Hydrogen isotope measurements of bone and dental tissues from archaeological human and animal samples and their use as climatic and diet proxies

Abstract

Stable hydrogen isotope measurement of body tissues faces analytical and interpretative challenges such as hydrogen exchange with atmosphere or competitive influence of drinking water and food intake. Samples from the Gallic site of Thézy-Glimont, France, have already been investigated isotopically for climate reconstruction and diet investigation of the buried individuals. This allows comparison with the hydrogen isotope composition (δ2H) of bone collagen, tooth enamel and of bulk bone measured for 8 humans and 11 animals. Three of the best-preserved human skeletons were incrementally sampled and show acceptable homogeneity of δ2H values of bone collagen (<5‰) and of bulk bone (<10‰) despite various turnover rates of these tissues. Human tooth enamel records breastfeeding as attested by δ2H values of pre-weaning teeth which are 2H-enriched by +20 to +30‰. We observe that the δ2H of bone collagen and bulk bone are strongly correlated. The δ2H signatures of bone collagen, tooth enamel and bulk bone record both climate conditions and dietary practices, as attested by linear relationships with traditional isotopic proxies (δ18O, δ13C, δ15N) which were previously measured on the same samples, although interpretations depend on the sampling strategy of each study. Measurements of δ2H in bulk bone and dental tissues are more readily achievable than collagen which requires extraction and purification and could become crucial in studies where bone tissue is scarce or when the only available remains are tooth material.