Raising girls and boys in early China: Stable isotope data reveal sex differences in weaning and childhood diets during the eastern Zhou era

OBJECTIVES: Using stable isotope analysis of incremental dentin segments, we reconstruct breastfeeding, weaning, and childhood dietary patterns of Eastern Zhou period (771–221 BC) individuals from the Central Plains of China. Previous isotopic research on the Eastern Zhou demonstrated dietary difference between male and female diets in adulthood via bone collagen analysis. To understand the development of gendered dietary patterns we must examine the early life period. We aim to identify the timing of the weaning process, whether childhood diets were the same as adulthood diets, and if there were differences between the diets of boys and girls during childhood. MATERIALS AND METHODS: We present incremental dentin and bone collagen δ(13)C and δ(15)N isotope data from 23 individuals from two Eastern Zhou archaeological sites (Xiyasi 西亚斯and Changxinyuan 畅馨苑). RESULTS: Weaning was completed between ages 2.5 and 4 years. Females were weaned slightly earlier than males. Early childhood diets show significant incorporation of C(3) foods, such as wheat and soybean, for almost all children, while later adulthood diets indicate greater incorporation of C(4) foods (millets), particularly for males. DISCUSSION: Childhood diets included greater amounts of C(3) foods than expected, suggesting that grains such as wheat may have been adopted in these communities as foods for children. Nevertheless, dietary differentiation between females and males began in childhood, with boys eating more millets (C(4) foods) than girls. The findings suggest that feeding children was a significant aspect of socialization and cultural gendering of individuals in ancient China.