Pica 8: Refining dietary reconstruction through amino acid δ13C analysis of tendon collagen and hair keratin

Abstract

Stable isotope analysis of archaeological human remains is routinely applied to explore dietary habits and mobility patterns. The isotope information pertaining to the period prior to death may help in identifying locals and non-locals, especially when investigating individuals from the same funerary context but believed to have been highly mobile across the landscape.Based on the variety of the funerary goods in graves and what it is believed their diets comprised, it is thought that both local and non-local individuals were buried at the inland funerary site of Pica 8 (northern Chile, Late Intermediate Period, ∼1050–500 BP); however, uncertainties over the dietary intakes and mobility histories of these individuals still persist. The aim of this study is to refine the dietary characterization of a subset of Pica 8 individuals by increasing the temporal resolution of their dietary reconstructions, specifically throughout the last period of their life, and by identifying the multiple sources of food in their overall diets. This is achieved by analysing the amino acid carbon isotope composition of hair keratin and, for the first time, that of tendon collagen.This study proposes a new method for identifying the predominant food source (terrestrial or marine) in a mixed diet using phenylalanine, valine and leucine δ13C values measured in collagenous tissues. Herein, tendon is proven to be an ideal tissue for isotopically characterising the final year of an individual's life. Our results show that individuals previously identified as non-locals, based on long-term food consumption, had in reality abandoned their original dietary habits typical of distant regions many months before death, and hence had presumably relocated to the locality of Pica.