(2003)” you are paid to the end of this calendar year. in order to extend your membership, fill-out the relevant portions of the enclosed form—remember to include appropriate payment—and mail it to the secretary-treasurer of the association: dr. heather h. edgar maxwell museum of anthropology msc01 1050 1 university of new mexico albuquerque, new mexico 87131-0001 usa telephone: (505) 277-4415 e-mail: hjhedgar@unm.edu tihacek-sojic et al. 1997.3 pg5.jpg pg6.jpg pg7.jpg pg8.jpg pg9.jpg pg10.jpg pg11.jpg edgar 2004.3 54 55 the mean measure of divergence (mmd) has become the standard statistical technique for assessing biological affinities when using frequencies of dental morphological characteristics (scott and turner, 1997). there are several advantages in using this statistic: it is appropriate for nominal data, it is relatively easy to compute, and it is comparable among researchers. there is however, a drawback to using the mmd; it is only appropriately used when the traits being studied are independent. the assumption of independence is weak for several dental characteristics, so intertrait correlations must be tested, and traits that are correlated must be removed from of a mmd analysis. an alternative to mmd is the mahalanobis’ d2 statistic, which allows correlated features to be used in affinity measures (mahalanobis, 1936). however, as originally formulated, this statistic is useful only for metric, not nominal, data. konigsberg (1990) used a pseudo-mahalanobis’ d2 to determine biological affinity using non-metric data. this statistic has the potential to allow distance measures to be based on a greater variety and number of dental characteristics than the mmd. of course, like mmd, the d2 statistic has its drawbacks. the primary problems with the application of this statistic are its limited applicability when analyzing a number of traits with little or no correlation, the need for multiple observations per individual, and its relatively more difficult computation. because every trait must be compared to every other for each sample being studied, comparing more than a few traits at a time can become quite abstract one of the main uses of dental morphological data is to study patterns of affinities among populations. many different approaches to this purpose are available, each one having its own strengths and weaknesses. for this study, observations were made of the morphology of 614 african american and 327 european american dentitions (n = 941). each of these samples was divided into three groups based on the time in which they lived. affinities among the resulting six groups were estimated based on the dentitions, distance, and difficulty: a comparison of two statistical techniques for dental morphological data heather joy hecht edgar* laboratory of human osteology, maxwell museum of anthropology, university of new mexico, albuquerque, new mexioc 87131 address for correspondence: heather j. h. edgar, laboratory of human osteology, maxwell museum of anthropology, university of new mexico, albuquerque, nm 87131. email: hjhedgar@unm.edu frequencies of dental morphological characteristics, by the use of both the mean measure of divergence and a pseudo-mahalanobis’ d2. the results of these analyses are compared using a procrustes transformation that rotates and scales coordinates derived from distances until achieving the best fit. the two statistics produce similar, although not identical results. the appropriate use and relative value of each approach is discussed. dental anthropology 2004;17(2):55-62. arduous, even with a computer. additionally, the inclusion of a new sample for analysis requires the recalculation of all measures of affinity among groups, not simply the measures of affinity of the new sample with the original groups, as with the mmd. this study presents the results of a comparison of mmd and pseudo-d2 methods for determining biological affinity among several samples. the goals are to investigate whether the two types of analysis result in similar findings, and if not, to consider why. material the data for this study comes from the dentitions of 941 african americans and european americans, analyzed as part of a larger study of the microevolution of african american dental morphology. samples come from collections temporarily or permanently housed at the national museum of natural history, national museum of health and medicine, cleveland museum of natural history, university of tennessee health sciences center, ohio state university, and arizona state university. the samples were divided into six groups, based on ancestry and time period. the samples sizes and time periods are listed in table 56 57 1. for this study, a maximum of 136 observations of 32 morphological characteristics was possible per dentition. observation procedures were based on the arizona state university dental anthropology system (turner et al., 1991). no significant directional asymmetry of expression or sexual dimorphism was found, so rights and lefts were combined (with the greatest trait expression being represented), as were observations from males and females. observations were then dichotomized with guidance from haeussler et al. (1989), irish (1993), irish and turner (1990), scott and turner (1997), and turner (1987). all statistics were performed using the sas statistical package (sas institute inc., 1990). associations between traits were determined using the likelihood ratio statistic. the list of traits that was used for each analysis can be found in table 2. traits used in the mmd analysis are independent from each other. to invert the matrix of correlations, the d2 analysis requires that most variables have some tetrachoric correlation with all other variables. several variables were eliminated from d2 analyses because they were found to have little or no correlation with other variables, and thus the tetrachoric correlation matrix was singular. different variable combinations were used in each analysis because of the requirements of each statistics; traits should be uncorrelated for the mmd and correlated for the d2. statistical methods mean measure of divergence the mmd statistic was developed by c. a. b. smith, and was first used to look at changes due to inbreeding in mice (grewal, 1962; berry et al., 1967). berry and berry (1967) first applied it to the study of biological affinities or distance in humans. the mmd estimates biological distance between samples based on the degree of phenetic similarity (irish, 1997). the statistic requires an assumption of independence of traits. like d2, it is useful if trait expression varies in a population, when frequencies are 5-95% (de souza and houghton, 1977). some major benefits of its use are its ability to work with incomplete data and its applicability to samples as small as 10-20 observations. mmd is defined as: mmd=(∑(θ 1 θ 2 )2 (1/n 1 + 1/n 2 ))/c where θ 1 and θ 2 are the arc sin (sin-1) transformations of the observed frequencies in the two samples being compared, n 1 and n 2 are the sample sizes, and c is the number of characters employed (freeman and tukey, 1950). pseudo-mahalanobis’ d2 the pseudo-mahalanobis’ d2 is defined as the sum of squares of differences between corresponding mean values of two sets of measurements, weighted by the variance/covariance matrix (burnaby, 1966): d =2 χ χ χ χ ik jk ik jk −( ) −( )∑' where χ ik is the mean of expression for sample i for k traits, and χ jk is the same for sample j. the middle term (∑) is the pooled covariance matrix between the k traits (manly, 1994). in this study, the means of trait expressions are the threshold values corresponding to the trait frequencies in the samples (falconer, 1981), and the middle term is a pooled matrix of tetrachoric correlations between the traits (brown, 1977). these transformations account for correlations between characteristics being used (konigsburg, 1990; mizoguchi, 1977) and the threshold nature of dental morphological traits (scott and turner, 1997). early middle late born born born circa circa circa 1650-1850 1825-1910 1920-1960 total african american 35 414 165 614 european american 33 139 155 327 total 68 553 320 941 table 1. sample compositions max mmd mand mmd max d2 mand d2 dias li2ss ui2ss li1ss ucss lcdr ucss li2ss ui1lc lp3lc ui1lc lp4lc ui2ds lp4lc ui2td lm2mt ui2ig lm1af uctd lm1ps um3ca lm2gp ucdr lm2ps uctd lm1dw up3md lm2c5 ucdr lm1mt up4md lm1c6 up3md lm2ps um1mc up4md lm2c5 um2mc um2mc lm1c6 um1hc um1hc lm2c7 um1c5 um2c5 um2c5 um2cb um1cb um2cb table 2. dental characters used in each analysis h.j.h. edgar 56 57statistics for dental morphology procrustes’ transformation the purpose of this statistic is to rotate and scale two sets of coordinates so as to achieve the best fit between them (gower, 1971, 1975). for this study, the coordinates come from principal coordinates analysis of four distance matrices, and represent the first two axes of each matrix. the better the fit between two sets of coordinates, the smaller the summed deviations should be. gower (1971) refers to the statistic as r2 (for residual), but it can also be found as s2 (for sum of squares) (goodall, 1991) and m2 (for minimum)(jackson, 1995). r2 is defined as: r2= ∑ ∆2(p i p i *), where p i and p i * represent the corresponding points in two different sets of coordinates. the r2 statistic is the sum of squared differences after rotation and scaling. the smaller the r2, the smaller the difference is between the two sets of coordinates. for this study, a small r2 will indicate good agreement between the mmd and d2 statistics. results before discussing the direct comparison of statistical methods, an examination of the pictures presented by each analysis is in order. due to the difficulty in performing pseudo-mahalanobis’ d2 with a large quantity of traits, maxillary and mandibular traits were considered separately. measures of affinity results for mmd analyses based on maxillary and mandibular traits can be seen in tables 3 and 4, respectively. the maxillary traits show a separation between african americans (aa) and european americans (ea) at all time periods. there is a closer relationship between early and middle ea than either to late ea. early aa is different from all groups, with middle and late aa being most like late ea. analysis of the mandibular traits emphasizes the split between ea and aa and minimizes other details. results for the d2 analyses are summarized in tables 5 (maxillary traits) and 6 (mandibular traits). the results for the maxillary traits seem to emphasize the time difference between groups rather than differences in ancestry. late and middle aa and ea cluster most closely, with early aa and ea being very distant from each other and all other groups. the results based on the mandibular trait d2 are the most difficult to characterize. there is a large difference between early and middle aa, and a relatively small difference between middle and late aa. while the indication that change in the african american gene pool slowed down after the civil war reflects known historical patterns of admixture (davis, 1991), it does not explain the apparent similarity of early ea and middle aa, the smallest distance in the matrix. this information is graphically presented in figure 1, which shows the principal coordinates of the relationships among the six groups resulting from mmd analyses, late aa late ea middle aa middle ea early aa early ea late aa 0 0.113 0.074 0.443 0.244 0.402 late ea 0.113 0 0.113 0.231 0.395 0.239 middle aa 0.074 0.113 0 0.222 0.187 0.247 middle ea 0.443 0.231 0.222 0 0.292 0 early aa 0.244 0.395 0.187 0.292 0 0.218 early ea 0.402 0.239 0.247 0.000 0.218 0 table 3. mmd distances, maxillary traits late aa late ea middle aa middle ea early aa early ea late aa 0 0.507 0.094 0.471 0.122 0.488 late ea 0.507 0 0.525 0.119 0.601 0.148 middle aa 0.094 0.525 0 0.401 0.122 0.374 middle ea 0.471 0.119 0.401 0 0.449 0.000 early aa 0.122 0.601 0.122 0.449 0 0.410 early ea 0.488 0.148 0.374 0 0.410 0 table 4. mmd distances, mandibular traits 58 59 late aa late ea middle aa middle ea early aa early ea late aa 0 4.175 7.692 7.755 6.676 17.243 late ea 4.175 0 4.472 4.563 10.015 10.769 middle aa 7.692 4.472 0 3.184 7.982 8.698 middle ea 7.755 4.563 3.184 0 8.303 6.499 early aa 6.676 10.015 7.982 8.303 0 10.295 early ea 17.243 10.763 8.698 6.499 10.295 0 table 5. d2 distances, maxillary traits late aa late ea middle aa middle ea early aa early ea late aa 0 1.473 8.630 3.593 8.725 8.302 late ea 1.473 0 4.598 4.714 6.300 5.243 middle aa 8.630 4.598 0 8.442 7.281 2.442 middle ea 3.593 4.714 8.442 0 5.040 7.459 early aa 8.725 6.300 7.281 5.040 0 8.800 early ea 8.302 5.243 2.448 7.459 8.800 0 table 6. d2 distances, mandibular traits �� ����������������������������� ���� ���� ���� � ��� ��� ��� ��� ���� ���� ���� ���� � ��� ��� ��� ��� ������ � � �� �� ������������� �������������� ������� ������� ������ ������ �������� �������� ������� ������� ������ ������ �������� �������� fig. 1. principal coordinates for mmd analyses. h.j.h. edgar 58 59statistics for dental morphology �� ���� �� ���� � ��� � ��� � ��� ���� �� ���� �� ���� � ��� � ��� � ��� ������ � � �� �� ������� ������������� ������������ � ������� ������������ �������� �������� ������� ������� ������ ������ �������� �������� fig. 2. principal coordinates for d2 analyses. �� ���� ���� ���� ���� � ��� ��� ��� ��� ���� ���� ���� ���� � ��� ��� ��� ��� ������ � � �� �� ������� ������� ������ �������� �������� ������ ������������� �������������� ������� ������� ������ ������ �������� �������� fig. 3. mmd principal coordinates after procrustes transformation. 60 61 fig. 5. principal coordinates of residuals. fig. 4. d2 principal coordinates after procrustes transformation. �� ���� ���� � ��� ��� ��� ��� ���� ���� ���� ���� ���� � ��� ��� ��� ��� ������ � � �� �� ������� ������� ������ �������� �������� ������ ������������� �������������� ������� ������� ������ ������ �������� �������� �� ���� ���� ���� ���� � ��� ��� ��� ��� �� ���� �� ���� � ��� � ��� � ������ � � �� �� ������� �������� ������� ������ h.j.h. edgar 60 61statistics for dental morphology and figure 2, which shows the same relationships for d2 analyses. procrustes analysis figures 3 and 4 show the relationships between the six samples after rotation and scaling of the principal coordinates for mmd and d2, respectively. the coordinates for maxillary mmd results acting as a baseline for both tables. each of the other groups has been redrawn to its best fit, meaning the one that yields the smallest residual. the residuals between all the groups are summarized in table 7. there is no test of significance for r2, but it can be seen that all the values are relatively small except for between the d2 for maxillary and mandibular characteristics. it is possible to simplify this table by performing a principal coordinates analysis for this r2 matrix and display the relationships in the simplest geometric space. a graph of these coordinates shows relationship between the four methods of determining affinity. figure 5 shows that the two mmd matrices are in nearly perfect agreement. the two d2 matrices are quite different from each other, but neither is more different from the mmd matrices than the other. it remains to be explained why the d2 matrices are so different from each other. one possible explanation is a lack of differences between the samples being studied in these particular traits. in fact, among the traits used for the mandibular d2 analysis, there is half the average difference in expression between groups as there is in the maxillary d2 and mmd, and one quarter as much difference as in mandibular mmd. conclusions overall, there is very good agreement between the biological distance matrices generated using mmd and pseudo-mahalanobis’ d2 statistics. both statistics have their place in the analysis of biological distance, especially when utilizing characteristics of dental morphology. as with all statistics, the mmd and d2 are limited by the data they analyze. if there is little difference between samples for the characteristics in question, the results will show small distances; if the differences are large for those particular characteristics, the distances will be large as well. a careful evaluation of the data should be made before attempting any measure of affinity. when there are many traits available for analysis and they have little inter-trait correlation, mmd is appropriate. when the data consist of a relatively few, correlated traits, a pseudo-mahalanobis’ d2 is more accurately applied, as it makes no assumption about a lack of correlation between traits. in a large study, the use of both statistics may allow analysis of more of the collected data. if all things are equal and either statistic is applicable, mmd is simpler to use and more widely comparable. acknowledgements this research was supported by a grant from the graduate student alumni research award of ohio state university and by national science foundation grant #0087400. thanks go to dr. paul sciulli and all the people and institutions that allowed access to their collections for this project. literature cited berry ac, berry rj. 1967. epigenetic variation in the human cranium. j anat 101:361-379. berry ac, berry rj, ucko pj. 1967. genetical change in ancient egypt. man n.s. 2:551-568. brown mb. 1977. the tetrachoric correlation and its asymptotic standard error. appl statist 26:343-351. burnaby tp. 1966. growth invariant discriminant functions and generalized distances. biometrics 22:96210. davis fj. 1991. who is black? one nation’s definition. university park, pa: pennsylvania state university press. de souza p, houghton p. 1977. the mean measure of divergence and the use of non-metric data in the estimation of biological distances. j arch sci 4:163-169. falconer ds. 1981. introduction to quantitative genetics. new york : longman. freeman mf, tukey jw. 1950. transformations related to the angular and square root. ann math stat 21: 607-611. goodall cr. 1991. procrustes methods and the statistical analysis of shape (with discussion). j roy stat soc b 53:285-340. gower jc. 1971. statistical methods of comparing different multivariate analyses of the same data. in: hodson fr, kendall dg, tautu p, editors. mathematics in the archaeological and historical sciences. edinburgh: edinburgh university press. gower jc. 1975. generalized procrustes analysis. psychometrika 40:33-51. grewal ms. 1962. the rate of genetic divergence in the c57bl strain of mice. genet res 3:226-237. haeussler am, irish jd, morris dh, turner cg ii. 1989. morphological and metrical comparison of san and central sotho dentition from southern africa. am j phys anthropol 78:115-122. irish jd. 1997. characteristic highand low-frequency dental traits in sub-saharan african populations. am j phys anthropol 102:455-467. irish jd. 1993. biological affinities of late pleistocene through modern african aboriginal populations: the dental evidence. ph.d. dissertation, arizona state university. irish jd, turner cg. 1990. west african dental affinity of late pleistocene nubians: peopling of the eurafrican62 63 south asian triangle ii. homo 41:42-53. jackson da. 1995. protest: a procrustean randomization test of community environment concordance. ecoscience 2:297-303. konigsberg lw. 1990. analysis of prehistoric biological variation under a model of isolation by geographic and temporal distance. hum biol 62:49-70. mahalanobis pc. 1936. on the generalized distance in statistics. proc nat inst sci india 12:49-55. manly bfj. 1994. multivariate statistical methods: a primer. london: chapman and hall. mizoguchi y. 1977. genetic variability in tooth crown characters: analysis by the tetrachoric correlation method. bull nat sci mus, series d 3:37-62. sas institute inc. 1990. sas/stat users guide, version 6, 4th ed. cary, nc: sas institute, inc. scott gr, turner cg ii. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. turner cg, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: m kelley, larsen cs, editors. advances in dental anthropology. new york: wileyliss, p 13-31. turner cg. 1987. late pleistocene and holocene population history of east asia based on dental variation. am j phys anthropol 73:305-321. h.j.h. edgar 13th international symposium on dental morphology first announcement the 13th international symposium on dental morphology is taking place from wednesday 24 to saturday 27 august 2005, hosted by the university of lódz, poland. the conference web-site is at: http:// www.biol.uni.lodz.pl/antropolog/conference/index.html files can be downloaded from the web-site for 1) symposium registration, 2) presenter’s information, and 3) guideline for manuscript preparation with presenter’s instructions. documents should be completed and return by the 28th february 2005. scientific program: the scientific programme will be held in the conference facilities at the university of lódz and will follow the general pattern of previous meetings, with single oral and poster sessions. abstracts: we welcome abstract submission, with the deadline of 28th february 2005. an abstract submission form and a presenter’s form is available from the organizers, with the choice of preferred option of poster or oral communication. symposium proceedings: the symposium proceedings will consist of the presentations as short papers. our proposed deadline for manuscripts will be 31th may 2005. see information on the web-site for submission formats. the symposium and the accommodation are organized in the university conference centrum. the centrum is set in the university district in very pleasant grounds, close to the city center (piotrkowska street). we will be using all the conference facilities on site. the accommodation includes single and double rooms. travel from this venue to our social events and return is included in the fee. symposium costs: participant 130 euro by 28.02.2005 180 euro by 31.05.2005 accompanying person 50 euro by 28.02.2005 80 euro by 31.05.2005 please note: we regret that any cancellation after 01.07.2005 will not be refundable. conference fee covers: book of abstracts, the symposium proceedings, attendance to all sessions, refreshments during the meeting, conference facilities, the welcome reception, sightseeing of lódz, grill party and the gala dinner. much more information is available on the website. editor’s note: this information is abstracted from a detailed e-mail sent in early october. be certain to refer to the web-site for specifics. http://www.biol.uni.lodz.pl/antropolog/conference/index.html http://www.biol.uni.lodz.pl/antropolog/conference/index.html cucina et al. 2008.2 46 the dental morphology of maya populations belongs to the sinodont family (turner, 1990) and falls into the sino-american group (scott and turner, 1997). it is characterized by, among other features, a high frequency of undivided roots in the lower second molar (scott and turner, 1997). root morphology is one of the many traits commonly employed in dental studies of population affinities. mandibular second molars are described according to a oneor two-roots dichotomy (with the very rare cases of three roots falling into the two-roots category) (turner et al., 1991; scott and turner, 1997). the frequency of single rooted second lower molars in north and south american native populations has been reported to range between 30% and 35% (scott and turner 1997). frequency of such traits in the maya region ranges between 15% and 30% (jacobi, 2000; wrobel, 2004; cucina et al., 2005). from an endodontic perspective, single rooted lower second molars are described as c-shape, due to the pulp chamber morphology that appears as a “c” in the roots´ cross section (see jafarzaed and wu, 2007 for a review). generally, the fused root is associated with the c-shape canal, even though the endodontic treatment that exposes the chamber cannot detect the actual morphology of the root. the c-shape chamber morphology has been reported to be strongly associated with certain ethnic affiliations. high frequencies of c-shape second molars have been registered in sinodont populations such as chinese, japanese and koreans, while being relatively uncommon in caucasoid or african peoples (yang et al., 1988; habbad et al., 1999; gulabivala et al., 2001; seo and park, 2004; jin et al., 2006; jafarzaed and wu, 2007). the morphology of root and c-shape canal in prehispanic and modern maya groups from northern yucatan andrea cucina,1 elma vega lizama,2 marco ramírez,2 g. alvarado cárdenas,2 and vera tiesler1 1facultad de ciencias antropológicas, universidad autónoma de yucatán, mérida, yucatán, méxico; 2facultad de odontología, universidad autónoma de yucatán, mérida, yucatán, méxico abstract one-rooted mandibular second molars are labelled “c-molar” because of the root’s morphology. the frequency of c-molars is strongly associated with ethnic origin, being most common in north-east asians. the present study analyzed the frequency of one-rooted molars and associated pulpal chamber in 48 prehispanic mayans and in 142 modern subjects studied at the school of endodontics, uady. the frequency of one-rooted molars in the prehispanic sample is 35%, with 32% of these having c-canals. similarly, 42 of 142 correspondence to: andrea cucina, facultad de ciencias antropológicas, universidad autónoma de yucatán, mérida, km. 1 carretera mérida-tizimín, 97305 mérida, yucatán, méxico e-mail: acucina@yahoo.com maya population’s ancestry is sinodont, yet the conquest has led to admixture with european and african populations in the region, likely altering the genetic (and morphological) structure of the population. the goal of the present study is twofold: firstly, it aims at inferring the frequency of c-shape second molars in the maya populations according to their ancestry in order to assess the continuity or discontinuity in the prevalence of this trait in the region in an evolutionary perspective; secondly, the actual correlation between root and canal form is measured in order to infer to what extent the single root (as a morphological trait) corresponds to a c-shape canal in its inner structure. materials and methods the archeological sample consists of 48 mandibular second molars dated to the classic period (250-800 ad), recovered from xcambó and noh bec in northern yucatán. they were selected randomly (fig. 1); in most of the cases, the bony structure was missing or partly destroyed, so that the tooth had fallen out naturally. no tooth was extracted from its socket, since single rooted molars can be removed more easily than two-rooted ones, introducing a bias in its frequency. the one-rooted molars were then x-rayed to assess the shape of the (30%) modern teeth exhibit a c-canal. the similarity between ancient and modern samples suggests that genetic admixture since the european conquest has not affected trait expression, and it implies that the maya express the sinodontic pattern of dental morphology. endodontically, the significant correlation between c-molar and c-canal is an advantage for recognizing the canal’s anatomy if treatment is indicated. dental anthropology 2008;21(2):46-49. 47 canal (fig. 2). no archeological tooth was sectioned or partially destroyed to inspect the morphology of the inner chamber on ethical and legal grounds, as destructive analysis of archeological materials requires the permission of the archeology council under mexican law. once scrutinized, the teeth were returned to their own individual’s storage boxes. the modern sample consists of 142 second lower molars. it was registered by one of the authors (evl) on patients attending the school of endodontics of the universidad autónoma de yucatán (uady) for treatment during the fall semester of 2007. in this dental series, the form of the canal could be assessed visually from the occlusal surface (fig. 3). x-rays were performed for every subject to provide additional information on the root morphology, even though this set of data could not be used directly in the present study. patients receiving treatment at the school of endodontics of the uady usually come from low income sectors of society. relying on the subject’s patient records, they are all of native origin and even though most of them were born in the town, their parents commonly originated in villages in northern yucatán. despite admixture, which makes any direct comparison to prehispanic series problematic, this sample is largely representative of the natives’ genetic background. results among the 48 archeological roots under study, 17 were fused, constituting 35% of the total. radiographic analysis revealed that 15 out of 16 individuals possessed a c-shape morphology in at least some parts of their root canal. one tooth was excluded because the x-ray did not permit inspection of the form of its chamber. the resulting ratio corresponds to 32% of the overall sample (15/47). the modern cohort represents a 29% of second lower molars with a c-shape canal (42/142). the difference between the archeological and modern sample is not significant (chi-square = 0.014; p = 0.905) (table 1). as mentioned, no reliable information is available on the frequency of the one-rooted molar in the modern sample. we can assume that at least 42 out of 142 teeth were single-rooted; however, we cannot rule out the possibility that not all the one-rooted molars presented the c-shape. at the same time, two partly fused roots (forming a c-shape canal) may diverge towards the apical end. in anthropological terms, when the root is separated for at least one third of its length, it is considered as two roots. discussion genetic admixture (gene flow) is one of the reasons for changes in trait frequencies, and dental attributes are no exception. in opposition to other populations, like the caribbean tainos, who suffered a profound demographic collapse that led to its extinction within fig. 1. archeological example of a second mandibular molar from northern yucatan, dated to the classic period, which may possess a c-canal. fig. 2. x-ray image of the pulp chamber in an archeological second mandibular molar. the c-shape canal can be appreciated from the apical surface. c-shape molar root canals 48 few decades after the conquest (rouse, 1963; moya-pons, 1982), the maya became an integrated part of the newly formed, multi-ethnic society. the genetic admixture that occurred in yucatan as a natural consequence of the european conquest and introduction of african slaves surely had an impact in the gene pool in the region. here, demic movement also could have led to noticeable changes in the patterns of dental morphology. jacobi (2000) reported that the greater morphological distance between historic tipu and historic lamanai in belize was likely the consequence of a major admixture of mayas from northern yucatán fleeing to lamanai. the present study has centered on just two traits. clearly, it will be necessary to inspect a broader set of dental morphological traits in order to assess the extent to which admixture and time have modified the genetic structure of the modern maya population compared to their prehispanic status. this will be the goal of future studies. single-rooted second mandibular molars are very common in maya populations, slightly less common in europeans, and they appear to be rare in africans (scott and turner, 1997). since the frequency of fused roots in european groups is slightly lower than in mesoamerican ones, admixture might not have led to profound changes in the modern sample. the frequency is very much lower in africans (scott and turner, 1997). specifically for sub-saharan regions, from which the initial forced migration into the new world started in the 16th century ad, irish (1997) reported a value of 7%. even though african populations are considered to be the third root of the modern mexican population (tiesler et al., 2008), their genetic contribution may not have been large enough to produce noticeable changes, at least not in the yucatan region that has experienced a lower presence of african descendents than in neighboring states. conversely, the distribution in canal shapes differs significantly between the maya and old world groups (europe and africa). c-shape root canals appear at comparable frequencies in the modern and prehispanic yucatecan population, while being uncommon in old world groups (jafarzaed and wu, 2007). as a result of admixture, we were initially expecting a reduced frequency of “c” canals in the modern sample when comparing it to the prehispanic series. it is puzzling, instead, that the frequencies are very much alike. the form of the root canal is listed among dental anatomical anomalies (jerome and hanlon, 2007) and, at least until now, it does not seem to have specific evolutionary implications like other morphological traits that have been associated with dental reduction. yet, the persistence of single-rooted second molars and, notably, the c-shape pulpal chamber in the modern series under study might indicate a genetic (or morphological) stability of this feature. even though we stress the fact that a single trait is not sufficient to assess the extent of admixture, the persistence of this feature can be indicative of a persistent homogeneous composition of the modern maya population in northern yucatan. much remains to be done. from a joint anthropological and clinical perspective, the strong correlation between root form and canal morphology in the prehispanic sample might be instrumental in understanding the occurrence of these traits in modern populations. the endodontic literature (see jafarzaed and wu’s review, 2007) does not report the ethnic affiliation of those samples with low occurrence of c-shape canal. given the extensive information on the c-shape canal in asian peoples and the relative paucity in the other continents, table 1. counts and frequencies of c-shape canals and single-rooted second mandibular molars frequency c-shape c-shape sample total one-root one-root count frequency prehispanic 48 17 35.4% 15 31.9%† modern 142 ?? ?? 42 29.4% †one single-rooted molar could not be scored for canal form. fig. 3. occlusal view of a c-shape root canal in a modern patient before being treated at the school of endodontics, uady. mesial is to the right of the picture, and buccal is to the top. a. cucina et al. 49 further studies will shed light on this trait within the broader mesoamerican sphere and in european and african groups. acknowledgements we are grateful to thelma sierra sosa, xcambó archaeological project, and agustín peña castillo, noh bec/el escondidio archaeological project, for the archeological materials scrutinized in this study. literature cited cucina a, tiesler v, wrobel g. 2005. afinidades biológicas y dinámicas poblacionales mayas desde el clásico hasta el periodo colonial. los investigadores de la cultura maya 13: 559-567. gulabivala k, aung th., alavi a, ng yl. 2001. root and canal morphology of burmese mandibular molars. int endod j 34:359-370. haddad gy, nehme wb., ounsi hf. 1999. diagnosis, classification and frequency of c-shape canals in mandibular second molars in the lebanese population. j endod 25:268-271. irish jd. 1997. characteristic highand low-frequency dental traits in sub-saharan african populations. am j phys anthropol 102:455-467. jabobi k. 2000. last rites for the tipu maya: genetic structuring in a colonial cemetery. tuscaloosa: university of alabama press. jafarzadeh h, wu yn. 2007. the c-shaped root canal configuration: a review. j endodont 33:517-523. jerome ce, hanlon rj. 2007 dental anatomical anomalies in asians and pacific islanders. cda journal 35:631636. jin gc, lee sj, roh bd. 2006. anatomical study of cshape canals in mandibular second molars by analysis of computed tomography. j endodont 32:10-13. moya-pons f. 1982. los trabajadores indígenas y la estructura social en la española en 1514. boletín del museo del hombre dominicano 17:119-133. rouse i. 1963. the arawak. in: steward jh, editor. handbook of south american indians. vol 4. new cork: copper square publishers, p 507-546. scott gr, turner cg ii. 1997. the anthropology of modern human teeth. cambridge: cambridge university press. seo ms, park ds. 2004. c-shape root canals of mandibular second molars in a korean population: clinical observation and in vitro analysis. int endod j 37:139-144. tiesler v, zabala p, cucina a, editors. 2008. encounters at the edge of the sea. european, maya and african founders of campeche, mexico. gainesville: university press of florida. turner cg ii. 1990. major features of sundadonty and sinodonty, including suggestions about east asian microevolution, population history and late pleistocene relationships with australian aboriginals. am j phys anthropol 82:295-317. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, p 13-31. yang zp, yang sf, lin yc, shay jc, chi cy. 1988. c-shape root canals in mandibular second molars in a chinese population. endod dent traumatol 4:160-163. wrobel gd. 2004. metric and non-metric dental variation among the ancient maya of northern belize. ph.d. dissertation, university of indiana, indiana. c-shape molar root canals harris and couch 2006.6 87 human tooth crown dimensions exhibit little sexual dimorphism, which detracts for their usefulness for sex determination (ditch and rose, 1972; de vito and saunders, 1990). garn et al. (1967) showed that sexual dimorphism in a sample of american whites is only on the order of 3-5%, making them substantially less dimorphic than any of the other higher primates (e.g., swindler, 2002; koppe and swindler, 2004). the canines characteristically are the most dimorphic (ca. 6%), notably their buccolingual widths. sexual dimorphism in tooth size is useful in forensic settings (teschler-nicola and prossinger, 1998) and also in archeological settings when the more informative skeletal elements are immature or absent (krogman and iscan, 1986; ubelaker, 1999). that sex differences occur at all in the primary and permanent teeth is of interest because they depend on hormonal differences that preferentially develop size and shape in one sex over the other well before the onset of steroid-mediated adolescence (tanner et al., 1959; manning, 2002). we have collected incisor crown and root dimensions from a contemporary sample of american whites, and the purpose of this paper is to assess the relative sexual discriminating effectiveness of these crown and root variables. materials and methods incisor dimensions were obtained from standardized periapical radiographs using a computer assisted measurement system. data were collected from 148 adolescent american white adolescents (57 males, 91 the relative sexual dimorphism of human incisor crown and root dimensions edward f. harris* and w. max couch, jr. department of orthodontics, university of tennessee, memphis, tn 38163 abstract: teeth are unusual structures in that their dimensions are sexually dimorphic even though they form early in life, several years before steroid-mediated adolescence. these size differences make teeth attractive as indicators of a specimen’s sex. alternatively, the magnitude of sexual dimorphism in humans is low, so there is considerable overlap in sizes between the two sexes. prior studies suggest that tooth root dimensions are more dimorphic than crown dimensions, so roots would be more useful for sex determination. to explore this, we measured the four incisor tooth types from standardized periapical radiographs in a sample (n = 148) of living american white adolescents. root lengths are somewhat more dimorphic than crown sizes in this sample (ca. 6% vs. 2%), and this translates into somewhat higher discriminatory power. the hindrance, however, is that all crown and root sizes are positively intercorrelated, so there is effectively just one dentition-wide axis of “tooth size” variation. statistically, at least for these incisor tooth types, there is no added discriminatory power in the crown sizes once root dimensions have been accounted for, though the addition of data from other tooth types might improve discrimination somewhat. dental anthropology 2006;19(3):87-95. females). these were healthy, phenotypically normal teenagers (mean age 14 years). all of the teeth were caries-free, and none had been treated orthodontically, which typically reduces root length due to external apical root resorption (brezniak and wasserstein, 1993a,b). subjects were old enough to ensure root apexification, which is completed for the incisors around 10 years of age (harris and mckee, 1990). radiographs had been taken by an experienced dentist using a long-cone paralleling technique. teeth with rotations or angulations affecting tooth-to film orientations were omitted from analysis. radiographs give a proper measure of crown height since the cementoenamel junction is not obscured by the gingiva (cf. rhee and nahm, 2000). radiographs were digitized at 1,200 dpi and 256greyscale. sigmascan 5.0 (spss inc., chicago, il) was used to obtain crown and root dimensions, which were corrected for magnification prior to statistical analysis. the screen image of each tooth was magnified severalfold, which enhances landmark location but does not affect the dimensions obtained. the tooth with better image quality and alignment was chosen from each left-right pair. if there was no difference, the tooth in the left quadrant was analyzed, so sample sizes are of individuals, not teeth. *correspondence to: edward f. harris, department of orthodontics, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu 88 present study, the average of these two distances was used as root length. this distance was subtracted on an individual basis from tooth length to yield crown height. in sum, tooth length equals crown height plus root length. sexual dimorphism was assessed statistically using factorial analysis of variance (winer et al., 1991) and stepwise multivariate discriminant functions analysis (cooley and lohnes, 1971). principal components analysis (gorsuch, 1983) was performed to evaluate the statistical associations among the variables. statistics were calculated using the jmp software package (sas institute inc., cary, nc). results tooth dimensions of the four incisor tooth types, mesiodistal crown diameter of just the upper central incisor (u1) exhibits table 1. descriptive incisor dimensions, by sex, and tests for sexual dimorphism1 males females % sex adjusted analysis of variance tooth n x sd sem n x sd sem dimorphism r2 % f-ratio p value crown width u1 57 9.23 0.81 0.11 91 8.91 0.59 0.06 3.69 4.61 8.10 0.0051 u2 55 6.98 0.60 0.08 90 6.90 0.62 0.06 1.15 (-0.30)# 0.57 0.4497 l1 56 5.41 0.46 0.06 91 5.32 0.40 0.04 1.82 0.54 1.79 0.1828 l2 57 6.07 0.51 0.07 90 5.97 0.39 0.04 1.72 0.64 1.93 0.1666 tooth length u1 57 26.36 2.49 0.33 91 25.21 2.14 0.22 4.56 5.11 8.91 0.0033 u2 56 25.15 2.42 0.32 90 23.78 1.95 0.21 5.76 8.29 14.11 0.0002 l1 56 22.48 2.22 0.30 91 21.60 1.86 0.19 4.08 3.76 6.70 0.0106 l2 57 23.90 2.54 0.34 91 23.04 1.87 0.20 3.71 2.99 5.54 0.0199 crown height u1 57 8.40 1.00 0.13 91 8.24 0.86 0.09 1.93 0.04 1.06 0.3042 u2 56 7.45 0.86 0.11 90 7.14 0.69 0.07 4.31 3.10 5.64 0.0189 l1 56 7.05 1.01 0.14 91 7.14 0.86 0.09 -1.19 (-0.49)# 0.30 0.5874 l2 57 7.23 0.95 0.13 91 7.23 0.81 0.08 -0.01 (-0.69)# 0.00 0.9961 root length u1 57 17.95 1.98 0.26 91 16.96 1.86 0.20 5.84 5.45 9.47 0.0025 u2 56 17.70 1.99 0.27 90 16.64 1.75 0.18 6.38 6.70 11.41 0.0009 l1 56 15.43 1.70 0.23 91 14.47 1.38 0.14 6.68 8.34 14.29 0.0002 l2 57 16.67 1.96 0.26 91 15.81 1.39 0.15 5.41 5.55 9.64 0.0023 crown-root ratio u1 57 0.47 0.07 0.01 91 0.49 0.07 0.01 -3.95 1.19 2.77 0.0981 u2 56 0.42 0.06 0.01 90 0.43 0.06 0.01 -2.14 (-0.09)# 0.86 0.3542 l1 56 0.46 0.07 0.01 91 0.50 0.06 0.01 -7.17 5.98 10.29 0.0016 l2 57 0.44 0.06 0.01 91 0.46 0.05 0.01 -4.80 3.20 5.86 0.0168 1tooth codes are maxillary central (u1) and lateral (u2) incisor and mandibular central (l1) and lateral (l2) incisor. sexual dimorphism is calculated from the means, ((m-f)/f) times 100. ajusted r2 is the variation in the tooth dimension accounted for by sexual dimorphism (the independent variable) in the analysis of variance. #the r2 is close to zero, and the adjustment caused the estimate to be negative, though this has no statistical interpretation (and should be set to zero). full-mouth dental casts were taken along with the periapical radiographs, and we measured the maximum mesiodistal crown dimensions of the teeth using sliding calipers, which provide an absolute measure of tooth size as well an internal check of the radiographic method. four dimensions are evaluated here, (1) mesiodistal crown width, (2) overall tooth length, (3) crown height, and (4) root length. overall tooth length was measured from the root apex coronally to the mediolateral midpoint of the tooth’s incisal edge (fig. 1). root length—from the root apex to the cementoenamel junction (cej)—is not an invariant distance because the cej undulates around the tooth’s periphery (zeisz and nuckolls, 1949), with the cej higher (more occlusal) on the tooth’s mesial and distal aspects than labially or lingually. we measured the straight-line distance from the root apex separately to the mesial and the distal margins of the cej. for the e. f. harris and w. m. couch 89 table 2. matrix of pearson correlation coefficients for the 16 incisor dimensions studied1 u1 u2 l1 l2 u1 u2 l1 l2 u1 u2 l1 l2 u1 u2 l1 l2 cw cw cw cw tl tl tl tl ch ch ch ch rl rl rl rl u1 cw 1.00 0.55 0.62 0.58 0.35 0.32 0.43 0.44 0.45 0.35 0.35 0.39 0.21 0.23 0.35 0.36 u2 cw 0.55 1.00 0.52 0.54 0.27 0.34 0.19 0.22 0.29 0.38 0.23 0.32 0.19 0.23 0.11 0.11 l1 cw 0.62 0.52 1.00 0.68 0.27 0.23 0.48 0.44 0.41 0.31 0.48 0.42 0.13 0.14 0.34 0.34 l2 cw 0.58 0.54 0.68 1.00 0.21 0.18 0.38 0.38 0.31 0.26 0.44 0.43 0.11 0.11 0.23 0.27 u1 tl 0.35 0.27 0.27 0.21 1.00 0.67 0.51 0.51 0.56 0.38 0.26 0.33 0.93 0.62 0.51 0.49 u2 tl 0.32 0.34 0.23 0.18 0.67 1.00 0.54 0.53 0.35 0.51 0.23 0.32 0.64 0.94 0.56 0.51 l1 tl 0.43 0.19 0.48 0.38 0.51 0.54 1.00 0.88 0.36 0.26 0.67 0.59 0.45 0.51 0.90 0.82 l2 tl 0.44 0.22 0.44 0.38 0.51 0.53 0.88 1.00 0.35 0.32 0.62 0.67 0.45 0.48 0.78 0.93 u1 ch 0.45 0.29 0.41 0.31 0.56 0.35 0.36 0.35 1.00 0.48 0.46 0.44 0.21 0.21 0.19 0.22 u2 ch 0.35 0.38 0.31 0.26 0.38 0.51 0.26 0.32 0.48 1.00 0.32 0.38 0.24 0.18 0.15 0.22 l1 ch 0.35 0.23 0.48 0.44 0.26 0.23 0.67 0.62 0.46 0.32 1.00 0.77 0.10 0.13 0.28 0.40 l2 ch 0.39 0.32 0.42 0.43 0.33 0.32 0.59 0.67 0.44 0.38 0.77 1.00 0.19 0.22 0.31 0.35 u1 rl 0.21 0.19 0.13 0.11 0.93 0.64 0.45 0.45 0.21 0.24 0.10 0.19 1.00 0.63 0.51 0.48 u2 rl 0.23 0.23 0.14 0.11 0.62 0.94 0.51 0.48 0.21 0.18 0.13 0.22 0.63 1.00 0.58 0.50 l1 rl 0.35 0.11 0.34 0.23 0.51 0.56 0.90 0.78 0.19 0.15 0.28 0.31 0.51 0.58 1.00 0.82 l2 rl 0.36 0.11 0.34 0.27 0.49 0.51 0.82 0.93 0.22 0.22 0.40 0.35 0.48 0.50 0.82 1.00 1variable codes are crown width (cw), tooth length (tl), crown height (ch), and root length (rl). sample size was 148 individuals for all correlations, so coefficients above 0.16 are statistically significant (p < 0.05; rohlf and sokal, 1981). table 3. results of principal components analysis on 16 incisor dimensions, without rotation eigenvectors tooth i ii iii iv crown width u1 0.061 0.044 0.038 0.177 u2 0.038 -0.019 -0.010 0.198 l1 0.034 0.048 0.029 0.112 l2 0.028 0.042 0.029 0.116 tooth length u1 0.418 -0.405 0.497 0.108 u2 0.382 -0.276 -0.535 0.248 l1 0.367 0.409 0.027 0.000 l2 0.371 0.423 0.073 0.065 crown height u1 0.083 -0.015 0.144 0.427 u2 0.063 -0.026 0.006 0.313 l1 0.087 0.182 0.094 0.361 l2 0.086 0.121 0.063 0.330 root length u1 0.335 -0.390 0.353 -0.320 u2 0.319 -0.250 -0.542 -0.065 l1 0.280 0.228 -0.067 -0.361 l2 0.285 0.302 0.010 -0.265 eigenvalue 21.164 5.475 2.785 1.836 percent 61.847 16.000 8.138 5.365 cumulative percent 61.847 77.847 85.986 91.351 fig. 1. labial view of a maxillary right central incisor showing measurements of root length determined separately on the medial and lateral aspects (from root apex to cej) and tooth length (from root apex to midpoint of incisal edge). crown height was operationalized as tooth length minus root length (i.e., average of medial and lateral distances), which yields a longer root length (and shorter crown height) than if the labial or lingual level of the cej had been used. crown and root sexual dimorphism mediallateral 90 significant sexual dimorphism (table 1). percentagewise, mean size for males is only 1-2% larger than for females. the other crown dimension assessed here, crown height, comparably exhibits little sexual dimorphism. just the mean size difference for u2 is significant statistically (a 4% difference), and crown heights of the mandibular incisors are virtually identical in the two sexes. it seems noteworthy that overall tooth lengths of all four incisors are appreciably more dimorphic. all four anova tests are significant (table 1). percent sexual dimorphism is lower but not trivial in the mandible (ca. 3%) and higher (ca. 5 to 8%) in the upper arch. this greater sexual dimorphism likewise is reflected in the coefficients of determination (r2) that can be read as the percentage of the variation in tooth length accounted for in the statistical sense by “sex.” percentages are lower for the two mandibular incisor types than in the maxilla, or, perhaps more correctly, the maxillary lateral incisor tooth length is comparatively highly dimorphic (r2 = 14%). it is evident that tooth length is composed of crown height and root length and, since sex differences in crown height are minor, most of the dimorphism obviously is due to sex differences in root length (table 1). indeed, sexual dimorphism in incisor root lengths is in the range of 5 to 8%, which is noticeably higher than for crown widths or heights. also, unlike crown dimensions, percentage sex differences are not smaller for the mandibular root dimensions. crown-root ratios incisor crown-root ratios (table 1) were here assessed for completeness. the ratio is simply crown height divided by root length, so the larger the ratio the more crown height contributes to overall tooth length. ratios are 50% or less, showing that incisor root lengths characteristically are more than twice their crown heights. mean crown-root ratios are slightly larger in the mandible because the mandibular root lengths are proportionately shorter. sexual dimorphism for these ratios is trivial in the maxillary incisors, whereas both tests are significant for the mandibular incisor types. these mandibular differences are due to longer roots in males (whereas the crown heights are very similar in men and women). correlation matrix several studies have shown that tooth crown diameters are positively intercorrelated (reviewed, e.g., in henderson, 1975), and garn et al. (1978a) showed that root lengths within individuals likewise covary in a positive fashion. these expectations are evident in the present data (table 2) where all 120 pairwise correlations are positive and most are significantly different from zero statistically. given the uniform sample size of 148 cases, correlations above 0.16 are significant (p < 0.05) and those above 0.21 are highly significant (p < 0.01). scanning the matrix, the weakest correlations are between crown widths and root lengths, and the strongest are between tooth lengths and root lengths. these latter are predictable, however, because root length is the major constituent of tooth length. pearson and davin (1924; also see solow, 1966) term these sorts of correlations of a dimension plus part of itself “spurious” in the sense that they are correlated simply because of their geometric association, which need not be biological. ideally, one would like to find statistically independent axes of variation so that the sexual dimorphism exhibited by some tooth dimensions is not duplicative of that of other dimensions. separate “axes” of variation would provide greater statistical power for discriminating between the sexes using multiple tooth dimensions. given the consistently positive, generally high correlations here (table 2) suggests that there is effectively just a single statistical (and, by inference, biological) axis of sexual dimorphism. principal components analysis pca (gorsuch, 1983) was used to assess the relationships among the crown and root dimensions. four dimensions for each of the four incisor tooth types were used in the analysis, namely (1) crown width, (2) tooth length, (3) crown height, and (4) root length. four components were extracted with eigenvalues exceeding table 4. descriptive statistics for the principal components scores and tests for sexual dimorphism1 males females adjusted analysis of variance axis n x sd sem n x sd sem r2 % f-ratio p value pc i 54 1.582 4.886 0.665 89 -0.960 4.160 0.441 6.563 10.97 0.0012 pc ii 54 -0.136 2.537 0.345 89 0.082 2.223 0.236 (-0.503)# 0.29 0.5912 pc iii 54 -0.152 1.792 0.244 89 0.092 1.593 0.169 (-0.198)# 0.72 0.3977 pc iv 54 -0.195 1.446 0.197 89 0.118 1.291 0.137 0.562 1.80 0.1815 1variable codes are principal component scores for axes i through iv. #the r2 is close to zero, and the adjustment caused the estimate to be negative, though this has no statistical interpretation (and should be set to zero). e. f. harris and w. m. couch 91 u 1 c w u 2 c w l 1 c w l 2 c w u 1 t l u 2 t l l 1 t l l 2 t l u 1 c h u 2 c h l 1 c h l 2 c h u 1 r l u 2 r l l 1 r l l 2 r l 0.0 0.1 0.2 0.3 0.4 0.5 v a ri a b le l o a d in g s u 1 c w u 2 c w l 1 c w l 2 c w u 1 t l u 2 t l l 1 t l l 2 t l u 1 c h u 2 c h l 1 c h l 2 c h u 1 r l u 2 r l l 1 r l l 2 r l -0.5 -0.3 0.0 0.3 0.5 v a ri a b le l o a d in g s u 1 c w u 2 c w l 1 c w l 2 c w u 1 t l u 2 t l l 1 t l l 2 t l u 1 c h u 2 c h l 1 c h l 2 c h u 1 r l u 2 r l l 1 r l l 2 r l -0.6 -0.3 0.0 0.3 0.6 v a ri a b le l o a d in g s u 1 c w u 2 c w l 1 c w l 2 c w u 1 t l u 2 t l l 1 t l l 2 t l u 1 c h u 2 c h l 1 c h l 2 c h u 1 r l u 2 r l l 1 r l l 2 r l -0.4 -0.1 0.2 0.5 v a ri a b le l o a d in g s pc i pc ii pc iii pc iv fig. 2. plots of the variable weights on the first four principal components extracted from the covariance matrix of 16 crown and root dimensions. these “weights” of variables with each canonical axis can be interpreted as the correlation coefficient of the variables with the axis. crown and root sexual dimorphism 92 one (kaiser, 1970), and these were evaluated without matrix rotation (table 3). these four axes account for most (91%) of the variation, and, within these, just the first axis is responsible for most (62%) of the total variance. pc i is controlled by tooth length, with slightly higher weightings on the two maxillary dimensions (fig. 2). probably because root lengths are major constituents of tooth length (fig. 1), root lengths also have comparatively high weights on this component. pc ii reflects the high loadings of tooth lengths and root lengths, but here there are polarities (opposite signs) for variables in the maxilla and the mandible. as with the first component, crown widths and heights have only minor loadings (correlation coefficients) with pc ii. pc iii is a further orthogonal axis of variation for root length and, by association, tooth length. here just the maxillary variables exhibit high loadings, with polarities between the central and lateral incisors. in other words, having accounted for the variances of pc i and ii, the remaining major axis of variation is a contrast between root lengths of the two maxillary incisor types. highly weighted variables for pc iv are restricted to crown heights and root lengths (fig. 2). within a variable (crown height or root length), all four weights are of the same sign. when tested for sexual dimorphism (table 4), pc i scores, which depend primarily on root lengths, are highly significant. in contrast, none of the other three axes seems to be of any value for sex discrimination. discriminant analysis when the eight crown size variables (4 widths, 4 heights) were subjected to stepwise linear discriminant function analysis, just one variable—crown width of u1—was significantly predictive. correct allocation was 47% overall, though somewhat higher in girls (56%) than boys (37%). when the other eight variables were analyzed (4 tooth lengths, 4 root lengths), again there was just one significant predictor because of the considerable 0.00 0.25 0.50 0.75 1.00 p ro b a b il it y o f c o rr e ct a ss ig n m e n t 91 females 51 (56%) correctly assigned 57 males 21 (37%) correctly assigned 0.00 0.25 0.50 0.75 1.00 p ro b a b il it y o f c o rr e ct a ss ig n m e n t 91 females 58 (64%) correctly assigned 57 males 31 (54%) correctly assigned maxillary i1 crown width mandibular i1 root length fig. 3. sequenced arrays of the probabilities of group assignment. probabilities above 50% are the cases correctly assigned; cases with probabilities below 50% were allocated to the wrong sex. the height of the symbol above the 0.5 line is a measure of how confident the researcher can be that the case is correctly classified. the shallow slop of the distributions illustrates the weak sexual dimorphism even of these selected variables. top. arrays using u1 crown width, which is the one statistically significant crown size predictor of sex from among the 8 tested. bottom. arrays using mandibular i1 root length, which is the one significant root size predictor of sex in this sample from among the 8 tested. e. f. harris and w. m. couch 93 statistical redundancy of these dimensions. here, mandibular central incisor (l1) root length was most discriminating, with 60% correct assignment (54% for males; 64% for females). this is an improvement over using crown widths alone, but the increase in correct assignment (60% vs. 49%) is modest. one can see from the very gradual slope of probabilities of correct assignment (fig. 3) that there is considerable overlap in crown and in root dimensions between the two sexes. we supposed that there would be enough statistical independence between crown and root dimensions that they could be used in combination to improve sex determination. this was not the case. once the greater dimorphism of root length was entered (specifically, inclusion of l1 root length at step 1) and statistics of the other variables were adjusted to account for root length, none of the other dimensions had significant independent power to be added. with hindsight, this is because all 16 of the variables studied here are positively intercorrelated, and even the weakest associations (between crown widths and root lengths) are still on the order of 0.1 to 0.2. discussion tooth root size and morphology have been studied far less than crown size (e.g., kovacs, 1971; thomas, 1995), largely because of their inaccessibility and, additionally, in archeological specimens, their comparative fragility. so too, little is known about the genetic control of root size and morphology. most root formation occurs prior to tooth emergence (carlson, 1944), which may be protective against forces of mastication until teeth are in function. unlike enamel, a root’s configuration is subject to surface remodeling. root resorption can be instigated with orthodontic forces (harris, 2000) or with jiggling forces that are common consequences of pathological loss of supporting crestal bone (nyman et al., 1978; harris et al., 1993). the accretion of cementum, in contrast, increases root dimensions in an age-progressive manner (wittwerbackofen et al., 2004), though the annual depositions are too small to be visualized on conventional radiographs. cementum accumulation typically is thickest in the bifurcations of multirooted teeth, though hypercementosis occasionally occurs periapically (e.g., halstead and hoard, 1991). the normal age-progressive periapical accumulation of cementum needs to be studied in more detail; researchers have reported on an increase in root length—supposedly by cementum apposition—as an age-progressive event. most such studies have been cross-sectional (levers and darling, 1983; whittaker et al., 1990), though there is some longitudinal evidence for root lengthening with age (bishara et al., 1999). the prime focus in the present study was to test whether root lengths exhibit greater sexual dimorphism than crown dimensions, where sex differences are too subtle to be definitive in most cases (ditch and rose, 1972; kieser and groeneveld, 1989). precisely because sexual dimorphism is modest in humans, most studies that have developed discriminant functions capitalize on sex differences specific to their own sample; applications to other groups generally exhibit much weaker frequencies of correct sex assignment. the problem is intrinsic to the crown size data, not to sophistication of the statistical techniques. there are two synergistic problems, (1) there is little sexual dimorphism (the canines, especially buccolingually, seem to be the most dimorphic; sciulli et al., 1977) and (2) even though teeth are numerous within a person, crown sizes all are significantly, positively intercorrelated, so there are few axes of novel information to exploit (e.g., moorrees and reed, 1964; potter et al., 1968; harris and bailit, 1988); the sexual dimorphism seen among crown dimensions is statistically redundant. these observations seem to have motivated garn and coworkers (1979) and others to look for independent axes of variation. tooth roots seem to offer two advantages here: (1) the dimensions are at least partially uncoupled from crown size (fig. 2), so the data are not repetitive (statistically redundant) with crown dimensions, and (2) root lengths are a bit more dimorphic than crown dimensions (table 1). the present study has clear precedents in the work of stanley garn and colleagues (1978a,b, 1979) who measured root lengths in a sample of living american white teenagers using 45° oblique-jaw radiographs. they measured five mandibular tooth types (c, p1, p2, m1, m2) omitting the incisors that are distorted in this radiographic view. while their methodological details differ from ours, there are some key similarities. one, we examined different teeth than garn’s group, but our intertooth correlations (table 2) for tooth lengths are in the same range, about 0.5 to 0.6, and the correlations within an arch are higher than between arches. two, the correlations between crown size (here we tested mesiodistal incisor crown widths) and root lengths are low (ca. 0.1 to 0.2) but consistently positive. garn et al. (1978b) found the same low level of crown-root integration. garn and coworkers (1979) tested the sex discriminatory power of numerous combinations of crown and root dimensions. scrutiny of their presentation shows, however, that they made no effort to show that each variable in each discriminant function contributed significant statistically information. alternatively, the simple addition of more variables typically will improve discrimination of individuals in the sample used to generate the formulae (discriminant functions) because using more variables capitalizes on variation unique to that sample. unfortunately, amassing variables (1) does not improve the statistical significance of the predictive equation and (2) detracts from the generalizability of the results to other samples (kieser and groeneveld, 1989). crown and root sexual dimorphism 94 in other words, “percentage correct allocation” should not be the driving criterion for developing discriminant functions because that criterion commonly is specific to the sample used to develop the functions—that criterion promotes exploiting male-female differences specific to that sample, not to sex differences in size relationships at large. tooth roots serve several functions (shafer et al., 1983), including the important function of transmitting the forces of occlusion to the supporting alveolar bone. given the significantly larger bite forces in males than females, especially after the onset of puberty (e.g., bakke et al., 1990; julien et al., 1996), the tendency for larger roots (with larger surface areas) in men probably is adaptive. as garn noted (1978b, p 636): it is impressive that the crowns of permanent teeth that begin to form by the second trimester of prenatal life and that complete their sizeattainment in the second to fifth year of postnatal life thus “anticipate” the length of still-to-becompleted roots by 10 years or more. conclusions this study of incisor crown-root dimensions in a contemporary american white sample shows that root lengths are somewhat more sexually dimorphic than crown dimensions and, thus, are somewhat more useful for sex determination. the statistical associations are higher among crown dimensions than between crowns and roots, but all correlations are positive. our discriminant function analysis (that relied just on incisor tooth types) does not support the supposition that combinations of crown and root dimensions are any more useful for sex determination than root dimensions alone—because the dimensions all seem to reflect the same statistical information. perhaps the use of more tooth types, notably the canine, would somewhat improve correct sex assignment from tooth dimensions. literature cited bakke m, holm b, jensen bl, michler l, moller e. 1990. unilateral, isometric bite force in 8-68-year-old women and men related to occlusal factors. scand j dent res 98:149-158. bishara se, vonwald l, jakobsen jr. 1999. changes in root length from early to 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2006.1 1 torus mandibularis is a non-metric trait found in varying frequencies among human populations past and present, and as such is commonly recorded along with a battery of other such traits during the archeological assessment of skeletal remains. nonmetric traits are largely used in analyses of biological distance within and among archeological samples due to the assumption of a high heredity quotient in their occurrence. berry and berry (1967) established the utility of several skeletodental traits in biodistance analyses, but several traits commonly included in such analyses lack substantive evidence of genetic involvement. torus mandibularis was chosen to test the utility of the trait in establishing biological relationships specifically because of the debate surrounding its etiology. lacking a clear pattern of genetic inheritance, the trait has been seen by a number of researchers to relate instead to the osteological response of the masticatory complex to mechanical stresses. there has been nearly 100 years of contention as to whether the trait might represent a phenomenon related either to genetic heritability on a population level or to functional stress. this study was intended to provide direct evidence of either a correlation between occurrence and functional stresses on the masticatory complex, or a conclusive lack of correlation. additionally, the degree to which this data set corresponds to other researchers’ assessments of population-level variation is addressed. a total of 498 individuals from 8 archeological collections was assessed here on factors that have been posited to play a role in torus mandibularis: etiology and bioarcheological utility brenna hassett university college london institute of archaeology, london, united kingdom abstract: torus mandibularis is a non-metric trait commonly recorded in bioarcheological investigation and often included in the battery of non-metric traits used to analyse biological distance among populations. however, there is considerable debate regarding the etiology of the trait, with genetic and environmental factors both having been posited as the primary factor in torus development. this study of 498 individuals, drawn from eight archeological samples, investigates the variation in torus frequency in different groups as defined by sample, age, sex, and measures of functional stress. frequencies varied significantly among both samples and dental attrition categories, supporting the idea that mandibular tori are a threshold trait, influenced by both genetic and environmental factors. results of this study suggest the utility of mandibular tori in bioarchaeology may lie outside of biodistance analyses that rely on the high heritability quotient of non-metric traits to establish population distances. dental anthropology 2006;19:1-14. correspondence to: brenna hassett, 5 oakworth court, 160 nelson road, london n8 9rp, uk e-mail: brennaryan_1@hotmail.com torus development, namely population group, age, sex, and evidence of functional stress. torus mandibularis is recognized as a bony ridge or series of bony nodules or lumps appearing on the lingual surface of the alveolar margin of the mandible, generally in the premolar region (hauser and destefano, 1989). these tori may be completely absent or present in varying degrees, and may present a variety of forms. mandibular tori are not associated with any pathological condition and can be easily distinguished from instances where osteological activity is the result of a pathological condition causing abnormal growth, such as trauma or tumor. torus mandibularis is generally manifested bilaterally, though it may be present just on one side of the mandible. there is often a degree of asymmetry between sides, with the right side most commonly presenting a more pronounced torus than the left (haugen, 1990; seah, 1995). etiological debate the question of etiology is vital in assessing whether use of oral tori in biodistance analysis is appropriate. if tori are assumed to be solely under genetic control, then mandibular exostoses are accepted as useful estimators of population distance along with the other traits commonly used as part of the battery of non-metric traits established by berry and berry (1967). if, however, environmental factors play a larger role in determining trait frequency, then their use as estimators of population affinity is not acceptable. the relative importance of environmental compared to genetic factors in the editor’s note: ms. hassett’s paper was awarded first prize for 2005 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. 2 development of facial tori has been widely debated, with arguments for the functional basis of tori being contradicted by arguments for a higher genetic factor in increasing tori incidence. the trend has been to observe an increasing role for genetic causality, but it remains to be seen whether genetic inheritance fully explains the development of mandibular exostoses. the most recent studies have suggested that the tori arise in response to both genetic and environmental factors (haugen, 1990; seah, 1995). there are several particular aspects of tori distribution that have served as foci for debate, and multiple hypotheses that have been constructed to address the significance of population, sex, age, evidence of functional stress, robusticity of mandible, symmetry, and trait interaction in the formation of the mandibular tori. multiple studies attempting to assess the heritability of torus mandibularis have been conducted, coming to divergent conclusions—autosomal recessive (krahl, 1949; alvessalo and kari, 1972), autosomal dominant (suzuki and sakai, 1960), or polygenetic in origin (johnson et al., 1965; sellevold, 1980)—that there is a strong argument against a simplistic assumption of genetic transmission of the trait. however, it has been commonly found to occur in family groupings, and children whose parents exhibited the trait were found to be more likely to exhibit the trait themselves in a study of modern thais (kerdpon and sirirungrojying, 1999). the explanation for these diverse findings may lie in the work undertaken by researchers to establish the heritability of non-metric traits in studies of mice and non-human primates. grüneberg (1963) established the concept of quasi-continuous variation in nonmetric traits, positing that the size or rate of formation of a given trait may be the inherited factor, which he demonstrated by using genetically isolated strains of mice. wright (1968) followed this by suggesting the idea of a “threshold” trait that appears only once a certain point determined by environmental factors has been crossed; what the individual inherits is a liability towards developing a trait which environmental factors act upon. berry and berry (1967) undertook to study the genetic origins of a large battery of non-metric traits in mice, and it is to this work that most researchers utilizing non-metric traits in estimating biological distance refer. observing the analogues of several human skeletal traits in generations of mice, they proposed that most of the human non-metric traits also originate from normal genetic variation. the degree to which the environment influences mandibular torus prevalence, and the degree to which genetic inheritance does, should be understood in order for this particular non-metric trait to be included in the battery of traits assembled by berry and berry (1967) commonly used to establish biological distance among populations. factors affecting this debate include the difference in age and sex. variation between age classes in tori frequency and degree of expression has not been found by all researchers (hauser and de stefano, 1989:9), but the largest studies suggest that there is some degree of variation (eggen, 1954; korey, 1980; haugen, 1990; jainkittivong and langlais, 2000; ruprecht et al., 2000). researchers have found in some cases that males are more likely to exhibit tori than females (haugen, 1990; seah, 1995; hjertstedt et al. 2001), whilst in others there is no significant sex difference (e.g., bernaba 1974), or that females have higher frequencies of tori (corruccini, 1974). a brief summation of the disparate results of some of these studies may be found in table 1. the consensus appears to suggest that there is some degree of sexual dimorphism (trinkaus, 1978; haugen, 1990; seah, 1995), but it is difficult to assess whether this difference is significant in a statistical sense, particularly in archeological samples where sample sizes may be small. variation in tori prevalence and expression with increasing evidence of functional stress to the masticatory complex has been the cornerstone of arguments for the primacy of environmental factors in the development of oral tori. proponents of this view suggest that differences among groups may be accounted for either entirely or partially by non-hereditary factors, in which case mandibular tori are unsuitable for assessing biological distance without consideration of complicating environmental factors. instead, they would be of greatest utility in assessing differences in environmental factors such as diet or parafunctional use of the jaws. patterns of dental attrition, as a result of masticatory hyperfunction related to diet or conditions such as bruxism, have been seen to co-occur with mandibular tori in a statistically significant way in several instances. this has not been a universal observation (e.g., scott et al., 1991). sirirungrojying and kerdpon (1999) found that torus mandibularis was significantly (p < 0.005) more common in dental patients suffering from temporomandibular disorder (tmd), perhaps due to high levels of parafunctional activity, such as clenching and grinding of the teeth (bruxism). this led them to suggest that torus mandibularis could be viewed as an early indication of risk for tmd. larsen (1997) also comments that the general robusticity of the masticatory complex may be closely correlated with the amount of stress placed on the jaws; for example, a smaller, more gracile jaw would be correlated with a softer diet. johnson (1959) studied the mechanical stress of the jaws in conjunction with bone histology. the conclusions of his research were published posthumously, however, and the specific details of his findings are not provided; there is just the supposition that tori may be interpreted from histologiy to be the result of functional stress (johnson, 1959). no subsequent study has found any evidence to support this hypothesis (haugen, 1990; seah, b. hassett � 1995). an earlier study by van den broek (1943), who had formerly supported the hypotheses of functional stress acting to produce the tori, investigated tori histology and found that the structure of the tori did not represent an obvious bony response to mechanical stress. the symmetry of mandibular torus formation has also been called on to account for trait etiology. ossenberg (1981) ascribes overall tori frequency to environmental factors, but maintains that the degree of expression and any resulting asymmetricality is a function of genetics. korey (1980) suggests that genetic factors would be more likely to act equally on both sides of the mandible. mcgrath et al. further emphasize the importance of assessing asymmetry in measuring non-metric traits, suggesting that asymmetrical development, insofar as it is correlated to environmental causes, may be a clue to an individual’s ability to buffer stress (mcgrath et al., 1984, p 401). another suggested explanation of the development of the tori is local inflammation of the periosteum, leading to torus formation (schreiner, 1935). this was followed by van den broek after his (1943) investigation of torus histology failed to support the hypothesis that the tori are laid down to strengthen the structural integrity of the jaw. little evidence has thus far been provided to further this hypothesis. hypotheses tested having examined previous approaches to understanding the etiology of torus mandibularis, several questions remain. of primary interest here is the suitability of this non-metric trait for use in biodistance analyses; that is, whether there is sufficient genetic control of the tori to warrant its use as a marker of family or population group membership. the prevailing opinion in the most recent summaries of the issue is that mandibular tori are a quasi-continuous or threshold trait (haugen, 1990; seah, 1995), having both a genetic and environmental component. if this is accurate, then questions arise concerning what degree of influence sample males(%) females (%) citation poundbury 16.3 10.9 farwell and molleson 1993 cannington 11 15 brothwell et al. 2000 ukranian 0.0 1.5 cesnys and kundruktova 1982a lapps 26.8 38.8 schreiner 1935 north american whites 6.5 8.1 corruccini 1974 eskimo 58.1 35.2 dodo and ishida 1987a canadian eskimo 85.3 80.0 dodo and ishida 1987a aleuts 71.7 75.9 dodo and ishida 1987a brazilian indians 0.5 0.5 bernaba 1977 blacks 6.1 6.2 corruccini 1974 japanese 26.7 33.3 mouri 1976a ainu 44.3 21.1 dodo and ishida 1987a iglooik eskimo 38.7 40.8 mayhall and mayhall 1971 hall beach eskimo 41.5 32.1 mayhall and mayhall 1971 norwegian 6.36 8.53 haugen 1990 acited in hauser and destefano (1996). table 1. frequencies of torus mandibularis in various groups, by sex sample n males females unknown location period chumash 47 19 23 6 california coast, channel islands prehistoric abingdon 103 39 43 21 oxfordshire, uk medieval cannington 101 47 37 3 somerset, uk dark ages and late roman (7-8th c. ad) spitalfields 100 48 31 12 london, uk 17th-19th century poundbury 71 29 32 9 dorchester, dorset, uk roman 4th c. ad hawara 50 28 17 5 hawara, fayum, egypt roman 2nd-3rd c. ad egypt 23 10 9 4 abydos, egypt preto dynastic period lachish 13 4 8 1 lachish, israel mixed bronze, iron age table 2. characteristics of the samples used in the study. torus mandibularis 4 each factor has on trait prevalence. to address these questions and the impact of the major factors on torus development posited by previous research, the following hypotheses have been formulated. firstly, if there is a genetic component to trait prevalence, different ethnic or population groups should show different frequencies of trait development. this does not, of course, rule out any environmental influence, but merely establishes the possibility that genetics could play a role. to firmly establish the genetic etiology of the tori would require a carefully controlled study covering generations, which was not feasible here. secondly, significant variation between the sexes would show that there is a level of sexual dimorphism to tori development. if the rates of sexual dimorphism differ significantly from sample to sample, this would indicate that the major force acting on dimorphism for these traits is environmental, rather than genetic, as the mode of genetic transmission of the trait is assumed to not vary between populations, while culturally differentiated sexual labor roles may differ. thirdly, variation between age groups in tori prevalence would reflect a difference in frequency caused by either progressive development of the exostoses or by a dynamic process related to functional stress. if the occlusal attrition and robusticity of the mandible are strongly correlated with age and tori prevalence, then the latter hypotheses may be supported. if there is little correlation between indicators of masticatory stress, age, and prevalence, then progressive development would be supported by significant variation between age classes. finally, the indications of masticatory hyperfunction—particularly tooth wear—would be greater in individuals with mandibular tori if masticatory hyperfunction is a large factor in determining tori prevalence. materials and methods the materials used in this study come from the large collection of human skeletal material held by the department of anthropology of the natural history museum of london. the collection comprises material from over 20,000 individuals, gathered throughout the 19th, 20th, and 21st centuries from archeological excavations, anthropological fieldwork, and donated private collections (r. kruzynski, pers. comm.). the larger coherent samples included here were largely archeological samples, groups that were spatially and chronologically limited to the time and location of excavated burials. the ideal sample size, based on both statistical and temporal concerns, was established as 100 individuals for each population. however, this was not possible in all cases. some samples were comprised of fewer than 100 individuals, such as the egypt group, which remains in the final analysis despite the smaller size in an effort to broaden the regional scope of the study. the lachish sample was dramatically limited by the disassociation of mandibles from crania and was not considered sufficient to be included as anything other than an ancillary note in the population-based analysis, though it is included in the overall analyses. a summary of the samples included here is given table 2. on the individual level, inclusion was dictated by several criteria. as mentioned above, and particularly in the case of the lachish sample, all groups were of course limited by the number of individuals with associated mandibles. additionally, inclusion occasionally depended on the level of preservation encountered, as the most fragmented remains could not be scored for all points of interest. in order to avoid biasing the samples in favor of more robust crania less likely to suffer a high degree of fragmentation, however, every effort was made to include both fragmented and non-fragmented remains where scores could be taken. exclusion of individuals only occurred where it was not possible to take the scores of presence or absence of the tori. for the collected data, a total of 41 measurements or scores were taken and used to create the final scores that are used in analysis. the aim behind the selection of these measurements was to provide standardized and, thus, easily comparable, data on age, sex, trait expression and frequency, mandibular thickness, temporomandibular joint remodeling, and tooth macrowear. where published figures on the samples investigated here were available, they were compared with the assessments of this study. age and sex assignments were established solely on cranial material due to the time constraints on the present study. assignments were analyzed against previous published results drawn from both cranial and postcranial material, and in the exceptional case of the spitalfields material, drawn from individuals of known age and sex. insufficient discrepancy was found to warrant any adjustment of my own assessments, and because a standardized method was applied to all samples under discussion, the study is certainly internally coherent. age and sex were established after the chicago standards (buikstra and ubelaker, 1990). not used here as a criteria for age estimation was the degree of dental attrition. attrition, or the wear on the occlusal (chewing) surface of teeth, progresses with age, though at variable rates and is commonly used to assess biological age among archeological samples (brothwell, 1986; hillson, 1996). samples may differ widely in their rates of attrition, as the amount of abrasive material in the diet and functional stress acting to wear the teeth differ among groups and even between the sexes (walker et al., 1997, p 174). lacking a comparable population with known age, sex, diet, and functional stresses, age estimates based on tooth attrition may be seriously distorted by a number of variables depending on the population in question. as attrition is also used here to examine the b. hassett 5 functional stresses placed on the masticatory complex, the age estimates garnered from scoring tooth wear were excluded. sutural closing of the cranium was used instead, though this method is rightfully criticized for its unreliability (masset, 1976). therefore, the age categories used here are very broad—young adult (17-34 years of age), adult (35-54 yr), and older adult (55+). this study counts trait presence in three categories, namely absent, unilateral, and bilateral. metric equivalents of these categories (measured as maximum tori breadth on the transverse plane) are delineated in 2 mm increments with less than 2 mm being “slight,” 2-4 mm “moderate,”and greater than 4 mm “pronounced.” examples of the slight and moderate categories are provided in figures 1 and 2. an example of the trait as it appears in a living individual can be found in figure 3. attrition was scored at the left first and second molars, both upper and lower, and the “edentulous” category represents individuals who had premortem loss of the teeth. remodeling activity at the temporomandibular joint (tmj) was assessed on morphological changes to the joint surface both on the mandibular and the temporal bones (e.g., excessive porosity, osteophyte activity). robusticity was of the mandible was assessed as the variable bodth after humphrey et al. (1999). the measurement is of mandibular body thickness, taken from the left side of the mandible by spreading calipers placed parallel to the occlusal plane at m1 in the center of the mandibular body. this measurement was seen to correlate strongly with overall metric measures of size in the mandible (humphrey et al., 1999). the presence of maxillary tori—a similar non-metric trait that is nearly identical to torus mandibularis in manner of expression and the degree of understanding regarding its etiology—was also recorded according to the same methodology as mandibular tori. as a second example of exostoses of the dental arch, this trait was considered likely to have similar factors affecting its torus mandibularis sample absent unilateral bilateral total chumash 47 1 48 lachish 13 13 hawara 43 1 6 50 cannington 65 2 24 91 abingdon 98 2 � 10� spitalfields 96 2 2 100 poundbury 56 5 9 70 egypt 20 1 2 2� total 438 13 47 498 1chi-square = 56.639; df = 14; p value < 0.000; chi square for unilateral and bilateral categories grouped as “present” = 41.348; df = 7; p value < 0.000. table 3. counts of unilateral and bilateral forms of torus mandibularis by sample1 fig. 1. example of slight expression of torus mandibularis in a skull (sk34) from cannington cemetery (courtesy natural history museum, london). fig. 2. example of moderate expression of torus mandibularis in a skull (sk112) from cannington cemetery (courtesy natural history museum, london). 6 development. there were two primary areas in which the functional stresses placed on the masticatory complex were assessed in this study. the best skeletal evidence of stresses associated with excessive chewing and/or grinding motions necessitated by either a tough diet or a pathological condition (i.e., bruxism) in an individual is found in morphological changes in the masticatory apparatus (eggen and natvig, 1986). representing these changes in the skeleton are, firstly, the degree of occlusal wear of the molar dentition of the upper and lower jaws, and, secondly, osteological activity in the tmj. analysis all of the data collected for this study were entered into a computerized database to facilitate statistical and comparative analysis. this database was created in spss version 11.0, a statistical processing application authored by norusis (1994), which was used to produce the final analyses. the variables of interest were cross-tabulated in spss to provide the tables for this article. chi-square tests were conducted for each cross-tabulation by spss, as well as correlation statistics. generally, an alpha level of 0.05 was used to distinguish significant results, though trends that were discernable by direct observation of visual representations of data but fell slightly outside of the significant range are noted on occasion. due to the small sample size provided by some of the groups, it is possible that some trends would be found to be significant if larger samples were available. results the tables included here give the results of the statistical cross-tabulation of the factors discussed above in tori frequency. all p-values given in the text are the result of pearson’s chi-square test unless otherwise noted. as with all archeologically derived data sets, it is important to remember that the standard statistical procedures used to test significance and correlations of variables assume a random sample of a normally distributed population, which is very rarely the case with archeological material. therefore, where trends were observed in the distribution of the data but not deemed to be significant at the p < 0.05 level, they are b. hassett age group less than 352 35-54 years� 55 and over4 sample a u b t a u b t a u b t chumash 11 1 12 1� 1� 2� 2� lachish 6 6 4 4 3 3 hawara 18 1 19 15 3 18 10 1 2 13 cannington 34 11 45 12 1 6 19 19 1 7 27 abingdon 43 43 34 2 2 38 21 1 22 spitalfields 17 1 1 19 41 1 42 29 1 30 30 poundbury 7 1 8 24 1 3 28 25 4 5 34 egypt 8 1 9 9 9 3 1 1 5 total 144 1 16 161 152 4 15 171 133 8 16 157 table 4. occurrences of torus mandibularis by age group and by sample. 1trait expression codes: absent (a), unilateral (u), bilateral (b), and total (t). 2pearson chi square = 24.455; df 14; p value = 0.040; combining categories of presence x2 = 15.634; df = 7; p value = 0.029. �chi-square = 23.945; df 14; p value = 0.047; combining categories of presence x2 = 16.788; df = 7; p value = 0.019. 4chi-square = 25.636; df 14; p value = 0.029; combining categories of presence x2 = 19.805; df = 7; p value = 0.006. fig. 3. example of torus mandibularis in a living individual (courtesy s. gill, laguna hills, ca). � still described, but all results should be viewed with this caveat in mind. populations highly significant variability in frequency of occurrence of torus mandibularis was found among the samples in this study (p < 0.000). table 3 provides the frequencies by sample of mandibular tori, along with the results of chi-square tests for significance. variation in frequency of torus mandibularis among age groups defined by degree of sutural closing, as shown in table 4, was also found to be significant among samples. the variability in prevalences between the sexes in different samples is greater for males (p < 0.09) than females (p < 0.11) or those of unknown sex (p < 0.19), as shown in table 5. also found to be highly significant was the variability of mandibular torus expression (torus size) among groups (p < 0.000), as seen in table 6. sex the degree of expression of the torus (whether slight, moderate, or pronounced) did not vary significantly between sexes. as mentioned above, however, variability between the sexes is evident among samples, particularly in males. age variation among age groups for mandibular tori, as defined by sutural closing, was not significant unless, as with sex, “group” is added as a variable. however, torus mandibularis unknown2 females� males4 sample a u b t a u b t a u b t chumash 6 6 22 1 2� 19 19 lachish 1 1 8 8 4 4 hawara 5 5 14 3 17 24 1 3 28 cannington 3 3 6 27 2 8 37 35 12 47 abingdon 20 1 21 38 1 39 40 3 43 spitalfields 12 12 29 1 1 31 46 1 1 48 poundbury 7 2 9 26 3 3 32 23 2 4 29 egypt 4 4 6 1 2 9 10 10 total 58 1 5 64 170 8 18 196 201 4 23 228 table 5. occurrences of torus mandibularis by sex and sample 1trait expression codes: absent (a), unilateral (u), bilateral (b), and total (t). 2chi-square = 23.514; df = 14; p value = 0.052; combining categories of presence x2 = 16.826; df = 7; p value = 0.019. �chi-square = 23.435; df = 14; p value = 0.054; combining categories of presence x2 = 18.307; df = 7; p value = 0.011. 4chi-square = 27.631; df = 14; p value = 0.016; combining categories of presence x2 = 18.888; df = 7; p value = 0.009. torus mandibularis expression sample absent slight moderate pronounced total chumash 47 1 48 lachish 13 13 hawara 42 7 49 cannington 65 17 8 1 91 abingdon 98 5 103 spitalfields 96 3 1 100 poundbury 55 10 4 69 egypt 20 � 2� total 436 46 13 1 496 table 6. occurrence of torus mandibularis expression by sample1 1chi-square = 55.688; df 21; p value = 0.000; combining trait expressions, x2 = 54,280; df = 14; p value = 0.000. 8 if age were to be defined by dental attrition classes as opposed to sutural closing, very significant variation in torus mandibularis is observed. the results of such a comparison are given under the functional stress: attrition heading below. torus mandibularis expression was not seen to vary between age classes. functional stress: attrition torus mandibularis showed significant variation in frequency between classes of occlusal tooth wear in the lower first molar (p < 0.001), as shown in table 7. significant (p < 0.01) differences between degree of expression of the mandibular tori in the different attrition classes was observed and may be seen in table 8. functional stress: mandibular robusticity no significant variation was found between size categories of mandible and occurrence of torus mandibularis as measured by maximum mandibular breadth and defined in millimetre increments. nor was any significance seen in the variation in degree of torus expression between size categories. functional stress: activity at tmj there was no significant difference in levels of osteophyte activity or porosity at the temporomandibular joint and degree of torus mandibularis expression or the incidence of mandibular tori. trait interaction no significance was attached to the co-occurrence of mandibular and maxillary tori or to the degree of expression of either tori with co-occurrence or the degree of expression of the co-occurring tori. discussion “group” appears to be a significant variable in prevalence of torus mandibularis and torus maxillaris. the results of this study are not surprising in confirming what is already an observed trend in the literature on the subject; that tori incidence rates vary widely according to group. the trait is seen here to occur in different frequencies and to different degrees in geographically and chronologically separated groups. no previous investigations of tori incidence have contested this variability, yet there remains a multitude of hypotheses as to why this variation occurs. it is useful to look to the reasons why multiple studies have reached such divergent conclusions in the light of the results of the present study. perhaps the largest factor in the disparity of conclusions arises from the different variables assessed among investigations. the variables tested in other works may have been chosen based on assumptions on the investigators part as to what factors could be involved in tori development. thus, in those studies that began with an assumption of genetic inheritance acting as the sole factor (suzuki and sakai, 1960; gould, 1964), b. hassett torus grade of lm1 attrition1 mandibularis 1 2 3 4 5 6 7 8 9 total absent 1 14 51 67 43 31 17 29 149 402 unilateral 1 2 2 1 2 � 11 bilateral 1 2 16 4 5 9 4 4 45 total 1 16 55 83 49 37 26 35 156 458 1chi-square = 55.688; df = 21; p value < 0.000; combining grades of presence x2 = 27.430; df = 8; p value = 0.001. table 7. occurrence of torus manibularis by grade of occlusal attrition on lm11 torus grade of lm1 attrition1 mandibularis 1 2 3 4 5 6 7 8 9 total absent 1 14 51 67 42 31 17 29 148 400 slight 2 2 11 5 5 7 4 6 42 moderate 2 5 1 1 2 1 1 13 pronounced 1 1 total 1 16 55 83 48 37 26 35 155 456 table 8. grade of torus manibularis tabulated against grade of occlusal attrition on lm11 1chi-square = 42.059; df = 24; p value = 0.013. 9torus mandibularis it is unsurprising that family relationships were the only variables considered. unfortunately, family relationships are very difficult to ascertain in archeological samples, and these could not be considered here. however, the disparity of modes of inheritance posited by familial studies and the concurrence of environmental factors with the frequency of tori suggest that a simple mendelian-mode of inheritance is not adequate to explain the variation in tori incidence among samples. other factors seem to play a role in determining the prevalence of these traits. as significant differences were found between the sexes in only some of the samples, the conclusions of previous researchers of an actual difference in prevalence rates between males and females, regardless of group, appear unsupported. however, as sexual dimorphism is known to differ in degree among groups (brothwell, 1981), it is possible that the variation observed here is a product of this difference, acting to influence robusticity of the masticatory complex. additionally, culturally defined sexual roles may include different functional stresses for men and women, further skewing any evidence of an actual tendency in tori prevalence should functional stress be a factor in development of the trait. it is worth noting here that haugen (1990) observed greater frequency of mandibular tori in eskimo men, though the ethnographic accounts of pederson (1944) make it clear that eskimo women had greater functional stresses placed on their jaws. as with variability between sexes, the variability among age groups in development of the tori of the jaws is less obvious from the results of this study than that among groups. “age” as a variable becomes especially problematic when it is assessed on skeletal material for a number of reasons. because archeological samples do not generally provide individuals of known ages, the categorization of individuals into age groups must be done on the basis of morphological changes in the skeleton that are normally associated with ageing. these techniques are only accurate to the degree that other factors influencing the morphology of the skeleton can be controlled for. walker (1978) points out that attrition rates depend not only on the age of an individual but also on the abrasiveness of the diet. the possibility that tori develop in response to the changing functional pressures on the jaw and teeth, along with this caveat, is why dental wear is not used here as an indication of age. this leaves the closing of cranial and palatine sutures as a basis for ageing the material studied here. an additional issue in using age as a variable arises, however, with the realization that the morphological changes to the cranium associated with age may be part of other skeletal processes affecting an individual’s pattern of sutural closing (e.g., trauma, etc.). an overall tendency towards early or late ossification due to genetic or nutritional factors, or several other conditions (e.g., general tendency to robusticity, etc.) that affect the skeleton may act to conflate or deflate evidence of a relationship between chronological age and the development of tori. in the first case, all care was taken to remove individuals with obvious disruptions to the normal pattern of sutural closing. the possibilities associated with the second case are discussed further below, while the remaining multitude of possible factors acting to influence skeletal morphology must remain as a caveat in assessing the import of age in development of torus mandibularis and torus maxillaris. the results of this investigation do show a significant variation between the age groups in development of mandibular and maxillary tori when “group” is added as a variable. this possibly reflects population-level differences in the morphological characteristics on which age was assigned, but other investigations have suggested that age is indeed a factor in tori development. mandibular torus is very rare in juveniles, excepting those samples that normally have a high frequency of the trait (haugen, 1990). development of tori is generally agreed to begin within the first 30 years of life, though may occasionally occur later (seah, 1995). the contention that tori development is not a slow, progressive process but rather a dynamic one (seah, 1995, contra haugen 1990) is perhaps supported by the evidence of this study, as degree of expression was not found to vary significantly among age classes. this has not been a universal finding; halffman et al. (1992) and eggen and natvig (1986) found that tori were more frequent in the middle-aged, and eggen (1989) also found no significant increase in frequency after ca. 30 years of age. johnson (1959), however, mentions that tori resorption, or shrinkage, has been observed in both the very old and those whose teeth have been removed. the results of this study show that the most significant variation in age groups between populations occurs within the 55+ age group (p < 0.03). these results suggest that is not so much a causal factor in development of the tori, but rather a covariant which is affected by the same factors acting to effect torus development. the first and foremost of the variables associated with age is the degree of occlusal wear of the dentition. tooth torus mandibularis dentate edentulous total absent 366 69 435 unilateral 1� 1� bilateral 45 2 47 total 424 71 495 table 9. grade of torus mandibularis partitioned by whether the cases was dentate or edenulous1 1chi-square = 6.887; df = 2; p value = 0.032. 10 wear is strongly correlated with age, and commonly used in archeological samples to categorize age. in this study, tooth wear was significantly correlated with the age assignments (r = 0.233, at a significance of p < 0.000). generally, attrition increases with age (walker, 1978; brothwell, 1981; waldron, 2001). but age is not the only factor acting to wear the dentition (walker et al., 1991). coarseness of diet or differing levels of functional stress on the teeth may hasten the normal process, with the result that individuals with different diets or stresses may show markedly different wear rates. wear rates may be expected, then, to vary among groups (walker, 1978). one of the most widely observed examples of this difference is found in the eskimos of north america, iceland, and greenland, who have very high attrition rates as well as a high frequencies of chipping and pitting of the teeth that coincide with the high functional demands they place on them. in the samples observed here, there is a definite variability among rates of attrition, as evidenced by the molars. the frequency of torus mandibularis is significantly correlated with the level of attrition recorded at the first molar (p = 0.000). the distribution of the tori over the wear classes clearly shows a gradual increase up to a peak in the number of occurrences around the fourth stage of wear, with the subsequent pattern of decline in frequency only occasionally interrupted. this is very suggestive when the reasons posited for development of the tori are considered. if the tori arise as a response to functional stress, evidenced by tooth wear, expectation is that the frequency of torus mandibularis would be low in individuals with low levels of wear. frequency would be expected to increase as functional forces acting to wear the teeth increase. should the tori develop as a skeletal response to mechanical forces, frequency would be expected to be highest in individuals with the most severe wear, with those exerting the most stress presumably exhibiting the most wear. however, frequency does not dramatically increase after the fourth stage of wear. a partial explanation for the lesser number of tori in the latter stages may be that, as tooth wear increases, the functionality of the teeth may be impaired, and the need for functional strengthening of the jaw may decrease if the jaw is no longer used due to tooth loss. the resorption of bone from the mandible in edentulous individuals due to this loss of function may partially explain the reduction of occurrence with the most severe wear. in examining torus mandibularis occurrences in dentulous and edentulous individuals, as defined by the premortem loss of the first and second molars, significant variability is found, which lends strength to this suggestion (fig. 4). this study did not find that osteophyte activity at the temporomandibular joint was significantly varied between those individuals with torus mandibularis. nor was there a significant difference in levels of porosity. this does not necessarily rule out the possibility of an association between disorders of the joint and the development of torus mandibularis; temporomandibular disorder (tmd) is only generally identifiable in the most severe cases from skeletal remains (s. hillson, pers. comm.). in clinical studies, torus mandibularis has been seen to correspond very significantly (p < 0.0005) to tmd as well as to one of the most common causal factors for tmd, namely parafunctional activity such as bruxism (kerdpon and sirirungrojying, 1999). radiographic measures of bone density at multiple locations in the body taken in a study of torus mandibularis suggest that higher bone mass density is significantly associated with development of the trait (hjertstedt et al., 2001), but, again, this was something the present study was unable to assess. general robusticity of the jaw has been thought to have some relation to development of torus mandibularis. eggen and natvig (1986) suggested that individuals with better developed jaws had higher frequencies of torus mandibularis. ossenberg (1981) hypothesized that the development of tori after puberty is possibly related to the greater food intake necessitated by growth, which in turn necessitates greater muscular power in order to process the larger amount of food. while many of the samples observed in the literature –with high prevalence rates of tori are generally robust in terms of skeletal build, the quality of robusticity is so ill-defined as to make analysis of this variable nearly impossible. with robusticity here defined by the thickness of the mandibular body, no significant b. hassett fig. 4. bar graph of the occurrence of torus mandibularis depending on whether the subject was dentate. 11 relationship between torus mandibularis and general robusticity was observed. this brings the discussion to the hypothesis of trait interaction. the concurrence of the two exostoses included in this study was insufficient to suggest a strong correlation. other researchers have debated the co-occurrence of torus palatinus, with some finding a correlation between the traits and some not. the investigations using the largest sample sizes have not seen a strong correlation, and the investigations into the effects of bone mineral density (hjertstedt et al. 2001) and parafunctional activities (eggen, 1954; eggen and natvig, 1986; kerdpon and sirirungrojying, 1999) have shown different prevalence rates for torus palatinus. in this study, the co-occurrence of torus mandibularis and torus maxillaris was not found to be significant in either degree or expression of frequency of incidence. this finding, taken in conjunction with results showing no correlation between possible causal factors in torus mandibularis development and torus maxillaris development, suggests that the two traits are not the result of a single causal factor, either environmental or genetic. the lack of co-occurrence in familial studies of the traits and in studies of environmental or functional stress lead to the conclusion that the tori arise due to separate stimuli. that is not to say absolutely that the same factors aren’t responsible for development of both maxillary and mandibular tori, but the inconclusive efforts to relate the maxillary tori to those factors, which show a significant relation to mandibular tori, suggest that the developmental process of the former is not identical to the latter. due perhaps to the rarity of torus maxillaris, less can be said about the possible correlations of environmental or functional stress. this finding follows logically in steps of the growing consensus that the other major tori of the jaw, torus palatinus and torus mandibularis, are affected by different factors (kolas et al., 1983; haugen, 1990; seah, 1995). in relation to the hypotheses surrounding torus etiology outlined previously, this study has found the following: • frequency of both mandibular and maxillary tori varies between populations to a significant degree, suggesting that genetic inheritance could play a role in torus etiology. • sexual dimorphism in tori frequency is found to be significant within some populations, but not significantly varied in others, possibly as a result of the different effects of culturally defined labour roles on the sexes. additionally, this may explain the disparate results of previous work in establishing whether the traits are more prevalent in males, females, or neither. • age is not found to be a significant factor in torus development when measured on criteria other than dental attrition, suggesting a more dynamic, possibly environmentally induced, pattern of growth. while robusticity of the mandible was not strongly correlated with age or tori frequency, age was strongly correlated with attrition classes. the interaction of age with tooth wear is well established, which may explain why previous research has suggested age as a factor in torus development. • masticatory hyperfunction, evidenced by tooth wear, is seen to be correlated with mandibular torus prevalence. however, frequency of the trait is greatest at a lower level of wear and there is a pronounced difference in trait distribution between dentulous and edentulous individuals. this may suggest that mandibular tori are a successful response to functional stress, as opposed to the result of loss of masticatory function with increasing dental attrition conclusions the results of this study conform to a pattern suggested by the most recent research into tori etiology. in the last 15 years, the general consensus has been that mandibular tori at least arise from a combination of genetic and environmental factors. a more consistent observation of any correlations, might have been observed, should they exist, if all investigations included the multiplicity of variables proposed as affecting the occurrence of mandibular torus. however, because research designs have often been constructed in a dichotomizing either/or fashion to show the significance of one particular variable in the development of tori at the expense of any other factors, there has been a tendency to include only those factors the investigator wishes to demonstrate as being either positively or negatively correlated with tori incidence. this is unfortunate, because the widely divergent results produced by such studies only serve to cloud the issue further. by incorporating as many variables as possible into an investigation of tori development, the polarised results of earlier studies become understandable as partial glimpses of a multifactorial etiology only discernable when a wide ranging investigation is carried out. the results obtained here suggest that functional stress plays a large role in the development of mandibular tori. the correlation of age to torus development remains unclear, though it is vital to remember that tooth wear is strongly correlated with age. had the age assessments used here relied on attrition categories to define age, as is common with archeological samples, the variation between age categories and attrition categories would be identical. a possible result of this correlation is the overemphasis of the importance of age in tori development, as the passage of time allows increasing amounts of wear and stress to act on the jaw. significant variation in tori development between classes of tooth wear were found that support the idea of the torus arising as a response to functional stress acting on the mandible in the form torus mandibularis 12 of increased functional demand on the masticatory complex. however, histological studies have not borne out the expectation that the bony structure of the tori themselves would reflect the direction of this mechanical force. this leads to the conclusion that the exostoses of the mandible are not purely a skeletal response to pressure, an argument that also finds support in this study’s finding a lack of significant correlation between overall mandibular robusticity and trait incidence. further refuting the idea of a single variable, functional stress, as the sole causal factor in tori development, are the familial studies carried out in living populations of known biological relations. variation among populations of different origins in torus frequency must be accounted for, and the most appropriate explanation may be found in the concept of the threshold trait as proposed by wright (1963). if the inherited factor of torus mandibularis is a liability for development, an individual tendency towards formation of either this particular exostosis or exostoses in general, then etiology must be multi-factorial, with environmental factors acting to determine whether or not the threshold for development is surpassed. this model explains both the variability in frequency among groups and among dental attrition classes found in this study. it is hoped that future research into the development of mandibular tori will address the issues raised by this study. paramount of these issues is the establishment of a standardised method of recording the presence of the tori, which may only be accomplished by assigning metric categories to what have been somewhat arbitrary size distinctions. additionally, the correlation between relatively good periodontal conditions and torus development should be investigated in a broader, crosspopulation context. a final direction of considerable interest is towards a better understanding of trait interaction, particularly between all exostoses of the face and skeleton, such as palatine and maxillary tori. in conclusion, it seems necessary to reconsider the suitability of torus mandibularis for analysis of biological distance between populations. unless environmental factors can be completely controlled for, population frequencies may differ or converge without relation to the degree of genetic relation between groups. this study has shown the significance of dental attrition in variance of torus mandibularis frequency, suggesting that environmental factors should be carefully weighed when assessing the genetic component of tori etiology. while the entire battery of non-metric traits is beyond the scope of this study, the findings related here suggest that careful consideration of trait etiology is a necessary step in choosing variables for biodistance analyses. not all non-metric traits can be considered a priori products of genetic variation, as the investigation of the etiology of torus mandibularis shows. acknowledgements the author gratefully acknowledges all of the assistance generously given by dr. simon hillson and dr. daniel antoine and dr. robert kruzynski of the department of anthropology at the natural history museum of london. additional thanks are in order to dr. louise humphreys and to the entire staff of the department of anthropology at the natural 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editors. advances in dental anthropology. new york: wiley-liss, p 169-178. wright s. 1968. evolution and the genetics of populations: genetic and biometric foundations. vol. 1. chicago: university of chicago press. markowitz 1996.3 pg11.jpg pg12.jpg pg13.jpg pg14.jpg pg15.jpg pg16.jpg pg17.jpg oglivie 1996.5 pg19.jpg haeussler 1997.6 pg21.jpg loth 1987.1 pg2.jpg turner 1998.2 pg10.jpg pg11.jpg pg12.jpg nelson 1997.2 pg10.jpg pg11.jpg pg12.jpg pg13.jpg pg14.jpg mcnamara et al. 1998.4 pg12.jpg pg13.jpg pg14.jpg cucina 1996.8 pg23.jpg ichim et al. 2005.3 50 the canine tuberculum dentale is a cingular derivative found on the lingual surface of the maxillary anterior teeth (scott and turner, 2000). it varies in expression from a low ridge to a well-formed cusplet (hillson, 1986). while a number of studies have reported on its incidence and expression in modern and archaic populations (e.g., scott and dahlberg, 1982; cucina et al., 1999; bailey, 2000), to the best of our knowledge none has focused on its biomechanical significance. in this paper, we use three-dimensional finite element analyses on two canines, one with and one without a tuberculum dentale, morphed from a scanned image of a human upper canine, to investigate whether this trait plays a significant role in the structural response of the tooth under functional loading. materials and methods source model and morphing we scanned a human permanent upper canine, extracted for periodontal reasons, on a micro-ct scanner (skyscan 1072 system). the sections were taken at 15micron intervals, yielding a stack of 1954 slices. using in-house software, an initial assembly of two meshes of the surfaces and interfaces of the canine was generated. the result was an initial surface mesh that enclosed the volumes of enamel and dentine. the root cementum layer was not modeled because of its particularly small dimensions and the limited relevance for our study. we then morphed two crown shapes, one with a stylized tuberculum dentale and the other with a flattened palatal surface. morphing was carried by simultaneously displacing the vertices of the outer and inner surfaces of the enamel volume and keeping the enamel thickness in the morphed models similar to that *correspondence address: jules kieser, department of oral sciences, faculty of dentistry, university of otago, dunedin, new zealand e-mail: jules.kieser@stonebow.otago.ac.nz abstract we evaluate the structural significance of the development of a canine tuberculum dentale by means of three-dimensional finite element analysis. using a scanned human permanent canine, we construct a computer generated canine, together with alveolar bone and periodontal ligament onto which we morph two cingulum shapes, namely a flat palatal surface and a stylised tuberculum dentale. we then subject the three shapes (flat, normal cingulum, and pronounced tuberculum dentale) to a normal occlusal force and we record principal and von mises stresses in the crowns. our results show that stresses are concentrated at the cingulum and in the approximal areas, and that these do not differ between the three forms. we conclude that the development of a tuberculum dentale does not confer biomechanical advantage to the human canine. dental anthropology 2005;18(2):50-54. of the original scanned tooth. hence, three geometrical tooth crowns were generated this way: a source model constructed from the micro-ct data, a model with a stylized tuberculum dentale and model with a flat palatal shape. finite element models after applying the surface meshing we performed a nurbs conversion (non-uniform rational b-splines) that defined the respective solid volumes for each of the three models. this was done by patching, using a feature available with a general purpose cad software (smurf for rhinoceros 3d for windows, robert mcneel and associates, usa). patching consisted of applying quadrilateral nurbs onto the surface of the mesh, hence covering the original mesh with tiles of rational surfaces with tangent continuity that are later joined into closed solids. two matching bodies were thus been created, one representing the enamel and the other the dentine, in contact along the entire dentinoenamel junction. for reasons of computational-efficiency, the anatomic roughness of this junction, well captured on the ct reconstruction was neglected and a smoother junction created. the pulp space was modeled as a void inside the dentine volume, because its young’s modulus is negligibly small compared with that of the surrounding enamel and dentine (hojjatie and anusavice, 1990). biomechanical analysis of the canine tuberculum dentale ionut ichim, michael swain and jules kieser* department of oral sciences, faculty of dentistry, university of otago, dunedin, new zealand 51 we then simulated the periodontal ligament creating a uniform 0.3 mm shell around the root, and also a bone supporting volume to receive the socket thus created. the upper limit of the bone was set 2 mm below the cervical line of the tooth, thus simulating the actual anatomic situation (schroeder, 1991). a 2.3 mm2 loading area was defined on the crown, circumscribing a hypothetical palatal wear facet where the lower canine occluded. the high-fidelity shape generated from micro-ct allowed an easy recognition of the wear facets and a realistic placement of functional loading was achieved. the loading area was positioned identically in all three models. the resulting geometric assemblies were imported into general-purpose fea software (cosmos designstar, structural research and analysis corp., usa) and meshed using parabolic tetrahedral solid elements. this yielded 62,925 elements for the flat cingulum model, 62,964 elements for the unaltered shape and 63,010 elements for the prominent cingulum model. the models were rigidly restrained along the lateral and basal surfaces of the bone with the tooth free to move within the defined periodontal space. we assigned isotropic homogenous materials properties for the enamel, dentine and cancellous bone as described in the literature (table 1). it is known that the tooth structures are made of non-homogenous and anisotropic materials yet the regional property variation is restricted to a microscopic scale and comparisons with real physical specimens have shown that the material behavior is elastic during functions (kinney et al., 1999; qin and swain, 2004). the periodontal ligament was assumed to be a linear elastic material with an elastic modulus of 12 mpa and poisson’s ratio of 0.45. we obtained these values in a preliminary analysis by steadily increasing the elastic modulus of the material until the unaltered canine intruded 0.3 mm under an axial load of 300 n. this mobility was employed to fit previous in vivo mobility data reported in the literature (muhlemann, 1967). because this showed that during incision the canine cingulum area was stress-free, we discarded this loading case. therefore only the palatal contact was prescribed as the loading condition, simulating the occlusion, with the force acting on the previously defined areas. because no data were available for the contact angle between the upper and lower canines, we approximated this to be 160º based on the angle of the incisors (milot and stein, 1992). the biting force was estimated at 200 n (derived from miyaura et al., 1999) for all three cases. we then assessed the principal stresses (σ 1 and σ 3 ) and von mises stresses for each loading case. results for a given loading case, the stress analysis results show that the modest tuberculum dentale shape has little influence if any, upon the structural loading of the canine crown. first principal stress plots reveal two areas of high tension in all three models which are located tuberculum dentale elastic poisson’s tissue modulus ratio enamel 130 gpa 0.3 dentine 14.7 gpa 0.3 periodontal ligament 12.0 mpa 0.45 alveolar bone 490 mpa 0.3 table 1. material properties used in the present fea analysis (o’brien, 2002) fig. 1. first principal stress in (a) flat palatal surface, (b) normal, and (c) stylized tuberculum dentale models. note the constant distribution of tensile stresses on the proximal surfaces of the crown, adjacent to the cementoenamel junction. 52 on the proximal surfaces, close to the cementoenamel junction. the values of this proximal tensile stress are close to the reported ultimate tensile strength of the enamel (fig. 1). an axial section shows that tensile stresses follow a similar path in all three canine shapes, with a high of 38-43 mpa located under the loading area, on the dentinoenamel junction. tensile loading on the cingulum area increased from 17 mpa in the flat shape to 14 mpa in the normal cingulum and 11mpa in the tuberculum dentale shape (fig. 2). the third principal stress analysis reveals that the compressive stress is located on the buccal half of cervical margin and also at the loading point. the numerical values were similar for all three cases ranging from 47 to 50 mpa (fig. 3). von mises stresses show a similar pattern in all three models, with two main concentration areas, one along the cervical margin and the other on the loading sites. however, a small decrease in von mises stresses is recorded parallel with the increase in size of the tuberculum dentale (fig. 4). i. ichim et al. fig. 2. axial section plots in (a) flat palatal surface, (b) normal, and (c) stylized tuberculum dentale models. fig. 3. axial section plots of the third principal stress in (a) flat palatal surface, (b) normal, and (c) stylized tuberculum dentale models. the distribution of the compressive loading on the buccal half of the cej is evident. 53tuberculum dentale fig.5. the “resistance frame” inside the crown showing the volume that will experience tensile stresses over 10 mpa. note the hoop-like shape and the maximal tensions on the proximal surfaces. fig. 4. von mises stresses in the (a) flat cingulum, (b) normal, and (c) prominent cingulum models. 54 discussion recently, bailey (2000) presented data on a number of dental non-metrical traits to ascertain relationships among early and recent human populations. one of her interesting findings is that neandertals showed an average frequency of 87.5% for the tuberculum dentale, which contrasts sharply with trait frequencies in british (25.5%) and north african (38.8%) populations. this is not surprising, given the numerous craniodental and postcranial differences in robusticity reported between neanderthals and modern humans (e.g., rak, 1986; stringer and gamble, 1993; holliday, 1997). the question now arises, does the tuberculum dentale confer additional robusticity to the typical neanderthal canine? in this paper we test the hypothesis that the tuberculum dentale plays a significant role in the structural response of the canine tooth under functional loading. to this end, we compare the numerically determined values of three different shapes of the canine cingulum area under identical loading conditions. for each crown form, we analyze the loading case, the principal stresses, σ 1 , σ 3 and von mises stresses. we show that compressive stresses are located mainly on the buccal side, along the cementoenamel junction, with determined values well within the biological material safety limits of enamel (figs. 1, 2). tensile and von mises stresses are dominant on the cervical third of the lingual aspects of the crown in each of the three morphological shapes (figs 3, 4), again with minimal differences between cingulum forms. this strongly suggests that the tuberculum dentale does not in fact strengthen the canine under occlusal loads. the tensile stress analysis allows for a “resistance frame” to be defined inside the crown which shows the part of the structure that is experiencing the greatest tension (fig. 5). in structural terms, this frame will provide stiffness to the crown. the frame thus generated encircles two-thirds of the cervical contour on the lingual aspect of the tooth and extends towards incisal surface, along the marginal ridges of the crown. neither the locations nor the intensity of the peak tensile stresses are affected by differences in the development of the canine cingulum. again, this supports the suggestion that the tuberculum dentale does not play a significant role in the structural response of the canine tooth under functional loading. literature cited bailey se. 2000. dental morphological affinities among late pleistocene and recent humans. dent anthropology 14:1-8. cucina a, lucci m, vargiu r, coppa a. 1999. dental evidence of biological affinity and environmental conditions in prehistoric trentino samples from the neolithic to the early bronze age. int j osteoarchaeol 9:404-416. hojjatie b, anusavice kj. 1990. three-dimensional finite element analysis of glass-ceramic dental crowns. j biomech 23:1157-1166. hillson s. 1986. teeth. cambridge: cambridge university press. kinney jh, balooch m, marshall gw, marshall sj. 1999. a micromechanics model of the elastic properties of human dentine. arch oral biol 44:813-822. milot, p. stein rs. 1992. root fracture in endodontically treated teeth related to post selection and crown design. j pros dent 68:428-435. miyaura, k, matsuka y, morita m, yamashita a, watanabe t. 1999. comparison of biting forces in different age and sex groups: a study of biting efficiency with mobile and non-mobile teeth. j oral rehab 26:223-227. muhlemann, hr. 1967. tooth mobility: a review of clinical aspects and research findings. j periodontol 38: suppl: 686-713. o’brien, wj. 1997. dental materials and their selection. chicago: quintessence publishing. qin q, swain m. 2004. a micro-mechanics model of dentin mechanical properties. biomaterials 25:50815090. schroeder he. 1991. oral structural biology. zurich: thieme. scott rc, dahlberg aa. 1982. microdifferentiation in tooth crown morphology among indians of the american southwest. in: kurtén b, editor. teeth: form, function and evolution. new york: columbia university press, p 259-291. scott gr, turner cg. 2000. the anthropology of modern human teeth. cambridge: cambridge university press. i. ichim et al. sobhi et al. 2007.2 33 the human dentition is a good model system for examining the nature and extent of asymmetries in morphology and development because teeth are arranged in the dental arches as antimeric pairs within different tooth classes, i.e., incisors, canines, premolars and molars. dental asymmetry has been studied in relation to asymmetry type (fluctuating versus directional), dentition (primary or secondary), causes (genetic and environmental) and associated factors (sex, ethnicity and tooth or arch type). previous studies of asymmetry in the human dentition have considered dental crown size, crown morphology and dental development, including tooth emergence and eruption (garn and bailey, 1977; corruccini and potter, 1981; boklage, 1987; kieser, 1990; harris and bodford, 2007). asymmetry is said to be directional when one side regularly displays greater and/or earlier development than the other. directional asymmetry (da) has been reported in the primary dentition (townsend et al., 1999) while studies of the secondary dentition have shown both the presence (lauterstein et al., 1967; staley and green, 1971; harris, 1992) and absence (townsend, 1985) of da. significant links between da and emergence/ eruption timing have been described (garn and smith, 1980; heikkinen et al., 1998) while more recent investigations have considered the relationship between da and broader functional lateralities such as eyedness and handedness (heikkinen et al., 2001). random, nondirectional differences termed fluctuating asymmetry (fa) are thought to indicate an inability of the individual to buffer against developmental disturbances (van valen, asymmetrical eruption of permanent teeth in australian aborigines p. sobhi, s. mihailidis*, j. r. rogers, t. e. hughes, g. c. townsend craniofacial biology research group, school of dentistry, the university of adelaide. australia abstract: a better understanding of the factors influencing tooth eruption is important given the association between altered eruption patterns and crowded or decayed teeth. hence, the aims of this study were to quantify the extent of asymmetry in tooth eruption and to determine whether eruption asymmetry was significantly influenced by sex, tooth position or timing of emergence. additionally, directionality of asymmetry and variation between ethnic groups were also explored. data collection was based on the examination of serial dental casts from a sample of 90 aborigines (50 male, 40 female) aged 6 to 18 years from the yuendumu settlement in the northern territory of australia. these casts were obtained at yearly intervals from the 1950s to the early 1970s. tooth antimeres on each cast were compared using a 4-grade eruption score. relatively high (> 70%) inter and intra-observer concordances confirmed reliability of the recording system. asymmetry frequencies were calculated and associations between variables assessed using chi-square analyses, with statistical significance set at alpha = 0.05. evidence of patterned asymmetry for permanent tooth eruption was noted among the sample of australian aborigines, with the distally positioned, laterforming teeth showing the highest levels of asymmetry. dental anthropology 2007;20:33-41. 1962). hence, fa is considered to reflect the magnitude of developmental disturbances or, as waddington (1957) termed, developmental noise. the effects of developmental noise or environmental stresses on dental asymmetry have been established using animal experiments with stressors such as noise, cold and heat (bader, 1965; siegel and smookler, 1973; siegel and doyle, 1975; siegel et al., 1977). human studies, however, have measured the effects of stress using ethnicity, age and degree of modernization as proxies for stress. studies have mostly cited greater asymmetry among indigenous (kieser and groenevald, 1988; townsend, 1981), less contemporary (black, 1980b) and older (kieser et al., 1986) populations. kieser and groenevald (1988) proposed that it was not only the ‘nature and severity of stress’ but the ‘ability of the individual to buffer against stress,’ which may be useful in explaining results where either nil, or surprisingly significant associations between ethnicity and asymmetry (de melo et al., 1975; black, 1980b; kieser et al., 1986; kieser and groenevald, 1988) have been found. local factors such as caries-infected primary teeth (adler, 1963; lauterstein et al., 1967), space constraints (sofaer et al., 1971) and more general factors such as duration of odontogenesis (townsend and brown, 1980) have been used to explain why asymmetry is greater in the secondary dentition compared to the primary *correspondence to: suzanna mihailidis, school of dentistry, university of adelaide, australia 5005 e-mail: suzanna.mihailidis@adelaide.edu.au 34 dentition (garn and bailey, 1977). it is thought the more time spent in the pre-calcification stage may be linked to greater asymmetry between teeth (mizoguchi, 1983, 1986) due to increased opportunity for environmental disturbances to deviate developing teeth away from their genetically determined paths. while early studies by garn et al. (1965) proposed the female double-x chromosome provided greater buffering capacity and hence resulted in less asymmetry in females compared to males, more recent studies have not found significant variation by sex for either primary (townsend, 1981; townsend et al., 1999) or secondary (lauterstein et al., 1967; staley and green, 1971) teeth. while some researchers have found no significant differences in dental asymmetry (cusp occurrence) between monozygotic, dizygotic and non-twins (staley and green, 1971), others have claimed that there are differences in dental asymmetry not only between different types of twins but also between twins and singletons (boklage, 1987). examples of geneticallylinked dental asymmetries, for example in down syndrome, have also been reported (garn et al., 1970; townsend, 1983). studies reporting on arch-related asymmetry (townsend, 1981; kieser and groenevald, 1988) have shown inconsistent findings while toothrelated asymmetry seems to strongly support the concept of morphogenetic fields proposed by butler (1939) and subsequently modified by dahlberg (1945). this pattern of asymmetry is well cited in the literature (garn and bailey, 1977; townsend, 1981) with few exceptions (kieser and groenevald, 1988). in regards to tooth form, numerous studies can be found concerning antimeric variation in tooth size and shape (garn and bailey, 1977; black 1980a,b; harris and nweeia, 1980; townsend, 1981, 1985; kieser et al., 1986; kieser and groenevald, 1988; townsend et al., 1999; khalaf et al., 2005) but relatively fewer investigations that have considered asymmetry in the timing of tooth eruption among human populations (tomes, 1859; lysell et al., 1962; lauterstein et al., 1967; staley and green, 1971; de melo et al., 1975; nystrom, 1977; garn and smith, 1980; heikkinen et al., 1998, 2001). tomes (1859) suggested that teeth on the left side erupt earlier than those on the right while lysell et al. (1962) also reported similar findings in their study of primary tooth emergence in swedish children. still, there are studies that have failed to detect any significant differences in timing of emergence between antimeric pairs (staley and green, 1971; de melo et al., 1975; nystrom, 1977). more recent studies by heikkinen et al. (1998) have established significant associations of sex and ethnicity on timing of tooth eruption by comparing samples of finnish and us children. an exciting recent development has been the link made between eruption asymmetries and functional lateralities by examining tooth eruption sequence as an indicator in the timing of overall laterality (heikkinen et al., 2001). while information regarding the existence of systematic relationships or patterned asymmetry is growing, there are still many aspects of odontogenic mechanisms—one of which includes dental eruption asymmetry—that are yet to be fully understood. hence the aims of this study were to describe the nature and extent of asymmetry in permanent tooth eruption among a sample of australian aborigines. several specific hypotheses were considered in relation to tooth eruption: 1. more distally placed teeth within each tooth class will display greater asymmetry than more mesially placed teeth (butler ’s field theory) 2. females will exhibit greater symmetry than males (better buffering with two x chromosomes) 3. later-erupting teeth will have higher levels of asymmetry compared to earlier-erupting teeth (longer time spent in development increases exposure to environmental disturbances) 4. directional asymmetry in tooth eruption will exist for some teeth (some evidence from previous studies) 5. variation in tooth eruption symmetry will exist between australian aborigines and other ethnic groups (previous findings in other ethnic groups) study population and methods this study was based on the examination of serial dental casts obtained at approximately yearly intervals of 90 australian aborigines, 50 males and 40 females, stored in the murray barrett laboratory of the adelaide dental hospital. the casts had been prepared during visits of anthropological research teams from the university of adelaide to the yuendumu settlement from the 1950s until the early 1970s. yuendumu settlement, situated approximately 300 km northwest of alice springs in the northern territory of australia, was created in 1946 and comprised a relatively selfcontained aboriginal population. the people belonged predominantly to the wailbri and pintubi tribes and were of pure aboriginal ancestry as far as could be ascertained. from a cultural point of view, the group was still in a transition stage—from a food gathering/ hunting society to a reliance on western civilization for its basic needs. the geographically isolated conditions at yuendumu provided a rare opportunity to study a group of people who had not yet been influenced to any great extent by the effects of european culture. damaged casts and those displaying missing teeth were excluded from the sample. every effort was made to include individuals with the maximum number of available serial dental casts during the period of eruption of the permanent teeth. the ages of the subjects were between 6 and 18 years. the method of scoring tooth eruption followed that of heikkinen et al. (1999) where tooth antimeres on each cast were compared p. sobhi et al. 35 using a 4-grade eruption score. each of the eight pairs of permanent teeth in both the maxilla and mandible were scored for eruption status. the eruption stages were defined as follows: 1. tooth not emerged 2. occlusal surface of the tooth recently emerged 3. tooth crown half erupted 4. eruption of tooth complete or nearly complete the term “emergence” is used to refer to the point at which a tooth appears in the oral cavity, and the term “eruption” refers to the process by which a tooth moves into occlusion with its opponent(s). the cast on which a tooth was first evident was used for scoring the stage of eruption of that particular tooth. teeth were given a score of 1 to 4 according to their eruption status. most of the tooth pairs that were included in the analysis were in the erupting phase; that is, they were scored as 2 or 3, but a small number of tooth pairs where one tooth was scored as a 1 and the antimere as a 4, were also included. tooth pairs were not included if they were both scored as 1 or 4. interand intra-observer reliability in scoring was determined from double determinations on 20 randomly selected casts. where discrepancies occurred, the casts were re-examined, and a decision was made as to the appropriate score. chi-square tests were used to test for significant variation in tooth eruption status between: • teeth within a tooth class, namely i1 versus i2, p1 versus p2, m1 versus m2; • australian aboriginal male and female children; and • australian aboriginal, american and finnish children (where data reported by heikkinen et al. (1999) were used for making comparisons). statistical analysis was conducted using spss software with significance set at the conventional level of alpha = 0.05. results table 1 presents the inter-observer and intraobserver percentage concordances for scoring eruption status based on double determinations. generally, the concordance percentages were higher in the mandible compared with those in the maxilla. for example, concordance for scoring eruption of the lower laterals table 1. interand intra-observer percentage concordances for eruption status1 inter-observer intra-observer tooth number (% concordance)2 (% concordance)2 11, 21 85 85 90 95 12, 22 85 75 70 85 13, 23 95 80 100 90 14, 24 95 95 100 100 15, 25 75 90 85 90 16, 26 85 80 95 95 17, 27 90 85 95 95 18, 28 85 90 95 95 31, 41 90 90 95 95 32, 42 100 100 100 100 33, 43 95 95 95 95 34, 44 75 75 80 90 35, 45 95 95 100 95 36, 46 85 85 90 90 37, 47 80 90 95 100 38, 48 80 90 85 100 1notes: a) sample size for comparisons = 20 subjects b) number of individual teeth = 17 to 20 c) the notation system used for tooth identification in tables 1-5 is the federation dentaire internationale (fdi) notation that is based on a two-digit system. the first digit identifies the quadrant (numbered 1-4 for permanent teeth, beginning at the patient’s upper right and proceeding in a clockwise direction) while the second digit identifies the tooth within the quadrant (numbered 1-8 and beginning from the midline) e.g., a maxillary right permanent central incisor is a 11 and a mandibular left permanent third molar is a 38. 2 the two numbers refer to percent concordance scored on each of the two teeth (homologous teeth on left and right quadrants). for example, there was 85% inter-observer concordance for the right (tooth 11) and left (tooth 21) maxillary central incisor, whereas intra-observer concordance was 90% and 95%, respectively for teeth 11 and 21. asymmetrical tooth eruption 36 table 2. symmetrical-asymmetrical eruption by tooth class teeth in symmetrical asymmetrical tooth active phase eruption eruption tooth class number n n % n % incisor 11, 21, 31, 41 98 78 80 20 20 12, 22, 32, 42 132 91 69 41 31 premolar 14, 24, 34, 44 109 45 41 64 59 15, 25, 35, 45 99 30 30 69 70 molar * 16, 26, 36, 46 74 49 66 25 34 17, 27, 37, 47 138 76 55 62 45 18, 28, 38, 48 98 40 41 58 59 *chi-square analysis (p < 0.05) table 3. symmetrical eruption by sex and emergence phase1 mean emergence mean emergence symmetrical symmetrical tooth males females eruption, males eruption, females number (years) (years) n % n % first emergence phase2 36, 46 6.4 5.1 8 44 5 83 16, 26 6.4 5.7 22 81 14 82 31, 41 6.6 6.4 15 71 11 79 11, 21 7.0 7.3 32 82 20 83 32, 42 7.2 7.3 29 76 18 72 12, 22 8.5 8.1 21 57 23 72 second emergence phase 33, 43 10.0 9.1 20 49 21 62 14, 24 10.3 9.8 13 41 15 48 34, 44 10.5 9.9 9 36 8 38 13, 23 10.5 10.1 24 59 13 38 37, 47 11.2 10.8 16 46 17 63 15, 25 11.4 11.0 8 30 9 38 35, 45 11.5 11.0 8 28 5 26 17, 27 11.5 11.0 25 61 18 51 18, 28 16.8 16.1 9 38 8 36 38, 48 16.5 16.1 11 37 12 55 1 no significant association between sex and symmetrical eruption (p > 0.05) but significant assocation between emergence phase and symmetrical eruption status (p < 0.05) based on chi-square analyses. 2first emergence phase refers to the time interval during which the tooth groups 36, 46 to 12, 22 emerge, between 5.1 and 8.5 years. second emergence phase refers to the time interval during which the tooth groups 33, 43 to 38, 48 emerge between 9.1 and 16.8 years of age. reference: mean emergence times (brown et al., 1979) was 100% for both sets of observations. generally, there was higher concordance for intra-observer comparisons than for inter-observer comparisons but, overall, the percentage concordances were relatively high indicating that the scoring system was reliable and that errors in scoring were unlikely to bias the results. table 2 presents the percentages of teeth showing symmetrical and asymmetrical eruption in the australian aboriginal sample with results categorized by tooth class. initial analyses did not uncover significant variation by sex and therefore data were combined to increase sample sizes. the results indicate significantly higher asymmetry for the more distal teeth in the molar tooth class supporting the theory of morphogenetic fields (dahlberg, 1945). for example, less than half (41%) of third molars exhibited symmetrical eruption p. sobhi et al. 37 compared to two thirds (66%) of first molars. results comparing the percentage of antimeric pairs showing symmetrical eruption against mean emergence times for australian aboriginal males and females (brown et al., 1979) are presented in table 3. while no significant association was found between symmetrical eruption frequencies and sex, there was a significant association between phase of emergence and symmetrical eruption, with later-erupting teeth (represented in the second emergence phase) displaying significantly higher levels of asymmetrical eruption than the earlier-erupting teeth (represented in the first phase of emergence). table 4 provides percentages of teeth showing directional eruption asymmetry in australian aborigines. initial analyses did not uncover significant variation by sex and therefore data were combined to table 4. distribution of directionality among asymmetrically erupting antimeres asymmetrical asymmetrical teeth in eruption eruption tooth active phase r > l l > r number n n % n % 11, 21 11 7 64 4 36 12, 22 25 16 64 9 36 13, 23 38 21 55 17 45 14, 24 35 17 49 18 51 15, 25 34 18 53 16 47 16, 26 8 4 50 4 50 17, 27 * 33 5 15 28 85 18, 28 29 11 38 18 62 31, 41 9 5 56 4 44 32, 42 * 16 12 75 4 25 33, 43 * 34 23 68 11 32 34, 44 * 29 20 69 9 31 35, 45 * 35 25 71 10 29 36, 46 * 17 2 12 15 88 37, 47 29 14 48 15 52 38, 48 29 15 52 14 48 *chi-square analysis (p < 0.05) table 5. symmetrical eruption by ethnic group us us australian tooth caucasian african american finnish aboriginal number n % n % n % n % 11, 21 * 123 51 117 58 262 86 52 83 12, 22 * 87 52 116 46 222 74 44 64 13, 23 * 10 53 45 42 202 66 37 49 14, 24 * 6 16 39 28 175 58 28 44 15, 25 * 2 7 4 5 158 54 17 33 16, 26 276 78 359 83 253 83 36 82 17, 27 11 61 123 72 205 68 43 57 31, 41 * 481 93 333 98 270 89 26 74 32, 42 * 145 53 154 63 234 77 47 75 33, 43 * 9 29 124 57 195 64 41 55 34, 44 * 17 45 32 24 183 60 17 37 35, 45 * 2 13 4 5 180 62 13 27 36, 46 * 142 66 133 72 256 84 13 43 37, 47 10 63 64 57 202 67 33 53 *chi-square analysis (p < 0.05) asymmetrical tooth eruption 38 increase sample sizes. significantly advanced rightsided eruption was found for the mandibular lateral incisors, canines and first and second premolars, while significantly advanced left-sided eruption was evident for the maxillary second molars and lower first molars. proportional estimates of symmetrically erupting antimeric tooth pairs from a cross-sectional sample of 2092 african american and caucasian american children and a longitudinal sample of 481 finnish children (heikkinen et al., 1999) are presented alongside estimates obtained for australian aborigines in the current study (table 5). chi-square tests comparing the extent of asymmetry between the four samples yielded statistically significant results, with all teeth except the maxillary first and second molars and mandibular second molars exhibiting significant variation by ethnic group. there were, however, limitations in comparing between these studies, including differences in sample sizes and sex distribution within the samples. although the same recording system was used, inter-observer comparisons could not be carried out to determine reliability. hence, significant findings should be considered with caution given the limitations in making comparisons between studies. overall trends included generally higher levels of eruption symmetry among the finnish and australian aboriginal samples compared to the us african american and caucasian samples. antimeric tooth pairs that were found to exhibit the greatest level of stability across ethnic groups included the early emerging lower central incisors and upper first molars. in almost all cases, the more distal teeth in each morphogenetic field tended to be more asymmetrical across all samples. there were, however, exceptions: upper lateral incisors (us caucasian sample), lower second premolars (finnish sample) and lower lateral incisors and second molars (australian aboriginal sample). discussion this study adds to the available information regarding patterns of asymmetry observed for permanent tooth eruption, which relates to: morphogenetic fields, increased buffering capacity of females, timing of emergence, and directional asymmetry. the influence of ethnicity, as an indicator of environmental stress influencing eruption symmetry, was less clear. there were obvious limitations when comparing samples from different studies related to differences in methodological approaches. despite these limitations, some apparent general trends were evident. the results pertaining to our first hypothesis (table 2) are in support of butler ’s field theory (butler, 1939; dahlberg, 1945), based on the concept that distal teeth within each morphogenetic class tend to be more variable than the more mesially positioned key tooth. this tends to occur with the exception of the lower lateral and central incisors, which exhibit the opposite pattern and are often considered to be an exception to the rule. these findings are also well in accordance with the general literature (garn and bailey, 1977; townsend, 1981; kieser et al., 1986; khalaf et al., 2005). the second hypothesis was not supported in that no significant difference was found to exist between males and females (table 3), while later-emerging teeth did exhibit significantly greater asymmetry (table 3) lending support to the third hypothesis related to timing of tooth emergence and degree of eruption asymmetry. heikkinen’s study (1998) derived similar findings with regards to the proportion of symmetrically erupting antimeric pairs, which was found to be approximately 90% in mandibular central incisors, while the maxillary lateral incisors, which are the last teeth to emerge in the first phase of the mixed dentition, showed a symmetrical proportion of approximately 50%. with later-emerging teeth, the proportion of symmetrically erupting antimeres decreased, being the lowest in second premolars. interestingly, the last emerging permanent teeth in the second phase of the mixed dentition, the second molars, appeared to be more symmetric. given that the more distal teeth in each class tend to emerge later in life and spend relatively more time erupting, it is plausible that asymmetry will be greater due to the larger window of opportunity for environmental influences to interfere with the eruption patterns of these teeth. recent research by parner et al. (2002) has reported on the apparent correlation between emergence times of teeth belonging to the same jaw innervation group. the authors also suggested that maxillary teeth may exhibit greater stability as their nerve innervation is more distinct for individual teeth. these findings might then be extended in relation to dental asymmetry patterns. for example, arch-specific findings related to dental asymmetry have shown the maxillary arch to exhibit greater asymmetry compared to the mandibular arch (townsend, 1981; kieser et al., 1986). broader links between prenatal factors and dental eruption patterns have also been identified (garn et al., 1965; heikkinen et al., 1998). heikkinen et al. (1995) found the early clinical eruption of permanent central incisors was slightly affected in children born to mothers who smoked during pregnancy, while garn et al. (1965) explained the large differences found between monozygotic twins as being possibly due to the effects of steroids on root formation and tooth movement. more research investigating the broader links between dental asymmetry patterns and other developmental disturbances should be considered for the future. garn et al. (1967) studied dental crown dimensions in males and females and proposed that increased dental asymmetry observed in males may be related to the presence of only one x-chromosome. females with a pair of x-chromosomes were found to be more symmetrical in tooth size and it was proposed this may be related to p. sobhi et al. 39 the extra x-chromosome leading to increased buffering capacity. as discussed earlier, several studies following garn et al. (1967) do not report significant sex variation. no significant difference between males and females was noted in our study, while more recent studies by heikkinen et al. (1998) do show significant difference by sex with females being more symmetric than males. heikkinen found this pattern for the maxillary lateral incisor and first premolar, and the mandibular central incisor and canine in us children, and for the maxillary first premolar and mandibular central incisor and first molar in finnish children. similar findings with respect to greater symmetry among females have been documented by bailit et al. (1970) and townsend and brown (1980), lending further support to garn’s theory. overall, there appears to be inconsistency in regards to the influence of sex on asymmetry patterns. our fourth hypothesis regarding directionality in tooth eruption was also supported with results indicating left-sided dominance for the maxillary second and third molars and mandibular first molar, and right-sided dominance for the maxillary incisors and mandibular lateral incisors, canines and premolars. while our findings do indicate the existence of directionality, the underlying pattern is less clear. harris (1992) and townsend et al. (1999) suggested left-sided dominance in tooth size in one arch may be associated with rightsided dominance in the opposite arch however this did not seem evident in our sample. for testing the last hypothesis, comparisons were drawn between data from the present study and those from heikkinen et al. (1998) for us and finnish children. overall trends included generally greater eruption symmetry among the finnish and australian aboriginal samples compared to the us african american and caucasian samples. antimeric tooth pairs that were found to exhibit the greatest level of stability across ethnic groups included the early emerging lower central incisors and upper first molars. in almost all cases, the more distal teeth in each morphogenetic field tended to be more asymmetrical across all samples. it is plausible that the upper first molars would show similar trends across samples given that these teeth are important in stabilizing occlusion and are also less likely to be interrupted in their eruption path as they do not succeed primary teeth. however, other results are more surprising. for example, the lower central incisors tend to be more variable than lower lateral incisors in one sample (australian aborigines) but not so for the other three samples. similarly, it is not immediately obvious why the finns and australian aborigines would be more similar in their patterns of symmetry compared with the american samples. a confounding factor in making these comparisons is that each of the three samples was scored by a different researcher. whilst the same scoring system was used in each case, it is possible that inconsistencies exist between scorers. hence, considerable caution should be exercised when making inter-population comparisons of existing data on eruption asymmetry due to these limitations. further studies based on larger sample sizes and consistent methodology across samples are required before true inter-population variation in eruption asymmetry can be described accurately. overall methodological considerations should also be taken into account. the number of subjects included in this study was limited to 90 from a total sample of 450 individuals. many individuals were excluded because of limited numbers of serial casts being available during the mixed dentition phase, and casts for some individuals could not be included because they were damaged or had missing teeth. teeth were scored using the cast on which they first became evident, although subsequent casts, that were usually obtained at annual intervals, were used to confirm presence of teeth and assist in scoring. while limitations of the scoring system were noted, accurate assessment of the degree of eruption was not always possible. there were several teeth that displayed gingival recession or inflamed gingivae, which in turn led to more challenging judgement of whether eruption was full or partial. in some instances, examination of the level of the occlusal plane and physically occluding the upper and lower casts was necessary in order to determine whether a tooth was fully or partially erupted. there were problems in some cases in distinguishing between categories 2 and 3, and categories 3 and 4. it would be worthwhile considering the addition of an extra score(s) to define more precise points of eruption, although this may reduce the level of reliability of scoring. conclusion our findings provide evidence of patterned tooth eruption asymmetry among a sample of australian aborigines with the distally positioned, later-forming teeth showing the highest levels of asymmetry. while directional asymmetry was shown to be present, no clear pattern could be ascertained. despite limitations in making comparisons across different studies, there was some evidence to suggest stability of the upper first molars and the lower central incisors when investigating the influence of ethnicity on asymmetry patterns. acknowledgements the dental casts were collected by the late m. j. barrett during a growth study which was supported by research grant de 02034 from the national institute of dental research, bethesda, md, and by grants from the university of adelaide and the australian institute of aboriginal studies, canberra. ethical approval was obtained at the 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asymmetrical tooth eruption brace and seguchi 2005.6 65 kazuro hanihara 1927–2004 kazuro hanihara, born in fukuoka prefecture on the southernmost japanese island of kyushu, was one of the major figures in biological anthropology in japan. he was especially prominent among japanese anthropologists for his work in dental anthropology, and he regularly voiced his gratitude to that legendary embodiment of dental anthropology, albert a. dahlberg of chicago, for contacts, encouragement, and access to dental collections. among his many contributions was his construction of a measuring device that allowed the researcher to give precise figures for the depth of the lingual fossa in a shovel-shaped incisor. hanihara gained both his undergraduate, 1948-1951, and his graduate, 1951-1956, training in anthropology at the school of science of the university of tokyo. early in his graduate career, he worked for the american military forces at kokura camp in fukuoka prefecture at the task of identification of american soldiers who had died during the korean war. this not only gave him practical experience in forensic anthropology and in the recognition of anatomical features of people of largely european ancestry but, at least as important, it made him comfortable with communicating in the english language. not only was he able to discuss matters in effective english, he could lecture in the language with comfort and ease. much of his anthropological work was published in english, and much of the writing was primarily done by himself and needed only minor editing by a native english speaker. this quickly earned him international recognition that he was to retain for the rest of his life. in 1956, he became an assistant professor in the department of legal medicine at the sapporo medical college on the northern island of hokkaido. his use of mahalanobis d2 distances, discriminant functions, and q-mode correlation coefficients gave the cachet of statistical sophistication to his work, and in 1958, the year he earned his doctor of science degree from the university of tokyo, he was promoted to associate professor at the sapporo medical college. the very next year, as a fulbright exchange scholar, he served as a visiting professor at the university of chicago, a role he filled again in 1968. in 1969, aided by a leverhulme visiting fellowship, he was a visiting professor at the university of adelaide in australia where he studied the dentition of the northern australian aborigines. he also served as a visiting professor at arizona state university in 1984. because of his initial professional location on hokkaido, he became involved in questions concerning the identity of the ainu and their relations to the prehistoric inhabitants of japan and to the majority of the non-ainu japanese. he clearly recognized the similarity fig. 1. kazuro hanihara (right); his wife, kazuko (center); and keiichi omoto (left) at a dinner gathering in the hanihara home following the end of a workshop titled “the origin and past of homo sapiens sapiens as viewed from dna—theoretical approach” that took place on december 14-17, 1993, in the international institute for advanced studies, kyoto, japan. dr. hanihara was the workshop convenor and iias vice-director. (photograph courtesy of christy g. turner ii.) fig. 2. kazuro hanihara: 1924�2004. 66 book review dental functional morphology: how teeth work. by peter w. lucas. new york: cambridge university press, 2004. 372 pages, 7 chapters, 2 appendices. $130.00 £75.00 occasionally in science a novel treatment of a familiar subject opens new vistas for exploration and thought. this is the case with dental functional morphology by peter w. lucas. part dental anthropology and part physics, this book challenges long held paradigms regarding the morphology of mammalian teeth. viewed from the perspective that physical characteristics of food drive selection of tooth form, lucas presents a well thought argument revolving around how dental morphology has evolved in response to the fracture properties of food. the adage “if you don’t eat, you die” can be altered using lucas’ view to “if your teeth don’t efficiently fracture foods and reduce particle size to that which is of the ainu to the prehistoric jōmon. despite his use of sophisticated statistics, however, his conclusions savored more of preconceived notions than of anything that derived from the actual metric data. without actually using odontometric data to test the idea, he debunked the old suggestion that there was a “caucasoid” element in the ainu. as with so many japanese who want to believe that they are descended from the prehistoric inhabitants of the archipelago, he tried to push the idea that the jōmon played a role in the ancestry of the japanese which they did to a varying extent. he recognized the fact that most japanese looked more like mainland east asians than jōmon-ainu people, and he suggested, in the absence of archaeological support, that massive population movements from that mainland had been responsible. his estimate was that more than a million people moved from northeast asia to japan during the time between 300 bce and 700 ce, a guess that has made more than a few prehistorians uneasy and doubtful. in 1972 he returned to the university of tokyo as professor of anthropology in the school of science where he remained until reaching the mandatory retirement age of 60. starting in 1987, he began what was to be a lifelong affiliation with the international research center for japanese studies in kyoto. actually, he was one of the major figures involved in setting up that research center in the first place. in order to make the case to japanese prime minister nakasone for the establishment of that center, hanihara traveled to america in the spring of 1985 and visited a series of universities to gather expressions of support for the project. his efforts were highly successful, and this points out one of the most prominent aspects of kazuro hanihara. he was a marvelous organizer and administrator and was a successful chairman of a museum and department as well as a long series of committees. not only was he admirably well-organized, but he exuded a manifestation of graciousness and charm that clearly nurtured his success. hanihara was probably most known for his proposal of a “dual structure model for the population history of the japanese” first published in 1991. in this, he proposed that the prehistoric jōmon of japan were derived from southeast asia which he sometimes referred to as “south asia” although this did not mean the indian sub-continent as that designation has usually implied. he suggested that a mixture of jōmon and northeast asians gave rise to the ainu on the one hand and the modern japanese on the other. the difference between the two, he proposed, was the result of microevolution in situ. the jōmon themselves he regarded as qualifying as perfectly good “mongoloids” although this was not supported by any kind of metric demonstration. the idea that the ainu represent the continuity of the jōmon with a bit of input from eastern asia is indeed supported by an analysis of common variance, and the idea that the japanese largely represent the morphology of eastern asia tempered by a trace of jōmon form in increasing amounts the farther east one goes in the archipelago is also supported by the variance figures. however, the role of microevolution in leading to the ainu/japanese differentiation has no basis, and there is no evidence supporting a southeast asian locus of origin for the jōmon themselves. last but not least, kazuro hanihara was enormously helpful to visiting scholars who knew little or no japanese. whether he agreed with the interpretation of the results of their work or not, he was unfailingly gracious and supportive. he figured out bus and train schedules, helped people get to the right stations, he met planes, and made hotel reservations, and many more much appreciated acts of generosity and assistance. for those of us who counted him as a friend, his passing leaves a real sense of loss. c. loring brace museum of anthropology university of michigan ann arbor, mi, 48109 usa and noriko seguchi department of anthropology university of montana missoula, mt, 59812 usa jones 1996.1 cooke 2002.4 60 61book review primate dentition: an introduction to the teeth of non-human primates. by daris r. swindler. united kingdom: cambridge university press (hardback), 2002. 294 pp. isbn 0-521-65289-8. $80.00 daris swindler’s update to his 1976 publication, dentition of non-human primates, presents a comprehensive database of the dentition of 85 living primate species. the book includes morphological and metrical descriptions as well as an overview of basic concepts in tooth anatomy, morphology, and histology. throughout the text, swindler provides comparative analyses and techniques for age estimation and stresses the value of dentition for understanding phylogeny and ontogeny. the text begins with background on dentition and includes a chapter on deciduous dentition. the core of the book features dental measurements and descriptions organized taxonomically. this excellent resource offers not only an introduction to non-human primate dentition but also acts as starting point for further research. chapter one reviews basic information on the order primates and the methods of odontometry used throughout the text. all measurements were taken from museum specimens, and swindler focuses on the normal range of variation in the dentition. the first chapter introduces the reader to the terms of position and the cope-osborn cusp terminology both visually and in the text. the diagrams are particularly useful for those unfamiliar with tooth terminology. swindler also includes a table of synonyms for the cope-osborn nomenclature. in chapter two, swindler discusses dental anatomy and devotes sections to enamel, dentine, cementum, the tooth root, and pulp. within each topic, swindler outlines the composition, histology, and formation of each component while also integrating topics of current research. the enamel section features a discussion of the study of enamel microstructure, enamel hypoplasias, and cross-striations and their ontogenetic and phylogenetic implications. swindler also highlights often neglected areas of inquiry including the microanatomy of dentine and cementum lines. chapter three provides a brief overview of dental development. swindler discusses two theories for the development of heterodont tooth morphology―the morphogenetic field theory and the clone model. the text covers odontogenesis, ontogeny of crown patterns, and stages of permanent tooth formation. drawings and photographs clarify and supplement the discussion. in the section on age estimation, swindler emphasizes the idea that tooth formation may give a better indication of age than tooth emergence. an exceptionally noteworthy contribution is the chapter four discussion of deciduous dentition, a topic widely covered for human dentition but not for nonhuman primates. swindler provides measurements and comparative analyses of the few specimens available for study. within each section, swindler provides written descriptions and detailed drawings and uncovers intriguing trends in dental development. for example, swindler detects the presence of an underbite in the deciduous dentition of leaf-eating primates, alouatta and colobus. the condition occurs into adulthood, which suggests a genetic component for its presence. the remainder of the text covers the morphological and metrical descriptions. brief discussions of distribution and habitat, general dental information, and diet precede the morphological observations in each chapter. the general dental section features comparative analyses and identifies evolutionary trends for each group of non-human primates. swindler also discusses the degree of sexual dimorphism in the dentition. the text includes detailed drawings of a majority of the species measured and illuminates the variations in dental features. swindler devotes chapter five to the suborder prosimii with separate sections for each family. he incorporates such issues as the debate over the function of the dental comb into the morphological descriptions. chapter six covers the superfamily ceboidea. a diagram of canine-incisor relations in the marmoset and the tamarin clearly illustrates the differences in canine size and the variations between species. chapter seven focuses on cercopithecidae and includes a discussion on enamel thickness in relation to diet and the origin of the bilophodont molar. a short chapter on hylobatidae follows. the discussion features a definition of the y-5 molar pattern and its variations. the coverage of the y-5 pattern continues in chapter nine, which is devoted to pongidae. the chapter includes a table of the mandibular groove patterns and cusp number showing slight deviations from the standard configuration. swindler also discusses the variable appearance of the deflecting wrinkle and two extra cusps, the tuberculum sextum and tuberculum intermedium, in hominoid mandibular molars. the appendices at the end of the book provide further reference resources. appendix 1 features the odontometric information for the permanent and deciduous teeth (when available) of each species studied in the text. for each species, a table for the maxillary and mandibular teeth is presented with the number of specimens, the mesiodistal and buccolingual measurements for each tooth, t-test results for sexual dimorphism, and the range of measurements. additionally, the tables include the presence/absence of a hypoconulid and the corresponding information. appendix 2 provides the dental eruption sequences of the mandibular and maxillary teeth for all the species discussed in the book. when available, swindler includes data for both sexes. the information is useful 60 61 not only for aging individuals but also for ascertaining life history patterns. the text also features a glossary at its conclusion. primate dentition serves as an essential resource for students and professionals in dental anthropology, primatology, and comparative anatomy. the diagrams and definitions prevent the text from becoming overwhelming for students but also not too rudimentary for more advanced readers. swindler provides a valuable summary of current knowledge in non-human primate dentition and prompts further investigation in the field. cathy cooke the ohio state university book review the annual meeting of the canadian association for physical anthropology will be held in edmonton, alberta, october 23-25 of 2003. contributed papers and posters for a symposium on dental anthropology are welcome. for further information, contact dr. nancy lovell, department of anthropology, university of alberta, edmonton, t6g 2h4 canada. e-mail: nancy.lovell@ualberta.ca capa meeting carrero 1997.4 pg11.jpg pg12.jpg pg13.jpg pg14.jpg pg15.jpg pg16.jpg pg17.jpg pg18.jpg pg19.jpg walker 1997.1 pg1.jpg pg2.jpg graver 2005.2 12 13 the biological impact of european exploration and expansion had varied consequences on the health of native populations in the new world (baker, 1994; baker and kealhofer, 1996; larsen and milner, 1994; larsen et al., 2001; pfeiffer and fairgrieve, 1994; ubelaker, 1993; verano and ubelaker, 1992). health effects differed according to several factors, including the motivation of european explorers (e.g., religious or economic), duration of contact, and native cultural and physical environments (baker and kealhofer, 1996; larsen and milner, 1994; larsen, 2001; ubelaker and curtin, 2001; verano and ubelaker, 1992). previous historical and archaeological literature has emphasized the negative consequences of contact for both immigrant and native populations, concentrating on disease and epidemics (e.g., cook and lovell, 1991; crosby, 1986; dobyns, 1983, 1993; sale, 1990). more recent work has demonstrated that biocultural responses to contact were not uniform, and that native populations adapted differently to post-contact conditions (baker and kealhofer, 1996; larsen, 1994; larsen and milner, 1994). few bioarchaeological analyses have focused dental health decline in the chesapeake bay, virginia: the role of european contact and multiple stressors sally m. graver* department of anthropology, the ohio state university, columbus, ohio *correspondence to: sally graver, department of anthropology, 244 lord hall, 124 w. 17th street, the ohio state university, columbus, oh 43210. e-mail: graver.8@osu.edu abstract: this study tests the hypothesis that the arrival of europeans in jamestown, virginia, had a negative impact on the dental health of native populations in the chesapeake bay. data were collected on three variables—dental caries, periapical lesions, and antemortem tooth loss—in a sample of 644 individuals from four prehistoric (n = 500) and two contact era ossuaries (n = 144) from the potomac creek site in virginia (44st2). statistical analysis reveals a trend of declining dental health for the post-contact sample (chi-square; p<0.05). the temporally latest ossuary had the highest prevalence of all indicators. there is also a trend toward poor dental health for females relative to males. in particular, females have a higher prevalence of carious lesions and antemortem tooth loss than males. sex differences in dental health probably correspond to sex-based differences in food production and preparation in this setting, since females likely ate more cariogenic foods. multiple factors likely explain the general pattern of decline in dental health, including: (1) a change in diet involving greater consumption of carbohydrates, (2) increased exposure to infectious pathogens, (3) warfare and other forms of conflict, (4) strain on resources, and (5) increased population density. dental anthropology 2005;18:12-21. editor’s note: ms. graver’s paper was awarded “first runner up” for 2005 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. sally graver (left) receiving dahlberg award from daa president debbie guatelli-steinberg. 12 13 on issues of contact in the chesapeake bay region (but see mecklenburg, 1969; miller et al., 1999), where long term contact commenced with the founding of jamestown by british colonists in 1607 (dent, 1995). in order to completely understand the contact experience in north america, it is important to document this cultural encounter. the purpose of the present study is to test the hypothesis that contact with english settlers resulted in a decline in the dental health of native populations in the chesapeake bay. in order to test this hypothesis, the dental remains of a patawomeke indian population originating from four prehistoric and two contact era ossuaries at the potomac creek site in virginia (44st2) were examined (fig. 1). the population under study is known historically to have had an intimate relationship with the jamestown colonists and represents an excellent population sample on which to test this hypothesis. data were collected for three dental health indicators: dental caries, periapical lesions, and antemortem tooth loss in order to assess whether a decline in dental health occurred in the chesapeake bay during the transition from the late prehistoric period to the contact era. dental health indicators dental caries is a pathological process resulting in destruction of tooth structure by acid-forming bacteria found in dental plaque (hillson, 2000; national library of medicine, 2001; schachtele, 1990). populations with diets high in carbohydrates or other dietary sugars (such as maize) are predisposed to dental caries and poor oral health in general (hillson, 2000; hutchinson and larsen, 2001). this positively correlated relationship is well documented in both bioarchaeological and medical literature (larsen, 1983; lukacs, 1992; newbrun, 1982; schachtele, 1990; turner, 1979; walker and hewlett, 1990). furthermore, caries rates have been relatively low throughout prehistory until the adoption of agriculture and, thus, the addition of cariogenic foods into the diet (hillson, 2000; larsen, 1995; larsen et al., 1991). increases or decreases in caries rates can document dietary change in prehistory (hillson, 2000; larsen, 1997). caries is a slowly progressive, age-related disease. therefore, age data are important for understanding caries frequencies. caries rates are also typically higher in molars and premolars (hillson, 2001). this disease results when the cariogenic component of the diet is increased and constant (schachtele, 1990). anthropological literature commonly uses the term “abscess” to refer to periapical lesions in the alveolar bone; however, abscess formation is only one of several possible inflammatory responses (alt et al., 1998; dias and tayles, 1997; hillson, 2000). the differential diagnosis of periapical lesions in prehistoric populations is a problematic; therefore, periapical granulomata, cysts, and abscesses collectively are classified here as lesions. periapical inflammation of the alveolus results from soft tissue infection where bacteria spread and cause pulp chamber inflammation (pulpitis) (hillson, 2000). this inflammation is usually painful and can be due to a number of factors, including excessive dental wear, carious lesions, periodontitis, dental impactions, tooth fracture, or pulp chamber exposure (buikstra and ubelaker, 1994; dias and tayles, 1997; hillson, 2000; larsen, 1997). the alveolar process has very active bone remodeling at all ages (hillson, 2000; verna et al., 1999). when a tooth is lost during life, the alveolus gradually resorbs the socket and remodels bone to create a smooth flat surface where the tooth had been before it was lost. in archaeological populations, periapical inflammation and abscesses generally result in the loss of teeth and eventual resorption of the alveolus (hillson, 2000; larsen, 1997). other factors that may contribute to tooth loss during life include chipping or breakage, extraction, wear, periodontal disease, or trauma (hillson, 2000). biocultural setting a decline in the dental health of native americans has been documented elsewhere in north america after european contact (e.g., baker, 1994; hill, 1996; kelley et al., 1987; larsen et al., 2001; stodder and martin, 1992; walker and johnson, 1992, 1994). while the motivations of the spanish, french, and english in the new world varied, the effects of their colonization on native populations share some common outcomes. throughout north america, exposure to european diseases reached epidemic proportions and drastically reduced native population size (baker, 1994; baker and kealhofer, 1996; brose et al., 2001; fitzhugh, 1985; larsen, 2001; larsen and milner, 1994; larsen et al., 2001; pfeiffer and fairgrieve, 1994; ubelaker, 1993; ubelaker and curtin, 2001; verano and ubelaker, 1992). other studies, however, indicate that late prehistoric levels of dental pathology were already high due to the intensification of agriculture, and that contact with europeans did not necessarily affect the dental health of natives (cybulski, 1994; hutchinson and larsen, 2001; miller, 1996; pfieffer and fairgrieve, 1994; reinhard et al., 1994; stodder, 1996). for instance, pfieffer and fairgrieve (1994) found no significant difference in caries prevalence, abscesses, and linear enamel hypoplasias between prehistoric and post-contact iroquois ossuaries. although evidence suggested that episodic stress and disease prevalence increased from the late prehistoric to postcontact times, the authors were reluctant to conclude european contact was solely responsible for the trend in declining health over time. chesapeake bay dental health 14 15 european-introduced diseases may have devastated chesapeake natives, although sources disagree about the scope of this phenomenon. european accounts from the 17th and 18th centuries offer conflicting accounts about the health of native populations in the chesapeake, leading some historians to claim that no major epidemics occurred around the time of contact (e.g., potter, 1993; rountree, 1990; turner, 1985). other scholars suggest it is impossible to ignore the impact of european diseases on native populations (dent, 1995; rountree, 1989; ubelaker, 1993; ubelaker and curtin, 2001). early jamestown colonists gabriel archer and william strachey claim that native groups were ravaged by disease, most likely smallpox (archer, 1969; strachey, 1953; ubelaker and curtin, 2001). chesapeake natives were almost certainly subjected to repeated epidemics of smallpox, measles, whooping cough, typhoid, mumps, syphilis, influenza, plague, and scarlet fever, which greatly decreased population size in the 16th and 17th centuries (ubelaker, 1993; ubelaker and curtin, 2001). europeans arrived in the chesapeake at a time when population pressure, drought, declining health, and conflict were widespread (potter, 1993; rountree, 1989). tree-ring data from virginia and sediment cores from the chesapeake indicate that two severe droughts, the first occurring prior to contact (ad 1587-1589) and the second just after the settlement of jamestown (ad 1606-1612), would have been devastating to native subsistence practices (cronin et al., 2000; richardson et al., 2002; rountree, 1989; stahle et al., 1998). the second severe drought has been suggested as a possible contribution to the deaths of 70 of the 104 colonists during the first year of settlement at jamestown and to high mortality during the next decade (blanton, 2000; richardson et al., 2002, stahle et al., 1998). natives were accustomed to minor droughts every three years (rountree and turner, 2002), but were not prepared to share resources with europeans during a severe drought. with contact came new problems for native populations that would inevitably change their way of life. archaeological data indicate that an increase in native population growth and the development of chiefdoms brought prehistoric native groups into conflict. new alliances and trade with europeans were also disruptive to native political systems, often pitting native groups against each other (axtell, 1988; dent, 1995; potter, 1993). the arrival of the jamestown colonists made competition for resources more acute. one strategy for survival was to cooperate with the new immigrants. the patawomeke employed such a strategy by allying themselves with the british against their old rivals, the more powerful powhatan (potter, 1993). subsistence the intensification of domesticated plants, specifically maize, negatively impacted the health of native groups in the chesapeake bay (hoyme and bass, 1962; ubelaker, 1993). a maize-based diet is marginally sufficient in protein, vitamins, and minerals, depending on processing techniques and supplemental foods (messer, 2000). additionally, maize is low in the essential amino acids lysine and tryptophan as well as calcium and niacin (ensminger et al., 1995; messer, 2000). without adequate supplementation, a maizebased diet is deficient in iron, due to the presence of phytates that inhibit the absorption of iron by body tissues (baynes and bothwell, 1990). the negative effects of a diet high in maize can be clearly observed in a comparison of inland and coastal skeletal samples in the chesapeake region. chase (1988) found that coastal populations exhibited less evidence of anemia (porotic hyperostosis and cribra orbitalia) than the inland populations. she argued that this difference was due to the higher level of marine resources available to coastal populations, which can offset the problems associated with maize (chase, 1988; messer, 2000; papathanasiou et al., 2000). stable isotope data confirm this hypothesis. fig. 1. map of the chesapeake bay, with location of potomac creek site. modified from ubelaker, 1974:12. s. m. graver 14 15chesapeake bay dental health an analysis of stable carbon and nitrogen isotopes from late woodland skeletal samples from virginia demonstrate that maize comprised a significant proportion of diets from all regions (25-50% in the coastal plain), while only the coastal populations had significant marine resources incorporated in the diet (trimble, 1996). fourteen individuals sampled from the population under study were compared to other coastal plain, piedmont, and appalachian populations from the late woodland period. of the 15 sites sampled, potomac creek populations had the lowest mean δ13 c and δ15 n values, indicating that their diet consisted of the highest proportion of marine or freshwater resources (trimble, 1996). trimble (1996) argues that maize contributed about 20 to 50% of the patawomeke diet, and that prehistoric c 4 plant usage at potomac creek was lower than the other 14 sites. studies have also shown a positive correlation between a maize-based diet and high caries rates in prehistoric populations (cook, 1984; larsen, 1995, 1997; larsen et al., 1991). the traditional method of preparation in the chesapeake bay included grinding and boiling maize into a soft gruel (smith, 1986a). the preparation of maize into a sticky, starchy mush increases the likelihood that food particles will become caught in tooth grooves during mastication, which make teeth more prone to dental caries (cook, 1984; reeves, 2001). moreover, maize-based diets show strong association with poor health, including high frequencies of antemortem tooth loss, iron-deficiency anemia, and periapical lesions (baynes and bothwell, 1990; cook, 1984; cohen and armelagos, 1984; larsen, 1995, 1997; larsen et al., 1991). a poor diet, such as one that emphasizes maize without sufficient supplementation of iron and protein, results in poor nutrition, which leads to a greater susceptibility to infection and disease (ensminger et al., 1995; messer, 2000, powell, 1988). materials and methods the sample consists of a minimum number of 644 individuals from the potomac creek site (44st2), which is located on the western shore of the potomac river in stafford county, virginia (fig. 1). the remains are curated at the national museum of natural history, smithsonian institution, washington, d.c. two of the burial contexts contain european trade items that indicate use of the site during post-contact times. the sample (n = 644) consists of four pre-contact (<ad 1607; n = 500) and two post-contact (>ad 1607; n = 144) ossuaries. an ossuary involves a mortuary practice that is defined as the “collective, secondary deposit of skeletal material representing individuals initially stored elsewhere” (ubelaker, 1974:8). ossuaries should not be confused with mass burials, as the latter implies that individuals died around the time of their deposit. because of their commingled nature, ossuaries present several unique problems to bioarchaeologists. demographic profile demographic information was difficult to determine in this sample due to the disarticulated, commingled, and highly fragmentary nature of the remains. age and sex were based on dental development, dental wear, and sexually dimorphic cranial features (table 1). except for ossuary 5, all samples are represented by a small percentage of juveniles and an abundance of table 1. demographic distribution by ossuary temporal period ossuary males females indeterminate juveniles total n % n % n % n % n post-contact multiple burial pit 2 29 0 0 2 29 3 42 7 post-contact ossuary 1 20 15 10 7 102 74 5 4 137 pre-contact ossuary 2 69 21 56 17 176 54 22 8 323 pre-contact ossuary 3 7 15 8 17 28 61 3 7 46 pre-contact ossuary 4 0 0 0 0 18 86 3 14 21 pre-contact ossuary 5 30 27 29 26 13 12 38 35 110 fig. 2. average wear score by ossuary. wear scores are based on the eight-grade system developed by smith (1984), with grade 1 being no wear. 0 10 20 30 40 50 60 70 1 2 3 4 5 6 7 8 9 wear score n um be r o f i nd iv id ua ls multiple burial ossuary 1 ossuary 2 ossuary 3 ossuary 4 ossuary 5 16 17 adults of indeterminate sex. data collected on juvenile permanent dentition were pooled with adults for dental caries only. since other bone elements could not be associated directly with crania or isolated teeth, an estimate of adult age is provided by an analysis of dental wear (fig. 2). studies have shown a strong correlation between age and dental wear in archaeological populations (smith, 1984; walker et al., 1991). dental wear was scored following the eight stages proposed by smith (1984) for all individuals and loose teeth by ossuary. due to the high degree of postmortem tooth loss, an average wear score of all present teeth was calculated for complete sets of dentition; loose teeth were scored on an individual basis. these data are provided to identify possible confounding factors in the analysis of age-related dental pathological indicators: dental caries, antemortem tooth loss, and periapical lesions (hillson, 2000). dental health indicators carious lesions were recorded for each tooth by number of carious lesions per tooth and location of lesions. periapical lesions were identified by the presence of a drainage channel leading from the apex of the tooth root through the alveolar bone, resulting in a granuloma, cyst, or abscess (buikstra and ubelaker, 1994; dias and tayles, 1997). antemortem tooth loss could only be determined from direct observation of alveolar bone of the maxilla and mandible. tooth loss was documented when the associated alveolar bone was partially or totally resorbed. statistical analysis chi-square statistics were applied to the data set in order to test for significant differences between samples. for each dental health indicator, statistical tests were conducted among ossuaries, between combined preand post-contact samples, and within each ossuary (by sex). due to the commingled and fragmentary nature of the remains, it was impossible to separate the samples by age categories other than adult and juvenile. results dental caries dental caries rates are high among adults (table 2) from all burial samples. a comparison of combined burial samples (including adults and juvenile permanent dentition) demonstrates significantly greater caries rates in the post-contact sample than in the pre-contact ossuaries (fig. 3). two ossuaries show significant variation between the sexes: ossuary 2 females have higher caries rates for molars than males and ossuary 5 females have greater overall caries rates than males. periapical lesions although periapical lesions were relatively few among all samples, lesion prevalence is significantly greater in the pre-contact sample (fig. 3, table 3). sex differences within samples indicate that males have a higher lesion prevalence than females. table 2. prevalence of adult carious lesions per tooth class um up uc ui lm lp lc li total ossuary n % n % n % n % n % n % n % n % n % mbp 4 33 0 0 5 100 2 40 2 33 4 50 0 0 1 7 18 30 1 78 43 26 18 12 16 23 21 111 55 41 26 19 22 7 8 317 31 2 207 43 92 28 30 19 28 16 213 53 77 24 19 12 14 7 680 31 3 16 27 11 18 3 10 1 5 18 38 1 33 2 12 0 0 52 19 4 4 30 1 13 1 50 0 0 3 25 1 14 1 50 0 0 11 23 5 68 33 38 23 14 15 11 9 88 49 34 20 6 6 4 3 263 23 fig. 3. prevalence of dental health indicators by temporal period. s. m. graver 0 5 10 15 20 25 30 35 periapical lesions dental caries antemortem tooth loss pre post 16 17 antemortem tooth loss antemortem tooth loss is common for adults in all samples (table 3). significant differences do not exist between pre-contact and post-contact samples (fig. 3); however, post-contact males have greater posterior tooth loss than pre-contact males. comparisons by sex among ossuaries indicate that females consistently have higher levels of antemortem tooth loss than males. discussion the results of this research are summarized as follows. except for ossuary 5, all samples are represented by a small percentage of juveniles and an abundance of adults of indeterminate sex. juvenile data were only collected for dental caries and were pooled with adults for the permanent dentition only. the post-contact multiple burial pit consistently had the highest prevalence of dental pathological indicators for each category. however, this sample is the smallest (n = 7), so less confidence should be placed in these results. ossuary 1, the other post-contact sample, had lower than expected prevalence data for dental health indicators. the lower lesion prevalence for ossuary 1 may be due to the younger age composition of the adults in this sample. the combined post-contact samples had significantly greater caries prevalence than the pre-contact sample. the pre-contact sample had more periapical lesions than the post-contact sample, and there were no differences between preand post-contact samples for antemortem tooth loss. there was a trend towards higher caries rates and antemortem tooth loss for females, and higher periapical lesions prevalence for males. an appraisal of the demographic distribution of the ossuaries from the potomac creek site reveals considerable variation. the small sample size and lack of available sex data precluded some comparisons with the multiple burial pit and ossuary 4. tooth wear estimates for each burial sample reveal that ossuary 1 and ossuary 2 have more young adults than older adults, while the converse is true for the sample from ossuary 5. therefore, age may be a confounding factor in prevalence data for ossuaries 1, 2, and 5. dental caries at the potomac creek site, caries rates increased after contact with the jamestown colonists. an increase in caries rates after european contact has been documented elsewhere in the new world after contact. for example, larsen and colleagues (1991) suggest that the post-contact increase in caries rates for native populations in la florida was due to increased production and consumption of maize, concomitant with the change to a mission lifestyle. the patawomeke were probably producing more maize as well, since they supplied maize and other foods to the colonists on several occasions (potter, 1993). the trend of higher caries rates for females is not uncommon in populations dependent upon maize. studies show higher caries rates for females in agricultural populations in the new world, probably due to sex-based differences in food preparation and consumption (hillson, 2000; larsen et al., 1991). periapical lesions contrary to the expected results, periapical lesion prevalence decreases after contact. it is often difficult to identify the cause of periapical lesions, but its etiology is commonly linked to dental caries and severe dental wear (hillson, 2000). a number of possible causes for the higher rates of periapical lesions among the precontact population can be proposed: 1) a change in diet associated with contact, 2) poorer oral hygiene, or 3) more abrasive foods in the diet (causing more dental wear). males display more periapical lesions in half of the samples from the potomac creek site. these results are unexpected due to the higher caries rates in females and ethnohistoric evidence for females consuming more cariogenic foods. a possible explanation for this difference is a higher rate of antemortem tooth loss among females; if females are losing more teeth, or losing them earlier than males, it is likely that the prevalence of periapical lesions would be lower among females. antemortem tooth loss antemortem tooth loss appears not to have changed over time. however, a comparison of male posterior teeth demonstrates that antemortem table 3. periapical lesion and antemortem tooth loss prevalence for adults by ossuary and combined samples periapical antemortem lesions tooth loss ossuary n % n % mbp 8 13 21 35 1 34 3 256 19 2 251 7 785 19 3 5 4 49 10 4 103 7 10 8 5 42 3 371 24 post-contact 42 3 277 19 pre-contact 409 7 1215 19 chesapeake bay dental health 18 19 tooth loss did increase after contact. these results approximate the expected outcome for this analysis. furthermore, in three of the samples (ossuaries 2, 3, and 5), females had significantly higher rates of tooth loss than males, possibly elucidating the unexpectedly higher periapical lesion prevalence among males. a greater rate of antemortem tooth loss among females is consistent with the sex-based differences in diet. conclusions the dental pathological indicators used in this study provide information about diet, nutrition, and physiological stress among the patawomeke and insight into the dental health of this population. this research suggests that the arrival of europeans in the chesapeake bay had a profound impact on the dental health of native populations. it was expected that the patawomeke populations would have been acutely affected since they dealt first-hand with europeans, as both allies and, at times, enemies. the patawomeke often provided the major source of subsistence to the europeans, trading bushels of corn for copper, beads, and other non-food items (potter, 1993; smith, 1986b). the trading of valuable food resources would have put a strain on native populations. english colonists also resided in close proximity to the patawomeke on several occasions (potter, 1989), especially in times of war with the powhatan. the close quarters may have facilitated the spread of diseases to which natives were not immune, and would have put a strain on their subsistence resources and daily activities. this study reveals significant differences in all three dental pathological indicators between sexes, a phenomenon that has been observed in other agricultural populations (e.g. cohen and armelagos, 1984). a post-contact decline in dental health and dietary quality has also been documented in many regions of north america, including the northeast (baker, 1994), the south (hill, 1996), the southwest (stodder and martin, 1992), and the west (walker and johnson, 1992). other studies, however, indicate that late prehistoric levels of dental pathology were already high due to the intensification of agriculture, and that contact with europeans did not affect the dental health of natives (miller, 1996; pfieffer and fairgrieve, 1994; reinhard et al., 1994). the results of this study support the hypothesis that native american dental health declined after contact with europeans in the chesapeake bay. this research suggests that the dental health of the patawomeke of the potomac creek site declined following founding of jamestown due to multiple factors, including: (1) a change in diet, (2) exposure to new diseases, (3) warfare or conflict, (4) strain of resources, and (5) increased population density. acknowledgments i would like to thank the smithsonian institution for permission to access the skeletal remains housed in the national museum of natural history. in addition, i would like to acknowledge clark spencer larsen, debbie guatelli-steinberg, paul sciulli, sam stout, tracy betsinger, and kimberly williams from the ohio state university for their suggestions and assistance with manuscript preparation. special thanks are due to douglas ubelaker and dave 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alepotrypa cave, diros, greece. int j osteoarchaeology 10:210-228. chesapeake bay dental health 20 21 pfieffer s, fairgrieve si. 1994. evidence from ossuaries: the effect of contact on the health of iroquoians. in: larsen cs, milner gr, editors. in the wake of contact: biological responses to conquest. new york: wiley-liss, p 47-62. potter sr. 1989. early english effects on virginia algonquian exchange and tribute in the tidewater potomac. in: wood ph, waselkov ga, hatley mt, editors. powhatan’s mantle: indians in the colonial southeast. lincoln: university of nebraska press. p 151-172. potter sr. 1993. commoners, tribute, and chiefs: the development of algonquian culture in the potomac valley. charlottesville: university press of virginia. powell, ml. 1988. status and health in prehistory: a case study of the moundville chiefdom. washington, dc: smithsonian institution press. reeves m. 2001. dental health at early historic fusihatchee town: biocultural implications of contact in 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american adaptation in the spanish borderlands. gainesville: university press of florida, p 148-176. stodder alw, martin dl. 1992. health and disease in the southwest before and after spanish contact. in: verano jw, ubelaker dh, editors. disease and demography in the americas. washington, dc: smithsonian institution press, p 55-74. strachey w. 2001. the historie of travell into virginia britania (1612). in: hadfield a, editor. amazons, savages, and machiavels : travel and colonial writing in english, 1550-1630 : an anthology. oxford: oxford university press, p 296-302. trimble cc. 1996. paleodiet in virginia and north carolina as determined by stable isotope analysis of skeletal remains. m.a. thesis, department of environmental sciences, university of virginia, charlottesville. turner cg ii. 1979. dental anthropological indications of agriculture among jomon people of central japan. am j phys anthropol 51:619-636. turner er iii. 1985. socio-political organization within the powhatan chiefdom and the effects of european contact, ad 1607-1646. in: fitzhugh ww, editor. cultures in contact: the european impact on native cultural institutions in eastern north america a.d. 1000-1800. washington: smithsonian institution press, p 193-224. ubelaker dh. 1974. reconstruction of demographic profiles from ossuary skeletal samples: a case study from the tidewater potomac. washington, dc: smithsonian contributions to anthropology, no 18. ubelaker dh. 1993. human biology of virginia indians. in: rountree hc, editor. powhatan foreign relations. charlottesville: university press of virginia, p 53-75. ubelaker dh, curtin pd. 2001. human biology of populations in the chesapeake. in: curtin pd, brush gs, fisher gw, editors. discovering the chesapeake: the history of an ecosystem. baltimore: johns hopkins university press, p 127-148. verano jw, ubelaker dh, editors. 1992. disease and demography in the americas. washington, dc: smithsonian institution press. verna c, melsen b, melsen f. 1999. differences in static cortical bone remodeling parameters in human mandible and iliac crest. bone 25:577-583. walker pl, hewlett bs. 1990. dental health diet and social status among central african foragers and farmers. am anthropol 92:383-398. s. m. graver 20 21chesapeake bay dental health daa web site updated and expanded thanks to the efforts of sally graver (ph.d. student, ohio state university), the dental anthropology association web site has a new home. the new web site address is: http://monkey.sbs.ohio-state.edu/daa/index.htm this is located on the ohio state university department of anthropology’s server. notice that this address is different from that published in the last issue—and should be more robust. alma adler designed the web site, which currently has links to the membership form, dahlberg prize announcement, and to phil walker and ed haagen’s quick-time movies of the dentition. in addition, we have begun providing back issues of dental anthropology on our web site as pdf files. the dental anthropology association is making these available as a professional courtesy to all interested parties—the site is not passwordprotected. after downloading onto your computer, these files will open using version 6.0 or later of adobe acrobat. each file is one issue of the journal. we developed these in one of two ways. for the older issues that had not been saved in electronic format, hard copies were scanned (at 300 dpi). the newer issues were generated using adobe indesign and then converted to pdf files. the newer issues (from vol. 15 no. 2) contain color figures. to facilitate downloading, file sizes were, however, aggressively down-sampled. if you have problems with the resolution or encounter other problems with the files, please contact the editor (eharris@utmem.edu). as of this writing, volumes 13 through 17 are available at our web site. the older issues will be added over the next few months. please visit the site and let us know what you think! walker pl, johnson jr. 1992. effects of contact on the chumash indians. in: verano jw, ubelaker dh, editors. disease and demography in the americas. washington, dc: smithsonian institution press, p 127-140. walker pl, johnson jr. 1994. the decline of the chumash indian population. in: larsen cs, milner gr, editors. in the wake of contact: biological responses to conquest. new york: wiley-liss, p 109-120. walker pl, dean g, shapiro p. 1991. estimating age from tooth wear in archaeological populations. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, p 169-178. harris and buck 2002.3 14 15 tooth formation proceeds in a highly regimented fashion, and the developmental status of formative teeth can be used to assess a child’s dental age, which is one measure of his degree of biological maturity. tanner et al. (1975) comment that, “maturity differs in an important way from a measurement such as stature, in that the normal growth process takes every individual from one common condition of being wholly immature to another of being wholly mature.” various tissue systems have been used to determine biological age; the most common techniques depend either on formation of the teeth (so-called dental age), the morphological development of a set of bones, notably those in the hand and wrist (bone age), and the onset of secondary sexual characteristics (pubertal age; marshall et al., 1969, 1970). dental and bone ages have the advantage that their applicability extends over much of a person’s growth span from fetal life through late adolescence. formation of the teeth is useful for a variety of reasons. the degree of crown-root formation can be viewed directly on skeletal material (both recent and archeological; owsley and jantz, 1983; conroy and vannier, 1987; liversidge, 2000) and analogously on living subjects (e.g., crossner and mansfield, 1983. tooth formation spans almost two decades when the primary and permanent teeth are combined along with the variable third molars (harris, 2002). additionally, tooth formation appears to be under substantial genetic control (pelsmaekers et al., 1997; merwin and harris, 1998)—more so than bone age (e.g., garn et al., 1965; keller et al., 1970). moorrees, fanning and hunt (mfh) published the first standards for tooth formation derived from a large series of children followed longitudinally. longitudinal data are requisite to identify the timing of onset of a stage (smith, 1991). the mfh standards have been applied broadly and still are commonly cited despite their narrow ethnic base (americans of western european extraction) and the possibility of secular effects speeding up the tempo of tooth formation since the mfh data were collected beginning in the 1930s (nadler, 1998). moreover, the long absence of comparable data from other groups of caucasians has led to a de facto assumption of homogeneity in the growth tempo of contemporary humans. that is, since only the mfh data were available for decades, it was presumed that these standards were applicable globally. more recent studies of other groups has disclosed important systematic differences in the tempos of growth among populations (e.g., fanning and moorrees, 1969; haavikko, 1970; anderson et al., 1976; harris and mckee, 1990; liversidge and molleson, 1999) as well as in the sequencing of tooth formation (tompkins, 1996). a technical difficulty in using the mfh data is that the information was only published in graphical format; there was no supporting table of descriptive statistics. this obliged users to plot each of their cases on a graph, which is tedious, impractical if sample sizes are large, and still required interpolation of the graph to a numerical value of “dental age.” also, the graphs cannot be used to computerize the methodology (cf. demirjian et al., 1973). the two-fold purpose of the present note is to supply tables of descriptive statistics for the mfh data and to comment on the nature and limitations of these classic data. materials and methods moorrees, fanning and hunt (1963) scored the formation of 10 teeth from oblique jaw radiographs. these were the maxillary incisors (i1, i2) and all eight mandibular tooth types (i1 through m3). the other maxillary teeth were excluded because superimposition of the complex bony structures of the midface interfered with their consistent visualization on the radiographs. mfh combined two collections of growth data for their study. children with chronological ages prior to about 10 years were obtained from headfilms that had tooth mineralization: a technical note on the moorrees-fanning-hunt standards edward f. harris 1 and andrea l. buck 2 1 department of orthodontics, college of dentistry, university of tennessee, memphis, tennessee 38163 2 osteological research consutling associates, phoenix, arizona 85048 abstract one of the largest, longitudinal studies of tooth mineralization is that described by moorrees, fanning and hunt (j dent res, 1963) based on children growing up in boston, massachusetts, and yellow springs, ohio. this short communication provides correspondence to: e. f. harris, department orthodontics, university of tennessee, memphis, tn 38163 e-mail: eharris@utmem.edu tables of the means and standard deviations, by sex, in order to make the data more accessible and usable than the graphic form of the information in the original article. characteristics of the study and applications are discussed. 16 17 table 1. age at attainment (years) of stages of crown-root formation of permanent incisors1 ui1 ui2 li1 li2 grade sd sd sd sd girls ci • • • • • • • • cco • • • • • • • • coc • • • • • • • • cr 1/2 • • • • • • • • cr 2/3 • • 4.6 0.51 • • • • cr 3/4 • • • • • • • • cr c 4.9 0.54 5.7 0.62 • • • • r 1/4 6.0 0.66 6.6 0.71 4.5 0.51 4.7 0.53 r 1/3 • • • • • • 5.2 0.57 r 1/2 6.6 0.71 7.2 0.76 5.1 0.57 5.9 0.65 r 2/3 7.1 0.76 7.7 0.82 5.6 0.62 6.3 0.68 r 3/4 7.6 0.81 8.3 0.87 6.1 0.66 6.7 0.72 r c 8.2 0.86 9.1 0.95 6.6 0.72 7.6 0.80 a 1/2 8.9 0.93 9.6 0.99 7.4 0.79 8.1 0.86 a c • • • • 7.7 0.82 8.5 0.89 boys c i • • • • • • • • c co • • • • • • • • c oc • • • • • • • • cr 1/2 • • • • • • • • cr 3/4 • • • • • • • • cr c 5.3 0.59 5.9 0.64 • • • • r 1/4 6.3 0.68 6.9 0.75 • • 5.3 0.60 r 1/3 • • • • • • 5.6 0.62 r 1/2 6.9 0.74 7.6 0.80 5.2 0.59 6.2 0.68 r 2/3 7.6 0.80 8.1 0.86 5.8 0.64 6.8 0.74 r 3/4 8.1 0.85 8.7 0.91 6.4 0.70 7.4 0.78 r c 8.6 0.90 9.6 1.01 7.0 0.75 8.0 0.84 a 1/2 • • • • 7.7 0.81 8.5 0.90 a c • • • • 8.1 0.85 9.3 0.98 1codes: cusp (c), crown (cr), root (r), apex (a). stages: initiation (i), coalescence (co), cusp outline complete (co), complete (c), interradicular root cleft (cl). been collected at harvard university by harold c. stuart (e.g., stuart et al., 1939). world war ii interrupted stuart’s collecting, so data also were obtained from the fels longitudinal study in yellow springs, ohio (roche, 1992). the resulting set of data is somewhat confounded because information on younger and older children were obtained from different populations of “north american white children,” and the fels children had a faster tempo of growth (s. m. garn, pers. comm.). both the harvard and fels data were collected in a longitudinal manner (moorrees, 1959; roche, 1992), which makes it curious that mfh used a graphical method of probit analysis (e.g., finney, 1971) to calculate average ages at attainment of each tooth’s stage of formation. this wastes the value of the longitudinal data because the onset of a stage can be identified directly from successive films, and it treats the data cross-sectionally if the ages of all children exhibiting a stage are averaged (smith, 1991) besides the foldout graphs published in the journal of dental research (mfh, 1963), these authors made copies available to the interested public in an oversize 11” x 17” format. it was intended that a sheet be used once for a child then filed or discarded. we have used these oversize sheets to “reverse engineer” the process of obtaining numerical values from the graphs. positions of the means and lengths of the error bars were obtained with drafting instruments and sliding calipers. some researchers have estimated the means (but not the sd) from the mfh graphs (see, e.g., ubelaker, 1999; smith, 1991; scheuer and black, 2000), but inconsistencies in their data suggest that they used the smaller graphs in the journal of dental research. we were able to base the data in our tables on more precise measurements. moorrees-fanning-hunt standards 16 17 fig. 1. diagrammatic illustrations of the morphological grading system for crown-root mineralization of the singlerooted (top) and multi-rooted teeth (bottom). (modified from moorrees et al., 1963). results means and standard deviations by tooth, grade, and sex are listed in tables 1 and 2. the sample sizes of scorable teeth at each examination were not reported, but they could not have exceeded the 99 boston children available up to about age 10 (48 boys; 51 girls) nor the 246 fels children at later ages (136 boys; 110 girls). according to their text, mfh scored the stages of crown-root formation using a 13-stage (single rooted teeth) or a 14-stage (multi-rooted teeth) scheme. these stages are illustrated in figure 1 and defined in table 3. the difference is simply that the initial mineralization of the interradicular (bifurcation) area is an additional stage for molars. the ordinal scale used by mfh was effectively the brain child of izaac gleiser and edward hunt (1955), also at the forsyth dental infirmary, who previously had created a 15-grade scale to characterize development of the lower first molar. elizabeth fanning (1958, 1960, 1961) elaborated this grading scheme to 20 stages for the molars (and 12 for incisors and 18 for premolars). these schemes, except for the incisors, proved to be too fine-grained, leading to confusion between nearly-identical adjacent grades, so mfh settled on a simpler system. the practical value of the resulting morphological criteria is reflected in its adoption in numerous subsequent studies (e.g., haavikko, 1974; demirjian et al., 1973; anderson et al., 1976; harris and mckee, 1990). fanning actually scored the radiographs in the mfh study using more grades than illustrated in their article (see fig. 1). this is obvious from the inclusion of “extra” grades in their diagrams (and see table 1). for example, r 1/3 and r 2/3 are graphed for some teeth but not others and not included in the grades illustrated in their article. there also is the grade of cr 2/3 that is graphed only for the upper lateral incisor and only for girls, not boys. it seems to us that these “extra” grades were included when there was an adequate sample for statistical analysis, while the illustrations of the grades were made uniform across all tooth types for consistency. discussion how is dental age figured for a child? the mfh approach—which still is broadly applied—uses their graphs to determine the normative chronological ages at which the formative stage of each scorable tooth has been achieved, then these tooth-specific ages are averaged as the person’s dental age. as an example, if the archeological remains of a girl are examined and ui1 and uc both have their root half-formed and the crown of um2 is three-fourths complete, then the normative tooth specific dental ages are 6.6, 7.1, and 6.2 years, respectively (tables 1-2). the average dental age would be the arithmetic mean, 6.6 years. the downside of this method is that the tempos of tooth formation are statistically interrelated (moorrees and kent, 1981; anderson and popovich, 1981), so there is some unknown redundancy in combining all teeth. this remains an ambiguous issue because the structure of tooth interrelationships has not been described in any detail, but it is evident that it varies among individuals and among populations (e.g., tompkins, 1996). some researchers have developed methods of dental aging based on fewer teeth (haavikko, 1974; bolanos et al., 2000), but these simplifications were driven by empirical assessments and on the ease of grading tooth stages—not on statistical criteria. demirjian and coworkers (1973, 1976) dealt with the issue of statistical interrelationships of formative rate among teeth by generating multiple linear regression equations that weighted each tooth’s informational content. they also restricted the number of teeth since, again, intercorrelations are counter to the intuitive moorrees-fanning-hunt standards mandibular molars incisors and premolars 1 4r r 3 4r 1 2 3 4cr 1 2cr c occcoc i ccr cr a 1 2 acri 1 2 3 4 5 6 7 8 9 10 11 12 13 1 4r r 3 4r 1 2 3 4cr 1 2cr c occcoc i ccr cr a 1 2 acri icl 1 2 3 4 5 6 7 8 9 10 11 12 13 14 18 19 approach that more teeth should yield more information about a person’s biological age. we are unaware of any study that has made use of the standard deviations in the mfh article, presumably because there is no way of applying these measures of variation in their graphical form unless the chronological age is known—which often is not the case in archeological, forensic and some ethnological settings (e.g, voors and metselaar, 1958; voors, 1973). now that these values are tabled, they can be used to test for statistical significance, for an individual compared to the group or between the mfh sample and another sample. this can be done on a tooth-specific basis (averaging over individuals) or using the individual as the unit of study (averaging over tooth types) as described by harris et al. (1993). in sum, we have reverse-engineered the often-used graphs published by moorrees, fanning and hunt (1963) to provide normative data on american white children for crown-root development of 10 permanent tooth types. the intent is to make these data—means and standard deviations—more usable in terms of statistical applications and computerization of the dental aging method. literature cited anderson dl, popovich f. 1981. association of relatively delayed emergence of mandibular molars with molar reduction and molar position. am j phys anthropol 1981;54:369-376. anderson dl, thompson gw, popovich f. 1976. age of attainment of mineralization stages of the permanent dentition. j forensic sci 21:191-200. bolanos mv, manrique mc, bolanos mj, briones mt. 2000. approaches to chronological age assessment based on dental calcification. forensic sci int 110: 97-106. conroy cc, vannier mw. 1987. dental development table 2. age at attainment of stages of crown-root formation for the permanent mandibular buccal teeth c p1 p2 m1 m2 m3 grade sd sd sd sd sd sd girls c i 0.5 0.12 1.7 0.24 2.9 0.35 0.1 0.05 3.5 0.41 9.6 1.00 c co 0.7 0.15 2.2 0.28 3.5 0.40 0.2 0.09 3.8 0.43 10.1 1.05 c oc 1.2 0.18 2.9 0.35 4.1 0.47 0.7 0.14 4.3 0.49 10.7 1.11 cr 1/2 1.9 0.25 3.5 0.41 4.7 0.53 1.0 0.17 4.8 0.54 11.3 1.17 cr 3/4 2.9 0.35 4.2 0.49 5.3 0.59 1.4 0.20 5.4 0.59 11.7 1.20 cr c 3.9 0.45 5.0 0.56 6.2 0.66 2.2 0.28 6.2 0.68 12.3 1.27 r i 4.7 0.52 5.7 0.63 6.7 0.73 2.6 0.32 7.0 0.75 12.9 1.32 r cl • • • • • 3.5 0.41 7.8 0.83 13.5 1.39 r 1/4 5.3 0.57 6.5 0.69 7.5 0.79 4.6 0.52 9.1 0.96 14.9 1.53 r 1/2 7.1 0.75 8.1 0.86 8.7 0.92 5.1 0.57 9.8 1.01 15.8 1.62 r 3/4 8.3 0.88 8.8 0.97 10.0 1.05 5.5 0.60 10.5 1.09 16.4 1.67 r c 8.8 0.93 9.9 1.03 10.6 1.12 5.9 0.63 11.0 1.13 17.0 1.71 a 1/2 9.9 1.03 11.0 1.15 12.0 1.24 6.5 0.71 12.0 1.23 18.0 1.82 a c 11.3 1.18 12.1 1.26 13.6 1.40 8.0 0.85 13.8 1.43 20.1 2.01 boys c i 0.5 0.11 1.8 0.24 3.0 0.37 0.0 0.09 3.7 0.42 9.2 0.98 c co 0.8 0.15 2.3 0.31 3.5 0.42 0.2 0.11 4.0 0.44 9.7 1.01 c oc 1.2 0.19 2.9 0.36 4.2 0.48 0.5 0.11 4.8 0.52 10.3 1.07 cr 1/2 2.1 0.27 3.6 0.43 4.7 0.53 1.0 0.17 5.1 0.56 10.9 1.14 cr 3/4 2.9 0.35 4.4 0.52 5.3 0.59 1.5 0.21 5.7 0.61 11.6 1.20 cr c 4.0 0.46 5.2 0.58 6.2 0.69 2.1 0.29 6.5 0.69 12.0 1.24 r i 4.8 0.55 5.8 0.64 6.9 0.74 2.7 0.34 7.1 0.76 12.7 1.32 r cl • • • • • • 3.5 0.41 8.1 0.84 13.6 1.41 r 1/4 5.7 0.63 6.8 0.74 7.8 0.83 4.7 0.53 9.3 0.98 14.6 1.50 r 1/2 8.0 0.86 8.5 0.91 9.4 0.99 5.1 0.57 10.1 1.04 15.1 1.54 r 3/4 9.6 1.00 9.9 1.04 10.8 1.13 5.4 0.61 10.8 1.12 15.9 1.62 r c 10.2 1.06 10.3 1.09 11.5 1.21 5.8 0.64 11.3 1.16 16.3 1.67 a 1/2 11.8 1.23 11.9 1.24 12.7 1.30 6.9 0.75 12.2 1.25 17.6 1.79 a c 13.0 1.35 13.3 1.38 14.2 1.46 8.5 0.91 14.2 1.46 19.2 1.95 moorrees-fanning-hunt standards 18 19 of the taung skull from computerized tomography. nature 329:625-627. crossner cg, mansfield l. 1983. determination of dental age in adopted non-european children. swed dent j 7:1-10. demirjian a, goldstein h, tanner jm. 1973. a new system of dental age assessment. hum biol 45:211227. demirjian a, goldstein h. 1976. new systems for dental maturity based on seven and four teeth. ann hum biol 3:411-421. fanning ea. 1958. a longitudinal study of tooth formation and root resorption. d.d.s. thesis, university of new zealand, 1960. fanning ea. 1960. a longitudinal study of tooth formation and root resorption. d.d.s. thesis, university of new zealand. fanning ea. 1961. a longitudinal study of tooth formation and root resorption. nz dent j 57:202217. fanning ea, moorrees cf. 1969. a comparison of permanent mandibular molar formation in australian aborigines and caucasoids. arch oral biol 14:999-1006. finney dj. 1971. probit analysis, 3rd ed. new york: cambridge university press. garn sm. 1992. personal communication. garn sm, lewis ab, blizzard rm. 1965. endocrine factors in dental development. j dent res 44:243258. gleiser i, hunt jr ee. 1955 the permanent mandibular first molar: its calcification, eruption and decay. am j phys anthropol 13:253-281. haavikko k. 1970. the formation and the alveolar and clinical eruption of the permanent teeth: an orthopantomographic study. proc finn dent soc 66: 103-170. haavikko k. 1974. tooth formation age estimated on a few selected teeth: a simple method for clinical use. proc finn dent soc 70:15-19. table 3. definitions of the tooth formation stages 1 single multi rooted rooted teeth definitions teeth 1 initial cusp formation: amelogenesis has begun on the individual cusp tips. 1 2 coalescence of cusps: centers of mineralization are merged but 2 the border is not everywhere radiodense 3 cusp outline complete: the coronal outline of the tooth is mineralized. 3 4 crown 1/2 formed: amelogenesis has proceeded half way to the 4 crown-root as judged from morphology of the radiodense portion 5 crown 1/2 complete 5 6 crown complete: morphologically, all the crown has mineralized 6 but root formation has not begun. 7 initial root formation: there is a trace of root radiopacity below the crown outline. 7 -initial cleft formation: mineralization is evident in the interradicular area. 8 8 root length 1/4: the radiographic morphology of the root 9 is 1/4 its projected final size. 9 root length 1/2 complete. 10 10 root length 3/4 complete. 11 11 root length complete. 12 12 apex half closed: the lateral borders of the root tip become convex 13 rather than tapered as earlier. 13 apical closure complete: size of the apical foramen is reduced 14 to its mature size. 1 modified from harris and mckee (1990). moorrees-fanning-hunt standards 20 21 harris ef. 2002. dental development and anomalies in craniosynostosis and facial clefting. in: mooney mp, siegel mi, editors understanding craniofacial anomalies: the etiopathogenesis of craniosynostosis and facial clefting. new york: john wiley-liss, p 425-467. harris ef, barcroft bd, haydar s, haydar b. 1993. delayed tooth formation in low birthweight american black children. pediatr dent 15:30-35. harris ef, mckee jh. 1990. tooth mineralization standards for blacks and whites from the middle southern united states. j forensic sci 35;859-872. keller ee, sather ah, hayles ab. 1970. dental and skeletal development in various endocrine and metabolic disease. j am dent assoc 81:415-419. kent rl jr, reed rb, moorrees cf. 1978. associations in emergence age among permanent teeth. am j phys anthropol 48:131-142. liversidge hm. 2000. crown formation times of human permanent anterior teeth. arch oral biol 45:713-721. liversidge hm, molleson ti. 1999. developing permanent tooth length as an estimate of age. j forensic sci 44:917-920. marshall wa, tanner jm. 1969. variations in pattern of pubertal changes in girls. arch dis child 44:291-303. marshall wa, tanner jm. 1970. variations in pattern of pubertal changes in boys. arch dis child 45:13-23. merwin dr, harris ef. 1998. sibling similarities in the tempo of tooth mineralization. arch oral biol 43: 205-210. moorrees cfa. 1959. the dentition of the growing child. cambridge: harvard university press. moorrees cfa, fanning ea, hunt jr ee. 1963. age variation of formation stages in ten permanent teeth. j dent res 42:1490-1502. moorrees cfa, kent jr rl. 1981. interrelations in the timing of root formation and tooth emergence. proc finn dent soc 77:113-117. nadler gl. 1998. earlier dental maturation: fact or fiction. angle orthod 68:535-538. owsley dw, jantz rl. 1983. formation of the permanent dentition in arikara indians: timing differences that affect dental age assessments. am j phys anthropol 61:467-471. pelsmaekers b, loos r, carels c, derom c, vlietinck r. 1997. the genetic contribution to dental maturation. j dent res 76:1337-1340. roche af. 1992. growth, maturation, and body composition: the fels longitudinal study 1929-1991. cambridge: cambridge university press. scheuer l, black s. 2000. developmental juvenile osteology. san diego: academic press. smith bh. 1991. standards of human tooth formation and dental age assessment. in: kelley ma, larsen sp, editors. advances in dental anthropology. new york: wiley-liss, p 143-168. stuart hc. 1939. studies fromthe center for research in child health and development, school of public health, harvard university. i. the center, the group under observation, sources of information, and studies in progress. monogr soc for research child devel, series no. 20, p 1-261. tanner jm, whitehouse rh, marshall wa, healy mjr, goldstein h. 1975. assessment of skeletal maturity and prediction of adult height: tw2 method. london: academic press. tompkins rl. 1996. human population variability in relative dental development. am j phys anthropol 99:79-102. ubelaker dh. 1999. human skeletal remains: excavation, analysis, interpretation, 3rd ed. washington: taraxacum. voors aw. 1973. can dental development be used for assessing age in underdeveloped communities? j trop pediatr environ child health 19:242. voors aw, metselaar d. 1958. the reliability of dental age as a yardstick to assess the unknown calendar age. trop geogr med 10:175-180. moorrees-fanning-hunt standards decoding your subscription want to know when your subscription to dental anthropology expires? membership in the association and, thus, your subscription to dental anthropology is on an annual basis coinciding with the calendar year. have a look at the mailing label on the evelope that this issue arrived in, and you will see the year for which your dues have been paid. the year is located in parentheses to the right of your name. so, if the mailing label says “(2002)” you are paid to the end of this calendar year. in order to extend your membership, fill-out the relevant portions of the enclosed form—remember to include appropriate payment—and mail it to the secretary-treasurer of the association: dr. diane hawkey department of anthropology arizona state university tempe, arizona 85287-2402 usa e-mail: hawkey@asu.edu lukacs 1995.1 page 02.jpg page 03.jpg page 04.jpg page 05.jpg brook and scheers 2006.1 33 *correspondence to: a. h. brook, school of dental studies, edwards building, university of liverpool, pembroke place, liverpool l69 3gn, uk email: a.h.brook@liverpool.ac.uk tooth root morphology can provide valuable additional evidence to crown morphology in studies of prehistoric, historic and modern populations. the determination of root morphology may be multifactorial, as is crown morphology, with both genetic and environmental factors involved (winter and brook, 1989). variations of root morphology include the number of roots, as with accessory roots or fused roots, their shape, as in taurodontism, or their size. ethnic differences in root morphology have been recognized (dixon and stewart, 1976). the present study aimed to derive data for root anomalies in a homogeneous romano-british population and to investigate associations with other dental anomalies in this group. also the study aimed to develop further the methodology of measurement and the reproducibility of diagnosis of root anomalies in archeological material, enhancing comparisons with other ancient and modern populations. materials and methods the skulls investigated were from a cemetery of the roman town of durnovaria, close to the site of the modern poundbury, dorset, uk. the cemetery dates from the 3rd to 5th century ad and is of a christian character. the population was of native british origin throughout this period (farwell and molleson, 1993). variations of tooth root morphology in a romanobritish population alan h. brook* and marlene scheers school of dental studies, university of liverpool, united kingdom abstract: tooth morphology can provide valuable evidence in studies of prehistoric, historic and modern populations. the aims of this study were to derive data for root anomalies in a romano-british population, to investigate associations between anomalies, and to compare findings with other populations to provide evidence concerning etiology. an additional aim was to develop further the methodology and reproducibility in such studies. from the christian cemetery of 3rd-5th century ad in poundbury, uk, 385 skulls were suitable for examination. radiographic technique was standardized with custom-made skull supports and criteria established for each anomaly. there was a high level of reproducibility for the diagnosis of each anomaly. the prevalence of the anomalies in individuals was: three-rooted mandibular first molars 1.8%, fused roots 14.0%, cuneiform roots 16.9%, taurodontism 26.9%, and invaginated teeth 1.1%. there were highly significant (p < 0.001) associations between fused and cuneiform roots, and both were significantly associated with third molar hypodontia (p < 0.002; p < 0.05). these reductions in root morphology were commonly bilateral and more frequent in females, as is hypodontia. the findings of this study are compatible with a multifactorial etiology of these anomalies, showing continuous variation in root morphology. the gradients of anomalies observed are also compatible with the concept of morphogenetic fields. dental anthropology 2006;19(2):33-38. the excavated skulls are housed at the british museum (natural history), london, uk. the total collection from this burial site consists of 1,100 crania, but a large proportion of these are very fragmented and unsuitable for this study. the criterion for inclusion in the present investigation was a jaw that had at least one permanent molar and one permanent incisor present. juvenile skulls with a dental age of less than 9 years were excluded. the resultant sample was 385 skulls suitable for examination of root morphology. age and sex determinations were made by the staff of the british museum based on the long bones, pelvic girdles and skulls. of the sample, 40.0% (154) were estimated male, 38.7% (149) female, and for 21.3% (82) no determination could be made. radiographs were taken of all teeth using an industrial apparatus and kodak ultraspeed dental occlusal films. a pilot study established the optimum voltage, current and exposure time as well as the standardized positioning of the x-ray tube, skull and films. customized wooden blocks were developed for positioning the skulls. a total of 6 films per skull 34 a.h. brook and m. scheers provided full coverage of the teeth (fig. 1). to calibrate measurements, all films were taken including a 20 mm length of orthodontic wire. the films were developed and viewed under standardized conditions. the anomalies diagnosed were three-rooted mandibular first permanent molars, fused (pyramidal) and cuneiform roots, taurodontism and crown and root invaginations. the radiographic criteria for the five anomalies diagnosed in the study were: (1) three-rooted mandibular first molar: evidence of a third root; (2) fused molar root: a pyramidal root form with no evidence of an interradicular bony septum or periodontal ligament but with separation of root canals; (3) cuneiform molar root: a root form with a central root canal whose shape followed the root outline; (4) taurodontism: criteria of holt and brook (1979; fig. 2); and (5) crown invaginations: criteria of hallett (1953); types 2, 3 and 4 were scored following grahnen et al. (1959) and brook (1974). for each anomaly, prevalence for skulls, prevalence for teeth, sex distribution, and symmetry were investigated. to test the reproducibility of the diagnosis, the radiographs of 20% of the sample were read on a second, separate occasion. the reproducibility findings are in table 1. results the findings for the prevalence for skulls and sex distribution of the root anomalies studied are shown in table 2, which also indicates the number of individuals suitable for scoring each anomaly. three-rooted mandibular first molars—those with an accessory root—had a prevalence of 1.8% of skulls and a tooth prevalence of 1.5%. in half of the individuals the anomaly was bilateral and equal numbers of males and females were affected. for reduction in root number the prevalence for fused roots was 14.0% of skulls and for cuneiform roots was 16.9% of skulls. the tooth prevalence for reduced root number was 2.7% for fused roots and 3.4% for cuneiform roots, some individuals possessing both anomalies. maxillary molars were affected more frequently than mandibular molars. third molars were more often affected than second molars, with no example being found in first permanent molars. the male to female ratios of 1:2.2 for fused roots and 1:2 for cuneiform roots were statistically significant (p < 0.02 and p < 0.01, respectively). in 30% of affected skulls these anomalies were bilateral, and occasionally a fused root was seen on one side of the dental arch with a cuneiform root on the contralateral tooth. taurodontism was found in 26.9% of skulls, with a tooth prevalence in lower molars of 11.7%. third molars were the teeth most often affected and first molars the least. taurodontism was bilateral in 47% of affected skulls. the male to female ratio was 1:0.67 and statistically significant (p < 0.05). the differences between mean values of a and of a:b ratios (fig. 2) in those teeth showing taurodontism compared to fig. 1. full coverage of the dentition using six radiographs. baseline = axis between mesial and distal points of amelo-cemental junction. a = distance from baseline to highest point on pulp chamber floor. b = distance from baseline to apex of distal root. fig. 2. measurement used for taurodontism (after holt and brook, 1979). 35tooth root morphology in romano-britons those without were highly significant (p < 0.001). for measurement b, the differences were statistically significant for second molars (p < 0.01) and third molars (p < 0.001). the prevalence of invaginated teeth was 1.1% of skulls. all invaginations in this sample occurred in maxillary lateral incisors. there was no evidence of periapical bone loss in relation to the crown invaginations that were all of the mild hallett (1953) class 2 category. no example of root invaginations was seen in this study. the statistically significant associations between anomalies in this study were between fused and cuneiform molar roots (p < 0.001) and between taurodontism and fused molar roots (p < 0.05). using results from a study of anomalies of tooth number and size in this population (brook and john, 1995) statistically significant associations were found between congenital absence of third molars and fused molar roots (p < 0.02), cuneiform molar roots (p < 0.05), and taurodont lower molars (p < 0.001). discussion the high level of reproducibility of measurements and diagnosis suggests that the present data are reliable within the constraints of the sample (table 1). comparisons with other historic and modern sample findings are therefore worthwhile. in other studies of three-rooted mandibular first molars either radiographs (souza-freitus et al., 1971) or extracted teeth (curzon, 1973) have been used. the radiographs in the present study were of good quality (fig. 1) having been carefully standardized in the pilot study. for caucasians the findings for three-rooted mandibular first molars have usually been of the order of 1% of individuals affected, while the frequency in mongoloid peoples is much higher (scott and alexandersen, 1992). the romano-british figure of 1.8% conforms to modern caucasian results reviewed by alexandersen (1963). the criterion used for the diagnosis of cuneiform roots is shown by holt (1976) to be highly reproducible, especially in lower molars. in this study, the one reversal of diagnosis (table 1) was a maxillary molar that on the second occasion was diagnosed as having a fused root. the criterion for fused molar roots was adapted from brabant and kovacs (1961) and provided an acceptable degree of consistency (table 1). similar to brabant and kovacs (1961), the highest frequency of cuneiform roots was found in maxillary third molars. for mandibular second molars the romano-british prevalence was 3.2% of skulls, comparable to the findings of pedersen (1949) in eastgreenland skull material and of holt (1976) based on brook’s (1974) large population sample of modern british caucasian schoolchildren. reduction in root number affecting first permanent molars would seem to be rare as no example was found in these romanobritish skulls or by pedersen (1949), holt (1976) or molnar and horvath (1995). the tendency for a bilateral occurrence of anomalies of reduced root number is found in other studies also, with the same trend for fused and cuneiform roots to occur in antimeric teeth where each anomaly was not bilaterally symmetrical (holt, 1976; ross and evanchik, 1982; tamse and kaffe, 1981; molnar and horvath, no. diagnosed on no. diagnosed on no. diagnosed on feature first occasion second occasion on both occasions three-rooted mandibular first molars 1 1 1 fused molar roots 11 13 11 cuneiform molar roots 16 15 15 invaginations 2 1 | 1 2 1 1 1 b. using ratios no. of teeth no. within 0.5 of feature measured ratio on first reading taurodont mandibular molars 272 212 table 1. reproducibility of measurements and diagnosis a. clinical diagnosis 36 a.h. brook and m. scheers n o. o f n o. o f n o. o f af fe ct ed af fe ct ed u n kn ow n se x ra ti o to ta l a n om al y m al es p re v al en ce fe m al es p re v al en ce se x p re v al en ce m al e: fe m al e ca se s p re v al en ce t h re ero ot ed m an d ib u la r fi rs t m ol ar 3 2. 3% 3 2. 4% 0 0% 1: 1 6 1. 8% (n = 13 2) (n = 12 7) (n = 71 ) (n = 33 0) fu se d r oo t (u p p er an d lo w er m ol ar t ee th ) 13 8. 5% 29 19 .5 % 12 14 .6 % 1: 2. 2 54 14 .0 % (n = 15 3) (n = 14 9) (n = 82 ) (n = 38 4) c u n ei fo rm r oo t (u p p er an d lo w er m ol ar t ee th ) 19 12 .4 % 38 25 .5 % 10 12 .2 % 1: 2 65 16 .9 % (n = 15 3) (n = 14 9) (n = 82 ) (n = 38 4) ta u ro d on ti sm (l ow er m ol ar s) 48 34 .8 % 31 22 .3 % 15 20 .5 % 1: 0. 67 94 26 .9 % (n = 13 8) (n = 13 9) (n = 73 ) (n = 35 0) r oo t in v ag in at io n 2 | 2 0 0. 0% 0 0. 0% 0 0. 0% 0 0 0. 0% (n = 11 1) (n = 10 3) (n = 65 ) (n = 27 9) c ro w n in v ag in at io n 2 | 2 2 1. 8% 1 1. 0% 0 0% 1: 0. 5 3 1. 1% (n = 11 1) (n = 10 3) (n = 65 ) (n = 27 9) t a b l e 2 . p re va le n ce s in s ku ll s an d se x di st ri bu ti on s of r oo t an om al ie s 37 1995). there is also agreement that these anomalies are more common in females than males (brabant and kovacs, 1961; holt, 1976; ross and evanchik, 1981; table 1). for taurodontism, comparisons are limited by the use of different criteria in different studies. using the same methodology as the present study, holt and brook (1979) found that 6.3% of 1,115 modern british caucasian schoolchildren had a taurodont mandibular first permanent molar compared to 1.8% of the romano-british skulls. the prevalence and degree of taurodontism is often greater in second and third molars (molnar and horvath, 1995); in the present romano-british sample the prevalence was 26.9% of skulls. shifmann and chanannel (1978) report that taurodontism occurred bilaterally in most cases while in this study and in holt and brook (1979) approximately equal numbers of tooth pairs were affected bilaterally and unilaterally. the sex ratio in this study of male 1: female 0.67 is similar to that of holt and brook (1979). the prevalence of invaginated teeth in these romano-britons at 1.6% is lower than that for modern british, 4.1% (brook, 1974) and modern swedish 3.0% (grahnen et al., 1959) samples. building on the comments of previous authors who remarked on a tendency for fused and cuneiform molar roots to be found together, this study provides evidence of the highly statistically significant association between these two anomalies. similarly, the association of root number reduction of molars with congenital absence of third molars noted by keene (1966) was found to be statistically significant in these romano-britons. stoy (1960), stenvik et al. (1972) and holt and brook (1979) describe the association of taurodontism and hypodontia. in this study the association between taurodontism and hypodontia of third molars was shown to be highly significant statistically. this finding is compatible with a morphogenetic field effect with a varying influence anteroposteriorly. the strong association between fused and cuneiform molar roots could indicate that the cuneiform root is one extreme of a continuous variation showing different degrees of confluence of roots and their canals. complete root separation would represent the opposite extreme. in conclusion, for root anomalies in this romanobritish population, the prevalence for skulls and for teeth, the sex distribution and bilateral symmetry has been established. the radiographic technique developed and the criteria used have high degrees of reproducibility. the statistically significant associations demonstrated in the romano-britons showed the relationship between fused roots and cuneiform roots as reductions in root number and shape and also their relationship with congenital absence of teeth. the gradients of anomalies observed were compatible with the concept of morphogenetic fields. the findings were also compatible with multifactorial etiology, showing continuous variation in root size and shape. literature cited alexandersen v. 1963.double-rooted human lower canine teeth. in: brothwell dr, editor. dental anthropology. new york: pergamon press, p 235244. brabant h, kovacs i. 1961. a contribution to the study of taurodontism in modern races and of its possible relation to the pyramidal roots of molars. bull group rech scient stomot 4:232-286. brook ah. 1974. dental anomalies of number, form and size: their prevalence in british schoolchildren. j int assoc dent child 5:37-53. brook ah, john cc. 1995. dental anomalies of number and size in a romano-british population. in: radlanski rj, renz h, editors. proceedings of 10th international symposium on dental morphology. berlin: c and m brunne gbr, p 177-180. curzon mej. 1973. three-rooted mandibular permanent molars in english caucasians. j dent res 52:181. dixon gh, stewart re. 1976. general aspects of anomalous tooth development. in: stewart r e and prescott g h, editors. oral facial genetics. st louis: c v mosby, p 133-135. grahnen h, lindahl b, omnell ka. 1959. dens invaginatus: i. a clinical roentgenological and genetical study of permanent upper lateral incisors. odont revy 10:115-137. hallett gem. 1953. the incidence, nature and clinical significance of palatal invaginations in the maxillary incisor teeth. proc r soc med 46:491-499. holt rd. 1976. the prevalence of root anomalies in children. msc thesis, university of london. holt rd, brook ah. 1979. taurodontism: a criterion for diagnosis and its prevalence in mandibular first permanent molars in a sample of 1,115 british schoolchildren. j int assoc dent child 10:41-47. keene hj. 1966. a morphological and biometric study of taurodontism in a contemporary population. am j phys anthropol 25:208-209. molnar e, horvath g. 1995. developmental anomalies of the teeth in historic skeletal samples. in: radlanski rj, renz h, editors. proceedings of the 10th international symposium on dental morphology. berlin: c and m brunne gbr, p 377-385. oehlers fa. 1958. the radicular type of dens invaginatus. oral surg oral med oral pathol 11:251-260. pedersen po. 1949. the east greenland eskimo dentition: numerical variations and anatomy. copenhagen: c a retzels forlag. ross if, evanchik pa. 1981. root fusion in molars: incidence and sex linkage. j periodontol 52:663667. scott gr, alexandersen v. 1992. dental morphological variation among medieval greenlanders, tooth root morphology in romano-britons 38 icelanders and norwegians. in: smith p, tchernov e, editors. structure, function and evolution of teeth. london: freund publishing house, p 467-490. shifmann a, chanannel i. 1978. prevalence of taurodontism found in a radiographic dental examination of 1,200 young adult israeli patients. community dent oral epidemiol 6:200-203. souza-freitus j a, lopez e s, casati-alvares l. 1971. anatomic variations of lower first permanent molar roots in two ethnic groups. oral surg oral med oral pathol 31:274-278. stenvik a, zachrisson bu, svatun b. 1972. taurodontism and concomitant hypodontia in siblings. oral surg oral med oral pathol 33:841-845. stoy pj. 1960. taurodontism associated with other dental anomalies. dent pract dent rec 10:202-205. tamse a, kaffe i. 1981. radiographic survey of the prevalence of conical lower second molar. int endod j 14:188-190. winter gb, brook ah. 1989. tooth abnormalities. in: rowe hr, alexander ag, johns rb, editors. a comprehensive guide to clinical dentistry. london: class publishing, p 55-103. a.h. brook and m. scheers rodriguez-florez and colantonio 2007.4 19 bilateral symmetry is the antimeric repetition of the size and shape of a structure. in a morphological sense, symmetry can be defined as if the structure were divided into two or more parts exactly identical in size, shape, and position relative to the dividing point; in other words, the repetition is of exactly similar parts facing each other across the body’s midline. van valen (1962) grouped deviations from perfect symmetry in the structures of an organism into three types, namely (1) directional asymmetry (such as position of the mammalian heart); (2) antisymmetry (such as rightand left-handedness); and (3) fluctuating asymmetry (an asymmetry involving a paired structure that is usually distributed symmetrically). fluctuating, mirror or flip symmetry may be either qualitative or quantitative. bilateral asymmetry in tooth cusp occurrence (the presence or absence of a cusp on a tooth) is an example of qualitative fluctuating asymmetry (staley and green, 1971). theoretically, antimeric teeth should exhibit symmetrical mirror images of each other with respect both to size and surface detail (scott, 1977). some studies suggest that mirror imaging of asymmetry in twins likely results from chance effects of minor developmental disturbances between bilateral structures (wetherell et al., 1994). increased directional asymmetry has been reported in the occlusal morphology of first permanent molars from 45,x/46,xx mosaics, indicating that the different cell lines (each regulated by different genes) may be responsible for the more pronounced differences bilateral asymmetry of upper permanent dentition in six archeological pre-conquest samples from colombia, south america carlos david rodríguez-flórez1* and sonia e. colantonio2 1grupo de investigaciones arqueodiversidad, museo arqueológico “julio césar cubillos,” universidad del valle colombia 2cátedra de antropología biológica y cultural, facultad de ciencias exactas, físicas y naturales, universidad nacional de córdoba conicet argentina *correspondence to: carlos david rodríguez-flórez, grupo de investigaciones arqueodiversidad, museo arqueológico “julio césar cubillos,” universidad del valle colombia e-mail: david@syllabapress.com abstract bilateral asymmetry is an important field of study in physical anthropology. the present study evaluated the frequencies of bilateral asymmetry of four traits (one for each tooth type in the maxillary arcade) in six pre-conquest human archeological samples from colombia, south america. results show the importance of a preliminary analysis of bilateral asymmetry in archeological fragmented samples and its relevance in molding subsequent interpretations. dental anthropology 2007;20:19-23. observed on left than right molars (piriniemi et al., 1998). observations on the expressions of bilateral asymmetry in human dental morphological traits has been used in dental anthropology in a manner similar to a measure of population heritability (garn et al., 1966a; staley and green, 1971; baume and crawford, 1979). little metrical differences between antimeric teeth have been reported (garn et al., 1966b; garn and bailey, 1977). bailit et al. (1970) discuss their observations that metric fluctuating asymmetry values of tooth crown dimensions vary among human populations. in a study concerning the invariable bilateralism of carabelli´s trait (i.e., the suggestion that this trait always occurs bilaterally when present), meredith and hixon (1954) reported that, in fact, nearly 13% of their sample exhibited expression of the trait on just one side of the dental arch. small side differences in trait expressions were reported by wood and green (1969) who compared the bilateralism of seven morphological traits in premolars of twins. similar deductions for carabelli’s trait were reached by scott (1972, cited in scott, 1977) and by biggerstaff (1973). another factor that can be important in evaluating 20 the extent of bilateral asymmetry in a sample is sample size. garn et al. (1979) showed how the effect of small samples (generally below 100 and in some cases as small as 15) increases the apparent intergroup differences in tooth crown asymmetry and, thus, how small sample sizes can influence biological interpretations. dental asymmetry in fragmented archeological samples the use of morphological traits from the human dentition can create some problems of a methodological nature when studying fragmented archeological samples. one issue is the assumption of dental trait expression as individually immutable, in the sense of being morphologically symmetrical between homologous teeth. in bioarcheology, estimating the frequency of a dental trait is influenced by the availability of samples and limited crown wear and the absence of caries (so the presence of the trait can be ascertained). some authors recommend scoring the higher grade of expression for each dental trait (turner and scott, 1977) or counting both the left and right sides for each individual (haeussler et al., 1988). in cases where the bioarcheologist only has fragmented remains (pieces from maxillas and mandibles) these counting methods are very practical. either of these two recording methods maximizes the usable sample sizes without taking into account unilateral or bilateral trait expression. but, if we consider this affirmation in detail, an anthropological study on archeological samples could be carried out without a previous evaluation of bilateral asymmetry, thus underestimating possible environmental influences on trait expressions as much as over-estimating its taxonomic value and relevance in microevolutionary and historical inferences. at this point, researchers face a recording problem with only two possible alternatives: counting the trait as bilateral or discarding the individual, thus reducing the total sample size. there seem to be very few prior bioarcheological studies that deal with this issue of bilateral asymmetry as it relates to the development of biological distance calculations. taking into account that bilateral asymmetry could reflect environmental influences, and that bilateral trait asymmetries could affect a trait’s usefulness in determining biological distances, we undertook a study of bilateral asymmetry on dental types. prior to using fragmented arches and traditional counting procedures for trait presence (turner and scott, 1977; haeussler et al., 1988), bilateral analysis of available complete dental arches from the same sample can add elements that help develop useful comparative indicators in the crowns. the present study was carried out using six human pre-conquest samples from colombia, with the aim of exploring the ranges of morphologic reliability of each dental type. materials and methods this study consists of data from six pre-conquest human populations from colombia dated between the viii and xv centuries a.d. (table 1). the sample sizes (n) correspond to the total number of individuals with complete arches that could be examined. permanent teeth of 58 individuals between 10 and 20 years of age with complete arches (maxilla) were selected (fig. 1). the dental traits examined here are listed in table 2. the asu dental anthropology system was used to register the expression grade of incisor shovel shape, distal accessory ridge, and carabelli’s complex. the marginal ridges on the maxillary premolars were observed following the descriptions of burnett (1996). a binary recording system was employed that consisted of grouping all trait expressions into either “present” (1) and “absent” (0) categories. then, using these records, molto´s bilateral index (bi) was calculated with this formula: bi = (bp / bp + up) x 100 where bi is the bilateral index, bp is the count of cases (individuals) where the trait is present bilaterally, and up is the count of cases where the trait is present just unilaterally. the bilateral index quantifies the tendency for a trait to occur symmetrically. an index above 50 suggests a positive bilateral tendency for the trait (tocheri, 2002). the standard deviation and coefficient of variation also were calculated for the assessments of intraand inter-sample variation of bilateral traits’ presence. table 1. materials used in this study sample centuries (a.d.) collection provenience n obando viii xiii museo arqueológico, univalle valle del cauca 13 guacanda x xv museo arqueológico, univalle valle del cauca 9 la escopeta xiii xv museo arqueológico, univalle valle del cauca 6 el morro tambo xiii xv museo de historia natural, unicauca cauca 7 marín xiii xv museo nacional de colombia cundinamarca 11 soacha x xiii museo nacional de colombia cundinamarca 12 total 58 c.d. rodríguez-flórez et al. 21 results bilateral and unilateral presence of traits and bilateral index values are shown in table 3. bilateral expressions of shovel shape (maxillary central incisor), distal accessory ridge (maxillary canine), and marginal ridges (maxillary first premolar) all show clear tendencies to occur bilaterally—with values higher 50—and relatively low standard deviations (sd) and variation coefficients (cv). in contrast, carabelli´s trait exhibits the highest sd and cv (table 4). comparing among the samples, exceptional values are found in la escopeta, which has a cv higher than 50% (table 5). discussion with the assumed model of polygenetic inheritance, trait expression is due to interactions among a number of genes at different loci that interplay with environmental factors to produce the phenotypic expression of that trait. it is supposed that various genes have different contributions to phenotypic variation but they have an additive effect on the trait in question (lauc et al., 2003). dental asymmetry has generally been thought to be an indicator of developmental instability in humans and other animals. the occurrence of bilateral asymmetry can be interpreted as a reflection of instability in the normal development of a biological form (palmer and strobeck, 2003). results of the present study suggest that the expression of carabelli’s complex (on um1) is most easily influenced by environmental forces from among the several traits examined. bi values for carabelli’s trait were below 50 for guacanda and for la escopeta; both of these pre-conquest samples suggest that this trait would have low taxonomic value, at least in biological comparisons that involve these two samples. cv values for this trait (37.3%) and his variation in the la escopeta sample (50.1%) support this conclusion. the comparatively high frequency of bilateral asymmetry for this dental trait could indicates its greater sensitivity to environmental stressors; comparably, these data may also imply changes in the gene pool of these prehistoric people. other values greater but still close to a bi of 50 occurred in the samples from el morro-tambo (i.e., shovel shape ui1 bi = 66), soacha (i.e., carabelli um1 bi = 60), and guacanda (i.e., marginal ridges up1 bi = 57). the bilateral expression of these traits could also represent an environmental impact that could influence the phenetic component in the total sample. of the traits studied, the distal accessory ridge displays the highest bi values, which promotes its reliability for use in phenetic inter-group comparisons. an appreciation of the degree of bilateral expression of dental features such as carabelli’s trait, shovel shape incisors, and marginal ridges is valuable in order to assess the importance of previous bilateral asymmetry analysis in a prehistoric dental series. estimating the bilateral index is useful for the observation of possible environmental influences that can affect the overall frequency of the trait expression sufficient to exclude carabelli´s trait in biological distances that polled all populations considered here. thanks to the present evaluation, analysis of the samples can be pursued more carefully in the validation of dental traits expressed for um1 prior to phenetic analysis, in this case carabelli’s trait. to conclude, it is advisable to consider a bilateral analysis of fragmented archeological samples prior to the more complete investigation since it provides additional, insightful elements for among-sample interpretation. literature cited bailit hl, workman pl, niswander jd, mcclean cj. 1970. dental asymmetry as an indicator of genetic and environmental conditions in human populations. hum biol 42:626-638. table 2. dichotomization of trait expressions used in this study tooth type trait dichotomy presence absence ui1 shovel shape 0 vs 1 6 1 6 0 uc distal accesory ridge 0 vs 1-5 1 5 0 up1 marginal ridges 0 vs 1 1 0 um1 carabelli’s trait 0 vs 1-6 1 6 0 dental bilateral asymmetry fig. 1. um1 of indiviual 7 from la escopeta. 22 t a b l e 3 . v al u es o bs er ve d in t hi s st u dy 1 sh ov el s h ap e u i1 d is ta l a cc es so ry r id g e u c m ar g in al r id g es u p 1 c ar ab el li u m 1 b p u p b p u p b p u p b p u p sa m p le n k % k % b i n k % k % b i n k % k % b i n k % k % b i o ba n d o 13 10 76 .9 1 7. 7 90 .9 13 10 76 .9 1 7. 7 90 .9 13 8 61 .5 2 15 .4 80 .0 13 5 38 .5 2 15 .4 71 .4 g u ar an d a 9 7 77 .8 2 22 .2 77 .8 9 5 55 .6 2 22 .2 71 .4 9 4 44 .4 3 33 .3 57 .1 9 2 22 .2 2 22 .2 50 .0 l a e sc op et a 6 6 10 0. 0 0 0. 0 10 0. 0 6 5 83 .3 1 16 .7 83 .3 6 6 10 0. 0 0 0. 0 10 0. 0 6 1 16 .7 4 66 .7 20 .0 e l m or ro –t am bo 7 4 57 .1 2 28 .6 66 .7 7 5 71 .4 1 14 .3 83 .3 7 4 57 .1 1 14 .3 80 .0 7 3 42 .9 1 14 .3 75 .0 m ar ín 11 8 80 .0 2 20 .0 80 .0 10 9 90 .0 1 10 .0 90 .0 10 6 60 .0 2 20 .0 75 .0 10 4 40 .0 1 10 .0 80 .0 so ac h a 12 9 75 .0 3 25 .0 75 .0 12 10 83 .3 1 8. 3 90 .9 12 9 75 .0 1 8. 3 90 .0 12 3 25 .0 2 16 .7 60 .0 su m m at io n 57 44 10 57 44 7 57 37 9 57 18 12 m ea n 81 .7 85 .0 80 .4 59 .4 1 b p = b il at er al p re se n ce ; u p = u n il at er al p re se n ce ; b i = b il at er al i n d ex c.d. rodríguez-flórez et al. 2� baume rm, crawford mh. 1979. discrete dental trait asymmetry in mexico and belize. j dent res 58:1811. biggerstaff rh. 1973. heritability of the carabelli cusp in twins. j dent res 52:40-44. burnett se. 1996. a new look at premolar trait variation: maxillary premolar accessory ridges. dental anthropology 10:17-18. garn sm, bailey sm. 1977. the symmetrical nature of bilateral asymmetry of deciduous and permanent teeth. j dent res 56:1422. garn sm, cole pe, smith bh. 1979. the effect of sample size on crown size asymmetry. j dent res 58:2012. garn sm, lewis ab, kerewsky rs. 1966a. bilateral asymmetry and concordance in cusp number and crown morphology of the mandibular first molar. j dent res 45:1820. garn sm, lewis ab, kerewsky rs. 1966b. the meaning of bilateral asymmetry in the permanent dentition. j dent res 36:55-62. haeussler am, turner cg ii, irish jd. 1998. concordance of american and soviet methods in dental anthropology. am j phys anthropol 75:218. lauc t, rudan p, rudan i. campbell h. 2003. effect of inbreeding and endogamy on occlusal traits in human isolates. am j orthod 30:301-308. meredith hv, hixon eh. 1954. frequency. size. and bilateralism of carabelli´s tubercle. j dent res 33:435440. palmer ar, strobeck c. 2003. fluctuating asymmetry analyses revisited. in: polak m, editor. development instability: causes and consequences. oxford: oxford university press, p. 279-319. piriniemi p, alvesalo l, silven o, heikkila j, julku j, karjalahti p. 1998. asymmetry in the occlusal morphology of first permanent molars in 45.x/46. xx mosaics. arch oral biol 43:25-32. scott gr. 1977. classification, sex dimorphism, association. and population variation of the canine distal accesory ridge. hum biol 49:453-469. staley rn, green lj. 1966. bilateral asymmetry in tooth cusp occurrence in human monozygotic twins. dizygotic twins. and nontwins. j dent res 50:83-89. tocheri mw. 2002. the effects of sexual dimorphism, asymmetry, and inter-trait association on the distribution of thirteen deciduous dental nonmetric traits in a sample of pima amerindians. dental anthropology 15:1-8. wetherell j, winning t, townsend gc. 1994. localized asymmetry in human dental crown form – an interesting case. dental anthropology 17:18-23. wood bf, green lj. 1969. second premolar morphologic trait similarities in twins. j dent res 48:74-78. turner cg ii, scott gr. 1977. the dentition of easter islanders. in: dahlberg aa, graber tm, editors. orofacial growth and development. the hague: mouton. p. 229-249. van valen l. 1962. a study of fluctuating asymmetry. evolution 16:125-142. table 4. bi statistics for each dental trait shovel shape distal accesory ridge marginal ridges carabelli sample ui1 uc up1 um1 mean 81.73 84.99 80.36 59.4 sd 11.91 7.544 14.47 22.15 cv (%) 14.57 8.877 18.01 37.29 *sd = standard deviation. cv = coefficient of variation table 5. bi statistics calculated for each pre-conquest sample, all traits considered statistic obando guaranda la escopeta morro-tambo marín soacha mean 83.31 64.09 75.83 76.25 81.25 78.98 sd 9.445 12.75 38.04 7.249 6.292 14.6 cv (%) 11.34 19.9 50.17 9.507 7.743 18.49 dental bilateral asymmetry peck 2004.4 62 63 in the last issue of dental anthropology, edgar and sciulli (2004) highlighted an interesting abnormality of human mandibular premolar (mnp) shape in their report, “elongated mandibular premolar: a new morphological variant.” they noted that the affected premolar is characterized by “either compressed… buccolingual dimension or longer … mesiodistal dimension.” we show here that these observations have greater depth in the literature. for example. we identified and illustrated the same morphological crown anomaly in 1975 (peck and peck) in two north american white orthodontic patients, describing the occurrence as a tooth shape deviation (tsd) of mnp. one case was a female with bilateral mnp1-tsd (fig. 1) and the other was a case of a male with bilateral mnp2-tsd (fig. 2). in fact, this variation had previously been recognized by dahlberg (1951) in a white female (bilateral mnp2) and by suzuki and sakai (1960) in a japanese male (bilateral mnp2), each referring to the condition as “buccolingually compressed” mandibular premolars. to our knowledge, occurrences of this anomaly have not been demonstrated for the maxillary premolars. we applied an md/fl crown index ([mesiodistal brief report: tooth shape deviations of mandibular premolars sheldon peck* department of oral and developmental biology, harvard school of dental medicine boston, ma 02115 diameter in mm ÷ faciolingual diameter in mm] x 100) to quantify the extent of this tooth shape anomaly in our two subjects: deviant mnp1 teeth, with widened mesiodistal dimension and narrowed faciolingal dimension, had an md/fl index of 122; deviant mnp2 teeth showed an md/fl index of 120-127. this compares with md/fl indices for unaffected mnp1 in whites of 90 ± 5 and for unaffected mnp2, 85 ± 5. we also found an association between mnp-tsd and a similar tsd of the mandibular incisors, commonly associated with the tendency for dental crowding (peck and peck, 1972a,b). here i report another case, a european white female showing unilateral expression of mnp1-tsd (fig. 3). from these several reported cases, i conclude that these peculiar deviations in mandibular premolar shape may derive from a developmental pinching of the faciolingual tooth mass with an associated enlargement of the mesiodistal tooth diameter. mnptsd is usually the product of reduced fl and increased fig 1. tooth shape deviations of both mandibular first premolars (mnp1-tsd) in a white female (reproduced courtesy of the angle orthodontist). fig 2. tooth shape deviations of both mandibular second premolars (mnp2-tsd) in a white male (reproduced courtesy of the angle orthodontist). address for correspondence: sheldon peck, 1615 beacon street, newton, ma 02468 email: peckslam@att.net 64 md dimensions. all elements of occlusal morphology of the affected teeth seem to be intact, just dimensionally shifted and distorted. the anomaly occurs in either sex, in either the first or second mandibular premolars independently, expressed mostly bilaterally and occasionally unilaterally. the mnp-tsd anomaly is found occurring in whites, blacks and asians. my co-workers and i are undertaking further studies of various phenotypes of this unusual dentomorphological condition. acknowledgment the author thanks dr. daniela garib for her contributions to this report. literature cited dahlberg aa. 1951. the dentition of the american indian. in: laughlin ws, editor. papers on the physical anthropology of the american indian. new york: the viking fund, p 138-176. edgar hjh, scuilli pw. 2004. elongated mandibular premolar: a new morphological variant. dental anthropology 17:24-27. peck s, peck h. 1972a. crown dimensions and mandibular incisor alignment. angle orthod 42148-153. peck h, peck s. 1972b. an index for assessing tooth shape deviations, as applied to the mandibular incisors. am j orthod 61:385-401. peck s, peck h. 1975. orthodontic aspects of dental anthropology. angle orthod 45:95-102. suzuki m, sakai t. 1960. a case of buccolingually compressed mandibular second premolar in the japanese. j anthropol soc nippon (zinruigaku zassi) 68:119-123. fig 3. tooth shape deviation of the mandibular left first premolar (mnp1-tsd) in a white female. s. peck bailey-schmidt 1995.2 pg8.jpg pg9.jpg lukacs 1996.6 pg21.jpg pg22.jpg halberstein 1995.2 pg5.jpg pg6.jpg pg7.jpg pg8.jpg lekkas and townsend 1996.1 pg2.jpg pg3.jpg pg4.jpg pg5.jpg pg6.jpg van reenen 1994.5 pg12.jpg pg13.jpg townsend et al. 1994.1 pg2.jpg pg3.jpg pg4.jpg pg5.jpg carman 1993.2 pg3.jpg pg4.jpg hill 2004.1 34 35 dental reduction and diet in the prehistoric ohio river valley molly k. hill* department of anthropology the ohio state university, columbus, ohio 43210 *address for correspondence: molly k. hill, department of anthropology, ohio state university, columbus, oh 43210. email: hill.711@osu.edu editor’s note: ms. hill’s paper was awarded first prize for 2004 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. abstract post-pleistocene dental reduction has been documented around the globe. dietary change is a common factor in many of the selectionist models explaining this reduction. the current study examines tooth size in the prehistoric ohio river valley of indiana and kentucky to determine if a dental reduction occurred from the late archaic to the mississippian periods and, if so, to see if dietary shifts are associated with dental reduction. data from 282 individuals are compiled from 21 sites that span from 5000 bc to ad 1400. these sites represent late archaic foragers, early/middle woodland early horticulturalists, late woodland mixed-economy horticulturalists, and mississippian agriculturalists. previous studies have indicated that the diet became less abrasive through time in this region but became harder from the late archaic to the early/middle woodland just to became softer again thereafter. buccolingual diameters were taken for all suitable permanent teeth. standard descriptive statistics, anova, percent differences, and rate of change were calculated for each dental measurement to determine the degree of change between the various temporal groups. it was found that a dental reduction occurred in the ohio river valley that was more pronounced in females and in the maxillary molars. the general reduction in tooth size mirrors the reduction in dietary abrasiveness. by contrast, it does not seem to follow the course of dietary hardness. dental anthropology 2004;17(2):34-44. human teeth have reduced in size worldwide since the pleistocene (kieser, 1990). dental reduction has been documented for males and females in asia, africa, australia, europe, north and south america (asia: brace, 1978; brace and hinton, 1981; brace and nagai, 1982; brace et al., 1984; and lukacs, 1985; africa: calcagno, 1989; kieser et al.,1985; australia: brace and hinton, 1981; north america: nelson, 1938; moorrees, 1957; dahlberg, 1963; wolpoff, 1971; potter, 1972; perzigian, 1976; sciulli, 1979; hinton et al., 1980, and calcagno, 1989; south america: kieser, groeneveld, preston, 1985). the cause or causes of this reduction are not entirely clear. thus, it seems prudent to document dental size in as many time periods and localities around the globe as possible in order to fully understand the factors that contributed to changes in dental size. various mechanisms have been proposed to explain dental reduction (e.g., anderson and popovich, 1977; brace, 1963; calcagno, 1989; frayer, 1978; machiarelli and bondioloi, 1986), including the accumulation of mutations, decreased gene flow, genetic drift, and selection. the probable mutation effect model (pme), proposed by brace (1963, 1964), states that teeth became smaller through time as a result of reduced selection for large teeth. however, many researchers have argued that the accumulation of random mutations would occur too slowly and it is unlikely that a directional change such as reduction would result from a random process (e.g., prout, 1964; wright, 1964; bailit and friedlaender, molly k. hill 34 35 1966; holloway, 1966; brues, 1968; byles, 1972; frayer, 1978; williams, 1978; calcagno, 1989). falconer (1967) suggests that inbreeding could result in the reduction of a phenotypic trait. however, many studies have shown that inbreeding is uncommon in modern humans (bailit, 1966; wobst, 1976; frayer, 1978). it is also unlikely that genetic drift is solely responsible for dental reduction (sciulli and mahaney, 1991). genetic drift more frequently eliminates those traits (i.e., alleles) that are least common in a population. therefore, it is improbable that small teeth could have evolved from populations with predominantly larger teeth by genetic drift alone (calcagno, 1989). however, genetic drift cannot be ignored when comparing small, geographically isolated populations where interpopulation gene flow might have been significantly reduced. other models for dental reduction suggest that directional selection for smaller teeth resulted as masticatory stress declined and dietary pathogenesis increased (calcagno, 1989; frayer, 1978; see also anderson and popovich, 1977; bailit and friedlander, 1966; brues, 1966; goodman, 1991; holloway, 1966; jolly, 1971; leblanc and black, 1974; prout, 1964; sciulli and mahaney, 1991). another theory, the “somatic budget effect,” suggests that smaller teeth are less costly to form and thus conserve energy in nutrientpoor conditions (jolly, 1971). human dental reduction has been documented in africa, asia, europe, and north america and all reductions were accompanied by changes in subsistence. specifically, many studies have reported that the largest teeth can be found in the older hunter/gatherer populations. tooth size decreases fig. 1. indiana and kentucky sites used in this study. la = late archaic, e/mw = early/middle woodland, lw = late woodland, ms = mississippian. sample sizes are indicated in parentheses with the first number corresponding to the number of males and the second to the number of females. dental reduction 36 37 through time as populations adopted more processed, horticultural diets, and ultimately, agriculture. the story of dental reduction, however, is still unclear. in some places dental reduction seems to be specifically associated with changes in diet, while in other places it appears that teeth change with the adoption of specific technologies like pottery. a common denominator between the different selectionist models for dental reduction is diet, because all models suggest that what people eat can eventually affect tooth size. studies that examine how changes in dental size co-occur with changes in subsistence and diet may therefore help to clarify the specific nature of the forces that were at play in human prehistory. the current study investigates the association between diet and tooth size by comparing dental metrics among four ohio river valley populations that date from 5,000 to 500 years ago, each with its own well-documented subsistence strategy. the study populations include representative foraging, horticultural, and agricultural groups from indiana and kentucky. the initial goal is to determine if dental reduction occurred from late archaic to the mississippian periods. if a temporal reduction is found, the second goal will be to determine which dietary shift is associated with the most pronounced change. materials and methods samples the 21 sites from which human remains were studied span approximately 6500 years from 5000 bc (the late archaic indian knoll site) to ad 1400 (the mississippian angel site). these sites cluster in southern indiana and northern kentucky near or within the ohio river valley (including the green and white river valleys) (fig. 1). it is believed that these sites are culturally distinct entities that displayed spatial continuity and shared biological and some cultural influences throughout time (griffin, 1983; schroedl, boyd, and davis; 1990; muller, 1986). data from 282 individuals were compiled for this study. refer to figure 1 for sample sizes and site locations. a portion of the study sample is comprised of unpublished dental metric data that were collected by schmidt in 1998. the remainder and majority of the sample are data that were collected by hill. interobserver error between schmidt and hill was found to be insignificant in a previous odontometrics study (schmidt and hill, 2001). subsistence in the prehistoric ohio river valley. the ohio river valley is broadly defined as the areas adjacent to the ohio river in illinois, indiana, ohio, kentucky, and pennsylvania. evidence suggests that this area was continuously occupied in prehistory from between about 10,000 and 12,000 years (cassidy, 1984), and the subsistence strategies for the prehistoric populations that occupied this region have been adequately documented. the archeological record of the ohio river valley suggests that the area’s first inhabitants were foragers. foraging was the primary subsistence strategy for over 5,000 years when eventually some of the late archaic people adopted horticulture around 3,000 and 4,000 years ago. the horticultural early/middle woodland followed the late archaic, which was in turn followed by the late woodland around 1,400 years ago. people from these time periods had a mixed economy of horticulture with some maize agriculture. by the mississippian, about 700 years ago, maize agriculture was the predominant subsistence strategy (scarry, 1993). diet and food preparation. for the most part, there is a trend toward a softer/less abrasive and more cariogenic diet in the midwest (smith, 1984; schmidt, 1998; schmidt, 2001). specifically, the transition from the late archaic to the early/middle woodland saw the diet changing in both sexes from extremely abrasive to less abrasive (decreased microwear scratch widths) and very hard (increase in frequency of microwear pits) (schmidt, 1998, 2001). the late archaic diet probably consisted of wild plants and riverine resources contaminated by sand (hence the abrasiveness). the early/middle woodland diet relied very heavily on nuts. both diets were based on wild foods, probably required significant masticatory processing that was stressful to the teeth and jaws, and neither diet was particularly cariogenic. however, the early/middle woodland diet was facilitated with pottery, whereby this increase in food processing technology removed much of the abrasiveness from the diet. the hard and less abrasive early/middle woodland diet was replaced by the mixed diet of the late woodland, which had the hardness in both males and females of the middle woodland diet but was far more cariogenic. the microwear data do not change much between the early/middle and late woodland periods and the macrowear evidence groups the early/middle woodland and late woodland periods together as well (schmidt, 1998). these types of data indicate that although the introduction of maize in the late woodland period is very important archeologically, initially it does not create a significant dietary transition. the mississippian diet was almost certainly based on maize agriculture (schmidt, 1998), and was considerably softer, somewhat less abrasive, and far more cariogenic than all other time periods. from what is known of the these time period in north america, and from the sites used in this study specifically (schmidt, 1998, 2001), the significant changes in dietary abrasiveness occurred between the late archaic and early/middle woodland m.k. hill 36 37dental reduction periods. the diet became significantly softer and less abrasive (to a smaller degree) between the late woodland and mississippian periods (agricultural transition). however, in the present study, the late woodland to the mississippian transition could not be examined because the late woodland sample was deficient. although maize was introduced during the late woodland period, the transition from the early/ middle woodland to the late woodland was not marked by any significant differences in microwear or macrowear nor with much change in dental caries (schmidt, 1998). therefore, examining the early/ middle woodland to mississippian transition in place of the late woodland to mississippian transition may not be all that problematic. tooth size standard buccolingual (bl) diameters were taken from all available permanent teeth on the left side of the jaws. teeth from the right side were substituted in cases where teeth from the left side were unavailable or inadequate, i.e., if they were too heavily worn, fractured, or deciduous. incisors were not suitable for measurements due to heavy wear. the resulting sample was thus limited to canines, premolars, and first through third molars of the maxilla and mandible. buccolingual diameters were measured using mitutoyo fine point digital calipers, with an accuracy of 0.01 mm, according to methods outlined in buikstra and ubelaker (1994) and kieser (1990). the bl diameter was taken as the greatest distance perpendicular to the mesiodistal diameter. sex the majority of the metric data were collected from individuals for whom sex could be determined. sex was determined by analyzing skull and pelvis morphology following standards outlined by buikstra and ubelaker (1994). in a few instances sex determination was augmented by information from previous osteology reports in which sex was established by earlier researchers. sex determinations for the majority of the individuals studied by the author were consistent with the published data. the original sample included 56 individuals for whom sex was not determined. a series of 16 multivariate dental sexing formulae were applied to the individuals for whom sex was established to determine their efficacy. five formula yielded percent correct values higher than 70 percent for the current study sample. these five formulae were derived from two studies. one formula was derived from the analysis of prehistoric remains from the dickson mound site in illinois (ditch and rose, 1972). the remaining four formulae were derived from a study of a prehistoric population from the eastern tennessee valley (scott and parham, 1979). sex was then estimated for each of the 56 undetermined individuals using the five formulae. the results from the different formulae were in agreement for 17 of the 56 individuals, and so for these 17, the estimated sex was entered into the dataset. therefore, the final dataset includes 152 males and 130 females and no unsexed individuals. statistical analysis standard descriptive statistics were computed for each population including means, standard deviations, and variances. the means were compared among the four temporal groups while controlling for sex. the percent difference and rate of change were calculated to determine the degree of change between the four temporal groups in order to determine where the greatest changes occurred. the percent difference between the means was calculated by subtracting the mean tooth size from the more recent group from that of the older group, and dividing the difference by the late archaic e/m woodland late woodland mississippian x n sd x n sd x n sd x n sd uc 8.69 37 0.526 8.68 23 0.475 8.91 17 0.522 8.78 15 0.531 lc 7.90 40 0.530 7.95 24 0.465 8.26 20 0.529 8.12 20 0.518 up3 9.66 28 0.725 9.66 22 0.609 9.29 14 1.133 9.79 13 0.649 lp3 8.38 32 0.428 8.29 28 0.456 8.28 21 0.538 8.25 18 0.632 up4 9.53 28 0.720 9.53 22 0.524 9.44 14 0.860 9.74 13 0.606 lp4 8.48 30 0.445 8.59 27 0.443 8.72 24 0.471 8.63 21 0.522 um1 12.05 28 0.495 12.12 16 0.529 12.11 16 0.613 11.78 18 0.396 um2 12.05 31 0.614 11.74 17 0.723 11.81 18 0.680 11.86 19 0.823 um3 11.52 30 0.755 10.88 25 0.758 11.09 13 0.750 11.23 17 0.620 lm1 11.29 35 0.467 11.21 24 0.430 11.30 22 0.566 10.97 19 0.460 lm2 10.90 35 0.551 10.76 24 0.507 10.70 21 0.620 10.63 24 0.534 lm3 10.91 32 0.752 10.70 28 0.702 10.69 14 0.456 10.59 21 1.00 table 1. mean bl diameters ( x ), sample size (n), and standard deviation (sd) for males through time 38 39 mean of the older group and multiplying the quotient by 100 (calcagno, 1989): x -x x 1001 2 1 ( ) x 1 = mean tooth size for older group x 2 = mean tooth size for more recent group the extent or rate of change was calculated by the following formula, which controls for time differences between groups. the resulting rate is in terms of change per one million years. log x -log x time 1 2 x 1 = mean tooth size in sample 1 x 2 = mean tooth size in sample 2 time = interval separating the two samples in millions of years. this formula allows for the visualization of the amount of change between temporally-adjacent populations. rate was calculated between the late archaic and early/middle woodland periods (separated by approximately 3,639 years), the early/ middle woodland and the mississippian periods (separated by approximately 1,485 years), and the late archaic and mississippian periods (separated by approximately 5,124). these three transitions were compared because they represent important dietary transitions, and are divided by comparable spans of time. tests for normality and homoscedasticity were late archaic e/m woodland late woodland mississippian tooth x n sd x n sd x n sd x n sd uc 8.44 34 0.436 8.63 21 0.473 8.39 16 0.599 8.34 20 0.500 lc 7.44 31 0.435 7.47 15 0.341 7.40 15 0.344 7.29 25 0.520 up3 9.66 32 0.767 9.57 21 0.478 9.27 15 0.702 9.32 18 0.419 lp3 8.17 33 0.470 7.99 18 0.366 7.45 13 0.906 7.82 21 0.552 up4 9.45 30 0.565 9.19 20 0.435 9.13 16 1.380 9.42 18 0.441 lp4 8.54 33 0.565 8.33 18 0.392 7.96 13 1.099 8.31 23 0.563 um1 11.87 30 0.470 11.45 15 0.517 11.75 19 0.678 11.52 22 0.539 um2 11.82 31 0.447 11.51 20 0.397 11.29 18 1.150 11.29 17 0.477 um3 11.31 26 0.559 10.83 20 0.624 11.04 15 0.713 10.72 15 0.784 lm1 11.01 33 0.402 10.91 15 0.431 10.78 18 0.543 10.76 22 0.562 lm2 10.83 34 0.392 10.57 17 0.403 10.34 16 0.569 10.40 27 0.511 lm3 10.92 26 0.519 10.44 16 0.603 10.17 14 0.576 10.29 23 0.651 table 2. mean bl diameters ( x ), sample size (n), and standard deviation (sd) for females through time sex tooth n d.f. p f-ratio m um3 85 3 0.018 3.528 f lp3 85 3 0.002 5.398 f um1 86 3 0.044 2.821 f um2 86 3 0.018 3.563 f um3 76 3 0.025 3.307 f lm2 94 3 0.001 6.122 f lm3 79 3 0.000 6.964 table 3. anova results for measurements that significantly changed through time† †n = sample size, d.f. = degrees of freedom, p = probability value. sex tooth n d.f. p f-ratio m uc 92 3 0.469 0.853 m lc 104 3 0.059 2.567 m up3 77 3 0.356 1.097 m up4 77 3 0.696 0.482 m lp3 99 3 0.804 0.330 m lp4 102 3 0.284 1.285 m um1 78 3 0.172 1.711 m um2 85 3 0.447 0.897 m lm1 100 3 0.091 2.220 m lm2 104 3 0.274 1.313 m lm3 95 3 0.476 0.839 f uc 91 3 0.273 1.321 f lc 86 3 0.510 0.777 f up3 86 3 0.140 1.878 f up4 84 3 0.421 0.950 f lp4 87 3 0.078 2.352 f lm2 87 3 0.213 1.530 table 4. anova results measurements that did not significantly change through time† †n = sample size, d.f. = degrees of freedom, p = probability value. m.k. hill 38 39dental reduction conducted on the samples to determine if they met the assumptions of analysis of variance (anova). a total of 24 kolmogorov-smirnov tests run on each bl diameter and for each sex revealed that all samples were normally distributed (for every tooth type and sex and measurement therein). levene’s test for homoscedasticity did not reject equal variances among any of the samples. anovas were conducted on the bl diameters for each sex independently, for a total of 24 anovas. a protected t-test, fisher ’s least significant difference (lsd), was then conducted as a sensitive post hoc test in order to determine where significant differences existed. all tests used an alpha value of 0.05 as the criterion for significance. results the descriptive statistics are listed in tables 1 and 2. time was significant in seven of these 24 anovas (tables 3 and 4). the majority of significant tests (n = 6) involved the molar measurements, with two tests being significant for lower molars (fig. 3) and four tests being significant for upper molars (fig. 2). the sex tooth significant difference f lp3 la – lw (reduction) la – ms (reduction) f um1 la – e/mw (reduction) la – ms (reduction) f um2 la – lw (reduction) la – ms (reduction) f um3 la – e/mw (reduction) la – ms (reduction) f lm2 la – lw (reduction) la – ms (reduction) f lm3 la – e/mw (reduction) la – lw (reduction) la – ms (reduction) m um3 la – e/mw (reduction) table 5. post hoc results for significant measurements late archaic–em woodland em woodland–mississippian total sex tooth rate % difference rate % difference rate % difference m uc -0.14 -0.12 +3.35 +1.15 +0.87 +1.04 m lc +0.75 +0.63 +6.19 +2.14 +2.33 +2.78 m up3 0.00 0.00 +3.91 +1.35 +1.13 +1.35 m lp3 -1.29 -1.07 -1.41 -0.48 -1.33 -1.55 m up4 0.00 0.00 +6.37 +2.20 +1.85 +2.20 m lp4 +1.54 +1.30 +1.36 +0.47 +1.49 +1.77 m um1 +0.69 +0.58 -8.32 -2.81 -1.92 -2.24 m um2 -3.11 -2.57 +2.97 +1.02 -1.35 -1.58 m um3* -6.82 -5.56 +5.59 +1.93 -3.22 -3.73 m lm1 -0.85 -0.71 +2.34 +0.80 +0.08 +0.09 m lm2 -1.54 -1.28 -3.55 -1.21 -2.13 -2.48 m lm3 -2.32 -1.92 -3.02 -1.03 -2.52 -2.93 f uc +2.66 +2.25 -10.00 -3.36 -1.01 -1.18 f lc +0.48 +0.40 -7.13 -2.41 -1.73 -2.02 f up3 -1.12 -0.93 -7.74 -2.61 -3.04 -3.52 f lp3* -2.66 -2.20 -6.29 -2.13 -3.71 -4.28 f up4 -3.33 -2.75 +7.23 +2.50 -0.27 -0.32 f lp4 -2.97 -2.46 -0.70 -0.24 -2.31 -2.69 f um1* -4.30 -3.54 +1.78 +0.61 -2.54 -2.95 f um2* -3.17 -2.62 -5.64 -1.91 -3.89 -4.48 f um3* -5.18 -4.24 -2.99 -1.02 -4.54 -5.22 f lm1 -1.09 -0.91 -4.05 -1.37 -1.95 -2.27 f lm2* -2.90 -2.40 -4.74 -1.61 -3.43 -3.97 f lm3* -5.36 -4.40 -4.23 -1.44 -5.04 -5.77 †rate of change calculated in mm/million years. percent difference calculated in mm/years separating two groups. a reduction in tooth size is indicated by (-) and an increase by (+). teeth that changed significantly through time are indicated by (*). table 6. rate of change and percent difference for the transitions from the late archaic to the early/middle woodland, the early/middle (em) woodland to the mississippian, and the late archaic to mississippian periods (total)† 40 41 only other significant difference was observed in lower third premolars (fig. 3) and no significant differences were observed for canines. only one of the 12 anovas conducted for males were significant for time, and 6 of the 12 anovas conducted for females were significant for time (tables 3 and 4). rate of change and percent differences the rate of change and percent differences were calculated in order to better understand the patterning of change across the different time periods (table 6). the discussion of rates and percent change is limited to those teeth that changed significantly through time. only two of the significant transitions were represented by an increase in tooth size. the male um3 showed a 1.93% increase between the early/middle woodland and mississippian periods. furthermore, the female um1 showed a 0.61% increase during the same transition. the remaining significant teeth display reductions during all three transitions. the percent change is most often largest between the early/middle woodland and mississippian periods (five comparisons). the rate of change, however, is very similar between the two transitions. it is fastest between the late archaic and early/middle woodland periods in four comparisons and between the early/middle woodland and mississippian three times. discussion and conclusion the purpose of this study was to determine if a dental reduction occurred through time and to determine if specific dietary shifts are associated with specific patterns or rates of change. it is apparent that a reduction in tooth size did occur between 4,000 bc and ad 1,400 in this prehistoric ohio river valley sample. a number of specific points merit further discussion: several of the significant tests were for maxillary molars; no canine measurements changed significantly through time; the majority of the significant results were for females. maxillary molars time is significant for more maxillary molar measurements than for any other measurement analyzed in this study, and their mean values clearly decrease from the late archaic to mississippian time periods. these results suggest that maxillary reduction exceeds that of the mandible, which is consistent with other dental reduction studies (e.g., wolpoff, 1971; perzigian, 1976; leblanc and black, 1974; sofaer et al., 1971; sofaer, 1973; lukacs, 1985). in fact, lukacs (1985) observed a reduction in maxillary second molars and none in mandibular third molars, suggesting that even later-erupting lower molars do not change to the extent of earlier-erupting upper molars. therefore, although other studies have shown that later-erupting third molars are more variable in morphology and size (e.g., sofaer et. al., 1971), lukacs’ study implies that the maxillary teeth are still changing more despite the fact that they are earlier-erupting teeth. since the end of the pleistocene (after 10,000 bp), the rate of maxillary reduction has consistently surpassed that of the mandible (brace, rosenberg, and hunt, 1987). frayer (1978) suggests that an increase in the rate of change implies an increase in the severity of the force behind the change. according to this logic, the force behind the change in the maxillary dentition would have been greater than that behind the mandible. it is possible that the maxillary teeth are reducing in accordance with an overall reduction of the maxillofacial complex (larsen, 2002). the maxillofacial complex consists of the maxilla, surrounding facial bones, and teeth. studies have shown that the reduction in the face has occurred at a much faster pace than that of the teeth alone, although strong correlations between tooth size and the overall reduction of this complex have been documented (see summaries in kieser, 1990). as the maxillofacial complex reduced, the available space for developing teeth also reduced. since the mandible is more flexible in its development (kieser, 1990), it seems fig. 2. display of significant changes in female (f) maxillary first through third molars and male (m) maxillary third molar through time. fig. 3. display of significant changes in female mandibular teeth through time. m.k. hill 40 41dental reduction plausible that it may have been able to accommodate the slower reducing, large teeth, whereas the maxilla would not. canines canines did not change significantly through time in this study. it would benefit the interpretation of these results if other anterior teeth were available for comparison, as the majority of holocene dental reduction studies agree that posterior dental reduction is more marked than that of the anterior teeth (sofaer et al., 1971; sofaer, 1973). for example, calcagno (1989) observed a reduction only in molars between agricultural and intensive agricultural groups. sciulli (1979) reported a reduction in both molars and incisors, but not for canines. in this study only one premolar significantly reduced through time, the lp3 of females. therefore its seems, at least in part, that the reduction observed in this study is more marked as one proceeds posteriorly through the jaw, which is consistent with the previously-mentioned studies. females vs. males in the overwhelming majority of anovas in this study, time was significant only for females. sciulli (1979), larsen (1981), and calcagno (1989) also reported more significant changes in females through time. in sciulli’s (1979) study, the patterns of sexual dimorphism and variability did not change through time, although females were often larger than males in the earlier glacial kame group (3 anterior teeth and 3 posterior teeth), seldom larger in the adena group (3 anterior teeth and 1 posterior tooth), and rarely larger in the hopewell group (1 anterior tooth). this indirectly suggests that through time the females are reducing more markedly (and especially in the posterior dentition) than the males. larsen (1981) found a reduction only in females between pre-agricultural (2,200 bc – ad 1,150) and mixed economy (ad 1,150) groups from the georgia coast. calcagno (1989) noted a greater reduction in females. although 30 of the 32 measurements were significant for males in his study, and only 26 of the 32 were significant for females, the percent reduction was much greater for females through time. a few explanations have been proposed to clarify why females changed more markedly over the time span observed here. the majority of the explanations suggest a differential environmental impact on each sex. for example, garn and associates (1972) suggest that because males trail females in permanent tooth eruption, their dentition might be more plastic to the effects of a selection event. although, this reasoning seems logical, it is also plausible that males and females do not differ in eruption by enough time to make a considerable impact. dental caries and wear have also been documented to vary by sex and therefore dental measurements may reflect this (perzigian, 1976; hinton et al., 1980; schmidt 1998). these two variables, caries and wear, are strongly linked to health and diet. one thought is that females react to stressors differently than males, resulting in higher incidences of dental caries. in many populations the frequency of certain pathological conditions (such as caries) is relatively high in females (cohen and armelagos, 1984). another explanation implies a long-term selection event that may have affected females differently. larsen (1981) suggests that reduction is only found in females because it is only the females whose diet and subsistence dramatically changed from pre-agriculture to a mixed economy. he explains that females were burdened by the responsibilities of agriculture while the male subsistence strategy did not change (males continued to hunt). however, schmidt found no significant difference between male and female microwear and macrowear for the majority of samples used in this study (1998, 2001). diet and dental reduction the second goal of this study was to address the role of diet in dental reduction. the premise is that reduction is most significant between those populations where dietary change is most marked, i.e., became noticeably less abrasive, softer and/or more cariogenic. when comparing the two transitions by looking at the post hoc test results (late archaic to early/ middle woodland and early/middle woodland to mississippian) it seems as if the first transition is the more significant. the mean measurements of the um1, um3, and lm3 for females and um2 for males are significantly different between the late archaic and early/middle woodland periods, whereas no measurements are significant in the later transition. these results are very similar to those of sciulli and mahaney (1991), who found a significant reduction only between late archaic and middle woodland ohioans. the authors conclude that the advent of pottery at the end of the late archaic is the most significant change that led to dental reduction. their conclusion is not without support, as brace consistently argued that the incorporation of pottery and more processed foods was the reason that dental reduction accelerated at the end of the pleistocene (e.g., brace, rosenberg and hunt, 1987). the percent difference and rates of change show very comparable results. these values are often used in odontometric studies of this kind, but it must be stressed that these values are not being compared here with any statistical methods. in other words, it is obvious by observing the percentages that the differences are more often greater during the second transition; however, the significance of those values has not been demonstrated here. despite this, the results listed in table 6 do provide a descriptive display of the amount and rate of 42 43 the significant and non-significant changes. in the current study the average maxillary reduction (as averaged from the significant teeth in table 6 is 0.799%/1,000 years, and the mandibular rate is 0.911%/1,000 years. these results indicate a minimal amount of reduction, especially compared to those observed by leblanc and black (1974) who observed a rate of 2.0 percent every 1,000 years, since the end of the pleistocene, with the maxillary rate exceeding that of the mandible (leblanc and black, 1974). the rates observed here may be artificially low since the author took a very conservative approach to calculating rate (only for those teeth that changed significantly through time in the anova). furthermore, the rates calculated in this study represent one “population” in the world that lived during the holocene period, and it is likely that these rates fit well within the range of other dental reduction rates gathered from various other parts of the world, including north america. finally, there is no direct way of knowing whether the rate of dental reduction increased in north america at this time, for material from earlier time periods is not yet available for study. while these results are consistent with other studies that interpreted reduction as a certain selection event, these results do have certain implications for how one interprets the force behind the selection. during the early/middle woodland the diet is very hard, yet it has become less abrasive because of processing techniques that removed much of the sand from the food. processing techniques changed somewhat from the early/middle woodland to the mississippian periods, but it is the food that changed dramatically. studies have shown that agricultural diets are markedly softer and somewhat less abrasive than those of previous time periods (e.g., schmidt, 1998). therefore the reduction shown in this study and many others may be more associated with a reduction in dietary abrasiveness rather than hardness. dietary abrasiveness in a dental reduction context. earlier experimental studies tended to focus on dietary hardness/softness as a variable that controlled jaw and tooth size. for example, animals that were fed softer diets in laboratory experiments tended to have craniofacial shortening and smaller jaws in general and narrower maxillary arches in particular (corruccini, 1991; see also larsen, 1997). while studies like this have concluded that the reduction in masticatory apparatus is associated with a transition to softer foods (e.g., frayer, 1978; hinton et al., 1980; larsen, 1981; sciulli, 1979; sciulli and mahaney, 1991) it is important to note that considering dietary abrasiveness as a factor in dental reduction is a relatively new approach. moreover, the results herein that state dietary abrasiveness is associated with human dental reduction do not obviate conclusions stating that dietary hardness/softness can affect other components of the masticatory complex. conclusion a previously undocumented reduction in tooth size was found among populations dating from the late archaic to the mississippian periods from the ohio river valley in indiana and kentucky. these results are consistent with numerous other studies that have found dental reduction in comparable populations around the world. the reduction was most pronounced in females and in maxillary teeth. both the number of significant maxillary reductions and the rate of maxillary reduction were greater than those of the mandible. dental reduction seems to be associated with a significant reduction in dietary abrasiveness. as the advent of pottery and more efficient food processing techniques removed sand from much of the same types of foods between the late archaic and early/middle woodland periods, teeth reduced at a steady, yet comparatively slow pace. acknowledgements i would like to thank the indiana university department of anthropology, the glenn black laboratory at indiana university, and the webb museum of anthropology at the university of kentucky for the opportunity to study the remains housed at their institutions. special thanks, also, to chris schmidt for his advising and assistance during this project. in addition, i would like to thank stephen nawrocki and paul sciulli for their assistance and editing. funding provided by a grant from the indiana academy of science. literature cited anderson dl, popovich f. 1977. dental reduction and dental caries. am j phys anthropol 47:381-386. bailit hl, friedlaender js. 1966. tooth size reduction: a hominid trend. am anthrop 68:665-672. brace cl. 1963. structural reduction in evolution. am nat 97:39-49. brace cl. 1964. the probable mutation effect. am nat 98: 453-455. brace cl. 1978. tooth reduction in the orient. asia perspectives 19:203-219. brace cl, hinton rj. 1981. oceanic tooth size variation as a reflection of biological and cultural mixing. cur anthrop 22:549-557. brace cl, nagai m. 1982. japanese tooth size, past and present. am j phys anthropol 59:399-411. brace cl, xiang-qing s, zhen-biao z. 1984. prehistoric and modern tooth size in china. in: smith fh, spencer f, editors. the origin of modern humans. new york: alan r. liss, p 485-516. brace cl, rosenburg kr, hunt kd. 1987. gradual change in human tooth size in the late pleistocene and postm.k. hill 42 43dental reduction pleistocene. evol 41:705-720. brues am. 1968. mutation and selection—a quantitative evaluation. am j phys anthropol 25:169-170. buikstra je, ubelaker dk. 1994. standards for data collection from human skeletal remains. arkansas archaeological survey research series, no. 44. byles rh. 1972. limiting condition for the operation of the probable mutation effect. soc biol 19:29-34. calcagno jm. 1989. mechanisms of human dental reduction: a case study from post-pleistocene nubia. lawrence:university of kansas publications in anthropology, no. 18. cassidy cm. 1984. skeletal evidence for prehistoric subsistence adaptation in the central ohio river valley. in: cohen md, armelagos gj, editors. paleopathology at the origins of agriculture. orlando: academic press, p 307-345. cohen mn, armelagos gj. 1984. paleopathology at the origins of agriculture. orlando: academic press. corruccini rs. 1991. anthropological aspects of orofacial and occlusal variation and anomalies. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley liss, p 295-323. dahlberg aa. 1963. dental evolution and culture. hum biol 35:237-249. ditch le, rose jc. 1972. a multivariate dental sexing technique. am j phys anthropol 37:61-4. falconer ds. 1967. quantitative genetics. edinburgh: oliver and boyd. frayer dw. 1978. evolution of the dentition in the upper paleolithic and mesolithic europe. lawrence: university of kansas publications in anthropology, no. 10. garn sm, wertheimer f, sandusky st, mccann mb. 1972. advanced tooth emergence in negro individuals. j dent res 51:1506. goodman ah. 1991. health, adaptations, and maladaptation in past societies. in: bush h, zvelebil m, editors. health in past societies: biocultural interpretation of human skeletal remains in archaeological contexts. british archaeological reports, international series, p 279-293. griffin jb. 1983. the midlands. in: jennings jd, editor. ancient north america. new york: wh freeman and company. hinton rj. 1983. relationships between mandibular joint size and craniofacial size in human groups. arch oral biol 28:37-43. hinton rj, smith mo, smith fh. 1980. tooth size changes in prehistoric tennessee indians. hum biol 52:229-245. holloway rl. 1966. structural reduction through the probable mutation effect. am j phys anthropol 25:7-11. jolly cj. 1971. the seed eaters: a new model of hominid differentiation based on a baboon analogy. man 5:5-26. kieser ka. 1990. human adult odontometrics. new york: cambridge university press. kieser ka, groeneveld ht, preston cb. 1985. an odontometric analysis of the lengua indians dentition. hum biol 57:611-620. larsen cs. 1981. functional implications of postcranial size reduction on the prehistoric georgia coast, usa. j hum evol 10:489-502. larsen cs. 1997. bioarchaeology: interpreting behavior from the human skeleton. cambridge: cambridge university press. larsen cs. 2002. plio-pleistocene human evolution bioarchaeology of the agricultural transition. in: unger ps, teaford mf, editors. human diet: its origins and evolution. connecticut: bergin and garvey press, p 19-37. macchiarelli r, bondioli l. 1986. post-pleistocene reduction in human dental structure: a reappraisal in terms of increasing population density. hum evol 1:405-418. moorrees cfa, reed rb. 1954. correlations among crown diameters of human teeth. arch oral biol 9:685-97. muller j. 1986. archaeology of the lower ohio river valley. new york: academic press. nelson ct. 1938. the teeth of the indians of pecos pueblo. am j phys anthropol 23:261-293. perzigian aj. 1976. the dentition of the indian knoll skeletal population: odontometrics and cusp number. am j phys anthropol 44:113-122. potter rhy. 1972. univariate versus multivariate differences in tooth size according to sex. j dent res 51:716-722. prout t. 1964. observations on structural reduction in evolution. am nat 98:239-249. scarry cm. 1993. foraging and farming in the eastern woodlands. gainesville, fl: university of florida press. schmidt cw. 1998. dietary reconstruction among prehistoric humans from indiana: an analysis of dental macrowear, dental pathology, and dental microwear. ph.d. dissertation, purdue university. schmidt cw. 2001. dental microwear evidence for a dietary shift between two non-maize reliant prehistoric human populations from indiana. am j phys anthropol 114: 139-145. schmidt cw, hill mk. 2001. finding and correcting error when using the robustness index to calculate occlusal area. paper presented at the 7th annual meeting of the midwest bioarcheology and forensic anthropology association, wichita, ks. schroedl f, boyd c, davis r. 1990. explaining mississippian origins in east tennessee. in: smith b, editor. the mississippian emergence. washington, dc: the smithsonian institution. sciulli pw. 1979. size and morphology of the permanent dentition in prehistoric ohio valley amerindians. am j phys anthropol 50:615-628. sciulli pw, mahaney mc. 1991. a test of phenotypic evolution in prehistoric ohio native americans. hum biol 63: 499-511. scott gt, parham kr. 1979. multivariate dental sexing formulae: discrimination of the sexes with an east tennessee mississippian skeletal sample. tenn anthropol 4: 44 45 189-198. smith bh. 1984. pattern of molar wear in hunter-gatherers and agriculturalists. am j phys anthropol 62:39-56. sofaer ja. 1973. a model relating developmental interaction and differential evolutionary reduction of tooth size. evol 27:427-434. sofaer ja, bailit hl, maclean cj. 1971. a developmental basis for differential tooth size reduction during hominid evolution. evol 25:509-517. williams rc. 1978. the probable mutation effect: neutral alleles and structural reduction. hum biol 50:173-181. wobst hm. 1976. locational relationships in paleolithic society. in ward rh, wiess km, editors. the demographic evolution of human populations. new york: academic press, p 49-58. wolpoff mh. 1971. metric trends in hominid dental evolution. cleveland, oh: case western university press. wright s. 1964. pleiotropy in the evolution of structural reduction and of dominance. am nat 98:65-69. m.k. hill call to order: the meeting was called to order at 7:50 p.m., by president joel irish. old business: daa website: alma adler reported that the new improved website was almost ready to be made available to the public. the site will be hosted by university of tennessee, health science center, memphis, tn. new business: 1. retirement of officers: joel irish ended his term as president. 2. instatement of new officer. debbie guatelli-steinberg ended her term as president-elect and began her term as president. 3. election of new officer: simon hillson was elected by unanimous vote to the position of presidentelect. 4. a. a. dahlberg student prize: the winner of the 2004 competition was molly k. hill, at ohio state university, for her paper entitled “dental reduction and diet in the prehistoric ohio river valley.” she received $200, a certificate of award, a year’s free membership in the daa, and will have her article published in the journal [editor’s note: this article starts on page 34]. celeste marie gagnon, university of north carolina, was named first runner up for her paper entitled “food and the state: bioarchaeological investigations of diet in the moche valley of perú.” celeste received $50, a certificate of award, a year’s free membership in the daa, and will have her article published in the journal [see page 45, this issue]. 5. editor’s report: edward harris reported that the next issue of the journal was ready for publication. he also urged faculty and students to submit articles for consideration to the journal. 6. secretary-treasurer’s report. heather edgar reported that as of april 11th, 2004, the daa has $3,891.91 in operations funds, and $1,843.91 in the aa dahlberg prize fund. there are 161 members in the association who are current with their dues, and 126 who are delinquent from between one and three years. an e-mail message is going to be sent to all members (63) who are two and three years behind in their membership dues. 7. additional topics: joel irish issued for ideas for a dental anthropology symposium for next year’s meetings. greg nelson was named new book review editor for dental anthropology adjournment: joel irish adjourned the meeting at 8:40 p.m. the meeting was followed by a period of socializing around the daa cash bar. submitted by: heather j.h. edgar daa secretary-treasurer minutes of the 19th annual dental anthropology association business meeting: april 15th, 2004, tampa, florida hawkey 1994.4 pg11.jpg pg12.jpg pg13.jpg haddow and lovell 2003.2 72 73 analyses of ancient near eastern dentitions are sparsely represented in the literature, whether concerning pathology (e.g., krogman, 1940; carbonell, 1966), non-metric traits (e.g., dahlberg, 1960; rathbun, 1972), or metric variation (e.g., macchiarelli, 1989; rosenzweig and zilberman, 1967, 1969). one reason for this may be that excavations of human remains at such classic sites as kish (mackay, 1925; watelin and langdon, 1934), and ur (wooley, 1934), were conducted in the early first half of the twentieth century, a time when studies of the teeth were not considered essential components of skeletal analysis. unfortunately, although dental anthropological studies have become more common, the political climate of the near east in recent decades has prevented research at many ancient mesopotamian sites. as a consequence, some researchers have begun to explore the rich archaeological history of northern mesopotamia, a region long ignored by archaeologists who, in the past, preferred to study agricultural origins and state emergence in the southern iraqi floodplain. as a result of excavations conducted in northeastern syria in the last quarter of the twentieth century, a new, albeit limited, set of archaeological human remains is available for analysis. this paper presents the results of an odontometric analysis of human skeletal remains from the northern mesopotamian site of tell leilan, syria, and compares these results to odontometric data from other regions and time periods of the near east in order to examine diachronic dental size variation. documentation of dental reduction trends based on odontometric observation of archaeological populations has been achieved in a number of areas of the world for postpaleolithic asia (brace, 1978; lukacs and hemphill, 1991) and upper paleolithic-mesolithic europe (frayer, 1977, 1978), but more work in regions and time periods previously unexamined by dental anthropologists will enable researchers to more accurately understand the evolutionary processes involved in hominid dental reduction, one of the most widely reported, and hotly debated trends in the study of human evolution (brace, 1963, 1964, 1978; brace et al., 1987, 1991; calcagno, 1989; gibson and calcagno, 1989; kieser, 1990; macchiarelli and bondioli, 1984). this study, then, is intended as a contribution to the odontometric history of mesopotamia and as a summary compilation and comparison of previously conducted odontometric work as it relates to the phenomenon of dental reduction within the ancient near east. materials and methods tell leilan is located on the fertile habur plains of northeastern syria. occupied from the mid-sixth millennium bc, the site became one of the three major urban centers of subir during the emergence of complex state society in northern and southern mesopotamia in the mid-third millennium bc (weiss et al., 1993). during the tell leilan iib period (~2300-2200 bc), the imperial interests of the southern mesopotamian ruler sargon, and his successors, brought tell leilan and the rest of subir under akkadian domination (gibbons, 1993; weiss et al., 1993). at approximately 2200 bc, tell leilan was abandoned for some 300 years, due to severe metric analysis of permanent and deciduous teeth from bronze age tell leilan, syria scott haddow and nancy c. lovell* department of anthropology, university of alberta, edmonton, alberta, canada *correspondence to: dr. nancy c. lovell, department of anthropology, 13-15 tory building, university of alberta, edmonton, alberta t6g 2h4, canada. e-mail: nancy.lovell@ualberta.ca. abstract between 1979 and 1989 the skeletal remains of 21 adults and 38 children, yielding 317 permanent and 134 deciduous teeth, were recovered at tell leilan, syria, the site of a major urban center during the emergence of complex state society in northern mesopotamia in the mid-third millennium bc. tooth crown dimensions (faciolingual and mesiodistal diameters, total crown area, and molar crown area) are presented and the last two serve as the primary units of comparison for a diachronic interpretation of tooth size variation in the ancient near east. both permanent and deciduous dental data support the pattern of dental reduction since the middle paleolithic that has been documented for asia and europe. the total crown areas for the permanent and deciduous dental samples, 1189 mm2 and 497 mm2 respectively, place this archaeological population at the smaller end of the crown area scale for the near east; smaller in size than nearby paleolithic and neolithic populations. given the paucity of odontological data for this area, this study contributes to the odontometric history of mesopotamia and as a summary compilation and comparison of previously conducted odontometric work as it relates to the phenomenon of dental reduction within the ancient near east. dental anthropology 2003;16(3):73-80. 74 75 climate change that may have resulted from volcanic eruption and subsequent desertification of cultivable land in the region (weiss et al., 1993). this climate change has been documented in a number of areas in the eastern mediterranean (amiran, 1986; frumkin et al., 1991; otterman and starr, 1995; raban and galili, 1985), and has led some scholars to reevaluate previously held theories on the collapse of state-level societies in the ancient near east during the late third millennium bc (issar, 1995). the skeletal remains of 21 adults and 38 children were recovered during five seasons of excavation at tell leilan between 1979 and 1989 (weiss, 1985, 1986; weiss et al., 1993), and are presently curated at the department of anthropology, university of alberta. preservation of the skeletal remains is poor, although the dentition, when present, is in excellent condition. however, only 317 teeth out of a potential 672 permanent teeth and only 134 of a possible 760 deciduous teeth were collected during excavation. antemortem tooth loss probably contributed to the incomplete nature of the dental sample, as did difficulties in excavation; there are many neonatal and infant remains in which many of the deciduous teeth were either unformed or incompletely formed and hard to recover. fortunately, one or more tooth crown dimensions (e.g., mesiodistal and/or faciolingual crown diameter) could be measured in 82% of the collected permanent teeth and 60% of the deciduous teeth. the remaining teeth could not be measured due to incomplete eruption, extreme occlusal wear, or postmortem crown breakage. the majority of the remains from tell leilan date to the urban period of third millennium occupation (~2600 to ~2200 bc), although they range in date from the early third millennium bc to the early second millennium bc. due to the small sample sizes and relatively homogenous cultural context, however, all the remains are treated here as a sample from a single population. the senior author took tooth crown measurements with a helios needle-point dial caliper, calibrated to 0.05 mm. measurements were rounded to 0.1 mm. two measurements, maximum faciolingual (fl) diameter1 and maximum mesiodistal (md) diameter were taken for each tooth as described by mayhall (2000). intraobserver error was assessed by re-measurement of a randomly selected subset of 10% of the original sample, yielding a mean intraobserver measurement difference of 0.060 and a standard deviation of 0.22; such values are well within the ranges reported by other researchers for similar studies (wolpoff, 1971a; lukacs, 1985; lukacs and hemphill, 1991). paired sample t-tests were used to assess fl and md asymmetry of permanent right and left antimeres, although asymmetry was not evaluated for the deciduous sample because of its small size. tabulation and statistical analysis of the data were completed using excel (microsoft corporation, 1991) and systat software (systat inc., 1990-1992), respectively. the data are presented with the sexes pooled because the incomplete and fragmentary state of the skeletal remains rendered accurate assessment of sex for the tell leilan sample very difficult. crown area (ca) was calculated by multiplying the mesiodistal and faciolingual measurements for each tooth (wolpoff, 1971b). total crown area (tca), the sum of mean cross-sectional crown areas for all upper and lower teeth on one side of the jaw, and molar crown area (mca), the sum of the mean cross-sectional crown areas for upper and lower posterior teeth on one side of the jaw, serve as the primary units of comparison for diachronic interpretation of permanent tooth size variation in the ancient near east. tca and mca values for the comparative samples were obtained either from published data or were calculated from published mean md and fl crown diameters. results the mean differences between right and left measurements for each permanent tooth type were generated using a paired sample t-test. while there is a slight degree of directional asymmetry (with 11 of 16 teeth from the left side slightly larger, on average, than the right side), this difference is not statistically significant at alpha = 0.05. the standard deviation of mean differences between right and left antimeres provides another useful indicator of the extent of dental asymmetry (smith et al., 1982). in contrast to the pattern that is usually observed (lukacs and hemphill, 1991), the tell leilan standard deviation does not display a trend of smaller to larger values when moving distally within a given tooth class. this is most likely caused by the small number of paired observations as well as by the large standard deviation of certain teeth (e.g., third molars). the mean standard deviation of fl and md diameters for all teeth provides a general indication of asymmetry for the dentition as a whole (lukacs and hemphill, 1991); for the tell leilan permanent teeth, this value is 0.40, somewhat higher than that observed by other researchers (e.g. 0.23 and 0.24, lukacs and hemphill, 1991)2, although smith and co-workers (1982:283) have observed that standard deviations as large as 0.80 are not uncommon when samples of fewer than 100 individuals are used. crown diameters and areas are presented in tables 1 and 2 for the left side of the dental arcade, and, because of the statistically insignificant nature of leftright antimeric differences, values from the right side have been substituted for missing left values in order to increase the number of observations for certain teeth and, dentition from tell leilan, syria 1“faciolingual” is used here to encompass both labiolingual measurements of the anterior teeth and buccolingual measurements of the posterior teeth. 2this precludes the utilization of the mean standard deviation for the tell leilan permanent dentition in comparative analysis of interpopulational dental asymmetry. 74 75 thus, the utility of the statistical results. table 1 presents the mean fl and md crown diameters and crown areas for the tell leilan permanent dentition, sexes pooled. all measurements are in millimeters (mm) for crown diameters (fl and md) and millimeters squared (mm2) for crown areas (ca). table 2 presents the mean fl and md crown diameters and crown areas for both left and right antimeres in the deciduous dentition. numerous odontometric studies have utilized the tca and/or the mca for comparing tooth crown size variation (e.g., brace, 1980; lukacs, 1985; brace et al., 1987), since crown areas most closely approximate the total functional occlusal size of the dentition (wolpoff, 1971b). thus, crown area is the trait upon which natural selection acts (brace, 1980) making tca and mca, as single discrete values, highly useful for examining interpopulational variation in tooth size. for the present study, the total and molar crown areas of the tell leilan permanent dental sample are compared with the total and molar crown areas from several archaeological populations in the near east (fig. 1), beginning in the middle/upper paleolithic and ending in the iron age, as a rudimentary examination of tooth size reduction. although it would be preferable to limit the diachronic comparison to sites that are specifically located within northern mesopotamia, very few odontological studies have been conducted in the region. for this reason, crown area values for the nearest available archaeological populations in iran, iraq, israel, and turkey have been used instead. table 3 presents the data from sex-pooled samples for each archaeological population in the comparison. haddow and lovell table 1. mean crown diameters (in mm) and mean crown areas (in mm2) of permanent left teeth from tell leilan1 maxilla mandible faciolingual mesiodistal crown faciolingual mesiodistal crown diameter diameter area diameter diameter area n mean sd n mean sd mean sd n mean sd n mean sd mean sd i1 12 7.38 0.37 12 8.58 0.64 63.36 6.35 6 6.05 0.21 7 5.16 0.76 29.79 3.46 i2 11 6.77 0.60 11 6.46 0.42 43.94 6.44 10 6.36 0.37 11 5.48 0.76 33.99 4.82 c 10 8.63 0.46 10 7.30 0.45 64.02 5.13 9 7.92 0.53 10 6.71 0.37 52.60 3.83 p1 11 9.07 0.48 10 6.75 0.42 61.38 6.14 12 7.89 0.50 12 6.76 0.41 53.35 4.89 p2 11 9.07 0.66 11 6.53 0.43 59.43 7.81 12 8.04 0.81 12 7.03 0.62 58.69 10.46 m1 14 11.93 1.73 14 10.48 0.95 125.71 25.60 12 10.63 0.52 12 11.28 0.70 120.10 11.01 m2 11 10.85 1.07 10 9.49 1.10 103.59 19.04 11 10.43 0.47 12 11.22 0.80 115.57 11.01 m3 7 10.89 1.18 8 9.30 0.61 99.37 10.30 5 9.96 0.92 5 10.38 0.92 103.92 17.83 1since left-right antimeric differences are not statistically significant, values from the right side have been substituted for missing left values; n, number of observable teeth; sd, standard deviation table 2. mean crown diameters (in mm) and crown areas (in mm2) for deciduous teeth from tell leilan maxilla mandible faciolingual mesiodistal crown faciolingual mesiodistal crown diameter diameter area diameter diameter area side n mean sd mean sd mean sd n mean sd mean sd mean sd i1 r 2 5.25 0.21 6.75 0.07 35.45 1.06 4 4.28 0.93 4.58 0.79 20.05 7.43 l 2 5.25 0.21 6.70 0.14 35.15 0.64 3 3.87 0.50 4.37 0.81 17.13 5.39 i2 r 2 5.15 0.21 5.80 0.00 29.85 1.20 3 4.70 0.61 5.23 0.72 24.73 5.66 l 2 4.80 0 5.45 0.21 26.15 1.06 3 4.60 0.56 5.67 1.25 26.53 8.98 c r 3 5.97 0.65 6.73 0.86 40.53 9.43 4 5.70 0.28 6.03 0.15 34.35 2.01 l 4 6.20 0.29 6.95 0.19 43.13 3.20 3 5.80 0.20 5.93 0.15 34.43 1.67 m1 r 4 8.75 0.17 7.55 0.58 60.05 8.57 4 7.20 0.27 8.75 0.31 63.08 4.65 l 4 8.73 0.11 7.53 0.68 65.83 8.14 4 7.15 0.47 8.68 0.33 62.13 5.94 m2 r 4 9.85 0.66 9.53 0.17 93.75 4.72 4 8.73 0.15 10.53 0.29 91.80 1.55 l 4 10.00 0.39 9.73 0.33 98.28 5.19 4 8.88 0.26 10.55 0.29 93.60 2.67 76 77 with the exception of the tca of the modern european sample, which is provided by brace (1978), all tca and mca values were taken from the original mcas given for each tooth class, or were calculated from published md and fl crown diameters. in the case of the neanderthal sample from shanidar, crown areas for the anterior dentition could not be determined due to extreme occlusal wear (trinkhaus, 1978), and thus the mca serves as the primary comparative value. while the tell leilan crown diameters were recorded by measuring the maximum mesiodistal breadth for each tooth, it is not explicitly stated in a number of the odontological studies used for this comparison whether this same methodology was followed or whether the breadth between the mesial and distal contact facets of the molar teeth was measured in the manner of hrdlička (1924) and others. the latter technique may give smaller crown diameters, and hence smaller summed crown areas. values published elsewhere should thus be considered minimum estimates compared to the leilan data presented here. this must be taken into consideration when looking at the comparative data, although the size of the difference is likely to be small, on the order of 1 to 2 mm per tooth, based on the personal experience of the authors. as illustrated in table 3, the overall trend in permanent tooth size variation is one of gradual reduction over time, beginning in the middle/upper paleolithic with the skhul/qafzeh hominids and ending with the modern european population. the sample from chalcolithic alaca höyük in turkey does not follow this trend, however, having the smallest tca, smaller even than the modern european sample. many factors, including method of measurement and the biological affinities of the alaca höyük population may account for this difference. despite this, the overall dentition from tell leilan, syria fig. 1. map of the near east showing the sites used in the comparison of total and mean crown areas (table 3). no sites are shown for the natufian material, which dahlberg described only as being from ‘mesolithic palestine’ (dahlberg 1960:246). 76 77 trend is in accord with observations made by numerous researchers working in other regions of the world (e.g., brace, 1978; dahlberg, 1960, 1963; lukacs and hemphill, 1991; sofaer, 1973). if we examine the values from northern mesopotamia specifically (i.e., shanidar, jarmo, and tell leilan), it can be seen that a reduction in molar crown area of about 100 mm2 has taken place in the time span between the shanidar and jarmo samples (approx. 55,000 yrs), giving an average mca reduction rate of almost 0.002 mm2 per year. subsequently, the mca reduction between jarmo and tell leilan is about 10 mm2, over a span of approximately 4,500 yrs, giving an average mca reduction that is, also, about 0.002 mm2 per year. although additional research is needed, this evidence suggests that the rate of dental reduction does not seem to be linked to subsistence strategy. consistent with their fit in the widely recognized trend to dental reduction, the tell leilan data support the contention that upper central incisors and the first molars are considered genetically stable. these teeth resist variation in tooth size to a greater extent than do the more distal, i.e., later developing, teeth within their respective tooth class (dahlberg, 1963; sofaer, 1973) so that the extent of tooth size variation increases distally. the mca of the upper first molars exhibits a 3.2% difference from shanidar to tell leilan, as compared to a 28.8% change in the upper second molars. similarly, there is a 2.6% change in lower first molar size from the shanidar sample to the tell leilan sample, and a change of 15.5% in the lower second molars.3 further, the change is 2.4% for upper first molars and 11.5% for upper second molars when comparing tell leilan and the earlier agricultural sample from jarmo, and 0% and 4.5% change for lower first and second molars, respectively. by contrast to the case for permanent teeth, only a few studies have focused on the odontometry of the deciduous dentition (e.g., koenigswald, 1967; lukacs, 1981; lukacs et al., 1983; sciulli, 2001; smith, 1978). rarely have evolutionary trends in the deciduous dentition been documented, but smith (1978), lukacs and hemphill (1991) and sciulli (2001) have found that the rate of deciduous tooth size change is relatively stable within the past 5,000 to 10,000 years, roughly half that of permanent teeth (lukacs and hemphill, 1991). table 4 compares the tell leilan deciduous tca to smith’s (1978) data for several near eastern populations, from the epipaleolithic to modern times. it can be seen that, as with the permanent dentition, a distinct reduction trend can be observed over time. discussion many scholars have debated the mechanisms of dental reduction, but most agree that an overall reduction in tooth crown size should be observed in populations as they move from nomadic hunting and gathering subsistence modes to more sedentary agricultural modes (e.g., dahlberg, 1963; sofaer, 1973). indeed, studies have shown that the rate and extent of human dental reduction was at its most profound after the pleistocene, precisely the time period during which the transition in subsistence modes occurred (calcagno, 1989; macchiarelli and bondioli, 1986; reddy, 1992). haddow and lovell table 3. temporal variation in permanent tooth size among selected near eastern archaeological populations1 sample site cultural tca mca name location association (mm2) (mm2) source skhul israel middle paleolithic 1494 trinkaus, 1978 qafzeh israel middle paleolithic 780 vandermeersch, 1981 shanidar iraq upper paleolithic 773 trinkhaus, 1978 natufian palestine mesolithic 1272 722 dahlberg, 1960 jarmo iraq neolithic 1246 679 dahlberg, 1960 abou gosh israel neolithic 1240 685 aresnburg et al., 1978 tell leilan syria bronze age 1189 668 this study hasanlu iran iron age 605 rathbun, 1972 alaca höyük turkey chalcolithic 1161 643 senyürek, 1952 european various modern 1138 brace, 1978 1 tca, total crown area; mca, molar crown area 3crown areas were not available for the shanidar anterior teeth and thus cannot be compared with values for the tell leilan sample 78 79 although reduction in the size of the dentition occurred during the pleistocene, this reduction may be related to an overall reduction in body size or robusticity, especially in the masticatory apparatus and facial skeleton in general (macchiarelli and bondioli, 1986; brace et al., 1991). alternatively, selective pressures that favored larger or smaller teeth, depending on specific environmental conditions affecting dental health, may act as the primary mechanism of reduction (calcagno, 1989; calcagno and gibson, 1991). such conditions may have included dietary toughness and/or abrasiveness. early cultural advancements such as food preparation techniques (e.g., the use of fire to cook raw plant and animal foods), pottery, increasingly sophisticated tools, and changes in diet also may have played a role in selecting for smaller tooth sizes. given the paucity of odontological data for this area, however, it is not within the scope of this paper to determine the exact mechanisms of dental reduction for the region of northern mesopotamia. presently, there are no sources of modern near eastern odontometric studies suitable for comparative purposes. rosensweig and zilberman’s (1969) odontometric analysis of modern bedouin in israel did not include the third molars. thus, the tca for a modern european population (brace, 1978) is included in table 3 as an illustration of the extent of dental reduction since the middle paleolithic. studies of modern human populations have shown that the smallest tooth crown dimensions today are observable in europeans and certain asian populations (dahlberg, 1963; lukacs, 1985). some researchers have argued that this is because these regions were some of the earliest sites of sedentary agricultural development, and consequently have had the longest amount of time for dental reduction to occur (brace, 1978; reddy, 1992). because the region of mesopotamia is also one of the earliest sites of agricultural development, the same small tooth dimensions should be expected for modern near eastern populations. however, in all cases, extenuating factors such as genetic makeup, the migration of peoples and genetic drift will also play a role, the extent of which may be hard to determine at this time. what needs further investigation is that the rate of dental reduction appears to have remained constant through a transition from upper paleolithic hunting-foraging through the origins of food production and into the metal ages (data in table 3). this is, in fact, contrary to predictions of tooth size according to modes of subsistence, and may lend credence to explanations based on overall decreases in skeletal robusticity, which were more pronounced between the upper paleolithic and the neolithic than between the neolithic and the metal ages. conclusions results reported here of the metric analysis of the permanent and deciduous dentition of the northern mesopotamian bronze age site of tell leilan, when compared with odontometric data from varying periods within the near east, are consistent with the pattern of hominid dental size reduction observed worldwide since the middle paleolithic. the total crown areas (tca) for the tell leilan permanent and deciduous dental samples, 1189 mm2 and 497 mm2, respectively, place this archaeological population at the smaller end of the crown area scale for the near east; smaller in size than nearby paleolithic and neolithic populations, and slightly larger than more recent populations and the modern samples. the rate of reduction in hominid dentition has varied both spatially and temporally over the course of human evolution (e.g., calcagno, 1989; macchiarelli and bondioli, 1986; reddy, 1992), and factors such as genetic drift and the blending of geographically diverse populations over time often obscure or complicate our understanding of human dental reduction, especially in the post-paleolithic. it is hoped that larger dental samples from a wider variety of sites in ancient mesopotamia will eventually allow for a more detailed documentation of metric dental trends in this region and time period of the near east. acknowledgements we thank harvey weiss for making available the skeletal remains from tell leilan. financial support from the university of alberta (faculty of arts sas dentition from tell leilan, syria table 4. temporal variation in deciduous tooth size of selected near eastern populations1 cultural tca mca association n (mm2) n (mm2) source epipaleolithic 139 550 50 333 smith, 1978 neolithic 130 504 61 318 smith, 1978 chalcolithic 202 459 88 286 smith, 1978 middle bronze age ii 130 293 smith, 1978 bronze age (tell leilan) 35 497 16 319 this study iron age 509 474 smith, 1978 modern 212 454 smith, 1978 1 tca, total crown area; mca, molar crown area 78 79 fund, and the central research fund) and the social sciences and humanities research council of canada (standard research grant #410-95-0254) to nancy lovell, and from the university of alberta (faculty of arts and faculty of graduate studies and research) to scott haddow, is gratefully acknowledged. literature cited amiran r. 1986. the fall of the early bronze age ii city of arad. israel explor j 36:74-76. angel jl. 1968. appendix: human remains at karatas. am j archaeol 72:260-263. angel jl, bisel sc. 1986. health and stress in an early bronze age population. in: canby jv, porada e, ridgway bs, stech t, editors. ancient anatolia. madison: university of wisconsin press, p 12-30. arensburg b, smith p, yakar r. 1978. the human remains from abou gosh. in: lechevallier m, editor: abou gosh et 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third millennium bc. guildford: four quarters, p 1-6. weiss h, courty ma, wetterstrom w, guichard f, senior l, meadow r, curnow a. 1993. the genesis and collapse of third millennium north mesopotamian civilization. science 261:995-1004. wolpoff mh. 1971a. metric trends in hominid dental evolution. cleveland: case western reserve university, studies in anthropology, no. 2. wolpoff mh. 1971b. a functional measure of tooth size. southwest j anthropol 27:279-286. wooley cl. 1934. ur excavations vol. ii: the royal cemetery: a report on the predynastic and sargonid graves excavated between 1926 and 1931. new york: trustees of the two museums; carnegie corp. dentition from tell leilan, syria turner 1993b.4 pg7.jpg pg8.jpg pg9.jpg becker 1996.2 cucina et al. 1996.2 clarke 1993.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg kocsis and marcsik 1993.2 pg11.jpg pg12.jpg pg13.jpg pg14.jpg mcnamara 1997.5 pg19.jpg halbertstein 1993.3 pg8.jpg pg9.jpg pg10.jpg bollini et al. 2008.3 50 dental morphology has been used for determining biological and geographical affiliations. dental variation has a heritable component, seems to be caused by multiple genes, and is little influenced by environmental factors (rodríguez-florez et al., 2006). dental morphology can provide insights into phenotypic group differences, and these may be suggestive of differences in genotypic affiliation (varela and cocilovo, 2000). nonmetric dental traits seem to be controlled in part by genetics and are relatively free of sexand age-bias (scott and turner, 1997). the analysis of biological relatedness using dental nonmetric traits has been helpful even in commingled samples when standardized procedures are followed (ullinger et al., 2005). for these reasons, reconstruction of biological relationships among ancient human groups using teeth is an important research problem for south american bioarcheologists. the present study was carried out with a chubut human pre-conquest sample from patagonia, argentina, with the aim of exploring dental morphological dental patterns in this group (fig. 1). researchers describe the people of this region as a group of aboriginal populations named chonik or patagones del sur (tehuelches). these natives use an aboriginal dialect with “tchon” linguistic affiliation (canals frau, 1953). the objective of this article is to describe the presence of 40 dental nonmetric traits in this pre-conquest sample from the chubut. materials and methods pre-conquest human dental remains with reasonably reliable stratigraphic contexts are relatively rare from dental nonmetric traits in a pre-conquest sample from chubut region of patagonia, argentina gabriel a. bollini1, carlos david rodríguez-flórez2, and sonia e. colantonio3 1cátedra de antropología biológica ii, facultad de ciencias naturales, universidad nacional de la plata argentina 2grupo de investigaciones arqueodiversidad, universidad del valle – colombia, departamento de antropología y sociología, universidad de caldas colombia 3cátedra de antropología biológica y cultural, facultad de ciencias exactas, físicas y naturales, universidad nacional de córdoba – argentina, consejo nacional de investigaciones científicas y técnicas (conicet) correspondence to: carlos david rodríguez-flórez, grupo de investigaciones arqueodiversidad, universidad del valle colombiadepartamento de antropología y sociología, universidad de caldas colombia e-mail: bioarqueologia@ucaldas.edu.co abstract dental morphological trait expressions have been used in anthropology and forensic sciences for determination of biological and geographical affiliations. the present study was carried out with a chubut preconquest sample from patagonia, argentina. 18 skulls with partial dentitions from chubut (patagonia) were analyzed. the asu dental anthropology system was used to register the expression grade of all dental traits. in spite of small sample sizes, we can conclude that shovel shape (ui1, ui2), two lingual premolar cusps (up1, up2), and hypocone (um1, um2) frequencies suggest a mongoloid (sinodont) origin. dental anthropology 2008;21(2):50-53. argentina. marcellino and colantonio (2000) suggest a late period between 0 and 1,500 a.d for the present sample. the sample belongs to división de antropología del museo de ciencias naturales (la plata, argentina), and it is composed of 18 skulls with partial dentitions from chubut: 1041, 1057, 1060, 1081, e1837, 1083, 1117, 1119, 1165, 1167, 1837, 1067, e1844, 1139, 1167, 1140, 1047, cr (museum catalogue references). forty (40) dental nonmetric traits were recorded using the asu dental anthropology system to register the expression grade of all dental traits (turner et al., 1991). recording all of the dental traits was difficult because of environmental issues such as antemortem tooth loss, missing mandibles, postmortem fractures, and pathologies (fig. 2). consequently, a dichotomous recording system was used, grouping grade expressions into either “presence” (1) or “absence” (0). results trait frequencies are listed in table 1. it was impossible to adequately score three of the traits, namely paraconule (um1) and the entoconulid (lm1, lm2). values exceeding 70% were found for six traits—all in the upper arcade; these are shovel shape (ui1, ui2), two 51 fig. 2. upper arcade of a chubut skull (specimen 1083). lingual premolar cusps (up1, up2), and hypocone (um1, um2). traits with frequencies between 10 and 69% were found for 12 traits: shovel shape (li1, li2, uc, lc), double shovel (ui1, ui2), tuberculum dentale (ui1, ui2, uc), interruption groove (ui2), two lingual premolar cusps (lp2), and metaconulid (lm1). the remaining 19 traits did not occur in the sample: double shovel (uc, li1, li2, lc), tuberculum dentale (li1, li2, lc), interruption groove (ui1, li1, li2), two lingual premolar cusps (lp1), carabelli trait (um1, um2), paraconule (um2), metaconule (um1, um2), metaconulid (lm2), and protostylid (lm1, lm2). discussion for argentinean pre-conquest samples, previous studies by devoto and co-workers describe high frequencies of shovel shape in the maxillary incisors in early atacama indians (1968), pre-columbian tastilian indians (1971), and a northwestern argentinean group from salta province (1968). devoto describes shovel shape (ui1) in 13 specimens studied at 100%. the high prevalence of dental shoveling is considered a prime component of the mongoloid dental complex (hanihara, 1968). for devoto, in spite of his small samples, the data seem to be consistent enough to suggest that the specimens showed well-defined shovel-shaped maxillary incisors similar to well-typified mongoloid races (devoto, 1971). pre-conquest samples from tastil region have shown similar distributions of some non-metric dental traits as double shovel shape ui2 (0.10), and tuberculum dentale uc (0.31) (bollini et al., 2008). comparably, the sample of araucanos ethnic group exhibit similar distributions of shovel shape ui1 (0.85), and ui2 (0.71), double shovel shape ui1 (0.14), lingual cusp number up1 and up2 (1.00), hypocone um1 (0.83), and metaconulid (0.11) (bollini et al., 2007). these simple frequency comparisons are helpful in reinforcing the idea of early sinodontmongoloid ancestral groups in this region of argentina. the frequency of shoveling in the chubut sample studied here is near to these values, again suggesting a sinodont pattern. the use of morphological traits can involve problems of a methodological nature with small archeological samples. a necessary assumption is that dental trait expression is morphologically symmetrical between homologous teeth. in bioarcheology, estimating the frequency of a dental trait is influenced by the availability of samples due preservation, crown wear, and caries (rodriguez-florez and colantonio, 2007). some authors recommend scoring the higher grade of expression for each dental trait (turner and scott, 1977) or counting both the left and right sides for each individual (haeussler et al., 1988). the present investigation provides additional information for population dynamics that can help us infer the possible biological factors in the process of south american peopling into regional and temporal ranges on ancient patagonia, argentina (marcellino, 2002). acknowledgements we wish acknowledge to cecilia ferreira by helping in recording and laboratory assistance. this article is in memory of dr. jorge eduardo bollini (r.i.p.); see key references (bollini et al. 2006, 2007, 2008). references cited bollini ga, rodríguez-flórez cd, colantonio se, mendez mg. 2006. antropología dental de una serie prehistórica de araucanos provenientes de la patagonia argentina. revista de arqueología fig. 1. map of the chubut region of argentina.. chubut dentition, patagonia 52 tooth type trait dichotomy presence absence k/n frequency maxillary dentition ui1 shovel shape 0 3 1 3 0 10/11 0.90 double shovel 0 4 1 4 0 3/11 0.27 tuberculum dentale 0 3 1 3 0 4/11 0.36 interruption groove 0 1 1 0 0/11 0.00 ui2 shovel shape 0 3 1 3 0 9/10 0.90 double shovel 0 4 1 4 0 1/9 0.11 tuberculum dentale 0 3 1 3 0 4/10 0.40 interruption groove 0 1 1 0 2/11 0.18 uc shovel shape 0 3 1 3 0 3/7 0.42 double shovel 0 4 1 4 0 0/10 0.00 tuberculum dentale 0 3 1 3 0 2/10 0.20 up1 lingual cusp number 1 3 2 3 1 11/11 1.00 up2 lingual cusp number 1 3 2 3 1 9/9 1.00 um1 hypocone 0 3 1 3 0 7/7 1.00 carabelli complex 0 4 1 4 0 0/7 0.00 paraconule 0 1 1 0 -/ metaconule 0 1 1 0 0/1 0.00 um2 hypocone 0 3 1 3 0 10/10 1.00 carabelli complex 0 4 1 4 0 0/9 0.00 paraconule 0 1 1 0 0/4 0.00 metaconule 0 1 1 0 0/6 0.00 mandibular dentition li1 shovel shape 0 3 1 3 0 1/6 0.16 double shovel 0 4 1 4 0 0/6 0.00 tuberculum dentale 0 3 1 3 0 0/6 0.00 interruption groove 0 1 1 0 0/6 0.00 li2 shovel shape 0 3 1 3 0 3/8 0.37 double shovel 0 4 1 4 0 0/7 0.00 tuberculum dentale 0 3 1 3 0 0/7 0.00 interruption groove 0 1 1 0 0/8 0.00 lc shovel shape 0 3 1 3 0 2/7 0.28 double shovel 0 4 1 4 0 0/9 0.00 tuberculum dentale 0 3 1 3 0 0/9 0.00 lp1 lingual cusp number 0 3 1 3 0 0/8 0.00 lp2 lingual cusp number 0 3 1 3 0 4/8 0.50 lm1 entoconulid 0 1 1 0 -/ metaconulid 0 1 1 0 1/4 0.25 protostylid 0 1 1 0 0/10 0.00 lm2 entoconulid 0 1 1 0 -/ metaconulid 0 1 1 0 0/2 0.00 protostylid 0 1 1 0 0/9 0.00 table 1. dental nonmetric frequencies in the sample g.a. bollini et al. 53 americana. instituto panamericano de geografía e historia (mexico) 23:385-406. bollini ga, rodríguez-flórez cd, colantonio se, mendez mg. 2007. morfología dental de una serie prehistórica de araucanos provenientes de la patagonia argentina y su relación biológica con otras poblaciones prehistóricas argentinas y del mundo. int j morphology, sociedad chilena de anatomía (chile) 24:705-712. bollini ga, rodríguez-flórez cd, colantonio se. 2008 dental non-metric traits in a pre-conquest sample from tastil region in argentina, south america. bull int assoc paleodont 2:19-25. canals frau s. las poblaciones indígenas de la argentina. editorial hyspamerica, 1953. devoto fch 1971. shovel-shaped incisors in precolumbian tastilian indians. j dent res 50:168. devoto fch, arias nh, ringuelet s, and palma nh. 1968. shovel-shaped incisors in a northwertern argentinean population. j dent res 47:820-823. haeussler am, turner cg ii, irish jd. 1988. concordance of american and soviet methods in dental anthropology. am j phys anthropol 75:218. hanihara k. 1968. mongoloid dental complex in the permanent dentition. proc. viiith internat congress anthropol ethnol sci i:293-300. marcellino aj, colantonio se. 2000. los cráneos aborígenes más antiguos de la argentina: un ensayo clasificatorio. tendencias actuales de la investigación en la antropología física española p 205-218. marcellino aj. 2002. los procesos de adaptación en el poblamiento aborigen de sudamérica. anales de la academia nacional de ciencias de buenos aires, p 9-26. rodriguea-florez cd, colantonio se. 2007. bilateral asymmetry of upper permanent dentition in six archaeological pre-conquest samples from colombia, south america. dental anthropology 20:14-18. rodriguez-florez cd, fonseca gm, villalba mt. 2006. brief communication: occurrence of an eighth cusp on primary second mandibular molars of a contemporary argentinean child. dental anthropology 19:73-75. scott gr, turner cg ii. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. turner cg ii, scott gr. 1977. the dentition of easter islanders. in: dahlberg aa, graber tm, editors. orofacial growth and development. the hague: mouton, p. 229-249. turner ii cg, nichol cr, scott gr 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss inc., p 13-31. ullinger jr, sheridan sg, hawkey de, turner ii cg, cooley r. 2005. bioarchaeological analysis of cultural transition in the southern levant using dental nonmetric traits. am j phys anthropol 128:466-476. varela hh, cocilovo ja. 2000. structure of the prehistoric population of san pedro de atacama. curr anthropol 41:125-132. chubut dentition, patagonia zhou and corruccini 1997.2 pg3.jpg pg4.jpg pg5.jpg harris and sjovold 2004.5 82 83 dental anthropologists commonly use morphological data to estimate the degree of dissimilarity among samples—so-called biological distance or phenetic distance. it is supposed that the greater the dissimilarity between two samples, the less the genetic contact between the groups due to separation by time and/or space. an issue of some interest is how, statistically, to quantify the degree of dissimilarity among groups in an objective manner. despite the numerous methods suggested in the literature (reviewed in constandsewestermann, 1972), dental anthropologists have focused almost exclusively on the use of cedric a. b. smith’s mean measure of divergence (mmd). our experience is, however, that there are misunderstandings about the mmd. there seems to be no commercially available computer program to calculate mmd, which would promote consistency, and the purported formula for mmd (if reported at all) differs among authors (including the repeated publication of statistical errors). the purpose of this note is to clarify the calculation of mmd in a simple, intentionally nontechnical manner. overview constandse-westermann (1972) and, in particular, sjøvold (1973, 1977) provide detailed descriptions of the development and use of the mmd. in brief, the british statistician cedric a. b. smith devised this statistic for m. s. grewal (1962) who used it to estimate the biological divergences that had developed across generations in sublines of the common c57bl strain of laboratory mice. grewal calculated trait frequencies for calculation of smith’s mean measure of divergence for intergroup comparisons using nonmetric data edward f. harris1* and torstein sjøvold2 1college of dentistry, university of tennessee, memphis 2stockholm university, stockholm, sweden abstract: the mean measure of divergence (mmd) is a formula that converts a battery of trait frequencies into a numerical value such that the more dissimilar two samples are, the greater the value. this measure of phenetic distance was developed by the statistician cedric a. b. smith and has become popular among dental anthropologists and osteologists for estimating the dissimilarity among groups in order to help reconstruct populations’ movements and structure over time and space. the purpose of the present study is to present the correct formulae and procedures for the mmd given that (1) numerous errors have entered into the literature concerning the formulae themselves, (2) improvements have been described that should be incorporated, and (3) various misunderstandings and misinterpretations have developed that need clarification. dental anthropology 2004;17(3):83-93. 27 cranioskeletal bony variants such as the occurrence of foramina, accessory sutures, and bony processes (traits primarily described by grüneberg, 1950 and by deol, 1955). it was supposed that the sublines diverged with time due to latent heterozygosity in the inbred line but, primarily, from the accumulation of mutations distinct to each subline—which is why the term divergence is used for this phenetic measure rather than distance. the mmd subsequently was popularized in anthropological circles by a. c. berry and r. j. berry, notably in their nonmetic skeletal comparisons among human groups (e.g., berry and berry, 1967; berry, 1968; berry, 1974, 1976; and elsewhere). this pair of authors promoted the use of “minor skeletal variants” as epigenetic features that, from their analyses, had a genetic basis but were essentially independent of age and sex and size of the individual. these minor skeletodental variants, such as the presence of nutrient foramina and accessory molar cusps, can each be viewed as a dichotomous feature, so summary of a sample is easily expressed as a trait frequency—and smith’s mmd provides a method of estimating the phenetic distances among samples arrayed through space and/or time. smith’s original formula as described by grewal (1962) is *correspondence to: edward harris, department of orthodontics, college of dentistry, university of tennessee, memphis, tennessee 38163 usa. e-mail: eharris@utmem.edu 84 85 mmd r 1 n 1 n ik jk 2 k 1 r i j = −( ) − +         = ∑ θ θ [eq. 1] that is, the difference between samples i and j for the frequencies of trait k is calculated and then this difference is squared so that positive and negative differences do not cancel one another. the sum of the differences is divided by r, the number of traits used in the equation, in order to generate the “mean” or average difference between samples i and j. the correction term 1/n i +1/n j then is subtracted from this average to correct for sampling fluctuations. grewal (1962:229-230) actually described the mmd in the text of his paper rather than presenting eq. 1, which led to misinterpretations by other researchers. it follows from this equation that the “size” of a mmd depends on the battery of traits used, and mmds generated from different sets of variables are not comparable, even for the same pair of groups. these conditions hold for all measures of “biological distance” (sokal and sneath, 1963; constandse-westermann, 1972; reyment, 1991). while it is not our purpose to critique the merits of the mmd, one noteworthy issue is that it does not account for intertrait correlations, which commonly is viewed as a shortcoming. intertrait associations (“correlated traits”) inflate the mmd because correlated traits share some of the same informational content, and this shared (redundant) information increases with the strength of the correlation. for example, the occurrence of incisor lingual shoveling (hrdlička, 1920, 1922) is strongly intercorrelated on the maxillary central and lateral incisors (and between homologous teeth in the two quadrants), so including trait frequencies of shoveling on both ui1 and ui2 carries a lot of statistically redundant information. studies have disclosed that nonmetric intertrait associations are more common than expected by chance (e.g., corruccini, 1974; scott, 1977, 1978, 1979). on the other hand, constandse-westermann (1972) points out that, within an analysis, the same suite of traits is used for all of the pairwise comparisons so that, insofar as intertrait associations are a species-wide phenomenon, the effect of statistical redundancies can be viewed as a constant across the study. statistically significant intertrait correlations may also occur by chance. at the conventional alpha level of 0.05, one expects to make a type i error (i.e., reject a true null hypothesis) 5% of the time. suppose that a battery of 30 morphological traits is scored (table 1). one would expect that 21 of the matrix of 435 pairwise correlations would be statistically significant due to chance alone. an associated issue is that the ability to detect statistically significant differences depends on the available sample size (degrees of freedom) available (e.g., fisher and van belle, 1993). biologically real but weak correlations generally cannot be detected with small sample sizes. statistical textbooks deal with the subject in much more detail, but guidelines for detecting biologically real intertrait correlations are (1) comparable correlations should appear in the analyses of multiple samples and (2) correlations found in larger samples, where effects of sampling fluctuations are dampened, generally are more reliable. weak associations, particularly with the sample sizes normally encountered in anthropological studies, will not seriously distort mmd results. frequency transformations the mmd was devised to deal with percentages of dichotomous data (also termed nonmetric or, occasionally, discontinuous traits). this is in contrast to quantitative (interval and ratio scale) data where more common statistical methods can be employed, such as pearson’s (1926) virtually-defunct coefficient of racial likeness, penrose’s formulae (1953) for distance, size and shape (where distance = size + shape), and the current gold-standard, mahalanobis’ d2 (mahalanobis, 1936). qualitative data, like the frequency of the dryopithecus y-5 pattern on a lower molar (hellman, 1928), generally are converted to percentages, commonly termed trait frequencies. such data either are scored as dichotomous traits or a “cut-point” is decided upon along an ordinal grading scheme to create dichotomous traits. formally, the sample frequency of a trait can be expressed as p (and the frequency of absence as q) such that p + q = 1 and p = 1 – q. this simply relates to the binomial distribution. the sample variance of this distribution is pq/n (e.g., sokal and rohlf, 1995: 419), where p and q are the frequencies of trait presence and trait absence, respectively, and n is the sample size. for a given sample size, the sample variance is tied to the frequencies of p and q. the degree of distortion (that is, the changing value of the variance through the frequency distribution from zero to one) increases as the sample size decreases (fig. 1). this nonlinear association between the variance and the trait frequency number of number of number expected traits correlations from chance 5 10 1 10 45 2 20 190 9 30 435 21 40 780 39 50 1,225 61 table 1. number of statistically significant pairwise associations expected in variously-sized batteries of traits e.f. harris and t. sjøvold 84 85 � �� � �� � �� � �� � �� � �� � �� � �� � �� � �� � �� ����� ����� ����� ����� ����� ����� � � � � �� �� � �� � � �� ��������������������� ������ ������ ������ ������� ������� is obvious in the range of most anthropological samples—either of living or skeletal specimens. an appropriate transformation of the percentages diminishes this association between a trait frequency and its variance, making the variance more stable. historically, the transformation can be as simple as sin-1√p (fisher, 1958), but other choices work much better. the arcsine (or “arcsin” or “inverse sine”) transformation is a trigonometric function, generally coded as sin-1, and it can be expressed either in degrees or radians. (the arcsine function sin-1(x) is in no way related to 1/sin(x) as might be guessed.) transforming trait frequencies introduces an issue that has not been appreciated universally when calculating mmds. if a researcher uses a familiar transformation—such as sin-1√p (fisher, 1958)—with the units in degrees, then the sampling variance of this value is 820.7/n (constandse-westermann, 1972:118; sjøvold, 1973:208). historically, this value was cumbersome when manually calculating the mmd. instead, the convention has been to express the transformation in radians rather than percentages, but, as smith (1972: 242-244) illustrates, the results are mathematically identical. radians are a trigonometric device that simplify many calculations. several deterministic equalities between degrees and radians can be noted, such as π radians = 180° 2π radians = 360° 1 radian = 180 180 3 14159 57 17 75 ° ≈ ° ≈ ° ′ π . . for present purposes, radians are desirable because the transformed frequencies of sin-1√p have the simpleto-compute variance of about 1/4n, where n is the sample size. the point needs to be emphasized that radians rather than degrees are to be used unless one also incorporates the appropriate variance correction into the mmd equation. grewal’s (1962) transformation of p is sin-1(1-2p), and its variance is 4 times as large as that for fisher ’s transformation, namely 1/n (because 4 times 1/4n = 1/n), when both are expressed in the same units, either degrees or radians. green and suchey (1976) compared some published frequency transformations and concluded that the formula suggested by freeman and tukey (1950) did a decidedly better job of stabilizing the variance than grewal’s sin-1(1-2p) transformation. the freemantukey transformation is θ = − + +     1 2 arcsin(1 2m n 1 ) 1 2 arcsin 1-2 m+1 n+1     [eq. 2] where m is the number of occurrences of the trait in the sample and n is the number of scorable specimens in the sample so the trait frequency is p = m/n. θ is computed for the kth trait in sample i and likewise for sample j, then these two values are entered into eq. 1. this means that the raw counts (m and n) are needed to calculate the mmd, not the trait frequencies. graphs of these three arcsine transformations of the trait frequency are shown in figure 2. in practice, there is very little improvement with the freeman-tukey transformation compared to another transformation proposed by anscombe (1948), namely θ = sin 1-2 m+ 3 8 n+ 3 4 -1                       [eq. 3] indeed, according to the graphical comparisons in green and suchey (1976:63), anscombe’s transformation is slightly better than the freeman-tukey formula at asymptotically stabilizing sampling variance. both fig. 1. examples of how the variance of the trait frequency p changes depending on sample size. in all cases, sample variance is at its maximum when p = q = 0.5, but the range of values diminishes as sample size increases. mean measure of divergence 86 87 ���� ���� ���� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� � �� � �� � �� � �� � � �� � �� � � �� � � ��������������� are clear-cut improvements over grewal’s transformation in terms of stabilizing the variances of the binomial variable. we suggest that anscombe transformation is preferrable for a couple of reasons. historically, rao (1952) recommended anscombe’s transformation when sample sizes are moderately large. this transformation also has the advantage that it can be rewritten as a single arcsine: sin n n+ 3 4 1-2p-1           ( ) [eq. 4] or, equivalently, fig. 2. graphs of the arcsine transformations of trait frequency p discussed here, namely (1) fisher’s sin-1√p, (2) grewal’s sin-1(1-2p), (3) the freeman-tukey transformation shown in eq. 2, and (4) the anscombe’s transformation shown in eq. 3. sjøvold (1977) has shown that these latter two transformations are mathematically very similar— which is why they are superimposed here throughout their ranges. e.f. harris and t. sjøvold freeman-tukey and anscombe grewal fisher 86 87 sin 1 1+ 3 4 n 1-2p-1                 ( ) [eq. 5] the freeman-tukey transformation is quite complicated by comparison. moreover, anscombe’s formula can be extended to multistate traits (in contrast to dichotomous traits)—though we do not discuss that option in this paper—and this is not true of the freeman-tukey formula. adjusting for variances smith’s mmd originally was published without explicit directions (grewal, 1962), then ambiguously by berry and berry (1967:370), and then incorrectly by berry (1968:115). these shortcomings created a rocky start for the mmd, generating errors that occasionally reappear. constandse-westermann (1972: 119) was the first to explicitly publicize this formula: mmd 1 n 1 n r ik jk 2 ik jkk 1 r = −( ) − +        = ∑ θ θ [eq. 6] though knowing what the equation should be makes the description by grewal (1962:229-230) clear. notice that in eq. 6 the correction term applies to each variable, not just the summary value as indicated in eq. 1. the quantity(1/n ik +1/n jk ) is subtracted from the squared difference of trait frequencies to adjust for the mathematical properties of the squared differences between the theta values (θ) that overestimate the divergence between the corresponding populations. that is, 1/n ik +1/n jk is the variance of the two angular values. these theoretical and observed distributions coincide more closely as n increases. n ik and n jk are the sample sizes for the kth trait so that, depending on how fragmentary the dental or skeletal data are, the usable (scorable) sample sizes will vary from trait to trait. notice too that the correction term in eq. 6 has the subscript k that was absent in eq. 1. equation 1 assumes that the data are complete, so sample sizes are identical across the whole suite of traits. this commonly is not the case because of damaged skeletal elements or attrition, caries, or loss of teeth. if there are missing data, sample size needs to be subscripted so it can vary by trait. green and suchey (1976) and green et al. (1979) note that this conventional correction formula overestimates the true variance and that, instead, the correction term (attributable to freeman and tukey, 1950) should be 1 n 1 2 1 n 1 2ik jk + + + [eq. 7] square-root transformation if one reviews the various publications using the mmd, it will be seen that a square-root transformation crept into the formula with time. for example, a. c. berry (1974:348) reports the formula to be: mmd= 1 n + 1 n r ik jk 2 ik jkk=1 r θ θ( )        ∑ [eq. 8] this square-root modification is due to r. j. berry (1969), and we suggest a couple of reasons for this addition. the square-root modification may be supposed to be an improvement towards the goal of “triangular equality” among the mmds. given three groups, say a, b and c, the squared distance between two groups (say a and b) could be greater than the sum of the squared distances between the other two pairs, so ab > (bc + ac). this actually is not true. the actual effect of the square-root transformation is to change the reference space from cartesian space to a sphere, which creates mathematical problems (sjøvold, 1977). even though the square root modification (eq. 8) is commonly encountered, it stems from a misunderstanding, and we strongly suggest that it not be used. alternatively, the square-root modification may have been perceived as a “correction” for estimating a squared divergence, so taking the square root would estimate the unsquared (linear) divergence. analogously, other researchers have used the squareroot of mahalanobis’ d2, supposing that d is a more relevant measure of intergroup distance than d2. the modification is unwarranted, though, because the mmd (eq. 6) is an unbiased estimated of the squared divergence between the populations from which the samples were drawn, but mmd is not an unbiased estimated of the unsquared divergence (sjøvold, 1977: 46). consider too that the mmd commonly is less than 1.0, so mmd will be larger than mmd. artificially increasing mmd by using the squareroot transformations makes the test of significance (discussed below) inappropriate because the mmd are inflated values, so it is (falsely) harder to achieve statistical significance if it is not understood that the mmd and not the mmd needs to be tested. mean measure of divergence 88 89 sample size a tangential issue is how to score fragmentary data, particularly dental traits that typically occur bilaterally (e.g., turner et al., 1991). incompletely preserved skeletodental data, where the left and right occurrences of a trait cannot always be determined, is a common problem in archeological samples, but the same issue arises with living specimens when the dentition is compromised by caries, attrition, dental restorations, extractions and other causes of tooth loss. green et al. (1979) reviewed the options for scoring incomplete data, concluding that the least biased method is to consider both left and right sides and calculate the trait frequency as the number of times the feature occurs on either side divided by the number of scorable sides. this maximizes the amount of usable information without artificially inflating sample sizes by using sides instead of individuals as the unit of study. it does assume that there is no systematic side preference in trait frequencies, which seems to be the case in the main. a related issue of sample size becomes obvious from inspection of eq. 6. if the sample size for a trait is small in one or both samples being compared, then the adjustment factor can be as large or larger than the phenetic difference that is measured as (θ ik -θ jk )2. this leads to a mmd that is zero or negative, but not because of the similarity in trait frequencies but because of small sample sizes. that is, the adjustment—which is wholly a function of sample sizes—can readily overwhelm the biological measure of difference (θ ik θ jk )2, so mmd may well be “controlled” by inadequate sample sizes when dealing with samples in the range typically encountered in anthropological collections. this artifactual effect of diminutive sample sizes can easily pervade an analysis for several reasons. one, the mmd almost invariably has been applied within a species, so the range of trait frequencies (and, thereby, differences between groups) is not great. berry and berry (e.g., 1967) argued that discrete skeletodental traits exhibit considerable differences in frequencies among groups, but this has not been substantiated in the dental anthropological literature (e.g., lasker and lee, 1957; scott and turner, 1997). bigger between-group differences in trait frequencies obviously can “offset” the reductionist effect of small sample sizes. two, sample sizes generally are comparable for the whole suite of traits in a sample; there is little chance of small sample sizes for some traits being offset by substantially larger samples of other traits. three, when sample sizes are small visà-vis the phenetic difference (θ ik -θ jk )2, the adjustment produces a negative distance for that trait, but it seems that researchers have simply averaged this negative value into the mmd. in fact, a negative value for a trait has no biological meaning; it is wholly an artifact of the frequencies being too similar and/or the samples sizes being too small. negative distances consider the largest possible difference between a pair of trait frequencies. suppose, hypothetically, e.f. harris and t. sjøvold sample correction size term 10 0.040 15 0.018 20 0.010 25 0.006 30 0.004 40 0.003 50 0.002 75 7x10-4 100 4x10-4 table 2. representative sample sizes and associated correction term1 1sample size is the scorable number of individuals per group and assumes n i = n j . fig. 3. graph of the correspondence between the difference in trait frequencies in a pair of samples and the squared difference (θ ik -θ jk )2 using grewal’s transformation. � � � � � � � � � � �� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� ��� � � � � �� � �� �� �� �� � �� �� �� � �� � �� � �� � �� � � ������������������������������� 88 89 � �� �� �� �� ��� ��� ��� ��� ��� ��� � �� � �� � �� � �� � �� � �� � �� � �� � �� � �� � �� � � � � �� �� �� � �� �� �� � � ������������������������������� that a trait like the three-rooted mandibular first molar (tratman, 1938) is virtually fixed at 99.99% in group i but is quite rare, 0.01%, in group j. this squared difference (θ ik -θ jk )2 using grewal’s arcsine transformation is 9.62. all other between-group comparisons other than this extreme will be less than 9.62. obviously, too, as trait frequencies approach each another in two samples—as occurs when groups are genetically and phenotypically more similar—the smaller the (θ ik -θ jk )2 difference will be and the greater the relative influence of the correction term. we can look at some simple examples to guage the influence of the correction term (table 2). the relationship is linear. when sample sizes are less than about 20 (per sample, assuming n i = n j ), the term is fairly large, in excess of 0.10. if sample sizes are 50, the term is 0.002, and if sample sizes are 100, the term is just 0.0004. these values can be compared to those generated by the squared differences of the transformed frequencies (θ ik -θ jk )2 as shown in figure 3. there is a negative hyperbolic relationship here. as examples, when the difference in trait frequency is 0.85, the contribution to the mmd will be 4; when the difference is 0.65, the contribution will be 2; and when the difference is 0.48 the difference will be 1. figure 4 graphs these two opposing values, namely the squared difference in trait frequencies (θ ik -θ jk )2 on the x axis and the sample size (per group) at which this difference is nullified by the correction factor. we see that sample size (per group) can be less than 20 and there will still be a positive contribution to the mmd so long as trait frequencies differ by at least 15 percentage points. if the difference in frequencies is just 10 points, then sample sizes less than 40 will generate a negative md for that trait. if the difference is just 5 percentage points, sample sizes need to be at least 200 per group. this graph should provide some helpful guidelines when the researcher is deciding which skeletodental traits possess enough intergroup variation to generate meaningful mmds. one can see that the potential magnitude of an mmd is limited; the lower limit is zero and the upper limit is less than about 9.6. this upper limit assumes that the sample sizes of the two groups are very large (so the correction factor is effectively nil) and that the trait frequencies between groups are as different as possible for all traits considered. in practice, actual values for the mmd will be far smaller than this. because the obtained mmd values are small (generally below 0.50), some researchers have multiplied them by 100 or 1,000 for presentation, and this has led to misunderstanding when the research report was not adequately scrutinized by subsequent investigators. test of significance two groups can have a nonzero mmd simply due to chance deviations because we are dealing with finite samples of specimens, not statistical populations. this might make a test of statistical significance useful. the smaller a group’s sample sizes, the more the mmd can differ from zero due to sampling fluctuations that do not represent a “true” biological difference. c. a. b. smith developed a test of statistical significance for the mmd based on its variance, though, like the distance formula itself, several early publications contain errors. constandse-westermann (1972:120) lists the correct formulation of the variance of mmd: 4 1 n 1 n r 1 n 1 n ik jk 2 ik jk +         −( ) − +     θ θik jk            = ∑ k r 1 r2 [eq. 9] to be clear, the standard deviation of this variance is the square root of eq. 9, namely mean measure of divergence fig. 4. graph showing where the difference in trait frequencies (x axis) equals the correction term (y axis) that is a function of sample sizes. 90 91 4 1 n 1 n r 1 n 1 n ik jk 2 ik jk +         −( ) − +     θ θik jk            = ∑ k r 1 r2 [eq. 10] sjøvold (1973:210; 1977:30; also see green and suchey, 1976:67) notes that, under the null hypothesis, the variance simplifies to 2 r 1 n 1 n2 ik jk +        = ∑ k r 1 2 [eq. 11] so the square root of eq. 11 is the standard deviation of mmd 2 r 1 n 1 n2 ik jk +        = ∑ k r 1 2 [eq. 12] standard statistical theory indicates that two samples will differ significantly at alpha = 0.05 when their means differ by at least 1.96 their standard deviation. this value of 1.96 rounds to 2, which is where the statements come from (e.g., sjøvold, 1973:216; green and suchey, 1976:67) that the null hypothesis of “no difference” can be rejected when the mmd is more than twice its standard deviation (eq. 12). this rule of thumb is, however, a rough estimate, particularly if the usable sample sizes vary much among the traits used. there are, however, at least three considerations that detract from the value of testing the statistical significance of mmd: one, the meaning of a “significant” difference is quite vague biologically. this relates to group selection; if two samples are sufficiently different on the basis of geography, anthropology (i.e., race, language, and culture), or distance, then they already characterize separate populations, and no test is required. if, as occurs too frequently in the anthropological literature, samples differ in time, then of course they constitute samples of different populations because a biological population (mayr, 1963:136) is a community of potentially interbreeding individuals at a given locality. all members of a local population share in a single gene pool, and such a population may be defined also as a group of individuals so situated that any two of them have equal probability of mating with each other and producing offspring…. this is where the oxymoron of a “skeletal population” is seen to be absurd (cadien et al., 1974). it might be countered that the aim is to see whether two samples are so similar that they can be considered to be drawn fro the same statistical population. smith (1972:243) notes that, “alas, this seems to confuse the ideas and uses of a ‘distance’ and a ‘test of significance’. also, it is usually a nonsensical question, for two distinct populations are distinct, and are not in any reasonable way samples from a single population.” moreover, there are more appropriate and more efficient statistical methods for testing the differences in trait frequencies than the averaged result given by the mmd (see, e.g., fleiss, 1981; sokal and rohlf, 1995). two, “the crucial point in every problem concerning biological divergence or distance—and in fact for the study of biological distance in general as well—is the choice of variables of a given set to use” (sjøvold, 1977:31). the issue here is that the size of the mmd between pairs of samples can be increased or diminished simply by varying the traits used. this issue has been reviewed in depth in books on numerical taxonomy because trait selection—which traits and how many traits—is so central to the results obtained (e.g., sokal and sneath, 1963; reyment, 1991). the issue revolves on two considerations (see sjøvold, 1977:31), one is whether the chosen trait frequencies are sufficiently different among the groups while still being representative of the groups and, two, whether intergroup divergence is diminished or accentuated by the traits selected in the prior consideration. those familiar with population differences in dental trait frequencies (reviewed in turner et al., 1991; hillson, 1996; scott and turner, 1997) will appreciate that different traits discriminate between different groups; important discriminators for one comparison are noncontributory in other comparisons. the “best” discriminators depend wholly on the groups being compared. put simply, the quantitative results from the mmd (and other distance statistics) are prone to researchers’ biases in trait selection. a test of statistical significance is, then, of little practical use. the researcher needs to be aware of the influence of trait selection and be prepared to defend the suite of traits used for an analysis. the simple inclusion of “lots” of dental traits actually is counterproductive because most do not differ sufficiently among groups or, like the paramolar tubercle of bolk (dahlberg, 1945) or the uto-aztecan premolar (morris et al., 1978), occur too infrequently to contribute numerically to a mmd. sjøvold (1973:211) also makes the point that “dummy” variables are not to be used; these are traits that are fixed across all of the samples studied (either always present or always absent). sjøvold recommends the use of bartlett’s adjustment (bartlett, 1936) when the trait frequency is fixed in a given sample: if the trait does not occur in a sample (p = 0) then it should be replaced by p = 1/4n. if the trait always occurs (p = 1) then it should be replaced by p = 1 (1/4n). green and suchey (1976) also promote the use of bartlett’s adjustment to help correct for exe.f. harris and t. sjøvold 90 91 treme trait frequencies. trait selection the mmd necessitates some care in trait selection in order to preserve its statistical properties. this can present a perceptual conflict with the goals of numerical taxonomy. on the one hand, long-held goals in numerical taxonomy are repeatability and objectivity. a matrix of mmds should not depend on the traits selected; instead, a goal is that different researchers, using different sets of traits should arrive at a comparable set of intergroup relationships. an obvious and attractive way of seeking this goal is to use many variables, without selection, so the resulting mmds will constitute a broad, comprehensive consensus of how the groups are related phenetically. sokal and sneath put forth the seldom-achieved suggestion that, “at least sixty [traits] seem desirable, and less than forty should never be used” (1963:51). the idea is that many traits will more-thoroughly sample the battery of available or possible traits, thus diminishing the influence of any one or a few traits, and similarly will guard against biases in trait selection, thus making the phenetic distances more objective. the statistical problem with this approach is that some—perhaps several or, even, most—traits will be nondiscriminatory among the groups. as seen from eq. 6, when there is little or no difference in trait frequency among the groups, the contribution of that trait to the mmd will not be zero. instead, because of the correction factor, the trait’s contribution will be negative, which has no biological meaning. and, obviously, intergroup differences in trait frequencies need to be larger to be contributory when sample sizes are smaller. an obvious solution to the accumulation of negative values in the calculation of an mmd would simply be to set the negative values to zero on a trait-by-trait basis. this, however, creates another problem, so it is not recommended. when mmds are calculated as in eq. 6, they are unbiased estimates of the underlying population differences. this feature is lost—and with it several statistical properties—if negative contributions are set to zero. if negative values are set to zero, the mmds will over-estimate the population differences. instead, we recommend the following two-step approach: one, a priori a scientist should propose to use as large a battery of traits as feasible, thereby seeking the goals of repeatability and objectivity set forth by sokal and sneath (1963). this initial list needs to be made explicit in the publication; it may well supply important information for other researchers following up with later studies. however, these proposed traits need to be tested to see which ones contain contributory information, which we define as a trait showing a statistically significant difference between at least one pair of the groups being evaluated. these intergroup differences can be evaluated by any of a number of statistical tests appropriate for rates and proportions (e.g., fleiss, 1981; siegel and castellan, 1988). this winnowing process (1) removes those traits that will generate negatives values across all pairs of groups during calculation of the mmds, but (2) does not bias the mmds’ estimates. again, we contend that it is important to provide the full list of traits (and their trait frequencies) prior to the omission of noncontributory traits. as an optional third step, those mmds that are negative can be set to zero, both conceptually and practically, if subsequent use is to be made of them (such as input for cluster analysis or phenograms or other graphical representations). indeed, it is permissible to set all mmds that are less than twice their standard deviations to zero since, statistically, these estimates of the underlying population differences are nonsignificant. such values are simply within the range of random sampling fluctuations, so their expected values are zero. the error of “standardization” sofaer and colleagues (1986) introduced quite a different approach to calculating the mmd that they term “standardized mmd.” they developed their method to try and resolve a serious shortcoming of their data, namely: what if you want to develop a matrix of mmds for a set of samples, but you did not score the same suite of morphological traits for all of the groups? sofaer’s solution was creative, but wrong. in concept, one suite of traits ought to produce roughly the same phenetic relationships as another (e.g., sokal and sneath, 1963). if enough traits are used, and all of them possess the same inter-group relationships, and each trait produces the same magnitude of intergroup “distances,” then this would be approximately true. in actuality, of course, different sets of traits seldom produce comparable phenetic results. sofaer’s solution was to use mmds generated between pairs of groups—where different groups were represented by different traits and different numbers of traits. the authors then “standardized” the mmds by dividing each mmd by its standard deviation (using a formula similar to eq. 12). this was claimed to be analogous to the conventional z-score standardization, z= ( )x − µ σ [eq. 13] (e.g., sokal and rohlf, 1995:101-111) but the analogy quickly breaks down. recall that standardizing a normally distributed sample yields z-scores with a mean of zero and a stanmean measure of divergence 92 93 dard deviation of one (often termed “unit variance” since σ2 = 1 = σ). such a distribution occasionally is coded as n(0, 1). this standardization cannot be properly applied to a series of mmds—unless all of the mmds are zero (so µ = 0), in which case the operation is pointless. the whole purpose of calculating mmds among groups is that the groups differ according to some set of trait frequencies. more precisely, one supposes that the populations from which the samples are drawn possess meaningfully different trait frequencies; indeed, the degree of phenetic distance (mmd) is expected to differ among groups on a pair-by-pair basis—some groups being more similar and others more different than others for a given set of traits. for a given set of comparisons, some, most, or all of the mmds will be different from zero. regardless of particulars, the mmds will not be zero, nor will the mean of the mmds be zero. moreover, the standard deviation (eq. 12) is going to suffer from random variations in sample size from trait to trait. given that (1) most anthropological samples are modest in size, (2) they are samples of convenience (so sample size seldom can be controlled), (3) sample sizes differ among traits, sometimes dramatically, due to unscorable specimens, and (4) trait frequencies seldom vary much among groups, especially after sampling fluctuations are accounted for, “standardization” of mmds effectively is an exercise in introducing random errors of unknown magnitude that differ in unknown but differing ways from comparison to comparison depending on sample sizes and other random errors, also of unknown and differing magnitudes. there is, in fact, no analogy between the conventional z-score and sofaer ’s treatment of the mmds. with a set of mmds, the population mean is not zero, and there is a different standard deviation for every mmd (eq. 12). since these standard deviations are primarily tied to the sample sizes of the traits available in the study, “standardization” as described by sofaer et al. divides each mmd by a different and biologically meaningless value. we obviously see no merit—and several problems—with this attempt at “standardization.” problems with “standardization” seem obvious to us, but the method was applied uncritically by sutter and mertz (2004)—evidently with the passive assent of the reviewers as well. what strikes us as particularly unfortunate is that (1) the proper source of the “standardization” method (i.e., sofaer et al., 1986) does not even appear in the literature cited and (2) the method is wrongly-attributed (on their page 136) to sjøvold (1973), who decidedly did not mention or advocate any such approach. this error is yet another example of where hasty scholarship has created impediments to the correct calculation of mmds. summary the purpose of this note is to publicize the correct calculation of cedric a. b. smith’s mmd. this can be summarized in four steps: (1) eq. 6 is the correct formula for the mmd as devised by smith and modified by berry (1969); (2) smith’s arcsine transformation of trait frequencies should be replaced by anscombe’s transformation (eq. 3) and expressed in radians, not degrees; (3) the sampling correction in eq. 6 should be replaced by the more accurate term in eq. 7; and (4) the preliminary battery of traits should be tested univariately for among-group differences and those traits without statistically significant differences in frequencies across all samples should be omitted. additionally, bartlett’s adjustment should be applied when the sample trait frequency is fixed at 0 or 1. statistical significance between a pair of populations occurs when the mmd exceeds twice its standard deviation (eq. 12). the lack of statistical significance does not mean that the samples can be supposed to derive from the same population, but that it is not possible to distinguish the populations they come from by means of the data and/or the sample sizes available. literature cited anscombe fj. 1948. the transformation of poisson, binomial and negative-binomial data. biometrika 35:246-254. bartlett ms. 1936. the square root transformation in the analysis of variance. j roy stat soc suppl 3:68-78. berry ac. 1974. the use of non-metrical variations of the cranium in the study of scandinavian population movements. am j phys anthropol 40:345-358. berry ac. 1976. the anthropological value of minor variants of the dental crown. am j phys anthropol 45:257-268. berry ac, berry rj. 1967. epigenetic variation in the human cranium. j anat 101:361-379. berry rj. 1968. the biology of non-metrical variation in mice and men. in: brothwell dr, editor. the skeletal biology of earlier human populations. london: pergamon press, p 103-133. berry rj. 1969. history in the evolution of apodemus sylvaticus (mammalia) at one edge of its range. j zool london 159:311-328. cadien jd, harris ef, jones wp, mandarino lj. 1974. biological lineages, skeletal populations, and microevolution. yrbk phys anthropol 18:194-201. constandse-westermann ts. 1972. coefficients of biological distance. the netherlands: oosterhout n. b. corruccini rs. 1974. an examination of the meaning of cranial discrete traits for human skeletal biological studies. am j phys anthropol 40:425-445. e.f. harris and t. sjøvold 92 93 dahlberg aa. 1945. the paramolar tubercle (bolk). am j phys anthropol 3:97-103. deol ms. 1955. genetical studies on the skeleton of the mouse. xiv. minor variants of the skull. j genet 53: 498-514. fisher ld, van belle g. 1993. biostatistics: a methodology for the health sciences. new york: john wiley and sons, inc. fisher ra. 1958. statistical methods for research workers, 13th ed. london: oliver and boyd. fleiss jl. 1981. statistical methods for rates and proportions, 2nd ed. new york: john wiley & sons. freeman mf, tukey jw. 1950. transformations related to the angular and square root. ann math stat 21: 607-611. green rf, suchey jm. 1976. the use of inverse sine transformations in the analysis of non-metric cranial data. am j phys anthropol 45:61-68. green rf, suchey jm, gokhale dv. 1979. the statistical treatment of correlated bilateral traits in the analysis of cranial material. am j phys anthropol 50:629-634. grewal ms. 1962. the rate of genetic divergence in the c57bl strain of mice. genet res 3:226-237. grüneberg h. 1950. genetical studies on the skeleton of the mouse. i. minor variants of the vertebral column. j genet 50:112-141. hellman m. 1928. racial characters in human dentition. proc amer phil soc 67:157-174. hillson s. 1996. dental anthropology. cambridge: cambridge university press. hrdlička a. 1920. shovel-shaped teeth. am j phys anthropol 3:429-465. hrdlička a. 1922. further studies of tooth morphology. am j phys anthropol 4:141-176. lasker gw, lee mmc. 1957. racial traits in the human teeth. j forensic sci 2:401-419. mahalanobis pc. 1936. on the generalized distance in statistics. proc nat inst sci india 2:49-55. mayr e. 1963. animal species and evolution. cambridge: belknap press. morris dh, dahlberg aa, glasstone-hughes s. 1978. the uto-aztecan premolars—the anthropology of a dental trait. in: butler pm, joysey ka, editors. development, function, and evolution of the teeth. london: academic press, p 69-79. pearson k. 1926. on the coefficient of racial likeness. biometrika 18:105-117. penrose ls. 1953. distance, size and shape. ann eugenics 18:337-343. rao cr. 1952. advanced statistical methods in biometric research. new york: john wiley & sons. reyment ra. 1991. multidimensional palaeobiology. oxford: pergamon press. scott gr. 1977. lingual tubercles and the maxillary incisor-canine field. j dent res 56:1192. scott gr. 1978. the relationship between carabelli’s trait and the protostylid. j dent res 57:570. scott gr. 1979. association between the hypocone and carabelli’s trait of the maxillary molars. j dent res 58:1403. scott gr, turner cg ii. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. siegel s, castellan nj. 1988. nonparametric statistics for the behavioral sciences, 2nd ed. new york: mcgrawhill, inc. sjøvold t. 1973. the occurrence of minor non-metrical variants in the skeleton and their quantitative treatment for population comparisons. homo 24: 204-233. sjøvold t. 1977. non-metrical divergence between skeletal populations. ossa 4:suppl. 1. smith cab. 1972. coefficients of biological distance. ann hum genet 36:241-245. sofaer ja, smith p, kaye e. 1986. affinities between contemporary and skeletal jewish and non-jewish groups based on tooth morphology. am j phys anthropol 70:265-275. sokal rr, rohlf fj. 1995. biometry: the principles and practice of statistics in biological research, 3rd ed. san francisco: wh freeman and company. sokal rr, sneath pha. 1963. principles of numerical taxonomy. san francisco: wh freeman and company. sutter rc, mertz l. 2004. nonmetric cranial trait variation and prehistoric biocultural change in the azapa valley, chile. am j phys anthropol 123:130-145. tratman ek. 1938. three-rooted lower molars in man and their racial distribution. br dent j 64:264-274. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental morphology. new york: wiley-liss, p 13-32. editor’s note: copies of the publications by t. sjøvold (1973, 1977) are available by contacting the author: prof. torstein sjøvold osteology unit wallenberg laboratory stockholm university se-106 91 stockholm, sweden torstein.sjovold@ofl.su.se mean measure of divergence puech 1995.2 page 05.jpg page 06.jpg page 07.jpg da_07_02_puech 1992.1 pg3.jpg pg4.jpg khamis et al. 2006.3 49 in terms of historical migrations and interrelationships of people, malaysia has been compared to the united states of america (nagata, 1979) in being a home to many different people from different ethnic backgrounds. until now, descriptions of contemporary malaysian dental crown morphology have been lacking, with only two published reports available, as far as we aware. tratman (1950) described dental variations between mongoloids and indians from the malaysian peninsula and singapore. he combined malays and chinese into one regional group for his comparisons, while indians were categorized as representing indo-europeans; however, his report was limited to anatomical descriptions without statistical analyses (except for a few traits) due to loss of data during world war ii. another report on the dentition of malaysians by rusmah (1992) presented frequencies of occurrence for carabelli cusp, which was present in 52.2% of the sample. rusmah reported that no sexual dimorphism or bilateral asymmetry was evident for this trait. previous studies of dental affinities among asians have revealed that mongoloid people can be subdivided into sinodonts, represented by northern asians and native americans, and sundadonts comprising peoples of south-east asia (turner, 1987; 1990). from 28 traits used initially to separate east asians into northern and southern divisions, turner (1990) found eight traits that discriminated between sinodonts and sundadonts. all of these traits occurred more frequently in sinodonts, except for 4-cusped lower second molars. turner described sinodonts as having trait intensification, that is, higher frequencies of crown trait occurrence and addition (e.g., three rooted lower first molars), while sundadonts showed crown simplification or moderate frequencies of occurrence, and retention of old traits (e.g., two-rooted upper first premolars). traditionally, relationships among malaysian populations have been based only on historical perspectives. malays and orang asli are considered to be the natives of malaysia, while chinese and indians arrived for trade and economic opportunities mainly during the british colonization period in the early 19th century (nagata, 1979; pusat perkembangan kurikulum, 1998; zainuddin, 2003). many questions still remain about the origins of malaysians and their affinities from a biological point of view. it is important to describe the nature and extent of dental variation within populations before attempting to characterize variation between them. this includes variation in dental crown morphology in malaysian populations mohd fadhli khamis1*, jane a. taylor2, abdul rani samsudin1, and grant c. townsend3 1school of dental sciences, universiti sains malaysia, kota bharu, kelantan 16150 malaysia 2oral health, the university of newcastle, ourimbah, new south wales, australia 3school of dentistry, the university of adelaide, adelaide sa 5005, australia grant sponsorship: universiti sains malaysia short term grant 304/ppsg/6131274 and south australian police. *correspondence to: mohd fadhli khamis, school of dental sciences, health campus, universiti sains malaysia, kota bharu 16150 kelantan, malaysia. e-mail: fadhli@kb.usm.my abstract: dental crown variation was studied in the four main population groups living in malaysia using dental casts (upper and lower) obtained from 790 individuals. the aims of the study were to characterize variation in 13 dental crown traits, within groups as well as between groups, and to assess affinities between the groups based on frequencies of occurrence of dental features. using chi-square analysis and fisher’s exact test, the majority of dental traits were found to be bilaterally symmetrical and to demonstrate low sexual dimorphism. comparisons of trait frequencies between groups revealed similarities between malays, jahai (negritos) and chinese who conformed to mongoloid sinodont-sundadont dental patterns, whereas the indians conformed to an indo-european pattern. phenetic distance analysis, using the mean measure of divergence, showed that indians were markedly separated from the other three groups, while malays were closer to jahai than to chinese. these findings based on dental traits are consistent with historical explanations of affinities between modern malaysian populations. dental anthropology 2006;19(2):49-60. 50 consideration of the nature and extent of sexual dimorphism, bilateral asymmetry and inter-trait associations. scott and turner (1997) have concluded that dental morphological traits are suitable for population characterization due to their low sexual dimorphism and strong symmetry, and several researchers have found no evidence of significant sexual dimorphism for various dental traits (garn et al., 1966b; bang and hasund, 1971; bang and hasund, 1972; hanihara, 1977; turner and hanihara, 1977; turner and scott, 1977; hershey, 1979; scott, 1980; hassanali, 1982; mayhall et al., 1982; kieser, 1984; thomas et al., 1986; townsend et al., 1986; haeussler et al., 1989; townsend et al., 1990; manabe et al., 1992; rusmah, 1992; kannappan and swaminathan, 1998). other researchers, however, have noted higher frequencies for certain features in males (rothhammer et al., 1968; escobar et al., 1977; scott, 1977; townsend and brown, 1981; iwai-liao et al., 1996; hsu et al., 1997) and occasionally in females (harris and bailit, 1980). several studies have indicated that dental traits tend to be expressed symmetrically (baume and crawford, 1979; harris and bailit, 1980; noss et al., 1983b; townsend et al., 1990) while others have reported evidence of asymmetry (meredith and hixon, 1954; mayhall and saunders, 1986; moskona et al., 1996). given the limited information available about malaysian odontological variation, this study aimed to characterize variation of dental crown traits within four major malaysian ethnic groups prior to undertaking a study of the affinities between them. materials and methods a total of 790 sets of dental casts (maxillary and mandibular) were examined in this study. table 1 shows the sample distribution according to sex and age for each of the four ethnic groups. all groups comprised teenagers from the districts around kelantan and perak, except for the jahai (negritos) who were older. the jahai represent a sub-group of negritos who live mainly in the northern part of the malaysian peninsula. the negritos are one of three orang asli tribes who live only on the malaysian peninsula. power studies following the methods of dupont and plummer (1997) indicated that sample sizes of 72 for each group would be sufficient to provide 80% power for our study. logistic, financial and time constraints restricted the number of jahai who could be recruited into the study and, consequently, results for this group should be interpreted with caution. the classification of dental crown traits, except those for the entoconulid, carabelli trait and groove pattern, was simplified from the arizona state university (asu) classification system (turner et al., 1991). teeth were not scored if wear obscured the trait under investigation. the asu reference plaques were used when scoring all traits to provide additional guidance. the definition of townsend et al. (1990) was used for entoconulid classification as it includes observation of the entoconulid on four-cusped molars, whereas the asu system only scores entoconulids on five-cusped molars. carabelli trait was scored according to dahlberg’s plaque p12a, and molar groove pattern was assessed using plaque p10 (dahlberg, 1956). for the other traits, the original asu gradings were simplified into two or three grades of expression only (table 2). table 2 also provides the breakpoints chosen for the dichotomous data. dental casts for 167 individuals were scored twice and intra-observer errors for graded scales and presence/ absence for all traits were calculated as percentages of discordance following nichol and turner (1986). these authors set 10% discordance as a benchmark for 2-grade discrepancies and presence-absence data. the extent of asymmetrical expression of the dental traits in males was compared initially with that in females using chi-square analysis or fisher’s exact test when expected cell frequencies were less than five (howitt and cramer, 2003). absent-absent pairs were excluded from the analysis. these preliminary tests were used to determine whether it would be appropriate to pool data for subsequent analyses of symmetry/asymmetry. an adjusted alpha level was set at 0.05/12 = 0.004 (bonferroni’s adjustment). comparisons of the frequencies of occurrence of dental traits on corresponding right and left teeth were tested using non-parametric analyses, either fisher’s exact test, or monte carlo estimates (spss inc., 19892001, version 11.0.1). frequencies of occurrence and degrees of expression were calculated for all traits. sexual dimorphism was ethnic mean group sex n (years) sd malays female 167 15.6 1.2 male 126 15.1 1.3 total 293 15.4 1.3 chinese female 88 14.5 1.3 male 90 14.7 1.5 total 178 14.6 1.4 indians female 131 15.8 1.4 male 121 15.6 1.3 total 252 15.7 1.3 negritos female 33 28.3 8.2 (jahai) male 34 30.5 13.1 total 67 29.4 10.9 total female 419 16.4 4.4 male 371 16.6 6.1 total 790 16.5 5.2 1n is sample size; sd is standard deviation table 1. distribution of participants according to sex and age within four ethnic groups1 m.f. khamis et al. 51dental variation in malaysian populations asu breakpoint for trait tooth classification grade score1 dichotomous data2 winging 11,21 bilateral winging 1 1 1-present unilateral winging 2 2 2,3-absent counter wing and straight 3,4 3 shovel 11,21 absent 0 0 0,1-absent trace 1,2 1 2,3-present semi 3,4 2 shovel 5,6 3 metaconule 16,26 absent 0 0 0-absent weak cuspule 1,2 1 1,2,3-present small cuspule 3 2 small to moderate cusp 4,5 3 carabelli trait3 16,26 absent a 0 0-absent pit & furrow b,c 1 123-present tubercle d,e,f,g 2 cusp h 3 hypocone 17,27 absent or ridge 0,1 0 0,1-absent cuspule 2 1 2,3-present reduced cusp 3,4 2 large 5,6 3 distal accessory ridge 33,43 absent 0 0 0-absent weak 1,2 1 1,2-present strong 3,4,5 2 lingual cusp number 35,45 one 1 1-one cusp two 2 three 3 2,3,4-not one cusp four 4 protostylid 36,46 absent 0 0 0-absent weak 1,2,3 1 1,2-present strong 4,5,6,7 2 metaconulid 36,46 absent 0,1,5 0 0-absent small 1,2,3 1 1,2-present large 4 2 entoconulid 36,46 absent 0 0 0-absent weak 1,2 1 1,2-present strong 3,4 2 deflecting wrinkle 36,46 absent 0,1 0 0,1-absent weak 2 1 2-present strong 3 2 cusp number 37,47 four 4 4-four cusp five 5 5,6-not four cusp six 6 groove pattern4 37,47 y y 1 1-y pattern + + 2 2,3-+,x pattern x x 3 1score used in this study 2breakpoint based on1 3observation using dahlberg plaque p12a 4observation using dahlberg plaque p10. table 2. dental crown trait classification used in this study 52 negritos traits and teeth malays chinese indians (jahai) shovel 11,21 n 266 170 218 46 % symmetry 95.1a 90.6a 96.8a 100.0a % symmetry (absent-absent exc.) 95.0 90.6 96.7 100.0 rho 0.91b 0.80b 0.93b 1.00b carabelli trait 16,26 n 275 170 238 46 % symmetry 83.6a 88.8a 81.1a 78.3a % symmetry (absent-absent exc.) 80.7 84.8 78.3 76.7 rho 0.81b 0.91b 0.73b 0.81b metaconule 16,26 n 223 165 204 36 % symmetry 82.1a 79.4a 81.4a 69.4a % symmetry (absent-absent exc.) 71.2 63.4 73.8 57.7 rho 0.82b 0.73b 0.83b 0.62b hypocone reduction 17,27 n 231 127 192 54 % symmetry 86.6a 84.3a 84.9a 92.6a % symmetry (absent-absent exc.) rho 0.88b 0.82b 0.83b 0.80b distal accessory ridge 33,43 n 278 165 230 53 % symmetry 85.3a 81.8a 90.4a 90.6a % symmetry (absent-absent exc.) 59.0 48.3 60.7 68.8 rho 0.68b 0.56b 0.71b 0.75b lingual cusp number 35,45 n 263 155 235 59 % symmetry 84.0a 85.8a 84.3a 86.4 % symmetry (absent-absent exc.) rho 0.63b 0.74b 0.74b 0.43b protostylid 36,46 n 248 146 227 37 % symmetry 87.5a 96.6a 93.0a 91.9a % symmetry (absent-absent exc.) 76.5 94.5 77.8 66.7 rho 0.80b 0.95b 0.88b 0.73b deflecting wrinkle 36,46 n 159 105 196 19 % symmetry 76.7a 79.0a 87.2a 100.0a % symmetry (absent-absent exc.) 51.9 52.2 69.9 100.0 rho 0.61b 0.63b 0.78b 1.00b metaconulid 36,46 n 258 167 235 43 % symmetry 95.7a 96.4a 94.0a 95.3a % symmetry (absent-absent exc.) 35.3 53.8 41.7 60.0 rho 0.50b 0.76b 0.76b 0.75b entoconulid 36.46 n 244 161 218 31 % symmetry 94.3a 91.3a 95.0a 80.6a % symmetry (absent-absent exc.) 77.0 67.4 79.2 40.0 rho 0.85b 0.77b 0.87b 0.53b continued table 3. tests of bilateral symmetry for 12 dental crown traits using graded-scale data (pooled-sex data)1 m.f. khamis et al. 53dental variation in malaysian populations assessed using univariate non-parametric analyses. bonferroni’s adjustment was adopted for multiple univariate testing (13 independent variables) to control type 1 error. the alpha level of 0.05 was divided by 13, yielding an adjusted alpha value of 0.0037. calculation of the mean measure of divergence (mmd) between groups took account of the issues raised by harris and sjøvold (2004) and (irish, 2006). differences in the frequencies of occurrence of each of the 13 dental traits between the four groups were analyzed using chi-square analysis at an alpha level of 0.05 to identify influential traits. according to harris and sjøvold (2004), these tests are important for selection of traits, as only those associated with significant outcomes should be used as input into the mean measure of divergence (mmd) computations to avoid negative values. these researchers also recommended that negative mmd coefficients be replaced with zero only when the coefficients are used for subsequent graphical representation. the mmd analysis utilized dichotomous data. the frequencies of occurrence were transformed using anscombe computations (equation 2) to stabilize sampling variance. harris and sjøvold (2004) defined the computation of the mmd as follows: “the difference between samples i and j for the frequencies of trait k is calculated and then this difference is squared and the correction term is subtracted. the sum of corrected squared differences was averaged according to the number of traits.” mean measure of divergence (mmd) is mmd = 1 r θ ik -θ jk( ) 2 1 n ik +0.5 + 1 n jk +0.5       k = 1 r ∑ r, number of traits k, dental trait i, j, samples from group i ,j n ik , scorable samples in i group for trait k n jk , scorable samples in j group for trait k anscombe’s transformation, θ = sin 1-2 m+ 3 8 n+ 3 4 -1                     m, frequency of trait presence n, scorable specimens the standard deviation of mmd is sd = 2 r 1 n + 1 n2 ik jk 2 k=1 r      ∑ the mmd coefficients are considered to be significant at an alpha level of 5% when they are twice the corresponding standard deviations. for ease of interpretation, mmd coefficients were used as input into a hierarchical cluster analysis to generate a classification tree dendrogram. clustering methods used ward’s linkage and measurement between pairs of groups was based on squared euclidean distance. the output was rescaled to numbers between 0 and 25. negritos traits and teeth malays chinese indians (jahai) cusp number 37,47 n 232 132 188 41 % symmetry 85.8a 83.3a 92.6a 87.8a % symmetry (absent-absent exc.) rho 0.82b 0.78b 0.84b 0.77b groove pattern 37,47 n 223 132 206 35 % symmetry 77.1a 78.8a 76.7a 68.6 % symmetry (absent-absent exc.) rho 0.63b 0.63b 0.68b 0.36 1exc, excluded; the dashes (-) indicate that no analysis was performed because definition of “absent” is equivocal. ap = 0.0037 bp < 0.05 table 3. continued 54 dental variation in malaysian populations m al ay s c h in es e in d ia n s n eg ri to s tr ai ts sc or e m f t m f t m f t m f t n 12 5 16 4 28 9 89 87 17 6 12 8 11 6 24 4 32 27 59 w in gi n g 1 11 .2 (1 4) 7. 9( 13 ) 9. 3( 27 ) 13 .5 (1 2) 17 .2 (1 5) 15 .3 (2 7) 2. 6( 3) 4. 7( 6) 3. 7( 9) 28 .1 (9 ) 14 .8 (4 ) 22 .0 (1 3) 2 6. 4( 8) 4. 3( 7) 5. 2( 15 ) 7. 9( 7) 11 .5 (1 0) 9. 7( 17 ) 9. 5( 11 ) 4. 7( 6) 7. 0( 17 ) 15 .6 (5 ) 3. 7( 1) 10 .2 (6 ) 3 82 .4 (1 03 ) 87 .8 (1 44 ) 85 .5 (2 47 ) 78 .7 (7 0) 71 .3 (6 2) 75 .0 (1 32 ) 87 .9 (1 02 ) 90 .6 (1 16 ) 89 .3 (2 18 ) 56 .3 (1 8) 81 .5 (2 2) 67 .8 (4 0) n 11 8 15 9 27 7 88 84 17 2 11 5 12 6 24 1 25 26 51 sh ov el 0 2. 5( 3) 1. 3( 2) 1. 8( 5) 0. 0( 0) 0. 0( 0) 0. 0( 0) 3. 5( 4) 4. 0( 5) 3. 7( 9) 12 .0 (3 ) 3. 8( 1) 7. 8( 4) 1 57 .6 (6 8) 54 .7 (8 7) 56 .0 (1 55 ) 21 .6 (1 9) 27 .4 (2 3) 24 .4 (4 2) 73 .9 (8 5) 69 .0 (8 7) 71 .4 (1 72 ) 64 .0 (1 6) 76 .9 (2 0) 70 .6 (3 6) 2 39 .0 (4 6) 43 .4 (6 9) 41 .5 (1 15 ) 75 .0 (6 6) 72 .6 (6 1) 73 .8 (1 27 ) 21 .7 (2 5) 27 .0 (3 4) 24 .5 (5 9) 24 .0 (6 ) 19 .2 (5 ) 21 .6 (1 1) 3 0. 8( 1) 0. 6( 1) 0. 7( 2) 3. 4( 3) 0. 0( 0) 1. 7( 3) 0. 0( 0) 0. 9( 1) 0. 4( 1) 0. 0( 0) 0. 0( 0) 0. 0( 0) n 11 9 15 7 27 6 89 88 17 7 12 6 11 1 23 7 28 26 54 m et ac on u le 0 37 .0 (4 4) 42 .7 (6 7) 40 .2 (1 11 ) 40 .4 (3 6) 45 .5 (4 0) 42 .9 (7 6) 22 .5 (2 5) 29 .4 (3 7) 26 .2 (6 2) 39 .3 (1 1) 19 .2 (5 ) 29 .6 (1 6) 1 33 .6 (4 0) 28 .7 (4 5) 30 .8 (8 5) 27 .0 (2 4) 25 .0 (2 2) 26 .0 (4 6) 48 .6 (5 4) 38 .1 (4 8) 43 .0 (1 02 ) 35 .7 (1 0) 61 .5 (1 6) 48 .1 (2 6) 2 26 .1 (3 1) 23 .6 (3 7) 24 .6 (6 8) 27 .0 (2 4) 28 .4 (2 5) 27 .7 (4 9) 22 .5 (2 5) 30 .2 (3 8) 26 .6 (6 3) 21 .4 (6 ) 19 .2 (5 ) 20 .4 (1 1) 3 3. 4( 4) 5. 1( 8) 4. 3( 12 ) 5. 6( 5) 1. 1( 1) 3. 4( 6) 6. 3( 7) 2. 4( 3) 4. 2( 10 ) 3. 6( 1) 0. 0( 0) 1. 9( 1) n 12 6 16 4 29 0 88 88 17 6a 11 8 13 1 24 9 30 33 63 c ar ab el li t ra it 0 15 .1 (1 9) 15 .9 (2 6) 15 .5 (4 5) 14 .8 (1 3) 38 .6 (3 4) 26 .7 (4 7) 11 .0 (1 3) 16 .8 (2 2) 14 .1 (3 5) 6. 7( 2) 21 .2 (7 ) 14 .3 (9 ) 1 7. 9( 10 ) 14 .6 (2 4) 11 .7 (3 4) 12 .5 (1 1) 8. 0( 7) 10 .2 (1 8) 25 .4 (3 0) 14 .5 (1 9) 19 .7 (4 9) 10 .0 (3 ) 18 .2 (6 ) 14 .3 (9 ) 2 65 .1 (8 2) 63 .4 (1 04 ) 64 .1 (1 86 ) 63 .6 (5 6) 50 .0 (4 4) 56 .8 (1 00 ) 56 .8 (6 7) 66 .4 (8 7) 61 .8 (1 54 ) 56 .7 (1 7) 57 .6 (1 9) 57 .1 (3 6) 3 11 .9 (1 5) 6. 1( 10 ) 8. 6( 25 ) 9. 1( 8) 3. 4( 3) 6. 3( 11 ) 6. 8( 8) 2. 3( 3) 4. 4( 11 ) 26 .7 (8 ) 3. 0( 1) 14 .3 (9 ) n 11 4 14 8 26 2 76 70 14 6 10 6 11 7 22 3 33 29 62 h yp oc on e 0 17 .5 (2 0) 20 .3 (3 0) 19 .1 (5 0) 13 .2 (1 0) 27 .1 (1 9) 19 .9 (2 9) 30 .2 (3 2) 39 .3 (4 6) 35 .0 (7 8) 0. 0( 0) 13 .8 (4 ) 6. 5( 4) 1 2. 6( 3) 5. 4( 8) 4. 2( 11 ) 1. 3( 1) 8. 6( 6) 4. 8( 7) 4. 7( 5) 6. 0( 7) 5. 4( 12 ) 0. 0( 0) 0. 0( 0) 0. 0( 0) 2 60 .5 (6 9) 58 .1 (8 6) 59 .2 (1 55 ) 76 .3 (5 8) 54 .3 (3 8) 65 .8 (9 6) 45 .3 (4 8) 44 .4 (5 2) 44 .8 (1 00 ) 54 .5 (1 8) 51 .7 (1 5) 53 .2 (3 3) 3 19 .3 (2 2) 16 .2 (2 4) 17 .6 (4 6) 9. 2( 7) 10 .0 (7 ) 9. 6( 14 ) 19 .8 (2 1) 10 .3 (1 2) 14 .8 (3 3) 45 .5 (1 5) 34 .5 (1 0) 40 .3 (2 5) n 12 6 16 4 29 0 90 86 17 6 11 6 12 9 24 5 29 31 60 a d is ta l a cc es s. r id ge 0 61 .9 (7 8) 67 .1 (1 10 ) 64 .8 (1 88 ) 54 .4 (4 9) 74 .4 (6 4) 3. 3( 3) 74 .1 (8 6) 76 .7 (9 9) 75 .5 (1 85 ) 44 .8 (1 3) 87 .1 (2 7) 66 .7 (4 0) 1 34 .1 (4 3) 31 .1 (5 1) 32 .4 (9 4) 42 .2 (3 8) 25 .6 (2 2) 0. 0( 0) 24 .1 (2 8) 22 .5 (2 9) 23 .3 (5 7) 55 .2 (1 6) 12 .9 (4 ) 33 .3 (2 0) 2 4. 0( 5) 1. 8( 3) 2. 8( 8) 3. 3( 3) 0. 0( 0) 1. 7( 3) 1. 7( 2) 0. 8( 1) 1. 2( 3) 0. 0( 0) 0. 0( 0) 0. 0( 0) c on ti n u ed t a b l e 4 . p er ce n ta ge s of o cc u rr en ce a n d se xu al d im or ph is m fo r 13 d en ta l t ra it s u si n g th e in di vi du al c ou n t m et ho d an d gr ad ed -s ca le d at a in fo u r et hn ic g ro u ps 1 55m.f. khamis et al. m al ay s c h in es e in d ia n s n eg ri to s tr ai ts sc or e m f t m f t m f t m f t n 12 1 16 3 28 4 89 83 17 2 11 9 12 9 24 8 33 33 66 l in g. c u sp n o. l p 2 1 27 .3 (3 3) 16 .6 (2 7) 21 .1 (6 0) 29 .2 (2 6) 24 .1 (2 0) 26 .7 (4 6) 34 .5 (4 1) 21 .7 (2 8) 27 .8 (6 9) 15 .2 (5 ) 6. 1( 2) 10 .6 (7 ) 2 67 .8 (8 2) 79 .8 (1 30 ) 74 .6 (2 12 ) 65 .2 (5 8) 69 .9 (5 8) 67 .4 (1 16 ) 55 .5 (6 6) 72 .1 (9 3) 64 .1 (1 59 ) 78 .8 (2 6) 93 .9 (3 1) 86 .4 (5 7) 3 5. 0( 6) 3. 1( 5) 3. 9( 11 ) 5. 6( 5) 6. 0( 5) 5. 8( 10 ) 10 .1 (1 2) 6. 2( 8) 8. 1( 20 ) 6. 1( 2) 0. 0( 0) 3. 0( 2) 4 0. 0( 0) 0. 6( 1) 0. 4( 1) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) 0. 0( 0) n 12 4 15 8 28 2 82 82 16 4 11 8 12 9 24 7 28 23 51 p ro to st yl id 0 43 .5 (5 4) 48 .1 (7 6) 46 .1 (1 30 ) 28 .0 (2 3) 41 .5 (3 4) 34 .8 (5 7) 72 .0 (8 5) 64 .3 (8 3) 68 .0 (1 68 ) 67 .9 (1 9) 69 .6 (1 6) 68 .6 (3 5) 1 4. 8( 6) 3. 2( 5) 3. 9( 11 ) 12 .2 (1 0) 8. 5( 7) 10 .4 (1 7) 1. 7( 2) 4. 7( 6) 3. 2( 8) 0. 0( 0) 8. 7( 2) 3. 9( 2) 2 51 .6 (6 4) 48 .7 (7 7) 50 .0 (1 41 ) 59 .8 (4 9) 50 .0 (4 1) 54 .9 (9 0) 26 .3 (3 1) 31 .0 (4 0) 28 .7 (7 1) 32 .1 (9 ) 21 .7 (5 ) 27 .5 (1 4) n 12 4 16 3 28 7 89 88 17 7 12 0 12 7 24 7 30 25 55 m et ac on u li d 0 90 .3 (1 12 ) 95 .7 (1 56 ) 93 .4 (2 68 ) 89 .9 (8 0) 95 .5 (8 4) 92 .7 (1 64 ) 87 .5 (1 05 ) 91 .3 (1 16 ) 89 .5 (2 21 ) 83 .3 (2 5) 96 .0 (2 4) 89 .1 (4 9) 1 8. 9( 11 ) 4. 3( 7) 6. 3( 18 ) 5. 6( 5) 2. 3( 2) 4. 0( 7) 6. 7( 8) 6. 3( 8) 6. 5( 16 ) 10 .0 (3 ) 4. 0( 1) 7. 3( 4) 2 0. 8( 1) 0. 0( 0) 0. 3( 1) 4. 5( 4) 2. 3( 2) 3. 4( 6) 5. 8( 7) 2. 4( 3) 4. 0( 10 ) 6. 7( 2) 0. 0( 0) 3. 6( 2) n 12 4 15 7 28 1 89 88 17 7 11 5 12 4 23 9 21 22 43 e n to co n u li d 0 77 .4 (9 6) 72 .0 (1 13 ) 74 .4 (2 09 ) 64 .0 (5 7) 79 .5 (7 0) 71 .8 (1 27 ) 81 .7 (9 4) 70 .2 (8 7) 75 .7 (1 81 ) 57 .1 (1 2) 77 .3 (1 7) 67 .4 (2 9) 1 21 .0 (2 6) 26 .8 (4 2) 24 .2 (6 8) 31 .5 (2 8) 19 .3 (1 7) 25 .4 (4 5) 16 .5 (1 9) 29 .0 (3 6) 23 .0 (5 5) 38 .1 (8 ) 18 .2 (4 ) 27 .9 (1 2) 2 1. 6( 2) 1. 3( 2) 1. 4( 4) 4. 5( 4) 1. 1( 1) 2. 8( 5) 1. 7( 2) 0. 8( 1) 1. 3( 3) 4. 8( 1) 4. 5( 1) 4. 7( 2) n 10 5 13 1 23 6 71 78 14 9 11 4 11 8 23 2 9 17 26 d efl ec ti n g w ri n kl e 0 49 .5 (5 2) 54 .2 (7 1) 52 .1 (1 23 ) 52 .1 (3 7) 62 .8 (4 9) 57 .7 (8 6) 57 .0 (6 5) 56 .8 (6 7) 56 .9 (1 32 ) 88 .9 (8 ) 88 .2 (1 5) 88 .5 (2 3) 1 37 .1 (3 9) 31 .3 (4 1) 33 .9 (8 0) 28 .2 (2 0) 19 .2 (1 5) 23 .5 (3 5) 36 .0 (4 1) 30 .5 (3 6) 33 .2 (7 7) 11 .1 (1 ) 5. 9( 1) 7. 7( 2) 2 13 .3 (1 4) 14 .5 (1 9) 14 .0 (3 3) 19 .7 (1 4) 17 .9 (1 4) 18 .8 (2 8) 7. 0( 8) 12 .7 (1 5) 9. 9( 23 ) 0. 0( 0) 5. 9( 1) 3. 8( 1) n 11 6 15 0 26 6 80 75 15 5 10 5 11 2 21 7 24 24 48 c u sp n o. l m 2 4 45 .7 (5 3) 49 .3 (7 4) 47 .7 (1 27 ) 26 .3 (2 1) 50 .7 (3 8) 38 .1 (5 9) 72 .4 (7 6) 80 .4 (9 0) 76 .5 (1 66 ) 58 .3 (1 4) 62 .5 (1 5) 60 .4 (2 9) 5 47 .4 (5 5) 41 .3 (6 2) 44 .0 (1 17 ) 56 .3 (4 5) 37 .3 (2 8) 47 .1 (7 3) 26 .7 (2 8) 17 .9 (2 0) 22 .1 (4 8) 37 .5 (9 ) 33 .3 (8 ) 35 .4 (1 7) 6 6. 9( 8) 9. 3( 14 ) 8. 3( 22 ) 17 .5 (1 4) 12 .0 (9 ) 14 .8 (2 3) 1. 0( 1) 1. 8( 2) 1. 4( 3) 4. 2( 1) 4. 2( 1) 4. 2( 2) n 11 6 15 0 26 6 79 77 15 6 11 4 12 4 23 8 25 25 50 g ro ov e p at te rn 1 6. 9( 8) 10 .0 (1 5) 8. 6( 23 ) 6. 3( 5) 5. 2( 4) 5. 8( 9) 36 .8 (4 2) 41 .9 (5 2) 39 .5 (9 4) 4. 0( 1) 4. 0( 1) 4. 0( 2) 2 59 .5 (6 9) 60 .7 (9 1) 60 .2 (1 60 ) 57 .0 (4 5) 61 .0 (4 7) 59 .0 (9 2) 51 .8 (5 9) 46 .8 (5 8) 49 .2 (1 17 ) 68 .0 (1 7) 80 .0 (2 0) 74 .0 (3 7) 3 33 .6 (3 9) 29 .3 (4 4) 31 .2 (8 3) 36 .7 (2 9) 33 .8 (2 6) 35 .3 (5 5) 11 .4 (1 3) 11 .3 (1 4) 11 .3 (2 7) 28 .0 (7 ) 16 .0 (4 ) 22 .0 (1 1) 1 n is s am p le s iz e; g ro u p c od es a re : m al es ( m ), f em al es ( f) , a n d t ot al o f m al es a n d f em al es ( t ); f re q u en ci es o f oc cu rr en ce a re s h ow n in p ar en th es es . a p = 0 .0 03 7. t a b l e 4 . c on ti n u ed 56 results most of the intra-observer errors using absencepresence data were less than 10% and only 15 of 100 intra-observer error observations were in the range of 11% to 18%. the percentages of error recorded for fullgrade scoring were higher than for absence-presence data and the differences were only one grade apart. the patterns of symmetry-asymmetry were similar in both sexes, except for hypocone reduction in chinese and jahai, and the metaconulid in indians. after combining the data for both sexes, most traits were expressed symmetrically based on high to moderate values of correlation coefficients and concordance analyses (table 3). table 4 shows frequencies of occurrence of dental traits in males and females for each of the four ethnic groups. winging of upper central incisors, shoveling, metaconule, deflecting wrinkle, groove pattern, metaconulid, protostylid, hypocone, lingual cusp number of premolar, four-cusped lower second molar, and entoconulid showed no evidence of significant sexual dimorphism in any of the four ethnic groups. sexual dimorphism was found to be significant at an alpha level of 5% (bonferroni’s adjustment) for a couple of traits. carabelli cusp (maximum expression of carabelli trait) occurred more frequently in males than females in the chinese sample, while pit and furrow forms were more frequent in female chinese. the distal accessory ridge was significantly more frequent in jahai males than females. figure 1 shows significant differences at the 5% significance level in the frequencies of occurrence of 11 dental traits (sexes combined) between the four ethnic groups and compares the overall profiles of frequencies between the four ethnic groups. ethnic group differences were not significant for two dental traits; entoconulid and metaconulid. malays showed intermediate frequencies of occurrences for all dental traits while chinese tended to show high frequencies for some traits and low frequencies for others. shoveling, winging, protostylid, deflecting wrinkle, distal accessory ridge, dental variation in malaysian populations and one-lingual cusped premolar frequencies were high in chinese, whereas carabelli trait, metaconule and fourcusped molars were the least frequently observed traits. the indian group was characterized by a high frequency of carabelli trait, metaconule, reduced hypocone, fourcusped lower second molars and y-groove patterns, and a low frequency of winging, shoveling, distal accessory ridge, protostylid and entoconulid. the jahai exhibited low frequencies of occurrences of shoveling, hypocone reduction, one-cusped premolars, deflecting wrinkle, and y-groove patterns. only winging frequency was found to be high in the jahai cohort. differences of 10% or less in frequencies of occurrence were not associated with statistical significance, as shown by the entoconulid and metaconulid. nine dental traits discriminated indians from malays and chinese. five showed high frequencies in malays and chinese; namely, winging, shoveling, distal accessory ridge, protostylid, deflecting wrinkle, whereas four were associated with high frequencies in indians: metaconule, hypocone reduction, four-cusped lower second molars, and y-groove pattern. four other dental traits were not discriminative; carabelli trait, one-cusped premolars, entoconulid and metaconulid. when comparing malays and chinese, winging, shoveling, one-cusped premolars, protostylid and deflecting wrinkle were present more frequently in chinese, while carabelli trait and four-cusped molars were more frequent in malays. all other dental traits examined did not discriminate between malays and chinese. table 5 shows the mmd coefficients matrix including tests of significance. all mmd coefficients were statistically significant at p < 0.05. mmd coefficients derived from an average of 11 dental traits (the frequencies of entoconulid and metaconulid were not statistically significant in all four ethnic groups and were, therefore, excluded from the mmd analysis) were further subjected to hierarchical cluster analysis to produce a dendrogram. figure 2 shows the affinities between the four ethnic groups. indians were separated at a rescaled number of 25 from the other three groups; malays, jahai and chinese. at a rescaled number of approximately 14, chinese were separated from malays and jahai. discussion despite considerable time spent on training, the intra-observer error rates for some traits in this study were larger than those reported in other studies (turner and scott, 1977; turner, 1987; turner, 1990). this reflects the subjectivity involved in scoring methods for dental morphology. the categorical nature of the available scoring systems does not allow grading of the quasicontinuous spectra of tooth morphologies that may fall between categories. nichol and turner (1986) indicated that if a discordance of more than two-grades occurred, fig. 1. frequencies of occurrence of dental crown traits in four ethnic groups using dichotomous data. 57 and the presence-absence discordance was more than 10%, then problems exist in the scoring method. comparing intra-observer error for full-graded scoring and presence-absence scoring between this study and that of nichol and turner (1986) revealed similar results for entoconulid, groove pattern, cusp number of lower second molar and hypocone reduction. the results in the present study indicated better reliability for scoring several traits including shoveling, carabelli trait, distal accessory ridge, deflecting wrinkle, protostylid and lingual cusp number of lower second premolar, whereas results for the metaconule and winging were slightly better in the study by nichol and turner (1986). difficult traits to score consistently in the three major ethnic groups were the metaconule and distal accessory ridge using dichotomous categories. this study confirmed, as one would expect, that dichotomous data display better reliability, as quantified by concordance rates, than full-graded scoring methods. consistent with those results, palomino et al. (1977) indicated their preference for using dichotomous data rather than fullgraded scoring methods that increase the likelihood of misclassification. bilateralism was expressed similarly in males and females for all four ethnic groups. this result justified combining males and females for subsequent asymmetrysymmetry analysis. the frequencies of occurrence and degrees of expression of most traits showed significant symmetry, reflecting common developmental control for both sides of the dentition (potter et al., 1976). exceptions were lingual cusp number and groove pattern in jahai, suggesting caution is needed in using dental traits observed on the distal tooth of a series because these teeth showed evidence of higher asymmetry (garn et al., 1966a). however, these traits are useful to comparing trait simplification between groups. several of our findings were similar to those of previous studies in other populations. percentages of symmetrical expression were generally higher than 75% for the majority of traits, similar to findings of harris and bailit (1980) and noss et al. (1983b). when absence-absence pairs were excluded from the analysis, symmetry percentages were reduced (mayhall and saunders, 1986) especially for traits displaying low frequencies of occurrence (townsend et al., 1990). two traits in jahai, lingual cusp number of lower second premolars and molar groove pattern, did not exhibit significant symmetry and were associated with moderate to low correlations in contrast to the results of baume and crawford (1979) who reported strong correlations but non-significant symmetry in mexican and belizean populations. several traits showed high symmetry but the values of correlation coefficients were not consistently high. percentages of concordance between sides, when absent-absent pairs were excluded, paralleled the values of correlation coefficients. excluding absent-absent pairs is thought to reduce bias in the analysis of asymmetry (townsend et al., 1990). assessment of asymmetry for each grade revealed large discordance for several traits, ranging from absence on one side to maximum expression on the antimeric tooth. this occurred infrequently and to varying degrees among the four ethnic groups. two traits consistently showed large discordances in the four ethnic groups; deflecting wrinkle and protostylid. there were three traits, shoveling, carabelli trait and distal accessory ridge, which were consistently free from large discordances in all four ethnic groups. in conclusion, the present findings support the premise of common genetic control on both sides of the dentition with environmental influences causing minor deviation from perfect symmetry. this suggests that replacement of missing values with antimeric values is biologically and statistically acceptable. significant sexual dimorphism (after bonferroni’s adjustment) was found only in chinese and jahai; carabelli trait in chinese and distal accessory ridge on the canine in the jahai. the distal accessory ridge was found more often in jahai males, which is consistent with scott (1977) who studied the frequencies and degrees of expression of the distal accessory ridge in seven ethnic groups in the united states of america. carabelli trait in malaysian chinese was more common in males, a similar result to that reported in japanese and chinese samples (iwai-liao et al., 1996), southern chinese (hsu et al., 1999), australian aborigines (townsend and brown, 1981) and indian jats (kaul and prakash, 1981). in contrast, hanihara (1977), turner and hanihara (1977), scott (1980), manabe et al. (1992) and rusmah (1992) did not find any sexual dimorphism in the occurrence of this trait. in essence, the amount of sexual dimorphism for dental trait expression seems to vary between different malays chinese indians jahai malays ---0.068 0.144 0.075 chinese 0.000 ---0.320 0.227 indians 0.000 0.000 ---0.186 jahai 0.000 0.000 0.000 ---1tests of significance in cells below diagonal; mmd coefficients in cells above diagonal. table 5. mean measure of divergence coefficients matrix1 fig. 2. dendrogram of four ethnic groups with sexes pooled. 58 populations. based on our preliminary analyses of within-group variations, the 13 dental traits scored in this study were considered to be suitable for population variation studies (turner et al., 1991). this suitability was based on several criteria, such as an apparently strong genetic influence on the ontogeny of the traits (tocheri, 2000), low sexual dimorphism and strong symmetry. inter-sample comparisons have been used in the past to define so-called “racial dental complexes” for mongoloid, caucasoid and australoid groups. hanihara’s (1968) mongoloid dental complex identifies four traits, ui1 and ui2 shoveling, deflecting wrinkle, protostylid and metaconule. in our samples the observed dental traits generally conformed to accepted models, except for the metaconule, for which the indian sample displayed the highest frequency compared with malays, chinese and jahai. according to turner’s mongoloid dichotomy (turner, 1990), four crown traits distinguish sinodonts from sundadonts. shoveling, double shoveling and deflecting wrinkle are common in sinodonts, whereas 4cusped lower second molar are common in sundadonts. in our results jahai and malays fitted the sundadont description, while chinese showed the sinodont crown trait pattern. tratman (1950) described indians as indo-europeans who frequently exhibit carabelli trait, and the malays and chinese as mongoloids who show high frequencies of shoveling, double shoveling, entoconulid and more complex occlusal surfaces. in our study, findings for malays, chinese and jahai were consistent with some of tratman’s comments but those for carabelli trait, entoconulid and double shoveling were not. double shoveling was not scored in our study. the entoconulid did not provide statistically significant discrimination in the present study, although indians exhibited the lowest relative frequency. the frequencies of carabelli trait found in this study were generally high when compared with other published material for mongoloid populations (rusmah, 1992; iwai-liao et al., 1996; hsu et al., 1999). only one article about wainwright eskimos by hershey (1979) provides figures that approximate those obtained for carabelli trait in this study. hershey found a 92% frequency of occurrence for carabelli trait while in this mongoloid sample the frequency was around 75%85%. an unexpected trend was found in the cuspal category (maximum expression for carabelli trait). according to tratman (1950), indians should have a high frequency of carabelli cusp but in this study they actually recorded the lowest frequency of 4.4% only. several other researchers including kraus (1959), hershey (1979), mayhall et al. (1982), and mayhall (1999) have opined that only the carabelli cusp (maximum category) provides discrimination between caucasoid and mongoloid groups. in fact, they suggested that the pit and intermediate categories occurred more frequently in mongoloid populations. in this malaysian sample, total frequencies of occurrence of carabelli trait only discriminated chinese from the other three groups but they failed to show any discriminating power for malays, jahai and indians. this result raises doubt about the utility of carabelli trait as a caucasoid marker. the indian sample generally displayed less complex occlusal and palatal surfaces, consistent with tratman’s (1950) anatomical descriptions of his sample, and partially compatible with the caucasoid dental complex (mayhall et al., 1982). from six dental traits proposed by mayhall et al. (1982), only two traits, low prevalence of shovel and high prevalence of hypocone reductions, fit the indian dental characteristics found in this study. the jahai, who represent negritos from the malaysian peninsula, have a similar pattern of dental characteristics as the aetas from the philippines (hanihara, 1992). the similarities noted include low frequencies of shoveling, deflecting wrinkle, and high frequencies of 4-cusped lower second molars. phenetic distances based on dental variations seem to support historical reports. the first documented reports suggest that for a period of time malays lived side by side with orang asli until the “perang sangkel” war broke out between them, causing the orang asli to move deep into the jungle (pusat perkembangan kurikulum, 1998). another documented report is that the malays could have originated from mixture of protomalays (orang asli) with other ethnic groups, such as thailanders, arabs or chinese (nagata, 1979; dentan et al., 2001). unfortunately, our results do not enable us to decide which historical version better explains the close affinity between malays and orang asli. both documented reports generate postulations of potential genetic admixture and sharing of ancestors that could explain the phenetic closeness between the two groups. conclusions most of the dental traits studied showed symmetrical expression in their frequencies of occurrences and low sexual dimorphism. the analyses performed indicated that there are two main groups of malaysians. the mongoloid group comprises malays, negritos (jahai) and chinese, whereas the indian sample can be classified as indo-european. the mongoloid group can be further subdivided, with the jahai and malays fitting the sundadont profile and the chinese conforming to a sinodont profile, as described by turner (1990). phenetic distances based on dental variation lend support to the historical perspectives of malaysian population relationships. 59 literature cited bang g, 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dental anthropology 14:1-8. townsend gc, brown t. 1981. the carabelli trait in australian aboriginal dentition. arch oral biol 26:809-814. townsend gc, yamada h, smith p. 1986. the metaconule in australian aboriginals: an accessory tubercle on maxillary molar teeth. hum biol 58:851-862. townsend gc, yamada h, smith p. 1990. expression of the entoconulid (sixth cusp) on mandibular molar teeth of an australian aboriginal population. am j phys anthropol 82:267-274. tratman ek. 1950. a comparison of the teeth of people. indo-european racial stock with the mongoloid racial stock. dent rec 70:31-53. turner ii cg, hanihara k. 1977. additional features of ainu dentition. v. peopling of the pacific. am j phys anthropol 46:13-24. turner ii cg, scott gr. 1977. dentition of easter islanders. in: dahlberg aa, graber tm, editors. orofacial growth and development. hague: mouton, p 229-249. turner ii cg. 1987. late pleistoceine and holocene population history of east asia based on dental variation. am j phys anthropol 73:305-321. turner ii cg. 1990. major features of sundadonty and sinodonty, including suggestions about east asian microevolution, population history, and late pleistocene relationships with australian aboriginals. am j phys anthropol 82:295-317. turner ii cg, nichol cr, scott gr. 1991. scoring procedure for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larson ls, editors. advances in dental anthropology. new york: wiley-liss, p 13-31. zainuddin r. 2003. sejarah malaysia, 2nd ed. kuala lumpur: fajar bakti. del angel et al. 1993.6 pg13.jpg haeussler 1992.4 pg12.jpg greene 2002.2 10 11 many researchers have determined that the expression of certain dental pathological conditions is not randomly distributed through time among prehistoric humans from the american midwest (e.g., goodman et al., 1984b; sciulli and schneider, 1986; larsen et al., 1991; schmidt, 1998; schmidt and williamson, 1998). rather, these conditions tend to correlate with a population’s diet, density, and degree of sedentism. populations that consumed domesticates such as maize and lived in dense settlements tended to suffer more profoundly from dental caries and disruptions in tooth formation than those who consumed fewer or no domesticates and lived in small groups (powell, 1985). researchers have verified associations between diet and dental disease throughout the world (e.g., enwonwu, 1981; walker and erlandson, 1986; kelly et al., 1991; buikstra, 1992). archeology textbooks that discuss the transition to agriculture tend to ignore the biological record in favor of the more easily defined and recognized social, cultural, and technological transformations (larsen, 1995). however, biological changes are an essential concomitant of lifeway transitions. these biological changes reflect non-specific indicators of diet, health, and workload, and sometimes, more specific indicators such as particular diseases or individual activities. segments of a single population may be affected differentially by adopting agriculture. likewise, populations may experience idiosyncratic biological changes, depending upon their region, the agricultural resource being adopted, and preceding subsistence strategies. in other words, alterations that accompanied agriculture may have been highly localized (larsen, 1995). recent preliminary studies of the ray site, which has been considered by archeologists to be a singlecomponent cemetery, have shown several contradictions to the general rules of small mississippian mortuary sites. differences in the orientation of the graves, positioning of the remains, and inclusion of artifacts may suggest heterogeneity that exceeds typical small mississippian cemeteries. the purpose of this study was to determine whether the skeletal sample is also biologically heterogeneous. since the frequency and expression of dental pathological conditions are known to associate with distinct dietary or settlement patterns, heterogeneity of these conditions within the assemblage would suggest that most heterogeneity is due to representation of more than one population or temporal period. for example primary and secondary interments, which represent different stages in the processing of remains may be seen at many high social status mississippian mortuaries, and could be represented by different burial styles. hypoplastic enamel defects and carious lesions are analyzed to determine whether these conditions vary systematically by grave style or the inclusion of artifacts, thus exposing culturally and/or temporally distinct subgroups. hypoplasia hypoplastic enamel defects include various malformations on the crown surface from furrows to pits that represent episodic disruption of enamel matrix secretion during growth (goodman and armelagos, 1985; goodman and rose, 1991). the surface profile of the tooth is altered due to a convergence of the striae of dental paleopathology of the ray site (12w6), indiana tammy r. greene department of anthropology, university of alaska, fairbanks ak 99775 abstract the ray site (1 2w6), in southern indiana, contains several secondary burials, two of which have been dated to the mississippian period (a.d. 1050-a.d. 1450). three burial styles were noted: (1) burials lined with stone slabs and containing mississippian pottery, (2) burials lined with stone slabs without mississippian pottery, and (3) burials not lined with stone slabs and without mississippian pottery. the purpose of this study was to determine the biological homogeneity of this poorly preserved skeletal assemblage via an analysis of dental pathological conditions, the frequency and expression of which are known to associate with distinct dietary and/or settlement patterns. conditions studied include the frequency of hypoplastic defects and carious lesions, the type of hypoplastic defects, the earliest age of onset of hypoplastic defects, and the location of carious lesions. a total of 437 teeth were scored for hypoplastic defects and 433 were scored for carious lesions. no significant difference in dental pathologies was found between burial styles. therefore, despite considerable burial heterogeneity, dental pathological conditions suggest that individuals from all burials consumed an equally cariogenic diet and underwent similar childhood stresses. it is most likely that all burials are from the same temporal and social group and that the different burial styles represent different stages in the processing of the remains of individuals from a high social status mississippian mortuary. editor’s note: ms. greene’s paper was awarded honorable mention for 2001 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. 10 11 retzius as they approach the enamel surface as well as abnormal prism structure along the defect. because of the appositional nature of enamel, the area of the defect is often overlapped by normal enamel, resulting in locally thin but not necessarily absent enamel (pindborg, 1970; goodman and rose, 1990). many childhood stressors have been linked to hypoplastic enamel defect formation, including vitamin a and d deficiencies, fever, gastroenteritis (goodman et al, 1984a) underand over-nutrition, and hormonal changes (goodman and armelagos, 1985). in fact, most stressors, if severe enough, result in disruptions of enamel development (goodman and rose, 1991), although it is likely that the combination of several stressors is necessary to form a defect. while it may be impossible to distinguish the exact cause of hypoplastic enamel defects, their presence or absence provides insight into the metabolic state of an individual at the time of their dental matrix formation (goodman and rose, 1990). teeth that develop while host resistance is low and environmental insults are high are more likely to have hypoplastic defects (goodman and armelagos, 1985). the presence of a hypoplastic defect on the tooth suggests that the health of the child was sufficient to overcome those environmental insults. hypoplastic enamel defects are found in every native american group and are more frequent in agricultural groups (sciulli, 1978; goodman and rose, 1990). sciulli (1978) presents frequencies of hypoplastic enamel defects for several groups from various time periods: a pre-agricultural group from ohio showed a frequency of 33%; mixed economy groups showed an average of 28.5%; agricultural groups showed frequencies from 43% to 70%. age at which the hypoplastic defect occurs has also been shown to change through time. goodman et al. (1984a) examined two successive prehistoric populations from dickson mounds (a.d. 950-1150, mixed economy; and a.d. 1150-1300, agriculture) in illinois. the former group had a peak frequency between 3.0 and 3.5 years. the latter had a peak frequency between 2.5 and 3.0 years (goodman et al., 1984a). carious lesions carious lesions are among the most frequently reported pathological conditions of the dentition. the lesions are areas of the teeth that have been destroyed by acids produced in dental plaque by bacterial fermentation (heloe and haugejorden, 1981). carious lesions develop under dental plaques, which are dense bacterial masses (gibbons and van houte, 1975). streptococci and gram-positive filamentous bacteria are most often associated carious lesions (gibbons and van houte, 1975). the bacteria feed on the carbohydrates in the mouth producing waste in the form of lactic acid (hillson, 1979). the relationship between diet and carious lesions has been well-established (jacobsen and hansen, 1974; pedersen, 1938; mayhall, 1970; bang and kristoffersen, 1972). it is accepted that increased dependency on foods such as sugars and carbohydrates leads to a higher incidence of carious lesions. increases in carious lesion rates accompanying a dietary shift to greater carbohydrate consumption have been noted in greenland (jacobsen and hansen, 1974; pedersen, 1938), canada (mayhall, 1970), alaska (bang and kristoffersen, 1972), africa (enwonwu, 1981), asia (infirri and barmes, 1979), and europe (corbett and moore, 1976). the location of carious lesions along the tooth row has also been shown to change with subsistence strategies. lesions tend to occur almost exclusively at the cej (cemento-enamel junction) in pre-agricultural populations. foods commonly become lodged around the gum-line. populations that regularly consume refined carbohydrates more often develop carious lesions on the crowns. carbohydrates are sticky and are easily trapped in the grooves in the enamel surface (smith, 1986). frequencies of carious lesions differ among males and females in many geographic locations (lukacs, 1996). however, mississippian sites in the midwest do not tend to show differences between the sexes (smith, 1986). thus foods consumed by males and females are equally cariogenic. the relationship of carious lesion frequency with age is somewhat less established. the angel site, located near and believed to be contemporaneous with the ray site, shows a decrease in carious lesion frequency with age (schmidt, 1998). this decrease may be related to tooth wear. as a tooth wears, there are fewer grooves in which sticky foods may become lodged, thereby reducing the risk of bacterial decay. materials the current study examined mortuary homogeneity in a small late prehistoric mortuary. the ray site (1 2w6) overlooks little pigeon creek near its entry into the ohio river in warrick county, indiana. the ray site is six miles east of the angel site (l2vgl) and one mile north of the yankeetown site (12w1). black (n.d.) first characterized the ray site as yankeetown (a.d. 750 1050). in a reevaluation, ball (1993) suggests that the ray site represents an early angel phase (mississippian period, a.d. 1050-1450) mortuary placed over an earlier yankeetown domestic occupation site. placement of the ray site within the angel phase and its relationship to the angel site are not entirely clear (ball, 1993). the excavations produced eleven prehistoric burials and several intrusive euro-american burials. the euroamerican burials were not examined. three distinct burial classifications can be seen. these include (1) burials with mississippian pottery and stone slabs, (2) burials with stone slabs without mississippian pottery, and (3) burials with no mississippian pottery 12 13 or stone slabs. there are no burials at the ray site with mississippian pottery that do not have stone slabs. the association of burials 7, 8, and 9 with any burial style is unclear (ball, 1993), thus these burials are not considered in the present study. burials 1 and 2 were not collected (black, n.d.). see table 1 for a description of the burials. methods all ray site teeth were first cleaned with a weak ethyl acetate solution to remove the white paint that had been placed on the crowns for labeling in the 1950s. teeth still housed in bony sockets had been covered with the preservative aluvar in the field before removal of the soil. removing the preservative with the ethyl acetate caused minimal damage to the crowns; however, some required reconstruction. teeth that appeared cracked under the preservative were not cleaned and were not included in the study. an inventory of all complete and fragmented teeth from the ray site was taken in order to establish a minimum number of individuals (mni). because of the low occurrence of primary teeth in this sample, they cannot be studied separately and were therefore not examined. table 2 summarizes the inventory of permanent teeth that were included in the study. only permanent teeth with fully formed crowns were scored for hypoplastic enamel defects. permanent teeth that are not fully developed may not yield accurate results. if enamel was missing from the labial side of an anterior tooth or the buccal side of a molar, that tooth was not scored. in order to remain conservative and not score normal variation in perikymata as hypoplastic enamel defects, only those defects that could be seen with the naked eye were scored. all features that were suspected of being hypoplastic after initial examination with the naked eye were then confirmed with a 10x hand lens and fingernail palpation. the leh classification system as presented in buikstra and ubelaker (1994) was used to score the defects. however, due to small sample sizes, it was necessary to collapse the defects into two categories for statistical analysis, namely (a) grooves and (b) pits. table 1. description of burials1 burial mni stone slab? mississippian pottery? 1 unknown shale sandstone pipe 2 unknown none no 3 10 shale, horizontal? yes 4 17 none no 5a 1 shale, vertical no 5b 8 sandstone, vertical no 6 1 none no 7 2 none unknown 8 1 none no 9 unknown none no 10 6 none no 11 1 shale, horizontal no 12 5 shale & sandstone, vertical yes 13 2 none no 1mni (minimum number of individuals) was determined through dental remains. the numbers given in the field notes were based on rough skull counts and therefore may differ from dental counts. table 2. number of teeth available for scoring1 style 1 style 2 style 3 total anterior teeth scored for hypoplastic defects 36 37 88 161 posterior teeth scored for hypoplastic defects 82 35 159 276 total scored for hypoplastic defects 118 72 247 437 anterior teeth scored for carious lesions 35 35 89 159 posterior teeth scored for carious lesions 83 35 156 274 total scored for carious lesions 118 70 245 433 1style 1 refers to those burials with stone slabs and mississippian pottery. style 2 refers to those burials with stone slabs but no mississippian pottery. style 3 refers to those burials with no stone slabs or mississippian pottery. 12 13 age is assigned based on the third of the crown on which the defect occurs. lesions on the cervical-most third are most recent and those on the occlusal-most one-third are the earliest, with each third representing, in general, about 2 years (schour and massler, 1940; massler et al., 1941). this system was used to place the defects into categories of 0-2 years, 2-4 years, 4-6 years, or 6 and over, depending on the developmental timing of the tooth. all erupted permanent teeth were scored for the presence of carious lesions. any tooth that was missing more than 1/4 of the crown due to fracture was not scored. carious lesions were scored according to standards presented by buikstra and ubelaker (1994). due to small sample sizes, lesion location was collapsed into occlusal (including occlusal and smooth surface lesions, including buccal pits and grooves) and cervical (including cervical and interproximal lesions) categories for statistical analysis. because the majority of the teeth in this sample consist of the crown only, root caries were not scored for any tooth. carious lesions were confirmed using a 1ox hand lens. rudney et al. (1983) suggest that visual identification is more reliable than dental probe or radiographic techniques. as suggested by moore and corbett (1971), only those lesions that have penetrated the surface enamel were scored. non-carious pulp exposure (attrition) was also recorded. while attrition is not a pathological condition, it was recorded in order to control for time since eruption of the tooth. wear on molars was scored according to methods presented by scott (1979). teeth receive a score of four, being unworn to polished, to 40, having no remaining enamel. for this study, the median wear score of 11 was used to divide the teeth into categories of high wear and low wear. wear on incisors, canines, and premolars was scored according to methods presented by smith (1984). teeth receive a score of 1, being unworn to polished, to 8, having no remaining enamel. the median wear score of three was used to divide teeth into categories of high wear and low wear. the burial style categories used here include those burials that have stone slabs and mississippian pottery (style 1), those burials that have stone slabs but no pottery (style 2), and those burials that have no stone slabs or pottery or (style 3). small sample sizes did not permit comparisons between each tooth type. therefore, tooth types were collapsed into anterior (incisors, canines and premolars) and posterior (molars) categories. the number of teeth is approximately equal in most categories at the ray site (table 2). however, those burials with stone slabs but no pottery have a significantly greater number of incisors and fewer premolars within the anterior tooth category than the other burial styles. this may potentially bias the number of hypoplastic defects among the anterior teeth of this burial style. analysis of variance (anova) was used to test differences in the numbers of hypoplastic defects and age of occurrence as well as the numbers of carious lesions per tooth between each of the three burial styles. the test examines the effects of the independent variables on the expression of hypoplastic defects or carious lesions (kimble, 1978). all anovas were run on systat for windows version 6.0.1. in addition, to the parametric anovas, nonparametric chi-square tests were used to test the differences in the number of teeth with at least one leh or carious lesion as well as the types of lehs and location of carious lesions. the chi-square tests are goodness-of-fit tests with two degrees of freedom (thomas, 1986). results a total of 437 teeth were scored for hypoplastic defects. the burials with stone slabs and mississippian pottery present (style 1) contained 118 teeth (31% of which have hypoplastic defects) while those with stone slabs but without mississippian pottery (style 2) contained 72 teeth (46% of which have hypoplastic defects). those burials with no stone slabs or mississippian pottery (style 3) contained 247 teeth (25% of which have hypoplastic defects). there is an average of 0.85 defects per tooth in burial style 1, 1.03 defects per tooth in style 2 and 0.82 defects per tooth in style 3. the overwhelming majority of defects in all groups are horizontal linear grooves with very few pits. the earliest age of onset for all groups has a peak frequency between 2 and 4 years. a goodness-of-fit test suggests that there are no significant difference in frequency of affected posterior teeth between the burial styles (table 3). however, burial style 2 has a greater proportion of anterior teeth with at least one hypoplastic defect than the other burial styles. goodness-of-fit tests show no significant difference in the type of hypoplastic defect on the table 4. chi-square statistic for leh type among burial styles n chi-square anterior teeth only 78 6.91* posterior teeth only 57 1.11 *p < 0.05 table 3. chi-square tests for presence of hypoplastic defects among burial styles1 n chi-square anterior teeth only 161 6.74 posterior teeth only 276 3.60 1none was statistically significant. 14 15 posterior teeth (table 4). however, burial style 3 has a greater proportion of pits on the anterior teeth than the other burial styles. significance for these tests and all other tests reported in this paper are based on an alpha of 0.05. anova suggest no significant differences for the number of defects per tooth or earliest age at onset, regardless of tooth type. table 5 summarizes the anova results. a total of 433 teeth were scored for carious lesions. burial style 1 contains 118 teeth (29% of which have carious lesions). burials style 2 contains 70 teeth (30% of which have carious lesions). burial style 3 contains 245 teeth (28% of which have carious lesions). there is an average of 0.86 defects per tooth in burial style 1, 0.90 defects per tooth in burial style 2, and 0.85 defects per tooth in burial style 3. all groups have more occlusal than interproximal lesions. goodness-of-fit tests suggest that there are no significant difference between the burial styles regardless of tooth type or degree of wear (tables 7 and 8). anova suggests that no significant differences exist between the burial styles regardless of tooth type (table 9). discussion overall, hypoplastic defects are very similar among all burial styles represented at the ray site. however, some differences were found. burials with stone slabs but without mississippian pottery (style 3) had a greater proportion of anterior teeth with hypoplastic defects than the other burial styles. however, those burials with stone slabs but without mississippian pottery (style 2) had a substantially larger number of incisors and fewer premolars than the other burial styles. because incisors are more likely to become hypoplastic, it is not surprising that the burial style with more incisors also has more defects. the mean number of hypoplastic defects per tooth does not vary significantly with burial style. this finding suggests that individuals from one burial style did not undergo a greater number of stresses during the time of development than the other burial styles. the earliest age at onset of hypoplastic defects does not vary significantly with burial style. some may argue that given the broad age ranges used, this would reflect the tendency of hypoplastic defects to form on the middle thirds of the crowns (i.e., the age range 2-4 tends to fall the middle third for most teeth). however, the distribution for all age ranges was similar among the burial styles. all burial styles had a peak frequency in the 2-4 year category with the second highest occurrence in the 4-6 year category and the lowest occurrence in the 0-2 year category. this distributions suggest that within each age category, individuals from all burial styles were equally susceptible to hypoplastic defect formation. the type of hypoplastic defect does vary significantly with burial style. burial style 3 has a significantly greater number of pits on the anterior teeth than do the other burial styles. all pits from this burial style are found in a single burial. therefore, the greater number of pits is only representative of one burial, not the burial style as a whole. the pits are also from a minimum of two individuals. therefore, the sample may be biased by a few individuals. it has been suggested that different types of hypoplastic defects (grooves vs. pits) may have different etiologies in some populations (lovell and whyte, 1999). however, there is no evidence in the literature to substantiate this claim. thus the nominal differences seen in hypoplastic defect frequency are most likely biased and to not suggest the presence of two populations at the ray site. comparisons with other sites from known time table 8. chi-square tests for location of carious lesions among burial styles1 n chi-square anterior teeth only 13 1.64 posterior teeth only 115 4.39 high wear only 64 3.91 low wear only 62 2.07 1none was significant statistically. table 7. results of chi-square tests for presence of carious lesions among burial styles1 n chi-square anterior teeth only 159 1.04 posterior teeth only 274 3.28 high wear only 185 0.55 low wear only 248 1.00 1none was significant statistically. table 6. results of anova for earliest age of occurrence for hypoplastic defects among burial styles1 source n f p anterior teeth only 75 1.79 0.17 posterior teeth only 51 0.08 0.92 1none was significant statistically. table 5. results of anova for number of hypoplastic defects per tooth among burial styles1 source n f p anterior teeth only 161 1.25 0.29 posterior teeth only 276 1.56 0.21 1none was significant statistically. 14 15 periods are difficult because most data are given per individual and most teeth from the ray site mortuary could not be reassociated. peak frequencies for age of onset provided for both the late woodland (3.0-3.5 years) and the mississippian (2.5-3.0 years) groups at the dickson mounds (goodman et al., 1984a) are given in half-year age ranges and both fall into the 2-4 year category used in this study. the frequency and expression of carious lesions was very similar for each burial style. the proportion of teeth with at least one carious lesion does not vary significantly based on burial style, regardless of tooth type or degree of wear. the mean number of lesions per tooth does not vary significantly based on burial style, regardless of tooth type or degree of wear. this would suggest that there are no factors, either dietary (e.g., amount of carbohydrates consumed) or biological (e.g., differences in saliva flow or ph) that make the teeth of any one burial style more susceptible to caries. the location of carious lesions does not differ significantly based on burial style, regardless of tooth type or degree of wear. this would suggest that the diets of individuals from each burial style were equally cariogenic. the frequency and expression of carious lesions at the ray site are consistent with other known mississippian period populations. the number of carious lesions per anterior tooth at the ray site is nearly identical to that listed for the kane mounds, a mississippian period site in illinois (milner, 1984). the number of lesions per posterior tooth is also very similar, the only difference occurring when the category is divided into specific tooth types. the second molars of milner’s (1984) sample appear to have a greater number of lesions per tooth than those from the ray site, however this may be due to smaller sample sizes for this tooth at the ray site. thirty-six percent of the posterior teeth of the kane mounds groups have occlusal carious lesions. after correcting for milner’s (1984) scoring method, 33% of the posterior teeth from the ray site have occlusal carious lesions. it appears that all individuals from the ray site mortuary were from the same temporal and social group. the high degree of processing of the remains, the commingled nature of the remains, and the elaborate nature of some of the graves (i.e., stone slabs) suggest that the ray site mortuary contained individuals of higher social status (goldstein, 1980). because there are more stages in processing the higherstatus burials, primary and secondary interments are usually present (goldstein, 1980). it is likely that the different burial styles at the ray site represent different stages in processing the remains of individuals from the same temporal/social group rather than distinct subgroups. because there is no difference in frequency or expression of hypoplastic defects or carious lesions between the burial styles, and the carious lesion data for this site are not inconsistent with known mississippian mortuaries, this study would suggest that all burial styles present at the ray site are indeed associated with the mississippian period. summary and conclusions the purpose of this study was to assess, via an analysis of dental pathological conditions, the biological homogeneity of a small mississippian mortuary with differing burial styles. despite burial heterogeneity, there is no evidence among the dental pathological conditions studied to suggest that more than one population is present in the ray site mortuary. the frequency and expression of hypoplastic defects suggests individuals all burial styles underwent similar childhood stresses. the frequency and expression of carious lesions also suggest that individuals from all burials consumed an equally cariogenic diet. the different burial styles present at the ray site most likely represent different stages in the processing of remains consistent with high social status mississippian mortuaries. future studies should attempt to compare the dental pathological conditions at the ray site with those of other small mississippian high and low status mortuaries in the midwest. acknowledgements the ray site skeletal material is on loan to the university of indianapolis, archeology and forensics laboratory from the indiana university, glenn black laboratory. i would like to thank stephen ball of the glenn black laboratory and christopher schmidt of the university of indianapolis for access to the skeletal material. literature cited ball s. 1993. the ray site: early angel phase mortuary behavior. paper presented at the midwest archaeological conference. bang g, kristoffersen t. 1972. dental caries and diet in an alaskan eskimo population. scand j dent res 80: 440-444. table 9. results of two-way anova for number of carious lesions per tooth among burial styles1 source n f p anterior teeth only burial style 159 0.52 0.60 wear 159 0.06 0.81 style-x-wear 159 1.55 0.21 posterior teeth only burial style 274 2.09 0.13 wear 274 0.26 0.61 style-x-wear 274 1.10 0.33 1none was significant statistically. 16 17 black ga. in press. the yankeetown complex with special reference to the ray site -w6. unpublished manuscript on file at the glenn black laboratory, indiana university, bloomington, indiana. buikstra je. 1992. diet and disease in late prehistory. in: verano jw, ubelaker dh, editors. disease and demography in the americas. washington: smithsonian institution press, p 87-101. buikstra je, ubelaker dh. 1994. standards for data collection from human skeletal remains. arkansas archaeological survey research series no. 44. corbett me, moore wj. 1976. distribution of dental caries in ancient british populations. caries res 10: 401-414. enwonwu co. 1981. review of oral disease in africa and the influence of socio-economic factors. int dent j 31:29-38. gibbons rj, van houte j. 1975. dental caries. annual review of medicine: selected topics in clinical sciences. 26:121-136 goldstein lg. 1980. mississippian mortuary practices: a case study of two cemeteries in the lower illinois valley. evanston, illinois: northwestern university archeological program. goodman ah, armelagos gj. 1985. factors affecting the distribution of enamel hypoplasias within the human permanent dentition. am j phys anthropol 68:479-493. goodman ah, armelagos gj, rose jc. 1984a. chronological distribution enamel hypoplasias from prehistoric dickson mounds populations. am j phys anthropol 65:259-266. goodman ah, lallo j, armelagos gj, rose jc. 1984b. health changes at dickson mounds, illinois (a.d. 950-1300). in: cohen mn, armelagos gj, editors. paleopathology at the origins of agriculture. orlando: academic press, inc. p 271-305. goodman ah, rose jc. 1990. assessment of systemic physiological perturbations from dental enamel hypoplasias and associated histological structures. yearbook phys anthropol 33:59-110. goodman ah, rose jc. 1991. dental enamel hypoplasias as indicators of nutritional status. in: kelly ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p 279-293. heloe la, haugejorden 0. 1981. the rise and fall of dental caries: some global aspects of dental caries epidemiology. oral epidem 9:294-299. hillson sw. 1979. diet and dental disease. world archeol 11:147-162. infirri js, barmes de. 1979. epidemiology of oral diseases: differences in national problems. int dent j 29:183-190. jacobsen j, hansen er. 1974. cariessituationen i gronland 1973/74. tandlaegebladet 78:839-847. kelley ma, levesque dr, weidl b. 1991. contrasting patterns of dental disease in five early northern chilean groups. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p 203-213. kimble ga. 1978. how to use and misuse statistics. englewood cliffs, new jersey: prentice-hall, inc. larsen cs. 1995. bioarchaeology: interpreting behavior from the human skeleton. cambridge, united kingdom: cambridge university press. larsen cs, shavit r, griffin mc. 1991. dental caries evidence for dietary change: an archaeological context. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p 179-202. lukacs jr. 1996. sex differences in dental caries rates with the origin of agriculture in south asia. curr anthrop 37:147-153. massler m, schour i, poncher hg. 1941. developmental pattern of the child as reflected in the calcification pattern of the teeth. am j dis child 62:33-67. mayhall jt. 1970. effect of culture change upon the eskimo dentition. arctic anthrop 7:117-121. milner gr. 1984. dental caries in the permanent dentition of a mississippian period population from the american midwest. coll antropol 1:77-91. moore wj, corbett me. 1971. the distribution of dental caries in ancient british populations. caries res 5: 151-168. pedersen p0. 1938. meddelelser om odontologiske undersogelser pa grønland. tandlaegebladet 42: 127-157. pindborg jj. 1970. pathology of dental hard tissue. philadelphia: wb saunders company. powell ml. 1985. the analysis of dental wear and caries for dietary reconstruction. in: gilbert jr. ri, mielke jh, editors. the analysis of prehistoric diets. orlando: academic press, p 307-338. rudney jd, katz rv, brand jw. 1983. interobserver reliability of methods for paleopathological diagnosis of dental caries. am j phys anthropol 62: 243-248. schmidt cw. 1998. dietary reconstruction among prehistoric humans from indiana: an analysis of dental macrowear, dental pathology, and dental microwear. ph.d. dissertation, purdue university. schmidt cw, williamson ma. 1998. paleopathology at the late woodland albee phase, commissary site (12hn2): implications for sedentism and maize consumption. indiana arch 2:43-69. schour i, massler m. 1940. studies in tooth development: the growth pattern of human teeth ii. j am dent assoc 27:1918-1931. sciulli pw. 1978. developmental abnormalities of the permanent dentition in prehistoric ohio valley amerindians. am j phys anthropol 48:193-198. sciulli pw, schneider kn. 1986. dental caries and horticulture in prehistoric ohio. penn arch 56:2128. 16 17 scott ec. 1979. dental wear scoring technique. am j phys anthropol 51:213-218. smith bh. 1984. patterns of molar wear in huntergatherers and agriculturalists. am j phys anthropol 63:39-56. smith mo. 1986. caries frequency and distribution in the dallas skeletal remains from toqua (40mr6), monroe county, tennessee. tennessee anthropol 11:145-155. thomas dh. 1986. refiguring anthropology: first principles of probability and statistics. prospect height, illinois: waveland press, inc. walker pl, erlandson j. 1986. dental evidence for prehistoric dietary change on the northern channel islands. am antiq 51:375-383. spread the word have you developed a web-site relevant to dental anthropology? please let us know if have webbased information about dental anatomy, forensic dentistry, dental trait variation, a novel statistical approach—or almost anything else relevant to the readers of dental anthropology. let us know, and we’ll publicize the site. send the location of the site and supply a short description of its purpose and content. e-mail your information to the editor: eharris@utmem.edu. scott 1996.7 pg22.jpg pg23.jpg lincoln-babb 1995.3 pg10.jpg pg11.jpg pg12.jpg lukacs 1992.2 pg3.jpg pg4.jpg pg5.jpg pg6.jpg pg7.jpg pg8.jpg becker 1995.3 pg8.jpg pg9.jpg mucic and duric-srejic 1996.2 pg7.jpg pg8.jpg pg9.jpg pg10.jpg periera et al. 1994.2 pg8.jpg pg9.jpg pg10.jpg fong and sturges 1992.4 pg11.jpg brace 1994.1 pg2.jpg pg3.jpg becker 1994b.2 pg5.jpg pg6.jpg pg7.jpg pg8.jpg pg9.jpg pg10.jpg irish and hemphill 2004.2 8 9 the canary islands are located in the atlantic ocean off the northwest coast of africa (fig. 1). seven small islands comprise the archipelago: la palma, gomera, hierro, tenerife, grand canaria, fuerteventura, and lanzarote. of the seven islands, fuerteventura is nearest the continent, approximately 100 km west of cape juby, morocco. the canary islands have been a part of spain since the late 15th century. however, prior to that time they were occupied by the guanche—the aboriginal inhabitants of the archipelago. these early people were primarily cereal agriculturalists who practiced a neolithic lifestyle (cavalli-sforza et al., 1994). they possessed domesticated goats and pigs, and supplemented their diet with shellfish, fish, and various wild plants (mercer, 1980). an odontometric investigation of canary islander origins address for correspondence: joel d. irish, department of anthropology, p.o. box 757720, university of alaska fairbanks, fairbanks, ak 99775-7720, u.s.a. e-mail: ffjdi@uaf.edu joel d. irish* and brian e. hemphill** *department of anthropology, university of alaska, fairbanks, ak 99775. **department of sociology & anthropology, california state university, bakersfield, ca 93311 abstract attempts by anthropologists to account for the peopling of the canary islands have led to theories that call for one, two, and even four immigration events. however, most agree the canary island guanche are biologically closest to berbers from morocco and algeria. genetic contributions from arabs, romans, and carthaginians have also been proposed. an earlier study by irish using penrose analysis of odontometric data in samples of guanche, shawia and kabyle berbers, and bedouin arabs supports many of these proposed genetic relationships. the present investigation expands upon this earlier work by adding samples of carthaginians, egyptians, and nubians, and by using tooth size apportionment analysis, a more robust statistical approach for assessing inter-sample differences in the distribution, or allocation, of tooth size in the maxillary and mandibular dental arcades. the analysis yielded three components that account for >80% of the total variance. cluster analysis and three-dimensional ordination of group component scores provide additional insight into canary island/north african relationships. except for one early nubian sample, the guanche exhibit some measure of affinity to all others. however, they are most like berbers and carthaginians. these results suggest that canary islanders belong to a greater north african gene pool, yet show the closest affinities to northwest africans—which corroborates earlier dental and nondental findings. dental anthropology 2004;17:8-17. authors’ note: a preliminary version of this paper was included in the 2001 volume la paléo-odontologie: analyses et méthodes d’étude, paris: éditions artcom, edited by djillali hadjouis and bertrand mafart. that article (irish and hemphill, 2001) was published in french, is generally not available outside of western europe, and contained several publisher errors in the tables and figures. as such, we decided to provide a modified and expanded english translation to facilitate dissemination of our findings to a wider audience of dental and canary island researchers. over the past 100 years, numerous researchers have attempted to determine the origins and biological affinities of the guanche (e.g., verneau 1887, 1891; hooton 1916, 1925; falkenburger 1939; fusté 1959, 1965; schwidetzky 1963; roberts et al., 1966; vallois 1969; mercer 1980; gonzalez and tejera, 1981; onrubia pintado, 1987; bermudez de castro, 1989). as a result, the original guanche homeland has alternately been identified as africa, europe, and/or the eastern mediterranean area. the purpose of the present investigation is to reexamine four of these origins hypotheses using evidence from principal components analysis of odontometric data in canary island, north african, and west asian-derived samples. although other theories exist (see vallois 1969 for an overview), the four examined here afford a representative sampling of those envisioned by all researchers. components obtained from statistical analyses yield information on overall crown size, as well as the allocation of size across dimensions and tooth types in both jaws among samples. this approach, termed tooth size apportionment analysis (see harris and bailit, 1988; harris and rathbun, 1991; lukacs and hemphill, 1993), 8 9 african mainland during the neolithic. these two groups consisted of “cro-magnoid” and “mediterranean-like” cranial types, asserted to be evident in prehistoric guanche remains. these same findings are echoed by fusté (1959, 1965), vallois (1969), and others. the former cranial type is said to be characterized by a wide low face with robust features, whereas the latter is more gracile with a narrow, high face. roberts and coworkers (1966) proposed that the guanche were the product of an ancient colonization from europe (which reprises verneau’s thesis to some extent (see vallois 1969)). they based their conclusions on perceived osteological affinities of ancient guanche skeletons (per hooton, 1925; hiernaux, 1975) and serological and dermatoglyphic affinities of living canary islanders (mourant, 1954; roberts et al., 1966) to northwest europeans. lastly, mercer (1980) described an immigration of northwest african berbers during the roman era, based on 15th-17th century ethnographic accounts of guanche oral traditions and paleo-serological analyses of guanche mummies. he suggested that berber malcontents from the atlas mountains of northern morocco and algeria were exiled to the islands as punishment for resistance to roman rule. mercer also sees a lack of definite radiocarbon dates prior to the first century ad in the archipelago as supportive of this canary islander odontometrics is intended to provide new insight into the old problem of understanding guanche ancestry. previous peopling hypotheses hooton (1916, 1925) was one of several early anthropological researchers to investigate the origins and population history of canary islanders (see also verneau 1887, 1891, and among others, quatrefages and hamy 1874, shrubsall 1896, von luschan 1896, von behr 1908 (as presented in vallois 1969)). he hypothesized that four migrations to the islands from north africa took place during the neolithic and bronze age. based on the analyses of craniometric and ethnographic data, hooton maintained that the guanche were comprised of different stocks of people largely exhibiting mediterranean and alpine caucasoid components, supplemented perhaps, by sub-saharan and other elements. he further proposed that they originated from populations inhabiting southern morocco, the atlas mountains of northern morocco and algeria, and the eastern mediterranean (fig. 1). subsequent intermixture among these four groups, along with later arab, berber, and carthaginian gene flow, was thought to have resulted in the pre-european contact peoples of the canary islands. based on cranial morphometric data, schwidetzky (1963) envisioned two migrations from the adjacent fig. 1. regional map showing canary islands, north africa, and the mediterranean area. 10 11 late-arrival model. in addition, his hypothesis provides an explanation for sea transportation to the islands—an ability the guanche apparently did not possess at the time of european contact. however, others maintain (e.g., cavalli-sforza et al., 1994) that the guanche originally sailed to the islands of their own accord, and subsequently lost the skill to make adequate sea-going vessels. like hooton, mercer suggests later contact by carthaginians and arabs may have provided an additional genetic contribution to the canary island gene pool. despite these widely varying scenarios all workers agree that, at the time of european contact, the native guanche comprised a lightly-pigmented population (murdock, 1959; vallois, 1969) reminiscent of peoples living throughout europe, the mediterranean area, and parts of north africa. this contention is based on 15th century french and spanish accounts, in addition to the aforementioned ethnographic, serological, skeletal, and other data. further, excluding roberts et al. (1966), most researchers believe the guanche were closely related to northwest african berbers (see hooton, 1916; schwidetzky, 1963; gonzalez and tejera, 1981; onrubia pintado, 1987; bermudez de castro, 1989); perhaps those from the atlas mountains region of northern morocco and algeria (mercer, 1980). support for this relationship is bolstered by recent genetic analyses (cavalli-sforza et al., 1994), as well as long-standing linguistic evidence that guanche, the canary islander’s extinct language (bynon, 1970), shows a close affinity to the afroasiatic berber language (hooton, 1916, 1925; greenberg, 1966; mercer, 1980). the berber language may in turn be derived from the late paleolithic north african mechta and capsian cultures (hiernaux, 1975; mercer, 1980; onrubia pintado, 1987). however, as hooton (1925) and mercer (1980) note, the islands’ population may have also been influenced by arab, roman, and carthaginian contact prior to the 15th century spanish occupation. odontometric analyses in a preliminary study (irish, 1993a), aspects of the four hypotheses were tested via penrose shape analysis of tooth crown diameters in samples of pre-european contact canary islanders (n=163), and historic northwest african shawia berbers (n=26), kabyle berbers (n=32), and bedouin arabs (n=49). although metric data are employed, the penrose shape component is analogous to morphological analysis because it emphasizes differences in the form of a structure (crown form) rather than size (penrose, 1954; rahman, 1962; corruccini, 1973). the results tentatively support a canary island/northwest africa link. the guanche comparison to the shawia and kabyle berbers yielded low, insignificant shape values (0.09 and 0.10, respectively), indicating a close phenetic similarity that would be expected if berbers colonized the islands. the magnitude of the guanche/ arab value is twice that of the other comparisons (0.18) and is significant (rahman, 1962), suggesting a more distant affinity. the present investigation expands upon this previous odontometric study. besides the guanche, berbers, and arabs, samples of west asian-derived carthaginians and northeast african egyptians and nubians are added. in total, 12 prehistoric through historic northwest and northeast african samples, comprising 669 dentitions, are analyzed and compared. moreover, in place of penrose, tooth size apportionment analysis (harris and bailit, 1988; harris and rathbun, 1991; lukacs and hemphill, 1993) is used on the odontometric data. this technique provides a more robust statistical approach that uses principal components analysis for assessing inter-sample differences in allocation of tooth size. materials and methods the samples the canary islands sample used in both the previous and present odontometric studies consists of 163 skeletal dentitions (male=70, female=52, indeterminate=41). eight crania are from the island of la palma, 25 from gomera, 54 from tenerife, 56 from gran canaria, 11 from fuerteventura, and nine from unidentified locations in the archipelago. most specimens are curated at the musée de l’homme, paris, although 13 are located at the american museum of natural history, new york, and two are at the national museum of natural history in washington, d.c. the exact date(s) of the series is unknown, but radiocarbon dating of grottoes, caves, and tumuli similar to those from which the present materials were removed range from 20 bc to ad 1690+70, with a median range of ad 400-900 (mercer, 1980; bermudez de castro, 1989). the shawia berber sample consists of 26 historic individuals who originally lived just south of constantine, algeria (see fig. 1). the sample consists of dentitions from 16 males, seven females, and three individuals of unknown sex, all from the musée de l’homme. greenberg (1966) characterizes berbers as speaking one of several dialects (e.g., shawia) of the berber language, which belongs to the berber language family in the afroasiatic superfamily. their language also reflects influence from phoenician, latin, and arabic sources (bynon, 1970). such heterogeneity is consistent with the fact that berber populations, especially those from the less-mountainous regions of algeria and morocco, show evidence of admixture with arabs and other intrusive peoples (i.e., carthaginian, greek, roman, spanish, turkish, french) (wysner, 1945). the kabyle berber sample is made up of 32 historic crania (male=21, female=7, indeterminate=4) from the algiers and oran region of the djurdjura mountains in northern algeria (wysner, 1945). they are all curated at the musée de l’homme. unlike many berbers, the kabyle remained isolated from the many outsiders who successively conquered lands throughout northern africa j.d. irish and b.e. hemphill 10 11 beginning in 750 bc. as such, they experienced relatively little genetic admixture (wysner, 1945). the berbers may be indigenous to north africa, being descended from earlier capsian and perhaps mechta peoples (hiernaux, 1975; irish, 1998a,b, 1999, 2000). the bedouin arab sample (n=49) is composed of a heterogeneous mix of historic crania (male=18, female=24, indeterminate=7). thirty-six individuals were recovered from the coast of morocco between rabat and mogador, ten are from algeria between oran and algiers, two are from tunis, tunisia, and one is from the sahel region of libya. the latter specimen was recorded at the university of minnesota; the rest are at the musée de l’homme. arabs first entered africa along the suez isthmus in the 7th century, conquering byzantine lands in egypt and to the west. a second wave of arabs arrived in the 11th century, when entire tribes of bedouin immigrated from the syrian desert (julien, 1970; hiernaux, 1975). these nomadic peoples are similar in physical appearance to the berbers with whom they are heavily admixed (julien, 1970; hiernaux, 1975). the carthaginian sample is made up of 28 individuals (male=16, female=8, indeterminate=4) from the site of carthage, north of tunis, tunisia. twenty-four crania were recovered from punic period levels (751?-146 bc) (charles-picard and picard, 1968). the four remaining skulls may be from the punic period, or are perhaps from early roman times (146 bc-ad 435) (wysner, 1945). all of the material is curated at the musée de l’homme. carthage was founded in ca. 751 bc by the phoenicians, a west asiatic people from the area now comprising lebanon (charles-picard and picard, 1968). in 146 bc, carthage was conquered by the romans, who remained in control until ad 435. both the carthaginians and romans are thought to have had extensive contact with local berber populations (wysner, 1945). the remaining seven samples, from northeast africa, are included in the dental analysis to help delineate guanche affinities on a broader, geographically-oriented scale. three samples comprise 12th dynasty through byzantine egyptians (1991 bc-ad 600) (elliot smith and wood-jones, 1910; baines and malek, 1982) from lisht (n=61), el hesa (n=72), and kharga oasis (n=26) in egypt. the specimens are located at the american museum of natural history and national museum of natural history. there are several hypotheses concerning egyptian origins; they may be non-african (i.e., west asian or southern european) (angel, 1972; curto, 1972; hiernaux, 1975; mourant, 1983), an admixed people, with african and non-african roots (e.g., hamid zayed, 1981), or indigenous (white, 1970; davidson, 1974; trigger, 1976; july, 1992; phillipson, 1994; newman, 1995; williams, 1997). whichever the case, by the dynastic period they were likely a heterogeneous people from the combining of many ethnic elements (curto, 1972; davidson, 1974). the other four northeast samples are from nubia, in northern sudan. one sample consists of 18th dynasty pharonic nubians (1575-1380 bc) (trigger, 1976) from soleb (n=32); the others are meroitic (n=91), x-group (n=39), and christian (n=18) nubians (100 bc-ad 1400) from semna (zabkar and zabkar, 1982) (see irish, 1993b, 1998b for a more complete description of all samples). the pharonic sample was recorded at the musée de l’homme; the others are curated at arizona state university, tempe. the origin of the nubians is unclear; they may be locals that possess a sub-saharan component (e.g., greene, 1967, 1972; carlson and van gerven, 1977, 1979), or are heavilyadmixed migrants from elsewhere in north africa (irish and turner, 1990; turner and markowitz, 1990). methods employed mesiodistal and buccolingual dental crown measurements were taken by irish on each individual’s maxillary and mandibular permanent teeth (i1-m3), following the method of moorrees (1957), with boley gauge vernier calipers accurate to 0.1 mm. excessively worn or carious teeth, as well as those antimere pairs exhibiting obvious size asymmetry (most often m3s), were not measured. the degree of intra-observer measurement error was assessed by comparing replicate measurements of the left side of 25 meroitic dentitions. the mean measurement error between sessions one month apart is 0.2 mm; this figure is within the range noted by wolpoff (1971). moreover, none of the measurements are significantly different based on paired-sample t-tests. dimensions of teeth on the left side in each sample were used for statistical analysis because, based on paired-sample t-tests, no significant differences occurred between antimeres for any dimensions (per hemphill, 1991; hemphill et al., 1992; lukacs and hemphill, 1993). if a significant difference (p < 0.05) would have existed, the average of the dimensions from the antimere pairs would have been used per individual to compute the sample average. in cases where a tooth on the left side was missing in an individual, the right antimere (if present) was measured to maximize sample size. the resulting 32 or fewer mesiodistal and buccolingual dental crown measurements per individual were then used to calculate mean crown diameters for use in the assessment of odontometric affinity among samples. tooth size apportionment analysis was conducted according to the procedures of harris and bailit (1988) and harris and rathbun (1991), as modified by hemphill (1991). the covariance matrix of mean crown diameters for each of the 12 samples was submitted to principal components analysis to obtain component loadings. crown diameters for each sample were multiplied by the loadings for each tooth diameter, and this product was summed across all 32 crown diameters. this methodology yielded three component scores per sample (see lukacs and hemphill, 1993). the mean total crown area (md x bl) for all 16 teeth, canary islander odontometrics 12 13 per sample, was used to assess differences in overall tooth size. if samples differed significantly in total crown area (>5%), residual component scores were calculated for those components significantly correlated with overall tooth size. group component scores were then submitted to cluster analysis and three-dimensional ordination. a minimum spanning tree (hartigan, 1975) was imposed on the array of component scores for ease of interpretation of association among the individual samples. all statistical analyses were performed with systat statistical software (wilkinson, 1990). ideally, odontometric research should involve separate analyses by sex. however, out of necessity, the sexes were pooled by sample in this study. this approach follows the lead of harris and rathbun (1991), and lukacs and hemphill (1991), who report that any dental size variation between the sexes was not great enough to justify the markedly smaller sample sizes. moreover, hemphill et al. (1992) and lukacs and hemphill (1993) found that while males and females within an ethnic group differ in absolute tooth size, apportionment of tooth size is unaffected by sex dimorphism. results tooth size apportionment analysis of the 12 samples’ crown measurements yielded the component loadings in table 1; component eigenvalues and percentage of the variance explained are also tabulated. the dental crown measurements themselves will be presented in a separate publication on african odontometric variation, and thus are not listed. although six principal components possess eigenvalues greater than 1.0, the first three alone account for 80.4% of the total variance. component one is dominated by a general size factor, which is illustrated by the strong positive loadings for most variables (see top of fig. 2). nevertheless, a second factor involving relative dimensions of the teeth is also evident, as reflected by much lower loadings for buccolingual dimensions of the maxillary and, particularly, mandibular anterior teeth. in other words, high scorers along this component are characterized by generally large dentitions, with anterior teeth that exhibit long mesiodistal relative to narrow buccolingual diameters. the second component separates samples on the basis of two criteria (see middle of fig. 2). the first is similar to the secondary factor of component one. anterior teeth (i1, i2, c) feature dimensional segregation, with buccolingual breadths receiving higher loadings than mesiodistal lengths; this is true for both maxillary and, especially, mandibular teeth. the second distinction involves the distal molars (m2, m3). mandibular mesiodistal and buccolingual diameters receive fewer negative loadings than their maxillary counterparts. this difference is slightly greater for the mesiodistal than buccolingual dimensions. thus, high scorers along component two exhibit broad buccolingual diameters among anterior maxillary and, especially, mandibular teeth relative to mesiodistal dimensions, as well as relatively large mandibular distal molars compared to their maxillary isomeres. the loadings for component three are, at first glance, confusing. however, there appears to be a distinction in buccolingual dimensions by isomere; that is, with the exception of p4 and m2, maxillary breadths receive higher loadings than their mandibular counterparts (see bottom of fig. 2). this is especially true for i1 and c. thus, high scorers for component three possess maxillary teeth that are broader in their buccolingual j.d. irish and b.e. hemphill components variable 1 2 3 ui1md 0.837 0.078 0.151 ui1bl 0.377 0.631 0.606 ui2md 0.960 -0.102 0.090 ui2bl 0.724 0.263 0.043 ucmd 0.563 0.570 0.332 ucbl 0.491 0.642 0.280 up3md 0.952 0.021 0.076 up3bl 0.911 -0.056 0.232 up4md 0.730 -0.057 -0.424 up4bl 0.923 -0.089 0.081 um1md 0.774 -0.066 -0.425 umibl 0.909 0.044 0.198 um2md 0.777 -0.371 -0.312 um2bl 0.770 -0.325 -0.312 um3md 0.499 -0.661 0.428 um3bl 0.802 -0.485 0.008 li1md 0.737 0.175 0.235 li1bl 0.177 0.497 -0.511 li2md 0.833 0.216 0.149 li2bl 0.177 0.850 -0.161 lcmd 0.807 0.252 -0.340 lcbl 0.347 0.765 -0.347 lp3md 0.817 -0.343 -0.010 lp3bl 0.817 -0.129 0.358 lp4md 0.847 0.051 -0.257 lp4bl 0.933 0.040 -0.123 lmimd 0.844 -0.034 0.207 lm1131 0.927 0.100 -0.023 lm2md 0.917 0.055 -0.150 lm2bl 0.895 -0.035 -0.254 lm3md 0.781 -0.222 0.207 lm3bl 0.837 0.275 -0.094 eigenvalue 19.147 4.133 2.462 variance (%) 59.834 12.916 7.695 total variance 80.445 table 1. component loadings, eigenvalues, and variance explained for the 12 dental samples. 12 13 dimensions than the corresponding mandibular isomeres. once component loadings were obtained, total crown areas by sample were regressed on component scores to determine if overall tooth size represents a significant contributing factor behind group scores. as is often the case, component one scores are highly associated with size (see table 2)—in this case overall tooth size (f=1537.84, p=0.00). however, components two and three do not show a significant association. to compensate for the effect of overall tooth size, the regression formula was used to obtain expected component one scores. expected scores were subtracted from the observed to calculate group departures (residuals) from expected results from general tooth size. the next step in analysis requires the use of some technique to illustrate the patterning of biological distances delineated by the residual component one, component two, and component three scores (table 2). in the present investigation four methods of cluster analysis—complete linkage, single linkage, average linkage, and ward’s minimum variance, as well as three-dimensional ordination were employed. the complete linkage dendrogram is presented in figure 3. results obtained with other associating algorithms produced analogous results. the guanche sample is phenetically most similar to northwest african shawia berbers, a relationship revealed by the previous penrose analysis (irish, 1993a). the guanche also show a close affinity to the carthaginian and kabyle samples. members of this four-group aggregate share anterior teeth of intermediate buccolingual size, and maxillary and mandibular isomeres of proportionate dimensions. the guanche are next most-like the aggregate at the center of the dendrogram that contains christian, xgroup, and meroitic nubians, lisht, el hesa, and kharga egyptians, and bedouin arabs. the earlier penrose analysis (irish, 1993a) also showed the arab sample fig. 2. loadings among the 12 dental samples for components one, two, and three. canary islander odontometrics sample tca comp1 rcmp1 comp2 comp3 guanche 1098.09 -0.399 -0.185 0.150 -0.377 shawia 1100.64 -0.164 0.002 0.820 -0.112 kabyle 1117.97 0.125 -0.038 2.001 -0.654 bedouin 1084.59 -0.457 0.014 -0.489 0.659 carthage 1058.07 -1.058 -0.084 0.931 -1.394 lisht 1050.73 -1.191 -0.077 -0.730 0.110 el hesa 1051.15 -1.130 -0.024 -0.701 0.865 kharga 1086.70 -0.624 -0.194 -0.508 0.983 soleb 1193.56 1.566 -0.043 1.176 2.012 meroitic 1145.27 0.750 0.068 -0.746 0.009 x-group 1191.73 1.431 -0.134 -1.239 -0.883 christian 1177.20 1.162 -0.127 -0.664 -1.218 table 2. total crown area (tca), component scores (comp), and residuals (rcmp) for the 12 dental samples. 14 15 to be slightly divergent from the guanche. moreover, except for the west asian-derived arabs who, as noted comprise a mix of individuals from throughout north africa, this seven-group aggregate is composed entirely of northeast africans. for the most part, these samples exhibit a tendency toward broad maxillary teeth relative to the corresponding mandibular isomeres. this pattern is particularly evident in the christian and x-group nubian samples; they also possess relatively large teeth (see tca in table 2). lastly, the guanche, as well as all other samples, are most divergent from pharonic nubians from soleb. the soleb sample is characterized by the largest teeth of all samples, as well as broad buccolingual anterior tooth diameters and large mandibular molars relative to the maxillary counterparts. similar dental relationships are illustrated by ordination of the three principal component scores (figure 4). axes x, y, and z correspond to the sample scores for residual component one (rcmp1), component two (comp2), and component three (comp3). the guanche (can), located on the far left of the figure, link most closely with northwest africans; that is, fig. 4. three-dimensional ordination with minimum spanning tree of principal component scores among the 12 samples. see text for explanation of abbreviations. fig. 3. complete linkage cluster analysis dendrogram of principal component scores among the 12 samples. j.d. irish and b.e. hemphill 14 15 with carthaginians (car), shawia berbers (alg), and kabyle berbers (kab). however, they also exhibit some affinities to northeast africans. this affinity is evident by the guanche connection to the meroitic sample (mer) from semna. meroitic nubians are in turn linked to x-group (xgr) and christian (chr) nubians, and to lisht (lis), the bedouin arabs (bed), el hesa (hes), kharga (kha), and the soleb (sol) outlier, respectively. discussion and conclusions although the timing and circumstances under which the immigration event(s) occurred have not been addressed by these odontometric results, tooth size apportionment analysis has revealed two important findings that pertain to other aspects of the four peopling hypotheses. first, the canary island guanche show closest dental affinities to northwest africans, relative to other samples of various ages. second, the pattern of phenetic affinities possessed by the guanche suggest that some degree of biological relatedness extends beyond the adjacent mainland to nubians and egyptians in northeast africa. the guanche share a very similar pattern of tooth size apportionment with the shawia and, to a lesser extent, kabyle berbers. this similarity corroborates results of a preliminary odontometric study (irish, 1993a), and supports those aspects of hooton’s (1916, 1925), schwidetzky’s (1963), and other’s (e.g., fusté 1959, 1965; vallois 1969) models that suggest at least some guanche originated in northwest africa; it specifically sustains mercer’s (1980) and other’s (e.g., gonzalez and tejera, 1981; onrubia pintado, 1987; bermudez de castro, 1989; cavalli-sforza et al., 1994) claims for a sole berber ancestry from populations living in northern morocco and algeria. conversely, this finding cannot completely rule out hooton’s (1925), schwidetzky’s (1963), and other’s (e.g., fusté 1959, 1965; vallois 1969, etc.) evidence for some eastern mediterranean input, considering the guanche affinity to most northeast africans. moreover, guanche similarity to west asian-derived carthaginians could be interpreted as support for this contention. however, such an affinity may simply identify evidence for berber/carthaginian admixture, or could imply genetic relatedness via the latter’s proposed direct contact (hooton, 1916, 1925; mercer, 1980) with the guanche; a similar situation might explain the slightly more distant guanche affinity to west asian-derived bedouin arabs. in addition, hooton’s (1925) suggestion for a subsaharan genetic component has not been directly tested here, although data from dental morphological studies (see irish, 1993b, 1997, 1998a,b, 2000) do not support such a relationship. whatever the case, the concordance of skeletal, ethnographic, linguistic, genetic, and now dental data, should put to rest any notion of a nonafrican (i.e., european) origin for aboriginal canary islanders (as per roberts et al., 1966). the evidence for a lesser guanche affinity to egyptian and three of four nubian samples implies aboriginal canary islanders belong to a greater north african gene pool. some level of diachronic dental homogeneity apparently exists throughout north africa—from the canary islands to egypt and northern sudan. indeed, this east-west similarity suggests that a clinal relationship in tooth size apportionment existed, considering the separation of northwest and northeast african samples. these conclusions support previous findings based on dental morphological analyses published elsewhere (irish, 1993b, 1997, 1998a,b; guatelli-steinberg et al., 2001). acknowledgments we thank the individuals at the institutions from which the guanche and comparative data were collected, including: christy g. turner ii, charles merbs, and donald morris from arizona state university; guy gibbon and the late elden johnson from the university of minnesota; douglas ubelaker and david hunt from the national museum of natural history; ian tattersall, jaymie brauer, and gary sawyer from the american museum of natural history; andre langaney, frances roville-sausse, and miya awazu periera da silva from the musée de l’homme; fred wendorf and sue linder-linsley from southern methodist university, and henry de lumley and 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new york: wiley-liss, p 77-119. lukacs jr, hemphill be. 1993. odontometry and j.d. irish and b.e. hemphill 16 17 biological affinity in south asia: analysis of three ethnic groups from northwest india. hum biol 65: 279-325. mercer j. 1980. the canary islanders: their prehistory, conquest and survival. london: rex collings. moorrees cfa. 1957. the aleut dentition: a correlative study of dental characteristics in an eskimoid people. cambridge: harvard university press. mourant ae. 1954. the distribution of the human blood groups. springfield, il: charles c. thomas, publisher. mourant ae. 1983. blood relations: blood groups and anthropology. oxford: oxford university press. murdock gp. 1959. africa: its peoples and their culture history. new york: mcgraw-hill. newman jl (1995) the peopling of africa: a geographic interpretation. new haven: yale university press. onrubia pintado j. 1987. les cultures préhistoriques des îles canaries état de la questions. l’anthropologie 91:653-678. penrose 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canarien. archives des missions scientifieques et littéraires, 3e série 13:569-817. verneau r. 1891. cinq années de séjour aux îles canaries. paris. white jem. 1970. ancient egypt: its culture and history. new york: dover publications, inc. williams b. 1997. egypt and sub-saharan africa: their interaction. in: vogel j, editor. encyclopedia of precolonial africa: archaeology, history, languages, cultures, and environments. walnut creek: alta mira press, p 465-472. wilkinson l. 1990. systat: the system for statistics. evanston, il: systat, inc. wolpoff mh. 1971. metric trends in hominid dental evolution. studies in anthropology, no. 2. cleveland: case western reserve university press. wysner gm. 1945. the kabyle people. new york: privately printed. zabkar lv, zabkar j. 1982. semna south. a preliminary report of the 1966-68 excavation of the university of chicago oriental institute expedition to sudanese nubia. j am res center egypt 19:21-28. canary islander odontometrics winkler and swindler 1993.5 pg9.jpg pg10.jpg burnett 1996.3 segeda 1993.2 pg5.jpg pg6.jpg pg7.jpg turner 1993.4 pg10.jpg pg11.jpg hildebolt et al. 1993.3 pg14.jpg pg15.jpg pg16.jpg pg17.jpg pg18.jpg turner 1991.1 pg4.jpg pg5.jpg watson 2017.4 38 dental anthropology 2017 │ volume 30 │ issue 01 as some of the most durable tissues of the skeleton, teeth are often better preserved than much of the rest of the body and represent more common fossil finds at paleoanthropological sites. in addition, they provide a plethora of information about biological or phylogenetic relationships, dietary reconstruction, growth and development, and decay. “what teeth reveal about human evolution” is an accessible account of what we can, and have, learned from studying teeth across the fossil and skeletal record of our hominin ancestors. writing in a friendly and personal style, debbie guatellisteinberg presents the long history of the human lineage from the earliest hominins to modern humans through their teeth. the book is laced with her understanding of this extensive and often contested history and is informed by her own work throughout. the book is divided into two sections based on broad temporal or genera distinctions, that is, early versus late hominins, or australopithecines (and paranthropus) versus homo species. within these major divisions each of the ten chapters addresses the defining characteristics and primary information that teeth have informed us about fossil species, crafting the larger story of the interpretations about the evolution of hominins. chapter 1 builds the background about what teeth can tell us from fossil specimens and introduces the broad sweep of our evolutionary history. this is followed by a focus on the australopiths and paranthropines, how they lived, and what they ate. chapter 3 pays special attention to the issue of canines, and what they mean in these early species with regard to diet, jaw architecture, and sexual selection. chapter 4 closes out the first part of the book by delving into how we know that juvenile growth periods were much faster among early hominins than among modern humans. the second part of the book opens with a similar introduction and outline for the evolution of the genus homo. chapter 6 focuses on the interrelationships between tooth size, diet, and the beginning of an evolution of culture across early homo species. chapter 7 again returns to issues of development as among the australopithecines, but also introduces longevity for early homo. chapters 8 and 9 focus on the diversity of information gained from studying neanderthal and modern homo sapiens teeth respectively. these chapters address issues like origins and phylogeny, diet and dental disease, and adaptations and life history. the final chapter serves to summarize the book’s main points and bring dr. guatelli-steinberg’s appreciation for, and perspective on, our dental evolution to the present, and into the future for dental paleoanthropology. the book is designed for undergraduates and non-professionals, but i think that it provides sufficient detail across the breadth of hominin dental studies that it would also offer a good reference piece for professionals and academics that focus on related research topics. “what teeth reveal about human evolution” is ambitious in its consideration of a significant diachronic perspective (~7 my), the ability to introduce and integrate the variety of perspectives that paleo-dental studies can provide, and the capacity to translate and collate that information for an audience generally lacking specialized knowledge. this book would work well in undergraduate courses on human evolution and as a supplementary companion to graduate seminars in related topics. james t. watson, ph.d. arizona state museum the university of arizona book review what teeth reveal about human evolution. debbie guatelli-steinberg. published in cambridge by cambridge university press , 2016. pp. 287. illus. indexed. isbn 978—1-118-84543-1, price: us$54.99 (paperback) ;isbn 978-1-107-44260-3 . da_07_02_powell and powell 1992.2 pg4.jpg pg5.jpg pg6.jpg wu and xianglong 1995.1 pg1.jpg pg2.jpg pg3.jpg pg4.jpg pg5.jpg morris 1993.7 pg14.jpg pg15.jpg pg16.jpg turner and eder 2006.2 15 most of human prehistory saw our ancestors living in small groups as opportunistic hunters and gatherers. studies of pre-agricultural teeth have repeatedly shown that diet and tooth use behaviors were abrasive, tough, and destructive, producing much tooth wear, periodontal disease, alveolar abscessing, and tooth chipping and fracturing. on the other hand, hunter-gatherers were largely free of both occlusal and interproximal caries and other disorders linked to cariogenic diets. despite archaeologically-derived preand early agricultural human teeth having been described many times around the world, there are very few accounts in the dental anthropological literature that include ethnographic observations of actual diet and tooth-use behaviors coupled with descriptions of the related oral pathologies and wear. this is especially so for remnant living groups whose consumption of refined sugar and flour is limited. the best known of such ethno-dentally described populations with minimal modern contact and exchange are the australian aborigines studied by t. d. campbell (1925, 1939) and the east greenland eskimo researched by p. o. pedersen (1938) . both workers were trained as dentists, which explains their interest in diet, toothuse, and oral pathology. ethnologists, on the other hand, almost always describe diet and food preparation techniques, but seldom comment on the resultant oral conditions. bioarchaeologists with paleo-ethnographic and dental interests describe oral health but generally lack the means to do more than infer diet based on archaeologically-recovered foodstuffs and artifacts dental pathology, wear, and diet in a hunting and gathering forest-dwelling group: the batak people of palawan island, the philippines christy g. turner ii* and james f. eder school of human evolution and social change, arizona state university, tempe, az abstract described are observations on batak foods, tooth use, oral hygiene, and resulting wear and oral pathology in dental casts of 29 batak ranging from 15 to 49 years of age. commonly consumed foods are roughly 80 percent plant, and 20 percent animal products. cooking is common. eating includes one or two main daily meals with occasional snacking. cariogenic commerciallymanufactured flour and sugar are rarely available. oral hygiene involves “finger-brushing” of anterior teeth with fine sand. the practice is more common in females than in males. caries are rare in both sexes as is antemortem tooth loss. tooth chipping is more common in males. periodontal disease is generally slight and nearly equal in the sexes. tooth wear is relatively slight but strongly age-related as in many other populations. dental anthropology 2006;19(1):15-22. involved in food-preparation. such artifacts include grinding stones, cooking vessels, butchered bones, and similar materials. rarely, human coprolites are recovered in archaeological excavations. these metabolic residues are inherently rich in dietary information. while the strength of bioarchaeological inference about diet and tooth-use behavior can be quite substantial, it is always desirable to have actual observations when dealing with uniformitarian cause and effect relationships, which in this case are diet, tooth use, and oral health. hence, this brief report identifies some of the foods and toothuse behaviors of the batak observed by ethnologist and co-author jfe, and the resultant effects on the dentition identified by bioarchaeologist cgt. information concerning the origin and affinity of the batak based on the dental morphology of the sample described herein can be found in turner and eder (2005). we hope this note will stimulate further dental anthropological study in the few remaining hunter-gatherer groups around the world. the batak are one of approximately twenty ethnolinguistically-distinct groups of so-called “negrito” peoples inhabiting various hinterland regions of the philippines. like other filipinos, they today speak languages of the austronesian language family, *correspondence to: christy g. turner ii. school of human evolution and social change, arizona state university, tempe, az 85287-2404 e-mail: chrstygturner@aol.com 16 and they share many cultural beliefs and practices with neighboring farming peoples. but philippine negritos stand out by virtue of their mobile forest foraging life way and the bundle of physical attributes—short stature, dark skin, and curly hair—that earned these distinctive-looking peoples their name (eder, 1987). the batak themselves inhabit a series of eight river valleys lying along the east coast of the north central part of palawan island, in the southwestern corner of the philippine archipelago. their subsistence economy today combines hunting and gathering, collection and sale of commercially valuable forest products, shifting cultivation, and wage labor for outsiders. wild yams and wild honey once provided the bulk of the carbohydrates in the batak diet. today, rice, corn, sweet potato, cassava, and plantain are also important starch sources. some brown sugar is used, but in small quantities and almost exclusively to sweeten coffee. protein sources include wild pig, gliding squirrels, porcupines, wild chickens, and other forest animals, and fish, eels, mollusks and crustaceans obtained from rivers and streams. bamboo shoots, rattan pith, and a variety of wild nuts, fruits, and greens are also consumed (eder, 1987). most food is roasted in wood fires or cooked (typically by boiling) in cast iron cooking vessels. typically there are two meals a day, one at noon and one in the evening, but sometimes there is only one. there is often considerable snacking in the course of the day, as foods are encountered on the trail or brought into camp. the contemporary diet is low in animal protein, low in vegetables, and probably even low in calories. actual food consumption patterns can be narrow and monotonous for extended periods of time. drinking water is obtained from springs and streams. teeth are cleaned with toothpicks and finger-brushed with fine sand or (sometimes) with toothbrushes. betel nut chewing is common, and all adult teeth are stained accordingly. materials and methods eder and helpers collected dental impressions of 29 batak natives whose ages ranged from 15 to about 49 years. the sample size was limited by the amount of impression powder (jeltrate®) and plaster that could be conveniently carried into the field along with other more critical supplies. positive plaster casts were poured immediately after the impressions were made. 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 14 16 f f f 18 m f 20 f f 22 f f f 24 f 26 m m 28 m f m m �0 f f m �2 34 �6 m �8 40 42 44 46 m m f m 48 50 f fig. 1. distribution between the average wear (horizontal axis) and the person’s age (vertical axis) for maxillary teeth. average wear was based on the 5-grade ordinal scheme: 0 = no wear, 1 = dentine exposed, 2 = cusps worn off, 3 = pulp exposed, 4 = root stump functional (turner, nichol and scott, 1991). the correlation coefficient between age and mean wear for batak male maxillary teeth is r = 0.749; for batak females, r = 0.894. sex of the specimen is coded as male (m) or females (f). c.g. turner ii and j.f. eder 1� descriptions of the dental conditions are based on standards used in the arizona state university dental anthropology system (asu das) (turner, nichol and scott, 1991). results wear tooth wear was scored for all observable occlusal surfaces. the mean scores for each of the studied batak males and females is given in tables 1 and 2. as is evident, tooth wear is strongly related to age, i.e. mean wear, which was calculated by summing the wear scores for each tooth in an individual and dividing by the number of teeth that the individual possessed. for example, male number 3 in table 1, age 19, had a total maxillary wear score of 9.0, which divided by his 16 teeth gives a mean wear score of 0.56. in contrast, the 47 year old male number 7 has a mean maxillary wear score of 1.10. this is almost exactly twice that of batak number 3. the relationship between age and mean wear is plotted in figures 1 and 2. the age-mean wear relationship is quite evident, that is, strongly positive. the correlation coefficients for upper male age-mean dental wear is r = 0.749; for female upper teeth r = 0.894. for the lower jaws, male r = 0.860; female r = 0.866. these values suggest that the tooth wear scores provided here could serve as a useful guide for estimating age in prehistoric hunter-gatherers who lived in habitats similar to that of the batak. a relationship between tooth wear and caries in these hunter-gatherers can also be seen. in tables 1 and 2, some of the males and females with one or more carious teeth have mean wear scores somewhat less than non-carious individuals of comparable age. one interpretation of this relationship is that individuals with caries do not chew as much or as heavily as do caries-free individuals. obviously, the relationship between caries and tooth wear would have some effect on how much one can rely on wear to aid in estimating age of prehistoric human remains. although interproximal caries could not be looked for in our dental casts, we assume that there were some, and that they also contributed to lowered use of the jaws due to pain and discomfort. 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 14 16 f f f 18 f 20 m f 22 f f 24 f f f 26 m f 28 m f m �0 m m �2 f f m 34 �6 m �8 40 42 44 46 f m 48 m m 50 f fig. 2. distribution between the average wear (horizontal axis) and the person’s age (vertical axis) for mandibular teeth. average wear was based on the 5-grade ordinal scheme: 0 = no wear, 1 = dentine exposed, 2 = cusps worn off, 3 = pulp exposed, 4 = root stump functional (turner, nichol and scott, 1991). the correlation between age and mean wear for batak male maxillary teeth was r = 0.749; for batak females, r = 0.894. sex of the specimen is coded as male (m) or female (f). batak of palawan island 18 table 1. batak maxillary dental wear individual total number mean number age wear of teeth wear caries male maxilla 3 19 9.0 16 0.56 27 26 12.0 16 0.75 1 28 13.0 16 0.81 21 28 14.0 16 0.87 20 29 12.0 16 0.75 rm1 23 29 17.0 16 1.06 11 31 22.0 16 1.37 10 36 21.5 15 1.43 5 45 26.5 13 2.04 22 >45 31.5 14 2.25 7 47 16.5 15 1.10 lp1 1�a adult 15.5 12 1.29 female maxilla 2 15 8.0 16 0.50 9 15 10.5 14 0.75 rm1 26 15 8.0 14 0.57 28 18 7.0 14 0.50 8 20 10.0 16 0.62 rm1 4 21 11.0 16 0.69 25 22 9.0 16 0.56 24 22 11.5 15 0.77 14 23 13.0 14 0.93 17 23 12.0 16 0.75 lm3 18 24 12.5 16 0.78 12 26 15.0 16 0.94 16 ~ 28 13.0 16 0.81 29 30 19.5 16 1.22 19 30 12.5 16 0.78 6 46 23.0 16 1.44 15 ~ 49 36.0 15 2.40 lrm1 aman had congenital absence of four upper teeth (lri2, rc, lm3) and three lower teeth (ri1, lrm3). see figs. 7 and 8. table 3 provides the frequencies of crown caries, antemortem tooth loss, crown chipping, periodontal disease, and oral hygiene. inasmuch as these observations were made from plaster casts, the values probably err slightly on the side of under-reporting; for example, caries and toothpick grooves could not be looked for on interproximal crown surfaces including those of the roots. the extent of general bone loss from periodontal disease, which is easily studied in skeletal remains, is largely hidden by gum tissue in the living. caries the number of batak with one or more crown caries (31.0%) is unexceptional for a hunting and gathering population, although it is at the upper end of the range. among the middle to late period (ca. 1,000 b.c.) jomonese of central japan (a hunting, fishing, gathering, and possibly small scale horticultural population), the percentage of individuals with one or more caries was 42.7% (turner, 1979). the frequency of batak carious teeth (2.1%), mostly molars, is well in line with prehistoric hunting and gathering economies around the world. within the batak sample, there is no statistically significant difference between males and females for caries. antemortem loss the low amount of antemortem tooth loss is consistent with the low frequency of caries—caries being viewed as the major cause of antemortem loss, c.g. turner ii and j.f. eder 19 fig. 4. labial surface smoothing of cast number 7 upper central incisors, an adult batak male, age about 47 years. periodontal disease was judged to be “medium” (cgt neg. 3-22-02:24). fig. 3. labial surface smoothing of upper left and right central and lateral incisors. the cast (number 3) was from a young batak adult male, age 19 years (cgt neg. 3-22-02:27). fig. 5. arrows point to occlusal chipping of cast number 21, an adult batak male, age 28 years (cgt neg. 3-22-02:20). fig. 6. periodontal disease of cast number 14, an adult batak female, age 23 years. disease grade judged to be “slight” (cgt neg. 3-22-02:22). especially for molars, which is the situation in this sample. two lost incisors occurred in males. trauma likely was the cause of the loss. combining antemortem loss and carious teeth, only 3.0% of all teeth have one or both of these conditions. this is far less than what occurs in agricultural populations with their highly processed, sticky, and cariogenic cereal-based foodstuffs. chipping occlusal surfaces of an individual’s teeth may exhibit one or more nicked or chipped edges. chipped areas are usually less than 0.5 mm in diameter (figs. 5 and 8). chipping is attributable to various activities ranging from the heavy use of teeth as vice-like tools, breaking up of hard materials like starvation-driven scavenging of bone, gritty mineral food contaminants, to accidental trauma arising from falls, and other sources. both individual and tooth counts show that the batak males have significantly more chipping than do the females. almost all males have one or more chipped teeth (91.7%) in contrast to females (35.3%) who have only about one third of their number exhibiting chipping. pooled, the number of chipped teeth occur more often in the back of mouth (chipped incisors, 9; canines, 3; premolars, 21, molars, 26), suggesting dietary and tooth use activities as the major contributor to batak chipping rather than trauma. eder notes that chipping was not likely caused by fighting since males never fight among themselves. there is nothing in these values to suggest excessive inter-sex conflict where one would expect either comparable overall female tooth chipping (females being abused and hit; male chipping due to heavy tooth use), or excessive anterior tooth chipping (falls by children, adolescent hitting, being shoved, etc.). eder feels that the observed pattern batak of palawan island 20 table 2. batak mandibular dental wear individual total number mean number age wear of teeth wear caries male maxilla 3 19 9.0 16 0.56 27 26 11.0 16 0.69 1 28 12.0 16 0.75 21 28 14.0 16 0.87 20 29 10.5 16 0.66 23 29 17.0 16 1.06 11 31 18.0 16 1.12 10 36 17.5 16 1.09 lrm2, m3 5 45 25.0 12 2.08 22 > 45 27.0 16 1.69 rm2 7 47 19.5 16 1.22 13 adult 20.0 13 1.54 female maxilla 2 15 8.0 16 0.50 9 15 8.0 14 0.57 lm1 26 15 9.5 14 0.68 28 18 10.0 14 0.71 8 20 12.5 16 0.78 4 21 12.0 16 0.75 25 22 11.5 15 0.77 24 22 12.5 16 0.78 14 23 11.0 14 0.79 17 23 14.5 16 0.91 18 24 12.5 16 0.78 12 26 15.0 16 0.94 16 ~ 28 13.5 15 0.90 rm1,2; lrm3 29 30 15.5 16 0.97 19 30 12.0 16 0.75 6 46 24.0 16 1.50 15 ~ 49 14.0 13 1.08 lm2 almost certainly relates to a disproportionate tendency for men more than women to put non-food items in their mouths in the course of producing artifacts, or ad hoc tools. despite the sexes basically eating the same foods, he has seen batak men more often than women biting on lengths of rattan, and using their teeth to crack open nuts, break bones to obtain the marrow, and even chewing on turtle carapaces. after such sorts of tooth use to access nutrients, the man would share with his wife or others. periodontal disease while nearly all of the 29 batak exhibit some degree of gingival border recession, detachment, and swelling, indicating bacterial infection and inflammation, we characterize the amount as having been mostly slight in both sexes (fig. 6). there is, as expected, a small degree of age-related expression of periodontal disease, but the relationship is weak. periodontal disease among the batak sample seems more idiosyncratic than systematic. thus, the batak oral activities, while culturally and environmentally channeled, have also a degree of individual determination. this can include regularity of oral hygiene practiced, immune strength, amount of fibrous and other foods consumed that have the inherent capability to remove plaque, and other such variables, including choices of foods that might possess antibacterial or anti-inflammatory qualities. oral hygiene the type of oral hygiene that can be detected from our batak dental casts includes an interesting flattening of the labial surface of one or more upper incisors and canines (figs. 3 and 4). as eder observed, c.g. turner ii and j.f. eder 21 table 3. batak oral health male female m & f χ2 total condition n percent n percent p-value n percent individuals, 1 or more caries 4 33.3 5 29.4 n.s. (> 0.80) 9 31.0 individuals, no caries 8 66.7 12 70.6 20 69.0 carious incisors, n = 227 0 0 0 carious canines, n = 115 0 0 0 carious premolars n = 232 1 0 1 carious molars n = 315 6 11 17 carious teeth n = 889 7 11 n.s. (> 0.80) 18 2.1 antemortem loss, incisors 2 0 2 antemortem loss, canines 0 0 0 antemortem loss, premolars 0 0 0 antemortem loss, molars 3 4 7 caries & antemortem loss, n = 898 12 3.3 15 2.9 27 3.0 individuals, chipping, n = 29 11 91.7 6 35.3 sig. (< 0.01) 17 58.6 teeth, chipping, n = 887 37 10.1 14 2.7 sig. (< 0.01) 51 5.7 (male = 366; female =521) periodontal disease, individuals absent 0 0.0 4 25.0 4 13.8 slight 8 66.7 10 62.5 18 62.1 medium 3 25.0 1 6.2 4 13.8 severe 1 8.3 1 8.3 2 6.9 total 28 96.5 upper labial flattening, inds. 6 54.5 15 88.2 sig. (< 0.01) 21 75.0 lower labial flattening, inds. 0 0.0 0 0.0 0 0.0 central incisors, flattened 10 50.0 34 88.2 sig. (< 0.01) 54 81.5 lateral incisors, flattened 6 30.0 20 58.8 sig. (< 0.05) 54 48.1 canines, flattened 3 14.3 14 41.2 sig. (< 0.05) 55 30.9 developmental disturbance that might have had a link to fixed or unfixed external environmental factors, even possibly involving the degree of group inbreeding or population genetic bottle-necking sometime in the past. in any event, congenital absence is a category of dental variation that often gets left out of both morphological and pathological characterizations of human populations. discussion as hunting and gathering disappears as an economic way of human life, the opportunity to observe the ethnography of dentally related activities and diet, and to match these observations with the resultant effects on teeth, is drawing to a close. in fact, very few ethnographic observations on tooth use and this labial flattening results from the abrasive action of finger-brushing using fine sand or silt in water. there are significantly more females (88.2%) with labial-abrasion than males (54.5%). this holds also for the actual number of abraded teeth (table 3). the absence of abraded lower anterior teeth is interesting from a cosmetic standpoint, as it is primarily the upper anterior teeth that are apparent during smiling or other teeth-displaying behavior. congenital absence figures 7 and 8 show upper and lower dental casts of a batak male who likely had seven congenitally missing teeth. while congenital absence is not normally considered as an oral pathology, we nevertheless include the illustrations to indicate some manner of batak of palawan island 22 fig. 8. absence of three mandibular teeth of cast number 13 (fig. 7). missing are the right central incisor, and both third molars. cusp 2 of the right second molar is chipped (cgt neg. 3-22-02:17). fig. 7. absence of four maxillary teeth of cast number 13, a batak male, age about 34 years. presumably congenitally missing are the right lateral incisor and canine, the left lateral incisor, and the left third molar. the right third molar is peg-shaped with a lingualbuccal diameter of 6.5 mm. there is a cone-shaped supernumerary tooth between the central incisors (cgt neg. 3-22-02:15). diet, coupled with oral pathology examinations, can be found in the dental anthropological literature. those that are best known were made by dentists, seldom anthropologists. hence, this brief report represents a contribution to an uncommon line of investigation of human tooth use and its results. our sample comes from a remnant forest-dwelling hunting and gathering group living in the philippines, the batak. the results of our pathology examination (wear, caries, antemortem loss, chipping, periodontal disease, oral hygiene) of living batak people are nicely in line with other dental studies of prehistoric hunting and gathering people throughout the world. the dentally destructive diet associated with cariogenic agricultural foodstuffs and processing is not evident in the batak sample. what stands out as markedly different is the effect of oral hygiene on the batak upper anterior teeth, the observed actual activities demonstrably producing the labial flattening of the upper anterior teeth. this flattening would normally have been considered as intentional modification had the acts of teeth cleansing not been observed by the ethnographer (jfe). also, the probable cause of tooth chipping has been identified as a result of ethnographic observation. acknowledgments the dental impressions were collected with the assistance of rafaelita fernandez and raul fernandez, from the batak inhabiting the langogan river valley of central palawan island. literature cited campbell td. 1925. dentition and palate of the australian aboriginal. adelaide: university of adelaide publications, keith sheridan foundation no. 1. campbell td. 1939. food, food values and food habits of the australian aboriginals in relation to their dental conditions. aust j dent 43:1-15. eder jf. 1987. on the road to tribal extinction: depopulation, deculturation, and adaptive wellbeing among the batak of the philippines. berkeley: university of california press. pedersen po. 1938. investigations into dental conditions of about 3,000 ancient and modern greenlanders. dental record 58:191-198. turner cg ii, eder jf. 2005. dentition of the batak people of palawan island, the philippines: southeast asian negrito origins. in: oxenham m, tayles n, editors. bioarchaeology of southeast asia. cambridge: university of cambridge press, p 172-187. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley liss, p 13-31. c.g. turner ii and j.f. eder zubov 1992a.2 pg4.jpg pg5.jpg pg6.jpg pg7.jpg pg8.jpg k turner 1995.5 pg14.jpg swails 1995.1 pg3.jpg pg4.jpg pg5.jpg pg6.jpg pg7.jpg adegboye 1988.1 pg4.jpg pg5.jpg merbs 1994.3 pg10.jpg pg11.jpg dahlberg 1993.1 pg2.jpg pg3.jpg drusini and swindler 1994.3 pg11.jpg 89 dental anthropology 2019 │ volume 32 │ issue 02 this special edition of dental anthropology is based on a symposium from the 2018 american association of physical anthropologists annual meeting entitled, reevaluating the meaning of ‘oral health’ in bioarchaeology that i co-chaired with james p. fancher. the goal of this symposium was to begin a dialogue on how oral health is defined and evaluated in a bioarchaeological context. invited participants explored definitions and interpretations of this term within their own work. out of the initial discussion at this symposium, presentations were turned into the manuscripts presented here. the volume begins with an outline of various conditions that are traditionally used in studies of oral health. the articles that follow explore traditional markers of oral health, predominately focused on periodontal disease and dental caries. interpretations are then nuanced within a biocultural context using the archaeological record and what is known abut the etiology and progression of these conditions. the resulting volume is a thoughtful evaluation of how oral health can be studied in bioarchaeology. the hope is that discussions will continue and further questions will be raised about bioarchaeological research and its limitations. with particular attention to terminology, the limits of diagnoses, the integration of clinical literature, and the development of advanced methods of study. thanks to the many authors who contributed to this volume and those who contributed to the initial symposium. their work, discussions, and contributions to this journal are appreciated and will serve to grow the study of pathological conditions of the oral cavity and contribute to a better understanding of oral heath in the past. marin a. pilloud editor of dental anthropology department of anthropology university of nevada, reno reno, nv 89557 editor’s note on special edition on oral health cooke 1993.6 pg10.jpg hillson 1992.5 pg12.jpg irish 1993.4 pg18.jpg pg19.jpg s1. cohen’s kappa agreement coefficient. agreement according to (landis & koch, 1977). variable grade threshold n kappa agreement shoveling ui1 3 109 0.89 almost perfect agreement double shoveling ui1 2 109 0.92 almost perfect agreement interruption groove ui2 1 102 0.70 substantial agreement tuberculum dentale ui2 2 102 0.62 substantial agreement bushman uc 1 123 0.83 almost perfect agreement accessory cusps up1 1 124 0.69 substantial agreement accessory ridges up2 2 116 0.68 substantial agreement metaconule um1 1 142 0.53 moderate agreement carabelli cusp um1 3 142 0.61 substantial agreement hypocone um2 3 127 0.64 substantial agreement parastyle um3 2 81 0.63 substantial agreement lingual cusp number lp2 2 129 0.65 substantial agreement deflecting wrinkle lm1 2 147 0.69 substantial agreement anterior fovea lm1 2 147 0.54 moderate agreement protostylid lm1 2 147 0.56 moderate agreement entoconulid lm1 1 147 0.73 substantial agreement metaconulid lm1 1 147 0.63 substantial agreement groove pattern lm2 y 129 0.78 substantial agreement hypoconulid lm2 1 129 0.74 substantial agreement odontome up/lp 1 500 0.77 substantial agreement landis, j., & koch, g. (1977). the measurement of observer agreement for categorical data. biometrics. s2.1. spearman correlation test using data set a) only wear-biased traits. s2.2. spearman correlation test using data set b) only unbiased traits. s2.3. spearman correlation using data set c) with biased and unbiased traits kashibadze 1991.2 pg6.jpg pg7.jpg garn 1992.1 pg2.jpg muller 2006.4 62 verwandschaftsanalyse im alemannischen gräberfeld von kirchheim/ries (analysis of relationships within the alemannic linear graveyard of kirchheim/ries [in german]) by kurt w. alt and werner vach. basler hefte zur archäologie volume 3 2004. archäologieverlag basel. archaeologists have long been stymied when confronting a fundamental aspect of ancient social systems—kinship. while kinship terms and systems are featured in every beginning cultural anthropology textbook, archaeologists were left wondering if their ceramic design motifs or the spatial patterning in cemeteries really provided insight into relations of marriage and descent in ancient societies. in response to this need, alt and vach set out to develop a method of assessing genetic relationships among individuals in skeletal samples derived from archaeological contexts. the method has been used on skeletal material collected from a large variety of archaeological contexts of varying sample sizes, such as a mass grave from the roman imperial period, neolithic mass graves in germany and abu dhabi, a paleolithic triple burial, an early iron age cemetery, a late slavic cemetery, and a merovingian cemetery, several reports of which have also been published in english (alt et al., 1995a; alt et al., 1995b; alt et al., 1997; alt and sedlmeier, 1990; alt and vach, 2001; alt et al., 1995c; alt et al., 1992). this monograph concerns the skeletal sample at the alemannic cemetery of kirchheim/reis, which represents the largest sample yet investigated using their methods. the body of the monograph is written in german, although summaries in french, italian and english present basic information about the cemetery, the methodology, and the results. the authors begin chapter 1 with a consideration of the goals of a biological kinship analysis and how it can serve to further the traditional archaeological goal of understanding ancient social systems. they include a critical consideration of how the terminology and concepts employed in biological kinship analysis intersect with established (although sometimes contentious) concepts within socio-cultural anthropology and archaeology. the authors make it clear that socially defined kinship relations do not necessarily have biological components and therefore cannot be investigated using techniques that rely on genetic relationships among individuals. the authors realize that the results of their analyses provide only part of the picture and that additional sources of archaeological and anthropological data must be consulted. in chapter 2, the authors present the methodological foundation of their approach for investigating biological kinship among ancient populations. dr. alt, a physical anthropologist, and dr. vach, a statistician, have developed a statistical method to assess biological kinship based on the comparison of similarities among individuals using a large catalog of non-metric traits of the skull, jaws, and teeth (alt, 1997). certain assumptions and potential issues must be considered when using this approach. for example, the method relies on a comparison of phenotypic similarities. in other words, it relies on the portion of any shared genetic information that is actually expressed as traits in common among individuals, and therefore does not directly identify the specific genetic relationship between individuals. in addition, the analysis is based on the observation of non-metric traits with varying penetrance and expressivity. this means that family members can only be identified in the event that they express traits typical of their family and that such traits are observable. in many cases, traits are obliterated by dental wear and disease as well as taphonomic processes. for a large, relatively well-preserved sample such as kirchheim/ries, these problems are minimized. in order to find related individuals, the method employs a statistical search procedure that compares each individual and each trait to create combinations of individuals (termed “structures”). significant structures are based on non-metric traits with low frequencies in the population, which also have a low global probability of conspicuousness (g-value), indicating a low probability of observing the same combination by chance among unrelated individuals in the sample. more detailed discussions of the method and its statistical basis have been published in english (alt and vach, 1991; alt and vach, 1992; alt and vach, 1993; alt and vach, 1998). in chapters 3 and 4, alt and vach present the results of their analyses of the cemetery at kirchheim/ries. in total, 460 individuals were scored for 933 non-metric traits of the skull, jaws, and teeth. since the sample of individuals from the total cemetery was quite large, the authors were able to investigate subgroups within the cemetery and still maintain reasonable sample sizes. this procedure ensured that the analysis was not dominated by large, very robust groups or individuals with a large number of well-preserved, rare traits. they looked for both general patterns based solely on the non-metric traits, and on subgroups created using archaeological attributes such as chronological time period, sex of the individual, spatial organization, wealth of grave goods, and types of grave goods. results of the analysis of all graves revealed eight familial structures, some of which have additional archaeological characteristics that indicate a social relationship as well. an unexpected result from the analysis of all graves is the relatively large number of individuals who appear in more than one of the eight book review 63 groups, which suggests genetic interrelationships among the eight possible families that used the cemetery. archaeological mortuary analyses rely upon spatial patterning in cemeteries, grave construction, and assemblages of grave goods to recreate a sense of the social identity of an individual. comparison of these data for all the individuals in a cemetery facilitates the reconstruction of the social organization as expressed in burial practice. however, there has been debate as to which aspects of burials reflect which aspects of social organization, for example vertical social status (wealth), horizontal social status (one’s position in relation to others within the same level of a hierarchy), or membership in other types of groups such as kin groups, trades, or religious groups. in their analysis of the cemetery at kirchheim/ries, alt and vach demonstrate that, for some types of grave goods, it is possible to identify biological kin structures that are at least partly correlated with certain types of grave goods. in a previous cemetery analysis, jorgensen (jorgensen et al., 1997) identified 14 likely familial groupings of graves based on archaeological mortuary data. tests seeking a biological basis for the 14 archaeologically defined familial groupings revealed only one convincing biological family structure (group iv), although sample sizes for some of the hypothesized archaeological family groups were small due to poor preservation. analysis of subgroups defined by the presence of specific grave goods met with more success. several new familial structures were identified, and these frequently showed spatial clustering as well. in many cases, the structures contained several graves with a particular item, but also some graves without it. additionally, the same items also occurred in graves that were not in the structure. this phenomenon illustrates the difficulties of identifying familial structures based on archaeological evidence alone, as well as the utility of testing archaeological subgroups in biological kinship analysis. perhaps the most powerful results for the understanding of the social organization at the cemetery of kirchheim/ries come from the analysis of the “traditional aristocracy” (those showing unusual wealth) within the main cemetery and the analysis of the spatially distinct “noble burial compound”, which contained wealthy burials dating only to the final three chronological phases of the cemetery. previous archaeological interpretations had speculated that the nobles were locals originally interred as part of the general population, who later founded their own distinct cemetery to emphasize their separate identity. analysis of the “traditional aristocracy” within the main cemetery shows biological kinship structures among its members, as well as possible connections to other burials within the main cemetery. analysis of the spatially distinct noble burial compound revealed fundamental differences between its population and the main cemetery that can only be explained by the presence of two genetically distinct populations. archaeologically, individuals interred in the noble burial compound show affinities to the avars (an eastern tribe contemporaneous with the alemanni) in both material culture and burial rituals. a contentious area of archaeological research lies in understanding the process of the introduction of new material culture and cultural practices. it is often unclear whether the appearance of new elements indicates the movement of actual people or the diffusion of goods and ideas, especially in times of intensive population movement. although the geographic origin of the individuals within the noble burial compound cannot be identified based on their skeletal traits, the biological kinship analysis did reveal that the appearance of foreign material culture and burial practices at the cemetery of kirchheim/ries coincided with the arrival of a genetically distinct population. alt and vach’s analysis of the alemannic cemetery at kirchheim/ries provides an excellent example of the effective use of non-invasive, non-destructive methods for analyzing dental and skeletal data in a truly bioarchaeological context. the results of their analyses demonstrate the potential for biological kinship analysis to add a new dimension to mortuary analysis and a new source of data that can be applied to some of archaeology’s most perplexing problems. deann muller department of anthropology the university of chicago literature cited alt k. 1997. odontologische verwandtschaftsanalyse. stuttgart: gustav fischer. alt k, munz m, vach w. 1995a. hallstattzeitliche grabhügel im spiegel ihrer biologischen und sozialen strukturen am beispiel des hügelgräberfeldes von dattingen, kr. breisgau-hochschwarzwald. germania 73:281-316. alt k, pichler s, vach w. 1995b. familial relationships of inhabitants of a late-roman villa rustica. in: jacob b, bonte w, alt k, pieper p, editors. advances in forensic sciences. berlin: köster, p 263-267. alt k, pichler s, vach w, klima b, vlcek e, sedlmeier j. 1997. twenty-five thousand-year-old triple burial from dolni vestonice—an ice age family? am j phys anthropol 102:123-131. alt k, sedlmeier j. 1990. anthropologishce untersuchung und kulturhistorische bedeutung des menschlichen zahnfundes aus der kohlerhöhle, gemeinde brislach, kanton bern. archäologisches korrespondenzblatt 20:241-248. alt k, vach w. 1991. the reconstruction of genetic kinship book review 64 in prehistoric burial complexes-problems and statistics. in: bock h, ihm p, editors. classification, data analysis, and knowledge organization. new york: springer, p 299-310. alt k, vach w. 1992. non-spatial analysis of “genetic kinship” in skeletal remains. in: schader m, editor. analyzing and modeling data and knowledge. berlin: springer verlag. alt k, vach w. 1993. detection of kinship structures in prehistoric burial sites based on odontological traits. in: andresen j, madsen t, scollar i, editors. computing the past: computer applications and quantitative methods in archaeology: aarhus: aarhus unversity press. alt k, vach w. 1998. kinship studies in skeletal remains: concepts and examples. in: alt k, rösing f, teschler-nichola m, editors. dental anthropology: fundamentals, limits, and prospects. new york: springer, p 537-554. alt k, vach w. 2001. untersuchungen zur verwandtschaftsstruktur der merowingerzeitlichen bevölkerung von eichstetten am kaiserstuhl. in: sasse b, editor. ein frühmittelalterliches reihengräberfeld bei eichstetten am kaiserstuhl. stuttgart: konrad theiss verlag, p 475-642. alt k, vach w, frifelt k, kunter m. 1995. familienanalyse in kupferzeitlichen kollektivegräbern aus umm annar; abu dhabi. arab archaeological epigraphs 6:65-80. alt k, vach w, pichler s. 1992. familienanalyse an kaiserzeitlichen skelettresten aus einer villa rustica be regensburg-harting. bayerischer vorgeschichtsblatt 57:261-276. jorgensen l, alt k, vach w. 1997. families at kirchheim am ries. analysis of merovingian aristocratic and warrior families. in: a jorgensen a, clausen b, editors. military aspects of scandinavian society in a european perspective, ad 1-1300. copenhagen, p 103-112. book review harris 1993.5 pg12.jpg haeussler 1993.8 pg17.jpg sciulli 2002.1 33 abstract. dental asymmetry (directional, antisymmetry, and fluctuating) is analyzed in samples from two prehistoric native american populations: a terminal late archaic population (3200-2700 bp) and a late prehistoric population (ca. 750 bp). both directional and fluctuating asymmetry were found in each sample. directional asymmetry occurs in only four teeth in the late archaic sample and in two teeth in the late prehistoric sample. neither sample exhibits the tendency for opposing arch dominance in directional asymmetry. fluctuating asymmetry is significantly greater than measurement error for all teeth in each sample. however, contrary to expectations the late prehistoric maize agriculturists do not show an overall greater degree of fluctuating asymmetry compared developmental stability is the result of processes that act to insure that features of organisms differentiate, grow, and mature along their genetically predetermined pathways (waddington, 1957). two primary hypotheses have been offered to explain the genetic basis of developmental stability: the heterozygosity and the genomic coadaptation hypotheses. the heterozygosity hypothesis proposes that developmental stability is augmented by increasing heterozygosity. the mechanism for increased stability with increased heterozygosity may be greater biochemical efficiency (mitton, 1994) or an increase in the range over which metabolic functions can be performed (watt, 1983). the genomic coadaptation hypothesis proposes that developmental stability results from the action of natural selection which establishes and maintains complex genetic interactions, a genetic balance, over the evolutionary history of taxa (dobzhansky, 1970; mather, 1973). recently it has been shown that heat-shock protein 90 (hsp90), an essential and abundant protein at normal temperatures and induced by stress in all eukaryotes tested,buffers developmental stability against stochastic processes (queitsch et al., 2002). hsp90 normally acts to reduce the likelihood that stochastic events will alter the deterministic path of developmental programs by chaperoning metastable proteins and stabilizing them in conformations that allows them to be activated in the proper time and place (queitsch et al., 2002). hybridization, according to the heterozygosity hypothesis, is expected to increase developmental stability while the genomic coadaptation hypothesis would predict reduced stability from hybridization. in some cases of hybridization between subspecies increased developmental stability for some features has been found (ailbert et al., 1997; freeman et al., 1995). generally however developmental stability appears to decrease when coadapted gene complexes are disrupted (graham, 1992) with the effect on developmental stability modified by the degree of divergence between the hybridizing taxa and the recency of hybridization (markow and ricker, 1991). hsp90 may also be affected by increased polymorphism. while hsp90 buffers the expression of genetic variation, extensive polymorphism in genomes may exceed hsp90’s ability to maintain functional developmental pathways resulting in reduced stability or altered features (queitsch et al., 2002). in addition to genetic causes environmental factors may affect developmental stability (waddington, 1960; siegel and doyle, 1975a; 1975b; 1975c; hurtado et al., 1997). environmental stress is hypothesized to reduce developmental stability by decreasing the ability of organisms to buffer against developmental noise or by increasing developmental noise by increasing intracellular stress (hochwender and fritz, 1999; queitsch et al., 2002). reduced developmental stability can be measured by the analysis of fluctuating asymmetry (parsons, 1990; clarke, 1992; graham et al., 1993; woods et al., 1998; nosil and reimchen, 2001). fluctuating asymmetry (fa), the variance in random deviations from exact bilateral symmetry, is considered a dental asymmetry in a late archaic and late prehistoric skeletal sample of the ohio valley area paul w. sciulli* department of anthropology, the ohio state university, columbus, ohio 43210 *correspondence to: paul w. sciulli, department of anthropology, the ohio state university, columbus, ohio 43210. e-mail: sciulli.1@osu.edu to their forager ancestors. this result coupled with a survey of pathological conditions in these populations suggest that stress levels in ohio valley populations, at least that stress which affected dental developmental stability, were not drastically increased with the introduction of maize agriculture. spearman correlations between relative tooth size variation (coefficient of variation), the magnitude of fluctuating dental asymmetry, and duration of time (per tooth) spent in soft tissue development were obtained for each sample. coefficients of variation and fluctuating asymmetry are significantly correlated in both samples but fluctuating asymmetry is significantly correlated with duration of soft tissue development only in the late prehistoric population. 34 35p. s. sciulli measure of developmental stability because the sides of bilaterally symmetrical organisms share the same genotype and environmental differences between the sides, summed over development, are likely to be small. the differences between features from the sides of organisms can then be attributed primarily to random errors that accumulated in development (klingenberg and nijhout, 1999). a large accumulation of random errors in development will lead to greater magnitudes of fa and indicate reduced developmental stability. although there is substantial support for the hypothesis that increased environmental stress leads to increased fa (parsons, 1990) some studies have found no association between fa and increased stress (see palmer and strobleck, 1986). this situation occurs particularly for studies of environmental stress in natural (non-experimental) populations. this inconsistency may arise because natural environmental perturbations were not severe enough (compared to experimental manipulations of environment) to affect fa and because not all features respond to stress in the same manner. response to a given type of stress may be feature specific and some features may not be reliable indicators of increased environmental stress (parsons, 1990; woods et al., 1998). while all features in organisms may not reflect increased stress by the analysis of fa, the human dentition does appear to be a reliable indicator if levels of stress are relatively high and sample sizes are adequate (parsons, 1990). variation in fa among both living and prehistoric human groups have provided indirect evidence of variation in developmental stability (bailit et al., 1970; doyle and johnston, 1977; perzigian, 1977; dibernanardo and bailit, 1978; townsend and brown, 1980; harris and nweeia, 1980; townsend, 1981; kieser et al., 1986; mizoguchi, 1986; kieser and groeneveld, 1988). the purpose of the present study is to compare levels of fluctuating dental asymmetry in samples of two prehistoric native american populations from the ohio valley region. the populations represent an evolving lineage (sciulli and oberly, 2002) with one population extant during the late archaic period (ca. 3200-2700 bp) and the second extant during the late prehistoric period (950-300 bp). the earlier late archaic population subsisted primarily as hunter-gatherers while the late prehistoric population practiced maize agriculture. the transition to agriculture is associated with an inferred decline in general health status for many prehistoric populations (cohen and armelagos, 1984; cook, 1984; cohen, 1989; larsen, 1995; steckel and rose, 2002). this inference is based on the general increase in prevalence of skeletal and dental lesions found in agricultural populations compared to their forager ancestors and is hypothesized to have resulted from an increase in physiological stress due to a reduction in the quality of the diet, an increased prevalence of infectious disease (due to crowding), and the synergistic effects of poor diet and diseases (goodman and armelagos, 1989; larsen, 1995). thus based on this hypothesis the late prehistoric maize agriculturalists are expected to show higher levels of fa compared to their late prehistoric forager ancestors. the amount of fa as well as relative size variation have been found to be associated with the duration of the pre-calcification stage of tooth development (mizoguchi, 1980; farmer and townsend, 1993; townsend and farmer, 1998). the present study will, in addition to the comparisons of fa, review the potential associations among these variables both within and between the samples.fig. 1. map of ohio showing locations of late archaic (boose, kirian, treglia, and duff) and the late prehistoric pearson village sites. 34 35 material and methods samples two samples are used in the present study: late archaic and late prehistoric. the late archaic sample is derived from a population that was distributed in northwestern ohio and composed of slightly differentiated subpopulations among which differentiation was related to the geographical dispersion of the subpopulations. the minimum fst, a measure of population divergence, for late archaic subpopulations is 0.039, similar in magnitude to fst values found for more recent eastern woodlands subpopulations (jantz and meadows, 1995; rangdon, 1995; tatarek and sciulli, 2000). habitation sites of the late archaic subpopulations have yet to be discovered and archaeological data relating to subsistence-settlement patterns are thus lacking. analysis of dental disease and stable carbon isotope ratios, however, have shown that late archaic subpopulations exhibited patterns of these diet indicators similar to hunting-gathering populations (sciulli, 1997). archaeological data from neighboring regions suggest that late archaic subpopulations subsisted by hunting-gathering with the probable inclusion of some native domesticated plants to the diet (smith, 1989; 1995). three late archaic subpopulations are used in this study to represent the late archaic population: boose (sciulli and schuck, 2001), kirian treglia (sciulli et al., 1993), and duff (sciulli and aument, 1987). these subpopulations are used because preservation was good, individuals were fairly complete, each sex was represented, and these were the largest subpopulations available. a total of 54 late archaic adults (18-35 years) comprise the sample with an equal number of males and females. the late prehistoric sample studied here is from the sandusky tradition, pearson village. a total of 86 adults, 43 males and females, are sampled from the middle cemetery (sciulli et al., 1996). the middle cemetery is associated with the north pearson village (ca. 750 bp) which was a late spring to early fall base camp at which maize agriculture was a primary subsistence activity (bowen, 1978; stothers and abel, 1989). faunal and floral analyses have shown that hunting, fishing, and gathering also contributed significantly to the subsistence of this population (bowen, 1991). the settlement pattern of the pearson village population was characterized by spring to fall village occupation and winter dispersal to small extractive camps (strothers and abel, 1989). analysis of late prehistoric population structure in the ohio valley region has shown that subpopulations were somewhat more differentiated than in the late archaic (fst = 0.078) and that genetic differentiation was not related to the pattern of geographic dispersion of subpopulations. it has been hypothesized that the difference in population structure between the late archaic and late prehistoric populations was due to the increased pace of cultural change in the late prehistoric period related to the introduction of tropical domesticates (maize, beans) and increased population growth (tatarek and sciulli, 2000). procedures for estimating age and sex for the late archaic and pearson village samples can be found in sciulli and aument (1987) and sciulli et al. (1996) respectively. measurement the bucco-lingual (bl) diameters of permanent antimetric teeth present in each individual were measured except for the third molars. the bl diameters are the distances between points of maximum curvature of the buccal and lingual surfaces of a tooth. each tooth was measured twice with time intervals between measures ranging from three weeks to four months. teeth with excessive wear or lesions which affected the bl diameter were not used. measurement of the late archaic sample was done with a helios dial caliper (instrument accuracy + 0.05 mm) and measurement of the pearson village sample was done with a mitutoyo digimatic caliper (instrument accuracy + 0.02 mm). statistical analyses preliminary analyses of the data consisted of obtaining descriptive statistics (mean, coefficient of variation, and a normality measure) and a measurement error determination for each tooth measure in both samples. measurement error is determined as σ|ri– li|/n, where r and l are the diameters of the right and left sides, i is the measure (1 or 2), and n is the sample size. the distributions of (ri–li) were tested for size dependence, anti-symmetry, and directional asymmetry. to test for size dependence plots of (ri–li) against a size measure (ri–li)/2, were obtained. although there was no evidence of size dependence for (ri–li) all measures were transformed by dividing the (ri–li) by the size measure for the analysis of variance (see below). anti-symmetry occurs when a structure in a groups of organisms is normally asymmetric but the side which has a greater development is variable (van valen, 1962). in extreme cases this will yield a bimodal distribution of the signed differences between the sides. in less extreme cases the distribution of signed differences will tend toward platykurtosis or possibly leptokurtosis if there is anti-symmetry only for larger deviations from equality (van valen, 1962). although anti-symmetry has not been reported for the human dentition the distributions of (ri – li) in the present samples were tested for departures from normality both graphically and numerically. dental asymmetry of prehistoric ohio valley american indians 36 37p. s. sciulli directional asymmetry occurs when there is a greater development of a feature on one side of an organism than the other side (van valen, 1962). the distribution of signed differences about the mean is generally normal but the mean is significantly greater or less than zero depending on which side shows the greater development. recently directional asymmetry has been noted in both the deciduous (townsend and farmer, 1998) and permanent (harris, 1992) dentitions of human populations. for the present samples the means of the distributions of sized differences between the sides are tested for differences from zero. in addition, directional asymmetry is tested in the analysis of variance (see below). the analysis of fluctuating dental asymmetry employed a two-way, mixed model analysis of variance (sides fixed, individuals random) with repeated measurements for each side (palmer and strobeck, 1986). the model is presented in table 1, where s is the number of sides (s = 2), j is the number of individuals, and m is the number of measures per side (m = 2). this analysis cannot partition out anti-symmetry (the variance components of fluctuating asymmetry and antisymmetry are contained in the non-directional variance component). however, the presence of anti-symmetry is tested in the evaluation of the (ri – li) distributions. non-directional asymmetry (mssj) is tested over measurement error and directional asymmetry is tested over non-directional asymmetry. size or shape variation is not tested in this study as the size correction transformation employed resulted in msj=0 for all measures. in the absence of anti-symmetry, fa can be quantified for a bl measure for a tooth as: s2i = (mssj msm)/2 comparisons of fa between the late archaic and pearson village samples used an f-test (ratio of s2i’s) with degrees of freedom for each s2i given by: (mssj msm) 2/((mssj) 2/j-1) + ((msm) 2/sj). associations between relative duration of the precalicification stage of tooth development (mizoguchi, 1980), relative tooth size variation (coefficient of variation), and fa (s2i) were tested using spearman’s rank correlation coefficient (sokal and rohlf, 1981). associations were obtained within each sample as well as between samples. all analyses were performed using ncss (hintze, 1992). results tables 2 and 3 contain the descriptive statistics and a measurement error estimate for the first and second bl measure in the maxillary and mandibular teeth of the late archaic and the pearson samples. overall relative variation of the bl diameters as measured by the coefficient of variation averages 2.6% higher in the pearson village sample. however, no variances are significantly different in the two samples (f-test; sokal and rohlf, 1981). mean bl diameters are consistently smaller in the pearson sample (3.4% overall) with the maxillary teeth (3.7%) somewhat smaller than the mandibular teeth (3.1%). tests of the differences in the means of the bl diameters (t-test; sokal and rohlf, 1981) revealed that the pearson village sample exhibited significantly smaller bl diameters for all teeth except the maxillary first molar and the lower canine, which showed no differences between the samples. the bl diameters are for the most part normally distributed in both samples. in the late archaic sample only the upper anterior premolar (both measures, right and left), upper lateral incisor (both measures, left side), and upper posterior premolar (both measures, right side) show departures from normality. in the pearson village sample only the upper second molar (both measures, right side) and lower lateral incisor (first measure, right side) show departures from normality. measurement error in the late archaic sample (0.060.09 mm) is in all cases greater than in the pearson village sample (0.03-0.04 mm) although the 95% confidence intervals overlap in most cases. the difference in measurement error is due primarily to the differences in the instrument accuracy (see measurement). table 4 contains the results of the analyses of the distributions of (ri – li) for the first and second measures in both samples. the late archaic sample exhibited some departures from normal (ri – li) distributions for four measures: the upper canine showed a slight (p=0.04) right skewness (measure 1), the lower lateral incisor showed a slight leptokurtosis (p = 0.02) for measurement 2, the upper first molar was leptokurtotic (p = 0.06) for the second measure only, and the lower second molar showed a slight leptokurtosis (p = 0.04) for the first measure and slight skewness (p = 0.005) and leptokurtosis (p = 0.01) for the second measure. in the pearson village sample, six teeth exhibited some departure from normality: the upper central incisor (p = 0.04) and the lower second molar (p = 0.03) showed slightly left skewed distributions for one of the two measures, the lower first molar showed a left skewness for both the first (p = 0.02) and second (p = source of variation df mean square expected mean square interpretation sides (s) (s-1) mss σ 2 m + m(σ 2 i +( j/s-1)σα 2 directional asymmetry individuals (j) (j-1) msj σ 2 m + m(σ 2 i +s σ j 2) shape or size variation remainder (s-1)(j-1) mssj σ 2 m + m σ 2 i non directional asymmetry measurement (m) sj(m-1) msm σ 2 m measurement error table 1. anova model; see text for discussion 36 37 0.002) measures, the upper first molar first measure (p = 0.03) and lower central incisor both measures (p = 0.03; p = 0.01) showed slightly leptokurtic distributions, and the lower lateral incisor showed a slight right skewness (p = 0.03) for both measures. because there is no indication of platykurtosis in any distribution of signed differences and since signed differences are not limited to larger deviations in the cases of leptokurtosis, overall anti-symmetry is judged to be absent in the present samples. since most deviations from normality are relatively minor these data appear to be suitable for the analysis of fa. archaic pearson measurement measurement tooth measure mean1 cv k2 error (limits) mean1 cv k2 error (limits) ui1 (n=43) r1 7.21 5.57 3.4 0.06 (0.05, 0.07) 6.97 6.26 0.6 0.04 (0.03, 0.05) r2 7.20 5.56 3.4 (n=53) 6.97 6.15 1.3 l1 7.27 5.60 1.6 0.07 (0.04,0.09) 7.00 6.71 0.4 0.04 (0.03, 0.05) l2 7.28 5.90 1.6 7.00 6.83 0.7 ui2 (n=44) r1 6.54 8.20 3.4 0.06 (0.04,0.08) 6.33 7.13 1.0 0.05 (0.03,0.06) r2 6.55 8.46 5.0 (n=53) 6.32 7.25 1.8 l1 6.59 8.12 7.52 0.07 (0.06,0.09) 6.30 7.95 6.5 0.04 (0.03,0.06) l2 6.61 8.13 8.62 6.28 7.96 6.4 uc (n=43) r1 8.84 7.41 1.0 0.08 (0.06,0.10) 8.42 7.20 3.2 0.04 (0.03, 0.06) r2 8.82 7.52 0.8 (n=66) 8.43 7.29 2.6 l1 8.81 7.59 0.2 0.07 (0.05,0.10) 8.42 7.30 1.1 0.03 (0.02,0.04) l2 8.81 7.33 1.0 8.43 7.29 0.8 up3 (n=45) r1 9.87 6.19 9.42 0.07 (0.05,0.09) 9.52 5.86 0.4 0.03 (0.02,0.04) r2 9.85 6.42 14.32 (n=65) 9.52 5.97 0.2 l1 9.83 6.47 17.42 0.06 (0.04,0.08) 9.48 6.03 0.9 0.04 (0.03,0.05) l2 9.83 6.61 17.82 9.48 6.11 1.0 up4 (n=37) r1 9.82 6.06 8.02 0.09 (0.06,0.11) 9.23 6.26 2.6 0.04 (0.03,0.05) r2 9.84 6.15 12.62 (n=52) 9.23 6.29 2.3 l1 9.80 5.78 2.5 0.06 (0.05,0.08) 9.21 6.81 1.1 0.04 (0.03,0.05) l2 9.78 5.78 3.2 9.21 6.71 1.0 um1 (n=45) r1 11.94 4.40 0.4 0.07 (0.04,0.10) 11.86 4.18 0.2 0.04 (0.03,0.05) r2 11.94 4.46 0.6 (n=72) 11.85 4.15 0.0 l1 11.88 4.33 0.1 0.08 (0.04,0.10) 11.85 4.09 0.8 0.03 (0.02,0.04) l2 11.91 4.16 0.2 11.85 4.10 0.9 um2 (n=44) r1 12.08 4.95 0.9 0.09 (0.07,0.10) 11.60 5.64 9.42 0.06 (0.05,0.07) r2 12.09 4.94 1.4 (n=64) 11.60 5.65 8.82 l1 12.09 4.97 0.2 0.08 (0.06,0.10) 11.64 5.91 1.8 0.05 (0.04,0.06) l2 12.10 4.64 0.2 11.65 5.94 1.5 1cv is coefficient of variation, k2 is omnibus normality test (d’agostino, 1990), error is σ|r-l|/n, limits is 95% limits of error. 2p < 0.05. table 2. descriptive statistics and measurement error for the buccolingual diameters of the maxillary teeth in the archaic and pearson samples dental asymmetry of prehistoric ohio valley american indians 38 39p. s. sciulli the mean of the distribution of signed differences is significantly different than zero for three teeth (t-test): the upper central incisor and the upper first molar in the archaic sample and lower first molar in the pearson village sample. in the late archaic sample the mean of the left upper central incisor is larger than the right (p = 0.03) while the right upper first molar is larger than the left (p = 0.002). for both of these teeth the differences are significant for the first measures only. in the pearson village sample the left lower first molar is larger than the right for both measures (p = 0.002; p = 0.003). directional asymmetry appears to be present at least for the pearson village lower first molar. tables 5 and 6 contain the results of the analysis of archaic pearson measurement measurement tooth measure mean1 cv k2 error (limits) mean1 cv k2 error (limits) li1 (n=39) r1 5.72 5.04 0.9 0.06 (0.05,0.07) 5.58 5.39 1.0 0.03 (0.02,0.04) r2 5.70 5.15 1.7 (n=61) 5.58 5.41 0.6 l1 5.70 5.64 2.6 0.06 (0.05,0.07) 5.59 5.42 0.1 0.04 (0.03,0.06) l2 5.68 5.57 2.3 5.59 5.44 0.2 li2 (n=44) r1 6.19 5.19 2.6 0.07 (0.06,0.08) 6.00 5.18 6.52 0.04 (0.03,0.05) r2 6.17 4.83 1.7 (n=60) 5.99 5.25 5.9 l1 6.18 4.63 1.7 0.07 (0.05,0.09) 5.97 5.12 0.3 0.04 (0.03,0.05) l2 6.14 4.75 0.2 5.96 5.09 0.8 lc (n=50) r1 7.86 7.01 0.3 0.06 (0.04,0.07) 7.72 7.16 3.4 0.03 (0.02,0.04) r2 7.85 7.10 1.0 (n=63) 7.73 7.15 4.0 l1 7.90 7.83 0.6 0.07 (0.04,0.09) 7.71 7.18 3.6 0.04 (0.03,0.04) l2 7.90 7.91 0.6 7.71 7.19 3.0 lp3 (n=45) r1 8.28 5.66 0.7 0.06 (0.05,0.08) 7.86 6.61 0.7 0.04 (0.03,0.05) r2 8.29 5.57 0.2 (n=71) 7.86 6.62 0.6 l1 8.30 5.39 2.7 0.07 (0.05,0.08) 7.87 5.90 0.2 0.04 (0.03,0.05) l2 8.31 5.34 2.6 7.87 5.88 0.6 lp4 (n=47) r1 8.65 5.32 5.2 0.07 (0.05,0.09) 8.30 5.91 0.6 0.04 (0.03,0.05) r2 8.66 5.50 3.9 (n=62) 8.29 5.85 1.2 l1 8.66 5.20 4.1 0.08 (0.06,0.09) 8.34 5.71 0.1 0.04 (0.03,0.05) l2 8.66 5.27 5.7 8.33 5.74 0.1 lm1 (n=53) r1 10.81 4.63 0.4 0.09 (0.07,0.11) 10.63 4.65 1.1 0.04 (0.03,0.05) r2 10.83 4.76 0.7 (n=84) 10.62 4.55 1.0 l1 10.81 4.72 0.0 0.07 (0.05,0.09) 10.69 4.61 1.9 0.04 (0.03,0.05) l2 10.83 4.65 0.4 10.68 4.60 2.5 lm2 (n=45) r1 10.79 5.80 3.9 0.07 (0.05,0.08) 10.35 4.93 1.0 0.04 (0.03,0.05) r2 10.80 5.87 3.5 (n=64) 10.35 5.00 1.0 l1 10.79 5.90 0.1 0.08 (0.06,0.10) 10.39 5.40 0.7 0.04 (0.03,0.05) l2 10.83 5.68 0.5 10.39 5.30 0.2 1cv is coefficient of variation, k2 is omnibus normality test (d’agostino, 1990), error is σ|r-l|/n, limits is 95% limits of error. 2p < 0.05. table 3. descriptive statistics and measurement error for the buccolingual diameters of the mandibular teeth in the archaic and pearson samples 38 39 variance (anova) for the maxillary and mandibular bl diameters respectively. the size correction transformation resulted in all cases in eliminating the size-shape (individual) source of variation (msj = 0). thus three sources of variation remain: sides, fluctuating asymmetry (= non-directional asymmetry as anti-symmetry is not present), and measurement error. directional asymmetry (sides) as measured by the anovas is significant in four late archaic teeth and two pearson village teeth. in the late archaic sample the right upper first molar is larger than the left, while for the upper lateral and central incisors and lower canines, the left sides are larger than the right (these four teeth also show the greatest (ri – li) differences in table 4 although all are not significant). in the pearson sample the lower left first molar is larger than the right while the lower right lateral incisor is larger than the left. fa is significantly greater than measurement error for all teeth in both samples. the late archaic sample exhibits significantly greater variance components (si 2) for the upper canine and lower lateral incisor while the pearson village sample exhibits greater variance components for the upper lateral incisor and first molar. measurement error (sm 2) as a percentage of (si 2 + sm 2) ranges between 5.2 and 39.2% for the late archaic sample with most values in the 5-15% range. in the pearson village sample, in which measurement error was lower, the corresponding values range between 2.7 and 12.1% with most values in the 3-10% range. spearman rank correlation coefficients between the coefficients of variation (cv), variance components of fa (si 2) and the relative time a tooth spends in soft tissue stages of crown development (mizoguchi, 1980) are contained in table 7. in the archaic sample fa is significantly correlated with cv (positive) while in the pearson village sample fa is significantly correlated with cv (positive) and time spent in soft tissue development (positive). late archaic fa is positively correlated with pearson village fa and cv but the pearson village fa is positively associated only with late archaic fa. discussion the late archaic and pearson village samples each exhibit directional and fluctuating asymmetry. while fa is present in all teeth in both samples, directional asymmetry is limited to four teeth in the late archaic sample (upper first molar, central and lateral incisors, and lower canine) and only two teeth in the pearson village sample (lower first molar and lateral incisor). harris (1992) and townsend and farmer (1998) have found directional asymmetry in the permanent and deciduous teeth respectively and have noted that there appears to be a tendency for right side dominance in one arch to be associated with left side dominance in the opposing maxilla mandible archaic pearson archaic pearson measure mean1 g1 g2 k 2 mean g1 g2 k 2 mean g1 g2 k 2 mean g1 g2 k 2 i1 r-l(1) -0.06 0.17 0.70 1.4 -0.03 -0.44 -0.17 1.9 0.02 0.31 1.24 3.1 -0.01 0.41 2.582 9.02 r-l(2) -0.072 0.19 1.10 2.5 -0.03 -0.692 -0.12 4.3 0.02 -0.24 1.59 3.7 -0.01 0.53 1.932 8.22 i2 r-l(1) -0.06 -0.02 0.03 0.1 0.04 -0.21 0.65 3.8 0.01 -0.12 0.23 0.4 0.04 0.692 1.07 7.3 r-l(2) -0.06 0.02 0.83 1.5 0.04 -0.42 0.99 1.7 0.04 0.33 2.312 6.22 0.03 0.672 -0.15 4.5 c r-l(1) 0.03 0.742 1.26 6.62 -0.01 -0.34 1.13 4.2 -0.04 -0.45 -0.16 1.8 0.01 0.07 0.90 2.1 r-l(2) 0.01 0.25 0.85 2.1 0.01 0.01 0.09 0.1 -0.05 -0.59 -0.08 3.1 0.02 -0.03 0.04 0.1 p3 r-l(1) 0.04 -0.32 0.01 0.9 0.04 -0.09 -0.37 0.4 -0.02 -0.18 0.96 2.1 0.00 -0.06 -0.15 0.1 r-l(2) 0.01 0.13 0.09 0.3 0.04 0.10 0.06 0.2 -0.02 -0.16 0.11 0.4 0.01 -0.03 -0.35 0.3 p4 r-l(1) 0.02 -0.37 -0.38 1.1 0.02 -0.07 1.42 3.3 -0.01 -0.51 0.73 3.5 -0.03 -0.56 0.97 5.6 r-l(2) 0.06 -0.60 -0.39 2.6 0.02 0.13 1.12 2.6 -0.01 0.45 1.40 4.7 -0.03 -0.50 0.20 3.0 m1 r-l(1) 0.062 0.55 0.93 4.2 0.01 0.17 0.04 0.5 0.00 -0.04 0.44 6.7 -0.062 -0.652 0.83 7.92 r-l(2) 0.03 -0.60 3.152 10.32 0.00 -0.42 1.652 7.12 0.01 0.28 0.69 2.1 -0.062 -0.882 0.79 11.62 m2 r-l(1) -0.01 0.37 -0.34 1.3 -0.04 -0.43 0.70 3.6 0.00 0.40 1.902 5.7 -0.04 -0.662 0.96 7.02 r-l(2) -0.01 0.20 0.30 0.8 -0.04 -0.28 0.72 2.5 -0.03 1.082 3.112 15.22 -0.04 -0.56 0.66 4.8 1g1 is skewness, g2 is kurtosis, and k 2 is omnibus normality test 2p < 0.05 table 4. descriptive statistics for the distribution of (ri-li) in the late archaic and pearson village samples dental asymmetry of prehistoric ohio valley american indians 40 41p. s. sciulli arch. this tendency for opposing arch dominance is not exhibited by either the late archaic or the pearson village sample. in the pearson village sample only mandibular teeth exhibited directional asymmetry (one right and one left dominant) while in the late archaic sample only one mandibular tooth (canine, l > r) and three maxillary teeth (first molar, r > l; central incisor, l > r; lateral incisor, l > r) exhibited directional asymmetry. one possible pattern exhibited by the late archaic and pearson village samples is all teeth that exhibit directional asymmetry are relatively early developing permanent teeth. harris (1992) proposed that the degree of directional asymmetry may be related to the level of developmental stress in a population and may result from differences in developmental timing between antimeres. sharma et al. (1986) suggested that environmental or genetic stress could lead to unilateral acceleration of mitotic activity in developing enamel organs yielding directional asymmetry. while early development was likely a stressful period for children in the late archaic and pearson village populations an association between increased stress (as measured by fa) and directional asymmetry is absent. of the six teeth that show directional asymmetry three (upper first molar and lateral incisor and lower lateral incisor) exhibit directional asymmetry in the sample that shows significantly less fa for that tooth. in the other three cases of directional asymmetry the samples archaic pearson tooth source df ssq4 msq f si 2 df df ssq4 msq f si 2 df ui1 sides 1 33.67 33.67 4.112 1 7.45 7.45 1.29 individuals 42 0 0 0 52 0 0 0 remainder 42 343.4 8.18 28.85* 3.95 39 52 299.2 5.75 43.20* 2.81 50 error 86 24.38 0.28 106 14.11 0.13 ui2 sides 1 37.58 37.58 4.042 1 25.23 25.23 1.50 individuals 43 0 0 0 52 0 0 0 remainder 43 399.6 9.29 21.45* 4.43 40 52 874.0 16.81 57.37* 8.263 50 error 88 38.13 0.43 106 31.01 0.29 uc sides 1 2.17 2.17 0.24 1 0.01 0.01 0 individuals 42 0 0 0 65 0 0 0 remainder 42 375.9 8.95 23.08* 4.282 39 65 273.5 4.21 38.27* 2.05 62 error 86 33.36 0.39 132 14.68 0.11 up3 sides 1 3.43 3.43 0.71 1 11.24 11.24 3.41 individuals 44 0 0 0 64 0 0 0 remainder 44 213.2 4.85 37.30* 2.36 37 64 211.0 3.30 47.14* 1.62 61 error 90 11.83 0.13 130 8.76 0.07 up4 sides 1 5.31 5.31 0.72 1 3.24 3.24 0.44 individuals 36 0 0 0 51 0 0 0 remainder 36 266.7 7.41 28.50* 3.58 34 51 376.8 7.39 70.9* 3.64 50 error 74 18.95 0.26 104 10.84 0.10 um1 sides 1 5.38 5.38 5.032 1 0.18 0.18 0.11 individuals 44 0 0 0 71 0 0 0 remainder 44 46.98 1.07 4.13* 0.40 25 71 109.0 1.53 24.50* 0.742 65 error 90 22.34 0.26 144 9.02 0.06 um2 sides 1 0.19 0.19 0.04 1 9.05 9.05 1.87 individuals 43 0 0 0 63 0 0 0 remainder 43 182.7 4.25 19.31* 2.02 39 63 303.6 4.82 43.81* 2.36 60 error 88 19.15 0.22 128 13.52 0.11 * p < 0.001 1 p ~ 0.05 2 0.05 > p > 0.025 3 pearson si 2 >archaic si 2 f=1.56, p~0.025 4 archaic si 2 > pearson si 2 f=2.09, p~0.005 5 pearson si 2 >archaic si 2 f=1.85, p~0.025 6 ssq, msq, and si 2 x 104 table 5. analysis of variance for maxillay teeth in the late archaic and pearson village 40 41 show no differences in fa. although scenarios could be proposed to explain these data on directional asymmetry, for example that the presence of increased fa masks the presence of directional asymmetry, i think townsend and farmer (1998:253) summarized the current situation very well when they stated: although it would seem that directional dental asymmetry is not merely a statistical artifact, its exact nature and causes remain to be solved. so too does the question of whether there is any relationship between fluctuating and directional forms of dental asymmetry. fluctuating asymmetry is present for all teeth in both samples. however, contrary to expectations concerning the differences in environmental stress levels between foragers and agriculturalists, the pearson village agriculturalists do not show a greater level of fa compared to the late archaic foragers. the average fa (si 2) for all 14 teeth in the late archaic sample is virtually identical to that in the pearson village sample, 2.65 and 2.56 (x 10-4) respectively. only four teeth show significant differences between the samples with the late archaic sample showing greater fa for two teeth (upper canine and lower lateral incisor) and the pearson sample showing greater fa also for two teeth (upper first molar and lateral incisor). the lack of an indication of increased developmental stress in the pearson village agriculturalists is likely due to the fact that maize archaic pearson tooth source df ssq4 msq f si 2 df df ssq4 msq f si 2 df li1 sides 1 6.35 6.35 0.80 1 2.14 2.14 0.44 individuals 38 0 0 0 60 0 0 0 remainder 38 192.9 5.08 17.39 2.40 34 60 291.8 4.86 19.45 2.30 54 error 78 22.70 0.29 122 30.08 0.25 li2 sides 1 5.53 5.53 0.88 1 15.75 15.75 5.961 individuals 43 0 0 0 59 0 0 0 remainder 43 267.7 6.26 13.60 2.902 37 59 156.0 2.64 15.62 1.24 51 error 88 40.90 0.46 120 20.27 0.17 lc sides 1 13.76 13.76 3.60 1 2.13 2.13 0.62 individuals 49 0 0 0 62 0 0 0 remainder 49 187.3 3.82 11.31 1.74 40 62 211.2 3.41 28.49 1.76 57 error 100 33.77 0.34 126 15.08 0.12 lp3 sides 1 2.96 2.96 0.57 1 1.24 1.24 0.20 individuals 44 0 0 0 70 0 0 0 remainder 44 230.2 5.23 24.91 2.72 41 70 430.5 6.15 43.93 3.01 67 error 90 18.50 0.21 142 19.44 0.14 lp4 sides 1 0.39 0.39 0.09 1 7.44 7.44 1.54 individuals 46 0 0 0 61 0 0 0 remainder 46 208.9 4.54 15.66 2.12 40 61 293.9 4.82 41.76 2.47 58 error 94 27.16 0.29 124 14.31 0.12 lm1 sides 1 0.01 0.01 0.0 1 25.32 25.32 10.513 individuals 52 0 0 0 83 0 0 0 remainder 52 149.1 2.87 13.04 1.32 44 83 199.7 2.41 26.78 1.16 77 error 106 23.76 0.22 168 14.42 0.09 lm2 sides 1 0.80 0.80 0.14 1 10.47 10.47 2.08 individuals 44 0 0 0 63 0 0 0 remainder 44 260.0 5.91 29.55 2.86 41 63 316.8 5.03 62.88 2.47 60 error 90 18.17 0.20 128 10.61 0.08 10.025 > p > 0.025 2archaic si 2 > pearson si 2 3p > 0.05 4ssq, msq, and si 2 x 104 table 6. analysis of variance for mandibular teeth in the late archaic and pearson village dental asymmetry of prehistoric ohio valley american indians 42 43p. s. sciulli agriculture was adopted late in prehistory (ca. 1000 bp) by ohio valley and lower great lakes populations and a heavy reliance on hunting and gathering as well as agriculture characterized the entire late prehistoric period (ca. 1000-350 bp). the transition to a full agricultural subsistence was probably never completely realized in this region. a survey of skeletal and dental stress indicators in late archaic and late prehistoric populations of the region suggests that while stress is indicated to some degree for all populations the relatively low prevalence of pathological conditions indicates that stress levels were not elevated. aside from dental lesions which increase dramatically in the late prehistoric period, other pathological conditions as well as indicators such as growth rates and adult stature show only minor differences among the populations. these results in toto suggest that general life-style patterns did not vary greatly in the region over this time span and even after the introduction of maize agriculture, overall environmental stress was not elevated to the degree that would result in increased fluctuating dental asymmetry (sciulli and oberly, 2002). the similarity between the late archaic and pearson village samples also extends to the relationship of fa, relative variation (cv) and time spent in soft tissue development. in both the late archaic and pearson village samples fa (si 2) is significantly correlated at about the same magnitude with relative variation, teeth displaying greater crown size variability also tend to show greater fa. relative variation is strongly correlated between the two samples and fa is significantly correlated as well. 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their ease of measurement and their repeatability—not on any true biological criterion. researchers have investigated other sorts of tooth crown variables, notably biggerstaff (1969a,b) who devised an array of distances, angles, and areas that can be measured on the occlusal table of teeth in the buccal segments. as with some previous researchers (e.g., biggerstaff, 1975; corruccini, 1979; townsend, 1985; townsend et al., 2003; bailey, 2004), we were motivated to explore the patterns of variation of the occlusal tables of maxillary molars, largely to investigate whether additional information can be gained compared to the conventional lengths and widths of crowns. maxillary molars were chosen because their occlusal morphology is a bit simpler than in the mandible and because there is considerable research by embryologists on how the number and arrangement of enamel knots determines a tooth’s occlusal morphology. considerable importance now is attributed to primary and secondary enamel knots that direct the folding of the inner enamel epithelium (iee) that determines a tooth’s crown morphology (jernvall et al., 1994; thesleff et al., 2001). enamel knots are transitory condensations of the iee that cause growth of that site to cease (thereby creating a presumptive cusp tip) while at the same time promoting cell proliferation of adjacent regions that causes the iee to fold (jernvall et al., 1994, 1998, 2000; a study of cusp base areas in the maxillary permanent molars of american whites dustin p. dinh and edward f. harris* college of dentistry, university of tennessee, memphis, tennessee abstract the focus of this descriptive study was to explore the patterns of variation of base crown areas for the four major cusps on the maxillary first and second permanent molars in a cohort of contemporary north american whites of western european descent. a computer-assisted photogrammetric method was used to measure two-dimensional areas of the cusps. ranking of mean cusp size was the same for m1 and m2, namely protocone > paracone > metacone > hypocone. in concert with field theory, size decreased while variability (cv) increased across this same sequence. overall area of m1 (97 mm2) is 13% larger than m2 (86 mm2) in this sample. most cusps exhibited significant sexual dimorphism, with greater differences for the distal cusps within a tooth and from m1 to m2. intercorrelations of cusp areas were notably low (r2 < 15%) both within and between m1 and m2, suggesting considerable independence in formative rates of each cusp and low morphological integration of these constituents of the occlusal table. limited comparative material in the literature suggests that cusp areas may valuably extend the quantitative comparisons for genetic and biological studies beyond conventional tooth crown width and length. dental anthropology 2005;18:22-29. luuko et al., 2003). regional differences in proliferative rates account for the angularity of cusps, at least at the enamal-dentin interface. purpose of the present study, which is predominantly descriptive and exploratory, was to characterize the basal cusp areas of the main cusps on the maxillary first and second molars in a sample of north american whites. basal cusp area is a term coined by biggerstaff (1969b) to refer to the two-dimensional area defined by a cusp in occlusal view, demarcated by the major developmental grooves (e.g., zeisz and nuckolls, 1949) and ranging to the periphery of the occlusal table. in fact, biggerstaff actually used polygons defined by several anatomic landmarks as proxies for the anatomic configuration of a cusp area because of the technical difficulties involved in computing the area of a free-form object. wood and colleagues (wood and abbott, 1983; wood et al., 1983) used a planimeter to measure basal cusp areas. more recently, macho and moggi-cecchi (1992), bailey (2004) and others used computer systems that obviate the tedium of semi-mechanical approaches. materials and methods data were collected from full-mouth dental casts of adult north american whites. individuals were phenotypically normal. there were 112 females and 88 males *correspondence to: edward f. harris, department of orthodontics, college of dentistry, the health science center, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu 22 23 in the sample (200 individuals total). cusp base areas were measured on the maxillary first and second permanent molars. there were very few third molars in this sample because of the common clinical practice of extracting them prophylactically. not every tooth was usable because of dental restorations that obscured key morphological features. restorations were, by far, the predominant reason for excluding teeth, and the comparatively high frequency of restorations on the first molars accounts for the larger usable samples for variables on m2. a high-resolution digital photograph was taken of each molar individually (described in harris and dinh, n.d.). these images were stored on a computer, and data were collected using proscan 5.0 (sas institute, nc). cusp outlines were traced using the computer’s mouse in a fashion analogous to using a planimeter (wood and abbott, 1983; wood et al., 1983). the four main cusps were measured individually (fig. 1). the fifth cusp (the metaconule1; harris and bailit, 1980) was also measured, though it occurred too infrequent to permit statistical analysis. when the hypocone was absent, it was scored as “missing,” not zero. the base area of carabelli’s trait (e.g., kraus, 1959; turner and hawkey, 1998) was included as part of the area of the protocone because we found it difficult to distinguish the occlusal component of carabelli’s trait from that of the protocone except when this cingular feature exhibited a large separate cusp. inclusion of carabelli’s trait accounts for the protocone’s large coefficient of variation, especially on m2 where the trait (and trait size) is more variable. results descriptive statistics (table 1) show that the modal cusp base areas is the same as the phylogenetic acquisition of the cusps, namely that the protocone is the largest and the sequence of reduction is protocone > paracone > metacone > hypocone, which is the same ranking of sizes described in texts on contemporary anatomy (e.g., zeisz and nuckolls, 1949; ash, 1993). two rankings are of note on the first molar: (1) size of the cusp base area diminishes sequentially from the protocone through the hypocone and (2) size variability (cv) increase in this same sequence. the same patterns of variability hold for the second molar (recalling that we included carabelli’s trait as part of the protocone base area). in addition, as predicted from dental field theory (dahlberg, 1951), cusp areas on m2 (the later forming tooth) are more variable than homologous features on m1. tests for sexual dimorphism (table 1) show that males characteristically have larger cusp base areas, though not invariably so. the protocone on m1 is not dimorphic (p = 0.71) nor is the base area for the metacone (p = 0.20). the other two cusps on m1 and all four cusps on m2 exhibit statistically significant sexual dimorphism. on a percentage basis, the overall crown area of m1 is about 5% larger in males (p < 0.01) and this difference increases to about 10% for the later-forming m2 (p < 0.01). correlations were computed between the cusp areas (table 2). this was done pairwise so the absence of the hypocone on about half of the second molars did not affect the other sample sizes. the weakness of the correlations seems striking; the strongest correlations are only on the order of 0.3 to 0.4 and most are appreciably lower. these low correlations are indicative of “loose” morphological integration of the cusps that compose the occlusal tables (olson and miller, 1958). correlations between cusps on m1, the pole tooth, achieve statistical significance because of the fairly large sample sizes, but they explain little of the variation between areas (all with r2 < 15%). there is no discernible patterning of the correlations within m1 or within m2. correlations are even smaller for the m2 comparisons than on m1. comparing between m1 and m2, the correlations are no stronger between the homologous cusps than for the other pairings, and, again, the explained variation (r2) between cusp areas on the two molars is invariably less than 15%. fig. 1. terminology used for the maxillary molars. this cusp numbering system was introduced by gregory (1916); numbering is only used as a shorthand device since this numbering sequence is not the mineralization sequence noted by embryologists (e.g., kraus and jordan, 1965). 1mizoguchi (1988:45) correctly notes that this cusp actually is the “tuberculum accessorium posterius externum” described by selenka (1898, cited in korenhof, 1960) that mizoguchi himself terms the “distobuccal accessory marginal tubercle.” the true metaconule is a different feature. cusp areas of maxillary molars 24 25 the occlusal table of m2 is about 13% smaller than that of the first molar (table 3), but this summary statistic hides some interesting variations. the mesial pair of cusps (the protocone and paracone) actually is significantly larger on m2 than m1. in contrast, the decreases in average cusp sizes are dramatic for the metacone and hypocone; both basal areas are about one-third smaller on m2. these distal cusps are, however, smaller absolutely than their mesial counterparts, so, the m1-to-m2 difference for the whole occlusal table is a decrease of about 13%. we also included a molar-by-sex interaction term in the anova tests in table 3, but it was not significant for any variable, which confirms that the size gradients between m1 and m2 are equivalent (proportionate) in males and females. discussion there are several contributors to a cusp’s basal area, though little is known about their specific control mechanisms. the number and presumptive spatial relationships of cusps are defined by primary and secondary enamel knots (thesleff and jernvall, 1997; jernvall and thesleff, 2000; sharpe, 2001; thesleff et al., 2001). the histological occurrence of enamel knots has been known for over a century (reviewed in butler, 1956), but their function was recognized only recently. enamel knots are sites in the stellate reticulum adjacent to the inner enamel epithelium. they are sites without mitotic activity that initiate cusp tip formation at the enamel–dentin interface. while enamel knots define the number and fundamental arrangement of cusps, there is considerable growth of the tooth from the cap stage (when knots develop) into the bell stage when amelogenesis progresses down the slopes of the cusps and, eventually, the intercuspal regions mineralize, thereby “freezing” the distances between cusps, at least at the enamel-dentin junction. information on the growth of the teeth (primarily intercuspal distances between the early-forming stable cusps) shows that there are considerable increases in dimensions of the occlusal table during these phases and that the rates of growth differ among cusps, among teeth, and with time (e.g., butler, 1967a,b, 1968). butler’s data (1967b) for um1 show that the paracone-metacone distance increases from about 1 mm when the cusps are first discernible to about 4 mm when they have both mineralized. butler comments that the intercuspal distances table 1. descriptive statistics and tests for sexual dimorphism1 total male female variable n x sd cv n x sd n x sd %sd f ratio prob > f maxillary first molar protocone 160 32.23 4.78 14.83 68 32.40 5.34 92 32.11 4.34 0.9 0.14 0.7109 paracone 160 24.06 3.41 14.18 68 25.36 3.46 92 23.09 3.05 9.8 19.25 < 0.0001 metacone 160 21.46 3.09 14.41 68 21.83 3.14 92 21.19 3.05 3.0 1.65 0.2005 hypocone 160 19.35 3.83 19.80 68 20.26 4.28 92 18.68 3.33 8.5 6.90 0.0094 metaconule 1 4.59 --0 --1 4.59 ----crown area 160 96.94 10.45 10.78 68 99.85 11.30 92 94.78 9.25 5.3 9.70 0.0024 maxillary second molar protocone 183 36.97 7.48 20.22 78 38.50 7.98 105 35.83 6.90 7.5 5.88 0.0163 paracone 183 25.47 3.65 14.32 78 26.21 3.49 105 24.92 3.68 5.2 5.78 0.0172 metacone 183 16.07 3.15 19.58 78 16.90 3.56 105 15.46 2.66 9.3 9.81 0.0020 hypocone 102 14.58 5.29 36.28 43 16.06 5.86 59 13.50 4.59 18.9 6.09 0.0153 metaconule 2 20.51 11.43 -2 20.51 11.43 0 -----crown area 183 85.67 11.90 13.90 78 90.37 14.28 105 82.18 8.26 10.0 23.85 < 0.0001 1descriptive statistics are: sample size (n), arithmetic mean ( x ), standard deviation (sd) and coefficient of variation (cv). ”%sd” is percent sexual dimorphism calculated as x -x x 100m f f     . the f ratios test for sexual dimorphism. d.p. dinh and e.f. harris 24 25 have the highest growth rates. “the cusp tips separate more rapidly than can be accounted for by enlargement of the bases on which the cusps stand” (1967b:990). in other words, the cusps migrate toward the sides of the tooth (buccally and lingually) with growth because of faster mitotic rates in the central basin. additional increases in intercuspal distance and basal cusp area occur after bridging of the cusps because amelogenesis is eccentric, meaning that enamel deposition proceeds “in such a manner that the completed enamel apices are dispersed linguobuccally more than mesiodistally relative to their dentine analogs” (kraus, 1952). it also is well documented that enamel deposition (amelogenesis) initiates on different cusps at different times and bridging between cusps occurs at different times (kraus and jordan, 1965), so the definitive size of cusps at the enamel-dentin junction reflects a collage of events ranging a span of time—where it is likely that this “span” varies among tooth types and among individuals and among populations (bailey, 2004). indeed, data collected by kraus and jordan (1965) and by moss and applebaum (1962) clearly shows these allometric patterns of growth. similarly, rosenzweig’s (1970) study of crown index (bl/md times 100) confirms intergroup differences in completed tooth crown shape, along with the trend for males to have larger indices (i.e., greater bl width in comparison to md length) than females within a group. viewed occlusally, cusp area includes the sloping margins of the crowns, down to what, clinically are table 2. pairwise correlations between cusp areas within and between the two maxillary molars1 variable variable n r2 r p value tau p value within first molar m1 protocone m1 paracone 160 0.042 0.205 0.0095 0.158 0.0031 m1 protocone m1 metacone 160 0.078 0.278 0.0004 0.166 0.0019 m1 protocone m1 hypocone 160 0.059 0.243 0.0020 0.203 0.0001 m1 paracone m1 metacone 160 0.090 0.301 0.0001 0.177 0.0009 m1 paracone m1 hypocone 160 0.110 0.332 < 0.0001 0.223 < 0.0001 m1 metacone m1 hypocone 160 0.132 0.364 < 0.0001 0.241 < 0.0001 within second molar m2 protocone m2 paracone 183 0.080 0.283 0.0001 0.176 0.0004 m2 protocone m2 metacone 183 0.001 0.029 0.6974 0.025 0.6198 m2 protocone m2 hypocone 102 0.032 0.179 0.0719 0.056 0.4050 m2 paracone m2 metacone 183 0.077 0.278 0.0001 0.182 0.0003 m2 paracone m2 hypocone 102 0.005 0.073 0.4669 0.080 0.2313 m2 metacone m2 hypocone 102 0.029 0.171 0.0856 0.120 0.0749 between molars m1 protocone m2 protocone 141 0.050 0.224 0.0076 0.163 0.0041 m1 protocone m2 paracone 141 0.091 0.302 0.0003 0.215 0.0002 m1 protocone m2 metacone 141 0.035 0.187 0.0264 0.139 0.0148 m1 protocone m2 hypocone 76 0.060 0.246 0.0325 0.190 0.0151 m1 paracone m2 paracone 141 0.107 0.327 0.0001 0.219 0.0001 m1 paracone m2 protocone 141 0.004 0.064 0.4498 0.030 0.5953 m1 paracone m2 metacone 141 0.065 0.255 0.0023 0.170 0.0028 m1 paracone m2 hypocone 76 0.043 0.208 0.0714 0.087 0.2679 m1 metacone m2 protocone 141 0.022 0.147 0.0821 0.092 0.1063 m1 metacone m2 paracone 141 0.121 0.348 < 0.0001 0.241 < 0.0001 m1 metacone m2 metacone 141 0.155 0.394 < 0.0001 0.318 < 0.0001 m1 metacone m2 hypocone 76 0.123 0.351 0.0019 0.205 0.0089 m1 hypocone m2 protocone 141 0.002 0.045 0.5943 0.011 0.8459 m1 hypocone m2 paracone 141 0.050 0.224 0.0076 0.180 0.0016 m1 hypocone m2 metacone 141 0.108 0.329 0.0001 0.238 < 0.0001 m1 hypocone m2 hypocone 76 0.149 0.386 0.0006 0.311 < 0.0001 1the pearson product-moment correlation coefficients (r) and coefficients of determination (r2) are listed, along with kendall’s tau, a nonparametric measure of association. sample sizes are number of pairs of observations. cusp areas of maxillary molars 26 27 termed the heights of contour (zeisz and nuckolls, 1949; ash, 1993). these heights correspond to the bulges (convexities) on the crowns that operationally define the maximum mesiodistal and buccolingual tooth crown dimensions that have been used so extensively in the anthropological study of teeth (wolpoff, 1971; swindler, 1976, 2002; kieser, 1990). these maxima occur at various heights of the crowns depending on tooth type. on human molars, maximum mesiodistal height occurs near the midsection of the crown’s height, while buccolingual width occurs close to the gingival margin. some portions of these crown heights are included in an occlusal projection of a cusp’s area even though the collum of the crown mineralizes at some time appreciably later than the occlusal table (moorrees, fanning and hunt, 1963). macho and spears (1999) note that there is a mesiodistal gradient among the molars such that first molars have considerably thinner enamel than second and third molars and that the first molar tends to have more sloping (less upright) sides of the crown, buccally and lingually, than the distal molars. one would suppose that these buccal and lingual slopes on m1 would reposition the maximum heights of contour apically and have the effect of increasing occlusal areas when viewing the crown occlusally. little is known about growth control mechanisms that regulate development of the cervical loop—that region of the crown apical to the occlusal table that progressively undergoes dentinogenesis—and, subsequently, amelogenesis until the crown is complete at the cementoenamel junction (keene, 1982). in the present study, we were struck by the low levels of correlation among the basal cusp areas (table 2). while all of the correlations were positive and many achieved statistical significance because of the large sample sizes, they do not account for much of the observed variation (all r2 < 15%). the typical interpretation of low biological correlations is that the variables have separate developmental causes (separate etiologies) and that seems to be the case here. the conventional measurement of crown size (e.g., goose, 1963) has traditionally been viewed as a composite measure of the constituent basal cusp area. the occlusal morphology of a tooth, especially that of a molar, is so distinctive that there rarely is any question as to its arcade, side, or placement in the tooth row. it seems to us that these features have bolstered the supposition that the constituent cusp areas are strongly tied to overall tooth size (also see garn, 1977). the present study suggests a different scenario: growth of the basal cusp areas is only weakly coordinated. low correlations imply weak morphological integration among the main cusps (olson and miller, 1958), seemingly because each cusp’s growth depends on (largely) independent regulatory mechanisms (salazar-ciudad and jernvall, 2002). low correlations among the cusps—weak “morphological integration” of the regions of the occlusal table— are in fact the rule rather than the exception. biggerstaff commented on these weak associations in his landmark work in this area (1975), and subsequent researchers (garn, 1977; corruccini and potter, 1981; townsend, 1985; townsend et al., 2003) have each remarked on it. the consensus is that the constituent regions of the occlusal table show weaker levels of intercorrelation, greater coefficients of variation, greater left-right asymmetry, and lower genetic control (greater environmental variation) than overall crown size. townsend et al. (2003:350) studied intercuspal distances instead of areas, but they concluded equivalently that, “our finding of high phenotypic variation in intercuspal distances with only moderate genetic contribution is consistent table 3. results of mixed-model anova testing for sexual dimorphism and size difference between cusps on m1 and m21 sex difference m1-m2 difference percent variable df f-ratio prob > f df f-ratio prob > f difference protocone 1, 139 2.37 0.1258 1, 139 51.43 < 0.0001 +12.8 paracone 1, 139 22.50 < 0.0001 1, 139 14.09 0.0003 +5.5 metacone 1, 139 6.86 0.0098 1, 139 375.61 < 0.0001 -33.5 hypocone 1, 74 8.83 0.0040 1, 74 126.34 < 0.0001 -32.7 crown area 1, 139 21.27 < 0.0001 1, 139 298.91 < 0.0001 -13.2 1sex was included in the model to account for the observed sexual dimorphism in cusp areas. sex is a fixed effect while the cusp areas on m1 and m2 are a repeated-measure in the anova tests. d.p. dinh and e.f. harris 26 27 with substantial epigenetic influence on the progressive folding of the internal enamel epithelium, following formation of the primary and secondary enamel knots.” most of the basal cusp areas on both m1 and on m2 are sexually dimorphic in the present sample of american whites. in fact, percentage dimorphism (table 1) tends to be greater for these areas than for corresponding sex differences in overall mesiodistal and buccolingual tooth dimensions measured on the same teeth, namely 2.8% and 1.8% for m1 and m2 dimensions mesiodistally and 5.0% and 2.9% for m1 and m2 buccolingually (harris and burris, 2003). again, we attribute the high variability and absence of sexual dimorphism of the protocone on m1 to including the variable size of carabelli’s trait with this cusp. it is of note that the degrees of sexual dimorphism are larger for the second molar whose occlusal table mineralizes around four and a half years of age (harris and buck, 2002) than on m1 where mineralization occurs by one-half year. for both molars, the morphologically variable hypocone shows a high degree of sexual dimorphism. this difference in area of the hypocone is part of the morphogenetic field effect, where there is a steeper decline in average size (and occurrence) in females than males (e.g., moorrees, 1957; jacobson, 1982). these findings (table 1) are at odds with biggerstaff’s finding (1975) that there were “suggestions” of sexual dimorphism in cusp areas but that they seldom attained statistical significance. biggerstaff did not provide statistics in this regard, but his graphs suggest that, indeed, most means for males and females were within one standard deviation of each other. subsequent studies of intercuspal distances (garn, 1977; townsend, 1985; townsend et al., 2003) also comment on the low level of sexual dimorphism in these constituent components of crown size. biggerstaff’s results were hampered by partitioning his sample into small groups based on molar cusp configurations, and he did not actually measure cusp area. instead, he calculated the areas of polygons defined by several landmarks, none of which was truly peripheral on the occlusal table, so his values variably underestimate “basal cusp area” as viewed occlusally. the computer-assisted method used in the present study is comparable to that used by macho and moggicecchi (1992) to measure cusp areas of maxillary molars of south african blacks (fig. 2). analogous to studies of conventional crown diameters (e.g., richardson and malhotra, 1975; jacobson, 1982), the cusp areas of these sub-saharan blacks are obviously larger than the present sample of north american whites of western european descent, but not uniformly so. for several cusp areas there is greater sexual dimorphism in the blacks. protocone size is the same in the two groups for m1 and larger in whites on m2. paracone areas appear to be equivalent in the two groups, while the metacone and hypocone are appreciably larger in the blacks. since there is not just a difference in scale between these two groups, additional studies may provide informative patterns of size variation well beyond the simple blacks > whites suggested by overall crown sizes (e.g., harris and rathbun, 1991). prior studies (e.g., macho and moggi-cecchi, 1992) have asked the somewhat rhetorical question of whether there is uniform (isometric) scaling of cuspal features from m1 to m2 to m3. obviously, the decisive answer is “no.” there are obvious allometric differences. in the present study that compares just m1 and m2 (table 3), there are highly significant changes for all four-cusp areas. an isometric reduction from m1 to m2 would mean that m2 is merely a “scaled-down” version of m1, the pole tooth. instead, the protocone and paracone have significantly larger basal areas on m2, while the metacone and hypocone are clearly smaller on m2. the fig. 2. average basal cusp areas for the present sample of american whites compared to data published by macho and moggi-cecchi (1992) for south african blacks. error bars are +1 standard deviation. overall crown area was about 3% larger in blacks than whites for m1 and 11% larger for m2. cusp areas of maxillary molars ��������� �������� �������� �������� � �� �� �� �� � �� � �� � �� � � � �� �� �� �� � � �� �� ���������� ���������� ���������� ���������� ��������� �������� �������� �������� � �� �� �� �� � �� � �� � �� � � � �� �� �� �� � � �� �� ���������� ���������� ���������� ���������� 28 29 metacone and hypocone (table 3) differ in their degrees of size reduction, perhaps because the metacone is part of the molar’s comparatively stable trigon, while the hypocone is the sole cusp of the talon in humans (osborn, 1907; gregory, 1922). the metacone’s variability seems to be expressed wholly as size variation; there was no instance on m1 or m2 where this cusp was absent. in contrast, the hypocone was always present on m1 in some form, but was absent in about half (47%; 66/140) of the m2 sample. consequently, the size variation calculated here is just for the half of the m2 where the hypocone is present. other studies that have quantified occlusal areas also have commented on the especial variability of the hypocone (e.g., biggerstaff, 1975; peretz et al., 1998; yamada and brown, 1998). to note just that m2 has a smaller occlusal table than m1 (a 13% reduction on average) hides the considerable variability within the constituent cusps. we have explored here some of the biological features of cusp areas on maxillary molars. our motivation was to extend the battery of biologically (and anthropologically and genetically) useful features that can be studied beyond the hackneyed use of maximum md and bl crown diameters. moreover, work by embryologists (e.g., jernvall and thesleff, 2000; salazarciudad and jernvall, 2002) suggests that regulation of events that define morphology of the occlusal table probably are different than those acting later to form the collum of the crown where conventional diameters are measured, thus providing additional and different biological information. in contrast to the enormously timeand effort-intensive computer methods initiated by biggerstaff (e.g., 1969a,b), the computer hardware and software now available make the study of crown components comparatively quite feasible. acknowledgment research supported by nidcr de-07258. literature cited ash mm jr. 1993. wheeler’s dental anatomy, physiology and occlusion, 7th ed. philadelphia: wb saunders. bailey se. 2004. a morphometric analysis of maxillary molar crowns of middle-late pleistocene hominins. j hum evol 47:183-198. biggerstaff rh. 1969a. the basal area of posterior tooth crown components: the assessment of within tooth variations of premolars and molars. am j phys anthropol 31:163-170. biggerstaff rh. 1969b. electronic methods for the analysis of the human post-canine dentition. am j phys anthropol 31:235-242. biggerstaff rh. 1975. cusp size, sexual dimorphism, and heritability of cusp size in twins. am j phys anthropol 42:127-139. butler pm. 1956. ontogeny of the molar pattern. biol rev 31:30-70. butler pm. 1967a. the prenatal development of the human upper permanent molar. arch oral biol 12: 551-563. butler pm. 1967b. relative growth within the human first upper permanent molar during the prenatal period. arch oral biol 12:983-992. butler pm. 1968. growth of the human second lower deciduous molar. arch oral biol 13:671-682. corruccini rs. 1979. molar cusp-size variability in relation to odontogenesis in hominoid primates. arch oral biol 24:633-634. corruccini rs, potter rhy. 1981. developmental correlates of crown component asymmetry and occlusal discrepancy. am j phys anthropol 55:21-31. dahlberg aa. 1951. the dentition of the american indian. in: laughlin ws, editor. the physical anthropology of the american indian. new york: viking fund inc., p 138-176. garn sm. 1977. genetics of tooth development. in: mcnamara ja, editor. the biology of occlusal development. ann arbor, mi: craniofaical growth series, p 61-88. goose dh. 1963. dental measurements: an assessment of its value in anthropological studies. in: brothwell dr, editor. dental anthropology. oxford: pergamon press, p 125-148. gregory wk. 1916. studies on the evolution of the primates. i. the cope-osborn ‘theory of trituberculy’ and the ancestral molar patterns of the primates. bull am mus natl hist 35:239-257. gregory wk. 1922. the origin and evolution of the human dentition. baltimore: williams & wilkins company. harris ef, bailit hl. 1980. the metaconule: a morphologic and familial analysis of a molar cusp in humans. am j phys anthropol 53:349-358. harris ef, buck a. 2002. tooth mineralization: a technical note on the moorrees-fanning-hunt standards. dental anthropology 16:15-20. harris ef, burris bg. 2003. contemporary permanent tooth dimensions, with comparisons to g. v. black’s data. j tenn dent assoc 83:25-29. harris ef, dinh dp. n.d. intercusp relationships of the maxillary first and second molars in american whites. am j phys anthropol [in press]. harris ef, rathbun ta. 1991. ethnic differences in the apportionment of tooth sizes. in: kelley ma and larsen cs, editors. advances in dental anthropology. new york: alan r. liss, inc., p 121-142. jacobson a. 1982. the dentition of the south african negro. anniston, al: higginbotham, inc. jernvall j, aberg t, kettunen p, keranen s, thesleff i. 1998. the life history of an embryonic signaling center: bmp-4 induces p21 and is associated with d.p. dinh and e.f. harris 28 29 apoptosis in the mouse tooth enamel knot. development 125:161-169. jernvall j, keränen sv, thesleff i. 2000. evolutionary modification of development in mammalian teeth: quantifying gene expression patterns and topography. proc natl acad sci u s a 97:14444-14448. jernvall j, kettunen p, karavanova i, martin lb, thesleff i. 1994. evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation: non-dividing cells express growth stimulating fgf-4 gene. int j dev biol 38:463-469. jernvall j, thesleff i. 2000. reiterative signaling and patterning during mammalian tooth morphogenesis. mech dev 92:19-29. keene hj. 1982. the morphogenetic triangle: a new conceptual tooth for application to problems in dental morphogenesis. am j phys anthropol 59:281-287. kieser ja. 1990. human adult odontometrics: the study of variation in adult tooth size. new york: cambridge university press. korenhof caw. 1960. morphogenetical aspects of the human upper molar. utrecht: uitgeversmaatschappij neerlandia. kraus bs. 1952. morphologic relationships between enamel and dentin surfaces of the lower first molar teeth. j dent res 31:248-256. kraus bs. 1959. occurrence of the carabelli trait in southwest ethnic groups. am j phys anthropol 17:117-123. kraus bs, jordan re. 1965. the human dentition before birth. philadelphia: lea and febiger. luukko k, loes s, furmanek t, fjeld k, kvinnsland ih, kettunen p. 2003. identification of a novel putative signaling center, the tertiary enamel knot in the postnatal mouse molar tooth. mech dev 120:270-276. macho ga, moggi-cecchi j. 1992. reduction of maxillary molars in homo sapiens sapiens: a different perspective. am j phys anthropol 87:151-160. macho ga, spears ir. 1999. effects of loading on the biomechanical [correction of biochemical] behavior of molars of homo, pan, and pongo. am j phys anthropol 109:211-227. mizoguchi y. 1988. degree of bilateral asymmetry of nonmetric tooth crown characters quantified by the tetrachoric correlation method. bull nat sci mus, tokyo, series d 14:29-49. moorrees cfa. 1957. the aleut dentition: a correlative study of dental characteristics in an eskimoid people. cambridge: harvard university press. moorrees cfa, fanning ea, hunt ee jr. 1963. age variation of formation stages for ten permanent teeth. j dent res 42:1490-1502. moss ml, applebaum e. 1962. differential growth analysis of vertebrate teeth. j dent res 36:644-651. olson ec, miller rl. 1958. morphological integration. chicago: university of chicago press. osborn hf. 1907. evolution of mammalian molar teeth to and from the triangular type. new york: macmillan. peretz b, nevis n, smith p. 1998. morphometric analysis of developing crowns of maxillary primary second molars and permanent first molars in humans. arch oral biol 43:525-533. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 68:157-164. rosenzweig ka. 1970. tooth form as a distinguishing trait between sexes and human populations. j dent res 49:1423-1426. salazar-ciudad i, jernvall j. 2002. a gene network model accounting for development and evolution of mammalian teeth. proc natl acad sci u s a 99:8116-8120. sharpe pt. 2001. neural crest and tooth morphogenesis. adv dent res ;15:4-7. swindler dr. 1976. dentition of living primates. new york: academic press. swindler dr. 2002. primate dentition: an introduction to the teeth of non-human primates. cambridge: cambridge university press. thesleff i, jernvall j. 1997. the enamel knot: a putative signaling center regulating tooth development. cold spring harb symp quant biol 62:257-267. thesleff i, keranen s, jernvall j. 2001. enamel knots as signaling centers linking tooth morphogenesis and odontoblast differentiation. adv dent res 15:14-18. townsend gc. 1985. intercuspal distances of maxillary pre-molar teeth in australian aboriginals. j dent res 64:443-446. townsend g, richards l, hughes t. 2003. molar intercuspal dimensions: genetic input to phenotypic variation. j dent res 82:350-355. turner cg ii, hawkey de. 1998. whose teeth are these? carabelli’s trait. in: lukacs jr, editor. human dental development, morphology, and pathology: a tribute to albert a. dahlberg. eugene: university of oregon anthropological papers, no 54, p 41-50. wolpoff mh. 1971. metric trends in hominid dental evolution. studies in anthropology, no. 2. cleveland: case western reserve university press. wood ba, abbott sa. 1983. analysis of the dental morphology of plio-pleistocene hominids. i. mandibular molars: crown area measurements and morphological traits. j anat 136 (pt 1):197-219. wood ba, abbott sa, graham sh. 1983. analysis of the dental morphology of plio-pleistocene hominids. ii. mandibular molars—study of cusp areas, fissure pattern and cross sectional shape of the crown. j anat 137 (pt 2):287-314. yamada h, brown t. 1988. contours of maxillary molars studied in australian aboriginals. am j phys anthropol 76:399-407. zeisz rc, nuckolls j. 1949. dental anatomy. st louis: cv mosby company. cusp areas of maxillary molars zubov 1992b.3 pg9.jpg pg10.jpg walker and shapiro 1992.3 pg9.jpg pg10.jpg pg11.jpg maier et al. 2017.5 39 dental anthropology 2017 │ volume 30 │ issue 01 in bioarchaeology, little attention has been paid to the indian subcontinent, especially compared to the volume of work on native americans and europeans. holocene foragers of north india: the bioarchaeology of mesolithic damdama contributes to the scholarship relating to the mesolithic lake culture (mlc) of northern india and helps expand the corpus of bioarchaeological work in india. lukacs and pal explore the life of the residents of damdama through a comprehensive analysis of human remains. the site of damdama, discovered in 1978, constitutes the third major mesolithic site in the region to yield a high number of artifacts in association with human remains. to an extent, the bioarchaeology of south asia has been limited by the poor preservation of human remains, resulting in a focus on the individual rather than the population. however, the damdama assemblage exhibits uncharacteristically good preservation, allowing lukacs and pal to address population-driven questions. additionally, the position of lukacs as an author makes this volume unique among studies of mesolithic lake culture peoples, as he studied the other two major mlc sites (sahar nahar rai and mahadaha). this volume involves comparisons among the three sites so potential interobserver biases are minimized. intersite comparisons allow for a discussion of the place of damdama among mlc peoples, and puts the indian mlc in a larger global context. this assemblage is comprised of 46 well-preserved individuals, allowing researchers to evaluate variables relating to diet, health, stress, activity levels, and the genetic characteristics of the residents of mesolithic damdama. to that end, chapters 9-11 focus on the wealth of information derived from the dentition. chapter 9 focuses on the dental inventory of the assemblage and provides information on the prevalence and degree of tooth wear. the dental inventory is an easily overlooked component of an analysis, but the authors emphasize that understanding sample composition is necessary to recognize potential limitations and biases of subsequent analyses. dental wear was scored using the quadrant system of e. scott (1979) and the eight grade system of langsjoen (1998). each system is discussed, highlighting its advantages and disadvantages, and noting the appropriate circumstances for implementation. ultimately, the combination of dental wear scores, and derived variables led the authors to conclude that the inhabitants of damdama, like other mlc peoples, consumed a coarse diet and were subject to heavy masticatory stresses. the pattern of dental wear in the damdama sample was additionally used to support the conclusion that this population subsisted using a hunting-foraging strategy. the authors present a unique use of the quadrant wear system (scott 1979) to assess the angle of molar wear as proposed by smith (1984). smith (1984) asserts that hunter-foragers tend to demonstrate a flatter molar wear plane, while agricultural populations show steeper planes of molar wear. to evaluate molar wear angle, lukacs and pal suggest wear scores of the lingual cusps can be compared to the buccal cusps – the greater the difference in wear scores, the more steeply angled the molar wear plane. the authors recognize this analysis may not be precise enough to capture subtle angle differences, but the combination of these two classic dental wear techniques is intriguing and represents an exciting new possibility for future dental anthropological studies. the focus of chapter 10, dental pathology, includes the prevalence of oral lesions and interpretations of their significance. the study of dental pathology is critical to any comprehensive bioarchaeological research project as it provides a snapshot of the diet and dietary behavior of past populations. in this chapter, the broad category of dental pathology includes developmental anomalies, infectious diseases, and degenerative conditions. we commend the authors on their explicit definitions of pathological conditions to ensure clarity to the reader and replicability in future research. dental pathology is explored in several contexts. first, frequencies of a given condition are presented by individual and by sex to discern patterns within these divisions. next, the rates of pathologic manifestations are compared between damdama and other hunter-forager and agriculturist groups to explore the effects of subsistence on pathology. after a discussion of the prevalence of enamel hypoplasia, the chapter concludes with an interpretation of the suite of conditions observed in the damdama sample. in total, the profile of the residents of damdama derived from an analysis of dental pathology is consistent with a hunterforager population with a diet of coarsely textured book review holocene foragers of north india: the bioarchaeology of mesolithic damdama. by john r. lukacs and jagannath pal, with contributions by m.c. gupta, v.d. misra, greg c. nelson, and g. robbins schlug. published in oxford by british archaeological reports ltd, 2016. pp. 328. isbn: 978-1-40731452-5, price £49.00, or a$63.15 40 dental anthropology 2017 │ volume 30 │ issue 01 food. rates of caries and periapical lesions are remarkably low, and rates of antemortem tooth loss are moderate on a world scale. enamel hypoplasias are common in this population, suggesting periods of childhood stress; however, post-cranial analyses of adult stature suggest these childhood stress episodes were not severe. the final chapter (11) focuses on the morphology and metrics of the damdama dentition. these data are used to explore the functional aspects of tooth size and morphology, as well as their utility in assessing population affinity. the sample available for the study of morphology was too small to be statistically robust; therefore, for discussions of morphology, the damdama individuals were grouped into a larger mesolithic lake culture group. the dental morphology of the mlc population is best described as simple. although incisor shoveling occurs with moderate frequency, few other mass-additive features were observed. biodistance analyses based on dental morphology align the collective mesolithic lake culture people with the generalized sundadont (turner 1990) and indodont (hawkey 1998) dental patterns. furthermore, these analyses reveal previously unidentified linkages between the peoples of the mlc and extant tribes. the analysis of tooth size is also revealing. the trend in tooth size at damdama is toward larger dentitions, exhibiting some of the largest teeth in all of south asia. the authors offer increased tooth size as support of a hunter-forager subsistence pattern in the mlc. taken together, the results of morphological and metric analyses of the damdama teeth are consistent with inferences of diet and subsistence derived from tooth wear and dental pathology. lukacs and pal are to be commended for their comprehensive examination of the bioarchaeology of the damdama site in northern india, particularly the thorough treatment of the dentition. this work represents the full-complement of a dental anthropologist’s contribution to the bioarchaeological literature. their focus on population-driven questions and quantitative methods represents the future of bioarchaeological research. the acknowledgment by these authors of potential biases and limitations throughout their research strengthens the final product. knowledge of potential problems helps the reader temper any conclusions drawn from this work. the authors set three goals for the volume: 1) to elucidate the utility of bioarchaeology in understanding prehistoric human behavior, 2) to explore the place of mesolithic hunter-foragers in the regional archaeological sequence, and 3) to approach the bioarchaeological data in an integrative and synthetic way in researching the mlc of north india. they achieve all three goals. this volume represents an exceptional standard for bioarchaeological work and shows how the dentition informs bioarchaeological questions and provides direction of future research in south asia. christopher a. maier1, ph.d.; kelly n. heim2, m.a.; and g. richard scott2 , ph.d. 1eckerd college 2 university of nevada, reno literature cited hawkey de. (1998). out of asia: dental evidence for affinities and microevolution of early populations from india/sri lanka. phd dissertation. arizona state university, tempe, az. langsjoen o. (1998). dental pathology. in: aufderheide ac and rodríguez-martin c, (eds). the cambridge encyclopedia of human paleopathology. cambridge, uk: cambridge university press, pp. 393-412. scott ec. (1979). dental wear scoring technique. american journal of physical anthropology, 51, 213218. smith bh. (1984). patterns of molar wear in huntergatherers and agriculturalists. american journal of physical anthropology, 63, 39-56. turner cg ii. (1990). major features of sundadonty and sinodonty, including suggestions about east -asian microevolution, population history, and late pleistocene relationships with australian aboriginals. american journal of physical anthropology, 82, 295-317. swindler 1992.6 pg13.jpg pg14.jpg hawkey 1991.3 pg9.jpg 90 dental anthropology 2019 │ volume 32 │ issue 02 dear friends and colleagues, it is with sadness that i write to inform you of the passing of professor grant townsend on may 25th, after battling illness over the last 12 months. many of you will know grant from his involvement in the dental anthropology association, and from his attendance at isdm and aapa meetings over the last 40 years. many of you will also have known him as a collaborator, co-author, supervisor, mentor and friend. it’s difficult to sum up the depth and breadth of grant’s contributions to the field of dental anthropology in a few short paragraphs, but some of his key achievements include holding the chair of dental science at the university of adelaide for over 20 years; work on the collection and analysis of a seminal longitudinal data set from the yuendumu people of central australia, with murray barrett and tas brown; initiating a series of longitudinal australian twin cohorts to quantify the role of genes and the environment in the development of various morphological features; publishing over 200 peer-reviewed articles, as well as numerous books and book chapters; and sitting on the editorial boards of many distinguished journals, including dental anthropology from 1997-2002. some of the many awards grant received during his career included the medaille de la ville de paris for contributions to research in the field of dental anthropology; the iadr(anz) alan docking science award for outstanding scientific achievement in the field of dental research, and the iadr distinguished scientist award for craniofacial biology research in recognition of outstanding contributions to research over a significant period of time. a great collaborator, grant spent time in many research centres internationally over the course of his career, including sabbaticals in finland and the united kingdom, and visits throughout south-east asia and the united states. during these times he developed long-standing friendships with other members of our community, many of whom would later go on to spend time in the murray barrett research laboratory in adelaide working on the collections grant curated. grant’s enthusiasm for dental anthropology never waned, and he continued to work on projects arising from the longitudinal cohorts up until early this year, many of which remain ongoing. grant will be missed by his extended research family at the craniofacial biology research group in adelaide, and by those he worked with around the world. toby hughes adelaide dental school faculty of health and medical sciences adelaide, south australia 5005 australia letter of obituary: grant townsend 26 dental anthropology 2014 │ volume 27 │ issues 01 and 02 aboriginal australians have been in their island setting for at least 40,000 years (crane 2013), but most change has occurred via immigration of europeans over the past two centuries (singh 2013). (australia was “discovered” in 1606 by the dutch vessel duyfken, captained by willem janszoon—though some claim an earlier european discovery). the social history of native australians unfortunately mirrors the deceit and abuse of american indians as the united states was peopled westward by europeans (prucha 1997). it is inspiring, then, that this nicely-written book, “the yuendumu: legacy of a longitudinal growth study in central australia” describes positive experiences for both aboriginals and academicians. this readable book is structured as a narrative history with chapters devoted to themes as diverse as tooth crown sizes (the well-known works of maury barrett 1963a,b on tooth crown sizes) to anthropometric dimensions of a cohort of aboriginal measured annually during the 1960s. it was written as a group effort but principally by tasman brown and grant townsend, both longtime participants with the yuendumu. the book is an homage to professor brown who devoted much of his professional career to the physical anthropological study of the yuendumu. a singular feature of this wonderfully-illustrated book is its ready availability. it can be purchased in the conventional paper format, but it can also be downloaded gratis as a pdf. the hard copy functions for highlighting and notation, but the electronic version is available everywhere, has the same colored plates, and can be annotated with any pdf reader. the book is presented from a historical vantage point, high-lighting the seminal dental and anthropological investigated spearheaded by dr. murray james barrett (1916-1975) of the university of adelaide, a student of thomas draper campbell (e.g., campbell 1925). yuendumu is a settlement northeast of alice springs in central australia. its attraction was a steady source of water that evolved into a sheep ranch and baptist mission with outreach to the aboriginals. today, the settlement consists of wooden houses, cars, and a native contingent of about 300. the book emphasizes that, from its inception, yuendumu was a government settlement and not a mission, with the responsibility for policy and daily affairs being that of the government. thus the missionaries were required to operate within the bounds of such policies as assimilation. however the baptists were involved in much more than meeting spiritual needs. they helped supply clothing and medical supplies, taught sewing, commenced and ran the first store, helped build and often staffed the hospital, commenced a kindergarten, and commenced the first school. early work at yuendumu involved barrett (and students and collaborators) making dental casts of the children and adults, though attrition and antemortem loss commonly affected the adults. this work was remarkable for the adelaide team’s repeated visits. the resulting mixed longitudinal nature of the study design is quite uncommon in the anthropological literature. the feat is the more remarkable because of the paucity (and, often, absence of) institutional funding for the teams. the semi-serial design was possible largely because of the aboriginals’ sedentism plus the trust and alliances between the researchers and the host population. group leaders even were given warlpiri names. murray barrett became a member of the jungarrayi group and tasman brown became a jakamarra. this rapport between the cultures—attributed mostly to barrett’s exuberant personality—formed the backbone for the years of study of this one aboriginal lineage. another fascinating feature of the “yuendumu study” was its multifaceted outlook. dental casts formed the base of the study, but many other data were collected, including kinship patterns, anthropometrics, lateral and posteroanterior head x-rays, genealogies, and more. while barrett’s classical studies of tooth size (1963a,b) are familiar to most dental anthropologists, other information is not— and it is all detailed in this book (including numerous useful references). book review legacy of a longitudinal growth study in central australia. by tasman brown, grant c townsend, sandra k pinkerton, james r rogers. published in adelaide by university of adelaide press, 2011. pp. 327. isbn: 978-0-9807230-9-0, price a$35.00, paperback. 978-0-9870730-0-6, free, e-book pdf. 27 dental anthropology 2014 │ volume 27 │ issues 01 and 02 the book offers much more, but it serves as a useful primer dealing with the logistics and organization of the ever-varying team from adelaide to yuendumu—originally a several-day safari some 285 km northwest from alice springs. over the course of the study, many renowned clinicians and scientists from abroad, including arne bjőrk, william proffit, and tsunehiko hanihara, accompanied the group, always extending the scope of studies with their particular interests. this history—well-documented in the text—also promotes the value of a multidisciplinary approach and how the components build synergistically on one another. bjőrk suggested the addition of cephalometric radiographs; proffit took telemetry recordings of the people’s masticatory patterns. the resulting breadth of the data collection forms a uniquely broad-ranging picture of an otherwise little-known non-european group. one of the other joys of the book is the careful and thorough list of references stemming from the decades of study. comprehensive lists are provided at the end of the chapters as well as an appendix. these collections of citations alone make the book invaluable. one message of the book is the irreplaceable value of a visionary and dedicated leader (murray barrett; tasman brown) coupled with a multidisciplinary approach—which are at the heart of anthropological studies—in combination with the merit of involving researchers with diverse but well-organized projects. funding for the yuendumu project was always meager, but the diversity of the studies permitted the broadest sources of funding, both in australia and internationally. this book is written by people deeply committed to the yuendumu project who described its history in detail. the yuendumu have continued to change, of course, including falling under the blight of unemployment. this book commemorates some of the positive histories of this group— a wonderful coming together of the aboriginals and researchers, and now documented for all time by a select group of dedicated researchers. edward f harris the health sciences university of tennessee, memphis 920 court avenue, memphis, tn 38163 references cited barrett mj, brown t, luke ji (1963a). dental observations on australian aborigines: mesiodistal crown diameters of deciduous teeth. aust dent j 8:299-302. barrett mj, brown t, macdonald mr (1963b) dental observations on australian aborigines: mesiodistal crown diameters of permanent teeth. aust dent j 8:150-155. campbell td (1925) dentition and palate of the australian aboriginal. adelaide: hassell press, 1925. cane s (2013) first footprints—the epic story of the first australians. sydney: allen & unwin. prucha fp (1997) american indian treaties: the history of a political anomaly. oakland, ca: university of california press. singh j (2013) history of australia–revisited. new delhi: prestige books. 23 dental anthropology 2020 │ volume 33 │ issue 01 a systematic literature review and case report of bilateral tworooted mandibular deciduous canines and their usefulness in forensic identification liliana marín 1 , sandra moreno 2 , and freddy moreno 2* 1 technical criminal investigative body at office of the attorney general, bogotá, colombia 2 faculty of health sciences of pontificia universidad javeriana cali, colombia there are two maxillary and two mandibular canine teeth located on each hemi-arcade among the incisors and premolars (kraus et al., 1969). the root of the maxillary canine is convex on its vestibular and lingual surface; its mesial and distal surfaces are broad and somewhat flattened; while the root of the mandibular canine is shorter and flatter with marked longitudinal grooves. the apical portions of the root could exhibit mesial drift, which may still have a bifurcation, making a double root (hillson, 1996). anatomically, the canines have a bulkier (in the vestibular-palatal or lingual) and longer root than the other teeth. this anatomy allows a strong anchor in the alveolar bone and gives a high resilience to forces generated in the masticatory cycle, depending on its high nociceptive capacity during the action of the muscles of mastication to sensory stimuli. this protection is achieved through the occlusal relationship between the maxillary and mandibular canines, in which, when the lateral movement of the mandible occurs the lower canines slide on the upper. this function is described in the literature as “canine function” or “canine key” to produce posterior teeth disclusion; hence, canines are seen as fundamental teeth of dental occlusion (scott & turner, 1998). these morpho-physiological traits and strategic position in the maxillaries give the canine teeth high resistance; for this reason, they are the teeth with the lowest prevalence of loss. therefore, canines have value in forensic odontological identification processes. in this context, dental anthropology through the characterization of individuals by analysis of expression and variation of root and coronal dental morphological traits is fundamental (rodríguez & delgado, 2000). in single-rooted teeth, as canines, the root sheath grows as a tube shape as radicular odontoblasts are differentiated. these odontoblasts regulate the process of dentinogenesis around the dental pulp, and are fragmented to allow the passage of cells that differentiate into cementoblasts from the dental follicle, which lead the process of cementogenesis. in multiradicular teeth, two or three primary apical foramen constitute the radicular trunk (according to the number of roots and their abstract a systematic review of the literature in pubmed was made by combining the terms “cuspid” and “tooth root” as mesh health descriptors, combined with the boolean operators “+” and “&” to obtain describing publications about two roots canines in order to sustain, on scientific evidence, the application of dental anthropology (dental morphological variations) in forensic science (forensic processes of dental identification). this literature review identified reports that describe the presence of two-rooted canines and the number and distribution of root canals for diagnostic and therapeutic purposes; and one report in which description was performed for forensic identification purposes. the descriptions corresponded to different cases of permanent maxillary canines with left unilateral expression, permanent mandibular canines with right unilateral expression, left unilateral expression with bilateral expression. there were no reports of deciduous dentition. likewise, a case report in which skeletonized human remains were identified by the presence of bilateral two-root mandibular deciduous canines is described. *correspondence to: freddy moreno faculty of health sciences pontificia universidad javeriana cali colombia fmorenog@javerianacali.edu.co keywords: forensic dentistry, dental identification, dental anthropology, deciduous tooth, canine teeth, two-roots 24 dental anthropology 2020 │ volume 33 │ issue 01 position). each root grows longitudinally as if it were a single-rooted tooth. therefore, the existence of a number of roots higher than normal is associated with hyperactivity of hertwig’s epithelial root sheath (hers) (holtzman, 1997) or its partial pathological degeneration, which causes an invagination by the dental papilla inducing an accessory root (sohn et al., 2014). this paper reports the case of skeletonized human remains that were identified using antemortem-postmortem dental comparison, due to the presence of a bilateral mandibular two-rooted deciduous canine. also presented is a review of the clinical literature on two-rooted canines. the goal of this paper is to demonstrate the application of dental anthropology (i.e., dental morphological variations) in the forensic dental identification processes. forensic odontology the process of identifying humans has particular relevance in human societies, because every single individual has an identity that must be conclusively proven at the time of death for social, cultural, religious, legal, and economic purposes. usually, the legal life begins with a birth certificate and ends with the death certificate (mertz, 1977). in the forensic sciences and during criminal investigations, investigators, prosecutors, and forensic experts (including the dentist) must interpret and classify the information collected. a careful examination of the soft and hard tissues of the stomatognathic system provides physical evidence that helps to establish the identity of a person (krishan et al., 1997). dental analyses and scrutiny of the soft and hard tissues that make up the stomatognathic system document physical evidence and/or injuries. if these are documented, it may help to establish the identity of an individual, to refute or confirm a testimony, or objectively link a victimizer with the victim and the crime scene; such as part of the comprehensive forensic analysis of a corpse and related elements within the context of each particular case (whittaker, 1995). teeth are used as an identification tool in forensic odontology investigations. their high identification value relies on the number of teeth, pathological conditions, restorations, dental materials used, prostheses, and implants. therefore, if a set of remains is missing teeth, it can be difficult to identify the individual (krishan et al, 1997; whittaker, 1995; rothwell, 2001; pretty & sweet, 2001a, 2001b). overall, dental identification is based on a comparison between the antemortem and postmortem record, which provides the forensic odontologist with enough distinctive features to make a positive identification (pretty & sweet, 2001a, 2001b). such characteristics are scientifically supported by the morphological individuality of the skeleton and teeth. this identification process can be comparative through analyses of antemortem dental records (medical history, dental chart, periodontal chart, radiographs, study models, cephalometric analysis, treatment plan, etc.) with postmortem and anthropological data. after performing the postmortem dental record of an unidentified individual or unknown set of human remains and having circumstantial evidence to suggest the possible identity of these, the next step is to obtain a dental medical history to collate postmortemantemortem dental records. which, according to the american board of forensic odontology (1994) and supported by national and international law, allows the establishment of a positive (total coincidence), possible (compatibility), insufficient (inadequate information available), or exclusive (incoherence and incompatibility) identification in a particular case. case history a male minor with a chronological age of 5 years was reported missing. the initial search to find this minor was unsuccessful. despite this, enquires in rural forensic units about cases of unidentified persons were made, finding out that in one of them, a set of unknown human skeletal remains was reported. the remains were found in a sugarcane plantation on the same date. the clothing worn by the individual on the day of his disappearance was found to be compatible with those on the skeletal remains. with this circumstantial evidence, the odontological medical history was obtained. this antemortem dental history did not contain radiographic images of the individual; however, the dentist noted in the chart the presence of deciduous lower two-rooted canines. a dental comparison was performed for the process of forensic identification. during which two reliable characteristics were discovered: the presence of deciduous lower two-rooted canines (figures 1 and 2), whose interradicular septum was evident in the alveolar process of the mandible (figure 3). in the postmortem radiographs of the deciduous canines it was possible to observe the presence of a root canal in every root and one pulp chamber in the crown of the tooth (figure 4). in the dental clinical setting, vertucci (2005) classified the number of roots and the number, shape, and configuration of the root ca25 dental anthropology 2020 │ volume 33 │ issue 01 nals for diagnostic and endodontic therapeutic purposes. in such a way, according to the configuration of the pulp chamber of the tooth and root canals, the case reported is classified as a type i, where each root has a single canal that ends in its own apical foramen. also, according to turner et al. (1991) the case was classified as a mandibular two-rooted canine. turner et al. (1991) standardized the observation of the number of roots of the mandibular canines, in which there are one or two roots, where the second one –usually a small, conical-shaped root directed towards lingual surface– is separated from the root trunk at the middle third. these features were sufficient to constitute reliable markers to positively identify the individual, despite the absence of radiographs. systematized search of the literature a systematic review of the literature in pubmed (a free-access search engine to medline database of the united states national library of medicine) was performed through the combination of health science descriptors: “cuspid” and “tooth root”, combined with the boolean operators: “+” and “&”, which were located in the medical subject headings (mesh). publications describing the presence of two-rooted canines were considered, in order to support the discussion of a case report of an individual with deciduous mandibular tworooted canines. results twenty-five publications fill the inclusion criteria, and were classified by year, type of tooth (deciduous or permanent, maxillary or mandibular canines), expression (unilateral or bilateral), sex (female or male), purpose of publication, and other important considerations (table 1). there was only one report in which a description was performed figure 1. deciduous lower two-rooted canines. buccal view. figure 2. deciduous lower two-rooted canines. lingual view. figure 3. in alveolar process of the deciduous lower two-roots canines of the mandible is evident the interradicular septum. figure 4. postmortem radiography of the deciduous lower two-rooted canines. 26 dental anthropology 2020 │ volume 33 │ issue 01 table 1. reports of two-rooted canines in the literature. u=upper, l=lower authors year permanent tooth expression gender number of roots/ canals objective considerations rahmatulla & wyne 1993 lc unilateral (right) female two roots / two canals case report the description of the distribution in roots canals is performed heling et al. 1995 lc no reporting no reporting two roots / three canals case report according to the authors this is the first time a mandibular canine three canals ouellet 1995 lc no reporting no reporting two roots / two canals descriptive study 806 canines were examined 95% of which has a root and 5% two roots orguneser & kartal 1998 lc no reporting no reporting two roots / three canals(two apical foramen) case report the description of the distribution in roots canals is performed d´arcangelo et al. 2001 lc unilateral (right) female two roots / two canals case report the description of root canal treatment is performed in decayed tooth alapati et al. 2006 uc unilateral (right) male one root / two canals case report the description of root canal treatment is performed in decayed tooth bolla & kavuri 2009 uc unilateral (left) female two roots / two canals case report the description of root canal treatment is performed in decayed tooth wang et al. 2009 lc unilateral (right) female two roots / two canals case report the description of the distribution in root canals and the root canal treatment in victorino et al. 2009 lc bilateral female two roots / two canals case report the presentation of a case of bilateral mandibular canines with two canals and oporto et al. 2010 lc unilateral (left) female two roots / two canals case report the description of root canal treatment is performed in decayed tooth andrei et al. 2010 lc unilateral (right) female two roots / two canals case report the description of the distribution in root canals is performed andrei et al. 2011 lc unilateral (right) female two roots / two canals case report the description of the conventional root canal treatment and apical surgery fonseca et al. 2011 lc unilateral (left) male two canals case report the description of root canals treatment of bifurcation lesion and vertical loss of bolla & kavuri 2011 uc unilateral (left) female one root / two canals case report the description of root canals treatment is performed in decayed tooth gaikwad 2011 lc unilateral (left) female two roots / two canals case report the description of root canals treatment is performed in decayed tooth bhardwaj & bhardwaj 2011 lc unilateral (right) female two roots / two canals case report the description of root canals treatment by recurrent tooth decay due to restoramoogi et al. 2012 lc unilateral (right) female two roots / two canals case report the description of root canals treatment is performed ferreira et al. 2012 lc unilateral (right) no reporting two roots / two canals case report morphological description of the tooth roots for forensic identification is perkaul et al. 2012 lc unilateral (left) female two roots / two canals case report morphological description of the dilaceration of the two roots and their respective root canals treatment is performed he et al. 2013 lc bilateral male one root / multiples canals letter to the editor presentation of a case of bilateral mandibular canines with multiple canals, root canals treatment and restoration of anterior teeth is performed ramírezsotelo et al. 2013 lc unilateral (right) female two roots / two canals case report morphological description of roots using computed tomography was performed fuentes & borie 2013 lc bilateral female two roots / two canals case report morphological description of roots using conventional radiography was performed chawla et al. 2013 uc unilateral (left) female one root / two canals case report the description of root canals treatment in decayed tooth is performed mithunjith.& borthakur 2013 lc unilateral (left) female two roots / two canals case report the description of root canals treatment in decayed tooth is performed arora, nikhil & gupta 2013 lc unilateral (left) female one root / two canals case report the description of root canals treatment in decayed tooth is performed 27 dental anthropology 2020 │ volume 33 │ issue 01 for forensic identification purposes; the primary means of description were conventional radiography and computed tomography. the descriptions corresponded to four cases of permanent maxillary canines with left unilateral expression; the other 21 cases were permanent mandibular canines, with right unilateral expression (10 cases); left unilateral expression (9 cases) and bilateral expression (3 cases). nineteen cases in female and three in male subjects were reported; two-root expression, each root with a canal, was predominant (18 cases). there were no reports in deciduous dentition. discussion usually, the maxillary and mandibular canines are considered as a single-rooted tooth, given the high prevalence of 93.48% of this condition (oporto et al., 2010), however, brothwell –cited by ferreira et al. (2012)– collected several reports on the prevalence of two-rooted canine expression, finding no population significant differences related to ethnic pattern, bilateral expression, or sexual dimorphism. according to the literature, the morphological variation related to the number of roots is 1% to 2% for the maxillary canines, and 1.3% to 15% for the mandibular canines, mainly the two roots and two canals expression with one canal per root (bolla & kavuri, 2011). exceptionally, mandibular two-rooted canines and three canals have been reported (heling et al., 1995), as well as, two-rooted canines, three canals, and two apical foramina (orguneser & kartal, 1998), single-rooted canines and two canals (arora, 2013), and single-rooted canines with multiple canals (he et al., 2014). another important feature is that in most cases of canines with two roots these are distributed in a buccal and lingual direction (ferreira et al, 2012); however, in this case report, the roots were distributed in a mesial and distal direction. thus, most of the reports suggest that canines with two roots correspond to a shape abnormality of the tooth during morphogenesis, related to an alteration of the hers. a tooth root develops from the hers and around the dental papilla underneath the dental follicle, until it completely cover the papilla in the primary apical foramen (thomas, 1995). the systematic review of the literature predominantly described canines with more than one root to demonstrate the clinical difficulty of root canal treatment of these teeth after the development of pathological processes (usually caries). this difficulty is mainly related to the identification of the longitudinal course of the canals due to superimposed radiographic images, the narrowness of the canals, complications from filling them, and apical sealing (bolla & kavuri, 2009). radiographic images were used for forensic purposes, in order to identify features that allow the identification of the decedent from the shape, size, and number of roots of the teeth (senn & weems, 2013). thus, ferreira et al. (2012) reported a case of a mandibular tworooted canine with two canals in a decomposing set of remains. however, although the victim was not identified by the dental setting, the authors state that given the low prevalence of this dental trait, could eventually become a valuable tool for forensic odontology identification. conclusions in this case report, it is evident that the study of dental morphological variation from the point of view of dental anthropology –as in the case of bilateral expression of mandibular two-rooted canines– constitutes a reliable marker that allows a positive identification of an individual during antemortem-postmortem comparisons in the field of forensic odontology. in the literature, the expression of bilateral lower two-rooted canines was found to be rare. in this case, the observation and recording of the presence of a bilateral temporal expression of lower two-rooted canines contributed to the process of dental forensic identification, specifically the information registered by the dentist in the dental chart. the medical history had no radiographic records. references alapati, s., zaatar, e. i., shyama, m. & al-zuhair, n. (2006). maxillary canine with two root canals. medical principles and practice, 15(74), 6. american board of forensic odontology abfo (1994). body identification guidelines. the journal of the american dental association, 125(9), 1244-54. andrei, o. c., mărgărit, r. & dăguci, l. (2010). treatment of a mandibular canine abutment with two canals. romanian journal of morphology and embryology, 51(3), 565-8. andrei, o. c., mărgărit, r. & gheorghiu, i.m. (2011). endodontic treatment of a mandibular canine with two roots. romanian journal of morphology and embryology, 52(3), 923-6. arora, v., nikhil, v. & gupta, j. (2013). mandibular canine with two root canals: an unusual case report. international journal of stomatological research, 2(1), 1-4. bhardwaj, a. & bhardwaj, a. (2011). mandibular canines with two roots and two canals: a case report. international journal of dental clinics, 3(3), 28 dental anthropology 2020 │ volume 33 │ issue 01 77-8. bolla, n. & kavuri, s. r. (2009). a case of unusual root morphology: maxillary canine with two roots. journal of international clinical dental research organisation, 1(3), 70-5. bolla, n. & kavuri, s. r. (2011). maxillary canine with two root canals. journal of conservative dentistry, 14(1), 80-2. chawla, a., sujlana, a. & chawla, h. s. (2013). endodontic management of maxillary canine with two root canals. indian journal of dentistry, 5 (suppl.), 112-5. d’arcangelo, c., varvara, g. & de fazio, p. (2001). root canal treatment in mandibular canines with two roots: a report of two cases. international endodontic journal, 34(4), 331-4. ferreira, r., machado, m., de lucena, t., vieira, r. & de acevedo, d. e. (2012). anatomical variations in the permanent mandibular canine: forensic importance. revista sul-brasileira de odontologia, 9(4), 468-73. fonseca, d. r., sena, l. g., santos, m. h. & goncalves, p. f. (2011). furcation lesion in a mandibular canine. general dentistry, 59(4), 173-7. fuentes, r. & borie, e. (2013). bilateral two-rooted mandibular canines in the same individual: a case report. international journal of odontostomatology, 7(3), 471-3. gaikwad, a. (2001). endodontic treatment of mandibular canine with two canals: a case report. international journal of dental clinics, 3(1), 118-9. he, l. b., shao, m. y., xu, x. & li, j. y. (2014). bilateral mandibular canines with single root and multiple canals. journal of dental sciences, 9(2), 199-201. heling, i., gottlieb-dadon, i. & chandler, n. p. (1995). mandibular canine with two roots and three root canals. dental traumatology, 11(6), 301 -2 hillson, s. (1996). dental anthropology. london: cambridge university press. holtzman, l. (1997). root canal treatment of a mandibular canine with three root canals. case report. international endodontic journal, 30, 291-3. kaul, r., farooq, r., purra, a. r., bhagat, r. k. & khateeb, s. u. (2012). two rooted mandibular canine with severe dilacerations. international journal of clinical cases and investigations, 4(1), 759. kraus, b. s., jordan, r. e. & abrams, l. (1969). dental anatomy and occlusion. st. louis: lippincott williams & wilkins. krishan, k., vashisht, r. n. & vij, k. (1997). teeth in personal identification. medico-legal update, 2 (1-2), 9-11. mertz, c. a. (1977). dental identification. dental clinics of north america, 21(1), 47-67. mithunjith, k. & borthakur, b. j. (2013). endodontic management of two rooted mandibular canine. e-journal of dentistry, 3(1), 339-42. moogi, p. p., hegde, r. s., prashanth, b. r. et al. (2012). endodontic treatment of mandibular canine with two roots and two canals. journal of contemporary dental practice, 13(6), 902-4. oporto, v. g. h., fuentes, f. r. e. & soto, p. c. c. (2010). variaciones anatómicas radiculares y sistemas de canales. international journal of morphology, 28(3), 945-50. orguneser, a. & kartal, n. (1998). three canals and two foramina in a mandibular canine. journal of endodontics, 24(6), 444-5. ouellet, r. (1995). mandibular permanent cuspids with two roots. journal of the canadian dental association, 61(2), 159-61. pretty, i. a. & sweet, d. (2001). a look at forensic dentistry part 1: the role of teeth in the determination of human identity. british dental journal, 109(7), 359-66. pretty, i. a. & sweet, d. (2001). a look at forensic dentistry part 2: teeth as weapons of violence identification of bitemark perpetrators. british dental journal, 190(8), 415-8. rahmatulla, m. & wyne, a. h. (1993). bifid roots in a mandibular canine: report of an unusual case. the saudi dental journal, 5(2), 77-8. ramírez-sotelo, l. r., sampaio, f., roque-torres, g. d., queiroz de freitas, d., de almeida, s. m. & bóscolo, f. n. (2013). canino mandibular con dos raíces. revista cubana estomatología, 50(2), 211-8. rothwell, b. r. (2001). principles of dental identification. dental clinics of north america, 2001, 45 (2), 253-70. senn, d. r. & weems, r. a. (2013). manual of forensic odontology. florida: crc press. sohn, w. j., choi, m. a., yamamoto, h. et al. (2014). contribution of mesenchymal proliferation in tooth root morphogenesis. journal of dental research, 93(1), 78-83. thomas, h. f. (1995). root formation. international journal of developmental biology, 39, 2317. turner ii, c. g., nichol, c. r. & scott, g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in kelly m.a. & larsen c.s .(eds.), advances in dental anthropology (pp. 13-31). new york: wiley-liss. vertucci, f. j. (2005). root canal morphology and 29 dental anthropology 2020 │ volume 33 │ issue 01 its relationship to endodontic procedures. endodontic topics, 10, 3-29. victorino, f. r., bernardes, r. a., baldi, j. v. et al. (2009). bilateral mandibular canines with two roots and two separate canals case report. brazilian dental journal, 20(1), 84-6, 2009. wang, l., zhang, r. & peng, b. (2009). clinical features and treatment of mandibular canines with two root canals: two case reports. chinese journal of dental research, 12(1), 61-2. whittaker, d. k. (1995). forensic dentistry in the identification of victims and assailants. journal of clinical forensic medicine, 2, 145-51. williams et al. 2017.1 3 dental anthropology 2017 │ volume 30 │ issue 01 expression of nonmetric dental traits in western european neanderthals frank l’engle williams 1,* , rebecca l. george 2 , marie-antoinette de lumley 3,4 , gaël becam 3,* 1 department of anthropology, georgia state university, atlanta, ga 30303 2 department of anthropology, university of nevada, reno, nv 89557 3 umr 7194 cnrs, hnhp, mnhn/upvd/cerp de tautavel, france neanderthals are known for their taurodont molar roots, shovel-shaped incisors as well as the expression of dental morphological features that are relatively uncommon in modern humans (patte, 1959; zubov, 1992; bailey, 2000, 2002, 2004, 2006; hublin et al., 2012). however, differences may also exist between neanderthal sites, irrespective of their relationship to modern humans. small family groups and a relatively limited degree of genetic variation may have characterized neanderthals (lalueza-fox et al., 2011; kelso and prüfer, 2014). using observations of dental morphology from a relatively large sample of neanderthals (n = 12) from western europe, we examine whether ecogeography or chronology (or neither) more adequately accounts for the variation observed. six individuals from a single site (hortus) allow for a comparison of within and between fossil assemblages to investigate the expression of nonmetric dental traits. we also note which features are commonly expressed or are unusual in this sample of neanderthals. neanderthals of western europe several regions of western europe appear to have been core areas of neanderthal habitation, even when colder conditions prevailed (hublin and roebroeks, 2009). neanderthal tools, faunal remains, and osteological remnants in these regions are situated primarily between marine isotope stages (mis) 5 to 3 (soressi et al., 2007), and are evidenced as far north as belgium to the terminus of mis 3 (würm ii) at about 36 kya as demonstrated by the remains from spy cave (semal et al., 2005, 2009; toussaint et al., 2011; pirson et al., 2014). the earliest neanderthal discovered in 18291830, engis 2, is probably also from mis 3 based on associated mousterian artifacts and fauna (twiesselmann, 1971), although it could be younger, between 26,830 ± 430 and 30,460 ± 210 years bp (toussaint et al., 2011). scladina 1-4a, also located along the meuse river basin of belgium, has been dated to mis 5 or earlier (pirson et al., 2014), attestabstract neanderthals of western europe lived across distinct ecogeographic zones from marine isotope stage 7 to 3. differences in dental morphology from seven western european sites are compared in terms of ecogeography and chronology. neanderthals (n = 12) along a north-south gradient were examined. these included the meuse river basin of belgium (engis 2 and scladina 1-4a ), southwest france (pech de l'azé 1 and roc de marsal), the pyrenees (malarnaud and montmaurin), and the mediterranean (hortus). montmaurin is the oldest, followed by scladina 1-4a and malarnaud, whereas the others are younger. dental casts were prepared from neanderthal permanent and deciduous dentition. these were described and scored, according to the asudas. comparisons of dental traits with respect to ecogeographic regions and chronological categories were constructed. unusual dental features observed include the anterior fovea, entoconulid, metaconulid, and carabelli’s cusp. dental traits that distinguish ecogeographic regions are the expression of the m1 hypocone and metaconule, whereas the hypoconulid and carabelli’s cusp separate chronological categories. differences are present for the entoconulid and metaconulid in both comparisons. neither chronology nor ecogeography fully explains the results. similarities in dental traits exist between roc de marsal, pech de l’azé 1 and engis 2, and secondarily within the hortus assemblage. *correspondence to: dr. frank l’engle williams, department of anthropology, georgia state university e-mail: frankwilliams@gsu.edu dr. gaël becam, umr 7194 cnrs, hnhp, mnhn/ upvd/cerp de tautavel, france gael.becam@cerptautavel.com keywords: engis 2, hortus, malarnaud, montmaurin, pech de l’azé 1, roc de marsal , scladina 1-4a 4 dental anthropology 2017 │ volume 30 │ issue 01 ing to the probable recolonization of the meuse river basin of belgium after the climate deterioration of mis 4 (hublin and roebroeks, 2009; toussaint et al., 2011; di modica et al., 2016). scladina 1-4a is probably between 80 -87 kya based on chronostratigraphic analyses using the greenland record as context, although it could be as old as 127 kya (pirson et al., 2014; toussaint et al., 2014). additional neanderthal sites in western europe include those from the perigord such as roc de marsal, which has been dated to 60-70 kya and is close to the terminus of mis 4 (guérin et al., 2012), and pech de l’azé 1 and has been dated to 51-41 kya (soressi et al., 2007). further south along the slopes of the northern pyrenees in the ariégeoises region is the site of malarnaud, which is suggested to be from the riss-würm interval (mis 5). also from the northern pyrenees region is montmaurin cave which has been dated to mis 7 (crégut-bonnoure et al., 2010). the mediterranean region may have been at least partially isolated from the pyrenees and other areas by glacier formations in the massif central and in particular, the languedoc mountains. between the mediterranean coast and the piedmont region south of this glaciation is the cave of hortus yielding between 20 and 36 neanderthal children and adults, and dated to mis 3 (würm ii) (lumley, 1973, 1976). six of the hortus remains are examined here, including hortus ii, hortus iv, hortus v, hortus vi, hortus viii, and hortus xi. dental traits in these disparate ecogeographic zones may vary as a function of distance. alternatively, individuals may differ with respect to time period, whereby older sites (montmaurin, scladina 1-4a and malarnaud) may be distinct from the younger sites of engis 2, hortus, pech de l’azé 1 and roc de marsal. the explanatory power of these models is explored here with respect to the dental morphology of western european neanderthals. materials and methods a total of 12 neanderthals from seven sites are sampled in this study. two individuals are represented solely by deciduous molars, two preserve both deciduous and permanent teeth and seven include only the permanent molars. table 1 lists the teeth examined by site and individual. a macroscopic investigation of the original fossil dentition was conducted by the first author (flw) at the musée de l'homme, the centre européen de recherches préhistoriques de tautavel, the musée national de préhistoire, les eyzies-de-tayac, the université de liège, and the scladina cave archaeological centre. the fossil teeth and scladina resin casts were molded using polyvinylsiloxane (coltène-whaledent). dental casts were created from the dental molds using centrifuged epoxy resin and hardener (buehler) at the bioarchaeology lab of georgia state university, and were examined by one observer (rlg) using the arizona state university dental anthropology system (asudas; turner et al., 1991) and a nonmetric data scoring sheet developed by r.l. george. the dental scoring system of the asudas is a replicable method in which the teeth are scored at different intervals to account for the expression of a feature. deciduous anterior teeth were scored according to the hanihara (1961) standards for deciduous dentition. the macroscopic observations of the original neanderthal fossil dentition were included where necessary. however, only traits visible on the dental casts were scored and recorded using fossil teeth examined ecogeography chronology engis 2 di1, dc, dm1, dm2, dm1, dm2, m1 meuse river basin (belgium) younger hortus ii m1 mediterranean (france) younger hortus iv m1, m2 mediterranean (france) younger hortus v m1, m2, m3 mediterranean (france) younger hortus vi m3 mediterranean (france) younger hortus viii m1 mediterranean (france) younger hortus xi m3 mediterranean (france) younger malarnaud m1 pyrenees (france) older montmaurin m1, m2, m3 pyrenees (france) older pech de l'azé dm1, dm2, dm1, dm2 southwest france younger roc de marsal dm1, dm2, dm1, dm2 southwest france younger scladina 4a dm1, dm2, m2, m1, m2 meuse river basin (belgium) older table 1. neanderthal dentition used in morphology descriptions. 5 dental anthropology 2017 │ volume 30 │ issue 01 the asudas. results engis 2 engis 2 preserves a relatively complete immature calvarium, isolated maxilla and several teeth, and has been aged to between four and five years (tillier, 1983; minughpurvis, 1988; toussaint et al., 2011; williams, 2013; williams and cofran, 2016). the dental remains of engis 2 examined here include the left maxillary deciduous incisors (di1 and di2), which are shoveled (hanihara grade 3), and a right maxillary deciduous canine characterized by a weakly developed tuberculum dentale (hanihara grade 5). the right maxillary deciduous molars (dm1 and dm2) are described as well as the right mandibular deciduous first molar (dm1) and right permanent first molar (m1). the right maxillary deciduous first molar (dm1) exhibits small wear facets on the cusp tips, although much of the original morphology is preserved. there are a total of five cusps and the metacone can be described as only weakly developed (asudas grade 3). similarly, the hypocone is also small (asudas grade 3) on dm1. the right maxillary deciduous molar (dm2) has a lack of substantial attrition. on dm2 there are four cusps, and the metacone and hypocone are visibly larger than on dm1 (asudas grade 4). a small, but noticeable carabelli’s trait can be observed on the second deciduous molar (dm2). however, it is not an independent cusp and its distal border does not contact the lingual groove between the protocone and the hypocone (asudas grade 5). the right mandibular deciduous second molar (dm2) exhibits a well-developed anterior fovea which is bordered by a pronounced mesial margin (asudas grade 4). the deciduous second molar (dm2) has five cusps inclusive of a prominent hypoconulid (asudas grade 5). furthermore, a rather large metaconulid can also be observed within the lingual groove between the metaconid and entoconid (asudas grade 4) on dm2. two large roots are present. the lower right first permanent molar (m1) was probably unerupted or in the process of eruption given the absence of substantial root development (1-2 mm in length) and the virtual lack of attrition with the possible exception of a tiny wear facet on the metaconid. the right permanent first molar (m1) of engis 2 has six cusps with a weakly developed hypoconulid (asudas grade 1). lingual to the hypoconulid, a small entoconulid, or sextum tuberculum, is represented as a second lingual groove (asudas grade 1). furthermore, a small, but noticeable metaconulid exists within the lingual groove between the metaconid and the entoconid (asudas grade 2). the groove pattern on the permanent first molar (m1) can be described as conforming to the “y” pattern. a weakly developed protostylid can be observed as a small pit on the buccal surface of the protoconid (asudas grade 1). hortus ii hortus ii, shown in figure 1, is represented by right and left mandibular permanent first molars and has been aged to 7-8 years (lumley, 1973). hortus ii is the accompanying lower jaw of the maxilla identified as hortus iii (lumley, 1973; minugh-purvis, 1988). there is only minimal to moderate wear on the permanent first molars (m1). the left first molar (m1) of hortus ii (1262) preserves an anterior fovea (asudas grade 3) (lumley, 1973). the protoconid is large, pointed and separated from the hypoconid by a large buccal groove. a large, but short distobuccal groove separates the hypoconid and hypoconulid (lumley 1973). similarly, the lingual cusps are separated by a large lingual groove. the groove pattern of the first molar (m1) can be characterized as exhibiting a “y” form. the medial ridge of the metaconid is deflected distally, although it does not approach the entoconid in size (asudas grade 2). a small, welldeveloped metaconulid is evident (asudas grade 2) (see fig. 1). hortus iv hortus iv consists of a mandibular corpus and the inferior ascending ramus of a young adult aged 18-25 years (lumley, 1973). hortus iv preserves the left permanent first and second molars (m1 and m2) and the right permanent second incisor (i2), canine (c) and first and second molars (m1 and m2) in situ. the corpus is badly damaged, but the teeth are well preserved and only minimally worn. heavier wear facets exist along the buccal occlusal surface figure 1. on the right mandibular permanent first molar (m1) of hortus ii, a number of dental features can be observed, such as a metaconulid (a) and an anterior fovea (b). 6 dental anthropology 2017 │ volume 30 │ issue 01 of both molar rows in contrast to the lingual surfaces (lumley, 1973). an anterior fovea exists on all the molars (fig. 2; lumley, 1973). on the right permanent first molar, the anterior fovea is represented as a large and elongated groove distal to a pronounced mesial ridge (asudas grade 4) (see fig. 2). the same could be said for the left permanent second molar (m2). however, the right permanent second molar (m2) exhibits a slightly less elongated anterior fovea than its antimere (asudas grade 3). the groove pattern of the right permanent second molar (m2) evidences an “x” classification. on the second molars (m2), a total of six cusps can be observed and a mid-trigonid crest connects the distal borders of the protoconid and metaconid (asudas grade 1). the buccal surface of the protoconid of the right second molar (m2) exhibits a small protostylid (asudas grade 1). a prominent hypoconulid can be found on the molars (asudas grade 4), although on the right second molar (m2) it is smaller (asudas grade 3). an entoconulid can be observed lingual to the hypoconulid on the second molars (m2); on the right side, the two cuspules are similar in size (asudas grade 3) (see fig. 2). on the left second molar (m2), the entoconulid is somewhat smaller than the hypoconulid (asudas grade 1). a small metaconulid is evident within the lingual groove between the metaconid and the entoconid on the first and second molars (m1 and m2) (asudas grade 2). hortus v there are several isolated teeth associated with hortus v, and the age has been estimated to be 18-25 years (lumley, 1973). the left (730) and right (988) permanent first molars (m1) exhibit moderate wear, heavier on the buccal than on the lingual cusps (lumley, 1973) and dentine exposures can be observed. on the right (988), the metaconid is rather large and pyramidal. the hypoconulid is positioned buccally and distally. five cusps are visible on the left (730) first molar (m1) and a small protostylid is evident within the buccal groove separating the protoconid and the hypoconid (asudas grade 1). a welldeveloped hypoconulid is visible on the first molars (m1), although it is larger on the right (asudas figure 2. the left (a) and right (b) mandibular permanent first and second molars (m1 and m2) of hortus iv exhibit well-demarcated anterior foveae. variation in the development of the entoconulid (cusp 6) is evident such that it is comparatively smaller vis-à-vis the hypoconulid on the left (c) compared to the relative size of the entoconulid on the right (d) permanent second molars (m2). 7 dental anthropology 2017 │ volume 30 │ issue 01 grade 3) than on the left (asudas grade 2). the left (693) second molar (m2) exhibits less attrition than the first molars (m1). taurodont roots are present and the mesial ones are joined together as are the distal ones (lumley, 1973). a small metaconulid is nestled within the lingual groove between the metaconid and the entoconid (asudas grade 2), which is unusual on a permanent second molar (turner et al., 1991). the right (796) and left (695) third molars (m3) present a well preserved and complex morphology. a prominent anterior fovea can be observed on the right (796) third molar (m3), and it is positioned rather mesially (asudas grade 4). a slightly smaller anterior fovea is evident on the left (695) third molar (m3) (asudas grade 3). the right (796) third molar (m3) preserves a groove pattern whereby a “+” classification is evident. there are six cusps on both third molars (m3) and a mid-trigonid crest can be observed (asudas grade 1) on the right (796) third molar (m3). a hypoconulid exists on both third molars (m3), and on the left (695) it is bifurcated and much larger (asudas grade 5) than on the right (796) (asudas grade 3). both third molars exhibit an entoconulid, albeit the expression varies, such that the left (695) expression (asudas grade 2) is more pronounced than the right (796) (asudas grade 1). both third molars (m3) also exhibit a pronounced metaconulid (asudas grade 2) which is rare for this dental element (turner et al., 1991). hortus vi hortus vi is represented by a left mandibular third molar (m3) from a young adult estimated to be 22-30 years (lumley, 1973). much of the original morphology is preserved (lumley, 1973). an anterior fovea is present and well-defined (asudas grade 3) (lumley, 1973). a complex morphology characterizes the occlusal surface, and there are a total of six cusps, the first four of which are in close proximity to one another corresponding to the “+” classification. a weak protostylid is represented as a small fovea within the buccal groove between the protoconid and hypoconid (asudas grade 1), although it is closer to the superior buccal surface of the hypoconid. a moderately sized hypoconulid is evident (asudas grade 3) as is an entoconulid, represented as a small fovea on the distal edge of the occlusal surface (asudas grade 3). the hypoconulid and entoconulid are similarly-sized. hortus viii hortus viii is a well-preserved right maxillary permanent first molar (m1) which has been aged to 2634 years (lumley, 1973). the tooth is somewhat triangular. a prominent metacone exists (asudas grade 5) that rivals the size of the stronglypronounced hypocone (asudas grade 5), and a large distal groove separates the two. hortus xi the right maxillary permanent third molar (m3) of hortus xi has been aged to 45-50 years (lumley, 1973). the tooth is rectangular in shape. striations on the occlusal, buccal, and mesial surfaces may possibly derive from paramasticatory behavior (lumley, 1973). much of the surface morphology has been destroyed and dentine exposures are evident on the mesial cusps. the metacone is rather small in comparison (asudas grade 3). a weakly developed parastyle is evidenced as a fovea lodged within the buccal groove between the paracone and metacone (asudas grade 1). malarnaud malarnaud preserves a right permanent first molar (m1) in situ and crypts for all other permanent teeth are visible, with the exception of the left third molar crown (m3); the right third molar (m3) crown can be partially observed deeply embedded within its crypt, and thus far from eruption. malarnaud has been aged to around 14 years (petite-marie et al., 1971), but may be younger given the minimal wear on the right first permanent molar (m1). a welldeveloped anterior fovea is present (asudas grade 3). a mid-trigonid crest is evident between the protoconid and the metaconid (asudas grade 1). the cusp number is five. a deflecting wrinkle is present (asudas grade 1). a buccal groove between the protoconid and metaconid can be observed (asudas grade 4), although the feature does not approach the development of a protostylid with a free apex. montmaurin this young adult is represented by a nearly complete mandibular corpus and has right and left permanent molars rows (m1-m3) in pristine condition, in situ, with minimal wear. the wear facets are most pronounced on the left first molar (m1) buccal cusps, followed by those on the right antimere. the anterior dentition and premolars are represented by crypts. a clearly demarcated anterior fovea is evident on all three molars, although on the first and second molars (m1 and m2) it is larger (asudas grade 2), in comparison to the third molar (m3) (asudas grade 1) (fig. 3). the anterior fovea is accentuated further by a strongly developed midtrigonid crest (asudas grade 1) on the right and left first and second molars (m1 and m2), and on the left third molar (m3). the morphology of all the mo8 dental anthropology 2017 │ volume 30 │ issue 01 lars is complex, particularly the third molars (m3), which can be described as crenulated. on the right first molar (m1), the groove pattern corresponds to the “y” configuration. on the left second molar (m2), a “+” classification is evident, whereas on the right antimere, only the protoconid and entoconid are in contact indicative of the “x” groove pattern. there are five cusps on the first and second molars (m2 and m2) and the left third molar (m3), and four cusps on the right third molar (m3). a pit can be observed on the buccal surface of the protoconid of the right first molar (m1) (asudas grade 1), and is expressed as a more pronounced groove that curves distally on the buccal surface of the protoconid of the right second molar (m2) (asudas grade 2), though, neither can be described as a true protostylid. the hypoconulid can be characterized as large (asudas grade 5), at least on the left first molar (m1), and, though it is present on the left second and third molars (m2 and m3), it is much smaller (asudas grade 1). the molars on the right each exhibit a smaller hypoconulid compared to their counterparts on the left. pech de l’azé i the remains of pech de l’azé i include a nearly complete cranium and mandible of a young child that has been aged to between 2.5 and 3 years (heim, 1976; minugh-purvis, 1988; williams, 2013; williams and cofran, 2016). all of the deciduous teeth are fully erupted, although, the maxillary lateral incisors are missing postmortem. dental attrition is minimal such that the deciduous molars preserve much of the original occlusal morphology. both of the maxillary deciduous first molars (dm1) exhibit four cusps (asudas grade 4). the right and left deciduous first molars (dm1) exhibit a relatively small metacone, although, a free apex is present (asudas grade 3). the hypocone is weakly developed and is represented as a small ridge on the distobuccal aspect of the deciduous first molars (dm1) on both sides (asudas grade 1). on the deciduous second molars (dm2), five cusps are present. in comparison to the deciduous first molars (dm1), the metacone is quite large on the second molars (dm2) (asudas grade 4). the hypocone is much larger on the deciduous second molars (dm2) compared to those expressed on the first molars (dm1). however, the left deciduous second molar (dm2) expresses a large hypocone (asudas grade 4), while on the right antimere it is slightly smaller (asudas grade 3). a prominent carabelli’s trait is present on the deciduous second molars (dm2) as an independent cusp with a free apex (asudas grade 7) (fig. 4). a weak metaconule is present within the distal groove separating the hypocone and metacone on both deciduous second molars (dm2), although it is somewhat larger on the left (asudas grade 2) than on the right (asudas grade 1). the mandible of pech de l’azé 1 is remarkably complete, although only on the right side are the teeth well preserved. the deciduous teeth are fully erupted with minimal attrition. the permanent first molar crown (m1) can be observed deeply in its crypt and the interior occlusal surface of the crown is complex. on the right deciduous first molar (dm1) of pech de l’azé 1, an elongated and pronounced anterior fovea is evident, bordered by a prominent mesial ridge (asudas grade 4). four cusps can be observed on the right deciduous first molar (dm1). the right deciduous second molar (dm2) exhibits a protostylid, although it is only weakly developed, consisting primarily of a raised fovea that is low and flat with a small indentation that is deep, nestled figure 3. a well-developed, oblong anterior fovea can be observed on all left permanent molars (m1, m2 and m3, from left to right) of montmaurin, albeit its expression differs. note the absence of the entoconulid and metaconulid (cusps 6 and 7, respectively). 9 dental anthropology 2017 │ volume 30 │ issue 01 within the buccal groove separating the protoconid and hypoconid (asudas grade 1). there are a total of five cusps evident on the right deciduous second molar (dm2), including a pronounced hypoconulid (asudas grade 5). in addition, there is a large metaconulid with a free apex situated within the lingual groove that separates the metaconid and entoconid (asudas grade 4) on the right second deciduous molar (dm2). roc de marsal the relatively complete skeleton of the roc de marsal child, has been aged to approximately three years (heim, 1976; minugh-purvis, 1988; williams, 2013; williams and cofran, 2016). the deciduous dentition is fully erupted, and only minimal attrition characterizes the deciduous molars. the permanent first molar crowns (m1 and m1) can be seen fully developed and embedded within the crypts. on the right and left maxillary deciduous first molars (dm1), wear facets are visible on the hypocone. there are four cusps on both the right and left deciduous first molars (dm1). a large distal groove separates the metacone, which is rather small, but is represented as an independent cuspule (asudas grade 2) (see fig. 4) from the hypocone, which is poorly-developed (asudas grade 1) on both deciduous first molar (dm1) antimeres. on the hypocone of the deciduous second molar (dm2) a large wear facet is evident, stronger on the left than the right, and a deep cleft separates the hypocone and the trigone. there are five cusps evident on this dental element. these include a metacone, which is pronounced in size on the right (asudas grade 5), but much smaller on the left antimere (asudas grade 3). the hypocone on the second deciduous molar (dm2) is larger on the left (asudas grade 4) than on the right (asudas grade 3). a weak metaconule exists on both deciduous second molars (dm2), although, like the hypocone, it is larger on the left (asudas grade 2) than on the right (asudas grade 1). on the deciduous second molar (dm2), a well-developed and independent carabelli’s cusp is evident (asudas grade 7) on both sides (see fig. 4). small wear facets exist on the buccal cusps of the mandibular deciduous first molars (dm1), although they are deeper on the right than on the left. on the deciduous first molar (dm1) an elongated and deep anterior fovea is present, bordered by a welldeveloped mesial ridge (asudas grade 4) on right and left sides. on the right, the cusp number is four, whereas the left deciduous first molar (dm1) presents five cusps. similar to the mandibular deciduous first molar (dm1), small wear facets can be observed on the buccal cusps of the deciduous second molars (dm2), although they are more extensive on the right than the left. the metaconid central ridge is deflected in a distal direction, although, it does not reach the entoconid (asudas grade 2) on the left second deciduous molar (dm2). on the right, the deflecting wrinkle is more weakly developed (asudas grade 1). on the right deciduous second molar (dm2), a protostylid can be observed as a full cusp, represented on the buccal surface of the protoconid as a buccal groove (asudas grade 6). a hypoconulid exists on right and left deciduous second molars (dm2). however, it is medium in size on the right (asudas grade 3) and small on the left (asudas grade 2). on the left deciduous second molar (dm2), a small metaconulid can be observed (asudas grade 2). scladina 1-4a scladina 1-4a comprises right and left demifigure 4. the roc de marsal right maxillary deciduous first and second molars (dm1 and dm2) exhibit a number of traits, including a small hypocone (a) on the deciduous first molar (dm1), and a pronounced carabelli’s cusp (b) on the deciduous second molar (dm2). 10 dental anthropology 2017 │ volume 30 │ issue 01 mandibles, a right maxillary fragment as well as 11 teeth from a single older child, aged to 8 to 11 years (smith et al., 2007, 2014; toussaint et al. 2011, 2014; williams, 2013; toussaint, 2014; williams and cofran, 2016). the deciduous teeth examined here include the right maxillary molars (dm1 and dm2). three permanent molars are also represented. these include the right maxillary second molar (m2) and the right mandibular first and second molars (m1 and m2). scores for these teeth using the asudas are reported by toussaint (2014); the two sets of scores present more similarities than differences. the right maxillary deciduous first molar (dm1) of scladina 4a-7 is substantially worn and exhibits a small metacone (asudas grade 3) (toussaint, 2014). the cusp number of the deciduous first molar (dm1) is three. the right maxillary deciduous second molar (dm2) of scladina 4a-5 is moderately worn (toussaint, 2014). dentine exposures exist on the protocone and hypocone surfaces. the metacone is larger on the deciduous second molar (dm2) (asudas grade 4) than on dm1. the hypocone can be described as rather large (asudas grade 4) (toussaint, 2014). the right maxillary permanent second molar (m2) of scladina 4a-3 is unerupted and the tooth crown is rectangular in shape (toussaint, 2014). the paracone is large, and both the metacone and hypocone are present, although they differ in grade. similar to the deciduous second molar (dm2), the permanent second molar (m2) has a well-developed metacone (asudas grade 4), although the hypocone can be characterized as relatively smaller in size (asudas grade 3). between the hypocone and metacone of the permanent second molar (m2), a metaconule can be observed, although it is small (asudas grade 3). the protocone features a small “y” indentation on the lingual surface indicative of a rudimentary carabelli’s trait (asudas grade 3). the mandibular permanent first and second molars (m1 and m2) of scladina 4a-1 are associated with the right demi-mandible. there are wear facets present on the permanent first molar (m1); wear is greatest on the protoconid, followed by the hypoconid. on the permanent first molar (m1), a fovea exists within the buccal groove separating the protoconid and the hypoconid. however, it cannot be described as a true protostylid (asudas grade 1). a hypoconulid can be observed, and is rather large (asudas grade 4) (toussaint, 2014). the permanent second molar (m2) is not fully erupted, and exhibits a complex occlusal morphology (toussaint, 2014). a tall mesial ridge borders an elongated and deep anterior fovea on the permanent second molar (m2) (asudas grade 4). the groove pattern indicative of the “+” configuration can be discerned. there are six cusps on the second molar (m2), including a small hypoconulid (asudas grade 2). the six cusps also include a tuberculum sextum, although it is substantially smaller than the hypoconulid (asudas grade 1). ecogeogrpahy there are a number of differences in dental morphology across geographic regions (table 2). for example, in the mediterranean (hortus), the metacone and hypocone are larger on maxillary deciduous and permanent first molars (dm1 and m1) than in the other regions. on the mandibular teeth, individuals from hortus differ from montmaurin of the pyrenees in the expression of an anterior fovea, protostylid, entoconulid, and metaconulid on the permanent third molar (m3). the presence of a metaconule on maxillary deciduous and permanent first molars (dm1 and m1) is unique to the meuse river basin of belgium, as is cusp number on the mandibular deciduous and permanent first molars (dm1 and m1). the pyrenees and southwest france do not exhibit any dental traits that are lacking representation in the other ecogeographic regions (table 2). dental traits that are expressed in all of the ecogeographic regions include the anterior fovea on the deciduous and permanent first molars (dm1 and m1), which is found on a total of 16 teeth (table 2). additionally, a cusp number of 5+ and the presence of a hypoconulid on the deciduous and permanent second molars (dm2 and m2) are expressed in all ecogeographic regions (table 2). dental traits that appear in the mediterranean, pyrenees, and the meuse river basin of belgium, but not in southwest france include the development of the protostylid and hypoconulid on the deciduous and permanent first molars (dm1 and m1), and a pronounced anterior fovea on the deciduous and permanent second molars (dm2 and m2) (table 2). the pyrenees and mediterranean sites share 11 traits in common, versus five traits shared between the mediterranean and southwest france. the pyrenees and southwest france share four traits in common (table 2). the dental traits that distinguish ecogeographic regions include the expression of the m1 hypocone and metaconule on the maxillary molars, and the entoconulid and metaconulid on mandibular molars. the expression of the metacone, anterior fovea, and mandibular molar cusp numbers are the most similar across ecogeographic regions. chronology all of the dental features present in the older period 11 dental anthropology 2017 │ volume 30 │ issue 01 tooth type trait trait presence mediterranean meuse river basin pyrenees southwest france dm1 & m1 (n=7) cusp number score 5+ present (n=1) metacone score 4-5 present (n=1) hypocone score 4-5 present (n=1) dm2 & m2 (n=7) cusp number score 4+ present (n=1) present (n=4) metacone score 4-5 present (n=3) present (n=3) hypocone score 2-5 present (n=3) present (n=4) carabelli score 5-7 present (n=1) present (n=4) cusp 5 score 1-5 present (n=1) present (n=4) dm1 & m1 (n=16) anterior fovea score 2-4 present (n=2) present (n=1) present (n=2) present (n=3) cusp number score 6+ present (n=1) mid-trigonid crest score 1 present (n=1) present (n=3) protostylid score 1-7 present (n=1) present (n=2) present (n=1) cusp 5 score 3-5 present (n=3) present (n=1) present (n=3) cusp 6 score 1-5 present (n=1) cusp 7 score 1-4 present (n=3) present (n=1) dm2 & m2 (n=11) anterior fovea score 2-4 present (n=2) present (n=2) present (n=2) cusp number score 5+ present (n=2) present (n=2) present (n=1) present (n=1) mid-trigonid crest score 1 present (n=2) present (n=2) protostylid score 1-7 present (n=1) present (n=1) present (n=2) cusp 5 score 1-5 present (n=2) present (n=2) present (n=1) present (n=3) cusp 6 score 1-5 present (n=2) present (n=1) cusp 7 score 1-4 present (n=4) present (n=1) present (n=2) m3 (n=5) anterior fovea score 2-4 present (n=3) cusp number score 5+ present (n=3) present (n=1) mid-trigonid crest score 1 present (n=1) present (n=1) protostylid score 1-7 present (n=1) cusp 5 score 1-5 present (n=3) present (n=1) cusp 6 score 1-5 present (n=3) cusp 7 score 1-4 present (n=2) table 2. dental trait comparison by ecogeographical region. 12 dental anthropology 2017 │ volume 30 │ issue 01 are also found in the younger one, with the exception of the hortus assemblage which lacks carabelli’s trait where it could be observed (hortus viii) (table 3), corroborating de lumley (1973). dental features that are present in late mis 4 and mis 3, but absent in scladina 1-4a, include the presence of a metaconule and a pronounced expression of the hypocone and metacone. on the maxillary deciduous and permanent second molars (dm2 and m2), scladina 1-4a lacks a cusp number of 4+ and a welldeveloped carabelli’s feature, as noted by toussaint (2014). the older time period also lacks more than five cusps on mandibular deciduous and permanent first molars (dm1 and m1), and on the mandibular deciduous and permanent second molars (dm2 and m2), a metaconulid is not observed. on the third molar (m3), montmaurin of the older period differs from the younger hortus remains, by lacking a pronounced anterior fovea, and any expression whatsoever of a protostylid, entoconulid, and metaconulid (table 3). on the maxillary molars, no obvious difference is found between older and younger periods, with the possible exception of carabelli’s trait (table 3). the dental features which may differentiate these broad chronological categories of older and younger include the expression of the hypoconulid, the entoconulid, and metaconulid (table 3). the dental traits that are the most similar across chronological periods include the expression of the anterior fovea and tooth type trait trait presence older younger dm1 & m1 (n=7) cusp number score 5+ present (n=1) metacone score 4-5 present (n=1) hypocone score 4-5 present (n=1) dm2 & m2 (n=7) cusp number score 4+ present (n=5) metacone score 4-5 present (n=2) present (n=4) hypocone score 2-5 present (n=2) present (n=5) carabelli score 5-7 present (n=5) cusp 5 score 1-5 present (n=1) present (n=4) dm1 & m1 (n=16) anterior fovea score 2-4 present (n=2) present (n=6) cusp number score 6+ present (n=1) mid-trigonid crest score 1 present (n=3) present (n=1) protostylid score 1-7 present (n=2) present (n=2) cusp 5 score 3-5 present (n=4) present (n=3) cusp 6 score 1-5 present (n=1) cusp 7 score 1-4 present (n=4) dm2 & m2 (n=11) anterior fovea score 2-4 present (n=3) present (n=3) cusp number score 5+ present (n=2) present (n=4) mid-trigonid crest score 1 present (n=2) present (n=2) protostylid score 1-7 present (n=1) present (n=3) cusp 5 score 1-5 present (n=2) present (n=6) cusp 6 score 1-5 present (n=1) present (n=2) cusp 7 score 1-4 present (n=7) m3 (n=5) anterior fovea score 2-4 present (n=3) cusp number score 5+ present (n=1) present (n=3) mid-trigonid crest score 1 present (n=1) present (n=1) protostylid score 1-7 present (n=1) cusp 5 score 1-5 present (n=1) present (n=3) cusp 6 score 1-5 present (n=3) cusp 7 score 1-4 present (n=2) table 3. dental trait comparison by site chronology. 13 dental anthropology 2017 │ volume 30 │ issue 01 protostylid on the mandibular molars, and cusp number and hypocone size on the maxillary first molars (table 3). discussion anterior fovea the anterior fovea appears with near ubiquity in the neanderthals (bailey, 2006), and other pleistocene humans (hrdlička, 1924; turner et al., 1991). however, variation is also observed. for example, the anterior fovea is not as deep or distinct in hortus ii as is observed on montmaurin and malarnaud. additionally, the anterior fovea of the first and second molars (m1 and m2) of montmaurin is smaller than that observed on the first molar (m1) of malarnaud. it is prominent on the deciduous first molars (dm1) of pech de l’azé 1 and roc de marsal. bailey (2006) notes an inter-correlation between the presence of an anterior fovea and the mid-trigonid crest. this relationship was noted in some individuals, such as hortus iv, hortus v, and montmaurin, but not others (table 2). entoconulid and metaconulid the entoconulid and metaconulid, also known as cusp 6 and cusp 7, respectively, are routinely absent in the pyrenees sample, whereas these accessory cusps are present in the meuse river basin of belgium category (table 2). although the entoconulid is absent in the individuals from southwest france, the metaconulid is present. both of these cusps are found in hortus for the second molars (m2); on the first molars (m1), only the metaconulid can be observed. bailey (2006) observes rather low frequencies of cusp 6 and cusp 7 (20-40%), with the exception of the entoconulid in the second and third molars (m2 and m3), which approaches 50%. in this study, the metaconulid occurs more often than does the entoconulid. hypocone the hypocone of the maxillary first molars (dm1 and m1) differentiates the ecogeographic groupings (table 3). this contrast is based primarily on the reduced expression of this feature in southwest france (pech de l’azé 1 and roc de marsal) and the meuse river basin of belgium (engis 2) contrasting to the enlarged (m1) hypocone in hortus viii. southwest france and the meuse river basin of belgium are aligned in other features that suggest more similarity than expected from such distant locations. bailey (2006) notes that the hypocone is usually present and enlarged in neanderthals. this is certainly true of hortus viii who expresses a large hypocone (lumley, 1973), but not the deciduous molars of this study. carabelli’s cusp carabelli’s trait is noted often in this study, particularly on the deciduous second molars where its strongest expression is observed. bailey (2006) finds that it also occurrs relatively consistently in neanderthals in both first (68%) and second molars (50%), corroborating the observations noted for southwest france and the meuse river basin of belgium, but not in hortus (table 2). additional considerations zubov (1992) reports a prevalence of the midtrigonid crest (epicristid) on neanderthal mandibular molars. only in the pyrenees is there a consistent presence of this dental trait across the molar row; although, it is also noted in the meuse river basin of belgium (see table 2). however, it appears to be engis 2, presumably from the younger mis 3, rather than scladina 1-4a (mis 5), which exhibits a midtrigonid crest. bailey (2006) reports the expression of at least five cusps on the molars is nearly ubiquitous in neanderthals, an observation corroborated in this study (table 2). the rarity of the expression of a deflecting wrinkle in neanderthals (bailey, 2006) is supported here as it is present only in hortus ii, malarnaud, and roc de marsal. in addition, the “y” groove pattern for m1 is relatively widespread in neanderthals as reported in bailey (2006), and is found in engis 2, hortus ii, scladina 1-4a, and montmaurin. bailey (2006) suggests the “x” groove pattern for m2 is relatively common, which in this study is expressed in hortus iv and montmaurin. it is evident that the meuse river basin of belgium is not distinct (table 2), at least in the younger time period, as it shares several traits in common with neanderthals from southwest france. the two sites closest in proximity (mediterranean and pyrenees) are not the most similar, suggesting ecogeographic distance fails to account for all the differences among regions. the fact that all of the traits examined are represented in the younger category (table 3) suggests that chronology does explain some of the variation, at least for mandibular traits, although a greater number of individuals are included in the younger category. for the maxillary molars, only carabelli’s trait differentiates the older/ younger categories (table 3). conclusions the expression of the anterior fovea is common in neanderthals (lumley, 1973; bailey, 2000, 2006). it is often found on mandibular deciduous and permanent molar rows, and its presence on m1 increases 14 dental anthropology 2017 │ volume 30 │ issue 01 the chance that it will be present on both m2 and m3 (fig. 3). the anterior fovea is expressed on deciduous mandibular molars, such as in pech de l'azé 1, roc de marsal, and engis 2, as is a prominent carabelli’s cusp. other features such as the expression of the entoconulid and metaconulid are found on the permanent molars in the hortus assemblage and in engis 2, but not in the pyrenees. maxillary molar hypocone size and the presence of a metaconule differ between mediterranean hortus viii on the one hand, and southwest france and the meuse river basin of belgium on the other. montmaurin and malarnaud from the pyrenees region resemble one another in the expression of traits on mandibular m1 and are dissimilar to scladina 1-4a. likewise, hortus ii and hortus iv resemble one another, although hortus ii and hortus v are younger (phase v) than hortus iv (phase iv) (lumley, 1973). however, they are not identical, and hortus iv and hortus v also share traits to the exclusion of hortus ii, suggesting ecogeography alone does not account for the variation in the expression of dental features. chronology may account for the absence in mis 7 to 5 of 6+ cusps in mandibular molars, the expression of a well -developed entoconulid and metaconulid, and a pronounced carabelli’s feature, all of which are observed in late mis 4/mis 3. acknowledgments it is with much gratitude that the following curators are thanked for their permission to examine the neanderthal fossils featured here: aurélie fort and liliana huet, musée de l'homme; marie-antoinette de lumley, gaël becam, and tony chevalier, centre européen de recherches préhistoriques de tautavel; jean-jacques cleyet-merle, musée national de préhistoire les eyzies-de-tayac; valentin fischer, université de liège, and dominique bonjean and michel toussaint, scladina cave archaeological centre. the image utilized in figure 4 featuring roc de marsal belongs to the collections of the musée national de préhistoire, les eyzies, dordogne, france, and was used with the permission of jean-jacques cleyetmerle. funding for this project was received by fulbright-belgium and the commission for educational exchange between the united states, belgium, and luxembourg. literature cited bailey s.e. (2000). dental morphological affinities among late pleistocene and recent humans. dental anthropology, 14, 1–8. bailey s.e. (2002). a closer look at neanderthal postcanine dental morphology. i. the mandibular dentition. anatomical record, 269, 148–156. bailey s.e. (2004). a morphometric analysis of maxillary molar crowns of middle-late pleistocene hominins. journal of human evolution, 47, 183– 198. bailey s.e. (2006). beyond shovel-shaped incisors: neandertal dental morphology in a comparative context. periodicum biologorum, 108, 253–267. crégut-bonnoure é., boulbes n., guérin c., pernaud j., tavoso a., cammas r. (2010). le contexte géomorphologique et faunique de l’homme de montmaurin (haute-garonne). préhistoires méditerranéennes, 1, 35–85. di modica k., toussaint m., abrams g., pirson s. (2016). the middle palaeolithic from belgium: chronostratigraphy, territorial management and culture on a mosaic of contrasting environments. quaternary international, 411, 77–106. guérin g., discamps e., lahaye c., mercier n., guibert p., turq a., dibble h.l., mcpherron s.p., sandgathe d., goldberg p., jain m., thomsen k., patou-mathis m., castel j.-c., soulier m.-c. (2012). multi-method (tl and osl), multimaterial (quartz and flint) dating of the mousterian site of roc de marsal (dordogne, france): correlating neanderthal occupations with the climatic variability of mis 5-3. journal of archaeological sciences, 39, 3071–3084. hanihara k. (1961). criteria for classification of crown characters of the human deciduous dentition. journal of the anthropological society of nipon, 69, 27–45. heim j.-l. (1976). les néandertaliens en périgord. in h. de lumley (ed.), la préhistoire française. tome i: les civilisations paléolithiques et mésolithiques de la france (pp. 578–583). paris: éditions du cnrs. hrdlička a. (1924). new data on the teeth of early man and certain fossil european apes. american journal of physical anthropology, 3, 109–132. hublin j.-j., roebroeks w. (2009). ebb and flow or regional extinctions? on the character of neandertal occupation of northern environments. comptes rendus palevol, 8, 503–509. hublin j.-j., bailey s., olejniczak a., smith t., verna c., sbihi-alaoui f.z., zouak m. (2012). dental evidence from the aterian human populations of morocco. in j.-j. hublin & s. mcpherron (eds.), modern origins: a north african perspective (pp. 189–204). dordrecht: springer. kelso j., prüfer k. (2014). ancient humans and the origin of modern humans. current opinion in genetics and development, 29, 133–138. lalueza-fox c., rosas a., estalrrich a., gigli e., campos p.f., garcía-tabernero a., garcíavargas s., sánchez-quinto f., ramírez o., civit s., bastir m., hugnet r., santamaría d., gilbert m.t.p., willerslav e., de la rasilla m. (2011). ge15 dental anthropology 2017 │ volume 30 │ issue 01 netic evidence for patrilocal mating behavior among neandertal groups. proceedings of the national academy of sciences usa, 108, 250–253. lumley m.-a. de. (1973). anténéandertaliens et néandertaliens du bassin méditerranéen occidental européen. marseille: université de provence. lumley m.-a. de. (1976). les néandertaliens dans le midi méditerranéen. in h. de lumley (ed.), la préhistoire française. tome i: les civilisations paléolithiques et mésolithiques de la france (pp. 567– 577). paris: éditions du cnrs. minugh-purvis n. (1988). patterns of craniofacial growth and development in upper pleistocene hominids. (ph.d. dissertation), university of pennsylvania, philadelphia, pa. patte e. (1959). la dentition des néandertaliens. annales de paléontologie, 45, 1–162. petite-marie n., ferebach d., bouvier j.-m., vandermeersch b. (1971). france. in k.p. oakey, b.g. campbell & t.i. molleson (eds.), catalogue of fossil hominids. part ii: europe (pp. 71–187). london: trustees of the british museum (natural history). pirson s., court-picon m., dambon f., balescu s., bonjean d., laesarts p. (2014). the palaeoenvironmental context and chronostratigraphic framework of the scladina cave sedimentary sequence (units 5 to 3 sup). in m. toussaint & d. bonjean (eds.), the scladina 1-4a juvenile neandertal (andenne, belgium): palaeoanthropology and context (pp. 69–92.). andenne, belgium: études et recherches archéologiques de l’université de liège. semal p., toussaint m., maureille b., rougier h., crevecoeur i., balzeau a., bouchneb l., louryan s., de clerck n., rausin l. (2005). numérisation des restes humains néandertaliens belges. préservation patrimoniale et exploitation scientifique. notae praehistoricae, 25, 25–38. semal p., rougier h., crevecoeur i., jungels c., flas d., hauzeur a., maureille b., germonpré m., bocherens h., pirson s., cammaert l., de clerk n., hambucken a., higman t., toussaint m., van der plicht j. (2009). new data on the late neandertals: direct dating of the belgian spy fossils. american journal of physical anthropology, 138, 421 –428. smith t.m., toussaint m., reid d.j., olejniczak a.j., hublin j.-j. (2007). rapid dental development in a middle paleolithic belgian neanderthal. proceedings of the national academy of sciences usa, 104, 20220–20225. smith t.m., reid d.j., olejniczak a.j., tafforeau p.t., hublin j.-j., toussaint m. (2014). dental development in and age at death of the scaldina 1-4a juvenile neandertal. in m. toussaint & d. bonjean (eds.), the scladina 1-4a juvenile neandertal (andenne, belgium): palaeoanthropology and context (pp. 155–166). andenne, belgium: études et recherches archéologiques de l’université de liège. soressi m., jones h.l., rink w.j., maureille b., tillier a.-m. (2007). the pech-de-l’azé i neandertal child: esr, uranium series and ams 14c dating of its mta type b context. journal of human evolution, 52, 455–466. tillier a.-m. (1983). le crâne d’enfant d’engis 2: un exemple de distribution des caractrès juvéniles, primitifs et néandertaliens. bulletin société royale belge d’anthropologie et de préhistoire, 94, 51–75. toussaint m. (2014). the dentition of the scladina 14a juvenile neandertal. in m. toussaint & d. bonjean (eds.), the scladina 1-4a juvenile neandertal (andenne, belgium): palaeoanthropology and context (pp. 233–306). andenne, belgium: études et recherches archéologiques de l’université de liège. toussaint m., semal p., pirson s. (2011). les néandertaliens du bassin mosan belge: bilan 20062011. in m. toussaint, k. di modica & s. pirson (eds.), le paléolithique moyen de belgique. mélanges marguerite ulrix-closset (pp. 149–196). liège: etudes et recherches archéologiques de l'université de liège, 128, les chercheurs de la wallonie. hors-série 4. toussaint m., bonjean d., pirson s. (2014). the scladina 1-4a juvenile neandertal: a synthesis. in m. toussaint & d. bonjean (eds.), the scladina 1-4a juvenile neandertal (andenne, belgium): palaeoanthropology and context (pp. 409–418). andenne, belgium: études et recherches archéologiques de l’université de liège. turner c., nichol c., scott g. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in m. kelley & c. larsen (eds.), advances in dental anthropology (pp. 13–31). new york: wiley liss. twiesselmann f. (1971). belgium. in k.p. oakey, b.g. campbell & t.i. molleson (eds.), catalogue of fossil hominids. part ii: europe (pp. 5–13). london: trustees of the british museum (natural history). williams f.l. (2013). neandertal craniofacial growth and development and its relevance for modern human origins. in f. smith f & j. ahern (eds.), the origins of modern humans: biology reconsidered (pp. 253–284). hoboken, nj: wiley. williams fl, cofran z. (2016). postnatal craniofacial ontogeny in neandertals and modern humans. american journal of physical anthropology, 159, 394 –409. zubov a.a. (1992). the epicristid or middle trigonid crest defined. dental anthropology. newsletter, 6, 9 liversidge 2014.5 26 dental anthropology 2014 │ volume 27 │ issues 01 and 02 this is terrific book, detailing the important longitudinal dental and growth study in yuendumu (1951-1971), how it came about, the logistics, the principle investigators and what knowledge has been gained. this is a readable book, with a fascinating historical account of the background to the study, the complexity and difficulty collecting longitudinal data in a remote, inhospitable region. all four authors write from direct experience, particularly tasman brown and grant townsend. the book has nine chapters and three appendices and is richly illustrated with photographs, tables and diagrams. the chapters fall into three sections and a bibliography. the first part chronicles early expeditions to the northern territory and the logistics of the field trips of the longitudinal study. the middle section summarises the research findings of the occlusal development and function of teeth and facial growth patterns of the warlpiri people. the third section is about the people involved and an account of more recent outcomes and collaborations using this valuable resource of curated records. the documented list of the hundreds of publications, theses and films is a valuable reference. in addition, a useful appendix of 24 summary tables of growth variables from 5-20 years in half year intervals is provided. the book is supported by an open access electronic version. the major strength of this book is the way it brings together the historical context, the logistic organisation of the field trips and challenges of data collection during this period. it also describes the extensive impact of this research in the understanding of dental anthropology and cranio-facial growth. these two chapters build on what must be one of the founding studies of dental anthropology in the modern era i.e. campbell’s thesis on the dentition and palate of the australian aboriginal (1925). the legacy of knowledge from this longitudinal study in yuendumu touches most aspects relating to the dentition and developing craniofacial complex. the teeth of australian aboriginals are characterized by larger crown diameters than most other living groups and ample dental arch dimensions. dental crown features form a characteristic australian dental complex that includes carabelli trait and metaconules (cusp 5) on maxillary molars, cusps 6 and 7 on mandibular molars and shovel shaped incisors. tooth use as tools and extensive occlusal and interproximal tooth wear are also features. mid-facial prognathism is common, with relative protrusion of the mid-facial region particularly prominent in the alveolar bone, allowing wide excursions of the mandible during mastication. less malocclusion and tooth crowding occurs than in other populations. the longitudinal study has documented the age of eruption and exfoliation of deciduous and permanent teeth as well as facial growth. lip and tongue pressure in relation to occlusion, occlusal wear, function in the worn dentition and the function of cusps have also been investigated. more recent studies document the oral health and general health in yuendumu aboriginals at the present time and the increasing dental caries experience as food habits changed. human longitudinal growth studies in general and their future are discussed. these two chapters are supported by an excellent biography of publications and theses. the appendices and online access of an ebook also make this an important resource that will be valuable to anyone with an interest in dental anthropology, dental morphology or craniofacial growth. the only limitation of this book is that the two chapters on occlusal development and function and facial growth in the warlpiri are too short as, in my view, they could be a volume in their own right. the only related book is about the fells longitudinal study of human growth, maturation and body composition (roche 1992). the yuendumu legacy is written in a more narrative style and because of the unique timing collecting data on previous hunter-gatherers and the focus on the dentition, this book will be of particular interest to readers of dental anthropology journal. it is a privilege to have worked on this material and dental anthropologists the world over, owe a debt of gratitude to campbell and barrett as well as the authors, for collecting, documenting and curating the records that make up the physical legacy that continue to contribute to the understandbook review legacy of a longitudinal growth study in central australia. by tasman brown, grant c townsend, sandra k pinkerton, james r rogers. published in adelaide by university of adelaide press, 2011. pp. 327. isbn: 978-0-9807230 -9-0, price a$35.00, paperback. 978-0-98707300-6, free, e-book pdf. 27 book reviews dental anthropology 2014 │ volume 27 │ issues 01 and 02 ing of the complexities of the developing dentition and cranio-facial region. helen liversidge institute of dentistry turner street, london, united kingdom e1 2ad email: h.m.liversidge@qmul.ac.uk literature cited campbell td. 1925. dentition and palate of the australian aboriginal. adelaide: univ. adelaide. roche af. 1992. growth, maturation and body composition. cambridge studies of biological anthropology. cambridge university press, cambridge. correction the author would like to apologise for an error in calculating standard deviation using logistic regression in the publication of liversidge hm. 2010. demirjian stage tooth formation results from a large group of children. dental anthropology 23:16-24. the standard logistic distribution has a variance of π² ÷ 3 and standard deviation of π² √ 3 (greene and hensher 2010). this means that standard deviation values in tables i and ii are incorrect and require a correction factor. the standard deviation should be corrected by multiplying with 1.814 year. literature cited greene wh, hensher da. 2010. modeling ordered choices. a primer. cambridge: cambridge university press. page 16. 57 dental anthropology 2021 │ volume 34│ issue 02 this edited volume is among the latest to demonstrate how current bioarchaeological research sup ports the integration of robust, data-driven case studies with broader anthropological scholarship focused on marginalization. the volume includes chapters that interact with race, class, gender normativity, and sexuality. contributions model a range of current best practices in bioarchaeology. this includes advancing north american research not centering the united states, along with multi-authored and international collaborations. furthermore, studies present innovative models of public and community engagement that are as varied as the definitions of marginalization employed by contributors throughout the book. mant and holland organize the types of marginalization covered in the book into the following categories: peripheralization, a loss of individuality, positivity through difference and the absence of context and forgetting. these are somewhat limiting descriptions, given that contributions present a broad range of conditions of marginalization and how they are constructed, experienced, and change across space and time. the first case in the book sets the tone for the complex ways that marginalization is tied to socio-historical, political and economic processes including the interplay of local and extra-local dynamics. “mummies, memories, and marginalization: the changing social roles of a mummy from ancient to modern times,” looks at shifts in meaning attributed to the “lady hudson” roman-era mummy as she moves from the hands of collectors, to museums and ultimately the university of western ontario. encounters with different publics go hand in hand with this circulation that bears on how her identity is shaped, and how people’s identities are shaped by their engagement with her. these dynamics are different with collectors and museum goers than they are with university students learning from studying her. nelson discusses lady hudson’s marginalization according to her personal, mortuary, curated and bioarchaeological identities. the extent to which these identities can be fully realized is based on the availability of information about her as an individual, changes in ethical perspectives on the acquisition of human remains and the technologies available for scientific translation. therefore, her marginalization in various spheres differs according to how she is being engaged and consumed by researchers and various publics across space and time. the fourth chapter, “looking into the eyes of the ancient chiefs of shíshálh: the osteology and facial reconstructions of a 4000-year-old high-status family” addresses similar dynamics of marginalization according to how personal and curated identities are shaped. clark et al. detail a case at the intersection of art, science, and community partnership that demonstrates how interpretations of past populations bear on the identities of descendants. approaches to conducting research on past populations can contribute to the marginalization of their descendants. with that in mind, clark et al. adopted a research model that involved bringing visibility to 4000 year-old high-status individuals unearthed at the kwenten makw’ali site that involved shíshálh descendants in the excavation, facial reconstruction, and museum exhibition. the presence of archaeologists from the shíshálh nation emphasizes that the communityresearch binary implicit in community engagement discourses belies the reality that descendants are also researchers. several chapters present cases illustrating how bioarchaeological studies can contribute to anthropological studies of people’s relationship to the state and state-society relations. the last chapter by hackett and colleagues, “innovation in population health intervention research: a historical perspective,” addresses how the past itself can be marginalized in ways that obscure its role in current conditions of the state and disparities that people experience within it. the case centers on treating the past as a “laboratory” from which to collect health and health policy data to understand how continuities and changes in the distribution of resources at local and state levels over time impact health. heather battles speaks to marginalization arising from “forgotten historical moments” in her chapter, “in the shadow of war: the forgotten 1916 polio epidemic in new zealand.” one of the many unique contributions that this chapter makes to the volume is a discussion of the relationship that one's body has to the state. battles demonstrates the context that bioarchaeology provides for understanding the long-term impact of historical events, including book review bioarchaeology of marginalized people. edited by madeleine l. mant and alyson jaagumägi holland. academic press, an imprint of elsevier. 2019. 300 pp., $84.95 (paperback). isbn: 9780128152249. 58 dental anthropology 2021 │ volume 34│ issue 02 how state formation and bodily formations are constitutive of one another. redfern and hefner’s ““officially absent but actually present”: bioarchaeological evidence for population diversity in london during the black death, ad 1348–50” also takes up the issue of how the ability for people to be seen (or not) is impacted by how the state is conceptualized. for instance, redfern and hefner note how sexual taboos and normalized historical interpretations of the medieval period foster the "official" absence of african-descendant people." their study demonstrates how bioarchaeological research can play a unique role in bringing visibility to "forgotten" groups of people through dna and isotope analysis. similarly, shields wilford and gowland illustrate how changes in welfare ideologies and policies impacted the health of postmedieval workhouse inmates. their analysis also highlights how the changes in poor laws lead to particularly gendered health disparities, given overseers’ willingness to aid single mothers and widows. in “health in equity and spatial divides: infant mortality during hamilton, ontario’s industrial transition, 1880–1912,” ludlow and hackett also present a case on the gendered aspects of marginalization. discourses around infant mortality in late 19th-early 20th century ontario targeted mothers as the cause. however, the authors provide a counter-illustration of how changes in the social and physical environment correlated with diarrheal and respiratory-related infant mortality. their findings emphasize the fallacy of ties between health disparities and inherent biological or behavioral differences. lovell and palichuk round out gender and health discussions in the volume with “task activity and tooth wear in a woman of ancient egypt.” their case focuses on a woman excavated from ancient mendes (egypt) with a unique dental wear pattern. difference between her wear pattern and those found among women in more domesticated contexts suggest that the woman was using her teeth as a tool for a specialized craft. the interpretive possibilities demonstrate how bioarchaeological research fits within current anthropo logical research that lends to disrupting notions of gender normativity. carlina de la cova’s case study of the terry collection focuses on the significance of the great migration to the presence of african americans in the sample. “marginalized bodies and the construction of the robert j. terry anatomical skeletal collection: a promised land lost,” argues that migration reflects the oppression taking place in the south, but also the embodiment of human agency that led blacks to seek better social and economic conditions elsewhere. this is an important contribution to scholarship on a well-studied populations largely used to illustrate disparities. de la cova’s chapter also addresses the way that the identities of skeletal collections shape and are shaped by their architects and researchers. doubeck and grauer address this latter point in their chapter, “exploring the effects of structural inequality in an individual from 19th century chicago.” the authors offer a case study of an individual from the field museum’s anatomical collection with a unique emphasis on researcher “appreciation.” specifically, the authors use appreciation as a frame for deconstructing the notion that a researcher’s engagement with human remains is purely scientific. this complements the detailed social context they provide for the skeleton as part of an agenda to expand our analyses of marginalized populations to include immigrant communities. in “marginalized by choice—kayenta pueblo communities in the southwest (ad 800–1500),” debra mar tin offers a unique perspective on the agency of marginalized groups in a case focused on the kayenta of northeastern arizona. researchers interpret these groups to be marginal based on evidence of minimal interaction with surrounding political and ceremonial centers. however, martin offers a health profile indicating the material benefits of their “inward focus” in terms of social stability, fertility, and flexible subsistence. the kayenta strategy for navigating the challenges of their physical environment reminds us of the importance of complicating our understanding of marginalization as it relates to human agency. the volume is at its strongest where studies are presented in ways that lend to theoretical engagement without engaging the theory itself. the use of intersectionality is particularly sloppy, and perhaps needless for framing the presence of black ancestry in medieval europe. the sloppiness is not a matter of lacking adherence to a particular definition of intersectionality, which is a matter of debate itself. arguably, the concept is not necessary for redfern and hefner to critique assumptions about: 1) the absence of black ancestry in medieval european populations and 2) a singular experience among people identified as having black ancestry. more generally, while definitions of marginalization vary between chapters, its presentation as an exacting force is rather consistent throughout the book. apart from the martin and de la cova chapters, discussions tend not to address how agency factors 59 dental anthropology 2021 │ volume 34│ issue 02 into dynamics of marginalization. readers seeking more direct theoretical engagement can look to other recent volumes such as theoretical approaches in bioarchaeology, which includes chapters authored by several contributors to the bioarchaeology of marginalized people. none of the book’s shortcomings detract from the robust presentation of case studies, models of collaboration and appropriate marginalization of the us in a volume focused on north american bioarchaeology. this is an excellent book for undergraduates and graduates because of the accessible writing on the part of the contributors, and the excellent guidance that the editors provide in the introductory and concluding chapters. rachel watkins department of anthropology american university 22 dental anthropology 2019 │ volume 32 │ issue 02 a sub-continent of caries: prevalence and severity in early holocene through recent africans fawn carter 1* and joel d. irish 2 1 museum of the north, university of alaska 2 research centre in evolutionary anthropology and palaeoecology, liverpool john moores university here we assess how dental caries frequencies differ by time period, sex, environment, and subsistence strategy among a range of populations across subsaharan africa. severity is also briefly discussed. carbohydrate intake, adoption of agriculture, and behavioral and biological differences between the sexes and among populations all influence dental decay, so the latter can be highly informative (turner, 1979; newbrun, 1982; larsen, 1997; lukacs and largaespada, 2006; lukacs and thompson, 2008). yet, relatively few dental pathology studies have been conducted within this vast region (irish, 1993). those that have, focus largely on qualitative data or are small in spatiotemporal scope (flower, 1889; shaw, 1931; frencken et al., 1986; morris et al., 1987; solanki et al., 1991; sealy et al., 1992; mackeowen et al., 1995; steyn et al., 1998; cleaton-jones et al., 2000; ohinata and steyn, 2001; pistorius et al., 2002; steyn, 2003). the present study is much more comprehensive, covering the sub-continent from 10,000 years ago to present. at this large scale, the trends observed can work to support and/or refute those observed elsewhere in the world. the findings are discussed in terms of diet and other biocultural practices known to affect dental health. the present study focuses on four research questions: 1) how did dental caries frequencies change through time? the samples were divided into late stone age, iron age, or recent. each period was marked by a major shift in diet as new foods were introduced. 2) is there a significant difference in caries between the sexes? the literature indicates a global trend for higher frequencies in females, particularly with the advent of agriculture (caselitz, 1998; lukacs and largaespada, 2006; lukacs, 2008; lukacs and thompson, 2008; ferraro and vieira, 2010). the present results will help test whether the trend holds in sub-saharan africa. 3) how do environmental differences affect the dental caries frequencies? such differences limit what foods are present, so should have an influence. samples are divided by the ecosystem from abstract the most recognizable pathological condition of the human oral cavity is, arguably, dental caries. beyond a direct impact on oral health, caries presence (or absence) provides important data for bioarchaeologists—to help reconstruct the diet of past populations and individuals. this study explores such data in 44 samples (n=2,119 individuals, 33,444 teeth) dating between 10,000 bp and recent times across the african sub-continent. it is, to date, the most extensive investigation of its kind in this part of the world, entailing descriptions and quantitative comparisons of caries by period, environment, subsistence strategy and sex. mann-whitney u tests and factorial anova results provide expected and some unexpected findings, including: 1) a diachronic increase in caries prevalence across the sub-continent, likely related to diet change from widespread population movement; 2) savanna peoples exhibit more caries than those from other environmental regions; 3) subsistence strategy plays a major role in caries occurrence; and 4) males and females do not evidence significant differences in caries frequencies, but variation does exist in several regional groups. these findings reveal that global trends described by previous researchers often apply, though not always—so it is prudent to consider regions independently. *correspondence to: fawn carter museum of the north university of alaska fairbanks ak fmcarter@alaska.edu keywords: dental caries, africa, environment, sex, subsistence 23 dental anthropology 2019 │ volume 32 │ issue 02 which they were derived: coastal, desert, savanna/ grassland, and tropical rainforest. 4) how does subsistence strategy affect the caries rates? sub-saharan africans used a range of strategies to procure food, including hunting and gathering, pastoralism, and agriculture. because diet is determined by subsistence strategy there should be an impact. to address this likelihood and place sub-saharan african peoples in broader spatiotemporal context, samples from the current study are compared to turner’s (1979) metaanalysis of populations with different subsistence strategies. materials and methods data on caries prevalence, as well as severity in some instances, were collected from 44 samples (n=2,119 individuals; 33,444 teeth, table 1) throughout the african sub-continent by irish during the course of his dental morphological research (1993, 1997). these samples date from ca. 10,000 bp to the 20th century. the location and severity are recorded for each of the carious lesions present. caries are ranked on a scale of 1 to 4, with 1 being a small pit that does not penetrate the enamel and 4 being pulp perforation (buikstra and ubelaker, 1994). location is designated as mesial, distal, buccal, occlusal, lingual or a combination in the event of large or multiple lesions. sex was determined as m, m?, ?, f, f? by the second author using standard methods (e.g., buikstra and ubelaker, 1994). only adults (i.e., ≥18 years of age) were included in the analyses. lukacs’ (1992, 1996) caries index was calculated to adjust for antemortem tooth loss (amtl): (amtl) (% teeth with severe caries) + (teeth with caries) (teeth present) + (amtl) this method takes into account the number of teeth present with pulp exposure (severity level 4) due to dental caries. the present study compares the percentage of teeth with carious lesions; therefore, results could be skewed if amtl were not accounted for, since many teeth are removed due to toothache resulting from serious carious lesions or abscesses (lukacs, 1996). the caries data were compared using three common statistics. first, mann-whitney u tests were used to compare the percent of teeth with carious lesions for the four major categories of independent variables (i.e., period, sex, environment, subsistence). second, factorial anova accounted for significant differences among subsistence strategy, environment, time period, betweensex, or any combination of these four on the dependent variable (percentage of teeth with caries per individual). the null hypothesis of consistency was tested, followed by a series of post hoc tests (i.e., tukey) to identify significance between all combinations of the independent variables. lastly, the spearman’s rho correlation coefficient was used to simply determine any relationship between attrition and caries. higher levels of wear should correlate with fewer caries because normal attrition wears away the tooth surface before caries can form (brothwell, 1963; scott & turner, 1988; hillson, 1996; caselitz, 1998). results the mann-whitney u (table 2) and tukey (table 3) test results show a statistically significant difference (p<0.05) for each pair of time periods. the factorial anova found time period to be a significant factor for caries counts with a value of 0.005 (table 4) mann-whitney u (see table 2), tukey (see table 3) and factorial anova (see table 4) tests show no statistically significant values for caries frequency differences between the sexes. however, the bar graph (figure 2) does display a general trend of females with more carious lesions—at least for the late stone age (lsa) and iron age samples. in the recent samples males and females have equal percentages; the only significant difference is among pastoralists (not shown). anova (see table 4) results show that environment has a significant impact on caries for the lsa (0.000), recent (0.009), and combined groups (0.004). the mann whitney u (see table 2) results reveal no significant difference among environments in terms of caries counts for the iron age samples, but some differences do exist for lsa and recent samples. tukey (see table 3) results show significant difference only among the lsa samples. figure 2 illustrates the different counts of affected individuals for each environment category. not all environmental categories are represented by time period; as such, some effect on results may occur and these should be interpreted with caution. factorial anova (see table 4) results suggest that subsistence contributes to caries counts for the recent samples (0.060) and all periods combined (0.000). outcomes from the mann-whitney u (see table 2) and tukey (see table 3) tests show a difference between hunter/gatherers and pastoralists among the lsa samples (0.043) and hunter/ gatherers and agriculturalists when all periods are 24 dental anthropology 2019 │ volume 32 │ issue 02 code full name country environment time period subsistence n adr adrar bous niger savanna late stone age pastoralism 10 cha chad chad savanna recent pastoralism 31 con congo congo tropical rain forest recent agriculture 34 dbi republic of the congo congo tropical rain forest iron age agriculture 20 dcb lower congo congo tropical rain forest recent agriculture 27 dch upper congo congo tropical rain forest recent agriculture 24 dcr democratic republic of congo and ruanda democratic republic of the congo tropical rain forest recent agriculture 72 eth ethiopia ethiopia savanna recent agriculture 40 fvr fernand vaz river fernand vaz tropical rain forest iron age agriculture 50 gab gabon gabon tropical rain forest recent agriculture 39 gha ghana ghana tropical rain forest/ savanna recent agriculture 48 hay haya tanzania savanna recent agriculture 51 ibo ibo nigeria tropical rain forest/ savanna recent agriculture 54 ken kenya kenya and tanzania savanna recent agriculture 96 khe holocene early kenya kenya * late stone age hunter/gatherers 80 khoi khoikhoi south africa desert recent pastoralism 56 kku kikuyu kenya savanna recent agriculture 60 khl rumuniti in vaso narok valley kenya * late stone age * 69 mat matjes river cave south africa coast late stone age hunter/gatherers 51 ndb ndebele savanna recent pastoralism 38 ngo ngorongoro tanzania savanna late stone age * 26 ngu south africa south africa savanna recent agriculture 35 nic nigeria/cameroon nigeria and cameroon tropical rain forest/ savanna recent agriculture 54 nlt nilotic kenya and tanzania savanna recent pastoralism 24 pyg pygmy congo, gabon, and botswana tropical rain forest recent hunter/gatherers 34 san san botswana and south africa desert recent hunter/gatherers 52 sen senegambia senegal and gambia tropical rain forest/ savanna recent agriculture 42 sho south africa south africa * recent hunter/gatherers 85 sml shum laka cameroon savanna late stone age hunter/gatherers 10 som somalia somalia desert recent pastoralists 77 sot sotho south africa savanna recent agriculture and pastoralism 66 sph south africa south africa * iron age hunter/gatherers 70 swz swazi south africa * recent agriculture 58 tan tanzania and zanzibar tanzania savanna recent agriculture 45 tei taita kenya savanna recent agricutlure 51 tod togo and dahomey togo and benin tropical rain forest/ savanna recent hunter/gatherers 26 tsw tswana botswana and south africa desert recent hunter/gatherers 63 tuk tukulor senegambia savanna recent agriculture 40 upb upemba valley democratic republic of the congo tropical rain forest iron age agriculture 56 ven venda south africa savanna recent agriculture 51 wol wolmarnstad south africa grassland recent agricutlure 26 xos xosa south africa savanna recent agriculture 66 yor yoruba yoruba tropical rain forest/ savanna recent agriculture 28 zul zulu south africa savanna recent pastoralism 66 * information not available table 1. summary of samples including the current country the sample was collected from, the environment, time period, and subsistence strategy category the sample was found to best fit with, and the number of individuals from each sample. 25 dental anthropology 2019 │ volume 32 │ issue 02 significance* variable groups lsa iron age recent combined time period lsa & iron age n/a n/a n/a 0.003 lsa & recent n/a n/a n/a <0.001 iron age & recent n/a n/a n/a <0.001 sex male & female 0.113 0.113 0.564 0.803 environment desert & savanna 0.942 n/a 0.016 0.625 desert & rainforest 0.127 n/a 0.84 0.771 desert & coastal 0.397 n/a n/a 0.206 savanna & rainforest <0.001 0.226 0.007 0.842 savanna & coastal 0.018 n/a n/a 0.131 rainforest & coastal 0.031 n/a n/a 0.162 subsistence hunting/gathering & pastoralism 0.043 n/a 0.546 <0.001 hunting/gathering & agriculture n/a n/a 0.975 <0.001 pastoralism & agriculture n/a 0.51 0.134 0.654 *significant at p<0.050 table 2. results of mann-whitney u tests significance* variable groups lsa iron age recent combined time period lsa & iron age n/a n/a n/a 0.057 lsa & recent n/a n/a n/a <0.001 iron age & recent n/a n/a n/a 0.041 sex male & female 0.295 0.415 0.327 0.5 environment desert & savanna 0.965 n/a 0.156 0.941 desert & rainforest <0.001 n/a 0.538 0.583 desert & coastal 0.607 n/a n/a 0.639 savanna & rainforest <0.001 n/a 0.682 0.679 savanna & coastal 0.255 n/a n/a 0.424 rainforest & coastal <0.001 n/a n/a 0.243 subsistence hunting/gathering & pastoralism n/a n/a 0.323 0.002 hunting/gathering & agriculture n/a n/a 0.752 <0.001 pastoralism & agriculture n/a n/a 0.236 0.125 *significant at p<0.050 table 3. tukey results variable lsa iron age recent combined time period n/a n/a n/a 0.349 sex 0.082 0.675 0.708 0.836 environment <0.001 0.609 0.009 0.004 subsistence n/a 0.789 0.069 0.037 *significant at p<0.050 table 4. factorial anova results figure 2. percent of individuals affected by caries for each environment category in lsa, iron age, and recent sub-saharan african samples. see text for details. 26 dental anthropology 2019 │ volume 32 │ issue 02 combined (0.000). there is no significant difference in caries number between pastoralists and agriculturalists for any time period. figure 3 visually represents the differences between subsistence strategies by time period. lastly, the correlation between wear and caries prevalence was calculated using spearman’s correlation coefficient. the correlation of 0.012 indicates a very weak, yet positive relationship. an insignificant p-value of 0.400 was calculated. discussion 1) did caries frequencies change through time? results show a definite increase in caries rate through time. many new crops were introduced through time that may have had an impact. asian sugarcane and bananas appeared as early as the iron age and via the portuguese in the 17th century (frencken et al., 1989; irish and turner, 1997). sugarcane has a negative impact on health not only because of high sucrose levels but because of the manner in which it is eaten, which causes severe crown wear (dreizen & spies, 1952; frencken et al., 1989; irish & turner, 1997). bananas and plantains, both a significant crop in central and eastern africa (ehret, 2002), are moderately cariogenic due to their sticky and sugary structure (mundorffshrestha et al., 1994; aurore et al., 2008). several cariogenic crops from the americas were also introduced, including maize and cassava (larsen et al., 1991; hillson, 1996; ehret, 2002); most did not become widespread until the 18th century, which may account for the rise in caries between the iron age and recent samples (ehret, 2002). overall, these soft, often sticky high carbohydrate foods are much more cariogenic than the traditional african diet (hillson, 2008). 2) is the rate of caries higher among females than males? all tests suggest that an individual’s sex did not significantly contribute to the caries frequencies; that said, an examination of the bar chart (figure 1) reveals a general trend for higher frequencies in females. a common explanation for the disparity is that females collect, prepare and consume more cariogenic foods than do males (mulder, 1992). other potential causative factors include genetic and hormone differences; all are said to be accentuated in agriculturalist groups (lukacs and largaespada, 2006; lukacs, 2008), though this is not evident in the present african samples—for reasons we are continuing to investigate. 3) are there environmental differences in the caries frequencies? observing patterns is difficult because not all environmental groups are present by time period. in the iron age and recent periods, caries are more prevalent among those on the savanna. many of them would have relied on grain foods or pastoralism, i.e., the latter peoples often trade with agriculturalists for grains made into sticky porridge (forde & jones, 1950; skinner, 1973). the naturally high cariogenicity of corn and wheat (dodds, 1960; okazaki et al., 2013) combined with the sticky nature of the grain porridge potentially contributes to higher instances of caries in savanna dwellers. a high caries percentage (23%) occurs in coastal lsa samples. coastal peoples generally have fewer caries because of grit and fluoride from marine foods (walker & erlandson, 1986). sealy et al. (1992) report similar results with the oakhurst sample from the southern cape. contradictory to their results with other coast dwellers, where only 2.6% of teeth exhibit caries, 17.7% of teeth from oakhurst are affected, despite a diet rich in marine resources; the authors state that the explanation for the high rate is the lack of fluoride in local ground water. 4) does subsistence strategy affect dental health? the results obtained by factorial anova suggests that subsistence strategy is a contributing factor to caries counts when all time periods are combined. no clear pattern is evident in the bar chart (figure 3), perhaps because not all strategies are present by period. however, the high rate for recent pastoralists is interesting. as noted, pastoralists eat grains plus milk and other animal byproducts (forde & figure 3. percent of individuals affected by caries for each subsistence strategy in lsa, iron age, and recent sub-saharan african samples. see text for details. 27 dental anthropology 2019 │ volume 32 │ issue 02 jones, 1950; skinner, 1973). as well, many recent pastoralists are actually agro-pastoralists (krige & krige, 1954; skinner, 1973; zeleza, 1997). grain porridge combined with maize apparently had a negative impact on dental health (larsen et al., 1991; scherer et al., 2007). cassava would also be a starch source (ehret, 2002) that prevents carbohydrates being cleaned away to give bacteria more time to feed (lingstrom et al., 1989, larsen, 1997; hillson, 2008). a comparable caries percentage is evident in the recent hunter/gatherers and agriculturalists. perhaps this similarity is related to the fact that modern hunter-gatherers, like the san, are not limited to this lifestyle as they once were. after the arrival of europeans, many khoisan worked on farms, where they ate croprather than wild foods (reader, 1997; july, 1998). modern pygmies also often rely on agriculturalists for trade (afolayan, 2000). the increase in domesticated foods apparently caused both groups to have caries rates like those of agriculturalists. relative to turner’s (1979) analysis of different economies, the sub-saharan results are complementary. he reports 0.0-5.3% for hunter/gatherers; the sub-saharan lsa samples fall within this range (2%), but not for recent hunter-gatherers (8%). most of turner’s samples are from early archaeological sites, so were generally not influenced by an agricultural diet. recent hunter-gatherers fall within turner’s range for mixed economies (0.4-10.3%), which is likely a more adequate descriptive category. sub-saharan pastoralists (5-7%) fall within the mixed economy category, and the agriculturalists (4.0-7%) fit turner’s agriculturalist category (2.326.9%). finally, caries severity was only recorded in 469 of the total 2119 dentitions; thus, on that basis the spearman’s rho value of 0.012, though positive, is only very weakly correlated, i.e., essentially random. these results suggest here that while of interest individually, such data may be less useful in a broader study. conclusions statistically significant differences in dental caries frequencies have been observed between time periods, environmental groups, and subsistence strategies among 44 sub-saharan african samples. the introduction of new foods through time, regional specializations, and food collecting strategies have been found to potentially affect dental decay. the results from the current study imply that cultural differences can have major implications for dental health. references afolayan, f. 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(1997). brief communication: first evidence of lsamat in non-native americans: historic senegalese from west africa. american journal of physical anthropology, 102, 141-146. july, r.w. (1998). a history of the african people. fifth ed. long grove, illinois: waveland press inc. krige, j.d., & krige, e.j. (1954). the lovedu of the transvaal. in c.d. forde (ed.), african worlds: studies in the cosmological ideas and social values of african peoples (pp. 5-82). london: oxford university press. larsen, c.s. (1997). bioarchaeology: interpreting behavior from the human skeleton. cambridge: cambridge university press. larsen, c.s., shavit, r., & griffin, m.c. (1991). dental caries evidence for dietary change: an archaeological context. in m.a. kelley & c.s. larsen (eds.), advances in dental anthropology (pp. 179-202). new york: wiley-liss, inc. lingstrom, p., holm, j., birkhed, d., & bjorck, i. (1989). effects of variously processed starch on ph of human dental plaque. scandinavian journal of dental research, 97, 92-400. lukacs, j.r. (1992). dental paleopathology and agricultural intensification in south asia: new evidence from bronze age harappa. american journal of physical anthropology, 87, 133-150. lukacs ,j.r. (1996). sex differences in dental caries rates with the origin of agriculture in south asia. current anthropology, 37, 147-153. lukacs, j.r. (2008). fertility and agriculture accentuate sex differences in dental caries rates. current anthropology, 46, 901-914. lukacs, j.r., & thompson, l. (2008). dental caries prevalence by sex in prehistory: magnitude and meaning. in j.d. irish & g.c. nelson (eds.), technique and application in dental anthropology (pp 136-177). cambridge: cambridge university press. mackeown, j., cleaton-jones, p., & hargreares, j. (1995). energy intake, dental caries and periodontal disease in 11-year-old black children in two regions of southern africa: kwazulu and namibia. community dentistry and oral epidemiology, 23, 182-186. morris, a.g., thackeray, a.i., & thackeray, j.f. (1987). late holocene human skeletal remains from snuifklip, near vleesbaai, southern cape. the south african archaeological bulletin, 42, 153160. mulder, m.b. (1992). demography of pastoralists: preliminary data of the datoga of tanzania. human ecology, 20, 383-405. mundorff-shrestha, s.a., featherstone, j.d.b., eisenberg, a.d., cowles, e., curzon, m.e.j., espeland, m.a., & shields, c.p. (1994). cariogenic potential of foods: ii relationship of food composition, plaque microbial counts, and salivary parameters to caries in the rat model. caries research, 28,106-115. newbrun, e. (1982). sugar and dental caries: a review of human studies. science, 217, 418-423. ohinata, f., & steyn, m. (2001). report on human skeletal remains from a later iron age site at simunye (swaziland). the south african archaeological bulletin, 56, 57-61. okazaki, k., pei-ying, t., & kuo-shyan, l. (2013). sex difference in oral disease of millet agriculturalists from the take-vatan lineage of the recent banun tribe of taiwan. anthropological science, 121, 105-113. pistorius, j.c.c., steyn, m,. & nienaber, w.c. (2002). two burials at malle, a late iron age settlement in the bankeveld in the north-west province. the south african archaeological bulletin, 57, 55-63. reader, j. (1997). africa: a biography of the continent africa. new york: vintage books a division of random house, inc. scherer, a.k., wright, l.e., & yoder, c.j. (2007). bioarchaeological evidence for social and temporal differences in diet at pidras negras, guatemala. latin american antiquity, 18, 85-104. sealy, j.c., patrick, m.k., morris, a.g., & alder, d. (1992). diet and dental caries among late stone age inhabitants of cape province, south africa. american journal of physical anthropology, 88, 123 -134. shaw, j.c.m. (1931). the teeth, the bony palate and the mandible in bantu races of south africa. london: john bale, sons and danielsson, limited. skinner, e.p. (1973). west african economic systems. in e.p. skinner (ed.), peoples and cultures of africa: an anthropological reader (pp. 205-210). 29 dental anthropology 2019 │ volume 32 │ issue 02 garden city, new york: natural history press. solanki, g., myburgh, n., & moola, m.h. (1991). dental caries in black preschool children in cape town. community dentistry and oral epidemiology, 19, 178-179. steyn, m. (2003). a comparison between preand post-colonial health in northern parts of south africa, a preliminary study. world archaeology, 35, 276-288. steyn, m., miller, s., nienaber, w.c., & loots, m. (1998). late iron age gold burials from thulamela (pafuri region, kruger national park). the south african archaeological bulletin, 53, 7385. turner, c.g. (1979). dental anthropological indications of agriculture among the jomon people of central japan. american journal of physical anthropology, 51, 619-636. walker, p.l., & erlandson, j.m. (1986.) dental evidence for prehistoric dietary change on the northern channel islands, california. american antiquity, 5, 375-383. zeleza, t. (1997). a modern economic history of africa: the nineteenth century. v. 1. nairobi: east african educational publishers ltd. casserly et al. 2014.2 5 dental anthropology 2014 │ volume 27 │ issues 01 and 02 determining onset of significant facial pathology using dental wear and microwear texture analysis: a case study from the middle archaic (~5,500 bp) of indiana. anna casserly 1 , rebecca van sessen 2 , christopher schmidt 3 1department of anthropology, university of kentucky, lexington, kentucky 40506 2department of sociology and anthropology, indiana university– northwest, gary, indiana 46408 3department of anthropology, university of indianapolis, indianapolis, indiana 46227 burial 54 (b. 54) is a young adult female from meyer site (12sp1082), a late middle archaic mortuary in southern indiana. she presents considerable evidence of a pathological condition, with the cranio-facial bones being the most impacted (figure 1). notably for this study, the anterior maxillary alveolar margin is completely resorbed, resulting in antemortem loss of the anterior dentition from the right lateral incisor to the left first premolar. the mandible indicates major changes to the alveolar region as well; the bone appears to have been weakened to the point of collapsing under the dentition, causing the lower anterior teeth to jut forward at a near 90° angle to their natural position. in addition, the right body of the mandible was the site of a severe lytic lesion measuring at least 39 mm in length. the right lower molars were present at recovery, indicating that they were held within the soft-tissue. together, these conditions were determined to be the result of a treponemal infection (casserly 2013). all of the teeth show some level of macrowear; caries are absent. the only teeth shed antemortem are those of the anterior maxilla mentioned already. the teeth are morphologically similar to those of other people in the cemetery and there are no obvious defects in dental hard tissue quantity or quality. dental macrowear and microwear the objective of the macrowear study was to determine when the bones supporting the dentition started to fail and move the teeth out of their normal anatomical orientations. to accomplish this, the dental macrowear was documented and compared to others from the cemetery in order to determine the approximate age of the individual at the time when the incisors no longer came into contact. the molars were similarly analysed to determine if the point of their disuse corresponded to that of the incisors. the dental microwear texture analysis (dmta) was undertaken to determine the similarity of b. 54’s diet to others from the site in order to determine if she was able to consume typical foods up until the point when she finally succumbed to the disease. methods we scored dental macrowear by direct observation following guidelines described by smith (1984) for the anterior teeth and scott (1979) for the abstract paleopathologists face complicated presentations of osteological conditions that accrued over a considerable period of illhealth. determining the relative sequence of symptoms and how long the individual lived with them is critical to understanding disease onset and progression in the body and may help to identify a specific disease. this paper describes an atypical presentation of the dentition associated with a 5,000-year-old case of treponemal disease. this circumstance led to a cessation of macrowear, which allowed for an estimation of the age when the jaw began to profoundly deform. this paper also summarizes molar microwear texture analysis (dmta) that was employed in order to determine if the diet of the victim prior to death was consistent with other people from the site. correspondence to: anna casserly, dept. of anthropology, university of kentucky, 211 lafferty hall, 150 patterson dr., lexington, ky, 40506-0027 email: acasserly@gmail.com telephone:(859) 257-2710 keywords: treponemal disease, paleopathology, macrowear 6 facial pathology and dental wear dental anthropology 2014 │ volume 27 │ issues 01 and 02 molars. dmta followed guidelines described by scott et al. (2006). molars of seven meyer individuals, including the lower left m2 from b. 54 were replicated with high resolution polyvinylsiloxane impression material and cast with an epoxy-resin. areas of phase ii occlusal facets that were approximately 242.38 x 181.18 μm were viewed with a white light confocal profiler (wlcp) at 100x. analysis of data clouds was conducted via scale sensitive fractal analysis software (sfrax® and toothfrax®), which calculates a number of topographic variables including surface complexity (roughnesss) and anisotropy (similarity of feature orientations). in general, hunter-gatherers (like the population from which b.54 originated) tend to have rough surfaces and moderate anisotropy due to their poorly processed and diverse diets. results burial 54 had anterior tooth wear scores that were in the stage 3 to 4 range. compared to others in her cemetery, the only people with similar anterior wear were two 12 to 14 year-olds. her left first molar scored 31 in the scott’s (1979) system and the right first molar scored a 32. thus, her molars were worn to nearly identical levels on both sides of her mouth. only left side molars were suitable for dmta; the right molars had a thin veneer of occlusal calculus that obscured the surface from view. the means texture values for the meyer site were 1.276 for complexity and 0.002 for anisotropy. the dmta values for burial 54 were 0.847 for complexity and 0.002 for anisotropy. discussion the maxillary condition that b. 54 presents is similar to the handful of other individuals from the middle archaic to also have been diagnosed with treponematosis. snow (1948) describes a young adult male from indian knoll (b. 490) with maxillary resorption that is much like that of b. 54. but that burial does not have the anterior tilt to the mandibular dentition and there is no discussion of a mandibular lytic lesion. in fact, of the four or five possible to likely cases of treponemal disease at indian knoll, none have the mandibular involvement seen in b. 54. it may be that b. 54 has a unique manifestation of treponematosis, or it may be that she actually has more than one condition and that either the lytic lesion, the anterior tilt of the mandibular teeth, or both are related to separate maladies. burial 54’s macrowear scores indicate that she began to lose normal maxillary and mandibular incisal contact in her adolescence perhaps around the time she entered puberty. thus, the condition, or conditions, she had were chronic and she endured them for what was probably a decade or more. her molar macrowear indicates that she maintained a typical diet for most of her life, although the occlusal calculus on the right side molars indicates that those teeth were no longer being used at the end of her life. individual complexity anisotropy burial 54 .8477 .0016 surface mand. a 1.4071 .0036 burial 42 .6905 .0007 burial 46 .9854 .0023 burial 104 2.4398 .0037 burial 109 1.14156 .0009 burial 111 .9912 .0079 fig. 1. (a) left view of mandible showing impact on anterior dentition (b) facial destruction of burial 54. note the maxillary resorption, nasal aperture reduction, and antemortem fracture of left frontal process of maxilla. table 1. dental microwear texture analysis scores for meyer site (a) (b) 7 facial pathology and dental wear dental anthropology 2014 │ volume 27 │ issues 01 and 02 in fact the right side molar enamel is pitted microscopically (which is visible in areas that were not covered with calculus). it is possible the pitting is the result of an acidic oral environment, which may be the result of abnormal saliva secretion or pus, which can have a ph around 6 (nekoofor et al., 2009). microscopic pitting was not found on the leftside molars. as a whole, the meyer site has a dmta complexity value that is very low for a foraging population indicating that the meyer diet likely had a high meat component. burial 54’s microwear values are low even for the meyer site, but they are not the lowest in the population; that distinction is held by a 12-year-old boy who was killed and decapitated. dental texture reflects the last few weeks of one’s life, so it appears that her diet was comparable to other people in her population even if only her left side dentition was in use. it is possible that softer foods became more dominant toward the end, but in general her microwear does not indicate a wholesale change her diet at any point before she died. figure 2 shows a bivariate scatterplot of complexity and anisotropy for the meyer sample. conclusion this study demonstrates the value of dental anthropology in general and macrowear and microwear in particular to help reconstruct the circumstances of a particularly devastating disease condition. the dental data informed us on the age of onset for certain manifestations of the condition as well as the impact the condition had on the victim’s diet. moreover, it aided in the determination of the duration of the condition, which is important for those attempting to better understand the progression of diseases like treponematosis among ancient people. it is hoped that others will consider microwear and macrowear as tools to assist with their diagnoses and analyses in paleopathology. literature cited casserly ac. 2013. infectious disease at the meyer site. ms thesis. university of indianapolis, indianapolis, in. bader at. 2010. evidence of ritualized mortuary behavior at the meyer site: an inadvertent discovery in spencer county, indiana. indiana archaeology. 5:10-49. frazer l. 2011. dental microwear texture analysis of early/middle woodland and mississippian populations from indiana. ms thesis. university of indianapolis, indianapolis, in. krueger kl, scott, jr, kay, rf, ungar, ps. 2008. technical note: dental microwear textures of “phase i” and “phase ii” facets. am j phys anthropol 137:485-490. maier w, schneck, g. 1982. functional morphology of hominoid dentitions. j hum evol 11:693-696. nekoofar mh, namazikhah ms, sheykhresae ms, mohammadi mm, kazemi a, aseeley z, dummer pm. 2009. ph of pus collected from periapical abscesses. int endod j. 42:534-538. schmidt cw, lockhart ra, newman c, serrano a, zolnierz m, bader at, plunkett ja. 2010. skeletal evidence of cultural variation: mutilation related to warfare and mortuary treatment. in: auerbach bm , ed. hu man variation in the americas: the integration of ar chaeology and biological anthropology, occasional paper no. 38. carbondale il: center for archaeological investigations, pp. 215-237. schmidt cw, chiu lw, frazer l, barrett c, mahoney p. 2011. dental microwear texture analysis of natufian hunter-gatherers and neolithic farmers from northern israel. am j phys anthropol suppl 51: 265. scott ec. 1979. dental wear scoring technique. am j pys anthropol 51:213-218. scott rs, ungar, ps, bergstrom ts, brown ca, childs be, teaford, mf, walker a. 2006. dental microwear texture analysis: technical considerations. j hum evol 51: 339-349. smith bh. 1984. patterns of molar wear in huntergatherers and agriculturalists. am j phys anthropol 63:39-56. snow ce, webb ws, haag wg. 1948. indian knoll skeletons of site oh 2, ohio county, kentucky. university of kentucky, dept. of anthropology. teaford mf, lytle jd. 1996. brief communication: dietinduced changes in rates of human tooth microwear: a case study involving stone-ground maize. am j phys anthropol 100:143-147. fig. 2. bivariate scatterplot of complexity and anisotropy. 3 dental anthropology 2019 │ volume 32 │ issue 02 outlining a definition of oral health within the study of human skeletal remains marin a. pilloud 1* and james p. fancher 2 1 department of anthropology, university of nevada, reno 2 department of anthropology, texas state university, san marcos recently the concept of “health” has been criticized in bioarchaeology (e.g., reitsema & mcilvaine, 2014). defining health in past populations, or even among the recently deceased, can be difficult if not impossible as this concept incorporates somewhat unknowable factors about lifestyle and well-being. in response, the term “stress” was incorporated into research, which shifted the focus to conditions of disease or growth disruption. yet, the etiology and interpretation of these markers of stress may not fully capture the experienced life of people in the past. for example, a study based on data from the mexico family life survey found that individuals with anemia were of various socioeconomic statuses and generally did not report being in poor health (piperata et al., 2014). as skeletal signs of anemia are generally used in bioarchaeology as indicators of stress, this study of living individuals has highlighted the actual role of anemia in the lives of people currently experiencing it. based on recent critiques, the incorporation of stress was cited as merely being a replacement for “poor health”, while still failing to address the issues inherent in interpreting the levels of health and stress in past populations. these critiques about quantifying general health and stress in bioarchaeology can be extended to the concept of oral health. a term that has been used in various contexts within the bioarchaeological literature to describe numerous conditions of the teeth and their surrounding bony structures. despite its common use, there is currently no consensus on what should constitute oral health within the bioarchaeological record, and multiple indicators of stress, growth disruption, infection, oral pathology, and non-specific disease may be included. a more comprehensive discussion of oral health within the bioarchaeological record is warranted given inconsistencies in discussion of oral conditions and advances in the clinical literature. in 2014, the american dental association (ada) house of delegates adopted the following definition of oral health as “a functional, structural, aesthetic, physiologic and psychosocial state of well-being… essential to an individual’s general health and quality of life” (http://www.ada.org/ en/about-the-ada/ada-positions-policies-andstatements/ada-policy-definition-of-oral-health). in 2016, the world dental federation (fdi, once called the fédération dentaire internationale) adopted a new definition of oral health that echoes the sentiment of the ada in that oral health is much more than the mere absence of disease. the fdi defines oral health as “the ability to speak, smile, smell, taste, touch, chew, swallow, and convey a range of emotions through facial expressions with confidence and without pain, discomfort, and abstract the term oral health is regularly used in bioarchaeological research to discuss a myriad of pathological conditions of the oral cavity. however, there is very little consensus on what conditions should be included in such a study, and some of the conditions are at odds with those in the clinical literature. in this manuscript, we outline the clinical definition of oral health and develop a strategy in which bioarchaeology can address this type of research. we argue that the terms dental disease and/or pathological conditions of the oral cavity should be used in lieu of oral health. various conditions that can be included in such research are outlined. finally, definitions, clinical etiologies, and recording schema for these conditions are discussed as relevant to bioarchaeological studies. *correspondence to: marin a. pilloud department of anthropology university of nevada, reno reno, nv 89557 mpilloud@unr.edu keywords: periodontal disease, dental caries, hypercementosis, periapical lesions, calculus, antemortem tooth loss, linear enamel hypoplasia 4 dental anthropology 2019 │ volume 32 │ issue 02 disease of the craniofacial complex” (glick et al., 2016:916). this work further emphasizes the interaction of disease status, physiological function, and psycho-social function along with determining and moderating factors that influence overall oral health (glick et al., 2016). from a research perspective, and in a clinical setting, it is critical to understand treatment outcomes and levels of oral health, as poor oral health can have further health and social implications. in recent clinical literature poor oral health has been linked to type 2 diabetes (leite et al., 2013), obesity (östberg et al., 2012), and eating disorders (johansson et al., 2012). further, oral health has been related to school performance (abanto et al., 2011; jackson et al., 2011), quality of life, selfesteem (bennadi & reddy, 2013; gerritsen et al., 2010), and depression (okoro et al., 2012). the concept of oral health-related quality of life (ohrqol) has grown over the last decade and is being recognized as a critical part of dental research and clinical dental practices (sischo & broder, 2011). the ohrqol is typically studied through questionnaires and serves as a means to quantify outcomes to better evaluate treatment in a clinical setting (bennadi & reddy, 2013). the definitions proposed by the ada and fdi as well as the study of ohrqol, raise questions about how bioarchaeologists currently use the term oral health, as it is not possible to understand the “psychosocial well-being” of past populations based only on the archaeological record. further, the clinical research on oral health shows a disconnect with how the term is being used in bioarchaeological research. this paper proposes to address inconsistencies and misconceptions in studies of oral health on skeletal remains. we begin with a review of the current trends in the use of the term and end with a proposed outline of how the term can be used in research on skeletal remains. current use of oral/dental health while the clinical definition of oral health includes conditions of the oral cavity that are detrimental to one’s general quality of life, within bioarchaeological research this definition can vary widely. this variation is illustrated in a survey of articles published in the american journal of physical anthropology, international journal of osteoarchaeology, and the international journal of paleopathology between 1977 and 2018. those articles that use the term “dental health” or “oral health” in the title or abstract (n=44) were searched to identify trends in the use of this term. two of the articles that were recovered in the search were later found to not be related to oral health and were removed from further discussion. in these articles, oral health was quantified through various skeletal indicators to include: periodontal disease, dental caries/carious lesions, linear enamel hypoplasia, crown variation, morphology, dental/occlusal wear, calculus, enamel hypoplasia, periapical defect/lesion/granuloma/ abscess, antemortem tooth loss, cleft palate, alveolar defects/lesions, chipping, dental tilting, hypercementosis, dens in dens, agenesis, and antemortem tooth loss. a word cloud was created to highlight the frequency of each type of skeletal indicator (figure 1). by far the most commonly investigated conditions were dental caries, antemortem tooth loss, and abscesses. within this body of literature there is little consensus on what factors should be studied as part of oral health and may also employ varying definitions of these pathological conditions. however, these research foci are generally in line with the world health organization (who) definitions of dental disease, which include “dental cavities, periodontal (gum) disease, oral cancer, oral infectious diseases, trauma from injuries, and hereditary lesions” (http://www.who.int/mediacentre/ factsheets/fs318/en/). while these dental diseases may be relatively straightforward to diagnose in a clinical setting with a well-known patient history and clinical records, similar diagnoses in archaeological populations may be impossible to assess. we therefore dedicate the following section to outlining factors that can be used in defining diseases of the oral cavity in a bioarchaeological setting. proposed use we propose that based on recent critiques of the figure 1. word cloud highlighting use of terms in research on “oral/dental health”. 5 dental anthropology 2019 │ volume 32 │ issue 02 use of the term health, conditions of the oral cavity be termed dental disease or pathological conditions of the oral cavity. these terms shift the focus from the unknowable aspects of health (i.e., psychosocial well-being) to conditions that can be identified in the maxilla, mandible, and teeth with known etiologies. below we outline which conditions can be used as part of this definition, conditions which are less applicable, and those that should not be included in studies of this nature. conditions to include as dental disease/ pathological conditions of the oral cavity: dental caries is a disease process characterized by dental hard tissue destruction of tooth enamel and dentin due to the bacterial fermentation of consumed carbohydrates. there can be many contributors to dental caries, to include diet, tooth morphology, calculus, age, sex, microbiology, and periodontal disease (fakhruddin et al., 2018; featherstone, 2008; larsen, 2015; young et al., 2015). a recent study of the human oral microbiome found that the progression of dental caries was related to a multiple bacterial species, not just streptococcus mutans, as was previously thought. further, individuals without carious lesions exhibited the presence of various other bacteria (e.g., genera of aggregatibacter and rothia) that were found to impede the development of cariogenic bacteria (beldaferre et al., 2012). in the clinical literature, much work has focused on the prevention of dental caries and increasing outcomes for patients. a center for disease control and prevention study on the presence of dental caries in the united states from 2005-2008 found that 75% of individuals had at least one dental restoration, and that 20% had untreated dental caries. untreated dental caries differed significantly across socioeconomic status; although, younger individuals showed more equity in terms of dental restoration presence (dye et al., 2012). these patterns are in line with recent studies in canada and the united states that found a decline in socioeconomic inequalities in terms of oral health (bernabé & marcenes, 2011; elani et al., 2012). within bioarchaeological research, patterns in dental caries prevalence speak to disease loads and changing diets. the presence of carious lesions is also age dependent and will manifest differently in different teeth. there are various models for scoring dental caries in bioarchaeological research. in a clinical setting, rates of carious lesions are recorded using the dmft method. in which the total number of diseased (d), missing due to disease (m), and filled teeth (f), is divided by the total number of teeth (t). this system would clearly have limited utility in bioarchaeology due to the lack of filled teeth, teeth missing post-mortem, and the inability to determine the cause of antemortem tooth loss (waldron, 2009). for skeletal remains, the moulage system could be employed, which is a series of 85 plaster models that illustrate varying degrees of carious decay in different locations (hillson, 2001). however, these plaques were not made widely available outside of scandinavia, and only a few photographs are available in published manuscripts (lindström, 1940; rönnholm et al., 1951), which makes their broad use impractical. hillson (2001) proposed an alternate method for recording dental caries in which efforts are made to separate data in terms of tooth type, age cohort, sex, and lesion type and location. such an approach can account for differential preservation of tooth types and age groups – both of which have an overall effect on dental caries prevalence calculations. while the method proposed by hillson (2001) is by far the most nuanced and accounts for a range of biological variation, the most commonly employed method of dental caries recordation is that outlined in buikstra and ubelaker (1994). this method relies on a visual inspection of the dentition with recording of dental caries by tooth type and surfaces affected. periodontal disease is actually a cluster of inflammatory diseases that affect the periodontium (langlais et al., 2017; lindhe & lang, 2015). clinically it is especially noted by the inflammatory status of gingiva and other soft tissues. the diseases are generally chronic and slow progressing in nature; although, more aggressive and acute forms do exist. the primary cause is a complex community of microbes that form a biofilm on tooth surfaces and interact with the host response systems to create an inflammatory response. there are many contributing factors that include local tooth anatomy, virulence of the biofilm, and systemic conditions that modify the host response. there are also various biological, social, and behavioral risk factors, which include: socioeconomic status, tobacco use, hormones, stress, excessive alcohol consumption, diabetes, obesity, osteoporosis, root abnormalities, enamel pearls, impacted third molars, and trauma, among many others (jin et al., 2011). the who estimates that between 5 and 20% of adults globally have severe periodontitis (jin et al., 2011). periodontal disease remains a major cause of tooth loss in both developed and developing countries 6 dental anthropology 2019 │ volume 32 │ issue 02 (pihlström et al., 2005). disease limited to the gingiva often does not cause attachment loss and is usually reversible. disease that affects the deeper structures of the periodontium lead to irreversible loss of connective tissue attachment and bone loss. clinically, diagnosis is made based on a combination of measurable factors including pocket depth, clinical attachment loss, anatomical variations, tooth mobility, quantity and position of dental calculus, radiographic changes, and quantity of inflammation. the only factors that may reliably survive to the postmortem or bioarchaeological cases are quantity and position of dental calculus, attachment loss, and radiographic changes. a combination of these data is needed to assess the periodontal status of osseous specimens. much evidence is currently available that links active periodontitis with numerous acute and chronic systemic diseases, including cardiovascular diseases, diabetes, pulmonary diseases, a cerebrovascular diseases (albandar et al., 2018; jepsen et al., 2018; gerry j. linden & herzberg, 2013; gerard j. linden et al., 2013) there are multiple methods to score periodontal disease. in an epidemiological setting periodontal disease may be recorded using the community periodontal index of treatment needs (cpitn), which requires a special probe to document the status of disease and treatment needs (ainamo et al., 1982). (comment: in fact, this system is somewhat flawed and not often used currently, but there is a long history in the literature). as there is no soft tissue in the bioarchaeological record, karn et al. (1984) described a series of deformities of the alveolar process that include crater, moat, ramp, and plane to describe the disease process. nearly a decade later, kerr (1991) proposed an alternate scoring system in which the top of the interdental wall was described as flat/curved, porous, or with breakdown of the contour. most recently, waldron (2009) suggested the presence of periodontal disease should be recorded in individuals with 3 mm or greater distance between the cemento-enamel junction (cej) and the alveolar crest (ac) and recommended that the distance be documented with a periodontal probe. this is the method that most closely approximates the clinical gold standard for measuring the clinical attachment loss associated with periodontal disease, which is the diagnostic basis for defining periodontitis in humans (eke et al., 2012; holtfreter et al., 2015; papapanou et al., 2018). however, when measuring skeletal remains it is also necessary to consider that the connective tissue component of the periodontal attachment apparatus is missing, and a 1mm subtraction from the measured distance from the cej to the ac is necessary to allow for this missing portion of the biological width of tissue attachment (gargiulo et al., 1961). the epidemiological threshold to define early periodontitis for human studies is 3mm of attachment loss (eke et al., 2018), which would be measured as 4mm of distance from the cej to the ac. the clinical threshold that is often used is 2mm of attachment loss (papapanou et al., 2018) (3mm measured from the cej to the ac), which encourages clinicians to diagnose and treat periodontitis at the earliest stages in order to prevent continued irreversible attachment loss. periapical lesions are related to pulpitis when an infection penetrates the pulp cavity. the term periapical lesion is a general term to describe a disturbance of the skeletal tissue around the apex of the tooth that may be related to a granuloma, cyst, or an abscess (figure 2). the general term of ‘periapical lesion’ is preferred as the specific etiology is not possible to diagnose or differentiate without a soft tissue biopsy or a definitive patient history (langlais et al., 2017). even in a clinical setting these distinctions can be difficult to make (stockdale & chandler, 1988), again underscoring the need to keep terminology general in bioarchaeological research. these lesions are merely recorded by location and as present or absent. trauma to the oral cavity could be included under dental disease as it is a disorder of function. further, it could affect the overall well-being of the individual and is included in clinical definitions of oral health. traumata to the oral cavity could include acute trauma such as fractures to the mandifigure 2. example of a periapical lesion of the right maxillary fourth premolar. 7 dental anthropology 2019 │ volume 32 │ issue 02 ble, maxilla, or teeth; or, more long-term trauma such as damages due to bruxism, or issues with the temporomandibular joint. cancers of the oral cavity affecting bone are relatively rare in the bioarchaeological record, but could be included in a general study of oral disease according to the clinical definition of the who. the most common contemporary type of cancer in the oral cavity is squamous cell carcinoma, which may or may not leave a signature on bone. the incidence of oral cancer is also relatively low globally according to the atlas of oral health (beaglehole et al., 2009). oral cancers also tend to have a greater prevalence in older humans, which should be considered in archaeological samples. conditions to potentially include: abscess/granuloma/cyst are terms that should generally be avoided individually as they require soft tissue and/or clinical evidence for a definitive diagnosis. as previously discussed, a more general term such as “periapical lesion” or “a certain anatomical lesion” is nearly always more accurate and includes the undetermined status of the lesion. in general, abscesses are acute lesions with purulent discharge, granulomas are chronic lesions with or without discharge, and cysts are epithelial-lined benign neoplasms. these all may look the same radiographically or as osseous lesions. calculus is a mineralized biofilm on the surface of teeth. the accumulation and composition of calculus can be studied to understand the oral microbiome, or may be measured in relation to other disease parameters (e.g., periodontal disease). however, the exact process of mineralization is not fully understood (warinner et al., 2015). therefore, calculus is thought to be more a product of disease processes rather than the cause of disease, and may be best included as part of pathological conditions of the oral cavity as opposed to dental diseases or can be included in a diagnosis of periodontal disease. in bioarchaeology, the presence of calculus is typically recorded according to the scheme developed by brothwell (1981) in which calculus presence is scored on a scale from 1 to 3 of increasing severity. hypercementosis is the excessive build-up of cementum with unknown etiology (corruccini et al., 1987). although, it has been suggested to be linked to genes, paget’s disease, rheumatoid arthritis, thyroid goiter, acromegaly, and rheumatic fever (mohan, 2014). as the etiology is unknown, it is not appropriate to include it as part of studies focused on dental disease. however, it may be recorded as a dental anomaly or in the differential diagnosis of other, potentially related, conditions. antemortem tooth loss (amtl) should be used cautiously as there are many causes of this condition, some of which may not be related to disease (e.g., dental ablation and trauma). care must also be taken in cases where dental agenesis may be a factor (e.g., third molars, upper lateral incisors, or lower third premolars). it is critical that radiographs are taken in ambiguous cases to ensure impaction is not a factor. although in the clinical literature, tooth loss is largely related to dental disease, predominantly periodontal disease and dental caries (gerritsen et al., 2010). antemortem tooth loss can more definitively be assigned in studies of dental disease in cases where there is large gap, reactive bone, a healed alveolar ridge with a deficient volume of bone, or it is a tooth that is not typically missing due to agenesis, trauma or ablation (figure 3). in cases of uncertainty, antemortem tooth loss should not be recorded. conditions to limit or not include: enamel hypoplasia is a disruption in enamel secretion during dental development (goodman & rose, 1990). these enamel defects can manifest as pits, furrows, or plane defects (hillson & bond, 1997). enamel hypoplastic defects are linked to episodic childhood stress, such as malnutrition and fevers (hillson, 1996). as such, they are an indication of general stress, not specific to the oral cavity, and are therefore not applicable to a study cenfigure 3. example of antemortem tooth loss with reactive bone and a large gap on the right mandible. 8 dental anthropology 2019 │ volume 32 │ issue 02 tered on dental disease. occlusal wear is a reduction in the dental hard tissues related to traumatic injuries to teeth caused by abrasion, attrition, and/or erosion (ibsen & phelan, 2018; langlais et al., 2017). although these injuries may lead to reduced function of the dentition due to loss or alteration of dental hard tissues, the occlusal wear itself is not a disease process, but is the result of either (1) wearing away of tooth structure from a repetitive mechanical habit (abrasion), (2) wearing away of tooth structure due to tooth-tooth contact (attrition), or (3) loss of tooth structure resulting from chemical action not of bacterial origin (erosion). unless the processes or results of occlusal wear can be specifically identified as pathological, such as there is associated pulp exposure with infection, general wear is not an indicator of dental disease. it is likely more related to the time span of life (often expressed as age), consumed foods, the use of teeth as tools, sex, bite force, malocclusion, environmental or salivary factors (dahl et al., 1993). tooth size/morphology/agenesis are all conditions that are considered highly heritable and should be studied as separate conditions. tooth size may be related to non-specific indicators of childhood or maternal stress (pilloud & kenyhercz, 2016), and therefore is not related to studies of dental disease. moreover, there are no good data to show that morphology or dental agenesis are related to stress or a disease process. chipping is related to microtrauma and therefore a reflection of biting force and potentially diet and tool use (scott & winn, 2011). chipping also may be due to blunt force, or an eventual result of wear. unless the chipping leads to pulp exposure and infection, or possibly radiographic signs of secondary dentin formation as a result of the trauma, it is not a disease process on its own. cleft palate is a congenital defect that is also not related to any active disease process, and it should be considered separately. even though it may affect overall function of the oral cavity, there is much variation in expression and severity and due to its relative rarity in the archaeological record, it should be considered independently in studies of pathological conditions of the oral cavity. discussion and conclusions the study of pathological conditions of the oral cavity in the past are an important aspect of archaeological research. these conditions can inform our understanding of diet, disease loads, activity, and genetic composition of past populations. we argue that this research is an important endeavor that is only lacking in a level of clinical standardization and appreciation. measures of dental disease in the archaeological record that can conform to current measures of dental disease will improve the relevance and understanding of disease processes that can be related over the continuum of human history. this manuscript is meant to start the discussion of standardizing research on dental disease with an emphasis on clinical research. this work is not meant to be the definitive word on bioarchaeological research on oral health or dental disease; instead, we hope to generate a discussion on this research and work towards an integrated approach that fully intertwines bioarchaeological research within a clinical reality that embraces the accurate use of terms. acknowledgments we thank all the participants who were part of the original symposium on oral health at the american association of physical anthropology annual meetings in austin, texas in 2018. we also thank the dental anthropology association for sponsoring the symposium from which this paper stems. and, we thank başak boz for reviewing this paper. references abanto, j., carvalho, t. s., mendes, f. m., wanderley, m. t., bönecker, m., & raggio, d. p. 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(2015). standards for reporting chronic periodontitis prevalence and severity in epidemiologic studies. journal of clinical periodontology, 42(5), 407-412. ibsen, o. a. c., & phelan, j. a. (2018). oral pathology for the dental hygienist. st louis, mo: elsevier. jackson, s. l., vann, w. f., jr., kotch, j. b., pahel, b. t., & lee, j. y. (2011). impact of poor oral health on children's school attendance and performance. american journal of public health, 101 (10), 1900-1906. jepsen, s., caton, j. g., albandar, j. m., bissada, n. f., bouchard, p., cortellini, p., demirel, k., sanctis, m., ercoli, c., fan, j., geurs, n. c., hughes, f. j., jin, l., kantarci, a., lalla, e., madianos, p. n., matthews, d., mcguire, m. k., mills, m. p., preshaw, p. m., reynolds, m. a., sculean, a., susin, c., west, n. x., & yama10 dental anthropology 2019 │ volume 32 │ issue 02 zaki, k. 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(1991). prevalence and natural history of periodontal disease in scotland – the mediaeval period (900–1600 a. d.). journal of periodontal research, 26(4), 346-354. langlais, r. p., miller, c. s., & gehrig, j. s. (2017). color atlas of common oral diseases, fifth edition. philadelphia: wolters kluwer. larsen, c. s. (2015). bioarchaeology: interpreting behavior from the human skeleton. cambridge: cambridge university press. leite, r. s., marlow, n. m., fernandes, j. k., & hermayer, k. (2013). oral health and type 2 diabetes. the american journal of the medical sciences, 345(4), 271-273. linden, g. j., & herzberg, m. c. (2013). periodontitis and systemic diseases: a record of discussions of working group 4 of the joint efp/ aap workshop on periodontitis and systemic diseases. journal of periodontology, 84(4-s), s20s23. linden, g. j., lyons, a., & scannapieco, f. a. 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(2012). oral health and obesity indicators. bmc oral health, 12(1), 50. papapanou, p., sanz, m., buduneli, n., dietrich, t., feres, m., fine, d. h., flemmig, t., garcia, r., giannobile, w., graziani, f., greenwell, h., herrera, d., kao, r., kebschull, m., kinane, d., kirkwood, k., kocher, t., kornman, k., kumar, p., loos, b., machtei, e., meng, h., mombelli, a., needleman, i., offenbacher, s., seymour, g., teles, r., & tonetti, m. (2018). periodontitis: consensus report of workgroup 2 of the 2017 world workshop on the classification of periodontal and peri-implant diseases and conditions. journal of periodontology, 89(s1), s173-s182. pihlström, b., michalowicz, b., & johnson, n. (2005). periodontal diseases. lancet infectious diseases, 366, 1809-1820. pilloud, m. a., & kenyhercz, m. w. (2016). dental metrics in biodistance analysis. in m. a. pilloud & j. t. hefner (eds.), biological distance analysis: forensic and bioarchaeological perspectives (pp. 135-155). san diego: academic press. piperata, b. a., hubbe, m., & schmeer, k. k. (2014). intra-population variation in anemia status and its relationship to economic status and self -perceived health in the mexican family life survey: implications for bioarchaeology. american journal of physical anthropology, 155(2), 210220. reitsema, l. j., & mcilvaine, b. k. (2014). reconciling “stress” and “health” in physical anthropology: what can bioarchaeologists learn from the other subdisciplines? american journal of physical anthropology, 155(2), 181-185. rönnholm, e., markén, k.-e., & arwill, t. (1951). record systems for dental caries and other conditions of the teeth and surrounding tissues. odontologisk tidskrift, 59, 34-56. scott, g. r., & winn, j. r. (2011). dental chipping: contrasting patterns of microtrauma in inuit and european populations. international journal of osteoarchaeology, 21(6), 723-731. sischo, l., & broder, h. (2011). oral health-related quality of life: what, why, how, and future implications. journal of dental research, 90(11), 1264-1270. stockdale, c., & chandler, n. (1988). the nature of the periapical lesion—a review of 1108 cases. journal of dentistry, 16(3), 123-129. 11 dental anthropology 2019 │ volume 32 │ issue 02 waldron, t. (2009). paleopathology. cambridge: cambridge university press. warinner, c., speller, c., & collins, m. j. (2015). a new era in palaeomicrobiology: prospects for ancient dental calculus as a long-term record of the human oral microbiome. philosophical transactions of the royal society b, 370(1660), 20130376. young, d. a., nový, b. b., zeller, g. g., hale, r., hart, t. c., truelove, e. l., ekstrand, k. r., featherstone, j. d. b., fontana, m., ismail, a., kuehne, j., longbottom, c., pitts, n., sarrett, d. c., wright, t., mark, a. m., & beltranaguilar, e. (2015). the american dental association caries classification system for clinical practice. the journal of the american dental association, 146(2), 79-86. 12 dental anthropology 2019 │ volume 32 │ issue 02 periodontal health and the lifecourse approach in bioarchaeology alexandra tuggle 1 and james t. watson 2,3* 1 department of anthropology, the ohio state university 2 arizona state museum, university of arizona 3 school of anthropology, university of arizona periodontal tissues historically receive little attention in bioarchaeological research. periodontal ‘health’, however, is essential to maintaining a foundation for attachment, stability, and retention of teeth. the concept of ‘health’ is more than the absence of disease and is therefore problematic among both clinicians and bioarchaeologists (see pilloud and fancher, this issue). mariotti and hefti’s (2015) call for redefinition of periodontal health among clinicians, using a modified wellness model, includes both physical (functional dentition and periodontal attachment stability) and psychosocial (pain and individual well-being) characteristics. the challenge for bioarchaeologists is defining what physical expression/degree within a disease process would begin to affect an individual’s wellbeing. here we therefore apply a lifecourse approach to the measurement of periodontal disease in a prehistoric sample from the american southwest to test the hypothesis that age and sex differences bear the greatest impact on the expression of periodontitis. periodontal disease (pd) is the clinical characterization of destruction of the periodontium—the oral structure containing the teeth, composed of both fibrous (gingival and periodontal ligament) and mineralized (cementum and alveolar bone) tissues. periodontal disease has a multifactorial etiology, but is primarily associated with inflammatory host response resulting from bacterial infection of periodontal tissues. many bacterial species have been associated with the pathogenic colonization of subgingival biofilm (dental plaque) (adriaens, de boever, & loesche, 1988; boutin et al., 2017; socransky & haffajee, 2005) and the periodontal pocket provides an ideal eco-system for these organisms, containing a diverse microbiota of up to 700 prokaryote species (boutin et al., 2017; chen et al., 2010). martelli and colleagues (2017) identify that the progression and severity of pd depends on the aggressiveness of the subgingival abstract healthy periodontal tissues are essential to maintaining attachment, stability, and retention of teeth. the concept of ‘health’ is problematic however and includes both physical and psycho-social characteristics. the challenge for bioarchaeologists is defining what physical expression begins to affect an individual’s well-being. here we apply a lifecourse approach to periodontal tissue health in a prehistoric sample (n = 166) from the american southwest to test the hypothesis that age and sex differences bear the greatest impact on the expression of periodontitis. tooth loss, tooth wear, periodontal depth (cej-ac), and alveolar crest (ac) morphology were recorded at m1. t-tests identify that females exhibit significantly higher values across each variable. in addition, general linear modeling analyses demonstrate that values increased significantly across five age stages (15-20yo, 20-30yo, 30-40yo, 4050yo, 50+yo) with females exhibiting significantly higher values in the fourth and fifth decades of life. results support the hypothesis that periodontal tissue loss differentially affects females across the lifecourse. bacterial infection, chronic gingivitis, and attachment loss cause the physical symptoms of periodontal disease but may not be accompanied by pain or altered functionality. the outcome of the disease process is tooth loss, which can affect functionality and quality of life. periodontal ‘health’ is therefore best interpreted in bioarchaeological samples around the point that attachment loss results in tooth loss and altered functionality. *correspondence to: james t. watson arizona state museum university of arizona po box 210026, tucson, az 85721 watsonjt@email.arizona.edu keywords: periodontal disease, dental anthropology, lifecourse 13 dental anthropology 2019 │ volume 32 │ issue 02 plaque biofilm and individual host immune response, which can be further affected by genetic and epigenetic contexts and environmental factors (i.e., age, sex, smoking, oral hygiene, etc.). today, pd is also correlated with various systemic disorders, including cancer, diabetes, rheumatoid arthritis, cardiovascular diseases, and preterm birth (jepsen et al., 2018; martelli et al., 2017). studies of modern and prehistoric patterns of periodontal disease demonstrate that men generally have a higher prevalence than women (dewitte, 2012; shiau & reynolds, 2010; wasterlain et al., 2011). dewitte (2012) proposes that this is likely due to immuno-buffering from estrogen among women (klein and huber, 2010). but there is other clinical evidence to suggest that hormonal fluctuations, particularly associated with pregnancy, may have adverse effects on periodontal health (carrillo -de-albornoz et al., 2010; laine, 2002; lukacs and largaespada, 2006; silk et al., 2008; wu, chen, & jian, 2015). during pregnancy, production of estrogens and progesterone is increased. estrogen levels rise to over 100 times more than pre-pregnancy levels, with progesterone levels surpassing this even more. during labor, hormone concentrations drop, reaching their pre-pregnancy levels within 23 days after delivery (laine, 2002). after the second trimester, the placenta begins regulating hormone production to maintain the pregnancy, including maintenance of the endometrium, preparation for lactation, increase in basal metabolic rate, and regulation of the immune system. the affiliated vascularization of bodily tissues often causes the gingiva to become inflamed and retain fluid, resulting in pregnancy gingivitis and edema (bobetsis et al., 2006; laine, 2002). while pregnancy does not actually cause gingivitis or periodontitis, the hormonal activity in gingival tissues can exacerbate pre-existing periodontal disease. with increased gingival inflammation and edema, the periodontium can become weakened (laine, 2002; silk et al., 2008). especially in the presence of accumulated plaque and calculus, the gingiva can become detached from the tooth exposing the periodontium (coventry et al., 2000). when bacteria infiltrate the weakened periodontium, their toxins activate a chronic inflammatory response, causing the ligaments and bone supporting the teeth to break down (silk et al., 2008). current research has identified some specific pathophysiology that may contribute to pd associated with hormonal activity during pregnancy. pregnant women experience pronounced fluctuations in the sex hormone estrogen. estrogen acts as a ligand for estrogen receptor ß (erß), which plays an important role in periodontal ligament cell function and proliferation (jönsson et al., 2004; liang et al., 2008; mamalis et al., 2011; wattanaroonwong et al., 2011). the periodontal ligament (pdl) is a connective tissue that bonds the cementum of the tooth to the alveolar bone. collagen-producing pdl cells restore mineralized tissue and thus are essential in maintaining the structural and functional integrity of the periodontium. human pdl cells have receptors for estrogen (erß), which in turn has an inhibitory effect on bone-resorbing osteoclast formation in the periodontium (wattanaroonwong et al., 2011). fluctuations in estrogen levels during pregnancy may affect subsequent pdl cell proliferation and consequently periodontal integrity (mamalis et al., 2011). changes in progesterone levels associated with pregnancy can make the subgingival microbiota significantly more anaerobic (kornman & loesche, 1982; paropkari et al., 2016). less well explored is how salivary sex hormones affect the supragingival microbiota, which also experiences an ecological shift in association with pregnancy. recently, lin et al. (2018) explored the bacterial diversity and ecological shifts in the supragingival plaques of pregnant women and observed it is highly correlated with the subgingival microbiota and may equally contribute to oral dysbiosis during pregnancy. lin et al. (2018) posited that consistent with surges in progesterone and estradiol during the third trimester, pregnancy constructs an environment conducive to some bacterial strains including members of the neisseria and poryphromonas genera. progesterone may also downregulate il-6 production by gingival fibroblasts, resulting in gingival inflammation and bacterial proliferation (lapp et al., 1995). other hormones associated with significant fluctuations during pregnancy have also been explored as possible contributors to pd in women. parathyroid hormone, a calcitropic hormone responsible for calcium metabolism, decreases in early pregnancy. this is followed by a spike in the first trimester, a decline at the middle, and another rise towards the end of a pregnancy (hameedi, 2017). osteocalcin, an osteoblastic hormone, mirrors parathyroid hormone fluctuations throughout pregnancy with corresponding effects on boneformation processes (seki et al., 1991). progesterone levels also are negatively associated with calcium levels in pregnant women (hameedi, 2017). 14 dental anthropology 2019 │ volume 32 │ issue 02 fertility in prehistoric agricultural communities the holocene is characterized in part by the substantial increase in human populations that occurred in a relatively small amount of time, markedly in areas that adopted agriculture (larsen, 1995). although the transition from foraging to farming is generally characterized by a decline in overall health (including a decline in skeletal robusticity and dental health), the archaeological record displays evidence of a "neolithic demographic transition" (ndt), wherein populations expanded in most agricultural communities throughout the world (bocquet-appel, 2002; bocquet-appel & dubouloz, 2004; bocquet-appel & naji, 2006). while population growth is apparent, sedentary settlement is also commonly associated with a reduction in mean age-at-death and high prevalence of skeletal lesions, often ascribed to nutritional deficiencies or infectious disease (cohen & armelagos, 1984). a decline in health and mean age-at-death coupled with an increase in population seems paradoxical, but many contend that this trend indicates an increase in fertility rather than an increase in mortality due to poor general health (wood, 1992). in addition, the greater prevalence of skeletal lesions evidenced in agricultural samples could alternatively reflect enhanced resilience to illness and stress (wood, 1992). multiple causes for an increase in fertility among sedentary agriculturalists have been proposed. cultivation of domestic crops such as maize in the new world would not only increase the carrying capacity of the environment, but also result in lifestyle shifts leading to increased fertility (lukacs, 2008). more dependable, higher calorie food supplies, a reduction in workload, and more readily available weaning foods would both increase the energy available to mothers and decrease the necessary weaning time. fecundity (the biological potential for childbearing) can be sensitive to energetic stress, and even moderate energetic stress appears to suppress ovarian hormone levels (ellison et al., 2012). with decreased mobility associated with an agricultural lifestyle and a carbohydrate-based, calorie-dense diet, women would likely be under less energetic stress and thus more fecund. a shorter weaning period may also influence fertility by a reduction in interbirth intervals. lactation suppresses ovulation and often has a contraceptive effect due to the results of lactational amenorrhea (kennedy & visness, 1992; who, 1999). however, variation in the contraceptive effect seems to be related to maternal energetic state. research shows that maternal physiology acts to lower the chance of another conception when energetic investment in the current child is still high. lactation is energetically expensive, and if the weaning age is decreased due to supplementation of weaning foods, the mother may return to a fecund state more quickly (ellison, bogin, & o'rourke, 2012). ethnographic comparisons with modern foraging societies show that they generally exhibit longer interbirth intervals (generally 3-4 years) and decreased fertility due to longer breastfeeding periods, higher mobility/activity level, and seasonal weight fluctuations with resource availability (eshed et al., 2004; hitchcock, 1982; howell, 1979). in addition, higher rates of infant mortality (as experienced by early agricultural populations) can increase fertility by returning a mother to a fecund state after the loss of a breastfeeding child (ellison, bogin, & o'rourke, 2012). given the complex interplay between reproductive hormones and the reproductive burden associated with burgeoning population growth among prehistoric agricultural groups, the cumulative effects of high fertility rates would differential affect women in these prehistoric communities. we therefore suggest that age and sex differences have the greatest impact on the expression of periodontal disease, which may be a function of high fertility. here we apply a lifecourse approach to the measurement of periodontal disease in a prehistoric sample from the american southwest to test this hypothesis. materials and methods the samples analyzed in this study were recovered from a series of archaeological sites associated with the mogollon archaeological culture (fig. 1). the mogollon archaeological culture is associated with ancestral puebloan occupation of the rugged intermontane region of east-central arizona and westcentral new mexico (reid & whittlesey, 1997). the mogollon area is physiographically diverse with low valleys containing desert and grassland ecosystems and high elevations (~6,000 feet) characterized by large, ponderosa pine forests and juniper/ piñon woodlands (reid, 2006; woodbury, 1961). although agriculture, particularly reliant on maize, was the foundation of their subsistence economy, a variety of local wild resources continued to provide an important role in the diet (reid & whittlesey, 1997; woodbury, 1961). the pueblo period of mogollon development in arizona began around a.d. 1100 with the transition from pit houses to masonry construction and 15 dental anthropology 2019 │ volume 32 │ issue 02 lasted until about a.d. 1400 when the pueblos were abandoned and populations became effectively archaeologically invisible (reid & whittlesey, 1997). this period is characterized by rapid population growth and nucleation into fewer, larger villages. nucleation resulted in denser population concentrations within groups but larger distances between groups (tuggle, 1970). as population densities increased, pueblo residents became more dependent on cultivated crops and relied less on foraging wild resources. sometime around a.d. 1400, as most communities neared the maximum population density that could be supported by available agricultural technologies and exhausted their wild resources, mogollon villages were largely abandoned. environmental pressure was aggravated by several periods of drought, resulting in migration out of the region (reid & whittlesey, 1997; tuggle, 1970). there is also evidence of significant economic and social tensions (reid and whittlesey, 1997). skeletal remains from five mogollon sites were analyzed for evidence of periodontal disease. the sites include point of pines, turkey creek, kinishba, king ruin, and az:w:10:52(asm), which represent a series of large, multi-room pueblos that emerged in the mogollon region with occupations that ranged between a.d. 1225 to 1450 (east, 2008; haury, 1989; lowell, 1991; welch, 2016). together these samples represent a 225-year sequence of population growth, until social collapse, reorganization, migration, and partial abandonment of the mogollon area. based in successful agricultural adaptations, it is likely that a combination of environmental and social stressors led to eventual collapse. the demographic profile, including generally a higher infant mortality fits the curve proposed by bocquet-appel (2002) as representing high fertility populations and therefore make ideal samples to test the relationship between periodontal disease and sex across the lifecourse. the mogollon samples are part of the bioarchaeology collection at the arizona state museum (asm), university of arizona in tucson, arizona. sex and age data were obtained from the arizona state museum human remains database, estimated previously by asm curators using macroscopic aspects of the pelvis and/or cranium for sex (buikstra and ubelaker, 1994), and macroscopic changes in the pubic symphysis (buikstra & ubelaker, 1994) and relative rates of dental attrition (brothwell, 1989) for age. individuals of indeterminate sex or age were excluded from the analysis. table 1 displays the distribution of samples by site, age, and sex. the 166 individuals were separated into five decadal age sets representing the sequence from late juvenile to senescence. we focused our analysis on the first permanent mandibular molar (m1) because periodontal disease differentially affects posterior teeth (kerr, 1989) and the first molar is in occlusion the longest among the posterior teeth, thereby having the greatest potential for the expression of pd over the lifecourse. the remains were analyzed at the asm by james watson and theodora burbank and included 1) an inventory of teeth including antemortem loss, 2) recording occlusal surface wear (wear) according figure 1. map of southwest us/northwest mexico with the mogollon archaeological culture area defined by dashed line, and location of sites plotted (marked by squares). map reproduced with permission from arizona state museum. site sex 15-20 20-30 30-40 40-50 50+ point of pines m 1 9 9 3 1 f 5 12 10 3 0 turkey creek m 2 4 10 13 4 f 2 5 9 11 6 kinishba m 3 5 7 0 1 f 7 4 4 2 0 king ruin m 0 0 0 1 0 f 0 1 1 1 0 az:w:10: 52 m 0 3 3 1 0 f 0 2 0 1 0 table 1. archaeological samples used in analysis 16 dental anthropology 2019 │ volume 32 │ issue 02 to scott (1979), 3) measuring distance of the alveolar crest (ac) from the cemento-enamel junction (cej) on the buccal surface of m1 (cej-ac) with a periodontal probe (hu-friedy unc-15 color-coded periodontal probe), and 4) alveolar crest (ac) morphology according to kerr (1988). independent samples t-tests are used to compare mean values for wear, cej-ac, and ac and a mann-whitney u test to compare frequency of tooth loss between sexes. in addition, general linear modeling analysis (gill, 2001)—with age as the covariate and sex as the grouping factor— compares mean values between sexes across age groups. all statistical procedures were performed using ibm spss statistics for windows, v25.0 (spss inc., chicago, il., usa). results preliminary comparisons by sex identify significant differences in mean values, with females exhibiting higher rates of wear, deeper cej-ac depths, and more compromised alveolar crest morphology (table 2). in addition, the mann-whitney u test indicates that tooth loss was greater for females (mean rank: 76.01) than males (mean rank: 91.55), u= 6537.0, p= .006. comparisons across age groups demonstrate the general age-related progression of periodontal attachment loss that is typical of the general trend in clinical studies (billings et al., 2018; eke et al., 2018). the results of the general linear modeling analysis show similar significant differences in tooth wear, alveolar crest depth, and alveolar crest morphology between males and females across age grades (table 3). figures 2-4 plot the means and 95% confidence intervals of each variable across age groups demonstrating similar patterns over the life course. mean values are similar between males and females in the youngest age cohorts but begin to separate in the fourth and fifth decades of life, only to return to closer values in the final decade (s). in addition to measurable attachment loss of the alveolar crest, tooth loss at m1 was significant. tooth loss is again more pronounced among females compared to males in the middle decades of life; 30-40yo and 40-50 (fig. 5). discussion our results support the hypothesis that periodontal disease can be measured across the lifecourse (using the proxy measurements observed here) and demonstrate that females suffered disproportionately from tooth and periodontal tissue loss. periodontal attachment loss differed over the lifecourse; however, with both sexes experiencing similar (non-significant) periodontal tissue depths and morphology in the early age grades and experiencing significant increases after roughly age 30. males appear to display a steady, age-related decline in periodontal tissue quality that only again approaches higher female levels in the oldest age variable sex n mean s.d. t df sig. wear m 80 3.59 1.17 -4.682 164 <0.001 f 86 4.58 1.53 cej-ac m 80 2.11 1.21 -3.695 164 <0.001 f 86 2.81 1.23 ac m 80 2.09 0.93 -5.656 164 <0.001 f 86 2.94 1.01 variable sex 15-20 20-30 30-40 40-50 50+ f df sig. wear m 3.0 3.0 4.0 4.0 4.0 31.030 2 <0.001 f 3.0 4.0 5.0 5.0 6.0 cej-ac m 1.0 2.0 2.0 2.0 3.0 20.659 2 <0.001 f 2.0 2.0 3.0 3.0 4.0 ac m 2.0 2.0 2.0 2.0 3.0 30.433 2 <0.001 f 2.0 3.0 3.0 3.0 4.0 table 2. results of independent samples t-tests for variables by sex table 3. results for general linear modeling by sex and age groups 17 dental anthropology 2019 │ volume 32 │ issue 02 grade; and this is more related to greater variability in expression among males rather than a final spike in tooth and tissue loss. significant differences between sexes from 30 to 50 years suggests an underlying biological phenomenon negatively affecting women's oral health. we propose that hormonal fluctuations associated with reproduction and higher parity in prehistoric mogollon communities are the cause of disparities in periodontal retreat and tooth loss between sexes. tooth loss specifically can also result from dental caries, pulp exposure from heavy wear, and trauma; but the co-occurring trends observed in the data suggest inter-related processes contributing to tooth loss. it is likely that trends in caries frequency in the sample would mirror those observed in periodontal tissues but is beyond the scope of the current study. tooth wear also appears to have played a role in destabilizing periodontal tissues through continuous eruption in response to heavy tooth wear. yet, tooth wear also increases significantly in the interval from 30 to 50 years where female periodontal health incrementally declines compared to males and is perhaps exacerbated by tooth loss, loss of contact, and malocclusion. clinical and epidemiological research shows that the hormonal fluctuations associated with reproductive physiology play a substantial role in maintaining healthy periodontal tissues (laine, 2002; wu et al., 2015). evidence from ethnographic accounts and the archaeological record suggests a figure 2. mean wear score (from scott, 1979) at m1 plotted by age groups for males and females. error bars represent 95% confidence intervals. figure 3. mean distance (mm) from the cemento-enamel junction on the buccal surface of m1 to the alveolar crest plotted by age groups for males and females. error bars represent 95% confidence intervals. figure 4. mean alveolar crest morphology score (from kerr, 1988) at m1 plotted by age groups for males and females. error bars represent 95% confidence intervals. figure 5. frequency (%) of tooth loss at m1 plotted by age groups for males and females. 18 dental anthropology 2019 │ volume 32 │ issue 02 general pattern of increased fertility with the adoption of agriculture in most areas (bocquet-appel & naji, 2006; eshed et al., 2004). sedentism is associated with lifestyle changes that could critically impact fertility, including increased availability of energy-dense foods, decreased mobility, and shorter interbirth intervals (ellison et al., 2012; lukacs, 2008). a cariogenic diet reliant on maize undoubtedly played a crucial role in the overall decline in oral health observed in prehistoric agricultural populations of the southwest us/northwest mexico. dietary composition and high fertility likely led to an environment in which women experienced exacerbated oral pathology (watson et al., 2009). this study contributes some insights into the oral health of women in prehistoric agricultural communities in arizona. the impact of pregnancy and reproduction has been largely avoided in archaeological literature, in part due to the difficulty associated with its study. while this study barely scratches the surface of the problem, it highlights a need to engage with life history theory and acknowledge the influences of reproductive life history on women's health in archaeological research. although current medical and dental therapy place emphasis on improving the well-being of pregnant women and their unborn children (jared & boggess, 2008; russell & mayberry, 2008; sanz & kornman, 2013), data show that increased parturition is still related to increased tooth loss in a woman’s lifespan (christensen et al., 1998; russell et al., 2008). this trend of increased tooth loss extends across cultural and socio-economic boundaries. it probably is related to the ongoing problem of untreated dental disease, which includes maternal periodontitis (jeffcoat et al., 2001; offenbacher et al., 1996). our results specifically demonstrate that cumulative effects among reproductive-age and post reproductive-age females caused disproportionate tooth and periodontal tissue loss. hormone fluctuations associated with reproductive physiology play a substantial role in maintaining healthy periodontal tissues (wu, chen, & jiang, 2015). bacterial infection, chronic gingivitis and attachment loss cause the physical signs and symptoms of periodontal disease. however, this inflammatory destruction of the periodontium often is not accompanied by pain or altered function until advanced degrees of destruction. the penultimate outcome of the disease process is tooth loss, which can affect functionality and quality of life. periodontal ‘health’ is therefore best interpreted/conceptualized in bioarchaeological samples around the point that attachment loss destabilizes the tooth and results in loss and altered functionality. although still stemming from a ‘diseasefocused’ approach, we consider how functional occlusion plays a significant role in health. in addition, the pain and process involved in tooth loss and removal will significantly impact quality of life, followed by altered functionality and differential wear. this allows bioarchaeologists to relate past people’s physical conditions to modern clinical and epidemiological understandings of health and pathology. acknowledgements we would like to express our gratitude to theo burbank for assisting with data collection on several of the skeletal collections, to marin pilloud and j. p. fancher for their invitation to contribute to the 2018 aapa poster symposium dedicated to “reevaluating the meaning of ‘oral health’ in bioarchaeology”, to marin pilloud for the invitation to contribute to this special issue of dental anthropology, and again to j. p. fancher for extensive comments that led to a much improved manuscript. references adriaens, p.a., de boever, j.a., loesche, w.j. 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(2015). relationship between gingival inflammation and pregnancy. mediators of inflammation, vol. 2015, article id 623427, 11 pages. jones 1996.4 pg18.jpg pg19.jpg blankenship-sefczek 2013.3 15 brief communication: maxillary lateral incisor morphology and uncommon trait expression: a case study from prehistoric paa-ko, new mexico erin c. blankenship-sefczek the ohio state university, columbus, oh 43210 abstract prehistoric american southwest exhibits a high frequency of dental morphological variability. this high variability may be the result of gene flow and subsequent genetic drift occurring in early periods (pre ce 900), though few studies report on dental variability in later periods. morphological traits of the maxillary lateral incisors were analyzed from the pueblo iv site of paa-ko, new mexico (ce 1300-1425) yielding high frequencies of four traits (shovel, double shovel, tuberculum dentale, interruption groove) and uncommon variants (barrel-shovel, triform, pegshaped). lateral incisor morphology is underrepresented in the literature but could be useful in determining population migration and affinity. key words: dental morphology, upper central incisors, discrete dental trait, prehistory, iberian peninsula. dental morphological traits, such as shoveling, tuberculum dentale, and interruption groove, reflect population affinity and movement (scott and turner, 1997). within the new world, the greatest dental morphological variability is found in the prehistoric american southwest (scott et al., 1983; bailey-schmidt, 1995; scott and turner, 1997; mcclelland, 2003; kuba, 2006).this high variability may be a result of migration and genetic drift, as introduction of new genes and subsequent population isolation changes the expression of dental traits (leblanc et al., 2008).mitochondrial dna evidence from the prehistoric southwest region suggests there was migration followed by population isolation in several areas, including the new mexico pueblo region (malhi et al., 2003). archaeological evidence indicates migration into the southwest from surrounding areas prior to the pueblo iv period (ce 900-1500; wilcox and haas, 1994; leblanc, 1999; malhi et al., 2003; leblanc et al., 2008) was likely a response to resource unpredictability caused by warm droughts and high seasonal resource stress (dean, 1996; benson et al., 2007). unfortunately, few bioarchaeological studies dealing with dental morphology in the later pueblo iv period have been produced, limiting our ability to address this pre-contact period of population movement. this study interprets dental morphology of one tooth, the maxillary lateral incisor, from the site of paa-ko, new mexico in order to add to our understanding of southwest dental morphological variability. expressions of discrete dental traits are used to determine biological distance, population movement, and evolutionary trends (turner et al., 1991; scott and turner, 1997; irish and guatellisteinberg, 2003). maxillary lateral incisors, having the highest amount of variation in trait expression of all tooth types, is a key tooth for understanding genetic relationships and population comparisons (turner et al., 1991; bailey-schmidt, 1995; scott and turner, 1997). scott and turner (1997:32) describe categories of discrete trait variation in maxillary lateral incisors, including barrel-shovel, triform, and peg-shaped or conical incisors, which deviate from the more prevalent morphological forms of shovel and tuberculum dentale. studies on dental morphology throughout the prehistoric american southwest reveal higher variability of maxillary lateral incisor trait expression than any other location worldwide, particularly for shovel, barrel shovel, and full expression of tuberculum dentale and its variants (sofaer et al. 1972; lebot and salmon 1977; turner and swindler 1978; kieser and preston 1981; baileycorrespondence to: erin c. blankenship-sefczek the ohio state university department of anthropology 4034 smith laboratory 174 w. 18th ave. columbus, oh 43210 (916) 752-2436 blankenship-sefczek.1@buckeyemail.osu.edu 16 schmidt, 1995; scott and turner 1997; burnett and weets 2001; mcclelland 2003; bollini et al., 2008; leblanc et al., 2008). this study analyzes the frequency of maxillary lateral incisor traits from the prehistoric site of paa-ko, new mexico (ce 13001425), adding to the literature on pueblo iv southwest dental morphology. materials and methods skeletal remains analyzed for this study were recovered from paa-ko, new mexico between 1935 and 1937 as a joint venture of the museum of new mexico, the school of american research, and the university of new mexico, with funds allotted by the works progress administration (lambert, 1954). paa-ko is located between albuquerque and santa fe, new mexico (lambert, 1954). occupied from ce 1300-1425, paa-ko was established through population migration during the pueblo iv period (lambert 1954). this study uses a population count of 178 individuals, the majority of which are infants and children (9 years of age and younger). taphonomic processes affecting the recovered dentition include severe postmortem damage and postmortem loss, both of which impacted observation and recording. for this study, only individuals with intact, fully erupted anterior maxillary dentition were used. dental morphology was observed and recorded for 53 maxillary lateral incisors associated with 34 individuals; nine subadults (10-17 years), and 25 adults (18 + years). males and females were not considered separately because of low correlation between sex bias and trait expression (scott and turner 1997; kuba 2006). dental morphology of 37 discrete and continuous dental traits were examined and scored following the extensive sequencing of turner et al’s (1991) asudas to ensure accurate recognition. for this study variations of shovel, double shovel, interruption grove, and tuberculum dentale were the focus. in cases where dental attrition or taphonomic processes inhibited scoring of morphological traits, traits were recorded as missing data. results fifty-three maxillary incisors from 34 individuals were examined. table 1 shows trait frequencies. the most frequently expressed trait was shoveling, occurring in 26 individuals (79%, n=43 teeth). of these individuals, 13 (38.2%, n=13 teeth) exhibit either shovel, or marked shovel (turner et al. 1991). barrel-shaped incisor was exhibited in one individual (2.9%, n=2 teeth). double shoveling was exhibited in 12 individuals (35%, n=17 teeth). interruption groove was expressed in 21 individuals (61%, n=32 teeth). tuberculum dentale was present in 22 individuals (64.7%, n=35 teeth). thirteen of the individuals (55.8%, n=19 teeth) with a tuberculum dentale expressed either a weak cuspule with a free apex or a strong cusp with free apex, which are the highest asudas grades (turner et al 1991:16). one individual (2.9%, n=1 tooth) expressed a triform, bifurcated lateral incisor. this tooth exhibited a developed transverse ridge on the incisal surface originating from the tuberculum dentale dividing two fossae (lee et al. 1988; bailey-schmidt 1995). mesiodistal and labiolingual dimensions of this tooth were greatly expanded as a result of this morphological arrangement. four individuals (11.7%, n=4 teeth) expressed a peg-shaped, or conical, lateral incisor. eight individuals (23.5%, n=11 teeth) expressed some degree of all observed traits (shovel, double shovel, interruption groove, tuberculum dentale). six individuals (17.6%, n=7 teeth) exhibit maxillary lateral incisor variants which are considered rare in expression (barrel-shovel, peg-incisor, triform; scott and turner, 1997). table 1. frequency of lateral incisor trait traits # of individuals scored and percent expressed n % shovel 26 0.790 full shovel 8 0.235 marked 5 0.147 barrel 1 0.290 double shovel 12 0.350 interruption groove 21 0.610 tuberculum dentale 22 0.647 well-developed 13 0.382 triform 1 0.029 peg-shaped 4 0.117 17 discussion paa-ko is a quintessential example of prehistoric southwest dental morphological variation. there is a high prevalence of all four maxillary lateral incisor traits analyzed (shovel, double shovel, tuberculum dentale, and interruption groove) and most correspond with previously reported native american samples (sofaer et al., 1972; scott et al., 1983; bailey-schmidt, 1995; scott and turner, 1997; mcclelland, 2003). seventeen percent of the paa-ko sample exhibits uncommon lateral incisor trait variants, barrel-shovel (figure 1), triform (figure 2), and peg-shape (figure 3), a higher frequency than other reported prehistoric southwest populations (sofaer et al., 1972; burnett and weets, 2001; mcclelland, 2003). an outline of specific migration patterns is beyond the scope of this paper because its focus remains on one population; however, a discussion is necessary to determine the high variability and rare trait expression within the maxillary lateral incisor of paa-ko. increased trait prevalence is most likely the result of gene flow into the southwest followed by period of population isolation (malhi et al., 2003; leblanc et al., 2008). migration into the region, including into the san juan basin (benson et al., 2007) where paa-ko is located, occurred prior to the pueblo iv period. lambert (1953) argues that paa-ko was established by communities from the west. high frequencies of morphological variation and prevalence of uncommon traits may be reflective of the broad admixture resulting from eastern migration (malhi et al., 2003).the pueblo pattern of large site abandonment followed by isolated community aggregation (fagan, 2000) likely resulted in short term genetic drift, and contributed to the higher prevalence of rare dental traits observed within paa-ko. adaptive significance can also influence the expression of certain dental traits, as functional demands impact tooth morphology (hunter and jernval, 1995). shoveling and tuberculum dentale may be adapted to strengthen teeth by adding to structural durability with extra enamel (dahlberg, 1963; bailey-schmidt, 1995).however, this explanation is less likely to be the case because traits fig. 1. barrel-shovel lateral incisors observed in burial 1971-82-122. fig. 2.triform variant of right lateral incisor observed in burial 1971-82-21. fig. 3. peg-incisor observed on left maxillary lateral incisor of burial 1971-82-96. 18 associated with advantageous adaptive changes would be seen in high prevalence throughout the region, not localized to paa-ko. additionally, anterior teeth are not used in primary mastication. conclusion prehistoric native american southwest exhibits high dental variability in the lateral incisors (sofaer et al., 1972; bailey-schmidt, 1995; scott and turner, 1997; mcclelland, 2003), especially at paako, new mexico (ce 1300-1425). high prevalence of four discreet traits (shovel, double shovel, interruption groove, and tuberculum dentale) and their morphological variants (barrel-shovel, pegincisors, triform) were observed in paa-ko, new mexico. the high observed variability is likely the result of gene flow into the region followed by short term population isolation prior to the pueblo iv period (ce 900-1500). even though maxillary lateral incisor traits are good indicators of genetic relationships and population movement (scott and turner, 1997),they are underrepresented in the literature. this article provides an additional prehistoric southwest population for future research on regional behaviors, migration, and population affinity. acknowledgements thanks go to the san diego museum of man for the opportunity to conduct research on this collection. to tori d. randall, thank you for your support of this project. thank you to g. richard scott, and shara bailey for aiding in the identification of the triform lateral incisor. special thanks go to debbie guatelli-steinberg for guidance and advice in analysis and writing. the author thanks the editor-in-chief christopher w. schmidt and anonymous reviewers for their critical advice on this work. literature cited bailey-schmidt s. 1995. population distribution of the tuberculum dentale complex and anoma lies of the maxillary anterior teeth.masters the sis, department of anthropology, arizona state university. benson lv, berry ms, jolie ea, spangler jd, stahle dw, hattori e.m., 2007. possible impacts of early-11th-, middle-12th, and late-13th century droughts on western native americans and the mississippian cahokians. quaternary science reviews 26: 336-350. bollini ga, rodriguez-florez cd, colantonio, se. 2008. dental non-metric traits in a pre conquest sample from tastil region in argentina south america. bulletin of the international association of paleodontology 2(1): 1925. burnett se, weets jd. 2001. maxillary canine first premolar transposition in two native american skeletal samples from new mexico. am j phys anthropol 16: 45-50. dahlberg aa 1963. dental evolution and cul ture. human biology 35: 237-249. dean js. 1996. demography, environment, and subsistence stress, in: tainter ja, tainter bb (eds), evolving complexity and environ mental risk in the prehistoric southwest. fagan bm. 2000. ancient north america: the archaeology of a continent. new york: thames and hudson. hunter jp, jernvall j. 1995. the hypocone as a key innovation in mammalian evolution. pro ceedings of the national academy of sciences, usa 92: 10718-10722. irish jd, guatelli-steinberg d. 2003. ancient teeth and modern human origins: an ex panded com parison of african plio pleistocene and recent world dental samples. j hum evol 45: 113-144. kieser ja, preston cb. 1981. dentition of the lengua indians of paraguay. american j phys anthropol 55: 485-490. kuba cl. 2006. nonmetric traits and the detec tion of familial groups in archaeological re mains. dissertation, department of anthropol ogy, arizona state university. lambert mf, 1954.paa-ko, archaeological chroni cle of an indian village in north central new mexico. the school of american research, monograph 19, parts i-v, santa fe, nm. leblanc sa. 1999. prehistoric warfare in the american southwest. university of utah press, salt lake city, utah. leblanc sa, turner ii cg, morgan me. 2008. genetic relationships based on discrete dental traits: basketmaker ii and mimbres. intl j osteo archaeol 18: 109-130. le bot p, salmon d. 1977. congenital defects of the upper lateral incisors (uli): condition and measurements of the other teeth, measurements of the superior arch, head and face. am j 19 phys anthropol 46: 231-244. malhi rs, mortensen hm, eshleman ja, kemp bm, lorenz jg, kaestle fa, johnson jr, gorodezky c, smith dg. 2003. native american mtdna prehistory in the american southwest. am j phys anthropol 120: 108-124. mcclelland ja. 2003. refining the resolution of biological distance studies based on the analysis of dental morphology: detecting subpopulations at grasshopper pueblo. dissertation, depart ment of anthropology, university of arizona. scott gr, yap potter rh, noss jf, dahlberg aa, dahlberg t. 1983. the dental morphology of pima indians. am j phys anthropol 61: 13 31. scott gr, turner ii cg, 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cam bridge university press, cambridge, uk.. sofaer ja, niswander jd, maclean cj, work man pl. 1972. population studies on southwest indian tribes. v. tooth morphology as an indi cator of biological distance. am j phys anthro pol 37: 357-366. turner cg ii, nichol, cr, scott gr. 1991. scor ing procedures for key morphological traits of the permanent dentition: the arizona state uni versity dental anthropology system, in: kelly, m.a., larsen, c.s. (eds.), advances in dental anthropology. wiley-liss, inc., new york, pp. 13-31. turner cg ii, swindler ds. 1978. the dentition of new britain west nakanai melanesians.viii peopling of the pacific. am j phys anthropol 49: 361-372. wilcox dr, haas j. 1994. the scream of the but terfly: competition and conflict in the prehis toric southwest, in: gumerman gj (ed.), themes in southwest prehistory. school of american research press, santa fe, nm, pp. 8 108. 3 dental anthropology 2021 │ volume 34│ issue 01 growth rates of accessory human enamel: a histological case study of a modern-day incisor from northern england christopher aris 1* and emma street 2 1 university of kent, canterbury, uk 2 no affiliations the study of modern human enamel growth rates via histological analysis is common within the study of biological anthropology and bioarchaeology, commonly focusing on the variation between cusps of the same tooth (e.g. mahoney, 2008), within single populations (e.g. schwartz et al., 2001), and between populations (e.g. smith et al., 2007; aris et al., 2020a, 2020b). a common trend between these lines of research is the exclusive use of what are deemed as dental samples containing no evidence of pathology, stress markers, or growth of accessory enamel (defined here as: growth of enamel outside of the features typically used to define and identify human tooth types). while past research has touched on how some human enamel growth features vary between individuals suffering from stress and those not suffering from stress resulting in dental morphologies, these typically concern the accuracy of making certain calculations relating to enamel growth (lukacs & guatelli -steinberg, 1994; guatelli-steinberg & lukacs, 1999), and the development of non-accessory enamel (defined here as: growth of the enamel features which define how human tooth types are identified and classified) in individuals presenting evidence of stress on their dental morphology (e.g. fitzgerald & saunders, 2005). comparison of enamel growth rates collected from teeth presenting accessory enamel to those with no evidence of stress markers or non-metric traits from the same population, and comparison of accessory enamel growth to the growth of non-accessory enamel within the same tooth, have yet to be conducted. this project aims to begin to address these issues and widen our understanding of accessory enamel growth in modern-day humans through the case study of a modern-day upper first incisor. background amelogenesis and daily enamel growth amelogenesis is the process of secretion and mineralization of protein matrix by ameloblast cells (boyde, 1989; nanci & smith, 1992; smith & nanci, 1995). during the secretory stage of amelogenesis, abstract this study investigates enamel growth of a modern-day human upper first incisor (s197) possessing a talon cusp (accessory cusp). growth rates collected from the accessory enamel are compared to data collected from the primary cusp and cusps of a standard incisor sample from the same population. upper first incisors (n=12) and s197 were analysed using histological methods. daily secretion rates (dsrs) were calculated for inner, mid, and outer regions of cuspal and lateral sites. additional dsrs were calculated for equivalent regions of s197’s accessory cusp. s197’s primary cusp dsrs were significantly faster than the accessory cusp for all lateral regions, but significantly slower in the inner and mid cuspal regions. s197’s primary cusp dsrs were also significantly slower than the standard incisor sample for all regions except the lateral cuspal. the dsrs of the standard sample were significantly faster than those of s197’s accessory cusp for all lateral regions, but significantly slower in the inner cuspal region. this case study displays that human teeth possessing accessory cusps can present varying dsrs to teeth lacking accessory enamel from the same population, and that accessory enamel growth may not follow the same pattern of increasing dsrs along the length of enamel prisms. *correspondence to: christopher aris department of archaeology ella armitage building university of sheffield sheffield, uk c.aris@sheffield.ac.uk keywords: incisor, enamel, daily secretion rates 4 dental anthropology 2021 │ volume 34│ issue 01 ameloblast secretion is altered according to a daily circadian rhythm, producing short-period markers along the length of enamel prisms (e.g., asper, 1916; gysi, 1931; massler & schour, 1946; okada, 1943; kajiyama, 1965; dean et al., 1993; smith & nanci, 2003). these daily forming markers are known as cross striations (e.g. boyde, 1963; 1990; kajiyama, 1965; bromage, 1991; dean, 1995; fitzgerald, 1995, 1998; antoine, 2000; antoine et al., 2009). the formation of cross striations causes alterations in the refractive index of enamel prisms, making them observable in thin sections under transmitted light (e.g. berkovitz et al., 2002; zheng et al., 2013). daily secretion rates (dsrs) can be calculated from cross striations. these rates accelerate from inner enamel regions proximal to the enamel dentine junction towards the outer enamel surface (e.g. beynon et al., 1991 beynon et al., 1998; reid et al., 1998; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a, 2020b). daily secretion rates are also faster relative to their proximity to the dentine horn (beynon et al., 1991). due to dsrs varying within a tooth, analysis of these rates are undertaken for specific regions (e.g. dean, 1998) where the crown is divided into cuspal, lateral, and cervical enamel, and then further subdivided into inner, mid, and outer regions. typically, dsrs are broadly similar when equivalent regions are compared between cusps within a molar (mahoney, 2008). analysis of dsrs for human samples have examined variations within individual teeth (mahoney, 2008), differences between biologically male and female groups (schwartz et al., 2001), and more recently variations between populations (aris et al., 2020a, 2020b). despite the breadth of these studies, they have universally used teeth absent of evidence of stress, pathology, and accessory enamel growth. thus, our understanding of how human dsrs vary in accessory enamel in comparison to non-accessory enamel is limited. enamel growth patterns within pathological cases while the dsrs of accessory enamel have not yet been analysed, certain features of enamel growth have been analysed for individuals presenting signs of stress on their dentition. these studies have focused on the possible changes in amelogenesis, which leads to the formation of enamel growth defects observable from internal and external analysis. lukacs and colleagues have published a series of papers explaining the pattern and expression of enamel defects in modern humans. these can vary due to diet, geographic location, and climate. in particular, these papers present evidence of longer crown formation times (cfts) in stressed individuals (lukacs et al., 1989; lukacs, 1991, 1992, 1999; lukacs & joshi, 1992; lukacs & pal, 1993; lukacs & guatelli-steinberg, 1994; luckas & walimbe, 1998; guatelli-steinberg & lukacs, 1999). as cfts are directly related to the products of daily enamel growth (e.g. massler & schour, 1946) there is potential that accessory enamel possesses growth rates which vary from non-accessory enamel. fitzgerald and saunders (2005) investigated the possibility of using enamel defects to predict the age at which stress was incurred and thus improve the way in which we interpret the influence of stress on enamel growth patterns. this concept was based on the ability to age through examining interior enamel structures, and that these structures would be notably altered during stressful events. through the use of a large sample size (274 teeth from 127 roman subadults), they concluded that enamel formation patterns are more highly impacted according to the severity of the cause of stress, and that there is no minimum requirement of stress level for enamel to be effected (fitzgerald & saunders, 2005). multiple papers have since been published on this topic, all conclusively stating that stress impacts enamel structures, significantly increases cfts, and reduces the reliability of dsr calculations (reid & dean, 2006; holt et al., 2012; birch & dean, 2014; primeau et al., 2015). as a result of these studies, we can reliably say that nonaccessory enamel grows differentially in individuals presenting evidence of stress. it is therefore important to expand our understanding of how accessory enamel grows in relation to non-accessory enamel. material and methods dental sample upper permanent first incisors (n=13) were selected from a modern-day collection consisting of teeth extracted between 1964 and 1973 at dental surgeries in northern england and southern scotland. all 13 samples originated from newcastleupon-tyne, including an incisor presenting an accessory enamel cusp (s197). the accessory cusp of s197 has developed on the cingulum and reached beyond half the distance to the incisal edge (figure 1), as such it is diagnosed as a talon cusp (edgar et al., 2016). the remaining 12 incisors made up a standard sample, with each tooth presenting no evidence of stress, pathology, or accessory enamel growth. right teeth were selected unless it was 5 dental anthropology 2021 │ volume 34│ issue 01 unavailable or the left was better preserved. the collection itself is curated at the skeletal biology research centre, university of kent, as part of the ucl/kent collection. ethical approval for the histological analysis of this dental sample was obtained from the uk national health service research ethics committee (rec reference: 16/ sc/0166; project id: 203541). sample preparation resin casts were produced for each incisor prior to any destructive analysis, and were produced using standard methods (aris, 2020). the casts reproduced the surface morphology of the tooth crown allowing for future study of microwear, crown morphology, and enamel surface features including linear enamel hypoplasia and perikymata. thin sections were produced using standard histological procedures (e.g. schwartz et al., 2005; mahoney, 2008; aris, 2020). the incisors were embedded in an epoxy resin and hardener mixture (buehler®) to minimise the chance of the teeth fracturing during sectioning. embedded samples were then cut at a low speed using a diamond-edged wafering blade (buehler® isomet 1000 precision cutter) at a longitudinal angle through the apex of the incisal crowns. the samples were then mounted on glass microscope slides and lapped using progressively finer grinding pads (buehler®) until around 120µm in thickness. ground samples were polished using 0.3µm aluminium oxide powder until evidence of lapping was removed from the mounted dental samples. polished samples were then placed within an ultrasonic bath for two minutes in order to remove any remaining debris before being dehydrated using 90% and 100% ethanol-based solutions (fisher scientific®). the dehydrated sections were finally cleared using histoclear® and mounted with a glass cover slip using a mounting medium (dpx®). all sections were examined using polarised light microscopy (olympus bx53 upright microscope). analysis and image capture was conducted using micro imaging software (cellsens) (see below for detail). daily secretion rates the dsrs for the incisors were calculated for the inner, mid, and outer areas of the lateral and cuspal enamel sites of each tooth using standard methods (e.g. beynon et al., 1991a; schwartz et al., 2001; mahoney, 2008; aris et al., 2020a, 2020b). each region within the cuspal and lateral sites was determined by dividing the length of the enamel regions into three equidistant portions, following the longitudinal axis of local enamel prisms (figure 2). the lateral enamel areas were determined within the section of imbricational enamel equidistant between the dental cervix and dentine horn. regions of cuspal enamel were determined within the appositional enamel starting near the dentine horn. additional dsrs were calculated for isolated regions of s197’s accessory cusp (see figure 2). these regions were selected in a fashion as to mirror the cuspal and lateral regions of the primary cusp. within each enamel region a measurement was made of five consecutive cross striations along the length of an enamel prism. this measurement was subsequently divided by five, giving a mean daily rate of matrix secretion (µm/day). this process was repeated to produce six mean dsrs for each region. for the standard incisor sample these results were then similarly divided to give a grand mean and standard deviation, following the standard statistical and methodological approaches of studying human enamel growth rates (e.g. beynon et al., 1991 beynon et al., 1998; reid et al., 1998; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a, 2020b). for s197 the six mean dsrs for each region were kept separate for future analysis. all cross striation measurements were taken between 20x and 40x magnification (figure 3). statistical analysis independent sample t-tests were used to compare mean equivalent regional dsrs between the selected samples. first, the same dsrs of the primary cusp and accessory cusp of s197 were compared. figure 1. depictions of upper first permanent incisor s197 prior to sectioning highlighting the regions defined as accessory and non-accessory enamel. moving left to right the images display the tooth from the labial, lingual, and mesial directions. 6 dental anthropology 2021 │ volume 34│ issue 01 figure 2. cross section of sample 197 displaying the regions from which dsrs were collected. right superimpositions show the cuspal (top) and lateral (bottom) sites of the primary cusp. left superimpositions show the cuspal (top) and lateral (bottom) sites of the accessory enamel. white squares represent the inner, mid, and outer regions of each site respectively moving from the enamel dentine junction towards the outer enamel surface. daily secretion rates were collected from healthy clinical teeth from equivalent cuspal and lateral sites to the right superimpositions. figure 3. cross section of the cuspal enamel site of the primary cusp of sample 197. the right superimposition displays a portion of the mid cuspal region, and the white arrows indicate individual cross striations. 7 dental anthropology 2021 │ volume 34│ issue 01 second, the dsrs collected from the primary cusp enamel of s197 were compared to those of the standard clinical sample. third, the dsrs of the accessory enamel of s197 were compared to those of the standard clinical sample. all statistical analyses were conducted using spss 24.0. results accessory enamel dsrs compared to primary cusp dsrs table 1 displays the results of comparing the mean dsrs of the primary cusp enamel to those of the accessory cusp enamel, all collected from s197. for the inner and mid regions of the lateral enamel the primary cusp enamel presented significantly faster dsrs. these were faster by a mean rate of 0.53µm/ day (p<0.00) in the inner region, and 0.47µm/day (p=0.01) in the mid region. conversely, accessory enamel presented significantly faster dsrs for the inner and mid cuspal enamel regions. these were faster by a mean rate of 2.14µm/day (p<0.00) in the inner region, and 1.02µm/day (p<0.00) in the mid region. non-accessory enamel dsrs compared to rest of population table 2 displays the results of comparing the mean dsrs of the primary cusp enamel of s197 to those of the standard clinical sample. for all regions of the lateral enamel, the standard sample presented significantly faster dsrs. these were faster by a mean rate of 0.27µm/day (p=0.01) in the inner region, 0.51µm/day (p<0.00) in the mid region, and 0.37µm/day (p=0.02) in the outer region. the standard sample also presented significantly faster dsrs for the inner and mid cuspal enamel regions. these were faster by a mean rate of 0.69µm/day (p<0.00) in the inner region, and 0.65µm/day (p<0.00) in the mid region. accessory enamel dsrs compared to rest of population table 3 displays the results of comparing the mean dsrs of the accessory enamel of s197 to those of the standard clinical sample. for all regions of the lateral enamel, the standard sample presented significantly faster dsrs. these were faster by a mean rate of 0.80µm/day (p<0.00) in the inner region, 0.98µm/day (p<0.00) in the mid region, and 0.59µm/day (p<0.00) in the outer region. conversely, the accessory enamel sample presented significantly faster dsrs for the inner cuspal enamel region by a mean rate of 1.45µm/day (p<0.00). discussion inter-regional enamel growth of s197 the lateral enamel dsrs of the primary cusp were significantly faster than those of the accessory enamel in the inner and mid regions. conversely, the accessory enamel cuspal dsrs were significantly faster than those of the primary cusp for the inner and mid regions (see table 1). this finding goes against those of past research, which found table 1. results of the independent samples t-tests comparing the mean regional dsrs (µm/day) of the accessory enamel of sample 197 to the primary cusp enamel of sample 197. significant results are marked in bold, *p<0.00. enamel region sample n mean min max s.d. sig. lateral enamel inner accessory 6 2.24 2.02 2.37 0.14 0.00* primary cusp 6 2.77 2.48 2.98 0.19 mid accessory 6 2.51 2.37 2.81 0.16 0.01 primary cusp 6 2.98 2.67 3.35 0.24 outer accessory 6 3.13 2.89 3.78 0.33 0.42 primary cusp 6 3.35 2.88 3.77 0.34 cuspal enamel inner accessory 6 4.65 4.30 4.98 0.21 0.00* primary cusp 6 2.51 2.14 2.78 0.12 mid accessory 6 3.91 3.37 4.41 0.37 0.00* primary cusp 6 2.89 3.44 2.40 0.25 outer accessory 6 3.71 3.09 4.14 0.46 0.81 primary cusp 6 3.84 3.48 4.24 0.27 8 dental anthropology 2021 │ volume 34│ issue 01 table 2. results of the independent samples t-tests comparing the mean regional dsrs (µm/day) of the healthy samples to those collected from the primary cusp enamel of sample 197. significant results are marked in bold, *p<0.00. enamel region sample n mean min max s.d sig. lateral enamel inner primary cusp 6 2.77 2.48 2.98 0.19 0.01 healthy 12 3.04 2.56 3.32 0.21 mid primary cusp 6 2.98 2.67 3.35 0.24 0.00* healthy 12 3.49 2.86 3.80 0.27 outer primary cusp 6 3.35 2.88 3.77 0.34 0.02 healthy 12 3.72 3.14 4.06 0.25 cuspal enamel inner primary cusp 6 2.51 2.14 2.78 0.12 0.00* healthy 8 3.20 2.84 3.43 0.23 mid primary cusp 6 2.89 3.44 2.40 0.25 0.00* healthy 8 3.54 3.16 3.86 0.22 outer primary cusp 6 3.84 3.48 4.24 0.27 0.69 healthy 8 3.89 3.36 4.09 0.23 table 3. results of the independent samples t-tests comparing the mean regional dsrs (µm/day) of the healthy samples to those collected from the accessory enamel of sample 197. significant results are marked in bold, *p<0.00. enamel region sample n mean min max s.d sig. lateral enamel inner accessory 6 2.24 2.02 2.37 0.14 0.00* healthy 12 3.04 2.56 3.32 0.21 mid accessory 6 2.51 2.37 2.81 0.16 0.00* healthy 12 3.49 2.86 3.80 0.27 outer accessory 6 3.13 2.89 3.78 0.33 0.00* healthy 12 3.72 3.14 4.06 0.25 cuspal enamel inner accessory 6 4.65 4.30 4.98 0.21 0.00* healthy 8 3.20 2.84 3.43 0.23 mid accessory 6 3.91 3.37 4.41 0.37 0.05 healthy 8 3.54 3.16 3.86 0.22 outer accessory 6 3.71 3.09 4.14 0.46 0.74 healthy 8 3.89 3.36 4.09 0.23 9 dental anthropology 2021 │ volume 34│ issue 01 dsrs to remain similar between equivalent regions of different non-accessory cusps in typically multicusped teeth (mahoney, 2008). this unusual variation in dsr differences between the cusps is the product of the cuspal dsrs of the accessory cusp slowing with distance from the enamel dentine junction (edj) along the enamel prism pathway. this trend also differs to that seen in past research, which has shown permanent enamel growth rates of non-accessory enamel to always accelerate with distance from the edj (e.g. beynon et al., 1991, 1998; reid et al., 1998; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a, 2020b). this finding, in particular, demands further investigation, primarily to identify if the reversed growth pattern in cuspal dsrs of accessory enamel growth is consistent in other human samples. should this be the case then the expected principle notion of enamel growth rates increasing with distance, a principle formulated on teeth not presenting accessory enamel growth from the edj, would need to be addressed. it is plausible that this principle, highly supported by the data of past research (e.g. beynon et al., 1991; beynon et al., 1998; reid et al., 1998; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a, 2020b) can only accurately be applied to growth of non-accessory enamel. further research on the growth rates of accessory enamel is therefore required in order to create an equivalent growth principle for non-accessory enamel. primary cusp enamel growth compared to standard sample despite being the primary cusp of s197 and displaying standard morphology for an upper permanent first incisor, the regional enamel dsrs varied significantly from the mean dsrs of the standard sample (table 2). mean dsrs of all lateral enamel regions, and the inner and mid cuspal regions, were significantly slower in s197. however, outer cuspal dsrs were slower by only a mean rate of 0.05µm/day in s197. overall, while this research only presents a preliminary case study, the data suggests that such enamel will grow slower than the standard sample cohort of the same tooth type within the same population. this finding primarily supports the use of teeth possessing no abnormal or excess enamel in past growth rate studies (e.g. beynon et al., 1991; beynon et al., 1998; reid et al., 1998; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a, 2020b), as there is now clear potential for significant differences between teeth that do and do not present accessory enamel growth as defined here. perhaps more importantly, there is new incentive for future research to continue analysing the growth rates throughout all regions and types of enamel from all tooth types. such research will serve to expand our knowledge of the growth rate patterns common in human dentition, by identifying if non-accessory enamel growth rates slow in the presence of accessory enamel on the same tooth, or if s197 is a unique case. future research should also examine the growth rates of less extreme non-accessory enamel growth than that of s197. this would help ascertain whether the extremity of accessory enamel growth is related to the slowing growth rates of the non-accessory enamel. accessory cusp enamel growth compared to standard sample the lateral enamel dsrs of the accessory cusp of s197 presented significantly slower rates compared to those of the standard sample (table 3). conversely, the inner cuspal dsrs of the accessory cusp were significantly faster. the mid cuspal region was also faster by a mean rate of 0.37µm/day, but the outer cuspal region presented minimal variation to the standard sample (table 3). these results demonstrate the erratic and inconsistent growth patterns of the accessory enamel of s197. it is particularly unusual that the cuspal accessory enamel growth slowed from inner to outer regions, and that the outer region mean dsr climaxed at a similar rate to equivalent dsrs of the standard sample. further research is required to ascertain whether this is a unique phenomenon or the standard growth pattern for accessory enamel. however, it should be noted that accessory enamel manifestations differ between different dental non-metric traits whose etiology includes excess enamel formation. future research investigating the growth of accessory enamel should therefore consider analysing growth rates of teeth grouped according to their diagnosed traits and tooth types, as it should not be assumed that accessory enamel grows at similar rates between these groups. this principle should be applied to all future research advised here to avoid inaccurately grouping the growth patterns of all non-accessory enamel types. conclusions the inter-regional differences in the growth rates collected from s197 were erratic, and in some enamel regions in direct contradiction with those expected of human incisors and multi-cusped teeth. firstly, the differences between the equivalent regional dsrs of the primary and secondary 10 dental anthropology 2021 │ volume 34│ issue 01 cusp of s197 vary from the similarities observed in past research comparing non-accessory cusps of the same teeth. secondly, the presence of extreme accessory enamel formation appeared to slow the growth rates of the non-accessory enamel when compared to the growth rates of a standard sample of teeth lacking accessory enamel growth. finally, the dsrs from the accessory cusp of s197 highlight how accessory enamel growth rates will not necessarily follow the trend of increasing rates with distance from the edj. the lack of additional research greatly limits our understanding of these findings. overall, it is clear that more research into the growth rates of accessory enamel, as well as nonaccessory enamel of the same teeth, is needed. ideally such research will analyse different tooth types, and teeth with different diagnosed nonmetric traits, independently. acknowledgments we would like to thank the university of kent for granting permission to sample teeth from their clinical collection. further thanks also go to annie robertson for her assistance and artistic talents. thanks also go to the anonymous reviewer and editor for their invaluable feedback. references antoine, d. (2000). evaluating the periodicity of incremental structures in dental enamel as a means of studying growth in children from past human populations (doctoral dissertation, university college london). antoine, d., hillson, s., & dean, m. c. (2009). the developmental clock of dental enamel: a test for the periodicity of prism cross‐striations in modern humans and an evaluation of the most likely sources of error in histological studies of this kind. journal of anatomy, 214(1), 45-55. aris, c. (2020). the histological paradox: methodology and efficacy of dental sectioning. papers from the institute of archaeology, 29(1), 1-16. aris, c., mahoney, p., & deter, c. (2020a). enamel thickness and growth rates in modern human permanent first molars over a 2000 year period in britain. american journal of physical anthropology, 173, 141-157. aris, c., mahoney, p., o'hara, m. c., & deter, c. (2020b). enamel growth rates of anterior teeth in males and females from modern and ancient british populations. american journal of physical anthropology, 173, 236-249. asper, h. (1916). uber die ‘‘braune retzius’sche parallelsteifung’’ im schmelz der menschlichen zahne. schweiz vjschr. zahnhlk, 26(1), 275-314 berkovitz, b. k. b., holland, g. r., & moxham, b. j. (2002). oral anatomy, embryology and histology. mosby incorporated. beynon, a. d., clayton, c. b., ramirez rozzi, f. v. r., & reid, d. j. (1998). radiographic and histological methodologies in estimating the chronology of crown development in modern humans and great apes: a review, with some applications for studies on juvenile hominids. journal of human evolution, 35(4), 351-370. beynon, a. d., dean, m. c., & reid, d. j. (1991). histological study on the chronology of the developing dentition in gorilla and orangutan. american journal of physical anthropology, 86(2), 189-203. birch, w., & dean, m. c. (2014). a method of calculating human deciduous crown formation times and of estimating the chronological ages of stressful events occurring during deciduous enamel formation. journal of forensic and legal medicine, 22, 127-144. boyde, a. (1989). enamel. in teeth (pp. 309-473). springer, berlin, heidelberg. boyde, a., (1990). developmental interpretations of dental microstructure. in derousseau, j.c. (ed.), primate life history and evolution (pp. 229 -267). new york: wiley-liss. boyde, a. (1990). developmental interpretations of dental microstructure. in derousseau, j.c. (ed.), primate life history and evolution (pp. 229 -267). new york: wiley-liss. bromage, t. g. (1991). enamel incremental periodicity in the pig‐tailed macaque: a polychrome fluorescent labeling study of dental hard tissues. american journal of physical anthropology, 86(2), 205-214. dean, m. c. (1995). the nature and periodicity of incremental lines in primate dentine and their relationship to periradicular bands in oh 16 (homo habilis). in j. m. cecchi (ed.), aspects of dental biology: paleontology, anthropology and evolution (pp. 239–265). florence: international institute for the study of man. dean, m. c. (1998). a comparative study of cross striation spacings in cuspal enamel and of four methods of estimating the time taken to grow molar cuspal enamel in pan, pongo and homo. journal of human evolution, 35(4), 449-462. dean, m. c., beynon, a. d., reid, d. j., & whittaker, d. k. (1993a). a longitudinal study of tooth growth in a single individual based on long‐and short‐period incremental markings in dentine and enamel. international journal of osteoarchaeology, 3(4), 249-264. edgar, h. j. h., willermet, c., ragsdale, c. s., 11 dental anthropology 2021 │ volume 34│ issue 01 o'donnell, a., & daneshvari, s. (2016). frequencies of rare incisor variations reflect factors influencing precontact population relationships in mexico and the american southwest. international journal of osteoarchaeology, 26 (6), 987-1000. fitzgerald, c. m. (1995). tooth crown formation and the variation of enamel microstructural growth markers in modern humans (doctoral dissertation, university of cambridge). fitzgerald, c. m. (1998). do enamel microstructures have regular time dependency? conclusions from the literature and a large-scale study. journal of human evolution, 35(4-5), 371386. fitzgerald, c. m., & saunders, s. r. (2005). test of histological methods of determining chronology of accentuated striae in deciduous teeth. american journal of physical anthropology, 127(3), 277-290. guatelli‐steinberg, d., & lukacs, j. r. (1999). interpreting sex differences in enamel hypoplasia in human and non‐human primates: developmental, environmental, and cultural considerations. american journal of physical anthropology, 110(s29), 73-126. gysi, a. (1931). metabolism in adult enamel. dental dig, 37, 661-668 holt, s. a., reid, d. j., & guatelli-steinberg, d. (2012). brief communication: premolar enamel formation: completion of figures for aging leh defects in permanent dentition. dental anthropology journal, 25(1), 4-7. kajiyama, s. (1965). total number of regular incremental lines (regulare parallelstreifen nach asper) in the enamel of human permanent teeth. journal of nihon university school of dentistry, 39, 77-83. lukacs, j. r. (1991). localized enamel hypoplasia of human deciduous canine teeth: prevalence and pattern of expression in rural pakistan. human biology, 63(4), 513-522. lukacs, j. r. (1992). dental paleopathology and agricultural intensification in south asia: new evidence from bronze age harappa. american journal of physical anthropology, 87(2), 133-150. lukacs, j. r. (1999). enamel hypoplasia in deciduous teeth of great apes: do differences in defect prevalence imply differential levels of physiological stress?. american journal of physical anthropology, 110(3), 351-363. lacruz, r. s., & bromage, t. g. (2006). appositional enamel growth in molars of south african fossil hominids. journal of anatomy, 209(1), 1320. lukacs, j. r., & guatelli-steinberg, d. (1994). daughter neglect in india: leh prevalence and the question of female biological superiority. american journal of physical anthropology, supplement, 18, 132. lukacs, j. r., & joshi, m. r. (1992). enamel hypoplasia prevalence in three ethnic groups of northwest india: a test of daughter neglect and a framework for the past. recent contributions to the study of enamel developmental defects. journal of paleopathology monograms publications, 2, 359-372. lukacs, j. r., & pal, j. n. (1993). mesolithic subsistence in north india: inferences from dental attributes. current anthropology, 34(5), 745-765. lukacs, j. r., & walimbe, s. r. (1998). physiological stress in prehistoric india: new data on localized hypoplasia of primary canines linked to climate and subsistence change. journal of archaeological science, 25(6), 571-585. mahoney, p. (2008). intraspecific variation in m1 enamel development in modern humans: implications for human evolution. journal of human evolution, 55(1), 131-147. massler, m., & schour, i. (1946). growth of the child and the calcification pattern of the teeth. american journal of orthodontics and oral surgery, 32(9), 495-517. nanci, a. and smith. c. e. (1992). development and calcification of enamel. in e. bonucci, (ed.) calcification in biological systems (pp 313-343). boca raton, fl: crc press. okada, m. (1943). hard tissues of animal body. highly interesting details of nippon studies in periodic patterns of hard tissues are described. shanghai evening post. medical edition of september 1943, 15-31. primeau, c., arge, s. o., boyer, c., & lynnerup, n. (2015). a test of inter-and intra-observer error for an atlas method of combined histological data for the evaluation of enamel hypoplasia. journal of archaeological science: reports, 2, 384-388. reid, d. j., beynon, a. d., & ramirez rozzi, f. v. r. (1998). histological reconstruction of dental development in four individuals from a medieval site in picardie, france. journal of human evolution, 35(4-5), 463-477. reid, d. j., & dean, m. c. (2006). variation in modern human enamel formation times. journal of human evolution, 50(3), 329-346. 12 dental anthropology 2021 │ volume 34│ issue 01 schwartz, g. t., mahoney, p., godfrey, l. r., cuozzo, f. p., jungers, w. l., & randria, g. f. (2005). dental development in megaladapis edwardsi (primates, lemuriformes): implications for understanding life history variation in subfossil lemurs. journal of human evolution, 49 (6), 702-721. schwartz, g. t., reid, d. j., & dean, c. (2001). developmental aspects of sexual dimorphism in hominoid canines. international journal of primatology, 22(5), 837-860. smith, c. e., & nanci, a. (2003). overview of morphological changes in enamel organ cells associated with major events in amelogenesis. international journal of developmental biology, 39(1), 153-161. smith, t. m., reid, d. j., dean, m. c., olejniczak, a. j., & martin, l. b. (2007). new perspectives on chimpanzee and human molar crown development. in: dental perspectives on human evolution: state of the art research in dental paleoanthropology. springer, dordrecht. pp. 177-192. zheng, j., li, y., shi, m. y., zhang, y. f., qian, l. m., & zhou, z. r. (2013). microtribological behaviour of human tooth enamel and artificial hydroxyapatite. tribology international, 63, 177185. 16 dental anthropology 2022 │ volume 35│ issue 01 assessing error in human dental measurements: a comparison of resin casts, plaster casts, and dental enamel amelia r. hubbard 1, 2* , natasha wilson 2 , giuseppe vercellotti 3 1 anthrotech, inc.; yellow springs, ohio 2 department of sociology and anthropology, wright state university 3 department of anthropology, the ohio state university often circumstances do not allow for the long-term use of skeletal material for research purposes (e.g., repatriation and reburial, length of research visit, etc.). in such cases, ongoing availability of materials, through the production of dental impressions (negative replica of the teeth) and dental casts (lifelike reproductions from impressions) is more practical. however, in order to collect accurate measurement data, differences in error rates between casted dentition and the original teeth must be statistically insignificant so that the results of the study are not impacted. as such it is imperative that a researcher knows whether dental replicas consistently over or underestimate dental dimensions compared to dental enamel, and whether there are significant differences in measurements between casting mediums. similarly, it is crucial to know whether the tools used to measure replicas impact precision. the dimensional stability of the materials used to make dental impressions and dental casts has been widely studied. dental alginates (irreversible hydrocolloid compounds) have long been favored as an impression material in clinical settings for their low cost. this material is not often used by dental anthropologists because it does not have long-term dimensional stability requiring casts to be made within a few hours or a single day (e.g., sedda, casarotto, raustia, and borracchini, 2008). in skeletally based dentitions there is also a higher chance that teeth will be pulled from the jaw given the density of the material and need for a dental tray to hold the alginate. within dental anthropology, the use of polyvinyl siloxane replica materials (pvs) has become more common because it is gentler on skeletal dentitions and multiple casts can be made from the same impression as needed, due to long-term dimensional stability (e.g., chee and abstract technical advances in 3d morphometrics and other forms of digital analysis allow for detailed measurements of dental metrics yet, consistently, dental anthropologists show a publishing preference for measurements using dental calipers. for many researchers, dental casts are often measured when field seasons or collections-based trips do not allow ample time to measure the original teeth. as such, this study aimed to assess differences among measurements of plaster casts, resin casts, and dental enamel to determine if variables such as material softness or shrinkage could lead to measurement error. results of a paired t-test demonstrate no statistically significant difference in buccolingual crown measurements from 23 commingled canines and first molars. likewise, while plaster casts exhibited overall smaller mean (and individual) measurements than enamel and resin, the differences (around 0.04 mm on average) are negligible. we, therefore, conclude that casts can be used in place of original teeth, where needed, and which material type is “best” can be determined by the researcher’s preferred medium. *correspondence to: amelia hubbard anthrotech, inc. e-mail: amy@anthrotech.net keywords: methods, dental anthropology, dental casts, measurement error 17 dental anthropology 2022 │ volume 35│ issue 01 donovan, 1992) as long as temperatures do not fluctuate wildly (kelso, hulsey, and driscoll, 2020). casting material such as gypsum plaster (plaster) are popular when dental morphometrics are the focus, though epoxy resins (resin) have gained popularity among dental anthropologists due to the higher resolution of surface features such as linear enamel hypoplasia and macrowear/ microwear features. a recent study of commonly used resin and plaster materials found that there was no difference in measured size between epoxy resins and dental stone, though the study measured differences using a scanning electron microscope (junior, kreve, and carvalho, 2018). while dental anthropologists can measure casts using a variety of tools ranging from calipers to 3d scans (e.g., al-mulla and murad, 2010; bowes, dear, close, and freer, 2017; keating, knox, bibb, and zhurov, 2008; kumar, phillip, kumar, rawar, priya, kumaran, 2015; reuschl, wieland, stiesch, wenzel, and dittmer, 2016), calipers are still widely used across different field and lab settings. in measurements using calipers material surface hardness is a primary concern as the metal tips must be tightly fit to the surface of the replica and have the potential to leave impressions or scratches on soft surfaces. the most commonly used caliper for measuring dental dimensions is the hillsonfitzgerald caliper (hillson, fitzgerald, and finn, 2005). these calipers are made of a durable metal with thin needle point tips for better fit in interproximal spaces of in-situ dentitions (i.e., teeth implanted in the jaw). of the three dental surfaces, enamel is the hardest and should be unaffected by the adjustment of the metal calipers. resin is also a durable material that is unlikely to yield surface stability, but still softer than dental enamel. in contrast, plaster is soft and can be more easily depressed if the calipers are fit too tightly, though visible inspection of a plaster cast can clarify if the surface is damaged (i.e., a small depression would be readily visible). when previous studies are analyzed to ascertain answers to the questions posed in our study, differences in approach, temporal changes in the quality of impression and casting products, and emergent technologies for measuring dentitions make comparisons problematic. for example, early studies such as hunter and priest (1960) measured dental stone casts taken from alginate impressions and enamel (intra-orally in living patients) using a helios-style caliper (i.e., no needle tips). later studies such as pant, juszczyk, clark, and radford (2008) use pvs impressions materials to make plaster casts to compare with both 3d printed resins (measured by a scanning electron microscope) and digital scans (measured using computer software). further, the conditions in which impressions are taken can have quite an impact. for example, hollinger, lorton, krantz, and connelly (1984) found “material distortion and shrinkage is unpredictable” (308) in impressions of edentulous individuals and highly impacted by the preparation of the dental tray while pant et al. (2008) found that temperature differences impacted the “architectural stability” of pvs. studies such as kelso et al. (2020) demonstrate additional concerns about the impacts of temperatures on long-term storage of materials. this study examines the two most common casting materials (epoxy resin and dental stone) measured using the most common field and lab instrument (hillson-fitzgerald calipers) to assess differences in buccolingual dimensions. assuming careful measurements of each replica’s surface (e.g., checking that the calipers did not leave a visible surface indentation) and demonstrated low surface shrinkage rates of the materials measured, we predicted that buccolingual dimensions of both the plaster and resin casts would not be significantly different than the original dental enamel. however, given the softness of plaster casts we predicted that measurements would consistently register as smaller than either resin or plaster. materials and methods the specimens used in this study were collected from an ossuary located in chiavari, italy in the region of liguria. the ossuary contains the remains of several hundred individuals who were removed from mausoleums and placed in a secondary burial pit as sanctioned by italian law (dpr n.285/1990). with the exception of a limited number of individuals with identifying materials, the remains deposited in the ossuary are commingled and no contextual information is readily available. based on cemetery records, the majority of the remains belong to individuals who lived in chiavari and its hinterland between the late nineteenth and early twentieth century. twenty-three canine and first molar crowns were measured following hillson et al. (2005). dental impressions were made using a highresolution polyvinyl siloxane compound (affinis), preferred by dental anthropologists because of its dimensional stability. these dentition were selected based on larger samples of preserved teeth and, thus, represent a convenience sample. casts were made of gypsum plaster (dentstone) and an epoxy 18 dental anthropology 2022 │ volume 35│ issue 01 resin (epofix) (figure 1). the company modern materials produces dentstone and reports a 0.11 percent “expansion” rate of materials. the company struers produces epofix and claims a 0.3 percent shrinkage rate. dental dimensions were recorded by a single researcher to eliminate interobserver error using paleo-tech’s digital hillsonfitzergerald calipers (hillson et al., 2005), which automatically import measurements into a designated excel spreadsheet when a button is depressed on the caliper’s surface. to reduce intraobserver error, dimensions of each tooth were recorded five times consecutively and reported as an average. only buccolingual crown dimensions were measured in this study because this dental measurement is unaffected by mixed samples of isolated teeth (i.e., not in situ) and those still imbedded in the jaw with neighboring teeth (i.e., in situ). conversely, mesiodistal measurements are more challenging to measure because of tight interproximal spacing between teeth in-situ. therefore, when trying to measure between interproximal spaces, there is a higher likelihood that resin or epoxy would be impressed by the tips of the calipers (and affect measurement). as the sample comprised both loose teeth and those imbedded in the jaw, this posed an increased chance that significant differences in measurements would reflect differences in applied pressure to the cast surface. therefore, because this study used a mixed sample, measurements of mesiodistal differences on the tooth surfaces would not have been comparable. further while comparative analyses between mesiodistal measurements for isolated teeth and in-situ dentitions was possible, overall small samples sizes available in the study did not allow for such a fine scale analysis of the cause of potential measurement variation. to test the first proposal, that buccolingual crown dimensions would not vary significantly between enamel, resin, and plaster, a paired t-test was used (following kieser, 1990). a paired t-test examines mean differences between groups of data and is reported as a t-value and associated significance or p-value (in this case with a 95% confidence interval). to test the second proposal, that buccolingual measurements of plaster would be smaller, simple mean differences were compared as well as individual measurements to determine the proportion of cases in which plaster measured as smallest. though small sample sizes were used in the present study, statistical power would not be improved by a larger sample because the variables are not dependent. results and discussion table 1 presents the results of the paired t-test comparing buccolingual measurements on tooth enamel to plaster and resin casts. none of the pairings demonstrated a statistically significant difference in measurement at the 0.05 (95%) confidence interval. these results support our predictions that both types of casts can be used in lieu of the original teeth when conducting odontometric analyses, without significant error in measurement. table 2 reports the mean measurements for each material type. measurements of the enamel were slightly larger on average than either plaster or resin, though plaster casts (as predicted) had the smallest mean of the three. still, the differences between the overall means were minimal. enamel measured, on average, 0.035 mm larger than resin and 0.043 mm larger than plaster. in the raw data, there were only three cases (13%) in which one or more of the replicas (plaster or resin) and/or origifigure 1: plaster (left) and resin (right) casts of a first molar. 19 dental anthropology 2022 │ volume 35│ issue 01 nal tooth (enamel) measured exactly the same. interestingly, individal measurements of plaster casts were lowest in more than half the cases (52%), followed by enamel (22%), and resin (13%). therefore, while plaster replicas produced some of the smallest measurements they were not exclusively the smallest measurements. overall, despite measurable differences between individual teeth and in the combined sample, for all intents and purposes these measurements are identical. the primary limitations of this study are sample size and composition. while the overall collection was estimated at 600 individuals, only a small portion of the collection resides in the u.s. additionally, differential preservation, significant tooth wear, and other limiting variables in the roughly 60 individuals meant only 23 teeth were able to be measured. additionally, this sample was one of convenience because it was available and nearby to the university where the study took place; therefore, these teeth may not reflect dental crown variability that could impact measurement. similarly, as a modern human sample we are unable to conclude that such measurements are similarly accurate for other primate dentition, where there may be higher morphological variability. finally, as noted in the materials and methods section, only buccolingual crown dimensions were gathered. while it was easy to measure isolated teeth in this setting, we were unable to replicate in situ dentition (i.e., teeth seated in the maxilla and/or mandible). such measurements require a higher level of dexterity to measure because of potentially tight interproximal spacing. as such, there is always the possibility that heavier compression of the calipers on softer cast materials could have resulted in significant differences between measurements. given the minor differences between measurements, material choice can be determined by the researcher’s preference because both casting materials provide accurate measurements. the researchers found that plaster casts were generally easier to measure than either enamel or resin casts because resin is translucent and has a smooth surface texture (like dental enamel) while plaster is opaque and slightly textured. specifically, the texture of plaster makes it less likely that caliper tips slip during measurements. if cost is an issue, resins also tend to be more expensive than dental plasters. conclusions the results of this study provide solid support for the continued use of either plaster or resin dental casts as proxies for original teeth, when needed. future research might examine different tooth types, different primate and ancestral hominin species, and/or include mesiodistal measurements. the present study excluded incisors and premolars, therefore, additional research on measurement error rates for incisors or premolars could be examined to determine if the results were specific to canines and molars. additionally, wide variation in tooth morphology and size across primate and ancestral hominin species could produce issues with measurement that should be considered. references al-mulla, a.a., & murad, s.m. (2010). accuracy and measurements made on digital and study models (a comparative study). mustansiria dental journal, 7(1), 71-82. bowes, m., dear, w., close, e., & freer, t.j. (2017). tooth width measurement using the lythos digital scanner. australasian orthodontic journal, 33(1), 73-81. chee, w.w.l., & donovan, t.e. (1992). polyvinyl siloxane impression materials: a review of properties and techniques. journal of prosthetic dentistry, 68, 728-32. hillson, s., fitzgerald, c., & flinn, h. (2005). alternative dental measurements: proposals and relationships with other measurements. american journal of physical anthropology, 126, 413 426. hollinger, j.o., lorton, l., krantz, w.a., & connelly, m. (1984). a clinical and laboratory comparison of irreversible hydrocoloid impression techniques. journal of prosthetic dentistry, 51, 304-309. hunter, w.s., & priest, w.r. (1960). errors and discrepancies in measurement of tooth size. jourtable 1. paired t-test results comparing tooth enamel, plaster casts, and resin casts (* indicates statistical significance). table 2. mean measurements and proportions (n=23). material type n t p-value enamel-resin 23 0.8985 0.3787 enamel-plaster 23 1.0464 0.3068 plaster-resin 23 0.9751 0.3401 material type mean (in mm) proportion (in %) enamel 10.242 22 plaster 10.199 52 resin 10.207 13 20 dental anthropology 2022 │ volume 35│ issue 01 nal of dental research, 39, 405–408. junior, e.v.d.s., kreve, s., & carvalho, g.a.p.d. (2018). analysis of linear dimensional change of different materials used for casting dental models: plaster type 4, nanocomposites carbon nanostructures, polyurethane resin and epoxy resin. journal of dental health, oral disorders & therapy, 9(2), 200-205. keating, a.p., knox, j., bibb, r., & zhurov, a.i. (2008). a comparison of plaster, digital and reconstructed study model accuracy. journal of orthodontics, 35(3), 191-201. kelso, r.s., hulsey, b.i., & driscoll, k.r.d. (2020). dental molding compounds and casts: use in non-laboratory environments. dental anthropology, 33(1), 17-22. kieser, j.a. (1990). human adult odontometrics: the study of variation in adult tooth size. new york, ny: cambridge university press. kumar, a.a., phillip, a., kumar, s., rawat, a., priya, s., & kumaran, v. (2015). digital model as an alternative to plaster model in assessment of space analysis. journal of pharmacy and bioallied science, 7(s2), s465-469. pant, r., juszczyk, a.s., clark, r.k.f., & radford, d.r. (2008). long-term dimensional stability and reproduction of surface detail of four polyvinyl siloxane duplicating materials. journal of dentistry, 36(6), 456-461. reuschl, r.p., wieland, h., stiesch, m., wenzel, d., & dittmer, m.p. (2016). reliability and validity of measurements on digital study models and plaster models. european journal of orthodontics, 38(1), 22-26. sedda, m., casarotto, a., raustia, a., & borracchini, a. (2008). effect of storage time on the accuracy of cast made from different irreversible hydrocolloids. journal of contemporary dental practice, 9(4), 59-66. wilmott et al. 2013.7 56 an 1837 pamphlet by saunders entitled “the teeth: a test of age” (considered with reference to the factory children) was one of the earliest uses of age estimation from eruption of teeth (miles 1963). this stated that if the third molar was present in the mouth (i.e. the first permanent molar m1, behind the deciduous molars), the child was likely to be 9 years of age. the accuracy of estimating age from tooth formation has been well documented, however, the accuracy of estimating age from alveolar or partly erupted or the clinical presence of a tooth in the oral cavity is unknown. estimating age from a partially erupted tooth is useful if root stage cannot be visualised or has been damaged. the aim of this study was to assess the accuracy of estimated age using several methods that provide mean/median age of tooth eruption levels. material and methods the sample was panoramic dental radiographs of 946 healthy children of known age attending a dental teaching hospital. subjects include at least 30 boys and 30 girls of each year of age from 3 to 16 (489 boys, 457 girls, mean age 9.80, age 3.00-16.99). each year age group was made up similar numbers of children from bangladeshi and white ethnic origin. panoramic radiographs were taken with consent in the course of diagnosis and treatment in paediatric dentistry and orthodontics. this is the same sample used to test dental age estimation methods by maber et al. (2006), liversidge et al. (2010) and alqahtani et al. (2014). eruption levels of seven mandibular teeth (excluding the third molar) on the left side were assessed by the first author. eruption levels were defined as developing tooth within bone, cusp tips at or just above the alveolar bone level (ae), cusp tips considerably above the alveolar bone level but not fully erupted (pe), fully erupted. eruption levels and root fractions are illustrated in figure 1. intra-observer reliability of assessing eruption level was calculated from duplicate scoring of 20 radiographs (140 teeth) yielding a kappa value of 0.96. tooth formation of seven mandibular teeth on the left side were assessed using tooth stages of moorrees et al. (1963) as part of a previous study (maber et al., 2006). accuracy of estimating age from eruption levels of mandibular teeth sheryl e. wilmott 1 , mark p. hector 2 , helen m. liversidge 1 1 queen mary university of london, barts and the london school of medicine and dentistry, institute of dentistry, turner street, london, united kingdom e1 2ad. 2 school of dentistry, university of dundee park place, dundee, scotland, dd1 4hn keywords: age estimation, alveolar eruption, permanent teeth abstract little is documented on the accuracy of estimating age from alveolar eruption (ae) or partial eruption (pe). the aim of this study was to compare the accuracy of age estimation from eruption levels. methods tested were gleiser and hunt (1955), garn et al. (1958), ando et al. (1965), haavikko (1970) and clinical eruption from smith et al. (1998). the sample was 946 panoramic dental radiographs from children aged 3-16 years. left mandibular teeth (excluding third molar) were assessed for eruption level (ae and pe) and root quarters. methods, teeth and eruption levels were deemed to be accurate if the average difference between estimated and chronological ages was not significant to zero using a t-test (p>0.05). results show that early erupting permanent teeth were fairly good at estimating age, although there was considerable age variation in eruption. haavikko incisors and molars at ae and haavikko and smith central incisor and second molar at pe estimated age accurately. root stage of erupting teeth estimated age more accurately than eruption level using haavikko. these findings suggest that erupting permanent mandibular teeth can be helpful in estimating age. correspondence to: dr. helen liversidge institute of dentistry turner street, london, united kingdom e1 2ad email: h.m.liversidge@qmul.ac.uk 57 the number of erupting teeth (ae and/or pe) on the left side of the mandible within an individual was counted. age was estimated if a tooth was at ae or pe, using glesier and hunt (1955), garn et al. (1958), ando et al. (1965) and haavikko (1970). if a tooth was partially erupted, age was also estimated from haavikko (1970) and smith et al. (1998). these values are shown in table 1. values for ando et al. (1965) were calculated in liversidge (2003) and contain an error m1 in boys. the raw data show that 60% of the youngest age category had reached ae. chronological age was subtracted from estimated age by tooth type and eruption level and the difference fig. 1. eruption levels and root fraction stages used in this study. a molar is shown at stages ae (alveolar eruption) and pe (partial eruption). root fractions are from haavikko (1970). tooth sex gleiser +hunt garn ando haavikko haavikko smith ae ae ae ae pe pe i1 girls 6.30 5.8 6.2 6.15 boys 6.28 5.9 6.3 6.26 i2 girls 7.13 6.5 6.8 7.24 boys 7.14 6.9 7.3 7.47 c girls 9.24 8.8 9.2 9.81 boys 9.54 9.8 10.4 10.71 p1 girls 9.7 9.59 9.1 9.6 10.45 boys 10.1 9.61 9.6 10.3 10.89 p2 girls 10.3 10.46 9.2 10.1 11.62 boys 11.1 10.54 10.3 11.1 11.96 m1 girls 5.1 5.7 5.0 6.3 6.27 boys 5.4 5.8 5.3 6.3 6.32 m2 girls 10.7 10.86 9.9 11.4 11.58 boys 11.2 10.98 10.8 12.2 12.06 1methods include mean age from gleiser and hunt (1955), garn et al. (1958), mean age calculated from ando et al. (1965) tabulated in liversidge (2003), median age from haavikko (1970) and mean age of clinical emergence from smith et al. (1998). bold values estimated age with no average bias (difference between dental age and chronological age not significant to zero). table 1. methods of age estimation from alveolar (ae) and partial (pe) stages of eruption of mandibular teeth used in this study1 58 compared to zero using a t-test with a significance level of p<0.05. a method, tooth or eruption level was considered accurate if the difference was not significant to zero. the difference between chronological and estimated age for teeth at ae and pe was also split by root fractions and compared to zero if n>10 per tooth stage. results the number of erupting teeth (ae and/or pe) in the left side of the mandible within an individual ranged from zero to four. just over half of this large sample (52%) had one or more erupting teeth. this is a reflection of the age range of the sample with most of the youngest individuals having no permanent teeth erupted and most of the older individuals having all seven permanent teeth erupted. the most frequent number of erupting teeth was one erupting tooth and only a small percentage of the sample had three or four erupting teeth. accuracy of estimating age from eruption levels showed that generally, early erupting teeth performed better than late erupting teeth. the difference between estimated and chronological age using the methods tested in this study for individual teeth are shown in table 2. the difference for m1 at ae using gleiser and hunt was not significant to zero. the two premolars using garn also estimated age accurately. no tooth using ando performed well. alveolar eruption of incisors and molars and partial eruption of i1 and m2 using haavikko and smith estimated age accurately. most tooth types underestimated age with the canine and premolars considerably under-estimating age at both eruption levels. fig. 2. scatterplot of estimated age using garn alveolar eruption and chronological age in years. 59 method eruption level tooth n mean difference sd p value gleiser+hunt ae m1 106 0.04 0.78 0.62 garn ae p1 46 -0.32 1.36 0.11 ae p2 39 -0.28 1.30 0.19 ae m1 109 0.55 0.79 0.00** ae m2 115 0.58 1.25 0.00** ando ae i1 59 0.57 0.68 0.00** ae i2 48 0.28 0.84 0.03* ae c 36 -0.91 1.10 0.00** ae p1 46 -0.69 1.32 0.00** ae p2 39 -0.42 1.29 0.05* ae m2 115 0.56 1.24 0.00** haavikko ae i1 59 0.13 0.68 0.14 ae i2 48 -0.16 0.86 0.20 ae c 36 -1.10 1.16 0.00** ae p1 46 -0.86 1.38 0.00** ae p2 39 -1.22 1.35 0.00** ae m1 109 -0.02 0.79 0.74 ae m2 115 -0.01 1.29 0.91 haavikko pe i1 36 -0.16 0.80 0.24 pe i2 39 -0.77 1.02 0.00** pe c 54 -1.35 1.46 0.00** pe p1 54 -1.54 1.46 0.00** pe p2 42 -1.78 1.92 0.00** pe m1 50 0.29 0.89 0.02* pe m2 42 0.02 1.39 0.92 smith pe i1 36 -0.21 0.80 0.13 pe i2 39 -0.45 1.00 0.00** pe c 54 -0.95 1.59 0.00** pe p1 54 -1.12 1.82 0.00** pe p2 42 -0.87 2.02 0.01** pe m1 50 0.30 0.88 0.02* pe m2 42 0.05 1.36 0.82 1ae and pe for individual teeth, * p<0.05, ** p<0.01. mean difference = estimated age minus chronological age in years. table 2. accuracy of estimating age from alveolar eruption (ae) and partial eruption (pe) using methods of gleiser and hunt, garn, ando and haavikko1, and smith 60 standard deviation values were high for most teeth ranging from 0.68 to just over 2 years. the difference between estimated age using garn and chronological age is plotted against chronological age in figure 2. this shows the early (first molar) and late phases of erupting teeth (premolars and second molar) and the age variation for each phase. the zero line indicates individuals whose teeth erupt at average age. age is overestimated for individuals whose teeth are advanced in eruption and underestimated for individuals whose teeth are delayed in eruption. further analyses by haavikko tooth stage are shown table 3 with only combinations of root fraction and eruption level with differences not significantly different to zero reported. for both incisors at ae and root stage r1/2 haavikko and r3/4 ando estimated age accurately. haavikko estimated age accurately (not significant to zero) if m1 was at ae and r1/4, but if root stage was r1/2 then garn estimated age accurately. two teeth estimated age accurately at pe (haavikko): the canine and m2 at r3/4. if m2 was ae and r1/2, haaviko estimated age accurately. the results of accuracy comparing tooth stage and eruption level using haavikko root fractions for teeth at ae and pe are shown in table 4. there were four combinations of eruption level and tooth stage that accurately estimated age using haavikko (i1 at ae and r1/2, m1 at ae and r1/4, m2 at ae and r1/2 and m2 at pe and r3/4). for all these combinations, the estimated age from root stage was closer to chronological age than estimated age from eruption level. standard variation for m2 stages were considerably greater than earlier erupting teeth. discussion tooth eruption has long been thought to be more variable than tooth formation and therefore less accurate at estimating age. our results show that alveolar eruption and partial eruption (including gingival emergence into the oral cavity) of permanent mandibular teeth can be used to estimate age in the immature dentition when root stage cannot be seen or has been damaged. alveolar eruption of early erupting permanent teeth ( i1, i2 and m1) as well as both ae and pe eruption levels of m2 can estimate age accurately. the finding that gleiser and hunt and haavikko values of m1 ae could accurately estimate age suggests that there has been no secular change in the eruption process of this tooth. the use of gingival eruption of individual tooth stage eruption method n mean diff sd p value i1 r1/2 ae haavikko 25 0.12 0.66 0.38 r3/4 ae ando 10 -0.03 0.57 0.86 i2 r1/2 ae haavikko 25 0.09 0.73 0.53 r3/4 ae ando 14 -0.18 0.68 0.35 r3/4 pe smith 20 -0.06 0.55 0.65 c r3/4 pe haavikko 14 -0.44 1.19 0.19 r3/4 pe smith 14 -0.03 1.21 0.94 p1 r3/4 pe smith 24 -0.41 1.13 0.09 p2 r3/4 pe smith 15 0.16 1.20 0.61 m1 r1/4 ae haavikko 77 0.12 0.73 0.15 r1/2 ae garn 28 0.10 0.73 0.46 m2 r1/2 ae haavikko 41 -0.30 1.04 0.07 r3/4 pe haavikko 25 0.20 1.12 0.38 r3/4 pe smith 25 0.19 1.05 0.38 table 3. individual haavikko root stages fractions and eruption levels where the average difference between estimated and chronological ages was not significantly different to zero (mean difference in years, sd standard deviation in years) 61 teeth to estimate age should be interpreted as a minimum age. the position of the cusp tips of a recently erupted tooth in the oral cavity relative to the occlusal level is not well documented and is influenced by local factors and tooth type. molars probably erupt closer to the occlusal level than later erupting premolars and canines. the strength of this study was the large sample age range with sufficient individuals prior to ae of m1 as well as sufficient older individuals. these older children, however, were drawn from orthodontic clinics and several individuals were excluded because they appeared to have crowding of teeth that prevented full eruption. limitations of this study include the definition of partial eruption. dean (2007) defined erupted stage more carefully with early and late eruption with cusp tips at/below the maximum bulbosity of the adjacent crown. assessing the process of tooth eruption into our discrete stages appeared to have adequate reproducibility. further research is needed to assess if our partial eruption level is equivalent to clinical emergence. conclusions the eruption of mandibular permanent teeth can play a role in estimating age. accuracy is higher using early erupting permanent teeth i (m1 and incisors) to estimate age compared to later erupting teeth. gleiser and hunt for m1 ae and haavikko i1, i2 and m1 and m2 ae and i1, m2 at pe are recommended to estimate age. if a tooth is erupting and root stage can be assessed, accuracy is higher using root stage. acknowledgements the first author received funding from barts and the london school of medicine and dentistry for a summer vacation studentship prior to completing her dental degree. literature cited alqahtani sj, hector mp, liversidge hm. 2014. accuracy of dental age estimation charts: schour and massler, ubelaker and the london atlas. am j phys anthropol 154:70-78. ando s, aizawa k, nakashima t, shinbo k, sanka y, kiyokawa k, oshima s. 1965. studies o n t h e consecutive survey of succedaneous and permanent dentition in the japanese children. i: eruption processes of permanent teeth. j nihon univ school dent 7:141–181. dean mc. 2007. a radiographic and histological study of modern human lower first permanent molar root growth during the supraosseous eruptive phase. j hum evol 53:635-46. garn, sm lewis ab. 1957. relationship between the sequence of calcification and the sequence of eruption of the mandibular molar and premolar teeth. j dent res 36:992-995. garn sm, lewis ab, koski k, polacheck dl. 1958. the sex difference in tooth calcification. j dent res 37:561–7. gleiser i, hunt ee. 1955. the permanent mandibu lar first molar: its calcification, eruption and de cay. am j phys anthropol 13:253–283. tooth n tooth stage eruption level estimated age method mean difference sd i1 25 r1/2 ae eruption 0.12 0.66 25 r1/2 ae tooth stage -0.03 0.68 m1 77 r1/4 ae eruption 0.12 0.73 77 r1/4 ae tooth stage 0.06 0.74 m2 41 r1/2 ae eruption -0.31 1.04 41 r1/2 ae tooth stage 0.03 1.27 m2 25 r3/4 pe eruption 0.20 1.12 25 r3/4 pe tooth stage 0.04 1.25 table 4. a comparison of accuracy estimating age from eruption level and tooth stage using haavikko1 1there were four combinations of eruption level and tooth stage that accurately estimated age using haavikko (i1 at ae and r1/2, m1 at ae and r1/4, m2 at ae and r1/2 and m2 at pe and r3/4). for all these combinations, the estimated age from the root stage was closer to chronological age than estimated age from eruption level. 62 haavikko k. 1970. the formation and the alveolar and clinical eruption of the permanent teeth: an orthopantomographic study. proc finn dent soc 66:103–170. hassanali j, odhiambo jw. 1982. estimation of calendar age from eruption times of perma nent teeth in kenyan africans and asians. ann hum biol 9:175-177. liversidge hm. 2003. worldwide variation in hu man dental development. in: thompson jl, nel son a, krovitz g, editors. growth and develop ment in the genus homo. cambridge: cam bridge university press. p 73–113. liversidge hm, smith bh, maber m. 2010. bias and accuracy of age estimation using developing teeth in 946 children. am j phy anthropol 143:545-554. maber m, liversidge hm, hector mp. 2006. accu racy of age estimation of radiographic methods using developing teeth. forensic sci intl 159:s68 573. miles aew. 1963, dentition in the estimation of age. j dent res 42:255-63. moorrees cfa, fanning ea, hunt ee. 1963. age variation of formation stages for ten permanent teeth. j dent res 42:1490–1502. smith jm, smith rn, brook ah, elcock c. 1998. timing of permanent tooth eruption in london school children. in: mayall jt, heikkinen t, edi tors. dental morphology '98. oulu, finland: oulu university press. p 187-191. ioannou et al. 2017.3 25 dental anthropology 2017 │ volume 30 │ issue 01 keywords: congenital syphilis, disrupted amelogenesis, severe hypoplasia, tooth morphology abstract specific dental abnormalities are considered pathognomonic of congenital syphilis (cs); however, european physicians recognized their variation during the late 19th to mid 20th centuries. observations of syphilis-related dental abnormalities in american individuals from similar time periods are made to determine types of variation among the american population. from a survey of the smithsonian institution’s national museum of natural history anatomical human skeletal collection, five individuals demonstrated dental characteristics consistent with cs (p00011r, p219398, p000707, p000679, and p000161). hutchinson’s three categories of dental anomalies were used to describe variations among syphilitic individuals. previously identified pathological dental characteristics related to cs were present in the analyzed individuals. p00011r, 24-year-old black female, has a maxillary right moon’s molar. p219398, approximately 20-year-old black female, has hutchinson’s incisors and fournier’s molars. p000707, 26-year-old black male, displays severe hypoplasia on all incisors, canines and maxillary first molars. p000679, 33-year-old black female has “screwdriver” shaped maxillary central incisors, altered occlusal morphology of first maxillary molars and hypoplasia. p000161, 45-year-old black female, demonstrates severe hypoplasia on incisors and canines (molars lost). “classic” dental characteristics of cs are not ubiquitous to all identified cases. this study exemplifies that dental anomalies associated with cs do not all have to be present for diagnosis. although other causes for some of these anomalies are possible, observations in these five cases are most consistent with cs. five cases of dental anomalies attributable to congenital syphilis from early 20 th century american anatomical collections stella ioannou 1 *, david hunt 2 , and maciej henneberg 1 1 biological anthropology and comparative anatomy research unit, adelaide medical school, the university of adelaide, adelaide, south australia, 5005 2 department of anthropology, national museum of natural history, smithsonian institution, washington, dc, 20013-7012 prior to the introduction of penicillin in the 1940s, syphilis was a public health problem in the united states (lancet, 1930; lancet, 1937a). the prevalence of syphilis in the united states at that time is difficult to determine, as data collection for syphilis by state health departments did not begin until the early 20th century, and the venereal disease division of the u.s. public health service was not created until 1918 (nakashima et al., 1996). to control venereal disease, various states implemented programs (free treatment, and clinics that offered free, pay, and part pay clinics) (lancet, 1937a), and legislation (marital examination law and prenatal law) (lancet, 1917; prebble, 1938; lancet, 1940; deporte, 1941). in cases of medical intervention, mercury was used to treat congenital syphilis in the 19th and early 20th centuries throughout the united states (conrad and mccann, 1922; cole et al., 1929; scheer and fraser, 1930; cole et al., 1933; chargin and saunders, 1939). treatments of syphilis also included chemotherapies of arsenic and bismuth compounds (lee, 1878; cole et al., 1929; eller and maloney, 1929). the chemotherapies most favored in the treatment of congenital syphilis included mercury, arsphenamine and potassium iodide (united states. public health service. division of venereal diseases, 1930). the effectiveness of mercury as a treatment for syphilis has been questioned (miller, 1858: weatherill, 1833); although, the treatment remained popular with some physicians. in some cases, syphilitic lesions completely healed and patients became seronegative (wakerlin, 1934). in syphilitic women treated with mercury during their pregnancy, 91.5% were efficient in completing their pregnancies successfully by live birth, while 47.6% non-treated women experienced fetal death (united states. public health service. division of venereal diseases, 1930). mercury and its compounds were seen to *correspondence to: stella ioannou the university of adelaide adelaide 5005, south australia, australia email: stelzy_25@hotmail.com 26 dental anthropology 2017 │ volume 30 │ issue 01 have antibacterial properties that actually reduced, or cured infections with treponema pallidum (smith, 1844; hare, 1858; warner, 1881; wakerlin, 1934). despite their possible curative effects on syphilis, mercurial treatments yield serious side effects including scarlatiniform rashes, stomatitis, pyrexia, bleeding of the rectum, and death in some cases (chopping, 1899; french, 1909). therefore, the use of mercury was abandoned later in the 20th century when other effective forms of treatment (i.e., penicillin) became available and mercuric treatments were dropped from clinical practice. in paleopathology, the diagnosis of congenital syphilis (cs) is based on skeletal and dental signs. however, when skeletal signs are not present specific dental abnormalities caused by a disturbance in odontogenesis are associated with the disease (hillson et al., 1998). signs include hutchinson’s crescentic notched or screwdriver incisors (hutchinson, 1859; 1887), moon’s dome-shaped molar (moon, 1884), and fournier’s molars of “upset appearance” (bouleversée d'aspect) (fournier, 1886:84). these changes occur when odontogenesis is affected during the early stage of the disease. during the 19th century, jonathan hutchinson, was the first to note that syphilitic treatments containing mercury also affected dental development, disrupting amelogenesis. hutchinson described that these mercuryinduced dental malformations were significantly different from those caused by congenital syphilis alone, and in some cases, patients exposed to a treatment regimen involving mercury could manifest dental signs associated with the disease and treatment (hutchinson, 1888; moon, 1884; summarized in ioannou et al., 2015, 2016). it should be noted that 1030% of patients clinically diagnosed with congenital syphilis do not manifest changes associated with disturbed odontogenesis (švejda, 1952; lipski and przylipiak, 1959). it is clear that these inconsistencies caused confusion among physicians in the past (hutchinson, 1878) and with diagnoses in both clinical and paleopathological settings. during late 19th and early 20th centuries, various institutions produced collections of skeletons for future research purposes. these collections included skeletons of individuals who suffered from various diseases including treponemal diseases. today such collections provide hard evidence of the disease and its treatments, independent of government records and the literature. for some individual skeletons, there is medical documentation stating the cause of death, while others have been given differential diagnosis based on the skeletal evidence by the curator. such diagnoses were based on paleopathological knowledge of the curator at the time. while previous studies have focused on “typical” dental characteristics associated with congenital syphilis, this paper will also assess the possibility of some of the dental anomalies being from the medical treatments. therefore, the aims of this paper are: (1) to describe the variation and similarities in dental abnormalities associated with congenital syphilis in individuals either medically diagnosed with the disease or who were posthumously diagnosed by skeletal pathological conditions or dental anomalies to have been afflicted with congenital syphilis, and (2) to evaluate whether there are any indications of dental features that could be the result of treatments for congenital syphilis. differential diagnoses of other diseases or genetic conditions that could have effects on dental characteristics are reviewed, including tuberculosis, leprosy, amelogenesis imperfecta, rickets, fluorosis, and some of the chemicals used to treat these diseases are also considered, such as mercury, arsenic, bismuth, lead and cadmium. materials and methods as stated above, 10-30% of patients clinically diagnosed with congenital syphilis do not manifest dental anomalies (švejda, 1952; lipski and przylipiak, 1959). to assess the range of expression of the dental anomalies attributed to congenital syphilis, those conditions as described by jonathan hutchinson (1859, 1863, 1878, 1887, 1888), henry moon (1877, 1884), alfred fournier (1886), and hillson et al. (1998) are used as the criteria for the cases observed here to evaluate the likelihood of congenital syphilis in the anatomical collections and to see if comparable dental abnormalities are present. the criteria are reviewed and described by ioannou et al. (2016). a review of dentition in the early 20th century robert j. terry anatomical skeletal collection and cadaver room skeletons from the howard university medical school was made at the smithsonian national museum of natural history (nmnh) in washington dc. the survey focused on individuals listed as having pathological conditions related to the following: congenital syphilis, treponemal disease, lues disease, syphilis, tuberculosis, and rickets. these pathological identifications came from death certificate records, reports from the morgue records, or diagnoses made by observations of the cadavers or the skeletal elements in dissection or after skeletonization. some of the observations made by curators were independent from the cause of death of these individuals. out of 38 individuals that were narrowed down from the initial survey, five individuals exhibited various dental malformations consistent with those in patients diagnosed with congenital syphilis (excel file with data is available from si upon request). the five individuals were p00011r, p219398, p000707, 27 dental anthropology 2017 │ volume 30 │ issue 01 p000679 and p000161, of which only p00011r was clinically diagnosed with congenital syphilis while living. the dentition of these individuals was analyzed to document the types and range of malformations in tooth morphology. since human variation and their effects from disease are individualistic and often do not present the “typical” pathological manifestations of a particular disease. to evaluate the possibility of mercury treatment of any of these subjects, portable x-ray fluorescence (pxrf) spectrometry was conducted to determine whether mercury could be detected in the enamel and bone in each of the individuals. dental malformation criteria for evaluation of treponemal disease hutchinson (1859, 1863, 1878, 1887, 1888) recognized that dental malformations observed in children with congenital syphilis varied so considerably that he deemed it necessary to create various categories to distinguish kinds of anomalies in dental formation. his three categories of dental malformations were syphilitic teeth, mercurial teeth, and syphiliticmercurial teeth. in the syphilitic category, the maxillary central incisors are the “test teeth”. the central incisors can appear “peg like” or screwdriver in shape, are dwarfed and display a crescentic notch on the incisal edge (hutchinson’s incisors). some of these features can also be observed in the maxillary lateral incisors and mandibular incisors (hutchinson, 1887; hillson et al., 1998). other characteristics within the syphilitic category include malformations observed in the first permanent molars (hutchinson, 1887) labeled as moon’s molar and fournier’s molars. moon’s molar is “smaller than usual and dome-shaped” (moon, 1877), while fournier’s molars either have several nodules and tubercles or have a flat surface (fournier, 1886). both varieties of fournier’s molars have a clear demarcation between healthy and diseased enamel. mercurial teeth demonstrate severe enamel hypoplasia, caused by treatments containing mercury. the first permanent molars are the “test teeth”. the enamel is deficient and appears rugged, pitted, and dirty with a honeycomb appearance (hutchinson, 1878; ioannou et al., 2016). dentine is affected in severe cases with the appearance of multiple spines or tubercles. the entire occlusal surface or a central area can be affected. incisors and canines are also affected with severe linear enamel hypoplasia that crosses these anterior teeth at the same level. the enamel between the linear enamel hypoplasia and the tip of the crown is deficient (hutchinson, 1878), and pitting hypoplasia is also common. premolars in most cases appear normal. however, the characteristic notch observed in syphilitic incisors is not mimicked in mercurial conditions only (hutchinson, 1878). syphilitic-mercurial teeth demonstrate a combination of both syphilitic and mercurial dental malformations (hutchinson, 1878; moon, 1884; ioannou et al., 2016). the upper central incisors can have a peg-like or screw-driver shape (outline), the incisal edges appear characteristically notched, and any part of the enamel surface can be hypoplastic, pitted and discolored. the first permanent molars can show an absence of enamel on the occlusal surface of the crown but have healthy enamel on its sides (hutchinson, 1878). results terry collection p00011r (fig. 1) is an african american female, born in 1918 and died in 1942, at 24 years old. the primary cause of death was attributed to lobar pneumonia, but was clinically diagnosed with congenital syphilis in 1930 and was subsequently institutionalized until her death, 11 years and 2 months later. this is the only individual that was diagnosed with congenital syphilis during the life of the individual. all maxillary incisors and left maxillary canine were lost many years before death (fig. 1a). the first right upper molar has a clearly narrowed occlusal surface with pitting hypoplasia resembling a dome shape (moon’s molar) (fig. 1b & 1c). the left first upper molar has a narrowed occlusal surface, and is largely destroyed by dental caries. all the premolars and right canine have normal morphology. the second and third permanent molars have normal molar morphology. the left third molar has a single carious lesion on the disto-buccal aspect. upper alveolar process shows periodontal changes on both sides. the mandibular teeth present include the left and right lateral incisors, left canine, left and right first premolars, left second premolar and left and right second and third permanent molars. the lateral incisors appear peg like in shape (fig. 1d & 1e). both first permanent molars were lost many years before death, and the alveoli are completely healed (fig. 1f). the occlusal surface of the left second premolar and second and third permanent molars are destroyed by caries. bone resorption suggests periodontal disease (fig. 1d & 1f). cranial morphology is normal, no ‘saddle nose’ is present, and the nasal cavity and palate are normal. the molars in p00011r are syphilitic. howard collection p219398 (fig. 2) is an african american female who died in 1903 in washington, dc with no recorded cause of death and was autopsied at howard university school of medicine. there is not a reported age at death, but dental and skeletal development indicators suggest this individual died between 20 and 25 years of age. previous evaluation 28 dental anthropology 2017 │ volume 30 │ issue 01 by researchers and curators identified the dental anomalies and considered them to be the product of congenital syphilis and this was noted in the smithsonian pathology files. all maxillary teeth are present, except the left second and third permanent molars. the maxillary central incisors are marked by rounded mesial and distal incisal edges. the labial aspects of the incisal one-third of both crowns have centrally located hypoplastic defects. on the right central incisor, this hypoplasia resulted in a smooth crescentic pit, while on the left central incisor there is irregular hypoplastic pitting in the same location (fig. 2a). multiple short lines of hypoplastic enamel are also apparent on the lingual surface of both teeth. the mesial and distal edges of the right and left lateral incisors are also rounded off, giving both teeth a peg-like shared crown. multiple pits are present on the lingual surface of both lateral incisors. the tips and lingual aspects of the canines display hypoplastic pitting. the occlusal surfaces of the first permanent molars have diminished areas compared to the dimensions of the rest of the crown (fig. 2b & 2c). there are also scattered hypoplastic pits and various areas of the occlusal surfaces have irregular grooves (fig. 2c). the molars resemble both types of fournier’s molars. the second right permanent molar has normal molar morphology. the left second molar was lost during life, as the alveolar bone has healed. the mandibular dentition is nearly complete. the left canine was lost post-mortem, while the alveolus of the lower left third molar is healed. the central incisors are affected by severe enamel hypoplasia and exposed dentine on the incisal one-fourth of the crown (fig. 2d). the morphology and enamel of all other teeth, except the first permanent molars, appears normal. the occlusal surfaces of the crowns of the first permanent molars are reduced in size and severely hypoplastic (fig. 2e & 2f). the cusps appear to be reduced in size and multiple tubercles are visible (fig. 2f). this appears similar to fournier’s nodule-type molar. the dentine is also exposed in places. the morphology of the second permanent molars appears normal, with the left demonstrating signs of crenulation. the entire crown of the third right permanent molar is missing with only the root present while the left was lost during life as indicated by figure 1. individual p00011r, 24yrs old female. (a) anterior view of maxilla: central and lateral incisors, and left canine missing. no saddle nose. (b) occlusal view: most teeth have normal morphology. carious destruction of the left first molar does not allow precise observation, but it seems that the crown has a narrow occlusal surface. (c) first right permanent molar has a narrow and reduced occlusal surface resembling moon’s molar. pitting is also present. (d) anterior view of the mandible. periodontal disease is evident. (e) loose anterior tooth of mandible; lateral right incisor. (f) occlusal view of mandible: no first molars, most likely lost to caries. 29 dental anthropology 2017 │ volume 30 │ issue 01 healed alveolar bone. the morphology of the alveolar bone suggests some periosteal inflammation was present at the time of death. the dental abnormalities in p219398 are most consistent with syphilitic malformations. terry collection p000707 (fig. 3) is an african american male, aged 26 years at the time of his death in 1929 in st. louis, missouri from pulmonary tuberculosis. previous evaluation by researchers and curators identified the dental anomalies and considered them to be the product of congenital syphilis and this was noted in the smithsonian pathology files. all permanent teeth, including the third molars, are present. the central incisors are marked by minor notches and isolated pits along the incisal edges. enamel adjacent to the incisal edge appears healthy with minor pitting, however, the middle third of the crown shows progressively more severe pitting hypoplasia that ends with extremely deep defects that likely penetrate the pulp cavity (fig. 3a). the cervical portion of the crowns appears normal. the left lateral incisor is affected by a similar progressively pitted enamel defect on the incisal third of the crown (fig. 3a). the incisal third of the right lateral incisor has been lost at a point where the pitting morphology appears like that observed in its left-side antimere. a similar enamel defect affects the left canine (fig. 3b). the enamel of the right canine appears to have broken off postmortem. the lingual surfaces of these anterior maxillary teeth are affected by irregular hypoplastic defects, demonstrating a mottled like appearance. the premolars have normal morphology. the occlusal two thirds of the crown of the first permanent molars are hypoplastic, with pitting hypoplasia and reduced surfaces in comparison to the other permanent molars present (fig. 3c). however, some normal groove patterns of the occlusal surfaces are preserved. minor pitting is present on the second and third permanent molars. the second left and third right permanent molars demonstrate crenulation. the alveolar bone suggests some periosteal inflammation was present. the mandibular dentition consists of all permanent teeth, except the left and right first molars. two thirds of all incisors and canines are affected by severe hypoplastic defects (fig. 3d). the left and right first molars were lost antemortem. the alveoli for the first molars are healed but not completely resorbed (fig. 3e). the second permanent molars and the left third permanent molars have normal molar morphology but demonstrate crenulation (fig. 3f). the third left molar appears larger than the second permanent molars. a supernumerary fourth molar is present on figure 2. p219398, 20yrs old female. (a) anterior view of maxilla: labial aspect of permanent central incisors. right incisor has thin enamel along incisal edge forming a crescentic pit. irregular pitting is noted in the same location on the left incisor. lateral incisors are peg-like in shape. (b) occlusal view of maxilla: occlusal surfaces of the first permanent molars are reduced and demonstrate scattered hypoplastic pits and irregular grooves. (c) occlusal view of the left first permanent molar of maxilla demonstrates pitting and grooves in enamel. the occlusal surface is also reduced. (d) anterior view of mandible: central incisors demonstrate enamel hypoplasia and exposed dentine on the 1/4 of the crown. note, the central and lateral incisors appear to be incorrectly inserted into mandible post mortem. (e) lateral view of right side of mandible: first permanent molar resembles that in the maxilla. (f) occlusal view of right mandibular first permanent molar: it has reduced surface, multiple tubercles and pitting hypoplasia. 30 dental anthropology 2017 │ volume 30 │ issue 01 the left side (ioannou & henneberg, 2016). it is smaller in size in comparison to the other molars and has normal molar morphology (fig. 3f). p000707 demonstrates dental signs that are suggestive of mercuric treatments. terry collection p000679 (fig. 4) is an african american female, who died of tuberculosis at 33 years of age in st. louis, missouri in 1928. previous evaluation by researchers and curators identified the dental anomalies and considered them to be the product of congenital syphilis and this was noted in the smithsonian pathology files. the maxillary dentition is complete, except for the left third molar. it is unclear whether the absence of this tooth was due to agenesis or antemortem tooth loss. the maxillary central incisors have narrowed incisal edges with rounded corners. located at the midcrown on the labial surface are hypoplastic defects that consist of an approximately oval-shaped area of thinner enamel, which is surrounded by pitting that extends distally to the one -third of the crown from the incisal edge (fig. 4a). shoveling is apparent on the lingual aspects, as is one linear hypoplastic line on the cervical third of the crowns (fig. 4b). the lateral incisors appear peg like in shape with round mesial and distal edges. a couple of isolated pits are evident on the right lateral incisor. one hypoplastic line runs at the same level on both lateral incisors on the labial aspect. the left canine has isolated pits on the tip of the crown. pits and grooves are present on the lingual aspect of the canines. pitting is on the occlusal surface and lingual aspect of the first premolars. the right second premolar has a deep groove on the lingual surface. maxillary first molars have occlusal surfaces that are reduced in size and have abnormal enamel formation (fig. 4c). there is a demarcation between diseased and healthy enamel by pitting hypoplasia (fig. 4d). the second molars and third right molar have normal morphology. the mandibular dentition is represented by a full set of anterior teeth from the left first premolar to the right first premolar. the right third molar and the left second molar are present. all other posterior teeth were lost antemortem as indicated by complete alveolar remodeling (fig. 4e). the incisors are marked by multiple notches on their incisal edges. shallow indistinct furrows are present about one-third the length of the crown (fig. 4f). isolated pits are present on the lateral incisors. part of the enamel on the labial figure 3. p000707, 26yrs old male. (a) anterior view of maxilla: incisal edges of the maxillary central incisors appear healthy with isolated pits. the middle third of the crown demonstrates progressively severe enamel hypoplasia. similar enamel hypoplasia is evident on the lateral incisors and canines. (b) lateral view of the left side of maxilla: the lateral incisor and canine display enamel defects similar to the central incisors. (c) occlusal view of upper right first permanent molar, note unusual configuration of enamel on the occlusal surface. two thirds of the occlusal surfaces of the first permanent molars are severely hypoplastic, although some normal groove patterns are preserved. (d) anterior view of the mandible: two thirds of all incisor and canines crowns are affected by severe hypoplastic defects. (e) occlusal view of mandible, note both first molars are missing. (f) close up of supernumerary fourth molar. note crenulation on occlusal surfaces of other molars. 31 dental anthropology 2017 │ volume 30 │ issue 01 surface of the left central incisor has broken off postmortem. the first premolars have isolated pits on their surfaces. all other remaining mandibular teeth have normal morphology. the dental defects in p000679 are comparable to hutchinson’s dental observations for cs and suggestive of mercurial teeth morphology. terry collection p000161 (fig. 5) is an african american female who was approximately 45 years of age at the time of death and added to the skeletal collection in 1925. no cause of death is recorded in the morgue records. previous evaluation by researchers and curators identified the dental anomalies and considered them to be the product of congenital syphilis and this was noted in the smithsonian pathology files. all maxillary teeth are present, except the right second premolar and the left first molar. the incisal margins of the central and lateral incisors are notched. the labial surfaces of crowns of anterior teeth have malformed enamel, featuring irregular pitting and a deep furrow located about one-third of the crown height proximal to the incisal edge (fig. 5a). a second furrow appears on the left central incisor on the cervical third of the crown. the furrows of the anterior teeth appear approximately at the same level. some enamel was lost postmortem on the cervical third of the right central incisor and parts of the mesial aspect of the left central incisor. numerous dark colored pits run horizontally along the middle third of the crown of the central incisors and the incisal third of the lateral incisors and tip of canines. (fig. 5a). similar pitting and linear hypoplastic defects occur on the lingual surfaces of these teeth (fig. 5b). the morphology of the premolars and other molars still present appears normal. a fragment of the occlusal surface of the right first permanent molar is marked by irregular enamel and pitting. a large carious lesion is present in the disto-lingual area of the right first permanent molar, while an interproximal carious lesion is evident towards the mesio-lingual end of the crown. the left first molar has been lost most likely due to dental caries. the alveolar bone has not healed completely, so it is possible the loss occurred shortly before death. the morphology of both second molars and third molars appears normal. on the palate anteriorly on the right side there is a circular bony depression surrounded by elevated bone. there is a large perforation on the right side of the palate. there is also some pitting in the palate that is more apparent near the right first permanent molar. the mandibular dentition consists of the left and right lateral incisors, canines, first and second premofigure 4. p000679, 33yrs old female. (a) hypoplastic defects on labial surface of central incisors. those that are in the incisal third of the crown are large and oval in shape and are centrally located with small-scattered pits. some other teeth also display pitting. (b) occlusal view of maxilla: occlusal surfaces of first permanent molars have abnormal formation of the enamel. (c) close up of upper right first molar. (d) palatine view of the right maxillary dentition: note demarcation between diseased and healthy enamel in the first permanent molar. (e) occlusal view of mandible. (f) anterior view of mandible: incisors are marked by multiple notches on their incisal edges while shallow indistinct furrows are present about one-third the height of the crown. 32 dental anthropology 2017 │ volume 30 │ issue 01 lars, second molars and the left third molar. the central incisors were lost post mortem, while both first molars and the right third molar were lost antemortem. the alveoli for both first molars are completely remodeled, but the alveolus for the left has been less remodeled than the right. the third right molar alveolus is healed. similar to the maxillary dentition, severe linear and pitted enamel hypoplastic defects are present on the lateral incisors and canines (fig. 5c). the multiple hypoplastic lines run along at the same level of the crown of these teeth on both labial and lingual surfaces (fig. 5c & 5d). the tops of the crowns of the first premolars appear hypoplastic. pitting and two small carious lesions are present on the occlusal surface of the left first premolar. the crowns of both second premolars appear normal. the abnormalities seen in the dentition of p000161 are consistent with hutchinson’s description of patients with cs and possibly some features suggestive of mercury effects. mercury testing using pxrf an exploratory, qualitative analysis using a portable x-ray fluorescence analyser (pxrf) was performed to see if any of the individuals above might have mercury or other chemical elements possibly related to treatment for cs and the cause of the dental abnormalities. the analysis was conducted using a bruker tracer iii-v handheld analyser on portions of hypoplastic enamel on the central and lateral incisors for all of the individuals, except individual p00011r, which lacked central incisors instead, a lateral incisor and canine were tested. the analysis was conducted with settings optimized for mercury (0.001” cu, 0.001” ti, 0.012” al filter at 40 kev/16 micro amps for 300 seconds, without vacuum). bone testing was done on the femur of the same individuals to test for contamination if high readings of any particular elements were found. no mercury was detected. the lack of mercury in these individuals most likely can be attributed to amounts of mercury that may be too minute for the instrument’s detection capabilities (see zuckerman, 2016:50 for discussion on mercury detection with pxrf). differential diagnosis diseases that interfere with odontogenesis and amelogenesis are considered for a differential diagnosis. figure 5. p000161, 45yrs old female.(a) severe hypoplastic enamel of the maxillary incisors and canines. incisal thirds of the central and lateral incisors’ and canines’ crowns are hypoplastic with deep furrows. dark colored pits run horizontally across the crowns. (b) occlusal view of maxilla: linear and pitting hypoplasia noted on the lingual surface of anterior teeth. (c) anterior view of mandible: severe linear and pitted enamel hypoplasia on the lateral incisors and canines. (d) lingual view of mandible: pitted and linear enamel hypoplasia evident on lateral incisors and canines corresponds to that on labial surface. 33 dental anthropology 2017 │ volume 30 │ issue 01 these include tuberculosis, leprosy, amelogenesis imperfecta, rickets and fluorosis, as well as elements that have been used as treatments or are known to affect tooth development such as mercury, arsenic, lead, bismuth, and cadmium. tuberculosis is a chronic disease that predominately affects the ribs, vertebrae, and the large joints of the body. in adult onset of tuberculosis, there would be no effect on the dentition. in cases of childhood tuberculosis, the most common dental abnormalities are associated with developmental stress linear enamel hypoplasia (dabernat and crubézy, 2010; bedić et al., 2015); carious lesions (formicola et al., 1987; hlavenková et al., 2015); and decreased enamel thickness (formicola et al., 1987). since dental signs observed in childhood tuberculosis do not resemble the dental abnormalities or the severity observed in the five cases, tuberculosis is not likely and would be ruled out as a differential diagnosis. leprosy is a chronic disease that affects the skin and peripheral nervous system with skeletal loss by resorption in the latter stages of the disease. it is a slow and progressive disease, signs of the disease can start to develop from six months to 30 years (world health organization. 2012). dental abnormalities that have been reported in skeletal cases with evidence of leprosy include linear enamel hypoplasia (boldsen, 2005) (which might be correlated to possible frailty in the individuals, rather than leprosy itself), and constriction of the roots of the upper permanent central incisors (leprogenic odontodysplaia) (roffey and tucker, 2012) that might be related to the resorption of the alveolus rather than development effects of dental formation (roberts 2011). these observations are not common or diagnostic of the disease. if a child were to be infected with leprosy, since its macroscopic expression would be long-term, it is assumed that the disease would not severely affect dental development, possibly only producing linear enamel hypoplasias from insults to development. it is unlikely that there would be the severity of dental pathology similar to those in the described cases here. since leprosy is predominately an adult disease, if in children it would not have the severe effects as seen in cs, therefore, leprosy is ruled out as a differential diagnosis. amelogenesis imperfecta (ai) is a hereditary condition characterized by enamel defects. phenotypic expression of the condition is caused by a disturbance in ameloblasts secretions producing hypoplasia, hypocalcification, hypomaturation and hypomaturation-hypoplasia with taurodontism (gadhia et al., 2012; prasad et al., 2016). amelogenesis imperfecta also manifests in enamel discoloration, enamel pitting, and thin enamel (kar et al., 2012; gerdolle et al., 2015; rogers et al., 2016). the prevalence of ai varies between populations from 43:10,000 in turkey to 1.25:10,000 in israel (gadhia et al., 2012). amelogenesis imperfecta is an unlikely differential diagnosis for the described cases since ai tends to affect amelogenesis in most all or all teeth – this is unlike congenital syphilis where only specific teeth are affected. rickets is a disorder caused by either a lack of vitamin d or phosphorus. these metabolic deficiencies affect tooth mineralization and bone development. rickets may cause some non-severe linear or pittingtype enamel hypoplasia and in cases discoloration and enamel opacities (zambrano et al., 2003; davitbeal et al., 2014). like ai, rickets more uniformly affects the teeth. therefore, with the severity of hypoplastic defects described and the specific tooth involvement, this is not consistent with rickets and their differential diagnosis can be ruled out. consumption of large amounts of fluoride can lead to fluorosis, and specifically in developing dentition will cause disturbance of amelogenesis. enamel will appear discolored (yellow to dark brown), demonstrate white opaque patches or lines, or pitted or mottled hypoplasia (sherwood, 2010; munñoz et al., 2013). similar to ai and rickets, fluorosis does not affect selected teeth, and its hypoplastic effects are less severe than those described in the five cases presented here. thus, the diagnosis of fluorosis is unlikely. mercury was used for medicinal purposes throughout the united states to treat syphilis and congenital syphilis (cole et al., 1929; united states. public health service. division of venereal diseases. 1930). mercury was administered in various forms but was most commonly injected intramuscularly or rubbed onto the skin. treatments containing mercury ranged from one and a half to fourteen grams of solution or ointment (cole et al., 1929; cole 1933). since some of the malformations observed in p000707, p000679 and p000161 could be suggestive of the mercurial or syphilitic-mercuric category set by hutchinson (1878) and moon (1884), it is possible that mercury might have caused the dental malformations. there is no proof that any of these individuals may have had treatments and the one clinically diagnosed case (p00011r), was diagnosed at an age that would have excluded the severe effects of dental malformation if mercury were administered after her diagnosis. arsenic was also used to treat syphilis/congenital syphilis; however, its effects on enamel development in children with congenital syphilis are limited. arsenical poisoning has been found to cause tooth sensitivity and tooth abrasion in children (sunny, 2013), but nothing in the way of severity of the anomalies caused by mercury. thus, the possibility of arsenic poisoning or treatment is an unlikely differential di34 dental anthropology 2017 │ volume 30 │ issue 01 agnosis. bismuth was introduced later than mercury and arsenic, and was used in conjunction with these to treat syphilis and congenital syphilis. bismuth was noted to cause pigmentation of gums and the enamel, most frequently seen on the labial surfaces of the lower and upper central incisors and in prolonged acute cases, loosening of the teeth (mccarthy and dexter 1935; dean, 1943). the common factor observed in bismuth poisoning is that the cervical portion of the incisors was the most constant location for pigmentation (mccarthy and dexter 1935; dean, 1943). we see none of this pigmentation, and these individuals would have been too young to have received bismuth treatments, thus, excluding this as a differential diagnosis. lead was considered a possible cause in dental development, but previous studies have not found lead to cause enamel abnormalities. high levels of lead only result in a decrease in microhardness of enamel (gerlach et al., 2002; youravong et al., 2005) coupled with increases in abrasion and discoloration (gil et al., 1996). normal enamel morphology has been observed in cases where high levels of lead were present (gerlach et al., 2002; youravong et al., 2005). cadmium, although not used to treat syphilis or congenital syphilis, is known to accumulate in enamel; however, its effects on enamel development are limited in the literature. wilson and deeds (1939) noted that cadmium toxicity caused bleached white enamel discoloration. since that is not observed in the discussed individuals, cadmium is unlikely diagnosis. discussion and conclusions syphilis was a disease that caused serious problems in the united states during the late 19th and early 20th centuries, with various measures taken to control its spread (lancet, 1930; lancet, 1937a; lancet, 1917; prebble, 1938; deporte, 1941). while various programs and legislations were initiated, treatments (including mercury) were of primary importance to reduce prevalence rates (lancet, 1921; lancet, 1937a; lancet, 1939). even though mercury was known to produce side effects, similarly to other chemotherapies (arsenic and bismuth), it was still considered the most effective, being used on its own or in combination with other pharmaceuticals (lancet, 1937b). however, the healing nature of mercury has also been called into question due to non-systematic recording of treatments and outcomes in the 19th century, as well as misdiagnosis of the decades-long quiescence of the disease as “cured” (zuckerman, 2016). individual p00011r was diagnosed in life with congenital syphilis. the only detectable manifestations of this diagnosed condition are visible in her teeth. while some of her teeth are missing, those that are present, especially the first permanent molars, are highly consistent with the anomalous condition found in cases of congenital syphilis. the domeshaped and reduced occlusal surface of her first permanent molars is obviously a consequence of developmental disruption caused by congenital syphilis. they resemble those described by moon (1884), but due to developmental variability, are not not identical to the description. while congenital syphilis was diagnosed and recorded only in this one individual, the other four individuals display dental changes that fit the broad range of changes described by hutchinson (1859, 1863, 1878, 1887, 1888), and moon (1877, 1884). individual p219398 demonstrates tooth morphology that fits the syphilitic category described hutchinson. the right central incisor displays a crescentic groove towards the incisal edge. hutchinson (1863) describes that once this thin enamel has broken off, the characteristic notch is present. the hypoplastic lesions in the dentition of individuals p000707 and p000161 are of significant severity. in p000707, enamel malformations in the maxillary central incisors begin approximately 2mm from the incisal edge and a normal groove pattern is visible on the very occlusal surface of the first permanent molars, indicating malformation in amelogenesis in the first months of the infant’s life. the lateral incisors and canines demonstrate similar enamel defects but are located at different crown heights that correspond to the differences in the timing of formation of these teeth. crown development of first permanent molars begins perinatally, permanent central incisors begin to form at approximately 3-4 months of age, lateral incisors at approximately 10-12 months and canines at six months (nelson & ash, 2010). the crown of first molars is completed at about 2.5-3 years of age, both incisors at approximately 4-5 years of age, and at about 6-7 years of age for canines (nelson & ash, 2010). judging from the position of hypoplastic defects (reflecting the mercurial category features by hutchinson) these changes would occur at about 2.0-2.5 years of age. the pathological changes in the dentition of individual p000161 follow similar interpretation for development and hypoplastic events similarly to individual p000707. however, hypoplastic defects are positioned somewhat earlier in the individual’s life and ceased later than in individual p000707. the severe enamel abnormalities observed in individual p000161 are changes that are more similar to the examples of the mercurial category as described by hutchinson. but as presented above, no record of this treatment can be attributed to this individual. individual p000679 has enamel defects of the maxillary central incisors that are much like the mercurial 35 dental anthropology 2017 │ volume 30 │ issue 01 category described by hutchinson. whatever disturbances caused the anomalous formations of the teeth would have to have started not long after birth or from treatment to the mother the abnormal enamel occurs much closer to the incisal margin than that seen in either individual p000707 or p000161. but again, there is no record of this treatment attributable to this individual. in skeletal collections when medical information is not available, paleopathologists make differential diagnoses from the skeletal/dental evidence using the knowledge available at that time. during the turn of the last century and into the 20th century r. terry, d.s. lamb, a. hrdlicka, t.d. stewart and jl angel made diagnoses of pathological conditions and anomalies on the anatomical and archaeological remains using their familiarity with the pathological understanding from their medical experience, and their knowledge of medical treatment for various diseases. for the individuals studied here, notations of the dental and skeletal observations related to or attributable to “treponemal disease” were made in the smithsonian records from these scientists based on their observations and knowledge of the disease. in these records, differential diagnoses were often not listed, and thus in some cases, the labeling of a disease may have been from the observations, not from the clinical record of cause of death. from what has been observed in this study, these individuals encompass a range of variation in the dental abnormalities that have occurred in syphilitic patients. the findings of this study provide examples of this range of manifestations, discussing the basis for the malformations, and provide additional insight into identifying cs in future studies. acknowledgments the authors would like to thank dr. rhonda coolidge for her analysis and report using the pxrf. the instrument was made available by the smithsonian anthropology repatriation osteology laboratory. we also acknowledge the monumental effort of martin coolidge in acquiring the death certificates for the majority of the terry collection individuals – which allowed for determination of diagnosed congenital syphilis in p00011r. the first author would like to acknowledge the australian government research training program scholarship. literature cited bedić, ž., vyroubal, v., tkalčec, t., šlaus, m. 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(2013). oral health of the arsenic exposed and non-exposed children in bangladesh. city dental college journal, 10, 5-8. švejda, j. (1952). zmeny na zubech pri kongenitalni syfilis. cesk stomatology, 52, 321–341. united states. public health service. division of venereal diseases. (1930). congenital syphilis : abstracts secured in the compilation of "venereal disease information" and on file in the division of venereal diseases ; compilation no .2, (rev. june, 1930) ; issued by the united states public health service for the use in its cooperative work with the state health departments / taliaferro clark, assistant surgeon general, chief, division of venereal diseases. washington, dc: united states government printing office. warner, f. (1881). east london hospital for children: cases of congential syphilis. lancet, 117, 173-174 wakerlin, g.e. (1934). colloidal mercury sulphide in the treatment of syphilis. archives of dermatology and syphilology, 30, 49-58. weatherill, t. (1833). extraordinary ravages of syphilis and mercury on the human countenance. lancet, 20, 357-359. wilson, r.h., deeds, f. (1939). experimental chronic cadmium poisoning. science, 90, 498. world health organization. (2012). leprosy: fact sheet no. 101. world health organization, geneva, switzerland. http://www.who.int/ mediacentre /factsheets/fs101/en/. viewed 3 june, 2017. youravong, n., chongsuvivatwong, v., teanpaisan, r., geater, a.f., dietz, w., dahlén, g., norén, j.g. (2005). morphology of enamel in primary teeth from children in thailand exposed to environmental lead. science of the total environment, 348, 73-81. zambrano, m., nikitakis, n.g., sanchez-quevedo, m.c., sauk, j.j, sedano, h., rivera, h. (2003). oral and dental manifestations of vitamin ddependent rickets type i: report of a pediatric case. oral surgery, oral medicine, oral pathology, oral radiology, and endodontology, 95, 705-709. zuckerman, m. (2016). more harm than healing? investigating the latrogenic effects of mercury treatment of acquired syphilis in post-medieval london. open archaeology, 2, 42-55. http://www.who.int/mediacentre%20/factsheets/fs101/en/ http://www.who.int/mediacentre%20/factsheets/fs101/en/ broehm et al. 2011.3 55 the mesiodens, the most common type of supernumerary tooth, is found in the midline of the maxilla, between and generally palatal to the central incisors. its prevalence in the permanent dentition ranges from 0.1 to 3.6% and in the primary dentition from 0.2 to 1.9%, (summarized in sykaras, 1975), occurring more commonly in asians (zhu et al., 1996), including presumably native americans, and at least twice as often in males (e.g., liu, 1995; tay et al., 1984). three orientations have been described: vertical (similar to normal teeth); inverted (crown oriented cranially); and horizontal or transverse. vertical or inverted are both common (asaumi et al., 2004; liu, 1995; rajab and hamdan, 2002; tay et al., 1984). the horizontal orientation is rare. asaumi et al. (2004) found only 6% of mesiodens to be horizontal, similar to the rates of 6-8% and 5-6% for all horizontal supernumeraries reported by rajab and hamdan (2002) and tay et al. (1984), respectively. the present report describes the first known incidence of an impacted horizontal conical mesiodens in a child’s skeleton, recovered during on-going investigations at hank’s site (41rb109), an archeological site in the northern texas panhandle. materials and methods the child was interred in a flexed position in a shallow pit filled mostly with caliche cobbles. a radiocarbon assay on human bone collagen from the burial yielded a conventional radiocarbon age of 630 ± 40 years b.p. (beta analytic, inc., sample no. beta-223738). the 2-sigma a horizontal mesiodens in a child buried at hank’s site (41rb109), a prehistoric plains village site in the texas panhandle cory j. broehm*, lisa b. hunter, douglas k. boyd prewitt and associates, inc., cultural resources services, 2105 donley drive, suite 400, austin, texas 78758 calibrated date is a.d. 1,290-1,410. a burned pithouse and other archeological remains at this site are dated to the same time, the plains village period, ca. a.d. 1,200 to 1,500, during which village-based peoples practiced a mixed hunter-gatherer/horticulture subsistence (lintz, 1986). standard osteological analysis was performed on the remains. the skeleton is largely complete and in a good state of preservation. missing elements include most hand and foot bones, unfused epiphyses, the lumbar vertebrae, sternum, and patellae. all deciduous teeth are fully erupted into occlusion and many developing permanent tooth buds are visible partially or wholly in the alveoli due to damage to the maxillae and mandible. based on development of the permanent dentition (ubelaker, 1989) and epiphyseal fusion (scheuer and black, 2000), the child was 3-5 years old at the time he or she died. due to the young age, no assessment of sex was attempted. the child’s skeleton showed no evidence of illness at the time of death. the cranium exhibits positional plagiocephaly. a shallow carious lesion is present on the occlusal surface of the mandibular left first molar. a supernumerary tooth, a mesiodens, is present in the midline of the maxilla, between the deciduous central incisors. *correspondence to: cory j. broehm, po box 16821, albuquerque, new mexico, 87191 usa e-mail: cjbroehm@gmail.com abstract the mesiodens is the most common kind of supernumerary tooth; it is found in the midline of the maxilla. horizontal orientation is the least common, accounting for about 6% of cases. during osteological analysis of the skeleton of a 3 to 5 year old child recovered from hank’s site (41rb109) in the northern texas panhandle, an impacted horizontal, conical mesiodens was identified. the skeleton dates to the plains village period, ca. a.d. 1,200 to 1,500, when village-based peoples practiced a mixed hunter-gatherer/horticulture subsistence. this mesiodens is located in the right maxilla, just lateral to the midline of the hard palate and parallel to the intermaxillary suture. the root projects ventrally and protrudes through the external alveolar bone between the central incisors. the crown is conical. although sometimes found in association with certain congenital disorders, the mesiodens appears to be idiopathic in this case. while possibly painful due to its proximity to the nasopalatine nerve, no sequela from the tooth growth and impaction are evident. dental anthroplogy 2011l;24(2):55-58. 56 case report the mesiodens is located in the right maxilla, just lateral to the intermaxillary suture. it is perpendicular to the orientation of the natural teeth and parallel to the intermaxillary suture. the root points ventrally, protruding through the external alveolar bone at approximately the midpoint level of the central incisor roots, though it is unlikely to have protruded through the gingiva into the vestibule. presence of the mesiodens has resulted in a lateral flaring of the roots of the deciduous central incisors (fig. 1). this suggests the mesiodens developed from the primary dentition, as the mesiodens would have formed prior to formation of the roots of the central incisors. mesiodens of the primary dentition are up to five times less common than those of the permanent dentition (primosch 1981). the crown of the mesiodens points posteriorly and angles slightly superiorly. growth of the mesiodens has led to resorption of bone in the incisive fossa of the hard palate, exposing part of its central crown (fig. 2). this oval fenestration measures 4.28 mm (anteroposterior) by 2.95 mm (mediolateral). the incisive foramen (fossa) is also laterally widened on the affected maxilla. similar resorption along the medial surface of the intermaxillary suture has exposed almost the entire length of the tooth, except the distal half of the crown (fig. 3). a thin bridge of bone separates the palatal and sutural fenestrations. the mesiodens has also caused a slight depression on the intermaxillary suture surface of the left maxilla, anterior to the incisive foramen. there is no evidence of infection or inflammation associated with the mesiodens. the mesiodens measures 11.7 mm in length. its crown is conical in shape (fig. 4) and slightly oval in cross-section at its widest, measuring 6.3 x 5.3 mm. the mesiodens root is incomplete (4.2 mm in length). although there is some postmortem erosion at the root end, the mostly smooth, even margins indicate incomplete development rather than postmortem loss of the rest of the root. it is unclear if development had stopped, leaving an incomplete root, as often happens with a mesiodens (primosch, 1981), or was still ongoing at the time of death. discussion the mesiodens is the most common type of supernumerary tooth, and horizontal mesiodens are the rarest subtype, accounting for about 6% of cases in the literature (asaumi et al., 2004). mesiodens most often occur singly, but may be found in higher numbers. they can be primary or permanent, and normal (eumorphic, like other teeth in the morphogenetic field) or abnormal in crown shape, the latter also having a smaller root and crown (primosch, 1981; russell and folwarczna, 2003; von arx, 1992). the three morphological types of mesiodens with abnormal crowns are conical, tuberculate, and molariform, the first shape being most common (primosch, 1981; rajab and hamdan, 2002). research suggests a multifactorial etiology for supernumerary tooth formation (brook et al., 2002; sedano and gorlin, 1969). a remnant or hyperactive dental lamina or abnormal division of a tooth bud fig. 1. mesiodens root protruding through alveolar bone between the primary central incisors. photograph by jennifer mcwilliams. fig. 2. premortem fenestration of alveolus in the palate dorsal (posterior) to central incisor, exposing the mesioden’s crown. photograph by jennifer mcwilliams. c.j. broehm et al. 57horizontal mesiodens are proposed mechanisms (buggenhout and bailleulforestier, 2008; russell and folwarczna, 2003). certain disorders, particularly cleft lip and palate (milhon and stafne, 1941) and cleidocranial dysplasia (jensen and kreiborg, 1990), are also associated with supernumerary tooth formation. mesiodens erupt less than one-third of the time (liu, 1995; von arx, 1992) but are often asymptomatic. an impacted mesiodens will usually be suspected due to problems in the development of the dentition (e.g. the angulated central incisors in this case) and is then diagnosed radiographically. common clinical sequelae include delayed or lack of eruption of permanent teeth, deviation of eruption path, rotation, retention, root dilaceration, root resorption or loss of tooth, diastema, and malocclusion (e.g., asaumi et al., 2004; nazif et al., 1983; russell and folwarczna, 2003; von arx, 1992; zmener, 2006). eruption of an inverted mesiodens into the nasal cavity can also result in congestion or obstruction of the nasal passage, and development of rhinitis and, possibly, a nasal fistulae (smith et al., 1979). conclusion the horizontal mesiodens recorded in this child from hank’s site in the northern panhandle of texas appears to be idiopathic and not associated with any congenital malformation. while conceivably experiencing pain from the impaction of the tooth, particularly as it impinged on the nasopalatine nerve, the child did not suffer from any obvious problems in development of the primary dentition aside from some flaring of the deciduous central incisors. anterior mesiodens, like the one reported here, tend to create more problems with the primary or permanent dentition than posterior (buggenhout and bailleul-forestier, 2008). but a horizontal mesiodens with a crown distal to the arcade is perhaps less likely to complicate development than a horizontal mesiodens where the crown crowds the arcade, or a vertical or inverted mesiodens (e.g., zmener, 2006). the permanent dentition, particularly the right central incisor, may have eventually exhibited misalignment. literature cited asaumi ji, shibata y, yanagi y, hisatomi m, matsuzaki h, konouchi h, kishi k. 2004. radiographic examination of mesiodens and their associated complications. dentomaxillofac radiol 33:125-127. brook ah, elcock c, al-sharood mh, mckeown hf, khalaf k, smith rn. 2002. further studies of a model for the etiology of anomalies of tooth number and size in humans. connect tissue res 43:289-295. buggenhout gv, bailleul-forestier i. 2008. mesiodens. eur j med genet 51:178-181. jensen bl, kreiborg s. 1990. development of the dentition in cleidocranial dysplasia. j oral pathol med 19:89-93. lintz cr. 1986. architecture and community variability within the antelope creek phase of the texas panhandle. studies in oklahoma’s past, number 14. oklahoma archeological society, norman. liu jf. 1995. characteristics of premaxillary supernumerary teeth: a survey of 112 cases. asdc j dent child 62:262-265. milhon ja, stafne ec. 1941. incidence of supernumerary and congenitally missing lateral incisor teeth in 81 cases of harelip and cleft palate. am j orthod 37:599604. fig. 3. view of mesiodens in intermaxillary suture of right maxilla. ventral (anterior) is to left. photograph by jennifer mcwilliams. fig. 4. mesiodens after removal from maxilla. each square equals 0.1 inch. photograph by jennifer mcwilliams. 58 nazif mm, ruffalo rc, zullo t. 1983. impacted supernumerary teeth: a survey of 50 cases. j am dent assoc 106:201-204. primosch re. 1981. anterior supernumerary teethassessment and surgical intervention in children. ped dent 3:204-215. rajab ld, hamdan mm. 2002. supernumerary teeth: review of the literature and a survey of 152 cases. int j paediatr dent 12:244-254. russell ka, folwarczna ma. 2003. mesiodens-diagnosis and management of a common supernumerary tooth. j can dent assoc 69:363-366. scheuer l, black s. 2000. developmental juvenile osteology. san diego: academic press. sedano ho, gorlin rj. 1969. familial occurrence of mesiodens. oral surg oral med oral path 27:360-362. smith ra, gordon nc, deluchi sf. 1979. intranasal teeth: report of two cases and review of the literature oral surg oral med oral path 47:120-122. sykaras sn. 1975. mesiodens in primary and permanent dentitions: report of a case. oral surg oral med oral path 39:870-874. tay f, pang a, yuen s. 1984. unerupted maxillary anterior supernumerary teeth: report of 204 cases. asdc j dent child 51:289-294. ubelaker dh. 1989. human skeletal remains: excavation, analysis, interpretation, 2nd ed. washington dc: taraxacum press. von arx t. 1992. anterior maxillary supernumerary teeth: a clinical and radiographic study. aust dent j 37:189-195. zhu jf, marcushamer m, king dl, henry rj. 1996. supernumerary and congenitally absent teeth: a literature review. j clin pediatr dent 20:87-95. zmener o. 2006. root resorption associated with an impacted mesiodens: a surgical and endodontic approach to treatment. dent traumatol 22:279-282. daa subscription the secretary-treasurer of the dental anthropology association is dr. loren r. lease of youngstown state university. dr. loren r. lease department of sociology and anthropology youngstown state university one university plaza youngstown, ohio 44555 usa telephone: (330) 941-1686 e-mail: lrlease@ysu.edu dental anthropology now is published electronically and e-mailed to all members as a pdf. if you also want to receive a hard copy, be sure to make this clear on the membership form at the daa website or contact loren. speed communication about your membership by contacting loren directly (other officers may not have current membership information). c.j. broehm et al. shigli et al. 2010.5 28 the protostylid exhibits a range of morphological expression ranging from a pit to a prominent cusp. however, its most common form is a surface irregularity (dahlberg, 1963; mayhall, 1979). human teeth possess an active cingular zone that serves as the point of origin for specific accessory cusps (butler, 1956). in the maxilla, this zone is active primarily on the lingual surfaces of the anterior teeth whereas in the molars, lingual tubercles and carabelli’s trait are expressed. the mandibular teeth are less likely to exhibit development from the lingual cingular zone, while a cingular trait of the lower molars, the protostylid, is sometimes present on the buccal surface of the mesiobuccal cusp. simons (1972) points out that a correlation exists in pongids between well-developed lingual cingula of the upper molars and buccal cingula of the lower molars. this suggests that the carabelli’s traitprotostylid association in the human dentition reflects a long-term developmental relationship in hominoid phylogeny (scott, 1978). the protostylid is also more frequent in early hominid species like those from the genus australopithecus than in later homo species. among australian aborigines, the remarkable characters include those termed the “mongoloid dental complex” (hanihara, 1966, 1967, 1968, 1970) and carabelli’s cusp. the mongoloid dental complex is composed of five crown characters, namely shovel-shape in the maxillary central incisors, cusp six, cusp seven, deflecting wrinkle, and protostylid on the mandibular first molars. this suite of characteristics is similar for deciduous maxillary incisors and mandibular second molars (hanihara 1970). hanihara (1967) stated the protostylid occurs more frequently on the primary than permanent molars. according to dahlberg (1950) and hanihara (1961), whenever the protostylid is present on a permanent molar the trait was present on the primary second molar. however, the reverse situation does not always occur (tongkoom, 1994). hanihara (1961) provides a correspondence to: anand l. shigli, department of pedodontics and preventive dentistry, modern dental college and research centre, gandhi nagar, airport road, indore – 453112, madhya pradesh, india. email address: shigsanand@rediffmail.com a rare form of protostylid: review of literature and case reports anand l. shigli1, sangeeta p. wanjari2, and ruchi ahuja1 1department of pedodontics and preventive dentistry, 2department of oral and maxillofacial pathology, modern dental college and research centre, indore, madhya pradesh, india. abstract human teeth possess an active cingular zone that serves as the point of origin for specific accessory cusps. the term protostylid or protoconid is used for any additional cusps on the buccal surface of maxillary and mandibular premolars and molars. their occurrence in maxillary and mandibular deciduous and permanent dentition is discussed in the literature. this article presents a review of literature in relation to formation of the protostylid, and two cases of prominent protostylids are described, one each in the deciduous and permanent dentitions. dental anthropology 2010;23(1):28-31. classification consisting of seven grades of the protostylid (table). the protostylid also can occur on the primary mandibular second molars (tongkoom, 1994). this cingular feature, which was first reported by bolk (1916), is seen most frequently on the buccal surface of the mesiobuccal cusp of both primary and permanent molars, so an additional cusp on the buccal surface of a molar is referred to as a paramolar tubercle, or bolk’s cusp (tongkoom, 1994). broom (1937) described the protostylid feature on ‘‘a rudimentary external cingulum.” dahlberg (1945) later proposed the term protostylid or parastyle for any anomalous cusp on the buccal surface of maxillary and mandibular premolars and molars (goaz and miller, 1966). dart (1948) described the feature on a molar as ‘‘a laterally-disposed enamel ridge’’ separated from the protoconid by a cingular furrow. dahlberg (1950) also noted that ‘‘although the cusp had its origin as an expression of the cingulum, it is a unit structure, an entity in itself and definitely unlike the continuing cingular eminence seen on the gorilla and other anthropoids.’’ the arizona state university dental anthropology system (asudas), which was devised for the analysis of modern human teeth, defines the protostylid as “a secondary groove that extends mesially from the buccal groove and which culminates in teeth with a marked expression of the protostylid, as a cusp with a free apex” (turner et al., 1991). turner et al. (1991) described it as “a paramolar cusp found on the buccal surface of the protoconid that is normally associated with the buccal groove.” as noted by hlusko (2004), the terms 29 ‘‘protostylid’’ and ‘‘protoconidal cingulum’’ have been used interchangeably when describing features the buccal surface of hominin lower molars. the prevalence of the protostylid varies with race (dahlberg, 1963). it may be present in up to 40% of a population. the protostylid can occur with or without carabelli’s trait on the maxillary molars of arctic people. the carabelli trait frequently appears in caucasoids. like carabelli’s trait, the protostylid has both a similar range of morphological variation and frequency of forms (turner, 1967). hanihara (1968) reported a high frequency of this character in pima indians. suzuki and sakai (1954) found fairly frequent appearance of the protostylid in the mandibular molars of japanese. in mongoloid groups, the protostylid trait occurs in more than 40% of individuals, while in non-mongoloid populations the prevalence is generally below 20%. case reports the following are case reports of two patients who visited the department of pedodontics and preventive dentistry of modern dental college and research centre, indore, madhya pradesh, india. the first case was a 14 year old girl with the chief complaint of decay in right and left lower back teeth. there was no history of pain or any discomfort, and she had no significant health history. examination revealed an unusual accessory cusp in relation to the mesiobuccal cusp of the lower first permanent molars, which also exhibited a four cusp pattern (figs. 1-3). this accessory cusp is grade 6 using hanihara’s (1961) classification (table). the protostylid was strongly developed, giving the appearance of an extra cusp on the buccal surface. there also was a prominent cusp of carabelli on the upper first permanent molars. the lower second premolars showed a y-shape groove pattern. the second case was an 11 year old girl with the chief complaint of a white spot on her upper left front tooth, and she wanted to have her teeth cleaned. she had no significant medical or dental history. examination revealed that the patient had turner ’s hypoplasia on the permanent maxillary left central incisor. an accidental finding was an accessory cusp (fig. 4) on the mesiobuccal cusp of the deciduous maxillary right first molar classified as grade 6 using hanihara’s classification, and a pronounced bulge similar in relation to deciduous maxillary left first molar classified as grade 4 of the same (table). discussion the protostylid forms during the morphogenetic phase of tooth formation, before the onset of dentinogenesis or amelogenesis. the fact that, it is actually the beginning of a cusp formation can be established by the shape of the enamodentin junction (edj) beneath it. these are considered outer enamel surface (oes) traits that are the grade 0: the mesiobuccal groove is straight and there is no trace of any irregularity. grade 1: no evidence of a protostylid, but its presence is suggested by the curvature and branching of the mesiobuccal groove. there may be a small but distinct pit at the lower terminus of the mesiobuccal groove separating the protoconid from the hypoconid. in such a case the buccal groove is slightly bent distalward at the point of the pit. grade 2: the divergence of the mesiobuccal groove is evident grade 3: the two branches of the mesiobuccal groove are more strongly developed than in grade 2. a small triangular area with its tip downward occurs between the branches of the buccal groove grade 4: a shallow groove appears at the mesial corner of the buccal surface. the area between this groove and the mesial branch of the mesiobuccal groove bulges slightly and gives a triangular shape with its tip upward. grade 5: the triangular area is more strongly developed than in grade 4. grade 6: the protostylid is strongly developed so that the tooth seems to have an extra cusp on the buccal surface of mesiobuccal cusp. table 1. hanihara’s (1961) classification is composed of seven grades of protostylid forms rare protostylid form 30 fig. 1. protostylid in relation to mesiobuccal cusp of permanent mandibular right first molar. fig. 2. protostylid in relation to mesiobuccal cusp of permanent mandibular left first molar. fig. 3. bilaterally appearing protostylid on the mandibular permanent first molars. fig. 4. bilaterally appearing well-pronounced protostylid on deciduous maxillary left and right first molar. result of enamel being laid down over a template in the membrana preformativa during the formation of the tooth crown (butler, 1956). in mature teeth the shape of this membrane persists as the edj. although this informative morphology is preserved at the edj may not always be present at the oes due to a lack of correspondence between the two surfaces (due to differential enamel deposition) or due to dental attrition (skinner et al., 2009). the location and the morphology of protostylid pits make them similar to occlusal fissures. both features open at the bottom of the groove between the two cusps, and they both extend to the most concave point of the enamodentin junction. the depth of the normal fissure depends on the distance between two growth centers (awazawa et al., 1989), which is on a concavity of the edj, and the same probably is true for protostylid pits. soon after the beginning of amelogenesis at this site, the enamel organ becomes increasingly constricted because of the concave edj. eventually, amelogenesis at the foot of the pit ceases and the ameloblasts lose their tomes’ processes and form a layer of surface aprismatic enamel (gaspersic, 1993). a.l. shigli et al. 31rare protostylid form the protostylid has been viewed both as an accessory cusp and as a remnant of a cingulum (i.e., a crestal feature). this distinction is relevant to considerations of whether the feature is a cusp or a crest, but this depends on the definition of a cusp. the primary cusps of all primate teeth have a dentin horn, which forms early in the development of the tooth crown on the surface of the inner enamel epithelium, and is subsequently covered by enamel. this is also the case for the majority of accessory cusps, such as cusp six and cusp seven (skinner et al., 2008), and even small features such as marginal ridge tubercles on upper molars and the mammelons present on unworn incisors (kraus and jordan, 1965). only in rare circumstances in extant hominoids and fossil hominins are there ‘‘enamel-only’’ cuspules (i.e., small cusps with no underlying dentin horn). thus, for the purpose of defining the protostylid trait a structure defined as a cusp should exhibit an underlying dentin horn at the edj surface. the protostylid pit may lie between a large protoconid and a nearly negligible protostylid consisting only of dentin core (gaspersic, 1993). conclusion the protostylid and carabelli’s trait was found to co-occur in the two cases described. this combination is interesting because these traits occur on homologous cusps in opposite jaws (tongkoom, 1994). the similarity in form and position of this structure in contemporary man and in prehistoric forms is considered as evidence of a relationship between these groups. literature cited awazawa y, hayashi k, awazawa i, tobari h. 1989. pathomorphological study of the supplemental groove. bull group int rech sci stomatol odontol 32:145-156. bolk l. 1916. problems of human dentition. am j anat 19:91-148. broom r. 1937. discovery of a lower molar of australopithecus. nature 140:681-682. butler pm. 1956. the ontogeny of molar pattern. biol rev 31:30-70. dahlberg aa. 1945. the changing dentition of man. j am dent assoc 32:676-690. dahlberg aa. 1950. the evolutionary significance of the protostylid. am j phys anthropol 8:15–25. dahlberg aa. 1963. analysis of the american indian dentition. in: brothwell dr, editor. dental anthropology. oxford: pergamon, p 149-177. dart ra 1948. the adolescent mandible of australopithecus prometheus. am j phys anthropol 6:391-411. gaspersic d. 1993. morphology of the most common form of protostylid on human lower molars. j anat 182:429-431. goaz pw, miller mc. 1966. a preliminary description of the dental morphology of the peruvian indian. j dent res 45:106-119. hanihara k. 1961. criteria for classification of crown characters of human deciduous dentition. j anthropol soc nippon 69:27-45. hanihara k. 1966. mongoloid dental complex in deciduous dentiton. j anthropol soc nippon 74:9-20. hanihara k. 1967. racial characteristics in the dentition. j dent res 46:923-926. hanihara k. 1968. morphological pattern of deciduous dentition—the japanese american hybrids. j anthropol soc nippon 76:114-121. hanihara k. 1970. mongoloid dental complex in the deciduous dentition, with special reference to the dentition of the ainu. j anthrop soc nippon 78:3-17. hlusko lj. 2004. protostylid variation in australopithecus. j hum evol 46:579-594. kraus bs, jordan re. 1965. the human dentition before birth. philadelphia: lea and febiger. mayhall jt. 1979. the dental morphology of the inuit of the canadian central arctic. ossa 6:199-218. scott gr. 1978. the relationship between carabelli’s trait and the protostylid. j dent res 574:570-575. simons el. 1972. an introduction to man’s place in nature: primate evolution. new york: macmillan, p 242. skinner m., wood ba, hublin jj. 2009. protostylid expression at the enamel-dentine junction and enamel surface of mandibular molars of paranthropus robustus and australopithecus africanus. j hum evol 56:76-85. skinner mm, wood ba, boesch c, olejniczak aj, rosas a, smith ts, hublin jj. 2008. dental trait expression at the enamel-dentine junction of lower molars in extant and fossil hominoids. j hum evol 54:173-186. suzuki m, sakai t. 1954. on the “protostylid” of the japanese. zinruigaku zassi 63:81-84. tongkoom s. 1994. the prevalence of dental anomalies in chinese children. thesis, masters in dental surgery, department of children’s dentistry and orthodontics. hong kong. retrieved on september 16, 2009. http:// sunzi.lib.hku.hk/hkuto/view/b31953980/ft.pdf turner cg ii. 1967. dental genetics and microevolution in prehistoric and living koniag eskimo. j dent res 46:911-917. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley m, larsen cs. editors. advances in dental anthropology. new york: wiley-liss, p. 13-31. scott 2013.1 3 in memoriam: christy g. turner ii (november 28, 1933 – july 27, 2013) personal reflections on his legacy in dental anthropology and beyond i was an undergraduate at arizona state university in 1966 when christy was brought into the department of anthropology. i took three of his courses as an undergraduate: world prehistory, southwest archaeology: anasazi, and physical anthropology (human biology). i mention this because his courses were both a challenge and an inspiration. he was the most charismatic professor i had encountered and when he discovered i was a fairly good student, he slowly brought me into the 'physical anthropology' fold, redirecting me away for my original goal of becoming a professional archaeologist. he talked charles woolf into offering me a graduate fellowship in genetics and that dictated my direction in graduate school, the genetic analysis of dental morphological traits. in retrospect, i got in on the ground floor of something that would eventually become a very significant edifice in the field of physical anthropology and it was christy who laid much of the foundation. christy was all that one could ask for in a mentor. he was encouraging yet demanding. when i was thinking about taking a few extra courses as a graduate student, he said something i tell my students to this day: "when you finish your phd, you don't stop learning.........that's when you start learning." that was more prophetic than i knew at the time. that stimulated me to finish my phd in expeditious fashion without taking a lot of extra coursework. when i defended my dissertation in the summer of 1973, i was christy's first phd in physical anthropology. through his wisconsin contacts, he helped me secure a job at the university of alaska fairbanks. although alaska was definitely not my first choice to start my career, the doors of academia were closing at that time so i took the job and eventually appreciated the opportunities it provided. as his dissertation was titled the dentition of arctic peoples he could not have been happier about where i landed, despite my initial reluctance to go from the fire (arizona) to the icebox (alaska). after leaving for alaska, christy and i always stayed in close touch and collaborated on many articles. neither of us ever thought much about writing books, but in the 1990s, at gabe lasker's invitation, we wrote a book published by cambridge university press entitled the anthropology of modern human teeth: dental morphology and its variation in recent human populations (1997). when the book drew near completion, we were talking about titles. i originally suggested only the second half of the title above. it was christy who thought 'the anthropology of modern human teeth' had more panache, and was often the case, he was absolutely right. while christy was not the 'father' of dental anthropology, an honor that should go to albert a. dahlberg and p.o. pedersen, he was definitely the major driving force in the field for the past 40+ years. in 2010, joel irish (phd, asu, 1993) and i organized a symposium in christy's honor at the aapa meeting in albuquerque, new mexico. we had no trouble finding contributors to a full symposium and even had to pull our own papers to keep the number to the maximum allowed of 14. after the symposium, we submitted a book proposal to cambridge for a festschrift volume entitled anthropological perspectives on tooth morphology: genetics, evolution, variation. of the 21 papers in the final volume, six authors were former students of his. thankfully, the volume appeared in march, 2013, so christy had time to appreciate how others in dental anthropology viewed his monumental contributions. the second chapter, written by christy, provides an excellent summary of his academic and professional life, along with acknowledging the many students he mentored during his decades of service at asu. the traits that best describe christy are charismatic, driven, productive, imaginative, and far sighted. while others described dental morphological traits, christy could see their potential in asking questions of population origins and relationships. he travelled the world over and made dental observations on over 30,000 human skeletons. he knew the insides of about every museum in north america and many in south america, siberia, north asia, southeast asia, and europe. but he didn't just de4 scribe teeth; he developed the methods that are the foundations of modern dental comparative studies (the arizona state university dental anthropology system). beyond methods, he developed models that addressed long-standing historical issues, including his three-wave model for the peopling of the americas, and the dental division between north asians (sinodonts) and southeast asians (sundadonts). while his ideas may or may not prove to be correct in the long run, he developed models that other researchers had to consider, even if they disagreed with him. on another front, christy started what was basically a new field of inquiry when he examined what was presumed to be a secondary burial from polacca wash, a site near the abandoned hopi village of awatovi. although his interest, per usual, was in making dental observations, he thought this collection of broken and burned bones could hardly be a secondary burial. after a detailed analysis of cut marks, anvil abrasions, burned bone, etc., he wrote his first paper on southwest cannibalism entitled "a massacre at hopi," co-authored with one of his graduate students, nancy tucker morris. after examining this series, he ran down many more skeletal collections from the anasazi region that could most parsimoniously be explained by cannibalism. needless to say, this was not a popular view and he was attacked by native americans and professional colleagues who took issue with his interpretation. the culmination of this work came in the volume man corn: cannibalism and violence in the prehistoric american southwest (1999), co-authored with jacqueline, his wife, companion, and collaborator. always thorough to an admirable fault, he went to central mexico and examined skeletal series where cannibalism was widely acknowledged. his view was that if you disagreed with his taphonomic signature for cannibalism, provide an alternative explanation for bones that had been bashed, burned, and butchered. christy had file after file of papers written on the subject and he never felt anyone seriously dented his interpretation of cannibalism, which he always clearly separated from evidence of just violence. christy was definitely the hardest working scholar i have ever known. even with failing health and eyesight greatly diminished by macular degeneration, he just completed another book for cambridge university press entitled animal teeth and human tools: a taphonomic odyssey in ice age siberia. how he could write and edit a 500 page volume with dozens of tables and photos with all of his physical limitations astounds me to this day. he had a great career and had already made significant marks in dental anthropology and the taphonomy of human cannibalism but he kept pressing on. thankfully, he finished all the edits and copy proofing of the galleys this past spring and the volume is now in press. sadly, he will not be around to see this work in book form. when i was a graduate student, christy told me his academic idols were william healy dall, franz boas, and aleš hrdlička, who published, respectively 1500, 800, and 600 papers and books. i know christy's vita is over 50 pages long but i'm not sure if he matched those gentlemen.........of this i am sure though, he gave it 'the old college try.' for over 40 years, christy and i (and our families) remained close; we stayed with the turners on campo alegre many times and they stayed with us when they came to alaska. i could go on and on about the many things we did, crazy and otherwise, but i will save those for private conversations, preferably at a bar during annual meetings of the american association of physical anthropologists. his legacy is substantial, his footprint is large……..he will be missed and remembered by his daughters and grandchildren along with countless former students and colleagues because he was a ‘unique character,’ one whose time on earth made the world a more interesting place. g. richard scott department of anthropology university of nevada reno reno nv 89557 28 dental anthropology 2023 │ volume 36│ issue 01 this is a morphological and metric description of a deciduous maxillary central incisor excavated from the archaeological site trail creek cave 2 on the seward peninsula in western alaska by helge larsen in 1949 and 1950 (larsen, 1968). the tooth stored at the national museum in copenhagen was the only human skeletal remain among thousands of animal bones retrieved from excavation (pasda, 2012). pasda (2012) identified the tooth as a left i1 (upper left permanent central incisor), instead of a left i1 (upper left deciduous central incisor) and described it as a slightly worn tooth with the root not fully formed. the tooth derives from cave 2, section 4m, layer iii. the deciduous tooth is radiocarbon dated to 8085 ±40 bp, hence from early holocene (moreno-mayar et al., 2018). the morphological examination was requested by the centre for geogenetics in copenhagen, denmark prior to the destructive genetic analysis. images of the tooth were provided before the root was cut for radiocarbon dating (figure 1a and 1b). additionally, a 3d surface scan was provided of the crown which could be digitally rotated and from where images could be extracted with different views of the tooth. within dental anthropology, tooth morphology can be related to regional populations (hanihara, 1967; scott and turner, 1997). this applies to the deciduous as well as the permanent dentition. most researchers today favour the hypothesis that upper palaeolithic populations of hunter-gatherer reached northeast asia 30,000+ years before the last glacial maximum (lgm) (pitulko et al., 2004). during the lgm the landmass between asia and north america called beringia became a refugium morphological and metric description of a rare mesolithic deciduous tooth from trail creek caves, alaska verner alexandersen 1 , lasse vinner 2 , charlotte primeau 1,3* 1 laboratory of biological anthropology, department of forensic medicine, university of copenhagen, frederik v's vej 11, 2100 copenhagen, denmark 2 lundbeck geogenetics centre, globe institute, university of copenhagen, østervoldgade 5-7, 1350 copenhagen, denmark 3 warwick manufacturing group (wmg), university of warwick, england, uk abstract a human deciduous maxillary central incisor from trail creek caves, seward peninsula, alaska, is described. the tooth from ancient beringia is radiocarbon dating to 8085 ±40 bp. the tooth is compared to the incisors from the deciduous dentition of usr1 from the upward sun river site in central alaska dating to ca. 11,500 (cal) bp. genetic analysis of the trail creek child and the usr1 child showed that they both belonged to an ancient eastern beringian population that remained isolated in present-day alaska during the late pleistocene and early holocene. the tooth was measured using a sliding calliper and the morphology of the tooth described directly from macroscopic evaluation as well as from a 3d surface scan. based on tooth development, the age of the trail creek child corresponds to an age of 1-1.5 years. the sex of the child is determined as female from the genetic analysis. the tooth was expected to show the characteristic shovel-shape of native americans but was without marked shovel-shape. the variability of shovel-shape in maxillary deciduous and permanent incisors is discussed and it is suggested that the trait shovel-shape in a deciduous dentition is more reliably recorded on the maxillary lateral incisors than the central incisors. *correspondence to: charlotte primeau wmg university of warwick coventry, england, uk e-mail: charlie.primeau@warwick.ac.uk keywords: tooth morphology, basal cingulum, maxillary, shovel-shape, ancient 29 dental anthropology 2023 │ volume 36│ issue 01 for northeast asian groups of hunters (ca. 20.000 – 15 thousand years ago). at the end of the lgm the hunters migrated along the coast and along land corridors into north america (scott et al., 2016). these prehistoric native americans had their dentitions described by turner (1983). he observed three fairly clear geographic clusters: ‘alaska interiornorthwest coast mainly na-dene-speaking indians; arctic coast (aleut-eskimo) and all the rest of north and south america (indian)’. all three clusters had a sinodont dental pattern in their permanent dentitions. the anterior teeth in such a dental pattern have a high frequency of shovel-shape. it is the purpose of this examination to study the morphology of the trail creek incisor and compare with anterior teeth from another and more ancient alaskan child (usr1, dated ca. 11,500 cal. years bp) (potter et al., 2014). the hypothesis was that the trail creek tooth would show a sinodont morphology, like usr 1 and other native americans. the genomes of the children from the trail creek and usr1 sites have been analysed by geneticists and the results are included in recent literature on the first americans (moreno-mayar et al., 2018; hoffecker et al., 2020, 2021). genetic analysis the genetic analysis revealed the trail creek individual as female. sequencing of ancient dna recovered from the trail creek specimen was expanded to ~0.4× genomic depth of coverage, using illumina high-throughput sequencing. the results of the genomic analyses were previously described in detail (morenomayar et al., 2018). in brief, initial multidimensional scaling analysis indicated genomic affinity between trail creek and another contemporaneous specimen (usr1) from the same region and showed similar proportions of siberian and native american genomic components. the mtdna haplotype belonged to b2 (shared with usr2 -a low-coverage genome of a close relative to usr1), although different from the derived b2 variant found throughout other parts of the american continents (moreno-mayar et al., 2018). furthermore, f3-statistical analysis suggested that trail creek (like usr1) are similarly related to other native americans. finally, d-statistics and admixture graph-fitting, using qpgraph, supported a model in which the trail creek genome form a clade with usr1 to the exclusion of other known northand southnative americans. the collective genetic evidence from trail creek and usr1, which also showed similar archaeological artefacts, support that the trail creek tooth came from an individual that belonged to an ancient metapopulation present in eastern beringia. this population who remained isolated in presentday alaska during the late pleistocene and early holocene were equally related to north and southnative american populations (moreno-mayar et al., 2018). age assessment of the child the incisal edge of the crown was slightly figure 1. images provided prior to this examination. 1a is the lingual surface seen from the mesial side. 1b is the facial surface seen from the distal side. scale bars represent millimetres. 30 dental anthropology 2023 │ volume 36│ issue 01 worn, and the root formation not completed. from inspection of the provided photos (see figure 1a and 1b) the root length was estimated to be 2/3 to 3/4 completed. the apical opening was wide and the root walls very thin (stage f according to liversidge and molleson, 2004). the development of the tooth corresponds to an age of 1-1.5 years (alqahtani et al., 2010, figure 6, liversidge and molleson, 2004, table 2). overall description of the trail creek tooth the facial surface of the crown was flat without double-shovel and almost square with a mesiodistal breadth of 6.7 mm and a crown height of 6.6 mm (figure 2a). the apical part of the root was bent in a facial direction as expected from deciduous maxillary incisors (see figure 1b). the lingual surface of the crown had weakly developed marginal ridges on each side of a very shallow central fossa (figure 2b). this corresponds to trace of shoveling in the terminology of hanihara (1967) or sciulli (1998). of the two marginal ridges, the distal ridge is more distinct. the basal cingulum occupied the gingival half of the lingual surface. from this bulging eminence, there was an extension in the direction of the incisal edge (figure 3a and 3b). this was observed on the scan, while it was indistinct from visual figure 2. the tooth at the time of examination. figure 2a is the facial surface with the mesial edge to the left. figure 2b is the lingual surface with the distal edge to the left. scale bar represents millimetres. figure 3. scanning images of the deciduous central incisor crown showing the attritional facet (arrows). 3a is seen from the mesial side. 3b is seen from the lingual surface. 3d scanning was after the root was removed for radiocarbon dating, so tooth crown was mounted on a stance. 31 dental anthropology 2023 │ volume 36│ issue 01 inspection or from the photograph (see figure 2b). in table 1, the results are presented with use of the terminology described by (sciulli, 1998). the 3-dimensional digital model created by surface scanning using a trio scanner (3shape, copenhagen) deserves further comment. the scanning images illustrated a small attritional facet visible on the mesial surface of the crown, caused by friction between the two central incisors (see figure 3a and 3b). hence the tooth had been erupted and in use for some time. the scanning images showed no visible microwear. the mesial attritional facet visible on the scanning images was not apparent on the tooth when viewed directly. this imaging method was therefore a valuable addition to the macroscopic examination of the tooth. the facet was formed during a very short functional period from the eruption of the central incisors at circa 10 months of age to the death of the child at about 18 months of age (see above). it is important to note that enamel of deciduous teeth is not fully mineralized at the time of eruption (nanci, 2013; harris and lease, 2005). a larger brown discoloured spot was observed on the facial surface of the crown (see figure 2a) and a minor spot on the lingual surface (see figure 2b). these extrinsic discolorations are most likely due to absorption of pigment particles from the soil. the post-mortem cracks in the enamel are likewise stained by unknown material (see figure 2a). comparative material from alaska for comparison with the trail creek tooth, it is relevant to mention the complete deciduous dentition of the young child from an upward sun river site (usr1) in central alaska, reported in the paper by potter et al. (2014). the nonmetric crown traits of the teeth belonging to usr1 were compared to a pooled prehistoric sample of ohio native americans studied by sciulli (1998) (see table 1). the maxillary central incisors of usr1 showed only a trace of shoveling. the upper lateral incisors and the lower lateral incisors showed a higher grade of the trait shovelshape than the upper central incisor and it was concluded that usr1 was a native american child with a sinodontlike deciduous dentition. discussion of shovel-shape in the deciduous dentition shovel-shape in the deciduous dentition was first classified by hanihara (1963) and later followed up by sciulli (1998) with the following definitions: 0: no shovel-shape, lingual surface smooth, 1: semi shovel-shape, slight elevation of marginal ridges, 2: shovel, marginal ridges easily seen, and 3: strong or marked shovel when marginal ridges are broad and high. a shovel-shaped incisor means grade 2 or 3 to most researchers. in europeans and western eurasians, the maxillary incisors are usually without shovel-shape in comparative sample individual usr1* trail creek trait n breakpoints** %** status grade status grade shovel 163 2-3/0-3 77.3 absent 1 absent 1 double shovel 157 1-3/0-3 20.4 absent 0 absent 0 interruption groove 161 1-4/0-4 0.0 absent 0 absent 0 tuberculum dentale 155 1-4/0-4 11.6 present? 1? absent 0 table 1. nonmetric crown traits for deciduous upper central incisors *values for usr1 are from potter et al., 2014. ** comparative sample of 370 individuals from 26 prehistoric ohio valley populations (ca. 3000-350 bp), sciulli, 1998. 32 dental anthropology 2023 │ volume 36│ issue 01 grade 2 and 3 while it is common in east asian populations and native americans and inuit (table 2). shovel-shape of maxillary incisors is often more distinct on the lateral than the central incisors in the same dentition (sciulli, 1998). lukacs and kuswandari (2013) therefore recorded shovel-shape on maxillary lateral incisors in their study of malayan children. in the permanent dentition shovel-shape is more common than in the deciduous dentition (table 3). it does not follow from the lack of marked shovel-shape in the trail creek central incisor that shovel-shape also was missing on the upper lateral incisors. the strength of correlation between deciduous and permanent incisors in the same individual has been studied by saunders and mayhall (1982). they studied individuals of european ancestry with a low frequency of marked shovel-shape. they found that absence or trace shoveling in the deciduous dentition also meant absence in the permanent successor but occasionally was absent followed by some degree of shovel in the permanent dentition (table 4). edgar and lease (2007) likewise studied european americans as children and adults. hanihara´s and sciulli´s descriptions were used for their recordings of deciduous teeth while the asu dental anthropology system was used for the permanent teeth (scott and irish, 2017). edgar and lease (2007) expected high correlation between the two dentitions, but their null hypopulation n grade 0 and 1 (%) grade 2 and 3 (%) reference eskimo 16 50.0 50.0 hanihara, 1966 pima indian 78 38.4 61.5 hanihara, 1966 pima indian 53 49.1 50.9 tocheri, 2002 amerindian, ohio 163 22.7 77.3 sciulli, 1998 japanese (wajin) 124 23.4 76.6 hanihara, 1963 prehistoric jomon 24 62.5 37.5 kitagawa et al., 1995 ainu 4 50.0 50.0 kitagawa et al., 1995 malay 129 93.0 7.0 lukacs and kuswandari, 2013 australian ab. 38 23.7 76.3 hanihara, 1963, 1965 amer. w/danish 19 84.2 15.8 present authors (unpublished) american white 20 100.0 0.0 hanihara, 1966 jats 68 95.6 4.4 kaul and prakash, 1981 inamgoan, chalchol. 39 84.6 15.4 lukacs and walimbe, 1984 table 2. population frequencies for shovel-shape of deciduous maxillary central incisors permanent i1 absent permanent i1 trace permanent i1 semi-shovel permanent i1 shovel-shaped deciduous i1 absent 76.6% 16.9% 1.5% 0.5% deciduous i1 trace 2.5% 2.5% 1.5% 0.0% table 3. frequencies of the various expressions of shovel-shape in deciduous and permanent incisors grade 0 and 1: includes no shovel-shape and semi-shovel 1; grade 2 and 3: marked shovel-shape. grade 3 is rarely observed according to hanihara (1963), who only found it in few american indians. lukacs and kuswandari (2013) and kitagawa et al. (1995), likewise observed no children with shovel grade 3, only with grade 2. the authors acknowledge that some of the terminology within this paper is no longer acceptable, but references as the originally presented to avoid confusion within the literature. from saunders and mayhall (1982), table 1, p.46, based on 650 children from burlington, canada. ninety percent of all parents of these children had their ancestry traced to the british isles or continental europe; the remainder was also of caucasoid origin. the figures add up to 100% di1. 33 dental anthropology 2023 │ volume 36│ issue 01 pothesis was nevertheless that there is not a strong significant correlation between trait expression in the deciduous and permanent teeth. their results showed that correlations for maxillary incisors were non-significant supporting saunders and mayhalls (1982) results and the null hypothesis was likewise supported for all other types of incisors with one exception. surprisingly the correlation for mandibular second incisor shoveling was significant, negating the null hypothesis. there is, however, a need for similar studies in populations with high frequency of shovel-shape where a higher inter-dentition correlation for shovel-shape possibly can be observed. tooth size the mesiodistal and buccolingual crown diameters of the trail creek incisor were measured and compared to results from studies of archaeological skeletal material and plaster casts from modern living children. the tooth was measured with a mitotoyo sliding calliper to an accuracy of 0.1 mm. mesiodistal measurements can be made with the same precision near the incisal edges on actual teeth and casts. however, measurements of the buccolingual diameters require the basal cingulum to be fully exposed. this is the case for teeth in skeletal material or isolated teeth. in casts with teeth in situ, made from living individuals, the basal cingulum of the central deciduous incisor can be partly covered by gingiva. a minor unknown error in buccolingual crown sizes measured on plaster casts compared to skeletal material is thereby a possibility. in table 5, the size of very few central decid mesiodistal diameter buccolingual diameter population n (x̄) sd n (x̄) sd reference mesolithic trail creek 1 6.7 n/a 1 5.6 n/a present study mehrgahr 3 (preceramic, <8000 bp) 8 7.1 0.43 9 5.58 0.2 lukacs and hemphill, 1991 vedbæk (denmark, 7500-7300 bp) 1 7.1 n/a 1 5.3 n/a alexandersen, 1976 western europe (arene candide, ofnet, muge, hohlenstein, 8-5000 bp) 7 7.2 0.46 7 5.3 0.34 frayer, 1978 neolithic mehrgahr 2 (chalcolithic, 6500 bp) 4 6.83 0.39 4 5.38 0.46 lukacs and hemphill, 1991 tell leilan, syria (4300-4200 bp, bronze age) 2 6.75 n/a 2 5.25 n/a haddow and lovell, 2003 ohio indians (ca. 3000 bp) 24 6.5 0.41 24 4.8 0.33 sciulli, 1990 table 5. tooth size of the deciduous maxillary central incisor in archaeological material population permanent (i1and i2) % (n) deciduous (di1) % (n) eskimo 100.0 (21) 50.0 (16) pima indian 99.1 (222) 61.6 (78) japanese ainu 81.4 (97) 50.0 (4) american whites 27.7 (83) 0.0 (20) table 4. frequency distributions of shovel-shape in deciduous and permanent dentitions from hanihara et al. (1975), tables 3.5-1 and 2, page 258. shovel-shape grade 2+3. 34 dental anthropology 2023 │ volume 36│ issue 01 uous incisors known from mesolithic and neolithic archaeological sites in europe, syria and pakistan are presented. the mesolithic period is here considered to begin after the ice age at about 11,500 bp, thus including the tooth from trail creek. the mesiodistal diameter of the tooth from trail creek is close to 1 standard deviation (sd) below the mean value for the two small mesolithic samples while it is comparable to the few neolithic near east incisors. the buccolingual diameter of the trail creek tooth is within 1 sd of the mean values for the comparative mesolithic samples. the diachronic change in tooth size is very small, if existing at all, in the deciduous dentition as seen from table 5. the archaic native americans from the ohio valley had smaller central deciduous incisors than the trail creek tooth, but the recent pima indians from southern arizona and the asiatic japanese and taiwanese children had matching mesiodistal diameters although smaller buccolingual diameters. recent europeans have mesiodistal diameters comparable to the alaskan tooth, but again smaller buccolingual diameters. table 6 show sizes of modern populations where sex is known, hence data are sex specific. in modern populations the smallest deciduous incisors occur in europeans. the trail creek incisor fits among the modern asiatic and new world samples represented in table 5. conclusions this metric and morphological examination has documented a rare deciduous left central incisor from trail creek cave 2, alaska, dated to 8085+/-40 bp. the age of the child corresponds to an age of 1-1.5 years based on incomplete development of the root. the lingual surface of the crown showed only a trace of shovel-shape and a prominent basal cingulum. comparison with the central incisor from the usr1 child (potter et al., 2014) showed that this incisor (usr1) also had minimum trace of shovel-shape. several anterior teeth were available from the usr1 child and the lateral maxillary and mandibular incisors in this dentition showed a higher grade of shovel -shape and was characterized as a sinodont dentition belonging to a native american child. review of the literature has shown that shovel-shape occurs with a lower frequency in deciduous than in permanent maxillary incipopulation mesiodistal diameter buccolingual diameter reference n (x̄) sd n (x̄) sd pima native indians, boys 22 6.83 0.49 23 5.20 0.35 alvrus, 2000 pima native indians, girls 22 6.81 0.28 22 5.06 0.49 japanese, boys 42 6.87 0.46 n/a n/a n/a mizoguchi, 1998 taiwanese, boys 60 6.77 0.38 60 4.89 0.22 tsai, 2000 taiwanese, girls 57 6.62 0.42 57 4.78 0.36 american white, boys 90 6.46 0.39 n/a n/a n/a meredith and knott, 1970 american white, girls 90 6.32 0.42 n/a n/a n/a american white, boys 25 6.50 0.29 23 5.20 0.25 alexandersen, 1969 american white, girls 18 6.31 0.50 17 4.95 0.41 jordanians, boys 34 6.54 0.39 43 4.95 0.33 hattab et al., 1999 jordanians, girls 40 6.46 0.32 31 4.87 0.27 icelanders, boys 20 6.49 0.45 29 5.08 0.26 axelsson and kirveskari, 1984 icelanders, girls 18 6.43 0.45 20 5.01 0.30 australians, boys 28 7.34 0.47 n/a n/a n/a brown et al., 1980 australians, girls 10 7.15 0.46 n/a n/a n/a table 6. tooth size of the deciduous maxillary central incisor in modern samples 35 dental anthropology 2023 │ volume 36│ issue 01 sors of the given population. the trait shovelshape occurs with a higher frequency on lateral than central incisors in the deciduous dentitions. it is also pointed out that the degree of shovel-shape is not necessarily the same in both dentitions of a given individual. lack of strong correlation has been established for european americans but there is need for a similar study in individuals of native american origin. the mesiodistal crown diameter of the trail creek tooth was of modern size. the buccolingual diameter was large as expected considering the prominent basal cingulum. acknowledgements the authors would like to thank peter dahl from 3shape, copenhagen, for generously making available the trio dental scanning equipment and software. the analysis of the tooth, including the destructive analysis, was approved by the tribal president from deering ira council on behalf of the native village of deeing (morenomayar et al., 2018: si page 40). the authors would also like to thank the reviewers for their useful and helpful comments on the manuscript. references alexandersen, v. 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(2004). variation in crown and root formation and eruption of human deciduous teeth. american journal of physical anthropology 123, 172-180. lukacs, j. r. & hemphill, b. e. (1991). the dental anthropology of prehistoric baluchistan: a morphometric approach to the peopling of south asia (pp. 77-121). in m. a. kelley & c. s. larsen (eds.). advances in dental anthropology. new york: wiley-liss. lukacs, j. r. & walimbe, s. r. (1984). deciduous dental morphology and biological affinities of a late chalcholithic skeletal series from western india. american journal of physical anthropology 65, 23-30. lukacs, j. r. & kuswandari, s. (2013). crown morphology of malay deciduous teeth: trait frequencies and biological affinities. in: scott, g. r. & irish, j. d. (eds.). anthropological perspectives on tooth morphology, genetics, evolution, variation (pp. 453479). cambridge university press. meredith h. v. & knott, v. b. 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(2018). early human dispersals within the americas. science,10.1126/science.aav2621. nanci, a. (2013). ten cate’s oral histology, 8th edition. st. louis: elsevier mosby. pasda, k. (2012). seward peninsula, alaska: trail creek caves 2 and 9 revisited. the skeletal remains. bar international series 2374, 179. pitulko, v.v., nikolsky, p.a., girya,e.yu, basilyan, v.e., tumskoy, v.e., koulakov, s.a., astakhov, s.n., pavlova, e. yu, anisimov, m.a. 2004 the yana rhs site: humans in the arctic before the last glacial maximum. science 303, 52-56. potter, b. a., irish, j. d., reuther, j. d. & mckinney, h. j. (2014). new insights into eastern beringian mortuary behaviour: a terminal pleistocene double in37 dental anthropology 2023 │ volume 36│ issue 01 fant burial at upward sun river. proceedings of the national academy of sciences pf the united states of america (pnas), 111(48), 17060-17065. saunders, s.r. and j.t. mayhall. 1982. fluctuating asymmetry of dental morphological traits: new interpretations. human biology 54, 789-799. sciulli, p. w. (1990). deciduous dentition of a late archaic population of ohio. human biology 62, 221-245. sciulli p. w. (1998). evolution of the dentition in prehistoric ohio valley native americans: ii morphology of the deciduous dentition. american journal of physical anthropology 106, 189-205. scott, g. r. & irish, j. d. (2017). human tooth crown and root morphology. the arizona state university dental anthropology system. cambridge university press, cambridge. scott g. r. & turner ii, c.g. 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(2001) morphological characteristics of the deciduous teeth. the journal of clinical pediatric dentistry 25(2), 95-101. 3 dental anthropology 2018 │ volume 31 │ issue 01 frequency of occurrence and degree of expression of the parastyle in several modern human populations graham scriven 1 , james rogers 1 , alan brook 1,2 , g. richard scott 3 , suzanna mihailidis 1 , mohd fadhli bin khamis 4 , grant townsend 1,* 1 adelaide dental school, the university of adelaide, south australia 5005 2 institute of dentistry, queen mary university of london, uk 3 university of nevada, reno, usa 4 school of dental sciences, universiti sains malaysia, kota bharu, malaysia keywords: dental morphology, humans, paramolar cusps, genetics, supernumerary teeth since louis bolk (1916) first described an unusual projection on the buccal surfaces of maxillary molar crowns, researchers have had trouble explaining its etiology and giving the feature an appropriate name. the trait has been termed a maxillary paramolar cusp, paramolar tubercle, stylar anomalous cusp, supernumerary inclusion, and a parastyle. there are few more enigmatic features in the human dentition. albert dahlberg was aware that some system of identification needed to be established to standardise methodology and he devised his own descriptive method (dahlberg, 1945). the importance of dahlberg’s terminology was that he considered the feature in terms of its location on the mesiobuccal cusp of the permanent maxillary second and third molars (that is, on the paracone or cusp 2) and, by applying his paleontological knowledge, he referred to it as a parastyle (dahlberg, 1945). a similar feature was noted in a corresponding position on the protoconid of the lower molars and dahlberg called it a protostylid. another difficulty encountered by researchers when studying parastyles has been how to describe their size objectively. these traits are difficult to assess with only limited guidelines (e.g., a single standardised plaster reference plaque) for comparison. many previous references to parastyles have been case reports or linked to descriptions of the management of supernumerary teeth that have included photographs and radiographs as illustrations (nagaveni et al., 2010; parolia et al., 2011; duddu et al., 2012; nabeel et al., 2012; jain et al., 2014; shuangshuang et al., 2016). a smaller number of more detailed studies have provided insights into the frequency of occurrence and variation in expression of the parastyle in different human populations. the frequency of occurrence of the parastyle has been estimated to vary from zero to 0.1% in first molars, 0.4 to 2.8% in second molars and 0 to 4.7% in third molars (kustaloglu, 1962). these data were obtained from analyses of material representing recent homo sapiens (whites, american blacks, melanesians, filipinos, hawaiians, middle easterners [kish], and native americans [southwest indians, northwest coast indians, peruvians]). kustaloglu (1962) found that the parastyle was more common in native americans than the other population groups (2.6%). a retrospective study of the parastyle in children abstract the aims of this study are to describe the frequency of occurrence and degree of expression of the parastyle in six different ethnic groups; to assess interand intra-observer errors when scoring the feature; and to compare the expression of the feature in a small number of twin pairs. dental casts were examined for evidence of the parastyle from samples available in the adelaide dental school. a dental plaque developed by katich & turner was used to standardize scoring. the highest percentage frequency of parastyle occurrence was found in a sample of european twins with a value of 1.7%. the buccal aspect of the mesiobuccal cusp of the permanent maxillary right second molar was the most common site for the parastyle. inter-observer reliability in scoring was lower than intra-observer reliability. in 10 pairs of twins (seven pairs of monozygotic [mz] twins and three pairs of dizygotic [dz] twins) only two pairs of mz twins showed concordance for presence of the parastyle. the expression of parastyles likely results from a complex interaction of genetic, epigenetic, and environmental influences during dental crown development. there may be a relationship between parastyles and supernumerary teeth that are occasionally located buccally to the maxillary molar teeth. *correspondence to: emeritus professor grant townsend murray barrett laboratory, 3rd floor, medical school south adelaide dental school the university of adelaide grant.townsend@adelaide.edu.au 4 dental anthropology 2018 │ volume 31 │ issue 01 aged two and eight years looked at factors relating to parastyle expression, including unilateral versus bilateral positioning in the dental arch, its frequency in both males and females, and its occurrence in primary and secondary dentitions (nagaveni et al., 2017). in conclusion, the authors noted the parastyle was extremely rare in the primary dentition and that findings were inconclusive as to the other areas under review. importantly, the difficulty in scoring the parastyle and the need to provide a more accurate method of measuring the feature were emphasized (nagaveni et al., 2017). the aims of this study are to describe the frequency of occurrence and degree of expression of the parastyle within and between six different ethnic groups; to assess interand intra-observer errors when scoring the feature; and to compare the expression of the feature in a small number of twin pairs. our specific objectives are as follows: (1) make comparisons of the frequency of occurrence and degree of expression of the parastyle between primary and permanent dentitions of the same individuals (based on a study sample of twins); (2) compare expression on the first, second and third molars; and, (3) make comparisons between maxillary and mandibular molar teeth, as well as between right and left sides and between males and females. another objective is to assess interand intra-observer errors when scoring the feature to determine the usefulness of the plaque developed by katich and turner when examining the parastyle. a final objective is to explore the possible roles of genetic, epigenetic and environmental influences on observed variation of the parastyle by comparing the expression of the feature in a small number of twin pairs. finally, some thoughts about the etiology of the feature and its relationship to supernumerary molar teeth are provided, based on a threshold model of dental expression (brook, 1984; brook et al., 2014a, b). materials and methods dental casts representing both sexes were examined for evidence of the parastyle from samples of six different ethnic groups available in the murray barrett laboratory, adelaide dental school, the university of adelaide, by a single trained observer (gs). the frequency of occurrence and degree of expression of the trait were calculated for each of the ethnic groups. casts showing the presence of a parastyle were selected for further study. the dental plaque developed by katich & turner in 1974 (turner et al., 1991) was used to standardize scoring of the feature and to determine degrees of expression (fig. 1). reference was also made to written descriptions of the appearance of the parastyle, ranging from a small pit to a large cusp-like structure, provided by turner et al. (1991). the reference plaque includes the following categories: 0 the buccal surfaces of cusps 2 and 3 are smooth. 1 a pit is present in or near the buccal groove between cusps 2 and 3. 2 a small cusp with an attached apex is present. 3 a medium-sized cusp with a free apex is present. 4 a large cusp with a free apex is present. 5 a very large cusp with a free apex is present. this form usually involves the buccal surface of both cusps 2 and 3. 6 an effectively free peg-shaped crown attached to the root of the third molar is present. this rare condition is not shown on the plaque. whilst reference to the plaque was useful in providing a standard for scoring, it only showed five variations of parastyle expression and was therefore limited in the information it provided. the method used in the production of the dental casts was uniform for all the groups studied. alginate impressions were obtained of the subjects’ dentitions figure 1. the dental plaque developed by katich and turner in 1974, used to standardize scoring of the parastyle and to delineate its degrees of expression. 5 dental anthropology 2018 │ volume 31 │ issue 01 table 1. prevalence of parastyles in different ethnic groups and these impressions were poured using dental stone according to the manufacturer’s specifications. after the dental stone had set, the impressions were removed from the casts and trimmed prior to examination. the australian aboriginal dental casts were obtained from a longitudinal growth study of central australian aboriginals conducted at yuendumu settlement in the northern territory of australia, between the years 1951-1972 (brown et al., 2009). the ages of the subjects ranged between 5 to 77 years, with most being teenagers. the sample totalled 405 subjects. the same method of dental cast production was followed for the following ethnic groups: malay malaysians, 293; chinese malaysians 196; indian malaysians, 253; and orang asli, 71. these casts were collected as part of a phd study that investigated dental variation in malaysian schoolchildren with application to human identification (khamis, 2005). the ages of the subjects ranged between 12 and 51 years, and the sample totalled 813 subjects. dental casts of twins of european ancestry and known zygosity, who are involved in an ongoing study of orofacial morphology and growth and oral health at the adelaide dental school, the university of adelaide, were also included in this study (hughes et al., 2014; townsend et al., 2015). a total of 620 subjects from cohort 1 were scored for parastyles with the casts of twin pairs sorted randomly and the operator blinded to zygosity. the twins were all of european ancestry and ranged in age from 6 to 63 years. the total number of dental casts examined in all of the samples was 1838. using the parastyle plaque of katich and turner, the question of intraand inter-observer reliability was assessed with three experienced observers scoring the feature twice. the period between each observer score was at least two weeks enabling an assessment of concordance/discordance to be performed. it also gave the observers the ability to assess the associated criteria for determining different degrees of parastyle expression. deliberately, the three operators who scored the parastyle, although being experienced dental anthropologists, had no training together prior to each scoring the feature independently, so that the value of the plaque as a means of standardising across different observers could be investigated. results the frequencies of occurrence (prevalence) of the parastyle in the six different ethnic groups are presented in table 1. table 1 shows that the highest percentage frequency of parastyle occurrence was in the sample of european twins with a value of 1.6%. this was followed by the australian aboriginal sample with a frequency of 1.5%. the malay malaysians and indian malaysian groups showed fewer parastyles with only 0.3-0.4% of individuals displaying the trait, while no chinese malaysians were found to display the feature. the orang asli group result was 1.4% but the sample size was relatively small. the degrees of expression of the parastyle in the different study samples are shown in table 2 and some examples of the expression of the feature are provided in figure 2. only one individual (t234a) showed evidence of the parastyle in the primary dentition, with the feature being displayed on the primary maxillary right first molar. across all ethnic groups, the buccal aspect of the mesiobuccal cusp of the permanent maxillary right second molar was the most common site for the parastyle, with 13 observations. other teeth that showed the trait were the permanent maxillary right first molar (score: 1), permanent maxillary left second molar (score: 6), permanent maxillary right third molar (score: 1), and the deciduous maxillary right first molar (score: 1). given that most of the subjects included in this study were children or young adults there were few cases where third molars could be scored. using the katich and turner plaque, degrees of expression of the parastyle ranging from scores of 1 to 6 were recorded. there were similar numbers of males and females displaying evidence of the parastyle (11 males and 8 females). scores for parastyle expression that highlight intraand inter-observer reliability are given in table 3. within observers, there was no difference that was greater than one grade between the first and second scores. the difference in scoring between observers was never greater than two grades. in 17 cases, there were scoring differences noted between the three observers. this greater difference between observers’ scores occurred seven times. scorer 1 displayed four ethnic group n present % australian aboriginal 405 6 1.5 malay malaysian 293 1 0.3 chinese malaysian 196 0 0.0 indian malaysian 253 1 0.4 orang asli 71 1 1.4 european twins 620 10 1.6 6 dental anthropology 2018 │ volume 31 │ issue 01 different scores from scorers 2 and 3, scorer 2 displayed four different scores from scorers 1 and 3, and scorer 3 displayed nine different scores from scorers i and 2. with regard to the sample of twins of european ancestry, after scoring one member at random from each pair of twins, the co-twins of all those twins who displayed the parastyle were examined. table 4 shows that in the 10 pairs examined (seven pairs of mz twins and three pairs of dz twins), only two pairs of mz twins showed concordance for presence of the parastyle. in one of these pairs (t256), both members of the pair not only showed evidence of parastyles in their maxillary molars but also displayed protostylids on their permanent lower first molars. discussion when comparing the prevalence of the parastyle between ethnic groups under investigation it is interesting to note that two distinct groupings were evident. the malaysian groups showed fewer parastyles than either the australian aboriginals or the european twins, although the sample sizes of the malaysians were smaller. it is acknowledged that the inclusion of both members of twin pairs could have increased the prevalence estimates in this group if there was evidence of concordance between mz co-twins for parastyle occurrence. however, only two pairs of mz twins showed concordance for the feature. the malaysian groups conformed reasonably closely with the values for parastyle occurrence on permanent molars reported by kustaloglu (1962) that ranged from 0.1% 4.7%. scott et al. (2018) provide a table of paramolar tubercle frequencies compiled from the c.g. turner ii database for over 9000 individuals distributed across 23 geographic groupings. the world average for all table 2. frequency of occurrence and degree of expression of parastyles in different ethnic groups ethnic group tooth affected degree sex australian aboriginal ∆9 17 2 m ∆17 17 5 m ∆72 17, 18 3, 3 f ∆119 17 2 m ∆338 17 5 f ∆578 17 2 m malay malaysian mm 165 17, 27 2 m orang asli oa 3 17 2 m indian malaysian im 105 17 2 f european twins t67b 17 3 m t85b 17, 27 5, 5 m t136b 27 5 m t163b 17 2 m t192b 27 4 f t226a 27 4 f t234a 54 3 f t256a 16, 26 1 f t262b 27 5 m t304b 17 2 m figure 2. some examples of the expression of the parastyle. upper left australian aboriginal male, ∆17, grade 5 on tooth 17; upper right indian malaysian female, im 105, grade 2 on tooth 17; lower left twin t85b male, grade 5 on tooth 17; lower right twin t234a female, grade 3 on tooth 54. 7 dental anthropology 2018 │ volume 31 │ issue 01 groups was 1.58%. relative to the groups in this study, australians had incidence prevalence of 1.8%, europeans 2.17% (western) and 0.63% (eastern), east asians 1.6%, and southeast asians 2.27% and 1.75%, for early and recent groups respectively. these values are in general accord with our findings on recent populations. as the trait generally varies between one and three percent, further studies of large samples are needed to determine whether there are significant differences in parastyle frequency and degrees of expression between different human populations. the finding that most of the parastyle observations occurred on the right side of the dentition suggests that there could be some directional asymmetry involved, although there is very little evidence to support consistent expression of directional asymmetry in any dental crown morphological features (scott et al., 2018). there did not appear to be any significant difference in parastyle frequency of occurrence between the sexes. table 2 shows that a similar number of males and females displayed the feature, and that the size and shape of the feature did not appear to differ between males or females, so sexual dimorphism was not evident in our study. however, given the very small number of individuals who show parastyles, very large sample sizes are needed to detect systematic differences between the sexes. it was evident in the scoring of the parastyle that difficulties arose in determining the size of the feature. we suggest a new plaque be developed that has the capacity to improve accuracy in scoring. the present plaque provides only one example of the degree of parastyle formation in the six categories mentioned. the fact that the teeth used to construct the plaque vary widely in terms of their size and shape makes it difficult to score the relative size of the parastyle when ethnic group cast id location scorer 1 scorer 2 scorer 3 1st 2nd 1st 2nd 1st 2nd australian aboriginal ∆9 17-mb 2 2 2 2 2 2 ∆17 17-mb 5 5 5 5 5 5 ∆72 17-mb 3 3 3 3 2 1 18-mb 3 3 3 3 5 5 ∆119 17-mb 2 2 2 2 1 2 ∆338 17-mb 5 5 5 5 5 5 ∆578 17-mb 2 2 2 3 2 1 malay malaysian mm 165 17-mb 2 2 2 2 2 2 27-mb 2 2 3 3 3 3 orang asli oa 3 17-mb 3 3 2 3 1 1 indian malaysian im 105 17-mb 2 2 2 2 2 2 european twins t67b 17-mb 3 3 4 5 3 3 t85b 17-mb 6 6 5 5 5 5 27-mb 6 6 5 5 5 5 t136b 27-mb 4 5 5 5 5 4 t163b 17-mb 2 2 3 4 2 2 t192b 27-mb 3 3 4 4 4 4 t226a 27-mb 4 4 4 4 4 4 t234a 54-mb 3 4 3 3 2 2 t256a 16-mb 1 1 1 1 2 2 t262b 27-mb 4 4 5 5 4 5 t304b 17-mb 2 2 2 2 1 1 table 3. intraand inter-observer reliability for scoring parastyles 8 dental anthropology 2018 │ volume 31 │ issue 01 extrapolated to other teeth that are under investigation. we suggest providing more than one example of the categories of the parastyle to highlight the extent of the variation within a category. it would also be helpful to have stereoscopic images of these different variations in digital form that could be viewed from different perspectives using computer technology. as shown in table 4 there were seven mz twin pairs and three dz pairs examined, with only two pairs of mz twins showing concordance for parastyle occurrence. given that mz twins share all of their genes, while dz twin pairs, on average, share only 50% of their genes, one would expect a higher concordance of parastyle occurrence within mz pairs if there was a strong genetic basis to the feature. the lack of concordance suggests that variation in parastyle occurrence and expression is likely to reflect mainly epigenetic and/or environmental influences. the tendency for the strongest expression of the parastyle to have characteristics similar to supernumerary teeth that form buccally to the permanent molars (i.e., apparently with separate crown formation although possibly fused roots), suggests that the feature may conform to the upper end of the multifactorial unifying aetiological model of dental development (brook, 1984; brook et al., 2014a, b) that posits a relationship between tooth size, shape, and presence or absence. it is possible that the strongest expression of the parastyle falls just to one side of a threshold above which a supernumerary molar tooth is formed. further studies of the associations between tooth size, parastyle expression and supernumerary tooth prevalence within individuals would help to clarify this issue. one of the authors (grs) has noted structures similar to paramolar tubercles on the lingual surface of the maxillary molars and both buccal and lingual surfaces of the mandibular molars. buccal manifestations on the lower molars are not protostylids, which are expressed in a constant position on the buccal surface of the protoconid and are less pronounced than lower molar ‘pseudo-paramolar’ tubercles. these diverse expressions may represent different developmental processes: some of the appearances are compatible with fusion of the molar tooth germ with a buccal supernumerary tooth germ, while others may be additional cusps arising from additional enamel knots. the presence of both parastyles and protostylids in both members of one of the concordant mz twin pairs provides some evidence for an association between these two features that may be based on underlying genetic influences. however, this was only one pair, so care is needed in considering the significance of this observation. conclusions this study provides further insights into the frequency of occurrence and degree of expression of the parastyle in several human populations that have not been reported previously. one of the difficulties in scoring parastyles reliably lies in the nature of the system of scoring devised by katich and turner, and we have made some suggestions to improve the classification of this feature. it appears that the parastyle, with its varying degrees of expression, results from a complex interaction of genetic, epigenetic, and environmental influences during dental crown development. there may also be a relationship between parastyles and supernumerary teeth that are located buccally to the maxillary molar teeth. acknowledgments the dental casts used in this study are housed in the murray barrett laboratory, adelaide dental school, the university of adelaide. dr mohd khamis collected the malaysian casts as part of a phd study with support of a grant from universiti sains malaysia. the aboriginal casts were collected mainly during the 1950s and 60s at yuendumu with support from the national institute of dental research grant de0203407 from the national institute of dental research, national institute of health, bethesda, maryland. the dental casts of twins form part of an ongoing study of twin id mz/ dz co-twin id p/a concordant/ discordant t67b dz t67a a d t85b mz t85a a d t136b mz t136a a d t163b mz t163a a d t192b dz t192a a d t226a dz t226b a d t234a mz t234b p c t256a mz t256b p c t262b mz t262a a d t304b mz t304a a d p=present, a=absent table 4. expression of parastyle in twin pairs 9 dental anthropology 2018 │ volume 31 │ issue 01 dental development and morphology at the adelaide dental school supported by the national health and medical research council (nhmrc) of australia, the australian dental research foundation, the financial markets foundation for children and colgate oral care australia. references bolk l. (1916). problems of human dentition. am j anat, 19, 91-148. brook ah. (1984). a unifying aetiological explanation for anomalies of human tooth number and size. arch oral biol, 29, 373-378. brook ah., m, brook o donnell m, hone a, hart e, hughes te, smith rn, townsend gc. (2014a). general and craniofacial development are complex adaptive processes influenced by diversity. aust dent j, 59 (1 suppl), 13-22. brook ah, jernvall j, smith rn, hughes te, townsend gc. (2014b). the dentition: the outcomes of morphogenesis leading to variations in tooth number, size and shape. aust dent j, 59 (1 suppl), 131-142. brown t, townsend gc, pinkerton sk, rogers jr. (2011). yuendumu: legacy of a longitudinal growth study in central australia. adelaide: university of adelaide press. dahlberg aa. (1945). the paramolar tubercle. am j phys anthropol, 3, 97-103. duddu mk, muppa r, bhupatiraju p, waghray s, kulkarni vk. 2012. unusual occurrence of paramolar tubercle on deciduous upper first molar – report of two cases and literature review. int j oral med sci, 11, 54-56. hughes te, townsend gc, pinkerton sk, bockmann mr, seow wk, richards lc, mihailidis s, ranjitkar s, lekkas d. (2014). the teeth and faces of twins: providing insights into dentofacial development and oral health for practising oral health professionals. aust dent j, 59 (1 suppl), 101-116. jain p, ananthnarayan k, ballal s, natanasabapathy v. (2014). endodontic management of maxillary second molars fused with paramolar tubercles diagnosed by cone beam computed tomography. 2014. j dent (tehran uni med sci), 11, 726-732. kustaloglu oa. (1962). paramolar structures of the upper dentition. j dent res, 41, 75-83. khamis mfb. (2005). dental variation in malaysian populations with application to human identification. phd thesis. the university of adelaide. 2005. nabeel s, danish g, hegde u, gehlot pm, (2012). parastyle: clinical significance and management of two cases. int j oral max path, 3, 6164. nagaveni nb, umashankara kv, radhika nb, praveen reddy b, manjunath s. (2010). maxillary paramolar: report of a case and literature review. arch orofacial sci, 5, 24-28. nagaveni nb, umashankara kv, poornima p, subba reddy vv. (2017). paramolar tubercle (parastyle) in primary molars of davangere (india) children: a retrospective study. int j oral health sci, 4, 18-22. parolia a., kundabala m, dahal m, mohan m, thomas ms. (201)1. management of supernumerary teeth. j con dent, 14, 221-224. scott gr, turner cg ii, townsend gc, martinontorres m. (2018). the anthropology of modern human teeth: dental morphology and its variation in recent and fossil homo sapiens. cambridge: cambridge university press. shuangshuang r, miao l, yu y, zhang x, zhu m, sun w. (2016). fusion between maxillary second molar and a supernumerary tooth: a case report. int j clin exp med, 9, 20314-20318. townsend g.t., pinkerton sk, rogers jr, bockmann mr, hughes te. (2015). twin studies: research in genes, teeth and faces. adelaide: university of adelaide press. turner c. g., nichol c. r., and scott g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, and larsen cs, editors. advances in dental anthropology (pp. 13-31). new york: wiley-liss. 21 dental anthropology 2022 │ volume 35│ issue 01 tooth enamel is the densest, most resilient tissue in the human body (hillson, 1996). as a result, human teeth typically can survive a wide range of environments, making them a rich source of information for bioarchaeologists gathering data on human behavior. indeed, the importance of the dentition in bioarchaeology relates to the fact that it informs on human evolution, diet, growth and development, migration, identity, and disease (scott and turner, 1988; hillson, 1996). since the oral cavity has direct contact with both the external and internal environment, examination of oral disease in the dentition enhances our understanding of the differences in foodways between and within cultures. dental disease provides significant information concerning ancient diet and cultural practices, as well as the influence of diet on pathological conditions of the dentition (konig, 2000; moynihan, 2005). dental disease is sometimes used as a proxy for understanding oral health, but the inconsistency in defining the term health has led researchers to move away from the umbrella term that includes unknowable factors (e.g., psychosocial aspects) and instead focus on dental disease as indicated by specific conditions (e.g., dental caries; pilloud and fancher, 2019). although teeth are valuable indicators of disease and life history, as well as a source of demographic and cultural data, several studies highlight the prevalence of sample bias arising from antemortem and postmortem teeth loss (e.g., lukacs, 1995; erdal and duyar, 1999). loose or missing teeth are extremely common in bioarchaeological samples, and a review of the literature has shown inconsistent methods in dealing with the consequent bias during data collection and analysis. the study of dental pathology is further complicated by the varying preservation rates of the multiple gaps in information: what missing teeth mean in bioarchaeology laura e. cirillo 1* and eric j bartelink 2 1 department of anthropology, university of nevada, reno 2 department of anthropology, california state university, chico abstract previous bioarchaeological analysis of postmortem tooth loss (pmtl) has failed to recognize the potential influence of diseased dental tissue on tooth retention after death. because tooth loss from a traditional taphonomy prospective is treated simply as missing data, demographic studies are potentially influenced by underestimations of disease prevalence. to investigate the association of tooth loss and dental disease, data on the pathological conditions observed in the tissues were collected on a sample of teeth from 771 individuals. by analyzing the evidence of disease in the bone and dental tissues immediately surrounding empty alveolar sockets suggestive of pmtl, trends in the presence of diseased tissue and retention of a tooth emerged. when compared to teeth retained after death, pmtl sockets were 15.3% less likely to retain neighboring teeth and 21.5% less likely to have neighboring teeth that showed no signs of carious or periapical lesions. the results suggest that the traditional explanation of susceptibility to loss due to the exposure and morphology of single-rooted, anterior teeth does not sufficiently explain the causes of pmtl in many cases. rather, it would be more accurate to consider pmtl, in part, as an advanced symptom of dental disease when interpreting missing teeth in the bioarchaeological record. *correspondence to: laura e. cirillo department of anthropology university of nevada, reno e-mail: misslauracirillo@gmail.com this paper was the recipient of the albert a. dahlberg prize awarded by the dental anthropology association in 2021. keywords: postmortem tooth loss, dental pathology, dental disease 22 dental anthropology 2022 │ volume 35│ issue 01 tissues that make up the dentition. teeth are enclosed in some of the most fragile bone, the alveolar sockets of the maxilla and mandible. that brittle enclosure is susceptible to much more damage in archaeological contexts than the teeth themselves, and results in significant tooth loss after death. this article explores the potential influence of missing teeth on the analysis of skeletal samples utilizing a statistical examination of patterns in dental pathology to infer what information may have been lost from teeth missing postmortem. we will focus on patterns found in various samples that exhibit missing teeth to potentially correct the underrepresentation of oral disease prevalence and will propose steps to correct possible biases from data loss. taphonomy of tooth loss tooth loss after death can occur through tissue loss during natural processes of decomposition. the conical shape of roots, especially of anterior teeth, makes teeth susceptible to coming loose from their sockets (oliveira, melani, antunes, freitas, and galvão, 2000). the burial environment also affects decomposition of the soft and hard tissues and influences postmortem tooth loss (pmtl). in addition to tissue shrinkage and decomposition during skeletonization, handling of the remains during excavation, examination, transport, and storage can contribute to the dislodging and loss of teeth (ðurić, rakočević, and tuller, 2004; oliveira et al., 2000). a common storage method for crania, for example, is to rest them on their mandibles for stability, which may damage maxillary teeth (oliveira et al., 2000). the postmortem interval, root morphology and number, and excavation methods all influence the rate of pmtl (tibbett and carter, 2008). recent bioarchaeological literature emphasizes the need for careful excavation to ensure the complete recovery of the dentition. because skulls are often recovered with teeth missing, it is important to maximize tooth recovery through careful excavation methods. loose teeth that are outside of expected anatomical position may not be recognized during excavation, especially if burial context is not carefully examined (ðurić et al., 2004). the lack of standard excavation methods has affected the way human remains are analyzed in both bioarchaeological and forensic contexts (evis, hanson, and cheetham, 2016; haglund, 1997). recent research suggests that a stratigraphic excavation method results in more evidence recovery than an arbitrary level method, especially in small element recovery rates and with fewer bones categorized as unassociated (evis et al., 2016, tuller and ðurić, 2006). the recovery of disarticulated material, such as dental remains, is crucial for constructing biological profiles and paleoepidemiology research (tuller and ðurić, 2006). pathology of tooth loss although pmtl in bioarchaeological contexts is often due to carelessness during excavation, the amount of effective soft tissue holding a tooth in its anatomical position also is an important factor to consider (ðurić et al., 2004). periodontal disease influences the integrity of the periodontal ligament that helps anchors the cementum to the alveolar bone and the gingiva, and therefore contributes to the potential for teeth to be easily dislodged postmortem (ðurić et al., 2004; meller, urzua, moncada, and von ohle, 2009). oral disease can be introduced through several different pathways and can affect both the soft and hard tissues of the oral cavity. teeth are at risk for loss through infection of the adjacent tissues or due to trauma to the enamel structure. the three main pathological conditions of interest are dental caries (carious lesions in the tooth), periapical lesions (lytic lesions in the alveolar bone), or occlusal tooth wear (loss of tooth enamel). these pathological conditions threaten the integrity of the tissues involved, therefore compromising the tooth as a unit. the most significant outcome, no matter the pathogenesis, is loss of the overall tooth. once a tooth is lost, both the soft tissue and the surrounding alveolar bone begin to heal. within eight weeks of tooth loss, most of the socket is filled with remodeled bone (larjava, 2012). this remodeling reaches the alveolar crest within three to four months (shiroma, terrado-naguinlin and zuerlein, 2019), and continues for around six months, with variation based on the location and presence of neighboring teeth (larjava, 2012). but the successful healing of a single tooth socket does not spare the rest of the oral cavity from a similar fate. typically, the interaction of the environment and the tissues of the mouth are not confined to one tooth alone; oral pathological conditions often have multiple causes, and more than one tooth may be affected by the same disease process. as the dental tissues respond and react at different rates, moving beyond an individual tooth and considering the implications of oral pathology creates a better sense of the physical indications of an individual’s overall health. from there, population level analysis provides perspective on overall disease prevalence in a past community. although rarely recorded beyond an inventory, 23 dental anthropology 2022 │ volume 35│ issue 01 tooth loss is often included in the larger interpretations of prehistoric dentitions (costa, 1980; lukacs, 2007). the loss of data from absent teeth is one of the most prevalent concerns in the bioarchaeology dental disease literature (cucina and tiesler, 2003). potential underestimation of dental caries rates has been acknowledged in calculations of disease prevalence in samples with high rates of missing teeth (lukacs, 1995; littleton and frolich, 1993). analyzing when tooth loss took place (e.g., antemortem or postmortem), and the underlying factors that led to loss of that tooth, can be difficult to determine. establishing when tooth loss occurred depends on the remaining alveolar bone and the degree to which it has remodeled. antemortem tooth loss (amtl) of the permanent dentition is associated with advanced stages of dental disease. antemortem tooth loss has several potential causes: caries, pulpitis, or periodontitis resulting from infection of the tooth and the surrounding tissues, or trauma (costa, 1980; hillson, 1996; indriati and buikstra, 2001; larsen, 1995). the bias in data collection that results from amtl has long been acknowledged, primarily in the context of studying rates of dental caries, but only a few researchers have attempted to correct for this loss in data (hardwick, 1960; brothwell, 1963; powell, 1985; kelley, levesque, and weidl, 1991; lukacs, 1995; gagnon and wiesen, 2013). most successfully, lukacs proposed the “caries correction factor,” which derives from the prevalence of pulp exposure due to carious lesions versus attrition observed in the sample. by creating a sampleor population-specific equation for calibrating caries rates, the correction factor considers the relationship between carious lesions and amtl (lukacs, 1995). this focus on the effects and interpretations of amtl has led to increased incorporation of tooth loss data in dental inventories and oral disease assessments (nelson, lukacs, and yule, 1999; cucina and tiesler, 2003). postmortem tooth loss, on the other hand, has been much more ignored in the bioarchaeological literature and often treated as missing data. although it is commonly acknowledged as a data collection bias, it is rarely addressed outside of the need for careful excavation when exhuming human remains (tuller et al., 2004). as discussed below, a tooth lost either antemortem or postmortem is often an indication of the subtle changes in the surrounding tissues, and consequently the disease of the overall oral cavity, rather than solely an unfortunate consequence of taphonomic processes. this study examines samples that exhibit different patterns of pmtl and explores how these patterns influence the underrepresentation of oral disease prevalence and how to correct for this bias. materials and methods the dentition of 771 individuals was inventoried and each tooth or empty tooth socket was assessed for wear and pathological conditions. the methods follow bartelink’s (2006) modification of the scoring system presented in buikstra and ubelaker’s (1994) standards for data collection from human skeletal remains, to provide consistency between the new data collected and bartelink’s 2004-2012 collection of dental data for the final pooled sample. when the tooth was present for observation, dental caries was then scored by location on the tooth and dental wear was recorded using the smith (1984) system for anterior teeth and premolars and the scott (1979) system for molars. when assessing teeth for dental caries, all potential lesions were probed using a dental pick and evaluated using a 10x magnification hand lens. for the context of this research, tooth condition was recorded as either present in occlusion, amtl, or pmtl. all other cases were excluded. neighboring tissues in this context were represented by an examination of the teeth immediately mesial and distal to the selected tooth and the alveolar bone that surrounded those teeth. in the case of the third molar, there was no distal tooth, so the second molar was its only neighbor. as dental disease is not often isolated to a single tooth, we hypothesize that the condition of the tooth was affected by the presence of carious lesions in the neighboring teeth and/or by the presence of periapical lesions in the neighboring tissues, given that periapical lesions can weaken the tissues holding a tooth within the alveolar bone. to be marked as “observable,” a tooth must have been present and in the occlusal plane, with greater than 2 mm of vertical enamel surrounding at least 50% crown circumference, eliminating overly worn and loose teeth. subadults were removed from the original sample to ensure all individuals had permanent dentition. individuals with tooth loss due to potential congenital absence (judged by examining tooth positions relative to tooth types) were also excluded for ease of comparison. the pooled data set consisted of 771 adult individuals from late holocene (5000-200 bp) archaeological sites in pre-contact california, which was created using the dental inventories and pathology assessments. the sample population was represented by individuals from ca-ala-307, -309, 24 dental anthropology 2022 │ volume 35│ issue 01 328, and -329, sites located near the shoreline of the san francisco bay, the ancestral homelands of the ohlone tribe, and from ca-sac-06, -43, -60 and sjo-68, -142, and -154, sites located in the central valley, the ancestral homelands of the plains miwok tribe. this research used a combination of new data collected for this study and previously collected data from bartelink’s (2006) dissertation research. all dentitions were examined at uc berkeley’s phoebe a. hearst museum of anthropology, where they are currently curated. permission to collect data were provided by the museum’s curator and nagpra committee. after instances of pmtl with all observable neighboring teeth were isolated, the collection consisted of two groups: (i) a control group, where the primary tooth examined was present and in occlusion, and (ii) an experimental group, where the primary tooth examined was absent postmortem. teeth were pooled from right and left sides of the mandible and maxilla. tooth counts of the total sample are presented in table 1. results the data analysis first considers whether instances of pmtl were more often associated with surrounding teeth or neighboring tissues that had already experienced amtl. the presence or absence of the neighboring teeth was compared between each primary tooth that was present and in occlusion, and those recorded as pmtl. after organizing by tooth type (table 2), the percentage of primary teeth with both neighboring teeth present was lower in every tooth group when the primary tooth being examined was lost postmortem. the smallest difference was a 2.3% decrease in third molars, and the largest difference was a 25.4% decrease in the fourth premolar. the average difference between having all neighboring teeth present between control teeth and pmtl teeth was a 15.3% decrease when all tooth types were considered. the visual representation (figure 1) shows that the percent difference was especially high for posterior teeth. the average difference between anterior tooth types was a 12.3% decrease. the average in posterior teeth was a 17.1% decrease (20.8% when third molars were excluded). when third molars were excluded for not meeting the criteria of having two neighboring teeth, instances of having one neighboring tooth present and the other absent were most often seen in the posterior teeth. in this analysis, greater than 20% of pmtl affected second molars, first molars, fourth premolars, and third premolars had one present and one absent neighbor. although the change in percentage of teeth with two neighbors present was not as great between control and pmtl incisors, all anterior teeth showed a consistent decline in percent of present neighbors in each experimental group. rather than a similarly high prevalence of the one present and one absent neighbor alternative, as was seen in posterior teeth, all the anterior teeth were more affected by amtl on both sides. dental caries and neighboring tissues to understand the effects of specific dental pathological conditions on the prevalence of pmtl, an analysis of the neighboring tissues was also conducted to see how carious lesions and periapical lesions are associated with compromised surrounding tissues and overall tooth loss (table 3). in this analysis, the control tooth was present without evidence of carious lesions, and the experimental tooth was again one in the same position that was lost postmortem. although all analyses showed that it is rare to have both neighboring teeth affected by the same pathological condition, in the case of carious lesions, there were two cases seen on canine teeth. both control and experimental groups showed few differences when both neighboring teeth were present. the smallest difference in percent of all neighboring teeth with no caries was 0.8% in second molars, while the greatest difference was only 7.8% in first molars. neighboring teeth of experimental groups for third premolars, canines, and both incisors all displayed no caries. consistent with the literature on dental caries, posterior teeth were more affected than anterior teeth. most teeth showed a slight decrease in caries prevalence in the surrounding tissues in the experi tooth # control (present) # experimental (pmtl) m3 930 166 m2 815 20 m1 924 12 p4 854 118 p3 765 78 c 650 74 i2 522 113 i1 476 73 table 1. research sample size by tooth and condition. 25 dental anthropology 2022 │ volume 35│ issue 01 tooth condition all neighboring teeth present (%) 1 tooth present, 1 tooth amtl (%) all neighboring teeth amtl (%) m3 present 93.9 4.9 n/a pmtl 91.6 8.4 n/a m2 present 92.4 6.1 1.5 pmtl 75.0 25.0 0.0 m1 present 94.4 3.4 0.0 pmtl 75.0 25.0 0.0 p4 present 96.6 3.3 0.5 pmtl 71.2 21.2 5.0 p3 present 97.8 2.2 0.0 pmtl 76.9 21.8 1.3 c present 97.5 1.8 0.6 pmtl 78.4 9.5 12.2 i2 present 97.7 2.3 0.0 pmtl 87.6 7.1 5.3 i1 present 99.6 0.4 0.0 pmtl 91.8 4.1 4.1 table 2. prevalence of all three neighboring tissue categories. figure 1. visual comparison of the prevalence of neighboring tissue categories. 26 dental anthropology 2022 │ volume 35│ issue 01 mental group. control groups for third molars, second molars, third premolars, canines, and all incisors each had a higher percent of neighbors with carious lesions than their experimental counterparts. when isolated to show teeth that had one neighboring tooth present and one with amtl, carious lesions were only observed in posterior teeth, consistent with existing literature. caries rates were again higher in the control group, with a large increase from 80% present second molars with the observable neighbor displaying no caries, to 100% in the neighbors of the pmtl second molars. there was no caries-focused analysis of the difference between present and pmtl teeth with both neighbors absent because, unlike periapical lesions that affect tissue other than on the actual tooth, neighboring teeth necessarily must be present to observe dental caries lesions. periapical lesions and neighboring tissues following the framework of the caries-focused examination of neighboring teeth, the neighboring tissues (both tooth and alveolar socket) were examined for periapical lesions. table 4 shows a comparison of the prevalence of periapical lesions when both neighboring teeth were present. the experimental group in every tooth group had more periapical lesions in the neighboring tissues than the control group, except for first molars which had a 1.0% increase in prevalence of no periapical lesions when the primary tooth was recorded as pmtl. the smallest change was a 0.4% decrease in central incisors, and the greatest change was the 18.4% decrease in lateral incisors. generally, periapical lesions had a greater influence on non-molar teeth, which was particularly apparent for periapical lesions in teeth with one neighboring tooth present and one lost antemortem. although there is no particular pattern in the posterior teeth (i.e., minimal differences observed between control and experimental groups), the anterior teeth and fourth premolars show a consistent decrease in unaffected neighboring tissue in the experimental groups (as depicted in figure 2). the difference between all control and experimental groups shows an average 27% decrease (23.5-33.3%, min-max). there was not enough data to see a pattern in instances where both neighboring teeth were absent, but the inability to gather enough instances of control data to provide a comparison may be telling. no data showed pmtl with two amtl neighbors, with a maximum count of nine when divided by tooth number, and with no molars fitting these criteria. with few exceptions, this data set failed to show a present tooth that had two amtl neighbors. twelve instances were recorded in second molars, four in fourth premolars, and four in canines. all other teeth had no instances of this tooth loss pattern. it is possible that some oral pathological conditions may not affect neighboring tissues but are more limited to the individual tooth. given the expectation that missing neighbors will compromise the maintenance of the primary tooth being analyzed, especially in the case of periapical lesions that affect tissues of the jaw as well as the tooth, it is not surprising that two missing neightooth condition all neighboring teeth no caries (%) 1 neighboring tooth with caries (%) 2 neighboring teeth with caries (%) m3 present 95.3 4.7 n/a pmtl 98.0 2.0 n/a m2 present 92.6 7.4 0.0 pmtl 93.3 6.7 0.0 m1 present 96.7 3.3 0.0 pmtl 88.9 11.1 0.0 p4 present 97.2 2.8 0.0 pmtl 96.4 3.6 0.0 p3 present 98.5 1.5 0.0 pmtl 100.0 0.0 0.0 c present 98.9 0.7 0.3 pmtl 100.0 0.0 0.0 i2 present 99.0 1.0 0.0 pmtl 100.0 0.0 0.0 i1 present 97.9 2.1 0.0 pmtl 100.0 0.0 0.0 table 3. prevalence of all three dental caries inventory categories. 27 dental anthropology 2022 │ volume 35│ issue 01 tooth condition no pl on all neighboring teeth (%) 1 neighboring tooth with pl (%) 2 neighboring teeth with pl (%) m3 present 96.8 3.2 n/a pmtl 94.1 5.9 n/a m2 present 93.0 7.0 0.0 pmtl 80.0 20.0 0.0 m1 present 99.1 0.9 0.0 pmtl 100.0 0.0 0.0 p4 present 94.1 5.7 0.2 pmtl 84.5 14.3 1.2 p3 present 99.9 0.1 0.0 pmtl 93.3 5.0 1.7 c present 99.1 0.9 0.0 pmtl 98.3 1.7 0.0 i2 present 99.2 0.8 0.0 pmtl 80.8 15.2 4.0 i1 present 98.9 1.1 0.0 pmtl 98.5 1.5 0.0 table 4. prevalence of all three periapical lesion inventory categories. figure 2. visual comparison of the prevalence of neighboring tissues exhibiting periapical lesions when one neighboring tooth is present and one is amtl. 28 dental anthropology 2022 │ volume 35│ issue 01 bors make the tissues less likely maintain a tooth. thus, a large enough control group sample was unavailable for this analysis. this was the only situation where the experimental sample was larger than the control sample. affected neighbors because multiple dental conditions can be present in the same individual (even on the same tooth) and would not be accounted for when analysis narrows to focus on a single pathological condition at a time, the scope of analysis was expanded to look at the effects of neighboring tissues affected by either caries or periapical lesions. this included amtl as an indicator of the final stage of either pathological condition, where the tooth could not be maintained in life. figure 3 shows the percentage of neighboring teeth for each tooth position (control) and pmtl, divided by no affected neighbors, one affected neighbor, or both neighbors affected. to be categorized as “affected,” a tooth or its surrounding tissue needed to display carious lesions, periapical lesions, be absent antemortem, or any combination of the three conditions. because third molars only have one neighboring tooth, they again could only be recorded as having one affected neighbor or no affected neighbors. there is a clear pattern in the visual comparison that pmtl is often surrounded by “affected” or tissues without any indication of disease. in the control groups, the tooth had two unaffected neighbors an average of 92.0% of the time (table 5). by contrast, the pmtl groups had only an average of only 70.5%. the smallest difference was between the control and pmtl groups for third molars (3.4%), while the largest difference was between the control and pmtl groups for first molars (36.0%). the pmtl group with the highest percent of two unaffected neighbors was the central incisor. if neighboring tissues do not contribute to its loss in a significant way, then retention of the central incisor is the least influenced by tissue health and tooth loss must be attributed to other, taphonomic factors. this is perhaps the most common taphonomic loss due to the instability of a single location at the anterior of the mouth (exposing it to maximum pressure in burial and collection storage). the difference in the distribution of one affected neighbor and both neighbors affected also showed an interesting pattern. non-molar teeth had a much greater percentage of two affected neighbors. the average of non-molar pmtl with two affected neighbors was 9.0% and varied from 6.0 to 12.0%. although it is common to see a difference between third molars and the other molars because of the unique single-neighbor quality and differfigure 3. visual comparison of the prevalence of “affected” neighboring tissues. 29 dental anthropology 2022 │ volume 35│ issue 01 ences in eruption times, this is one of the only comparisons from this research that showed variation between the second and first molars. they are typically assumed to have similar physical characteristics that make them susceptible to caries, but also are multi-rooted teeth, providing them similar connective stability. discussion the “neighboring tissues” test was designed to determine whether oral pathological conditions influenced pmtl versus solely taphonomic explanations. patterns between control teeth and pmtl indicate that the integrity of the surrounding tissues affects the retention of a tooth after death. although there were specific patterns associated with periapical lesions alone, the overall patterns indicated that dental caries does not affect the ability of the tissues to retain a tooth after death. when both neighboring teeth were present, most teeth showed a decrease in carious lesions in the surrounding teeth in the experimental (pmtl) group. this is contrary to the expectation that missing teeth would have more affected neighbors in the presence of any oral pathological condition. however, the experimental group presented more periapical lesions in the neighboring tissues than the control group. periapical lesions tended to have a greater effect on non-molar teeth. although there were specific patterns associated with the presence of dental periapical lesions as a solitary pathological condition, dental caries lesions did not affect the ability for the tissues to retain a tooth after death. to address tissues that have been impacted vs. not impacted by disease, rather than exclude compromising conditions by creating a false categorization that separates dental caries and periapical lesions, the data were lumped into an “affected tissues” test. this clear difference between control and experimental groups supports the research hypothesis that affected tissues are correlated with prevalence of pmtl. overall, the analyses conducted indicate that pmtl is often a consequence of pathological conditions rather than solely due to taphonomic damage. thus, it should be possible to adjust data related to pmtl in the same way amtl is corrected to generate more reliable caries rates. using indicators of disease in the surrounding tissues, the presence of a pathological condition in the missing tooth can potentially be inferred, adjusting prevalence rates in a skeletal sample. as with the caries correction factors for amtl, a sliding scale or population-specific method is needed. this would need to be calculated based on the integrity of the visible tissues and can only be accomplished if pmtl is considered a consequence of pathology, rather than simply the result of postmortem damage to the alveolar bone. more elaborate and precise observations need to be incorporated into the tooth condition all neighboring teeth unaffected (%) 1 neighboring tooth affected (%) 2 neighboring teeth affected (%) m3 present 88.3 11.7 n/a pmtl 84.9 15.1 n/a m2 present 78.8 17.7 3.5 pmtl 55.0 45.0 0.0 m1 present 94.4 5.6 0.0 pmtl 55.0 41.7 0.0 p4 present 88.8 10.1 1.2 pmtl 62.7 28.0 9.3 p3 present 96.2 3.5 0.0 pmtl 69.2 21.8 9.0 c present 95.5 3.5 1.0 pmtl 75.7 12.2 12.2 i2 present 96.6 3.1 0.3 pmtl 69.9 21.2 8.8 i1 present 97.1 2.1 0.8 pmtl 88.7 5.6 5.6 table 5. prevalence of all three “affected” inventory categories 30 dental anthropology 2022 │ volume 35│ issue 01 inventory methodology. current inventory recommendations only consist of practicing extra care while analyzing the fragile alveolar bone and recording missing teeth as “absent, without alveolar bone remodeling, postmortem tooth loss”. there is no current method for recording teeth that are loose and replaced in their crypt, other than recording them as present, which does not distinguish them from teeth that are maintained in the crypt by supporting tissues. a new category should be added to the inventory methods to reflect this difference when inventorying teeth. if teeth are “absent through postmortem tooth loss” or “present but loose/removable from crypt without force”, observations can be made to examine the empty crypt for signs of pathology in the tissue. a closer look during analysis using clues of the surrounding tissue may help indicate the health of the missing teeth, given our improved understanding of how pathological conditions specifically affect tooth retention. collecting this data will permit a wider range of calculations of dental pathology prevalence for data sets. references bartelink, e. (2006). resource intensification in precontact central california: a bioarchaeological perspective on diet and health patterns among huntergatherers from the lower sacramento valley and san francisco bay (doctoral dissertation). texas a&m university, college station, texas. brothwell, d. (1963). the macroscopic dental pathology of some earlier human populations. in: dental anthropology. d. brothwell (ed.). london: pergamon press. buikstra, j.e, & ubelaker, d.h. (1994). standards for data collection from human skeletal remains. proceedings of a seminar at the field museum of natural history (arkansas archeological report research series). costa, r. l. (1980). age, sex, and antemortem loss of teeth in prehistoric eskimo aamples from point hope and kodiak island, alaska. american journal of physical anthropology, 53, 579-587. cucina, a., & tiesler, v. (2008). dental caries and antemortem tooth loss in the northern peten area, mexico: a biocultural perspective on social status differences among the classic maya. american journal of physical anthropology, 122(1), 1-10. ðurić, m., rakočević, z., & tuller, h. (2004). factors affecting postmortem tooth loss. journal of forensic science, 49(6). erdal, y. s., & duyar, i. (1999). a new correction procedure for calibrating dental caries frequency. american journal of physical anthropology, 108(2), 237-240. evis, l.h., hanson, i., & cheetham, p.n. (2016). an experimental study of two grave excavation methods: arbitrary level excavation and stratigraphic excavation. star: science & technology of archaeological research, 2(2), 177-191. gagnon, c.m. & wiesen, c. (2013). using general estimating equations to analyze oral health in the moche valley of peru. international journal of osteoarchaeology, 23, 557-572. haglund, w.d. (1997). scattered skeletal human remains: search strategy considerations for locating missing teeth. in: forensic taphonomy: the postmortem fate of human remains. boca raton: crc press. hardwick, j.l. (1960). the incidence and distribution of caries throughout the ages in relation to the englishman’s diet. british dental journal, 108, 9. hillson, s. (1996). dental anthropology. cambridge university press: cambridge, uk. hillson, s. (2005). teeth (second edition). cambridge university press: cambridge. indriati, e. & buikstra, j.e. (2001). cocoa chewing in prehistoric coastal peru: dental evidence. american journal of physical anthropology, 114 (3), 242-257. kelley, m. a., levesque, d.r., & weidl, e. (1991). contrasting patterns of dental disease in five early northern chilean groups. in: advances in dental anthropology. m. a. kelley & c. s. larsen (eds.). new york: wiley-liss. konig, k. g. (2000). diet and oral health. international dental journal, 50(3), 162-174. larjava, h. (2012). oral wound healing: cell biology and clinical management. wiley-blackwell: west sussex. larsen, c.s. (1995). biological changes in human populations with agriculture. annual review of anthropology, 24, 185-213. littleton, j. & frolich b. (1993). fish-eaters and farmers: dental pathology in the arabian gulf. american journal of physical anthropology, 92, 427-447. luby, e.m. (2004). shell mounds and mortuary behavior in the san francisco bay area. north american archaeologist, 25(1), 1-33. lukacs, j.r. (1995). the ‘caries correction factor’: a new method of calibrating dental caries rates to compensate for antemortem loss of teeth. international journal of osteoarchaeology, 5, 15131 dental anthropology 2022 │ volume 35│ issue 01 156. lukacs, j. r. (2007). dental trauma and antemortem tooth loss in prehistoric canary islanders: prevalence and contributing factors. international journal of osteoarchaeology, 17(2), 157-173. moynihan, p. (2005). the interrelationship between diet and oral health. proceedings of the nutrition society, 64, 571-580. meller, c., urzua, i., moncada, g. & von ohle, c. (2009). prevalence of oral pathologic findings in an ancient pre-columbian archaeologic site in the atacama desert. oral diseases, 15, 287294. nelson, g.c., lukacs, j.r., & yule, p. (1999). dates, caries, and early tooth loss during the iron age of oman. american journal of physical anthropology, 108(3), 333-343. oliveira, r.n., melani, r.f.n., antunes, j.l.f., freitas, e.r., & galvão, l.c.c. (2000). postmortem tooth loss in human identification processes. the journal of forensic odonto-somatology, 18 (2), 32-36. pilloud, m. a. & fancher, j.p. (2019). outlining a definition of oral health within the study of human skeletal remains. dental anthropology, 32(2), 3-11. powell, m. l. (1985). the analysis of dental wear and caries for dietary reconstruction. in r. i. gilbert & j. h. mielke (eds.) the analysis of prehistoric diets (pp. 307-338). orlando: academic press. scott, g.r. & turner ii, c.g. (1988). dental anthropology. annual review of anthropology, 17, 99126. scott, e.c. (1979). dental wear scoring technique. american journal of physical anthropology, 51(2), 213-217. seo, b.m., miura, m., gronthos, s., bartold, p.m., batouli, s., brahim, j., young, m., gehron robey, p., wang, c., & shi, s. (2004). investigation of multipotent postnatal stem cells from human periodontal ligament. lancet, 364, 149-55. shiroma, c.y., terrado-naguinlin, p.m., & zuerlein, c.l. (2019). healing alveolar sockets in skeletonized remains: a report on cases from one month to twelve months post-extraction. forensic science international, 301, e38-e43. smith, b.g., & knight, j.k. (1984). an index for measuring the wear of teeth. british dental journal, 156(12), 435-8. tibbett, m. & carter, d.o. (2008). soil analysis in forensic taphonomy: chemical and biological effects of buried human remains. crc press: boca raton. tuller, h. & ðurić, m. (2006). keeping the pieces together: comparison of mass grave excavation methodology. forensic science international, 156, 192-200. tuller, h., durio, m., & rakočević, z. (2004). factors affecting postmortem tooth loss. journal of forensic sciences, 49(6), 1313-1318. ajayi et al. 2010.4 57 the availability of information about the size of individual tooth types and groups of teeth in the maxillary and mandibular arches is of importance in clinical orthodontics as it facilitates orthodontic diagnosis and treatment planning (richardson and malhotra, 1975). the desire to achieve stable occlusion during and after orthodontic treatment also necessitates the need for knowledge about tooth crown dimensions and ratios since without coordination between the sizes of the upper and lower teeth, it would not be possible to have correct intercuspation of the teeth, overjet, overbite and optimal occlusion (andrews, 1972; ballard, 1944; mclaughlin, 2001; smith et al., 2000). an early study on the mesiodistal widths of teeth was conducted by black (1902) who also provided data on mean tooth dimensions. presently, a lot of data are available in the literature for tooth dimensions of different populations and some variations in tooth sizes between gender and among different racial and ethnic groups have been reported (richardson and malhotra, 1975; moyers et al., 1976; moorrees et al., 1957; santoro et al., 2000; bishara et al., 1989; merz et al., 1991; singh and goyal, 2006). there is dearth of information on mesiodistal tooth size in nigerians and the few studies available were conducted in the southwestern region of the country (mack, 1981; otuyemi and noar, 1996; adeyemi and isiekwe, 2003). presently, there are no data on mesiodistal crown dimensions of the permanent dentition of nigerians in the southern and eastern regions of nigeria. it is therefore desirable to determine standards for mesiodistal tooth size for the nigerian population who invariably constitute the mesiodistal crown dimensions of the permanent dentition in a nigerian population emmanuel o. ajayi1, yetunde o. ajayi2, helen o. oboro3, and nneka m. chukwumah4 1orthodontic unit, department of preventive dentistry, college of medical sciences, university of benin, benin city, nigeria 2department of restorative dentistry, college of medicine, university of lagos, nigeria 3department of restorative dentistry, university of benin teaching hospital, benin city, nigeria 4department of preventive dentistry, university of benin teaching hospital, benin city, nigeria correspondence: emmanuel o. ajayi, p.o. box 7272, surulere, lagos, nigeria e-mail: buskyet@yahoo.com abstract mesiodistal crown dimensions of the permanent dentition were assessed in a nigerian population. the study sample consisted of 54 dental casts of nigerian subjects (33 males; 21 females) with a mean age of 26.6 (sd = 2.1) years. the subjects had their permanent teeth present and fully erupted from first molar to first molar, no interproximal caries or restorations and no abnormal tooth sizes or shapes. descriptive statistics are provided. sex differences in the means and comparisons with the means from other population were evaluated using t-tests. results revealed no statistically significant difference in mesiodistal crown dimensions between the sexes and no left to right side tooth size discrepancy in the sample. the study provides normative data on the mesiodistal crown dimensions of nigerian subjects. compared to african americans, crown dimensions tended to be smaller in these nigerians, especially in males. dental anthropology 2010;23(2):57-60. largest congregation of black people in the world. the purposes of this study were to establish normative data on the mesiodistal crown dimensions of the permanent dentition in a nigerian population, identify any gender differences, and compare their mean mesiodistal crown dimensions to other racial groups. materials and methods the sample for this study consisted of 54 nigerian students made up of 33 males (61%) and 21 females (39%) with a mean age of 26.6 years (sd = 2.1) selected among the 74 final year students at the school of dentistry of university of benin, benin city. the selection criteria included being a nigerian, permanent teeth present and fully erupted, particularly from the first molar to first molar, no missing teeth, no teeth with abnormal sizes or shapes, no interproximal caries or excess tooth material as a result of restorations, and no presence of dental attrition. the 54 subjects who met the selection criteria were born of nigerian parents and they predominantly belong to the major ethnic groups of the southern and southeastern regions of nigeria. impressions of the upper and lower arches were taken for each subject in alginate and poured immediately in dental stone to prevent dimensional changes. the dental casts were measured with a digital vernier caliper. the 58 data analysis was carried out with the statistical package for social sciences software version 16 (spss, chicago, illinois). descriptive statistics including means, standard deviation, range, and coefficient of variation were calculated for each tooth dimension. the possibility of significant statistical differences in the tooth dimensions between the left and right side of the arch in the maxilla and mandible was evaluated using paired t-tests. existence of a statistical difference between the sexes or between this sample and another racial group was evaluated with unpaired t-tests. statistical significance was regarded when p < 0.05. results there was no statistical difference in the tooth dimensions between left and right sides of the arches (p > 0.05). the means, range, standard deviation, and statistical comparison of crown size dimensions in male and females are shown in table 1. there was no statistically significant difference for mesiodistal crown dimensions between males and females (p > 0.05), so statistics for the combined data are provided in table 2. the sex-specific mean mesiodistal measurements obtained for these nigerian subjects were compared with the mean values of african americans. table 3 shows that there were similarities in tooth sizes of the maxillary lateral incisor and canine and mandibular central incisor, lateral incisor and canine between nigerian and african american males while the other 7 dimensions were statistically different (p < 0.05). there was a greater similarity in maxillary tooth sizes of nigerian and african american females as shown in table 4, except the table 1. comparison of mean, range and standard deviation for mesiodistal crown dimension of permanent dentition of nigerian males and females males (n = 33) females (n = 21) tooth† mean range sd mean range sd p-value maxillary i1 8.80 7.38 10.48 0.70 8.81 7.10 9.98 0.67 ns‡ i2 7.21 5.66 8.46 0.58 7.16 5.64 8.18 0.55 ns c 8.07 7.18 9.12 0.43 7.85 7.05 9.10 0.51 ns p1 7.51 6.92 8.38 0.40 7.43 6.68 8.08 0.35 ns p2 7.01 6.04 8.12 0.46 7.13 6.10 8.18 0.52 ns m1 10.55 9.60 12.1 0.61 10.37 9.60 10.92 0.36 ns mandibular i1 5.58 4.62 6.37 0.38 5.62 4.70 6.18 0.35 ns i2 6.19 5.18 6.98 0.42 6.08 5.18 6.66 0.37 ns c 7.24 6.15 8.24 0.45 7.04 6.00 7.66 0.43 ns p1 7.57 6.82 8.30 0.43 7.43 7.06 8.30 0.33 ns p2 7.54 6.74 8.32 0.39 7.39 6.62 8.10 0.33 ns m1 11.24 10.36 12.1 0.32 11.13 10.68 11.80 0.26 ns †i1 central incisor, l2 lateral incisor, c canine, p1 first premolar, p2 second premolar, m1 first molar ‡ns, not significant; *significant difference at p < 0.05 table 2. descriptive statistics for mesiodistal crown dimension of permanent dentition of nigerian sample tooth mean range sd cv maxillary i1 8.80 7.10 10.48 0.68 7.75 i2 7.19 5.64 8.46 0.56 7.85 c 7.99 7.05 9.12 0.47 5.92 p1 7.48 6.68 8.38 0.38 5.08 p2 7.06 6.04 8.18 0.48 6.79 m1 10.48 9.60 12.1 0.53 5.05 mandibular i1 5.60 4.62 6.37 0.36 6.51 i2 6.15 5.18 6.98 0.40 6.52 c 7.16 6.00 8.24 0.45 6.29 p1 7.52 6.82 8.30 0.40 5.30 p2 7.48 6.62 8.32 0.37 5.00 m1 11.20 10.36 12.10 0.30 3.00 maximum mesiodistal widths of the incisors, canines, premolars, and first molars were measured. the caliper was placed parallel to the occlusal plane of each tooth with its sharp points at the greatest distances between the contact points on the proximal surface of each tooth and measurement taken and rounded to the nearest 0.1 mm. each tooth was measured twice by a single investigator and intra-examiner precision was set at 0.2 mm. differences greater than this limit caused a new set of measurements to be taken, and the nearest two measurements were averaged. e.o. ajayi et al. 59 maxillary first molar that was highly significantly larger in african american females (p < 0.001). the mandibular central incisor, second premolar, and first molar also were statistically different (p < 0.05) between the two groups. discussion the university students evaluated in this study provide a suitable sample of nigerian subjects who belong to the predominant ethnic groups in the southern and southeastern regions of nigeria where there were no normative data on the mesiodistal crown dimensions of the permanent dentition. there was no significant gender difference in the mesiodistal crown dimensions of permanent teeth in this sample of nigerians. mean values of the males were, however, slightly larger than females in both the maxillary and mandibular arches, and this observation was consistent with findings in african american (richardson and malhotra, 1975), dominican american (santoro et al., 2000), and indian populations (singh and goyal, 2006). in the maxilla, mean width of the central incisor was larger than lateral incisor and, similarly, mean width of the first premolar was larger than the second premolar, which was consistent with findings in an earlier nigerian study (adeyemi and isiekwe, 2003) and in other populations (richardson and malhotra, 1975; santoro et al., 2000; singh and goyal, 2006; uysal and sari, 2005). in the mandibular arch, the mean width of the central incisor was smaller than the lateral incisor while mean width of the first premolar was also smaller than the second premolar as reported elsewhere (richardson and malhotra, 1975; uysal and sari, 2005). the maxillary and mandibular first molar show least variability in mesiodistal tooth size in this sample. the variability of central and lateral incisors in the mandible are similar but show less variability than the maxillary incisors. the lateral incisor has the highest variability in the maxillary arch and should be of interest during clinical examination because of its location in the anterior maxillary segment and the possibility of crowding or spacing. the normative mesiodistal crown dimensions of the maxillary and mandibular permanent teeth for these nigerians were only similar to a few of those of african american sample reported by richard and malhotra (1975). for males, the sex-specific measurements for the nigerians compared to those of african americans revealed statistically significant differences in 7 of the 12 variables, with the african americans being larger. however, there was greater similarity between nigerian and african american females with the exception of the maxillary first molar, mandibular central incisor, second premolar, and first molar, which were significantly larger in the nigerian sample. these group differences in tooth sizes could be attributed to racial differences as previously observed in another comparative study of tooth sizes (bishara et al., 1989), but it is also important to note that the african american population is an admixture of multiple racial groups. this study re-emphasizes the importance of evaluation of mesiodistal tooth dimensions in different populations. a previous study involving nigerian children reported that the mesiodistal crown dimensions of the nigerian sample were significantly larger than a british caucasian sample (otuyemi and noar, 1996). also, some other studies have table 3. comparison of mean, range and standard deviation of nigerian males with african american males nigerian subjects african americans† tooth mean sd mean sd p-value maxillary i1 8.80 0.70 9.12 0.67 <0.05 i2 7.21 0.58 7.26 0.64 ns‡ c 8.07 0.43 8.19 0.53 ns p1 7.51 0.40 7.66 0.49 <0.05 p2 7.01 0.46 7.25 0.49 <0.01 m1 10.55 0.61 11.04 0.64 <0.001 mandibular i1 5.58 0.38 5.53 0.39 ns i2 6.19 0.42 6.13 0.44 ns c 7.24 0.45 7.37 0.57 ns p1 7.57 0.43 7.76 0.51 <0.05 p2 7.54 0.39 7.85 0.55 <0.001 m1 11.24 0.32 11.76 0.72 <0.001 †from richardson and malhotra (1975). ‡ns, not significant table 4. comparison of mean, range and standard deviation of nigerian females with african american females nigerian adults african americans† tooth mean sd mean sd p-value maxillary i1 8.81 0.67 8.72 0.58 ns‡ i2 7.16 0.55 7.08 0.56 ns c 7.85 0.51 7.74 0.38 ns p1 7.43 0.35 7.37 0.43 ns p2 7.13 0.52 6.94 0.39 ns m1 10.37 0.36 11.04 0.64 <0.001 mandibular i1 5.58 0.38 5.38 0.39 <0.01 i2 6.08 0.37 5.99 0.46 ns c 7.04 0.43 6.86 0.42 ns p1 7.43 0.33 7.41 0.50 ns p2 7.54 0.39 7.61 0.50 <0.01 m1 11.13 0.26 11.28 0.62 <0.05 †from richardson and malhotra (1975). ‡ns, not significant mesiodistal crown dimensions of nigerians 60 shown that american blacks have significantly larger tooth crowns and arch dimensions than american whites (richardson and malhotra, 1975; merz et al., 1991; burris and harris, 2000). it is important that ethnic and individual variations and treatment needs be taken into consideration in the evaluation of patients, diagnosis, and treatment planning in order to achieve desired treatment objectives and optimal occlusion. conclusion the study provided normative data on the mesiodistal crown dimensions of nigerian subjects. the males and females exhibited similar patterns of tooth size even though the mean values of the tooth size of the males were slightly larger. the mean tooth sizes of nigerian and african american population were only comparable for a few teeth in the maxilla and mandible. literature cited adeyemi ta, isiekwe mc. 2003. mesio-distal crown dimensions of permanent teeth in a nigerian population. afr j med med sci 32:23-25. andrews lf. 1972. the six keys to normal occlusion. am j orthod 62:296-309. ballard ml. 1944. asymmetry in tooth size: a factor in the etiology, diagnosis and treatment of malocclusion. angle orthod 14:67-71. bishara se, jakobsen jr, abdallah em, garcia af. 1989. comparisons of mesiodistal and buccolingual crown dimensions of the permanent teeth in three populations from egypt, mexico and the united states. am j orthod dentofacial orthop 96: 416-422. black gv. 1902. descriptive anatomy of human teeth, 4th edition. philadelphia: s s white. burris bg, harris ef. 2000. maxillary arch size and shape in american blacks and whites. angle orthod 70:297302. mack pj. 1981. maxillary arch and central incisor dimensions in a nigerian and british population sample. j dent 9:67-70. mclaughlin rp, bennett jc, trevisi hj. 2001. systemised orthodontic treatment mechanics. st louis: mosby, p 285. merz ml, isaacson rj, germane n, rubenstein lk. 1991. tooth diameters and arch perimeters in a black and a white population. am j orthod dentofacial orthop 100:53-58. moyers re, van der linden fpgm, riolo ml, mcnamara ja jr. 1976. standards of human occlusal cevelopment. monograph 5. ann arbor, mi: center for human growth and development, university of michigan. moorrees cfa, thomsen so, jensen e, yen pk. 1957. mesiodistal crown diameter of the deciduous and permanent teeth in individuals. j dent res 36:39-47. otuyemi od, noar jh. 1996. a comparison of crown size dimensions of the permanent teeth in a nigerian and a british population. eur j orthod 18:623-628. richardson re, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 68:157-164. santoro m, ayoub me, pardi va, cangialosi tj. 2000. mesiodistal crown dimensions and tooth size discrepancy of the permanent dentition of dominican americans. angle orthod 70:303-307. singh sp, goyal a. 2006. a mesiodistal crown dimensions of the permanent dentition in north indian children. j indian soc pedod prev dent 24:192-196. smith ss, buschang ph, watanabe e. 2000. interarch tooth size relationships of 3 populations: ‘does bolton’s analysis apply? am j orthod dentofacial orthop 117:169-174. uysal t, sari z. 2005. intermaxillary tooth size discrepancy and mesiodistal crown dimensions for a turkish population. am j orthod dentofacial orthop 128:226230. e.o. ajayi et al. the 15th international symposium on dental morphology will be held from 24-27 august, 2011 at northumbria university in newcastle upon tyne, united kingdom, sponsored by the newcastle university school of dental sciences. this symposium will bring together scholars from around the world to present research in all aspects of dental morphology. the range of presentations will be broad and include topics such as dental anthropology, dental evolution, dental function, growth and development, dental tissues, and the genetics and clinical aspects of dental morphology. for more information or to be added to our mailing list, please contact dr wendy dirks (wendy.dirks@ncl.ac.uk ). 35 dental anthropology 2021 │ volume 34│ issue 01 the meuse river basin of central belgium extends along a semi-continuous karstic uplift featuring numerous cliff walls, rock formations and at least 3,000 caverns. more than 250 of these caves preserve the remains of prehistoric humans. although these caves have been known for centuries, formal exploration of the sites commenced in the winter of 1829-1830 and has continued to the present (polet, 2011). close to 200 of these funerary sites have been radiocarbon dated to the late neolithic period (toussaint et al., 2001). many of these are collective burials and contain five to 15 individuals (polet, 2011), however, some are larger, such as the caves of bois madame and sclaigneaux (dumbruch, 2003; de paep & polet, 2007). only eight percent of these funerary sites contain between 55 and 60 individuals (polet, 2011). hundreds of skeletal fragments and dental elements have been investigated from hastière caverne m (hastière m), hastière trou garçon c (trou garçon), sclaigneaux, bois madame and maurenne caverne de la cave (maurenne) (figure 1), and adults of both sexes and children are represented, suggesting familial, kin or descent groups used the caves for burial. these five cave deposits are all radiocarbon dated to the late neolithic (table 1). however, maurenne is associated with three dates from the terminus of the late neolithic (4,160 ± 45; 3,950 ± 70; 3,830 ± 90 years bp), and one date, 4,635 ± 45 years bp, from the middle neolithpermanent molar trait expression in the late neolithic cave burials of the meuse basin, belgium frank l’engle williams 1* and rebecca l. george 2 1 georgia state university 2 university of nevada, reno abstract at least 250 cave burials along the meuse river basin of belgium yield prehistoric remains, and most date from the late neolithic period. several of these collective burials have been radiocarbon dated, including the early/late neolithic deposits of hastière caverne m and hastière trou garçon c and the final/late neolithic caves of sclaigneaux and bois madame. an additional cave burial, maurenne caverne de la cave, has been radiocarbon dated to the middle neolithic and final/late neolithic periods, circa 4,635 to 3,830 years bp, which encompasses the entire range of dates for the other collective burials. individuals (n = 127) are represented by fragmentary gnathic remains with in situ dental elements. although the remains have been studied in detail, researchers have yet to compare dental morphology across cave sites. arizona state university dental anthropology system (asudas) scores of permanent molar morphology are employed to examine whether differences within and between the cave burials exist, and whether chronology and geography can account for the variation in traits. affirming our expectations, the final/late neolithic cave of sclaigneaux, the most geographically distant cave burial, and secondarily hastière caverne m, possibly the earliest site, emerge as the most distinctive. the final/late neolithic sites of sclaigneaux and bois madame exhibit the greatest variability of trait expression. this research contributes to the understanding of the relatedness of early farming communities, and these findings bear on the mobility and continuity of human groups in the meuse basin of belgium during the terminus of the neolithic before the onset of the bronze age in northern europe. *correspondence to: frank l’engle williams department of anthropology georgia state university p.o. box 3998 atlanta, ga, 30302-3998 united states frankwilliams@gsu.edu keywords: hastière caverne m, hastière trou garçon c, sclaigneaux, bois madame, maurenne caverne de la cave mailto:frankwilliams@gsu.edu 36 dental anthropology 2021 │ volume 34│ issue 01 figure 1. map of belgium showing the location of five late neolithic collective burials along the meuse river system. table 1. radiocarbon dates associated with five neolithic collective burials of belgium, arranged by site and by distance from hastière rockshelter; dating was conducted using accelerated mass spectrometry (ams) at oxford university, uk (oxa) and the university of groningen (gra), and conventional methods at the university of louvain, belgium (lv). a early/late neolithic; b middle neolithic; c final/late neolithic collective burial sample number dates in years bp reference hastière m ams oxa-6558 4,345 ± 60a bronk-ramsey et al. (2002) trou garçon ams oxa-6853 4,220 ± 45a bronk-ramsey et al. (2002) maurenne ams oxa-9025 4,635 ± 45b bronk-ramsey et al. (2002) maurenne ams oxa-9026 4,160 ± 45c bronk-ramsey et al. (2002) maurenne lv-1483 3,950 ± 70c toussaint (2007) maurenne lv-1482 3,830 ± 90c toussaint (2007) bois madame ams oxa 10831 4,075 ± 38c dumbruch (2003) bois madame ams oxa 10830 3,910 ± 40c dumbruch (2003) sclaigneaux gra-32975 4,155 ± 35c de paepe & polet (2007) 37 dental anthropology 2021 │ volume 34│ issue 01 ic, implying its use for more than 800 years (vanderveken, 1997; bronk-ramsey et al., 2002; toussaint, 2007). the maurenne burial is adjacent to hastière rockshelter formation (see figure 1). two other collective burials at this site include hastière m and trou garçon. hastière m is one of the oldest late neolithic cave sites and dates to 4,345 ± 60 years bp, followed by trou garçon, which has yielded a date of 4,220 ± 45 years bp (bronkramsey et al., 2002; toussaint, 2007). these two can be described as early/late neolithic. two large, well-studied final/late neolithic cave burials are sclaigneaux and bois madame. sclaigneaux is associated with a single radiocarbon date of 4,155 ± 35 years bp (de paepe, 2007; de paepe & polet 2007). at bois madame in the burnot valley, two dates have been obtained. both of these derive from the boundary of the fourth millennium prior to the bronze age, 4,075 ± 38 years bp and 3,910 ± 40 years bp, suggesting the collective burial of bois madame may have been utilized for more than 150 years (bronk-ramsey et al., 2002; dumbruch, 2003, 2007). funerary context given the scarcity of habitation sites, these prehistoric peoples are primarily known from their remains in funerary caves and rockshelters. a range of burial practices has been inferred, including cremation, burial, a simple deposition of individuals on cave floors and cu-marks with flint implements. comingled remains comprise a majority of the funerary deposits (toussaint et al., 2001; toussaint, 2007; polet, 2011). at some caves, such as bois madame, the bones are found in a haphazard order as if the individuals were left unburied and later disturbed by human or non-anthropogenic agents (dumbruch, 2003). the mixture of individuals within these collective burials could have arisen from bioturbation. however, the deliberate movement, occasional regrouping and comingling of bodies is more likely to be the result of burial rites, reburial and/or adding additional individuals (toussaint et al., 2001; toussaint, 2007). comparing individuals across cave burials although several well-preserved late neolithic crania are present, most individuals are represented by fragmentary gnathic remains with associated molars in situ, permitting an investigation of variation within and between sites in nonmetric dental trait expression using the arizona state university dental anthropology system (asudas) (turner et al., 1991; scott and irish, 2017). prior studies of the inhabitants of these late neolithic caves have found a lack of differentiation in diet (garcia martín, 1999; semal et al., 1999), internment behavior (vanderveken, 1997; toussaint et al., 2001, 2003) and stature was estimated to be largely unimodal (orban et al., 2000). however, chronological distinctions are apparent from radiocarbon dating. on the basis of chronology, we expect the early/late neolithic sites to be more similar to each other in dental morphological expression than to the final/ late cave burials, and vice versa. the three final/ late neolithic dates from maurenne suggest this collective burial is more likely to resemble later sites than earlier ones. it is also possible that differences in dental morphology will be patterned with respect to geography. based on distance, individuals from hastière rockshelter (hastière m and trou garçon) and maurenne should be more similar to one another, and secondarily to bois madame, whereas sclaigneaux should be the most distinctive (see figure 1). materials and methods a total of 127 individuals from the five caves were examined (vanderveken, 1997; toussaint et al., table 2. neolithic samples by cave, element, and number of individuals. neolithic cave site maxillae mandibles total hastière m 10 10 20 trou garçon 6 1 7 maurenne 9 21 30 bois madame 13 15 28 sclaigneaux 12 30 42 total 50 77 127 38 dental anthropology 2021 │ volume 34│ issue 01 2001; dumbruch, 2003; de paep, 2007; toussaint, 2007; williams and polet, 2017; table 2). gnathic fragments were chosen on the basis of completeness and only relatively unworn crowns were examined. no isolated teeth were included to avoid errors in attribution. given the lack of anterior teeth preserved in situ, and the inconsistent preservation of premolars, only molars were observed. preference was given to young adults and subadults with relatively unworn cusps of permanent molars to increase the likelihood of accurate scoring, and included smith (1984) wear stages 1 to 4. individuals who exhibited substantial attrition, exceeding stage 4 (smith, 1984), were excluded from the analysis (turner et al., 1991; scott and irish, 2017). dental cast preparation dental casts were created from dental impressions of the original neolithic material housed at the royal belgian institute of natural sciences in brussels. to create the dental molds, the dentition was cleaned and a thin layer of dental molding material, polyvinylsiloxane (president jet plus regular body, coltène-whaledent) was applied to the occlusal surface of the molars and allowed to air dry. dental casts were created at georgia state university by pouring centrifuged epoxy resin and hardener (buehler) onto the dental impressions, which were placed into putty crucibles—stabilized with hardener (buehler)—to catch the excess mixture. the casts dried for 24 hours before extraction. analysis dental morphology has been shown to be highly heritable (turner et al., 1991; scott and turner, 1997; irish, 2006; hanihara, 2008; scott and irish, 2017; scott et al., 2018). dental casts, supplemented with photographic images, were scored by a single observer (rlg) to avoid issues of interobserver error (turner and scott, 1997; hardin and legge, 2013). previously conducted intraobserver error analyses on 34 dental morphological traits found trait agreement at levels of 0.621 or above (mchugh, 2012). since single-sided gnathic fragments were available for the great majority of the individuals, dental antimeres could not be examined to identify the maximum expression of any trait. it is possible that some of the maxillary and mandibular fragments belonged to the same individuals. however, given the preservation of the remains, pairing these elements was not possible. if some elements are indeed associated, then the total sample size of 127 would be smaller. since 77 mandibular and 50 maxillary fragments are included, a potential minimum number of individuals (mni) is 77 (table 2). these associations are likely irrelevant in the current study as maxillary and mandibular molar traits are discussed separately another potential problem from the lack of matching elements might have arisen from inadvertently scoring antimeres from the same individual. however, this is unlikely for several reasons. first, only in situ molars rather than isolated elements were scored. second, the range of dental attrition and dental ages suggests each gnathic fragment can be considered unique. therefore, each fragment was treated as an individual (hardin and legge, 2013) as shown in table 2, and the dental morphological traits were discussed independently. score frequencies for each trait with respect to each cave site were calculated. statistical analyses were not attempted due to the small and idiosyncratic sample sizes. results all scores ascribed to individuals are presented in the context of the asudas. maxillary molars metacone for m1, individuals from hastière m and trou garçon often exhibit a metacone with a score of 4 (see table 3). fewer individuals have a larger metacone with a score of 5. in contrast, individuals from maurenne and bois madame frequently present a metacone with a score of 5 and have a lower frequency of individuals with a score of 4. sclaigneaux shows an equal prevalence of individuals with metacone scores of 4 and 5. for the second molar (m2), the dominant pattern across sites is a score of 3 or 4, though there is some variation in expression (table 3). for instance, hastière m and trou garçon are nearly divided equally between these two scores, whereas the final/late neolithic burials present a greater tendency for a metacone with a score of 4. individuals from bois madame show a greater range of expression in their metacone scores as they range from 2 to 5. although the sample size for m3 is limited, the individual from hastière m has a large metacone with a score of 5, whereas individuals from both maurenne and bois madame exhibit a smaller cusp and have scores of 3. the other two sites are intermediate and have scores of 4 for the m3 metacone (table 3). 39 dental anthropology 2021 │ volume 34│ issue 01 table 3. frequencies of maxillary traits. frequency of score site n trait & tooth 0 1 2 3 4 5 6 7 hastière m 8 metacone (m1) 0.875 0.125 trou garçon 5 0.800 0.200 sclaigneaux 10 0.500 0.500 maurenne 8 0.250 0.750 bois madame 11 0.273 0.727 hastière m 5 metacone (m2) 0.600 0.400 trou garçon 4 0.500 0.500 sclaigneaux 6 0.167 0.833 maurenne 3 0.333 0.667 bois madame 8 0.125 0.125 0.375 0.375 hastière m 1 metacone (m3) 1.000 trou garçon 2 0.500 0.500 sclaigneaux 3 0.333 0.667 maurenne 1 1.000 bois madame 2 1.000 hastière m 7 hypocone (m1) 0.429 0.571 trou garçon 4 0.500 0.500 sclaigneaux 10 0.400 0.600 maurenne 8 0.125 0.875 bois madame 11 0.273 0.364 0.364 hastière m 6 hypocone (m2) 0.167 0.667 0.167 trou garçon 2 1.000 sclaigneaux 4 0.500 0.500 maurenne 3 0.333 0.667 bois madame 8 0.125 0.750 0.125 hastière m 1 hypocone (m3) 1.000 trou garçon 1 1.000 sclaigneaux 3 0.333 0.333 0.333 maurenne 4 1.000 bois madame 2 0.500 0.500 hastière m 5 metaconule (m1) 0.800 0.200 trou garçon 3 0.667 0.333 sclaigneaux 8 1.000 maurenne 6 0.833 0.167 bois madame 9 0.667 0.333 hastière m 8 metaconule (m2) 0.500 0.250 0.125 0.125 trou garçon 4 0.500 0.250 0.250 sclaigneaux 4 1.000 maurenne 2 0.500 0.500 bois madame 7 0.714 0.286 hastière m 1 metaconule (m3) 1.000 trou garçon 2 0.500 0.500 sclaigneaux 2 1.000 maurenne 1 1.000 bois madame 2 0.500 0.500 hastière m 3 carabelli's trait (m1) 0.333 0.667 trou garçon 2 0.500 0.500 sclaigneaux 3 0.333 0.333 0.333 maurenne 2 1.000 bois madame 5 0.200 0.200 0.200 0.200 0.200 hastière m 3 carabelli's trait (m2) 1.000 trou garçon 1 1.000 sclaigneaux 2 0.500 0.500 maurenne 3 1.000 bois madame 2 0.500 0.500 hastière m 4 parastyle (m1) 1.000 trou garçon 3 1.000 sclaigneaux 3 0.667 0.333 maurenne 2 1.000 bois madame 8 1.000 hastière m 5 parastyle (m2) 1.000 trou garçon 3 0.667 0.333 sclaigneaux 4 0.750 0.250 bois madame 7 1.000 40 dental anthropology 2021 │ volume 34│ issue 01 hypocone the m1 hypocone is primarily scored as a 4 or 5 nearly evenly across three of the sites (see table 3). most individuals from maurenne, though, are scored as 5 and more than a quarter of the m1 samples from bois madame (27.3%) exhibit a smaller hypocone and are characterized by scores of 3. for m2, the hypocone tends to be expressed most strongly at maurenne and sclaigneaux as most individuals at these sites have scores of 4. for bois madame and hastière m, a smaller hypocone with a score of 3 is the most frequent expression, with considerable variation (see able 3). the m3 hypocone is variably expressed at sclaigneaux and bois madame. in comparison, the m3 hypocone is most frequently larger at trou garçon and maurenne with scores of 4 (see table 3). metaconule (cusp 5) the metaconule is absent at sclaigneaux across the molars (see table 3). this is not the case at the other sites with the exception of m3 in which individuals from hastière m and maurenne also lack cusp 5. for m1, three individuals from bois madame present small metaconules with a score of 2. the early/late neolithic cave burials of hastière m and trou garçon both exhibit substantial variation in the expression of the metaconule across the molars (see table 3). variation at the early/late neolithic sites is particularly marked for the m2 at hastière m where the expression of cusp 5 ranges from absent in half of the individuals to moderately expressed with scores of 1-3 in the other half. trou garçon is mostly associated with scores of 1 and 2. maurenne and bois madame are similar in their low to absent expression of the metaconule on m2 and m3 (table 3). in contrast, a prominent metaconule is expressed on the m3 of hastière m 29, presenting a score of 5 (figure 2). carabelli’s trait carabelli’s trait is relatively well represented across these neolithic sites on m1 and m2 but is absent entirely on m3 (see table 3). however, there is considerable variation within and between burials (figures 3 and 4). for m1, bois madame exhibits the strongest expression of this trait, with one individual having a prominent carabelli’s cusp with a score of 7. bois madame present the greatest degree of variation, with expressions ranging from 25. one individual from sclaigneaux has a large carabelli’s trait with a score of 5 and another is even larger with a score of 6 (figure 4). in comparison, this trait on m1 is expressed as a 1 or absent altogether at the early/late neolithic sites of hastière m and trou garçon (see table 3). for m2, hastière m and trou garçon c lack expressions of carabelli’s trait while the final/late sites of sclaigneaux and bois madame show substantial variation ranging from scores 1-3 (see table 3). maurenne resembles the hastière m and trou garçon, in lacking evidence of a carabelli’s trait on m2 (see table 3). parastyle as at other locations worldwide (scott et al. 2018), the expression of a parastyle is rarely observed in these neolithic collective burials and is completely absent on m3 (see table 3). however, a large m1 parastyle is scored as a 3 on sclaigneaux 119. a smaller m2 parastyle is scored as a 2 on sclaigneaux 99. in addition, a limited expression of a parastyle is noted for one m2 from trou garçon (i.g. 3873) characterized as a buccal pit (score of 1). mandibular molars anterior fovea the anterior fovea on m1 is most frequently expressed as a score of 1 across the cave burials when it is present (table 4; figure 5). there is one individual, maurenne 92, who presents a larger anterior fovea with a score of 3. groove pattern the groove pattern for m1 is primarily the y pattern, with the exception of one individual from hastière m and another from sclaigneaux that exhibit an x pattern. the near ubiquity of the y pattern, particularly at the final/late neolithic cave burials, is further evidenced by the relatively large number of individuals with this configuration. this includes all of the maurenne (n = 12) and bois madame (n = 8) assemblages, and nine out of 10 individuals from sclaigneaux (see table 4). the groove patterns for m2 and m3 are more variable (see table 4). for m2, the groove pattern for the early/late neolithic cave burial of trou garçon presents as an x. individuals from hastière m most often exhibit the plus groove pattern with some expression of the y pattern. at maurenne, all three groove pattern variants are evident (see table 4). for m3, hastière m 10 exhibits an x groove pattern, as do most individuals from maurenne. the final/late neolithic sites exhibit more variability in groove patterning for both m2 and m3 than is observed for these teeth in the earlier cave burials. all three configurations are visible at sclaigneaux, although the y pattern is the least 41 dental anthropology 2021 │ volume 34│ issue 01 figure 2. hastière trou garçon c 20z, a right m1 shows (a) a large metaconule or cusp 5 (asudas score = 2) and (b) a pit form of carabelli’s trait (asudas score = 1); scale bar = 1 cm. figure 3. bois madame, bm mx 11, a right maxillary fragment, demonstrates a large carabelli’s trait (asudas score = 7), identified by a white arrow on m1; scale bar = 1 cm. figure 4. sclaigneaux 119, a left m1, exhibits (a) a pronounced carabelli’s cusp (asudas score = 6), and (b) a large metacone (asudas score = 4); scale bar = 1 cm. figure 5. bois madame bm md 32, a left m1, shows (a) an anterior fovea (asudas score = 1) and (b) a protostylid (asudas score = 1), both of which are commonly found across cave sites; scale bar = 1 cm. 42 dental anthropology 2021 │ volume 34│ issue 01 table 4. frequencies of mandibular traits. frequency of score site n trait & tooth 0 1 2 3 4 5 6 x y + hastière m 2 anterior fovea (m1) 1.000 sclaigneaux 4 0.750 0.250 maurenne 8 0.625 0.250 0.125 bois madame 4 0.500 0.500 hastière m 1 groove pattern (m1) 1.000 sclaigneaux 10 0.100 0.900 maurenne 12 1.000 bois madame 8 1.000 hastière m 4 groove pattern (m2) 0.250 0.750 trou garçon 1 1.000 sclaigneaux 15 0.400 0.067 0.533 maurenne 7 0.143 0.143 0.714 bois madame 8 0.375 0.250 0.375 hastière m 1 groove pattern (m3) 1.000 sclaigneaux 5 0.200 0.600 0.200 maurenne 3 0.667 0.333 bois madame 2 0.500 0.500 hastière m 4 cusp number (m1) 0.750 0.250 sclaigneaux 11 0.091 0.727 0.182 maurenne 12 0.333 0.583 0.083 bois madame 9 0.778 0.222 hastière m 5 cusp number (m2) 0.600 0.400 trou garçon 1 1.000 sclaigneaux 12 0.750 0.250 maurenne 8 1.000 bois madame 7 0.714 0.286 hastière m 1 cusp number (m3) 1.000 sclaigneaux 7 0.429 0.429 0.143 maurenne 3 1.000 bois madame 2 0.500 0.500 hastière m 5 mid-trigonid crest (m2) 1.000 trou garçon 1 1.000 sclaigneaux 12 0.917 0.083 maurenne 7 0.857 0.143 bois madame 5 1.000 hastière m 1 mid-trigonid crest (m3) 1.000 sclaigneaux 9 0.889 0.111 maurenne 3 1.000 bois madame 1 1.000 hastière m 5 protostylid (m1) 0.400 0.600 trou garçon 1 1.000 sclaigneaux 10 1.000 maurenne 13 0.538 0.462 bois madame 7 0.143 0.857 hastière m 4 protostylid (m2) 0.500 0.500 trou garçon 1 1.000 sclaigneaux 9 0.222 0.778 maurenne 8 0.250 0.750 bois madame 5 0.400 0.600 hastière m 1 protostylid (m3) 1.000 sclaigneaux 7 0.429 0.571 maurenne 2 0.500 0.500 bois madame 1 1.000 hastière m 2 hypoconulid (m1) 0.500 0.400 sclaigneaux 11 0.091 0.091 0.182 0.091 0.091 0.455 maurenne 13 0.308 0.308 0.154 0.231 bois madame 9 0.333 0.222 0.444 hastière m 5 hypoconulid (m2) 0.600 0.200 0.200 trou garçon 1 1.000 sclaigneaux 13 0.769 0.154 0.077 maurenne 8 1.000 bois madame 7 0.714 0.143 0.143 hastière m 1 hypoconulid (m3) 1.000 sclaigneaux 7 0.429 0.286 0.143 0.143 maurenne 3 1.000 bois madame 2 0.500 0.500 hastière m 4 entoconulid (m1) 0.750 0.250 sclaigneaux 11 0.818 0.182 maurenne 12 0.917 0.083 bois madame 9 0.778 0.111 0.111 hastière m 1 entoconulid (m3) 1.000 sclaigneaux 7 0.857 0.143 maurenne 3 1.000 bois madame 2 1.000 43 dental anthropology 2021 │ volume 34│ issue 01 prevalent on m2 and the most frequent expression on m3 (see table 4). all three groove patterns are present at bois madame for m2 as they are at sclaigneaux and maurenne. however, only at sclaigneaux are the three groove patterns present on m3. cusp number only five or six cusps are observed on m1 at the early/late neolithic cave burial of hastière m and the final/late site of bois madame, whereas sclaigneaux and maurenne both present 4-6 cusps. however, the predominant number is five cusps across the cave burials (see table 4). this pattern differs for m2 in which four cusps is the most frequently observed. for the individuals from maurenne (n = 8) and the individual from trou garçon, this is the only pattern observed for m2. in comparison, there are some m2 from hastière m, sclaigneaux and bois madame that present five cusps (see table 4). for m3, there are primarily four cusps, with the exception of maurenne and sclaigneaux in which the expression of four and five cusps are equally represented (table 4). furthermore, at sclaigneaux, more variation is observed for m3 cusp number which includes the expression of four, five and six cusps. mid-trigonid crest the mid-trigonid crest is eliminated for m1 since no presence was recorded across sites for this molar. the mid-trigonid crest is also largely absent on m2 and m3 at these neolithic cave burials. one exception is at sclaigneaux where it is present, although rarely, on both m2 and m3. the only other site where a mid-trigonid crest is observable is at maurenne and only the m2 of maurenne 18 (see table 4). protostylid a buccal pit (score of 1) is common at these neolithic cave deposits and across the mandibular molar row (figure 5). at sclaigneaux, the buccal pit is found on all individuals examined (n = 10). similarly, a buccal pit is more often present than absent on m1 at hastière m and bois madame. in contrast, at maurenne a buccal pit on m1 is more often absent than present; this feature is also absent in the single individual from trou garçon (table 4). on m2, a buccal pit is visible at all sites and is more often expressed than not, particularly at sclaigneaux and maurenne (see table 4). one exception is trou garçon 3, where a protostylid is scored as a 3. any variation of the protostylid is less frequently exhibited on m3 than on the other molars. at sclaigneaux, it is expressed as a buccal pit across the molar row. a much stronger expression of a protostylid is evidenced on one individual, maurenne 15, where it is scored as a 6. hypoconulid (cusp 5) for m1, hastière m exhibits a moderate to large hypoconulid, expressed at scores of 3 and 4. sclaigneaux presents the greatest degree of variation in the expression of the hypoconulid, ranging across the full spectrum of scores from 0-5, although the majority of individuals from this site are skewed towards the higher end of the scoring spectrum. this variation is similar at bois madame and maurenne where the scores range from 0-5. however, most individuals from bois madame exhibit a larger hypoconulid with a correspondingly higher score and nearly a third of the individuals from maurenne lack a cusp 5 entirely (see table 4). for m2, the hypoconulid is more often absent than present across cave burials, and at maurenne and trou garçon it is absent altogether. when it is expressed, the final/late neolithic caves of sclaigneaux and bois madame both show greater variation and the presence of a larger cusp 5. for example, when the hypoconulid is expressed at hastière m, it ranges in score from 1-3. at the final/late neolithic sites of sclaigneaux and bois madame, a larger hypoconulid is evident, reflected in one individual from each site scoring a 4 and 5, respectively (see table 4). like m2, the variation in m3 is more variable than observed in m1, especially for the final/late neolithic cave burials. the hypoconulid is completely absent in the one individual from hastière m and the three individuals from maurenne. in contrast, at the final/late neolithic cave of sclaigneaux, the greatest extent of variation is observed, with scores ranging from a low of 1 to a high of 5. bois madame has similar variability of expression of the hypoconulid, with scores extending from 0-4. entoconulid (cusp 6) an entoconulid is expressed on m1 across the cave burials but at low frequencies. however, its expression varies. the most common expression of the entoconulid, or cusp 6, is a score of 2, as observed at hastière m, maurenne and bois mad44 dental anthropology 2021 │ volume 34│ issue 01 ame. sclaigneaux presents an entoconulid with a score of 1. at the other extreme is bois madame in which a larger entoconulid is scored as a 3. thus, the final/late neolithic caves of sclaigneaux and bois madame are distinct in the expression of cusp 6 as compared to the other sites. the entoconulid on m2 was eliminated from the results because it is not observed across the sites. for m3, the entoconulid is entirely absent with the exception of sclaigneaux. this final/late neolithic cave burial presents one individual (sclaigneaux 19) out of seven with an entoconulid on m3 that is scored as a 2. metaconulid (cusp 7) frequencies for the metaconulid (cusp 7) are excluded since only a single tooth fully expressed this trait in the available neolithic sample, the left m1 of boise madame bm md 13 (figure 6). discussion based on an earlier study of deciduous molar morphology (williams et al., 2018), it was predicted that the early/late neolithic cave burial of hastière m would be distinctive and should differ from the final/late sites of sclaigneaux and bois madame. although this prediction was confirmed for some traits, the deciduous molar morphology of hastière m is more distinctive compared to the permanent molars. the observation that deciduous molars are better at identifying relatedness (paul and stojanowski, 2017) may also apply to these neolithic cave burials. it was also anticipated that sclaigneaux— situated about 35 km from the hastière rockshelter—would be distinct if differences in morphology can be explained by geographic distance (figure 1). sclaigneaux does differ from the other cave burials in some respects, for example, showing the y groove pattern for m2. however, like the other final/late neolithic site of bois madame, sclaigneaux is quite variable in the expression of traits. these findings suggest variability is more pronounced in the final/late than the early/late neolithic. the final/late neolithic sites exhibit greater variation in the expression of traits, particularly the hypoconulid, protostylid, parastyle and carabelli’s trait across the molar row. however, the sample sizes are also substantially larger at the final/late neolithic sites. this is particularly true of sclaigneaux. it is unknown the extent to which the uneven sample sizes influenced the results. it was expected that the two early/late neolithic cave burials of hastière m and trou garçon should resemble one another as they are similar chronologically and geographically. yet there is no convincing evidence that they are similar. in fact, it appears that trou garçon resembles the final/late neolithic sites of bois madame and secondarily maurenne more than these individuals resemble hastière m. trou garçon has a greater number of whole crania available but is represented by a smaller number of individuals compared to the other sites (table 2). the limited sample size for trou garçon precludes definitive statements on its relationship to the other cave burials. however, trou garçon individuals are at times extreme in the expression of traits which separates this site from the others, such as a large protostylid on m2 in trou garçon 3. meanwhile, hastière m is an outlier in other ways, such as the pronounced metaconule on m3 in hastière m 29. the prediction that maurenne would resemble the final/late neolithic sites of sclaigneaux and bois madame more than hastière m was largely confirmed by the results. for this reason, it is more likely that the individuals buried at maurenne are primarily associated with the three final/late neolithic radiocarbon dates. the single middle neolithic date obtained from maurenne may be an exception. supporting this assertion is the observation of similarities between maurenne and bois madame. three of the dates for the former and the two dates for the latter overlap one another and the two burial chambers are about 10 km from one another suggesting, perhaps, closer contact existed between these two groups than between the earlier figure 6. left mandibular fragment of bm md 13, presents the only fully expressed metaconulid (cusp 7) observed (asudas score = 2), demarcated by the white arrow on m1; scale bar = 1 cm. 45 dental anthropology 2021 │ volume 34│ issue 01 and the more geographically distant individuals living close to sclaigneaux cave. there are also similarities between the caves, such as the large prevalence of a protostylid and carabelli’s trait, and the near absence of a metaconulid. there are most frequently five cusps on m1 but often four on m2 and m3. the lack of discrete differences in these belgian neolithic caves is supported by archaeological evidence that suggests common lifeways, an undifferentiated economy and phenotypic homogeneity. carbon and nitrogen isotopes imply similarities in diet across the late neolithic period in which terrestrial resources were relied upon more than aquatic ones (semal et al., 1999). the dental microwear of several late neolithic caves suggests similarities in diet which comprised a large amount of vegetable fiber (garcia-martín, 2000), but fish may have also been consumed (toussaint et al., 2001). stature regression formulae from available neolithic long bones and the first metatarsal indicate that most of the individuals were of short stature. it is also possible that the majority of the long bones come from a single sex (female) as the sample lacks a bimodal distribution of values typical of recent belgians of both sexes (orban et al., 2000). comparison with other prehistoric burials a number of studies have been conducted using dental morphology as a proxy for affinity at neolithic and other prehistoric sites. studies of kinship within and across burials and cemeteries rely on phenotypic similarity as a proxy for genetic relationships and rare traits are often utilized to identify familial relations (bentley, 1991; howell and kintigh, 1996; alt et al., 1997; jacobi, 1997; corruccini and shimada, 2002; stojanowski & schillaci, 2006; pilloud, 2009; lukacs & pal, 2013). familial, and possibly sibling relations among a triple burial at dolní věstonice from the upper paleolithic of the czech republic were evidenced by a sharing of groove pattern, number of cusps, accessory cusps and the presence of an entoconulid and parastyle for at least two of the three individual for each trait (alt et al., 1997). the neolithic cave burials of belgium probably do not represent individuals from the same family as noted at dolní věstonice. in fact, it appears that there is a greater degree of variation within the belgian meuse neolithic burials than between them. dental traits of early neolithic mediterranean sites the dental morphology of several burial sites in the mediterranean region have been explored. for example, at early neolithic çatalhöyük in turkey, the protostylid, carabelli’s cusp, groove pattern, the hypoconulid, entoconulid, hypocone and deflecting wrinkle are significantly different from expected (pilloud, 2009; pilloud and larsen, 2011). iberian and italian neolithic burials differ in carabelli’s trait and the protostylid among other dental traits (lópez-onaindia & subirà, 2017). the protostylid on m2 and m3, the hypoconulid of m1 and m2, and the entoconulid on m2 and to a lesser extent, groove pattern and cusp number on m2, are suggested to be the most informative in separating iberian from italian neolithic burials (lópezonaindia et al., 2018). the neolithic cave burials of belgium exhibit substantial variation in all of these traits, particularly the size of the hypocone and the expression of carabelli’s trait, and remarkable uniformity in the presence of a protostylid. dental morphology of late neolithic cave burials of eurasia numerous late neolithic collective burials exist across eurasia, such as the late neolithicchalcolithic collective tombs of catalonia in which natural crevices and recesses include adults of both sexes and all ages with few grave goods (lópezonaindia et al., 2018). however, the dental morphology of only a few late neolithic sites have been studied in detail. an important exception concerns those surrounding lake baikal, siberia where an increasingly greater percentage of carabelli’s trait occurs during the neolithic period (waters-rist et al., 2016). compared to the late neolithic collective burials of belgium, a lower expression of this trait is observed and only at bois madame and sclaigneaux is a large carabelli’s cusp evident (table 3). hastiére m and bois madame have higher frequencies of a y groove pattern on m2 (0.250) compared to those observed in late neolithic siberians (0.140) (waters-rist et al., 2016), although sclaigneaux has a much lower value of 0.067 (see table 4). for cusp number of m2, 71.4% of the siberian late neolithic peoples of lake baikal exhibit 5+ cusps whereas the late neolithic burials from belgium can be characterized as expressing fewer cusps on the second mandibular molar. in fact, mostly only four cusps are observed on m2. however, hastiére m, and to a lesser extent, bois madame and sclaigneaux, show some expression of five cusps on m2, ranging from 0.400 to 0.250 (see table 4). expression of a protostylid on m1 is present in half of late neolithic peoples of lake baikal, siberia (waters-rist et al., 2016), whereas for this temporal period in the meuse riv46 dental anthropology 2021 │ volume 34│ issue 01 er basin of belgium is it present more often than it is absent, and at sclaigneaux it is observed in 100% of individuals (n = 10) (table 4). more than a quarter of individuals (27%) of the late neolithic of siberia exhibit an entoconulid (cusp 6) on m1 (waters-rist et al., 2016). comparable frequencies for the collective burials of late neolithic belgium for this trait exist at hastiére m and to a lesser extent, bois madame (table 4). unlike their counterparts to the east who exhibit a low occurrence of a metaconulid (cusp 7) on m1 at 6.5% (waters-rist et al., 2016), at the late neolithic caves of belgium, it is nearly absent with the exception of bm md 13 from bois madame (figure 6). conclusions the five well-studied collective burials examined are somewhat discrete in terms of chronology based on radiocarbon dates. although only limited samples are available for each cave burial, it appears that our predictions were confirmed. hastière m is only partly distinct from the other cave deposits in the expression of traits, corroborating an analysis of deciduous molar morphology from the late neolithic caves of the belgian meuse basin (williams et al., 2018). the final/late collective burials of sclaigneaux and bois madame exhibit a greater range of expression of the hypoconulid, entoconulid, protostylid, carabelli’s cusp, metacone and metaconulid. although differences between the final/late neolithic cave burials of sclaigneaux and bois madame and the others from hastière rockshelter are evidenced by dental morphology, these sites likely represent ephemeral communities that experienced only limited continuity over time and were perhaps bounded as a function of distance, and to a lesser degree, by chronology. alternatively, this lack of partitioning of discrete dental traits per burial location may signal that internment was not strictly kin-based as is observed at neolithic çatalhöyük (pilloud & larsen, 2011), though larger sample sizes to conduct statistical analyses would be necessary for an investigation into potential kin relations based on dental morphology. in this study, the very low frequencies of a metaconulid and the mid-trigonal crest characterize the burials. furthermore, the expression of carabelli’s cusp on m1 and m2 joins sclaigneaux and bois madame and secondarily hastiére m and trou garçon. the greater degree of variation observed for the final/late neolithic cave burials of sclaigneaux and bois madame may have been the result of a slow but steady influx of peoples, perhaps along waterways, from other locations as a prelude to the population restructuring that occurred concomitantly with the onset of the bronze age. this seems to be the case at other locations in eurasia (subirà et al., 2014; waters-rist et al., 2016; lópez-onaindia et al., 2018). acknowledgments permission to examine these neolithic remains in belgium was kindly provided by patrick semal, chief of the scientific heritage service, royal belgian institute of natural sciences. many thanks to william anderson and laura aday for assisting in the creation of the epoxy resin dental casts. at the royal belgian institute of natural sciences, we thank caroline polet for generously assisting with the neolithic collections, and laurence cammaert who skillfully created the topographical map of belgium featured in figure 1, which we use with permission. we thank marin pilloud and the anonymous reviewers for valuable comments that significantly improved the manuscript. support for this research was provided by fulbright-belgium and the commission for educational exchange between the usa, belgium, and luxembourg. references alt, k. w., pichler, s., vach, w., klima, b., vlček, e. & sedlmeier, j. 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(2002). dental relatedness corresponding to mortuary patterning at huaca loro, peru. american journal of physical anthropology, 117, 118-121. de paepe, m. (2007). studie van de laat47 dental anthropology 2021 │ volume 34│ issue 01 neolithische menselijke resten uit een collectief graf te sclaigneaux (provincie namen, b.). ma thesis, universiteit gent. de paepe, m. & polet, c. (2007). ‘numerous and tall’: a revision of the late neolithic human remains found in a collective burial site at claigneaux (prov. namr), belgium. notæ præhistoricæ, 27, 163-168. dumbruch, i. (2003). edute du site de l’abri-sousroche du “bois-madame”, néolithique, à arbre, dans la vallée du burnot (province de namur). etude anthropologique et archéologique, volume i et ii. ma thesis, université libre de bruxelles. dumbruch, i. (2007). le site de l'abri-sous-roche du "bois-madame" à arbre (province de namur, belgique). archæologia mosellana, 7, 609612. garcía-martín, c. (2000). reconstitution du régime alimentaire par l’étude des micro-traces d’usure dentaire. master européen en anthropologie, université libre de bruxelles. hardin, a. m. & legge, s. s. (2013). geographic variation in nonmetric dental traits of the deciduous molars of pan and gorilla. international journal of primatology, 34, 1000-1019. howell, t. l. & kintigh, k. w. (1996). archaeological identification of kin groups using mortuary and biological data: an example from the american southwest. american antiquity, 61, 537-554. irish, j. d. (2006). who were the ancient egyptians? dental affinities among neolithic through postdynastic peoples. american journal of physical anthropology, 22, 529-543. jacobi, k. p. (1997). dental genetic structuring of a colonial maya cemetery, tipu, belize. in s. l. whittington & d. m. reed (eds.), bones of the maya: studies of ancient skeletons (pp. 138-153). washington: smithsonian institution press. lópez-onaindia, d. & subirà, m. e. (2017). prehistoric funerary complexity in northern iberia studied using dental morphology. homo: journal of comparative human biology, 68, 122-133. lópez-onaindia, d., coca, m., gibaja, j. f. & subirà, m. e. (2018). biological differences related to cultural variability during the neolithic in a micro-geographical area of the iberian peninsula. archaeological and anthropological sciences, 10, 1957-1969. lukacs, j. r. & pal, j. n. (2013). dental morphology of early holocene foragers of north india: non -metric trait frequencies and biological affinities. homo: journal of comparative human biology, 64, 411-436. mchugh, m. l. (2012). interrater reliability: the kappa statistic. biochemica medica 22, 276-282. orban, r., polet, c., semal, p. & leguebe, a. (2000). la stature des néolithiques mosans. bulletin de l’institut royal des sciences naturelles de belgique-sciences de la terre, 70, 207-222. pilloud, m. a. (2009). community structure at neolithic çatalhöyük: biological distance analysis of household, neighborhood, and settlement. ph.d. dissertation. the ohio state university. pilloud, m. a. & larsen, c. s. (2011). “official” and “practical” kin: inferring social and community structure from dental phenotype at neolithic çatalhöyük, turkey. american journal of physical anthropology, 145, 519-530. polet, c. (2011). les squelettes néolithiques découverts dans les grottes du basin mosan. in n. cauwe, a. hauzeur, i. jadin, c. polet & b. vanmontfort (eds.), 5200-2000 av. j.c. premiers agriculteurs en belgique (pp. 85-94). éditions du cedarc. scott, g. r. & turner, c. g., ii (1997). the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge, u.k.: cambridge university press. scott, g. r., turner, c. g., ii, townsend, g. c. & martinón-torres, m. (2018). the anthropology of modern human teeth: dental morphology and its variation in recent and fossil homo sapiens, 2nd ed. cambridge, u.k.: cambridge university press. semal, p., garcía martín, c., polet, c. & richards, m. p. (1999). considération sur l'alimentation des néolithiques du bassin mosan: usures dentaires et analyses isotopiques du collagène osseux. notæ præhistoricæ, 19, 127-135. smith, b. h. (1984). patterns of molar wear in hunter-gatherers and agriculturalists. american journal of physical anthropology, 63, 39-56. stojanowski, c. m., & schillaci, m. a. (2006). phenotypic approaches for understanding patterns of intracemetery biological variation. yearbook of physical anthropology, 49, 49-88. subirà, m. e., lópez-onaindia, d. & yll, r. (2014). cultural changes in funeral rites during the neolithic in the northeast of the iberian peninsula? the cave of pantà de foix (barcelona). international journal of osteoarchaeology, 26, 104 -113. toussaint, m. (2007). les sépultures néolithiques du basin mosan wallon et leurs relations avec les bassins de la seine et du rhin. archaeologia mosellana, 7, 507-549. 48 dental anthropology 2021 │ volume 34│ issue 01 toussaint, m., orban, r., polet, c., semal, p., bocherens, h., masy, p. & garcía martín, c. (2001). apports récents sur l’anthropologie des mésolithiques et des néolithiques mosans. anthropologica et præhistorica, 112, 91105. toussaint, m., lacroix, p., lambermont, s., lemarie, j. -f., bruzzese, l. & beaujean, j. –f. (2003). la sépulture d’enfant néolithique des nouveaux réseaux du trou du moulin, à goyet (gesves, province de namur). anthropologica et præhistorica, 116, 179-210. turner, c. g., ii, nichol, c. & scott, g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in m. a. kelley & c. s. larsen (eds.), advances in dental anthropology (pp. 13–31). new york: wiley-liss. vanderveken, s. (1997). etude anthropologique des sépultures néolithiques de maurenne et hastière (province de namur). ma thesis, université libre de bruxelles. vanderveken, s. (2007). les ossements humans néolithiques de maurenne et hastière (province de namur). notæ præhistoricæ, 17, 177-184. waters-rist, a., bazaliiskii, v. i., goriunova, o. i., weber, a. w. & katzenberg, m. a. (2016). evaluating the biological discontinuity hypothesis of cis-baikal early versus late neolithic-early bronze age populations using dental nonmetric traits. quaternary international, 405, 122-133. williams, f. l., george, r. l. & polet, c. (2018). deciduous molar morphology from the neolithic caves of the meuse river basin, belgium. dental anthropology, 31, 18-26. caspersen et al. 2010.1 37 a previous study on 42 normally developed anthropological skulls demonstrated that the direction of the infraorbital canal changes with age in the frontal view (caspersen et al., 2009). this study also indicated that the direction of the infraorbital canal reflects the transversal growth of the maxilla. previous cephalometric studies have shown that the pterygoid canal and the mandibular canal are stable structures useful for superimposing of profile radiographs and therefore valuable when evaluating craniofacial growth patterns (björk and skieller, 1977, 1983). it is assumed that the infraorbital canal also is a stable structure during growth. the infraorbital canal is located in the region of the maxilla, which has developed from the maxillary developmental field (kjær, 2009). the palatal processes of the maxilla influencing the palatal width and the maxillary canines and premolars are also located within this field (fig. 1). it is hypothesized that osseous deviations involving shape and width are expected in the maxilla in cases with dental deviations in the canine-premolar area. such deviations are ectopic maxillary canine anomalies occurring with a frequency of 0.8 to 2.8% (aydin et al., 2004) and maxillary canine transpositions occurring with a frequency below 0.4% (yilmaz et al., 2005). a dental transposition (or transmigration) occurs when teeth emerge in the wrong sequences in the dental arch, and the most common situation is when the maxillary canine emerges distal to the first premolar. maxillary canine ectopia and maxillary canine-premolar transposition are associated with deviations in the maxilla louise miltenburg caspersen, ib jarle christensen, and inger kjær department of orthodontics, institute of dentistry, faculty of health sciences, university of copenhagen, denmark abstract the purpose was to analyze the direction of the infraorbital canal and the palatal width in cases with maxillary ectopic canines, all oriented horizontally and erupted labially, and with canine transposition and to compare findings with normal values. eight anthropological human skulls, four with these horizontally oriented ectopic canines and four with canine-premolar transposition comprised the study. a radiopaque marker was placed in the infraorbital canal and frontal and profile radiographs were taken of each skull. cephalometric measurements evaluated the canal direction (iot angle). interorbital (io) and palatal widths (pw) were measured directly on the skulls. a general linear model was used for statistical analysis. maxillary canine ectopia: iot ( x = 8.54; 95% ci of -3.95 and 21.04; p = 0.18) was larger, pw ( x = 3.37; 95% ci of 0.51 and 6.23; p = 0.022) was significantly smaller and io ( x = 1.49; 95% ci of -2.62 and 5.61; p = 0.47) was also smaller. maxillary canine-premolar transposition: iot ( x = 17.27; 95% ci of 4.78 and 29.76; p = 0.008) and pw ( x = 3.34; 95% ci of 0.48 and 6.21; p = 0.023) were significantly smaller and io ( x = 2.94; 95% ci of -1.17 and 7.06; p = 0.16) was smaller, but not significantly. eruptional deviations in the maxillary canines-premolars are associated with maxillary deviations expressed as the direction of the infraorbital canal and the transpalatal width. accordingly, dental and osseous deviations within the maxillary developmental field are interrelated dental anthropology 2010;23(2):37-41. correspondence to: inger kjær, department of orthodontics, school of dentistry, faculty of health sciences, university of copenhagen, 20 nørre allé, dk-2200 copenhagen n e-mail: ik@odont.ku.dk the purpose of the present study was to analyze the direction of the infraorbital canal and the palatal width in cases either with (a) ectopic maxillary canines or (b) maxillary canine transpositions and to compare the findings with normal values. the ectopic canines were selected as possessing a horizontal orientation in the bone and these teeth had erupted labially into what would have been the subject’s buccal vestibule. materials and methods skulls eight anthropological human skulls were analyzed, four with maxillary canine ectopia, all of which were oriented horizontally and had erupted labially (2 bilateral and 2 unilateral), and four with maxillary canine-premolar transposition (2 bilateral and 2 unilateral). in the ectopia cases, the canines were malpositioned and had failed to follow the normal eruption path (fig. 2a). the skulls came from björk’s skull collection at the department of orthodontics, copenhagen school of dentistry, denmark. the results from a previous study of 42 anthropological skulls from the same collection were used as normal 38 controls (caspersen et al., 2009). registration of the infraorbital canal a radiopaque marker was placed in the infraorbital canal in the side where the maxillary canine ectopia (fig. 2a) or the maxillary canine-premolar transposition (fig. 2b) occurs. in the skulls with bilateral expressions, a marker was placed in both infraorbital canals. radiography frontal radiographs were taken of each skull as illustrated in figure 3. the radiographs were taken at the department of orthodontics, school of dentistry, copenhagen, denmark, in a philips/valmet br 2002 cephalostat (tagarno a/s, horsens, denmark) with a filmto-focus distance of 195 cm. the linear enlargement was 8.3%. the radiographic film used was liferay xda plus utlg (ferrania technologies s.p.a., cairo montenotte, italy). the films were exposed with 65-67kv and 5-7 ma. the radiographs were taken with the skulls oriented in the frankfort horizontal plane. cephalometric analysis this analysis was performed according to the method developed by caspersen et al. (2009). tracing paper was placed on each frontal radiograph, and the outer contour of the skull, the orbital rim and piriform aperture were marked. two lines were drawn: line 1 connecting the two bilateral orbital landmarks (lo) (fig. 4) and line 2 expressing the direction of the infraorbital canal (fig. 4). the bilateral orbital landmarks (lo) were defined according to svanholt and solow (1977). the angle between lines 1 and 2 (fig. 4) was named the infraorbital transversal angle (iot) (caspersen et al., 2009). direct skull measurements two widths (one anterior and one posterior) were measured on the skulls according to caspersen et al. (2009). the interorbital width (io) was the length between the left and right infraorbital foramen; this is the anterior width. the palatal width (pw) was the maxillary cross-arch transversal palatal width (from first maxillary molar; left, to first maxillary molar, right); this is the posterior width. fig. 1. on a profile radiograph of a 9 year-old girl different colored regions are marked indicating the embryological developmental fields defined by kjær (2009). the maxillary field is the focus of the present study. yellow the frontonasal field red the maxillary field (canines and premolars are in this field) orange the palatal field blue different fields in the mandible purple the theka field green the occipital field [color figure can be viewed in the electronic (pdf) version of the journal.] fig. 2. photographs of two anthropological skulls. (left) maxillary canine ectopia in the right side. the canine is oriented horizontally and has erupted labially. in this specimen, the permanent canine is lateral to the piriform plate, near the base of the nose, and the primary canine is still in occlusion. a radiopaque marker is placed in the infraorbital canal indicating the direction of the canal. (right) maxillary canine-premolar transposition in the right side. a radiopaque marker is placed in the infraorbital canal indicating the direction of the canal. l. caspersen et al. 39 statistical analysis a general linear model was used for statistical analysis of the three variables (iot, pw, and io). when the results from the ectopic and the transposition groups were compared with those of the control group, iot, pw and io were the dependent variables and the three different groups of skulls were the explanatory variables. for all explanatory variables the mean level was subtracted. the results were presented by p-values and the estimates with 95% confidence interval (ci). p-values less than 5% were considered significant. the analyses were performed using sas (version 9.1, sas institute inc., cary, n.c., usa). further, in cases with bilateral registration the skulls were tested for differences between the sides. this test showed no significant difference (p = 0.21 for iot; p = 0.91 for pw; p = 0.98 for io) and the mean value was used. this resulted in eight observations, namely four cases of maxillary labial canine ectopia (e) and four cases of maxillary canine-premolar transposition (t). results the measurements of the three variables (iot, io, and pw) for the cases with canine ectopia (e) and caninepremolar transposition (t) are shown in table 1. when all eight cases were evaluated a weak correlation was seen fig. 3. frontal radiographs of two anthropological skulls. (a) a skull with bilateral maxillary canine ectopia with a radiopaque marker in each infraorbital canal, visualized and marked by arrows. (b) a skull with bilateral maxillary canine-premolar transposition with a radiopaque marker in each infraorbital canal, visualized and marked by arrows. fig. 4. the figure illustrates the tracing on the frontal cephalometric film of an anthropological cranium from a normal human adult. line 1 represents the line through the contour of the bilateral orbital points (lo) and line 2 represents the direction of the infraorbital canal. the intersection between line 1 and line 2 forms the infraorbital transversal angle (iot), which represents the inclination of the infraorbital canal. maxillary canine ectopia and transposition 40 between iot and io (p = 0.20), whereas no correlation was seen between iot and pw or between pw and io (table 2). analysis showed that the infraorbital transversal angle (iot) ( = 8.54; 95% ci of -3.95 and 21.04; p = 0.18) was larger and that the palatal width (pw) ( x = 3.37; 95% ci of 0.51 and 6.23; p = 0.022) was significantly smaller than the mean value for the normal skulls. the interorbital width (io) ( x = 1.49; 95% ci of -2.62 and 5.61; p = 0.47) was also smaller. the infraorbital transversal angle (iot) ( x = 17.27; 95% ci of 4.78 and 29.76; p = 0.008) and the palatal width (pw) ( x = 3.34; 95% ci of 0.48 and 6.21; p = 0.023) were significantly smaller compared with the normal skulls. also, the interorbital width (io) ( x = 2.94; 95% ci of -1.17 and 7.06; p = 0.16) was smaller than the mean value in normal skulls, though not significantly. this suggests that iot and pw can be used as parameters expressing the maxillary complex in cases with maxillary canine ectopia and maxillary canine-premolar transposition. the infraorbital transversal angle (iot) may be larger and the palatal width (pw) smaller in skulls with maxillary canine ectopia compared with normal skulls, whereas the infraorbital transversal angle (iot) and the palatinal width are both smaller in skulls with maxillary canine-premolar transposition compared with normal skulls. discussion two sorts of maxillary dental deviations were studied, namely (a) canine ectopia (where the canines are oriented horizontally and erupted labially) and (b) canine transposition. analysis shows that both conditions are associated with skeletal deviations in the maxillary developmental field. this is a new observation. meanwhile, the present study cannot explain the association between dental and osseous deviations. the question is whether the dental deviations are a result of regional developmental deviations in the field or whether the regional developmental deviations in the skeleton are a result of dental deviations. this question is closely associated with the etiology of the dental deviations, which cannot be explained by the present findings. the etiology of canine ectopia and canine-premolar transposition is not known, but is assumed to be associated with multifactorial disorders involving genetic factors (feichtinger et al., 1977; peck et al., 1994). whether a difference in the infraorbital canal direction exists between the type of ectopia described in this study where the canines are oriented horizontally and erupted labially and other types of canine ectopia cannot be determined from the data in this study. also, inadequate space has been mentioned as a causative factor (al-nimri and gharaibeh, 2005). several studies have documented differences in the dentition in palatally and labially displaced ectopic canines (chaushu et al., 2002; 2003; sørensen et al., 2008). the infraorbital canal and the maxillary canine are both located in the maxillary developmental field defined by inger kjær (2009). the deviated direction of the infraorbital canal discloses a deviation in the maxilla, which may influence the tooth eruption seen in cases with canine ectopia and canine-premolar transposition. a similar comparison of tooth development and bone development within a developmental field has previously been shown in the frontonasal field of the maxilla. the present material comprising four crania with ectopia and four crania with transposition may seem small, but considering the very low prevalence of both conditions (ectopia 0.8 to 2.8% and transposition below 0.4%) the material represents a considerable population. furthermore, among the types of ectopia, horizontally oriented and labially erupted canines are considered rare. l. caspersen et al. table 1. descriptive statistic of the three variables group variable† n mean sd e iot (degrees) 4 74.63 12.33 e pw (mm) 4 34.05 1.11 e io (mm) 4 50.30 2.01 t iot (degrees) 4 48.81 7.22 t pw (mm) 4 34.08 1.77 t io (mm) 4 48.85 1.60 †iot: infra orbital transversal angle pw: palatal width io: inter orbital width. the mean value and the standard deviation are given for the four skulls with maxillary canine ectopia (e) and for the four skulls with maxillary canine/premolar transposition (t). for comparison normal values according to caspersen et al. (2009) are: iot: mean 66.08, sd 12.11 pw: mean 37.42, sd 2.85 io: mean 51.79, sd 4.13 table 2. pearson correlations among the three variables variable iot (degrees) pw (mm) io (mm) iot (degrees) 1.000 0.13 0.51 0.77 0.20 pw (mm) 0.13 1.000 0.01 0.77 0.99 io (mm) 0.51 0.01 1.000 0.20 0.99 correlation coefficients: n = 4; prob > |r| under h0: rho = 0 correlation between the three variables (iot, pw and io) in the 8 skulls with canine ectopia and canine/premolar transposition by pearson correlation coefficients. the table shows a weak correlation between iot and oi (p = 0.20), whereas the other variables are not significantly correlated. 41 regarding the frontonasal field, the tooth deviation seen in smmci (single median maxillary central incisor) has been associated with regional osseous deviations within the frontonasal field including the anterior wall of the sella turcica (kjær et al., 2001; becktor et al., 2001). the extension of the frontonasal field is demonstrated in figure 1 (yellow color). it is recommended that the morphology of the sella turcica be investigated systematically in all cases of dental deviations in future studies. the sagittal and vertical growth of the cranium can also affect the direction of the infraorbital canal, but in the present study only the frontal view was investigated because canine ectopia is often diagnosed in the frontal view on a panoramic radiograph. in the present study, the transverse width of the palate has been measured as an indicator of transverse growth in the mid-palatal suture. under normal circumstances, palatal expansion is characterized by more extensive growth in the posterior region than anteriorly (iseri and solow, 1990). it seems that this usual pattern of growth does not occur in the cases evaluated in the present study. the present study documents a statistically significant correlation between the direction of the infraorbital canal, maxillary morphology, and deviations in tooth eruption in the maxilla. it can be concluded that the maxillary dimensions are different in ectopia and transposition, and that the maxillary dimensions differ from normal findings. acknowledgements the faculty of health sciences, university of copenhagen, denmark, is acknowledged for founding. helena schatz is acknowledged for professional assistance with the radiographic procedure. maria kvetny is acknowledged for linguistic support and manuscript preparation. literature cited al-nimri k, gharaibeh t. 2005. space conditions and dental and occlusal features in patients with palatally impacted maxillary canines: an aetiological study. eur j orthod 27:461-465. aydin u, yilmaz hh, yildirim d. 2004. incidence of canine impaction and transmigration in a patient population. dentomaxillofac radiol 33:164-169. becktor kb, sverrild l, pallisgaard c, burhøj j, kjær i. 2001. eruption of the central incisor, the intermaxillary suture, and maxillary growth in patients with a single median maxillary central incisor, smmci. acta odontol scand 59:361-366. björk a, skieller v. 1977. growth of the maxilla in three dimensions as revealed radiographically by the implant method. br j orthod 4:53-64. björk a, skieller v. 1983. normal and abnormal growth of the mandible: a synthesis of longitudinal cephalometric implant studies over a period of 25 years. eur j orthod 5:1-46. caspersen lm, christensen ij, kjær i. 2009. inclination of the infraorbital canal studied on dry skulls expresses the maxillary growth pattern—a new contribution to the understanding of change in inclination of ectopic canines during puberty. acta odontol scand 17:1-5. chaushu s, sharabi s, becker a. 2002. dental morphologic characteristics of normal versus delayed developing dentitions with palatally displaced canines. am j orthod dentofacial orthop 121:339-346. chaushu s, sharabi s, becker a. 2003. tooth size in dentitions with buccal canine ectopia. eur j orthod 25:485-491. feichtinger c, rossiwall b, wunderer h. 1977. canine transposition as autosomal recessive trait in an inbred kindred. j dent res 56:1449-1452. iseri h, solow b. 1990. growth displacement of the maxilla in girls studied by implant method. eur j orthod 12:389-398. kjær i. 2010. orthodontics and foetal pathology: a personal view on craniofacial patterning. eur j orthod 32:40-47. kjær i, becktor kb, lisson j, gormsen c, russell bg. 2001. face, palate and craniofacial morphology in patients with a solitary median maxillary central incisor. eur j orthod 23:63-73. peck s, peck l, kataja m. 1994. the palatally displaced canine as a dental anomaly of genetic origin. angle orthod 64:249-256. svanholt p, solow b. 1977. assessment of midline discrepancies in the postero-anterior cephalometric radiograph. trans eur orthod soc 25:261-268. sørensen hb, artmann l, larsen hj, kjær i. 2008. radiographic assessment of dental anomalies in patients with ectopic maxillary canines. int j paediatr dent 19:108-114. yilmaz hh, türkkahraman h, sayin mö. 2005. prevalence of tooth transpositions and associated dental anomalies in a turkish population. dentomaxillofac radiol 34:3235. maxillary canine ectopia and transposition capasso and di tota 1993.3 pg4.jpg pg5.jpg pg6.jpg pg7.jpg hasewaga et al. 2010.2 7 carabelli trait is expressed on the mesio-palatal surface of human maxillary molar crowns, particularly primary second and permanent first molars, and the feature shows a quasi-continuous pattern of expression (harris, 1977). investigations of carabelli trait, one of many so-called nonmetric dental crown traits, are usually based on classifying or scoring the feature with reference to standard plaques, leading to calculations of its frequency of occurrence and degree of expression. although most investigations of carabelli trait have used standard plaques, there are distinct differences in reported frequencies of the trait in similar population groups, probably resulting more from observational inconsistencies than true variation (scott, 1980). misclassification of the trait is further compounded by the relatively large number of different classification methods available to the researcher (kieser and merwe, 1984). recently, the effect of inter-observer errors was reported when using dental morphological features to calculate genetic distances in ancient mayans, with different ‘cut points’ for determining presence and absence of traits, such as carabelli trait, influencing the outcomes of the analyses (cucina and wrobel, 2008). although carabelli trait has been studied extensively within and among human populations, there is still uncertainty about the validity of the different methods of classification, including which is the most suitable to use in primary and permanent dentitions. twin studies provide a valuable approach for clarifying the relative contributions of genetic and environmental effects to phenotypic variability (eaves, 1982; townsend et al., 2009). indeed, a study of carabelli trait in the permanent dentition of south australian twins indicated a very strong genetic contribution to observed variation, with an estimate of heritability around 90% (townsend and martin, 1992). pinkerton et al. (1999) extended this earlier investigation by analysing the expression of carabelli trait in both the primary and permanent dentitions of a large sample of australian twins, highlighting the importance of genetic influences on carabelli trait variation and disclosing patterns of variation in trait expression between dentitions. the aim of our present study was to explore the reliability and validity of two methods for classifying carabelli trait (hanihara, 1961; dahlberg, 1963), by scoring the feature in both primary and permanent dentitions of a sample of australian twins. by examining trait expression within and between the dentitions of monozygotic (mz) twin pairs we also aimed to gain some insight into the underlying causes of observed variation, and to clarify which phenotypic forms of carabelli trait might be more closely related in terms of their ontogeny. given the strong genetic influence on variation in carabelli trait, carabelli trait in australian twins: reliability and validity of different scoring systems yuh hasegawa,*,1, 2 james rogers,2 graham scriven2 and grant townsend2 1school of life dentistry, the nippon dental university, niigata, japan; 2school of dentistry, the university of adelaide, adelaide, south australia abstract we assessed the intraand inter-observer reliability of two methods of scoring or categorizing carabelli trait in both primary and permanent dentitions (hanihara, 1961; dahlberg, 1963). by using dental casts obtained from twins, we also compared the expression of carabelli trait within and between monozygotic (mz) co-twins to clarify the ontogenetic processes leading to different forms of trait expression. while intra-observer concordance rates were generally good (70 90%), inter-observer concordance rates were poor (35 60%). this indicates that considerable caution is needed when comparing data for carabelli trait derived from different samples by different researchers. by comparing categories or scores for carabelli trait in both dentitions of mz co-twins, we found inter-relationships between groove and cuspal forms of the feature. although the arizona state university system developed by turner is commonly used nowadays to score the carabelli trait, we would encourage researchers interested in clarifying genetic influences and ontogenetic processes in both dentitions to refer to the often over-looked plaque of hanihara and also dahlberg’s plaque p12b. this should improve the reliability and validity of data obtained by helping to clarify the inter-relationships between the different phenotypic expressions of carabelli trait. dental anthropology 2010;23(1):7-15. *dr. hasegawa performed this research while on sabbatical leave as a visiting lecturer in the school of dentistry, the university of adelaide. correspondence to: yuh hasegawa, school of life dentistry at niigata, the nippon dental university, 1-8, hamaura-chou, chuuou-ku, niigata-city, niigata, japan 951-8580 e-mail: haseyu@ngt.ndu.ac.jp 8 it was hypothesized that any differences in phenotypic expression of the trait within and between mz co-twins would tend to be small, reflecting environmental and/or epigenetic influences operating during odontogenesis. by comparing classifications or scores for carabelli trait using the different methods, we aimed to shed light on the validity of the systems, including their ability to reflect ontogenetic processes. materials and methods a total of 200 sets of dental casts, representing 50 pairs of monozygotic (mz) and 50 pairs of dizygotic (dz) twins, were examined and scored for carabelli trait, using the systems of hanihara (1961) and dahlberg (1963). the dental casts were selected from a collection of over 600 pairs housed in the school of dentistry at the university of adelaide. the twins were all of european ancestry and their ages ranged from 8.3 years to 11.5 years, with a mean age of 9.5 years. zygosities were confirmed either by comparison of genetic markers in the blood or by dna analysis of buccal cells (townsend and martin, 1992). the probability of monozygosity, given concordance for all the systems that were analysed, was greater than 99.0%. the ongoing study of teeth and faces of australian twins was approved by the committee on the ethics of human experimentation, the university of adelaide (approval no. h/07/84a), and all participants have provided informed consent. the methods of hanihara (1961) and dahlberg (1963) were used to classify carabelli trait on primary maxillary second molars and permanent maxillary first molars, respectively. plaster replicas of the standard plaques provided by dahlberg (1956) and hanihara (1961) were used to facilitate standardization in scoring. dahlberg originally produced two plaques, p12a and p12b, with the ‘p’ denoting ‘preliminary’ (figs. 1a, b). the former fig. 1b. dahlberg’s less known plaque p12b for classifying carabelli trait, highlighting groove-cusp morphology. there are eight categories represented: (a) a groove around a large cusp (same as ‘h’ in p12a); (b) a groove on the mesial of a small cusp (same as ‘e’ in p12a); (c) a groove on the distal of a cusp (no equivalent in p12a); (d ) a groove on both sides of a cusp (same as ‘f’ in p12a); (e) an elevation of cusp but no grooves (no equivalent in p12a); (f) a pit (same as ‘c’ in p12a); (g) completely smooth surface (same as ‘a’ in p12a). fig. 1a. dahlberg’s plaque p12a for classifying carabelli trait, highlighting increasing size of the feature. there are eight categories represented: (a) no expression; (b) a furrow; (c) a pit; (d) double grooves; (e) a y-shaped groove; (f) a small cusp; (g) a larger cusp; (h) a large cusp. y. hasegawa et al. 9 intraand inter-observer reliability in scoring carabelli trait, and plaque p12b was used to provide additional insights into variability in trait expression in selected pairs of mz twins. although dahlberg stressed his plaque p12b should not be used to define classes of carabelli trait, he emphasized that pit and grooves should be noted in addition to cuspal forms. hanihara’s plaque d7 was also used to score carabelli trait, with the ‘d’ referring to ‘deciduous’ (fig. 2). it presents eight categories of carabelli trait and has been used to interpret the relationship between pit and cuspal forms in the primary dentition. assessments were made by one observer for all subjects on two separate occasions, enabling an estimation of the intra-observer reliability of both methods to be made. two broad categories, referred to as ‘concavities’ and ‘convexities’, were used to compare intra-observer concordance rates using the methods of both hanihara and dahlberg. the ‘concavities’ category included scores 0 to 3 in hanihara’s system and categories a-d in dahlberg’s p12a system. the ‘convexities’ category included scores 4 to 7 in hanihara’s system and categories ‘e-g’ in dahlberg’s p12a system. in his analysis of the american indian dentition, dahlberg (1963) grouped the ‘b’ and ‘c’ categories together to represent various types of grooves and pits, and then combined the categories ‘d’ to ‘g’ to represent all sizes of cusps. we have chosen to include category ‘d’ as a ‘concavity’ for the purposes of our reliability tests, reflecting the presence of two grooves or furrows. to assess inter-observer reliability, ten pairs of twins were selected at random and classified for carabelli trait by three observers using the methods of dahlberg and hanihara. these three observers had different amounts of experience in classifying carabelli trait. observer a was a person with considerable experience, observer b had one year of experience, and it was the first time that observer c had scored carabelli trait. after making their observations, inter-observer concordance rates between the three observers were calculated. chi-square tests were also performed to compare the scoring of carabelli trait between methods with statistical significance set at an alpha level = 0.05. after assessing reliability, carabelli trait was reexamined in all pairs of mz twins where co-twins showed discordant expression of the feature by referring to both of dahlberg’s plaques, p12a and p12b, as well as hanihara’s d7 plaque. given the recognized strong genetic contribution to variation of the trait, it was considered that close examination of those mz twin pairs who showed different degrees of expression of the feature on primary and permanent teeth, or between sides, would provide additional insights into the validity of the scoring systems and also into the underlying biological processes leading to the observed phenotypes. carabelli trait in australian twins fig. 2. hanihara’s plaque d7 developed for scoring carabelli trait in the primary dentition. there are eight grades: (0) no expression; (1) a shallow groove; (2) a shallow depression; (3) a deeper depression or pit but no bulge; (4) similar to 3 but a slight eminence; (5) a stronger eminence but smooth; (6) a cusp encircled by a groove; (7) a strong cusp. has been commonly used for categorizing the size of carabelli trait in the permanent dentition, whereas the latter, less well-known plaque was designed to highlight groove-cusp morphology, following on from descriptions by meredith and hixon (1953). dahlberg created plaque p12b with the intention of evaluating pits and other surface irregularities found at the sites commonly occupied by carabelli cusp. he suggested that, for future reference, pits and grooves should be counted as features relative to carabelli trait, and that plaque p12b might be used to provide a limited guide to the trait’s development (dahlberg, 1956). in this study, plaque p12a was used for assessing 10 results table 1 shows the intra-observer concordance rates for scoring carabelli trait on two separate occasions for primary second molars. values ranged from around 70% to 90% reflecting good intra-observer reliability. a significant difference in concordance rates between the scoring methods was noted for ‘concavities’ in the dz sample. in the ‘convexities’ category there was a significant difference in concordance rates between the methods for mz twins and for the total sample (table 1). table 2 shows the concordance rates between first and second assessments for permanent first molars. values ranged from 75% to 85%. no significant differences in either the ‘concavities’ or ‘convexities’ categories were found between the methods. table 3 indicates the inter-observer concordance rates among the three observers for scoring carabelli trait on primary second molars and table 4 provides similar data for permanent first molars. the concordance rates were generally low, highlighting that inter-observer reliability for scoring was relatively poor. using the method of hanihara, the concordance rate between observer a and c was highest, followed by the rate between observer b and c, and the rate between observer a and b was lowest for both primary second molars and permanent first molars. using hanihara’s method, the concordance rate between observer a and c was 65% for primary second molars and 40% for permanent first molars. the concordance rates between observer b and c, and between observer a and b, were around 35% for both hanihara dahlberg concordance discordance concordance discordance n % n % total significance n % n % total total 315 78.8 85 21.3 400 ns 301 75.3 99 24.8 400 dz 158 79.0 42 21.0 200 ns 152 76.0 48 24.0 200 mz 157 78.5 43 21.5 200 ns 149 74.5 51 25.5 200 concavity 224 78.6 61 21.4 285 ns 229 73.6 82 26.4 311 dz 106 78.5 29 21.5 135 ns 110 72.8 41 27.2 151 mz 118 78.7 32 21.3 150 ns 119 74.4 41 25.6 160 convexity 91 79.1 24 20.9 115 ns 72 80.9 17 19.1 89 dz 52 80.0 13 20.0 65 ns 42 85.7 7 14.3 49 mz 39 78.0 11 22.0 50 ns 30 75.0 10 25.0 40 ns: not significant *0.05 > p > 0.01; **p < 0.01 table 2. concordance rates between first and second assessments (permanent first molars) y. hasegawa et al. hanihara dahlberg concordance discordance concordance discordance n % n % total significance n % n % total total 305 76.3 95 23.8 400 ns 297 74.3 103 25.8 400 dz 152 76.0 48 24.0 200 ns 138 69.0 62 31.0 200 mz 153 76.5 47 23.5 200 ns 159 79.5 41 20.5 200 concavity 242 78.3 67 21.7 309 ns 253 72.1 98 27.9 351 dz 118 78.1 33 21.9 151 * 115 66.1 59 33.9 174 mz 124 78.5 34 21.5 158 ns 138 78.0 39 22.0 177 convexity 63 69.2 28 30.8 91 ** 44 89.8 5 10.2 49 dz 34 69.4 15 30.6 49 ns 23 88.5 3 11.5 26 mz 29 69.0 13 31.0 42 ns 21 91.3 2 8.7 23 ns: not significant *0.05 > p > 0.01; **p < 0.01 table 1. concordance rates between first and second assessments (primary second molars) 11 primary second molars and permanent first molars. using the method of dahlberg with plaque p12a, the concordance rate between observer b and c was 62.5% and the rates between observer a and b and between observer a and c were each 47.5% for primary second molars. the concordance rate between observer a and b was 47.5% and the rate between observer a and c was 45%, but the rate between observer b and c was only 35% for permanent first molars. there were differences between observers regarding the interpretation of what constituted a groove or an eminence in both hanihara’s and dahlberg’s systems. the observers also had difficulty in classifying both the pit and y-shaped categories using hanihara’s system, and there were differences in interpretation between the groove, y-shaped, and cuspal grades in dahlberg’s system. where there were differences in classification or scoring of carabelli trait within or between mz cotwins, the differences tended to be small, as we had hypothesized. by examining closely the cases where there were differences between sides or between primary and permanent dentitions within an mz twin, or differences between mz co-twins, we were able to gain some insight into the ability of the different classification systems to reflect the phenotypic variation observed, and also to clarify how each category or score related to others. figures 3 and 4 represent two pairs of mz twins who were selected because they showed discordant expressions of carabelli trait that assisted in considering the validity of the dahlberg and hanihara systems. table 5 shows the categories and scores for the trait, based on dahlberg’s plaques p12a and p12b, and also using hanihara’s plaque, for both the primary second molars and the permanent first molars in these two pairs of twins. the results provided in table 5 were obtained by three observers each scoring the feature independently, then reaching a consensus on which category or score best matched the phenotypic expressions observed. it can be seen that there were differences in expression both within and between the twin pairs. for example, the primary and permanent molars for t331a were all scored as category ‘b’ according to dahlberg’s plaque observer a observer b observer c hanihara’s dahlberg’s hanihara’s dahlberg’s hanihara’s dahlberg’s method method method method method method observer a concordance ----13 (32.5%) 19 (47.5%) 26 (65.0%) 19 (47.5%) discordance ----27 (67.5%) 21 (52.5%) 14 (35.0%) 21 (52.5%) observer b concordance 13 (32.5%) 19 (47.5%) ----15 (37.5%) 25 (62.5%) discordance 27 (67.5%) 21 (52.5%) ----25 (62.5%) 15 (37.5%) observer c concordance 26 (65.0%) 19 (47.5%) 15 (37.5%) 25 (62.5%) ---- discordance 14 (35.0%) 21 (52.5%) 25 (62.5%) 15 (37.5%) ----(n = 40; sum of left and right sides) table 3. concordance rates among three observers (primary second molars) carabelli trait in australian twins fig. 4. a pair of mz twins (t338a and b) showing different expressions of carabelli trait within and between co-twins. the categories or scores are summarized in table 5. fig. 3. a pair of mz twins (t331a and b) showing different expressions of carabelli trait within and between co-twins. the categories or scores are summarized in table 5. 12 observer a observer b observer c hanihara’s dahlberg’s hanihara’s dahlberg’s hanihara’s dahlberg’s method method method method method method observer a concordance ----13 (32.5%) 19 (47.5%) 16 (40.0%) 18 (45.0%) discordance ----27 (67.5%) 21 (52.5%) 24 (60.0%) 22 (55.0%) observer b concordance 13 (32.5%) 19 (47.5%) ----14 (35.0%) 14 (35.0%) discordance 27 (67.5%) 21 (52.5%) ----26 (65.0%) 26 (65.0%) observer c concordance 16 (40.0%) 18 (45.0%) 14 (35.0%) 14 (35.0%) ---- discordance 24 (60.0%) 22 (55.0%) 26 (65.0%) 26 (65.0%) ----(n = 40; sum of left and right) table 4. concordance rates among three observers (permanent first molars) t331a t331b deciduous m2 permanent m1 deciduous m2 permanent m1 right left right left right left right left side side side side side side side side dahlberg’s plaque 12a b b b d b e e e dahlberg’s plaque 12b e e e nc e b b b hanihara’s plaque d7 1 1 1 nc 1 3 2 3 t338a t338b deciduous m2 permanent m1 deciduous m2 permanent m1 right left right left right left right left side side side side side side side side dahlberg’s plaque 12a e h b a e c a b dahlberg’s plaque 12b b a e h b g h e hanihara’s plaque d7 4 6 1 0 3 2 0 1 there is no equivalent category in dahlberg’s plaque p12b or hanihara’s plaque d7 to category ‘d’ in dahlberg’s plaque p12a . nc = no category. table 5. categories and scores of carabelli trait expression in two pairs of monozygotic twins y. hasegawa et al. p12a, except for the permanent left first molar that was scored as category ‘d’. the co-twin, t331b, displayed a ‘b’ category for the primary right second molar but all of the other teeth were scored as category ‘e’. the corresponding categories and scores based on dahlberg’s plaque p12b and on hanihara’s d7 plaque, are also shown in table 5. similarly, there were differences in the categories and scores recorded for twins t338a and b. in these cases, the expression of carabelli trait was greater on the primary molars than the permanent teeth, and there were also differences in expression between sides and between co-twins. the reader is encouraged to view the figures carefully and then to score the different teeth in both sets of twins. it becomes evident that the different phenotypic forms of carabelli trait do seem to be linked to each other but there are many forms of the feature that are difficult to classify with any certainty. discussion the method of dahlberg (1963) has been used commonly by many researchers to classify carabelli trait on permanent first molars, although there have been numerous scoring methods developed over the years, including shapiro’s (1949) nine-grade classification, goose and lee’s (1971) five-grade classification and alvesalo et al.’s (1975) five-grade classification. currently, the most widely used method for classifying carabelli trait in the permanent dentition is the arizona state university dental anthropology system devised by christy g. turner and his colleagues (turner et al., 1991). this method is based on dahlberg’s plaque p12a but the categorical classification system of dahlberg has been replaced by a numerical system from 0 to 7. the categories and the scores match reasonably well, although scores 3 and 4 in turner ’s system refer to small and large y-shaped 13 depressions, whereas categories ‘d’ and ‘e’ on dahlberg’s plaque p12a represent a double groove and a y-shaped groove, respectively. dahlberg’s p12a plaque includes absence and seven degrees of expression of carabelli trait, ranging from a single groove (or so-called ‘furrow’), a pit, a double groove, a y-shaped groove, to various sizes of cusps. in this scheme, categories ‘f ‘to ‘h’ represent increasing sizes of cusp. however, his p12b plaque does not address any size sequence, rather it considers pit-groove relationships. although this plaque does not appear to have been used very widely in the past, it did assist the observers in this study to focus on the inter-relationship among pits, furrows and grooves, and cusps of various sizes. in cases where carabelli trait was difficult to categorize, reference to p12b provided additional guidance in deciding which category to choose. although dahlberg’s method was developed for the permanent dentition, it has been used to score carabelli trait in both the primary and mixed dentitions (pinkerton et al., 1999) with additional reference to the plaque of hanihara (1961). as this study progressed it became clearer that there were some discrepancies in the expression of carabelli trait between the primary and permanent dentitions. the primary molars tended to display a higher frequency of y-shaped groove forms, whereas cuspal forms were more common in the permanent dentition. this finding has been reported previously by other researchers (saunders and mayhall, 1982; pinkerton et al., 1999; adler, 2006). kieser (1984) examined the expression of carabelli trait on primary and permanent molars and reported a high degree of equivalence of expression of carabelli trait in both dentitions. he hypothesized that this result was consistent with low epigenetic but high genetic influence on carabelli trait expression. we have noted previously that, if the trait appears on the permanent first molar of an individual, it is almost always present on the primary second molar. however, if the trait appears on the primary molar, it may not be expressed on the permanent molar. consistent with kieser ’s view, we have interpreted this finding as reflecting similar underlying genetic influence for carabelli trait in both dentitions, with environmental and/or epigenetic influences being more likely to modify trait expression on the permanent molar that forms later and develops over a longer period of time (townsend and brown, 1981). the plaque d7 of hanihara was designed specifically to score carabelli trait in the primary dentition and, therefore, some limitations were noted when attempting to use it to score different convexity categories in the permanent teeth. interestingly, hanihara’s description of his system does not refer to y-shaped grooves specifically, rather the term ‘depression’ is used. nevertheless, the examples of depressions provided on hanihara’s plaques do have a characteristic y-shaped appearance. dahlberg’s p12a system provides a comprehensive categorization of the cuspal categories of the trait but it does not address the peculiarities of the various pit/groove relationships to any extent. for example, it is often difficult to decide whether a short groove that ends in a deeper depression should be classed as a groove or a pit. it is also often difficult to determine whether double grooves lie either side of a slight elevation that would warrant a cuspal classification. similarly, y-shaped grooves may or may not be associated with a convexity of the lingual surface of the tooth. despite these difficulties, it appears that an acceptable level of intra-observer reliability can be reached for scoring carabelli trait using the methods of either dahlberg or hanihara. we achieved concordance values in the range of 70-90%. observers tend to develop their own internal calibration for classifying difficult examples of the trait that is based on their interpretation of the system of classification being used. it would appear that it is probably best to use the dahlberg system when classifying carabelli trait in the permanent dentition and the hanihara system in the primary dentition, while acknowledging that each method has its limitations. however, the level of inter-observer reliability was very low whichever method was used in either dentition. our concordance values were in the range of only 3560%. this finding reinforces the view that considerable caution is needed when making comparisons of data for carabelli trait derived from different samples by different researchers. for studies of the mixed dentition, where a uniform system of classifying carabelli trait on both primary and permanent molars is desirable, it is suggested that a modified system could be used that draws on the methods of both hanihara and dahlberg. it is interesting that the arizona state university (asu) system for classifying carabelli trait in the permanent dentition is slightly different from the system proposed originally by dahlberg, with the ‘double groove’ category of dahlberg replaced by a ‘y-shaped groove’ category (turner et al., 1991; dahlberg, 1963). even though it was developed for the permanent dentition, the asu system, with its use of scores rather than categories and its modification of the original dahlberg system, provides an additional very useful perspective for attempting to classify the range of expression of carabelli trait in both dentitions. although distinguishing and classifying minor differences in phenotypic expression of carabelli trait may not be as important in population-based anthropological studies as deciding whether the trait is present or not, we contend that fine discrimination in phenotypic expression is desirable in genetic studies and also in clarifying ontogenetic processes. we would propose for these types of studies that all available reference sources should be considered, including dahlberg’s plaque p12b, to assist in describing and then recording the rather complex inter-relationships between grooves and cusps. the variations in expression of carabelli trait demonstrated in the two pairs of mz twins reported carabelli trait in australian twins 14 in this paper highlight the wide range of expressions of the trait that are possible and confirm that no single scoring system is likely to be able to capture all possible phenotypic forms. the two examples we have provided also support the view that, despite a strong over-riding genetic influence on observed variation, relatively minor modifications in environmental and/or epigenetic influences within or between co-twins can apparently lead to different phenotypic expressions in carabelli trait. the types of expressions of carabelli trait observed within the mz co-twins, particularly in terms of the expression of different groove forms, confirm that there is an inter-relatedness between groove forms and cuspal forms of the trait. our findings in twins suggest that increasing expression of carabelli trait follows a continuum from simple grooves, to pits, to double grooves, to y-shaped grooves, and then to cusps of various sizes, in a similar order to that represented in dahlberg’s plaque p12a. even though carabelli trait has probably been studied by dental anthropologists more than any other dental feature, there is still much to learn about the nature of the ontogenetic mechanisms that lead to its various expressions on primary and permanent molar teeth. we would strongly encourage researchers who are planning to study carabelli trait to refer to the the plaque of hanihara and plaque p12b of dahlberg prior to commencing any study, as these earlier, often over-looked works, provide valuable insights into the rationale and limitations of the classification systems used most commonly nowadays, for example, the asu system which is based on dahlberg’s plaque p12a. one area that deserves further exploration is comparison of the expression of carabelli trait on the external surface of dental crowns with its expression at the dentino-enamel junction, a structure that reflects the folding of the internal enamel epithelium of the developing tooth. researchers such as kraus (1952), korenhof (1963), sasaki and kanazawa (1999), avishai et al. (2004) and skinner et al. (2009) have all explored the morphology of the dentino-enamel junction using different approaches. we plan to extend these studies by applying micro-ct scanning to exfoliated molar teeth of mz twins where there are differences in phenotypic expression of carabelli trait within and between co-twins. in conclusion, we would like to reiterate the comments of mayhall (1999) who emphasized the need for “more and better genetic studies” of dental morphological traits and the need to improve our understanding of “why the traits we observe are as they appear.” acknowledgements the support of the national health and medical research council of australia is gratefully acknowledged. we particularly thank the twins and their families who have agreed to participate in the research project and the australian twin registry for their continuing assistance. the assistance of ms. sandra pinkerton and dr daniela ribeiro is also greatly appreciated. literature cited adler c. 2006. sexual dimorphism in the 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western australia, nedlands, p 19-28. sasaki k, kanazawa e. 1999. morphological traits on the dentino-enamel junction of lower deciduous molar series. in: mayhall jt, heikkinen t, editors. proceedings of the 11th international symposium on dental morphology, oulu, finland, 1198. oulu university press, oulu, finland, p 167-178. saunders sr, mayhall jt. 1982. developmental patterns of human dental morphological traits. arch oral biol 27:45-49. scott gr. 1980. population variation of carabelli’s trait. hum biol 52:63-78. shapiro mmj. 1949. the anatomy and morphology of the tubercle of carabelli. j dent assoc south africa 4:355362. skinner mm, gunz p, wood ba, hublin j-j. 2009 how many landmarks? assessing the classification accuracy of pan lower molars using a geometric morphometric analysis of the occlusal basin as seen at the enamel-dentine junction. in: koppe t, meyer g, alt kw, editors. comparative dental morphology, frontiers in oral biology. basel: karger. p 23-29. townsend gc, brown t. 1981. the carabelli trait in australian aboriginal dentition. arch oral biol 26:809-814. townsend gc, martin ng. 1992. fitting genetic models to carabelli trait data in south australian twins. j dent res 71:403-409. townsend g, hughes t, luciano m, brook a. 2009. genetic and environmental influences on human dental variation: limitations and advantages of studies involving twins. arch oral biol 54s1:s45-s51. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, spencer larsen cs, editors. advances in dental anthropology, new york: wiley-liss, p 13-31. alsoleihat and khraisat 2011.4 25 the study of dental morphological traits has been used extensively by dental morphologists, anthropologist and paleontologists for characterization and assessment of the biological relationships within and among ancestral, recent and living major subdivisions of humankind, and to a lesser extent for racial diagnosis in the field of forensic odontology (dahlberg 1965b, 1986; turner, 1987a; scott and turner, 1988, 1997; irish, 1993; and others). dental morphological traits have been shown to be largely under the control of genes and minimally affected by environmental factors (scott and dahlberg, 1982; corruccini et al., 1986; sofaer et al., 1986), and have also been described to be genetically conservative, exhibiting minimal modification over many generations (scott and turner, 1988). however, the general evolutionary trend in the modern human dentition has been described to be toward morphologic simplification and tooth size reduction (scott and turner, 1988). the utility of inter-population variation in the frequencies of dental non-metric (morphological) traits for measuring the biological distance between human populations has been well-demonstrated (scott and turner, 1997). such biological distance values provide summary values that encapsulate the overall difference in the expression frequencies of these traits between two groups (scott and turner, 1997). morphological or phenetic distances based on inter-population variation *correspondence to: firas alsoleihat, department of conservative dentistry, faculty of dentistry, university of jordan, amman, 11942 jordan tel: (+962) 777 946631 e-mail: firas.alsoleihat@ju.edu.jo the phenetic distances of jordanian arabs from other human populations suggest a major genetic drift from the caucasoid race firas alsoleihat* and ameen khraisat department of conservative dentistry and fixed prosthodontics, faculty of dentistry, university of jordan, amman, jordan 11942 abstract the objectives were to determine the expression frequency and sexual dimorphism of 16 nonmetric crown traits on the permanent dentitions of the living jordanians, and to assess the biological affinity of this sample to 21 high-order groups based on these traits. 360 jordanian school children (176 males, 184 females; mean ages 15.5, sd = 0.4 years) were studied in 2009. the traits were classified using the arizona state university dental anthropology system, counted with the individual count method, and dichotomized according to scott and turner criteria for the purpose of group comparisons. z-value test was used to assess sexual dimorphism in these traits. smith’s mean measure of divergence was used to measure all pairwise distance values among the groups. sexual dimorphism was found in only three traits (i.e., carabelli’s tubercle/ cusp, metaconule and hypoconulid absence). this study revealed that the dental pattern of living jordanians is sufficiently distinct from the caucasoid pattern and all other known dental patterns to warrant a unique dental pattern for this population. moreover, the relatively large distance values between the living jordanians and all other world groups considered including the western eurasian groups suggest a major genetic drift for this population from the caucasoid race. dental anthroology 2011;24:23-30. in the frequencies of dental morphological traits have been shown to be powerful in assessing biological affinity between population groups, since these traits have a strong heritable component (scott and turner, 1997). in general, small inter-group distances indicate that these groups are biologically similar and have a recent common ancestor, while large values are associated with biological dissimilarity and remote common ancestry (scott and turner, 1997). however, significant admixture (gene flow) between groups leads to convergence which can change the original biological distance between these groups (scott and turner, 1997). the dental pattern of living jordanian arabs has not been comprehensively studied before, and the biological affinity of this population for other geographic races has not been assessed. sexual dimorphism for dental morphological traits has been investigated by many workers, and the reported results are not always consistent and appear to show geographic variation among various world groups. an exception of this is the distal accessory ridge 26 of the upper and lower canines which exhibits consistent dimorphism between males and females across diverse groups (scott, 1977a; kaul and prakash, 1981; kieser and preston, 1981; scott et al., 1983). apart from this variable, some researchers have found statistically significant male-female differences in the expression of some dental morphological traits such as carabelli’s trait (goose and lee, 1971; kaul and prakash, 1981; kieser and preston, 1981; townsend and brown, 1981b, scott et al., 1983; mizoguchi, 1985) and upper central incisor shoveling (rothhammer et al., 1968; harris, 1980) while others found no sex difference for carabelli’s trait (garn et al., 1966d; turner, 1969; scott, 1980; townsend et al., 1992) and the shoveling trait (aas and risnes, 1979a; mizoguchi, 1985). the aims of the present study were, first, to investigate the frequencies and sexual dimorphism of 16 dental morphological traits, that are observable on dental stone casts on the permanent dentition of the living jordanian arabs, and, second, to assess the biological affinity of the living jordanians in a global context by measuring all of the pairwise biological distances among this group and 21 other high-order regional groups from the five major subdivisions of humankind based on the variation of frequencies of the dental traits. materials and methods sample and inclusion criteria a random stratified sample was obtained in 2009 by selecting 370 tenth grade school children (180 males and 190 females), from 12 schools representing the six regional directories of the capital city of jordan, amman. informed consents were obtained from the parents of all children who chose to participate in the study before the children were subjected to dental examination or impression taking. the average age of the selected subjects was 15 years (sd = 0.4). they were selected according to the following criteria: all subjects were apparently healthy with no history of serious childhood illnesses, have erupted second molars, showing well aligned arches with no supernumerary teeth and no history of orthodontic treatment, with normal appearing teeth, no large restorations or fixed replacements, and minimal marks of caries or attrition. alginate impressions for the upper and lower dental arches were taken (lascod s.p.a, firenze, italy). impressions were poured with type iv dental stone (elite stone, zhermack s.p.a, badia polesine, italy) within one hour of impression taking. casts of ten subjects were excluded due to technical errors such as air bubbles. the remaining casts were of 176 male and 184 female students. observation method sixteen morphological tooth crown traits were observed and classified according to the standard plaques of the arizona state university dental anthropology system (turner et al., 1991). all observations were carried out by under good lighting and using 10x hand lenses. the individual count method was used here to estimate the frequency of expression of the dental morphological traits. according to this method, the antimere exhibiting the highest grade of trait expression is used for statistical analysis (scott and turner, 1997). this method was chosen because it assigns each individual a phenotypic value that is thought to best represent the individual genotype and it does not artificially inflate the sample size like the total side (tooth) count method (scott and turner, 1997). such increase in sample size would affect most statistical analyses (scott and turner, 1997). intraobserver error all observations for these morphological traits were carried out by one well-trained observer. intra-observer reliability for scoring these traits was assessed according to nichol and turner criteria (1986). 30 dental casts out of the present sample were selected, to be scored by the single observer, and rescored by the same observer three months later. care was taken to reproduce the percentages of males and females in this sample as in the original sample of 360 casts. percentages of disagreements that are of two grades or more between the two scoring sessions (>1 grade variant scoring %) were calculated for the traits considered here and found to be less than the critical value of 10% as set by nichol and turner (1986) who justified that traits generating greater than 10% disagreement of two or more grades between two scoring sessions are difficult to reliably score since they reflect either recording error, inaccurate observational method, or difficulties with standard plaque itself rather than the natural difficulty in the ability to consistently classify individuals exhibiting intermediate trait expression between two grade standards on a ranked scale. in addition, the net mean grade difference (nmgd) between the two scoring sessions was calculated for these traits using the formula nmgd = (σ (x2-x1)/n) × 100 where x1 = the grade number assigned to a cast for a trait in the first scoring session; x2 = the grade number assigned to the same cast for the same trait in the second scoring session; and n is the number of casts that were observed in both of the scoring sessions. the calculated nmgd value for each trait considered here was found below the critical level of nmgd for that trait, which is > 5% multiplied by the number of the highest grade on the grading standard for that trait. furthermore, the differences between the mean scores of the two scoring sessions for these traits were f. alsoleihat and a. khraisat 27 estimated using the paired sample t-test and the t-values were found to be below the critical 0.05 probability level adjusted by bonferroni’s method (miller, 1966; nichol and turner, 1986). it should be noted that dental morphological traits are ordinal scale variables and the t-test is an interval scale statistics, however, since the graded scales for scoring these traits were designed so that the variation in expression of these traits is divided into equal intervals from the least to greatest expression (scott, 1973), it is justifiable, according to nichol and turner (1986), to use the t-test with non-metric dental traits based on the assumption that the classification grades are equally spaced on the ranked scales for these traits. given the foregoing values (the values of the >1 grade variant scoring %, of nmgd and the t-values), it can be concluded that the scoring of these traits is reliable and that the intra-observer error in scoring these traits can be considered random and statistically insignificant. statistical analysis and visual depiction social science statistical package software (spss, version 17.0, inc., chicago, il) was used to analyze the data. frequencies were calculated for crown traits and dichotomized according to scott and turner criteria (1997) for the purpose of group comparisons to quantify their relative prevalence among the living jordanian sample. z-value test was used to test any significant difference in trait expression between males and females using software available on the following website: (http://www.dimensionresearch.com/resources/ calculators/ztest.html). for the purpose of affinity assessment, the biological distances among the living jordanians and 21 highorder regional groups from the five major subdivision of humankind were measured using cab smith’s mean measure of divergence (mmd) based on the variation in the frequencies of expression of 16 non-metric tooth crown traits among these groups (constandsewestermann, 1972; harris and sjøvold, 2004). this analysis was based on our own data for the frequencies of these traits among the living jordanians and on the data available in scott and turner (1997) regarding the frequencies of the same traits among the other 21 regional groups and the corresponding sample sizes. anscombe’s angular transformation formula was adopted here to transform frequencies into angles for calculating the smith’s mmd in order to stabilize sampling variances of binomial variables, since this formula is the recommended angular transformation method by rao (1952) for moderately large samples (harris and sjøvold, 2004). it should be noted that the mmd value between any two groups being compared was measured as recommended by harris and sjøvold (2004) by calculating the differences between the two groups in angularly transformed frequencies of each trait, then this difference is squared so that positive and negative differences do not cancel one another, then the correction term ((1/n1k + 0.5)+(1/n2k + 0.5)) is subtracted from this squared difference for each trait (hence the subscript k) in order to adjust for the overestimation of divergence between corresponding groups generated by the squared difference between two angular values, then the resultant values for all traits used in the equation are summed and then the sum is divided by the number of these traits (harris and sjøvold, 2004). the resultant matrix of distance values corresponding to all pairwise comparisons among the 22 groups was used to derive two coordinates (two-dimensional ordination) for each group through multidimensional scaling using spss statistics 17.0 in order to reduce the complexities of the distance matrix to two dimensions and to provide graphical representation for the biological distances among the 22 groups considered. results crown trait frequencies table 1 summarizes the frequencies of 16 nonmetric dental crown traits, on the permanent dentition in both sexes among the living jordanian sample. by comparing the frequencies of the 16 traits among the living jordanians with the world ranges of these traits, it is apparent that the dental pattern of the living jordanians shows distinctly high frequencies of double shoveling on ui1, carabelli’s trait and cusp 5 (metaconule) on um1; high frequencies of interruption grooves on ui2, hypocone absence (3-cusped form) on um2 and bushmen canine trait on uc; intermediate frequencies of shoveling on ui1, hypoconulid absence on lm2, deflecting wrinkle, cusp 6 and 7 on lm1; low frequencies of bilateral winging of ui1s, y pattern on lm2, hypoconulid absence and distal trigonid crest on lm1, and absence of premolar odontomes (table 1). sexual dimorphism statistically significant male-female differences were found in only three of the 16 dental morphological traits. these include the carabelli’s trait (tubercle and cusp forms only) and cusp 5 (distal accessory tubercle, metaconule) on um1, and hypoconulid absence (4-cusped form) on lm1. in the first two traits the difference is in favor of males while in the third one it is in favor of females (table 1). phenetic distances among 22 regional groupings table 2 shows a matrix of all the pairwise biological distances among 22 high-order regional groupings including the living jordanian arabs based on intergroup variation in the frequencies of the 16 crown traits. phenetic distances of living jordanians 28 table 1. frequencies of 16 dental morphological traits among the living jordanians (individual count, affected individuals/ total number of subjects in parentheses) trait world percent percent percent name tooth breakpoint range males females z-value (sexes pooled) winging ui1 grade 1 4.2-50.0% 8.0% 8.7% 0.067 8.3% (bilateral winging) (14/176) (16/184) (30/360 shoveling ui1 grades 3-6 (hrdlicka’s 0.0-91.9% 55.7% 56.0% -0.049 55.8% semiand full-shovel) (98/176) (103/184) (201/360) double ui1 grades 2-6 0.0-70.5% 98.3% 94.6% 1.614 96.4% shoveling (173/176) (174/184) (347/360) interruption ui2 grade 1 10.4-65.0% 63.6% 61.4% 0.328 62.5% grooves (total frequency) (112/176) (113/184) (225/360) bushmen uc grades 1-3 0.0-35.1% 30.7% 27.2% 0.618 28.9% canine (total frequency) (54/176) (50/184) (104/360) odontomes upms and grade 1 0.0-6.5% 0.0% 0.0% __ 0.0% lpms (total frequency) (0/176) (0/184) (0/360) 3-cusped um2 grades 0-1 3.3-30.6% 26.7% 19.0% 1.611 22.8% (equivalent to 3 (47/176) (35/184) (82/360) on dahlberg scale) carabelli’s um1 grades 5-7 1.9-36.0% 51.7% 34.8% 3.134a 43.1% trait (tubercle and (64/184) (91/176) (155/360) cusp forms only) cusp 5 um1 grades 1-5 10.4-62.5% 69.3% 57.6% 2.195a 63.3% (total frequency) (122/176) (106/184) (228/360) 4-cusped lm1 grade 0 0.0-10.0% 0.0% 3.8% 2.228a 1.9% (4-cusped lm1) (0/176) (7/184) (7/360) 4-cusped lm2 grade 0 4.4-84.4% 73.3% 81.0% 1.611 77.2 (4-cusped) (129/176) (149/184) (278/360) y pattern lm2 y pattern 7.6-71.9% 21.0% 19.0% 0.342 20.0% (37/176) (35/184) (72/360) cusp 6 lm1 grades 1-5 4.7-61.7% 17.6% 13.6% 0.907 15.6% (total frequency) (31/176) (25/184) (56/360) cusp 7 lm1 grades 1-4 3.1-43.7% 21.0% 15.2% 1.293 18.1% (total frequency (37/176) (28/184) (65/360) excluding grade 1a) deflecting lm1 grade 3 4.9-39.5% 23.3% 19.0% 0.866 21.1% wrinkle (41/176) (35/184) (76/360) distal lm1 grade 1 0.0-18.7% 5.7% 9.8% 1.255 7.8% trigonid crest (presence) (10/176) (18/184) (28/360) athe difference is statistically significant at the 0.05 probability level (2-tailed). ui1: upper central incisor; ui2: upper lateral incisor; uc: upper canine; upms: upper first and second premolars; lpms: lower first and second premolars; um1: upper first molar; um2: upper second molar; lm1: lower first molar; lm2: lower second molar f. alsoleihat and a. khraisat 29 jo r w e n e n a w a sa k h c m jo m jr n e s ss a a n w a n sa i se e se r po m i a u s n g m l jo r .0 00 w e .6 21 .0 00 n e .6 05 .0 35 .0 00 n a .5 25 .0 20 .0 34 .0 00 w a .7 23 .4 01 .3 88 .2 92 .0 00 sa .7 22 .1 75 .1 83 .1 03 .1 02 .0 00 k h .8 40 .3 44 .4 28 .2 54 .1 16 .0 82 .0 00 c m .4 31 .3 85 .3 97 .3 12 .3 61 .3 26 .4 45 .0 00 jo m .6 94 .2 18 .2 43 .2 04 .2 91 .2 11 .3 17 .1 81 .0 00 jr .5 20 .3 66 .4 03 .3 13 .3 51 .3 03 .3 99 .0 61 .1 36 .0 00 n e s .5 78 .4 84 .5 05 .4 19 .4 19 .3 68 .4 59 .0 64 .1 97 .0 40 .0 00 ss .3 59 .1 28 .1 50 .0 92 .2 94 .1 81 .2 93 .1 10 .1 00 .0 99 .1 70 .0 00 a a .6 10 .5 50 .5 74 .4 97 .5 21 .4 55 .5 59 .0 91 .2 07 .0 59 .0 16 .2 10 .0 00 n w a .5 40 .7 13 .7 20 .6 19 .6 06 .6 00 .6 95 .0 85 .3 33 .0 99 .0 42 .2 88 .0 43 .0 00 n sa i .5 47 .8 45 .8 36 .7 24 .6 92 .7 05 .8 12 .1 27 .4 61 .1 66 .0 90 .3 74 .1 16 .0 23 .0 00 se e .4 40 .2 08 .2 03 .1 52 .1 73 .1 55 .2 65 .0 65 .0 89 .0 64 .1 09 .0 45 .1 73 .2 15 .2 85 .0 00 se r .4 62 .1 85 .1 94 .1 35 .1 75 .1 35 .2 37 .0 65 .0 96 .0 55 .1 24 .0 41 .1 83 .2 47 .3 21 .0 04 .0 00 po .5 77 .1 99 .1 76 .1 57 .1 42 .1 45 .2 79 .1 36 .0 73 .1 20 .2 02 .0 93 .2 60 .3 38 .4 34 .0 20 .0 28 .0 00 m i .5 81 .2 53 .2 59 .2 05 .1 60 .1 61 .2 43 .0 91 .1 07 .0 77 .1 03 .1 02 .1 86 .2 43 .3 04 .0 12 .0 16 .0 33 .0 00 a u s .7 33 .3 78 .3 27 .3 05 .1 26 .1 99 .3 20 .2 01 .1 75 .1 79 .2 67 .2 38 .3 21 .3 91 .4 99 .0 95 .0 96 .0 47 .0 92 .0 00 n g .7 27 .0 92 .0 64 .0 51 .1 98 .0 85 .2 24 .4 21 .2 15 .4 17 .5 53 .2 06 .6 36 .7 78 .9 02 .1 93 .1 77 .1 34 .2 21 .2 15 .0 00 m l .6 03 .1 68 .1 13 .1 17 .1 11 .0 97 .2 57 .2 35 .1 40 .2 32 .3 09 .1 33 .3 90 .4 86 .5 73 .0 60 .0 68 .0 24 .0 72 .0 85 .0 65 .0 00 t a b le 2 . d is ta nc e m at ri x am on g 22 r eg io na l g ro up in gs in cl ud in g th e liv in g jo rd an ia n a ra bs (c .a .b . s m it h’ s m ea n m ea su re o f d iv er ge nc e (m m d ) v al ue s) jo r : j or d an ; w e : w es te rn e ur op e; n e : n or th er n e ur op e; n a : n or th a fr ic a; w a : w es t a fr ic a; s a : s ou th a fr ic a; k h : k ho is an ; c m : c hi na m on go lia ; j o : j om on ; j r : j ap an (r ec en t) ; n e s: n or th ea st s ib er ia ; s s: s ou th s ib er ia ; a a : a m er ic an a rc ti c; n w a : n or th w es t n or th a m er ic a; n sa i: n or th a nd s ou th a m er ic an in d ia n; s e e : s ou th ea st a si a (e ar ly ); se r : s ou th ea st a si a (r ec en t) ; p o : p ol yn es ia ; m i: m ic ro ne si a; a u s: a us tr al ia ; n g : n ew g ui ne a; m l : m el an es ia phenetic distances of living jordanians 30 fig. 1. two-dimensional ordination based on multidimensional scaling of distance matrix for 16 non-metric crown traits in 22 regional groupings including the living jordanian arabs. abbreviations are: jor: jordan; we: western europe; northe: northern europe; na: north africa; wa: west africa; sa: south africa; kh: khoisan; cm: china-mongolia; jo: jomon; jr: japan (recent); nes: northeast siberia; ss: south siberia; aa: american arctic; nwa: northwest north america; nsai: north and south american indian; see: southeast asia (early); ser: southeast asia (recent); po: polynesia; mi: micronesia; aus: australia; ng: new guinea; ml: melanesia f. alsoleihat and a. khraisat none of the 21 regional groups is found apparently biologically close to the living jordanians; however, the smaller distance values to the living jordanians are those corresponding to south siberia, china-mongolia and southeast asia (recent and prehistoric) and, surprisingly, not to western eurasian groups (western europe, northern europe and north africa). figure 1 provides a visual representation of the distance matrix shown in table 2 by reducing these values to two dimensions through multidimensional scaling. it shows that the living jordanian arabs appear as an outlier and do not cluster with any of the 21 regional groups. however, relatively speaking, the jordanian groups appear closer to south siberia, chinamongolia and southeast asia than to western eurasian groups. discussion dental morphological pattern of living jordanians the results of this study revealed that the living jordanian arabs have a unique dental morphological pattern exhibiting outstandingly high frequencies of ui1 double shoveling and um1 carabelli’s tubercle/cusp forms that set this population apart from other world groups. moreover, this population falls at the high end of the global scale for five crown traits (i.e., um1 cusp 5, ui2 interruption grooves, 3-cusped um2, 4-cusped lm2, and uc bushmen canine trait). in addition, ui1 shoveling assumes high intermediate position on the world range for this population group. additionally, this group shows intermediate frequencies for deflecting 31 wrinkle, cusp 6 and 7 on lm1. the remainder of crown traits described is at the low end of world variation (i.e., ui1s bilateral winging, lm2 y pattern, 4-cusped lm1, lm1 distal trigonid crest; and premolar odontomes). this pattern is apparently distinct from the western eurasian, or caucasoid, dental pattern, which is characterized by (a) high frequencies of 4-cusped lower first and second molars, carabelli’s tubercle/cusp, and 3-cusped upper second molars, but the latter two traits are not distinctly high in this regional subdivision and are nearly equaled by groups in other regions, (b) intermediate frequencies of ui2 interruption grooves and lm2 y pattern; and (c) low frequencies of the remainder of the crown traits described (i.e., winging, shoveling, double shoveling, bushmen canine, metaconule, cusp 6, cusp 7, deflecting wrinkle, distal trigonid crest, and premolar odontomes) (scott and turner, 1997). to summarize, the dental morphological pattern of living jordanian arabs is characterized by trait elaboration in contrast to that of western eurasians, which is felt by many researchers to be distinguished more by trait rarity or absence than trait elaboration (mayhall et al., 1982; scott and turner, 1997). sexual dimorphism sexual dimorphism among the living jordanians was found statistically significant in only three out of the 16 crown traits described (i.e., um1 cusp 5, um1 carabelli’s tubercle/cusp forms and 4-cusped lm1), where the first two variables are more frequent in males and the latter shows a higher occurrence in females, indicating a stronger trend toward crown morphological reduction or simplification in females among the living jordanian arabs, and this reduction trend involves not only accessory tubercles and cusps but also major cusps of molar teeth. as mentioned before, it seems that there are differences among populations regarding the sexual dimorphism in the expression of carabelli’s trait; many workers found statistically significant male-female differences in favor of males (goose and lee, 1971; kaul and prakash, 1981; kieser and preston, 1981; townsend and brown, 1981b, scott et al., 1983; mizoguchi, 1985), but others find no sex difference for this trait (garn et al., 1966d; turner, 1969; scott, 1980; townsend et al., 1992). consistent with our results regarding the sexual dimorphism in um1 carabelli’s tubercle/cusp and 4-cusped lm1 is the report that carabelli’s trait in upper molars and hypoconulid expression (5-cusped form) in lower molars are less frequent in individuals with turner syndrome (xo or 45,x) than their relatives (kirveskari and alvesalo, 1982). these findings suggest a role for the x chromosome in favoring crown morphological simplification versus a balancing effect of the y chromosome in retaining crown morphological complexity. biological affinity of living jordanians the biological distance values between the living jordanians and 21 high-order groups from the five major subdivisions of humankind based on the 16 crown traits described, as well as the visual depiction of the distance matrix described based on multidimensional scaling, show that the living jordanians are phenetically distant from the western eurasian groups and all other world groups. these suggest that the living jordanian population has undergone a major genetic drift that set the dental phenotype of this population apart from that of the western eurasian groups included in the analysis (i.e., western europeans, northern europeans and north africans). although less in magnitude, similar dental morphological differentiation among groups having recent common ancestral relationships has been well documented in the middle eastern jews (sofaer et al., 1986), the southwest american indians (scott and dahlberg, 1982; scott et al., 1983), the yanomama indians of venezuela (brewer-carias et al., 1976), and melanesians (harris, 1977). such genetic drifts leading to local differentiation in dental morphology among biologically related groups over a relatively short period are generally viewed as a consequence of colonization events, population structure such as high rates of endogamy, and small population size (scott and turner, 1988). conclusions this study revealed that the living jordanian arabs have a unique dental morphological pattern that sets this group apart from the western eurasian and other world groups. this pattern, in contrast to that of the western eurasian, is characterized by more trait elaboration than trait rarity or absence. statistically significant sexual dimorphism has been found in the occurrence of three crown traits in the direction of stronger trend toward crown morphological simplification in females involving accessory tubercles as well as minor and major cusps in the molar region. the relatively large biological distance values of the living jordanians from the western eurasian groups, with whom they share a recent common ancestor, suggest that this population has undergone a major genetic drift leading to a distinct dental morphological pattern for this population from the caucasoid dental pattern over a relatively short time span. literature cited aas ihm, risnes s. 1979a. the depth of the lingual fossa in permanent incisors of norwegians. i. method of measurement, statistical distribution and sex dimorphism. am j phys anthropol 50:335-340. brewer-carias ca, le blanc s, neel jv. 1976. genetic structure of a tribal population, the yanomama phenetic distances of living jordanians 32 indians. xii. dental microdifferentiation. am j phys anthropol 44:5-14. constandse-westermann ts. 1972. coefficients of biological distance. oosterhout n. b. the netherlands: anthropological publications. corruccini rs, sharma k, potter rh. 1986. comparative genetic 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interpretations from the dentition. am j phys anthropol 30:421-426. turner cg ii. 1987a. late pleistocene and holocene population history of east asia based on dental variation. am j phys anthropol 73:305-321. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larson cs, editors. advances in dental anthropology. new york: wiley-liss. p 13-31. kato et al. 2011.1 studies of tooth crown morphology are essential in human biology and phylogeny. in particular, dental morphological traits have been recognized for their importance as a phenotypic expression of genetic differences between groups (ohno, 1986; irish, 1998). traditional standard morphological analysis for comparing dental traits is performed by visual morphological observations (hanihara, 1954, 1955; suzuki and sakai, 1966; mizoguchi, 1977, 1978), which has a long history of making significant contributions to dental science. the approach is generally based on quantifying the relative expressions and frequencies of discrete traits by a standard reference plaque. on the other hand, it has been reported that grading by standardized plaque is susceptible to interand intra-observer measurement errors (mizoguchi, 1977; turner and hanihara, 1977; nichol and turner ii, 1986; haydenblit, 1996). haydenblit (1996) reported that the percentage of intra-observer error greater than a onegrade scoring difference was 5.4% for 20 maxillary dental traits and 4.7% for 20 mandibular dental traits. additionally, inter-observer error in the >1-grade variant-scoring percentage for a total of 47 traits ranged from 0.0% to 40.0%. mizoguchi (1978) estimated percent discordances between duplicated observations on the same sample; he reported a value of 10.7% for shoveling in the central incisor, though he emphasized that discordances are negligible in most cases unless there is obvious misjudgement. although the difficulty associated with discrimination among tooth crown grades depends on type of tooth character and degree of expression, in some instances observational estimation can influence the consequential outcome. therefore, objective approaches to classify tooth crown characteristics are desirable. the aims of the present study were (1) to explore the differences between subjectively discriminated grading with standard plaque and objectively distinguished grading with geometric morphometrics, and (2) to determine whether the outer enamel surface (oes) or dentinoenamel junction (dej) form in tooth crown distinguishes the existence of shovel shape among a variety of maxillary central incisor morphologies. from the perspective of dental anthropology, tooth crown morphology is consequential for taxonomy as the grouping variable. as a preliminary investigation, we a geometric morphometric analysis of the crown form of the maxillary central incisor in humans akiko kato1*, makiko kouchi2, masaaki mochimaru2, ayamoto isomura1, and norikazu ohno1 1department of oral anatomy, school of dentistry, aichi-gakuin university, 1-100 kusumoto-cho, chikusa-ku, nagoya 464-8650, japan 2digital human research center, national institute of advanced industrial science and technology, 2-41-6 aomi, koto-ku, tokyo 135-0064, japan *correspondence to: akiko kato, department of oral anatomy, school of dentistry, aichi-gakuin university, 1-100 kusumoto-cho, chikusa-ku, nagoya 464-8650, japan tel: +81-52-751-2561; fax: +81-52-752-5988 e-mail: a-kato@dpc.aichi-gakuin.ac.jp abstract dental traits have been studied over a long period and grossly evaluated using standard reference plaques. however, grading by subjective observation may result in inter-observer measurement errors. we aimed to analyze crown models three-dimensionally to assess the morphology of the lingual surface termed shovel shape. micro-ct scanned data of 38 maxillary central incisors stored at two different laboratories were used to create crown models of the outer enamel surface (oes) and the dentinoenamel junction (dej). original crown data were evaluated according to the grade of shoveling into weak and strong groups. homologous models consisting of the same number of data points were created and the distance matrices between tooth models of oes and dej were respectively analyzed by using multidimensional scaling analysis (mds) and principal component analysis. student’s t-test was used to compare corresponding scores between the two groups based on shovel-shape. the results of a t-test in the oes model indicated significant differences between the two groups. in contrast, the result in the dej model did not reveal a statistically significant difference. our results indicate that geometric morphometric analysis of microct scanned tooth crowns represents a powerful solution for the objective shape assessment of human teeth. dental anthropology 2011;24(1):1-10. 2 focused on shovel shape as the tooth crown character, which was first described by hrdlička (1920). we adopted the arizona state university (asu) dental anthropology system (turner et al., 1991) for visual discrimination. this is a frequently-used standard for evaluating dental traits (irish, 1998; irish and guatelli-steinberg, 2003; manabe et al., 2003, 2008; nwe aung et al., 2005; suzuki, 2005; sasaki et al., 2005). we also performed morphometric analysis with three-dimensional (3d) tooth data from various populations for objective discrimination. for objective evaluation of 3d data, the database of anthropometry of human data is globally available and can be commercially applied (kouchi and mochimaru, 2004, 2010; mochimaru and kouchi, 2000). unlike the 2d data, 3d data have significance in detecting group average form. a homologous modeling method was developed to classify 3d body forms (mochimaru et al., 1999; mochimaru and kouchi, 2000; kouchi and mochimaru, 2006), which is applied for designing products that fit to human body shape. the basic modeling technology based on subdivisions of the surface has been developed and applied to foot shape and body shape (mochimaru et al., 1999; kouchi and mochimaru, 2010). this method allows computation of the average and variability of 3d body shapes in a sample. in the present study, we applied homologous modeling and compared the tooth crown shape related to oes and dej. a homologous model can represent the tooth as shape data with the same number of data points of the same topology. finally, we discuss the differences between the results of grading with an ordinal-scale plaque and those obtained from morphometric analysis, exploring the possibility of geometric morphometrics to evaluate 3d tooth crown shape. table 1. maxillary central incisor data used in this study ethnic group na wsb ssc data source japanese 23 (22) 9 (12) 14 (10) original agu indians 2 (2) 2 (2) 0 original agu burmese 2 (2) 2 (2) 0 original agu nepalese 1 (1) 1 (1) 0 original agu caucasian 6 (3) 6 (3) 0 ct b&h pacific-islander 1 (0) 1 (0) 0 ct b&h african-american 3 (2) 3 (2) 0 ct b&h totals 38 (32) 24 (22) 14 (10) an, sample size bws, weak shoveling (asu: 0-2) css, strong shoveling (asu: 3-6) dagu, aichi-gakuin university, japan; b&h, brown and herbranson imaging, inc., ca, usa numbers indicate dentinoenamel junction (dej) data numbers in parenthese show outer enamel surface (oes) data fig. 1. diagram of homologous crown model creation. lingual surfaces of two examples (sample no. 1 and 2 are shown). template crown models of the oes (a) and the dej (b) were used to construct homologous models. kato et al. 3crown form of maxillary central incisor materials and methods study sample micro-ct scanned data of 38 permanent upper left central incisors were obtained for geometric morphometric analysis of oes and dej of tooth crown. table 1 lists the human populations from which the incisors used in this study were obtained. japanese, indians from india, burmese and nepalese incisors stored at aichi-gakuin university (agu) were scanned by micro-ct (smx225ct, shimadzu, kyoto, japan) at an isometric voxel resolution of 60 microns (70 kv, 50μa, 512/512 matrix, 600 views, 360 degrees of rotation, 10 frame averaging). ct scan data of caucasian, pacific-islander and africanamerican teeth were provided by brown and herbranson imaging, inc. (b&h, palo alto, ca, usa). the details of the b&h ct scan data were as follows: raw projection data of 16 bit, image size of 580/579/989 matrix and resolution of 20-60 microns isotropic cube. incisors were grouped into two classes based on the shoveling grade of the asu dental anthropology system. observations of the shovel shape for b&h data were necessarily made from 3d models. as analyses based fig. 2a. depiction of the 40 landmarks used for oes surface model in this study. on the sum of shovel and semi-shovel grade were more appropriate to reduce the observational error (suzuki and sakai, 1966), the data were grouped into asu grades 0-through-2 as the weak shoveling group (ws) and asu grades 3-through-6 as the strong shoveling group (ss). six incisors that had enamel defects or caries were excluded from oes analysis in this study. the total numbers of teeth in ws and ss for oes analysis were 22 and 10, while those in ws and ss for dej analysis were 24 and 14, respectively. right incisor data were mirror-imaged during 3d image reconstruction processing (described in the next section) in order to maximize the sample size. to reduce the size of the resulting files, image stacks were downsampled to 60 microns. homologous model creation figure 1 shows a diagram of homologous model creation. an image stack was imported into reconstruction software (vgstudio max 2.0, volume graphics, gmbh, heidelberg, germany). during 3d image reconstruction, right incisor data were mirror-imaged to the left incisor. after calibration to define material and background, enamel and dentine tissues were segmented using fig. 2a. 40 landmarks used for oes surface model in this study. 4 the distribution of grayscale threshold values on its histogram, which arises from differences of mineralization of enamel and dentine. then, the oes and dej form were respectively reconstructed as a triangulated surface model. before constructing a homologous model, we produced template crown models of the oes or the dej crown shape consisting of about 700 polygons using geomagic studio 9 (geomagic, inc., durham, nc, usa). a template crown model exhibiting the shape of the enamel surface was produced from a segmented tooth crown enamel cap. in addition, the template crown model of the dentinoenamel junction shape was produced by substituting with the inner surface of the enamel cap model. that way, template models of the oes and dej were constructed and landmarks were applied on the model (fig. 2a,b). 40 vertices for the oes model and 37 vertices for the dej model were manually assigned to anatomical landmarks. the template oes model had three more landmarks than the dej, and these were related to the thickness of the incisal edge. the template model automatically fits into the individual scanned point cloud of the maxillary central incisors by minimizing external and internal energy functions. the external energy function is based on the euclidian distance between data points of the template model and those of the scanned data. the internal energy function is based on the local deformation of the template model. the vertices of the template model specified as landmarks were fit into the landmarks, and vertices generated by the subdivision surface were fit into measured point clouds with minimal deformation of the initial template model. as described above, the oes and dej homologous models were created for each sample by using homologous body modeling software (hbm, digital human technology inc., tokyo, japan) and hbm-rugle (medic engineering corporation, kyoto, japan). coordinate system figure 3 illustrates the coordinate system used for crown model orientation. the z-axis was the crown axis direction passing through the center of the horizontal cross-section of the highest point on the labial cervical line (landmark 22) and the highest point on the lingual cervical line (landmark 25), through the central point on the incisal edge (landmark 2). the x-axis was in the labiolingual direction passing the landmark 25 orthogonal table 2. means, standard deviations and differences for measurements of zyxdirectional length of polygon models obtained from ct scanned data agu b&h differences percentage mean (mm) sd mean (mm) sd agu:b&h (mm) error a z 22.13 0.8 22.58 0.9 0.45 2.0 y 8.59 0.5 8.65 0.5 0.04 0.5 x 6.86 0.2 7.23 0.6 0.38 5.5 b after standardization z 20.00 0.0 20.00 0.0 0.00 0.0 y 7.77 0.5 7.69 0.5 0.08 1.0 x 6.20 0.3 6.42 0.7 0.22 3.5 n = 6 fig. 3. orientation of the oes model (a) and dej model (b). lm 2, lm 22, and lm 25 stand for the central point on the incisal edge, the center of the horizontal cross section of the highest point on the labial cervical line, and the highest point on the lingual cervical line, respectively. kato et al. 5 to the z-axis. the y-axis was in the mesiodistal direction. the origin (0, 0, 0) was the intersection point of the x-axis and the z-axis. landmark 2 was made to lie at (0, 0, 100) in each specimen in order to remove differences in crown height. inter-system comparison to assess the comparability of ct systems, we examined the possible measurement error of ct scanned data from two institutes. six maxillary central incisors were scanned by both ct systems (agu and b&h). external surface models of the whole teeth were created by vgstudio max 2.0. for inter-system comparison, the coordinate system used for crown model orientation was used and the length from central point on incisal edge to apical point of the root was scaled to be 20 mm. the size of polygon models was measured using the software. the shape errors between two polygon models were calculated. statistical analysis the distance between the two models was defined as the sum of the euclidean distances between corresponding data points. the distance matrix between 32 models for oes and that between 38 models for dej was analyzed by the multidimensional scaling (mds) method and principal component analysis (pca). mds is one of the factor analyses used to determine the spatial configuration of objects (wickelmaier, 2003). mds detects meaningful underlying dimensions that allow us to explain observed similarities or dissimilarities between objects. it generally attempts to arrange objects in a space with a particular number of dimensions, explaining the distance matrix in terms of fewer underlying dimensions to reduce the observed complexity of nature (borg and groenen, 2005; bronstein et al., 2006). on the other hand, pca, which is used in many studies (stefan and trinkaus, 1998; hlusko and mahaney, 2007; bastier et al., 2008; morimoto et al., 2008), summarizes data variation into fewer principal components corresponding to axes that account for the largest, second largest, and successively smaller proportion of the total sample variance. kouchi and mochimaru (2006) assessed the usefulness of pca and mds in analyzing variations in intra-individual shape change patterns and compared them. they reported that mds is more efficient in information compression, so we assessed homologous models with mds in addition to pca to compare the information obtained from each analysis using human body statistica (hbs, digital human technologies inc., tokyo, japan). mds and pca scores in the ws and ss groups were compared by student’s t-test for oes or dej analyses. statistical analysis was performed using statistical software (spss 15.0j for windows, spss japan inc., tokyo, japan). in order to interpret the obtained dimensions by mds and pca, virtual shapes with scores of ±3 s.d. for each of the three axes showing significant differences were calculated by using hbs (mochimaru and kouchi, 2000). results inter-system comparison six polygon models constructed by the authors from data acquired at agu and b&h were measured. table 2a provides averages and standard deviations of tooth length, labiolingual diameter, and mesiodistal diameter substituted by the length along the z-axis, x-axis, and table 3. significance probability (p value) from student ttest between mds scores of ws group and those of ss group for all dimensions dimension oesa dejb 1 0.49 0.10 2 0.27 0.14 3 0.43 0.21 4 0.44 0.77 5 0.001** 0.07 aouter enamel surface bdentinoenamel junction **p < 0.01 table 4. significance probability (p value) from student t-test between pca scores of ws group and those of ss group for all pcs. pca oesb dejc 01 0.82 0.84 02 0.22 0.02* 03 0.55 0.58 04 0.08 0.18 05 0.09 0.25 06 0.31 0.36 07 0.21 0.72 08 0.03* 0.17 09 0.59 0.09 10 0.01** 0.06 11 0.20 0.27 12 0.74 0.54 13 0.74 0.17 14 0.71 ___ 15 0.26 ___ 16 0.67 ___ aprincipal component bouter enamel surface cdentinoenamel junction *0.05 > p > 0.01 **p < 0.01 crown form of maxillary central incisor 6 y-axis, respectively. the percent errors between the two systems ranged from 0.5% to 5.5%. based on these results, the length of the present model was standardized. table 2b shows the measured values after standardization. the percent errors between the two systems ranged from 0.0% to 3.5%. mds scores a five-dimension solution was adopted for both the oes and dej analyses because r2 (squared correlation coefficient) was high (oes, 0.84; dej, 0.94). table 3 shows the level of significance (p value) of the student’s t-test between mds scores of the ws group and ss group for all dimensions. as mds calculates spatial configuration of objects, the calculated factor of differences is called “dimension.” the first dimension has the highest variance and each succeeding dimension in turn has the higher variance that is uncorrelated with the preceding dimension. significant differences were found in only dimension-5 (p < 0.01) between the ws and ss groups in the oes model. however, no significant difference in the dej model was observed. based on the calculated mds score in dimension-5 for the oes model, virtual shape models within -3 sd to +3 sd of the average were created. figure 4 shows a scatter plot of mds scores in dimension-5 for the oes model of the ws and ss groups. virtual shape models with +3 sd and -3 sd across dimension-5 axis are indicated at the ends of the axis. by observing the virtual shapes, mds space can be interpreted over the axes. it was found that dimension-5 related to thickness of the incisal edge and size of the mesial and distal marginal ridges in addition to the relative depth of the lingual surface. pca scores almost 100% of total variance was explained by 16 pcs for the oes and 13 pcs for the dej. table 4 shows the p values of the student’s t-test between pca scores of the ws and ss group for all principal components. in pca, significant differences in the oes model between the ws and ss groups were found in pc8 (p < 0.05) and pc10 (p < 0.01). the first 10 pcs explain 82.3% of total variance. on the other hand, significant differences in dej were seen in pc2 (p < 0.05). the first two pcs explain 41.9% of total variance. however, it is difficult to explain this component seen in the dej model. this is because the virtual shape expressed labiolingual thickness and mesiodistal length in addition to the depth of the lingual hollow. this means that the pc2 axis was not directly related to the shovel shape despite significant differences between pca scores of the ws and ss groups. thus, this component of dej model could be ignored. figure 5 shows a scatter plot of pca scores in pc8 and pc10 for the oes model of the ws and ss groups. virtual shape models within the +3 sd and -3 sd interval across each axis are indicated at the end of these axes. pc8 axis for the oes model was related to thickness of the incisal edge and size of the marginal ridge in parallel fig. 4. scatter plot of mds scores in dimension-5 (dim-5) for the oes model of ws and ss groups. +3 sd and -3 sd virtual shape models across dimension-5 axis are indicated at the both end of the axis. kato et al. 7 with shovel depth. pc10 for the oes model was related to the presence of the slope face (incline) following the lingual cingulum. discussion in the present study, the shoveling group subjectively discriminated with standard plaque corresponded to those groups objectively discriminated with 3d homologous crown models of outer enamel surface shape. in this section, we discuss some of the major issues and approaches involved in the acquisition of ct scanned data from different systems, and then we discuss the results of the present study. recent studies using micro-ct have contributed to our knowledge by evaluating a non-invasive method to analyze objects (kono et al., 2002; suwa and kono, 2005; smith and tafforeau, 2008; olejniczak et al., 2008). olejniczak and grine (2006) compared physical sections to computer-generated micro-ct sections of recent primate teeth, and a difference of 3% to 5% was indicated between them. their report revealed that measurement with the greatest care under proper conditions makes micro-ct useful. furthermore, olejniczak et al. (2007) compared different micro-ct systems to ensure that results are comparable and not machine-dependent and found that the measurements were comparable between systems (within 3%). in the present study, we analyzed human teeth, in which the degree of mineralization of enamel and dentine are similar among objects. images acquired both at agu and b&h appeared to be comparatively sharp and with few artifacts. olejniczak and grine (2006) reported that the ability of segmentation software to distinguish enamel and dentine differs in some cases from the ability of the fig. 5. scatter plot of pca scores in pc 8 and pc 10 for oes model of ws and ss groups. +3 sd and -3 sd virtual shape models across each axis are indicated at the end of these axes. crown form of maxillary central incisor 8 human eye to detect the same two tissues. in general, data acquisition is performed by one operator under strictly controlled techniques. in addition, laboratory conditions are regulated to minimize inter-operator error. however, assessment of tooth morphology requires a large sample of certain taxa. collections of required sample number may be limited in each laboratory. in particular, isolated teeth with a clear background are difficult to collect. bailey et al. (2004) suggest that clear images with certain prescribed standards can be pooled together. in addition, data that are acquired under proper conditions, even if they were originally scanned for different purposes, can be gathered together and be analyzed as a large sample. in the present study, samples of different origin were combined and scanned under different conditions and techniques. to compensate for inter-system differences, segmentation differences used to distinguish enamel and dentine and the subsequent construction of homologous models were carried out by the first author. nevertheless, an error ranging from 0.5% to 5.5% was revealed from the results of error verification in the present study. in order to compensate for these inter-system errors and account for differences in size, we standardized all the tooth length with the same value. as a result, shape data were standardized with acceptable accuracy (0.0% to 3.5%). these results suggested that tooth models acquired from different systems could be used as valid data after some compensation. at the same time, it must be mentioned that this method is applied to a comparative study and not a measurement field. collective data would benefit a wide range of researchers who engage in dental morphometric assessment (kato and ohno, 2008). the expression of dental traits at the dej junction has been applied to extant and fossil hominoid taxa (skinner et al., 2008, 2010). statistically significant taxon-specific patterns at the dej that are not evident at the oes have also been reported (skinner et al., 2009). furthermore, if dej images can be obtained, the character retains its taxonomic value even in worn teeth. in the present study, we could not find any differences between the dej patterns of human teeth. this result was expected, since analysis for the oes shape should reflect the outcome of observations. sakai and hanamura (1973) describes the small component seen on the lingual surfaces of incisor as follows: “marginal ridges at the dej are less wide than at the oes, while thickness of marginal ridges is mostly the same”. it is presumed that the morphometric differences found by examination of human teeth shape at the dej were too minor to be detected by the statistical analysis. for these reasons, we suggest that the present methodology using oes crown model could be appropriate for objective evaluation. shovel shape is characterized by “a peculiar, pronounced hollow of the lingual surface of the teeth, bounded laterally or surrounded by a well-defined elevated enamel border” (hrdlička, 1920). mizoguchi (1978) reported that the correlation coefficients between the shoveling and marginal ridges are positive and considerably high, ranging from 0.55 to 0.82, in the maxillary central incisor. in the present result of mds analysis on the oes model, the dimension-5 axis showed a shovel-shaped character. virtual shape of +3 sd revealed thick incisal edge, and buccolingual midsection was also thick due to existence of the central ridge. also, it showed narrower and thinner marginal ridges, and consequently a less deep hollow. on the other hand, virtual shape of -3 sd revealed thin incisal edge, and buccolingual midsection was not thick. also, it showed wider and thicker marginal ridges, and consequently a deep hollow. on the other hand, pca resulted in the following pc8 axis: virtual shape with +3 sd showed that the marginal ridges are not prominent, the incisal edge is relatively thick, and consequently a less deep hollow. virtual shape of -3 sd at the pc8 axis revealed that the marginal ridges are prominent, the incisal edge is not thick, and consequently a deep hollow. furthermore, pca resulted in the following pc10 axis: virtual shape of +3 sd showed a wide slope face from lingual cingulum, which was gradually flattening up to the lingual hollow. virtual shape of -3 sd at pc10 revealed no slope from the lingual cingulum. here, as the sample is not large enough, we cannot discuss the influences of mesial and distal marginal ridges with shovel shape. however, it is interesting for pca analysis to extract a factor of the slope from lingual cingulum. as mizoguchi (1978) reported, the central ridges decrease the extent of the shoveling. the present virtual shape showed weak shoveling with the slope face from the lingual cingulum and strong shoveling without the slope. this is interesting in terms of the small component on the lingual surface, which was related to the shoveling shape. also, this component was extracted by pca, not by mds. that is, as kouchi and mochimaru (2006) suggested, mds analysis is efficient for information compression. the present results revealed by mds seemed to be the compressed shape factors compared to the results showed by pca. considering the differences between ws and ss groups combined with the result of calculated virtual forms of +3 sd and -3 sd here, these extracted results coincide with the characteristics of the shovel shape. also, concerning the reason why the first few pcs do not exhibit significant differences between the ws and ss groups, it is attributed to the fact that the individual differences of crown form such as labiolingual width, mesiodistal length, and these mixed elements are relatively larger compared to differences of the shoveling. as figure 5 shows, there are three tooth crowns, #24, #22 and #15, that are apart from each group, and these outliers should be discussed here. first, #24 was located in the area of the ws group, although it was classified as the ss group by observation, probably due to the kato et al. 9 existence of the incline. on the lingual surface of #24, the lingual cingulum had a steep incline to the hollow of the incisal half area. therefore, on observation, the focus was on the deep hollow and prominent lateral ridges and it was judged as having a strong shovel shape, whereas geometric analysis grouped #24 into the ws group based on the presence of the slope. second, #22 was located in the area of the ss group, although it was classified as the ws group on observation. this may be due to the small pit and hollow above the lingual cingulum. it is considered that it was judged as having a weak shovel shape on observation due to less prominent lateral ridges. however, geometric analysis grouped #22 in the strong shovel group based on the presence of the small pit and hollow above the lingual cingulum. finally, in terms of #15, we could see no apparent reason why it was apart from the group; it had a well-developed mesial marginal ridge and strong shoveling. in spite of the deep hollow in the lingual surface, #15 was located in the upper area along with pc8 axis. thus, all factors that influence the results are unknown at this time and require further investigation. objective evaluation of dental morphology has several advantages: 1) it does not involve man-made errors that accompany observation; 2) it enables analysis of data collected from around the world by 3d morphological data; and 3) it enables calculations of average tooth form in a group. there also are disadvantages, including 1) 3d morphological calculation could result in incompatible shape factor with conventional definition of dental traits; and 2) conditions in terms of landmark positioning or geometric algorithm of homologous model may affect the outcome of analysis. nevertheless, potential contributions of these 3d morphometric data to dental science can be expected by overcoming these problems. conclusion the study proposed geometric morphometric analysis of the maxillary central incisor crown form to assess degrees of lingual shoveling. the greatest merit of an objective methodology lies in the fact that a vast amount of data from all over the world could be analyzed all together. although there are many technical challenges to overcome, we conclude that geometric morphometric analysis of micro-ct scanned tooth crowns represents a powerful solution for objective shape assessment of human teeth. acknowledgements we are grateful to paul brown (brown and herbranson imaging, inc.) for providing ct scanned data. tsuneo iida contributed with software programming and image processing. we would like to thank also masahito natsuhara for assistance with micro-ct scanning, and toyohisa tanijiri for creating homologous models. this research was financially supported by the hori information science promotion foundation and aichi-gakuin university. literature cited bailey se, pilbrow vc, wood ba. 2004. interobserver error involved in independent attempts to measure cusp base areas of pan m1s. j anat 205:323-331. bastir m, rosas a, lieberman de, o’higgins p. 2008. middle cranial fossa anatomy and the origin of modern humans. anat rec 292:130-140. borg i, groenen p. 2005. modern multidimensional scaling: theory and applications. 2nd ed. new york: springer. bronstein am, bronstein mm, kimmel r. 2006. generalized multidimensional scaling: a 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australopithecus africanus. j hum evol 56:76-85. skinner mm, evans a, smith t, jernvall j, tafforeau p, kupczik k, olejniczak aj, rosas a, radovčić j, thackeray jf, toussaint m, hublin jj. 2010. brief communication: contributions of enamel-dentine junction shape and enamel deposition to primate molar crown complexity. am j phys anthropol 142:157-163. smith tm, tafforeau p. 2008. new visions of dental tissue research: tooth development, chemistry, and structure. evol anthropol 17:213-226. stefan vh, trinkaus e. 1998. discrete trait and dental morphometric affinities of the tabun 2 mandible. j hum evol 34:443–468. suwa g, kono rt. 2005. a micro-ct based study of linear enamel thickness in the mesial cusp section of human molars: reevaluation of methodology and assessment of within-tooth, serial, and individual variation. anthropol sci 113:273-289. suzuki h. 2005. dental characteristics in the uigur tribe of xinjian-uigur, china: comparative analysis between uigur and other populations. j kyushu dent soc 59:61-79. suzuki m, sakai t. 1966. morphological analysis of the shovel-shaped teeth. anthropol sci 74:202-218 (in japanese). turner cg ii, hanihara k. 1977. additional features of ainu dentition. v. peopling of the pacific. am j phys anthropol 46:13-24. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p 13-31. wickelmaier f. 2003. an introduction to mds. denmark: sound quality research unit, aalborg university. kato et al. 3 dental anthropology 2023 │ volume 36│ issue 01 evaluation of three non-metric traits in maxillary central incisors for population and sex estimations: a cross-sectional study using the turner-scott dental anthropology system jayasankar p. pillai 1,* , girish parmar 1 , rajesh babu 2 , j.m. vyas 2 1 govt. dental college and hospital; ahmedabad, india 2 national forensic sciences university; gandhinagar, india forensic profiling plays an integral part in the human identification process. parameters like age, sex, and ancestry are some of the important components of forensic profiling. the potential unique characteristics or personal information of an individual can also be derived by properly analyzing the dental structures. furthermore, teeth are known to vary morphologically between and within populations and the sexes (scott and turner, 2008). particularly, dental non-metric traits have shown affinities and variations among different population groups (scott and turner, 1997; vargiu et al., 2009). the teeth, thus, can be used to provide an estimate of the ancestry and sex of an unidentified individual. dental non-metric traits show different degrees of expression among different populations (turner, 1991; kelley and larsen, 1991; jernvall and jung, 2000). this grading system places the trait expression into an ordinal scale based on the extent of expression of the traits (turner, 1991). the frequencies of expressions of such traits are used to distinguish the population variations (edgar, 2013; lukacs, 1987). the most commonly studied traits in the tooth are cusp number, cusp size, groove patterns, root length, and number. genetic and environmental influences have also been hypothesized to play an important role in the phenotypic manifestation of dental traits (townsend et al., 2009). for sex estimation, odontometric measures also have proved to be a more reliable method than the tooth morphologic parameters (nagpal et al., 2017). among the non-metric traits, the canine distal accessory ridge has shown a significant sex difference (pilloud and scott, 2020). the unique dental features and the evidence of dental treatments abstract the expressions of non-metric traits are commonly used for population or ancestry estimation. this present study explored the role of dental non-metric data from gujarat state in india for population and sex estimation. the three non-metric traits namely, labial curvature, shoveling, and tuberculum dentale traits in permanent maxillary central incisors in distinct population subgroups from different geographical and community backgrounds were compared. the dental traits in right and left central incisors of 1299 school children, with a mean age of 13.97 years ± 1.70 were examined and recorded using the turner-scott standard dental anthropology plaques. there was no significant difference in the distribution of all three traits between sides. there was a significant difference in the overall distribution of the traits between the different population subgroups (p<0.001). nearly 21% of the overall population was correctly classified district-wise using the non-metric dental traits in the maxillary central incisor. only the shoveling trait showed significant gender differences in the study population. using the discriminant function, 75% of the girls and 29%of the boys were correctly classified. the percentage of correct prediction of sex based on the discriminant function ranged from 57.9% to 70.9% in all the districts. *correspondence to: jayasankar p. pillai govt. dental college and hospital ahmedabad, india email: jppillaigdch@gmail.com keywords: maxillary central incisor, dental anthropology, non-metric dental traits, shoveling, tuberculum dentale, labial curvature, discriminant function analysis 4 dental anthropology 2023 │ volume 36│ issue 01 on teeth have their role in human identification or linking the accused to the victim or the crime. there are instances where the single incisor tooth has been used as an exhibit from the crime scene and sent for forensic odontology investigations like age and sex estimations. though the expressions of non-metric traits have no role in age estimation, they play a significant role in estimating the ancestry and sex of the unidentified decedent. thereby, dental traits help in generating the biological profile of the deceased. according to g. richard scott and christy turner, only a few traits like shovel-shaped incisors, carabelli's cusp, and lower molar cusp number have been characterized on a worldwide scale. however, in some geographic locations like india, dental morphologic traits have not been studied in detail (scott et al., 2018). the application of dental non-metric traits in forensic human identification cases is very limited. however, from research and anthropological points of view, dental traits are being explored to study population variation. such population-based studies in gujarat, a state in the western part of india are also lacking. the principal author (jp), having more than 25 years of experience in teaching dental anatomy and histology in gujarat observed variations in maxillary central incisors of his students who represent different parts of gujarat. in the maxillary central incisor, the labial curvature, shoveling, and tuberculum dentale are the easily identifiable traits. the present population-based study was designed to explore the variations in the expression of these three traits among the eight geographically distinct populations using the standard turner-scott/arizona state university dental anthropology system (asudas). another objective of the study was to explore the variations in these traits between sexes. there is hardly any study examining the expressions of these non-metric traits used for population and sex estimation, especially in this part of india. hence, the present study was conducted to generate the population-based data from eight different districts of gujarat and to explore the differences in the expression between populations and sexes. materials and methods one thousand two hundred and ninety-nine school children from eight different districts of gujarat in the age group of 10 to 17 years were examined from august to november 2019 in their respective schools. the study subjects included 620 (47.7%) boys and 679 (52.3%) girls. the institutional ethical committee's approval was obtained before the start of the study (iec/ gdch/s.2/2019). the necessary permissions from the school authorities of the respective districts were obtained for this study. all the students were residents of gujarat since birth and were basically of gujarati origin in terms of their surname/family name and mother tongue. the clinical evaluation of the children was performed by the principal investigator (jp) using mouth mirrors and probes under good illuminations and the supervision of their respective class teachers. the asudas plaques of three traits in the maxillary central incisors were used as standards (figure 1). the extent of labial curvature, the prominence figure 1. non-metric traits in the permanent maxillary central incisor in the asudas. 5 dental anthropology 2023 │ volume 36│ issue 01 of mesial and distal marginal ridges, and the extent of projection of cingulum on the lingual surface of the maxillary central incisor were the morphological parameters used in the study. there are 5 scores of labial curvature (score 0-4) and 7 scores for grading the expression of shoveling in upper central incisors according to the asudas plaques. for grading tuberculum dentale, there are 4 scores (score 1-4) the grading of the traits were noted in the prescribed proforma and then entered in the microsoft excel sheet. the intra-observer error in grading the traits was tested before the start of the study by the same author (jp) with a subsample of 50 dental students in his institute. statistical analysis the data were analyzed using the statistical package for the social sciences (spss) software (version 23; spss, inc., chicago, usa). the intra-observer error in grading the traits was tested using the cohen’s kappa coefficient of agreement. the descriptive statistics included mean, standard deviation, and frequency distribution in percentages. the wilcoxon signed-rank test was used to test the difference in the expression of the traits between sides. the spearman correlation coefficient was used to correlate the expressions of traits between right and left central incisors. the nonparametric kruskal-wallis was used to test the difference in the expression of the trait among the eight districts' populations. the independent samples mannwhitney u test was used in assessing the graded data between sexes. the discriminant function analysis (dfa) using the traits as independent or predictor variables and the population groups as dependent or grouping variables was carried out using the canonical discriminant function. the prior probabilities were set to compute from group sizes and using the within-group covariance matrix. the level of significance was set at p ≤ 0.05 for all statistical analyses. results sample characteristics the study included a sample of 1299 gujarati school students aged 10 to 17 years from 8 districts of gujarat (figure 2). the mean age of the sample was 13.97 years ± 1.70. the cohen’s kappa coefficient ranged between 0.84 to 0.96 for all the three traits when testing the intra-observer variations in grading the traits in the subsample. this result revealed an almost significant intra-observer agreement in grading the traits (landis and koch, 1977). the frequency distribution of the scores of the three non-metric traits in the overall sample is shown in table 1. the labial surface of incisors was slightly curved and not exactly straight (score 1) in around 82% of the overall cases. the shoveling was absent in 36.5% of the overall sample and 37% of the cases the tuberculum dentale trait was absent and the cingulum was smooth. there was no significant difference in the expression of the traits between right and left central incisors (see table 1). there was also excellent intra-trait correlation between the right and left sides with the spearman correlation coefficient ranging between 0.995 to 0.998. hence, the data of one of the sides (right side), was considered for further analysis. the distribution of the samples according to the scores in all eight districts is shown in table 2. the independent samples kruskal-wallis test revealed a significant difference in the distribution of the scores of all the three traits across the districts (see table 2). the results of the pair-wise comparison of the expression of the traits between the districts are shown in figure 3. this figure shows which of the two districts significantly differ from each other (yellow line) concerning the expression of the traits. among the three traits studied, only the shoveling trait showed a significant difference in its expression between boys and girls. more boys were showing the expression of this trait than girls. (table 3). discriminant function analysis the discriminant function that best separates or discriminates between the groups is reported here. the discriminant function to classify the districtwise population using the dental non-metric traits in maxillary central incisors revealed a canonical correlation of 0.333 with a variance of 69.7%. there was a significant relationship between the discri6 dental anthropology 2023 │ volume 36│ issue 01 figure 2. graph showing the district-wise frequency distribution of the study subjects. traits score right left wilcoxon signed rank test sig.* n % n % maxillary incisor labial curvature ( ui1lc) 0 96 7.4 96 7.4 0.317 1 1068 82.2 1069 82.3 2 127 9.8 126 9.7 3 8 0.6 8 0.6 maxillary incisor shovel shape (ui1ss) 0 471 36.3 467 36.0 0.257 1 550 42.3 555 42.7 2 278 21.4 277 21.3 maxillary incisor tuberculum dentale ( ui1td) 0 488 37.6 487 37.5 0.655 1 719 55.4 720 55.4 2 88 6.8 88 6.8 3 4 0.3 4 0.3 table 1. table showing the frequency distribution of the scores of the three traits in permanent maxillary central incisors on both sides. figure 3. figure showing the results of the pair-wise comparisons of the district populations for all the three traits. the yellow lines show significant difference (adjusted by bonferroni correction) and the black lines represent the insignificant difference between the pairs of districts and the nodes represent the mean rank values, according to the independent kruskal-wallis test. *significant at p<0.05 7 dental anthropology 2023 │ volume 36│ issue 01 table 2. table showing the district-wise distribution of the scores of expressions of the three traits in maxillary central incisors. district code score ui1 lc (rt.) ui1 shoveling (rt.) ui1 tuberculum dentale (rt.) n % n % n % st 0 25 14.0 109 60.9 87 48.6 1 141 78.8 56 31.3 85 47.5 2 13 7.3 14 7.8 6 3.4 3 0 0.00 0 0.0 1 0.6 bo 0 9 6.4 15 10.6 38 27 1 119 84.4 78 55.3 91 64.5 2 13 9.2 48 34 12 8.5 3 0 0.00 0 0 0 0 cu 0 13 8.6 25 16.6 46 30.5 1 102 67.50 69 45.7 93 61.6 2 28 18.50 57 37.7 12 7.9 3 8 5.30 0 0 0 0 gs 0 7 4.80 62 42.8 32 22.1 1 116 80.00 49 33.4 101 69.7 2 22 15.20 34 23.4 12 8.3 3 0 0.00 0 0 0 0 po 0 5 3.80 51 38.6 48 36.4 1 107 81.10 46 34.8 63 47.7 2 20 15.20 35 26.5 19 14.4 3 0 0.00 0 0 2 1.5 bk 0 28 15.30 68 37.2 57 31.1 1 139 76.00 77 42.1 113 61.7 2 16 8.70 38 20.8 13 7.1 3 0 0.00 0 0 0 0 ah 0 8 4.20 59 31.1 81 42.6 1 169 88.90 99 52.1 95 50 2 13 6.80 32 16.8 13 6.8 3 0 0.00 0 0 1 0.5 dg 0 1 0.60 82 46.1 99 55.6 1 175 98.30 76 42.7 78 43.8 2 2 1.10 20 11.2 1 0.6 3 0 0.00 0 0 0 0 chi-square 43.084 135.815 68.400 df. 7 7 7 sig.* 0.000 0.000 0.000 *significant at p<0.05 8 dental anthropology 2023 │ volume 36│ issue 01 minant function and the grouping variables (wilks lambda = 0.843; c2 = 221.293 df=21, p<0.001). the inter-trait correlation revealed a 27.6% correlation between shoveling and tuberculum dentale and a weak correlation between labial curvature and tuberculum dentale (8.1%). between labial curvature and shoveling the correlation was 18.6%. the shoveling trait revealed a maximum discriminating power (94.4%) followed by tuberculum dentale (49.2%) and labial curvature (40.4%). only 21.3% of the overall population was correctly classified using this function. the percentage of correct classification was maximum for the surat district (table 4). the discriminant function for classifying sex based on the variables also revealed a significant relationship between the discriminant function and the grouping variables with a canonical correlation of 0.132. (wilks lambda= 0.983, c2 = 22.764 df=3, p<0.001). the shoveling trait has more discriminant power followed by the tuberculum dentale trait (table 5). the classification statistics revealed 53.2% of the original cases were correctly classified. the percentage of correct classification was more for girls (75.1%) when compared to boys (29.2%). the district-wise results of the discriminant function analysis in sex estimation using the three traits revealed an overall correct classification in the range of 57.9% to 70.9%. however, the function was significant only for three districts (table 6). discussion and conclusions the present study observed the expression of three different non-metric traits in the permanent maxillary central incisors in eight different geographic locations in gujarat. gujarat is a state in western india with a population of nearly 67 million. the population is diverse based on caste, culture, tradition, occupation, geography, etc. the gujarati population in the present study represents the ancestral north indian gene that appears to be much more diverse than other south asian populations (silva et al., 2017). this study is the first of its kind in india which was conducted in a large population using the asudas to discriminate the population subgroups based on the expression of nonmetric traits in the tooth and also on sex estimation. however, as there are possible biases in recording the traits, the estimation of population just based on teeth is difficult and has to be undertaken very cautiously (acharya and sherawat, 2021). in the present study, around 82% of the population had slight curvature (score 1), a trait which is characteristic of asian and asian-derived populations. a study on labial curvature among 20 worldwide populations has shown that moderate curvature was seen in europeans and american indians (nichol et al., 1984). the study also showed that table 3. table showing the frequency distribution of the scores of the three traits in permanent maxillary central incisors in boys and girls. traits score boys (n=620) girls (n=679) mannwhitney u test sig.* n % n % maxillary incisor labial curvature ( ui1lc) 0 41 6.6 55 8.1 0.502 1 514 82.9 554 81.6 2 63 10.2 64 9.4 3 2 0.3 6 0.9 maxillary incisor shovel shape (ui1ss) 0 174 28.1 297 43.7 0.000 1 301 48.5 249 36.7 2 145 23.4 133 19.6 maxillary incisor tuberculum dentale (ui1td) 0 227 36.6 261 38.4 0.171 1 338 54.5 381 56.1 2 51 8.2 37 5.4 3 4 0.6 0 0 9 dental anthropology 2023 │ volume 36│ issue 01 variables unstandardized coefficients standardized coefficients absolute size of correlation constant wilks lambda sig. % of correct classification district % overall % ui lc 0.528 0.229 0.404 -1.839 0.843 0.000 st 58.10 21.30 ui ss 1.179 0.834 0.944 bo 30.50 ui td 0.413 0.244 0.492 cu 21.20 gs 5.50 po 0.00 bk 20.20 ah 0.00 dg 29.80 table 4. the results of the discriminant function analysis performed to discriminate the populations based on the non-metric trait parameters in maxillary central incisors. table 5. the results of the discriminant function analysis performed to discriminate the sex based on the non-metric trait parameters in maxillary central incisors. variables unstandardized coefficients standardized coefficients absolute size of correlation constant centroids wilks lambda sig. % correct classification m f m f overall ui lc -0.285 -0.126 0.094 -0.943 0.139 -0.127 0.983 0.00 29.20 75.10 53.20 ui ss 1.343 0.992 0.990 ui td 0.136 0.082 0.367 table 6. the results of the discriminant function analysis in sex estimation using the traits parameter in all the districts. district eigenvalue canonical correlation wilks lambda chi-square sig. % of correct classification m f overall 1 0.221 0.425 0.819 35.038 0.000 60.5 80.6 70.9 2 0.019 0.135 0.982 2.522 0.471 16.4 93.0 63.1 3 0.030 0.17 0.971 4.304 0.23 74.4 36.2 57.0 4 0.094 0.293 0.914 12.72 0.005 30.2 84.8 64.8 5 0.049 0.216 0.954 6.117 0.106 15.4 93.5 70.5 6 0.012 0.109 0.988 2.160 0.540 75.5 43.5 60.7 7 0.006 0.079 0.994 1.171 0.760 100.0 0.0 57.9 8 0.049 0.216 0.953 8.326 0.040 80.4 30.9 57.90 10 dental anthropology 2023 │ volume 36│ issue 01 labial curvature does not exhibit sexual dimorphism. this finding is similar to the results of the present study. the shoveling trait in the incisors is a characteristic dental feature of north asian and north/south american populations. it is very commonly seen in the native american populations, south east asians, and derived populations like polynesians and micronesians (nichol et al., 1984). grades of shoveling may be observed in both upper and anterior teeth. in the present study, this trait was observed in 64% of the study population. in the tamil population in southern india, the shoveling trait was present in 8% of the population (shrivastav et al., 2018). however, that study did not grade the expression of traits as done in the present study. the same trait in a study on the malayalee population showed a frequency of 6.7% (uthaman et al., 2015). there is a clear-cut genetic demarcation between the kerala population and the gujarati population (d’cuna et al., 2017). however, in another study on the kerala population, the shoveling trait was observed in 69.12% of the population which was similar to the results of the present study (baby et al., 2017). in the bangalore population study, the shoveling of incisors was observed in 65.7% of the population and double shoveling in 66.6%. the shoveling of incisors was noted comparatively lower in the south indian population, while 81% of east indian and 85% of west indian population showed shoveling of incisors (nagaraj et al., 2015). a study by lukacs and pal (2013) demonstrated weak incisal shoveling in the early holocene foragers in the mid-ganga plains in north india. the district-wise comparisons showed a significant difference among all the districts except the chottaudepur district. the expression of tuberculum dentale is more common in upper lateral incisors (20% 50%). the expression of ridge form of tuberculum dentale varies in size and number. there are 7 scores (score 0-6) for grading the expression of tuberculum dentale (edgar, 2017). however, in the asudas, only 4 sores (score 1-4) were considered. the expressions of these three traits significantly differed among the populations. the study populations analyzed in the present study represented different geographical and community backgrounds. the present study also applied dfa to estimate population based on the three traits. the overall per cent of correct classification is only 21.3%. this is because only one tooth (i.e., the central incisor) is being considered here. similar functions using multiple teeth may also be attempted in the future. the present study also applied dfa to estimate sex based on the three variables. among the three traits, shoveling was found to be more powerful in estimating sex and also the population. it was also observed in the present study that the females were more correctly classified than the males. just based on the visual examination of the teeth, it may not be possible to exactly estimate the sex of an individual (radlanski, 2012). sex estimation accuracy rate of 53-65% was earlier reported using the shape analysis of upper arch incisors and canine (horvath et al., 2012). however, odontometric parameters may be useful in some cases. perhaps, a few traits like carabelli’s cusp and canine distal accessory ridge have shown evidence of sexual dimorphism (pilloud and scott, 2020). carabelli’s trait and the molar cusp number traits have shown an accuracy in the range of 70.2%74.8% in sex estimation in children (adler et al., 2012). in the present study, only the permanent maxillary central incisor tooth was considered and its three characteristic traits were used as independent variables to explore their role in population and sex estimations. though there is a potential role of non-metric traits in sex estimation, it needs to be applied very carefully because there is always a possibility of subjective error in grading the traits. this mandates a need for intensive training for handling the standard plaques and identifying the expression grades accurately. in india, the dental curriculum needs to focus on dental anthropological aspects for the undergraduate and postgraduate students, by incorporating practical training on grading the traits using dental models and clinical subjects. such exercise may minimize the interobserver grading errors and increase the scope of application of the non-metric traits in populationbased studies and sex estimation. also, there is a need to incorporate dental morphology details including the non-metric trait details during the recording of the post-mortem dental findings during the dental autopsy procedures. 11 dental anthropology 2023 │ volume 36│ issue 01 acknowledgments the principal author wishes to acknowledge the department of health and family welfare, govt. of gujarat for the permission to carry out the project. the author also acknowledges the support of the district health authorities, the district education departments, the schools' management, and the dental surgeons posted in the district hospitals of all eight districts. the author extends his gratitude to all the school students who participated in the project as study subjects. references acharya, a. b., & sehrawat, j. s. (2021). morphological dental trait examination of ajnala skeletal remains and their possible population affinity. journal of forensic odontostomatology, 39(1), 24. adler, c. j., & donlon, d. (2010). sexual dimorphism in deciduous crown traits of a european-derived australian sample. forensic science international, 199(1-3), 29-37. baby, t. k., sunil, s., & babu, s. s. (2017). nonmetric traits of permanent posterior teeth in kerala population: a forensic overview. journal of oral and maxillofacial pathology: jomfp, 21 (2), 301. d’cunha, a., pandit, l., & malli, c. (2017). genetic variations in the dravidian population of south west coast of india: implications in designing case-control studies. the indian journal of medical research, 145(6), 753. edgar, h. j. h. (2013). estimation of ancestry using dental morphological characteristics. journal of forensic sciences, 58, s3-s8. edgar, h. j. h. (2017). dental morphology: an illustrated manual. new york: routledge. horvath, s. d. (2012). the correlation between anterior tooth form and gender–a 3d analysis in humans. the european journal of esthetic dentistry, 7(3):334-343. irish, j. d., & nelson, g. c. (eds.). (2008). technique and application in dental anthropology. cambridge university press: cambridge, uk. jernvall, j., & jung, h. s. (2000). genotype, phenotype, and developmental biology of molar tooth characters. american journal of physical anthropology, 113(s31), 171-190. kelley, m. a., & larsen, c. s. (eds.). (1991). advances in dental anthropology. new york: wiley-liss. landis, j. r., & koch, g. g. (1977). the measurement of observer agreement for categorical data. biometrics, 33, 159-174. lukacs, j. r. (1987). biological relationships derived from morphology of permanent teeth: recent evidence from prehistoric india. anthropologischer anzeiger, 45(2), 97–116. lukacs, j. r., & pal, j. n. (2013). dental morphology of early holocene foragers of north india: non-metric trait frequencies and biological affinities. homo, 64(6), 411-436. nagaraj, t., sherashiya, p. a., hemavathy, s., yogesh, t. l., goswami, r. d., & sreelakshmi, n. (2015). regional variation in incisor shoveling in indian population. journal of advanced clinical and research insights, 2(5), 193-196. nagpal, b., sreeshyla, h. s., & yadav, m. (2017). reliability of odontometric variations as an important aid in gender determination. indian internet journal of forensic medicine & toxicology,15(4), 76-81. nichol, c. r., turner, c. g., & dahlberg, a. a. (1984). variation in the convexity of the human maxillary incisor labial surface. american journal of physical anthropology, 63(4), 361-370. pilloud, m. a., & scott, g. r. (2020). dentition in the estimation of sex. in: a. r. klales (ed.). sex estimation of the human skeleton (pp.149169). san diego, ca: academic press. radlanski, r. j., renz, h., & hopfenmüller, w. (2012). sexual dimorphism in teeth? clinical relevance. clinical oral investigations, 16(2), 395-399. scott, g. r., & turner, c. g. (1997). anthropology of modern human teeth. cambridge: cambridge university press. scott, g. r., turner, c. g., townsend, g. c., & martinón-torres, m. (2018). the anthropology of modern human teeth: dental morphology and its 12 dental anthropology 2023 │ volume 36│ issue 01 variation in recent and fossil homo sapiens. cambridge, uk: cambridge university press. silva, m., oliveira, m., vieira, d., brandão, a., rito, t., pereira, j. b., ... & soares, p. (2017). a genetic chronology for the indian subcontinent points to heavily sex-biased dispersals. bmc evolutionary biology, 17(1), 1-18. srivastav, m., bharanidharan, r., ramya, r., dineshkumar, t., kumar, a. n., & kumar, a. r. (2018). evaluation of dental non-metric traits in ethnic tamil population: an aid in forensic profiling. journal of clinical & diagnostic research, 12(10) hc01-3. townsend, g., hughes, t., luciano, m., bockmann, m., & brook, a. (2009). genetic and environmental influences on human dental variation: a critical evaluation of studies involving twins. archives of oral biology, 54, s45-s51. turner, c. g., nichol, c. r., & scott, g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in m. a. kelley & c. s. larsen (eds.), advances in dental anthropology (pp.13-31). new york: wiley liss. uthaman, c., sequeira, p. s., & jain, j. (2015). ethnic variation of selected dental traits in coorg. journal of forensic dental sciences, 7(3), 180. vargiu, r., cucina, a., & coppa, a. ( 2009 ). italian populations during the copper age: assessment of biological affinities through morphological dental traits. human biology, 81, 479 – 493. stojanowski et al. 2013.2 7 geographic patterns of early holocene new world dental morphological variation christopher m. stojanowski 1 , kent m. johnson 1 , william n. duncan 2 1 center for bioarchaeological research, school of human evolution and social change, arizona state university, tempe, az 85287 2 department of sociology and anthropology, east tennessee state university, johnson city, tn 37614-1702 abstract dental anthropology played a seminal role in early studies of the peopling of the new world, and was a foundation of the early three wave model proposed by greenberg, turner and zegura. in recent years, however, developments in anthropological genetics, craniometry, and archaeological discoveries have largely omitted dental anthropology from debates regarding native american origins. here we consider this situation and reassert dental anthropology’s relevance to the topic by presenting an interindividual analysis of paleoindian and paleoamerican dentitions. a small set of dental morphological variables was used to estimate gower similarity coefficients between individual specimens. the resulting similarity matrix was ordinated using multidimensional scaling; all analyses were performed in clustan v. 7.05. while results should be considered preliminary, patterns of variation suggest morphological similarity along both coasts of north and south america with a somewhat distinct grouping of north american paleoindians deriving from more inland portions of the continent. this pattern is consistent with recent genetic scenarios, notably the bicoastal model presented by o’rourke and raff (2010), which indicates that paleoindians may have taken multiple migration routes from beringia, moving along both coasts as well as through the ice free corridor. future studies may build on this work to reintegrate dental data and analysis into research concerning the peopling of the new world. keywords: new world, dental morphology, paleoindian, paleoamerican dental morphology played a key role in the development of the tripartite model of new world population origins (greenberg et al., 1985, 1986; turner, 1971, 1983, 1984, 1985a, b, 1986). while this model still provides a viable explanation for the settlement of the western hemisphere (estradamena et al., 2010; reich et al., 2012), recent advances in anthropological genetic sampling protocols, amplification techniques, and analytical approaches have provided more nuanced understandings of new world population structure. these include models that propose a single origin from an asian source population isolated in beringia prior to colonization of the americas (estrada-mena et al., 2010; fagundes et al., 2008; kitchen et al., 2008; mulligan et al., 2008; schroeder et al., 2007, 2009; tamm et al., 2007; wang et al., 2007), dual origin models (gilbert et al., 2008; rasmussen et al., 2010), and more complex scenarios involving one or more migrations from a heterogeneous source population – possibly via different migration routes – followed by bidirectional gene flow between asia and the americas that lasted several thousand years (gonzález-josé and bortolini, 2011; kumar et al., 2011; mazières, 2011; o’rourke and raff, 2010; perego et al., 2009, 2010; ray et al., 2010; rubicz et al., 2010; tamm et al., 2007). in addition, recent archaeological discoveries have largely supplanted the “clovis first” model which dominated paleoindian research for several decades (e.g., adovasio and pedler, 2004; dillehay, 1997; goebel et al., 2008; waters et al., 2011) and which coincided strongly with the predictions of the tripartite model. discoveries of early holocene skeletal material from south america, combined with advances in phenotypic data analysis better grounded in evolutionary processes, have also generated new views on the peopling of the americas (e.g., de azevedo et al., 2011; gonzalez et al., 2010; gonzález-josé and bortolini, 2011; gonzálezcorrespondence to: christopher m. stojanowski 900 s. cady mall school of human evolution and social change arizona state university tempe, az 85287 cstojano@asu.edu 8 josé et al., 2001, 2008; mena l. et al., 2003; neves et al., 2004, 2005; perez et al., 2007, 2009; pucciarelli et al., 2003, 2006, 2008, 2010). despite the historical importance of dental anthropology in the first americans debate, recent synthetic surveys of the literature (e.g., dillehay, 2009; fiedel, 2004; goebel et al., 2008; gonzálezjosé and bortolini, 2011; mazières, 2011; o’rourke, 2011; o’rourke and raff, 2010; pitblado, 2011) indicate that dentition has lost its relevance in these discussions. in fact, the most recent literature review fails to include a single citation for papers using dental morphology as a basis for inferring new world population history (pitblado, 2011). there are many reasons why this may be. however, one inescapable fact is that genetic, archaeological, and craniometric specialists have adopted new research approaches and methods over the last decade, including more sophisticated types of data capture and analysis, which increase the specificity and nuance of their interpretations. this is evidenced by the incorporation of inferential analyses that access more complex evolutionary models in the analysis of phenotypic size and shape. dental anthropology on the other hand has largely maintained a focus on population-based frequency analyses and, in particular, the sinodont/sundadont dichotomy (see turner, 1990). our purpose here is not to engage existing debates about the utility of the sinodont/sundadont model or the relationship between specific paleoindian or paleoamerican specimens and the morphological complex associated with sinodonty or sundadonty (e.g., chatters, 2000; haydenblit, 1996; lahr and haydenblit, 1995; powell, 1993, 1995, 2005; sutter, 1997, 2005; turner, 2002). here, we adopt a more paleontological focus that recognizes the relative dearth of existing early holocene material from north and south america and the singleton status of much of the north america paleoindian record. our primary goal in this paper is to move the field forward by demonstrating that fragmentary specimens and small data sets can be used to consider hypotheses about the temporal and spatial structure of new world phenotypic variation using a research approach distinct from frequency-based assessments. we make no claims that one approach is necessarily better than the other. we only demonstrate the potential of different approaches for complementing one another and engaging new models of interpretation that add nuance to the literature. materials and methods using existing morphological data, our purpose in this paper is to determine whether early holocene (paleoindian and paleoamerican) interindividual dental morphological variation is geographically structured. that is, we consider whether inter-individual patterns of affinity reproduce geographic spatial structure, and if so, whether dental variation corresponds with recent hypothesized migration scenarios into the new world, such as the bi-coastal model proposed by o’rourke and raff (2010), which accommodates multiple, possibly contemporaneous migration routes from beringia through the ice-free corridor and along both coasts. we mined published raw dental morphological data from confirmed paleoindian and paleoamerican dentitions (see chatters, 2000; jenks, 1937; owsley et al., 2010; potter et al., 2011; powell and rose, 1999; turner, 1992; young, 1988) and verified the early holocene age of these specimens (> 7500bp). these data are summarized in table 1. raw trait scores were used to generate inter-individual similarity statistics using clustan v. 7.05 (wishart, 2004). gower coefficients were used because they allow for missing data (obviating data imputation) and mixed scale data types (ordinal and binary). similarities were ordinated and visualized using multidimensional scaling in two dimensions set at 500 runs and iterations. variables were removed from the final analysis based on frequency of observation (variables that were too sparse were removed) and if the variable demonstrated insufficient trait score variability among individuals. those variables that demonstrated no inter-individual variation or were autapomorphic were removed from the raw dataset prior to the calculation of similarities. in addition, traits that were clearly redundant (for example, carabelli’s scores for maxillary m1s and m2s) were reduced, where the trait that was kept was largely decided based upon data density rather than notions of key tooth representation. individual paleoindian or paleoamerican dentitions were omitted if they preserved too few recorded scores, although we note the rarity of north american specimens required more consideration of trait exclusion to maximize the coverage of the 9 t a b l e 1 . e a rl y s k e le ta l re m a in s fr o m n o rt h a n d s o u th a m e ri c a a s a m p le /s it e a g e ( 1 4 c y e a rs b p ) n n o rt h a m e ri c a n s k e le ta l re m a in s in c lu d e d i n t h e p re se n t a n a ly si s w a rm m in e ra l s p ri n g s, f l 1 0 2 6 0 + / 1 9 0 1 a rc h l a k e , n m 1 0 2 2 0 + / 5 0 ; 8 8 7 0 + / 4 0 1 h o rn s h e lt e r, t x 9 8 7 5 + / 1 1 0 ( a v e ra g e ) 2 g o rd o n c re e k , c o 9 4 5 5 + / 1 1 0 ( a v e ra g e ) 1 t e h u a c á n v a ll e y ( t c 5 0 ), m e x ic o c a . 8 5 0 0 -7 0 0 0 1 k e n n e w ic k , w a 8 4 1 0 + / 6 0 ( a v e ra g e ) 1 p e li c a n r a p id s, m n 7 8 4 0 + / 7 0 1 a d d it io n a l n o rt h a m e ri c a n s k e le ta l re m a in s n o t in c lu d e d i n t h e p re s e n t a n a ly s is u p w a rd s u n r iv e r, a k ~ 1 1 5 0 0 1 a rl in g to n s p ri n g s, c a 1 0 9 6 0 + / 1 1 0 ; 1 0 0 8 0 + / 8 1 0 ; 1 0 0 0 0 + / 3 1 0 1 p e ñ ó n w o m a n i ii , m e x ic o 1 0 7 5 5 + /7 5 1 a n z ic k , m t 1 0 6 8 0 + / 5 0 ( a v e ra g e ) 2 b u h l, i d 1 0 6 7 5 + / 9 5 1 w il so n -l e o n a rd , t x 1 0 5 0 0 -1 0 ,0 0 0 1 c h im a lh u a c á n , m e x ic o c a . 1 0 5 0 0 1 m o st in , c a 1 0 4 7 0 + /4 9 0 1 t la p a c o y a i , m e x ic o 1 0 2 0 0 + /6 5 1 m a rm e s, w a 1 0 1 3 0 + / 3 0 0 ; 9 8 4 0 + /3 0 0 ; 9 8 2 0 + /3 0 0 3 m id la n d , t x c a . 1 0 0 0 0 1 w h it e w a te r d ra w , a z 1 0 0 0 0 -8 0 0 0 1 j .c . p u tn a m , t x -b 1 4 9 -p e t -4 0 8 ( o n y o u r k n e e s c a v e ), a k 9 7 3 0 + / 4 0 ( a v e ra g e ) 1 g ri m e s p o in t b u ri a l s h e lt e r, n v 9 4 7 0 + /6 0 1 s p ir it c a v e , n v 9 4 1 5 + / 2 5 ( a v e ra g e ) 1 w iz a rd ’s b e a c h , n v 9 2 2 5 + / 6 0 ( a v e ra g e ) 1 b ro w n s v a ll e y , m n 9 0 4 9 -8 7 9 0 + / 1 1 0 /8 2 1 l a b re a , c a 9 0 0 0 + / 8 0 1 m e tr o b a ld e ra s, m e x ic o c a . 9 0 0 0 1 c u e v a d e t e c o lo te , m e x ic o c a . 9 0 0 0 -7 0 0 0 1 k o st e r (h o ri z o n 1 1 ), i l c a . 8 5 0 0 9 r e n ie r, w i c a . 8 5 0 0 -6 0 0 0 1 c 10 t a b l e 1 ., c o n t’ d f is h b o n e c a v e , n v 8 3 7 0 + / 5 0 ; 8 2 2 0 + / 5 0 1 l a j o ll a , c a 8 3 5 0 + /9 0 2 g o re c re e k , b c 8 2 5 0 + / 1 1 5 1 h o u rg la ss c a v e , c o 8 1 7 0 + /1 0 0 ; 7 9 4 4 + /8 4 ; 7 7 1 4 + /7 7 1 s ti c k m a n , w a 8 1 2 5 + /5 0 ( a v e ra g e ) 1 w in d o v e r, f l 8 1 2 0 -6 9 9 0 1 6 8 l ’a n se a m o u r, l a b ra d o r 7 5 3 0 + /1 4 0 1 t e x c a l c a v e , m e x ic o 7 4 8 0 + /5 5 1 s h if ti n g s a n d s, t x 1 s o u th a m e ri c a n s k e le ta l re m a in s in c lu d e d i n t h e p re se n t a n a ly si s c e rc a g ra n d e 6 a n d 7 , l a g o a s a n ta , b ra z il c a . 1 1 0 0 0 -8 0 0 0 4 4 c u c h ip u y , c h il e 8 0 7 0 -6 1 0 5 ; c a . 8 0 0 0 -6 0 0 0 3 a d d it io n a l s o u th a m e ri c a n s k e le ta l re m a in s n o t in c lu d e d i n t h e p re se n t a n a ly si s l a p a v e rm e lh a i v ( l u z ia ), b ra z il 1 1 6 8 0 + /5 0 0 – 1 0 2 0 0 + /2 2 0 ; 9 3 3 0 + /6 0 ( m in im u m a g e ) 1 p a m p a d e f o si le s 1 3 , p e ru 1 0 2 5 0 + /1 8 0 2 s u e v a 1 , c o lo m b ia 1 0 0 9 0 + /9 0 1 q u iq c h e c a v e t o m b 1 , p e ru 9 9 4 0 + /2 0 0 d 1 t o c a d o s c o q u e ir o s, b ra z il 9 8 7 0 + /5 0 1 t e q u e n d a m a , c o lo m b ia 9 7 4 0 + /1 3 5 9 t o c a d a j a n e la d a b a rr a d o a n to n ia o , b ra z il 9 6 7 0 + /1 4 0 1 s a n ta n a d o r ia c h o b u ri a l x ii , b ra z il 9 4 6 0 + /1 1 0 1 g u a v io 1 , c o lo m b ia 9 3 6 0 + /4 5 1 p iu q u e n e s c a v e , c h il e 8 9 9 0 + /4 0 3 a c h a -2 a n d a c h a -3 , c h il e 8 9 7 0 + /2 5 5 5 b a ñ o n u e v o -1 c a v e , c h il e 8 8 9 0 + /9 0 ; 8 8 8 0 + /5 0 ; 8 8 5 0 + /5 0 5 c a p e li n h a b u ri a l ii ( l u z io ), b ra z il 8 8 6 0 + /6 0 1 s a n to d o m in g o t o m b 1 , p e ru 8 8 3 0 + /1 9 0 1 p a li a ik e , c h il e c a . 8 8 0 0 4 s a n ta n a d o r ia c h o , b ra z il 8 2 8 0 + /4 0 ; 8 1 8 5 + /1 1 0 4 0 l a s v e g a s, e c u a d o r 8 2 5 0 -6 6 0 0 1 9 2 h u e n te la u q u é n -2 , c h il e 8 0 8 0 + /7 0 1 in ti h a u si , a rg e n ti n a 8 0 6 0 + /1 0 0 ; 7 9 7 0 + /1 0 0 6 11 fig. 1. map of north and south american showing the location of paleoindian and paleoamerican specimens used in this analysis: 1. arch lake; 2. gordon creek; 3. horn shelter no. 2; 4. kennewick; 5. pelican rapids; 6. tehuacán (tc502); 7. warm mineral springs; 8. cuchipuy; 9. lagoa santa. fig. 2. multidimensional scaling of gower similarity coefficients calculated from eight dental morphological traits for confirmed north american paleoindians. icons represent geographic divisions: circle = western north america (kennewick), square = central north america, diamond = eastern north america (warm mineral springs). t re s v e n ta n a s t o m b 1 , p e ru 8 0 3 0 + /1 3 0 1 s u m id o u ro c a v e , l a g o a s a n ta , b ra z il > 8 0 0 0 2 9 m o n te h e rm o so 1 -2 , a rg e n ti n a 7 8 6 6 + /7 5 1 a rr o y o s e c o , a rg e n ti n a 7 8 0 5 + /8 5 – 7 5 8 0 + /5 0 5 c h e c u a , c o lo m b ia 7 8 0 0 + /6 0 – 6 8 0 0 + /4 0 4 s a n to d o m in g o t o m b 2 , p e ru 7 7 4 0 + /8 5 1 a r e fe re n c e s fo r e a rl y a m e ri c a n s k e le ta l re m a in s a re l is te d i n s to ja n o w sk i e t a l. ( 2 0 1 3 ). b a ss o c ia te d w it h s tr a tu m t h o u g h t to d a te t o t h e l a te p le is to c e n e ( y o u n g 1 9 8 8 ). c t h e s m a ll q u a n ti ty o f c a lc in e d b o n e f ra g m e n ts i s su g g e st iv e o f a s in g le i n d iv id u a l (m a so n a n d i rw in 1 9 6 0 ). d d a te i s fr o m t h e l e v e l u n d e rl y in g t h e s k e le ta l re m a in s. t a b l e 1 ., c o n t’ d 12 terning. for example, the four central north american samples (non-coastal) form a weak cluster in the upper right quadrant while both coastal samples plot in the negative half of both axes. this could be consistent with a single population bifurcating and migrating quickly down the atlantic and pacific coasts of north america with a distinct population colonizing the middle of the continent. inclusion of south american paleoamerican dentitions required using only six maxillary traits (ui1 shoveling, um1 hypocone, um1 carabelli, um1 enamel extension, up1 root number, and um2 root number). the sample included the same paleoindian specimens as above (with the exception of kennewick which had to be excluded), a single individual from mexico (tehuacán tc50-2), two individuals from western south america (cuchipuy), and seven individuals from eastern south america (lagoa santa). results are presented in figure 3. although the clustering tendency was more abstract there does appear to be some geographic patterning evident in this figure. for example, the dentitions from western south america, eastern south america, mexico, and eastern north america dominate the positive half of the dimension two axis, while dentitions from noncoastal north american paleoindians dominate the negative half of the dimension two axis. another way to consider this is that coastal samples from both north and south america cluster in the positive half of the dimension two axis while interior samples (all from north america) plot in the negative half of the dimension two axis. remarkably, the overall pattern of variation does not change with the addition of south american data. these analyses, therefore, may reflect a possible bi-coastal migration of early holocene populations along both the pacific and atlantic coasts of north and south america with a somewhat distinct population inhabiting the interior of north america (perhaps involving the ice-free corridor), consistent with o’rourke and raff’s (2010) model. conclusion recent advances in archaeology, anthropological genetics, and human craniometry have enhanced our understanding of new world population origins and migration dynamics within fig. 3. multidimensional scaling of gower similarity coefficients calculated from six maxillary dental morphological traits for confirmed north and south american paleoindians and paleoamericans. icons represent geographic divisions: circle = mexico, diamond = eastern north america, square = central north america, upward triangle = eastern south america, downward triangle = western south america. continent so that assessments of geographic structure were possible. results because the majority of south american dentitions lacked paired maxillae and mandibles we first consider patterns of inter-individual variation among north american paleoindian specimens. despite the number of possible paleoindian specimens (see table 1) we were only able to include data from six individuals: pelican rapids, gordon creek, warm mineral springs, arch lake, horn shelter 2, and kennewick. these six dentitions range from washington to florida with most samples deriving from the middle of the continent (figure 1). based on data preservation, we included eight dental morphological traits in the calculation of gower similarity coefficients (ui1 shoveling, um1 hypocone, um1 carabelli, um1 enamel extension, up1 root number, um2 root number, lm2 cusp number, and lm2 root number). results of the multidimensional scaling are presented in figure 2. there is some evidence for geographic pat 13 the western hemisphere. for a variety of reasons, dentition has figured less prominently in recent first american debates to the point that the most recent literature review of this expansive literature ignores dentition entirely (pitblado, 2011). this is unfortunate. here we have tried to demonstrate that a specimen-specific approach to paleoindian and paleoamerican dental morphology may have some merit. in particular, using a small series of dentitions and morphological traits our results suggest a similar dental phenotype among coastal populations of the early holocene new world with a somewhat distinct morphology among central, non-coastal north american dentitions. here, we have emphasized population structure and evolution as the primary explanatory mechanism; however, differential selection pressures related to distinct coastal/inland diets should also be considered. in closing, we want to stress how preliminary these results are. as indicated in table 1 there is now an 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and siberia: bioarchaeological evidence for the colo nization of the new world. in: jablonski n, edi tor. the first americans: the pleistocene colon ization of the new world. san francisco: california academy of sciences. p 123-158. wang s, lewis cm jr., jakobsson m, et al. 2007. genetic variation and population structure in native americans. plos genetics 3:2049-2067. waters mr, forman sl, jennings ta, et al. 2011. the buttermilk creek complex and the origins of clovis at the debra l. friedkin site, texas. science 311:1599-1603. wishart d. 2004. clustan graphics primer. mid dlesex: allstar services. young de. 1988. the double burial at horn shel ter: an osteological analysis. central texas archaeologist 11:13-115. holt et al. 2012.1 4 brief communication: premolar enamel formation: completion of figures for aging leh defects in permanent dentition sarah a. holt 1* , donald j. reid 2 , and debbie guatelli-steinberg 1 1department of anthropology, the ohio state university, columbus, oh 43210, usa 2department of oral biology, school of dental sciences, university of newcastle upon tyne, framlington place, newcastle upon tyne ne2 4bw, uk key words: cross striations; striae of retzius; enamel formation; tooth growth; dental development variation in enamel formation provides many avenues of inquiry for those interested in comparisons of developmental life histories and aging enamel defects. for example, assessing the age of formation of linear enamel hypoplasias provides one line of evidence to estimate rates of childhood morbidity (e.g., goodman and song, 1998). due to the nonlinear nature of enamel growth, linear regression formulas utilizing total crown height cannot be used to accurately estimate age of leh formation (reid and dean, 2000; martin et al., 2008; ritzman et al., 2008). data on population specific variation in crown formation times based on percentages of total growth are therefore of great use for accurately estimating leh formation times. the reid and dean (2006) methodology for histological growth assessment reflects the variability of enamel growth rates along the length of the crown and incorporates standard deviations reflecting inter-individual variation, avoiding the problem of applying linear statistical models to a nonlinear growth pattern. studies completed using other methods, including dental radiographs of living children, suggested high levels of variation in crown formation time among human populations (e.g., tompkins, 1996). the implication is that new research on leh formation times conducted without the histological growth assessment method should draw on crown formation timing data specific to the population being studied (reid and dean, 2000; reid et al., 2006; martin et al., 2008). however, recent work in which incremental growth is assessed histologically has shown the anterior teeth and molars to be less variable between populations than previously reported (reid and dean, 2006). reid and dean first published research comparing enamel formation times in populations from northern europe (2000, 2006) and southern africa (2006) that included tables presenting age in days for enamel formation at the completion of each decile of crown height for anterior teeth and molars (2006: 334-35). figures depicting these data provided a visual guide for estimating leh (2006: 343-44). these figures include an estimated age at mineralization based on previous histological studies (reid et al., 1998; reid and dean, 2000; antoine, 2001; dean and reid, 2001) but the authors note these initiation times are highly variable, as much as a full year in the m3 (reid and dean, 2006). a follow-up study (reid et al., 2008) presented premolar data from these same populations, but did not provide charts of growth by decile of crown height or figures including initiation estimations. abstract variation in enamel formation has become increasingly important in comparative studies of dental development. previously published work on the development of human enamel in groups from southern africa and northern europe has allowed for more accurate estimation of formation timing of linear enamel hypoplasias. currently, although data for all tooth types has been published, charts of enamel growth by decile useful in this type of estimation have been limited to molars and anterior teeth. this paper completes this series with a table and figure of mean formation times of human premolars for each decile of crown development using previously published histological data of daily enamel growth. *correspondence to: sarah holt, department of anthropology, the ohio state university 4034 smith laboratory. 174 w. 18th ave. columbus, ohio 43210 usa email: holt.249@osu.edu tel: (614)330-6930 5 table 1. age (in days) for enamel formation at each decile of crown height for molar teeth in each sample, +/-1 standard deviation southern african premolar tooth crown formation times northern european crown formation times lp3 n=33 lp4 n=28 up3 n=45 up4 n=41 initiation 675 967 675 967 cusp completion 902 +/27 1234 +/32 910 +/36 1211 +/42 10% complete 943 +/29 1270 +/34 949 +/36 1250 +/42 20% complete 995 +/33 1310 +/38 993 +/34 1292 +/42 30% complete 1053 +/37 1356 +/48 1039 +/34 1335 +/42 40% complete 1116 +/48 1408 +/53 1092 +/37 1382 +/46 50% complete 1187 +/61 1472 +/60 1157 +/44 1444 +/46 60%complete 1266 +/75 1548 +/74 1239 +/52 1526 +/50 70% complete 1356 +/92 1638 +/92 1336 +/55 1627 +/58 80% complete 1452 +/109 1741 +/110 1443 +/62 1737 +/70 90% complete 1558 +/124 1869 +/117 1570 +/71 1854 +/77 crown completion 1665 +/141 1986 +/124 1703 +/76 1974 +/82 lp3 n=33 lp4 n=22 up3 n=34 up4 n=44 initiation 675 967 675 967 cusp completion 891 +/-44 1231 +/-36 952 +/-65 1225 +/-63 10% complete 952 +/-54 1276 +/-41 1010 +/-61 1284 +/-52 20% complete 1018 +/-68 1328 +/-43 1068 +/-52 1338 +/-48 30% complete 1088 +/-80 1381 +/-52 1132 +/-50 1390 +/-44 40% complete 1164 +/-96 1441 +/-65 1203 +/-49 1448 +/-48 50% complete 1256 +/-113 1509 +/-76 1285 +/-53 1521 +/-52 60%complete 1359 +/-135 1594 +/-84 1389 +/-60 1613 +/-62 70% complete 1481 +/-164 1697 +/-98 1518 +/-66 1724 +/-71 80% complete 1614 +/-194 1817 +/-122 1663 +/-78 1856 +/-85 90% complete 1766 +/-224 1948 +/-143 1838 +/-84 1998 +/-98 crown completion 1908 +/-253 2071 +/-162 2011 +/-92 2134 +/-110 currently, therefore, although enamel growth patterns of these populations have been established, the series of charts and figures providing a visual guide for estimating population specific leh formation times has lacked the published information on premolars. this communication completes the publication of this series of figures by presenting premolar enamel growth by decile for populations from southern africa and northern europe (table 1, fig. 1). materials and methods data from 147 premolars collected from two populations, southern africa and newcastle, england, (northern europe), were used to create tables of enamel formation (reid et al., 2008). the premolars were originally collected after extraction during oral surgery and histological thin sections were prepared for polarized light microscopy (reid and dean, 2006). individual periodicity for each tooth was established by counting daily cross-striations in enamel, and formation times for each decile of crown height was then recorded using measurements of long-period striations corresponding to the perikymata on the external crown surface. initiation ages of crown mineralization for both samples were estimated from a third, french sample (reid et al., 1998). by adding these decile data to age at initiation of crown mineralization, formation times for both cuspal and lateral enamel formation in days was determined (see reid et al., 2008 and reid and dean, 1998 for full discussion of methodology). 6 although extremely preliminary research by one of the authors on mineralization initiation times specific to these populations supports the current expectation that mineralization timing will vary, conclusive data from large scale studies remains unavailable. given the absence of data, the significance of future publications in this area on the chart presented here would be speculative, however, the authors intend to update the available charts as new data are available. discussion although total crown formation time was found to be significantly different between the populations (p<0.00) (see reid et al., 2008 for full discussion of statistical methods), as with the anterior and molar teeth, premolar formation time between populations is more similar than radiographic studies once suggested (e.g., tompkins, 1996). while the southern african sample crowns formed consistently more quickly, the means of both samples range only from 0.3 years difference in the lower p4 to 0.8 years difference in the upper p3. thus, the small amount of variation may not be particularly meaningful in comparisons of human populations (reid and dean, 2006; martin et al., 2008). because this method presents formation time by decile, the estimation of age during leh formation can be independent from any variation in length of the crown. this more accurate method has already been widely used for the anterior teeth and molars (e.g., reid and dean, 2000; 2006). the addition of premolar data will allow for comparisons of leh within the dentition of individuals, specifically to match leh manifestations of a single stress event across premolars and other teeth within an individual. despite the fact that enamel growth is not linear, martin et al. (2008) found no difference between a linear and nonlinear interpolation for ages that fall between the established deciles. they conclude that a linear interpolation is sufficient to age defects that fall within a decile. while we await further histological data from other populations, the charts presented here (table 1, fig. 1) make it possible to provide estimates of leh formation times that utilize the population specific information currently available from two geographically distant populations. conclusion recent studies applying histological methods to establish enamel formation timing have shown less variation in modern human premolar formation between populations than previous methodologies; however, statistically significant differences have been documented between a large sample of northern european and southern african individuals (reid and dean, 1998; reid et al., 2008). previously published data on histological timing of each decile of premolar tooth crowns can be used to estimate timing of leh formation without destructive histological sectioning. this paper presents a summary of the previously published data on crown formation variation and presents a graphic diagram of the premolar formation times by decile drawn from histological analysis (table 1, fig. 1). in addition to providing previously unpublished data on the mineralization initiation estimates used to create these decile formation charts, it is the hope of the authors that including a visual representation of premolar crown formation by decile to the existing charts for other tooth types will allow for more practical application of the known formation timing to analysis of the external enamel of premolars. fig. 1. mean estimates for the chronological ages of enamel formation in premolars for each decile of crown length rounded up or down to 0.1 year for the southern african sample vs. the northern european sample. both initiation and cuspal enamel formation are included in these estimates. 7 literature cited antoine, d. 2001. evaluating the periodicity of incremental structures in dental enamel as a means of studying growth in children from past populations. ph.d. dissertation, university of london. dean, mc, reid, dj. 2001. perikymata spacing and distribution on hominid anterior teeth. am j phys anthropol 116:209-215. goodman ah, song rj. 1998. sources of variation in estimated ages at formation of linear enamel hypoplasias. in: hoppa rd, fitzgerald cm, editors. human growth in the past: studies from bones and teeth. cambridge: cambridge university press 210–240. martin sa, guatelli-steinberg d, sciulli pw, walker pl. 2008. brief communication: comparison of methods for estimating chronological age at linear enamel formation on anterior dentition. am j phys anthropol 135:362-265. reid dj, beynon ad, rameriez rozzi fv. 1998. histological reconstruction of dental development in four individuals from a medieval site in picardie, france. j hum evol 35:463–477. reid dj, dean mc. 2000. brief communication: the timing of linear hypoplasias on human anterior teeth. am j phys anthropol 113:135–139. reid dj, dean mc. 2006. variation in modern human enamel formation times. j hum evol 50:329–346. reid dj, guatelli-steinberg d, walton p. 2008. variation in modern human premolar enamel formation times: implications for neandertals. j hum evol 54:225-235. ritzman tb, baker bj, schwartz gt. 2008. a fine line: a comparison of methods for estimating ages of linear enamel hypoplasia formation. am j phys anthropol 135:348–361. tompkins, rl, 1996. human population variability in relative dental development. am j phys anthropol 99:79-102. huffman and antoine 2010.1 67 dental cementum is calcified tissue that covers the dentine and helps support the teeth within the periodontium. cementoblasts are cementum-forming cells that are interposed between bundles of the periodontal ligament fibers, while cementocytes are cementoblasts that have been incorporated into the matrix (lieberman, 1994). the cementum-dentine junction (cdj) defines where the dental cementum incremental layers begin (jones, 1981). cementum is composed of incremental layers that follow the circumference of the roots and thickens with age. there have been correlations between the number of cement layers in humans cement and the number of years that have elapsed since root formation, indicating these layers are supposed to be deposited annually (hillson, 1986). generally, cementum layers can be viewed using transmitted light microscopy, scanning electron microscope (sem), or polarized light microscopy (hillson, 1986, 1996). the section thickness to view cementum layers properly is debated, and suggestions range from 10 to 100 µm (naylor et al., 1985; maat et al,. 2006; stamfelj et al., 2008). there is a large body of research pertaining to the assessment of age-at-death estimates in humans based on the number of dental cementum layers (charles et al., 1986; condon et al., 1986; kvaal and solheim, 1995; hillson, 1986; wittwer-backofen et al., 2004; renz and analysis of cementum layers in archaeological material michaela huffman1 and daniel antoine2 1department of anthropology, ohio state university, 4034 smith laboratory, 174 west 18th street, columbus, ohio 43210 2the british museum, great russell street london, united kingdom wc1b 3dg abstract the aim of this study was to assess the utility of cementum layers for estimating age at death of remains from an archaeological site. variability in cementum layer counts due to interobserver error and variation among dental regions were analyzed. interobserver error was later incorporated into age ranges based on counts of cementum layers and compared with age estimates derived from the skeleton. the layers were counted, using 9 teeth from 3 individuals, and the eruption age of the tooth was summed with the average layer count to achieve an estimated age. the research indicates that the assessment of archaeological dental cementum layers has a relatively high interobserver error. the cementum layer aging method resulted in large age ranges and did not correspond with age ranges from skeletal techniques. chemical diagenetic processes can affect the observation and count of cementum layers by obscuring bands and/ or creating additional bands. the variables that affected observability of cementum layers were: high interobserver error, discrepancy of readability of root regions, and large age ranges using the cementum layer technique that exceeded age ranges derived from other, skeletal methods dental anthropology 2010;23(3):67-73. correspondence to: michaela huffman, 1300 presidential drive, apartment 202, columbus, ohio 43212 e-mail: michaela.huffman@gmail.com or huffman.636@ buckeyemail.osu.edu radlanksi 2006). the majority of these studies were developed using modern human teeth (bosshardt and schroeder, 1991; maat et al., 2006; wedel, 2007; stamfelj et al., 2008). cementum layers were first examined in marine and hibernating land mammals, migratory ungulates and their dependent carnivores (morris, 1978; perrin and myrick, 1980; hillson, 1986), and the method is useful for determining chronological age. stott et al. (1982) evaluated the accuracy of age estimation using cementum layers in humans, and found a good correlation between the number of layers and the age-at-death in years. fewer studies have applied or tested this method on archaeological material (beasley et al., 1992; lieberman, 1994; klevezal and shishlina, 2001; jankauskas et al., 2001; stutz, 2002; hillson and antoine, 2003; maat et al., 2006; roksandic et al., 2009). recording such structures in archaeological teeth presents additional challenges not found in modern specimens. for instance, the integrity of dental tissue can be compromised through various diagenetic processes (lieberman, 1994; stutz, 2002) and, when the chronological age at death is unknown, establishing the accuracy of such methods is difficult. despite these issues, the method has often been applied to archaeological specimens (stutz, 2002; maat et al., 2006; roksandic et al., 2009). evaluating the recordability and accuracy of cementum layers as an ageing method in editor’s note: ms. huffman’s paper was awarded “first prize” for 2010 in the albert a. dahlberg student research competition sponsored by the dental anthropology association. 68 archaeological material should be carefully considered. previous studies have found cementum counts to be a useful method for estimating biological age in archaeological material (beasley et al., 1992; lieberman, 1994; jankauskas et al., 2001; klevezal and shishlina, 2001; maat et al., 2006). many of these studies conclude that cementum layers in archaeological material should give the same results as cementum layers in modern dentitions, as long as diagenetic processes do not affect the cementum and certain preparation methods are followed (section technique, type of microscopy). the results of roksandic et al. (2009) and stutz (2002) suggest that cementum in archaeological teeth is affected by diagenetic processes that can—particularly when observed in transmitted light microscopy –obscure layers or create optical artifacts in the form of extra cementum layers. these processes can result in observability and counting issues. this is particularly true of transmitted light microscopy, where the observation plane requires light to pass through several tens or hundreds of microns of tissue, offering ample opportunity for the light reflecting from each cementum layer to be affected by the optical properties of the tissue (roksandic et al., 2009). the present study focuses on human dental cementum in archaeological material, specifically with issues of observability, area of root with highest quality of cementum, and comparison to other aging methods. particular emphasis is placed on interobserver error, region of root correlating most closely with chronological age, and comparisons between this cementum-layer aging method and other aging techniques. understanding the variables that affect observability of archaeological cementum layers should aid establishing a best practice when using these layers to estimate biological age of individuals. materials and methods the specimens used were from the farringdon street excavation, london (1730-1849), currently housed at the museum of london. three individuals of unknown age were chosen from the collection, and were aged using the lovejoy et al. (1985) eight-phase auricular surface technique and the suchey-brooks (1990) six-phase pubic symphysis method. this aging method was chosen because it has been shown to give good estimates of age at death (scheuer and black, 2000; bass, 2005). three teeth were taken from each individual for a total of 9 teeth. a tooth was only used if an antimere was present so as to preserve the integrity of the museum of london collection. each specimen and tooth type was chosen on the basis of preservation, the presence of its antimere, and prior use in other published studies (table 1). typically, incisors, canines, premolars, and molars are used to count cementum layers (solheim, 1990; jankauskas et al., 2001), although some studies have indicated that premolars are a more reliable age indicator (condon et al., 1986; charles et al., 1986; renz et al., 1997). specimens were embedded in the methylmethacrylate (mm). the two-week slow curing of this resin allows it to be fully absorbed into the tooth, strengthening the cementum and allowing the integrity of the tissue to be preserved during sectioning and polishing (hillson, 1986). sectioning was performed as follows (adapted from antoine 2001): 1. a buehler isomet low speed saw with a diamond abrasive-edge blade was used for the sectioning with 1:1 distilled water: industrial methylated spirit (ims) as the lubricant. 2. two cuts were made. the first was taken approximately 50 µm from the central plane of the tooth. after the first cut, half of this block section was kept for scanning electron microscopy (sem). 3. the other half of the block was sectioned a second time to create a “thin” section. the cut was taken 900 µm (500 µm + the thickness of the blade) away from the first section plane towards the attached side of the tooth. this second cut was used for transmitted light microscopy. each tooth was sectioned from the tip of the cusp to the apex of the root. the incisors, canines, and premolars were sectioned longitudinally through the radial plane, orientated either buccolingal/palatal or labiolingual/ palatal (antoine et al., 2009). the molars were sectioned longitudinally via a tangential plane oriented through the tips of both the buccal/labial and lingual/palatal cusps (antoine et al., 2009). preparation of the sem blocks once the sectioning was accomplished, the halves kept for sem analysis were polished using an engis ltd kent mk2a polishing machine. the tooth was held onto a 3 µm and then a 1 µm hard plastic mat fixed to a rotating metal plate covered in 3 µm or 1 µm diamond polishing compound (metadi ii) and sprayed with dilap fluid as a lubricant (adapted from hillson, 1986). m. huffman and d. antoine table 1. tooth types of the 9 specimens analyzed specimen number tooth type fa090 1408 maxillary right canine (urc) maxillary right third premolar (urp3) mandibular right second molar (lrm2) fa090 1519 mandibular left central incisor (llci) maxillary right canine (urc) maxillary right third premolar (urp3) fa090 1116 maxillary right canine (urc) maxillary left fourth premolar (ulp4 mandibular right first molar (lrm1) 69 preparation of thin sections the thin sections were created to view the cementum layers under transmitted and polarized light microscopy. each thin section was polished using a lapping machine logitech ltd. pm2 (after antoine, 2001, 2009). 1. thin sections were temporarily fixed to glass slides with a thin layer of melted removable sticky wax (detrey model cementum dental sticky wax), vacuumheld to a jig (logitech pp5gt), and lapped down (approximately 50 µm to remove scratches or marks from the sectioning process); a 3 µm aluminium oxide abrasive solution was used as a lubricant-abrasive. 2. the polished portion of the tooth was desiccated in silica gel for 30 minutes, permanently mounted to another glass slide using photopolymeric cyanoacrylate resin (logitech uv resin 358), and exposed to uv light for 30 minutes. polishing thin sections once one side of a thin section had been mounted to a glass slide, the other surface of the specimens could be polished. 1. each specimen was polished on abrasive paper with finer grades of 600 and 1200, using deionized water as a lubricant. a glass plate with 3 µm aluminium oxide abrasive solution as the lubricant was used for the final polish to remove scratch marks. 2. each specimen was polished down progressively to 400, 300, 200, and 100 µm, and the appearance of the cementum layers was recorded at each thickness to determine the impact this may have on their observability. procedure for counting the incremental layers 1. two pictures from each progressive thickness were taken from each tooth. using digital images, the granular layer of tomes (glt) was located, a feature that is normally found near the end of the dentine and close to the cdj. 2. the cdj initiates where the cementum layers begin. cementum layer counts were recorded from the cdj to the root surface or the last preserved cementum layer (fig. 1). 3. the root was scanned and the clearest areas of dental cementum were selected for analysis (cervical, middle, or apical). one layer was defined from the border of two parallel darker lines. if the layers were difficult to find, the one layer was followed to another region where the increments were clear. if layers were not definable, pictures were taken to indicate no layering. in addition, if only a few layers were visible within the cementum thickness and large areas depicted no clear increments, the specimen was labeled as not having recordable layers. 4. each of the images for the individuals was counted on three separate occasions, to create an estimated age. age was calculated by adding the age of eruption of the tooth to the average count of cementum layers, using the schour and massler (1941) dental chart. the images and protocol for recording the layers were given to a colleague to count in order to assess interobserver error. variability in layer counts using the digitized images from transmitted light microscopy and from the sem, cementum layers were counted, age of eruption was then combined with the layer count to calculate chronological age. age ranges for each of the three individuals were then compared with the age ranges from the pubic symphysis (brooks and suchey 1990) and auricular surface (lovejoy et al. 1985). the interobserver error was tested on a subset of 9 randomly chosen images. the layers were counted twice fig. 1: this is an illustration of cementum layers. the cementum-dentine junction (cdj) is to the top; the root surface is to the bottom. each red dot identifies one clearly identifiable cementum layer. table 2. interobserver error for cementum layer counts layer layer count, count, specimen colleague author 1408 lrm2 400µm 63 24 1408 urc 400µm 29 31 1408 urp3 300µm 16 20 1116 ulp4 300µm 17 14 1519 urp3 200µm 42 20 1519 urp3 200µm 23 20 1116 urc 200µm 53 32 1116 ulp4 100µm 0 0 1116 lrm1 100µm 15 19 cementum layers in archaeological material 70 per image via a high definition computer screen at high magnification, and then compared with the author ’s previous counts. results aging using standard skeletal methods the 3 individuals were aged in the traditional methods of skeletal aging using the pubic symphysis and auricular surface. individual 1519 was the youngest of the three skeletons, determined to be 20-24 years of age. the second individual, 1116, was estimated to be between 35-39 years. specimen 1408 was the oldest of the three and was assessed to be 50-60 years (lovejoy et al., 1985). the interoberver error indicated that the layer counts were similar although there were differences for some specimens (table 2). the minimum difference between cementum counts was 0 and the maximum difference was 39. these results indicate that the process of counting cementum layers, even with a specific definition outlining the features constituting an increment, has a level of subjectivity (fig. 2). fig. 2. interobserver error of cement layer observations between author and colleague. (a) this is a transmitted light microscopy image of cementum layers on an upper right canine at 400 µm thickness. the author observed 31 layers, while a colleague observed 29 layers. (b) a transmitted light microscopy image of cementum layers on a lower right first molar at a 100 µm thickness. the author observed 19 layers, while a colleague observed 15 layers. table 3. visible layers present by region of root region no. of images % of of images not of visible visible root available n layers layers cervical 7 29 6 0.21 middle 7 29 5 0.17 apical 7 29 15 0.52 table 4. visible layers by section thickness and region of root section cervical middle apical thickness region region region 100 µm 0.00 0.25 0.63 200 µm 0.14 0.29 0.57 300 µm 0.50 0.00 0.50 400 µm 0.25 0.13 0.38 fig. 3. scanning electron microscopy (sem) image depicting poorly defined cementum layering. the white line indicates the length of the cement layers. most sem blocks showed very few layers due to cracks affecting the imaging. m. huffman and d. antoine 71 all regions of the root (cervical, middle, apical) were viewed in order to assess and count all cementum layers. the apical region of the root indicated the clearest area for observing and counting cementum layers (tables 3-4). when using sem imaging, cementum layers were not visible in the majority of the specimens (fig. 3). transmitted light microscopy was found to be optimal for observing the cementum layers. section thicknesses of 200 µm to 300 µm viewed under transmitted light microscopy showed the clearest cementum layers. the apical region of the root showed the clearest images of visible cementum layering in the majority of specimens. in general, the upper right third premolar consistently exhibited cementum layering. this study found cementum layers tend to overestimate age in the younger individual, concurring with other studies (miller et al., 1988; kvaal and solheim, 1995; meinl et al., 2008). the present study found cementum layers to underestimate the older individuals in accord with other research (miller et al., 1988; kvaal and solheim, 1995; meinl et al., 2008). overall, many ranges of cementum layer counts were found for each individual. for example, layer counts for individual 1116 specimen lrm1 at 400 µm ranged from 20-30, and at 300 µm 12-16 layers were identified. when the eruption age was added to these increments variable age ranges were found per each individual (table 5). discussion skeletal the appreciable between-observer differences reflect how difficult recording cementum structures can be. when the interobserver results were combined, the cementum age estimates were very large (table 6). the cementum layer estimates did not compare well with the pelvis age ranges. overall, he observation and recording of cementum layers has proven to be difficult. the apical region of the root proved to be the best area to observe and count cementum layers. cementum layers in the cervical and middle regions of the root were markedly unclear and nearly incalculable in the majority of sections. perhaps diagenetic processes or the sectioning technique rendered these regions of cementum unusable. counting cementum layers as an estimate of the age-of-death resulted in a broad range of age estimates. unfortunately, the accuracy of cementum layering for aging individuals in the present study cannot be compared to other studies, in part because the skeletal specimens were of unknown age. many of the research studies have used modern teeth (zander and hurzeler, 1958; charles et al., 1986; kvaal et al., 1996; renz and radlanski, 2006); only a few have actually used archaeological specimens (lieberman, 1994; jankauskas et al., 2001; wittwer-backofen et al., 2008; roksandic et al., 2009). as previously observed by lieberman, using archaeological specimens to observe incremental layers can be problematic: unidentified diagenetic processes may affect the optical properties of the cementum with the dissolution of collagen reducing the number of visible layers and microbial action removing outer layers (lieberman, 1994). indeed, chemical diagenic processes such as collagen leaching (removal of collagen through water or other liquids) and apatite recrystallization (development of banded features that mimic cementum layers) can both dissolve layers or create extra bands, affecting the technique’s accuracy (stutz, 2002). the integrity of the dental cementum can also be compromised in archaeological specimens. the present study found that the more rapidly growing cellular cementum found at the apex of the root showed the clearest layers, whereas the slower and thinner acellular cementum layers found in the middle and cervical regions were difficult to observe. in their study of the applicability of cementum layers aging in archaeological specimens roksandic et al. (2009) reported similar problems. approximately 80% of the teeth were discarded because the cementum layers appeared to be compromised by diagenic processes causing wavy lines that were interspersed with pits, impurities bifurcating lines, and partially obscured lines (roksandic et al., 2009). they also found that the cervical and middle regions of the cementum were the most difficult to record and most likely affected by diagenic processes. the present study found that, in archaeological material, the observation of cementum layers can be difficult, and there is variability in the readability of various regions of the root, possibly caused by diagenic processes. evaluating and understanding the variables that may affect the observability of archaeological cementum layers should be a prerequisite to assessing how useful cementum layers are in estimating biological table 5. average counts of cementum layering for each specimen with eruption age compared with skeletal age estimate using the auricular surface† cementum skeletal specimen layer age range age range 1116 27-37 35-39 1519 24-43 20-24 1408 33-35 50-60+ †eruption age of each tooth specimen was totaled with averaged cementum layer count to compile age ranges. table 6. age range for each individual cementum cementum and combined skeletal layer age interobserver age specimen range age range range 1519 24-43 24-52 20-24 1116 27-37 21-64 35-39 1408 33-35 26-75 50-60+ cementum layers in archaeological material 72 age. unfortunately for archaeologists, the growth structures in the cementum of ancient teeth often are difficult to observe. when they are observed, the number of visible layers can be affected by diagenetic processes, compromising their use as an aging technique. conclusion the present study studied incisors, canines, premolars, and molars, cut and polished at progressively thin sections from archaeological specimens of unknown ages. interobserver error indicated that viewing and counting cementum layers can prove to be a difficult process that can lead to large age ranges per individual. the readable and unreadable segments of the various root regions are disconcerting and can lead to a high level of subjectivity that increases intraand interobserver error. chemical diagenetic processes affect the integrity of archaeological dental tissue, often obscuring and/or creating additional layers within the cementum. the current study has found that there are incremental layers within dental cementum that correlate positively with age, although there is little understanding of the significance of these layers. evaluating archaeological dental material and the variables, such as subjectivity in counts and diagenetic processes, that affect the observability of cementum layers is important. therefore, to successfully evaluate the aging technique of cementum layers using archaeological material, researchers must understand the problems of observability. research should focus on understanding the biological process of cementum formation, as well as an examination of how diagenetic processes affect archaeological dental tissue. acknowledgements i want to thank the museum of london for providing access to their skeletal collections, and debbie guatellisteinberg for her critiques and comments throughout my writing process. references cited antoine d, hillson s, dean mc. 2009. the developmental clock of dental enamel: a test for the periodicity of prism cross striation. j anat 214:45-55. antoine d. 2001. evaluating the periodicity of incremental structures in dental enamel as a means of studying growth in children from past human populations. ph.d. dissertation, university college london. bass wm. 2005. human osteology: a laboratory and field manual. columbia, missouri: missouri archaeological society. beasley mj, brown wab, legge aj. 1992. incremental banding in dental cementum: methods of preparation for teeth from archaeological sites and for modern comparative specimens. int j 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bioarchaeological collections. documenta archaeobiologiae, rahden/westf.: leidorf. p 141-157. jankauskas r, barakauskas s, bojarun r. 2001. incremental lines of dental cementum in biological age estimation. homo 52:59-71. jones sj. 1981. human tissue: cement. in: osborn jw, editor. dental anatomy and embryology. london, england: blackwell scientific publications. p 193-209. klevezal ga, shishlina ni. 2001. assessment of the season of death of ancient human from cementum annual layers. j arch sci 28:481-486. kvaal si, solheim t. 1995. incremental lines in human dental cementum in relation to age. eur j oral sci 103:225-230. kvaal si, solheim t, bjerketvedt d. 1996. evaluation of preparation, staining, and microscopic techniques for counting incremental lines in cementum of human teeth. biotech histochem 71:165-172. lieberman de. 1994. the biological basis for seasonal increments in dental cementum and their application to archaeological research. j arch sci 21:525-539. lovejoy co, 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enhancement: a technique for age determination in man. am j phys anthropol 68:197-200. perrin wf, myrick ac. 1980. growth of odontocetes and sirenians: problems in age determination. proceedings of the international conference on determining age of odontocete ceteans. la jolla, california, september 5-19, 1978, report of the international whaling commission, special issue no. 3, cambridge: international whaling commission. renz h, schaefer v, duschner h, radlanski rj. 1997. incremental lines in root cementum of human teeth: an approach to their ultrastructural nature by microscopy. adv dent res 11:472-477. renz h, radlanksi rj. 2006. incremental lines in root cementum of human teeth—a reliable age marker? homo 57:29-50. roksandic m, vlak d, schillaci ma, voicu d. 2009. applicability of tooth cementum annulation to an archaeological population. am j phys anthropol 140:583-588. scheuer l, black s. 2000. developmental juvenile osteology. london, england: elsevier academic press. schour i, massler m. 1941. the development of the human dentition. j am dent assoc 28: 1153-1160. solheim t. 1990. dental cementum apposition as an indicator of age. scand j dent res 98:510-519. stamfelj i, vidmar g, cvetko g, gaspersic d. 2008. cementum thickness in multirooted human molars: a histometric study by light microscopy. ann anat 190:129-139. stott gg, sis rf, levy bm. 1982. cementum annulation as an age criterion in forensic dentistry. j dent res 61:814-817. stutz aj. 2002. polarizing microscopy identification of chemical diagenesis archaeological cementum. j arch sci 29:1327-1347. wedel vl. 2007. determination of season at death using dental cementum increment analysis. j for sci 52:1-4. wittwer-backofen u, buckberry j, czarnetzki a, doppler s, grupe g, hota g, kemkes a, larsen cs, prince d, wahl jj, fabig a, weise s. 2008. basics in paleodemography: a comparison of age indicators applied to the early medieval skeletal sample of lauchheim. am j phys anthropol 123:119-129. zander ha, hurzeler b. 1958. continuous cementum apposition. j dent res 37:1035-1044. the 15th international symposium on dental morphology will be held from 24-27 august, 2011 at northumbria university in newcastle upon tyne, united kingdom, sponsored by the newcastle university school of dental sciences. this symposium will bring together scholars from around the world to present research in all aspects of dental morphology. the range of presentations will be broad and include topics such as dental anthropology, dental evolution, dental function, growth and development, dental tissues, and the genetics and clinical aspects of dental morphology. for more information or to be added to our mailing list, please contact dr wendy dirks (wendy.dirks@ncl.ac.uk ). cementum layers in archaeological material fitzgerald 2009.4 57 shelley saunders, a distinguished physical anthropologist and well loved professor at mcmaster university in canada, finally succumbed in 2008 to the cancer that had haunted her through the last decade and a half of her life. she was no pushover for the disease, which struck first in the early 1990s, and was thought to have been cured, but which returned again, resulting in the loss of both of her kidneys in 2003. this necessitated daily haemodialysis that constrained her ability to travel, but had no material effect on her research output and her teaching until the cancer reappeared in her pancreas more than four years later. her audacious battle was emblematic of the way she approached life. she resisted, uncomplaining, with great fortitude and with all of her might until the very end. shelley did not need urging not to go gently into that good night, nor to rage, rage against the dying of the light. nevertheless, she was taken in the early autumn of her life; there are few of whom it can so sincerely be said, she had so much more to give. in many respects shelley was a renaissance scholar in our field, as a glance at her bibliography will show. her primary focus was on dental and skeletal biology and bioarchaeology and forensics, but her scope of interest was very broad. she also published on evolutionary theory, demography, isotopic and palaeodiet studies and was a pioneer in ancient dna. her honours are legion and her career is marked by a long series of “firsts”. she was the first biological anthropologist to be elected to the royal society of canada, a signal honour. she was in the first tranche of tier 1 canada research chairs, a federal grant, tenable for seven years, awarded to outstanding researchers acknowledged by their peers as world leaders in their fields. shelley initiated the children and childhood in human societies research network. she founded and established an ancient dna laboratory at mcmaster, now called the mcmaster ancient dna centre, and she created and later expanded the mcmaster anthropology hard tissue and light microscopy laboratory to study growth and development. although set up to investigate both bones and teeth, concentration in the last decade or more had been on teeth, with particular emphasis on odontochronological analysis in deciduous teeth. she was the recipient of many academic awards, but despite her elite stature in canada she was an extraordinarily humble person—quiet, reserved, gentle, kind, and scrupulously fair—more likely to talk about the achievements of her many students than about her own. devotion to her students was one of shelley’s hallmarks. she loved to teach and was indeed an educator of distinction, someone who relished training bright obituary: shelley rae saunders (1950–2008) charles fitzgerald* department of anthropology, mcmaster university, toronto *correspondence to: charles fitzgerald, department of anthropology, mcmaster university, canada e-mail: drtooth59@cogeco.ca fig. 1. shelley at work in her laboratory (photo courtesy of the hamilton spectator newspaper). 58 minds. she was dedicated to getting undergraduates engrossed in learning and discovery. she invented innovative ways to achieve this, and was famous amongst students for her bone groan quizzes, for her dental jeopardy games, her bioanth bingo and skeletal crossword puzzles. however, shelley’s greatest enjoyment came from working with and developing her graduate students, and she took enormous pride in their accomplishments. her skilled supervision and devoted mentorship earned her the president’s award for excellence in graduate supervision at mcmaster and her former students now teach at universities across canada, the united states and europe. one of her last acts demonstrates her commitment to students. at her behest, just days before her death, she and her family established the shelley saunders graduate scholarship with a generous donation of $500,000, which was supplemented by contributions from friends and well wishers of another $50,000. this fund will sponsor annually two graduate students who wish to pursue research in dental or skeletal biology at mcmaster. the canadian association of physical anthropologists, of which she was an active member through her whole career, has also established a grant in her honour to c.m. fitzgerald fig. 2. a younger shelley in front of an unidentified mesoamerican pyramid. provide supplemental research funding for graduate students. shelley grew up in toronto and new jersey and met victor koloshuk, her beloved husband of 37 years, while they were both undergraduates. she received her ph.d. in anthropology from the university of toronto in 1977, defending her dissertation while pregnant with their first child, robert. after the birth of their second child, barbara, and after teaching anatomy at mcgill and contract teaching at the university of toronto, she was offered a tenure-track position in the department of anthropology at mcmaster university in 1981. she went on to become the central pillar of mcmaster ’s program in physical anthropology and her numerous research projects over the years received international recognition. among the most notable was a complex, multidisciplinary project that she directed on a large nineteenth-century cemetery from st. thomas’ anglican church in belleville, ontario, which presented the rare opportunity to work with skeletal and dental material associated with individuals of known age-atdeath. shelley’s projects also took her to europe, for instance to the university of bordeaux where she was involved in the analysis of a medieval population from south-western france, or the czech republic where she conducted histological analysis of ancient egyptian pharaonic samples. she developed a particularly rich collaboration with italian colleagues from the pigorini museum in rome on the imperial roman site of isola sacra. she was also familiar to the canadian media through her work in forensic anthropology for the hamilton regional forensic pathology unit and a number of local and royal canadian mounted police forces, where some of her cases often received considerable attention. shelley had a very prolific publication record, amongst which were six co-edited volumes, the latest, biological anthropology of the human skeleton, co-edited with anne katzenberg, was published in march of 2008. she served on the editorial board of the american journal of physical anthropology from 1994 to 2000 and was north american editor of the international journal of osteoarchaeology until shortly before her death. shelley was a great teacher, a nonpareil researcher, an expert biological anthropologist, a wonderful colleague, an avid gardener and opera fan, and before dialysis curtailed it, someone who loved to travel. she possessed all of the qualities required for distinction in any field: keen intelligence, great tenacity, the capacity for hard work, terrific organising and planning skills, and an ability to extract the best from those around her. she will be remembered with deep affection by a host of current and former graduate students, friends, and colleagues. her contributions to our field will also be sorely missed. 59 shelley r. saunders bibliography prowse tl, saunders sr, fitzgerald cm, bondioli l, macchiarelli r. 2009. growth, morbidity, and mortality in antiquity: a case study from imperial rome. in: moffat t, prowse tl, eds. human diet and nutrition in biocultural perspective (in press). oxford: berghahn. cardoso hf, saunders sr. 2008. two arch criteria of the ilium for sex determination of immature skeletal remains: a test of their accuracy and an assessment of intraand inter-observer error. forensic sci int 178:24-29. katzenberg ma, saunders sr, eds. 2008. biological anthropology of the human skeleton, second edition. new york: wiley. prowse tl, saunders sr, schwarcz hp, garnsey p, macchiarelli r, bondioli l. 2008. isotopic and dental evidence for infant and young child feeding practices in an imperial roman skeletal sample. am j phys anthropol. saunders sr. 2008. subadult skeletons and growth-related studies. in: katzenberg ma, saunders sr, eds. biological anthropology of the human skeleton, second edition. new york: wiley. p 117-148. saunders sr, rainey dl. 2008. nonmetric trait variation in the skeleton: abnormalities, anomalies, and atavisms. in: katzenberg ma, saunders sr, eds. biological anthropology of the human skeleton, second edition. new york: wiley. p 533-560. saunders sr, chan ah, kahlon b, kluge hf, fitzgerald cm. 2007. sexual dimorphism of the dental tissues in human permanent mandibular canines and third premolars. am j phys anthropol 133:735-740. von hunnius te, yang d, eng b, waye js, saunders sr. 2007. digging deeper into the limits of ancient dna research on syphilis. j arch sc 34:2091-2100. albanese j, saunders sr. 2006. is it possible to escape racial typology in forensic identification? in: schmitt a, cunha e, pinheiro j, eds. forensic anthropology and medicine: complementary sciences from recovery to cause of death. totowa, nj: humana press. p 281-316. beauchesne p, saunders sr. 2006. a test of the revised frost’s ‘rapid manual method’ for the preparation of bone thin sections. int j osteoarch 16:82-87. fitzgerald cm, saunders sr, bondioli l, macchiarelli r. 2006. health of infants in an imperial roman skeletal sample: perspective from dental microstructure. am j phys anthropol 130:179-189. von hunnius te, roberts ca, boylston a, saunders sr. 2006. histological identification of syphilis in pre-columbian england. am j phys anthropol 129:559-566. albanese j, cardoso hfv, saunders sr. 2005. universal methodology for developing univariate sample-specific sex determination methods: an example using the epicondylar breadth of the humerus. j arch sc 32:143-152. fitzgerald cm, saunders sr. 2005. test of histological methods of determining chronology of accentuated striae in deciduous teeth. am j phys anthropol 127:277-290. katzenberg ma, oetelaar g, oetelaar j, fitzgerald cm, yang dy, saunders sr. 2005. identification of historical human skeletal remains: a case study using skeletal and dental age, history and dna. int j osteoarch 15:61-72. prowse tl, schwarcz hp, saunders sr, macchiarelli r, bondioli l. 2005. isotopic evidence for age-related variation in diet from isola sacra, italy. am j phys anthropol 128:2-13. prowse tl, schwarcz hp, saunders sr, macchiarelli r, bondioli l. 2004. isotopic paleodiet studies of skeletons from the imperial roman-age cemetery of isola sacra, rome, italy. j arch sc 31:259-272. yang dy, cannon a, saunders sr. 2004. dna species identification of archaeological salmon bone from the pacific northwest coast of north america. j arch sc 31:619-631. dudar jc, waye js, saunders sr. 2003. determination of a kinship system using ancient dna, mortuary practice, and historic records in an upper canadian pioneer cemetery. int j osteoarch 13:232. yang dy, eng b, saunders sr. 2003. hypersensitive pcr, ancient human mtdna, and contamination. hum biol 75:355-364. saunders sr, herring da, sawchuk la, boyce g, hoppa rd, klepp s. 2002. the health of the middle class: the st. thomas’ anglican church cemetery project. in: steckel rh, rose jc, eds. the backbone of history: health and nutrition in the western hemisphere. cambridge: cambridge university press. p 130-161. strouhal e, vyhnánek l, gaballah mf, saunders sr, woelfli w, bonani g, nemeckova a. 2001. identification of royal skeletal remains from egyptian pyramids. anthropologie xxxix:15-23. katzenberg ma, saunders sr, abonyi s. 2000. bone chemistry, food and history: a case study from 19th century upper canada. in: ambrose sh, katzenberg ma, eds. biogeochemical approaches to paleodietary analysis. new york: plenum. p 1-22. katzenberg ma, saunders sr, eds. 2000. biological anthropology of the human skeleton. new york: wiley. saunders sr. 2000. subadult skeletons and growth-related studies. in: katzenberg ma, saunders sr, eds. biological anthropology of the human skeleton. new york: wiley. p 135-161. saunders sr, hoppa rd, macchiarelli r, bondioli l. 2000. investigating variability in human dental development in the past. anthropologie xxxviii:101-107. obituary: shelley rae saunders (1950–2008) 60 fitzgerald cm, saunders sr, macchiarelli r, bondioli l. 1999. large scale histological assessment of deciduous crown formation. in: mayhall jt, heikkinen t, eds. proceedings of the 11th international symposium of dental morphology, aug 26-30, 1998, oulu, finland. oulu, finland: oulu university press. p 92101. garlie tn, saunders sr. 1999. midline facial tissue thicknesses of subadults from a longitudinal radiographic study. j forensic sci 44:61-67. saunders sr, yang dy. 1999. sex determination: xx or xy from the human skeleton. in: fairgrieve si, ed. forensic osteological analysis: a book of case studies. springfield, il: charles c. thomas. p 36-59. saunders sr, keenleyside a. 1999. enamel hypoplasia in a canadian historic sample. am j hum biol 11:513-524. saunders sr, barrans l. 1999. what can be done about the infant category in skeletal samples? in: hoppa rd, fitzgerald cm, eds. human growth in the past. cambridge, england: cambridge university press. p 183-209. herring da, saunders sr, katzenberg ma. 1998. investigating the weaning process in past populations. am j phys anthropol 105:425-439. hoppa rd, saunders sr. 1998. two quantitative methods for rib seriation in human skeletal remains. j forensic sci 43:174-177. hoppa rd, saunders sr. 1998. the mad legacy: how meaningful is mean age-at-death in skeletal samples? human evolution 13:1-14. saunders sr. 1998. erratum: dental caries in nineteenth century upper canada. am j phys anthropol 104:7187. am j phys anthropol 105:405. strouhal e, fawzi gaballah m, bonani g, woelfli w, nemeckova a, saunders sr. 1998. re-investigation of the remains thought to be of king djoser and those of an unidentified female from the step pyramid at saqqara. in: eyre cj, ed. proceeding of the seventh international congress of egyptologists. leuven: uitgeverij peeters publishers. yang dy, eng b, waye js, dudar jc, saunders sr. 1998. technical note: improved dna extraction from ancient bones using silica-based spin columns. am j phys anthropol 105:539-543. grolleau-raoux jl, crubezy e, rouge d, brugne jf, saunders sr. 1997. harris lines: a study of age-associated bias in counting and interpretation. am j phys anthropol 103:209-217. saunders sr, hoppa rd. 1997. sex allocation from long bone measurements using logistic regression. can soc forensic sci j 30:49-60. saunders sr, devito c, katzenberg ma. 1997. dental caries in nineteenth century upper canada. am j phys anthropol 104:71-87. sperduti a, bondioli l, hoppa rd, prowse tl, salomone f, saunders sr, yang yh, macchiarelli r. 1997. il segmento infanto-giovanile della communità romana imperiale del portus romae. antropologia contemporanea xii congresso degli antropologi italiani. storia del popolamento del mediterraneo: aspetti antropologici, archeologici e domografici, palermo. brugne jf, cleuvenot e, murail p, pujol j, rouge d, saunders sr. 1996. un homme grand et jeune. in: crubezy e, dieulafait c, eds. le comte de l’an mil (supp. 8). talence: federation aquitania. katzenberg ma, herring da, saunders sr. 1996. weaning and infant mortality: evaluating the skeletal evidence. yrbk phys anthropol 39:177-199. saunders sr. 1995. the enduring tension: conflicts between darwinian and lamarckian models of inheritance. in: herring da, chan l, eds. strength in diversity. toronto: canadian scholar’s press. p 1-20. saunders sr, herring da, eds. 1995. grave reflections. portraying the past through cemetery studies. toronto: canadian scholars’ press. saunders sr, herring da, sawchuk la, boyce g. 1995. the nineteenth-century cemetery at st. thomas’ anglican church, belleville: skeletal remains, parish records, and censuses. in: saunders sr, herring da, eds. grave reflections: portraying the past through cemetery studies. toronto: canadian scholars’ press. p 93-118. saunders sr, herring da, boyce g. 1995. can skeletal samples accurately represent the living populations they come from? the st. thomas’ cemetery site, belleville, ontario. in: grauer aj, ed. bodies of 4vidence: reconstructing history through skeletal analysis. new york: john wiley & sons inc. p 69-89. hoppa rd, saunders sr. 1994. the δ/method for examining bone growth in juveniles: a reply. int j osteoarch 4:261-263. rogers tl, saunders sr. 1994. accuracy of sex determination using morphological traits of the human pelvis. j forensic sci 39:1047-1056. dudar jc, pfeiffer s, saunders sr. 1993. evaluation of morphological and histological adult skeletal age-atdeath estimation techniques using ribs. j forensic sci 38:677-685. katzenberg ma, saunders sr, fitzgerald wr. 1993. age differences in stable carbon and nitrogen isotope ratios in a population of prehistoric maize horticulturists. am j phys anthropol 90:267-281. saunders sr, hoppa rd, southern r. 1993. diaphyseal growth in a nineteenth century skeletal sample of subadults from st thomas’ church, belleville, ontario. int j osteoarch 3:265-281. saunders sr, hoppa rd. 1993. growth deficit in survivors and nonsurvivors—biological mortality bias in subadult skeletal samples. yrbk phys anthropol 36:127-151. c.m. fitzgerald 61 saunders sr, devito c, herring da, southern r, hoppa rd. 1993. accuracy tests of tooth formation age estimations for human skeletal remains. am j phys anthropol 92:173-188. saunders sr. 1992. can revisionism, in evolutionary biology help in formulating hypotheses about hominid evolution? human evolution 7:25-35. saunders sr, herring da, ramsden pg. 1992. transformation and disease: precontact ontario iroquoians. in: verano jw, ubelaker dh, eds. disease and demography in the americas. washington: smithsonian institution press. p 117-126. saunders sr. 1992. subadult skeletons and growth related studies. in: saunders sr, katzenberg ma, eds. skeletal biology of past peoples: research methods. new york: wiley-liss. p 1-20. saunders sr, katzenberg ma, eds. 1992. skeletal biology of past peoples: research methods. new york: wiley-liss. saunders sr, fitzgerald cm, rogers tl, dudar jc, mckillop h. 1992. a test of several methods of skeletal age estimation using a documented archaeological sample. can soc forensic sci j 25:97-118. herring da, saunders sr, boyce g. 1991. bones and burial registers: infant mortality in a 19th-century cemetery from upper canada. northeast hist arch 20:54-70. saunders sr. 1991. the snake hill skeletal sample: sex determination, stature, and limb bone size and shape variation. in: pfeiffer s, williamson rf, eds. snake hill: an investigation of a military cemetery from the war of 1812. toronto: dundurn press. saunders sr, devito c. 1991. subadult skeletons in the raymond dart anatomical collection: research potential. human evolution 6:421-434. saunders sr, lazenby ra, eds. 1991. the links that bind: the harvie family nineteenth century burying ground. dundas, ont: copetown press. devito c, saunders sr. 1990. a discriminant function analysis of deciduous teeth to determine sex. j forensic sci 35:845-858. saunders sr, melbye jf. 1990. subadult mortality and skeletal indicators of health in late woodland ontario iroquois. canadian journal of archaeology 14:61-74. lazenby ra, oliver l, saunders sr. 1989. use of rib histomorphometry as an aid in the personal identification of unknown skeletons: the paleophysiology of three hanged men. can soc forensic sci j 22:261-272. saunders sr. 1989. nonmetric skeletal variation. in: iscan my, kennedy kar, eds. reconstruction of life from the skeleton. new york: alan r. liss. p 95-108. saunders sr. 1989. what’s read in the bone. rotunda 21:47-53. saunders sr. 1988. bone growth, modeling and remodeling. recherches amérindiennes au québec 18:49-58. saunders sr, mackenzie-ward d. 1988. the reid site human burials. kewa 88:21-26. saunders sr. 1987. growth remodeling of the human femur. canad rev phys anthropol 6:20-30. mayhall jt, saunders sr. 1986. dimensional and discrete dental trait asymmetry relationships. am j phys anthropol 69:403-411. saunders sr, spence ma. 1986. dental and skeletal age determinations of ontario iroquois infant burials. ont arch 46:21-26. saunders sr. 1985. the inheritance of acquired characteristics: a concept that will not die. in: godfrey lr, ed. what darwin began: modern darwinian and non-darwinian perspectives on evolution. boston: allyn and bacon. p 148-161. saunders sr. 1985. inheritance and evolution: the role of lamarckism in contemporary biology. canad rev phys anthropol 4:93-100. saunders sr. 1985. surface and cross-sectional comparisons of bone growth remodeling. growth 49:105-130. mayhall jt, saunders sr, belier pl. 1982. the dental morphology of north american whites: a reappraisal. in: kurtén b, ed. teeth: form, function, and evolution. new york: columbia university press. p 245-258. saunders sr, mayhall jt. 1982. fluctuating asymmetry of dental morphological traits: new interpretations. hum biol 54:789-799. saunders sr, mayhall jt. 1982. developmental patterns of human dental morphological traits. arch oral biol 27:45-49. saunders sr, popovich f, thompson gw. 1980. a family study of craniofacial dimensions in the burlington growth centre sample. am j orthod 78:394-403. saunders sr, popovich f. 1978. a family study of two skeletal variants: atlas bridging and clinoid bridging. am j phys anthropol 49:193-203. saunders sr. 1978. the development and distribution of discrete traits of the human infracranial skeleton. ottawa: archaeological survey of canada, mercury series no. 81. compiled by: charles fitzgerald department of anthropology mcmaster university canada obituary: shelley rae saunders (1950–2008) harris and barcroft 2010.4 83 it is commonly appreciated that teeth differ among human groups both as regards shape as well as size. part of this is due to differences in the prevalence and degree of crown traits, such as incisor shoveling (hrdlička, 1920) and molar cusp number (harris and bailit, 1980), but other differences involve the proportionality of crown components such as relative cusp sizes (turner et al., 1991; townsend et al., 2003; harris and dinh, 2006) two of the prominent races in the united states are blacks and whites. the 2000 census of the u.s. lists selfassessed proportions of blacks and whites at about 13% and 65%, respectively. the dental anthropology of american blacks is not known as well as for the majority whites, partly because blacks are unevenly distributed geographically, being concentrated in the southeast. anthropological dental studies are primarily limited to tooth eruption and crown sizes. studies document the early development of teeth in american blacks vis-à-vis american whites. we are aware of two studies of the primary dentition (both dealing with tooth emergence); both show a precedence of american blacks compared to american whites (ferguson et al., 1957; infante, 1974). the serial study of children from tuskeegee, alabama (steggerda and hill, 1942) and national u.s. epidemiological studies have collected data on the ages of emergence of the permanent teeth (garn et al., 1972, 1973), but fewer data are available on crown sizes. the study by richardson and malhotra (1975, 1976) based on the meharry growth study (nashville, tennessee) probably is the best known and most commonly cited study for the permanent teeth of american blacks (n ≈ 160). ferguson et al. (1978; macko et al., 1979) reported american black-white differences in primary tooth crown shape: the crown index edward f. harris* and betsy d. barcroft department of pediatric dentistry, university of tennessee, memphis. *correspondence to: edward f. harris, college of dentistry, university of tennessee, memphis, tennessee 38167. e-mail: eharris@uthsc.edu on a sample of blacks (n ≈ 113) from the university of connecticut. keene (1979) described mesiodistal crown lengths in black male u.s. navy recruits (also keene, 1967). as for the primary dentition, moss and colleagues (1966a,b) published data on liberian (west-central africa) primary tooth sizes, but sample sizes were small (8 to 19 extracted teeth per type, sexes combined). hanihara (1976) studied a sample of blacks (n ≈ 65) at the university of chicago. vaughan and harris (1992) described a sample of 100 blacks collected at the university of tennessee. anderson (2005, 2006, 2007) described tooth crown sizes of a large sample (n ≈ 1,124) of american blacks from howard university (washington, d.c.) to our knowledge, prior studies have been limited to the mesiodistal (md) and buccolingual (bl) dimensions themselves, though hanihara did employ multivariate statistics. the purpose of the present study is to compare tooth crown shapes—ratios of bl width to md depth—in the primary teeth from samples of american blacks and whites from the u.s. mid-south. this report was stimulated by exploratory findings that suggested that blacks have significantly different crown indices than whites, and the present study explores that finding in more detail. abstract: the purpose of this tooth-size study was to compare the crown index—the ratio of buccolingal to mesiodistal crown size—in the primary teeth of contemporary american blacks and whites. maximum md and bl drown dimensions were obtained with sliding calipers from dental casts of children attending the graduate pedodontic and orthodontic clinics at the university of tennessee, memphis (n = 226). the crown index (bl/md times 100) was calculated for all 10 tooth types (left and right sides were averaged prior to calculation). only the maxillary first molar exhibited a significant sex difference (girls have a higher crown index). in contrast, 9 of the 10 tooth types have signficantly higher crown indices in blacks than whites. analysis of the md and bl crown diameters reveals that the race differencs are due exclusively to differences in mesiodistal crown lengths; the buccolingual crown breadths do not differ between these two races. consequently, the crown indices are higher in blacks because of their larger md dimensions. differences in the indices conform to prior findings that american blacks have larger tooth crowns than whites in both the primary and permanent dentitions, and this study shows that the differences are due to the md not the bl crown axis. study of the crown components will shed light on how the crown shapes differ between these two races. dental anthropology 2010;23(3):83-88. 84 materials and methods full-mouth hydrocolloid casts were taken on children in the primary or early mixed dentitions. these were poured immediately in dental stone. children were routine, phenotypically normal children attending the graduate pediatric or orthodontic dental clinic at the university of tennessee, memphis. race (either black or white) was based on the parent’s self-assessment (edgar and hunley 2009). total sample size was 226 with proportionate samples by race and sex. maximum mesiodistal and buccolingual crown dimensions were measured as described by seipel (1946) using sliding calipers with an electronic-readout precision of 0.005 mm. data were collated in an excel® spreadsheet (microsoft corporation, redmond, wa), and then uploaded to jmp® version 9 (sas institute inc., cary, nc) for statistical analysis. all measurements were obtained twice. when the repeated measures differed by more than 0.2 mm, which was rare, a third measurement was taken with the two closest values being averaged. teeth were measured on both the left and right sides, and analysis is based on the left-right averages. the random component of the intra-observer repeatability was calculated using the standard dahlberg statistic: me = x 1i -x 2i( ) 2 i= 1 n ∑ 2n where x 1i and x 2i are the repeated measurements for case “i” and n is the number of cases (dahlberg, 1940) and “me” stands for method error. the dahlberg statistic is 0.012 mm. in other words, the standard error of the technical error of measurement (i.e., the error due to variability in measuring the teeth) is about one-hundredth of a millimeter. this is very small, and it does not account for any of the differences claimed to be significant statistically. table 1. results of two-way analysis of variance for each of the 10 tooth types testing for a race and/or sex difference in the crown index tooth race sex interaction type df f p value df f p value df f p value maxilla i1 1 4.22 0.0421 1 0.01 0.9249 1 0.32 0.5742 i2 1 11.86 0.0008 1 1.89 0.1714 1 0.62 0.4332 c 1 0.03 0.8658 1 1.02 0.3139 1 0.29 0.5902 m1 1 7.97 0.0053 1 11.99 0.0007 1 3.26 0.0728 m2 1 18.04 <0.0001 1 2.27 0.1336 1 0.00 0.9470 mandible i1 1 10.95 0.0013 1 0.27 0.6031 1 1.84 0.1781 i2 1 4.66 0.0326 1 0.03 0.8588 1 0.65 0.4220 c 1 10.50 0.0014 1 0.49 0.4859 1 0.02 0.8890 m1 1 40.20 <0.0001 1 0.40 0.5302 1 5.36 0.0217 m2 1 16.18 <0.0001 1 1.83 0.1773 1 0.47 0.4950 fig 2. boxplots for the crown index of the lower first molar. this tooth type has the largest f-ratio, and “race” accounts for 17% of the total variance. the raceby-sex interaction for this variable (table 2) is due to the higher crown index in white girls compared to white boys, whereas there is no sex difference in the samples of blacks. the smaller index in blacks than whites is due to their greater md crown length rather than any difference in bl breadth. e.f. harris and b.d. barcoft 85 table 2. results of one-way anova testing for black-white differences in the crown index (sexes pooled) tooth r2 (%) n f ratio p value maxilla i1 3.25 125 4.13 0.0442 i2 7.01 148 11.01 0.0011 c 0.01 182 0.02 0.8816 m1 4.91 183 9.35 0.0026 m2 9.49 179 18.57 <0.0001 mandible i1 10.18 108 12.02 0.0008 i2 3.54 137 4.96 0.0276 c 5.55 188 10.93 0.0011 m1 17.57 181 38.16 <0.0001 m2 7.86 184 15.53 0.0001 in a complementary fashion, the percentage of measurement size due to technical error of measurement (sokal and rohlf, 1991) also was computed. the formula is: x 1 − x 2 x 1 + x 2 2       × 100 the average difference is 0.18%, meaning that the average percent of tooth size attributable to tem is much less than 1% of the tooth’s diameter. the crown index (e.g., hrdlička, 1923; thomsen, 1955; hillson, 1996) is a measure of crown shape based on the two commonly-measured crown dimensions, namely maximum mesiodistal and buccolingual diameters. this index is buccolingual crown size expressed as a percentage of mesiodistal crown size, bl md     x 100 a tooth with a large crown index has a buccolingually broad crown relative to its mesiodistal length; conversely, a small crown index means the tooth is narrow in relation to it length. analysis relied on analysis of variance (winer et al., 1991; sokal and rohlf, 1995). initial tests used two-way anova to evaluate race and sex differences, but sex differences are uncommon, so a one-way model was used to simplify presentation and recover the degrees of freedom. statistical significance was set at the conventional level of alpha = 0.05, and no correction was made for multiple comparisons. results applying two-way anova to the 10 tooth types (table 1) disclosed that sex differences are uncommon (only the lower first molar), but that black-white race differences are prevalent. indeed, of the 10 tooth types, only the maxillary canine fails to exhibit a significant black-white difference in the crown index. consequently, “sex” was dropped from the model, and the one-way anova results (table 2) produce the same interpretation, namely that the crown index is consistently lower in blacks than whites— that the crowns are mesiodistally longer in blacks than fig. 1. plot of the crown index, by race and tooth type (sexes pooled). the index is significantly lower in blacks for all tooth types excepting the maxillary canine. only the maxillary molars exhibit indices greater than one (where bl breadth is larger than md length). primary tooth crown indices 86 whites relative to their buccolingual crown widths. in terms of explained variance (r2), the largest f-ratio is for the mandibular first molar (fig. 1), where “race” accounts for 17% of the total variance. this percentage is less than 10% for the other tooth types. the patterns of crown indices among tooth types are illustrated in figure 2. the patterns differ between arches, notably because of the high values for the two maxillary molars, which are the only teeth with indices above 100% (bl breadths > md lengths). based on paired t-tests, the index is significantly higher for the upper lateral incisor than the adjacent central incisor both in blacks and whites (p < 0.0001). comparably, the index is significantly lower for the upper second molar than the first (p < 0.0001) the pattern is less consistent in the mandible. evaluated with paired t-tests, the crown index for i1 and i2 is virtually identical in blacks (p = 0.996), but there is a significant i1-to-i2 drop in the white sample (p = 0.03). between the lower molars, blacks exhibit a significant m1-to-m2 increase in the index (p = 0.0003) whereas this gradient drops significantly in whites (p = 0.04). as with any ratio, there are at least three possibilities for the race differences in crown indices: the numerators may differ between groups, the denominators may differ, or both. all 20 of the tooth dimensions were surveyed (table 3), and none of the 10 buccolingual dimensions was significantly different between blacks and whites. in contrast, 7 of the 10 mesiodistal dimensions were significantly different between these two groups. the interpretation of differences in the crown index between blacks and whites is, thus, greatly simplified; the differences in the crown indices are due to blacks possessing teeth that are disproportionately long in relation to their buccolingual breadths. discussion the crown index has historically been used to characterize the width-length relationship of the molars, but there is no conceptual reason for this. the index is equally informative across all tooth types (e.g., garciagodoy and townsend, 1984; foster and harris, 2009). it was unanticipated that the crown indices would be statistically identical between boys and girls (table 1) because this suggests that sexual dimorphism does not measurably influence tooth shape. the level of dimorphism is less in the primary than the permanent dentition (harris and lease, 2005), but it certainly exists, and some authors (devito and saunders, 1990; zadzińska et al., 2008; adler table 3. results of two-way anovas testing for race and sex differences in crown size race sex interaction adjusted tooth f p f p f p percent r2 mesiodistal maxillary i1 8.33 0.0046 20.54 <0.0001 1.95 0.1652 19.87 i2 8.81 0.0035 17.97 <0.0001 7.62 0.0065 15.63 c 1.15 0.2842 19.20 <0.0001 0.00 0.9759 11.92 m1 14.32 0.0002 17.20 <0.0001 0.85 0.3581 15.27 m2 11.77 0.0008 8.35 0.0043 0.30 0.5874 11.09 mandibular i1 8.31 0.0048 9.15 0.0031 0.05 0.8219 16.28 i2 0.18 0.6714 1.18 0.2802 1.28 0.2595 2.60 c 0.59 0.4428 8.85 0.0033 0.31 0.5780 6.07 m1 23.59 <0.0001 6.20 0.0137 2.39 0.1240 16.94 m2 15.36 0.0001 13.27 0.0004 0.39 0.5348 15.79 buccolingual maxillary i1 0.74 0.3898 15.62 0.0001 2.22 0.1385 10.89 i2 0.75 0.3868 18.99 <0.0001 7.60 0.0066 9.76 c 1.03 0.3119 9.27 0.0027 0.24 0.6265 4.87 m1 2.60 0.1087 1.92 0.1674 0.68 0.4105 2.52 m2 0.17 0.6809 4.77 0.0303 0.27 0.6030 2.75 mandibular i1 0.33 0.5676 3.80 0.0540 1.75 0.1888 7.46 i2 2.08 0.1518 2.09 0.1505 3.07 0.0822 8.27 c 4.18 0.0423 3.90 0.0496 0.21 0.6457 3.82 m1 2.61 0.1080 7.14 0.0082 0.75 0.3868 3.40 m2 0.18 0.6708 15.01 0.0001 0.01 0.9352 8.64 e.f. harris and b.d. barcoft 87 and donlon, 2010) have explored its use in estimating the sex of human remains in forensic settings. the present results suggest that, at least by this metric, the larger teeth of boys are isometrically enlarged versions of the crown shapes in girls. these results raise the issue of population differences: this study found essentially no evidence of sexual dimorphism in either the black or white sample. in contrast, margetts and brown (1978) study of yuendumu australians found that the indices of primary teeth tend to be higher in boys. garcia-godoy and townsend (1984), in contrast, found higher indices in girls in their sample of dominican mulatto (black-white) children. these population differences discount stereotypes that humans are monomorphic. early extrapolations to all groups (e.g., garn et al., 1967a,b) actually stemmed from the paucity of information on racial differences. nine of the 10 black-white comparisons by tooth type (table 2) are highly significant statistically. only the maxillary canine has the same shape relationship in the two groups. for all of the other tooth types, blacks have a significantly lower crown index. it is well appreciated that american blacks have larger crown dimensions than whites absolutely—both as regards the primary (e.g., vaughan and harris, 1992; anderson, 2005) and permanent (richardson and malhotra, 1975) dentitions—and the results here indicate that the groups also differ in their width-to-length relationships. interestingly, interpretation is greatly simplified when (table 3) it is noted that none of the buccolingual crown dimensions differs significantly. this shows that the lower crown indices seen in blacks are due to the mesiodistal dimension. the primary teeth in american blacks have smaller crown indices than whites because their tooth crowns are larger mesiodistally. all of the primary teeth are established and begin crown mineralization during the second trimester in utero (lunt and law, 1974), so whatever the causes of mesiodistally larger teeth in american blacks—such as up-regulation of mitotic rates—are initiated early in development. nothing is known about the primary teeth, but the permanent teeth form and emerge faster in blacks than whites (steggerda and hill, 1942; harris and mckee, 1990), even though the teeth are larger. making larger teeth in a shorter time suggests that the mitotic rates are faster; there seem to be no data suggesting that the quality of enamel or dentin differ between blacks and whites. hall et al. (2007) found that enamel was thicker in blacks than whites—which again suggests a difference in growth tempos—though the differences in enamel do not account for the larger overall crown differences. one might suppose that mesiodistally larger teeth would translate into a greater risk of crowding—where arch size (determined by the supporting basal bones) is inadequate for proper alignment of the larger teeth. in fact, dental crowding (inadequate arch size) is not more common in american blacks than whites (kelly and harvey, 1977; brunelle et al., 1996). on the contrary, the prevalence of interdental spacing is appreciably higher in blacks than whites. the lack of an increased risk of crowding is due to the disproportionately large arches in blacks (burris and harris, 1998). as ross-powell and harris (2001) show, this race difference is ostensible from early in the primary dentition. prior work in our lab (harris et al., 2001) suggest that differences in the crown sizes of american blacks and whites are primarily due to differences in size of the dental pulps. developmentally, size of the pulp is defined by the growth of the enamel epithelium—which, in the mature tooth, is the interface between the enamel and dentine— prior to mineralization. the present results suggest that growth of the premineralized tooth bud is different in blacks and whites—that growth favors the mesiodistal axis in blacks, creating a different crown shape. references cited adler cj, donlon d. 2010. sexual dimorphism in deciduous crown traits of a european derived australian sample. forensic sci int 199:29-37. anderson aa. 2005. dentition and occlusion development in african american children: mesiodistal crown diameters and tooth-size ratios of primary teeth. pediatr dent 27:121-128. anderson aa. 2006. occlusal development in children of african american descent. types of terminal plane relationships in the primary dentition. angle orthod 76:817-823. anderson aa. 2007. the dentition and occlusal development in children of african american descent. angle orthod 77:421-429. brunelle ja, bhat m, lipton ja. 1996. prevalence and distribution of selected occlusal characteristics in the us population, 1988-1991. j dent res 75:706-13. burris bg, harris ef. 1998. identification of race and sex from palate dimensions. journal of forensic sciences 43:959-963. dahlberg g. 1940. statistical methods for medical and biological students. london: george allen and unwin. devito c, saunders sr. 1990. a discriminant function analysis of deciduous teeth to determine sex. j forensic sci 35:845-858. edgar hj, hunley kl. 2009. race reconciled?: how biological anthropologists view human variation. am j phys anthropol 139:1-4. ferguson fs, macko dj, sonnenberg em, shakun ml. 1978. the use of regression constants in estimating tooth size in a negro population. am j orthod 73:68-72. foster cl, harris ef. 2009. discriminatory effectiveness of crown indexes—tests between american blacks and whites. dental anthropology 22:85-92. garcia-godoy f, townsend gc. 1984. crown indices of the deciduous teeth in dominican mulatto children. acta odondol pediatr 5:25-27. primary tooth crown indices 88 garn sm, lewis ab, kerewsky rs. 1967b. sex difference in tooth shape. j dent res 46:1470. garn sm, lewis ab, and kerewsky rs. 1967b. shape similarities throughout the dentition. j dent res 1967;46:1481. garn sm, sandusky st, nagy jm, trowbridge fl. 1973. negro-caucasoid differences in permanent tooth emergence at a constant income level. arch oral biol 18:609-615. garn sm, wertheimer f, sandusky st, mccann mb. 1972. advanced tooth emergence in negro individuals. j dent res 51:1506. hall ne, lindauer sj, tüfekçi e, shroff b. 2007. predictors of variation in mandibular incisor enamel thickness. j am dent assoc 138:809-815. hanihara k. 1976. statistical and comparative studies of the australian aboriginal dentition. university museum, university of tokyo, bulletin no. 11. harris ef, bailit hl. 1980. the metaconule: a morphologic and familial analysis of a molar cusp in humans. am j phys anthropol 53:349-358. harris ef, dinh dp. 2006. intercusp relationships of the permanent maxillary first and second molars in american whites. am j phys anthropol 130:514-528. harris ef, hicks jd, barcroft bd. 2001. tissue contributions to sex and race differences in tooth crown size of deciduous molars. am j phys anthropol 115:223-237. harris ef, lease l. 2005. mesiodistal tooth crown dimensions of the primary dentition: a worldwide survey. am j phys anthropol 128:593-607. harris ef, mckee jh. 1990. tooth mineralization standards for blacks and whites from the middle southern united states. j forensic sci 35;859-872. hillson s. 1996. dental anthropology. cambridge: cambridge university press. hrdlička a. 1920. shovel-shaped teeth. am j phys anthropol 3:429-465. hrdlička a. 1923. variations in the dimensions of lower molars in man and anthropoid apes. am j phys anthropol 6:423-438. infante pf. 1974. sex differences in the chronology of deciduous tooth emergence in white and black children. j dent res 53:418-421. keene hj. 1967. australopithecine dental dimensions in a contemporary population. am j phys anthropol 27:379-383. keene hj. 1979. mesiodistal crown diameters of permanent teeth in male american negroes. am j orthod 76:95-99. kelly je, harvey cr. 1977. an assessment of the occlusion of youths 12-17 years. united states public health service, vital and health statistics, series 11, no. 162. lunt rc, law db. 1974. a review of the chronology of calcification of deciduous teeth. j am dent assoc 89:599-606. macko dj, ferguson fs, sonnenberg em. 1979. mesiodistal crown dimensions of permanent teeth of black americans. asdc j dent child 46:314-318. margetts b, brown t. 1978. crown diameters of the deciduous teeth in australian aboriginals. am j phys anthropol 48:493-502. moss ml, chase ps. 1966a. morphology of liberian negro deciduous teeth. i. odontometry. am j phys anthropol 24:215-229. moss ml, chase ps. 1966b. morphology of liberian negro deciduous teeth. ii. arch dimensions and occlusion. am j phys anthropol 25:261-275. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 68:157-164. richardson er, malhotra sk. 1976. recent findings on the mesiodistal diameter of the crowns of the permanent dentition of american blacks. q natl dent assoc 34:4451. ross-powell re, harris ef. 2001. growth of the anterior dental arch in african-american children: a longitudinal study from 3-18 years of age. am j orthod dentofacial orthop 118:649-657. seipel c. 1946. variation in tooth position: a metric study of variation and adaptation in the deciduous and permanent dentitions. swed dent j 39:1-176. sokal rr, rohlf fj. 1995. biometry: the principles and practice of statistics in biological research, 3rd ed. san francisco: w.h. freeman and company. steggerda m, hill tj. 1942. eruption time among whites, negroes and indians. am j orthod oral surg 28:361370. thomsen s. 1955. dental morphology and occlusion in the people of tristan da cunha. results of the norwegian scientific expedition to tristan da cunha, 1937-1938, no. 25. oslo: det norske videnskaps-akademi. townsend g, richards l, hughes t. 2003. molar intercuspal dimensions: genetic input to phenotypic variation. j dent res 82:350-355. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, p 13-31. vaughan me, harris ef. 1992. deciduous tooth size standards for american blacks. j tenn dent assoc 72:30-33. winer bj, brown dr, michels km. 1991. statistical principles in experimental design. 3rd ed. new york: mcgraw-hill book company. zadzińska e, karasińska m, jedrychowska-dańska k, watala c, witas hw. 2008. sex diagnosis of subadult specimens from medieval polish archaeological sites: metric analysis of deciduous dentition. homo 59:175187. e.f. harris and b.d. barcoft 30 dental anthropology 2020 │ volume 33 │ issue 01 the tales teeth tell is an introduction to dental anthropology interwoven with its author’s own experience of research and discovery. it takes the considerable expertise in tooth histology and imaging methods of the author and embeds them in the larger world of tooth growth and development, detailing processes at both the cellular and population level, introducing avenues of research and the questions that face the field. professor tanya smith, now of griffith university, has had a remarkable career trajectory thus far, moving from her phd to prestigious fellowships at the max planck institute for evolutionary biology and the radcliffe institute at harvard university. her work has concentrated on advancing histological research through innovative imaging projects. this work involved long-term collaborations with paul tafforeau on synchrotron imaging of dental tissue, and through other methods of understanding early life tooth growth and development, such as the collaborations with dental researchers manish arora and christine austin looking at breastfeeding signals in tooth chemistry. her considerable expertise in dental growth and development and its evolution in our lineage has allowed her to offer a uniquely bottom-up approach to introducing dental anthropology, specifically by introducing the structure and growth of dental tissues as a way to approach questions of import to primate evolution as well as health and well-being in modern human societies. the book is comprised of nine chapters, grouped into three sections covering major concepts in dental development, evolution, and what teeth reveal about behavior in addition to an introduction, conclusion, index, and a uniquely formatted ‘notes’ section that occupies a useful halfway house between endnotes (collected by chapter, though placed at the end of the text) and a formal bibliography. the flow of the book follows a path that might be expected from the author’s special interest in dental structures. from chapter one we are immediately immersed in the complications of tooth biology, and while it is a daunting subject, the explanations are clear and concise. chapter two ties the structure of teeth to their development, while chapter three introduces the obverse of development in the form of growth disruptions and other features that reveal information about past lives such as carious lesions and malocclusion. chapter four begins the section on evolution, and we follow from fish through to hominin fossils by chapter five, which presents major arguments in hominin dental evolution (enamel/dentine thickness, size reduction) without being overly dogmatic. chapter six is perhaps the most interesting of the book, as it deals directly with the author’s subject of expertise, dental growth and development and the evolution of our species. the potential for new research in this area is immense, and the treatment here allows the reader to sense this. the final section is devoted to how dental anthropology can be used to examine behavior, with a nuanced discussion in chapter seven of what is (and isn’t) possible to say about past diet from teeth alone. while some of the discussion of the interpretation of barium stable isotope ratios as a weaning signal may eventually need to accommodate a wider range of elements to fully describe the trophic dietary processes revealed in dental tissue, this chapter clearly introduces fascinating and important applications of developmentally focused dental anthropological research. chapter eight continues with an upto-date discussion of the possibilities and pitfalls of biomolecular analyses as well as a very brief look at a variety of other subjects including morphology, wear, and sexual dimorphism. finally, chapter nine introduces the many ways teeth can be culturally modified, such as for display, with wear making a reappearance in the discussion. in closing, smith considers the future of teeth, offering a glimpse into the changing evidence of life history and adaptation to new lifestyles teeth reveal. the main strength of this book is that it asks the reader to begin at the beginning by foregrounding the developmental process of dental tissues, an approach that provides a solid foundation for dental anthropological research. in addition, it addresses several of the bugbears of dental anthropology, with very careful attention paid to theories which may have been taught as current for decades but within narrow subfields are being challenged, such as the book review the tales teeth tell. by tanya m. smith. mit press. 2018. 296 pp., $29.95 (hard cover). isbn: 978-0262038713. 31 dental anthropology 2020 │ volume 33 │ issue 01 idea that molar eruption in primates maps directly onto life history stages such as age at weaning or reproduction, or that the dental (and facial) reduction seen in our species in the last ~10,000 years is completely understood. it is a comprehensive and detailed introduction to dental anthropology, so much so that it is possible to wonder if the work is targeted to a public or professional audience. it is of considerable utility to the advanced student or nonspecialist seeking to broaden their knowledge, but the author’s willingness to share her love of anthropological science and discovery suggests a hope that it will fall into the hands of someone who does not (yet) know the fascination of dental anthropology. it speaks to the depth of subject matter in the field that smith’s foray into accessible writing about dental anthropology comes so close on the heels of the excellent volume by peter ungar but still offers much of unique interest. while some basic descriptions of tissues or processes might repeat those in other texts, smith’s volume maintains a distinctive voice while uniquely presenting a cell–up perspective on dental tissues. a nuanced understanding of the processes of tooth development allow the author to relay the complicated and, frankly, difficult to digest, patterns of enamel and dentine formation in a comprehensible way. very few undergraduates come to dental anthropology with a developmental perspective, but given the potential for research in this area to answer big questions about evolution and behavior, this seems like a timely reframing of what is necessary for the anthropologist to know about teeth. it is a rather large ask to take microhistology and make it into something that inspires wonder, but i do hope that of the many anthropology students who will eventually pick up this book at least a few catch the sense of excitement and possibility smith so clearly feels for the tales teeth can tell. brenna ryan hassett institute of archaeology university college london muzall et al. 2014.3 8 dental anthropology 2014 │ volume 27 │ issues 01 and 02 2014 dahlberg award winner: the effects of dietary toughness on occlusopalatal variation in savanna baboons evan muzzall 1 , ryan m. campbell 1 , meadow campbell 1,2 , and robert s. corruccini 1 1department of anthropology, southern illinois university, carbondale, il 62901 2department of anatomy, southern illinois university school of medicine, carbondale, il 62901 abstract this study investigates the relationship between dietary toughness and craniofacial variation in two groups of savanna baboons. standard craniofacial and malocclusion data were collected from a captive, soft-diet experiment group (n=24) and a sample of wild-captured baboons, raised on tougher, natural foods (n=19). we tested the hypothesis that in the absence of normal masticatory stress experienced during the consumption of wild foods, the captive baboons would exhibit higher levels of facial and dental structural irregularities. principal component analysis indicates separation of the two samples. the soft-diet sample exhibits significantly shorter palates, greater variability in palate position, and higher frequencies of occlusal irregularities that correlate with the shorter palates. results offer further support that long-term dietary chewing stresses have a measurable effect on adult craniofacial variation. keywords: diet, occlusopalatal variation, savanna baboons correspondence to: evan muzzall, dept. of anthropology, southern illinois university, faner building, rm. 3525, 1000 faner dr., carbondale, il, 62901 email: muzzall@siu.edu telephone: (618) 536-6651 malocclusions are the improper growth, positioning, and/or alignment of the teeth and jaws that lead to irregularities in occlusal surface contact and abnormalities of the surrounding bony structures. these deviations are due to multiple factors, but the reduced masticatory demands of modern diets have shown considerable influence (corruccini, 1984; 1999; corruccini et al., 1983; corruccini and lee, 1984; varrela, 1990, 1992, 2006; evensen and øgaard, 2007). notably, alterations in the proper growth trajectories of these areas due to decreased chewing forces are not unique to humans. by controlling for diet, laboratory animal studies have contributed to a broader understanding of occlusofacial variability (beecher and corruccini, 1981a, b; corruccini and beecher, 1982; larsson et al., 2005; grünheid et al., 2009; jašarević et al., 2010; ravosa et al., 2010; dias et al., 2011; makedonska et al., 2012). this study expanded on the research of corruccini and beecher (1984), who found reduced facial growth, decreased structural correlations, narrower faces, and more occlusal irregularities in savanna baboons fed a soft diet. using the same soft-diet sample as corruccini and beecher (1984), but a different research design and a wild comparative sample, the present study contrasted craniofacial and occlusal data between two groups of savanna baboons fed diets that differed in their mechanical properties. this study tested the hypothesis that in the absence of natural food consumption, the soft-diet baboon sample would exhibit higher levels of craniofacial variation due to their reduced chewing demands. materials and methods the soft-diet experiment group consisted of 24 male papio cynocephalus skulls housed at southern illinois university carbondale. as part of a biomedical study in the 1970s, these individuals were fed "a very soft, atherogenic diet consisting of cholesterol, lard, butter, egg yolks, and powdered chow" for the last 27 months of their dental maturation (corruccini and beecher, 1984:136). eighteen male p. anubis and one male p. cynocephalus individual housed at the field museum of natural history were selected to be the wild-diet control sample because of their wild african origin. although their exact diet was not known, their natural wild foods consist of grasses, roots, plants, leaves, bark, gums, seeds, fruit, berries, corn, small invertebrates, and even sheep and goats (post, 1981; barton, 1993; wahungu, 1998; akosim et al., 2010; johnson et al., 2012). visually, all individuals were dentally mature and had erupted third molars to suggest ages around 6-8 years (phillips-conroy and jolly, 1988). 9 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 members of genus papio are possibly populations of a single species and are sometimes referred to as papio hamadryas cynocephalus and p. hamadryas anubis to reflect this subspecies distinction. p. cynocephalus and p. anubis have been known to interbreed (samuels and altmann, 1986; alberts and altmann, 2001; charpentier et al., 2008; tung et al., 2008) despite geographical distinctions in their genetic compositions (williams-blangero et al., 1990; zinner et al., 2013). further, frost et al. (2003) noted cranial morphological clinal organization of genus papio in africa. northern baboons (like p. anubis) exhibit broader, less flexed crania and rostra compared to the southern forms (such as p. cynocephalus) that display inferiorly flexed and narrower crania and rostra (frost et al., 2003:1056, 1069). because of their clinal organization and similar environments, general shape differences between these two groups observed by frost et al. (2003) likely reflect genetic differences. linear measurements consisted of standard craniofacial measurements (moore-jansen et al., 1994) and posterior airway maximum lengths and breadths (fig. 1, table 1). these data were recorded using spreading and sliding mitutoyo calipers calibrated to 0.01mm. principal component analysis (pca) was used to identify measurement loadings responsible for driving the observed variation. pearson's product-moment correlation coefficient was used to analyze the strength of correlation between measures identified by the pca. occlusal data (table 2) consisted of molar class relationships (angle, 1899), posterior crossbite, rotations, displacements, and incisor overbite and overjet following the summation in harris and corruccini (2008). for the purposes of our study, we reduced occlusal scores to a score of 0 for normal occlusion and 1 for any deviation from normal occlusion in each category. these values were summed to estimate the magnitude of occlusal irregularity for each individual, and significant differences between the samples were calculated using a mann-whitney u test. spearman's rank correlation coefficient tested for associations between relevant linear measures and occlusal scores. to attempt to account for potential variation in body size, shape ratios were calculated by dividing all linear measurements by foramen magnum breadth (simplified from area calculations found in radinsky, 1967; gould, 1975). the raw and scaled datasets produced highly similar results so that the data quality appears to be high, and only the scaled data are reported here. statistical analysis was conducted by rmc using the r project for statistical computing (r core team, 2013) and past: paleontological statistics software (hammer, harper, and ryan, 2001). results the pca results indicate that the combined first two principal components account for 81% of variation within the sample (fig. 2). the first principal component (pc1) indicates a size increase, primarily in the measures with the highest loadings, along that axis (fig. 3). there was clear separation between the wild-diet (maroon circles) and softdiet (blue circles) samples primarily along the second principal component (pc 2). the loadings for pc 2 (fig. 3) suggest that palate length (pal) and incisivion (most distal point in the incisive foramen) to basion (ifb) distance contributed most to variation along this axis. importantly, the single wild-diet p. cynocephalus (red circle) groups with the wild-diet p. anubis sample rather than the soft-diet p. cynocephalus sample, which suggests that the variation along fig. 1. illustration of relevant linear measures, palate length (pal) and incisivion to basion (ifb). 10 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 measure description mwcond mediolateral width of the mandibular condyle taken at the longest ml axis mlcond maximum ap length of the mandibular condyle, perpendicular to mwcond mdc maximum depth of the mandibular corpus from the superior edge of the alveolar mwcorp maximum width of the mandibular corpus from the labial to lingual side of the mandibular corpus at the midpoint of m1 mmdw maximum mandibular arch width at m1 taken on alveolar bone with calipers at the midpoint of lm1 and rm1 nmdw minimum mandibular arch width at m3 taken on the alveolar bone with calipers at the midpoint of lm3 and rm3 mandl mandibular length from the anterior point of projection on the alveolar bone of the mandible to the most posterior projection of the mandibular condyles (infradentale to condylion) mmw maximum maxillary arch width taken at the widest point of the alveolar bone on the maxilla regardless of field or adjacent tooth nmw minimum maxillary arch width at m3 taken on the alveolar bone (lingual surface) at the midpoints of lm3 & rm3 nsb minimum snout breadth between l & r maxilla, with calipers in the fossae pal the length of the palate measured from prosthion to the plane of the posterior projection of the maxilla (using a rubber band to delineate the posterior border) ifb from the most posterior point on the incisive foramen to basion (incisivion was estimated in poorly mascerated soft-diet individuals) pab the greatest medio-lateral breadth of the posterior airway, taken with the calipers held just posterior to the palate pah the anterio-posterior length of the internal nares, from the posterior margin of the palate to the anterior margin of the opening bzb the widest breadth across l & r zygomatic arches (zygion to zygion) fb the breadth of the frontal bone across brows fmw the medio-lateral breadth of the foramen magnum, measured from within the margins of the occipital with the “inside” arms of the caliper table 1. metric variables pc 2 is not the result of genetic differences. a two-sample t-test demonstrates that mean differences in pal were significantly smaller (p<0.000), and an f statistic indicates that ifb was significantly more variable (p<0.010) in the soft-diet sample (fig. 4, table 3). again, the bivariate plot of pal and ifb (fig. 5) implies that the wilddiet p. cynocephalus individual groups with the wild-diet p. anubis group, as a this is a reflection of the pca measures responsible for driving the observed variation. although a pearson's correlation coefficient for the soft-diet group (r=0.752) was only slightly lower than the wild-diet sample (r=0.780), results suggest that the soft-diet sample displays significantly shorter palate lengths relative to ifb distances. a mann-whitney u test (table 4) indicates that the softdiet sample exhibits significantly greater overall occlusal scores than the wild-diet group. spearman’s correlation coefficient (table 5) demonstrates a relatively weak yet significant (p<0.050) negative correlation between pal and occlusal scores and suggests that occlusal patterns become more variable as palate length reduces. discussion the hypothesis that the soft-diet baboon sample would exhibit higher levels of craniofacial variation due to decreased masticatory loading during ontogeny is supported. specifically, the soft-diet group exhibits greater occlusopalatal variation. the single wild-diet p. cynocephalus offers support that our results are not the mere reproduction of clinal shape differences of genus papio as noted by frost et al. (2003). although genetics undoubtedly play a considerable role (carlson, 2005; harris, 2008; koussoulakou et al., 2009), our study supports the potential for environmental factors to alter developmental trajectories. incisivion (mew, 1974; frost et al., 2003) should be utilized when investigating basicranial flexion. by using incisivion to construct multivariate ratios, it may be possible to test for the functional and taxonomic significance of the palate's effect on basicranial flexion (corruccini, 1978; oxnard, 1983). through dietary manipulation of living animals, radiographs could be used to investigate the relationships between ontogenetic shape changes, adult cranial form, allometric scaling, heterochrony, and differential 11 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 measure description anterior overjet the maximum distance between the most inferior point on the upper central incisors, and the most superior point on the lower central incisors anterior overbite the maximum distance between the labial surface of the lower central incisors and the labial surface of the upper central incisors posterior crossbite the buccolingual interrelationship between upper and lower first molar antagonists normal occlusion the buccal cusp of the upper molars overhang the lower buccal cusps, with the lowers reaching proper centric occlusion buccal crossbite the upper molars are atypically buccally located, such that the lowers do not reach proper centric occlusion lingual crossbite the upper molars are atypically lingual, such that the buccal cusps of the uppers do not overhang the lowers buccal segment relationship the interrelationships between the upper and lower first molars in the parasagittal plane class 1 the mesiobuccal cusp of the m1 is parasagittal to the buccal groove of m1 class 2 the mesiobuccal cusp of m1 is mesial to the buccal groove of m1 class 3 the mesiobuccal cusp of m1 is distal to the buccal groove of m1 rotation refers to a tooth in its normal position in the dental arcade but rotated about its long axis. the sum of rotated teeth are recorded for each side. recorded for both maxilla and mandible 0 unrotated 1 rotated < 45° 2 rotated > 45° displacement refers to a tooth that is out of ideal alignment. the summed value is recorded. recorded for both maxilla and mandible 0 not displaced 1 displaced < 2mm 2 displaced > 2mm table 2. occlusal variables growth (frost et al., 2003; leigh, 2006; trenouth and joshi, 2006). this could broaden allometric understanding, as gilbert (2011) reminds us that a large percentage of shape information is lost during allometric correction, and our results suggest that masticatory behavior also confounds shape analyses. these implications are also important for humans. many authors have used the hunter-gatherer/agricultural transition to illustrate how changes in dietary selective pressures produced skull morphologies able to cope with new masticatory functional demands (carlson, 1976a, b; carlson and van gerven, 1977; hinton and carlson, 1979; paschetta et al., 2010). clinically, haskell et al. (2009) noted correlations between snoring, sleep apnea, and the structures of the face and mouth. however, this study cannot conclude about the taxonomic significance of airway dimensions in the two samples specifically, nor the relationships between dental variation and airway dimensions in general. there could be multiple reasons why smaller airway dimensions were not found in the soft-diet group. although the tight confines of the airway's location could have prevented the caliper arms from accurately touching the landmarks, there also exists the possibility that there does not exist significant morphological differences in this area. anthropologically, it should be remembered that diet influences our reconstructions of biodistance, phylogeny, and taxonomy whether we account for it or not. eshed et al. (2006) and halcrow et al. (2013) rightfully remind us that simple linear relationships between diet and the denti12 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 fig. 2. pca on scaled data. maroon circles = wild diet sample; blue circles = soft diet sample; red circle = the single wild-diet p. cynocephalus. fig. 4. boxplot for scaled data. wd = wild-diet sample; sd = soft-diet sample. pal = palate length; ifb = incisivion to basion. fig. 3. loadings for pc1 (top) and pc2 (bottom). note the inverse relationship between pal and ifb for pc2. 13 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 n x̅ sd f p t p pal wd 18 1.12 0.07 1.35 0.500 8.49 2.16e-10** pal sd 23 0.94 0.06 ifb wd 18 1.46 0.08 3.668 0.008* -0.13 0.90 ifb sd 23 1.47 0.15 table 3. summary statistics for relevant linear measurements scaled for body size *significant at p<0.010, **significant at p<0.000; wd = wild-diet sample, sd = soft-diet sample; pal = palate length, ifb = incisive foramen to basion n median u p occlusal wd 19 0 122 0.035* occlusal sd 20 1 table 4. mann-whitney u test for wild-diet and soft-diet occlusal scores *significant at p<0.050 r’s p pal + occlusal -0.3782 0.017* ifb + occlusal -0.2260 0.172 table 5. spearman correlation for relevant linear measures and occlusal scores *significant at p<0.050 fig. 5. biplot showing the relationship between pal and ifb. maroon circles = wild-diet sample; blue circles = soft-diet sample; red circle = the single wild-diet p. cynocephalus. tion should not be assumed as the ambiguity of genetic, environmental, and cultural influences have the potential to produce a multitude of skeletal adaptations and alterations. by expanding on the research of corruccini and beecher (1984), we were able to demonstrate that a variety of research designs can strengthen discussions about the gene-environment interaction and other complex anthropological topics. luckily, a stronger understanding of genetic influences will better contextualize environmental factors of phenotypic variation. kuang et al. (2013) have documented the involvement of regulatory genes in mice with long-term, laboratory induced malocclusions. new discoveries such as this continue to enable anthropology to pioneer explanations of observed skeletal variation. acknowledgements our gratitude is owed to bill stanley, lawrence haney, and anna goldman at the field museum of natural history (division of mammals) for access to the wilddiet sample. thanks to the southern illinois university carbondale department of anthropology for providing the soft-diet sample. jeremiah e. scott is thanked for providing helpful comments on the manuscript. 14 occlusopalatal variation in baboons dental anthropology 2014 │ volume 27 │ issues 01 and 02 literature cited akosim c, joseph j, egwumah po. 2010. assessment of feeding behavior of baboons (papio anubis) in hong hills adamawa state, nigeria. j res forest wldl env 2:60-72. alberts sc, altmann s. 2001. immigration and hybridization patterns of yellow and anubis baboons in and 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masticatory function and post-pleistocene evolution in nubia. am j phys anthropol 46:495-506. carlson ds. 2005. theories of craniofacial growth in the postgenomic era. semin orthod 11:172-183. charpentier mje, tung j, altmann s, alberts sc. 2008. age at maturity in wild baboons: genetic, environmental, and demographic influences. mol ecol 17:2026-2040. corruccini rs. 1978. morphometric analysis: uses and abuses. yrbk phys anthropol 21:134-150. corruccini rs. 1984. an epidemiologic transition in dental occlusion in world populations. amer j orthodontics 86:419-426. corruccini rs. 1999. how anthropology informs the orthodontic diagnosis of malocclusion's causes. lewiston: edwin mellen press. corruccini rs, beecher rm. 1982. occlusal variation related to soft diet in a nonhuman primate. science (new series) 218:74-76. corruccini rs, potter rhy, dahlberg aa. 1983. changing occlusal variation in pima amerinds. am j phys anthropol 62:317-324. corruccini rs, beecher rm. 1984. occlusofacial 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and environment for statistical computing. r foundation for statistical computing. vienna, austria. http://www.rproject.org radinsky lb. 1967. relative brain size: a new measure. science 155:836-838. ravosa mj, ning j, costley db, daniel an, stock sr, stack ms. 2010. masticatory biomechanics and masseter fiber-type plasticity. j musculoskelet neuronal interact 10:46-55. samuels a, altmann j. 1986. immigration of a papio anubis male into a group of papio cynocephalus baboons and evidence for an anubis-cynocephalus hybrid zone in amboseli, kenya. int j primatol 7:131138. trenouth mj, joshi m. 2006. proportional growth of craniofacial regions. j orofac orthop 67:92-104. tung j, charpentier mje, garfield da, altmann j, alberts sc. 2008. genetic evidence reveals temporal change in hybridization patterns in a wild baboon population. mol ecol 17:1998-2011. varrela j. 1990. effects of attritive diet on craniofacial morphology: a cephalometric analysis of a finnish skull sample. eur j orthod 12:219-223. varrela j. 1992. dimensional variation of craniofacial structures in relation to changing masticatoryfunctional demands. eur j orthod 14:31-36. varrela j. 2006. masticatory function and malocclusion: a clinical perspective. semin orthod 12:102-109. wahungu gm. 1998. diet and habitat overlap in two sympatric primate species, the tana crested mangabey cercocebus galeritus and yellow baboon papio cynocephalus. afr j ecol 36:159-173. williams-blangero s, vandeberg jl, blangero j, konigsberg l, dyke b. 1990. genetic differentiation between baboon subspecies: relevance for biomedical research. am j primatol 20:67-81. zinner d, wertheimer j, liedigk r, groeneveld lf, roos c. 2013. baboon phylogeny as inferred from complete mitochondrial genomes. am j phys anthropol 150:133-140. harris 2009b.4 21 dent 3:204-215. rajab ld, hamdan mam. 2002. supernumerary teeth: review of the literature and survey of 152 cases. int peadiatr dent 12:244-254. schulze ch. 1987. anomalien und mißbildungen der menschlichen zähne. quintessenz vol 94-101. schwerz f. 1916. morphologische untersuchungen an zähnen von alamannen aus dem v. bis x. jahrhundert. arch anthropol 15:1-43. silva am, silva al. 2007. unilateral fusion of two primary mandibular teeth: report of a portuguese archeological case. dental anthropology 20:16-18. the case report by gyongyi szabó and colleagues (dental anthropology 2009;22(1):18-21) raises several interesting issues. a challenging aspect of examining teeth—which are the end-products of foregone cascades of developmental events—is that interpretations of the formative processes that produced the final form are conjectural, and there is no way to test assumptions. experience and encountering repeated occurrences of a dental condition are helpful, but they are hardly infallible. terminology a fundamental consideration raised by this case report is terminology. specifically, what constitutes a supernumerary tooth? or, for that matter, what is a tooth? i looked through a number of recent papers on hypoand hyperdontia, and there is a striking absence of an operational definition of what a “tooth” is. recognition of a tooth evidently is considered so obvious (or so difficult) that it doesn’t warrant a definition. it seems that mineralized tissues (dentin, enamel) are an important criterion, but this is simply because most studies nowadays are radiographic surveys, so premineralized tissues are undetectable. however, dental histologists are quite comfortable that the premineralized structures seen in the bud, cap, and bell stages constitute a “tooth,” so mineralization cannot be an essential feature. popular textbooks on dental anatomy (e.g., zeisz and nuckolls, 1949; kraus et al., 1969; ash, 1993) launch right into descriptions of the morphology of each tooth type, apparently supposing that a definition would be superfluous. the normally-occurring teeth (20 primary, 32 permanent) are all characterized by a *correspondence to: edward f. harris, department of orthodontics, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu smith p. 2004. middle bronze age ii burials at sasa, upper galilee (tomb 1 and graves 37, 39). ’atiqut 46:35-43. stafne ec. 1932. supernumerary teeth. dental cosmos 74:653-659. sutton pr. 1985. tooth eruption and migration theories: can they account for the presence of a 13,000-yearold mesiodens in the vault of the palate? oral surg oral med oral path oral radiol endod 59:252-255. commentary: supernumerary teeth edward f. harris department of orthodontics and department of pediatric dentistry, university of tennessee, memphis fig. 4. a supernumerary tooth in the enlarged incisive foramen of a prehistoric american indian. ectopic teeth tend to be in the vicinity of the dental arches, but they may form or migrate elsewhere. joined premolar teeth crown (enamel, dentin, pulp) and one or more roots (cementum, dentin, pulp), but it is not clear whether a dental element must have all of these features to achieve “toothness.” also, sizes of the crown and root do not seem to be important criteria. one might claim that teeth obviously are found in the two dental arches, but locality is not definitive given the extraordinary 22 places a “tooth” can occur. fig. 4‡ is an example where a supernumerary incisor (probably a mesiodens) is hidden in the subject’s incisive foramen. the literature describes ectopic teeth located in various midface regions, such as the nasolacrimal duct (alexandrakis et al., 2000), the bony orbit (savundranayagam, 1972), and the eyelid (subramaniam et al., 1966). many of us were taught in an embryology class or elsewhere about dermoid cysts (e.g., shafer et al., 1983), which contain well-differentiated skin and other identifiable tissues (e.g., hair, sweat glands, bone, cartilage, etc.), including teeth. these “teeth” commonly are of identifiable types, often incisors and premolars, which shows that the same complex of biochemical signals that produce a tooth in a dental arcade can perform just as well elsewhere in the body (e.g., jernvall and thesleff, 2000). this is not surprising given the landmark embryological studies fig. 6. a cropped view of a panoramic radiograph of a subject with dentin dysplasia i, where root formation is severely restricted, so several of the teeth appear to be ‘root-less’ though they generally erupt normally. note the apical radiolucencies around several of the teeth, which is characteristic of this condition. also, the pulp chambers are obliterated and filled with dysplastic dentin. fig. 7. an exceptionally large tuberculum dentale is located on the subject’s right maxillary central incisor (arrow). large examples such as this with a free cusp often are labeled talon cusps because the appearance of an incisor with a labial and lingual cusp is reminiscent of a raptor’s claw (e.g., harris and owsley, 1991). based on size, this tubercle (with a free apex, a pulp horn, and an independent root) would qualify as a “tooth,” but it is not counted as such because (a) it developed from the cingulum of the parent tooth and (b) it is a fused feature of the incisor, sharing dentin and pulp. fig 8. radiograph of a compound odontoma in the maxillary midline. there are four ‘toothlets’ visible here, but it is unclear whether they should be labeled as four supernumerary teeth because of their petite size and absence of any crown-root morphology. even on x-ray, it is evident that these dental elements consist of enamel, dentine, and a pulp chamber. note how this tumor is preventing the subject’s right maxillary central incisor from erupting and how it maintains a severalmillimeter gap between the left central and right lateral incisor. radiograph courtesy of james e. turner. fig. 5. a mesiodens—a supernumerary tooth located between the maxillary central incisors—is common. note how this erupted mesiodens displaces the incisors. there is chipping of the occlusal border of the mandibular right central incisor because of the edge-toedge malocclusion. supernumerary incisors typically are single-cusped and conical with a single root. e.f. harris ‡figures 1-3 are those in published in the prior article by szabó et al. (2009). 23paramolar tubercles of growing implanted tooth buds in the globes of eyes of laboratory animals (e.g., yoshikawa and kollar, 1981). dermoid cysts occasionally occur in ovaries (e.g., mcginnis and parham, 1978; dick and honoré, 1985; liberis et al. 2008), which means they should be recoverable archeologically, though i’m unaware of any reference to them. a tooth does not have to be normal size or shape to be counted. diminutive elements, such as pegged and microdont teeth, are routinely counted. many authors include mineralized elements of any morphology, including “dental masses” of amorphic mineralized objects as found in odontogenic tumors, notably compound odontomas (e.g., shafer et al., 1983; owens et al., 1997). a supernumerary tooth in the maxillary incisor region is probably the most common sort of supernumerary tooth, and these are characteristically petite single-cusped, often conical teeth with a single root (fig. 5). once mineralized, a “tooth” normally has a crown and root, but there are exceptions: a primary tooth in which the root has been completely lysed as part of the exfoliation process is still considered a tooth. socalled root-less teeth (as in dentin dysplasia i; omim #125400) also are considered teeth, though roots can be quite abbreviated if present (fig. 6). size alone does not define a tooth. the lingual tubercle (talon cusp) in figure 7 is virtually as large as the incisor crown proper, but it would not be counted as a tooth because (1) it is developmentally a component of that incisor and (2) it has always been united with the incisor. at the other extreme, figure 8 shows a compound odontoma (de oliveira et al., 2001), where four distinct tooth-like ‘denticles’ are evident (with the normal but impacted central incisor apical to them). do these ‘toothlets’ qualify as teeth? they have fully-differentiated enamel and dentin, but no crown-and-root morphology. does a “tooth” need to be physically separate from others to be counted? this seems to be an important distinction implied in most studies (patterson, 1956; hershkovitz, 1967). for example, cusp-like cingular elements are not counted as teeth. tubercles, accessory cusps, and styles are considered parts of the main tooth. cingular elements can be fairly large, but they are almost invariably coalesced with the permanent tooth so there should be no misidentification. these include talon cusps on the incisors, tuberculum dentale on canines, carabelli’s cusps on the lingual of upper molars, and paramolar tubercles on the buccal aspect of upper and lower molars (scott and turner, 1997). all of these cingular elements normally are single-cusped, and they all have at most a single root (e.g., bolk, 1916). ambiguity arises when, apparently in rare instances, a dental feature becomes physically separated from the main tooth (dubuk et al., 1996). paramolar tubercles do occasionally achieve physical independence when large, and these meet criteria for a “tooth,” namely possession a crown (enamel), root (dentin), and a toothlike morphology (though simplified). overlooking the details of what constitutes a tooth, there are countless anthropological and clinical dental studies of abnormal tooth numbers—either the congenital absence of one or more teeth (hypodontia) or hyperdontia, an excess number of teeth (table 1). studies rarely press the definition of a tooth too closely; instead, wording is used such as: hypodontia is a deficit in the normal dental formula or hyperdontia is teeth in excess of the normal dental complement. fig. 9. a rare instance of bilateral fusion of the primary maxillary incisors (arrows). (most cases are unilateral.) fusion is confirmed by (a) the appearance of confluent tooth forms in each quadrant and (b) the ‘absence’ of independent lateral incisor teeth. both compound teeth are carious, but their shared enamel, pulp chambers, and root dentin are evident. radiograph courtesy of ann s. smith. table 1. operational definitions1 condition definition hypodontia congenital absence of one to five permanent teeth, generally excluding third molars. oligodontia absence of more than five teeth. the study may or may not exclude third molars. anodontia the complete absence of all primary and/or permanent teeth. the phrase “partial anodontia” (actually denoting hypodontia or oligodontia) is an oxymoron. hyperdontia presence of one or more teeth in excess of the species’ normal dental formula. 1partly from schalk van der weide (1992), reproduced in koch and thesleff (2001, p 261). 24 ontogeny the structure imaged in szabó’s figures clearly emanates from the premolar ’s buccal cingulum, and it shows developmental features in common with the tooth proper. as szabó et al. point out, there is a common pulp chamber, and the dentin is confluent between the tooth crown proper and the tubercle even though the tubercle has a well-developed root and pulp chamber (ohishi et al., 1999). it is most probable that this cingular feature was initiated by an enamel knot that, in the presumptive tooth, was located at the cusp apex, which has now (fig. 2) been abraded or is hidden by subsequent enamel deposition. a primary enamel knot is essential for a tooth’s formation, and laterforming secondary knots define each of a tooth’s cusps (e.g., jernvall et al., 1994; thesleff and jernvall, 1997; fig. 11. example of acquired concrescence between a second and third molar. roots of the two teeth are only united by cementum; there is no confluence of the underlying dentin. fig. 12. a paramolar tubercle on a maxillary left second molar. this tubercle (arrow) clearly is associated with the metacone rather than the molar’s paracone. bolk (1916) was very keen that paramolar tubercles were only derived from the paracone, though kustaloglu (1962) showed that this is untrue. fig. 13. a rare instance of two paramolar tubercles on a maxillary left second molar (arrow). (no cingular feature could be seen on the contralateral molar.) it appears that both tubercles are attached to the paracone (mesiobuccal cusp), though part of the distal tubercle crosses onto the metacone. note too a large, single paramolar tubercle on the paracone of the third molar. (paramolar tubercles rarely occur on permanent first molars.) fig. 10. radiograph showing fusion between a lower right central and lateral incisor (labial view). the lateral incisor is to the left of the figure. note the confluence of enamel and dentin between the crowns, though the pulp chambers and roots are separate. e.f. harris 25paramolar tubercles thesleff et al., 2001; obara and lesot 2007). i think it is notable that this cingular feature has a free apex that is occlusal to the developmental groove that distinguishes this tubercle from the tooth proper; this shows that the tubercle was developed as part of the differentiating morphology of the inner enamel epithelium because mineralization of dentin and enamel only proceeds in the occlusal-to-apical direction. these morphological components that are developmental parts of a tooth are not considered as separate teeth in tooth counts. ambiguous cases occur when a feature that is supposed to arise from an adjacent tooth’s cingulum is a physically separate dental element. bolk (1916) describes such cases in his classic paper on paramolar tubercles. either of two events may cause this, though the end products seem identical. one, the secondary enamel knot may have formed far enough away from the rest of the crown that the tubercle fissions off from the main tooth. this process of gemination (the word is derived from gemini, the star constellation of twins in greek mythology) is commonly described in dental texts on dental anomalies (e.g., pindborg, 1970; shafer et al., 1983), though actual examples of twinning are rare (e.g., gündüz and açikgõz, 2006; sivolella et al., 2008). twinning needs to occur during the cap or bell stage prior to crown mineralization, but the actual process is not understood. a critical feature defining geminated teeth is the presence of all of the other teeth in the morphogenetic field, so the twinned teeth clearly are not fused teeth (fig. 9). twinning requires duplication of the biochemical signals for tooth development within the dental sac. how this occurs seems to be a complete mystery at present. a traditional view is that two tooth-forming sites are stimulated to form close together in the dental lamina, which develops well before differentiation of the dental sac. it is supposed (pispa and thesleff, 2003) that, in normal dental development, a reaction-diffusion gradient develops around a formative teeth, where activators induce placode formation while negative regulators are intensified in interplacodal regions, which inhibit tooth formation and, thus, account for the orderly spacing of teeth. gemination might, then, be viewed as an exception where two sets of signals are preserved (or initiated) within the same dental sac that, then, gives rise to ‘twinned’ but fused teeth. geminated teeth (more common in the primary dentition) usually have a shared root and shared pulp cavity. the second process involves fusion, where two tooth buds begin to form independently, but, again, for reasons unknown, the formative teeth grow together. fusion typically starts at the cap or bell stage, so that the united teeth are combined along the lengths of their crowns and roots (fig. 10). fusion must involve the dentin, so the twinning is initiated during formation of the outer enamel epithelium (avery, 1994). the key feature for identification is that, counting the fused pair of elements as one, there needs to be a ‘missing’ tooth elsewhere in that morphogenetic field. this method of defining fusion is not thorough-going, because it supposes that development was disruptive enough to meld two tooth buds, but the same disruption did not cause agenesis of the “missing” tooth. reliance on the fused tooth morphology can be a help here, but convincing discrimination between fission and fusion may be impossible from inspection of the end product alone. a rare but classic case of tooth fusion is in people (and laboratory animals) with developmental midline problems, notably holoprosencephaly (hpe). hpe is the embryological failure of divisions of the head to form along the left-right, transverse, and/or craniocaudal axes (cohen, 2001). a remarkable dental consequence of this heterogenous group of anomalies can be a solitary median maxillary central incisor (smmci). nanni et al. (2001) provide a current review of this condition. experimental work shows that sonic hedgehog (shh), a signaling protein, is critical for the initiation of a tooth germ, probably by directing epithelial cell proliferation. in mice, the absence of shh can either prevent maxillary incisor formation (congenital absence) or cause these incisors to fuse. the maxillary central incisors begin formation close together and these tooth germs coalesce into a single symmetric central incisor (hardcastle et al., 1998). of note, the molar teeth are unaffected. alterations in the structure-function of shh provide the common etiology between the head (central nervous system) and tooth anomalies (cohen, 2004). aside from fusion and fission (gemination), yet a third situation occasionally occurs, namely concresence. pindborg (1970) valuably distinguishes between true concrescence and acquired concrescence. acquired concrescence occurs when two fully formed teeth are only united by the fluorescence of cementum (fig. 11). colby et al. (1961:42) note that two factors are required here, (1) the teeth, specifically the roots, of adjacent teeth fig. 14. a large parastyle on the maxillary right first premolar (line). a parastyle is a tubercle derived from the buccal cingulum of, in this case, the premolar’s paracone. (from kustaloglu, 1962.) 26 need to be in close proximity and (2) hypercementosis— excessive cementum deposition—unites the proximate roots. acquired concrescence is only distantly related to the fission and fusion of teeth because it occurs after tooth formation in contrast to being the consequence of some developmental aberration. in contrast, true concrescence involves confluence of the roots (dentin) of adjacent teeth, so it is a sort of fusion. paramolar tubercles numerous researchers have described “paramolar tubercles,” a term coined by bolk (1916:110). bolk surveyed some 30,000 skulls, so he is still a contender for the record number of identified tubercles. bolk argued that these tubercles on maxillary molars always develop from the mesial cusp. in fact, they can arise from the cingulum of either buccal cusp, and kustaloglu (1962) notes that they therefore should be labeled parastyles (mesiobuccal) or metastyles (distobuccal) depending on the cusp of origin. figure 12 shows a characteristic expression, where the tubercle developed buccal to the metacone, well distal of the lingual developmental groove that demarcates the union of the paracone and metacone. figure 13 shows a second molar with two equal-size paramolar tubercles, and it appears that both developed from the tooth’s paracone. such buccal tubercles are less common in the mandible, where, occasionally, they develop from the mesiobuccal cusp, thus making them protostylids (e.g., dahlberg, 1950). protostylids occur frequently enough that there is an asu dental plaque to score their size (turner et al., 1991; also see hlusko, 2007; skinner et al., 2008). paramolar features also can occur on the premolars. figure 14 is reproduced from kustaloglu’s article, showing a large tubercle on the facial aspect of the paracone (buccal cusp) of a maxillary premolar; this example is not dissimilar from the example described by szabó and coworkers (fig. 1). hyperdontia various ideas have been put forth over the years to explain why a supernumerary tooth might occur. some of these are noted in the reviews by rajab and hamdan (2002), botra et al. (2005), and elsewhere. these conjectures are of historical interest, but they comport poorly with current knowledge of the molecular control of tooth formation (e.g., mitsiadis and smith, 2006). a popular idea was atavisim, which is the idea that some phylogenetic ancestral condition (where more teeth were the norm) is being re-expressed. recall, for instance, that the baseline mammalian condition was at least 44 teeth (gregory, 1922; ji et al., 2002), and the human dental formula involves reductions of all tooth types except the canines (see review by peterkova et al., 2006). another conjecture was that one or more of the normally-occurring teeth splits (the dichotomy theory) to produce additional teeth (foley and del rió, 1970; taylor, 1972). another idea with some persistent credibility involves an extension of dental lamina at the end of the tooth row that is induced to form an additional tooth (saarenmaa, 1951), but this idea must include the reciprocal epithelial-mesenchymal inductions that promote tooth formation, “extra” dental lamina in itself does not cause teeth to form. such historical conjectures suppose that extra teeth are due to additional developmental activity, with the term “hyperactivity” often used in some vague sense to explain the over-production of teeth. recent evidence suggests that the opposite is true— that biochemical signaling is responsible for stopping the enumeration of teeth and is necessary for holding a species’ dental formula in check. a prime example is now known in some detail for humans: runx2 is a transcription factor that is key for osteogenic cell differentiation (ziros et al., 2008). mutations of runx2, which also is known as cbfa1, can cause cleidocranial dysostosis (ccd; omim #119600), the condition that is, perhaps, archetypical of hyperdontia in man (jensen and kreiborg, 1990; whittington and durward, 1996). people with ccd are likely to exhibit hyperdontia, especially in the premolar region (along with systemic problems of non-eruption due to a failure of bone resorption ahead of the erupting tooth). ccd shows the important role that runx2 normally plays in preventing excess budding of the dental lamina. however, hyperdontia in people with this autosomal dominant allele show variable expressivity, ranging from no extra teeth to cases with numerous extra teeth. the percentage of cases of ccd with hyperondia is around 1/5, showing that even in this archetypical condition, the formation of extra teeth is uncertain—presumably due to differences in allelic conditions and differences in genetic backgrounds. comparably, kantaputra and coworkers (2008) describe a single subject with unerupted teeth in the premolar-molar region evidently due to an inherited defect in trps1 causing gain of function. these authors suggest that this mutation mimics the dental phenotype of persons with runx2. murashima-suginami et al. (2007, 2008) show that upregulated bone morphogenetic protein (bmp) signaling causes supernumerary tooth formation in mice, notably in the incisor region (also see kassai et al. 2005). they interpret their experimental results as showing that odontogenic mesenchymal cells normally are killed off at the end of tooth rows because antagonists to bmp play a crucial role in controlling the enumeration of tooth buds. when an antagonist (termed ectodin or, synonymously, “uterine sensitization associated gene-1” or usag-1) is absent, bmp function is left uncontrolled, and the result is supernumerary tooth formation. that is, ectodin normally binds to bmp e.f. harris 27paramolar tubercles and inhibits its function; without inhibition, bmp can promote additional tooth sites. these studies show that extra teeth result from inadequate suppression of tooth-forming capacity, not the over-activity of tooth-promoting events. at this point in our understanding of toothpromoting conditions, it is unknown (a) how many genes (alleles, proteins) are responsible along the involved pathway of tooth development either to form an extra tooth or curtail formation of a normal tooth, (b) whether extra teeth at the end of the dental lamina (e.g., mesiodens, fourth molars) are due to the same causes as those within the tooth rows (such as the common extra premolars). other issues of interest involve (a) how and why human population differences in hypo and hyperdontia have developed, (b) what causes the persistent sex differences (hypodontia is more common in females; hyperdontia is more common in males) seen among humans, and (c) why the locations of missing and extra teeth differ among human groups. it also is effectively unknown how the environment affects any or all of these differences. it seems unlikely that there are simple or single, all-inclusive reasons for any of these issues. it is noteworthy that most supernumerary teeth are few in number within and among subjects, undersize and morphologically simplified. overall, it seems to be a major genotypic effort to increase tooth number, perhaps because of the large number of necessary steps needed to form a tooth. studies of supernumerary teeth in laboratory animals have certainly been informative (d’souza and klein, 2007). several studies show that perturbations of signalling molecules—either genetic knockouts or the overproduction of certain molecules—can cause the formation of extra teeth. for example, mice that over-express ectodysplasin (pispa et al., 2004) or underexpress antagonists to fgf (fibroblast growth factor; klein et al., 2006) can produce supernumerary teeth. but, it is important to question the relevance of these findings to humans. mice—the favored animal for studying tooth development—have a diastema in each quadrant where formation of lateral incisors, canines, and premolars is suppressed. however, several of these teeth initiate formation but are arrested and resorbed in the bud stage (peterkova et al. 2002, 2006) so the “rescue” of these tooth buds to permit them to develop into “supernumerary diastema teeth” is of considerable interest, but it is fundamentally different from the human condition where no primordia normally form. laterality another question raised by szabó’s case report is why their tubercle occurs unilaterally. conventional wisdom is that the genotypic information is the same in the left and right hemispheres of the body (polak 2003), so disparate phenotypes between quadrants are supposed to be the exception rather than the rule. researchers familiar with dental morphology recognize that, while left-right symmetry may be the norm, even striking exceptions are not hard to find. alvesalo and coworkers (1975) suggested that, for carabelli’s trait, expression on one tooth is always associated with some expression on the contralateral tooth, but this has not been my own experience. kustaloglu (1962) examined the osteological collections at the chicago national history museum (roughly 500 individuals) and found that paramolar tubercles tend to occur unilaterally more often than bilaterally, with a ratio of 18:4 among the permanent molars, though bilateral occurrences predominated in the primary dentition. dental anthropologists have embraced the idea that morphologic dental traits have a quasicontinuous mode of inheritance. supporting evidence stems primarily from animal studies (e.g., grüneberg, 1950, 1952) because few anthropological studies have subjects of known biological relationship (cf. saunders and mayhall, 1982; sjøvold, 1996). the quasicontinuous (qc) model of inheritance suggests that morphological dental traits are under polygenic control, but with a threshold below which the feature is not expressed (wright, 1934a,b; falconer, 1965). the question arises whether unilateral expression (fig. 1) is indicative of the subject’s genotype being close to the threshold. that is, subjects with a genotype for trait expression might be prone to expressing the trait unilaterally due to local environmental vagaries between the jaw’s quadrants. supposition is that genotypes farther above the threshold would be more likely to exhibit bilateral symmetry. this aspect of a qc model does not seem to have been tested for dental traits. overview in sum, my contention is that the case described by szabó and coworkers is a paramolar tubercle on the lower left first premolar, and, thus, should be labeled a protostylid. it is possible that this cingular feature developed from local trauma or infection, which would account for its unilateral expression, though that is sheer speculation. this tubercle is unquestionably a developmental feature of the premolar itself, as its union (shared enamel, dentin, and pulp cavity) precludes it being a supernumerary tooth. these comments are set forth in hopes of stimulating discussion among readers regarding this interesting case. literature cited alexandrakis g, hubbell rn, aitken pa. 2000. 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j 92:4-8. wright s. 1934a. an analysis of variability in number of digits in an inbred strain of guinea pigs. genetics 19:506-536. wright s. 1934b. the results of cross between inbred strains of guinea pigs differing in number of digits. genetics 19:537-551. yoshikawa dk, kollar ej. 1981. recombination experiments on the odontogenic roles of mouse dental papilla and dental sac tissues in ocular grafts. arch oral biol 26:303-307. zeisz rc, nuckolls j. 1949. dental anatomy. st louis: cv mosby company. ziros pg, basdra ek, papavassiliou ag. 2008. runx2: of bone and stretch. int j biochem cell biol 40:1659-63. turner 2010.6 33 sue haeussler passed away in november, 2009, at the age of 77, following a lengthy period of illness linked with alzheimer ’s disease. among the many reasons to remember sue, especially for the readers of this journal, is that she was editor of dental anthropology for 10 years (1991-2001), sharing editorship for her last issue with edward f. harris. during her tenure she advanced dental anthropology from being a short newsletter started by daa founder, m. yasar iscan, to a professional journal in ajpa style with peer-reviewed articles, book reviews, daa secretary and treasurer ’s reports, presidential addresses, and other interesting items. sue also promoted an international membership, paying out of her own pocket the annual dues for overseas scholars she knew who were in financial need. whoever reads this necrology will hopefully carry on sue’s helping our needy foreign dental anthropology colleagues. born on july 26, 1932, in philadelphia, the city where in 1954 she earned a b.a. degree in microbiology from the university of pennsylvania. as an undergraduate she was involved in various extra-curricular activities, notably photographic editor and feature writer for the pennsylvania news, experiences that she expertly applied years later to her meticulous guidance of dental anthropology. i first remember sue being in an introductory anthropology class that i taught in the large auditorium at the 1930s-style arizona state university agricultural building. the old, depression-era concrete building had as its only architectural excess, large fronting intaglio portraits of five or six famous scientists. only one was mostly hidden by a large tree—charles darwin. sue often came up excitedly after class with a ream of questions, especially about the issue of the colonization of the new world, a subject that would eventually become the heart of her massive doctoral dissertation and her grand odyssey in the former ussr. later, sue earned an m.a. in 1985 and a ph.d. in 1996, both in physical anthropology at our explosivelygrowing arizona state university campus in tempe. her dissertation data on dental morphology was collected traveling alone during a nine-month trip in the former ussr from december, 1990, to august, 1991. she was formally invited by scholars in various ussr academy of science institutes and universities housing archaeologically-derived human dental remains [st. petersburg, kiev (the ukraine), irkutsk, novosibirsk, tomsk, tbilisi (georgia), moscow, and krasnoyarsk], in that order, based on my examination of her more than 1,000 labeled color slides. her grit and stamina at a mature age (58) can be appreciated by the fact that despite unrelenting back pain, she walked resolutely, obituary alice “sue” marie frances haeussler (1932-2009) fig. 1. sue haeussler (left) and irkutsk state univeristy archaeologist, german i. medvedev, at the siberian village of mal’ta, south of lake baikal, march 31, 1991. the pair are standing on the frozen ground, beneath which (at about two meters depth) is the 21,000 yearold upper paleolithic site of the same name. the mal’ta archaeological site is world famous for its carved ivory female figurines, carved images of birds, stone blade knives, other artifacts, and mammoth bone shelters, all strongly suggestive of a link with european upper paleolithic culture. this link is further strengthened by the european-like permanent incisor and molar morphology of a child found “buried” at the site. sue and the author agree on the european character of the mal’ta teeth, making mal’ta the most eastern-known extension of cromagnon culture and people. photographer uncertain, but probably by ekaterina lipnina, medvedev’s archaeologist wife. 34 with the help of a stout wooden walking stick (fig. 1), even in the frigid winter months of her russian odyssey. her soviet research was aided by an irex fellowship and other sources. her speaking and reading knowledge of russian was gained with immense help from asu language professor, sanford couch. sue’s institute visits were greatly helped by the russians in her photos that i know also spoke excellent english, including serghei a. arutionov, moscow; alexander g. kozintsev, st. petersburg; alexander k. konopatski, novosibirsk; and the world renowned dental anthropologist, alexander a. zoubov, moscow. my own russian travel and research before and after that of sue’s has taken me to many of the institutes that she visited. everyone asked how she was, and had very kind words to say about her. she was an excellent ambassador for the united states. sue made an additional trip to russia that i know about. she participated in an international conference held in vladivostok. hence, she traveled across the totality of russia, from the baltic (st. petersburg), to the sea of japan (vladivostok). i know of few other graduate students, or even seasoned professors, who have undertaken such an odyssey, and everywhere left so much good will. in addition to her monumental two-volume dissertation (> 750 pages), sue also published a number of articles, abstracts, and presented posters, all at national and international meetings. a few of her more easily obtained titles are cited in the following bibliography. her dissertation lists several papers that were waiting publication or were in progress. as a dental morphology researcher, sue was a careful observer. where she and i studied the same dental collections in the ussr, we were concordant in >90% of our ranked scale and discrete observations. the prime rule governing the asu dental anthropology system of trait observation is: “when in doubt, never guess.” sue followed this rule religiously. in irkutsk, she found an example of donald morris’ “uto-aztecan” premolar. while her finding was only one of two examples ever recognized outside of the new world, there is absolutely no reason to doubt her observation. the gene(s) for this trait was present but very rare in northeastern asia, but its relatively frequent occurrence in american indians fits nicely with the views that there was founder ’s effect in the crossing of beringia, and more than one siberian migration to the new world since the trait has never been found in aleut-eskimo populations. sue’s thousands of other observations fit well with the hypothesis of a northeast asian origin of all native americans, and not an origin from central asia or europe as has been suggested on the basis of some archaeological considerations. i mention these finding to make two points: (1) very few archaeologists concerned with the colonization of the new world have traveled to russia to learn what archaeologists have found there. sue traveled to see the actual teeth of late pleistocene and holocene eurasian people. and, (2) few if any molecular geneticists (paleo or modern) read or acknowledge the findings of dental anthropologists. sue’s magnificent dental morphology study in the ussr will hopefully not be overlooked. as wife of a busy psychiatrist (william b. haeussler, m.d.), and mother, sue balanced her professional and personal life with admirable skill, compassion, and charm, always hiding her chronic back pain. her daily routine at asu often started at 4:00 a.m. lasting until well after dinnertime. she usually rode the bus from her home in phoenix to the asu campus in tempe. her time in transit was usually spent editing or reading articles, a number published in russian. peers and associates will greatly miss her, as will her family. at the risk of overlooking someone, sue’s close dental anthropology colleagues of whom i am aware of included edward f. harris; g. richard scott; diane e. hawkey; donald h. morris; shara e. bailey; c. loring brace; joel d. irish; scott burnett; christine lee; jaime ulinger; heather h. edger; kenneth a. r. kennedy; korri d. turner; christian r. nichol; john r. lukacs; alma j. adler; lorrie lincoln-babb; edwin f. crespo; stephen c. reichardt; thelma dahlberg; natalya i. khaldeyeva; alexander a. zubov; simon hillson; and the late daris r. swindler, albert a. dahlberg, and kazuro hanihara. sue had close professional colleagues in other branches of anthropology or science who will also miss her. again, those whom i know of include serghei a. arutiumov, russia; liu wu, china; inna potieklhim, ukraine; triona g. mcnamara, ireland; yoshitaka manabe, japan; and a number of others who sue met along the way during her ussr odyssey and during her daa editorship. i mention these names here and earlier, probably inappropriately, but to simply illustrate the fine mesh of sue’s professional and social net. a little of each of these friends of sue, and myself, have or will die as a result of sue’s passing. i am at a loss of words to say how much my late wife, jacqueline, and i enjoyed sue and bill’s presence at various gatherings in our home honoring one or another graduate student’s completion of his or her program, and various visits by established scholars. sue and bill almost always sat on the large built-in couch by the big front room window. they were older than most of the other guests, but their quiet cheerful presence always gave class and respect to the evening gathering. christy g. turner ii regents’ professor emeritus arizona state university christy g. turner ii continued 35obituary: alice m. f. haeussler (1932-2009) partial bibliography haeussler amf. 1993. siberian kitoi culture and its place in paleo-indian genealogy. am j phys anthropol suppl. 16:101-102. haeussler amf. 1996. dental anthropology of russia, ukraine, georgia, central asia. evaluation of five hypotheses for paleo-indian origins. ph.d. dissertation, arizona state university. haeussler amf. 1995. dental anthropology of the russian mesolithic era: oleneostrovski mogil’ink. in: radlanski rj, renz h, editors. proceedings of the 10th international symposium on dental morphology. berlin: “m” marketing services, p 314-319. haeussler, am. 1995. upper paleolithic teeth from the kostenki sites on the don river, russia. in: j moggi-cecchi j, editor. aspects of dental biology, paleontontology, anthropology and evolution. florence: international institute for the study of man, p 315-332. daa subscription the secretary-treasurer of the dental anthropology association is dr. loren r. lease of youngstown state university. dr. loren r. lease department of sociology and anthropology youngstown state university one university plaza youngstown, ohio 44555 usa telephone: (330) 941-1686 e-mail: lrlease@ysu.edu dental anthropology now is published electronically and e-mailed to all members as a pdf. the pdf is published with color illustrations, though the printed version is in black-and-white. if you also want to receive a hard copy, be sure to make this clear on the membership form at the daa website or contact loren. speed communication about your membership by contacting loren directly (other officers may not have current membership lists). electronic versions (as pdf files) of all back issues of dental anthropology are available gratis at the association’s web site that is maintained at the ohio state university: the web site’s home page is: http://anthropology.osu.edu/daa/index.htm haeussler am, irish jd, morris dh, turner cg ii. 1989. morphological and metrical comparison of san and central sotho dentitions from southern africa. am j phys anthropol 78:115-122. haeussler, am, and turner cg ii. 1992. the dentition of central asia and the quest for new world origins. lukacs jr, editor. culture, ecology, and dental anthropology. j hum ecol, special issue 2:273-297. irish and kenyhercz 2013.5 38 over 20 years ago, edward harris proposed an approach to compare mesiodistal (md) and buccolingual (bl) crown diameters that employed principal components analysis (pca) (harris, 1997; harris and bailit, 1988; harris and rathbun, 1991). one major goal, like that of other workers (e.g., penrose, 1954), was to remove overall “size” - which is ineffective for biological affinity estimates and phylogenetic analyses. however, relative size is important, i.e., how it is apportioned among crowns along the tooth rows. to get at such data, harris used three size predictors in multiple linear regression to calculate pc 1 residuals; these and the other uncorrected components were then used in analysis. this approach is called tooth size apportionment (tsa) analysis. it was used by several other researchers (e.g., hemphill, 1991; hemphill et al., 1992; irish and hemphill, 2001, 2004) to quantify sample differences ranging from global to local in scale -before its appeal diminished. like clothing, analytical methods go in and out of style. when “sexy” approaches involving lasers, adna, and stable isotopes emerge, the “old ways” are often forgotten. the purpose here is to show that “old” is not the same as “out-dated;” through tsa, useful results can be achieved with easy-toobtain odontometric data – all without destructive sampling and at a fraction of the cost. materials up to 32 md and bl measurements in the left maxillary and mandibular dentitions of 12 (n=712 inds) sub-saharan and 18 (n=1251) north african samples for the present study were recorded. nonmetric findings in these same samples support a known biocultural dichotomy between populations living north and south of the sahara (irish, 1997, 1998a,b, 2005, 2006). the names (incl. abbreviations in figs. 3 and 6), composition, and origins of these 30 samples are presented in the aforementioned publications. their approximate geographic locations are plotted in figure 1. methods following harris’ [and hemphill’s (1991)] approach, sexes-pooled mean measurements were obtained for each sample (sex dimorphism relates to crown size not shape). ordinarily, either these data or their z-scores would be submitted to pca to obtain a rotated (harris) or unrotated size does matter: variation in tooth size apportionment among major regional north and sub-saharan african populations joel d. irish 1 and michael w. kenyhercz 2 1research centre in evolutionary anthropology and palaeoecology, liverpool john moores university 2department of anthropology, university of alaska, fairbanks, ak 99775-7720 keywords: odontometrics, prinicipal components analysis, dental anthropology, africa, biological affinity abstract in the 1980s edward harris proposed an approach using principal components analysis to compare mesiodistal and buccolingual crown diameters in humans. a major goal was to remove overall “size” from the measurements – which is ineffective for biological affinity. relative size, however, is important, i.e., to assess how it is apportioned along the tooth rows. to get at such data, harris utilized three size predictors in multiple linear regression to calculate pc 1 residuals, which were then used with other uncorrected components in analysis. here we demonstrate that it is still an effective method, by comparing 32 md and bl measurements in 12 (n=712) and 18 (n=1251) samples from sub-saharan and north africa. plotting of the first three components (50% of variance) shows clear separation between regions. north africans are characterized by: 1) small li1s, and bl dimensions of the um1, li2, and lm1, and 2) large md diameters of the um2 and lm1, and bl diameters of the lm2 and lm3. comparisons of north africans only show the ability to distinguish among samples from the maghreb, egypt, and nubia. in other words, basic crown diameters can be successfully used for affinity estimation, if relative size, a.k.a., “shape” is accounted for. correspondence to: joel d. irish, research centre in evolutionary anthropology and palaeoecology, school of natural sciences and psychology, liverpool john moores university, byrom street, liverpool l3 3af, united kingdom. j.d.irish@ljmu.ac.uk 39 (hemphill) solution. the pc1 size factor would be addressed through use of residuals as noted above. however, this approach was questioned by jungers et al. (1995), among others, who prefer size correction via darroch and mosimann’s (1985) geometric mean (gm). following their lead, the product of all 32 measurements in this study by sample was calculated, the 32nd root obtained, and the resulting gm used as divisor of each measurement to effect correction. these dm values were then submitted to pca, to yield unrotated pc loadings and factor scores. results and discussion to illustrate the effectiveness of dm size correction, the eight sexes-pooled mean md maxillary measurements for combined samples of north and sub-saharan africans are plotted in figure 2. north africans exhibit smaller dimensions in all cases. compare this line graph to that at the top of figure 5 after size correction. it can be seen that relative between-sample size (a.k.a. shape) varies; that is, it is apportioned differentially along the tooth row: in this example, north africans have relatively larger ui1, up4, um1, and um3 md dimensions. five components with eigenvalues of >2.0 were retained (see table 1); they account for >63% of the total variance. plotting of first three factor scores (<50% of variance) yielded the distribution in figure 3. the north and sub-saharan samples show fig.1. origins of the 30 north (red dots) and subsaharan (blue) samples. fig. 2. md maxillary measurements in pooled north and sub-saharan samples. 40 measure pc1 pc2 pc3 pc4 pc5 dm_mui1 -.098 -.246 .123 .596 .356 dm_mui2 .546 .466 -.026 -.082 .401 dm_muc .151 -.575 .234 -.224 .209 dm_mup3 .429 .343 -.083 .111 .527 dm_mup4 -.294 .138 -.130 .219 .242 dm_mum1 -.419 .252 .028 -.238 .175 dm_mum2 .099 .543 .467 -.113 -.317 dm_mum3 -.377 .371 .246 .393 -.407 dm_bui1 .085 -.698 .057 .053 .110 dm_bui2 .400 -.310 .196 -.512 .471 dm_buc .429 -.654 .115 -.175 .035 dm_bup3 .777 .121 .158 .319 .117 dm_bup4 .456 -.179 .344 .437 -.073 dm_bum1 -.588 -.170 .501 .095 .262 dm_bum2 .287 -.153 .784 -.099 -.328 dm_bum3 .600 .067 .255 .243 -.080 dm_mli1 -.512 -.234 -.023 .635 .064 dm_mli2 -.342 -.265 -.329 .539 -.220 dm_mlc .498 -.078 -.225 -.329 -.511 dm_mlp3 .653 .323 -.352 .144 -.138 dm_mlp4 -.044 .366 -.649 .022 .053 dm_mlm1 -.079 .523 -.329 -.013 .346 dm_mlm2 -.479 .432 .079 -.368 .333 dm_mlm3 -.379 .382 .092 -.162 .319 dm_bli1 -.684 -.489 -.162 -.025 -.212 dm_bli2 -.645 -.499 -.257 -.179 -.219 dm_blc -.030 -.659 -.222 -.603 .025 dm_blp3 .674 .068 -.170 -.003 -.292 dm_blp4 .299 .132 -.644 -.081 -.353 dm_blm1 -.705 .402 .088 -.150 -.125 dm_blm2 -.279 .517 .388 -.282 -.521 dm_blm3 -.094 .628 .203 -.145 -.019 table 1. pca loadings (high-magnitude values in boldface) obvious separation, as previously as identified by dental nonmetric (irish, 1997, 1998a,b, 2005, 2006) and other biocultural findings. the pc loadings in the table provide specifics on tsa. high magnitude negative pc1 loadings characterize north africans on the right of the x-axis in figure 3, i.e., relatively large li1, and bl-only values for um1, li2, and lm1. high positive pc1 loadings for the sub-saharan samples show a relatively large lp3, md-only for ui2, and bl-only for up3 and um3. the tsa differences on pc2 and pc3 similarly account for sample locations on the yand z-axes (figure 3). to utilize information in all five pcs, ward’s cluster analysis was used to classify samples (figure 4) based on the factor scores derived from dm_values (figure 5). three main clusters are evident in figure 4: (1) sub-saharan only, (2) north african only, and (3) north african with four sub-saharan samples. interestingly, the latter samples are from regions 41 fig. 3. samples plot of first three factor scores. fig. 4. ward’s cluster analysis of all five factor scores (showing three main clusters as identified in the text). 42 fig. 5. average md and bl dm-values in upper and lower jaws. 43 fig. 6. samples plot of first three factor scores for north africans only. in the proximity of “northern” peoples (e.g., somalia) -which may reflect evidence of admixture. finally, to demonstrate that tsa analysis can be applied on a regional scale as well, just the 18 north african samples were compared. figure 6 illustrates that, even at this finer-grained level of study, some differentiation among the nubian, egyptian, and maghreb samples is possible. in other words, the results presented here indicate that an “old” method and basic crown diameter data can be successfully used for affinity estimation, if overall size is accounted for and “shape” is considered. thus, (relative) size does matter. acknowledgments we thank heather edgar, helen liversidge, and loren lease for the invitation to the aapa symposium in honor of edward harris. thanks also go to everybody at the institutions from which jdi collected the data. funding was provided to jdi by the national science foundation (bns0104731), wenner-gren foundation (#7557), national geographic society (#8116-06), institute for bioarchaeology, asu research development program, hierakonpolis expedition, and american museum of natural history. literature cited darroch jn, mosimann je. 1985. canonical and principal components of shape. biometrika 72:241-252. harris ef. 1997. a strategy for compareing odon tometrics among groups. dent anthropol 12:16. harris ef, bailit hl. 1988. a principal components analysis of human odontometrics. am j phys anthropol. 75:87-99. harris ef, rathbun ta. 1991. ethnic differences in the apportionment of tooth sizes. in: kelley ma, 44 larsen cs, editors. advances in dental anthropology. new york: wiley-liss, p 121-142. hemphill be. 1991. tooth size apportionment among contemporary indians: an analysis of caste, language, and geography. ph.d. disser tation, university of oregon, eugene. hemphill be, lukacs jr, rami reddy v. 1992. tooth size apportionment among contemporary indians: factors of caste, language, and geogra phy. j hum ecol 2:231-253. irish jd. 1997. characteristic highand low frequency dental traits in sub-saharan african populations. am j phys anthropol 102:455 467. irish jd. 1998a. dental morphological affinities of late pleistocene through recent sub-saharan and north african peoples. bulletins et memoires de la societé d'anthropologie de paris. nouvelle serie 10:237-272. irish jd. 1998b. diachronic and synchronic den tal trait affinities of late and post-pleistocene peoples from north africa. homo 49:138-155. irish jd. 2005. population continuity versus dis continuity revisited: dental affinities among late paleolithic through christian era nubians. am j phys anthropol 128: 520-535. irish jd. 2006. who were the ancient egyp tians? dental affinities among neolithic through post-dynastic samples. am j phys an thropol 129:529-543. irish jd, hemphill b. 2004. an odontometric inves tigation of canary islander origins. dent an thropol 17: 8-17. irish jd, hemphill b. 2001. les canaries ont-elles été colonisées par les berbères d’afrique du nord? la contribution de l’analyse odonto métrique. in: hadjouis d, mafart b editors. la paléo-odontologie: analyses et méthodes d’é tude. collection paléoanthropologie et paléopa thologie osseuse. paris: editions artcom. p 122 -137. jungers wl, falsetti ab, wall ce. 1995. shape, relative size, and size adjustments in morpho metrics. yrbk phys anthropol 38:137-161. penrose ls. 1954. distance, size and shape. ann eugenics 18:337-343. 67 dental anthropology 2019 │ volume 32 │ issue 02 age and sex-related topography of carious lesions and oral conditions among prehispanic coastal mayas andrea cucina 1* , oriana chiappa 1 , thelma sierra sosa 2 1 school of anthropological sciences, universidad autónoma de yucatán (uady), mérida, mexico 2 institute of anthropology and history (inah), yucatán center, mérida, mexico keywords: oral health, caries topography, antemortem tooth loss, maya, prehispanic, mexico studies of carious lesions in prehispanic maya societies from the northern lowlands (i.e. the peninsula of yucatan, mexico) have highlighted a marked heterogeneity in the frequency of such lesions (cucina et al., 2011), regardless of the sites’ geographical location. significant access to non-cariogenic proteins of marine origins (fish and seafood), which characterize coastal sites, is not found to buffer the sites’ settlers from the insurgence of carious lesions (cucina et al., 2003, 2011; seidemann & mckillop, 2008). likewise, dental caries is not always an indicator of poor nutrition affecting mainly the fringes or commoner segments of the society (cucina & tiesler, 2003, 2007). the present study focuses on the maya site of xcambó, which is dated to the classic period (ad 250700) and is located along the northern shores of the yucatan peninsula (mexico) (figure 1). the site was an autonomous port of trade dedicated to the production and administration of marine salt, and its population was characterized by a relatively homogeneous and high socioeconomic level, though no true political elite lived there (sierra sosa et al., 2014). previous papers (cucina et al., 2003, 2011) revealed that the human skeletal collection from xcambó manifested among the highest frequencies of carious lesions in comparison with other inland and coastal sites from the region. cucina et al. (2003, 2011) have already discussed the generic causes of xcambó’ s high frequency of dental caries, with the 2003 paper investigating the oral conditions in the site’s different compounds. given the site’s economic wealth, and the large amount of fish and animal remains recovered, which suggests a diet abstract objectives: the objective is to assess topographic distribution of carious lesions on the crown and cement-enamel junction (cej) by sex and age class and relate it to food intake. materials and methods: sixty-eight males and 45 females aged 15 years and older from the prehispanic classic period maya site of xcambó (ad 250-700) were selected and organized into 15-30 years, 31-45 years and 46+years age classes. caries were scored on all permanent teeth based on their location on the crown, interstitial cej as well as buccal and lingual cej. antemortem tooth loss (amtl) was considered as present when the tooth socket was remodeled and the bone reabsorbed to such an extent that it no longer provided support for the tooth. results: caries affected 14.6% of the permanent teeth in males and 27.7% in females. about half of all the lesions were located at the mesial and distal cej edge of the teeth (50% in males and 46.6% in females), while 12.9% and 17.1% (respectively for males and females) affected the buccal and lingual cej edge. multiple carious lesions were found on 19.7% of teeth in males and 24.9% in females. lastly, amtl was recorded in 16.4% of sockets in males and in 27.4% in females. the overall frequencies of dental caries and amtl increase with age at death, and differences by sex are statistically significant; on the contrary, interstitial cej, buccal and lingual cej and multiple carious lesions do not follow an age-related pattern of distribution, and do not show statistically significant differences between males and females when differences are analyzed using chi-squared test. discussion and conclusions: the coastal site of xcambó shows one of the highest frequencies of dental caries in the region. the high socioeconomic status of the site suggests that carious lesions were not due to a diet based on maize, but that also sugary (honey and various fruits) and starchy foods were ingested on a daily basis. cariogenic sticky foodstuff, which likely triggered dental caries progression at the buccal and lingual cej edges of the teeth, were ingested by all the members of the society regardless of sex and age. *correspondence to: andrea cucina school of anthropological sciences universidad autónoma de yucatán cucina@correo.uady.mx, acucina@yahoo.com mailto:cucina@correo.uady.mx mailto:acucina@yahoo.com 68 dental anthropology 2019 │ volume 32 │ issue 02 with heavy animal protein consumption, the authors pointed to both lifestyle and daily habits, and to the access to cariogenic food like honey, as causative factors for carious lesions. according to their findings, and to the evidence that both males and females equally increased in carious lesion frequencies from an earlier time, access to such “exotic” types of food was granted to both sexes and was not gender related. however, all these studies (see cucina et al., 2011 for a list of comparative studies and related publications) focused on the overall frequency of carious lesions regardless of their topographic location on the crown or around the teeth cervical edges. topographic distribution of carious lesions is meant to be informative of the kind of food ingested, in particular for cervical caries that are considered indicative of a starchy diet and are found to affect mainly older individuals (lanfranco & eggers, 2010; lingström et al., 2000). based on these premises, the present study aims at investigating the topographic distribution of carious lesions by age and sex in the permanent dentitions of a selected sample from the classic period maya skeletal collection of xcambó. the purpose of this study is to assess, and interpret it from a biocultural perspective, whether age and sex play a role in the onset of different kinds of carious lesions (i.e., crown vs cervical), or whether the qualitative (topographic) distribution of carious lesions is independent from the individuals’ biovital parameters. materials and methods the skeletal sample was excavated between 1996 and 2000 by one of the authors (tss, national institute of anthropology and history, yucatan center) (sierra sosa, 1999; sierra sosa et al., 2014). the skeletal collection is currently housed at the bioarchaeology and histomorphology laboratory, school of anthropological sciences, autonomous university of yucatan (uady). for the present study, 113 individuals were selected. in order to avoid interobserver error, only individuals scored by the senior author were chosen. the final sample comprises 68 males and 45 females, and is composed of individuals for whom sex and an age at death of 15 years and older could be estimated. individuals not scored by the senior author, without a clear sex determination, and whose age at death did not fit into the 15-30 years, 31-45 years and 46+ years age categories, were excluded from the present study. every individual was assigned to one of three age categories by sex: 23, 30 and 15 individuals comprise the male sample by age classes, and 9, 12 and 24 individuals the female one. biovital data were extrapolated from the skeletal collections’ database of the bioarchaeology and histomorphology laboratory (uady). a total number of 1,915 permanent teeth and 2,437 sockets were studied. all the available permanent teeth were scored for the presence of carious lesions, while tooth sockets were evaluated for antemortem tooth loss (amtl). it must be stressed that the skeletal collection of xcambó is characterized by a relatively low degree of occlusal wear. therefore, attrition was not a limiting factor for scoring dental caries and its subsequent analysis. carious lesions were scored following a 0-4 scale, with grade zero indicating no lesions; grade 1 indicates that the lesion had affected only the enamel; grade 2 corresponds to the lesion that had penetrated into the dentine. caries were scored as grade 3 when the lesion had penetrated into the pulpal chamber, and grade 4 indicated a cavity that had destroyed more than half of the crown (cucina et al., 2003, 2011). lesions were considered as present when they had penetrated into the dentine; therefore, caries affecting only the enamel were considered as absent (hillson, 2001; cucina et al., 2011). carious lesions were scored according to their location on the crown and long the cej. when carious lesions had affected the exposed root, they were recorded as such, and included with cej or cervical lesions (watt et al., 1997). for the purpose of this study, carious lesions affecting any side of the crown were considered all together; mesial and distal cej carious lesions, instead, were analyzed separately from those of the buccal and lingual cej. multiple carious lesions have been counted regardless of their location on the crown or the cej. the frequencies of teeth presenting mesio-distal cej, bucco-lingual cej, as well as multiple carious lesions were calculated based on the number of carious teeth. in this case, mesio-distal cej and buccolingual cej are not mutually exclusive because some teeth did present both kinds of lesions at the same time. the presence of amtl was considered when the maxillary and mandibular bones were available for figure 1. geographical location of the site of xcambó within the context of the northern maya lowlands, yucatan. 69 dental anthropology 2019 │ volume 32 │ issue 02 study, the tooth socket was remodeled, and the bone had reabsorbed to such an extent that it could not provide support to the tooth. the overall rate of amtl was calculated on the exclusive basis of the total number of sockets available. comparative analyses were run using chi-squared statistical test. sample size was large enough that it did not need yate’s correction or the use of fisher’s exact test. results table 1 lists the frequency of carious lesions for the anterior, posterior, and total dentition by sex and classes of age (see also figure 2 for the graphical distribution by sex and age). carious lesions are more frequent in the posterior dentition in comparison with the anterior teeth. in male individuals, lesions range from 13.2% in the 15-30 years age class, to 20.5% in the 46+ class, with a total value of 14.6%. females, on the other hand, range from 17.3% in the younger class to 37.5% in the older, with a total frequency of 27.7%. differences between sexes are statistically significant (chi-squared=48.17, 1 d.f., p=.000), as previously noted also by cucina et al. (2011) in a late classic-only sample. as expected, frequencies of lesions increase with age for all the categories with the exception of the anterior teeth in the male sample, for which the highest frequency (7.7%) can be found in the younger age class. the topographic distribution of carious lesions, whose frequency has been calculated out of the total number of teeth with carious lesions, is described in table 2 and graphically represented in figures 3 and 4. mesio-distal cavities at the cej (table 2 upper part, and figure 3) tend to increase with age in both sexes, with the exception of the anterior teeth in the male segment of the collection. overall, about half of all the carious lesions scored in the collection are located in between teeth long the cej edge of the crown. differences by sex are not significant (chi-squared=0.4206, 1 d.f., p=.5166). location at the buccolingual edges of the cej (table 2 lower half, and figure 4) is less frequent that at the mesiodistal one. their distribution by sexes and age classes ranges between 0% and 100%; the latter (100.0%) however, is the result of only four carious lesions. overall frequencies total 12.9% in males and 17.1% in females; similar to the mesio-distal cej lefigure 2. frequency of carious lesions by sex and age-at-death for anterior, posterior, and total dentition. anterior posterior total males caries cariesfree % caries cariesfree % caries cariesfree % 15-30 12 144 7.7% 46 239 16.1% 58 383 13.2% 31-45 10 213 4.5% 68 280 19.5% 78 493 13.7% 46+ 4 63 6.0% 38 100 27.5% 42 163 20.5% total 26 420 5.8% 152 619 19.7% 178 1039 14.6% females 15-30 7 67 9.5% 29 105 21.6% 36 172 17.3% 31-45 9 59 13.2% 33 82 28.7% 42 141 22.9% 46+ 42 101 29.4% 73 91 44.5% 115 192 37.5% total 58 227 20.4% 135 278 32.7% 193 505 27.7% table 1. absolute values and percent frequencies of carious lesions in the anterior, posterior and total dentition by sex and age classes 70 dental anthropology 2019 │ volume 32 │ issue 02 sions, difference by sex is not statistically significant (chi-squared=1.2607, 1 d.f., p=.2615). in general, buccolingual cej carious lesions tend to increase with age, with the exception of the female younger age class, which shows higher frequencies in comparison with the two other age classes. table 3 and figure 5 present the absolute values and percent frequencies of multiple caries within the total number of carious lesions, by sex and age classes. similarl to the overall frequency of lesions, also for multiple caries females present higher frequencies (ranging between 24.4% and 25.9%) than their male counterpart (ranging between 19.2% and 19.7%). in this case, however, differences between sexes are not statistically significant (chi-squared=1.4459, 1 d.f., p=.229). multiple lesions do not follow the same patterns by age and location as the overall rate of dental caries. in fact, the age class that appears to be most often affected by more than one lesion in a single tooth is the 3145 years, both for males and females. also, the category of posterior teeth, which is the one that is more often affected by dental caries, does not always present higher frequencies of multiple lesions. to the same extent as the pattern by age class, also in this case the lack of a clear pattern applies for males and females, and the difference between sexes is not significant (chi-squared=1.4459, 1 d.f., p=.229). last, amtl is presented in table 4 and figure 6. similar to dental caries frequency, amtl also increases with age in both sexes, and the difference between males and females is statistically significant (chisquared=42.1579, 1 d.f., p=.000). the most noticeable increase occurs in the female oldest group, which shows a total frequency of 42.1% in comparison with the 16.1% calculated among females 31-45 years of age. an increase in males, instead, is not as noticeable as in their female counterpart. discussion the sample used in this study is slightly different from the ones previously published by cucina and colleagues (2003, 2011), for it includes a younger age cohort of individuals between 15 and 20 years of age (cucina et al., 2003, 2011 started from age 20 and older), and only used sexed individuals whose age could be assigned to one of the three age classes. nonetheless, overall frequencies are very similar between the studies. as expected, the overall frequency of carious anterior posterior total male carious teeth m-d % carious teeth m-d % carious teeth m-d % 15-30 12 8 66.7% 46 16 34.8% 58 24 41.4% 31-45 10 5 50.0% 68 32 47.1% 78 37 47.4% 46+ 4 1 25.0% 38 27 71.1% 42 28 66.7% tot 26 14 53.8% 152 75 49.3% 178 89 50.0% female 15-30 7 2 28.6% 29 7 24.1% 36 9 25.0% 31-45 9 3 33.3% 33 14 42.4% 42 17 40.5% 46+ 42 27 64.3% 73 37 50.7% 115 64 55.7% tot 58 32 55.2% 135 58 43.0% 193 90 46.6% male carious teeth b-l % carious teeth b-l % carious teeth b-l % 15-30 12 0 0.0% 46 3 6.5% 58 3 5.2% 31-45 10 3 30.0% 68 6 8.8% 78 9 11.5% 46+ 4 4 100.0% 38 7 18.4% 42 11 26.2% tot 26 7 26.9% 152 16 10.5% 178 23 12.9% female 15-30 7 1 14.3% 29 7 24.1% 36 8 22.2% 31-45 9 1 11.1% 33 4 12.1% 42 5 11.9% 46+ 42 7 16.7% 73 13 17.8% 115 20 17.4% tot 58 9 15.5% 135 24 17.8% 193 33 17.1% table 2. frequency of caries location at the mesio-distal and bucco-lingual cej edge for anterior, posterior and total number of teeth by sex and age classes 71 dental anthropology 2019 │ volume 32 │ issue 02 figure 3. frequency of mesial and distal cej carious lesions by sex and age-at-death for anterior, posterior and total dentition. figure 4. frequency of buccal and lingual cej carious lesions by sex and age-at-death for anterior, posterior and total dentition. anterior posterior total male carious teeth multiple % carious teeth multiple % carious teeth multiple % 15-30 12 3 25.0% 46 8 17.4% 58 11 19.0% 31-45 10 1 10.0% 68 15 22.1% 78 16 20.5% 46+ 4 1 25.0% 38 7 18.4% 42 8 19.0% total 26 5 19.2% 152 30 19.7% 178 35 19.7% female 15-30 7 0 0.0% 29 4 13.8% 36 4 11.1% 31-45 9 2 22.2% 33 12 36.4% 42 14 33.3% 46+ 42 13 31.0% 73 17 23.3% 115 30 26.1% total 58 15 25.9% 135 33 24.4% 193 48 24.9% anterior posterior total male amtl total % amtl total % amtl total % 15-30 9 208 4.3% 39 336 11.6% 48 544 8.8% 31-45 34 190 17.9% 70 429 16.3% 104 619 16.8% 46+ 34 151 22.5% 66 219 30.1% 100 370 27.0% tot 77 549 14.0% 175 984 17.8% 252 1533 16.4% female 15-30 4 68 5.9% 12 128 9.4% 16 196 8.2% 31-45 12 101 11.9% 29 153 19.0% 41 254 16.1% 46+ 36 123 29.3% 155 331 46.8% 191 454 42.1% tot 52 292 17.8% 196 612 32.0% 248 904 27.4% table 3. frequency of multiple caries in the anterior, posterior and total dentition by sex and age classes table 4. frequency of amtl for anterior, posterior and total number of open and remodeled sockets by sex and age classes 72 dental anthropology 2019 │ volume 32 │ issue 02 lesions, regardless of the location on the crown or cej, increases with age (hillson, 1996). within sexes, the most noticeable and statistically significant increase occurs between the 31-45 and 46+ age classes, both for males and females; such increase, however, is much more extreme in the female group (respectively, chisquared=11.083, 1 d.f., p=.000871 for females , and chisquared=5.379, 1 d.f., p=.020 for males). differences between sexes, instead, reach significant levels in the 31-45 years age class (chi-squared=8.9387, 1 d.f., p=.002792), and highly significant levels in the 46+ years age class (chi-squared=16.6523, 1 d.f., p=.0000450) (the chi-squared difference between males and females in the younger age group is 1.9707, p=.1603). the fact that females manifest higher frequencies than males in each age class is a phenomenon that has been thoroughly discussed in the literature, and that rests on physiological/hormonal differences between sexes as well as differential access to resources and daily habits (see larsen et al., 1991; lukacs, 1996, 2008; lukacs &largaespada, 2006). in a recent study on carious lesions in two modern samples from northern yucatan (vega & cucina, 2014), females manifested statistically significant higher rates of caries already in the 15-19 year age class. similarly cucina and colleagues (2011) stated that differences between sexes were more marked in the younger age groups (starting at age 20 years), though no values of statistical significance were reported. in the present study, instead, differences between the younger age group by sex does not reach the significance thresholds (though females still manifest more carious lesions than males). it is possible that adding to the present study the individuals aged 15 to 20 years, whose amount of carious lesions tend to be lower because of the younger age, might have contributed to more balanced values between sexes dropping the difference below significance. differently from the quantitative amount of dental caries, results indicate no differences between sexes for multiple caries, for interstitial caries at the cej, and for lingual and buccal caries at the cej. moreover, it is important to stress that none of the above variables presents differences between anterior and posterior teeth, clearly indicating the way teeth are affected in terms of topography and multiple carious lesions does not follow the same anterior vs posterior pattern that characterizes the overall frequency of carious lesions. interstitial dental caries at the cej (mesial and distal cej) is commonly generated by plaque that forms in between teeth, and proliferates in the presence of a diet rich in gelatinized maize and starches (lanfranco & eggers, 2010). experimental animal models suggest that sucrose, maltose, fructose, simple starches or starches in combination with sucrose stimulate the production of cervical lesions, smooth surface lesions or both (frostell et al., 1967; lingström et al., 2000). they are also associated with regular consumption of alcohol, low salivary secretion (xerostomy) and high concentration of salivary lactobacilli (badet & thebaud, 2008; beck, 1990; brown et al., 1986). age and mechanical factors like cervical calculus and periodontal bone reabsorption represent additional elements favoring the insurgence of cervical lesions (banting, 2001; otani et al., 2009). liebe-harkort (2012) found exceptionally high rates of dental caries in an iron age population from sweden. lesions were most common in the cervical region, which the author interpreted as probably related to a dietary pattern where starchy and sticky food tended to accumulate around the neck of the teeth. at xcambó, such lesions are very frequent and affect figure 5. frequency of multiple caries by sex and age-atdeath for anterior, posterior and total dentition. figure 6. frequency of antemortem tooth loss (amtl) by sex and age-at-death for anterior, posterior and total dentition. 73 dental anthropology 2019 │ volume 32 │ issue 02 about half of the carious teeth recorded in both sexes, following a pattern that increases with age. on the contrary, these lesions do not differentiate between anterior and posterior dentition, which can be explained with the fact that, by accumulating in between teeth, plaque finds a hospitable environment regardless of the morphology of the crown above the cervical part of the tooth. buccal and lingual caries at the cej edge, and root caries, instead, were detected in 12.9% and 17.1% of the males’ and females’ carious teeth respectively. in males, anterior teeth present higher frequencies than the posterior teeth, while frequency distribution is more evenly balanced in females. as expected, such figures are much lower than mesial and cervical caries at the cej, because the buccal and lingual sides are less suitable for plaque to deposit and can be more easily cleaned by tongue and salivary autolysis. nonetheless, their presence stresses the hypothesis of intake of sticky and cariogenic food. last, multiple carious lesions affect slightly less than one out of five teeth in males (19.2%) and one out of four teeth in females (24.9%), which indicates that, despite the considerable amount of lesions recorded, the majority of teeth were attacked only by one cariogenic event. little information is available in the literature with regard to the pattern and meaning of multiple carious lesions in human populations. watt et al. (1997) only reported an “average number of surfaces affected by caries per carious tooth” (1997: 617), without specifying the frequency of multiple caries, as well as the possible reasons behind such evidence. frequency of carious lesions at xcambó is one of the highest found among the prehispanic skeletal collections from the yucatan peninsula (cucina et al., 2011). only the coastal site of wild cane cay, belize (seidemann & mckillop, 2008) shows higher frequencies than those recorded at xcambó. according to the authors, the heavy reliance of the wild cane cay inhabitants on tree crops like orbignya cohune, acrocomia mexicana and bactris major, which are soft foods that presumably adhere to the teeth, could account for the high caries rate; this would be exacerbated by the low amount of dental wear. the authors, however, do not report the sample composition by age and sex, so it is difficult to make detailed comparisons, even though the impressive 36.2% of teeth affected by carious lesions remains the highest among the prehispanic maya sites reported in the literature (saul & saul, 1997; glassman & garber, 1999; magennis, 1999; whittington, 1999; cucina & tiesler, 2003; cucina et al., 2003, 2011; marquez & hernández, 2007). in the case of xcambó, the high frequency of dental caries encountered in the female subgroup might also be due to the elevated number of women aged 46+ years in the sample; with 24 individuals, it represents more than 50% of the whole female sample (n=45). nonetheless, if the three age classes were represented by the same number of individuals, the overall frequency would drop to about 24.5% (instead of the 27.7%), a figure that still remains one of the highest frequencies in the maya realm. antemortem tooth loss does not seem to account for differences between sexes, since the frequencies of teeth lost in life (16.4% in males and 27.4% in females) match very close the rates of carious lesions. the topographic distribution of carious lesions opens a new window on the biocultural and dietary habits of these people. in particular, it is worthy to note the similarity in distribution of lesion by sex and location (anterior and posterior teeth), and in some cases, also by age. cervical lesions at xcambó are observed in the youngest age cohort analyzed here, and bucco-lingual cej carious lesions are even more frequent in younger females than in older females. cervical caries have been associated with older ages, mainly as the result of periodontal bone reabsorption (faine et al., 1992; lanfranco & eggers, 2010). although age is definitely a conditioning factor, the presence of cervical caries (both m-d and b-l) in the younger age class indicates that it was not a problem limited mostly to older people, but that affected every segment of the society, as also noted by o’sullivan et al. (1993) in prehistoric british children. as mentioned above, cej carious lesions in general and bucco-lingual cej lesions in particular, are associated with the ingestion of cariogenic starchy and, more so, sticky food (frostell et al., 1967; lanfranco & eggers, 2010; lingström et al., 2000). no data on tartar phytoliths, which could help shed light on the kind of plants ingested, exist yet for the skeletal collection of xcambó. however, iconographic, epigraphic and historical information report the extensive use of maizebased atole beverages to which cocoa, honey and different varieties of fruits were added (fernandez souza, 2019). yutal kakaw (fruity cacao), cacao with honey, sweet cacao were often ingested (beliaev et al., 2009). capulin (a cherry-like small fruit) is reported in several classic period maya sites (lentz, 1999). fernandez souza (2019) reports of tamales (see also taube, 1989) dressed with many different ingredients, many of which were sugar-based like fruits and camote (sweet potato), and an extended use of honey to sweeten different recipes and to make a marmalade of sorts. natural plants also exist that might have entered the local peoples’ diet, as for example the batis maritima (saltwort/beachwort) (marcone, 2003), which is typical of marshy coastland in the yucatan peninsula (lonard et al., 2011); its succulent leaves and seeds are nutritious, starchy, and relatively (but not highly) rich in 74 dental anthropology 2019 │ volume 32 │ issue 02 sugars. although the basic nutritional intake consisted of marine and terrestrial animal proteins, as well as maize, beans and squash (fernandez souza, 2019), all the other kinds of foodstuff mentioned above represented important contributions to the daily intake. we must remember, however, that while the whole population commonly ingested fruits, honey and tamales, other ingredients (like cacao) were oftentimes limited to the society’s wealthier class (cucina et al., 2011). in this perspective, the elevated socio-economic status of the population of xcambó (sierra sosa et al., 2014), in particular during the late classic, permitted them to access also this kind of foodstuff. the picture that emerges based on the kind of foodstuff and food recipes is that the bucco-lingual cej lesions might have been triggered also by the ingestion of sugary sticky fruits and not just by starchy ones. sucrose and fructose, in fact, are more cariogenic than starches, because they enhance the streptococci’s acidic (and cariogenic) activity (lingström et al., 2000). nonetheless, dental caries is the result of a very complex interaction of different intrinsic (ph, salivation, dental plaque) and extrinsic (type of food, timing of food consumption and food preparation) parameters, so a simplistic association between starches and caries must be taken with caution (lingström et al., 2000). in particular, timing of food consumption is a parameter that likely played a role in the insurgence of carious lesions in this population. frequent intake of cariogenic food exposes the individuals to a more intense activity by the oral bacteria (larsen et al., 1991; vega & cucina, 2014); the site’s administrative tasks undertaken by the local people, in particular the male segment, likely exposed them to more frequent ingestion of cariogenic alcoholic and non-alcoholic beverages and food, increasing risks of insurgence of carious lesions, as already proposed by cucina et al. (2011). conclusions in conclusion, dental caries rates at the classic period site of xcambó were among the highest in the yucatan peninsula, regardless of the geographical (coastal or inland) location. the frequency increases with age and is more common in females than males. however, a more detailed distribution of lesions on the crown and cervical edges of the teeth shows patterns not always related to age and sex. the presence of lesions long the buccal and lingual cej edges suggests frequent intake of sticky cariogenic food in this population. the way food was prepared, with honey and fruits oftentimes added to different recipes, and the timing of ingestion seemingly exposed this population to increased risks of developing carious lesions already by a young age. a more detailed topographic analysis of carious lesions in other coastal and inland human archaeological settings from the region, each one within its own biocultural context, will allow a clearer picture of the effects of diet and daily habits on the oral conditions of the inhabitants of the peninsula in prehispanic times. acknowledgments the authors are grateful to lilia fernandez souza, from the autonomous university of yucatan, for the interesting discussion on, and for providing the information about food and modes of preparing it in prehispanic times. a special thanks goes to marin pilloud for organizing this special issue of dental anthropology. references badet, c., & thebaud, n.b. 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(2006). explaining sex differences in dental caries prevalence: saliva, hormones, and ‘‘life-history’’ aetiologies. american journal of human biology, 18, 540–555. magennis, a.l. (1999). dietary change at the lowland maya site of kichpanha, belize. in c.d. white (ed.), reconstructing ancient maya diet (pp. 133– 150). salt lake city: the university of utah press. marcone, m.f. (2003). "batis maritima” (saltwort/ beachwort): a nutritious, halophytic, seed bearings, perennial shrub for cultivation and recovery of otherwise unproductive agricultural land affected by salinity. food research international, 36, 123-130. márquez, l., & hernández, p. (2007). alimentación y salud en algunos pobladores de jaina, campeche, durante el clásico. in p. hernández, & l. márquez (ed.), la población prehispánica de jaina, un estudio osteobiográfico de 106 osamentas (pp. 97–138). mexico city: instituto nacional de antropología e historia. o'sullivan, e.a., williams, a.s., wakefield, r.c., cape, j.e., & curzon, m.e.j. (1993). prevalence and site characteristics of dental caries in primary molar teeth from prehistoric times to the 18th century in england. caries research, 27, 147–153. otani, n., hamasaki, t., inho, s., yoshida, a., awano, s., ansai, t., hanada, n., miyazaki, h., & takehara, t. (2009). relationship between root caries and alveolar bone loss in the first wet-rice agriculturalists of the yayoi period in japan. archives of oral biology, 54, 192–200. saul, j., & saul, f. (1997). the preclassic skeletons from cuello. in s.l. whittington, & d. reed (eds.), bones of the maya: studies of ancient skeletons (pp. 28–50). washington, dc: smithsonian institution press. seidemann, r.m, & mckillop, h. (2008). dental indicators of diet and health for the postclassic coastal maya on wild cane cay. ancient mesoamerica, 18, 1 -11. sierra sosa, t. (1999). xcambó. codiciado enclave económico del clásico maya. arqueologia mexicana, 7, 40–47. sierra sosa, t., cucina, a., price, t.d., burton, j., & tiesler, v. (2014). maya coastal production, exchange, and population mobility. a view from the classic period port of xcambó, yucatan, mexico. ancient mesoamerica, 25, 221-238. taube, k. (1989). the corn tamale in classic maya diet, epigraphy, and art. american antiquity, 54, 31-51. vega lizama, e., & cucina, a. 2014. maize dependence or market integration? caries prevalence among indigenous maya communities with maize-based versus globalized economies. american journal of physical anthropology, 153, 190-202. watt, m.e., lunt, d.a., & gilmur, w.h. 1997. caries prevalence in the permanent dentition of a medie76 dental anthropology 2019 │ volume 32 │ issue 02 val population from the south-west of scotland. archives of oral biology, 42(9), 601-620. whittington, s.l. (1999). caries and antemortem tooth loss at copán: implications for commoner diet. in c. white (ed.), reconstructing ancient maya diet (pp. 151–168). salt lake city: the university of utah press. 3 dental anthropology 2021 │ volume 34│ issue 02 patterns of antemortem tooth loss in late prehistoric westcentral tennessee maria ostendorf smith 1* and tracy k. betsinger 2 1 illinois state university 2 state university of new york, oneonta oral pathology has frequently been an effective barometer of community health and an attestable marker of subsistence strategy in archaeological contexts where material culture provides the interpretive context (e.g., betsinger & smith, 2018; larsen, 1983; larsen et al., 1991; lukacs, 1992; russell et al., 2013; turner, 1979; watson, 2008). maize is a cariogenic carbohydrate (e.g., bibby et al., 1951; horton et al., 1985; newbrun, 1979). caries has been a particularly interpretively useful oral pathological condition in north america, enabling the flagging of maize-intensive agriculture (e.g., emerson et al., 2005; larsen, 1981; powell, 1985; watson, 2008). in the absence of adequate oral hygiene, crown or cervical carious lesions progress to penetrate the pulp cavity resulting in dental necrosis and ultimately to exfoliation of the tooth from the alveolar anchor. in more extensive assessments of caries prevalence (i.e., caries correction factor), antemortem tooth loss (amtl) has been included as a proxy for carious teeth (duyar & erdal, 2003; erdal & duyar, 1999; lukacs, 1995; marquezgrant, 2009). although amtl is primarily attributed to the destructive pathogenesis of caries and periodontal disease (baelum et al., 1986; kida et al., 2006; müller & hussein, 2017; niessen & weyant, 1989; ong, 1998; shaffer et al., 2013; van der velden et al., 2015), there are other causes. these include rapid attrition, ablation, acidogenic response, and traumatic injury (costa, 1980; duyar & erdal, 2003; han & nakahashi, 1996; humphrey & bocaege, 2008; lukacs, 2007; nelson et al., 1999; niessen & weyant, 1989; pollard et al., 1997). although traumatic injury may be a contributing factor in a few cases of amtl in the late prehistoric samples from west-central tennessee, the present study observed that attrition and ablation, as elsewhere in the tennessee valley (smith, 1982), are absolutely not evident. as such, oral pathology is the most apparent contributor to amtl. previous assessment of caries prevalence in late prehistoric human osteologiabstract the later prehistoric subsistence-settlement pattern in the kentucky lake reservoir (klr) of northern west-central tennessee is of interest as human occupation inexplicably terminates by ad 1450 as part of a larger regional depopulation. antemortem tooth loss (amtl) collectively and by tooth type was identified in four site samples from the klr. these are a late woodland (ad 600-900) sample (hobbs) and three middle mississippian period (ad 11001400) hierarchically organized and presumptively maize agriculturalist samples (link/slayden, gray farm, thompson village). amtl prevalence in the hobbs sample is consistent with a native crop and seasonal foraging economy. the amtl in the link/slayden sample is more congruent with the pre-maize late woodland sample than the essentially contemporaneous gray farm site sample. thompson village, a later-dated satellite community of the gray farm polity, exhibits significantly fewer amtl than gray farm. this may flag climate-influenced agricultural shortfall of dietary carbohydrates later in the occupation sequence. additionally, males in the gray farm site sample have significantly more amtl than males in the other two mississippian samples. the patterns suggest regional, possibly shortfall mitigated, differences in maize intensification with a polity-specific male-focused maize consumption in the gray site. *correspondence to: maria ostendorf smith department of sociology and anthropology illinois state university email: msmith@ilstu.edu keywords: mississippian, maize, vacant quarter, tennessee 4 dental anthropology 2021 │ volume 34│ issue 02 cal samples from northern west-central tennessee did not identify a clear temporal trend of caries increase with agriculturalization suggesting regional variability in the reliance of maize relative to domesticated native seed crops (smith & betsinger, 2019), a not uncommon phenomenon elsewhere in the mississippian world (e.g., hart & lovis 2013; hutchinson et al., 1998; scarry, 1993). a renewed look at oral health using amtl data and a larger sample of sites may help clarify the lack of comparative oral health congruence with maizeintensive samples. given the inexplicable abandonment of the region by ad 1450 as part of the large scale depopulation of the lower ohio river valley (“the vacant quarter”) (cobb & butler, 2002; williams, 1990), the temporal and regional differences in amtl may also provide some eco-political insight. the maize-intensive subsistence economy in the eastern united states temporally associates with the mississippian period (~ad 1000 – 1500) and life way, the apex of which (ad 1200-1400) is sociopolitically characterized as having centralized (possibly chiefdom level) authority, a complex iconographic-rich cosmology, a well-organized aggregated village settlement pattern, shelltempered pottery, and wall trench architecture (bense, 2016; cobb, 2003; king, 2002; king et al., 2007; lewis et al., 1998; peregrine 2013; wilson, 2017). since the mississippian period material culture correlates are present in the late prehistory of upper west-central tennessee, a maize-intensive agricultural subsistence economy has been proposed (bass, 1985; dye, 2004, 2007; krus & cobb, 2018; lunn, 2013; mainfort, 1996). the purpose of this assessment is to clarify why the mississippian period kentucky lake collective site sample from link [40hs6] and slayden [40hs1] did not exhibit a caries frequency or pattern consistent with unequivocal maize-intensive comparative samples from tennessee (smith & betsinger, 2019). materials and methods archaeological context in eastern north america, the time period spanning the late woodland (~ad 600-900) to the apex of the subsequent mississippian period (~ad12001400) is one of marked regionally and temporally variable economic, settlement, and sociopolitical change (bense, 2016; vanderwarker et al., 2017; fritz, 1990; nassaney, 2001; scarry, 1993; wilson & sullivan, 2017). the subsistence-settlement pattern of the late woodland is generally characterized by dispersed small villages within circumscribed territories that economically engaged in cultivating native seed crops as well as foraging strategies (i.e., the eastern agricultural complex) (bense ,2016; fritz, 1990; nassaney, 2001; scarry, 1993). this pattern is archaeologically evident in central tennessee (shea, 1977). the geographic distribution and the ensuing time period of the mississippian is defined by the transition to maize-reliant agriculture (bense 2016; fritz, 1992; krus & cobb, 2018; lewis et al., 1998; vanderwarker et al., 2017), palisaded aggregated villages with one or more variably functioning (e.g., domiciliary, mortuary, temple) platform mounds flanking a central plaza, and more complex, likely hierarchical, social organization (bense, 2016; king & freer, 1995; schroedl, 1998). in the greater southeast, the mississippian period is also iconographically rich (i.e., “southeastern ceremonial complex” or “southeastern ceremonial exchange network”) (bense, 2016; king et al., 2007). the typical mississippian large aggregated settlement was organized around a central plaza that was flanked by flat-topped mounds which variably served as platforms for domiciles, temples, mortuary structures (e.g., charnel houses, mound burials), or community buildings (bense, 2016; lewis et al., 1998; nash, 1968). mound settlements were civic-ceremonial polity centers geographically surrounded by satellite communities and separated from other mound-centered polities by buffer zones (bense, 2016; dye ,2004; hally, 1993). the sites of gray farm (40sw1), thompson village (40hy5), link farm (40hs6)/slayden (40hs1), and hobbs (40hs44) are located in the lower tennessee river valley of west-central tennessee in the projected catchment area of what is now the kentucky lake reservoir (klr) (figure 1). the sites were excavated between 1938 and 1944 as part of extensive salvage archaeological recovery operations conducted by tva (tennessee valley authority) and the federal wpa (works progress administration) program prior to the completion of the kentucky dam (gilbertsville, kentucky) (dye, 2013). this section of the tennessee river valley lies between the western tennessee uplands on the west, and the steep hills of the western highland rim on the east. the archaeological recovery of the sites’ material culture and skeletal material was hampered by time constraints, many years of agricultural activity, highway construction, and extensive looting (bass, 1985). there are no monographic site reports for any of the five sites, but one or other of them has been the source of descriptive or synthetic archaeological assess5 dental anthropology 2021 │ volume 34│ issue 02 ment (bass, 1985; dye, 2002; lunn, 2013). given the absence of carbon samples, the sites are relatively dated (ceramic sequences, mortuary patterning) (bass, 1985). the five site samples examined here consist of the late woodland period (~ad 500-900) site of hobbs (kuemin drews, 2001) and four primarily middle mississippian period (~ad 1100-1350) sites that segregate into two geographically discrete polities (bass, 1985; dye, 2004). hobbs is a mound mortuary site on the main channel of the tennessee river downstream from the link and slayden sites (figure 1). the early-to-middle mississippian period sites of slayden (~ad 1050-1250) and link farm (~ad 1250-1400) are located on opposite shores of the duck river floodplain, geographically close to the confluence with the tennessee river (see figure 1) (dye, 2002, 2007; kuemin drews, 2000; lunn, 2013). the multiple mound site of link farm is argued to have expanded from the slayden village site with the former becoming the administrative center for the middle mississippian period link farm polity (dye, 2002, 2004; lunn, 2013; nash, 1968). given the paucity of human remains recovered from slayden, the site samples are combined for this study as link/slayden. the gray farm polity is located near the confluence of the big sandy river and the tennessee river (see figure 1). the sites included here are the multiple mound gray farm site (~ ad 1150-1400) (dye, 2004) and the thompson village site which fissioned from the former during the late middle mississippian period (~post ad 1250) and remained occupied through the early late mississippian period (bass, 1985) (~ad1350-1450). all aboriginal occupation of west-central tennessee apparently ended before circa ad 1450 (bass, 1985; smith, 2010) as part of the phenomenon of middle mississippian period regional abandonment in the greater lower ohio river valley (the “vacant quarter”) (cobb & butler, 2002; krus & cobb, 2018; williams, 1983). the specific reasons for the abandonment are unclear, but interpretations include corollaries of climate change (i.e., the “little ice age” [~ ad1400-1700]) (grove, 2012; mann et al., 2009, meeks & anderson, 2013) such as resource depletion, and/or endemic warfare (bass 1985; krus, 2013; worne, 2011). although the kentucky lake mississippian period site samples archaeologically exhibit the hallmarks of mississippian settlement organization and iconography, they are not further sub-divisible into temporally and regionally defined cultural phases. this is partly an artifact of pre-excavation site disturbance which impeded stratigraphic control. geographically they are west of the arguably aboriginal interaction-impeding western highland rim geophysical feature as well as outside of the figure 1. map of the kentucky lake reservoir sites utilized in the study. the western boundary of the mississippian period (ad 1000-1450) middle cumberland culture is indicated by the dashed line. 6 dental anthropology 2021 │ volume 34│ issue 02 mississippian period (~ad 1050-1450) middle cumberland region (mcr) (see figure 1) of the central cumberland river valley and its tributaries (beahm, 2013; dowd, 2008; moore & smith, 2001; smith, 1992). there is also no archaeological evidence that the klr samples had contact with mississippian period sites in the mississippi river drainage of west tennessee (mainfort, 1996; mainfort & moore, 1998). however, some shared cultural elements with the mcr (dowd, 2008; ferguson, 1972; smith, 1992) are evident (e.g., infants interred within house structures and at least some use of limestone slabs to line graves (i.e., stone box burials) (bass, 1985; wamsley, 2018). sample and diagnostic criteria the skeletal age at death and differentiation by sex were previously determined using standard nonmetric osteological protocols (buikstra and ubelaker, 1994) and the information is archived in a computer data base. the individuals regarded as adults in the amtl assessment had least two of the third molars in occlusion in vivo. mandibles and maxillae were the primary source of amtl, but loose teeth were included if antimeres were present or if they were accounted for by alveolar bone (either as sockets or remodeled alveolar processes). individuals assessed consisted of the numbered burials; unaffiliated or extraneous teeth were excluded. adults were segregated into three age-at-death categories: young (~18 years to ~35 years), middle age (~35 years to ~50 years of age), and old age (50+) years of age (table 1). teeth were considered present when observed in situ, as loose teeth, and as un-remodeled alveolar sockets. teeth were considered lost antemortem if the socket was porotic and failed to conform to the sharp alveolar contours of an in situ root, displayed abscessing with no accompanying (loose) tooth, and ultimately, by the remodeling/ resorption of the alveolar corpus. teeth were consolidated by arch and antimere and evaluated for amtl by categories of tooth type. incisors and canines were collapsed into a single category (i/c), as were all premolars (pm). molars were assessed by number (m1, m2, m3) and collectively. preservation ranged from fair to poor for all sites limiting the primary assessment to postmortem presence by tooth type rather than pattern(s) of amtl by individual (see table 1). the gray farm sample is particularly poorly preserved; seventy percent of the interments with dental data are not ascribable to an age-at-death category and 23 individuals (~38 %) are assignable to a sex. table 1. demographic overview of sample preservation and segregation by age-at-death and biological sex. link farm/slayden (total n = 252) young m aged old age males females sex-indet.1 males females sex-indet.1 males females sex-indet.1 1 3 2 4 3 1 0 3 0 gray farm (total n = 612,3) young m aged old age males females sex-indet.1 males females sex-indet.1 males females sex-indet.1 0 1 0 9 2 2 2 2 0 thompson (total n = 1032,4) young m aged old age males females sex-indet.1 males females sex-indet.1 males females sex-indet.1 8 14 1 16 19 3 5 8 0 hobbs (total n = 82) young m aged old age males females sex-indet.1 males females sex-indet.1 males females sex-indet.1 1 0 0 1 3 0 0 1 0 1 sex-indeterminate 2 sample total includes individuals not assignable by either age or sex 3 43/61 not ageable, 7/43 sex assignable but not ageable 4 29/103 not ageable, 20/29 sex assignable but not ageable 7 dental anthropology 2021 │ volume 34│ issue 02 therefore, the primary intersite assessments are based on the presence of teeth (loose and in situ), alveolar evidence (preand postmortem loss), and amtl. analytical methods fisher’s exact test (https://www.graphpad.com) was used to test the prevalence differences for all teeth and by tooth category, and in the same categories when segregated by sex and/or age-atdeath. no tests were undertaken for samples of less than ten. small sample sizes prevented several comparisons. for those tests meeting the minimum sample size, the results are considered tentative. results the late woodland hobbs mortuary sample has the lowest total tooth sample prevalence of amtl (14/153, 9.1%) (table 2), but it is not significantly less (p=0.4479) than the middle mississippian link/slayden sample (46/391, 11.8% ) (table 3). however, the hobbs sample has significantly fewer teeth lost antemortem than the middle mississippian site samples of gray farm (p = 0.0001) and thompson village (p=0.0160). the total tooth sample amtl between the gray farm (32.7 and thompson village (16.7%) site samples is also significantly different (p=0.0001). when amtl is further evaluated by the five tooth type categories, the hobbs and link/slayden samples remain congruent (see table 3). hobbs differs in almost all tooth categories from gray farm and from the thompson site sample in the collective loss of molars. link/slayden lost significantly fewer teeth than gray farm in all tooth categories except the first molar, and in many tooth categories compared to thompson village. thompson, with overall fewer amtl than the gray farm, differs from it in fewer incisiform and premolar tooth loss (see table 3). age-at-death comparisons despite the case deficit in the young age at death (see table 2), it is apparent that overall, the young adult cohorts for all four west-central tennessee sites experience the lowest amtl prevalence in each of the respective site samples. where statistical tests are possible, there is a pattern of no intersite differences except for the greater amtl of all molars in gray farm relative to thompson (see table 2). in the middle age cohort, the vulnerability of complex-crowned teeth to factors contributing to amtl is evident. hobbs and link/ slayden exhibit a significant difference in the loss of m1, the molar longest in occlusion, as well as molars overall and the dentition overall. hobbs, however, has significantly fewer teeth lost in more categories than both gray farm and thompson. the link/slayden site sample, in turn, has lost significantly fewer teeth than gray farm and molars compared to thompson. thompson village, with an overall tooth loss in the middle age category of 25% (n=179/715), is significantly lower than gray farm (89/165, 54%) in the loss of incisiform teeth (see table 1) (7.8% versus 36.5%, 13.8% versus 49%), but congruent in the loss of individual molars. meaning, the samples are evidently significantly different in the absolute number of molars lost, but not different in the proportion by molar type (see tables 2 and 3). few meaningful statistical comparisons were possible for many of the tooth categories in the old age cohort (i.e., samples < 10). all samples yielded few individuals in that age category (see table 1) resulting in little available dental data. intrasite and intersite differences by sex site sample dissimilarities (see tables 2 and 3) may be affected by sex-based differences in vulnerability to oral pathology (e.g., lukacs & largaespada, 2006). the samples were first compared for overall amtl differences by sex (table 4). in the collective adult sample, there are no sex differences in amtl in the hobbs and link/slayden samples. there are multiple categories of sex difference in the gray farm and thompson samples. in the gray farm sample, males exhibit significantly more amtl (p=0.0001) than females (43.5% versus 20.8%) and more amtl in the anterior teeth; in the thompson village sample, females have more amtl than males (~18% versus 12.6%) (p=0.0022). however, more tooth categories in the thompson village sample display the higher female amtl prevalence. very few tooth class categories have a large enough young adult case sample to argue a pattern. however, the gray farm sample has more male amtl for all molars and all dentition overall. since most young adult site samples exhibit very few cases of amtl (see table 2) sex differences may be statistically undetectable. sex differences do emerge in the middle age category (see tables 4 and 5). at the link/slayden site, females lose significantly more molars overall (p=0.0088). specifically, the link/slayden females lost 46% (n=13/28) while males lost 13% (n=4/30). antithetically, there is very little sex difference in amtl in the gray farm sample. it is restricted to the incisiform teeth (i/c) with males losing significantly more (males 50% [n=13/26], females 13.6% [n=3/22]). in the thompson village sample, first 8 dental anthropology 2021 │ volume 34│ issue 02 antemortem tooth loss1 link farm/slayden total males females young m aged old tooth i/c 3/124 2.4 0/17 0.0 3/77 3.9 1/28 3.6 0/37 0.0 2/10 20.0 pm 8/106 7.5 0/17 0.0 8/63 12.7 4/16 25.0 3/36 8.3 0/13 0.0 m1 19/64 29.7 4/19 22.2 5/29 17.2 2/10 20.0 11/22 0.0 3/6 50.0 m2 8/56 14.3 2/18 11.0 4/19 21.0 0/11 0.0 6/20 0.0 0/4 0.0 m3 8/41 19.5 5/17 29.4 2/13 11.1 0/16 0.0 0/26 0.0 0/5 0.0 all m 35/161 21.7 11/54 20.4 11/61 18.0 2/37 5.4 17/58 29.3 3/15 33.0 all dent 46/391 11.8 11/88 12.5 22/201 10.9 6/81 7.4 20/120 6.7 5/38 13.2 gray farm total males females young m aged old i/c 46/140 33.0 29/64 45.3 8/59 13.5 0/23 0.0 19/52 36.5 18/33 54.5 pm 38/124 30.6 15/40 37.5 6/42 14.3 0/15 0.0 22/45 49.0 4/14 28.6 m1 26/61 42.6 11/21 52.4 7/20 35.0 0/8 0.0 16/23 9.5 3/6 50.0 m2 22/59 37.3 9/26 34.6 7/20 35.0 1/7 14.3 16/23 69.5 1/5 20.0 m3 23/50 46.0 10/19 52.6 5/18 27.8 0/6 0.0 16/22 72.7 2/7 28.6 all m 71/170 41.8 30/66 45.5 19/58 32.7 1/21 4.8 48/68 70.6 6/18 33.0 all dent 155/434 35.7 74/170 43.5 33/159 20.8 1/59 1.7 89/165 4.0 28/65 43.0 thompson total males females young m aged old i/c 44/743 6.0 6/300 2.0 24/348 6.9 0/70 0.0 21/266 7.8 5/38 79.0 pm 49/554 8.8 8/228 3.5 26/257 10.1 4/56 7.1 26/189 13.8 10/29 34.5 m1 81/253 32.0 26/106 24.5 42/114 36.8 6/28 21.4 49/97 24.9 0/8 0.0 m2 79/247 32.0 31/102 30.4 37/113 32.7 4/23 17.4 40/85 47.0 3/8 37.5 m3 82/215 38.1 32/83 38.5 37/97 38.1 5/24 20.8 43/78 55.1 1/7 14.3 all m 142/715 33.8 89/291 30.6 116/324 35.8 15/75 20.0 132/260 0.8 4/23 17.4 all dent 235/2012 11.7 103/819 12.6 166/929 17.9 25/201 12.4 179/715 25.0 19/90 21.1 hobbs total males females young m aged old i/c 1/55 1.8 0/23 0.0 1/32 3.1 0/8 0.0 0/21 0.0 1/10 10.0 pm 4/35 11.4 0/6 0.0 4/13 30.1 0/6 0.0 0/15 0.0 4/7 57.1 m1 4/20 20.0 0/2 0.0 4/6 66.0 0/2 0.0 1/13 7.7 3/3 100.0 m2 3/24 12.5 1/5 20.0 2/17 11.8 0/3 0.0 0/10 0.0 3/3 100.0 m3 2/19 10.5 0/1 -- 2/5 40.0 0/2 0.0 0/8 0.0 2/3 67.0 all m 9/63 14.3 1/8 12.5 8/28 28.6 0/7 0.0 0/31 0.0 9/9 100.0 all dent 14/153 9.1 1/37 2.7 13/73 17.8 0/21 0.0 1/67 1.5 13/26 50.0 table 2. raw frequencies of antemortem tooth loss by tooth category segregated by sex and by three skeletal age-atdeath categories. 1 dentition was segregated by sex or age; sex-indeterminate dentition was included in the age-at-death samples. 9 dental anthropology 2021 │ volume 34│ issue 02 molars and molars collectively are more commonly lost by females. females lost ~57% of m1 (n=29/51) compared to 34% (n=18/53) in the males. the disparity drives the significance for all molars (p=0.0272) and collectively for all dentition (males n=67/397 [16.9 %], females n=97/405 [24%]). since the three sites with testable samples may have samples that may have a temporal bias (e.g., link/slayden biased by some temporally later link cases), it is possible that the amtl varies by sex between the sites (table 6). comparing the larger middle age category by sex and by site, females apparently vary very little between samples. thompson females significantly differ from gray farm females for only the premolars (pm) (p = 0.0382, thompson 10.6% [n=12/113], gray farm 31.2% [n=5/16]). there are also no statistical differences when all molars are pooled (p=0.0727) (thompson 53% [n=77/145], gray farm 41% [n=25/61]). the scenario is different for the males. the link/slayden sample, with overall the fewest link/slayden x gray farm link/slayden x thompson gray farm x thompson gray farm x hobbs thompson x hobbs link/slayden x hobbs all i/c 0.0001 0.0093 0.0001 0.0001 0.3572 1.0000 pm 0.0001 0.5190 0.0001 0.0288 0.5440 0.3119 m1 0.1413 0.0592 0.1329 0.1083 0.3236 0.5672 m2 0.0196 0.0234 0.4444 0.0342 0.0611 0.7586 m3 0.0428 0.0908 0.3373 0.0103 0.0222 0.2130 all m 0.0001 0.0005 0.0607 0.0001 0.0001 0.2632 all dent 0.0001 0.0001 0.0001 0.0001 0.0160 0.4479 young i/c 1.0000 0.3519 0.4017 --------- pm 0.3094 0.6704 0.6490 --------- m1 ---1.0000 ------------ m2 ---0.2741 ------------ m3 ---0.0712 ------------ all m 0.6495 0.1040 0.0156 --------- all dent 0.2239 0.1681 0.0044 1.0000 0.1408 0.3410 middle age i/c 0.0001 0.0887 0.0001 0.0008 0.3810 1.0000 pm 0.0001 0.5865 0.0001 0.0004 0.2255 0.5462 m1 0.2307 1.0000 0.1100 0.0004 0.0056 0.0132 m2 0.0148 0.2136 0.0636 0.0003 0.0045 0.0741 m3 0.0001 0.0001 0.1515 -------- all m 0.0001 0.0037 0.0039 0.0001 0.0001 0.0004 all dent 0.0001 0.4091 0.0001 0.0001 0.0001 0.0012 old age i/c 0.0764 0.6251 0.0003 0.0261 1.0000 1.0000 pm 0.0978 0.0182 1.0000 --------- m1 ------------------ m2 ------------------ m3 ------------------ all m 0.0135 0.0002 0.2889 --------- all dent 0.6781 0.0780 0.0045 0.3643 0.5953 0.2073 table 3. pair-wise statistical comparisons of antemortem tooth loss based on the raw data from table1. no tests were undertaken if a sample was less than ten cases. statistical significance (p = ≤ 0.05) is indicated by bold font. 1 fisher’s exact test, p = ≤ 0.05; sample n = ≥10 10 dental anthropology 2021 │ volume 34│ issue 02 teeth lost antemortem (7.7%), has fewer molar tooth loss than thompson (p=0.0426) and exhibits significantly fewer tooth loss in all tooth categories from the gray farm sample (with a total tooth loss of 77.8%). although both gray farm and thompson village were occupied until regional abandonment, the thompson site sample has a temporally later sample bias than gray farm. thompson village males have significantly fewer amtl in all but third molar loss (see table 5). overall tooth loss for thompson males is 16.9%. discussion although etiologically multifactorial, the primary clinical causes of amtl are the progressive pathologies of caries and periodontal disease (e.g., baelum et al., 1986; kida et al., 2006; müller & hussein, 2017; niessen & weyant, 1989; ong, 1998; van der velden et al., 2015). both processes are associated with the consumption of carbohydrates in combination with poor oral hygiene (e.g., baumgartner et al., 2009; chapple et al., 2017; hix & o’leary, 1976). as a proxy for pre-columbian carbohydrate consumption, amtl has the potential to augment archaeological information about diet and subsistence. in the context of the precolumbian skeletal samples from the kentucky lake reservoir of northern west-central tennessee, the insights are more than supplemental as archaeological assessment is limited and will likely con link/slayden thompson gray farm hobbs all adults i/c 1.0000 0.0042 0.0002 1.0000 pm 1.0000 0.0043 0.0225 0.2554 m1 1.0000 0.0579 0.3499 --- m2 0.7057 0.7697 1.0000 1.0000 m3 0.3892 1.0000 0.1837 --- all m 0.3981 0.0827 0.1976 0.6478 all dent 0.6908 0.0022 0.0001 0.0851 young i/c ---0.5762 1.0000 --- pm ---1.0000 0.2308 --- m1 ---1.0000 ------ m2 ---1.0000 ------ m3 ---0.4423 ------ all m 0.2881 1.0000 0.0420 --- all dent 0.5918 0.5810 0.0223 --- middle age i/c 1.0000 0.7854 0.0131 --- pm 0.3416 0.8239 0.5166 --- m1 ---0.0297 1.0000 --- m2 ---0.0656 1.0000 --- m3 1.0000 0.5169 1.0000 --- all m 1.0000 0.0272 1.0000 --- all dent 1.0000 0.0001 0.0646 --- old age i/c ---0.1469 ------ pm ---0.0061 ------ m1 ---0.1939 ------ m2 ---0.2364 ------ m3 ---0.1939 ------ all m 0.1923 0.0021 ------ all dent 0.6882 0.0008 ------ 1 sample n ≥ 10 table 4. comparisons of antemortem tooth loss by sex for each site. no test was undertaken if either the male or female cohort consisted of less than ten cases. statistical significance (p = ≤ 0.05) is indicated by bold font. 11 dental anthropology 2021 │ volume 34│ issue 02 tinue to be so for the foreseeable future. absent from the klr archaeological record are radiocarbon dates, therefore, using attributes of the material culture, the sites have been temporally sequenced relative to each other (bass, 1985; dye 2002, 2003, 2004; lunn, 2013). pairing the occupation sequence with the amtl data in the kentucky lake reservoir yielded several potentially interpretively valuable patterns. unfortunately, poor sample sizes restrict assessments by skeletal age at death. therefore, the interpretations of the rate and pattern of amtl should be considered tentative. temporal pattern hobbs, the earliest site sample evaluated here, dates to the late woodland period (~ad 500-900). overall ,there are fewer teeth lost antemortem by the hobbs mortuary site relative to the middle-tolate middle mississippian period gray farm and thompson village samples. the frequencies are consistent with the reconstruction of late woodland subsistence in the tennessee river valley as pre-maize horticulturalists with (at least) seasonal foraging (e.g., mast, fleshy fruits) (bense, 2016; crites, 1978; emerson et al., 2000; kline et al., 1982; mcmahan, 1983). cultigens utilized were the grasses native to the local environment. these were the oily (e.g., iva [sumpweed], helianthus [sunflower]) and starchy seeds (e.g, chenopodium [goosefoot], phalaris [maygrass], polygonum [knotweed], hordeum [little barley]), the latter of which are cariogenic and capable of initiation and progression of tooth decay (e.g., lingström et al., 2000; pollard, 1995). the amtl results for hobbs parallels the prevalence of caries (smith & betsinger, 2019). that is, there were significantly fewer carious teeth compared to maize-intensive samples. the small hobbs sample size did not permit age -at-death amtl comparisons. indeed, the sample was biased in favor of older individuals which, given the progressive nature of amtl, might bias in favor of congruence with samples archaeologically identified as agriculturalist. however, when segregated by age-at-death in the larger middle age category, hobbs sustains the pattern of significantly fewer amtl for all tooth categories compared to gray farm and for the posterior teeth in thompson. the amtl of link/slayden relative to hobbs archaeologically, the link/slayden polity exhibits the material culture attributes of the mississippian period (bass, 1985; dye, 2002, 2003, 2013; lunn, 2013). the link site (ad 1250-1400) is a civicceremonial mound center complex with a central plaza (bass, 1985; dye, 2007, 2012; nash, 1968). although bass (1985) characterized slayden as an expansion site from link, recent ceramic analysis link/slayden gray farm thompson ma males i/c 0/12 0.0% 13/26 50.0% 6/146 4.6% pm 0/10 0.0% 10/23 43.5% 10/108 9.3% m1 3/10 30.0% 9/12 75.0% 18/53 34.0% m2 1/10 10.0% 8/12 67.0% 15/50 30.0% m3 0/10 0.0% 9/12 75.0% 18/40 45.0% all m 4/30 13.3% 26/36 72.2% 51/143 35.7% all dent 4/52 7.7% 49/63 77.8% 67/397 16.9% ma females i/c 0/25 0.0% 3/22 13.6% 8/147 54.4% pm 3/16 18.8% 5/16 31.3% 12/113 10.6% m1 8/12 67.0% 6/8 75.0% 29/51 56.9% m2 5/10 50.0% 6/8 75.0% 24/49 49.9% m3 0/6 0.0% 5/7 71.4% 24/45 53.3% all m 13/28 46.4% 17/23 73.9% 77/145 53.1% all dent 16/68 23.5% 25/61 41.0% 97/405 24.0% 1 statistical tests not undertaken if sample size ≤ 10 table 5. the middle age category generated the largest samples of antemortem tooth loss segregable by sex. however, several tooth classes generated samples of less than ten teeth. these were not eligible for statistical comparisons. table 6. for samples of at least ten individuals, statistical comparisons were undertaken between the site samples by sex. statistical significance (p = ≤ 0.05) is indicated by bold font. link/slayden v thompson link slayden v gray farm thompson v gray farm males i/c 1.0000 0.0026 0.0001 pm 1.0000 0.0303 0.0003 m1 1.0000 0.0237 0.0287 m2 0.2629 0.0115 0.0422 m3 0.0085 0.0016 0.2021 all m 0.0426 0.0001 0.0001 all dent 0.1473 0.0001 0.0001 females i/c 0.6048 0.0950 0.1577 pm 0.3986 0.6851 0.0382 m1 0.7462 ------ m2 1.0000 ------ m3 --------- all m 0.5421 0.0858 0.0727 all dent 0.3063 0.3272 0.0601 1 tests undertaken on samples ≥ 10 12 dental anthropology 2021 │ volume 34│ issue 02 suggests it is the earlier (circa ad 1050-1250) of the two (dye, 2004; lunn, 2013). the link site was arguably abruptly abandoned circa ad 1400, based on the archaeological context of the duck river cache (dye, 2007, 2012; nash, 1968), a large assemblage of ritual performance objects (e.g., crownform clubs, monolithic axes, raptor talon claw effigies) recovered from the site. the cache was arguably deliberately buried as a last act prior to (possibly warfare-related) site abandonment (dye, 2007; dye & king, 2007). although there is a general congruence of amtl between the link/ slayden sample and the late woodland hobbs sample (see table 2), when the samples are segregated by age at death, the mississippian link/ slayden sample does exhibit more molar loss, particularly m1, the molar longest in occlusion. the m1 sample size drives the difference in all molars and all the dentition. previous assessment of the caries pattern and prevalence in the hobbs sample indicated an overall higher prevalence of carious teeth compared to the link/slayden sample (although few tooth classes are significantly higher) (smith & betsinger, 2019). considering the temporal and archaeological context of link/slayden, maize was unequivocally available as a productive cultigen. it is possible that as a shortfall-hedging strategy, food production within the link polity included seasonal foraging and/or cultivation of native cultigens (e.g., gremillion et al., 2008). it is also possible that the wpa era (works progress administration, 1939-1943) (dye, 2017) salvage recovery protocols at link/slayden biased in the direction of a temporally earlier (i.e., incipient/early maize adoption) mortuary sample. more speculative, but an aspect to consider given the archaeologically-based conclusion by bass (1985) that the link polity is ethnically different from gray farm, is regional variability in the symbolic or ritual role of maize or, in the routine maize processing and/or preparation (e.g., roasted, hominy, hoecake, and/or corn mush) which may have reduced the oral bioavailability of starch (e.g., blitz, 1993; briggs, 2016; fritz & lopincot, 2007; katz et al., 1974; peres, 2017; raviele, 2011). the amtl differences between the mississippian samples in the large middle age cohort, the link/slayden site sample has significantly fewer amtl than gray farm in all tooth categories except the first molars. this is unexpected given the apparently extensive temporal overlap of the sites, but may be explained by the scenarios presented above. the gray farm (ad 1150-1400) site sample might be considered exemplary of maize-intensive mississippian agriculturalization. based on the prevalence of carious teeth by tooth type and age-atdeath, the gray farm dental sample certainly allies with definitively maize-intensive late mississippian period sites from (at least) east tennessee whereas link/slayden does not (smith & betsinger, 2019). however, in the middle age cohort, compared to the maize-intensive samples, the gray farm dental sample exhibits small lesion size and virtually no cases of pulp exposure. if the progression of tooth decay was comparatively rapid in the gray farm sample, the carious lesions achieving pulp penetration may have precipitated the earlier exfoliation of affected teeth, generating the high amtl results seen here. the co-occurrence of larger lesions with fewer teeth lost antemortem can potentially be tested in the late mississippian period sites from east tennessee. this faster rate could also explain the significant increase in the frequency of amtl in the anterior teeth (i/c, pm) of gray farm relative to both link/slayden and thompson village (see table 2). caries and amtl initially progress in the complex-crowned teeth with greater interstitial surface area (e.g., broadbent et al., 2006; carlos & gittelsohn, 1965). the greater involvement of the anterior teeth in gray farm may signal an oral environment of advanced tooth decay (e.g., o’sullivan & tinanoff, 1993). possible mitigating factors, as yet unknown, are dental issues such as leh which might predispose the incisiform teeth to pulp-penetrating demineralization. it can be assumed that maize was the primary cariogenic carbohydrate consumed by the community residing in the gray farm site. but evidently, the consumption was differential by, at least, sex (see table 5), but not by the same sex. in the middle age category, gray farm males exhibit more amtl than females (77.8 percent versus 41.0 percent) while the females of link/slayden have the higher frequency (23.5 percent versus 7.7 percent). pregnant and nursing females are arguably more vulnerable to tooth decay and in archaeological contexts may signal reproductive stress (ferraro and vieira, 2010; lukacs, 2011; lukacs and largaespada, 2006; walter et al., 2016), but the statistically significant higher amtl among females in the link/slayden sample (p=0.0260) may also suggest differential consumption of decay-causing carbohydrates (e.g., larsen, 1983; somerville et al., 2015). greater maize consumption by females has been documented elsewhere in the mississippian 13 dental anthropology 2021 │ volume 34│ issue 02 world (ambrose et al., 2003; larsen, 1983). the higher rate of amtl in the males of gray farm strongly suggests greater consumption. this is underscored by the between sample comparison by sex in the larger middle age category (see tables 4 and 5). there are few differences in the prevalence of amtl among the females for all tooth types and all teeth between link/slayden, gray farm, and thompson village. however, male amtl is significantly higher in gray farm than either link/slayden or thompson village in the vast majority of statistical comparisons. the reason for this pattern might include the use of maize in malepredominated ritual feasting. given the similarity of female amtl across the site samples, it does not suggest a simple community pattern of differential maize dietary consumption. as stated earlier, bass (1985) has argued that the link and gray farm polities are ethnically different. this is based on the differences in mortuary protocols in addition to the considerable geographic distance between the two polities. this is certainly plausible given the large buffer zone between the polities in addition to an intervening polity with its own large mound center (dye, 2004). however, the high frequency and male bias of amtl is not repeated in the thompson village sample, a satellite community within the gray farm polity. based on the ceramic sequence and temporal pattern of domestic structure construction, the gray farm site was occupied earlier than the thompson site with the founding of the williams site (40hy1) (no amtl data), part of the gray farm polity, straddling the two (bass, 1985). gray farm, therefore, would have had a mortuary component earlier in time than thompson village. both the gray farm and thompson village sites generated late mississippian period (post ad 1300) ceramic types which suggests both sites, as well as link, were occupied until regional abandonment (“vacant quarter”) of the 14th and 15th centuries (cobb & butler, 2002). if maize adoption intensified with mississippianization, as conventional wisdom suggests (bense, 2016; emerson et al., 2020), the thompson amtl frequencies for all tooth types should be greater than gray farm, even if not significantly so (see tables 1 and 2). they are not. the results may be a by-product of sampling error (biased site recovery, differential preservation, and/or small sample sizes) or reflect local socioeconomic issues. thompson village was a satellite community within the gray farm polity and may not have engaged in, or had access to, the same civic-ceremonial activities of a mound center. that is, if indeed the male amtl bias at gray farm is reflective of non-dietary maize consumption. but the circumstance preceding regional abandonment may have also been a factor in the apparent better oral health of the temporally later thompson village sample. climate volatility maize cultivation may have been affected by a series of droughts that occurred in the southeast beginning circa ad 1100 (aharon et al., 2012; benson et al., 2009) and in tennessee in the middle cumberland river culture area (figure 1) circa ad 1288 -1388 (meeks & anderson, 2013). agricultural shortfall may have episodically reduced overall carbohydrate consumption potentially causing nutritional stress or dietary shifts to foraged resources (e.g., scopa kelso, 2018). this may have been reflective of, or exacerbated by, the onset after ad 1300 of the climate phenomenon of the little ice age (bird et al., 2017; naftz et al., 1996; stahle & cleaveland, 1994; wilson, 2017). nutritional stress may not be documentable,1 but dietary shifts are certainly a plausible scenario based on (for example) the botanical evidence from the illinois river valley of the apparent juxtaposition of maize adoption and reduction in arboreal seed crop harvest (vanderwarker et al., 2017). mast and fleshy fruits may have been fall-back options in times of carbohydrate harvest insufficiency. this may be what was occurring in the link polity and in the later occupation within the gray farm polity. political instability perhaps synergistically related to climate change, there is a wide-spread decline of polities in the late mississippian period (after ~ ad 1300) (anderson, 1994, 1996; benson, et al., 2009; bird et al., 2017; wilson, 2017). although particular mound centers as loci of civic and ceremonial functions did fluctuate over time and space (e.g., anderson, 1996; beck, 2003; benson et al., 2009; blitz, 1999; wilson, 2017), in the middle cumberland river valley to the east of the klr samples, political destabilization occurs circa ad 1325 (dye, 2004; krus & cobb, 2015; vidoli, 2012) just prior to the regional abandonment. this is archaeologically manifested by the reduction in centralized authority and increase in settlement fortification (palisades) (krus & cobb, 2015). warfare is argued to escalate during this time period and, in the klr, the apparent abrupt abandonment of the link site (i.e., burial of the duck river cache) has been attributed to imminent intergroup violence (dye, 2004; dye & 14 dental anthropology 2021 │ volume 34│ issue 02 king, 2007). bass argued that it is only in the later occupation sequence of the mississippian sites that palisades are firmly documented (1985:216). corroboratively, based on a shift in mortuary patterning, bass argues the changes “indicate that the sociopolitical structure of these polities in the late middle mississippian period… had altered to ones in which elite status or high rank was truncated and invested in and restricted to only one rank, an individual kin group or family which produced the chiefly line (1985:195).” perhaps the absence of male-focused decay-inducing carbohydrate consumption in the thompson village sample compared to gray farm is reflective of this political decline with an overall reduction in amtl in thompson is suggestive of agricultural shortfall. conclusions the trend towards maize intensification cooccurring with sociopolitical complexity is a general pattern within the mississippian period (ad 1000-1550) in what is now the lower midwest and much of the southeastern united states. however, the transition varies temporally and unevenly between sociopolitical and/or ecological contexts. mississippianization abruptly ended in northern west-central tennessee by ad 1450. occupation of the area was abandoned as part of a much broader inexplicable depopulation of the lower ohio river valley inclusive of the lower tennessee river valley. the dearth of archaeological context for the kentucky lake reservoir region of northern westcentral tennessee contributes to the conundrum of the apparent abandonment. much basic subsistence information is archaeologically unclear but can be remediated by certain lines of bioarchaeological inquiry. although amtl has a complex etiology, it has been an effective proxy for oral decay which has been bioarchaeologically observed to vary by subsistence strategy and the dietary dependence on starchy cultigens. the amtl observed in the kentucky lake reservoir yielded three patterns which segregate the site samples of hobbs, link/slayden, gray farm and thompson village by temporal period and geographic distribution. the first pattern is the retention of a general late woodland (ad 600-900) amtl loss (hobbs site sample) in the mississippian period link polity (link/slayden site sample). the pattern does not indicate a maizeintensive subsistence strategy. it may reflect a strategically mitigated economic adjustment to include foraged resources consequential to demonstrable climate volatility (~ad 1400-1700). this subsistence strategy is similar to what has been archaeologically reconstructed for the pre-maize late woodland period. however, this pattern may also reflect possible salvage archaeology recovery bias inadvertently favoring temporally earlier link/ slayden burials, which may indeed have practiced a late woodland subsistence economy. less likely, but culturally plausible given that bass argued ethnic differences between the link and gray farm polities, there may have been polity-variable food preparation techniques which reduce the opportunities for dental decay in the oral environment. the second pattern is a regional difference in mississippian period maize adoption. the caries data as well as amtl of the gray farm site sample is consistent with maize-intensive agriculturalization and in contrast with the lower prevalence results of the link polity. indeed, amtl is higher than the thompson village site sample, a temporally later-founded satellite community of the gray farm polity. it is possible that gray farm reflects a temporal window of successful maize overcrop which then declined just prior to regional abandonment. alternatively, maize may have been siphoned from satellite communities to the gray farm site as it was the administrative capitol for the polity. the third pattern is the higher overall prevalence of amtl in the males of the gray farm sample. this contrasts with the link/slayden and thompson village samples which indicated more amtl among the females. interpretively important, the prevalence of amtl is not significantly different between the females in the three mississippian period site samples. therefore, the gray farm male pattern may reflect specific malefocused civic-ceremonial roles which involved maize consumption that may have declined in the later thompson village context paralleling documented sociopolitical decline. alternatively, the civic-ceremonial activity may not have been undertaken in satellite communities. the patterns apparent in this study may be a consequence of sampling error from possible excavation bias as well as small sample sizes available for assessment. however, the patterns may indeed reflect the political landscape as well as the climate, ecological, and sociopolitical challenges of the thirteenth century prior to regional abandonment. hopefully, more health status data can be marshaled to clarify the regional and temporal patterns. 1access to the osteological collections has now been terminated pending reburial 15 dental anthropology 2021 │ volume 34│ issue 02 acknowledgements the authors greatly appreciate the permissions to access and assess the collections curated by the frank h. mcclung museum, knoxville, tennessee. we thank the staff for their forbearance to our presence, particularly dr. jefferson chapman (executive director, retired), dr. lynne p. sullivan (curator of archeology, retired), and dr. timothy baumann (curator of archaeology). we also appreciate and commend the collecting assistance of ms. germaine mosher and ms. amanda bailey. references aharon, p., aldridge, d., & hellstrom, j. (2012). rainfall variability and the rise and collapse of the mississippian chiefdoms: evidence from a desoto caverns stalagmite. in l. giosan, d.q. fuller, k. nicoll, r.k. flad, & pd clift (eds.), climates, landscapes, and civilizations. geophysical monograph series 198 (pp. 35-142). new york: wiley. ambrose, s. h., buikstra, j.e., & krueger, h.w. (2003). status and gender differences in diet at mound 72, cahokia, revealed by isotopic analysis of bone. journal of anthropological archaeology, 22(3), 217-226. anderson, d. g. (1996). chiefly cycling and largescale abandonments as viewed from the savannah river basin. in j. f. scarry (ed.), political structure and change in the prehistoric southeastern united states (pp. 150-191). gainesville: university press of florida. baelum, v. & fejerskov, o. (1986). tooth loss as related to dental caries and periodontal breakdown in adult tanzanians. community dentistry and oral epidemiology, 14(6), 353-357. bardolph, d.n. 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(1993) big pots for big shots: feasting and storage in a mississippian community. american antiquity, 58(1), 80–96. blitz, j.h. (1999). mississippian chiefdoms and the fission-fusion process. american antiquity, 64(4), 577-592. briggs, r.v. (2016) the civil cooking pot: hominy and the mississippian standard jar in the black warrior valley, alabama. american antiquity, 81 (2), 316-332. 1 broadbent, j.m., thomson, w.m., & poulton, r. (2006). progression of dental caries and tooth loss between the third and fourth decades of life: a birth cohort study. caries research, 40(6), 459-465. buikstra, j.e., & ubelaker, d.h. (1994). standards for data collection from human skeletal remains. arkansas archaeological survey research series. carlos, j. p., & gittelsohn, a. m. 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(2017). mississippian origins: from emergence to beginnings. in g.d. 20 dental anthropology 2021 │ volume 34│ issue 02 wilson (ed.) mississippian beginnings (pp. 1-28). gainesville: university press of florida. wilson, j.j. (2017, april). the development of the mid-continental u.s. vacant quarter: the impact of aggression, warfare, and climate change on late pre-columbian population dynamics. paper presented at the annual meetings of the american association of physical anthropologists, new orleans, la. worne, h. (2011). conflicting spaces: biological and geophysical perspectives on warfare in the middle cumberland region of tennessee (unpublished doctoral dissertation). binghamton university, new york. 3 dental anthropology 2020 │ volume 33 │ issue 01 childhood variation in skeletal and dental development anna l.m. rautman 1,2* and heather j.h. edgar 1,2 1 department of anthropology, university of new mexico 2 office of the medical investigator, university of new mexico school of medicine, albuquerque, new mexico the skeletal and dental systems have long been subjects of study in humans. existing studies of the two systems focus either on the sample mean expression or on the correlation between the two systems across the entire sample. this paper examines whether the variation between the systems’ developmental trajectories varies between individuals who were delayed, average, or advanced in their development at an early age. individuals within the average subgroup are included as a baseline with which to compare how the developmental trajectories of delayed and advanced individuals differ. the general order and timing of how a juvenile develops into an adult is consistent among individuals. here, development is used to refer to the change and refinement in shape of objects from their juvenile form to their completed adult appearance (greulich & pyle, 1959; moorrees, fanning, & hunt, 1963). this is to differentiate development from growth, which refers to changes in size (ogden et al., 2002; who multicenter growth reference study group, 2006). the overall order of development, the order at which different bones and epiphyses form and fuse or teeth mineralize, is canalized. canalization refers to the fact that developmental reactions “adjust so as to bring about one definite end-result regardless of minor variations in conditions during the course of the reaction” (waddington, 1942:563). the canalization of the skeletal and dental systems has long lent these systems to being used to estimate chronological age (greulich & pyle, 1959; moorrees, fanning, & hunt, 1963; tanner, 1978). as the development of the skeletal and dental systems roughly correspond to chronological age, it follows that the two systems should be correlated. the correlation is not perfect due to variation between, and even within, individuals. variation within and between individuals is inherent to canalization (flatt, 2005; waddington, 1942). a plethoabstract the existing research comparing variation in developmental timing of skeletal and dental systems has focused on cross-sectional correlations of group means throughout late childhood. we used a longitudinal sample of 100 white american girls to compare developmental variation from 3-12 years to improve our understanding of developmental variation. the sample was divided into two sets (dental and skeletal) of three subgroups (delayed, average, or advanced) based on development at age three. repeated measure anova and tukey’s hsd analyses examined the longitudinal maturation of: 1) skeletal development of skeletal subgroups, 2) dental development of skeletal subgroups, 3) dental development of dental subgroups, and 4) skeletal development of dental subgroups. the four models demonstrated significant differences between subgroup developmental trajectories. pairwise comparisons of same-system development (analyses 1 and 3) found all comparisons to be significant; this was not the case for pairwise comparisons across systems (analyses 2 and 4). only the advanced group was consistently different across all combinations. results suggest that the pace of development differs among delayed, average, and advanced individuals, and between dental and skeletal systems. therefore, to fully explore the relationship between the systems, the full range of variation in the timing of development is required. *correspondence to: anna l.m. rautmann department of anthropology university of new mexico albuquerque, new mexico arautman@unm.edu this paper was the recipient of the albert a. dahlberg prize awarded by the dental anthropology association in 2019. keywords: dental development, skeletal development, inter-individual variation 4 dental anthropology 2020 │ volume 33 │ issue 01 ra of environmental, genetic, and epigenetic factors contributes to the range of variation. regardless of the cause or influence, the entire range of skeletal and dental developmental variation between people is the inter-individual variation in developmental timing (ivdt). the environment can influence ivdt either as developmental stressors (nutritional or pathological) or via developmental plasticity. developmental plasticity is the phenotypic response to the environment given an individual’s genetic and epigenetic profile (hochberg et al., 2011; houston & mcnamara, 1992; kuzawa, 2012; wang et al., 2014). genetic variation and developmental plastic variation are susceptible to evolutionary forces, referred to at the inter-species level as heterochrony (bogin, 1997; love, 2014). an example of genetic and epigenetic differences in ivdt include the known difference between the sexes (badyaev, 2002; ogden et al., 2002); males are known to develop more slowly on average than females (badyaev, 2002; greulich & pyle, 1959). differences in ancestry also must be considered when using developmental timing standards, as a method developed for one population may not be accurate for another population. this can result in either under or overestimation of an individual’s developmental age (haiter-neto, kurita, menezes, & casanova, 2006; zhang, sayre, vachon, liu, & huang, 2009). additionally, differences in population histories (e.g. famine or slavery) can delay or slow the development of disadvantaged groups (jasienska, 2013; ribot & roberts, 1996). non-evolutionary related variation over time also can occur. this is secular change, which is often associated with variation in environments such as improved nutrition and increased caloric intake (garn, 1987). while the effects of secular change on the skeletal system and on total body size have been known for well over a century (boas, 1912), the possibility of secular change affecting the dental system is a more recent field of study (cardoso, heuze, & julio, 2010; nadler, 1998; rautman & edgar, 2013). regardless of the many causes, origins, and types, the entire range of variation is included in ivdt. when the two systems are compared to each other, rather than to chronological age, a common finding is that the skeletal system is more susceptible to environmental and developmental stressors than is the dental (cardoso, 2007b, 2007a; demirjian, buschang, tanguay, & kingnorth patterson, 1985; flores-mir, mauicio, orellena, & major, 2005; lewis & garn, 1960). large discrepancies between chronological age and either skeletal or dental age may be an indicator of an underlying disease or condition or of some other developmental stressor. numerous studies of the skeletal and dental systems have considered the systems individually and together (cardoso, 2007b; hunt & gleiser, 1955; lauterstein, 1961; lewis & garn, 1960). existing studies comparing the development primarily focus on mean/median/modal developmental phenotype, or else the correlation across the entire sample. the mean (most commonly reported) phenotype is crucial to understanding the development of that phenotype. however, the mean expression is not informative about the range of possible variation. such studies assume that the approach to development is the same across the range of ivdt, and that the mean expression is sufficient. by reporting or considering standard deviation in addition to the mean, more focus is placed on the range of variation (al-juboori, saloom, & al-bustani, 2012; bagherpour, pousti, & adelianfar, 2014; gupta, divyashree, abhilash, bijle, & murali, 2013; sachan, sharma, & tandon, 2011). similarly, studies which utilize correlations do consider the entire range of variation (anderson, thompson, & popovich, 1975; arora, 2009; bagherpour et al., 2014; lauterstein, 1961; saglam & gazilerli, 2002). such studies assume that the skeletal and dental correlation is the same across the entire range of ivdt. they ignore the possibility that the relationship between the systems may vary through the ivdt range. the current research considers whether the relative relationship between the skeletal and dental systems is the same throughout the range of ivdt by comparing the correlation of skeletal and dental development between subgroups whose skeletal or dental development was delayed, average, or advanced early in life. subgroups are here defined independently by either the completed skeletal or dental development at age three. the entire sample was divided into subgroups each with 20% of the total ivdt. of the resulting five quantiles per system (five skeletal and five dental), only three per system were considered in the subsequent analysis. these three were those 20% who were delayed; those who were average, the middle 20%; and those 20% who were advanced, all at age three. the delayed, average, and advanced skeletal quantiles were based on percentage of completed skeletal development at age three; while the delayed, average, and advanced dental quantiles were based on percentage of completed dental development at age three. the subsequent skeletal and 5 dental anthropology 2020 │ volume 33 │ issue 01 dental development of each quantile were compared. the null hypothesis was that the relationship would be the same between the three skeletal quantiles and between the three dental quantiles. however, we predicted that the developmental trajectories would vary between those who were delayed, average, or advanced at age three. if the developmental trajectories were to vary between the three quantiles per system’s ivdt, this would indicate that the relationship between the skeletal and dental systems is more complicated than is understood from the general assumption based on a consideration only of means or total sample correlations. this analysis of ivdt does not address the cause of the observed variation, nor should the findings be interpreted as being the result of a specific cause of variation. materials and methods the sample consists of 100 healthy females from the bolton-brush growth study, who were described by the study designers as white, of seemingly normal development, and who were without known major pathological conditions. only one sex was considered for this study to avoid potential complication based on known sex differences in rates of development (greulich & pyle, 1959; stinson, 1985). in order to remove sex as a confounding variable females were chosen as they develop more quickly than males (greulich & pyle, 1959; humphrey, 1998). the bolton-brush growth study is a combination of two related studies, the brush inquiry and broadbent-bolton study, both of which began in the late 1920s in cleveland, ohio. the brush inquiry began in 1926 (nelson, hans, broadbent jr., & dean, 2000) (or 1928 (behrents, 1984)) in order to study how healthy, normal children grew and developed (nelson et al., 2000). included among the data from this study are radiographs of the postcranial skeleton, information on the mental and physical health and growth of the child, and information about the child’s family and home environment (nelson et al., 2000). in 1929, the broadbentbolton study began with the initial purpose of understanding the dentofacial growth and development of normal, healthy children (hans, broadbent jr., & nelson, 1994). this study included radiographs of the head and the hand-wrist, dental casts, and information on the health and developmental environment of each child. although the two studies were independent, many participants were included in both studies. of those individuals in the brush inquiry, 73% also participated in the broadbent-bolton study, while 67% of those in the broadbent-bolton study were also in the brush inquiry (hans et al., 1994; nelson et al., 2000). not all participants joined the studies at the same age. however, participants were seen every three months when less than one-year-old, every six months from one to five years old, and once a year after age five. the selection criteria for the present study were that each girl must have been seen within three months of her third, sixth, ninth, and 12th birthday. in cases in which pairs of sisters were seen at all four ages, only one sister was included. birth dates ranged from january 1928 to may 1934 and were distributed as evenly as possible during this window. for each visit, the lateral cranial and handwrist radiographs were used to measure skeletal and dental development. skeletal and dental development the level of skeletal development was determined by visual observation of left hand-wrist radiographs. the stage of development of 15 bones at 11 sites was determined using greulich and pyle’s atlas of hand and wrist development (greulich & pyle, 1959) to quantify the development of carpals, metacarpals, the radius, and ulna (table 1). when a bone (e.g. trapezium) or epiphysis (e.g. first metacarpal) had not yet begun ossification, it was scored “1” (greulich & pyle, 1959). when assignment to greulich and pyle’s stage 1 stated that ossification had already begun (e.g. scaphoid: “stage 1: ossification usually begins from a single center, pg. 201), radiographs that showed no sign of ossification were scored as zero. radiographs that were too blurry or out of focus to determine the develdevelopment site range of stages number of stages proximal 1st phalanx 1 to 10 10 distal 2nd – 4th metacarpals 1 to 9 9 distal 5th metacarpal 1 to 9 9 trapezium & 1st metacarpal 1 to 12 12 trapezoid & 2nd metacarpal 1 to 10 10 capitate & hamate 0 to 10 11 scaphoid 0 to 8 9 lunate 0 to 8 9 triquetral & pisiform 0 to 8 9 radius 1 to 11 11 ulna 1 to 11 11 table 1. skeletal development sites (greulich and pyle, 1959) with the range of ordinal stages and the total number of stages used to calculate obtained level of development. stage “0” was added and defined as prior to the beginning of ossification. 6 dental anthropology 2020 │ volume 33 │ issue 01 opment at a site were scored as “non-observable” and excluded from further analysis. one author (almr) determined the level of attained dental development by visual examination of the permanent dentition as observed from lateral radiographs. the presence or absence of each tooth was noted, as was the stage of development. stages were determined using moorrees et al. (1963) stages from alqahtani et al.’s (2010) dental age estimation chart (table 2). due to the nature of lateral radiographs, differentiating the central versus lateral incisor was complicated and was solved by scoring only one, presumably the first central incisor in both the maxilla and mandible. although orthopantomograms are better suited for observing individual tooth development, the moorrees et al. (1963) method was developed based on lateral radiographs. furthermore, orthopantomograms are a more recent technological image and not commonly available in longitudinal studies such as the bolton-brush growth study. additional teeth scored included maxillary and mandibular canines, third and fourth premolars, as well as first, second, and third molars. siding was not possible, but only one tooth at each position was scored. when the quality of the radiograph or the angle prevented positively identifying a specific tooth, the tooth was scored as “non-observable.” intra-observer error to test for consistent scoring, a subset of 20% of the radiographs were randomly selected to form an intra-observer data subset. this subset of 78 handwrist radiographs and 80 lateral cephalograms were then scored a second time. the numeric and “non-observable” scores per hand-wrist location and tooth were included. all scores within the intra-observer subset were compared between rounds of observations using a weighted cohen’s kappa test (viera & garrett, 2005) using the statistical package r x64 3.2.3. data from repeat observations were used only for the intra-observer test and were not included in further analyses. developmental level scoring at each age, a composite score of percentage of attained skeletal and dental development was calculated for each individual. hand-wrist radiographs with fewer than seven scored sites were excluded from analysis. skeletal ordinal stages were converted into numbered levels (see table 1). ratios per site of percent development obtained were calculated based on the sites’ number of stages and then a composite score of average skeletal stage description stage description a-np 0 tooth absent, formation not yet begun. comparison between ages was used to distinguish from congenitally absent teeth. crc 6 crown complete with defined pulp roof ci 1 initial cusp formation ri 7 initial root formation cco 2 coalescence of cusps r ¼ 8 root length less than crown length. posterior teeth have visible bifurcation area. coc 3 cusp outline complete r ½ 9 root length equals crown length cr ½ 4 crown half complete with dentine formation r ¾ 10 three quarters of root length developed with diverge ends cr ¾ 5 crown three quarters complete rc+ 12 root length complete. with parallel ends or closed apex. table 2. dental development stages (moorrees et al., 1963; alqahtani et al., 2010) and their description. the number in the stage column is the number used to calculate level of obtained development. 7 dental anthropology 2020 │ volume 33 │ issue 01 development was calculated. similarly, lateral radiographs with fewer than eight scored teeth were excluded from analysis. the ordinal stages of dental development were converted into numbered levels (see table 2), ranging from zero for teeth whose formation had yet to begin, to 12 for completely formed teeth. numeric levels were then converted to percentages of completed development and a composite score of average dental development was calculated. the final sample sizes of usable radiographs per age varied from 92 to 97 for skeletal development and 90 to 97 for dental development (table 3a). determining quantile subgroups: delayed, average, and advanced quantiles used for analysis included individuals who were delayed, average, or advanced in their skeletal or dental development at age three, representing the range of normal variation. to define these quantiles, we divided the entire sample into two matched sets of five subgroups. each set of quantiles was defined either by the percentage of completed skeletal development (skeletal quantiles) or the percentage of completed dental development (dental quantiles) at age three. when defining each set of quantiles, the systems were considered independently. therefore, an individual’s ranking of skeletal development influenced only their classification in the skeletal quantiles and did not influence the placement in the dental quantiles, and vice versa. the delayed quantile includes those individuals who had achieved the least amount of development, those in the lowest 20th percentile. the average quantile included individuals in the middle quantile, those whose development was between the 40th and 60th percentiles. the advanced quantile contained the most developmentally advanced individuals, those in the highest 20th percentile. subsequent analyses comparing developmental trajectories were based on two sets of three quantiles: delayed, average, and advanced skeletal development quantiles; and delayed, average, and advanced dental quantiles. all six quantiles were of similar size (table 3b). although quantiles were defined based on one system at a time, some individuals fell in quantiles of interest for both systems (table 3c). by using these six quantiles, four questions could be examined: for quantiles based on skeletal development: 1) how do the skeletal developmental trajectories compare between skeletal quantiles? 2) how do the dental developmental trajectories compare between skeletal quantiles? for quantiles based on dental development: 1) how do the dental developmental trajectories compare between dental quantiles? 2) how do the skeletal developmental trajectories compare between dental quantiles? statistical analysis descriptive statistics were calculated for the total original sample and for each quantile of interest at all four ages. additionally, attained development composite scores were plotted against exact chronological age. for each plot, logistic growth curves (fox & weisberg, 2010) were calculated and added to the plots. repeated measure anova was used to test the significance of statistical models based on each question. these statistical models incorporated the composite score of obtained development (a) sample pre-quantiles assigned age dental skeletal both 3 90 92 84 6 93 97 90 9 97 97 95 12 97 95 92 all ages 83 84 72 (b) per quantile of interest by system delayed mean advanced skeletal development based quantiles (skeletal quantiles) 18 18 18 dental development based quantiles (dental quantiles) 19 18 19 (c) per quantiles of interest for both systems skeletal quantiles delayed mean advanced dental quantiles advanced 3 6 4 mean 3 1 4 delayed 5 1 5 table 3. sample sizes after percent of obtained development was calculated. (a) total sample size of usable radiographs prior to quantile assignment. (b) sample size per skeletal and dental quantiles of interest. (c) sample size of individuals who were in the quantiles of interest in both systems. 8 dental anthropology 2020 │ volume 33 │ issue 01 for a given system (development) as the dependent variable and individual (pt.id), chronological age (age), baseline quantile group (q.subgroup), and the interaction of age and baseline quantile group as the independent variables, with repeated measures by individual (pt. id). development ~ pt.id +age+ q.subgroup model 1 corresponds with the first question: how do the skeletal developmental trajectories compare between skeletal quantiles? therefore, in model 1 the dependent developmental variable is skeletal development, and the q.subgroup are the three skeletal baseline quantile groups. model 2 corresponds to the second question and uses dental development for the dependent variable, and uses the same three skeletal baseline quantile groups for the q.subgroup. this pattern continues through the remaining two questions. when the repeated measure anova showed the statistical model to be significant, a tukey’s hsd (honest significant difference) test was run for pairwise comparison of quantile groups. analyses were completed using r x64 3.2.3 and stata/ic 11.2 statistical programs. results weighted cohen’s kappa test (viera & garrett, 2005) of intra-observer error showed consistent agreement in development scores. for dental development, the weighted cohen’s kappa was 0.811, demonstrating almost perfect agreement, while the weighted cohen’s kappa for skeletal development was 0.792, demonstrating substantial agreement and falling just below the 0.81 cutoff for almost perfect agreement (landis & koch, 1977). in agreement with previous studies (cardoso, 2007b; flores-mir et al., 2005; lewis & garn, 1960), descriptive statistics show that, overall (table 4a), skeletal development is more variable than dental development at all ages (table 5a). however, this difference did not hold up for all quantiles of interest, as for some quantiles, the variation in dental development was greater than for skeletal. results for quantiles based on skeletal development for skeletal based quantiles, the descriptive statistics (table 4b) fail to demonstrate consistently greater skeletal development variation than dental (table 5b). at age three, the reverse is true for all three quantiles. the dental development continues to be more variable at age six for the average and advanced quantiles. at age nine, the dental variation is greater only for the advanced quantile, but at age 12, only the average quantile demonstrates higher dental variation than skeletal. these differences suggest that there are differences in skeletal and dental development between those who were delayed, average, or advanced in their skeletal development at age three. model 1: skeletal developmental trajectories of skeletal quantiles figure 1a depicts skeletal developmental trajectories of the three skeletal quantiles versus exact chronological age. the three lines represent the logistic growth curves per skeletal quantile. the difference in mean age per quantile decreases continuously between the delayed and advanced quantiles as the individuals age. despite the narrowing differences, the three quantiles continue to follow their own trajectories. a repeated measure anova was run on model 1, comparing the skeletal developmental trajectories of the three skeletal quantiles (table 6a). the model was found to be significant (f=179.43; p<0.0001). age, as well as the interaction of age and skeletal quantile, was also significant. the r-squared value for the model was 0.9869. based on the model’s significance, a tukey’s hsd pairwise comparison was run to test the effect each quantile’s pairing had on the complete model (table 6b). this test demonstrated that all three comparisons between the skeletal quantiles were significantly different in their mean scores. model 2: dental developmental trajectories of skeletal quantiles figure 1a and 1b depict the developmental trajectories versus exact chronological age of the same individuals within the skeletal quantiles of interest. however, while figure 1a compares the skeletal development, figure 1b compares the dental development. the trajectories of the delayed and average quantiles are similar and, in fact, cross over each other. a repeated measure anova was run on model q2, comparing the dental development of the three skeletal quantiles (table 7a). the model was significant (f=128.47; p<0.0001). the influence of age was significant in model 2, as it was in model 1. however, unlike model 1, the interaction between age and the skeletal quantiles was not significant (p=0.4578). the r-squared was 0.9822, which is slightly lower than that for model 1 yet still a high value. because the model was significant, a tukey’s hsd pairwise comparison was run (table 7b). the results of this test differ from those of model 1 in that not all the pairwise comparisons 9 dental anthropology 2020 │ volume 33 │ issue 01 table 4. descriptive statistics of the skeletal and dental development for the entire sample, (b) three skeletal quantiles of interest, and (c) the three dental quantiles of interest. (a) total sample’s development skeletal dental mean sd mean sd age 3 0.3226 0.0630 0.2762 0.0364 age 6 0.5372 0.0628 0.5199 0.0561 age 9 0.7083 0.0658 0.7326 0.0503 age 12 0.8906 0.0483 0.9107 0.0405 (b) skeletal based quantiles d e v e lo p m e n t delayed-skeletal average-skeletal advanced-skeletal s k e le ta l mean sd mean sd mean sd age 3 0.2424 0.0250 0.3146 0.0058 0.4170 0.0401 age 6 0.4654 0.0532 0.5521 0.0458 0.6059 0.0337 age 9 0.6585 0.0522 0.7174 0.0554 0.7815 0.0499 age 12 0.8890 0.0512 0.8976 0.0377 0.9081 0.0460 delayed-skeletal average-skeletal advanced-skeletal d e n ta l mean sd mean sd mean sd age 3 0.2758 0.0303 0.2613 0.0320 0.2819 0.0410 age 6 0.4987 0.0498 0.5154 0.0601 0.5486 0.0639 age 9 0.7265 0.0503 0.7145 0.0443 0.7527 0.0632 age 12 0.9022 0.0324 0.8995 0.0625 0.9281 0.0355 (c) dental based quantiles d e v e lo p m e n t delayed-dental average-dental advanced-dental d e n ta l mean sd mean sd mean sd age 3 0.2256 0.0182 0.2783 0.0053 0.3265 0.0219 age 6 0.4974 0.0270 0.5230 0.0568 0.5298 0.0648 age 9 0.7033 0.0424 0.7358 0.0525 0.7647 0.0517 age 12 0.9026 0.0529 0.9160 0.0362 0.9199 0.0469 delayed-dental average-dental advanced-dental s k e le ta l mean sd mean sd mean sd age 3 0.3153 0.0607 0.3181 0.0592 0.3274 0.0852 age 6 0.5348 0.0820 0.5237 0.0603 0.5335 0.0616 age 9 0.7100 0.0814 0.7006 0.0720 0.7135 0.0706 age 12 0.8716 0.0613 0.8912 0.0409 0.9128 0.0300 10 dental anthropology 2020 │ volume 33 │ issue 01 table 5. calculated difference of the variation (as measured by standard deviation) between skeletal and dental development. a) sd: ts – ts total sample: skeletal develop. – dental develop. age 3 0.0266 age 6 0.0066 age 9 0.0155 age 12 0.0078 (b) sd: q2 – q3 skeletal quantiles: skeletal develop. – dental develop. delayed average advanced age 3 -0.0053 -0.0261 -0.0009 age 6 0.0034 -0.0144 -0.0303 age 9 0.0018 0.0111 -0.0132 age 12 0.0188 -0.0247 0.0104 (c) sd: q4 – q1 dental quantiles: skeletal develop. – dental develop. delayed average advanced age 3 0.0426 0.0539 0.0632 age 6 0.0549 0.0035 -0.0032 age 9 0.0390 0.0196 0.0189 age 12 0.0084 0.0048 -0.0169 table 6. model 1: skeletal development between skeletal quantiles. pt.id: individual; age: patient’s chronological age; skeletal.q: patient’s skeletal quantile. (a) repeat measure anova number of observations =218 r-squared = 0.9869 root mse = 0.0305 adj r-squared = 0.9814 source partial ss df ms f prob > f model 10.7138 64 0.1674 179.43 0 pt.id 0.5387 55 0.0098 10.5 0 age 9.7514 3 3.2505 3483.98 0 skeletal.q 0 0 age # skeletal.q 0.1280 6 0.0213 22.87 0 residual 0.1427 153 0.0009 total 10.8565 217 0.0500 between-subjects error term: age # skeletal.q levels: 12 (6df) lowest b.s.e. variable: age covariance pooled over: skeletal.q (for repeated variable) repeated variable: pt.id (b) tukey’s hsd studentized range critical value (.05, 3, 153) = 3.3472 uses harmonic mean sample size = 72.608 quantile vs quantile quantile means mean dif hsd-test delayed vs average 0.5563 0.6174 0.0612 17.0724* delayed vs advanced 0.5563 0.6767 0.1205 33.6101* average vs advanced 0.6174 0.6767 0.0593 16.5377* figure 1. logistic growth curves of skeletal quantiles: chronological age versus development. plots of chronological age by proportion of completed skeletal (a) or dental (b) development based on skeletal development at age three, the delayed, average, and advanced skeletal quantiles. logistic growth curves depict the developmental trajectories taken by those within each quantile. 11 dental anthropology 2020 │ volume 33 │ issue 01 are significant. only those comparisons that include the advanced quantile are significant, while the interaction between the delayed and average quantiles is not. results for quantiles based on dental development the descriptive statistics of the dental based quantiles (see table 4c) demonstrate that, for the delayed and average quantiles, dental development is consistently less varied than skeletal development (see table 5c), as is predicted. however, the advanced quantile varies by age in terms of which systems’ development has greater variation. at ages three and nine the skeletal development is more varied, while ages six and 12 have greater variation in the dental development. model 1: dental developmental trajectories of dental quantiles in figure 2a, the dental developmental trajectories of the three dental quantiles versus the exact age is shown. model 3 is similar to model 1 in that the system’s development being measured (dental for model 3, skeletal for model 1) is the same as the system upon which the quantiles were defined. from age three to age 12, the difference in dental development between the delayed-dental quantile and the advanced-dental quantile decreases. however, the decrease does not occur continuously, as it does for model 1. the dental development of the three dental quantiles was compared by a repeated measure anova (table 8a). as was the case with models 1 and 2, model 3 was significant (f=154.32; p<0.0001). corresponding to the observed significance of model 1, in model 3 age was significant, as was the interaction of age and dental quantile. the r-squared was 0.9848. as model 3 was significant, tukey’s hsd was again run. the results of the tukey’s hsd demonstrated that all three pairwise comparisons between the dental quantiles were significant (table 8b). this consistent significance of the pairwise comparisons is similar to model 1, in which the skeletal development was compared between the skeletal quantiles. model 2: skeletal developmental trajectories of dental quantiles figure 2b depicts the skeletal developmental trajectories of those individuals whose dental development was delayed, average, or advanced at age three. this mixed combination of systems is similar to model 2, although model 4 includes the same individuals as model 3. the repeated measure anova of model 4 (table 9a) found that the model was again significant (f=98.95; p<0.0001). the pattern of significance for model 4 matches that of model 2. age was significant, while the interaction between age and dental quantile was not (p=0.39665). of the four models, model 4 has the lowest r-squared (0.9769), although the r-squared value is still quite high. tukey’s hsd was required as the model was significant (table 9b). of the pairwise comparisons in model 4, only that between the average and advanced quantiles was significant. the delayed quantile mean was not significantly different than either the average or advanced quantiles. discussion the null hypothesis, that the developmental trajectories do not vary between delayed, average, and advanced individuals, failed to be rejected univertable 7. model 2: dental development between skeletal quantiles. pt.id: individual; age: patient’s chronological age; skeletal.q: patient’s skeletal quantile. (a) repeat measure anova number of observations =214 r-squared = 0.9822 root mse = 0.0388 adj r-squared = 0.9746 source partial ss df ms f prob > f model 12.3599 64 0.1931 128.47 0 pt.id 0.2582 55 0.0047 3.12 0 age 11.9463 3 3.9821 2648.8 9 0 skeletal.q 0 0 age # skeletal.q 0.0086 6 0.0014 0.96 0.4578 residual 0.2240 149 0.0015 total 12.5839 213 0.0591 between-subjects error term: age # skeletal.q levels: 12 (6df) lowest b.s.e. variable: age covariance pooled over: skeletal.q (for repeated variable) repeated variable: pt.id (b) tukey’s hsd studentized range critical value (.05, 3, 149) = 3.3480 uses harmonic mean sample size = 71.292 quantile vs quantile quantile means mean dif hsd-test delayed vs average 0.6064 0.6030 0.0034 0.7330 delayed vs advanced 0.6064 0.6319 0.0255 5.5630* average vs advanced 0.6030 0.6319 0.0289 6.2960* 12 dental anthropology 2020 │ volume 33 │ issue 01 sally. when the quantiles were defined based on the skeletal system, the skeletal developmental trajectories clearly differ between the delayed, average, and advanced quantiles. this is evident in the continuously decreasing differences between the delayed and advanced quantiles, as depicted in figure 1a. the significance of the interaction terms in model 1 indicates that the trajectories are different; they are not parallel versions simply offset from each other. this means that the rates of skeletal development differ, as do the absolute agespecific developmental percentages quantiles. the null hypothesis was, therefore, rejected based on the significance of the tukey hsd test of model 1. however, when the dental development of these same individuals was considered in model 2, the three quantiles did not follow significantly different developmental trajectories; only the advanced quantile was significantly different from the other two. the non-significance of the interaction term from model 2’s repeated measure anova indicates that the trajectories are parallel. therefore, while the rate of dental development is similar for the three quantiles, those who were skeletally advanced begin and remain relatively advanced dentally. this difference in significance is unexpected. growth charts, such as those released by the world health organization (who) and center for disease control (cdc), show that percentiles diverge as individuals age (who multicenter growth reference study group, 2006). the greulich & pyle logarithmic development graphs are suggestive of different developmental trajectories (greulich & table 8. model 3: dental development between dental quantiles. pt.id: individual; age: patient’s chronological age; dental.q: patient’s dental quantile. (a) repeat measure anova number of observations =211 r-squared =0.9848 root mse =0.0361 adj r-squared =0.9784 source partial ss df ms f prob > f model 12.4365 62 0.2006 154.32 0 pt.id 0.2711 53 0.0051 3.94 0 age 12.0967 3 4.0322 3102.22 0 dental.q 0 0 age # dental.q 0.0363 6 0.0060 4.65 0.0002 residual 0.1924 148 0.0013 total 12.6289 210 0.0601 between-subjects error term: age # dental.q levels: 12 (6df) lowest b.s.e. variable: age covariance pooled over: dental.q (for repeated variable) repeated variable: pt.id (b) tukey’s hsd studentized range critical value (.05, 3, 148) = 3.3483 uses harmonic mean sample size = 70.33 quantile vs quantile quantile means mean dif hsd-test delayed vs average 0.5846 0.6146 0.0299 6.9620* delayed vs advanced 0.5846 0.6327 0.0480 11.1732* average vs advanced 0.6146 0.6327 0.0181 4.2112* table 9. model 4: skeletal development between dental quantile. pt.id: individual; age: patient’s chronological age; dental.q: patient’s dental quantile . (a) repeat measure anova number of observations = 208 r-squared = 0.9769 adj r-squared = 0.9670 root mse = 0.0399 source partial ss df ms f prob > f model 9.7891 62 0.1579 98.95 0 pt.id 0.6146 53 0.0116 7.27 0 age 8.9928 3 2.9976 1878.65 0 dental.q 0 0 age # dental.q 0.0100 6 0.0017 1.05 0.3965 residual 0.2314 145 0.0016 total 10.0205 207 0.0484 between-subjects error term: age # dental.q levels: 12 (6df) lowest b.s.e. variable: age covariance pooled over: dental.q (for repeated variable) repeated variable: pt.id (b) tukey’s hsd studentized range critical value (.05, 3, 145) = 3.3490 uses harmonic mean sample size = 69.33 quantile vs quantile quantile means mean dif hsd-test delayed vs average 0.6175 0.6056 0.0119 2.4799 delayed vs advanced 0.6175 0.6261 0.0087 1.8052 average vs advanced 0.6056 0.6261 0.0206 4.2851* 13 dental anthropology 2020 │ volume 33 │ issue 01 pyle, 1959), which also influenced the hypothesized difference between quantiles. if the two systems are correlated, and the body’s approach to the development of both systems is the same, then it would be expected that the developmental trajectories of the dental system would also be significantly different, given the skeletal system’s trajectories. that the dental system in general varies less than the skeletal system does not seem to be sufficient explanation for why the advanced quantile followed significantly different developmental trajectories than the delayed and average quantiles. from the analysis of dental quantiles, the null hypothesis again was rejected as the dental developmental trajectories (tukey hsd test of model 3) were all significantly different and not parallel. as with model 1, this finding is consistent with existing maturation charts such as those by moorrees et al. (1963). it is interesting and noteworthy that while the dental developmental trajectories of the dental quantiles (model 3) are all significantly different from one another, the delayed and average skeletal quantiles (model 2) do not follow significantly different dental developmental trajectories. differences in skeletal development among the dental quantiles also reject the null hypothesis, although only the average and advanced dental quantiles followed significantly different skeletal developmental trajectories from each other. as the interaction term from model 4 was not significant, it is apparent that these two quantiles followed different, yet parallel, trajectories. as depicted in figure 2b, the difference between the average and advanced quantiles, while significant, is not great. given this small difference, the variation of the delayed quantile shows an erratic pattern between the other two quantiles without being significantly different from either. while the advanced subgroup is the only one that was consistently different throughout the analyses, these four models demonstrate that the relative relationship between the skeletal and dental systems are not the same throughout the range of ivdt. this study did not take into consideration possible stressors that might influence the skeletal or dental development. it is possible that future research that considers such stressors will offer insight into possible tradeoffs occurring between the systems that might explain these unexpected results from skeletal based quantiles. conclusions this research has demonstrated the importance of considering the possibility that those individuals towards the extremes of normal ivdt may follow different developmental trajectories than is fully characterized by the sample mean. we have shown figure 2. logistic growth curves of dental quantiles: chronological age versus development. plots of chronological age by proportion of completed dental (a) or skeletal (b) development based on dental development at age three, the delayed, average, and advanced dental quantiles. logistic growth curves depict the developmental trajectories taken by those within each quantile. 14 dental anthropology 2020 │ volume 33 │ issue 01 that for skeletal and dental development, the trajectories are significantly different between those who are delayed, average, and advanced early in life. that this significance varies, and that the trajectories are occasionally parallel when the opposite system is considered, suggests that the relationship between the development of the skeletal and dental systems is more complicated than has been previously explored. it is important to note that while the skeletal and dental quantiles were assigned independently, there are 32 individuals who fall into the quantiles of interest for both systems (see table 3c). of these individuals, less than a third were classified in the same level of quantile for both systems (5 delayed, 1 average, 4 advanced). slightly over a quarter of the individuals who were delayed in one system were advanced in the other (3 delayed skeletal, 5 delayed dental). based on the plethora of research finding a positive, and often significant, correlation between the systems, this discrepancy of a quarter of the individuals is surprising and warrants further investigation. the variation between the systems’ developmental trajectories has been shown to vary between individuals who were delayed, average, or advanced in their development at an early age, and additional research is needed to further explore the full range of ivdt. acknowledgments the authors would like to thank the bolton-brush growth study for access to their collection. this research was funded by the university of new mexico’s evolutionary anthropology’s research development grant, and the office of graduate studies research, project, and travel grant. the authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article. references al-juboori, h. a., saloom, h. f., & al-bustani, a. 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(1998). earlier dental maturation: fact or fiction? the angle orthodontist, 68(6), 535– 538. nelson, s., hans, m. g., broadbent jr., b. h., & dean, d. (2000). the brush inquiry: an opportunity to investigate health outcomes in a wellcharacterized cohort. american journal of human biology, 12(1), 1–9. ogden, c. l., kuczmarski, r. j., flegal, k. m., mei, z., guo, s., wei, r., … johnson, c. l. (2002). centers for disease control and prevention 2000 growth charts for the united states: improvements to the 1977 national center for health statistics version. pediatrics, 109(1), 45– 60. rautman, a. l. m., & edgar, h. j. h. (2013). secular change in dental development in new mexican females. dental anthropology, 26(3), 31–37. ribot, i., & roberts, c. (1996). a study of nonspecific stress indicators and skeletal growth in two mediaeval subadult populations. journal of archaeological science, 23, 67–79. sachan, k., sharma, v., & tandon, p. (2011). a correlative study of dental age and skeletal maturation. indian journal of dental research, 22(6), 882. saglam, a. m. s., & gazilerli, ü. (2002). the relationship between dental and skeletal maturity. journal of orofacial orthopedics, 63, 454–462. stinson, s. (1985). sex differences in environmental sensitivity during growth and development. yearbook of physical anthropology, 28, 123–147. tanner, j. m. (1978). fetus into man: physical growth from conception to maturity. cambridge, massachusetts: harvard university press. viera, a. j., & garrett, j. m. (2005). understanding interobserver agreement: the kappa statistic. family medicine, 37(5), 360–363. waddington, c. h. (1942). canalization of development and the inheritance of acquired charac16 dental anthropology 2020 │ volume 33 │ issue 01 ters. nature, 150(3811), 563–565. wang, z., pang, x., wu, w., wang, j., wang, z., & wu, r. (2014). modeling phenotypic plasticity in growth trajectories: a statistical framework. evolution, 68(1), 81–91. who multicenter growth reference study group. (2006). who child growth standards: length/ height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age: methods and development. (p. 312) [technical]. retrieved from world health organization website: http://www.who.int/childgrowth/ standards/technical_report/en/ zhang, a., sayre, j. w., vachon, l., liu, b. j., & huang, h. k. (2009). racial differences in growth patterns of children assessed on the basis of bone age. radiology, 250(1), 228–235. harris 2011.4 59 tooth mineralization progresses in an invariant sequence, from crown tips through completion of the cementoenamel junction, and then through root formation, ending with closure of the root apices around the tooth’s neurovascular bundles (e.g., slavkin, 1974; corliss, 1976). moreover, the rate at which these processes of dentinogenesis and amelogenesis progress are well-regulated (e.g., pelsmaekers et al., 1997; parner et al., 2002; merwin and harris, 1998). tooth formation is better buffered than bone formation (greulich and pyle, 1959; garn et al., 1965), even though it can be modified by the environment (e.g., toverud, 1957; berkey et al., 2000; alvarez et al., 1988; alvarez, 1995). tooth formation is perhaps the least-biased tissue by which to estimate the biological age of a child (demirjian, 1986; harris, 1998). this often is done clinically using radiographs (e.g., liversidge, 2010) though direct examination can be used for archeological and forensic specimens (johanson, 1971; owsley and jantz, 1983). tooth formation can be measured on a continuous scale as the mineralized portion lengthens (e.g., liversidge and molleson, 2004; cardoso, 2009), but because this is timeintensive, and because of the morphological complexity of the tooth’s three dimensions, it generally is preferable to use visual criteria to determine the grade of development. grades are arbitrarily devised, with the intent of differentiating as many stages as possible (so finer distinctions can be made), but not so many that the observer cannot distinguish accurately between them. the two commonly used grading schemes are by moorrees, fanning and hunt (1963) with 14 stages and by demirjian, tanner and goldstein (1973) with 8 stages, though many other schemes have been developed (e.g., nolla, 1960; liliequist and lundbert, 1971; haavikko, 1973). the moorrees scheme is popular but has been criticized because it requires the scorer to estimate final size (e.g., root ½ formed, etc.). the demirjian system, in contrast, uses only observable criteria and now is perhaps the method of choice though, with only 8 grades, it lacks the potentially finer discrimination of moorrees’ 14 stages. a pertinent question is how to develop normative standards from the data regardless of the grading scheme, and, more specifically, what sort of data have been collected. that is, are the data from a longitudinal growth study where the same children are examined periodically, or are the data from a cross-sectional study where the children are only examined once? these two sources traditionally been used to create different kinds of data that estimate different features of the growth process. the purpose of this paper is to discuss the two kinds of estimates (smith (1991) describes others) and give an example of the practical differences. longitudinal studies there have only been a handful of studies where children—generally healthy and financially well-off—have been studied longitudinally, with multiple sorts of data collected at fixed intervals, generally 6 months or a year. data have consisted of anthropometrics, x-rays, dental casts, and various sorts of intellectual tests. well-known examples are the bolton-brush study in cleveland, ohio (behrents and broadbent, 1984), the denver child growth study, colorado (mccammon, 1970), the burlington growth study, a suburb of toronto, ontario (thompson and popovich, 1977), and the university school growth study from the university of michigan, ann arbor (riolo dental age: effects of estimating different events during mineralization edward f. harris* department of orthodontics, college of dentistry, university of tennessee health science center, memphis *correspondence to: edward f. harris, department of orthodontics, college of dentistry, university of tennessee, 870 union avenue, memphis, tn 38163 e-mail: eharris@uthsc.edu abstract the extent of tooth mineralization affords a practical method for assessing an individual’s biological age. dental age is useful for evaluating a child’s growth status, and for assessing the ages of subjects in anthropological, forensic, and medicolegal settings. historically, some data have been collected from serial studies (e.g., stuart’s harvard study, and the burlington study) while most studies are cross-sectional, where each child is examined just once. serial and cross-sectional studies traditionally have been used to estimate different sorts of information, namely the onset at a stage and the average age in a stage, respectively. this paper discusses the differences of the analyses, and then presents an empirical comparison of two large sets of data on the lower third molar in american whites, showing how the conventional uses of serial data—that estimate the onset of an event—precede the age of occurrence derived from cross-sectional data (age at stage). inter-group differences for tooth stages can exceed one year, so it is important to recognize the nature of the ‘standards’ available in the literature. dental anthropology 2011;24(2):59-63. 60 et al., 1974; moyers et al., 1976), though there are others (e.g., jones and bayley, 1941; sanin and savara, 1973). the complexity, commitment of money and manpower, and participant cooperation in such studies are enormous, and they are not likely to be repeated. with longitudinal studies, each child is examined periodically, and the interest has been on identifying the onset of an event. arbritrarily, consider moorrees’ stage 6 of crown completion (coded crc) for the upper second molar. each child‘s successive films are studied until that tooth exhibits crc (fig. 1). for example, examining a child, crc had not been achieved at time n (tn), but it is present at tn+1. the actual event occurred sometime between tn and tn+1, and the convention is to set the event at the midpoint between the two examinations, which is: tn+(tn+1 – tn)/2 it is unlikely that the achievement of crc occurred exactly at tn+1, and the midpoint between examinations is the best guess of when the true event occurred (dahlberg and menegaz-bock, 1958). the point is that this method estimates the onset of the event. in this case, at what chronological age does crc for the upper second molar occur in the sample under study? onset cannot be determined from cross-sectional data (what davenport (1931) termed “mass data”), but it can be approximated from the very low centiles of the age-at-occurrence. cross-sectional studies most studies do not have the luxury of following the same children over a span of time. in a typical anthropological setting, researchers examine subjects only once. it also is common to collect clinical records from a cohort of children where only one x-ray per child is available (e.g., harris and mckee, 1990; liversidge, 2010; tunc and koyuturk, 2008). consider stage crc for um2 again. perusal of a group of children will show that a) some have not yet attained this stage, b) some do exhibit the stage, and c) some have matured beyond this stage into a later stage (or completed formation). plotting the data by chronological age (fig. 1) shows a density plot that generally has a normal (gaussian) distribution: a few younger children (early maturers) will exhibit the stage, the stage commonly occurs along a certain age span, and a few, older children still retain this stage (slow maturers). this is a distribution of when—in this sample—crc is extant; smith (1991) terms this “age of subjects in a stage.” it is the average age when this stage of this tooth occurs in the sample. this statistic is not the same as the initiation of the stage as garnered from serial data. parenthetically, information for the age of occurrence can be gotten from serial data, but it seldom is, and there is a statistical problem scoring the same person multiple times. given these two kinds of data, how much difference does it make? is this an important distinction, or can it be ignored as a statistical nicety? it ought to make a pretty obvious difference. materials and methods the best known and one of the most popular ‘standards’ of tooth formation are those of moorrees, fanning and hunt (1963; harris and buck, 2002). this study combined data from jaw x-rays of children from a) harold c stuart’s longitudinal study of child growth and development (stuart et al., 1939; stuart and reed, 1959) and b) older children from the fels longitudinal study (yellow springs, ohio; roche, 1992). the onset of world war ii forced termination of the stuart study because most of the medical personnel entered the armed forces, so moorrees et al. collected their data on older children from the fels study. the x-rays were an oblique view of the jaws since the work predates the invention of panoramic x-ray machines (graber, 1967). edward hunt, the statistician on the project, used probit analysis to analyze the data (e.g., finney, 1971). this required plotting chronological age against the cumulative percentage of the children attaining the grade in question. in the early 1960s, this generally was determined visually fig. 1. schematic showing the age distribution of when children exhibit a given stage of tooth formation. the probability density plot generally is normally distributed, ranging from early-maturing children at the younger ages up to the average age, and then tapering down to the slower-maturing children who are the last to exhibit the grade before maturing into the next grade. the median age-at-occurrence is the vertical dashed line. serial studies can be used to estimate the onset of a grade (the distribution to the left of the diagram), but onset and median occurrence are quite different events. the hypothesized distribution of one stage is shown. the curve for onset is drawn smaller, but its age range can rival that of the age-at-occurrence, depending on the variability of dental ages in the sample. intra-individual variability is considerable, so when the average child’s tooth is at one stage, slow maturing children of the same chronological age will have stayed in a prior stage, and fast maturing children will be in a more advanced stage. e.f. harris 61 from the graphed data. unfortunately, how moorrees’ group actually performed the calculations is only described superficially. the data are provided separately by sex since garn et al. (1958), among others, had documented sexual dimorphism in mineralization, which parallels that of tooth emergence (cattell, 1928). moorrees et al. (1963) chose to present their data graphically, so the actual values have to be interpolated from the diagrams (harris and buck, 2002). the recent cohort described here consists of a crosssectional study of adolescents and young adults collected by the author who were phenotypically normal and were routine dental patients receiving treatment at the college of dentistry, university of tennessee, memphis. sample size was 1,870 (1,070 ♂, 800 ♀). these data were analyzed using survival analysis (cox and oakes, 1984; allison, 1995) to obtain the medians and standard errors for each of moorrees’ 14 stages by sex. these statistics are the average ages in a stage, not the onset of the stage. results the moorrees standards, published in 1963, were based on children largely from the 1930s, so it is anticipated that more recent children (i.e., the harris data)—with better nutrition (cdc, 1999) and lessened morbidity—would be growing at faster tempos. figure 2 shows the plots separately for boys and girls. the striking result is that the earlier, moorrees group consistently formed their m3s faster from childhood (around 10 years of age) through completion of the root apices in the early 20s. the obvious question is why the results are so different? the mean difference is 1.6 years for boys and 1.4 years for girls. the facile (and incorrect) explanation is that these mid-south children grew (and mineralized their lm3) much more slowly. as alluded to, the main reason for the difference is that two different sorts of data are being compared, namely fig. 2. plots of the chronolological ages at each of moorrees’ 14 stages for the mandibular third molar as estimated by moorrees et al. (1963) and from mid-south whites (this study). the means differ by more than a year on average, and the apparent but incorrect interpretation is that the moorrees sample developed faster. the real reason is that two different events are estimated; the moorres values are for the onset of the grade, while the harris estimates are for the average occurrence of the grade, which occur later. dental formation: kinds of data 62 the onset of a stage (moorrees) versus the average at which the stage occurs (harris), which is smith’s “age of subjects in a stage.” of course, the onset predates the average occurrence, and the span of time for occurrence is greater than the onset. false interpretations stem from confusing these different events. discussion there is a long-term interest in how children grow, and, specifically, how the dentition forms (krogman 1968; demirjian (1986). anthropologically, it is of interest whether some groups have a faster tempo of growth than others (perhaps the difference is adaptive). one wellknown example is between blacks and whites. using tooth eruption (gingival emergence), suk (1919) was probably the first to show that sub-saharan blacks grow faster than whites (sometimes strikingly so, see swinburne, 2005). boas (1933) disseminated suk’s findings in the literature. independently, steggerda and hill (1942) showed that eruption occurred earlier in american blacks than whites, and this difference has been confirmed and elaborated on by garn and coworkers (garn et al., 1972, 1973). since tooth emergence is tied to the degree of tooth formation (grøn, 1962), it follows that the two processes show the same ethnic differences. it seems most useful for such comparisons to use the median age-at-occurrence. this answers the question of whether the average-growing child from one group has a different rate of maturation than in a different group. clinically, a common use of dental age is to assess whether a child is growing at the “normal” rate: is his/ her degree of tooth formation consistent with the child’s chronological age? this is the basis of numerous studies of children with growth problems. since moorrees’ published standards (1963) are commonly cited and commonly available (the journal of dental research is an open-access journal), researchers are prone to use these ‘standards’ to evaluate the status of children of interest. since onset of a stage necessarily predates average occurrence of a stage (smith, 1991), a child’s degree of dental delay will be exaggerated when the moorrees ages at onset are used, and, if the child’ dental age is above-normal (midtbø and halse, 1992; hass et al., 2001), dental age will be under-estimated when using these ‘standards’ because the comparison is between different events. in sum, dental age is a practical method of gauging a child’s degree of maturity. because teeth form over a broad span of time—from the second trimester in utero through the onset of adulthood (lunt and law, 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re, van der linden fpgm, riolo ml, mcnamara ja jr. 1976. standards of human occlusal development. monograph no. 5, craniofacial growth series. ann arbor: center for human growth and development. owsley dw, jantz rl. 1983. formation of the permanent dentition in arikara indians: timing differences that affect dental age assessments. am j phys anthropol 61:467-471. parner et, heidmann jm, kjaer i, vaeth m, poulsen s. 2002. biological interpretation of the correlation of emergence times of permanent teeth. j dent res 81:451454. pelsmaekers b, loos r, carels c, derom c, vlietinck r. 1997. the genetic contribution to dental maturation. j dent res 76:1337-1340. riolo ml, moyers re, mcnamara ja jr, hunter ws. 1974. an atlas of craniofacial growth: cephalometric standards from the university school growth study, the university of michigan. monograph 2, craniofacial growth series. ann arbor: center for human growth and development, university of michigan. roche af. 1992. growth, maturation and 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monographs of the society for research in child development 4:serial no. 20. suk v. 1919. eruption and decay of permanent teeth in whites and negroes, with comparative remarks on other races. am j phys anthropol 2:351-388. swinburne m. 2005. advanced development. br dent j 198:628. thompson gw, popovich f. 1977. a longitudinal evaluation of the burlington growth centre data. j dent res 56 spec no:c71-78. toverud g. 1957. the influence of war and post-war conditions on the teeth of norwegian school children. ii. caries in the permanent teeth of children aged 7-8 and 12-13 years. milbank memorial fund quarterly 35:127196. tunc es, koyuturk ae. 2008.dental age assessment using demirjian’s method on northern turkish children. forensic sci int 175:23-26. dental formation: kinds of data smith and harris 2009.3 52 as is well known, the human mandible develops from the first branchial arches, and it ossifies before birth as separate left and right hemimandibles that meet ventrally at the mandibular symphysis (symphysis menti). overviews of the embryology of the mandible are provided in arey (1965), corliss (1976), scheuer and black (2000), and most textbooks on mammalian embryology. at birth (fig. 1), the mandibular midline is patent, though this suture normally fuses and is obliterated during the first year of life (fig. 2). after symphyseal fusion, the mandible is rigid, and masticatory forces from the working side are transmitted through the chin to the balancing side. the need for resistance to torsion has been cited as a cause of development of the uniquely human chin (e.g., sicher, 1947; dubrul and sicher, 1953; schwartz and tattersal, 2000), which occurs principally in adolescence (ricketts, 1972). rarely, the mandibular symphysis fails to fuse, and the present case report describes such an anomaly in a 4-year-old girl who also exhibits congenital absence of a primary incisor in combination with ankyloglossia. persistent patency of the symphysis menti is an easily observed condition in skeletal material, so this report may be of interest to skeletal biologists. moreover, it may stimulate readers to share similar findings. case description the subject is a healthy american black girl who was 4.0 years of age at examination. she was seen in a pediatric dental setting for routine restorative work. examination revealed 19 primary teeth with apparent congenital absence of the primary mandibular left central (tooth 71 in the fdi system; tooth o in the universal system). decay was seen clinically on the occlusal surface of all 8 primary molars and interproximally on bitewing radiographs. mesial caries can be seen radiographically on the primary left maxillary case report: patent mandibular symphysis with congenital absence and ankyloglossia ann s. smith and edward f. harris* department of pediatric dentistry, university of tennessee, memphis, tennessee central incisor (tooth f). the girl was treatment-planned for stainless steel crowns on the 8 primary molars, a mesial lingual resin on tooth f, and a lingual frenectomy. due to her young age, her multiple treatment needs, and her acute situational anxiety, it was recommended that the procedures be performed under general anesthesia. however, the patient moved out of state before treatment could be performed. the prominent frenum that ties the tip of the tongue to the floor of the mouth (and limits tongue mobility) is *correspondence to: edward f. harris, department of pediatric dentistry, university of tennessee, memphis, tennessee u.s.a. 38163 e-mail: eharris@utmem.edu fig. 1. occlusal view of the left and right hemimandibles of a near-term infant showing (a) the independent development of the two halves of the formative mandible and (b) the rough surfaces where they meet at the ventral midline. abstract the mandible develops prenatally as left and right halves (hemimandibles) that meet at a suture in the anterior midline. this suture normally is obliterated in the first year of life. we describe a 4-year-old girl in whom (a) this suture (symphysis menti) is only partially fused, (b) the primary lower left central incisor is congenitally absent (and also its permanent successor), and (c) there is pronounced ankyloglossia. these midline problems share a common etiology, namely incomplete fusion of the halves of the first branchial arch. no cause is suggested, but the embryological problem seems to stem from inadequate streaming together of the mesodermal cores of the first branchial arches. similar cases with the dental and bony aspects of this condition should be identifiable in skeletal remains. dental anthropology 2009;22(2):54-58. 53 had initiated fusion by 6 months of age. at 4 years of age, the girl’s suture described here is clearly delayed, if indeed fusion is still ongoing. ankyloglossia the tongue develops from the presumptive floor of the mouth (branchial arches i and iii), and endoderm immigrates around the developing tongue during postconception week 5. the apoptosis (selective cell death) of this endoderm is necessary for the mobile region of the tongue to be freed from the base (fig. 5). some of these cells persist in the midline and form the frenulum of the tongue, which is the membranous strand that ties the anterior, mobile portion of the tongue to the floor of the mouth. it is not uncommon for this tissue (the lingual frenum) to be prominent in infants and children, which can limit tongue mobility. this typically is of little concern because the frenulum regresses and stretches with age, particularly during infancy (e.g., wright, 1995; lalakea and messner, 2003). however, the prominence and extent of the ankyloglossia in this girl (figs. 3-4) clearly is outside of normal limits. this is obvious (fig. 4), where the girl is incapable of protruding here tongue because it is tethered to the floor of the mouth, with the frenum being continuous with the lingual gingiva (fig. 3). on the other hand, the girl’s labial vestibule (i.e., separation of the lower lip from the gingival ridge) is normal, and there is no hint of notching or clefting of either lip. true ankyloglossia (fusion of the whole tongue to the floor of the mouth) is a particularly rare event—to the point that clinician’s commonly use “ankyloglossia” to refer to the lesser “tongue tie” condition, where it fig. 2. lingual view of a deceased infant’s mandible showing incomplete but on-going fusion of the hemimandibles. fig. 3. extraoral photograph of the girl showing the partial ankyloglossia with prominent soft tissue attachment (frenum) encroaching on the space of the missing left central primary incisor. fig. 4. extraoral photograph of the girl showing how her ankyloglossia prevents normal tongue movement. an obvious feature in this girl (figs. 3 and 4), but what caught our attention was the persistent mandibular suture that is evident on x-ray (fig. 5). the hemimandibles are effectively fused together, but patent remnants of the suture are evident on the cranial and caudal aspects of the midline, and the open suture extends at least half a centimeter down through the mandibular alveolus. mandibular symphysis textbooks routinely note that the suture between the two hemimandibles fuses “within the first year of life,” though we have been unable to find more definitive statistics. molleson and cox (1993) studied the spitalfields collection and found that the two hemimandibles were always separate before 3 months of age, but most patent mandibular symphysis 54 is just the persistent midline fibrous band that limits tongue mobility (which can interfere with chewing, swallowing, and speech). for example, kotlow (1998) proposed a 5-grade scale to score the extent of ankyloglossia, ranging from a normal range of function (grade 0) up to “complete” ankyloglossia (grade iv) where less than 3 mm of the ventral tip of the tongue is mobile. this system may be useful clinically, but it ignores the developmental scenario where apoptosis (selective cell death) fails altogether and the tongue remains fused to the floor of the mouth. clinically, treatment of ankyloglossia (i.e., excision of the frenum) seems unwarranted in most cases. treatment should be limited to cases with documented speech, functional, occlusal or periodontal problems. the tongue is always short at birth, but, with growth, the tongue becomes longer and thinner at the tip. many cases are self-correcting (due to frenum stretching and tongue growth), which accounts for the comparatively low frequency of ankyloglossia in adults. congenital absence figures 3 and 6 show that the lower left primary central incisor is absent. this tooth normally emerges around 6 to 8 months of age (tanguay et al., 1984), and there is no suggestion from inspection of the alveolus that it might have been exfoliated in this 4-year old. moreover, the mother stated that this tooth was never present, so we conclude that the tooth is congenitally absent. the claim for absence of the primary left central incisor is supported by the congenital absence of its permanent successor (fig. 6). since a primary tooth’s successor develops from a lingual offshoot of the primary tooth bud (e.g., avery, 1994), the absence of a primary tooth greatly increases the risk of its successor also being absent (e.g., grahnén and granath, 1961). we suspect that it more than coincidental that the prominent frenum (fig. 3) is located right at the site of the incisor’s congenital absence. it is speculative, but the developmental disorder that failed to remove the presumptive frenum from the ventral midline may also be responsible for the incisor’s agenesis (or aborted development). dahlberg (1945, 1951) probably was the first to describe the reversal of the morphogenetic field in the mandibular incisors, where the central incisor is smaller, and more variable metrically and morphologically than the lateral incisor—but he provided no interpretation of the reversal, which is unique (all other fields exhibit greater variability of the distal tooth). other studies (reviewed in endo et al., 2007) suggest that simple hypodontia is tied to craniofacial issues of development, such as short cranial base and maxillary lengths, mandibular prognathism, and diminished anterior facial height. kjaer (1980) suggests that the poorer vascularity at the symphysis menti enhances the variability of the palatine process nasal septumfuture vestibule of mouth submandibular outgrowth parotid outgrowth occipital myotomes fig. 5. schematic cross-section of the developing embryonic mouth showing the pathways taken by the formative tissues. the epithelial surface shown as a solid line is ectodermal; the epithelial surface marked as a dashed line is endodermal. the cross-hatched epithelial area degenerates, forming the vestibule of the mouth and freeing the tongue from the floor of the mouth. modified from snell (1975). fig. 6. occlusal radiograph of the girl’s mandibular anterior region. the symphysis menti (top arrow) is patent for several millimeters in the cranial region of the midline. a 3-4 mm patency also is visible on the caudal margin of the symphysis (bottom arrow). the primary left central incisor is congenitally absent—as is its permanent successor—but the other three permanent incisors are forming and are completing crown formation. the missing permanent incisor would have been located almost directly beneath the open suture visible between the primary incisors. (note that orientation is reversed in this radiographic view, so the child’s left quadrant is to the right side of the picture.) a.s. smith and e.f. harris 55 central incisor. the present case may, however, reflect a local rather than systemic problem, where whatever caused the ankylosis (failure of apoptosis) also caused (a) failure of the incisor to form and (b) arrested fusion of the suture. these defects all involve formation of the first branchial arch, and their common locus at the midline may be due to inadequate mesodermal penetration into this arch’s midline (godbersen et al., 1987). similar cases (reviewed in eastlack et al., 2000) report additional midline defects in various individuals, such as dermoid cysts, ectopic salivary glands, bifid tongue (or aglossia), congenital absence of mandibular incisors, and cleft lower lip. again, these conditions suggest incomplete fusion of the first branchial arch as the common etiological problem (gardner and moss, 2005; mendis and moss, 2007). syndrome we initially speculated that this girl’s triad of (1) missing central incisor, (2) ankyloglossia and (3) persistent symphyseal suture constituted some sort of midline developmental defect, with incomplete left-right differentiation of the face. the symptoms probably involve a simpler, less dramatic situation. scrutiny of the girl’s maxilla revealed nothing unusual: both maxillary incisors (primary and permanent) are of normal size and morphology, and the intermaxillary suture is obvious (fig. 7). these left-right features argue against a problem with embryonic division as found in various sorts of holoprosencephaly (e.g., krauss, 2007; shiota et al. 2007). overview the case described here has three developmental defects, namely (1) pronounced ankyloglossia, (2) congenital absence of a primary lower incisor (and its permanent successor), and (3) incomplete fusion of the symphysis menti. the common etiology of these problems is speculated to be incomplete embryonic fusion of the left and right first branchial arches that should have occurred during week 5 postconception. these dental and bony anomalies are readily identifiable in the skeletal record, and we would be interested in hearing about similar cases. acknowledgement we are grateful to our former resident, dr. jonathan gooch, for bringing this case to our attention. literature cited arey lb. 1965. developmental anatomy: a textbook and laboratory manual of embryology. philadelphia: wb saunders company. avery jk. 1994. oral development and histology, 2nd ed. new york: thieme medical publishers, inc. corliss ce. 1976. patton’s human embryology: elements of clinical development. new york: mcgraw-hill book company. dahlberg aa. 1945. the changing dentition of man. j am dent assoc 32:676-690. dahlberg aa. 1951. the dentition of the american indian. in: laughlin ws, editor. the physical anthropology of the american indian. new york: viking fund inc., p 138-176. dubrul el, sicher h. 1953. the adaptive chin. springfield: charles c thomas. eastlack jp, howard rm, frieden ij. 2000. congenital midline cervical cleft: case report and review of the english language literature. pediatr dermatol 17:118-122. endo t, ozoe r, kojima k, shimooka s. 2007. congenitally missing mandibular incisors and mandibular symphysis morphology. angle orthod 2007 77:10791084. gardner ro, moss al. 2005. the congenital cervical midline cleft. case report and review of literature. br j plast surg 58:399-403. godbersen s, heckel v, wiedemann h-r. 1987. pterygium colli medianum and midline cervical cleft: midline anomalies in the sense of a developmental field defect. am j med genet 27:719–723. grahnén h, granath le. 1961. numerical variations in primary dentition and their correlation with the permanent dentition. odont revy 12:348-357. kjaer i. 1980. development of deciduous mandibular incisors related to developmental stages in the mandible. acta odontol scand 38:257-262. kotlow la. 1999. ankyloglossia (tongue-tie): a diagnostic and treatment quandary. quintessence int 30:259-262. krauss rs. 2007. holoprosencephaly: new models, new insights. expert rev mol med 9:1-17. fig. 7. occlusal radiograph of the girl’s maxilla showing complete tooth formation and eruption of the four primary incisors as well as mineralization of the four succedaneous incisors. patent mandibular symphysis 56 lalakea ml, messner ah. 2003. ankyloglossia: does it matter? pediatr clin north am 50:381-397. mendis d, moss al. 2007. case series: variations in the embryology of congenital midline cervical clefts. acta chir plast 49:71-74. molleson ti, cox m. 1993. the spitalfields project. vol. 2. the anthropology—the middling sort. research report 86. london: council for british archaeology. ricketts rm. 1972. a principle of arcical growth of the mandible. angle orthod 42:368-386. scheuer l, black s. 2000. developmental juvenile osteology. san diego: academic press. schwartz jh, tattersall i. 2000. the human chin revisited: what is it and who has it? j hum evol 2000;38:367409. sicher h. 1947. the growth of the mandible. am j orthod 43:123-128. shiota k, yamada s, komada m, ishibashi m. 2007. embryogenesis of holoprosencephaly. am j med genet a 143a:3079-3087. snell rs. 1975. clinical embryology for medical students, 2nd ed. boston: little, brown and company. sperber gh. 2001. craniofacial development. hamilton, ontario: bc decker inc. tanguay r, demirjian a, thibault hw. 1984. sexual dimorphism in the emergence of the deciduous teeth. j dent res 63:65-68. wright je. 1995. tongue-tie. j paediatr child health 31:276-278. a.s. smith and e.f. harris ioannou and henneberg 2016.1 41 dental anthropology 2016 │ volume 29 │ issue 01 keywords: disease; mercury; mandibular distomolar; morphology; supplemental teeth abstract congenital syphilis is a disease recognized for interfering with odontogenesis, producing specific dental characteristics including hutchinson’s incisor, moon’s molar, fournier’s molar and mulberry molar, while its past treatments including mercury are known to affect amelogenesis. supernumerary teeth, mainly associated with syndromes, are not commonly found in cases of congenital syphilis. a rare case of congenital syphilis in an individual (p000707) treated with mercury and a mandibular left fourth molar with normal morphology is presented. materials and methods: during a systematic examination of 28 skeletons with treponemal disease at the smithsonian museum in washington, dc, a supernumerary mandibular distomolar in one individual (p000707) was revealed. results: p000707 was an african american female, 26 years of age. dentition showed severe enamel hypoplasia of the maxillary and mandibular incisors, left canine, and upper first molars, consistent with the effects of treatment of congenital syphilis by mercurial compounds. crown of the left mandibular distomolar has typical molar morphology but is smaller in size than other permanent molars. arrangement of grooves resembles the +4 pattern, but is complex due to crenulation. oblique x-ray revealed that the fourth molar had one root with a pulp chamber extending towards the apex, suggesting taurodontism. no other distomolar teeth were present. conclusions: congenital syphilis and treatment containing mercury may not influence the development of supernumerary teeth due to: (1) the age at which the development of the fourth molar takes place, (2) the stage of the infection at the time of development and (3) the age at which treatments containing mercury are administered to patients with congenital syphilis. a rare case of congenital syphilis and a supernumerary fourth molar in an early 20th century african american woman stella ioannou a * and maciej henneberg b a biological anthropology and comparative anatomy research unit, the university of adelaide, adelaide, south australia, 5005 b institute of evolutionary medicine, university of zurich, zurich, switzerland, 8006 congenital syphilis is a disease caused by the transmission of treponema pallidum, from the mother to the fetus during pregnancy or at birth. in the neonate, various systems are affected. pathological signs appear in two stages of the disease. during the early stage, skeletal manifestations include periosteal reactions, osteochondritis, and osteomyelitis (hira et al., 1985; mclean, 1931) while during the late stage, signs can include frontal bossing, short maxilla, high palatal arch, saddle nose, higoumenakis’s sign, diaphysitis, metaphysitis and sabre shins (fiumara and lessell, 1970; rasool and giovender, 1989). however, the disease is most recognized for interfering with tooth formation (odontogenesis), producing certain characteristic teeth including hutchinson’s incisors, moon’s molar, fournier’s molar and the mulberry molar (fournier, 1886; hutchinson, 1863; karnosh, 1926; moon, 1884). even though these characteristic dental signs in congenital syphilis are seen in the permanent teeth (upper central incisors and first molars), which erupt approximately at 6-8 years of age, the dental abnormalities in these teeth are produced during the early stages of the disease, that is, once the infection and fever set in around the time of birth affecting initial crown formation. however, these dental abnormalities do not occur in all cases of congenital syphilis. the incidence of hutchinson’s incisors ranges from 30 to 50% (putkonen and paatero, 1961), while changes in first permanent molars range between 3 and 37% (berfield, 1971). in the past, mercury was used to treat congenital syphilis due to its antibacterial effects (hutchinson, 1874, 1878; warner, 1881). even though mercury was seen to benefit infected individuals, it was also seen to produce dental abnormalities that were different from *correspondence to: stella ioannou the university of adelaide, school of medicine adelaide 5005, south australia, australia email: stelzy_25@hotmail.com 42 dental anthropology 2016 │ volume 29 │ issue 01 those caused by the disease. hutchinson recognized that mercury affected amelogenesis resulting in severe enamel hypoplasia (hutchinson, 1878). treatments containing mercury were given to infants soon after birth, the time which enamel formation in permanent teeth begins. first permanent molars and incisors begin their formation around birth and this is when they are exposed to disease. mercury used to treat syphilitic infants continued for months after birth, severely affecting other tooth formation, depending on the length of time the treatment was administered (hutchinson, 1878). the abnormalities produced by congenital syphilis can be combined with the effects of treatment containing mercury (severe hypoplastic effects) (hutchinson, 1878; moon, 1884). treatment with mercury was commonly used in cases of congenital syphilis until the early 20th century. the whole suite of changes caused by congenital syphilis and treatments containing mercury have been discussed in detail (ioannou et al., 2016). supernumerary teeth have been associated with various syndromes and disorders including down’s and gardner’s, cleidocranial dysostosis, and cleft lip and palate (kumar and gopal, 2013; menezes and vieira, 2008; millhon and stafne, 1941; panjwani et al., 2011; sandler, 1951); however, they have not been described in detail in cases of congenital syphilis. supernumerary teeth are observed when more than 20 deciduous or 32 permanent teeth are present in an individual. they can erupt, remain unerupted, or become impacted (kara et al., 2012; mali et al., 2012). their appearance can be unilateral, bilateral, as a single tooth or in multiples (brinkmann et al., 2012; cavalcanti et al., 2011; harris and clark, 2008). the morphology of supernumerary teeth can vary in each individual from normal in shape and size, normal shape and reduced in size, conical in shape and abnormal in shape and reduced in size (harris and clark, 2008; kumar and gopal, 2013; rahnama et al., 2014). this paper presents a case of congenital syphilis in an african american woman dating from the early 20th century with a fourth mandibular molar. a focus will be made on the development of the fourth molar in the presence of a disease, which primarily affects dental development. materials and methods during a systematic examination of 28 skeletons held at the smithsonian museum in washington, dc, whose documentation stated that they had “treponemal or treponemal congenital” disease, a case of a supernumerary mandibular distomolar in one individual (p000707) was revealed. this individual was an african american female, who was born in 1903 and died of pulmonary tuberculosis in 1929, at 26 years of age. occlusal and oblique x-rays of the mandible were taken using a frankenstein unit to see whether a fourth molar was present on the right side. chemical analysis was performed to detect any levels of mercury. a bruker tracer iii-v handheld analyser was used on hypoplastic portions of the central and lateral incisors. the initial analysis used an allelements setting. the settings for the following test were elevated to (0.001” cu, 0.001” ti, 0.012” al filter at 40 kev/16 micro amps for 300 seconds, without vacuum) (ioannou et al., in press). results all maxillary permanent teeth were present, the central and lateral incisors, canines, premolars and all three molars. the enamel of the central incisors from the incisal third to the middle third of the crown appears mottled and thin (figure 1). the incisal third of the lateral incisors and left canine demonstrate the same mottled appearance and pitted enamel hypoplasia. deep pits are apparent toward the middle third of the crown of the central incisors and incisal third of the lateral incisors and canines. in addition to signs caused by mercury on the incisors and canines, other teeth display isolated hypoplastic pits. maxillary premolars are not affected. first permanent molars have abnormal occlusal surfaces, with cusps reduced in size and pitting hypoplasia, which is also consistent with the side effects of mercury (figure 2). diseased enamel is clearly demarcated from the healthy enamel on the cervical third of the crown. the morphology of the second and third permanent maxillary molars is normal with normal groove patterns, but there is some enamel pitting on the occlusal surface. mandibular permanent teeth include the central and lateral incisors, left and right canines, first and second premolars, second and third molars and the figure 1. the maxillary central and lateral incisors and left canine display hypoplastic enamel seen in patients with congenital syphilis treated with mercury. signs include thin enamel, pitted enamel hypoplasia (in some places very deep), and distinct demarcation separating diseased from healthy enamel. 43 dental anthropology 2016 │ volume 29 │ issue 01 distomolar. the first permanent molars were lost ante-mortem, possibly by extraction and their alveoli are completely healed. all mandibular incisors have mottled enamel (figure 3). the left and right second molars and the third left molar do not display severe hypoplasia, save for minor pitting. their occlusal surfaces are crenulated. the third permanent molar on the right side is represented by its roots only. the crown has broken off probably after its destruction by dental caries. on the left side, in the mandible, there is a fully erupted fourth molar (distomolar). its crown has normal molar morphology, but is smaller in size in comparison to the other permanent molars present. the arrangement of groves resembles the +4 pattern. however, the groove pattern is complex because of crenulation. entoconid, metaconid, hypoconid and protoconid are present, and it appears that there may be a narrow metaconulid, but crenulations make it difficult to determine (figure 4). an oblique x-ray of the mandible shows that the distomolar only has one root with a large pulp chamber extending far down towards its apex, suggesting a taurodont condition (figure 5). the third molar on the left is large and crowded between the distomolar and adjacent second molar. its crown is rotated approximately 10 degrees and tilted mesially. inspection of the x-ray does not reveal the presence of the antimeric distomolar (figure 6). all molar crowns appear crenulated. in the figure 2. occlusal view of the maxilla. first permanent molars have abnormal surfaces with small cusps and pitting hypoplasia figure 3. the anterior view of the mandibular incisors displaying enamel defects figure 4. occlusal surface of the mandible. the first permanent molars were lost ante-mortem. both second molars, the left third molar and left fourth molar are present. the right third molar is represented by its root only. the fourth molar displays normal molar morphology figure 5. oblique x-ray image of the mandible shows that the distomolar has only one root and that there is no antimeric distomolar. note the large extent of the pulp cavity in the distomolar, suggesting it is a taurodont molar. figure 6. x-ray of the occlusal view of the mandible does not show any evidence of a right fourth molar 44 dental anthropology 2016 │ volume 29 │ issue 01 post cranial skeleton, limited areas of nodular periosteal reaction were observed on the long bones including the right tibia, fibula, humeri, radius, ulnae, and femora, as well as the lateral surface of the left ilium. the left femur had lytic destruction along the lateral border of the head in the anterior aspect, “classic” striated periosteal reaction is not noticeable. discussion here we present a case of congenital syphilis with a supernumerary distomolar in an african american woman. although this condition is very rare during this time, it is probable, as one other case has been documented (jacobi et al., 1992). however, in this case, the dental abnormalities in p000707 indicate that she was treated with mercury soon after birth. changes in the morphology of the central maxillary incisors and left canine have enamel malformations that are compatible with dental abnormalities observed by hutchinson in patients with congenital syphilis administered treatment containing mercury (figure 7). crown formation of the central permanent incisors begins at approximately three to four months postnatally and is complete at approximately 4 to 5 years of age (nelson and ash jr, 2010). the specific changes in enamel caused by mercury are seen in one third of the crown, therefore, treatment would have started in the middle of the first year of life and ceased at approximately 2 years of age. similarly, severe enamel malformations are observed on the lateral incisors and canines that start forming later than the central incisors. the morphology of the maxillary first permanent molars demonstrates a normal groove pattern towards the mesial end of the crown, while the rest of crowns’ occlusal surfaces are reduced in size and hypoplastic. as the incisal third of the central incisors and a portion of the occlusal surface of the first permanent molars appears to be normal, the rest of the crown is affected, which may be an indication that the onset of the infection was late in relation to tooth development. congenital syphilis is known to produce specific dental abnormalities characteristic of the disease. however, it has been noted that in some cases of congenital syphilis, the classic dental changes that are usually observed such as hutchinson incisors, moon’s molar and fournier’s molars do not occur (švejda, 1952). hutchinson also observed and described certain dental abnormalities that occurred as an effect of treatments containing mercury (hutchinson, 1878). the dental abnormalities produced by the disease itself and treatments containing mercury were so distinct that hutchinson deemed it worthy to document and illustrate both as separate entities. it is worth noting that the crescentic notch that occurs in the maxillary central incisors of congenital syphilis patients is not observable if they were treated with mercury (hutchinson, 1878). the features observed in this p000707 are typical signs of teeth treated with mercury in patients with congenital syphilis (hutchinson, 1878; ioannou et al., 2016). while the results of the chemical analysis detected no levels of mercury, this neither confirms nor disproves that mercury was administered to this individual. various explanations could be considered. it is possible that the low levels of mercury in the enamel could not be detected by the equipment. another possible explanation for the lack of mercury detected could be due to the quick turnover rate of mercury in the body. the half-life of mercury ranges from 58 days for elemental mercury, 1-2 months for mercuric mercury (e.g. hgcl2), to 70-80 days for methylmercury (national research council (us) 2000). taking into account that this individual was treated with mercury for congenital syphilis in the early stages of life and died at 26 years of age, it is not abnormal to find extremely low levels of mercury. as indicated by hutchinson, if 648 mg (10 grains) of mercury were introduced in a body of a young individual, after 20 years only a minute quantity of mercury would remain (2.13*10-25mg). thus, it is more likely that a majority of the mercury would be cleared out, making it undetectable. figure 7. (a) anterior teeth of p000707 (b) patient treated with mercury as presented by hutchinson in 1878 (16 year old boy). both (a) and (b) display similarities in enamel abnormalities that occur as a result of treatments containing mercury. mercury would have been administered at a somewhat older age in p000707 than in hutchinson’s patient. hutchinson, (1878) p. 53, plate vi, items i (a) 45 dental anthropology 2016 │ volume 29 │ issue 01 other elements considered in the differential diagnosis include lead, zinc, copper and cadmium. high levels of lead can cause a decrease in microhardness of enamel (gerlach et al, 2002) but cannot cause malformations of the enamel (gerlach et al, 2002; youravong et al, 2005). fosse and berg-justesen (1977, 1978, 1978) and tvinnereim et al. (1999) examined concentrations of zinc, copper, and cadmium in teeth and bone in humans and mice and recorded the difference in concentration of these elements between enamel, dentin, and bone, but did not record any changes or malformations in enamel development. in relation to changes on the post cranial skeleton of p000707, since the individual died of tuberculosis, it is difficult to say which of those described pathological changes could be due to treponemal infection. the crown morphology of the distomolar is normal, unaffected by the disease, nor by treatments containing mercury. the smaller size of the distomolar is unlikely to be caused by congenital syphilis. clinical studies have shown that distomolars can demonstrate normal molar morphology, have as many as three to seven cusps and be reduced in size, in comparison to the other permanent molars (asrani et al., 2006; ceperuelo et al., 2015; kumar and gopal, 2013; ohata et al., 2013; shahzad and roth, 2012). the normal crown morphology in this case may be due to the time at which the development of the fourth molar began. it is the early stage of the disease that affects dental development. it occurs soon after birth and becomes the tertiary stage after several weeks. tertiary syphilis does not affect tooth development. the development of the third permanent molar begins at approximately 7 to 10 years of age and the tooth is fully erupted between the ages of 17 and early 20s (liversidge, 2015). it is possible that the fourth distomolar could have developed at the same age or even later. if the fourth molar had developed soon after the third molar, p000707 would have been in the tertiary stage of the disease; therefore, the disease could be asymptomatic and would not have affected amelogenesis or odontogenesis of the supernumerary fourth molar. however, it is possible that the fourth molar developed sooner. studies have shown that fourth molars can appear between the ages of 11 and 16 years (delgado et al., 2014; menardía-pejuan et al., 2000; orhana et al., 2006; vlaykov et al., 2015). it also appears common that distomolars demonstrate a single root, unlike the multiple roots observed in the other permanent molars (ceperuelo et al., 2015; ohata et al., 2013; rahnama et al., 2014). however, root formation can vary among individuals (complete with closed apex or incomplete) (ceperuelo et al., 2015; kokten et al., 2003; ohata et al., 2013). since the distomolar in this case is taurodontic, it is not possible to determine whether it had fused multiple roots or a single root because no separate root canals can be seen. at least formally, the root is a single unit. the cause of taurodontism is unclear. it has been associated with various syndromes (andersson et al., 2013; keeler, 1973; rajić and mestrović, 1998) and multiple theories have been suggested in the literature (alvesalo and varrela, 1991; witkop jr et al., 1988). in this case, it should be considered that the proportions of the root to crown size and pulp cavity to root canal volumes may have developed abnormally in the supernumerary, thus not normal, tooth without any special causes. the development of extra teeth is not fully understood, although multiple theories have been suggested such as hyperactivity within the dental lamina, and dichotomy of the tooth germ and these may be linked to genetic factors (kokten et al., 2003; kumar and gopal, 2013). for instance, martínez-gonzález et al. (2012) found them in 0.96%, shahzad and roth (2012) in 2.2% and kara et al. (2012) in 0.33%. it has been found that supernumerary molars were also more prevalent in african americans (6.4%), than in european americans (0.9%) (shahzad and roth, 2012). it has been suggested that african americans exhibit extra teeth more often than european americans (harris and clark, 2008), which may be related to african americans having larger dental arches and greater crown and root dimensions. this would increase a probability of the appearance of the distomolar in an african american suffering from congenital syphilis. conclusion a systemic infection such as congenital syphilis and its treatment with mercury may not influence the development of supernumerary teeth due to: (1) the age at which the development of the fourth molar takes place, (2) the stage of the infection at the time of development and (3) the age at which treatments containing mercury are administered to patients with congenital syphilis. acknowledgments the authors thank dr. david hunt for taking the xray images and rhonda coolidge for measuring mercury levels at the smithsonian museum support centre in washington, dc. literature cited alvesalo l, varrela j. 1991. taurodontism and the presence of an extra y chromosome: study of 47, xyy males and analytical review. hum biol 63:31-38. andersson e-m, axelsson s, gjolstad l-f, storhaug k. 2013. taurodontism: a minor diagnostic criterion in laurence-moon/bardet-biedl syndromes. acta odontol scand 71:1671–1674. 46 dental anthropology 2016 │ volume 29 │ issue 01 asrani mk, tarsariya vm, pathan jm. 2006. bilateral maxillary fourth and fifth molars: an unusual radiographic appearance. indian j dent res 27:103-105. bernfeld wk. 1971. hutchinson’s teeth and early treatment of congenital syphilis. brit j vener dis 47: 54–56. brinkmann jcs-bn, barona-dorado c, martínezrodriguez n, martín-ares m, martínezgonzález jm. 2012. nonsyndromic multiple hyperdontia in a series of 13 patients: epidemiologic and clinical considerations. j am dent assoc 143:e16-24. cavalcanti al, barros de alencar cr, guedes de carvalho neto l. 2011. bilateral maxillary and mandibular fourth molars: a case report and literature review. j investig clin dent 2:296–299. ceperuelo d, lozano m, duran-sindreu f, mercadé m. 2015. supernumerary fourth molar and dental pathologies in a chalcolithic individual from the el mirador cave site (sierra de atapuerca, burgos, spain). homo 66:15–26. delgado fe, youssef adm, jonasson t, landucci a, ulbrich lm, rodrigues de araujo m. 2014. multiple fourth molars: surgical treatment in young patient. rsbo 11:405-410. fiumara nj, lessell s. 1970. manifestations of late congenital syphilis: an analysis of 271 patients. arch dermatol 102:78-83. fosse g, berg justesen np. 1977. cadmium in deciduous teeth of norwegian children. int j environ stud 11:17-27. fosse g, berg justesen np. 1978. zinc and copper in bone and teeth of mice. int j environ stud 12:111 -120. fosse g, berg justesen np. 1978. zinc and copper in deciduous teeth of norwegian children. int j environ stud 13:19-34. fournier a. 1886. la syphilis héréditaire tardive paris: g. masson. p. 68-124. gerlach rf, cury ja, krug fj, line srp. 2002. effect of lead on dental enamel formation. toxicology 175:27-34. harris ef, clark ll. 2008. an epidemiological study of hyperdontia in american blacks and whites. angle orthod 78:460-465. hira sk, bhat gj, patel jb, din sn, attili rv, patel mi, baskarnathan s, hira rs, andu nn. 1985. early congenital syphilis: clinico-radiologic features in 202 patients. sex transm dis 12:177-183. hutchinson j. 1863. a clinical memoir on certain diseases of the eye and ear, consequent on inherited syphilis: with an appened chapter of commentaries to offspring, and its more remote consequences. london: john churchill. p. 203-206 hutchinson j. 1874. when and how to use mercury in syphilis. lancet 103:157-159. hutchinson j. 1878. illustrations of clinical surgery consisting of plates, photographs, woodcuts, diagrams etc. illustrating surgical diseases, symptoms and accidents, also operative and other methods of treatment, with descriptive letterpress. london: j. & a. churchill. p. 53-57. ioannou s, hunt d, coolidge r, hennegerg m. in press. dental characteristics of early 20th century cases of congenital syphilis. am j phys anthrop. ioannou s, sassani s, henneberg m, henneberg rj. 2016. diagnosing congenital syphilis using hutchinson’s method: differentiating between syphilitic, mercurial, and syphilitic-mercurial dental defects. am j phys anthropol 159:617629. jacobi kp, cook dc, corruccini rs, handler js. 1992. congenital syphilis in the past: slaves at newton plantation, barbados, west lndies. am j phys anthropol 89:145-158. kara m-is, aktan a-m, ay s, bereket c, şener is, bülbül m, ezirganlı se, polat h-b. 2012. characteristics of 351 supernumerary molar teeth in turkish population. med oral patol oral cir bucal 17:e395-400. karnosh lj. 1926. histopathology of syphilitic hypoplasia of the teeth. arch derm syphilol 13:25-42. keeler c. 1973. taurodont molars and shovel incisors in klinefelter's syndrome. j hered 64:234-236. kokten g, balcioglu h, buyukertan m. 2003. supernumerary fourth and fifth molars: a report of two cases. j contemp dent pract 4:67-76. kumar dk, gopal ks. 2013. an epidemiological study on supernumerary teeth: a survey on 5,000 people. j clin diagn res 7:1504-1507. liversidge hm. 2015. tooth eruption and timing. in: scott jd, editor. a companion to dental anthropology, 1st ed. new york: wiley & sons. p 159-171. mali s, karjodkar fr, sontakke s, sansare k. 2012. supernumerary teeth in non-syndromic patients. imaging sci dent 42:41-45. martínez-gonzález jm, cortés-bretón brinkmann j, calvo-guirado jl, arias irimia o, baronadorado c. 2012. clinical epidemiological analysis of 173 supernumerary molars. acta odontol scand, 70:398-404. mclean s. 1931. ii. the correlation of the roentgenographic and pathologic aspect of congenital osseous syphilis. am j dis child 41:363-395. menardía-pejuan v, berini-aytes l, gay-escoda c. 2000. supernumerary molars: a review of 53 cases. bull group int rech sci stomatol odontol 42:101-105. menezes r, vieira ar. 2008. dental anomalies as part 47 dental anthropology 2016 │ volume 29 │ issue 01 of the cleft spectrum. cleft palate craniofac j 45:414-419. millhon ja, stafne ec. 1941. incidence of supernumerary and congenitally missing lateral incisor teeth in eighty-one cases of harelip and cleft palate. am j orthod oral surg 27. moon h. 1884. dental surgery. in: bryant t, editor. a manual for the practice of surgery. london: j & a churchill. p 637-674. nelson sj, ash jr mm. 2010. wheeler's dental anatomy, physiology and occlusion, 9th ed ed. st louis: saunders elsevier. p. 31 ohata h, hayashi k, iwamoto m, muramatsu k, watanabe a, narita m, suga k, takano n, shibahara t. 2013. three cases of distomolars. bull tokyo dent coll 54:259-264 orhana ai, özer l, orhan k. 2006. familial occurrence of nonsyndromal multiple supernumerary teeth: a rare condition. angle orthod 76:891-897. panjwani s, bagewadi a, keluskar v, arora s. 2011. gardner’s syndrome. j clin imaging sci 1:1-4. putkonen t, paatero yv. 1961. x-ray photography of unerupted permanent teeth in congenital syphilis. brit j vener dis 37: 190–196. rahnama m, szyszkowska a, pulawska m, szczerbagwozdz j. 2014. a rare case of retained fourth molar teeth in maxilla and mandible. case report curr issues pharm med sci 27:118-120. rajić z, mestrović sr. 1998. taurodontism in down’s syndrome. coll antropol. 22: 63-67. rasool mn, giovender s. 1989. the skeletal manifestations of congenital syphilis. a review of 197 cases. bone joint j 71-b:752-755. sandler hc. 1951. cleidocranial dysostosis in four siblings. am j orthod 37:584-593. shahzad km, roth le. 2012. prevalence and management of fourth molars: a retrospective study and literature review. j oral maxillofac surg 70:272– 275. švejda j. 1952. zmeny na zubech pri kongenitalni syfilis. cesk stomatol 52:321–341. tvinnereim hm, eide r, riise t, fosse g, wesenberg gr. 1999. zinc in primary teeth from children in norway. sci total environ 226:201-212 vlaykov a, sharlanov d, vicheva d. 2015. fourth mandibular molar in a pediatric patient – case report. rom j rhinolo 5:229-231. warner f. 1881. east london hospital for children: cases of congenital syphilis lancet 117:173-174. witkop jr cj, keenan km, červenka j, jaspers mt. 1988. taurodontism: an anomaly of teeth reflecting disruptive developmental homeostasis. am j med genet 31:85-97. youravong n, chongsuvivatwong v, teanpaisan r, geater af, dietz w, dahlén, g, norén, jg.2005. morphology of enamel in primary teeth from children in thailand exposed to environmental lead. sci total environ 348: 73–81. 21 dental anthropology 2021 │ volume 34│ issue 02 the prevalence and possible causes of third molar agenesis in post-medieval chichester devyn caldwell 1* 1 no affiliation third molars are the last permanent tooth to develop, the most variable in size and morphology, and are also the most commonly congenitally absent tooth. according to sujon et al. (2016), approximately 50% of modern (20th century onwards) human third molars are anomalous, either unerupted, partially erupted or absent. congenital absence is known as dental agenesis, which results from a developmental anomaly in the dental epithelium or the underlying mesenchyme (bhutta et al., 2014). grewal’s (1962) analysis of agenesis in the third molars of mice revealed that congenitally absent teeth begin as tooth germs but growth formation ceases at or before the cap stage of development, at which point the tooth germ resorbs. it may occur unilaterally, bilaterally, in combinations of three teeth, or completely, with all four absent. in their meta-analysis of modern data, carter & worthington (2015) found that 22.63% of people worldwide have some degree of third molar agenesis. the samples included in their analysis were gathered from various ethnicities and socioeconomic groups, with prevalence ranging from 5.32% 56.0%. the exact etiology of third molar agenesis is unknown, but a genetic component is well established (carter & worthington, 2015; frazierbowers et al., 2002), and it is thought that delayed growth or a lack of space in the jaw may result in epigenetic absence (anderson & popovich, 1981; kajii et al., 2004; suri et al., 2004). disease and nutrition have also been shown to affect the eruption and formation of third molars (anderson & popovich, 1981; garn et al., 1961; suri et al., 2004), adding to the already complex etiology of this trait. grüneberg’s (1951) experiments with mice indicate that agenesis is the phenotypic result of the extreme end of a size continuum. mice with absent third molars more often displayed small and variable remaining third molars, and as the dental lamina became smaller, the more likely growth and tooth formation were to cease development and resorb. it has frequently been reported that third molar agenesis occurs more often in modern populations than in the past (alam et al., 2014; kajii et al., 2004), abstract third molar agenesis is a dental anomaly that occurs in approximately 25% of people worldwide and results in the complete absence of one or more of the third molars. a rise in the prevalence of congenitally absent third molars has been noted in modern clinical data, and it has been proposed as an evolutionary step in the dental reduction of the human dentition. whilst research has been conducted in extant cohorts, relatively little has been published on third molar agenesis in archaeological assemblages. a post-medieval assemblage (ad 1550-1850), from chichester, united kingdom, was visually and radiographically analyzed to determine the prevalence of this anomaly. mesiodistal and buccolingual measurements were taken on retained third molars to determine if there was an association between agenesis and reduced tooth size. prevalence of agenesis was found to be comparatively high (42.7%) relative to contemporary and modern european samples, and tooth size reduction was documented. consequently, it can be said that high rates of third molar agenesis are not simply a modern clinical phenomenon, as many prevalence rates in recent populations are lower. temporal and regional patterns are, therefore, unclear. in order to better understand the trajectory and evolution of this anomaly, more archaeological assemblages ought to be examined. *correspondence to: devyn caldwell no current affiliation e-mail: dmcaldwe@ualberta.ca keywords: dental anomalies, hypodontia, dental reduction, post-medieval 22 dental anthropology 2021 │ volume 34│ issue 02 with some claiming the third molar is likely to disappear from the human dentition altogether (raloti et al., 2013). a general reduction in tooth size has taken place throughout hominid evolution, with a rapid reduction in size occurring in the upper palaeolithic (50,000 – 10,000 ya) and again in the early holocene (10,000 8,000 ya) (hillson, 2005). while the impetus behind these changes is unclear, many associate the diminution of teeth with the atrophy of the masticatory complex due to increasingly soft diets, advancement of food processing techniques, and the diminished use of the mouth as a tool (brace et al., 1987; carlson & van gerven, 1977). the agriculturalization that took hold in the early holocene is thought to have furthered this trend in dental reduction, leading to what may be a further evolutionary step in dental reduction, the congenital loss of the third molar (sengupta et al., 1999). in this study, the past prevalence of third molar agenesis is examined in a post-medieval assemblage from chichester, providing new insights into patterns in agenesis and the role of dental size reduction and its occurrence. this investigation will also test whether this anomaly represents a recent secular trend and will add to our limited understanding of third molar agenesis in archaeological assemblages. materials the skeletal assemblage under analysis comes from the litten cemetery at eastgate square in chichester, west sussex. chichester has a long history of occupation, with evidence of roman defensive ditches found at the litten cemetery (hart, 2012), and continuous settlements recorded from the anglo-saxon period onwards (dhaliwal et al., 2019). in the later medieval period (14th century), chichester flourished as one of the more important ports in the country, with dominance over the wool trade and a strong agricultural economy (hart, 2012). a grain-based economy continued in the post-medieval period (1550-1850), although the town’s import declined as the wool trade waned. chichester also appears to have experienced a population surge between 1670-1801, with the number of inhabitants doubling from 2,400 to 4,752 due to increasing trade with london and other domestic markets (dhaliwal et al., 2019). this assemblage was excavated from a cemetery that seems to have been established in the 12th century with the construction of the chapel and altar of st. michael, which are no longer standing. interment officially ceased in 1859, although family plots remained active until the end of the 19th century (hart, 2012). the vast majority (66%) of human remains recovered date to the post-medieval period and represent a range of social strata, with the bulk of individuals (1,365), both from the medieval and postmedieval periods, buried in the simple shroud style (rando, 2016). in the present study, only postmedieval skeletons were analyzed for third molar agenesis. excavation of the site began in advance of its redevelopment, with 93 burials excavated by preconstruct archaeology ltd. (pca) in 2005 and 2006, and the remaining 1637 skeletons excavated by archaeology south-east (ase) between august of 2011 and january of 2012 (hart, 2012). four hundred and thirty skeletons from these excavations that have been retained for analysis at the university college london institute of archaeology due to high preservation levels or presence of pathological conditions. of these skeletons, 311 matched the preservation levels required (alveolar bone and dentition present) to warrant examination and only 116 had a minimal level of antemortem tooth loss that allowed for inclusion in this study. of these 116 skeletons, 89 had complete dentitions without any data missing. the remaining skeletons had missing data in either one (n=18) or two (n=9) of the dental quadrants. these skeletons were incorporated into the analysis when the lack of data did not affect the results (see below). in total, 46 males, 36 females and 34 skeletons of indeterminate sex were analyzed, comprising 83 adults and 33 subadults. methods selection, visual assessment, aging and sex estimation skeletons were carefully selected according to a set of criteria designed to minimize the effects of antemortem tooth loss. skeletons with fewer than four teeth lost antemortem were included in the analysis. in addition, only skeletons of a maximum age of a pubic symphysis phase 4 (brooks & suchey, 1990) and a auricular surface phase 4 (lovejoy et al., 1985) were incorporated in order to mitigate a greater risk for antemortem tooth loss with increasing age. the age at which third molars initiate crown formation varies more than any other tooth (alqahtani et al., 2010). alqahtani et al. (2010) reported a median dental age of 8.5 years for the initiation of crown development, and ubelaker (1989) provides a dental age of 10 years +/30 months for the initiation of crown mineralisation in both the maxillary and mandibular third molars. in this 23 dental anthropology 2021 │ volume 34│ issue 02 study, only subadults with a minimum dental age of 12.5 years were included, following the dental age categories established by alqahtani et al. (2010). according to garn et al. (1963), 99% of third molars begin their cusp mineralisation by the age of 14 years. however, due to the relatively small number of individuals that fit the criteria for analysis in this assemblage, the dental development stage of 12.5 years, defined by alqahtani et al. (2010), was selected as a minimum in order to maximize the available data. mandibles and maxillae were visually observed for the presence or absence of third molars using the following criteria to determine a lack of agenesis: the tooth is in the alveolus. the tooth was lost post-mortem, with a welldefined alveolus present. the tooth was lost antemortem but the alveolus is still in the process of resorbing, and no other pathological or taphonomic process could be responsible for the feature. the second molar in the particular quadrant has an identifiable distal approximal wear facet (indicating it had once been in contact with a third molar). an unerupted or impacted third molar is visible through radiographic analysis. third molar agenesis was diagnosed based on the absence of these criteria. if the maxillae or mandible met these requirements it was x-rayed to ensure that the third molar was not impacted, developing within the crypt, or had failed to erupt. if radiographic analysis did not reveal a third molar it was therefore determined to be congenitally absent. impaction was assessed based on abnormal angulation of the tooth in the alveolus or crypt (after raloti et al., 2013). sex determination was used to examine differences in size or agenesis prevalence. this was based on a combined assessment of pelvic morphological traits (after phenice, 1969), including the greater sciatic notch and composite arch (after bruzek, 2002), as well as measurements of the proximal humeral and femoral heads (maximum diameters after bass, 1995) and an assessment of the sexually dimorphic features of the skull (after ubelaker, 1989). the latter two methods were only employed if the features of the pelvis were slightly ambiguous, or if the pelvic bones were missing or too poorly preserved. the dimorphic traits of the pelvis are generally regarded to be more reliable indicators of sex than features of the skull (bruzek, 2002). the skeletons were assigned sex of male, possible male, indeterminate, possible female, and female. however, due to the small size of the sample possible males and possible females were collated with the respective sex. measurements measurements of third molars were taken in accordance with the cervical method developed by hillson et al. (2005) using specialized paleo-tech calipers (also developed by hillson and colleagues, 2005). cervical measurements are usually not affected by the level of crown wear, and as individuals with an advanced age were not included, tooth wear on third molars was generally not an issue. individuals with carious lesions affecting the crown could also be included. mesiodistal measurements were taken by placing the tips of the calipers on the mesial and distal enamel, just occlusal to the cervico-enamel junction (cej) and at the midpoint between the buccal and lingual sides of the tooth (see hillson et al., 2005). buccolingual measurements were also taken on the buccal and lingual surface at the midpoint of the enamel, slightly occlusal of the cej, between the mesial and distal surfaces of the tooth. it is important to note that these measurements were taken at the midpoints and are not maximum measurements, however, if an enamel extension was present at the midpoint, the tip of the caliper was placed at whichever side of the extension provided the maximum measurement for the midpoint, following hillson et al. (2005). the tips of the calipers that meet end-to-end were used with loose teeth and for the buccolingual measurements of teeth in the alveoli whenever possible. the caliper tips that meet at an angle were most useful for the mesiodistal measurements of teeth fixed in alveoli, and for the upper third molars, this measurement was approached lingually as these teeth tend to taper lingually, thereby ensuring a precise measurement. analysis interand intraobserver error tests were performed to ensure reproducibility and accuracy of results. third molars, especially those in the upper dentition, have a variable morphology and can be difficult to measure due to their irregular and oblong crown morphology (hillson et al., 2005). however, by ensuring the measurements are taken at the midpoint on the cej through careful and methodical application of technique, it is possible to achieve consistent results. two observers unfamiliar with measurement technique of hillson et al. (2005) took mesiodistal and buccolingual measure24 dental anthropology 2021 │ volume 34│ issue 02 ments on the same set of ten third molars (five upper and five lower) following the system described above. the values were then compared using spss 21 software to determine mean difference and 95% confidence interval (ci). the buccolingual measurements with observer 2 differed by as much as 0.5 mm, with one measurement revealing a 0.88 mm difference. however, the measurements of observer 1 closely resembled those of the researcher and therefore these differences were not explored further. in addition, observer 1 frequently reported slightly lower measurements than those of the researcher, most probably due to measurements taken on the cej or on the root surface, rather than on the enamel slightly occlusal to the cej. intra-observer tests for mesiodistal measurements (md=-0.098, sd=0.13481) remained close to ±0.2 mm, a range ideal for tooth measurements, but the range for buccolingual measurements was slightly higher (md=0.027, sd=0.21103). to correct for this, a larger sample size should be used in future studies in order to determine if the degree of error is acceptable. spss 21 statistics software was used to assess the prevalence of third molar agenesis in the chichester assemblage and analyze patterns within the sample. the data were divided into three groups: no data missing, one quadrant missing, and two quadrants missing. it is ideal to collect data on complete remains, but information was recorded on all three groups in order to gain as much data as possible. t-tests were performed to determine whether sizes differences exist in the mesiodistal and buccolingual measurements of third molars between those with and without third molar agenesis. difference in sizes between males and females were also compared statistically to determine the impact of sexual dimorphism on the results. following this test, males and females were analyzed separately for size differences in third molars. t-tests were also used to determine if significant differences in size existed between the various distributions and patterns of third molar agenesis. results the total prevalence of third molar agenesis in adult and subadult skeletons in the chichester cohort with data present for all dental quadrants is 42.7% (n=38/89). when incorporating those with data missing from one quadrant the prevalence falls to 40.2% (n=43/107) and is slightly higher when including those with missing data in two quadrants at 41.4% (n=48/116) (table 1). subadults with complete data yielded a prevalence of 45.8% (n=11/24), and this remained consistent at 45.5% agenesis n percent 95% ci skeletons with no missing data absent 51 57.3 ± 10.28 present 38 42.7 ± 10.28 total 89 100 including those with data missing from one dental quadrant* absent 64 59.8 ± 9.29 present 43 40.2 ± 9.29 total 107 100 including those with data missing from one and two dental quadrants* absent 68 58.6 ± 8.96 present 48 41.4 ± 8.96 total 116 100 table 1. agenesis prevalence recorded for all skeletons, separated into groups defined on the inclusion of missing data. agenesis n percent 95% ci skeletons with no missing data absent 13 54.2 ± 19.93 present 11 45.8 ± 19.93 total 24 100 including those with data missing from one dental quadrant absent 17 56.7 ± 17.73 present 13 43.3 ± 17.73 total 30 100 including those with data missing from one and two dental quadrants absent 18 58.6 ± 17.60 present 15 45.5 ± 17.60 total 33 100 table 2. agenesis prevalence recorded for subadult skeletons, separated into groups defined on the inclusion of missing data. *due to the small number of individuals in the assemblage, the inclusion of individuals with data missing was explored. no significant differences were found between prevalence in any of the groups, and it is therefore acceptable to use individuals with data missing as representative of the assemblage. 25 dental anthropology 2021 │ volume 34│ issue 02 (n=15/33) when subadult individuals with data missing were included (table 2). subadult prevalence is higher, but not significantly greater, χ2 (1, n=89) = 0.13, p = 0.72, than the 41.5% prevalence among adults with complete data in this assemblage (n=27/65) (table 3). when adults with one (n=30/77) and two (n=33/83) dental quadrants of data missing were included, this lowered the prevalence of agenesis to 39.0% and 39.8%, respectively, although the difference between adult and subadult prevalence remained statistically nonsignificant, χ2 (1, n=107) = 0.17, p = 0.68, and χ2 (1, n=116) = 0.32, p = 0.57. males in this assemblage show a 38.9% prevalence of agenesis (n=14/36), whereas females express a prevalence of 39.3% of third molar agenesis (n=11/28). third molar agenesis in the maxilla was less common than third molar agenesis in the mandible, and the right side was more frequently affected by agenesis than the left (table 4). the number of teeth missing followed a pattern in frequency of two, one, three, four, with agenesis of two molars occurring almost twice as frequent as one, and the absence of three and four was less agenesis n percent 95% ci skeletons with no missing data absent 38 58.5 ± 11.98 present 27 41.5 ± 11.98 total 65 100 including those with data missing from one dental quadrant absent 47 61.0 ± 10.89 present 30 39.0 ± 10.89 total 77 100 including those with data missing from one and two dental quadrants absent 50 60.2 ± 10.53 present 33 39.8 ± 10.53 total 83 100 table 3. agenesis prevalence recorded for adult skeletons, separated into groups defined on the inclusion of missing data. males females total (including indeterminate sex) right left total right left total right left total maxilla 9 6 15 6 4 10 21 17 38 (46%) mandible 7 8 15 7 7 14 23 22 45 (54%) total 16 14 30 13 11 24 44 39 83 table 4. the distribution of third molar agenesis between males, females, and the total assemblage, on the right and left sides and in the maxilla and mandible. figure 1. the frequencies in the number of third molars congenitally absent in individuals with agenesis and all data present in this assemblage. two third molars absent occur much more often in this assemblage than one third molar absent, and three and four are least common. 26 dental anthropology 2021 │ volume 34│ issue 02 common (figure 1). bilateral agenesis (figure 2) occurred more frequently than unilateral, or both unilateral and bilateral agenesis in one dentition, for example if unilateral agenesis occurred in the upper arcade and bilateral agenesis in the lower arcade (table 5). significant differences in tooth size were found between male and female third molars in this assemblage. the buccolingual dimensions of the ulm3, urm3, lrm3 and the mesiodistal dimensions of urm3, llm3 and lrm3 (table 6) produced significant differences between sexes, with mean male measurements being larger. two significant differences (p < 0.05) were found in the buccolingual dimensions of the ulm3 (p = 0.048, 95% ci [-1.04, -.005]) and urm3 (p = 0.009, 95% ci [-1.15, -.17]), in which those individuals with agenesis showed reduced dimensions compared to individuals without third molar agenesis (table 7). when separated by sex, only males with agenesis retained a significant reduction in size (p < 0.05) in the ulm3 buccolingual dimension (table 8). third molars visibly reduced in size and complexity, known as “vestigial third molars” as described by nanda (1954), were noted in seven skeletons that also displayed third molar agenesis. t-tests did not reveal significant differences in the mesiodistal or buccolingual dimensions of third molars between individuals with one or three third molars congenitally absent, bilateral maxillary or mandibular agenesis, and those without agenesis. there was a significant difference (p > 0.05) in the mesiodistal dimensions of llm3 in those with three third molars missing and bilateral maxillary agenesis; however, the 95% ci for those with agenesis of three molars was not significant due to the small number of individuals with the measurements (table 9). discussion to date, the literature on third molar agenesis in past assemblages is extremely sparse, and while it is at times included in the skeletal analysis (iseri & uzel, 1993; munson, 2001; öhrström et al., 2015; lieverse et al., 2014), it is not extensively discussed. only a few studies (castro, 1989; henriksson et al., 2019; nelsen et al., 2001; sengupta et al., 1999; vodanović, 2012) record assemblage-wide data on third molar agenesis as part of broader analyses of dental anomalies. in this study, 116 post-medieval skeletons from the litten cemetery in chichester were analyzed to determine the past prevalence of third molar agenesis and to test any association with reduction in molar size. 42.7% of adult and subadult skeletons with complete data (n=51/89) demonstrated m3 agenesis. when those with one or two dental quadrants missing are included (to test a larger dataset), this frequency lowered to 40.2% and 41.4%, respectively (see table 1). while this difference may be attributed to the inclusion of more data, it is also possible that the difference is the result of missing data resulting in undiagnosed agenesis. however, the difference is not statistically significant, and it is therefore acceptable to include the individuals with incomplete data as members of the assemblage. the inclusion of data groups with missing dental quadrants was also explored for subadults and adults separately, and no significant differences in the prevalence of agenesis was found between these groups. in this assemblage, 45.5% (n=18/33) of subadults have third molar agenesis. this indicates that antemortem tooth loss is less likely to have an effect on the prevalence of agenesis as subadults are exposed for less time to the pathological processes figure 2. a mandible demonstrating bilateral agenesis of the third molars from the chichester assemblage (author’s own 2017). n percent unilateral 11 28.9 bilateral 20 52.6 both 7 18.4 table 5. laterality of third molar agenesis in the chichester assemblage. bilateral agenesis occurs in over half of those with third molar agenesis. 27 dental anthropology 2021 │ volume 34│ issue 02 sex n mean sig. (2tailed)* mean difference std. error difference 95% confidence interval of the difference lower upper ulm3 buccolingual male 24 10.3717 0.005 0.82461 0.27705 0.26423 1.38499 female 17 9.5471 urm3 buccolingual male 17 10.2271 0.054 0.51984 0.26034 -0.00984 1.04951 female 18 9.7072 llm3 buccolingual male 23 8.647 0.064 0.55629 0.29138 -0.03465 1.14723 female 15 8.0907 lrm3 buccolingual male 24 8.5521 0.015 0.60708 0.23828 0.1255 1.08866 female 18 7.945 ulm3 mesiodistal male 24 6.7313 0.164 0.27596 0.19442 -0.1173 0.66921 female 17 6.4553 urm3 mesiodistal male 17 6.7335 0.028 0.49353 0.2147 0.05672 0.93034 female 18 6.24 llm3 mesiodistal male 24 8.8667 0.024 0.57042 0.24262 0.07926 1.06157 female 16 8.2963 lrm3 mesiodistal male 24 9.0913 0.017 0.64958 0.26195 0.12016 1.17901 female 18 8.4417 table 6. differences between the size of male and female third molars. male third molars are significantly larger than female third molars (in bold). agenesis n mean sig. (2tailed)* mean difference std. error difference 95% confidence interval of the difference lower upper ulm3 buccolingual present 14 9.6021 0.048 -0.52331 0.25882 -1.04179 -0.00484 absent 44 10.1255 urm3 buccolingual present 14 9.5486 0.009 -0.66248 0.24341 -1.15138 -0.17358 absent 38 10.2111 llm3 buccolingual present 9 8.0111 0.129 -0.46178 0.29957 -1.06291 0.13935 absent 45 8.4729 lrm3 buccolingual present 10 8.1040 0.461 -0.20722 0.279 -0.76591 0.35146 absent 49 8.3112 ulm3 mesiodistal present 14 6.4464 0.2 -0.25221 0.19454 -0.64191 0.1375 absent 44 6.6986 urm3 mesiodistal present 14 6.6021 0.817 -0.05207 0.22443 -0.50285 0.39872 absent 38 6.6542 llm3 mesiodistal present 9 8.3522 0.232 -0.31674 0.26231 -0.84242 0.20895 absent 48 8.6690 lrm3 mesiodistal present 10 8.8960 0.68 0.12682 0.30555 -0.48505 0.73868 absent 49 8.7692 table 7. t-test results of size comparison between those with m3 agenesis and those without m3 agenesis. *significant differences found in the ulm3 buccolingual and the urm3 buccolingual measurements (in bold). all skeletons were used in order to increase the number of individuals analyzed. separate analyses revealed similar results and therefore data groups were collated. equal variances are assumed. 28 dental anthropology 2021 │ volume 34│ issue 02 agenesis n mean sig. (2tailed) mean difference std. error difference 95% confidence interval of the difference lower upper ulm3 buccolingual present 5 8.7980 0.022 -1.15123 0.45548 -2.11680 -0.18566 absent 13 9.9492 urm3 buccolingual present 7 9.2929 0.118 -.62631 0.38043 -1.42894 0.17632 absent 12 9.9192 llm3 buccolingual present 2 7.4500 0.209 -.81200 0.61855 -2.13040 0.50640 absent 15 8.2620 lrm3 buccolingual present 3 8.0800 0.697 0.16118 0.40688 -0.69365 1.01600 absent 17 7.9188 ulm3 mesiodistal present 5 6.3560 0.779 -0.11785 0.41199 -0.99123 0.75554 absent 13 6.4738 urm3 mesiodistal present 7 6.1900 0.882 -0.05417 0.35974 -.081315 0.70481 absent 12 6.2442 llm3 mesiodistal present 2 8.3800 0.854 0.08313 0.44391 -0.85792 1.02417 absent 16 8.2969 lrm3 mesiodistal present 3 8.8800 0.438 0.41118 0.51857 -0.67831 1.50066 absent 17 8.4688 table 8. t-test results of size comparison between males with m3 agenesis and males without m3 agenesis. only the ulm3 shows significant differences in size (in bold). equal variances are assumed. measurement type n mean sig. (2tailed) mean difference 95% confidence interval of the difference lower upper llm3 mesiodistal bilateral maxillary agenesis 4 8.905 0.02 1.15 0.29535 2. 00465 agenesis of three teeth 2 7.755 0.02 1.15 -3.3154 0.7904 llm3 buccolingual bilateral maxillary agenesis 4 8.57 0.149 0.795 -0.44409 2.03409 agenesis of three teeth 2 7.775 0.149 0.795 -1.77698 2.12698 lrm3 mesiodistal bilateral maxillary agenesis 4 8.907 5 0.145 -1.2625 -3.3154 0.7904 agenesis of three teeth 1 10.17 0.145 -1.2625 -0.44409 2.03409 lrm3 buccolingual bilateral maxillary agenesis 4 8.575 0.794 0.175 -1.77698 2.12698 agenesis of three teeth 1 8.4 0.794 0.175 -0.44409 2.03409 table 9. example of analysis in size patterns between the distributions of agenesis in the dentition. the small number of individuals with measurements available for each tooth dimension in each group made it impossible to determine significant relationships between the variables. 29 dental anthropology 2021 │ volume 34│ issue 02 that stimulate antemortem tooth loss. the prevalence of 42.7% in this assemblage is significantly higher (p < .05) than those reported for british clinical samples in which data was gathered from dental radiographs. shinn (1976) found that 12.72% (n=318/2500) of patients referred to an orthodontic hospital in southampton had third molar agenesis, whereas gravely (1965) found that 25.9% (n=21/81) of patients exhibited third molar agenesis. from the bristol dental hospital, sengupta et al. (1999) found that 22% (n=22/100) of people were found to have third molar agenesis. in other groups of european ancestry prevalences of 28.2% (krekeler et al., 1974), 28.5% (trondle, 1973), 29.3% (weise & bruntsch, 1965) and 33% (elomaa & elomaa, 1973) have been reported. in european-derived north american samples, frequencies of 25.7% (keene, 1965), 22.3% (thompson et al., 1974) and 31.5% (harris & clark, 2008) have been observed. the frequency of m3 agenesis found in this study is comparable to the 44% prevalence reported in extant asian and native north american populations (carter & worthington, 2015). clinical accounts of third molar agenesis in asia appear to be higher than most european groups: 30% in a malaysian malay population (alam et al., 2014), 33% in a chinese malaysian population (alam et al., 2014), 50% in nepal (upadhyaya et al., 2012), 32.3% in japan (endo et al., 2015) and 38.4% in bangladesh (sujon et al., 1984). ren & kumar (2014) also report a prevalence of agenesis of 48% of males and 64% of females from southern india, but only 25 individuals of each sex were analyzed, and therefore the small sample size may not be representative. prevalence rates in archaeological assemblages are also extremely variable, in addition to the way in which data are collected and reported. in the present study, third molar agenesis is reported per individual, but due to preservation requirements or research questions, other studies separate data by the upper and lower dental arcade, the dental quadrant, or as an overall tooth count, making statistical comparisons with such research difficult. the late antique (n=117) and early medieval (n=245) assemblages from eastern croatia examined by vodanović (2012) produced third molar agenesis prevalences of 30.21% and 15.64% respectively, with the change in frequency attributed to population replacement in the early medieval period. radiographic assessment was not performed, and the frequency of third molar agenesis is presented separately for the upper and lower arcade, rather than for each individual. without radiographic assessment unerupted third molars may be mistaken for agenesis, creating the potential for a slightly higher prevalence than may otherwise be reported. castro (1989) found comparatively low prevalences of 7.6% in gran canaria, 10.8% in tenerife, and 9.4% in the canary islands in archaeological assemblages dating from the 1st century b.c. – 14th century a.d. in this study, a total of 1,790 maxillae and 1,920 mandibles were visually analyzed for third molar agenesis. due to the majority of mandibles having been separated from their skulls, castro (1989) calculated the frequency of agenesis separately between the upper and lower dental arches. the author divided the total number of congenitally absent third molars by the total number of third molars that would be expected if third molar agenesis was absent in each individual to determine prevalence. nelsen et al. (2001) found third molar agenesis to be prevalent in 23.5% of individuals (n=12/51) from the iron age cemetery of noen u-loke, in thailand. the authors did not use radiographic analysis. this prevalence is significantly lower, χ2 (1, n=140) = 5.2, p = 0.023, than the prevalence of 42.7% recorded in the present study. the noen uloke assemblage also has a high prevalence of lateral incisor agenesis, with 79% of individuals missing at least one lateral incisor. the authors hypothesize that endogamy and isolation likely factored in to the high prevalence of lateral incisor hypodontia. however, this does not appear to have a marked effect on the prevalence of third molar agenesis, as the modern worldwide average described by carter & worthington (2015) is 22%. in order to understand if endogamy and isolation affected the prevalence of third molar agenesis in this assemblage, analysis of other archaeological assemblages from the time period and the area with more genetic diversity would be necessary in order to confidently assess typical third molar agenesis prevalence. the methods of archaeological analysis employed by henriksson et al. (2019) in their analysis of medieval and modern norwegian assemblages align closely with the present study. the authors used both radiographic and visual analysis to determine 36 of 130 medieval skeletons had third molar agenesis. a decrease in third molar agenesis from medieval (27.7%) to modern times (17.2%) was detected. the frequency of third molar agenesis found in the present study (42.7%) is significantly higher, χ2 (1, n=219) = 5.3, p = 0.021, than the frequency recorded in the medieval norwegian 30 dental anthropology 2021 │ volume 34│ issue 02 assemblage. henriksson et al. (2019) proposes that the higher rate of third molar agenesis in the medieval assemblage compared with the modern norwegian sample may be due to the biological relationships present in the cemetery of st. olav, as opposed to the unrelated sample of modern norwegian 15 year olds. a strong genetic influence could also be present in the chichester assemblage, and may be a primary factor in the relatively high frequency of 42.7%, although further analysis is required to explore this. sengupta et al.’s (1999) analysis of victorian skeletons from the spitalfields cemetery in london represents the closest archaeological comparison to the present study, both temporally and geographically. the frequency of third molar agenesis was determined by assessing each dental quadrant as a separate specimen, and both visual and radiographic analysis were used. the prevalence of third molar agenesis presented here (42.7%) is significantly higher, χ2 (1, n=140) = 5.2, p = 0.023, than the prevalence of 23.5% recorded at spitalfields (n=12/51), and is much greater than the frequency of 14% observed in the medieval burials at st. peter’s church, barton-on-humber, also examined by sengupta et al. (1999). due to the proximity and temporal overlap with the chichester assemblage, it is likely familial genetic predispositions towards third molar agenesis were present in the chichester assemblage. in addition to a genetic component, diet could have factored in to the rates of third molar agenesis in chichester. in post-medieval britain, the diet was heavily impacted by the industrial revolution of the 17th century, with food becoming sweeter and increasingly processed (rando et al., 2014). refined flour and white bread became popular, and in 18th – early 19th century london, potatoes, bread, and tea were a dietary staple (mant, 2015). increasingly processed diets reduce dental wear on the occlusal and interproximal surfaces of teeth. as teeth wear down more space becomes available in the jaw due to the mesial drift of teeth, and without this wear, dental crowding and impaction are more likely to occur (sengupta et al., 1999). rando et al. (2014) compared the mandibular morphology of medieval and post-medieval londoners and found a decrease in the robusticity of bone associated with masticatory muscles in post-medieval skeletons. the strong association between the hardness of diet, cranio-facial development, and the resulting formation of dental anomalies has been demonstrated in the literature, and likely contributed to third molar agenesis in the chichester assemblage (corruccini et al., 1983; corruccini & lee, 1984; john et al., 2012; yamada and kimmel, 1991). however, the spitalfields assemblage (sengupta et al., 1999) was also exposed to these influences and has a much lower prevalence (23%) of third molar agenesis. therefore, dietary influences alone cannot account for the high prevalence rates found in the chichester assemblage. it is also relevant to consider the how the biocultural environment, the relationship between biological and cultural elements, may have impacted growth in post-medieval chichester. despite the resistance of tooth formation to growth disruptions (hillson, 2005), delayed dental eruption is often reported in individuals with systemic disease, in the absence of essential nutrients, or in individuals living in a low socioeconomic setting (cardoso, 2007; suri et al., 2004). delayed formation and eruption has also been correlated with increased frequency of third molar agenesis, and reduced morphological complexity in first and second molars (anderson and popovich, 1981). research has shown that the pre-natal environment and the quality of breastfeeding during tooth development also affect the size of the third molars (garn et al., 1980; grüneberg, 1951; grüneberg, 1963; lumey and stein, 1985). in chichester in the early 17th century and again in 1665, the plague was present, and smallpox peaked in 1722, 1740, 1759 and 1775 (morgan, 1992). in the 19th century, “the health of chichester often lagged behind the rest of the country” (morgan, 1991:23), with epidemics linked to water and sewage, such as cholera and typhoid fever, occurring at regular interval. statistics from 1871-1880 put chichester amongst the highest number of cases of consumption and typhoid fever in the country, and historical records detail poor sanitation and a lack of the necessary infrastructure for clean water supply and sewage drainage (morgan, 1992). such adverse conditions would certainly have disrupted growth, and may have also had an impact on the development of third molars. size reduction and agenesis third molars highly reduced in size, both in mesiodistal and buccolingual dimensions, and/or simplified in morphology, are often referred to as vestigial molars (nanda, 1954), a term that implies an evolutionary trend towards dental reduction. these third molars are easily recognized upon visual assessment. in nanda’s (1954) analysis of vestigial third molars, all individuals with diminution also had third molar agenesis in other dental quadrants. size reduction has also been demonstrated in 31 dental anthropology 2021 │ volume 34│ issue 02 dentitions with agenesis of other tooth types (baum & cohen, 1971). grüneburg (1951) proposed that agenesis is the most severe expression of a size continuum, in which the tooth germ falls below a critical threshold and formation ceases. from this evidence it might be expected that individuals in the chichester assemblage who demonstrate third molar agenesis would have other third molars reduced in size and would be smaller upon comparison with those that do not have third molar agenesis. in this assemblage, all individuals demonstrating vestigial third molars (n=7) (figure 3) had third molar agenesis, except for one skeleton that was missing data on the urm3. it is likely the number of vestigial third molars in this assemblage would have been higher had post-mortem loss not been a factor, and if third molars in alveolar tooth crypts had been measured radiographically. buccolingual measurements of the maxillary third molars in individuals with agenesis were significantly smaller (p < 0.05) than those without agenesis in this study (table 7). maxillary third molars are more frequently reported congenitally absent than mandibular third molars in the literature (carter & worthington, 2015). given that the buccolingual dimensions of maxillary third molars in this assemblage were smaller in those with agenesis, it is possible to infer maxillary molars are more vulnerable not only to agenesis, but to diminution as well; however, mandibular agenesis was found to be slightly more common in this assemblage (54% vs 46%, table 4), though this difference was not statistically significant, χ2 (1, n=166) =1.18, p = 0.278. baum & cohen (1971) collected buccolingual and mesiodistal measurements of all teeth, except third molars, from a clinical sample of europeanderived ancestry in the northeastern united states. they analyzed size reduction in the presence of dental agenesis in tooth types other than the third molar. in contrast to the present study, the authors found that mesiodistal dimensions demonstrated a statistically significant association with size reduction and agenesis in 70% of tooth types, excluding third molars. buccolingual dimensions were, however, only reliable indicators of the association between size reduction and agenesis in measurements of the canines. garn et al. (1968) investigated the relationship between buccolingual and mesiodistal dimensions. while the two are correlated, the results reveal more autonomy than commonality governing morphological expression, although the further distal in the dental arcade the tooth, the higher the correlation between the two dimensions. therefore, it might be expected that both the mesiodistal and buccolingual dimensions of third molars would demonstrate an association with size reduction and agenesis. the fact mesiodistal measurements did not show a statistically significant association between size reduction and agenesis in this study may be due the small number of individuals in this cohort, the highly variable morphology of third molars, or it could be an indication that the relationship between buccolingual and mesiodistal dimensions is both population dependent and complex. another factor complicating results is the significant differences (p < 0.05) in size between the third molars of males and females (see table 6). to explore this further, an analysis of the relationship between size and agenesis was conducted separately. removing indeterminate sex from the pool of measurements eliminated 29% of the assemblage. males (n=46) continued to present significantly smaller third molars in the presence of third molar agenesis compared to those without agenesis in the buccolingual dimension of the upper left third molar. the smaller female sample size (n=36) made testing the correlation between agenesis with smaller tooth size more difficult. the final question of analysis in this study focused on detecting patterns in size reduction amongst those with third molar agenesis. khalaf (2016) analyzed the relationship between size reduction and agenesis in all tooth types in individufigure 3. left portion of a mandible demonstrating a third molar reduced in size and morphology (author’s own 2017). the remaining third molars are congenitally absent. 32 dental anthropology 2021 │ volume 34│ issue 02 als with mild (≤2 teeth congenitally missing), moderate (3-5 teeth congenitally missing) and severe (≥6 teeth congenitally missing) hypodontia. they found that size reduction in the remaining teeth increased with the severity of hypodontia. with this research in mind and grewal’s (1951) evidence of third molar diminution in mice, it was hypothesized that individuals in the chichester assemblage with three third molars congenitally absent might have a smaller remaining third molar than those with less third molars congenitally absent. in addition to relationships in size within third molar agenesis, any differences that existed between certain groups of third molar agenesis and those without agenesis, for example those with three congenitally absent third molars and those without third molar agenesis, were tested to determine if size differences in third molars could be found between these groups. unfortunately, this reduced the number of individuals in each measurement category and it was not possible to reach statistical significance (see table 9). size patterns within third molar agenesis have yet to be explored in modern or archaeological data, and therefore further testing is required. conclusions rates of third molar agenesis recorded in modern clinical data are often interpreted as a secular trend in which the third molar, now deemed redundant due to decreased dental wear, low masticatory stress and soft diets, will eventually cease development and potentially disappear from the human dentition. although there is an established genetic component, the etiology is far from clear. research on archaeological assemblages is vital in order to better understand the trajectory and origin of this phenomenon, and this study provides a valuable contribution to the relatively little that is known about third molar agenesis prevalence in the past. in post-medieval chichester, third molar agenesis occurred in 42.7% of individuals. this result is higher than any reported for a clinical british sample, and it is also significantly higher than the prevalence reported from the victorian spitalfields assemblage (sengupta et al., 1999), indicating that an inheritance pattern may be present amongst the skeletons from the post-medieval assemblage of the litten cemetery in chichester. while reduced dental wear and masticatory stimulation may contribute to the frequency of agenesis in this assemblage, a strong genetic influence combined with the adverse community health conditions may prove to be important etiological components of third molar agenesis and avenues for future research. significant differences in the size of third molars between those with third molar agenesis and those without were found, although only two of the eight measurements analyzed were found to be significant. if third molars are indeed vestigial, more studies with larger sample sizes will be needed to further test any temporal trend. this includes the examination of archaeological as well as clinical samples. acknowledgements i thank dr. carolyn rando and dr. simon hillson, university college of london, institute of archaeology, for their teaching and guidance during my master’s thesis, from which this project derives. i would also like to offer my gratitude to four anonymous reviewers for their work on earlier drafts, and to dr. anita sengupta, university of manchester, division of dentistry, for her assistance in my data collection. finally, i would like to sincerely thank emma phillips and dannielle croucher for their much appreciated participation in my io error study. references alam, m.k., muhammad, a.h., muhammad, a.k., shaifulizan, a.r., ramizu, s., & hassan, a. 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(1985). famine and birthweight in the second generation: maternal transmission of an environmental experience. in: abstract iv congress of auxology, montreal. philadelphia: taylor & francis. mant, m., & roberts, c. (2015). diet and dental caries in post-medieval london. international journal of historical archaeology, 19(1), 188–207. morgan, r. (1992). chichester: a documentary history. 1st ed, chichester, sussex: phillmore & co ltd. munson, c. (2001). residential mortuary practices and skeletal biology at the late mississippian hovey lake site, posey county, indiana. midcontinental journal of archaeology, mcja, 26(1), 1-52. nanda, r.s. (1954). agenesis of the third molar in man. american journal of orthodontics, 40(9), 698 –706. nelsen, k., tayles, n., & domett, k. (2001). missing lateral incisors in iron age south-east asians as possible indicators of dental agenesis. archives of oral biology, 46, 963-971. öhrström, l., seiler, r., böni, t., aali, a., stöllner, t., & rühli, f. (2015). radiological findings in an ancient iranian salt mummy (chehrabad ca. 410-350 bc). skeletal radiology, 44(6), 811–821. phenice, t.w. (1969). a newly developed visual method of sexing the os pubis. american journal of physical anthropology, 30(2), 297–301. raloti, s., mori, r., makwana, s., patel, v., menat, a. & chaudhari, n. (2013). study of a relationship between agenesis and impacted third molar (wisdom) teeth. international journal of research medicine, 2(1), 38-41. rando, c. (2016). the human remains collections at the ucl institute of archaeology: recent acquisitions from eastgate square, chichester, sussex. archaeology international, 19(3), 79–83. rando, c., hillson, s., & antoine, d. (2014). changes in mandibular dimensions during the mediaeval to post-mediaeval transition in london: a possible response to decreased masticatory load. archives of oral biology, 59(1), 73–81. ren, cg, kumar, b.s. (2014). prevalence of eruption of third molar tooth among south indians and malaysians. journal of academic dental education, 1(1), 32–35. sengupta, a., whittaker, d.k., barber, g., rogers, j., & musgrave, j.h. (1999). the effects of dental wear on third molar eruption and on the curve of spee in human archaeological dentitions. archives of oral biology, 44(11), 925–934. shinn, d.l. (1976). congenitally missing third molars in a british population. journal of dentistry, 4(1), 42–44. sujon, m.k.k., alam, m.k.a. & rahman, s.a. (2016). prevalence of third molar agenesis: associated dental anomalies in non-syndromic 5923 patients. plos one, 11(8), 1-9. suri, l., gagari, e., & vastardis, h. (2004). delayed tooth eruption: pathogenesis, diagnosis, and treatment. a literature review. american journal of orthodontics & dentofacial orthopedics, 126(4), 432–445. thompson, g.w., popovich, f. & anderson, d.l. (1974). third molar agenesis in the burlington growth centre in toronto. community dentistry and oral epidemiology, 2(4), 187–192. tröndle, d. (1973). röntgenologische untersuchungen zum nachweis der nichtanlage und dystopie der weisheitszähne. med. diss., freiburg. ubelaker, d.h.m.n. (1989). human skeletal remains: excavation, analysis, interpretation. 2nd ed., washington: taraxacum. upadhyaya, c., adhikari, b.r., kafle, d., & humagain, m. (2012). agenesis of third molars 35 dental anthropology 2021 │ volume 34│ issue 02 in orthodontic patients attending dhulikhel hospital. orthodontic journal nepal, 2(1), 32–35. vodanović, m., galić, i., strujićc, m., peroš, k., šlause, m., & brkića, h. (2012) orthodontic anomalies and malocclusions in late antique and early mediaeval period in croatia. archives of oral biology, 57, 401-412. weise, w., & bruntsch, e. (1965). rőntgenologische untersuchungen zum nachweis und zur entwicklung des weisheitszahnes. zahnärztl rdsch, 74, 245–249. yamada, k., & kimmel, d.b. (1991). the effect of dietary consistency on bone mass and turnover in the growing rat mandible. archives of oral biology, 36(2), 129–138. harris 2010.5 61 tooth-formation standards for the primary teeth are quite scarce, largely because these teeth begin developing in utero where analysis is complicated and because dental researchers have avoided dealing with very young children, especially where irradiation is involved. a singular exception, due in large part to the tireless efforts of arthur b. lewis, is the analysis of primary tooth mineralization in children between birth and about 16 years of age (moorrees et al., 1963a). while data from the earliest-forming teeth, the incisors, are unavailable, moorrees, fanning and hunt (1963a) reported on the formative stages and the later exfoliation of three primary tooth types, specifically the canine, first and second molars in the mandible. this report, in the american journal of physical anthropology, accompanies these authors’ better-known study of the permanent dentition (moorrees et al., 1963b). their study of the primary teeth has been useful in several studies, but the authors chose to present their data in graphical form only, which has been an impediment to using the data statistically. in hopes that these tabulated data will be more useful to others, i have converted the graphical data into more applicable tables of medians and standard deviations. to my knowledge, these are the only published data on the tooth mineralization of primary teeth that span the relevant postnatal age interval (neonates up to school age). comparable radiographic data were collected in the bolton-brush study (cleveland, ohio) as reviewed by behrents (1985) and in the child research council (denver, colorado) as reviewed by mccammon (1970), but these radiographs do not seem to have been analyzed to develop tooth-formation data. demirjian and colleagues (e.g., demirjian et al., 1982) also collected the needed data from their longitudinal study of frenchcanadian children in montreal, though these data do not technical note: primary tooth mineralization and exfoliation ages calculated from the moorrees-fanninghunt study edward f. harris department of orthodontics, university of tennessee, memphis abstract staging of the formation of teeth and shedding of the primary teeth are particularly useful for age estimation of archaeological and forensic specimens, as well as for gauging whether a child’s tempo of maturation is progressing within normal limits. staging can be done using radiographs or with direct inspection of dental remains. standards for the primary dentition are scarce, but obviously needed for young children. this note provides tables, by sex, of the normative ages of the mineralization of three mandibular tooth types (c, m1, m2) as well as of root resorption and times of shedding of these tooth types. the data are transformed from charts developed by moorrees, fanning and hunt (1963 am j phys anthropol 21:99-108). conversion to numeric form is intended to aid in using these data for statistical comparisons. dental anthropology 2010;23(2):61-65. stage code tooth mineralization coalescence of cusp c co cusp outline complete c oc crown ½ complete cr ½ crown ¾ complete cr ¾ crown complete cr c initial root formation r i initial cleft formation cl i root length ¼ r ¼ root length ½ r ½ root length ¾ r ¾ root length complete r c apex ½ closed a ½ apex closure complete a c tooth exfoliation one-fourth root reorption res ¼ one-half root resorption res ½ three-fourths root resorption res ¾ table 1. the stages of tooth formation and resorption developed by moorrees and coworkers seem to be published. in contrast, there are several studies that report on the eruption ages of the primary teeth (e.g., falkner, 1957; infante, 1974; delgado et al., 1975; tanguay et al. 1986), based either on direct intraoral examinations or on serial dental casts (moorrees, 1959). correspondence: edward f. harris, department of orthodontics, university of tennessee, memphis 38163 e-mail: eharris@uthsc.edu 62 formation girls boys stage median sd median sd primary canine c co • • • • c oc 0.1 0.09 0.2 0.09 cr ½ 0.3 0.10 0.3 0.10 cr ¾ 0.5 0.12 0.5 0.12 cr c 0.7 0.14 0.7 0.14 r i 0.9 0.15 0.8 0.16 r ¼ 1.1 0.17 1.0 0.17 r ½ 1.3 0.20 1.3 0.20 r ¾ 1.8 0.25 1.9 0.25 r c 2.1 0.27 2.0 0.26 a ½ 2.5 0.32 2.5 0.32 a c 3.0 0.36 3.1 0.37 primary first molar c co • • • • c oc • • • • cr ½ 0.1 0.09 0.2 0.09 cr ¾ 0.2 0.10 0.3 0.09 cr c 0.3 0.11 0.5 0.12 r i 0.6 0.12 0.6 0.13 cleft 0.6 0.12 0.7 0.14 r ¼ 0.6 0.14 0.8 0.15 r ½ 0.9 0.16 0.9 0.16 r ¾ 1.1 0.18 1.2 0.19 r c 1.3 0.19 1.3 0.20 a ½ 1.5 0.22 1.7 0.24 a c 1.8 0.25 2.0 0.26 primary second molar c co • • • • c oc • • 0.2 0.09 cr ½ 0.2 0.10 0.3 0.10 cr ¾ 0.5 0.12 0.5 0.12 cr c 0.7 0.14 0.7 0.14 r i 0.9 0.16 0.9 0.16 cleft 1.0 0.16 1.0 0.16 r ¼ 1.3 0.20 1.3 0.21 r ½ 1.6 0.22 1.9 0.23 r¾ 1.9 0.26 2.0 0.21 r c 2.0 0.27 2.0 0.27 a ½ 2.4 0.30 2.4 0.31 a c 2.8 0.35 3.1 0.37 1statistics are the median chronologic age and its standard deviation (sd). these norms were developed from serial x-rays taken on 136 boys and 110 girls from among those enrolled in the fels longitudinal study, yellow springs, ohio. table 2. median ages (years), by sex, for stages of mandibular primary tooth formation1 the data as stated in their article, moorrees et al. (1963b) collected data from the fels longitudinal study located in yellow springs, ohio (roche, 1992). this is one of the premiere longitudinal growth studies in the world, following children from birth into biological adulthood. the fels study had its inception in 1929, and from then until the early 1960s (when moorrees and coworkers collected their data), between 500 and 600 children had been enrolled (roche, 1992). lateral and oblique headfilms (radiographs) were taken at 3-month intervals during the first year of life and at 6-month intervals thereafter (moorrees et al., 1963a). these planar radiographs were an efficient means of visualizing all of the teeth with one or two films; this was in the era before panoramic films were available (graber, 1966). experience suggests that the researchers focused on the mandibular teeth because the tooth images are clearer in this arch, whereas the maxillary images are overlain with complex bony shadows. strong intercorrelations between stages of homologous teeth in the two arches (moorrees and reed, 1954; kent et al., 1978) can be used as an argument for restricting attention to just one arch. moorrees et al. state that their standards are based on the serial radiographic records of 136 boys and 110 girls. moorrees and coworkers thought the charts that they developed were most useful for clinical application. for a single case, this might be true. i used photoshop cs3 to measure high-quality scans of he charts and then transformed these measurements back to decimal years. (comparable tabulations of permanent tooth formation e.f. harris fig. 1. sketches of the 3 stages of primary tooth root resorption used bymoorrees, fanning and hunt (1963a). 4 1 1 2 3 4 resorption resorption resorption singlerooted multirooted 63 girls boys stage median sd median sd canine res ¼ 4.93 0.45 6.08 0.55 res ½ 7.26 0.65 8.41 0.74 res ¾ 8.73 0.76 9.79 0.84 exfoliation 9.53 0.83 10.64 0.92 first molar, mesial root res ¼ 4.90 0.45 5.45 0.49 res ½ 7.25 0.64 7.58 0.68 res ¾ 8.85 0.77 9.41 0.82 exfoliation 10.12 0.87 10.79 0.93 first molar, distal root res ¼ 5.17 0.48 6.39 0.58 res ½ 7.68 0.66 8.35 0.73 res ¾ 9.75 0.81 10.01 0.87 exfoliation 10.12 0.87 10.79 0.93 second molar, mesial root res ¼ 6.09 0.55 6.65 0.59 res ½ 8.31 0.73 8.61 0.74 res ¾ 10.02 0.87 10.42 0.90 exfoliation 11.13 0.96 11.67 1.00 second molar, distal root res ¼ 6.95 0.62 7.45 0.65 res ½ 8.61 0.76 9.51 0.82 res ¾ 9.95 0.87 11.08 0.95 exfoliation 11.12 0.96 11.64 1.00 table 3. median ages (years), by sex, for stages of mandibular primary tooth resorption and exfoliation primary tooth resorption standards [moorrees et al., 1963b] are available in harris and buck, 2002.) the researchers as an aside, it is interesting to note the serendipity (synergism) of moorrees, fanning, and hunt’s collaboration. moorrees (b. 1916 – d. 2003) certainly had a knowledgeable interest in development of the dentition (see, e.g., moorrees, 1959), and he was in a position at the forsyth dental infirmary (harvard school of dental medicine) to coordinate the study (moorrees, 1993; peck and will, 2004). elizabeth fanning (b. 1918 – d. 2007) was trained in australia as a dentist (townsend, 2007), and she brought her expertise in scoring tooth-mineralization stages. beginning with her thesis (fanning, 1960), fanning developed elaborate grading systems; these have generally been eschewed by subsequent workers as too detailed to allow high intraobserver reliability in their hands. however, if mastered, these stages of short duration provide fine-grained analysis. ed hunt (b. 1922 – d. 1991) a physical anthropologist at harvard university had research interests in growth and development, but he also had a strong background in quantitative methods (baker, 1992), and he was the team member who actually calculated the probit analyses (e.g., finney, 1971) that yielded the median ages at each stage of tooth formation and of exfoliation. the collaboration involved moorrees overseeing the study, fanning scoring the tooth stages from the films, and hunt calculating the statistics. the unsung hero in this scenario is arthur b. (“buzz”) lewis, a dental specialist in orthodontics, who maintained a private practice as well as an appointment on the orthodontic faculty at ohio state university throughout his professional life. lewis also was a research associate at the fels research institute for a full half-century (mayerson, 1996), and most dental anthropologists will recall his numerous publications with stanley garn. lewis is the man responsible for taking the dental radiographs of the participants at fels, with x-rays taken every 3 months for the first year, then at 6-month intervals after that. without the radiographs of these infants—a considerable undertaking in itself—there would have been no data to collect. primary tooth formation the original charts record two sequential processes, one is the formation of these three primary teeth (c, m1, m2) that begin mineralization as early as the second trimester (lunt and law, 1974) and continue till about 3 years of age. the second process, some years later, occurs during the “second transition” of dental development (van der linden and duterloo, 1976), when these primary teeth are exfoliated and replaced by the permanent canine and premolars in each quadrant. shedding of these primary teeth occurs between 9 and 11 years of age, with subsequent emergence of the successors. moorrees et al. used the same 12 stages of tooth mineralization as they used elsewhere to score the permanent teeth (moorrees et al. 1963b). one additional stage (cleft formation) was used to note the interradicular area of multi-rooted teeth. the interval from about 2 ½ years (when all 20 primary teeth have emerged into occlusion) to about 6 years of age (when the permanent first molar emerges) is viewed as the interval of the intact primary dentition. these data (tables 1, 2) show that these three teeth begin their resorptive processes by about 5 years of age (somewhat later in boys) when the canines and first molars initiate root resorption. this is, of course, some years before exfoliation. histologically, osteoclasts are congregated and mature ahead of the successor’s dental sac (wise et al., 1999, 2002, 2008), and these multinucleated cells remove the bone and deciduous tooth roots ahead of the replacement tooth. timely resorption of the primary tooth’s root is necessary for normal eruption of the permanent tooth. the biochemical signaling for lysis is from the dental follicle of the permanent successor. this is why, when the successor is congenitally absent, exfoliation of the primary tooth is delayed, often for many years though roots still tend to 64 e.f. harris resorb albeit slowly (e.g., haselden et al., 2001; nordquist et al. 2005; bjerklin et al., 2008). primary tooth mineralization progresses more rapidly than in the permanent successors, and this is reflected in smaller overall sizes, thinner tissue components, and lower enamel and dentin densities (e.g., mcdonald, 1978; wilson 1989; hunter, 2000). the moorrees charts (table 2) show that about half of the crowns are mineralized in utero, so their staging is missed even when radiographs are taken at birth. results show that girls progress faster than boys. differences are small and not significant statistically (based on univariate comparisons of 95% confidence limits), but younger median ages in girls are widespread across the data. parenthetically, this raises the interesting question of ethnic and environmental influences on rates of development. assessed multivariately, tanguay and coworkers (1986) found earlier tooth primary emergence for boys, though other studies have reported different results, generally no discernible sex difference (demirjian, 1978). the first molar is particularly fast-forming. it completes crown formation (amelogenesis) by about 4 months after birth and roots are apexified by 2 years of age. the other two tooth types form more slowly, with average crown completion at about 0.7 years (~ 8 months), and with root completion (a c ) by 3 years of age. tooth exfoliation shedding of these teeth occurs between about 10 and 11 years of age (table 3), which is consistent with conventional mnemonics that these primary teeth are shed and their successors emerge around the 2-year interval of the second transition (van der linden and duterloo, 1976) interestingly, resorption of the roots of these primary teeth begins several years earlier. resorption is noted on the canine and first molar by about 5 years of age. three stages of root resorption were scored, along with exfoliation as the ultimate event (fig. 1). initial evidence (r¼) of resorption occurs late, between 6 and 7 years of age, for the second molar. durations of the exfoliation process can be gauged by comparing the earliest evidence of root loss (r¼) to when the tooth actually is lost. the process takes 4 to 5 years on the average, but somewhat less for the canine (~ 4 years) than the two molars. fanning’s attention to detail allows us to see that the mesial root of the molars resorb faster than the distal root. this may be due to the mesial crown tip of molars (e.g., dempster et al. 1963), so the mesial root is under greater compression when the molar is under pressure. this cause is speculative, but precocity of the mesial root attaining resorption stages is consistent across the data. table 3 also discloses the strong trend for girls to shed these teeth ahead of boys. normal shedding of a primary tooth involves lysis of the roots and of the bone ahead of the succeeding tooth (wise and king, 2008), so the female precedence that has long been known for permanent tooth emergence (hurme 1949) is part and parcel of this process. overview this note presents tabled statistics for three primary mandibular tooth types (c, m1, m2) with regard to their mineralization (table 2) and their subsequent resorption (table 3). tables are transformed from the graphs produced fig. 2. plots of the median ages of primary tooth resorption. girls tend to be developmentally ahead of boys, though the patterns of change and the sequencing are similar in the two sexes. mesial root of m1 tends to be the first of these three teeth to exhibit resorption, while the distal root of m2 is the last to resorb. sequencing coincides with the high prevalence of cases where m1 exfoliates earlier than m2 (and the first premolar emerges earlier than the second). 65primary tooth resorption by moorrees et al. (1963a) with the intent of making the data more usable for statistical applications. literature cited baker pt. 1992. obituary: edward eyre hunt, jr. (19221991). am j phys anthropol 89:123-125. bjerklin k, al-najjar m, kårestedt h, andrén a. 2008. agenesis of mandibular second premolars with retained primary molars: a longitudinal radiographic study of 99 subjects from 12 years of age to adulthood. eur j orthod 30:254-261. behrents rg. 1985. in search of truth for the greater good of man: a chronological account of the bolton-brush growth studies. cleveland: bolton study press of case western reserve university. delgado h, habicht jp, yarbrough c, lechtig a, martorell, r, malina r, klein r. 1975. nutritional status and the timing of the deciduous tooth eruption. am j clin nutr 28:216-224. demirjian a. 1978. the dentition. in: human growth, vol 2. postnatal growth. falkner f, tanner jm, eds. new york: plenum publishers, p 413-444. demirjian a, la palme l, thibault hw. 1982. la croissance staturo-ponde’rale des enfants canadiens-francais de la naissance a 36 mois. union med can 112:153-163. dempster wt, adams wj, duddies ra. 1963. arrangement in the jaws of the roots of the teeth. j am dent assoc 67:779-797. falkner f. 1957. deciduous tooth eruption. arch dis child 32;386-391. fanning ea. 1960. a longitudinal study of tooth formation and root resorption. d.d.s. thesis, university of new zealand. finney dj. 1971. probit analysis, 3rd ed. cambridge, great britain: cambridge university press. graber tm. 1966. panoramic radiography. angle orthod 36:293-311. harris ef, buck a. 2002. tooth mineralization: a technical note on the moorrees-fanning-hunt standards. dental anthropology 16:15-20. haselden k, hobkirk ja, goodman jr, jones sp, hemmings kw. 2001. root resorption in retained deciduous canine and molar teeth without permanent successors in patients with severe hypodontia. int j paediatr dent 11:171-178. hunter ml. 2000. erosion of deciduous and permanent dental hard tissue in the oral environment. j dent 28:257-263. hurme vo. 1949. ranges of normalcy in the eruption of permanent teeth. j dent child 16:11-15. infante pf. 1974. sex differences in the chronology of deciduous tooth emergence in white and black children. j dent res 53:418. kent rl jr, reed rb, moorrees cf. 1978. associations in emergence age among permanent teeth. am j phys anthropol 48:131-142. lunt rc, law db. 1974. a review of the chronology of calcification of deciduous teeth. j am dent assoc 89:599-606. mayerson m. 1996. in memoriam: arthur b. lewis (19091996). am j orthod dentofacial orthop 110:329. mccammon rw. 1970. human growth and development. springfield: charles c thomas, publisher. mcdonald re. 1978. dentistry for the child and adolescent, 3rd ed. st louis. cv mosby, p 39-44. moorrees cfa. 1959. the dentition of the growing child: a longitudinal study of dental development between 3 and 18 years of age. cambridge: harvard university press. moorrees cf. 1993. reflections on an academic career in teaching and research. am j orthod dentofacial orthop 104:516-522. moorrees cfa, fanning ea, hunt ee jr. 1963a. formation and resorption of three deciduous teeth in children. am j phys anthropol 21:99-108. moorrees cfa, fanning ea, hunt ee jr. 1963b. age variation of formation stages for ten permanent teeth. j dent res 42:1490-1502. moorrees cf, reed rb. 1954. biometrics of crowding and spacing of the teeth in the mandible. am j phys anthropol 12:77-88. nordquist i, lennartsson b, paulander j. 2005. primary teeth in adults—a pilot study. swed dent j 29:27-34. peck s, will la. 2004. in memoriam: coenraad f.a. moorrees, 1916-2003. am j orthod dentofacial orthop 125:396-398. roche af. 1992. growth, maturation and body composition: the fels longitudinal study, 1929-1991. cambridge, great britain: cambridge university press. tanguay r, buschang ph, demirjian a. 1986. sexual dimorphism in the emergence of deciduous teeth: its relationship with growth components in height. am j phys anthropol 69:511-515. townsend g. 2007. comments. dental anthropology 20:25-27. van der linden fpgm, and duterloo hs. 1976. development of the human dentition. hagerstown: harper and rowe publishers. wilson pr. 1989. mineralization differences between human deciduous and permanent enamel measured by quantitative microradiography. arch oral biol 34:85-88. wise ge, frazier-bowers s, d’souza rn. 2002. cellular, molecular, and genetic determinants of tooth eruption. crit rev oral biol med 13:323-334. wise ge, huang h, que bg. 1999. gene expression of potential tooth eruption molecules in the dental follicle of the mouse. eur j oral sci 107:482-486. wise ge, king gj. 2008. mechanisms of tooth eruption and orthodontic tooth movement. j dent res 87:414-434. edgcomb et al. 2011.2 11 root resorption is the most frequent unwanted side-effect of orthodontic treatment discussed with new patients, and occurs in all orthodontic patients to various degrees (weiland, 2006). the risk of root resorption during treatment has been found to be related to a number of factors, including dental anomalies, syndromes, variations in dental anatomy, sex, mechanics of orthodontic treatment, and disturbances during development, among others. developmentally short dental roots have been observed to experience a higher incidence of root resorption during orthodontic treatment. thongudomporn and freer (1998) found that teeth with one or more dental anomalies, such as invaginations, pipette-shaped roots, or short and blunted roots undergo a significant amount of root resorption during orthodontic treatment as opposed to teeth without these anomalies. lind (1972) was the first to suggest the connection between developmentally short dental roots and root resorption. he defined short root anomaly as involvement of bilateral maxillary incisors and less commonly canines and premolars. lind measured the crown-to-root ratios of short-rooted and normal teeth on intraoral radiographs and found that the control group had an average of 5.5 mm longer maxillary incisor roots than the experimental group. developmentally short roots have been found in 1.2-10.0% of pretreatment orthodontic patients (uslu et al., 2009). these teeth have an unfavorable crown-to-root ratios as compared to teeth with normal root length (höltta et al., 2004). the ratio of crown-to-root length in these shortened teeth is at least 1.0:1.6 (desai et al., 2006). developmentally short roots have been found to be associated with syndromes such as dentin dysplasia, scleroderma, steven’s-johnson syndrome, laurence-moon-bardet-biedl syndrome, thalassemia, down syndrome, aarskog syndrome, dwarfism, and rothmund-thomson syndrome (desai et al., 2006). they may also occur simultaneously with other dental anomalies, such as tooth agenesis, dens invaginatus, supernumerary teeth, generalized microdontia, obliterated pulp chambers, increased tooth mobility, and spontaneous exfoliation (apajalahti et al., 1999). short dental roots may develop from three mechanisms: disturbances during development, resorption of previously well-formed roots, or genetics. disturbances during root development can result from radiation or chemotherapy exposure during childhood, or systemic illness such as hypoparathyroidism. resorption of originally well-formed roots may follow trauma or occur during orthodontic treatment. short roots may have a genetic origin, such as short root anomaly (höltta et al., 2004). teeth with short roots pose difficulties in orthodontic and prosthodontic treatment planning as a result of their unfavorable crown-to-root ratio. anchorage methods and occlusal loading need to be considered carefully in teeth with short roots (höltta et al., 2004). the purpose of the current study is to prevalence of short dental roots in four ethnic groups in an orthodontic population kathryn edgcomb1*, ellen begole1, carla evans1, bradford johnson2, xianghong luan3 1department of orthodontics, 2department of endodontics, and 3department of oral biology, college of dentistry, university of illinois at chicago abstract the purpose of the current study was to investigate if a significant relationship exists between ethnicity, sex, and short dental roots. the hypotheses are: 1. hispanics have a higher prevalence of short dental roots than caucasians, african americans, and asians; and 2. females have a higher prevalence of short dental roots than males. the experimental groups consisted of 30 caucasians, 30 hispanics, 30 african americans, and 26 asian subjects who presented to university of illinois department of orthodontics for treatment. actual root length (mm) and relative root length were measured on periapical radiographs, for the maxillary and mandibular central and lateral incisors, and second premolars. the results showed that asians had the shortest dental root lengths for all teeth measured, except the maxillary second premolar. significant differences in relative root length values between the ethnic groups were found for the maxillary central incisor and second premolar. females had shorter roots than their male counterparts within each ethnic group. dental anthropology 2011;24 (1):11-15. *correspondence to: kathryn edgcomb, department of orthodontics, university of illinois at chicago, chicago, il 60612 usa. e-mail: kathryn.edgcomb@gmail.com 12 investigate the relationship between ethnicity and the prevalence of developmentally short dental roots. two hypotheses were tested in this study, namely 1)hispanics have a statistically significant higher prevalence of developmentally short dental roots than caucasians, african americans, and asians, and 2) females have a higher prevalence of short dental roots than males. if one or more ethnic groups show an increased prevalence of short roots, it may be assumed that they would be at increased risk for root resorption during orthodontic treatment as stated in previous research. this information would be helpful to orthodontists in treatment planning mechanics for their patients. materials and methods the experimental groups consisted of caucasians, african americans, hispanics, and asians with 30 subjects in each ethnic group except the asian group which had 26 subjects due to a lack of cases that met the inclusion criteria for this study. the subjects were at least 14 years of age and both male and female. the subjects’ dental records came from the university of illinois college of dentistry orthodontic clinic patient pool. subjects satisfied all inclusion criteria, including no history of dental trauma, orthodontics, endodontics, or oral surgery to the teeth being measured. the teeth could not have large caries or restorations of half or more of the crown, significant attrition, significant dilaceration of the root, or be rotated such that their facial and palatal surface were not parallel to the x-ray film. subjects with craniofacial malformations, such as cleft lip and palate, were excluded. all permanent teeth were fully erupted, except third molars, and all apices of the teeth were closed. all subjects must have had their pretreatment periapical radiographs taken at the university of illinois college of dentistry radiology clinic between the dates of january 1, 2000, and april 14, 2010. radiographic measurement technique maxillary and mandibular central and lateral incisors, and second premolar root lengths were measured from the apex to the cervical constriction of the anatomic crown on periapical radiographs. these teeth were chosen because they were single-rooted teeth and their root structures were more clearly identified on radiographs than multi-rooted teeth. as shown in figure 1, the xy line represents the anatomic cementoenamel junction and was found on the radiographs by connecting the mesial and distal cervical constrictions with a line. point m is defined as the intersection of the xy line and a straight line connecting the root apex (r) and the midpoint of the incisal edge (i). the length of the root was measured in millimeters from point m to r. the relative root length was measured by dividing the root length (mr) by the crown length (im) and expressed as a ratio. the statistical analysis was done using spss version 16 (spss, chicago il). the data measurements gathered were first tested for normality. two-way analysis of variance tests were done using ethnic group and sex as factors for all teeth measured. p-values of less than or equal to 0.05 were considered statistically significant (two tail). if the overall anova showed significance, scheffé tests were used to isolate pairwise differences among the means. results the descriptive statistics for maxillary central incisor root length and relative root length are shown in table 1. african american males had the longest mean root length (17.12 mm) and asian females had the shortest mean root length (13.73 mm), and this difference between the groups (f = 3.30, p = 0.02) and sexes (f = 22.0, p = 0.000) was statistically significant. caucasian males had the highest relative root length values (1.66) and asian females had the smallest (1.40), but this difference was not statistically significant (f = 2.87, p = 0.09). the descriptive statistics for maxillary lateral incisor root length can be seen in table 2. a significant difference between sexes was found in the two-way anova, with males having longer mean root length than females by 0.99 mm (f = 8.34, p = 0.005). african american males had the longest mean root length (16.63 mm) and asian females had the shortest mean root length (14.67 mm). the descriptive statistics for the maxillary second edgcomb et al. fig. 1. reference lines used to measure root length (m to r) and relative root length (m to r divided by i to m). x y r i m 13 premolar relative root length are shown in table 3. african american males had the highest relative root length value (1.70) and caucasian males had the lowest (1.61), but this difference was not statistically significant between groups (f = 0.58, p = 0.63) or sexes (f = 0.02, p = 0.88). caucasian females had relative root length values 0.6 higher than caucasian males. hispanic males had a relative root length value 0.3 higher than hispanic females. african american males had a relative root length value 0.8 higher than african american females. finally, asian females had a relative root length value 0.3 higher than asian males. the descriptive statistics for the mandibular central incisor are shown in table 4. statistically significant differences were found between caucasians and asians, and between african americans and asians (f = 4.46, p = 0.005). statistically significant differences were also found between sexes (f = 4.27, p = 0.04). the males in each ethnic group had between 0.21 mm and 0.77 mm longer roots than the females within their ethnic group. the descriptive statistics for the mandibular lateral incisor root length are seen in table 5. statistically significant differences were found between caucasians and asians, hispanics and asians, and african americans and asians (f = 7.78, p = 0.00). the mean root length for asians was found to be statistically significantly shorter than the other three ethnic groups. the descriptive statistics for the mandibular second premolar root length are shown in table 6. statistically mean mean root relative group sex length sd length sd n caucasians males 16.81 2.05 1.66 0.27 16 females 14.75 1.95 1.62 0.29 14 total 15.85 2.23 1.64 0.27 30 hispanics males 15.96 2.71 1.65 0.34 11 females 14.55 2.38 1.61 0.21 19 total 15.07 2.55 1.63 0.26 30 african americans males 17.12 1.55 1.62 0.13 16 females 15.21 1.76 1.52 0.24 14 total 16.23 1.89 1.57 0.19 30 asians males 15.41 1.71 1.52 0.19 11 females 13.73 1.59 1.40 0.21 15 total 16.23 1.82 1.45 0.21 26 total males 16.44 2.06 1.62 0.24 54 females 14.55 2.00 1.54 0.25 62 total 15.43 2.23 1.58 0.25 116 table 1. descriptive statistics for the maxillary central incisor mean root group sex length sd n caucasians males 16.28 2.15 16 females 15.04 1.94 14 total 15.70 2.12 30 hispanics males 15.86 1.23 11 females 15.34 1.64 19 total 15.53 1.50 30 african americans males 16.63 1.73 16 females 15.64 1.90 14 total 16.17 1.84 30 asians males 15.64 1.64 11 females 14.67 1.01 15 total 15.08 1.38 26 total males 16.17 1.76 54 females 15.18 1.65 62 total 15.64 1.77 116 table 2. descriptive statistics for the maxillary lateral incisor significant differences in mean root length were found between hispanics and african americans, and african americans and asians, and between sexes in each group (f = 6.9, p = 0.000). males in each ethnic group had between 0.30 mm and 0.87 mm longer roots than the females. the largest difference was found between african american males and females. discussion the results of the current study indicate that there is a statistically significant relationship between ethnicity and developmentally short dental roots for the maxillary central incisor, mandibular central and lateral incisors, and mandibular second premolars. this finding is in agreement with lind (1972). overall, asians were found to have the shortest roots for all teeth except the maxillary second premolar as compared to caucasians, hispanics, and african americans. statistically significant differences in relative root length between ethnic groups were found for the maxillary central incisor and second premolar. in the present study, asians and african american females showed a relative root length value less than 1.6 for the maxillary central incisor which indicates a predisposition to developmentally short dental roots for these teeth as previously stated by desai et al. (2006). it is possible that asians and african americans have tall maxillary central incisor crown heights as compared to their root lengths for this tooth differences in root length by race and sex 14 mean root group sex length sd n caucasians males 1.61 0.27 16 females 1.67 0.31 14 total 1.63 0.29 30 hispanics males 1.68 0.23 11 females 1.71 0.29 19 total 1.70 0.27 30 african americans males 1.79 0.52 16 females 1.71 0.25 14 total 1.75 0.41 30 asians males 1.70 0.37 11 females 1.73 0.39 15 total 1.72 0.37 26 total males 1.70 0.37 54 females 1.70 0.31 62 total 1.70 0.34 116 table 3. descriptive statistics for the maxillary second premolar mean root group sex length sd n caucasians males 14.84 1.33 16 females 14.07 1.09 14 total 14.48 1.26 30 hispanics males 14.18 2.04 11 females 13.50 1.47 19 total 13.75 1.70 30 african americans males 14.25 1.99 16 females 14.04 1.43 14 total 14.15 1.73 30 asians males 13.36 1.83 11 females 12.60 1.21 15 total 12.92 1.52 26 total males 14.23 1.82 54 females 13.53 1.42 62 total 13.86 1.65 116 table 4. descriptive statistics for the mandibular central incisor mean root group sex length sd n caucasians males 15.22 1.99 16 females 15.50 1.53 14 total 15.35 1.77 30 hispanics males 15.64 1.58 11 females 14.68 1.60 19 total 15.03 1.63 30 african americans males 15.84 1.50 16 females 15.64 1.57 14 total 15.75 1.51 30 asians males 13.91 1.55 11 females 13.67 1.11 15 total 13.77 1.29 26 total males 15.22 1.79 54 females 14.84 1.63 62 total 15.02 1.71 116 mean root group sex length sd n caucasians males 15.59 2.10 16 females 15.29 2.53 14 total 15.45 2.28 30 hispanics males 14.73 1.03 11 females 14.42 1.59 19 total 14.53 1.40 30 african americans males 16.94 2.50 16 females 16.07 1.81 14 total 16.53 2.21 30 asians males 14.73 1.69 11 females 14.13 1.64 15 total 14.39 1.66 26 total males 15.64 2.15 54 females 14.92 2.00 62 total 15.25 2.09 116 table 5. descriptive statistics for the mandibular lateral incisor table 6. descriptive statistics for the mandibular second premolar edgcomb et al. 15 and results in smaller relative root length values. asians may be particularly vulnerable to developmentally short maxillary incisor roots because they also had the shortest mean root length for this tooth. all four ethnic groups had relative root length values greater than 1.6 for the maxillary second premolar which indicates that this tooth does not appear to be predisposed to being developmentally short. statistically significant differences in mean root length were found between sexes for the maxillary central and lateral incisors, mandibular central incisors and second premolars. furthermore, statistically significant differences were found for relative root length values between sexes for the maxillary central incisors. in the majority of teeth, females had shorter roots than their male counterparts within their ethnic group. this finding was in agreement with kjaer (1995) and lind (1972). there were several limitations to the current study. first, the mesial and distal cervical constrictions and the apices of the teeth were not always clear on the radiographs. this could have introduced measurement error into the results. a second limitation was that although the periapical radiographs were taken using the long cone paralleling technique they were taken by different operators and some magnification, elongation, or foreshortening distortions could have been introduced into the images due to operator variability. however, according to sameshima and asgarifar (2001) the magnification factor associated with periapical films is less than 5%, and intraoral films are accurate within 0.3 mm. a third limitation of the current study is that it could not be confirmed that the subjects were not of mixed ethnic background. the ethnicity of the subjects was identified from their electronic record. a more accurate way to ensure that the subjects were of a homogenous ethnic background would be to question family members, but this was not realistic since the current study was retrospective in nature. conclusions the current study found that asians had the shortest dental root lengths for all teeth measured, except for the maxillary second premolar, as compared to caucasians, hispanics, and african americans. statistically significant differences in root length were found between ethnic groups for the maxillary central incisor, mandibular central and lateral incisors, and mandibular second premolar. significant differences in relative root length values among the ethnic groups were found for the maxillary central incisors. statistically significant differences between sexes were found for the maxillary central and lateral incisors, and the mandibular central incisor mean root lengths, plus the maxillary central incisor relative root lengths. females had shorter roots than their male counterparts within each ethnic group for the teeth measured. literature cited apajalahti s, arte s, pirinen s. 1999. short root anomaly in families and its association with other dental anomalies. eur j oral sci 107:97-101. desai r, vanaki s, puranik r, rashmi g, nidawami p. 2006. a combination of idiopathic generalized short-root anomaly associated with microdontia, taurodontia, multiple dens invaginatus, obliterated pulp chambers, and infected cyst: a case report. j oral pathol med 35:407-409. höltta p, nystrom m, evalahti m, and alaluusua s. 2004. root-crown ratios of permanent teeth in a healthy finnish population assessed from panoramic radiographs. eur j orthod 26:491-497. kjaer i. 1995. morphological characteristics of dentitions developing excessive root resorption during orthodontic treatment. eur j orthod 17:25-34. lind v. 1972. short root anomaly. scand j dent res 80:85-93. sameshima g, asgarifar k. 2001. assessment of root resorption and root shape: periapical vs panoramic films. angle orthod 71:185-189. thongudomporn u, freer t. 1998. prevalence of dental anomalies in orthodontic patients. aust dent j 43:395-398. uslu o, akcam om, evirgen s, cebeci l. 2009. prevalence of dental anomalies in various malocclusions. am j orthod dentofacial orthop 135:328-335. weiland f. 2006. external root resorptions and orthodontic forces: correlations and clinical consequences. prog orthod 7:156-163. differences in root length by race and sex 35 dental anthropology 2020 │ volume 33 │ issue 02 the anthropology of modern human teeth second edition has been published 20 years after the original scott and turner (1997). the first edition made the arizona state university dental anthropology system (asudas) dental morphology data collection methodology accessible to scholars around the world. since that time multiple generations of dental anthropologists have graduated and continued the exploration of information gleaned from modern human and fossil hominid teeth. the second edition closely follows the same outline as the first edition. each chapter has been updated with the inclusion of almost every single published study up to the publication date. the developmental and genetic sections have been expanded. the most obvious difference between the two editions is the addition of an entire chapter focused on dental variation among fossil hominids. g. richard scott was turner’s first graduate student and their close research relationship is the core of this book. scott brings his expertise in covering the breadth of dental anthropology populations studies on european and arctic populations, familial studies on patterns of inheritance, and the possible effects of gene flow on trait expression. this book greatly benefits from christy g. turner ii’s global dental morphology data and his unique slide collection of dental variation and rare traits. both of these researchers have seen almost every dental morphological variation recorded in modern human populations. the addition of two new co-authors helps to round out the scope of this book. grant c. townsend’s extensive research into odontology, dental development, and genetics provides the background to understand the necessity for morphological studies. maría martinón-torres specializes in the dental anthropology of fossil hominins. she brings a unique perspective on dental variation among fossil hominids with a focus on sites in spain and china. the organization is straightforward with a prologue, eight chapters, and an epilogue. the prologue summarizes the present state of dental morphological research. they address potential problems encountered in the process of data collection. finally, dental anthropology class teaching objectives are mentioned. chapter 1 covers the history of dental morphological studies, what has been the research focus of dental anthropologists, who are the key historical figures, and research trajectories through time. chapter 2 is a thorough description of crown and root dental traits in permanent teeth. dental anatomical terminology, direction and positional terminology, and cusp numbers are reviewed. data collection, interobserver error, and intraobserver error are discussed. thirty-six traits are shown with photographs of real teeth and dental casts. each trait is listed with a brief description, observable variants, and which key teeth to be scored. chapter 3 switches directions and introduces ontogeny, dental trait development, asymmetry, intertrait associations, and dental genetics. chapter 4 focuses on the genetic background of dental traits. how are dental traits influenced by intertrait associations and levels of heritability? how is trait expression affected by the combination of genes and environment? chapter 5 looks at the distribution of dental traits along five macro-regional divisions using over 30,000 individuals from turner’s data set. more intra-regional subdivisions have been added since the first edition to provide a more detailed picture. the two regions which benefit the most from the added data sets are sub-saharan africa and north america. the tables and figures help greatly to organize this immense amount of information. the specific dental traits used to define macro-regional dental complexes are explained. chapter 6 introduces the theoretical and methodological issues encountered in population history studies. many studies use either a historical or processual basis for their hypotheses. studies are grouped according to whether they are addressing natural selection, gene flow, gene drift, mutation, or sexual selection. an attempt is made to determine possible adaptive mechanisms for dental traits based on structure, function, strength, or durability. an interesting section mentions the potential of using book review the anthropology of modern human teeth. dental morphology and its variation in recent and fossil homo sapiens. by g. richard scott, christy g. turner ii, grant c. townsend, and maria martinon-torres. cambridge university press. 2018. 396 pp., $44.99 (paperback). isbn:978-1-316-62648-1 36 dental anthropology 2020 │ volume 33 │ issue 02 rare dental traits to determine kinship or marital patterns. the authors mention the level of congruence (or not) dental trait studies have had with linguistic regions, historical records, archaeological evidence, blood group patterns, cranial nonmetric traits, odontometrics, and dermatoglyphics. finally, extensive citations are mentioned for micro-regional studies, which have exploded since the publication of the first edition. chapter 7 goes into detail about the macro-regional dental complexes and how they contribute to the understanding of population history in very deep time. these studies focus on the “peopling of the world” hypothesis which was the driving factor in christy g. turner ii’s lifetime of research. some exploration into the evolution of dental traits is mentioned. in the end all of the data supports an origin of modern humans from africa. chapter 8 is a new addition to this edition focusing on fossil hominids. this is an excellent and much needed overview on fossil hominid dental variation. while the emphasis is on finding a dental complex, which will identify modern homo sapiens, almost every fossil hominid species are represented. twelve potential distinguishing dental traits are examined in detail. while no single dental trait is unique to modern humans, a particular combination and expression of traits may provide some discrimination. a large number of individual hominids is represented. the numerous photographs allowing a side-by-side comparison of individual teeth, more or less to scale, is impressive. the epilogue covers areas that are outside the authors’ research focus including deciduous teeth, dendrochronology, and forensics applications. many things about this edition are incredible achievements. the writing style and tone are comfortable and clear. very complicated concepts are explained well and made accessible. the manipulation and visualization of the huge data set is an accomplishment. the tables, graphs, and figures are well designed and explained within the text. the sheer number of photographs is a huge asset to any researcher. the bibliography in itself is probably the most valuable part of this book. this is a refreshingly inclusive collection of national and international research. the main weaknesses of this edition have to do with being too ambitious with lapses in structure and organization. the flow of the chapter topics can be abrupt. it may have flowed more smoothly with all of the background information first, then introduce the traits, ending with the populational studies. the prologue, epilogue, and chapter 8 feel as if they are tacked on, and not well integrated into the rest of the chapters. this may be a result of the all-inclusive nature of the book, that there is just too much information to fold everything in smoothly. with the exception of chapter 8, the photo quality of the rest of the book is not as good as the first edition. this may be the result of quantity overshadowing quality in the photographs. some of the dental traits are difficult to visualize due to the small size or not enough contrast. overall, this book is a much needed addition to the fields of dental anthropology, dental genetics and development, population history, and fossil hominid research. the numerous photographs and all-inclusive bibliography make this a unique contribution to the field. while the information is too dense to use as a textbook, researchers and advanced graduate students will find this a valuable addition to their libraries. this is a poignant last publication and a fit tribute to the career of christy g. turner ii reference scott, g.r., & turner ii, c.g. (1997). the anthropology of modern human teeth. dental morphology and its variation in recent human populations. cambridge: cambridge university press. christine lee california state university, los angeles 3 dental anthropology 2014 │ volume 28 │ issue 03 diachronic evidence in nonmetric morphological characters of teeth in armenian highland and georgia populations a. yu. khudaverdyan institute of archaeology and еthnography national academy of science, republic of armenia, yerevan dental anthropology, the study of modern and archaeologically-derived human dentitions, is a well-established sub-discipline of physical anthropology. it is defined by hillson (1996:1) as "a study of people (and their close relatives) from the evidence provided by teeth." such research yields information on a variety of topics, including growth and development, health, diet, occupational activity, and biological affinities. this information can be used in studies of individuals as well as populations. the analysis of nonmetric dental traits, when compared with similar studies, can be used to infer biological relationships between populations and track evolutionary variation related to changing settlement patterns. dental morphology can provide insights into phenotypic group differences, and these may be suggestive of differences in genotypic affiliation (varela and cocilovo, 2000). nonmetric dental traits are controlled in large part by genetics and are relatively free of sex and age bias (scott and turner, 1997). the analysis of biological relatedness using dental nonmetric traits has been helpful even in commingled samples when standardized procedures are followed (ullinger et al., 2005). for these reasons, the reconstruction of biological relationships among ancient human groups using teeth is an important research strategy for transcaucasian bioarcheologists. the aim of the present study is to provide new non-metric dental data for ancient transcaucasian groups. several investigations provide information about nonmetric variation from a local scale in human groups from asia and the pacific (hanihara, 1965, 1966; hanihara and minamidate, 1965; sasaki and kanasawa, 1998; kitagawa, 2000), africa (grine, 1984, 1986, 1990; lease, 2003), india (lukacs, walimbe, 1984; lukacs, hemphill, 1991), central asia (rikushina et al., 2003; bagdasarova, 2000), europe (jørgensen, 1956; aksjanova, 1978; segeda, 1993; cucina et al., 1999; gravere, 1999; lease, 2003; coppa et al., 2007; vargiu et al., 2009; zubova, 2010), the near east (smith, 1978; smith et al., 1987; moskona et al., 1998), siberia (khaldeeva, 1979; tur, 2009; zubova, 2008), australia (townsend and brown, 1981; townsend et al., 1986, 1990) and north america (sciulli, 1998, tocheri, 2002; ullinger, 2003; lease, 2003; lease and sciulli, 2005; edgar and lease, 2007). surprisingly, past and present transcaucasian populations have received little attention (kashibadze, 1990, 2006; palikyan, nalban-dyan, 2006; khudaverdyan, 2009, 2011a, b, 2013, 2014). the study of phenotypic diversity can help us understand the evolution and biocultural variation of the ancient and contemporary communities that today inhabit transcaucasian. this will provide a more complete landscape of the dynamics that configure their gene pool. abstract the aim of the study is the assessment of biological distance between populations from armenian highland and georgia based on the frequency of nonmetric odontological traits. these traits are characterized by high inter-population differentiation, low sexual dimorphism, and relatively small intra and inter observer recordation error. this paper presents the results of the odontological differentiation of human populations from armenian highland and georgia. the comparative analysis was carried out on 12 populations. trait frequencies for all populations were analysed using principal component analysis. results support the following conclusions: the populations of armenian highland and georgia can be differentiated as far as the frequency of odontological traits are concerned. biocultural diversity of ancient transcaucasian populations has not been studied extensively, therefore delineating some of the patterns of phenotypic variation may be useful for understanding their ongoing evolution. correspondence to: dr. anahit khudaverdyan abhiram, institute of archaeology and еthnography national academy of science, republic of armenia, yerevan, 0025, charents st.15 fig. 1 locations of transcaucasian groups keywords: dental variation, biological distance 4 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 materials and methods in total, the intergroup analysis included 12 series (table 1) from the territory of transcaucasian (kashibadze, 1990, 2006; khudaverdyan, 2009, 2013, 2014) (fig. 1). we assess dental reduction trends in two regions during three (armenia) and four (georgia) prehistoric transitions, bronze age to modern period. i have examined 6 samples (more than 181 individuals) of bronze and classical periods from the territory of the armenia. the series were grouped according to periods and local groups. the early bronze period (4000-3000 bc) farmer and cattle-breeder landjik represent the kuroarexes population of the armenian highland. the late bronze period sample is represented by remains from one armenian highland site (black fortress). the combination of remains from these two sites is justified for three reasons. first, the small sample sizes for sites (landjik, black fortress) were inadequate (from 10-13 individuals) for subsequent biodistance analysis. second, the landjik, black fortress sites they represent a cemetery from shirak plain (table 2). indeed, the geographic distance among sites a small. finally, analysis of all nonmetric traits revealed no significant differences exist among remains from the two sites, so data from these sites were combined for subsequent statistical analyses (khudaverdyan, 2009). remains from the lchashen site were treated as an independent sample because a sufficient number of crania from burials in sevan pool were available for study (kashibadze, 2006). the bronze age sample is represented by remains from four armenian sites (lchashen, shirakavan, keti, karchakhpyur). two of the four armenian sites, i.e., shirakavan and karchakhpyur represent a samples with an date of 1st century bc 3rd century ad (i.e. ancient time) (kashibadze, 1990, p. 287). the classical period (1st century bc 3rd century ad) samples examined include remains from beniamin, vardbakh, black fortress i, and karmracar (table 2). the small sample sizes for sites of vardbakh, black fortress i, and karmracar were inadequate (from 12-23 individuals) for subsequent biodistance analysis. the beniamin, vardbakh, black fortress i, and karmracar sites represent a cemetery from the shirak plain and the geographic distances among sites are relatively close. after the armenian genocide, v.v. bunak collected a large number of human skulls in 1915 that were victims of the genocide (now housed at museum of anthropology, moscow). the modern population includes remains from these individuals (bingel dag: armenians from musha) (kashibadze, 2006). two bronze period samples from georgia (digomi, mckheti) were analyzed in this investigation. combining the remains from these two sites is justified because of the small number of groups (table 2). the classical period/ late an-tiquity period (1st century bc – 3rd cen-tury ad) country sample name date researchers 1 armenian highland total group: landjik, black fortress c. 40002000bc khudaverdyan, 2009, 2011a 2 armenian highland total group: lchashen, shirakavan, keti, karchakhpyur c. 2000bc c. 1 bc – ad 3 kashibadze, 1990 3 armenian highland lchashen c. 3000 2000 bc kashibadze, 2006 4 armenian highland total group: beniamin, vardbakh, black fortress i, karmrakar c. 1 bc – ad 3 khudaverdyan, 2009 5 armenian highland bingel dag 20th century kashibadze, 2006 6 georgia total group: digomi, mckheti c. 30002000bc kashibadze, 2006 7 georgia total group: chiaturia, mckheti i, mckheti c. 1 bc – ad 3 kashibadze, 2006 8 georgia total group: dzinvali, samtavro, mckheti i, mckheti c. vi x ad kashibadze, 2006 9 georgia total group: dzinvali, adjaria, shatili, adigeya, mckheti c. x xii ad kashibadze, 2006 10 georgia total group: dzinvali, rustavi, sioni, shatili c. xiii – xix ad kashibadze, 2006 11 georgia total group total group kashibadze, 2006 12 georgia dzinvali 20th century kashibadze, 2006 5 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 trait 1 2 3 4 5 midline diastema ¹ 23.7 /17/ 2.4 3.6 10.5 /86/ 9.2 dental crowding 62.5 /16/ 1.2 1.8 78.5 /79/ 3.0 reduced, peg-formed tooth i² (2+3) 0.0 0.0 0.0 10.9 /83/ 1.0 reduced, peg-formed tooth i² (1) 67.5 /15/ 12.9 0.0 65.1 /83/ 19.4 shovelling i¹ 35.8 /15 0.0 0.0 45.1 /62/ hypocone m 2 ∑3,3+ 37.5 /14 34.2 32.7 30.5 /69/ 40.6 cara m 1 (2-5) 31.3 /16/ 43.4 38.7 46.7 /75/ 58.8 m14 14.3 /15/ 16.7 23.3 17.8 /79/ m16 0.0 2.8 3.3 5.8 /52/ m24 64.7 /17/ 78.9 72.4 71.3 /66/ 1ео (3) м¹ 21.5 /16/ 43.4 38.4 41.94 /31/ 41.7 dтс 42.5 /18/ 7.1 64 10 50.9 /57/ dw 42.5 /18/ 16.7 16.7 38.1 /42/ 2 med ii м1 29.2 /17/ 41.7 40.0 53.4 /45/ trait 6 7 8 9 10 12* midline diastema ¹ 4.9 11.4 3.2 3.2 5.2 dental crowding 1.7 0.0 4.6 1.2 1.7 reduced, peg-formed tooth i² (2+3) 3.6 0.0 0.0 0.32 0.0 reduced, peg-formed tooth i² (1) 8.2 0.0 0.0 0.0 0.0 shovelling i¹ 15.5 7.1 7.7 4.0 33.4 hypocone m 2 ∑3,3+ 10.3 23.8 25.7 20.6 32.9 33.3 cara m 1 (2-5) 47.1 43.8 28.6 36.7 60.1 100.0 m14 9.7 10.8 11.8 8.92 5.1 66.7 m16 4.9 5.4 0.0 6.5 2.3 0.0 m24 87.6 93.0 83.6 93.3 95.0 100.0 1ео (3) м¹ 78.6 2 33.3 25.0 38.8 40.5 dтс 8.9 0.0 0.0 6.6 2.1 dw 18.5 28.5 8.3 7.5 0.0 2 med ii м1 14.8 33.3 12.5 17.5 12.5 6 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 samples from georgia exam-ined by this study include remains from chiaturia, mckheti i, mckheti i (total group). inadequate number of remains were available from this site and, there-fore, they were analyzed as a single sam-ple. four early feudal period samples from georgia (dzinvali, samtavro, mckheti i, mckheti / total group/) were analyzed. average feudal period (c. x xii ad) samples examined include remains from dzinvali, adjaria, shatili, adigeya and mckheti. late feudal period (c. xiii xix ad) samples examined include remains from dzinvali, rustavi, sioni and shatili. the modern population includes remains from dzinvali (kashibadze, 2006). human dentitions exhibit highly heritable nonmetric morphological crown and roots traits that vary within and between populations. the term non-metric implies structural variations of individual crown and root forms that are visually scored in two ways: "presence-absence" characters such as furrow patterns, accessory ridges, supernumerary cusps and roots, or, as differences in form such as curvature and angles (hillson, 1996; scott and turner, 1997; zubov, 1973, 1979). numerous studies have demonstrated that morphological dental forms respond to microevolutionary forces of admixture (e.g. turner, 1969; pinto-cisternas et. al., 1995; khudaverdyan, 2011), mutation (e.g. morris et al., 1978), genetic drift (e.g. turner 1969; scott and dahlberg, 1982; segeda, 1993; khudaverdyan, 2009, 2013, 2014; vargiu et al., 2009; zubova, 2008, 2010), and selection (e.g. dahlberg, 1963; scott and turner, 1988), thus evincing their high degree of genetic control. the method a.a. zubova (1973, 1974), the most widely employed system in russian school of anthropology, was used to score non-metric dental traits. these traits are characterized by high inter-population differentiation and the analysis of their occurrence enables researchers to obtain data concerning the genetic relationships between populations identified as falling in different ethnic complexes. odontological traits are used successfully in the description and explanation of both evolutionary and microevolutionary processes. such studies are commonly used to assess specific research questions such as the synchronic biological relatedness of segments of a particular society (e.g. johnson and lovell, 1994), or diachronic changes in trait expressions in a particular region (e.g. lukacs and hemphill, 1991; cucina et al., 1999; gravere, 1999; coppa et al., 2007). since teeth complete their growth during the early stages of an individual’s development, they are strongly determined be genes and their morphological structures are only slightly sensitive to environmental influences. teeth are usually well preserved in archaeological materials and are often the only source of observation of human remains. the following odontological traits were used in this comparative analysis: (1) diastema of i1-i1, (2)crowding of i1; (3)shovelling of i1; (4) reduction of i2 (grades 2+3); (5) reduction of i2 (grade 1); (6) reduction hypocone (forms 3+ and 3) of the upper second molar; (7) carabelli’s cusp on m1; (8) form 1 pa (eo) on m1; (9) fourcusped forms on m1; (10) fix-cusped forms on m1; (11) four-cusped forms on m2; (12) deflecting wrinkle of the metaconid of m1; (13) the variant 2med ii position of the second furrow of the metaconid on m1; and (14) distal crest of trigonid on m1 (table 3). the above-mentioned traits were selected because they meet the following criteria: 1) the traits should not reveal inter-correlations for the frequency of occurrence; 2) they should reveal high inter-group variability; 3) the degree of variant formation cannot change with an individual’s age, 4) it should be easy to find comparative data for different populations. data are subjected to the component (factor) and cluster analysis. a.g. kozintseva and b.a. kozintseva’s statistical package was used (museum of anthropology and ethnography of name of the peter the great, st. petersburg). results and discussion secular dental changes in the populations of the transcaucasian diachronic tendencies in cranial and dental morphology have occurred ever since anatomically modern humans began to populate the planet. one of the major tendencies was the increase of body length. cranially, one of the most important trends was brachycephalization (alexeev, 1974). apart from those tendencies, irregular fructuations in body size occurred, whereas the overall proportions displayed greater stability (godina et al., 2000). a secular increase in body length observed over most of the 20th century was not exceptional. dental changes are related to somatic ones. certain aspects of dentition are rather labile, as evidenced by various patterns of the gracilization process, which is probably continuing. while brachycephalization (or debrachycephalization), gracilization, dental reduction, and the increase of body length may occur in parallel, the causes of those processes probably vary. microevolutionary tendencies may be triggered by ontogenetic changes, specifically acceleration or deceleration of growth caused by endocrine, neurohumoral, trophic, and other factors. with our taking into account the secular changes in the dentition, an adequate reconstruction of population history is hardly possible, especially when issues of continuity versus replacement are discussed. secular 7 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 trait tooth trait definition used in this study (zubov 1968) matching asu dental anthropology system and zubov system asu=zubov midline diastema ui1 space between the upper central incisors equal or larger than 2 mm; 0 – no diastema, space 0=0; 1=1 dental crowding ui2 crowding of the upper lateral incisors; 0 – crowding is not observed; 1 – crowding is observed 0=0; 1=1 shovelling ui1 shoveling of the upper central incisors; observed when the marginal ridges of the incisors are prominent and enclose a deep fossa in the lingual surface of the tooth: 0 – none; 1 – poorly delineated rollers along edges; 2 – well differentiated ridges on both sides, somewhat projecting above the surface; 3 – clearly expressed high ridges on the lingual surface giving the characteristic shovelshaped form 0=0; 1=1; 2=2; 3–6=3 reduced, peg-formed tooth ui2 distal lobe of second incisors reduced enough to produce a peg-shaped form; 0 – no reduction, lateral incisor width approximately 70 to 80% that of central incisor; 1 – lateral incisor mesial-distal width approximately 50% that of central; 2 – conical incisor with a pointed apex; 3 – pegform tooth, crown height considerably less than adjacent tooth 2=2+3 reduced, peg-formed tooth ui2 please follow above sample 0=0; 1=1 hypocone um2 degree of reduction of the hypoconus on the second upper molars; 4 hypocone well developed, forming a distinct disto-lingual corner of the crown, 4– hypocone diminished, not forming a corner, 3+ hypocone very reduced, 3 absence of hypocone 3.5,3=4– carabelli's cusp um1 the small additional cusp on the mesiolingual corner of the upper first molar presents in a variety of different forms; 0 absence, 1 slightly uneven surface due to one or two barely visible grooves, 2 slight swelling limited from the mesial and occulusal sides by a curved weakly expressed groove, 3 groove has character of a cusp, 4 cusp clearly expressed, 5 large free-standing cusp 0=0; 1=1; 2=2; 3–5=3 1 pa (eo) 3 um1 type of structure of the first furrow of the paracone on the first upper molar trait not used in the asu system four-cusped lm1 cusp number mandibular molars 4 4 is highest number of cusps 4=4 four-cusped lm2 4 4 is highest number of cusps 4=4 six-cusped lm1 6 6 is highest number of cusps 6=6 deflecting wrinkle lm1 the deflecting wrinkle is one of the particular formations of the median ridge of the metaconid. the ridge, when the deflecting wrinkle appears, shows a stronger development in either its length or breadth and curves distalward at the central part of the occlusal surface. 0–1=0 2med ii lm1 the variant 2med ii position of the second furrow of the metaconid trait not used in the asu system distal trigonid crest lm1 this trait is characterized by a crest or ridge that courses buccolingually along the distal aspect of the primitive trigonid, represented by the protoconid and metaconid. it often appears as an extension of the distal accessory ridge of the protoconid although the distal accessory ridge of the metaconid may also be involved in forming the crest. 0–1=0 table 3. non-metric dental traits definitions and code matching for the ranked traits used in this study (zubov scheme) and in the arizona state university dental system (asu scheme) cited according to haeussler and turner (1992): 277–278 8 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 changes in dentition over the last few centuries and millennia have been studied in various countries. a diachronic dental crown size reduction has been observed among middle, late and post-pleistocene hominid palaeo-populations and modern human populations (brace, 1976, 1979, 1980; brace and mahler, 1971; brace et al., 1987; brose and wolpoff, 1971; wolpoff, 1971; smith, 1977; frayer, 1977, 1978, 1984; y'edynak, 1989; chamla, 1980; calcagno, 1986; calcagno and gibson, 1988; keiser, 1990; pinhasi, 1998). various researchers report that this trend varies by tooth type and tooth dimension (brace et al., 1987; wolpoff, 1971; frayer, 1978, 1984). it has long been suggested that these changes might be caused by the transition to soft food (dutta, 1983) and the ensuing reduction of functional load. comparative studies of twins (potter et al., 1976), of parent and offspring (goose, 1971) and full versus half siblings (townsend and brown, 1978) substantiate the claim that more than half the variability in tooth crown size could be attributed to genetic factors (brabant and twiesselmann, 1964; townsend and brown, 1978; scott and turner, 1997). other experts point to the importance of environmental or biochemical processes, etc. (dahlberg, 1963; shapiro, 1963). dahlberg (1963) observed considerable population-specific variability in tooth size and form, so he hypothesized that changes in the human dentition are the result of a relaxation of certain environmental pressures. he therefore proposed that european populations have a smaller tooth mass than do populations in "less favoured environments." small teeth may be the outcome of “selection by crowding,” whereby reduced load on the masticatory apparatus causes the eduction of alveolar processes, resulting in too little space for teeth (zubov and khaldeeva, 1989). brace (1963) presented the probable mutation effect theory (pme) that suggests that in the absence of natural selection, mutations will be the main force acting toward a reduction of structural size and complexity of teeth and other organs. thus, developmental processes, controlled by complex genetic mechanisms, will be disrupted resulting in an incomplete or a simplified dental structure (such as the change in cusp pattern). the pme is based on the concept of drift and stochastic microevolutionary mechanisms that act in the absence of selection (sciulli and mahaney, 1991). another possible factor in dental gracilization may be the high occurrence of caries, which mostly affects large teeth with complex occlusal surfaces (khudaverdyan, 2005). these processes demonstrate the importance of cultural factors in dental evolution. transition to agriculture may lead to a reduction of dental size, as demonstrated by p. sciulli (1979), who compared the dentition of hunters and gatherers with that of agriculturalists. it has been demonstrated that the neolithic revolution may have caused an abrupt decrease in tooth size. according to d. frayer (1977), the dimensions of the facial skeleton during the upper paleolithic and mesolithic in europe decreased more rapidly than did the size of teeth. dental reduction in the near east over the last six thousand years was quite pronounced (smith, 1976). as p. smith has shown, the direction of the microevolutionary process was the same, and differences between the near eastern groups were mainly due to various rates of this process and to isolation. dental reduction, therefore, can lead not only to the decrease of between-group variation, but also to an increase. the objective of this study is to compare prehistoric and recent populations of the transcaucasian to trace secular changes in dental morphology. information about the southern gracile dental types can be found in zubov (1979). the southern gracile type has low percentages of carabelli’s trait, somewhat increased frequencies for the distal trigonid crest, м14, м24 and low variant 2 med (khaldeeva, 1992). the southern gracile type is characteristic for fig. 3. ranges of dental non-metric traits in samples from armenian highland (1) and georgia (2) in bronze age: 1 – i1-i1 diastema, 2 i2 crowding, 3 i2 reduction (grades 2+3), 4 i2 reduction (grade 1), 5 double shoveling, 6 hypocone reduction on m2, 7 carabelli cusp on m1, 8 four-cusped m1, 9 six-cusped m1, 10 fourcusped m2, 11 – 1ео (3) м¹, 12 – distal ridge of trigonid, 13 – deflecting wrinkle of metaconid, 14 2 med ii 9 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 peoples of the transcaucasian (kochiev, 1979; kashibadze, 1990, 2006; khudaverdyan, 2009, 2011, 2013, 2014), daghestan (gadjiev, 1979) and bulgaria (minkov, 1979). the 14 traits, their frequencies, and the number of individuals observed for each trait for the armenian highland and georgia samples are provided in table 2. the differentiation which can be traced in transcaucasian populations is demonstrated figures 2 and 3. in the following, patterns of dental reduction in populations of the transcaucasian are described. diastema a “diastema” is a dental term referring to a space or gap between two teeth, and its size depends on that of the alveolar process (zubov, 1973). it is most commonly applied to the space between the two maxillary central incisor teeth (upper front teeth: i1-i1). the secular decrease in the frequency of this trait reflects one of the aspects of dental reduction. the frequency of diastema in the bronze age populations of the armenian highland ranges from 2.4% to 23.7 %. it is rather low in the bronze age population of georgia (fig. 4-1). in the classical period, it drops to (10.5%), and in moderm armenians the occurrence remains low (9.2%). the tendency, therefore, is quite pronounced. the frequency of diastema in the classical period and feudal age populations of the georgia ranges from 3.2% to 11.4 %. i2 crowding crowding (mainly that of incisors) is an anomaly in the position of teeth, being a phenotypic dental response to jaw size reduction. crowding occurs when there is disharmony in the tooth-to-jaw size relationship or when the teeth are larger than the available space. although crowding is morphologically opposed to the diastema, the secular tendencies in these traits are not necessarily opposed; in fact, they sometimes occur in parallel. the frequency of lateral maxillary incisor crowding in populations of the armenian highland ranges from 1.2% to 78.5%. it was high in classical period people of beniamin, black fortress i, vardbakh, and karmrakar. the drop of frequency to 3% in 20th century armenians is rather unusual. crowding of the teeth in early feudal age georgia is higher than in the bronze age. it is rare in georgian populations (fig. 4-2). fig. 4. ranges of dental non-metric traits in samples from armenian highland (1) and georgia (2) in ancient age: 1 – i1-i1 diastema, 2 i2 crowding, 3 i2 reduction (grades 2+3), 4 i2 reduction (grade 1), 5 double shoveling, 6 hypocone reduction on m2, 7 carabelli cusp on m1, 8 four-cusped m1, 9 six-cusped m1, 10 fourcusped m2, 11 – 1ео (3) м¹, 12 – distal ridge of trigonid, fig. 4-1. diastema (i1-i1) in samples from armenian highland and georgia fig. 4-2. crowding (i2) in samples from armenian highland and georgia 10 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 i2 reduction lateral incisors are frequently smaller than medial ones. maximal reduction of the lateral maxillary incisors, ultimately resulting in peg-shaped incisors, was rare of the transcaucasian. a small increase of frequency of grades 2+3 is observed in the classical period from armenian highland (10.9%) and in the bronze age from georgia (3.6%). grade 1 reduction (fig. 4-3) was frequent during the bronze age (landjik, black fortress) and the classical period (beniamin, vardbakh, black fortress i, karmracar) in populations of the armenian highland. its low frequency (19.4%) is observed in modern (20th century) armenians. whereas the frequency of reduction (grade 1) in the bronze age people of georgia is 8.2%, not a single case has been registered from burials of the classical period and feudal age. double shoveling shoveling is a combination of a concave lingual surface and elevated marginal ridges enclosing a central fossa in the upper central incisor teeth. the mesial and distal lingual ridges of the incisors may be elevated producing a 'shovel-shaped' incisor. this trait is quite variable on the world scale and displays clear-cut geographical regularities. according to a. zubov (1973), evolutionary tendencies are quite different: in eastern groups, the trait remained stable or tended to become more common, while the frequencies of the shoveling gene in the west decreased markedly and in a regular fashion. at present, the frequency of the shoveling gene in the west appears to continue dropping, making the east-west differences even more pronounced (zubov, 1973). this process is counterbalanced by admixture. in the bronze age from armenian highland, the mean total shoveling frequency is 35.8, and it increases in classical period (45.1%). people of the classical period exhibit the highest frequency possibly evidencing admixture. it was high and in late feudal age people of georgia (33.4%). in classical times (1st century bc – 3rd century ad) in the caucasus, there was interaction between different ethno-cultural units – iranian-speaking nomads (scythians, sarmatians, sauromatians, saka) (herodotus iv; strabo xi; piotrovskii, 1959) and local populations. the advancement of the scythians, sarmatians and saka in the territory of transcaucasia was accompanied by not only an interaction of various cultural elements, but also admixture. the invasions of various tribes led, in stages, to a mixture of outsiders among the native armenians and a dilution of their ranks on the plateau. the artificial modification of skulls (such as bregmatic, ring deformations of a head was known in the ancient population of the beniamin, shirakavan and karmrakar, vardbakh) and teeth in ancient peoples of the armenian highland may be related to emerging social complexity and the need to differentiate among people, creating a niche for highly visual bodily markers (khudaverdyan, 2011c). molar shape (m2∑3,3+) hypocone (distolingual cusp) reduction of maxillary second permanent molar. dahlberg's diagrams of degrees of cusp reduction were used for recording hypocone expression (zubov, 1973). the total occurrence of reduced forms 3+ and 3 of the upper second molars gradually increases from the bronze age to the 20th century. in the armenian highland, a distinctive feature of the bronze age populations is a relatively high frequency of hypocone reduction on the upper second molar; later, the trait becomes less frequent in groups of the classical period. the population of shirakavan and karchakhpyur (armenia, classical period) is also characterized by a very high of reduction of the hypocone on m2 (45,8%) (palikyan, nalbandyan, 2006). its highest frequency is observed in modern (20th century) armenians (fig. 4-5). in people of the georgia the range of variation is considerable: bronze age (10.3%), classical period (23.8 %), early feudal age (c. vi x ad) (25.7%), middle feudal age (c. x xii ad) (20.6%); late feudal age (c. xiii – xix ad) (32.9%), and modern georgians (20 century) (33.3%). the trait, therefore, is temporally unstable, and its variation is rather erratic. fig. 4-3. i2 reduction in samples from armenian highland and georgia fig. 4-4. double shoveling in samples from armenian highland and georgia 11 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 carabelli cusp on the upper first molar carabelli's trait is a morphological feature that is expressed on the protocone of human maxillary molars. it is a quasicontinuous variable, i.e. it can be either present or absent, but when present, it exhibits continuous variation in expression (sofaer, 1970). the expression of the trait varies from a slight or distinct single furrow, pit, double furrow, y-shaped furrow, or slight protuberance lacking a free apex, to a small, moderate, or large cusp, which occasionally equals in size the main occlusal cusp. a pit and a furrow (single, double, y-shaped) are negative expressions of the trait, whereas a protuberance and a cusp are positive expressions (alvesalo et al., 1975). certain researchers have noted the frequency of this trait has increased over the last centuries (brabant and twiesselmann, 1964; donina, 1969). a similar tendency is observed in armenian highland groups (bronze age: 31.3 – 43.4%; classical period: 46.7%, moderm armenians: 58.8 %). in people of the georgia the variation range is considerable: bronze age 47.1%, classical period 43.8 %, early feudal age (c. vi x ad) 28.6%, middle feudal age (c. x xii ad) 36.7%; late feudal age 60.1%, modern georgians 100%. number of cusps on the lower molars the occurrence of four-cusped lower first molars in the bronze age population of the armenian highland ranges from14.3 23.3% (fig. 4-7). people of the burial from lchashen exhibit the highest frequency. in people of the classical period of the armenian highland the mean total four-cusp score is 17.8%. the frequencies of four-cusp lm1 in populations of georgia range from 5.1% to 66.7 %. its highest frequency is observed in modern georgians (dzinvali). in populations of the armenian highland, the frequency of the four-cusped lower second molars tends to increase over time. people of the georgia display a high degree of lower second molar cusp reduction (fig. 4-8). the frequency of the sixth-cusp on the lower first molar is low in nearly all populations of the transcaucasian. the trait is virtually absent in the bronze age population (landjik, black fortress) of the armenian highland and early feudal age of the georgia (fig. 4-9). people of the classical period of the armenian highland (5.8%) fig. 4-5. molar shape in samples from armenian highland and georgia fig. 4-6. carabelli cusp in samples from armenian highland and georgia fig. 4-7. four-cusp lower first molars in samples from armenian highland and georgia fig. 4-8. four-cusp lower second molars in samples from armenian highland and georgia 12 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 and middle feudal age of the georgia (6.5%) exhibit the highest frequencies of the sixth cusp. type 3 of the first eocone groove on the upper first molar (1 eo (3) on m1) the frequency of type 3 of the first eocone groove on the upper first molar in populations of the bronze age armenian highland ranges from 21.5% to 43.4%. the population of the classical period (41.94%) and the early 20th century armenian series described in bingel dag (41.7%) reveals rather similar frequencies (fig. 4-10). populations of the bronze age display a high degree of type 3 of the first eocone groove on the upper first molar. the trait becomes less frequent in groups of the classical period (33.3%) and even rarer in early feudal age samples (25.0%). distal trigonid crest (dtc) this trait is ancient and stable. some specialists believe it is highly diagnostic (zubov, 1973, 1979; khaldeyeva, 1992). discrete dental traits are under genetic control (nichol, 1990; scott, 1973; scott and turner, 1997) and can be used to estimate genetic relationships among populations (coppa et al., 2007; haydenblit, 1996; howell and kintigh, 1996; irish, 2005, 2006; scott and turner, 1988, 2006; sofaer et al., 1986). the frequency of distal trigonid crest in populations of the bronze age armenian highland ranges from 7.1% to 42.5%. in the classical period from the armenian highland, the frequency of the distal trigonid crest is 50.9; it decreases in 20th century armenians (fig. 4-11). people of georgia display a low incidence of the distal trigonid crest (bronze age 8.9; middle feudal age (c. x xii ad) 6.6 %; late feudal age 2.1%). deflecting wrinkle of metaconid (dw) the deflecting wrinkle is a particular formation of the median ridge of the metaconid. when the deflecting wrinkle is present, the median ridge shows a stronger development in either its length or breadth and curves distalward at the central part of the occlusal surface. this character was first described by f. weidenreich (1937) in his papers on sinanthropus and gigantopithecus, and subsequently, von g.h.r. koenigswald (1952) drew attention to the deflecting wrinkle in the deciduous mandibular molars in modern javanese. fig. 4-10. type 3 of the first eocone groove on the upper first molar in samples from armenian highland and georgia fig. 4-11. distal trigonid crest in samples from armenian highland and georgia fig. 4-9. sixth-cusp lower first molars in samples from armenian highland and georgia fig. 4-12. deflecting wrinkle of metaconid in samples from armenian highland and georgia 13 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 in addition, the frequency distribution of this character in japanese permanent molars was reported by m. suzuki and t. sakai (1956) and in japanese permanent and deciduous molars by k. hanihara et al, (1964) and k. hanihara (1970). in bronze age armenians (landjik, black fortress, 42.5%), the frequency of the deflecting wrinkle of metaconid is higher than classical period (38.1%). it was low in bronze age people of georgia (18.5%), being maximal in the classical period (28.5%) (fig. 4-12). interestingly, the frequency of the deflecting wrinkle in early feudal age (8.3%) and middle feudal age samples (7.5%) is low. 2(ii) med 2(ii) med is the notation for an odontoglyphic trait on the metaconid (med) of lower molars. 2 (ii) indicates that furrow 2 (a second order furrow that occurs closer to the fovea centrale than furrow 1) goes into furrow ii (a first order furrow that separates the protoconid from the metaconid) (zubov, 1973). the frequency of 2(ii) med in populations of the bronze age armenian highland ranges from 29.2% to 41.7%. in a classical period sample from the armenian highland, the 2(ii) med frequency is 53.4. the trait is low in a bronze age population in georgia (14.8%). in classical period georgia, the frequency of the 2(ii) med is 33.3, and it decreases in feudal age (early feudal age 12.5 %, middle feudal age 17.5 %; late feudal age 12.5 %). figures 2 and 3 presents the differentiation of the comparative populations from armenian highland and georgia (bronze age and classical period). teeth of the population from armenian highland (bronze age) are characterized by a low frequency of carabelli’s cusp on m1, a low frequency of six-cusped forms on m1. and the 1ео (3) on м¹. the occurrence of pronounced reduction of upper second incisors was not recorded (variants 2 and 3). the frequency of crowding, diastema, reduction of incisors (grade 1), hypocone reduction of maxillary second permanent molar (m2∑3,3+), four-cusp lower first molars, distal ridge of trigonid and deflecting wrinkle of metaconid was very high (fig. 2). teeth of the population from georgia (bronze age) are characterized by a high frequency of carabelli’s cusp on m1, six-cusped lower first molars, four-cusped lower second molars, and type 3 of the first eocone groove on the upper first molar. the frequency of the distal trigonid crest on m1, double shoveling, reduction of incisors (grade 1), hypocone reduction of maxillary second permanent molar, four-cusped lower first molars and the deflecting wrinkle is moderately higher in the population from the armenian highland (classical period) that the average value for georgian populations (fig. 3). comparative analysis table 4 presents data concerning the frequency of the occurrence of 10 odontological traits in 11 populations of the armenian highland and georgia. the frequency of traits in percents was converted into frequencies expressed as radians. a modified set of initial data was used to assess the degree of differentiation by means of principal component analysis. this method converts original traits (in radians) into new traits (meta-traits) that are called principal components. the principal component analysis reduces the multidimensional set of variety to two or three-dimensional level, losing only a small percent of information. taking into account the character of the connection between attributes in this component, it is possible to tell that the large values up to the first dimension axes fig. 4-13. 2(ii) med in samples from armenian highland and georgia trait i ii iii i1-i1 diastema 0.597 -0.324 0.745 i2 crowding 0.541 0.116 0.117 hypocone reduction on m2 0.494 -0.746 0.351 carabelli cusp on m1 -0.421 0.672 0.632 four-cusped m1 0.979 0.501 -0.492 four-cusped m2 -0.814 -0.134 0.541 distal trigonid crest -0.158 0.689 0.221 deflecting wrinkle of me-ta-conid 0.771 0.352 0.426 1ео (3) м¹ 0.686 0.511 -0.269 2 med ii м1 0.501 0.203 -0.462 values 54.561 28.671 20.352 тable 4. elements of three initial components for 11 groups 14 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 (correspond to groups with four-cusped lower first molars (0.979), the deflecting wrinkle (0.771), the 1ео (3) м¹ (0.686), diastema (i1-i1) (0.597), i2crowding (0.541), and 2 med ii м1 (0.501). a negative weight is associated with four-cusped lower second molars (-0.814). maximal values for the second component (28.6% of the total variability) are for distal ridge of the trigonid (0.689), the carabelli cusp on the upper first molar (0.672), type 3 of the first eocone groove on the upper first molar (0.511), and four-cusped lower first molars (0.501). the negative weight is associated with hypocone reduction of the maxillary second permanent molar (-0.746). the third component accounts for 11.4% of intergroup variation. the strongest weights are with the diastema (i1-i1) (0.745), carabelli cusp on the upper first molar (0.632), and four-cusped lower second molars (0.541). for positive coordinates of the first axis, the most discriminating dental traits are the four-cusped lower first molars, the deflecting wrinkle, and type 3 of the first eocone groove of the upper first molar. the first two traits show higher frequencies in the lchashen (3), landjik, black fortress (1) and beniamin, vardbakh, black fortress i, and karmracar (4) samples, and slightly lower frequencies in the groups from georgia. for negative coordinates, the most significant trait is fourcusped lower second molars, which show higher frequencies in the groups from georgia. next, we applied the cluster analysis (fig. 5). two main clusters are illustrated in the dendrogram, obtained by using hierarchic method from the first 3 axes. the first cluster is represented by bronze age samples from the armenian highland, differentiated from the second cluster composed of all the other groups. within the latter, two sub-groups can be shown. the first is formed by the bingel dag (20th century armenian) and the feudal and classical periods samples of georgia. the classical period sample can be chronologically placed between the early feudal age and middle feudal age periods. they may have maintained archaic traits because of their geographical isolation. the 2 supgroup consists of the digomi, mckheti (bronze age) and the late feudal age samples. from the analysis of non-metric dental traits, a common biological background can be hypothesized among the populations that inhabited transcaucasian. the armenian highland groups perfectly fit this pattern, showing a high degree of biological continuity between the two periods (bronze age classical period). the 20th century armenians (bingel dag) are strictly linked between the groups from georgia (feudal and classical periods). clear affinities are visible between the samples from georgia. comparative analysis reveals that the populations of the armenian highland and georgia differentiated as far as the frequency of odontological traits is concerned. armenian highland samples are characterised by a different frequency in trait reduction compared to the series from georgia. morphological traits of teeth (odontological traits) differentiated markedly between the comparative populations. therefore, they provide a good tool for studying the biological differentiation of skeletal populations. diachronic changes in nonmetric morphological characters of teeth in the armenian highland and georgia populations occurred at different rates for different traits. fig. 5. cluster tree: 1 armenian highland (bronze age), 2 (bronze age and classical period), 3 armenian highland (bronze age), 4 armenian highland (classical period), 5 armenian highland (modern population), 6 georgia (bronze age), 7 georgia (classical period), 8 georgia (early feudal period), 9 georgia (average feudal period), 10 georgia (late feudal period), 11 georgia (feudal period) 15 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 literature cited aksjanova ga. 1978. some dental material in connec 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tion. am j phys anthropol 78: 17–36 zubov a.a. 1968 . odontology: a method of anthropo logical research. moscow: science. zubov aa. 1973. ethnic odontology. moscow: science. zubov aa. 1974. odontoglyphics. in: zubov aa, editor racialgenetic processes in ethnic history. moscow: science, p 11-42. zubov aa. 1979. conclusion. in: zubov aa, khalde yeva na, editors, ethnic odontology of the ussr. moscow: science. p. 229-254. zubov aa, khaldeeva на. 1989. odontology in mod ern anthropology. moscow: nauka. zubova av. 2008. anthropological structure of the pop ulation of western siberia during epoch of the devel oped and late bronze. ph.d. dissertation. novosi birsk. zubova av. 2010. the population of a pit grave culture al-historical generality in light odontologic data. bul letin of archeology, anthropology and ethnography 2 (13):85-95. michael 2016.1 32 dental anthropology 2016 │ volume 29 │ issue 01 keywords: histology, wilson bands, health, bioarchaeology the classic period maya (a.d. 250-900) was characterized by social stratification, emergence and expansion of elite classes, and integration of large urban centers (cucina and tiesler, 2003). during this period, the maya incorporated multiple types of burial sites into their mortuary program across the ancient landscape. traditionally, archaeologists have focused on the excavation of elite structures and tombs in the maya area, so comparatively little research has been conducted on the bioarchaeological analysis of non-elite maya burials from mortuary sites outside of civic-ceremonial centers. this study analyzed the dental remains of non-elite individuals distinguished in death by placement in two peripheral locations, sapodilla (sdr) and caves branch (cbr) rockshelters, in central belize. three indicators of stress (dental caries, linear enamel hypoplasia, and wilson bands) were collected and estimations of age at defect formation were calculated to determine if these peripheral non-elite groups exhibited stress indicators in frequencies comparable to elite groups in the area. this study makes two original contributions: 1) the analysis of an understudied maya mortuary sample using a method (dental histology) that is not widely applied in the regional bioarchaeology literature; and 2) the assignment of age at defect estimation to better interpret episodic health stress events during life. using these data, rockshelter burials can be compared to two other main mortuary site types in the area, caves and surface sites, to better understand maya mortuary behavior. investigations of rockshelter burials, especially those of the highly socially stratified classic period, will help to close the gap between the much-studied elite class and those many communities that existed independently or semi-independently from urban site cores. enamel defects can be seen macroscopically on the enamel crown as hypoplasias, taking furrow or pit forms. microscopically, the defects present as wilson bands, which are visualized as areas of disrupted ameloblast activity when the enamel is viewed in crossabstract objectives: investigations of dental health in the maya region have frequently focused on individuals buried at urban sites rather than in peripheral or intermediary zones. this study presents a dental analysis of a different type of mortuary sample, those persons buried in two non-elite peripheral rockshelters, in central belize using a combined dental microand macrodefect approach to interpret health experience. materials and methods: a total of 22 teeth (permanent mandibular canines, and mandibular and maxillary third molars) from the two sites were assessed for dental caries, enamel hypoplasias, and wilson bands. the maximum and minimum ages of microdefect formation for each tooth was calculated. results: carious lesions were infrequently represented in the sample, while linear enamel hypoplasias were expressed in less than half the sample. wilson bands, conversely, were present in nearly every tooth indicating that the rockshelter populations experienced more acute stress. individuals interred at caves branch rockshelter were affected earlier in life based on analysis of mandibular canines. conclusion: non-elites buried in rockshelters in central belize had similar dental health experiences when compared with individuals buried at elite centers. at least in terms of oral health, peripheral communities in this area were not adversely affected by their distance from urban core sites *correspondence to: amy michael department of anthropology, michigan state university, east lansing, mi 48824, e-mail: michae76@msu.edu histological analysis of dentition in rockshelter burials from two sites in central belize amy r. michael 1* 1department of anthropology, michigan state university, east lansing, mi 48824 this paper is one of the winners of the albert a. dahlberg prize awarded at the annual meeting of the american association of physical anthropologists in 2016. 33 dental anthropology 2016 │ volume 29 │ issue 01 section. hypoplasias, observed externally, and wilson bands, viewed internally, are indelible markers that indicate a generalized systemic response to stress. the etiology of both defect types is not conclusively understood (hillson 2014), but a combined study of hypoplasias, carious lesions, and wilson bands allows for more nuanced conclusions about health experience to be drawn from a particular sample. if only macroscopic indicators of health stress were observed, the burial populations may appear to have had a more positive health experience than was their reality. however, by analyzing the teeth for three defect types, it is possible to observe more defects at more age ranges, resulting in a more complete picture of episodic health stress in the individual. health experience has historically been measured in human skeletal remains as a physiological disruption resulting in some kind of osteological or dental manifestation of pathology. the physical embodiment of poor health has often been read in the assessment of dental pathology in particular, but a conflation of “health” and “stress” is not intended in this study, but the limitations of interpreting dental pathological conditions are acknowledged here. recently, bioarchaeologists have made increasing efforts to critically evaluate health studies and stress markers, drawing more conclusions from the incorporation of theoretical models and data from fields of epidemiology, primatology, and clinical biology (gowland 2015; temple and goodman 2014). for this sample, dental pathological conditions are still used as a proxy of health experience, but the complexities of individual well-being cannot possibly be totalized by observable defects. it is recognized that intangible processes and states of emotional being that leave no inscription on the archaeological record and are difficult to measure on the physical body contribute to overall health experience. to mitigate this fact, multiple dental pathological conditions are combined to determine the extent of expression between and among individuals at these rockshelter sites. these baseline data then allow for the proposition of larger anthropological questions of health experience as more archaeological data becomes available. specifically, five research questions were asked of this sample: 1) what is the age at defect formation range and mean age at defect formation for each tooth?; 2) how many wilson bands were observed for each tooth?; 3) how many enamel hypoplasias were observed for each tooth?; 4) how many carious lesions were observed for each tooth?; and 5) what is the relationship, if any, between dental macroand microdefects? biocultural context the assessment of rockshelter burials in the maya region is still a relatively new endeavor and certainly part of an ongoing focus on analyzing non-elite burial populations (dunham et al., 1998; glassman and villarejo, 2005; goldstein and prufer, 1999; saul et al., 2005; scott and brady, 2005; wrobel, 2008). the data presented in this paper contribute to the continuing collection of information about the lifeways and social identities of individuals from rural communities. frequently, archaeologists have posited that cave access was governed in part by social status, whereby elites controlled large darkzone caves for the purposes of ritual activity while non-elite activity was relegated to the smaller, less visually impressive caves and rockshelters (awe et al., 1998; graham, 1980; peterson, 2006; reents, 1980; wrobel et al., 2009). the debates over cave and rockshelter use continue in the literature, so the biological data presented here can usefully augment current and future archaeological data collected from these mortuary spaces. sapodilla rockshelter (sdr) is situated near a small tributary of the caves branch river system within the northern portion of the caves branch river valley in central belize. over the course of two field seasons of the central belize archaeological survey (cbas), the presence of 40 – 50 primary burials, commingled human and faunal bones, ceramics, and lithics was confirmed (michael and burbank 2013). ceramic types recovered at sdr reveal that the use of the site was predominantly limited to the protoclassic and early classic periods (michael and burbank 2013). the mortuary patterns and artifact assemblages appear similar to another peripheral site, caves branch rockshelter (cbr), located approximately 1 kilometer away (glassman and bonor, 2005; wrobel, 2008). some evidence for post-mortem secondary manipulation of remains was noted, as one nearly complete burial was absent the cranium yet the mandible was present, and two isolated skulls were discovered. burials at sdr were easily individualized since interments were either undisturbed or only slightly commingled. teeth were mostly retained in the skull or were scattered in close proximity to the body. caves branch rockshelter, situated in the caves branch river valley east of the present-day belizean capital of belmopan, was first excavated by juan luis bonor in the mid-1990s after a number of looting events (glassman and bonor, 2005). this salvage operation yielded 32 primary burials, but dense commingling contributed to the countless bone fragments mixed throughout the burial matrix. following bonor’s work, wrobel continued excavations at cbr during 2005-2007 with the belize valley archaeological reconnaissance (bvar) project and again in 2015 with cbas. all cbr excavations demonstrated that the site was unrestricted by sex or age, further sug34 dental anthropology 2016 │ volume 29 │ issue 01 gesting that the mortuary regulations that governed interment in rockshelters were inclusive. attendant grave artifacts were sparse and utilitarian reflecting use consistent with a rural farming population (wrobel, 2008). based on excavations to date, an estimated 400-500 individuals may be interred at the site (wrobel et al., 2009). the ceramic assemblage spanned a large period of time from the formative period to the terminal classic (bonor, 2002; wrobel et al., 2009; wrobel, 2008). however, the diagnostic ceramics interred as grave goods were largely from the late preclassic, indicating that the most intensive use of the rockshelter likely occurred during this period (wrobel, 2008a). two burials were subjected to ams dating and returned late preclassic and late classic dates suggesting that use may not have been punctuated, but rather persistent (to varying degrees) through time. during the late preclassic, there is no evidence for urban centers in the valley, further underscoring the use of the rockshelter by agrarian communities (wrobel, 2008a). materials and methods for this study, two tooth classes (permanent and deciduous) mandibular canines, and maxillary and mandibular third molars were selected for analysis following danforth’s (1989) study on pre-hispanic maya burials (tables 1 and 2). left teeth were preferentially selected, but when not available the antimere was collected for analysis. due to similarity in enamel formation rates, both the mandibular and maxillary third molars were selected when either was present. prior to thin sectioning for microscopic analysis, data were collected on dental caries and enamel hypoplasias following buikstra and ubelaker (1994). enamel hypoplasias were scored using a combination of the “thumbnail” test and taking an impression in putty. the putty records both slighter expressions of horizontal grooves, as well as pit defects that may not be as immediately visible during the thumbnail test. color and width of the hypoplasias were not recorded, as these data have not been demonstrated to provide any useful biological information (buikstra and ubelaker 1994). fitzgerald and saunders (2005) also stated that variables other than defect presence do not factor into the threshold level or denote severity of the defect. to identify wilson bands, the parameters advocated by hillson (2014:174-175) ,which were adapted from rose et al. (1978:513), and goodman and rose (1990:93) were first considered as the standard observation and identification method for this project. because there is largely no congruent definition in the literature as every author chooses biological criteria and visual representation to prioritize, it was determined that enamel disruptions would be recorded as wilson bands if two of the three criteria were met, following a recent wilson band study done by reeves (2013:42): 1. the stria appears darker and wider than surrounding striae, extending clearly from the dento -enamel junction to the enamel surface 2. the stria exhibits rod disorganization on examination at 1000x magnification 3. the stria has a corresponding darkened stria in the lingual enamel other criteria could potentially be added to this list, but the general presentation of disorganized enamel prisms, darkened striae, and bilateral expression are repeated most frequently throughout the literature. each sample was impregnated with a resin/ hardener mixture and cut in midline. one thin section of approximately 80-100µm (fitzgerald and rose, 2000; hillson, 2014) was created for examination of the internal surface. thin sections were analyzed using a standard light transmitted binocular led digital compound microscope with 3d stage and 9mp camera attachment from united scope. the amscope 3.7 software included with the microscope was used to image the samples. the digital camera attachment provided a live feed to the computer, as well as an image capture feature. thin sections were first magnified at 1000x to identify defects, then they were observed and photographed between 400 – tooth type right left mandibular canine 4 6 maxillary third molar 0 0 mandibular third molar 0 0 deciduous mandibular canine 3 1 total 7 7 table 1. distribution of teeth in the sample from cbr tooth type right left mandibular canine 5 1 maxillary third molar 1 0 mandibular third molar 0 1 deciduous mandibular canine 0 0 total 6 2 table 2. distribution of teeth in the sample from sdr 35 dental anthropology 2016 │ volume 29 │ issue 01 600x. following cook (1981), danforth (1989) developed a population-specific age-at-defect formation schedule for maya dental remains (deciduous canines, permanent canines, third molars). danforth (pers. comm. 2011) stated that it would be reasonable to use these standards for the rockshelter samples. measurements of the location of the wilson bands were taken along the dej with the cej acting at the zero point. for instance, if a wilson band was recorded at 2.25mm, that means that the defect began 2.25mm from the cej. these measurements were matched to the appropriate increment for each tooth class. for example, if a defect in a third molar of a female was noted at 3.1mm from the cej, the associated increment would be in danforth’s dej zone 5 and the associated age range would be 10.7 – 11.3 years; (table 3; see tables 4 and 5 for other tooth classes). in instances where the sex of the individual was estimated, then the male or female age range was used. the majority of the individuals from cbr and sdr do not have sex estimations, and the combined age ranges were employed. table 3. age at development for mandibular third molars* (adapted from danforth 1989) dej zone amscope measurement (mm from cej) age in years (males) age in years (females) age in years (combined sexes) 1 6.01 – 7.0 9.0 – 9.6 9.1 – 9.6 9.0 – 9.6 2 5.01 – 6.0 9.6 – 10.3 9.6 – 10.2 9.6 – 10.2 3 4.01 – 5.0 10.3 – 10.9 10.2 – 10.7 10.2 – 10.8 4 3.01 – 4.0 10.9 – 11.6 10.7 – 11.3 10.9 – 11.4 5 2.01 – 3.0 11.6 – 12.3 11.3 – 11.8 11.4 – 12.0 6 1.01 – 2.0 12.3 – 13.0 11.8 – 12.3 12.0 – 12.7 7 0.0 – 1.0 13.0 – 13.6 13.0 – 13.6 *the same chart was used for maxillary third molars based on the very similar development times (logan and kronfield 1933) dej zone amscope measurement (mm from cej) age in years (males) age in years (females) age in years (combined sexes) 1 11.01 – 12.0 0.7 – 1.1 0.5 – 0.9 0.6 – 1.0 2 10.01 – 11.0 1.1 – 1.5 0.9 – 1.3 1.0 – 1.4 3 9.01 – 10.0 1.5 – 1.8 1.3 – 1.7 1.4 – 1.8 4 8.01 – 9.0 1.8 – 2.2 1.7 – 2.1 1.8 – 2.1 5 7.01 – 8.0 2.2 – 2.6 2.1 – 2.5 2.1 – 2.5 6 6.01 – 7.0 2.6 – 3.0 2.5 – 2.9 2.5 – 2.9 7 5.01 – 6.0 3.0 – 3.4 2.9 – 3.3 2.9 – 3.3 8 4.01 – 5.0 3.4 – 3.8 3.3 – 3.7 3.3 – 3.7 9 3.01 – 4.0 3.8 – 4.1 3.7 – 4.0 3.7 – 4.1 10 2.01 – 3.0 4.1 – 4.5 4.0 – 4.4 4.1 – 4.5 11 1.01 – 2.0 4.5 – 4.9 4.4 – 4.8 4.5 – 4.9 12 0.0 – 1.0 4.9 – 5.3 4.9 – 5.3 table 4. age at development for mandibular canines (adapted from danforth 1989) 36 dental anthropology 2016 │ volume 29 │ issue 01 results table 6 summarizes the data collected for the sdr sample. six individuals were represented in the sample, but only two of these burials retained more than one desired tooth. of the eight teeth available, none exhibited carious lesions, three showed linear enamel hypoplasias, and all but one tooth had wilson bands. the number of wilson bands in each tooth class and the average age point estimate for each tooth class is summarized in table 7. with one exception, the teeth were all mandibular canines with wilson band formation occurring as early as 2.1 years (burial 17) and as late as 4.9 years (burials 9 and 13). the number of wilson bands per tooth was five or under for six of the seven teeth with microdefects. burial 17, exhibiting 12 wilson bands, was an outlier. interestingly, burial 17 was the only individual in this sample interred in the liminal zone between the rockshelter overhang (where most skeletal remains were found) and the small dark zone cave. this burial was also distinguished by the hundreds of shell tinklers forming a belt and bracelet on the body; no other burial at sdr was as decorated. table 8 summarizes the data collected for cbr. of the fourteen teeth available, all were from different individuals. only two of these teeth exhibited carious lesions, while six teeth demonstrated at least one linear enamel hypoplasia. every tooth in the sample expressed at least one wilson band. the earliest age of wilson band formation in the deciduous teeth occurred at 0.33 – 0.42 years (burial 19) and the latest dej zone amscope measurement (mm from cej) age in months (combined sexes) 1 7.01 – 8.0 5 – 6 (in utero) 2 6.01 – 7.0 7 8 (in utero) 3 5.01 – 6.0 9 (in utero) – 1 (post -birth) 4 4.01 – 5.0 2 – 3 5 3.01 – 4.0 4 – 5 6 2.01 – 3.0 6 – 7 7 1.01 – 2.0 8 – 9 8 0.0 – 1.0 10 – 11 table 5. age at development for deciduous mandibular canines (adapted from danforth 1989) burial tooth no. of caries no. of hypplasias no. of wilson bands min. age max. age point estimate age burial 6 rc_ 0 2 4 3.7 4.5 4.1 burial 7 rc_ 0 0 5 2.5 3.7 3.1 burial 9 rc_ 0 0 4 3.3 4.9 4.1 burial 10 rm3 0 0 0 n/a n/a n/a burial 10 rc_ 0 1 2 3.3 4.1 3.7 burial 13 lm3 0 0 3 11.4 12.0 11.7 burial 13 lc_ 0 2 4 2.5 4.9 3.7 burial 17 rc_ 0 0 12 2.1 4.1 3.1 tooth class number of wilson bands in entire tooth class point estimate of average affected age mandibular canine (n=6) 31 3.63 third molar (mandibular and maxillary) (n=2) 3 11.7 deciduous mandibular canine (n=0) n/a n/a table 6. summary of data collected for sdr table 7. summary of sdr sample: wilson bands and ages 37 dental anthropology 2016 │ volume 29 │ issue 01 age at defect formation in the deciduous teeth occurred at 0.5 – 0.75 years (burial 71). for the permanent teeth, the earliest age at defect formation was 1.3 years (burial 51) and the latest was 4.5 years (burial 46c/42). table 9 summarizes the number of wilson bands in each tooth class and the average age at defect formation for each tooth class. discussion and conclusions the rockshelter burials investigated in this paper provide baseline data for understanding rural burial populations in central belize. unfortunately, the samples are too small to present statistically significant results, but the descriptive data do demonstrate some patterns. carious lesions were rarely present at either site, a trend that follows other sites in central belize (slon and michael, 2013). hypoplasias were always linear in formation, but at both sites the total frequency of hypoplastic defects was under 50% for the sample. nearly all teeth expressed at least one wilson band indicating that these defects, signaling more acute stress events (wright, 1990), were the norm in these rockshelter burials. the etiology of these microdefects is still not conclusively known, but the disruption of the enamel prisms can, at minimum, be understood to be reflective of some stress event. of the 22 teeth in the sample, 12 exhibited wilson bands without presentation of enamel hypoplasias demonstrating that the presence of one defect does not necessarily predict the presence of the other. in fact, the burial with the most microdefects (burial 17 from sdr) showed no linear enamel hypoplasias. the average ages at defect formation for each tooth type demonstrate that individuals at cbr were affected by health stress somewhat earlier (2.96 years burial tooth no. of caries no. of hypoplasias no. of wilson bands min. age max. age point estimate age burial 2 lc_ 0 2 1 2.5 2.9 2.7 burial 9 rc_ 0 5 3 2.6 3.4 3.0 burial 10 lc_ 0 3 1 2.1 2.5 2.3 burial 11 lc_ 0 0 3 3.0 3.8 3.4 burial 19 rc_ 1 0 1 0.33 0.42 0.38 burial 23b rc_ 0 0 1 0.5 0.58 0.54 burial 36a rc_ 0 0 1 0.5 0.58 0.54 burial 38 rc_ 0 0 3 2.9 3.3 3.1 burial 46c/42 lc_ 0 1 9 1.8 4.5 3.15 burial 51 rc_ 0 2 7 1.3 4.0 2.65 burial 63 lc_ 0 0 3 2.9 3.3 3.1 burial 71 lc_ 0 0 3 0.5 0.75 0.63 burial 86 rc_ 0 1 7 2.2 3.8 3.0 burial 246 lc_ 1 0 6 2.0 4.4 3.2 table 8. summary of data collected for cbr tooth class n number of wilson bands in entire tooth class point estimate of average affected age mandibular canine 10 43 2.96 third molar (mandibular and maxillary) 0 n/a n/a deciduous mandibular canine 4 6 0.52 table 9. summary of cbr sample: wilson bands and ages 38 dental anthropology 2016 │ volume 29 │ issue 01 for the mandibular canine), while health stress occurred later at sdr (3.63 years for the mandibular canine). deciduous canines, only present at cbr, expressed an average age at defect formation at 0.52 years. third molars, only present at sdr, expressed an average age of defect formation at 11.7 years. what can be gleaned from this project is that, largely, the individuals buried at these two rockshelter sites did not experience overwhelming dental health disturbances. these rural communities may once have been assumed to have suffered greater health disparities due to their lower social status, but that hypothesis is proven incorrect here. previous bioarchaeological research has focused on health experience leading up to (or at the time of) “collapse” when the maya were re-organizing their political alliances and social structure (cucina and tiesler, 2003, 2005; danforth, 1989, 1997; gerry, 1997; storey, 1997; white et al., 2001; white, 1997, 2005; wright, 1997; 2006), or during the contact period when the maya were introduced to new biological and social stresses brought on by the arrival of the spanish (danforth, 1989; wright, 1990). neither of these periods, in spite of extraordinary cultural change, has been shown to have a significant effect on the development of wilson bands and/or enamel hypoplasias. while this study does not focus on periods of social change, the similar results cautiously suggest that residence in peripheral communities (rather than urban centers) did not result in negative biological consequences. non-elites living in rural settlements both adapted to and acted in concert with their surroundings, responding to both environmental and social pressures. the addition of more health data from rockshelter sites in central belize, as well as other classic period rockshelters throughout the country, are necessary to determine the extent to which residence in peripheral zones affected health experience. these data indicate that a binary model of health stress (e.g. elites did not suffer, while commoners suffered greatly) likely does not encapsulate the experience of the classic period maya. acknowledgements dr. gabriel wrobel, dr. kip andres, and dr. shawn morton, of the central belize archaeological survey, allowed me to work on the cbas project and collect these dental samples. michigan state university department of anthropology and the caves research foundation provided partial funding for sample preparation. the samples to be sent to spectrum petrographics. the institute of archaeology in belize provided permission for the histological analysis of these samples. literature cited antonova, a. 2011. growth, stress and mortality: application of dental histology to archaeological material from the cis-baikal neolithic. ma thesis, university of calgary. awe, j.j. 1998. the western belize regional cave project: a report of the 1997 field season. university of new hampshire, department of anthropology. bonor, jl. 2002. caves branch caves: archaeological field report. research report submitted to the foundation for the advancement of mesoamerican studies, crystal river. buikstra, j.e., ubelaker, d.h. 1994. standards for data collection from human skeletal remains. proceedings of a seminar at the field museum of natural history, vol. 68. arkansas archaeological survey. cook, d.c. 1981. mortality, age structure, and status in the interpretation of stress indicators in prehistoric skeletons: a dental example from the lower illinois river valley. in: chapman, r., kinnes, i., randsborg, k. (eds.), the archaeology of death (pp. 133-144). london: cambridge university press. cucina, a., tiesler, v. 2003. dental caries and antemortem tooth loss in the northern peten area, mexico: a biocultural perspective on social status differences among the classic maya. am j phys anthropol 122:1-10. danforth, m.e. 1989. a comparison of childhood health patterns in the late classic and colonial maya using enamel microdefects. phd dissertation, indiana university. danforth, m.e. 1997. late classic maya health patterns: evidence from enamel microdefects. in: whittington, s.l., reed, d.m. (eds.). bones of the maya (pp. 127-137). washington dc: smithsonian institution press. dunham, p.s., buchanan, j.p., meurer, w.p. 1998. the maya mountains archaeological project (mmap): report of the 1998 field season. fitzgerald, c.m., rose, j.c. 2000. reading between the lines: dental development and subadult age assessment using the microstructural growth markers of teeth. in: katzenberg, m.a., saunders, s.r. (eds.) biological anthropology of the human skeleton (pp. 237-263). john wiley and sons. fitzgerald, c.m., saunders, s.r. 2005. test of histological methods of determining chronology of accentuated striae in deciduous teeth. am j phys anthropol 127:277-290. gerry, j.p. 1997. bone isotope ratios and their bearing on elite privilege among the classic maya. geoarchaeology 12:41-69. glassman, d.m., villarejo bonor, j.l. 2005. mortuary practices of the prehistoric maya from caves 39 dental anthropology 2016 │ volume 29 │ issue 01 branch rockshelter, belize. in: prufer, k.m., brady, j.e. (eds.) stone houses and earth lords (pp. 285-296). boulder: university press of colorado. goldstein, d.j., prufer, k.m. 1999. report on rockshelter excavations at mayahek cab pek and mohibal kanchi, 1998 field season. in: dunham, p.s. (ed.) the maya mountains archaeological project (mmap): 1997 and 1998 archaeological excavations in the upper bladen drainage. goodman, a.h., rose, j.c. 1990. assessment of systemic physiological perturbations from dental enamel hypoplasias and associated histological structures. am j phys anthropol 33:59-110. gowland, r.l. 2015. entangled lives: implications of the developmental origins of health and disease hypothesis for bioarchaeology and the life course. am j phys anthropol 158:530-540. graham, e., mcnatt, l., gutehen, m.a. 1980. excavations in footprint cave, caves branch, belize. journal of field archaeology 7.2:153-172. hillson, s., antoine, d., dean, m.c. 1999. a detailed developmental study of the defects of dental enamel in a group of post-medieval children from london. in: mayhall, j.t., heikkinen, t. (eds.) proceedings of the 11th international symposium of dental morphology, august 26-30, 1998 (pp. 102-111). oulu, finland: oulu university press. hillson, s. 2014. tooth development in human evolution and bioarchaeology. cambridge: cambridge university press. marks, m.k. 1993. dental enamel microdefects as indicators of childhood morbidity among historic african americans. phd dissertation, the university of tennessee. michael, a.r., wrobel, g.d. 2011. a dental histological analysis of individuals interred in a variety of cave and rockshelter contexts in the caves branch river valley. paper at society for american archaeology annual meetings, sacramento, ca, march 30-april 3, 2011. michael, a.r., burbank, j.a. 2013. excavations at sapodilla rockshelter, caves branch river valley. the central belize archaeological project: a report of the 2011 field season. belize archaeologial research and education foundation occasional report #3. pp. 20-37. rose, j.c., armelagos, g.j., lallo, j.w. 1978. histological enamel indicator of childhood stress in prehistoric skeletal samples. am j phys anthropol 49:511-516. reents, d.j. 1980. the prehistoric pottery from petroglyph cave, caves branch river valley, el cayo district, belize, central america. unpublished ma thesis, department of anthropology, university of texas, austin. reeves, m.e. 2013. profiling metabolic stress in medieval denmark: an analysis of internal and external enamel defects. phd dissertation, the university of north carolina at chapel hill. saul, j.m., prufer, k.m, saul, f.p. 2005. nearer to the gods: rockshelter burials from the ek xux valley, belize. in: prufer, k.m., brady, j.e. (eds.). stone houses and earth lords: maya religion in the cave context (pp. 297-322). boulder, co: university of colorado press. scott, a.m., brady, j.e. 2005. human remains in lowland maya caves: problems of interpretation. in: prufer, k.m., brady, j.e. (eds.) stone houses and earth lords: maya religion in the cave context (pp. 263-284). boulder, co: university of colorado press. simpson, s.w. 1999. reconstructing patterns of growth disruption from enamel microstructure. in: hoppa, r.d., fitzgerald, c.m. (eds.) human growth in the past: studies from bones and teeth (pp. 241-263). cambridge university press. slon, b., michael, a.r. 2013. paper at the chacmool conference in calgary, alberta, canada, november 7-9, 2013. an analysis of dental defects in cave and rockshelter populations, central belize. storey, r. 1997. individual frailty, children of privilege, and stress in late classic copan. in: whittington, s.l., reed, d.m. (eds.) bones of the maya (pp. 116-126). washington dc: smithsonian institution press. temple, d.h., goodman, a.h. 2014. bioarchaeology has a “health” problem: conceptualizing “stress” and “health” in bioarchaeological research. am j phys anthropol 155:186-191. thomson, c.c. 2011. dental microstructures and maturation: a case study of stress during growth and development. ma thesis, trent university. white, c.d. 1997. ancient diet at lamanai and pacbitun: implications for the ecological model of collapse. in: whittington, s.l., reed, d.m. (eds.) bones of the maya (pp. 171-180). washington dc: smithsonian institution press. white, c.d. (2005). gendered food behaviour among the maya: time, place, status, and ritual. journal of social archaeology 5:356-382. witzel, c., kierdorf, u., schultz, m., kierdorf, h. 2008. insights from the inside: histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth. am j phys anthropol 136:400-414. wright, l.e. 1990. stresses of conquest: a study of wilson bands and enamel hypoplasias in the maya of lamanai, belize. am j hum biol 2:25-35. wright, l.e. 1997. intertooth patterns of hypoplasia 40 dental anthropology 2016 │ volume 29 │ issue 01 expression: implications for childhood health in the classic maya collapse. am j phys anthropol 102:233-247. wright, l.e. 2006. diet, health, and status among the pasion maya: a reappraisal of the collapse. vanderbilt institute of mesoamerican archaeology, volume 2. nashville, tn: vanderbilt university press. wrobel, g.d., tyler, j., hardy, j. 2007. rockshelter excavations in the caves branch river valley. research reports in belizean archaeology 4:187196. wrobel, g.d. 2008. report on the caves branch rockshelter excavations 2006 and 2007 field seasons. belize valley reconnaissance project field report. wrobel, g.d., jordan, j.m., hardy, j. 2009. social and political transformations in the caves branch river valley: evidence from natural and constructed ritual environments. research reports in belizean archaeology 6:199-207. mcgettigan et al. 2011.1 tooth formation is a developmental process that is thought to be less influenced by environmental insults than other markers of development and is thus regarded to be an accurate method for estimating chronological age (demirjian et al., 1985). a substantial body of research by the same author into the timing of development of the dentition has focused on well-described stages applied to large samples (demirjian et al., 1973; demirjian and goldstein, 1976; demirjian and levesque, 1980; demirjian, 1994). our earlier research into dental ageing of new zealand populations used demirjian’s method to record standards for dental development in european, pacific island and maori children (kieser et al.,2008; temoananui et al., 2008a, 2008b). more recently, we contrasted the use of demirjian’s method with that of cameriere and coworkers (2006). while we found that both the methods reliably predicted chronological age in children aged 7-17 years, a disadvantage of using the cameriere method was that all seven teeth reached maturity at 13.69 and 14.06 years in females and males, respectively, compared to age 16 using demirjian (timmins et al., 2011). because neither method predicted age beyond 16 years, we decided to evaluate the usefulness of the demirjian method when applied to third molar development in the same population sample. materials and methods we sourced a total of 207 panoramic radiographs of children aged between 7 years, 6 months and 18 years from various orthodontic clinics throughout new zealand, described previously (timmins et al., 2011). photographic images of the radiographs were captured using a canon ixus 870is 10 mega-pixel camera with a 28 mm wide-angle lens and optical image stabilizer. the sex distribution of our sample was 105 males to 102 females. there were 20 participants (10 male and 10 female) in each age category up to age 17, but in the category for age 18 there were two females and five males. some radiographs had to be excluded because the wisdom tooth of interest had been cropped out of the picture, the radiographic quality was too poor to adequately score the tooth, or the wisdom tooth had not yet started to develop and it was deemed to be congenitally missing. if the second molar displays parallel root canal spaces and the apex is half closed (converging root canal apices) or fully closed, then wisdom tooth formation as a method of estimating age in a new zealand population annabelle mcgettigan1, kimberley timmins1, peter herbison2, helen liversidge3 and jules kieser1* 1sir john walsh research institute, faculty of dentistry, university of otago, dunedin, new zealand 2department of preventive and social medicine, dunedin school of medicine, university of otago, dunedin, new zealand 3department of paediatric medicine, queen mary university of london, london e1 2ad, united kingdom *corresponding author: jules kieser, sir john walsh research institute, faculty of dentistry, university of otago, dunedin 9054 new zealand email: jules.kieser@otago.ac.nz abstract dental ageing relies on assumptions about the progression of tooth development from the middle trimester to adulthood and relative stability of this process in the face of adverse dietary, hormonal, disease or nutritional factors. most studies of dental ageing employ the method of demirjian et al., (1973), which is based upon an assessment of crown and root formation stages from dental radiographs. unfortunately, this method has a ceiling effect at age 16, when the second molar attains full maturity. the aim of our study was to extend the window of ageing by using the development of the third molar teeth. panoramic radiographs of 207 (105 males) children aged between 7 years, 6 months and 18 years formed the basis of this study. upper and lower left wisdom teeth were scored according to demirjian et al. (1973) by a single examiner. intra-examiner reliability was evaluated by repeat scoring of a randomly selected (10%) sample one week after the initial staging. these showed a consistency of 76% for the mandibular data and 95% for the maxillary data, giving an overall percentage of 85%. when the re-scored teeth were not consistent with their original score, this differed only by one stage. in this population males were advanced in their third molar development and this trend was more marked for maxillary than mandibular wisdom teeth. hence, the new zealand population examined, males were more advanced in their third molar development and this trend was more marked for maxillary than mandibular teeth. dental anthropology 2011;24(2):33-41. 34 table 2. maxillary staging by chronological year of age stage 8 9 10 11 12 13 14 15 16 17 18 total size size: 15 15 6 4 6 2 1 49 a 2 1 3 6 b 2 4 5 1 4 3 1 19 c 3 6 5 3 6 2 1 2 28 d 1 5 3 10 7 8 6 5 45 e 1 1 1 5 6 2 16 f 4 4 1 9 g 3 4 7 h 1 1 total 19 20 18 16 19 19 19 18 18 20 7 180 it is highly likely the third molar is congenitally missing and will not develop. if the second molar is less mature than this, then it is still possible that the third molar might develop. armed with this knowledge we were able to exclude those whose wisdom teeth were congenitally missing from our data set. after all exclusions, we were left with 193 radiographs for the lower left wisdom teeth and 180 radiographs for the upper left wisdom teeth, a full breakdown of the age and sex distribution of our final sample can be found in table 1. the upper and lower left wisdom tooth was scored according to a modified version of demirjian et al. (1973) for staging the formation of the dentition, as illustrated in figure 1. a single examiner evaluated both the upper and lower left wisdom teeth according to these criteria using a standard zoom facility with contrast enhancement. when we were unable to score the wisdom tooth of interest because the photograph had been cropped, the antimere was scored instead when visible. we examined intra-examiner reliability by repeating the scoring for a randomly selected 10% of the sample one week after the initial staging. for statistical analysis of the data set, age for each individual was recorded to two decimal places to allow for more accurate analysis of the correlation between chronological and dental age. the prediction of age from maturity status was done using polynomial regression with linear, quadratic and cubic terms. this required the assumption that the maturity stages are equally spaced. 0 crypt outline visible, no calcification. a calcification seen, no fusion of points. b fusion of calcified points. c enamel formation complete, crown ½ formed,pulp chamber curved. d crown formation is complete, pulp chamber is trapezoidal, root formation commenced. e radicular bifurcation observed; root length less than crown height. f root endings flared; root length at least equal to crown height. g root canal walls parallel, apices open. h apex closed, uniform periodontal space. results intra-observer validity tests showed a consistency of 76% for the mandibular data and 95% for the maxillary data, giving an overall percentage of 85%. when the rescored teeth were not consistent with their original score, this differed only by one stage. in this population, it appears that males are advanced in their third molar development as can be seen by the mean age of each developmental stage, this is more marked for maxillary wisdom teeth than mandibular wisdom teeth. after age 15, no stage lower than stage “c” was observed for both mandibular and maxillary wisdom teeth and thus it can be hypothesized that in this population the presence of wisdom teeth at stage b or lower is indicative of age <15 (tables 2, 3). stage “f” was observed in only one individual below the age of 16, thus if stage “f” is observed in an individual, it is highly likely that the individual is 16 years or older. a considerable amount of disagreement existed between the staging of the mandibular wisdom tooth and the staging of the maxillary wisdom tooth and this disagreement was statistically significant (table 4). figures 2 and 3 show actual age of male and female participants as a function of the developmental scores for mandibular and maxillary wisdom teeth respectively. confidence intervals (95%) are given by the dotted lines. it is clear that females develop faster than males. figures 4 and 5 show box-and-whisker plots of demirjian’s dental stages as well and chronological ages for mandibular and maxillary teeth in males and females. outliers are depicted as small circles. again, it is evident that boys a. mcgettigan et al. 35 0 outline visible, no calcification. a calcification seen, no fusion of points. b fusion of calcified points. c enamel formation complete, crown ½ formed, pulp chamber curved. d crown formation is complete, pulp chamber is trapezoidal, root formation commenced. e radicular bifurcation observed; root length < crown height. f root endings flared; root length >= crown height. g root canal walls parallel, apices open h apex closed, uniform periodontal space. fig. 1. modified staging method based on demirjian et al. (1973). wisdom tooth formation 36 develop later than girls. discussion from these data, new zealand population-specific prediction charts were developed to aid estimation of chronological age from wisdom tooth stage as shown in figures 4 and 5. normal development charts were also generated to aid orthodontic treatment planning to determine whether an individual’s development is normal, advanced or delayed (figs. 2 and 3). it must be noted, however, that these charts assume there is an equal distance between each of the stages; that is, the time difference between a and b is the same as the difference between d and e. it is highly likely that this is not the case, and these stages may in fact be staggered with one lasting only a few months and others maybe lasting a few years. hägg and matsson (1985) observed that earlier stages of tooth formation were generally of shorter duration than later stages with regard to teeth 41 through to 47 (fdi scoring system), and this is likely to be the case also with regard to the third molar. gunst et al. (2003) set out to calculate the chronological age of belgian caucasian individuals based on the development of the third molars using a 10-stage developmental scoring method proposed by kohler and co-workers (1994). they found a slight sexual dimorphism with relation to timing of the stages (males had a younger mean age for each stage), and a trend for earlier development in maxillary third molars compared to mandibular. generally, however, the relationship between chronological age and dental age of the third molars has been investigated using variations of demirjian’s stages. in 2004, arany et al. used demirjian’s stages to estimate the probability of a japanese adolescent being over the ages of 14, 16 and 20 (the relevant ages as determined by japanese juvenile law). this study found table 3. mandibular staging by chronological year of age stage 8 9 10 11 12 13 14 15 16 17 18 total sample size: 15 9 6 4 5 1 6 46 o 1 2 3 2 1 9 a 4 7 1 2 2 1 1 18 b 2 7 5 6 1 21 c 2 5 2 12 5 6 4 1 1 38 d 2 3 5 4 7 5 4 30 e 1 3 5 5 5 3 22 f 1 1 2 1 5 g 1 2 1 4 h 0 total 20 20 19 20 20 20 20 18 16 14 6 193 table 4. mandibular versus maxillary staging maxillary stage grade o a b c d e f g h total o 0 5 0 0 1 0 0 0 0 6 a 0 1 7 0 2 0 0 0 0 10 b 0 0 6 8 3 0 0 0 0 17 c 0 0 4 12 18 0 0 0 0 34 d 0 0 0 4 14 4 2 0 0 24 e 0 0 0 0 3 8 3 4 0 18 f 0 0 0 0 1 2 1 1 0 5 g 0 0 0 0 0 0 2 1 1 4 h 0 0 0 0 0 0 0 0 0 0 total 0 6 17 24 42 14 8 6 1 118 χ² df p-value symmetry (asymptotic) 34.25 13 0.0011 m an d ib ul ar s ta ge a. mcgettigan et al. 37 that recognition of earlier stages (a-d) in an individual indicate that person is <20 years old. while the presence of stage f indicates it is highly likely the individual is over 14, and if stage h has been reached then it is almost certain that the person is >16 (arany et al., 2004). prieto et al. (2005) used demirjian’s stages to investigate the relationship between chronological age and dental age of the third molars in a spanish population. they used a sample between the ages of 14 and 21 years of age, and as they at no time observed a stage lower than c, it may be assumed that observation of stage a or b would indicate an individual is <14 years in this population. they also investigated the probability of an individual being > or < 18 years based on third molar development. stage d-e indicated a high probability a person was <18, stage f indicated it is likely the individual is <18, stage g was about 50/50, and stage h indicated a high probability the individual was ≤ 18 (prieto et al., 2005). orhan et al. (2007) used demirjian’s classifications to determine the relationship between developmental stages of third molars and chronologic age in a turkish population sample for the purpose of age estimation. the relationship between third molar development and sex, age and location was also investigated. they found no statistically significant difference between left and right third molars but they did find that maxillary third molar development was commonly more advanced than mandibular third molar development, which is consistent with the findings from gunst et al. (2003). males showed advanced third molar development compared to females which is also consistent with other studies (gunst et al., 2003; arany et al., 2004; prieto et al., 2005). in accordance with the above-mentioned study (prieto et al., 2005) this study found that stage d-e indicated an individual was <18, and stage h indicated an individual was >18. knell et al. (2009) used only lower wisdom teeth to determine chronological age and found there was an 85% agreement on stages between left and right sides of the jaw. of the 15% that were not the same on both sides of the jaw, the majority differed only by one stage. however, it was found that stage h was attained at ages less than 18 in some cases, so the above statement that attainment of stage h indicates the individual is over 18 may not hold true for all situations in all populations. third molar development has also been used to estimate chronological age in a portuguese population (caldas et al., 2010). in this study the probability of an individual being at least 16 years was investigated. it fig. 2. prediction of chronological age from mandibular third molar stage wisdom tooth formation 38 was found that while sexual dimorphism was not always present for every stage of third molar development; overall, third molar formation occurred earlier in boys, which is in agreement with gunst et al. (2003). it was suggested that presence of stage d was perhaps the earliest indicator of an individual being over 16 years of age. as has been discussed already, after the age of around 14 it becomes increasingly more difficult to determine age as there are fewer teeth undergoing development. there is some controversy in the literature about whether we should be using third molars for age estimation in this age group or whether we should be using skeletal development of the hands and wrists (demisch and wartmann, 1956; engström et al., 1983). a linear relationship between chronological age, skeletal development and third molar formation has been observed (demisch and wartmann, 1956). while the correlation between chronological age and third molar development and the correlation between chronological age and skeletal development are comparable (engström et al., 1983); third molars have the advantage of developing for longer and may be the only developmental marker available in late adolesence (mesotten et al., 2002). it appears that the new zealand population does not differ significantly in third molar development compared with other populations, as similar trends were found in this study as in other studies on different populations. a slight sexual dimorphism was found with males tending to develop earlier than females, probably because of post-pubertal development of this tooth. this trend was also documented in previous studies (gunst et al., 2003; caldas et al., 2010; orhan et al., 2007; arany et al., 2004; prieto et al., 2005; harris, 2007; sisman et al., 2007). additionally, gunst et al. (2003) reported earlier development in maxillary, compared to mandibular third molars, which is mirrored in the present study. it has been quoted in the literature that the presence of stage f is indicative of an individual being over the age of 14 (arany et al., 2004). this trend can also be observed in our new zealand sample. however, in our sample some individuals who were 18 presented with stage e or lower, which was not found in some other literature (prieto et al., 2005). attainment of stage h indicating an individual is over the age of 18 was found in the present study and in others (prieto et al., 2005; orhan et al., 2007; knell et al., fig. 3. prediction of chronological age from maxillary third molar stage. a. mcgettigan et al. 39 2009). the principal aim of our study was to evaluate the usefulness of the demirjian method when applied to third molar development in a sample of new zealand children. although we have previously studied dental maturation and cervical vertebral development in three different ethnic groups from new zealand (european, maori and pacific island, temoananui et al., 2008a,b), the present investigation focused on an older age group and made no attempt at recording ancestry. our focus was on adolescence, a time of major hormonal, growth and secondary sexual changes (bogin, 2001), rather than on ethnicity. we conclude that while chronological age can indeed be estimated from third molar development, the age range can be relatively broad for given developmental stages. literature cited arany s, iino m, yoshioka n. 2004. radiographic survey of third molar development in relation to chronological age among japanese juveniles. j forensic sci 49:1-5. bogin b. 2001. the growth of humanity. new york: wiley liss. caldas im, julio p, simoes rj, matos e, afonso a, magalhaes t. 2010. chronological age estimation based on third molar development in a portugese population. int j legal med 125:235-243. cameriere r, ferrante l, cingolani m. 2006. age estimation in children by measurement of open apices in teeth. int j legal med 120: 49-52. demirjian a, buschang ph, tanguay r, kingnorth patterson d. 1985. interrelationships among measures of somatic, skeletal, dental, and sexual maturity. am j orthodont 88:433-438. demirjian a, goldstein h. 1976. new systems for dental maturity based on seven and four teeth. ann hum biol 3:411-427. demirjian a, goldstein h, tanner jm. 1973. a new system of dental age assessment. hum biol 45:211-227. demirjian a, levesque gy. 1980. sexual differences in dental development and prediction of emergence. j fig. 4. prediction of chronological age from mandibular third molar stage wisdom tooth formation 40 dent res 59:1110-1122. demisch a, wartmann p. 1956. calcification of the mandibular third molar and its relation to skeletal and chronological age in children. child dev 27:459-473. engström c, engström h, sagne s. 1983. lower third molar development in relation to skeletal maturity and chronological age. angle orthod 53: 97-106. gunst k, mesotten k, carbonez a, willems g. 2003. third molar root development in relation to chronological age: a large sample sized retrospective study. forensic sci int 136:52-57. hägg u, matsson l. 1985. dental maturity as an indicator of chronological age: the accuracy and precision of three methods. eur j orthodont 7:25-34. harris ef. 2007. mineralization of the mandibular third molar: a study of american blacks and whites. am j phys anthropol 132:98-109. kieser ja, defeijter j, temoananui r. 2008. automated dental aging for child victims of disasters. am j disaster med 3:109-112 knell b, ruhstaller p, prieels f, schmeling a. 2009. dental age diagnostics by means of radiographical evaluation of the growth stages of lower wisdom teeth. int j legal med 129:465-469. kullman l. 1995. accuracy of two dental and one skeletal age estimation method in swedish adolescents. forensic sci int 75:225-236. lewis ab, garn sm. 1959. the relationship between tooth 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wisdom tooth mineralization. int j legal med 118:170173. orhan k, ozer l, orhan ai, dogan s, paksoy cs. 2007. radiographic evaluation of third molar development in relation to chronological age among turkish children and youth. forensic sci int 165:46-51. prieto jl, barberia e, ortega r, magana c. 2005. evaluation of chronological age based on third molar development in the spanish population. int j legal med 119:349-354. ritz-timme s, cattaneo c, collins mj, waite er, schutz hw, kaatsch hj, borrman him. 2000. age estimation: the state of the art in relation to the specific demands of forensic practise. int j legal med 113:129-136. saunders s, devito c, herring a, southern r, hoppa r. 1993. accuracy tests of tooth formation age estimations for human skeletal remains. am j phys anthropol 92:173-188. staaf v, mornstad h, welander u. 1991. age estimation based on tooth development: a test of reliability and validity. scand j dent res 99:281-286. sisman y, uysal t, yagmur f, ramoglu si, 2007. thirdmolar development in relation to chronologic age in turkish children and young adults. angle orthod 77:1040-1045. temoananui r, kieser ja, herbison gp, liversidge hm. 2008a. estimating age in maori, pacific island and european children from new zealand. j forensic sci 53:401-404. temoananui r, kieser ja, herbison gp, liversidge hm. 2008b. advanced dental maturation in new zealand maori and pacific island children. am j hum biol 20:43-50. timmins k, herbison p, farella m, liversidge h, kieser ja. 2011 the usefulness of dental and cervical maturation stages in new zealand children for disaster victim identification. for sci med pathol (in press). willems g, van olmen a, spiessens b, carels c. 2001. dental age estimation in belgian children: demirjians technique revisited. j forensic sci 46:893-895. wisdom tooth formation szabo et al. 2009.3 18 supernumerary teeth are those that are additional to the normal complement (schulze, 1987). they may occur in any region of the dental arch with a particular predilection for the premaxilla (primosch, 1981; nasif et al., 1983). this location is followed in decreasing order of frequency by fourth molars or upper distal molars, maxillary paramolars and by lower premolars, upper lateral incisors, lower fourth molars, and lower central incisors. upper premolars are exceptional, as are upper and lower canines and lower lateral incisors (gay et al., 1999). supernumerary teeth have been reported in both the primary and the permanent dentitions. cases involving one or two supernumerary teeth most commonly involve the anterior maxilla (stafne, 1932), followed by the mandibular premolar region (nasif et al., 1983; stafne, 1932). the etiology of supernumerary teeth is still not clearly understood, but several theories have been suggested for their occurrence (rajab and hamdan, 2002). for developmental biologists, the phenomenon of supernumerary teeth raises interesting questions about the development and fate of the dental lamina. also, the supernumerary teeth inspire questions about the actions and interactions of transcription factors and growth factors that coordinate morphogenesis, cell survival and programmed cell death. for clinicians faced with treating the dental complications that arise from the presence of supernumerary teeth, knowledge about the abstract supernumerary teeth are those that are additional to the normal complement. they may occur in any region of the dental arch and have been reported in both the primary and the permanent dentitions. the etiology of supernumerary teeth is still not clearly understood, but several theories have been suggested for their occurrence. the investigated material were the remains from the bácsalmás-óalmás burial site (from the 16th-17th centuries), where 472 skeletons were excavated from 1993 to 2003. for the purpose of this study, the dentitions of 164 adult individuals were examined. the examination was carried out using macromorphological methods, radiographic analysis and a dial caliper were applied. this paper describes a supernumerary tooth of an adult female skeleton. on the labial surface of the first mandibular premolar an extra tooth was observed. radiographic examination of the fused teeth indicated that the crown of the premolar had fused incompletely with the crown of the extra tooth. the position of the extra tooth could have been the result of gemination of the tooth germ or the elaboration of the buccal cingulum. the cranium of the examined individual showed some mongoloid morphologic features, too. our presumption about the formation of the supernumerary tooth may have contributed to the theories of the occurrence of supernumeraries. the sporadic occurrence of this anomaly was reported in recent and archaeological skeletal collections. this study showed that multiple permanent dental formation was present in past hungarian populations, representing a contribution to the history of dental anomalies. dental anthropology 2009;22(1):19-22. joined supernumerary mandibular teeth in the premolar region: report of a hungarian archeological case gy. szabó*, g. kocsis s., e. molnár university of szeged, department of anthropology, szeged – hungary, h-6701 basic mechanisms involved is essential. heredity may be a relevant etiological factor in the occurrence of supernumerary teeth (rajab and hamdan, 2002). supernumeraries are more common in the relatives of affected children than in the general population (garvey et al., 1999). the reported prevalence of supernumeraries in the general caucasian population for the permanent dentition ranges from 0.1 to 3.8% (rajab and hamdan, 2002). supernumerary teeth seem to be more common in asian populations, with a frequency higher than 3% being reported (davis, 1987). sexual dimorphism has been reported by most authors (hurlen and humerfelt, 1985; mitchell, 1989) with males being affected more commonly. the occurrence of this anomaly is also reported in archeological skeletal collections. hillebrand (1908) found 14 supernumerary teeth during the paleostomatological investigation of 4,100 skulls. schwerz (1916) described this anomaly in two out of 510 cases. the sporadic occurrence of supernumeraries in past populations was reported in several other studies correspondence to: gyöngyi szabó, h-6701 szeged, p.o. box 660, hungary e-mail: szabo.gyongi@hotmail.com 19 collected by kocsis (1993). this report describes a rare developmental anomaly of a mandibular tooth of a young adult (25-30 yrs) female. materials and methods the material for this report was the skeletal population of bácsalmás-óalmás burial site found in a sand pit, where 472 skeletons were excavated from 1993 to 2003. on the basis of the archeological and historical data, this group immigrated from the balkan peninsula to the southern part of hungary in the sixteenth century. for the purpose of this study, the dentitions of 164 wellpreserved adult individuals (76 males, 75 females, 13 indeterminate) were examined. altogether 2,693 teeth (with the exception of the third molars) were used for the investigation. the examination was carried out using macromorphological methods and radiographic analysis. a dial caliper was used for the metric analysis. results during the paleostomatological investigation, altered number of teeth was one of the examined anomalies. the present report is a case of hyperdontia. the lower left first premolar of the young adult female revealed double tooth formation. only this one case of hyperdontia was found from among the 164 skulls in the skeletal series of bácsalmás-óalmás. due to postmortem loss, the young adult female had no upper left incisors and the upper right central incisor was missing. pitted hypoplasia on the incisors was seen. mild periodontal atrophy was fig. 3. mesiodistal radiographic image of the double tooth formation. lingual is to the right. fig. 2. distal view of the double tooth formation. lingual is to the right. fig. 1. joined supernumerary tooth in the left premolar region of mandible. joined premolar teeth 20 evident on the whole dental arch. on the labial surface of the mandibular first premolar, there is a supernumerary tooth, where the size was definitely smaller than the premolar (fig. 1, 2). the double tooth displays a bifid crown with a welldefined groove that extends to the distal third of the root. the crown height was 3.64 mm, while that of the premolar-proper was 8.14 mm. the greatest mesiodistal dimension of the accessory crown was 3.22 mm and 7.28 mm for the first premolar. root length was 10.62 mm and 14.32 mm for the premolar. no anomaly was observed in the right mandibular quadrant, so this represents a unilateral event. the cranium showed some mongoloid morphologic features, such as shallow canine fossa and shovel shaped upper incisors. the skeletal remains were well preserved. all of the teeth were found with the exception for the upper left canine, the upper left third molar and the upper right third molar. the status of their alveoli indicates postmortem loss. different stages of dental caries occurred on the occlusal and mesial surfaces of molars. caries superficialis were the most common, but a single case of caries penetrans was also observed, on the upper right first molar. discussion supernumerary teeth may occur singly or in multiples in any region of the jaws in the same person. this study describes a unilateral supernumerary mandibular tooth of an adult female skeleton. radiographic examination of the fused teeth indicated that the crown of the normal premolar had fused incompletely with the crown of the extra tooth. the fused teeth have two root canals and two partly separate roots. communication between the pulp chambers of the teeth could be detected radiographically. the position of the extra tooth can be the result of gemination of the first premolar, which means that two morphological units were created by division of the tooth germ. the result is the incomplete formation of two teeth. according to pindborg (1970), a true concretion develops during the formation of teeth and it is caused by the lack of space. but from another perspective the extra tooth can be the elaboration of the buccal cingulum of the premolar. in support of this concept, the crown is not fused completely and the roots are separated. regarding the etiology of this dental anomaly, rajab and hamdan (2002) considered heredity as an important etiological factor in the occurrence of supernumerary teeth. heredity is not conclusive as no other supernumerary was found in this skeletal collection (164 skulls). the fact that supernumerary teeth are more common in mongoloid racial groups seems to be conclusive in this case because the investigated skull also shows mongoloid characteristics. clinical complications related to double teeth include caries along the grooves dividing each other and periodontal atrophy, esthetics, and malocclusion (silva and silva, 2007). in extant groups, the majority of such teeth are asymptomatic, so endodontic treatment is unnecessary in most cases (cetinbas et al., 2007). the sporadic occurrence of supernumerary teeth is reported in recent (hassan et al., 2006) and archeological (sutton, 1985; smith, 2004) skeletal collections. kocsis (1993) investigated the permanent frontal teeth of 1,997 individuals originating from different archeological periods of hungary. he found 23 supernumeraries with a highest frequency in the 10th century ad. this case report shows that permanent dental formations in the premolar region were also present in the past populations of hungary, representing a contribution to the history of dental anomalies. literature cited cetinbas t, halil s, akcam mo, sari s, cetiner s. 2007. hemisection of a fused tooth. oral surg oral med oral path oral radiol endod 104:120-124 davis pj. 1987. hypodontia and hyperdontia of permanent teeth in hong kong school children. community dent oral epidemiol 15:218-220. d’souza rn, klein od. 2007. unraveling the molecular mechanisms that lead to supernumerary teeth in mice and men: current concepts and novel approaches. cells tissues organs 186:60-69. garvey mt, berry hj, blake m. 1999. supernumerary teeth—an overview of classification, diagnosis and management. j can dent assoc 61:612-616 gay c, mateos m, españa a, gargallo j. 1999. otras inclusiones dentarias: mesiodens y otros dientes supernumerarios. dientes temporales incluidos. in: gay c, berini l, editors. cirugía bucal. madrid: editorial ergon, madrid. p 511-550. hillebrand j. 1908. újabb adatok az ember fogainak alaktanához. budapest: stephaneum. hurlen b, humerfelt d. 1985. characteristics of premaxillary hyperodontia: a radiographic study. acta odontol scand 43:75-81. kocsis sg. 1993. investigation of macromorphological developmental anomalies of permanent front teeth from different archaeological periods of hungary. thesis, jate, department of anthropology, szeged [in hungarian]. mitchell l. 1989. supernumerary teeth. dent update 16:65-69. nasif mm, ruffalo rc, zullo t. 1983. impacted supernumerary teeth: a survey of 50 cases. j amer dent assoc 106:201-204. pindborg jj. 1970. pathology of the dental hard tissues. san francisco: wb saunders company. primosch r. 1981 anterior supernumerary teeth-assessment and surgical intervention in children. pediatr g. szabo´ et al. 21 dent 3:204-215. rajab ld, hamdan mam. 2002. supernumerary teeth: review of the literature and survey of 152 cases. int peadiatr dent 12:244-254. schulze ch. 1987. anomalien und mißbildungen der menschlichen zähne. quintessenz vol 94-101. schwerz f. 1916. morphologische untersuchungen an zähnen von alamannen aus dem v. bis x. jahrhundert. arch anthropol 15:1-43. silva am, silva al. 2007. unilateral fusion of two primary mandibular teeth: report of a portuguese archeological case. dental anthropology 20:16-18. the case report by gyongyi szabó and colleagues (dental anthropology 2009;22(1):18-21) raises several interesting issues. a challenging aspect of examining teeth—which are the end-products of foregone cascades of developmental events—is that interpretations of the formative processes that produced the final form are conjectural, and there is no way to test assumptions. experience and encountering repeated occurrences of a dental condition are helpful, but they are hardly infallible. terminology a fundamental consideration raised by this case report is terminology. specifically, what constitutes a supernumerary tooth? or, for that matter, what is a tooth? i looked through a number of recent papers on hypoand hyperdontia, and there is a striking absence of an operational definition of what a “tooth” is. recognition of a tooth evidently is considered so obvious (or so difficult) that it doesn’t warrant a definition. it seems that mineralized tissues (dentin, enamel) are an important criterion, but this is simply because most studies nowadays are radiographic surveys, so premineralized tissues are undetectable. however, dental histologists are quite comfortable that the premineralized structures seen in the bud, cap, and bell stages constitute a “tooth,” so mineralization cannot be an essential feature. popular textbooks on dental anatomy (e.g., zeisz and nuckolls, 1949; kraus et al., 1969; ash, 1993) launch right into descriptions of the morphology of each tooth type, apparently supposing that a definition would be superfluous. the normally-occurring teeth (20 primary, 32 permanent) are all characterized by a *correspondence to: edward f. harris, department of orthodontics, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu smith p. 2004. middle bronze age ii burials at sasa, upper galilee (tomb 1 and graves 37, 39). ’atiqut 46:35-43. stafne ec. 1932. supernumerary teeth. dental cosmos 74:653-659. sutton pr. 1985. tooth eruption and migration theories: can they account for the presence of a 13,000-yearold mesiodens in the vault of the palate? oral surg oral med oral path oral radiol endod 59:252-255. commentary: supernumerary teeth edward f. harris department of orthodontics and department of pediatric dentistry, university of tennessee, memphis fig. 4. a supernumerary tooth in the enlarged incisive foramen of a prehistoric american indian. ectopic teeth tend to be in the vicinity of the dental arches, but they may form or migrate elsewhere. joined premolar teeth crown (enamel, dentin, pulp) and one or more roots (cementum, dentin, pulp), but it is not clear whether a dental element must have all of these features to achieve “toothness.” also, sizes of the crown and root do not seem to be important criteria. one might claim that teeth obviously are found in the two dental arches, but locality is not definitive given the extraordinary hardin and legge 2013.2 5 2011 dahlberg award winner: evaluation of the utility of deciduous molar morphological variation in great ape phylogenetic analysis anna m. hardin 1,2 and scott s. legge 1 1 macalester college, st paul, minnesota, 55105 2 university of minnesota, minneapolis, minnesota, 55455 the teeth of the great apes bear an uncanny resemblance to those of humans in terms of their overall morphology. while the permanent teeth of humans and great apes have been studied in depth for several decades, deciduous teeth are often overlooked. unlike permanent teeth, which are often used in both metric and non-metric studies to trace genetic drift and population variation, deciduous teeth are rarely studied in detail or in large numbers in either humans or primates. since non-metric traits in adult primates have been used in many important studies they can serve as an example for work that can be done with deciduous primate teeth. several studies offer trait frequency data for non-metric traits in great ape adult dentitions (e.g., bailey 2008, swindler 2005, swarts 1988) and swindler (2005) provides some description of the morphology of great ape deciduous teeth. human deciduous dental morphology has been described by jorgensen (1956) and scott and turner (1997). the present study addresses the dearth of information on great ape deciduous dentitions by looking at the variation in tooth crown morphology of subadult chimpanzees and gorillas. previous research on non-metric traits among humans has revealed that they are useful in assessing population relatedness as well as population movements through time (e.g. scott and turner, 1997; irish, 2006; hanihara, 2008), and analysis of the deciduous dentition of the great apes may allow for similar assessments. in this study, variations in frequencies and patterns of occurrence for 28 dental traits are examined in five great ape subspecies. the utility of the deciduous dentition is assessed in addressing questions of population affinity and contributing to a set of standards and traits that can be used in further studies. materials data were collected on the postcanine deciduous teeth from detailed photographs of 179 juvenile great ape dental arcades. the specimens belong to the collections of the quex museum of birchington, uk and the royal museum of central africa in tervuren, belgium. five of the gorillas came from the collection at the university of minnesota department of anthropology. the samples included specimens identified in the museum catalogs as pan troglodytes troglodytes, pan troglodytes schweinfurthii, pan paniscus, gorilla gorilla gorilla, and gorilla beringei graueri (table 1). abstract non-metric dental traits are wellestablished tools for anthropologists investigating population affiliation and movement in humans. nonetheless, similar traits in the great apes have received considerably less attention. the present study provides data on non-metric trait variability in the deciduous molars of great apes from museum context.twenty-eight traits are observed in the upper and lower deciduous molars in specimens of pan troglodytes, pan paniscus, gorilla gorilla, and gorilla beringei. these groups are compared based on trait frequencies and mean measures of divergence. this study demonstrates the variability of non-metric traits in the deciduous molars of chimpanzees and gorillas. these traits could potentially be used in the same way that non-metric traits are in humans, namely group affiliation and population movements through time. further, this study establishes scoring guidelines and methodology relevant to deciduous dental morphological characteristics found in the great apes, but not necessarily in humans. correspondence to: anna hardin university of minnesota, department of anthropology 395 humphrey center, 301 19th ave s. minneapolis, mn 55455 hardi227@umn.edu 319-321-7104 keywords: primate deciduous dentition, non-metric dental traits, pan, gorilla 6 methods traits upper deciduous molars. nine traits were observed in the upper deciduous molars. the transverse crest in the upper first deciduous molar (udp3) is an enamel ridge connecting the paracone and protocone (swindler, 2005). it has been variously labeled the central ridge (jørgensen, 1956) and the oblique ridge (kraus et al. 1969) in human deciduous teeth. for the present study it was scored according to a previously used scale from 0 to 3 (bailey, 2002). although this scoring was originally for lower adult premolars, it describes the variation in udp3 well. the lingual cingulum of the two upper deciduous molars (udp3 and udp4) was scored from 0 to 3 (figure 1). the scores are based on swindler’s observation that the lingual cingulum in gorilla and pan differed in that, “a lingual cingulum is present in gorilla extending mesially from the hypocone to the mesial surface of the protocone. a cingulum is present in pan only on the lingual surface of the protocone.” (swindler, 2005). due to these distinctions, this trait was scored as absent (0), a raised surface of the lingual side of the protocone (1), an enamel ridge on the lingual side of the protocone (2), or an enamel ridge extending from the protocone to the hypocone (3). on udp3 there is no hypocone, so the scoring of 3 is reserved for a lingual cingulum that extends across the entire lingual surface of the protocone. it is important to note that the smallest lingual cingulum is not considered to be a small carabelli’s trait because these two structures likely derive from separate features (ortiz et al. , 2010). the buccal cingulum on udp3 and udp4 is scored only as present or absent where presence is considered to be any expression of a cingulum on the buccal surface of the tooth (figure 2). none of the sources that were used mentioned a buccal cingulum on the great ape upper deciduous dentition, although it is observed in the great apes on lower deciduous molars and upper permanent molars (swindler, 2005). the crista obliqua is a ridge connecting the protocone and metacone of udp4 (swindler, 2005). it has also been referred to as the postprotocrista (swarts, 1988). it was recorded as absent (0), interrupted (1) or uninterrupted (2). also on udp4, cusp 5 was scored from 0 to 5 following the arizona state university dental anthropology system (asudas) for cusp 5 on um1 (turner et al. 1991). finally, the anterior and posterior foveae on udp4 were scored as either present or absent. in the asudas, the anterior fovea is scored based on its size, but the present study found that on deciduous teeth both anterior and posterior foveae were generally too small to vary noticeably. any species number of individuals number of teeth pan troglodytes 99 665 p. t. troglodytes 39 270 p. t. schweinfurthii 60 395 pan paniscus 48 329 gorilla gorilla gorilla 28 194 gorilla beringei graueri 11 81 table 1. number of individuals studied in each african ape group fig. 1. complete lingual cingulum on udp4 scored as 3. 7 visible pit or fovea along the mesial or distal marginal ridge of the tooth was scored as an anterior or posterior fovea respectively. lower deciduous molars. scores for 19 traits on the lower deciduous dentition were recorded for this study. the first takes note of the presence or absence of the metaconid on the lower first deciduous molar (ldp3) and its placement relative to the protoconid. the placement of the metaconid relative to the protoconid has been described both as variable in the permanent lower first and second premolars (lp3 and lp4) of pan (bailey, 2008) and as distal to the protoconid in ldp3 in the great apes (swindler, 2005). jørgensen (1956) also describes the distal metaconid in human deciduous teeth, but mentions that in the great apes the metaconid may be “faint or absent.” based on these reports and early observations, metaconids were scored in this study as absent (0), mesial to the protoconid (1), central to the protoconid (2) or distal to the protoconid (3). based on ludwig’s (1957) description of the metaconid based on where it sits relative to “the long axis of the median ridge of the buccal cusp,” the metaconid is scored as distal if the majority of the metaconid is distal to the median ridge of the protoconid, on the other hand, if the metaconid appears to sit directly on the axis of the median ridge of the protoconid then it is considered central. the entoconid, hypoconid and hypoconulid are also scored on ldp3 and ldp4. the entoconid and hypoconid were scored as either present or absent and the hypoconulid was scored according to the asudas from 0 to 5 with an additional value denoting a hypoconulid that was clearly present but could not be sized due to heavy wear (7). the mid-trigonid crest is an enamel ridge on ldp4 that connects the protoconid and metaconid (figure 3). it is mesial to the distal trigonid crest that connects the same cusps. the mid-trigonid crest may also be called a complete bridge formed by the mesial accessory ridges of the protoconid and metaconid (hooijer, 1948; scott and turner, 1997), or the anterior transverse ridge (jørgensen, 1956). although there is an asudas scoring plaque for this trait, the present study used a modified form of a scoring system presented by bailey (2002) that better fit the variation found in great ape deciduous molars. the mid-trigonid crest was scored based on the absence of a crest (0), the presence of two accessory ridges that did not coalesce to form a crest (1), the presence of a crest interrupted by a mesio-distal groove (2), or the presence of an uninterrupted crest (3). the presence of the anterior fovea on ldp4 was dependent on the presence of the mid-trigonid crest, because without a crest between the anterior fovea and the trigonid basin, the two are indistinguishably joined. the distal trigonid crest sits distal to the mid-trigonid crest, connecting the more distal portions of the protoconid and metaconid (figure 3). scott and turner (1997) call it the distal trigonid crest, but it has also been referred to as an extension of the distal accessory ridges of the protoconid and metaconid (scott and turner, 1997), the posterior trigonid crest (weidenreich, 1937), the oblique crest (jørgensen, 1956), or the transverse crest (jørgensen, 1956). when the mid-trigonid crest is absent and there is only one crest connecting the protoconid and metaconid it is still called the distal trigonid crest in the present study, but it may be called the protocristid elsewhere (swindler, 2005). the distal trigonid crest was scored in the same manner as the mid-trigonid crest. the deflecting wrinkle in ldp4 is an enamel extension that goes buccally from the metaconid and then curves distally. this trait was ranked according to the asudas as absent (0), weak (1), moderate (2), or marked (3). there are several traits that involve either the division of existing cusps into multiple elements or the overall number of cusps on the teeth. both the hypoconulid, following jørgensen’s (1956) ob fig. 2. buccal cingulum on udp4 scored as present. 8 servations of ldp4 in humans, and the entoconid were examined for a division in the cusp. these were each scored as either present or absent. the protostylid coming off of the disto-buccal edge of the protoconid on ldp4 was scored from 0 to 7 following the asudas. the expression of cusp 6 on ldp4 appears as a cusp on the distal margin of the tooth between the hypoconulid and the entoconid. this trait was ranked from 0 to 5 with the asudas. it may be important to note that a small cusp 6 may resemble a divided hypoconulid but that a divided cusp should have a single split apex while a cusp 6 will have its own apex distinct from the apex of the hypoconulid. additionally, cusp 7 appears as a small cusp on the lingual margin of ldp4 between the metaconid and entoconid. it was scored using the asudas from 0 to 5 as well. fissure pattern was observed in ldp4 and was scored as y, + or x according to definitions given by scott and turner (1997). as stated previously, the anterior fovea on ldp4 is a depression between the mesial marginal ridge and the mid-trigonid crest. it was scored as either present or absent. the posterior fovea was scored differently, however, because it was often more observable than the anterior or posterior foveae on udp4. this allowed it be scored as absent (0), a pit (1) or a fovea (2), where a pit is a depression bordered by the distal marginal ridge and a fovea is a depression that interrupts the distal marginal ridge. analysis for statistical analysis the traits were dichotomized using threshold values such that all traits were converted to either presence or absence. table 2 includes the list of traits and their thresholds for presence. following turner et al. (1991), any occurrence of a trait in an individual was counted as presence, even if occurrence was unilateral. this way, traits were analyzed according to the number of individuals as opposed to the number of teeth. metaconid placement and fissure pattern could not be converted to this form for analysis. these two traits were left in their original state and were analyzed by tooth instead of by individual. frequencies of occurrence for each trait were compared between pairs of groups using fisher’s exact test. analysis among the groups was conducted using the chi-square test. both analyses were done using pasw statistics 18.0. phenetic distance among the groups was then assessed using irish's (2010) adaptation of c.a.b. smith’s (1977) mean measure of divergence (mmd) formula. in order to further study the relatedness of the sample groups, the mean measures of divergence for pair-wise comparisons of the five groups were computed. first kendall’s tau-b test was used to find any correlated traits. out of the twenty-six dichotomized traits, four (udp3 lingual cingulum with udp4 lingual cingulum and ldp4 anterior fovea with ldp4 mid-trigonid crest) were correlated and four (ldp3 cusp 5, ldp4 entoconid, ldp4 hypoconid, and ldp4 hypoconulid division) were invariable (i.e. fixed as either all present or all absent) and therefore correlated with all of the other traits. all of the invariable traits and half of the correlated traits were removed, since without their related traits the other two would be uncorrelated. the lingual cingulum on udp4 was kept, since it showed greater variation than udp3 lingual cingulum, and ldp4 mid-trigonid crest was chosen instead of the ldp4 anterior fovea, since the presence of an anterior fovea is dependent on the presence of a mid-trigonid crest. metaconid position on ldp3 and fissure pattern on ldp4 could not be used for the mmd analysis since these traits were not expressed through presence or absence, so metaconid position was converted for analysis and fissure pattern was excluded. the 21 remaining traits were then used for mmd calculations using the freeman and tukey transformation for small samfig. 3. mid-trigonid and distal trigonid crests both scored as 3. 9 ple size. the final equation for the mean measure of divergence was (irish, 2010): where r represents the number of uncorrelated traits, θ denotes the angular transformation, which was calculated as: θ = (1/2) sin -1 (1-(2k)/(n+1)) + (1/2) sin -1 (1-2(k+1)/ (n+1)) i represents the trait, n represents the number of individuals examined for the trait, and k represents the number of individuals for whom the trait was present. the mmd was calculated for pair-wise comparisons of each group (table 3). in order to test the significance of the mmds the variance of each pair-wise comparison was calculated using: the square root of this var(mmd) value is the equivalent of the standard deviation, and if the mmd > 2 x √var(mmd), the null hypothesis that the proportion of occurrence in sample 1 is equal to the proportion of occurrence in sample 2 is rejected at the 0.025 level (harris and sjøvold, 2004; irish, 2010). results frequency analysis frequencies of each trait in all groups are listed in table 2. there was no difference in trait frequencies between males and females in any group, so both sexes were pooled for all analyses. there were several traits that showed statistically significant differences between the various subspecies, species, and genera that were studied. there are five traits that are significantly different between p. t. troglodytes and p. t. schweinfurthii (table 2). this is a surprisingly large number of differences since they are very closely related. compared to these two subspecies of chimpanzee g. g. gorilla and g. b. graueri, which belong to two different species, also had five traits with significant differences. however, the low variability in gorilla trait frequencies may be a result of sample size differences. the differences between the two gorilla species are less likely to appear statistically significant because there are so many fewer cases studied. there are six traits that exhibit significant differences in frequency between p. troglodytes and p. paniscus. between pan and gorilla eleven traits were found that varied significantly. this is the most variability shown between any of the groups and likely reflects the fact that these genera are the most distantly related of any of the groups studied. mean measure of divergence all of the pair-wise comparisons between the primate groups are significant, but the value of these findings is unclear since they demonstrate that g. g. gorilla is more similar to p. paniscus than to g. b. graueri when they are otherwise morphologically dissimilar. the fact that these values show that there is variation between the groups is, at the moment, more important than how much the groups vary and in what ways. the differences show that there is significant variation in the deciduous molars of chimpanzees, bonobos and gorillas that is comparable to variation found in the adult dentition. therefore, the deciduous dentition does show potential to be used similarly to adult dentition in research of ape population movement and genetic drift. discussion and conclusions the data presented above support several findings of past researchers regarding morphological characteristics, with some exceptions. as observed by swindler (2005), there were no observable fifth cusps on ldp3 and all observable teeth exhibited the y fissure pattern. however, lingual and buccal cingula in the upper dentition were present far more often than was described in the past (swindler, 2005). additionally, there are similarities seen between traits of primate adult and deciduous dentition. for example, cusp 6 on ldp4 and the lower first adult molar (lm1) seems to be expressed in p. troglodytes but not in p. paniscus (bailey, 2008; swindler, 2005). cusp 6 is observed on lm1 in 16.2% of p. t. troglodytes and 2.3% of p. t. schweinfurthii, but none are observed in p. paniscus (bailey, 2008), while on ldp4 cusp 6 was found in 23.5% of p. t. troglodytes and 24.2% of p. t. schweinfurthii and not at all in p. paniscus. cusp 7 on the same tooth is expressed in 9.1% of adult p. paniscus (bailey, 2008) and in 8.3% of juvenile p. paniscus and it is present in gorilla, but it appears in neither adult nor juvenile p. troglodytes (bailey, 2008; swindler, 2005). the results of mmd analysis are of particular interest when they are compared with another mmd analysis of similar non-metric dental traits in adult pan (bailey, 2008). although the two data sets are quite different, there are some important similarities. similar to bailey’s findings, we find 10 t a b l e 2 .t ra it f re q u e n c ie s a c ro ss s p e c ie s a n d s u b sp e c ie s w it h th e n u m b e r o f in d iv id u a ls ( o r n u m b e r o f te e th f o r m e ta c o n id p o si ti o n a n d f is su re p a tt e rn ) o b se rv e d . c o lu m n s o n t h e r ig h t re p re se n t p -v a lu e s fo r f is h e r’ s e x a c t te st . a b b re v ia ti o n s p p a n ; p t p . tr o g lo d y te s; p t t p . t. t ro g lo d y te s; p t s p . t. s c h w e in fu rt h ii ; p p p .p a n is c u s; g g o ri ll a ; g g g g . g o ri ll a g o ri ll a ; g b g g .b e ri n g e i g ra u e ri . t ra it s a ll p t p t t p t s p p g g g g b g p t t v s. p t s g g g v s. g b g p t v s. p p p v s. g t ra n sv e rs e c re st ( u d p 3 ) + = 2 -3 ( p re se n t st u d y ) 3 5 .3 (5 1 ) 4 3 .5 (2 3 ) 2 8 .6 (2 8 ) 6 0 .0 (3 0 ) 2 2 .7 (2 2 ) 0 .0 ( 8 ) 0 .3 7 8 0 .1 8 5 0 .0 2 7 * 0 .0 0 5 * l in g u a l c in g u lu m ( u d p 3 ) + = 2 -3 ( p re se n t st u d y ) 1 .5 ( 6 8 ) 3 .7 ( 2 7 ) 0 .0 (4 1 ) 3 .1 (3 2 ) 4 .3 ( 2 3 ) 6 2 .5 (8 ) 0 .3 9 7 0 .0 0 2 * 0 .5 3 9 0 .0 0 2 * l in g u a l c in g u lu m ( u d p 4 ) + = 2 -3 ( p re se n t st u d y ) 1 9 .0 (8 4 ) 3 4 .4 (3 2 ) 9 .6 (5 2 ) 2 4 .2 (3 3 ) 4 4 .0 (2 5 ) 1 0 0 (9 ) 0 .0 0 6 * 0 .0 0 3 * 0 .3 4 8 0 .0 0 0 * b u c c a l c in g u lu m ( u d p 3 ) + = a n y e x p re ss io n 4 .0 ( 7 5 ) 1 0 .3 (2 9 ) 0 .0 (4 6 ) 2 .6 (3 9 ) 0 .0 ( 2 6 ) 2 5 .0 (8 ) 0 .0 5 4 0 .0 5 0 * 0 .5 7 7 0 .4 1 9 b u c c a l c in g u lu m ( u d p 4 ) + = a n y e x p re ss io n 8 .3 ( 8 4 ) 1 2 .5 (3 2 ) 5 .8 (5 2 ) 2 .4 (4 1 ) 8 .0 ( 2 5 ) 7 2 .2 (1 1 ) 0 .2 4 6 0 .0 0 0 * 0 .1 9 5 0 .0 0 1 * c ri st a o b li q u a ( u d p 4 ) + = u n in te rr u p te d 6 9 .8 (8 6 ) 5 0 .0 (3 2 ) 8 1 .5 (5 4 ) 7 3 .3 (3 0 ) 8 7 .0 (2 3 ) 1 0 0 (1 0 ) 0 .0 0 2 * 0 .3 2 5 0 .4 5 2 0 .0 1 2 * c u sp 5 ( u d p 4 ) + = a s u 1 -5 3 .5 ( 8 6 ) 5 .7 ( 3 5 ) 2 .0 (5 1 ) 5 .1 (3 9 ) 4 .2 ( 2 4 ) 9 .1 (1 1 ) 0 .3 6 0 0 .5 3 6 0 .4 9 8 0 .4 7 7 a n te ri o r fo v e a ( u d p 4 ) + = a n y e x p re ss io n 6 8 .7 (8 3 ) 5 0 .0 (3 4 ) 8 1 .6 (4 9 ) 2 9 .0 (3 1 ) 4 4 .0 (2 5 ) 6 0 .0 (1 0 ) 0 .0 0 2 * 0 .3 1 5 0 .0 0 0 * 0 .2 1 8 p o st e ri o r fo v e a ( u d p 4 ) + = a n y e x p re ss io n 7 8 .8 (8 0 ) 6 5 .7 (3 5 ) 8 8 .9 (4 5 ) 9 4 .1 (3 4 ) 8 3 .3 (2 4 ) 1 0 0 (1 1 ) 0 .0 1 3 * 0 .2 0 3 0 .0 3 5 * 0 .3 2 5 m e ta c o n id ( ld p 3 ) + = a n y e x p re ss io n 1 0 0 .0 (7 2 ) 1 0 0 .0 (3 0 ) 1 0 0 .0 (4 2 ) 9 1 .9 (3 7 ) 8 7 .5 (2 4 ) 8 1 .8 (1 1 ) c o n st a n t 0 .5 0 9 0 .0 3 7 * 0 .0 2 1 * 11 t a b l e 2 c on t’ d . t ra it s a ll p t p t t p t s p p g g g g b g p t t v s. p t s g g g v s. g b g p t v s. p p p v s. g m e ta c o n id p o si ti o n ( ld p 3 ) 1 = m e si a l 2 = c e n tr a l 3 = d is ta l (p -v a lu e s fo r d is ta l) 1 = 0 .8 2 = 9 .5 3 = 8 9 .7 (1 2 6 ) 1 = 0 2 = 1 6 .7 3 = 8 3 .3 (5 4 ) 1 = 1 .4 2 = 4 .2 3 = 9 4 . 4 ( 7 2 ) 1 = 0 .0 2 = 2 0 .3 3 = 7 9 .7 (5 9 ) 1 = 0 .0 2 = 2 5 .7 3 = 7 4 .3 (3 5 ) 1 = 0 .0 2 = 2 6 .7 3 = 7 3 .3 (1 5 ) 0 .0 4 2 * 0 .6 7 0 0 .0 6 3 0 .0 3 3 * e n to c o n id ( ld p 3 ) + = a n y e x p re ss io n 6 8 .1 (4 7 ) 5 6 .0 (2 5 ) 8 1 .8 (2 2 ) 8 6 .7 (3 0 ) 8 5 .7 (1 4 ) 8 0 .0 (1 0 ) 0 .0 5 6 0 .8 2 2 0 .0 5 5 0 .3 0 3 e n to c o n id ( ld p 4 ) + = a n y e x p re ss io n 1 0 0 (8 5 ) 1 0 0 (3 5 ) 1 0 0 (5 0 ) 1 0 0 (4 4 ) 1 0 0 (2 4 ) 1 0 0 (1 1 ) c o n st a n t c o n st a n t c o n st a n t c o n st a n t h y p o c o n id ( ld p 3 ) + = a n y e x p re ss io n 1 0 0 (8 0 ) 1 0 0 (3 6 ) 1 0 0 (4 4 ) 1 0 0 (4 1 ) 6 8 .2 (2 2 ) 1 0 0 (1 1 ) c o n st a n t 0 .0 4 0 * c o n st a n t 0 .0 0 0 * h y p o c o n id ( ld p 4 ) + = a n y e x p re ss io n 1 0 0 (8 9 ) 1 0 0 (3 6 ) 1 0 0 (5 3 ) 1 0 0 (4 5 ) 1 0 0 (2 4 ) 1 0 0 (1 1 ) c o n st a n t c o n st a n t c o n st a n t c o n st a n t c u sp 5 ( ld p 3 ) + = a s u 1 -5 0 .0 ( 8 2 ) 0 .0 ( 3 2 ) 0 .0 (4 7 ) 0 .0 (3 9 ) 0 .0 ( 2 5 ) 0 .0 (1 1 ) c o n st a n t c o n st a n t c o n st a n t c o n st a n t c u sp 5 ( ld p 4 ) + = a s u 1 -5 9 8 .8 (8 5 ) 1 0 0 (3 5 ) 9 8 .0 (5 0 ) 1 0 0 (3 9 ) 1 0 0 (2 4 ) 1 0 0 (1 1 ) 0 .5 8 8 c o n st a n t 0 .6 8 5 0 .7 8 0 d e fl e c ti n g w ri n k le ( ld p 4 ) + = a s u 2 -3 7 .5 ( 5 3 ) 9 .1 ( 3 3 ) 5 .0 (2 0 ) 3 .3 (3 0 ) 4 .8 ( 2 1 ) 0 .0 ( 8 ) 0 .5 3 7 0 .7 2 4 0 .4 0 1 0 .5 1 0 m id -t ri g o n id c re st ( ld p 4 ) + = 2 -3 ( p re se n t st u d y ) 4 8 .3 (5 8 ) 4 4 .8 (2 9 ) 5 1 .7 (2 9 ) 6 6 .7 (3 6 ) 8 1 .0 (2 1 ) 6 0 .0 (1 0 ) 0 .3 9 7 0 .2 0 8 0 .0 6 2 0 .0 4 8 * d is ta l tr ig o n id c re st ( ld p 4 ) + = 2 -3 ( p re se n t st u d y ) 1 0 0 (7 6 ) 1 0 0 (3 3 ) 1 0 0 (4 3 ) 9 7 .6 (4 2 ) 9 0 .9 (2 2 ) 1 0 0 (1 1 ) c o n st a n t 0 .4 3 8 0 .3 5 6 0 .1 2 0 12 t a b l e 2 c on t’ d . t ra it s a ll p t p t t p t s p p g g g g b g p t t v s. p t s g g g v s. g b g p t v s. p p p v s. g p ro to st y li d ( ld p 4 ) + = a s u 3 -7 1 .3 ( 7 9 ) 0 .0 ( 3 5 ) 2 .3 (4 4 ) 0 .0 (3 9 ) 7 8 .3 (2 3 ) 1 0 0 (1 1 ) 0 .5 5 7 0 .1 2 1 0 .6 6 9 0 .0 0 0 * d iv is io n o f h y p o c o n u li d (l d p 4 ) + = a n y e x p re ss io n 0 .0 ( 6 9 ) 0 .0 ( 3 5 ) 0 .0 (3 4 ) 0 .0 (1 7 ) 0 .0 ( 2 1 ) 0 .0 (1 1 ) c o n st a n t c o n st a n t c o n st a n t c o n st a n t d iv is io n o f e n to c o n id ( ld p 4 ) + = a n y e x p re ss io n 3 .8 ( 7 8 ) 5 .7 ( 3 5 ) 2 .3 (4 3 ) 0 .0 (3 6 ) 0 .0 ( 2 3 ) 0 .0 (1 1 ) 0 .4 2 2 c o n st a n t 0 .3 1 6 0 .4 5 4 c u sp 6 ( ld p 4 ) + = a s u 1 -5 2 3 .9 (6 7 ) 2 3 .5 (3 4 ) 2 4 .2 (3 3 ) 0 .0 (1 8 ) 4 .5 ( 2 2 ) 0 .0 (1 1 ) 0 .6 3 9 0 .6 6 7 0 .0 1 4 * 0 .0 2 1 * c u sp 7 ( ld p 4 ) + = a s u 2 -4 0 .0 ( 7 9 ) 0 .0 ( 3 5 ) 0 .0 (4 4 ) 8 .3 (3 6 ) 0 .0 ( 2 4 ) 9 .1 (1 1 ) c o n st a n t 0 .3 1 4 0 .0 2 9 * 0 .7 6 8 a n te ri o r fo v e a ( ld p 4 ) + = a n y e x p re ss io n 5 5 .2 (5 8 ) 5 1 .7 (2 9 ) 5 8 .6 (2 9 ) 6 0 .0 (3 5 ) 7 6 .2 (2 1 ) 6 0 .0 (1 0 ) 0 .3 9 6 0 .3 0 2 0 .4 0 6 0 .1 2 1 p o st e ri o r fo v e a ( ld p 4 ) + = a n y e x p re ss io n 4 5 .0 (6 0 ) 3 5 .3 (3 4 ) 5 7 .7 (2 6 ) 5 7 .1 (1 4 ) 6 1 .9 (2 1 ) 4 0 .0 (1 0 ) 0 .0 7 1 0 .2 2 4 0 .3 0 1 0 .2 0 8 f is su re p a tt e rn ( ld p 4 ) + = y 1 0 0 (1 2 7 ) 1 0 0 (6 4 ) 1 0 0 (6 3 ) 1 0 0 (6 0 ) 1 0 0 (4 5 ) 1 0 0 (2 2 ) c o n st a n t c o n st a n t c o n st a n t c o n st a n t 13 that p. paniscus is more similar to p. t. schweinfurthii than it is to p. t. troglodytes. we also found that the two p. troglodytes subspecies are more similar to each other than either is to p. paniscus, which fits with bailey's data (2008) and the substantial genetic and morphological evidence that indicates that the two p. troglodytes subspecies are more closely related to each other than to p. paniscus. there are also several unexpected similarities between the deciduous teeth of p. paniscus and g. g. gorilla. mmd analysis indicates that g..g. gorilla is more similar to p. paniscus than it is to the other gorilla species or p. troglodytes. however, since researchers overwhelmingly conclude that g..g. gorilla is more closely related to other groups within the gorilla genus than to the pan genus, we assume that these similarities are due primarily to chance and not to a genetic closeness between the two very different species. the point here is that while the data do not give an entirely accurate view of how these subspecies and species are related, they can show that these groups display significant variation in their deciduous dental traits and that future research could perhaps give a more accurate estimation of those differences. it is important to note the size of the samples used in this study. while our numbers of individuals observed were similar to those of bailey (2008) for pan, the number of observable samples of each trait is substantially lower, and for many important traits bailey uses more observable samples. while it would clearly be helpful to have data on more deciduous teeth, it would also be useful to have more data on adult teeth to compare with this study to show more concretely whether deciduous teeth exhibit the same patterns as adult teeth. by using many traits across a larger variety of teeth, studies in the future will be able to produce more reliable data on the deciduous primate dentition. acknowledgements financial support was provided by the paul anderson interdisciplinary summer research fund and macalester college. we would like to thank john soderberg and martha tappen at the university of minnesota, wim wendelen and emmanuel gilissen at the royal museum of central africa, and angela gill and malcolm harman at the quex museum house and gardens for access to their primate skeletal collections. finally special thanks to brad belbas at macalester college for database interface creation, chris schmidt, and our two anonymous reviewers. literature cited bailey se. 2002. a closer look at neanderthal post canine dental morphology: the mandibular dentition. anat rec 269:148-156. bailey se. 2008. interand intra-specific variation in pan tooth crown morphology: implications for neandertal taxonomy. in: irish jd, nelson gc, editors. technique and application in den tal anthropology cambridge: cambridge uni versity press. p 293-316. hanihara t. 2008. morphological variation of ma jor human populations based on nonmetric den tal traits. am j phys anthropol 136:169-182. harris ef, sjøvold t. 2004. calculation of smith's mean measure of divergence for intergroup comparisons using nonmetric data. dent an thropol 17:83-93. ptt pts pp ggg gbg ptt 0.074 (0.02) 0.099 (0.02) 0.328 (0.02) 0.806 (0.04) pts 0.102 (0.02) 0.270 (0.02) 0.935 (0.04) pp 0.243 (0.02) 0.733 (0.04) ggg 0.456 (0.04) gbg table 3. mean measure of divergence values (with variance values) for pair-wise comparison of the five african ape groups. abbreviations described in table 2 14 hooijer da. 1948. prehistoric teeth of man and of the orang-utan from central sumatra, with notes on the fossil orang-utan from java and southern china. zoologische mededelingen 29:175-301. irish jd. 2006. who were the ancient egyptians? dental affinities among neolithic through post dynastic peoples. am j phys anthropol 129:529 543. irish jd. 2010. the mean measure of divergence: its utility in model-free and model-bound analy ses relative to the mahalanobis d2 distance for nonmetric traits. am j hum biol 22:378-395. jørgensen kd. 1956. the deciduous dentition: a descriptive and comparative anatomical study. acta odontol scand 14:1-235. kraus bs, jordan re, abrams l. 1969. dental anat omy and occlusion; a study of the masticatory system. baltimore: williams and wilkins. ludwig fj. 1957. the mandibular second premo lars: morphologic variation and inheritance. journal of dental research 36:263-273. ortiz a, skinner mm, bailey se, hublin jj. 2010. carabelli's trait expression at the enamel-dentin junction (edj) and outer enamel surface (oes) of pan maxillary molars. am j phys anthropol 141:182-183. scott gr, turner cg ii. 1997. the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cam bridge; new york: cambridge university press. smith cab. 1977. a note on genetic distance. ann hum genet 40(4):463-479 swarts jd. 1988. deciduous dentition: implications for hominoid phylogeny. in: schwartz jh, editor. orang-utan biology. new york: oxford university press. p 263-270. swindler dr. 2005. primate dentition: an intro duction to the teeth of non human primates. cambridge: cambridge university press. turner cg ii, nichol c, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state univer sity dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental an thropology. new york: wiley-liss. p 13-31. weidenreich f. 1937. the dentition of sinanthro pus pekinensis: a comparative odontography of the hominids. palaeontologica sinica new series d. no. 1: 1-180. ortiz 2013.4 20 2012 dahlberg award winner: dental morphological variation among six pre-hispanic south american populations with implications for the peopling of the new world alejandra ortiz new york university, new york, ny 10003 keywords: discrete dental traits, asudas, dental variation, south american indians abstract the analysis of the human dentition provides important information on the origins and dispersals of the first american inhabitants. however, most of this work has focused on north america, whereas less research has been devoted to variation within central and south america. this study examines the permanent dentitions of 340 individuals from six pre-hispanic south american populations and places them in the broader context of the peopling of the new world. non-metric dental data were collected using the arizona state university dental anthropology system (asudas). intraand inter-regional comparisons were assessed using the mean measure of divergence statistical program. all samples are characterized by relatively high frequencies of um1 enamel extension and lm1 deflecting wrinkle and low frequencies of um1 cusp 5 and lm2 y-groove pattern. although preliminary, results indicate that populations from chile, venezuela and peru-northern coast are dentally similar and follow the sinodont dental pattern. the perusouthern highlands sample is the most divergent of the south american groups examined, showing the closest affinities with sundadonts. finally, no clear pattern was found for bolivia and peruamazonian andes, as most of their trait frequencies fall within the range of overlap between sinodont and sundadont populations. since columbus reached the new world in 1492 and found it already inhabited by humans, one of the most enduring debates among scholars and early natural historians has centered on the origins of the first american inhabitants. until the 1980s, the predominant view was that one single founding group, represented archaeologically by the clovis culture, first entered the americas after the last glacial maximum (lgm) via the bering land bridge (martin, 1973; lynch, 1983). the clovis-first model hypothesized that around 13,000 years ago people migrated from siberia to alaska tracking big game animal herds and that in a few millennia spread rapidly from beringia to tierra del fuego (dillehay, 1999, 2000, 2009; meltzer, 2004; goebel et al., 2008). in accord with this model, greenberg et al. (1986) published a widely cited, yet highly controversial, three-wave model for the peopling of the new world. based on the linguistic, dental and genetic evidence available at that time, they argued that the first americans came from northeast asia in three separate waves of migration. following greenberg et al. (1986), the first migration would have involved the ancestors of amerind-speaking populations from south, central and most of north america. these first settlers would have been associated with the biggame hunting clovis culture and its rapid spread throughout the american continent. the second migratory wave would have been associated with the ancestors of na-dene speakers from the western half of the north american subarctic, including the north pacific coast. the third and last migratory wave from northeast asia would have involved the ancestors of aleut-eskimo populations, occupying territories from western alaska to eastern greenland. over the past 25 years, several archaeological sites in the arctic and the americas have provided compelling evidence for human occupation predating clovis (e.g., dillehay, 1997, 2000; adovasio et al., 1998; pitulko et al., 2004; goodyear, 2005). relatively recent genetic and craniofacial studies have also brought both the clovis-first and threewave models into question. for example, molecular data suggest a single and early (i.e., pre-clovis) migration for the peopling of the new world (bonatto and salzano, 1997; schurr, 2004; zegura et al., 2004; tamm et al., 2007; wang et al., 2007; fagundes et al., 2008a,b). mitochondrial dna (mtdna) analyses have revealed that the majority of native americans (including na-dene and aleut-eskimo) belong to five distinct mtdna haplogroups, which have been identified as a-d and correspondence to: alejandra ortiz, department of anthropology, new york university, 25 waverly place, new york, ny 10003. email: ao706@nyu.edu 21 x (schurr, 2004). furthermore, zegura et al. (2004) demonstrated that these populations exhibit, almost exclusively, y-chromosome haplogroups q and c. although all these lineages can be traced back to modern northeast asians, recent genetic data from native american samples reveal the presence of autochthonous mutations of particular mtdna and y-chromosome haplogroups, which cannot be explained by old clovis paradigms (tamm et al., 2007; fagundes et al., 2008a,b). in this regard, and although the exact pre-clovis timing of migration remains controversial (for reviews see schurr, 2004), geneticists seem to concur that a population expansion with its roots in beringia occurred by the end of the lgm, followed by a rapid settlement of the continent along a pacific coastal route (bonatto and salzano, 1997; tamm et al., 2007; wang et al., 2007; fagundes et al., 2008a,b). research on craniofacial variation among early american populations also suggests an early date for the peopling of the new world (powell and neves, 1999; pucciarelli et al., 2003; neves et al., 2003; neves and hubbe, 2005; hubbe et al., 2011). contrary to interpretations based on molecular markers, these studies have proposed that the new world was initially occupied by two biologically and chronologically distinct human groups. advocates of this two-wave model argue that the ancestors of a morphologically generalized (or non -specialized mongoloid) “paleoamerican” population first migrated to the new world and were later replaced by the ancestors of the “amerindians,” who carried the highly derived northeast asian (or mongoloid-sinodont) phenotype. lahr (1995) considers that the high level of diversity observed among native americans, including both paleoamericans and amerindians, can be explained by a single, albeit not necessarily earlier, migration of non-specialized mongoloids that entered the americas before many mongoloid -sinodont traits spread throughout northeast asia. more recently, gonzález-josé et al.’s (2008) analysis of modern human cranial variation also suggests a single origin for all native americans. contrary to lahr (1995), however, they propose a pre-clovis occupation of the new world and emphasize the critical role that beringia played in shaping the native american pattern of variation. although considerable advances have been made since the publication of greenberg et al.’s (1986) model, our understanding of the real extent of dental morphological variation across the americas remains elusive. turner’s pioneering research on dental morphology demonstrated the usefulness of non-metric traits for assessing human biological relationships and reconstructing human population history (turner, 1984, 1986, 1987, 1990, 1993; scott and turner, 1997). based on his work, however, native americans have been regarded as a rather biologically and phenotypically homogeneous human group, sharing a strict sinodont dental pattern (but see haydenblit, 1996). nevertheless, the apparent homogeneity of native american populations, and their close association with modern northeast asians, may be attributed to the fact that our characterization of native american dental morphology has largely been based on north america (dahlberg, 1951, 1963; moorrees, 1957; sofaer et al., 1972; turner, 1983, 1990, 1993; scott et al., 1983). in fact, relatively little work has concentrated on central (baume and crawford, 1978; haydenblit, 1996) and south (goaz and miller, 1966; kieser and preston, 1981; turner and bird, 1981; sutter and verano, 2007) america. furthermore, research in central and south america has generally focused on a limited number of dental traits in only a few populations. thus, attempts to assess biological affinities between south americans and other world populations have been relatively rare (e.g., turner and bird, 1981; turner, 1984, 1986; sutter, 2005; hanihara, 2008). to partially reconcile interpretations derived from dental morphology with those based on relatively recent craniofacial and genetic data, the present study reanalyzes dental affinities in the new world, with special attention to south american populations. two hypotheses are tested. hypothesis 1: if south americans are dentally homogeneous, no significant differences among groups are predicted. hypothesis 2: if all native americans have a relatively recent northeast asian origin, a shared sinodont dental pattern across all samples is predicted. the specific goals of this study are to: (1) describe south american dental morphology; (2) determine biological affinities among south american populations; and (3) compare their morphology with published data from major world populations showing either the sinodont or sundadont dental pattern. ultimately, i analyze dental morphological data to enhance our understanding 22 of south american origins and the initial peopling of the new world. materials and methods study sample this study examined the permanent dentitions of 340 individuals from six preor proto-hispanic south american populations. the geographic origin and number of individuals in each sample are presented in table 1. figure 1 illustrates the geographical range for each sample. except for the peru-amazonian andes sample, which is curated at the instituto nacional de cultura (chachapoyas, peru), all data were collected on skeletal remains housed at the american museum of natural history (new york, usa). in some cases, small collections were pooled to increase the sample size of specific regional populations. further details of sample composition are provided below. peru southern highlands (psh). this sample includes individuals from apurimac (n = 53) and puno (n = 8). both sites are located in the southern highlands of peru. all specimens belong to the von luschan collection. the time period during which these populations lived is not mentioned on museum records. however, some specimens present intentional cranial deformation and/or cranial trephination, suggesting that these populations lived during pre-hispanic times or had limited spanish influence.1 peru northern coast (pnc). a total of 37 prehispanic individuals recovered by junius bird (1985) during his expedition to the chicama, virú and moche valleys in the northern coast of peru make up this sample. the majority of specimens (n = 32) came from the huaca prieta archaeological site and belong either to the pre-ceramic period (ca. 3500–1300 b.c.) or the initial periodcupisnique times (ca. 1300-200 b.c.). no specific cultural affiliation has been attributed to the remaining five individuals. peru amazonian andes (paa). this sample consists of 62 individuals from the chachapoya culture, which occupied the territory between the northeastern flank of the andean cordillera and the northwestern portion of the amazonian forest. all individuals were recovered from primary or secondary burials at the archaeological complex of 1 artificial cranial deformation and cranial trephination were regular practices in pre-hispanic south america (imbelloni, 1925; munizaga, 1987). although these cultural practices have been forbidden since 1585, due to the spanish influence over the andean region (hoshower et al., 1995), a few cases have been reported in relatively isolated post-contact indigenous groups (bandelier, 1904; weiss, 1961; tommaseo and drusini, 1984). sample name code n time period peru southern highlands psh 61 preor proto-hispanic peru northern coast pnc 37 from pre-ceramic period to initial periodcupisnique times (ca. 3500-200 b.c.) peru amazonian andes paa 62 from late intermediate period to early spanish postcontact times (ca. 800 1532 a.d.) chile chi 41 from pre-ceramic period to early spanish postcontact times (ca. 3500 b.c.-1532 a.d.) venezuela ven 32 preor proto-hispanic bolivia bol 107 late intermediate period (ca. 1000-1400 a.d.) total 340 n = number of individuals examined table 1. south american samples used in this study 23 kuelap and have been dated to ca. 800 – 1532 a.d. (schjellerup, 1997). chile (chi). this sample consists of 41 individuals from north-central chile. the majority of the specimens analyzed (n = 24) was recovered by bird during his expedition to chile (bird, 2006). the remaining 17 individuals belong to different museum collections. all specimens date between the pre-ceramic period (ca. 3500–1300 b.c.) and early spanish post-contact times (ca. 1532 a.d.). venezuela (ven). this sample consists of 32 individuals. most (n = 26) are from la mata, an artificial mound situated on the shores of lake valencia in the maracay region (bennett, 1937). the la mata site was excavated by archaeologist wendell bennett during his 1932 expedition, where several pre-hispanic burials with no specific cultural affiliation were recovered. the remaining six individuals came from maracaibo and belong to the von luschan collection. bolivia (bol). the bolivian altiplano is represented by a sample of 107 individuals. they are dated to the late intermediate period, which extends from approximately 1000 to 1400 a.d. (bandelier, 1910). all specimens were recovered by adolph bandelier during his expedition to south america from1894 to 1898. . scoring procedures and statistical analysis dental morphological affinities among samples were assessed using the arizona state university dental anthropology system asudas (turner et al., 1991). to avoid misleading results attributed to european admixture, only presumed preor protohispanic individuals were included and analyzed. although data were collected on the complete set of asudas crown and root traits, only 21 tooth-trait combinations were used in this study. these combinations focus on the key tooth sensu dahlberg (1945), as well as traits whose sample sizes consist of at least three individuals in each group. furthermore, features that were consistently absent across samples (e.g., uc bushman canine) were removed from analysis. according to irish (2010), dropping traits that are nondiscriminatory across samples is the standard procedure, as their inclusion does not effectively contribute to group differentiation. teeth with occlusal wear or post mortem damage were analyzed to the extent that the trait observed was not obscured. previous investigations demonstrated the lack of sexual dimorphism of non-metric dental traits (turner, 1984; hanihara, 1992; irish, 1993, 1997; scott and turner, 1997), and thus males and females were combined in this study. trait frequencies were estimated using the individual count method of turner and scott (1977). this method suggests that the antimere exhibiting the strongest degree of trait expression is used in the analysis, as it is a more accurate indicator of the individual’s genotype (turner and scott, 1977; scott and turner, 1997). following sjøvold (1977), trait expression was dichotomized into categories of presence or absence to facilitate multivariate statistical analysis. all traits were dichotomized at the standard breakpoints according to the asudas (see table 2). levels of differentiation among samples were calculated using smith’s mean measure of divergence (mmd) multivariate statistic. this method provides a quantitative estimate of biological divergence between two given samples based on the degree of similarity across fig. 1. map of south america showing the geographical range of the six preor proto-hispanic andean populations used in this study. 24 the entire suite of traits (berry and berry, 1967; sjøvold, 1977; harris and sjøvold, 2004; irish, 2010). thus, a smaller value indicates greater affinity between comparative groups. divergence between two samples was considered significant at p ≤ 0.025, when the mmd value is greater than twice its standard deviation (sjøvold, 1977). small sample sizes were corrected using the freeman and tukey angular transformation. however, because of the correction factor, this transformation may yield negative mmd values (berry and berry, 1967; sjøvold, 1977; harris and sjøvold, 2004). these negative values are statistical artifacts and indicate no meaningful divergence between two samples. thus, the standard procedure is to set them at zero (harris and sjøvold, 2004; irish, 2010). finally, to place the six south american samples examined in a global context, trait frequencies were compared to other populations exhibiting either the sinodont or sundadont dental pattern (sensu turner, 1987, 1990). these included samples from north and southeast asia (turner, 1984, 1987, 1990), north america (turner, 1984, 1986), and mesoamerica-mexico (haydenblit, 1996). all comparative data were scored using the asudas. special attention was initially given to the eight diagnostic traits of the sinodont-sundadont division proposed by turner (1987, 1990): ui1 shoveling, ui1 double shoveling, up3 root number, um1 enamel extension, um3 peg/reduced/congenital absence, lm1 deflecting wrinkle, lm1 root number and lm2 cusp number. however, the lack of radiographic analysis precluded accurate observations of “present, but unerupted um3s”, so this feature was not included. trait selection for the inter-regional mmd analysis was based on the availability of published data with similar dichotomized breakpoints. intra-observer error intra-observer concordance for the 21 dental traits was assessed by rescoring 30 (five per sample) of the 340 individuals originally examined. scoring sessions were separated by five months. this analysis was performed by ao according to nichol and turner’s (1986) recommendations. the percentage of disagreements (of any magnitude) between the two scoring sessions was 4.6%. the percentage of disagreements of two or more grades between the first and second sessions was 0.3%. finally, the percentage of cases where traits after dichotomization would have been scored as “present” in one session and “absent” in the other was 1.9%. all these values are similar to those reported by nichol and tuner (1986). results trait frequencies of early south americans: do they all follow the sinodont pattern? frequency comparisons of 21 discrete dental traits in six south american populations are summarized in table 2. examples of these traits in south american upper dentitions are provided in figure 2. all samples are characterized by relatively high frequencies of um1 enamel extension, lm1 deflecting wrinkle and lm1 cusp 6 (except for psh), as well as low frequencies of up3-up4 odontome, um1 cusp 5 and lm2 y-groove pattern. they also show low to intermediate frequencies of lm1 cusp 7. frequencies of occurrence of these traits fall within the range of variation of sinodont populations (turner, 1987, 1990; scott and turner, 1997). furthermore, in accordance with the sinodont dental pattern, south americans exhibit high frequencies of ui1 shoveling, with the exception of psh and bol, whose intermediate frequencies of ui1 shoveling more closely approximate those of jomonese and ainu populations (turner, 1987, 1990). while the incidence of ui1 double-shoveling is also high in the pnc, paa and chi samples, psh, bol and ven have more sundadont-like frequencies of occurrence of this trait. moreover, except for bol, all samples show high frequencies of four-cusped lm2 (or hypoconulid absence). the absence of the hypoconulid on lm2 is more common in sundadont than in sinodont populations (turner, 1990). in general, there is a broad range of overlap between sinodonts and sundadonts regarding the incidence of multi-rooted up3. the psh, pnc and bol samples exhibit intermediate frequencies of this feature, falling within this range of overlap. in contrast, multi-rooted up3 does not frequently occur in chi and ven, and thus they more closely align with sinodonts. except for bol, all samples show intermediate to high frequencies of um1 carabelli’s trait. this is surprising not only because trait presence was limited to grades 3-7 (as opposed to turner’s [1987] dichotomizing breakpoint of grades 2-7), but also 25 % n % n % n % n % n % n w in g in g u i1 (+ = a s u 1 ) 2 1 .4 1 4 0 .0 1 8 1 9 .4 3 6 1 0 .0 2 0 3 3 .3 3 3 0 .0 1 0 s h o v el in g u i1 (+ = a s u 2 -6 ) 4 0 .0 1 0 9 2 .9 1 4 5 9 .4 3 2 6 0 .0 1 0 8 3 .3 6 4 0 .0 5 d o u b le s h o v el in g u i1 (+ = a s u 2 -6 ) 1 0 .0 1 0 5 3 .8 1 3 3 5 .1 3 7 5 0 .0 1 2 1 6 .7 6 1 4 .3 7 in te rr u p ti o n g ro o v e u i2 (+ = a s u + ) 1 0 .5 1 9 3 6 .8 1 9 3 4 .2 3 8 9 .1 2 2 0 .0 5 2 2 .2 1 8 t u b er cu lu m d en ta le u i2 (+ = a s u 2 -6 ) 3 5 .0 2 0 2 1 .1 1 9 2 1 .6 3 7 1 0 .0 2 0 2 0 .0 5 1 5 .8 1 9 d is ta l ac ce ss o ry r id g e u c (+ = a s u 2 -5 ) 2 2 .2 1 8 5 0 .0 1 0 2 8 .6 2 8 2 5 .0 8 2 5 .0 4 7 .7 2 6 o d o n to m e u p 3 -u p 4 (+ = a s u 1 ) 0 .0 2 9 5 .9 1 7 1 .9 5 2 0 .0 1 0 0 .0 1 1 6 .3 4 8 r o o t n u m b er u p 3 (+ = a s u 2 + ) 2 6 .3 1 9 2 8 .6 1 4 -ǂ -ǂ 1 6 .7 6 0 .0 6 3 7 .5 4 8 h y p o co n e u m 2 (+ = a s u 2 -5 ) 9 1 .7 3 6 9 0 .0 2 0 7 9 .1 4 3 1 0 0 .0 1 6 8 8 .9 9 9 3 .2 7 3 c u sp 5 u m 1 (+ = a s u 1 -5 ) 0 .0 4 0 6 .3 1 6 3 .8 5 2 7 .7 1 3 0 .0 8 7 .4 5 4 c ar ab el li 's t ra it u m 1 (+ = a s u 3 -7 ) 2 2 .6 3 1 5 0 .0 1 2 3 4 .0 4 7 6 2 .5 8 6 9 .2 1 3 1 2 .5 4 8 p ar as ty le u m 3 (+ = a s u 1 -5 ) 4 .0 2 5 1 5 .4 1 3 1 4 .3 2 1 7 .1 1 4 0 .0 6 0 .0 3 8 e n am el e x te n si o n u m 1 (+ = a s u 2 -3 ) 4 8 .7 3 9 6 6 .7 1 5 4 0 .0 5 0 4 5 .0 2 0 3 6 .4 1 1 3 2 .4 3 7 a n te ri o r fo v ea l m 1 (+ = a s u 2 -4 ) 1 1 .1 9 1 1 .1 9 2 7 .3 3 3 3 3 .3 3 4 2 .9 7 5 0 .0 4 g ro o v e p at te rn l m 2 (+ = a s u y ) 1 6 .7 1 8 7 .1 1 4 1 4 .6 4 8 1 6 .7 1 8 9 .1 1 1 6 .3 1 6 c u sp n u m b er l m 1 (+ = a s u 6 + ) 1 1 .8 1 7 4 6 .7 1 5 2 9 .5 4 4 7 5 .0 8 4 6 .7 1 5 6 0 .0 5 c u sp n u m b er l m 2 (+ = a s u 4 ) 5 7 .1 1 4 3 0 .0 1 0 3 5 .7 4 2 2 3 .1 1 3 4 4 .4 9 0 .0 9 d ef le ct in g w ri n k le l m 1 (+ = a s u 2 -3 ) 2 2 .2 9 3 0 .0 1 0 4 1 .9 3 1 2 5 .0 4 4 2 .9 7 5 0 .0 4 c 1 -c 2 c re st l m 1 (+ = a s u 1 ) 3 3 .3 1 2 0 .0 1 0 4 2 .9 3 5 1 6 .7 6 1 1 .1 9 2 8 .6 7 p ro to st y li d l m 1 (+ = a s u 2 -6 ) 0 .0 1 8 0 .0 1 5 1 1 .8 5 1 0 .0 8 6 .3 1 6 0 .0 1 0 c u sp 7 l m 1 (+ = a s u 1 -4 ) 6 .3 1 6 6 .3 1 6 1 3 .5 5 2 1 2 .5 8 2 2 .2 1 8 1 4 .3 7 ǂ d at a n o t av ai la b le f o r st u d y v e n b o l p s h t ra it ( w it h e x p re ss io n d ic h o to m y i n p ar en th es es ) p n c p a a c h i t a b l e 2 . f re q u en cy ( in % ) an d s am p le s iz e (n ) of 2 1 d en ta l tr ai ts i n s ix s ou th a m er ic a n p op u la ti on s 26 because similar levels of occurrence have been associated with european and african populations (scott and turner, 1997). moreover, frequencies of lm1 protostylid are remarkably low in all south american groups examined. however, this can be attributed to the fact that, to avoid misleading assessments due to the presence of pit-like caries on the buccal groove, i did not include the asudas grade 1 as part of the protostylid complex. although turner (1971) found the high incidence of three-rooted lm1 to be a distinctive sinodont feature, this trait was invariably absent in all samples studied. these latter results, however, could be biased given that only loose molars or root sockets lacking teeth were recorded (i.e., no radiographic analysis was conducted). mean measure of divergence intra-regional analysis pair-wise comparisons for the six south american samples using the mmd statistical program are presented in table 3. mmd values range from 0 to 0.229, with a mean of 0.054. in general, there are significant dental affinities among most of the samples examined, especially in pnc, chi and ven. the intra-regional analysis also suggests that, within the south american region, the most divergent group is psh (and bol in a lesser degree). the highest dental phenetic divergence was found between pnc vs. bol (mmd = 0.229). interestingly, pnc vs. psh and pnc vs. paa pairwise comparisons also show significantly high mmd values (mmd = 0.18 and 0.089, respectively). this was not expected since these three populations (i.e., psh, pnc and paa) came from the same country. they were geographically closest to each other relative to the ven, bol and chi samples. mean measure of divergence inter-regional analysis the present study also used the mmd to determine the degree of biological relatedness of early south americans with several world populafig. 2. examples of morphological traits present in south american upper dentitions. (a) ui2 interruption groove (indicated by a white arrow); (b) ui1-ui2 shoveling, ui1-uc tuberculum dentale and um1 carabelli’s trait (indicated by a white arrow); (c) two-rooted up3; (d) tooth socket indicating the presence of a two-rooted up3 (tooth itself is not seen); (e) ui1 winging; (f) ui1 shoveling; (g) um1 carabelli’s trait. left side depicted for figures (a-d) and (g). 27 tions exhibiting either the sinodont or sundadont dental pattern. the dental traits and breakpoints are summarized in table 4. the distance matrix based on mmd values is presented in table 5. examination of table 5, and its comparison with data from table 3, indicates that trait choice does, in some cases, influence suggested affinities between groups derived from the mmd analysis. based on the 12 dental traits listed in table 4, the highest divergence within south american populations is between psh vs. chi (mmd = 0.190; the former mmd value based on 20 dental features was 0.080). likewise, phenetic affinities between pnc vs. paa, pnc vs. bol and paa vs. chi have become either significantly higher or lower relative to those based on the 20-trait mmd analysis. on the other hand, pnc, chi and ven remain dentally closest regardless of the number of traits used for testing relationships among groups. comparisons among other world populations reveal that pnc, chi and ven exhibit the closest affinities with northern china. paradoxically, the paa sample shows significantly low mmd values with both northern china and southeast asia (mmd = 0.084 and 0.089, respectively). likewise, although the mmd inter-regional analysis indicates that bol is dentally closest to northeast siberia (mmd = 0.037), it also appears to be dentally similar to southeast asia (mmd = 0.063) and, to as lesser extent, to northern china (mmd = 0.075). all these values are, however, statistically nonsignificant. interestingly, psh is the only of the six south american groups examined in this study that clearly shows the closest relationship with southeast asians (mmd = 0.094). table 5 shows that, except for psh, the highest divergence between south americans and the other six world populations included in the mmd analysis is with pre-hispanic mexico. the degree of discordance of prehispanic mexico and south america is particularly high in the case of chi, ven and bol. this high degree of divergence is greater than would be expected if they share a recent common ancestor. however, it should be noted that relatively similar mmd values were observed for pairwise comparisons between mexico and the other world populations. thus, the unusual degree of divergence found between the psh pnc paa chi ven bol psh pnc 0.177 * paa 0.021 0.089 chi 0.080 0.000 0.012 ven 0.000 0.035 0.000 0.000 bol 0.100 0.229 0.055 0.000 0.013 * underlined mmd values are significant at p≤0.025 ɨ root number up3 not included in mmd analysis as data were not available for paa (see table 2) table 3. mean measure of divergence (mmd) for six south american samples based on 20 dental traitsɨ trait expression dichotomy shoveling ui1 asu 0-6 / (+) = asu 2-6 double shoveling ui1 asu 0-6 / (+) = asu 2-6 odontome up3-up4 asu 0-1 / (+) = asu 1 hypocone um2 asu 0-5 / (+) = asu 2-5 cusp 5 um1 asu 0-5 / (+) = asu 1-5 carabelli's trait um1 asu 0-7 / (+) = asu 2-7 enamel extension um1 asu 0-3 / (+) = asu 2-3 groove pattern lm2 asu y, x, + / (+) = asu y cusp number lm1 asu 0-6 / (+) = asu 6 cusp number lm2 asu 0-6 / (+) = asu 4 deflecting wrinkle lm1 asu 0-3 / (+) = asu 1-3 cusp 7 lm1 asu 0-4 / (+) = asu 1-4 t r a i t s h o v e lin g u i 1 2 7 / 0 7 d o u b le s h o v e lin g u i 1 2 6 / 0 6 h y p o c o n e u m 2 2 5 / 0 5 c u s p 5 u m 1 1 5 / 0 5 c a r a b e lli' s t r a it u m 1 2 7 / 0 7 e n a m e l e x t e n s io n u m 1 2 3 / 0 3 o d o n t o m e p 1 p 2 + / + ,r o o t n u m b e r u p 3 2 3 / 0 3 c u s p n u m b e r l m 1 6 / 4 6 . c u s p n u m b e r l m 2 4 / 4 6 . d e f le c t in g w r in k le l m 1 1 3 / 0 3 c u s p 7 l m 1 1 5 / 0 5 t a b l e 5 . d e n t a l t r a i t s u s e d i n i n t e r r e g i o n a l a n a l y s i s table 4. dental traits used in the inter-regional analysis 28 south american and mesoamerican samples may be an artifact of inter-observer error. discussion and conclusions this study characterized early south american dental morphology through the analysis of six preor proto-hispanic andean groups. interestingly, although the importance of discrete dental traits for reconstructing human population history is widely acknowledged, a comprehensive study of dental variation in a broad geographical distribution of south american populations has not yet been undertaken. most investigations have focused on north america, while research on south america has been scarce and narrow in scope (goaz and miller, 1966; kieser and preston, 1981; turner and bird, 1981; sutter, 2005; sutter and verano, 2007). an accurate reconstruction of early human dispersal to the new world relies on the analysis of archaeological samples without presumed european admixture. this, however, is not an easy task, as the study of archaeological material usually precludes the incorporation of big sample sizes. bad preservation, post mortem damage and excessive dental wear are additional problems faced by dental anthropologists interested in population history reconstructions. although with these caveats in mind, this study represents an initial step towards the better understanding of the origins and biological affinities of early south americans. examination of the pair-wise comparisons of the south american samples used in this study indicated a mean mmd of 0.054. this value is remarkably similar to that found by turner (1984) for native north american populations (mean mmd = 0.051). turner (1986) argued that dental morphological variation should be greater where human groups have lived the longest period of time. although bigger sample sizes are needed in order to draw stronger conclusions, the similar levels of variation found within both north and south america would suggest a rapid occupation of the continent by the first american inhabitants. the pnc, chi and ven samples appear to be dentally similar, with trait frequencies closely resembling those of major sinodont populations. the inter-regional analysis indicates that these three samples show greatest affinities with northern china. on the other hand, psh is the most divergent of the south american groups examined. interestingly, trait frequencies of this group more closely approximate those of sundadont populations from southeast asia. frequencies of occurrence of the majority of bol and paa dental traits occupy an intermediate position within the range of overlap of the sinodonty-sundadonty dichotomy. in this context, although some dental homogeneity was found among pnc, chi and ven, the ambiguous position of bol and paa does not provide enough evidence to support or reject hypothesis 1. however, the results of this investigation would falsify hypothesis 2, as south american populations do not necessarily follow the sinodont dental pattern suggested by turner (1986) and greenberg et al. (1986) for all native americans and modern northeast asians. although reported data were not big enough to directly contribute to the one-wave vs. multi-wave model conundrum, the results of this study are consistent with those derived from analyses of craniofacial variation among different world human populations (lahr, 1995; gonzález-josé et al., 2008; hubbe et al., 2011). these studies suggested that the appearance of the derived features present in modern northeast asians was a relatively recent event (ca. 7000 b.p.) and that the first migrants would have brought with them to the new world a more generalized and heterogeneous set of craniofacial and dental features (contra turner, 1986, 1990; greenberg et al., 1986). the fact that native americans do not necessarily follow a strict sinodont dental pattern was also found by haydenblit’s (1996) analysis of four pre-hispanic mexican populations. finally, the greatest similarity of pnc, chi and ven dentitions compared to the other south american groups was somewhat unexpected given the relatively ample geographic distances existing among these populations. interestingly, all three (i.e., pnc, chi and ven) are derived from lowland and/or coastal regions. furthermore, it was surprising to find that some of the highest degrees of dental divergence are between peruvian-derived populations (pnc vs. psh and pncvs. paa; see table 3). as noted, the most variable populations (those whose trait frequencies cannot always be accommodated under the sinodont pattern) are psh, paa and bol. in contrast to pnc, chi and ven, the psh, paa and bol samples are from very high altitude regions between ca. 29 t a b l e 5 . m ea n m ea su re o f d iv er g en ce ( m m d ) fo r s o u th a m er ic an a n d n o n -s ou th a m er ic an s am p le s b a se d o n 1 2 d en ta l tr ai ts . p s h p n c p a a c h i v e n b o l m e x ɨ n a m er ic aǂ e s k ǁ n e s ib er ia ‡ n c h in a₱ s e a si a¶ p s h p n c 0 .1 7 7 * p a a 0 .0 2 2 0 .0 3 9 c h i 0 .1 9 0 0 .0 0 0 0 .1 0 5 v e n 0 .0 0 2 0 .0 0 0 0 .0 0 0 0 .0 0 0 b o l 0 .1 4 1 0 .1 1 5 0 .0 5 0 0 .0 0 0 0 .0 1 8 m e x 0 .2 4 3 0 .2 7 3 0 .1 9 0 0 .4 5 6 0 .4 1 3 0 .5 0 9 n a m er ic a 0 .4 1 0 0 .0 7 7 0 .1 9 1 0 .1 7 6 0 .1 9 5 0 .1 7 3 0 .5 7 6 e s k 0 .3 4 9 0 .1 4 3 0 .1 2 4 0 .2 4 9 0 .2 3 8 0 .0 9 0 0 .4 8 8 0 .0 5 7 n e s ib er ia 0 .2 4 0 0 .2 1 5 0 .1 2 3 0 .2 9 8 0 .1 7 8 0 .0 3 7 0 .5 5 9 0 .1 6 5 0 .0 8 7 n c h in a 0 .2 2 0 0 .0 3 7 0 .0 8 4 0 .1 6 0 0 .0 8 8 0 .0 7 5 0 .3 9 6 0 .1 0 2 0 .0 8 0 0 .1 2 1 s e a si a 0 .0 9 4 0 .2 5 2 0 .0 8 9 0 .2 0 3 0 .1 4 3 0 .0 6 3 0 .3 7 0 0 .3 3 9 0 .2 1 6 0 .2 0 9 0 .1 4 6 ¶ s e a si a: s o u th ea st a si a. d at a fr o m t u rn er ( 1 9 8 4 , 1 9 8 7 , 1 9 9 0 ) * u n d er li n ed m m d v al u es a re s ig n if ic an t at p ≤ 0 .0 2 5 ɨ m e x : p re -h is p an ic m ex ic o . d at a fr o m t u rn er ( 1 9 8 4 ) an d h ay d en b li t (1 9 9 6 ) ǂ n a m er ic a: n o rt h a m er ic an i n d ia n s, e x cl u d in g n ad en e sp ea k er s. d at a fr o m t u rn er ( 1 9 8 4 , 1 9 8 6 ) ǁ e s k : e sk im o ( in u it p o p u la ti o n s) . d at a fr o m t u rn er ( 1 9 8 4 , 1 9 8 6 ) ‡ n e s ib er ia : n o rt h ea st s ib er ia . d at a fr o m t u rn er ( 1 9 8 4 , 1 9 8 7 , 1 9 9 0 ) ₱ n c h in a: n o rt h c h in am o n g o li a. d at a fr o m t u rn er ( 1 9 8 4 , 1 9 8 7 , 1 9 9 0 ) 30 3,000 and 3,800 meters above the sea level). this suggests that, regardless of geographic distance, the observed pattern of dental variation may be the result of different rates of gene flow and genetic drift operating in the lowlands and highlands. thus, while lowland and coastal regions would have favored high rates of gene flow among populations living in those areas, genetic drift would have played an important role in shaping the pattern of diversity present in highland populations. the debate of the initial peopling of the new world is far from being resolved, and many questions remain to be answered. nevertheless, this study demonstrated that neither the clovis-first nor the three-wave models for the settlement of the americas by a highly specialized sinodontmongoloid human group is sufficient to encompass the pattern of dental morphological diversity present across the continent. to move forward past hypotheses need to be reevaluated through systematic and interdisciplinary studies. this study showed that dental morphology is a key area of research towards the accomplishment of these goals. acknowledgements i would like to thank the staff of both the american museum of natural history, anthropology department (ny, usa) and the instituto nacional de cultura (chachapoyas, peru) for allowing access to their collections, without which this study would not have been possible. i am especially grateful to shara bailey for the constant guidance and feedback to improve this study. literature cited adovasio jm, pedler dr, donahue j, stuckenrath r. 1998. two decades of debate on meadowcroft rockshelter. north am 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and anthropology, illinois state university 2 department of anthropology, suny oneonta paleopathological data in sample-based bioarchaeological inquiry are a well-established adjunct to archaeological problem-solving (e.g., buikstra and beck, 2017; larsen, 2015; martin et al., 2013). although the reconstruction of extinct cultures is largely the purview of archaeology, many archaeological contexts, such as mortuary sites and salvage projects, lack the associated material culture to address basic questions about subsistence, settlement pattern, and social organization. in these circumstances, bioarchaeological data can be an effective primary archaeological problem-solving tool (e.g., armelagos, 2003; larsen, 2015; mosher et al., 2015; smith et al., 2016; stojanowski & duncan, 2015). dental caries prevalence and severity can be particularly effective as a benchmark of agricultural intensification and the dietary primacy of particular fermentable carbohydrates (e.g., caselitz, 1998; karsten et al., 2015; larsen, 1991, 2005; lubell et al., 1994; lukacs, 1992; patterson, 1986; šlaus et al., 2011; temple & larsen, 2007; turner, 1979). carious lesions are the consequence of the demineralization of tooth enamel by the metabolic processes of certain oral bacteria (e.g., streptococcus mutans) in the presence of refined carbohydrates. in the americas, the primary cariogenic carbohydrate of agricultural intensification (post ad 900 contact) is maize (zea mays) (e.g., simon, 2017; smith, 2017; vanderwarker et al., 2017), particularly the variant known as northern “flint corn” (zea mays indentata) (simon, 2017). it is commonly asserted that caries incidence rises dramatically with the adoption of maize (e.g., emerson et al., 2005; larsen, 1981; powell, 1985; watson, 2005). however, the increase is not simply a reflection of absolute carbohydrate consumption as other, likely synergistic factors (e.g., rate of attrition, hypoplastic defects, and malocclusion), affect individual vulnerability to cariogenesis. complicating the subsistence inferences, documentation of caries prevalence across the late prehistoric site samples from the contiguous united states can be variable and uneven. often this abstract the dentition from two middle mississippian period (~ad 1100-1350) site samples (gray farm [~ad 1100-1350], link/slayden [~ad 1100-1400]) from the kentucky lake reservoir of westcentral tennessee area are examined for caries prevalence by tooth type, lesion size, and crown-root location to assess whether a maize-intensive subsistence economy is evident. given the paucity of local archaeological context, comparative caries prevalence and pattern operate as a critical archaeological problem-solving tool. the middle mississippian samples are compared to a kentucky lake late woodland period (~ad 400-900) horticulturist site sample (hobbs) as well as three unequivocal maizeintensive agriculturalist site samples from the late mississippian period of east tennessee (~ad 13001550). the caries patterns (tooth type, location, size) in the gray farm sample is consistently not statistically different from the maize-intensive samples; link/slayden is consistently statistically different and resembles the caries pattern and prevalence of the hobbs sample. the adoption of maize as a primary cultigen in the kentucky lake reservoir is evidently geographically variable. this may reflect local ecological contexts or differential socio-economic contacts with neighboring mississippian economies. or, more likely, it may reflect temporal differences in mississippianization between the kentucky lake reservoir sites. *correspondence to: maria ostendorf smith1 department of sociology and anthropology illinois state university normal, illinois 61790-4660 msmith@ilstu.edu keywords: mississippian, maize, dental caries, carious lesions, tennessee 52 dental anthropology 2019 │ volume 32 │ issue 02 reflects sample preservation, as dental data are differentially available: loose teeth, in situ presence, and antemortem (alveolar resorption) and postmortem (empty sockets) tooth loss. recording can consist of the prevalence of carious individuals, the prevalence of carious teeth, prevalence of carious teeth by tooth class, and/or the application of caries correction factors. the result is often a lack of inter-site comparability. this can be interpretively problematic as the temporal transition to maizeintensive agriculture is ecologically, geographically, and socio-politically variable (emerson et al., 2005; hutchinson et al., 1998; scarry, 1993; wilson, 2017). the adoption of stable isotope analysis (i.e., c3/c4 ratios prevalence) allowed archaeologists to sidestep the shortcomings of osteological preservation and the quantitative methodology issues. however, this option is not available for many precolumbian human osteological samples in the contiguous united states as destructive analysis is not permitted.1 the intensive adoption of maize as a primary cultigen across the eastern continental united states throughout the middle and lower mississippi river valley, the lower ohio river valley, and the southeastern united states north of florida cooccurs with the most recent pre-columbian cultural horizon, the mississippian period (~ad 1000 – 1500) (bense, 2016; king, 2017; vanderwarker, 2017; wilson, 2017). the horizon reflects the most complex sociopolitical organization north of mesoamerica (bense, 2016; smith, 1990) and is archaeologically manifested by the presence of large aggregated village settlements, often palisaded, that were organized around a central plaza. the plaza, in turn, was flanked by one or more quadrilateral flat-topped mounds with variable functions (e.g., mortuary, domiciliary, temple) (dalan, 1997; kidder, 2004; king, 2001; king, 2017; lewis et al., 1998). some level of centralized authority (arguably chiefdom-level) is evident (beck, 2003; cobb, 2003; king, 2017; pauketat, 2007). the mississippian period is also characterized by a complex iconography (i.e., the “southeastern ceremonial complex” [secc] or “southeastern ceremonial exchange network” [scen]) of sociopolitical as well as cosmological meaning (knight, 2006; knight et al., 2001; muller, 1989; reilly and garber, 2007). the apex of mississippian culture occurred in the middle period (ce 1200-1400) when the hallmarks of mississippian culture are present throughout the middle and lower mississippi river valley, the lower ohio river valley, and the southeastern united states north of florida. plant domestication has a long trajectory in the pre-columbian eastern us (e.g., fritz, 1990; scarry, 2008; smith, 2006, 2011; smith and yarnell, 2009). prior to the dedicated adoption of maize, cultigens consisted of a suite of native oily (e.g., sunflower and marsh elder) and starchy seed grasses (e.g., maygrass, knotweed, lamb’s quarter, little barley) referred to as the eastern agricultural complex (eac) (scarry, 2008; smith, 2006; smith and yarnell, 2009). the transition from native grasses to maize cultivation was not temporally or geographically uniform and may have been influenced by ecological constraints or peripheral geographic location relative to the mississippian cultural heartland (e.g., fritz, 1990; smith, 2011; 2017). within this mississippian culture area, regional polities occur that differed in social complexity and the adoption of mississippian cultural elements. one of these variants, the middle cumberland culture (mcc), is physiographically concentrated in the nashville basin of central tennessee (dowd, 2008; ferguson, 1972; moore et al., 2006; smith, 1992) and extends from the cumberland river drainages between the confluence of the caney fork and cumberland rivers in the east to the confluence of the red and cumberland rivers in the west (figure 1). it has been archaeologically observed that the nashville basin had a high population density in late prehistory and mirrored the mississippian socioeconomic pattern of mound centers and agriculturalization (beahm, 2013; jolley, 1983). maize cultivation, likely intensive, is evident in mcc sites (beahm, 2013; buikstra, et al., 1988; crites, 1984). figure 1. map of west-central tennessee identifying the location of the site samples in the tennessee river valley. the valley is flanked by two highland areas: the west tennessee uplands and the western highland rim. the dashed line demarcates the western most extent of the middle cumberland culture. 53 dental anthropology 2019 │ volume 32 │ issue 02 there are numerous middle mississippian sites in the tennessee river valley west of the highland areas and beyond the western boundary of the mcc in, and adjacent to, what is now the kentucky lake reservoir. maize-intensive agriculture is ubiquitous in the late mississippian period (~ ad 1350-1550) (bense, 2016; king, 2017; vanderwarker, 2017; wilson, 2017), but geographically variable in the middle mississippian period. identifying the subsistence patterning is particularly important in the kentucky lake area because there are no late mississippian components for any site as the region was inexplicably abandoned by circa ad 1450 (bass, 1985; cobb and butler, 1992; williams, 1990). with little evaluated archaeological material culture from kentucky lake, the dental caries data from sites in this apparent cultural frontier provide critical insight into the dietary importance of maize. materials and methods the three kentucky lake reservoir sites examined for caries prevalence and patterns are physiographically located in the western valley of the lower tennessee river, which is situated between two highland areas (see figure 1). to the west, are the western tennessee uplands and to the east, the western highland rim of the nashville basin. the sites were excavated as salvage archaeological projects prior to the completion of the kentucky dam (gilbertsville, kentucky) (1938-1944). two of the west-central tennessee archaeological sites, link (40hs6) and slayden (40hs1), are located on river bluffs above the duck river, a tributary of the tennessee river, at the confluence of its tributary, the buffalo river. the sites are within twenty kilometers of the confluence of the duck river with the tennessee river. they are argued to be the same settlement context and are thus evaluated together. link/slayden was a multi-mound mississippian context dating to the early-to-middle mississippian period (~ad 1100-1350) (bass, 1985; dye, 2002, 2003; kuemin drews, 2000; lunn, 2013). the link site is the source of the duck river cache, arguably the most spectacular collection of native american stone work (i.e., circa four dozen stone maces, stone knives, stone daggers) recovered in the eastern united states (brehm, 1981; dye, 2007). the gray farm site (40sw1) is a middle mississippian multi-mound site located on the eastern bank of the tennessee river just north of the confluence of the big sandy river (bass, 1985; kuemin drews, 2001). temporally it appears to be as old as link/ slayden, but archaeological evidence (ceramics and domestic structure types) suggests it was occupied longer (bass, 1985). it is approximately 50 air kilometers north of link/slayden. the third kentucky lake reservoir site assessed for dental caries dates to the late woodland (~ad 500-900) period (kuemin drews, 2001). hobbs (40hs44) is a mound mortuary context located downstream from link/slayden on the main channel of the tennessee river (see figure 1). archaeologically it co-occurs with the cultivation of the native grasses of the eastern agricultural complex (smith and yarnell, 2009). the permanent dentition of adult burials from the kentucky lake site samples was canvassed for the presence of carious lesions. all skeletons had previously been assessed for age and sex using standard non-metric osteological criteria (e.g., buikstra and ubelaker, 1994). individuals were included in the sample if they were skeletally assessed as adults (buikstra and ubelaker, 1994) or the preserved third molars (loose or in-situ) were present as, at least, a developmentally complete crown. the teeth were examined for carious lesions which were scored by size and location on the crown (occlusal, smooth surface [e.g., interdental, buccal, lingual], and/or the cemento-enamel junction [cej]). lesions that involved adjacent teeth were attributed to both teeth. a carious lesion was recognized by a pit measuring at least 1 mm in diameter (figure 2a) with evidence of demineralization at the orifice (figure 2b, 2c) to distinguish it from pit-fissure irregularities on the occlusal and buccal surfaces. assessment was aided by a 2x-4x hand lens. carious lesions circa 4 mm in diameter were classified as medium and non-pulppenetrating lesions greater than 4 mm were classified as large. pulp exposures were included based on the likelihood that they resulted from carious lesions from the crown or cej. where preservation permitted, a necrotic tooth represented only by the roots or a pulp exposure associated with alveolar pocketing was not included (as periodontal disease could not be etiologically excluded). this exclusion did not seem to affect caries prevalence, as necrotic roots were isolated occurrences. teeth exhibiting antemortem breakage were also excluded. these were identified by sharp-edged concavities with non-demineralized surfaces with evidence of masticatory use (i.e., polish or attrition) (figure 2d, e, f). preservation ranged from fair to poor at all sites. few individuals preserved complete enough maxillae or mandibles to reliably calculate dental caries 54 dental anthropology 2019 │ volume 32 │ issue 02 prevalence by individual or to apply a caries correction factor. the present study assesses dental caries by three tooth type categories irrespective of arch or antimere: incisors and canines (i/c), premolars (pm), and molars. molars were also assessed by position in the tooth row (m1-m3). the samples were compared for sex differences within the site sample and between site samples. adults were also segregated into three age-at-death categories: young (18 to ~35 years), middle (35 to 50 years), and mature (50+ years) based on the skeletal age-at-death range provided in the computer database. a local comparative context was needed to assess whether the middle mississippian period kentucky lake samples were maize-intensive agriculturalists or whether they continued to cultivate native grasses. as no data sample is available (either published or available for research) from the middle cumberland culture or the mississippi river valley of tennessee, three unequivocal late mississippian (~1300-1450 ad) period maizeintensive agriculturalist site samples from east tennessee were utilized. the sites are also prereservoir archaeological salvage projects and are located along the tennessee river or its tributary, the little tennessee river. the little tennessee river valley samples are from the sites of toqua (40mr6) and citico (40mr7) (i.e., tellico reservoir), and the dallas (40ha1) site located along the tennessee river (i.e., chickamauga reservoir) (betsinger and smith, 2013, 2018). the data were previously collected by the authors and reflect the same collecting protocols as the kentucky lake site samples.2 the prevalence rates of caries by the three tooth types were compared utilizing the fisher’s exact test (p ≤ 0.05). intra-site comparisons were based on sex, while inter-site comparisons were made for the entire sample, for males, for females, and by age cohort. further segregating the samples into age categories by sex yielded sample sizes too small for statistical assessment (e.g., n <10). figure 2. examples of the extent of carious lesions from the link (40hs6) sample. a) burial 6 (unit 19) exhibits a pulp-penetrating carie at the cemento-enamel junction, b) the first and second molars of burial 3 (unit 21) displaying (arrows) pulp exposure, pit-fissure occlusal cavities larger than 1 mm, and a carious lesion in the buccal pit, c) and burial 3 (unit 67) illustrates a carious buccal pit. non-carious antemortem cusp breakage (sharp perimeter, no demineralization) is exemplified in d) burial 30 (unit 21) with non-carious dentin-exposing breakage exhibited in e) burial 32 (unit 21) and f) burial 38 (unit 21). 55 dental anthropology 2019 │ volume 32 │ issue 02 results caries by tooth type in the link/slayden total sample (table 1), two percent of all preserved teeth exhibit at least one carious lesion. this is the lowest frequency of the three kentucky lake samples. when assessed by tooth class, link/slayden carious teeth are restricted to the posterior dentition. over seven percent of all molars exhibit a carious lesion with the third molar the most frequently affected. however, this differential involvement is likely due to the paucity of first and second molars consequential to observed antemortem tooth loss. there are also no carious lesions in the incisiform dentition from the late woodland hobbs site sample. the proportion of carious molar teeth is also circa seven percent. the percent of caries in the hobbs premolar sample generates the only statistically significant difference between the two samples (table 2) affecting the significant difference for all dentition (p = 0.0219). the gray farm sample has the highest frequency of any carious teeth (17.3%) with caries present in all the tooth classes. gray farm has significantly higher caries prevalence for all but the third molar (5/17, 29.4%) compared to the link/ slayden sample (5/33, 15%). the relatively higher caries rates by tooth class in the hobbs sample relative to link/slayden generate fewer statistically significant differences compared to the gray farm sample. only the more frequent carious second molars in gray farm (33.3% vs 4.8%) are significantly different compared to hobbs (p = 0.0448). sex differences in caries prevalence given that females in many agriculturalist archaeological samples are likely more predisposed to dental caries (e.g., lukacs, 1996, 2008; lukacs and largaespada, 2006), each site sample was tested for table 1. caries presence, location, and severity by tooth type 1 incisors and canines are pooled, 2 smooth surface, 3 pulp exposure, 4 teeth with more than one carious lesion tooth class link/slayden all adults males females cases/n % cases/n % cases/n % caries location occl / cej / ss2 caries severity s / m / l / p ex3 i/c1 0/121 0 0/17 0 0/74 0 -- -- -- -- -- -- -- pm 0/98 0 0/21 0 0/55 0 -- -- -- -- -- -- -- m1 3/55 5.5 0/6 0 3/24 12.5 2/3 1/3 0/3 1/3 1/3 0/3 1/3 m2 2/48 4.2 0/6 0 1/15 6.6 1/2 1/2 0/2 0/2 0/2 0/2 2/2 m3 5/33 15.1 1/2 --- 2/11 18.0 2/5 2/5 1/5 2/5 1/5 0/5 2/5 all m 10/138 7.2 1/14 7.1 6/50 12.0 5/10 4/10 1/10 3/10 2/10 2/10 3/10 all dent 10/493 2.0 1/52 1.9 6/179 3.4 5/10 4/10 1/10 3/10 2/10 2/10 3/10 tooth class hobbs all adults males female cases/n % cases/n % cases/n % caries location occl / cej / ss2 caries severity s / m / l / p ex3 i/c1 0/38 0 0/8 0 0/22 0 -- -- -- -- -- -- -- pm 3/30 10.0 1/12 8.0 2/16 12.5 0/3 3/3 0/3 3/3 0/3 0/3 0/3 m1 2/16 12.5 2/4 ---0/7 0 1/2 1/2 0/2 2/2 0/2 0/2 0/2 m2 1/21 4.8 1/4 ---0/15 0 1/14 1/14 0/1 1/1 0/1 0/1 0/1 m3 1/17 5.9 1/2 ---0/6 0 1/1 0/1 0/1 1/1 0/1 0/1 0/1 all m 4/54 7.4 4/11 7.1 0/28 0 3/4 2/4 0/4 4/4 0/4 0/4 0/4 all dent 7/110 6.4 5/31 16.1 2/66 3.0 3/7 5/7 0/7 7/7 0/7 0/7 0/7 tooth class gray farm all adults males females cases/n % cases/n % cases/n % caries location occl / cej / ss2 caries severity s / m / l / p ex3 i/c1 4/48 8.3 3/12 25.0 1/21 4.8 0/4 1/4 3/4 3/4 1/4 0/4 0/4 pm 4/58 6.9 1/12 8.0 1/22 4.5 1/4 2/4 1/4 3/4 1/4 0/4 0/4 m1 10/29 34.0 2/10 20.0 1/10 10.0 3/10 3/10 4/10 8/10 2/10 0/10 0/10 m2 7/21 33.3 1/11 9.0 4/9 44.4 6/7 0/7 1/7 7/7 0/7 0/7 0/7 m3 5/17 29.4 0/4 0 2/10 20.0 4/5 0/5 1/5 5/5 0/5 0/5 0/5 all m 22/67 3.3 3/25 12.0 7/29 24.1 14/22 3/22 6/22 20/22 2/22 0/22 0/22 all dent 30/173 17.3 7/49 14.3 9/72 12.5 15/30 5/30 7/30 26/30 4/30 0/30 0/30 56 dental anthropology 2019 │ volume 32 │ issue 02 sex differences. there is an under-enumeration of males by molar type within both the link/slayden and hobbs samples and for the m3 in the gray farm sample (see table 1), therefore the between sex comparisons are restricted. there are no carious teeth in the i/c and pm categories in the link/slayden sample but the collective molar and collective dentition tests (including i/c and pm) are not significantly different by sex (see table 2). in the tests by tooth type in the gray farm comparisons, males and females are not significantly different. the hobbs sample exhibits a statistically different higher prevalence for males in the total tooth sample (16% versus 3%), undoubtedly effected by the higher male prevalence in the (small) male collective molar sample (36.4% versus 0%). in the absence of definitive differences between the sexes in caries prevalence, the samples can be pooled for statistical testing. caries prevalence compared to maize-intensive samples the total-sample comparisons of caries presence by tooth type of link/slayden with the toqua, citico, and dallas samples generated statistically significant differences for all tests except the third molar (table 3). in contrast, all the total sample compari link/slayden hobbs gray farm sex differences within samples i/c --- --- 0.1250 pm --- 1.0000 1.0000 m1 --- --- 1.0000 m2 --- --- --- m3 --- --- --- all m 1.0000 0.0040 0.3095 all dent 1.0000 0.0091 0.7904 link/slayden x hobbs link/slayden x gray farm hobbs x gr ay farm caries in the total sample i/c ----0.0059 0.1264 pm 0.0119 0.0179 0.6787 m1 0.3137 0.0009 0.1641 m2 1.0000 0.0025 0.0448 m3 0.6498 0.2768 0.1748 all m 1.0000 0.0001 0.0007 all dent 0.0219 0.0001 0.0003 sample comparisons by males i/c ---0.0602 0.2421 pm 0.3824 0.3824 1.0000 m1 --------- m2 --------- m3 --------- all m 0.1333 1.000 0.1665 all dent 0.0254 0.0281 1.0000 sample comparisons by females i/c ---0.2292 1.0000 pm 0.0582 0.2857 0.5619 m1 1.0000 1.0000 1.0000 m2 --------- m3 ---1.0000 --- all m 0.0825 0.2110 0.0104 all dent 1.0000 0.0144 0.0577 table 2. intraand interkentucky lake sample caries prevalence by tooth type 57 dental anthropology 2019 │ volume 32 │ issue 02 sons by tooth type of the gray farm sample were not significantly different (table 4). the late woodland hobbs sample was significantly different in the posterior teeth from two (dallas and toqua) of the three east tennessee mississippian samples. the number of statistical tests in the male cohort between the kentucky lake samples and the maize -intensive samples were restricted because of poor sample sizes in the male cohort. however, the congruence of the collective gray farm sample with the collective maize-intensive samples is maintained in the male sample comparisons (see table 3). the under-enumeration of males in the hobbs and link/slayden samples limits the number of teeth available to test. however, the pooled male dentitions in link/slayden are significantly different from the toqua, citico, and dallas samples. the few tests available for the hobbs sample are not significantly different for any of the maizeintensive samples. with larger samples available for the females, more tests are possible. missing only a test for m2, there are otherwise no female sample differences between gray farm and any of the maize-intensive samples. the absence of caries in the incisiform teeth and premolars in the link/ slayden sample is significantly different from all the maize-intensive samples. the lower frequency of dental caries in the first molars of link/slayden is significantly different (p = ≤ 0.05) from the citico toqua citico dallas total samples total samples total samples link/ slayden gray farm hobbs link/ slayden gray farm hobbs link/ slayden gray farm hobbs i/c 0.0001 1.0000 0.1070 0.0001 0.0649 1.0000 0.0034 0.5195 0.2444 pm 0.0001 0.4999 1.0000 0.0001 0.4514 0.0575 0.0001 0.4816 1.0000 m1 0.0001 0.6742 0.1587 0.0005 0.3728 0.3784 0.0001 1.0000 0.1499 m2 0.0004 0.6059 0.0303 0.0003 0.0318 0.6086 0.0001 0.2352 0.0084 m3 0.1273 1.0000 0.0425 0.3657 0.1267 0.5691 0.1780 1.0000 0.0449 all m 0.0001 0.4796 0.2811 0.0001 0.0015 0.2441 0.0001 0.7780 0.0001 all dent 0.0001 0.5131 0.0058 0.0001 0.0030 0.7503 0.0001 1.0000 0.0017 male samples male samples male samples i/c 0.3833 0.1145 --- 1.0000 1.0000 --- 0.6043 0.0425 --- pm 0.0512 0.6982 --- 0.2279 1.0000 --- 0.1344 1.0000 --- m1 ---0.4930 --- ---0.1947 --- ---0.2140 --- m2 ---0.2900 --- ---1.0000 --- ---0.2757 --- m3 --------- --------- --------- all m 0.1216 0.0995 0.5077 0.1980 0.4823 0.2163 0.0458 0.0938 0.7334 all dent 0.0089 0.8434 1.0000 0.0090 0.5987 0.8300 0.0033 1.0000 1.0000 female samples female samples female samples i/c 0.0182 1.0000 0.3794 0.0004 0.1534 0.4900 0.0349 1.0000 0.6075 pm 0.0319 1.0000 0.6307 0.0001 0.5374 0.0559 0.0020 0.4783 1.0000 m1 0.0782 0.7194 --- 0.0526 0.0991 --- 0.0160 0.0762 --- m2 0.1137 ---0.0199 0.1903 ---0.2507 0.0034 ---0.0006 m3 0.7201 0.7189 --- 1.0000 0.3330 --- 0.7089 0.7127 --- all m 0.0017 0.6690 0.0002 0.0219 0.0004 0.8287 0.0045 0.1448 0.0001 all dent 0.0001 0.4142 0.0112 0.0001 0.0001 0.1247 0.0001 0.1925 0.0004 table 3. caries prevalence in the kentucky lake samples compared to maize-intensive samples 58 dental anthropology 2019 │ volume 32 │ issue 02 and dallas samples, but not for the toqua sample (p = 0.07194). the caries prevalence for females in the link/slayden samples for m2 and m3 are only significantly different for m2 in the dallas sample. however, the pooled molar sample indicates that the fewer carious teeth in the link/slayden sample is significantly different from all of the maize intensive samples. in general, the tests for gray farm reveal a similar pattern of caries prevalence compared to toqua, citico, and dallas. in contrast, the link/ slayden sample is significantly different from the same samples. the late woodland hobbs sample, collectedly and segregated by sex, exhibits caries prevalence congruence with the citico sample. hobbs does have a lower case prevalence of caries in the posterior teeth when compared to the toqua and dallas samples. caries in kentucky lake by location and lesion size inter-sample comparisons are limited to the posterior teeth as link/slayden and hobbs have no carious i/c dentition (see table 4). the most common locations for carious lesions are the occlusal surfaces followed by the cej. smooth surface caries, that is, those that occur buccolingually and mesiodistally are infrequent and most often occur in a buccal pit (e.g., see figure 2b, c). there is no statistically significant difference among the kentucky lake sites for crown/cej location of carious lesions. lesion size in the four carious molars from the hobbs sample are all small and there are no cases of pulp exposure. the larger samples of link/slayden and gray farm (see table 4) generated statistically significant differences in the prevalence of small diameter caries and pulp exposures. the trend is toward larger size carious lesions in the link/ link/slayden x hobbs link/slayden x gray farm hobbs x gray farm occlusal cej ss1 occlusal cej ss1 occlusal cej ss1 all m 0.5804 1.000 --- 0.6993 0.1655 0.3871 1.0000 0.5633 --- all m s m l p ex2 0.0699 1.0000 1.0000 0.5055 s m l p ex2 0.0010 0.5717 0.0907 0.0242 s m l p ex2 1.0000 1.000 --- --- toqua link/slayden gray farm hobbs occlusal cej ss1 occlusal cej ss1 occlusal cej ss1 all m 0.4997 1.0000 0.6885 0.0183 0.0092 0.5791 0.1404 1.0000 0.5832 all m s m l p ex2 1.0000 1.0000 0.6183 1.0000 s m l p ex2 <0.0001 0.3754 0.1356 0.0003 s m l p ex2 0.0158 1.0000 1.0000 0.3033 citico link/slayden gray farm hobbs occlusal cej ss1 occlusal cej ss1 occlusal cej ss1 all m 0.7558 0.2425 0.6933 0.5004 0.5771 0.5997 0.6303 0.2229 0.5765 s m l p ex2 s m l p ex2 s m l p ex2 all m 0.0978 1.0000 0.3481 0.1185 0.0039 0.3779 0.1348 0.1348 0.1537 1.0000 1.0000 1.0000 dallas link/slayden gray farm hobbs occlusal cej ss1 occlusal cej ss1 occlusal cej ss1 all m 0.5008 0.7239 1.0000 1.0000 0.1213 0.1121 1.0000 0.5906 1.0000 s m l p ex2 s m l p ex2 s m l p ex2 all m 0.1823 1.0000 0.1737 0.4472 0.0029 0.3615 0.6030 0.0135 0.1383 1.0000 1.0000 0.5818 table 4. comparison of site samples by caries location and severity 1 smooth surface, 2 pulp exposure 59 dental anthropology 2019 │ volume 32 │ issue 02 slayden sample and smaller size caries in gray farm. lesion size and location compared to maize-intensive samples the comparisons for location of carious lesions on the tooth appear to not distinguish a maizeintensive diet in any patterned way. locations for link/slayden and hobbs do not differ from the toqua, citico, or dallas samples (see table 4). gray farm distinguishes from toqua by having more occlusal relative to cej dental caries. lesion size also does seem to discriminate the maize-intensive diet; neither link/slayden nor hobbs differ from citico or dallas. the hobbs sample differs in the proportion of small lesions from toqua, but the prevalence difference in the expression of small lesions in hobbs is likely an issue of sample size (4/4, 100%). the almost exclusive expression of dental caries as small lesions and the absence of pulp exposures (see table 1) does distinguish gray farm from all three maize-intensive samples, as well as link/slayden. age-at-death differences in caries prevalence among kentucky lake samples the paucity of burials classified as mature (50+ years of age) meant that age-at-death comparisons are restricted to the young (< 35 years) and middle age (35-50 years) cohorts. there are no carious teeth in the young adult samples of hobbs (0/21) and link/slayden (0/65). whereas 12.5% of the dentition (9/72) in the gray farm sample are carious. the prevalence difference is statistically significant between link/slayden and gray farm (table 5). all of the carious teeth identified for the hobbs sample belonged to ageable adults and fall into the middle age-at-death category (7/57, 12.3%). only four carious teeth are ageable in the link/slayden sample and reflect 8.7 percent (4/46) of the middle age cohort. hobbs and link/slayden are not significantly different from each other (p=0.7506). the larger proportion of carious teeth in the gray farm sample (6/31, 19.3%) is not statistically different either from link/slayden or hobbs (see table 5). given that the preponderance of carious teeth are molars, the molar teeth are compared by age-at -death. in the young age-at-death category, the link/slayden absence of caries (0/27) is significantly different from the gray farm sample (7/37, 18.9%) (p=0.0125) but the small sample of molars in the hobbs sample (0/7) was not significantly different from gray farm or link/slayden (see table 5). in the middle age-at-death category, link/slayden (4/21, 19%), hobbs (4/23, 17.4%), and gray farm (1/10, 10%) are not significantly different from each other (see table 5). link/slayden x hobbs link/slayden x gray farm hobbs x gray farm young middle young middle young middle all teeth --- 0.7506 0.0033 0.1891 0.2010 0.5304 all molars 1.0000 1.0000 0.0125 1.0000 0.3126 1.0000 toqua link/slayden gray farm hobbs young middle young middle young middle all teeth 0.0096 0.0806 0.1830 1.0000 0.3989 0.2221 all molars 0.0174 0.2279 0.4490 0.1735 0.5988 0.1618 citico link/slayden gray farm hobbs young middle young middle young middle all teeth 0.0001 0.1582 0.8579 0.8078 0.0979 0.4638 all molars 0.0011 0.6095 0.8285 0.4614 0.2020 0.4610 dallas link/slayden gray farm hobbs young middle young middle young middle all teeth <0.0001 0.2620 0.5971 0.6086 0.0561 0.6827 all molars 0.0002 0.7757 0.3989 0.4433 0.1073 0.5824 table 5. comparison of site samples by age at death 60 dental anthropology 2019 │ volume 32 │ issue 02 age-at-death differences in caries prevalence compared to maize-intensive samples although link/slayden is a middle mississippian site sample, it has consistently statistically significant lower caries prevalence in the young age-atdeath category compared to toqua, citico, and dallas. antithetically, gray farm is statistically similar to all three. hobbs does not differ from toqua, but does for dallas, and for citico at a lower level of statistical reliability (p = ≤0.10). all samples are similar in the middle age category (see table 5). age-at-death difference for size and location of caries the preponderance of carious molars in the ageable kentucky lake sample (n=17) are found on the occlusal surface (14/17). the absence of carious teeth in the young age-at-death category of link/ slayden and hobbs means that no comparisons could be made among the kentucky lake samples. in the middle age-at-death category, there are nine molars in the collective sample. the molars in hobbs and link/slayden have the same proportion of occlusal to cervical caries: three-to-one; the gray farm site has a single molar with an occlusal carious lesion. there is a subtle difference between the molars of hobbs and link/slayden in the middle age-at-death category. all four of the lesions on the molars in the hobbs sample are small in size while two of the occlusal carious lesions in the link/slayden sample are medium-sized. link/ slayden also exhibits the only ageable carious lesion (at the cej) with pulp exposure. the absence of a statistically valid sample in the kentucky lake samples negated comparisons with the maizeintensive samples. discussion the archaeological context the bioarchaeological co-association of the intensive cultivation of specific cariogenic carbohydrates with dental caries prevalence (i.e., number of carious teeth) greater than 10 percent is commonly reported world-wide (e.g., caselitz, 1998; karsten et al., 2015; larsen, 1991, 2005; lubell et al., 1994; lukacs, 1992; patterson, 1986; šlaus et al., 2011; temple and larsen, 2007; turner, 1979) as well as in the late prehistoric contiguous united states (e.g., emerson et al., 2005; larsen, 1981; powell, 1985; watson, 2005). the utility of dental caries to flag agricultural intensification and/or the cultivation of particular cariogenic carbohydrates is particularly critical in archaeological contexts where material culture is wanting. the mississippian sites of the kentucky lake reservoir are located in a cultural frontier between the middle cumberland culture of the nashville basin and the various mississippian period phases of the mississippi river watershed located west of the west tennessee uplands (see figure 1) (see mainfort, 1996; mainfort and moore, 1998; smith, 1990). the socioeconomic context of the kentucky lake mississippian sites is poorly understood, as are the geographically adjacent late prehistoric cultures from the mississippi river watershed of west tennessee. the mississippi river valley (mrv) archaeological contexts are frequently compromised by historic period development (e.g., cultivation, urbanization, transportation [railroad and highway construction]), major changes in the meander pattern of the mississippi river, and, unfortunately, looting (mainfort and moore, 1998). to date, much of the late prehistoric mrv archaeological assessment centers on ceramic patterns and their geographic distributions. however, there is archaeobotanical evidence of maize at the chucalissa site (40sy1) (ad 1250-1500) located in the south-western corner of the state of tennessee near the present-day city of memphis (smith, 1990). the general paucity of bioarchaeological data in the mississippi river valley limits comparisons with the kentucky lake samples to all but the most well-known middle-tolate mississippian period site of chucalissa (mcnutt et al., 2012). dental caries data for chucalissa are restricted to the number of carious teeth (271/1386, 19.6%) (robinson, 1976), which compares favorably (p = 0.7465) with the gray farm site sample (30/173, 17.3%), and contrasts with link/sladen (p = 0.0001) and hobbs (p = 0.0041). whether maize presence as a staple crop in the mississippi river valley influenced a diffusion toward, at least, gray farm, is problematic. there is scarce evidence of mississippian occupation east of the mississippi river floodplain in the west tennessee uplands (mainfort, 1996; smith, 1990) suggesting little or no cultural influence from the mississippi river valley. indeed, according to the seminal archaeological overview of mississippian sites in the kentucky lake reservoir by quentin bass, mississippianization was an in situ development rather than culture-bearing in-migration(s) of populations into the area (1985:93). in contrast, the mortuary pattern of interment characterized by the lining of the grave pit with stone slabs (“stone box burials”) associated with the middle cumberland culture (ad 1250-1450, 61 dental anthropology 2019 │ volume 32 │ issue 02 thruston phase) of the nashville basin (figure 1) (dowd, 2008; ferguson, 1972) frequently occurs in kentucky lake reservoir mississippian sites (bass, 1985; wamsley, 2018). relative to the present study, the mortuary pattern of the gray farm site includes stone boxes as well as secondary interments of charnel house burials, whereas the entirety of the mortuary treatment at link/slayden is stone box (bass, 1985; wamsley, 2018). predictably, no stone box interments occur at the late woodland hobbs site (kuemin drews, 2000; wamsley, 2018). unfortunately, no caries data are available from middle cumberland culture sites. the socioeconomic circumstance of the kentucky lake samples is temporally important, as no late mississippian occupation (i.e., ad 1400-1600) is evident (bass, 1985). this pre-columbian abandonment of the lower tennessee river valley is part of a larger post-ad 1450 regional depopulation phenomenon centered in the lower ohio river valley known as “the vacant quarter” (cobb and butler, 2002; williams, 1990). the abandonment is not well understood (cobb and butler, 2002; williams, 1990), but may very well co-associate with precipitation corollaries of major climate change (i.e., “little ice age,” circa ad 1400-1850) (e.g., anderson, 2001; meeks and anderson, 2013; stinchcomb et al., 2011). the maize-intensive patterns the frequency of carious teeth by tooth type and caries prevalence segregated by age-at-death in the gray farm sample compared to the unequivocal maize-intensive samples from east tennessee (e.g., chapman, 2014; polhemus, 1987) strongly suggests that it reflects a maize-intensive subsistence strategy. the strategic location of the gray farm site straddling the cumberland and tennessee river valleys (see figure 1) may have eco-culturally influenced the adoption of maize as a primary cultigen. that is, the gray farm site is located downstream from the communities of the middle cumberland culture who are archaeologically identified as maize intensive (e.g., beahm, 2013; crites, 1984). a singularity of the gray farm dental caries pattern occurs in lesion size and location relative to the link/slayden sample as well as the three late mississippian sites (table 4). gray farm has an over enumeration of small carious lesions and an under-representation of pulp exposures. a number of variables could explain this finding. it could suggest a qualitatively different cariogenic food consumption pattern. that is, processing and/or consumption of maize that limits the metabolic activity of the oral bacteria. or, more likely, a biased dental sample relative to antemortem tooth loss. the proportion of molar teeth out of the total tooth sample available for study is consistent across the age-at-death categories for hobbs (7/28, 33% versus 23/57, 40%) and link/slayden (27/67, 40.3% versus 19/44, 43.2%). however, in the young age-at-death category for gray farm, over 50 percent of the dental sample is composed of molars (37/71); in the middle age-at-death category, the proportion is reduced to a third (10/30). given that neither hobbs nor link/slayden register any carious lesions among the young adults, the retention of teeth with more advanced lesions in middle age is plausible. whereas, cariogenesis initiated in (at least) early adulthood would inevitably progress to necrosis and tooth loss by middle age. a directed examination of antemortem tooth loss would corroborate this. the link/slayden patterns the archaeological context of the link/slayden site sample indicates a mississippianized settlement pattern of a multiple-mound aggregated village (bass, 1985), but it is clear that the subsistence pattern is different from gray farm and the east tennessee late mississippian sites. the congruence of many of the dental caries comparisons with the late woodland hobbs site and significant difference of the link/slayden sample with the maizeintensive samples affirms this. interpretively important, the pattern and prevalence of dental caries is not consistent with pre-agricultural data. the total tooth sample caries prevalence for three late archaic hunter-gatherer samples from this reservoir is 2.7 percent (93/3414) (smith, 1982) and is significantly different from hobbs (p=0.0352) and link/slayden (p=0.0316). the location of carious lesions on all teeth in the archaic sample is almost exclusively at the cej (53/58, 91.4%), in contrast to hobbs where half of all carious lesions are on the occlusal surface. the congruence of link/slayden and hobbs in caries prevalence as well as the similarity of certain caries frequencies of hobbs with the maizeintensive samples is consistent with the history of plant domestication in the kentucky lake reservoir area. that is, west-central tennessee is part of the core area within which the eastern agricultural complex developed that was well-established by the late woodland period (e.g., smith, 2006, 2011; smith and yarnell, 2009). in particular, archaeobotanical data from sites upstream in the duck river 62 dental anthropology 2019 │ volume 32 │ issue 02 valley (normandy reservoir) indicate there was a shift in the late woodland from the ceremonial use of maize to dietary use (cobb and faulkner, 1978; shea, 1977). however, an elevation in caries prevalence does not necessarily indicate a shifting reliance toward maize as high prevalence has been observed in woodland contexts pre-dating the introduction of maize (e.g., alfono-durrity et al., 2014; rose and marks, 1985; rose et al., 1991). although the location of link/slayden may be geographically remote relative to the core area of the maize-intensive mcc, it is more likely that the site sample is temporally earlier than gray farm. a recent assessment of the ceramics at the slayden site suggests a primary occupation at the earlier end of the temporal spectrum (~ ad 1100-1200) (lunn, 2013), implying that maize-intensive agriculture, and perhaps the primary occupation of gray farm, post-dated circa ad 1200 in the kentucky lake reservoir area. dental caries as an archaeological problem-solving tool. the progressive nature of carious lesions ultimately results in tooth necrosis and exfoliation. the geometry and length of time particular teeth are in occlusion certainly affect pathogenesis and vulnerability. however, the process is not simply linear as many intrinsic (e.g., general health, hypoplastic defects, attrition, periodontal disease, pregnancy/ lactation) and extrinsic (e.g., food processing, food preparation) factors are involved. in short, dental caries is not simply a proxy for the dietary reliance of one or another fermentable carbohydrate. however, as the kentucky lake samples illustrate, the complexities of cariogenesis can be modulated to address particular archaeological questions despite the analytical constraints imposed by poor preservation and small sample size. the results of the present study suggest that maize-intensive agriculture temporally occurred in the middle mississippian period (~ ad 1100-1350) of the kentucky lake reservoir area of west-central tennessee postdating the primary occupation of the link/sladen sites (~ ad 1200). all mississippian period occupation of west-central tennessee terminated by ~ ad 1450. endnotes 1 the research protocols of the osteoarchaeological samples currently curated by the frank h. mcclung museum, inclusive of the samples in this study, are not eligible for any form of destructive analysis. 2 in accordance with nagpra regulations, the osteoarchaeological samples currently curated by the frank h. mcclung museum are no longer eligible for research purposes pending repatriation and reburial. acknowledgements the authors would like to thank the staff of the frank h. mcclung museum for our long-standing access to the collections. in particular, we would like to thank dr. jefferson chapman (museum director, retired) and dr. lynne p. sullivan (curator of collections, retired). references alfonso-durruty, m.p., bauder, j., and giles, b. (2014). dental pathologies and diet in the middle woodland burials from helena crossing, arkansas. north american archaeologist, 35(1), 87-108. anderson, d.g. (2001). climate and culture change in prehistoric and early historic eastern north america. archaeology of eastern north america, 29, 143-186. armelagos, g.j. (2003). bioarchaeology as anthropology. archeological papers of the american anthropological association, 13(1), 27-40. beahm, e.l. (2013). mississippian polities in the middle cumberland region of tennessee. (phd thesis). university of georgia, athens, ga. bass, q.r., ii. (1985). sociopolitical and economic aspects of the mississippian occupation in the lower tennessee river valley. manuscript on file, department of sociology and anthropology, middle tennessee state university, murfreesboro. beck jr., r.a. (2003). consolidation and hierarchy: chiefdom variability in the mississippian southeast. american antiquity, 68(4), 641-661. bense, j.a. 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(1990). the vacant quarter and other late events in the lower valley. in d.h. dye, & c.a. cox, (eds.), towns and temples along the mississipppi (pp. 170-180). tuscaloosa: university of alabama press. wilson, g. d. (2017). mississippian beginnings. gainesville: university press of florida. drusini and swindler 2009.1 33 three-rooted mandibular first molars were, as far as we know, first described in england by a. e. taylor (1899). since then, investigators have reported 3rm1 in various frequencies in human populations, and it was noticed that 3rm1 was higher in most asian populations (tratman, 1938, 1950; pederson, 1949; turner, 1971; loh, 1990; ming gene tu et al., 2007). in a worldwide survey of 11,318 individuals from 286 prehistoric skeletal and recent populations, turner and benjamin (n.d.) found 3rm1 most common in asian and asian-derived populations, especially in the arctic and north asian populations (ca. 25-30%) and least common (ca 1%) in european and african groups. it should be noted, however, that their survey included only one sample of africans south of the sahara. in polynesia, the average is about 8.5% while the world average is approximately 10%. this paper deals with two teeth samples, one from polynesia (easter island) and one from peru: the aim of the study is to offer a contribution concerning the three-rooted mandibular first molars frequency and distribution. easter island is one of the world’s most isolated inhabited islands. human penetration into the pacific commenced about 60,000 to 45,000 years ago when humans reached australia and crossed the land bridge connecting queensland australia to new guinea (green, 1991). easter island (rapa nui; fig. 1) is in an extreme windward position as the easternmost of some 287 islands forming the cultural entity known as polynesia. easter island has an area of only 64 square miles and is rather triangular in shape. it is situated in the southern hemisphere at 27° 9’ south latitude and 109° 26’ west longitude, about 2,300 miles west of chile and some 1,400 miles east of pitcairn, the nearest inhabited island. the original easter islanders are believed to have been polynesians ultimately derived from asia who spoke a austronesian language, specifically an eastern polynesian dialect related to hawaiian and marquesan. indeed, captain james cook recognized that the easter islanders spoke the polynesian language when he visited the island in 1774. human penetration into the pacific had commenced by about 60,000 to 50,000 years ago when humans reached australia, and it appears that new guinea has been occupied for at least 40,000 years. many islands of the western pacific (near oceania), however, have been inhabited less than 5,000 years while those in the central and eastern pacific (remote oceania) have been occupied for less than a 1,000 years. it now appears that the polynesian islands were populated by what is called the ancestral polynesian society, which, in turn, was part of the eastern division frequency and variation of three-rooted lower first permanent molars in precontact easter islanders and in pre-conquest peruvians andrea g. drusini1* and daris r. swindler2 1university of padova, italy and 2university of washington, seattle, washington abstract the purpose of this study was to evaluate the prevalence of mandibular first molars featuring a distolingual root in two archeological collections. a total of 172 teeth from pre-contact easter islanders and 281 teeth from three pre-conquest peruvian sites were examined looking for the presence of three-rooted lower first permanent molars (3rlm1). the easter island teeth were recovered during the ahu tongariki excavation project 1993-2001: we identified 70 m1s, 62 m2s and 40 m3s. the sample contained 20 lower molars with an extra root, meaning that there is 29% with 3rlm1. the peruvian teeth are from three archeological sites: nasca (proyecto nasca, n = 100), arequipa (proyecto condesuyos, n = 28), and tablada de lurín (proyecto loma de lesix, n = 153). we found 8% of 3rlm1 at nasca, 1.2% at tablada de lurín, and 9% at condesuyos (total frequency = 6%). the percentage of 3rlm1 in easter island, very high compared to the whole polynesia and the peruvian sample, shows the effect of a genetic bottleneck (accidental reduction of a population), which the settlers went through as they reached the island they named rapa nui. we conclude that founder effect and genetic drift have played an important role in regulating the past and present mosaic distribution of 3rlm1 in insular populations. dental anthropology 2009;22(2):1-6. *correspondence to: andrea g. drusini, department of medical-diagnostic sciences and special therapies, university of padova via giustiniani, 2, italy e-mail: andrea.drusini@gmail.com 34 a.g. drusini and d.r. swindler of the lapita cultural complex (kirch, 1984; van tilburg, 1994). there is good evidence that these austronesian speaking people had started moving out of southeast asia by about 3,000 bc, and interestingly, there is still a genetic link (deletion of a short section of the dna in the mitochondria, or mtdna) between the polynesians of today and southeast asian populations (jones, 1994). the nucleus of the ancestral polynesian society was settled in the fiji-samoa-tonga region of western polynesia by about 1,500 bc. from here the more eastern polynesian islands were gradually colonized. easter island, the easternmost of the islands of polynesia, was settled near the end of the first millennium ad, probably between 400 and 800 ad (van tilburg, 1994; see also bellwood 1987; bahn, 1993; bahn and flenley, 1992). finney (1993) has suggested three possible settlement routes based on seasonal patterns of winds, currents, and weather conditions. route 1 is from the marquesas and would have required an el niño with westerly winds. route 2 is from the tuamotus/mangareva islands and would have been undertaken during a period of winter westerlies. route 3 is the most southerly route and comes through the australs via rapa to easter island. (note: westerlies are more common below 30° south latitude). it is not certain which of these routes was used or, in addition, whether there was a single or multiple migrations. van tilburg (1994) says that some easter island traditions suggest two early migrations but there is no indication as to the amount of time separating them. rapa nui tradition, although undoubtedly limited in its usefulness, states that there were probably two canoes carrying the original settlers with anywhere from 25 to 100 people aboard (van tilburg, 1994). it is also speculated that the party was composed of related individuals of various ranks and abilities and that they landed in the vicinity of anakena on the north central coast of easter island, probably sometime between 600 and 800 ad (van tilburg, 1994). this pattern of migration has probably characterized the peopling of the pacific islands for the last 5,000 years, i.e., relatively small groups of individual representing various degrees of genetic relationships, particularly in polynesia. where descent-groups are never completely exogamous, genetic affiliations may have been rather close among the members of a migrating group. of course, all voyages were unplanned for there were certainly accidental, unintentional migrations of individuals blown into unknown seas who happened to land on an island with only their genomes. such migration patterns are ideal for the operation of the founder effect, genetic bottlenecks, and genetic drift. the percentage of 3rlm1 in easter island, very high compared to the whole of polynesia and our peruvian sample, shows the effect of a genetic bottleneck (accidental reduction of a population), which the settlers went through as they reached the island they named rapa nui. founder effect fig. 1. easter island located at an extreme windward position in the pacific. 35 and genetic drift seem to have played an important role in regulating the past and present mosaic distribution of 3rlm1 in insular populations. materials and methods in 1993, during the ahu tongariki excavation directed by claudio critino and co-directed by giuseppe orefici, the molars that form the basis of this investigation were collected (orefici and drusini, 1993). the ahu tongariki is situated on the southeastern coast of the island. the human skeletal remains of the tongariki 14548 site were found scattered in an area of some 5,000 square meters. the skeletons were mostly incomplete and fragmented, the bone tissue was generally dry and brittle, and the in situ physicochemical erosion had given the periosteal surface a heavily weathered appearance. only the teeth were in a fairly good condition. the bone assemblage was always related to collective secondary burials of pre-contact islanders (before 1,722 according to preliminary c14 dating). since the reconstruction of individual skeletal complexes was impossible, the analysis was performed on the isolated bones and teeth. while examining these teeth we noticed that several of the lower molars possessed three roots rather than the usual two roots. in view of the prevalence of threerooted lower first permanent molars (3rm1) in asian populations we thought it would be of anthropological interest to review the pattern of 3rmls in the pacific islands and determine if there is a west-to-east cline in their distribution, and attempt an explanation for the rather high incidence of 3rmls in pre-contact easter islanders. human lower molars usually have two roots, one mesially and one distally placed transversely to the mesiodistal length of the tooth crown. the roots of the second and third molars are more variable in length and inclination than those of the first molar. additionally, the roots of the second and third molars may fuse together, especially those of the third molar, which may also have more than two roots. crown size, morphology, contact areas, and root anatomy were used in identifying the molars. there were 172 permanent lower molars consisting of ml = 70, m2 = 62, and m3 = 40. we tried to be as careful and accurate as possible in identifying the lower molars as to m1, m2 or m3 but some misidentifications are always possible when dealing with isolated teeth, especially between m1 and m2. the second sample of teeth belongs to three archeological sites of peru: nasca, south coast of peru (proyecto nasca, n = 100), arequipa (proyecto condesuyos, n = 28), and tablada de lurín (proyecto loma de lesix, n = 153). as far as the nasca project is concerned, the study was based on skeletons and mummies belonging to 582 individuals excavated at sites of pueblo viejo, cahuachi, estaqueria and atarco in the nasca valley, south coast of peru. archaeological evidence distinguishes three cultural phases: nasca (400 bc-550 ad), wari (600-1100 ad) and chincha (11001412 ad). since the chincha human remains were too exiguous (27 individuals), only nasca and wari were considered. for the nasca population, sex ratio was 113 men to 100 women (53% males); for the wari population, sex ratio was 117 men to 100 women (54% males). life tables with zero growth and with a natural increase of 2.5% per year were created. paleodemographic data show that first infancy was a critical age for survival: considering a natural increase of 2.5% per year, mortality between birth and 5 years was 22.4% for nasca and 25.1% for wari. infant mortality rate was 33‰ for nasca and 105‰ for wari. death percentages in all the age groups increased from nasca to wari phase. the paleodemographic study of the nasca valley skeletal populations confirmed the archaeological hypothesis of worse conditions of the wari population in comparison with the previous nasca people (drusini et al., 2001). all teeth belonging to the andes (proyecto condesuyos, tablada de lurín (proyecto loma de lesix) were stored in the arequipa university museum. results and discussion we have identified 20 lower first permanent molars with supernumerary distolingual third roots (3rm1) in the easter island sample. in the peruvian sample, we found 7.8% of 3rlm1 at nasca, 1.2% at tablada de lurin, and 9% at condesuyos. supernumerary distolingual roots can occur on any of the three lower permanent molars, but they are much more common on m1 than on m3, and appear more frequently on these two molars than on m2 (tratman, 1938, 1950; pedersen, 1949; turner, 1971; loh, 1990); according to all investigators, it is extremely rare on m2. the distolingual root also occurs in low frequency on the deciduous first and second molars (tratman, 1938; jørgensen, 1956): tratman (1950) says that if it occurs on dm2 it may be expected on m1. there are no deciduous molars in the present sample. of all lower molars, 3rm1 is present on m1 in much greater frequency than on m2 or m3, which led turner (1971:233) to suggest that the permanent first molar is the location for a “field-affecting gene(s)” controlling the development of the third root. to our knowledge, there is no study of the mode of inheritance of 3rm1 but because of its diachronic and population variation, turner and benjamin (n.d.) suggest that there is a “substantial genetic component in occurrence and expression.” the incidence of the distolingual root on m1 in the sexes as well as its presence on the left or right side is variable in the populations investigated to date (tratman, 1938, 1950; turner, 1971; turner and benjamin, n.d.; loh, 1990). moreover, some studies suggest it is a sexlinked dominant character (tratman, 1938; curzon and three-rooted m1 in easter islanders 36 curzon, 1971; hochstetter, 1971), while others claim that there is no sex predilection (walker and quackenbush, 1985; loh, 1990). the third root originates from the lingual side of the distal root below the cervical border and appears to be a true supernumerary root in the easter island sample, which is in accord with tratman (1938, 1950) and turner’s (1971) findings regarding the development of the distolingual root. the third root tends to be slender, somewhat conical in shape, divergent, and usually curved at the apical end towards the longer distal root; it is rarely as long as the distal root, although it varies in length and form. according to tratman (1950) in his asian sample, the distolingual root is only present on m1 when there are five cusps. turner (1971) does not mention the number of cusps present on 3rmls. in the easter island sample there is one 3rm1 with only four cusps. when the extra root is present on m3 there may be a reduction in the number of cusps, however the four cusped three-rooted molar just mentioned cannot be a third molar since there are two well formed contact areas on the mesial and distal surfaces of the crown. the extra root rarely appears on m2 but when it does, the crown is well formed and the fifth cusp is well developed. the precontact easter island sample contained 20 lower molars with an extra root. as mentioned, we identified 70 mls, 62 m2s and 40 m3s. this equates to 29% with 3rm1. if we add m2s to m1s the figure drops to 15% and if we add m3s to m1s it is 18%. these are all high percentages for polynesia, and we believe the more correct figure is around 29%. it is obvious that precontact easter islanders, based on the present sample, had a high incidence for polynesia of 3rm1s. the 29% frequency for 3rm1 is considerably beyond the range for polynesia except the sample of easter island skulls (of uncertain antiquity) that turner and benjamin (n.d.) studied, which had 21.8% 3rm1. it appears that easter islanders had, and still have, one of the highest frequencies of 3rm1 of all polynesian populations studied to date. the percentages of 3rm1 frequencies shown in fig. 2 for the major cultural areas in the pacific are the averages from turner and benjamin (n.d.). within each of these areas the percentages for several different islands are shown and unfortunately, there are still many gaps in our information regarding the incidence of 3rm1s for many of the islands: there appears to be no west-to-east cline in the distribution of 3rm1. rather, the frequencies are variable from island to island and tend to support the thesis proposed here of the importance of the founder principle and its effect on subsequent generations of new populations with few colonizers. in southern china and southeast asia, the average frequency of 3rm1 is 10 to 15%, although in historic samples from sumatra and java the frequencies are 23% and 16%, respectively. in australia, the average is 10% and represents samples from various parts of the continent. in micronesia (3%) and melanesia (3%) the condition is virtually absent, in fact, it has not been found in new guinea but is present in nearby new britain (5%). in fiji, the most easterly fig. 2. mean and range percentage of 3-rooted lower first molars (modified from turner and benjamin, n.d.). a.g. drusini and d.r. swindler mid-east 37 group of islands in melanesia, 3rmls have the highest incidence in all of melanesia, about 10%. this higher frequency may be associated with the stronger ethnic, cultural, and linguistic concordance between fiji and polynesia. the three-rooted lower first permanent molars are found in a montage of frequencies in polynesia. the trait is apparently absent on some islands (samoa, gambier, new zealand/chatham islands, and the tuamotu islands [all historic samples], and a late prehistoric sample from the marquesas islands). on tahiti (historic) it is 10%, mokapu (prehistoric) it is 12%, society islands (historic) it is 8%, cook islands (historic) it is 9%, and in the loyalty islands (historic) it is 7%. in a second sample of prehistoric-to-recent marquesans, turner and benjamin (n.d.) report an incidence of 2.7%, while on easter island (uncertain of antiquity) it is 21.8%. it is interesting to note that a relatively high incidence of 3rm1—comparable to easter island—is found routinely in the arctic (average = 30%) and northern asia (average = 25%). in several of the indigenous populations of both north and south america frequencies ranging into the teens and low twenties are present even though the averages are 8 and 7% for the two regions. it seems likely that the discovery of easter island was an accidental event from which return voyages were unlikely (houghton, 1996). such migration patterns are ideal for the operations of founder effect, genetic bottlenecks, and genetic drift. it is well known that such random factors can produce alteration of gene frequencies, especially in small populations. also, it was not necessary for such small groups to have differed a great deal from the larger populations from which they became detached because when a new closed population is formed it can develop a unique genetic system of its own. once established these genetic systems tend to persist. because of this type of population deployment throughout both near and remote oceania, there is the present mosaic pattern of genetic complexes, for example the variable incidence of 3rm1 or the variation of haplotype b, we find represented today in the pacific. conclusion except for the continent of australia and the island of new guinea, the pacific islands only started to be occupied some 5,000 years ago; some of the more easterly polynesian islands little more than a 1,000 years ago. it is generally agreed that the major direction of migration has been from west to east, although there have been dissenting views from time to time (heyerdahl, 1952; bellwood, 1987; terrell, 1990; irwin, 1994). the mosaic distribution of 3rmls in the pacific islands is, in our opinion, the result of many genetic bottlenecks, which the settlers went through as they crossed the pacific ocean. the survivors of a bottleneck may have a very different genetic composition from the population prior to the bottleneck, and in turn may become the settlers (founder effect) on another island. such chance events result in genetic drift and have undoubtedly played important roles in regulating the past and present mosaic distribution of 3rmls in these insular populations, an hypothesis first enunciated by turner and benjamin (n.d.). note: this paper is dedicated to the memory of daris r. swindler (august 13, 1925 – december 6, 2007). references cited bahn p. 1993. the history of human settlement on rapanui. in: fischer sr, ed. easter island studies. oxford: oxbow monograph 32:53-55. bahn p, flenley j. 1992. easter island, earth island. london: thames & hudson. bellwood p. 1987. the polynesians: prehistory of an island people. london: thames & hudson. curzon mej, curzon aj. 1971. three-rooted mandibular molars in the keewatin eskimo. can dent assoc 37:71-72. drusini ag, carrara n, orefici g, rippa bonati m. 2001. palaeodemography of the nasca valley: reconstruction of the human ecology in the southern peruvian coast. homo 52:157-172. finney, b. 1993. voyaging and isolation in rapa nui prehistory. rapa nuì journal 7:1-6. heyerdahl t. 1952. american indìans in the pacific. london: allen and unwin. hochstetter rl. 1975. incidence of trifurcated mandibular first permanent molars in the population of guam. j dent res 54:1098. houghton p. 1996. people of the great ccean: aspects of human biology of the early pacific. cambridge: cambridge university press. irwin g. 1994. the prehistoric exploration and colonization of the pacific. cambridge: cambridge university press. jones s. 1994. the peopling of the pacific. in: jones s, martin r, pilbeam d, eds. the cambridge encyclopedia of human evolution. cambridge: cambridge university press, p 394. jørgensen k. 1956. the deciduous dentition. acta odont scand (supplement 20) 14:7-191. kirch pv. 1984. the evolution of polynesian chiefdoms. cambridge: cambridge university press. loh hs. 1990. incidence and features of three-rooted permanent mandibular molars. austral dent j 35:434-437. ming-gene tu, chi-cheng tsai, ming-jia jou, lie chen, yu-fang chang, san-yue chen, hui-wen cheng. 2007. prevalence of three-rooted mandibular first molars among taiwanese individuals. j endodontics 33:1163-1166. orefici g, drusini ag. 1993. analysis of the context three-rooted m1 in easter islanders 38 of burials in the plaza of ahu tongariki. paper presented at the international conference on easter island research, university of wyoming. (abst. p. 30). pedersen po. 1949. the east greenland eskimo dentition: numerical variations and anatomy, a contribution to comparative ethnic odontography. copenhagen: meddelelser om gronland. taylor ae. 1899. variations in the human tooth-form as met with in isolated teeth. j anat physiol 33:268-272. terrell j. 1990. prehistory in pacific islands. cambridge: cambridge university press. tratman ek. 1938. three-rooted lower molars in man and their racial distribution. br dent j 64:264-274. tratman ek. 1950. comparison of teeth of people of indo-european racial stock with the mongoloid racial stock. dental record 70:31-53, 63-68. turner cg ii. 1971. three-rooted mandibular first permanent molars and the question of american indian origins. am j phys anthropol 34:229-242. turner cg ii, benjamin o. n.d.. world variation in three-rooted lower first permanent molars. paper read at the 8th international symposium on dental morphology, jerusalem, israel, 1990. van tilburg j. 1994. easter island: archaeology, ecology, and culture. washington, dc: smithsonian institution press. walker t, quackenbush le. 1985. three-rooted lower first permanent molars in hong-kong chinese. br dent j 159:298-299. a.g. drusini and d.r. swindler cunha et al. 2012.2 8 hypotrophic roots of the upper central incisors – a proposed new discrete dental trait claudia cunha 1 , ana maria silva 1* , joel irish 2 , g. richard scott 3 , tiago tomé 1 , josé marquez 4 1 research centre for anthropology and health, faculdade de ciências e tecnologia, universidade de coimbra, departamento de ciências da vida, apartado 3046 3001-401 coimbra, portugal 2 department of anthropology, university of alaska – fairbanks, po box 757720 fairbanks, ak 99775-7720, usa 3 department of anthropology, university of nevada reno, nv89557, usa 4 tera servicios de arqueología s. l. morería, 2 , 06800 , merida (badajoz), españa abstract this paper describes a newly defined nonmetric trait in the human dentition, i.e., hypotrophic roots of the upper central incisors (hruci). teeth presenting hruci are characterized by abnormally short roots whose crowns exhibit no apparent morphological alterations. the trait was observed in six samples from collective funerary sites in the iberian peninsula dated from the late neolithic to the chalcolithic period. key words: dental morphology, upper central incisors, discrete dental trait, prehistory, iberian peninsula. in the mid 20th century, a. a. dahlberg devised a set of standardized plaster casts to be used as scoring aids in recording the expression of discrete dental traits (turner et al., 1991). subsequently, publications in the 1970s through 2000s by turner, scott and others at arizona state university helped to expand, systematize, and broadly disseminate the methodology commonly used today to score traits: the arizona state university dental anthropology system (asudas) (turner et al., 1991; scott and turner, 1997). from a genetic standpoint these features are “discontinuous or quasi-continuous traits that are either present or absent or present in various degrees of expression” (larsen, 2002:137-138). in living populations, first degree relatives have frequencies of some traits six times higher than in the general population (mays, 1998). statistical tests applied to the observation of discrete dental traits have helped answer questions on genetic proximity/distance within groups (gorsky et al., 1998) and between groups (matsumura, 2007) and questions of ancestry among contemporary groups (larsen, 2002) as well as archaeological populations (irish, 2006; jackes et al., 1997; jackes and lubell, 1999). such traits have been used as a basis for inferences on the peopling of geographic regions (larsen, 2002; silva, 2002) or for the understanding of population dynamics in times of crisis, or population, cultural and/or technologi cal shifts (silva, 2002; vargiu et al., 2009). despite the considerable research and number of publications produced, the asudas is continually ‘under construction’ (scott, 2008). new contributions and changes are ongoing. new casts have been created and scoring grades for previously non-scored traits were recently published (wu and turner, 1993; burnett et al., 2010). moreover, new traits have been described and further discoveries are expected in under-studied regions and/or populations (weets, 2009). the study of dental remains from several human skeletal collections dated from the late neolithic to the chalcolithic period allowed the observation of an unusual root feature. european collections are characterized by simple morphology (scott and turner, 1988). however, individuals from the collections included in the present study exhibit various atypical characters – including ui1 presenting unusually short roots. the aim of this paper is to describe this ‘new’ discrete trait and discuss its frequency in six late prehis*correspondence to: claudia cunha, research centre for anthropology and health, faculdade de ciências e tecnologia, universidade de coimbra, departamento de ciências da vida, apartado 3046 3001-401 coimbra, portugal. email: claudia.cunha.k@gmail.com grant sponsors: fundação para ciência e a tecnologia (portuguese ministry for science, technology and higher education), grant no. sfrh-bd-70495-2010 9 toric population samples from different regions of the iberian peninsula (fig. 1). clinical approach to short roots most of the dental literature deals with the occurrence of short roots in the human dentition from a clinical perspective in modern populations. specifically, the focus is related to orthodontic treatment. hölta et al. (2004) suggest there are two general reasons for short roots: disturbances during root development, and resorption of originally well developed roots. a genetic etiology of short roots, particularly for ui1, is proposed by some (lind, 1972; jakobsson and lind, 1973; apajalahti et al., 1999; apajalahti, 2004; edgcomb , et al., 2011). however, the phenomenon is usually dealt with as an ‘anomaly’ or morphological alteration, i.e., resorption of the roots. resorption is thought to be triggered by one or more external factors, including: (1) trauma from orthodontic treatments, surgical procedures, and occlusal pressure; (2) anticancer therapy with chemotherapeutic drugs and radiation, and/or (3) industrialized toxins such as dioxins (ando et.al, 1967; hylander, 1977; brezniak and wasserstein, 2002a, b; apajalahti, 2004). population (ando et al., 1967; jakobsson and lind, 1973; thongudomporn and freer, 1998), family (apajalahti et al., 1999) and longitudinal studies (ando et.al, 1967; hölta et al., 2004) indicate that short roots in ui1 is a genetically controlled feature (brezniak and wasserstein (2002a) state that root resorption is “an unavoidable consequence of orthodontic tooth movement.”). it is more frequent in females than males at a ratio of 2.7:1 (jakobsson and lind, 1973; thongudomporn and freer, 1998); moreover, there are differences in frequencies among populations (table 1), and it may have an autosomal dominant pattern of transmission (apajalahti et al., 1999). in cases where resorption is not considered the cause, shortened roots are bilaterally expressed (jakobsson and lind, 1973; marques et al., 2010). however, as far as we know, this trait has not ethnic group/origin n prevalence reference mongoloid (japanese) 300 10% ando et.al, 1967. caucasian (swedish) 1038 2.4% jakobsson and lind, 1973. caucasian (?) (australia) 111 23.4% thongudomporn and freer, 1998. fig. 2. ui1 presenting average sized root (left) and another displaying hruci (right), both from cerro de las baterías, spain. table 1. prevalence of bilateral short roots in ui1 fig. 1. (1) cadaval cave; (2) tholos of paimogo i; (3) hypogeum of são paulo ii; (4) monument of cerro de las baterías; (5) perdigões ; (6) pit burial. 10 been employed as a normal epigenetic variant of the human dentition. materials and methods trait description: lind (1972) developed a metric method to record the phenomenon by determining the ratio between root length and crown height (r/c value) for the ui1; the method was later applied to a sample of 1,038 white children of both sexes (jakobsson and lind, 1973). the latter study reported a mean r/c value of ui1 with fully developed roots of 1.63 for males and 1.55 for females. dimorphic differences were not significant, and when the sexes were pooled the general mean r/c value was 1.6. the trait that we observed can be described as the occurrence of substantially shorter roots for ui1 that are either equal to, or shorter than the incisor crown height. for this trait, the crowns themselves are normal in appearance, and no other teeth exhibit root diminution. we propose that this trait, defined by a root:crown ratio of <1.5:1, be named hypotrophic roots of the upper central incisors (hruci) (fig. 2). further studies on samples both within and outside portugal are planned to assess the trait’s presence in other local and world regions; it also will be determined if simple presence/absence scoring, like that in asudas, is warranted for this trait. both crowns and roots of ui1 in all samples were measured using a mitutoyo digimatic caliper with an accuracy of 0.01 mm. measures were taken in labial view. root length was measured between its apex and the cement-enamel junction in the sagittal plane of the tooth (d1 in fig. 3). the crown length was measured between the cement-enamel junction, again in the mid-sagittal plane, to the most occlusal point of the incisal edge (d2 in fig. 3). teeth exhibiting roots of equal length or shorter than the crown were considered to present hruci. teeth with incisal wear of grade 3 and above [scale proposed by smith (1984), as modified by silva (1996)] were excluded from the study for two reasons: first, to avoid shortening of roots resulting from occlusal trauma caused by pressure loading; and second, because severe tooth wear would interfere in the crown-root ratio. for the same reason fragmented incisors and others in early stages of development were not considered. only teeth with an apex almost or completely closed were measured, i.e. individuals older than 8 yrs of age (smith, 1991). presence/absence dichotomy of the trait was registered to obtain the frequency of hruci in the collections. samples cadaval (cdv) is one of the burial caves in the limestone region of canteirões in the nabão river valley – a sub-tributary of the tagus river, portugal. radiocarbon dates from the human skeletal material indicate that cdv was in use between the third quarter of the 5th millennium and middle of the 4th millennium bc (tomé, 2011). cerro de las baterías is a funerary monument located in the province of badajoz, spain (fig. 1) near the town of la albuera in the guadiana river basin. although 14c dating was impossible due to taphonomic factors, the funerary assemblage accompanying the human remains presents clear parallels with local archaeological contexts dating to the 3rd millennium bc for this region of the iberian peninsula (márquez gallardo, 2008). the vaulted chamber tomb (tholos) of paimogo 1 (pmi) and the hypogeum of são paulo ii (spii) fig. 3. distances measured in order to obtain the length of roots and crowns of incisors included in the study. 11 are located in the same geomorphological region in the southwest coast of the iberian peninsula. radiocarbon dating places the use of pmi between the end of the 4th millennium and the mid 3rd millennium bc. radiocarbon dating on human remains produced dates in the 3rd millennium bc for spii (for detailed osteological data on these samples see silva, 2002; 2003). the tholos-like structures of tombs 1 and 2 of perdigões (pdg) have absolute dates pointing to the 3rd millennium bc. the site is located in reguengos de monsaraz, southeast portugal (map1) (valera and godinho, 2009). the pit burial of monte das covas 3 (mcov3) is a collective funerary monument for which there are no absolute dates. typologically this type of inhumation was in use from the late neolithic to bronze age. the site is located near beja, portugal (miguel and brazuna, 2008). in all sites except monte das covas 3, skeletons were disarticulated. although all teeth in this study come from fragmented maxillae, the skulls from monte das covas 3 were removed en bloc from the field and excavated in the laboratory; this approach allowed the identification of individuals in addition to isolated teeth from undetermined individuals. due to the nature of the trait described in this article, identification can only be made in loose teeth or via medical imaging (e.g., radiographs, ct/cat scans). cases described here were observed in loose, unassociated teeth, although in the bt07 samples compatibility of antimeres was observed (fig. 4), and in mcov3 the loose teeth could be assigned to individual skulls. the tagus and guadiana rivers, along with their tributaries, form major routes for population movement in the southern inland of the iberian peninsula; thus, a specific pattern of genetic exchange is likely. cerro de las baterías and perdigões are inland sites near the guadiana river, while cadaval is located in the tagus basin. the other sites, paimogo i and são paulo ii, are geographically more prone to coastal influences. the populations from paimogo i and são paulo ii might have had other genetic influences from groups living on and moving along the atlantic coast. results and discussion table 2 presents the total number of ui1 in the samples, the number of specimens considered for the study, and the frequencies of the trait. several other teeth excluded from the study appeared to exhibit hruci, but could not be measured and included in the total numbers due to missing portions of their anatomy. the frequency of hruci differs significantly between samples from the inland sites of cdv, bt07, pdg and mcov3 and the coastal sites of pmi and spii. coastal sites present a frequency under 16% while inland sites have frequencies above 20%. this variation may suggest a different composition of the coastal populations, different patterns of genetic exchange, and/or high endogamy in the inland sites. further study of other coeval coastal and inland populations is necessary to support any of these hypotheses. concerning possible causes that lead to the shortened roots, one common reason, suggested in archaeological, ethnographic (hylander, 1977) and clinical publications (ando et al., 1967; apajalahti, 2004; silva filho et al., 2007), is heavy occlusal pressure. this factor is not likely attributable to hruci in the present samples. load/bite fig. 4. a pair of compatible ui1 from bt07 displaying hruci (below) and a right presenting ui1 regular root length (above). 12 force resulting in resorption or premature closure of the ui1 radicular apex would have been distributed along the other anterior teeth, particularly in lower incisors to cause shortening of their roots as well. in the sample of cerro de las baterías, 158 loose lower incisors (li1 and li2) presenting closed apex and intact roots were observed to determine if a similar frequency of shortened roots matched that for ui1. only three teeth (1.89%) presented apparently short roots, and none of the li1 and li2 presented roots equal or shorter than crowns. hypercementosis, another result of heavy occusal trauma, is absent in ui1 from the samples. in cases of severe root resorption from repetitive or continuous trauma (e.g., occlusal trauma, tooth movement, etc.), shortening appears to be the natural response of the organism to repair the affected area. in such cases, dentin layers beneath the cementum are affected. the repair process generally begins two weeks after forces that caused the trauma end, and involve active cementum deposition (brezniak and wasserstein, 2002a). in archaeological material the most obvious result of this repair process is an irregular layer of cementum altering the physiologic limits of the root – hypercementosis (fig. 5). although there are cases of hypercementosis in the present study, none affected ui1. other factors listed for shortening of roots in contemporary populations (i.e., clinical treatments, drug use, contamination by chemical agents) do not fit the profile for the prehistoric samples. therefore, a genetic etiology for the phenomenon seems to be the most likely explanation. clinical literature suggests that at least part of the cases studied in contemporary populations appear to have a genetic pattern of inheritance and family prevalence (lind, 1972; jakobsson and lind, 1973; apajalahti et al., 1999; edgcomb et al., 2011). observation of the sample from mcov3 and cases of compatible antimeres in bt07 suggest that hruci is often bilateral in expression. at present, sample sizes are too small to assess site total of ui1 in the collection measured ui1 ui1 presenting hruci left right left right left right cdv 10 11 3 6 1 (33.3%) 3 (50.0%) pdg 50 31 25 11 5 (20.0%) 3 (27.3%) bt07 80 87 37 28 15 (40.5%) 10 (35.8%) pmi 119 103 108 90 17 (15.7%) 11 (12.2%) spii 89 76 66 59 10 (15.2%) 8 (13.6%) mcov3 10 13 5 7 2 (40.0%) 3 (42.9%) table 2. frequencies of hruci in the sites of cadaval (cdv), perdigões (pdg), cerro de las baterías (bt07), paimogo i (pmi), são paulo ii (spii) and monte das covas 3 (mcov3) per side of jaw. fig. 5. smooth root surface on a hruci ui1 (right) and irregular surface of a blunt root in a ui2 (left) presenting evidence of hypercementosis. 13 trait independence. inter-trait associations also will be addressed in future research. further research on this trait is necessary to verify its genetic nature. other collections need to be assessed to confirm the differences of frequencies between inland and coastal areas in the late prehistory of the iberian peninsula. comparative studies with other archaeological samples are needed to verify if this trait is of local expression or is present in other regions. these studies will be important tools in the assessment of biodistances for populations recovered from prehistoric contexts in the iberian peninsula. acknowledgments this study was made possible thanks to phd grant sfrh-bd-70495-2010 from fundação para ciência e a tecnologia (portuguese ministry for science, technology and higher education). our gratitude also goes to the center of prehistory at the instituto politécnico de tomar and to the department of life sciences at the university of coimbra in whose labs the study took place. academic and institutional support for the research developed also has been granted by the research center for anthropology and health (cias) at the university of coimbra. this work would not be possible without the consent of consejería de cultura y turismo de la comunidad autónoma de extremadura. we acknowledge the contribution of dr. isabel luna from the municipal museum of torres vedras and dr. luis barros from the municipal museum of almada for authorizing the study of the osteological collections of paimogo i and são paulo ii, also discussed in this paper. we acknowledge the support given to our lab work by perdigões scientific and heritage management project and era-arqueologia, s.a in allowing the study of the collections of peridigões and monte das covas. literature cited ando s, kiyokawa k, nakashima t, shinbo, k, sanka y, oshima s, aizawa k. 1967. studies on the consecutive survey of succedaneous and permanent dentition in the japa nese chil dren. part 4: behaviour of shortr o o t e d teeth in the upper bilateral central incisors. journal of nikon university school of den tistry 9:67-80. apajalahti s. 2004. short root anomaly (sra). prevalence and phenotypic features in families with emphasis on matrix metalloproteinases in gengival crevicular fluid of sra and orthodontic patients. phd dissertation, university of helsinki, finland. apajalahti s, arte s, pirinen s. 1999. short root anomaly in families and its association with other dental anomalies. eur j oral sci, 107:97 101. brezniak n, wasserstein a. 2002a. orthodontically induced inflammatory root resorption. part i: the basic science aspects. angle orthodontist, 72:175-179. brezniak n, wasserstein a. 2002b. orthodontically induced inflammatory root resorption. part ii: the clinical aspects. angle orthodontist, 72:175-179. burnett s, hawkey d, turner cg ii. 2010. brief communication: population variation in human maxillary accessory ridges. am j phys anthropol 141:319-324. edgcomb k, begole e, evans c, johnson b, luan x. 2011. prevalence of short dental roots in four ethnic groups in orthodontic population. dental anthropology, vol. 24, 1:11-15. fuller j, denehy g, schulein t. 2001. concise dental anatomy and morphology. fourth edition. university of iowa college of dentistry. grorsky m, bukai a, shohat, m. 1998. genetic influence on the prevalence of torus palatino. am j medical genet 75:138-140. hölta p, nyström m, evälahti m, alaluusua s. 2004. root-crown ratios of permanent teeth in a healthy finnish population assessed from panoramic radiographs. eur j orthodontics, 26:491-497. hylander wl. 1977. the adaptive significance of eskimo craniofacial morphology. in dahlberg aa, graber tm, editors. orthofacial growth and development. the hague: mouton. p 129169. irish j. 2006. who were the ancient egyptians? dental affinities among neolithic through post dynastic peoples. am j phys anthropol 129:529 543. jackes m, lubell d. 1999. human skeletal biology and the mesolithic-neolithic transition in portugal. l’europe des derniers chasseurs, 5º colloque international uispp 59-64. jackes m, lubell d, meiklejohn c. 1997. healthy 14 but mortal: human biology and the first farmers of western europe. antiquity 71:639-658. jakobsson r, lind v. 1973. variation in root length of the permanent maxillary central incisor. scand j dent res, 81:335-338. larsen c. 2002. bioarchaeology: the lives and life styles of past people. j archaeol res 10:119-166. lind, v. 1972. short root anomaly. scand j dent res 80:85–93. marques l, generoso r, armond m, pazzini c. 2010. short-root anomaly in an orthodontic patient. am j orthodontics and dentofacial orthopedics 138:346-348. márquez gallardo jm. 2008. cerro de las baterías, la albuera (badajoz) – memoria de intervención arqueológica. excavation report. author’s edition. matsumura h. 2007. non-metric dental trait varia tion among local sites and regional groups of the neolithic jomon period, japan. anthropological science 115:25-33. the anthropological society of japan. mays s. 1998. archaeology of human bones. london: routledge. miguel l, brazuna, s. 2008. relatório dos trabalhos arqueológicos minimização de impactes sobre o património cultural decorrentes da execução da empreitada de beneficiação da rede viária e rede de drenagem do aproveitamento hidroagrícola de alvito -pisão. monte das covas 3. era arqueologia sa. scott gr. 2008. dental morphology. in: katzenberg a, saunders s, editors. biological anthropology of the human skeleton. new york: wiley-liss, p. 265-298. scott gr, turner, cg ii. 1988. dental anthropology. ann rev anthropol 17:99-126. scott gr, turner, cg ii. 1997. the anthropology of modern human teeth – dental morphology and its variation in recent human populations. cambridge: cambridge university press. silva, am. 1996. o hipogeu de monte canelas i (iv-iii milénios a. c.): estudo paleobiológico da população humana exumada. trabalho de síntese. provas de aptidão pedagógica e capacidade científica. coimbra, departamento de antropologia, faculdade de ciências e tecnologia da universidade de coimbra. silva, am. 2002. antropologia funerária e paleobiologia das populações portuguesas (litorais) do neolítico final/calcolítico. phd dissertation, universidade de coimbra. silva, am. 2003. portuguese populations of late neolithic and chalcolithic periods exhumed from collective burials: an overview. anthropologie, xli/1-2: 55-64. silva filho o, mateus s, da silva v, oliveira g. 2007. nanismo radicular – short root anomaly. revista ortodontiaspo vol. 40, 4:305-310. smith b. 1984. patterns of molar wear in hunter gatherers and agriculturalists. am j phys anthropol 63:39-56. smith b. 1991. standards of human tooth formation and dental age assessment. in: kelley m, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p. 143-168. thongudomporn u, freer t. 1998. prevalence of dental anomalies in orthodontic patients. aus dent j 43(6):395-398. tomé, t. 2011. até que a morte nos reúna: paleobiologia e antropologia funerária da transição para o agro-pastoralismo na bacia do tejo e sudoeste peninsular. phd dissertation. universidade de trás-os-montes e alto douro. turner cg ii, nichol c, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley m, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p. 13-31. valera a, godinho r. 2009. a gestão da morte nos perdigões (reguengos de monsaraz): novos dados, novos problemas. est arq de oeiras vol 17:371-387. vargiu r, cucina a, coppa a. 2009. italian populations during the copper age: assessment of biological affinities through morphological dental traits. hum biol 81:479 493. weets j. 2009. a promising mandibular trait in ancient populations of ireland. dental anthropology 22:65-72. wu l, turner cg ii. 1993. brief communication: variation in the frequency and form of the lower permanent molar middle trigonid crest. am j phys anthropol 91:245-248. artaria 2010.2 74 the dental morphology of southeast asia is poorly known. studies in dental anthropology have never been conducted on indonesians even though the area has a rich variety of peoples and cultures. data on the variety of populations in this area may be useful regarding human evolution (hillson, 2002), migration patterns (scott and turner, 2000), and for evaluating forensic cases (brown, 1992). previous studies have assessed menarcheal age (artaria and henneberg, 2000), mesiodistal diameters of the primary dentition (kuswandari and nishino, 2004), and adolescents’ growth and development (artaria, 2009), but little has been found on the characteristics of the dentition in javanese people, so it is useful to initiate studies of this kind. previous study on the javanese dentition (artaria, 2007) found that shovel shape, winging, tuberculum dentale, interruption groove, canine distal accessory ridge, premolar accessory ridges, premolar multiple lingual cusps, cusp 5, cusp 6, y5 pattern, cusp 7, protostylid, deflecting wrinkle, anterior fovea, and carabelli’s cusp occurred in the sample. however, that preliminary sample size was small, and no scoring was done for each variable. the literature suggest that dental variation is heritable, the traits appear to be controlled by multiple genes, and they are little influenced by environmental factors (rodríguez-flórez et al., 2006), so phenotypic differences among samples can be interpreted as differences in genotypic composition (varela and cocilovo, 2000). phenotypic similarity is suggested to approximate genetic similarity. research on the primary dentition of javanese children (kuswandari and nishino, 2004) found that the mesiodistal tooth diameters fell between those of australian aboriginals and hong kong chinese. this makes sense because jacob (1967) and others note that the islands of indonesia historically were occupied by ancient homo sapiens similar to those of the australians. the teeth of the javanese may reflect the admixture of two ancestral lines, namely australomelanesid and mongoloid. the goal of the present research was to describe the frequencies of some common dental traits as they were represented in a contemporary sample of javanese. material and methods the sample was 91 individuals from the surabaya, east java (indonesia). the dental traits examined were shovel shape, double shovel, winging, tuberculum dentale, interruption groove, canine distal accessory ridges, carabelli’s cusp, odontomes, premolar accessory ridge, parastyle, multiple lingual cusps, dryopithecus pattern, cusp 5, cusp 6, cusp 7, deflecting wrinkle, anterior fovea, protostylid, and uncommon shape/place of lateral incisors. dental traits were scored using the descriptions in scott and turner (2000), and the dental plaques provided by asu. percentages were counted using simple descriptive statistic analysis. results and discussion scott and turner (2000) have divided the world’s populations into five groups based on their dentitions. the dental traits of sahul-pacific group—the same area occupied by the australomelanesid according to jacob (1967)—exhibit dental characteristics such as frequent expression of cusp 5, carabelli’s cusp, and cusp 6. in contrast, there are rare expressions of winging, shoveling, double shoveling, interruption grooves, and cusp 7. further, they have intermediate position for several the dental traits of indonesian javanese myrtati dyah artaria department of anthropology, fisip, universitas airlangga, jl. airlangga 4-6, surabaya, east java, indonesia 60286 dental traits of indonesian javanese abstract this study describes the dental crown morphology of 91 javanese of known sex and age, in surabaya, east java. the purpose was to explore the dental morphology in the area of east java, especially in surabaya. i scored a battery of three dozen dental traits on the permanent dentition (sexes pooled). comparisons of the trait frequencies show that this javanese sample does not exhibit a classic combination either of the sinodont or sundadont dental patterns. instead, it represents some features of each, and this probably is due to the millennia of human migrations through this region. dental anthropology 2010(23):74-78. correspondence: myrtati dyah artaria, department of anthropology, fisip, universitas airlangga, jl. airlangga 4-6, surabaya 60286, indonesia. grant sponsorship: fisip unair grant e-mail: myrtati@gmail.com 75javanese dental morphology traits such as odontomes, 4 cusped lm1 and lm2, lm2 y pattern, and deflecting wrinkle. the sino-americas group, according to scott and turner (2000) has characteristics of dentition such as high frequency of winging, double shoveling, interruption grooves, odontomes, cusp 6, and deflecting wrinkle. the sunda pacific groups have no high frequency dental traits that set them apart; however, they have high frequencies of carabelli’s cusp and cusp 6, and low frequencies of cusp 7 and 4-cusped lm1. shovel shape had been widely studied by several authors (e.g., campusano et al., 1972; dahlberg, 1951; devoto et al., 1968; bollini et al., 2006; nelson, 1938; rothhammer et al., 1968). most of these studies concluded that high frequency of strong shovel shaped incisors was found in mongoloid populations, especially those descendants of mongoloid people from the asian continent. a study by bollini et al. (2009) reported a high frequency of shovel shape (80%) but absence of carabelli’s complex in the pre-conquest sample “calchaquí” from argentina. in the present sample, shovel shape was common, although the expressions were mostly grades 2 and 3 (table 1) using the asu shovel shape dental plaque. this is expected given the asian ancestry of the group, especially the sundadont. the most frequent degree of expression for upper first incisor and lateral incisors was 2. it was also noteworthy that the frequency of the sample that did not have shoveled-shape upper incisors was comparatively high—8% to 9% (table 1). these frequencies for shoveling suggest similarities to the sunda pacific group. some subjects have slight double shovel (table 1). the frequency of double shovel in recent southeast asia predicted by scott and turner (2000) is 5% to 18%. however, this higher frequency in these javanese may reflect admixture of the surabayan people in the coastal area of northeast java with the sinodont-people from asia who migrated to the indonesian areas during the first to second centuries. double shovel was found in the upper central incisors in 73% of the sample, but only in a weak expression, scores 1 to 3, and 47% of the sample had double shovel of their lateral incisors. double shoveling frequency is similar to that of the sunda pacific group. high frequencies of winging are usually found in sinodont dentitions, especially groups in northeast siberia and north america. the people of java are labeled sundadont, and some data suggest that sundadont groups may also have high frequencies of winging. the sunda pacific group is suggested to exhibit winging on the order of 15% to 28% (scott and turner, 2000). incisor winging occurred in 15% of the present sample (table 2), so it is comparable to the sunda pacific group as described by scott and turner. expression of tuberculum dentale was weak to moderate, and most individuals—47%—lacked tuberculum dentale on their central incisors (table 2). only 3% exhibited a more pronounced—score 3—grade of tuberculum dentale. this is neither characteristic of sino americas nor sahul pacific, but more like that of sunda pacific groups. according to scott and turner (2000), the sundapacific people—including southeast asians—have frequencies of 25% to 35% with interruption grooves on the second incisors. however, interruption grooves on the upper second incisors occurred in only 12% of the current sample (table 2). this low frequency of interruption grooves is more similar to sahul pacific groups. upper lateral incisors can undergo rotation, crowding, or reduced size (table 2), and the uncommon shape or placement of lateral incisors occurred in a small number of the sample (2%). instead of having uncommon shape/ size of lateral incisors—as is more common in caucasian samples, mongoloids seem to have more cases of winging of central incisors (c. g. turner, pers. comm.). no bushmen canine was found in the sample. canine distal accessory ridge occurred in 69% of the sample (table 3). the occurrence of distal accessory ridges on table 1. percentages of shovel and double shovel shape† shovel shovel shovel lower double shovel grade ui1 ui2 i and c ui1 ui2 0 8.8 7.7 62.3 26.2 53.3 1 8.8 24.2 27.9 57.4 38.3 2 40.7 30.8 8.2 14.8 7.4 3 24.2 17.6 1.6 1.6 0.0 4 9.9 13.2 0.0 0.0 0.0 5 7.7 3.3 0.0 0.0 0.0 6 0.0 0.0 0.0 0.0 0.0 7 0.0 2.2 0.0 0.0 0.0 missing 0.0 1.0 0.0 0.0 1.0 total 100.0 100.0 100.0 100.0 100.0 †ui1: upper central incisor, ui2: upper lateral incisor, i: incisor, c: canine table 2. percentage of tuberculum dentale (td), interruption groove (ig), maxillary incisor winging, and uncommon shape/ place of lateral incisors (li) grade td ig winging li shape 0 47.3 86.7 84.6 0.0 1 18.7 12.3 7.7 0.0 2 24.2 0.0 5.5 0.0 3 3.3 0.0 2.2 0.0 absent 0.0 0.0 0.0 98.3 present 0.0 0.0 0.0 1.7 missing 0.0 1.0 0.0 0.0 total 100.0 100.0 100.0 100.0 76 the lower canine was less common (12% of the sample). research is needed to find out whether there is sexual dimorphism in this particular trait. there was an indication of sexual dimorphism— males having larger cusps—for carabelli’s trait (khraisat et al., 2007). according to mavrodisz et al. (2007), there is a genetic influence on the carabelli’s trait. there also is a positive association between carabelli’s cusp and tooth crown size (garn et al., 1966; harris, 2007). carabelli’s trait complex was expressed in more than 70% of the cases (table 4), with the degree of expression ranging from 0 to 7. the high percentage of carabelli’s cusp is the characteristic of both sunda pacific and sahul pacific. however, according to scott and turner (2000), the percentage may reach 25%, but not as high as 70%. this outstanding occurrence of carabelli’s cusp may be related to some other factors, such as the size of the tooth crown (harris, 2007) or sampling fluctuation. further research in this matter may be conducted in the near future. the parastyle occurred on 2% (m3) to 6% (m2) of the molars, while no parastyle nor cusp 5 was found on m1 (table 4). the absence of cusp 5 certainly is not a characteristic of sahul pacific groups; it is more characteristic of sino americans according to scott and turner (2000). the groove pattern was mostly of the x pattern (table 5). the dryopithecus pattern (y pattern lm2) was found in 7% of the sample. the frequency of the y pattern of australians (sahul pacific group) is approximately 21%. the percentage of y pattern on lm2 in china mongolia and north and south america (sino americas group) is around 8-9%, and in the sunda pacific is around 19% (scott and turner, 2000), so the percentage of the y pattern in this sample was closer to the sino american condition. cusp 6 was found in 6% of the sample, and no cusp 7 was found (table 5). the closest percentage of cusp 6 occurrence was the new guinea people (sahul pacific) that has around 18% of people with the dental trait. the south siberian (sino american group) has 20%, and the southeast asians (sunda pacific group) 32% (scott and turner, 2000). cusp 7 is a common characteristic in subsaharan peoples, while low frequencies (0-10%) generally occur in the sino americas, sahul pacific, and sunda pacific groups (scott and turner, 2000), so this accessory cusp is, not surprisingly, absent in this javanese sample. most of the sample (above 90%) had no deflecting wrinkle or anterior fovea (table 5). deflecting wrinkle was found in 3%, and anterior fovea was in 7% of the sample. the closest percentage of deflecting wrinkle was found in the new guinean people—around 5% of the people. the recent southeast asian (sunda pacific group) has 15%, and other sino americas around 30% and above (scott and turner, 2000). the protostylid occurred predominately on m1, with a frequency above 50% (table 5). similar to the carabelli cusp, the protostylid also is positively associated with crown size (scott and turner, 2000). further they stated that the protostylid was frequently expressed on lm1— which was true for this sample, but when it appeared on lm2 the size often was bigger. accessory ridge was found in 10% to 29% of the upper premolars in the sample (table 6), while the percentage of sample having accessory ridges on the lower premolars was even less, namely 1-2% (table 7) as expected. there were no odontomes (table 6 and 7), although scott and turner (2000) estimated that 1 to 4% of recent southeast table 3. percentages of distal accessory ridge (dar) and the bushmen canine† bushmen score dar uc dar lc uc 0 31.1 88.5 100.0 1 49.2 11.5 0.0 2 19.7 0.0 0.0 missing 0.0 0.0 0.0 total 100.0 100.0 100.0 †u = upper, l = lower, c = canine table 4. trait percentages on the upper molars† score um1c um2c um1c5 um1pa um2pa um3pa 0 20.9 71.4 100.0 100.0 93.3 17.6 1 40.7 15.4 0.0 0.0 5.6 2.2 2 20.9 12.1 0.0 0.0 0.0 0.0 3 9.9 0.0 0.0 0.0 0.0 0.0 4 2.2 0.0 0.0 0.0 0.0 0.0 5 2.2 0.0 0.0 0.0 0.0 0.0 6 0.0 0.0 0.0 0.0 0.0 0.0 7 3.3 0.0 0.0 0.0 0.0 0.0 missing 0.0 1.1 0.0 0.0 1.1 80.2 total 100.0 100.0 100.0 100.0 100.0 100.0 †u = upper, m = molar, c = carabelli’s cusp, c5 = cusp 5, pa = parastyle m.d. artaria 77 table 5. percentage of traits in lower molars† score lm2gp lm1c6 lm1c7 lm1dw lm1af lm1po lm2po lm3po 0 24.6 94.3 100.0 96.2 92.6 47.3 65.6 13.2 1 6.6 5.7 0.0 3.8 7.4 52.7 34.4 4.4 2 65.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3 3.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 missing 0.0 0.0 0.0 0.0 0.0 0.0 0.0 82.4 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 †l=lower, m=molar, gp=groove pattern, score 0: unclear groove/missing tooth, score 1: dryopithecus pattern, score 2: x pattern, score 3: + pattern; c6=cusp 6, c7=cusp 7, dw=deflecting wrinkle, af=anterior fovea, po = protostylid asian people have odontomes. multiple lingual cusps were found mostly on the lower second premolar. the cusps were also more complicated on the second lower premolars (table 7). conclusion based on the finding in this javanese sample, the trait frequencies were more like sunda pacific. the sundadont people who have higher frequency of derived traits are thought to have evolved on sundaland during upper pleistocene. they exhibit a “more conservative pattern, typified by trait retention rather than elaboration” (scott and turner, 2000). the traits with frequencies similar to the sunda pacific group were shoveling, double shovel, winging, and tuberculum dentale. however, other percentages mirror those of the sino americas, and still others those of sahul pacific. trait frequencies similar to sino americas were cusp 5 and the y pattern. percentages similar to sahul pacific were interruption grooves, cusp 6, and deflecting wrinkle. consequently, this sample of javanese is not monolithic as regards either the sinodont or sundadont dental patterns. instead, they exhibit some features of each, probably because of the millennia of human migrations through this region. literature cited artaria md, henneberg m. 2000. why did they lie: socioeconomic bias in reporting menarcheal age. ann hum biol 27:561-569. artaria md. 2007. short communication: dental trait variation and age determination based on dental wear: a preliminary study of javanese. dental anthropology 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american indian. new york: viking fund inc., 1951, p 138-176. devoto fch, arias nh, ringuelet s and palma nh. 1968. shovel-shaped incisors in a northwertern argentine population. j dent res 47:820-823. garn sm, lewis ab, kerewsky rs, dahlberg aa. 1966. genetic independence of carabelli’s trait from tooth size or crown morphology. arch oral biol 11:745-747. harris ef. 2007. carabelli’s trait and tooth size of human maxillary first molars. am j phys anthropol 132:238246. hillson s. 2002. dental anthropology. cambridge: cambridge university press. jacob t. 1967. some problems pertaining to the racial history of the indonesia region. unpublished thesis. utrecht. table 6. the percentage of traits in upper premolars† score up1ar up2ar up1od up2od 0 90.0 71.4 100.0 100.0 1 10.0 28.6 0.0 0.0 missing 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 †u = upper, p = premolar, ar = accessory ridge, od = odontome javanese dental morphology 78 khraisat a, taha st, jung re, hattar s, smadi l, al-omari ik, jarbawi m. 2007. prevalence, association, and sexual dimorphism of carabelli’s molar and shovel incisor traits amongst jordanian population. odontostomatol trop 30:17-21. kuswandari s, and nishino m. 2004. the mesiodistal crown diameters of primary dentition in indonesian javanese children. arch oral biol 9:217-222. maples wr, browning m. 1994. death in 10,000 fragments. in: maples wr and browning m, editors. dead men do tell tales. new york: doubleday. mavrodisz k, rózsa n , budai m , soós a., pap i and tarján i. 2007. prevalence of accessory tooth cusps in a contemporary and ancestral hungarian population. eur j orthod 29:166–169. nelson ct. 1938. the teeth of the indians pecos pueblo. am j phys anthropol 23:261-93. rodríguez-flórez cd, fonseca gm, villalba mt. 2006. brief communication: occurrence of an eighth cusp on primary second mandibular molars of a contemporary argentinean child. dental anthropology 19:73-75. rothhammer f, lasserre r, blanco r, covarrubias e, dixon m. 1968. microevolution in human chilean populations. iv. shovel shape, mesial-palatal version and other dental traits in pewenche indians. z morphol anthropol 60:162-169. scott gr, turner cg ii. 2000. the anthropology of modern human teeth. cambridge: cambridge university press. varela hh, cocilovo ja. 2000. structure of the prehistoric population of san pedro de atacama. curr anthropol 41:125-131. table 7. trait percentage on the lower premolars† score lp1ar lp2ar lp1od lp2od lp1mlc lp2mlc 0 98.4 98.3 100.0 100.0 94.8 36.2 1 1.6 1.7 0.0 0.0 5.2 37.9 2 0.0 0.0 0.0 0.0 0.0 22.4 3 0.0 0.0 0.0 0.0 0.0 3.4 missing 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 †l = lower, p = premolar, ar = accessory ridge, od = odontome, mlc = multiple lingual cusps m.d. artaria higgins et al. 2009.1 1 a central focus of dental anthropological study over the last century or so has involved metric and nonmetric analysis of the features of human teeth (scott and turner, 1977). the crowns of upper molar teeth have four main cusps and these are termed the paracone (mesiobuccal), protocone (mesiolingual), metacone (distobuccal), and hypocone (distolingual). hypocone expression, like other non-metric dental crown traits, is generally scored by comparison with standardised plaques (turner et al., 2001). these plaques aid visual assessment of presence and degree of expression. in the context of phylogeny, dental characters are associated with functional demands and dietary adaptations but also reflect the developmental processes controlling morphogenesis. the field theory that was proposed by butler (1939) and adapted by dahlberg (1945) in an attempt to account for the common features of teeth within a class, postulated that the most mesial tooth in each morphological class is usually the most stable phenotypically. osborn (1978), in his clone theory, proposed that a single clone of preprogrammed cells led to the development of all teeth within a particular class. both of these theories provide strong genetic influence on hypocone expression of permanent maxillary molars in south australian twins denice higgins*, toby e. hughes, helen james, grant c. townsend craniofacial biology research group, school of dentistry, the university of adelaide, south australia 5005 *correspondence to: dr denice higgins, forensic odontology unit, school of dentistry, faculty of health sciences, university of adelaide, 5005, south australia. e-mail: denice.higgins@adelaide.edu.au abstract an understanding of the role of genetic influences on dental traits is important in the areas of forensic odontology, human evolution and population variation. the aims of this study were: to calculate the frequency of occurrence and degree of expression of hypocones on permanent maxillary first and second molars in a sample of south australian twins; to compare trait expression between males and females; to compare concordance rates for trait expression between monozygotic (mz) and dizygotic (dz) twins; and to fit genetic models to the data derived from twins and determine heritability estimates. using stone dental casts, hypocone expression was scored on maxillary permanent first and second molars of 45 mz twin pairs and 43 dz pairs. degrees of expression were scored from absence, through minor wrinkles or ridges, to very large cusps (score 0 – 5) using the standardized method of turner et al. (1991). hypocones were found to be more common and larger on first molars than second molars and there was a tendency for them to be larger in males although this was not statistically significant. no significant differences in occurrence or expression were noted between antimeres, with fewer differences observed between first than second molars. the percentage concordance for expression in mz twin pairs was higher than in dz twin pairs indicating a genetic influence determining the variation observed in hypocone expression. the most parsimonious model to explain observed variation was an ae model, incorporating additive genetic and unique environmental effects. narrow-sense heritability estimates for both the first and second molars were high indicating that a large portion of the phenotypic variation could be explained by additive genetic effects. the greater range of phenotypic expression shown by the second molars compared with the first molars may reflect a common genetic liability that is modulated by differences in tooth size, location and/or developmental timing between these teeth. dental anthropology 2009;22(1):1-7. insights into the mechanisms that may be involved in patterning within the human dentition. recent progress in studying these mechanisms at a molecular level indicates the involvement of homeobox-containing genes (mitsiadis and smith, 2006). recently, mitsiadis and smith (2006) and townsend et al. (2008) have proposed a new genetic developmental model for teeth that incorporates the field, clone and homeobox code theories. current evidence on development shows that tooth morphogenesis is punctuated by transient signaling centers in the epithelium, the primary and secondary enamel knots, corresponding to the initiation of tooth crowns and individual cusps (jernvall, 2000). differential growth and subsequent folding of the dental epithelium is directed by the enamel knots, which are composed of non-dividing cells. cell proliferation around the 2 enamel knots is believed to be influenced by members of the fibroblast growth factor family. genes involved in cusp development appear to be the same among all the individual cusps, with no particular gene for a single cusp, which means that at the level of molecular signaling, all the cusps are alike. a patterned cascade mode of cusp spacing may promote the evolution of new cusps and individual teeth may differ only in the timing of cusp initiation (jernvall, 2000). as the secondary enamel knot program is repeated for every cusp, any small difference in cusp spacing will have a cumulative effect on later-developing cusps (jernvall, 2000). reflecting this concept, studies have shown that hypocones show the greatest variation in size of all upper maxillary molar cusps in hominoid primates and in humans (jernvall and jung, 2000; kondo et al., 2005). insight into the relative contributions of genetic and environmental factors to human tooth development can be gained from twin studies involving the comparison of monozygotic (mz) and dizygotic (dz) twin pairs. differences between mz twin pairs can be expected to be of similar magnitude to the minor left right differences that may be observed in singletons, whereas the differences between dz pairs are similar to those seen in siblings (kabban et al., 2001). the purpose of this study was to investigate size variability of the hypocone of permanent maxillary first and second molars in a sample of south australian twins. the specific hypotheses that were tested were: • that hypocones occur more frequently and are larger in first molars compared with second molars • that hypocones occur more frequently and are larger in males than females • that hypocone expression is symmetrical between antimeric teeth • that monozygotic twin pairs exhibit a higher degree of concordance for hypocone trait expression than dizygotic twin pairs, indicating a genetic contribution to observed variation. materials and methods from a collection of dental casts of over 600 twin pairs, 45 mz and 43 dz pairs were selected. the twins were all of european ancestry and were aged between 10 and 46 years. only individuals with permanent maxillary first and second molars present on both left and right sides were included. subjects selected did not have any extensive restorations and their casts were not damaged. the study was approved by the committee on the ethics of human experimentation, university of adelaide (approval no. h/07/84) as part of an ongoing study of the teeth of australian twins. hypocones were scored on right and left maxillary first and second molars using turner’s asu classification system (arizona state university system, plaque 8) (scott and turner, 1997) with 6 grades of expression. score 0 represented absence of a cusp, score 1 indicated a ridge or wrinkle present at the cusp site, score 2 was a faint cuspule, score 3 was a small cusp, score 4 was a large cusp and score 5 was a very large cusp. the casts were examined under a magnifying light and the degree of expression was determined by reference to a plaster replica of the scoring plaque. assessments were made for all subjects on two separate occasions so that concordance rates between determinations could be calculated. a second observer scored 30 randomly selected casts for determination of inter-examiner reliability. statistical analysis was carried out using spss for windows©. frequencies were calculated for right and left side teeth, and for males and females. associations between sides, first and second molars, and sexes were tested using chi-square tests. statistical significance was set at an alpha of 0.05. as a preliminary assessment of possible genetic influence on phenotypic expression, concordances rates were calculated for mz and dz pairs for all hypocone expressions. structural equation modelling was then undertaken using the software package mx (neale et al., 2006). mx is a structural equation modelling package, flexible enough to fit a variety of mathematical applications. at its heart is a matrix algebra processor. there are many built-in fit functions to enable structural equation modelling (sem) and other experiments in matrix algebra and statistical modelling, including facilities for maximum likelihood estimation of parameters from missing data structures, under normal theory. complex ‘non-standard’ models are easy to specify. for further general applicability, it allows users to define their own fit functions, and optimization may be performed subject to linear and nonlinear equality or boundary constraints. mx can be used to apply structural equation models to variance-covariance matrices derived from monozygotic (mz) and dizygotic (dz) twin data. this method is particularly well-suited for continuously distributed data. however, sem methodology can be extended to dichotomous and ordinal twin data by substituting the tetrachoric or polychoric correlation matrix (pearson, 1901) for the variance-covariance matrix (neale and cardon, 1992). use of sem methodology for ordinal data is dependent on the assumption of an underlying continuous liability distribution that is bivariate normal. that is, it is assumed that categories are formed by imposing thresholds on a continuous liability distribution (falconer, 1965; reich et al., 1972). four sources of variation: a, additive genetic variance; d, non-additive genetic variance; c, common [shared] environmental variance; and e, unique [nonshared] environmental variance were modelled for twin pairs. a represents the additive effects of the alleles at a locus, whilst d refers to intralocus gene interactions. d. higgins et al. 3 c affects twin similarity regardless of zygosity, whereas e only represents unique effects contributing to withinpair differences. implicit in the model-fitting were the normal assumptions of the twin method: that mating was random; that trait-related, shared environmental influences on mz and dz twins were equal; and that there was no gxe interaction or gene-environment covariation (jinks and fulker, 1970). since fitting models with four parameters to data from a classical twin study (mz and dz twins reared together) results in an underidentified model (grayson, 1989; hewitt, 1989; dempsey et al., 1999), subsets of three or fewer parameters were chosen. rectangular files of raw ordinal data were prepared as described by neale et al. (2006) and utilized directly for univariate analyses of ordinal data, maximising the likelihood under a bivariate normal distribution model. for right and left first molars, scores of 3 or less were combined into a single category (i.e., < 3) as only one tooth was scored less than a 3. starting values for model thresholds were estimated from raw frequencies. when analysing raw data, there is no direct measure of goodness of model fit. instead, nested sub-models can be compared by examining the log of the likelihood function (logl). nested model differences in -2logl are distributed asymptotically as a χ2, with degrees of freedom equal to the differences in free parameters between nested sub-models (e.g., ace vs ae = 1 df). initially, a cholesky decomposition of the data was undertaken to produce a saturated model fit against which to test goodness-of-fit of nested sub-models. where models were not nested (i.e., ace vs ade), the relative magnitude of the log of the likelihood was used to indicate the parsimony of each model. the general approach was that of accepting a more complex model only when a simpler one had failed. path coefficients (a, c, e) were estimated. heterogeneity of causes of variation between sexes was also evaluated. narrow-sense heritability estimates (h2) were calculated from the ratio of genetic variation (a) to total phenotypic variation (a+c+d+e) in the best-fitting model. values of heritability estimates near 1 indicate that most of the phenotypic variation can be explained by additive genetic effects whereas values near zero indicate that environmental effects account for most of the variation in the phenotype. results concordance between the first and second sets of scores was 98% and there was no indication of systematic methodological errors. inter-examiner concordance was 72% and the discrepancies found were generally of the order of plus or minus one category. hypocones were present on all permanent first molars and on a high proportion of second molars as demonstrated in table 1. pronounced expressions of hypocones were noted on first molars, with only one individual having a score of less than 3, and a high proportion of score 4 or 5. the second molars demonstrated more variation in hypocone expression. subsequent genetic analysis treated hypocone expression on first molars as an ordinal trait with fewer categories than the second molars, yielding significantly lower power than the model for second molars, and consequently broader confidence intervals for parameter estimates. females had more pronounced expressions of score 4 and 5 on first molars, whereas the second molars showed more variability. only 2% of females showed scores of table 1. expression of hypocone trait in males and females (one member of each twin pair)1 males females first molar second molar first molar second molar right left right left right left right left score n % n % n % n % n % n % n % n % 0 0 0.0 0 0.0 4 11.0 3 8.0 0 0.0 0 0.0 5 9.6 9 17.3 1 0 0.0 0 0.0 8 22.0 5 14.0 1 1.9 0 0.0 15 28.8 8 15.4 2 0 0.0 0 0.0 4 11.0 4 11.0 0 0.0 0 0.0 6 11.5 7 13.5 3 0 0.0 0 0.0 9 25.0 12 33.0 3 5.8 3 5.8 15 28.5 17 32.7 4 19 53.0 19 53.0 9 25.0 10 28.0 28 53.8 29 55.8 10 19.2 10 19.2 5 17 47.0 17 47.0 2 6.0 2 6.0 20 38.5 20 38.5 1 1.9 1 1.9 1 n = 88 genetic influence on hypocone expression 4 5 on both upper right and left second molars. males showed a higher percentage of score 5 than females, with 47% of males showing score 5 compared to 38% of females. females showed a higher percentage of score 4 and below. there was a tendency for male hypocones to be larger but this was not statistically significant. in first molars, 98% concordance in expression between antimeric teeth was noted. the only example of marked asymmetry was one individual with score 1 on the left first molar and score 4 on the right first molar, as shown in figure 1. in second molars, the concordance rate for antimeres was 74%. the hypocone expression of first molars compared with second molars was examined in 88 individuals. one member from each of the 88 twin pairs (i.e. twin a) was included in this analysis. as seen in table 2, almost all of the scores for the maxillary right first molar were larger than those for the right second molar, except for five subjects—three had a score of 5 on both first and second molars, one had a score of 4 on the first molar and score 4 on the second, and one had score 3 on the first molar and score 4 on the second. when examining the maxillary left molars, again, most of the scores on the first molar were larger than those on the second molar except for four individuals—three had a score of 5 on both first and second molars and one had a score of table 2: expression of hypocone trait on maxillary right first and second molars of individuals (one member of each twin pair)1 first molars score 0 1 2 3 4 5 total 0 0 1 0 1 5 2 9 1 0 0 0 1 17 5 23 2 0 0 0 0 8 2 10 3 0 0 0 0 16 8 24 4 0 0 0 1 1 17 19 5 0 0 0 0 0 3 3 total 0 1 0 3 47 37 88 1n= 88 second molars fig. 1. asymmetrical expression of hypocone trait on antimeric first molars—score 1 compared to score 4. fig. 2. example of reduction in hypocone size from first to second molars—score 4 to score 2. d. higgins et al. 5 4 on both first and second molars. a typical example of reduction in cusp size from the first to second molar is shown in figure 2. mz twin pairs exhibited a higher concordance rate for corresponding tooth comparisons than dz twin pairs, as shown in table 3. percentage concordance for the first molars between mz twin pairs was 80% whilst that for dz twin pairs was 67%. the concordance rate noted for the first molars was higher than that for the second molars, with the percentage concordance for the second molars being 65% for mz twin pairs and 22% for dz twin pairs. an ae model was the most parsimonious for all variables. there was no significant heterogeneity between sexes for variance components for hypocone score. the final models represent pooled data from both sexes. as an example, table 4 presents the pooled model structure and statistics for hypocone scoring of the upper right first molars only. table 5 presents narrow-sense heritabilities for hypocone score variability in the sample. all values were high and ranged between 0.87 and 0.93. the second molars had slightly higher estimates than the first molars. discussion in this study, the 6-grade scoring method developed by turner et al. (1991) for classifying hypocone expression was shown to be relatively easy to use and to provide consistent results. the intra-observer reliability of 98% was slightly higher than that of takahashi et al. (2007) who reported a concordance rate of 92% for scoring categories of hypocone expression on two separate occasions. the inter-observer assessment study showed a concordance of 70-74% which was similar to that found by nichol and turner (1986) who recorded concordance between observers of 70-75% for ranked traits (error rate 25-30%). the relative sizes of the cusps tended to correspond with phylogenetic and ontogenic timing of cusp formation. apart from one case, the hypocone was shown to be reduced from the maxillary first to second molar. the one exception could possibly be due to different crown morphology making scoring difficult. the overall results were consistent with previous cusp area studies (nichol and turner, 1986; macho and moggi-cecchi, 1992; takahashi et al., 2007) and support the morphogenic field concept of dahlberg (1945). as reported by takahashi et al. (2007) this study did not show any statistically significant difference in the occurrence of hypocones between males and females. however, this may be a reflection on the categorical system of classification used, which gives little information about actual size variation. this study did, however, show a tendency for higher frequencies of larger hypocone expressions in males than females. kondo et al. (2005) also reported that larger distal cusps were found in males rather than females. hence, it is table 3. percentage concordance observed for hypocone trait expression in dz and mz twin pairs right right left left tooth m1 m2 m1 m2 dz 67.4% 25.6% 67.4% 18.6% mz 80.0% 62.2% 80.0% 68.9% table 4. genetic model structure and associated statistics for hypocone scores on the maxillary right first molar1 parameterization n parameters -2 log likelihood df aic ace 176 7 255.9 170 -84 ade 176 7 256.0 170 -84 ae 176 6 256.0 171 -86 ce 176 6 260.8 171 -81 e 176 5 286.1 172 -58 1 abbreviations: n = sample size; df = degrees of freedom; aic = akaike’s information criterion table 5. narrow-sense heritability estimates (h2) for hypocone expression of maxillary molars in australian twins tooth1 h2 l 1 l 2 right first molar 0.87 0.65 0.96 left first molar 0.87 0.67 0.97 right second molar 0.90 0.80 0.95 left second molar 0.93 0.86 0.97 1h2 is heritability estimate; l 1 is lower 95% confidence limit of the h2 estimate, and l 2 is the upper 95% confidence limit. genetic influence on hypocone expression 6 likely that there is some influence of the sex chromosomes on the hypocone trait. hypocone expression was shown to be symmetrical between antimeric first molars except for one instance where the expression on the left was greater than the right, i.e. score 4 compared with score 1. a number of researchers have suggested that both sides of the dental arch are under the influence of common genetic factors (potter et al., 1976; baume and crawford, 1980). the findings of this study would support this hypothesis but the observed asymmetry in one individual would suggest environmental factors can lead to antimeric asymmetry. the fact that this study shows a lower rate of concordance for hypocone expression between right and left maxillary second molars than first molars relates well to the schedule of tooth development and the theory that there is an association between early crown formation and low morphological variation of the first molar (macho and cecchi, 1992). these findings support the contention that certain teeth in the dentition, generally the earlier-developing members of each tooth class, are under stronger genetic control than laterforming teeth that are more subject to environmental influences (corruccini and potter, 1981). it is assumed that mz twins share 100% of their genes but the similarities between them can be due partly to shared preand post-natal environment (scott and turner, 1997). common environment is perfectly correlated between twins in both zygosity groups whereas unique or non-shared environment only contributes to differences between twins. if genes are responsible for the expression of a trait, then a higher concordance of expression between mz twin pairs would be expected compared with that seen between dz twin pairs. this is what was noted in this study. however, although the concordance rate of expression of hypocones in mz twin pairs was higher than that in dz twin pairs, the concordance was not 100%. narrow-sense heritability estimates indicate the proportion of the phenotypic variation attributable to additive genetic effects. narrow-sense heritability is a measure of the degree to which individual phenotypes are determined by genes passed from parents to offspring, expressed as the ratio of the additive genetic variance to the total phenotypic variance. the high heritability estimates noted in this study suggest that most of the variation in expression of hypocones is due to genetic influences but environmental factors can still contribute to the observed variation. hypocones were universally present on first molars; the second molars demonstrated a greater range of phenotypic expression than the first molars, with absence noted in some individuals. this may suggest that there is a common genetic liability for hypocone expression on both the first and second molars, which is modulated by differences in size, location and/or developmental timing events between these teeth. in studies aimed at disclosing patterns in estimates of heritabilities, it has generally been assumed that the highest heritability will be displayed by the key tooth in each morphogenetic field (townsend et al., 2008). this was not noted in this study; in fact, slightly higher values were achieved by the second molar compared with the first. it is considered that the longer a cusp remains in its soft tissue stage prior to mineralisation the more likely phenotypic variation will occur since odontogenesis involves a series of complicated epigenetic and morphogenic events. (townsend et al., 2008). due to the relatively small variation in hypocone size on the first molars, only three categories were analysed (score 3 and below, score 4 and score 5), whereas when looking at second molars all six categories were considered. this difference in the categories of expression analysed between the first and second molars may have influenced the heritability estimates, contributing to the lower scores noted for the first molars. conclusions the hypotheses of this study were generally supported in that: 1. hypocone expression was more common and larger in maxillary first molars than second molars. 2. although sexual dimorphism was not statistically significant, there was a trend for males to have larger scores than females. 3. the expression of hypocones was symmetrical between antimeric teeth, with the concordance rates between sides being higher in first molars than second molars. 4. monozygotic twin pairs exhibited a higher concordance rate hypocone expression than dizygotic twin pairs. the results of model fitting and calculation of heritability estimates indicated that genetic factors exert a strong influence on hypocone expression in human maxillary molar teeth but environmental factors can also contribute to observed variance. acknowledgements the authors would like to particularly acknowledge dr zaliha ismail, who initiated this project but sadly was unable to see it through to publication. we also acknowledge the minister for police in south australia and the south australian police. this study also forms part of an ongoing investigation of the teeth and faces of australian twins and their families that is supported by the national health and medical research council of australia and the australian dental research foundation. the authors would like to thank the twins and their families who have agreed to participate in this research project and the australian twin registry for their continuing assistance. d. higgins et al. 7 literature 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determining the mode of transmission of semi-continuous traits. ann hum genet lond 36: 163-183. scott gr, turner cg ii.1997. the anthropology of human teeth. cambridge: cambridge university press. takahashi m, kondo s, townsend g, kanazawa e. 2007. variability in cusp size of human maxillary molars, with particular reference to the hypocone. arch oral biol 52:1146-1154. townsend g, harris ef, lesot h, clauss f, brook a. 2008. morphogenetic fields within the human dentition: a new, clinically relevant synthesis of an old concept. arch oral biol doi:10.1046/jarchoralbio.2008.06.011. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: advances in dental antropology. kelly ma, larsen cs, editors. new york: wiley-liss. p 13-31. genetic influence on hypocone expression liversidge 2010.3 16 many studies of dental maturation during the last 50 years have described the timing of permanent tooth formation stages. several reports remain important because they include very young children and follow individuals longitudinally (moorrees et al., 1963) or use clearly defined stages and a large sample (demirjian et al., 1973; demirjian and goldstein, 1976; demirjian and levesque, 1980; demirjian, 1994), although none give full descriptive results. the ease of statistical analyses and a better understanding of age estimation have highlighted the lack of descriptive data of the timing of tooth formation stages. this paper presents detailed results from a collaboration of published cross-sectional studies organised by nils chaillet in canada that has resulted in several published reports including a polynomial approach to demirjian’s dental maturity scale (chaillet et al., 2004; chaillet et al., 2005) and maturity data of individual tooth stages (liversidge et al., 2006). tooth formation data are presented here in different formats to assess maturity and estimate age using developing teeth in living children, in forensic cases, or in archaeological cases where sex is uncertain. material and methods tooth formation data from dental radiographs using demirjian stages (demirjian et al., 1973; 1976; demirjian, 1994) were combined to form the international data base. the sample consisted of cross-sectional data from published studies from finland, sweden, england, korea, belgium, australia, belgium, canada and france (nyström et al., 1986; nyström et al., 1988; kataja et al., 1989; liversidge and speechly, 2001; teivens and mörnstad, 2001; willems et al., 2001; mckenna et al., 2002; chaillet and demirjian, demirjian stage tooth formation results from a large group of children helen m. liversidge queen mary university of london, barts and the london school of medicine and dentistry, london, united kingdom correspondence to: helen m. liversidge, institute of dentistry, turner street, e1 2ad, london, united kingdom email: h.m.liversidge@qmul.ac.uk abstract the aim of this study is to present further data on the timing and variation of individual permanent mandibular teeth using demirjian stages from a large collaboration. seven mandibular permanent teeth were assessed from dental radiographs of healthy dental patients from australia, belgium, canada, england, finland, france, south korea and sweden (cross-sectional study; n = 9,371, 4,710 males, 4,661 females; aged 2–18). data are presented in three ways, namely by tooth stage for males, females, and pooled sex. mean age at entry of each tooth formation stage (maturity data) was calculated using logistic regression and modified for age prediction. the 51% confidence interval for age within stage of individual tooth stages was calculated for use in forensic age estimation where the burden of proof is on the balance of probabilities. average age, standard deviation, standard error, 3rd and 97th percentile within tooth stage was calculated from a uniform age sample (171 for each year of age from 3 to 16, n = 2,394). modified maturity data and average age within stage from the uniform age distribution are two new methods of age estimation. dental anthropology 2010;23(1):16-23. 2004). the sample studied in this paper, after cleaning was radiographic data from 4,710 males and 4,661 females aged 2 to 18 (when all individuals had reached second molar maturity) shown in figure 1 (left). previous results of the timing of demirjian tooth stages of individual teeth are available for males and females for each group separately (finland, sweden, england, korea, belgium, australia, belgium, canada and france) and for all groups combined for individuals from age 2 up to and including 16 years of age (table 9 in liversidge et al., 2006). mean age of entering a tooth stage was calculated by logistic regression for males, females and sexes combined (table 1). logistic regression calculates the average age at entry of a specific formation stage and represents the age when half of children at that age, have reached or passed the stage (taranger, 1976; eveleth and tanner, 1990; cameron, 2004) and is similar to probit regression used to calculate mean age of tooth eruption (liversidge, 2003). in this regard the mean age is identical to median age, half of children enter the stage prior to mean age, and half enter subsequent to mean age. this is an appropriate method to compare maturation between groups; it is not equivalent to the mean or median age of a child in the specific maturity stage (see below). maturity data were modified for each stage of each developing tooth (table 2) by adding half the interval to the next stage (see smith, 1991). the second way of presenting results is the 51% confidence interval of age 17 for each individual tooth stage. this was calculated using the 24.5th and 75.5th percentiles of average age within stage (table 10 from liversidge et al., 2006) and is shown in table 3. this is slightly greater than the inter-quartile range and just over half of individuals in the specific stage will fall within this interval. the third way data are presented is average age within stage from a uniform age sample. the age cohort with the lowest number of children was 171 for three year olds (87 male, 84 female) and 87 males and 84 females were randomly selected from each year of age from 3 to 16 (total n 2,394, figure 1 right). descriptive statistics of age within individual tooth formation stages, including 3rd and 97th percentiles (using the normal deviate, see cole, 2002) were calculated from this group and are shown in table 4. this is referred to as l10a in liversidge et al. (2010) in a comparison of dental age estimation methods using the same target sample of maber et al. (2006). results and discussion maturity data representing the average age entering a tooth formation stage (age when half of children have reached or passed the stage) are shown in table 1. the ages when 3% and 97% of girls and boys had entered some stages including d (crown complete with initial root) and h (mature apex) are shown in figure 2. the left and right hand edges of the open diamond are the ages when 3% and 97% of girls had reached or passed this stage. filled diamonds are data for boys. the sex difference is smaller for earlier stages and greatest for stage h (mature apex) of the canine. this is the only appropriate measure of the final maturity stage. smoothed cumulative frequency distribution curves are shown for m2 stages in figure 3. this is the only tooth in this study where data are available from crypt stage to mature apex; however the variation for early tooth stages is probably unrepresentative as fig. 1. age and sex of radiographic sample (left), selected group for a uniform age distribution (right). fig. 2. timing of some demirjian tooth stages including d (crown complete with initial root) and h (mature apex). diamond extends from 3rd to 97th percentile, apex is mean age. open diamonds females, solid diamonds males. this collaborative study includes only 38 two year olds. maturity data modified for age prediction are shown in table 2 (referred to as l9a in liversidge et al., submitted). once a tooth reaches the most mature stage (apex closed with mature periodontal ligament width) age cannot be estimated using development and this stage is omitted from tables of modified maturity data and within stage data. the second type of result is the 51% confidence interval (table 3, figure 4) similar to what koningsberg et al. (2008) term ‘coverage’. this interval is useful when estimating age in forensic cases where the burden of proof is on the balance of probabilities. coverage also demirjian tooth formation stages 18 males alone females alone sexes pooled mandibular mean for mean for mean for tooth grade prediction sd prediction sd prediction sd i1 e 4.39 0.44 4.24 0.42 4.33 0.43 f 6.02 0.38 5.70 0.36 5.88 0.38 g 6.97 0.40 6.68 0.37 6.82 0.39 h 8.35 0.60 7.84 0.57 8.09 0.60 i2 e 5.21 0.47 4.87 0.42 5.05 0.46 f 6.68 0.38 6.28 0.37 6.49 0.39 g 7.82 0.47 7.32 0.44 7.56 0.47 h 9.41 0.65 8.79 0.59 9.09 0.65 c d 4.75 0.59 4.19 0.53 4.49 0.59 e 6.60 0.45 5.99 0.44 6.31 0.47 f 8.51 0.51 7.59 0.50 8.04 0.56 g 11.04 0.61 9.84 0.56 10.42 0.67 h 13.23 0.64 11.73 0.68 12.47 0.80 p1 c 3.58 0.40 3.41 0.35 3.49 0.39 d 5.56 0.43 5.28 0.41 5.43 0.43 e 7.26 0.49 6.78 0.43 7.02 0.48 f 9.19 0.53 8.70 0.49 8.94 0.53 g 11.44 0.62 10.70 0.58 11.05 0.63 h 13.03 0.64 12.27 0.65 12.64 0.69 p2 b 3.81 0.57 3.80 0.55 3.81 0.56 c 4.94 0.55 4.81 0.55 4.89 0.55 d 6.48 0.57 6.21 0.56 6.35 0.57 e 8.02 0.58 7.62 0.64 7.82 0.62 f 9.83 0.69 9.35 0.60 9.58 0.65 g 12.26 0.75 11.57 0.71 11.90 0.76 h 14.09 0.73 13.44 0.76 13.77 0.78 m1 e 3.99 0.32 3.81 0.38 3.91 0.35 f 5.46 0.41 5.21 0.41 5.35 0.42 g 6.84 0.48 6.42 0.45 6.64 0.46 h 9.95 0.71 9.33 0.68 9.64 0.71 m2 o 3.40 0.30 2.92 0.51 3.19 0.40 a 3.46 0.33 3.33 0.42 3.40 0.37 b 3.97 0.33 3.72 0.46 3.87 0.38 c 4.91 0.44 4.85 0.44 4.88 0.42 d 6.79 0.52 6.43 0.54 6.61 0.54 e 8.80 0.56 8.48 0.52 8.64 0.55 f 10.68 0.60 10.12 0.56 10.39 0.60 g 12.18 0.60 11.57 0.60 11.86 0.63 h 15.22 0.71 14.75 0.77 14.99 0.75 table 1. mean age of entering demirjian tooth stages for mandibular permanent teeth recalculated from cleaned data using logistic regression of 4,710 males and 4,661 females1 1these statistics represent the age when half of children have reached or passed the stage. code o refers to crypt formation prior to evidence of tooth mineralization. provides a means to test if a target sample is representative (konigsberg et al., 2008); 24.5% should fall below the interval, 51% within the interval and 24.5% above. the third type of result is average age within stage from a uniform age distribution (similar number of individuals in each age category). konigsberg and frankenberg (1992) suggest that age could be more accurately estimated using a reference sample based on a uniform age distribution. results of this type from this study are shown in table 4 and are referred to as l10a in liversidge et al. (submitted). this flat age distribution, together with an adequate sample size and wide age range, are important features of a reference sample that contribute to accuracy (konigsberg and frankenberg, 2002; konigsberg et al., 2008). understanding how maturity data differ to within stage data is challenging and figure 5 illustrates some of these h.m. liversidge. 19 males alone females alone sexes pooled mandibular mean for mean for mean for tooth grade prediction sd prediction sd prediction sd i1 e 5.24 0.44 5.01 0.42 5.11 0.43 f 6.48 0.38 6.18 0.36 6.35 0.38 g 7.64 0.40 7.29 0.37 7.45 0.39 i2 e 5.94 0.47 5.62 0.42 5.77 0.46 f 7.20 0.38 6.86 0.37 7.02 0.39 g 8.56 0.47 8.06 0.44 8.32 0.47 c d 5.68 0.59 5.09 0.53 5.40 0.59 e 7.64 0.45 6.83 0.44 7.18 0.47 f 9.86 0.51 8.76 0.50 9.23 0.56 g 12.14 0.61 10.80 0.56 11.44 0.67 p1 c 4.61 0.40 4.37 0.34 4.46 0.39 d 6.34 0.43 5.99 0.41 6.22 0.43 e 8.20 0.49 7.82 0.43 7.98 0.48 f 10.32 0.53 9.83 0.49 10.00 0.53 g 12.24 0.62 11.49 0.58 11.84 0.63 p2 b 4.41 0.57 4.30 0.54 4.34 0.56 c 5.62 0.55 5.46 0.55 5.62 0.55 d 7.16 0.57 6.86 0.56 7.08 0.57 e 8.90 0.58 8.48 0.64 8.70 0.62 f 11.04 0.69 10.50 0.60 10.74 0.65 g 13.19 0.75 12.56 0.71 12.84 0.76 m1 e 4.80 0.32 4.58 0.38 4.63 0.35 f 6.20 0.41 5.81 0.41 6.00 0.42 g 8.38 0.48 7.84 0.45 8.14 0.46 m2 o 3.43 0.30 3.12 0.51 3.30 0.40 a 3.65 0.33 3.74 0.42 3.64 0.37 b 4.35 0.33 4.74 0.46 4.38 0.38 c 5.59 0.44 5.84 0.44 5.75 0.42 d 7.45 0.52 7.78 0.54 7.62 1.05 e 9.35 0.56 9.74 0.52 9.52 1.10 f 10.84 0.60 11.46 0.56 11.13 1.15 g 12.92 0.60 13.74 0.60 13.42 1.20 table 2. maturity data modified for age prediction for mandibular permanent tooth stages differences. smoothed cumulative distribution curves for stages d, e and f of m2 (sexes pooled) are shown. these curves represent the increasing proportion of children at each age who have reached or passed the specific stage. a tooth is considered to be ‘in’ a stage until it enters the next stage. the shaded area shows the age interval of all individuals within stage d; ranging from the youngest (most dentally advanced) to the oldest individual in that stage (most dentally delayed). maturity is a continuum and we arbitrarily divide this into discrete stages, even though the process of maturation is gradual. stage d in molars is defined as crown complete with initial root spicules visible at the mesial and distal edges. these root spicules increase in length and the root bifurcation becomes visible, firstly as a dot or line, then as a semi-lunar radio-opacity. once this occurs, the tooth is deemed to be in stage e. the three types of tooth data in this study are summarised in figure 5. mean age at entry for m2 stage d is shown as a dot, maturity data modified for age prediction for this stage is shown as a triangle. the age interval for individuals ‘in’ stage d, extends from the youngest child in stage d, up to the age when the most delayed child leaves this stage and enters the next stage (when all individuals have entered stage e). the age range of individuals within stage d and e are marked. the 51% age coverage for stage d is also shown. this figure was chosen for the forensic odontologist where the burden of proof is ‘on the balance of probabilities.’ this is an expression of the probability of estimated age being on one side of an age threshold. if an individual of unknown age presents with a second permanent molar in stage d (crown complete with initial root), the 51% age interval (from table 3) is 7.01 to 8.50. on the balance of probabilities, the age of this individual is older than six but younger than nine. the existence of population differences in dental maturity is unclear and uncertain. many studies report demirjian tooth formation stages 20 h.m. liversidge. males (n = 4,710) females (n = 4,661) combined (n = 9,371) tooth grade n 24.5% 75.5% n 24.5% 75.5% n 24.5% 75.5% i1 d 222 3.62 4.70 162 3.49 4.48 384 3.54 4.58 e 425 4.73 5.91 297 4.58 5.60 722 4.67 5.80 f 308 6.05 7.03 269 5.80 6.83 577 5.98 6.99 g 561 7.25 8.57 460 7.01 8.09 1021 7.10 8.30 i2 c 42 3.38 4.21 29 2.83 4.05 71 3.06 4.10 d 386 4.08 5.20 253 3.80 4.95 639 3.98 5.03 e 425 5.39 6.60 335 5.10 6.19 770 5.23 6.46 f 428 6.96 8.00 353 6.50 7.64 781 6.72 7.95 g 684 8.01 9.54 643 7.67 8.97 1327 7.90 9.10 c c 327 3.85 5.01 173 3.52 4.62 500 3.71 4.93 d 512 5.00 6.51 370 4.72 5.96 882 4.92 6.27 e 745 6.99 8.40 542 6.46 7.78 1287 6.79 8.06 f 1063 8.97 10.60 995 8.00 9.58 2058 8.43 10.06 g 800 11.02 12.97 817 10.00 11.65 1617 10.44 12.30 p1 a 20 2.57 3.34 21 2.59 3.33 b 69 3.33 4.26 55 3.01 3.79 124 3.10 4.07 c 433 4.38 5.44 308 4.18 5.28 741 4.28 5.40 d 554 5.95 7.20 406 5.60 6.95 960 5.78 7.05 e 803 7.67 9.00 795 7.20 8.53 1598 7.47 8.96 f 918 9.40 11.00 889 8.90 10.54 1807 9.05 10.92 g 580 11.32 12.97 657 10.63 12.10 1237 10.96 12.70 p2 o 10 2.39 4.92 16 2.67 4.52 a 89 3.54 4.72 77 3.30 4.44 166 3.45 4.60 b 222 4.27 5.21 160 4.19 5.33 382 4.23 5.23 c 446 5.17 6.68 338 5.06 6.48 784 5.10 6.58 d 570 6.70 8.10 494 6.61 7.96 1064 6.66 8.01 e 769 8.06 9.87 744 7.86 9.05 1513 7.99 9.46 f 945 9.98 11.97 969 9.64 11.39 1914 9.83 11.76 g 626 12.00 13.98 708 11.32 13.29 1334 11.70 13.74 m1 d 131 3.31 4.22 100 3.22 4.03 231 3.25 4.14 e 358 4.47 5.42 247 4.25 5.23 605 4.39 5.38 f 432 5.66 9.53 313 5.42 6.56 745 5.56 6.90 g 1279 7.70 9.53 1187 7.28 9.00 2466 7.50 9.20 m2 o 19 2.89 3.91 28 3.11 4.28 a 66 3.68 4.49 42 3.54 4.56 108 3.60 4.52 b 215 4.31 5.05 175 4.08 5.00 390 4.20 5.02 c 562 5.39 6.78 402 5.28 6.65 964 5.32 6.72 d 799 7.10 8.70 791 6.98 8.30 1590 7.01 8.50 e 794 8.98 10.48 734 8.57 10.01 1528 8.80 10.25 f 572 10.55 12.03 629 10.04 11.59 1201 10.25 11.97 g 983 12.53 14.50 1096 11.97 13.98 2079 12.02 14.11 table 3.fifty one percent coverage for mandibular tooth stages1 1this age interval includes 51% of individuals within each stage. stage included if n ≥ 10 significant differences in average age within tooth stage between groups, but this is inappropriate to compare maturity or average age at entry. for example, imagine if the minimum age of a study was 7 and the average age at entry of m2 stage d is calculated. looking at figure 5, this will exclude many individuals younger than 7 who have entered this stage. looking at the cumulative incidence curve for stage d, it is clear that more than half of 7 years old in this large study have m2 in stage d (or later), indicating that a minimum age of 7 is too old to calculate the average age for this stage. significant differences between groups have also been shown using a single dental maturity score such as nolla (nolla, 1960) or demirjian (demirjian et al., 1973; 1976; demirjian, 1994). these have been interpreted as due to either a secular trend or regional differences in dental maturation but little attempt has been made to investigate this more fully. there is little doubt that these differences occur, but it is questionable if they have any 21 differences and similarities indicate, but no clear pattern or developmental shift is evident. most studies of dental maturity are based on children of european origin. mean age at entry for individual tooth stages was compared in the groups of this collaborative study. children in canada, finland, sweden, belgium, england, france, australia and a small group from korea showed a wide age range of individuals within each tooth stage with many similarities in average age at entry (liversidge et al., 2006). no single tooth type was consistently earlier or later and no clear pattern emerged from this analysis. a comparison of mean age at entry of tooth stages by moorrees et al. (1963) on white and bangladeshi children aged 2 to 22 in london, united kingdom showed few significant differences in mean age between these ethnic groups (liversidge 2009). the lack of published data of dental maturity from other regions of the world is sparse, but being addressed. preliminary results from a worldwide comparative study showing stage h (apex mature) of the mandibular first molar in girls is shown in figure 7. smoothed cumulative distribution curves and 95% confidence interval of mean age (calculated from one year age groups using probit regression) are shown from the following regions: australian aboriginal (liversidge and townsend, 2006), inuit, japanese, maori and pacific islanders (moananui et al., 2008), south african black and cape coloured, uk, bangladeshi and white (liversidge, 2009). the most advanced girls (youngest) girls in this stage are 6 years old and by 12, almost all have reached this stage. the average age at entry, when 50% of girls have reached this stage, is similar between groups, although two groups are slightly earlier than the others. these similarities between the reference study and the present study and between world groups are supported by recent histological findings in the duration of crown formation (reid and dean 2006) between the past and the present. for instance, molar crowns take around 3 to 3.4 years to develop in maxillary, mandibular, first, second and third molars from medieval danes, northern european, south african black and north american groups (reid and dean, 2006). the largest permanent crowns are found in australian aborigines and the duration of enamel formation in molars in three first molars from this group is from 3 to 3.5 years (pers. comm. dj reid). despite little documentation of the rate of dentine growth and root formation between individuals or groups, these findings suggest that the time it takes to grow a tooth is similar across time and between groups, especially at the resolution of crown and root fractions from radiographs. assessing maturity or estimating age from crown and root stages is usually used for an individual child. in this regard the individual is compared to reference data while, in human biology, differences between groups are of interest. small differences in the mean age of individual tooth stages at the group level have little influence on the estimated age for an individual. population specific reference data of radiographic tooth stages may be fig. 3. smoothed cumulative distribution curves (proportion of individuals and age) for stages crypt to h for the permanent mandibular second molar (sexes pooled). fig. 4. age interval of 51% coverage for stages a to g of permanent teeth (pooled sex). biological meaning. the time interval between the original study demirjian et al. (1973) and the present collaboration is between twenty to forty years. mean age at entry of individual tooth stages in girls from the canadian reference (triangles apex at bottom; demirjian and levesque, 1980) and this study (triangles apex at top) are shown in figure 6. the largest differences occur as a single stage difference in four teeth; the earliest stage with data for both incisors and canine and the second stage for first premolars with mean age in the recent study being later than the original reference. the mean ages in subsequent stages in these teeth are similar or close in age. a comparison of the most mature stage in all tooth types is similar or marginally earlier in the recent study compared to the reference. it is unclear what these demirjian tooth formation stages 22 108-140. chaillet n, demirjian a. 2004. dental maturity in south france: a comparison between demirjian’s method and polynomial functions. j forensic sci 49:1059–1066. chaillet n, nyström m, demirjian a. 2005. comparison of dental maturity in children of different ethnic origins: international maturity curves for clinicians. j forens sci 50:1164-1174. cole tj. 2002. growth references and standards. in: human growth and development. cameron n, editor. san diego: academic press. p 383-413. demirjian a. 1993-94. dental development. cd-rom, silver platter education. montreal: university of montreal. demirjian a, goldstein h. 1976. new systems for dental maturity based on seven and four teeth. ann hum biol 3:411-427. demirjian a, goldstein h, tanner jm. 1973. a new system of dental age assessment. hum biol 45:211-227. demirjian a, levesque gy. 1980. sexual differences in dental development and prediction of emergence. j dent res 59:1110-1122. eveleth pb, tanner jm. 1990. worldwide variation in human growth. cambridge: cambridge university press. kataja m, nyström m, aine l. 1989. dental maturity standards in southern finland. proc finn dent soc 85:187-197. konigsberg lw, frankenberg sr. 1992. estimation of age structure in anthropological demography. am j phys anthropol 89:235-256. konigsberg lw, herrmann np, westcott dj, kimmerle eh. 2008. estimation and evidence in forensic anthropology: age-at-death. j forensic sci 53:541-557. fig. 5. a comparison of maturity data and within stage data. smoothed cumulative distribution curves for stages d, e and f for second molars are shown. mean age of attainment and modified for age prediction are shown as dot and triangle respectively. shaded area is the age interval of individuals within stage d. age range within stage d and e are shown as well as 51% age coverage for stage d. unnecessary and until evidence is available to show otherwise, the methods of age estimation presented here are appropriate for individuals from all groups. conclusions new data on the timing of demirjian stages from a large sample are presented in several ways. two of these (modified maturity data, average age within stage from a uniform aged group) are new methods appropriate to estimate age from individual permanent teeth. the 51% coverage age interval for individual tooth stages are described for forensic age estimation where the burden of proof is on the balance of probabilities. these results represent the biggest data set and therefore probably the most reliable maturity reference and age estimation methods for mandibular permanent tooth formation using demirjian stages in humans. acknowledgments i am particularly grateful to nils chaillet (chu saintejustine research centre, university of montreal, montreal, quebec, canada) for inviting collaboration and also marjatta nyström, hakan mörnstad, kian rowlings, jane taylor, guy willems and their co-authors for sharing data. literature cited cameron n. 2004. measuring maturity. methods in human growth research. in: hauspie rc, cameron n, molinari l, editors. cambridge: cambridge university press. p fig. 6. a comparison of mean age entering tooth stages for girls from demirjian and levesque (1980) triangles apex down and liversidge et al. (2006) triangles apex up. h.m. liversidge. 23 m al es ( n = 1 ,2 18 ) fe m al es ( n = 1 ,1 76 ) se xe s c om bi n ed ( n = 2 ,3 94 ) to ot h st ag e n m ea n sd 3r d 97 th n m ea n sd 3r d 97 th n m ea n sd se m 3r d 97 th i1 d 11 1 3. 96 0. 61 2. 81 5. 11 10 8 3. 85 0. 57 2. 78 4. 92 21 9 3. 90 0. 59 0. 04 2. 79 5. 01 e 14 4 5. 18 0. 88 3. 53 6. 83 12 0 5. 01 0. 81 3. 49 6. 53 26 4 5. 10 0. 85 0. 05 3. 50 6. 70 f 83 6. 50 0. 83 4. 94 8. 06 81 6. 19 0. 71 4. 86 7. 52 16 4 6. 35 0. 78 0. 06 4. 88 7. 82 g 12 3 7. 94 * 1. 13 5. 82 10 .0 6 10 4 7. 54 0. 85 5. 94 9. 14 22 7 7. 76 1. 03 0. 07 5. 82 9. 70 i2 c 28 3. 83 0. 52 2. 85 4. 81 15 3. 57 0. 49 2. 65 4. 49 43 3. 74 0. 52 0. 08 2. 76 4. 72 d 16 6 4. 38 * 0. 80 2. 88 5. 88 14 0 4. 13 0. 70 2. 81 5. 45 30 6 4. 26 0. 76 0. 04 2. 83 5. 69 e 12 2 5. 86 * 0. 88 4. 21 7. 51 12 7 5. 58 0. 80 4. 08 7. 08 24 9 5. 72 0. 85 0. 05 4. 12 7. 32 f 95 7. 42 * 1. 07 5. 41 9. 43 94 7. 00 0. 86 5. 38 8. 62 18 9 7. 21 0. 99 0. 07 5. 35 9. 07 g 14 2 8. 61 1. 23 6. 30 10 .9 2 12 0 8. 35 0. 92 6. 62 10 .0 8 26 2 8. 49 1. 10 0. 07 6. 12 1 0. 56 c c 14 3 4. 16 0. 83 2. 60 5. 72 97 3. 93 0. 65 2. 71 5. 15 24 0 4. 07 0. 77 0. 05 2. 62 5. 52 d 16 6 5. 51 * 0. 98 3. 67 7. 35 16 2 5. 07 0. 99 3. 21 6. 93 32 8 5. 29 1. 01 0. 06 3. 39 7. 19 e 16 6 7. 51 * 0. 99 5. 65 9. 32 13 1 6. 91 0. 87 5. 27 8. 55 29 7 7. 25 0. 98 0. 06 5. 41 9. 09 f 22 2 9. 90 * 1. 31 7. 44 12 .3 6 18 9 8. 86 1. 05 6. 89 10 .8 3 41 1 9. 42 1. 30 0. 06 6. 98 11 .8 6 g 19 1 12 .1 2* 1. 24 9. 79 14 .4 5 14 9 10 .9 1 1. 24 8. 58 13 .2 4 34 0 11 .5 9 1. 38 0. 07 9. 00 1 4. 18 p 1 b 40 3. 75 0. 57 2. 68 4. 82 39 3. 54 0. 47 2. 66 4. 42 79 3. 65 0. 53 0. 06 2. 65 4. 65 c 16 3 4. 59 0. 82 3. 05 6. 13 15 0 4. 46 0. 76 3. 03 5. 89 31 3 4. 53 0. 79 0. 04 3. 04 6. 01 d 15 3 6. 32 * 0. 89 4. 65 7. 99 13 1 6. 08 0. 99 4. 22 7. 94 28 4 6. 21 0. 95 0. 06 4. 42 8. 00 e 16 2 8. 21 * 1. 06 6. 22 10 .2 0 16 6 7. 85 0. 92 6. 12 9. 58 32 8 8. 02 1. 01 0. 06 6. 12 9. 92 f 20 2 10 .3 7* 1. 35 7. 83 12 .9 1 16 0 9. 83 1. 12 7. 72 11 .9 4 36 2 10 .1 3 1. 28 0. 07 7. 72 1 2. 54 g 15 1 12 .2 5* 1. 27 9. 86 14 .6 4 13 3 11 .7 4 1. 20 9. 48 14 .0 0 28 4 12 .0 1 1. 26 0. 07 9. 64 1 4. 38 p 2 a 47 4. 07 0. 75 2. 66 5. 48 49 3. 80 0. 60 2. 67 4. 93 96 3. 93 0. 69 0. 07 2. 63 5. 23 b 84 4. 44 0. 72 3. 09 5. 79 71 4. 46 0. 86 2. 84 6. 08 15 5 4. 45 0. 79 0. 06 2. 96 5. 94 c 14 4 5. 79 * 0. 99 3. 93 7. 65 11 6 5. 44 0. 85 3. 84 7. 04 26 0 5. 64 0. 95 0. 06 3. 85 7. 43 d 12 1 7. 20 1. 11 5. 11 9. 29 13 3 7. 15 1. 01 5. 25 9. 05 25 4 7. 18 1. 06 0. 07 5. 19 9. 17 e 15 9 9. 08 * 1. 33 6. 58 11 .5 8 14 3 8. 60 1. 16 6. 42 10 .7 8 30 2 8. 85 1. 27 0. 07 6. 46 11 .2 4 f 21 6 11 .1 1* 1. 55 8. 20 14 .0 2 17 2 10 .6 8 1. 26 8. 31 13 .0 5 38 8 10 .9 2 1. 44 0. 07 8. 21 1 3. 63 g 16 8 13 .1 0* 1. 48 10 .3 2 15 .8 8 15 6 12 .5 0 1. 35 9. 96 15 .0 4 32 4 12 .8 1 1. 45 0. 08 10 .0 8 15 .5 4 m 1 d 89 3. 94 1. 00 2. 06 5. 82 70 3. 68 0. 53 2. 68 4. 68 15 9 3. 83 0. 83 0. 07 2. 27 5. 39 e 12 4 4. 76 0. 73 3. 39 6. 13 11 1 4. 53 0. 72 3. 18 5. 88 23 5 4. 65 0. 73 0. 05 3. 28 6. 02 f 11 3 6. 20 * 0. 88 4. 55 7. 85 10 0 5. 78 0. 82 4. 24 7. 32 21 3 6. 00 0. 88 0. 06 4. 35 7. 65 g 28 6 8. 55 * 1. 55 5. 64 11 .4 6 27 2 8. 14 1. 32 5. 66 10 .6 2 55 8 8. 35 1. 46 0. 06 5. 61 11 .0 9 m 2 o 11 3. 45 0. 32 2. 85 4. 05 17 3. 61 0. 41 0. 10 2. 84 4. 38 a 43 3. 80 0. 43 2. 99 4. 61 26 3. 75 0. 44 2. 92 4. 58 69 3. 78 0. 43 0. 05 2. 97 4. 59 b 88 4. 56 0. 65 3. 34 5. 78 88 4. 39 0. 83 2. 83 5. 95 17 6 4. 48 0. 74 0. 06 3. 09 5. 87 c 16 2 5. 93 0. 95 4. 14 7. 72 13 3 5. 68 0. 88 4. 03 7. 33 29 5 5. 82 0. 93 0. 05 4. 07 7. 57 d 16 6 7. 80 1. 19 5. 56 10 .0 4 17 6 7. 53 1. 05 5. 56 9. 50 34 2 7. 66 1. 13 0. 06 5. 54 9. 78 e 16 7 9. 74 1. 28 7. 33 12 .1 5 13 7 9. 38 1. 13 7. 26 11 .5 0 30 4 9. 58 1. 22 0. 07 7. 29 11 .8 7 f 13 5 11 .5 6* 1. 14 9. 42 13 .7 0 12 0 10 .9 8 1. 05 9. 01 12 .9 5 25 5 11 .2 9 1. 13 0. 07 9. 17 1 3. 41 g 26 0 13 .6 3* 1. 45 10 .9 0 16 .3 6 26 4 13 .2 4 1. 48 1 0. 46 16 .0 2 52 4 13 .4 4 1. 48 0. 06 10 .6 6 16 .2 2 t a b l e 4 . a ve ra ge a ge o f c hi ld re n w it hi n a s ta ge fr om a u n if or m a ge d is tr ib u ti on o f 8 7 m al es a n d 84 fe m al es fo r ea ch y ea r of a ge 3 -1 6. u n de rs co re m ea n s ag e n ot si gn ifi ca n tl y di ff er en t be tw ee n s ex es . a st er is k m ea n s ag e si gn ifi ca n tl y di ff er en t (p < 0 .0 1) b et w ee n s ex es . demirjian tooth formation stages 24 liversidge hm. 2003. worldwide variation in human dental development. in: thompson jl, nelson a, krovitz g, editors. growth and development in the genus homo. cambridge: cambridge university press. p 73-113. liversidge hm. 2008. dental age revisited. in: irish jd, nelson gc, editors. technique and application in dental anthropology. cambridge: cambridge university press. p 234-265. liversidge hm. 2009. permanent tooth formation as a method of estimating age. front oral biol 13:153-157. liversidge hm, chaillet n, mörnstad h, nyström m, rowlings k, taylor j, willems g. 2006. timing of demirjian tooth formation stages. ann hum biol 33: 454-470. liversidge hm, smith bh, maber m. 2010. bias and accuracy of age estimation using developing teeth in 946 children. am j phys anthropol (doi:10.1002/ ajpa.21349). liversidge hm, speechly t. 2001. growth of permanent mandibular teeth of british children aged 4-9 years. ann hum biol 28:256-262. liversidge hm, townsend g. 2006. tooth formation in australian aborigines. in: zadzinska e, editor. current trends in dental morphology research. lodz: university of lodz press. p 405-410. maber m, liversidge hm, hector mp. 2006. accuracy of age estimation of radiographic methods using developing teeth. forensic sci int 159:s68-73. mckenna cj, james h, taylor ja, townsend gc. 2002. tooth development standards for south australia. aust dent j 47:223–227. moananui rt, kieser ja, herbison p, liversidge hm. 2008. advanced dental maturation in new zealand maori and pacific island children. am j hum biol 20:43-50. moorrees cfa, fanning ea, hunt ee. 1963. age variation of formation stages for ten permanent teeth. j dent res 42:1490-1502. nolla cm. 1960. the development of the permanent teeth. j dent child 27:254–266. nyström m, haataja j, kataja m, evalahti m, peck l, kleemola–kujala e. 1986. dental maturity in finnish children, estimated from the development of seven permanent mandibular teeth. acta odontol scand 44:193–198. nyström m, ranta r, kataja m, silvola h. 1988. comparisons of dental maturity between the rural community of kuhmo in north eastern finland and the city of helsinki. commun dent oral epidemiol 16:215–217. reid dj, dean mc. 2006. variation in modern human enamel formation times. j hum evol 50:329-346. smith bh. 1991. standards of human tooth formation and dental age assessment. in: kelly ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss. p 143-168. taranger j. 1976. evaluation of biological maturation by means of maturity criteria. acta paediatr scand 258, suppl, 77-82. teivens a, mörnstad h. 2001. a comparison between dental maturity rate in the swedish and korean populations using a modified demirjian method. j forensic odontostomatol 19:31–35. willems g, van olmen a, spiessens b, carels c. 2001. dental age estimation in belgian children: demirjian’s technique revisited. j forensic sci 46:893–895. fig. 7. preliminary results of maturation of stage h of the mandibular first molar from world regions. left: smoothed curves (proportion of girls vs. age). right: 95% confidence interval of mean age for australian aborigine, inuit, japanese, maori and pacific islanders, south african black, south african cape coloured, uk bangladeshi, uk white girls. h.m. liversidge. 3 dental anthropology 2018 │ volume 31 │ issue 02 linear enamel hypoplasia in permanent dentition of children in the late archaic and the late prehistoric river valley emily moes 1* and samantha h. blatt 2 1 university of new mexico, usa 2 idaho state university, usa keywords: linear enamel hypoplasia, ohio river valley, perikymata, agriculture the intensification of agriculture often corresponds to an increase in skeletal indicators of physiological stress and growth disruption relative to hunter-gatherers in similar environments (cohen and armelagos, 1984; cohen, 1989; steckel and rose, 2002; larsen, 2006; ungar et al., 2017). for example, at dickson mounds, illinois, multiple indicators show increasing levels of nutritional stress and infectious disease with the rise of maize agriculture (goodman and armelagos, 1988; kent 1986). however, this trend is not universal (e.g. winterhalder and kennett, 2006). hutchinson and larsen (1988) find that stress experiences among native americans of st. catherines island, georgia increase in duration over time, despite similarities to previous agriculturalists in maize consumption. the authors argue this is likely due to disease and social changes introduced by the arrival of spanish missionaries. therefore, generalizations about the well-being of archaeological populations are not synonymous with their subsistence strategies. life course hypotheses regarding response to early life stressors are dependent on accurate documentation of duration of stress episodes and the ages at which they occurred in order to better contextualize interpretations (temple et al., 2013; temple, 2014). hutchinson and larsen (1988) showed that information about stress episode duration could alter interpretations of the relationship between subsistence strategy and physiological stress. physiological stress during development results in disruption of enamel formation (hillson, 1992), creating enamel defects that are permanently archived in the tooth crown. bioarchaeologists consider these defects to be non-specific indicators of stress attributable to causes including psychological factors, fevers, malnutrition, infection, and trauma (armelagos et al., 2009; roberts and manchester, 2005). while the crown of a tooth is forming, enamel matrix is secreted continuously by ameloblasts in successive layers starting at the crown of the tooth. successive growth layers are differentiated by striae of retzius (hillson, 1996). striae are temporally divided by cross-striations, which represent a circadian rhythm of growth, each accounting for 24 hours of growth (fitzgerald, 1995; hillson, 2005; lacruz et al., 2012; reid and dean, 2006). therefore, when cross striations are counted between striae of retzius, the timing in days, or periodicity of the striae, can be determined. externally, these striae correspond to circumferential structures that are visible on the surface of the tooth, known as perikymata (antoine and hillson, 2016; hillson, 1996; fitzgerald, 1995). therefore, as enamel is laid down in successive layers, each perikyma represents a abstract the intensification of agriculture is often correlated with an increase in physiological stress, but this relationship is not always clear and needs to be examined in biocultural context. this project compares the timing and duration of stress events of foragers (4000-3000 b.p.) with those of agriculturalists (a.d. 1000-1500) by analyzing linear enamel hypoplasia (leh) on the permanent anterior teeth of 40 children from late archaic and late prehistoric ohio river valley. scanning electron microscopy was used to create photomontages of the tooth surfaces. prevalence, frequency, and duration of leh were compared between samples using fisher’s exact tests and pairwise anova. results indicate that agriculturalist children endured the highest prevalence and frequency of stress events; although, forager children endured longer durations of stress events. variation in stress experiences may be attributed to the nutritional transition to maize consumption and food storage during the late prehistoric period. however, a period of increased conflict, population aggregation, and political shifts from interaction with mississippians are also discussed as contributing factors. *correspondence to: emily moes university of new mexico albuquerque, new mexico 87110 emilymoes@unm.edu 4 dental anthropology 2018 │ volume 31 │ issue 02 period of development in days, as reflected by the periodicity, or cross-striation count. when a systemic stress event occurs, energy is diverted away from ameloblasts, causing a deficit in matrix secretion and the enamel volume, interrupting the normal distribution of perikymata (hillson, 1992). the result is an increased distance between successive perikymata. these physiological disruptions during growth produce localized defects on the enamel surface, which can occur as pits, furrows, or planes (hillson, 2005). linear enamel hypoplasia (leh) is the most recognizable and commonly reported form of enamel defect (hillson and bond, 1997; ten cate, 1994), and takes the form of a horizontal line or linear array of pits on the enamel surface (goodman and rose, 1990; hillson, 1996). the width of leh is the result of the number of affected perikymata; therefore, representing a quantification of the duration of stress events (antoine and hillson, 2016; hubbard et al., 2009). the appearance of leh is further influenced by its location on the tooth surface since perikymata are more widely spaced near the occlusal/apical surface and more densely packed at the cervix. this means that leh near the crown cervix of an incisor, for example, will appear narrower compared to its matching defect on a canine, which will appear in the middle of the crown. matched defects will often appear at different locations when using two different teeth due to differences in the timing of enamel development. regardless of their locations on two or more teeth, defects that form in response to the same systemic stress are composed of the same number of striae of retzius and perikymata (antoine and hillson, 2016; hillson and bond, 1996). the occlusal wall of leh represents the period during which the stress event occurred, while the cervical wall represents the period of recovery (guatellisteinberg, 2008; hillson and bond, 1997). the association of leh with perikymata thus correlates with the chronological development of the tooth enamel. in tooth cusps, striae of retzius dome over each other and do not outcrop on the surface. as compared to posterior teeth, anterior teeth are the most useful to examine for leh because more of their enamel surface is covered by perikymata (goodman and armelagos, 1985; hillson and bond, 1997; guatelli-steinberg et al., 2012). this study reconstructs patterns of growth disruption of permanent teeth of subadults using incremental microstructures to examine leh prevalence, frequency, duration, and age of occurrence among temporally distinct populations with different subsistence strategies (foraging and agricultural) within the prehistoric ohio valley. linear enamel hypoplasia prevalence, frequency, and duration measure different aspects of the stress experience. prevalence indicates the proportion of people in a sample who were affected by a physiological growth disturbance during childhood. frequency reflects the average number of growth disruptions that any one person in the sample is likely to have experienced. lastly, leh duration is an indication of how long an individual was affected by a single growth disruption. in other words, leh duration reflects the amount of time until that person began recovering from such an incident. therefore, discordance of leh prevalence, frequency, and stress episode duration is possible, though not always expected. with the advent of agriculture in north america, maize became an important subsistence staple, although it varied regionally in the rate of adoption (e.g. cassidy, 1984; cook and schurr, 2009; goodman and rose, 1984; sciulli and oberly, 2002). isotopic analysis from numerous sites within the ohio river valley indicate rapid incorporation of maize in the diet in the late prehistoric period (1100 – 400 b.p.) with intensified agriculture (greenlee, 2002). although maize meets daily caloric requirements, it is a poor source of amino acids and protein (spielmann and angstadt-leto, 1996; whitney and rolfes, 2011). the phytates and plant proteins in maize inhibit iron absorption, and niacin in maize binds to glucose molecules, decreasing their bioavailability (baynes and brothwell, 1990; mackay et al., 2012). the nutritive value of maize is also altered during food processing further removing important minerals and fiber depending on the processing protocols (rylander, 1994). if absorption or consumption of iron and other nutrients is low, anemia could result, leading to susceptibility of disease and infection (dubos, 1965; scrimshaw, 1964; 2003). it is often assumed that maize gruel was introduced to infants around six months of age in late prehistoric populations, when growth needs begin to exceed the nutrients supplied in breast milk (wright, 1997). even though breast milk was likely still a significant component of an infant’s diet during this time, maize gruel may not have been sufficient in providing supplementary nutrients. therefore, throughout the weaning process, leh may represent stresses initially caused by nutritional deficiency (blakey et al., 1994). bone remodeling is also influenced by nutritional stresses and disease (frost, 2003), and an increase in remodeling per unit area can indicate greater health risk (cho and stout, 2003). nutritional problems are synergistically bound to the frequency of infection since ubiquitous pathogens can become increasingly virulent under the influence of decreased host resistance due to poor nutrition (dubos, 1965; scrimshaw, 1964; 2003). greater remodeling rates in maize agriculturalists compared to foragers have been recorded from lower illinois river valley sites and other locations (stout, 1983; stout and lueck, 1995; stout and teitelbaum, 1976). these greater rates may reflect nutritional stress of a low protein maize diet. in the ohio river valley, perzigian et al. (1984) and 5 dental anthropology 2018 │ volume 31 │ issue 02 cassidy (1984) studied stress indicators and dietary transitions, respectively, from archaic (6000 – 3000 b.p.) to late prehistoric (1100 – 400 b.p.) periods. dental caries and attrition show the greatest difference in populations through time in the ohio valley (sciulli and oberly, 2002). maize agriculturalists exhibit higher frequencies of dental caries and increased frequencies of pathological conditions such as periapical lesions and antemortem tooth loss (sciulli and oberly, 2002). although these conditions are a byproduct of age, the earlier appearance and elevated frequencies of dental caries among agriculturalists has been largely attributed to the increased consumption of dietary carbohydrates (larsen, 2006; selwitz et al., 2007). materials the sample for this study consists of photomontages of cast replicas of the immature (i.e. incomplete enamel growth) permanent anterior dentition of 40 subadults from three archaeological assemblages: the duff, buffalo, and sunwatch sites (figure 1). the histologically determined ages at death of individuals in the sample range from 2.23 – 10.06 years (duff), 1.57 – 6.45 years (buffalo), and 1.09 – 7.15 years (sunwatch) (calculated in blatt, 2013). poor preservation of subadult remains in the archaeological record in this area contributed to the limited sample size. sites chosen for study also display a significant degree of genetic homogeneity (sciulli, 1990; sciulli and oberly, 2002) thereby reducing the potential for variability in the data due to genetic factors. therefore, we assume that any discrepancies in dental growth and development among the present samples are attributable to individual variation and/or environmental influences. in addition to the age distribution of well-preserved subadults, the three sites were selected for their regional consistency and the well-studied archaeological and biological contexts they provide. given the body of research on the increased disease load that is often associated with the rise of maize agriculture (e.g. cohen and armelagos, 1984; larsen, 2006), we first predicted that the agricultural samples in this study would exhibit a statistically significant increase in physiological stress as measured by a higher prevalence and frequency of leh compared to the foraging sample. second, we predicted that these stress episodes would last longer among the agriculturalists due to the assumed persistence of pathogens among a large, sedentary population. third, we hypothesized that agriculturalist children would exhibit the earliest age of first leh occurrence because a weaning diet supplemented by maize porridge is more likely to lead to malnutrition and systemic stress earlier in development than a foraging diet that includes a broader spectrum of foods and essential nutrients (ungar et al., 2017). overall, the objectives of this study were to assess change across time in the stress experiences that impacted prehistoric children of the ohio river valley in association with subsistence and social transitions. a total of 31 individuals, of 40 originally sampled, had adequately developed and preserved enamel microstructures for the purposes of this study. individuals were included if they had at least 40% of the enamel present on their incisors (blatt, 2013). subadults under the age of two years were excluded from analyses for this reason (reid and dean, 2000). deciduous teeth were excluded since they do not consistently display perikymata. we excluded teeth with taphonomic changes and/or excessive wear to limit error in perikyma counts that would skew chronological assessment. duff site (n=9) the duff site (22lo111), located in the mid-western area of ohio (see figure 1), consists of a relatively large and complete cemetery (sciulli and aument, 1987). radiocarbon dates of 2,950 ± 155 years b.p. and 3100 ± 40 years b.p. from skeletal material indicate that the site was used for a short period of time during the terminal late archaic (ca. 3000 – 2500 b.p.) (sciulli and aument, 1987; sciulli, 1990). during this time, populations lived in small scattered groups at seasonal habitation sites subsisting through hunting and gathering (parmalee, 1969). the dietary breadth of the duff people centered on diverse faunal assemblages, nut harvesting, wild plants, and riverine resources (emerson et al., 2009; parmalee, 1969). domesticates, such as maize, were neither produced nor consumed during this period, as supported by isotopic and arfigure 1. map of ohio showing the locations of the sites used in this study. 6 dental anthropology 2018 │ volume 31 │ issue 02 chaeological evidence (stothers and bechtel, 1987). the migratory nature of hunting and gathering populations allowed for the occupation of seasonal habitation sites, reducing the risk of resource depletion and nutritional deficiency. sciulli and aument (1987) report high young adult mortality, and low infant mortality among individuals at the duff site. warming from the hypsithermal period is believed to have decreased the carrying capacity in the region during the latter part of the late archaic, but populations appear to remain stable (ford, 1977). buffalo (n=18) the buffalo site (46pu31) is located along the banks of the kanawha river in buffalo, west virginia (see figure 1). it was hastily excavated between 1963-1965 (hanson, 1975), during which some burials were avoided, crushed, and displaced by bulldozers (drooker, 2000). the site consisted of permanent settlements inhabited year-round, spanning several temporal/cultural traditions from the archaic to the late prehistoric (1000-1500 a.d.) (hanson, 1975). for the purposes of this study, only the latter period, which encompasses fort ancient, will be discussed since sample materials from buffalo date from this time. fort ancient is considered a regional culture of kinstructured villages that responded similarly to varying degrees of mississippian influence (cook, 2008; cowan, 1986; griffin, 1943; henderson and turnbow, 1987; turnbow and sharp, 1988). the fort ancient occupation of the site is seen in two overlapping villages and burials clustered in groups near house structures (hanson, 1975). from the original excavations, very little information is reported about subsistence or social stratification at buffalo. many charred hickory nuts and walnuts were recovered from the site, and it appears that deer were brought back to the site for butchering. there is no reported evidence for other plants used at the site; although, numerous remains of mammals and birds were recovered (hanson, 1975). nevertheless, it is commonly assumed that the subsistence economy at buffalo was associated with horticulture or less intensive agriculture (e.g. blatt, 2013; hanson, 1975; sciulli and oberly, 2002). isotope data (13c/ 12c) of mid-late prehistoric remains throughout the region indicates that maize was by far the most consumed food by the fort ancient people. late prehistoric ohio valley populations also tended to have shorter stature, a lower life expectancy, and higher infant (1-3 years) mortality than earlier huntergatherers (cassidy, 1972; 1984). such changes in mortality patterns are also likely related to the overall increase in population size and sedentism from archaic to late prehistoric populations in the region. sunwatch (n=13) contemporary with buffalo, sunwatch (33my57) village is the most extensively excavated and analyzed fort ancient site and is the type site of middle fort ancient (a.d. 1200-1400) (heilman et al., 1988; henderson and pollack, 2001). sunwatch is located along the great miami river, three miles south of dayton, ohio (see figure 1). the site is comprised of a wellplanned circular village, concentric circles of clustered burials, storage pit structures, and houses that were organized outwardly around a red cedar center pole (heilman et al., 1988). this organization is thought to be part of a solar alignment system, and culminating in a stockade around the periphery (heilman and hoefer, 1981). relative to hunting and gathering groups, this period is marked by increases in sedentary population size, social complexity, regional integration, and extra-regional trade (dunnell, 1971; drooker, 1997; essenpreis, 1978; griffin, 1943). subsistence focused on a maize-intense diet. however, supplementary hunting and gathering was still employed (rossen, 1992). carbon isotope analysis reveals no difference between males and females in maize consumption. however, nitrogen isotope analysis shows that females ate less meat than males (conrad, 1988). agricultural populations tended to have shorter stature, a lower life expectancy, and high infant mortality compared with hunter gatherers (cassidy, 1984). large fort ancient sites, like sunwatch, consumed more maize than smaller villages, but the highest carbon isotope levels were most closely associated with sites that had the highest number of mississippian goods and structures (cook and schurr, 2009; schurr and schoeninger, 1995). research on the degree and consistency of mississippian interaction with fort ancient villages is contentious, as some authors conclude that the fort ancient development was necessarily stimulated by the mississippians (griffin, 1943; cook, 2012), while others deny any significant influences (pollack and henderson, 2000). there is significant evidence for mississippian reach at sunwatch (cook, 2008; 2012). skeletal trauma and mortuary iconography that have been associated with warfare and peace keeping among mississippian leaders, such as the inclusion of dog burials and symbolism associated with mississippian dog soldiers, appear in one quadrant of the site, which is otherwise segmented by kin groups (cook, 2012). development of war leadership and presence of foreign soldiers in the village fit well with the escalating conflicts in the greater region (milner et al., 2001). in a study of intracemetery biological variation using dental metrics, sciulli and cook (2016) found that sunwatch consisted of a primary late woodland population with some nonlocal mississippian individuals, who were highly 7 dental anthropology 2018 │ volume 31 │ issue 02 related to the late woodland population. the authors suggested that acculturation accounted for mississippian cultural characteristics in southwestern ohio or that gene flow, accounting for the genetic similarities between fort ancient and mississippian peoples, occurred before 800 b.p. (sciulli and cook, 2016). during the occupation of sunwatch, fort ancient sites were becoming more aggregated, as mississippian sites became smaller (drooker, 1997; cook and aubry, 2014). it is likely that these mississippians migrated into the hinterland of fort ancient villages, influencing political and sociocultural transitions at villages such as sunwatch (cook, 2012; cook and aubry, 2014). an influx of foreign elite leaders (as evidenced from burial inclusions and comparisons) and reshuffling of populations from patrilocal residence patterns to matrilocal could have significantly increased adult and developmental stress, nutritional stress, and pathogen load from overcrowding, as compared to other sites used in this study (cook, 2012; cook and aubry, 2014). methods high resolution cast replicas were made of the labial surface of anterior teeth. photomontages were created using a fei nova nano scanning electron microscope (sem) 400 at 50 times magnification (blatt, 2013). replicas, histological data from sectioned teeth (discussed below), photomontages, and age estimation used in this study originate from the work of blatt (2013). perikymata were identified as regularly spaced grooves running horizontally across the surface. linear enamel hypoplasia was identified as an accentuated area in which perikymata were spaced more widely relative to those around them (guatelli-steinberg, 2008). accentuation was first identified subjectively relative to adjacent perikymata. imagej (rasband, 19972017) was then used to metrically verify the increase in width from scaled images (figure 2). from the photomontages available, we were unable to evaluate enamel depressions in order to identify leh (as in king et al., 2002; temple, 2014; 2016). nevertheless, there was limited bias in leh identification and perikymata counting because most individuals in the sample died prior to cervical enamel formation, which is the area most affected by tightly “packed” perikymata. because we did not often have perikymata available to count near the cervix, we did not apply hassett’s (2012) method. however, since metric comparison of width variations among adjacent perikymafigure 2. photomontage example. lower left canine of individual b6-71 from sunwatch with arrows indicating leh (and accentuation in the horizontal perikymata). leh a includes 6 perikymata, leh b and c both have two perikymata each. occlusal surface is towards the top. modified from blatt (2013). 8 dental anthropology 2018 │ volume 31 │ issue 02 ta was not performed along the entire enamel surface, leh prevalence and frequency data represent minima for each sample. the method of recording leh used in this study has been applied to other sites in the study region (martin and sciulli, 2008; steckel et al., 2002) and should produce comparable data. perikymata were counted from the occlusal/apical end until the onset of each accentuation. this procedure eliminated any visual confusion thereby minimizing intra-observer error. perikymata of each tooth were counted twice at least one week apart and the mean number of perikymata was used as the final count result (blatt, 2013). we matched defects between two anterior teeth from each individual in order to eliminate any defects associated with localized trauma. defects were matched by comparing duration, interval between successive defects, and the histologically derived estimate from enamel microstructures of the age at onset for each hypoplasia on each tooth (blatt, 2013). frequency was calculated for each individual by counting the average number of matched leh occurrences among the anterior teeth. individuals with two anterior teeth with observable defects were categorized as leh positive. to calculate prevalence, the number of leh-positive individuals was divided by the total number of individuals with at least two observable anterior teeth and is presented as a percentage. the interval between successive defects was recorded as the number of perikymata from the beginning of one leh to the start of the next. subsequently, perikymata were counted within each accentuation to establish the duration of each leh event (hubbard et al., 2009). duration was expressed as the number of all perikymata affected by a growth disruption. although hillson and bond (1997) argue that the duration of growth disruption should be evaluated as the number of perikymata in the occlusal wall of a defect, the total number of affected perikymata was used as an indirect indicator of stress duration since the transition between occlusal and cervical walls was often not clear. as such, stress episode duration in this study includes the periods of disruption and recovery (guatelli-steinberg et al., 2005). stress duration was calculated as the total number of perikymata, as defined above, multiplied by the periodicity (blatt, 2013). periodicity (number of days represented by each perikyma from each population) was determined in two ways: either by direct counts of cross striations between striae of retzius, or by measuring the length (in μm) between adjacent striae of retzius divided by the local mean daily secretion rate (blatt, 2013). a modal periodicity of eight days (for n = 7 teeth) was determined for the sample through histological analysis by blatt (2013). to calculate the ages at which stress events occurred, the total number of perikymata from the occlusal surface of each tooth to the beginning of each identified leh was counted and multiplied by the periodicity. this total was then added to the initiation times (reid and dean, 2006; blatt, 2013), representing the age at which tooth calcification begins. subsequently, mean cuspal enamel formation time (determined by blatt, 2013) was added, representing the time since initiation and first perikyma outcropping, for each specific tooth. the sum of these values and the developmental timing of all perikymata was then subsequently divided by 365.25 to yield age of occurrence in years. the age of occurrence of subsequent defects were calculated by adding the number of days between defects (duration plus interval) to the age of occurrence of the previous defect. ages ranges at death (with correction factors) for all individuals in this study were previously provided through microstructural and histological analyses by blatt (2013). it has long been agreed upon and thoroughly tested that microscopic methods provide more accurate age estimates than those using macroscopic methods (fitzgerald and rose, 2008; stringer et al., 1990); therefore, many of the estimations normally required for assessment of age and duration of leh were eliminated. since it is unknown if the subsistence economy at buffalo focused as intensely on maize agriculture as at sunwatch, the samples from these sites are considered separately rather than pooled. to control for possible bias in defect duration comparisons that could have been caused by amount of mineralized enamel available for observation, the samples were separated into two groups: those who died before 3.5 years, and those who died after 3.5 years. blatt (2013) found that ohio valley children completed crown development for all incisors by 3.5 years (ranged 3.13 – 3.5 years). as such, groups were divided by enamel completion such that the younger subadults had at least 40% of enamel visible (blatt, 2013). defect prevalence for each site is not affected by this sectioning since all individuals under the age of two were excluded from analyses. prevalence was compared between samples using a fisher’s exact test in the statistical computing environment r (r core team, 2013). box plots were produced to depict ranges of stress episodes. stress episode duration and age at first occurrence were compared between the samples using a one-way anova with tukey’s hsd test for each pairwise comparison. overall, these tested the similarities and differences in the stress experiences of huntergatherers relative to agriculturalists in the prehistoric ohio valley. 9 dental anthropology 2018 │ volume 31 │ issue 02 results of the 14 individuals from buffalo, 12 (85.7%) presented hypoplastic defects. prevalence among sunwatch individuals was similar; eight of the nine (88.9%) subadults displayed at least one enamel hypoplasia while those from the duff site exhibited a prevalence of four out of eight (50%). frequency of leh for the buffalo and sunwatch sites was also similar, with 1.8 and 1.89 defects per tooth respectively. the smallest frequency was observed from duff individuals, with an average of 1.125 defects per tooth. notably, no more than three defects were matched between anterior teeth on any individual from any site. a summary of the prevalence and frequency results for all subadults are given in table 1. despite differences in prevalence, fisher’s exact tests showed that they did not differ significantly between the three sites nor between any two (table 2). when individuals were pooled, the duration of stress episodes, given in days representing growth disruption and recovery, varied widely within each group (table 3, figure 3). the individuals from the duff site experienced a longer average duration than those from buffalo or sunwatch. duff individuals endured stress episodes for an average of 45.75 days, whereas those from buffalo and sunwatch endured an average of 34.9 and 25.22 days respectively. tukey’s hsd test suggested subadults from the sunwatch site experienced significantly shorter stress episodes than those from the duff site (p = 0.021). there was no significant difference between duff and buffalo (p = 0.292) nor between sunwatch and buffalo (p = 0.172). conversely, when considering the average duration of leh for each child, instead of average duration in each group, anova showed no significant difference between samples (p = 0.122). when comparing subadults between sites who died before the age of 3.5 years (see table 1), tukey’s hsd test showed there was a significant difference in the duration of stress episodes only between buffalo and sunwatch children (p = 0.03), due to the outlier seen in figure 4, whose leh lasted for 98 days. when considering those who died after the age of 3.5 years, duration of stress episodes among duff children was significantly longer than both buffalo (p = 0.003) and sunwatch durations (p = 0.018) (figure 5). duration of stress episodes between sunwatch and buffalo children older than 3.5 were not significantly different (p = 0.822). anova indicates no significant difference in age at first occurrence between the three groups (p = 0.374). the ages at which subadults from all samples experienced their first stress episode began between 0.89 and 2.67 years. table 3 shows the ages at which each stress episode occurred, and the duration of each event. age ranges are given for each leh using the standard deviation values for each tooth, from blatt (2013). the consistency of multiple leh occurrences within the second and third years of life among the sunwatch sample prompted an investigation of the interval between leh. the average times between successive leh: 115.6 days at duff; 155.43 days at buffalo; and 86 days at sunwatch. discussion although leh prevalence among the buffalo and sunwatch children was higher than in the duff sample, this difference was not statistically significant, suggesting that a similar proportion of individuals were subjected to physiological stress, despite subsistcomparison x 2 p b, d, s 4.953 0.119 b, s 0.025 1.000 d, b 1.980 0.131 d, s 1.496 0.131 table 2. results of the fisher's exact tests. d = duff; b = buffalo; s = sunwatch. table 1. leh prevalence and frequency for all individuals in each site site total prevalence pooled ages ages < 3.5 years age > 3.5 years average leh frequency total observed number with defects total observed number with defects total observed number with defects duff 50.00 1.13 8 4 4 3 4 1 buffalo 85.70 1.80 14 12 7 6 7 6 sun watch 88.90 1.89 9 8 7 6 2 2 10 dental anthropology 2018 │ volume 31 │ issue 02 site individual id age at death (years) leh a age (years) leh a duration (days) leh b age (years) leh b duration (days) leh c age (years) leh c duration (days) d u ff b19 10.06 2.67 78 3.03 3.12 52 3.36 3.49 58 b37 2.93 1.29 18 1.63 1.80 22 b45 2.6 1.64 b75a 2.93 1.68 32 1.81 58 2.07 48 b u ffa lo d10-b24 2.71 2.06-2.11 24 2.31-2.37 72 d10-b38 6.12 1.42-1.67 14 d11-b27 2.36 1.27-1.31 28 1.56-1.58 22 d12-b9 3.15 2.5 2.62 28 3.32 3.63 24 e7-b12 2.76 2.56 30 2.85 28 e8-b18 5.06 1.01 20 1.27 32 e8-b76 6.45 0.99 1.08 20 1.74 54 2.24 2.26 50 e8-b82 5.06 1.98 2.16 14 2.36 2.58 24 e9-b10 5.81 1.25 1.33 22 1.69 1.85 26 e10-b43a 3.53 1.12 1.29 36 1.84 40 2.47 22 e10-b110 2.91 1.31 1.47 40 f10-b20 2.87 0.97 42 1.22 66 1.54 98 b3-74 2.99 1.84 2.00 8 s u n w a tc h b6-71 4.16 1.92 42 2.05 18 2.19 2.23 20 b6-73 2.87 1.38 1.47 16 1.45 1.57 28 1.54 1.65 40 b6-80 2.67 0.89 1.06 8 1.12 1.28 24 1.51 1.68 42 b10-80 2.32 1.43 1.58 14 b11-76 2.65 1.98 2.04 14 2.04 2.14 28 2.29 28 b13-72 7.15 1.56 1.84 36 2.39 2.56 44 b14a-72 2.98 1.85 1.88 24 2.14 2.24 20 table 3. age at occurrence for each leh by site given in years, with the duration of each episode given in days. ranges represent the possible age at which stress episode first began, where individual numbers represent the only viable age at which the episode could have begun, given the age overlap between the observed teeth. age at death is also presented for each individual. figure 3. stress episode duration given in days for all individuals, the whiskers indicate 95% confidence intervals. figure 4. stress episode duration given in days for individuals who died before the age of 3.5 years, the whiskers indicate 95% confidence intervals. figure 5. stress episode duration given in days for individuals who died after the age of 3.5 years, the whiskers indicate 95% confidence intervals. 11 dental anthropology 2018 │ volume 31 │ issue 02 ence strategy differences and aggregation hazards in late prehistory. the average number of defects per tooth was lowest among the duff sample, supporting the first hypothesis that the agricultural groups experienced a higher frequency of stress episodes. average duration of leh defects was significantly different between duff and sunwatch, where duff children experienced longer stress episodes than sunwatch children. here, the duration analysis refutes the second hypothesis because foragers in this study endured longer stress episodes than did maize agriculturalists. these results suggest that duff children experienced physiological stress less often than those at buffalo or sunwatch. however, stress episodes lasted longer at duff than at the other two sites. discord between leh prevalence, frequency, and duration is seen in other studies that use leh to examine stress differences in archaeological samples. for example, temple et al. (2013) found that despite greater leh frequencies among jomon period foragers from hokkaido, japan, they had significantly shorter stress episode durations than tigara inupiat from point hope, alaska. in another study, greater stress episode duration was evident in modern inuit compared to neandertals from krapina, despite similar leh prevalence within each sample (guatellisteinberg et al., 2004). king et al. (2005) found significant differences in leh prevalence between females from two historic london cemeteries, although there were no significant differences between duration or frequency of stress episode. these studies attribute the differences in stress experiences to seasonal variation in food availability and/or dietary quality between their samples. the third hypothesis regarding a significant difference in age at first occurrence between agriculturalists and foragers was rejected. this result reflects the susceptibility of children in the first years of life to system stress, regardless of subsistence strategy. many previous studies have linked the presence of leh after the first year or so of life to the negative effects of weaning (e.g. coppa et al., 1995; corruccini et al., 1985; ogilvie et al., 1989; ubelaker, 1992; webb, 1995). however, since other elements leading to enamel defects include nutritional problems, illness, or poor hygiene, weaning may not be the sole factor leading to growth arrest in enamel during the first year of life (see blakey et al., 1994; katzenberg et al., 1996). variation between prevalence, frequency, and duration may be attributed to differences in subsistence strategy, dietary breadth, and transitions in population size or mississippian influences and migration. the dietary breadth of the duff people (emerson et al., 2009; parmalee, 1969) suggests that children had access to foods with sufficient macroand micronutrients, possibly helping to mitigate continuous nutritional inadequacies, resulting in reduced leh frequency. however, due to a lack of food surplus and storage (parmalee, 1969), if climate or seasonal variations occurred causing food depletion or relocation, duff individuals may have experienced longer episodes of physiological stress. indeed, climate warming impacted the region during the late archaic during the hypsithermal period (ford, 1977), but detailed analysis of climatic changes is lacking in the literature. the increased frequency of stress episodes observed in both sunwatch and buffalo children supports previous studies suggesting an increase in chronic systemic disturbances in late prehistoric agricultural populations (e.g. cassidy, 1984; cook, 1984; danforth, 1999; mummert et al., 2011; larsen, 2006; sciulli and oberly, 2002). it is common to also compare stature between groups as an indirect indicator of stress. specifically, numerous archaeological remains have shown a reduction in stature and decline in overall health with the introduction of intensive agriculture (cook, 1984; danforth, 1999; mummert et al., 2011; larsen, 2006; scuilli and oberly, 2002; temple, 2010). however, trends in stature reduction and the foragingagriculture transition are not universal. many studies have shown a decrease in juvenile stature with the rise of agriculture (e.g. mummert et al., 2011), while others show no change, an increase, or an increase in regional variability in stature (e.g. steckel and rose, 2002; temple, 2011). sites from the lower illinois river valley do not indicate adult stature changes through time or subsistence transitions, even though there is evidence of reduced juvenile stature (cook, 1984). children from all sites in this study have also been shown to have achieved a lower percentage of attained growth progression of femur length at each age relative to the mean attained growth achieved by the children from the denver growth study and columbus morgue samples (maresh, 1955; sciulli, 1994; sciulli and blatt, 2008). additionally, significant differences (p = 0.001) were reported between skeletal age and dental age between the children in these three sites (blatt, 2013), indicating compromised physiological growth despite biological age. sunwatch results also support indications of systemic early life or prenatal stresses reported from enamel defects of deciduous teeth (martin and sciulli, 2008). while decreased host resistance is likely to have contributed to the increase in leh frequency in the buffalo and sunwatch subadults, a diminished quality of diet is unlikely to be the only cause of an increase in frequency of stress episodes. although an understanding of the extent of mississippian influence at fort ancient sites, like sunwatch, is currently evolv12 dental anthropology 2018 │ volume 31 │ issue 02 ing, patterns of increased conflict and migration in the region are serious means of stress-inducing events to consider when comparing growth disruption through time. intensive agriculture at sunwatch allowed for population growth and sedentism, especially for the influx of mississippian migration, which afforded ample opportunity for the introduction and perpetuation of novel pathogens (goodman et al., 1984; larsen, 1995). increased maintenance of diseases and other pathogens relative to hunting and gathering groups may be a cause of the shortened intervals between successive stress episodes in the sunwatch children. in contrast to duff individuals, the analysis of stress episode duration in this study suggests sunwatch children experienced shorter episodes of physiological stress. there are some limitations and future explorations that should be considered within the framework of this project. first, the most evident issue is the small sample size. juvenile remains from the archaeological record are often sparse and generally poorly preserved when compared to adult remains. it was difficult to obtain a sizeable sample, even from multiple sites. compounding the problem, the sample was further reduced by omitting some individuals due to the presence of only one anterior tooth where at least two were needed to be considered for analysis. additionally, as mentioned above, enamel deposition is not linear in the permanent dentition (fitzgerald, 1995; hillson and bond, 1997; reid and dean 2000). the beginning of a hypoplastic defect is typically identified as the point where a perikyma is more widely spaced than its occlusal neighbors. yet, the spacing between each successive perikyma can be variable through different parts of the same tooth since perikymata are packed more tightly in some areas compared to others (schwartz et al., 2001). in order to accurately calibrate the spacing between perikymata across differently packed areas, the mean distance and standard deviation would ideally be calculated based on the nearest neighbors (hassett, 2012). however, a reliable and definitive study of dental enamel via microscopic analysis requires expensive analytical tools that are impractical in many field and laboratory situations compared. for many researchers, it is more reasonable, instead, to assess interobserver reliability of dentition that had limited variation in perikymata “packing”, as in this study. finally, it is noteworthy that enamel hypoplasias can be observed only on those individuals who survived the stress events, and what cannot be known is if the children died during another episode, or due to some other cause. markers of disease or deprivation in human remains represent only a fraction of the health disruptions in a population since most diseases will not leave lesions on bone, or will abate or kill their hosts before being expressed on skeletal tissue (wood et al., 1992). conclusions the results of this study indicate observable differences in leh frequency and duration between the duff, buffalo, and sunwatch subadults. our first hypothesis was confirmed; the agricultural samples reflected an increase in physiological stress through higher leh frequencies and prevalence than those observed in the foraging sample (see table 1). contrary to the second hypothesis, the stress experiences of duff children lasted longer than those of sunwatch or buffalo, possibly due to differences in resource storage in cases of resource depletion or climate variations. in this case, sunwatch children relied on protein-deficient maize in a populated environment ripe for spreading pathogens, whereas duff children had access to a more balanced diet in a sparsely populated environment. an alternative explanation for the differences in the health experiences of hunter-gatherers and agriculturalists is that late archaic (duff) populations did not possess the techniques, practices, or support for sick individuals. in the case of the duff population, in which groups were initially becoming larger and less mobile, a sedentary lifestyle was probably in its early stages of development, which would have increased the propensity for pathogens to spread (sciulli and oberly, 2002). with that in mind, individuals inflicted with a potentially life-threatening illness may have been more likely to die in a short time, leaving skeletons, or their teeth, unmarked by acute effects of illness. there is a trend for hunting and gathering populations in the eastern woodlands to exhibit fewer pathological conditions on their skeletons and teeth as compared to sedentary populations who assumedly had established techniques and support for ill people (sciulli and oberly, 2002; steckel et al., 2002). on average, in the former populations, individuals with obvious effects of disease did not live as long. conversely, in groups with well-developed care practices, like that at sunwatch, individuals would have had a better chance of surviving acute phases of disease. as such, these populations would have had longer lives (sciulli and oberly, 2002). therefore, if chronic phases of diseases were to develop, they would manifest in their skeletal remains. expansion of this project should explore these trends by supplementing this analysis with the inclusion of adult skeletal materials to assess health within the life course approach (agarwal, 2016). ideally, the childhood stress experiences archived in leh should be examined in individuals who survived childhood in order to assess potential links between childhood 13 dental anthropology 2018 │ volume 31 │ issue 02 stress and health in later life. a greater understanding of the long-term impact of subsistence and social transitions in the ohio river valley would also benefit from comparison of adult attained stature with frequency of leh observed in adults. the assumption being that increased leh is correlated with having shorter adult stature and shorter lives as the result of childhood stress. temple (2014) assessed future risk of stress from early life stress. such patterns have been demonstrated in recent studies (amoroso et al., 2014; temple, 2014; watts, 2013) but samples from north america have not yet been applied to this model to aid in this complicated discourse. nevertheless, the study of stress patterns in children is important for narrating the life course of young shortened lives. acknowledgments this project was supported by the wenner-gren dissertation fieldwork grant, larsen grant through the department of anthropology at the ohio state university, graduate research and scholarship grant through the ohio state university graduate school, sigma xi grant-in-aide-of –research, and dan montgomery research grant from boise state university. sem images were generated using the instruments and services at the campus microscopy and imaging facility, the ohio state university. we are also grateful to the dayton, ohio american indian advisory committee for access to the sunwatch collection and for permission for destructive analyses. paul sciulli, robert cook, clark larsen, and debbie guatellisteinberg were instrumental in the seminal doctoral research of this project and of providing regionally specific insight. a special thank you to the editor, the two reviewers, and alexis o’donnell for all of their helpful feedback on this manuscript. references agarwal, s.c. 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(1992). enamel hypoplasia in ancient ecuador. in a.h. goodman, l.l. capasso (eds.). recent contributions of the study of enamel developmental defects (pp. 207-217). journal of paleopathology, monographic publications, no. 2. ungar, p.s., crittenden, a.n., & rose, j.c. (2017). toddlers in transition: linear enamel hypoplasias in the hadza of tanzania. international journal of osteoarchaeology, 27, 638-649. watts, r. (2013). childhood development and adult longevity in an archaeological population from barton-upon-humber, lincolnshire, england. international journal of paleopathology, 3, 95-104. webb, s. (1995). paleopathology of aboriginal australians: health and disease across a hunter-gatherer continent. cambridge, uk: cambridge university press. whitney, e.n., & rolfes, s.r. (2011). understanding nutrition, twelfth edition. belmont, ca: cengage learning. winterhalder, b., & kennett, d.j. (2006). behavioral ecology and the transition from hunting and gathering to agriculture. in d.j. kennett, b. winterhalder (eds.). behavioral ecology and the transition to agriculture (pp. 1-21). berkeley: university of california press. wood, j.w., milner, g.r., harpending, h.c., & weiss, k.m. (1992). the osteological paradox: problems of inferring prehistoric health from skeletal samples. current anthropology, 33, 343-370. wright, l.e. (1997). intertooth patterns of hypoplasia expression: implication for childhood health in the classic maya collapse. american journal of physical anthropology, 102, 233-247. lease 2013.6 45 there have been very few studies focusing solely upon the morphology of the deciduous dentition. analyses of the deciduous dentition are usually included as part of a larger study of the permanent dentition, (e.g. aguirre et al. 2006) or as an archaeological study (e.g. sciulli 1998). a few examples of population studies on the deciduous dentition include jørgensen (1956), hanihara (1968), sciulli (1977, 1990, 1998), harris (2001), grine (1986) and lease (2003). rarely has african american dentitions been described independently. the present study examines 25 morphological traits of the deciduous dentition in three samples: two african american samples from memphis, tn and dallas, tx (n= 218) and a european american sample (n=100) from cleveland, oh. these traits represent the most commonly used traits in population microevolution studies, describing various ancestral groups. the goal of the study is to provide a description of deciduous trait presence and trait variation within the african american samples. materials morphological data were collected from a total of 318 individuals from three samples representing two ancestral groups: african and european. the african american children are represented by 117 individuals from memphis, tennessee and 101 individuals from dallas, texas. the european american children are represented by 100 individuals from cleveland, ohio. data were collected from two sources: dental stone casts and photographs. dental casts were the primary resources for the memphis, tn and the cleveland, oh samples. the dallas, tx sample comprises of 5”x7”photographs taken in a professional laboratory (condon et al. 1998). casts were included in the study if they met the following criteria: morphological features were a descriptive study of african american deciduous dentition loren r. lease department of sociology, anthropology, and gerontology, youngstown state university, youngstown, ohio 44555 keywords: dental morphology, biological ancestry, asudas abstract descriptive studies of the deciduous dentition morphology have been presented as an inclusion in permanent dentition studies, the focus of archaeological populations or on specific traits within modern populations. the present study describes 25 morphological traits of deciduous dentition in two african american samples from memphis, tn and dallas, tx (n= 218), and a european american sample (n=100) from cleveland, oh. these traits represent the most commonly used traits in population microevolution studies, describing various ancestral groups. results indicate trait frequency variation between the two african american samples, as well as in comparison to european american samples. traits varying in frequency between the two sample populations include maxillary lateral incisor shovel shape trait (69% vs. 46%), canine tuberculum dentale (40% vs. 22%), canine mesial ridge (3% vs. 7%), and maxillary posterior molar hypocone development (76% vs. 92%). trait frequencies higher than found in previous studies include maxillary central incisor shovel shape trait (38%) and maxillary lateral incisor shovel shape trait (68%), canine tuberculum dentale (40%), maxillary molar complexity (20%), cusp six (33%) and seven (68%), and the y-groove on the mandibular posterior molar (69%). trait frequencies seen lower in previous studies include tuberculum dentale trait on both maxillary incisors (8% and 3%) and the hypocone development of the maxillary posterior molar (76%). the level of trait expression is informative when comparing populations, especially the molar traits. for example, carabelli’s pit/ fissure is the most common trait expression in african american samples, unlike european american samples. correspondence to: loren r. lease department of sociology, anthropology, and gerontology, youngstown state university, youngstown, ohio, 44555 lrlease@ysu.edu 46 clearly visible, there were clear separations between teeth, there was no stretching of the cast or chipping of the cast and at least one member of the antimere was present (lease 2003). photographs were included in the study if the morphology was clearly visible and no caries were present. edgar (2002) tested the viability of using two different materials and found fewer morphological traits were visible for photographs; intra-observer error is no different than twice observing the same dentition in the same format. the children (57 females and 60 males) who comprise the memphis sample were routine dental patients seen during the 1990s at the pediatric dental department of the university of tennessee, memphis (lease and harris 2001). the majority of the children resided in the “greater metropolitan area of memphis” which includes suburban and urban areas around memphis. the socioeconomic status was described as middle class and they had access to health care at the university of tennessee medical center (ef harris, personal communication, 2003). ancestry identification was determined by parents. the dallas, tx sample consisted of 101 children buried in the freedman’s cemetery, the sex of whom was unknown. individuals buried at the freedman’s cemetery were residents of urban dallas. the cemetery was active from 1867 to 1907, with the majority of excavated burials dating from 1900 to 1907 (condon et al. 1998). juveniles in the study lived post-slavery (hjh edgar, personal communication, 2003). all socioeconomic statuses available to african americans at the time are represented. the european american sample was collected at the school of dentistry, case western reserve university from the bolton-brush longitudinal growth study. ancestry came from parental determination. data was collected on 50 males and 50 females born between 1920 and 1945 (bailey 1992). the children resided in the urban areas of cleveland, oh and were described as having access to good health care, education and nutrition (bailey 1992). methods morphological data consists of the scores of 25 deciduous traits. these 25 traits represent the most commonly used traits in micro-evolutionary studies and are the basis for creating dental morphological complexes describing various ancestral groups (jørgensen1956, hanihara 1963, hanihara 1966, hanihara 1967, grine 1986, sciulli 1998). a complete description of expressions and traits can be found in lease (2003). morphological data were collected following sciulli (1998). when present, both the right and left teeth of each individual were scored. if the expression of the antimeres was the same, that score was used as the expression of the tooth. if the score of a trait was different between the antimeres, the more complex expression was used to represent the tooth. if only one tooth was present, that expression was used to represent the tooth. no root traits were collected due to the principle sources (casts and photographs). in the analysis and discussion of the morphological traits, the use of the term “deciduous molar” reflects the historic or traditional usage in dental anthropology and the scoring procedures (lease 2003). ontologically these teeth are premolars (sciulli 1998). analysis statistical analyses were performed in sas version 8.02. the range of variation for each trait was calculated by expression frequencies for each sample. the weighted average expression (w) was calculated for each feature: w = (scixi/sxi). ci is the expression value and xi is the number of individuals with that expression. the weighted average is one method that captures where the range of variation within the sample lies. for example, the morphological trait of shovel shape for the maxillary central incisor has four expressions: 0, 1, 2, 3. the weighted average for this trait in the cleveland sample is 1.15. ixi i)= ((0*28)+(1*40)+(2*21)+(3*11))/100 =1.15. therefore, dichotomization into absence/ presence frequencies is between the expression class 1 and expression class 2 for the maxillary central incisor. the second analysis was performed to calculate the dichotomization of frequencies of the morphological traits. dichotomization (presence/absence) frequencies should reflect the weighted averages for each trait. 47 table 1. frequency counts and weighted averages the presence/absence frequency of a trait was calculated as in the following example using the shovel shape of the deciduous maxillary central incisor: shovel shape : ui1 0 absent: lingual surface smooth 1 semi-shovel: slight 2 shovel: marginal ridges present 3 strong shovel: marginal ridges broad and wide expressions 0 and 1 were designated as the absence of the shovel shape trait and expressions 2 and 3 were designated as the presence of the trait in the individuals. the frequency of the trait (presence) in the population can then be expressed at p = 2-3 / 0-3, with 2-3 as the number of individuals having the expression 2 or 3 and 0 to 3 being the total number of individuals scored (sciulli 1998). the presence frequencies for the anterior dentition traits among the three samples were tested for significance using student’s t test (tables 3-5). expression frequencies for the posterior dentition were tested for significance (tables 6-8). results of the original 25 traits, nine traits had minimal variation within the samples (table 1). these traits were: double shoveling, interruption grooves (for both the maxillary and mandibular central and lateral incisors) and posterior mandibular molar number. these traits were eliminated from further analyses.the remaining 16 traits were dichotomized for each sample either by absence/ presence (i.e. shovel shape) or by the feature expressed (i.e. carabelli’s cusp vs. pit) (table 2). five of the 12 anterior traits (table 3) are significantly different for the cleveland and memphis samples. the memphis sample has greater percentage for the maxillary lateral incisor and mandibular canine shovel shape trait. the cleveland sample has greater frequency for the maxillary incisors tuberculum dentale and maxillary canine distal ridge. the analyses of the posterior traits are found in table 6. the majority of the traits examined for cleveland and memphis indicate that the memphis sample exhibits higher frequencies for the more complex expressions. regarding hypocone trait expression cleveland memphis dallas n= 100 n= 117 n=101 i 1 ss 0 1 2 3 w 28 40 21 11 1.15 30 35 25 9 1.13 42 21 26 12 1.46 i 2 ss 0 1 2 3 w 10 39 28 22 1.63 31 35 39 11 1.26 31 23 31 15 1.30 ucss 0 1 2 3 w 14 38 34 14 1.48 35 30 36 16 1.28 38 26 25 13 1.13 i1ss 0 1 2 3 w 91 5 4 0 0.13 69 4 1 2 0.16 81 7 4 5 0.26 i2ss 0 1 2 3 w 67 26 6 1 0.58 80 17 4 2 0.30 69 11 11 10 0.62 lcss 0 1 2 3 w 34 44 19 3 0.91 48 36 17 12 0.94 45 18 22 16 1.09 i 1 ds 0 w 99 0.00 100 0.00 98 0.00 i 2 ds 0 w 98 0.00 114 0.00 97 0.00 ucds 0 1 2 w 94 2 3 0.08 114 1 0 0.01 98 1 1 0.03 i 1 interruption groove 0 2 w 100 0 0.00 100 1 0.01 98 0 0.00 48 table 1., cont’d . development, cleveland has higher frequencies for only having the eocone and protocone present (corresponding to hanihara’s (1963) maxillary first molar morphology of 2), memphis has higher frequencies of 4 and 5 (hanihara’s (1963) 3h and 4 -/4) for the maxillary anterior molar. similar results are seen for the maxillary posterior molar. the memphis sample has higher frequencies of the accessory cusps 6 and 7, as well as more cusps on the mandibular anterior molar. in addition, the individuals within the sample have higher frequencies of deflecting wrinkle and a pit/groove for the proto-stylid and the y-5 molar pattern. for carabelli’s trait, in the cleveland sample the trait is more likely to be absent or a cusp, and in the memphis sample,a pit. with regards to the mandibular posterior groove patterns, the cleveland sample more often exhibited the + pattern and memphis the y pattern. comparing cleveland and dallas samples frequencies of 11 of the 12 anterior traits (table 4) are significantly different between the cleveland and dallas samples. dallas has higher percentages for maxillary and mandibular central incisor shovel shape trait, mandibular lateral incisor and canine shovel shape trait and maxillary canine mesial ridge. cleveland has higher presence rates for the maxillary lateral incisor shovel shape, the maxillary incisor and canine tuberculum dentale and the maxillary canine distal ridge. similar results are found for the analyses of the posterior traits for the cleveland and dallas samples (table 7) with a few exceptions. unlike the cleveland/memphis analysis of carabelli’s trait, there is no statistical significance between the cusp frequencies for cleveland and dallas samples. comparing memphis and dallas samples when comparing the two african american samples, four of the 12 traits are significantly different (table 5). the memphis sample shows the shovel shape trait more often for the maxillary lateral incisor and canine, while the dallas samples has higher frequencies of that trait in the mandibular central and lateral incisors. when comparing the posterior dentition traits (table 8) for the two african american samples,there are small differences in frequency expressions. the memphis sample has higher frequencies for the less complex expression for hypocone development for both maxillary molars, while dallas is statistically significant for the more complex development expressions. memphis trait expression cleveland memphis dallas n= 100 n= 117 n=101 i 2 interruption groove 0 w 99 0.00 115 0.00 97 0.00 i 1 td 0 1 2 3 w 78 17 3 0 0.23 94 3 3 0 0.09 92 6 1 1 0.11 i 2 td 0 1 2 w 83 15 1 0.17 110 3 1 0.04 96 2 1 0.04 uctd 0 1 2 3 w 44 29 25 2 0.85 69 13 33 0 0.69 79 6 13 4 0.35 ucmr 0 1 2 3 w 98 1 0 1 0.01 114 2 1 0 0.03 96 4 2 1 0.11 ucdr 0 1 2 3 4 w 88 9 1 1 1 0.18 109 7 0 0 0 0.06 100 1 1 0 0 0.03 lcdr 0 1 2 3 4 w 99 0 1 0 0 0.02 112 1 3 1 0 0.09 101 0 1 0 0 0.02 49 trait expression cleveland memphis dallas n= 100 n= 117 n=101 m 1 hypocone 2 3 (3m1 & 3m2) 4 (3h1 & 3h2) 5 (4&4) w 61 22 12 5 2.61 16 22 57 20 3.70 3 19 60 20 3.95 m 2 hypocone 3 (3a) 4 (3b) 5 (4-) 6 (4) w 23 34 22 11 3.47 15 12 16 70 5.76 1 7 17 78 5.67 m 2 cusp 5 0 1 w 79 11 0.12 110 4 0.04 100 1 0.01 m 2 carabelli’s trait 0 1 2 3 4 5 6 w 21 22 15 2 5 5 29 2.80 14 24 30 12 2 2 31 2.82 13 44 6 2 8 6 22 2.53 m1cusp number 3 4 5 6 7 w 0 38 51 9 1 4.73 3 40 59 8 3 4.72 5 27 54 15 1 4.80 m2 groove pattern 1 (+) 2 (x) 3 (y) w 64 2 31 1.66 42 5 60 2.17 23 7 68 2.46 m2 cusp number 1 2 3 w 1 95 3 2.02 0 87 26 2.23 1 68 26 2.26 m2 deflecting wrinkle 0 1 2 3 w 47 26 19 5 1.46 52 16 31 8 0.95 52 4 25 18 1.09 table 1., cont’d 50 trait expression cleveland memphis dallas n= 100 n= 117 n=101 m2 protostylid 0 1 2 3 6 w 90 0 5 4 1 0.28 90 20 2 2 0 0.26 59 35 3 3 0 0.50 m2 cusp 6 entoconulid 0 1 2 3 4 w 89 6 1 0 0 0.08 85 13 9 4 1 0.42 67 21 5 6 1 0.65 m2 cusp 7 metaconulid 0 1 2 3 4 5 w 39 15 30 15 1 0 1.24 36 7 45 19 4 1 1.56 51 4 20 17 7 1 1.28 m2 mesial trigonid crest 0 1 w 87 10 0.10 88 16 0.25 83 14 0.14 table 1., cont’d shows a slightly higher frequency for the pit expression while dallas has a higher cusp expression for carabelli’s trait. memphis also expresses the + groove pattern more often than dallas. dallas has a higher frequency of the y pattern. memphis shows a higher frequency for cusp 6 in comparison to dallas. dallas has a higher frequency for the mesial trigonid crest. conclusions the analyses of the three samples indicate that african american deciduous dentition usually has the more complex expression of a posterior trait or has a higher frequency of an anterior trait. in comparison to the european american sample, the african american samples have higher frequencies of: shovel shape trait mesial canine ridge hypocone development on maxillary molars carabelli’s pit or groove trait y posterior mandibular molar groove pattern deflecting wrinkle pit/groove trait for protostylid presence of cusps 6 and/or 7 however, the samples from memphis and dallas also have lower frequencies of tuberculum dentale and distal canine ridge traits, as well as the x and + posterior mandibular molar groove patterns in comparison to the cleveland sample. acknowledgements dr. b. holly broadbent at the bolton brush growth study, case western reserve university, cleveland, oh; dr. edward r. harris, the university of tennessee health sciences center, memphis, tn; dr. keith condon, freedman’s cemetery of dallas, tx; dr. qi jiang, youngstown state university, youngstown, oh. research was supported by the ohio state university graduate student alumni research award. 51 table 2. dichotomization based on weighted averages trait absence presence shovel shape 0, 1 2, 3 tuberculumdentale incisor 0 pits/grooves (1) canine ridge (2) maxillary canine mesial ridge 0 1+ maxillary canine distal ridge 0 1+ mandibularcanine distal ridge 0 1+ maxillary anterior molar hypocone 2 = 2, 3m1&3m2 = 3, 3h1&3h2 = 4, 4-and 4 = 5 maxillary posterior molar hypocone 3a = 3, 3b = 4, 4= 5, 4 = 6 maxillary posterior molar cusp 5 0 1+ carabelli’s trait absence (0), pit (1-3), cusp (4-6) cusp number of mandibular anterior molar 3 or 4 cusps = 1 5+ =2 groove pattern on the mandibular posterior molar + (1), x(2), y (3) deflecting wrinkle 0, 1 2, 3 protostylid absence (0), pit/groove (1-2), cusp (3-4) cusp 6 0 1+ cusp 7 0-2 3-5 mesial trigonid crest 0 1 52 cleveland memphis % % p<0.05 i 1 ss 32 34.4 i 2 ss 51 68.7 0.000 ucss 48 45 i1ss 4 4 i2ss 7 6 lcss 22 38 0.000 i 1 td 17 3 0.000 i 2 td 15 2.6 0.000 uctd 25 28.7 ucmr 1 2.6 ucdr 11 6 0.025 lcdr 1 4.3 table 3. results: cleveland and memphis samples — anterior dentition cleveland dallas % % p<0.05 i 1 ss 32 38 0.014 i 2 ss 51 46 0.025 ucss 48 37.3 0.001 i1ss 4 9.3 0.025 i2ss 7 21 0.000 lcss 22 37.6 0.000 i 1 td 17 6 0.001 i 2 td 15 2 0.000 uctd 25 12.7 0.000 ucmr 1 6.8 0.014 ucdr 11 1.9 0.002 lcdr 1 0 table 4. results: cleveland and dallas samples — anterior dentition cleveland dallas % % p<0.05 i 1 ss 32 38 0.014 i 2 ss 51 46 0.025 ucss 48 37.3 0.001 i1ss 4 9.3 0.025 i2ss 7 21 0.000 lcss 22 37.6 0.000 i 1 td 17 6 0.001 i 2 td 15 2 0.000 uctd 25 12.7 0.000 ucmr 1 6.8 0.014 ucdr 11 1.9 0.002 lcdr 1 0 table 5. results: memphis and dallas samples — anterior dentition 53 cleveland memphis % % p<0.0.5 um1 hypocone 2 61 13.9 0.000 3 22 19 4 12 49.6 0.000 5 5 17.3 0.000 um2 hypocone 3 25.5 13 0.000 4 37.7 10.6 0.000 5 24.4 13.8 0.001 6 12 60.9 0.000 cusp 5 12 3.5 0.004 carabelli’s trait absent 21 12 0.002 pit 39.4 57.9 0.000 cusp 39.4 30.7 0.004 cusp number of the mandibular anterior molar 1 38 38 2 61.6 68 0.014 groove pattern + 66 39 0.000 x 2 4.7 y 32 56 0.000 deflecting wrinkle 24.7 38.2 0.000 protostylid pit/ groove 5 19.2 0.000 cusp 5 1.7 cusp 6 1 24 0.000 cusp 7 16 21 0.025 mesial trigonid crest 10 5.4 0.025 table 6. results: cleveland and memphis samples — posterior dentition cleveland dallas % % p<0.0.5 um1 hypocone 2 61 2.9 0.000 3 22 18.6 4 12 58.8 0.000 5 5 19.6 0.000 um2 hypocone 3 25.5 0 0.000 4 37.7 6.8 0.000 5 24.4 16.5 0.008 6 12 75.7 0.000 cusp 5 12 1 0.001 carabelli’s trait absent 21 12.9 0.004 pit 39.4 51.5 0.000 cusp 39.4 35.6 cusp number of the mandibular anterior molar 1 38 31.4 0.008 2 61.6 69 0.008 groove pattern + 66 23.5 0.000 x 2 7 0.025 y 32 69.4 0.000 deflecting wrinkle 24.7 43.4 0.000 protostylid pit/ groove 5 38 0.000 cusp 5 3 cusp 6 1 33 0.000 cusp 7 16 25 0.002 mesial trigonid crest 10 14 table 7. results: cleveland and dallas sample — posterior dentition 54 memphis dallas % % p<0.0.5 um1 hypocone 2 13.9 2.9 0.001 3 19 18.6 4 49.6 58.8 0.002 5 17.3 19.6 um2 hypocone 3 13 0 0.000 4 10.6 6.8 5 13.8 16.5 6 60.9 75.7 0.000 cusp 5 3.5 1 carabelli’s trait absent 12 12.9 pit 57.9 51.5 0.014 cusp 30.7 35.6 0.025 cusp number of the mandibular anterior molar 1 38 31.4 0.008 2 68 69 groove pattern + 39 23.5 0.000 x 4.7 7 y 56 69.4 0.000 deflecting wrinkle 38.2 43.4 0.025 protostylid pit/ groove 19.2 38 0.000 cusp 1.7 3 cusp 6 24 33 0.002 cusp 7 21 25 mesial trigonid crest 5.4 14 0.002 table 8. results: memphis and dallas sample — posterior dentition 55 literature cited aguirre l, castillo d, solarte d, moreno f. 2006. frequency and variability of five non metric dental crown traits in the primary and permanent dentitions of a racially mixed popu lation from cali, colombia. dent anthropol 19: 39-48. bailey j. 1992. the long view of health. case western reserve university newsletter february. condon cg, becker jl, edgar hjh, davidson jm,kalima p, kysar d, moorhead s, owens vm, condon k. 1998. freedman’s cemetery site 41dl 316 dallas, texas: assessments of sex, age at death, stature, and date of interment for excavated burials. texas department of trans portation, environmental affairs division, ar chaeology studies program, report no. 9. edgar hjh. 2002. biological distance and the afri can american dentition. phd dissertation. de partment of anthropology, the ohio state uni versity. grine fe. 1986. anthropological aspects of the deciduous teeth of south african blacks. in: singer r, lundy jk, editors. variation, culture, and evolution in african population. johannes burg: witwatersrand university press. p 47-83. hanihara k. 1961. criteria for classification of crown characters of the human deciduous denti tion. j anthropol soc nippon 69:27-45. hanihara k. 1963. crown characters of the de ciduous dentition of the japanese-american hy brids. in: brothwell, dr. dental anthropology. new york: pergamon press. p 105-124. hanihara k. 1966. mongoloid dental complex in the deciduous dentition. j anthropol soc nip pon. 74:61-71. hanihara k. 1967. racial characteristics in the dentition. j dent res 46:923-926. hanihara k. 1976. statistical and comparative studies of the australian aborignial dentition. the university museum, the university of to kyo, bulletin no. 11. university of tokyo press. harris ef. 2001. deciduous tooth size distribution in recent humans: a world-wide survey. in: brook a, editor. dental morphology. 12th inter national symposium on dental morpholo gy. sheffield: academic press. p 13-30. jørgensen kd. 1956. the deciduous dentition: a descriptive and comparative anatomical study. acta odontol scand 14:1-202. lease lr, harris ef. 2001. absence of association between body size and deciduous tooth size in american black children. dent anthropol 15:7-11. lease lr. 2003. ancestral determination of afri can american and european american decidu ous dentition using metric and non-metric analysis. phd dissertation, department of an thropology. the ohio state university. sciulli pw. 1977. a descriptive and comparative study of the deciduous dentition of prehistoric ohio valley amerindians. am j phys anthropol 47:71-80. sciulli pw. 1990. deciduous dentition of a late archa ic population of ohio. hum biol 62:221-245. sciulli pw. 1998. evolution of dentition in prehis toric ohio valley native americans ii. mor phology of the deciduous dentition. am j phys anthropol 106:189-205. szlachetko kr. 1959. investigations on the mor phology of the human deciduous denti tion. anthropologia 3:247-279. 3 dental anthropology 2022 │ volume 35│ issue 01 a contextualized enamel growth rate and thickness data set collected from british populations spanning the past 2,000 years christopher aris 1,2 * 1 human osteology lab, skeletal biology research centre, school of anthropology and conservation, university of kent, canterbury, uk 2 department of applied science, wrexham glyndwr university, wrexham, uk the microscopic study of modern human permanent enamel has commonly analysed both enamel thickness (e.g., macho & berner, 1993; reid and dean, 2006; suwa & kono, 2005; smith et al., 2006a, 2006b; aris et al., 2020b) and daily secretion rates (dsrs; e.g., beynon et al., 1991a; lacruz & bromage, 2006; mahoney, 2008; aris et al., 2020a; 2020b; aris and street, 2021). both enamel thickness and dsrs have multiple component parts required for their reconstruction and analysis. for enamel thickness these include dentine area, enamel cap area, and enamel dentine junction length; and for dsrs include pre-averaged regional secretion rates collected across the enamel cap (e.g., aris et al., 2020b). the complexity of these features of human enamel has allowed their subsequent analysis to be broad, but to date these have been inconsistent in coverage in terms of tooth type and enamel feature. for example, permanent molars have been widely analysed for their thickness (e.g., schwartz, 2000; suwa and kono, 2005; smith et al., 2006a, 2006b; olejniczak, smith, feeney, machiarelli, mazurier, bondioli, and radovčić, 2008; mahoney, 2010; aris et al., 2020b) and cuspal dsrs (e.g., beynon et al., 1991a; lacruz and bromage, 2006; smith et al., 2007; mahoney, 2008; aris et al., 2020b). conversely the study of permanent incisors and canines has seen very limited research for dsrs (fitzgerald, 1998; reid, benyon, and ramirez rozzi., 1998; schwartz, reid, and dean, 2001; aris et al., 2020a; aris and street, 2021) or for thickness outside of 3d analyses (e.g., kono, suwa, and tanijiri, 2002; kono and suwa, 2008; smith et al., 2012; buti, lacabec, panetta, tripodi, salvadori, hublin, and benazzi, 2017). the study of lateral molar dsrs has been similarly limited (beynon et al., 1991a; lacruz and bromage, 2006; aris et al., 2020b). in addition to the disproportionate use of microscopic enamel features across tooth types, outside of a select few examples, large data sets for permaabstract this article represents an open repository of human enamel data collected/reconstructed from seven populations covering a 2,000 year time period in britain via five temporally distinct periods. in total, data were collected from 285 permanent teeth, including maxillary and mandibular first molars, and maxillary canines and first incisors. data were gathered through thin histological methods using standard procedures for sectioning human dental material. in regards to enamel growth, data is collected for daily secretion rates (dsrs) for the inner, mid, and outer areas of lateral and cuspal enamel. for enamel thickness average (aet) and relative (ret) enamel thickness, cuspal linear thickness (ct), and lateral linear thickness (lt) was collected. alongside the data presented, this article also provides clear and transparent explanations for all the methods involved in its production, in order to ensure understanding of the rigorous protocol and consistency associated with the data provided. the novel data is also contextualised with a compilation of equivalent data published in past articles. *correspondence to: christopher aris university of kent wrexham glyndwr university email: christopher.aris@glyndwr.ac.uk keywords: enamel thickness, daily secretion rates 4 dental anthropology 2022 │ volume 35│ issue 01 nent enamel features have not been presented or made openly accessible (e.g., reid and dean, 2006; smith et al., 2006a). furthermore, in the cases where developmental enamel variables are made available, outside of a few exceptions (e.g., kono et al., 2002; grine, 2004; reid and dean, 2006; mahoney, 2010; le luyer et al., 2014; buti et al., 2017), they are most frequently reported for single populations/samples. moreover, such variables are also typically reported as averages for groups. where individual-level enamel data has been reported, it has only concerned enamel thickness, and one single human sample (kono et al., 2002; skinner et al., 2015; lockey et al., 2020). these single human samples were also generated as a comparative sample for equivalent hominin/hominoid data analysis, rather than in direct analysis of human enamel growth/morphological patterns. there is therefore a clear need for the further generation of developmental enamel variable data from multiple modern human populations, in order for intra-specific research of human dentition to continue – a topic that has seen a resurgence in recent years (e.g., le luyer, rottier, and bayle, 2014; aris et al., 2020a, 2020b; aris and street 2021). since the pioneering of enamel thickness research involving human samples (e.g., molnar and gantt, 1977; martin, 1983, 1985), a great deal of research has involved 2d sections of teeth. an area where enamel research has developed over time, and also been less restrictive, is within 3d analysis of anterior teeth (e.g., feeney, zermeno, reid, nakashima, sano, bahar, and smith, 2010; smith et al., 2012; buti et al., 2017) and molars (e.g., konotakeuchi, suwa, kanazawa, and tanijiri, 1997; kono et al., 2002; smith et al., 2006a; kono and suwa, 2008). these 3d-based studies have involved inter-species hominin analyses, as well as also developing the methodological approaches for intraspecific human enamel thickness analysis. moreover, genetic analyses have also begun to emerge within the ongoing research of human enamel, which have made substantial strides to explaining inter-species enamel thickness differences within the human phylogeny (e.g., horvath et al., 2014, ungar and hlusko, 2016). while possessing a clear utility, these lines of research do not directly or fully address all the issues discussed so far. they do however help show the importance of continued and nuanced research of human enamel. this therefore highlights the utility of providing more open access to relevant enamel thickness data. alongside the areas of inequality in research coverage and data availability regarding microscopic features of human enamel, there is a growing trend in intraspecific analyses investigating whether enamel growth and thickness has varied within the human species over relatively short periods of time. to date, these analyses have found significant variations in both enamel thickness and regional dsrs between geographically similar populations differing in context by as little as 400 years (aris et al., 2020a; 2020b). this varies from older research in the field which frequently has either pooled dental samples for their growth and thickness data, or just used a single sample population, in order to create representative data sets for geographic regions or the entire human species (e.g., beynon et al., 1991b; lacruz and bromage, 2006; smith et al., 2007; mahoney, 2008). while not all past research has pooled human populations (e.g., grine, 2004; reid and dean, 2006), the prevalence towards doing so has meant that more recent research looking into whether the pooling of samples from different populations has been forced to create completely new histological sample collections to conduct their analyses. in these more recent analyses the use of comparative data sets from the pooled representative samples are limited in their utility (e.g., aris et al., 2020b). in addition, while the production of new samples is useful to the field of dental anthropology, its destructive nature should be considered and pre-existing material used where possible and appropriate to help preserve dental remains wherever possible (aris, 2020). this article aims to address the above issues by providing a large and freely accessible data set for researchers to use in analysis of both enamel thickness and enamel growth, via dsr measures across multiple tooth types and for multiple (five) modern human populations, further presented alongside a guide for pre-existing equivalent data. the novel data sets will compromise individual-level data for individuals, as well as regional-level enamel measurements. data of this type to date has not been reported or made available to this degree, with particular limitations existing regarding enamel growth data. the aim is that through this level of accessibility to this detailed a level of data, future research can more easily branch into the less well-covered features of enamel in current literature, and that further intraspecific research on modern humans can be conducted more easily. this will also represent the first data set regarding anterior tooth type enamel thickness accessible in this way. finally, it is hoped that the open access publication of this data will help expand the analy5 dental anthropology 2022 │ volume 35│ issue 01 sis of enamel data gathered at the microscopic level to institutions unable to directly support histological and/or micro-ct methods. material and methods dental sample to produce this repository, histological analysis was conducted on 285 permanent teeth collected from seven populations across five temporally distinct periods: roman (70-400ad), early premedieval (500-600ad), late pre-medieval (8001200ad), medieval (1000-1600), and modern-day clinical material (extracted within the last 20 years; table 1). all archaeological samples came from british excavations and modern-day samples compromised teeth extracted from england and southern scotland. sex was estimated where possible from skeletal elements of the archaeological individuals and known for a number of the modernday samples. details on known-sex/sex estimations are listed at the individual-level in the data sets, but a summary of the number of male and female individuals identified for each tooth type and population in provided in table 2. table 1. descriptive information of dental samples for each population and tooth type. population date location collection name number of teeth sampled upper incisors upper canines first molars all combined 70-~2000ad england and scotland n/a 81 69 115 roman 70-400ad cirencester, gloucester st james’ place/ bath gate 10 11 11 early premedieval 500-600ad ramsgate, kent ozengell 22 20 20 late premedieval 800-1200ad newcastle-upontyne, northumberland black gate 10 10 21 medieval 1100-1500ad canterbury, kent st gregory’s priory 19 8 43 1000-1600ad york, north yorkshire fishergate house 8 8 5 modernday extracted within the last 20 years newcastle-upontyne and glasgow ucl/kent 12 12 15 table 2. descriptive information regarding the number of individuals across populations and tooth types with known-sex/sex estimations. population number of male individuals number of female individuals upper incisors upper canines first molars upper incisors upper canines first molars known sex modern-day 5 9 4 7 3 5 estimated sex early pre-medieval 5 4 2 6 7 7 late pre-medieval 1 5 0 1 2 1 medieval 3 4 1 3 3 0 roman 2 5 6 3 4 1 6 dental anthropology 2022 │ volume 35│ issue 01 unworn teeth were selected where possible. when worn, only teeth with approximately 80% of their crown height remaining were selected based on criteria outlined by guatelli-steinberg and colleagues (2005), and when wear was present no data relating to the cuspal region of the enamel cap was collected (figure 1). one tooth was taken from each individual during the sampling process, following the guidelines for destructive sampling of human remains guideline outlined by mays and colleagues (2013) and on request from the institutions which curated the dental material utilised (see acknowledgements). left teeth were utilised wherever possible, with the right tooth only being used in instances where the left was missing, poorly preserved, or heavily damaged (data files note whether left or right were analysed). selection preference was also given to individuals presenting an antimere to the tooth being selected for sectioning. ancestry was unknown for all individuals across all populations from which samples were taken. in the case of the archaeological collections this was due to individual records not existing for any of the individuals of any of the populations studied. for the modern-day individuals, due to gdpr data laws (specifically those limiting the storage and dissemination of special data relating to an individual’s personal identity) the only information available was the biological sex and town/ city location from which the individual had the tooth sampled extracted. roman samples the roman samples were from two similarly located sites in cirencester: st james’ place and bath gate cemeteries (figure 2). both sites dated between 70-400ad (see table 1), presented archaeological material consistent with roman-british populations, and are thought to have been small urban populations with access to marine resources from the river severn (mcwhirr et al., 1982). early pre-medieval samples the early pre-medieval samples came from a site in thanet, ozengell grange (see figure 2), dated to 500-600ad (see table 1). the population is thought to have been small and coastal, with regular access to marine resources from the north sea and/or the english channel (millard et at al., 1969). the premedieval period in thanet is associated with newly developing urban areas following roman occupation (mckinley et al., 2015). figure 1. cross sections displaying examples of worn and unworn teeth analysed. the left cross section, a medieval upper first incisor, displays no occlusal wear. the right cross section, a roman upper first incisor, displays occlusal wear and thus no data requiring the cuspal region was collected from it. 7 dental anthropology 2022 │ volume 35│ issue 01 figure 2. map of the united-kingdom and northern ireland displaying the geographic location where the archaeological samples were excavated/modern-day samples were extracted. shapes denote the samples geographic origin, colour the time period they associated with (multi coloured shapes thereby meaning individuals from more than one time period originated from the same location): roman = blue, early pre-medieval = red, late pre-medieval = orange, medieval = purple, modern-day = green. similar guides to these populations’ context can be found in articles by aris and colleagues (2020a, 2020b). late pre-medieval samples the late pre-medieval sample came from the black gate cemetery site in newcastle-upon-tyne (see figure 2), dated to 800-1200ad (see table 1). this was a large urban population with access to marine resources through proximity to the river tyne (swales, 2012). medieval samples the medieval samples come from two sites: st gregory’s priory, canterbury, and fishergate house, york (see figure 2). the sites were dated between 1100-1500ad (hicks and hicks, 2001) and 1000-1600ad (holst, 2001) respectively (see table 1). both are documented to have been large urban populations (hicks and hicks, 2001; holst, 2001). modern-day samples the modern-day samples came from the ucl/ kent collection, a repository of teeth collected from dental surgeries in northern england (newcastleupon-tyne) and southern scotland (glasgow) (see figure 2). ethical approval for histology research on this collection of teeth was obtained from the united kingdom national health service research ethics committee (rec reference: 16/sc/0166; project id: 203541). sample preparation before any tooth was sectioned as a part of producing the data set, resin casts were produced for each incisor, canine and molar using standard methods (aris, 2020). producing casts in this way allows for 8 dental anthropology 2022 │ volume 35│ issue 01 the reproduction of the surface morphology of dental crown, thus allowing for future researchers to analyse features not within the data such, such as crown morphology, microwear, and enamel surface features including perikymata and linear enamel hypoplasia. thin sections were produced using standard histological procedures (e.g., mahoney, 2008; aris, 2020). all teeth were first embedded in an epoxy resin and hardener mixture (buehler®) in order to minimise the possibility of teeth fracturing during the sectioning process. embedded samples were then cut at low speeds using a diamond-edged wafering blade (buehler® isomet 1000 precision cutter) through the apex of crown cusps at a longitudinal angle. samples were then mounted on glass microscope slides and subsequently lapped using grinding pads (buehler®) until around 120µm thick. ground samples were then polished using 0.3µm aluminium oxide powder to remove any evidence of lapping. polished samples were then placed within an ultrasonic bath for a two-minute period in order to remove any micro-debris before being dehydrated using 90% and 100% ethanolbased solutions (fisher scientific®). dehydrated sections were finally cleared using histoclear® and mounted with a glass cover slip using a mounting medium (dpx®). all sections were examined using polarised light microscopy (olympus bx53 upright microscope). analysis and image capture was conducted using micro imaging software (cellsens). due to the requirements for cuts to be made precisely through the cusp and dentine horn apex in order for enamel growth and thickness data collected to be reliable (aris et al., 2020b), lines were marked on the tooth to help guide the initial cutting of the teeth for each tooth type (figure 3). whether this method was successful was assessed by observing the shape of the dentine horn of each cross section – a sharp point (with a v-shaped appearance; smith et al., 2006a) at the apex denotes and precise cut; a curved/rounded apex a misaligned oblique cut (reid and guatelli-steinberg, 2017). where oblique cuts were noted the associated sections were not used for data collection (figure 4). measurements taken daily secretion rates daily secretion rates were reconstructed using standard methods for the inner, mid, and outer regions of the lateral and cuspal enamel areas of each tooth (e.g., beynon et al., 1991a; mahoney, 2008; schwartz et al., 2001). regions were determined by dividing the length of the associated figure 3. diagram of how marks were made on upper first incisors, upper canines, and first molars (left to right respectively) before cutting to create a line through the cusp apex and dentine horn. the dashed red line displays the line created by the marks made at the blue crosses. note the lack of blue cross on the unaligned root apex of the upper canine. the teeth displayed all came from the fishergate house medieval collection 9 dental anthropology 2022 │ volume 35│ issue 01 enamel area into three equal parts along the length of enamel prisms. cuspal enamel regions were determined within the appositional enamel of each tooth, and dsrs were taken from the mesial cusps of molar teeth. lateral enamel regions were determined within the area of imbricational enamel equidistant between the dentine horn and the dental cervix. lateral dsrs were taken from the buccal -mesial cusps of molar teeth, and from the labial enamel of canine and incisor teeth. for each region an initial measurement was made for the length of five adjacent cross striations following the long axis of an appropriate enamel prism. this measurement was then divided by five to give a mean daily rate of secretion (µm/day). this process was repeated five times to give a grand mean and standard deviation for each region of each tooth. cross striation measurements were all taken at between 20x and 40x magnification. figure 5 illustrates how cuspal and lateral regions were split and how cross striations were counted along enamel prisms. enamel thickness for each tooth, four 2d measures of enamel thickness were calculated: cuspal thickness (ct), lateral thickness (lt), relative enamel thickness (ret), and average enamel thickness (aet). each was measured and calculated using a composite image produced by stitching together 20x magnified images using cellsens digital software. ret is a dimensionless index and free-scale derivative of the average enamel thickness (aet) which encompasses the entire 2d surface area of an enamel cross section. aet (mm) is calculated by dividing the surface area by the length of the edj (enamel dentine junction) (martin, 1983). ret is then calculated by dividing the associated aet by the square root of the dentine surface area of the surrounding edj and bi-cervical diameter (e.g., smith et al., 2006a; olenjniczak et al., 2008; figure 6). cuspal thickness was taken from the buccalmesial cups of the molars and primary cusp of the incisors and canines. lateral thickness was also figure 4. cross sections displaying aligned and misaligned cuts, both observed through the shape of the dentine horn (highlighted with dashed red lines). the left cross section, a medieval upper first incisor, displays an aligned cut with sharp pointed, v-shaped, dentine horn apex. the right cross section, a roman first molar, displays a misaligned cut with a rounded dentine horn. 10 dental anthropology 2022 │ volume 35│ issue 01 figure 5. diagrams of incisor (top left), canine (top right), and molar (bottom) cross sections with inner, mid, and outer regions for cuspal and lateral enamel regions isolated for dsr analysis. white squares show these enamel regions. the black square shows a 40x magnified superimposition of the mid lateral molar enamel. black arrows indicate individual cross striations. 11 dental anthropology 2022 │ volume 35│ issue 01 taken from the mesial cusps of the molars, and from the labial region of incisor and canine enamel. cuspal thickness (mm) was calculated by measuring the distance between the apex of the dentine horn and the cusp tip. lateral thickness (mm) was calculated by measuring the maximum length between the edj and the enamel surface along a line perpendicular to the edj. the location of this line determined within the area of the tooth between the dental cervix and the first retzius line to form in contact with the outer enamel surface (see dotted lines of figure 1). these two linear measurements have been presented in past studies under different abbreviations (beynon and wood, 1986; grine, 2005; hlusko et al., 2004; mahoney, 2010; schwartz, 2000a, 2000b). pre-existing data equivalent data to that which is provided in this article, regarding enamel secretion rates and thickness, has been routinely published in studies regarding human enamel. a large number of those articles were compiled with details as to the enamel variables analysed and context information of relevant human samples, in order to contextualise the novel data generated for this project. by compiling this data it is easier to identify where the novel data presented here fills temporal and/or geographical gaps in existing data, and thus where gaps also persist. where the same data has been utilised in multiple published works only one is detailed; preference was given to the original source where possible (table 3). note: articles using similar data which have been published to date but are not included are those which utilised the data sets provided in this article (aris et al., 2020a, 2020b; aris and street, 2021). conclusions data utility the combined data sets presented here represent the largest data repository of its kind in relation to developmental variables of human enamel in both archaeological and modern contexts. moreover, it holds particular value in being the only such data set available which lists individual-level data for enamel growth and thickness for multiple tooth types and multiple different populations. this will allow for future research to have wider accessibility to comparative data for both intraand inter species and population analyses of permanent enamel involving human samples. moreover, it is figure 6. cross-sectional images and reconstructions of 2d enamel thickness measures taken for molars (left) and canines and incisors (right). c. the enamel cap area and b. the dentine encompassed by the enamel and bi-cervical diameter (double-headed arrow). the area of c. was divided by the length of the edj (marked by dotted red line) to give the average enamel thickness (aet) in mm. the aet is divided by the square root of the area of b and multiplied by 100 to give the relative enamel thickness (ret) (e.g. martin, 1983), which is a dimensionless index. the dotted white lines (ct) illustrate the cuspal enamel thickness measurements (e.g. beynon and wood, 1986). the dashed white lines (lt) illustrate lateral enamel thickness measurements (e.g. grine and martin, 1988). similar guides to taking these measures can also be found in an article by aris and colleagues (2020b). 12 dental anthropology 2022 │ volume 35│ issue 01 table 3. existing published data for enamel dsrs and relevant thickness measures detailed with temporal and geographic contexts, tooth type information, and level at which data is available. source location time period tooth types n data collected data level presented at cuspal dsrs lateral dsrs dsr data beynon et al., 1991b unknown unknown molars 11-15 x x species lacruz and bromage, 2006 unknown unknown molars 10 x x species smith et al., 2007 various various first molars 21 x species smith et al., 2009 germany modern-day third molars 7 x species mahoney, 2008 england and scotland bronze-age first molars 13 x population schwartz et al., 2001 england and south africa modern-day canines 28 x x sex thickness data source location time period tooth types n ret ct lt data level presented at smith et al., 2006a and b* various middle stone age and modern-day molars 1-55 x population olejniczak et al., 2008* various and unknown various and unknown first molars 1-6 x species lockey, 2020 unknown unknown molars 9-10 x individual martin, 1983 unknown unknown molars 13 x species skinner et al., 2015 various unknown molars 8-15 x individual smith et al., 2009 germany modern-day third molars 8 x species smith et al., 2008 various various various 12-58 x species sorenti et al., 2019 madrid, spain 20th century molars 20-31 x sex kono, 2004* asia various molars 40-41 x x population grine, 1991 unknown unknown first molars 10 x x species grine, 2004 various modern-day second molars 1-23 x x population reid and dean, 2006 various various various 15-37 x population gantt and rafter, 1998 unknown unknown molars 3-23 x x species mahoney, 2010 england and scotland various molars 69 x x population suwa and kono, 2005* ohio, usa 800-1100ad first molars 31-37 x x population kono et al., 2002* asia unknown first molars 5 x x individual macho and berner, 1993 zwentendorf, austria 1100ad first molars 21 x population saunders et al., 2007 belleville, canada 1821-1874ad canines and premolars 72 x sex feeney et al., 2010* indonesia modern-day canines 7-21 x population buti et al., 2017* various medieval and clinical canines 1-13 x population *some or all data generated within a 3d context 13 dental anthropology 2022 │ volume 35│ issue 01 hoped that the compilation of similar data available in past research publications here will assist in researchers locating suitable comparative data regarding enamel growth and thickness data in addition to that provided here. for specific examples of the data’s utility, all articles which have utilised any data presented here compromise the work of aris (2020), aris and colleagues (2020a, 2020b), and aris and street (2021). throughout these articles, all content here including enamel dsrs, enamel thickness, and methodological approaches, are used in specific research projects. data ethics and acknowledgements data of the kind presented here is collected via destructive methods, which has a permanent impact on the collections analysed, and thereby their curating institutions. as a result, while this data is publicly available for use in future research, it is strongly recommended that such research acknowledge both the generosity and ethical stringency of the curators acknowledged in this article. moreover, further care must be taken when utilising the modern-day data from the ucl/kent collection. not only should the university of kent be acknowledged, but it should be detailed that the ethical approval for histological research on this collection of teeth was obtained from the united kingdom national health service research ethics committee. furthermore, the rec reference: 16/ sc/0166; project id: 203541, should also be noted (as it has been here in section 2.1.5). acknowledgements thanks go to the corinium museum, trust for thanet archaeology, and the universities of durham, kent, and sheffield for granting permission to sample the teeth sectioned as a part of developing this repository. thanks also go to the two anonymous reviewers and editor for their positive feedback and comments which helped greatly improve this article. references aris, c. (2020). the histological paradox: methodology and efficacy of dental sectioning. papers from the institute of archaeology, 29(1), 1-16. aris, c., mahoney, p., & deter, c. (2020a). enamel thickness and growth rates in modern human permanent first molars over a 2000 year period in britain. american journal of physical anthropology, 173(1), 141-157. aris, c., mahoney, p., o'hara, m. c., & deter, c. (2020b). enamel growth rates of anterior teeth in males and females from modern and ancient british populations. american journal of physical anthropology, 173(2), 236-249. aris, c., & street, e. (2021). growth rates of accessory human enamel: a histological case study of a modern-day incisor from northern england. dental anthropology journal, 34(1), 3-12. beynon, a. d., dean, m. c., & reid, d. j. (1991a). histological study on the chronology of the developing dentition in gorilla and orangutan. american journal of physical anthropology, 86(2), 189-203. beynon, a. d., dean, m. c., & reid, d. j. (1991b). on thick and thin enamel in hominoids. american journal of physical anthropology, 86(2), 295-309. beynon, a. d., & wood, b. a. (1986). variations in enamel thickness and structure in east african hominids. american journal of physical anthropology, 70(2), 177-193. buti, l., le cabec, a., panetta, d., tripodi, m., salvadori, p. a., hublin, j. j., & benazzi, s. (2017). 3d enamel thickness in neandertal and modern human permanent canines. journal of human evolution, 113, 162-172. feeney, r. n., zermeno, j. p., reid, d. j., nakashima, s., sano, h., bahar, a., & smith, t. m. (2010). enamel thickness in asian human canines and premolars. anthropological science, 118(3), 191-198. fitzgerald, c. m. (1998). do enamel microstructures have regular time dependency? conclusions from the literature and a large-scale study. journal of human evolution, 35(4-5), 371386. gantt, d. g., & rafter, j. a. (1998). evolutionary and functional significance of hominoid tooth enamel. connective tissue research, 39(1-3), 195206. grine, f. e. (1991). computed tomography and the measurement of enamel thickness in extant hominoids: implications for its palaeontological application. palaeontologica africana, 28(1), 61-69. grine, f. e. (2004). geographic variation in human tooth enamel thickness does not support neandertal involvement in the ancestry of modern europeans. south african journal of science, 100 (7), 389-394. grine, f. e. (2005). enamel thickness of deciduous and permanent molars in modern homo sapiens. american journal of physical anthropology, 126(1), 14-31. grine, f.e. and martin, l.b. (1988). enamel thickness and development in australopithecus and 14 dental anthropology 2022 │ volume 35│ issue 01 paranthropus. in: grine, f.e. (ed.), evolutionary history of the "robust" australopithecines (pp. 342). new york, aldine de gruyter. guatelli-steinberg, d., reid, d. j., bishop, t. a., & larsen, c. s. (2005). anterior tooth growth periods in neandertals were comparable to those of modern humans. proceedings of the national academy of sciences, 102(40), 14197-14202. hicks, m., & hicks, a. (2001). st gregory's priory, northgate, canterbury: excavations 19881991 (vol. 2). canterbury archaeological trust limited. hlusko, l. j., suwa, g., kono, r. t., & mahaney, m. c. (2004). genetics and the evolution of primate enamel thickness: a baboon model. american journal of physical anthropology, 124(3), 223-233. horvath, j. e., ramachandran, g. l., fedrigo, o., nielsen, w. j., babbitt, c. c., clair, e. m. s., & wall, c. e. (2014). genetic comparisons yield insight into the evolution of enamel thickness during human evolution. journal of human evolution, 73, 75-87. kono, r. t. (2004). molar enamel thickness and distribution patterns in extant great apes and humans: new insights based on a 3dimensional whole crown perspective. anthropological science, 112(2), 121-146. kono, r. t., & suwa, g. (2008). enamel distribution patterns of extant human and hominoid molars: occlusal versus lateral enamel thickness. bulletin of the national science museum, tokyo, series d, 34, 1-9. kono, r. t., suwa, g., & tanijiri, t. (2002). a threedimensional analysis of enamel distribution patterns in human permanent first molars. archives of oral biology, 47(12), 867-875. kono-takeuchi, r., suwa, g., kanazawa, e., & tanijiri, t. (1997). a new method of evaluating enamel thickness based on a three-dimensional measuring system. anthropological science, 105 (4), 217-229. lacruz, r. s., & bromage, t. g. (2006). appositional enamel growth in molars of south african fossil hominids. journal of anatomy, 209(1), 1320. le luyer, m., rottier, s., & bayle, p. (2014). brief communication: comparative patterns of enamel thickness topography and oblique molar wear in two early neolithic and medieval population samples. american journal of physical anthropology, 155(1), 162-172. lockey, a. l, alemseged z, hublin j. j, skinner m. m. (2020). maxillary molar enamel thickness of plio-pleistocene hominins. journal of human evolution, 142(1), 102731. macho, g. a., & berner, m. e. (1993). enamel thickness of human maxillary molars reconsidered. american journal of physical anthropology, 92(2), 189-200. mahoney, p. (2008). intraspecific variation in m1 enamel development in modern humans: implications for human evolution. journal of human evolution, 55(1), 131-147. mahoney, p. (2010). two-dimensional patterns of human enamel thickness on deciduous (dm1, dm2) and permanent first (m1) mandibular molars. archives of oral biology, 55(2), 115-126. martin, l. b. (1983). the relationships of the later miocene hominoidea (doctoral dissertation, university of london). martin, l.b., (1985). significance of enamel thickness in hominoid evolution. nature, 314, 260– 263. mays, s., elders, j., humphrey, l., white, w., & marshall, p. (2013). science and the dead: a guideline for the destructive sampling of archaeological human remains for scientific analysis. english heritage publishing with the advisory panel on the archaeology of burials in england. mckinley, j. i., leivers, m., schuster, j., & marshall, p. (2015). cliffs end farm isle of thanet, kent: a mortuary and ritual site of the bronze age, iron age and anglo-saxon period with evidence for long -distance maritime mobility. wessex archaeology. mcwhirr, a., viner, l., & wells, c. (1982). romano -british cemeteries at cirencester: cirencester excavations ii. cirencester excavation committee. cirencester. millard, l., jarman, s., & hawkes, s. c. (1969). anglo-saxon burials near the lord of the manor, ramsgate: new light on the site of ozengell? headley bros. molnar, s., & gantt, d. g. (1977). functional implications of primate enamel thickness. american journal of physical anthropology, 46(3), 447-454. olejniczak, a. j., smith, t. m., feeney, r. n., macchiarelli, r., mazurier, a., bondioli, l., & radovčić, j. (2008). dental tissue proportions and enamel thickness in neandertal and modern human molars. journal of human evolution, 55 (1), 12-23. reid, d. j., beynon, a. d., & ramirez rozzi, f. v. (1998). histological reconstruction of dental development in four individuals from a medieval site in picardie, france. journal of human evolution, 35(4-5), 463-477. 15 dental anthropology 2022 │ volume 35│ issue 01 reid, d. j., & dean, m. c. (2006). variation in modern human enamel formation times. journal of human evolution, 50(3), 329-346. reid, d. j., & guatelli‐steinberg, d. (2017). updating histological data on crown initiation and crown completion ages in southern africans. american journal of physical anthropology, 162(4), 817-829. saunders, s. r., chan, a. h., kahlon, b., kluge, h. f., & fitzgerald, c. m. (2007). sexual dimorphism of the dental tissues in human permanent mandibular canines and third premolars. american journal of physical anthropology, 133(1), 735-740. schwartz, g. t. (2000a). enamel thickness and the helicoidal wear plane in modern human mandibular molars. archives of oral biology, 45(5), 401-409. schwartz, g. t. (2000b). taxonomic and functional aspects of the patterning of enamel thickness distribution in extant large‐bodied hominoids. american journal of physical anthropology, 111(2), 221-244. schwartz, g. t., reid, d. j., & dean, c. (2001). developmental aspects of sexual dimorphism in hominoid canines. international journal of primatology, 22(5), 837-860. skinner m. m, alemseged z, gaunitz c, hublin j. j. (2015). enamel thickness trends in pliopleistocene hominin mandibular molars. journal of human evolution, 8(1), 35-45. smith, t. m., harvati, k., olejniczak, a. j., reid, d. j., hublin, j. j., & panagopoulou, e. (2009). brief communication: dental development and enamel thickness in the lakonis neanderthal molar. american journal of physical anthropology, 138(1), 112-118. smith, t. m., olejniczak, a. j., reh, s., reid, d. j., & hublin, j. j. (2008). brief communication: enamel thickness trends in the dental arcade of humans and chimpanzees. american journal of physical anthropology, 136(2), 237-241. smith, t. m., olejniczak, a. j., reid, d. j., ferrell, r. j., & hublin, j. j. (2006a). modern human molar enamel thickness and enamel–dentine junction shape. archives of oral biology, 51(11), 974-995 smith, t. m., olejniczak, a. j., tafforeau, p., reid, d. j., grine, f. e., & hublin, j. j. (2006b). molar crown thickness, volume, and development in south african middle stone age humans. south african journal of science, 102(11), 513-517. smith, t. m., olejniczak, a. j., zermeno, j. p., tafforeau, p., skinner, m. m., hoffmann, a., & hublin, j. j. (2012). variation in enamel thickness within the genus homo. journal of human evolution, 62(3), 395-411. smith, t. m., reid, d. j., dean, m. c., olejniczak, a. j., & martin, l. b. (2007). new perspectives on chimpanzee and human molar crown development. in s. e. bailey & j. j. hublin (eds.), dental perspectives on human evolution: state of the art research in dental paleoanthropology (pp.177-192). berlin: springer. sorenti, m., martinón‐torres, m., martín‐francés, l., & perea‐pérez, b. (2019). sexual dimorphism of dental tissues in modern human mandibular molars. american journal of physical anthropology, 169(2), 332-340. suwa, g., & kono, r. t. (2005). a micro-ct based study of linear enamel thickness in the mesial cusp section of human molars: reevaluation of methodology and assessment of within-tooth, serial, and individual variation. anthropological science, 113(3), 273-289. swales, d. l. m. (2012). life stress: a bio-cultural investigation into the later anglo-saxon population of the black gate cemetery (doctoral dissertation, university of sheffield). ungar, p. s., & hlusko, l. j. (2016). the evolutionary path of least resistance. science, 353(6294), 29-30. 36 dental anthropology 2021 │ volume 34│ issue 02 in a forensic context, successful positive identification of human skeletal remains starts by determining the biological profile of the individual: sex, age at death, ancestry, and stature. sex is usually one of the first parameters to be estimated, not only because other parameters and methods are sex dependent, but also because, when a reliable sex estimation can be obtained from the skeletal remains, only two possible outcomes are provided, male or female, thus lowering the number of possible individuals to whom the remains belong by approximately one-half (scheuer, 2002; scheuer and black, 2007). in skeletal elements, sex estimation is usually obtained by studying the pelvis followed by the skull, as it is considered to yield the second highest percentage of sexual dimorphism; nonetheless, it was found, that postcranial metric measurements can perform better than those from the skull, so these should be applied when the pelvis is unavailable (spradley & jantz, 2011). however, when both cranial and postcranial bones are absent or fragmented, other elements need to be considered (bruzek & murail, 2006; ubelaker, 2008; i̇şcan & odontometric patterns in human mandibular molars for sex estimation in a forensic context sofia f. franco 1* , álvaro azevedo 2,3 , vítor m. j. matos 4 , daniel mongiovi 1 , alexandra teixeira 1 1 iinfacts institute of research and advanced training in health sciences and technologies, department of sciences, university institute of health sciences (iucs), cespu, crl, gandra, portugal 2 faculty of dental medicine, university of porto, portugal 3 epiunit – institute of public health, university of porto, portugal 4 research centre for anthropology and health, department of life sciences, university of coimbra, coimbra, portugal abstract sex estimation is an important step in the identification of human skeletal remains, since it reduces the number of potential matches to approximately one-half. the os coxae and skull are considered the most dimorphic skeletal elements; however, when unavailable, teeth may be used alternatively. this study aims to evaluate the usefulness of specific odontometric parameters from the mandibular first molar – mesiolingual-distobuccal distance (mldb), mesiobuccal-distolingual distance (mbdl) and mesiodistal distance (md) on sex estimation in a portuguese sample composed of 135 mandibles (78 males; 57 females; ages atdeath ranging from 18 to 59 years old) selected amongst the 505 individuals of the coimbra identified skeletal collection (university of coimbra). since canines are considered the most accurate teeth for sexual assessment, comparison between first molar parameters and canines mesiodistal dimensions (md) was performed. statistical analysis showed sexual dimorphism in human first molars and cut-off points between male or female groups were determined. using the first molar mldb and mbdl, 60.7% and 65.2% of individuals were correctly classified, respectively. highest sex estimation accuracy was achieved with canine md, reaching 74.6%. our results indicate that although mandibular molar dimensions are useful for sex estimation, the canine should be prioritized when available to perform this task. *correspondence to: sofia f. franco institute of research and advanced training in health sciences and technologies, department of sciences university institute of health sciences gandra, portugal e-mail: sofiafranco16@gmail.com keywords: sexual dimorphism; odontometry; mandibular first molar; mandibular canine; forensic odontology 37 dental anthropology 2021 │ volume 34│ issue 02 steyn, 2013). in these circumstances, dentition can be a good alternative due to its hard, stable, and durable composition. teeth are often well preserved and can endure fire, decomposition, and severe trauma; furthermore, their analysis may contribute to the biological profile and its sexual dimorphism is represented by the differing teeth dimensions between males and females (tabor & schrader, 2010; cardoza, 2011; vishwakarma & guha, 2011). the most common tooth dimensions for sexual estimation are the mesiodistal (md) and buccolingual (bl) crown diameters, which are defined as the distance between the most mesial and most distal points of the crown, and the distance between the most buccal and most lingual points of the tooth, respectively (white & folkens, 2005; i̇şcan & steyn, 2013; kondo & manabe, 2016). although most studies apply these linear dimensions, other measures, such as the mandibular canine index (mci), have also been evaluated (scott & turner, 1988; rao et al., 1989). of the many studies performed worldwide, most identify the canine as the most sexually dimorphic tooth of the human dentition (acharya & mainali, 2007; acharya & mainali, 2008; cardoso, 2008; zorba et al., 2011; angadi et al., 2013; viciano et al., 2013; khamis et al., 2014). this is one of the reasons why the mci is so often applied. for example, rao and collaborators (1989) obtained an overall accuracy of 85.9% in sex estimation when using mci. nevertheless, since the degree of sexual dimorphism is population specific, some studies presented low success when employing this technique, which led to the focus being shifted to different teeth and dental dimensions (white & folkens, 2005; zorba et al. 2012; i̇şcan & steyn, 2013; narang et al., 2015). the posterior teeth, normally having more than one root, are considered by some researchers a better choice over anterior teeth since the former are more strongly attached to the dental arch and less prone to suffer postmortem loss, thus being more frequently found in fragmentary remains (i̇şcan & steyn, 2013; zorba et al., 2013; narang et al., 2015). on the other hand, the linear diameters are not as easily measured in molars as they are in anterior teeth. this fact, combined with the compromise of wear and attrition on the linear diameters, guided hillson and colleagues (2005) to come up with alternative dimensions for the posterior dentition. these included the crown diagonals: the distance between the most mesiolingual and most distobuccal points of the crown (mldb) and distance between the most mesiobuccal and most distolingual points (mbdl). the disarticulation of the mandible from the skull is a consequence of the decomposition of the human body and since the temporomandibular joint is one of the first to disarticulate during decay, it is not uncommon to find an isolated mandible in forensic contexts (pinheiro, 2006; cardoza, 2011; cunha, 2014). in portugal, there are very few studies on sexual dimorphism using teeth and none of them focus on the mesiodistal nor diagonal dimensions of the molars (cardoso, 2008; pereira et al., 2010; gonçalves et al., 2014; silva et al., 2016; gouveia et al. 2017; azevedo et al., 2019). therefore, the aim of this study was to evaluate the sexual dimorphism in mandibular first molars using the mesiodistal and alternative diagonal dimensions and to compare it to the mandibular canine with the traditional mesiodistal distance, in a sample from the portuguese population. materials and methods the sample was selected amongst the 505 individuals which compose the coimbra identified skeletal collection (20th century), housed at the department of life sciences, university of coimbra, according to the following selection criteria: portuguese nationality; age at death ranging between 18 and 59 years old; mandibles presenting at least one well preserved first molar showing minimal signs of attrition (occlusal wear). the resulting study base comprised 135 human mandibles, 78 (57.8%) belonging to males and 57 (42.2%) to females. the dimensions were taken in millimetres with a mitutoyo digimatic caliper, to the closest 0.01 mm. the following dimensions were measured on the left mandibular first molars: mesiodistal distance (md), mesiolingual to distobuccal distance (mldb), and mesiobuccal to distolingual distance (mbdl); when left teeth were absent, the antimere was used. additionally, md of right canines was taken for analysis and comparison with previous measures. all dimensions were measured according to the recommendations of hillson and collaborators (2005). the first molar was measured in 78 male and 57 female mandibles. only 59 out of the 135 mandibles had preserved canines (33 from males and 26 from females). all measurements were collected by an experienced observer, each taken in triplicate in non-consecutive order and separated in time, to avoid bias. the first value was eliminated, and the definitive value was obtained from the arithmetic average of the two last measurements. the intraobserver error was calculated with bland-altman analyses (myles & cui, 2007). the comparison be38 dental anthropology 2021 │ volume 34│ issue 02 tween sexes by the selected tooth sizes were performed by the independent sample t-test, after checking the normality assumptions by kolmogorov-smirnov or shapiro-wilk tests. receiver operating characteristics (roc) curves were applied to estimate the more accurate cut-off value for each dimension, which discriminate males from females. tooth measurements with a value under the cut-off point were considered to belong to female individuals, and values equal to or higher than the cut-off point to belong to male individuals. each dimension has an associated correct sexual classification accuracy, given by the sensitivity value for correctly classifying males and specificity for females. since mldb and mbdl were too correlated (multicollinearity), the joint performance of sex classification was assessed using a multivariate binary logistic regression with first molar md and canine md, by estimating the probability of an individual being a female. the regression model was constructed by enter-method approach. the omnibus test was used to check that the model holds an improvement with respect to the constant model. additionally, goodness of fit was assessed by hosmer-lemeshow statistical test, and the percentage of data variance explained by the model was quantified by r-square based statistics (cox & snell and nagelkerk). the predicted probabilities of being a female were then used as the classification variable. for the statistical analysis, version 25.0 of spss software (statistical package for social sciences) was used. the level of significance was established at 5%. a p-value with bonferroni correction for multiple comparisons (four dimensions) of <0.05 was considered to indicate statistical significance. results by the bland-altman analysis there were no relevant differences for the four dimensions (mldb, mbdl, molar md and canine md) between the second and the third measurements, which were not statistically significant (p>0.05). the maximum absolute mean difference between the second and the third measurements was 0.013mm registered in the molar md dimension. with 95% of confidence, the mean differences for all dimensions are lower than 0.03mm. moreover, the bland-altman analysis did not reveal a relationship between the differences obtained with the second and third measurements, and the magnitude of the measurements. it also revealed a non-dependence between the variation of those differences and the magnitude of the measurements. table 1 depicts the mldb, mbdl, first molar md and canine md dimensions. all measurements were higher for males, and the mean differences were statistically significant (p<0.05). in absolute terms, the larger differences (>0.41mm) were found in md dimensions. figure 1 shows the roc curves obtained for mldb and mbdl dimensions. the mbdl dimension exhibits a larger area under the curve (auc) than that of mldb, regardless of the cut-off considered. figure 2 shows the roc curves obtained for first molar md and canine md dimensions. this figure clearly illustrates that the auc were similar for almost cut-offs. table 2 presents the results of the auc analysis obtained for each of the four dimensions. interestingly, the auc values are well above 0.5 for all variables, showing statistical significance in any case (p<0.05). accordingly, as shown in figures 1 and 2, table 2 points out that the most discriminative variables are first molar md and canine md with an auc of 0.735 and 0.801, respectively. on the other hand, both mldb and mbdl dimensions have much lower performance in sex discrimination (auc values below 0.71). the accuracy assessment in sex prediction was based on the optimal cut-offs (table 3). using the mbdl dimension which presented higher auc than mldb for all cut-offs, with the optimal cut-off of 11.44mm, 67.9% of the males were correctly classified, whereas females were accurately identified dimensions (mm) female (n=57) male (n=78) p 95% ci (difference) lower-upper bond mldb 11.18±0.55 11.51±0.56 0.004 0.14-0.52 mbdl 11.29±0.52 11.70±0.52 <0.002 0.23-0.59 first molar md 10.77±0.57089 11.19±0.56530 0.04 0.10-0.69 canine md 6.39±0.35408 6.83±0.47072 <0.002 0.23-0.66 mean ±standard deviation; p represents the p-value with bonferroni correction for four dimensions. table 1. descriptive statistics for mldb, mbdl, first molar md, and canine md dimensions by sex. 39 dental anthropology 2021 │ volume 34│ issue 02 figure 1. roc curve analyses for the mldb and mbdl dimensions. the identity line represents the curve with auc equal to 0.5. figure 2. roc curve analyses for molar md and canine md dimensions. the identity line represents the curve with auc equal to 0.5. 40 dental anthropology 2021 │ volume 34│ issue 02 in 61.4% of the cases. the corresponding overall accuracy was around 65%. as expected, a greater accuracy in sex estimation was obtained with the optimal cut-offs for the first molar md and canine md dimensions, respectively, 10.89mm and 6.54mm. for both dimensions, 72.7% of the males were correctly classified. yet, the canine md presented better accuracy to identify the females with 76.9% accuracy, as opposed to 65.4% with the first molar md. the canine md showed an overall performance of approximately 75%, followed by the first molar md (overall accuracy around 70%). multivariate binary logistic regression was then performed to assess the joint impact of the two predictors (first molar md and canine md) in sex classification. the omnibus test of model coefficient (χ2=15.502; df=2) was statistically significant, with p<0.001. regarding the model goodness of fit, the result of the hosmer-lemeshow test indicates that the null hypothesis could not be rejected (χ2=11.812; df=8; p<0.16). the r square based statistics was found to be 31% (cox & snell statistics). finally, the first molar coefficient was not shown to be statistically significant (p=0.644), and the coefficient estimates for canine md (b=-2.606; standard error =0.988; wald = 6.957; df = 1; p=0.008) was found to be negative and statistically significant. so, when the first molar md and canine md were considered together, 69.2% of females and 69.7% of males were correctly classified, with the overall accuracy being 69.5%. discussion sexual assessment is one of the first steps in the process of the identity reconstruction. when skeletal preservation is seriously compromised by taphonomic and/or anthropic reasons, teeth are of great value for sex estimation due to their strength and durability (scheuer, 2002; bruzek & murail, 2006; scheuer and black, 2007; ubelaker, 2008; i̇şcan & steyn, 2013; scott et al., 2018). most studies estimating the sex from teeth size focus on the canines as these are known as the most sexually dimorphic teeth. in addition, it is dimensions auc ci95% auc p mldb (mm) 0.668 0.577-0.759 0.004 mbdl (mm) 0.705 0.617-0.792 <0.002 first molar md (mm) 0.735 0.603-0.866 0.008 canine md (mm) 0.801 0.684-0.918 <0.002 table 2. area under the curve (auc) and corresponding 95% confidence intervals (ci) for the mldb, mbdl, first molar md and canine md dimensions. p represents the p-value for the null hypothesis that the true auc is 0.5 with bonferroni correction for four dimensions. dimensions (optimal cut-off) accuracy female male total mldb (11.27mm) 30/57 (52.6%) 52/78 (66.7%) 82/135 (60.7%) mbdl (11.44mm) 35/57 (61.4%) 53/78 (67.9%) 88/135 (65.2%) first molar md (10.89mm) 17/26 (65.4%) 24/33 (72.7%) 41/59 (69.5%) canine md (6.54mm) first molar md+canine md* 20/26 (76.9%) 18/26 (69.2%) 24/33 (72.7%) 23/33 (69.7%) 44/59 (74.6%) 41/59 (69.5%) *multivariate binary logistic regression; the omnibus test of model coefficient (χ2=15.502; df=2; p<0.001) table 3. overall accuracy in sex classification for the mldb, mbdl, first molar md and canine md dimensions. 41 dental anthropology 2021 │ volume 34│ issue 02 considered the sturdiest and most durable tooth when faced with disease and trauma (kaushal et al., 2003; white & folkens, 2005), which explains why linear dimensions and other measures like crown indexes – such as the mci – are so commonly applied (rao et al., 1989; kaushal et al., 2004; zorba et al., 2011; khamis et al., 2014; azevedo et al., 2019). on the other hand, its increased probability of postmortem loss, compared to posterior teeth, due to its single root led researchers to start evaluating the sexual estimation accuracy in molars (i̇şcan & steyn, 2013; narang et al., 2015). this study corroborates the results of previous research showing that the dentition exhibits sexual dimorphism. statistically significant differences between males and females were found in mandibular first molars size. furthermore, the use of molar alternative dimensions to the mesiodistal and buccolingual parameters, such as the diagonal dimensions, can be particularly useful when the teeth crowns are partially absent. in this regard, the mbdl dimension provided the highest overall estimation accuracy: 65.2% of correct classifications and an auc of 70.5%. however, when considering all dimensions, canine md was the variable with the highest correct classification accuracy, namely 74.6% and an auc of 80.1%. both results are in accordance with the conclusions of studies from other populations, with diagonal dimensions having an accuracy range between 58.3% and 76.6% and mesiodistal dimensions a range between 63.9% and 85.8% (karaman, 2006; acharya & mainali, 2009; acharya et al., 2011; zorba et al., 2013; manchanda et al., 2015; narang et al., 2015; tabasum et al., 2017; azevedo et al., 2019). when both md variables were considered in a multivariate binary logistic regression, the accuracy of sexual estimation was 69.5%, slightly lower than the value achieved with canine md alone, and the first molar md variable ceased to be statistically significant in this situation, which reinforces the significance of the canine. nonetheless, these two dimensions were found to explain 31% of the existing variability between male and female individuals, which further corroborates that sexual dimorphism is present in the dentition. results from the first mandibular molar diagonal dimensions did not achieve a higher accuracy compared to the mesiodistal dimensions, leading to the conclusion that the canine should always be analysed when present. however, it is important to bear in mind that sample size was smaller when investigating the md dimensions, which could have led to a slight bias of results. in this sense, the molars prove to be a good option when combined with other elements and as a corroborating method. it is also important to mention that these results only apply to a portuguese population of the early 20th century since sexual dimorphism is population specific, as previously mentioned. because sexual dimorphism varies across space and time, further studies should test this method in a contemporaneous portuguese population (21st century) to enable the investigation of secular trends in these odontometric parameters in this specific population. conclusions the present results corroborate that the posterior dentition, namely odontometric parameters of the first mandibular molars, demonstrates sexual dimorphism in humans. the mesiodistal dimension of the canine was the variable that showed the highest sexual estimation accuracy, reaching levels of 74.6%. the diagonal dimensions of the molar, although less accurate, proved to be acceptable variables to be used in conjunction with other dimensions when the canine is unavailable, or when partial destruction of the molar crowns makes it impossible to use other parameters. additional research of these variables should be carried out in other populations, both to further validate the usefulness of posterior teeth in forensic scenarios and to contribute to secular trend investigations in the dentition’s sexual dimorphism. acknowledgments the authors would like to thank access to the coimbra identified skeletal collection provided by its curator (prof. sofia wasterlain) and the department of life sciences of the university of coimbra. thanks are also due to the research centre for anthropology and health, university of coimbra (financed by fundação para a ciência e tecnologia fct/mctes, project reference uidb/00283/2020). v.m.j.m was supported by the fct/mctes research project if001862014. references acharya, a.b., angadi, p.v., prabhu, a., & nagnur, s. (2011). validity of the mandibular canine index (mci) in sex prediction: reassessment in an indian sample. forensic science international, 204, 207.e1-207.e4. acharya, a.b., & mainali, s. (2007). univariate sex dimorphism in the nepalese dentition and the 42 dental anthropology 2021 │ volume 34│ issue 02 use of discriminant functions in gender assessment. forensic science international, 173(1), 47-56. acharya, a.b., & mainali, s. (2008). sex discrimination potential of buccolingual and mesiodistal tooth dimensions. journal of forensic sciences, 53 (4), 790-792. acharya, a.b., & mainali, s. (2009). limitations of the mandibular canine index in sex assessment. journal of forensic and legal medicine, 16(2), 6769. angadi, p.v., hemani, s., prabhu, s., & acharya, a.b. (2013). analyses of odontometric sexual dimorphism and sex assessment accuracy on a large sample. journal of forensic and legal medicine, 20(6), 673-677. azevedo, a., pereira, m.l., gouveia, s., tavares, j.n., & caldas, i.m. (2019). sex estimation using the mandibular canine index components. forensic science, medicine and pathology, 15(2), 191197. bruzek, j., & murail, p. (2006). methodology and reliability of sex determination from the sskeleton. in a. schmitt, e. cunha, & j. pinheiro (eds.), forensic anthropology and medicine – complementary sciences from recovery to cause of death (pp. 225-242). humana press, totowa, new jersey. cardoso, h.f.v. (2008). sample-specific (universal) metric approaches for determining the sex of immature skeletal remains using permanent tooth dimensions. journal of archaeological science, 35(1), 158-168. cardoza, a.r. (2001). forensic dentistry investigation protocols. in c. m. bowers (ed.), forensic dental evidence: an investigator’s handbook (2nd ed., pp. 73-92). elsevier academic press. cunha, e. (2014). a antropologia forense passo a passo. in a. gomes, enfermagem forense (volume 1, pp. 280-288). lidel, edições técnicas lda, lisboa. gonçalves, d., granja, r., cardoso, f.a., & carvalho, a.f. (2014). sample-specific sex estimation in archaeological contexts with commingled human remains: a case study from the middle neolithic cave of bom santo in portugal. journal of archaeological science, 49, 185 -191. gouveia, m.f., santos, i.o., santos, a.l., & gonçalves, d. (2017). sample-specific odontometric sex estimation: a method with potential application to burned remains. science and justice, 57 (4), 262-269. hillson, s., fitzgerald, c., & flinn, h. (2005). alternative dental measurements: proposals and relationships with other measurements. american journal of physical anthropology, 126(4), 413-426. i ̇şcan, m.y., & steyn, m. (2013). the human skeleton in forensic medicine (3rd ed). charles c thomas, publisher ltd, springfield. karaman, f. (2006) use of diagonal teeth measurements in predicting gender in a turkish population. journal of forensic sciences, 51(3), 630-635. kaushal, s., patnaik, v.v.g., & agnihotri, g. (2003). mandibular canines in sex determination. journal of the anatomical society of india, 52 (2), 119-124. kaushal, s., patnaik, v.v.g., sood, v., & agnihotri, g. (2004). sex determination in north indians using mandibular canine index. journal of indian academy of forensic medicine, 26(2), 45-49. khamis, m.f., taylor, j.a., malik, s.n., & townsend, g.c. (2014). odontometric sex variation in malaysians with application to sex prediction. forensic science international, 234, 183e1-183e7. kondo, s., & manabe, y. (2016). analytical methods and interpretation of variation in tooth morphology. journal of oral biosciences, 58(3), 85-94. manchanda, a.s., narang, r.s., kahlon, s.s., & singh, b. (2015). diagonal tooth measurements in sex assessment: a study on north indian population. journal of forensic dental sciences, 7 (2), 126. myles ps, cui j. using the bland-altman method to measure agreement with repeated measures. british journal of anaesthesia, 99(3), 309-311, 2007. narang, r.s., manchanda, a.s., & singh, b. (2015). sex assessment by molar odontometrics in north indian population. journal of forensic dental sciences, 7(1), 54-58. pereira, c., bernardo, m., pestana, d., santos, j.c., & mendonça, m.c. (2010). contribution of teeth in human forensic identification – discriminant function sexing odontometrical techniques in portuguese population. journal of forensic and legal medicine, 17(2), 105-110. pinheiro, j. (2006) decay process of a cadaver. in a. schmitt, e. cunha, j. pinheiro (eds.), forensic anthropology and medicine – complementary sciences from recovery to cause of death (pp. 85-116). humana press, totowa, new jersey. rao, n.g., rao, n.n., pai, m.l., & kotian, m.s. (1989). mandibular canine index – a clue for establishing sex identity. forensic science international, 42(3), 249-254. scheuer, l. (2002). application of osteology to forensic medicine. clinical anatomy: the official journal of the american association of clinical anatomists and the british association of clinical anatomists, 15(4), 297-312. scheuer, l., & black, s. (2007). osteology. in t. 43 dental anthropology 2021 │ volume 34│ issue 02 thompson, s. black (eds.), forensic human identification: an introduction (pp. 199-219). crc press, boca raton, florida. scott, g.r., & turner, c.g. (1988). dental anthropology. annual review of anthropology, 17(1), 99126. scott, g.r., turner ii, c.g., townsend, g.c., & martinón-torres, m. (2018). the anthropology of modern human teeth: dental morphology and its variation in recent and fossil homo sapiens (2nd ed). cambridge: cambridge university press. silva, a.m., pereira, m.l., gouveia, s., tavares, j.n., azevedo, á., & caldas, i.m. (2016). a new approach to sex estimation using the mandibular canine index. medicine, science and the law, 56(1), 7-12. spradley, m.k. & jantz, r.l. (2011). sex estimation in forensic anthropology: skull versus postcranial elements. journal of forensic sciences, 56(2), 289-296. tabasum, q., seharawat, j.s., talwar, m.k., & pathak, r.k. (2017). odontometric sex estimation from clinically extracted molar teeth in a north indian population sample. journal of forensic dental sciences, 9(3), 176. tabor, m.p., & schrader, b.a. (2010). forensic dental odentification. in d.r. senn, & p.g. stimson (eds.), forensic dentistry (2nd ed, pp. 163-185). crc press, boca raton, florida. ubelaker, d.h. (2008). forensic anthropology: methodology and diversity of applications. in m.a. katzenberg, & s.r. saunders (eds.), biological anthropology of the human skeleton (2nd ed, pp. 41-69). john wiley & sons, inc., hoboken, new jersey. viciano, j., lópez-lázaro, s., & alemán, i. (2013). sex estimation based on deciduous and permanent dentition in a contemporary spanish population. american journal of physical anthropology, 152(1), 31-43. vishwakarma, n., & guha, r. (2011). a study of sexual dimorphism in permanent mandibular canines and its implications in forensic investigations. nepal medical college journal, 13(2), 9699. white, t.d., & folkens, p.a. (2005). the human bone manual. san diego, california: elsevier academic press. zorba, e., moraitis, k., eliopoulos, c., & spiliopoulou, c. (2012). sex determination in modern greeks using diagonal measurements of molar teeth. forensic science international, 217, 19-26. zorba, e., moraitis, k., & manolis, s.k. sexual dimorphism in permanent teeth of modern greeks. forensic science international, 210, 74-81. zorba, e., spiliopoulou, c., & moraitis, k. (2013). evaluation of the accuracy of different molar teeth measurements in assessing sex. forensic science, medicine and pathology, 9(1), 13-23. 10 dental anthropology 2018 │ volume 31 │ issue 01 technical note: the definition of new dental morphological variants related to malocclusion marin a. pilloud 1,* 1 department of anthropology, university of nevada, reno, nv 89557 the arizona state university dental anthropology system (asudas) has been the standard in defining morphological variants of the teeth for over 25 years (turner et al., 1991). this publication outlines 36 traits of the dentition as well as rocker jaw, and mandibular and palatine tori. this original work is based on a rich literature defining morphological variation of the teeth (e.g., dahlberg ,1956; hanihara ,1961; harris and bailit, 1980; hrdlička ,1921; morris, 1970; morris et al., 1978; scott, 1977; scott, 1980; tomes, 1914; turner ,1970; turner, 1971). however, since its publication, there have only been a handful of additional traits defined, including the canine mesial ridge (irish and morris, 1996), maxillary premolar accessory ridges (burnett et al., 2010), deciduous morphological variants (sciulli, 1998), and molar crenulations (pilloud et al., 2017). there is room to expand our current understanding of dental morphological variation and to create definitions of additional traits. this paper broadens the current suite of traits and defines variants that may be of interest in bioarchaeological and forensic studies of dental variation that surround issues of malocclusion: canine/midline diastema, dental crowding, and maxillary and mandibular overjet. while these variants are not new to those working with teeth or the human skeleton (e.g., alt and türp, 1998; lasker, 1950), a working definition and scoring system has not yet been created within dental anthropology, with the exception of the midline diastema. each trait is discussed below and a definition and scoring system is provided. diastema while the midline diastema has been defined in the new volumes by scott and irish (2017) and edgar (2017), their definitions differ as to what exactly constitutes a diastema, they do not offer grades of expression, nor do they incorporate a canine diastema. the definition presented here is based on the definitions provided in these two works as well as several other preceding studies. further, the incorporation of a canine diastema is included. therefore, diastemata can occur in the maxillary midline or on either side of the mandibular or maxillary canine. the proposed scoring system incorporates both types of diastemata; however, they are discussed separately below. midline maxillary diastema midline maxillary diastemata have been reported on extensively in the clinical literature (e.g., chu et al., 2011; kamath and arun, 2016; shashua and årtun, 1999). anthropological research on midline maxillary diastemata has identified population, sex, and age differences in the occurrence of this trait (edgar, 2007; horowitz, 1970; lavelle, 1970; mcvay and latta, 1984; nainar and gnanasundaram, 1989; richardson et al., 1973). this discussion focuses on the adult dentition, as midline diastemata can commonly be found in primary and mixed dentition, and can be lost as the abstract since the codification of the arizona state university dental anthropology system over 25 years ago, few additional morphological traits have been defined. this work serves to expand the current suite of traits currently collected by biological anthropologists. these traits surround various issues of malocclusion and follow clinical definitions of these traits as well as incorporate observed population variation in character states. these traits include issues of spacing (i.e., diastema and crowding) as well as mandibular and maxillary occlusion (i.e., overbite, underbite). a discussion of the etiology and utility of these traits in bioarchaeological and forensic anthropological research is also given. *correspondence to: dr. marin a pilloud, department of anthropology, university of nevada, reno mpilloud@unr.edu keywords: dental crowding, midline diastema, canine diastema, overbite, underbite, overjet 11 dental anthropology 2018 │ volume 31 │ issue 01 permanent teeth erupt (gkantidis et al., 2008). there are many definitions of diastemata that incorporate various space sizes and grades of expression. in a joint publication by the world health organization (who) and the international dental federation (idf), a midline diastemata is defined as a space of more than 2.0 mm (bezroukov et al., 1979). in their new volume on dental morphology, scott and irish (2017) define the midline maxillary diastema as any space greater than 0.5 mm (following lavelle, 1970), and see no need to further define the trait beyond present or absent (based on irish, 1993). edgar (2017) also defines midline diastema; however, in her scoring system, 1.0 mm of space is required for presence. none of the current scoring systems allow for different grades of expression and only focus on presence/absence. however, in their study of nearly 6,000 radiographs, mcvay and latta (1984) found a statistically significant difference in midline diastema size between their sample groups of white, black, and “oriental” (sizes defined as <0.49, 0.5-1.49, >1.5 mm). a study of 759 american black and white children also found there to be size differences, with 19% of blacks and 10% of whites having a midline diastema over 2 mm (horowitz, 1970). differences in size of midline diastemata were also reported among a sample in south india (nainar and gnanasundaram, 1989). it may therefore be useful to separate out grades of expression in global studies of diastema. canine diastema canine diastemata can occur in the maxilla (sometimes referred to as premaxillary diastema) between the maxillary canine and the lateral incisor (schultz, 1948), or between the canine and third premolar (mongtagu, 1989). canine diastemata also occur on the mandibular canine, again on either side of the tooth. lavelle’s (1970) study of diastemata among 656 individuals found the majority of diastemata were between the maxillary third premolar and canine and the maxillary second incisor and canine. a study by keene (1963) evaluating midline and canine diastemata (>0.5 mm) among 183 white males found the most common diastema location was between the maxillary canine and the third premolar (even more common than midline diastema). keene also found that the majority of diastemata were between 1 and 3 mm in size. these studies highlight the potential role of canine diastemata in defining human population variation. definition and scoring system: diastema in this proposed system, a diastema is defined as any gap between the teeth with a separation of 0.5 mm or more. diastemata can be scored in three locations: 1) maxillary central incisors, 2) maxillary canines, and 3) mandibular canines (figure 1). among the canines, the separation can occur on either side, between the canine and the lateral incisor, or the canine and the third premolar. the current scoring system does not differentiate between the two locations. 0 – absent (< 0.50 mm) 1 – low-grade diastema 0.5-1.49 mm 2 – high-grade diastema ≥1.5 mm affected teeth: maxillary central incisors, mandibular canine, maxillary canine dental crowding and occlusion in this discussion, it is important to define occlusion and note the ideal model of occlusion to identify deviations from normal (i.e., malocclusions). occlusion “relates to the arrangement of maxillary and mandibular teeth and to the way in which teeth contact” (türp et al., 2008:446). an ideal form of occlusion occurs when the “skeletal bases of maxilla and mandible are of the correct size relative to each other and the teeth [are] in correct relationship in all three planes of space at rest” (hassan and rahimah, 2007:3). the three planes being anteroposterior, vertical, and transverse. therefore, malocclusion would be any deviation from this norm to include malpositioning of teeth within the dental arcade (i.e., displacement or rotation.), or a disassociation between the dental arches in any of the three planes of direction (proffit, 1986). while there are many references regarding the treatment of malocclusion in the clinical literature (angle, 1907; dahiya et al., 2017; singhal et al., 2015), there is little consensus on how it is quantified or fully defined (tang and wei., 1993). the earliest and still commonly used classification of malocclusion is that offered by angle (1899). in this work, three types of malocclusion are described, all in relation to the position of the upper and lower first molar. class i describes normal positions of the molars, and can be further subdivided into class i normal and class i malocclusion. class i malocclusion figure 1. individual with a midline maxillary diastema (score of 1), and a canine diastema (score of 1) (photo courtesy of g. richard scott). 12 dental anthropology 2018 │ volume 31 │ issue 01 includes crowding, spacing, and rotations of the anterior teeth, even though the molars may be in normal alignment (silva and kang, 2001). class ii is a retrusion of the jaw (i.e., overbite) in which the mandibular teeth occlude posterior to normal (i.e., lower first molar occludes posterior to the upper first molar). class iii is a protrusion of the lower jaw (i.e., underbite) in which the mandibular teeth occlude mesial to normal, typically by the length of one premolar, but may be a larger distance in severe cases. since 1899, various other methods have been proposed to quantify malocclusion (e.g., baume and maréchaux, 1974; björk et al., 1964; little, 1975). in the late 1960’s, research out of the university of toronto developed the orthodontic treatment priority index to quantify various types of malocclusion (grainger, 1967). in the late 1970’s, the world health organization (who) and the international dental federation (fédération dentaire internationale– fdi, now called the world dental federation) devised a simple method to record malocclusion. this system includes crowding and diastemata as “space conditions”. in this system, crowding is defined as present when > 2 mm of space deficiency is observed between the size of the dental arch and the anterior teeth (i.e., incisors, canine, and both premolars). deviations from normal occlusion in this system include maxillary and mandibular overjets, openbites, and midline shifts, among others (bezroukov et al., 1979). as malocclusion can include crowding and malposition of the jaws, the following definitions of malocclusion are offered, generally following the definitions of angle (1899) and those of the who/fdi (bezroukov et al., 1979). definition and scoring system: dental crowding dental crowding (angle’s type i – malocclusion) is defined as the presence of any tooth that deviates from ideal alignment through either rotation or displacement. the system proposed here is based on that described by van kirk and pennell (1959). rotation and displacement can be categorized into two types: major or minor. minor rotation is under 45o, where major rotation is defined as 45o or greater from ideal alignment. minor displacement is under 1.5 mm, and major displacement is 1.5 mm or greater from ideal alignment either labially or lingually (figure 2). in the original system outlined in van kirk and pennell (1959), each tooth is scored and scores are summed to assess the level of malocclusion. this system could be cumfigure 2. scoring of rotation and displacement as part of dental crowding for lateral teeth. based on van kirk and pennell (1959). 13 dental anthropology 2018 │ volume 31 │ issue 01 bersome in the work of the biological anthropologist and could be impossible when faced with teeth that may be missing anteor post-mortem. therefore, the system below is proposed for use in forensic anthropological or bioarchaeological settings. crowding is subdivided into incisal and (first and second incisors) and lateral (canine and premolars). the molars are not considered in this system. if all teeth in each class are not present, the level of crowding cannot be scored; allowing for some, but not a lot of missing teeth. if bilateral winging is observed and no other crowding is present in the incisal region, crowding should not be scored (i.e., leave the entry blank for crowding and score winging in its place to avoid redundant data). incisal (first and second incisor) 0 – absent – both teeth are in ideal alignment (no rotation and no displacement) 1 – slight – one or both teeth show slight deviations from ideal alignment (rotation between 1o and 44o and/or displacement between 0.1 and 1.4 mm) 2 – moderate – at least one tooth shows major malalignment (rotation ≥ 45o and/or displacement ≥ 1.5 mm), the other may be in ideal alignment or show slight deviation 3 – severe – both teeth show major malalignment (rotation ≥ 45o and/or displacement ≥ 1.5 mm) affected areas: mandibular and maxillary incisors lateral (canine and third and fourth premolar) 0 – absent – all three teeth are in ideal alignment (no rotation and no displacement) 1 – slight – one or all three teeth show slight deviations from ideal alignment (rotation between 1o and 44o and/or displacement between 0.1 and 1.4 mm) 2 – moderate – at least one tooth shows major malalignment (rotation ≥ 45o and/or displacement ≥ 1.5 mm), the others may be in ideal alignment or show slight deviation 3 – severe – all three teeth show major malalignment (rotation ≥ 45o and/or displacement ≥ 1.5 mm) affected areas: mandibular and maxillary canines and premolars to illustrate this scoring method, two worked examples are presented. in figure 3, there is a set of mandibular teeth that illustrate crowding and can be scored as follows: incisal right and left – 0 – there is no rotation or displacement of teeth on the right or left sides lateral left – 2 – the fourth premolar shows slight rotation (< 45o) but shows major displacement (≥ 1.5 mm) lateral right – 2 – the right canine shows minor rotation (< 45o) and the third premolar shows major displacement (≥1.5 mm) figure 4 illustrates a set of maxillary teeth with crowding that can be scored as follows: incisal right – 2 – the right second incisor shows major displacement (≥1.5 mm) and the central incisor shows minor rotation (< 45o) incisal left – 2 – the left second incisor shows major displacement (≥1.5 mm) and the central incisor shows minor rotation (<45o) lateral left and right – 0 – there is no rotation or displacement of teeth on either side figure 3. mandibular teeth that illustrate crowding (photo courtesy of g. richard scott and christy g. turner, ii). figure 4. maxillary teeth that illustrate crowding (photo courtesy of g. richard scott and christy g. turner, ii). 14 dental anthropology 2018 │ volume 31 │ issue 01 discussion diastema there may be a number of causes for a midline diastema, to include a large superior labial frenum, supernumerary teeth, missing teeth, peg teeth, digit sucking, abnormal arch size, muscular imbalances in the oral region (huang and creath, 1995), ossifying fibroma of the palate (kamath and arun, 2016), or even a tongue piercing (tabbaa et al., 2010). however, genetics may also play a role. a familial study on the maxillary midline diastema reported the heritability to be 0.32 ± 0.14 among a white sample and 0.04 ±0.16 in a black sample. the researchers concluded that among the white sample there was a stronger genetic basis for midline diastema and that the environment could be playing a larger role in trait expression among the black sample (gass et al., 2003). while this study reports low heritabilities, many studies have documented population differences in the expression of the trait (huang and creath, 1995; lavelle, 1970; mcvay and latta, 1984; scott and irish, 2017), which suggests the utility of the trait in bioarchaeology and forensic anthropology. further, as several studies have illustrated prevalence rates of canine diastemata in different populations (e.g., keene, 1963), this trait may have value in biological anthropological studies as well. malocclusion dental crowding and malocclusion are often discussed in relation to the adoption of agriculture and the introduction of soft foods as part of the masticatory-functional hypothesis (carlson and van gerven, 1977; corruccini, 1984; corruccini et al., 1983; larsen, 2015). in this discussion, malocclusion encompasses two distinct features: malalignment of the teeth (i.e., crowding) and malalignment of the jaws (i.e., overbite and underbite). while these are related conditions of occlusion, they may have separate etiologies. while overand under-bites have not been traditionally recorded in bioarchaeological or forensic anthropological research, their heritability is well documented in the clinical literature (chen, 2006; lee and goose, 1982; lundström, 1948; walker, 1951). there is, however, considerable debate in the clinical and anthropological literature as to the exact cause of dental crowding. mossey (1999) argues that while the phenotype is ultimately the result of the environment and genes working together, there is evidence to suggest a strong genetic component to various traits of malocclusion. while there is a documented increase in crowding over human evolution, it is generally the result of a disproportion of the dental arches and the size of the teeth (proffit, 1986), both of which are largely the result of genes. in fact, a study of tooth size of “north american caucasians” found that individuals with larger teeth also had more evidence of crowding (doris et al., 1981). further, work on amazonian populations by normando and colleagues (normando et al., 2013; normando et al., 2011) has argued for a strong genetic component to crowding and malocclusions; although, differing opinions exist (see mckeever, 2012). hughes and colleagues (2001) also documented high heritabilities of spacing (crowding and diastemata) among australian children. in a clinical setting, the role of external forces such as resting or chewing pressures (proffit, 1986), and various skeletal, soft tissue, dento-alveolar factors as well as habits (i.e., thumb or finger sucking) (mcdonald and ireland, 1998) have a documented influence on dental development and malocclusion. while many of these factors that lead to crowding (e.g., size of teeth, supernumerary teeth) may be under genetic control, it is difficult to point to one genetic cause for crowding. as such, many studies have highlighted the role of environment in dental crowding and are largely dismissive of a genetic contribution (harris and johnson, 1991; harris and smith, 1982; king et al., 1993). proffit (1986), on the other hand, combines both genetics and environment by arguing that slight crowding is likely related to genetic factors, whereas in cases of severe malocclusion, external factors play a larger role. while the etiology of dental crowding may not be clear, its occurrence may still be important to study in terms of understanding changes in stresses upon the masticatory system, dental reduction, and changes in diet in the evolutionary past of humans. until now there has not been a way to quantify or define this trait that could be applicable outside of a clinical setting. the system proposed herein to record dental crowding can be systematically recorded in archaeological and medicolegal settings to evaluate questions of anthropological interest. finally, these traits of malocclusion (crowding and maxillary and mandibular overjet) may have relevance as traits that are heritable and could have importance in biological distance analyses as well as studies in the estimation of ancestry within forensic anthropology. a recent study on dental morphological variation collected data on dental crowding among modern samples and found that dental crowding could successfully differentiate populations (maier, 2017). moreover, there has already been a substantial amount of work exploring population variation in terms of the three types of malocclusion as defined by angle: class i normal, class i malocclusion (anterior crowding), class ii malocclusion (maxillary overjet), and class iii malocclusion (mandibular overjet). table 1 outlines the various 15 dental anthropology 2018 │ volume 31 │ issue 01 table 1. population variance of malocclusion study ancestry n class i normal % class i malocclusion % class ii malocclusion % class iii malocclusion % (horowitz 1970) white 321 53.6 na 33.6 4.7 black 397 76.8 na 11.4 6.3 (garner and butt 1985) black american 445 27.0 44.0 16.0 8.7 kenyan 505 16.8 51.7 7.9 16.8 (onyeaso 2004)) nigerian 663 24.5 50.0 13.7 11.8 (altemus 1959) african american 3289 16.48 66.4 12.3 4.9 (lew et al. 1993) chinese 1050 58.8 52.7 21.5 12.6 white 1000 44.3 61.1 52.2 3.5 (silva and kang 2001) latino 507 6.5 62.9 21.5 9.1 studies that immediately highlight population differences in the various types of malocclusion, thereby illustrating their relevance to anthropological studies of population variation. orthodontic considerations modern orthodontia can impact observations of all of these traits. while braces may seem ubiquitous, they are a relatively new development. in the united states orthodontic work made a marked appearance in the 1950s as the “baby boom” created a larger sample of potential patients. however, the practice did not really take off until the 1970s when the number of qualified orthodontists nearly tripled from the decade before (asbell, 1990). according to the american association of orthodontists (2016), nearly 5,000,000 people were receiving orthodontic care in the united states in 2016, and they estimated that half of the u.s. population could benefit from orthodontic work. in studying traits of malocclusion and the possibility of orthodontic work, it is important to consider various factors that may limit access to treatment. multiple studies have documented economic and social barriers to receiving orthodontic treatment (germa et al., 2010; krey and hirsch, 2012), as well as ethnic differences in desires for orthodontic treatment (reichmuth et al., 2005). additionally, cultural practices and views on beauty can also interfere. for example, in a nigerian sample of 141 individuals, a study found that 48 (34%) had artificially created a midline diastema for the “enhancement of personal beauty and aesthetic” (umanah et al., 2015:226). while orthodontic work could erase many of these traits, there are various factors to consider when studying a set of remains such as socioeconomic or social status, ancestry, and antiquity of the remains (i.e., death prior to 1970 is less likely to have had orthodontic care). conclusions these traits of malocclusion all figure prominently in clinical discussions of occlusion and are broadly related to conditions that include spacing issues (i.e., diastema and crowding), and deviations from normal occlusion (i.e., maxillary and mandibular overjet). while the midline diastema has been embraced by the asudas and other dental morphologists, the other traits described herein have not. the reason for this finding is likely related to a lack of understanding of the etiology of these conditions; however, it is argued here that these traits show a degree of genetic heritability and could be relevant to studies of population variation. yet, the environmental component of these traits of occlusion cannot be ignored and may therefore serve as a means to quantify the degree of malocclusion over human evolution. it is hoped that this definition of a scoring system will generate further discussions of traits of malocclusion and that comparative population studies can be generated to further our understanding of population variation and human evolution. acknowledgments i thank g. richard scott for always being supportive and for helping me work through this scoring system. he is always there to talk teeth with me. 16 dental anthropology 2018 │ volume 31 │ issue 01 references alt k. w., and türp j. c. 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(1921). further studies of tooth morphology. amer j phys anthrop, 4, 141-176. 17 dental anthropology 2018 │ volume 31 │ issue 01 huang w. j., and creath c. j. (1995). the midline diastema: a review of its etiology and treatment. pediatr dent, 17(3), 171-179. hughes t., thomas c., richards l., and townsend g. (2001). a study of occlusal variation in the primary dentition of australian twins and singletons. arch oral biol, 46(9), 857-864. irish j. d. (1993). biological affinities of late pleistocene through modern africal aboriginal populations: the dental evidence [ph.d.]. tempe, az.: arizona state university. irish j. d., and morris d. h. (1996). canine mesial ridge (bushman canine) dental trait definition. amer j phys anthrop, 99, 357-359. kamath m., and arun a. (2016). midline diastema. international journal of orthodontic rehabilitation, 7 (3), 101-104. keene h. j. (1963). distribution of diastemas in the dentition of man. amer j phys anthrop, 21(4), 437441. king l., harris e. f., and tolley e. a. (1993). heritability of cephalometric and occlusal variables as assessed from siblings with overt malocclusions. am j orthod dentofacial orthop, 104(2), 121-131. krey k.-f., and hirsch c. (2012). frequency of orthodontic treatment in german children and adolescents: influence of age, gender, and socioeconomic status. eur j orthod, 34(2), 152-157. larsen c. s. (2015). bioarchaeology: interpreting behavior from the human skeleton. cambridge: cambridge university press. lasker g. w. (1950). genetic analysis of racial traits of the teeth. cold spring harbor symp quant biol: cold spring harbor laboratory press. p 191 -203. lavelle c. l. b. (1970). the distribution of diastemas in different human population samples. eur j oral sci, 78(1-4), 530-534. lee g., and goose d. (1982). heritability of dental occlusal variables in a family study in liverpool, uk. arch oral biol, 27(11), 987-989. lew k. k., foong w. c., and loh e. (1993). malocclussion prevalence in an ethnic chinese population. aust dent j, 38, 442-449. little r. m. (1975). irregularity index: a quantitative score of mandibular anterior alignment. am j orthod dentofacial orthop, 68(5), 554-563. lundström a. (1948). tooth size and occlusion in twins. basel: karger publishers. maier c. (2017). the combination of cranial morphoscopic and dental morphological methods to improve the forensic estimation of ancestry [phd dissertation]: university of nevada, reno. mcdonald f., and ireland a. j. (1998). diagnosis of the orthodontic patient. oxford: oxford university press. mckeever a. (2012). genetics versus environment in the aetiology of maloccclusion. br dent j, 212(11), 527-528. mcvay t. j., and latta g. h. (1984). incidence of the maxillary midline diastema in adults. the journal of prosthetic dentistry, 52(6), 809-811. mongtagu a. (1989). growing young. granby, massachusetts: bergin &garvey publishers, inc. morris d. h. (1970). on deflecting wrinkles and the drypoithecus pattern in human mandibular molars. amer j phys anthrop, 32, 97-104. morris d. h., hughes s. g., and dahlberg a. a. (1978). uto-aztecan premolar: the anthropology of a dental trait. in: bulter pm, and joysey ka, editors. development, function and evolution of teeth (pp. 69-79). london: academic press. mossey p. a. (1999). the heritability of malocclusion: part 2. the influence of genetics in malocclusion. br j orthod, 26(3), 195-203. nainar s. h., and gnanasundaram n. (1989). incidence and etiology of midline diastema in a population in south india (madras). the angle orthodontist, 59(4), 277-282. normando d., almeida m. a. o., and quintão c. c. a. (2013). dental crowding. the angle orthodontist, 83(1), 10-15. normando d., faber j., guerreiro j. f., and quintão c. c. a. (2011). dental occlusion in a split amazon indigenous population: genetics prevails over environment. plos one, 6(12), e28387. onyeaso c. o. (2004). prevalence of malocclusion among adolescents in ibadan, nigeria. am j orthod dentofacial orthop, 126(5), 604-607. orthodontists a. a. o. (2016). legislative priorities. http://wwwglaoorg/portals/0/%212016% 20congressional%20leave-behind%20%281%29pdf. pilloud m. a., maier c., and scott g. r. (2017). molar crenulation trait definition and population variation. american academy of forensic sciences. new orleans, la. proffit w. r. (1986). on the aetiology of malocclusion. br j orthod, 13(1), 1-11. reichmuth m., greene k. a., orsini m. g., cisneros g. j., king g. j., and kiyak h. a. (2005). occlusal perceptions of children seeking orthodontic treatment: impact of ethnicity and socioeconomic status. am j orthod dentofacial orthop, 128(5), 575 -582. richardson e. r., malhotra s. k., henry m., little r. g., and coleman h. t. (1973). biracial study of the maxillary midline diastema. the angle orthodontist, 43(4), 438-443. schultz a. h. (1948). the relation in size between premaxilla, diastema and canine. amer j phys anthrop, 6(2), 163-180. sciulli p. w. (1998). evolution of the dentition in prehistoric ohio valley native americans: ii. mor18 dental anthropology 2018 │ volume 31 │ issue 01 phology of the deciduous dentition. amer j phys anthrop, 106, 189-205. scott g. r. (1977). classification, sex dimorphism, association, and population variation of the canine distal accessory ridge. hum biol, 49 (3), 453-469. scott g. r. (1980). population variation of carabelli's trait. hum biol, 52, 63-78. scott g. r., and irish j. d. (2017). human crown and root morphology: the arizona state university dental anthropology system. cambridge: cambridge university press. shashua d., and årtun j. (1999). relapse after orthodontic correction of maxillary median diastema: a follow-up evaluation of consecutive cases. the angle orthodontist, 69(3), 257-263. silva r. g., and kang d. s. (2001). prevalence of malocclusion among latino adolescents. am j orthod dentofacial orthop, 119, 313-315. singhal p., namdev r., jindal a., bodh m., and dutta s. (2015). a multifaceted approach through two by four appliances for various malocclusions in mixed dentition. clinical dentistry (09743979), 9(4). tabbaa s., guigova i., and preston c. (2010). midline diastema caused by tongue piercing. j clin orthod, 44(7), 426-428. tang e. l. k., and wei s. h. y. (1993). recording and measuring malocclusion: a review of the literature. am j orthod dentofacial orthop, 103(4), 344351. tomes c. s. (1914). a manual of dental anatomy: human and comparative. philadelphia: p. blakiston's son. turner c. g. (1970). new classification of nonmetrical dental variation: cusps 6 and 7. american association for physical anthropologists. washington, d.c. turner c. g. (1971). three-rooted mandibular first permanent molars and the question of american indian origins. amer j phys anthrop, 34, 299-242. turner c. g., nichol c. r., and scott g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, and larsen cs, editors. advances in dental anthropology (pp. 13-31). new york: wileyliss. türp j., greene c., and strub j. (2008). dental occlusion: a critical reflection on past, present and future concepts. j oral rehabil, 35(6), 446-453. umanah a., omogbai a.-a., and osagbemiro b. (2015). prevalence of artificially created maxillary midline diastema and its complications in a selected nigerian population. afr health sci, 15 (1), 226-232. van kirk l. e., and pennell e. h. (1959). assessment of malocclusion in population groups. am j orthod, 45(10), 752-758. walker n. f. (1951). tooth size and occlusion in twins. amer j hum genet, 3(1), 77-77. agnihotri and sikri 2010.1 1 teeth exhibit the least cellular turnover of the body’s structure, and they are readily accessible for examination. tooth size standards based on odontometric investigations can be used in age and sex determination (black, 1902). the variations in tooth size are influenced by genetic and environmental factors. whenever it is possible to predict the sex, identification is simplified because then only missing persons of one sex need to be considered. in this sense identification of sex takes precedence over age (camps, 1976). various features like tooth morphology and crown size are characteristic for males and females (dayal et al., 1998). among sikhs, sub-castes have been grouped into several categories like jats, aroras, khatris, ramgarhias, majhabis, rajputs and namdharis. historically, jat sikhs are landowners, farmers, and warriors. traditionally, the jat sikhs have been endogamous at caste level and exogamous at the (gotra) sub-caste level (sidhu, 2003). these are divided into numerous clans like aulak, bains, bajwa, bal, bath, bhullar, chahal, dhaliwal, dhillon, dosanjh, gill, grewal, hundal, kang, randhawa, sahota, sidhu and virk. there are 31 million jats in south asia. the majority of the 11 million jat sikhs in india live in punjab, a state in northern india. the jat sikhs are believed to be the merged descendants of the original indo-aryans and a later addition of indo-scythian tribes (dhillon, 1994). the present study establishes the morphometric characterizations of the first maxillary molar in indian jat sikhs. the study has been conducted with a special emphasis on the impact of sex factor on the morphometry of the first maxillary molar. crowns of maxillary molars have four main cusps, namely the paracone, protocone, metacone and hypocone. each cusp has an independent growth pattern (kraus and jordan, 1965) and a different evolutionary background (osborn, 1907). the paracone is the first to appear both ontogenetically and phylogenetically and is regarded as the successor of the single cone of the reptilian haplodont dentition (patterson, 1956). the hypocone tends to develop latest in terms of ontogeny and phylogeny, and it differentiates from the lingual cingulum (kraus and jordan, 1965). odontometric characteristics of each molar crown are thought to represent a cumulative effect of individual cusp dimensions (kanazawa et al., 1985), so analysis based on measurement of cusp dimensions promises to be more meaningful biologically than conventional measurements of whole crowns. teeth that develop later in ontogeny are expected to display greater sexual dimorphism due to the increasing differences in sex hormone production between males and females (gingerich, 1974). in mandibular molars, sexual dimorphism values were shown to be greater in talonid dimensions than in the trigonid, suggesting that sexual dimorphism is larger in the later developed crown units (yamada, 1981). the present study focuses on the sexual dimorphism of cusp diameters in the first maxillary molar and tests the hypothesis that the later developed distal cusps should display greater dimorphism than earlier developing mesial cusps. crown and cusp dimensions of the maxillary first molar: a study of sexual dimorphism in indian jat sikhs gaurav agnihotri1 and vimal sikri2 1department of anatomy, government medical college, amritsar, punjab, india, and 2government dental college, amritsar, punjab, india abstract the human first maxillary molar provides clues about evolution and is functionally important. crowns of maxillary molars have four main cusps, each having an independent growth pattern and different evolutionary background. the study aims to quantify the morphometric criterion for the maxillary first molar giving a special emphasis to sexual dimorphism. measurements of the first maxillary molar were taken on 100 casts of jat sikh students (50 males, 50 females) studying in the local medical college in the age group of 17-21 years. the jat sikh community of punjab is endogamous at the caste level. unpaired t-tests were used to compare the samples for males and females. there is statistically significant sexual dimorphism (p < 0.01) for the maxillary first molar’s crown and cusp components in the jat sikhs. the sequence of dimorphism in cusp dimensions corresponds to the order of formation of the cusps. the percentage sexual dimorphism for the hypocone is high (right 7.2%, left 7.4%). dental anthropology 2010;21(1):1-6. correspondence to: gaurav agnihotri, lecturer, government medical college, amritsar, punjab, india. e-mail: anatomygaurav@rediffmail.com. 2 materials and methods selection criteria one hundred subjects (50 males, 50 females) in the age interval of 17-21 years were selected for the study because attrition is considered to be minimal in this age group. the study was conducted on the students enrolled in the government medical college, patiala, india, and the government medical college, amritsar, india. consent of the subjects was obtained, and the study casts were made with the help of resident doctors, senior residents, and senior technicians at the local government dental college. only those jat sikh students were selected whose upper and lower arches fulfilled the following inclusion criteria. • healthy state of gingiva and peridontium, • caries free teeth, • normal overjet and overbite, • absence of spacing in the anterior teeth, • normal molar and canine relationship, and • clearly distinguishable central pit of first maxillary molar. odontometry measurements were taken with a vernier caliper with a precision of 0.02 mm. the following parameters were measured and computed: (a) the mesiodistal and buccolingual crown diameters and cusp diameters (fig. 1); (b) the mesiodistal (fig. 2) and buccolingual (fig. 3) crown diameters and cusp diameters (fig. 4). each cusp diameter is defined as the diagonal distance from the central pit to the most prominent convexity on the crown outline corresponding to the relevant cusp, taken perpendicular to the axis of the tooth (kondo, 1985). three additional variables were calculated for each of these dimensions: the crown area provides a measure of overall crown size: crown area = md x bl where md is the mesiodistal width and bl is the buccolingual length. the cusp index quantifies cusp size relative to overall crown size: cusp index = cusp diameter md x bl 100 and, sexual dimorphism: sexual dimorphism = m f m 100 where m and f are the mean values in males and females. this formula is applicable for computing sexual dimorphism in mesiodistal width, buccolingual length, and crown area. statistical analysis descriptive statistics, including distribution parameters, were calculated using origin 6.1 software (origin lab corporation, usa, version 6.1052 for windows). unpaired t-tests were used to compare the dimensions measured for males and females, and a table of the t distribution was consulted. attainment of statistical significance was set at alpha = 0.01. results the results have been depicted in tables 1, 2, 3 and 4. the study quantifies the morphometric criterion for the maxillary first molars in jat sikhs. in general the morphometric parameters were found to be quantitatively higher for the left side. the study establishes the existence of statistically g. agnihotri and v. sikri pa ra co ne protocone h yp oc on e metacone mesiodistal b uc co li ng ua l di st al lingual fig. 1. illustration of the measurement of crown dimensions. fig. 2. illustration showing the measurement of maximum mesiodistal crown dimension. 3 parameter side sex mean sd t-test p-value1 mesiodistal width right males 11.33 0.078 -19.88 <0.01 females 10.88 0.142 left males 11.39 0.195 -13.53 <0.01 females 10.87 0.187 buccolingual length right males 12.53 0.078 -19.51 <0.01 females 11.98 0.192 left males 12.60 0.192 -18.26 <0.01 females 11.98 0.142 crown area right males 142.07 1.859 -24.83 <0.01 females 130.29 2.789 left males 143.54 4.617 -17.33 <0.01 females 130.25 2.849 paracone diameter right males 5.82 0.118 -8.73 <0.01 females 5.63 0.124 left males 5.84 0.138 -11.19 <0. 01 females 5.64 0.089 protocone diameter right males 5.88 0.119 -13.39 <0.01 females 5.59 0.108 left males 5.90 0.089 -16.83 <0.01 females 5.60 0.078 metacone diameter right males 5.68 0.117 -13.48 <0.01 females 5.39 0.088 left males 5.70 0.102 -16.39 <0.01 females 5.40 0.079 hypocone diameter right males 6.98 0.122 -21.19 <0.01 females 6.51 0.104 left males 7.00 0.102 -25.80 <0.01 females 6.52 0.092 paracone index right males 48.82 1.114 2.46 n.s. females 49.31 0.902 left males 48.74 0.982 3.72 n.s. females 49.43 0.862 protocone index right males 49.32 1.102 -1.77 n.s. females 48.96 0.901 left males 49.24 0.983 -0.91 n.s. females 49.08 0.853 metacone index right males 47.65 1.089 -2.17 n.s. females 47.23 0.882 left males 47.59 0.982 -1.46 n.s. females 47.32 0.845 hypocone index right males 58.45 1.104 -7.12 <0.01 females 57.14 0.908 left males 58.55 1.137 -6.46 <0.01 table 1. descriptive statistics and tests for sexual dimorphism between males and females first molar cusp dimensions 1statistical significance was set at p < 0.01; ns = not significant (p > 0.01). significant sexual dimorphism (p < 0.01) for the maxillary first molars in jat sikhs. from table 1, it is evident that the parameters as measured for males and females when compared are found to be statistically significant. further in males or females individually, i.e. within the same sex (tables 2 and 3) when these parameters as measured, are compared, they are found to be statistically insignificant. from these findings, it can be inferred that there exists a definite statistically significant sexual dimorphism for the maxillary first molar in indian jat sikhs (p < 0.01). the percentage sexual dimorphism calculated came out to be higher for the buccolingual dimension (4.6% for 4 discussion dental morphological characteristics are useful for providing information for phylogenic and genetic studies and understanding variation within and among species. the crown characteristics are known to differ among racial groups; for example, australian aborigines have larger teeth, indians have smaller teeth, while whites have teeth intermediate in size (tedeschi, 1977). the jat sikhs are an endogamous group at caste level. they have distinct customs, traditions and food habits. as such the present study defines the criteria of the first molar tooth size for the jat sikhs. in general the morphometric parameters were found to be quantitatively higher for the left side. this observation holds true also for all the maxillary anterior teeth in north indians (agnihotri and jain, 2008) but not in south indians (nair et al., 1999). the crown dimensions for the first molar are comparable to those of the jats (kaul and prakash, 1984) in haryana. the jats of haryana constitute an agriculture-based community in north india. it is a combination of environmental factors and inheritance that controls the mesiodistal and buccolingual dimensions. the dimensions obtained for the male teeth are definitely on the higher side as compared to those for females. this can be explained on the basis of the shape of the first molar tooth, which is controlled by the genetic constitution of the individual. thus, the male teeth are usually larger in size as compared to the female teeth. it is the y chromosome that seems to contribute most in the size of teeth by controlling the thickness of dentine, whereas the x chromosome seems to be responsible for modulating thickness of the enamel. the sexual dimorphism in tooth morphology is attributable to the presence of relatively more dentine in the crowns of male teeth (iscan and kedici, 2003). the present study indicates that there exists a definite statistically significant sexual dimorphism for the maxillary first molar in indian jat sikhs (p < 0.01). this is in concordance with the work done on taiwan chinese (kondo, 1998) and on jordanian subjects (hattab et al., 1996). while dental difference between the sexes in several human groups has been found highly dimorphic, it was not found so in turks (iscan and kedici, 2003), where the lack of dimorphism comes from male subjects. this validates the perception that sexual dimorphism is population specific. the percentage sexual dimorphism calculated came out to be higher for the buccolingual dimension (4.6% for the right side and 5.18% for the left side) as compared to the mesiodistal dimension. this is consonant with the findings for american white (garn et al., 1966) and south indian (nair et al., 1999) subjects. since size dimorphism was consistently greater for the buccolingual tooth diameter, its more extensive use is indicated in like-sex and unlike-sex sibling and parent-child comparisons for tooth size. among the various crown dimensions, crown g. agnihotri and v. sikri fig. 3. illustration showing the measurement of maximum buccolingual crown dimension. fig. 4. depiction of the method of measuring cusp diameters. clockwise from the upper left are the paracone, protocone, metacone, and hypocone. the right side and 5.2% for the left side) as compared to the mesiodistal dimension. among the various crown dimensions, crown area displays the maximum dimorphism (9.0% for right side and 10.2% for left side). the maximum cusp size in decreasing order came out to be hypocone > protocone > paracone > metacone for these indian jat sikhs. the sex dimorphism in the cusp dimensions corresponds to the order of cusp formation, namely, hypocone > metacone > protocone > paracone. the percentage sexual dimorphism for the hypocone (right 7.2%; left 7.4%) is quite high in present study as compared to the other cusps. the cusp index exhibited the sequence: hypocone index > protocone index > paracone index > metacone index. the cusp indices (except for the hypocone index) did not exhibit statistically significant sexual dimorphism. 5 parameter side mean sd side mean sd t-test p-value mesiodistal width left 11.39 0.195 right 11.33 0.078 1.96 >0.01 buccolingual length left 12.60 0.192 right 12.53 0.078 2.13 >0.01 crown area left 143.54 4.617 right 142.07 1.859 2.01 >0.01 paracone diameter left 5.84 0.138 right 5.82 0.118 0.91 >0.01 protocone diameter left 5.90 0.089 right 5.88 0.119 0.92 >0.01 metacone diameter left 5.70 0.102 right 5.68 0.117 -0.90 >0.01 hypocone diameter left 7.00 0.102 right 6.98 0.122 0.96 >0.01 paracone index left 48.74 0.982 right 48.82 1.114 -0.35 >0.01 protocone index left 49.24 0.983 right 49.32 1.102 -0.36 >0.01 metacone index left 47.59 0.982 right 47.65 1.089 -0.32 >0.01 hypocone index left 58.55 1.137 right 58.45 1.104 -0.48 >0.01 parameter side mean sd side mean sd t-test p-value mesiodistal width left 10.87 0.187 right 10.88 0.142 -0.13 >0.01 buccolingual length left 11.98 0.142 right 11.97 0.192 0.13 >0.01 crown area left 130.25 2.849 right 130.29 2.789 -0.08 >0.01 paracone diameter left 5.64 0.089 right 5.63 0.124 0.69 >0.01 protocone diameter left 5.60 0.078 right 5.59 0.108 0.68 >0.01 metacone diameter left 5.40 0.079 right 5.39 0.088 0.57 >0.01 hypocone diameter left 6.52 0.092 right 6.51 0.104 0.59 >0.01 paracone index left 49.43 0.862 right 49.31 0.902 0.64 >0.01 protocone index left 49.08 0.853 right 48.96 0.901 0.65 >0.01 metacone index left 47.32 0.845 right 47.23 0.882 0.55 >0.01 hypocone index left 57.03 0.989 right 57.14 0.908 0.55 >0.01 table 2. descriptive statistics and tests for left-right side differences in males table 3. descriptive statistics and tests for left-right side differences in females area displayed the maximum dimorphism (9.0% for right side; 10.2% for left side). the present pioneer study on the maxillary molar tooth in indian jat sikhs provides data useful for anthropological, genetic, odontologic, and forensic investigations. this is particularly so since tooth morphology is known to be influenced by cultural, environmental, and racial factors (agnihotri and gulati, 2008). the maximum cusp size in decreasing order came out to be hypocone > protocone > paracone > metacone. this order has been found to differ among populations. for the japanese, kondo et al. (2005) found the sequence to be: protocone > hypocone > paracone. for american whites, biggerstaff (1976) reported the order to be protocone> metacone > paracone > hypocone. the sexual dimorphism in the cusp dimensions corresponds to the order of cusp formation, namely hypocone > metacone > protocone > paracone. thus, the ontogenetic hypothesis, that later forming structures show greater sexual dimorphism than earlier forming structures, can apparently be extended to dental crown components. the hypocone is considered to be the key innovation in mammalian evolution (hunter and jernvall, 1995). mammals that developed the hypocone became preadapted for masticating fibrous plants and subsequently demonstrated a markedly increased species diversity. the percentage sexual dimorphism for the hypocone (right 7.2%; left 7.4%) is high in present study as compared to the other cusps. this value is in fact comparable to the values for canine in north indian population (right 7.3%; left 8.1%). the canine is known to exhibit the largest sexual dimorphism in the human dentition. the cusp index exhibited the sequence: hypocone index > protocone index > paracone index > metacone index. however in the present study the cusp indices except the hypocone index did not demonstrate a statistically significant sexual dimorphism. though the cusp index sequence follows the same pattern in the japanese (kondo et al., 2005), the hypocone index in them is statistically significant. this can be attributed to differences in ethnicity. the hypocone index and hypocone diameter are the most dimorphic parameters for the jat sikh population. conclusion the study quantifies the morphometric criterion and first molar cusp dimensions 6 establishes the existence of a statistically significant sexual dimorphism (p < 0.01) for the maxillary first molars in jat sikhs. this study suggests that the hypocone index and hypocone diameter are the most dimorphic parameters for the jat sikh population. acknowledgements the authors would like to thank dr. satish agnihotri, colonel (retd) and dr. vikram agnihotri (capt) for their invaluable suggestions and encouragement. we also appreciate our statistician mrs. shaweta agnihotri, lecturer, bbk dav college, amritsar for her efforts and hard work. we are indebted to the resident doctors, senior residents, and senior technicians working in the local government dental college for their wholehearted support for the timely completion of the study. literature cited agnihotri g, gulati ms. 2008. maxillary molar and premolar indices in north indians: a dimorphic study. the internet journal of biological anthropology [vol 2, no 1] available from: http://www.ispub.com/ostia/ index.php. agnihotri g, jain rl. 2008. maxillary anterior teeth morphometry in north indians: a dimorphic study. nepal dent j 9:23-28. biggerstaff rh. 1976. cusp size, sexual dimorphism, and the heritability of maxillary molar cusp size in twins. j dent res 55:189-195. black 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forensic med toxicol 16:10-13. osborn hf. 1907. trituberculy in relation to the human molar teeth and primates. in: gregory wk, editor. evolution of mammalian molar teeth to and from the triangular type. new york: macmillan, p 48-65. patterson b. 1956. early cretaceous mammals and the evolution of mammalian molar teeth. fieldiana geol 1956;23:1-105. sidhu is, kaur k, sarhadi vk, joshi ds, mukhopadhaya r, mahajan sk, bhanwer ajs. 2003. study of genetic polymorphism at d21s11 and d21s215 loci in the jat sikh population of punjab. int j hum genet 3:45–50. tedeschi cg. 1977. examination of human remains. in: tedeschi cg, eckert wg, tedeschi lg, editors. forensic medicine. philadelphia: wb saunders company. yamada h. 1981. sexual dimorphism of molar crown size in a japanese population. jpn j oral biol 34:531-540. g. agnihotri and v. sikri table 4. sexual dimorphism for the crown and cusp dimensions parameter right side left side mesiodistal width 4.14% 4.78% buccolingual length 4.68% 5.18% crown area 9.04% 10.20% paracone 3.37% 3.55% protocone 5.19% 5.36% metacone 5.38% 5.56% hypocone 7.22% 7.36% prevedorou et al. 2010.2 42 the muslim conquest of the iberian peninsula in the early middle ages constitutes an important part in the history of spain, known from historical sources yet archaeologically unexplored. excavations at plaza del castillo in the city of pamplona in northern spain (fig. 1) recovered a large islamic cemetery dating to the eighth century a.d. the identification of intentional dental modification in the cemetery, a practice virtually absent in medieval spain but common in african groups, may suggest an african origin for part of the burial sample, a hypothesis also supported by the historically documented arrival of berbers from north africa during the time of muslim occupation. hence, the reconstruction of the geographic origins of the individuals interred at plaza del castillo will afford unique insight about the islamic occupation of the city of pamplona, as well as about the diffusion of muslim groups in iberian peninsula during the eighth century a.d. here we report the results of the preliminary study on migration in early medieval pamplona using biogeochemical analysis. in the last decade, the use of biogeochemistry to address past residential mobility and migration has provided an invaluable new line residential mobility and dental decoration in early medieval spain: results from the eighth century site of plaza del castillo, pamplona eleanna prevedorou1, marta díaz-zorita bonilla2, alejandro romero3, jane e. buikstra1, m. paz de miguel ibáñez4, kelly j. knudson1 1center for bioarchaeological research, school of human evolution and social change, arizona state university, tempe, az 85287-2402 2department of archaeology, durham university, united kingdom 3department of biotechnology, university of alicante, spain 4department of prehistory, university of alicante, spain correspondence to: eleanna prevedorou, center for bioarchaeological research, school of human evolution and social change, arizona state university, po box 87402, tempe az 85287-2402 email: eprevedo@asu.edu abstract excavations at plaza del castillo in pamplona (northern spain) revealed a large islamic necropolis dating to the eighth century a.d., including the skeleton of an adult female showing intentional dental modification (pla-159). while the practice of dental decoration was virtually absent in medieval spain, it is common in africa and suggests that this individual was born in africa and brought to spain later in life. the historically documented occupation of pamplona by muslim groups from northern africa between ca. 715 and 799 a.d. also supports an african origin. as an additional line of evidence, we investigated the geographic origins of two individuals from the cemetery, including pla-159, via radiogenic strontium and stable oxygen isotope analyses on enamel hydroxyapatite. the human isotopic signatures were measured following established methodologies and compared to the local geochemical composition and modern precipitation values. the data analysis showed a non-local isotopic signature for both individuals, suggesting that they moved to pamplona following childhood, probably from northern africa, during the islamization of the city. stable carbon isotope analysis revealed a diet heavily based on c 3 terrestrial plants. overall, this preliminary data set exemplifies the use of biogeochemistry as an analytical tool, and provides unique insight about the diffusion of muslim groups into the early medieval iberian peninsula. dental anthropology 2010;23(2):42-52. of evidence and a growing field in archaeological science. the methodology, introduced to archaeology from environmental and ecological studies, has been successfully applied to numerous studies in a variety of historic and prehistoric contexts with a wide geographic range. mobility and migration via isotopic analysis have been examined, for example, in the american southwest (e.g., ezzo et al., 1997; ezzo and price, 2002; price et al., 1994), mesoamerica (e.g., price et al., 2006; white et al., 2004), south central andes (e.g., knudson and buikstra, 2007; knudson and price, 2007; knudson and torres-rouff, 2009), south africa (cox and sealy, 1997), and thailand (e.g., bentley et al., 2007). in europe, isotopic studies of geographic origins have been conducted in england (e.g., montgomery et al., 2005), central europe (e.g., bentley et al., 2004; bentley and knipper, 2005; price et al., 1998; 2001), 43 iceland (e.g., price and gestsdóttir, 2006), the alps (e.g., müller et al., 2003), spain (díaz-zorita bonilla et al., 2009; prevedorou et al., 2009), and greece (e.g., nafplioti, 2008; richards et al., 2008). in this paper, we use biogeochemistry to test hypotheses explicitly formed by the bioarchaeological and historical evidence. we begin by presenting the site of plaza del castillo, along with the history of the region. we provide an analytical description of the typology, technique, and origin of the case of dental decoration observed in the islamic cemetery, and we present our research objectives. we continue by introducing biogeochemistry as an analytical tool to address human behavior, and we then describe the materials and laboratory methodology for this study. finally, we present our results and discuss the interpretation of this preliminary data set, as well as future research. archaeological and historical background: the site of plaza del castillo the cemetery of plaza del castillo, located in the city of pamplona, came to light in 2002 during the construction of an underground parking lot (fig. 2a). the large islamic necropolis, maqbara in arabic, was located outside the city walls covering an area of 4000 m2; however, the total area of the cemetery is not yet known. of the 160 undisturbed burials recovered in total, 50% were juveniles, while the adult burials consisted of approximately equal numbers of male and female individuals. following the islamic funerary traditions, the burials were single inhumations that lacked grave goods; bodies were placed in a simple pit lying on their right sides, with head towards southsoutheast facing the holy city of mecca (casal, 2003; faro carballa et al., 2007; de miguel ibáñez, 2007) (fig. 2a,b). the date of the islamic cemetery corresponds with the emergence of the islamic control in the iberian peninsula in eighth century a.d. and constitutes the first definite archaeological evidence for the muslim occupation of the city of pamplona. according to historic sources, pamplona came under islamic authority around 715 a.d. with the arrival of muslim groups, mostly berbers, from north africa (maghreb). the city remained under muslim control until 799 when the ruler mutarrif ibn musa was assassinated (faro carballa et al., 2007-2008). radiocarbon dating conducted thus far in one of the skeletons from plaza del castillo (burial 32) yielded a date between 660 and 770 cal. a.d. (beta-218654). hence, the onset of the muslim authority in pamplona in 715, and the radiocarbon date of burial 32 suggest that at least part of the plaza del castillo cemetery was in use during the initial islamization and the ensuing expansion of the muslim community in the city. the discovery of the maqbara is of great significance for the reconstruction of the historical trajectory of pamplona and northern spain in general. despite the belief that the conquest of the city took place with a pact between the conquerors and those conquered, it appears that the islamic occupation went through several crises that necessitated military intervention. arabic sources report that during uqba’s rule (probably in 734 a.d.), he had to suppress his opponents and take over their cities and that he was the one who conquered the city of arbona, subjugated galicia and pamplona, and brought in muslim people (al-marrakusi, 1999). thus, the individuals buried at plaza del castillo could in fact represent the muslims first arriving in pamplona, coming to suppress the continuous revolutions of the time in the name of emir. dental decoration in plaza del castillo skeletal analysis of the human remains from the islamic necropolis has identified the presence of intentional dental modification in the anterior dentition of burial 159 (pla159), an adult female (fig. 2b) (romero et al., 2009). the modified teeth were classified following the typology established by romero molina (1986), which constitutes the most complete classification system based on earlier revisions (saville, 1913; romero molina, 1958; rubín de la borbolla, 1940). scanning electron microscopy (sem) was performed on casts and replicas of the teeth to examine in detail the modified surfaces. silicon coltène® president plus jet and epoxy transparent resin araldite 2020® were used for the dental casts and replicas respectively, following established methodologies (galbany et al., 2006; romero and de juan, 2003). the dental replicas were analyzed with a sem hitachi s3000n at a magnification of 30x (servicios técnicos investigación, universidad de alicante). fig. 1. map of iberian peninsula showing the location of pamplona with observed radiogenic strontium isotope signatures in bedrock and soil. residential mobility and dental decoration 44 individual pla-159 showed dental modifications in 5 out of the 27 preserved teeth. missing teeth included agenesis of the mandibular right third molar; the maxillary left first and second incisors and canine were lost postmortem. modifications were identified on the mesial and distal surfaces of the maxillary right first incisor; the mesial and distal surfaces of the maxillary right second incisor; the mesial surface of the maxillary right canine; the mesial surface of the manbibular left first incisor; and the mesial surface of the mandibular right second incisor (fig. 3a,b). the mandibular right first incisor was not intentionally modified and thus it was used for biochemical analysis. the pattern of dental modification in individual pla159 matches the general types of b and c (following romero molina, 1986). according to anthropological and ethnographical literature on mesoamerica and africa, dental modification was preferentially performed on the six maxillary anterior teeth (goose, 1963; romero molina, 1958). however, modification of the mandibular dentition is also reported (e.g., this study; fastlicht, 1976; lagunas and karam, 2003; romero molina, 1958). intentional modification primarily of the maxillary incisors and canines, with extraction of the mandibular anterior teeth has been documented in various modern and ancient fig. 2. view of the islamic cemetery of plaza del castillo in pamplona during excavation, showing the uniformly oriented burials (a) and individual pla-159 in situ (b) (photo courtesy of gabinete trama de arqueología, pamplona) [color figure can be viewed in the electronic (pdf) version of the journal.]. e. prevedorou et al. 45residential mobility and dental decoration african groups (lagunas and karam, 2003; muwazi et al., 2005; pindborg, 1969; van rippen, 1918). typological analyses places the dental modifications of pla-159 among the ones reported for african groups (haour and pearson, 2005; tiesler, 2002). primarily in western, central, and southern africa, intentional dental modification of the anterior teeth in some cases consists of filing one or both interproximal sides, thereby destroying the incisal axis (finucane et al., 2008; gould et al., 1984; jones, 1992; reichart et al., 2007). this is similar to the modifications observed in african individuals resettled in the americas during the period of colonization (tiesler, 2002; price et al., 2006) and in iberian peninsula during 13th to 15th centuries a.d. (gonzalo et al., 2001). among the types closest to the modifications observed in plaza del castillo are the ones reported for western africa regions such as the niger (haour and pearson, 2005:431), wherein the shape of the tooth was modified without affecting the occlusal surface. however, no parallel types have yet been found for the removal of the enamel up to the cervical area as observed in individual pla-159 (fig. 3b). documentation of the practice of dental decoration in the iberian peninsula is scarce. dental modifications have been observed as part of post-mortem ritual in prehistoric spain (campillo et al., 2001). one case of an adult male of a possible sub-saharan origin with intentional dental modification is documented from a more recent islamic cemetery (13th to 15th centuries a.d.) in spain (gonzalo et al., 2001). a number of examples of dental modification are reported in portugal in later periods, associated with the trade of slaves, mostly unpublished. thus, the occurrence, as well as the typology of intentional dental modification at plaza del castillo suggest an african origin for pla-159 and argue for the presence of first-generation immigrants in the cemetery. research objectives the presence of the islamic cemetery in pamplona coincides with the conquest of the city by muslim groups in eighth century a.d. in particular, the identification of fig. 3. macroscopic and microscopic (sem) views of the dental modifications present in individual pla-159 in maxillary (a) and mandibular dentition (b) (photo by a. romero). abbreviations are: upper right first incisor (uri1); upper left second incisor (uli2); upper right canine (ucr); lower right second incisor (lri2); lower left first incisor (lli1). [color figure can be viewed in the electronic (pdf) version of the journal.] 46 the adult female pla-159 showing dental decoration in plaza del castillo raises significant questions regarding the geographic origins of the individuals buried in the maqbara. while the practice of dental modification was generally absent in early medieval spain, it is commonly documented in african groups suggesting that pla-159 was not part of the indigenous population. the historically documented episodic arrival of muslim groups, mostly berbers, from north africa (maghreb) in the iberian peninsula during the eighth century a.d. also supports an african origin for the individuals buried in plaza del castillo. nevertheless, during the muslim occupation part of the local population did convert to islam, and interaction between the two religious groups is suggested by the recovery of rings with arabic inscriptions in kufic script in two contemporaneous christian cemeteries in pamplona (faro carballa et al., 2007-2008). hence, the question raised by the bioarchaeological evidence is whether the individuals buried in the maqbara were born in pamplona or alternatively in africa, brought in spain later in life as part of the first generation of the incoming muslim groups during the islamization of the city. specifically, determining the youthful residence of pla-159 reveals important information regarding the nature of dental modification and its presence in medieval spain. to test the hypothesis of a non-local geographic origin and to begin exploring the residential histories of the individuals buried in plaza del castillo radiogenic strontium and stable oxygen isotope analyses were performed in a preliminary data set: the female pla159 showing dental decoration, and the adult pla-28 of indeterminate sex without evidence of dental decoration. in addition, stable carbon isotope analysis was conducted to reconstruct paleodiet. human behavior through biogeochemistry: general principles radiogenic strontium isotope analysis strontium is an alkaline earth element, and occurs naturally in four isotopes, the radiogenic 87sr (7.04%) and the stable isotopes 84sr (~0.56%), 86sr (~9.87%) and 88sr (~82.53%) (bentley, 2006). given that the radiogenic 87sr is formed over time by the radioactive decay of 87rb (rubidium), strontium isotope ratios in a geological region are a function of the geochemical composition and the age of rocks (bentley, 2006). the abundances of 87sr are normalized to the non-radiogenic 86sr and are reported as the 87sr/86sr ratio in order to allow for comparison among different samples (bentley, 2006); the 87sr/86sr ratio in different geological terrains ranges roughly between 0.700 and 0.750 (price et al., 2002). strontium moves from bedrock into the food chain via soil and groundwater. it ultimately is incorporated into the human skeleton by substituting for calcium in the crystalline lattice of hydroxyapatite of skeletal tissues due to the similar chemical structure of the two elements (bentley, 2006; ezzo, 1994; price et al., 2002). contrary to strontium elemental concentrations which vary according to trophic level, radiogenic strontium isotope ratios are not substantially fractionated by biological processes. the radiogenic strontium isotopic composition of human bone and teeth therefore reflect the isotopic composition of the individual’s diet and water sources, which in turn reflect the bioavailable strontium of the geological region and habitat from which the food and water sources were obtained (price et al., 2002). specifically, dental enamel reflects the composition of the strontium sources consumed during infancy and childhood because it forms during this period and does not remodel. in consequence, differences between the isotopic signature of tooth enamel and the isotopic signature of the region in which the individual died can reveal changes in the residence history of the individual, as long as local food and water sources were consumed (price et al., 2002). however, due to the vast variability of geological formations, different locations can have similar geochemical signatures; therefore, possible mobility between geochemically similar regions will not be expressed in the skeletal elements (burton et al., 2003). stable oxygen isotope analysis oxygen occurs in three stable isotopes, 16o (99.765%), 18o (0.1995%) and 17o (0.0355%), and it is the most abundant chemical element in the earth’s oceans and the second most abundant in the atmosphere (kendall and caldwell, 1998). oxygen isotope data (δ18o c(v-pdb) ) are reported relative to the v-pdb (vienna peedee belemnite) carbonate standard and are expressed in per mil (‰) using the following standard formula: δ18o = (((18o/16o sample )/(18o/16o standard )) – 1) × 1,000 (coplen, 1994; craig, 1961). oxygen is incorporated into the minerals of the human skeleton mainly via the ingestion of water (δ18o w ) (luz and kolodny, 1985). due to the isotopic equilibrium between ingested water and bioapatite when the body temperature is constant, hydroxyapatite carbonate and phosphate will reflect meteoric water values (balasse and ambrose, 2002; longinelli, 1984). oxygen isotope signatures in water sources vary according to a number of environmental factors, including altitude, latitude, distance from the coast, precipitation, temperature and humidity (e.g., craig, 1961; kohn, 1996; kohn et al., 1996; luz and kolodny, 1985; sponheimer and lee-thorp, 1999). thus, given that local water sources were used, oxygen isotope values from hydroxyapatite will reflect the isotopic composition of the local environment during tooth and bone formation. several studies have shown that the correlation of the δ18o c with meteoric water makes it useful for assessing residence and mobility across different environmental zones (land et al., 1980; kohn and law, 2006). however, a number of factors, including utilization of a variety of drinking water sources, storage and preparation of drinking water, as well as enrichment in 18o due to breastfeeding, can affect human δ18o values (knudson, 2009). e. prevedorou et al. 47 stable carbon isotope analysis carbon occurs in two stable isotopes, 12c representing 99% of the element, and 13c representing the remainder 1% (smith, 1972). carbon isotope ratios (δ13c c(v-pdb) ) are reported relative to the v-pdb (vienna peedee belemnite) carbonate standard and are expressed in per mil (‰) using the following standard formula: δ13c = (((13c/12c sample )/ (13c/12c standard )) 1) × 1000 (coplen, 1994). during the process of photosynthesis, plant tissues incorporate 12c preferentially relative to 13c, such that the atmospheric 13c/12c ratio is greater than the one in plant tissues; a process termed fractionation. plants are categorized relative to the different photosynthetic pathways that they use to fix atmospheric co 2 : briefly, plants as maize, millet, and other tropical grasses use the c 4 (or hatch-slack) pathway, whereas most plants, including grass, woody shrubs and trees, use the c 3 (or calvin) pathway (smith and epstein, 1971). in general, c 4 plants demonstrate less negative δ13c values with an average of -12.5‰, contrary to c 3 plants that exhibit more negative δ13c values with an average of -26.5‰ (smith, 1972; smith and epstein, 1971; vogel, 1978). furthermore, the carbon isotopic composition of the diet is represented in the consumer’s tissue; thus animals that consume c 3 plants will have more negative δ13c values than ones that consume c 4 plants (e.g., ambrose et al., 1997; ambrose and norr, 1993; van der merwe and vogel, 1978). finally, carbon isotopic values from bone collagen reflect the dietary protein, whereas carbon isotopic values from bone carbonate represent the isotopic composition of the whole diet; in humans, δ13c values from apatite reflect an average of the whole diet offset by 9.4‰ (ambrose and norr, 1993). materials and laboratory methodology our sampling strategy was designed to provide isotopic data from tooth enamel that formed early in an individual’s life. the maxillary left first incisor and the mandibular right first incisor were used for isotopic analysis from the individuals pla-28 and pla-159, respectively (table 1). radiogenic strontium and stable carbon and oxygen isotope analyses were performed on hydroxyapatite in enamel for both teeth. tooth enamel is considered to be generally resistant to post-depositional chemical alteration (budd et al., 2000; lee-thorp and sponheimer, 2003; sillen, 1989). however, it should be noted that since contamination results from the local post-depositional environment, it may cause a false local signal, but not the reverse, making non-local signatures significant (price et al., 2006). in order to characterize the local strontium isotopic signature, burial soil from plaza del castillo was also sampled and analyzed. the enamel and soil samples were prepared at the archaeological chemistry laboratory at arizona state university. teeth were first cast and photographed, and they were mechanically cleaned by abrasion in order to remove any adhering organic matter or contaminants, as well as the outermost layers of tooth which are most susceptible to diagenetic contamination (budd et al., 2000; montgomery et al., 1999; waldron, 1981, 1983; waldron et al., 1979). approximately 10 milligrams of tooth enamel were then removed with a dremel minimite-750 cordless drill equipped with an engraving cutter. the type and the color of the soil sample were first characterized according to munsell soil color charts. approximately two grams were first dried at 120˚c for 48 hours, and then ashed at 800˚c for 10 hours. radiogenic strontium isotope analysis was performed at the w.m. keck foundation laboratory for environmental biogeochemistry at arizona state university. eight milligrams of tooth enamel powder were dissolved in 0.50 ml of 5m hno 3 . the dissolved tooth enamel was evaporated and further dissolved in 0.25 ml of 5m hno 3 . one hundred milligrams of soil were dissolved in 5.0 ml of 5m hno 3 and in 1.0 ml of hf. the soil sample was evaporated and further dissolved in 1.0 ml of 5m hno 3 , 3.0 ml of hcl and 0.5 ml of hf. following this procedure the sample was again evaporated and further dissolved in 1.0 ml of 5m hno 3 . strontium was separated from the sample matrix using eichrom srspec resin, a crown-ether sr-selective substance (100-150 μm diameter), and then loaded into the tip of a glass column. total resin volume was approximately 50 μl. resin was used once for sample elution and discarded. the srspec resin was pre-soaked and flushed with h 2 o to remove strontium present from the resin manufacturing process. the resin was further cleaned in the column with repeated washes of deionized h 2 o and conditioned with 750 μl of hno 3 . the dissolved sample was loaded in 250 μl of 5m hno 3 , washed in 500 μl of 5m hno3, and then the strontium was eluted with 1000 μl of h 2 o. table 1. heavy and light isotope data for archaeological human enamel and soil from plaza del castillo, pamplona laboratory specimen corrected δ13c c(v-pdb) δ18o c(v-pdb) δ18o dw(v-smow) number number materiala 87sr/86sr (‰) (‰) (‰) acl-0400 pla-28 uli1 0.70797 -16.33 -9.65 -16.1 acl-0401 pla-159 lri1 0.70817 -13.57 -5.64 -9.8 acl-0439 pla-0001 soil 0.71119 na na na atooth abbreviations are: uli1= upper left first incisor; lri1= lower right first incisor. residential mobility and dental decoration 48 the enamel and soil samples were analyzed in a neptune multi-collector inductively coupled plasma mass spectrometer (mc-icp-ms) at the w.m. keck foundation laboratory. on april 14, 2007, when the human enamel samples were analyzed, 87sr/86sr analyses of strontium carbonate standard srm-987 yielded a value of 87sr/86sr= 0.71031 ± 0.00003 (2σ, n = 18). on december 7, 2007, when the soil sample was analyzed, 87sr/86sr analyses of strontium carbonate standard srm-987 yielded a value of 87sr/86sr = 0.71028 ± 0.00003 (2σ, n = 14). these data can be compared to analyses of srm-987 using a thermal ionization mass spectrometer (tims), where 87sr/86sr = 0.710263 ± 0.000016 (2σ) (stein et al., 1997), and analyses of srm-987 using an identical mc-icp-ms, where 87sr/86sr = 0.710251 ± 0.000006 (2σ) (balcaen et al., 2005). for oxygen and carbon isotope analysis, approximately 5 milligrams of powdered tooth enamel were treated with 0.24 ml of 2% naocl and then 0.24 ml of 0.1 m ch 3 cooh. carbonate isotopic analyses were performed on a finnigan mat 253 stable isotope ratio mass spectrometer (irms) at the w.m. keck foundation laboratory. replicates of nbs19 resulted in a reproducibility of ±0.2‰ for δ18o and ±0.2‰ for δ13c. when necessary, the following conversion equations were used: δ18o vsmow = (1.03091 × (δ18o vpdb )) + 30.91, δ18o vpdb = (0.97002 × δ18o vsmow ) – 29.98, δ18o c(vsmow) = (8.5 + (δ18o p ))/0.98, and δ18o p(vsmow) = (0.64 × (δ18o dw )) + 22.37 (coplen et al., 1983; iacumin et al., 1996; müller et al., 2003; wolfe et al., 2001). results the enamel sample from individual pla-28 exhibits 87sr/86sr = 0.70797, δ18oc =-9.7‰, and δ13c c = -16.3‰ (table 1). the enamel sample from individual pla-159 exhibits 87sr/86sr = 0.70817, δ18o c = -5.6, and δ13c c = -13.6‰ (table 1). using the previously-discussed conversion equations the δ18o c values from the enamel were converted to likely drinking water values δ18o dw(v-smow) = -16.1‰ for pla-28, and δ18o dw(v-smow) = -9.8‰ for pla-159 (table 1). the soil sample shows a ratio of 87sr/86sr = 0.71119 (table 1). discussion before we turn to the interpretation of the biogeochemical results, we will briefly examine the geochemical setting of the study area. pamplona basin is located in the western part of the southern pyrenean foreland basin, and consists of geologic transitional marine and terrestrial deposits that formed in the lower to middle eocene (payros et al., 1999). the valle de tena in huesca province, located to the northeast of pamplona, is characterized by silurian to permian and cretaceous carbonate and detrital sedimentary rocks, with the paleozoic limestones showing isotopic values of 87sr/86sr = 0.70510-0.70970 (subías et al., 1998) (fig. 1). the deposits of fluorites and calcites in the area exhibit isotopic ranges of 87sr/86sr = 0.70850-0.71083 in portalet, 87sr/86sr = 0.70858-0.71036 in lanuza, and 87sr/86sr = 0.70911-0.71010 in tebarray (subías et al., 1998). furthermore, the andesites in anayet exhibit a ratio of 87sr/86sr = 0.70582-0.70752 (innocent et al., 1994) (fig. 1). the volcanic and intrusive alkaline rocks in oloron in southern france show an isotopic range of 87sr/86sr = 0.70535-0.70623 (rossy et al., 1992) (fig. 1). to the west of pamplona, basalts from the region of bilbao in the spanish basque country give an isotopic range of 87sr/86sr = 0.70376-0.70542 (rossy et al., 1992) (fig. 1). in order to control for the wide petrographic diversity and intraregional bedrock variation, soil from plaza del castillo was used to determine the local isotopic baseline of the area for this preliminary study. when radiogenic strontium isotopic signatures from both enamel samples are compared to the local geochemical signal for the soil, they prove to be considerably lower (table 1). this may indicate that both individuals were born and spent at least early childhood in a different location and moved to pamplona later in life, assuming local dietary and water sources were consumed. in an attempt to trace the geographic origins of both individuals and thus test the hypothesis of a north african provenance, isotopic signatures from enamel were compared to radiogenic strontium isotopic ratios reported for africa. in northeastern morocco, the region approximately 100 km southwest to the city of oujda shows a series of granodiorites with ratios of 87sr/86sr = 0.706930.70972 (ajaji et al., 1998). groundwater sampled across numerous locations along the continental intercalaire aquifer system, spanning from the saharan atlas of algeria to the chotts region of southern tunisia, yields isotopic ratios of 87sr/86sr = 0.707826-0.70939 (edmunds et al., 2003). furthermore, cumulate rock sequences at laouni, hoggar, in southern algeria exhibit a range of 87sr/86sr = 0.70305-0.70669 (cottin et al., 1998). finally, soil samples and modern faunal samples collected in the gobero area in central niger show average ratios of 87sr/86sr = 0.71290 ± 0.00064 (1σ) and 87sr/86sr = 0.71261 ± 0.00116 (1σ), respectively (sereno et al., 2008). hence, the radiogenic strontium isotopic signatures of the two individuals analyzed from plaza del castillo generally match the radiogenic strontium isotopic ratios from northeastern morocco, thus supporting a north african origin of berber groups, such as those who colonized medieval pamplona during the early medieval period. the enamel radiogenic strontium isotope signatures from plaza del castillo are also consistent with some marine strontium sources, averaged with strontium from a geologic zone or zones with lower strontium isotope signatures. since seawater is characterized by 87sr/86sr = 0.7092 (veizer, 1989), these individuals may have obtained some, though not all, of their strontium in the first years of life from marine sources. however, according to the results from stable carbon isotope analysis discussed below this interpretation is unlikely, given that marine food consumption was not a major component of the diet of the two individuals. e. prevedorou et al. 49residential mobility and dental decoration given that the climate in northern spain is considered to be relatively stable since the eighth century a.d., modern δ18o v-smow values from precipitation were used to determine the local range of δ18o v-smow . due to the lack of available precipitation values for pamplona, precipitation δ18o v-smow values measured in saragossa (fig. 1) were used to determine the probable δ18o v-smow values in pamplona (iaea/wmo, 2006). oxygen isotope signatures in precipitation collected in the saragossa station in 2000-2001, showed a range from δ18o v-smow = -10.8‰ to δ18o v-smow = 1.67‰, with an average value of δ18o v-smow = -5.9 (n = 24) (iaea/wmo, 2006), which was used as the probable local range of δ18o v-smow for pamplona. when the drinking water values from plaza del castillo are compared to the modern precipitation values from saragossa, the δ18o v-smow value for individual pla-28 (-16.1‰) falls outside the range of the observed precipitation values. the δ18o v-smow value for pla-159 (-9.8‰) appears within the local precipitation range; however, it is very close to the lower limit. thus, analysis of δ18o v-smow values may indicate that these two individuals lived outside of the pamplona region during enamel formation, paralleling results from the strontium analysis. as mentioned, bone carbonate reflects the isotopic composition of the diet plus 9.4‰ (ambrose and norr, 1993). therefore, subtracting 9.4‰ from the measured archaeological human enamel δ13c c(v-pdb) values shows that they correspond to a diet based heavily on c 3 plants and/or animals that consumed c 3 plants (table 1). the reconstruction of a diet based on terrestrial c 3 plants, like cereals, is consistent with either african or spanish early childhood residence. conclusions overall, the presence of two first-generation immigrants at the islamic cemetery of plaza del castillo was successfully identified through isotopic analyses. the two individuals (pla-28, pla-159) showed non-local isotopic signatures suggesting movement to pamplona from a different geographic location sometime after early childhood. an origin from northern africa, as suggested by the typological analysis of the dental modifications in pla-159, is consistent with the isotopic results. dental decoration, the apparent early date for at least part of the cemetery and these isotopic results suggest that the individuals included in the study may have come to pamplona from north africa, perhaps as part of the military expedition to control the local revolutions of the time against the recently established muslim authority. the fact that individual pla-159 is a female further indicates that the incoming muslim population was not formed exclusively by men with a military function, but rather by family groups and/or camp followers. given the promising results of this preliminary study, future research consisting of isotopic analysis of a larger sample size, representative of the maqbara, will allow for a complete examination of the residential histories of the individuals buried in plaza del castillo and will inform our understanding of the migration of african groups in eighth century a.d. pamplona during the initial islamization of the city. in addition, a vital direction for further research is the continued characterization of baseline isotopic and elemental data from pamplona and the surrounding region, including the bioavailable strontium isotope ratios in the study region and paleoenvironmental reconstructions. detailed data on strontium isotope ratios in exposed bedrock samples from the geological literature should be supplemented with strontium isotope analysis of modern and archaeological small mammals from the study region. this will facilitate characterization of local strontium isotope signatures and a more informed interpretation of the geographic origin of the individuals interred in plaza del castillo. in conclusion, the present study exemplifies the use of biogeochemistry as an analytical tool, and provides a new perspective to the muslim diaspora in northern spain. acknowledgments we would like to thank a. anbar and e. shock for access to the w.m. keck foundation laboratory for environmental biogeochemistry at asu and postdoctoral associates gwyneth gordon and anthony michaud for assistance with sample analysis. we would like to thank 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demography and ethnic continuity in the tlailotlacan enclave of teotihuacan: the evidence from stable oxygen isotopes. j anthropol archaeol 23:385-403. wolfe bb, aravena r, abbott mb, seltzer go, gibson jj. 2001. reconstruction of paleohydrology and paleohumidity from oxygen isotope records in the bolivian andes. paleogeogr paleoclimatol paleoecol 176:177-192. e. prevedorou et al. hopkinson et al. 2008.2 12 santa maria cathedral in vitoria, spain, began as a simple parish church in 900 ce. additional construction over the next thousand years eventually compromised the church’s structural stability. this necessitated major renovations that began in 1997 and continue to the present. to stabilize the foundations, excavations within and around the cathedral displaced over 1,500 burials. in 2006, a dental study was initiated on skeletons from burial sites dating to medieval and post-medieval times. while making observations on tooth size, morphology, and pathology, an unusual phenomenon was observed. eighteen individuals had jaws, teeth, and, on two occasions, hyoid bones that had been stained varying shades of green (fig. 1). the staining was inferred to be the result of copper leeching out of grave goods placed in close proximity to the affected areas. direct evidence for this relationship was provided when a bronze coin was found fused to the occlusal surface of an upper left second molar (fig. 2). chemical modeling supports the conclusion that the green staining was caused by the copper component of bronze coins placed in the mouths of individuals prior to burial. samples the santa maria cathedral burials came from two temporally and geographically distinct areas. series 17, dating to medieval times (<1,500 ce), was excavated immediately outside the cathedral. series 11 and 22 contain post-medieval (>1,500 ce) remains buried directly under the floors of the cathedral. the medieval sample numbered 77 individuals while the post-medieval sample consisted of 129 individuals (table 1). only skeletons that possessed the anatomical areas most likely to be subject to staining, the skull and mandible, are included in these samples. in the medieval sample, 9 of 77 (11.7%) individuals exhibited green staining while 9 of 129 (7.0%) skeletons showed staining in the post-medieval sample. there was no significant difference in the frequency of green staining between the two time periods (χ2 = 1.37; p > 0.05). when the medieval and post-medieval samples were pooled, 6 of 68 males (8.8%) and 8 of 89 females (9.0%) exhibited green staining. the difference between the sexes is not significant (χ2 = 0.00; p > 0.05). additionally, 4 of 39 (10.2%) children of unknown sex exhibited staining. although the total sample of stained jaws and teeth is relatively small, there were no discernable significant differences by time, sex, or age. burials, bronze coins and the boatman the explanation for putting coins in the mouth at death is found in classical greek mythology. the ritual of “paying the boatman” stems from the myth of charon who ferried the souls of the dead across an underground river to hades, the final destination for all souls, sinner and saint alike. the name of the fabled waterway that had to be crossed was the styx (‘hated’) for whom the coin tolls: green stained teeth and jaws in medieval and post-medieval spanish burials kimberly a. hopkinson, sarah m. yeats, and g. richard scott department of anthropology, university of nevada reno, reno, nevada abstract: while observing dental characteristics in spanish and basque skeletons from the cathedral of santa maria in vitoria, spain, an unusual pattern of staining was evident in 18 of 206 individuals. the stain, which permeated bone, dentine, calculus, and/or enamel, varied in color from bright green to turquoise. males and females, all age categories, and medieval and post-medieval skeletons were equally affected. the green stain was the result of an ancient practice going back to greek times that involved placing a silver or gold coin (obol) in the mouth of the deceased prior to burial for the purpose of paying the boatman (charon) for passage across the river of woe (acheron). in spain, bronze coins substituted for silver and gold. the copper component of the bronze reacted with the acidic environment caused by decomposition creating basic copper carbonate. the copper carbonate then seeped into the porous spaces of the bones and teeth or replaced the mineral portion of the bone. the duration of this practice provides evidence that a seemingly ‘pagan’ ritual was preserved long after christianity spread throughout spain. dental anthropology 2008;21(1):12-17. correspondence to: g. richard scott, department of anthropology, university of nevada reno, reno, nevada 89557 e-mail: grscott@unr.edu 1� or the acheron (‘morning’ or ‘woe’). charon does not figure as prominently as other supernatural beings in early greek literature or artwork. there are possible allusions to charon in some of homer ’s works, and the boatman was likely a part of greek oral tradition before he is first referenced in literature (sullivan, 1950). the few early depictions describe him as a man poling a raft full of shades, making him a rarely mentioned but crucial part of the soul’s journey (fig. 3). he would charge the souls an obol (athenian coins from the 5th-6th century bce) to be ferried to the afterlife. the obol was placed in the mouth of the dead before burial so that upon their arrival at the riverbank, they would already have the fee. those who lacked the fee were doomed to wander the banks for one hundred years (fairbanks, 1912), a fate similar to limbo in catholicism. early roman mythology also included charon as the romans adopted much of greek religious tradition. virgil’s epic poem, the aeneid, describes charon as an elderly man “repulsive in frightening filth … [with] a matted and wolf-grey beard … [and] dirtsoiled clothes” (ahl, 2007:37). the only latin novel that survived in its entirety, apuleius’ metamorphose, written in the mid to late second century ce, refers to charon as an avaricious and filthy old man who gathers tolls and ferries souls across the river (butler, 1910). as the romans invaded and conquered other lands this myth was integrated into new cultures. from the 2nd century bce to the 5th century ce, the romans had a major impact on northern spain. ultimately, the romans were as responsible for the decline of this burial custom as they were for its introduction. roman emperor constantine i introduced and legitimized mainstream christianity to europe in the 4th century ce. eventually the christian hierarchy stigmatized ‘pagan’ rituals that were part of the dogma of competing religions. during the late 6th and early 7th centuries, pope saint gregory i created many christian superstitions and legends about death and the afterlife. these legends were used to reach the faithful and eradicate lingering pagan myths by using a simple language that the lower classes could understand. one of st. gregory’s stories involved a dead soldier who, upon his resurrection, described his passage to the afterlife as being facilitated by a bridge that was suspended over a dark and rancid river (gurevich, 1992). theoretically, the ‘pagan’ ferryman had been replaced by a christian bridge and coins were no longer necessary to pass into the hereafter. not all christian authorities sought to exorcise charon from stories about the afterlife. it became the practice of many medieval and renaissance writers to appropriate figures from pagan mythology into their ecclesiastical writings, transforming them into demons. charon was no longer an integral and necessary part of the death process ferrying souls to their respective fates. instead, he was transformed into a demon that transported only the damned to hell. christian poet dante described him as “charon the demon, with eyes like glowing coals … he beats with his oar whoever lingers” (durling, 1996). this metamorphosis can be seen in church sanctioned artwork such as michelangelo’s depiction of charon from the “last judgment” (fig. 4). despite the power of the catholic church, the pagan belief of paying the boatman survived into medieval and post-medieval times, though at a reduced rate. at santa maria, 8.7% of the individuals had green staining on their jaws and/or teeth. this shows the ritual of placing coins in the mouths of the dead, even though it had survived, was not widely practiced between 900 and 1,850 ce. fig. 1. stained mandible of child (medieval period). sex n affected percent medieval male 23 3 13.0 female 29 5 17.2 unknown 25 1 4.0 total 77 9 11.7 post-medieval male 45 3 6.6 female 60 3 5.0 unknown 24 3 12.5 total 129 9 7.0 combined male 68 6 8.8 female 89 8 9.0 unknown 49 4 8.2 total 206 18 8.7 table 1. frequencies of staining, by temporal phase green stained teeth and jaws 14 chemistry and copper formation of copper carbonate there are two possible chemical causes for the green stain. explanations begin with the premise that the copper component (cu0) of the bronze coins (fig. 5) reacted with h+ ions, resulting in the formation of cu2+. cu2+ then reacted with water and carbon dioxide to create basic copper carbonate (cu2+co � . cu2+(oh) 2 ), commonly known as patina (sax and lewis, 1987). this greenish-grey compound is the normal result of copper oxidation. the h+ ions, water and co 2 are all normal byproducts of body decomposition. the creation of basic copper carbonate is shown in the following chemical reaction: cu0 h +  → cu2 + h 2 o ,c o 2 → cu2 + co � cu2 + (oh) 2 patina, evident in fig. 6, is resting on the biological material but is not incorporated into the bone. incorporation could be the result of two different processes. fig. 2. bronze coin fused to upper second molar (medieval period). explanation 1: absorption of copper carbonate the basic copper carbonate, in an aqueous instead of solid form, may be seeping into the porous spaces of the bones and teeth. if simple absorption were occurring, it would be expected that the affected biological material would resemble the copper carbonate in color. explanation 2: formation of pseudomalachite an alternative explanation is that copper replaced the calcium component of the bone and turned the mineral portion of the bones and teeth, hydroxylapatite (sax and lewis, 1987), into pseudomalachite. pseudomalachite, named for its chemical and physical similarities to true malachite (bailey, 1929), is a different color from basic copper carbonate. the latter is a grayish blue-green while the former ranges from a pale green, a yellow green, or an almost black color when concentrated. this gradient may be represented in fig. 7, although the black portion of the tooth may reflect decomposition. the fact that the stained bones and teeth resemble the green of pseudomalachite in color k.a. hopkinson et al. 15 instead of the grayish blue-green of copper carbonate supports this second explanation. in the first part of this process, the mineral portion of the bone and teeth, hydroxylapatite, reacts with h+ ions already present as a result of normal body decomposition. this results in the creation of free calcium (ca2+), hydrogen phosphate (hpo 4 2-) and water (h 2 o). the chemical process is as follows: ca 10 (po 4 ) � (oh) 2 h + → 10ca2+ + 6hpo 4 2+ h 2 o the free calcium is washed away by groundwater or other liquids created during the decomposition process. the basic copper carbonate created during the first chemical reaction then combines with the hydrogen phosphate to create carbon dioxide, water, free phosphate, and pseudomalachite. the chemical formula for pseudomalachite is the same as that of hydroxylapatite, the only difference being that copper replaces calcium. the chemical process for the incorporation of copper into the mineral composition of bone is as follows: cu2+c0 � .cu2+(oh) 2 +6hpo 4 2 → 5co 2 +5h 2 o+ 2cu 5 (po 4 ) 2 (oh) 2 +8po 4 2conclusions there are other possible explanations for the presence of green stained jaws and teeth in the santa maria burials, including copper in the soil, groundwater or other grave goods. however, the localization of the green stain in the oral cavity and associated anatomical areas, as well as the presence of one bronze coin found adhering to a tooth, support the proposition that family members were placing bronze coins in the mouths of their loved ones at death. this speaks to the fact that the influence of the christian church, at least in medieval and post-medieval spain, was not all encompassing. almost 10% of the congregation of the cathedral combined elements of both christian and ‘pagan’ burial practices, hedging their bets on what would be required during their journey to the afterlife. acknowledgements the authors wish to express their sincere appreciation to professor agustin azkarate who allowed one of us (grs) to examine the large skeletal collection excavated under his direction. we would also like to thank the archaeological staff at the cathedral of santa maria, including ismael garcía-gómez and leandro sanchez, for their help in facilitating this research. special thanks are due to rafael martinez-jausoro and jaione agirre-garcia for their translational skills and many kindnesses. dr. jason shearer provided the chemical expertise for the project and helped the authors with fig. 3. greek pot depicting the boatman charon (the lekythos vase, housed at the national archaeological museum, athens, greece). green stained teeth and jaws 1� the molar equations shown in the text. literature cited ahl f (translator). 2007. virgil’s the aeneid. new york: oxford university press. durling rm (translator). 1996. dante’s the divine comedy. vol 1: inferno. new york: oxford university press. butler he (translator). 1910. apuleius’ the metamorphoses or the golden ass. oxford: clarendon press, 1910. bailey d, bailey k. 1929. an etymological dictionary of chemistry and mineralogy. london: edward arnold and company. fairbanks a. 1912. mythology of greece and rome. new york: d. appleton and company. gurevich a. 1992. historical anthropology of the middle ages. chicago: the university of chicago press. lamarche-vadel b. 1986. michelangelo. paris: nouvelles editions francaises. lekythos vase with charon and hermes. national archaeological museum, athens. accessed on 2 april 2008 on university of arkansas campus resources website at http://www.uark.edu/ campusresources/dlevine/religionimages.ht ml. sax ni, lewis rj, sr. 1987. hawley’s condensed chemical dictionary, 11th ed. new york: van nostrand reinhold company. sullivan fa. 1950. charon, the ferryman of the dead. the classical journal 46:11-17. fig. 5. bronze coin recovered from oral cavity of burial from santa maria cathedral. k.a. hopkinson et al. fig. 4. michaelangelo’s depiction of charon from the sistine chapel (lamarche vadal, 1986). 17 fig. 6. basic copper carbonate adhering to mandible (medieval period). fig. 7. possible pseudomalachite gradient around a carious lesion on the lower molars (medieval period). green stained teeth and jaws brook et al. 2013.1 3 the development of the mammalian dentition as a complex adaptive system alan h. brook 1,2 , toby e. hughes 1 , grant c. townsend 1 , richard n. smith 3 and matthew d. brook o’donnell 4 1school of dentistry, university of adelaide, 2school of dentistry, queen mary university of london 3dental school, university of liverpool, 4annenberg school for communication studies, university of pennsylvania complex systems are widespread in biological systems and communities. interacting adaptive entities produce dynamic patterns and structure. in a biological complex adaptive system the interaction of lower level components leads to the emergence of high level phenomena and structures. such systems have the general characteristics of self-adaptation, self-organisation, emergence, multitasking, robustness, critical phases, diversity and compatibility, with such statistical properties as thresholds and scale free networks (barabasi, 2003; camzine et al., 2003; mitchell, 2009). the aim of this study was to investigate whether development of the dentition exhibits the general and statistical characteristics of a complex adaptive system by examining data on normal and abnormal dental development. dental development key characteristics of dental development are that it is multi-levelled, has multiple interactions, is multi-factorial, is multidimensional and is progressive over time (brook, 2009). the core components of this process are summarised in table 1 and are illustrated in figure 1. the dentition as a complex system the next step is to examine the components of dental development against the key characteristics of complex systems. self-organisation and emergence are evident as tooth germs emerge from molecular level interactions (lesot and brook, 2009)and then progressively develop and grow in size and shape until they commence calcification and form mature teeth. the initiation of tooth germs occurs at specific sites within a field and they progress to form different shapes and sizes, so that the calcified macroscopic teeth which emerge are discrete but organised into groups that have different shapes and functions around the dental arch. abstract general characteristics of complex adaptive systems include self-adaptation and organisation, emergence, multitasking, robustness, critical phases, diversity and compatibility with such statistical models as thresholds and scale free networks. the aim was to investigate whether dental development exhibits the general and statistical characteristics of a complex adaptive system, by examining data on normal and abnormal dental development. the findings were that self-adaptation and organisation occur while interactions between genes, epigenetic and environmental factors lead to the emergence of cells, tooth germs and mineralised teeth. multitasking occurs as signalling pathways act simultaneously and reiteratively during initiation and morphogenesis. tooth germs that do not attain a critical threshold during development may undergo apoptosis. diversity is evident in tooth number, size, shape and mineralisation. statistical investigation shows that males have significantly larger teeth and higher prevalences of megadontia and supernumerary teeth (p<0.05), supporting brook’s threshold model which is further developed here to include shape. image analysis of tooth dimensions showed they followed a power law distribution, with the first 8 of 34 factors in upper lateral incisors accounting for 94.4% of the total variation. in conclusion, the development of the dentition shows the general and statistical characteristics of a complex adaptive system. correspondence to: alan brook, school of dentistry, university of adelaide, adelaide, south australia, 5005 email: alan.brook@adelaide.edu.au telephone: +61 (0)8 8313 2910 keywords: complex systems, networks, dental development 4 fig. 1. the multilayered developmental process of tooth formation illustrating the molecular changes within the cells and tissues and the macroscopic outcomes (part of figure from http://bite-it.helsinki.fi/). table 1. the key characteristics and components of dental development characteristic components multilevel mature tooth cells, tissues, tooth germs molecular multiple interactions tooth germ – tooth germ cell – matrix cell – cell gene – epigenetic – environment gene – gene multifactorial environmental – local / systemic epigenetic – narrow / broad over 300 genes multidimensional spacial – x, y, z dimensions time progressive over time each dentition tooth type / morphogenetic field each tooth 5 the outcome is an integrated, balanced, complex system. it is a major characteristic of a complex system that the mature units bear no resemblance to the precursor entities. self-adaptation is demonstrated by the within -species and between-species diversity that is found. in humans, variations in the number, size, shape and mineralisation of teeth occur frequently (brook et al., 2009; townsend et al., 2009). between species variation in these parameters is also extensive (hillson, 1986).one of the factors to consider is the adaptive interaction that can occur between developing tooth germs, with the timing of development of each being important. timing is also significant in the critical phases of dental development. for progression from the initial phase to morphogenesis (fig. 1), transcription factors in the msx, dlx and lhx families are required. the tooth germ may undergo apoptosis if this progress does not occur at this critical time. similarly, if the matrix proteins are not removed during enamel calcification, defects in mineralisation result. robustness in the development of the dentition comes from the satisfactory functioning of the system even in the presence of variations and moderate developmental defects. mature teeth have some ability to self-repair and continue to develop in response to environmental challenges, a property akin to self-awareness. this robustness is also associated with excess capacity: genes are switched on and off and function reiteratively in multiple tissues; genes can also be up-regulated, down-regulated and, if their function is defective, other genes sometimes function to produce the necessary product; genes in function can be alternatively spliced and the products varied in amount and nature. multitasking adds to this robustness as signalling pathways act simultaneously and reiteratively. similarly, the ameloblasts control the secretion and later removal of the enamel matrix proteins, as well as the deposition of the minerals. statistical models based on epidemiological and clinical data, brook (1984) developed a model to explain the relationship between the prevalence of dental anomalies of number and size. this model is based on a normal distribution on which thresholds are superimposed beyond which microdontia, hypodontia, megadontia and supernumerary teeth occur. here the model is further developed to include shape (fig. 2). as tooth size moves closer to the thresholds that determine variation in tooth number, teeth tend to display abnormal shape as well as size. an example is the diminutive perma fig. 2. this development of the threshold model of brook (1984) now incorporates the shape changes seen at the extremes of tooth size. 6 nent upper lateral incisor which is often ‘pegshaped’ as well as being very small. the developmental process underlying these clinical findings and modelling has been elucidated in molecular genetics and histological studies (brook, 2009; lesot and brook, 2009). the scale free network model reflects findings that when the frequencies of each of the components in some systems are plotted, the result is a power law distribution (fig. 3). this distribution occurs when a few components occur with a high frequency and the large majority occur with lower frequency. in a principal component analysis of 34 dimensions in upper incisor teeth, 94 per cent of the total variance was accounted for by 7 dimensions (khalaf et al., 2009), thereby displaying the properties of a scale free network. conclusions the dentition exhibits the characteristics of a complex adaptive system, both in development and in its mature form. during evolution it has become adapted to different environments. it serves as a valuable model for investigating how genetic, epigenetic and environmental factors interact during somatic development. acknowledgments this project was part of the studies funded by wellcome programme grant 3256. literature cited barabasi al. 2003. linked. plume books. penguin group new york. brook ah. 1984. a unifying aetiological explana tion for anomalies of tooth number and size in humans. arch oral biol 29:373-378. brook ah. 2009. multilevel complex interactions between genetic, epigenetic and environmental factors in the aetiology of anomalies of dental development. arch oral biol 54:s3-s17. brook ah, griffin rc, smith r, townsend gc, kaur g, davis gr, fearne g. 2009. tooth size patterns in patients with hypodontia and super numerary teeth. arch oral biol 54:s63-s70. camazine s, deneubourg j-l, franks nr, sneyd j, theraula g, bonabeau e. 2003 self-organization in biological systems. princetown, nj: princeton university press. hillson s. 1986. teeth. cambridge university press. khalaf k, smith rn, elcock c, brook ah. 2009. multiple crown variables of the upper inci sors in patients with supernumerary teeth com pared with controls. arch oral biol 54:s71 s78. lesot h, brook ah. 2009. epithelial histo genesis during tooth development. arch of oral biol 54:s25-s33. mitchell m. 2009. complexity. a guided tour. ox ford university press. townsend g, harris ef, lesot h, clauss f, brook ah. 2009. morphogenetic fields within t h e h u man dentition: a new, clinically relevant synthesis of an old concept. arch oral biol 54: s34-s44. fig. 3. a typical power law distribution where a few factors occur frequently in a system gamza 2010.6 66 analysis of dental microwear has aided in the interpretation of human diet for a number of populations over the last few decades (e.g., fine and craig, 1981; harmon and rose, 1988; hojo, 1989; laleuze et al., 1993; molleson et al., 1991; 1993; danielson and reinhard, 1998; schmidt, 2001; teaford, 2002; organ, 2005). the majority of these studies rely on microwear of permanent dentition; only a few have used the deciduous dentition (bullington, 1991; greene, 2007). despite investigations into gordon’s claims (1980, 1982) that microwear varies with age (teaford and oyen, 1986, 1988, 1989; bullington, 1991), no study has compared the microwear of deciduous and permanent teeth. this aim of the present study is to determine if microwear patterns differ between deciduous and permanent molars of the same individual. given the same diet, can deciduous and permanent enamel be expected to show similar microwear patterns? we know that the physical and chemical properties of deciduous and permanent enamel differ (legeros et al., 1983; kornblit et al., 2009). enamel of deciduous teeth is somewhat softer than that of the permanent dentition. this is due to the spatial organization of the enamel prisms, which is more loosely organized in deciduous enamel. often, superficial deciduous enamel is aprismatic (kornblit et al., 2009). it also tends to be less mineralized and more porous (legeros et al., 1983; kornblit et al., 2009). several studies have shown that deciduous enamel erodes at a faster rate than permanent enamel when exposed to acids (amaechi et al., 1999; hunter et al., 2000; lippert et al., 2004). lippert and colleagues (2004) show that deciduous enamel is significantly softer after being exposed to acid and therefore at higher risk of abrasion and attrition than permanent enamel. given a faster rate of wear and higher predisposition of deciduous enamel to abrasion, a greater number of microwear features or larger microwear features might be expected. materials and methods a total of 11 individuals were chosen for the study; five from hierakonpolis and six from naqada. both locations are predynastic sites in upper egypt dating to 3,800-3,650 bc. the two sites have been shown to have similar diets (greene, 2007). individuals in this sample fell within the 6 to 12 year age range and had both a deciduous second molar and permanent first molar erupted and in occlusion. while most researchers use the mandibular left second molar (gordon, 1982; harom and rose, 1988; kay, 1987; schmidt, 1998), deciduous molars would not be expected to remain in occlusion until the eruption of the second molar. casts of the teeth were prepared following schmidt (1998). casts were separated and given unique random numbers so the researcher did not know which teeth were a pair during study. micrographs were taken of the phase ii wear facet (as defined by kay, 1977). images were obtained on an international scientific instruments (isi40) sem at 500x magnification in the secondary emissions mode (teaford and walker, 1984; teaford, 1984, 1991, 1994; teaford et al., 1996). images were transferred directly from the sem to computer via an iridium digital imaging system. a semi-automated computer program, microwear 4.0 (ungar, 2000), was used to analyze digital images of the tooth surface. microwear characteristics examined include total number of features (pits and scratches), total number of pits, mean breadth of pits, and mean breadth of scratches (table 1). comparisons were made between the deciduous and permanent molar using paired-sample t-tests. short communication: intra-individual microwear variation: deciduous versus permanent dentition tammy r. gamza department of anthropology, southern illinois university-carbondale, il correspondence to: tammy r. gamza, department of anthropology, mail code 4502, southern illinois university carbondale, carbondale, illinois 62901 e-mail: gamza@siu.edu abstract this study compares microwear patterns on deciduous and permanent dentition within individuals. number of features, total number of pits, mean pit breadth and mean scratch breadth are compared in 11 individuals aged 6-12 years. for each individual, the second deciduous molar and first permanent molar are used. paired sample t-tests show no significant difference between deciduous and permanent enamel for any of the microwear features examined. this study suggests that differences in the physical and chemical structures of deciduous and permanent enamel are not sufficient to cause differences in microwear patterning. any difference between juveniles and adults can be assumed to represent a true dietary difference rather than enamel structural differences. dental anthropology 23(2):66-68. 67 results and discussion the differences between the deciduous and permanent molar were generally small for all individuals. figure 1 shows the deciduous and permanent dentitions with the greatest overall differences. the average feature tally differs by 13 features, with the majority differing by less than 10 features. the average pit tally differs by only five pits, with the majority differing by less than five. mean pit breadth differs by 0.1 μm to 4.44 μm, with the majority differing by less than 2 μm. one individual was not included in the test for mean pit breadth because this individual did not exhibit any pits on the deciduous molar. mean striation breadth differs by 0.29 μm to 8.58 μm, with the majority differing by less than 1 μm. paired-samples t-tests showed no significant difference between the deciduous and permanent molars for any of the characteristics examined (table 2). the results of this study suggest that, despite some small differences, the deciduous and permanent enamel generally react the same way in regard to microwear features. although the deciduous and permanent teeth were not identical in each individual, the differences were no greater than intertooth differences between first and second permanent molars of the same individual (mahoney, 2006). therefore, subadults with deciduous dentition can reasonably be included in population studies of microwear. also, any difference in microwear patterns between juveniles and adults within a population should represent actual dietary differences rather than differences in enamel structure. acknowledgments i would like to thank dr. renee friedman, director of the hierakonpolis expedition for permission to study the hierakonpolis sample and for her hospitality during my stay at hierakonpolis. i thank dr. maggie bellatti and dr. robert foley of the leverhulme center for human evolutionary studies at the university of cambridge for permission to study the naqada sample. travel was made possible by a nsf grant (#bcs-0119754) awarded to jerome rose of the university of arkansas. use of the scanning electron microscope was possible thanks to the deans’ special projects fund, college of natural science and mathematics, university of alaska fairbanks. literature cited amaechi bt, higham sm, edgar wm. 1999. factors influencing the development of dental erosion in vitro: enamel type, temperature and exposure time. j oral rehabil 26: 624–630. bullington j. 1991. deciduous dental microwear of prehistoric juveniles from the lower illinois river valley. am j phys anthropol 84:59-73. danielson dr, reinhard kj. 1998. human dental microwear caused by calcium oxalate phytoliths in prehistoric diet of the lower pecos region, texas. am j phys anthropol 107:297-304 fine d, craig gt. 1981. buccal surface wear of human premolar and molar teeth: a potential indicator of dietary and social differentiation. j hum evol 10:335344. gordon kd. 1980. dental attrition in the chimpanzee (pan troglodytes uersus): a scanning electron microscope study. ph.d. dissertation, yale university, new haven, ct. gordon kd. 1982. a study of microwear on chimpanzee molars: implications for dental microwear analysis. table 1. mean values and standard deviations for deciduous and permanent molars deciduous molars permanent molars mean sd mean sd total number of features 35.18 24.28 47.73 34.42 total number of pits 17.45 15.08 22.55 22.56 mean pit breadth 8.63 5.66 9.46 4.86 mean striation breadth 3.65 2.53 2.86 1.06 fig. 1. microwear images showing the greatest difference between deciduous and permanent dentition represented in this sample: (left) deciduous dentition; (right) permanent dentition. table 2. paired-sample t-tests between deciduous and permanent molars variable t df p total number of features -1.315 10 0.218 total number of pits -0.741 10 0.476 mean pit breadth -0.952 9 0.366 mean striation breadth 0.886 10 0.396 microwear variation t.r. gamza am j phys anthropol 59:195-215. greene tr. 2007. diet and dental health in predynastic egypt. berlin: vdm verlag dr. muller. harmon am, rose jc. 1988. the role of dental microwear analysis in the reconstruction of prehistoric diet. in: kennedy bv, le moine gm, editors. diet and subsistence: current archaeological perspectives. calgary, alberta: archaeological association of the university of calgary. p 267-272. hojo t. 1989. dietary differences and microwear on the teeth of late stone age and early modern people from western japan. scan microsc 3:623-628. hunter ml, west nx, hughes ja, newcombe rg, addy m. 2000. erosion of deciduous and permanent dental hard tissue in the oral environment. j dent 28:257-263. kay rf. 1977. the evolution of molar occlusion in the cercopithecidae and early catarrhines. am j phys anthropol 46:327-352. kay rf. 1987. analysis of primate dental microwear using image processing techniques. scan microsc 1:657-662. kornblit r, bossu m, mari d, rocca jp, polimeni a. 2009. enamel and dentine of deciduous teeth er:yag laser prepared. a sem study. eur j paed dent 10:75-82. lalueza fox c, pérez-pérez a. 1993. the diet of the neanderthal child gibralter 2 (devils’ tower) through the study of the vestibular striation pattern. j hum evol 24:29-41. legeros rz, piliero ja, pentel l. 1983. comparative properties of deciduous and permanent (young and old) human enamel. gerodontology 2:1-8. lippert f, parker dm, jandt kd. 2004. susceptibility of deciduous and permanent enamel to dietary acidinduced erosion studied with atomic force microscopy nanoindentation. eur j oral sci 112:61-66 mahoney p. 2006. brief communication: intertooth and intrafacet dental microwear variation in an archaeological sample of modern humans from the jordan valley. am j phys anthropol 129:39-44. molleson t, jones k. 1991. dental evidence for dietary change at abu hureyra. j archaeol sci 18:525-539. molleson t, jones k, jones s. 1993. dietary change and the effects of food preparation on microwear patterns in the late neolithic of abu hureyra, northern syria. j hum evol 24:455-468. organ jm, teaford mf, larsen cs. 2005. dietary inferences from dental occlusal microwear at mission san luis de apalachee. am j phys anthropol 128:801-811. schmidt cw. 1998. dietary reconstruction in prehistoric humans from indiana: an analysis of dental macrowear, dental pathology, and dental microwear. ph.d. dissertation, purdue university. schmidt cw. 2001. dental microwear evidence for a dietary shift between two nonmaize-reliant prehistoric human populations from indiana. am j phys anthropol 114:139-145. teaford mf. 1984. molar microwear and diet in the genus cebus. am j phys anthropol 66:363-370. teaford mf. 1991. dental microwear: what can it tell us about diet and dental function? in: kelley ma, larsen cs, editors. advances in dental anthropology. newyork: wiley-liss. p 341-356. teaford mf. 1994. dental microwear and dental function. evol anthropol 3:17-30. teaford mf. 2002. dental enamel microwear analysis. in: hutchinson dl, editor. foraging, farming and coastal biocultural adaptation in late prehistoric north carolina. gainesville, florida: university press of florida. p 169-177. teaford mf, oyen oj. 1986. dental microwear in vervets raised on different diets. am j phys anthropol 69:270. teaford mf, oyen oj. 1988. in vivo and in vitro turnover in dental microwear. am j phys anthropol 75:279. teaford mf, oyen oj. 1989. in vivo and in vitro turnover in dental microwear. am j phys anthropol 80:447-460. teaford mf, walker, a. 1984. quantitative differences in dental microwear between primate species with different diets and a comment on the presumed diet of sivapithecus. am j phys anthropol 88:347-364. teaford mf, maas mc, simons e. 1996. dental microwear and microstructure in early oligocene primates form the fayum, egypt: implications for diet. am j phys anthropol 101:527-543. ungar ps. 2000. microware 4.0. lukacs 2009.5 30 dental perspectives on human evolution: stateof-the-art research in dental paleoanthropology. 2007. edited by shara e. bailey and jean-jacques hublin. vertebrate paleobiology and paleoanthropology series. dordrecht, the netherlands: springer (403 pages + index). $129.00, isbn: 978-1-4020-5844-8 this is the third book in springer’s series on vertebrate paleobiology and paleoanthropology; it consists of the proceedings of the first symposium on human evolution held at the max planck institute for evolutionary anthropology (leipzig, germany). the volume illustrates the diverse and innovative ways that teeth inform our understanding of human evolution. recent advances in the analysis of dental morphology, microstructure, development, and wear are showcased with respect to how they have increased knowledge of hominin phylogeny, ontogeny, and adaptation to changing dietary environments. an introduction to the volume by simon hillson provides a synopsis of key themes and unique perspectives presented in each chapter. the four main sections of the volume begin with an introductory chapter by scholars that have made a significant impact on the field. these introductions provide useful analytical summaries of each contribution and place them in the broader context of research in dental anthropology and paleoanthropology. some, such as fred grine’s introduction to part iv: ‘dentition and diet’, which focuses on dental macroand micro-wear, is comprehensive, historical, and well referenced with 135 citations. others, including wood’s introduction to part iii: ‘dental development’ are brief, yet highlight key features of each chapter in the section. a bit perplexing is macchiarelli and bailey’s introduction to part ii: ‘dental microstructure and life history’, where on several occasions the reader is uncertain which author ’s observations and opinions are being presented (‘in my view’, ‘i would also like to note’, ‘in my personal view’). a brief synopsis of each of four section of the volume follows. part i: ‘dental evolution and dental morphology’, contains seven chapters, and begins with pilbrow’s analysis of occlusal odontometric variation in great ape molar teeth. results indicate that great ape molar metrics exhibit patterns of inter-species and sub-species taxonomic diversity. despite small sample sizes, lack of understanding of inter-trait associations, and use of a classification system designed for scoring modern human tooth crown morphology, bailey and wood explore the evolutionary divergence of the homo and paranthropus lineages using post-canine morphometric variation. they find that increased dental crown complexity in paranthropus is not a primitive retention and that dental trends said to be characteristic of homo actually appear relatively late in human evolution. maxillary molar cusp morphology of south african australopithecines is analyzed by moggi-cecchi and boccone who find similarities (in crown base areas) and significant differences (in relative area of anterior cusps and molar size sequences) between a. africanus and a. robustus. crown morphology of fossil samples from gran dolina (td-6) and sima de los huesos are used by martinón-torres and colleagues, to assess phylogenetic issues related to the early colonization of europe. they conclude that a coordinated assessment using biological and cultural evidence holds promise. an innovative technique—neural network analysis using self organizing maps—for describing dental morphology is used by manni and colleagues to evaluate the relationship between archaic and modern homo sapiens. though it has some advantages, this new technique may have limitations that preclude its adoption by other investigators. the final two chapters in part i focus on exciting new, non-destructive advances in imaging dental structures and tissues. olejniczak and associates discuss methodological aspects of 3d data acquisition by micro-computed tomography of primate molar teeth. precise and reliable portrayal of the enamel-dentine junction and measures of enamel cap thickness are tightly linked to methodological parameters such as slice thickness and pixel resolution. the advantages of high resolution x-ray computer tomography (hrxct) for obtaining digital 3d data and volumetric properties of dense tissues, is reviewed by gantt and colleagues. five chapters comprise part ii: ‘dental microstructure and life history.’ this section begins with an analysis of dental microstructure, growth and life history of megaladapis, providing estimates of gestation length, molar crown initiation, formation and completion times and minimum emergence ages for m1 and m2. schwartz and colleagues find that molar development is rapid and poorly explained as a function of adult body mass. microstructural indicators of dental development in a single female specimen of pan paniscus are described by ramirezrozzi and lacruz. preliminary results from the analysis of perikymata and striae counts reveal high appositional rates and short crown formation time for i1 while molar crown formation time is similar to that of the common chimpanzee. new data on chimpanzee and human molar crown development are presented by tanya smith and associates, who document variation in incremental features within and between genera. within cusp types humans show greater average cusp formation times than chimpanzees due either to thicker cuspal enamel and/or higher mean periodicity values. high variability in cusp formation times and overlapping ranges raise concerns for interpreting small samples. enamel microstructure of australopithecus africanus book reviews 31 is documented by bromage and colleagues, who employed a portable confocal scanning optical microscope to circumvent analytic issues such as limited magnification and specimen preparation. crossstriation periodicity and data on striae-edj angles are presented and crown formation time for a single molar (stw 284, m2) is estimated at between 3.0 and 3.2 years. in the final paper in this section, guatelli-steinberg and associates compare imbricational enamel growth in the anterior teeth of neandertals and three modern human groups from diverse eco-geographic settings. while no significant difference was found in imbricational enamel formation times for anterior teeth, differences were evident in the shape of growth curves (from cusp tip to cervix) and in mean perikymata numbers across anterior tooth types. part iii is devoted to ‘dental development’ and consists of four chapters spanning dental genetics and tooth size, dental development sequences, inter-group variation in calcification stages and new methods for reconstructing dental ontogeny. tooth size variation in outbred pedigreed populations of baboons and mice were used by hlusko and mahaney to test expectations derived from dental field theory. in mice, incisor size appears to be genetically independent of molar size, and circumstantial evidence from fossils suggests that some level of independence exists in the expression of anterior and post-canine tooth size in primates. braga and heuze introduce the concept of modularity to assess interactions between inter-dependent elements in growing dentitions. they observe considerably greater plasticity and variability in development timing of incisors than of other teeth and advise caution in using incisor teeth as a reliable substitute for other permanent teeth in the interpretation of fossils. preliminary results from an on-going analysis of permanent molar calcification stages (m1 and m2) in african-american and european-american children are presented by monge and associates, who find evidence of earlier maturation among children born in the 1990s. a re-evaluation of what constitutes ‘normal’ dental development and greater appreciation for the range of plasticity in dental calcification is encouraged. serial micro-ct scans are used by smith and colleagues to reconstruct the topography of the dento-enamel junction and quantify cusp volume and relationships during successive stages of development. this research suggests that spatial relationships consist of shape differences that are established early in morphogenesis by differential development within the tooth germ, and that differences in cusp size and proportions are modified at the crown surface by enamel apposition. dental wear and elemental ratios in fossil hominin and modern human teeth are addressed by five diverse contributions to part iv, entitled ‘dentition and diet”. an innovative method known as laser ablation inductively coupled plasma mass spectrometry (laicp-ms) was used by humphrey and colleagues to determine changes in sr/ca ratios across the neonatal line in deciduous teeth of formula-fed and breastfed children. marked reduction in sr/ca ratios were detected across the neonatal line in breast-fed children but not in formula-fed children, a result that holds promise for interpreting the chronology of dietary transitions in infancy and early childhood. tooth crown topography, a landmark-free, 3d method of describing crown morphology, is employed by ungar to show that differences in diet can be inferred from worn teeth in extant apes, that species-specific wear patterns allow inferences of function from form in worn teeth, and that differences in molar crown topography in paranthropus and australopithecus suggest differences in diet and fallback foods. a retrospective review of past accomplishments and vision of future developments in the field of dental microwear is provided by teaford, who regards ‘low magnification’ methods and scale-sensitive fractal analysis as ‘next steps’ in this rapidly developing field. ulhaas and colleagues employ 3-d analysis of occlusal surface wear to comparatively assess variation in three hominin taxa: a. afarensis, a. africanus, and paranthropus robustus. using a portable optical triangulation scanner, inter-specific differences in the mode of reduction in occlusal relief was responsible for enhancing variation in wear facet orientation, an observation that implies low levels of interspecies competition for food. in the final chapter of the book, estebaranz and associates use micrographs (sem) and 3-d topographic images of molar buccal surfaces to characterize striation density and enamel surface roughness in three extant and three fossil hominin taxa. postmortem surface damage and automated data acquisition were considered in this study which found a clear and significant association between some measures of enamel roughness and microwear pattern, a finding of value in inferring diet. overall, i found the volume a valuable review of emerging methods and new approaches to the use of dental morphology, microstructure, development, and wear in unraveling critical issues in human evolution. the hominin focus of the volume, made some chapters (part ii, chapter 2: lemur dental development; part iii, chapter 2: quantitative genetics of mice and monkeys) seem either out-of-place, or a refreshing departure from the main theme. the book is top-heavy with introductions (to the volume and then again to each individual section), yet lacking in summary, synthetic or integrative perspectives either by section, or for volume as a whole. this is an unfortunate omission. though diverse in their objectives and methods, the contributions to this volume exhibit significant overlap in the questions posed and the results derived. a book reviews 32 comparative assessment of contributions, followed by a summary of the issues and themes that were consistently affirmed, as well as those on which divergent interpretations exist, would have been a valuable service to the reader. as with many edited volumes, contributions are variable though in different ways; some chapters fail to yield definitive conclusions due to limitations of either sample size or methodology or both; while others present innovative and potentially useful analytical methods that suffer from operational complexity limiting their adoption by other investigators. finally, it’s sad that a volume devoted to cuttingedge technology contains so many annoying errors. for example, some text citations are missing from the references in the introduction to part i (page 5, martintorres et al., 2007; and kono, 2004). elsewhere (part i, chapter 5), text references to illustrations are incorrect: a) on page 70, in discussing lower second premolar morphology, the reader is referred to figure 3, which illustrates lower second molar occlusal surfaces. again on page 73, in discussing molar cusp number, the book reviews daa subscription the secretary-treasurer of the dental anthropology association is dr. loren r. lease of youngstown state university. dr. loren r. lease department of sociology and anthropology youngstown state university one university plaza youngstown, ohio 44555 usa telephone: (330) 941-1686 e-mail: lrlease@ysu.edu dental anthropology now is published electronically and e-mailed to all members as a pdf. the pdf is published with color illustrations, though the printed version is in black-and-white. if you also want to receive a hard copy, be sure to make this clear on the membership form at the daa website or contact loren. speed communication about your membership by contacting loren directly (other officers may not have current membership lists). electronic versions (as pdf files) of the back issues of dental anthropology are available gratis at the association’s web site that is maintained at the ohio state university: the web site’s home page is: http://anthropology.osu.edu/daa/index.htm reader is referred to figure 5 which illustrates lower first premolar teeth. sloppy editing, or inept use of the spell-checker, results in some awkward sentences; for example, on page 188, we read “... when discussing variation in enamel developmental, ...” and “in light if this, ...”, and page 189, “... if is unclear why this population ....” researchers, teachers and graduate students in human and dental evolution, and possibly in allied clinical fields, will find the volume an indispensable and essential aid in keeping abreast of current developments in dental anthropology. however, given the rapid rate of change in method and theory in dental paleoanthropology, i’m concerned about the shelf-life of books devoted to cutting-edge issues and technology that require a significant financial investment. john r. lukacs department of anthropology university of oregon, eugene, oregon.e-mail: jrlukacs@oregon. uoregon.edu hemphill 2013.3 16 a fool’s mission? a test of three common assumptions in dental metric analyses brian e. hemphill department of anthropology, 405a bunnell hall, university of alaska, fairbanks, fairbanks, ak 99775-7720 keywords: morphogenetic fields, ontogenetic canalization, sex dimorphism abstract three aspects of metric variation in the permanent dentition of humans are often simply accepted as true. the first is that formation of the permanent dentition occurs within morphogenetic fields broadly associated with tooth type and jaw. the second is that dental development of among females is characterized by a higher degree of ontogenetic buffering relative to males. the third is that expression of sex dimorphism in permanent tooth size is expressed uniformly among wellnourished human populations. this study tests these assumptions through an examination of mesiodistal and buccolingual dimensions of all non-canine permanent teeth, except third molars, among 2,709 living individuals of 15 ethnic groups from south asia. with sexes pooled, only one in four contrasts of variance among key versus distal teeth within dental fields are significantly heterogeneous, while one in four contrasts yield higher levels of variance among key teeth relative to their distal counterparts within a dental field. such results weaken considerably orthodox applications of butler’s dental field theory. when samples are the unit of analysis, male samples are marked by fewer dental fields with significantly heterogeneous levels of variance between key and distal members, while males and females are affected equally by significantly heterogeneous variation between key and distal members when dental fields are the unit of analysis. such results suggest males and females are equally buffered against environmental perturbations that affect odontometric variation. one-way anova indicates that a tooth’s position within a dental field accounts for 15.5% to 23.1% of the observed variation in tooth size, while two-way anova reveals that when sex is added as a second factor, the percentage of variance in tooth size explained increases from 16.7% to 30.8%, an improvement of 27.2%. such results indicate sex dimorphism in tooth size varies in both patterning and in magnitude among these samples, thereby explaining why discriminant functions developed for one population often perform more poorly when applied to other populations. over the last 70 years a consensus has emerged that dental development in humans is characterized by a series of developmental fields that correspond broadly to tooth type by jaw (butler 1939; dahlberg 1945, 1951), that odontogenesis is marked by a greater degree of developmental buffering, or “canalization,” among females relative to males (garn et al. 1965, 1966; nichol et al. 1984; niswander & chung 1965), and that expression of sex dimorphism is uniformly expressed across adequately nourished human populations (kieser et al. 1985). this study tests these assumptions through assessment of mesiodistal and buccolingual dimensions of all noncanine permanent teeth except third molars among 2,709 living individuals of 15 ethnic groups from south asia. materials and methods dental casts were collected from 2,709 living individuals with informed consent of 15 ethnic groups from the hindu kush/karakoram highlands of northern pakistan, the northern periphery of the indus valley of pakistan, gujarat state of northwestern peninsular india, and andhra pradesh state of southeastern india (fig. 1). of these, some 2,455 individuals (1,087 females, 1,368 males) are represented by casts for both upper and lower dentitions. mesiodistal tooth lengths and buccolingual tooth breadths were measured for all teeth, except third molars using standard odentometric procedures (moorrees, 1957). kolmogorov-smirnov tests were used to determine whether correspondence to: brian hemphill, department of anthropology, 405a bunnell hall university of alaska, fairbanks, ak 99775-7720 bhemphill@alaska.edu 17 variable distributions by sex and by sample depart significantly from normality. antemortem tooth loss, dental pathology and casting defects preclude some measurements from being collected. em estimation (dempster et al., 1977) was used to estimate missing values by sex and by sample. no more than three of the 28 variables (10.7%) were estimated by individual. teeth within incisor, premolar and molar dental fields were separated into “key” and “distal” members by jaw. standard descriptive statistics were calculated for each variable. heterogeneity of variance between key and distal members was tested with bartlett’s chisquare (snedecor and cochran, 1989) and variances were compared to test for the expected pattern of higher variance for the distal member within each morphogenetic field, except for the mandibular incisors for which dahlberg (1945, 1951) maintained that the morphogenetic field was reversed, such that li2 is considered the key tooth and li1 the distal tooth. one-way anova was used to test for the impact of position within a dental field upon tooth size in both sex-pooled and sex-segregated samples by ethnic group. sexpooled samples were further tested with two-way anova to determine the impacts of position and sex by ethnic group. relative contributions of sex to position were rank ordered to illustrate differences between samples in the expression of sex dimorphism. results kolmogorov-smirnov tests reveal that mesiodistal lengths and buccolingual breadths for males and females of all 15 samples are distributed normally. of the 2,455 individuals represented by fig. 1. location of the samples used in the study. abbreviations are from table 1. 18 t a b l e 1 . s a m p le s u se d i n t h e s tu d y r e g io n 1 a b b . g ro u p l o c a li ty r a w _ n f e m a le s m a le s n e n e /r a w _ n n p c t. n p c t. n p c t. n p c t. n iv p a w a m a w a n m a n se h ra 1 7 2 4 0 1 1 0 1 5 0 8 7 .2 1 9 1 2 .7 4 7 3 1 .3 7 1 4 7 .3 1 0 7 7 1 .3 n iv p s w t m s w a ti m a n se h ra 2 1 5 6 8 1 0 3 1 7 1 7 9 .5 3 5 2 0 .5 6 3 3 6 .8 9 3 5 4 .4 1 1 8 6 9 .0 h k b lt 0 1 b a lti p a rt u k 1 8 4 8 0 7 6 1 5 6 8 4 .8 2 8 1 7 .9 5 3 3 4 .0 8 4 5 3 .8 1 1 9 7 6 .3 h k m d k m a d a k la m a d a k la sh t 1 9 2 9 4 8 0 1 7 4 9 0 .6 7 0 4 0 .2 1 0 2 5 8 .6 1 3 1 7 5 .3 1 4 7 8 4 .5 h k s h ia s h in a a st o re 1 6 4 5 9 8 3 1 4 2 8 6 .6 7 8 5 4 .9 9 2 6 4 .8 1 1 5 8 1 .0 1 1 9 8 3 .8 h k s h ig s h in a g il g it 1 0 6 5 4 5 0 1 0 4 9 8 .1 8 3 7 9 .8 8 6 8 2 .7 9 5 9 1 .3 9 8 9 4 .2 h k w a k g w a k h i g u lm it 1 4 9 6 2 5 7 1 1 9 7 9 .9 5 9 4 9 .6 7 3 6 1 .3 9 2 7 7 .3 9 8 8 2 .4 h k w a k s w a k h i s o st 1 9 0 6 7 7 2 1 3 9 7 3 .2 6 1 4 3 .9 7 3 5 2 .5 9 8 7 0 .5 1 0 6 7 6 .3 h k y a s a y a sh k u n a st o re 1 7 5 6 4 8 1 1 4 5 8 2 .9 4 3 2 9 .7 6 6 4 5 .5 9 4 6 4 .8 1 1 0 7 5 .9 s e c h u c h e n ch u a n d h ra p ra 1 9 6 8 6 1 0 9 1 9 5 9 9 .5 1 2 9 6 6 .2 1 5 8 8 1 .0 1 7 8 9 1 .3 1 8 7 9 5 .9 s e g p d m a d ig a a n d h ra p ra 1 7 7 7 8 9 6 1 7 4 9 8 .3 8 2 4 7 .1 1 3 1 7 5 .3 1 5 5 8 9 .1 1 6 2 9 3 .1 s e p n t p a k a n a ti a n d h ra p ra 1 8 4 8 2 9 9 1 8 1 9 8 .4 1 0 9 6 0 .2 1 4 5 8 0 .1 1 6 6 9 1 .7 1 7 0 9 3 .9 n w b h i b h il g u ja ra t 2 0 8 1 0 5 1 0 3 2 0 8 1 0 0 .0 1 5 2 7 3 .1 1 7 2 8 2 .7 1 8 9 9 0 .9 2 0 0 9 6 .2 n w g r s g a ra si a g u ja ra t 2 0 7 9 9 1 0 8 2 0 7 1 0 0 .0 1 3 6 6 5 .7 1 7 8 8 6 .0 1 9 0 9 1 .8 1 9 8 9 5 .7 n w r a j r a jp u t g u ja ra t 1 9 0 4 9 1 4 1 1 9 0 1 0 0 .0 1 1 4 6 0 .0 1 5 6 8 2 .1 1 7 2 9 0 .5 1 8 9 9 9 .5 t o t a l 1 1 6 2 4 9 9 6 5 6 1 1 5 5 9 9 .4 1 1 9 8 4 8 .8 1 5 9 5 6 5 .0 1 9 2 3 7 8 .3 2 1 2 8 8 6 .7 1 . r e g io n a b b re vi a ti o n s a re a s fo ll o w s: n iv p ( n o rt h e rn i n d u s v a ll e y p o p u la ti o n s) , h k ( h in d u k u sh h ig h la n d s) , s e ( s o u th e a st e rn p e n in su la r in d ia ), n w (n o rt h w e st e rn p e n in su la r in d ia ). 19 casts for both dentitions only 1,198 (48.8%) are represented by all 28 variables. estimation of missing values improved the number of individuals with complete data from 1,595 (65.0%), to 1,923 (78.3%), to 2,128 (86.7%) when 1, 2, and 3 variables were estimated, respectively (table 1). bartlett’s chi-square reveals that just over onefourth (47/180= 26.11%) of contrasts of variance between key and distal members of a dental field exhibit significant heterogeneity of variance. the number of significant differences by sample averages 3.13 out of the 12 fields (26.08%) and ranges from a high of six fields among awans and garasias to a low of zero among the yashkuns of astore. when instances of significant heterogeneity of variance within dental fields are examined to determine whether this heterogeneity is driven by higher variance in key teeth versus higher variances in distal teeth, expectations of dental field theory are resoundingly confirmed. as expected, the vast majority (42/47= 89.36%) of cases involve higher variance for the distal member of a dental field (fig. 2). in fact, instances of significantly higher variances among key teeth occur among members of only three of the ethnic groups considered here. these include awans, bhils, and rajputs. a situation in which the amount of variance among key members of a dental field exceed that found among their distal counterparts represents a reversal of dental field theory expectations. examination of levels of variance reveals some 46 instances of reversal, accounting for just over onefourth of all comparisons (46/180= 25.56%). the number of reversals runs from a high of seven (58.33%) among shinas from gilgit (shig) to lows of a single reversal among garasias (grs) and gompadhomptis madigas (gpd) (fig. 3). further examination indicates that while all non-canine dental fields of both jaws are affected, reversals are by far most common among the mandibular incisors (li2>li1) where two-thirds of all contrasts yielded reversals (20/30= 66.7%). reversals are also common among mandibular molars (9/30= 30.0%), are less common among maxillary incisors (6/30= 20.0%) as well as among mandibular (5/30= 16.67%) and maxillary premolars (5/30= 16.67%), and are rarest among maxillary molars (1/30= 3.33%). analysis of variance indicates that position within a dental field contributes substantially to the percentage of variance explained in tooth size (fig. 4). across all 15 samples position alone accounts for nearly 20% of the variance in tooth size within a dental field, ranging from highs of 23.08% and 22.92% among bhils and chenchus to a low of 15.47% among the wakhis of gulmit. bartlett’s chi-square (fig. 5) reveals that males are marked by a fewer number of dental fields with significantly heterogeneous levels of variance fig. 2. number of significant differences in variance between key and distal members of a dental field by position with sexes pooled. 20 between key and distal member, for significant heterogeneity occurs in only three of the 15 samples (20.0%), while females are marked by equivalent or higher numbers of reversals in 12 of the 15 samples (80.0%). when heterogeneity of variance is considered by dental field across all samples, bartlett’s chi-square identifies 68 of 360 (18.89%) contrasts as exhibiting significantly heterogeneous levels of variance. of these, 35 occur among males and 33 occur among females, indicating that males and females are marked by nearly identical numbers of significantly heterogeneous contrasts with regard to variance. examination of the patterning of variance among key and distal teeth within dental fields reveals that somewhat more than one-fourth (99/360= 27.5%) are marked by a reversal in which variance is greater among key teeth than their distal counterparts (fig. 6). when considered by sex, males are more often affected by reversals (31.11%) than females (23.89%). in fact, males exhibit a marked increase (30.23%) relative to that observed among females. when considered by sample, reversal prevalence is greater among males for only six of the 15 samples. this means that, contrary to expectations, males more often exhibit variance reversals than females overall, while in marginal support of expectations, females have a higher or equivalent number of dental fields marked by variance reversals than males in nine (60%) of the 15 samples. analysis of variance has already indicated that a tooth’s position within a dental field accounts for 15.5% to 23.1% of the variance in size across the 15 samples (fig. 4). when this relationship is further explored by sex it is clear the influence of sex on the relative size of key and distal members within dental fields differs markedly (fig. 7). in 11 samples, the average contribution of position is greater among females, while in the remaining four the contribution is greater among males. in some samples, such as the awans (4.82%) swatis (6.3%) and baltis (4.74%) this difference is well-marked, but in others, such as the bhils (0.01%), the greater contribution of position among females is minimal. in fact, the opposite pattern may also be discerned, where among some samples the difference between the sexes is well-marked, but is greater among males than females, such as among the wakhis of gulmit (5.3%), or is but minimal as is the case for pakanatis (0.14%). such findings indicate that sex contributes substantially, but differently by sample, to relative tooth size between key and distal members of the same morphogenetic field. fig 3. number of reversals in relative variance between key and distal members of a dental field with sexes pooled. 21 as noted above, one-way anova has already demonstrated that a tooth’s position within a fig. 4. average contribution by position in accounting for variance in tooth size between key and distal members of a dental field with sexes pooled. fig. 5. number of dental fields in which there are significantly different levels of variance between the key and distal member. 22 fig. 6. number of dental fields in which there is a reversal in the amount of variance expressed by key and distal members. dental field contributes substantially (15.5%23.1%) to the determination of tooth size (fig. 4), but when considered by sex across the 15 samples it is also clear this contribution differs markedly in both magnitude and polarity (fig. 7). a two-way analysis of variance by sample indicates that when sex is added as a second factor, the percentage of variance explained increases between 16.7 to 30.8%, an improvement of 27.2% over when position is considered alone. the improvement in accounting for the variance in tooth size between key and distal members of a dental field varies widely, from a low of 0.6% among awans, to a high of 13.2% among wakhis from sost. nevertheless, a paired-samples t-test indicates this improvement is statistically significant (t= 2.764; p= 0.015). clearly, then, sex, in addition to position, is influential in the determination of relative tooth size between key and distal members within a dental field. however, that influence appears to differ markedly across samples. rank ordering is used to illustrate differences among samples in the relative contributions played by sex and by position in the relative size of key and distal members of the same morphogenetic field. ranks were assigned such that those variables in which sex provides a relatively great contribution to the determination of relative size receive high ranks, while those variables in which sex plays a relatively lesser role receive low ranks. ranks are plotted for maxillary variables in figure 8, while ranks are plotted for mandibular variables in figure 9. two-way anova reveals that the contribution of sex to relative tooth size of key and distal members of dental fields is greatest for the buccolingual breadths of the premolars and molars in the maxillary dentition, as well as the buccolingual breadths of the incisors and mesiodistal lengths of the premolars in the mandibular dentition. by contrast, the contribution of sex is low for the mesiodistal lengths of both maxillary and mandibular incisors. nevertheless, despite these overall trends, there is considerable variation among the 15 samples in the contribution of sex for the remaining variables. indeed, variation in the relative contribution of sex appears especially wellmarked for buccolingual breadths of incisors and mesiodistal lengths of premolars in the maxillary dentition, as well as the buccolingual breadths of the incisors and premolars in the mandibular dentition. 23 fig 7. average contribution by position in accounting for variance in tooth size between key and distal members of a dental field by sex. fig 8. average relative contribution of sex to position in determination of relative tooth size between key and distal maxillary teeth within a dental field by rank order (ranked by contribution from sex). 24 when considered by jaw, variation in the contribution of sex to relative tooth size of key and distal members of the same morphogenetic field among the maxillary teeth varies most among the 15 samples for the mesiodistal lengths of the premolars (sd= 2.274), followed by the buccolingual breadths of the premolars (sd= 1.988) and incisors (sd= 1.397). by contrast, variation in rank order is rather low for the mesiodistal lengths (sd= 1.223) and buccolingual breadths (sd= 1.060) of the molars, while variation among samples is lowest of all for the mesiodistal lengths of the incisors (sd= 0.743). looked at another way, the rank order score for the relative contribution by sex to position for mesiodistal dimension differences between the key and distal members of this morphogenetic field ranges from one among the awans (where sex contributes the most among the 12 variables considered) to 10 among the wakhis of gulmit (where the sex contributes third lowest among the 12 variables considered). turning to the mandibular teeth, variation in the contribution of sex to relative tooth size of key and distal members of the same morphogenetic field among the mandibular teeth varies most among the 15 samples for the buccolingual breadths of the premolars (sd= 2.000), followed by the buccolingual breadths of the incisors (sd= 1.668) and the mesiodistal lengths of the molars (sd= 1.624). variation in rank order is rather low for the buccolingual breadths of the molars (sd= 1.397) and the mesiodistal lengths of the premolars (sd= 1.187), while as in the maxillary arcade, variation is lowest for the mesiodistal lengths of the incisors (sd= 1.183). when the dispersion in rank order scores across samples is considered, the relative sex contribution versus the contribution by position for differences in buccolingual breadths between the key and distal members of the premolars ranges from two among the two wakhi samples (wakg, waks) to a high of nine among chenchu tribals of southeastern peninsular india. by contrast, dispersion in mesiodistal lengths of the incisors only ranges from one in three samples (chu, gpd, shig) to five (wakg). discussion question 1: do developmental fields exist such that variance is less among “key” teeth relative to “distal” teeth? it has often been maintained that the earlier developing members within a morphogenetic field are less affected by environmental factors than later developing members (alvesalo and tigerstedt, 1974; townsend and brown, 1980) and this has led some researchers who focus on dental morphology to limit considerations of differential trait frequencies found on key teeth only (scott and dahlberg 1982; scott et al 1983; sofaer et al 1972; turner 1976). a recent review by townsend and co-workers (2009) observes that later developing teeth within a morphogenetic field spend a relatively longer period of time in the soft tissue stage prior to calcification during which epigenetic and environmental factors can influence the shape and size of the crown. a similar observation was made by keene (1982), whose concept of the morphogenetic triangle emphasized the dynamism in the formation of the individual cusps until coalescence among the cusps fuses them in place. not surprisingly, given these expectations, it has been widely assumed that the key tooth within each morphogenetic field ought to possess the highest heritabilities, while the non-key teeth ought to be marked by lower heritabilities. indeed, alvesalo and tigerstadt (1974) reported such patterning in their data, but other researchers have been unable to confirm such results (dempsey and townsend, 2001). with sexes pooled, only one out of four contrasts of variance between key and distal members within dental fields are significantly heterogeneous, but the overwhelming majority that are significant are due to much higher variance among distal members. while such findings corroborate dental field theory and the findings of other researchers (harris & nweeia 1980; herskovitz et al. 1993; kieser & groeneveld 1998; mayhall & saunders 1986), it is also the case that one in four contrasts yields higher variance for the key tooth than for the distal tooth within a dental field. a large number of these reversals occur among the mandibular incisors, suggesting that dahlberg’s (1945, 1951) insistence on a reversal of the dental field among mandibular incisors is incorrect. in contrast to expectations of the theory of compensatory tooth size effect (sofaer 1973; sofaer et al, 1972a,b), as well as the findings of some researchers with regard to bilateral asymmetry (harris & nweeia 1980; townsend & brown 1980), no predilection for increased variance was found for mesiodistal 25 over buccolingual dimensions or vice versa. indeed, one-way anova indicates that position within a dental field only contributes about onefifth of the percentage of variance explained in tooth size. taken together, such results weaken considerably an orthodox application of butler’s field theory. as noted by townsend et al. (2009), a complicated array of epigenetic and morphogenetic events appears to be involved at different times and to various degrees in crown formation. further, given more recent research which indicates that secondary enamel knot formation determines the location of cusp tips (jernvall et al., 1994; matalova et al., 2005), that knot positioning relative to the margin of the occlusal surface (moorman et al., 2013) and overall crown size are related to such morphological features of the permanent tooth crown as carabelli’s trait (harris, 2007), it is clear that crown size and shape are phenomena whose interrelatedness are poorly captured by simplistic developmental models that rely upon morphogenetic fields with key and distal members. question 2: are females more genetically canalized than males? the assertion that among humans males are less buffered against environmental stress than females can be traced to greulich’s (1951) study of growth and development among children on the island of guam who suffered from nutritional stress and other deprivations during world war ii. greulich found than guamanian boys suffered greater shortfalls in height, weight, weight for height and skeletal maturation than girls when compared to well-nourished u.s. children. similar results were found among children who survived the atomic bombing of hiroshima and nagasaki (gruelich et al., 1953), as well as children exposed to radiation caused by nuclear testing in the marshall islands (sutow et al., 1965). in 1969, stini examined the impacts of malnutrition upon growth and development among boys and girls of helconia, colombia. he found skeletal maturation to be delayed in all malnourished children early in life. however, skeletal age among girls was closer to u.s. standards in the earliest years of life and the differences in skeletal maturity between boys and girls increased throughout adolescence such that girls experienced a form of “catch-up” growth to u.s. standards while similarly malnourished boys failed to do so resulting in a reduction of “blunting” of sex dimorphism (dettwyler, 1992; eveleth, 1975; leonard, 1991; stini, 1972; tobias, 1972). similar results have been obtained in studies of the impact of high altitude upon growth and development among andean populations (frisancho and baker, 1970; pawson, 1977; stinson, 1980), as well as sex differences in response to infectious diseases (stini, 1985), parasite loads (brabin, 1990), and famine (grayson, 1990). stini (1975, 1982, 1985) suggested that such sex differences may be the consequence of selection for better environmental buffering in females because of their greater investment in reproduction in supporting pregnancy, lactation and child rearing. turning to odontometric variation within the permanent dentition and given the expectations of dental field theory, males ought to express a lesser degree of genetic canalization by exhibiting greater variance among distal members of a morphogenetic field relative to key members. that is, the lesser degree of buffering against environmental perturbations ought to more often result in levels of variance among key and distal teeth that are statistically different. further, because of lesser buffering and hence greater variation among distal teeth within a morphogenetic field, reversals in levels of variance among key and distal members of the same morphogenetic field ought to be few. by contrast, among females the greater amount of buffering should reduce the relative amount of variance found among the distal members of a morphogenetic field and thereby result in fewer instances in which the levels of variance between key and distal members of a morphogenetic field are significantly heterogeneous. a secondary consequence of greater buffering among females is that greater parity in variance among key and distal members of a morphogenetic field is that reversals ought to be more common due to random chance. running contrary to expectations, bartlett’s chi-square indicates that males are marked by a fewer number of dental fields with significant heterogeneous levels of variance between key and distal members, for significant heterogeneity occurs in only three of the 15 samples (20.0%), while females are marked by equivalent or higher numbers of reversals in 12 of the 15 samples (80.0%). when heterogeneity of variance is considered by 26 dental field across all samples, bartlett’s chisquare identifies 68 contrasts as exhibiting significantly heterogeneous levels of variance. once again running contrary to expectations, males do not exhibit a pattern in which they are affected far more often than females. instead, with 35 and 33 significant differences affecting males and females, respectively, it appears that members of both sexes are equally buffered against environmental perturbations that affect odontogenesis. as noted above, an examination of the patterning of variance among key and distal teeth within dental fields finds that a little more than one-fourth (99/360= 27.5%) are marked by a reversal in which variance is greater among key teeth than their distal counterparts. males are more often affected than females, but when considered by sample, reversal prevalence is equivalent or greater among females than males in nine of the 15 samples. taken together, these results offer only tepid support for the contention that females are more highly genetically canalized and hence odontogenesis is less affected by environmental factors among females than are males. these finding corroborate those of other researchers who find similar levels of postnatal variability in growth and development among members of both sexes (frisancho et al., 1980; martorell et al., 1975, 1984; stinson, 1985; yarborough et al., 1975) as well in linear enamel hypoplasia prevalence (angel et al., 1987; goodman et al., 1987, 1991; manzi et al., 1999; may et al., 1993; santos and coimbra, 1999; zhou and corruccini, 1998). however, as noted by guatelli-steinberg and lukacs (1999), indicators of postnatal stress offer a mixed signal concerning sex differences in response to stress. this is because cultural factors may outweigh and obfuscate the actual levels of stress experienced. thus, the evidence found here for equivalent levels of variability for males and females may be the consequence of cultural factors that favor care, treatment and feeding of boys over girls. thus, with regard to greater developmental canalization of females over males, it is clear that if such canalization exists it is not of a sufficient degree to be expressed consistently across the samples analyzed here. consequently, one cannot assume that females will be less variable odontometrically than their male counterparts. question 3: is sex dimorphism uniformly expressed across adequately nourished human populations? teeth are considered a useful means for determination of sex (ghose and baghdady, 1979; harris and nweeia, 1980; potter et al., 1981; iscan and kedici, 2003), especially in cases where remains are highly fragmentary (anuthama et al., 2011; prabhu and acharya, 2009; vodanovic et al., 2006). it is usually the case that the canines are the most dimorphic teeth in the permanent dentition (acharya and mainali s., 2007; garn et al., 1967; iscan and kedici, 2003; lund and mörnstad, 1999; potter et al., 1981; townsend and brown, 1979), but some studies report that other teeth are either the most dimorphic (garn et al., 1966; shrestha, 2005) or nearly as dimorphic as the canine in certain populations (iscan and kedici, 2003; kieser and groeneveld, 1989; perzigian, 1976; potter 1972; potter et al., 1981; sharma 1983). indeed, some studies have reported the presence of “reverse dimorphism” in which females possess larger averages for certain variables than males (acharya and mainali, 2007; ghose and baghdady, 1979; harris and nweeia, 1980; prabhu and acharya, 2009). in fact, ghose and baghdady (1979) report that fully one-third of the variables they examined among yemenites exhibit such “reverse dimorphism.” numerous studies report population differences in both the patterning (anuthama et al., 2011; ates et al., 2006; iscan and kedici, 2003; prabhu and acharya, 2009) and magnitude (anuthama et al., 2011; iscan and kedici, 2003; prabhu and acharya, 2009) of sex dimorphism in odontometric variables. such differences also extend to the relative size of key versus distal members of the same morphogenetic field. designating such differences as “tooth size crown gradients,” harris and harris (2007) found marked differences between major human groups in which some are marked by “steep” gradients of sharp reductions in size from the key to distal teeth, while others possess “shallow” gradients with similar dimensions across the members of a field. one-way anova demonstrated that among the 15 samples considered here a tooth’s position within a dental field accounts for 15.5% to 23.1% of the observed variation in tooth size within morphogenetic fields. yet, it is also the case that when 27 variation within dental fields is considered by sex it is clear the contribution from sex differs markedly with regard to both magnitude and polarity. a two-way analysis of variance by sample revealed that when sex is added as a second factor, the percentage of variance explained increases to 16.7%30.8%, which is an improvement of 27.2% when consideration is limited to position within a morphogenetic field. in accordance with the observations of harris and harris (2007), the improvement in accounting for the variance in tooth size between key and distal members of a dental field varies widely. thus, not only does it appear that sex, in addition to position, is influential in the determination of relative tooth size between key and distal members within a dental field, it is also the case that this influence differs markedly across samples. such differences in the expression of sex dimorphism were found to mirror differences in tooth size allocation as a whole (hemphill, 1991) and also explain why discriminant functions developed for determination of sex in one population often predict sex with much lower accuracy when applied to members of other populations (wright and hemphill, 2012). conclusion viewed as a whole, this “fool’s mission” appears not to have been at all foolish. dental field theory offers an inaccurate picture of the true pattern of variation among key and distal members of morphogenetic fields. for while it is the case that key teeth are often less variable than their distal counterparts, reversals are common. dahlberg’s (1945, 1951) alleged reversal of polarity among mandibular incisors is not supported, nor is sofaer’s (1973; sofaer et al, 1972a,b) notion of compensatory tooth size effect. the notion that females tend to be more highly genetically canalized than males and hence are more resistant to environmental perturbations is not confirmed. males and females were found to exhibit similar levels of relative variability between key and distal members of morphogenetic fields. however, since much of the development of the permanent tooth crown occurs post-natally, potential mitigating cultural factors that favor males over females cannot be ruled out. there is abundant evidence that sex dimorphism is expressed differently, both with regard to patterning and to magnitude across hufig 9. average relative contribution of sex to position in determination of relative tooth size between key and distal mandibular teeth within a dental field by rank order (ranked by contribution from sex). 28 man populations. drawing from harris and harris’ (2007) notion of tooth crown size gradients within morphogenetic fields it is clear that among the south asian ethnic groups considered here, there is considerable variation in the expression of sex dimorphism. indeed, the very low expression of sex dimorphism among the relatively wellnourished awans of mansehra district coupled with the marked expression of sex dimorphism among the isolated high altitude wakhis of sost, suggest strongly that these differences cannot be attributed to mere environmentally induced “blunting” of sex dimorphism. instead, these differences in the degree and patterning of sex dimorphism in permanent tooth size are the consequence of the same population-specific differences in the array of genes that control the apportionment of overall tooth size throughout the permanent dentition. given that population differences in the expression of sex dimorphism in permanent tooth size are even less likely to be subject to the impacts of natural selection than overall tooth size, patterning in the expression of sex dimorphism in permanent tooth size offers an additional avenue for unraveling the complex histories of human populations on local, regional and continental levels. literature cited acharya ab, mainali s. 2007. univariate sex dimorphism in the 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sarah e. heins 1 , gwyn d. madden 2 , mykhailo p. sokhatskyi 3 1department of religious studies and anthropology, university of wisconsin oshkosh, oshkosh, wisconsin, 54901 2department of anthropology, grand valley state university, allendale, michigan, 49401 3 borschiv regional museum, ministry of culture and arts of ukraine, borschiv, ukraine keywords: dental pathology, hunter-fisher-gatherers, mesolithic, neolithic abstract the tripolye were the first archaeological culture in ukraine to cultivate domesticated cereals, practice animal husbandry, and establish large settlements with high population densities. this cultural adaptation was much different than that of mobile hunter-fisher-gatherers of the ukrainian mesolithic/neolithic, and likely resulted in different outcomes for human health. this study compares the rates of enamel hypoplasias in a tripolye skeletal population with that of mesolithic/neolithic hunter-fisher-gatherers. a recently excavated sample of dentitions representing a minimum of 35 individuals from verteba cave was examined macroscopically for hypoplasias and was compared statistically to published rates for hunter-fisher-gatherers. the tripolye from verteba cave were found to have at least one enamel hypoplasia on 18.18% of teeth, while the hunter-fisher-gatherers have hypoplastic lesions on 1.88% of teeth. when examined at the individual level, 48.57% of the tripolye were found to have at least one hypoplasia, as compared to 12.77% of the hunter-fisher-gatherer individuals. the results indicate that the agropastoral tripolye experienced significantly more systemic stress than the hunter-fisher-gatherers. the higher stress likely relates to dietary and behavioral variables associated with the tripolye’s agropastoral economy, including heavy reliance on cereals as weaning foods and sanitary problems linked to sedentism. the tripolye were the first archaeological culture in ukraine to possess the full neolithic package of domesticated cultigens, livestock, and pottery (korvin-piotrovskiy, 2008). compared to earlier ukrainian populations, the tripolye interacted with their environment in a radically different way through their use of an agropastoral subsistence system and settlement in more sedentary villages with higher population densities. these changes likely had implications for the health of prehistoric humans living in the area of modern ukraine. the goal of this study is to assess the relative success of the tripolye cultural adaptation from a biocultural perspective. specifically, we use enamel hypoplasias to document the level of physiological stress experienced by the tripolye and compare this to earlier ukrainian mesolithic and neolithic hunter-fisher-gatherer populations. enamel hypoplasias are areas of abnormally thin enamel found on the crowns of teeth (goodman and rose, 1991). enamel hypoplasias can take the form of horizontal linear grooves, pits, or large areas of missing enamel (goodman and rose, 1990). these lesions form during the years of enamel development, from infancy to late childhood, and result from insufficient enamel production due to the disruption of enamel producing cells called ameloblasts (hillson, 1996). ameloblast disruption can be caused by a variety of factors, including malnutrition, infection, localized trauma, and congenital defects (goodman and rose, 1991). however, the rates of linear enamel hypoplasias caused by trauma and hereditary conditions are estimated to be extremely low, and therefore most of these lesions are believed to reflect physiological stress resulting from malnutrition, infection, or the synergistic interaction of both (goodman et al., 1980; winter and brook, 1975). this notion has been reinforced by studies of living populations, which have found a positive relationship between the prevalence of enamel hypoplasias and the degree of malnutrition and disease (cutress and suckling, 1982; goodman et al., 1987). as a nonspecific indicator of physiological stress, linear enamel hypoplasias are well suited to monitor the general biological well-being of prehistoric populations. bioarchaeological studies of the transition to agriculture previous bioarchaeological studies have used enamel hypoplasias to examine the impact of the transition to agriculture on the health of ancient human populations. studies from regions around the globe, including north america’s ohio river valley, illinois, india, china, egypt, the andes, correspondence to: jordan k. karsten, department of religious studies and anthropology, uw oshkosh, 800 algoma boulevard, oshkosh, wi 54901 phone: (920) 424-7307 fax: (920) 424-0882 email: karstenj@uwosh.edu 17 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 and mesoamerica, have documented increases in the prevalence of enamel hypoplasias following the adoption of agriculture (cassidy, 1984; perzigian et al., 1984; goodman et al., 1984; marquez-morfin and storey, 2007; alfonso et al., 2007; lukacs et al., 2001; pechenkina et al., 2002). for example, in their study of burials from the multicomponent site of dickson mounds, illinois, goodman et al. (1984) found the rate of enamel hypoplasias to significantly increase following the transition to agriculture. the cumulative impact of these studies has led many researchers to conclude that the transition to agriculture was detrimental to human health (larsen, 1995; 2006; cohen and armelagos, 1984; cohen and crane-kramer, 2007; armelagos et al., 1991). however, it is important to point out that some studies have found the rate of enamel hypoplasias to decline or remain unchanged following the agricultural transition (hodges, 1987; temple, 2010; danforth et al., 2007). for instance, temple (2010) found a decline in the prevalence of enamel hypoplasias following the transition to agriculture in his comparison of jomon hunter-gatherers and yayoi agriculturalists from japan. other studies have found patterns that are difficult to interpret. starling and stock (2007) observed an initial increase in the rate of enamel hypoplasias following the adoption of agriculture in egypt and nubia. interestingly, this transitional stress appeared to be short lived, as the rate of hypoplastic lesions gradually declined through time. the variable results of these studies demonstrate that our understanding of the health consequences of the transition to agriculture remains incomplete. compared to the rest of the globe, very few studies have focused on the health consequences of the transition to agriculture in prehistoric europe (meiklejohn and zvelebil, 1991). papathanasiou (2005; papathanasiou et al., 2000) documented enamel hypoplasias in neolithic skeletons from greece, and concluded the population experienced relatively low levels of systemic stress. due to a lack of mesolithic burials in the area, the rates of enamel hypoplasias among agriculturalists could not be compared to hunter-gatherers. bennike and alexandersen (2007) studied the biological impacts of the transition to agriculture in scandinavia, and found the rates of enamel hypoplasias to decline following the adoption of an agricultural economy and then increase over time. this study aims to address the general scarcity of european data on the health consequences of the transition to agriculture by analyzing relevant skeletal populations from ukraine. based on the results of previous bioarchaeological studies, we seek to test the hypothesis that the transition to agriculture was detrimental to the health of prehistoric populations living in ukraine. biocultural context ukrainian mesolithic and neolithic populations in ukrainian archaeological terminology “neolithic” is used to mark the appearance of pottery rather than the transition to agriculture as it is elsewhere in europe (jacobs, 1993). in fact, at many ukrainian neolithic sites, the presence of pottery may be limited to a few sherds, while at others pottery is not present (lillie, 1996). the ukrainian neolithic sites show continuity with earlier mesolithic sites in material culture, burial practices, and subsistence systems, and therefore, the mesolithic and neolithic sites will be discussed together here. much of what is known about the mesolithic/ neolithic period in ukraine comes from the mariupol -type cemeteries excavated in the dnieper rapids region (zvelebil and lillie, 2000; lillie, 1996; jacobs, 1993). stable isotope studies on the skeletal remains suggest that these populations consumed diets rich in fish and terrestrial animals (lillie and richards, 2000; lillie and jacobs, 2006; lillie et al., 2011; lillie and budd, 2011). the consumption of a diet rich in protein and low in carbohydrates is further supported by analysis of dental pathology in these skeletal samples, which have been found to be universally free of dental caries (lillie, 1996). the ephemeral nature of the mesolithic/neolithic settlements in the area, a lack of domesticated cultigens in the archaeological record, and the appearance of only a limited number of domesticated fauna at the end of the neolithic have led researchers to conclude that these populations were fairly mobile hunter-fisher-gatherers (lillie, 1996; zvelebil and lillie, 2000). in his examination of dental pathology in the mesolithic/neolithic populations from the dnieper rapids region, lillie (1996) documents and interprets the occurrence of enamel hypoplasias. he found enamel hypoplasias throughout the sample, although at a relatively low prevalence. specifically, lillie observed at least one enamel hypoplasia on 16.66% of mesolithic individuals and 11.42% of neolithic individuals for a pooled rate of 12.77%. when examined by teeth, lillie found 1.22% of mesolithic teeth and 2.25% of neolithic teeth to have one or more hypoplasias. according to lillie, the rates of enamel hypoplasias indicate suboptimal levels of subadult health during the mesolithic/neolithic period, but the low 18 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 frequencies do not indicate severe systemic stress, suggesting a generally healthy existence for the mesolithic/neolithic ukrainian hunter-fisher-gatherers. tripolye the tripolye were an eneolithic people that existed between 4800-2900 cal bc on territory that now corresponds to the modern nations of ukraine, moldova, and romania (zbenovich, 1996; rassamakin, 2012). in ukraine, the czech republic, and slovakia, the eneolithic is defined as beginning with the appearance of copper artifacts and the onset of copper metallurgy and ends with the start of the bronze age (milisauskas, 2011). the tripolye culture occupied an area stretching from the carpathian piedmont in the west, to the dnieper river in the east, and extended as far south as the black sea and as far north as kiev (videiko, 2004). the term tripolye is derived from the name of the ukrainian village near the first discovery of tripolye material culture in 1896 by v. khvoika (nikitin et al., 2010). tripolye cultural remains were independently discovered in romania, and are known there as cucuteni (lillie, 2008). consequently, publications referring to the tripolye culture also use the terms tripolye-cucuteni or cucuteni-tripolye to recognize their unity (e.g. zvelebil and dolukhanov, 1991). detailed relative and absolute chronologies have been developed that divide the existence of the tripolye into a number of different phases, including the tripolye a (4900-4300 calbc), tripolye bi (43004100 calbc), tripolye bii (4100-3600 calbc), tripolye ci (3600-3200 calbc,) and tripolye cii (3400-2750 calbc) (nikitin et al., 2010; videiko, 2004). these different phases are associated changes in pottery manufacture and decoration (ryzhov, 2012). paleobotanical evidence indicates that the tripolye cultivated a wide variety of domesticated crops including the hulled wheat types of emmer, einkorn, and spelt, hulled and non-hulled barley, peas, bitter vetch, and lentils (pashkevych, 2008). the frequent recovery of hulled wheat plants from tripolye sites supports the notion that these crops were important components of the tripolye diet (zbenovich, 1996). these cereals may have been consumed as porridges, as indicated by crushed hulled wheat grains found inside a pot at the site of maydanetske (pashkevych, 2008). zooarchaeological evidence indicates that tripolye populations also practiced animal husbandry. tripolye livestock herds included cattle, pigs, sheep, and goats (markova, 2008; zhuralev, 2008). although the relative importance of each domesticated animal species varies between sites, cattle are often dominant (korvin-piotrovskiy, 2012). at the sites of traian -doalul viei and tirpesti i cattle make up over 45% of the faunal osteological material (ellis, 1984; marinescu-balcu, 1981). however, at the site of mayaki, sheep and goats make up 64% of the faunal assemblage, while at luka-vrublevetska, pigs are the most common species (ellis, 1984). in addition to agropastoral activites, tripolye populations engaged in hunting and gathering a wide range of wild species (lillie, 2008). gathered foods like wild grapes, cornelian cherries, plums, and pears have been identified at tripolye sites (pashkevych, 2004), and identification of animal species such as roe deer, red deer, wild pigs, aurochs, and catfish demonstrate that hunting and fishing were also practiced (korvin-piotrovskiy, 2012). for some tripolye populations it is likely that hunting greatly contributed to the diet, as wild animals comprise over half the zooarchaeological material at the ci period site of kolomyishchina (lillie, 2008). tripolye settlements vary in size, ranging from small seasonal sites to large permanent settlements (chapman, 2010). villages are located near permanent sources of water and are usually on the edge of the first river terrace or on promontories of steep river banks (zbenovich, 1996). some settlements dated to the middle period (b period) of the tripolye culture are found to be fortified with ramparts or surrounded by ditches (passek, 1961; markevich, 1981). early (a period) tripolye hamlets and villages are relatively small and vary in aerial extent from 0.5-6 hectares, usually containing fewer than 15 residential structures (zbenovich, 1996). in the later periods (b-c periods), many villages reached 20-40 hectares in size and were composed of an average of 200 dwellings (zbenovich, 1996). some later settlements were extremely large, such as talyanki, which was 450 hectares in area (kruts, 1989). these “megasites” were the largest in europe at the time (kruts, 2012) and were occupied year-round for a period up to 50 years, representing relatively sedentary settlement practices (korvin-piotrovskiy et al., 2012). the tripolye were a densely settled group, with the population density of the dniester area estimated at 12 individuals per square kilometer, making it one of the most densely settled areas in europe (korvinpiotrovskiy, 2012). likewise, the site of talyanki has been estimated to contain over 2,000 residential structures and have a population of 14,000 individuals (kruts, 2012), rivaling major prehistoric urban centers. 19 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 materials and methods the dental sample used to test our hypothesis include all known dentitions and loose teeth excavated from verteba cave, a mortuary site located outside the modern village of bilche zolote, ternopil oblast, ukraine (figure 1). the human remains found in the cave have been attributed to the eneolithic tripolye culture based on associated pottery, lithics, and ceramic figurines. radiocarbon dating of the human bone, faunal remains, charcoal, and pottery from verteba cave place the site’s use between 3800-2600 calbc (nikitin et al., 2010). analysis of pottery places the use of the cave during the bii, ci, and cii periods of the tripolye relative chronology. very few human remains attributable to the tripolye are known prior to the cii period, making the skeletons from verteba cave extremely valuable in terms of studying the biology and mortuary customs of this population. the sample was collected over the course of two periods of excavation. the most recent excavations took place over the field seasons of 2008 and 2012, and were conducted by the authors. these excavations yielded a minimum number of 36 individuals recovered as comingled secondary burials, mixed with pottery, ceramic figurines, stone and bone tools, and faunal remains. this material is housed on site by the borschiv regional museum. in addition to the specimens collected during the two recent field seasons, the remains of a minimum of 24 individuals were examined that were excavated from verteba cave during the late 19th century by polish archaeologists. these human remains are curated at the museum of archaeology in krakow, poland. only crania and mandibles are present in the krakow museum collection. although detailed field notes are not available regarding the excavation of the material from the 19th century, their association with diagnostic tripolye pottery supports the pooling of this sample with the more recently excavated material. a pooled sample of 231 permanent teeth from a minimum of 35 individuals was examined for enamel hypoplasias (table 1). a total of 121 permanent teeth representing a minimum of nineteen individuals were collected during the two most recent field seasons. of the 121 teeth, thirteen are not associated with a maxilla or mandible. a total of 110 permanent teeth representing a minimum of 16 individuals were available for study in the krakow collection. twentyone of the teeth in the krakow collection were not associated with a mandible or maxilla. due to the comingled nature of the burials, sex and age were assigned to individual crania and mandibles. ages-at-death were determined using dental development, dental attrition, and cranial suture closure (buikstra and ubelaker, 1994; lovejoy, 1985; meindl and lovejoy, 1985). due to the fact that more accurate aging methods could not be employed since no associated os coxae were available, individuals were segregated into age categories of “subadult” and “adult”. sex was determined for adults using the standard morphological characteristics (buikstra and ubelaker, 1994; walker, 2008). all of the teeth were examined for the presence or absence of enamel hypoplasias. the lesions were recorded following the method described by lukacs (1989; 1992) and temple (2010), with teeth examined macroscopically under diffuse lighting with a second light source positioned at an oblique angle to the specimen. a handheld 10x magnifier was used in some cases to help identify defects. this technique allows for optimal perikymata detection. to avoid confusing enamel hypoplasias with normal perikymata, the spacing of adjacent perikymata were compared to potential defects (skinner et al., 1995). each tooth examined was scored as either having an enamel hypoplasia present or absent. for teeth with hypoplastic lesions, the number of enamel hypoplasias present was recorded. the number of individuals displaying at least one enamel hypoplasia was also recorded. in verteba cave, some maxillae and mandibles representing single individuals are associated with one another, while others are isolated. when associated, upper and lower jaws are counted as single individuals. in cases where isolated mandibles and maxillae were not definitively associated with their occluding jaw, the isolated element is treated as an individual. this potentially overestimates fig. 1. location of verteba cave. 20 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 the number of individuals present in the sample, however, we believe it provides the most appropriate way to organize the available dental material. loose teeth were not included in the individual count. wear in the verteba cave sample was not severe and no tooth crowns had lost over one-third of their height to macrowear. therefore, wear did not bias the identification of enamel hypoplasias in the sample. the data on enamel hypoplasias among the tripolye from verteba cave will be presented in two ways following lillie (1996) to allow for statistical comparison with ukrainian hunter-fisher-gatherer populations. the first is the tooth count method, where the number of teeth with at least one enamel hypoplasia is presented as a ratio to the total number of observable teeth. this method has the advantage of using a large sample size, which increases the power of statistical analysis (lukacs, 1992). one drawback to the tooth count method is that it may overestimate stress. single stress events are recorded on all teeth developing at the time of a physiological insult. therefore, the tooth count method can overestimate the stress experienced by a population by treating all of the defects resulting from one stress episode as representing independent stress events. the second way enamel hypoplasia data will be presented is using the individual count method, where each dentition representing a single individual is scored as either having one or more enamel hypoplasias or as lacking hypoplasias altogether. the individual count method has the advantage of focusing on the individual, the primary unity upon which selection acts (lukacs, 1992). one disadvantage of using the individual count method with prehistoric skeletal samples is that it often results in small sample sizes and reduces the power of statistical analysis (lukacs, 1992). the relative frequencies of enamel hypoplasias for agriculturalists and hunter-fishergatherers are compared using χ2-tests (α=0.05). a recent study by hassett (2012) has demonstrated that, as compared to microscopic methods, examination of teeth with the naked-eye provides a minimum estimate of the number of hypoplastic defects. as microscopic analysis was not possible with the sample from verteba cave, the current data will be regarded as a conservative approach to quantifying systemic stress among prehistoric populations from ukraine. results the eneolithic tripolye agriculturalists from verteba cave have significantly more enamel hypoplasias than the mesolithic/neolithic hunter-fishergatherers when examined using both the tooth count (χ2=168.993, p<0.001) and individual count methods (χ2=20.58, p<0.001)(table 2). the tripolye have at least one enamel hypoplasia on 18.18% of the teeth tooth type teeth tooth type teeth maxillary mandibular incisors 17 incisors 2 canines 19 canines 5 premolars 43 premolars 18 molars 92 molars 35 total maxillary 171 total mandibular 60 table 1. composition of sample by tooth type sample ratio of teeth with at least 1 hypoplasia to total teeth observed ratio of individuals with at least 1 hypoplasia to total individuals observed verteba cave tripolye agriculturalists 42/231 17/35 mesolithic/neolithic hunter– fisher– gatherers (lillie, 1996) 43/2284 18/141 table 2. enamel hypoplasia frequencies 21 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 examined. in comparison, the hunter-fisher-gatherers have enamel hypoplasias on 1.88% of teeth. among the tripolye, 48.57% of observable individuals had at least one enamel hypoplasia, as compared to 12.77% of individuals in the hunter-fisher-gatherer sample. the rate of enamel hypoplasias in tripolye subadult (2/4 individuals) and adult dentitions (15/31 individuals) was similar. hypoplasias occurred at the highest prevalence on canines (45.83%), followed by incisors (33.33%), premolars (19.67%), and molars (10.24%). this pattern of prevalence by tooth type is not unexpected based on the known differences in susceptibility (goodman and rose, 1990). discussion analysis of enamel hypoplasias indicates that the agropastoral tripolye experienced significantly more systemic physiological stress than earlier hunterfisher-gatherers. this suggests that the introduction of agriculture and its associated sedentary lifestyle had negative consequences for human health in prehistoric ukraine. the results lead us to accept our hypothesis that the transition to agriculture was detrimental to health in our study area. however, due to the small sample size of dentitions from verteba cave, the results must remain preliminary. excavations are ongoing at the site with the aim of expanding the sample size. enamel hypoplasias form during the period of enamel development and leave an indelible record of systemic stress that occurred during infancy and childhood (larsen, 1997). weanling stress, diarrheal diseases, malnutrition, and infection are all commonly implicated as causative agents in the formation of enamel hypoplasias (goodman and rose, 1990). nutritional stress engendered by an agricultural diet may be a contributing factor to the higher rates of systemic stress observed among the tripolye. cereals were a major component of the tripolye diet (zbenovich, 1996), and may have been a primary weaning food in the form of porridges (pashkevych, 2008). however, cereals lack essential amino acids, such as lysine, are a generally poor source of protein, and are deficient in vital minerals such as iron (baynes and bothwell, 1990; abdel-aal and hacl, 2002). high reliance on cereals, especially as weaning foods, and reduced dietary variability as a consequence of an agricultural economy could have resulted in malnutrition and contributed to the relatively high systemic stress observed in the tripolye skeletal sample. the practice of animal husbandry by the tripolye makes it likely that they were consuming at least some proteinand nutrient-rich animal products and meat. however, mesolithic/neolithic groups from ukraine had diets highly focused on the meat of terrestrial animals and fish, with a lesser focus on vegetation (lillie, 1996; lillie and richards, 2000). such a diet would be nutritionally superior to one focused on domesticated cereals, and likely contributed to the lower incidence of systemic stress observed among mesolithic/neolithic peoples in this study. in addition to dietary factors, changes in population density and behavior associated with the adoption of agriculture likely altered the disease ecology of the tripolye farmers as compared to the mesolithic/neolithic hunter-fisher-gatherers. both the farmers and the hunter-fisher-gatherers would have been affected by infections of enteric bacteria such as salmonella, e. coli, and staphylococcus (cockburn, 1971). likewise, both groups would have experienced some zoonotic diseases transmitted through insect bites and the consumption of contaminated meat (armelagos, 1990). however, as compared to the mobile mesolithic/neolithic hunter-fishergatherers who lived in small bands, the settlement of the tripolye in sedentary villages with high population densities would have resulted in a significantly different disease ecology. the densely settled dniester region and megasites such as talyanki would have easily met the threshold for the maintenance of contagious crowd diseases such as measles, influenza, smallpox, and mumps (armelagos, 1990). additionally, densely settled sedentary populations, such as the tripolye, would have quickly contaminated their environments with their own waste, leading to sanitary health hazards (larsen, 1995). this environmental contamination can lead to diarrheal diseases and parasitic infections, which can result in malnutrition through a reduction in the efficiency of nutrient absorption and the loss of nutrients to parasitic activity (walker, 1986). diarrheal disease can have especially harmful effects on subadults (walker et al., 2009), and were likely a contributing factor to the elevated systemic stress documented in the tripolye agriculturalists. by contrast, the low population density of mesolithic/neolithic hunter-fisher-gatherers would have precluded the existence of contagious crowd diseases, and their mobile lifestyle would have prevented infections resulting from environmental contamination (armelagos, 1990). the tripolye would have also experienced close contact with domesticated animals via the practice of pastoralism, which would have significantly altered their disease ecology as compared to earlier hunter22 biological implication of agriculture in ukraine dental anthropology 2014 │ volume 27 │ issues 01 and 02 fisher-gatherers. close contact with domesticated animals would have exposed the tripolye to novel zoonotic diseases and infections including tapeworm parasites, viruses, rabies, and tuberculosis (armelagos, 1990). one specific cultural practice may have made the risk of zoonotic diseases especially severe for the tripolye. although the reconstruction of houses has been controversial in tripolye archaeology, it seems that they constructed two-story structures where the ground floor served as a stable for animals and the top floor was used for human habitation (korvin-piotrovskiy et al., 2012). the ground floor of these structures was constructed using timber to build a log cabin-like frame that would have provided a sturdy structure to contain animals, unlike wattle-and-daub walls, which are easily destroyed by pigs (korvin-piotrovskiy et al., 2012). by keeping farm animals in their homes, the tripolye greatly increased the likelihood of contracting zoonotic diseases and probably resulted in a substantial parasite burden for the population. the level of systemic stress documented among the tripolye from verteba cave is higher than that of a late/final neolithic agricultural population from greece. papathanasiou (2005) analyzed 436 teeth from alepotrypa cave and found 8.3% of teeth to have at least one enamel hypoplasia. perhaps the tripolye experienced more systemic stress than greek agriculturalists due to their higher population density. it is interesting to note that the level of systemic stress documented in the greek agriculturalist sample is higher than that of the ukrainian hunterfisher-gatherers. the results of our study are in accordance with results obtained by wittwer-backofen and tomo (2008) who found central european agriculturalists to have more enamel hypoplasias than earlier huntergatherers. however, the results of our study differ from those obtained by bennike and alexandersen (2007) who found the rates of enamel hypoplasias to immediately decline and then increase following the transition to agriculture in scandinavia. this suggests that the biological implications of the adoption of agriculture were variable across europe, and further study is necessary to fully understand the impact of this transition on prehistoric health. conclusion the transition to agriculture was one of the most pivotal events in the biological and cultural evolution of our species. despite this importance, relatively little is known regarding how the adoption of agriculture affected the health of prehistoric european populations. this study addressed this weakness in the literature by using enamel hypoplasias to document the systemic physiological stress experienced by tripolye agriculturalists from ukraine. comparison of the tripolye with hunter-fisher-gatherers indicates that the transition to agriculture resulted in increased biological stress in this region. contextualizing the results archaeologically suggests that the higher prevalence of enamel hypoplasias may have been caused by malnutrition due to reduced dietary breadth and infection resulting from increases in population density, sedentism, and contact with domesticated animals. acknowledgements we would like to thank alexandr diachenko, sean rafferty, adam gordon, and jackie nadeau for helpful comments during the preparation of this manuscript, and alexandr dudar for his special assistance during excavations. we would also like to thank the students who participated in grand valley state university’s summer bioarchaeological 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price td, editors. europe’s first farmers. cambridge: cambridge university press. p. 57-92. 13 dental anthropology 2021 │ volume 34│ issue 01 the impact of hybridization on upper first molar shape in robust capuchins (sapajus nigritus x s. libidinosus) emma ayres kozitzky 1* 1 new york university hybridization, once viewed as rare and universally detrimental (dobzhansky, 1940; mayr, 1963), is increasingly viewed as a frequent and innovative evolutionary phenomenon (ackermann et al., 2019; arnold, 1997; taylor & larson, 2019). adaptive hybridization and fertile hybrid populations have been observed in a wide array of animals and plants, such as galápagos finches (grant & grant, 2020), toads (c. chen & pfennig, 2020), butterflies (jiggins et al., 2008), and poplar trees (chhatre et al., 2018). there is an especially rich body of literature on ancient and contemporary primate hybridization. genetic analyses have demonstrated that hybridization events occurred in many primate lineages during their course of evolution (de manuel et al., 2016; fan et al., 2018; kuhlwilm et al., 2019; svardal et al., 2017; tung & barreiro, 2017; zichello, 2018), including hominins (browning et al., 2018; l. chen et al., 2020; durvasula & sankararaman, 2020; green et al., 2010; huerta-sánchez et al., 2014; reich et al., 2011; slon et al., 2018). a growing number of primate taxa are proposed to have hybrid origins (burrell et al., 2009; detwiler, 2019; rogers et al., 2019; roos et al., 2019; thinh et al., 2010; tosi et al., 2000; wang et al., 2015). hybridization continues to shape genetic and phenotypic variation in present-day primate populations in both natural and anthropogenic contexts (alberts & altmann, 2001; bergman et al., 2008; e. l. bynum et al., 1997; cortés-ortiz et al., 2007; gligor et al., 2009; jolly et al., 2011; malukiewicz et al., 2015; mather, 1992). while genetic analysis has been crucial for exploring primate hybridization, there is a growing interest in understanding the impact of hybridization on morphology. studies of hybrid primate morphology offer unique insight into the effect of abstract to better understand the impact of hybridization on development and morphology, i analyze an understudied phenotype in hybrid morphology research: tooth shape. i apply a 2d geometric morphometric approach to compare variation in first upper molar cusp tip positions and crown outline shape among 31 crested capuchins (sapajus nigritus), 37 bearded capuchins (s. libidinosus), and 44 hybrids (s. nigritus x s. libidinosus). a principal components analysis shows that group membership accounts for a significantly greater proportion of variance along the first major axis of m1 shape variation than does allometry. while most hybrids have s. nigritus-like m1s, several possess a transgressive m1 shape not observed in either parental species. procrustes distances are greater in hybrids compared to the parental capuchins, and two-block partial least squares analyses show that hybrids exhibit weaker integration between cusp tip positions and crown outline shape. these results demonstrate that hybridization generates novel m1 shapes and support the hypothesis that destabilized development results in elevated phenotypic variance in hybrids. further studies of dental shape in hybrid primates will generate important data for on-going efforts to detect potential hybrids in the hominin fossil record and to understand the evolutionary outcomes of anthropogenic hybridization. *correspondence to: emma ayres kozitzky department of anthropology center for the study of human origins new york university new york, ny 10003 eak475@nyu.edu this paper was the recipient of the albert a. dahlberg prize awarded by the dental anthropology association in 2020. keywords: geometric morphometrics; molar shape; hybridization; robust capuchins 14 dental anthropology 2021 │ volume 34│ issue 01 rapid genetic recombination on phenotypic development and variation. many studies have evaluated soft tissue phenotypes in contemporary hybrid populations using traits that are easy to observe in the field and can be measured non-invasively, such as pelage color and distribution, head shape, and tail carriage (alberts & altmann, 2001; n. bynum, 2002; kelaita & cortés-ortiz, 2013; phillips-conroy & jolly, 1986). researchers have also studied the relationship between hybrid ancestry and hard tissue phenotype, such as skeletodental size, shape, and non-metric trait variation (ackermann et al., 2006; ackermann & bishop, 2010; boel, 2016; cheverud et al., 1993; eichel & ackermann, 2016; ito et al., 2015; kohn et al., 2001; phillips-conroy, 1978). the proximate aims of hybrid morphology research are to elucidate how hybrid morphology quantitatively and qualitatively differs from parental morphology and if different kinds of hybrids share diagnosable traits indicative of their hybrid ancestry (ackermann, 2010; ackermann et al., 2019). the data derived from hybrid morphology research has important broader implications for primate conservation and paleoanthropology. primate conservation biologists observe that the frequency of hybridization will likely increase as primate habitats are disturbed or destroyed by anthropogenic interference (detwiler et al., 2005; malukiewicz, 2019; thompson et al., 2018). rare, endangered primates may reproduce with more common heterospecifics if conspecific mates are difficult to find. extensive admixture between divergent taxa may result in loss of genetic and phenotypic diversity and ultimately fuse two lineages (seehausen et al., 2008), or it may generate novel diversity and prevent inbreeding depression (arnold & meyer, 2006). by studying the variation in hybrid phenotypes, conservation biologists may be able to understand if the outcomes of anthropogenic hybridization are harmful, neutral, or adaptive for endangered primate populations. paleoanthropologists acknowledge that hybrid hominins are likely present in the fossil record. fossil evidence demonstrates that multiple hominin taxa cohabited africa and eurasia throughout the pliocene and pleistocene and could have hybridized where their ranges overlapped (détroit et al., 2019; grün et al., 2020; herries et al., 2020; spoor et al., 2015). the genetic evidence for hybridization events throughout hominin evolution is substantial (durvasula & sankararaman, 2020; jacobs et al., 2019; sankararaman et al., 2016; skov et al., 2020; villanea & schraiber, 2019). the hybrid ancestry of several fossilized hominin individuals has been confirmed by ancient dna analyses (fu et al., 2015; slon et al., 2018). however, ancient dna preservation is rare in most of the hominin fossil record, so analyses of hard tissue phenotypes in extant hybrid primates can be used to assess the feasibility of using morphological indicators to identify hybrid hominin fossils (ackermann et al., 2019). the identification of hybrid hominin fossils remains an outstanding issue for reconstructing hominin phylogenetic relationships, as most the commonly used phylogenetic frameworks assume evolutionary relationships are hierarchical rather than reticulate (holliday, 2003). quantitative genetic theory states that in firstgeneration (f1) hybrids, phenotypic trait measurements controlled by additive genetic variation will be the midparental value (mpv), or the averaged parental measurements (falconer & mackay, 1997). tests of this theory indicate that while some f1 hybrid primate phenotypes exhibit the expected mpv (hamada et al., 2012), other traits in the same population may deviate from the expected phenotype (ackermann et al., 2006; cheverud et al., 1993; eichel & ackermann, 2016). positive deviations from the mpv in f1 populations is referred to as heterosis, or hybrid vigor, while negative deviations are evidence of dysgenesis, or hybrid breakdown. later-generation hybrids with higher genetic input from one parental taxon are expected to be more phenotypically like that parent, but some hybrids resemble one parent more than the other, regardless of parental genetic contribution (boel et al., 2019; ito et al., 2015). firstand later-generation hybrid populations sometimes exhibit transgressive phenotypes not observed in either parental population, such as extreme trait size, novel combinations of parental traits, or the presence of nonmetric craniodental anomalies (ackermann et al., 2014; ackermann & bishop, 2010; jolly et al., 1997). research on hybrid morphology in primates has documented a complex array of phenotypic outcomes that vary within and among hybrid populations (alberts & altmann, 2001). importantly, these outcomes are not universally maladaptive (charpentier et al., 2012) and may help hybrid populations occupy ecological niches unavailable to either parental population, thereby resulting in novel evolutionary lineages (arnold, 1997; zinner et al., 2011). the high morphological variability observed within and among hybrid populations is thought to be the result of destabilized development (clarke, 1993). the uniquely adapted developmen15 dental anthropology 2021 │ volume 34│ issue 01 tal regimes of two distinct parental taxa are unlikely to merge seamlessly in offspring and could result in perturbations during hybrid morphogenesis. this is supported by the observation that deviations from predicted f1 midparental phenotypes tend to be more pronounced with increasing genetic distance between parental populations (bernardes et al., 2017; z. j. chen, 2013; stelkens & seehausen, 2009). researchers have tested the hypothesis that hybrids experience destabilized development using tests of morphological integration and fluctuating asymmetry (alibert et al., 1994; jackson, 1973; klingenberg, 2003; klingenberg & mcintyre, 1998). tightly integrated trait complexes and highly symmetric bilateral trait measurements are hypothesized to reflect stable, canalized development. so, if hybridization results in developmental destabilization, hybrids are expected to exhibit weaker trait integration and greater fluctuating asymmetry between bilateral traits than parental taxa. some hybrids do meet these expectations (ackermann et al., 2014; leary et al., 1985; neff & smith, 1979), but others do not differ from observed levels of parental trait integration or fluctuating asymmetry (jackson, 1973; pallares et al., 2016). in some cases, hybrid samples exhibit stronger trait integration and bilateral trait symmetry than parents, indicating that hybrid development is more stable than parental development (alibert et al., 1994; boel et al., 2019; debat et al., 2000). despite growing interest in primate hybrid morphology, the relationships among hybrid ancestry, development, and phenotype remain unclear and difficult to predict. however, one of the most potentially informative anatomical regions for this research has also been one of the most understudied: the dentition. several lines of evidence suggest that in-depth analyses of dental phenotypic variation will produce valuable data for hybrid morphology research. anomalous dental non-metric traits are observed at high frequencies in some hybrid populations, such as supernumerary teeth, crown rotation and/or malformation, and dental crowding (ackermann et al., 2010, 2014; ackermann & bishop, 2010; goodwin, 1998; heidejorgensen & reeves, 1993). intergeneric hybrids of theropithecus gelada and papio hamadryas (“geboon”) exhibit combinations of parental traits in their dentitions, such as t. gelada-like enamel crenulation on p. hamadryas-like low-crowned molars, resulting in novel dental phenotypes (jolly et al., 1997). most of the geboon hybrids also exhibited maxillary cheektooth dimensions that exceeded the parental means. however, hybrids of more closely related baboon species p. hamadryas and p. anubis were not easily differentiable from parental species based on both metric and non-metric dental traits (phillips-conroy, 1978). similarly, dental non-metric trait expression did not discriminate between closely related macaca fuscata, m. cyclopis, and their hybrids (boel et al., 2019). further analyses of dental size, shape, and non-metric trait expression in extant primate hybrids would elucidate if hybrid primates exhibit shared patterns of dental trait variation. dental phenotypic analyses of hybrids also could help to understand if deviations from typical parental development generate the high variability observed in hybrid populations. mammalian dental development is well-studied, and models of dental development have been tested in both extinct and extant primates (evans et al., 2016; hlusko et al., 2016; jernvall & jung, 2000; ortiz et al., 2018; paul et al., 2017). the iterative nature of dental development results in predictable patterns of dental trait integration both within the same tooth crown and among metameres. the patterning cascade model claims that the duration of tooth germ growth and the spatiotemporal distribution and strength of embryonic signaling centers within the germ constrain possible cusp configurations and crown size in the fully formed tooth (jernvall, 2000). so, differences between parental and hybrid cusp configurations and accessory cusp expression likely reflect deviations in underlying patterning cascade pathways. similarly, the inhibitory cascade model states that mammalian mandibular molar number and relative size are dictated by embryonic signaling strength and duration of odontogenesis, so differences between hybrid and parental molar size relationships and molar number likely reflect differences in this developmental pathway as well (kavanagh et al., 2007). indeed, in a hybrid baboon population, supernumerary mandibular molars are positively correlated with increased molar row length, which suggests that dental development is prolonged in the hybrids compared to parents (ackermann et al., 2014). data derived from studies of hybrid dentitions is especially useful for conservation biologists and paleoanthropologists. results derived from studies of hybrid skulls and postcrania are not easily applied in living primate populations, but the teeth of primates in hybrid zones can be evaluated, photographed, or molded and cast during trapping expeditions (kelaita & cortés-ortiz, 2013; phillipsconroy, 1978). while skeletal data is certainly use16 dental anthropology 2021 │ volume 34│ issue 01 ful for paleoanthropologists interested in determining the feasibility of identifying hybrid ancestry using fossil morphology, teeth tend to be better preserved and comprise most of the hominin fossil record (bailey, 2002; gómez-robles et al., 2007; martinón-torres et al., 2012; wood & abbott, 1983). the genus sapajus is an excellent study taxon for hybridization research. the robust capuchin clade underwent rapid radiation and expansion during the pleistocene, and species often interbreed where their ranges meet (lima et al., 2018; lynch alfaro, boubli, et al., 2012), making them an appropriate analog for understanding hominin hybridization. a sample of hybrids of sapajus nigritus and s. libidinosus are housed at the smithsonian national museum of natural history (nmnh). sapajus nigritus and s. libidinosus shared a common ancestor approximately 2.6 ma and belong to different clades within the genus, the former belonging to a more ancient clade endemic to the atlantic forest of brazil, and the latter belonging to a recently evolved clade adapted to brazilian dry shrublands (lima et al., 2018; wright et al., 2015). both species are listed as ‘near threatened’ by the iucn red list of threatened species and both are known to occupy habitats disturbed by agricultural practices (melo, alfaro, et al., 2015; melo, fialho, et al., 2015). it is possible that anthropogenic hybridization could result in the loss of genetic and phenotypic diversity among robust capuchin species (lynch alfaro et al., 2014; martins et al., 2017). a morphological analysis of hybrid robust capuchins would establish if phenotypic diversity is impacted by hybridization. here, i apply 2d geometric morphometric (2dgm) techniques to study variation in first upper molar (m1) crown outline shape and cusp tip configuration among sapajus nigritus, s. libidinosus, and their hybrids. dental shape has been used to study population affinity and to characterize extinct and extant primate taxa (bailey et al., 2016; gamarra et al., 2016; gómez-robles et al., 2007, 2015; rizk et al., 2013), including robust capuchins (delgado et al., 2015), but has not yet been used to study patterns of morphological variation among hybrids and their parental taxa. the primary aims of this study are to explore variation and the factors driving variation in m1 morphology in hybrids compared to s. nigritus and s. libidinosus; to determine if m1 morphology can discriminate between hybrids and parental taxa; and to evaluate if hybrids exhibit evidence of destabilized dental development compared to parental taxa. based on previous hybrid morphology research, i tested the following predictions: 1) m1 shape is statistically distinct among s. nigritus, s. libidinosus, and their hybrids. 2) the mean shape of hybrid m1s is the midparental value (the mean shape of the combined parental sample). 3) there is more variability in m1 shape within the hybrid sample than within either parental sample. 4) hybrids exhibit weaker covariation between cusp tip configuration and crown outline shape than parental taxa. materials and methods my sample includes sapajus nigritus (n = 31), s. libidinosus (n = 37), and a hybrid sample of s. nigritus x s. libidinosus (n = 44). the dental sample comprises 112 right m1s (table 1). only specimens with unworn or minimally worn m1s were included. i used a nikon d500 dslr digital camera fitted with a macro lens and attached to a copy stand to photograph m1 occlusal surfaces. i positioned the m1 cementoenamel junction (cej) parallel to the lens and included a scale placed at the same level as the occlusal plane (bailey, 2004; gómez-robles et al., 2007). while directly referencing the specimen, i marked each of the four main m1 cusp tips (the paracone, protocone, metacone, and hypocone) on the digital images using the gnu image manipulation program version 2.10.12 (the gimp development team, 2019). if a specimen exhibited slight wear, i marked the cusp tip in the center of the wear facet. i uploaded the photographs to tpsdig2 version 2.31 to digitize a series of 2d landmarks (points of biological homology among specimens) and semilandmarks (non-homologous points of morphological interest; bookstein, 1997). landmarks 1 through 4 were placed on the tips of the paracone, protocone, metacone, and hypocone (figure 1). these landmarks capture variation in the position female male total sapajus nigritus 16 15 31 s. nigritus x s. libidinosus 21 23 44 s. libidinosus 21 16 37 total 58 54 112 table 1. number of m1s included in this study. 17 dental anthropology 2021 │ volume 34│ issue 01 of the main cusps relative to each other and relative to the crown outline. in order to examine variation in the shape of m1 crown outlines, i placed 30 semilandmarks around the perimeter of the occlusal surface, starting at the point of maximum curvature where the buccal and mesial margins intersect. i drew a closed curve around the crown outline, and then appended 29 additional equidistant semilandmarks to the curve (see figure 1). finally, i exported all landmark and semilandmark coordinates as a .tps file to rstudio version 1.2.5033 for analysis. all geometric morphometric analyses were performed using the r package geomorph (adams et al., 2020). first, i defined semilandmarks 5 through 34 as sliding semilandmarks. sliding semilandmarks can move along the crown outline between neighboring semilandmarks to optimize their position with respect to the average shape of the entire sample. this process removes random variation from the coordinate data introduced by the initial arbitrary placement of semilandmarks around the crown margin and converts semilandmarks 5 through 34 to homologous points statistically comparable to landmarks 1 through 4 (gunz & mitteroecker, 2013). next, i performed a generalized procrustes analysis (gpa) on the landmark and sliding semilandmark coordinates to remove the effects of specimen size, orientation, and position, leaving only variation related to shape. the gpa superimposes specimens by translating, scaling, and rotating the coordinates to generate an average shape, or consensus configuration, for the entire sample (bookstein, 1997; zelditch et al., 2012). i used the results of the gpa for all subsequent analyses. to explore and compare major axes of m1 shape variation among s. nigritus, s. libidinosus, and their hybrids, i conducted a principal components analysis (pca). to visualize variation in shape space, i plotted pc 1 against pc 2 and pc 2 against pc 3. i included 95% confidence ellipses for each taxon to illustrate within-taxon variability. then, to test the effect of allometry on m1 shape, i constructed twelve linear models using results from the pca (table 2a). each model tested the association between scores on pcs 1, 2, and 3 with taxonomic designation, logarithm-transformed centroid size, or a combination of both variables. the best-fitting model for pcs 1, 2, and 3 were selected using the function for akaike’s information criterion (aic) in the r package bbmle (bolker et al., 2020). i used warp grids representing the mean shape for each taxon to visually evaluate if and how m1 shape varies among groups. to statistically evaluate the extent to which m1 shape is morphologically distinct among these groups by maximizing intergroup differences, i extracted the first ten pcs derived from the pca (encompassing the majority of shape variation within the sample) for a discriminate function analysis (dfa). then i used the results from the dfa for a cross-validated assignment test. i measured withinand between-group variance using pairwise procrustes distances (the euclidean distance between two sets of shape coordinates; spoor et al., 2015). a procrustes distance equal to zero represents a pair of individuals with identical m1 shape, while increasing distance reflects increasing dissimilarity in shape. i evaluated statistical differences in procrustes distances among taxa using pairwise t-tests using bonferroni correction for multiple comparisons. i performed a two-block partial least squares analysis (2b pls) to evaluate the level of covariation between the position of cusp tips (block 1: landmarks 1 through 4) and the shape of the crown outline (block 2: sliding semilandmarks 5 through 34), and implemented a permutation procedure (n = 1,000 permutations) to test the r-pls correlation coefficients generated by the 2b pls for statistical significance. because calculation of the r-pls statistic is dependent on sample size, i employed a standardized z-score converted to pairwise effect sizes to compare the strength of integration among groups (adams & collyer, 2016). large pairwise effect sizes indicate that the level of morphological integration differs between the two samples. figure 1. the landmark (1-4) and semilandmark (5-34) configuration used to analyze variation in m1 cusp tip position and crown outline shape. m: mesial; d: distal; b: buccal; l: lingual. 18 dental anthropology 2021 │ volume 34│ issue 01 results mean m1 shape in parental and hybrid taxa the mean shapes for s. nigritus, s. libidinosus, and the hybrids compared to the pooled-sample consensus configuration are shown in figures 2a, 2b, and 2c, respectively. differences in mean shape are magnified by a factor of three to assist in visual interpretation. the average crown outline shape in s. nigritus is rhomboid, while that of s. libidinosus is more ovoid. the average crown outline in the hybrid sample is more mesiobuccally skewed than either parental taxon and has a waisted lingual margin. the two parental taxa exhibit similar intercusp distances relative to the crown outline, but the mean s. nigritus paracone, metacone and hypocone (landmarks 1, 3, and 4, see figure 1) are buccally displaced compared to the consensus cusp tips. the average hybrid protocone, paracone, and metacone (landmarks 1 through 3, see figure 1) are slightly mesially displaced compared to the consensus configuration. the average hybrid m1 shape differs from the expected midparental shape. the midparental m1 crown outline does not have the waisted lingual margin that is present in the hybrid mean outline, and the hybrid protocone, paracone, and metacone are mesially displaced compared to the expected midparental m1 cusp configuration. principal components analysis the first three pcs account for approximately half (48.1%) of the variation in m1 shape among s. nigritus, s. libidinosus, and s. nigritus x s. libidinosus. principal component 1 explains 20.8% of shape variation, while pc 2 explains 16.6% (figure 3a). the warp grids representing m1 shape at extreme ends of variation along each pc illustrate that m1s with low pc 1 scores have a mesiobuccally skewed rhomboid crown outline which tapers distally and a waisted lingual margin. the cusp tips are displaced towards the buccal margin. first molars with high pc 1 scores have squared, symmetrical outlines and roughly equidistant cusp tips. along pc 2, m1s with low scores have mesiobuccally skewed rhomboid outlines with cusp tips displaced towards the buccal margin, while m1s with high scores have more symmetrical crown outlines, increased buccolingual distance between the two mesial cusps and between the two distal cusps, and lingual displacement of the lingual cusps. there is substantial overlap among the three taxa, but hybrids tend to have low pc 1 scores and high pc 2 scores, while the parental taxa tend to have high pc 1 scores and low pc 2 scores. the 95% confidence ellipse for hybrids is much broader than those of the parental taxa, reflecting greater variation in shape space. principal component 3 accounts for 11.2% of m1 shape variation (figure 3b). first molars with low pc 3 scores have symmetrical and ovoid crown outlines and a rhomboid cusp tip configuration. high scores on pc 3 correspond to m1s with mesiobuccally skewed, rhomboid crown outlines with a waisted lingual margin, wide intercusp spacing, and all cusp tips displaced towards the periphery. there is very little separation among taxa in pc 2 vs. pc 3 shape space. the range of variation among s. nigritus individuals is almost entirely subsumed within the range of the hybrids. s. libidinosus tends to cluster on the low end of pc 2 away from s. nigritus and the hybrids. based on shape and size of the 95% confidence ellipses projected onto tangent space for each taxon, the hybrids exhibit the highest variation in m1 shape along pcs 2 and 3. regression analysis and allometry the regression analysis demonstrated that taxonomic designation explains more variation in pc 1 scores than does m1 size (tables 2a and 2b). approximately 20% (p < 0.001) of variation in pc 1 scores is explained by taxonomic designation. a post-hoc pairwise t-test using bonferroni adjustment for multiple comparisons showed that hybrids had significantly lower scores on pc 1 than figure 2. pooled sample consensus m1 shape (gray) compared to mean m1 shape (blue) among (a) s. nigritus, (b) hybrids, and (c) s. libidinosus. figure 2d illustrates the mean parental m1 shape (s. nigritus and s. libidinosus combined, light gray) and the transformation of the mean parental m1 shape into the mean hybrid shape (blue). all comparisons are magnified by a factor of 3 to aid in visual interpretation. m: mesial; d: distal; b: buccal; l: lingual. 19 dental anthropology 2021 │ volume 34│ issue 01 figure 3. scatter plots of (a) pc 1 against pc 2 scores, and (b) pc 2 scores against pc 3 scores derived from the pca of m1 shape. the warp grids illustrate the transformation of the consensus configuration (gray) into the shape of m1s with the lowest (blue) and highest (red) scores along pcs 1 and 2. ellipses represent 95% confidence intervals for each group. note that, while there is considerable overlap among the groups, the hybrids tend to exhibit lower pc 1 and higher pc 2 scores than the parental taxa, corresponding to m1s with skewed crown outlines, a waisted lingual margin, and wider intercusp distances. m: mesial; d: distal; b: buccal; l: lingual. 20 dental anthropology 2021 │ volume 34│ issue 01 table 2. results of the regression analysis assessing the effect of taxonomic designation and allometry on variation in the first three principal component (pc) scores. a) the best-fitting model for each pc is in bold. b) the best-fitting model for each pc is in bold. model # model terms r2 p-value 1 pc 1 ~ log(centroid size) 0.02 0.20 2 pc 1 ~ taxon 0.20 <0.001 3 pc 1 ~ taxon + log(centroid size) 0.22 <0.001 4 pc 1 ~ taxon * log(centroid size) 0.22 <0.001 5 pc 2 ~ log(centroid size) 0.06 0.008 6 pc 2 ~ taxon 0.11 0.002 7 pc 2 ~ taxon + log(centroid size) 0.17 <0.001 8 pc 2 ~ taxon * log(centroid size) 0.18 <0.001 9 pc 3 ~ log(centroid size) 0.01 0.29 10 pc 3 ~ taxon 0.07 0.02 11 pc 3 ~ taxon + log(centroid size) 0.09 0.02 12 pc 3 ~ taxon * log(centroid size) 0.09 0.08 pc model # aic daic df weight 1 2 -567.3 0.0 4 0.526 3 -566.7 0.6 5 0.383 4 -563.8 3.5 7 0.091 1 -546.3 21.1 3 <0.001 2 7 -586.3 0.0 5 0.653 8 -584.6 1.7 7 0.284 6 -581.3 5.0 4 0.054 5 -577.4 8.9 3 0.007 3 10 -619.6 0.0 4 0.478 11 -619.3 0.3 5 0.416 12 -615.6 4.0 7 0.066 9 -614.6 5.0 3 0.040 21 dental anthropology 2021 │ volume 34│ issue 01 both s. nigritus and s. libidinosus (p = 0.003 and p < 0.001, respectively), but no significant difference in pc 1 scores between s. nigritus and s. libidinosus (p = 0.99; figure 4a). more complex models testing the effect of taxonomic designation on the relationship between pc 1 scores and m1 size were nonsignificant. change in m1 shape along the main axis of variation is not driven by size alone. however, the next-best-fitting model according to aic suggested that the average pc 1 score estimated from m1 size varies by taxon. a more complex model is required to explain variation in pc 2 scores. first molar size and taxonomic designation only explain 6% (p = 0.008) and 11% (p = 0.002) of variation in pc 2 scores, respectively, and a comparison of the two models indicates that pc 2 ~ taxon is a better fit than pc 2 ~ log(centroid size) (f = 5.93, p = 0.02). a post-hoc comparison of differences in pc 2 scores by taxon indicates that s. libidinosus has significantly lower pc 2 scores than the hybrids (p = 0.001; figure 4b); all other pairwise comparisons are non-significant. a multivariate model combining the effect of taxonomic designation and m1 centroid size explains 17% (p < 0.001) of variation in pc 2 scores and is a significantly better fit than pc 2 ~ taxon. there is no significant increase in explanatory power with the addition of an interaction term describing change in the slope of the relationship between m1 shape and size among taxa (f = 1.12, p = 0.33). so, variation in shape along pc 2 is partly driven by size, but the average pc 2 score estimated from m1 size differs by taxon. as with pc 1, taxonomic designation explains the most variation in pc 3 scores rather than m1 size. however, the amount of variation in pc 3 scores explained by taxonomic designation is small (r2 = 0.07, p = 0.02), and a post-hoc comparison average pc 3 scores by taxon indicates that the only significant difference among taxa is between s. libidinosus and the hybrids (p =0.016, figure 4c). comparisons with more complex models accounting for different size/shape relationships by taxon do not add significant explanatory power. discriminant function analysis results for the discriminant function analysis are illustrated in figure 5. the dfa maximized differences in between-group variation, but there is little separation among parental species and their hybrids along linear discriminant functions (lds) 1 and 2. along ld 2, there is some separation between s. libidinosus, which clusters at the positive end, and s. nigritus and hybrids, which both cluster toward the negative end. most of the hybrids have negative loadings on ld 1 and ld 2. the results of the cross-validated assignment test are presented in table 3. the percentage of individuals correctly classified to their a priori assigned taxon ranges from only slightly better than chance in s. nigritus (61.3%) to moderate in s. libidinosus (73.0%). in the hybrid group 70.5% were correctly assigned as such. both s. nigritus and s. libidinosus misclassified individuals were more frequently assigned to the hybrid group than to the wrong parental taxon, reflecting higher variation in m1 shape among hybrids. procrustes distances within and among taxa the mean pairwise procrustes distances in m1 shape are listed in table 4, and frequency distributions of pairwise procrustes distances within and between taxa are visualized in figure 6. the average distance for the entire sample is 0.06. withintaxon shape variability is highest for the hybrids (distance = 0.059) compared to the parental taxa (s. nigritus = 0.055, s. libidinosus = 0.053). all three taxa have significantly different mean procrustes distances (p < 0.001). the between-taxa comparisons show a greater degree of similarity between s. libidinosus and s. nigritus m1 shape (distance = 0.058) than between each parental taxon and the hybrids, and there is approximately equal distance between the parental taxa and the hybrids (s. nigritus vs. hybrids = 0.061, s. libidinosus vs. hybrids = 0.062). s. nigritus s. nigritus x s. libidinosus s. libidinosus % correct s. nigritus 19 8 4 61.3 s. nigritus x s. libidinosus 5 31 8 70.5 s. libidinosus 4 6 27 73.0 table 3. results of the cross-validated assignment test. the number of individuals correctly assigned to their a priori designated taxon are in bold. 22 dental anthropology 2021 │ volume 34│ issue 01 figure 4. box-and-whisker plots and scatterplots of comparing the relationship among taxonomic designation, log-transformed m1 centroid size, and scores for (a) pc 1, (b) pc 2, and (c) pc 3. the p-values for significant differences in pc scores between groups are indicated above the brackets. the red dashed regression line on each scatterplot represents a simple pc score ~ log(centroid size) model. indicates the line of best fit for the pooled sample (pc 2 ~ log(centroid size)). based on akaike’s information criterion, the variation in pc 1 and 3 scores is best explained by taxonomic designation (table 2b), while average pc 2 scores estimated from log(centroid size) significantly differ among taxa (indicated by separate lines of best fit for each taxon; pc 2 ~ taxon + log(centroid size)). 23 dental anthropology 2021 │ volume 34│ issue 01 figure 5. scatter plot of lds 1 and 2 derived from the linear discriminant function analysis, in which among-group differences in m1 shape are maximized. ellipses represent 95% confidence intervals for each group. first molar shapes along the low end of lds 1 and 2 are shown in blue, while shapes for m1 on the high end of lds 1 and 2 are illustrated in red. m: mesial; d: distal; b: buccal; l: lingual. s. nigritus s. nigritus x s. libidinosus s. libidinosus s. nigritus 0.055 s. nigritus x s. libidinosus 0.061 0.059 s. libidinosus 0.058 0.062 0.053 table 4. mean pairwise procrustes distances within and between taxa. a procrustes distance value of 0 means that there is no difference in m1 shape between two individuals. 24 dental anthropology 2021 │ volume 34│ issue 01 figure 6. frequency distributions of (a) within-group, and (b) between-group pairwise procrustes distances, reflecting degree of similarity in m1 shape between specimen pairs. vertical dashed lines represent the mean pairwise procrustes distance for each group. note that the hybrids exhibit elevated within-group procrustes distances, reflecting the higher morphological variability in this group compared to the parental taxa. also, between-group comparisons between one parental taxon and the hybrids exhibit higher mean procrustes distances compared to the pairwise distances between parental taxa. 25 dental anthropology 2021 │ volume 34│ issue 01 covariation between cusp tip configuration and crown outline shape the results of the 2b pls analysis are summarized in table 5. there is a strong and statistically significant correlation between cusp tip configuration (block 1) and crown outline shape (block 2) for the combined sample (r-pls = 0.66, p = 0. 001). there are differences in covariation between blocks 1 and 2 among the three taxonomic groups. the two parental taxa exhibit high and significant correlations between blocks 1 and 2 (s. nigritus r-pls = 0.76, p = 0. 002; s. libidinosus r-pls = 0.75, p = 0.001), while the hybrids exhibit weaker correlation between cusp configuration and crown outline shape (r-pls = 0.63, p = 0.015). effect sizes for each sample indicate that the hybrids, compared to the parental taxa, exhibit weaker integration than expected based on its permutated sampling distribution. however, pairwise statistical comparisons indicate that there is no statistically significant difference in the strength of integration among groups (although at p = 0.07, the difference in integration between the hybrids and s. libidinosus does approach significance; table 5b). discussion the impact of hybridization on primate hard tissue morphology is difficult to predict. while traits under additive genetic control are expected to exhibit the midparental state in f1 hybrid populations, studies reveal that f1 morphology often deviates from expectations (ackermann et al., 2006; ito et al., 2015). frequently, f1 hybrid trait morphology is polytypic and individuals exhibit novel phenotypes not observed in either parental population (bergman et al., 2008; fuzessy et al., 2014; jolly et al., 1997). many commonly measured phenotypic traits are not under additive genetic control. hybridization may affect non-additive trait expression, resulting in heterosis or dysgenesis (z. j. chen, 2013). the recombination of two divergently adapted parental genomes in hybrids may disrupt the interaction and expression of non-additive genes that control complex physiological and metabolic networks, including growth and development. this ultimately relaxes the constraints observed in parental developmental pathways and is associated with increased morphological variability in hybrids. deviations from expected midpatable 5. results of the two-block partial least squares analysis. a) the r-pls value reflects the degree of covariation between configuration of the cusp tips (block 1, landmarks 1 through 4) and the shape of the crown outline (block 2, sliding semilandmarks 5 through 34). larger effect sizes are associated with stronger observed covariation between cusp tip and crown outline shape than expected based on the permutated sampling distribution. b) matrix of pairwise differences in 2b pls effect size measuring difference in the strength of integration between samples in the lower triangle with corresponding p-values in the upper triangle. r-pls p-value effect size s. nigritus 0.76 0.002 3.01 s. nigritus x s. libidinosus 0.63 0.015 2.26 s. libidinosus 0.75 0.001 3.94 taxa pooled 0.66 0.001 - s. nigritus s. nigritus x s. libidinosus s. libidinosus s. nigritus -0.78 0.47 s. nigritus x s. libidinosus 0.79 -0.07 s. libidinosus 0.60 1.44 - 26 dental anthropology 2021 │ volume 34│ issue 01 rental morphology in f1 hybrids are positively associated with increasing parental genetic divergence (allen et al., 2020; bernardes et al., 2017; stelkens & seehausen, 2009). for example, there are fewer instances of cranial and postcranial trait heterosis in hybrids of recently diverged tamarin subspecies than between crosses of more anciently diverged tamarin subspecies (cheverud et al., 1993; kohn et al., 2001). similarly, non-metric indicators of disrupted skeletodental development tend to be more frequently observed in primates with increasing parental divergence (ackermann et al., 2014; boel et al., 2019). beyond the first generation, hybrid morphology is expected to more closely resemble that of the parental population into which the hybrids have backcrossed (falconer & mackay, 1997). continuous trait values in the backcrossed offspring of an f1 hybrid and an individual from the parental population are predicted to be the average of the parental value and the mpv. some novel phenotypes observed in f1 hybrids persist in latergeneration hybrids regardless of parental genetic contribution. macaca fuscata x m. cyclopis macaques have enlarged, m. fuscata-like sinus size even in backcrossed individuals who derive most of their ancestry from m. cyclopis (ito et al., 2015), and transgressive non-metric dental traits are observed in backcrossed p. cynocephalus x p. anubis individuals (ackermann et al., 2014). the morphology of individuals in multigenerational hybrid zones depend on a combination of physiological, reproductive, and ecological selective pressures (charpentier et al., 2008; fourie et al., 2015; jolly et al., 2011; mourthe et al., 2019). these selection pressures structure the distribution of hybrid phenotypes across contact zones. for example, hybrids from the contact zone between p. anubis and p. cynocephalus in amboseli, kenya exhibit a continuous distribution of phenotypes ranging from more p. anubis-like to intermediate to more p. cynocephalus-like, while the phenotypic distribution of hybrids in the p. anubis x p. hamadryas contact zone in awash, ethiopia is bimodal with very few intermediate phenotypes (alberts & altmann, 2001; wango et al., 2019). phenotypically intermediate hybrids in awash also exhibit reproductive behaviors intermediate to those observed in parental taxa, and are therefore thought to be at a reproductive disadvantage when backcrossing with p. anubis or p. hamadryas compared to hybrids with predominantly parental phenotypes and behaviors (bergman et al., 2008). hybrids in recently formed anthropogenic contact zones show more continuous phenotypic distributions and symmetrical contribution of parental genes into the contact zone (malukiewicz, 2019). so, a biologically relevant understanding of phenotypic outcomes in hybrid populations requires information regarding a variety of endogenous and exogenous variables. this study assumes that the nmnh is correct in its taxonomic designations of the specimens used. however, the hybrids and parental taxa studied here have not been genotyped, as is preferable in analyses examining the relationship between phenotype and degree of hybridity (ackermann et al., 2006; boel et al., 2019; cheverud et al., 1993; hamada et al., 2012). the assumption that the parental taxa are not themselves admixed may be particularly problematic for robust capuchins, as sapajus species have a complex history of hybridization in secondary contact zones (lima et al., 2018). in addition, there may be cryptic hybrids in the sample with a high degree of genetic admixture but no phenotypic indication of hybridity (ackermann, 2010; kelaita & cortés-ortiz, 2013). regardless, the results of the analyses presented here, combined with results from previous research, allow for some predictions to be made regarding the genetic makeup of the robust capuchin hybrids. my analyses indicate that, while hybrid m1 shape largely falls within the range of variation observed in s. nigritus and s. libidinosus, some aspects of hybrid m1 shape are unique compared to parental morphology. while pc 1 typically captures the allometric component of shape variation (zelditch et al., 2012), in this study taxonomic designation explained a greater proportion of variation in pc 1 scores than did molar size (table 2). hybrids significantly differed from s. nigritus and s. libidinosus on the main axis of m1 shape variation in the pca. hybrids had significantly lower pc 1 scores than both parental taxa and higher pc 2 scores than s. libidinosus, corresponding to m1s with increased buccolingual distance between cusps and a waisted lingual crown margin (see figures 3 and 4). however, hybrids and s. nigritus did not exhibit significantly different pc 2 or pc 3 scores. so, some hybrids exhibit a unique molar morphotype compared to parents, while others cluster with s. nigritus. this was reflected by the reasonably accurate classifications generated by the dfa assignment test (table 3). sapajus nigritus had the lowest correct assignment (61.3%), with more individuals misclassified as hybrids than s. libidinosus (table 3). sapajus libidinosus specimens also were more often misclassified as hybrids than s. nigritus but exhibited the highest percentage of 27 dental anthropology 2021 │ volume 34│ issue 01 correctly classified individuals (73.0%). the results of the pca and dfa support recent revisions in capuchin taxonomy. based on genetic and morphological data, the capuchins are proposed to contain two genera: the gracile cebus capuchins and the robust sapajus capuchins (lynch alfaro, de sousa e silva-júnior, et al., 2012). the iucn recognizes eight sapajus species that can be subdivided into a more ancient clade that evolved in the brazilian atlantic forest and a clade that recently left the atlantic forest to spread throughout the amazon (lima et al., 2018). sapajus nigritus belongs to the more ancient clade, and retains morphological features indicative of arboreal living, such as longer limbs and tails. sapajus libidinosus belongs to the amazonian clade but has recently evolved morphological traits for terrestrial life in the dry shrublands of the brazilian cerradocaatinga, including thickened molar enamel and shorter, more robust limbs (wright et al., 2015). sapajus libidinosus is therefore the most morphologically derived robust capuchin species (wright et al., 2015). the results of the pca and dfa presented here indicate that s. nigritus and s. libidinosus exhibit statistically significant differences in m1 shape. hybrids cluster more with s. nigritus rather than with the more derived s. libidinosus. based on the tendency of the hybrids and s. nigritus to cluster along pcs 2 and 3, i would expect the hybrids to exhibit greater genetic affinity with s. nigritus. tail length has been shown to track degree of hybridity in macaques (hamada et al., 2012), so it would be interesting to test this in s. nigritus x s. libidinosus hybrids. mean hybrid m1 shape in this study is not the mpv (see figure 2). compared to the expected shape, the observed hybrid m1 mean shape exhibits buccolingual expansion and a waisted lingual margin. however, the mpv is expected only in f1 hybrids and only for traits under additive genetic control (falconer & mackay, 1997). it is highly unlikely that wild hybrid populations contain only f1 individuals (kelaita & cortés-ortiz, 2013; phillipsconroy & jolly, 1986). additionally, it is known that the genetic architecture controlling m1 size and shape is partly non-additive (hardin, 2019; hlusko et al., 2016). combined, these observations indicate that the deviation from the expected midparental m1 shape observed in this study are likely caused by the disruption of non-additive gene expression or epigenetic interactions in latergeneration s. nigritus x s. libidinosus hybrids. this suggests that the morphological impact of hybridization persists beyond early hybrid generations, as has been demonstrated in baboons and macaques (ackermann et al., 2014; ito et al., 2015). the s. nigritus x s. libidinosus hybrids exhibit evidence of destabilized dental development. measured by pairwise procrustes distances, hybrids exhibit statistically significant elevation of within-taxon variation in m1 shape compared to both parental taxa. this variation may be driven by relaxed constraints during dental development (fuzessy et al., 2014). indeed, hybrids exhibit lower mean correlation between cusp tip configuration and crown outline shape (r-pls = 0.63) compared to s. nigritus and s. libidinosus (r-pls = 0.76 and rpls = 0.75, respectively). hybrids tend to have wider intercusp distances and cusps positioned closer to the crown periphery than the parental taxa. cusp tips correspond to the position of embryonic signaling centers in developing tooth germs. the distance between cusp tips is controlled by the relative strengths of activator and inhibitor molecules excreted by each signaling center and the duration of germ growth. increased inhibitory signaling and/or prolonged germ growth are expected to result in fully formed teeth with widely spaced cusp tips (guatelli-steinberg et al., 2013; jernvall, 2000). so, the wide intercusp distances and weaker correlation of cusp configuration and crown outline shape observed in s. nigritus x s. libidinosus hybrids are likely the result of prolonged dental development and/or deviation in levels of signaling molecules compared to those observed in parental dental development. similarly, ackermann et al. (2014) found that the presence of supernumerary distomolars is associated with increased molar row length in f1 hybrid p. cynocephalus x p. anubis individuals, suggesting that dental development is prolonged in hybrids compared to parents. among other papionin hybrids, papio hamadryas x p. anubis hybrids exhibit unique molar size relationships compared to parental taxa, suggesting that developmental pathways controlling hybrid baboon molar size may be destabilized compared to unadmixed baboons (phillips-conroy, 1978). however, based on frequencies of dental non-metric trait expression and fluctuating asymmetry of bilateral cranial traits, there is no evidence for destabilized dental development in earlygeneration m. fuscata x m. cyclopis macaques (boel et al., 2019). it is possible that these observations support the prediction that the degree of developmental destabilization observed in hybrids is associated with parental divergence. sapajus nigritus and s. libidinosus shared a common ancestor around 2.6 ma (lima et al., 2018); p. cynocephalus 28 dental anthropology 2021 │ volume 34│ issue 01 and p. anubis diverged approximately 1.5 ma while p. hamadryas and p. anubis diverged approximately 800 ka (rogers et al., 2019); and m. fuscata and m. cyclopis are estimated to diverge as recently as 170 ka (chu et al., 2007). a comparison of dental phenotypic variation and integration among these different hybrid populations would confirm the relationship between the degree of parental divergence and destabilized development in hybrids. while non-metric dental anomalies are observed at high frequencies in some mammalian hybrid populations, this pattern is not shared by all extant primates. this calls into question the suggestion that certain dental non-metric traits, especially supernumerary distomolars or dental crowding, are evidence of significant hybrid ancestry in extinct hominins (ackermann, 2010; ackermann et al., 2019). however, continuous dental trait variation remains understudied, even though non-metric dental traits are often correlated with continuous trait variation (ortiz et al., 2018) and a homo sapiens fossil with substantial h. neanderthalensis ancestry exhibits extremely large upper third molars (fu et al., 2015). the results presented here suggest that transgressive m1 morphology that falls outside of the range of variation observed in well-defined hominin taxa may be indicative of hybrid ancestry in hominin fossils. further analyses comparing molar shape variation in other extant primate hybrids would confirm if this is a valid prediction. in terms of primate conservation, this study did not indicate that hybridization reduced phenotypic variation among hybrids of s. nigritus and s. libidinosus. rather, hybridization generated novel phenotypes not observed in either parental population. it remains to be determined if expanded intercusp distances in these hybrids facilitate ecological niche separation from other robust capuchin populations. conclusions the dentition has been an anatomical region of interest in hybrid research, but previous work has predominantly studied non-metric dental trait variation rather than tooth shape. the results presented here suggest that a more in-depth analysis of the impact of hybridization on continuous dental phenotypes and development is warranted. the shape of the first upper molar is statistically distinct among s. nigritus, s. libidinosus and their hybrids, and hybrids exhibit morphological evidence of destabilized development, including elevated within-sample variance and weaker correlation between cusp tip configuration and crown outline shape. the same analyses used here applied to the rest of the postcanine teeth would likely uncover other significant differences between the hybrids and parental taxa. a more comprehensive understanding of the impact of hybridization on dental development could be gained by further comparisons of continuous trait integration between metameres and between occluding upper and lower molars; and by comparing levels of fluctuating asymmetry of continuous traits in left and right antimeres. the data derived from such studies would offer crucial information for attempts to diagnose hybrid ancestry from fossil morphology and to understand the evolutionary outcomes of hybridization among endangered primates in degraded habitats. acknowledgements i thank darrin lunde for his assistance with accessing collections at the smithsonian national museum of natural history. i also thank shara bailey for her guidance throughout the conception of this project and for her feedback on this manuscript. references ackermann, r. r. 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(2011). the strange blood: natural hybridization in primates. evolutionary anthropology: issues, news, and reviews, 20(3), 96–103. foster and harris 2009.3 85 crowns of teeth vary both in size and shape, and this is well documented by dental anthropologists who have detailed the variations in the morphologies of all tooth types (e.g., korenhof, 1960; morris, 1965; turner et al. 1991; scott, 2008). in turn, differences in the number and size of cusps, cingular features, and other details of the crown influence tooth size (e.g., kondo and townsend, 2006). conversely, tooth size is statistically and developmentally associated with crown complexity (e.g., keene, 1968; garn 1977). researchers have traditionally focused on the maximum mesiodistal (md) and buccolingual (bl) diameters of teeth (goose, 1963), though other dimensions may be at least as informative (corruccini, 1979; hillson et al., 2005). aside from some australian and melanesian groups with very large tooth sizes, there are rather few obvious intergroup differences in crown dimensions, and this has dampened anthropologists’ enthusiasm for collecting tooth size data (e.g., lasker and lee, 1957; moorrees, 1957). the disinterest in odontometrics has been compounded by the slow growth of analytic methods that are tractable and actually address anthropological questions (see, e.g., reyment et al., 1984; hanihara and ishida, 2005). one early thought was that, if tooth crown sizes don’t vary much across populations, perhaps tooth shape would be informative (e.g., hrdlička, 1923; nelson, 1938; selmer-olsen, 1949). calculating shape indexes also extends logically from the numerous ratios calculated by anthropometrists, discriminatory effectiveness of crown indexes—tests between american blacks and whites candice l. foster and edward f. harris* college of dentistry, university of tennessee, memphis, tn 38163 abstract tooth crown shapes differ among human groups because the sizes and shapes of the constituent crown components differ. it was of interest to us whether there is patterned variation in crown indexes between sexes or among ethnic groups. the crown index—buccolingual width as a function of mesiodistal length—was analyzed here in terms of sex and race differences in a cohort of american black and white adolescents (n = 324) from the u.s. mid-south. the mandibular canine is distinctive in exhibiting significant sexual dimorphism in crown shape, with females being broader in terms of mesiodistal length. prior literature reports the crown indexes of several tooth types to be dimorphic, which does not occur here, showing that the extent of sexual dimorphism differs among groups. in contrast, we found that multiple crown indexes differ significantly between the samples of blacks and whites, with the largest differences in uc, up1, and lm2. of note, nature of the differences are tooth-specific, suggesting that divergence among groups at this microevolutionary level has shifted crown shapes along distinctive (rather than parallel) pathways. the optimum subset of crown indexes correctly allocates 67% of the specimens as to race; this percentage is not much better than chance, suggesting that crown indexes are of little forensic usefulness in discriminating among contemporary humans. dental anthropology 2009;22(3):85-92. osteologists, and craniometrists that emphasize shape rather than size differences (e.g., wilder, 1920; martin, 1928), though albrecht et al. (1993) provide some cautionary notes against the uncritical use of ratios. the crown index (bl/md times 100) has long been used as a measure of crown shape. selma thomsen (1955, p 4) states that, “this index was introduced by retzius, a swedish anatomist,” but she does not supply a citation. anders retzius (b. 1796 – d. 1860) is better known in dental circles as the person who described histological features of the enamel: “in ground section the enamel is marked by brown bands called the bands, striae, or incremental lines of retzius” (bhaskar, 1962, p 103). application of the crown index evidently caught on quickly; de terra reports it (zahnbogenindex) without explanation (de terra, 1905). the crown index expresses crown width (bl) as a function of length (md), so a large index reflects a broad-short crown form, while a small index indicates a narrow-long form. the index is only an approximate measure of shape because tooth crowns are not essentially rectangular in form. the purpose of the present study is to explore the utility of using crown indexes of the permanent teeth to distinguish between males and females and, secondly, correspondence to: edward f. harris, department of orthodontics, university of tennessee, memphis, tn 38163. e-mail: eharris@utmem.edu 86 to test for differences between american blacks and whites. these differences may suggest intra-specific (‘racial’) differences in modal crown development. so too, the data may be of forensic use in estimating the race and/or sex of an unknown specimen (e.g., ditch and rose, 1972). materials and methods the crown dimensions measured from full-mouth dental cases were obtained from 324 adolescents in whom all 28 permanent teeth (omitting third molars) were fully erupted. teeth were intact (not affected by caries, trauma, or casting defects). teeth from just one side of the arch were measured because of the essential symmetry of the dentition. electronic-readout sliding calipers were used (precise to 0.005 mm), with beaks machined to fit well into the embrasures, and the measurement method described by seipel (1946) was followed. subjects had been patients in the department of orthodontics at the college of dentistry, memphis, tennessee, and sample sizes were 52 black males, 74 black females, 94 white males, and 104 white females. cases were phenotypically normal, and cases with congenitally absent teeth (ignoring third molars) were not included (garn and lewis, 1970; kirveskari et al., 1978). the crown index of each of the 14 tooth types was calculated using a spreadsheet program, and two-way factorial analysis of variance (winer et al., 1991) was used to concurrently test for race and sex differences. stepwise discriminant functions analysis (cooley and lohnes, 1971) then was used to find optimal subsets of the variables that maximally separate the sexes (or the races). statistics were performed using jmp (sas institute, cary, nc) and spss (spss inc., chicago, il). results univariate analysis descriptive statistics are listed in table 1, where it is evident that the majority of mean crown indexes are above 100 simply because bl breadths exceed md lengths (keith, 1916). the maxillary premolars have the highest indexes, on the order of 130 for p1 and 140 for p2. at the other end of the spectrum, maxillary incisors (i1, i2) have means appreciably below 100 because their crowns are wide but narrow faciolingually. the lower molars also have small mean indexes, at about 94 (m1) and 97 (m2), probably because the talonid, which extends crown length mesiodistally, is well developed on these teeth. statistical tests for sex differences (table 2) are interesting because only one of the 14 f-ratios achieved significance (p < 0.05), but, of note, the significant sexual dimorphism (for the lower canine) is highly significant (p < 0.0001). in other words, while males tend to have larger crown dimensions than females (e.g., garn et al., 1967; potter, 1972), the length-to-width ratios tend to be the same in the two sexes for most tooth types. the exception is that the crown index for lc is appreciably higher in females than males (fig. 1), and inspection of the sizes shows that the sex difference is principally due to the much greater md length of lc in males (whereas the bl sex difference is trivial). this strong statistical difference suggests that lc crown shape may be useful for sex discrimination. half of the crown indexes (7/14) are significantly different between the black and white samples (table table 1. descriptive statistics for the crown index, by race and sex tooth black females black males white females white males type x sd x sd x sd x sd maxilla i1 81.92 6.42 81.07 6.78 81.37 8.76 80.55 7.07 i2 93.75 8.94 93.19 9.79 90.75 10.68 91.31 11.90 c 106.35 7.18 104.12 6.81 102.44 9.08 102.93 8.77 p1 130.51 5.75 129.52 6.85 132.61 7.41 133.35 8.01 p2 141.00 8.54 142.68 8.20 139.84 8.52 141.66 9.36 m1 109.50 5.72 109.39 6.17 110.58 5.26 111.26 5.56 m2 107.82 6.80 107.53 6.50 109.51 8.94 108.33 6.33 mandible i1 105.97 8.20 103.42 9.60 105.65 9.53 107.01 9.52 i2 102.87 7.20 101.52 9.64 100.89 8.51 99.38 9.37 c 104.37 6.63 99.83 9.27 104.17 9.15 100.21 10.00 p1 108.94 6.51 109.26 8.23 109.65 7.73 110.48 7.05 p2 118.40 8.25 120.30 9.07 117.70 7.94 118.72 8.16 m1 93.52 4.71 92.29 4.38 94.09 4.70 94.26 5.02 m2 95.90 6.48 93.03 6.19 97.05 5.87 98.60 5.89 cl foster and ef harris 87 table 2. results of factorial anova tests for race and/or sex differences in crown indexes tooth race sex interaction type f ratio p value f ratio p value f ratio p value maxilla i1 0.38 0.5404 0.93 0.3348 0.00 0.9857 i2 3.99 0.0466 0.00 0.9966 0.21 0.6448 c 7.22 0.0076 0.84 0.3589 2.05 0.1532 p1 12.79 0.0004 0.02 0.8825 1.09 0.2963 p2 1.17 0.2794 3.03 0.0826 0.00 0.9458 m1 5.20 0.0232 0.20 0.6572 0.39 0.5345 m2 2.14 0.1441 0.75 0.3876 0.27 0.6059 mandible i1 2.34 0.1272 0.31 0.5756 3.35 0.0680 i2 4.22 0.0409 2.04 0.1546 0.01 0.9372 c 0.01 0.9317 17.07 <0.0001 0.08 0.7803 p1 1.26 0.2629 0.44 0.5093 0.09 0.7684 p2 1.43 0.2331 2.33 0.1282 0.21 0.6465 m1 5.35 0.0213 0.93 0.3352 1.62 0.2041 m2 17.21 <0.0001 0.67 0.4152 7.47 0.0067 2) when assessed univariately (alpha = 0.05). there is, however, a complexity as to which group has the larger crown index (fig. 2). inspecting the f-ratios, two teeth stand out as particularly different, namely maxillary p1 and mandibular m2. in both comparisons, the white sample has the larger crown index, indicating that these teeth are more broad-and-short in whites than blacks. multivariate analysis we used stepwise discriminant functions analysis to identify the subsets of variables that are most predictive of sex and, separately, most predictive of race. prior probabilities were set to be equal across groups. as suggested by the univariate analysis (table 2), only the crown index of lc is predictive of a subject’s sex. when all 14 indexes are input into the discriminant algorithm (races combined), just lc is retained, and it correctly classified 62% of the cases as to sex using the jackknife (“leave-one-out”) method. this percentage is better than chance, but is not as reliable as other skeletal and dental methods (e.g., buikstra and ubelaker, 1994). using the 14 indexes to estimate race (either american black or white), the stepwise procedure retained 5 of the 14 variables (sexes combined). this is a fairly large number of variables, and it suggests that the crown indexes are not strongly intercorrelated (garn et al., 1967c). correct allocation is 67% (jackknife) fig. 1. boxplots showing the distributions of the crown index for mandibular canine. median indexes are higher in females than males in both the black and white samples. crown index in american blacks and whites 88 using these five variables. these five variables do not contribute equally to the discrimination, and the structure matrix shows that uc and lm2 are most informative. conversely, the crown indexes for up2 and lp2 contribute little. retaining just the three most useful variables gives this prediction equation: race = -11.856 – 0.080(uc) + 0.079(up1) + 0.101(lm2) correct allocation remains at 67% even with removal of the two least-informative variables. these values in the equation are the unstandardized coefficients, but their ranking is the same as when standardized: uc is the most predictive (i.e., it has the strongest correlation with the canonical function), and blacks have a higher index (relatively broader-and-shorter uc) than whites. lm2, with a higher crown index in whites, also is informative. the third variable is up1, and it also has a higher index in whites. values at the group centroids are 0.270 for whites and -0.461 for blacks. substituting actual numbers for these three crown indexes into the equation above yields a number, where a positive value suggests the specimen is a white, and a negative value suggests the specimen is a black. a value near zero is indeterminate, and the farther the value is from zero the more likely it is that the race assignment is reliable (campbell, 1984; kieser and goeneveld, 1989). the canonical function shows that uc, up1, and lm2 exhibit the best discrimination between blacks and whites when relying on tooth crown shape. signs of the coefficients show that separation of these two races depends on a contrast between upper canines with a short-and-broad outline (characteristic of blacks) compared to short-and-broad up1 and lm1 (characteristic of whites). this mix of crown shapes strengthens the view that crown morphologies have diverged independently among the tooth types over time (harris and harris, 2007). discussion the crown index is an approximation of true crown shape, and it provides a comparison of shape independent of size. in turn, the number and relative sizes of cusps—the component parts of the crown—affect crown shape. the number of cusps is determined by the number of secondary enamel knots (jernvall et al., 1994; thesleff and jernvall, 1997), though what controls knot formation is poorly understood. spacing of secondary enamel knots and subsequent expansion among the cusps prior to the cessation of growth by bridging due to dentinogenesis controls cusp size and the cusps’ spatial arrangement (e.g., butler, 1967), though again little is known about the developmental mechanisms (biochemical signaling) governing these growth processes (e.g., salazar-ciudad, 2008; salazar-ciudad and jernvall, 2002, 2004). physical anthropologists (as here) conventionally are limited in their analysis to the teeth themselves—the phenotypic end-products of ontogeny—so there is little to investigate about the formative processes. sexual dimorphism teeth tend to be larger in men than women, though the extent of sexual dimorphism is modest in humans compared to other species of the great apes (swindler, fig 2. plots of the mean crown index, by race and tooth type. seven of the 14 black-white differences are significantly different as judged univariately. blacks have larger indexes in the anterior region (incisors, canines) as denoted by the “b>w” code. indexes in the buccal segment (premolars, molars), in contrast, are larger in the white sample (“w>b”). this mixture of differences among teeth can be interpreted as region-specific changes in crown shape over the microevolutionary time separating these groups. cl foster and ef harris b b b b b b b b b b b b b b j j j j j j j j j j j j j j i1 i2 c p1 p2 m1 m2 i1 i2 c p1 p2 m1 m2 70 80 90 100 110 120 130 140 150 c r o w n i n d e x b blacks j whites maxilla mandible * b > w * b > w * w > b * w > b * b > w * w > b * w > b 89 2002). the traditional argument is that sex hormones, notably testosterone, enhance mitotic activity to create larger teeth in males (guatelli-steinberg et al., 2008). interestingly, enamel formation (amelogenesis) does not account for sex differences in tooth size (stroud et al., 1994, 1998), though that had been a reasonable supposition (moss, 1978). instead, differences stem from greater dimensions of the inner enamel epithelium that are established prior to tooth mineralization (e.g., corliss, 1976; avery, 1994). larger size—and any shape differences— stems from growth of the inner enamel epithelium, and dentin formation progresses internally from this epithelial margin (fig. 3). greater pulp dimensions in males (moore, 1989; woods et al., 1990) can be viewed as the volume created by the inner enamel epithelium that is not composed of dentine in the mature tooth. garn et al. (1967b) suggest that a sex difference in crown indexes follows logically from the observation that percent sexual dimorphism is greater in the bl than the md axis of teeth. this was true for his sample of whites (garn et al., 1966) and it also is true for the present data (not shown), where percent sexual dimorphism is greater in the bl axis for 10 of the 14 tooth types. this does not, however, translate into sex differences in the crown index. interestingly (fig. 4), garn’s sample of whites (yellow springs, ohio) possesses much greater sexual dimorphism across the crown indexes than the present sample of whites (memphis, tennessee). fully half (7/14) of the tooth types achieved a significant sex difference in garn’s sample, while, as we emphasized earlier, only the lower canine had a significant sex difference in the present study. lack of statistical significance is not due to type ii errors insofar as our sample sizes of whites are larger than garn’s. these inter-group differences may be influenced by technical issues, such as operator bias (kieser et al., 1990) or differences in instrumentation (garn et al., 1967a), but we favor the issue of regional differences in tooth size among “whites” across the united states—though virtually nothing is known about this. the present data on crown indexes show that growth of the male and female teeth are essentially isometric— that males are (using this index) enlarged analogs of the female archetype. in other words, while males have metrically larger teeth (e.g., mijsberg, 1931; garn et al., 1964, 1967d), their length-width ratios are proportionately enlarged versions of females (harris and hicks, 1998), and there is the retention of the same gnomon fig. 3. buccal view of a mandibular right m1 sectioned mesiodistally. the arrows mark the approximate heights of contour (defining maximum crown diameter), and it is evident that most of the “bulge” of the crown apical to the occlusal table is due to enamel thickness, but it also is contributed to by the convexity of the dentinoenamal junction that was formed by the inner enamel epithelium prior to mineralization. diagram modified from zeisz and nuckolls (1949). b b b b b b b b b b b b b b u i 1 u i 2 u c u p 1 u p 2 u m 1 u m 2 l i 1 l i 2 l c l p 1 l p 2 l m 1 l m 2 70 90 110 130 150 c r o w n i n d e x b ohio males ohio females b b b b b b b b b b b b b b u i 1 u i 2 u c u p 1 u p 2 u m 1 u m 2 l i 1 l i 2 l c l p 1 l p 2 l m 1 l m 2 70 90 110 130 150 b tenn males tenn females * * * * * * * * fig. 4. plots of the crown index for the 14 tooth types in (left) a sample of ohio whites (garn et al., 1967a) and (right) the present sample of whites from tennessee. asterisks mark the 7 tooth types that garn et al. reported as statistically significant, whereas just one of the 14 teeth was significantly dimorphic in the present study even though sample sizes are comparable. crown index in american blacks and whites 90 (shape) with increased size (thompson, 1948). the one exception is the mandibular canine, where females have a distinctly higher crown index. while the md and bl dimensions are smaller for females, their lc crowns are disproportionately shorter mesiodistally. that is, bl widths vary little between the sexes, and differences in md lengths are about three times larger than the width difference, yielding a larger crown index in females. black-white differences it has long been recognized that sub-saharan blacks have large teeth, especially compared to rather smalltoothed europeans (e.g., topinard, 1886; de terra, 1905), and more recent studies confirm this, including odontographies by shaw (1931) and jacobsen (1982). likewise, early black-white comparative studies (e.g., hrdlička, 1923; nelson, 1938; selmer-olsen, 1949) show that the dental differences are complex. differences in the crown index are location-dependent rather than uniform across the tooth types. a crude measure of this is that, of the 7 significant differences (fig. 2), three are due to higher indexes in blacks, while the other 4 are higher in whites. the governing principle is that blacks tend to have disproportionately broad crowns (compared to md lengths) in the anterior segment of the arches (incisors, canines)—so crown indexes are larger than for whites. conversely, the white sample has disproportionately broader (and/or mesiodistally shorter) crowns in the buccal segment (premolars, molars). these differences in proportionality led harris and rathbun (1991) to label the dentitions of sub-saharan africans and their derivative groups as “front loaded” in the sense that a greater portion of their overall crown size is distributed among the anterior teeth. people of european extraction, in contrast, tend towards the opposite expression, where greater portions of their overall crown area are apportioned to the premolars and molars. of course, these proportional differences are evaluated independently of the absolute sizes of the dentitions. this complexity of differences in crown indexes should be useful in forensic studies of estimating the race of an unknown specimen (ditch and rose, 1972). overview tooth crown size and shape are necessarily interrelated, and the present study assesses a time-honored approximation of crown shape, namely the crown index. samples of american blacks and whites were analyzed from the u.s. mid-south. • while human males typically have larger crown dimensions, most tooth types are not sexually dimorphic in these samples. the exception is the lower canine with a significantly higher crown index in females because of disproportionately short crown lengths. • several tooth types exhibit significantly different crown indexes between american blacks and whites, though the indexes are a mixture of higher and lower values. • three variables (uc, up1, lm2)—but especially the higher crown index of uc in blacks—are useful for discriminating between these samples of american blacks and whites. 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diet, health, and difference in non-adults from urban and rural roman britain anna rohnbogner¹* mary lewis¹ ¹university of reading, uk keywords: dental disease, carious lesion, romanisation, linear enamel hypoplasia, co-occurrence child health is an understudied subject in the archaeology of roman britain. most of what we know about growing-up in the province is derived from the classical literature. while archaeological research has mainly focused on the architectural grandeur of the towns and high status villa settlements (parkins, 1997; millett, 2005; mattingly, 2006; pearce, 2008; holbrook, 2015), rural settlements and their inhabitants have received scant attention ,preventing a more holistic view of life in britannia (taylor, 2007; mccarthy, 2013; breeze, 2014; fulford and holbrook, 2014). contrary to the long-held belief in the detrimental effects of the urban environment, recent bioarchaeological research has demonstrated that living in the romano-british countryside also negatively affected health (pitts and griffin, 2012; redfern et al., 2015). the late romano-british villa economy may have provided health challenges for its workers, a subject yet to be fully explored. while nonadult skeletons are widely acknowledged to provide an intricate measure of population fitness in the past (mensforth et al., 1978), comparisons of the morbidity and mortality of urban and rural romano-british children have yet to be carried out. a child’s diet would have reflected the cultural beliefs and social standing of his or her family. carious lesion frequency can therefore provide valuable information on access to resources, eating habits, and food preparation practices. in children, calcified plaque (calculus), and pathological conditions of the dentition such as periapical lesions, periodontal disease, and antemortem tooth loss are rare. carious lesion frequencies in the deciduous and permanent teeth, therefore, provide the most effective measure for discussing past dental health during childhood (halcrow et al., 2013). the presence of dental caries in children not only indicates the levels of carbohydrates consumed, but also informs on cultural practices such as pre-mastication, and sharing of foods or utensils (nield et al., 2008). carious lesions can cause considerable discomfort, resulting in intense pain, difficulty eating, reduced efficiency of the immune system (baqain et al., 2004), and can affect speech development (aligne et al., 2003). dental studies that focus on children are rare in the palaeopathological literature and tend to focus on individual sites or have small sample sizes (e.g. moore and corbett, 1973; whittaker et al., abstract dental disease in childhood has the potential to inform about food availability, social status, and feeding practices, in addition to contributing to a child’s overall health status. this paper presents the first comprehensive overview of carious lesion frequencies in 433 non-adults (1-17 years), and 6,283 erupted permanent and deciduous teeth from 15 urban and rural romano-british settlements. pooled deciduous and permanent caries rates were significantly higher in major urban sites (1.8%) compared to rural settlements (0.4%), with children from urban sites having significantly higher lesion rates in the deciduous dentition (3.0%), and in younger age groups with mixed dentitions. the differences in dental caries between urban and rural populations suggest disparities in maternal oral health, early childhood feeding practices, food preparation and access to refined carbohydrates. a richer, perhaps more ‘roman’, cuisine was eaten in the urban settlements, as opposed to a more modest diet in the countryside. the effect of early childhood stress on caries frequency was explored using evidence for enamel hypoplasia. co-occurrence of caries and enamel hypoplasia was highest in the major urban cohort (5.8%) and lowest in the rural sample (1.3%), suggesting that environmental stress was a contributing factor to carious lesion development in romano-british urban children. *correspondence to: anna rohnbogner archaeology, school of archaeology, geography and environmental science, university of reading, reading, uk, rg6 6ab, e-mail: a.j.rohnbogner@reading.ac.uk; annarohnbogner@hotmail.com 17 dental anthropology 2016 │ volume 29 │ issue 01 1981; o’sullivan et al., 1993; clough and boyle, 2010; redfern et al., 2012). this study will provide an overview of carious lesion frequency in non-adults from 1st to early 5th century ad urban and rural settlements in roman britain. due to the general absence of periodontal disease, periapical lesions, antemortem tooth loss, and calculus in the dentitions of children, this study relies on dental caries as the sole measure of childhood dental health. the aim of the study is to assess whether an urban or rural living environment impacted childhood dental health through the investigation on lesion frequencies of dental caries in the deciduous and permanent dentition. pathogenesis of dental caries in children dental caries is a progressive infectious disease of the deciduous and permanent dentition, with localised demineralisation of the dental hard tissues by organic acids (larsen, 1997). streptococcus and lactobacillus bacteria in the oral cavity metabolise sugars and starches, which create an acidic environment and demineralise tooth enamel (byun et al., 2004). teeth are remineralised as soon as ph levels are restored to neutral. if, however, the ph is low for a prolonged period, the dynamic between deand re-mineralisation is upset, resulting in a cavity (gussy et al., 2006). streptococcus mutans, the main cariogenic bacterium, is normally transmitted from the mother or other caregiver to the child through kissing or sharing implements (nield et al., 2008). colonisation with s. mutans can commence as early as six months old, although the highest risk for infection is at two years old. it takes around 13-16 months from colonisation for a lesion to develop (kawashita et al., 2011). ‘early childhood caries’ defined as caries in children aged 0-5 years, is a serious chronic condition in the modern world (afroughi et al., 2010). newly erupted deciduous teeth are particularly susceptible to dental caries due to incomplete maturation, large dental tubules and thinner enamel, which is insufficient in preventing the progression of carious lesions (aligne et al., 2003; schuurs, 2013). the area around the erupting tooth also provides favourable conditions for bacterial colonisation (schuurs, 2013). child saliva flow rate is slower than in adults, and has lower levels of secretory immunoglobin a (iga) concentrations. while iga begins to be produced after one month of life, its formation can be impaired by high levels of cortisol in the blood through stress. stress could therefore have a caries-promoting function. it may manifest as enamel defects, i.e. hypoplasia, which in turn may increase the risk of dental caries (boyce et al., 2010). enamel hypoplasias may cause dental caries to progress more quickly due to higher acid solubility of defective enamel, and greater adhesion of cariogenic bacteria at the site of a defect (hong et al., 2009). the presence of enamel hypoplasias in individuals with dental caries may therefore be a valuable indicator of early childhood stress in relation to dental decay, and it is of interest to evaluate their co-occurrence. using the jaws of modern children, afroughi and colleagues (2010) showed that once a tooth is infected, dental caries continues to spread to the teeth on either side or above, often in a symmetrical pattern. risk of lesion development was greater for maxillary posterior teeth than for anterior or mandibular teeth. early childhood caries may take on a rampant virulent form, known as ‘severe early childhood caries’ (secc), ‘nursing caries’ or ‘milk bottle syndrome’. the condition is characterised by rapid lesion development and dental decay primarily in the maxillary anterior dentition (berkowitz, 2003; azevedo et al., 2005). a probable case of secc has recently been identified by bonsall and colleagues (2015) in a 3-4 year old child from roman ancaster, lincolnshire. diet is a crucial factor in the onset and proliferation of dental caries. refined foods with a high carbohydrate and/or sugar content encourage the metabolic activity of oral bacteria and acid production, increasing the risk of lesion development (powell, 1985; prowse et al., 2008). a tough and fibrous diet has a cleaning effect, and vigorous mastication stimulates salivary flow, which is alkaline, buffering against plaque acids (duray, 1992; moynihan, 2000). soft sticky foods and prolonged snacking or sipping of sweetened fluids pose a greater risk for acid development (hallet and o’rourke, 2003). dental disease is usually described by the different surfaces of the tooth that are affected: the occlusal surfaces, smooth surfaces of the crown including the interproximal areas, or the root (moore and corbett, 1973). each of these surfaces has different cariogenic potential, therefore, the location of carious lesions on the tooth may provide insight into changes in diet (ortner, 2003). with the intensification of cereal agriculture, carious lesions at the root and cementoenamel junction rise, and with the introduction of refined sugars, interproximal and fissure carious lesions increase, especially in children (hillson 1996, 283). the romano-british diet there are a number of historical sources that make reference to ‘roman’ food and drink, including apicius’ collection of recipes, pliny the elder’s naturalis historia or galen’s medical writings (grocock and grainger, 2006; alcock, 2010). these sources reflect mediterranean practices of the literate upper classes in the 1st and 2nd centuries ad, and it remains unknown how these are relevant for exploring diet in roman britain. when comparing literary evidence on diet to recent isotopic and osteological studies of populations from rome (rutgers et al. 2009; killgrove and tykot 2013), velia (craig et al. 2009), and portus romae 18 dental anthropology 2016 │ volume 29 │ issue 01 (prowse et al. 2008), it transpires that a ‘typical’ roman diet as described in classical sources may not have been followed, or in fact existed. cereal products such as bread and porridge may have been the staple foods in britain, although variation across the social and geographical strata is expected (cool, 2006). sugars would have been available as fructose from fruits, fruit juices, honey and syrups, or glucose in the carbohydrates consumed (moore and corbett, 1973; bowman and thomas, 1994; cool, 2006; bogdanov et al., 2008; nassar et al., 2012). more advanced farming and plant cultivation techniques, alongside larger scale animal breeding, would have ensured a stable food supply for the army and nonproducing urban population, whilst also putting increasing demands on the workers in the countryside (mattingly, 1997; dobney, 2001; taylor, 2001; pitts and griffin, 2012; mccarthy, 2013; redfern et al., 2015). studies by king (1984; 1999; 2001) and cummings (2009) have demonstrated that access to meat and animal products was dependent on site type and status. overall, marine and freshwater fish became increasingly fashionable, probably as a result of following roman tastes (locker, 2007). isotopic studies on human bones (richards et al., 1998; redfern et al., 2010; cheung et al., 2012; müldner, 2013) and archaeobotany (van der veen, 2008; van der veen et al., 2007; 2008) have revealed temporal, cultural, social and sex differences in the consumption of terrestrial, plant, and aquatic foods at an inter-site and intra-site level. richard and colleagues’ (1998) study of poundbury camp in dorset showed that animal protein and marine foods were only available to the few. children are thought to have enjoyed more marine foods, and diet was more varied for the inhabitants of the towns (redfern et al., 2010; müldner, 2013). it also appears that marine and freshwater foods were primarily consumed in the urban environment rather than the surrounding villages, and that the male and female diet, at least within roman gloucester, differed (cheung et al., 2012). to the benefit of britons, a variety of new plant foods were introduced following the roman conquest, improving the nutritional value of the romano-british diet. examples include cherries, carrots, or plum, also beet and cabbage, which are high in nutrients and vitamins (van der veen et al., 2008). as a general pattern, plant foods were widely accessible and eaten in both town and country (van der veen et al., 2007). it is of note that some areas of the province differed. access to new plant foods was more restricted, or perhaps opposed, in the southwest (van der veen et al., 2008). in children, dietary experiences would have started at weaning with the gradual introduction of solid foods to supplement breastmilk. galen’s writings and soranus’ gynaecology, both dating to the 2nd century ad, recommend the introduction of supplementary foods from around six months (fildes, 1986; temkin, 1991). weaning would have been complete by 2-4 years old, a practice that has been supported by isotopic analysis of non-adults from england and italy (fildes, 1986; fuller et al., 2006; prowse et al., 2008; prowse, 2011; nehlich et al., 2011; redfern et al., 2012; powell et al., 2014). the roman weaning diet comprised mainly of cereal foods, such as porridge, or bread mixed with milk, wine or honey (temkin, 1991; garnsey, 1999). pre -mastication of foods for weanlings was warned to be harmful; however, the fact that the practice needed to be discouraged suggests it was a known method of infant feeding (bradley, 1986; temkin, 1991). honey was also used as a popular medicinal aid. soranus suggests rubbing honey on the gums of teething infants to soothe their pain (temkin, 1991). once weaned, the contents of the roman early childhood diet are unknown. if diet was influenced by location and status, children would have been subjected to differential food allocation. child dental disease rates may then also differ, depending on urban and rural site types, or high versus low status settlements. a large scale investigation of dental caries rates may therefore provide the first detailed evidence for cultural practices and dietary habits of children in roman britain. materials and methods site classification the terms ‘urban’ and ‘rural’ are used to characterise the nature of the settlement rather than its geographic locale. in order to allow for a comparison of carious lesion frequencies between settlements under different levels of roman influence, sites were divided into major urban (coloniae, civitates), minor urban (nucleated/small towns) and rural settlements (villages, farmsteads, villa estates). a common denominator for romano-british towns, whether large or small, is the dependence on the hinterland for agricultural surplus to feed the non-producing urban population (mattingly, 1997; morley, 1997). ‘major urban’ sites were defined as large legal and administrative settlements with a series of features including a grid layout for the street system and organised planning throughout, with public buildings, a forum and a spiritual focus (wacher, 1974; burnham and wacher, 1990; millett, 1990; laurence et al., 2011). ‘minor urban’ centres displayed some urban aspects, such as evidence for town planning and a market to facilitate local trade (hingley, 1989; burnham, 1993; 1995; millett, 1995; wilson, 2011). rural sites were defined as undefended farmsteads, villages, or villa estates with a predominantly agricultural focus (mccarthy, 2013). depending on their location, rural sites would have exhibited varying economic and socio-cultural dependence on nearby towns (laurence et al., 2011; white, 2014). however, their agricultural focus still rendered them as rural in character and urbanisation of the countryside to the extent seen in italy was not apparent in roman britain (laurence, 19 dental anthropology 2016 │ volume 29 │ issue 01 2011). current models on life in the romano-british countryside consider villa economies as estates managed by landowners, with a peasant population that cultivates the land as tenants or freeholders, living either on the estate or surrounding villages (taylor, 2001; mattingly, 2006; mccarthy, 2013; breeze, 2014). there is a growing awareness of the difficulty in classifying romano-british settlements (mattingly, 1997; millett, 1999; burnham et al., 2001; millett, 2001; pearce, 2008; rogers, 2011), and it is important to bear in mind that power in roman britain was not exclusively urban, as the elite often resided in the countryside or a town’s immediate hinterland (parkins, 1997; pitts and perring, 2006). in addition, not all urban cemeteries would have contained those living and dying exclusively within these large settlements, as many individuals may have been derived from the “urban periphery” (goodman, 2007:1-2), or represent rural migrants (griffin and pitts, 2012; redfern et al., 2015). materials dental caries was recorded in 433 non-adults (aged 1.1-17.0 years) and a total of 6,283 erupted teeth (deciduous n=2910; permanent n=3373) from 15 romano-british sites dating from the 1st-5th centuries ad (table 1, figure 1). infants (birth to 1.0 year) were excluded from analysis due to the scarcity of erupted teeth within this age group. the following age categories defined by lewis (2002) were used: 1.1-2.5 years, 2.6-6.5 years, 6.6-10.5 years, 10.6-14.5 years, 14.6-17.0 years. age ranges serve to minimise age estimation error, and allow for cross-site comparison while corresponding with developmental milestones (lampl and johnston, 1996; scheuer and black, 2004; lewis, 2010). methods individuals were aged based on their dental development either through macroscopic assessment or, wherever possible, using radiographs (moorres et al., 1963a,b). as non-adults were not sexed, male and fesite date (ad) type total non -adults tpr by tooth count a/p (%) cpr by individual a/p (%) reference winchester (north, west, east) 1-4th century major urban 39 11/559 (2.0) 6/39 (15.4) ottaway et al. (2012) kingsholm, gloucester 2-4th century major urban 9 9/135 (6.7) 4/9 (44.4) hurst (1985), (1986) gambier-parry lodge, gloucester 2-4th century major urban 6 0/76 (0.0) 0/6 (0.0) heighway (1980); mullin (2006) trentholme drive, york 3-4th century major urban 17 2/262 (0.8) 2/17 (11.8) wenham (1968); ottaway (2009) bath gate, cirencester 4th century major urban 38 5/483 (1.0) 4/38 (10.5) viner and leech (1982) butt road, colchester 4-5th century major urban 80 22/1209 (1.8) 12/80 (15.0) crummy and crossan (1993) baldock, hertfordshire 2-4th century minor urban 25 2/414 (0.5) 2/25 (8.0) stead and rigby (1986); burleigh and fitzpatrickmatthews (2010) queenford farm/ mill, oxfordshire 3-4th century minor urban 51 8/729 (1.1) 3/51 (5.9) durham and rowley (1972); chambers (1987) ancaster, lincolnshire 3-4th century minor urban 34 13/480 (2.7) 5/34 (14.7) todd (1975); cox (1989) great casterton, rutland 3-4th century minor urban 27 7/383 (1.8) 4/27 (14.8) mcconnell et al. (2012) ashton, northamptonshire 4th century minor urban 17 0/265 (0.0) 0/17 (0.0) dix (1983) dunstable, bedfordshire 3-5th century minor urban 12 7/201 (3.5) 4/12 (33.3) matthews (1981) owslebury, hampshire 1-4th century rural 3 0/42 (0.0) 0/3 (0.0) collis (1968), (1977) cannington, somerset 3-4th century rural 69 4/977 (0.4) 3/69 (4.3) rahtz et al. (2000) catsgore, somerset 2-5th century rural 1 0/6 (0.0) 0/1 (0.0) leech (1982) bradley hill, somerset 4-5th century rural 5 0/62 (0.0) 0/5 (0.0) leech et al. (1981) total non-adults 433 90/6283 (1.4) 49/433 (11.3) table 1. study sites by settlement date and type 20 dental anthropology 2016 │ volume 29 │ issue 01 male tooth development stages were averaged. the cut -off point of 17.0 years was assigned when the roots of the third mandibular molar were complete but the apex remained open, giving an average age of 16.9 years old (smith, 1991). when the apices of the available teeth were closed, an upper age estimate was derived using skeletal maturation and diaphyseal lengths (ubelaker, 1989; scheuer and black, 2000; 2004). individuals were excluded once the femoral head was fully fused, with completion estimated between 14-17 years in females and 16-19 years for males (scheuer and black, 2000; 2004). it is recognised that the cut-off age of 17.0 years reflects a biological rather than chronological age; however, it is based on the oldest, most accurate age estimate we currently have for non-adults (lampl and johnston, 1996). it is of course recognized that a biological age of 17.0 years would not necessarily have marked the end of childhood in roman britain. the lifecourse of romano-british children is not fully explored; we therefore cannot use skeletal ages or age groups according to chronological ages that marked transitions in the lifecourse we are yet to define. only erupted teeth were included in the analysis, reflecting their susceptibility to dental caries. for teeth within the jaw, eruption was defined as those teeth in occlusion. the identification of loose teeth as erupted involved an assessment of root development stages (moorrees et al., 1963a,b) and eruption patterns (ubelaker, 1989), in addition to any evidence of wear or dental calculus (buikstra and ubelaker, 1994). as different teeth have varying degrees of susceptibility to dental caries, they were defined by type: deciduous or permanent, posterior (deciduous and permanent molars, permanent premolars) or anterior (deciduous and permanent incisors and canines) and location (i.e. root or crown). carious lesion frequencies were reported accordingly. a lesion was recorded macroscopically when it perforated the tooth enamel. statistical analysis was performed using a pearson’s chi-square test to evaluate the prevalence of lesions between the urban and rural sites, with a confidence limit set at 99.5% (p=0.005). percent caries rates are presented as both crude prevalence rates (cpr) for the number of individuals observed and affected, or more precisely as true prevalence rates (tpr) determined by the number of teeth observed over those affected. the caries correction factor advocated by lukacs (1995) was not applied as antemortem tooth loss is low in non-adult samples and loss of teeth through attrition was unlikely. enamel hypoplasia was recorded macroscopically when the tooth enamel was disrupted by circular or linear defects on two or more teeth on opposite sides of the dentition (goodman and armelagos, 1985; goodman and rose, 1990). this was done to avoid recording defects that may have resulted from localised trauma. the relationship between enamel hypoplasia and caries was quantified by yule’s q. results entire sample the prevalence of dental caries for each site is listed in table 1. for all sites and in the deciduous and permanent dentition combined, 11.3% (n=49/433) of individuals displayed caries, with a tpr of 1.4% (n=90/6283 teeth). overall, 2.1% of posterior teeth were affected (n=79/3678 teeth) compared to only 0.1% (n=2/2586 teeth) of the anterior teeth, a significant difference (x²=51.29, p<0.001, d.f.=1). no lesions at the cemento-enamel junction (or ‘root caries’) were reported. carious lesions were predominantly found on the occlusal surface of posterior teeth (tpr 1.1%, n=39/3678 teeth). fissure caries accounted for 49.4% (n=39/79 teeth) of lesions in posterior teeth. when the deciduous and permanent caries rates were compared, tpr was marginally higher in the deciduous dentition at 1.5% compared to 1.1%, but not significantly so (x²=1.58, d.f.=2) (table 2). inter-settlement comparisons nine carious teeth in the minor urban cohort were derived from the ancaster toddler with secc (bonsall et al., 2015). to prevent skewing of the data, this individual was removed from analysis. the prevalence of figure 1. distribution of study sites (black: major urban, dark grey: minor urban, light grey: rural) 21 dental anthropology 2016 │ volume 29 │ issue 01 caries was highest in the major urban sites (cpr 14.8%, tpr 1.8%), followed by minor urban (cpr 10.3%, tpr 1.1%) and rural settlements (cpr 3.8%, tpr 0.3%). the rural tpr is significantly lower than those reported from the urban settlements (x²=13.66, p<0.005, d.f.=2). lesion frequency in posterior teeth was significantly lower in the rural sites at tpr 0.6% (n=4/659 teeth; x²=12.34, p<0.005, d.f.=2) compared to both the major and minor urban sites. lesions in the anterior dentition were only found in two non-adults, both from a major urban site, affecting the deciduous canine in the maxillary dentition of a 2.6-6.5-year old from kingsholm, gloucester, and the mandibular deciduous canine of a 6.6-10.5-year old from the northern cemetery at winchester (see table 2). in the deciduous teeth, significantly more lesions were recorded in the major urban cohort (n=32/1075 teeth) at tpr 3.0% (x²=27.03, p<0.001, d.f.=2). whereas no significant differences were observed for caries in the permanent teeth (see table 2). interproximal caries affecting the crown surface, either mesially or distally, was observed in 29 posterior teeth or 1.0% of the total sample (n=29/3019 teeth), but only in the major and minor urban sites with a revised prevalence rate of 38.7% (n=29/75 teeth). again, buccal caries was only observed in these urban cohorts with a prevalence of 10.7% (n=8/75 teeth). age differences the prevalence of caries increased with age, albeit with a slight decrease in the 10.6-14.5 year age group (cpr 16.7%, tpr 1.3%), probably as a result of the shedding of the primary dentition. caries was not apparent until 10.6 years in the rural sample, whereas lesions were observed in the youngest cohort (1.1-2.5 years) in the major urban sample. in the 6.6-10.5-year cohort, the frequency of carious lesions was statistically higher in the major urban sample at tpr 3.7% (n=20/539 teeth; x²=11.36, p<0.005, d.f.=2) compared to both the minor urban and rural sites. out of the total of 20 carious teeth within this major urban group, 17 (85.0%) were deciduous molars (table 3). stress and caries in the major urban group, 11.4% of teeth (n=309/2700 teeth) had dental enamel defects, compared to 9.6% (n=236/2460 teeth) in the minor urban cohort, and 4.5% (n= 49/1087 teeth) in the rural sample. the rural rate was significantly lower than those from both urban contexts (x²=43.66, p<0.001, d.f.=2). the higher rates of enamel hypoplasia observed in major urban non-adults (tpr 11.4%) also matched the elevated rates of caries in these settlements. overall, 39.6% (n=19/48) of the children with caries also had enamel hypoplasia. the yule’s q statistic of 0.75 indicates that a moderate to strong relationship between the two conditions existed. this co-occurrence was highest in major urban sites at 5.8% (n=11/189) and lowest in rural children at 1.3% (n=1/78), although these differences were not significant (x²=3.26, d.f.=2) (table 4). major urban minor urban rural total tth ind tth ind tth ind tth ind a/p 49/2724 28/189 28/2453* (37/2472) 17/165* (18/166) 4/1087 3/78 81/6264* (90/6283) 48/432* (49/433) total % 1.8 14.8 1.5* (1.5) 10.3* (10.4) 0.3 3.8 1.3* (1.4) 11.1* (11.3) deciduous teeth a/p 32/1075 14/125 10/1335 7/127 1/481 1/54 43/2891 22/306 % 3.0 11.2 0.7 5.6 0.2 1.9 1.5 7.2 permanent teeth a/p 17/1649 14/124 18/1118 10/86 3/606 2/43 38/3373 26/253 % 1.0 11.3 1.6 11.6 0.5 4.7 1.1 10.3 anterior teeth a/p 2/1100 2/171 0/1058 0/152 0/428 0/69 2/2586 2/392 % 0.2 1.2 0 0 0 0 0.08 0.5 posterior teeth a/p 47/1624 28/185 28/1395 17/164 4/659 3/78 79/3678 48/427 % 2.9 15.1 2.0 10.4 0.6 3.8 2.1 11.2 tth = tooth count; ind=individual count; a/p = number affected/number present; *corrected rates for the ancaster child with secc, uncorrected rates in brackets table 2. carious lesion frequencies by tooth type and individual 22 dental anthropology 2016 │ volume 29 │ issue 01 discussion this study provides the first large-scale examination of carious lesion frequencies in non-adults from urban and rural settlements in roman britain. dental caries is age-progressive and multifactorial, but can provide valuable insights into the cultural habits that affected non-adult diet, particularly where the characteristics of eating and drinking in childhood across roman britain are still largely unknown. this study is limited by the scarcity of skeletal and dental material from rural sites, a common problem within romanobritish bioarchaeology, and due to limited sample sizes it was also not possible to analyse variations in diet over time. however, caries affected 11.3% of the romanobritish children, or 1.4% of all erupted teeth. lesions were more frequent in children from major urban sites, where 14.8% of non-adults presented with caries. this is substantially higher than the non-adult rate reported at the dorchester civitas (cpr 3.6%, lewis pers. comm.), which is thought to represent a major urban settlement. instead, the dorchester rates are more comparable to the rural pattern (cpr 3.8%) (see table 2, table 5). the major urban tpr of 1.8% is, however, similar to that reported from the lankhills cemetery for the winchester civitas (tpr 1.7%) (clough and boyle, 2010). when the deciduous teeth were examined, lesions were statistically more frequent in the major urban sample (tpr 3.0%), the only cohort to show individuals with caries in the anterior deciduous dentition. higher rates of lesions in the deciduous compared to permanent dentition might be expected due to reduced enamel hardness and longer exposure to the oral environment (hunter et al., 2000; halcrow et al., 2013), although soft and carbohydrate-rich weaning foods further elevate early childhood caries (temkin, 1991; garnsey, 1999). hence, the greater frequencies of deciduous caries in the major urban group suggest a prolonged exposure to cariogenic foods during early childhood (veerkamp and weerheijm, 1995; berkowitz, 2003; freeman and stevens, 2008), while the presence of anterior deciduous caries may hint at the use of pacifiers (azevedo et al., 2005). the significantly lower rate of deciduous caries in the rural settlements suggests a different early childhood diet or major urban minor urban rural total tth ind tth ind tth ind tth ind total a/p 309/2700 54/214 236/2460 43/192 49/1087 12/105 594/6247 109/511 % 11.4 25.2 9.6 22.4 4.5 11.4 9.5 21.3 comorbidity a/p 11/189 7/165 1/78 19/432 % 5.8 4.2 1.3 4.4 tth = tooth count; ind=individual count; a/p = number affected/number present table 4. prevalence rates of enamel hypoplasia and co-morbidity major urban minor urban rural total age (years) tth ind tth ind tth ind tth ind 1.1-2.5 a/p 1/394 1/38 0/571 0/49 0/193 0/21 1/1158 1/108 % 0.3 2.6 0.0 0.0 0.0 0.0 0.1 0.9 2.6-6.5 a/p 12/555 7/50 7/774 4/56 0/254 0/22 19/1583 11/128 % 2.2 14.0 0.9 7.1 0.0 0.0 1.2 8.6 6.6-10.5 a/p 20/539 8/35 4/393 4/27 0/112 0/8 24/1044 12/70 % 3.7 22.9 1.0 14.8 0.0 0.0 2.3 17.1 10.6-14.5 a/p 11/883 8/44 11/520 5/25 1/315 1/15 23/1718 14/84 % 1.3 18.2 2.1 20.0 0.3 6.7 1.3 16.7 14.6-17.0 a/p 5/213 4/20 6/195 4/8 3/351 2/12 14/759 10/40 % 2.4 20.0 3.1 50.0 0.9 16.7 1.8 25.0 tth = tooth count; ind=individual count; a/p= number affected/number present table 3. carious lesion frequencies by age group and site type 23 dental anthropology 2016 │ volume 29 │ issue 01 food processing techniques. fewer carious lesions in the rural cohort may suggest that this part of the population was restricted in its consumption of agricultural products, which are high in carbohydrates. perhaps this reflects the primary role of rural inhabitants in this period, who were expected to produce a surplus to provide for urban dwellers, the army, and the elite (de la bédoyère 1993, 86; jones 1996, 208; macmullen 1987; whittaker and garnsey 1997), where rural families would have been hesitant to consume their primary source of income. in turn, rural weaning foods may have been chosen that were less economically important and also less cariogenic. differences in the archaeobotanical record between rural sites, particularly in the southwest where the sample sites of the current study are located, and urban settlements across roman britain were observed by van der veen and colleagues (2008), and strengthen the argument for biased food allocation between producer and consumer. a diet high in grit, with hard and abrasive fibrous foods or contaminants may have also been consumed in rural areas, limiting dental caries development (duray, 1992; moynihan, 2000). further research into dental wear in the urban and rural groups may help elucidate this pattern. while it is important to compare the results from this study with those that have gone before, this is challenging. many of the studies that have discussed caries rates in romano-british nonadults have very small sample sizes, and merged data without specifying which sites they included (table 5). however, data for carious lesion frequency in non-adults is available for rome itself. killgrove (2010) reported true prevalence rates for 0-10 year olds, and 11-20 year olds. at casal bertone, a cemetery located close to the walls of the city of rome, caries prevalence rates were 3.2% (010 year olds) and 2.9% (11-20 year olds), compared to 2.2% (n=33/1488 teeth in 1.1-10.5 year olds) and 1.5% (n=16/1096 teeth in 10.6-17.0 year olds) in the major urban cohort of the current study. lesions were less frequent at the cemetery at castellia europarco which was located in an agricultural area of the suburbs of rome. just as in this study, no dental caries was reported in children under 10 years old; however, the sample was small (n=2/121 teeth) (killgrove 2010). although we cannot make inferences on the specific foods eaten in rome and the major urban towns of roman britain from this comparison, dental disease rates from both locations highlight the pertinent differences in oral health between residents of the towns and country at the centre and the fringes of the empire. prowse and colleagues (2008) reported a tpr of 3.8% for carious lesions in the deciduous teeth of 1-12 year olds from the necropolis at isola sacra at urban portus. although the deciduous caries rates for major urban settlements (3.0%) in the current study are significantly higher than elsewhere in roman britain, it is below that of children living in italy, even outside of rome. additional data for child caries rates comes from kellis ii in egypt, where shukrum and molto (2009) reported a tpr of 8.9% for deciduous teeth and tpr 3.8% for the permanent dentition, again substantially higher than seen in the british province. overall, refined carbohydrates and a more fortified diet may have been study site and context date (ad) cpr (%) tpr (%) comments moore and corbett (1973) various unknown major urban, military 1st-5th century 4.2 deciduous teeth o’sullivan et al. (1993) various unknown not stated 1st-5th century 16.0 deciduous molars redfern et al. (2012) various (dorset) major urban, rural 1st-5th century 0.3/1.5 deciduous/ permanent teeth lewis (pers. comm.) poundbury camp dorchester civitas 3rd-5th century 3.6 0.7/0.7 deciduous/ permanent teeth clough and boyle (2010) lankhills winchester civitas 4th century 1.7 deciduous and permanent teeth caffell (2007) horncastle, lincolnshire, fort/minor urban 4th century 12.5/0.0 deciduous/ permanent teeth table 5. previously reported caries rates in romano-british non-adults 24 dental anthropology 2016 │ volume 29 │ issue 01 more readily available to major urban residents in roman britain, compared to those living in the countryside. yet, access to rich foods was more restricted than in rome, the italian urban centres and other provinces closer to the centre of the empire. however, we also have to assume that genetic and geographic factors, such as immunity and fluoride exposure may have influenced dental caries susceptibility between these different populations. although the exact pathophysiology of a relationship between enamel hypoplasia and carious lesion development remains to be explored, a total of 39.6% of children with carious lesions also displayed dental enamel hypoplasia. the result was anticipated, and is consistent with the cariespromoting function of stress. stress may have elevated salivary cortisol levels, which in turn suppressed salivary iga and enabled cariogenic bacteria to spread (boyce et al., 2010). not only will these children have experienced a greater spread of cariogenic bacteria, but the quality of hypoplastic teeth would have exacerbated this effect. in the affected children, bacteria adhere to the site of the defect, and the thinned or defective enamel is more acid soluble, both allowing for dental caries to progress quicker (hong et al., 2009). co-occurrence of caries and enamel defects was more frequent in the urban cohorts. more bacteria in the oral cavity, and thinned enamel as a result of non-specific stress may have contributed to the progression of caries in those children. since hypoplastic enamel defects were more frequent in the major urban cohort than in the rural children, both diet and non-specific stress may have contributed to the significant differences in carious lesion frequencies. this would suggest that higher status of the major urban children was not necessarily a given. the youngest individual reported with carious lesions was a 1.1-2.5-year old from butt road, colchester with occlusal carious lesions on the deciduous maxillary second molar. the rise in caries tprs from the youngest age group may reflect the timing of colonisation of the oral cavity with s. mutans. carious lesions usually appear between 13-16 months after initial colonisation (kawashita et al., 2011), suggesting the children in this study were affected at around one year of age. however, the administration of cariogenic foods and feeding habits may have occurred earlier, for instance between 6-12 months when infants start to sit up, develop better chewing and tasting mechanisms, and are eventually able to self-feed (sheridan, 1991; sellen, 2001; 2007; carruth and skinner, 2002; delaney and arvedson, 2008). neither human breastmilk nor cow’s milk are very cariogenic, but their caries-promoting properties are significantly increased when the infant is fed supplementary foods rich in carbohydrates such as fruits and honey (moynihan, 2000; azevedo et al., 2005; kawashita et al., 2011). today, s. mutans is mainly transmitted from the primary caregiver to the infant as soon as tooth surfaces have erupted (gussy et al., 2006). in rome, early child care was not only provided by the mother, but also by a nutrix or paedagogus among richer families (mcwilliam, 2013), or by neighbours, friends and relatives for working women (rawson, 2003a; golden, 2011). it is likely similar practices were in place in britain. for example, caries rates in romano-british females are reported as 5.4% at cannington (brothwell et al., 2000), 3.9% at butt road, colchester (pinterbellows, 1993), and 5.4% at bath gate, cirencester (wells, 1982), higher than those observed in the non-adults from the same sites (tprs of 0.4%, 1.8% and 1.0% respectively). the mechanism of s. mutans transmission may show that romano-british care givers pre-chewed or tasted their infants’ food, and shared utensils with them when administering food or drink (fildes, 1986). historical evidence for pre-mastication refers to it as a practice to be avoided (bradley, 1986; temkin, 1991), which indicates that it might have indeed occurred, and probably had an influence on the transmission of oral infections from caregiver to child. lesion frequencies were higher in major urban and minor urban children from 10.6-17.0 years, at almost four times the rate reported for the rural sites. it is possible that this pattern is reflecting a richer diet of fortified foods for these adolescents. the fact that the majority of carious lesions in both the major urban and minor urban samples were interproximal and occlusal further attests to a softer and more refined diet (vodanović et al., 2005). there is archaeological evidence for the fine milling of cereals into white flour (cool, 2006; alcock, 2010) and following a roman diet, refined sugar may have been accessed in the form of honey and syrups (moore and corbett, 1973; bowman and thomas, 1994; cool, 2006; carreck, 2008; crane, 2013). honey has antibacterial properties which inhibit s. mutans growth, but whether honey is primarily cariogenic or cario-protective is debatable (bogdanov et al., 2008; nassar et al., 2012). however, it would have been the main sweetener in this time period and therefore frequently consumed. grape syrup known as defrutum, sapa or caroenum was made in spain or southern gaul and was shipped to britain in distinctive amphorae (cool, 25 dental anthropology 2016 │ volume 29 │ issue 01 2006). evidence for these amphorae in britain is scarce and dates mainly to the 1st and 2nd centuries ad. these syrups were therefore either imported in different vessels in the later centuries, became even more difficult to get hold of or, alternatively, ceased to be available in roman britain (sealey and davies, 1984; sealey and tyers, 1989; monfort, 1998). however, defrutum could be made from boiling down any fruit juice in lead vessels, and would therefore have been widely available across roman britain (farwell and molleson, 1993; roberts and cox, 2003). in summary, carious lesion frequencies in children aged older than 10.6 years attest to dietary differences between those living in the towns and country, probably linked with the availability of more refined and softer foods in the urban centres. conclusions this research has demonstrated the value of reporting carious lesion frequency in non-adults. its use is further increased by considering the location and type of carious lesions, and the presence of early childhood stress. higher rates of dental disease in urban environments suggest differences in diet between children in the countryside and the towns of britannia. elevated stress, measured as the prevalence of enamel hypoplasia, in the children growing up in urban settlements was accompanied by higher carious lesion frequency. however, we cannot currently estimate how exact the relationship between stress and enamel defects is to the incidence and severity of dental caries. carious lesions in the deciduous dentition allow for inferences to be made on weaning and feeding practices that promote dental decay, such as the sharing of utensils and food between caregiver and child. the lower frequency of carious lesions in the rural sample suggests a simpler diet consumed by these children, possibly as a result of biased food allocation in response to economic pressures. urban populations may have had more access to processed and sweetened foodstuffs whereby refined carbohydrates were more readily available. acknowledgments this research was funded by an ahrc phd studentship. we thank the curators who provided access to the skeletal collections for this project: robert kruszynski, natural history museum london; keith fitzpatrick-matthews, north hertfordshire district council museums service; simon mays, english heritage; christiane jeuckens, oxfordshire museums service; jo buckberry, biological anthropology research centre; steve minnitt, somerset heritage centre; david allen, hampshire arts and museums service; sarah wilson, peterborough museum; helen rees, winchester museum service; lorraine cornwell, rutland county museum; alison brooks and heather dawson, corinium museum; paul sealey, colchester and ipswich museums and timothy vickers, luton culture. the authors thanks the anonymous reviewers and editor for their constructive comments which have greatly improved an earlier draft of this paper. literature cited afroughi s, faghihzadeh s, khaledi mj, motlagh mg. 2010. dental caries 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o’sullivan ea, williams sa, wakefield rc, cape je and curzon mej. 1993. prevalence and site characteristics of dental caries in primary molar teeth from prehistoric times to the 18th century in england. caries res 27: 147-153. ottaway p. 2009. roman york. stroud: the history press. ottaway pj, qualmann ke, rees h, scobie gd. 2012. the roman cemeteries and suburbs of winchester – excavations 1971-86. winchester: winchester museums and english heritage. parkins hm. 1997. the “consumer city” domesticated? the roman city in elite economic strategies. in: parkins hm, ed. roman urbanism – beyond the consumer city. london: routledge. p 83-111. pearce j. 2008. burial evidence from roman britain – the un-numbered dead. pour une archaéologie du rite. nouvelles perspectives de l'archaéologie funéraire, études réunies par john scheid. paris: collection de l'ecole francaise de rome. p 2942. pitts m, griffin r. 2012. exploring health and social well-being in late roman britain: an intercemetery approach. am j archaeol 116(2): 253-276. pitts m, perring d. 2006. the making of britain’s first urban landscapes: the case of late iron age and roman essex. britannia 37: 189-212. powell ml. 1985. the analysis of dental wear and caries for dietary reconstruction. in: gilbert ri, mielke jh, eds. the analysis of prehistoric diets. orlando: academic press. p 307-388. powell la, redfern rc, millard ar, gröcke dr. 2014. infant feeding practices in roman london: evidence from isotopic analyses. in: carroll m, graham e, eds. infant health and death in roman italy and beyond. portsmouth: j roman archaeol supplementary series 96. p 89-110. prowse tl. 2011. diet and dental health through the life course in roman italy. in: agarwal sc, glencross ba, eds. social bioarchaeology. oxford: blackwell studies in global archaeology 15. p 410-437. prowse tl, saunders sr, schwarcz hp, garnsey p, macchiarelli r, bondioli l. 2008. isotopic and dental evidence for infant and young child feeding practices in an imperial roman skeletal sample. am j phys anthropol 137: 294-308. rahtz p, hirst s, wright sm. 2000. cannington cemetery – excavations 1962-3 of prehistoric, roman, post-roman, and later features at cannington park quarry, near bridgwater, somerset. london: society for the promotion of roman studies, britannia monograph series 17. rawson b. 1966. family life among the lower classes at rome in the first two centuries of the empire. class philol 61(2): 71-83. rawson b. 1986a. children in the roman familia. in: rawson b, ed. the family in ancient rome – new perspectives. london: routledge. p 170200. rawson b. 1986b. the roman family. in: rawson b, ed. the family in ancient rome – new perspectives. london: routledge. p 1-57. rawson b. 1991a. adult-child relationships in roman society. in: rawson b, ed. marriage, divorce and children in ancient rome. oxford: oxford university press. p 7-30. rawson b. 1991b. marriage, divorce and children in ancient rome. oxford: clarendon press. rawson 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rethinking change and decline. cambridge: cambridge university press. rogers b, arvedson j. 2005. assessment of infant oral sensorimotor and swallowing function. ment retard dev d r 11(1): 74-82. 31 dental anthropology 2016 │ volume 29 │ issue 01 rosenthal r. 1936. a short pictorial review of the evolution of infant-feeding vessels up to the beginning of the 19th century. bull med libr assoc 25(1-2): 89-94. rutgers l v, van strydonck m, boudin m and van der linde c, 2009. stable isotope data from the early christian catacombs of ancient rome: new insights into the dietary habits of rome’s early christians. j archaeol sci 36, 1127-1134 saller r. 1991. corporal punishment, authority and obedience in the roman household. in: rawson b, ed. marriage, divorce and children in ancient rome. oxford: oxford university press. p 144-165. scheuer l, black s. 2000. developmental juvenile osteology. san diego: academic press. scheuer l, black s. 2004. the juvenile skeleton. london: elsevier academic press. schuurs a. 2013. pathology of the hard dental tissues. chichester: wiley-blackwell. schwartz jh. 2007. skeleton keys – an introduction to human skeletal morphology, development and analysis (2nd edition). oxford: oxford university press. sealey pr, davies gmr. 1984. falernian wine at roman colchester. britannia 15: 250-254. sealey pr, tyers pa. 1989. olives from roman spain: a unique amphora find in british waters. antiq journ 69(1): 53-72. sellen d w. 2001. comparison of infant feeding patterns reported for nonindustrial populations with current recommendations. j nutr 131: 2707-2715. sellen dw. 2007. evolution of infant and young child feeding: implications for contemporary public health. annu rev nutr 27: 123-148. sheridan md. 1991. from birth to five years. routledge: routledge. shukrum s, molto j. 2009. childhood oral health: dental pathology of kellis ii, dakhleh, egypt. in: lewis m, clegg m, eds. proceedings of the 9th conference of the british association for biological anthropology and osteoarchaeology. oxford: archaeopress. p 19-30. sigismund-nielsen h. 2007. children for profit and pleasure. in: harlow m, laurence r, eds. age and ageing in the roman empire. portsmouth: j roman archael supplementary series 65. p 37-54. smith bh. 1991. standards of human tooth formation and dental age assessment. in: kelley ma, larsen cs, eds. advances in dental anthropology. new york: wiley liss. p 143-168. sreebny lm. 1983. sugar and human dental caries. world rev nutr diet 40: 19-65. stead im, rigby v. 1986. baldock: the excavation of a roman and pre-roman settlement, 1968-72. london: society for the promotion of roman studies. taylor j. 2001. rural society in roman britain. in: james s, millett m, eds. britons and romans: advancing an archaeological agenda. york: cba research report 125. p 46-59. temkin o. 1991. soranus’ gynecology. baltimore: johns hopkins university press. todd m. 1975. margidunum and ancaster. in: rodwell w, rowley t, eds. the ‘small towns’ of roman britain. oxford: bar british series 15. p 211-224. touger-decker r, van loveren c. 2003. sugars and dental caries. am j clin nutr 78(4): 881-892. ubelaker dh. 1989. human skeletal remains: excavation, analysis, interpretation (2nd edition). washington: taraxacum. van der veen m. 2008. food as embodied material culture: diversity and change in plant food consumption in roman britain. j roman archaeol 21: 83-109. van der veen m, livarda a, hill a. 2007. the archaeobotany of roman britain: current state and identification of research priorities. britannia 38: 181-210. van der veen m, livarda a, hill a. 2008. new plant foods in roman britain: dispersal and social access. environ archaeol 13: 11-36. veerkamp jsj, weerheijm kl. 1995. nursing-bottle caries: the importance of a developmental perspective. j dent child 62(6): 381-386. viner l, leech r. 1982. bath gate cemetery, 19691976. in: mcwhirr, viner l, wells c. cirencester excavations ii – romano-british cemeteries at cirencester. cirencester: cirencester excavation committee. p 69-133. vodanović m, brkić h, šlaus m, željko d, 2005. the frequency and distribution of caries in the mediaeval population of bijelo brdo in croatia (10th-11th century). arch oral biol 50: 669-680 wacher j. 1974. the towns of roman britain. london: batsford. wenham lp. 1968. the romano-british cemetery at trentholme drive, york. london: ministry of public building and works archaeological reports number 5. white r. 2014. the wroxeter hinterland project: exploring the relationship between country and town. in: breeze dj, ed. the impact of rome on the british countryside. a conference organised by the royal archaeological institute, chester, 11-13 october 2013, london: royal archaeological institute supplementary 15 dental anthropology 2023 │ volume 36│ issue 02 dental anthropology research conducted at the school of dentistry of the universidad del valle (cali, colombia) between 2002 and 2021: a literature review freddy moreno 1.2 * and natalia coriat 1 1 pontificia universidad javeriana cali, colombia 2 school of dentistry of the universidad del valle, colombia at the school of dentistry of universidad del valle (cali, colombia), dental anthropology is considered an interdisciplinary area of knowledge that integrates anthropology, dentistry, biology, paleontology, and paleopathology. the objective is to study all the information provided by human dentition, including anatomical, evolutionary, pathological, cultural and therapeutic variations. this is done by taking into consideration the living conditions, culture, nutrition and adaptation processes of present and past human populations, through the morphology, measurements, diseases, and modifications of the teeth (hillson, 1996; scott & turner, 1997, 1998). in particular, a group of researchers from the aforementioned university has focused their interest on dental metric and nonmetric variations. their approach has allowed for the documentation, analysis, explanation, and understanding of a range of dental phenotypes that can provide insight into the biological relationships among human populations. these dental variations also serve as intergroup markers that facilitate comparative analysis to clarify the history, origin, formation, contact, isolation, and displacement of past and present human groups (alt et al., 1998; rodríguez, 2003, 2004). in colombia, dental anthropology began relatively late compared to other latin american countries, such as mexico and peru. some anthropological and paleontological studies on living populations and archaeological samples had been carried out earlier by researchers such as paul rivet, gonzalo correal, miguel méndez, martin nweeia, edward harris, héctor polanco, and benjamin heraabstract in the last 20 years, the dental anthropology and forensic dentistry research group at the universidad del valle (cali, colombia) has integrated knowledge from anthropology, dentistry, biology, paleontology and paleopathology to characterize the dental morphology of living populations in southwestern colombia. this has been done by studying the frequency and variability of dental morphological features in populations with different ancestries, including euro-descendants, afrodescendants and native americans. the group has employed strategies such as formative research and the creation of cooperative research networks to publish and disseminate their findings on dental morphology mainly within the colombian dental clinical context. however, these studies have been limited in their impact on the international anthropological academic community due to a lack of publication in english and refusals from some specialized journals to publish research on contemporary colombian populations. to address this issue, this article aims to provide a literature review of the research on dental anthropology carried out at the school of dentistry of the universidad del valle (cali, colombia) between 2002 and 2021. despite the high amount of available information, the results of this scientific research have been difficult to make visible, search, access, and recover. *correspondence to: freddy moreno faculty of health sciences at the pontificia universidad javeriana cali (colombia) school of dentistry of the universidad del valle (colombia) email: fmorenog@javerianacali.edu.co keywords: dental morphology, dental complexes, ethnic pattern, biological distances, literature review 16 dental anthropology 2023 │ volume 36│ issue 02 zo, among others. however, the field gained more attention in 1989 with the publication of the “cuaderno de antropología no. 19” of the universidad nacional (bogotá, colombia) entitled "introducción a la antropología dental" by the anthropologist josé vicente rodríguez. this work compiled all available information on the metric and morphological variations of teeth in human populations, drawing mainly from previous research by the institute of ethnology and anthropology of the russian academy of science (moscow, russia) and studies on the origin and diversity of americans carried out by arizona state university. since then, dental anthropology research in colombia has focused on forensic sciences, specifically within the context of forensic anthropology and the study of oral morbidity in pre-hispanic communities. in 1997, alexander zoubov gave a lecture on "la antropología dental y la práctica forense" at the symposium "de lo prehispánico a lo forense: avances de la antropología biológica en colombia," which shifted the research focus towards forensic applications. notable contributions to this field include the work carried out by the expedición humana of the pontificia universidad javeriana (bogotá, colombia), the studies conducted by the laboratorio de antropología física of the universidad nacional by josé vicente rodríguez, the work of the groups antropacífico and antropos under the supervision of anthropologists carlos david rodríguez and miguel eduardo delgado burbano at the departamento de antropología of the universidad del cauca (popayán, colombia), and the studies conducted by the julio césar cubillos museum of the universidad del valle under the historian carlos armando rodríguez (rodríguez, 2003; moreno and moreno, 2007). at the end of the 20th century, research groups focused on dental anthropology were formed in the schools of anthropology of the universidad nacional and the universidad del cauca. however, it wasn't until 2004 that a study group from a school of dentistry, led the dental anthropology and forensic dentistry research group, as was the case with the oral and maxillofacial surgery research group of the school of dentistry of the universidad del valle, whose researchers joined forces to disseminate knowledge from other disciplines that have studied teeth and to apply this information in the dental, anthropological, and forensic contexts. although the study group was inactivated by 2014, the research has continued independently through the work of dentists sandra moreno and freddy moreno (moreno-gómez et al., 2019). to keep research in dental anthropology active, two fundamental strategies were implemented. the first strategy was to establish scientific cooperation alliances with the “laboratorio de antropología física” of the universidad nacional, with the “instituto nacional de medicina legal y ciencias forenses de colombia.” and with the “laboratorio de identificación de la fiscalía general de la nación de colombia.” the second strategy was to use formative research so that dentistry students from different universities in colombia could develop their theses on topics related to dental anthropology, mainly dental measurements and dental morphology. thus, during the last 20 years, a series of studies have been carried out in contemporary populations of southwestern colombia to generate new knowledge on the frequency and variability of non -metric dental traits from research studies, to update the current understanding through literature reviews, to describe the unusual presence of some dental morphological characteristics through case reports, and to encourage critical reading through systematic analysis of the literature (moreno-gómez et al., 2019). the aim of this study is to perform a literature review of the research in dental anthropology conducted at the school of dentistry of the universidad del valle (cali, colombia). due to the lack of available scientific information and the difficulties in searching, accessing, and retrieving scientific research results, it is not possible to objectively quantify the scientific knowledge generated. the literature review is a type of research synthesis that aims to map the literature on a particular topic or research area and identify key concepts and types of evidence generated in the research practice, produced by individuals (researchers), groups (research groups, centers, and institutes), and educational institutions (departments, faculties, and universities) (daudt et al., 2013). materials and methods this study reviewed publications on dental anthropology conducted at the school of dentistry of the universidad del valle (cali, colombia) with the participation of dentistry students from different universities. their theses were advised by researchers affiliated with the dental anthropology and forensic dentistry research group through formative research processes. all populations stud17 dental anthropology 2023 │ volume 36│ issue 02 ied gave their consent to participate and received feedback from the researchers, allowing them to recognize their ethnic origin from the historical processes of colonization in colombia over the last 500 years. specifically, these results have been used in the ethnographic processes of identity construction for community councils of afro-descendant populations and governorates of indigenous communities. the categories used to classify articles and perform the comprehensive review were: article name, year of publication, study type, population studied, sample, journal of publication, country of the journal, language of publication, publisher, thematic context, and number of citations (table 1). results between 2002 and 2021, 44 articles were identified that met the inclusion criteria. therefore, the dental anthropology and forensic dentistry research group published an average of 2.09 articles per year. of these articles, 29 (65.9%) were published in dental journals, including 13 (33.3%) in the revista estomatología, which allowed for the scientific dissemination of the school of dentistry of the universidad del valle. the remaining articles were published in biomedical journals (10.3%), anthropological journals (13.6%), morphological science journals (5.1%), and forensic journals (5.1%). twenty-eight of the journals in which articles were published were edited by public universities (63.6%); five by private universities (11.3%); four by scientific societies (10.3%) and four by private publishers (10.3%). thirty-six articles were published in spanish (81.8%), five in english (11.3%), and three in both languages (7.69%). all 44 articles implemented the keyword dental anthropology (100%), 38 implemented dental morphology (86.3%), four implemented dental measurements (9.09%), 13 implemented forensic anthropology (30.2%), 12 implemented dental identification (27.2%), and three implemented radiology (7.7%). twelve of the journals in which the articles were published are indexed in medline (30.8%), 17 in doaj (38.6%), 23 in latindex (52.2%), 11 in scielo (28.2%), and 31 in national (colombia) and regional (latin america) indexes (79.5%). thirty-four of these articles have been cited from google scholar (87.1%), six articles from publons (2.34%), and five from scopus (1.95%). the articles were derived from 23 undergraduate degree works, one undergraduate degree work in pediatric dentistry, and one master's degree work in criminalistics. fourteen articles were derived from research processes carried out by professors as part of their scientific activities. the 39 articles included a total of 90 dentistry students (2.6 students per study) and six graduate students. likewise, 78 participations of professors were observed with an average of 2.2 professors per article. according to the methodological design of the study, 30 articles corresponded to descriptive observational studies (68.1%), 11 articles to literature reviews (25%), and four articles to case reports (9.09%). regarding the thematic area, 36 articles corresponded to dental morphology (81.8%), four articles to dental measurements (9.09%), three articles to dental eruption (7.7%), one article to dental morphology and dimensions (2.6%), and one article to general dental anthropology (2.6%). likewise, and according to the observational method of the sample, 28 articles used plaster models obtained from dental impressions taken of the individuals that made up the sample (63.6%), three used panoramic radiographs (7.7%), five were mainly case reports that used direct observation of the patients (12.8%), and eight did not conduct any type of observational study because they were literature reviews with a purely theoretical approach (18.1%). according to the type of dentition, permanent dentition was studied in 25 articles (56.8%), deciduous and permanent dentition in 16 articles (41.0%), deciduous dentition in two articles (4.5%), and no type of dentition was specified in two articles (5.1%). the most frequently observed teeth were incisors in 22 articles (50%), canines in 10 articles (22.7%), premolars in 19 articles (43.1%), and molars in 31 articles (79.5%). the dental morphological features most frequently observed in the studies were winging in seven articles (17.9%), crowding in six articles (15.4%), shovel-shaped incisors in 13 articles (30.2%), carabelli’s trait in 20 articles (45.4%), hypocone reduction in eight articles (20.5%), protostylid in 20 articles (45.4%), deflecting wrinkle in 13 articles (29.5%), cuspid pattern in 15 articles (34.09%), number of cusps in 10 articles (25.6%), cusp 6 in 12 articles (30.8%), and cusp 7 in 12 articles (30.8%). similarly, other morphological features were observed in canines, premolars, and molars in 17 articles (38.6%). regarding the methods of observation of dental morphological features, asudas (arizona state university dental anthropology system) was used for permanent dentition in 25 articles (56.8%), asudas, hanihara (1961), grine (1986), and sciul18 dental anthropology 2023 │ volume 36│ issue 02 t ab le 1 . s ci en ti fi c ar ti cl es o rg an iz ed b y y ea r of p u bl ic at io n a rt ic le y e a r t y p e o f st u d y p o p u la ti o n st u d ie d s a m p le jo u rn a l c o u n tr y l a n g u a g e p u b li sh e r t h e m a ti c co n te x t g o o g le ci ta ti o n s p u b lo n s c it a ti o n s s co p u s ci ta ti o n s m o re n o & m o re n o 2 0 0 2 l it e ra tu re re v ie w n o n e 0 r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca f o re n si c 2 1 0 0 m o re n o e t a l. 2 0 0 4 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) c o lo m b ia m é d ic a c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 5 5 0 7 m o re n o & m o re n o 2 0 0 5 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d in d ig e n o u s 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) in te rn a ti o n a l jo u rn a l o f d e n ta l a n th ro p o lo g y c o lo m b ia e n g li sh e d it o ri a l p ri v a d a a n th ro p o lo g ic a l 3 4 0 0 r o d rí g u e z & m o re n o 2 0 0 6 c a se r e p o rt m ix e d g ro u p 1 i n d iv id u a l (1 fe m a le ) d e n ta l a n th ro p o lo g y u n it e d s ta te s e n g li sh s o ci e d a d ci e n tí fi ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 2 3 0 0 a g u ir re e t a l. 2 0 0 6 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d in d ig e n o u s 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) d e n ta l a n th ro p o lo g y u n it e d s ta te s e n g li sh s o ci e d a d ci e n tí fi ca a n th ro p o lo g ic a l 5 3 0 0 r o ch a e t a l. 2 0 0 7 d e sc ri p ti v e o b se rv a ti o n a l in d ig e n o u s 8 4 i n d iv id u a ls (4 2 f e m a le s a n d 4 2 m a le s) c o lo m b ia m é d ic a c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 3 6 2 3 a g u ir re e t a l. 2 0 0 7 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) in te rn a ti o n a l jo u rn a l o f d e n ta l a n th ro p o lo g y c o lo m b ia e n g li sh e d it o ri a l p ri v a d a a n th ro p o lo g ic a l 4 0 0 m o re n o & m o re n o 2 0 0 7 l it e ra tu re re v ie w n o n e 0 r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 1 2 0 0 a g u ir re e t a l. 2 0 0 7 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d in d ig e n o u s 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 5 0 0 h e rn á n d e z e t a l. 2 0 0 7 c a se r e p o rt in d ig e n o u s 1 i n d iv id u a l (1 m a le ) r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 2 0 0 a ra g ó n e t a l. 2 0 0 8 d e sc ri p ti v e o b se rv a ti o n a l in d ig e n o u s 9 6 i n d iv id u a ls (4 8 f e m a le s a n d 4 8 m a le s) r e v is ta o d o n to ló g ic a m e x ic a n a m e x ic o s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l a n d f o re n si c 2 9 0 0 g ir ó n e t a l. 2 0 0 9 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 1 1 0 i n d iv id u a ls (4 6 f e m a le s a n d 6 6 m a le s) in te rn a ti o n a l jo u rn a l o f m o rp h o lo g y c h il e s p a n is h u n iv e rs id a d p ri v a d a o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 2 7 0 4 o ca m p o e t a l. 2 0 0 9 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 2 8 5 i n d iv id u a ls (9 7 f e m a le s a n d 1 0 4 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 1 4 0 0 s o to e t a l. 2 0 1 0 l it e ra tu re re v ie w n o n e 0 a ct a o d o n to ló g ic a v e n e z o la n a v e n e z u e la s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 0 0 0 c o rr a l e t a l. 2 0 1 0 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p 1 9 6 i n d iv id u a ls (1 0 9 f e m a le s a n d 8 7 m a le s) c o lo m b ia m é d ic a c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d f o re n si c 3 8 1 4 1 5 19 dental anthropology 2023 │ volume 36│ issue 02 t ab le 1 . s ci en ti fi c ar ti cl es o rg an iz ed b y y ea r of p u bl ic at io n , co n t’ d a rt ic le y e a r t y p e o f st u d y p o p u la ti o n st u d ie d s a m p le jo u rn a l c o u n tr y l a n g u a g e p u b li sh e r t h e m a ti c co n te x t g o o g le ci ta ti o n s p u b lo n s c it a ti o n s s co p u s ci ta ti o n s m o re n o & m o re n o 2 0 1 0 c a se r e p o rt m ix e d g ro u p 1 i n d iv id u a l (1 m a le ) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 9 0 0 h e rn á n d e z e t a l. 2 0 1 0 l it e ra tu re re v ie w in d ig e n o u s 5 i n d iv id u a ls ( 5 m a le s) r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 2 2 3 0 g o y e s e t a l. 2 0 1 1 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d in d ig e n o u s 1 2 2 i n d iv id u a ls (5 9 f e m a le s a n d 6 3 m a le s) r e v is ta c o lo m b ia n a d e in v e st ig a ci ó n e n o d o n to lo g ía c o lo m b ia s p a n is h s o ci e d a d ci e n tí fi ca a n th ro p o lo g ic a l 8 0 0 c a st il lo e t a l. 2 0 1 1 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 6 6 i n d iv id u a ls (2 7 f e m a le s a n d 3 9 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 9 0 0 a co st a e t a l. 2 0 1 1 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 4 8 i n d iv id u a ls (2 4 f e m a le s a n d 2 4 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 1 2 0 0 m a rc o v ic h e t a l. 2 0 1 2 d e sc ri p ti v e o b se rv a ti o n a l a fr o c o lo m b ia n s 1 1 6 i n d iv id u a ls (5 9 f e m a le s a n d 5 7 m a le s) r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h a n d e n g li sh u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 2 6 3 0 p a d il la e t a l. 2 0 1 3 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 1 2 6 i n d iv id u a ls in te rn a ti o n a l jo u rn a l o f m o rp h o lo g y c h il e s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 9 1 0 d ía z e t a l. 2 0 1 4 d e sc ri p ti v e o b se rv a ti o n a l a fr o c o lo m b ia n s a n d in d ig e n o u s 6 0 i n d iv id u a ls (3 5 f e m a le s a n d 2 5 m a le s) c o lo m b ia m é d ic a c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 4 0 6 7 g a rc ía e t a l. 2 0 1 5 d e sc ri p ti v e o b se rv a ti o n a l in d ig e n o u s 6 0 i n d iv id u a ls (3 7 f e m a le s a n d 2 3 m a le s) r e v is ta c o lo m b ia n a d e in v e st ig a ci ó n e n o d o n to lo g ía c o lo m b ia s p a n is h s o ci e d a d ci e n tí fi ca a n th ro p o lo g ic a l 1 0 0 g a rc ía e t a l. 2 0 1 5 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d in d ig e n o u s 6 0 i n d iv id u a ls (3 4 f e m a le s a n d 2 6 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 1 0 0 0 h e rn á n d e z e t a l. 2 0 1 5 l it e ra tu re re v ie w m ix e d g ro u p a n d in d ig e n o u s 0 r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h a n d e n g li sh u n iv e rs id a d p u b li ca o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 6 0 0 p é re z e t a l. 2 0 1 6 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p a n d a fr o c o lo m b ia n s 1 9 5 i n d iv id u a ls (1 0 1 f e m a le s a n d 9 4 m a le s) c u a d e rn o s d e m e d ic in a f o re n se s p a in s p a n is h e d it o ri a l p ri v a d a o d o n to lo g ic a l a n d f o re n si c 4 0 0 20 dental anthropology 2023 │ volume 36│ issue 02 t ab le 1 . s ci en ti fi c ar ti cl es o rg an iz ed b y y ea r of p u bl ic at io n , co n t, ’d a rt ic le y e a r t y p e o f st u d y p o p u la ti o n st u d ie d s a m p le jo u rn a l c o u n tr y l a n g u a g e p u b li sh e r t h e m a ti c co n te x t g o o g le ci ta ti o n s p u b lo n s c it a ti o n s s co p u s ci ta ti o n s m o re n o e t a l. 2 0 1 6 c a se r e p o rt m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 1 i n d iv id u a ls ( 1 m a le ) jo u rn a l o f f o re n si c d e n ta l s ci e n ce s in d ia s p a n is h e d it o ri a l p ri v a d a o d o n to lo g ic a l, a n th ro p o lo g ic a l a n d f o re n si c 3 0 0 m o re n o & m o re n o 2 0 1 6 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 3 8 0 i n d iv id u a ls (2 0 6 f e m a le s a n d 1 7 4 m a le s) r e v is ta c ie n tí fi ca s o ci e d a d d e o rt o d o n ci a c o lo m b ia s p a n is h s o ci e d a d ci e n tí fi ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 0 0 0 m o re n o & m o re n o 2 0 1 6 l it e ra tu re re v ie w n o n e 0 r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 0 0 0 m o re n o & m o re n o 2 0 1 6 l it e ra tu re re v ie w m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 0 r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l a n d f o re n si c 2 0 0 z ú ñ ig a e t a l. 2 0 1 6 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 2 4 e m b e ra ( 1 3 fe m a le s a n d 1 1 m a le s) , 2 7 a fro d e sc e n d ie n te s (1 6 f e m a le s a n d 1 1 m a le s) a n d 3 2 c a u ca so id m ix e d e ti o lo g y (1 8 f e m a le a n d 1 4 m a le s) r e v is ta n a ci o n a l d e o d o n to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p ri v a d a a n th ro p o lo g ic a l 5 0 0 c a rr e ñ o e t a l. 2 0 1 7 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p 3 5 5 i n d iv id u a ls (1 8 1 f e m a le s a n d 1 7 4 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d f o re n si c 4 0 0 p é re z e t a l. 2 0 1 7 d e sc ri p ti v e o b se rv a ti o n a l in d ig e n o u s 1 0 1 i n d iv id u a ls (5 9 f e m a le s a n d 4 2 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 3 0 0 a sp ri ll a e t a l. 2 0 1 7 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 1 0 0 i n d iv id u a ls (5 0 f e m a le s a n d 5 0 m a le s) r e v is ta e st o m a to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l 1 0 0 m o re n o & m o re n o 2 0 1 7 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 3 0 i n d iv id u a ls (1 5 f e m a le s a n d 1 5 m a le s) r e v is ta n a ci o n a l d e o d o n to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p ri v a d a o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 2 0 0 m o re n o & m o re n o 2 0 1 7 l it e ra tu re re v ie w n o n e 0 r e v is ta o d o n to ló g ic a m e x ic a n a m e x ic o s p a n is h u n iv e rs id a d p u b li ca o d o n to lo g ic a l a n d a n th ro p o lo g ic a l 0 0 0 21 dental anthropology 2023 │ volume 36│ issue 02 t ab le 1 . s ci en ti fi c ar ti cl es o rg an iz ed b y y ea r of p u bl ic at io n , co n t’ d a rt ic le y e a r t y p e o f st u d y p o p u la ti o n st u d ie d s a m p le jo u rn a l c o u n tr y l a n g u a g e p u b li sh e r t h e m a ti c co n te x t g o o g le ci ta ti o n s p u b lo n s c it a ti o n s s co p u s ci ta ti o n s p a rr a e t a l. 2 0 1 8 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 4 8 0 i n d iv id u a ls (2 5 7 f e m a le s a n d 2 2 3 m a le s) r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h a n d e n g li sh u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l a n d f o re n si c 0 0 0 g a rc ía e t a l. 2 0 1 8 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 6 0 i n d iv id u a ls (3 7 f e m a le s a n d 2 3 m a le s) r e v is ta n a ci o n a l d e o d o n to lo g ía c o lo m b ia s p a n is h u n iv e rs id a d p ri v a d a a n th ro p o lo g ic a l 0 0 0 m a ri n e t a l. 2 0 2 0 s y st e m a ti c li te ra tu re re v ie w a n d c a se r e p o rt m ix e d g ro u p 1 i n d iv id u a l m a le d e n ta l a n th ro p o lo g y u n it e d s ta te s e n g li sh s o ci e d a d ci e n tí fi ca a n th ro p o lo g ic a l 0 0 0 a m a d o e t a l. 2 0 1 9 d e sc ri p ti v e o b se rv a ti o n a l m ix e d g ro u p , a fr o c o lo m b ia n s a n d i n d ig e n o u s 6 1 3 i n d iv id u a ls (3 4 4 f e m a le s a n d 2 6 9 m a le s) jo u rn a l o d o n to ló g ic o c o le g ia l c o lo m b ia s p a n is h u n iv e rs id a d p ri v a d a o d o n to lo g ic a l 0 0 0 g a rc ía e t a l. 2 0 2 0 d e sc ri p ti v e o b se rv a ti o n a l a fr o c o lo m b ia n s 6 0 i n d iv id u a ls (3 7 f e m a le s a n d 2 3 m a le s) jo u rn a l o d o n to ló g ic o c o le g ia l c o lo m b ia s p a n is h u n iv e rs id a d p ri v a d a o d o n to lo g ic a l 0 0 0 m o re n o & m o re n o 2 0 2 1 l it e ra tu re re v ie w n o n e 0 r e v is ta f a cu lt a d d e o d o n to lo g ía u n iv e rs id a d d e a n ti o q u ia c o lo m b ia s p a n is h a n d e n g li sh u n iv e rs id a d p u b li ca a n th ro p o lo g ic a l a n d f o re n si c 0 0 0 h u rt a d o e t a l. 2 0 2 1 d e sc ri p ti v e o b se rv a ti o n a l in d ig e n o u s 3 0 i n d iv id u a ls (1 6 f e m a le s a n d 1 4 m a le s) ja n g w a p a n a c o lo m b ia s p a n is h u n iv e rs id a d p ú b li ca a n th ro p o lo g ic a l 0 0 0 22 dental anthropology 2023 │ volume 36│ issue 02 li (1998) were used for permanent and deciduous dentition in 11 articles (25%), and asudas, hillson (1996), van reenen et al. (1998), and higa et al. (2003) were used for premolars in three articles (6.8%). one article used powell and humphreys (1984) for dental arch form (2.6%), and three articles used the methods of massler, moorrees et al. (1963), demirjian et al., (1973), and smith (2005) to estimate eruption pattern (7.7%). four articles did not employ any observational method as they were literature reviews (10.3%). finally, one article used manual intercuspal dimensions to determine the area of the occlusal polygon (2.2%). only one article considered dental metric features, meso-distal and buccolingual dimensions, specifically for premolars) (2.6%), using the method of moorrees et al. (1963). the samples included in the studies were defined as mixed populations in 28 articles (63.6%), afro-colombians in 19 articles (43.1%), and indigenous people in 29 articles (65.9%) (figure 1). it is important to mention, according to the discussion by pilloud et al. (2021), that in all the studies carried out, the traditional anthropological nomenclature has prevailed, classifying the studied populations according to their caucasoid, negroid, and mongoloid origin. however, because biological anthropologists are now avoiding these terms, this article uses the terms "asian," "african," and "european" under the category of continental descent. the results of the studies were directed towards dental contexts in 21 articles (47.7%), with 16 of them oriented towards the study of dental anthropology with dental clinical correlation, anthropological in 38 articles (86.3%), and forensic in 14 articles (31.8%). discussion the results obtained will be discussed under four thematic categories: bibliometrics, formative research, methodology implemented, and obtained results. it should be noted that the discussion is not exhaustive due to space limitations and will focus mainly on dental morphology since it has the greatest impact and is the most studied by the dental anthropology and forensic dentistry research group. the review of the categories considered in this study helped to determine that the dental anthropology and forensic dentistry research group has been active since 2002. two research professors initiated the group's activities within a university that lacks a school of anthropology and a school of dentistry that does not offer a specialization in forensic dentistry. their aim was to investigate dental anthropology to broaden and deepen knowledge among dentistry students on dental morphology and its application in other contexts, such as anthropology and forensic dentistry. it is worth highlighting the editorial effort of the colombian anthropologist carlos david rodríguez, who edited and published the international journal of dental anthropology to promote the dissemination of colombian research on topics related to bioarchaeology, paleontology, anthropology, dentistry, and forensic dentistry with an international perspective (rodríguez-flórez, 2005). this is similar to debbie guatelli-steinberg's (2018) description of the dental anthropology newsletter (today dental anthropology) and research in dental anthropology in the context of north american biological anthropology. lópez-lázaro et al. (2016) conducted a systematic review of the literature on non-metric dental traits in current south american populations. they found that remarkable scientific production has figure 1. location of contemporary colombian human populations that have been studied by the research group of dental anthropology and forensic odontology of the universidad del valle. a. choco region (groups of afro-descendants, native americans –embera– and mixed groups); b. valle del cauca region (mixed groups and afro -descendants); c. cauca region (groups of afrodescendants –puerto tejada and villarrica–, native americans –nasa and misak– and caucasoid mixed origin); d. amazon region (groups of indigenous –ticuna, huitoto and cocama–). 23 dental anthropology 2023 │ volume 36│ issue 02 been generated around the study of non-metric dental traits in the last few decades. this study aimed to define the geographical patterns of contemporary south american human groups and to propose the possibility of using the frequency of differential expression traits in the forensic context. the authors identified the revista estomatología (colombia), dental anthropology (united states), and american journal of biological anthropology (united states) as the journals with the most publications (four each), followed by the international journal of morphology (chile) and colombia médica (colombia) with three each. the homo journal of comparative human biology (germany), journal of dental research (united states), human biology (united states), revista de la facultad de odontología de la universidad de antioquía (colombia), and universitas odontologica (colombia) had two publications each. out of the 18 journals identified, six were from colombia, four from the united states, two from germany, and one each from argentina, canada, chile, ireland, mexico, and uruguay. it is noteworthy that seven journals are dedicated to general dentistry, three to general anthropology, two to biology, two to dental anthropology, two to forensic sciences (one of them to forensic dentistry), one to morphology, and one to medicine. however, most articles have been published in dental journals, specifically in the revista estomatología, which is edited by the same academic unit to which the authors belong. this is mainly due to the difficulty that still exists in the colombian environment to publish in english (moreno et al., 2012). despite this, some results were disseminated in anthropological, morphological, and forensic journals, adjusting the focus of the objectives and methodological designs of the studies to include specialized journals whose publication language is english. this includes dental anthropology, edited by the dental anthropology association in the united states, since the scientific genre's standard norm is writing in english, and the international community has limited access to articles written in spanish (ferguson et al., 2011). although the information obtained from the research has been relevant and had some local and regional impact, the results have not gained much visibility in the international community. publishing in english in journals indexed in international directories and using different strategic thematic descriptors, such as dental anthropology, dental morphology, and non-metric dental traits, has contributed to an increase in the number of citations (as measured by the h index of google scholar). the articles published in journals indexed in medline and doaj, which are considered of high impact as they are included in publons and scopus, have achieved the highest number of citations due to their greater visibility (madsen, 2019). this finding is consistent with the results of our analysis, which show that articles published in dental anthropology, colombia médica, and international journal of morphology have received the highest number of citations among articles in english published in international journals. formative research the dental anthropology and forensic dentistry research group, formerly included in the oral and maxillofacial surgery research group of the school of dentistry at universidad del valle, has been operating independently since the group was inactivated in 2014. two research professors have continued the group's work and have found an opportunity to make an academic and scientific impact on the dental field through formative research. the group's focus is mainly on dental morphology and dimensions from the perspective of dental anthropology. a bibliometric analysis of research conducted at the school of dentistry at universidad del valle revealed that topics such as forensic dentistry and dental anthropology, which are not very common in the national dental academic context, have gained relevance in undergraduate dentistry. approximately 100 dentistry students from different universities in southwestern colombia, including universidad del valle, universidad santiago de cali, institución universitaria colegios de colombia, and universidad antonio nariño, have developed 23 undergraduate degree projects resulting in 39 publications (pizarro et al., 2018). in this regard, lópez-lázaro et al. (2016) analyzed the impact of the dental anthropology and forensic dentistry research group. since 2000, the number of publications on dental morphology in different south american countries has been increasing, thanks to the impact of the dental anthropology association and the publication of dental anthropology, as well as the systematization of the observation, registration, and analysis of dental morphological features through asudas. in the specific case of colombia, the work of rodríguez since 1989 and the development of research groups in different colombian schools of anthropology since 2000 marked the beginning of the systematic study of dental anthropology. however, the vast majority of publications have been developed in dental schools, all of them being the product of formative research processes conducted 24 dental anthropology 2023 │ volume 36│ issue 02 by odontologist freddy moreno, in an attempt to raise awareness of the importance of dental anthropology from an anthropological point of view. the expression and variability of dental morphological features can predispose or favor the development of a pathological process, and a correct diagnosis based on the knowledge of the behavior of the feature as an etiological factor is fundamental in dental clinical practice based on preventive, diagnostic, and therapeutic evidence (moreno and moreno, 2007). all this confirms the important presence of publications in journals with a dental profile. however, it is essential to strengthen interdisciplinary work between anthropologists and dentists to solve potentially conflicting methodological competencies when studying dental morphology in individuals in a clinical context (lópez-lázaro et al., 2016). lastly, it is worth highlighting the support provided by professors with diverse specialties who acted as thematic advisors and methodological tutors within the research group of dental anthropology and forensic dentistry. these professors integrated collaborative work in formative research, thus creating a community of interest and a culture of sustainable research over time. this has resulted in the creation of an important network of academic and scientific cooperation, which is composed of dentists, anthropologists, epidemiologists, and statisticians. in this regard, lópezlázaro et al. (2016) stated that the authors of publications on dental morphology in south america mainly have an academic profile in dentistry (57 from colombia, 10 from brazil, eight from chile, six from argentina, three from paraguay and uruguay, two from canada and south africa, and one from venezuela). this is followed by eight geneticists (five of them from chile), three anthropologists (all from colombia), three statisticians, two speech therapists (chile), one archaeologist (united states), and one epidemiologist (colombia). methodology implemented in the studies on dental morphology the impetus created by anthropologist josé vicente rodriguez to the research group of dental anthropology at the universidad del valle since 2000 was not only based on the theoretical deepening of the study of dental morphology in the anthropological and forensic context but also on the methodological foundation of observing and recording the expression and variability of dental morphological traits. the asudas method, proposed by christy g. turner, christian r. nichol, and g. richard scott, and complemented by different authors during the development of new morphological traits, such as van reenen et al. (1998) and higa et al. (2003) or for its application in the deciduous dentition such as hanihara (1961), grine (1986), and sciulli (1998), has been used as an instrument of analysis. however, fonseca et al. (2016) stated that although asudas has globalized the study of dental morphology, its use still does not transcend the boundaries of anthropology, making the system practically unknown in the dental context. lópez-lázaro et al. (2016) also indicated that not all studies carried out by dentists used asudas as a methodological framework, which could eventually make it difficult to compare results globally. according to the same authors, the low usage of asudas could be due to a lack of knowledge of its existence or to the difficulty of use. as of 2006, only 242 sets of plaques had been distributed in 36 countries (more than half distributed in the united states). in south america, the plates were only distributed in physical form in argentina, chile, and brazil. hence, their use has only been possible through internships and collaborations between researchers. on the other hand, there have been reports on morphological features that are considered "unusual" in the dental clinical context (lópezlázaro et al., 2016). since the morphogenetic development of these features is unknown, they are often misdiagnosed as sites prone to the accumulation of bacterial plaque and the development of dental caries or periodontal disease (moreno and moreno, 2007). therefore, beyond anthropological interest and forensic utility, the majority of the studies developed by the research group of dental anthropology and forensic dentistry have had the purpose of expanding the knowledge of dentists about dental morphology through descriptive observational designs, literature reviews, and case reports. for example, there have been efforts to expand the information on different ontological aspects of the dental cingulum, a morphological structure misunderstood by many dentists, and its implications in periodontal disease (moreno and moreno, 2016). there have also been studies to divulge the expression and variability of the protostylid and its controversial point expression in the fossa (p point) during caries diagnosis, as well as the expression of a fossa of carabelli’s trait (hernández et al., 2014; moreno & moreno, 2017). lópez-lázaro et al. (2016) discussed that 19 studies from the research group of dental anthropology and forensic dentistry led by dentist fred25 dental anthropology 2023 │ volume 36│ issue 02 dy moreno made specific mention of the potential use of dental morphological features as forensic identification tools. however, the limitations of using these features for forensic identification have been described by edgar (2009). despite this potential forensic application, the studies on dental anthropology conducted by the research group have primarily had a clinical orientation (lópez-lázaro et al., 2016). obtained results according to scott and turner (1997), just over 100 morphological traits have been identified and described in the crowns and roots of teeth, of which no more than 30 have been widely used for the study of populations due to their high frequency. the majority of observational studies carried out by the research group in dental anthropology and forensic odontology, which described the dental morphology of different populations of southwestern colombia, used ten of these traits. regarding winging and crowding position traits, rodriguez (2003) stated that despite the lack of knowledge of their global variation, these traits have been used to discriminate the sinodonts from the sundadonts within asian populations, which has given them an important value in intragroup comparisons. moreno and moreno (2016) found that, after studying five southwestern colombian populations, the frequency of winging was low, and its variability was characterized by expressions in grade 2 unilateral in afro-descendants from cali and villa rica, and in grade 1 bilateral in afrodescendants from puerto tejada, indigenous nasa, and misak. the frequency of crowding in afrodescendants from cali and villa rica, and in indigenous misak from silvia was observed in a greater expression of grade 1, and in afro-descendants from puerto tejada and the nasa de morales indigenous people, the highest expression was grade 2. another morphological feature that can be observed in anterior teeth is the shovel-shaped incisors, which hanihara (1992) used, along with four other traits, to develop the asian dental complex due to its high frequency in north asian populations. this trait has been useful in differentiating these populations from european and african populations. after turner (1984) studies, it was demonstrated that sinodont groups, which originated in asia, crossed the bering strait and began to populate the american continent, so all prehispanic and contemporary american indians have conserved the ancestral asian condition of shovel-shaped incisors, with expressions of over 80%. rodriguez (2003) has used this trait to discriminate between european populations and asian populations, including amerindians. different studies on colombian indigenous populations have identified high frequencies of the shovelshaped incisor trait in groups that have remained relatively isolated, while the decrease in their expression (grades 1 to 3) could be associated with mixed origin with european and afro-descendant mixed origin groups (rodríguez, 2003; aragón et al., 2008; díaz et al., 2014). one of the most interesting traits to study in contemporary colombian populations is carabelli’s trait, which is considered a european trait with great discriminating power between mixed, afrocolombian, and indigenous colombian groups. however, through different studies, it has been possible to understand that the dichotomous expression (absence/presence) of the asudas reference plaque should not be associated with ethnically mixed origin (aragón et al., 2008; díaz et al., 2014, zúñiga et al., 2016), due to the fact that indigenous colombian populations have been characterized by presenting fossa expressions in intermediate degrees, which are considered present in the gradation, so they have been recognized as a characteristic pattern of all amerindians (rodríguez, 2003). in a study that grouped different contemporary populations of southwestern colombia, it was found that mixed groups presented fossa expressions, y depressions, and small cusps. afrodescendant groups had the expression of medium and large cusps with free vertex. indigenous groups had pit expressions. nevertheless, the authors observed that the ethnic groups mentioned were not grouped according to the three established dental complexes because carabelli’s trait did not constitute itself as an ethnic discriminator. this conclusion was associated with the mixed origin of the populations of southwestern colombia given the tendency of the mixed population of cali, the afro-descendants of puerto tejada and the nasa indigenous people to group with asian populations (pit shape expressions), while the afro -descendants of villarica, guapi, and tumaco did so with european populations (cuspid expression) (moreno and moreno, 2017). the behavior of carabelli’s trait contrasts with the hypocone reduction because the worldwide expression of this trait varies from 13% in european to 95% in asian populations, according to rodriguez (2003). in colombian populations, regardless of the ethnic component, the tendency has 26 dental anthropology 2023 │ volume 36│ issue 02 been to maintain the size of the distolingual cusp from the first upper molar towards the second, without significantly impacting the dichotomous expression of the asudas, except for some reports in mestizo populations, where reduction has been observed in grades 3 and 4 (pérez et al., 2017). another dental morphological trait that deserves attention in colombian populations is the protostylid. this trait is defined as an indigenous trait with low frequencies in european, african, and asian populations. the high expression of the p-point is particular to american populations (zoubov, 1998). in their study, hernández et al. (2014) concluded that the frequency of the protostylid of the first lower permanent molars allowed the grouping of the categories mentioned, according to the three established world dental complexes. in this way, the processes of mixed origin influenced its expression by decreasing the groove expression, weak or small cusp and free cusp tip in the indigenous groups and increasing the pit expression or p-point in the euro-descendant and afro-descendant mixed populations. however, the protostylid was not, by itself, a morphological feature that discriminated the population groups of southwestern colombia. regarding the cuspid pattern and the deflecting wrinkle, two traits considered to belong to the asian populations, parra et al. (2017) correlated their expression in different contemporary populations. they concluded that, due to the mixed origin of the population of southwestern colombia (south of valle del cauca and north of the department of cauca) from euro-descendant mixed populations, indigenous and afro-descendant ethnic groups, the expressions of both traits showed great variability. this made it possible to differentiate the groups of euro-descendant mixed populations and afro-descendants (with a tendency towards the european populations) from the indigenous groups (with a tendency towards the asian populations). this was represented in the configuration of deciduous lower first molars with significant frequencies of cuspid pattern (y expression) and deflecting wrinkle (grades 2 and 3), permanent lower first molars with relative frequencies of cuspid pattern (y and + expressions) and deflecting wrinkle (grades 1 and 2), and permanent lower second molars with significant frequencies of cuspid pattern (+ and x expressions) and deflecting wrinkle (grades 1 and 2). the classic y groove pattern (dryopithecus pattern) predominates in asian populations, while the x and + configurations considered reductions predominate in african and european populations. therefore, the variability in the configuration of the way the cusps contact each other and the number of cusps tends to conserve the classic pattern and reduce to the other patterns as mixed origin with european and african populations becomes evident. finally, the expression of cusps 6 and 7 has been considered ethnically distinctive. hanihara (1992) identified cusp 6 as being more prevalent in asian populations, while turner (1984) demonstrated high frequencies of this cusp in groups of paleoindians and pre-hispanic amerindians due to its origin. on the other hand, cusp 7 has been observed with greater frequency in afro-descendant populations. in contemporary colombian populations, the expression of both cusps has varied depending on the asian, european, and african ethnic components and the extent of historically mixed populations associated with the geographic distribution of a specific population (rodríguez, 2003). dental complexes since the 1991 political constitution, colombia has identified itself as a multicultural and multiethnic country, acknowledging the presence of five ethnic groups: native americans, afro-colombians (differentiated into negros, raizales and palenqueros according to the 2015 national population and housing census), romani populations (rom or gypsy group that is part of the ethnic and cultural diversity of colombia), and mixed populations without ethnic recognition (called mestizos) dispersed throughout various geographical regions shaped by ethnohistorical processes during the conquest, colony, struggles for independence, formation of the republic, and the current armed conflict. dental morphology studies have provided valuable contributions to the ability to compare past and present populations based on the frequency (expression) and variability (gradation) of dental morphological traits. various statistical methods, such as similarity or dissimilarity matrices, have been employed to determine the proximity or distance between populations. these matrices can be plotted using dendrograms, which show the biological distances between human groups. in the anthropological context, smith's mean measure of divergence (mmd) has been predominantly used, which is based on the degree of dissimilarity between samples. however, in the colombian dental context, the squared euclidean distance has been commonly used to obtain a distance matrix for hierarchical cluster analysis. both statistical methods rely on the frequencies of dental morphological 27 dental anthropology 2023 │ volume 36│ issue 02 traits that can be grouped into clusters to represent the way in which human populations are associated, either by similarity or dissimilarity, regarding their geographic distribution. these studies have made it possible to ethnically classify human beings into complex populations based on dental morphology. due to the complexity of the concept of race, the research group of dental anthropology and forensic dentistry has adjusted the use of the notions of ethnicity and ancestry to avoid biological determinism and incorporate concepts from social anthropology, sociology, and historiography. this approach has enabled the group to focus the research discussion on genotype, phenotype, dental complexes, and geographic distribution. the homogenizing narrative of mixed origin has been challenged, and the notion of interculturality is being explored to integrate the ethnocultural diversity of the entire colombian population. the term "dental complex" or "population dental complex" refers to the way in which past and present human populations can be grouped based on the frequency and variability of dental morphological traits. this allows for grouping populations based on their asian, european, and african origins, as well as the way in which they behave intragroup and intergroup (turner, 1984, 1990; hanihara, 1992; irish, 1997; zoubov, 1998; edgar, 2007). in colombia, the study of dental morphology and its association with the revised dental complexes has been challenging due to the complex ethnohistoric processes that have occurred in the region. rodríguez (2003) proposed that past indigenous populations were characterized by high frequencies of winging, crowding, hypocone reduction, deflecting wrinkle, and the p-point of the protostylid, which placed them closer to the paleoindians derived from the sinodonts. however, for contemporary indigenous populations, the study of dental morphology and its association with the described dental complexes has been complicated due to 500 years of mixed origin resulting from the arrival of western european groups, represented by the spanish conquistadors, and african groups represented by african slaves who populated the american territory in three historical processes recognized as the discovery, conquest, and colony. this process of mixed origin was particularly pronounced in the southwestern region of colombia, especially in the south of the department of valle del cauca and the north of the departamento del cauca. this justifies why the largest number of studies on contemporary populations described as mixed populations, afro-descendants, and indigenous colombians have been conducted in that region by the research group of dental anthropology and forensic odontology at the universidad del valle. the results of these studies concluded that the frequency of morphological traits is a consequence of mixed origin and the dominance of certain phenotypic expressions of morphological traits. thus, mixed populations were characterized by the simplification of dental morphology, with low frequencies of carabelli's trait, which was ambiguously expressed in its fossa forms (asiatic characteristic) and medium-sized cusps (european characteristic) the reduction of the hypocone, which is typical of western european populations, and the high frequency of the protostylid p-point, a trait exclusive to american indian populations (moreno et al., 2004; pérez et al., 2017). contemporary indigenous populations have preserved the asian populations with significant frequencies of winging, crowding, shovel-shaped incisors, the deflecting wrinkle, the protostylid ppoint and the cuspid y groove pattern; however, they have incorporated morphological features of the european populations such as carabelli’s trait (fossa expressions and small cusps) and the cuspid x and + pattern (diaz et al., 2014) and afrodescendant populations have been characterized by presenting high frequencies of medium-sized carabelli trait, cuspid + pattern, x pattern and high frequency of cusp 7, suggesting a notable influence of the european populations (marcovich et al., 2012; rocha et al., 2007; garcía et al., 2015). delgado-burbano (2007) indicated that afrocolombians derive from africans who arrived in the american continent as slaves from west africa, central west africa (sub-saharan africa), southeast africa, and the north, all of them classified in the african-western dental complex. the dental morphological traits that have been most widely used to estimate the ethnic pattern in the colombian anthropological and forensic contexts are the carabelli’s trait, protostylid, cusp 6, and cusp 7, which have high taxonomic value and intragroup discriminating power. the statistical information accumulated from different world populations has allowed grouping the populations through the frequency and variability of these traits, represented in distance matrices and plotted through dendrograms (rodriguez, 2003). the dendrogram generated by pérez et al. (2017), which grouped the largest number of colombian populations studied based on these morphological traits and according to the influence of the three world dental complexes, is included in this article (figure 2). 28 dental anthropology 2023 │ volume 36│ issue 02 the dendrogram shows that mixed groups, afro -descendants, and indigenous people are distributed in clusters according to the dichotomous expression and variability of the four traits included in the analysis. the expressions of carabelli’s trait in fossa (grade 1 to grade 3 asudas), protostylid in grooves and small cusps (grade 2 and 3 asudas), cusp 6 in small cusps (grade 1 and 2 asudas), and the absence of cusp 7, grouped populations with a tendency to the asian dental complex, as in the case of groups of emberá, paeces, nasa, guane, and nukak indigenous groups distributed in specific geographic regions where contact with other groups of mixed groups and afro-descendants has been reduced. in contrast, indigenous groups such as coreguaje, guahibo, waunana, misak, and muruimuinane, who share territory with mixed groups from cali and popayán, as well as afro-descendant groups from puerto tejada, villarica, and guapi, presented a higher frequency of carabelli’s trait in small cusp expression (grade 4 asudas). on the other hand, these same mixed and afrodescendant groups were characterized by cuspid expressions of the carabelli trait and the expression of cusp 7 (grades 2 and 3 asudas), even though they exhibited pit expressions of carabelli’s trait and the p-point of the protostylid associated with the intense process of mixed origin that has historically occurred in the southwest of colombia figure 2. dendrogram showing the biological distance between different colombian populations and colombian populations of mixed groups, native americans, and afro-descendants, based on the frequency and variability of the carabelli trait, protostylid, cusp 6 and cusp 7. *contemporary colombian human populations studied by the research group of dental anthropology and forensic odontology of the universidad del valle. 29 dental anthropology 2023 │ volume 36│ issue 02 with nasa and misak indigenous groups. it is worth noting that the p-point expression can be found in the same tooth as other grades of the protostylid; however, in contemporary populations of southwestern colombia (mixed groups, afrodescendant, and indigenous groups), the prevalence of the cuspid expression of this trait is practically absent, according to the dichotomous expression defined by asudas, while the prevalence of the p-point is between 80% and 100% (hernández et al., 2014). interest in the forensic context during the process of forensic identification and medical-legal documentation, whether dealing with living or deceased individuals, it is crucial to establish their identity. the search for identity is conducted through the general biographical reconstruction, also known as the biological profile. this includes the estimation of age, sex, ethnic pattern, and stature through the application of validated bioanthropological methods (rodriguez et al., 1995). teeth provide significant information for estimating age (chronology of dental development and eruption, as well as dental wear), sex (dental measurements), and population pattern (dental morphology), and in many cases, are the only element capable of providing biological and cultural information on an individual or human population (rodríguez, 2003; rodríguez-flórez, 2003, 2005). most population studies on dental morphological traits have demonstrated their great value in classifying human groups according to their ethnic origin and geographic distribution, and the absence of sexual dimorphism and bilateral asymmetry in the expression of dental morphological traits. additionally, particular expressions of tubercular features, such as paramolar cusps (carabelli’s trait, parastyle, and protostylid), can individualize a human being (rodriguez, 2003, 2004, 2011). in colombia, the instituto nacional de medicina legal y ciencias forenses reported in 1993 that 72% of all cases in which bone and dental remains were analyzed with bioanthropological techniques and methods corresponded to mixed origin populations with caucasoid characteristics, while 28%, 7%, and 1% corresponded to mixed origin populations with asian, indigenous, and afro-descendant characteristics, respectively (rodriguez, 2004). despite ongoing controversy over the use of dental morphological traits and their limitations, their observation and recording can be considered as an attempt to test their validity as a method of ancestry estimation in a forensic context (edgar, 2005; 2013). therefore, it is necessary for research areas to keep constant work and to carry out studies on statistical prediction models to test whether dental fmorphological traits are valid as a method of ancestry estimation in a forensic context, or if they can be used as a complementary method to others (lópez-lázaro et al., 2016). based on the information presented in this article, studies on morphological characterization carried out in contemporary populations of southwestern colombia have shown that the frequency and variability of dental morphological traits differ among mixed populations, afro-colombian populations, and contemporary indigenous populations (moreno-gómez, 2019): mixed populations are characterized by low expressions of shovel-shaped incisors (grades 2 and 3 asudas), fossa and cuspid expressions of carabelli's trait (grades 3 and 4 asudas), hypocone reduction (grades 2 and 3 asudas), absence of deflecting wrinkle, variations of the cuspid pattern between y and + with five cusps; absence of protostylid combined with mean p-point expressions, and absence of cusps 6 and 7. afro-colombian populations are characterized by absence of shovel-shaped incisors, cuspid expressions of carabelli’s trait (grades 4 and 5 asudas), hypocone reduction (grades 2 and 3 asudas), absence of deflecting wrinkle, cuspid x or + pattern with five or six cusps, absence of protostylid combined with middle expressions of p-point, and relative expressions of cusp 7 (grades 2 and 3 asudas). contemporary indigenous populations are characterized by high frequencies of shovel-shaped incisors (grades 3 to 6 asudas), reduced carabelli’s trait (grades 2 and 3 asudas), absence of hypocone reduction, deflecting wrinkle (grade 3 asudas), cuspid y groove pattern with five and six cusps, groove expressions and small protostylid cusps (grades 2 and 3 asudas) combined with p-point, and relative expressions of cusp 6 (grades 2 and 3 asudas). however, according to the territory occupied by the human groups and the historical processes of mixed origin, the behavior (frequency and variability) of some of the traits may change. conclusions this literature review has enabled the continuous work of the dental anthropology and forensic dentistry research group at the school of dentis30 dental anthropology 2023 │ volume 36│ issue 02 try of the universidad del valle (cali, colombia) to be followed up. for nearly 20 years, this group has characterized the dental morphology of southwestern colombia through the study of the frequency and variability of dental morphological traits in different populations of mixed groups, afrodescendants, and native americans. however, it is necessary to expand the research on other topics of dental anthropology that have been barely addressed by the dental anthropology and forensic dentistry research group, such as the study of dental measurements, dental eruption patterns, and dental pathologies applied to anthropological and forensic contexts. the strategies employed by the dental anthropology and forensic dentistry research group, including formative research and the formation of cooperative research networks, have contributed to the publication and dissemination of the results of studies on dental morphology, mainly in the colombian dental clinical context. the thematic direction of the studies and the journals in which the articles were published demonstrated the impact on the knowledge that dentists have about dental morphology from an anthropological point of view, and how this knowledge can be applied to their clinical interest as etiological factors associated with the accumulation of bacterial plaque and the subsequent development of caries and periodontal disease. however, the publication of research in international anthropological contexts is limited by the lack of publications in english and resistance from some specialized journals to research in contemporary colombian populations. nevertheless, it is important to understand that, given the current conditions for research and publication in dental anthropology, researchers from universities in the united states, great britain, and australia have been able to create a broader vision of the study of dental morphology by comparing and contrasting anthropological knowledge from latin american countries, such as colombia, based on information published in english and highimpact specialized journals. from an anthropological perspective, one of the most significant accomplishments of the research group has been the systematic study of contemporary colombian populations of european, native american, and african origin, historically settled in southwestern colombia. this has enabled the construction of a population dendrogram based on the frequency and variability of four non-metric dental traits (carabelli’s trait, protostylid, cusp 6, and cusp 7), which have been observed, registered, and analyzed using the asudas methodology. these findings are comparable to other population studies that have used this methodology worldwide. additionally, it has been identified that the expression of dental morphological traits is bilaterally symmetrical and does not present sexual dimorphism. considering that forensic dental identification processes rely on comparative and reconstructive methods, it is crucial to urge clinical odontologists to include in clinical records the description of the presence and variation of morphological characteristics with marked expressions in the four classes of teeth and in both dentitions. this would allow dental experts and forensic anthropologists to use dental morphology in estimating the ethnic pattern during the biographical reconstruction of an individual or their human remains. hence, dental morphological features can become reliable markers for comparative use in antemortem-postmortem comparisons when carrying out the biological profile. in conclusion, the efforts of the dental anthropology and forensic dentistry research group are currently focused on finding ways to make the international dental anthropological and dentistry community aware of the research on colombian dental anthropology. the researchers, comprising anthropologists and odontologists, have appropriated various theories and methods to create their own discourse on the behavior of dental morphological traits. this article precisely presents an account of this “discurso propio del otro (nosotros)” and is presented in tension with the anxiety produced by encountering the “discurso universal del hegemónico (ustedes)” with whom we share the ambition of generating applicable knowledge in the anthropological, dentistry and forensic contexts. the aim is to make the knowledge generated during these 20 years of work visible and to believe that it is possible to think outside the hegemonic discourses. acknowledgements the authors express their gratitude to dentist maría del mar díaz posso for her contribution to the tabulation of the scientific papers considered in this publication. references acosta, d., porras, a., & moreno, f. 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(2010). antropología dental y periodoncia: relación entre los rasgos morfológicos dentales y la enfermedad periodontal. acta odontológica venezolana, 48(3). turner, c.g. (1984). advances in the dental search for native american origins. acta anthropogen, 8 (1-2), 23-78. turner, c.g. (1990). major features of sundadonty and sinodonty, including suggestions about east asian microevolution, population history, and late pleistocene relationships with australian aboriginals. american journal of physical anthropology, 82, 295-317. van reenen, f., reid, c., & butler, p. (1998). morphological studies on human premolar crowns. in mayhall, j.t., heikkinen, t. (editors). dental morphology. proceedings of the 11th international symposium on dental morphology, oulu, finlandia, 192-205. zoubov, a.a. (1998). la antropología dental y la práctica forense. maguaré, 13, 243-252. zúñiga, s., moreno, s., & moreno, f. (2016). caracterización morfológica de los segundos molares temporales y los primeros molares permanentes de tres grupos étnicos de la región del chocó (colombia). revista nacional de odontología, 12(22), 43-59. 19 dental anthropology 2014 │ volume 28 │ issue 03 contextualizing buccal dental microwear variations during the byzantine period in jordan mohammad alrousan, ali khwaileh, and abdulla al-shorman department of anthropology, yarmouk university, irbid, jordan keywords: diet, dental wear, hunter-gatherers, food processing, natufian introduction the byzantine period (324–638 ce) in the levant and particularly in jordan has received influential thoughts by historians on both sociopolitical and economic levels (jones, 1964). the archaeological studies refuted the historians’ thoughts (kingsley, 2001) but unfortunately few dealt with the subject in a broader economic view (rose et al., 2007). however, local economic variations must have been existed, triggered by the varied subsistence economies. one of the best models in this regard is the byzantine site of natfieh, where agriculture and animal husbandry were the sources of food (al-bashaireh et al., 2010). social stratification in terms of populace and elites was common during this period, which exerted a wider gap in wealth accumulation between urban and rural settlements, or even on a settlement level (grossman, 1974; garnsey and saller, 1987). therefore, selfsufficient economies that relied on land as the main source of food production and improvisation were presumably site-specific and might not be applied at other contemporaneous byzantine settlements in jordan. the function of a settlement might have possessed another check on economic success, such as, the late roman/early byzantine military garrison discovered near queen alia international airport (ibrahim and gordon, 1987), these sites did not excersiced a complex subsistence economy but mostly relied on aid from the central goverment. another unique byzantine settlement, in this sense, is khirbit yajuz in the middle of jordan. the site was proved to be a substantial producer of textile in the region (khalil, 1998; al-shorman, 2003; al-shorman and khalil, 2006) but it is not known yet if other subsistence economies were additionally practiced. during the same period, the people of the byzantine site of sa’ad -at the edge of the arid zone -in northern jordan subsisted on agriculture, produced huge amounts of wine for export purposes, and believed to be self-sufficient (rose et al., 1997). the two different economic models in khirbit yajuz and sa’ad (fig. 1) would have created two different dietary forms for local consumption that could be reconstructed. accordingly, this study investigates the type of diet among the people of these sites using buccal dental microwear depicted by scanning electron microscopy of teeth. abstract this study scanned 14 buccal surfaces of teeth casts microscopically from the byzantine sites of yajuz and sa'ad in jordan, and 7 samples from the natufian site of el wad in palestine for the purpose of studying buccal microwear. the results show no differences in the pattern of dental microwear between the two byzantine sites, while a difference was existed when these sites compared to el wad. the results indicate that subsistence economy did not trigger buccal microwear but cultural development. although the economies during the byzantine period were diversified, technological adaptation diffused into region, which eased food accession and procession. correspondence to: mohammad alrousan, department of anthropology, yarmouk university, irbid , jordan. fig. 1. the archaeological sites of khirbit yajuz and sa’ad, jordan. 20 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 the buccal dental microwear analysis is one of the direct methods in reconstructing diet through examining the microscopic surfaces of teeth (grine et al., 2002). contrary to occlusal microwear, buccal microwear provides insights on diet over a longer time and is not affected by tooth-to-tooth contact (pérez-pérez et al. 1994; pérezpérez, 2004; romero et al., 2012). for this reason, buccal dental microwear has become very common and widely accepted as a tool for reconstructing primates’ diet and ecology (galbany et al., 2003; 2004; 2005; 2009), and dietary adaptation and behavior of extinct human populations (romero et al., 2004; martinez et al., 2004; romero, 2005; polo-carda et al., 2007; romero and de juan, 2007; alrousan and pérez-pérez, 2008; 2012 estaberanz et al., 2008; 2009; alrousan et al., 2009). the recent studies have focused on the experimental research to improve the quantification of buccal microwear analysis using precise digital techniques (martinez and pérez-pérez, 2004; galbany et al., 2005). the abrasive particles in the diet induce microwear on the buccal surfaces of teeth. these particles are either intrinsic to diet, such as, phytoliths of plant tissues, which have hardness that exceeds dental enamel (piperno, 1988; lauleza and pérez-pérez, 1994) or extrinsic when dust, ash, or sand contaminates food during processing (mahoney, 2006; alrousan and pérez-pérez, 2008; 2012; alrousan, 2011). despite the source of these particles, they eventually cause both pits and striations on occlusal surfaces of teeth (teaford and oyen, 1989; schmidt, 2001; mahoney, 2006; ungar et al., 2008; alrousan, 2011) but only striations on the vestibular or buccal surfaces (puech and albertini, pérez-pérez 1983; pérez-pérez; 1994; 1999; 2003; alrousan and pérez-pérez, 2008; 2012). meat, for example, is correlated with a large number and longer vertical striations on the buccal surfaces of the teeth, whereas plant items tend to cause higher densities of longer horizontal striations (puech, 1976; 1979; puech and albertini, 1981; 1984; puech and pant, 1980; puech et al., 1980; 1983; 1986; pérez-pérez et la., 1994; lalueza et al., 1996; alrousan and pérez-pérez, 2012). accordingly, the buccal microwear pattern is a reliable, nondestructive, and accurate method for dietary reconstruction because it can reflect dietary changes over the long term rather than providing evidence on the “last supper” (pérez-pérez et al., 1994; alrousan, 2009; romero et al., 2012). the presence of microwear features on the occlusal surface depends on many factors; the mechanics of chewing, mastication forces, the position of analyzed wear facet, and the section of analyzed wear facet (kay and hiiemae, 1974; gordon and walker, 1983; pérez-pérez, 2004; mahoney, 2006). on the other hand, buccal surfaces are not affected by tooth-to-tooth contact during chewing cycle, with minimal effect by the forces of mastication (puech and pant, 1980; lalueza and pérez-pérez, 1993; pérez-pérez et al., 1994; pérez-pérez, 2004). the presence of extensive tooth wear or the use of teeth as a tool makes the analysis of occlusal microwear impossible. for these reasons, bioarchaeoligiests tend to extract dietary information from the enamel surface using buccal dental microwear technique. materials and methods for the purpose of this study, buccal dental microwear patterns were collected from 14 individuals; 7 from the byzantine site of khirbit yajuz in the middle of jordan and 7 from the byzantine site of sa’ad in northeastern jordan. a single post-canine tooth was chosen to represent each individual, all individuals are right fully developed third molars (alrousan and pérez-pérez, 2008; pérezpérez et al., 2003). the samples have well-preserved enamel surfaces without dental pathologies. according to microwear standards, post-mortem changes, taphonomic changes, and unpreserved enamel surfaces were determined after teaford (1988), martinez and pérez-pérez (2004) and pérez-pérez et al. (2003). the surfaces of dental enamel were gently cleaned with pure acetone and then rinsed with 70% ethanol using cotton swabs. molds of the original teeth were obtained using polyvinyl-siloxane president microsystems™ (coltene regular body) (galbany et al. 2006; ungar et al. 2006). positive casts of tooth molds were obtained using epoxy resin (epo-tek 301, by qda) with a two-stage centrifugation procedure to prevent the formation of air bubbles. before examining the casts under sem (scanning electron microscope), the samples were mounted on aluminum stubs with carbon gum. the casts were then coated with a 400 å gold layer. the sem observation settings were 15 kv with 0º tilt angle of the secondary electrons. the micrographs were obtained at 100x magnification on the medial aspect of the buccal surface of the cast at a distance from the occlusal rim of the cusps and the cementenamel junction. the images were then cropped to cover an area of 0.56 mm2, where the measure of the side border of each square micrograph was 748.33 µm (fig. 2) (pérezpérez et al. 2003; alrousan and pérez-pérez 2008; 2012). fig. 2. micrograph of buccal microwear 21 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 each micrograph was processed using adobe photoshop by applying a “high pass” (50 pixels) filter and “automatic” level enhancement. in order to quantify buccal dental microwear pattern (striation length and density), sigma scan pro 5 (spss) package was used. the slope and the length of striations in each micrograph were digitally measured. the orientations of the striations were measured according to lalueza et al. (1996) and pérezpérez et al. (1994; 2003). the orientation was measured from 0º to180º and classified as follows (fig. 3): 1. vertical (v): angle ≥ 67.5º and ≤ 112.5º. 2. mesio-occlusal to disto-cervical (md): from 112.5º to 157.5º for the upper left and the lower right teeth. 3. disto-occlusal to mesio-cervical (dm): from 22.5º to 67.5º for the upper right tooth and lower left. 4. horizontal (h): angle ≥ 0º and ≤ 22.2º, and angle ≥ 157.5º and ≤ 180º. for all orientation categories (h, v, md, dm),the total number of striations (t), the density (n), average length (x) and standard deviation of the length (s) of the striations were computed and, thus, a total of 15 microwear variables were derived for each sample (pérez-pérez et al. 1994). a second stage comparison was performed: the first stage is between the two sites; the normality of the frequency distributions of the 15 variables was tested with the kolmogorov-smirnov test for goodness of fit. then, a one-factor anova test was used to compare the 15 variables in the two sites. the second stage of comparison compared the microwear pattern of the byzantine teeth with the natufian teeth from el wad after alrousan and pérezpérez (2012). el wad is a hunter-gatherer site located in palestine, and dated to 12,950 10,680 years bp based on relative and 14c dating (garrod, 1931; weinstein-evron 1991). this comparison is aimed to understand the cultural development regarding food acquisition and processing from hunting and gathering to farming. results the means and standard deviations of the above variables are presented in table 1. the results of statistical analysis are presented in table 2. first stage of comparison results; kolmogorov-smirnov normality tests shows that none of the 15 variables differed significantly from normality for the two sites considered. therefore, parametric statistical tests could be applied to the raw data. no significant differences were discovered between the two sites, sa’ad and yajuz, considering the 15 variables of buccal dental microwear (fig. 4). the second stage of comparison indicates that there are significant differences between the natufian people and the byzantain people at least in ten variables; the length and the standard deviation of horizontal striations, vertical striations, mesodistal striations, distomesial striations, and total striations. the characteristic feature of the buccal dental microwear of the natufian samples is the longer striations in a comparing with that of the byzantine samples (fig. 5). fig. 3. orientations of striation (pérez-pérez et al., 1994) fig. 4. total number of striation of the byzantain sites sa'ad and yajuz. figure 5: length of all striations of the two periods 22 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 site sa’ad no.=8 yajuz ( no.=7) el wad (no.=7) byz (no.=15) mean sd. mean sd. mean sd. mean sd. nh 26.875 10.629 31.571 14.604 35.286 14.930 29.067 12.400 xh 19.779 3.090 20.447 11,009 83.043 40.215 20.091 7.539 sh 10636 2.990 10.394 7.374 59.094 46.071 10.523 5.271 nv 21125 14.759 26.000 8.869 30.143 19.651 23.400 12.205 xv 19.356 4.142 27.006 16.135 79.091 22.976 22.927 11.651 sv 11.657 4.033 18.069 10.914 66.237 23.140 14.649 8.375 nmd 48.125 18.849 55.286 24.088 66.571 39.136 51.467 20.976 xmd 17.394 2.433 22.342 13.331 60.633 13.067 19.703 9.255 smd 11.309 5.913 14.170 10.674 35.056 10.597 12.644 8.276 ndm 44.750 22.487 35.857 10,946 44.000 14.674 40.600 18.035 xdm 17.065 1.896 18.832 7.539 61.189 17.519 17.890 5.195 sdm 9.113 3.888 8.660 4.714 41.134 15.621 8.902 4.140 nt 140.875 48287 148.714 38.156 176.000 63.765 144.533 42.499 xt 18.315 1.685 22.267 11.256 70.652 21.255 20.159 7.739 st 11.515 2.841 14.156 8.489 55.063 24.310 12.747 6.065 table 1: descriptive statistics. el wad results after alrousan and pérez-pérez (2012). sum of squares degree of freedoom mean of squares f probability xh 18914.104 1 18914.104 36.029 .000 sh 11259.504 1 11259.504 17.158 .001 xv 15055.583 1 15055.583 59.417 .000 sv 12701.519 1 12701.519 60.560 .000 xmd 7995.701 1 7995.701 71.912 .000 smd 2397.317 1 2397.317 29.366 .000 xdm 8948.033 1 8948.033 80.640 .000 sdm 4958.516 1 4958.516 58.196 .000 xt 12168.150 1 12168.150 68.573 .000 st 8546.363 1 8546.363 42.093 .000 table 2: anova results 23 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 discussion diet is one of the most important aspects used to understand the paleobiology, evolution, and culture of extinct human populations. in order to reconstruct diet, bioarchaeologists use teeth because of they are the most preserved human skeletal remains, where they are commonly found in ancient burials. the results of buccal dental microwear of this study are highly correlated with the archaeological data and records. the main sources of inter population variation in buccal dental microwear are the number and the length of striations that eventually depended on ecological factors including food availability and resources. for example, buccal microwear patterns from pliocene hominids, in comparison with modern hunter-gatherers with relatively known diet, have showed higher density of striations in corresponding to higher abrasiveness of the diet (pérez-pérez et al., 1994; 2003). the patterns of buccal microwear from neolithic and natufian teeth in the ancient near east showed that the longer striations in the neolithic teeth is due to food processing technique and introduction of more cereals and plants in diet (alrousan, 2009). the index of nh/nv is highly an indicator of the type of consumed diet; hunter -gatherers (meat dependant) and pastoralists tend to have a lower value of this index (lauleza et al., 1996; alrousan and pérez-pérez, 2012). since there are no significant variations between sa’ad and yajuz, this study suggests that the diet in both sites is similar in relation to resource or even processing although the two sites practiced different subsistence economies. sa’ad people depended on agriculture and animal husbandry, while yajuz people practiced textual manufacturing. the previous study of occlusal dental microwear of the same samples of yajuz (alshorman and khalil, 2006) did not extract any information regarding diet and/or dietary adaptation, where occlusal dental microwear pattern was masked by using teeth as tools. the length of striations here is positively correlated with the abrasiveness of diet, more abrasive diet tend to leave longer striations on the buccal surface due to the exerted heavy masticatory forces (puech, 1978; 1982; pérez-pérez et al., 1994; alrousan and pérez-pérez, 2008). therefore, the people of el wad probably consumed a harder diet compared to the byzantine population. the difference between the natufian and the byzantine periods is probably due to the differences in food intake and food processing (cultural development) rather than environmental conditions. the natufian people of el wad were hunter-gatherers; depending more on gathering than hunting (alrousan and perezpérez-pérez, 2012). the gross wear that they had resembled that of pre pottery neolithic people (smith, 1970) as triggered by the presence of grinding tools (henry, 1989; bar yosef, 1998). the large component of plant food created more abrasive materials that needed more masticatory forces and thus caused longer striations. food processing is another factor that affects microwear pattern (teaford and lytle, 1996; ungar and spencer, 1999; alrousan and pérez-pérez, 2008), where after the introduction of pottery in the neolithic period, cooking was facilitated and the texture became softer, which required less maticatory forces. conclusion despite the variation in subsistence economy in rural byzantine settlements, the inhabitants consumed diet that was probably similar in texture, which stresses on the diffusion of cultural development throughout the region. throughout the history of the region, it seems that the technological innovation in cooking utensils reduced the abrasiveness on the enamel surfaces of teeth. the variation in the local economies in rural areas during the byzantine period have imposed little if any restrictions on technological adaptation but does not negate the access to better quality and quantity of food items by the elites. acknowledgements microscopic images were prepared at department of geology/yarmouk university. literature cited al-bashaireh k, al-shorman a, rose j, jull a, hodgins g. 2010. paleodiet reconstruction of the human remains from the archaeological site of natfieh, northern jor dan. radiocarbon 52: 645–652. al-shorman a. 2003. a byzantine tomb from khirbit yaj uz, jordan. j paleopathol 15: 177-185. al-shorman a, khalil l. 2006. the evidenc of weaving at khirbit yajuz in jordan using dental microwear. ijda 8: 1-9. alrousan m. 2009. the mesolithic-neolithic transition in the near east: biological implications of the shift in subsistence strategies through the analysis 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hominoideos: ¿una cuestión de especie o de en torno ecológico? rev esp antropol biol 23: 77-83. galbany j, martínez lm, pérez-pérez a. 2004. tooth repli cation tecniques, sem imaging and microwear analysis in primates: methodological obstacles. anthropologie 42:5-12. galbany j, pérez‐pérez a. 2004. buccal enamel microwear variability in cercopithecoidea primates as a reflection of dietary habits in forested and open savanna environ ments. anthropologie. 42: 13‐19. galbany j, estebaranz f, martínez lm, romero a, de juan j, turbón d, pérez-pérez a. 2006. comparative analysis of dental enamel polyvinylsiloxane impression and polyurethane casting methods for sem research. microsc res tec 69:246-252. garnsey p, saller r. 1987. the roman empire: economy, society and culture. berkeley: university of california press. gordon kd, walker ac. 1983. playing 'possum: a micro wear experiment. am j phys anthropol 60: 109-112. grine fe, ungar ps, teaford mf. 2002. error rates in den tal microwear 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2006. dental microwear from natufian hunter-gatherers and early neolithic farmers: compari sons within and between samples. am j phys anthro pol 130: 308-319. mahoney p. 2007. human dental microwear from ohalo ii (22500-23500 cal bp), southern levant. am j phys an thropol 132: 489–500. pérez-pérez a. 2004. why buccal microwear? anthropolo gie 42: 1-2. pérez-pérez a, lalueza c, turbón d. 1994. intraindividual and intragroup variability of buccal tooth striation pat tern. am j phys anthropol 94: 175-187. pérez-pérez a, bermúdez de castro jm, arsuaga jl. 1999. nonocclusal dental microwear analysis of 300,000 year old homo heilderbergensis teeth from sima de los huesos (sierra de atapuerca, spain): implications of intrapopulation variability for dietary analysis of homi nid fossil remains. am j phys anthropol 108: 433-457. pérez-pérez a, espurz v, bermúdez de castro jm, de lumley ma, turbón d. 2003. non-occlusal dental mi crowear variability in a sample of middle and upper pleistocene human populations from europe and the near east. j hum evol 44: 497-513. piperno dr. 1988. phytolith analysis: an archaeological and geological perspective. san diego: academic press. polo m, romero a, casabó j, de juan, j. 2007. the bronze age burials from cova dels blaus (vall d′uixó, castel ló, spain): an approach to palaeodietary reconstruction through dental pathology, occlusal wear and buccal microwear patterns. homo 58: 297-307. puech pf. 1976. recherche sur le mode d’alimentation des hommes du paléolithique par l’étude microscopique des couronnes dentaires. in: de lumley h, editor. la préhistoire française i. centre national de la recher che scientifique. p 708-709. puech pf. 1979. the diet of early man: evidence from abrasion of teeth and tools. curr anthropol 20: 590-592. puech pf, albertini h. 1984. dental microwear and mech anisms in early hominids from laetoli and hadar. am j phys anthropol 65: 87-91. puech pf, albertini h, mills n. 1980. dental destruction in broken-hill man. j hum evol 9: 33-39. puech pf, albertini h, serratrice c. 1983. tooth micro25 contextualizing buccal dental macrowear dental anthropology 2014 │ volume 28 │ issue 03 -wear and dietary patterns in early hominids from lae toli, hadar, and olduvai. j hum evol 12: 721-729. puech pf, cianfarani f, albertini h. 1986. dental micro wear features as an indicator for plant food in early hominids: a preliminary study of enamel. hum evol 1: 507-515. puech pf, pant r. 1980. un modele d'etude de l'alimenta tion des hommes fossiles. bull mém soc anthropol paris 7:61-64. romero a, martínez-ruiz n, de juan j. 2004. non occlusal dental microwear in a bronze-age human sam ple from east spain. anthropologie 42:65-70. romero a, de juan j. 2007. intraand inter-population human buccal tooth surface microwear analysis: infer ences about diet and formation processes. anthropol gie 45: 61-70. romero a, galbany j, de juan j, pérez-pérez a. 2012. brief communication: shortand long-term in vivo human buccal dental-microwear turnover. am j phys anthropol 148: 467-472. rose jc, el-najjar my, burke d. 2007. trade and the ac quisition of wealth in rural late antique north jordan. in: al-khraysheh f, editor. studies in the history and archaeology of jordan ix. amman: department of an tiquities. p 61-70. rose jc, el-najjar my, turshan n, sari s. 1997. sa’ad: preliminary report. newsletter of the institute of an thropology and archaeology 2: schmidt c. 2001. dental microwear evidence for a dietary shift between two nonmaize-reliant prehistoric popula tions from indiana. am j phys anthropol 114: 139-145. teaford mf. 1988. scanning electron microscope diagno sis of wear patterns and artifacts on fossil teeth. scan ning microsc 2: 1167-1175. ungar ps, grine fe, teaford mf. 2008. dental microwear indicates that paranthropus boisei was not a hard object feeder. plos one 3: 1-6. sherwood and reddy 2011.3 16 van valen (1962) grouped deviations from perfect symmetry in an organism into three categories: (1) directional asymmetry; (2) antisymmetry; and (3) fluctuating asymmetry (an asymmetry involving a paired structure that is usually symmetrical). fluctuating asymmetry may be either quantitative or qualitative (lundström 1961). bilateral asymmetry in root number is quantitative variation and root morphology asymmetry is qualitative variation. fluctuating asymmetry has been associated with congenital abnormalities, genetic syndromes, and elevated levels of inbreeding, and it is also thought to be a general indicator of stress caused by nutritional and/ or disease during development (scott and turner 2000). teeth in corresponding quadrants of the upper and lower jaws are normally symmetrical structures that exhibit mirror imagery. asymmetry does occur, at varying levels, for all crown and root traits, including overall tooth size, cuspal dimensions, hypodontia and hyperdontia. numerous studies have explored both the quantitative and qualitative nature of fluctuating asymmetry in crowns of the teeth (both size and morphological variation) among various populations (lundström 1963; garn et al. 1966; dibennardo and bailit 1978; baume 1979; townsend 1981; noss et al. 1983; kieser et al. 1986; kieser and groeneveld 1988; scott and turner 2000; wetherell et al. 2004). but, with regard to fluctuating asymmetry for root number and morphology, studies are very limited (sabala et al. 1994). the present cases highlight the importance of the clinician and researcher to understand this phenotypic variation. a total of 21 cases are described exhibiting macroscopic fluctuating asymmetry in root number and morphology of permanent premolars and molars. this report describes four mandibular second premolars with extra roots, seven mandibular first molars with extra roots, four mandibular second molars with c-shaped roots, two mandibular second molars with extra roots, three mandibular third molars with extra roots, and one maxillary second molar with extra root configurations. the subjects reported here were treated in the department of conservative dentistry and endodontics in the csi college of dental sciences, madurai, india, or a private referral clinic in madurai, india, during the period between year june 2007 and december 2010 and were from the local indigenous tamil speaking population. the bilateral eccentric periapical radiographs of patients who visited for treatment of either pain or caries were obtained (30-degree mesial angulation using a protractor). all the periapical radiographs were taken using an x-mind® ac x-ray generator (satelec acteon group, gustave eiffel, france) operated at 70 kvp and 8 fluctuating asymmetry in root number and morphology of permanent premolars and molars—case reports i. anand sherwood1 and p. govinda reddy2 1department of conservative dentistry and endodontics, csi college of dental sciences, madurai – 02, tamil nadu, india 2department of anthropology, university of madras, chennai, india correspondence to: i. anand sherwood , “anand dental clinic”, number 1, meenakshi towers, p. t. rajan road, bibikulam, madurai – 02, tamil nadu, india e-mail: anand.sherwood@gmail.com abstract aim of this article is to report cases with fluctuating asymmetry in root morphology and root number in permanent premolars and molars and to survey the literature about reporting for fluctuating asymmetry in roots of teeth. fluctuating asymmetry is a left-right asymmetry of a paired structure that is usually symmetrical. teeth in corresponding quadrants of the upper and lower jaws are normally symmetrical structures that exhibit mirror imagery. fluctuating asymmetry does occur at varying levels for all root traits. fluctuating asymmetry for root morphology and number has been poorly studied. in this article, 21 cases with fluctuating asymmetry in root number and morphology of permanent premolars and molars are reported. key points are: (1) fluctuating asymmetry seems to be occurring in tamil speaking population of madurai south india more frequently than reported for caucasian populations. (2) more detailed study of variation in root morphology with greater emphasis on fluctuating asymmetry for root morphology is warranted. 3) fluctuating asymmetry is of importance to clinical dentists, dental morphologists, and dental anthropologists. dental anthropology 2011;24(1):16-24. 17root asymmetry fig. 1. (left) mandibular left second premolar. (center) mandibular right second premolar of the same case (diagnostic radiograph). (right) postoperative mandibular right second premolar showing two roots. case is a 45 year old female. fig. 2. (left) mandibular left second premolar. (right) postoperative mandibular right second premolar showing two roots. case is a 35 year od male. fig. 3. panoramic radiograph showing mandibular left second premolar with two roots and mandibular right second premolar with only one root. case is a 21 year old female. fig. 4. panoramic radiograph showing mandibular left second premolar with two roots and mandibular right second premolar with only one root. case is a 16 year old female. ma. size 2 periapical kodak dental films (eastman kodak co., rochester, ny) were used. periapical radiographs were taken using paralleling cone technique and films were held using film holders. panoramic radiographs used in this report were taken using planmeca x-ray unit (proline ec, helsinki, finland). films were developed using manual x-ray developer and fixer (eastman kodak co., rochester, ny) by the time and temperature method. the radiographs were placed on a viewing box, and the light surrounding the radiograph was blocked. each radiograph was independently studied by two independent reviewers by using magnifying lens (3x). disagreement in the interpretation of images was discussed with two endodontists, and a consensus was reached (tu et al. 2007, schafer et al. 2009). the criteria for the indication of an extra root were justified by crossing the translucent lines, defining the pulp space and the periodontal ligaments (walker and quackenbush 1985). mandibular second premolars report 1 a 45 year old female reported to the department with the complaint of pain in the mandibular right first and second premolars, a diagnosis of irreversible pulpitis was made. on examination, the periapical radiograph (fig. 1b) of the mandibular right second premolar showed that the tooth had two separate roots in mesiodistal orientation. this was confirmed during root canal treatment (fig. 1c). a contralateral radiograph (fig. 1a) was taken for the mandibular left second premolar, and it had only one root. report 2 a 35 year old male was referred with the complaint of pain in both right and left mandibular second premolars. a diagnosis of irreversible pulpitis due to carious pulp exposure was made. on examination of radiographs (fig. 2b) the mandibular right second premolar had two separate roots in mesiodistal orientation while the mandibular left second premolar (fig. 2a) had only one root. report 3 a 21 year old female reported with a complaint of pain in the mandibular right third molar region, and a panoramic radiograph was advised. on examination, pain was diagnosed as being due to a mandibular right third molar impaction. it was noted on the panoramic radiograph (fig. 3) that the mandibular left second premolar had two separate roots in mesiodistal orientation, whereas the mandibular right second premolar had only one root. 18 fig. 6. (left) preoperative diagnostic radiograph of a mandibular right first molar showing the presence of a radix entomolaris. (center) post-obturation radiograph confirming the presence of a radix entomolaris on the mandibular right first molar. (right) radiograph of the mandibular left first molar showing the absence of anyextra root. case is a 15 year old male. fig. 7. (left) preoperative diagnostic radiograph showing the presence of a radix entomolaris on the mandibular left first molar. (center) post-obturation radiograph confirming the presence of a radix entomolaris on the mandibular left first molar. (right) radiograph of the mandibular right first molar showing no extra root. case is a 27 year old female. fig. 8. (left) radiograph showing the presence of a radix entomolaris on the mandibular right first molar. (right) radiograph of the mandibular left first molar showing no extra root. case is a 36 year old male. report 4 a 16 year old female was referred by an orthodontist for restoration and management of dental caries in the mandibular right and left first molars. it was noted that the patient had dentinal occlusal surface caries on the mandibular right and left second first molars, and they were managed with class i composite restorations. on examination of a panoramic radiograph (fig. 4) taken for orthodontic purposes, it was noted that the mandibular left second premolar had two separate roots in mesiodistal orientation, whereas the mandibular right second premolar had only one root. all the mandibular second premolars with extra root configuration in this report had vertucci type iv canal configuration (vertucci 1984). mandibular first molars report 5 a 34 year old male reported with a complaint of pain in the mandibular left first molar. it was noted on the radiograph that a class i amalgam restoration was impinging on the mesial pulp horn; a diagnosis of irreversible pulpititis was made and root canal treatment was undertaken. the periapical radiograph (fig. 5a) showed that the mandibular left first molar had an extra root, a radix paramolaris (carlsen and alexandersen 1991). the contralateral periapical radiograph (fig. 5c) showed that that tooth had only two roots. presence of a radix paramolaris was confirmed during root canal treatment of the mandibular left first molar (fig. 5b). report 6 a 15 year old male was referred with pain in the mandibular right first molar and was diagnosed with irreversible pulpitis and root canal treatment was undertaken. the periapical radiograph of the mandibular right first molar (fig. 6a) showed that the tooth had an extra root, a radix entomolaris (carlsen and alexandersen 1990). but the contralateral tooth (fig. 6c) had only two roots. presence of a radix entomolaris in mandibular right first molar was confirmed during the root canal treatment (fig. 6b). report 7 a 27 year old female reported to the department with the chief compliant of pain in the mandibular left first molar. she was diagnosed with irreversible pulpitis and root canal treatment was undertaken. the periapical radiograph (fig. 7a) disclosed that the mandibular left first molar had an extra root, a radix entomolaris. the contralateral periapical radiograph (fig. 7c) showed that that tooth had only two roots. presence of a radix entomolaris on the mandibular left first molar was confirmed during root canal treatment (fig. 7b). fig. 5. (left) preoperative diagnostic radiograph showing presence of radix paramolaris on mandibular left first molar. (center) post-obturation radiograph confirming the presence of a radix paramolaris on mandibular left first molar. (right) radiograph of mandibular right first molar shows no presence of an extra root. case is a 34 year old male. i.a. sherwood and p.g. reddy 19root asymmetry fig. 9. radiograph showing the presence of a radix entomolaris on the mandibular right first molar, but not on the mandibular left first molar. case is a 19 year old male. fig. 10. (left) periapical radiograph of a mandibular left first molar showing no extra root. (right) extracted mandibular right first molar having an extra root radix entomolaris. case is a 32 year old male. fig. 11. (left) an extracted mandibular left first molar having an extra root radix entomolaris. (right) radiograph of mandibular right first molar showing no extra root radix entomolaris. case is a 50 year old male. fig. 12. (left) periapical radiograph showing the presence of c-shaped root on the mandibular left second molar. (right) radiograph of the mandibular right second molar showing two separate roots. case is 22 year old female. report 8 a 36 year old male reported for full crown restoration of the mandibular right second molar, and he also had sensitivity in the mandibular left second molar. a diagnostic periapical radiograph was taken for both mandibular right and left second molar. it was concluded that root canal treatment in the mandibular right second molar was indicated, and a full crown restoration was undertaken. for the mandibular left second molar, sensitivity was due to cervical abrasion and a conservative treatment of desensitizing toothpaste was prescribed followed by evaluation at three months. from the periapical radiograph (fig. 8a), it was noted that the mandibular right first molar had an extra root , a radix entomolaris, whereas the contralateral tooth (fig. 8b) had only two roots. report 9 a 19 year old male was referred for root canal treatment of the mandibular right first molar. on clinical and radiographic examination a diagnosis of irreversible pulpitis was made and the subject was advised to have root canal treatment. it was noted on the periapical radiograph that the mandibular right first molar had an extra root radix entomolaris (fig. 9a). on the contralateral tooth (fig. 9.b) there were only two roots. report 10 a 32 year old male was referred with pain and deep caries on the mandibular right first molar; he was advised for root canal treatment. he rejected this, and the tooth was extracted. it was noted after extraction that the tooth had an extra root, a radix entomolaris (fig. 10b). the contralateral periapical radiograph showed that that tooth had only two roots (fig. 10.a). report 11 a 50 year old male was referred for root canal treatment of the mandibular left first molar, but the man wanted the tooth extracted. after extraction, it was noted that the tooth had an extra root, a radix entomolaris (fig. 11a). the contralateral periapical radiograph was taken, and it showed that there were only two roots (fig. 11b). based on ribeiro and consolaro’s (1997) classification of radix entomolaris curvature, cases 5, 6, 7, 8, 9 had type i curve, case 10 and 11 had type ii curve. mandibular second molars c-shaped root configuration report 12 a 22 year old female with a complaint of pain in the mandibular left first molar was diagnosed with irreversible pulpitis, and root canal treatment was undertaken. the periapical radiograph disclosed that the 20 mandibular left second molar (fig. 12a) had a c-shaped root configuration. according to the classification of fan et al. (2004), it was a type i. the contralateral tooth (fig. 12b) had two separate roots. report 13 a 43 year old male reported to the department with a complaint of postoperative pain after a class i amalgam restoration on the mandibular right second molar. a periapical radiograph was taken, and it was concluded that pain was due to occlusal interference which was relieved. it was noted on the periapical radiograph that this tooth (fig. 13a) had a c-shaped root configuration. according to fan et al. (2004), the root was type i. a contralateral radiograph (fig. 13b.) was taken, and that tooth had two separate roots. report 14 a 34 year old female with a complaint of pain in the mandibular right first molar was referred for root canal treatment. this tooth had two separate roots (fig. 14b). the contralateral tooth had a c-shaped root configuration (fig. 14a). according to fan et al. (2004), the root was of type i. report 15 a 37 year old male reported with a complaint of pain in the mandibular left second molar. he was advised for root canal treatment, but he was not willing, and elected to have the tooth extracted. it was fond that this tooth had a c-shaped configuration (fig. 15a). according to fan et al. (2004), the root was of type ii. a contralateral periapical radiograph (fig. 15b.) showed that the antimere had two separate roots. presence of a c-shaped root was diagnosed from the radiograph according to the criteria of fan et al. (2004) of having a fused root, presence of a longitudinal groove on the root, and our assessment of the coronal, middle and apical third of root canal indicated the presence of c-shaped root. mandibular second molars presence of an extra root (radix entomolaris and radix paramolaris) report 16 a 23 year old female was referred for root canal treatment on the mandibular right second molar. the tooth was diagnosed with irreversible pulpitis, and root canal treatment was undertaken. based on the diagnostic periapical radiograph that this tooth had an extra root, a radix entomolaris (fig. 16a), which was confirmed during root canal treatment (fig. 16b). a contralateral radiograph showed that that tooth had two separate roots (fig. 16c). report 17 a 45 year old male reported with the complaints of pain in mandibular left second molar, and he was diagnosed with irreversible pulpitis and root canal treatment was undertaken. the periapical radiograph showed that this molar had an extra root radix entomolaris (fig. 17a) and this was confirmed during root canal treatment (fig. 17b). the radiograph of the contralateral tooth showed that it had a fused root (fig. 17c). based on the classification by ribeiro and consolaro (1997), cases 16, 17 had type i curvature. fig. 13. (left) radiograph showing the presence of a c-shaped root on the mandibular right second molar. (right) radiograph of the mandibular left second molar showing two separate roots. case is 43 year old male. fig. 14. (left) radiograph showing the presence of a c-shaped root on the mandibular left second molar. (right) radiograph of the mandibular right second molar showing two separate roots. case is a 34 year old female. fig. 15. (left) extracted mandibular left second molar having a c-shaped root. (right) radiograph of the mandibular right second molar having two separate roots. case is a 37 year old male. i.a. sherwood and p.g. reddy 21root asymmetry fig. 16. (left) preoperative diagnostic radiograph showing presence of a radix entomolaris on the mandibular right second molar. (center) post-obturation radiograph confirming the presence of a radix entomolaris on the mandibular right second molar. (right) radiograph of mandibular left second molar showing only two roots. case is a 23 year old female. fig. 17. (left) preoperative diagnostic radiograph showing presence of acradix entomolaris on the mandibular left second molar. (center) post-obturation radiograph confirming the presence of a radix entomolaris on the mandibular left second molar. (right) radiograph of the mandibular right second molar showing fused roots. case is a 45 year old male. fig. 18. (left) an extracted mandibular right third molar with a radix paramolaris. (right) radiograph of the mandibular left third molar showing only presence of two roots. fig. 19. (left) an extracted mandibular left third molar with a radix entomolaris. (right) radiograph of the mandibular right third molar showing only presence of two roots. case is a 54 year old male. mandibular third molars report 18 a 46 year old male was referred for root canal treatment of the mandibular right third molar, but because of inadequate mouth opening after consulting with the referring doctor it was decided to extract the tooth. inspection showed that the molar had three roots with an extra root, a radix paramolaris (fig. 18a). the contralateral tooth (fig. 18b) had only two separate roots. report 19 a 54 year old male reported with a complaint of pain in the mandibular left third molar. on examination the subject was diagnosed with irreversible pulpitis, and root canal treatment was recommended. but the patient was unwilling, and this third molar was extracted. this third molar had an extra root, a radix entomolaris (fig. 19a). the contralateral radiograph disclosed that the tooth had two separate roots (fig. 19b). report 20 a 21 year old male was referred with a complaint of pain in the mandibular left third molar. on examination, a diagnosis of irreversible pulpitis due to carious pulp exposure was made, and root canal treatment was recommended. from the panoramic radiograph (fig. 20) the mandibular right third molar had an extra root radix paramolaris. the contralateral tooth had only two separate roots. based on ribeiro and consolaro’s (1997) classification of radix entomolaris curvature, cases 18, 20 had type iii curve and case 19 had type i curve. maxillary second molars report 21 a 22 year old female was referred with a complaint of pain in both maxillary right and left second molars. on examination, a diagnosis of irreversible pulpitis with carious pulp exposure was made for both teeth. it was noted from the periapical radiograph of the maxillary left tooth (fig. 21a) that its palatal root outline was blurred and an extra palatal root canal was suspected. an extra palatal root canal in the maxillary left second molar was confirmed during treatment (fig. 21b). the contra lateral radiograph revealed that that tooth had only one palatal root canal (fig. 21c). based on vertucci ‘s (1984) root canal classification, it was a type iv canal configuration. discussion the variability of root canal morphology and root numbers represents a challenge to both endodontic 22 diagnosis and treatment. besides the root canal variability, the fluctuating asymmetry presented in these cases reiterates the need for the observer to have a greater understanding of root morphology. fluctuating asymmetry in root form has been reported and studied exclusively in very limited ways. bilateral asymmetry has been reported for each group of teeth from different populations, rather than reporting from one group and studying bilateral asymmetry in that population for various tooth types. this is the first time that a case report is presented with fluctuating asymmetry in root aberrations being highlighted. review of literature by cleghorn et al. (2007) reports that incidence of mandibular second premolars with two separate roots is very low and it has been put at an average of 0.4%. in a study by iyer et al. (2006) among a south indian group it was concluded that mandibular second premolars with two roots had an incidence of 6.2%, but the study failed to mention how the radiographs were interpreted for root variations. also, in the same study, bilateral occurrence of root variation was put at 3.2% but there is no mention which type of root aberrations were encountered or for on which mandibular premolar was affected. this bilateral incidence of 3.2% is much lower than reported by sabala et al. (1994) for bifurcated mandibular second premolar root, which he reported it at 54.5% in a caucasian population. in contrast to the study by iyer et al. (2006), the extrarooted mandibular second premolars in the present study occurred only unilaterally. in agreement with iyer et al. (2006) where it was reported that after vertucci type i, the type iv canal had the highest incidence, in the present cases all the mandibular second premolars with an extra root had vertucci type iv canals. the incidence of three-rooted mandibular first molars in an indian group has been reported at 5.97%, and bilateral occurrence of this aberration only at 37.14% (garg et al. 2010). in agreement with the present study, cases presented here only occurred unilaterally. the c-shaped mandibular root configuration in an indian group has been reported at 7.5% of all extracted teeth examined; bilateral incidence of this root aberration has not been mentioned in that study (neelakantan et al. 2010). sabala et al. (1994) reported that, in a caucasian group, the bilateral occurrence of a c-shaped root in mandibular second molars is 72.7%. in contrast to this study, we found four cases of mandibular second molars with a c-shaped root occurring only unilaterally. a mandibular second molar with three roots has been reported for an indian group at 8.98% of all the extracted teeth examined, and bilateral occurrence of this root aberration has not been mentioned (neelakantan et al. 2010). in the neelakantan study, presence of an extra root was in the mesiolingual position; however, in the case presented here, the extra root was in the distolingual position (radix entomolaris). this extrarooted mandibular second molar occurred only unilaterally. a mandibular third molar with three roots has been reported with an incidence of about 5% in turkish and caucasian populations; bilateral occurrence of this aberration has not been mentioned (sidow et al. 2000; sert et al. 2010). the cases presented here occurred only unilaterally, and two cases had the extra root present lingually (radix entomolaris), and one case had the extra root present buccally (radix paramolaris). a study of variation in mandibular third molar root morphology is lacking for the indian population. maxillary second molars with two palatal canals have a low incidence at 1.4% for a caucasian group, and bilateral occurrence of this aberration has not been reported (peikoff et al. 1996). the one case reported here with two palatal canals occurred only unilaterally. maxillary second molar root canal variation for indian populations is lacking. very few cases of root aberrations record the bilateral occurrence of root number (de moor 2002). to our knowledge, the only study that exclusively fig. 20. a panoramic radiograph showing mandibular right third molar having extra root radix paramolaris and a mandibular left third molar showing two separate roots. case is a 21 year old male. fig. 21. (left) pre-operative diagnostic radiograph suggesting the presence of extra palatal root canal on the maxillary left second molar. (center) post-obturation radiograph confirming the presence of the extra palatal root canal on the maxillary left second molar. (right) radiograph of the maxillary right second molar showing only one palatal root canal. case is a 22 year old female. i.a. sherwood and p.g. reddy 23root asymmetry recorded bilateral occurrence of root variations from a caucasian population is the study by sabala et al. (1994), and this study concluded that root aberrations occur bilaterally approximately 60% of the time. this is in contradiction to the present case reports where all of the root aberrations were present unilaterally. this variation in unilateral occurrence of the root aberration may be due to differences in the populations reported. ethnic differences in root phenotypes are an established phenomenon (scott and turner 2008). root number and morphological studies for indigenous subgroups in india are very limited. except for one study about the incidence of three-rooted mandibular first permanent molars, others do not mention the bilateral occurrence of root aberrations or fluctuating asymmetry (garg et al. 2010). human diversity in india is defined by 4,693 different, documented population groups that include 2,205 major communities, 589 segments and, 1,900 territorial units spread across the country (singh 1988). structuring of the subgroups has been reported in a genetic study (kashyap et al. 2006). since tooth and root development is strongly controlled by genetic factors, a more detailed study of root variations in different subgroups in india is warranted. a detailed study about root variations in maxillary and mandibular premolars and molars and their bilateral occurrence in a tamil speaking population in madurai, south india; is being undertaken by the authors through the department of anthropology, university of madras. conclusions 1. from the case reports presented here it is seen that for the tamil speaking population group in madurai, south india, fluctuating asymmetry is occurring for various types of root aberrations in permanent premolars and molars. 2. fluctuating asymmetry in root aberrations will be of importance to clinical dentists, dental anthropologists and dental morphologists. 3. a more detailed study on the incidence of root aberrations in permanent premolars and molars of local population group is necessary with greater emphasis on occurrence of fluctuating asymmetry for root aberrations. references cited baume rm, crawford mh (1979) discrete dental asymmetry in mexico and belize. j dent res 58:1811. carlsen o, alexandersen v (1990) radix entomolaris identification and morphology. scand j dent res 98:363-373. carlsen o, alexandersen v (1991) radix paramolaris in permanent mandibular molars: identification and morphology. scand j dent res 99:189-195. cleghorn bm, christie wh, dong cc (2007) the root and root canal morphology of the human mandibular second premolar: a literature review. j endodont 33:1031-1037. de moor rjg (2002) c-shaped root canal configuration in maxillary molars. int endodont j 35:200-208. dibennardo r, bailit hl (1978) stress and dental asymmetry in a population of japanese children. am j phys anthropol 48:89-94. fan b, cheung gsp, fan m, gutmann jl, fan w (2004) c-shaped canal system in mandibular second molars: part ii—radiographic features. j endodont 30:904-908. garg ak, tewari rk, kumar a, hashmi sh, agarwal n, mishra sk (2010) prevalence of three rooted mandibular permanent first molar among the indian population. j endodont 36:1302-1306. garn sm, lewis ab, kerewsky rs (1966) bilateral asymmetry and concordance in cusp number and crown morphology of the mandibular first molar. j dent res 45:1820. iyer vh, indira r, ramachandran s, srinivasan mr (2006) anatomic variations in mandibular premolars in chennai population. indian j dent res 17:7-10. kashyap vk, guha s, sitalaxmi t, bindu gh, hasnain se, trivedi r (2006) genetic structure of indian populations based on fifteen autosomal microsatellite loci. bmc genetics 7:28-36. kieser ja. groeneveld ht, preston cb (1986) fluctuating dental asymmetry as a measure of odontogenic canalization in man. am j phys anthropol 71:437444. kieser ja, groeneveld ht (1988) fluctuating odontometric asymmetry in an urban south african black population. j dent res 67:1200. lundström a (1961) some asymmetries of the dental arches, jaws and skull, and their etiological significance. am j orthod 47:81-106. lundsröm a (1963) tooth morphology as a basis for distinguishing monozygotic and dizygotic twins. am j hum genet 15:34-43. neelakantan p, subbarao c, subbarao cv, ravindranath m (2010) root and canal morphology of mandibular second molars in an indian population. j endodont 36:1319-1322. noss jf, scott gr, potter rh, dahlberg aa (1983) fluctuating asymmetry in molar dimensions and discrete morphological traits in pima indians. am j phys anthropol 61:437-445. peikoff md, christie wh, fogel hm (1996) the maxillary second molar: variations in the root number of roots and root canals. int endodont j 29:365-369. ribeiro fc, consolaro (1997) importancia clinica antropologica de la raiz distolingual en los molars inferiores permamented. endodoncia 15:72-78. sabala cl, beneati fw, neas br (1994) bilateral root or root canal aberrations in a dental school patient 24 population. j endodont 20:38-42. schafer e, breuer d. janzen s (2009) the prevalence of three-rooted mandibular permanent first molars in a german population. j endodontics 35202-205. scott gr, turner cg ii (2000). biological considerations: ontogeny, asymmetry, sex dimorphism, and intertrait association. in: scott gr, turner cg ii, editors. the anthropology of modern human teeth. dental morphology and its variation in recent human populations. bristol, uk: cambridge university press, p 96-105. scott gr, turner cg ii (2008) history of dental anthropology. in: irish jd, nelson gc, editors. technique and application in dental anthropology. new york: cambridge university press, p 10-35. sert s, sahinkesen g, topcu ft, eroglu se, oktay ea (in press) root canal configurations of third molar teeth. a comparison with first and second molars in the turkish population. aust endodont j. sidow sj, west la, liewehr r, loushine rj (2000) root canal morphology of human maxillary and mandibular third molars. j endodont 26:675-678. singh ks (1988) india’s communities. people of india. national series volume iv. india. new delhi: oxford university press. townsend gc (1981) fluctuating asymmetry in deciduous dentition of australian aboriginals. j dent res 60:1849. tu mg, tsai cc, jou mj, chen wl, chang yf, chen sy, cheng hw. (2007). prevalence of three-rooted mandibular molars among taiwanese individuals. j endodont 33:1163-1166. van valen l (1962) a study of fluctuating asymmetry. evolution 16:125-142. vertucci fj (1984) root canal anatomy of the human permanent teeth. oral surg oral med oral path oral rad endodont 58:589-599. walker rt, quackenbush le (1985) three rooted lower first permanent molars in hong kong chinese. br dent j 159:298-299. wetherell j, winning t, townsend gc (2004) localized asymmetry in human dental crown form—an interesting case. dental anthropology 17:18-23. i.a. sherwood and p.g. reddy daa subscription the secretary-treasurer of the dental anthropology association is dr. loren r. lease of youngstown state university. dr. loren r. lease department of sociology and anthropology youngstown state university one university plaza youngstown, ohio 44555 usa telephone: (330) 941-1686 e-mail: lrlease@ysu.edu dental anthropology now is published electronically and e-mailed to all members as a pdf. if you also want to receive a hard copy, be sure to make this clear on the membership form at the daa website or contact loren. speed communication about your membership by contacting loren directly (other officers may not have current membership information). weets 2009.1 65 dental morphological traits have long been recognized for their importance as phenotypic expressions of genetic differences between human groups. variations in root and enamel structure were noted in the past by dentists, natural historians, and anatomists (e.g., von carabelli, 1842; owen, 1845; tomes, 1889). physical anthropologists and dental anthropologists have continued to discover, describe and categorize new forms of dental trait variation (hrdlička, 1920; gregory and hellman, 1926; weidenreich, 1937; dahlberg, 1950; morris, 1975; scott, 1977; morris et al., 1978; harris and bailit, 1980; burnett, 1998; yamada et al., 2000; correia and pina, 2002; edgar and sciulli, 2004). rates of expression for many morphological traits have been recorded in various human population groups. these data have been used to search for patterns of affinity between world regional groups since the beginning of the discipline (e.g., hrdlička, 1921; hellman, 1929; dahlberg, 1945a, carbonell, 1963; morris, 1970; scott, 1980; scott and turner, 1997; hanihara, 2008). but there has been a general imbalance in information for these comparisons. populations of eastern asia, the americas and the pacific have received much attention over the years (e.g., wissler, 1931; kraus, 1959; suzuki and sakai, 1964; kolakowski et al., 1980; haydenblit, 1996; swindler and weisler, 2000; tocheri, 2002, matsumura and hudson, 2005). fewer studies of european (e.g., jørgensen, 1955; axelsson and kirveskari, 1977; toth, 1992; ullinger, 2002, coppa et al., 2007) and african (e.g., hassanali, 1982; irish, 1997; guatellisteinberg et al., 2001; irish, 2005) groups have been undertaken. while the study of tooth morphology has a rather lengthy history as a sub-field of physical anthropology (scott and turner, 1988; dahlberg, 1991; scott and turner, 1997), it is likely that discoveries of novel traits or under-reported variation will be made as new groups, especially in these less-studied regions of the world, are investigated. it appears that previously unreported variation in an enamel morphological character exists in ancient populations of ireland. the author noted this variation during a dental anthropological research project that sought to a promising mandibular molar trait in ancient populations of ireland jaimin d. weets* state university of new york at potsdam, ny 13676 abstract a novel morphologic feature on the human dental enamel of the permanent mandibular molars is described. the character, named mmpt (mandibular molar pit-tubercle), is situated mesial and occlusal to the position often occupied by the protostylid on the buccal aspect of cusp 1. three grades of variation, a pit, a groove, and a tubercle were observed, described and categorized for study. the study groups consisted mainly of archaeological specimens from ireland, representing approximately 5,000 years of prehistoric and early historic populations on the island, dating from the neolithic (ca. 4,000-1,800 b.c.) through the early christian era (ca. a.d. 400-1170). all lower molars (representing 432 individuals) were studied, ranging from 129 to 179 scorable molars depending on tooth type. *correspondence to: jaimin d. weets, department of anthropology, 129a macvicar hall, 44 pierrepont avenue, suny potsdam, potsdam, ny 13676 e-mail: weetsjd@potsdam.edu grant sponsorship: this research was made possible by grant ay2001/10 from the heritage council of ireland, grants from research and graduate studies office of the pennsylvania state university, research and sponsored programs suny potsdam, united university professions suny potsdam and two hill grants from the pennsylvania state university. the third molar more commonly expressed all forms of mmpt than the first or second molars, with approximately 30% of all third molars exhibiting a form of mmpt (28% of lower left third molars and 33% of lower right third molars). the most commonly expressed form of mmpt was grade 1, the pit form, most commonly on third molars. individual viking specimens from ireland also exhibited mmpt, and the trait appears to be present in east asian modern humans at a markedly lower rate of expression, and in homo pekinensis. further research will clarify any relationships between mmpt, paramolar tubercles, paramolar structures and the protostylid, as well as the utility of mmpt in dental anthropological biodistancing studies. dental anthropology 2009;22(3):65-72. 66 assess, through the use of the arizona state university dental anthropology system (asudas), the presence of large-scale migrations in ancient time periods of ireland (weets, 2004). while recording morphometric variation in specimens from several times periods dating from ireland’s neolithic (ca. 4,000-1,800 bc) to its early christian era (ca. ad 400-1170), an indentation in the enamel crown was first noted on the buccal surface of heavily fragmented and cremated permanent mandibular molars from multi-component megalithic tomb sites. initially, this indentation was thought to be a variant of a weak form of the protostylid, which simply had not been described in publications on the asudas (turner et al., 1991). in addition, the indentation often was not noticed because it was not in the correct location for a protostylid, which was one of the traits scored in the broader research project. eventually, the discovery of an individual with both a weak grade of protostylid and this indentation on the mandibular molars prompted a closer investigation of this characteristic (fig. 1). observing several specimens, it was found that the indentation was most often in the form of a small pit; a pinpoint circular area of enamel agenesis situated a good distance mesial from the buccal groove. the pit tends to be located high on the buccal surface of the lower molars, suggesting a high likelihood for destruction of the character with even moderate buccally-directed lower tooth wear. this pit differed significantly from the asudas grade 1 buccal pit of the protostylid, located in the buccal groove, as depicted on the asudas protostylid cast and described by turner et al. (1991). considering its most common form and the geographic setting, it was noted by the author as the “irish mandibular molar pit” (immp) during data collection and in publication of his ph.d. thesis (weets, 2004). the character, in all its forms, will be referred to as mmpt (mandibular molar pit-tubercle) for the remainder of this article. this label encompasses the range of variation; it avoids ethnic labeling commonly seen in the asudas system; and it allows for any relationship with complex forms of paramolar tubercles that future research may reveal. the morphological variation morphological variation was categorized into three grades that represented the most commonly observed forms of the trait. assuming that mmpt was either a new trait or had not been reported, other less common forms were assigned to intermediate grades. the intent in the formation of three major grades and of intermediate grades was to provide the fullest description of the trait to inform dental researchers. the accumulation of more data on mmpt variation will likely show some of the intermediate or major grades to be superfluous for biodistancing studies. for those who wish to incorporate the mmpt into a biodistancing study, although this may be premature, the author would suggest application of the same methods as are used with the asudas. only the three major grades of mmpt would be used, with systematic assignment of intermediate variation to the lower grade of variation (e.g., mmpt grade 1-2 assigned to mmpt grade 1) or, in a case of identifying presence of the trait, assignment to the first major grade (i.e., mmpt grade 0-1 is assigned to mmpt grade 1). it may be that mmpt proves to have rather clear gradations in morphology that account for its full range of variation, so that a graded plaque for the asudas could be produced. more more research on other populations is necessary to ultimately refine these embryonic categorizations of mmpt variation described below. fig. 1. grade 1 of mmpt present on second and third left lower molar as shown by downward-pointing arrows (buccal view). note presence of a weak form of the protostylid on second molar as shown by upwardpointing arrow. mesial is to the left of the photograph. fig. 2. grade 2 of mmpt on lower left third molar (buccal view). j.d. weets 67 grade 1 of the feature was assigned to the aforementioned small pit, located mesially and high on the buccal surface of cusp 1 of the lower molars (fig. 1). the pit was approximately 0.5 to 1 mm in depth. it was often located approximately 1-2 mm below the intersection of the buccal and occlusal planes, and approximately 1-2 mm from the intersection of the mesial and buccal faces. while the vast majority of pits encountered during the study were consistent in their location, depth and form, it was not always easy to detect the presence of the character. several individuals had a slight depression or indentation in the position often occupied by the pit. these were categorized as grade 0-1 of mmpt to acknowledge what appeared to be a weak expression of the pit form of the trait. grade 2 was a groove with its superior terminus approximately in the position often occupied by a grade 1 pit. from this point, the groove ran in a distalinferior direction at approximately a 30-45 degree angle to the occlusal plane (fig. 2). in some cases, the superior terminus was a pit with the groove extending in an inferior, distal direction from it. there were a handful of cases where the groove was quite short in its inferior-distal extension, making the “mouth” of the pit elongated. these were classified as grade 1-2. grade 3 has the form of a tubercle without a free apex. fig. 3 portrays this tubercle, situated mesially on the buccal surface. this photograph shows the strongest expression of a grade 3 cusp that was encountered during the study. note that there is no involvement with the tooth’s buccal groove (between cusps 1 and 3), even though the mmpt cusp is rather sizeable. in fact, though not quantified, there seemed to a relatively common tendency in these specimens from ireland for a very weak expression of the buccal groove, or complete lack of the buccal groove, on lower molars. there were other expressions of the character greater than grade 2 that appeared to be the beginning of the tubercle present in grade 3 (fig. 3). from the position occupied by the pit in grade 1, a groove ran inferiorly, giving the appearance of a small tubercle separating from the buccal face (fig. 4). situated about 1 mm distal to this groove was a pit. this pit was not in contact with the buccal groove as a protostylid would be, but the pit was lower on the buccal plane of the crown and more distally-situated than the pit from grade 1. it appears to demarcate the distal side of a weak tubercle, though not as well-formed as in grade 3 (fig. 3). several cases were encountered that were placed in this grade 2-3 category. it should be noted that even with categorization of mmpt, distinguishing between mmpt and the protostylid could be difficult. in three cases in the study, distally-directed grooves originating from areas high on the buccal surface of cusp 1 intersected the buccal groove separating cusps 1 and 3. if one were to have no knowledge of the mmpt character, these grooves intersecting the buccal groove would be most likely assigned to a form of the protostylid. because of the uncertainty in assignment, these cases were subsequently dropped from consideration in this study as forms of mmpt, and in the greater study as protostylids, though all three cases seemed to be more related in form to the protostylid. further research on the mmpt trait may provide clues helpful in discerning its more complex forms from those of the protostylid. fig. 3. grade 3 of mmpt on the lower left third molar of this individual (buccal view). the left arrow points to the mesial groove, and the right arrow points to the distal groove. in combination, these two grooves are marginal limits of this feature. fig. 4. lower right second molar exhibiting grade 2-3 of mmpt (buccal view). note the distally-situated pit mesial to the buccal groove and the sulcus forming at the mesial aspect of the enamel crown. mesial is to the right of the photograph. mandibular molar trait in ireland 68 geographic and temporal distribution a review of the literature revealed no report of the range of morphological variation described above for the mmpt. in response to a query, dr. christy turner (pers. comm.) kindly brought to the author’s attention an illustration of a similar-looking character on plate xvi (fig. 139b of sinanthropus 36) of weidenreich’s (1937) classic work on sinanthropus pekinensis. however, no written description of that character could be found in weidenreich’s work. looking further it seemed that other plates also had drawings depicting what appeared to be the same character. these include plates xviii (fig. 148b of sinanthropus 99), xix (fig. 172b of sinanthropus 114) and xx (fig. 177b of sinanthropus 52). dr. turner (pers. comm.) also commented that he had observed the character before in his research but had found them at such a low percentage in asian and asian-derived populations, where he has done much of his research, that he had not pursued it further. dr. joel irish (pers. comm.), in a discussion of photographs of mmpt with the author, commented that he had recently observed the pit form of mmpt in a euro-american male student in alaska, but did not know what the character was when he observed it in that individual, nor had he encountered it before in his research, which includes a number of african groups. paramolar tubercles although the range of variation of mmpt does not seem to have been described, publications about other traits appearing on lower molars in the general location of mmpt give cause for caution in suggesting that the trait is unreported. dahlberg states “the paramolar cusp of bolk, which is found occasionally on the mesial portion of the buccal surface of lower molars, occurs but rarely on the first molar, more often on the second and third” (1945a, p. 682). bolk (1916), in his description of the paramolar tubercle, or paramolar cusp, was not only talking about a cusp forming on the buccal surface of lower molars, but also on the buccal surface of upper molars. as summarized by dahlberg (1945b), bolk’s contention was that supernumerary teeth, called paramolars, which occasionally appeared buccal to and between the first and second, and second and third molars, were atavisms representing a fuller set of posterior deciduous dentition that had been lost in evolution. these paramolars, when they were not expressed as supernumerary teeth, were thought by bolk to sometimes join with the permanent molars during development, thus resulting in a cusp found on the anterior-buccal portion of the second and third molars. it was further argued by bolk (1916) that he had never seen a paramolar tubercle on a first molar in his study of 20,000 cases. in contrast, dahlberg (1945b) provided several examples of bolk’s paramolar tubercle on lower first molars, as well as an example of paramolar tubercles on all six lower molars. also, to provide for better terminology, dahlberg (1945b) suggested that bolk’s paramolar cusp be called a “parastyle” on upper molars and a “protostylid” on the lower molars. these are two traits that are, of course, present in the asudas. in his 1950 article, dahlberg returned to the subject and further refined his definition of the protostylid: (1) that it is unrelated to other analogous paramolar structures known generally as “paramolar cusps,” (2) that it is associated with the buccal groove, and (3) that it occurs much more commonly on first mandibular molars than do other paramolar structures. with his concentration on the protostylid, dahlberg left other paramolar cusps an open question. almost 50 years later, scott and turner (1997, p. 47, 53) discuss the parastyle of the upper dentition and state that there is little known about some paramolar structures and there is a lack of research on these traits. investigating what has been published on paramolar tubercles, bolk (1916) provides a number of photographs of paramolar cusps in the upper and lower dentition, but the majority is from an occlusal perspective. while there are clear examples of cusps arising on buccal surfaces, it is impossible to see exactly their expression on the buccal surface and how exactly they differ from protostylids because of the occlusal perspective. one photograph (bolk’s fig. 15) shows the buccal surface, but the tubercles are of much stronger expression than the variation exhibited in ireland, and some have involvement with the buccal groove. therefore, there is still quite a question of how exactly these structures are related. interestingly, there is a third molar in bolk’s fig. 22, although he did not mention it, where a pronounced anterior buccal cusp with no buccal groove involvement is portrayed. while some examples of bolk’s paramolar tubercle are likely to be strong expressions of mmpt, there appears to be no previous published information on the range of variation of this mesiobuccal structure as it is exhibited in ancient dentition from ireland. methods human remains from ireland’s neolithic (ca. 4,0001,800 b.c.), bronze age (2000-900 b.c.), iron age (700-100 b.c.) through its early christian era (ca. a.d. 400-1170) was the target group of the greater research project. also included in this research were a few remains from viking burials in ireland, dating from contexts after ca. a.d. 830. mallory and o’donnabhain (1998) provide an inventory of archaeological sites known to have yielded skeletal remains from these irish time periods and where they are currently curated. their document served as a guide for selection of sites, and it was the intent of the greater research project to observe all of their listed sites within these time periods. j.d. weets 69 in this particular research on mmpt variation, skeletal remains from the holdings of the national museum of ireland in dublin (nmi), the department of archaeology at university college, galway (ucg), the department of anatomy at queen’s university, belfast, northern ireland (quba), and the department of archaeology at queen’s university, belfast (qub) were examined. nmi holds the majority of all archaeological human remains from the island, and most of the teeth from this study were examined there. across a time span of a few thousand years, there were various mortuary programs, and these distinctive programs sometimes existed at roughly contemporaneous periods. cremated, secondary burials and inhumed remains were encountered. deposition of multiple individuals was present in a number of contexts, especially from pre-christian time periods. there were also a sizeable number of individual inhumations with teeth intact in the mandible, especially from the bronze age and the early christian period. in order to systematically study and record mmpt, individuals were separated and dental elements sorted. all lower molars encountered were inspected for the presence of mmpt. detailed notes describing mmpt were entered in the database on each molar. in addition, the character was assigned one of the three grades using written descriptions, direct comparisons of molars with mmpt variation, and reference to digital photographs. intermediate examples of variation were assigned grades illustrating the range of variation they encompassed (0-1,1-2, 2-3). degree of wear was also collected on all molars. in any case where a tooth was too worn, damaged in some manner that the buccal surface could not be examined or were obscured by heavy soil matrix or calculus, the character was assigned a non-score. a 10x hand lens was used to observe trait variation in all lower molars. the final total of individuals with at least one lower molar was 432. the database was scanned for information collected on mmpt. in three cases, mmpt could not be discerned from expressions of the protostylid and these were dropped from the study. wear was often quite heavy; antemortem tooth loss was common; and heavy calculus was encountered rather frequently. these factors reduced the study sample by more than half, resulting in between 129 and 179 scorable molars depending on tooth type (table 1). results table 1 shows frequency rates of mmpt expression in all measureable ancient teeth from ireland. the strongest expression is in the third molars where approximately 3 out of 10 individuals exhibited the character (28% of lower left third molars and 33% of lower right third molars). the first and second molars show a decidedly low frequency of the trait with ranges between 0% and 3% of the sample with the character. the most common expression of mmpt is the pit form, with 10% of lower left third molars and 19% of lower right third molars exhibiting this grade 1. if one were to include the weak indentation form (grade 0-1) and the elongated pit/short groove form (grade 1-2) with grade 1, then 21% of lower left third molars and 26% of lower right third molars have grade 1 morphology. percentages for grade 2 show greater rates of expression of mmpt in the third molar over the first and second molars. in grade 2-3, second and third molars are essentially equal and in grade 3, rate of expression is essentially equal for right second and third molars (ca. 1%) with greater disparity in rate of expression between left second and third molars (0% vs. 2%, respectively). three viking specimens from ireland not listed in table 1 were also measured and had a similar percentage of expression—from this decidedly tiny sample—to that of the prehistoric and early historic groups. one specimen (eyrephort, co. galway) had grade 1 mmpt on its lower left third molar, while its first and second lower left molars had none. a second specimen (islandbridge, co. dublin) had no expression of the trait on its right third molar, the only lower molar representing this individual. the third individual (kilmainham, co. dublin) had two teeth, the left second and third lower molars, which could be scored. the trait present on these two teeth could not be distinguished from a protostylid. this was one of the three cases in the study where a distinction between a protostylid and mmpt could not be made. mandibular molar trait in ireland table 1. scorable ancient irish cases with percentages of character grade expressions by tooth tooth1 n grade 0 grade 0-1 grade 1 grade 1-2 grade 2 grade 2-3 grade 3 lm 1 170 100.0 0.0 0.0 0.0 0.0 0.0 0.0 rm 1 151 97.9 0.0 0.7 0.7 0.7 0.0 0.0 lm 2 178 97.7 0.6 1.1 0.6 0.0 0.0 0.0 rm 2 179 96.6 0.0 1.1 0.6 0.0 0.6 1.1 lm 3 131 71.6 0.8 10.2 9.8 5.3 0.0 2.3 rm 3 126 67.2 1.6 19.4 4.7 5.5 0.8 0.8 1codes are left (l) and right (r) sides. 70 discussion the frequency of expression of mmpt is promising for future application in dental anthropological studies. at least in ancient populations from ireland, it appears to occur at a rather high frequency, which is somewhat unusual for dental anthropological characteristics in european or european-derived populations. only traits such as upper second incisor interruption grooves, 4-cusped lower second molars, carabelli’s cusp, 2-rooted upper first premolars and 3-rooted upper second molars as described by scott and turner (1997) have rates of expression approximately as high or higher. many others have rates of expression in only 5-10% of a given european or european-derived population (scott and turner, 1997). one intriguing question is how mmpt is expressed in other populations. considering european populations, its appearance in at least one of three viking individuals, all of whom have been suggested to be from populations external to ireland based on either grave goods or burial context (nmi museum inventory files for eyrephort, kilmainham and islandbridge; mallory and o’donnabhain, 1998; waddell, 2000), promises a high probability that mmpt will be found in other european samples. it may be possible that one, two or all three of these individuals could be hiberno/norse rather than scandinavian viking, coming from intermarriage between indigenous irish and viking populations, and that the trait might be expressed in a given individual because of indigenous irish parentage. however, the most clear case of mmpt expression in these supposed viking individuals is seen in the eyrephort, co. galway specimen, who came from a single burial accompanied by a sword, dagger and shield boss of viking type (nmi museum inventory file) and has long been recognized by irish archaeologists as one of the clearest examples of a viking burial in ireland (waddell, 2000). joel irish’s (pers. comm.) recognition of mmpt in a euro-american student, though the exact descent of that student is not known, provides further evidence that mmpt may be a relatively common trait in european and europeanderived peoples. another question is the utility of the trait in discerning world regional samples from one another. it may not be possible in european or european-derived populations to use mmpt to distinguish geographic or temporal groups. but, based on a relatively high rate of occurrence in ancient populations of ireland, a very low rate of occurrence in east asia (c. g. turner, pers. comm.) and a trait that had not caught the eye of a researcher in his extensive study of african populations (irish, pers. comm.) it seems that mmpt would be useful in distinguishing world regional groups from one another. weidenriech’s (1937) depiction of what appears to be mmpt in homo pekinensis suggests that the trait could be useful in paleoanthropological studies as well. finally, there is the lingering question of the novelty of the mmpt. while no publication could be found that depicts mesiobuccal mandibular molar morphology ranging from a pit to a tubercle trait, it is certainly possible that these mesiobuccal pits, grooves and tubercles are weak expressions of what have been referred to as paramolar tubercles on the mandibular dentition (bolk, 1916), with the exclusion of all forms of the protostylid. interestingly, although bolk (1916) reported that he had never noted a paramolar cusp on the first molar, which matches well with the pattern of mmpt, he also states that it was much more commonly found on the second molar than on the third. this pattern apparently applied to both the upper and lower molars (bolk, 1916). this prevalence of bolk’s paramolar tubercles on the second molar runs contrary to the findings of mmpt expression in this study, where it is the third molar that had equivalent or slightly higher rates of expression than the second molar of grade 3 of mmpt, which is the closest form of variation to what might be viewed as a paramolar tubercle. kustaloglu’s (1962) research on upper paramolar tubercles (parastyles) suggests a potentially high degree of symmetry in rates of expression between mandibular and maxillary tubercles. data on the ancient irish remains shows parastyle frequency rates of expression of only 1.6%, 1.2% and 1.4% for the upper first, second and third molars, respectively. considering the higher grades of mmpt, grades 2-3 and 3, this pattern of upper and lower symmetry between a known and a potential paramolar structure holds. for the first and second molars on all grades of the mmpt, there are similarly low (or nonexistent) rates of expression that reflect the pattern of expression for the parastyle. however, in the lower grades of mmpt, when the third molar is considered, there is significant dissimilarity. furthermore, there was never an example of a similar mesiobuccal pit, groove or tubercle structure like the mmpt on the maxillary molars that might reflect the mmpt in the upper dentition of this study population. schulze discussed paramolar tubercles and structures: “they appear more frequently on the upper molars … favoring the second and third. as a rule, they are located on the mesiobuccal cusp but can occur farther distally. their size varies, and frequently a small depression or enamel groove is found in the corresponding place” (1970, p. 99). this last portion of the passage sounds very much like mmpt, but, reading further, schulze is discussing paramolar structures on both the upper and lower molars, the reference to enamel grooves apparently comes from a 1926 article by fabian on upper molars that schulze cites and in focusing on paramolar tubercles that could appear in the lower dentition “on the first molar and, rarely, on other teeth.” dahlberg’s 1950 article is cited where clearly the protostylid would be included among these paramolar tubercles (schulze, j.d. weets 71 1970, p. 100). what had appeared at first glance to be the best description of characters like mmpt awaits further research to distinguish connections and differences between mmpt, bolk’s paramolar tubercle and the protostylid. and, for that matter, further research of the upper molar parastyle may reveal greater variation in paramolar structures of the upper dentition. conclusions this report describes the mmpt that is expressed the buccal surface of the mesiobuccal cusp of lower molars. ths feature occurs in approximately 30% of specimens from ireland dating from the neolithic to the early christian period. it appears to have a wide geographic and temporal distribution, as it was present in a small sample of vikings from ireland, and, apparently, in specimens from ancient eastern asia, both modern human and older hominid species. the situation of the mmpt trait on the buccal surface of mandibular molars increases its likelihood of surviving dental attrition. its higher frequency of occurrence on third molars improves chances for observation relative to buccal traits on worn first and second lower molars. the mmpt also has the potential to be one of the more frequently exhibited dental traits known in european and european-derived populations. further study of mmpt will clarify its range of variation and determine what connections, if any, it has to bolk’s mandibular paramolar tubercle, the protostylid, or paramolar structures of the upper dentition. the forms of mmpt illustrated in this article suggest a trait that has promise for future dental anthropological studies. acknowledgements this research was made possible by grant ay2001/10 from the heritage council of ireland, grants from research and graduate studies office of the pennsylvania state university, research and sponsored programs suny-potsdam, uup suny-potsdam and two hill grants. i would like to thank a number of people for their assistance, insights and friendship that made this project a success: george milner, jim wood, dean snow, mark shriver, and deryck holdsworth from pennsylvania state university; patrick wallace, eamonn kelly, mary cahill, andy halpin and margaret lannin from the national museum of ireland; john waddell and angela gallagher from university college, galway; richard warner and sinead mccartan from the ulster museum, northern ireland; malcolm fry and linda canning from the department of the environment, northern ireland; eileen murphy and david heylings of queen’s university, belfast, and a special thanks to jim mallory of queen’s university for his insights, enthusiasm and bridges of communication with colleagues, and to he and his family for their hospitality. literature cited axelsson g, kirveskari p. 1977. the deflecting wrinkle on the teeth of icelanders and the mongoloid dental complex. am j phys anthropol 47:321-324. bolk l. 1916. problems of human dentition. am j anat 19:91-148. burnett se 1998. maxillary premolar accessory ridges (mxpar): worldwide occurrence and utility in population differentiation. ma thesis, arizona state university, 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anthropol sci 108:261-282. tocheri mw. 2002. the effects of sexual dimorphism, asymmetry, and inter-trait association on the distribution of thirteen deciduous dental nonmetric traits in a sample of pima amerindians. dental anthropology 15:1-8. tomes cs. 1889. a manual of dental anatomy: human and comparative. london: j. & a. churchill. toth t. 1992. on the frequency of shovel-shaped incisors in hungarians. in: smith p, tchernov e, editors. structure, function and evolution of teeth. london: freund publishing house ltd. p 491-499. turner cg ii, nichol cr, scott gr. 1991. scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in: kelley ma, larsen cs, editors. advances in dental anthropology. new york: wiley-liss, inc., p. 13-31. turner cg ii. pers. comm. letter relating dr. turner’s recognition of mmpt character in digital photos sent to him by the author and of similar characters in weidenreich’s work on sinanthropus pekinensis. february 25, 2002. ullinger j. 2002. early christian pilgrimage to a byzantine monastery in jerusalem—a dental perspective. dental anthropology 16:22-25. von carabelli g. 1842. anatomie des mundes. wien: braumuller und seidel. waddell j. 2000. the prehistoric archaeology of ireland. bray, co. wicklow, republic of ireland: wordwell ltd. weets jd. 2004 a dental anthropological approach to issues of migration and population continuity in ancient ireland. ph.d. thesis. the pennsylvania state university, university park. weidenreich f. 1937. the dentition of sinanthropus pekinensis: a comparative odontography of the hominids. peiping: palaeolontologica sinica. new series d, no. 1. whole series no. 101. wissler c. 1931. observations on the face and teeth of the north american indians. anthropol pap am mus nat hist 33:1-33. j.d. weets 55 dental anthropology 2021 │ volume 34│ issue 01 there is great public and academic interest in intentional body modification. interest is largely driven by the glimpse that bodily alterations offer into the belief systems of past and present societies. in focusing on the myriad populations that practice(d) intentional modification of the teeth, the edited volume, a world view of bioculturallu modified teeth, offers readers a fascinating collection of chapters that illustrate the worldwide and temporal variation of an ancient practice. four main types of intentional dental modification are discussed across 20 chapters: ablation (intentional tooth removal), filing, notching and incising, inlays (drilling the tooth to insert precious stones or metal), and tooth dyeing. the volume editors, scott burnett and joel irish, have the expertise and network to move such research in a much needed direction with the aim of pulling together population-level data rather than case studies of single individuals or sites, which have dominated the scholarly literature up to now. this approach fosters greater understanding of the social implications and biological consequences of intentional dental modification. the book is divided into four sections covering different geographic regions: i) africa, ii) europe and northeast asia, iii) southeast asia, australia, and oceania, and, iv) the americas. south america is, unfortunately, missing, though an introduction written by burnett and irish provides a useful overview and ample references to work done in this region. geographic coverage by the volume is, nonetheless, expansive. it is fitting that a foreword by clark spencer larsen and a conclusion chapter by george milner bookend the volume, as they published a widely read and highly regarded review of archaeological cases of dental modification in 1991. there is a nice mix of early, midand late career scholars such that the volume contains chapters by the ‘who’s who’ of dental anthropology but also brings newer researchers into the fold. as well, the authors come from different professional environments, including government ministries, museum curators, private companies, and various universities. within the overarching theme of population perspective, the chapters have different aims, which exposes the reader to a broad range of methods that are used to explore diverse questions. the chapters are well written, clearly organized and blessedly concise. the most commonly discussed topics are (i) improved diagnostic methods (especially to distinguish causes of tooth ablation), (ii) the possibility that tooth ablation in some african groups was done because tetanus or infantile fever caused lockjaw, (iii) the effect of dental modification on oral health, (iv) the tools and methods used to modify teeth along with the proficiency of the person who performed the procedure, (v) the association of modification with sex, age, status, family/lineage, population and other identity categories, (vi) the role of modification as a physical signal to people/groups within (intra-) vs. outside (inter-) the population, (vii) the origin of the practice especially in regard to cultural diffusion vs. independent invention, and (viii) the use of spatiotemporal patterns of modification to infer movement and interaction amongst past populations. the book is best suited to readers with some basic (bio)archaeological knowledge, but for the most part can also be understood by those without such knowledge. most chapters contain evocative photographs of modified teeth and, if anything, one could wish for more of these. other depictions of tooth modification are also compelling, including an image from the ancient egyptian tablet of terura depicting a man being fed through a hollow tube placed in an opening possibly left by ablated teeth that were removed because of lockjaw (in the chapter by bolhofner about ancient nubia) and a picture of an approximately 2000-year-old stone rain deity mask with clear evidence of inlays in the anterior teeth (in the chapter by mayes and colleagues about oaxaca, mexico). harvey and colleagues created useful drawings that reconstruct the face and smile of jomon individuals from japan with tooth ablation (to ‘flesh out the skulls’). many chapters include fascinating and informative accounts of tooth modification by past indigenous peoples and those with whom they came into contact (from sub-saharan africa, southeastern australia, western micronesia, mesoamerica, and ancient nubia) and the chapters on taiwan, by pietrusewsky and colleagues, and bali, by artaria, even include photographs of recent people undergoing tooth modification. a valuable feature of this book is two chapters that explore intentional dental modification in modern populations, one living in cape town, south book review a world view of bioculturally modified teeth. edited by scott e. burnett and joel d. irish. university press of florida. 2017. 368 pp., $110.00 (hardcover). isbn: 9780813054834. 56 dental anthropology 2021 │ volume 34│ issue 01 africa, in a chapter by friedling, and the other living on the island of java in indonesia, in a chapter by artaria. the ability to ask people why they chose to modify their teeth provides tremendous insight into what is often the most elusive question we have of past populations, which is “why did they do that?” respondents gave a variety of reasons for removing or filing their teeth, most commonly involving notions of beauty, identity, and custom. i would have appreciated a chapter about modern-day dental procedures common in western and other societies, often termed ‘cosmetic dentistry’, and including teeth straightening, whitening, replacement (i.e. veneers, caps including decorative gold crowns, bridges, dentures, etc.) and even the wearing of dental grills. such chapters would serve to lessen the ‘othering’ that can happen with a book like this, as many readers will associate the examples with foreign places and peoples, and not think about dental modification for non-therapeutic purposes as a practice that is common in their own society. the most common finding across populations that practiced dental modification is its occurrence during adolescence (circa 10-25 years of age), with the physical changes of puberty most closely tied to ceremonial events. other findings common across populations proved elusive, as the association of dental modification with sex, status, and other identity groups is quite variable. an unexplored avenue is the comparison of skeletal markers of repetitive physical activity, such as long-bone cross-sectional geometry or muscle entheses, among those with and without dental modification, to identify different task or occupation groups, especially involving differential mobility. as well, at sites with skeletons suitable for radiocarbon dating, bayesian modelling of each individual could illuminate fine-scale temporal patterns in dental modification. the chapters that explored the effect of dental modification on oral health, perhaps surprisingly, did not always find a significant increase in caries or infection rates, although authors note these findings need to be substantiated with tooth specific data and by taking into account confounding factors such as age, diet, and dental wear. radiographic and microscopic methods proved useful in detecting changes in the inner tooth layers (dentine and pulp) and alveolar bone. a future avenue to explore the impact of dental modification on oral health is via human and microbial biomolecules (proteins and dna) in calculus deposits. this volume demonstrates that isotopic methods can elucidate relationships between dental modification and aspects of identity, as shown by kusaka who used stable carbon and nitrogen isotopes to reconstruct dietary differences among different jomon sites; hedman and colleagues who used strontium isotope ratios to determine the birthplace of individuals with dental modification at cahokia; and newton and domett who reference oxygen and strontium isotope work being done to detect immigrants at several southeast asian sites. while there were no chapters in this volume that used ancient dna data to explore genetic affinity and dental modification patterns, such work has recently been done and will no doubt become more common in the future. all in all, the reader will undoubtedly come away with an appreciation of the wide range of insights, ranging from the ‘how’ to the ‘why’, that can be drawn by studying intentional dental modification. the editors and authors aptly demonstrate the utility of population-level investigations. as is often the case in bioarchaeology, much of the research raises just as many questions as answers. yet, with new research broaching ever more sophisticated questions, as seen in this volume, our understandings are sure to grow and improve. reference milner, g. r., & larsen, c. s. (1991). teeth as artifacts of human behavior: intentional mutilation and accidental modification. in m.a. kelley & c.s. larsen (eds.), advances in dental anthropology (pp. 357-378). new york: wiley-liss. andrea l. waters-rist department of anthropology university of western ontario 77 dental anthropology 2019 │ volume 32 │ issue 02 the medieval transylvanian oral condition: a case study in interpretation and standardization katie zejdlik 1* , jonathan d. bethard 2 , zsolt nyárádi 3 , and andre gonciar 4 1 anthropology and sociology department, western carolina university 2 department of anthropology, university of south florida 3 haáz rezső museum, odorheiu secuiesc, romania 4 archaeotek-canada llc., ontario, canada health, as a descriptive term, is commonly used in the bioarchaeological literature to indicate evidence of pathological modification on the skeleton. however, the world health organization includes mental and social factors, in addition to bodily disease states, as important to an assessment of health (who, 1999). reitsema and mcilvaine (2014) have added that a majority of pathological modifications observable in skeletal and dental tissues could have been caused by a myriad of conditions. within the more focused parameters of oral health, the lack of patient histories, clinical records, and environmental living conditions has resulted in inconsistent application of terminology, understanding of disease etiologies, and recording of observations in bioarchaeological contexts (pilloud & fancher 2019, this volume). what this means is that to understand the ‘health’ of a population, one must consider physical, mental, and social factors without access to patient histories, clearly understood etiologies, or standardized definitions among researchers. bioarchaeologists are suited to address this challenge through the application of a multifaceted approach that pieces together cultural and biological information. combined with the use of standardized language, communication between researchers can be improved and interpretations more accurately compared across sites. this paper examines pathological conditions of the oral cavity among medieval transylvanian székely communities as a case study to apply the vocabulary and definitions discussed by pilloud and fancher (2019) and to demonstrate the challenges of comparison between sites. furthermore, it contributes to the paucity of information available on archaeologically derived skeletal collections from eastern europe. abstract interpretation of dental ‘health’ in archaeologically derived skeletal assemblages is challenging due to the lack of patient histories, clearly understood pathological processes, broad etiologies, and cultural perceptions of health. furthermore, the language used in description of pathological conditions of the oral cavity condition is not consistent across researchers thereby resulting in challenging cross-site comparison. standardization of terms and description is necessary as proposed by pilloud and fancher (2018). this paper demonstrates the challenges associated with cross-site comparisons through an attempt to place medieval transylvanian székely peoples’ oral condition within a larger medieval cultural and biological framework. to do this, first, a review of medieval perceptions of dental health and treatment is provided. next, a total of 90 individuals recovered from two medieval székely cemeteries were analyzed for pathological conditions of the oral cavity. the results of the analysis were then compared to other medieval skeletal assemblages reporting on dental ‘health’. results show that conditions of the medieval oral cavity cannot be generalized and comparisons are further complicated by a lack of standardization in description and reporting thus supporting this volume’s call for standardization. results also show that conditions of the oral cavity are specific to time and place even between the two transylvania sites discussed. *correspondence to: katie zejdlik western carolina university cullowhee, nc 28723 kzejdlik@wcu.edu keywords: medieval; dental; health; székely; transylvania; archaeology 78 dental anthropology 2019 │ volume 32 │ issue 02 condition of the oral cavity: medieval cultural perspective human skeletal remains hold important information about the social and biological context in which a specific person navigated. interpretation of that individual’s lived experience begins with understanding the cultural context of the time. for the medieval individuals discussed here, an understanding of medieval medical practices is useful. healthcare in the middle ages was predominately influenced by hippocrates’s 5th century b.c. humoural theory. in his treatise, the nature of man, hippocrates stated that the body was composed of humours, or body fluids, specifically, blood, yellow and black bile, and phlegm. these humours corresponded with different conditions and seasons: blood, hot and wet, predominates in spring; yellow bile, hot and dry, in summer; black bile, cold and dry, in autumn; and phlegm, cold and wet, in winter (jouanna, 2012). it was thought that every person had a different make-up of humours; even organ systems within people had different humoural constructions and poor health resulted when the humours were out of balance. the noted greek physician, galen, later supported and expanded hippocrates’ work, which gave it the sustainable success that carried it into the enlightenment (jouanna, 2012; king, 2013). multiple other interpretations branched off hippocrates’ original idea but the vocabulary and general understanding of the humours remained prevalent in medieval understandings of health and medicine (jouanna, 2012; king, 2013). the broadly applied humoral theory extended into dentistry (anderson, 2004; bifulco et al., 2016). the medical school of salerno, italy was one of the most influential medical resources of the medieval period. in addition to general medicine, they paid attention to dentistry and domestic oral hygiene. trotula de ruggiero, a person of somewhat mythic status associated with the salerno school, is credited with writing the first treatise on oral hygiene (bifulco et al., 2016). she advocated deep dental cleaning and brushing, mouthwash, chewing of herbs for daily cleaning and pleasant breath, as well as remedies for gingivitis, halitosis, and tooth whitening. many of the ingredients she suggested are still used today in cosmetic and hygiene products (bifulco et al., 2016). though these practices are largely unobservable in skeletal remains, they indicate that medieval people were interested in oral care in addition to more visible and serious modifications. conditions of the oral cavity observable in the archaeological record include general tooth decay, dental caries, periapical lesions, and tooth loss. toothache, which could have several etiologies, the most treated problem in medieval dental medicine, was managed with everything from fumigations to oaths (anderson, 2004; bifulco et al. 2016). j. platearius, a doctor in the salerno school, wrote that dental pain was specifically a result of imbalanced warm and cold humours from the brain or stomach (cited in bilfulco et al., 2016). additionally, some of the doctors at salerno believed tooth decay was caused by odontalgic worms that caused pain with their movements, an idea that dates to sumerian texts from 5,000 b.c. gilbertus anglicus (c.ad 1240) also agreed that tooth worms caused dental pain and required balancing the humours (cited in anderson, 2004). dental caries and fistulae were treated with herbal concoctions placed as a paste within the cavity of the tooth (anderson, 2004) or by cauterizing the rotten dental pulp and sealing it with wax, which essentially destroyed the pulp chamber nerve supply (bifulco et al., 2016). dental care was limited to non-invasive treatment (anderson, 2004). dental extraction was rarely cited in the salerno documents because it was not a practice of physicians but rather “charlatans who practiced their profession in the streets and in open-air markets, and replacing the tooth with a tiny piece of wood or an iron bolt” (bifulco et al., 2016:2). the ‘charlatans’ were barber surgeons and willing to do surgery, unlike doctors. they often learned their skill through performing surgery on the war wounded or as an apprentice; though, many had no formal education, and most were illiterate. eventually surgery became a formalized profession and barbers were not allowed to provide surgical intervention except in cases of tooth extraction and blood-letting (pelling, 1998). access to barber surgeons was regulated by the catholic church and not accessible to females (lopez et al., 2012). those who could not access or afford a barber surgeon depended on prayer or pilgrimage as a means for a cure (anderson, 2004). medieval peoples understood that small infections of any type could become fatal if not attended to and took all available treatment precautions (pelling, 1998). in terms of actual oral heath, it is unknown what medieval peoples perceived as unhealthy. literature related to oral ‘health’ during the medieval period is often derived from skeletal assemblages and the interpretations of modern researchers. that is the problem with the casual use of the word ‘health’. it is temporally and socially compli79 dental anthropology 2019 │ volume 32 │ issue 02 cated to define. at best, researchers must anecdotally pull information from various types of knowing (images, educational documents, song, and folklore) to try to understand an ancient perspective. in the case of the medieval oral condition, dental medicine and hygiene made important advancements during the medieval period and from that, we argue, that we can infer that the numerous treatments for dental pain and dental hygiene resulted from medieval concern for oral care. condition of the oral cavity: medieval bioarchaeological perspective information derived from research on skeletal assemblages provides a data-driven perspective to complement the less direct information available from cultural sources like the examples discussed above. the bioarchaeological literature often reports on types and frequencies of dental modifications with reference to the social factors that might have impacted the results. these findings are then used to make an assessment about the dental, or overall, ‘health’ of the population represented by the skeletal assemblage. for instance, lopez and colleagues (2012) reviewed the diverse factors that contribute to various conditions of the oral cavity covering explanations from clinical processes, gendered access to dental care, consumption of cariogenic foodstuffs, and culture-specific food preparation techniques. they demonstrated through a comprehensive literature review that generalizations about etiologies cannot be made and that the interpretations must be heavily context dependent. lopez et al. (2012) investigated sex-differences in oral health from two medieval sites in spain and concluded that there were no sex-based differences in dental health. these findings mirror similar contexts in france (esclassan et al., 2009) and croatia (šlaus et al., 2011). however lopez et al. (2012) note that when compared to the modern age individuals (late 18th century), sex-based differences were evident. belecastro and colleagues (2007) investigated diet changes and health decline in response to large social and economic changes after the fall of the roman empire. the dentition of two temporally contiguous sites (roman imperial to early medieval) in central italy were investigated to make inferences about dietary practices across time. they concluded that overall protein consumption reduced after the decline of the roman empire and that the medieval diet consisting of higher carbohydrate intake led to an increase in dental wear, periapical lesions, and calculus. the lack of increased dental caries was thought to be due to the increased level of wear resulting from a harder and more fibrous diet, which required longer and stronger mastication. as the complicated morphology of the tooth wore away, there would be less opportunity for carious lesions to form; an interpretation supported by dental data from other medieval sites (caglar et al. 2007; chazel et al. 2005; esclassan et al. 2009). belecastro and colleagues (2007) also coupled dental data with pathological skeletal markers and evidence of infectious disease to conclude that while diet did not appear to change in significant ways, health conditions present during the roman imperial era continued and then worsened. the inverse relationship of high dental wear and low dental carious lesions was not found at other medieval sites investigating changes in dental data between medieval sites and other time periods (e.g, šlaus et al., 2011; srejić, 2001), which demonstrates the variability in the medieval oral condition. another example is demonstrated through frequency of carious lesions. low levels of carious lesions and dental wear were reported for a medieval coastal site in croatia (novak et al., 2012). rapid urbanization of the site during the late medieval period led to an increase in infectious disease indicators and overall reduction of health (novak et al., 2012). conversely, high levels of carious lesions and dental wear were present in two medieval, cemeteries from serbia (srejić, 2001). the cause of the high frequency was interpreted to be a result of food processing and poor oral hygiene. overall, there does not appear to be a general status of oral condition across the medieval period and conditions are highly specific to geographic, temporal, and social contexts. interpretations of ‘health’ range from multiple lines of evidence as discussed above to more limited interpretations about diet and comparison to other medieval sites (e.g, caglar et al., 2007; chazel et al., 2005; srejić, 2001). each author managed challenges associated with limited historical data, limited comparative sites, and a general lack of standardized recording and reporting methods. these were some of the hurdles faced when placing the transylvania case study sites into various comparative categories. biocultural context for the last seven years, our work has focused on documenting the lives of medieval and early modern transylvanian hungarians (bethard et al., 2019; molnár, 2001). the study area encompasses a 80 dental anthropology 2019 │ volume 32 │ issue 02 region of eastern transylvanian located inside the carpathian basin. it is currently home to over 600,000 people and called the székelyföld by the ethnic hungarian inhabitants who have lived there for nearly 1,000 years. in this study, two historically hungarian transylvanian cemeteries located 18.5km apart in harghita county, romania were analyzed (figure 1). the papdomb archaeological site in văleni (hungarian: patakfalva), romania designates the ruins of a medieval church and its associated burial grounds. the second archaeological site is a medieval cemetery located on the grounds of the catholic church in bradeşti (hungarian: fenyéd), romania. though inhabitants of both villages are identified as romanian citizens today, the whole of transylvania was not incorporated into the current political boundary of romania until the conclusion of world war i. for the last millennium, the inhabitants of both văleni and bradeşti have identified as hungarian, more specifically, as székely. for clarity of discussion, the sites will be referred to via their official archaeological site designators; papdomb and fenyéd. excavation of the patakfalva cemetery site began in 2014 as a salvage project per the request of the villagers. a collaboration between the inhabitants of patakfalva, the haáz rezső múzeum in nearby odorheiu secuiesc, and archaeotekcanada, llc was created to excavate and analyze the remains. the papdomb site was used repeatedly for several hundred years as indicated by historic records, temporally specific artifacts like coins, and evidence of burials truncated by later burials (figure 2). in general, people were interred in a supine, extended position with their heads to the west, feet to the east. body arrangement, soil stains left by decomposition, and remnants of coffin wood suggest that most individuals were buried in a coffin or a shroud. overall preservation of skeletal remains, including infants, was good. the fenyéd cemetery was used repeatedly for several hundred years, primarily during the 11th and 12th centuries. salvage excavations were conducted in 2013 due to erosion that exposed the medieval cemetery and a total of 54 burials were removed (figure 3) (nyárádi, 2013). historical information about the medieval period in transylvania can be hard to find. much of the research about the area is not published in english and does not show up in a standard literature search. additionally, the history of the area is highly contentious in terms of which peoples invaded, owned, and occupied the landscape, as such sources can be heavily biased toward a singular perspective with conflicting information between sides (lendvai, 2004). archaeological evidence has been used as a more reliable indicator of the area’s history (ţiplic 2006). however, even this method is complicated due to outside influences directing the interpretation of sites as a part of a pre-1990 romanian research agenda (cosma & gudea, 2002 cited in ţiplic, 2006). archaeological and historical evidence demonstrates that starting in the 9th century the carpathian basin was an area of extensive biological and figure 1. tri-part map successively focusing on the location of the two cemeteries. map modified from molnár et al. (2015). 81 dental anthropology 2019 │ volume 32 │ issue 02 figure 2. burial plan map of papdomb site with 2014 and 2015 trenches outlined. figure 3. burial plan map of fenyéd site burials. 82 dental anthropology 2019 │ volume 32 │ issue 02 cultural movement from various groups including slavs, croatians, bulgarians, avars, franks, bijelobrdo and the first hungarians (lendvai, 2004; ţiplic, 2006). over the subsequent centuries, populations increased and decreased as a result of political and religious influences, especially from the tatar invasion of the early 13th century. the medieval population size for transylvania as a region has been estimated around 250,000 people with 100 -200 people in an average-sized village. mountainous villages, such as the ones in our case study, may have been smaller with difficult to estimate population sizes (ţiplic, 2006). the effects of large-scale social changes on small villages in transylvania are unknown. this information could be gleaned from cemetery data (ţiplic, 2006), but there has been limited published skeletal research on sites from the carpathian basin. although the bijelo-brdo culture predates the two sites discussed herein, bijelo-brdo cultural elements are present in transylvania and associated with early hungarian sites (10th-11th century). vodanovic and colleagues (2005) report on frequency and location of tooth loss and dental carious lesions from the bijelo-brdo archaeological site near osijek, croatia. they found that carious dental lesions and antemortem tooth loss increased with age. antemortem tooth loss was 11.9% among older individuals and 6.7% for all individuals examined. they also found that 46.9% of individuals had at least one carious lesion with 1.8% of younger individuals having at least one carious lesion and 14% of older individuals having at least one carious lesion. causes for the pattern of dental modification observed were vaguely attributed to diet and lifespan but no direct evidence for antemortem tooth loss or carious dental lesions was provided. in reference to food, peschel and colleagues (2017) examined the diet of 12th to 19th century transylvanians excavated from the bögöz reformed church in mugeni (hungarian: bögöz), romania. they found that people were consuming animals fed from native grasses (pigs, sheep, and cows) as well as broomcorn or foxtail millet. they also reported that individuals from the earlier centuries ate less meat and fish. it is unclear to what degree the transylvanian villagers participated in available dental or other medical treatments during the medieval period. westernization in the székelyföld was visible as early as the 12th century as seen through the presence of a distinct style of hairpin found in association with burials at multiple cemeteries. this finding suggests that mountainous communities might not have been as isolated as assumed (nyárádi & gáll, 2015; ţiplic, 2006). in terms of dental care and status, members of the noble family from the area were interred at the papdomb site and do not show any direct evidence of dental treatment. nor do their teeth appear to have less pathological dental modification than others in the papdomb cemetery as evidenced by the presence of periapical lesions, carious lesions, and antemortem tooth loss including one edentulous individual. to further investigate how the oral condition of the two transylvanian cemetery assemblages compared to other medieval sites, we chose to place the two sites within the broader context of the medieval period in europe. in doing so, we came across the research challenges described in this paper. methods and materials one of the goals of this paper is to report on pathological conditions of the oral cavity among medieval transylvanian székely communities as a case study to apply the vocabulary and definitions discussed by pilloud and fancher (2019) and to demonstrate the challenges of comparison between sites. skeletal assemblages from two cemeteries located 18.5km apart in harghita county, romania were analyzed. all the burials excavated between 2014 and 2015 have been analyzed and comprise the sample of this study. these graves are from trenches within the walls of the church; within the churchyard, and outside the yard wall (see figure 2) providing a sample of individuals across the site. a total of 218 burials were removed during the two seasons of excavation (nyárádi, 2014; zejdlik, 2015). all dental elements were sorted and identified by dental arcade, tooth type, and side. buikstra and ubleker (1994) and the arizona state museum systems were utilized to document dental carious lesions, periodontal recession, antemortem tooth loss, and periapical lesions. antemortem tooth loss and periapical lesions were not always scorable due to poor preservation of maxillary and mandibular bone. to acquire data from comparable medieval sites and to test the utility of a standardized language and definitions as called for by pilloud and fancher (2019), a literature review was conducted to synthesize data related to conditions of the oral cavity from medieval sites across europe. müeller and hussein’s 2017 meta-analysis of dental conditions was used as a model as it provided an extensive overview of the literature reporting on ‘dental health’ from sites between 3,000 bc and the 20th century. we modified their table by extracting only 83 dental anthropology 2019 │ volume 32 │ issue 02 adults from medieval sites and by removing data on postmortem tooth loss, periodontal disease, and linear enamel hypoplasia. the choice to focus on adults was made to simplify the table; adults were more frequently examined than non-adults. adults were considered individuals aged 16 years and older. post-mortem tooth loss was removed from our analysis because it did not provide useful information regarding the condition of the oral cavity. periodontal disease was removed because only two of the 21 references reviewed reported on it. the resulting table (table 1) consists of 21 references reporting on conditions of the oral cavity from medieval peoples across europe. the 21 references include the two case study cemeteries discussed below. it should be noted that some references report on multiple sites. when possible, the site demographics were broken into male and female. each dental condition was reported per total available teeth. without a set glossary of terms and definitions, one cannot be confident what is being compared. pilloud and fancher (2019) have provided recommendations on etiology, skeletal representation, and caution when examining various dental diseases or conditions. in most of the literature cited in table 1, the authors did not describe etiologies. instead, emphasis was placed on the physical evidence being observed and the criteria used to assess it. however, in a few cases, such as dewitte and bekvalac (2010) and lopez et al. (2012) a clear and descriptive presentation of conditions and potential etiologies of the oral cavity are presented. a summary of pilloud and fancher’s (2019) recommendations specifically related to the conditions identified in this paper and reduced to application in observation is provided below: antemortem tooth loss: assessment of this condition should be used cautiously because it has many causes. investigators should preference a large gap in the dental arcade with evidence of reactive bone. they should also be aware of potential dental agenesis and impaction. if uncertain, antemortem tooth loss should not be recorded. carious dental lesions: it is important to differentiate between carious lesions as the physical, dental hard tissue destruction of tooth enamel and, dental caries as the disease process of bacterial fermentation of consumed carbohydrates. the two terms should be used separately. periapical lesions: this is a general term to describe a disturbance of the skeletal tissue around the apex of the tooth that may be related to a granuloma, cyst, or an abscess. the general term of ‘periapical lesion’ is preferred as the specific etiology can be difficult to diagnose without a soft tissue biopsy or a definitive patient history. results a review of the 21 references in table 1 revealed a range of definitions and etiologies associated with the conditions described. diagnostic criteria for antemortem tooth loss was reported in a range of ways. in some cases, the criteria to define antemortem tooth loss was not defined (e.g., lingström & borrman, 1999; slaus et al., 1997; srejić, 2001). in the most simplistic descriptions, it was differentiated from postmortem tooth loss in which there was evidence of an alveolar socket (e.g., caglar et al., 2007; esclassan et al., 2009; vodanović, 2005). others described antemortem tooth loss as evidenced by alveolar resorption or remodeling (e.g., chazel et al., 2005; lopez et al., 2012; meinl et al., 2010; novak, 2015; slaus et al., 2010; stránská, 2015). studies did not consider agenesis or impaction as a potential explanation for a lack of tooth presence. carious dental lesion criteria were also described in numerous ways. most authors used the term caries and did not distinguish between the process and the physical manifestation. the majority of the studies identified carious lesions as ‘caries’ and diagnosed them based on an enamel defect, specifically a pit that could be probed, and made the point to note that discoloration or a sticky lesion was not considered a carious dental lesion (e.g., belcastro et al., 2007; meinl et al., 2010; novak, 2015; stránská, 2015). some authors also used radiographic imaging in addition to macroscopic observation to identify carious lesions (e.g., chazel et al., 2005). most papers did not record periapical lesions. those that did referred to them as abscesses. diagnostic criteria in the papers described the presence of a perforating fistula as necessary for a diagnosis (e.g., belcastro et al., 2007; šlaus et al., 2010). only novak (2015) included the description of a sinus present in the alveolus at the apex of the tooth in addition to a perforating fistula as a diagnostic criterion. several challenges were identified in the attempt to establish a bioarchaeological context useful for comparison to the transylvanian székely case studies, namely the lack of standardization, 84 dental anthropology 2019 │ volume 32 │ issue 02 location/ time period individuals n (male/female/ indeterminate) analyzed teeth n total teeth/ n alveolar presence antemortem tooth loss n (%) carious dental lesions per tooth n (%male/ % female) periapical lesions per tooth n (%male/ % female reference ireland (rural) 400 -1000 ad 167(85/82/-) 3233 nd (9.7%) 98(2.5%/3.6%) 85 2.3% novak 2015 italy (rural), 700 ad 88 (45/40/3) 1754/nd nd (14%) 263 (15%/ 15%) 4.5% belcastro et al. 2007 austria (urban), 700–800 ad 136 (64/72/-) 2215/3649 869 (24%) 331 (15%) nd meinl et al. 2010 czech republic (rural) 8001100ad 241 (-/-/-) 1006/1011 0 6 (0.06%) nd stránská et al. 2015 czech republic (urban) 8001100ad 487 (-/-/-) 1538/2699 0 18 (0.012%) nd stránská et al. 2015 croatia (rural) 700-1100 ad 151(59/38/-) 2707/nd 21.7% 318(11.1%/12.6%) 196 5.1% šlaus et al. 2010 croatia (urban) ad 11001400 107(63/44/-) 643/1378 nddata combined with abscesses 62 (11%/7.6%) nddata combined with antemortem tooth loss novak et al. 2012 croatia (rural), 10 –11th century 81 (-/-/-) 923/ 1414 99/7% all 92/ 10% nd vodanović et al. 2005 france (urban), 11 –15th 107 (-/-/-) 1183/3424 342 (10%) 107 (9%) nd chazel et al. 2005 france (rural), 12 –14th 58 (29/29/-) 1395/1822 121 (7%) 250 (22%/ 14%) nd esclassan et al. 2009 scotland (rural), 1240–1440 561 (-/-/-) 9991/nd 7% all 709/ 7% nd watt et al. 1997 papdomb, romania (rural) 14th -15th 60 (34/21/5) 1074 /nd nd 12.4% 16 (1.4%) current study fenyéd-bradesti, romania (rural) 11 – 12th 32 (-/-/-) 569/nd nd 24.44% 1 (0.2%) blevens and adams 2017 england (urban), ad 1350-1538 190 (-/-/-) nd nd 484 (premolars and molars only) 27.3% nd dewitte & bekvalac 2010 turkey (urban,) 13th 52(-/-/-) 261/nd 51 (6.9%) 8 (15.38%) nd caglar et al. 2007 spain (rural), 15th 240 (123/117/-) 1015/1254 239 (19%) 48 (5%/ 4%) nd lopez et al. 2012 scotland (urban), 13–16th 52 (-/-/-) 984/1246 60/ 4% all ages 54/ 5% nd kerr et al. 1988 serbia (rural), 14– 16th 369 (-/-/-) 1680/2874 299 (10%) 149 (9%) 24 (1.4%) srejic 2001 finland (urban, poor people), 15– 16th 294 (-/-/-) 4581/ 5803 deciduous 600/600 622/11% all ages 731/16% nd varrela 1991 scotland (urban), medieval 74 (-/-/-) 1614/ 1958 pre 255/ 279 156/8% all ages 134/8% 5/7% nd kerr et al. 1990 sweden (urban), 1621–1640 63 (-/-/-) 936/1997 pre 13/48 55/3% all ages 106/11% nd lingström and borrman 1999 croatia (rural), 14 –17th 68 (35/33/-) 765/nd nd 72 (9%) nd šlaus et al. 1997 france (urban), 16 –17th 109 (-/-/-) 1267/3488 519 (15%) 236 (19%) nd chazel et al. 2005 table 1. summary data on conditions of the oral cavity from medieval archaeological sites *nd= no data or not specified 85 dental anthropology 2019 │ volume 32 │ issue 02 which made overall construction of table 1 complicated. there were various forms of missing data and different reporting styles especially in terms of demographics. additionally, the lack of standardization in description of conditions of the oral cavity suggests that while there was a general understanding of processes and analytical methods, there were certainly areas of concern regarding recorded data. the data from table 1 was distilled into descriptive statistics per condition. the numbers provided by each reference were broken down into the minimum percentage of the condition expressed, the maximum, and the mean. not all references investigated all of the conditions reported in table 1. the n column provides the number of references out of 21 that reported the condition. the results of the transylvanian analysis were added to the bottom of the table to highlight how the transylvanian cases fit into the general data on the medieval oral condition. of the 21 references reviewed in table 1, 18 reported on antemortem tooth loss. antemortem tooth loss occurred at variables rates across medieval sites with 0% reported for sites in the czech republic (stránská et al., 2015) and 24% reported for a site in austria (meinl et al., 2010). the average number of total teeth lost antemortem across the sites recoded in table 1 was 10.4%. antemortem tooth loss was not recorded for the papdomb or fenyéd individuals for taphonomic and preservation reasons information regarding carious dental lesions from the two transylvanian sites was examined against the descriptive statistics provided in table 2. all of the 21 references reviewed in table 1 reported on carious lesion prevalence. like antemortem tooth loss, dental carious lesions were reported at variables rates across medieval sites with 0.6% reported for sites in the czech republic (stránská et al., 2015) and 27.3% reported for a st. mary graces cemetery site in england (dewitte & bekvalac, 2010). the average total teeth with carious lesions across the sites recoded in table 1 was 10.3%. interestingly, the numbers for antemortem tooth loss and carious dental lesions across the sites are very similar. also in both cases, the sites from the czech republic have the lowest numbers. when the two transylvanian sites were compared to descriptive statistics in table 2, the papdomb site (12.4%) was just above the overall mean (10.3). however, the fenyéd site (24.4%) was high. it was the second highest reported after the st. mary graces cemetery (27.3%). both transylvanian sites are higher than the bijelo-brdo culture site (7%) to which they are most culturally similar. reporting of periapical lesions was limited. of the 21 references in table 1 only 6, including the two case studies, provided data. the lowest reported prevalence was the fenyéd site case study (0.2%) and the highest (5.1%) reported was an aggregation of three, early medieval villages in croatia (šlaus et al. 2010). the papdomb site had a frequency of 1.4%, which was the second lowest rate. discussion the fenyéd site had the second highest frequency of carious dental lesions among all 21 references reviewed and the lowest frequency of periapical lesions. the papdomb site was slightly above average for frequency of carious lesions and had the second lowest frequency of periapical lesions. the two cemeteries were 18km away from each other and were used at the same time. both were in rural transylvania in a hilly area of the carpathian basin. they were, and remain, small villages with similar people, similar occupations, and similar access to resources. the two skeletal populations demonstrate very limited evidence of trauma or pathological indicators minus the expected occurrences of osteoarthritis and other common degenerative modifications in older individuals. all things considered, it had been assumed that the two sites would have had similar conditions of the oral cavity. it is possible that sample size, 32 adults from fenyéd versus 60 adults from papdomb, could have impacted the results. regardless, the difference suggests that other factors were present and point in a direction of further investigation. conclusions health is a vague term that encompasses physical, emotional, mental, and social factors. to adequately study health requires patient histories and a better understanding of etiological factors. it is difficult to interpret in the bioarchaeological record. it is limited by the inherent attributes of archaeological skeletal assemblages. however, as bioarchaeologists we are tasked with finding ways to overcome those challenges in investigation and interpretation to best represent the people we are speaking about. situating interpretation within the social and cultural context of a specific time and place is important even if it is indirect and acquired through less utilized means of knowing, such as images and folklore. this has become apparent in our research among the székely of transylvania whose 86 dental anthropology 2019 │ volume 32 │ issue 02 own origin story is unknown and has written itself out of lore and legend (lemdvai, 2004). next, applying bioarchaeological data at various scales provided different perspectives on the variability across time and place even though it all fell under the classification of ‘medieval.’ specifically, this study demonstrated that the oral cavity was variable across medieval europe even in cases with similar contexts such as transitions from late antiquity to the early medieval period, sites in croatia and romania with similar cultural periods, or two rural, székely, transylvanian villages. finally, further complicating the situation was a lack of standardization in descriptions and reporting, which underscores the call of pilloud and fancher (2019) to standardize terminology and further understand the etiology of processes that affect the oral cavity; hopefully, leading to improvements in data reporting. we will never know what ancient individuals experienced or perceived in terms of their dental health but we can be more responsible in the way we discuss it. references anderson, t. (2004). dental treatment in medieval england. british dental journal, 197(7), 418-425. belcastro, g., rastelli, e., mariotti, v., consiglio, c., facchini, f., & bonfiglioli, b. (2007). continuity or discontinuity of the life‐style in central italy during the roman imperial age‐early middle ages transition: diet, health, and behavior. american journal of physical anthropology, 132 (3):381-394. bethard, j.d, osterholtz a.j., nyárádi z, & gonciar, a. (2019). marginalized motherhood: infant burial in seventeenth-century transylvania. in c.i. tica & d.l. martin (eds.), bioarchaeology of frontiers and borderlands (pp. 252-272). gainesville, fl: university press of florida. betsinger, t.k., & dewitte, s. 2017. trends in mortality and biological stress in a medieval polish urban population. international journal of paleopathology, 1, :24-36. blevins, b., & adams, d. (2017). dental stress markers of a medieval transylvanian population. paper presented at the 86th annual meeting of the american association of physical anthropologists, new orleans, la. bifulco, m., amato, m., gangemo, g., marasco, m., caggiano, m., amato, a., & pisanti, s. (2016). dental care and dentistry practice in the medieval medical school of salerno. british dental journal, 221(2), 1-3. buikstra, j.e., & ubelaker, d.h. (1994). standards for data collection from human skeletal remains: proceedings of a seminar at the field museum of natural history, organized by jonathan haas: arkansas archeological survey. caglar, e., kuscu, o., sandalli, n., & ari, i. (2007). prevalence of dental caries and tooth wear in a byzantine population (13th cad) from northwest turkey. archives of oral biology, 52(12), 1136-1145. chazel, j-c., valcarcel, j., tramini, p., pelissier, b., & mafart, b. (2005). coronal and apical lesions, environmental factors: study in a modern and an archeological population. clinical oral investigations, 9(3), 197-202. clarke, n.g., & hirsch, r.s. (1991). physiological, pulpal, and periodontal factors influencing alveolar bone. in m.a. kelly & c.s. larsen (eds.), advances in dental anthropology (pp. 241 -266). new york: wiley-liss. dewitte, s.n., & bekvalac, j. (2010). oral health and frailty in the medieval english cemetery of st mary graces. american journal of physical anthropology, 142(3), 341-354. esclassan, r., grimoud, a., ruas, m., donat, r., sevin, a., astie, f., lucas, s., & crubezy, e. (2009). dental caries, tooth wear and diet in an adult medieval (12th–14th century) population from mediterranean france. archives of oral biology, 54(3), 287-297. irfan, u.m., dawson, d.v., & bissada, n.f. (2001). epidemiology of periodontal disease: a review and clinical perspectives. journal of international academy of periodontology, 3(1), 14-21. jouanna, j. (2012). the legacy of the hippocratic treatise the nature of man: the theory of the four humours. in p. van der eijk (ed.), greek medicine from hippocrates to galen (pp. 335-359). antemortem tooth loss (n= 18) carious dental lesions (n=21) periapical lesions (n=6) min 0% 0.6% 0.2% max 24% 27.3% 5.1% average 10.4% 10.3% 3.3% papdomb nd 12.4% 1.4% fenyéd nd 24.44% 0.2% table 2: descriptive statistics of the data reported in table 1 with the transylvanian sites highlighted for comparison 87 dental anthropology 2019 │ volume 32 │ issue 02 leiden, neatherlands:brill. kerr, n. (1990). the prevalence and pattern of distribution of root caries in a scottish medieval population. journal of dental research, 69(3), 857 -860. kerr, n., bruce, m., & cross, j. 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(2010). caries frequency and distribution in an early medieval avar population from austria. oral diseases, 16 (1), 108-116. molnár, z m. (2001). a concise history of hungary. cambridge: cambridge unviersity press. molnár, z., gellény, k., margóczi, k., & biró, m. (2015). landscape ethnoecological knowledge base and management of ecosystem services in a székely-hungarian pre-capitalistic village system (transylvania, romania). journal of ethnobiology and ethnomedicine, 11(3), 1-22. http:// www.ethnobiomed.com/content/11/1/3 müller, a., & hussein, k. (2017). meta-analysis of teeth from european populations before and after the 18th century reveals a shift towards increased prevalence of caries and tooth loss. archives of oral biology, 73, 7-15. novak, m. (2015). dental health and diet in early medieval ireland. archives of oral biology, 60(9), 1299-1309. novak, m., martinčić, o., strinović, d., & šlaus, m. (2012). skeletal and dental indicators of health in the late mediaeval (12–15th century) population from nin, southern croatia. homojournal of comparative human biology, 63(6), 435 -450. nyárádi, z. (2013). a fenyédi csonkatemplom régészeti feltárása. paper presented at the haáz rezső museum. székelyudvarhely, romania. nyárádi, z. (2015). report de cercetare arheologică preventivă. văleni-„papdomb” biserica medieval. campania 2015. muzeu haás rezső museum. nyárádi, z., & gáll, e. (2016). the ‘westernization’ of the transylvanian basin: migration and/or acculturation?: wearing hairpins in the 12th century transylvanian basin. vjesnik arheološkog muzeja u zagrebu, 48(1), 85-120. pelling, m. (1998). the common lot: sickness, medical occupations and the urban poor in early modern england. london: routledge. peschel, e. m., dunn, t. e., bethard, j. d., nyaradi, z., gonciar, a., katzenberg, m. a., & ambrose, s. h. (2017, april). reconstructing szekely subsistence: stable isotope evidence for medieval diet in eastern transylvania. american journal of physical anthropology, 162, 314. pilloud, m.a., & fancher, j.p. (2019). outlining a definition of oral health within the study of human skeletal remains. dental anthropology, 32(2), 3-11. reitsema, l.r., & mcilvaine, b.a. (2014). reconciling “stress” and “health” in physical anthropology: what can bioarchaeologists learn from the other subdisciplines?. american journal of physical anthropology, 155, 181-185. šlaus, m. (2008). osteological and dental markers of health in the transition from the late antique to the early medieval period in croatia. american journal of physical anthropology, 136 (4), 455-469. šlaus, m., bedić, ž., šikanjić, p.r., vodanović, m., & kunić, a.d. (2010). dental health at the transition from the late antique to the early medieval period on croatia's eastern adriatic coast. international journal of osteoarchaeology, 21,(5), 577-590. šlaus, m., pećina-hrnčević, a., & jakovljević, g. (1997). dental disease in the late medieval population from nova rača, croatia. collegium antropologicum, 21(2), 561-572. srejić, m.d. (2001). dental paleopathology in a serbian medieval population. anthropologischer anzeiger, 59(2), 113-122. stránská, p., velemínský, p., & poláček, l. (2015). the prevalence and distribution of dental caries in four early medieval non-adult populations of different socioeconomic status from http://www.ethnobiomed.com/content/11/1/3 http://www.ethnobiomed.com/content/11/1/3 88 dental anthropology 2019 │ volume 32 │ issue 02 central europe. archives of oral biology, 60(1), 62-76. ţiplic, i. m. (2006). transylvania in the early middle ages: (7th-13th c.). arbeitskreis für siebenbürgische landeskunde (working group for transylvanian archaeology). varrela, t.m. (1991). prevalence and distribution of dental caries in a late medieval population in finland. archives of oral biology, 36(8), 553-559. vodanović, m., hrvoje, b., mario, š., & željko, d. (2005). the frequency and distribution of caries in the mediaeval population of bijelo brdo in croatia (10th–11th century). archives of oral biology, 50(7), 669-680. watt, m.e., lunt, d.a., & gilmour, w.h. (1997). caries prevalence in the permanent dentition of a mediaeval population from the south-west of scotland. archives of oral biology, 42(9), 601620. world health organizaton. (1948, april 7). preamble to the constitution of who as adopted by the international health conference, new york, 19 june 22 july 1946; signed on 22 july 1946 by the representatives of 61 states. official records of who 2:100. https://www.who.int/ about/who-we-are/frequently-askedquestions zejdlik, k. (2015). archaeotek summer field season 2015: medieval funerary excavations at papdomb, patakfalva. on file with archaeotek canada, llc. padgett 2010.4 25 dental fusion of the primary dentition is a rare congenital anomaly. examples in the literature of bioarchaeology are exceedingly scarce. skeletal remains of an infant from the law’s site (1ms100), in marshall county, alabama, presents a clear case of triple fusion of the primary dentition. this is a highly unusual condition, and thus a significant find for the fields of dental anthropology and bioarchaeology. literature review examples of dental fusion in the anthropological literature are uncommon, and texts on dental anthropology, developmental osteology, and paleopathology give the topic little or no attention (aufderheide and rodríguezmartín, 1998; hillson, 1996; ortner, 2003; scheuer and black, 2000). two fused deciduous mandibular incisors are shown in figure 1.1 of the anthropology of modern teeth (scott and turner, 1997: 5), but neither the defect nor the provenance of the specimen is discussed in detail. a rare “talon cusp” found on a deciduous lateral incisor was the primary topic of a case report of a juvenile skeleton excavated in england, though the report states that “the affected incisor also shows abnormal widening, probably representing a double tooth”, and mentions the presence of a supernumerary permanent incisor (mays, 2004:206). it is unclear if this “double tooth” is an actual case of dental fusion, or a case of gemination, defined as the unsuccessful or incomplete division of one tooth germ into two (canut brusola, 1988; oliván rosas et al. 2004). some authors agree that distinction between fusion and gemination can sometimes be confusing, and the term “double teeth” should be used when the diagnosis is inconclusive (andlaw and rock, 1999; gonzalez marquez and mendez-nuñez, 1993; killian and croll, 1990; oliván rosas et al., 2004; uys and morris, 2005). although there is little in anthropological sources concerning the topic of dental fusion, there have been some relevant clinical studies on modern populations, and some patterns have been documented regarding this dental anomaly. these clinical studies agree that fusion in the primary dentition usually affects two teeth triple fusion in the primary dentition from law’s site, alabama (1ms100): a case report brian d. padgett frankfort, ky correspondence to: brian d. padgett, 313 juniper drive, frankfort, ky 40601 e-mail: boneyard90@hotmail.com abstract dental fusion of the primary dentition is a rare congenital anomaly. evidence in the literature of bioarchaeology is scarce. burial ms100-14 was recovered from law’s site on pine island, in marshall county, alabama. analysis of the remains found that ms100-14 presented a clear case of triple fusion of primary dentition in the maxilla. this appears to be the first case of triple fusion reported from among prehistoric native american remains in the southeastern united states. dental anthropology 2010;23(1):25-27. unilaterally in the mandibular arch, and most often in the anterior region; that is, either two incisors, an incisor and a canine, or a supernumerary tooth fused with an incisor (barberia et al., 2001; cheng et al., 2003; favalli et al., 1998; modrizuki et al., 1999; oliván rosas et al., 2004; yonezu et al., 1997). studies among european, (asian) indian, and turkish populations reveal a prevalence of less than 1% for double fusion in primary dentition (aquiló et al., 1999; barberia leache and boj quesada, 2001; boj quesada 1990; bruce et al., 1994; erdem et al., 2001; reddy and munshi, 1999). north american populations have a prevalence ranging from 0.14 to 3% (hagman, 1988). a study in shenyang city, china, reported 1.52% prevalence among children there (cheng et al., 1999). the prevalence appears to be highest in japan, where 4.1 to 5% of children studied presented this anomalous feature, and unlike other populations, there was a tendency regarding sex, as a significantly higher proportion of boys displayed congenital dental fusion (modrizuki et al., 1999; yonezu et al., 1997). as rare as double fusion appears to be, it is not surprising that triple fusion of primary dentition is even less common. in the study of indian children (n = 4,205), there was no case of triple fusion (reddy and munshi, 1999), though a separate team from india reports the case of a child with triple fusion involving two ipsilateral incisors and a supernumerary tooth (prabhakar et al., 2004). among chinese children studied (n = 4,286), only one case of triple fusion was found, involving two ipsilateral incisors and the adjoining canine (cheng et al., 1999). the prevalence of “triplication of primary teeth” among turkish children was stated as 0.02% (erdem et al., 2001). problems associated with the congenital fusion of primary dentition may include an increased susceptibility to caries in the fused teeth (reddy and munshi, 1999). 26 there is also an association between fusion of primary dentition and agenesis of the corresponding permanent teeth; with regard to this condition, various authors cite percentages of incidence ranging from 20 to 75%, the occurrence of which may depend on which teeth are fused (aquiló et al., 1999; barberia leache and boj quesada, 2001; boj quesada 1990; canut brusola 1988; oliván rosas et al., 2004; ostos garrido and peñalva sanchez, 1996; hagman, 1988; reddy and munshi, 1999). materials and methods a standard osteological analysis was performed on the skeletal remains recovered from law’s site (1ms100). the law’s site was a village on the southern end of pine island in marshall county, alabama. the site was excavated in 1938 by the works project administration (wpa) under the direction of carl f. miller (webb and wilder, 1951). shortly thereafter, pine island was inundated when construction of guntersville dam was completed and the low-lying guntersville basin flooded to become guntersville lake. the site had seen native american occupation since the archaic period (about 8,000-1,000 b.c.) (walthall, 1980); though many of the burials have been convincingly attributed to the post-contact period, between 1540 and about 1715 (fleming, 1976; padgett, 2007; webb and wilder, 1951). it is believed that the native occupants of this latter period were the historically known koasati, or coushatta, tribe (padgett, 2007; swanton, 1985, 1989), though there is some dispute on this issue (hudson, 1997). case report burial ms100-14 was an infant of indeterminate sex, aged about 9 months based on dental eruption. no indications of pathological infection or physical trauma were found among the remains. burial ms100-14 exhibited fused dentition, appearing as a block of three teeth fused side by side in their standard position. the fused set consists of the deciduous left maxillary central incisor, lateral incisor, and canine (fig. 1). the central incisor and canine appear to be of normal dimensions, while the lateral incisor is reduced in mesiodistal width, and appears to be a conically-shaped “peg tooth.” discussion the three teeth are fused at both the enamel and the dentin, though all three can be recognized as distinct from the others (fig. 1). furthermore, it is apparent that although the pulp cavities of the three teeth are continuous with each other, each tooth was maintained by its own root canal. these observations support the assertion that this is a true case of dental fusion, rather than gemination of a single tooth (oliván rosas et al., 2004; uys and morris, 2005). some studies have found a predilection for one sex or the other regarding fused teeth or peg teeth (wu and feng 2005; yonezu et al., 1997); however, no evidence relating to sex can be interpreted from the remains or associated materials of burial ms100-14. conclusion the expression of triple fusion in ms100-14 as a dental anomaly is unusual in that it occurred among the maxillary dentition, as other researchers have found that when dental fusion occurs it is predominantly in the mandibular arch (cheng et al., 2003; yonezu et al., 1997). the peg-shaped tooth, while an anomalous feature, is typical in the respect that it is a lateral incisor (wu and feng, 2005). burial ms100-14 represents a rare case in physical anthropology of triple fusion of primary dentition found in an archaeological context. furthermore, the case fig. 1. fused teeth of burial ms100-14. (left) labial view with the left primary central incisor (i1) to the left of the photograph, a conical lateral incisor (i2) in the center, and the canine (c) to the right. (center) lingual view of the fused teeth, with c to the left and i1 to the right. (right) alveolar (apical) view of the formative roots with c to the left and i1 to the right of the photograph. b.d. padgett 27primary tooth triple fusion of ms100-14 is significant as it appears to be the first case of triple fusion reported from among prehistoric native american remains in the southeastern united states. literature cited andlaw rj, rock wp. 1999. manual de odontopediatría. mexico city: mcgraw-hill interamericana. aquiló l, gandia jl, cibrian r, catala m. 1999. primary double teeth: a retrospective clinical study of their morphological characteristics and associated anomalies. int j pediatric dent 9:175-183. aufderheide ac, rodríguez-martín c. 1998. the cambridge encyclopedia of human paleopathology. cambridge: cambridge university press. barberia leache e, boj quesada jr. 2001. odontopediatría, 2nd ed. barcelona: masson. boj quesada jr. 1990. dientes dobles. archivos odontología 6:321-325. bruce c, manning-cox g, stanback fryer c, banks k, gilliam m. 1994. a radiographic survey of dental anomalies in black pediatric patients. nda j 45:6-13. canut brusola ja. 1988 ortodoncia clínica. barcelona: salvat. cheng rb, chen x, liu sj, pan l, wu xg. 2003. [an epidemiological survey on fusion of deciduous teeth of 4286 kindergarten children in shenyang city.] shanghai kou qiang yi xue. 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[a survey of number and morphology anomalies in permanent teeth of 6,453 youths between 17 to 21 years old.] zhonghua kou qiang yi xue za zhi [chinese j stomatology] 40:489490. translated from chinese. yonezu t, hayashi y, sasaki j, machida y. 1997. prevalence of congenital dental anomalies of the deciduous dentition in japanese children. bull tokyo dental college 38:27-32. 3 dental anthropology 2023 │ volume 36│ issue 02 a histological study of enamel developmental defects in a chacma baboon (papio ursinus) incisor jamal k. salaymeh 1* , jimmy erkens 1 , esme beamish 2 , w. scott mcgraw 1 , debbie guatelli-steinberg 1 , kate mcgrath 1,3,4 1 department of anthropology, the ohio state university 2institute for communities and wildlife in africa (icwild), university of cape town 3department of anthropology, suny oneonta 4center for the advanced study of human paleobiology, department of anthropology, the george washington university some chacma baboons inhabiting south africa’s cape peninsula live in close proximity to human dwellings and tourist attractions (hoffman and o’riain, 2011). human-modified environments have been shown to offer baboons the opportunity to find high-calorie foods in the form of crops or food waste, which is linked to more rest time and improved body condition (strum, 2010). each square kilometer of human-modified habitat on the cape peninsula can support almost five times the baboon population compared to a square kilometer of natural habitat (hoffman and o'riain, 2012). however, human-modified environments can expose baboons to more frequent, and oftenaggressive, interactions with humans (kansky and gaynor, 2000) (figure 1). baboons that persistently exhibit behavior that threatens the safety and welfare of residents in the cape peninsula may be euthanized (beamish and o’riain, 2014), sometimes leading to the extirpation of entire baboon troops (skead, 1980). both physiological and behavioral responses to stress have been observed in chacma baboons residing in table mountain national park; adult baboons that spend more time in anthropogenic habitats have higher levels of glucocorticoid hormones, exhibit more aggressive behavior, and spend less time socializing (chowdhury et al., 2020). physiological stress during early development, such as bodily trauma, febrile illness, or malnutrition, is associated with disruptions in the normal enamel abstract physiological stress disrupts normal tooth growth creating grooves on the enamel surface (i.e., linear enamel hypoplasia or leh). hypoplastic defects often, but not always, co-occur with internal accentuated lines (al). monkeys reportedly exhibit fewer enamel defects than hominoids as their presumably faster-growing teeth produce shallower leh defects that are harder to macroscopically identify. in this case study of a chacma baboon (papio ursinus) incisor, we assessed whether al are matched by leh defects; how enamel extension rates (eer) and striae angles relate to the surface distribution of leh defects; and whether striae angles are acute and eers fast compared to hominoid anterior teeth. normal wear to this specimen resulted in enamel loss (first two deciles) and surface abrasion, mainly near the cusp. we found a higher occurrence of al (n = 48) compared to leh defects (n = 10), which co-occurred in all instances of leh. the spatial distribution of al is more consistent, ranging from 310/decile, while leh defects occur mainly in the midcrown and cervical regions. this incisor exhibits faster eers (mean = 23.6 µm/day) and acuter striae angles (11-16°) compared to hominoids, likely creating shallower leh defects and contributing to the discrepancy between al and leh defects. *correspondence to: jamal k. salaymeh the ohio state university email: salaymeh.1@osu.edu keywords: dental histology, linear enamel hypoplasia, accentuated lines 4 dental anthropology 2023 │ volume 36│ issue 02 secretion activity (amelogenesis) of ameloblasts (goodman and rose, 1990; guatelli-steinberg et al., 2012; hillson and bond, 1997; nanci, 2018). the present study focuses on two types of disruptions in enamel secretion: linear enamel hypoplasia and accentuated lines. linear enamel hypoplasia (leh) manifests as horizontal grooves or lines that appears on the enamel surface (goodman and rose, 1990; guatelli -steinberg et al., 2012) (figure 2). leh defects often, but not always, co-occur with accentuated lines (al) visible in the enamel cross-section (condon and rose, 1992; witzel et al., 2008). the co -occurrence of the two defect types is expected, as it is thought that leh and al are external and internal manifestations of the same disruption in normal tooth growth (goodman and rose, 1990). however, a three threshold model for interpreting disturbances in enamel secretion at the cellular level has been set forth (kierdorf et al., 2000; kierdorf et al., 2004; witzel et al., 2006; witzel et al., 2008) and proposes an explanation for the variable cooccurrence of the two defect types: when the lowest threshold is surpassed, the minor disruption in growth can result in an leh defect without the formation of a co-occurring accentuated line. they also considered the timing of the disruption, arguing that accentuated lines are formed when all the involved ameloblasts are impaired, while leh defects manifest when ameloblasts are disrupted during the late stage of secretion. accentuated lines manifest in enamel crosssections as dark, pronounced lines that either fall between, or are coincident with, normal striae of retzius (guatelli-steinberg, 2016). the latter structures form due to regular alterations in mineralization, mineral composition, or changes in the prism or crystalline structure of the enamel (risnes, 1990), and represent a regular enamel growth rhythm, ranging from 2 to 12 days in primates (dumont, 1995; mahoney et al., 2017; mcgrath et al., 2019). it has been suggested that monkeys are less likely to exhibit leh defects than great apes as the angles that their striae of retzius make with the enamel surface are acute, leading to defects that are shallow and difficult to detect (guatellisteinberg et al., 2012; mcgrath et al., 2019). the acute striae angles in monkey teeth may represent fast rates of enamel extension, or the rate at which ameloblasts differentiate along the enamel-dentine junction (shellis, 1998). previous analyses in great figure 1. left: female chacma baboon attempting to access food in a locked waste disposal bin (courtesy of larissa swedell). right: male showing teeth in an act of intimidation (courtesy of human wildlife solutions). 5 dental anthropology 2023 │ volume 36│ issue 02 apes have documented strong relationships between faster enamel extension rates, acute striae angles just below the outer enamel surface (oes), and shallow leh defects (mcgrath et al., 2019). enamel extension rates and associated striae angles change as enamel formation proceeds from cusp to cervix (guatelli-steinberg et al., 2012; mcgrath et al., 2019; shellis, 1998). both human and nonhuman primate anterior teeth exhibit the highest enamel extension rates in the cuspal part of the crown, with reductions by the midcrown region. in humans, extension rates continue to decrease from the midcrown to the cervix. in nonhuman ape canines, extension rates remain constant, or in some cases, and particularly in males, increase toward the cervix (mcgrath et al., 2019), with an associated decrease in the number of identified leh defects in the last deciles (guatelli-steinberg et al., 2012). less is known about the details of how enamel extension rates and striae angles change along the crowns of incisors, and currently no leh defect depths exist for any monkey species. however, it might be expected that monkeys with their faster life histories and relatively smaller body sizes should exhibit even faster enamel extension rates and acuter striae angles compared to hominoids. intrinsic growth variation influences leh defect expression among species, sexes, and tooth types, while extrinsic variables like dental wear and abrasion add additional complications when interpreting imperfectly preserved teeth. primate enamel is generally subject to considerable abrasion pressure that is attributed to the composition of their diet (lucas et al., 2008) and the nature of their masticatory and extra‐masticatory (e.g., using anterior teeth to grasp non-food items) tooth use behaviors (molnar, 2011; stojanowski et al., 2016). incisor enamel is more susceptible to polishing and chipping compared to other tooth types (stojanowski et al., 2016). this abrasion pattern is observed due to the anterior position of incisors in the skull, which provides the animal greater control when manipulating or processing dietary and non-dietary items using teeth (stojanowski et al., 2016; ungar, 1994). figure 2. a: cranium of male chacma baboon b4-03 with the sectioned incisor (uli1) highlighted. b: macrophotograph of the incisor epoxy replica; red arrows mark the approximate locations of leh defects (n = 10). nine leh defects were classified as minor; one defect (fifth leh defect from the top of the image) was classified as moderate. 6 dental anthropology 2023 │ volume 36│ issue 02 this abrasion is exacerbated by the fact that many food items in baboon diets (especially hypogeous foods) are often contaminated with soil, sand, or other particulate matter, accelerating the wear rate of teeth by introducing exogenous grit to the oral cavity (daegling and grine, 1999; galbany et al., 2014). since normal tooth wear occurs mostly near the cusp, cuspal leh defects may erode off the surface and become imperceptible, making them more challenging to identify compared to cervical leh defects. in the present study, a male chacma baboon (papio ursinus) upper left incisor was thin sectioned and analyzed. the correspondence between leh and al defects is evaluated by comparing the association between these defect types on the enamel surface (leh) and in the enamel cross-section (al). here we ask: (1) to what extent do leh and al defects co-occur on this baboon incisor? (2) are rates of enamel extension, and associated striae angles, related to the distribution of leh on the surface of this incisor? (3) are this baboon’s incisor striae angles acute and rates of enamel extension fast in comparison with those of great apes? answers to these questions add to our understanding of the correspondence between al and leh defects, how much of a baboon’s anterior tooth crown is likely to exhibit leh in relation to al, how fast baboon incisors grow, and how striae angles affect the manifestation of leh defects. materials and methods the individual chosen for this analysis (identifier: b4-03) was a large (29.2 kg) male that lived in table mountain national park near cape town and was euthanized for exhibiting aggressive behavior towards locals. this tooth was chosen for this histological study during the data collection phase of a larger study examining the difference in leh prevalence between baboons living inside versus outside national parks. a second tooth (uli1) from a different male chacma baboon (identifier: b2-03) was included in this study to measure midcrown striae of retzius angles at the outer enamel surface. an impression of the first upper left incisor (uli1) (see figure 2) was created using coltene president jet light body silicone impression material. the incisor’s impression allowed for the creation of a high-resolution replica using loctite ea e -60nc epoxy. macrophotographs of the replica were acquired using a digital microscope (leica dms1000) and stitched using adobe photoshop cs6. the replica was examined with the naked eye to identify leh defects on the surface. individual leh defects were assessed both with the naked eye and with the aid of macrophotographs. in this study, even minor perturbations involving the disruption of one or two perikymata growth increments were included in the leh sample, which some authors might instead call “accentuated perikymata” (thylstrup and fejerskov, 1978; kierdorf et al., 2000; temple, 2014; o’hara et al., 2023). a tripartite scheme was used to classify leh defects as minor, moderate, or severe. the qualitative classification of leh was made relative to other defects within the same tooth; comparing a given defect relative to other defects in the same tooth corrects for inter-tooth differences in growth and wear patterns. the position of an leh defect along the length of the enamel was also considered, as seemingly shallow defects near the cusp of a heavily worn tooth are likely to be more severe (i.e., associated with a larger disruption in enamel formation) than their current state suggests. the incisor was extracted by first securing the cranium to a laboratory bench and covering the tooth with padding material to prevent surface damage. the incisor was then pulled away from the cranium using locking flat pincers. after extraction, the incisor was embedded in buehler epoxicure 2 epoxy. using a buehler isomet lowspeed saw, an initial cut was performed along the sagittal plane of the incisor at a speed of 90 revolutions per minute. one side of the halved tooth was then attached to a microscope slide using the same epoxy material. the second cut was performed at the same angular speed and at a distance of 800 µm into the sectioned incisor relative to the surface of the microscope slide. the second cut yielded a thin section of the incisor 800 µm in thickness. after the sectioning process was complete, the specimen was attached to a target holder and ground to a thickness of 150 µm (thickness measurement includes thin section and epoxy adhesive) using progressively finer silicon carbide grinding paper. to minimize fine scratches, 0.3 µm alumina polishing compound was used to polish the slide in preparation for microscopy and imaging. using a brightfield microscope, images of the enamel were acquired at 4x magnification (1 pixel = 1.62 µm). fiji (preibisch et al., 2009) and adobe photoshop cs6 were used to stitch the images, producing a single image of the entire tooth section. the cuspal region is not preserved in this section due to normal wear (figure 3). therefore, the approximate location of the dentine horn was estimated by extending the trajectories of the labial and lingual enamel-dentine junctions until they 7 dental anthropology 2023 │ volume 36│ issue 02 met. the reconstructed enamel-dentine junction length was measured and divided into deciles 1 through 10 (numbered from cusp to cervix) for analysis. decile 1 and approximately half of the length of decile 2 constitute enamel lost to normal wear. enamel extension rates for the preserved deciles (3-10) were calculated by dividing the length of each decile (1/10 of the total length) by the number of days each decile took to form (table 1). days were calculated by counting the number of regular striae of retzius in each decile and multiplying by the periodicity. figure 4 shows the microscopic images of the enamel cross section obtained at 10x and 40x magnification to assess enamel periodicity, which was determined to be 7 days. this periodicity matches the previously reported value for the genus papio (dirks et al., 2002). the number of days it took for deciles 3-10 to form was also calculated by multiplying the number of striae in each decile by the periodicity (see table 1). striae angle measurements were taken within the middle of each decile directly below the outer enamel surface. using adobe photoshop, one arm of the angle tool was placed on the outer enamel surface while the other arm was extended along a single stria of retzius approximately one third into the enamel thickness. midcrown striae angles of another incisor (uli1) from a different male chacma baboon (identifier: b2-03) were also measured at the outer enamel surface (the mean of the two specimens is reported in table 3). accentuated lines (al) appear as relatively dark and pronounced lines that do not follow the normal enamel formation rhythm (guatelli-steinberg, 2016). we attempted to score al with the same level of sensitivity as we scored leh defects; this meant that even minor al were included in this sample. lines were considered accentuated when they appeared out of the normal rhythm (i.e., there was an extra line between normal striae of retzius) and/or when lines, whether falling with the normal rhythm or not, appear darker, thicker, and course more deeply into the enamel thickness compared to nearby striae of retzius. examples of al defects are shown in figure 5. figure 3. overview montage of male chacma baboon b4-03 uli1 thin section (4x magnification). red lines mark the starting locations of deciles on the enamel-dentine junction and continue across the enamel to the points at which the striae of retzius terminate on the outer enamel surface. 8 dental anthropology 2023 │ volume 36│ issue 02 figure 4. left: 10x magnified image of b4-03 uli1 with arrows showing the locations of striae of retzius and rectangle denoting the region imaged at 40x magnification for periodicity assessment. right: 40x magnified image with lines marking striae of retzius and arrows marking daily cross striations. daily cross striations were counted and measured to determine the periodicity of seven days. decile mean striae of retzius angles eer (µm/day) cumulative days (years) leh defects al defects 3 n/a 43.9 49 (0.134) 0 6 4 n/a 43.9 98 (0.268) 0 5 5 10.7° 17.1 224 (0.614) 0 10 6 13.7° 15.4 364 (0.997) 1 7 7 14.0° 16.2 497 (1.362) 1 4 8 13.7° 25.6 581 (1.592) 2 5 9 15.3° 18.1 700 (1.918) 1 3 10 11.0° 9.0 938 (2.570) 5 8 table 1. mean striae of retzius angles, enamel extension rates (µm/day), cumulative days of enamel formation, leh defects, and al defects per decile for b4-03 uli1. 9 dental anthropology 2023 │ volume 36│ issue 02 in order to assess leh and al defect cooccurrence, the distance from the cementumenamel junction to each leh defect was recorded from the macrophotographs. the straight-line tool (adobe photoshop) was then dragged the same distance from the cementum-enamel junction visible in the thin section to the outer enamel surface where a surface groove was identified. results there is a higher occurrence of accentuated lines (n = 48) compared to leh defects (n = 10) in this chacma baboon first upper incisor. leh defects were found to always co-occur with al defects. accentuated line defects are more evenly distributed throughout the enamel, while all leh defects originated only within deciles 6-10 as defined at the enamel-dentine junction. however, due to the nature of crown development and curvature of striae, leh defects are visible across much of the crown surface (see figure 2). the frequency of leh defects increases from cusp to cervix, with no defects originating in deciles 3-5, one defect per decile originating in deciles 6, 7, and 9, two defects originating in decile 8, and five defects originating in decile 10. table 1 (above) lists mean striae of retzius angles for deciles 5 through 10. the most acute mean striae of retzius angles are found in decile 5 (10.7°), while the most obtuse mean angles are found in decile 9 (15.3°). table 1 also lists enamel extension rates (eer) and cumulative enamel formation days. deciles 3 and 4 exhibited the highest eer in this tooth (43.9 µm/day), while decile 10 exhibited the lowest eer (9.0 µm/day). the mean eer across all deciles for b4-03 uli1 is 23.6 µm/ day, and is listed in table 2 in comparison to mean eers of anterior teeth of six other primate taxa derived from other studies. midcrown striae of retzius angles for the main subject of this study, individual b4-03, are 13.7°, while individual b2-03 had more acute midcrown angles at 13.3°. mean midcrown striae angles are listed in table 3 along with comparisons to the mean angles of anterior teeth of five other primate taxa derived from other studies. figure 5. 4x magnified image of b4-03 uli1. red arrows mark the approximate locations of leh defects on the outer enamel surface. dotted red, green, and blue lines mark the approximate locations of al defects in the enamel cross-section. taxon tooth type mean eer (µm/day) papio ursinus uli1 23.6 mandrillus sphinx1 li1 15.5 li2 14.9 g. b. beringei2 lc 12.7 g. g. gorilla2 lc 9.4 p. troglodytes2 lc 8.6 pongo sp.2 lc 8.0 table 2. mean enamel extension rates (eer) in µm/day for individual anterior teeth of six primate taxa. uli1: upper left first incisor. li1: lower first incisor. li2: lower second incisor. lc: lower canine. 1dirks, lemmers, ngoubangoye, herbert, and setchell, 2020. 2mcgrath et al., 2019 10 dental anthropology 2023 │ volume 36│ issue 02 discussion specimen selection this specific incisor (b4-03 uli1) was chosen for this study for three reasons. first, the incisor contained a considerable number of leh defects that are not confined to a small area of the outer enamel. this indicated that the enamel histology was likely to contain a number of al defects that are also distributed throughout the enamel. these defects also varied in severity, allowing for the opportunity to find accentuated lines of varying severity. second, incisors have relatively low eer compared to canines. slow eers (associated with relatively obtuse striae angles) may create leh defects that are deeper and more defined (guatellisteinberg et al., 2012; mcgrath et al., 2019). in male primates, canines tend to have longer crown formation times compared to incisors (ash and nelson, 2003; reed, 1973), allowing for the accrual of more leh defects (guatelli-steinberg and lukacs, 1998). however, this individual’s canines contained a very large number of extremely shallow defects that often merged into indistinct grooves, preventing accurate discrimination of the boundaries of each defect. the third reason we chose an incisor (vs. a canine) for this study was a practical one; our low-speed saw was able to effectively cut the incisor, whereas the great length of the male chacma baboon canines prevented reliable sectioning using the available equipment. tooth wear: important considerations in this study’s main tooth of focus, normal tooth wear resulted in the loss of the first two enamel deciles and abrasion of the outer enamel surface, particularly near the cusp. this loss of enamel necessitates that the leh and al counts, as well as the average enamel extension rate, are considered minimum values. cuspal enamel usually has the fastest extension rate in primate teeth (guatellisteinberg et al., 2012; mcgrath et al., 2019; shellis, 1998), meaning that the average eer reported in this study is likely lower than the actual rate due to the exclusion of the two lost cuspal deciles. the number of al and leh defects are also considered minimum counts in this study; since leh, and particularly al, defects are not confined to a limited section of the enamel, there are likely al and leh defects in the first two deciles that are not reported in this study. eers and leh defect perceptibility large-bodied monkeys, such as baboons and mandrills, usually have higher average anterior teeth eers than humans and extant great apes (dirks et al., 2002; mcgrath et al., 2019). table 2 shows mean eers for the anterior teeth of six primate taxa. the papio ursinus upper incisor belonging to individual b4-03 exhibited the highest mean eer (23.6 µm/ day) of all the primate taxa listed in table 2, despite the fact that the first two deciles (i.e., those with the highest eer) had to be excluded due to wear. mandrillus sphinx, the most closely-related species to papio ursinus in table 2, exhibits the second fastest mean eer (15.5 µm/day). male g. b. beringei (mountain gorillas) canines have the highest eers among the apes in table 2 at 12.7 µm/ day, but this is still lower than both of the aforementioned large-bodied monkey species. an examination of mountain gorilla incisors is needed in order to make direct comparisons with the data derived from the current study. high eer is typically associated with relatively acute striae of retzius angles, especially near the taxon tooth type number of specimens sex mean angle papio ursinus central incisor 2 m 13.5° g. b. beringei1 canine 2 m 18.5° gorilla gorilla2 central incisor 4 m, f 18.0° pan troglodytes2 central incisor 5 m, f 32.0° pongo pygmaeus2 central incisor 4 m, f 45.0° table 3. mean midcrown striae of retzius angles in the anterior teeth of five primate taxa. 1mcgrath et al. 2019. 2guatelli‐steinberg et al., 2012. 11 dental anthropology 2023 │ volume 36│ issue 02 cusp. table 3 shows the mean midcrown oes striae of retzius angles in the anterior teeth of five primate taxa. the mean striae of retzius angles of the two papio ursinus central incisors measured in this study exhibit the most acute mean midcrown oes angles of all the taxa listed in table 3 (13.3°). male g. b. beringei canines exhibit the second most acute striae angles in table 3 (18.5°), and are the acutest angles among the ape species listed. the very acute striae angles observed in these two incisors may produce very shallow leh defects on the surface (guatelli-steinberg et al., 2012; mcgrath et al., 2018, 2019), which are inherently less perceptible than deeper defects, particularly when using qualitative scoring methods. since the main tooth in this study exhibits much faster eers compared to apes, along with its acute striae angles, the difficulty in identifying leh defects on the surface of this tooth can be attributed to, at least in part, the high eers and acute striae angles found in this specimen. the low perceptibility of shallow leh in this tooth is further exacerbated by the intense feedinginduced teeth wear commonly seen in baboons. since leh defects are presumably very shallow in chacma baboons (though their depth is yet to be measured via profilometry), even relatively small amounts of tooth wear can obscure leh defects. this is evident towards the cusp, as the cusp is naturally subject to more wear pressure compared to the cervical and middle sections of the incisor. eers and striae angles the enamel extension rate gradient observed in this tooth likely contributed to more defined and deeper leh defects in regions with low eer (midcrown and cervix) compared to regions with high eer (cusp). this is potentially another factor contributing to the difficulty in locating cuspal leh defects. interestingly, a disconnection is observed between striae of retzius angles and eer, where, for example, the striae angles in deciles 7 and 8 are 14.0° and 13.7°, while the eers are 16.2 and 25.6 µm/day, both respectively. striae of retzius angles measured along the edj have been shown to serve as reliable proxies for eer estimations in human teeth (boyde, 1964; shellis, 1984), and at the oes, angles are strongly correlated with extension rates in ape canines (mcgrath et al., 2019). however, individual-level variation in ameloblast cellular activity (i.e., variable rates of enamel matrix secretion) might influence eers while not directly translating to a change in striae of retzius angles. other enamel structure parameters also influence eer, such as the angle between the forming prisms and the edj or the length of enamel prism formed per day (shellis, 1984), and may play a role in producing this unexpected decoupling between striae of retzius angles and eer in this specimen. future studies of multiple individuals will be able to assess whether this pattern occurs more broadly, and could incorporate measurements of daily secretion rates and geometric variables throughout the enamel thickness rather than just the oes. spatial distribution of al and leh defects in this analysis, accentuated lines were evenly distributed throughout the enamel. conversely, nine of the ten total leh defects were observed in the middle and cervical sections of the outer enamel, while only one defect was observed in the cuspal third. this confinement of leh distribution (which is not observed with accentuated line defects) can be attributed to a number of factors that serve to disconnect the two defect types, including the aforementioned dental wear. all but one of the leh defects were classed as minor in severity, meaning that they represent short-lived growth disruptions only affecting a very small number of similar perikymata growth increments. this study did not attempt to classify al based on their severity, though we did include even minor internal defects in the sample. future studies could incorporate severity scoring into al analyses to assess whether leh occur in the absence of more marked al, as has been proposed by kierdorf et al. (2000, 2004) and witzel et al. (2006, 2008), or if moderate to severe al usually underlie leh, as demonstrated by smith and boesch (2015). in permanent upper central incisors, enamel at the cusp is composed mostly of appositional enamel, while the remainder of the crown is composed mainly of imbricational enamel (hillson and bond, 1997). during the formation of appositional enamel, stress-associated enamel formation impairment may never manifest as leh on the surface, as the striae of retzius do not terminate at the outer enamel surface as is the case with imbricational enamel (witzel et al., 2008). this key difference suggests that histological examination of accentuated lines (as opposed to surface examination of leh) in teeth regions composed of appositional enamel is necessary to identify stress markers that do not extend to the oes. in this study, the cuspal enamel could not be analyzed due to wear, so the remaining eight deciles are comprised of entirely imbricational enamel where leh defects could 12 dental anthropology 2023 │ volume 36│ issue 02 manifest on the surface. future directions future work will focus on expanding the sample size to include more individuals and several other tooth types. incorporating life records of tracked individual baboons in both anthropogenic and rural environments can help in drawing connections between documented stress episodes (e.g., malnutrition, illness, or physical injury) and specific leh or al defects. it is important to note that accentuated lines and leh defects are disruptions in the normal enamel growth rate, meaning they can only manifest as the enamel is actively growing. consequently, the physiological stress episodes that resulted in leh and al defects happened within the developmental window of the examined tooth. different tooth types have different, and sometimes nonoverlapping, windows of development (reed, 1973). examination of a set of teeth from one individual can help with identifying stress episodes occurring over a larger span of an animal’s life compared to the examination of only a single tooth. profilometric analysis of the enamel surface can aid in the process of identifying leh defects in general (e.g., mcgrath et al., 2018), and especially toward the cusp where they tend to be either very shallow due to cuspal enamel geometry or obscured by normal tooth wear. profilometry can also be helpful in providing quantitative measurements of the various topographical characteristics of the enamel (defect depth, width, regularity, etc.), allowing for better definition of criteria for minor, moderate, and severe defects. conclusions we found a higher occurrence of internal al (n = 48) compared to external leh defects (n = 10), which co-occurred in all instances of leh. despite the loss of the first two deciles to normal wear, this incisor exhibited a fast mean eer of 23.6 µm/day, which is faster than several large-bodied monkey species reported in other studies (see table 2). with the inclusion of a second specimen for midcrown oes striae angle measurements, the mean angle measured was more acute than several primate taxa reported in other studies (see table 3). leh and al counts and mean eer reported in this study are considered minimum values, as enamel loss and surface abrasion prevented the analysis of the first two deciles, which likely exhibited the fastest eers and contained additional enamel defects. we offer the findings of this study as an initial exploration of the questions set out in the introduction, as our sample size is small. future work will expand sample size, utilize profilometric analysis of the enamel surface, and incorporate detailed life records of individual baboons to investigate links between documented stress episodes and leh or al defects. funding sources this project received funding from the ohio state university president’s postdoctoral scholars program and nsf grant 1945008. references ash, m., & nelson, s. (2003). wheeler’s dental anatomy, physiology, and occlusion (8th ed., p. 32). st. louis, missouri: saunders. beamish, e., & o’riain, m. (2014). the effects of permanent injury on the behavior and diet of commensal chacma baboons (papio ursinus) in the cape peninsula, south africa. international journal of primatology, 35(5), 1004-1020. doi: 10.1007/s10764-014-9779-z boyde, a. (1964). the structure and development of mammalian enamel. phd thesis, university of london, london, england. chowdhury, s., brown, j., & swedell, l. (2020). anthropogenic effects on the physiology and behaviour of chacma baboons in the cape peninsula of south africa. conservation physiology, volume 8, issue 1, 2020, coaa066. doi:10.1093/conphys/coaa066 condon, k., & rose, j. c. (1992). intertooth and intratooth variability in the occurrence of developmental enamel defects. journal of paleopathology, 2, 61-77. daegling, d., & grine, f. 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(1995). mammalian enamel prism patterns and enamel deposition rates. scanning microscopy: vol. 9: no. 2, article 12. retrieved from https://digitalcommons.usu.edu/ microscopy/vol9/iss2/12 galbany, j., romero, a., mayo-alesón, m., itsoma, f., gamarra, b., pérez-pérez, a., willaume, e., kappeler, p. m., & charpentier, m. j. (2014). age-related tooth wear differs between forest and savanna primates. plos one, 9(4), e94938. doi: 10.1371/journal.pone.0094938 goodman a.h., & rose j.c. (1990). assessment of systemic physiological perturbations from dental enamel hypoplasias and associated histological structures. yearbook of physical anthropology, 33: 59-110. doi: 10.1002/ajpa.1330330506 guatelli‐steinberg, d. (2016). chapter 27: dental stress indicators from micro‐ to macroscopic. in j. d. irish & g. r. scott (eds.), a companion to dental anthropology (pp. 450–457). west sussex, uk: wiley blackwell. guatelli-steinberg, d., & lukacs, j. r. (1998). preferential expression of linear enamel hypoplasia on the sectorial premolars of rhesus monkeys (macaca mulatta). american journal of physical anthropology, 107(2), 179–186. doi: 10.1002/ (sici)1096-8644(199810)107:2<179::aidajpa4>3.0.co;2-q guatelli-steinberg, d., ferrell, r., & spence, j. (2012). linear enamel hypoplasia as an indicator of physiological stress in great apes: reviewing the evidence in light of enamel growth variation. american journal of physical anthropology, 148(2), 191-204. doi: 10.1002/ajpa.21619 hillson, s., & bond, s. (1997). relationship of enamel hypoplasia to the pattern of tooth crown growth: a discussion. american journal of physical anthropology, 104(1), 89-103. doi: 10.1002/(sici)1096-8644(199709)104:1<89::aidajpa6>3.0.co;2-8 hoffman, t. s., & o’riain, m. j. (2011). the spatial ecology of chacma baboons (papio ursinus) in a human-modified environment. international journal of primatology, 32(2), 308-328. doi: 10.1007/s10764-010-9467-6 hoffman, t. s., & o'riain, m. j. (2012). troop size and human-modified habitat affect the ranging patterns of a chacma baboon population in the cape peninsula, south africa. american journal of primatology, 74(9), 853–863. doi: 10.1002/ ajp.22040 kansky, r., & gaynor, d. (2000). baboon management strategy for the cape peninsula (final report, table mountain fund project no. za 568). table mountain fund, cape town, south africa. kierdorf, h., kierdorf, u., richards, a., & josephsen, k. (2004). fluoride-induced alterations of enamel structure: an experimental study in the miniature pig. anatomy and embryology, 207(6), 463-474. doi: 10.1007/s00429003-0368-8 kierdorf, h., kierdorf, u., richards, a., & sedlacek, f. (2000). disturbed enamel formation in wild boars (sus scrofa l.) from fluoride polluted areas in central europe. the anatomical record, 259(1), 12-24. doi: 10.1002/(sici)1097-0185 (20000501)259:1<12::aid-ar2>3.0.co;2-6 lucas, p., constantino, p., wood, b., & lawn, b. (2008). dental enamel as a dietary indicator in mammals. bioessays, 30(4), 374-385. doi: 10.1002/bies.20729 mahoney, p., miszkiewicz, j. j., pitfield, r., deter, c., & guatelli-steinberg, d. (2017). enamel biorhythms of humans and great apes: the havers -halberg oscillation hypothesis reconsidered. journal of anatomy, 230(2), 272–281. doi: 10.1111/joa.12551 mcgrath, k., el-zaatari, s., guatelli-steinberg, d., stanton, m. a., reid, d. j., stoinski, t. s., cranfield, m. r., mudakikwa, a., & mcfarlin, s. c. (2018). quantifying linear enamel hypoplasia in virunga mountain gorillas and other great apes. american journal of physical anthropology, 166(2), 337–352. doi: 10.1002/ajpa.23436 mcgrath, k., reid, d., guatelli-steinberg, d., arbenz-smith, k., el zaatari, s., & fatica, l. et al. (2019). faster growth corresponds with shallower linear hypoplastic defects in great ape canines. journal of human evolution, 137, 102691. doi: 10.1016/j.jhevol.2019.102691 molnar, p. (2011). extramasticatory dental wear reflecting habitual behavior and health in past populations. clinical oral investigations, 15(5), 681–689. doi: 10.1007/s00784-010-0447-1 nanci, a. (2018). ten cate’s oral histology: development, structure, and function (9th ed., pp. 152154). st. louis, missouri: elsevier. o’hara, m. c., mcgraw, w. s., & guatellisteinberg, d. (2023). some orangutans acquire enamel defects at regular intervals, but not according to seasonal cycles. american journal of biological anthropology, 1– 15. doi: 10.1002/ ajpa.24690 preibisch, s., saalfeld, s., & tomancak, p. (2009). globally optimal stitching of tiled 3d microscopic image acquisitions. bioinformatics, 25 14 dental anthropology 2023 │ volume 36│ issue 02 (11), 1463-1465. doi: 10.1093/bioinformatics/ btp184 reed, o. m. (1973). papio cynocephalus age determination. american journal of physical anthropology, 38(2), 309–314. doi: 10.1002/ ajpa.1330380226 risnes, s. (1990). structural characteristics of staircase-type retzius lines in human dental enamel analyzed by scanning electron microscopy. the anatomical record, 226(2), 135–146. doi: 10.1002/ar.1092260203 shellis, r. p. (1984). variations in growth of the enamel crown in human teeth and a possible relationship between growth and enamel structure. archives of oral biology, 29(9), 697– 705. doi: 10.1016/0003-9969(84)90175-4 shellis, r. p. (1998). utilization of periodic markings in enamel to obtain information on tooth growth. journal of human evolution, 35(4-5), 387 -400. doi: 10.1006/jhev.1998.0260 skead, c. j. (1980). historical mammal incidence in the cape province (vol. 1). cape town, south africa: department of nature and environmental conservation of the provincial administration of the cape of good hope. smith, t.m. & boesch, c. (2015). developmental defects in the teeth of three wild chimpanzees from the taï forest. american journal of physical anthropology, 157: 556-570. doi: 10.1002/ ajpa.22741 stojanowski, c. m., johnson, k. m., paul, k. s., & carver, c. l. (2016). chapter 23: indicators of idiosyncratic behavior in the dentition. in j. d. irish & g. r. scott (eds.), a companion to dental anthropology (pp. 381–382). west sussex, uk: wiley blackwell. strum, s. c. (2010). the development of primate raiding: implications for management and conservation. international journal of primatology, 31(1), 133–156. doi: 10.1007/s10764-0099387-5 temple, d.h. (2014). plasticity and constraint in response to early-life stressors among late/ final jomon period foragers from japan: evidence for life history trade-offs from incremental microstructures of enamel. american journal of physical anthropology, 155: 537-545. doi: 10.1002/ajpa.22606 thylstrup, a. & fejerskov, o. (1978). clinical appearance of dental fluorosis in permanent teeth in relation to histologic changes. community dentistry and oral epidemiology, 6: 315-328. doi: 10.1111/j.1600-0528.1978.tb01173.x ungar, p. (1994). patterns of ingestive behavior and anterior tooth use differences in sympatric anthropoid primates. american journal of physical anthropology, 95(2), 197-219. doi: 10.1002/ ajpa.1330950207 witzel, c., kierdorf, u., dobney, k., ervynck, a., vanpoucke, s., & kierdorf, h. (2006). reconstructing impairment of secretory ameloblast function in porcine teeth by analysis of morphological alterations in dental enamel. journal of anatomy, 209(1), 93–110. doi: 10.1111/j.14697580.2006.00581.x witzel, c., kierdorf, u., schultz, m., & kierdorf, h. (2008). insights from the inside: histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth. american journal of physical anthropology, 136(4), 400-414. doi: 10.1002/ ajpa.20822 duncan 2009.2 39 case studies of supernumerary teeth have been recorded clinically at least since the paul of aegina discussed their treatment in the 7th century among the greeks, the 10th century in persia, and the 18th century in france and germany (guerini, 1909). although a rare trait, constituting a deviation in normal dental development, case studies of isolated supernumerary teeth are not uncommon in the clinical literature from around the world (garvey et al., 1999; orhan et al., 2006; rajab and hamdan, 2002; scheiner and sampson, 1997; solares and romero, 2004; see yusof, 1990; zhu et al., 1996 for review articles). case studies have also been reported in archaeological (alt, 1990) and paleontological contexts reaching back to earlier hominids (ripamonti et al., 1999). finding examples of nonsyndromic multiple supernumerary teeth is rarer however. in this paper i review what is known about frequency, nosology, location, ontogeny, function, and mode of inheritance of supernumerary teeth and describe cases from two archaeological contexts in mesoamerica. the first context is a postclassic maya temple at the site of ixlú in northern guatemala in which there were 21 skulls arranged in rows and pairs. three of these individuals had supernumerary mandibular teeth and 2 individuals exhibited them bilaterally. the second context is from oaxaca, mexico. an individual had one supernumerary tooth that was unerupted but visible due to broken mandible. i conclude the paper by discussing the cases’ relevance to biological distance analyses. background supernumerary teeth are typically classified with reference to number of teeth, morphology (kalra et al., 2005), and location. the number of teeth is clinically meaningful because multiple supernumerary teeth are typically syndromic (fernández montenegro et al., 2006; garvey et al., 1999) and because increased numbers of teeth are more likely to require intervention (högström and andersson, 1987). fernández montenegro et al. (2006) classify morphology as eumorphic (retaining the normal features of a member of the tooth field in which they develop) and heteromorphic. they divide heteromorphic teeth into conical, tuberculate, molariform, and infundibular. garvey et al. (1999) divide morphology into conical, tuberculate (having multiple cusps, which includes invaginated or barrel shaped teeth), supplemental (eumorphic), and odontome (further classified as either complex or compound). the last category, odontomes, is not universally agreed upon as a supernumerary tooth class (de oliveira gomes, 2008; garvey et al., 1999). in addition to normal tooth fields, location is frequently categorized as mesiodens, distomolars, or paramolars (fernández montenegro, 2006). however, some teeth that are inverted can also be classified as nasal (alt, 1990; hiranandani and melgiri, 1968). assessments of population percentages exhibiting supernumerary are fairly consistent in the literature and range from 0.1-3.6% when including all teeth (brook, 1974; liu, 1995; hopcraft, 1998; scheiner and sampson, 1997; see luten, 1967 for review of earlier studies). separating permanent and deciduous teeth suggests that the phenomenon is more common in the former (0.5-3.8%) than the latter (0.3-0.6%; fernández supernumerary teeth from two mesoamerican archaeological contexts william n. duncan* department of anthropology, st. john fisher college, rochester, ny *correspondence to: william n. duncan, department of anthropology, st. john fisher college, 3690 east avenue, rochester, ny 14620 e-mail: bduncan@sjfc.edu abstract: supernumerary teeth are uncommon but have been well documented clinically. the majority of cases are isolated anterior teeth; examples of multiple or posterior supernumerary teeth are less common. this paper describes two examples of supernumerary teeth from archaeological contexts in mesoamerica. the first case is of three individuals with supernumerary posterior teeth found in skull rows and pairs in a postclassic maya temple at the site of ixlú in northern guatemala. two of these individuals exhibited bilateral supernumerary mandibular teeth. the second context is a zapotec burial from the jalieza site in oaxaca, mexico. this individual exhibited a single supernumerary tooth. the paper reviews supernumerary teeth with regard to frequency, ontogeny, and mode of inheritance and discusses the cases’ relevance for biological distance analyses. dental anthropology 2009;22(2):39-46. 40 montenegro et al., 2006; scheiner and sampson, 1997). the majority of these cases are single teeth (77-86%; orhan et al., 2006; scheiner and sampson, 1997; rajab and hamdan, 2002). cases of multiple supernumerary teeth are less common and most often associated with syndromes, such as gardner syndrome, or cleft lip and palate, or cleidocranial dysplasia. orhan and colleagues (2006) note that over 20 conditions have been associated with supernumerary teeth. nonsyndromic cases of supernumerary teeth (hyperdontia) have been reported occasionally in the literature as well, though they are rarer (bayar et al., 2008; desai and shah, 2007; gündüz and muğlali, 2007; kalra et al., 2005; king, 1993; leite et al., 2007; leslie, 1984; moore et al., 2002; manrique morá et al., 2004; mopager et al. 2002; rosenthaler and beideman, 1983; ruhlman and neely, 1964; orhan et al., 2006; refoua and arshad, 2006; sasaki et al., 2007; sharma, 2001; yusof and awang, 1990; yusof, 1990; zhu et al., 1996; see references therein for earlier case studies and açikgöz et al., 2006 in particular for review). it should be noted that some researchers quantify supernumerary teeth as single teeth, doubles, or multiples, but count the latter category as having more than 5 extra teeth (e.g., arathi and ashwini, 2005; scheiner and sampson, 1997), although it is unclear if this classification has any etiological basis. the highest number of nonsyndromic supernumerary teeth i have seen in the literature is 22, in a 10-year-old male (rizzuti and scotti, 1997). açikgöz et al. (2006) found a frequency of 0.06% of all cases of supernumerary teeth exhibited multiple teeth in a retrospective study. de oliveira gomes et al. (2008) found 37% of individuals with supernumerary teeth had more than 1, but only 2% had 5 or more. males are more affected by supernumerary teeth than females, and the reverse is true for congenital absence of teeth (brook, 1974). rajab and hamdan (2002) report a male to female ratio of 2.2:1. similar numbers were found by other studies (mason et al., 2002; mitchell, 1989), but higher and lower estimates exist. davis (1987) found a ratio of 6.5 males to every female in a sample of 1,093 hong kong school children (2.74% with a 95% confidence interval of ± .9604%). brook (1974) however found a male to female ratio of 1:0.7 among 1,115 white british school children (2.1% with a 95% confidence interval of ± 0.83%). given the overlapping confidence intervals in the estimates, the difference in sex ratio may be due to variation between populations or sampling fluctuation. there is some variability reported regarding the overall frequency of supernumerary teeth among populations. brown (1990) and zhu et al. (1996) report that subsaharan african and asian populations exhibit somewhat higher prevalence (between 2.7% and 3.4%) than that found in brook (1974) and luten (1967). that said, the relative population frequencies among the different categories and locations of supernumerary teeth are still unknown, so accurately characterizing interpopulation variability remains difficult. some studies report the most common supernumerary teeth are mesiodens (see garvey et al., 1999; refoua and arshad, 2006), which may reflect a high representation of european data in the literature because variation exists. luten (1967) found the most common locations (in decreasing order) to be upper lateral incisors, mesiodens, upper central incisors, and premolars when both permanent and deciduous dentitions were combined. orhan et al. (2006:891-892) note that the most common supernumerary teeth are mesiodens, followed in descending frequency by “maxillary fourth molars, maxillary paramolars, mandibular premolars, maxillary lateral incisors, mandibular fourth molars, and maxillary premolars.” also, fernández montenegro et al. (2006) found lateral incisors and canines to be rare relative to other, distal positions. thus, while most studies find increased frequency in maxillary and anterior position, there is variability. there does seem to be agreement that when multiple nonyndromic supernumerary teeth are present, they are most often premolars (açikgöz et al., 2006; solares and romero, 2004). as noted, multiple supernumerary teeth frequently are associated with syndromes. the actual mechanism resulting in supernumerary teeth is often attributed to independent, hyperactivity of the dental lamina in a localized context (solares and romero, 2004). another explanation is that after supernumerary teeth could emerge from a dichotomized tooth bud (brook, 1984; leite, 2007; moore et al. ,2002; see d’souza and klein, 2007 for review). a third, but less cited explanation is an atavistic origin (hattab et al., 1994; marya and kumar, 1998). development of supernumerary teeth can happen at different times in life. järvinen (1976) documented a case in which supernumerary teeth were extracted in a child and later x-rays disclosed that more supernumerary teeth had developed. what does seem clear is that although there may be some non-genetic or epigenetic involvement (suda et al., 2007), there is a genetic component (batra et al., 2005; becker et al., 1982; desai and shah, 2007; langowska-adamcyżk and karmaňska, 2001; marya and kumar, 1998; mercuri and o’neill, 1980; umweni and osunbor, 2002) and it does not appear to be the result of simple mendelian inheritance (yusof, 1990). studies have suggested that transmission of supernumerary teeth may be autosomal dominant (batra et al., 2005) or sex linked (hattab et al., 1994), the latter scenario might account for the higher frequencies in males. case 1 – ixlú at the maya site of ixlú, in northern guatemala, 21 skulls were found in pairs and rows in a postclassic temple (structure 2023; fig. 1). the skulls were visually examined and were not radiographed. three of these w.n. duncan 41supernumerary teeth from mesoamerica individuals exhibited supernumerary teeth (skulls 1, 7, and 16). all of these teeth were erupted with the exception of the left side supernumerary tooth on individual 1 (see below). six skulls had been placed in pairs on the midline on the east and west sides of the building (skulls 1, 2, 3, 4, 5, and 6) in a late construction stage. postcranial remains of 4 individuals were placed on top of this floor as well on the west side of the building perpendicular to the skull pairs. the postcrania lacked hand, foot, or cranial elements and exhibited cutmarks at the joints of the long bones. the long bones were placed on top of the axial skeletons in bone bundles (duncan, 2005). the other skulls were placed in rows above the skull pairs, above a lower floor in the center of the building. it should be noted that there were two episodes of deposition and that skulls 1 and 2 appear to have been interred at the same time as the skull row (duncan, 2005). skulls 3, 4, 5, and 6 likely correspond to the four postcrania found behind the temple, though individuation proved impossible. all of the skulls were seated on the floors and faced east except for those clearly overturned by root action. all skulls except for 2, 10, 11, 15, 18 had articulated cervical vertebrae underneath them. it should be noted that skulls 10 and 11 were only represented by fragments of cortical bone and could not be identified as separate skulls osteologically in laboratory analysis. however, they intersected a looter’s trench, and it is parsimonious to include them in the final count of 21. it is likely that other skulls were also part of the rows and were originally located to the south of skull 13 prior to looting (fig. 1). sex was assessed by the use of standard anthroposcopic features described in buikstra and ubelaker (1994), with the omission of the mastoid process, which may be artificially hypertrophied in this culture area due to tumpline use. three of the skulls in pairs and 8 of the skulls in rows could be assessed for sex, all of which were male (including skulls 1 and 7). poor preservation precluded using cranial suture closure to assess age, but all of the skulls that could be observed were either late adolescent to adult in age on the basis of dental eruption. markers that may have been used to distinguish young versus older adulthood (the sphenoccipital synchondrosis and the palate sutures) were not observable. two of the skulls (2 and 5) exhibited frontooccipital cranial modification and skull 13 exhibited dental modification (romero [1970] iii-6 style). skull 1, an adult male, exhibited bilateral supernumerary mandibular teeth. on the left side, the tooth was found between p4 and m1 and was lingual to the tooth row (fig. 2). the tooth was tuberculate with a dominant buccal cusp and a weak lingual cusp. a small accessory mesial cusp was visible as well (fig. 3). no occlusal wear was visible on the tooth, and it would not have been in contact with maxillary teeth. the alveolar bone was broken around this tooth, but it may not have been emerged in life. there is no evidence that it displaced fig. 1. position of skulls in pairs and rows at structure 2023 in ixlú, guatemala. locations are denoted by positions of the numbers, 1 through 21. pc stands for postcranial remains. fig. 2. supernumerary teeth in skull 1, ixlú, guatemala. there is an extra premolar lingual to the distal premolar on the specimen’s left side. note that there also is a extra, conical tooth on right side of the jaw. 42 other teeth. the root appears to be incisiform, and no radicals were visible. the right side supernumerary tooth was between the canine and p3 and was also lingual to the tooth row (fig. 2). it was conical with slight lingual invagination and had no occlusal wear. the tooth root was broken near the cementoenamel junction. poor preservation precluded assessing if the adjacent teeth would have been displaced. there is no evidence that other teeth were altered in size. skull 7, an adult of unknown sex, exhibited bilateral supernumerary mandibular teeth. the left supernumerary tooth was lingual to p3, displacing it buccally (fig. 4). the supernumerary tooth was molariform, exhibiting 5 cusps and had a talonid. it was in occlusion and the roots could not be observed. no wear was present, and it would not have made contact with maxillary teeth unless other teeth had worn down considerably more. the right supernumerary tooth was between p3 and p4, though mesial to the tooth row (fig. 5). it was tuberculate, exhibiting a single primary cusp and an accessory distal cusp. the tooth was not well preserved and the apex of the root was broken. it was not in occlusion and it is unclear if it would have displaced other teeth. there is no evidence that other teeth were altered in size. skull 16, a late adolescent to adult of unknown sex, exhibited a single supernumerary mandibular tooth (fig. 6). the tooth was mesial to the other premolars and between p3 and p4 on the right side. the tooth was tuberculate with a dominant buccal cusp and 2 lingual cusps of roughly equal size. the buccal side exhibited fig. 3. supernumerary tooth on left side from skull 1, ixlú, guatemala. occlusal view from the buccal side. scale 5 mm. photo courtesy david long. fig. 4. supernumerary tooth on left side from skull 7, ixlú, guatemala. fig. 5. supernumerary tooth on right side from skull 7, ixlú, guatemala. occlusal surface from lingual view. distal cusp is on the right. scale 5 mm. photo courtesy of david long. w.n. duncan 43supernumerary teeth from mesoamerica 2 grooves on it. the tooth was not in occlusion and no wear was evident. the root was longer buccolingually than mesiodistally and exhibited no radicals. the apex of the root was not closed. preservation precluded observing whether or not other teeth were displaced because of the supernumerary tooth, though it is likely that it did given its size and locarion. the third molars were bilaterally somewhat smaller than the other teeth, though it is unclear if this stems from the supernumerary tooth. case 2 jalieza the second context that yielded a supernumerary tooth was a late classic period burial from the zapotec site of jalieza in the oaxaca valley. the individual was an adult male. the supernumerary tooth was unerupted and was only visible because the surrounding alveolar bone was broken. the dentition was visually assessed and was not confirmed with an x-ray. the tooth was visible on the left buccal side of the mandible and was between p3 and p4 (fig. 7). it was superior and mesial to the mental foramen. neither the crown nor root morphology was visible. there was no evidence of displacement of any of the teeth but the third molar on the left side was absent (fig. 8). discussion the ixlú case stands out primarily because of the likelihood of finding three individuals in such a small sample with supernumerary teeth is so low. there have been no studies on the frequency of supernumerary teeth in mesoamerican populations, but two maya biodistance studies have found them. jacobi (2000) found 3 cases of supernumerary teeth at tipu out of over 500 burials. two were single teeth and 1 individual had 2 supernumerary teeth. all were maxillary. lang (1990) found a total of 13 supernumerary teeth in her study at lamanai out of 89 individuals. six of these were maxillary and resemble jacobi’s description. however, 7 were mandibular and resemble what i found at ixlú, based on lang’s (1990) description. in a clinical context hopcraft (1998) found that 1.6 to 3.1% of people have supernumerary teeth but only 3 to fig. 6. supernumerary tooth from skull 16, ixlú, guatemala. scale is 5 mm. photo courtesy of david long. fig. 7. supernumerary tooth from individual at jalieza, oaxaca, mexico. this tooth (unerupted) is visible in the alveolus because it has resorbed the buccal aspect of the bone adjacent to it. its position is between the roots of the two erupted premolars. scale 5 mm. fig. 8. absence of left mandibular third molar from individual at jalieza, oaxaca, mexico. scale 5 mm. 44 10.9% of supernumerary teeth are in the premolar field, a range consistent with aforementioned citations. if one accepts the interval of 1.6 to 3.1% as the range of frequencies for some manifestation of supernumerary teeth (and there is no current evidence to think it is more common among the maya than that) the average is 2.35%, and the average of 3% and 10.9% is 6.95%. 6.95% of 2.35% is 0.16% or a 1 in 625 chance of having this trait. i used the resampling software (and modified the “birthday program”; simon, 1990) to estimate the likelihood of finding 3 of 17 individuals having mandibular supernumerary teeth with this frequency. only 17 individuals were observable for the trait. if the likelihood of finding mandibular supernumerary teeth is 1 in 625, then one can randomly select 17 numbers from 625. this was repeated 10,000 times, out of which 17 times or 0.2% that the same number came up 3 times, which is statistically significant and suggests that the individuals were likely related, although at what level remains unclear. the two cases described here also highlight three potential problems with using supernumerary traits in biodistance analyses. the first problem, highlighted by the jalieza case, is that many supernumerary teeth are subclinical in life and invisible in death because they do not emerge so including them in such analyses may actually obscure relationships. this is consistent with açikgöz et al. (2006) who found 30 of 37 supernumerary teeth they studied to be impacted. certainly such traits have utility, but are other people in the skull rows and pairs who have supernumerary traits just not being counted? the second problem, also highlighted by the jalieza case, is that there may be interactions between tooth fields. the congenital absence of the third molar on the same side may or may not be due to the supernumerary tooth, but accounting for the correlation if you are using both as separate traits is necessary. this may mimic examples in which supernumerary teeth were found in conjunction with atypical morphodifferentiation (manrique morá et al., 2004). finally, the ixlú cases suggest that supernumerary teeth likely should be scored as present or absent in biodistance analyses. the fact that the left supernumerary tooth is highly molariform and the right is much simpler in skull 7 at ixlú may suggest that influences reflect environmental influence. similar heterogeneity has been found in individuals with many more supernumerary teeth as well (so, 1990). this could be true whether they are attributable to the splitting of the tooth bud or localized or independent activity of the lamina. acknowledgements i would like to thank dr. rob corruccini for his input on this and related projects over the last 10 years (dental and otherwise). the remains from ixlú were excavated under the auspices of proyecto maya colonial directed by drs. prudence m. rice, don s. rice, and lic. romulo sanchez polo, whom i would also like to thank. figure 1 was originally drawn in the field by lic. ivo romero. david long kindly made the photographs used in figures 3, 5, and 6. the excavations in guatemala were completed with permission from idaeh and able assistance from its inspectors lic. boris aguilar and sheila flores. in mexico, the remains were excavated as a part of the jalieza project with drs. christina elson and luca casparis, with whom i am grateful to work, and with kind permission from inah. funding for this project was given in part by the national science foundation (bcs #0125311), the american museum of natural history, national geographic, and st. john fisher college. all errors remain my own. literature cited açikgöz a, açikgöz g, tunga u, otan f. 2006. characteristics and prevalence of non-syndrome multiple supernumerary teeth: a retrospective study. dentomaxillofac radiol 35:185-190. alt k. 1990. nasal teeth: report of a historic case. int j anthropol 5:245-249. arathi r, ashwini r. 2005. supernumerary teeth: a case report. j indian soc pedod prev dent 23:103-105. bayar gr ortakoglu k, sencimen m. 2008. multiple impacted teeth: report of 3 cases. eur j dent 2:73-78. batra p, duggal r, parkash h. 2005. non-syndromic multiple supernumerary teeth transmitted as an autosomal dominant trait. j oral pathol med 34:621625. becker a, bimstein e, shteyer a. 1982. interdisciplinary treatment of multiple unerupted supernumerary teeth: report of a case. am 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2006. an unusual case of bilateral maxillary and mandibular supernumerary teeth. j dent tehran u med sci 3:140-142. ripamonti u, petit jc, thackeray jf. 1999. a supernumerary tooth in a 1.7 million-year-old australopithecus robustus from swartkrans, south africa. eur j oral sci 107:317-321. rizzuti n, scotti s. 1997. a case of hyperodontia with twenty-two supernumeraries: its surgical-orthodontic treatment. am j orthod dentofacial orthop 111:471-480. romero j. 1970. dental mutilation, trephination, and cranial deformation. in: stewart t, editor. physical anthropology. handbook of middle american indians. vol. 9. austin: university of texas. p 50-67. rosenthaler h, beideman rw. 1983. multiple supernumerary teeth. oral surg oral med oral pathol 56:227. rhulman d, neely ar. 1964. multiple impacted and erupted supernumerary teeth: report of a case. oral surg oral med oral pathol 17:199-203. sasaki h, funao j, morinaga h, nakano k, ooshima,t. 46 2007. multiple supernumerary teeth in the maxillary canine and mandibular premolar regions: a case in the postpermanent dentition. int j paediatr dent 17:304-308. scheiner m, sampson wj. 1997. supernumerary teeth: a review of the literature and four case reports. aust dent j 42:160-165. sharma a. 2001. a rare non-syndrome case of concomitant multiple supernumerary teeth and partial anodontia. j clin pediatr dent 26:167-169. simon j. 1990. resampling stats. arlington, va: resampling stats, inc. so ll. 1990. unusual supernumerary teeth. angle orthod 60:289-292. solares r, romero mi. 2004. supernumerary premolars: a literature review. pediatr dent 26:450-458. suda n, hamada t, hattori m, torii c, kosaki k, moriyama k. 2007. diversity of supernumerary tooth formation in siblings with cleidocranial dysplasia having identical mutation in runx2 : possible involvement of non-genetic or epigenetic regulation. orthod craniofac res 10:222-225. umweni a, osunbor ge. 2002. non-syndrome multiple supernumerary teeth in nigerians. odontostomatol trop 25:43-48. yusof w. 1990. non-syndrome multiple supernumerary teeth: literature review. j can dent assoc 56:147-149. yusof w, awang mn. 1990. multiple impacted supernumerary teeth. oral surg oral med oral pathol 70:126. zhu j, marcushamer m, king dl, henry rj. 1996 supernumerary and congenitally absent teeth: a literature review. j clin pediatr dent 20:87-95. w.n. duncan al-shorman 2008.3 18 the 3rd century ad was a turning point in late antiquity as the roman empire collapsed economically due to military invasions by germanic tribesmen, civil wars, and plague. as a result, the military remained unfunded, and emperors confiscated goods, imposed heavy taxes, and exacted forced labor to overcome the crises. the accumulation of factors resulted in economic havoc and famine (jones, 1964). the third century crises and weakness of the roman empire lessened its authority in the east, where turmoil and instability would have occurred. many of the people in the east empire were pushed into marginal lands away from cities to seek their livelihoods in food production. during this time, the majority of people lived in small rural sites that became economically independent. economic prosperity was obvious in many rural sites in jordan and the region (kingsley and decker, 2001; mango, 1980; parker, 1999; ward-perkins, 2000a,b; watson, 2001). this prosperity included wine trade, the import of skilled craftsmen, and the building of fancy tombs. the present study reviews the tomb architecture and the human skeletons at natfa in northern jordan. the site is located 4 km west of the city of irbid on a fertile landscape with a varied terrain, where the elevation ranges from 620 to about 695 m above sea level. cemeteries were found on the steep slopes of two opposing mountains at an elevation of about 650 m. the site was excavated jointly by yarmouk university and the university of arkansas starting in the summer of 2005. this is a rural late antiquity site in the north of jordan. successive excavations have revealed tombs, artifacts, cisterns, and archeological structures. there are 39 excavated tombs at the site, and all are horizontal shaft tombs with or without an arched entrance sometimes leading to loculi (fig. 1) except for tomb 21 that is a horizontal chamber tomb with radiating loculi (fig. 2). there is evidence of tomb robbing both in antiquity and in modern times. the recovered bones short communication: the biology of natfa people: bones and teeth abdulla al-shorman department of anthropology, faculty of archaeology and anthropology, yarmouk university, irbid, jordan correspondence to: abdulla al-shorman, department of anthropology, faculty of archaeology and anthropology, yarmouk university, irbid, jordan. e-mail: alshorman@yu.edu.jo abstract: the archeological site of natfa is a rural late-antiquity site in northern jordan. the tomb typology points to two social ranks: the public compared to the few elites who might have controlled wealth allocation. the people died at young ages (under 35 years of age). there seems to be reliance on hard food particles rich in carbohydrates, which increased the occurrence of interproximal caries. a few oblique dental caries are reported, probably caused by using teeth as tools. dental anthropology 2008;21(1):18-20. fig. 1. a horizontal shaft tomb from natfa with an arched entrance. were commingled except for 5 individuals. results and discussion due to the nature of the bones, we were able to sex 9 skeletons using the standards of buikstra and ubelaker (1994); 4 were female and 5 male. seven of the burials could be aged, with a range of from 7 to 35 years. none of these human remains show any paleopathological lesion except for an osteophytosis in one lumbar vertebra. 19 the examined teeth showed marked hypoplasia on most of the anterior teeth (fig. 4). the average dental wear score for the anterior teeth is 6 (namely, large dentine area with enamel rim lost on one side), and average dental wear on the posterior teeth is 23 (moderate dentine exposure). the few recovered teeth show only interproximal caries in an advanced stage of wear (i.e., exposed pulp cavities). a few cases of oblique dental wear were recorded, where enamel was lost obliquely down to the labial and buccal root cervix (fig. 5). excluding tomb 21, the tomb typology at the site of natfa was simple (horizontal shafts) and did not required extensive energy expenditure for construction. according to binford (1971) and tainter (1975) greater energy expenditure in tomb construction (and tomb complexity) corresponds to higher social rank of the deceased. this probably means that the horizontal shaft tombs were constructed for the public, while tomb 21 was for elites. based on the biological data extracted from the skeletal remains and teeth, the diet of the people of natfa was moderately hard as the average score of dental wear for the posterior teeth is moderate. this type of wear has been associated with abrasive diets of a vegetable type rich in carbohydrates, mostly cereals. considerable amounts of cereals and legumes were present in the diets of the mediterranean region during the roman period (prowse et al., 2004; garnsey, 1999), which extensively wear the enamel. the interproximal caries are explained by dental wear; in groups whose nutrition is based on foods that abrade grinding surfaces, higher frequencies of interproximal caries are recorded (calglar et al., 2007) because the wear removes food particles and bacteria. although the number of recorded oblique dental wear is few, it stresses the use of teeth as tools. oblique dental wear is noticed in societies who used their teeth in nonalimentary activities such as tooth-tool use and the use of teeth as a third hand (minozzi et al., 2003), including leather processing by eskimos (merbs, 1983), sinew processing by australian aboriginals (brown and molnar, 1990), basket production by native american paiute (wheat, 1967), and weaving by the byzantines in khirbit yajuz, jordan (al-shorman and khalil, 2006). conclusions the late roman people of natfa experienced environmental stresses. they died at young ages, evidently by around 35 years. as their skeletal remains were healthy, nothing could be inferred about the cause of death. the society was stratified into wealthy and poor. rural sites such as natfa may have established their economic independence at the expense of quality of life. references cited al-shorman a, khalil l. 2006. the evidence of weaving at khirbit yajuz in jordan using dental microwear. int j dent anthropol 8:1-9. binford r. 1971. mortuary practices: their study and their potential. in: brown j, editor. approaches to the social dimensions of mortuary practices. mem soc am archaeol 25, p. 6-20. brown t, molnar s. 1990. interproximal grooving and task activity in australia. am j phys anthropol 81:545-553. buikstra je, ubelaker dh. 1994. standards for data collection from human skeletal remains: proceedings of fig. 2. (left) top plan and a 3-dimensional representation of tomb 21; (right) a horizontal chamber tomb at natfa. fig. 3. the moderate dental wear on the posterior teeth. biology of natfa people 20 a seminar at the field museum of natural history (arkansas archeological report research series). fayetteville, ak: arkansas archeological society, 1994. calglar e, kuscu o, sandalli n, ari f. 2007. prevalence of dental caries and tooth wear in a byzantine population (13th c. ad) from northwest turkey. arch oral biol [in press]. garnsey p. 1999. food and society in classical antiquity. cambridge: cambridge university press. grant m. 1995. greek and roman historians: information and misinformation. new york: routledge. jones a. 1964. the later roman empire 284-602: a social, economic and administrative survey, 3 vols. oxford: blackwell. kingsley s, decker m. 2001. economy and exchange in the east mediterranean during late antiquity. oxford: oxbow books. mango c. 1980. byzantium: the empire of new rome. london: wardenfeld and nicolson. merbs c. 1983. patterns of activity-induced pathology in a canadian inuit population. ottawa: national museum of man mercury series, archaeological survey of canada papers, no. 119. minnozi s, moazi g, ricci f, lernia s, tarli s. 2003. nonalimentary tooth use in prehistory: an example from early holocene in central sahara (von muhuggiag tadrart acacus, libya). am j phys anthropol 120:225-232. parker s. 1999. the byzantine period: an empire’s new holy land. near eastern archaeology 6:134-181. prowse t, henry p, schwarcz h, saunders s, macchiarelli r, bondioli l. 2004. isotopic paleodiet studies of skeletons from the imperial roman-age cemetery of isola sacra, rome, italy. j arch sci 31:259–272. tainter j. 1975. social inference and mortuary practice: an experiment in numerical classification. world arch 7:1-15. ward-perkins b. 2000a. land, labor and settlement. in: cameron b, ward-perkins b, whitby m, editors. the cambridge ancient history. cambridge: cambridge university press, p. 315-341. ward-perkins b. 2000b. specialized production and exchange. in: cameron b, ward-perkins b, whitby m, editors. the cambridge ancient history. cambridge: cambridge university press, p. 346-389. watson p. 2001. the byzantine period. in: macdonald b, adams r, bienkowski p, editors. the archaeology of jordan. sheffield, uk: sheffield academic press. wheat m. 1967. survival arts of the primitive paiutes. reno: university of nevada press. white, k. 1976. food requirements and food supplies in classical times in relation to the diets of the various classes. progress in food nutrition and science 2:143–191. fig. 4. marked hypoplasia on the anterior teeth. fig. 5. oblique dental wear on the upper first premolar. fig. 6. interproximal caries in a lower third molar. a.al-shorman sperber 2016.1 48 dental anthropology 2016 │ volume 29 │ issue 01 as the 29th addition to the book series, “blackwell companions to anthropology”, this is a welcome and much needed inclusion to the burgeoning fields of dental anthropology. with an illustrated hard cover depicting the late christy g. turner ii at work, two neolithic male crania and dental pathology in a swazi skull from the renowned dart collection at the university of the witwatersrand, the book’s comprehensive encompassment of components of dental anthropology in nine parts and 31 chapters is a tour de force in hominin odontology. with a list of 41 authors that comprise the “whose who” of the dental anthropology canon, this work is destined to become a cornucopia of odontological inquiry. the contents of this book transcends brothwell’s “dental anthropology” (1963), kelly and larsen’s “advances in dental anthropology” (1991), and hillson’s “dental anthropology” (1996) by the incredible advances in instrumentation and imaging techniques, isotopic, dna and genetic analyses and the paleoanthropological discoveries made in the past quarter century. the nine parts of the book deal with context, dental evolution, the human dentition, dental growth and development, dental histology, dental morphometrics, dental health and disease and finally, the future of dental anthropology. each chapter concludes with an extensive list of references that range from retzius (1837) to among the most current (irish jd et al., 2014), constituting an absolute treasury of the odontognathic masticatory literature. the continuing expansion of dental anthropology into related fields is exemplified by the affinity of diets to dentitions (forshaw, 2014; morin et al., 2016). readers of this tome should be aware that, as much as the contents are current, the rapidly developing expansion of dental relevance in related fields of diets, genetics and paleo-odontology (hlusko, 2015; zinc and lieberman 2016) is mandatory for contemporary study of this discipline. a whole new archeological source of paleodietary investigation of ancient dental calculus allowing for paleogenetic analysis of mitochondrial genomes providing maternal lineage ancestry is being revealed (ozga et al., 2016). the book is unreservedly recommended for students and scholars of odontology, dental evolution, masticatory anatomy, forensics, and related fields. g.h. sperber faculty of medicine and dentistry university of alberta, edmonton references cited brothwell dr (1963). dental anthropology. new york: pergamon press. forshaw r (2014). dental indicators of ancient dietary patterns: dental analysis in archaeology. brit dent j. 216:529-535. hillson sw (1996). dental anthropology. cambridge: university of cambridge press. hlusko lj. (2015). elucidating the evolution of hominid dentition in the age of phenomics, modularity, and quantitative genetics. annal anat doi: 10.1016/j.aanat.2015.05.001. irish jd, guatelli-steinberg d, legge ss et al. (2014). response to ‘non-metric dental traits and hominin phylogeny’ by carter et al., with additional information on the arizona state university dental anthropology system and phylogenetic ‘place’ of australopithecus sediba. j hum evol 69:129-135. kelly ma and larsen cs ( 1991) advances in dental anthropology. new york: wiley-liss. morin e, speth jd, lee-thorp j (2016). middle palaeolithic diets: a critical examination of the evidence. the oxford handbook of the archaeology of diet. doi: 10.1093/ oxfordhb/97801199694013.013.24. ozga at, nieves-colon ma, honap tp et al. (2016). successful enrichment and recovery of whole mitochondrial genomes from ancient human dental calculus. am j phys anthropol. http://onlinelibrary.wiley.com/doi:10.1002/ ajpa.22960. retzius a. (1837). bemerkungen uber den inneren bau der zhane. arch anat phys wissenschaft med 1857. 486-566. zink kd, lieberman de (2016). impact of meat and lower palaeolithic food processing techniques on chewing in humans. nature doi:10.1038/nature16990. book review a companion to dental anthropology. joel d. irish and g. richard scott., editors. published in oxford by wiley-blackwell , 2016. pp. xviii + 540. illus. indexed. isbn 978—1-118-84543-1, price: us$195.00; can$215.00, ebook can$172.99. 8 dental anthropology 2019 │ volume 32 │ issue 01 global distribution of marginal accessory cusps of the maxillary premolars donovan m. adams 1* , victoria m. swenson 1 , and g. richard scott 1 1 department of anthropology, university of nevada, reno, nv usa despite marginal accessory cusps of the maxillary premolars comprising part of the arizona state university dental anthropology system (asudas; turner et al., 1991), few data are available on their geographic distribution (hanihara, 2008; reyes-centeno et al., 2017; scott and irish, 2017). this trait is characterized by additional cusps on either the mesial, distal, or both margins of the maxillary premolar apart from the primary buccal and lingual cusps. these are distinguished from the primary cusps by discrete parallel grooves (figures 1 and 2). to be scored as a premolar accessory cusp, there has to be separating grooves (turner et al., 1991). according to the asudas, this trait is scored as present or absent (turner et al., 1991). however, recent revisions to the asudas published by scott and irish (2017) have amended scoring to specify where these cusps are located: grade 0: marginal accessory cusp is absent. grade 1: marginal accessory cusp is mesial. grade 2: marginal accessory cusp is distal. grade 3: marginal accessory cusps are present on the mesial and distal margin. marginal accessory cusps have been identified in ancient hominins. this trait has frequently been noted in individuals of likely neanderthal identifiabstract the present study assesses the global distribution of marginal accessory cusps of the maxillary premolars. this trait, despite constituting one of the variables standardized by turner and colleagues (1991), has received little attention in morphological studies. frequencies were calculated from data sheets collected by christy g. turner ii for mesial, distal, and mesial + distal grades. different geographic patterns were identified for both types of expression on the upper premolars. the patterned geographic distribution of these traits indicates their utility in biodistance investigations. in addition, the distinction between mesial and distal accessory cusps specified by scott and irish (2017) is recommended, as these two traits exhibit different geographic patterns. *correspondence to: donovan m. adams department of anthropology university of nevada, reno keywords: marginal accessory cusps, maxillary premolars, asudas, dental morphology figure 1. mesial marginal accessory cusp on the left fourth premolar. note the grooves separating the accessory cusp from the primary cusps. figure 2. mesial marginal accessory cusp present on right fourth premolar. note the grooves separating the accessory cusp from the primary cusps. 9 dental anthropology 2019 │ volume 32 │ issue 01 cation (bailey, 2002; bailey and hublin, 2006; glatz et al., 2008; benazzi et al., 2011; hershkovitz et al., 2016). some argue that more complex occlusal morphology of the maxillary premolars, including accessory ridges and cusps, is characteristic of neanderthals compared to anatomically modern humans (benazzi et al., 2011). bailey (2002) notes these cusps occur in a high frequency in neanderthals, particularly on the third premolar, with the distal cusps occurring almost twice as often as mesial accessory cusps. in addition to neanderthals, grade 3 expression of this trait was identified in hominin remains from dmanisi, georgia (martinón-torres et al., 2008). few studies have explicitly addressed the frequency of this trait in modern humans. a sample of afrocolombians from guapi, who are of primarily african ancestry (with some contribution from europeans and native americans), had high frequencies of marginal accessory cusps on both maxillary premolars (delgadoburbano, 2007). marginal accessory cusps contributed to differentiating asian from african and european populations in a study by adams and george (2018) for forensic ancestry estimation. to compare neanderthals to modern humans, small samples representing seven regions were examined by bailey (2002). frequencies of both distal and mesial accessory cusps were moderate to high for both premolars, with mesial cusps exhibiting higher rates of occurrence. no geographic pattern was evident regarding the highest frequencies for tooth or locus in this study; however, the largest sample size for any of these populations was 40 (bailey, 2002). global analyses of dental morphological variation conducted by hanihara (2008) and reyes-centeno et al. (2017) suggest distinct differences between asian populations and african and european populations, though this pattern differs for the third and fourth premolars. however, both studies used the asudas grades, collapsing mesial and distal accessory cusps into a single presence grade, precluding a more nuanced observation. this study provides a comprehensive analysis of the global distribution of the marginal accessory cusps of the maxillary premolars. a secondary objective is to evaluate the utility of distinguishing between locus of expression in population analyses. materials and methods frequencies for marginal accessory cusps of the maxillary third (up3) and fourth (up4) premolars were calculated from the original data sheets of christy g. turner ii on populations around the world (table 1; see scott et al., [2018] for more information on these subdivisions). while the original trait descriptions outlined by asudas do not designate the placement of these cusps, the updated descriptions by scott and irish (2017) distinguish mesial, distal, and mesial + distal expressions. these categories are used to evaluate differences in geographic frequency distributions for each configuration. for those individuals with mesial + distal expressions (grade 3), these were separated into mesial accessory cusp (mac) expression (grade 1) and distal accessory cusp (dac) expression (grade 2) for calculation. chi-square tests were used to identify differences between males and females for each tooth and locus. sex was unknown for many individuals, so only individuals designated as male or female were used to test for sexual dimorphism. all statistical analyses were performed in r studio 1.1.442. results marginal accessory cusps follow the general pattern of most dental morphological traits – little to no sex dimorphism. total frequencies calculated for each population are presented in tables 2a and 2b. only the dat of the fourth premolar in polynesians exhibits statistically significant sexual dimorphism. some populations produced a chi-square value of na when the trait was absent for either males or females. a brief overview is provided for each tooth and locus. up3: mac (table 2a) this trait occurs in low to moderate frequencies around the globe. frequencies range between 0.0% and 35.4% for the pooled sex frequencies, with north africa exhibiting table 1. geographic regions analyzed in the present study. supra-geographic region geographic subdivisions western eurasia eastern europe, north africa, western europe sub-saharan africa west and south africa sahul-pacific australia, new guinea, melanesia sunda-pacific southeast asia (early), southeast asia (recent), polynesia, micronesia sino-americas east asia, northeast siberia, american arctic, northwest coast/ne dene, north america, mesoamerica, south america, jomon/ainu 10 dental anthropology 2019 │ volume 32 │ issue 01 mac dac population male female total p-value male female total p-value west and south africa fr 0.000 0.111 0.023 0.523 0.470 0.176 0.000 0.140 0.669 0.414 n 34 9 43 34 9 43 nubia fr 0.125 0.000 0.077 <0.001 1.000 0.125 0.200 0.154 <0.001 1.000 n 8 5 13 8 5 13 north africa fr 0.000 0.000 0.000 na na 0.000 0.000 0.000 na na n 12 3 15 12 3 15 south asia fr 0.025 0.000 0.019 <0.001 1.000 0.000 0.071 0.019 0.307 0.579 n 40 14 54 40 14 54 western europe fr 0.034 0.016 0.027 0.034 0.853 0.023 0.032 0.027 <0.001 1.000 n 87 63 150 87 63 150 eastern europe fr 0.023 0.066 0.040 1.601 0.206 0.015 0.022 0.018 <0.001 1.000 n 132 91 223 132 91 223 central asia fr 0.086 0.075 0.081 0.024 0.876 0.031 0.045 0.037 0.103 0.748 n 162 134 296 162 134 296 east asia fr 0.359 0.338 0.354 0.231 0.631 0.038 0.033 0.037 0.015 0.902 n 679 210 889 679 210 889 northeast siberia fr 0.152 0.154 0.153 <0.001 1.000 0.030 0.038 0.034 <0.001 1.000 n 33 26 59 33 26 59 american arctic fr 0.174 0.144 0.159 0.341 0.560 0.007 0.006 0.006 <0.001 1.000 n 149 160 309 149 160 309 northwest coast/na dene fr 0.059 0.091 0.077 <0.001 1.000 0.000 0.000 0.000 na na n 17 22 39 17 22 39 north america fr 0.079 0.071 0.075 <0.001 0.987 0.021 0.014 0.018 <0.001 0.994 n 140 141 281 140 141 281 mesoamerica fr 0.041 0.025 0.034 <0.001 1.000 0.000 0.025 0.011 0.010 0.919 n 49 40 89 49 40 89 south america fr 0.075 0.067 0.071 <0.001 0.987 0.037 0.044 0.041 <0.001 1.000 n 134 135 269 134 135 269 jomon/ainu fr 0.234 0.103 0.179 3.766 0.052 0.043 0.000 0.025 1.463 0.227 n 94 68 162 94 68 162 southeast asia (early) fr 0.195 0.043 0.141 1.689 0.194 0.000 0.000 0.000 na na n 41 23 64 41 23 64 southeast asia (recent) fr 0.146 0.145 0.145 <0.001 1.000 0.046 0.048 0.047 <0.001 1.000 n 323 124 447 323 124 447 polynesia fr 0.101 0.120 0.107 0.070 0.791 0.021 0.022 0.021 <0.001 1.000 n 188 92 280 188 92 280 micronesia fr 0.200 0.167 0.191 0.003 0.959 0.092 0.125 0.101 0.003 0.954 n 65 24 89 65 24 89 melanesia fr 0.075 0.075 0.075 <0.001 1.000 0.014 0.015 0.014 <0.001 1.000 n 147 67 214 147 67 214 australia fr 0.04 0.085 0.054 0.561 0.454 0.030 0.021 0.027 0.000 1.000 n 101 47 148 101 47 148 new guinea fr 0.067 0.050 0.062 <0.001 1.000 0.089 0.100 0.092 <0.001 1.000 n 45 20 65 45 20 65 table 2a. frequencies for mac and dac for each population for the third premolar. χ 2 values are present for degree of statistically significant differences between males and females. (fr = frequency, n = number of individuals, * = statistically significant). 11 dental anthropology 2019 │ volume 32 │ issue 01 mac dac population male female total p-value male female total p-value west and south africa fr 0.000 0.250 0.053 0.523 0.470 0.300 0.000 0.237 3.697 0.055 n 30 8 38 30 8 38 nubia fr 0.000 0.000 0.000 na na 0.000 0.400 0.182 0.861 0.354 n 6 5 11 6 5 11 north africa fr 0.000 0.000 0.000 na na 0.000 0.000 0.000 na na n 2 6 8 2 6 8 south asia fr 0.000 0.071 0.018 0.323 0.5696 0.024 0.000 0.018 <0.001 1.000 n 41 14 55 41 14 55 western europe fr 0.033 0.077 0.054 0.361 0.548 0.050 0.038 0.045 <0.001 1.000 n 60 52 112 60 52 112 eastern europe fr 0.033 0.037 0.035 <0.001 1.000 0.056 0.085 0.070 0.218 0.641 n 90 82 172 90 82 172 central asia fr 0.088 0.054 0.071 0.523 0.470 0.053 0.054 0.053 <0.001 1.000 n 114 111 225 114 111 225 east asia fr 0.102 0.059 0.091 2.996 0.083 0.034 0.039 0.035 0.017 0.897 n 649 205 854 649 205 854 northeast siberia fr 0.036 0.053 0.043 <0.001 1.000 0.000 0.000 0.000 na na n 28 19 47 28 19 47 american arctic fr 0.022 0.026 0.024 <0.001 1.000 0.011 0.026 0.020 0.110 0.740 n 92 156 248 92 156 248 northwest coast/ na dene fr 0.000 0.000 0.000 na na 0.000 0.000 0.000 na na n 12 19 31 12 19 31 north america fr 0.033 0.034 0.033 <0.001 1.000 0.044 0.034 0.038 <0.001 1.000 n 91 118 209 91 118 209 mesoamerica fr 0.030 0.000 0.015 <0.001 1.000 0.061 0.030 0.045 <0.001 1.000 n 33 33 66 33 33 66 south america fr 0.053 0.027 0.037 0.296 0.586 0.027 0.045 0.037 0.058 0.809 n 75 112 187 75 112 187 jomon/ainu fr 0.089 0.063 0.077 0.071 0.790 0.000 0.031 0.014 0.750 0.386 n 79 64 143 79 64 143 southeast asia (early) fr 0.074 0.083 0.078 <0.001 1.000 0.074 0.000 0.039 0.407 0.524 n 27 24 51 27 24 51 southeast asia (recent) fr 0.062 0.071 0.064 0.012 0.912 0.079 0.106 0.086 0.468 0.494 n 292 113 405 292 113 405 polynesia fr 0.056 0.082 0.066 0.345 0.557 0.043 0.134 0.077 5.805 0.016* n 162 97 259 162 97 259 micronesia fr 0.190 0.167 0.184 <0.001 1.000 0.159 0.167 0.161 <0.001 1.000 n 63 24 87 63 24 87 melanesia fr 0.075 0.102 0.083 0.119 0.730 0.067 0.102 0.078 0.285 0.594 n 134 59 193 134 59 193 australia fr 0.167 0.120 0.151 0.254 0.614 0.083 0.06 0.075 0.031 0.860 n 96 50 146 96 50 146 new guinea fr 0.182 0.125 0.162 0.069 0.792 0.182 0.083 0.147 0.544 0.461 n 44 24 68 44 24 68 table 2b. frequencies for mac and dac for each population for the fourth premolar. χ 2 values are present for degree of statistically significant differences between males and females. (fr = frequency, n = number of individuals, * = statistically significant). 12 dental anthropology 2019 │ volume 32 │ issue 01 the lowest and east asians the highest prevalence of the trait. a distinct pattern is evident regarding asian and asian-derived populations. east asians have the highest frequency of this trait (35.4%). northeastern siberians (15.3%), american arctic (15.9%), jomon/ ainu (17.9%), southeast asia (early: 14.1%; recent: 14.5%), and micronesia (19.1%) have intermediate frequencies. native american [northwest coast/na dene (7.7%), north america (7.5%), mesoamerica (3.4%), south america (7.1%)] and pacific (polynesia [10.7%], melanesia [7.5%]) groups exhibit the lowest frequencies for asian-derived groups. in general, from the point of highest prevalence in east asia, frequencies decrease into the americas and the pacific. the lowest frequencies of mac on up3 are found in western eurasian (0.0% 4.0%), african (2.3 – 7.7%), and sahul-pacific groups (5.4% 6.2%). up3: dac (table 2a) the distal accessory cusps exhibit a different pattern of geographic variation than the mesial variant on up3. this trait typically occurs in low frequencies, ranging from 0.0% to 15.4%. sub-saharan africans and some pacific island groups display the highest rates. west/ south africa and nubia have the highest frequencies with 14.0% and 15.4%, respectively. although sample sizes are small for this region, this finding may indicate higher frequencies of up3 dac are characteristic of sub-saharan populations. new guinea (9.2%) and micronesia (10.1%) exhibit similar frequencies for the third premolar. other global populations typically have a presence rate of less than 4.0%. north american groups range from 0.0% to 1.8%, while south american groups have a frequency of 4.1%, comparable to central and east asia. melanesian (1.4%), polynesian (2.1%), and australian (2.7%) groups exhibit similar frequencies for dac on the third premolar. western eurasian populations (ranging from 0.0 to 2.7%) are comparable to samples from the americas. up4: mac (table 2b) cusp frequencies on this tooth are significantly lower than on the third premolar, with the highest incidence at 18.4% for micronesians. australians and new guineans have slightly lower frequencies with rates of 15.1% and 16.2%, respectively. melanesians, polynesians, and southeast asians have comparable rates at 8.3%, 6.6%, and 6.4% (recent)/7.8% (early), respectively. these rates are intermediate to sahul-pacific and east asian (9.1%) frequencies. the trait is uncommon in the americas, with frequencies ranging from 0.0% (northwest coast/ne dene) to 3.7% (south america). western european mac frequencies increase from 2.7% on up3 to 5.4% on up4. however, eastern europeans decrease from 4.0% to 3.5%. less variation is present between populations due to uniformly low frequencies; however, there is some clustering of populations who most commonly exhibit this trait. up4: dac (table 2b) while this trait typically occurs in low frequencies, african populations (west and south africa: 23.7%, nubia: 18.2%), along with micronesia (16.1%), and new guinea (14.7%), are exceptions to this trend. melanesian (7.8%), polynesian (7.7%), and australian (7.5%) groups exhibit similar frequencies for the fourth premolar dac. new guinea (14.7%) and micronesia (16.1%) exhibit slightly higher frequencies. north american (3.8%), mesoamerican (4.5%), and south american (4.5%) groups have a higher presence of dat than northern indigenous groups (american arctic: 2.0%, northwest coast/na dene: 0.0%). european dac frequencies increase significantly on up4 compared to up3, increasing from to 2.7% to 4.5% in western europeans and 1.8% to 7.0% in eastern europeans. general regional differences are relatively similar between dac of up3 and dac of up4. discussion marginal accessory cusps of up3 follow a pattern that corresponds to known population histories. most notable is the distribution of this trait among asian-derived populations. east asian groups exhibit the highest frequencies (35.4%). this trait decreases in occurrence in more northern and southern asian populations and in the americas. turner (1971) found a distinction between american arctic and native american groups in the rest of north america, with the former having three -rooted lower first molar frequencies of approximately 27-47% and the latter having a frequency of about 6%. the prevalence of the three-rooted lm1 was used to argue for a three-wave model of migration into the americas: 1) the first being amerinds [north and south american indians], 2) the second being northwest coast groups and na dene speakers, 3) and the third being the ancestors of american arctic groups (turner 1971). here there is a distinction between american arctic populations (15.9%) and north and south american indian groups ranging between 3.4 and 7.7%. the intermediacy of northwest coast/na dene populations found in previous dental morphological and genetic studies (turner 1985; powell 1993; cavalli-sforza et al. 1994; scott and turner 2008) is not present in this study. for marginal premolar cusps, this population has frequencies like native north and south american groups. the variation of mac on up3 also corresponds to the sinodont-sundadont dental complexes defined by 13 dental anthropology 2019 │ volume 32 │ issue 01 turner (1981). the sinodont complex is characterized by the addition of enamel and increased crown complexity, in contrast to the more simplified dental pattern that distinguishes the sundadont complex (turner 1981, 1985). this pattern does not extend to the fourth premolar or to the presence of up3 dac; however, the variation of this trait and its patterned distribution that follows known population history indicates mac of up3 is informative for studies of population affinity. additionally, the mesial accessory cusp reflects the expected intermediacy of central asian populations compared to east asia and western eurasia. this region is intermediate in trait expression for shoveling, enamel extensions, cusp 6, protostylid, three-rooted lm1, and four-cusped lm2 (heim et al., 2016). it has been postulated that this position between these two distinct complexes is a result of gene flow associated with the complex migration histories in the central region of eurasia (heim et al., 2016), rather than a settlement zone for early modern humans when first moving out of africa before expanding into europe and east asia (martínezcruz et al., 2011). this same pattern is not evident for the distal accessory cusp. central asians exhibit higher frequencies of this trait for the third and fourth premolars than both western eurasians and east asians. the lowest frequencies for dac and mac are found in western eurasian populations, particularly in north africa and south asia. north africa is the only group to lack either of these traits on any tooth, though sample size is small. south asia, represented by india, does not exceed 2.0% for either trait on up3 or up4. european populations typically exhibit low frequencies of these traits. this corresponds to the general pattern of simplification of the dental crowns in these populations (scott et al., 2018). the mac frequencies indicate a close relationship between southeast asia, polynesia, and micronesia for the third premolar, but between southeast asia, polynesia, and melanesia for the fourth premolar. additionally, for dac, the closest similarities are between southeast asia, melanesia, polynesia, and australia and between new guinea and micronesia for both premolars. while these are univariate comparisons, it is evident that if taken together, these populations exhibit slight clinal variation from their place of origin in southeast asia. a mean measure of divergence global analysis of 21 crown traits and six root traits also found a greater similarity between polynesians and melanesians than between polynesians and micronesians (scott et al., 2018). the differences between trait and tooth may be reflective of different underlying genetic inheritance patterns and complex migration histories. for instance, while melanesia is typically associated with sahul-pacific groups (scott et al. 2018), melanesia is the origin of the lapita culture that spread into polynesia. it is hypothesized that it is from the area surrounding the santa cruz islands, reef islands, and vanuatu (i.e., “central island melanesia”) where they migrated in multiple waves to remote oceania, producing an indistinct biological, cultural, and linguistic boundary (wollstein, 2010; burley, 2013; skoglund et al., 2016). previous studies of new guinea dentition revealed an unexpected similarity to the european dental complex (scott and turner, 1997; scott and schomberg, 2016). marginal accessory cusps, however, conform to the pattern of expected biological relationships. mesial accessory cusps occur in frequencies most like australians for both the third (a: 5.4%, ng: 6.2%) and fourth (a: 15.1%, ng: 16.2%) premolars. the distal accessory cusps for new guinea are, however, most like micronesian populations for both the third (mic: 10.1%, ng: 9.2%) and fourth (mic: 16.1%, ng: 14.7%) premolars. distal accessory cusps exhibit an interesting pattern where their highest prevalence is in the pacific and sub-saharan africa. african samples are rather small compared to the pacific groups included here, so further data collection is required to substantiate this finding. hanihara (2008) found low frequencies for premolar accessory cusps in a larger sample size of sub-saharan africans; however, different samples and method of analysis (the author combined mesial and distal in a dichotomous presence/absence scale) preclude comparison. in general, the results of the present study are like those of hanihara (2008), with east asians exhibiting the highest frequencies of accessory cusps on the third premolar while micronesian and sahul-pacific populations have the highest frequencies on the fourth premolar. the differences found in the distribution of mac and dac in the same global populations suggest these traits should be separated for biological distance analyses. although dac occurs in lower frequencies than mac, and most populations exhibit uniformly low frequencies, the patterns present suggest genetic drift affected the distribution of this trait. the distribution of mac and its correspondence to known population histories of sinodont and sundadont populations indicate this trait may be included as part of the suite of traits characterizing these dental complexes and may be informative in understanding the migration of populations out of east and southeast asia. 14 dental anthropology 2019 │ volume 32 │ issue 01 previous research has indicated varied rates of intraand interobserver reliability when scoring this trait. various studies have exhibited low replicability between observers and by a single observer (nichol and turner, 1986; griffin, 1989; powell, 1995; aubry, 2009; stojanowski and johnson, 2015; marado et al., 2017). this is likely due, in part, to the absence of a dentine component of these cusps, which results in the obliteration of the trait given a minimal level of wear (turner et al., 1991; scott and irish, 2017). other researchers have found significant levels of intra-observer replicability (hubbard, 2012, thompson, 2013; passalacqua, 2015; maier, 2017). as all individuals included in this analysis were investigated by a single observer (c.g.t. ii) using the scoring system in asudas, inter-observer error is not a concern in this study. turner and colleagues (1991) recommend this trait should not be scored on teeth with significant wear, generally limiting analyses to younger individuals. it is important to remember when scoring accessory cusps that grooves must distinctly separate them from the primary buccal and lingual cusps. if wear precludes the ability to observe these grooves, it is best to not grade the trait. conclusions this study is the first to outline the world variation of mesial and distal accessory cusps on the upper third and fourth premolars. it lays a foundation for better understanding the geographic patterning of this underutilized trait. to a large extent, the variation of these cusps reflects known population histories, particularly regarding the mesial accessory cusp of the upper third premolar. distinctive trends are evident in the distribution of each trait on up3 and up4, indicating their utility in studies of biological relationships. the different geographic patterns between mesial and distal accessory cusps are difficult to explain but may suggest the traits experienced different evolutionary histories. as a result, these traits should be treated separately in biodistance statistics rather than collapsed into a scale that tallies mesial and distal cusps together. acknowledgments the authors acknowledge the extraordinary efforts of the late christy g. turner ii who collected dental morphological data on 23,000 individuals around the world. although no longer with us, his legacy lives on. references adams, d. m., & george r. l. (2018). fuzzy inference systems (fis) as a novel approach to forensic ancestry estimation. proceedings of the american academy of forensic sciences. seattle, washington. aubry, b. s. (2009). population structure and interregional interaction in pre-hispanic mesoamerica: a biodistance study. [ph.d. dissertation.] columbus, oh: the ohio state university. bailey, s. e. (2002). neanderthal dental morphology: implications for modern human origins. (doctoral dissertation). tempe, az: arizona state university. bailey, s. e., & hublin, j.-j. (2006). dental remains from the grotte du renne at arcy-sur-cure (yonne). journal of human evolution, 50, 485-508. benazzi, s., viola, b., kullmer, o., fiorenza, l., harvati, k., paul, t., gruppioni, g., weber, g. w., & mallegni, f. (2011). a reassessment of the neanderthal teeth from taddeo cave (southern italy). journal of human evolution, 61, 377-387. burley, d. v. 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(2017). the combination of cranial morphoscophic and dental morphological methods to improve the forensic estimation of ancestry. [ph.d. dissertation]. reno, nv: university of nevada, reno. martínez-cruz, b., vitalis, r., ségurel, l., austerlitz, f., georges, m., théry, s., quintana-murci, l., hegay, t., aldashev, a., nasyrova, f., & heyer, e. (2011). in the heartland of eurasia: the multilocus genetic landscape of central asian populations. european journal of human genetics, 19, 216223. martinón-torres, m., bermúdez de castro, j. m., gómez-robles, a., margvelashvili, a, prado, l, lordkipanidze, d., & vekua, a. (2008). dental remains from dmanisi (republic of georgia): morphological analysis and comparative study. journal of human evolution, 55, 249-273. morado, l. m., silva, a. m., & irish, j. d. (2017). fluctuating asymmetry in dental and mandibular nonmetric traits as evidence for childcare sex bias in 19th/20th century portugal. homo – journal of comparative human biology, 68, 18-29. nichol, c. r., & turner, ii, c. g. (1986). intraand interobserver concordance in classifying dental morphology. american journal of physical anthropology, 69, 299-315. passalacqua, k. z. (2015). an investigation of late woodland and mississippian biological relationships using odontometric and dental non-metric trait analyses. [ph.d. dissertation]. bloomington, in: indiana university. powell, j. f. (1993). dental evidence for the peopling of the new world: some methodological considerations. human biology, 65, 799-815. powell, j. f. (1995). dental variation and biological affinity among middle holocene human populations in north america. [ph.d. dissertation]. college station, tx: texas a&m university. reyes-centeno, h., rathmann, h., hanihara, t., harvati, k. (2017). testing modern human outof-africa dispersal models using dental nonmetric data. current anthropology, 58, s406-s417. skoglund, p., posth, c., sirak, k., spriggs, m., valentin, f., bedford, s., clark, g. r., reepmeyer, c., petchey, f., fernandes, d., fu, q., harney, e., lipson, m., mallick, s., novak, m., rohland, n., stewardson, k., abdullah, s., cox, m. p., friedlaender, f. r., friedlaender, j. s., kivisild, t., koki, g., kusuma, p., merriwether, d. a., ricaut, f-x., wee, j. t. s., patterson, n., krause, j., pinhasi, r., & reich, d. (2016). genomic insights into the peopling of the southwest pacific. nature, 538, 510-513. scott, g. r., & irish j. d. (2017). tooth crown and root morphology: the arizona state university dental anthropology system. cambridge: cambridge university press. scott, g. r., & schomberg, r. (2016). a baffling convergence: tooth crown and root traits in europe and new guinea. in: m. a. pilloud & j. t. hefner (eds.), biological distance analysis: forensic and bioarchaeological perspectives. (pp. 411-424). amsterdam: academic press. scott, g. r., & turner, c. g., ii. (1997). the anthropology of modern human teeth: dental morphology and its variation in recent human populations. cambridge: cambridge university press. scott, g. r., & turner, c. g., ii. (2008). the physical anthropological intermediacy problem of nadené/greater northwest coast indians. alaska journal of anthropology, 6, 57-68. scott, g. r., turner, c. g., townsend, g. c., & martinón-torres m. (2018). the anthropology of modern human teeth: dental morphology and its variation in recent and fossil homo sapiens. cambridge: cambridge university press. stojanowski, c. m., & johnson, k. m. (2015). observer error, dental wear, and the inference of new world sundadonty. american journal of physical anthropology, 156, 349-362. thompson, a. r. (2013). an analysis of biological variation during the late woodland-mississippian period in the midwest using the dentition. [ph.d. dissertation] bloomington, in: indiana university. turner, c. g. (1971). three-rooted mandibular first permanent molars and the question of american indian origins. american journal of physical anthropology, 34, 229-241. turner, c. g. (1985). dental evidence for the peopling of the americas. national geographic society research reports, 19, 573-596. turner, c. g. (1987). late pleistocene and holocene population history of east asia based on dental variation. american journal of physical anthropology, 73, 305-321. turner, c. g., nichol, c. r., & scott, g. r. (1991). scoring procedures for key morphological traits of the permanent dentition: the arizona state university dental anthropology system. in m. a. kelley & c. s. larsen. (eds.), advances in dental anthropology. (pp. 13-31). new york: wiley-liss. wollstein, a., lao, o., becker, c., brauer, s., trent, r. j., nürnberg, p., stoneking, m., & kayser, m. (2010). demographic history of oceania inferred from genome-wide data. current biology, 20, 1983-1992. nelson 2010.3 79 although probably occurring in frequencies similar to those found in modern clinical samples, eruption disturbances are rarely reported from archaeologically derived skeletal series. several factors lead to this underreporting including lack of recognition by workers unfamiliar with dental anatomy and eruptive processes and the associated fact that low natural occurrence frequencies lead to extreme rarity in the often small population samples anthropologists commonly study. in addition, when eruptive disturbances are found they frequently appear in a single individual so have little evolutionary or predictive value. however, when two eruption disturbances, affecting both mandible and maxilla and different tooth classes, appear in a single individual further investigation and reporting is warranted, particularly when one is considered quite rare by clinical standards. in this short communication i explore a case of lower first molar impaction in an individual from the ancestral puebloan gallina phase of north central new mexico dating to approximately 750 years ago. this individual also expresses labial ectopic alveolar eruption of the left maxillary canine. according to pindborg (1970) and andreasen et al. (1997) impaction of the lower first molar is the rarest of eruptive disturbances with occurrence frequencies reported to be between 0.00 and 0.063 percent (dachi and howell, 1961; kramer and williams, 1970; shah et al., 1978; grover and lorton, 1985). because of its rarity, documentation and description of lm1 impaction in an individual from a prehistoric context may shed some light on the etiology of the anomaly and its developmental background. in contrast to m 1 impaction, ectopic eruption of maxillary canines is relatively common at least among positional developmental anomalies. the maxillary canine is one of the most frequently malerupted teeth and palatal and labial ectopic eruption is well documented (pindborg, 1970; peck et al., 1994; becker and chaushu, 2000; chaushu et al., 2003; camilleri et al., 2008). in addition, transposition of maxillary canines and third premolars is one of the best documented dental anomalies among prehistoric skeletal series (nelson, 1992; burnett and weets, 2001). context of the burial the gallina were an ancestral pueblo group who occupied a fairly restricted geographic area of northern new mexico during the pueblo iii period (approximately 1100-1300 ad). centered in the llaves valley the gallina were maize horticulturalists who were greatly impacted by extended droughts of the thirteenth century and who disappear between 1260 and 1300 ad (ellis, 1988; crown et al., 1996). the bmg site is an unexcavated habitation site occupying a small ridge on the western flanks of the llaves valley that was surveyed during summer 2006. during this survey a skeleton was discovered eroding out just west of the ridge top and collected. the individual, bmg-1, is a female of approximately 19-23 years of age based on dental wear and tooth eruption and iliac crest impacted lower first molar and labial ectopic upper canine eruption in an individual from the prehistoric american southwest greg c. nelson department of anthropology, university of oregon, eugene, oregon 97403-1218 correspondence to: greg c. nelson, department of anthropology, university of oregon, eugene, oregon 97403-1218 e-mail: gcnelson@uoregon.edu abstract tooth impactions and other positional anomalies are commonly encountered in clinical situations but are much less frequently seen in, or reported from, prehistoric archaeologically derived contexts. this report examines the occurrence of two positional anomalies, lower first molar impaction and upper canine labial ectopic eruption, in a single individual from the ancestral pueblo gallina phase (1100-1275 ad) of northern new mexico. although outwardly dissimilar, appearing as they do in different tooth classes and both the mandible and maxilla, their underlying similarity implies a common etiology. the co-occurrence of these anomalies presents an opportunity to explore the etiological basis of positional anomalies and possibly provide some insight into the very early stages of dental morphogenesis. dental anthropology 23(3):79-82. 80 g.c. nelson fusion (buikstra and ubelaker, 1994; bass, 1995). upon curation and cleaning in the lab four skeletal elements representing a neonate were discovered (bmg-1a). description of gnathic elements dental and gnathic remains of bmg-1 include most of the mandible, the left maxilla, and three isolated maxillary teeth. the mandibular corpus (fig. 1) is broken in the right premolar area such that the posterior portion of the right corpus does not connect with the remainder of the mandible although both rp 3 and rp 4 are present. the anterior portion of the rp 3 socket remains allowing correct placement of this tooth within the arcade. all teeth are present except for lm 3 , rm 2 , and rm 3 . the sockets fig. 1. mandible of bmg-1. (a) superior view of mandible and dental arcade with impacted rm 1 . note wear differential between lm 1 and rm 1 . rp 4 was recovered but destruction of corpus precludes reattachment. (b)lateral view of right corpus with rm 1 exposed. it can be seen in this lateral view that the occlusal surface of rm 1 is at the level of he alveolus even though the roots are fully formed. scale in cm. fig. 2. left maxilla of bmg-1. (a) lateral view. (b) anterior view. (c) superior view, arrow points to canine root in floor of nasal cavity. scale in cm. 81lower first molar impaction of the missing molars are complete and there is a distal interproximal facet on lm 2 indicating the third molars had fully erupted. both rami are missing and the lateral outer table of the posterior right corpus has broken away revealing the cancellous bone. the alveolar portion of the left maxilla (fig. 2) is complete and retains the ectopically erupting lc and the lm1 and lm2. the lp3 is loose but fits into its partial socket while li1, li2, lp4, and lm3 are missing but were lost postmortem. the only remains of the right maxilla are the ri2, rc, and rp3. wear is moderate with dentine exposure on the lower incisors and dentine patches on the major cusps of the lm 1 (fig. 1a). although extreme by modern standards for an individual of this age, advanced wear is common for prehistoric maize horticulturalists whose teeth were greatly impacted by grinding stone grit. the wear pattern for this individual is typical except for the almost complete lack of wear on the lp 3 and lp 4 which reflects the noneruption of the maxillary left canine and the corresponding gap in the maxillary arcade. lower right first molar impaction. the breakage of the posterior right mandibular corpus, although unfortunate as far as integrity of the remains is concerned, does allow visualization of the entire impacted right first molar (fig. 1b). the tooth lies approximately 20˚ off the vertical and appears to have been impacted against the rp4 although there are no contact facets on the distal root or crown of this tooth. because of the position of the tooth within the corpus, the crown level with the alveolar border and the fact that there is no polish on the cusps, the tooth was probably never continually exposed to the oral environment. although the corpus mesial to rm 1 and distal to rp 3 is broken and missing, both premolars appear to have erupted normally indicating that rdm 2 was not retained, as can be common in m 1 impactions (bjerklin and kurol, 1983). the distal border of the rm 1 socket exhibits some remodeling indicating that although the m1 had not erupted periodontal disease was causing minor resorptive bone loss. upper left canine ectopic eruption. the canine is erupting through the alveolus between the roots of the li2 and lp3 and is oriented perpendicular to the tooth row with the root appearing in the floor of the left nasal cavity (fig. 2c). the sockets for the li1 and li2 are normal in form and position while the lp3 is rotated approximately 30˚ distally. there is a gap between the li2 and lp3 indicating that space was available for the lc had it been properly oriented (fig. 2a, b). additionally, the alveolus between the li2 and lp3 is retained and shows no indication of dlc retention. discussion the appearance of anomalies of dental development and eruption in prehistoric skeletal series allows us to examine their occurrence outside of a clinical setting and can provide insight into their etiology and development. although an in-depth examination of the ultimate cause of these anomalies is beyond the scope of this investigation an exploration into the occurrence of two anomalies in one individual might lend some insight into the developmental processes and genetic underpinnings of dental morphogenesis. although prior research into cooccurrence shows little or no correspondence between ectopic canine eruption and m1 impaction (baccetti, 1998, 2000) the possibility that similar genetic or developmental pathways lead to these positional anomalies is intriguing. with bmg-1 we are presented with two instances of positional anomalies that do not appear to have been caused by common environmental perturbations such as retention of deciduous teeth or crowding. in both cases the original orientation of the tooth bud seems to have been rotated from its normal position causing the tooth to grow in the wrong direction. these cases of anomalous placement within the gnathic elements indicate disruption of the developmental pathway very early in embryogenesis possibly at the placode stage or even earlier when the cells that are to become the tooth bud are first differentiating (thesleff, 2000, 2003). this implies that along the ectoderm/mesenchyme boundary at the point of contact between the signaling molecules (such as shh) and their receptors and target genes there is a malfunction in the mechanism which orients the tooth in space. whether the anomalous orientation is due to a breakdown in the cellular matrix and tissue structure or in the genetic signaling is unknown. one clue may be found in the observation that although within the dental arcade the axes of misorientation are different, labiolingual for the canine and mesio-distal for the molar, in space the axes are the same, i.e. antero-posterior with the crown directed anteriorly. this similarity in orientation in space may offer insight both into which element within the developmental genetic cascade involved in tooth formation misfires and whether these molar and canine positional anomalies are related etiologically. if the misorientation of the two teeth is etiologically related then the failure could be due to several factors including, (1) a misalignment of the target cells within either the epithelial or mesenchymal tissue, depending on when in the genetic cascade it occurs (2) misorientation of the placode upon initial budding to the mesenchyme and (3) a kink in the epithelial/mesenchyme tissue complex within the already developing maxilla and mandible. it is also important to note that the crowns and roots of both teeth are normal, with cusps in the proper form and location, indicating no disruption of genetic communication after the initial budding of the placode to the mesenchyme or in the actual development of the tooth. for the time being many questions concerning the ultimate cause of these positional anomalies must remain unanswered. however, insights gained from 82 the case of bmg-1 may allow the focus to be narrowed down to a small developmental window early in tooth morphogenesis during the period at or before the placode buds to the mesenchyme. because of the large number of signaling and target genes involved in the genetic cascade responsible for the earliest stages of dental development it may be difficult to pinpoint exactly which combination results in locating the developing tooth in space. acknowledgements the author would like to thank tony largaespada and mike bremer of the santa fe national forest as they were instrumental in all phases of our research in new mexico. literatur cited andreason jo, petersen jk, laskin dm, editors. 1997. textbook and color atlas of tooth impactions. st. louis: cv mosby. baccetti t. 1998. a controlled study of associated dental anomalies. angle orthod 68:267-74. baccetti t. 2000. tooth anomalies associated with failure of eruption of first and second permanent molars. am j orthod dentofacial orthop 118:608-610. bass wm. 1995. human osteology: a laboratory and field manual, 4th edition. columbia, mo.: missouri archaeological society. becker a, chaushu s. 2000. dental age in maxillary canine ectopia. am j orthod dentofacial orthop 117:657-662. bjerklin k, kurol j. 1983 ectopic eruption of the maxillary first permanent molar: etiological factors. am j orthod 84:147-155. buikstra je, ubelaker dh. 1994. standards for data collection from human skeletal remains. fayetteville, arkansas: arkansas archaeological survey research series no. 44. burnett se, weets jd. 2001. maxillary canine-first premolar transposition in two native american skeletal samples from new mexico. am j phys anthropol 116:45-50. camilleri s, lewis cm, mcdonald f. 2008. ectopic maxillary canines: segregation analysis and a twin study. j dent res 87:580-583. chaushu s, sharabi s, becker a. 2003. tooth size in dentitions with buccal canine ectopia. eur j orthod 25:485-491. crown pl, orcutt jd, kohler ta. 1996. pueblo cultures in transition: the northern rio grande. in: adler ma editor. the prehistoric pueblo world, a.d. 1150-1350. tucson: university of arizona press, p 188-204. dachi sf, howell fv. 1961. a survey of 3,874 routine full mouth radiographs. ii. a study of impacted teeth. oral surg 14:1165-1169. ellis fh. 1988. from drought to drought: an archaeological record of life patterns as developed by the gallina indians of north central new mexico (a.d. 10501300). santa fe: sunstone press, 1988. grover ps, lorton l. 1985. the incidence of unerupted permanent teeth and related clinical cases. oral surg oral med oral pathol 59:420-425. kramer rm, williams ac. 1970. the incidence of impacted teeth. oral surg oral med oral pathol 29:237-241. nelson gc. 1992. maxillary canine/third premolar transposition in a prehistoric population from santa cruz island, california. am j phys anthropol 88:135144. pindborg jj. 1970 .pathology of the dental hard tissues. philadelphia: wb saunders, 1970. peck s, peck l, kataja m. 1994. the palatally displaced canine as a dental anomaly of genetic origin. angle orthod 64:249-256. shah rm, boyd ma, vakil tf. 1978. studies of permanent tooth anomalies in 7,886 canadian individuals. j canad dent assn 44:262-264. thesleff i. 2000. genetic basis of tooth development and dental defects. acta odontol scand 58:191-194. thesleff i. 2003. developmental biology and building a tooth. quintessence int 34:613-620. g.c. nelson 17 dental anthropology 2020 │ volume 33 │ issue 01 dental molding compounds and casts: use in non-laboratory environments rebecca k. scopa kelso 1* , brannon i. hulsey 2 , and kathryn r.d. driscoll 3,4 1 department of biomedical sciences, west virginia school of osteopathic medicine, lewisburg, wv 2 department of anthropology, university of tennessee, knoxville, tn 3 heartland community college, normal, il 4 illinois state university, normal, il adequately documenting archaeological and paleontological dental remains in the field can be a problem when the dentition cannot be removed from their archaeological site, museum collection, or country of origin. macroscopic analysis, such as enamel hypoplasia and microwear studies, rely on visual inspection of the dentition. instead of relying solely on notes, sketches, and photographs, it is ideal to make replicas of the teeth that could then be taken home for further analysis such as studies on microwear and dental enamel hypoplasia (egocheaga, 2004; mihlbachle, foy, & beatty, 2018; stynder et al., 2018; ungar, livengood, & crittenden., 2019; ungar & m’kiera, 2013; ungar & williamson, 2000). the process of making an accurate replica of a tooth requires using a molding compound to create a mold and then the use of either an epoxy or stone casting material filling the mold, to produces an accurate cast. in order to produce casts with exactly the same dimensions as the original tooth, the guidelines provided with the molding and casting compounds should be followed precisely. while many field research opportunities require one to be away from climate-controlled workspaces for weeks or months at a time, most molding compounds require casts to be made from their products within one week of forming the mold. often times archaeological or paleontological dental remains are not allowed to leave their country of origin, compelling an alternate method for research to continue after returning to one’s home location. field research can last from only a few days to a few months, which could make following the material guidelines problematic in many field research settings. additionally, it is recommended that the molding compound and subsequently created molds be kept at room temperature (~72˚f) (coltène whaledent, 2018), which is not always attainable for extended periods in field abstract dental casts are invaluable research tools. there are a variety of molding compounds available, all having temperature, humidity, and timing guidelines to ensure a precise replica of dentition. however, not all field research conditions allow for adherence to environmental guidelines requiring longer wait times prior to pouring epoxy for casting. this study tests a common molding compound in non-controlled environments and over varying time intervals, testing the integrity of the dental molds in producing precise replicas of original teeth. five hundred and eight molds were created under three varying environments: room temperature, hot/humid, and cold/dry. molds were removed from these environments in two-week intervals over twelve weeks. the resulting casts were measured to determine timing limitations for producing accurate dental casts under varying environments. molds stored at room temperature retained their shape and size for the complete twelve weeks. molds kept in a hot and humid environment, however, only maintained their shape and size up to four weeks, whereas molds in a cold and dry environment showed significant changes by the end of the second week. these findings provide additional tools for researchers working in a variety of field conditions allowing casts to be taken of specimens that cannot be transported off site. *correspondence to: rebecca scopa kelso department of biomedical sciences west virginia school of osteopathic medicine rscopkelso@osteo.wvsom.edu keywords: dental casts, dental morphometrics, molding compound 18 dental anthropology 2020 │ volume 33 │ issue 01 research conditions. in many cases, making dental molds to transport back to one’s home research location is more advantageous than making the molds and casts in the field for several reasons. if the field research location is in a remote area flying with casting material can be difficult. the excessive physical weight of dental stone before and after it has been cast can be a limiting factor for air travel and shipping, as well as its relative fragile nature once cast. additionally, 2-part epoxy components contain both a class 8 corrosive liquid and a class 9 hazardous material. flying with these components is against the federal aviation administration regulations and shipping can be problematic, requiring special labeling and specific delivery locations. therefore, traveling with the lighter inert components of the molding compounds would be advantageous. however, is it still a viable option to use these molding compounds when research conditions are less than ideal? what happens when field sites are in more extreme environmental conditions and research facilities have little or no environmental controls, requiring molding compounds and molds to be used and stored outside the material temperature and humidity guidelines? to determine the range of conditions under which the integrity of the molds can be maintained, we tested a commonly used molding compound, president putty soft (grine & kay, 1987; mahoney, 2006; nystrom, phillips-conroy, & jolly, 2004; teaford & oyen, 1989; ungar, 1996), in a variety of environments for varying lengths of time. molds were made and placed in three environments chosen to imitate potential field conditions: room temperature, hot /humid, and cold/dry. molds were removed for epoxy casting in two-week intervals to determine if and when the molds become compromised and cast dimensions deemed unreliable. materials and methods for this study, the commonly used molding compound presidential putty soft (coltène-whaledent, 2018) (figure 1) was tested for its ability to maintain integrity over time in differing environments. disposable paraffin embedding molds were used in two sizes to contain the molding material throughout the project, rectangular 22mm x 40mm x 20mm deep held two tooth impressions and 22mm x 22mm square x 20mm deep held one tooth impression (polysciences, 2019). twelve maxillary premolars were used to make 49 impressions each for a total of 588 tooth molds within a two-hour time frame (figure 2). the molds were then equally divided into groups of 196 and placed in three separate environments: room temperature, hot/humid and cold/dry. after removal from the test environments epotek 301 (epoxy technologies, 2019) was poured into each mold to form a cast of the individual tooth. epoxy was chosen over a dental stone casting material like gypsum due to its durability and common use in the field (egocheaga, 2004; mihlbachle, foy, & beatty, 2018; stynder et al. 2018; ungar livengood, & crittenden, 2019; ungar & m’kiera, 2013; ungar & williamson, 2000). three artificial environments were constructed to simulate nonenvironmentally controlled environmental field conditions. the first set of 196 molds was placed in a typical indoor climate controlled environment with the environmental controls set to 72° fahrenheit and a relative humidity (rh) of approximately 50% (ashrae, 2017). the second environment was designed to simulate figure 1. molding compound figure 2. dental mold 19 dental anthropology 2020 │ volume 33 │ issue 01 field conditions in places like the highlands of peru, the alps, and siberia, so a set of 196 molds was placed in a refrigerator with a drying agent, a 10oz container of calcium chlorite moisture absorber, mimicking the effects of a cold and dry environment; the average temperature was 32°f with a variance with a rh of approximately 33% (figure 3). the final set of 196 molds was placed in an insulated aquarium with a heat source, a reptile under tank heater, set to 95°f and kept the bottom of the tank covered with water between a ¼ of an inch to 1 inch of water to attain an average temperature of 95°f and an approximate rh of 99% (figure 4). this hot and humid test environment was designed to replicate field conditions found in central america, southeast asia, and parts of oceania. air temperature and relative humidity were monitored in each environment by placing hobo automatic data logger sensors placed directly beside the molds throughout the entirety of the study. each of the three sensors was set to record the air temperature and relative humidity of the study environment every 6 hours to ensure that conditions were maintained. table 1 provides the summary data for the three test environments. the hobos showed that the temperature in the in “room temperature” test environment averaged 70.5°f with a maximum temp of 78°f and a minimum of 65.6°f and a relative humidity averaging 43.1% with a maximum of 58.7% and a minimum of 37.1% relative humidity. the hobo readings from within the “cold and dry” environment showed that the average temperature was 32°f with a maximum of 34.9°f and a minimum of 30.1°f. the relative humidity in the “cold and dry” test environment averaged 31.1% with a maximum of 45.2% and a minimum of 23.9% relative humidity. the “hot and humid” environment’s average temperature was 94.2°f with a maximum of 99.1°f and a minimum of 88.3° f. the “hot and humid” test environment relative humidity average was 95% with a maximum of 98.6% and a minimum of 87.2% according to the environmental hobo. assuming an average summer field season of three months, twelve weeks was used as our total experimental period. according to the president putty soft instructions for use (2018) casting matetest environment average temperature (°f) temperature maximum (°f) temperature minimum (°f) average % relative humidity % relative humidity maximum % relative humidity minimum room temp 70.5 78 65.59 31.1 45.2 23.9 cold/dry 32 34.9 30.1 43.1 58.7 37.1 hot/humid 94.2 99.1 88.3 95.3 98.6 87.2 table 1. environmental test conditions figure 3. cold dry environment figure 4. hot humid environment 20 dental anthropology 2020 │ volume 33 │ issue 01 rial can be poured into the molds as soon as thirty minutes after they are made and should remain dimensionally stable for up to 7 days. within twelve hours of making the molds, epo-tek 301 (epoxy technology, inc., billerica, ma) epoxy was poured into twenty-eight molds left at room temperature to form the control tooth casts. in twoweek increments twenty-eight molds were removed from each of the three test environments. the molds were given twelve hours to return to room temperature before casts were poured using epo-tek 301 two-part epoxy. returning the molds to room temperature was designed to simulate returning to a climate controlled research environment to pour the casting material. the epo-tek 301 requires approximately 24 hours to harden at which point the casts were removed from the molds for measuring (figure 5). due to stretching and damage sustained while removing the dental casts, none of the removed and casted molds were returned to their test environments. a new set of 28 molds were removed for each subsequent twoweek casting. bucco-lingual length, mesio-distal length, and crown height are standard dental measurements used in a variety of research methodologies (buikstra & ubelaker, 1994). due to the relatively small size of teeth, a slight variation in these measurements can create statistical significance and therefore it is imperative that the casted replicas be a completely accurate representation of the original tooth. therefore, these three measurements were used as markers of any meaningful change in the shape or size of the molds. the bucco-lingual length, mesio-distal length, and crown height of each dental cast was measured using digital calipers consistently by only one of the authors (rsk) to control for inter-observer error. measurements were repeated for each dental cast in one-week time intervals for a total of three sets of repeat measurements to establish intra-observed reliability with analysis of variance. the observer was blind to the previously recorded measurements and environmental treatment of each casts. results of repeated measures anova to test for the intraclass correlation coefficients for the three repeated measurements of bucco-lingual length, mesiodistal length, and crown height per tooth were all above 0.90 and therefore considered highly consistent. the three repeated measurements were then averaged together to provide an averaged bucco-lingual length, mesio-distal length, and crown height for each tooth and used to determine if the size of the molds in each environment changed over time. because the data were not normally distributed, wilcoxon signed-rank tests were used to test for significant differences between time intervals in each environment. results table 2 provides summary statistics comparing cast measurements among environmental conditions. those weeks that differed significantly from the null hypothesis are noted. the number (n) listed in the table refers to only those teeth (with all bucco-lingual diameter, mesio-distal diameter, and crown height measurements) used in that twoweek test sample. for example, in “room temperature,” 28 teeth with three measurements were used providing 84 compared measurements. when successive weeks were significantly smaller, this indicates that the molds and resulting casts were “shrunken” versions of the initial molds and original teeth. significant increases in measurements in later weeks indicate that the molds and resulting casts were “swollen” versions of the originals. as shown in the table, the room temperature molds showed no significant changes throughout the entire twelve-week period. this was an expected result; when the molding compound was used as directed, it maintained its integrity. however, this was not the case once the conditions were altered. the hot/humid molds remained stable until the fourth week, whereupon the cast measurements became significantly larger due to the swelling of the molds than cast made at week 0. this swelling manifested as an increase in the molds in two of the three dimensions, increasing the space left by the dental impression. the statistically significant figure 5. epoxy casts 21 dental anthropology 2020 │ volume 33 │ issue 01 change occurred in the fourth week with an increase in the mesio-distal and crown height measurements of the casts. bucco-lingual changes manifest as a shrinking of the cast and became significantly different from the initial week 0 cast at the sixth-week mark. even though the wilcoxon signed-rank tests did not show significant differences between successive weeks compared to the initial week 0 casts until week twelve, additive changes between weeks two and four, as well as weeks 2 and 8 were also significant. the cold/dry molds showed significant changes by week two in the bucco-lingual direction. all three cast measurements became significantly smaller due to the shrinkage of the casts. this shrinking manifested as a decrease in the overall size of the molds, including the space left by the dental impression. wilcoxon signed-rank tests between the successive weeks indicated no additional significant differences; however, by week ten, the additive changes between weeks four and ten and weeks four and twelve became significantly different. discussion and conclusions this study has shown that researchers have adequate time to produce dental molds over the course of a field season and return home to pour the epoxy for casts, producing reliable tooth replicas, if the molds can be kept in an environmentally controlled setting (~72°f and 50% rh). however, molds kept in a relatively cold and dry environment (~39°f and 33% rh) have been shown to shrink significantly within a short period of time (< two weeks). therefore, molding dental remains would not be appropriate for these field conditions, as the casts would not produce reliable measurements. using this molding product in a hot and humid environment (~95°f and 99% rh) for a short period of time would be feasible, because molds appear to remain stable for four weeks. making dental molds to transport back to one’s home research location is more advantageous than making the molds and casts in the field for several reasons. if the field research location is in a remote area flying with casting material can be difficult. the excessive physical weight of dental stone before and after it has been cast can be a limiting factor for air travel and shipping, as well as its relative fragile nature once cast. additionally, 2-part epoxy components contains both a class 8 corrosive liquid and a class 9 hazardous material. flying with these components is not allowed and shipping can be problematic, requiring special labeling and delivery locations. considering these factors, the ability to travel with only the molding compounds greatly improves the ease and likelihood of future dental analysis from dental casts. in summary, researchers can reliably utilize president putty soft as a tool for recording dental information from teeth even in a variety of environmental conditions up to a certain period of time. this method will prove especially useful test environment number of tooth measurements used in comparison change (δ) in cast measurements from the control group (week 0) p value overall resulting change in casts room temperature 84 week 0 vs. weeks 2-12 = δ 0.576 (average) no change 82 week 0 vs. weeks 2-10 = δ 0.254 (average) no change hot/humid week 0 vs. week 12 = δ 0.006* swelling week 0 vs. week 4 (crown height) = δ .026* swelling week 0 vs. week 4 (mesiodistal) = δ 0.05* swelling week 0 vs. week 6 (bucolingual) = δ .003* shrinkage week 2 vs. week 4 = δ 0.006* swelling week 2 vs. week 8 = δ 0.001* swelling cold/dry 79 week 0 vs. weeks 2-12 = δ 0.006*(average) shrinkage week 4 > week 12 0.003* table 2. study results timing of cast changes between test environments 22 dental anthropology 2020 │ volume 33 │ issue 01 when specimens cannot be removed from the archaeological site, museum collection, or country of origin for further analysis. acknowledgements we would like to thank robert geller, d.m.d. at coltène whaledent and joe mccabe at epoxy technology for their more than gracious donation of putty and epoxy. we would also like to thank drs. richard m. kelso, richard a. kelso, and robert m. kelso for their assistance on this project. references ashrae (2017). thermal environmental conditions for human occupancy. ansi/ashrae addendum b to ansi/ashrae standard 55-2013. atlanta, georgia. www.ashrae.org. buikstra, j. e., & ubelaker, d. h. (eds.). (1994). standards for data collection from human skeletal remains. proceedings of a seminar at the field museum of natural history organized by jonathan haas (vol. 44). fayetteville: arkansas archaeological survey. coltène whaledent a. g. (2018) president putty soft instructions for use. altstätten: switzerland. www.coltenewhaledent. com. egocheaga, j., pérez-pérez, a., rodríguez, l., galbany, j., martínez, l., & antunes, m. (2004). new evidence and interpretation of subvertical grooves in neanderthal teeth from cueva de sidrón (spain) and figueira brava (portugal). anthropologie, 42(1), 49-52. epoxy technology. (2019) epo-tek 301 instructions for use. billerica, ma. www.epotek.com fiorenza, l., benazzi, s, & kullmer, o. (2009). morphology, wear and 3d digital surface models: materials and techniques to create highresolution replicas of teeth. journal of anthropological sciences, 87, 211-218. grine, f.e. & kay, r.f. (1987). quantitative analysis of occlusal microwear in australopithecus and paranthropus. scanning microscopy, 1, 647 -656. mahoney, p. (2006). dental microwear from natufian hunter-gatherers and early neolithic farmers: comparisons within and between samples. american journal of physical anthropology, 130, 308–319. mihlbachler, m.c., foy, m., & beatty, b.l. (2019). surface replication, fidelity and data loss in traditional dental microwear and dental microwear texture analysis. scientific reports, 9 (1), 1595. nystrom, p., phillips-conroy, j. e. & jolly, c. j. (2004). dental microwear in anubis and hybrid baboons (papio hamadryas, sensu lato) living in awash national park, ethiopia. american journal of physical anthropology, 125, 279–291. polysciences. (2019) peel-a-way embedding mold. warrington, pa. http:// www.polysciences.com stynder, d.d., desantis, l.r. g., donohue, s.l., schubert, b.w., & ungar, p.s. (2018). a dental microwear texture analysis of the early pliocene african ursid agriotherium africanum (mammalia, carnivora, ursidae). journal of mammalian evolution, doi 10.1007/s10914-018 -9436-y. teaford, m. f. and oyen, o. j. (1989). live primates and dental replication: new problems and new techniques. american journal of physical anthropology, 80, 73–81. ungar, p.s. (1996). dental microwear of european miocene catarrhines: evidence for diets and tooth use. journal of human evolution, 31(4), 335-366. ungar, p.s., livengood, s.v., & crittenden, a.n. (2019). dental microwear of living hadza foragers. american journal of physical anthropology, 169(2), 356-367. ungar, p.s., & m’kirera, francis. (2003). a solution to the worn tooth conundrum in primate functional anatomy. proceedings of the national academy of sciences, 100(7), 3874. ungar, p. & williamson, m. (1999). exploring the effects of tooth wear on functional morphology: a preliminary study using dental topographic analysis. palaeontologia electronica, 3, 1 -18 bonakdarchian and ghorbanipour 2010.3 53 one of the confusing and difficult aspects of complete denture prosthodontics is the selection of appropriately sized maxillary anterior denture teeth (hoffman et al., 1986). the anterior teeth are primarily selected to satisfy esthetic concerns. the esthetic restoration of edentulous patients has an important psychological effect (sellen et al., 1999; al-wazzan, 2001; frush and fisher, 1955). patients who receive their dentures expect them to appear similar to their previous natural teeth (gomes et al., 2009). the mesiodistal width of teeth is a harder aspect to estimate than the proper height of the anterior artificial teeth (mcarthur, 1985). various guidelines have been suggested for determining the maxillary anterior teeth when preextraction records are not available, but different opinions have been reported regarding their usefulness (sellen et al., 1999; verjao and nogueira, 2005). one of the methods for selecting artificial anterior teeth is using certain guides (keng, 1960). several anatomic measurements have been suggested, including bizygomatic width (bzw), interpupillary distance (ipd), interalar width (iaw), and intercommisural width (icw) (zlatarić et al., 2007). different views have been reported on the significance of the interalar width in selection of anterior tooth sizes. picard (1958) found that interalar width could be used to estimate widths of the maxillary anterior teeth. this was substantiated by wehner et al. (1967) who suggested extending parallel lines from the lateral margins of the alae of the nose onto the labial surface of the maxillary occlusal rim to estimate positions of the inter-canine cusp tips. hoffman et al. (1986) stated that there is a correlation of 0.413 between iaw and intercanine tip distance (ictd). a weaker correlation coefficient of 0.217 was observed between iaw and width of maxillary anterior teeth (wmat). ictd was 3% greater than iaw and wmat was 31% greater than iaw. aleem et al. (1997) reported that wmat is 26% greater than iaw. al-el–sheikh and al-athel (1998) found significant associations between iaw with (1) ictd and (2) wmat, and wmat was 56% greater than iaw. mavroskoufis and ritchie (1981) found a positive association between nasal width and ictd, which promotes its use in establishing the width of the anterior teeth. latta et al. (1991) reported significant differences in the iaw and ipd between races and sexes. the aims of the present study were to compare iaw, ictd, and wmat between males and females and to derive predictive equations from a group of iranian adults. materials and methods this was a cross-sectional study of iranian young adults. the sample of convenience consists of dental students from isfahan university. a total of 120 cases were analyzed (60 males; 60 females). inclusion criteria were: at least 18 years old of iranian descent; normal nose morphology without a history of rhinoplasty; intact maxillary six anterior teeth without history of orthodontic therapy; a class i normal occlusion without a diastema, spacing or crowding; and well aligned teeth in the maxillary arch (al-el–sheikh and relationship between width of maxillary anterior teeth and interalar distance mortaza bonakdarchian and reza ghorbanipour isfahan university of medical sciences hezar jerib avenue, isfahan, iran correspondence to: reza ghorbanipour, department of orthodontics, faculty of dentistry, isfahan university of medical sciences, hezar jerib ave., isfahan, iran 8174673461 email: dr_ghorbanipour@yahoo.com abstract there are few guides to estimate the size of denture teeth. the purpose of this observational cross sectional study of iranian adults was to evaluate the relationship between interalar width compared to intercanine tip distance and to the summed width of the maxillary anterior teeth in adults. the samples were selected from dental students in isfahan university. interalar width was measured with calipers. maxillary inter-canine distance was measured between cusp tips on dental casts. mesiodistal widths of the six anterior teeth also were measured. independent t-tests, pearson’s correlation coefficients, and linear regression were used for statistical analysis. mean interalar width was 36.38 mm (sd = 3.81), intercanine tip distance was 34.15 mm (sd = 2.05), and mean width of maxillary anterior teeth was 48.23 mm (sd = 2.07). there were significant associations between interalar width and summed widths of the maxillary anterior teeth and with intercanine distance. in addition, predictive equations for estimation of tooth sizes using interalar width were calculated by regression. these statistical relationships may also be useful forensically. dental anthropology 2010;23(2):53-56. 54 al-athel, 1998; hasanreisoglu et al., 2005). sliding calipers were used with an accuracy of 0.1 mm. each distance was measured 3 times and the average was recorded (gomes et al., 2009). iaw (fig. 1) was measured from the widest point on either nostril (zlatarić et al., 2007). irreversible hydrocolloid impressions (cavex ca37, cavex holland, bv, haarlenm, holland) of the maxillary teeth were made and poured with hard dental stone (begostone, bego, bremen, germany). the straightline distance between canine tips (fig. 2) was measured (hoffman et al., 1986). the maximum mesiodistal width of each anterior tooth was measured, and these widths were summed (coded as wmat) (gomes et al., 2009; hasanreisoglu et al., 2005). descriptive statistics, independent t-tests, pearson’s correlation coefficient, and linear regression analysis were used for statistical analyses using the statistical package for social sciences (spss inc., chicago, il, usa). results descriptive data are listed in table 1. results of independent t-tests show that the values of iaw, ictd and wmat were significantly greater in males than females. pearson’s r disclosed significant associations between iaw and ictd in females (r = 0.457; p < 0.05) and in males (r = 0.442; p< 0.05) and between iaw and wmat in females (r = 0.473; p < 0.05) and in males (r = 0.481; p < 0.05). the predictive equations for estimating tooth sizes from interalar width are summarized in tables 2 and 3. discussion in earlier studies, measurements were made using extracted teeth. recent studies measured tooth dimensions on casts or using computer-based images or intraoral evaluations (hasanreisoglu et al., 2005). it is generally agreed that selection of the width of anterior teeth should be based on facial measurements and proportions (al-el– sheikh and al-athel, 1998). it has been reported that the width of the nose may be used for selecting the size of the anterior teeth, for positioning the maxillary canines and for registering the curve of the anterior arch (hoffman et al., 1986). sex differences in the dimensions of the anterior teeth have been noted for most racial groups, with men exhibiting mesiodistally wider teeth than women (e.g., hasanreisoglu et al., 2005; strett et al., 1992; lavelle, 1972; richardson and malhotra, 1975). the mean of iaw was 36.37 mm in the present study. it was smaller than the means reported by mosharraf et al. 36.6 mm (2006), latta and weaver 43.9 mm (1991), dharap and tanuseputro (1997) 39.8 mm and was greater than the mean reported by hoffman et al. (1986) at 34.28 mm and al-el-sheikh and al-athel (1998) at 33.27 mm. in the present study the mean of ictd was 34.15 mm, which is smaller than means reported by dharap and fig. 1. measurement of interalar width. fig. 2. measurement of straight-line distance between the canine tips (intercanine tip distance) fig. 3. measurement of maximum mesiodistal width of maxillary incisor. m. bonakdarchian and r. ghorbanipour 55 tanuseputro (1997) 36.7 mm or hoffman et al. (1986) 35.35 mm or gomes et al. (2009) 37.44 mm. the mean of wmat in this study 48.23 mm was smaller than the mean reported by gomes et al. (2009) 53.67 and al-el-sheikh (1998) 52.22 mm and was greater than means reported by hoffman et al. (1986) 44.85 mm, al-wazzan (2001) 45.23 mm and shillingburg et al. (1972) 45.80 mm. the differences among studies would seem to be due to ethnic differences or, possibly, different measurement techniques. some studies used digital photography and obtained facial measurement from them, so they may have some errors because of the effect of the third dimension of anteroposterior length (gomes et al., 2009; hasanreisoglu et al., 2005), while others took measurements on the face (hoffman et al., 1986; al-el–sheikh and al-athel, 1998; mosharraf et al., 2006). al-el-sheikh and al-athel (1998) and mosharraf et al. (2006) measured dental dimensions intraorally and hoffman et al. (1986) used wax rim indices. hasanreisoglu et al. (2005) and gomes et al. (2009) measured dimensions from dental casts. genetic heritage would seem to be the main cause of variation between different groups (mcarthur, 1985; mavroskoufis and ritchie, 1981). participants in the current study were iranian, and this is one source of the observed differences among groups. there was a significant association between iaw and ictd in females (r = 0.457; p < 0.05) and in males (r = 0.442, p < 0.05), which agrees with the studies of hoffman et al. (1986) (r = 0.49, p < 0.05), mavroskoufis and ritchie (1981), and dharap and tanuseputro (1997) (r = 0.31, p < 0.05). in the current study there was a significant relation between iaw and wmat in females (r = 0.473; p < 0.05) and in males (r = 0.481; p < 0.05). hoffman et al. (1986), mosharraf et al. (2006), and al-el-sheikh and al-athel (1998) reported similar associations in their studies (p < 0.05). concerning the estimation of ictd from iaw, hoffman et al. (1986) found the ratio of 1.31 between iaw and wmat, this ratio was 1.30 in gomes et al.’s study (2009) and 1.26 in a study conducted by aleem et al. (1997) and 1.56 in al-el-sheikh and al-athel’s study (1998). other studies calculated the ratio of means, whereas we provide regression equations for estimating wmat from iaw, which is more useful. different results in this study are assumed to be due to different measurement methods, to ethnic differences, and to different methods of analyzing the data statistically. from a clinical perspective, we promote the predictive equations in tables 2 and 3 for estimating tooth sizes in iranians. these equations will help dentists provide iranian patients the best esthetics relative to their previous natural teeth and in harmony with their facial dimensions. conclusions within the limitations of the present study, the following conclusions were drawn: 1. the dimensions of iaw, ictd and wmat were larger in males. 2. there were significant relationships between iaw and ictd and wmat in each sex. acknowledgements this study (no. 385074) was supported financially by research center of isfahan university of medical sciences and health services), isfahan, iran. we are grateful to the department of prosthodontics in isfahan faculty of dentistry and all the students who participated in this study. literature cited aleem, ma, stipho hd, talic yf, khan n. 1997. the significance of inner canthal distance in prosthodontics. saudi dental j 9:36-39. al-el–sheikh hm, al-athel ms. 1998. the relationship of inter pupillary width and maxillary anterior teeth width in saudi population. odonostomatol tropicale 21:7-10. table 1. descriptive statistics sex n mean max min sd iaw† female 60 34.32 40.4 27.6 2.863 male 60 38.43 47.5 30.8 3.549 total 120 36.38 47.5 27.6 3.816 ictd female 60 33.25 36.3 29.1 1.735 male 60 35.05 40.2 31.2 1.962 total 120 34.15 40.2 29.1 2.052 wmat female 60 47.67 52.7 41 2.367 male 60 48.78 54.6 40 2.873 total 120 48.23 54.6 40 2.679 †iaw, interalar width; ictd, intercanine tip distance; wmat, width of maxillary anterior teeth. tooth size and interalar width table 2. predictive equation for estimation of ictd and wmat from iaw in males (y = a + bx) y x r p value predictive equation ictd iaw 0.442 <0.0001 ictd = 26.143 + 0.216 × iaw wmat iaw 0.481 0.0080 wmat = 43.807 + 0.129 × iaw 56 al-wazzan ka. 2001. the relationship between intercanthal dimension and width of maxillary anterior teeth. j prosthet dent 88:608-612. dharap as, tanuseputro h. 1997. a comparison of interalar width and intercanine distance in malay males and females. anthropol anz 55:63-68. frush jp, fisher dr. 1955. introduction to dentogenic restorations. j prosthet dent 5:586–595. gomes vl, gonçalves lc, costa mm, lucas bde l. 2009. interalar distance to estimate the combined width of the six maxillary anterior teeth in oral rehabilitation treatment. j esthet restor dent 21:26-35. hasanreisoglu u, berksun s, aras k, arsalan i. 2005. an analysis of maxillary anterior teeth: facial and tooth proportions. j prosthet dent 94:530-538. hoffman w jr, bombery tj, hatch ra. 1986. interalar width as a guide in denture tooth selection. j prosthet dent 55:219-221 keng sb. 1960. nasal width dimension and anterior teeth in prosthodontics. ann acad med singapore 15:311314. latta gh jr, weaver jr, conkin je. 1991. the relationship between the width of the mouth, interalar width, bizygomatic width and interpupillary distance in edentulous patients. j prosthet dent 65:250-254. lavelle cl. 1972. maxillary and mandibular tooth size in different racial groups and in different occlusal categories. am j orthod 61:29-37. young ha (1954) . selecting anterior tooth mold. j prosthet dent 4:748760. mavroskoufis f, ritchie gm. 1981. nasal width and incisive papilla as guides for the selection and arrangement of maxillary anterior teeth. j prosthet dent 45:592-597. mcarthur dr. 1985. determining approximate size of maxillary anterior artificial teeth when mandibular anterior teeth are present. part i: size relationship. j prosthet dent 53:216–218. mosharraf r. sadeghian s, farzan a, malekzadeh f. 2006. the relationship between the mesiodistal width of maxillary incisors and width of the mouth, interalar width, bizygomatic width and intercanthal distance. int j dental anthropology 8:22-30. picard jr. 1958. complete denture esthetics. j prosthet dent 8:252-259. richardson er, malhotra sk. 1975. mesiodistal crown dimension of the permanent dentition of american negroes. am j orthod 68:157-164. sellen pn, phil b, jagger dc, harrison a. 1999. methods used to select artificial anterior teeth for the edentulous patient: a historical overview. int j prosthodont 1999;12:51-58. shilllingburg ht jr, kaplan mj, grace sc. 1972. tooth dimension, a comparative study. j so calif dent assoc 40:830-839. strett jd oliver t, robinson f, fortson w, knaak b, russel cm. 1992. width/length ratios of normal clinical crowns of the maxillary anterior dentition in men. j clin periodontol 26:153-157. verjao fm, nogueira ss. 2005. intercommisural width in 4 racial groups as a guide for selection of maxillary anterior teeth in complete dentures. int j periodontol 18:513-515. wehner pj, hickey jc, boucher co. 1967. selection of artificial teeth. j prosthet dent 18:222-232. zlatarić dk, kristek e, celebić a. 2007. analysis of width/ length ratios of normal clinical crowns of the maxillary anterior dentition: correlation between dental proportions and facial measurements. int j prosthodont 20:313-315. m. bonakdarchian and r. ghorbanipour table 3. predictive equation for estimation of ictd and wmat from iaw in females (y = a + bx) y x r p value predictive equation ictd iaw 0.457 0.016 ictd = 28.187 + 0.145 × iaw wmat iaw 0.473 0.000 wmat = 42.194 + 0.159 × iaw rautman and edgar 2013.4 31 secular change in dental development in new mexican females anna l.m. rautman 1 , heather j.h. edgar 1 1department of anthropology and maxwell museum of anthropology, university of new mexico albuquerque, new mexico 87131 keywords: dental development; hazards analysis; secular change abstract recent research has indicated a dramatic acceleration of dental development in 20th century european americans in tennessee and arizona, resulting in developmental stages being reached at earlier calendar ages. in order to determine whether this rate change is also observed in new mexico, radiographs from two cohorts of european american female orthodontic patients with known ages were used to compare age by stage of development. the cohorts date to the 1970’s (n=101) and the 1990’s (n=93) and were between 5-11 years of age. dental developmental stages were recorded for five mandibular teeth. the average calendar age difference between cohorts per tooth and developmental stage combination was less than one month, but varies among tooth/stage combinations by up to 13 months. a pearson’s chi square test found no significant difference between the two cohorts for the 22 tooth/ stage combinations. however, cox hazards analysis demonstrated significant differences between the cohorts for five of the 22 tooth and stage combinations. contrary to previous findings, the calendar age of the 1990’s cohort is older for 16 of the 22 tooth/stage combinations than the 1970’s cohort. this runs counter to the general trend of acceleration in development observed in multiple systems. dental development is generally thought to be a precise method for estimating an individual’s chronological age during growth, because it seems to be less affected by environmental variation than long bone length. however, secular change has been documented in the timing of dental development (nadler, 1998; cardoso et al., 2010; o’neill, 2012; sasso et al., 2012). secular change refers to non-genetic, directional changes in the timing, rate, and magnitude of development over successive generations, often related to environmental factors (garn, 1987; o’neill, 2012). evidence of secular change has been reported across numerous populations and in many body systems, including height and age of menarche (cole, 2000; thompson et al., 2002; cardoso et al., 2010). previous research has shown that children in the united states and europe are reaching stages of dental development at younger ages then had previous generations (nadler, 1998; cardoso et al., 2010; o’neill, 2012; sasso et al., 2012). nadler (1998) noted that patients in tucson, arizona in the 1990’s who were described as caucasian and between 8.5-14.5 years were reaching stages of dental development at younger chronological ages than similar patients had in the 1970’s. specifically, he detected a reduction of 1.52 years in the obtainment of dental development stage g (demirjian et al., 1973) of the mandibular canine in females between two cohorts, 1972-1974 and 19921994. work by o’neill (2012) also showed an increase in the rate of dental development in patients described as american white from memphis, tennessee. this study examined the dental development of all mandibular teeth and found a 1.1-year reduction in chronological age relative to dental age between two cohorts from 1980-1985 and 2005-2010. research in europe has also demonstrated a reduction in age of dental development stage attainment. in portugal, modern girls were shown to have matured dentally 1.47 years faster than girls from half a century ago (cardoso et al., 2010). the historic sample was comprised of skeletons of individuals who died between 1903 and 1972, with the majority of the deaths occurring between 1920 and 1950. the modern sample was comprised of dental patients whose radiographs were taken between 1998 and 2006. for both samples, the first seven mandibular teeth were examined. a study in croatia of seven left mandibular teeth observed an acceleration of 0.83 years in girls’ rate of dental development between 1977-1979 and 2007-2009 (sasso et al., 2012). correspondence to: heather edgar department of anthropology and maxwell museum of anthropology, university of new mexico, albuquerque, new mexico 87131 hjhedgar@unm.edu 32 given an increase in the rate of dental development observed for europeans and european americans, this study examines whether there is evidence for secular change in the timing of dental development in european american females in albuquerque, new mexico. the hypothesis was that more recent patients obtained stages of dental development at younger ages than had patients in an earlier cohort. materials and methods the sample consists of 194 radiographs in two cohorts of female patients of european-american ancestry (edgar et al., 2011) who were less than 11 years old. one orthodontist in albuquerque, new mexico saw all the patients. cohort one included 101 radiographs of patients who were seen between 1973 and 1979. cohort two included 93 radiographs of patients seen between 1990-1999. while the patients were living in new mexico at the time of their treatment, how long they had lived in new mexico was not known. through observations of panoramic oral radiographs, one author (almr) assigned a dental development stage to every tooth, maxillary and mandibular, deciduous and permanent, using a 13 stage method commonly used in studies of dental development (hereafter referred to as "the moorrees method”) (moorrees et al., 1963 a,b; alqahtani et al., 2010). because of limited observations, only five teeth, all mandibular, are included in this analysis: the canine, both premolars, and the second and third molars. although direct scoring of the radiographs was completed using the moorrees method for dental development stages, scores were converted to stages described by demirjian (1973, hereafter referred to as "the demirjian method") so that results from the new mexico sample could be compared to those reached by nadler (1998) from tucson, arizona and o’neill (2012) in memphis, tennessee. the conversion used the written descriptions of the progress of dental development to match descriptions in the two methods. details of the conversion are shown in figure 1. an intra-observer error test was run on a subset of 40 radiographs, 20 from each cohort. the consistency between the two sets of observations was tested using weighted and unweighted cohen’s kappa tests (cohen, 1960; viera and garrett, 2005). the mean and median age and standard deviation were calculated for each developmental stage per tooth for each cohort. using the mean ages, pearson’s chi square was used to test for significant differences for each stage per tooth between the cohorts (gotelli and ellison, 2004). cox proportional hazards analysis (cox and oakes, 1984; fox, 2002) was used to analyze individual age differences in survivorship of each stage. in this analysis, the event of interest is the transition to the next development stage. individual ages represent the time observation. this allows for analysis of relative ages and frequency of individuals who survive to the stage. results intraobserver test the weighted kappa score testing intraobserver error for observations of the five mandibular teeth included in this analysis is 0.917, and the unweighted kappa score is 0.676. both kappa scores demonstrate agreement between observafig. 1. conversion between the demirjian method (a g) and the moorree’s method (ci – rc) dental development stages. anterior teeth are pictured on the left, posterior teeth on the right. 33 tion, “almost perfect agreement” and “substantial agreement,” respectively (viera and garrett, 2005). given the ordinal nature of the development stages, the weighted kappa is more applicable. dental development in new mexico: the moorrees method the mean age of dental development stages across all five teeth is younger in the 1970’s cohort than in the 1990’s cohort for the majority of stages. this indicates a slowing of dental development. this difference was usually small, with a mean absolute difference of 3.3 months. however, there are directional differences in which cohort is older for any given tooth/stage combination. because sometimes the 1970’s cohort is older for a given stage of development, and sometimes the 1990’s cohort is older, adding all differences between the cohorts together results in the 1990’s cohort being on average only 0.2 months older. table 1 presents the sample size and frequency per tooth/stage combinations, as well as pearson’s chi square and cox hazards analysis results. only two tooth/stage combination differences between cohorts were greater than six months: the canine at root one half (10 months) and the crown complete stage in the fourth premolar (13 months). of the 22 tooth/stage combinations, only six had measurable differences between mean ages older in the 1970’s cohort than in the 1990’s cohort. three of these tooth/stage combinations were in the second molar (crown threequarters, crown complete and root one-half). the other tooth/stage combinations seen at older ages in the 1970’s cohort were the canine (root complete), third premolar (root complete), and the fourth premolar (root one-quarter). of these six tooth/stage combinations, only the fourth premolar (root one-quarter) and second molar (crown three-quarter) had differences greater than one month, 3.81 months and 1.05 months, respectively. pearson’s chi square and cox hazards analysis disagree about significant differences between the cohorts. no pearson’s chi square result indicates significant differences in the mean or median ages between the two cohorts. this is true for all tooth/stage combinations, and regardless of whether the 1970’s or 1990’s cohorts showed any particular tooth/stage combination at an earlier age. in contrast, cox hazards analysis detects significant differences between cohorts (p < 0.05) in the survivorship of development stages as patients develop out of a given dental stage for five of the 22 tooth/stage combinations. timing of the canine (root one-half and root three-quarter), both premolars (third: root one-quarter; fourth: root initialized), and the second molar (root initialized) is significantly different between cohorts. of these five tooth/stage combinations, the mean difference was 5.4 months. the mean age of the 1990’s cohort was always older than the mean age of the 1970’s cohort. dental development in new mexico: the demirjian method after conversion of the observed moorrees method dental development stages to the demirjian method stages, the difference in mean ages between the two cohorts remains, with the 1990’s cohort mean being slightly older. the absolute mean difference is 3.01 months. when directional differences between the two cohorts were considered, the difference is 1.9 months with the 1990’s cohort as the older. only one tooth/stage combination difference is greater than six months (canine, stage f). of the 17 tooth/stage combinations considered, only five (canine, stage g; third premolar, stage g; fourth premolar, stage e; second molar, stage f; and third molar, stage c) had mean ages such that younger chronological ages were associated with development stages in the 1990’s cohort. the conversion of dental development scores from the morrees method to the demirjian method does not result in any significant pearson’s chi square tests of the mean age differences between the cohorts. cox hazards analysis of the demirjian method stage data demonstrates four of 17 tooth/stage combinations having significant differences in survivorship of stages between cohorts (p < 0.05). these four, canine (stage f), third premolar (stages e and f) and fourth premolar (stage d) have a mean age difference of 4.8 months. in all tooth/stage combinations the mean age of survivorship of the 1990’s cohort is older than the 1970’s cohort. 34 t a b l e 1 . s am p le s iz e f re q u en ci es a n d p -v al u es f o r p ea rs on ’s c h is q u ar e a n d c ox h az ar d s a n al y si s 35 arizona, new mexico, and tennessee compared all tooth/stages are seen at younger chronological ages in new mexico than in tennessee (o’neill, 2012). this difference ranges between 0.7 and 2.52 years, with an average difference of 1.52 years. a similar pattern with less difference between the samples is observed when new mexico and arizona are compared (nadler, 1998).the average difference between the southwest states is 0.69 years, with the arizona sample older. the range of differences is from the arizona sample being older by 1.39 years to the new mexico sample being older by 0.13 years. figure 2 shows the interquartile range for the new mexico and tennessee samples as well as a range of two standard deviations for the arizona sample, for which interquartile could not be computed. discussion considering the evidence for secular change seen by previous authors, it was expected that the 1970’s cohort would have achieved developmental stages at a later average age than 1990’s cohort. however, regardless of the method used to measure dental development, moorrees or demirjian, it is apparent that in new mexico, the 1970’s cohort achieved dental development stages at younger ages on average than the 1990 cohort. our results do not agree with the positive secular trend of dental development as observed previously in arizona, tennessee, portugal, and croatia. furthermore, the magnitude of difference in age between cohorts was much larger elsewhere, ranging from 0.83 years in croatia to 1.52 years in arizona, compared to the average difference of 0.42 years observed in new mexico. within the new mexico sample, the significant differences in the cox hazards analysis are primarily seen in eight and nine year olds. this observation raises the question of possible external and/or somatic environmental influences of dental development at that time. this age range generally falls between the mid-growth spurt and the adolescent growth spurt associated with puberty (eveleth and tanner, 1976; bailey, 1991; bogin, 1999). there is a slower period of body growth between early childhood and puberty. during this lull between the mid-growth spurt and the adolescent growth spurt the energy not used in skeletal growth is allocated elsewhere (hill and hurtado, 1996). one possible direction for this energy is social learning (hill and kaplan, 1999). at the same time, variation between individuals increases in multiple body systems throughout development (ogden et al., 2002; lin et al., 2006). since the period of greatest variability in dental development is correlated with a lull in skeletal growth, it may indicate that energy not being used in rapid skeletal growth is at least in part being diverted to dental development. while it appears that the mean age of dental development is not changing in new mexico, the mean ages in tennessee are getting progressively younger, getting closer to the early mean age already obtained in new mexico. this is true for the arizona sample as well, with one tooth/stage exception (canine, stage g). however, there are differences between the studies from arizona, new mexico, and tennessee in time periods from which cohorts were observed, complicating direct comparison. the first cohort in arizona and new mexico was taken from 1970’s patient records, while patients in the first cohort from tennessee were seen in the 1980’s. the second cohorts were from the 1990’s for arizona and new mexico and 2000’s for tennessee. conclusion this study finds no evidence of positive secular change of dental development among new mexican european american females, as had been observed previously in tennessee and arizona. in fact, the only significant differences detected show that the more recent new mexican cohort has less developed teeth at specific chronological ages, exactly opposite of the trend observed by nadler (1998) and o’neill (2012). causation is often an unexplored issue in studies of secular change. possible sources of change are external environmental factors such as nutrition, chemical exposure, and disease, as well as somatic environmental effects of energy allocation trade-offs between different body systems (kieser, 1992; kieser et al., 1997; euling et al., 2008; walker and hamilton, 2008; cardoso et al., 2010; patisaul and jefferson, 2010). in addition to external and somatic factors, there are genetic factors as well that may contribute to varied rates of dental development. while it is possible that genetic differences are the cause of the observed differences, the fact that all three studies were of european ameri36 fig. 2. age range per stage per tooth. can females makes this less likely. this would suggest that external and/or somatic environmental factors contribute to the results observed. to address this, a finer scale analysis of when changes in the pace of dental development occur is needed. such research should consider how the different external, somatic, and genetic factors interact with each other to influence dental development. literature cited alqahtani s, hector m, and liversidge h. 2010. brief communication: the london atlas of hu man tooth development and eruption. am j phys anthropol 142:481–490. bailey rc. 1991. the comparative growth of efe pygmies and african farmers from birth to age 5 years. ann hum biol 18:113–120. bogin b. 1999. patterns of human growth. 2nd ed. cambridge, united kingdom: cambridge uni versity press. cardoso hfv, heuze y, and julio p. 2010. secular change in the timing of dental root matura tion in portuguese boys and girls. am j hum biol 2009:245–275. cohen j. 1960. a coefficient of agreement for nomi nal scales. educational and psychological meas urement 20:37–46. cole tj. 2000. secular trends in growth. proc nutr soc 59:371–324. cox dr, oakes d. 1984. analysis of survival data. london: chapman and hall. demirjian a, goldstein h, tanner jm. 1973. a new system of dental age assessment. hum biol 45:211–227. edgar hjh, daneshvari s, harris e, and kroth pj. 2011. inter-observer agreement on subjects’ race and raceinformative characteristics. plos one 6:e23986. euling sy, herman-giddens me, lee pa, selevan sg, juul a, sørensen tia, dunkel l, himes jh, teilmann g, et al. 2008. examination of us pu berty-timing data from 1940 to 1994 for secu lar trends: panel findings. pediatrics 121. eveleth pb, tanner jm. 1976. worldwide variation in growth. cambridge, united king dom: cambridge university press. 37 fox j. 2002. cox proportional-hazards regression for survival data. in: an r and s-plus com panion to applied regression. garn sm. 1987. the secular trend in size and maturation timing and its implications for nu tritional assessment. j nutr 117:817–823. gotelli nj, ellison am. 2004. a primer of eco logical statistics. massachusetts, u.s.a.: sinauer associates, inc. hill k, kaplan h. 1999. life history traits in humans: theory and empirical studies. an nual rev of anthropol 28:397–430. hill kr, hurtado am. 1996. body size and the timing of sexual maturity. in: aché life history: the ecology and demography of a foraging people. new york: walter de gruyter, inc. p 341–373. kieser ja, groeneveld ht, da silva pcf. 1997. dental asymmetry, maternal obesity, and smoking. am j phys anthropol 102:133– 139. kieser ja. 1992. fluctuating odontometric asym metry and maternal alcohol consumption. ann hum biol 19:513–520. lin n-h, ranjitkar s, macdonald r, hughes te, taylor ja, townsend gc. 2006. new growth references for assessment of stature and skeletal maturation in australians. aust orthod j 22:1–10. moorrees cfa, fanning ea, and edward e. hunt jr. 1963a. age variation of formation stages for ten permanent teeth. j den res 42:1490–1502. moorrees cfa, fanning ea, and hunt eej. 1963b. formation and resorption of three deciduous teeth in children. am j phys anthropol 21:205– 213. nadler gl. 1998. earlier dental maturation: fact or fiction? angle orthod 68:535–538. o’neill km. 2012. a secular increase in the tem pos of tooth formation 1980-2010. ogden cl, kuczmarski rj, flegal km, mei z, guo s, wei r, grummer-strawn lm, curtin lr, roch af, et al. 2002. centers for disease control and prevention 2000 growth charts for the united states: improvements to the 1977 na tional center for health statistics version. pedi atrics 109:45–60. patisaul hb, jefferson w. 2010. the pros and cons of phytoestrogens. front neuroendocri nol 31:400–419. sasso a, špalj s, mady maričić b, sasso a, ćabov t, legović m. 2012. secular trend in the develop ment of permanent teeth in a population of istria and the littoral region of croatia. j forensic sci 57:1–5. thompson am, baxter-jones adg, mirwald rl, bailey da. 2002. secular trend in the de velopment of fatness during childhood and adolescence. am j hum biol 14:669–679. viera aj, garrett jm. 2005. understanding interobserver agreement: the kappa statistic. family medicine 37:360–363. walker rs, and hamilton mj. 2008. life-history consequences of density dependence and the evolution of human body size. curr an thropol 49:115–122. farrell 2009.4 93 the odontological collection at the royal college of surgeons of england is a vast research source consisting of a wide range of cranial and dental material. over 10,000 human and animal specimens are contained in the collection, all of which can be searched online and made available to researchers visiting the college by prior appointment. two themes are covered by the collection: (a) specimens displaying pathologies of the teeth and jaws and (b) material illustrative of dental development and growth. specimens displaying pathological conditions include a range of congenital, metabolic, and infectious diseases in addition to examples of maxillofacial trauma. developmental material includes human specimens from foetus to adult and a range of animal material that has the potential for extensive comparative anatomical studies. the diversity and ready availability of the odontological collection make it useful to researchers from a range of disciplines. this article presents a brief history to the collection, reviews its contents, hopefully, discloses its potential for academic investigation. details also are provided as to how to locate and navigate around the online catalogue ‘surgicat’ to perform general or specific searches. the origin of the collection dates back to the 1850s when the odontological society of great britain was founded. four years later the college of dentists was absorbed into this society, leading to the creation of a museum. in the early 1900s the odontological society was incorporated into the newly-formed royal society of medicine as its odontological section. the society’s collection was placed on loan to the royal college of surgeons in 1909, and in 1943 the collection was transferred to the college on a permanent basis. transference was a goodwill gesture towards reconstitution of the museum, which was grievously damaged by bombing in 1941. dental material from several sources has been collated throughout the last two brief communication: a unique dental resource: the odontological collection at the royal college of surgeons of england milly farrell* the royal college of surgeons of england. correspondence to: milly farrell. assistant curator, museums, the royal college of surgeons of england. 35-43 lincoln’s inn fields, london wc2a 3pe, great britain e-mail: mfarrell@rcseng.ac.uk fig. 1. the maxillae and mandible of a child aged 7 years 3 months, showing the developing dentition. the outer surface of the alveolar bone has been removed to expose the stages of development and eruption of each tooth type. from the collection of sir john tomes. abstract this report describes the development of a searchable electronic data base of the dentally-relevant holdings of the royal college of surgons of england. this odontological collection is accessible through the world wide web at http://surgicat.rcseng.ac.uk/. highlights of a few of the holdings are described here along with information for accessing the collection. dental anthropology 2009;22(3):93-95. 94 centuries, the majority having originated from eminent surgeons, dentists, and zoologists who made regular donations to this ever increasing research source. significant figures in the field of dentistry made regular contributions to the collection, often of personally prepared skeletal material that exposes root formation or developing permanent teeth (fig. 1). such individuals include the seminal dentists sir john tomes, his son charles, and sir edwin saunders. some specimens are of particular historical interest, such as the short twine necklace of 38 human teeth brought back from the congo river by the explorer henry morton stanley, and the selection of teeth retrieved from soldiers in 1815 who perished during the battle of waterloo. the most recent contribution was sir winston churchill’s dentures, donated in 2000. some of the human material is archaeological in acquisition. those obtained through excavation include the over 100 skulls assessed by a. e. w. miles in order to formulate his renowned dental ageing chart based on tooth wear. these skeletal remains were unearthed from an iron age camp at breedon-on-thehill in leicestershire, england, during the 1940s. miles measured the areas of occlusal wear facets on the molar teeth and thereby calculated a rate of attrition through the stages of complete eruption to old age. the skulls used in this study are stored alongside miles’ original notes for each individual. a diverse range of archaeological sites are represented in the collection, on both a temporal and geographic scale. remains from seven romano-british sites have been incorporated, the large majority of which have complete dental arcades and generally show little dental displacement or disease. furthermore, over 100 cranial specimens have been donated from two medieval burial sites in central london. both of these populations show a range of non-metric traits and pathologies, including microdontia, supernumerary teeth and diseases that generally correlate with poor oral hygiene. finally, there is a broad geographic range of archaeological sites represented in the collection, including three egyptian mummy skulls and four guanche mandibles (the indigenous inhabitants of the canary islands). the human material is a rich resource for the study of dental development, as all ages are represented, both in skeletal form and in casts or models. over 200 sets of perinatal dentitions were collected during the 1950s and have subsequently been used to form the basis of doctoral research into the construction of a new dental ageing atlas, which is currently available through the queen mary university of london website (alqahtani, 2008). other material shows abnormalities in dental placement, from simple transpositions to the eruption of teeth into the zygomatic bone or even into the nasal fossa. all varieties of non-metric traits have been noted in the extensive array of individual mounted teeth showing the gradations of such anomalies (fig. 2). sets of molars have been mounted to effectively show the varying degrees of supernumerary cusps, such as parastyles and the cusp of carabelli. similarly, traits such as microdontia, anodontia and the presence of supernumerary teeth can be seen in prepared sections of the mandible and maxilla (fig. 3). in addition to the skeletal and dental specimens, the large collection of dental casts illustrates a range of diseases and injuries, from congenital abnormalities such as cleft palates in their respective stages of repair, to maxillofacial gun shot injuries of soldiers from the first and second world wars. concurrently, there are a few human specimens housed within the collection that do not relate specifically to the categories of development or pathology, but are potentially of a wider anthropological value. examples include several skulls displaying variations in intentional modification of the dentition through dental filing, chipping or staining. casts have been included fig. 2. five molar teeth from different individuals showing enamel pearls in the region of the root furcation. fig. 3. the maxillae showing abnormality in positioning of the teeth and the presence of supernumerary teeth. the normal positions of the central incisors are occupied by two tubercle-shaped teeth. the left central incisor is misplaced and the right central incisor appears absent. from the collection of sir edwin saunders. m. farrell 95 alongside this sample to show variations in modification between cultural groups. a large proportion of these crania are javanese in origin, having been donated by the anthropologist joseph barnard davis in the late nineteenth century (fig. 4). the effect of occupational or habitual activities on the dentition is a related theme. such use of the teeth as tools is noticeable in the casts of eskimo teeth depicting the practice of leather softening through mastication and the various sections of jaws showing pipe facets. while approximately one-third of the collection is composed of human material, the remaining twothirds consist of crania from a range of faunal taxa. of the over 7,000 animal cranial specimens, some 4,000 are primates, including a significant number of specimens donated by the late primatologist sir william osman hill. a wide variety of primates are represented in the collection, from the largest, the gorilla, to the smallest, the mouse lemur. this diversity in both animal species and geographic habitat holds the potential for extensive comparative study. of the extinct species represented, the large majority are fossilised specimens that hold the potential for paleontological investigation. however, specimens of the more recently extinct thylacine wolf (thylacinus cynocephalus) are incorporated in the collection as complete skulls or partial maxillae and mandibles. the collection also contains over 250 carved and un-carved ivory specimens that originate from both terrestrial and marine mammals, which could be used to form the crux of a variety of research projects. the range of species, the geographical spread of the collection, and the quantity of specimens stored, make the faunal material a valuable resource for comparative studies, especially in the field of evolutionary anatomy. the latest stage in the recataloguing of the odontological collection began last october, with an aim to be completed by the end of 2010. all specimens are now listed on the online catalogue ‘surgicat’ and can be searched by anyone with internet access at http://surgicat.rcseng.ac.uk/. the initial search page of surgicat contains a ‘free search’ box under which one can search for specimens recorded under any category. a broad search of criteria such as taxon name, pathological term or acquisition source will promptly detail all relevant records in the museum’s collections. for more specific searches, or to combine a set of queries, the ‘expert search’ system can be used. the human collection is now fully documented and fig. 4. cranium of a 25 year old male from the maluku islands, indonesia, showing modification of the anterior teeth. quadrilateral reliefs have been filed into the labial surfaces. the left central incisor was lost postmortem. donated by joseph barnard davis in the late 19th century. all specimens are recorded by description and have attached photographs where relevant. recataloguing the animal material began in july of this year and is an ongoing project. the odontological collection is an unparalleled source of dental information, the potential of which is yet to be fully realised. it is hoped that this overview provides some insight into the sheer scope of the odontological material contained and encourages prospective enquirers to refer to the collection in future study. for details on accessing the odontological collection, or for any further help with performing surgicat searches, please contact milly farrell (mfarrell@ rcseng.ac.uk). literature cited alqahtani s j. 2008. atlas of tooth development and eruption. ph.d. thesis, barts and the london school of medicine and dentistry, queen mary university of london. odontological collection khudaverdyan 2011.2 42 ortner and putschar (1981) claim that infectious diseases were the single greatest threat to life of prehistoric infants and children. but this does not mean that adults were immune. of people surviving into adulthood, many will die of infectious disease, whether it be direct or indirect (ortner and putschar, 1981). there are a host of biological and environmental factors that influence the prevalence of infectious lesions found in prehistoric skeletal samples. early hominid populations likely were too small and dispersed to support many of the acute communicable pathogens common to densely populated sedentary communities (burnet, 1962), especially those for which humans are the only disease pool (cockburn, 1971; polgar, 1964). pathogens such as smallpox, measles, and mumps were unlikely to afflict early hominid groups (cockburn, 1967a). viruses such as chickenpox and herpes simplex may survive in isolated family units, suggesting that they could have been sustained in early dispersed and nomadic groups. the shift to permanent settlements created larger aggregates of potential human hosts while increasing the frequency of interpersonal contact within and between communities, likely fostering the spread and evolution of more acute infections (ewald, 1994). accumulation of human waste would have created optimal conditions for dispersal of macroparasites and gastrointestinal infections. the appearance of domesticated animals such as goats, sheep, cattle, pigs, and fowl provided a novel reservoir for zoonoses (cockburn, 1971). tuberculosis, anthrax, q fever, and brucellosis could have been readily transmitted through the products of domesticated animals such as milk, hair, and skin, as well as increased ambient dust (polgar, 1964). the analysis of skeletal lesions resulting from infectious disease on prehistoric human skeletal material offers the osteologist insights into the interplay among many considerations, such as disease, diet, ecology, social structure, warfare, settlement pattern, plant and animal domestication, sanitation level, immunological resistance, and psychological stress (larsen, 1997). when an individual is infected by an organism, there are three ways in which a bone can become involved. first, the infection can spread from its primary source to skeletal elements by way of the blood stream. second, an injury (such as a penetrating wound) can leave a bone open to direct infection. third, a localized soft tissue infection can be so severe that it spreads to the underlying bone (aufderheide and rodriguez-martin, 1998). the basis of the present study are four skeletal collections from the the sevan region of armenia, plus two from the shiraksky plain. figure 1 shows the spatial perspective of these sites. the armenian highland—also the anthropology of infectious diseases of bronze age and early iron age from armenia a. yu. khudaverdyan institute of archaeology and еthnography national academy of science, republic of armenia, yerevan, 0025, charents st.15 correspondence to: anahit khudaverdyan, institute of archaeology and еthnography, national academy of science, republic of armenia, yerevan, 0025, charents st.15 e-mail: ankhudaverdyan@gmail.com akhudaverdyan@mail.ru abstract this study reviews the evidence for the presence of specific infectious diseases in armenian skeletal series of bronze age and early iron age. throughout human history, pathogens have been responsible for the majority of human deaths. factors such as age, sex, and nutritional status can influence whether an individual contracts and develops a particular infection, while environmental conditions, such as climate, sanitation, pollution, and contact with others will affect the susceptibility of a population. the frequencies of such signs as osteomyelitis, peridontal disease, leprosy, abscesses, and so forth, testify that the people experienced a variety of forces and durations— both internal and external—of stressful influences. individuals from sevan region may have had more chronic infections due to continued exposure to pathogens during their lives as well as traumatic injuries. seven individuals had nasopharyngeal lesions consistent with a diagnosis of leprosy. dental caries was less severe in the sevan region, although dental abscesses (51 individuals) and antemortem tooth loss (87 individuals) were more prevalent. in contrast, periodontal disease (8/18 adults) and antemortem loss (8/18 adults) of the molars were more prevalent at the shiraksky plain. data focusing on climate influence, migratory, and cultural habits in the past are discussed. dental anthropology 2011;24(2):42-54. 43 known as the armenian upland, armenian plateau, or simply armenia (hewsen, 1997)—is the central-most and highest of three land-locked plateaus that collectively form the northern sector of the middle east (hewsen, 1997). the armenian plateau has been a crossroads linking the worlds of east and west (martirosyan, 1964). the areas surrounding the black sea coast at certain stages of history became a center of interrelations of multiple cultures. overland lines of contact existed between the near east through the armenian highlands and the caucasus and on to the balkans, and through caucasus and the balkans to the north black sea coast and in the return direction. the ethnic history of the region developed under the interaction of various groups since the early bronze age, among which the indo-european played a leading role, those tribes having created one of the most advanced cultures of the then-contemporary world (khudaverdyan, 2011a,b). late bronze age and early fig. 1. map of the republic of armenia.main sites are discussed in text. fig. 2. a burial from the black fortress (photo s. termarkaryan). evidence of infectious diseases in bronze age armenia 44 iron age also mark the time of contact between eurasians in this area (khudaverdyan, 2011a,b). according to the archeological record (kyshnareva, 1990), it was a time of expanding population. trade networks expanded and social systems grew more complex. increasing migration and trade between state-level societies in eurasia led to the convergence of regional infectious disease pools. the economy in armenia was based on forms of mixed agriculture. analysis of the faunal remains indicates that cattle and sheep and goat herds were managed for many purposes such as milk, wool, skin, meat, and other secondary products. at the armenian necropolis in the late bronze age among the usual graves with human skeletons there were burials of a horses and a chariot burial (khudaverdyan, 2009, 2011b). the exploitation of wild animals continued as hares and wild birds have been found at sites in the region. the rites of single or multiple inhumations started in the bronze to early iron age and were located in settlements, in well-defined burial areas. individuals’ remains were accompanied by grave goods of metalwork (jewelery and weaponry), pottery, and joints of meat. little is known about the health status and epidemiological aspects of historic armenia (khudaverdyan, 2010), but the quality of life of the members of past societies can be assessed by analyzing their remains (larsen, 1997). together with osteometric study, pathological examination can provide useful information on the biological aspects of a skeletal series. burial grounds from the lanjik and black fortress are located in the shiraksky plain. archaeological and anthropological monuments are common from in two time periods: the first half of the iv-iii millennium b.c. (lanjik) and the beginning of ii millennium b.c. (black fortress). the yerevan medical university had an archive of paleopathological specimens from a. sarafyana, which had been taken for the khudaverdyan report (2005; sarafyan and khudaverdyan, 1999). this provides 17 adults from sarykhan (ca. xi-ix/ viii b.c.), 126 adults from lchashen (ii-i millennium b.c.), 4 adults from karmir (ca. iх-viii b.c.), and a sample of 28 individuals from akynk (ca. xiii-xii b.c.). it is only recently that these skulls have been studied for evidence of disease. materials and methods the human remains that were analyzed for this article were excavated by a gyumri team under the directions of levon petrosyan and stepаn ter-markaryan (the sites of landjik and the black fortress). this is a most important culture of early bronze age in armenian highlands called the kura-araxes culture (landjik burial). one mass burial from the landjik site (end of the fourth millennium and beginning of the third millennium) has been excavated, and it contained remains of at least 10 individuals, together with rich archaeological grave goods (petrosyan, 1996). most of these skulls were in a good state of preservation (2 males, 5 females). two children (2-9 years) and 1 juvenile between 13 and 19 years of age were the only non-adults present in the sample. the site of black fortress is remarkable due to the archaeological presence of two time periods of ancient armenian history (late bronze age and ancient period, dating from the 1st century b.c. to the 3rd century a.d.). many sites are found here with a very large cemetery. the black fortress site (2nd millennium b.c.) is a regular cemetery (fig. 2) has been excavated since 1993, and the excavations are still ongoing (ter-markaryan, 1991; termarkaryan and avagyan, 2000; avagyan, 2003). this cemetery was located near the aleksandrаpol tower in the city gyumri. all of the burials appear to have been typical late bronze age interments, oriented in an eastwest direction. intentionally interred remains of small animals were common. the majority of animal remains recovered at black fortress were horned livestock and reptiles (especially turtle) (avagyan, 2003). a total of 13 skeletons were exhumed from a burial that included 2 males, 8 females and 3 children (4-9 years). an excavator disinterred skulls in the village of sarykhan. due to this information, a survey was conducted, which led to the beginning of an archaeological excavation. it was supervised by a. piliposyan (yerevan), and the excavations were developed in 1984. group sarykhan contained some 17 individuals. the distribution of sex is predominantly female (9 individuals: 24% of young adults (20-40 years), 18% of middle 11.8% of old adult). of these, 8 were male (6% adoolescent, 6% young adults, and 18% middle and 18% older adults) (sex and age from the unpublished data of a. sarafyan) (khudaverdyan, 2005). the lchashen site is a mass burial (n ≈ 500) which includes at least 126 individuals of both sexes and all ages (alekseev, 1974), accompanied with many stone and bone tools as well as ornamental objects. many sites are found surrounding this large cemetery that was excavated in 1957-1967 (mnacakanyan, yerevan), and the excavations are ongoing. the distribution of sex is predominantly male (62 individuals), and 23 were females (alekseev, 1974). group karmir (archaeologist a. piliposyan) contained 4 individuals. the distribution of sex is three female (middle adult) and one was male (old adult) (from the table 1 number of individuals included in the study males females total lanjik 2 6 10 black fortress 2 8 13 sarykhan 8 9 17 lchashen 62 23 85 akynk 16 12 28 karmir 1 3 4 a.y. khudaverdyan 45 unpublished data of a. sarafyan) (khudaverdyan, 2005). the akynk includes at least 28 individuals (kochar et al,. 1989). the analysis uses traditional approaches for the assessment of the general physical characteristics of the age at death and sex in the samples. age-at-death and sex were assessed through the use of multiple indicators. morphological features of the pelvis and cranium were used for the determination of sex (phenice, 1969; buikstra and ubelaker, 1994). a combination of pubic symphysis (gilbert and mckern, 1973; katz and suchey, 1986; meindl et al., 1985), auricular surface changes (lovejoy et al., 1985), degree of epiphyseal union (buikstra and ubelaker, 1994), and cranial suture closure (meindl and lovejoy, 1985) were used for adult age estimation. for subadults, dental development and eruption, long bone length, and the appearance of ossification centers and epiphyseal fusion were used (moorrees et al., 1963a,b; ubelaker, 1989; buikstra and ubelaker, 1994). dental inventory and recording of pathologies were collected using standards and forms found in buikstra and ubelaker (1994). periodontal disease was assessed by measuring the amount of alveolar bone loss. measurements were taken from the cemento-enamel junction to the surface of the alveolar bone. only those measurements that exceeded 2 mm were recorded as evidence of periodontal disease (tumer et al., 1991). caries were recorded based on the system devised by moore and corbett (1971, in buikstra and ubelaker, 1994:55). dental caries were recorded for each tooth and surface affected. care was exercised in order to avoid confusing legitimate caries with pulp exposure due to severe wear. abscesses were recorded based on their presence and location. buccal or labial lesions were differentiated from lingual perforations (see buikstra and ubelaker, 1994:55; tumer et al., 1991). antemortem tooth loss (atl) was based on evidence of resorption of alveolar bone around a tooth socket. if remodeling was evident and the socket was partially or fully filled in, then a tooth was considered to have been lost antemortem. sockets that were open and smooth, with no evidence of remodeling, were recorded as postmortem loss (tumer et al., 1991). enamel hypoplastic defects—a deficiency of enamel thickness, which is normally smooth, white, and translucent—were divided into linear, pit, and plane defect types (hillson, 1996). to determine the effects of stress on the bone, special indicators can be used that allow one, with various degrees of accuracy, to speak of adaptive complexes within the populations (goodman et al., 1984; goodman and rose, 1990). results and discussion skeletal indicators of health: infection osteomyletis is a combination of inflammation of the bone (osteitis) and the bone marrow (myelitis) by pus producing bacteria (aufderheide and rodriguezmartin, 1998). severe osteomyelitis and osteitis are caused by the spread of staphylococcus and streptococcus microorganisms. depending on the virulence of the microorganisms and/or host resistance, the reaction may be localized and acute or chronic and systematic (goodman et al., 1984). ortner (2003) points out that other infectious agents, such as viruses, fungi, and multicelled parasites can also affect the bone marrow. the skeletal changes consist of bone destruction along with new bone formation (involucrum) and necrotic bone (sequestrum) (aufderheide and rodriguez-martin, 1998). another typical manifestation of osteomyelitis is the formation of cloacae (drainage canals) that may be present in many cases. osteomyelitis does not only occur in an acute form, but also in a subacute as well as a chronic form that can reappear over a period of several years and, according fig. 3. оsteomyelitis. materials from excavation of burial ground akynk (burial 11, ♂ 35-40 years). fig. 4. subacute osteomyelitis of the upper jaw; inflammation of an antrum of highmore; facies leprosa. materials from excavation of burial ground lchashen (burial 52, ♀ 30-35 years old). evidence of infectious diseases in bronze age armenia 46 to larsen (1997), it can be the response to systemic or localized stress. death can occur if the infection spreads from the bone to the circulatory system and finally affects vital organs. if osteomyelitis heals, the bone becomes dense and becomes part of the normal cortical tissue and sclerotic scarring may occur (larsen, 1997; ortner, 2003). aufderheide and rodriguez-martin (1998) discussed that acute osteomyelitis can result from infections due to compound fractures, injuries, or surgery, and it occurs most frequently in adults over 40 years of age. figure 3 shows a middle adult male approximately 40 years old in group akynk, diagnosed with severe osteitis and periodontal disease. this unfortunate individual had lesions on his entire skull. the cranium of exhibits lesions on the frontal and left temporal bones. the frontal contains 2 lesions ranging in size from <0.2 mm to 0.3 mm in length and sclerotic reaction. the left temporal contains 1 small indentation on the side of the occipital bone along with a sclerotic reaction. in the woman (30-35 years old) from lchashen (burial 7), acute hematogenous osteomyelitis of the frontal sinus is revealed along with dental abscesses (fig. 4). periapical abscesses can be fatal if the resulting infection spreads into the sinuses. development of odontogenic osteomyelitis is visible in the region of upper right incisors, and the canine tooth was the source of a secondary defect of an antrum of highmore. the antritis was accompanied by an osteomyelitis and destruction of the forward wall of a sinus. the sharp antritis has been complicated by the distribution of inflammatory process on a trellised labyrinth of the frontal sinus. the margin of the main erosion was marked by a number of small distinctive sublesions in the outer table, comprising groups of small pits having an apparent sclerotic margin clustered around a small region of intact outer table. some of these sublesions were present in isolation on other parts of the frontal bone (fig. 4). the frontal bone is diploic with a marrow cavity capable of developing osteomyelitis. a typically fluctuant swelling fig. 5. оsteomyelitis and facies leprosa. materials from the excavation of burial ground sarykhan (burial 11/2, ♂ 50-55 years old). fig. 6. оsteomyelitis. materials from excavation of the burial ground lchashen (burial 27, ♂ 30-35 years old). fig. 7. osteomyelitis in the temporomandibule joint and porotic hyperostosis on the skull. materials from excavation of burial ground lchashen (burial 7, ♂ 45-50 years old). a.y. khudaverdyan 47 over the forehead known as “pott’s puffy tumor” after sir percival pott who described the condition in 1760, results from frontal sinusitis and osteomyelitis eroding the anterior table of the frontal bone. the term pott’s puffy tumor has been applied to any scalp swelling associated with frontal sinusitis. some prefer to limit the term to the swelling overlying and area of osteomyelitis in a diploic bone and use the term “a ruptured frontal sinus” for those associated with frontal sinusitis (thomas et al., 1977). it is a serious life-threatening complication of frontal sinus infection. pott’s pufty tumor and its complications result from the unique anatomy of the frontal sinus. the sinus is separated from the frontal bone marrow by only 100 to 300 μm. the sinus mucosa, marrow cavity and frontal bone have a common venous drainage via valveless diploic veins (breschet’s canals). frontal sinus infection can thus invade the marrow cavity causing osteomyelitis and erode through the thin anterior and posterior table, producing subperiosteal and extradural abscess, respectively (feder et al., 1987; lund, 1987). figure 5 shows a middle adult male approximately 50 years old in group sarykhan (skull 2, burial 11), diagnosed with severe osteomyelitis and dental abscesses. the frontal bone contains 1 lesion about 2 cm in length with sclerotic reaction. chronic osteomyelitis occurs more frequently in the mandible than in the maxilla and is often associated with suppuration. it is usually diffuse and widespread (lavis et al., 2002; eyrich et al., 2003). kazunori yoshiura (reinert et al., 1999) classified mandibular osteomyelitis into four patterns, as lytic, sclerotic, mixed, and sequestrum patterns. our case presented with the last pattern. chronic osteomyelitis will result in deformity of the affected bone (fig. 6). with an infection of the bone, the subsequent inflammatory response will elevate the overlying periosteum, leading to a loss of the nourishing vasculature, vascular thrombosis, and bone necrosis, and ending in formation of sequestrae. figure 6 confirmed the presence of a deep sequestra. although most cases of chronic osteomyelitis of the jaws result from dental origins, other sources of infection are possible (eyrich et al., 2003). it may also occur following penetrating trauma. viral fevers (e.g., measles), malaria, anemia, malnutrition may also to contribute to the development of osteomyelitis. at lchashen, 27 adults showed evidence of osteomyelitis in the mandible. the inflammation of a mandible joint (figs. 7-8) can arise as hematogen metastatic as a result of general infectious diseases such as scarlet fever, diphtheria, measles, dysentery, or typhus, and owing to contact distribution of an infection: an osteomyelitis of an ascending branch of the bottom jaw or a purulent otitis. the mandible joint of a skull (lchashen: burials 7, 62, figs. 7-8; black fortress: burial 9) expresses the presence of small sclerotic reactions. fig. 8. mandibular condyles with porous surface. materials from excavation of the burial ground lchashen (burial 62, ♂ 30-35 years old). fig. 9. dental abscesses. materials from excavation of burial ground of akynk (burial 7/2, ♀ 40-45 years old). fig. 10. subacute osteomyelitis in the upper jaw. the adsorption is almost complete in numerous regions of the alveolus. note the extreme pitting of the palatine bones and the extensive dental wear. materials from excavation of the burial ground of lchashen (burial 83, ♂ 50-55 years old). evidence of infectious diseases in bronze age armenia 48 dental abcesses abscesses of a tooth lead frequently to its exfoliation and cause a remodeling process that usually destroys the alveolus and reduces the size of the alveolar process at the site of the tooth loss (ortner, 2003). some researchers note that abscesses are caused by streptococcus milleri, fusobacterium nucleatum, or streptococcus mitis (lewis et al., 1986). abscesses can be instigated by various conditions, such as pulp necrosis, periodontal infection, or trauma. periapical abscesses can be fatal if the resulting infection spreads into the sinuses (fig. 4). although periapical abscesses can occur on the roots of any tooth, herrera et al. (2000) conclude that molars are most frequently affected with an occurrence of 69%. most abscesses happen in patients that already suffer from periodontal disease (herrera et al., 2000). in lchashen, 41 adults suffered from dental abscesses. regarding the skeletons from lanjik, three adults showed evidence of dental abscesses. at sarykhan, seven adults showed evidence of dental abscesses, which was higher than in the akynk group (fig. 9), where only one individual was affected. in the group from the black fortress, one adult suffered from dental abscesses (khudaverdyan, 2009). two out of four dentitions from karmir showed evidence of dental abscesses. periodontal disease peridontal disease is the inflammation of the soft tissues of the mouth, namely the gums, and/or the peridontal ligament, and alveolar bone (levin, 2003). retraction of the gums exposes the vulnerable root of the tooth to attack by acidic plaques, commonly resulting in caries, abscesses and antemortem tooth loss. periodontal disease is caused by several irritants such as bacterial plaque that becomes calculus due to calcification of plaque, and living or dead microorganisms (clarke, 1990; aufderheide and rodriguez-martin, 1998; ortner, 2003). another cause of periodontal disease can be gingivitis, an inflammation of the surrounding soft tissues (ortner, 2003). gingivitis can be caused by penetrating foreign bodies, major fig. 11. teeth lost during life. materials are from an excavation of burial ground sarykhan (burial 3/12, ♂ 6065 years old). fig. 12. dental caries and antemortem tooth loss. materials from the excavation of the burial ground at lchashen (burial 13, ♂ 30-35 years old). fig. 13. eample of dental caries. materials from excavation of the burial ground of black fortress (burial 14 , ♂ 25-30 years old). local trauma, or, indirectly, the loss of interproximal contacts (aufderheide and rodriguez-martin, 1998). in a progressive phase of periodontal disease, the roots of the teeth may be exposed and tooth loss may occur. it occurs interdentally and creates vertical defects between the root of the tooth and the alveolar bone. most commonly, the posterior teeth, the second and the third molars, are affected (clarke, 1990; aufderheide and rodriguezmartin, 1998). clarke (1990) and larsen (1997) point out that if periodontal disease is unchecked and untreated, the bony support for the teeth diminishes and exfoliation can occur. once a tooth is lost, the alveolus will be remodeled. furthermore, larsen (1997) lists the influencing factors, a.y. khudaverdyan 49 three adults showed evidence of periodontal disease. for the individuals from karmir and akynk periodontal disease was not noted. those teeth lost during life (fig. 11) were not counted as periodontal disease because other conditions can also cause tooth loss, such as accidents or interpersonal violence. antemortem tooth loss antemortem tooth loss is characterized by the presence of abscess and/or remodeling of the alveolar bone obliterating the tooth sockets. specific etiologies of antemortem tooth loss are problematic, as evidence may have been lost, especially in instances of carious teeth; however, the close association between periodontal fig. 14. facies leprosa: rhinomaxillary changes. materials from the excavation of burial ground karmir (burial 1, ♂ 50-55 years old). fig. 15. facies leprosa: rhinomaxillary changes. materials from the excavation of burial ground lchashen (burial 73, ♀ 50-55years old). fig. 16. multiple lesions of the skull. materials from the excavation of the burial ground lchashen (burial 31, ♂ 30-35 years old). fig. 17. multiple lesions of the skull. materials from excavation of the burial ground lchashen (burial 79, ♂ 45-50 years old). evidence of infectious diseases in bronze age armenia such as bacteria, poor oral hygiene, malocclusion, nutritional status, pregnancy, and psychological stress. there are four main types of periodontal disease, namely prepubertal, pubertal, rapidly progressive, and adult periodontis (hildebolt and molnar, 1991). of these four, only the last was observed in skeletons from armenia. in the samples from armenia, peridontal disease was present in 35 individuals. periodontal disease was the most common dental pathology among the landjik burials. a total of 4 out of 10 observable dentitions possessed some form of alveolar bone loss. on average there was greater bone loss on the mandible than the maxilla. the trend of periodontal disease in lchashen (24 adults) was one of slightly greater involvement than that observed in the black fortress group. four out of 13 dentitions showed evidence of alveolar bone loss. at sarykhan, 50 disease, dental caries, and antemortem tooth loss is well established, especially in archaeological series (larsen, 1997). the prevalence of antemortem tooth loss contributes to the overall picture of oral health in a sample. for the group from landik, antemortem tooth loss occurred in 4 adults. also, four adults from the black fortress met the criteria for antemortem loss. at lchashen, 72 adults showed evidence of antemortem tooth loss. antemortem tooth loss were observed in 7 people from sarykhan, 2 from karmir, and 6 from akynk. dental caries tooth analysis plays an important role in anthropological research. teeth are a rich “archive” that tell us about health and nutritional status, individuals and collective ancient and modern habits and life styles (powell, 1985; moggi cecchi and corruccini, 1993; milner and larsen, 1991). dental caries is an infectious disease that destroys the tooth structure, the root and the crown (brothwell et al., 1967; aufderheide and rodriguezmartin, 1998). ortner (2003) mentions that caries are caused by acid-producing bacteria in dental plaque that initiate the destructive process. larsen (1997) argues that caries do not refer to lesions in teeth resulting from the invasion of microorganisms, but that the disease is characterized by the focal demineralization of dental hard tissues by organic acids produced by bacterial fermentation of dietary carbohydrates, especially sugars. according to larsen (1997), there are several modifying factors for the development of dental caries: crown size and morphology, enamel defects, occlusal surface attrition, food texture, oral and plaque ph, speed of food consumption, some systemic diseases, age, child abuse, heredity, salivary composition and flow, nutrition, periodontal disease, enamel elemental composition, and the presence of fluoride and other geochemical factors. in lchashen, 2 adults suffered from dental caries (fig. 12). caries were observed in 6 people from landjik (3/8) and the black fortress (3/10; fig. 13) (khudavedyan, 2009). in individuals from karmir, akynk and sarykhan there was no instance of dental caries. leprosy (hansen’s disease) leprosy is a chronic infectious disease caused by mycobacterium leprae transmitted through contact with skin lesions or through inhalation of droplets containing the pathogen that are coughed or exhaled into the air by infected individuals (roberts and manchester, 2005). true leprosy is a chronic, debilitating, and disfiguring infection. this process can result in loss of fingers, toes, nasal tissue, or other body parts. leprosy varies in expression from a mild, or tuberculoid, infection (also known as highresistance leprosy) to the most severe infection, referred to as the lepromatous type (also known as low-resistance leprosy) (andersen et al., 1994; ortner, 2003). skeletal involvement can occur with any degree of infection, but it is most acute in the lepromatous form. however, the skeleton is not affected in most cases; only 5% of individuals with leprosy develop bony lesions (ortner, 2003). changes in the bones of the face can accompany lepromatous leprosy and are collectively known as the rhinomaxillary syndrome or ‘facies leprosa’ (møllerfig. 18. multiple lesions of the skull. facies leprosa: rhinomaxillary changes. material from the excavation of the burial ground lchashen (burial 46, ♂ 20-25 years old) fig. 19. porotic hyperostosis. material from the excavation of the burial ground the black fortress (burial 3/2, ♀ 45-50 years old). a.y. khudaverdyan 51 christensen et al., 1952; møller-christensen, 1961, 1978; andersen and manchester, 1992). mycobacterium leprae prefers cooler areas of the body, leading to infection of mucosal tissues. infection of the nasal area causes skeletal changes, such as loosening of the chondro-osseous junction at the bridge of the nose, which results in the characteristic ‘saddle-nose’ deformity. the nasal septum and hard palate are often perforated, and the anterior nasal spine, nasal aperture margins, and alveolar process of the maxillae are resorbed, the last of which leads to the loss of anterior maxillary teeth (andersen and manchester, 1992; andersen et al., 1994). there is evidence of leprosy in the adults, though one individual from karmir (burial 1) has nasopharyngeal lesions, including significant remodeling of the nasal aperture margins (fig. 14). and 6 individuals from lchashen have nasopharyngeal lesions characteristic of leprosy (figs. 15, 18). non-specific infections lesions on the cranial surface of the skull are indicators of non-specific infection or of trauma but they share similar difficulties with interpretation and identification in adults. endocranial lesions can appear as ‘worm-like’ deposits of new bone, vascular depressions or ‘ ‘hairon-end’ formations. this new bone is macroscopically identical to the ‘woven’ bone deposited during an infection or after trauma. the various appearances of endocranial lesions may indicate different aetiologies: meningitis, epidural haematomas, birth trauma, scurvy, venous drainage problems and tuberculosis, or syphilis (virchow, 1896, in hackett, 1976, p. 44) may cause inflammation or haemorrhage of the meningeal vessels (schultz, 1993). individual 31 exhibits multiple lesions of the outer table of the parietal bones. on the right parietal bone there are several distinct lesions (fig. 16), but two of these are particularly prominent. the surface is composed of smooth, cortical bone, suggesting a healed pathological process. the margins are rolled inwards towards the center of the lesion and fine grooves are present, compatible with the presence of small blood vessels. the inner table shows no evidence of pitting on the endocranial surface. pathological changes observed in the cranial vault (burials 79, 46) include several focal cavitations that penetrate into the diploe but do not affect the inner table. there are also compact bone depressions with grooves (figs. 17, 18). all these cranial vault injuries seem to be a reaction to an inflammatory process that affected the scalp and, consequently, the cortical cranial bone. whether the inflammation was the result of blows, or local or systemic infections, cannot be determined. skeletal indicators of health: systemic stress anthropologists often consider porotic hyperostosis and cribra orbitalia as indicators of iron deficiency anemia, although these markers may have other, less-common etiologies, such as hemolytic anemia and thalassemia (stuart-macadam, 1989, 1992a,b; schultz, 1993, 2001). iron is an important element found in blood, as it assists in oxygen transport to tissues throughout the body. iron deficiency, which can have detrimental consequences, results from a number of factors, including malnutrition, parasitic infection, blood loss, and disease (stuartmacadam, 1989, 1992b). a deficiency in iron produces an associated increase of red blood cell production in the marrow cavities to compensate for the decreased level of oxygen available to tissues. the resulting expansion of the marrow cavities in thin, flat bones such as the cranial and orbital bone causes the external, compact bone to erode, creating a porous surface on the cranial vault (porotic hyperostosis; figs. 7, 18) and in the eye orbits (cribra orbitalia) (stuart-macadam, 1987). the mild forms of this stress indicator (cribra orbitalia) were observed in all age and sex cohorts in the armenian samples. the overall frequency of cribra orbitalia in the lchashen is 8.0%. the prevalence of cribra orbitalia is 28.6% from sarykhan and 9.1% from akynk (movsessian, 1990; movsessian and kotchar, 2001). eight individuals out of 10 from lanjik showed evidence of this marker. seven individuals from the black fortress showed cribra orbitalia. it is also important to note that the temporal increase in prevalence of cribra orbitalia did not correspond to an increase in severity for groups from lanjik and black fortress. in individuals from karmir, criba orbitalia was not revealed as a stress marker. a middle-adult female approximately 50 years old in group black fortress (burial 3/2) was diagnosed with porotic hyperostosis (fig. 18). the external surface of the neurocranium exhibits a two large and irregular areas, lesions that cover most of the parietal bones. manifestations developed on the portions of each parietal bone between the temporal crest and the sagittal suture. in the cranium are several grouped irregular cavities, furrowed by grooves and surrounded by porotic bone. also, 4 adults from the lchashen exhibited porotic hyperostosis (fig. 7) enamel hypoplasias are indicators of growth disruptions during dental development and are visible on teeth as areas of enamel deficiency. most of these hypoplastic defects are oriented horizontally across the tooth, and multiple grooves reflect multiple stress episodes. like porotic hyperostosis and cribra orbitalia, these stress markers are indicative of a childhood condition, as tooth formation is complete before adulthood. the etiological factors implicated in the occurrence of a growth disruption and resulting in a hypoplastic defect, include disease, malnutrition, trauma, and hereditary conditions (goodman and rose, 1990, 1991; hillson, 1996, 2000; roberts and manchester, 2005). however, malnutrition and disease appear to be a far more common cause of these defects, because hereditary defects and localized trauma are relatively rare occurrences (goodman and evidence of infectious diseases in bronze age armenia 52 rose, 1990, 1991). the prevalence of hypoplasia from the black fortress sample is 62% (n = 13) and 50% (n = 10) from landjik. six individuals from sarykha showed evidence of enamel hypoplasias. conclusion the sevan region and shiraksky plain (armenia) was not an ecologically favorable place for human populations. the results of this study further this notion, as there are a number of significant trends for various skeletal indicators of health and lifestyle that suggest the population in armenian experienced stress and biological changes over time. the developing economy—the rudiments animal husbandry—promoted the occurrence and spread of infections among the ancient population of armenia. bad hygienic conditions and dirt should render infections of cumulative influence on skeleton morphology. anthropological examination revealed that the inhabitants in these areas in bronze age and early iron age were subject chiefly to osteomyelitis, facies leprosa, dental diseases such as caries, abscesses, and periodontal disease. osteomyelitis of the skull may follow infection of one of the cranial air sinuses or the middle ear, dental disease, or an open skull fracture. three individuals have evidence of osteomyelitis on the frontal bone. the bony lesion is classically composed of a central sequestrum surrounded by a lytic zone, and then an area of sclerotic response with periosteal new bone peripherally on both inner and outer tables (the involucrum). individuals from the sevan region may have had more chronic infections due to continued exposure to pathogens throughout their lives as well as to traumatic injuries. the unsanitary living conditions, pollution of the water supply, and population density all likely contributed bacterial infections to the population. seven individuals had nasopharyngeal lesions consistent with a diagnosis of leprosy. dental abscesses have an important role in infectious processes, as they are propitious for the development of the bacteria that cause infection, not only in the alveolar bone but also in the rest of the body. dental caries were less severe at sevan (2 individuals from lchashen), although dental abscesses (51 individuals) and antemortem loss (87 individuals) were more prevalent. in contrast, periodontal disease (8/18 adults) and antemortem loss (8/18 adults) of the molars were more prevalent at shiraksky, although the small sample size may be a factor. despite the lack of significant trends in periapical lesions and dental caries, the patterns that emerge indicate that a dietary change took place. however, this change may be associated with food preparation techniques, rather than dietary components. antemortem tooth loss may reflect a softer diet in which there was less abrasion and attrition. it is especially interesting that the prevalence rates for cribra orbitalia are rather similar between the two groups from shiraksky plain. the lack of any trend for porotic hyperostosis and the presence of only the mild form of cribra orbitalia may be due to an overall milder form of anemia in the population. the higher prevalence of enamel hypoplasias may be due to a number of factors, including greater exposure to pathogens (other than parasites) or poorer nutrition (goodman and rose, 1990, 1991; hillson, 2000). poor nutrition in combination with exposure to infectious pathogens would have only heightened this problem, creating periodic episodes of growth arrest, leading to higher rates of enamel hypoplasias. all these data can throw light on aspects of the conditions of the life of people during the bronze age and early iron age in armenia. the forms of infectious diseases illustrated in this article suggest perspectives that hold promise for future dental anthropological studies. acknowledgements many people contributed to this paper. i would like to express my deepest gratitude to my family for all that they have done for me. special thanks are also due to my wonderful teacher, professor vasiliy e. deriabin (moscow) for all of his help, encouragement, and confidence in me. i would like to thank stepаn ter-markaryan (gyumri), hamazasp khachatryan, levon petrosyan (yerevan), and members of the archaeological expeditions for the opportunity to study the human remains from their collections, as well as professor alexander sarafyan (yerevan) for archives of paleopathology. literature cited alekseev vv. 1974. origin of the people of caucasus. moscow: science. andersen jg, manchester k. 1992. the rhinomaxillary syndrome in leprosy: a clinical, radiological and palaeopathological study. int j osteoarch 2:121-129. andersen jg, manchester k, roberts c. 1994. septic bone 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(1973), thompson et al. (1974), mattheeuws et al. (2004) and polder et al. (2004), among others, have reviewed m3 frequencies in contemporary human populations. various speculative ideas have been put forth to explain how a tooth can be congenitally absent and, in particular, why m3s commonly are missing (see, e.g., pindborg, 1970). these mechanistic ideas predate a modern understanding of molecular signaling in tooth development (e.g., matalova et al., 2008), but a short review is informative. as one influential example, ashley montagu (1940) conjectured that tooth agenesis resulted from inadequate space in the developing maxillary dental arch. montagu was focusing specifically on the maxillary lateral incisor that forms on the lateral border of the premaxilla next to the maxillary-premaxillary suture (behrents and harris, 1991). ashley montagu’s contention—which was well reasoned but unsupported by any test—was that tooth size responds to the available space of the supporting bone. ashley montagu speculated that, across eons—as what is now the orthognathic human face diminished in size from prognathic predecessors—tooth sizes (and, especially, size of the maxillary lateral incisors) diminished coincident with increases in pegging and congenital absence of various tooth types. as regards the maxillary lateral incisor that is quite variable (at least in european peoples; harris and rathbun, 1991), ashley montagu concluded that this dental variability is due to the phylogenetic reduction of the premaxilla. ashley montagu sidesteps the question why the canine, the other tooth adjacent to the maxillarypremaxillary suture, is, in contrast, one of the most stable tooth types. he also avoids the problem (except in his introduction) of why the mandibular incisors are not comparably variable, though sizes of the two jaws have necessarily been reduced to similar extents. ashley montagu’s scenario—that reduced bony support leads to reduced tooth sizes—also seems at odds with the third molar located at the distal terminus of the arches also being quite variable even though these molars occur at the other end of the dental ach and form much later than the incisors (haavikko, 1970). it seems that different agents are responsible within each tooth type. sofaer (e.g., 1969, 1979) seems to promote this same idea of inadequate formative space as a general explanation for hypodontia, though this is unsubstantiated by our current understanding of tooth morphogenesis. this conjecture also ignores the three-dimensional dispersions of the developing tooth abstract: third molars (m3s) are congenitally absent (hypodontic) more frequently than any other tooth type. causes of this enhanced variability are poorly understood, but the potential range of absence—from none through four m3s per person—provides the opportunity to examine the permutations of missing m3s within and among ethnic groups. teenage samples of two overlapping populations (1,100 american whites; 600 american blacks) were studied here, with radiographic confirmation of each tooth’s presence in the jaws. roughly 15% of these people are missing at least one m3, but only about 2% of this sample is hypodontic for all four molars. the frequency and severity of missing m3s are significantly higher in whites than blacks. within individuals, correspondence of occurrence is much higher within than between the jaws, but all combinations of m3 hypodontia are positive and significant statistically—implying common underlying developmental influences. while various sorts of data support a genetic influence on the risk of m3 hypodontia, patterns of inheritance suggest a multifactorial rather than a singlegene mode of inheritance. several researchers have promoted a polygenic threshold model, and the history and application of this model are discussed. dental anthropology 2009;22(1):8-17. 9 germs. while it is a graphic metaphor to suppose that a formative tooth bud might be “choked” out of existence due to inadequate bony support, there are no data to support this. instead, cytokines from the dental follicle attract osteoclasts during normal development (marks and cahill, 1983), and these clast cells progressively enlarge the surrounding tooth crypt to accommodate the developing tooth (carlson, 1944). this is readily seen (and palpatable) in infants, where the buccolingual diameters of the primary tooth crypts have enlarged well beyond the incipient bony ridges, and the surfaces of the ridges are scalloped due to these out-pouchings (e.g., van der linden and duterloo 1976). the emergence of teeth into a tight-fitting arcade of teeth as seen in the adult is not indicative of the three-dimensional arrangement of tooth crypts—plus the temporal span during which different teeth form. for example, the canine abuts against the lateral incisor in the adult, but (a) the lateral incisor forms much earlier, when there is plenty of room in the supporting jaws, and (b) when the canines do form, their positions are far apical of the other teeth. molecular biology now makes it clear that a tooth will fail to develop if there is no ectodermal signal to stimulate a site along the underlying mesenchyme to initiate tooth formation (kollar and baird, 1970a,b). this cause of hypodontia seems primarily genetic in nature, but failure of formation also can be affected by the environment. suggestions from animal studies are that tooth buds that fail to reach a critical size will resorb—resulting in hypodontia rather than continuing to develop. likewise, environmental stressors acting at the critical early stages of formation can simply kill off a tooth bud. teratogenic drug actions and irradiation are well-studied examples of this (bruce, 1950; kaste et al., 1998). yet a third mechanism involves a genetic interruption of the cascade of molecular signals leading to tooth formation. this is obvious in the edentates (e.g., armadillos, anteaters; todd, 1918) where there is initial tooth formation, but development ceases early in the bell stage. this interruption also accounts for the “missing teeth” (absence of lateral incisors, canines, and premolars) that is characteristic of mice and other rodents. (see review by peterkova et al. 2006.) the extreme example of this inhibition of tooth development probably is in birds (the class aves), where all modern birds are tooth-less but tooth formation can be reintroduced experimentally (chen et al., 2000; mitsiadis et al., 2006). at an allelic level, it is conceivable that this sort of interruption of molecular events accounts for the variable frequencies of tooth agenesis in humans (e.g., matalova et al., 2008). numerous clinical and physical anthropological studies have reported on the frequencies of missing m3s in humans. the purpose of the present study is to investigate the pattern of missing m3s in some detail within and among individuals in population samples. that is, there are 4 m3s distributed as left-right pairs in the two dental arches, and the issue is how hypodontia is distributed among these 4 sites. this study is restricted to m3s, though there are evident associations among tooth types (davies, 1968; khalaf et al., 2005; harris and clark, 2008). as pertinent examples, alvesalo and portin (1969) and woolf (1971), among others, have documented that the maxillary lateral incisor is more often affected (diminished size, pegged, absent) in individuals with hypodontic m3s versus those with developmentally intact dentitions; hypodontia is not an isolated phenomenon, even among tooth types that form at quite different ages. materials and methods panoramic radiographs (van der linden and duterloo, 1976) of 1,700 adolescents were studied. most (1,100) were american whites, and the rest were american blacks (600), all from clinical records at the college of dentistry, university of tennessee, memphis. subjects were selected with radiographs taken between 12 and 18 years of age. these adolescents were old enough that their m3s would have begun mineralization if they were going to form (rantanen, 1967; harris, 2007), but the adolescents were young enough to well remember having any m3s extracted. it seems obvious that hypodontia has to be documented radiographically, especially for m3s that commonly form but do not erupt into the oral cavity. sample sizes vary among the statistical tests described here because not every tooth’s existence could be documented because of radiographic issues. one intent was to estimate the background frequencies of m3 hypodontia in these two ethnic groups, so subjects with a recognized craniofacial syndrome, including facial clefts, were omitted since they have characteristic—often elevated—patterns of hypodontia (e.g., schalk-van der weide, 1992; ranta, 1983; harris and hullings, 1990). tooth formation can be viewed as a dichotomous event—a tooth has either developed or it is absent. with potentially one m3 in each quadrant, there are 16 permutations of hypodontia. expansion of the binomial shows that there are five m3 groupings, namely (a) all 4 m3s present, (b) four arrangements with 1 tooth missing, (c) 6 arrangements with just 2 teeth missing, (d) 4 arrangements of 3 teeth missing, and (e) one situation where all 4 m3s are hypodontic. in other words, the 16 permutations are arranged in the familiar ratios of 1:4:6:4:1. statistical tests relied on chi-square analysis. statistics were performed using jmp 7.0 (sas, cary, nc). the kappa statistic was calculated as the measure of association (fisher and van belle, 1993). absence of third molars in adolescents 10 results the observed frequency of m3 hypodontia for the total sample (table 1) shows that the distribution is far from random. despite common perceptions that hypodontia of m3 is common, most people experience development of all 4 m3s (86.8%; 1449/1670), whereas congenital absence of all 4 m3s occurred in just 1.6% of the cases. fig. 1 shows that the distribution of severity (i.e., number of congenitally absent m3s) approximates the right-end of a normal distribution, where the frequency decreases as the number of missing m3s increases. the perception that m3s frequently are absent is strongly influenced by the widespread prophylactic extraction of m3s in the late teens (e.g., eklund and pittman, 2001). black-white differences american blacks and whites have been admixing for centuries, though admixture estimates are lower in the southeast than elsewhere in the nation because of harsher social and legal proscriptions (williamson, 1980; davis, 1991). blacks have larger and morphologically more complex teeth (richardson and malhotra, 1975; irish, 1997), and, evidently in an associated manner, discernibly lower frequencies of hypodontia (harris and clark, 2008). stanley garn contended in several of his publications (notably 1977) that tooth size, morphology, tempo of formation, and occurrence (in contrast to congenital absence) are positively intercorrelated features of a common underlying theme in tooth formation, not isolated phenomena—and that these features differ among tooth types controlled, at a primary level, by a tooth’s position in its morphogenetic field. table 2 shows the distributions in each of the arches (sexes pooled). in both jaws, whites have highly significantly higher frequencies of m3 hypodontia, and the source of the significance is primarily due to deficits of bilateral absence in blacks compared to whites (as assessed from the cell chi squares). little is known about hypodontia in other, noncaucasian races; most work has been done on peoples of european extraction where frequencies and the patterning of hypodontia among tooth types probably is not representative of all groups. röse (1906) and hrdlička (1921) each collated data from large series of peoples of diverse races—but with ill-defined criteria and without the benefit of radiography to confirm congenital absence. still, differences in the frequencies of hypodontia are evident in these early studies. population differences in trait frequencies are prima facie evidence for a genetic influence on the risk of hypodontia. sexual dimorphism the data in table 1 were dichotomized into cases t a b l e 1 . d is tr ib u ti on s of m 3 co n ge n it al a bs en ce b y ra ce a n d se x w h it es b la ck s n u m be r m al es fe m al es m + f m al es fe m al es m + f to ta l s am p le m is si n g n % n % n % n % n % n % n % 0 39 6 86 .0 9 50 4 80 .7 7 90 0 83 .0 3 25 4 95 .1 3 29 4 92 .4 5 54 8 93 .6 8 14 48 86 .7 6 1 25 5. 43 49 7. 85 74 6. 83 8 3. 00 11 3. 46 19 3. 25 93 5. 57 2 29 6. 30 41 6. 57 70 6. 46 3 1. 12 10 3. 14 13 2. 22 83 4. 97 3 5 1. 09 12 1. 92 17 1. 57 1 0. 37 0 0. 00 1 0. 17 18 1. 08 4 5 1. 09 18 2. 88 23 2. 12 1 0. 37 3 0. 94 4 0. 68 27 1. 62 su m s 46 0 62 4 1, 08 4 26 7 31 8 58 5 1, 66 9 e.f. harris 11absence of third molars in adolescents without m3 hypodontia and cases missing one or more m3s. this showed that hypodontia is significantly more common in girls than boys in whites (χ2 = 5.3; df =1; p = 0.02). the source of significance (based on cell chi squares) is primarily due to the comparative deficit of hypodontia in males. 14% of males exhibit agenesis of one or more m3s, compared to 19% of females. the overall frequency is appreciably lower in american blacks (ca. 6% vs. about 16% in whites) and, with the smaller sample size of 600, the sex difference is not significant here (χ2 = 1.8; df = 1; p = 0.1850). if the present frequencies hold, a sample size roughly three times larger (ca. 2,000) would be needed to achieve statistical significance in blacks. in addition to the greater frequencies of m3 hypodontia in females, fig. 2 shows that severity—as measured by the number of missing m3s—also is greater in females than males. this shift towards greater expression in females is more obvious in whites because of their greater incidence of m3 hypodontia overall. arcade effects there are positive, statistically significant associations for m3 hypodontia between all four m3s taken pairwise; the matrix of kappa correlations (table 3) based on the total sample shows that left-right symmetry is highest (kappa ~ 0.7) within each arch, and the inter-arch associations are appreciably lower (kappa ~ 0.3), but correlations within and between hemispheres seem equivalent. hierarchically, the symmetry between sides is much higher than between arches, but whether the association between the arches is taken between the same or opposite quadrants seems immaterial. a related point is that asymmetric occurrence is relatively uncommon. m3 status in one quadrant strongly predicts the same status in the antimeric site. this is anticipated since our understanding is that the same genotype affects tooth development in the left and right quadrants, with effectively the same environment in each to achieve a tooth’s phenotype. dental researchers have sought evidence for laterality or sidedness, primarily using data on crown dimensions. documentations of laterality are few and scattered among samples (e.g., harris, 1992; townsend et al., 1999). the bulk of leftright asymmetry is expressed as random (fluctuating) asymmetry, at least with regard to size. figure 3 arborizes the frequencies of hypodontia by tooth type and, thereby, shows the dependencies (statistical associations) between the arches. an obvious “dose-dependent” relationship from among several of the associations is this: when both upper molars are congenitally absent, just 50% of the two mandibular molar molars are present. when just one upper molar is present, the frequency of the two lower molars being table 2. frequencies of m3 hypodontia in american blacks and whites whites blacks both one both both one both chi statistic absent absent present absent absent present df square1 maxilla % 5.0 4.0 90.9 1.7 3.2 95.1 n 56 45 1010 10 19 561 2 12.6 mandible % 4.5 3.1 92.5 1.2 1.5 97.3 n 74 51 1534 7 9 572 2 17.8 1both x2 values are highly significant (p < 0.0001) because m3 hypodontia is more common in whites than blacks. 0 1 2 3 4 0 20 40 60 80 100 p e rc e n t o f s a m p le number of missing m3s 86.8 5.6 5.0 1.1 1.6 fig. 1. percentage distribution of m3 hypodontia in the total sample. 12 absent rises to 70%. and, when neither upper m3 is absent, the frequency of both lower molars being agenetic rises to a high of 94%. side effects sidedness is the interesting situation where there is preferential laterality: does absence of a tooth on one side influence absence of the same tooth in the opposing arch? the informative cases are those where either the left or right molar is absent in the maxilla and likewise (unilateral absence) in the mandible. unfortunately, cases of unilateral congenital absence in both dental arches are uncommon, just 7 cases in the 1,670 individuals where all 4 m3s could be scored. these 7 cases were equally distributed (3:4) as to arrangements where the ipsilateral tooth (same hemisphere) was missing in the two arches versus where the contralateral tooth (opposite hemisphere) was absent. at least with these few informative cases, there is no suggestion of sidedness. another way of viewing laterality is simply whether m3 is more common on one side of the mouth than the other. the maxillary left-right distribution of unilateral presence is 33 (left only) compared to 32 (right only), which is indistinguishable statistically from a random spread of 50:50. in the mandible, the left-right distribution of congenital absence is 27 (left only) compared to 34 (right only). this does not depart from a 50:50 chance occurrence (p = 0.53). congenital absence of m3 is, then, equally distributed between sides. discussion hypodontia in itself suggests a phenotypic dichotomy: the tooth either is present or absent. features of hypodontia, notably the increased frequencies among relatives of affected individuals (grahnén, 1956; brook, 1984), imply a hereditary basis for the condition, though the mode of transmission is not simple (mendelian). differences in population frequencies among inbred strains of laboratory animals (e.g., grüneberg, 1952; chai and chiang, 1962; sofaer, 1969) and among human groups (e.g., ashley montagu, 1940; polder et al., 2002; harris and clark, 2008) likewise favors some genetic basis for hypodontia. sex differences in rates of occurrence (typically with the frequency and severity of agenesis being greater in females) is a third indicator that genes influence a person’s risk (egermark-eriksson and lind, 1971). the dramatic effects of some major genes, notably the suite of genes causing forms of hed (hypohidrotic ectodermal dysplasia), might also be mentioned here, but these phenotypes are characterized by oligodontia or, even, anodontia, so they do not stem from the same alleles leading to the absence of a single or just a very few teeth as occurs in most people with hypodontia (schalk-van der weide, 1992). elucidation over the past few years of specific molecular signaling factors that predispose for hypodontia, such as pax 9, msx 1, msx 2, and others, greatly strengthens the argument for a genetic basis of congenital absence (e.g., mostowska et al., 2003; viera, 2004; larmour et al., 2005). these few first molecular factors to be identified are, predictably, those with clear-cut effects on the phenotypes—where affected individuals commonly are missing multiple teeth. analytical refinements (and larger sets of family data) will lead to documentation of genes with subtler but probably more common frequencies in the general population. work to date shows that deleterious alleles (pax 9 and so forth) enhance the risk of hypodontia, but they do not fully determine it, and the variable expressivity among cases likely is due to (a) the individual’s genetic background against which these alleles are expressed and (b) environmental conditions that modulate expression. quasicontinuous model hypodontia as expressed in most humans (with one or a few missing dental elements) has no known etiology. it is, however, common enough to warrant the attention of many dental researchers. a popular model of inheritance that accounts for the observed phenotypic distributions of the condition is quasicontinuous inheritance. the supposition is that some indefinite number of genes collectively contribute to trait expression (where “expression” here is congenital absence). this is the common polygenic model (e.g., falconer, 1989), but with a threshold (fig. 4). the threshold is toward the lower end of the supposed underlying genotypic array. for the bulk of the population (that is above the threshold) teeth are present. it is in those comparatively few cases who fig. 2. the frequencies of the congenital absence of m3 (all expressivities combined) by race and sex. m3 hypodontia is more common in american whites than blacks, and more frequent in girls than boys in each race, though the extent of sexual dimorphism is appreciably higher in whites, perhaps because the overall incidence is higher in whites. e.f. harris 0 1-4 0 20 40 60 80 100 p e rc e n t o f s a m p le number of missing m3s 86.1 80.8 95.1 92.5 13.9 19.2 4.9 7.6 white males white females black males black females 13absence of third molars in adolescents are below the threshold that hypodontia occurs. there is an interesting but tangled history of this model. many physical anthropologists, particularly those with interests in skeletal biology, attribute it to the work of hans grüneberg (1950, 1952) who marshaled the quasicontinuous model (qcm) as an explanation for the numerous minor skeletal variants he studied in mice, such as accessory foramina, ossicles, and other morphological features, that occur in some animals but not others. the utility of these “discrete” (i.e., present or absent) skeletal features for phenetic studies of human skeletal series was popularized by a. c. berry and r. j. berry (e.g., 1967, 1968, 1974). grüneberg’s work in turn rested on the seminal studies of sewall wright in the 1930s. wright (1934a,b) explored the inheritance of the number of digits on the hind feet of guinea pigs, which normally have 3 digits but may have 4, and attributed the occurrence of 4 toes to the guinea pig’s genotype exceeding what he termed a “physiological threshold.” indeed, his figure 1 (1934b, p. 544) depicts the presumed underlying polygenic model as a normal curve overlying two successive thresholds, a lower one, where poorly-formed (“vestigial”) 4th toes occur, and a higher one, where the 4th toe is eumorphic. this development of a two-threshold scheme is precisely what was exploited later by reich and others (reich et al., 1972; corbett et al., 2004) to provide practical statistical tests for distinguishing between single-gene and polygenic models of inheritance. while wright did not formalize the qcm, he described its major features during his various breeding experiments. denys falconer (1965) elaborated the assumptions and statistical expectations of the qcm. falconer described how heritability (v additive / v total ) of a trait could be estimated from trait frequencies. however, this requires family data (information on relatives of known degrees of biological relatedness). heritability cannot be calculated from samples of cases without known relationships, so this useful aspect of the qcm generally has been ignored in skeletal biological studies, but with some noteworthy exceptions: saunders and popovich (1978) recorded minor skeletal variants from radiographs of siblings enrolled in the burlington growth study. sjøvold (1984, 1996) analyzed skulls of europeans where genealogical information had been preserved. cheverud and colleagues (e.g., mcgrath et al., 1984; richtsmeier et al., 1984) used the unique setting of the island of cayo santiago (where genealogical affinities of most monkeys is known) to estimate heritability of several nonmetric bony features in macaques. the work of carter (notably 1969) warrants mention here because (a) he demonstrated the applicability of a threshold model for many common diseases (e.g., pyloric stenosis, diabetes mellitus, spina bifida cystica, and others), which did much to familiarize the health care community with this quasicontinuous model and table 3. correlation coefficients (kappa) between the four third molars taken pairwise1 upper upper lower left right left upper 0.66 right (0.0400) lower 0.31 0.33 left (0.0437) (0.0439) lower 0.30 0.31 0.71 right (0.0442) (0.0444) (0.0356) 1values in parentheses are the standards errors of the estimates; all 6 correlations are highly significantly different from zero (p < 0.0001). none present one present both present none present one present both present none present one present both present 0 10 20 30 40 50 60 70 80 90 100 percent of sample 94.2 3.1 2.7 70.3 10.9 18.8 50.8 9.0 40.3 both max. present one max. present neither max. present m an di bu la r st at usm ax ill ar y st at us fig. 3. dependence between arches in the occurrence of m3s. (top) when both maxillary m3s are present, 94% of cases have both mandibular m3s present. (middle) when just one of the two maxillary molars is present, the frequency of both lower m3s being present drops to 70%. (bottom) when both maxillary m3s are congenitally absent, the frequency of both lower m3s being present is just 40%. these associations indicate nothing about cause and effect; the same dependencies are found if the lower molars are taken as the predictive variable. 14 (b) he listed several criteria that, when met, can be very suggestive of a polygenic threshold model. while largely beyond the scope of this paper, it is informative to note that james (1971) pointed out that too many parameters need to be estimated than can be obtained from a qcm with one threshold. but, adequate parameters are available if two thresholds are supposed in the model, and james worked with ted reich (e.g., reich et al. 1972; corbett et al. 2004) to develop tests that can distinguish between inheritance due to a singlegene model versus a polygenic model. suarez and spence (1974) applied a basic form of this approach to the hypodontia family data collected by grahnén (1956), concluding that a polygenic threshold model fit the data appreciably better than expectations of the effects of single gene. qcm and hypodontia davies (1968), sofaer (1969), bailit (1975), and chosack et al. (1975), among others, alluded to the qcm fitting observations seen in population samples, but brook (1984) was the first to seriously develop the qcm to hypodontia (and, at the other, complementary extreme, hyperdontia). brook emphasized the developmental interrelationships between hypodontia and tooth size. there also is a well-documented relationship between hypodontia and crown sizes of the remaining teeth; people in the population who do not have hypodontia have statistically larger teeth than those with congenital absence (garn and lewis, 1962; garn et al., 1962, 1963, 1970). conversely, diminished crown sizes and microdontia are more common in those with hypodontia than in those with full complements of teeth. these clinical results are duplicated in laboratory animals (grüneberg, 1950, 1952; self and leamy, 1978). the greater the extent of hypodontia, the greater the size reductions and the greater likelihood of microdontia (with associated missing cusps and simplified morphologies of the remaining teeth). numerous studies of european groups have found higher frequencies of hypodontia in females than males (reviewed in egermark-eriksson and lind, 1971). these several associations suggest that hypodontia has dentition-wide systemic effects, which is predictable since teeth form as repetitive elements (a meristic series; bateson, 1894) using the same regulatory mechanisms controlled by the person’s genotype (kettunen and thesleff, 1998; jernvall and thesleff, 2000). grüneburg (1952) documented differences in the frequencies of third molar hypodontia among inbred strains of mice. mice with larger teeth had lower frequencies of m3 hypodontia than strains with smaller teeth. the same relationship is evident in humans, where african americans (with large teeth) exhibit m3 hypodontia infrequently compared to american whites with smaller crown sizes and higher frequencies (and greater severities) of m3 hypodontia (harris and clark, 2008). hyperdontia (supernumerary teeth) is, in contrast, more common in males (e.g., stafne, 1932; khalaf et al., 2004). this collage of interrelated features recently has been extended by uslenghi et al. (2006) who showed that hypodontia is associated with slowed tooth development (also see garn et al. 1961). liability of hyperdontia po pu la tio n di st ri bu tio n of g en ot yp es females males liability of hypodontia microdontia congenital absence macrodontia supernumerary teeth difference between means fig. 4. schematic of the quasicontinuous model (modified from brook, 1984). there is an underlying genotypic range in a population that influences a person’s risk for hypodontia (left extreme) and hyperdontia (right extreme). sex-specific distributions are shown here to reflect the greater risk of congenital absence in women versus the greater risk of supernumerary teeth in men—at least in peoples of european extraction. sexual dimorphism appears to be lower in peoples of subsaharan extraction. the vertical bars are depicted as broken lines since a person’s genotype can be modulated in either direction by the environment. e.f. harris 15absence of third molars in adolescents overview the present study assessed the phenotypic patterns of third molars (m3) congenital absence in 1,700 teenagers composing a contemporary cohort of american blacks and whites from the southeast united states. • there is no difference by arcade, but agenic m3s are significantly more common in females than males and in american whites compared to american blacks. • no evidence of sidedness (preferential absence on one side) could be discerned, and asymmetry (unilateral occurrence) is fairly uncommon versus symmetric presence or absence. • congenital absence of one m3 is highly predictive of other missing m3s, suggesting common developmental associations that probably are modulated by the person’s genetic background. • while genes with rather severe effects on congenital absence have been documented, most cases of hypodontia are of unknown etiology, although population distributions are in concert with a quasicontinuous model of inheritance (also termed a polygenic threshold model). 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49 dental anthropology 2021 │ volume 34│ issue 01 lingually shoveled incisors, an anatomical feature first described by hrdlička (1920, 1921), are a salient characteristic of the phenomenon now termed sinodonty, a suite of dental characters common between native american and east asian populations, but occurring at much lower frequencies in non-sinodont populations (turner, 1971, 1976, 1986, 1990; see also mizoguchi, 1985; scott & turner, 1988; stojanowski et al., 2013; scott et al., 2018). this disjunct geographical distribution has historically provided strong indirect support for hypothesized old world origins of new world human populations (e.g., turner & bird, 1981). anatomically, the condition of sinodonty refers primarily to the presence of posteriorly shoveled incisors, single-rooted upper premolars, and threerooted lower molars, and is strongly heritable (hanihara et al., 1974; blanco and chakraborty, 1976), but is also likely to be polygenic in origin. genetically, presence of the allele edar v370a significantly influences the condition of incisor shoveling along with a variety of other ectodermic features, including increased thickness of scalp hairs (see bryk et al., 2008; fujimoto et al., 2008; chang et al., 2009; kimura et al., 2009). increased tooth crown size also associates with edar v370 (kimura et al., 2009; park et al., 2012), and its greater expression in mice furthermore reduces mandibular length (adhikari et al., 2016). pleiotropic effects of this allele are thus substantial. positive selection on edar v370a has been intense in humans, consistent with its very high frequencies in east asian and native american populations relative to other groups (see sabeti et al., 2007; bryk et al., 2008; kamberov et al., 2013; hlusko et al., 2018). demic modelling based on extant frequencies of edar v370a in primarily asian populations (kamberov et al., 2013) indicates geographical origins of the allele in central and north china, within a region broadly congruent with the extensive alluvial plains of the yellow, huai, and a morphofunctional hypothesis for selection on edar v370a and associated elements of sinodonty robert dudley 1,2 * 1 university of california, berkeley 2 smithsonian tropical research institute abstract the phenomenon of sinodonty refers to a suite of dental characters shared between east asian and native american populations, and most prominently to the presence of shoveled incisors. although this syndrome is a conspicuous aspect of dental differentiation among extant human populations, elements of which have been recent subject of detailed genetic analysis, adaptive consequences of shoveled incisors and related features remain unclear. here, i hypothesize that many of the associated differences in dentition (along with reduction in mandibular length and increases in salivary gland branching) arose in parallel with the opportunistic consumption of wild rice and millet in central and northern china, respectively, and with their subsequent domestication in the upper paleolithic. more efficient mastication and digestion of plant grains (and of other starchy foods obtained via broadspectrum foraging) would potentially have been enabled by these traits, yielding greater rates of nutritional intake as wild crops were progressively domesticated. this functional hypothesis, although not mutually exclusive relative to other proposed selective factors, matches the estimated timeline in china for both origin and time to fixation of the associated allele (edar v370a), and is consistent with chronic energetic gain and fitness benefits independent of any assumptions for concurrent climatic conditions. *correspondence to: robert dudley department of integrative biology university of california, berkeley; smithsonian tropical research institute balboa, republic of panama wings@berkeley.edu keywords: agriculture, china, diet, edar v370a, shoveling 50 dental anthropology 2021 │ volume 34│ issue 01 yangtzi (changjiang) rivers. this demic model also places time of origination for the allele between ~40,000 and ~13,000 years bp, with a modal value of 35,300 years bp. a parallel approach to allele age using maximum likelihood estimation for data from modern han chinese places origination between ~38,000 and ~35,000 years bp (see kamberov et al., 2013). finally, the modal value for fixation time of edar v370a has been estimated (using haplotype data from 23 individuals of chinese descent) as 10,740 years bp (bryk et al., 2008). these estimates for origination and fixation of edar v370a within east asia are recent relative to the age of our species, and are also suggestive of powerful selective forces at play over a short time interval. because scalp hair density is increased by edar v370a, various authors have suggested that thermoregulatory and water balance would be influenced by this morphological change, particularly in the cooler and drier climates of the upper paleolithic (see yuan et al., 2004; chang et al., 2009). an alternative hypothesis links increased eccrine (sweat) gland density to greater evaporative heat loss in a humid monsoonal climate (kamberov, et al., 2013). mammary duct density also increases in the presence of edar v370a, raising the possibility of enhanced maternal milk delivery and associated fitness benefits (hlusko et al., 2018). concomitant changes in dentition may thus have derived pleiotropically from selection on other traits. however, sinodonty by definition refers to tooth anatomy, which broadly reflects diet in mammals (ungar, 2010; pineda-munoz et al., 2017). it is therefore parsimonious to consider dietary shifts concurrent with the rise of edar v370a and associated elements of sinodonty that may have been the target of natural selection. in particular, the timeline for fixation of this allele, along with its inferred geographical region of origin, correspond well to archaeological data that indicate foraging of wild rice and millet in china, along with their subsequent domestication. the origins of prominent features of sinodonty, in other words, correlate temporally with a major dietary shift associated with the emergence of cultivated crops in east asia. i hypothesize that this specialized human dentition, along with other related phenotypic effects of edar v370a, were advantageous for the mastication and subsequent digestion of sympatric wild grains, and thus yielded energetic advantage during the extended process of crop domestication. timeline for rice and millet domestication in china domesticated rice in east asia refers to a single subspecies (oryza rufipogon ssp. japonica) derived from a wild ancestor, whereas millet refers to two species domesticated from different grass genera (broomcorn millet: panicum miliaceum; foxtail millet: setaria italica). phylogenetic reconstruction places rice domestication in china at ~13,500–8200 bp (molina et al., 2011), a range congruent with corroborative archeological evidence (see liu et al., 2007; gross & zhao, 2014). similarly, archeological finds are consistent with the domestication and cultivation of millet nearly 10,000 years ago (lu et al., 2009; yang et al., 2012; bestel et al., 2014). foraging on wild grains would have necessarily preceded their domestication. for example, processing with grinding stones of wild grass seeds (including possibly ancestral millets) occurred as early as ~24,000 years bp (see liu et al., 2013; liu et al. 2018). the oldest known sites for pottery in china date to ~20,000–10,000 years bp, possibly marking the emergence of agriculture (see wang & sebillaud, 2019). starchy foods more generally became increasingly prevalent through the upper paleolithic in china, as suggested by increased usage of nuts, beans, and tubers (see liu et al., 2013). archeological records cannot capture in detail the spectrum of foraging and cultivation behaviors carried out over millennia, and across a geographical mosiac, during the process of crop domestication (see fuller et al., 2014; larson et al., 2014). nonetheless, the overlap between estimated timelines for the origin and fixation of edar v370a, and for the domestication of rice and millet, is substantial (figure 1). functional consequences of sinodonty shoveled incisors and related features of sinodonty may influence chewing dynamics and masticatory efficiency. it has long been suggested that shoveling increases tooth strength and resistance to bending (see hrdlička, 1921; dahlberg, 1963). specific effects of incisor shoveling and changes in premolar and molar root numbers are unknown for mastication, which is associated with diverse features of jaw kinematics (see ross et al., 2012). also relevant is the substantial reduction in mandibular length associated with expression of the edar allele (by 5–10% in mice; see adhikari et al., 2016). in human agriculturalists, mandible dimensions are reduced relative to non-agricultural populations, consistent with relaxation of masticatory demand (see von cramon-taubadel, 2011; noback & 51 dental anthropology 2021 │ volume 34│ issue 01 harvati, 2015; katz et al., 2017). paleontological data are not available to document the tempo of mandibular reduction across the rice and millet domestication sequence in east asia, but a causal link with edar v370a cannot be excluded. interestingly, another consequence of enhanced edar expression in mice is to increase branching of adult salivary glands (by ~25%; chang et al., 2009), which may in turn increase rates of saliva production and thereby facilitate starch digestion in the mouth (valdez & fox, 1991). this mechanism would provide a direct linkage between anatomical changes associated with edar v370a expression in humans, and advantageous physiological outcome as starchy crops were domesticated. an analogous argument was advanced by hlusko et al. (2018) relative to increases in mammary duct density and lactation; such effects on gland density could moreover be complementary in some contexts (e.g., greater energy uptake would enable increased milk production), and would pertain independently of any specific climatic conditions. pleiotropic changes in teeth, mandibular bone, and salivary gland density resulting from edar v370a can therefore influence human nutritional physiology in diverse ways. discussion and conclusions various alleles alternative to edar v370a may contribute to tooth shoveling and other features characteristic of sinodonty, and do not necessarily correspond to specific dietary adaptations. prominent incisor shoveling in neanderthals, for example, well precedes the origin of edar v370a, and does not associate with increased masticatory stresses (clement et al., 2012). similarly, a 3-rooted lower second molar has been described from a denisovan mandible from western china, dated at ~160,000 bp (bailey et al., 2019), although identification of this tooth has been challenged (see scott et al., 2020; bailey et al., 2020). the age of this specimen nonetheless well precedes the 38,000–35,000 bp estimated origination time for edar v370a (see kamberov et al., 2013), and its features presumably derive from different genetic origins. incisor shoveling in native americans likely derives genetically from their eurasian source populations in northeastern siberia (see flegontov et al., 2019; mathieson, 2020), but the oldest known human dentition from this latter region (~31,000 bp) is unfortunately incomplete with unknown occurrence of sinodonty (see sikora et al., 2019). the increased incidence of shoveling in down syndrome figure 1. timelines for estimated origin and fixation of edar v370a, and for relevant archaeological data and estimates of crop domestication. dashed lines indicate approximate temporal ranges; see text for details and relevant citations. 52 dental anthropology 2021 │ volume 34│ issue 01 (see cohen et al., 1970) is not yet characterized at the allelic level. finally, an additional edar variant is found in south china and southeast asia, but has not apparently been the target of positive selection (riddell et al., 2020). a pressing empirical need to evaluate any functional hypothesis relating to sinodonty and to effects of edar v370a is to obtain a quantitative assessment of tooth and mandibular variation through time in east asia. changes in dentition and mandibular dimensions across the paleolithic in china are not currently available, although there was a substantial reduction in mandibular dimensions from the neolithic through the bronze age (li et al., 2012). incisor shoveling incidence in western european populations (which is low relative to that found in east asia) has declined since the neolithic (brabant, 1971), a trend which may derive from genetic drift. quantitative measurements of tooth morphology (e.g., carayon et al., 2018) would enable better characterization of the shoveling phenotype and associated variation through time and among human populations, along with finite-element modeling of tooth bending mechanics. similarly, consequences of changes in mandibular geometry can be inferred from mechanical modeling, although functional outcomes can be complex and not necessarily predictable from linear data (sella-tunis et al., 2018), to which end three-dimensional structural modelling using finite-element analysis would be appropriate (see morales-garcía et al., 2019). multiple hypotheses pertain to the possible selective advantages of edar v370a, and none of these are mutually exclusive. recognition of the temporal correlation between allele age and the timelines for wild grain consumption and domestication in east asia, however, provides a linkage between diet and nutritional gain during the transition to agriculture. worldwide, this transition has been associated with diverse changes in human behavior and morphological features, and is suggestive of powerful selective forces at play. for example, an allele for a highly active form of alcohol dehydrogenase originated in central china in parallel with rice domestication, prompting speculation as to increased dietary exposure to ethanol derived from carbohydrate fermentation (peng et al., 2010). the pleiotropic effects of edar v370a are multifaceted, and unifactorial explanations for associated selective forces are likely to be incomplete. nonetheless, chronic energetic benefits concurrent with grain domestication in east asia have not previously been envisioned for this allele, and may have been of considerable advantage. acknowledgments i thank professor li liu and two anonymous reviewers for helpful comments on the manuscript. references adhikari, k. et al. 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(2020). limited evidence for selection at the fads locus in native american populations. molecular biology and evolution, 37, 20292033. mizoguchi, y. (1985). shovelling: a statistical analysis of its morphology. tokyo: university of tokyo press. molina, j. et al. (2011). molecular evidence for a single evolutionary origin of domesticated rice. proceedings of the national academy of sciences usa, 108, 8351-8356. noback, m.l., & harvati, k. (2015). the contribution of subsistence to global human cranial variation. journal of human evolution, 80, 34-50. park, j.-h. et al. (2012). effects of an asian-specific non-synonymous edar variant on multiple dental traits. journal of human genetics, 57, 508514. peng, y. et al. (2010). the adh1b arg47his polymorphism in east asian populations and expansion of rice domestication in history. bmc evolutionary biology, 10, 15. pineda-munoz, s., lazagabaster, i.a., alroy, j., & evans, a.r. 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(1991). interactions of the salivary and gastrointestinal systems. i. the role of saliva in digestion. digestive diseases, 9, 125132. von cramon-taubadel, n. (2011). global mandibular variation reflects differences in agricultural and hunter-gatherer subsistence strategies. proceedings of the national academy of sciences usa, 108, 19546-19551. wang, l., & sebillaud, p. (2019). the emergence of early pottery in east asia: new discoveries and perspectives. journal of world prehistory, 32, 73110. yang, x., wan, z., perry, l., lu, h., wang, q., zhao, c., li, j., xie, f., yu, j., cui, t., wang, t., li, m., ge, q. (2012). early millet use in northern china. proceedings of the national academy of sciences usa, 109, 3726-3730. loch et al. 2014.1 3 dental anthropology 2014 │ volume 27 │ issues 01 and 02 in memoriam: julius (jules) august kieser (20 december 1950 – 10 june 2014) jules kieser was born in pretoria, south africa, in 1950. jules’ parents moved to johannesburg where he enrolled at the university of the witwatersrand. he obtained a bsc in anatomy in 1971, followed by a bachelor of dental sciences in 1975. jules then practiced dentistry in the outback of south africa, london and johannesburg, with his wife glynny working as his assistant. in 1989, jules received his phd from the university of the witwatersrand, working under phillip tobias on the dentition of the lengua indians of paraguay. after holding positions of consultant and honorary lecturer, jules was appointed as professor and reader of craniofacial biology at the university of the witwatersrand in 1991. in 1996, jules and his family emigrated from south africa to new zealand, where he was appointed chair in oral biology and professor in the department of oral sciences and orthodontics at the university of otago. in 2001 he was awarded his dsc from the university of the witwatersrand. in otago, jules held positions as chair and professor at the department of oral sciences and orthodontics, and associate dean for research in the division of health sciences. he was the inaugural director of the sir john walsh research institute and associate dean for research at the faculty of dentistry. since his arrival in new zealand in 1996, he lectured oral biology, biomedical sciences and forensic biology to many dental surgery, oral health and forensic science students. he was regarded widely as a positive and enthusiastic lecturer, with a relaxed, humorous and engaging style of teaching. jules had a prolific research record, having published 196 journal articles and four books. his research interests were broad and spanned across diverse disciplines such as dental anthropology, craniofacial biology and biomechanics, forensic biology and dental education. in particular, jules’ contributions to the fields of human odontometrics, dental asymmetry and development instability, and many other areas of craniofacial biology were valued by dental anthropologists worldwide. jules studied the dentition of modern human populations, of early archaeological and fossil human remains, and of diverse animals such as crocodiles, primates, tuataras and dolphins. he was instrumental in the development of forensic biology research in new zealand and his practical expertise in forensic odontology was fundamental in the identification of the victims of the 2004 thai tsunami and 2011 christchurch earthquake in new zealand. he received a new zealand special services medal for his service during the thai tsunami and a new zealand commissioner of police citation for his work in christchurch. other awards included fellowships of the galton institute of london (1994) and linnean society of london (1995), an ad hominem fellowship in dental surgery from the royal college of surgeons of edinburgh (2004), the alan docking award for distinguished research in dentistry (2008), a fellowship of the faculty of maxillofacial pathology of the royal college of pathologists of australasia (2013), a fellowship of the chartered society of forensic sciences (2014), and a wits distinguished scholar and a wits-carnegie alumni diaspora fellowship (2014). jules was a keen and experienced scuba diver and had diving as one of his main hobbies. he held a 3rd dan karate black belt and had been a keen martial artist. jules was also an eager rugby enthusiast. he enjoyed gardening, taking his dogs for bush walks and observing and attracting native birds to his property, especially new zealand wood pigeons. jules had a substantial library, including many diverse subjects outside his work interests. he was particularly interested in world history, war and strategy, and the evolution and development of civilizations. he enjoyed trying different varieties of chocolate and wine from other parts of the world during his multiple travels overseas. jules and glynny had four children: annie, jj, daniel and david, who, from very early days, had always been involved in his work and research. as a result, many of his students and colleagues were also friends of his family. 4 dental anthropology 2014 │ volume 27 │ issues 01 and 02 jules will be remembered as a very supportive and influential mentor and outstanding role model. his warm and positive personality was combined with a sharp mind and generous heart. jules always fostered collaboration instead of competition; and always saw the development and advancement of the careers of his students and peers as beneficial to his own career development. he was a very humble and humane person, and a skilled master of social interactions. his contributions and his influence on his colleagues went way beyond the scientific and academic environments. we will miss this exceptional friend and colleague greatly and he will be always remembered as an example of someone we should all strive to emulate. carolina loch¹, grant townsend² and christopher dean³ 1sir john walsh research institute, faculty of dentistry, university of otago, new zealand 2school of dentistry, university of adelaide, south australia 3cell and developmental biology, university college london, uk 13 dental anthropology 2023 │ volume 36│ issue 01 morphogenetic fields and variation in deciduous tooth crown size john r. lukacs* department of anthropology, university of oregon this study analyzes variation in deciduous tooth crown dimensions within the context of morphogenetic developmental fields. do patterns of variation in deciduous odontometic data conform to expectations predicted by morphogenetic fields (mgf) in a manner analogous to morphometric variation in permanent teeth? morphogenetic developmental fields have been proposed to explain morphometric attributes of meristic dental elements in the post-canine teeth of mammals (butler, 1939). the concept was initially adapted to explain variation in expression of morphological attributes of the permanent dentition of modern humans by dahlberg (1945, 1950, 1951). more recently the morphogenetic field concept in the human dentition has been integrated with clone and homeobox code models of dental development to better understand anomalies of tooth number and size (townsend et al., 2009). a field-like mechanism proposed to predict the size of mammalian and hominin teeth is known as the inhibitory cascade, an activator–inhibitor mechanism that affects relative tooth size (evans et al., 2016; kavanaugh et al., 2016). analysis of patterns of variability in crown dimensions of permanent teeth in humans and non -human primates were summarily critiqued by kieser (1990), who reviewed approaches to odontometric variability giving attention to evidence of developmental and occlusal influences, group variation theory, and coefficients of variation. he concluded that the exact causes for patterns of metric variability in permanent teeth are poorly understood. analyses of deciduous dental variability are far fewer with significant assessments by harris (2001; harris and lease, 2005) for mesiodistal data and by riberio et al. (2012) for mesiodistal (md) and buccolingual (bl) diameters, crown height, and intercuspal distances of same-sex monoand abstract does variation in deciduous tooth crown size and variation agree with expectations predicted by morphogenetic fields (mgf) as documented for morphometric attributes of permanent teeth? published literature on deciduous tooth crown size permits analysis of a large dataset. are expectations of mgf theory evident in size and patterns of variation within and between deciduous tooth classes? thirty-five reports of deciduous tooth crown size have a global distribution, are ethnically diverse, and geographically widespread. analysis centers on mesiodistal (md) and buccolingual (bl) dimensions, crown areas (ca), coefficients of variation (cv) and rank order of variability across populations and dental arcades. mean crown size, cas and cvs follow expectation: a) udi1is larger and less variable than udi2, b) a gradual decline in mean cvs from dc to dm2 is evident, c) in rank order of decreasing cv dm2 is the least variable, and incisors are most variable. the udi1 and dm2s exhibit attributes of key teeth. in size, measures of variability, and rank order variation across teeth, results are consistent with expectations based on mgfs in permanent teeth. this confirms the likely existence of morphogeneticlike fields in deciduous teeth during dental development. the diverse groups and different modes of analysis ensure confidence in the results that may have value for clinical purposes and evolutionary studies. *correspondence to: john lukacs university of oregon e-mail: jrlukacs@uoregon.edu keywords: coefficient of variation; tooth size; deciduous dentition; primary teeth; odontometry 14 dental anthropology 2023 │ volume 36│ issue 01 di-zygotic twin pairs. an atlas depicting the development and eruption of deciduous and permanent dental elements clarifies the ontogenetic relationship of the two dentitions (alqahtani et al., 2010; https://www.qmul.ac.uk/dentistry/atlas/). interestingly, dahlberg (1945, 1951) did not define fields within the primary dentition and, without any comment, he added a premolar field to butler’s (1939) three-field paradigm for permanent teeth (townsend et al., 2009: s35). this observation was reiterated seven years later, “neither butler nor dahlberg commented specifically on the application of dental field theory to the deciduous dentition” (hemphill, 2016). while generally correct, these comments overlook the many instances in which patterns of metric variation in deciduous tooth crown dimensions have been interpreted to be consistent with expectations of morphogenetic field theory. this opinion may be stated simply with little elaboration, for example, “the variability in the md and bl measurements follows the field concept” (axelsson & kirveskari, 1984: 343). before this, hanihara (1974) used factor analysis to identify influences controlling variation in deciduous tooth crown size in four groups (japanese, australian aboriginals, native american pima, and caucasians) and found three factors influencing size and shape. the tendency for the second molar to be less variable in size than the first in a dominican sample was noted to be in accord with the field concept which considers deciduous second molars as anterior members of a molar tooth field and therefore particularly stable in their morphology (garcia-godoy et al., 1985). farmer & townsend (1993: 681) note that although distinct morphogenetic fields have not been defined in the deciduous dentition, south australian children of european descent appeared to show a gradient of decreasing size variability from anterior to posterior, with the second deciduous molar being particularly stable. gradients in variation of deciduous tooth measures of recent children from spitalfields cemetery, london show the greatest variability in anterior teeth and stability in second molar teeth (liversidge and molleson, 1999), in accord with the mgf concept. that the second deciduous molar is the key (most stable) tooth in the molar field is supported by stability in size variation and asymmetry of dm2 in the spitalfields sample and by expression of the protostylid noted by dahlberg (1950). the differential patterning of coefficients of variation (cv) in deciduous teeth of male japanese singletons and twins is almost the same as in the permanent dentition, suggesting the existence of three mgfs in the deciduous dentition (mizoguchi, 1998). though exceptions exist, this assessment is based on the presumption that the pattern of cvs reflects the extent of mgf control of crown size. the validity of dahlberg’s field hypothesis for the deciduous dentition requires further research into local environmental factors and concrete variables including inducing substances and homeobox genes (mizoguchi, 1998). while reports of deciduous tooth crown size (dtcs) allege that observed variation is consistent with mgf theory, these reports are few in number, population-specific, and include exceptions. a wider review of data is essential to determine the degree to which the field concept applies broadly and consistently to dtcs in ethnically and geographically diverse populations. materials this analysis emanates from original research on deciduous dental attributes in prehistoric and living samples from india and indonesia. these studies included variability in crown dimensions (lukacs 1981, 2016, 2019, 2022; lukacs et al., 1983; lukacs and kuswandari, 2022), non-metric dental morphology (lukacs and walimbe, 1984; lukacs and kuswandari, 2009, 2013), developmental enamel defects (lukacs, 1991; lukacs and walimbe, 1998; lukacs et al., 2001a, 2001b), and diachronic change in deciduous dental traits (lukacs and walimbe, 2005; lukacs, 2007). collectively this research gives deeper insight into biological relationships and health in otherwise understudied regions of the world. the recent re-analysis of indonesian dtcs and inter-group variation in sex dimorphism in the deciduous dentition led to this study (lukacs and kuswandari, 2022). this study is designed to determine if patterns of deciduous dental variation within and between populations are consistent with mgfs in a manner analogous to developmental fields in the permanent dentition. a search of the scientific literature (anthrosource, medline, web of science) revealed the rapidly increasing growth of reports on dtcs among widespread populations. the thirty-five samples in this study have a global distribution, are ethnically diverse, and geographically widespread (table 1). criteria for selecting studies to include in this analysis focused on the presence of: descriptive odontometric statistics including cv or data from which cv could be computed (mean, standard deviation), a protocol ensuring reliability of tooth crown measurement methodology (repeat measures, evaluation of measurement error), and broad geographic and ethnic distribution of study https://www.qmul.ac.uk/dentistry/atlas/ 15 dental anthropology 2023 │ volume 36│ issue 01 samples. studies that did not present data by sex and/or were based on small samples were excluded, such as moss and chase’s (1966) analysis of liberian children (n= 21), for example. indigenous and modern samples from all continents are included. four indigenous groups include the bunun (taiwan); pima (native north america), san, kalahari (south africa), and warlpiri yuendumu (central australia). though global in origin, samples are unevenly distributed with a bias toward east asia (china, japan; n=8) and europe (n=6), and underrepresentation of other groups (middle east, south america). a shortcoming not evident from this list is that crown dimensions are not reported for all teeth in all groups (see table 1). for example, incisor dimensions were not included in adler and donlon’s (2010) analysis of australians of european descent, and only measurements for deciduous molars were reported for the indian (puducherry; sujitha et al., 2021) and spanish (madrid; barberia et al., 2009) samples. buccolingual dimensions of incisor and canine teeth were not part of kaul and prakash’s (1984) description of jat odontometrics. yet more commonly, bl dimensions are not reported at all or especially for anterior teeth, thus precluding computation of table 1. global distribution and data source of samples included in study (n = 35) region location group data data source africa (n=4) afroamerican tennessee all vaughn & harris, 1992 sub-saharan kalahari san all grine, 2009 sub-saharan south afr black all grine, 1986 sub-saharan nigerian all egibobo et al., 2010 american (n=5) euroamerican burlington white all devito, 1988 euroamerican michigan white all black, 1978 native pima all alvrus, 2000 dominican mulatto all garcia-godoy et al., 1985 south colombian md botero et al., 2015 asia – east (n=9) chinese taiwan 1 all tsai, 2000 chinese taiwan 2 all liu et al., 2000 indigenous taiwan 3 md lee, 1978 japan japan 1970 md makiguchi et al., 2018 japan japan 2000 md makiguchi et al., 2018 japan various md ooshima et al., 1996 japan nagoya all yamada et al., 1986a, b japan tokyo all tsutsumi et al., 1993 korea south all baik et al., 2002 asia south (n=4) india puducherry inc sujitha et al., 2021 india gujarat all lukacs et al., 1983 india jat inc kaul & prakash, 1984 india wardha all chaudhury et al., 2011 asia southeast (n=2) indonesia malay all lukacs & kuswandari, 2022 vietnam native all huynh et al., 2020 australia (n=4) indigenous warlpiri-yuendumu all margetts & brown, 1978 european southern white all farmer & townsend, 1993 melanseia nasioi all bailit et al., 1968 sydney white inc adler & donlon, 2010 europe (n=6) iceland modern all alexsson & kirveskari, 1984 london spitalfields all liversidge & molleson, 1999 poland medieval all zadzinska et al., 2008 portugal nmnh, lisbon all cardoso, 2010 spain granada all viciano et al., 2013 spain madrid inc barberia et al., 2009 middle east (n=1) jordan irbid all hattab et al., 1999 16 dental anthropology 2023 │ volume 36│ issue 01 compound variables like crown area (md x bl). mesiodistal dimensions are clinically relevant to issues of spacing and occlusion and some reports comprise only md data. examples include, colombian (medellin; botero et al., 2015), japanese (ooshima et al., 1996), javanese (kuswandari and nishino, 2004), and the indigenous bunun of taiwan (lee, 1978). hence, md crown dimensions were selected for a worldwide analysis of temporospatial variations and sex dimorphism by harris (2001, harris and lease, 2005: 594); bl measurements were less frequently and consistently reported. methods multiple methods were used to determine if dtcs and patterns of variability meet expectations of mgfs as defined in permanent teeth. two levels are used to evaluate variability in deciduous tooth dimensions: intra-population and inter-population. first, differences in linear dimensions, ratios, and crown areas of adjacent teeth were evaluated within populations. data came from individual reports of tooth crown size or were calculated from reported mean values. analysis within each population compares variability in dtcs by tooth across dimensions (md, bl) and arcades (maxilla, mandible). second, inter-population assessment of coefficients of variation for linear dimensions (md & bl, mm) and crown areas (ca = md x bl, mm2) were calculated and assessed. the summary data: mean md and bl (linear), cv (index) and, and ca (area) from all studies were evaluated for normality using the shapiro-wilk (1965) test before computing means across all groups. the cv is a relative measure of variability that indicates the size of a standard deviation in relation to the mean. a standardized, dimensionless measure, a cv allows you to compare variability between disparate groups and traits. the cv is occasionally referred to as the relative standard deviation. cvs are often used to analyze mammalian odontometric variation as reviewed by polly (1998). the cvs were taken directly from published reports on deciduous tooth crown dimensions. since two positively correlated linear dimensions contribute to overall crown size, crown area (ca) was computed from reported data for each tooth (ca = mean md * mean bl; in mm2) and the cvs of mean cas across populations were examined. if cvs were not given in a study, they were calculated from mean values and standard deviations for each linear dimension (md and bl) of each maxillary and mandibular tooth. if standard deviation was not included among descriptive statistics in a report it was calculated from the standard error (cv = std error * √n), then the cv was determined. to be clear, mean cvs of linear dimensions (md, bl) were computed across populations and have an associated standard deviation. however, since cas are a product of mean md and mean bl of each dental element in each population there’s no way to obtain a mean cv (and standard deviation) for each ca across all populations. hence the cvs of the mean ca values were assessed for relative variability using forkman’s (2009) f test. differences in mean cv across populations were evaluated by first applying a test for normality (shapiro-wilk), to each variable and if normal, an f-test for equality of variances was conducted before the t-test was run (α = 0.05). if data failed the normality test a mann-whitney ranksum test for differences in median values was used with 25% and 75% confidence values. tooth crown size databases were created and stored in excel (microsoft office 365 proplus), statistical analysis was conducted in excel data analysis and in saspc (ver. 9.3), graphics were prepared using sigmaplot for windows (ver. 11.0). statistical significance of differences in cv were evaluated using forkman’s (2009) approximate f test for equality of cvs in medcalc (v.20.144; belgium; www.medcalc.org). the cvs for a set of measurements within a population, say md dimension of maxillary teeth, were ranked from one to five in order of decreasing cv from most to least variable tooth. the tooth with the largest cv was ranked one (most variable), the tooth with the lowest variability was ranked five, the least variable, or the most stable tooth in the set. this procedure was followed independently by jaw and dimension for each tooth in each population resulting in four sets of rankings for each data set (md-maxilla, md-mandible; bl-maxilla, blmandible). the relative frequency of ranks across all groups was determined for each tooth and dimension to identify patterns of variability, based on cvs, throughout the dental arcade. which teeth exhibit greater variability? which teeth are most stable? can patterns of variability be identified and do they follow expectations of mgfs in permanent teeth? if mgfs, as described for permanent teeth, are expressed in the deciduous dentition, observed patterns of deciduous crown size and variability should reveal a series of specific expectations (table 2). these are described below. morphogenetic fields in deciduous incisor teeth the concept of dental morphogenetic fields when http://www.medcalc.org 17 dental anthropology 2023 │ volume 36│ issue 01 applied to the pattern of metric variation in permanent incisors has several components and is different for upper and lower incisor teeth (dahlberg, 1945, 1951). initially, the description of mgfs applied to human permanent teeth focused on morphometric attributes of native americans in a comparative perspective. in upper incisors: the central incisor is the key or polar tooth and is larger and more stable (less variable) than the lateral incisor. by contrast, lower permanent incisors exhibit a reversed morphogenetic field, opposite that expressed in upper incisors. in md size the ldi1 is smaller and less stable (more variable) than ldi2, which is the polar tooth and is larger and less variable. after assessing variability in incisor crown size, patterning of coefficients of variation is evaluated across the deciduous dental arcade. results a brief description of the data used in this analysis precedes presentation of results. sample sizes varied across dental elements and studies, but mean sample sizes (n) varied from 80 to 106 for md (34 studies) and from 50 to 75 for bl dimensions (29 studies). sample sizes for mean crown dimensions, mean cvs, and mean cas analyzed in this analysis represent means across studied groups (e.g. interpopulation) from which data were derived. shapiro-wilk tests of normality revealed the majority of variables match a pattern expected if drawn from a population with a normal distribution; 90% of sample means (8/10 md, 9/10 bl, 10/10 ca) passed, and 80% of coefficients of variation passed (6/10 md_cv, 9/10 bl_cv, and 10/10 ca_cv) with α = 0.05. thus, skewness and kurtosis are unlikely to impact this analysis of deciduous dental variability. results are presented in two sections. the first focuses on patterning of variability in incisor teeth. the second addresses the results of three different approaches to patterns of variability in deciduous tooth crown metrics. is the pattern of metric variation observed in the deciduous dentition concordant with expectations based on mgfs in permanent incisors? analysis of results focused initially on incisor teeth because reversed fields have been described for upper and lower permanent incisors. in relative md and bl size, the observed pattern is that udi1 exhibits attributes of a polar or key tooth. table 3 shows that in size the udi1 is larger and less variable, has a lower sd and cvs than udi2 in both dimensions. by contrast, mandibular incisors reveal a mixed pattern, not fully consistent with field theory expectations. the lateral incisor is significantly larger in md and bl dimensions than the central incisor as expected (p<0.0001), and consistent with expectation, ldi2 is less variable than ldi1 in bl dimension. yet in md diameter the lower lateral incisor is more variable than ldi1, an observation inconsistent with mgf patterning in permanent lower incisors. the pattern of odontometric variation in size and variability of deciduous upper incisors follows expectations based on the description of morphogenetic fields in permanent maxillary incisor teeth. in mandibular incisors the size differential is consistent with field expectations lateral incisors are significantly greater in md and bl dimension than centrals, however, ldi2 is less variable than ldi1. however, cv is greater for the md dimension of ldi2 than ldi1, an unexpected result not compatible with reduced variation expected of a polar or key tooth. table 2. crown size and variability expectations for deciduous tooth types based upon the mgf theory as described for permanent dentition (butler, 1939; dahlberg, 1945, 1951) arcade expectations: deciduous teeth basis for expectations: permanent teeth size variability maxilla di1 > di2 di1 < di2 i1 is a polar tooth, larger and less variable than i2 dm1 > c > di2 dm1 < c < di2 based on tooth position and development dm1 < dm2 dm1 > dm2 m1 developmentally more stable than m2 or m3 dm2 and m1 are developmentally closely related with both arising from the same dental lamina with developmental timing that overlaps but with dm2 initiation preceding m1 mandible di1 < di2 di1 > di2 i1 is smaller and more variable than i2 dm1 > c < di2 dm1 < c < di2 based on tooth position and development dm1 < dm2 dm1 > dm2 same reasons as for maxilla 18 dental anthropology 2023 │ volume 36│ issue 01 variability in deciduous teeth across the arcade: metric and rank analyses to determine if patterns of deciduous odontometric variability follow expectations predicted by patterns documented by mgfs in permanent teeth (see table 2), three analyses were conducted. the first examines the expression mean cvs by tooth and dimension across the arcade and across populations. the second investigates relative size of mean cas and their associated cvs. the third quantifies the rank order of cvs from di1 to dm2 by jaw and dimension across populations. descriptive statistics for mean cvs for males are presented in table 3. mean crown dimensions (n, mean, sd, min, max) and mean coefficients of variation (x ̅ cv, sd) across populations are provided. figure 1 provides a graphic representation of data that allows easy visualization of differences in cv by tooth and dimension. results for females exhibit the same pattern as males and are not presented. the overall result follows expectations in that dental elements exhibit a gradation of decreasing variability (or increased stability) from anterior to posterior elements of the dentition (from di2 to dm2). more specifically: a) the upper central incisor (udi1) is less variable, than the upper lateral incisor (udi2) in md and bl dimensions, b) all second molars (dm2) have lower mean cvs than first molar teeth in upper and lower arcades, and c) the lower lateral incisor (di2) is more stable (lower cv) than the central incisor (di1) in bl dimension. the relative amount of variability in anterior (incisors) and posterior (molars) teeth were tested with an assessment of significant differences in mean cv. the largest x ̅ cvs in a dental quadrant (bold values) are consistently found in incisor teeth and the smallest x ̅ cvs (bold values) occur in dm2s. in three of four comparisons (see table 3) the difference between largest and smallest x ̅ cvs were found to be significant using forkman’s (2009) f-test: ldi2_md vs. ldm2_md (f=0.3919, p=0.0098); udi2_bl vs. udm2_bl (f=0.3825, p=0.0158), and ldi1_bl vs. ldm2_bl (f=0.4303, p=0.0336). however, this difference is non-significant in one quadrant (udi2_md vs. udm2_md; f=0.6354, p=0.2060). these observations are all consistent with expectations of mgf as described for permanent teeth. the only exception is in the md dimension of the lateral incisor (di2) which has a greater mean cv than the central incisor (di1). these results show that for maxillary and mandibular molars, dm2s consistently exhibit lower x ̅ cvs than dm1s. most comparisons of mean cvs are consistent with mgf expectations with one exception. table 3. mean crown dimensions (n, mean, sd, min, max) and mean coefficient of variation (x ̅ cv, sd) across populations (males only; see fig. 1) mesiodistal variable n mean sd x ̅ cv sd min max udi1 3 1 6.59 0.28 6.32 1.14 5.80 7.35 udi2 3 1 5.38 0.25 6.78 1.22 4.91 6.00 udc 3 2 6.83 0.20 5.93 0.93 6.48 7.41 udm1 3 4 7.40 0.29 6.16 1.28 6.69 8.25 udm2 3 4 9.22 0.41 5.40 1.27 8.58 10.55 f=0.6354; p=0.2060 ldi1 3 1 4.21 0.22 7.50 1.42 3.86 4.97 ldi2 3 1 4.69 0.17 7.89 1.80 4.25 5.01 ldc 3 2 5.94 0.18 6.26 1.69 5.68 6.48 ldm1 3 4 8.12 0.25 5.62 1.24 7.43 8.54 ldm2 3 4 10.16 0.35 4.93 1.45 9.39 10.89 f=0.3919; p=0.0098 buccolingual udi1 2 5 5.04 0.21 7.07 1.60 4.48 5.47 udi2 2 5 4.76 0.25 8.10 1.76 3.87 5.24 udc 2 6 6.03 0.28 7.61 1.64 5.39 6.61 udm1 2 9 8.65 0.34 5.52 1.62 7.73 9.17 udm2 2 9 9.95 0.3 5.00 1.20 9.44 10.65 f=0.3825; p=0.0158 ldi1 2 5 3.83 0.18 7.91 1.86 3.53 4.33 ldi2 2 5 4.28 0.19 7.35 1.62 3.95 4.75 ldc 2 6 5.52 0.21 7.08 1.39 5.13 6.05 ldm1 2 9 7.33 0.42 6.41 1.73 6.17 7.98 ldm2 2 9 9.09 0.37 5.18 1.65 8.54 10.02 f=0.4303; p=0.0336 n = sample size; sd = standard deviation; cv = cv for mean for all samples; min = minimum; max = maximum; bold = largest and smallest cv by dimension and arcade; f=test for equal cvs, p-value, α=0.05 19 dental anthropology 2023 │ volume 36│ issue 01 figure 1. mean coefficients of variation (cv) for mean tooth crown size (maxillary upper panel, mandibular lower panel, mesiodistal md and buccolingual bl; see table 3). 20 dental anthropology 2023 │ volume 36│ issue 01 the second approach focuses on variability in cas across the dental elements. covariation of md and bl dimensions varies among elements of the dental arcade, hence ca (mm2) provides an approximate overall estimate of tooth size. for this reason, cvs for each mean ca were calculated and plotted. the results include mean cas, associated cvs, and descriptive statistics (table 4, figure 2). are key teeth less variable? do they have lower cvs than non-key dental elements? in four comparisons of adjacent teeth, (upper and lower incisors; upper and lower molars) prospective key teeth have lower cvs than non-key teeth, thus exhibiting patterns of variation consistent with field theory expectations. the cv comparisons consistent with field theory include: udi2 > udi1, ldi1 > ldi2, udm1 > udm2, and ldm1 > ldm2. an f test for significant differences between largest and smallest cvs (forkman, 2009) shows that incisors (udi2, ldi1) are more variable than second molars (udm2, ldm2) (see table 4). the cv for crown area of the udc is intermediate between values for upper incisors and upper molars, while the cv for ldc falls between the lower incisors and dm2. the third analysis examines the rank of relative variability in cv for each tooth by dimension and by jaw across populations. results are presented graphically for md (figure 3) and bl (figure 4) dimensions. data are presented in summary form in table 5 and raw data by population in table 6. note that not all ranks were observed for all teeth. the bl dimension of maxillary teeth and second molar teeth exhibit fewer than five ranks; ranks not observed are omitted from figures. for example, in the upper bl dimension (see figure 4, top panel) three ranks (1, 2, 3) were observed and plotted for udi2, and only two ranks (4, 5) were present and graphed for the bl dimension of udm2. ranks not observed are omitted from the figure and not plotted are indicated by a double dash (--). close examination of figures 3 and 4 reveals several patterns: a) ranks one through three have a high frequency in both dimensions (md, bl) in central and lateral incisors, upper and lower, b) rank five (least variable) has the highest frequency in second molars and is evident in both jaws and both dimensions, c) the first molar is more variable than the second molar with a greater number of ranks observed and with rank 4 attaining highest frequencies, and d) canines display a pattern of ranked variation intermediate between incisor and molar teeth. rankings of coefficients of variation (cv) by ditable 4. mean crown areas (x ̅ ca) and coefficients of variation (cv) across populations (males only; see fig. 2) tooth n x ̅ ca cv sd min max maxilla di1 25 33.28 8.16 2.71 26.92 40.20 di2 25 25.70 9.07 2.33 19.00 31.44 dc 25 41.22 7.20 2.97 36.77 48.98 dm1 25 64.26 5.33 3.42 58.03 70.30 dm2 22 89.55 5.15 4.62 81.00 97.29 f=3.0852 p=0.0113 mandible di1 25 16.21 8.86 1.44 14.01 19.53 di2 25 20.13 7.30 1.47 17.48 23.80 dc 25 32.88 6.48 2.13 29.55 38.18 dm1 25 59.89 6.56 3.93 50.90 67.11 dm2 22 91.02 5.46 4.97 81.51 99.99 f=2.6209 p=0.0291 figure 2. coefficients of variation for mean tooth crown areas (cas; see table 4). 21 dental anthropology 2023 │ volume 36│ issue 01 figure 3. histogram of cvs in rank order from most (rank 1) to least (rank 5) variable: mesiodistal dimension (maxillary upper panel; mandibular lower panel; see table 5). figure 4. histogram of cvs in rank order from most (rank 1) to least (rank 5) variable: buccolingual dimension (maxillary upper panel; mandibular lower panel; see table 5). table 5. frequency (f, %) by rank order of cvs for md and bl dimensions across populations (raw data by population, table 6) di1 di2 udc udm1 udm2 rank f % f % f % f % f % mesiodistal maxillary 1 5 17.24 12 41.38 5 17.24 4 13.79 3 10.34 2 8 27.59 9 31.03 4 13.79 5 17.24 3 10.34 3 8 27.59 3 10.34 5 17.24 13 44.83 -- 4 5 17.24 4 13.79 8 27.59 5 17.24 7 24.14 5 3 10.34 1 3.45 7 24.14 2 6.90 16 55.17 mandibular 1 14 48.28 13 44.83 1 3.45 1 3.45 -- 2 7 24.14 12 41.38 7 24.14 3 10.34 -- 3 5 17.24 3 10.34 10 34.48 10 34.48 2 6.90 4 3 10.34 --8 27.59 12 41.38 5 17.24 5 --1 3.45 3 10.34 3 10.34 22 75.86 buccolingual maxillary 1 6 25.00 9 37.50 9 37.50 ---- 2 8 33.33 12 50.00 4 16.67 ---- 3 9 37.50 3 12.50 8 33.33 4 16.67 -- 4 1 4.17 --3 12.50 15 62.5 5 20.83 5 ------5 20.83 19 79.17 mandibular 1 12 50.00 6 25.00 3 12.50 3 12.50 -- 2 6 25.00 9 37.50 6 25.00 2 8.33 1 4.17 3 4 16.67 5 20.83 11 45.83 4 16.67 -- 4 1 4.17 3 12.50 4 16.67 13 54.17 3 12.50 5 1 4.17 1 4.17 --2 8.33 20 83.33 22 dental anthropology 2023 │ volume 36│ issue 01 t ab le 6 . r an k or d er o f to ot h v ar ia b il it y ( c oe ff ic ie n t of v ar ia ti on ) b y t oo th , ja w a n d d im en si on ( 1 = la rg es t c v , 5 = sm al le st c v ; m al es o n ly ). ja w m a x il la m a n d ib le d im e n si o n m e si o d is ta l b u cc o li n g u a l m e si o d is ta l b u cc o li n g u a l so u rc e \ t o o th d i1 d i2 d c d m 1 d m 2 d i1 d i2 d c d m 1 d m 2 d i1 d i2 d c d m 1 d m 2 d i1 d i2 d c d m 1 d m 2 a fr ic a _ s , b la ck 1 2 3 4 5 2 1 4 3 5 4 1 2 3 5 2 1 4 3 5 a fr ic a , k a la h a ri 2 1 4 3 5 1 2 3 4 5 3 1 2 4 5 1 2 3 4 5 a m b la ck , t n 3 5 4 2 1 1 2 4 3 5 2 1 3 4 5 1 5 4 3 2 a m w h it e , b u rl 2 1 4 3 5 3 2 1 4 5 1 2 4 3 5 2 3 1 4 5 a m w h it e , m i 3 1 4 2 5 2 1 3 4 5 1 2 3 4 5 1 2 4 3 5 a u st ra li a , w a rl p ir i 3 1 5 2 4 1 2 3 4 5 2 1 4 3 5 3 1 2 4 5 a u st ra li a , w h it e 2 1 3 4 5 2 1 3 4 5 1 2 4 3 5 2 1 3 4 5 d o m in ic a n 2 3 1 4 5 3 2 1 4 5 3 1 2 4 5 1 2 3 5 4 ic e la n d 2 1 4 3 5 3 1 2 4 5 2 1 3 4 5 3 1 2 4 5 ja p a n _ 1 9 7 0 5 1 4 3 2 - - - - - 1 2 4 3 5 - - - - - ja p a n _ 2 0 0 0 5 4 2 3 1 - - - - - 1 2 4 3 5 - - - - - ja p a n , n a g o y a 3 1 5 2 4 2 1 4 3 5 1 2 5 3 4 3 2 1 5 4 ja p a n _ o o sh im a 1 2 4 3 5 - - - - - 1 2 3 4 5 - - - - - ja v a , m a la y 4 2 1 3 5 3 2 1 4 5 1 2 4 3 5 1 2 3 4 5 in d ia , g u ja ra t 4 1 5 3 2 4 2 1 3 5 1 2 4 5 3 5 3 2 1 4 in d ia , ja t 1 2 4 3 5 - - - - - 1 2 3 4 5 - - - - - in d ia , w a rd h a 2 3 1 4 5 1 2 3 4 5 1 3 2 4 5 1 2 3 4 5 jo rd a n 4 1 2 3 5 2 1 3 4 5 2 1 3 4 5 1 3 2 4 5 k o re a , s o u th 4 3 1 2 5 3 2 1 4 5 2 1 5 3 4 1 2 3 4 5 l o n d o n , s p it a l 1 2 3 5 4 3 2 1 5 4 1 5 3 2 3 2 4 3 1 5 p im a , n n a 3 2 5 1 4 2 3 1 5 4 1 2 3 4 5 1 4 2 3 5 m e la n e si a -n a si o i 3 4 5 1 2 3 1 2 5 4 2 1 3 4 5 2 1 3 4 5 n ig e ri a 4 2 5 3 1 1 2 3 5 4 3 1 2 4 5 2 1 3 4 5 p o la n d 2 4 3 1 5 2 3 1 4 5 4 3 1 2 5 4 3 2 1 5 s p a in , g ra n a d a 2 1 3 5 4 3 1 2 5 4 3 1 2 5 4 3 2 1 4 5 t a iw a n 1 3 2 1 4 5 3 1 2 4 5 1 2 4 3 5 1 4 3 2 5 t a iw a n 2 1 2 5 3 4 1 2 3 4 5 3 1 2 5 4 1 2 3 4 5 t a iw a n 3 5 1 2 3 4 - - - - - 2 3 5 1 4 - - - - - v ie tn a m 3 4 2 1 5 2 3 1 4 5 4 1 3 2 5 1 3 4 2 5 23 dental anthropology 2023 │ volume 36│ issue 01 mension (md and bl) and by jaw exhibit patterns consistent with the hypothesis that deciduous dental variation is mediated by mgf-like mechanisms during development. discussion the conclusion to kieser’s (1990: 88) chapter on odontometric variability states that, “dental dimensional variability emerges as a complex phenomenon and will probably require a complex synthesis of ideas for its explanation.” the multitude and diversity of hypotheses make some models unfalsifiable using variability statistics (from butler and dahlberg’s fields, waddington’s epigenetic canalization, osborn’s clones, pengilly’s functional relations, and grigerich’s occlusal complexity). these observations relate to the more thoroughly documented variability observed in the permanent dentition, “the honest answer at the moment is that we do not know the exact cause for the observed patterning of odontometric variability in man” (kieser, 1990: 88). this investigation of odontometric variability in deciduous teeth yields insight into important yet unresolved issues. the data presented here for patterns of variability in deciduous tooth crown dimensions are mainly in agreement with predictions based on morphogenetic fields as described for permanent teeth. the pattern of variability in deciduous dentition differs in several ways from that described for permanent teeth: a) three fields not four -are sufficient to explain patterns observed, b) incisor variability follows expectation, with one exception, c) second molars are larger and more stable than first molars, and d) a canine field is implied by variability intermediate between incisor and molar teeth. though the findings documented in this report have merit they do not allow confirmation of one or another cause for the observed patterning of variability. we can see that deciduous tooth crown variability adheres to patterns of variation predicted by mgfs to explain variability in permanent teeth. the number of samples and their global and ethnic diversity gives these results a broad empirical base, yet several questions remain. the lower lateral incisor md is more variable than the central, a deviation from expectation. does this result suggest that lower incisors do not fully adhere to the reversed mgf of lower incisors in permanent teeth? additional unanswered questions center on patterns of variability across the transition from deciduous to permanent teeth. is the deciduous second molar more, or less, stable than the first permanent molar? which is the key or polar tooth in the molar mgf? how does variability in deciduous molars compare with that of their succedent permanent premolar teeth? a final question regards causality. mizoguchi (1998), farmer and townsend (1993), kieser (1990), and others point to the timing of dental development as a potential explanation for the observed patterning of variability. several studies propose that the time a tooth spends in the pre-calcification, or soft tissue stage of development is a potential explanation. deciduous incisors are longer in precalcification and more variable in crown dimensions, while molars have less time in the soft tissues stage and are more stable odontometrically. differences in form and development between dm1, dm2 and m1 are notable. deciduous teeth and the permanent first molar are derived from the same primary dental lamina (bailey, 2014, 2017), and butler (1956, 1967) noted these differences are to some extent adaptive. “dm2 has a much shorter period of function than m1, and it operates in a smaller mouth and shorter jaw. it is a deciduous tooth, whereas m1 is a permanent tooth. from a morphogenetic point of view, however, the two teeth belong to the same series, and their differences may be ascribed to position within the series” (butler, 1967: 1259). thus, “…it is tempting to see the deciduous second molar and permanent first molar as representing different stages of the same ontogenetic process” (bailey et al., 2014: 112). in this analysis dm2 is odontometrically the least variable tooth in the deciduous dentition and its development is closely linked to m1 suggesting that dm2 is the polar or key tooth of the meristic molar series (dm2 thru m3) (smith et al., 1987, 1997). conclusions patterns of odontometric variability in deciduous tooth crown size are largely consistent with expectations described for permanent teeth. this correspondence is evident in results from three different analyses and is based on a large and diverse sample of populations. independent studies of metric variation in deciduous tooth crown measurements have interpreted results consistent with the dental morphogenetic field concept. these studies now have further validation and confirmation from the results reported here. further analysis of deciduous tooth crown variability in relation to morphogenetic field theory is in progress using statistical procedures for meta-analysis and multivariate methods (e.g., principal components analysis). 24 dental anthropology 2023 │ volume 36│ issue 01 acknowledgments initial studies of morphometric variation in deciduous teeth of prehistoric and living groups in india and indonesia were funded by the american institute of indian studies, national geographic society national science foundation, the smithsonian institution foreign currency program, and the wenner-gren foundation. special thanks to colleagues and institutions for collaboration in research: allahabad university, allahabad (jn pal, vd misra), deccan college, pune (gl badam, sr walimbe), gadjah mada university, yogyakarta (sri kuswandari), and government dental college & hospital, ahmedabad (mr joshi, pg makhija). special thanks to bruce floyd (university of auckland) for critical evaluation of the first draft of this manuscript and suggestions for improvement. references adler, c. j., & donlon, d. 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(2008). sex diagnosis of subadult specimens from medieval polish archaeological sites: metric analysis of deciduous dentition. homo -journal of comparative human biology, 59(3), 175-187. dean and knoppe 2008.4 21 daris r. swindler, professor emeritus of anthropology at the university of washington, seattle, passed away on december 6, 2007, after a brief acute illness in spokane. he was 82 years old. much of his scientific work was related to dental anthropology and craniofacial growth and development. a longtime member of the dental anthropology association, swindler served as its president from 1990 to 1992. from 1996 to 2001 he belonged to the editorial board of dental anthropology. with his death dental anthropology has lost one of its finest scholars and supporters. the 14th international symposium on dental morphology in greifswald, germany in august 2008 will commemorate his life and will honor his most valuable contribution to dental anthropology. daris r. swindler was born in morgantown, west virginia in 1925. since his junior years in highschool, swindler had been interested in the evolution and the diversity of recent humankind. this interest was greatly fostered by the reading of “on the trail of ancient man” by roy chapman andrews. interrupted by his volunteer service for the us navy during the second world war, swindler began his higher education at the university of west virginia. as a graduate student at the university of pennsylvania he studied with drs. wilton h. krogman, loren eisely and carleton coon. especially influential was his acquaintance with krogman that inspired his continuing interest in craniofacial growth and development, and especially of teeth. in 1954 he participated in an expedition to new britain with ward goodenough, ann chowning and charles a. valentine. this had a great impact on daris swindler’s future work. not only was his doctoral dissertation in anthropology, which he completed in 1959, largely based on the material that he collected during these five months, but the time he spent with the lakalai people assured him of his career choice as a physical anthropologist. in his most recent book “new britain diary, 1954: an anthropologist’s journal”, daris r. swindler reflects his encounter with the lakalai [p. 34] “as i walked back along the beach that evening, all that had happened today was swimming about in my head: thoughts about our earth and its many people, its many religions and cultures, and then i realized: this is why i became an anthropologist.” though he was never able to return to new britain, his interest in the various cultural regions of the pacific continued. in 1996 he joined an italian expedition to easter island as a field consultant in dental anthropology and one year later accepted an invitation to lecture on micronesian anthropology on the oceanic grace cruise line through micronesia. from 1954 to1968 swindler taught human anatomy at several academic institutions including the university of pennsylvania graduate school of medicine, cornell university medical school, west virginia university medical school, the medical college of south carolina, and michigan state university. in 1968 swindler was appointed full professor at the department of anthropology, university of washington. over this same time period he was also an adjunct curator of primate anatomy, burke memorial washington state museum. after his retirement in 1991 he was invited to be visiting professor by the university of zurich, switzerland (1992), the university of padua, italy (1994), and by the okayama university school of dentistry, japan (1998). swindler’s research interests included primate anatomy, early primate dental development, comparative dental morphology and odontometrics of living and fossil primates, as well as pacific dental anthropology. several field expeditions took him to important sites such as the big horn basin, wyoming fig. 1. daris r. swindler studying primate dentitions in inuyama, japan, in 1998. obituary: daris r. swindler (1925-2007) 22 (1984-1990), pakistan (1989), as well as to the valley of the kings, egypt (1991). in recent years he carried out forensic work in cyprus for physicians for human rights. his time in seattle was very productive. several research grants from the national institutes of health (nih) allowed swindler to conduct unique longitudinal studies on craniofacial growth and development of two primate species, the pigtailed macaque (macaca nemestrina) and the yellow baboon (papio cynocephalus). huge datasets accrued from x-ray-films, dental casts, body and head measurements, which were studied extensively by swindler and his graduate students, most notably dr. joyce sirianni. in addition to swindler’s classic work in 1973, “an atlas of comparative primate gross anatomy, baboon, chimpanzee, and man” (reprinted by robert e. krieger in 1982), with medical illustrator charles d. wood, swindler and sirianni published a substantial body of data in 1985 as an impressive book, “longitudinal growth and development of the pigtailed macaque (macaca nemestrina)” crc press, boca raton, florida. daris swindler never refused scholars access to his original data. on the contrary, he often went out of his way to promote new research that made continuing use of his own data base. in 2007, shortly before his death, daris decided to donate his enormous collection of dental casts, x-ray films, skeletons, etc. to the new york university. at the same time new york university formally established the “daris r. swindler collection” of dental primate material available for study at their center for the study of human origins (http://www. nyu.edu/gsas/dept/anthro/programs/csho/center. html). this gave daris a great sense of pride and the assurity of a productive future for his collections. swindler received many honors in his life, notably the alexander von humboldt senior scientist award from germany; the washington governor’s writer’s day award for his “an atlas of primate gross anatomy: baboon, chimpanzee and man”; the senior award for the visiting scholar exchange from the peoples republic of china; vice president of the american association of physical anthropologists; president of the dental anthropology association. he was a member of the editorial boards of several journals including journal of dental research and the yearbook of physical anthropology. he was elected a fellow of the american association for the advancement of science in 1961 and in 1992 became a fellow of the explorer’s club. swindler was a gifted writer, who published constantly over more than 50 years. his first publication was in 1955 on the absence of sickle cell anemia in melanesia. “a review of dental morphological traits in oceania” was a chapter in a festschrift (2005) for ann chowning. apart from those already mentioned, other outstanding publications include his widely acclaimed books, “the dentition of living primates” academic press, london, 1976; “introduction to primates” the university of washington press, seattle and london, 1998; “primate dentition: an introduction to the teeth of nonhuman primates” cambridge university press london, 2002. daris himself said he especially enjoyed his work as the major editor of “systematics, evolution and anatomy”, vol. 1 of comparative primate biology, alan r. liss publishing company, 1986 (with j. erwin as series editor). apart from his outstanding contribution to dental fig. 2. daris r. swindler researching in inuyama, japan, 1998. fig. 3. daris r. swindler (left) and c. loring brace, both past-presidents of the dental anthropology association. picture taken at the aapa meeting, 1996 (courtesy of e. f. harris). 2� and established academics, but also for many young researchers who were still at the start of their careers. many felt, and still feel, part of daris and kathy’s extended scientific family and many, through their friendship and support, were inspired to keep going. daris had an overwhelming trust in the future and his friends felt his love for his academic family. apart from science he loved fishing in the puget sound and was almost fanatical about american football. daris r. swindler is survived by his wife kathryn rantala swindler of spokane, seven children and seven grandchildren. everyone who knew him will agree that daris was a wonderful person. he will deeply be missed by all those to have shared so much with him and have learned so much from him though he will remain a part of dental anthropology for a very long time to come. christopher dean university college london united kingdom and thomas koppe ernst moritz arndt university greifswald germany fig. 4. daris r. swindler in switzerland. morphology and primate anatomy, swindler was known for his passion for teaching. his courses on comparative primate anatomy were particularly popular with his students. shortly before his death, daris was honored by the establishment of the daris r. swindler fellowship in biocultural anthropology in the department of anthropology of the university of washington. this fellowship marks a lasting contribution to anthropology in his name and will provide a great opportunity for many future students at the university of washington. as a truly biological anthropologist, daris r. swindler enjoyed life and its many facets to the fullest. he was always fascinated about all aspects of evolutionary biology, and loved to chat about his many interests, most notably about primate teeth. from all of the many meetings he attended, he especially favored the international symposia on dental morphology because of their special flavor and small size which encourages scientific discussions about so many aspects of dental morphology both in primates and other vertebrates. he was especially passionate about key historical figures, none more so than charles darwin and was never prouder than when he could extend his private library with another book on the subject. he and his wife kathy swindler were great hosts not just for well-known bibliography, daris r. swindler swindler dr. 2007. new britain diary, 1954: an anthropologist’s journal. spokane: ravenna press. koppe t, swindler dr. 2004. metric sexual dimorphism in the deciduous teeth of old world monkeys. ann anat 186:367-374. willis ms, swindler dr. 2004. molar size and shape variations among asian colobines. am j phys anthropol 125:51-60. swindler dr. 2002. primate dentition: an introduction to the teeth of non-human primates. (cambridge studies in biological and evolutionary anthropology.) cambridge: cambridge university press. swindler dr. fourth molars in the anthropoidea. dental anthropology 2002;16:26-28. swindler dr, drusini ag, cristino c, ranzato r. 1999. comparison of molar crown size of precontact easter islanders and others. in: mayhall jt, heikkinen t, editors. dental morphology 1998. oulu: oulu university press, p 63-73. koppe t, swindler dr, lee sh. 1999. a longitudinal study of the growth pattern of the maxillary sinus in the pig-tailed macaque (macaca nemestrina). folia primatol (basel) 70:301-312. 24 koppe t, rae tc, swindler dr. 1999. influence of craniofacial morphology on primate paranasal pneumatization. ann anat 181:77-80. siebert jr, williams b, collins d, winkler la, swindler dr. 1998. spontaneous cleft palate in a newborn gorilla (gorilla gorilla gorilla). cleft palate craniofac j 35:436-441. winkler la, schwartz jh, swindler dr. 1996. development of the orangutan permanent dentition: assessing patterns and variation in tooth development. am j phys anthropol 99:205-220. german rz, hertweck dw, sirianni je, swindler dr. 1994. heterochrony and sexual dimorphism in the pigtailed macaque (macaca nemestrina). am j phys anthropol 93:373-380. lestrel pe, bodt a, swindler dr. 1993. longitudinal study of cranial base shape changes in macaca nemestrina. am j phys anthropol 91:117-129. emel lm, swindler dr. 1992. underbite and the scaling of facial dimensions in colobine monkeys. folia primatol (basel) 58:177-189. swindler dr, emel lm. 1990. dental development, skeletal maturation and body weight at birth in pigtail macaques (macaca nemestrina). arch oral biol 35:289-294. kirch pv, swindler dr, turner cg 2nd. 1989. human skeletal and dental remains from lapita sites (1600500 b.c.) in the mussau islands, melanesia. am j phys anthropol 79:63-76. haglund wd, reay dt, swindler dr. 1989. canid scavenging/disarticulation sequence of human remains in the pacific northwest. j forensic sci 34:587-606. haglund wd, reay dt, swindler dr. 1988. tooth mark artifacts and survival of bones in animal scavenged human skeletons. j forensic sci 33:985-997. swindler dr, olshan af. 1988. comparative and evolutionary aspects of the permanent dentition. in: schwartz jh, editor. orang-utan biology. new york: oxford university press, p 271-282. swindler dr, ward s. 1988. evolutionary and morphological significance of the deflecting wrinkle in the lower molars of the hominoidea. am j phys anthropol 75:405-411. swindler dr, editor. 1986. systematics, evolution and anatomy. new york: alan r. liss. sirianni je, swindler dr. 1985. growth and development of the pigtailed macaque. boca raton: crc press, inc. olshan af, siegel af, swindler dr. 1982. robust and least-squares orthogonal mapping: methods for the study of cephalofacial form and growth. am j phys anthropol 59:131-137. swindler dr, olshan af, sirianni je. 1982. sex differences in permanent mandibular tooth development in macaca nemestrina. hum biol 54:45-52. sirianni je, van ness al, swindler dr. 1982. growth of the mandible in adolescent pigtailed macaques (macaca nemestrina). hum biol 54:31-44. swindler dr, olshan af. 1982. molar size sequence in old world monkeys. folia primatol (basel) 39:201212. daniel hj, schmidt rt, olshan af, swindler dr. 1982. ontogenetic changes in the bony labyrinth of macaca mulatta. folia primatol (basel) 38:122-129. swindler dr. 1979. the incidence of underbite occlusion in leaf-eating monkeys. ossa 6:261-272. swindler dr. 1978. the teeth of primates. burlington, nc: carolina biological supply company. turner cg 2nd, swindler dr. 1978. the dentition of new britain west nakanai melanesians. viii. peopling of the pacific. am j phys anthropol 49:361-371. swindler dr. 1976. dentition of living primates. new york: academic press. garn sm, swindler dr, minnis pe. 1975. the sex difference in dimensional communalities in macaca nemestrina. am j phys anthropol 43:19-22. swindler dr, sirianni je. 1975. tooth and body size correlations in macaca nemestrina. j dent res 54:695. sirianni je, swindler dr. 1975. size variability within the deciduous dentitions of male and female macaca nemestrina. j dent res 54:414. sirianni je, swindler dr, tarrant lh. 1975. somatometry of newborn macaca nemestrina. folia primatol (basel) 24:16-23. orlosky fj, swindler dr, mccoy-beck ha. 1974. metric trends of the anterior teeth in african monkeys. hum biol 46:647-661. chase ce, swindler dr. 1974. a system for automatic recording of odontometric material. j dent res 53:1506. swindler dr, wood dc. 1973. an atlas of primate gross anatomy: baboon, chimpanzee, and man. seattle: university of washington press. tarrant lh, swindler dr. 1973. prenatal dental development in the black howler monkey (alouatta caraya). am j phys anthropol 38:255-259. sirianni je, swindler dr. 1973. inheritance of deciduous tooth size in macaca nemestrina. j dent res 52:179. swindler dr, sirianni je. 1973. palatal growth rates in macaca nemestrina and papio cynocephalus. am j phys anthropol 38:83-91. swindler dr, tarrant lh. 1973. the topography of the premaxillary-frontal region in nonhuman primates. folia primatol (basel) 19:18-23. swindler dr, orlosky fj. 1972. metric and morphological variability in the dentition of colobine monkeys. j hum evol 3:135-160. tarrant lh, swindler dr. 1972. the state of the deciduous dentition of a chimpanzee fetus (pan troglodytes). j dent res 51:677. swindler dr, merrill om. 1971. spontaneous cleft lip 25 and palate in a living nonhuman primate, macaca mulatta. am j phys anthropol 34:435-439. swindler dr, sirriani je. 1969. variability of maxillary incisors among primates. viiith int congr anthrop ethnol sci, s-2 dental aspects, p 308-311. aulerich rj, swindler dr. 1968. the dentition of the mink (mustela vison). j mammal 49:488-494. swindler dr. 1968. the maxillary incisors and evolution of old world monkeys. in: chiarelli b, editor. taxonomy and phylogeny of old world primates with references to the origin of man. torino, italy: rosenberg and sellier, p 57-67. swindler dr, orlosky fj, hendrick ag. 1968. calcification of the deciduous molars in baboons (papio anubis) and other primates. j dent res 47:167170. swindler dr, mccoy ja, hornbeck pv. 1967. the dentition of the baboon (papio anubis). in: vagtborg h, editor. the baboon in medical research, vol. ii. austin: university of texas press, p 133-150. garn sm, lewis ab, swindler dr, kerewsky rs. 1967. genetic control of sexual dimorphism in tooth size. j dent res 46:963-972. hornbeck pv, swindler dr. 1967. morphology of the lower fourth premolar of certain cercopithecidae. j dent res 46:979-983. swindler dr. 1967. lawrence oschinsky: 1921-1965. am j phys anthropol 26:371-372. swindler dr, gavan ja. 1966. variability of mandibular tooth formation in the rhesus monkey. j dent res 45:1234. gavan ja, swindler dr. 1966. growth rates and phylogeny in primates. am j phys anthropol 24:181190. swindler dr, mccoy ha. 1965. primate odontogenesis. j dent res 44:suppl:283-295. swindler dr, mccoy ha. 1964. calcification of deciduous teeth in rhesus monkeys. science 144:1243-1244. swindler dr, gavan ja, turner wm. 1963. molar tooth size variability in african monkeys. hum biol 35:104122. mavawala j, swindler dr, hunt ee jr. 1963. the dermatoglyphics of the west nakanai of new britain. am j phys anthropol 21:335-340. swindler dr, gavan ja. 1962. calcification of the mandibular molars in rhesus monkeys. arch oral biol 7:727-734. swindler dr. 1961. calcification of the permanent first mandibular molar in rhesus monkeys. science 134:566. graydon jj, semple nm, simmons rt, swindler dr. 1956. a blood group genetical survey in west nakanai, new britain. am j phys anthropol 14:275286. swindler dr. 1955. the absence of the sickle cell gene in several melanesian societies and its anthropologic significance. hum biol 27:284-293. [an electronic version of this bibliography is available on request. editor] the daris swindler primate dental cast collection in august 200� daris agreed to donate his collection of primate dental casts to the center for human origins, new york university. the collection consists of more than 2,000 casts representing every primate species known (and some non-primate relatives), as well as several human populations. the daris swindler primate dental cast collection is now housed in the anthropology department of nyu. undergraduate volunteers are in the process of inventorying the collection and comparing it against daris’ catalog. inventory is expected to be complete by december of 2008. the collection has already been used for a number of undergraduate and graduate student projects. in addition, researchers who are members of the new york consortium for evolutionary primatology have begun scanning some of the ape casts for comparative study. ultimately, nyu plans to scan the entire collection in three-dimensions and make it virtually available for remote researchers via an internet database. the collections will provide the foundation for developing standards for scoring non-human primate dental morphological variation. many important studies of human and non-human primate variation as well as growth and development are in the works. nyu now anticipates working with kathy swindler to arrange the transfer of the remaining collection, which includes measurements and radiographs from an 8-year growth study of macaca nemestrina, several hundred tooth buds from several species of nonhuman primates, and additional human collections from new guinea highlands and new britian. nyu and dr. bailey, in particular, are greatly indebted to daris for this generous donation. shara bailey new york university e-mail: sbailey@nyu.edu 30 dental anthropology 2019 │ volume 32 │ issue 02 periodontal disease and “oral health” in the past: new insights from ancient sudan on a very modern problem rebecca whiting 1,2* , daniel antoine 2 , and simon hillson 1 1 university college london, uk 2 the british museum, london, uk today, periodontal disease is a major health issue worldwide, with the world health organisation (who) reporting it as the eleventh most prevalent disease in the world (global burden of disease, 2017). periodontal disease is the inflammation of the gingival (gum) tissues leading to destruction of the supporting soft and hard tissues of the teeth. it is one of the foremost causes of tooth loss and without access to dentures or dental implants edentulism can become a huge problem (petersen et al., 2005). recent investigations show that both gingivitis (the inflammation of the gums) and periodontal disease (global burden of disease, 2017) are highly prevalent. in nearly every region of the globe, the community periodontal index (cpi), aimed at monitoring periodontal health, shows that 40-60% of 35-44 year olds have small or large periodontal pockets (cpi scores 3 or 4), due to inflammation, loss of attachment of the gingivae and possible bone loss. this is accompanied by a 3560% gingivitis prevalence (cpi scores 1 and 2; [global burden of disease, 2017, p. 2189]). gingivitis is also found to be highly prevalent in adolescents between the ages of 15-19 (global burden of disease, 2017; petersen et al., 2005). periodontal disease, its distribution and effects on systemic as well as oral health, are a current and global concern (barnett, 2006; bawadi et al., 2011; geethika & chava, 2016; hajishengallis & korostoff, 2017; hujoel & lingström, 2017; p. petersen & ogawa, 2012). bioarchaeological methods can be used to explore the prevalence of this disease in past populations and, as shown here, provide new data on nile valley archaeological collections against which modern prevalence and distribution rates can be compared. this new study investigates if the kerr method (kerr, 1988), which has seldom been applied to archaeological assemblages, is an appropriate method to record periodontal status. it also assesses differences in the prevalence of periodontal diseases between the neolithic and medieval periods in the middle nile, if these results vary by sex and age and how this study compares to published data from other archaeological assemblages and modern populations. few large-scale bioarchaeological studies of periodontal disease in the nile valley have been published and this study adds to our understanding of its past prevalence in a manner that accounts for the variable preservation of archaeological collections, allowing comparisons with modern clinical data. abstract as one of today’s major oral health issues, periodontal disease affects populations worldwide. here, methods used to record its past prevalence are reviewed, indicating that clinical and bioarchaeological research offers strong support for the kerr method, recording morphological changes of the interdental septum as a means of identifying periodontal disease. using kerr’s approach, four assemblages from sudan dating from the neolithic, kerma, and medieval periods are examined to track the prevalence of the disease through time. results show a significantly lower prevalence and limited oral distribution of periodontal disease in the neolithic period. at medieval period sites, significantly higher prevalence is seen with increasing age in male individuals, which is not seen in females. with no patient history and the cumulative effects of a dynamic and episodic disease, the effects of periodontal disease on the concept of ‘oral health’ may be hard to apply in archaeological remains. at best it provides an insight into the periodontal status at death a ‘snapshot’ that reveals differences across the mouth, over time and between sexes in these middle nile valley collections, giving insight into periodontal status in this region and advancing current understanding of the history of periodontal disease. *correspondence to: rebecca whiting university of college london the british museum rwhiting@britishmuseum.org keywords: periodontal disease, kerr method, interdental septum, sudan, bioarchaeology 31 dental anthropology 2019 │ volume 32 │ issue 02 materials the nile valley offers some of the largest pre-modern cemetery collections found in africa (friedman, 2007; irish, 2010; salvatori & usai, 2008b). large skeletal assemblages from a range of time periods were recently recovered in sudan (welsby, 2003), several of which were generously donated by sudan’s national corporation for antiquities and museums and are currently curated at the british museum. these include two large medieval burial sites from the fourth cataract region of the middle nile valley (figures 1 and 2) dating to the medieval (c. ad 550 -1500 – site 3-j-23) and the late medieval (c. ad 1100-1500 – site 3-j-18) periods. preservation is excellent at both sites, including some remarkable examples of natural mummification, providing insights into the state of periodontal disease in pre-industrial northeastern africa. the older sites of h29 (kerma ancien 2050-1750 bc) and r12 (neolithic 3500 bc) were also included to explore the progression of the disease over time and contextualise the data gathered within the wider temporal framework. despite poorer preservation at the earlier sites, a reasonably high number of individuals were analysed for evidence of periodontal disease (table 1). table 2 shows the number of individuals included in the study by sex and age group. both medieval sites had proportionately different numbers of males and females in each age category. at 3-j -23 a greater number of females were assigned to the young adult category (n=22). at 3-j-18 a greater proportion of males were assigned to the middle adult category (n=31). sites h29 and r12 had roughly equal numbers in each sex and age group. where results have been divided by age and sex it should be noted that adolescents have been grouped into the young adult category while old adults have been grouped with middle adults. sex estimations of probable female and female have been grouped together, as have probable male and male individuals. these grouping meant that the numbers involved were larger and more representative of the whole. figure 1: map of the nile valley, from the first cataract to south of the confluence of the white and blue niles, demonstrating the location of sites h29 and r12. the region of the 4th cataract, including sites 3-j18 and 3-j-23, is also highlighted within the box and is shown in greater detail in figure 2. figure 2: map of the fourth cataract region, with the location of sites 3-j-18 and 3-j-23 shown. original image copyright of a. davies-barrett. sites n time period 3-j-18 111 late medieval (ad1100-1500) 3-j-23 69 early medieval (ad500-1000) h29 62 kerma ancien r12 70 neolithic total 312 table 1. sites included in the current study, number of individuals and time period for each site are given 32 dental anthropology 2019 │ volume 32 │ issue 02 these skeletal collections provide a unique opportunity to investigate periodontal disease in groups from a range of environmental, social, and cultural backgrounds. the neolithic period in nubia was characterised by semi-nomadic pastoralism combined with hunting and gathering (bard, 2008; gautier & van neer, 2011; hassan, 1986; l. krzyżaniak, 2004; wengrow et al., 2014). increasing social complexity may have led to a range in craftsmanship, much of which could have involved the use of the mouth and dentition (haaland, 1987; a. krzyżaniak, 2011; salvatori & usai, 2008a). during the kerma period, small sedentary groups appear to have formed and there is evidence for urbanisation and socioeconomic centralisation at the town of kerma (bonnet, 2004, 2010; chaix & grant, 1992). pastoralism remained an important part of cultural practice and was also accompanied by an increase in the cultivation of crops (chaix, 1984, 2007; grant, 2002; d. welsby, 1996). during the medieval period settlements consisted of larger rural and urban groups, with centralised socioeconomic control, in particular as part of the kingdom of makuria in upper nubia (godlewski, 2010; d. welsby, 2002; d. welsby & daniels, 1991). there is also a pattern of increasing aridity across the saharan region from the middle holocene (5000 bc) onwards (kuper & kröpelin, 2006; kuper et al., 2007; macklin & woodward, 2001; welsby, macklin, & woodward, 2002). before and during the neolithic, shifting rain-belts and higher humidity meant that upper nubia was a savannah-like environment and swamps and marshes may have been present, particularly in the areas surrounding the river, with paleochannels running into and around the main tributary of the nile. this wetter environment underwent progressive desertification and, by around 1500 bc, was similar to the desert landscape of modern northern sudan (kuper & kröpelin, 2006, p. 806). the sites examined here represent a range of ecological niches. 3-j-18 was located on mis island, within the rocky and changeable land of the fourth cataract, and nearby 3-j23 was situated on the banks of the nile (thomas, 2008; welsby, 2003, 2012). both h29 and r12 were in the northern dongola reach, further downstream than the fourth cataract, after the nile turns north towards the third cataract. site h29 was between the alfreda and hawawiya niles (paleochannels) (welsby, 2001; whiting, 2018) and r12 at the southern end of the seleim basin – a natural basin where water collected during high flood and rain fall (salvatori & usai, 2008b). differing environmental pressures and socio-cultural practices may have influenced the disease status, immune responses, behaviour, and diet of the individuals living in these different areas of the middle nile, which may have led to differences in the prevalence rate of periodontal disease. these collections allow for valuable site adolescent young adult middle adult old adult unknown age total r 1 2 male 4 6 12 22 female 1 4 3 3 11 indt. sex 2 2 33 37 total 1 (1.4%) 10 (14.3%) 11 (15.7%) (0.0%) 48 (68.6%) 70 h 2 9 male 8 9 2 19 female 10 6 12 28 indt. sex 2 2 1 10 15 total 2 (3.2%) 20 (32.2%) 16 (25.8%) (0.0%) 26 (38.8%) 62 3 -j-2 3 male 1 10 13 1 25 female 2 20 10 1 33 indt. sex 2 3 3 3 11 total 5 (7.2%) 33 (47.8%) 26 (37.8) (0.0%) 5 (7.2%) 69 3 -j-1 8 male 15 30 1 1 47 female 6 23 21 2 3 55 indt. sex 1 5 1 2 9 total 7 (6.4%) 43 (38.7%) 52 (46.8%) 3 (2.7%) 6 (5.4%) 111 table 2. age and sex distributions for each site 33 dental anthropology 2019 │ volume 32 │ issue 02 comparisons at key points in time that may reveal shifts in ‘oral health’ and disease load. results will also be compared with similar studies from around the globe, further aiding our modern understanding of the social, environmental and biological factors that affect susceptibility to periodontal disease and changes to the state of oral health over time. clinical and anthropological background periodontal disease is the result of the body’s immune response to the long-term presence of large numbers of microorganisms in dental plaque deposits on the teeth. it is a hypersensitive reaction in which the immune response damages the tissues of the periodontium. in their seminal paper, page and schroeder (1976) described the four stages of periodontal disease as they were understood at the time, the main notions of which are still relevant to this day: the initial lesion is described as inflammation and vascularisation involving infiltration of neutrophils (elements of the immune system) through the gingival tissue to the junctional epithelial cells lining the periodontal pocket (the periodontal pocket is formed around the tooth as the supporting tissues are destroyed). this is accompanied by movement of other immune elements such as t-cells, into the area but few b-cells. the early lesion sees a change to macrophage and t-cell domination with lymphocyte proliferation and the beginnings of a loss of connective tissue, such as the periodontal ligament. the established lesion involves further collagen (connective) degradation, detachment of the periodontal ligament and a clear increase in b -cell involvement. the advanced lesion is associated with alveolar bone loss and a further increase in b-cell proliferation. the authors also noted that the apical extension of junctional epithelial cells leads to an extension/ expansion of the periodontal pocket, and that a susceptible host was necessary for the progression of the disease at all stages. as observed by hajishengallis and korostoff (2017), these concepts are still correct and relevant today. advances since page and schroeder’s original paper include an increased understanding of the interaction of the innate and acquired immune system, as well as a greater appreciation of the role and “functional plasticity” or changeability of the role of neutrophils in the initiation of the immune response and progression to periodontitis (hajishengallis & korostoff, 2017, p. 119). this latter point highlights the importance of neutrophil homeostasis, with the related immunodeficiency or the overstimulation of these cells leading to destructive periodontitis (cekici et al., 2014; kornman, page, & tonetti, 1997). since page and schroeder’s work, a clearer understanding of the interactions and synergism of episodes of immune response and bone formation and resorption has also been made – a field known as osteoimmunology. this has shown that t-cells and b-cells express rankl (signalling protein) that contribute to the process of osteoclastogenesis, tipping the balance of bone homeostasis towards resorption (kikuta et al., 2013). many advancements in the understanding of this disease process were set out in a series of papers penned in part by one half (page) of the original duo of page and schroeder (darveau, tanner, & page, 1997; dennison & dyke, 1997; kornman et al., 1997). these subsequent papers highlight the dynamic nature of the disease as it goes through periods of progression and healing, with destructive lesions developing early on in life in some cases, or much later in others, and the role of host susceptibility in its progression. clinical methods used to record and monitor periodontal disease and gingivitis have changed little over the past decades. the study by belting, massler, and schour (1953), of over 5000 men from chicago, measured the distance between the cemento-enamel junction (cej) and the alveolar crest (ac) using a dental probe to determine the point of alveolar attachment within the periodontal pocket. a measurement of >2mm was deemed to indicate bone loss resulting from periodontal disease. additionally, gingival inflammation was recorded as bleeding/ presence of pus in the periodontal pocket. the world health-organization (2013) published a similar method to establish periodontal health that utilises the same kind of dental probe. gingival bleeding was scored as 0 (none) or 1 (bleeding upon insertion of probe), while periodontal pocket depth was assessed in increments: 0 (absence <3.5mm), 1 (4-5mm depth), 2 (≥6mm depth) (world-healthorganization, 2013, pp. 48-50). this clinical approach is commonly used to diagnose periodontal disease in both humans and animals (björnsson et al., 2003; person, 1961; tilakaratne et al., 2000; von wowern, klausen, & kollerup, 1994; watson, 1994). radiography has also been used to determine alveolar resorption. papapanou, wennström, and gröndahl (1988) looked for both ‘horizontal’ and ‘vertical’ bone loss. horizontal bone loss refers to the loss of height in the alveolar crest while maintaining a nor34 dental anthropology 2019 │ volume 32 │ issue 02 mal periodontal ligament space between root and socket. vertical bone loss denotes a morphological change in the vertical edges of the alveolar crest where the ligament space is expanded through vertical bone resorption (papapanou & wennström, 1991; papapanou et al., 1988; persson, rollender, laurell, & persson, 1998). in papapanou et al. (1988), the horizontal bone loss was recorded through the ac/cej measurement (after bjorn, hailing, and thyberg 1969). vertical bone loss was recorded as any morphological change seen as an oblique radiolucency ≥2mm apically from the highest point of the ac, with signs of bone resorption. similar techniques are still used in radiography to determine horizontal (bahrami, vaeth, wenzel, & isidor, 2017) and vertical bone loss (rams, listgarten, & slots, 2018). these clinical methods, including the concept of horizontal and vertical bone loss, have been adapted in human bioarchaeology when only the bones of the jaws and the teeth survive (davies & picton, 1969; davies, picton, & alexander, 1969). in particular, the measurement between the cej and ac (after russell 1956) proposed that ac levels of more or less than half the length of the root may indicate horizontal bone loss at different stages. the results are often averaged across the mouth to obtain a tooth cervical height index (tch index). initially, davies et al. (1969) compared tch index results to visual examination in the same individuals, concluding that a measurement >2.5mm suggests alveolar bone loss consistent with periodontal disease. this compares well with modern radiographic standards of >3mm (bahrami et al., 2017) or >1.9mm (hausmann, allen, & clerehugh, 1991; persson et al., 1998), but less than manual examination suggested in the who standard of >3.5mm (world-health-organization, 2013). the measurement of horizontal bone loss (ac/cej distance) has been taken up by many anthropologists and archaeologists (for example, alexandersen, 1967; eshed, gopher, & hershkovitz, 2006; lavigne & molto, 1995; lukacs, 1989; masotti et al., 2013; meller et al., 2009). however, this empirical method of measurement, which appears to be an objective, repeatable, and straightforward approach, bears a fundamental problem when applied to skeletal remains. as demonstrated by levers and darling (1983), murphy (1959), and newman and levers (1979), extensive occlusal wear can lead to the continuous eruption of a tooth to maintain an occlusal plane, extending cej/ac distance independently of alveolar resorption and periodontal disease. davies and picton (1969), two of the first to apply this method to archaeological remains, noted the impact of attrition on ac/cej distance; as attrition increased, so did the measurement. in a second paper, davies and picton (1969b) discuss the link between ac/cej distance and dental wear, while rarely referring to pathological change related to periodontal disease. watson (1986) also demonstrated a clear correlation between increasing ac/cej distance and dental wear in anglo saxon to tudor individuals. however, each of these papers referred to this process as ‘alveolar recession’ rather than the extension of the ac/cej distance (due to continuous eruption). it may be the misunderstanding of this term that has led to the persistent of the use of the ac/cej measurement to record alveolar resorption connected to periodontal disease in skeletal remains. in archaeological collections – where dental wear is ubiquitous – measurement between the ac and cej is unreliable and unsuitable. lavigne and molto (1995, p. 269), cited by many as a basis for the technique, quite clearly stated that “the relationship of dental wear and over-eruption is not considered in the development of this system”. for example, eshed et al. (2006) noted a higher prevalence of horizontal bone loss in natufian remains, interpreted as indicative of a higher prevalence of periodontal disease. however, high levels of dental wear were also recorded in this group, which is likely to have impacted the results and interpretations of the periodontal disease prevalence. it is unfortunate that, without the presence of soft tissue, this straightforward method, so useful in modern clinical research, cannot be applied to archaeological material due to the impact of dental wear. this is particularly true of ancient populations, where dental wear was almost ubiquitous. although tried and tested, measuring horizontal bone loss is not an appropriate approach in archaeological populations with high dental wear. however, observation of vertical bone loss has also been utilised in archaeology. this approach assesses morphological changes and the vertical loss of bone around the tooth root(s), thus recording changes in the contour (rather than height) of the interdental alveolar crest. such changes are often recorded in clinical research (hausmann et al., 1991; papapanou et al., 1988; persson et al., 1998; rams et al., 2018), with perhaps the clearest definition made by papapanou et al. (1988): any morphological change seen as an oblique radiolucency in a radiograph, extending apically beside the tooth root, from the highest point of the ac, with signs of bone resorption. in archaeology, the most commonly used method for recording vertical bone loss was developed by kerr (1988). kerr recognised the fundamental problem of using the ac/cej distance in archaeological material, stating that such measurements “do not adequately observe the disease entity they purport to” (kerr, 1986, p. 191). kerr followed on from work started by costa (1982), recording altered bone architecture, looking at infra-bony pockets and porosity (termed osteoporosis by costa). costa, however, had not accounted for the episodic nature of the disease, 35 dental anthropology 2019 │ volume 32 │ issue 02 instead implying that it was progressive. in 1988, kerr examined the aberdeen carmelite archaeological remains, drawing close parallels to histological changes seen in modern clinical sections of alveolar bone with periodontal disease at various stages. from this work, kerr created the following interdental septum/alveolar crest) scores (adapted from kerr 1988): 0. unrecordable. tooth on either side of the septum lost ante-mortem or the septum damaged postmortem 1. septal form characteristic of its region (convex in incisor region, grading to flat in the molar region). the cortical surface is smooth and virtually uninterrupted by foramina, depressions or grooves. 2. septal form characteristic of the region. cortical surface showing a range of morphology, from many small foramina/shallow grooves to a cortical surface showing larger foramina and/or prominent grooves or ridges. 3. septal form showing breakdown of contour with bone loss in the form of a shallow depression extending across the interspace from the buccal to lingual aspect, or as one or more smaller discrete areas of bone destruction, the essential and distinguishing features being a sharp and ragged texture to the bone. 4. septal form showing breakdown of contour with bone loss similar to that seen in score 3, the essential difference being the bone surface. instead of being ragged in appearance, the bone has a porous or smooth honeycomb effect with all defects rounded. 5. presence of deep infra-bony defect with sides sloping at 45 degrees or more and with a depth of 3mm or more. the surface may be sharp and ragged or smooth and honeycombed. clinical measurements tend to focus on the periodontal pocket depth (gingival margin/ac) and attachment loss (cej/ac). in archaeological material, the absence of soft tissue (or, if present, highly altered) prevents an assessment of the pocket depth. in kerr’s system – although not a measurement – attachment loss is indicated in scores 3 to 5, where the original architectural contour of the bone has been lost. whether seen as a shallow change (score 3), a deep pocket (score 5), or a quiescent (healing) phase (score 4), this would ‘clinically’ be recorded as an attachment loss and measured by probing. therefore, it may be possible to compare the prevalence of kerr scores 3 to 5 with that of attachment loss – independent of the extent – recorded in modern clinical data. comparing kerr scores 3 to 5 with radiographic data poses a greater problem. many papers mention the limitations of visually examining radiographs as they may only show demineralisation in bone once it has reached 30-50% or more (page & eke, 2007; research-science-therapy-committee, 2003). thus, subtle changes (i.e. kerr scores 2 or 3) may, perhaps, not easily be detected in radiographs; particularly the slight changes in vascularity proposed with gingivitis (see below). however, the recent use of subtraction imaging might compare well with kerr’s earlier stages, with demineralisations as low as 5% being detected (gröndahl & gröndahl, 1983). however, subtraction imaging techniques focus on treatment rather than diagnosis (corbet, ho, & lai, 2009; page & eke, 2007; research-sciencetherapy-committee, 2003) and do not include scores or stage-like evaluations, making like-for-like comparisons difficult. the higher kerr scores, such as 4 or 5, indicate clearer vertical bone loss. score 4 the ‘quiescent’ phase is likely to correspond to the periods of healing or reduced inflammation seen by page and schroeder (1976), reflecting the dynamic nature of periodontal disease. radiographs published by fish (1948, pp. 388, figure 175), for example, show a case of kerr scores 4 or 5 (dependent on depth no scale given) with a deep angular defect with smooth edges visible on the radiograph. perhaps most controversially, kerr (1988) argues that gingivitis may be recognised in the alveolar bone (score 2). prior to kerr’s work, and since its publication, researchers have suggested that the initial inflammation only effects the soft tissues and cannot be detected in archaeological material as it involves no loss of attachment (page & schroeder, 1976; schwartz et al., 1997). however, kerr suggests that the porosity frequently seen in the alveolar crest (costa, 1982; kerr, 1986, 1988) reflects the increased vascularisation associated with gingival inflammation in gingivitis (hajishengallis & korostoff, 2017; page & schroeder, 1976). in chronic gingivitis, neutrophils have the ability to influence the bone remodelling process (page & schroeder, 1976; schwartz et al., 1997); however, schwartz et al. (1997) note that ultrastructural changes in bone do not occur in gingivitis only as it progresses to periodontal disease. this is not supported by earlier research from kennedy (1974), hausmann, ortman, and sedransk (1979), and heijl, rifkin, and zander (1976); and, the paper by schwartz et al. (1997) may actually be referring to the structural resorption of bone and the loss of attachment, rather than remodelling to account for increased vascularity as kerr has suggested. indeed, kennedy (1974) found that with gingivitis there was a significant increase in vascularity after only 2 weeks, including an increased number of vessels perforating the alveolar crest. hausmann et al. (1979) supports this finding, revealing a decrease in alveolar bone mass using 125i 36 dental anthropology 2019 │ volume 32 │ issue 02 absorptiometry in cases of gingivitis in monkeys. heijl et al. (1976) and kennedy and polson (1973)also found increases in osteoclast activity and bone loss and remodelling in cases of induced gingivitis. while these studies support kerr’s idea, further clinical and radiological work may be required to clarify the impact of gingivitis on the alveolar crest. the subtle loss of bone density associated with the remodelling of the alveolar crest, when there is no attachment loss, is unlikely to be seen radiographically without the aid of subtraction imaging. yet some histological studies support kerr’s findings. fish (1948), in a comprehensive study of the surgical pathology of the mouth, showed that osteoclast activity had resorbed bone prior to any loss of attachment (fish, 1948, pp. 317,331). kronfeld (1933) also found that inflammation of the gingival tissue, with little to no attachment loss, was accompanied by some resorption of alveolar bone (kronfeld, 1933, pp. 309, figure 249). kerr’s (1988) method allows the recording of vertical bone loss in archaeological material. though subjective, it is clearly defined and parallels clinical, radiographic, and histological understanding of both gingivitis and periodontal disease. it was developed to allow for detailed and meaningful comparisons between past and present prevalence of periodontal disease (kerr, 1986), and thus was employed as the most appropriate method for recording periodontal disease in the current study. methods age and sex have been shown to affect the prevalence of periodontal disease and gingivitis (amar & chung, 1994; kinane, podmore, & ebersole, 2001; löe, 1965; page & schroeder, 1976; shiau & reynolds, 2010; ziskin & nesse, 1946). in this study, age was recorded using the stages of pubic symphysis (brooks & suchey, 1990) and auricular surface (lovejoy etal., 1985) joint degeneration. sex was recorded using sexually dimorphic features of the skull and pelvis, after acsádi, nemeskéri, and balás (1970) (nuchal crest, mental eminence, glabella, orbital margin, mastoid process), phenice (1969) (ventral arc, sub-pubic concavity, ischiopubic ramus ridge), buikstra and ubelaker (1994) (greater sciatic notch), and rogers and saunders (1994) (pubic body shape). the following categories were used: sex: male; male?; undetermined; female?; female age: adolescent < 20 years (with third molars in occlusion); young adult 20-34 years; middle adult 35-49 years; old adult 50+ years; adult 20+ (age not assigned) pathological changes to the periodontium were recorded using the kerr (1988) method described above, scoring vertical bone loss through changes in the texture and contour of the interdental alveolar crest. these changes were observed using a good light source and a 10x magnification hand-lens. an example of the changes associated with each of kerr’s scores can be seen in figure 3. results are divided into three alveolar regions: the anterior region comprising the alveolar crests between the left mesial canine and right mesial canine; the premolar region from the mesial first premolar to the mesial second premolar; and the molar region from the mesial first molar to mesial third molar. this approach records the distribution of pathological changes across the mouth and takes into account preservation bias (antoine, 2017). upper and lower dentitions were grouped together for the purpose of this study. unobservable interdental septa were accounted for, allowing a true prevalence to be calculated for each group and the results are divided by age and sex (individuals assigned to the ‘probable male’ or ‘probable female’ categories were combined with those in the ‘male’ and ‘female’ categories respectively). the 95% confidence intervals were calculated, as well as the confidence interval of difference (cid), which shows a true statistical difference in prevalence when the confidence interval range does not pass through zero (altman, 2000). additionally, the more traditional fisher’s exact test (two-tailed) was used to provide a further test of statistical significance. a p-value of <0.05 was used to identify significant differences between groups. intra-observer error for kerr’s (1988) scoring method was tested on 60 interdental alveolar crests. these data were divided by score 0 (unobservable), score 1 (no pathological change), score 2 (porosity) and scores 3-5 (vertical bone loss). table 3 shows the crosstabulation for the two intra-observations. intraobservations matched in 53/60 instances. cohen’s ĸ test showed good agreement between observations (according to altman, 1999), with ĸ= 0.765 and p= <0.0005, demonstrating significant agreement between observations. table 4 shows the crosstabulation for the two inter-observations. interobservations matched in 52/60 instances. cohen’s ĸ test showed good agreement between observations (according to altman, 1999), with ĸ= 0.800 and p= <0.0005, demonstrating a significant agreement between observations. the majority of error seen in the intra and interobservations were between scores 1 and 2, the difference between no pathological changes and increased porosity. the application of more light and better magnification was used to limit this error. however, this distinction is problematic. a minimal amount of porosity may be present in bone that has neither gin37 dental anthropology 2019 │ volume 32 │ issue 02 givitis nor periodontal disease (berkovitz, holland, & moxham, 1977, p. 191) and this limitation should be taken into account when interpreting results. results clear differences in the prevalence of kerr scores 3-5 can be seen between the assemblages examined (figure 4). site r12 (neolithic) has the lowest prevalence of all the sites in all tooth classes and for both sexes, as well as in its overall prevalence. the only exception is the anterior region of male jaws, which shows a kerr score 3-5 prevalence of 0% of interdental alveolar crests (ci 0-18) at r12 and at h29 (ci 011). the late medieval site of 3-j-18 has the second lowest prevalence at 6.7% (ci 4.6-9.7) for kerr scores 3-5. again, this is seen in all tooth classes, for both sexes, and overall (with the previous exception applying). conversely, the medieval site of 3-j-23 shows the highest prevalence in all tooth classes for both sexes and overall. the highest prevalence is that of the molar region of male individuals, with 47.5% (ci 41.1-53.6) of all interdental alveolar bone showing pathological change consistent with kerr scores 3-5. the prevalence at site h29 falls between those of the two medieval sites. tables 5-10 demonstrate the statistically significant differences between all sites in all tooth regions, with only two exceptions. the interdental bone in the premolar region of sites h29 and 3-j-23 do not show a statistically significant difference. here 16.2% (ci 12.1-22.7) and 20.2% (ci 16.9-24) were recorded, respectively. the difference in prevalence between these sites is 3.5% (cid -9.5 to 3.4, p=0.3300). the interdental bone in the anterior region from sites r12 and 3-j-18 also show no significant difference. here 0.0% (ci 0.0-5.3) and 3.3% (ci 2.3-4.6) were recorded, respectively. the difference in prevalence between these sites is 3.3% (cid -4.6 to 2.1 p=0.2617). distribution comparison in both male and female individuals, as well as overall, each site shows a similar distribution of kerr figure 3. examples of the different kerr stages from the current study: top left score 1 septal form characteristic of its region with no pathological change; top right score 2 septal form characteristic of the region. cortical surface showing a range of morphologies, from many small foramina/shallow grooves to a cortical surface showing larger foramina and/or prominent grooves or ridges; middle left – score 3 septal form showing breakdown of contour with bone loss in the form of a shallow depression extending across the interspace from the buccal to lingual aspect, or as one or more smaller discrete areas of bone destruction, the essential and distinguishing features being a sharp and ragged texture to the bone; middle right score 4 septal form showing breakdown of contour with bone loss similar to that seen in score 3, however, instead of being ragged in appearance, the bone has a porous or smooth honeycomb appearance; bottom left – score 5 presence of deep infra-bony defect with sides sloping at 45 degrees or more and with a depth of 3mm or more. the surface may be sharp and ragged or smooth. photographs by r. whiting, courtesy of the trustees of the british museum. 38 dental anthropology 2019 │ volume 32 │ issue 02 table 3. crosstabulation for intra-observer error for observations of kerr scores. numbers indicate counts of the kerr scores allocated in observation #1 and #2. observation#2 unobservable kerr 1 kerr 2 kerr 3-5 total o b se rv a tio n # 1 unobservable 13 0 0 0 13 kerr 1 0 37 4 3 44 kerr 2 0 0 2 0 2 kerr 3-5 0 0 0 1 1 total 13 37 6 4 60 observer#2 unobservable kerr 1 kerr 2 kerr 3-5 total o b se rv e r# 1 unobservable 6 0 0 1 7 kerr 1 0 24 3 0 27 kerr 2 0 3 16 0 19 kerr 3-5 0 0 1 6 7 total 6 27 20 7 60 table 4. crosstabulation for inter-observer error observations for periodontal disease recording. numbers indicate counts of the kerr scores allocated by observer #1 and #2. figure 4: box and whisker plot showing the prevalence of periodontal disease at sites r12, h29, 3-j-23 and 3j-18. box plot indicates prevalence in each tooth region. whiskers indicate the confidence intervals for each group based on the calculations set out in altman, machin, bryant, and gardner (2000, p. 47). 39 dental anthropology 2019 │ volume 32 │ issue 02 table 7: site comparisons between r12 and 3-j-18 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. r12/3-j-18 anterior teeth premolars molars total raw data 0/68 (0.0%) 31/939 (3.3%) 0/128 (0.0%) 45/788 (6%) 20/232 (8.6%) 203/1063 (19%) 20/428 (4.7%) 279/2790 (10%) cid -4.6 (-3.3) 2.1 -7.6 (-5.70 -2.5 -14.3 (-10.5) -5.6 -7.3 (-5.3) -2.7 fisher’s exact test p=0.2617 p=0.0015 p=0.0001 p=0.0002 table 8: site comparisons between h29 and 3-j-23 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. h29/3-j-23 anterior teeth premolars molars total raw data 8/108 (7.4%) 101/559 (18%) 32/191 (16.7%) 97/480 (20.2%) 68/241 (28.2%) 251/640 (39.2%) 108/540 (20%) 449/1679 (26.7%) cid -15.6 (-10.7) -3.5 -9.5 (-3.5) 3.4 -17.6 (-11.0) -4.0 -10.9 (-6.7) -2.6 fisher’s exact test p=0.0044 p=0.3300 p=0.0028 p=0.0017 table 9: site comparisons between h29 and 3-j-18 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. h29/3-j-18 anterior teeth premolars molars total raw data 8/108 (7.4%) 31/939 (3.3%) 32/191 (16.7%) 45/788 (6%) 68/241 (28.2%) 203/1063 (19%) 108/540 (20%) 279/2790 (10%) cid 0.3 (4.1) 10.7 6.1 (11.0) 17.1 3.3 (9.1) 15.5 6.6 (10.0) 13.7 fisher’s exact test p=0.0529 p=<0.0001 p=0.0021 p=<0.0001 r12/3-j-23 anterior teeth premolars molars total raw data 0/68 (0.0%) 101/559 (18%) 0/128 (0.0%) 97/480 (20.2%) 20/232 (8.6%) 251/640 (39.2%) 20/428 (4.7%) 449/1679 (26.7%) cid -21.5 (-18.1) -12.0 -24.0 (-20.2) -15.8 -35.5 (-30.6) -24.9 -24.8 (-22.1) -18.9 fisher’s exact test p=<0.00001 p=<0.00001 p=<0.00001 p=<0.00001 table 6: site comparisons between r12 and 3-j-23 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. r12/h29 anterior teeth premolars molars total raw data 0/68 (0.0%) 8/108 (7.4%) 0/128 (0.0%) 32/191 (16.7%) 20/232 (8.6%) 68/241 (28.2%) 20/428 (4.7%) 108/540 (20%) cid -13.9 (-7.4) -1.0 -22.7 (-16.8) -11.3 -26.3 (-19.6) -12.8 -19.3 (-15.3) -11.3 fisher’s exact test p=0.0239 p=<0.00001 p=<0.00001 p=<0.00001 table 5: site comparisons between r12 and h29 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 40 dental anthropology 2019 │ volume 32 │ issue 02 scores 3-5. the anterior region of the jaws has the lowest prevalence, followed by the premolar region, with the molar region displaying the highest prevalence in every site. in male individuals from both medieval sites (3-j-18 and 3-j-23), a similar prevalence is present in the anterior and premolar regions. overall, the premolars from site 3-j-23 show a 4.8% higher prevalence than the anterior region (cid -13.5 to 3.7, p=0.2966), while at site 3-j-18, there is a difference of 0.6% between the tooth regions (cid -4.6 to 3.2, p=0.7684). in contrast, there is a statistically significant difference in prevalence between the anterior and premolar regions in the males from site h29 – 15% (cid -26.1 to -2.0, p=0.0254). the difference in prevalence between the anterior and premolar regions at all three sites is less pronounced in female individuals (figure 5). at r12, kerr scores 3-5 are only found in the molar region, this was true of both sexes and in overall prevalence. comparisons of age and sex figure 5 shows the prevalence of kerr scores 3-5 in each of the groups examined, divided by age and sex. in nearly every tooth region of each assemblage, the middle adult category shows a higher prevalence of kerr scores 3-5 than the young adults– with the exception of the premolar region at h29 where young adult males show a slightly higher prevalence than middle adult males. however, not all these differences are statistically significant (tables 11-18). in fact, in the earlier periods, the neolithic and kerma groups show no statistical significance between age categories for either sex. yet, in the medieval groups, middle adults show a statistically higher prevalence than young adults in every tooth region for male individuals. however, this is not the case for female individuals, where a statistical difference between age categories is only seen in the molar region at 3-j18, and in the molars and premolars at 3-j-23. in addition, middle adult males, at both medieval sites, show a significantly higher prevalence of kerr scores 3-5 than middle adult females in the anterior dentition. discussion the sites examined in this study reveal a wide range in the prevalence of kerr scores 3 to 5 (from 4.7% at r12 to 26% at 3-j-23), which represents destructive bone loss relating to periodontal disease (kerr, 1988). in modern populations from across the globe, p. e. petersen (2003) reports periodontal disease ranging from 5 to 15%. petersen’s data, however, only include individuals with periodontal pockets ≥6mm, and cannot be directly compared with the higher prevalence rates reported here as the latter include a greater range of periodontal remodelling. the current study also differs in that it records changes per interdental septum rather than per individual. it should be noted that due to varying levels of preservation, the numbers of individuals with age-at-death and sex estimates were small at sites r12 and h29, but relatively large at the two medieval sites. the results from these earlier sites are thus less likely to be as representative as those from the later sites. the neolithic site of r12 shows the lowest prevalence of periodontal disease in all tooth regions and overall for males, females, and both age categories. periodontal disease is only present in the molar region, with none observed in the anterior or premolar teeth. prevalence at h29 is higher than that of r12, with pathological changes found in all regions of the dentition. site 3-j-23 has considerably higher prevalence rates than both r12 and h29. however, at the later medieval site of 3-j-18, prevalence rates are lower than those at both the earlier medieval and kerma ancien sites. current understanding of the biological processes contributing to periodontal disease suggest that a range of factors can contribute to the initiation and progression of the condition. its association with systemic inflammation is particularly relevant here (barnett, 2006; page, 1998; p. e. petersen et al., 2005; thoden van velzen, abraham‐ inpijn, & moorer, 1984), with greater inflammation in the body causing susceptibility to the hypersensitive response involved in periodontal disease and vice versa. the archaeological record suggests that during the neolithic period, settlement may have been more temporary and communities more mobile, in part due to the more humid environment and table 10: site comparisons between 3-j-23 and 3-j-18 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 3-j-23/3-j-18 anterior teeth premolars molars total raw data 101/559 (18%) 31/939 (3.3%) 97/480 (10.2%) 45/788 (6%) 251/640 (39.2%) 203/1063 (19%) 449/1679 (26.7%) 279/2790 (10%) cid 11.5 (14.8) 18.3 10.7 (14.5) 18.6 15.7 (20.1) 24.6 14.4 (16.7) 19.2 fisher’s exact test p=0.00001 p=<0.00001 p=<0.00001 p=<0.00001 41 dental anthropology 2019 │ volume 32 │ issue 02 figure 5. box and whisker plot showing the prevalence of periodontal disease at sites r12, h29, 3-j23 and 3-j-18. box plot indicates prevalence in each tooth region, for young and middle adult males and females. whiskers indicate the confidence intervals for each group based on the calculations set out in altman et al. (2000, p. 47). table 11: comparisons between young and middle adult males at r12 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. r12 males anterior teeth premolars molars total raw data (young adults) (middle adults) 0/5 (0.0%) 0/1 (0.0%) 0/11 (0.0%) 0/8 (0.0%) 0/21 (0.0%) 2/17 (11.8%) 0/37 (0.0%) 2/26 (7.7%) cid -79.3 (0.0%) 43.4 -32.4 (0.0) 25.9 -34.3 (-11.8) 5.9 -24.1 (-7.7) 3.2 fisher’s exact test p=1 p=1 p=0.19 p=0.16 table 12: comparisons between young and middle adult females at r12 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. r12 females anterior teeth premolars molars total raw data (young adults) (middle adults) 0/6 (0.0%) 0/8 (0.0%) 0/12 (0.0%) 0/9 (0.0%) 2/15 (13.5%) 2/18 (11.1%) 2/33 (6.0%) 2/35 (5.7%) cid -32.4 (0.0) 39.0 -32.4 (0.0) 24.3 -21.5 (2.2) 28.0 -13.3 (0.3) 14.5 fisher’s exact test p=1 p=1 p=1 p=1 42 dental anthropology 2019 │ volume 32 │ issue 02 table 13: comparisons between young and middle adult males at h29 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. h29 males anterior teeth premolars molars total raw data (young adults) (middle adults) 0/11 (0.0%) 0/20 (0.0%) 5/27 (18.5%) 4/33 (12.1%) 7/36 (19.4%) 15/38 (39.5%) 12/74 (16.2%) 19/91 (20.9%) cid -16.1 (0.0) 25.9 -12.0 (6.4) 26.0 -38.6 (-20.0) 0.8 -16.2 (-4.7) 7.6 fisher’s exact test p=1 p=0.71 p=0.07 p=0.54 table 14: comparisons between young and middle adult females at h29 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. h29 females anterior teeth premolars molars total raw data (young adults) (middle adults) 2/25 (8.0%) 2/11 (18.2%) 2/21 (9.5%) 3/24 (12.5%) 4/29 (13.8%) 11/36 (30.6%) 8/75 (10.6%) 16/71 (22.5%) cid -40.3 (-10.2) 11.2 22.3 (-3.0) 18.1 -35.1 (-16,8) 4.2 -24.0 (-11.9) 0.3 fisher’s exact test p=0.57 p=1 p=0.14 p=0.07 table 15: comparisons between young and middle adult males at 3-j-23 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 3-j-23 males anterior teeth premolars molars total raw data (young adults) (middle adults) 9/97 (9.3%) 40/116 (34.5%) 9/77 (11.7%) 40/96 (41.7%) 37/115 (32.2%) 71/116 (61.2%) 55/289 (19.0%) 151/328 (46.0%) cid -35.2 (-25.2) -14.3 -41.3 (-30.0) -17.0 -42.1 (-30.8) -18.0 -33.8 (-27.0) -19.8 fisher’s exact test p=<0.0001 p=<0.0001 p=<0.0001 p=<0.0001 table 16: comparisons between young and middle adult females at 3-j-23 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 3-j-23 females anterior teeth premolars molars total raw data (young adults) (middle adults) 20/182 (11.0%) 9/80 (11.3%) 16/148 (10.8%) 16/71 (22.5%) 53/206 (25.7%) 51/88 (58.0%) 89/536 (16.6%) 76/239 (31.7%) cid -9.8 (-0.3) 7.2 -23.4 (-11.7) -1.6 -43.4 (-32.2) -20.0 -22.0 (-15.2) -8.7 fisher’s exact test p=1 p=0.02 p=<0.0001 p=<0.0001 table 17: comparisons between young and middle adult males at 3-j-18 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 3-j-18 males anterior teeth premolars molars total raw data (young adults) (middle adults) 0/118 (0.0%) 26/260 (10.0%) 0/91 (0.0%) 23/216 (10.6%) 9/127 (7.1%) 81/291 (27.8%) 9/336 (2.6%) 130/767 (16.9%) cid -14.2 (-10.0) -5.6 -15.5 (-10.6) -5.3 -27.1 (-20.7) -13.2 -47.9 (-42.0) -35.9 fisher’s exact test p=<0.0001 p=0.0005 p=<0.0001 p=<0.0001 43 dental anthropology 2019 │ volume 32 │ issue 02 a reliance on pastoral cultural practices (bard, 2008; gautier & van neer, 2011; hassan, 1986; l. krzyżaniak, 2004; wengrow et al., 2014). at this time, population clusters may have been smaller and may have had less contact with other groups, limiting the spread of disease and systemic inflammation. this may in part explain the very low levels of periodontal disease prevalence in the neolithic group and the much higher levels in the later groups, particularly the medieval site of 3-j-23. unfortunately, none of the cemeteries examined in this study had associated settlements and occupation size or patterns could not be established. genetic susceptibility is also likely to affect the prevalence of periodontal disease (hajishengallis & korostoff, 2017; kornman & di giovine, 1998; kornman et al., 1997; laine, crielaard, & loos, 2012; page & schroeder, 1976). clinical studies have demonstrated that certain gene expressions influence patient susceptibility to both aggressive and chronic periodontal disease (kornman & di giovine, 1998; laine et al., 2012; offenbacher, barros, & beck, 2008). in the nile valley, elamin, skaug, ali, bakken, and albandar (2010) study of the periodontal status of table 18: comparisons between young and middle adult females at 3-j-18 for kerr scores 3-5 in each tooth region, as well as overall. raw data, confidence interval of difference (altman et al., 2000) and p-value for two-tailed fisher’s exact test are shown. significant values are shown in bold. 3-j-18 females anterior teeth premolars molars total raw data (young adults) (middle adults) 1/266 (0.4%) 2/191 (1.0%) 6/222 (2.75) 9/165 (5.5%) 37/306 (12.1%) 57/216 (26.4%) 44/794 (5.5%) 68/572 (11.8%) cid -2.1 (-0.3) 1.5 -7.6 (-2.8) 1.2 -21.3 (-14.3) -7.5 -9.6 (-6.3) -3.3 fisher’s exact test p=0.57 p=0.18 p=<0.0001 p=<0.0001 table 19: comparison of the male, female and overall kerr scores 3-5 recorded in this study with wasterlain et al. (2011) and kerr (1991). raw data and prevalence (%) are provided. site/study male female overall r12 7/141 (5%) 4/108 (3.7%) 20/428 (4.7%) h29 31/165 (18.7%) 45/246 (18.7%) 108/540 (20%) 3-j-23 214/639 (33.4%) 165/779 (21.1%) 449/1679 (26.7%) 3-j-18 140/1129 (12.4%) 119/1432 (8.3%) 279/2790 (10%) wasterlain et al. (2011) 773/4980 (14.7%) 602/4420 (13.6%) 1335/9400 (14.2%) kerr (1991) 702/3142 (22.3%) table 20: comparison of kerr scores 3-5 in this study and kerr (1991) . raw data and prevalence (%) provided by dental distribution anterior teeth premolars molars total r12 0/68 (0.0%) 0/128 (0.0%) 20/232 (8.6%) 20/428 (4.7%) h29 8/108 (7.4%) 32/191 (16.7%) 68/241 (28.2%) 108/540 (20%) 3-j-23 101/559 (18%) 97/480 (20.2%) 251/640 (39.2%) 449/1679 (26.7%) 3-j-18 31/939 (3.3%) 45/788 (6%) 203/1063 (19%) 279/2790 (10%) kerr (1991) 184/1041 (17.6%) 171/1047 (16.3%) 335/1339 (26.5%) 702/3142 (22.3%) 44 dental anthropology 2019 │ volume 32 │ issue 02 sudanese students concludes that african ethnicity and male sex are risk factors in young people aged 13-19 years. if individuals from site r12 had a very different genetic make-up to the other sites examined, this may explain some of the very different prevalence rates observed here. however, no adna studies have been made. the work by irish (2008), using dental morphology as a proxy to genetics, suggests a close biological affinity between r12 and other nubian groups of the time, as well as with groups from subsequent periods. however, dental morphological data is not currently available for h29 or the fourth cataract sites. few clinical studies have linked periodontal disease to diet (björnsson et al., 2003; person, 1961; watson, 1994). in sudan, the archaeological record suggests an agricultural transition or intensification between the neolithic and medieval periods (björnsson et al., 2003; chaix, 1984, 2007; clapham & rowley-conwy, 2007; fuller, 2004; fuller & edwards, 2001; iacumin et al., 1961; watson, 1994). an increase in consumption of grains during this period may have affected the make-up of the oral flora within the supra-gingival biofilm and, in turn, susceptibility to periodontal disease. when compared to wasterlain, cunha, and hillson (2011), which also used the kerr method on individuals of known age and sex from the coimbra collection in portugal, the overall prevalence for the coimbra post-industrial group (14.2%; ci 13.5-14.9) falls between that of the later medieval group from 3 -j-18 (10%; ci 8.9-11.2) and the kerma ancien group from h29 (20%;ci 16.8-23.6). the coimbra data also has a significantly higher prevalence than that of 3-j18 (4.2%; cid -5.5 to -2.8 p=<0.00001), as well as a significantly lower prevalence than h29 (5.8%; cid 2.6 to 9.4 p=0.0003). the coimbra data also have a statistically lower prevalence than 3-j-23 and a higher prevalence than r12. the results could not be directly compared to the medieval scottish collections (ad 900-1600) examined by kerr (1991; see table 19) due to its inclusion of sub adults. however, once kerr’s data is adjusted to exclude the sub-adults (table 19), periodontal disease was observed in 22.3% of interdental alveolar crests. this is 2.3% higher than the prevalence observed at h29 (cid 1.5 to 5.8 p=0.2378) and significantly higher than results from sites r12 (17.7%; cid 14.9 to 19.9 p=<0.00001) and 3-j-18 (12.3%; cid 10.5 to 14.2 p=<0.00001), as well as significantly lower than 3-j23. the middle nile valley data compares well with the range seen in other collections with the exception of r12, where prevalence is much lower than all other collections, and even lower than the range observed in modern populations (petersen, 2003). the medieval scottish data by kerr (1991) also show a prevalence of periodontal disease of 17.6% (ci 15.5-20.1) in the anterior region, 16.3% (ci 14.218.7) in the premolar region, and 26.5% (ci 24.2-28.9) in the molar region (table 20). prevalence rates in the premolar and molar regions are comparable with those found at site h29. however, the prevalence recorded in the anterior region was significantly higher than h29 (10.3%; cid -14.6 to -3.4 p=0.0044) and aligns more closely with that of 3-j-23. a similar distribution of periodontal disease across the mouth was found at coimbra and the sudanese sites, with a higher prevalence in the molar region and the lowest prevalence in the anterior region. some studies have found a close link between periodontal disease and dental hygiene (axelsson & lindhe, 1981; löe, 2000; p. e. petersen et al., 2005). in modern sudan, darout, albandar, and skaug (2000), found that miswak users a stick or root of the species salvadora persica with antibacterial properties used as a toothbrush across africa had less gingival bleeding in the molars than toothbrush users, as well as lower prevalence rates of ≥4mm pocketing and attachment loss. this study also found that the prevalence of attachment loss was higher in the posterior maxillary teeth, with the opposite true for the mandible. the use of the miswak appears to improve oral hygiene (halawany, 2012), most probably by cleaning the dental plaque away from the gums and reducing the microbial load. although little is known of dental hygiene practices in the neolithic, kerma, or medieval periods in nubia, the high prevalence seen in the molar region in these collections, as well as those of coimbra and scottish medieval period, may point to a similar problem. the molar region can be hard to clean of food and plaque, with deposits building faster or more readily than in other regions of the dentition (hillson, 2005). this would, in turn, differentially increase the microbial challenge and hypersensitive response of the host’s immune system (cekici et al., 2014; darveau et al., 1997; kornman et al., 1997), particularly in that part of the mouth. the neolithic and kerma sites, examined in this study, also show some differences between the sexes. at site r12, the young adult males show no signs of periodontal disease, with young adult females displaying interdental changes in the molars. at the kerma site h29, no periodontal disease was observed in the anterior teeth of both the young and middle adult males, while females present the condition in both age groups. due to poor preservation, few individuals from r12 and h29 could be assigned age and sex, and these results may not be representative of the assemblages. in all tooth regions, the middle adults from the medieval sites show a higher prevalence of periodontal disease in males than fe45 dental anthropology 2019 │ volume 32 │ issue 02 males. this difference is only statistically significant in the anterior teeth from both medieval sites (3-j-23: difference = 23.2%, cid 11.3 to 33.7 p=0.0002; 3-j-18: difference = 9.0%, cid 4.9 to 13.3 p=<0.0001) and in the premolars at site 3-j-23 (difference = 19.1%, cid 4.7 to 32.0 p=0.012). bar these differences, little appears to separate males and females at the medieval sites in either age category. this mirrors the findings from coimbra. using a 3x2 chi2 test with 2 degrees of freedom, wasterlain et al. (2011, p. 36) compared the number of interdental septa recorded as healthy, with gingivitis, and with destructive lesions between males and females. their results indicate that males were significantly more at risk of periodontal disease and gingivitis, and less likely to have ‘healthy’ interdental septa. however, this particular statistical test may hide the true cause of the difference between males and females. when considered separately, males showed a lower prevalence of healthy septa than females (24.1 % and 27.5% respectively; difference = 3.4%; cid -5.1 to -1.6 p=0.0002) and a higher prevalence of gingivitis than females (61.1% and 58.9% respectively; difference = 2.3%; cid 0.3 to 2.3 p=0.0253). conversely, periodontal disease showed a prevalence of 14.7% in males and 13.6% in females, a modest difference of 1.1% (cid -0.3 to 2.5 p=0.1312) that is not statistically significant. these results appear to indicate that males had a significantly lower prevalence of ‘healthy’ interdental septa and a significantly higher prevalence of septa with gingivitis, but similar levels of periodontal disease. males and females from coimbra, however, showed a significantly higher prevalence than observed at site r12 (males difference = 9.8%, cid 4.7 to 12.5 p=0.0006; females difference = 9.9%, cid 4.4 to 12.4 p=0.0014) and a significantly lower prevalence than recorded at site 3-j-23 (males difference = 18.8%, cid -22.6 to 18.1 p=<0.00001; females difference = 7.6%, cid -10.7 to -4.6 p=<0.00001). biological differences between the sexes may explain these variations in prevalence (curilović, mazor, & berchtold, 1977; hefti, engelberger, & büttner, 1981) and it has been suggested that female hormonal fluctuations may lead to a higher prevalence of periodontal disease (holm‐peedersen & löe, 1967). however, other studies do not support this finding (amar & chung, 1994; kinane et al., 2001; marshallday, stephens, & quigley jr, 1955; mealey & moritz, 2003; shiau & reynolds, 2010; sooriyamoorthy & gower, 1989). indeed, in the results presented here, females in the earlier periods show higher prevalence than males in certain areas of the mouth, however, these differences are not statistically significant and prevalence in other dental regions are similar between sexes. in the later medieval groups, it is male individuals who show statistically higher prevalence and progress to destructive periodontal bone loss more readily than females in the older age category, particularly in the anterior dentition. in older adults, kerr (1991) also noted a higher prevalence of scores denoting destructive periodontal disease and suggested these were probably a reflection of a “cumulative effect” (p. 353) rather than a greater susceptibility or risk with increasing age. in essence, after destructive bone loss occurs, the loss of attachment of the periodontal ligament means that the bone is not replaced (cochran, 2008; hienz, paliwal, & ivanovski, 2015; hillson, 2005). as age increases, there may be a cumulative effect whether or not the lesions are active. this cumulative effect may account for some of the differences seen between the young and middle adult age categories in the current study. however, these differences were not significant in the neolithic or kerma period assemblages, and prevalence was only significantly higher in middle adult males in both medieval collections. although a higher prevalence was sometimes seen in middle adult females in the medieval period, this was not true for every region of the dentition (see tables 15-18). in the groups examined, the results suggest that apart from in some medieval cases there is little difference in the risk of developing periodontal disease, nor its cumulative effects, with increasing age. many factors appear to contribute to the development, progression and thus the prevalence of periodontal disease. this equifinality is further confounded by the sporadic progression and recession of the disease. either acute or chronic progression may occur; leading to florid destruction of the alveolar bone (both localised or widespread) (hajishengallis & korostoff, 2017; page & schroeder, 1976). periods of healing can restore bone texture to a certain extent, or there may be retention of bone loss despite an area being in a quiescent phase, with no hypersensitivity or destructive activity (kerr, 1988; page & schroeder, 1976). page and schroeder (1976) noted that a progression from an ‘established lesion’ to an ‘advanced lesion’ may occur within a couple of weeks to several years. with a lack of patient history and the cumulative effects of an episodic disease, captured at the point of death, the role of periodontal disease on the concept of ‘oral health’ may be hard to apply in archaeological remains. instead, a mere snapshot of an individual’s state of ‘health’ is actually represented. as shown here, this ‘snapshot’ may vary in different parts of the mouth. standalone clinical studies also encounter this limitation and focus on recording a patient’s ‘periodontal status’, a term also used by kerr -perhaps in an attempt to capture the flitting nature of this complex disease. further data is required to contextualise the differ46 dental anthropology 2019 │ volume 32 │ issue 02 ences over time, and between sexes and ages observed here, such as the low prevalence of periodontal disease at the neolithic site of r12. the kerr method has been used in very few studies, despite appearing to offer the best route forward. the data presented in this study gives new insight into the periodontal status of the inhabitants of the middle nile region from the neolithic to medieval period. continued application of the kerr method in other archaeological assemblages from both the nile valley and farther afield may help to contextualise these findings further and advance current understanding of this complex disease. acknowledgements this project was kindly funded by an arts and humanities research council collaborative doctoral award for collaborative research between the british museum and university college london. photographic images of skeletal and dental elements are courtesy of the trustees of the british museum. we would also like to thank dr davies-barrett for assistance with editing and the use of illustrative material. references acsádi, g., nemeskéri, j., & balás, k. 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(1946). pregnancy gingivitis: history, classification, etiology. american journal of orthodontics and oral surgery, 32(6), a390-a432. mayes et a. 2009.2 73 there are four treponemal syndromes, as identified by their subspecies of treponematosis, the expression of which differs in relation to environment and, possibly, host responses. three of these syndromes can affect the skeleton, namely yaws (treponematosis pallidum subsp. pertenue), bejal or endemic syphilis (t.p. subsp. endemicum), and venereal syphilis (t.p. subsp. pallidum.), which includes congenital syphilis. in the living, a clinical diagnosis as to which treponemal syndrome a patient may have can be difficult (landrum et al., 2005). in cases where symptoms of one syndrome may mirror the other, dna analysis aids in differential diagnosis (centurion-lara et al., 1998; kolman et al., 1999; landrum et al., 2005). with archaeological specimens, a positive identification using genetic testing depends on the amount of available, viable dna. in circumstances where taphonomic change has affected dna viability, one must rely on skeletal changes. patterns of affected bones characteristic of syphilis do aid in diagnosis, but not every case follows the same pattern, thus complicating its identification in the archaeological record (ortner, 2003). the same has been true of congenital syphilis with one significant exception, the dentition appears to follow a specific pattern when affected. transmitted between mother and child during fetal development, congenital syphilis often creates malformations in the developing dentition. these changes to the teeth have been documented in the new world; however, these cases are, frequently, from historic or proto-historic settings (jacobi et al., 1992; hutchinson and richman, 2006). ortner (2003:274) poses the question, “does the bioarchaeological evidence address the issues of where and when the various syndromes developed?” there is evidence from both sides of the atlantic ocean of alledged cases of syphilis of considstigmata of congenital syphilis on a high status juvenile at yuguë, oaxaca, mexico arion t. mayes1, anamay melmed1, and sarah barber2 1department of anthropology, san diego state university, ca 92182 2department of anthropology, university of central florida, fl 32816 abstract presented here is a case study from mesoamerica whose dentition resembles the dental stigmata of others who have been described as having congenital syphilis. found with a green stone bracelet, this child was likely a high-status member of a pre-colombian population from the pacific coast of oaxaca, mexico (late terminal formative period, 150 bce – ce 250). while taphonomic changes precluded in-depth observations of the skeleton, dental traits such as plane-like hypoplastic defect and fournier’s molars are described and compared to previous studies. additionally, a two-tier system is introduced for describing dental malformations that may suggest either environmental variation in the bacterial assault or in host response. dental anthropology 2009;22(3):73-84. *correspondence to: arion t. mayes, department of anthropology, 5500 campanle drive, san diego state university, san diego, california 92182-6040. e-mail: amayes@mail.sdsu.edu erable antiquity (baker and armelagos, 1988; hillson et al., 1998; ortner, 2003; hutchinson and richman, 2006; lewis, 2007; walker et al., 2005), and these fuel debate as to its origins. the majority of physical evidence in the new world, with regard to congenital syphilis is weighted toward changes to the post-cranial elements, with little description of the teeth (hutchinson and richman 2006). powell and cook (2005) discuss 16 pre-contact north american specimens with evidence of treponematosis. included are two regions from the interior of mexico and four sites along the pacific coast namely, alaska, canada, california, and baja california, mexico. the origin for the individual under discussion is the pacific coastal site of yugüe, oaxaca, mexico. here, evidence is presented from a new world case of an individual whose patterns of dental change possibly reflect congenital syphilis. the condition of these archaeological remains restricts this analysis to the teeth and leaves few or no clues elsewhere in the skeletal remains. dental traits characteristic of this disease are described here and are compared to previous studies. dental malformations due to congenital syphilis recent studies on cuspal enamel hypoplasia (ceh) have focused on the disruption of the enamel matrix formation that occurs at the inception of crown development (ogden et al., 2007). such enamel defects are 74 fig. 1. labial view of the central maxillary incisors showing patchy hypoplastic defects on the midcrown (right central incisor) and a heart-shaped incisal outline of the crown (left central incisor). the specimen’s left maxillary central incisor is on the right of the photograph; the right central is on the left. scale is in millimeters. fig. 2. lingual view of the central maxillary incisors showing their left-right asymmetry and a heart-shaped incisal portion of the right crown. scale in millimeters. fig. 3. occlusal view of the central maxillary incisors showing a patchy hypoplastic defect (labial of right central) and a heart-shaped incisal portion of the crown (left central incisor). scale in millimeters. fig. 4. lateral view of the left maxillary canine showing the occlusal crown reduction due to extended hypoplastic defect. scale in millimeters. significant because of their timing, as well as their potential association with certain diseases. one such disease is congenital syphilis (jacobi et al., 1992; hillson et al., 1998). congenital syphilis is not always detected at birth, as many of its clinical signs develop later (mansilla and pijoan, 1995), or, as in the case of the dentition, are not revealed until emergence (hillson et al., 1998). generally, skeletal markers such as bossing of the frontal bone, deformation of the nasal area, and inflammation of the tibia, known as sabre shin (mansilla and pijoan, 1995; hillson et al., 1998; ortner, 2003), are used to identify congenital syphilis in archaeological collections. however, dental defects such as hutchinson’s incisors, extreme linear enamel hypoplastic defects, transverse pitting in the enamel, moon’s molars, and mulberry molars also are considered symptomatic of the disease (jacobi et al., 1992; hillson et al., 1998; ortner, 2003). in archaeological collections, dental stigmata are valuable for diagnosing congenital a.t. mayes et al. 75 fig. 5. labial view of left maxillary canine showing occlusal crown reduction due to hypoplastic defects. scale in millimeters. fig. 6. occlusal view of the maxillary teeth, showing the change in tooth shape of the central maxillary incisors, and the left maxillary canine. from the left, the teeth are the specimen’s right first premolar, right central incisor, left central incisor, left canine, and left first premolar. fig. 7. occlusal view permanent lower right first molar with reduced irregular cusps and a circumferential plane-like defect (arrows). fig. 8. distal view of permanent lower right first molar showing circumferential plane-like defect with reduced crown size on coronal portion of the crown. syphilis because enamel does not remodel (as opposed to bone), and because enamel preserves well. a review of the literature, including case studies from historical, ancient, new world, and old world groups, reveals a two-tier pattern of developmental defects resulting in the described dental stigmata. the first tier, or level i defect pattern is a result of the genetic timing of tooth development; the second tier, or level ii defects, is an outcome of the environmental expression or, possibly, host response of particular stigmata. hillson and colleagues (1998:30) succinctly summarize the four most prominently known changes to the permanent dentition associated with congenital syphilis. here they are represented by examples in form from the present case study. note that the level i conditions follow an identifiable pattern both in cases of known syphilis and archaeological specimens, with slight variation in form for the level ii conditions in reference to the presentation of morphology. 1. “hutchinson’s incisors primarily seen in permanent upper first incisors, but sometimes also in some permanent lower central and lateral incisors (never in permanent upper lateral incisors or canines). showing a shortened incisal edge, with the mesial dental defects at yuguë, mexico 76 fig. 9. occlusal view of permanent right maxillary first molar (bottom) with reduced, irregular cusp and plane-like enamel defect. fig. 10. interrupted circumferential plane-like defect on the first permanent molar (lingual view). fig. 11. occlusal view of permanent left mandibular first molar (left) with circumferential plane-like defect. fig. 12. interrupted circumferential plane-like defect on the first permanent molar (buccal view; mesial is to the right of the photograph). and distal crown sides bulging out below it, and marked by a notch of variable shape” (figs. 1-3). 2. “permanent upper or lower canines with a sharp groove-like hypoplastic defect around the tip of their single” cusp (figs. 4-6). 3. “moon’s molars, or bud molars. only affecting upper and lower permanent first molars. all cusps are abnormally closely spaced, giving a narrow occlusal area relative to the bulge of the crown sides” (figs. 7-8). 4. “fournier molars, or more commonly mulberry molars. also only affecting permanent first molars. showing a marked plane-form hypoplastic defect, cutting sharply into the bases of all the cusps” (figs. 9-13). the age range for crown defect for the individual presented here is birth to 1.5 years (goodman and rose, 1990) to 1.9 years (reid and dean, 2006). case study burial 10 – individual 11 archaeological context the presence of these dental stigmata in a juvenile buried at the pre-columbian site of yugüe in the mexican state of oaxaca are discussed. occupied from the middle formative period (700 – 400 bce) until the late terminal a.t. mayes et al. 77 formative period (ce 100 – 250), yugüe is a 9.75 hectare site located on the floodplain of the lower río verde valley on oaxaca’s western pacific coast. the site was reoccupied in the late post-classic period (ce 1200 – 1522) and persists as a small hamlet today. historic and modern construction at the site has had a detrimental effect on buried human remains from the site, as discussed below. the core of formative period yugüe was a 10 m high monumental earthen platform, first constructed around 150 bce, that supported domestic and ceremonial architecture (barber, 2005; joyce, 1999). the summit of the platform was used for community ceremonial practices, including temple construction, burial, caching, and feasting (barber, 2005). today, a modern chapel sits atop the platform. burial 10 individual 11 (b10-i11), the focus of this report, was part of a temporally and spatially distinct cemetery dating to the late terminal formative (fig. 14). the cemetery contained at least 44 individuals densely-packed into an area of less than 7 m². only three individuals were fully articulated; the rest had been disturbed by the internment of later burials, and some may have been secondary burials. b10-i11 is among those that had been disturbed by later burials. the lower half of the individual’s skeleton was either removed or displaced by the later internment of at least two individuals. individuals’ ages within the cemetery ranged from neonate to elderly adult, with both males and females represented. in general, adults were buried in an extended position, placed on their right sides, with their heads to the west. juveniles were placed perpendicular to the adults, lying on their left sides, with their heads to the south. there were some exceptions to this pattern, particularly among individuals who had been severely disturbed by subsequent internments (mayes and barber, 2008). the burial fill contained a number of offerings, particularly miniature ceramic vessels and potsherds, most of which could not be directly associated with a particular individual. in a few cases, associated artifacts did indicate that certain individuals were of higher social status than others in the cemetery (barber, 2005; mayes and barber 2008). b10-i11 is one such case, as the individual was buried holding a long strand of green and white stone beads in the right hand. the presence of this socially valuable item has led investigators to suggest that b10-i11 was of high status (barber, 2005). burial description an inventory of remains revealed that the vault and lateral portions of the skull are present. however, the face is crushed with elements identified only as being bone, not allowing for any description of morphology or identification of pathological changes. the frontal, parietal, occipital, temporal, and zygomatic bones are present, with the left sides in fairly good condition, and the right sides crushed and fragmented. there is a partial left portion of the sphenoid, but with the right side missing. both the maxillae are fragmented, and the nasal and palatine bones are absent. the mandible is present but fragmentary. the lower limbs are missing, but the upper body is represented by the fragmented remains of the distal left humerus, a partial diaphysis and distal epiphysis of the right humerus, a damaged left radius, a portion of the right radial diaphysis, a damaged left ulna, and a portion of the diaphysis of the right ulna. radiographic analysis was unavailable. the portion of the skeleton in greatest abundance, and with the best preservation, is the dentition. both permanent and deciduous teeth are present (tables 1 and 2). the taphonomy is substantial and underscores the paucity of information concerning certain skeletal elements that are present, with destruction to several surfaces in some cases, and the adherence of bone fragments and soil on others. this pattern is found in all available elements, including the roots and crowns of teeth. the skull has postmortem plastic distortion, with a slow crushing effect having taken place over the millennia. the practice of burying individuals on their sides resulted in severe damage to crania and innominates in this skeletal series. in b10-i11, the result is identifiable vault and lateral bones, with a complete loss of identifiable elements in the face, particularly around the nasal aperture. in addition, high clay and sand content caused the burial fill to behave almost like cement, with table 1. inventory of deciduous dentition by root and crown development1 arcade dm2 dm1 dc di2 di1 right side upper pun pun pb pun ac lower pun ac pun ac pun left side upper pun pun pun pun ac lower pun ac pun pun 1pun stands for present but unobservable; pb stands for present but broken; ac stands for apex complete. dental defects at yuguë, mexico 78 fig. 13. distal view, showing the interrupted circumferential plane-like defect on the permanent left maxillary first molar. fig. 14. view of the postmortem breakage that enabled observation of the unerupted dentition for use in dental aging of the specimen. the body was positioned on its left side. this seems to be an extended burial, but the remains of the pelvis and legs are lost. a thick crust adhering to the surface of many bones, obliterating any surface changes, and adding to further deterioration of small bones. the material with the best preservation in this collection is the teeth, having gained some protection within the mandible. the taphonomic damage did facilitate determination of the specimen’s age: the fragmentary condition of the alveolar bone and loose teeth allowed for the observation of crown and root development of erupting and un-erupted dentition (figs. 15-18). this was useful given that radiographic analysis of the skeleton was not possible. burial 10 individual 11 represents the remains of a child, age 5-6 years at the time of death, with severe physiological stress markings on his or her dentition. many of the pathological changes in the teeth mirror those observed in documented cases of congenital syphilis (figs. 1-13). table 2. inventory of permanent dentition by root and crown development* arcade m3 m2 m1 p2 p1 c i2 i1 right side upper r1/2 crc crc r1/4 lower r3.4 ccr r1/4 left side upper cr3/4 pun pun crc ri r1/4 lower pun pun pun *pun stands for present but unobservable, cr3/4 stands for crown ¾ complete, crc stands for crown complete, ri stands for initial root formation, r1/4 root stands for root ¼ complete. a.t. mayes et al. 79 fig. 15. b10-i11, view of the distal aspect of the maxillary right quadrant. the postmortem breakage of the alveolus exposes the second premolar so it can be used for dental aging. fig. 16. b10-i11, left lateral view of skull showing taphonomic changes. fig. 17. b10-i11, right lateral view of skull showing taphonomic changes. deciduous dentition the deciduous dentition of this individual is essentially complete, with 19 of the 20 teeth present. there is extensive lytic invasion of the teeth from dental caries. three out of the seven carious lesions caused decay of over half the tooth surface (urdc, urdi1, uldm1), and one of these resulted in destruction of the crown (urdc). the other four lesions are not as severe, contributing to less than half of the affected surfaces destroyed (urdm2, urdm1, urdi2, lrdm2). caries are primarily located on the interproximal surfaces, as well as one on the labial surface. the labial surfaces of the maxillary lateral incisors each have what can be described as wider-thana-pit hypoplastic defect. on these teeth, the enamel appears to have an eroded or patchy appearance, with dark staining around the margins of the defect. closer examination using magnification revealed abnormal enamel formation, not labial wear or taphonomic change (fig. 19). permanent dentition the developing permanent dentition exhibits extensive pathology which, unlike the deciduous teeth, is not generalized in nature. there are severe hypoplastic patches, or furrows, present on the labial surfaces of the upper right incisor and both lower central incisors. the defects are approximately 2 mm by 1 mm on average (figs. 1, 20, 21). these defects are irregular. the central maxillary incisor is affected starting from the incisal edge, making the individual around one year old at the time of biological stress (reid and dean, 2006), followed by a slight recovery at one point, and then continuing dental defects at yuguë, mexico 80 until approximately two years old. the defect on the right mandibular central incisor began at around one year of age, with normal enamel formation resuming approximately 6 months later (using reid and dean, 2006). the maxillary incisors are symmetrical relevant to being developmentally affected, with the right incisor having two hypoplastic patches and a planelike hypoplastic defect giving a cinched appearance, and the left having an unusual heart-shaped form that is an exaggeration of the normal scalloped shape (see figs. 1-3). the left maxillary canine has a plane-like hypoplastic defect circumferentially near the occlusal surface, giving the cusp both a reduced and very pointed appearance (occurring between 1.4-2.0 years of age). this fang-like morphology is described in jacobi et al. (1992) as resulting from cuspal hypoplastic lesions, and often present in cases of congenital syphilis (fig. 6). all four permanent first molars are present, and all exhibit a similar defect in form (figs. 9-13). the occlusal third of the crown is reduced circumferentially from the rest. the base of the crown is wider than coronally, as the occlusal surface is markedly undersize. the difference between this section and the remainder of the crown creates a distinct ridge, which can also be described as a plane-like hypoplastic defect. the occlusal surface appears as a mass of randomly placed globules rather than defined cusps (figs. 7-8). there is no defect apparent between the plane-like developmental defect and the cemento-enamel junction, indicating that the severe stress occurred very early in life and affected cusp formation from its inception, with relief at around one to one-and-a-half years. in comparison to the permanent second molar, the first molars are reduced in overall size, an additional symptom of the disease (mansilla and pijoan, 1995). all of these features are present in descriptions of congenital syphilis (steinbock, 1976; hillson et al., 1998). discussion given the ongoing debate concerning the origins and antiquity of syphilis, it is important to rule out what the changes in the dentition do not reflect. there are several reasons why the dental defects described here are best interpreted as evidence for congenital syphilis rather than other forms of treponematosis. congenital yaws, for instance, has been suggested as a cause of syphilislike symptoms (ortner, 2003). however, dental stigmata described here require the mother to be in the secondary stage of the disease when pregnant, whereas other forms of treponematosis (like yaws) do not produce symptoms until after birth. in terms of other diseases and stresses, children with congenital tuberculosis die shortly after birth (lewis, 2007), leaving no time for developmental changes to the permanent dentition. a deficiency in vitamin c (scurvy) affects the dentition indirectly, and then only the roots (lewis, 2007). with regard to non-specific indicators of stress, such as hypoplastic defects, it is clear that a host of diseases can and do cause disruptions and changes in dental formation, but, in these cases, all teeth can be affected. in the case of b10-i11, very specific teeth were malformed at very specific points during development. as mentioned, a review of the literature on congenital syphilis suggests two levels of patterning in dental defects. level i defects are genetically tied to the age of development for the involved dentition, and the range of affected teeth within a dental field is restricted to the first incisor, the canine, and the first molar. level ii defects refer to differences in the range of form of the affected teeth, and their variation in environmental expression or host response (which may encompass a differential population response). this range in acquired defects may be particularly important in discerning differences between old world and new world manifestations of congenital syphilis, or as evidence of multiple syndromes. it should be noted that skeletal manifestations of treponematosis also vary in form and severity. while skeletal changes due to treponematosis have been documented in similar regions of the anatomy or skeletal elements, the degree of involvement differs with each syndrome (steinbock, 1976). it cannot be ruled out that slight variations in affected dentition may occur as well. for instance, hutchinson and richman (2006) discuss permanent first molars from two separate suspected syphilitic new world individuals. “however, neither could be defined as a good example of a moon’s molar” (hutchinson and richman, 2006:551). it should be noted, however, that their description of this tooth, and others, fit the level i rules of affected teeth; the tooth they present (their fig. 11:555) does have a severe plane-like defect, with a reduction of cusp size from the occlusal tip. the tooth appears to be a slight variation in form of previously described moon’s molars. the literature varies as to the frequency of dental stigmata in cases of congenital syphilis. the range of 30-45% (erdal, 2006; steinbock 1976; hillson et al., 1998) can be attributed to discussions on specific characteristics in documented cases and archaeological collections. while these frequencies differ, several points are clear. first, dental stigmata are not exhibited 100% of the time, even in documented historic cases. using putkonen’s figures of hutchinson’s incisors being present in 45% of the cases of congenital syphilis, then it should be equally clear that in 55% of the cases, they are not. another facet of the disease is that individuals may not exhibit any of the dental defects, and only show changes in the cranial and post-cranial bones. when dental defects do exist, depending on when the affected individual died, there is a range of anomalies that do follow a particular pattern. variation in the morphology of the teeth may be one of the discerning differences between old world and new world a.t. mayes et al. 81 congenital syphilis. the main identifying feature of mulberry, or bud, molars is a “marked defect of enamel hypoplasia, running around the base of all cusps. it corresponds to what has been described as a plane-form hypoplastic defect” (hillson et al., 1998:30). where the cusps of affected teeth are deformed, having “several small knobs representing atrophic cusps” (steinbock 1976: 108). in addition to hutchinson’s incisors, both moon’s and mulberry molars are expressions of congenital syphilis. there are a number of similarities between the teeth from the current study, and that of hillson and colleagues (1998). of note are the narrowed occlusal surface, the disorganization of the cusps, and the plane-like hypoplastic defect visible around the circumference. any combination of these dental defects can be considered expressions of the disease, which is why the degree of certainty in diagnosing congenital syphilis in archaeological specimens can be low, at times. additionally, the degree to which an individual was affected by the disease, and the observed physical changes present at the time of death, may also affect diagnosis of archaeological specimens. fig. 18. b10-i11, right lateral view of skull showing taphonomic changes. fig. 19. b10-i11, labial view of the maxillary left lateral incisor with defective enamel in the middle third of the crown. the canine (on the right in the photograph) shows scattered enamel pitting. manifestations. therefore, knowing and recognizing variation in symptomology of this disease in antiquity can be valuable. it may also be one of the keys to understanding and identifying various forms of this disease and its dispersion globally. hutchinson’s incisors affect the permanent teeth, and the feature is primarily seen in the maxillary central and, occasionally, the mandibular incisors. steinbock notes a wide range of expression in this trait, from the variation described above to “only a depression on the anterior surface of the tooth immediately above the cutting edge, and in some both of these alterations are present” (1976:108). he also notes that it is not always bilateral, and that, in some cases, it may not exist at all. hutchinson and richman (2006) describe a child with “malformed enamel sleeves,” which they note do not look like hutchinson’s incisors as typically described. however, these two teeth do look very similar to those described by steinbock (1976). the right central incisor of b10-i11 also has a malformation that is similar in form. in steinbock’s (1976) examples of dental stigmata for congenital syphilis, the lateral maxillary incisors also are affected. this “notch in the incisal margin and rounding of the incisal angle” with a “fissured” labial surface (see fig. 40 in steinbock 1976:107) describes, and resembles, the permanent left central maxillary incisor of b10-i11 (figs. 1-3). permanent canines exhibit occlusal hypoplastic defects (jacobi et al., 1992), and the first permanent molars are also affected by congenital syphilis. a degree of overall consistency is maintained that aids in identification in expected dental stigmata. descriptive summaries of the defects are also useful in comparing data. jacobi and colleagues (1992) provide a summary table of descriptions of characteristics attributed to dental defects at yuguë, mexico 82 skeletal investigations of pre-contact burials from gabriola island, canada (pacific northwest) identified several individuals, adult and sub-adult, with skeletal changes that appear to be due to syphilis. curtin (2005) describes a disassociated juvenile mandible, the teeth of whom match the current description of syphilitic stigmata, and which parallel case study (b10-i11) presented here, both in terms of the teeth affected and the degree of malformation. the affected teeth are the two permanent mandibular first molars and the developing right permanent mandibular canine. the molars are severely hypoplastic, with rounded bulbous cusp tips constricted at their base by a deep, irregularly pitted hypoplastic groove that encircles the crown. the cusp tips appear crowded together toward the center of the occlusal surface, which itself features many small, irregular enamel globules, producing the ‘mulberry’ appearance characteristic of fournier molars [curtin, 2005:315]. additionally, the canines are described as having “circumferential” and “furrow-shaped defects “remarkably similar to one illustrated in hutchinson’s 1887 treatise on syphilis” (curtin, 2005:315). the described pattern of the canine is a slight variation from hillson and colleagues’ (1998) descriptions, but it mirrors that of b10-i11. similarly, the authors note that the gabriola island individual has a deciduous dentition with marked hypoplastic defects. in a skeletal collection from barbados, jacobi and colleagues (1992) have described the impact that congenital syphilis had on nineteenth century africanamerican slaves. three individuals, all adolescents or young adults, had hutchinson’s incisors and moon’s molars. the authors acknowledge that many of the children who died from the disease might not have developed the characteristic dental deformations. they assert that the infant mortality rate due to congenital syphilis was probably quite a bit higher than evidenced by the skeletons themselves. not all infected infants will acquire the dental stigmata, but most will have changes in some skeletal units. those who survived to childhood would recover, leaving little evidence of these changes to their long bones during infancy (steinbock, 1976). this is important, for even if the lower limbs of individual b10-i11 had not been missing, given the age of the individual at death and depending on the severity of the infection, no pathological change may have been evident. hillson and colleagues (1998) do not consider the deciduous dentition to be a part of the normal stigmata, but other sources have noted severe developmental disruptions of the milk teeth (steinbock, 1976; ortner, 2003; curtin, 2005; hutchinson and richman, 2006). defects on the deciduous dentition, while not normally considered part of the suite of changes, certainly speak fig. 20. deciduous left maxillary lateral incisor with a lingual hypoplastic defect in the middle third of the crown. fig. 21. permanent mandibular central incisors with furrowed defect in the middle third of the crown; labial view. distal is to the left of the photograph; scale in millimeters. a.t. mayes et al. 83 to issues with the mother’s health during fetal development. given that congenital syphilis is contracted transplacentally (lewis, 2007), it is expected that other negative effects on the growing fetus can be documented, so the hypoplastic “patch” identified on the central maxillary deciduous incisor of b10-i11, and additional hypoplastic pitting, are not surprising. conclusion differential diagnosis of congenital syphilis from skeletal remains should consider all bony and dental manifestations. the postmortem damage to this individual is considerable, with the face splintered, the skull crushed, and the lower extremities absent. preservation and taphonomy prevented the assessment of the skeletal markers of congenital syphilis in this case. however, the pattern of dental defects that developed is significant and is consistent with previously described changes due to congenital syphilis. not every manifestation of treponematosis is completely understood. it is for this reason that all possible cases should be introduced, particularly when what is observed follows a generally recognizable pattern, though with slight morphological variation. such variations are already documented in the literature (hillson et al. 1998), meaning that case studies, even from unexpected locales, cannot be ignored. possibly, expression of some malformations varies by population (genetic and physiological) and/or the environmental framework, but which teeth are affected by this disease process, does not vary. if there are evolutionary differences in form for this disease based on geographic location, or on differing bacteria, they do not appear to affect the level i rules of dental field pattern. there are, nonetheless, certain variations of level ii-expression of malformations. a better understanding of these differences and their range of expression may aid in identifying new world and old world syndromes in antiquity. the data presented here is suggestive of a congenital form of treponematosis in the new world, possibly congenital syphilis. acknowledgments we would like to thank the instituto nacional de antroplogía e historia for sanctioning the skeletal analysis on which this paper is based. we are particularly indebted to the president and members of the consejo de arqueología, the directors of the centro inah-oaxaca, including eduardo lópez calzada, and doctor sergio lópez alonso. we would also like to thank angela berg collins for photographic archiving the dentition presented here, and field assistant josé aguilar. funding for the osteological field research was provided by grants from the college of arts and letters, and a research, scholarship, and creative activity grant (rsca), san diego state university. literature cited baker, bj, dupras tl, tocheri mw. 2005. the osteology of infants and children. college station, texas a&m press. barber sb. 2005. heterogeneity, identity, and complexity: negotiating status and authority in terminal formative coastal oaxaca. ph.d. dissertation, university of colorado, boulder. centurion-lara a, castro c, castillo r, shaffer jm, van voorhis wc, lukehart sa. 1998. the flanking region sequences of the 15-kda lipoprotein gene differentiate pathogenic treponemes. j 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powell ml. and cook dc, editors. the myth of syphilis: the natural history of treponematosis in north america. gainesville: university of florida press. p 1-8. reid dj. 2006. variation in modern human enamel formation times. hum evol 50:329-346. rothschild bm. 2005. history of syphilis. clin infect dis 40:1454-1463. santos rv, coimbra cea. 1999. hardships of contact: enamel hypoplasias in tupí-mondé amerindians from the brazilian amazonia. am j phys anthropol 109:111-127. steinbock rt. 1976. paleopathological diagnosis and interpretation: bone diseases in ancient human populations.springfield, illinois: charles c. thomas. harris and corruccini 2008.1 1 dental “occlusion” refers to how well the teeth are arranged individually and one-to-another within and between the dental arches. grainger (1967) suggests that, “malocclusion is any disharmonious variation from the accepted or theoretical normal arrangements of the teeth. but, in nature some degree of variation among individuals of a species is always present.” proper (ideal) occlusion provides several benefits over maloccluded teeth. perhaps foremost in contemporary western society, proper occlusion carries an esthetic benefit. people with good occlusion are rated as more attractive, more intelligent, and more desirable employees and spouses than people with malocclusions (shaw et al., 1979; shaw, 1981; shaw et al., 1985; birkeland et al., 2000; cerny, 2005; traebert and peres, 2007). proper occlusion involves more tooth-to-tooth contacts, which produces more complete trituration of food (owens et al., 2002). it is easier to maintain oral health around properly aligned teeth, so health of the periodontium tends to be better and tooth decay may be lessened (e.g., sergio and hawley, 1999; kao et al., 2000; klages et al., 2007). above all, a toothy smile is highly sought after in the modern western world. morrey and nelsen (1972:190-198) depict orthodontic interventions. good articulation and phonation should also be mentioned here, since making certain sounds depends on correct tongue-to-tooth relationships (e.g., van norman, 1997; mohlin and kurol, 2003). there has been discussion, for example, about the origin of the consonant “f” and how agriculturally (hence, recently) it arose due to maxillary incisor overjet (corruccini 1987). “malocclusion” is a common term, but it has a couple of shortcomings. there is no clear demarcation between a good or adequate occlusion and malocclusion; any distinction is one of degree rather than kind. more importantly, virtually everyone has some sort of “malocclusion,” so it is misleading to talk about normal or proper occlusion when we actually mean idealized, perfect occlusion. “occlusal variation” is a more appropriate, neutral term to refer to the positional variations of teeth and tooth relationships that are found in most people in the absence of orthodontic treatment. lombardi and bailit (1972:283) offer a moreinvolved description: the term “malocclusion,” encompassing all deviations of the teeth and jaws from normal alignment, includes a number of distinct conditions which may or may not be independent: malpositioning of individual teeth (rotation, tipping, overand undereruption); discrepancies between tooth and jaw size (crowding and spacing); and malrelations of the dental arches (sagittal, transverse and vertical). dental arch malrelations may reflect abnormalities in the dentition, the jaws, or both. a fundamental dichotomy can be drawn as to the sources of malocclusion, and these two sources can be labeled bone-based and tooth-based (e.g., harris and johnson, 1991; harris, 2008). that is, one way of developing improper occlusion is for the supporting bones of the two jaws to grow “inappropriately.” if, for example, the mandible grows forward much more quantification of dental occlusal variation: a review of methods edward f. harris1* and robert s. corruccini2 1department of orthodontics, university of tennessee, memphis, tennessee 2department of anthropology, southern illinois university, carbondale, illinois abstract occlusion—how the teeth fit together within and between the arches—has important consequences functionally and especially esthetically. occlusal variation is considerable in modern westernized societies, but the occurrence and extent of the variation appear to be lower in the past and lower in non-westernized groups. this methodological paper describes several commonly-used variables that, collectively, characterize occlusal variation. methods are described from the literature that measure the location and extent of tooth relations in all three planes of space. our goal is that, by describing methods in a single source, it will pique the interest of dental researchers to collect these data, so that the space-time distributions of occlusal variations can be known in more detail. dental anthropology 2008;21(1):1-11. correspondence to: edward harris, department of orthodontics, 870 union avenue, university of tennessee, memphis, tennessee 38163. e-mail: eharris@utmem.edu 2 than the maxilla, the teeth supported by these bony elements will not properly interdigitate. comparably, if the palatal plane of the midface is canted up in the front, the anterior teeth cannot couple between the jaws resulting in an anterior openbite. bone-based malrelationships can occur in any combination of the three planes of space (e.g., moyers, 1988; proffit, 2007), and, given the familial resemblances in the sizes and shapes of the facial bones (e.g., nakata et al., 1974a,b; harris, 1975), these “bone-based” causes of malocclusion tend to be under genetic control. distinct from this are the familiar “crooked teeth,” where it is the actual positions of teeth in the alveolar bone that create esthetic and functional problems. these “tooth-based” issues involve the locations, rotations, and angulations of teeth unto themselves as well as one to another. these tooth-based variables appear to be under little genetic control and, conversely, seem to be a consequence of the environment (corruccini and potter, 1980; harris and smith, 1980). this dichotomy between boneand tooth-based causes of malocclusion is not absolute; problems with the sizes of the supporting jaws can preclude proper interdigitation of the teeth—leading to tooth-based occlusal issues. still, we contend that much of the conflict in the literature about the etiology of malocclusion stems from uncritical lumping of boneand tooth-based kinds of malocclusion. the present paper focuses primarily on recording these latter, tooth-based sorts of malocclusion, and these are variables readily measured from inspection of the dental arches (or dental casts) themselves rather than the skeletodental facial complexes (e.g., athanasiou, 1995). the purpose of the present paper is to describe some of the methods used by orthodontists and epidemiologists to quantify the extent of a person’s occlusal variation. these dimensions are chosen because they can be made with sliding calipers (or a ruler) rather than more complex instrumentation, so the data are at least interval scale (ellis, 1966) but are fairly simple to collect. several dimensions can be measured in vivo, but it is much easier on the subject and more consistent and accurate to collect the data from skulls or full-mouth dental casts. the variables can be compounded into a variety of indices expressing overall deviation from the ideal; kelly and harvey (1977:appendix i) present particularly useful details for scoring the “treatment priority index.” our intent is that, by describing these variables, more dental researchers will collect data on malocclusion, providing a richer store of information about the advent, extent, and sorts of malocclusion through human history. centric relation and centric occlusion dentists recognize two dental relationships, termed centric relation (cr) and centric occlusion (co). cr is a stable, reproducible position, where the condyles are seated in their superior-most and rear-most positions in the glenoid fossae (ramfjord and ash, 1971). there are, however, mixed views concerning the “best” condylefossa relationship for cr (e.g., davies et al., 2001). the concept of cr is founded in prosthodontic aspects of dentistry, notably when the patient is edentulous and the dentist requires a reproducible reference position for building a denture. cr also is encountered in research by gnathologists, where the focus often is on rehabilitating a person’s dentition to relieve bruxism, temporomandibular dysfunctions, myofacial pain, or other problems. cr can only be determined in living persons; it cannot be determined from dental casts or with skeletal material (because the meniscus and cartilaginous joint linings are absent). centric occlusion (co), in contrast, is a person’s habitual bite, and this is the same as maximum intercuspation. co can generally be determined from casts alone, though the casts may fit together in various ways if the occlusion is particularly poor. it is of little consequence when measuring occlusal variation, but cr and co often do not coincide. there often is a “slide” from cr forward to co, but details are beyond this overview (ramfjord and ash, 1971). the convention throughout the present review is to place the teeth (or casts) in maximum interdigitation or, synonymously, habitual bite. incisor overbite and overjet the incisal edge of the lower central incisor should be quite close to the lingual contour of the upper incisor when the dentition is in maximum intercuspation. this can be measured vertically (overbite) and horizontally (overjet). incisor overbite is the vertical (craniocaudal, occlusogingival) distance between the incisal edges of the central incisors (fig. 1a) measured perpendicular to the occlusal plane. the easiest way to measure this (baume et al., 1973) is (1) to place the casts in maximum intercuspation, (2) use a fine lead pencil to mark where the incisal edge of the upper incisor occludes over the lower incisor, (3) separate the casts, and (4) use the depth gauge of the calipers to measure how far the pencil mark is from the incisal edge of the lower incisor. one convention is to measure either the left or right central incisors with the greater overbite; others (e.g., smith and bailit, 1977) measure both sides and record the average. when the incisors do not meet and there is an anterior openbite (also termed negative overbite and apertognathia), the gap between the incisor edges in the two jaws is measured perpendicular to the occlusal plane, and the value is recorded as a negative value. overbite will be underestimated if the incisors are incompletely erupted and also if there is occlusal attrition that has worn down the crown heights. indeed, considerable attrition—as is common with abrasive e.f. harris and r.s. corruccini � diets—will cause the loss of tooth substance to the point that the mandible autorotates into an edge-toedge incisal bite. brace (1977) argues this edge-to-edge bite is actually the preindustrial norm. overjet refers to the horizontal (dorsoventral or labiolingual) distance between the facial tangents of the central incisors in the two arcades (fig. 1b). with the casts interdigitated, the depth gauge of sliding calipers can be used to measure the distance from the labial surface of the more prominent maxillary central incisor distally to the face of the mandibular antagonist. if the mandible is very prominent or the maxilla is undersize (or both), the mandibular incisors can be in front of (labial to) the upper incisors (i.e., anterior crossbite). this “underbite” is measured in the same manner as overbite, but the distance is recorded as negative. this occasional situation is variously labeled underjet, negative overjet, reverse overjet, anterior crossbite and mandibular overjet with the last two being most commonly encountered (grainger, 1967). buccal segment relationship how the molars, particularly the first molar in each arch, fit together in the mesiodistal (parasagittal) plane depends on several factors, including how the teeth are positioned on the supporting basal bone of each arch, but also on the sizes of the upper and lower jaws. “proper” occlusion occurs when the mesiobuccal cusp of the maxillary first molar is positioned parasagittally in the buccal groove of the mandibular fig. 1. lateral view of the central incisors, showing (a) the method of measuring overbite, measured normal to downs’ occlusal plane and (b) overjet measured parallel with downs’ occlusal plane. incisors with no vertical overlap have a negative overbite (openbite). incisors in anterior crossbite have a negative value for overjet. conventionally, the quadrant with the greater deviation is recorded. ba quantifying occlusal variation fig. 2. these buccal views of the permanent first molars depict edward h. angle’s time-honored three classes of molar relationship. left: a full-cusp class iii (mesioclusion) relationship occurs when the maxillary tooth is too distal or, more commonly, the mandibular tooth is too mesial. center: the desired molar relationship (neutroclusion) has the mesiobuccal cusp of the upper molar aligned in the buccal groove of the lower molar. right: a full-step class ii relationship (distoclusion) is shown, commonly (but not necessarily) due to insufficient horizontal growth of the mandible. it is not necessary to have such extreme (full-cusp) discrepancies to achieve angle’s class ii or iii relationships. mesialdistal fig. 3. buccal segment relationship (bsr) is measured on an interval-scale as the distance (parallel with the occlusal plane) between the mesiobuccal cusp of the upper molar and the buccal groove of the mandibular molar. by convention, the distance is positive in cases of mesioclusion (class iii), negative with distoclusion (class ii), and zero with neutroclusion (class i). an example of distoclusion is illustrated. 4 first molar. this is the angle class i relation commonly evaluated by orthodontists (fig. 2). this classification was developed by edward h. angle, a historically prominent orthodontist in the late 18th century (e.g., angle, 1899). consequently, no “angle” is involved in this categorization of molar relationships. angle’s molar classification can be described more accurately using a continuous scheme that is termed buccal fig. 4. the mesiodistal crown dimensions of all of these teeth are drawn to the same scale, showing that when a class i bsr occurs at the first molars, there is a better chance that all of the teeth will be properly aligned within each arch and properly interdigitate between the arches. fig. 5. lateral view of the canines, showing the method of measuring canine discrepancy, which is the horizontal deviation of the maxillary canine’s cusp tip relative to the mandibular canine-first premolar embrasure. the horizontal discrepancy is measured with sliding calipers. if, as diagrammed here, the mandibular canine-premolar embrasure is distal of its ideal position (class ii), the distance is labeled negative. fig. 6. diagram of the labial view of the incisors, showing the method of measuring the deviation of the maxillary and mandibular dental midlines. if the midlines are coincident, the discrepancy is zero. the horizontal discrepancy can be measured with sliding calipers. mandibular shifts to the right are labeled positive (harris and bodford, 2007). e.f. harris and r.s. corruccini 5 segment relationship (bsr; fig. 3). given characteristic mesiodistal crown size relationships for a person’s teeth, a class i molar relationship goes far towards assuring that all of the teeth mesial to the permanent first molars will interdigitate properly between the two arches (fig. 4). angle’s three-grade classification is a valuable descriptive method, but recording bsr on a continuous scale (fig. 3) is more informative for most research efforts. when the mesiobucal cusp (paracone) is “socked into” (symmetrically overlaps) the buccal groove, bsr is zero. this corresponds to ideal occlusion of the protocone in the mandibular antagonist’s central occlusal fovea and of the hypoconid in the maxillary antagonist’s central occlusal fovea (see hillson 1996:chapter 4). the value is negative when the lower molar groove is distal of the upper molar ’s cusp (distoclusion); the value is positive when the groove is mesial to the upper molar ’s cusp tip (mesioclusion). left-right asymmetries are common, so it can be useful to score bsr on both sides of the arch (siegel, 2002). in practice, the buccal groove extends fairly far down the molar ’s crown, so it is identifiable with moderate occlusal attrition. the cusp tip can be extrapolated from the wear facet if the upper molar is not severely worn. canine relationship analogous with bsr, the parasagittal position of the cusp tip of the maxillary canine can be measured relative to the canine-first premolar embrasure in the mandible. with ideal interdigitation, the canine’s cusp tip should fit into this embrasure (fig. 5). when the canine is distal of the embrasure, the distance is recorded as negative; otherwise positive (harris and bodford, 2007). midline deviation the dental midlines of the two jaws should be coincident, and, in the living, the dental midline (at the embrasure of the central incisors) also should be coincident with the frenulum in the superior labial vestibule. midline deviations indicate left-right arch asymmetries. by convention (harris and bodford, 2007), when the mandibular dental midline deviates to the right of the maxillary midline, the distance (measured with calipers) is labeled positive; otherwise negative (fig. 6). when the dental midlines are coincident, the “deviation” is zero. midline diastema a diastema is a space between teeth, such as occurs between tooth types in many species. in dentistry, a diastema refers specifically to a space or gap between the maxillary central incisors (fig. 7). a diastema— defined as a space at least 2 mm wide—was recorded as part of the u.s. national health examination survey (nhanes iii; nchs, 1994). care has to be taken in contemporary groups that the diastema was not closed orthodontically or restoratively (with, e.g., crowns or composite). the frequency is about 6% in american whites, but twice that in african americans (brunelle et al., 1996). figure 7 shows how the width of the diastema is measured millimetrically. it also is important to distinguish between a midline space created by axial deviations of the central incisors that separates these teeth labiolingually versus a true diastema of a mediolateral separation of the incisors’ locations in the supporting alveolar bone. beware also of incisor fig. 8. facial views of the first molars showing transverse relationships: (a) buccal crossbite; (b) normal mediolateral relationship, with the upper buccal cusp overhanging the mandibular cusp and the upper lingual cusp occluding in the lower molar’s central fovea, and (c) lingual crossbite. fig. 7. a diastema occasionally occurs between the maxillary central incisors, often due to a fibrous band of gingival tissue that keeps the teeth apart. width of the diastema is measured, as shown, between the medial anatomic contact points of the central incisors parallel with the occlusal plane. quantifying occlusal variation � “winging,” which may be genetic and unrelated to occlusal variation (cf. enoki and dahlberg, 1958). interdental spacing in the anterior region is much more common in the deciduous dentition, but the larger permanent successors generally use up the space. some people with a diastema have a fibrous band of gingival tissue that maintains the space. posterior crossbite normally the buccal cusps of the teeth in the maxillary buccal segment (the premolars and molars) should extend laterally and overhang the buccal cusps of the lower “contained” arch (wheeler, 1965; ramfjord and ash, 1971). a posterior buccal crossbite occurs when the maxillary teeth extend too far laterally compared to the mandibular antagonists. conversely, and more commonly, posterior lingual crossbites occur when the maxillary buccal cusps occlude too lingually. several methods of scoring crossbites have been suggested. baume et al. (1973) propose a simple threegrade ordinal classification of posterior crossbites (fig. 8). this diagram illustrates full-cusp crossbites (either buccal or lingual), but cases do not have to be this extreme to be counted. grainger (1967) and kelly and harvey (1977) simply count the number of teeth in the premolar-molar arch segments that are buccally or lingually displaced out of the projected arch form, giving special emphasis to deviations of “cusp to cusp” or worse (e.g., paracone apex occludes on the lingual aspect of the protoconid and hypoconid). smith and bailit (1977) suggest that the occurrences of lingual and buccal crossbites should be recorded separately. tooth rotations a tooth can be located in its ideal position in the dental arch, but rotated around its long axis. the degrees of rotation can be measured (as with a protractor), but most epidemiological studies have opted to use an ordinal scoring scheme (fig. 9). an unrotated tooth has a rotation score of zero, while rotations can be “minor” or “major.” a minor rotation is defined as less that 45º and is given a score of 1. a major rotation is > 45º relative to the arch form and is given a score of 2. rotation score is the sum for the whole mouth (optionally excluding third molars). in other words, a person’s rotation score is the number of teeth with minor rotations plus twice the number of teeth with major rotations (grainger, 1967; kelly and harvey, 1977). tooth displacements teeth can be ectopically positioned out of alignment (fig. 10). that is, the tooth is effectively in its idealized axial inclination (not tipped) and in its idealized position rotationally, but it is displaced out of the arch form. van vark and pennell (1959) developed an ordinal scale for quantifying tooth displacements. if, visually, a tooth is in its idealized position in the dental arch, its score is zero. if, instead, the tooth is slightly displaced—up to 2 mm—its displacement score is 1. if the displacement is > 2 mm, its score is 2. the displacement score for the whole mouth (presumably 28 teeth) is the sum of the scores. grainger (1967), kelly and harvey (1977), fig. 9. tooth rotations are scored as (a) the number of teeth rotated less than 45° relative to the idealized arch form plus (b) twice the number of teeth rotated 45° or more. teeth throughout the dentition are scored. this example shows the rotation of the lower right central incisor of less than 45° relative to the arch form. fig. 10. tooth displacements are scored as (a) the number of teeth displaced out of the idealized arch form plus (b) twice the number of teeth displaced more than 2 mm out of the arch form. teeth throughout the dentition are scored. this example shows a labial displacement of more than 2 mm of the mandibular lateral incisor. incisor irregularity: a + b + c + d + e a b c d e fig. 11. incisor irregularity is the millimetric sum of the five anatomic contacts among the six anterior teeth. the maxillary is shown here, though little (1976) devised the index for measuring crowding in the mandible. when all five contacts are approximated, the index is zero. e.f. harris and r.s. corruccini 7 and smith and bailit (1977) promote this same scoring method. incisor irregularity the most common sort of malocclusion in contemporary westernized populations is incisor crowding (e.g., brunelle et al., 1996), where there is inadequate supporting arch space for proper alignment of the anterior teeth in one or both arches. nowadays, the most broadly applied method of quantifying anterior crowding is little’s incisor irregularity (little, 1975). this method was developed for the mandibular arch, but it is equally applicable to the maxillary arcade. as illustrated in figure 11, there are five interdental contacts between the four incisors plus the adjacent canines in an arcade. in proper occlusion, the anatomic contacts of the adjacent incisors and canines should be closed—so the anatomic contacts of adjacent teeth are together. the greater the dental crowding—reflected as rotations, displacements, and altered axial inclinations of the teeth—the greater the summed distances across the five contacts. the millimetric distances between all open contacts between incisors and canines are measured parallel with the occlusal plane, and the sum is the incisor irregularity. incisor irregularity can range from zero (when all of the contacts are approximated) to some ill-defined upper limit of “crooked” teeth. while quite practical, there are at least two shortcomings of incisor irregularity. one, the sum is insensitive to “accordioned” teeth, where the teeth themselves are rotated about their long axes, but reciprocally, so the anatomic contacts remain close together. secondly, incisor irregularity is insensitive to interdental spacing. in our experience (e.g., turner, 2007), it is best to score cases exhibiting interdental spacing—where the open contacts are due to excess arch space for the given tooth widths—as a separate category of malocclusion. epidemiological studies (e.g., grainger, 1967; baume et al., 1973; jenny and cons, 1996) suggest scoring (measuring) just the most deviant tooth, but their emphasis is on facial esthetics and on abbreviating data collection. in our experience, using just the extreme deviation as a proxy for irregularity throughout the anterior segments is coarse and precludes much analysis (harris et al., 1987). experience suggests that incisor irregularity is a much more comprehensive measure of dental irregularity. arch depth arch depth (e.g., harris, 1997) is the mesiodistal distance from the labial surface of the central incisors back to the distal margins of the first molar (fig. 12) along the midline. the anatomic midline of the palate is evident as the midline raphe in the maxilla (or the intermaxillary suture in skeletal material). the midline needs to be estimated in the mandible. various authors (e.g., mills, 1964) label this dimension arch length. knott (1961), dekock (1972), and others have employed geometry to determine arch depth as the formula for the median of a triangle with known sides. using the dental landmarks of a, b, and c in figure 13, arch depth d is calculated from the formula fig. 12. diagrammatic illustration of maxillary arch depth. depth can be measured independently on the maxillary and mandibular arches. operationally, a straight-edge is positioned against the distal heels of the permanent first molars (so there may be some dentoalveolar asymmetry) and the depth is measured from the labial of the central incisors, along the median raphe, to the back of the first molars. a b c d fig. 13. once the arch chords ac and bc and arch width ab are known, arch depth (d) can be calculated as the median height of the triangle (see text). quantifying occlusal variation 8 d = ac2 + bc2 2 ab2 4 arch chords measures of arch chords (moorrees and reed, 1954; sillman, 1964; knott, 1972) are included here because their measurement in each quadrant can disclose arch asymmetries. cassidy et al. (1988) suggested two chord dimensions, one that they labeled a 1-3 chord. this is from the midline embrasure of the central incisors obliquely to the distal heel of the canine (fig. 14). this would be measured in the corresponding left and right quadrants, and the greater the difference, the greater the bilateral asymmetry. the second chord, labeled the 1-6 chord, is from the same midline embrasure of the central incisors obliquely back to the distobuccal heel of the first molar (fig. 14). likewise, this can be done in both quadrants of both arches. curve of spee the curve of spee is the curve defined by the occlusal surfaces of the mandibular teeth in the occlusogingival plane. this eponym refers to ferdinand graf von spee who described the curve as a segment of a circle. strictly, spee’s curve extends between the canine and the terminal molar. however, the incisors often are included in the measurement (e.g., bernstein et al., 2007). the maximum depth of the curve is measured (fig. 15). a flat object, like a ruler, is laid on the mandibular occlusal surfaces, and the depth of the tooth farthest from this plane—commonly a premolar—is recorded. oftentimes the incisors are super-erupted, so a greater distance (depth of the curve) is obtained than when excluding the incisors. a shallow curve of spee is thought to be an integral part of a sound occlusion. the curve deepens as teeth slip their anatomic contacts occlusogingivally. discussion any number of anatomical, muscular, behavioral, physiological and other factors can divert one or more teeth out of their “proper” occlusal positions. these factors can be in force as the tooth forms in its crypt, during eruption, and/or after occlusion has been established. the topics of how and why malocclusion develops (and progresses with age) are too complex to be dealt with here (e.g., proffit, 1985; harris, 1997; corruccini, 1999). instead, our intent is to review some of the common methods used to quantify the nature and extent of occlusal variation. deviations of tooth positions from the ideal are far more the rule than the exception among current westernized populations. national surveys of u.s. youths suggest that only about 1 teenager in 10 develops naturally-occurring good occlusion, and fully a third of youths develop malocclusions labeled “severe” and “handicapping” (kelly and harvey, 1977; brunelle et al., 1996). consequently, “proper” or idealized occlusion is much less common in the absence of treatment than “normal” or average occlusion. hillson (2005:281-284) argues that occlusal variation is also much higher in domestic than in wild nonhuman animals. with human malocclusions being so common (and probably fig. 14. diagrammatic illustration of a maxillary dental arch, showing the manner that, with sliding calipers, the incisor-to-canine (1-3) and the incisor-tomolar (1-6) arch chords are measured. in practice, both of these chords can be measured on the left and right sides of both the maxillary and mandibular arches. fig. 15. the curve of spee is measured as the maximum distance from a plane defined by the most occlusal anterior and posterior teeth. as diagrammed here, this would be in the region of the second premolar. e.f. harris and r.s. corruccini 9 continuing to rise), it is a valuable research question to ask what sorts of malocclusions occur and their severity. clinically, quantification of the kind and severity of malocclusion is driven by (1) the need to best allocate public funds for treatment of financially disadvantaged citizens, but also (2) to evaluate the difficulty and prognosis of treatment. these efforts are different from the interests of basic scientists who aim to assess the impact of malocclusion on societies, and its population variation through time and space (e.g., corruccini, 1984; brunelle et al., 1996). as we mentioned, the impetus for delineating these measures of occlusal variation is to stimulate interest among dental researchers concerning how these dimensions vary in their own data. it is worth commenting in this vein that several dental considerations can deflect the development of “proper” occlusion. some developmental considerations, such as eruptive pathways (e.g., barberia-leache et al., 2005), patterns of eruption (e.g., tompkins, 1996), and premature loss of primary teeth (e.g., fanning, 1962) are difficult or impossible to reconstruct from subjects evaluated in the full dentition, but other developmental factors are more persistent. data may need to be categorized by age grade, and the variables described here are generally specific to the permanent dentition rather than the mixed dentition because of ongoing changes as the permanent teeth erupt (e.g., baume, 1950; moorrees, 1959). for archeological remains (where age at death has to be estimated), the degree of occlusal wear can be a useful proxy (e.g., smith, 1984) since wear affects occlusal relationships. also, it generally is useful also to collect data on other, abnormal dental conditions that can affect occlusion, notably (1) congenitally absent teeth, (2) supernumerary teeth, (3) abnormal crown size and form (e.g., macrodontia, microdontia), (4) impacted teeth (and retained primary teeth), and (5) transposed teeth (baume et al., 1973). particularly with older subjects, issues of tooth loss due to caries, trauma, and/or periodontal involvement also may impact the occlusal findings because of the life-long effects of the anterior component of force (southard et al., 1989) and the tension of trans-septal fibers (picton and moss, 1973) that shift teeth in areas of interproximal attrition and tooth loss. little is known about the effects of occlusal and interproximal attrition on occlusal variation, but abrasion doubtlessly affects the occlusion of adults living with a lot of grit in their diet (e.g., begg, 1954; sengupta et al., 1999; brook et al., 2006). interproximal attrition reduces the space required for the teeth, and this translates into reduced arch length (e.g., lysell, 1958; fishman, 1973), though not as much as claimed by begg (cf. murphy, 1964; corruccini, 1999). additionally, occlusal attrition reduces crown heights and, consequently, reduces lower face height (fishman, 1973). in turn, reduced crown heights allow the mandible to autorotate forward-and-upward, one consequence being that incisor overjet often is replaced by an edge-to-edge bite with horizontal wear on the incisal contacts (e.g., begg, 1954). a related clinical issue is third molar impaction (mucci 1982), like most occlusal variation a result simply of insufficient alveolar space for proper eruption, but this topic is usually treated differently because it is the province of a different clinical specialty, oral surgery as opposed to orthodontics. in summary, this paper describes methods useful for quantifying the nature and extent of occlusal variation. variations (“malocclusions”) are very common in contemporary humans, but 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