Tracking breastfeeding and weaning practices in ancient populations by combining carbon, nitrogen and oxygen stable isotopes from multiple non-adult tissues

This paper explores the potential of combining different isotope systems from different tissues to improve resolution when reconstructing breastfeeding and weaning practices (BWP) in archaeology. Additionally, we tested whether changes in diet can be detected in deciduous teeth. Rib collagen samples from 22 infants/children from the archaeological site of Bacuranao I (Mayabeque, Cuba) were processed for nitrogen (delta N-15) and carbon (delta C-13(co)) stable isotopes and assessed using a Bayesian model (WARN). In addition, enamel of 48 teeth from 30 infants/children were analyzed for oxygen (delta O-18(en)) and carbon (delta C-13(en)) stable isotopes. Data revealed that the timing of weaning cannot be characterized precisely by analyzing either delta O-18 or delta N-15. While a depletion in both delta N-15 and delta C-13(co) is only evident after one year, the WARN model suggested that the weaning process started at around 3 months and ended around 1.7 years. Most teeth were enriched in delta O-18(en) compared to deciduous incisors, suggesting a breastfeeding signal. However, a high variability in delta O-18 was found between similar teeth from the same individuals. Higher enrichment in delta O-18(en), and variability, was observed in tissues formed during the first six months of life. A delta C-13 enrichment of 1.0% was observed among deciduous teeth and ribs. While most individuals enriched in delta N-15 showed enrichment in delta C-13, the delta O-18 values were more variable. Our data suggests that stable isotopes of deciduous teeth, especially delta C-13(en), can be used to detect changes in diet during the weaning process. It is also possible that the delta O-18 enrichment observed in M1 is influenced by the effects of cooking techniques on weaning foods. The combination of multiple isotope systems and tissues overcome some of the limitations posed by single tissue approaches.