The Bering Land Bridge Wasn't Just A Highway To Americas; People Lived There For Millennia
The Bering Land Bridge — an ancient, long-submerged steppe connecting Alaska and Russia — is often thought of as little more than a passageway from Asia for the first Americans. But a new argument, based on an analysis of sediment cores in the Bering Strait and Alaska, may change that conception.
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Published Friday in the journal Science, the research suggests humans may have inhabited the area known as Beringia for as many as 10,000 years. This picture of permanent Beringians reconciles some puzzling dissimilarities in the DNA record of Native Americans and Asians. But it also creates its own set of problems, mainly: if so many people lived there for so long, why haven't we found any of their stuff?
"We're putting it together with the archaeology and genetics that speak to American origins and saying, look, there was an environment with trees and shrubs that was very different than the open, grassy steppe. It was an area where people could have had resources, lived and persisted through the last glacial maximum in Beringia," lead author Dennis O'Rourke, an anthropologist at the University of Utah, said in a news release.
Beringia was a 1,000-miles-wide strip that lasted until the end of the last ice age 18,000 years ago and became submerged as melting glaciers caused sea levels to rise. About 6,000 years ago, the coastlines of Alaska and Russia arrived at their current locations; the water in between is called the Bering Strait.
Just what kind of landscape existed there before is the matter at hand for O'Rourke and his two colleagues. Previously, paleoecologists believed Beringia to be a vast wasteland with hardly a shrub to offer shelter, fuel, fire, or food. But ever since scientists compared the genetic sequences of modern Asians and Native Americans, there has been a problem. The DNA is too different to have morphed from one form to the other without some middle transition.
Now, recently drilled sediment cores tell a different story of the landscape, according to O'Rourke. The samples contained the pollen of trees and shrubs, suggesting "a patchwork of environments, including substantial areas of lowland shrub tundra," he says. These patches of refuge could have been the home base for a civilization that lasted from 25,000 years ago to 15,000 years ago.
The numbers are important. Evidence suggests the first Asians descended into North America 15,000 years ago; meanwhile, genetecists believe it would have taken 10,000 years for an isolated population to become genetically distinct. O'Rourke says bison, mammoths, birds, and moose probably lived within range of hunters. "They probably hunkered down pretty good in the winter, though. It would have been cold," he says.
There's still a problem with this idea. If people were living in the place for 10,000 years, there ought to be some record of their existence: a tool, a dwelling, a fossil, something. To date, not a single piece of hard evidence has been recovered. O'Rourke says he needs that to prove his theory, but suggests that because these Beringians probably lived in lowlands, their remains are probably at the bottom of the Bering Strait. A Beringia scholar not connected with this research told National Geographic: "I'd love to see some archaeological data coming from submerged, or nearly submerged, Beringian sites that would give us a clue if humans did inhabit this area."
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