The earliest settlement date of North America, previously estimated at 14,000 years BP, is now estimated at 24,000 BP, at the height of the last ice age.
     University of Montreal Department of Anthropology researchers made their discovery using artefacts excavated between 1977 and 1987 from the Bluefish Caves, Canada, on the banks of the Bluefish River in northern Yukon near the border with Alaska. Their bold hypothesis is based on radiocarbon dating of animal bones.
     Doctoral student Lauriane Bourgeon spent two years examining approximately 36,000 bone fragments culled from the site, revealing undeniable traces of human activity in 15 bones and probable traces in 20 other fragments. The oldest fragment - a horse jawbone showing the marks of a stone tool apparently used to remove the tongue - was radiocarbon dated to between 23,000 and 24,000 years BP.
     Professor Ariane Burke explains that: "Series of straight, V-shaped lines on the surface of the bones were made by stone tools used to skin animals. These are indisputable cut-marks created by humans. Our discovery confirms previous analyses and demonstrates that this is the earliest known site of human settlement in Canada. It shows that Eastern Beringia was inhabited during the last ice age."
     Beringia is a vast region stretching from the Mackenzie River in Canada's Northwest Territories to the Lena River in Russia. Studies in population genetics have shown that a group of a few thousand individuals lived in isolation from the rest of the world in Beringia 15,000 to 24,000 years ago.
     Professor Burke adds: "Our discovery confirms the 'Beringian standstill hypothesis'. Genetic isolation would have corresponded to geographical isolation. 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. It was potentially a place of refuge."
     The Beringians of Bluefish Caves were therefore among the ancestors of people who, at the end of the last ice age, colonised the entire continent along the coast to South America.

Edited from Phys.org (16 January 2017)