DNA evidence plus sediment cores from Alaska and the Bering Sea suggest that humans inhabited the Beringian land bridge for up to 10,000 years before heading into the New World, according to a new study.
Previous genetic studies suggest that the DNA of modern Native Americans diverged from their Asian ancestors around 25,000 years ago. However, the earliest undisputed archaeological evidence of human settlement in the Americas only dates back to around 15,000 years ago, after the massive ice sheets blocking Alaska and Canada had retreated.
It was previously thought that the 3,000-mile by 1,000-mile Beringian land bridge was a treeless tundra steppe incapable of supporting a large human population, but the sediment cores now suggest that the landscape was actually dotted with oases of brushy shrubs and trees such as spruce, birch, willow, and alder. These woodland havens could have provided fuel for fire, raw material for shelters, and refuge for game such as hares, birds, elk, and moose.
The main argument against the long-term Beringian refuge hypothesis is the fact that no archaeological evidence of human settlement there has ever been found. But, according to anthropological geneticist Dennis O’Rourke of the University of Utah, this is not surprising – it was drowned by the rapid sea level rises caused by the melting ice sheets. He said:
“The evidence we have to date suggests that the refugia were distributed primarily in the lowland area of the Beringia landmass. The archaeological record that we expected to see isn’t there because the places where people were living are now under water.”
It may just lie on the sea bed, waiting to be found.
Source: National Geographic