"The Bering corridor may have been open for much longer than previously thought," said Andrea K. Freeman, an archaeologist at the University of Calgary in Alberta, Canada. "It's possible the western end of Beringia was open as much as 30,000 years ago, while the regions bordering the Gulf of Alaska remained glaciated."
More telling has been a reappraisal of the southern coastline of Beringia.
For decades it was simply assumed that the coast of Beringia was an inhospitable place to live, said Erlandson. New evidence suggests that instead of a straight-line coast, the southern coastline of Beringia was comprised of hundreds of islands, shallow bays, and inlets. Such coastal topography would have facilitated coastal living and migration.
"This type of relatively complex coastline is much more conducive to human habitation," said Erlandson. "It provides more protected habitat. And it's much more productive, providing a wealth of resources for early settlers."
Similar shorelines around the Pacific Rim today frequently support large underwater kelp forests. Kelp forests provide habitat for sea mammals, shellfish, fish, and sea birds, providing a ready source of food. The forests also tend to break up waves heaving on shore, making for safer boating.
"The other thing that has occurred is a reappraisal of the maritime skills of early peoples," said Erlandson. "In the last several years, there has been a pretty dramatic shift about the role of the sea in human history."
Once humans moved out of Africa and into Asia and Europe, three waves of migration occurred: People traveled to Australia, Japan and the islands in western Melanesia, and to the Americas.
"We know that at least two of [these waves] occurred by boat," said Erlandson, noting that humans arrived in Australia by boat at least 50,000 years ago. "There's no reason to think the Americas couldn't have been colonized in the same way," he said.
Arguing for a Sea Route
Until now, one of the primary arguments against a coastal migration route has been the lack of archaeological evidence. "There are no sites," said Beck. "Of course, rising sea levels mean that most, if not all, of the sites would be underwater now."
Erlandson, who has written extensively on the importance of coastal habitats and the seafaring abilities of early humans, urges caution.
"We haven't proven it happened yet," he said. "There was no archaeological evidence supporting the interior route theory. It was really a leap of faith." He's also careful to add that "there's embarrassingly little data" to support arguments for a coastal route. "But that's what makes it interesting."
"The only thing that's certain is it has to be more complicated than just one group migrating across Beringia," said Beck. "It's more likely that there were numerous migrations at different times, by different routes."
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