Bison fossils unveil of corridor used for human and animal migrations

A research paper published in the Proceedings of the National Academy of Sciences has unveiled that by assessing bison fossils, researchers were able to shed light on early human migrations in North America.

The assessment has revealed about the opening of an ice-free corridor that opened up along the Rocky Mountains during the late Pleistocene. This corridor acted as a potential route for human and animal migrations between the far north and the rest of North America.

In the study, the researchers have put in use radiocarbon dating and DNA analysis to find out the movement of bison into the corridor. From the complete assessment, it was found that the corridor was completely open by around 13,000 years ago.

It is being suggested that the corridor might have witnessed the first movement of humans towards southward from Alaska to colonize the rest of the Americas. As per the latest evidence, the Cordilleran and Laurentide ice sheets closed the corridor much earlier.

Study’s first author Peter Heintzman from UC Santa Cruz said, “The opening of the corridor provided new opportunities for migration and the exchange of ideas between people living north and south of the ice sheets”.

Heintzman said that the radiocarbon dating has helped them to know the age about the fossils, but the key thing was genetic analysis. It has been found that the southern part of the corridor has opened first. Owing to which, southern bison started moving northward 13,400 years back.

Later, the movement of northern bison for southward started and the two populations started to overlap in the corridor by 13,000 years ago. As per the evidence, human migration within the corridor was majorly from south to north.

The study paper published in the scientific journal Eurek Alert informed…

“Scientists using evidence from bison fossils have determined when an ice-free corridor opened up along the Rocky Mountains during the late Pleistocene. The corridor has been considered a potential route for human and animal migrations between the far north (Alaska and Yukon) and the rest of North America, but when and how it was used has long been uncertain.”

In the 1970s, geological studies suggested that the corridor might have been the pathway for the first movement of humans southward from Alaska to colonize the rest of the Americas. More recent evidence, however, indicated that the Cordilleran and Laurentide ice sheets coalesced at the height of the last ice age, around 21,000 years ago, closing the corridor much earlier than any evidence of humans south of the ice sheets. The initial southward movement of people into the Americas more than 15,000 years ago now seems likely to have been via a Pacific coastal route, but the Rocky Mountains corridor has remained of interest as a potential route for later migrations.

“The radiocarbon dates told us how old the fossils were, but the key thing was the genetic analysis, because that told us when bison from the northern and southern populations were able to meet within the corridor.” The results showed that the southern part of the corridor opened first, allowing southern bison to start moving northward as early as 13,400 years ago, before the corridor fully opened. Later, there was some movement of northern bison southward, with the two populations overlapping in the corridor by 13,000 years ago.

“Bison fossils are the most widespread Quaternary mammal in western North America and of interest because they survived the extinctions at the end of the Pleistocene, unlike most other North American large mammals,” said coauthor Duane Froese of the University of Alberta. “We were able to sample bison fossils, largely from museum collections, including critical ones from central Alberta that dated to the initial opening of the corridor.”

Many of the fossils they analyzed came from collections at the Royal Alberta Museum in Edmonton and other institutions. “Thousands of steppe bison fossils are recovered in northern Canada every year,” said coauthor Grant Zazula of the Government of Yukon Palaeontology Program in Whitehorse. “Most of these fossils are uncovered by mining or gravel pit operators and later made available to scientists for study. These results speak to the importance of collecting and preserving fossils in order to better understand our history.”

According to a story published on the topic by CNN News, “Exactly when the first humans in North America left Alaska and moved south into the rest of the continent has always been subject to some debate. Scientists have long thought that humans first migrated south 15,000 years ago along a coastal Pacific path. But they always wondered about a second route, along the Rocky Mountains. People used that path for migration too, but scientists had never determined if it was trod before or after the Pacific route.”

Another reason scientists believe humans used the Pacific coast route first? The archeological evidence suggests humans mainly migrated from south to north along the Rocky Mountain route, Shapiro said, suggesting they had already established themselves south of the path — after migrating along the Pacific.

A report published in CBC News revealed, “The fossils of bison that roamed near what is now Edmonton 13,000 years ago are helping solve the mystery of the earliest humans in southern Canada, including how and when they got there and where they came from. The new analysis suggests that for bison, southern Alberta, which had previously been covered in a massive ice sheet, started becoming a nice place to live around 13,400 years ago.”

University of Alberta researcher Duane Froese, who coordinated the study, gathered about 190 bison fossils, mostly from the Royal Alberta Museum, and carbon dated them. Peter Heintzman, a postdoctoral researcher at the University of California, Santa Cruz, and the lead author of the report, conducted a DNA analysis to show which fossils came from the northern and southern populations of bison.

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