Elucidating pre-columbian tropical coastal adaptation through bone collagen stable isotope analysis and bayesian mixing models: insights from Sambaqui do Moa (Brazil)

Over the last decades, the sambaquis from the Saquarema region (Rio de Janeiro, Brazil) have been subjected to systematic archeological investigations aimed at elucidating the lifestyles of Holocene populations that inhabited these coastal environments. The present study is an extension of these investigations and aims to elucidate the dietary information of 11 human individuals excavated from Sambaqui do Moa through the analysis of bone collagen stable carbon and nitrogen isotope compositions and Bayesian mixing models. The results reveal that marine and brackish fauna played dominant roles as sources of dietary proteins for all the individuals, while C3 plants were an important contributor to their overall diet, supporting the view that these groups had a mixed economy. Although all individuals presented a reasonably homogeneous diets, the isotopic results revealed noticeable differences between the two occupation phases, suggesting a dietary shift through time. There were also small differences between males and females. Further dietary studies on sambaquis from Saquarema are important to refine and expand our understanding of subsistence strategies in tropical coastal environments of eastern South America