It was believed that the Americas were populated by humans crossing from Siberia to Alaska across a land bridge was first proposed as far back as 1590, and has been generally accepted since the 1930s. But evidence from DNA studies shows there is no direct ancestral link between the people of ancient East Asia and modern Native Americans. it was concluded that Native Americans diverged genetically from their Asian ancestors around 25,000 years ago, just as the last ice age was reaching its zenith.
According to archaeological evidence, humans did not survive the last ice age’s peak in northeastern Siberia, and yet there is no evidence they had reached Alaska or the rest of the New World till then. While there is evidence to suggest northeast Siberia was inhabited during a warm period about 30,000 years ago before the last ice age peaked, after this the archaeological record goes silent, and only returns 15,000 years ago, after the last ice age ended.
So the million dollar question is-where did the ancestors of the Native Americans go for 15,000 years, after they left rest of their Asian relatives?
As John Hoffecker, Dennis O’Rourke and argue in an article for Science, the answer seems to be that they lived on the Bering Land Bridge, the region between Siberia and Alaska that was dry land when sea levels were lower, as much of the world’s freshwater was locked up in ice, but which now lies underneath the waters of the Bering and Chukchi Seas. This theory has become increasingly supported by genetic evidence.
The Bering Land Bridge, also known as central part of Beringia, is believed to have been up to 600 miles wide. Based on evidence from sediment cores drilled into the now submerged landscape, it seems that here and in some adjacent regions of Alaska and Siberia the landscape at the height of the last glaciation 21,000 years ago was shrub tundra – as found in Arctic Alaska today.
Escape to America
The last ice age ended and the land bridge began to disappear beneath the sea, some 13,000 years ago. Global sea levels rose as the vast continental ice sheets melted, liberating billions of gallons of fresh water. As the land bridge flooded, the entire Beringian region grew more warm and moist, and the shrub tundra vegetation spread rapidly, out-competing the steppe-tundra plants that had dominated the interior lowlands of Beringia.
It triggered human migration. As retreating glaciers opened new routes into the continent, humans traveled first into the Alaskan interior and the Yukon, and ultimately south out of the Arctic region and toward the temperate regions of the Americas. The first definitive archaeological evidence we have for the presence of people beyond Beringia and interior Alaska comes from this time, about 13,000 years ago.
These people are called Paleoindians by archaeologists-direct ancestors of nearly all of the Native American tribes in both North and South America – the original “first peoples”.
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