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The first migrants to the Americas were descendants of the human species that arose in Africa and were part of the dispersal of modern humans around the planet, according to a new study published in the journal Evolutionary Anthropology.

"We have always assumed that the initial peopling of the Western Hemisphere was a single, unique and independent event," Dennis O'Rourke, a professor of anthropology and Kansas University, said in a news release. "By seeing it as part of a larger global process, everything we learn about other dispersals into geographic areas out of Africa within the last 50,000 years or so are relevant to our understanding of the American case."

The great migration unification

Up to now, settlement of the Americas appeared to be mostly separate from the out-of-Africa dispersal that started around 50,000 years ago. The earliest Americans were thought to be descended from a small subset of Eurasians that moved to North America fewer than 15,000 years ago.

However, archaeological findings since 2000 have revealed that Homo sapiens occupied the land bridge between Asia and North America, known as Beringia, prior to 30,000 years ago and during what is referred to as the Last Glacial Maximum (LGM), the last time ice sheets were at their largest.

"Linking the process of peopling near the time of the LGM brings the idea of 'refugia,' which we see for populations elsewhere at this time, into sharper focus as a possible mechanism for source populations in the Americas and the role that may play in structuring the genetic variation we see early in the record," O'Rourke said about the study.

The "Beringian Standstill Hypothesis," is founded on the evaluation of mitochondrial DNA in specimens from living Native American and Siberian people. The DNA evidence and historical climate research indicated the isolated residents of Beringia migrated at the conclusion of the LGM to stay away from rising sea levels.

O'Rourke said the research pointed to many questions around the complicated migration of people across Beringia. He said future studies should look for high-quality ancient DNA information from northeast Siberia from 15,000 to 30,000 years ago.

"Augmenting the paleoecological record across the Bering Sea basin, and expanding the archaeological record around the western and southwestern coasts of Alaska, would be quite useful," he said.