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

A groundbreaking study has uncovered a previously unknown genetic lineage in Argentina that has persisted for at least 8,500 years. Conducted by a team of DNA researchers, this investigation sheds light on the ancient inhabitants of the central Southern Cone, a region in South America that includes a significant part of Argentina. The findings, published in the journal Nature, enhance our understanding of the genetic landscape of Indigenous populations in the area.

In the central Southern Cone, which is known to be one of the last regions to be populated by humans, previous research indicated human migration into the area over 12,000 years ago. However, there has been a significant gap in genetic research pertaining to the lineages present in this region. To address this issue, the research team analyzed DNA samples from ancient individuals, spanning from approximately 10,000 years ago to as recent as 150 years ago.

Methodology and Findings

The researchers examined 344 bone and tooth samples from 310 individuals, successfully obtaining genome-wide data from 238 of these samples. By enriching ancient DNA libraries for over 1.2 million targeted single-nucleotide polymorphisms (SNPs), they compared their findings with data from 588 pre-European contact Native Americans, as well as contemporary Indigenous communities.

The study revealed a deep genetic lineage unique to central Argentina, which has coexisted with other groups while maintaining a distinct ancestry. This lineage has survived through significant climatic challenges, including periods of severe drought. The authors note, “We found that the central Argentina lineage is geographically structured along two clines, one reflecting admixture with central-Andes-like ancestry and the other with Middle Holocene Pampas-like ancestry.”

This lineage has expanded southward and interacted with other populations, showing evidence of genetic connectivity with central Andes lineages as early as 4,600 years ago. The research thus establishes a genetic framework that enhances the understanding of Indigenous population history in Argentina and the broader Southern Cone region.

Implications for Indigenous History

The persistence of this lineage suggests a remarkable continuity in the genetic makeup of the population over millennia. Although intermingling with other groups occurred, evidence indicates that many communities maintained a level of genetic homogeneity. The research highlights the possibility of a kinship-based social structure that may have influenced patterns of marriage and resource sharing in these communities.

The authors propose that the observed genetic homogeneity could be linked to the widespread adoption of the ayllu system, a social unit defined by kinship ties and cooperation. This structure likely facilitated limited gene flow among communities, leading to long periods of genetic continuity.

Future studies are essential to further illuminate the migration patterns and genetic exchanges in underrepresented regions of Argentina. By investigating a more densely sampled time series, researchers hope to clarify the dynamics of population movement and admixture in this historically rich area.

The research conducted by Javier Maravall-López and colleagues not only enriches the narrative of Argentina’s ancient populations but also sets the stage for ongoing exploration into the genetic history of Indigenous peoples in the region. As the understanding of these lineages deepens, it contributes to a more comprehensive view of human history in South America.