Bioarchaeology International Bioarchaeology International Volume 8, Numbers 1–2: 63–84 DOI: 10.5744/bi.2022.0030 © 2024 University of Florida Press Gender across Generations: Childhood Food Practices as Socialization Processes in Ancient China Melanie J. Miller,a,b,c* Siân E. Halcrow,a Bowen Yang,d Yu Dong,d Kate Pechenkina,e and Wenquan Fanf aDepartment of Anatomy, University of Otago, Dunedin, New Zealand bArchaeological Research Facility, University of California, Berkeley, Berkeley, CA, USA cNorthern California Institute for Research and Education, San Francisco, CA, USA dInstitute of Cultural Heritage, Shandong University, Qingdao, China eDepartment of Anthropology, Queens College, City University of New York, New York, NY, USA fHenan Provincial Institute of Cultural Heritage and Archaeology, Zhengzhou, China *Correspondence to: Melanie J. Miller, Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand E-mail: millermj@berkeley.edu ABSTRACT Food is a biological imperative as well as a core material that humans use in socializing ourselves, and the things we choose to consume are infused with cultural meanings. Children, especially very young children, have little agency in subsistence decisions, and therefore the foods that caretakers feed to children may hold profound information about cultural value systems and reveal social processes and idealized identities. Here we focus on relationships between food, sex, and gender in early life by studying the childhood diets of 57 Eastern Zhou pe- riod individuals from the Central Plains region of China (771– 221 BCE). Using stable isotope analysis of incre- mental dentin samples, we create detailed dietary histories of childhood years. From very early in life, the average δ15N value for boys is notably higher than the average for girls, indicating slightly more protein consumption for most males, and this continues across childhood. Foods such as meat and millet were highly valued in ancient China and, whether intentional or not, become associated with aspects of sex and gender through preferential feeding to male children. These isotopic data reveal a key aspect of the socializing processes of children across generational interactions with caretakers, with food communicating information about social worth and gen- der, which becomes embodied in the developing child. Keywords: stable isotope; childhood; China 摘要：食物是生物生存必需品，也是人类社会化过程中的的重要材料，人们选择消费的食物常常富含文化意 义。儿童，特别是年幼的儿童，不具备自主选择食物的能力，照顾者给儿童的饮食可能包含大量关于社会文 化体系的信息，因此可以揭示当时的社会进程和理想化的身份。在本文中，我们通过研究东周时期（公元前 771-221年）中国中原地区57名儿童的饮食，以探索早期饮食与生物性别、社会性别之间的关系。通过对序列 采样的牙本质样本进行稳定同位素分析，我们重建了详细的儿童期饮食史。结果表明，从幼儿时期开始，男 孩饮食的δ15N平均值就明显高于女孩，这表明大多数男孩的饮食中消耗了更多动物蛋白，这种饮食习惯贯 穿于整个童年时期。在中国古代，肉类和粟黍等食物被高度重视，无论是有意还是无意，这些食物被更多的 喂给男性子嗣从而变得与性别相关。稳定同位素数据揭示了儿童与照顾者之间跨代互动的社会化过程，饮 食表达了当时的社会价值和社会性别，并通过发育中的儿童体现出来。 Keywords: 稳定同位素; 童年; 中国 Received 29 October 2022 Revised 05 April 2023 Accepted 10 May 2023 Childhood Food Practices as Socialization Processes in Ancient China64 Diet and nutrition are key components to health expe- riences over the lifetime and have significant effects on growth and development during early life and contin- ued effects into adulthood (Gamble and Bentley 2022; Gluckman et  al. 2007; Lewis 2018). Beginning from birth, nutritious and safe food is critical for all organ- isms (including liquids/drinks as “food”). However, humans approach food not only as a biological imper- ative but also as a medium that conveys sociocultural information (Appadurai 1981). The choices caretakers make about the foods given to infants and children are implicitly biocultural as they have significant biological and social meanings and effects. For example, infant feeding strategies (milk feeding vs. formula feeding, weaning timing, complementary food choices, etc.) are all culturally mediated practices that can have biologi- cal consequences for the developing infant (Miller 2018; Palmquist 2017). Consequently, anthropologists and health scientists have a long- standing interest in studying human diets and nutrition, both to improve health conditions in living populations as well as to un- derstand the cultural values we attach to cuisines. Here we utilize stable isotope analysis of tooth dentin and bone collagen samples to study diets of ancient Eastern Zhou individuals from the Central Plains of China (Fig. 1) over their lifetimes, with particular attention to childhood diets and the roles specific foods may have played in gendering individuals in early life. Food and Gender Food is a primary substance used in the socialization and enculturation of individuals and communities, as food practices are intertwined with culturally spe- cific understandings of age, gender, wealth, religion, Figure 1. Maps showing locations of Eastern Zhou archeological sites. Lower right map shows the archaeological sites of Changxinyuan, Gaolou, Tiancheng, and Xiyasi (part of the ancient Zhenghan city). Lower left map shows relative location of archaeological site Guomianyichang, approximately 26 km north of Xinzheng/ancient Zhenghan city sites. Miller et al. 65 politics, and more (Appadurai 1981; Douglas 2008; Hastorf 2017; Meigs 1987; Sterckx 2005, 2011; Weisman- tel 1988). Cultural identities are inextricably tied to foodways; indeed, a common way communities iden- tify “us versus them” is through comparisons of subsis- tence and cuisine (Appadurai 1981; Douglas 1984; Franklin 2001; Gaytán 2008; Harris 1985; Hesse 1990). Food practices and beliefs about what is or is not edi- ble, who consumes particular foods (when, how much, how often, in what context), and other values that foods are imbued with (such as what qualifies as “healthful” foods) are all learned behaviors that are routinely prac- ticed and embedded in our social interactions (Bour- dieu 1977; Lévi- Strauss 1966; Meigs 1987; Rozin et  al. 1997; Sterckx 2011). Caretaker/familial relationships are foundational to that socialization process via food; caretakers are responsible for ensuring adequate food intake for the young, and what qualifies as adequate/ proper meals for young people is culturally defined. From how infants are fed (breastfeeding, animal- milk feeding, formula feeding, etc.), to who makes the choices about weaning foods and what those are (and why), to later childhood diets and beyond, these are all small acts that normalize and idealize particular ways of being and convey significant amounts of social- cultural knowledge through their action and embodi- ment (Bourdieu 1977; Butler 1999; Farnell 2000; Mauss 1973; Meigs 1987; Mennell 1985; Taylor 1999). Within the field of bioarchaeology, “sex” is often a key variable in research design and is usually presented as a binary expression (male/female) of biological fac- tors (such as chromosomes, genes, gonads, hormones, etc.), with skeletal morphology being the primary lens of analysis, and this is not without problems or critique of assigning a binary gender construction to estimated biological sex (Agarwal and Wesp 2017; Fausto- Sterling 1993, 2012; Geller 2017; Richardson 2013; Sofaer 2006; Zuckerman and Crandall 2019; Zuckerman et al. 2023). Bioarchaeologists typically disambiguate “sex” from “gender” through the framework of viewing gender as a cultural construction; gender encapsulates socialized (learned) ways of being, embodied and performed (how to behave, speak, carry one’s self, emote, etc.), which includes culturally specific understandings of characteristics and behaviors that make one socially appropriate and identifiable according to shared un- derstandings of gender norms (Butler 1999; Geller 2017). One’s gender may or may not correspond to no- tions of an individual’s sex, though historians have noted that a sex- gender conflation existed in ancient China (Hinsch 2013, 2018; Nyitray 2021). Both external and internal conditions shape under- standings of gender, and these are historically contin- gent and change over time and space (Bourdieu 1977; Butler 1999; Farnell 2000; Taylor 1999). Gender/ gendering (gender expression, gendered embodiment) is a continuous process of both external (communal/ societal/institutional) as well as internal (personal/ psychological) interpretation and performance of nor- mative behaviors, expectations, beliefs, actions, and so on, such that society genders us and we are gendering ourselves through countless thoughts and acts (Butler 1999; Joyce 2000). Scholars have noted the insidious nature of gendering processes, which are often implicit, are nondiscursive, and normalize particular ways of being in the world as completely “natural,” which is achieved through countless choices and acts, usually without reflexive critical thought (Bourdieu 1977; Bou- veresse 1999; Butler 1999; Farnell 2000; Mauss 1973). Gender in particular is communicated through em- bodied performance (hexis; Bourdieu 1977), which makes studying these parts of humanity particularly challenging for scholars of the past. However, there are material things that are central to our socialization, and in this case, we investigate food as a primary me- dium for the communication of cultural values (see Geller 2017 on gender and the materially discursive). Food is embodied material culture, “that is, a special kind of material culture created specifically for imme- diate destruction, but destruction through the trans- formative process of ingestion into the human body . . . hence, it has an unusually close relationship to the per- son and to both the inculcation and the symbolization of concepts of identity” (Dietler 2007:222). While nu- merous materials reveal and communicate aspects of personal and shared identities and ideologies (clothing, for example), food is one of the few things humans im- bibe and whose components, both chemical elements and symbolic meanings, can become a part of the per- son. People have long looked to food, drinks, and other substances we consume as constructive, neutral, or de- structive elements in creating particular types of peo- ple (healthy, sickly, strong, weak, virtuous, corrupt, moral, pious, deviant, etc.), and this was certainly part of belief systems in ancient China (Sterckx 2011). These food valuations are learned and passed across genera- tions, which is not to say they remain static but in fact can be places where culture is demonstrably changing over time and can be studied through material traces in the archaeological record (Dietler and Hayden 2001; Hastorf 2017). Food can symbolize normative, aspira- tional, and inimical values, which in turn can be incor- porated and embodied by the consumer. Childhood is a critical period where one is figuring out how to be in the world (Lancy et  al. 2010), and learning gendered behavior is certainly a large part of this social developmental process (Montgomery 2010). It is through inter- and intragenerational interactions that particular ways of being are normalized over time. This socializing/learning of gender norms occurs both externally (through dialogue, through material cul- ture) but also internally (psychologically/personally), Childhood Food Practices as Socialization Processes in Ancient China66 recursively functioning as “boying the boy and girling the girl” (Butler 1999; Joyce 2000). It is these processes that begin in life as external that individuals then take up and carry on, or modify or reject over the course of their lifetime (Butler 1999). Food can act as a medium imbued with values related to gender, where cultural ideas about what a particular gender eats (or should eat) is passed on, re- enacted over time, normalized, and embodied. Children often lack the agency of choice when it comes to subsistence, with families typically exerting this power over young individuals (Lancy 2012). Therefore, through these acts of caretakers choosing food for infants and children, they are also implicitly communicating ideals and values through meals, which in turn create the literal body of the child. One of the earliest adult interventions in childhood feeding is the process of weaning a child off of (breast) milk using supplementary foods. This process is highly variable in its timing and tempo (Macadam and Dett- wyler 1995; Tomori et al. 2018). The weaning process has long interested anthropologists and health scien- tists due to the complex biosocial relationship formed between a mother/allomother and an infant, as well as the potential short- and long- term consequences for the health of the pair, particularly the developing child (Lewis 2007; Macadam and Dettwyler 1995; Tomori et al. 2018; Tomori et al. 2022). Beliefs and behaviors about when to begin weaning a child, how long that process should last, what supplementary foods should be given to an infant, or what foods should be actively avoided are primarily culturally dictated practices. Al- though infants typically need dietary supplementation beginning around age six months as metabolic needs outpace milk’s nutritional content, the addition of new foods into a child’s diet around this period are primar- ily cultural/personal choices (Dettwyler 1987; Fouts 2004; Halcrow et  al. 2018; Macadam and Dettwyler 1995). It is assumed that over the course of human his- tory, mothers (embedded in their larger social spheres) have primarily been making these decisions about when to wean their baby and the appropriate ways to do so. The length of time a child is weaned has often been related to ideas of parental investment, and the foods that children begin eating as they transition to a nonmilk diet may be especially revealing about deeply held cultural valuations ascribed to specific foodstuffs. While much of the anthropological work to under- stand human food practices in relation to culture and social identities is on living populations, we have his- torical and archaeological evidence for gendered diets in the past, including revelations made through the use of stable isotope analysis (Miller 2016; Miller et al. 2018; Reitsema and Vercellotti 2012; Soncin et al. 2021; White 2005). Our bodies reflect the chemistry of the foods we eat and the water we drink, with some caveats (Lee- Thorp 2008). Stable isotope analysis of bodily tissues is one technique bioarchaeologists fre- quently use for dietary reconstructions and can inform us of the plants and animals consumed during specific periods of life, depending on the tissue studied (Miller et al. 2018; Sealy et al. 1995). Carbon stable isotope data (δ13C) primarily tell us about the plant foods people ate as well as animal sources (DeNiro and Epstein 1978; Schoeninger and DeNiro 1982). Carbon isotope data are particularly useful in places where diets can in- clude both C3 and C4 plants, such as central China, where the traditional domesticated crop millet is a C4 plant, while primary C3 crops include rice, wheat, soy, and more (Farquhar et al. 1989). Nitrogen stable iso- tope data (δ15N) can be used to understand food webs and trophic positions, with increasing nitrogen values as one rises through the food chain (i.e., δ15N values can aid in distinguishing vegans from carnivores) (De- Niro and Epstein 1981; Minagawa and Wada 1984). Analyzing different tissues from the same individ- ual (i.e., bone and tooth) allows us to study dietary patterns from different periods of life, as well as differ- ent time scales of dietary averaging (Beaumont et al. 2018; Reynard and Tuross 2015; Tsutaya and Yoneda 2015). Bone is constantly remodeled over the lifetime while teeth are formed during youth and do not re- model. We can now subsample the dentin of a single tooth using an incremental/serial approach to create a detailed chronology of isotopic signatures across the developmental window of that tooth (Burt and Garvie- Lok 2013; Eerkens et al. 2011). For this study, targeted sampling of a permanent first molar provides dietary evidence spanning from around birth to 10 years of age, while sampling a permanent canine informs us of di- etary patterns roughly from the ages of one to 14 years (AlQahtani et al. 2010; Hillson 2005). In contrast, bone chemistry reflects the average diet from at least the fi- nal decade before death (Ambrose and Norr 1993; Fahy et al. 2017). By studying a bone and tooth sample from individuals who died as adults, we can examine dietary patterns over the life course in conjunction with vari- ous biosocial variables such as sex and age (Miller et al. 2018). Therefore, we approach the body as a ma- terial record of dietary practices during life and use the chemical signatures locked in bodily tissues to try and understand the biosocial roles that foods played in an- imating that life (Sofaer 2006; White 2005). Life in Eastern Zhou Period China The Eastern Zhou period (Spring and Autumn period 771– 476 BCE and Warring States period 475– 221 BCE) is a pivotal era of Chinese history as numerous po- litical, technological, and ideological changes were Miller et al. 67 under way. This is a time of political instability, with many states frequently in conflict and at war, termi- nating with the final Zhou ruler deposed and the uni- fication of early China by Qin Shihuang (Feng 2013; Liu and Chen 2012; von Falkenhausen 2006). Philos- ophers such as Confucius, Mencius, and Mozi lived during the Eastern Zhou period, and their ideologies were recorded and canonized over time, cementing cultural philosophies, including idealized behaviors and normative social roles, which in turn were being shaped in response to earlier Chinese history, as well as becoming archetypes for future generations to model/modify (Feng 2013; Hinsch 2003; Liu and Chen 2012; Sterckx 2005; von Falkenhausen 2006). Texts that relate to this period of Chinese history are themselves revised products. For example, many of the writings attributed to Confucius were assembled by disciples in the Han Dynasty period (206 BCE– 220 CE). Conse- quently, these texts reflect later compilers selecting particular rules, lessons, and fables that uphold the highest standards of moral order to inspire people to live up to, as well as reflecting aspects of class, gender, clan, and so on (Hinsch 2013). By the Han Dynasty pe- riod, society was patriarchal, and these texts are pri- marily devoted to the experiences of men, and elite men at that, with far fewer passages dedicated to wom- en’s experiences, which in and of itself suggests a lower value afforded to women and their diminished power within these societies (Hinsch 2013, 2018). Gender roles appear to be increasingly codified during this time, with most political and public- facing power concentrated in the hands of men, including control of wealth, land, inheritance, and so on. In con- trast, women’s roles emphasized the family and domes- tic sphere, with great weight placed upon women for producing children, particularly a male heir (Hinsch 2013, 2018; Nyitray 2021). The well- known phrase “men plow, women weave” (nangeng nüzhi) is thought to have its roots in even earlier times in China and articulates a gendered division of labor while also symbolizing the larger culturally sanctioned gendered separations that existed along many axes of daily life (Hinsch 2013). His- torians have argued that these bifurcations between men and women’s roles evolved over time and that ear- lier generations (such as the Shang and Western Zhou Dynasties) laid the foundation for an ideological shift to occur during the Eastern Zhou period, one that created a more stark contrast in idealized gender relations and whose philosophies related male– female duality of per- ceived biological sex to individual and familial morality and virtue, as well as good governance and political sta- bility (Hinsch 2013, 2018). While women are underrepresented in ancient texts, the passages that do relate to women often focus on the domestic sphere and filial piety, as Hinsch (2013) summarizes: “(a) woman should ideally hide herself within the recesses of the home, sacrifice her desires so she could cater to her husband and his kin, and obey her spouse and senior in- laws. Conversely, a man was free to leave the home and enter the wider world, pur- sue personal interests apart from his family, and exer- cise authority over his wife. Separation of the sexes had become a justification for wide- ranging masculine privilege” (Hinsch 2013:25). Wealthy families had the economic means to segregate parts of their daily lives and socialize primarily in homosocial spheres (men out in the world with men, women cloistered at home with other women and children), but this was certainly not the case for most common people whose daily in- teractions would have likely been structured but po- tentially less gender- divided out of practical necessity (Hinsch 2013). Though much more is known about life during these times for the ruling and elite classes, cer- tain aspects of gender roles, particularly related to the roles of girls as daughters, and women as wives and mothers responsible for producing and caring for chil- dren, were likely shared across many social dimen- sions, including class and clan groups (Hinsch 2018). The Liji, also known as the Book of Rites, provides further insights into the Eastern Zhou sex– gender bi- nary, which clearly began in childhood with children treated differently based on their perceived sex (exter- nal genitalia and associated reproductive capabilities) and gendered accordingly: 子能食食，教以右手。能言，男唯女俞。男鞶革，女 鞶絲. When the child was able to take their own food, they were taught to use the right hand. When they were able to speak, a boy (was taught to) respond with respect; a girl, submissively and gentle. The former was fitted with a handbag of leather; the latter, with one of silk. 六年教之數與 方名。七年男女不同席，不共食。八年出入門戶及即 席飲食，必後長者，始教之讓。九年教之數日。 At six years, they were taught the numbers and the names of the cardinal points; at the age of seven, boys and girls did not occupy the same mat nor eat together; at eight, when going out or coming in at a gate or door, and going to their mats to eat and drink, they were required to follow their el- ders: the teaching of yielding to others now be- gun; at nine, they were taught how to number the days. 十年出就外傅，居宿於外，學書計，衣不帛襦 褲，禮帥初，朝夕學幼儀，請肄簡諒。At ten, (the boy) went to a master outside, and stayed with him (even) over the night. He learned the classi- cal books and calculation; he did not wear his jacket or trousers of silk; in the courteous man- ners he followed his early lessons; morning and evening he followed the etiquette of respecting Childhood Food Practices as Socialization Processes in Ancient China68 the elders; he would ask to be exercised in (read- ing) the tablets, and learn to be honest. 女子十年 不出，姆教婉娩聽從，執麻枲，治絲繭，織紝組紃， 學女事以共衣服，觀於祭祀，納酒漿、籩豆、菹醢， 禮相助奠。A girl at the age of ten ceased to go out (from the women’s apartments). Her governess taught her the arts of pleasing speech and man- ners, to be docile and obedient, to handle the flax fibers, to deal with the cocoons, to weave silks and to learn (all) woman’s work, how to furnish garments, to watch the sacrifices, to supply the li- quors and sauces, to fill the various stands and dishes with pickles and brine, and to assist in set- ting forth the appurtenances for the ceremonies. 十有五年而笄，二十而嫁；有故，二十三年而嫁。聘 則為妻，奔則為妾。凡女拜尚右手。At fifteen, she assumed the hair- pin; at twenty, she was married, or, if there were occasion (for the delay), at twenty- three. If there were the betrothal rites, she became a wife; and if she went without these, a concubine. In all salutations of females, the up- per place was given to the right hand. (Liji, Nei Ze, 76– 82; translation by authors) Here we see a clear sex– gender binary from a young age with a number of specific ages called out as chronological markers of particular life events de- pending on the gender of the individual, and clear demarcation of gendered work begins from a young age. All of this points to deeply embedded notions of a gender binary and an implicit hierarchy where males are given greater power in the public domain, while fe- male power is limited to the domestic sphere (Hinsch 2013, 2018). We acknowledge that the layering and intersections of various experiential variables (age, gender, social status, ethnicity, etc.) means that while we may focus on one of these, in this case gender, we recognize these axes rarely operate independently and singularly; therefore, our interpretations may be clouded by in- dividual factors we cannot comprehend, qualify, or quantify at this time. Recently, feminist and queer cri- tiques of understandings of gender in China’s history have pushed researchers not only to expand studies to include women in the past but also to study masculin- ity, as well as to view gender beyond a dichotomous perspective (Chiang 2012; Hinsch 2013, 2018; Louie 2002; Nyitray 2021). It is certain that different ideas and norms for gendered behavior existed for individ- uals of different social classes, ethnic groups, and so on in ancient China (Hinsch 2013, 2018; Ko 2007; Ny- itray 2021). This research starts to touch upon those intersections of gender with other experiential identi- ties through the presentation of selective individual case studies. Evidence of Eastern Zhou Cuisines Archaeological and historical evidence indicate the importance of particular plants and animals in the di- ets of Eastern Zhou peoples (Dong et  al. 2017; Lee et al. 2007). Millet is the locally domesticated crop and dominated diets for millennia (Cohen 2011; Lee et al. 2007; Liu et al. 2009; Zhao 2011), while grains such as rice (domesticated from the south) and wheat (intro- duced from the west) appear less frequently in archae- ological assemblages in this region during this time (Chen 2016; Deng et al. 2019; Fuller et al. 2009; Guo and Jin 2019; Jiang and Liu 2006; Zhou and Garvie- Lok 2015). Historical texts reference specific foods, and the contexts of these references can provide hints as to the valuation and cultural meanings ascribed to some of these foodstuffs. For example, in many his- torical texts such as the Analects of Confucius, the Liji, and the Huang Di Nei Jing, millet is repeatedly men- tioned and is qualified as the traditional, highly de- sired grain. In contrast, wheat and soybean were considered “coarse” foods and therefore less valued, both symbolically as well as monetarily, with higher prices recorded for millet during the later Han Dy- nasty. Soybean and wheat were also known as reliable foodstuffs for feeding the poor and were even used to feed soldiers during military campaigns (Yu 2016). Grains such as millet, rice, and wheat were also turned into alcoholic beverages, and these wines are often mentioned in historical texts in relation to elite men’s sociopolitical interactions, as well as rituals honoring ancestors (Chang 1977; Liu and Reid 2020; Liu et al. 2020; Sterckx 2005, 2011; Yu 2016). Importantly, mil- let is isotopically distinct from most other plants that humans consume because it is a C4 plant, with δ13C values ranging from − 14‰ to − 8‰. In contrast, C3 plants, such as rice, wheat, barley, and soybeans, have δ13C values around − 23‰ (An et al. 2015; DeNiro and Epstein 1978; Farquhar et al. 1989; Kohn 2010; O’Leary 1988; Wang et al. 2018). Meat was also given high value both economically and socially, particularly holding significant power for honoring ancestors and performing rites (see Knapp 2019; Liji Wang Zhi 31; Sterckx 2019). Meat was also thought to have been infrequently consumed by the majority of people, particularly beef and lamb, which were highly prized and very expensive. Rather, these were meats of the upper classes, while pork and chicken, in particular, were more likely the occasional meat protein sources for commoners and poorer folks (Chang 1977; Yu 2016). Nitrogen isotope values can provide information about protein consumption, with stepwise enrichment of +3– 5‰ in δ15N as one rises through the food chain (DeNiro and Schoeninger 1983; Minagawa and Wada 1984; Schoeninger and Miller et al. 69 DeNiro 1984). Isotopic analysis of a small number of zooarchaeological samples (pig, dog, cattle, sheep) from two Eastern Zhou sites in ancient Zhenghan city (Changxinyuan and Tianli) indicate animals raised on diverse resources (Dong et  al. 2017; Miller et  al. 2020). The δ13C values ranged from − 18.6‰ to − 6.8‰, and δ15N values ranging from 2.4‰ to 10.7‰. Recent bio archae ol o gi cal research using stable isotope anal- ysis has documented dietary differences between nobles and commoners, with nobles/high- status indi- viduals having the highest nitrogen values, indicat- ing greater meat consumption and often consuming greater amounts of millet (or rice), which were also highly valued (Wei et al. 2021; Zhou 2020; Zhou et al. 2021). Previous bio archae ol o gi cal research on life for peo- ple living during the Eastern Zhou period has shown links between diet, sex, gender, and increasing social inequalities (Dong et al. 2017; Miller et al. 2020). Spe- cifically, bio archae ol o gi cal evidence has shown dietary differences between males and females during adult- hood, with males consuming more of the traditional and highly valued grain of millet, as well as more meat, while females consumed more of the relatively newly introduced cereals, wheat and soy (Dong et al. 2017; Miller et al. 2020). A recent study of 23 individuals from ancient urban Zhenghan city (Xiyasi, 西亚斯, and Chanxingyuan, 畅馨苑; Fig. 1) using incremental dentin samples suggested that aspects of these dietary patterns began during childhood, with boys consum- ing more C4 foods (millets) than girls, starting in youth, but overall, individuals consumed more C3 foods (wheat, soy, rice, etc.) during childhood in com- parison to their later adulthood diets (Miller et  al. 2020). Here we focus on the stable isotopic data from 34 newly studied Eastern Zhou individuals in addition to drawing on the previously published data from 23 other urban Zhenghan Eastern Zhou people (Miller et al. 2020) in order to illuminate childhood dietary patterns with particular attention to understanding dynamic relationships between food, sex, and gender. These dietary data from Eastern Zhou period individ- uals are from three newly studied archaeological sites from Henan Province on the Central Plains of China (Fig. 1): Gaolou (郜楼), Tiancheng (天成), and Guo- mianyichang (国棉一厂). Two of the sites, Tiancheng and Gaolou, are from ancient urban Zhenghan city, located under present- day Xinzheng. The third site, Guomianyichang, is located about 26 km to the north of ancient Zhenghan city, in the modern Longhu town, near Zhengzhou. Guomianyichang is located near the ancient city of Huayang, which was a military outpost, though the relationship between those two sites is still unclear. Archaeological research on these sites and associated excavated materials is ongoing (see Supple- mental Information for more information). Materials and Methods Skeletal samples (both a tooth and a bone sample) from 34 Eastern Zhou period individuals from three archaeological sites (Gaolou, Tiancheng, and Guo- mianyichang) were analyzed using isotopic methods. We studied nine individuals from Gaolou (five females, four males) and nine individuals from Tiancheng (five females, four males). Due to preservation issues, we are missing bone collagen isotopic data for three indi- viduals from Tiancheng. From Guomianyichang, 16 individuals were studied (six females, seven males, three unknown skeletal sex). Ongoing analyses of archaeological materials, including further human osteological analyses, prevent complete assessment of the nature of these cemeteries. No radiocarbon dates have been analyzed from these locales, but artifacts and stratigraphy indicate all burials presented here are from the Eastern Zhou era, and in some cases, this can be refined further to either the Spring and Autumn period or the Warring States period (see Supplemental Information). Some burials are be- lieved to have been disturbed and looted in the past and therefore we are cautious in the use of mortuary treatment and associated grave goods, as these may not accurately reflect the original burial treatment and are also known to reflect the actions of the living and not necessarily the status of the deceased. Individuals were selected for isotopic analysis based on preservation of skeletal elements to estimate sex and age, as well as presence of a permanent canine or first molar with minimal wear. Skeletal sex and age were estimated using standard osteological observa- tions of the pelvis and skull (Brooks and Suchey 1990; Buikstra and Ubelaker 1994). Almost all were adults at the time of death, so these individuals are survivors, in that most did not die as youths. Individuals were grouped in broad age categories of “juvenile” (esti- mated age of death as less than 18 years; n = 2), “young” (estimated age at death from 18 to 29  years; n = 10), “middle” (estimated age at death between 30 and 49; n = 8), or “older” (estimated age at death 50+; n = 8). Six individuals were more challenging to narrow their estimated age at death, so five are listed with two po- tential age categories, and one is noted as an adult (over 18 years at age of death). Of the 34 new individ- uals studied, 16 were estimated to be females, 15 were estimated to be males, and three were of unknown skeletal sex. A permanent first molar or canine tooth was preferentially selected to capture the early years of diet (however, one individual’s childhood diet is Childhood Food Practices as Socialization Processes in Ancient China70 represented by a second molar, Guomianyichang M109). Teeth were gently cleaned and silicone molds were created prior to destructive analysis. Bone sam- ples were preferentially taken from elements that were already broken. Tooth dentin segments were prepared for isotopic analysis following previously published protocols (Beaumont and Montgomery 2015; King et al. 2018; Sealy et al. 1995; Sealy et al. 2014). For dental samples, enamel was removed using a handheld rotary tool and preserved for future analyses. The remaining dentin tissue was placed in labeled beakers with dilute HCl (0.5 M) until the tissue demineralized sufficiently to be sliced with a scalpel. Any adhering cementum and/or secondary or tertiary dentin was removed when noted. Tooth samples were carefully sliced into ~1 mm increments beginning from the occlusal sur- face of the crown and proceeding to the root tip, us- ing a clean scalpel and metric ruler. Individual dentin slices were placed into labeled microcentrifuge tubes with 0.5 M HCl until further demineralized. Samples were rinsed repeatedly with pure water to neutrality, and then dilute HCl of 0.001 M (pH 3 solution) was added to samples before gelatinizing them for 24 hours in a 75°C oven. Samples were then agitated to mix and frozen prior to freeze- drying. Bone samples followed a similar protocol. Cortical surfaces were first cleaned and then bone was crushed and sieved, with the 0.25 mm to 1 mm fraction used for collagen extraction. Bone samples were demineralized in 0.2 M HCl (replaced as needed until demineralization was complete) and then rinsed with purified water to neutrality. Samples were then treated with 0.125 M NaOH for 20 hours and then rinsed to neutrality. Di- lute 0.001 M HCl was added to each sample before placing them in a 70°C oven for 48 hours. Samples were then frozen and freeze dried. Freeze- dried collagen samples were weighed into tin capsules for isotopic analysis at the Joint Interna- tional Research Laboratory for Environmental and So- cial Archaeology at Shandong University, Qingdao, China, using a Flash 2000 HY elemental analyzer cou- pled to a Delta V Advantage IRMS. Samples were an- alyzed in conjunction with calibration standards, including USGS40 (L- glutamic acid, δ13C = − 26.39‰ ± 0.04‰, δ15N = − 4.52‰ ± 0.06‰), USGS62 (caffeine, δ13C = − 14.79‰ ± 0.04‰, δ15N = +20.17‰ ± 0.06‰), USGS41a (L- glutamic acid, δ13C = +36.55‰ ± 0.08‰, δ15N = +47.55‰ ± 0.15‰), and internal standard of EMA B2155 (casein). The lab reports precision of ± 0.1‰ for δ13C and ± 0.2‰ for δ15N. Collagen quality was assessed by %C, %N, and atomic C:N, with all sam- ples reported here having C:N values between 3.1 and 3.6 (DeNiro 1985; Guiry and Szpak 2021; Schwarcz and Nahal 2021). A general developmental timeline for each tooth was used to facilitate interindividual comparisons as well as allowing for comparisons of dentin isotopic data across studies. With M1, we assumed the devel- opmental range began at birth (0 years) and completed at 10 years, while for canines, we placed the maximums at six months (0.5 years) to 14 years. Age estimations of each segment were calculated using the Beaumont and Montgomery (2015) method, which relies on a simple, linear relationship between the total time a tooth was growing (for example, 10 years for a first mo- lar) and the number of segmented samples extracted by a researcher. The result is an estimated median age point for each incremental sample and which provides a standardized approach that allows comparison to previous studies (Miller et al. 2020). However, dentin is not deposited in horizontal layers throughout the tooth structure, meaning that the slices created through the protocol will inevitably capture overlap- ping periods of dentin development, and therefore, as- sociated time frames for each segment should be considered an estimated average with potentially fuzzy boundaries rather than absolutes (Beaumont et  al. 2013; Tsutaya 2020). Results The incremental dentin samples from Eastern Zhou individuals from Gaolou, Tiancheng, and Guomiany- ichang (n = 34 individuals with n = 393 paired δ13C and δ15N values, Supplemental Tables 1 and 2) show a wide range of δ13C values, from − 19.8‰ to − 7.6‰, and δ15N values range from 6.2‰ to 14.3‰. Examining the individual dietary profiles (Figs. 2– 4), many individ- uals show characteristic declines in δ15N in the first years of life, indicating the process of removing breast milk from the diet (weaning), as well as changes to δ13C values across childhood years related to differen- tial consumption of C3 and C4 plants. These same in- dividuals (n = 34) have bone collagen values that range from − 15.7‰ to − 8.8‰ and δ15N values from 6.1‰ to 10.5‰ (Figs. 2– 4, Supplemental Table 1). The dentin profiles of individuals from the Eastern Zhou ancient Zhenghan city archaeological sites of Xiyasi and Changxinyuan are replotted in Supplemental Figures 1 and 2, and their data are included in subsequent anal- yses of Eastern Zhou dietary patterns (for all original Xiasyi and Changxinyuan data, see Miller et al. 2020). Figures 5 and 6 plot the incremental dentin isoto- pic profiles from all of the Eastern Zhou individuals we have studied to date (Gaolou, Tiancheng, and Guo- mianyichang in this study and Xiyasi and Changx- inyuan data from Miller et al. 2020) and use a loess curve to show the moving average for δ15N and δ13C Miller et al. 71 across the childhood years in conjunction with esti- mated skeletal sex (n = 54; 27 females, 27 males). Over- all, we see a high degree of isotopic heterogeneity, with large ranges observed in nitrogen, but especially in carbon isotope values, suggestive of differential di- etary practices between children, as well as revealing an expansive diversity in the foods that were consid- ered acceptable to feed growing children. A patterned difference is observed across childhood in the dentin δ15N values (Fig. 5), where the male average is consis- tently slightly higher than the female average, indicat- ing slightly more protein consumption (or proteins from a higher trophic position). The offset suggests a meaningful difference in dietary practices. Addition- ally, for most of childhood, females have slightly lower average dentin δ13C values, indicating more C3 foods in their diets compared to their male peers (Fig. 6). We estimated the weaning ages for a total of 47 Eastern Zhou individuals (28 individuals from this study plus data from 19 individuals studied in Miller et al. 2020) who have the earliest dentin segments pres- ent in their profiles (Table  1; Supplemental Table  1). To estimate weaning ages, we looked for declines in δ15N by 1‰ to 4‰, with potential concurrent changes to δ13C values across the earliest forming dentin, and that are associated with the removal of milk from the diet (Burt and Amin 2014; Eerkens et al. 2011). Indi- viduals (n = 10) who are missing the early forming dentin tissue or those with isotopic data that do not fit the expected drop in δ15N were excluded from wean- ing age estimations. Across the 47 individuals exam- ined, the average weaning age is estimated at 2.9 years of age, with no statistically significant difference (Wilcoxon rank sum test p = 0.759) in weaning age Figure 2. Isotopic profiles for individuals from Gaolou (n = 9; n = 5 females; n = 4 males). δ15N values (solid plotted line with circles shows dentin collagen values and horizontal line is bone collagen value) and δ13C values (dashed plotted line with circles shows dentin collagen values and dashed horizontal line is bone collagen value) are presented. Childhood Food Practices as Socialization Processes in Ancient China72 estimates between females (n = 20, average = 3.0 years) and males (n = 24, average = 2.9 years). These ages are estimates in that the dentin samples capture overlap- ping periods of development due to the way dentin tissue grows as well as the sampling procedure, and coupled with the fact that every individual’s develop- mental timeline will vary (i.e., timing of tooth growth). Therefore, these estimates should be treated as fuzzy averages rather than absolutes. Diets in the first few years of life are a complex com- bination of a mother’s (or allomother’s) diet (via milk) and the weaning foods consumed. Since the isotopic data indicate the average age of weaning was three years, we used the age of five years as the cutoff for comparing means (δ15N; δ13C) between females and males, which should represent diets that do not in- clude the influence of milk (mother’s diet) and only reflect the diet of the individual (Tables 2 and 3; Sup- plemental Table 1). There is a statistically significant difference in childhood diets post five years between males (mean δ15N = 8.5‰; mean δ13C = − 13.3‰) and females (mean δ15N = 7.8‰; mean δ13C = − 14.0‰) for both elements. All δ15N values were pooled (not aver- aged by individual) and appear bimodally distributed for both males and females, with males’ distribution shifted slightly higher on δ15N values (Wilcoxon rank sum test, p = 1.21e- 07). All δ13C values post age five years were compared between males and females (values pooled, not averaged by individual), and males were normally distributed but females were not (Wilcoxon rank sum test, p = 0.0018). We further compared the means of dentin samples of females and males be- tween ages five and 10 years, which is the overlapping developmental period first molars and canines cap- ture. The 27 males (represented by 139 dentin sam- ples) had a mean δ15N = 8.5‰, which is statistically significantly different from the 27 females (represented by 144 dentin samples) who had a mean δ15N = 7.8‰ (Wilcoxon rank sum test, p = 3.086e- 5). The female mean δ13C (27 females, n = 144 samples) of − 13.9‰ is statistically significantly different from the male mean δ13C (27 males, n = 139 samples) of − 13.2‰ (Wilcoxon rank sum test, p = 0.006). This suggests there are mean- ingful differences in diets between boys and girls. On average, females have lower average δ15N and δ13C values than males during childhood (postweaning). Bone collagen values are compared for these same Eastern Zhou individuals to examine possible dietary Figure 3. Isotopic profiles for individuals from Tiancheng (n = 9; n = 5 females; n = 4 males). δ15N values (solid plotted line with circles shows dentin collagen values and horizontal line is bone collagen value) and δ13C values (dashed plotted line with circles shows dentin collagen values and dashed horizontal line is bone collagen value) are presented. Miller et al. 73 Figure 4. Isotopic profiles for individuals from Guomianyichang (n = 16; n = 6 females; n = 7 males; n = 3 unknown skeletal sex). δ15N values (solid plotted line with circles shows dentin collagen values and horizontal line is bone collagen value) and δ13C values (dashed plotted line with circles shows dentin collagen values and dashed horizontal line is bone collagen value) are presented. Figure 5. δ15N dentin profiles for each Eastern Zhou individual studied across the Gaolou, Tiancheng, and Guomianyichang sites as well as the δ15N dentin profiles of individuals from Xiyasi and Changxinyuan (Miller et al. 2020). Female and male dentin profiles are plotted. A loess curve was plotted for males and females, and it shows that on average, male children had slightly higher δ15N values than their female peers across infancy and childhood. Figure 6. δ13C dentin profiles for each Eastern Zhou period individual studied across the Gaolou, Tiancheng, and Guomianyichang sites as well as the δ13C dentin profiles of individuals from Xiyasi and Changxinyuan (Miller et al. 2020). Female and male dentin profiles are plotted. A loess curve was plotted for males and females, and for much of the childhood period, females had slightly lower δ13C values compared to their male peers. Childhood Food Practices as Socialization Processes in Ancient China74 differences in later life (Tables 4 and 5; Supplemen- tal Table 1). There are no statistically significant dif- ferences between the average δ15N (Wilcoxon rank sum test, p = 0.762) and δ13C (Wilcoxon rank sum test, p = 0.079) bone collagen values of females and males. Interestingly, the degree of difference between the childhood dentin and later life bone collagen δ15N values decreases between females and males, while the average δ13C values become more divergent in adulthood. Table 1. Eastern Zhou Estimated Age of Weaning Eastern Zhou Count (n) Median (years) Mean (years) SD (years) Overall 47 2.8 2.9 0.6 Males 24 2.7 2.9 0.7 Females 20 3 3 0.7 Unknown 3 2.8 2.9 0.5 Table 2. Summary of δ15N Dentin Values Post Age Five Years Sex Number of Dentin Samples Median δ15N (‰) Mean δ15N (‰) SD (‰) Female (n = 27) 168 7.9 7.8 1.2 Male (n = 27) 159 8.6 8.5 1.3 Table 3. Summary of δ13C Dentin Values Post Age Five Years Sex Number of Dentin Samples Median δ13C (‰) Mean δ13C (‰) SD (‰) Female (n = 27) 168 – 14.5 – 14 2.8 Male (n = 27) 159 – 13.2 – 13.3 2.5 Table 4. Summary of Bone Collagen δ15N for These Eastern Zhou Individuals Sex Number of Dentin Samples Median δ15N (‰) Mean δ15N (‰) SD (‰) Female 27 8 8.1 1.1 Male 27 7.9 8.2 1.1 Unknown 3 6.9 Table 5. Summary of Bone Collagen δ13C for These Eastern Zhou Individuals Sex Number of Dentin Samples Median δ13C (‰) Mean δ13C (‰) SD (‰) Female 27 – 11.4 – 12 2 Male 27 – 10.9 – 11 1.8 Unknown 3 – 13.8 Discussion Feeding children as gendering practices: Childhood diets Overall, the dentin isotopic values for Gaolou, Tiancheng, and Guomianyichang individuals show a very wide range, from diets composed primarily of C3 plants to diets heavily reliant on C4 plants, and nu- merous mixtures between these extremes. There was also differential consumption of proteins (relatively more or less and/or proteins from different trophic positions) (Figs. 2– 4). We see that dietary variation occurs both within the same person’s diet over the course of childhood, in comparison with their later bone collagen values, and between individuals. This high degree of diversity in the isotopic values during childhood indicates that people living in this region had access to many different kinds of plant and ani- mal resources and that a large spectrum of items were considered foods that were appropriate to feed grow- ing children. Surprisingly, when we aggregate all of the incre- mental dentin values for Eastern Zhou individuals we have studied from this region so far (Fig. 5), we ob- serve a small but consistent offset in the average δ15N values between males and females across infancy and childhood. In general, females have lower δ15N values when compared with males. Stable nitrogen isotope values primarily reflect the proteinaceous foods of the diet, and differences between individuals may be evi- dence of more or less protein consumed or different types of proteins consumed (i.e., plant proteins vs. an- imal derived proteins). That individuals we assessed as biologically male show, on average, higher δ15N val- ues across their childhood years compared with the individuals assessed as biologically female reveals that males were fed a bit more meat, or proteins from higher trophic levels, when they were children. In con- trast, the females we studied generally received a bit less meat in their diets or instead consumed lower tro- phic proteins (potentially more plant- derived pro- teins) as youths. Patriarchal Eastern Zhou society valued males more than females, and meat was also highly prized. We propose that caretakers fed male children more meat than female children, and whether intentionally or not, meat became tied to the creation of male bodies and embodiment of male gender roles, including conveying notions of social worth. Furthermore, the δ15N offset occurs across the en- tire period of dentin development represented, begin- ning in the very earliest period of life. Across childhood but especially during the first years of life, it was likely mothers who were the primary caretak- ers making choices about the feeding habits of their Miller et al. 75 children and setting their dietary trajectories (though certainly mothers’ beliefs were embedded within cul- turally learned, normative frameworks). The earliest dentin segments capture the first couple years of life, when most infants were still consuming significant amounts of breast milk (see discussion of weaning, be- low). The fact that an offset between males and fe- males begins so early in life presents the possibility that the diets of lactating women may have even al- tered based on perceptions of their child. If male chil- dren were preferred, women who produced male heirs may have themselves benefited by being able to con- sume more meat in their own meals. This temporary access to a more coveted food item, meat, could cause a slight increase in the δ15N of their breast milk, which in turn would be consumed by their developing infant and resulted in the downstream effect, separating the δ15N dentin values observed between females and males during the earliest period of infancy. The per- sistence of the offset across all of the childhood years represented (and statistically significant difference in δ15N between boys and girls after age five years) indi- cates that, in general, male children were likely fed a little bit more meat than their sisters and other girls throughout this developmental period and that this was an ongoing embodied gendering practice across childhood. We also considered if there may have been any dif- ferences in childhood nitrogen isotope patterning within and between sites; perhaps meat consumption was related to factors such as geography (urban vs. nonurban communities), economic power, or access to particular foodstuffs. Comparing within and between sites, we see that the higher male offset in δ15N persists (Fig. 7). This suggests that notions that children deemed to be “boys” (highly desired male offspring) should be fed more meat in their diets because of their higher social value may have been widespread within Cen- tral Plains Eastern Zhou culture. There are a few in- dividuals who do not follow these patterns (a few females with high δ15N values, a few males with low δ15N values) who likely indicate how diet is also entan- gled in aspects of wealth, status, access, and other factors. It is in these dietary isotopic data sets that we can begin to access personalized and lived aspects of gender for Eastern Zhou people, discerning how food practices were entangled in gender norms and embod- ied gender expression, with specific foods fed to cer- tain individuals, which, over time, shapes that person into the embodiment of those cultural ideals. Figure 7. δ15N isotopic data profiles by site and by skeletal sex showing the same patterning of a higher average δ15N value for males than for females across all sites. Childhood Food Practices as Socialization Processes in Ancient China76 Although we believe this patterned offset in δ15N values for the dentin collagen samples was driven by cultural forces, we cannot rule out the possibility of a sex- based biological explanation. Physiological stress can change how the body utilizes energetic resources, which can alter tissue nitrogen stable isotope values (D’Ortenzio et al. 2015; Fuller et al. 2003; Fuller et al. 2006; Katzenberg and Lovell 1999; Williams et  al. 2011). Elevated δ15N values observed in hair or dentition samples have been interpreted as potential evidence for stress in past populations (D’Ortenzio et al. 2015; King et al. 2018; Miller et al. 2020), but these are usually short- term changes to a few individuals, and protracted stress across an entire group has (to our knowledge) only been observed by Beaumont and Montgomery (2016) in their study of victims of the Great Irish Famine. We believe it is unlikely that as a group, male children are experiencing heightened stress relative to their female peers, particularly in the patriarchal Eastern Zhou society with known male– female hier- archies. If not related to stress, perhaps boys metab- olize and incorporate dietary protein differently during childhood compared to females? However, most re- search using this isotopic methodology to study child- hood diets from other regions of the world finds little difference in isotope results used for assessing diets between males and females during childhood. Further, when dietary differences between females and males have been found, they have been explained as evi- dence for cultural behaviors, such as social differenti- ation via food practices, not as a biological phenomenon (Eerkens and Bartelink 2013; Ganiatsou et al. 2022). A few individuals we studied exhibit opposing covari- ance in nitrogen and carbon values (such as nitrogen declining but carbon values increasing; for example, see Guomianyichang M068). These patterns have been considered potential evidence of physiological stress (Beaumont and Montgomery 2016; Garland et al. 2018; King et al. 2018) but can also occur when a child is weaned onto a diet that is different from the milk they were previously consuming (i.e., mother’s diet). If an infant was weaned using foods that have more posi- tive δ13C values (such a millets) than what the lactating female had been consuming (captured in the milk), we would see nitrogen values continuing to decline (removal of milk from diet) while carbon values in- creased (consumption of foods like millets with higher δ13C values). Both of these hypotheses should be con- sidered in individuals whose values exhibit covari- ance, and other stress indicators (via paleopathological analyses) may also assist in these interpretations. Fu- ture studies may help to clarify if there are any under- lying physiological reasons that might cause such noted differences in nitrogen isotope values between growing children. When we aggregate the dentin δ13C isotope profiles for all Eastern Zhou individuals, we find that the av- erage is slightly lower for females than it is for males across most of childhood, and the means between the sexes are statistically different when we look at the val- ues after age five years (see loess curves in Fig. 6). This indicates that overall, female children were consum- ing a bit more C3- type foods while males were con- suming a bit more C4- type foods. If C4 foods, such as millets, were afforded a higher value (as indicated in historical texts), then the difference in childhood car- bon isotope values may demonstrate the preferential feeding of millets to boys and with slightly less of these foods (or drinks) given to girls. However, the patterns in these data appear more complex when we exam- ine the values within and between archaeological sites (Fig. 8). We previously found (Miller et al. 2020) that during childhood, females from Xiyasi and Changxinyuan generally consumed more C3 foods than males, who consumed more C4 foods (millets), and this pattern is also seen in the newly examined individuals from Tiancheng. However, the opposite pattern is found for those buried at the sites of Gaolou and Guomiany- ichang; the average δ13C value for males is lower than females, indicating females buried at those sites ate more millets during childhood than the males. The few individuals with the very highest δ13C values across childhood and the very lowest δ13C values across child- hood also all come from Gaolou and Guomianyichang (with one exception of a male from Changxinyuan who also has quite high δ13C values in childhood), and therefore the individuals who were interred in these cemeteries encompass the largest δ13C range in child- hood diets. When we examine the evidence at the in- dividual level, we see indications of relationships between isotope values, markers of grave wealth/ status/class, and life histories (see “Dietary patterns over the lifetime: Individual examples”). Here we may be seeing interacting effects of regional food practices and access to specific resources, in conjunction with experiences such as gender and class. Weaning patterns All Gaolou, Tiancheng, and Guomianyichang individ- uals studied with early life dentin segments show ev- idence for breastfeeding and weaning in their isotopic values. Our weaning age estimations for 47 of the Eastern Zhou individuals show that by around age three years of age, milk is no longer a detectable di- etary component for most, and there is no significant difference in the estimated weaning ages between fe- males and males. The earliest age we detected wean- ing termination was around 1.6 years (Gaolou, M100, Miller et al. 77 female; Supplemental Tables 1 and 2) while the latest age we estimated weaning completion was around 4.3 years (Guomianyichang, M090, female; Supple- mental Tables 1 and 2). Therefore, there is variability in the length of the weaning process, with most children completing weaning between ages 2.5 and 3.5 years. Historical texts provide information about the re- lationship between specific chronological and social ages, and they suggest that the age of three years was an important marker in a child’s life. For example, in the Liji, a Warring States and Han period document advising of social norms and ceremonial rituals, we learn, “食子者，三年而出，見於公宮則劬。大夫之子有食 母，士之妻自養其子. The nurse of the ruler’s boy quit the palace after three years, and the ruler meets her, and rewarded her for her toilsome work. The son of a Great Officer had a nurse. The wife of an ordinary of- ficer nourished her child herself” (Liji, Nei Ze, 74). This passage tells us a few very important things: (1) chil- dren were nursed (breastfed), (2) in almost all cases a baby’s mother was the one nursing the infant but ruling and upper- class elite families had access to wet nurses, and (3) children were nursed and closely cared for in this way for the first three years of life. Further evidence of the importance of the age of three is found in the Analects of Confucius through a discussion of proper mourning rites, where it is said deceased par- ents should be mourned for three years as that is the same amount of time that they intensely cared for their child at the beginning of their life (Chen [Confucius] 2017:215; see also Miller et al. 2020). These isotopic find- ings, in conjunction with historical references, sup- port the importance of the social age of three years in ancient Eastern Zhou culture. There is a large amount of variation in childhood diets (between individuals and within the same indi- vidual’s childhood years), revealed through the wide spread of nitrogen and carbon isotope values observed across the dentin data sets. This shows there was a high degree of variability in supplemental foods during weaning and the diets subsequently consumed across childhood. When we look more closely at the carbon isotopic profiles from the earliest years of life, we see that during the first two to three years of life, the male δ13C values are actually lower than the females. How- ever, the loess curve representing the male average δ13C values over time (average is the solid blue line and blue shaded band is the confidence interval of the mean; see Fig. 6) is almost flat across all of childhood, suggest- ing little change overall in the average male consump- tion of C3 and C4 plant- based foods (and animals consuming those resources). In contrast, the female Figure 8. δ13C isotopic data profiles by site do not show a standardized pattern between the sexes, suggesting this aspect of diet is not driven by gender alone but likely has many complicating factors such as location/region, class/wealth, and more. Childhood Food Practices as Socialization Processes in Ancient China78 δ13C average line shows a drop of about 2‰ across the first few years of life before leveling out slightly below the male line. This is the same period of time we be- lieve most individuals were still consuming some breast milk as they were slowly being weaned. Conse- quently, these data from the earliest years of life par- tially reflect a mother’s diet while she was breastfeeding as well as revealing the isotopic values of the dominant weaning foods. We suggest that the patterns in the δ13C averages indicate that infant girls’ diets were sup- plemented with more C3 foods (daughters given more meals with wheat, soy, rice, barley, etc.), while infant boys were generally weaned onto diets with slightly more C4 foods (millets). Mothers’ diets likely con- tained more C4 foods than the diets that they weaned their daughters onto, hence the ~2‰ decline as they were weaned off of millet- enriched milk and onto di- ets with more C3 solid foods. Sons were weaned onto diets that more closely resemble their mother’s diets (a bit more millet), hence the relatively flat loess curve for male δ13C across childhood. Dietary patterns over the lifetime: Gender and age For the Eastern Zhou people studied (n = 56), we cal- culated that on average, dietary δ13C increased by 1.9‰ between childhood and adulthood (comparing aver- age δ13C post age five to bone collagen δ13C; Tables 2– 5; Supplemental Table 1), meaning most individuals con- sumed slightly more C3 resources in childhood and then more C4 resources in adulthood. When divided by skeletal sex, we see that on average, female values (n = 27) increased between childhood and adulthood by 1.7‰, while male values (n = 27) increased by 2.1‰. Of 27 females, only seven had values in adulthood that were lower than their childhood values (i.e., their di- ets included more C3 foods as they aged), and further three of those individuals had change of less than 1‰ (so a relatively insignificant dietary change for those women). Of the 27 males, five had values in adulthood that were meaningfully lower than their childhood values (change was greater than 1‰), suggesting a shift to more C3 foods as they aged. These patterns show that most people’s diets changed slightly over their life course, and for the majority, that meant consuming a greater amount of C4- type foods, presumably millets, in adulthood compared to during their childhood years. This dietary influx of millet during adulthood may relate to better access to preferred foods for older individuals, as well as the consumption of millet- based alcoholic beverages (Liu 2021). The Liji provides multiple narratives on age- related dietary habits, such as passage 11 of the Nei Ze, which discusses the proper conduct for a recently married young couple who live with the husband’s parents: “ 父母在，朝夕恒食，子婦佐餕，既食恒餕，父沒母存，冢 子御食，群子婦佐餕如初，旨甘柔滑，孺子餕. While the parents are both alive, at their regular meals, morn- ing and evening the sons and their wives will serve them, and what is left after they will themselves eat. When the father is dead, and the mother still alive, the eldest son should accompany her at meals, and other sons and the wives will serve, and do with what is left as in the former case. The children should have the sweet, soft, and unctuous things that are left” (Liji, Nei Ze, 11). This passage reveals information about the fa- milial structure as well as how food is distributed within a household. The parents of the eldest son (parents- in- law from the wife’s perspective) hold the highest regard in the family, they are fed first, and what they do not eat is then left to the married cou- ple, and after that children (those of the younger mar- ried couple) are fed the remaining foods. The Liji text can be interpreted as a guide for how people (of par- ticular classes and means) should ideally comport themselves, and it presented guiding structures and principles for proper cultural behavior to maintain or- der in the family, clan, and state. Here we see how food- related behaviors are part of upholding the so- cial power structure. If as one ages, they get to select the better (preferred/more valued/tastier) portions of a meal, then we could see how consumption of partic- ular foods such as millet could be mediated by multi- ple aspects of life experience, including sex/gender, age, and status. Interestingly, within the 56 individuals we can cal- culate dietary change between their dentin and bone collagen samples, we find almost no change observed for δ15N. When we divide the sampled individuals by sex, we see that female δ15N values generally increase between childhood and adulthood, by an average of 0.3‰, while male values actually decrease by an aver- age of 0.2‰. Neither of these shifts are considered iso- topically meaningful, in that they are not indicative of a major dietary change (Pestle et al. 2014), though the slightly higher rate of change for females may in- dicate some benefit for particular women who had better access to meat in adulthood compared with childhood, while boys and men already generally had better access to meat compared with females and maintained that over their lifetime. Interestingly, the Liji again points to the intersections of multiple life variables and highlights how aging adults should be given privileged access to certain food if they are el- derly: “王制: 五十異粻，六十宿肉，七十貳膳，八十常珍； 九十，飲食不離寢、膳飲從於游可也. For those of fifty, the grain was (fine and) different (from that used by younger men). For those of sixty, flesh was kept in store. For those of seventy, there were two fine dishes Miller et al. 79 every meal. For those of eighty, there was a constant supply of delicacies. For those of ninety, food and drink were never out of their chambers. Wherever they wandered (to another place), it was required that savory meat and drink should follow them” (Liji, Wang Zhi, 56). Here we see how nicer grain and meat were considered particularly important foods for peo- ple as they aged, with the elderly ideally always hav- ing easy access to a tasty meal, especially meat; this hypothesis could be tested in future bio archae ol o gi- cal research focused on age- related dietary changes in adulthood. Dietary patterns over the lifetime: Individual examples Two of the females we studied from Gaolou have ex- ceptionally high δ13C values in childhood and that are retained into adulthood based on their bone collagen values, and both of these women also had markers of wealth in their burials. Individual M089 had both an inner and outer coffin (considered a more expensive grave), while M145 was buried with many pieces of pottery and a coffin decorated with cinnabar, and per- haps their (interpreted) higher status may have given them greater access to the desirable grain, millet, across their lifetimes. However, the relationships be- tween gender and wealth likely have interacting effects over the life course. For example, M082 was a female from Gaolou who also had a wealthier burial featur- ing inner and outer coffins, pottery, cowry shell, and cinnabar, but she has much lower δ13C values across childhood showing significant C3 food consumption. Her bone collagen value is over 3‰ higher than her final dentin sample, indicating she experienced a di- etary change to consuming more C4 foods in adult- hood, which may have been tied to a change in wealth/ status later in life. Similarly, Gaolou M115, a male, had the lowest δ13C values across his early childhood years within the whole Gaolou sample: the average δ13C across all his dentin samples = − 16‰, with the very final dentin segment δ13C = − 14.1‰, but his later life bone collagen δ13C = − 9.1‰, shows a very dramatic dietary shift between childhood and adulthood. Per- haps his social standing and wealth improved as an adult, he was buried with shell and cinnabar, and the later life shift to a diet rich in the desired grain, mil- let, could have also been a benefit if his social status improved. It is certain that gender was only one of many potential axes that diet was interacting with, and wealth and status would have played a major role in the foods people could afford to eat as well as what was considered appropriate and desirable cuisine. Un- fortunately, assessing large- scale relationships be- tween mortuary treatment and diet over the lifetime is challenging due to grave disturbances and plunder- ing in earlier times, limiting our ability to accurately assess all individuals’ treatment at death (see Materi- als section). The same patterning of average δ13C for males be- ing lower than females during childhood is also seen in the Guomianyichang sample. Guomianyichang may have been affiliated with a nearby military site and may not have had consistent access to the same food resources as Zhenghan city (Yang et al. in press). For example, individual M124 from Guomianyichang was an older aged male from the Spring and Autumn period, and his childhood carbon isotope values are the lowest of any Eastern Zhou male we have studied to date: average δ13C across all his dentin samples = − 19.1‰, with the very final dentin segment δ13C = − 18.3‰, but his later life bone collagen δ13C = − 11‰, showing a significant dietary shift between childhood and adulthood. He appeared to be buried without a tomb structure but had five pottery items interred with him. Perhaps M124’s social status increased over his lifetime and in his older age he was able to dine on more millet? Interestingly, another male from Guo- mianyichang, M068, also had very low δ13C values across most of his dentin samples, with an average δ13C = − 18‰ between birth and around age nine years. His final dentin sample, aged around nine to 10  years, shows a large change in δ13C to − 11.6‰, and this di- etary shift may have held through his later life as his bone collagen δ13C value is − 11.4‰. In contrast, M146 was a young adult woman who lived during the War- ring States period and upon death was buried in a sin- gle coffin, with one piece of pottery. Her childhood dentin δ13C values were very high (average = − 8.2‰), indicating a diet dominated by millets, but her final bone collagen value, − 14.2‰, shows a significant di- etary shift occurred for her and that she consumed much more C3- type foods as an adult. It might be pos- sible that some of the individuals who were buried at Guomianyichang were not born and raised in this area but instead moved here in association with the mili- tary post, and therefore their diets may have shifted if there were regional differences in the cuisines or access to particular ingredients. Therefore, gender may be an important factor in childhood dietary practices, but additional variables such as wealth or region/location may have played a larger role or dictated different di- etary customs for individuals or specific communities. Conclusions The unique relationships that humans have with the things that we eat make food- related data sets (bo- tanical and faunal remains, stable isotope data, dental Childhood Food Practices as Socialization Processes in Ancient China80 calculus data, iconographic representations, etc.) a rich medium to explore layers of the human experience that are inaccessible from other material remains in archaeological contexts. Technological advances are allowing for finer resolution of information that was previously out of reach, and attention to particular materials, such as dietary evidence from food studies, which is known to be laden with meaning (including environmental information, economic values, ideo- logical uses, understandings of sex, gender, age, health, wellness, etc.), offers us a window to aspects of hu- manity that are personal, are relatable, and can deepen our understanding of the shared and divergent parts of what it has meant to be human in particular times and places. Isotopic analysis of skeletal tissues pro- vides a rare opportunity to get to know the life history of a specific person from the past, and advances such as incremental segmentation of tooth dentin provide detailed pictures of specific periods of ancient lives. Here we have shown that dentin samples can reveal information about particular foods fed to children and the ways that communities thought about and imbued those foods with values. The observed pat- terning in the isotopic data reported here is pointing to something that goes beyond the simplistic act of eating; repeated processes of feeding children slightly different meals, such as differing amounts of meat or other protein- rich foods, appears to reflect socially constructed food- value systems intersecting with gen- der roles, which are enacted by caretakers using food (intentionally or not) as a material medium that both symbolically conveys gendered meaning as well as lit- erally creating a gendered body that is chemically dif- ferentiated through consumption of these meals over time. All humans become part of their culture and com- munities through socialization into myriad roles and shared understandings of normalized/naturalized ways of being. The Warring States period philosopher, Xunzi, related learning to be a cultured gentleman to the processes acting on individuals during key peri- ods of life through a simple analogy: “Through steam- ing and bending, you can make wood as straight as an ink- line into a wheel. And after its curve conforms to the compass, even when parched under the sun it will not become straight again, because the steaming and bending have made it a certain way” (Xunzi, tran- scribed by Hutton 2014:1). Gendered ways of being are historically contingent and learned (habitus) through observation, mimesis, modification, and re- iteration over generations (hexis), with individuals and social groups constantly making and remaking the boundaries and, in a sense, rules of how differently gendered groups should behave and exist in the world (Bourdieu 1977; Butler 1999). Some of these social processes are created through dialogue and may even be embedded within linguistic structures (such as gen- dered language), others are materially communicated (such as clothing) or enacted (such as the activities/ labor/products one can produce), and others, such as food, can operate along multiple dimensions, includ- ing uniquely being a material that becomes a part of the person’s body itself (Dietler 2007). Dietary prac- tices and the specific foods a person eats can be a part of gender identity and the gendering process. Child- hood is a critical period of dynamic biological changes and complex social learning, and gender identities are one of many human experiences that may be cata- lyzed beginning in early life. The fact that children lack the ability to feed themselves for the first years of life makes studying early childhood foodways an ex- ceptionally revealing space for illuminating social processes and the cultural values of specific foods, particularly as it speaks to the transgenerational as- pects of social reproduction. Through high- resolution dietary reconstructions of early life using an incremental dentin sampling ap- proach, we have seen how for Eastern Zhou peoples living on the Central Plains of China, one food type in particular, meat, reveals social values and gender inequalities, while also becoming part of the gender- ing process and gender embodiment itself. Caretakers, primarily mothers, were responsible for feeding their children, and therefore in studying early life diets, we are observing intergenerational interactions material- ized through food choice. Maleness becomes embod- ied through enacting particular characteristics that make up the category itself, and here we see mothers and other caretakers marking the maleness of specific children through the consumption of meat, and po- tentially millet to a minor extent, which in turn also marks female children in contrast to this (i.e., less meat consumption, less millet consumption). These gen- dered roles are relational and, in some ways, opposi- tional to one another, fitting within the dyadic frameworks of ancient Chinese philosophies, thought to create balance and harmony through their coexis- tence (Louie 2002). These dietary practices worked to create gendered bodies that were sensible in accor- dance with cultural norms and values, which fol- lowed particular ways of being in the world, including intersections with other aspects of identity, and rein- forced gendered notions through their existence and repetition across generations. 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