Was North America populated by a “springboard” migration across the Bering Sea? – ScienceDaily

For thousands of years during the last ice age, generations of sea migrants paddled east on skin boats through shallow ocean waters from Asia to present-day Alaska . They traveled from island to island and eventually to shore, surviving on abundant algae, fish, crustaceans, birds and game collected from coastal and coastal biomes. Their island-rich itinerary was made possible by a shifting archipelago that stretched nearly 900 miles from continent to continent.

A new study from the University of Kansas in partnership with universities in Bologna and Urbino, Italy, documents the new name of the transitional Bering Archipelago and then shows how, when and where the first Americans passed. The authors’ stepping stone hypothesis depends on the dozens of islands that emerged during the last ice age when sea levels fell when ocean waters were locked in glaciers, and then rose when the ice caps melted. The two-part study, just published in the open access journal Geoscience Reports, can answer what the writer Fen Montaigne calls “one of the greatest mysteries of our time … when humans made the first daring journey to the Americas”.

The idea of ​​“stepping stones” is based on retrospective sea level mapping while taking into account isostation – deformation of the earth’s crust due to the variation in depth and weight of ice and water, reaching its extreme at the time of the last glacial maximum about 20,500 years ago. .

“We have digitally discovered a geographic feature of considerable size that has never been properly documented in the scientific literature,” said lead author Jerome Dobson, professor emeritus of geography at KU. “We called it the Bering Transitional Archipelago; it existed about 30,000 to 8,000 years ago. When we saw it, we immediately thought, “Wow, maybe this is how the first Americans stumbled upon.” And, in fact, everything we’ve tested seems to confirm this – it seems to be true. “

For more than a decade, researchers have been pondering a mystery within a mystery. Mitochondrial DNA indicates that the migrants were isolated somewhere for up to 15,000 years on their way from Asia to North America. The Beringian arrest hypothesis stems from the fact that today Native American DNA is quite different from Asian DNA, a clear indication of a genetic drift of such magnitude that it cannot have occurred. produced only over long periods of time almost completely isolated from the Asian population. The transitional Bering Archipelago provides a suitable refuge with internal connectivity and isolation to the exterior.

Dobson said people crossing the Bering Sea likely did not have sails, but could have been experienced in paddling boats like the kayaks and umiaks that the Inuit use today.

“They probably traveled in small groups,” he said, “either from Asia or from islands off the coast of Asia. Some sailors are known to have existed 27,000 years ago in the islands in northern Japan. They were probably seafarers – not just living on the islands, but actually practicing maritime culture, economics, and travel. “

Dobson was recently awarded the Cullum Geographical Medal from the American Geographical Society (the same gold medal Neil Armstrong won for his flight to the moon and Rachel Carson for writing “Silent Spring”). He has named and continually defended “aquaterra” – all land that was repeatedly exposed and inundated during the Upper Pleistocene ice ages – thus creating an area of ​​archaeological promise scattered off all coastal regions of the globe.

Recently, Dobson and co-authors Giorgio Spada of the University of Bologna and Gaia Galassi of the University of Urbino “Carlo Bo” applied an improved model of glacial isostatic adjustment to nine global choke points, which means isthmuses and straits which have channeled transport and trade throughout history. Significant human migrations are known to have occurred through some of them, including “Beringia” – all parts of the Bering Sea that were exposed before, during and after the last ice maximum.

“These Italian ocean scientists read my article ‘Aquaterra’ and took it upon themselves to refine the limits of the aquaterra for the whole world to coarse resolution and for Beringia itself to fine resolution,” Dobson said. . “Later, we agreed to join forces and tackle these nine global choke points. At the end of this study, we suddenly spotted these islands in the Bering Sea, and it became our goal. It had immediate potential because it could be a real game. -change in terms of all the sciences understanding how migration worked in the past. We found surprising results in some other choke points and started to analyze.

In Beringia, say the three investigators, this action produced a “conveyor belt” of islands that emerged from the sea and fell, pushing bands of people east. “The first islands to appear were just off the coast of Siberia,” the KU researcher said. “Then the islands still appeared to the east. The migrants probably continued to spread east as well, usually to islands within sight and at an easy distance.

10,500 years ago, when the Bering Strait itself first appeared, almost all of the western islands were submerged. There were only three islands left and the paddling distances had increased accordingly. Thus, the occupants were forced to evacuate, and they were faced with a clear choice: return to Asia, which they knew to be populated and might even have left due to population pressure and resource constraints, or paddle to east to lesser-known territories, perhaps less populated islands. with many resources.

To fully confirm the idea spelled out in the new article, Dobson said researchers in many fields will need to collaborate like a geographer and two oceanologists did.

“We are at a point ourselves where we really need confirmation underwater,” he said. “There is no doubt that underwater archaeologists by title will prevail in this quest, but other disciplines, specialties and fields are essential. By working together and browsing the diverse literature, we presented a fundamentally new physical geography to scientists. This should prompt all relevant disciplines to question conventional theory and explore new ideas about how, when, and where people came to North America. More broadly, aquaterra can serve as a unifying theme for understanding human migrations, demic expansions, evolutionary biology, culture, settlement, and countless other topics. “

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