Reconstruction of African human diet using bone collagen carbon and nitrogen isotope ratios

Behavioural modifications associated with the exploitation of new food resources have been linked to major steps in hominid evolution and in subsequent human cultural development^1,2. Testing of specific hypotheses concerning the influence of dietary change on these processes would be facilitated by quantitative estimates of early hominid and human diets. Although most methods of obtaining such evidence provide only qualitative information², the stable carbon and nitrogen isotope ratios of animal tissues, and in particular, bone collagen, can be used to quantify the consumption of foods having different isotopic compositions^3-5. As reported here, analysis of the collagen of historic and prehistoric African human populations from Kenya, Tanzania and South Africa that have reasonably well-known diets shows that stable carbon and nitrogen isotope ratios in bone collagen can distinguish marine foragers from populations consuming terrestrial resources, pastoralists from farmers, farmers consuming grains from those consuming non-grain crops, and camel pastoralists from capri-bovine pastoralists.