Genetic Chaos

Tuesday, June 15, 2004

The Central Siberian Origin for Native American Y Chromosomes

Y chromosomal DNA polymorphisms were used to investigate Pleistocene male migrations to the American continent. In a worldwide sample of 306 men, we obtained 32 haplotypes constructed with the variation found in 30 distinct polymorphic sites. The major Y haplotype present in most Native Americans was traced back to recent ancestors common with Siberians, namely, the Kets and Altaians from the Yenissey River Basin and Altai Mountains, respectively. Going further back, the next common ancestor gave rise also to Caucasoid Y chromosomes, probably from the central Eurasian region. This study, therefore, suggests a predominantly central Siberian origin for Native American paternal lineages for those who could have migrated to the Americas during the Upper Pleistocene.

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The Dual Origin and Siberian Affinities of Native American Y Chromosomes

The Y chromosomes of 549 individuals from Siberia and the Americas were analyzed for 12 biallelic markers, which defined 15 haplogroups. The addition of four microsatellite markers increased the number of haplotypes to 111. The major Native American founding lineage, haplogroup M3, accounted for 66% of male Y chromosomes and was defined by the biallelic markers M89, M9, M45, and M3. The founder haplotype also harbored the microsatellite alleles DYS19 (10 repeats), DYS388 (11 repeats), DYS390 (11 repeats), and DYS391 (10 repeats). In Siberia, the M3 haplogroup was confined to the Chukotka peninsula, adjacent to Alaska. The second major group of Native American Y chromosomes, haplogroup M45, accounted for about one-quarter of male lineages. M45 was subdivided by the biallelic marker M173 and by the four microsatellite loci alleles into two major subdivisions: M45a, which is found throughout the Americas, and M45b, which incorporates the M173 variant and is concentrated in North and Central America. In Siberia, M45a haplotypes, including the direct ancestor of haplogroup M3, are concentrated in Middle Siberia, whereas M45b haplotypes are found in the Lower Amur River and Sea of Okhotsk regions of eastern Siberia. Among the remaining 5% of Native American Y chromosomes is haplogroup RPS4Y-T, found in North America. In Siberia, this haplogroup, along with haplogroup M45b, is concentrated in the Lower Amur River/Sea of Okhotsk region. These data suggest that Native American male lineages were derived from two major Siberian migrations. The first migration originated in southern Middle Siberia with the founding haplotype M45a (10-11-11-10). In Beringia, this gave rise to the predominant Native American lineage, M3 (10-11-11-10), which crossed into the New World. A later migration came from the Lower Amur/Sea of Okhkotsk region, bringing haplogroup RPS4Y-T and subhaplogroup M45b, with its associated M173 variant. This migration event contributed to the modern genetic pool of the Na-Dene and Amerinds of North and Central America.

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A Molecular Anthropological Perspective on the Peopling of the Americas

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Virologic and Genetic Studies Relate Amerind Origins to the Indigenous People of the Mongolia/Manchuria/Southeastern Siberia Region

A commonly held theory is that the first wave of migrants into the New World was derivative from the ethnic groups then inhabiting eastern Siberia. However, these ethnic groups lack a mtDNA haplogroup (B) that is well represented in Amerindian tribes. Also, the time depth of the other three mtDNA haplogroups found in Amerindians (A, C, and D) appears to be greater in the Amerindians than in the eastern Siberian ethnic groups. In this communication we demonstrate that the human T-cell lymphotrophic virus type II, present in 11 of the 38 Amerindian tribes thus far examined, is not present in any of the 10 ethnic groups of eastern Siberia that we have studied. However, the virus has just been reported in the indigenous population of Mongolia, and mtDNA haplogroup B is also represented in this region. On the basis of these facts, we propose that the ancestors of the first migrants to the New World were not derived from north and central Siberia but from populations to the south, inhabiting the regions of Mongolia, Manchuria, and/or the extreme southeastern tip of Siberia.

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