Lineage separation· Where Sapiens lives

The founding population of the Americas separates

37.5 ka

About 36,000 years ago, a single founding population separated from the peoples of East Asia, millennia before anyone entered the Americas, and every Native American lineage sequenced descends from it.

Separation of a single founding population from the populations of East Asia, several millennia before any entry into the Americas. Every Native American lineage sequenced to date descends from it.

What the evidence shows

The estimate proceeds from a genome sequenced at seventeenfold coverage: that of an infant buried at Upward Sun River, in Alaska, some 11,500 years ago, who belongs to none of the known branches of Native American ancestry but lies below all of them. Modelling that genome against the others places the separation from East Asian populations at 36,000 years, to within 1,500, with gene flow continuing until about 25,000. The lineage then remained isolated for millennia without advancing, a situation designated by the term Beringian standstill. Ancient Beringians separated between 22,000 and 18,100 years, and the northern and southern branches from which all later Native Americans descend between 17,500 and 14,600 years.

Dating & uncertainty

Moreno-Mayar and colleagues model the separation at 36,000 years, to within 1,500, with gene flow continuing until about 25,000. Work on the Y chromosome and on mitochondrial DNA places the effective separation at 25,000 years or later. The two results are not contradictory: one dates the beginning of the separation of the lineages, the other the end of their exchanges.