Until now, it was believed that the earliest settlement date of North America was 14,000 years ago. This figure has now been demonstrated to have been 10,000 years earlier. The first entry of humans into North America across the Bering Strait is now estimated at 24,000 Before Present (BP), and happened at the height of the last ice age or Last Glacial Maximum. This estimate has been made according to the earliest dated archaeological sites.
Ariane Burke, a professor in Université de Montréal’s Department of Anthropology, and her doctoral student Lauriane Bourgeon, with the contribution of Dr. Thomas Higham, Deputy Director of Oxford University’s Radiocarbon Accelerator Unit, has demonstrated this beyond any doubt.
Archaeologist Jacques Cinq-Mars excavated the Bluefish Caves, located on the banks of the Bluefish River in northern Yukon near the Alaska border, between 1977 and 1987. Artifacts from these caves were used by the researchers to make their discovery. They made the hypothesis that human settlement in the region dated as far back as 30,000 BP based on radiocarbon dating of animal bones.
Cinq-Mars’ hypothesis remained highly controversial in the scientific community as there are no other sites of similar age. There was also no evidence that human activity resulted in the presence of bison, mammoth, horse and caribou bones in the Bluefish Caves.
To obtain accurate data, Bourgeon examined approximately 36,000 bone fragments that had been removed from the site and preserved at the Canadian Museum of History in Gatineau. This was a huge undertaking and it took her two years to complete. Undeniable traces of human activity in 15 of the bones was revealed by a comprehensive analysis of certain pieces at the Ecomorphology and Paleoanthropology Laboratory of UdeM. Approximately 20 other fragments also showed traces that probably resulted from the same type of activity.
Burke notes that a series of straight, V-shaped lines found on the surface of the bones were made by stone tools when animals were skinned. She added that the cut marks were indisputably created by humans.
The bones were submitted for further radiocarbon dating by Bourgeon. A horse mandible, which was identified as the oldest fragment, showed the marks of a stone tool that was probably used to remove the tongue. This piece was radiocarbon dated at 19,650 years, which is equivalent to between 23,000 and 24,000 calibrated years Before Present.
Burke explained that this discovery shows that this is the earliest known site of human settlement in Canada and confirms the previous analyses. It also demonstrates that Eastern Beringia was settled during the last ice age.
Beringia stretches from the Lena River in Russia to the Mackenzie River in the Northwest Territories. As such, it is a vast region. Burke notes that studies in population genetics have shown that 15,000 to 24,000 years ago, a group of a couple of thousand individuals lived in Beringia, isolated from the rest of the world.
She added that their discovery confirms the ‘Beringian standstill [or genetic isolation] hypothesis’, as geographical isolation would have corresponded to genetic isolation. Beringia was possibly a place of refuge as, during the Last Glacial Maximum, it was isolated from the rest of North America by steppes and glaciers too inhospitable for human occupation to the West.
At the end of the last ice age, the Beringians of Bluefish Caves were probably among the ancestors of people who colonized the whole continent along the coast, up to South America.
The full study was published in the journal PLOS One.