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A groundbreaking study published in Nature on April 22, 2026, reveals that the genetic diversity of Indigenous peoples in South America was profoundly shaped by at least three major migratory dispersals. The research, co-authored by Marcos Araújo Castro e Silva, significantly expands the understanding of human evolutionary history in the Americas.
The comprehensive study, part of the Indigenous American Genomic Diversity Project, analyzed the largest genomic dataset of Indigenous Americans to date. This included 128 newly sequenced, high-coverage whole genomes from eight Latin American countries, representing 45 populations and 28 language families, combined with existing genomic data.
Researchers identified a newly recognized third migratory wave, occurring approximately 1,300 years ago, originating from Mesoamerica and extending into South America and the Caribbean. This discovery builds upon previous knowledge of two earlier dispersals: the initial peopling of the Americas from Beringia around 15,000 years ago, and a subsequent wave about 9,000 years ago that partially replaced earlier groups.
Beyond migration patterns, the study uncovered over 1 million genetic variants previously undocumented in other populations, highlighting the unique genetic richness of Indigenous genomes. Genetic signatures of natural selection were also identified, linked to adaptations in immune response, metabolism, growth, and fertility, reflecting the diverse environments of the continent.
The research also confirmed the presence of "Ypykuéra" (Australasian) ancestry, constituting about 2% of the genome in some Indigenous Americans, persisting for over 10,000 years. Additionally, 1% to 3% of the genome showed archaic hominid introgression from Neanderthals and Denisovans, contributing to adaptive traits. The study emphasized the profound genetic bottleneck caused by European colonization, which decimated Indigenous populations, yet noted remarkable genetic continuity spanning more than 9,000 years in certain regions.
