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Home / Science / New evidence shows a 17,000-year-old coastal route to North America

New evidence shows a 17,000-year-old coastal route to North America



Photo: NASA

The first people who came to North America from Eurasia did so by traveling through the Bering Strait, according to the theory. A new theory has emerged that proposes a coastal route to the Continent, but evidence is lacking. A recent analysis of boulders, rocks and fossils in Alaska now provides a clearer picture indicating the emergence of a coastal route some 1

7,000 years ago.

New research published today in Science Advances was some of the first geological evidence of an Alaskan coastal migration route that would have allowed humans to travel from Eurasia to North America when the Ice Age was still in full swing. Importantly, the paper also contains references to aquatic and terrestrial life in the region during the same period, meaning that people have access to food. Researchers at the University of Buffalo do not say that humans have actually traveled this coastal route – they just say that the conditions for migrating people in North America were created about 17,000 years ago.

Image: Bob Wilder / U. Buffalo

At the height of the last ice age, North America was separated from Eurasia by the massive Cordillera ice sheet, which prevented people from entering the continent. After all, humans were able to do the trek, but scientists are not sure which route to take or how the transcontinental jump will take place.

During the 20th century, it was conventionally assumed that North America's first peoples traveled through a narrow, ice-free corridor, but recent evidence has thrown a fairly large blow into this longstanding hypothesis. The retreating ice sheets led to an inner path only about 14,000 years ago, and the suddenly accessible strip of land was suitable for animals and humans only about 13,000 to 12,600 years ago. This poses a major chronological problem, with archaeological findings found in Chile about 15,000 years ago and Florida about 14,500 years ago.

Hence the Coastal Migration Theory, also known as the Kelp Highway Hypothesis. Instead of traveling through an inner route, the opposite is the case, with human migrants embracing the Siberian, Bering and Alaskan coasts and eventually coming to North and South America. There is virtually no archaeological evidence to support this theory, but the recent discovery of 29 footprints on the coast of Calvert Island, British Columbia, dating back to 13,000 years, is exciting. To make matters worse, the scientists are not even sure if the glaciers have completely blocked the coastal route or when the ice cover has retreated to make the route available for human migration.

The research team traveled by helicopter to remote locations within the Alexander Archipelago in southeastern Alaska.
Photo: Jason Briner

To answer these questions, Lesnek's team visited four islands in Alaska's Alexander Archipelago miles (360 km) south of Juneau. Looking at the physical evidence, the team realized that ice once dominated the area.

"The landscape is glacial," said Jason Briner, principal author of the study and geologist at the University of Buffalo, in a statement. "The rock surfaces are smooth and scratched when the ice passes over them, and erratic boulders are everywhere. If you're a geologist, it hits you in the face, you know it right away: the glacier was here."

Using a technique Known as surface exposure dating, the researchers could find out when the egg started to retire. Chemical signatures in rocks and rocks tell scientists when ice is no longer a barrier to the elements.

"That definitely tells us that the glaciers in southeast Alaska retreated from the coast 17,000 years ago," Lesnek told Gizmodo. "We also used a rich fossil archive found in a cave on Prince of Wales Island, and by radiocarbon dating of the bones and identification of the animals from which they originated, we found that Ringed Seal and Arctic Fox lived in southeastern Alaska when the coastal route opened. "

Lesnek and her colleagues were surprised that glaciers blocked the coastal route. Her team went into this project and thought that these areas were completely ice-free during the last Ice Age. "But our results tell a different story," she said.

University of Buffalo, PhD Candidate Alia Lesnek at work on Suemez Island
Photo: Jason Briner

This paper addresses a major gap in our knowledge of how and possibly when people travel to the Americas colonized.

"We now know that glaciers could have blocked the coastal route for a few thousand years, but these glaciers retreated some 17,000 years ago, which opened the door to human migration along the coast," Lesnek said. "The timing of the glacial retreat goes very well with the genetic and archaeological evidence for the colonization of America."

It is important that the new study covers only a very small part of the coastal route and that other parts remain undated. Lesnek says her team will continue to search for areas that might have escaped glaciation and map areas where life could arise immediately thereafter.

Ben Potter, a professor of anthropology at the University of Alaska Fairbanks who was not involved in the new study, likes the new paper, saying the conclusion is plausible and that the researchers were wise to limit themselves to the idea that an early migration route along this part of the coast was possible rather than saying that this was probable or safe.

"In archaeological science, we need deliberate, methodical analysis of all aspects of paleoecology, geology, etc., to understand human adaptation and expansion, including migration," Potter told Gizmodo. "This is a welcome study to understand the complex de-icing process in this part of the Northwest Coast."

Potter said scientists should continue these species analyzes along the coast to learn more about the timing of the glacier's retreat and to track changes in the environment and ecology at this critical time. But he says the ultimate answer to the timing and nature of North American colonization is likely to be hard to find for some time.

"The migration of one or more Indian populations to America was probably a complex process, including between one and three major groups: the ancient Beringians, the Native Americans, and the Native Americans," said Potter. "The timing remains unknown, but probably 16,000 years ago, given the genetic evidence of expansion after that time."

He says the routes may have included the inner ice-free corridor, the coastal route – or more likely, both.

Recent research suggests that 15,000 years ago, ice-free proglacial lakes ruled freely [a lake in front of a melting glacier] and overcast conditions in the ice-free corridor, and this new study points to coastal livelihoods 17,000 years ago. "Studies such as these are absolutely necessary in order to properly establish hypotheses about the colonization of North America."

[Science Advances]


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