Diet composition and prey choice in prehistoric human individuals from Northwest Patagonia: An application of species distribution and isotope mixing models

Abstract

Objectives: Ancient hunter-gatherer diets were heterogeneous, varying substantially across time and space, and frequently showing considerable intrapopulation variation. The diet composition of these human groups depended primarily on resource availability, but also on the active selection of certain prey due to different bio-cultural factors. In this context, we explore resource availability, diet composition, and prey choice in the human populations of the Middle-Late Holocene from Northwest Patagonia. Material and Methods: We employ species distribution models using current and zooarchaeological data to estimate species availability throughout Northwest Patagonia, and we use Bayesian stable isotope mixing models on a large number of samples to analyze human diet composition at the individual level during the Middle-Late Holocene. Finally, we calculate a prey selectivity index to address the different dietary choices of human individuals in the region. Results: Our results show large differences in species available for consumption throughout the region, as well as a high dietary variation between human individuals, which is mainly related to their spatial location. Some species, such as guanaco, were widely distributed and consumed in the region. Notably, species of small mammals were actively selected in several areas, indicating greater importance in human diets than previously appreciated. Discussion: Species availability does not appear as the only factor driving human diets in the region, since prey choice seems to have been a recurring phenomenon among these populations. The novel approach used in this study overcomes several limitations of previous studies employing isotopic analysis in prehistoric human diets, allowing new insights into the bioarchaeology of the region.