Genomic evidence for the Pleistocene and recent population history of Native Americans

Abstract

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.

Fire history on the California Channel Islands spanning human arrival in the Americas

“…13.8 ka BP) has also been suggested (e.g. [50][51][52]) and hotly debated [53][54][55][56][57]. The exact timing of human arrival in the Americas remains uncertain.…”

Mosaic evolution and the pattern of transitions in the hominin lineage

“…Molecular approaches have brought other dimensions to the discussion of baseline evolution among hominins, with debates about mutation rates [41 -43], or whether, as has been argued for modern humans, there has been a recent acceleration in the rate of change [44]. However, regardless of whether the change is constant or not, there is consensus about the cumulative nature of small-scale change at all levels in human evolution.…”

Ancient DNA and human history

“…Skoglund et al (47) analyzed a large SNP dataset that included 63 individuals from 21 present-day Native American populations and reached a conclusion similar to that of Raghavan et al (46), but one that differs somewhat. Skoglund et al (47) found that some but not all Native American populations contained a strong signal of Australo-Melanesian ancestry, especially among certain South American populations.…”

“…Instead, Native Americans received significant recent gene flow from East Asians and AustraloMelanesians, possibly via the ancestors of present-day Aleutian Islanders. Raghavan et al (46) found no evidence that any presentday Native American groups are relicts of an earlier wave of colonization. They also found no genomic evidence that fossil skulls that are morphologically similar to Australians and Melanesians were the product of an earlier wave of immigration.…”

“…They concluded that all Native Americans separated from their ancestors ∼20,000 y ago, with an upper limit of 23,000 y. Within North America, Raghavan et al (46) inferred that northern Amerindians, including Athabascans, diverged from southern North Americans and Central and South Americans ∼13,000 y ago. This divergence time is close to the earliest well-established archaeological sites in the Americas, suggesting that the separation of these lineages occurred there, and not before immigration from Asia.…”