Looking for criteria to define groups and select resources for mixing models in northwest Patagonia. Comments on the paper by Gil et al. (JAS Reports 2020, 34, 102620)

Abstract

Referring to an article recently published by JAS Reports (Gil et al., 2020a, 34, 102620) this comment raises some questions about the use of vegetation units to group human samples and the selection of resources included in a mixing model of diet composition in Northwest Patagonia. We analyzed the same dataset of human δ13C and δ15N isotopes but grouping the samples by environmental and archaeological similarity and using resources well supported by archaeological evidence. In contrast to Gil et al. (2020a), we found large diet differences among areas within Northwest Patagonia, with the sample from North Neuqu´en displaying lower variation in isotopic values and lower diversity in the resources consumed compared to neighboring areas. This pattern is hidden by the approach followed by Gil et al. (2020a), biasing our understanding of diet variation in the region. These results caution against grouping human samples in extensive vegetation units and the use of a large number of resources.