Humans may have been living in North America 10,000 years earlier than previously suggested, a new study has proposed.
The team from the University of Montreal in Canada analyzed artifacts from the Bluefish Caves in Yukon, which lie in an area called Beringia, a dry mass of land now mostly found underwater.
The site stretched from Yukon to Alaska over the Bering Sea leading to Russia almost 24,000 years ago during the last ice age. The new testing suggested this as the time when humans lived near the caves, setting back 10,000 years the known timing of human entry into North America via the Bering Strait.
Once confirmed, the findings on the new carbon aging tests on the ancient animal bones — first discovered in the caves in the 1970s — would place the caves as the oldest known North American archeological site, and the bones would emerge on record as the earliest proof of human settlement there.
Analyzing 36,000 Bone Fragments
Archaeologist Jacques Cinq-Mars excavated the site from 1977 to 1987, radiocarbon-dating the animal bones and hypothesizing that humans settled in the area as far back as 30,000 years ago. But it was a controversial finding as there was no direct proof that the presence of the bones in the caves represented actual human activity.
After examining about 36,000 bone fragments from the same site for two years, the University of Montreal team saw marks of human activity in 15 bones and probable traces of the same activity in about 20 others.
"We have lots of lines of evidence that are converging on what looks like quite a coherent story of what looks like human presence," said anthropologist and study author Ariane Burke, citing a series of straight, V-shaped lines on bone surfaces as made by stone tools meant for skinning animals.
Further Proof From Radiocarbon Dating
The team performed added testing via radiocarbon dating. A horse mandible, the oldest in the samples and displaying marks from a stone tool believed to have been used to remove the tongue, was radiocarbon-dated at 19,650 years and equated to 23,000 to 24,000 years ago.
Pollen found in the caves, too, was confirmed to be from the same time period.
According to Burke, certain findings in population genetics studies have demonstrated that a group of a few thousand people from Central Asia lived in Beringia — a massive region that stretched from the Northwest Territories’ Mackenzie River to Russia’s Lena River — isolated from other groups 24,000 years ago during the last ice age.
Their new results, she said, confirmed the standstill theory, which argued that the region was shut close from the rest of the continent by steppes and glaciers not conducive to humans. It was likely a place of refuge, the researcher added.
The isolation was also believed to result in their unique DNA that can still be traced in modern humans.
The findings were discussed in the journal PLoS One.
In June last year, bones of giant steppe bison and traces of their ice-age hunters have led scientists to conclude that early humans likely colonized North America south from Alaska along the Pacific coast, and not through the Rocky Mountains as previously believed.