Isotopic evidence of diet breadth hunter-gatherers changes during the Holocene in the Central Pampean Dunefields (Argentina, South America).

Abstract

Based on the analysis of stable carbon and nitrogen isotopes of bone collagen, stable carbon isotopes of bone apatite and an extensive AMS dating series (~10,000-299 years cal BP), the human paleodiets of 34 individuals from the Central Pampean Dunefields (Argentina, South America) are evaluated. These data are interpreted from the isotopic ecology of animals with archaeofaunal evidence of consumption and isotopic models of human diet. Multivariate carbon and nitrogen stable isotope model and Bayesian stable isotope ellipses were used to interpret human diets. Analysis of isotopic values indicates intake of enriched lipids and/or carbohydrates in relation to the proteins consumed throughout the Holocene. The isotopic values of Middle Holocene humans in relation to the values of exploited resources point out that individuals obtained protein mainly from guanaco. Subsequently, there was an increase in the human breadth diet during the Late Holocene, with a greater relevance of small prey of high trophic levels and vegetables. This contrasts with zooarchaeological information indicating generalist human diets during the Middle Holocene and specialized human diets in guanaco during the Late Holocene. It is proposed that during the Middle Holocene arid period, the combination of low human population density and high residential mobility in wide foraging ranges allowed the guanaco to be the main source of protein. During the Late Holocene humid period, there was an increase in human population density and a decrease in residential mobility, which caused greater pressure on foraging territories and increased dietary breadth.