Genetic history of the Indigenous peoples of the Americas

The genetic history of the Indigenous peoples of the Americas is divided into two distinct periods: the initial peopling of the Americas from about 20,000 to 14,000 years ago (20–14 kya), and European contact, after about 500 years ago.^[1][2] The first period of the genetic history of Indigenous Americans is the determinant factor for the number of genetic lineages, zygosity mutations, and founding haplotypes present in today's Indigenous American populations.^[3]

Indigenous American populations descend from an Ancient East Asian lineage which diverged from other East Asian peoples prior to the Last Glacial Maximum, and admixed with Ancient North Eurasians, a Paleolithic Siberian population with deep affinities to European hunter-gatherers (Western Eurasians).^[4][5][6][7] They later dispersed throughout the Americas after about 16,000 years ago (exceptions being the Na-Dene and Eskimo–Aleut speaking groups, which are derived partially from Siberian populations which entered the Americas at a later time).^[8][9]

Analyses of genetics among Indigenous American and Siberian populations have been used to argue for early isolation of founding populations on Beringia^[10] and for later, more rapid migration from Siberia through Beringia into the New World.^[11] The microsatellite diversity and distributions of the Y lineage specific to South America indicates that certain Indigenous American populations have been isolated since the initial peopling of the region.^[12] The Na-Dene, Inuit and Native Alaskan populations exhibit Haplogroup Q-M242; however, they are distinct from other Indigenous Americans with various mtDNA and atDNA mutations.^[13][14][15] This suggests that the peoples who first settled in the northern extremes of North America and Greenland derived from later migrant populations than those who penetrated farther south in the Americas.^[16][17] Linguists and biologists have reached a similar conclusion based on analysis of Indigenous American language groups and ABO blood group system distributions.^{[18][19][20][21]}