( Reuters ) - People indigenous to Siberia have strong genetic links to native peoples in the Americas, according to a study further supporting the theory that humans first entered the Americas over a land bridge across the Bering Strait.
Scientists at Stanford University in California combed through the genes of 938 people from 51 places, looking at 650,000 DNA locations in each person.
The study, in the journal Science on Thursday, revealed similarities and differences among various populations.
"This is the highest resolution look at population genetics that has been done to date, both in terms of the number of populations that have been studied and in terms of the number of (genetic) markers used," researcher Devin Absher of the Stanford Human Genome Center said in a telephone interview.
One striking finding was the genetic similarities between the Yakut people, who live in Siberia, and several native populations from Mexico, Central America, Colombia and Brazil, the researchers said. These include the Maya in Central America and the Surui and Karitiana in Brazil.
"That's really an indication of shared ancestry," Absher said.
This fits into the theory that humans migrated into the Americas from Siberia along a now-vanished land bridge across the Bering Strait between perhaps 12,000 and 30,000 years ago.
Previous research suggested a genetic link, finding that a unique genetic mutation is shared by native peoples in Siberia and the Americas, but the new findings offer deeper genetic evidence.
The scientists also were able to detect genetic differences between northern and southern Chinese populations as well as variations within the Bedouin populations of the Middle East.
"With the massive new amounts of data, we are able to tease out the subtle differences between different European populations, or between northern Chinese and southern Chinese, and that has never been possible," said Marcus Feldman, a Stanford professor of biological sciences.
The publication of the research came a day after two other important studies on human genetic variation appeared in the journal Nature. Scientists say these papers together offer strong evidence for the "Out of Africa" theory that humans originated in Africa and migrated to colonize the rest of the world in several waves.
The study showed that human populations have less genetic diversity the farther they are away from Africa.
That would be the case, the researchers said, if the people migrating out of Africa represented only a small fraction of the original African population. These migrating people would go on to establish new, less genetically diverse populations around the world, they added.