Until now, the earliest dated archaeological sites put the first settlement of North America at around 14,000 years ago, but a fresh look at evidence from Bluefish Caves now puts that back to 24,000 years – at the height of the last Ice Age.
The evidence includes the lower jaw of a horse, whose carcass shows signs of having been butchered by humans attempting to cut out its tongue.
Located on the banks of the Bluefish River in northern Yukon near the Alaska border, the site was excavated by archaeologist Jacques Cinq-Mars between 1977 and 1987. Based on radiocarbon dating of animal bones, he made the bold claim that human settlement in the region dated as far back as 30,000 years.
In the absence of other sites of similar age, Cinq-Mars’ hypothesis has remained highly controversial, especially given that there was no evidence these animal bones had anything to do with humans.
Now, Ariane Burke and Lauriane Bourgeon at the Université de Montréal’s Department of Anthropology re-examined over 36,000 bone fragments recovered from the site. Among them, they found 15 bearing ‘undeniable traces of human activity’, and another 20 fragments with ‘probable’ traces of the same type of activity.
The forensic examination of cutmarks made by humans, versus those made by animals, or other natural causes is a pretty well-established field of study, and these days archaeologists are pretty confident at being able to tell the difference. A close-up look at the profile of a cutmark can indicate what kind of tool was used, the kind of action applied and even the material it was made from.
According to Burke, they found “indisputable” evidence of cut-marks created by humans, including a “series of straight, V-shaped lines on the surface of the bones… made by stone tools used to skin animals”.
Having confidently identified human-made cut-marks, Bourgeon submitted the bones to Dr. Thomas Higham, Deputy Director of Oxford University’s Radiocarbon Accelerator Unit, for further radiocarbon dating.
The results showed that the oldest fragment was a horse mandible bearing the marks of a stone tool on its inner surface, which had apparently been used to remove the tongue. It was radiocarbon-dated to between 23,000 and 24,000 cal BP (calibrated years Before Present).
Beringia is a vast region stretching from the Mackenzie River in the Northwest Territories to the Lena River in Russia. During the Last Glacial Maximum, Beringia was isolated from the rest of North America by glaciers and steppes too inhospitable for human occupation to the West, and was potentially a place of refuge.
According to Burke, their findings back up the studies of population genetics which have shown that a group of a few thousand individuals lived in isolation from the rest of the world in Beringia between 15,000 and 24,000 years ago, and that the Beringians of Bluefish Caves may have been among the ancestors of people who, at the end of the last Ice Age, colonized the entire continent along the coast to South America, she said in a statement.
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