Migration into the continents

The specifics of Paleo-Indian migration to and throughout the Americas, including the exact dates and routes traveled, are subject to ongoing research and discussion.[1] The traditional theory has been that these early migrants moved into the Beringia land bridge between eastern Siberia and present-day Alaska around 40,000 – 17,000 years ago, when sea levels were significantly lowered due to the Quaternary glaciation.[1][2] These people are believed to have followed herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets.[3] Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific Northwest coast to South America.[4] Evidence of the latter would since have been covered by a sea level rise of a hundred meters following the last ice age.[5]

Archaeologists contend that the Paleo-Indian migration out of Beringia (eastern Alaska), ranges from 40,000 to around 16,500 years ago.[6][7][8] This time range is a hot source of debate. The few agreements achieved to date are the origin from Central Asia, with widespread habitation of the Americas during the end of the last glacial period, or more specifically what is known as the late glacial maximum, around 16,000 – 13,000 years before present.[8][9]

The American Journal of Human Genetics released an article in 2007 stating "Here we show, by using 86 complete mitochondrial genomes, that all Indigenous American haplogroups, including Haplogroup X (mtDNA), were part of a single founding population."[10] Amerindian groups in the Bering Strait region exhibit perhaps the strongest DNA or mitochondrial DNA relations to Siberian peoples. The genetic diversity of Amerindian indigenous groups increase with distance from the assumed entry point into the Americas.[11][12] Certain genetic diversity patterns from West to East suggest, particularly in South America, that migration proceeded first down the west coast, and then proceeded eastward.[13] Geneticists have variously estimated that peoples of Asia and the Americas were part of the same population from 42,000 to 21,000 years ago.[14]

New studies shed light on the founding population of indigenous Americans, suggesting that their ancestry traced to both east Asian and western Eurasians who migrated to North American directly from Siberia. A 2013 study in the journal Nature reported that DNA found in the 24,000 year old remains of a young Boy in Mal’ta Siberia suggest that up to one-third of the indigenous Americans may have ancestry that can be traced back to western Eurasians, who may have "had a more north-easterly distribution 24,000 years ago than commonly thought"[15] Professor Kelly Graf said that "Our findings are significant at two levels. First, it shows that Upper Paleolithic Siberians came from a cosmopolitan population of early modern humans that spread out of Africa to Europe and Central and South Asia. Second, Paleoindian skeletons with phenotypic traits atypical of modern-day Native Americans can be explained as having a direct historical connection to Upper Paleolithic Siberia." A route through Beringia is seen as more likely than the Solutrean hypothesis.[16]

The Clovis culture (sometimes referred to as the Llano culture[17]) is a prehistoric Paleo-Indian culture, named after distinct stone tools that were found at sites near Clovis, New Mexico, in the 1920s and 1930s. The Clovis culture appears around 11,500 RCYBP (radiocarbon years before present[18]), at the end of the last glacial period, characterized by the manufacture of "Clovis points" and distinctive bone and ivory tools. Archaeologists' most precise determinations at present suggest that this radiocarbon age is equal to roughly 13,500 to 13,000 calendar years ago.