Ancient DNA Reveals 8,500-Year-Old Lineage in Argentina

A recent study has unveiled a previously unknown genetic lineage in central Argentina that has persisted for at least 8,500 years. Published in the journal Nature, this research sheds light on the population history of the central Southern Cone, an area that has long been underrepresented in genetic studies. Scientists examined ancient DNA from individuals who lived between 10,000 and 150 years ago, revealing significant insights into the region’s early inhabitants.

Uncovering Genetic Continuity

The central Southern Cone, encompassing parts of Argentina, has been recognized as one of the last regions globally to be settled by humans. Despite indications of migration into the area over 12,000 years ago, comprehensive genetic research on local lineages has been sparse. A team led by researcher Javier Maravall-López screened 344 bone and tooth samples from 310 individuals, successfully obtaining genome-wide data from 238 of them. The study focused on the genetic diversity of the region, which had previously been overlooked.

The researchers enriched ancient DNA libraries for over 1.2 million targeted single-nucleotide polymorphisms (SNPs). They compared this new data with existing genetic material from 588 pre-European contact Indigenous Americans, as well as data from contemporary Native Americans. By employing rigorous statistical methods, they assessed population structures, intergroup mixing, and community sizes.

A Deep Lineage Emerges

One of the study’s most significant findings was the identification of a deep genetic lineage that has existed in central Argentina for the last 8,500 years. This lineage remains present in modern Argentine populations, indicating its survival despite climatic challenges, including severe droughts. The analysis revealed that this lineage is geographically structured along two main clines: one associated with central-Andes-like ancestry and another reflecting ancestry from the Middle Holocene Pampas.

The research indicates that this lineage coexisted with others and became the predominant ancestry in the Pampas region after 800 years ago. Furthermore, genetic connections with the central Andes lineage were evident as early as 4,600 years ago, suggesting a complex web of interactions among ancient populations.

While intermingling with other groups occurred, the study highlights evidence of a largely isolated genetic structure. This isolation may be attributed to kinship-based social systems, which have historically influenced marriage patterns and community dynamics in the region. The authors note increased close-kin unions in northwest Argentina, paralleling similar practices in the central Andes.

The study’s findings emphasize the need for further research to explore the genetic and cultural history of Argentina’s Indigenous populations. As more densely sampled time series become available, future studies could clarify migration patterns and intergroup interactions, enriching our understanding of this historically significant region.

The research conducted by Javier Maravall-López and colleagues provides a vital genetic framework for understanding the Indigenous population history of Argentina and the Southern Cone. It highlights the importance of ancient DNA studies in uncovering the intricate narratives of human history that have shaped modern populations.