New research suggest the first Americans came from northeast Asia during the ice age and were isolated on the Bering Land Bridge for up to 10,000 years.
This migration theory, dubbed the "Beringia Standstill," was first proposed in 2007 and later supported by DNA evidence from about 600 Native Americans, a University of Colorado at Boulder. Mutations in the DNA suggested their direct Siberian ancestors were isolated in the region for thousands of years.
"A number of supporting pieces have fallen in place during the last decade, including new evidence that central Beringia supported a shrub tundra region with some trees during the last glacial maximum and was characterized by surprisingly mild temperatures, given the high latitude," CU-Boulder researcher John Hoffecker, lead author of a short paper said in the news release.
Many researchers believe humans first entered the Americas 15,000 years ago when glaciers retreated, allowing a pathway for migration. There would have been wood in Beringia at the time, which could have been used as fuel.
"The climate on the land bridge and adjacent parts of Siberia and Alaska was a bit wetter than the interior regions like central Alaska and the Yukon, but not a lot warmer," co-author Scott Elias of Royal Holloway, University of London, said in the news release. "Our data show that woody shrubs were available on the land bridge, which would have facilitated the making of fires by the people there."
Researchers in a 2007 study found a handful of genetic mutations accumulated in Siberia before the people spread throughout the Western Hemisphere.
"The genetic record has been very clear for several years that the Native American genome must have arisen in an isolated population at least by 25,000 years ago, and the bulk of the migrants to the Americas really didn't arrive south of the ice sheets until nearly 15,000 years ago," Dennis O'Rourke of the University of Utah said in the news release. "The paleoecological data, which I think most geneticists have not been familiar with, indicate that Beringia was not a uniform environment, and there was a shrub tundra region, or refugium, that likely provided habitats conducive to continuous human habitation."
