Revealing micro-environmental subsistence diversity in the Southern Andes through organic residue analysis in pottery (Tucumán, Argentina, 200–800 CE)

The spread of agropastoralism in the South-Central Andes involved diverse local adaptations that are often difficult to detect due to poor preservation of organic remains. To address this challenge, we conducted a large-scale organic residue study of 172 Formative Period (200–800 CE) pots from three contemporaneous villages in the Tafí Valley, northwestern Argentina. Using gas chromatography–mass spectrometry (GC-MS), compound-specific isotope analysis (GC-C-IRMS), and bulk isotope analysis of charred food crusts (EA-IRMS), we reconstructed subsistence practices and local foodways across distinct micro-environments. Biomolecular and carbon-stable isotopes on lipids and charred food crusts (δ¹³C) showed the exploitation of C3 plants and ruminant animals and a clear regional patterning of broad subsistence strategies. These findings provide the first direct chemical evidence of subsistence micro-diversity within the Southern Andes, demonstrating that neighboring communities pursued distinct combinations of farming and herding despite similar cultural traditions. Methodologically, the study highlights both the potential and limitations of lipid residues for detecting plant use in South American contexts, and underscores the need for expanded regional reference datasets.