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article imageYukon caves yield evidence of earliest humans in North America

By Karen Graham     Jan 16, 2017 in Science
On a limestone ridge, overlooking the upper Bluefish River in Yukon, Canada, are three small caves. Buried in the cave deposits are the bones of long-gone animals, some with marks made by stone tools wielded by possibly North America's earliest humans.
The Bluefish Caves contain some of the oldest, undisturbed archaeological evidence in Canada that points to the earliest traces of human migration across the Beringia land mass.
The Bluefish Caves lie in a region that was part of the dry land mass that is now mostly underwater. Beringia stretched from the Yukon and Alaska, over the Bering Sea to Russia during the last Ice Age almost 24,000 years ago. Excavations of the caves by archaeologists from 1977 to 1987 produced some large animal bones with butchering marks that may have been made with stone tools.
Canadian Museum of History
The bones in question were radiocarbon dated, and the dating lead archaeologists to propose that the first migration of human groups into Eastern Beringia (Alaska and the Yukon Territory) occurred during the last Ice Age or LGM (Last Glacial Maximum). This conclusion led to great controversy in the archaeological community, primarily because there was no evidence of similar sites in the region.
And there were also concerns over the striations and anthropogenic signature on the bone evidence that yielded the dates. The bulk of archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present), well after the LGM, according to researchers at the University of Montreal.
After using new Accelerator Mass Spectrometry (AMS) radiocarbon dates obtained on the cut-marked bone samples tested earlier, the results gave credence to the hypothesis that "that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP)."
This horse mandible from Cave 2 shows a number of cut marks on the lingual surface. They indicate th...
This horse mandible from Cave 2 shows a number of cut marks on the lingual surface. They indicate that the animal's tongue was cut out with a stone tool.
University of Montreal
In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the findings also lend archaeological support for the “Beringian standstill hypothesis” that suggests that isolated groups of humans remained in LGM Beringia and only dispersed into North and South America after the post-LGM period.
"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 Ariane Burke, an anthropologist at the University of Montreal told CBC Canada.
She went on to explain what researchers look for when examining bone fragments with cuts and striations on them. "You look at the shape the tool makes when it cuts into the bone," she said. "A stone tool will typically leave a 'V' shaped mark that is straight with streaks on the walls of the cut mark."
A caribou bone. The specimen (# I5.6.5) is dated to 18 570 ± 110 14C BP (OxA-33777) and shows strai...
A caribou bone. The specimen (# I5.6.5) is dated to 18,570 ± 110 14C BP (OxA-33777) and shows straight and parallel marks resulting from filleting activity.
University of Montreal
Burke also said that pollen found in the caves was dated to 24,000 years ago. But besides determining the age of the bones, the Montreal researchers also examined in more detail the “Beringian standstill hypothesis." Burke says the theory of an isolated group staying in the Beringia region during the last Ice Age would cause the DNA of those survivors to be very unique, with that type of DNA being traced to humans today.
The big takeaway from this research is the credibility of the bone dating. And while some scientists will still look at the study with raised eyebrows, the work does add to other studies on the migration of humans into North America before 14,000 years ago.
Digital Journal reported on a study in September 2016 that showed evidence that supports the growing belief that early humans, predating the Clovis people made it to the Americas over 14,000 years ago.
More about bluefish caves, yukon Canada, clovisfirst theory, contradiction, 10000 years earlier
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