Paleodiets of hunter-gatherers from the central Patagonian coast: Reviewing scopes and limitations of stable isotope analyses

This work reviews paleodietary reconstructions of hunter-gatherers from the northeast province of Chubut, Argentina. The isotopic record of human bone can complement information from zooarchaeological and technological studies with its particular resolution on the long-term diet of individuals. Previous δ¹³C and δ¹⁵N studies found dietary differences between the coastal area and the lower basin of the Chubut River, both in the proportion of marine resources in the diet and the trophic positions of prey. However, it is challenging to test hypotheses concerning human diets in northeastern Patagonia, where C₃ and CAM plants grow and terrestrial, riverine, and marine prey are available. Here, we focus on the local isotopic ecology to assess the scopes and limitations of δ¹³C and δ¹⁵N stable isotopes analyses. We provide new data on native faunas spanning different trophic levels of terrestrial, riverine, and marine environments. After establishing the basic patterns in the local isotope record, we reanalyze the available δ¹³C_col, δ¹⁵N, and δ¹³C_apa measurements from 23 individuals studied 15 years ago. That analysis reveals a relatively continuous distribution of several overlapping resources on the coast of northeastern Patagonia. Bayesian mixing models identified a combination of terrestrial and riverine resources aggregated as the main component of long-term diets. However, it generated diffuse estimations. The Bayesian ellipses, describing isotopic niches, emphasized more the spatial variations in diet between coastal and valley groups.