A groundbreaking interdisciplinary study has unveiled the dramatic 2,000-year history of a population living at the southern edge of the ancient Andean farming frontier. By analyzing ancient DNA from Argentina's Uspallata Valley, researchers discovered that local hunter-gatherers adopted agriculture themselves, rather than being replaced by incoming farmers. However, this transition eventually pushed the society to the brink of collapse, revealing a harrowing tale of climate instability, malnutrition, and disease that forced communities to rely on deep family networks for survival.
The findings, published in the journal Nature, offer unprecedented insights into how agriculture reshaped human societies and how ancient people navigated prolonged periods of hardship. The research team, led by the Microbial Paleogenomics Unit at Institut Pasteur, combined ancient human and pathogen genomics with isotopic data, archaeology, and paleoclimate records, working closely with modern Huarpe Indigenous communities.
- As Farming Developed, So Did Cooperation – And Violence
- Ancient Andean Agricultural Innovation Rewrites 'Scarcity Mindset'
The Local Adoption of Agriculture
One of the most debated questions in archaeology is whether the spread of agriculture was driven by migrating farmers or by local hunter-gatherers adopting new crops and techniques. The Uspallata Valley provided a unique opportunity to explore this, as farming arrived there much later than in other parts of South America.
The team analyzed genome-wide ancient DNA from 46 individuals, spanning from early hunter-gatherers living around 2,200 years ago to later farming populations. The results were clear: there was strong genetic continuity over more than a millennium. This indicates that the local populations themselves gradually incorporated maize and other crops into their diets, rather than being overtaken by a massive influx of agricultural migrants.
"Beyond the local story of Uspallata, we are also filling a gap in South American human genetic diversity by documenting a genetic component that was previously only suggested by analysing present-day populations," explained Pierre Luisi, co-first author of the study and a researcher at CONICET in Argentina. He noted that this ancestral genetic component persists in modern populations, arguing against narratives that indigenous descendants in the region went extinct.
- New Research Shows Maya Civilization Could Have Survived Droughts
- What Ancient Farmers Teach Us About Adapting to Climate Change
Landscape on the Andes near Upsallata, Argentina. (R3silva/CC BY-SA 4.0)
A Crisis of Climate, Diet, and Disease
While the initial adoption of farming was flexible, a stark shift occurred between 800 and 600 years ago at a major burial site known as Potrero Las Colonias. Isotope analysis of bones and teeth revealed that individuals here relied heavily on maize - showing some of the highest consumption levels in the southern Andes. Furthermore, strontium isotopes indicated that these people were migrants who had moved into the valley from nearby regions.
Despite their close genetic relationship to the local groups, this migrant farming community faced a severe and sustained population decline. Paleoclimate records point to extended periods of environmental instability during this time. The skeletal remains bore the physical markers of this crisis, showing clear signs of childhood malnutrition and widespread infection.
Most shockingly, the ancient DNA analysis detected the presence of tuberculosis at the site. The strain belonged to a lineage known from pre-contact South America, but finding it this far south was entirely unexpected. "Detecting tuberculosis this far south in a pre-contact context is striking," stated Nicolás Rascovan, head of the Microbial Paleogenomics Unit. This discovery raises profound questions about how the disease spread and persisted in the challenging ecological conditions of the ancient Andes.
Family Networks as a Survival Strategy
Faced with overlapping pressures of climate change, food shortages, and infectious diseases, the community turned to their most fundamental resource: family. Genomic kinship analysis revealed that many of the migrants buried at the site were closely related, but they were interred at different times. This suggests an ongoing, multi-generational migration into the valley.
Interestingly, these kinship networks were primarily organized through maternal lines, with a single mitochondrial lineage dominating among the migrants. This highlights the crucial role women played in maintaining family continuity and coordinating movement during times of crisis. There was no evidence of violent conflict, and locals and newcomers were sometimes buried together, indicating a peaceful coexistence.
"No farming community abandons fields and homes lightly," noted archaeologist and co-first author Ramiro Barberena. "Our results are most consistent with people moving under force majeure, relying on family networks to navigate crisis." This ancient strategy of kinship-based resilience offers a poignant perspective on how human societies adapt to environmental and demographic pressures, a lesson that remains highly relevant today.
Top image: Illustration representing population movements within the Southern Andes as a resilience strategy to face crises. Source: Mauricio Álvarez - studio FIEL®
By Gary Manners
References
Barberena, R. et al. 2026. Local agricultural transition, crisis and migration in the Southern Andes. Nature. Available at: https://www.nature.com/articles/s41586-026-10233-z
Institut Pasteur. 2026. Integrative archaeogenetics reveal how Southern Andean communities adopted farming and endured crises. EurekAlert. Available at: https://www.eurekalert.org/news-releases/1120037
