The Bering land bridge story is one that has been taught in history classes for decades, or at least since this writer was in school in the 1960s. The only problem with the story is that it doesn’t hold water anymore.
The theory holds, according to the Guardian, that early man migrated across a land bridge in the Bering Strait between what is now Siberia and Alaska about 13,500 years ago, close to the end of the last Ice Age. These early humans were stuck there until a corridor opened up between the Eastern and Western ice sheets that covered what is now Canada.
It is believed the early humans followed the deer, buffalo and other wild animals across dry land, and this is correct. They were in the right place, but it was the wrong time, according to a new study published in Nature. The study suggests that the land bridge was inhospitable up until 12,600 years ago, almost one thousand years later than the old theory says.
This means the land bridge wasn’t open to travel until after the Clovis people had been living in North America, and 2,000 years after the earliest humans appeared in South America. This lends credence to the idea that the first humans to arrive on the continent arrived by boat or by traveling along the Pacific shore.
Following along with the new study, this means that the continent was already inhabited by early man before the Canadian ice sheets retreated enough to open a corridor for those people migrating down from the Bering land bridge.
Study was based on DNA sequencing and radiocarbon dating
Studies of ancient pollen, fossils and plant and animal DNA from lake sediments found that before 12,600 years ago, there were no grasses, trees, bison, woolly mammoths or rabbits that could serve as food and shelter along the corridor.
Eske Willerslev, a co-author of the study, and an evolutionary geneticist at the University of Copenhagen, St John’s College Cambridge and the Wellcome Sanger Institute, says “The bottom line is that, even though the physical corridor was open by 13,000 years ago, it was several hundred years before it was possible to use it.” “That means the first people entering what is now the US, Central and South America must have taken a different route. Whether you believe these people were Clovis, or someone else, they simply could not have come through the corridor, as long claimed.”
DNA sequencing tells its own story
So here is the newly revised theory, based on sequencing of surviving DNA from animal excrement, and plant tissues in the mud from Charlie Lake in British Columbia, and Spring Lake in Alberta, as well as other sites along the corridor. And the DNA sequencing really does tell us the story.
First, it is true that 12,600 years ago, the region was still inhospitable, meaning no one could survive in the corridor because there was no food or materials to make a shelter. But since evidence of prehistoric man with distinctive stone tools were found to have been living in what is now the United States 13,000 years ago, this leaves us with the question: Where did they come from?
Mikkel Winther Pederson, of the University of Copenhagen Centre for Geogenetics, and a co-author has a theory and it sounds plausible. Citing the Inuit people of the Arctic, who find their food and skins for clothing on land and in the sea, he suggests that earlier people could have used a route that took them along the coasts, along beaches, shorelines and estuaries that have long been covered up by the rising seas, reports the Christian Science Monitor.
“In caves along the coast, archaeologists have found evidence of bear and reindeer dating back 16,000 years; this suggests that the coastal route would have been open earlier for human migration,” he said. “However, as the coastlines at this time have been inundated by the sea level rise, the majority of the archaeology is now underwater.”
The study, “Postglacial viability and colonization in North America’s ice-free corridor,” was published online August 10, 2016 in the journal Nature.
