A new study in Nature examines over 2,000 years of population history in Argentina's Uspallata Valley, showing local hunter-gatherers adopted farming rather than it being introduced by migrants. Later, maize-dependent groups from nearby areas migrated into the region amid climate instability, disease, and population decline. Kinship networks helped communities endure without evidence of violence.
Researchers from the Microbial Paleogenomics Unit at Institut Pasteur analyzed genome-wide ancient DNA from 46 individuals in Argentina's Uspallata Valley, spanning early hunter-gatherers around 2,200 years ago to later farming populations. The study, published in Nature, reveals strong genetic continuity, indicating that local hunter-gatherers adopted maize and other crops rather than large incoming groups introducing farming techniques, which arrived later in this southern Andean region compared to elsewhere in South America. Stable isotope analysis of bones and teeth showed flexible diets initially, but between 800 and 600 years ago at the Potrero Las Colonias site, individuals relied heavily on maize—the highest levels in the southern Andes—and displayed non-local strontium signatures, suggesting migration from nearby regions within the same genetic network. Genomic data indicate a sharp, long-term population decline during this period, coinciding with paleoclimate records of environmental instability. Skeletal evidence points to childhood malnutrition and disease, including tuberculosis from a pre-contact South American lineage, detected farther south than previously known. Ancient DNA also highlights multi-generational family ties, often through maternal lines, with related individuals buried at different times, implying coordinated movement. No signs of violence appear, and locals and newcomers were sometimes interred together, pointing to peaceful coexistence. Pierre Luisi, co-first author from CONICET, noted the persistence of an ancestral genetic component, countering narratives of indigenous extinction post-Argentine state formation. Nicolás Rascovan, head of the unit, highlighted the tuberculosis finding's implications for pathogen spread. Ramiro Barberena, archaeologist and co-first author from CONICET, described the migration as driven by force majeure, with family networks aiding survival. The research involved Huarpe Indigenous communities, with three members as co-authors, ensuring collaborative interpretation.