Breatfeeding and weaning patterns among agro-pastoralists: New evidence of dentine isotopes in Northwest China during Bronze Age

•Dentine isotope results from the Bronze Age in northwest China reveal intragroup variations in weaning practices among agro-pastoral populations.•The differences observed in weaning patterns encompass both the timing and process of weaning, as well as the selection of complementary foods.•It is plausible that these divergences in weaning practices within communities could be attributed to economic specialization. As an integral part of all family life, childcare, including breastfeeding and weaning, has a significant impact on the healthy growth of infants. Understanding the lactation and weaning patterns of different economic groups is helpful for understanding the details of ancient human life. In ancient China, the breastfeeding and weaning patterns of some agricultural populations have been studied. However, the weaning patterns among ancient agro-pastoral populations are unclear. Here, we analyzed the carbon (δ13C) and nitrogen (δ15N) stable isotopes of dentine at the Bronze Age Chongpingyuan site to explore whether the composition of the childhood diet reflects the same mixed economic characteristics as those of the adult diet, which includes farmed millet and dairy products from animal husbandry. The results indicate that there are two main weaning patterns in the population of the Chongpingyuan site. Both weaning age and preference for complementary foods vary among populations. Children born to families primarily engaged in grain farming may be completely weaned before they reach three years of age, with plant-based C4 foods such as millet being their main source for complementary feeding. Conversely, children born to families primarily engaged in livestock raising are completely weaned after four years of age and consume more animal-based complementary food, such as goat dairy products. These new records highlighting different weaning patterns within communities provide valuable insights into understanding complexities within ancient Chinese societies.