Native Americans have closer genetic ties to people in Eurasia, the Middle East and Europe than previously believed, according to new research on a 24,000-year-old human bone.
Genome sequencing on the arm bone of a 3-year-old Siberian boy known as the "Mal'ta Boy," the world's oldest known human genome, shows that Native Americans share up to one-third of their DNA with people from those regions, said Kelly Graf, a research assistant professor at the Department of Anthropology at Texas A&M University and a member of the international research team.
The team is led by researchers at the University of Copenhagen in Denmark. The study was published in the journal Nature this week.
The results add a new dimension to earlier beliefs that Native Americans were mostly descended from East Asians who crossed the land bridge from Siberia to North America some 14,000 years ago, Graf said on Thursday.
Native Americans still have genetic connections to East Asians, Graf said, but the new sequencing shows that a "significant part" of their genome, as much as 35 percent, is linked to the Middle East, Eurasia and Europe.
"The Mal'ta people who had this DNA were part of a group that ranged anywhere from Lake Baikal (Siberia) into Central Europe," she said. "This is part of a group that is genetically related to each other."
They are not genetically related to the East Asians, however, so the question remains how DNA from these two peoples both ended up in the genetic code of Native Americans. "Native American ancestry is very complicated and very complex," Graf said.
One theory, she said, is that the two distinct peoples crossed the land bridge separately and met up in North America.
"There will, hopefully, be other sites between southern Siberia and Alaska to tell us when these people were available to colonize the Americas," Graf said.
Scientists have generally believed that the clearly European features of some Native Americans derived only from their intermingling with Europeans after the 15th century.
Several tribes living in what is now the United States, most notably the Mandan tribe that is native to the Dakotas, had strikingly European-looking features, including blond hair, when they were first met by French traders in the 18th century.
That has given rise to a range of theories, both scientific and fringe, including the idea that the Welsh, Scottish or Viking explorers, or even one of the Lost Tribes of Israel, had pre-Columbian contact with Native Americans.
But Graf said the new finding shows that those "European" traits are actually native to those tribes.
"What this study is telling us is that those Europoid-looking signatures, those features, came with them over the land bridge from Siberia, and were present in people who lived in Siberia 24,000 years ago," she said.