Site Dating 24,000 Years Ago In The Yukon

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Bones in Yukon Cave Show Humans in North America 24,000 Years Ago, Study Says Posted on January 17, 2017 —by Blake de Pastino 20614 0 A close look at bones found in a Yukon cave may confirm a controversial finding made decades ago: that humans arrived in North America 10,000 years earlier than many experts believe. Radiocarbon dating allows us to date the human presence at the site and it actually proves that people were in the Yukon as early as 24,000 BP. On why that’s significant Until now, we thought that people arrived in North America about 14,000 BP. Jan 16, 2017 The Bluefish Caves in Yukon lie in a region known as Beringia that stretched from the Mackenzie River in N.W.T. To Siberia nearly 24,000 years ago during the last ice age. Parts of it are now. Arctic ice dating to 24,000 years ago held frozen microscopic animals called rotifers. Scientists just brought them back to life.

A close look at bones found in a Yukon cave seems to confirm a controversial finding made decades ago, archaeologists say: that humans arrived in North America 10,000 years earlier than many experts believe.

The bones are the remains of horse, bison, mammoths, and other Ice Age fauna, originally excavated from the Bluefish Caves near the border of Alaska and the Yukon Territory in the 1970s and 1980s.

Back then, radiocarbon dating placed the bones at about 25, 000 years old — not in itself surprising, except that many of the bones appeared to have been butchered by humans.

And the earliest evidence of human activity on the continent — at least at the time — dated back a mere 14,000 years.

Anthropologist Lauriane Bourgeon at the University of Montreal has devoted her doctoral thesis to revisiting the controversy surrounding the Bluefish Caves bones.

And she has concluded that more than a dozen of the animal bones do indeed bear “indisputable evidence of butchery activity,” showing that humans were on the continent well before the end of the last Ice Age.

The implications of these findings are weighty, not only for the timing of the peopling of the Americas, but for the way in which people actually moved from Asia into what’s known as Eastern Beringia — the swath of North America immediately east of the Bering Strait.

“In addition to proving that Bluefish Caves is the oldest known archaeological site in North America,” Bourgeon and her colleagues write in the journal PLOS One, “the results offer archaeological support for the ‘Beringian standstill hypothesis,’ which proposes that a genetically isolated human population persisted in Beringia during the Last Glacial Maximum (ed: the Ice Age) and dispersed from there to North and South America.”

The caves were first excavated by Canadian archaeologist Jacques Cinq-Mars starting in 1977, who posited, based on radiocarbon dating at the time, that the scored and damaged animal bones were evidence of human activity in the Americas as much as 25,000 years ago.

Site Dating 24 000 Years Ago In The Yukon Region

(Learn about another contested cave discovery: “Ancient Feces From Oregon Cave Aren’t Human, Study Says, Adding to Debate on First Americans“)

Largely dismissed and later overlooked, the theory was recently taken up by Bourgeon.

Site Dating 24 000 Years Ago In The Yukon Map

In 2015, she published some of her preliminary findings, after having studied 5,600 bone fragments from Cave 2 of the Bluefish Caves.

Most of the scoring and hatching marks on the bones were made by scavenging animals and not humans, she said.

But at least two of the bones did betray the tell-tale signs of human butchery, she said, including the pelvis bone of a caribou that bore deep, parallel lines etched in them.

“That is typically the mark of a stone tool used to de-flesh or disarticulate a carcass,” she told Western Digs at the time.

But the oldest of the samples that she tested was no more than 14,000 years old.

Site dating 24,000 years ago in the yukon

(See full coverage of her 2015 study: “Butchered Bones Found in Yukon Cave Bear Marks of Early Americans, Study Finds“)

Today, she and her team have obtained even more impressive results.

Bourgeon’s full study covered 36,000 bones from Caves 1 and 2, studying them under a high-power microscope and comparing them to other bones that had been scarred by animals, broken by freeze-thaw cycles, or damaged by rockfall or other natural sources of abrasion.

Site Dating 24 000 Years Ago In The Yukon 2017

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She and her team concluded that 15 bone samples bore striations that they say are “confidently attributable to human activities.”

Unlike carnivore teeth, which leave wide, shallow, U-shaped depressions, these samples bore the signature of a hand-held tool, they assert.

“Series of straight, V-shaped lines on the surface of the bones were made by stone tools used to skin animals,” said Montreal’s Dr. Ariane Burke, adviser to Bourgeon and a co-author of the new study, in a press statement.

“These are indisputable cut-marks created by humans.”

The team also conducted its own series of radiocarbon tests on six of the bones with the butchery marks.

The youngest specimen was 12,000 years old and the oldest — the lower jaw of an extinct horse, said to have marks showing where its tongue was cut out — was 24,000 years old.

(Learn about an important discovery made, thanks to a Yukon horse: “700,000-Year-Old Horse Found in Yukon Permafrost Yields Oldest DNA Ever Decoded“)

Taken together, these two data points suggest that Ice AgeAlaska and Yukon were not only inhabited, the team asserts, but that it was inhabited by a genetically isolated population, because 24,000 years ago, the rest of the continent was covered in glaciers and impassable.

This idea — known as the Beringia standstill hypothesis — has been proposed by some geneticists, who have found molecular clues in the DNA of indigenous groups both east and west of the Bering Strait which suggest that the Americas’ earliest settlers lingered in Eastern Beringia for thousands of years before being able to migrate south.

Site Dating 24,000 Years Ago In The Yukon

(Read about a recent genetic revelation: “Genome of America’s Only Clovis Skeleton Reveals Origins of Native Americans“)

“Our discovery confirms the ‘Beringian standstill hypothesis,’” said Burke in the statement.

“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.”

A growing body of evidence has been discovered since the ‘70s that shows a substantial human presence in the Americas before 14,000 years ago.

(Like the most-read-about archaeological find of 2016: “16,000-Year-Old Tools Discovered in Texas, Among the Oldest Found in the West“)

Site Dating 24,000 Years Ago In The Yukon Ok

But there’s limited archaeological evidence to suggest that the continent was populated a full 25,000 years ago.

To that, Bourgeon and her team say, future research must focus on both archaeological and genetic evidence, specifically in the region around the Bering Strait, in order to get to the bottom of how and when the continent was populated.

“More research effort is required in Beringia clearly, to substantiate the existence of a standstill population and fully understand the prehistory of the first people of the Americas,” they write.

Bourgeon, L., Burke, A., & Higham, T. (2017). Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada PLOS ONE, 12 (1) DOI: 10.1371/journal.pone.0169486

I was taught (30 years ago) that Homo sapiens migrated to the Americas, from Asia, some 13,500 – 14,000 years ago, across the Beringian Strait. Subsequently, I became aware of an alternative to the Beringian model, whereby the influx of H sapiens was proposed from the European Atlantic sea-board, specifically, from South-West France and North-West Spain, into the Eastern sea-board of what is now the USA. This was evidenced by projectiles, tools and signs of butchered mammals dating from a much earlier time, some 25,000 – 30,000 years ago (probably during the Last Glacial Maximum). This is known as the Solutrean model, because of the similarity in knapping techniques seen in projectiles and tools found in the Americas with those of the eponymous culture in Europe. In short, not a South and East expansion from Beringia c. 14,000 years ago, but a North and West expansion from the mid-Atlantic sea-board c. 30,000 years ago.

Perhaps predictably, this latter model was debated with some heat, and generally negatively. Notwithstanding such criticism, however, and as I have noted previously, the Solutrean theory represents an important contribution to the overall debate “at least until either archaeological excavations reveal relevant assemblages, or some more genetic modelling has emerged to provide conclusive evidence for one case, or another. Or for a different story altogether.”

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And along have come those different stories. First, came a re-visit to the Bluefish Caves, in the Yukon; around 40 years ago, excavations there seemed to provide evidence for a much earlier immigration, still across the Beringian Straits, but c. 24,000 years BP, not the 14,000 years BP that the Beringian model suggested. That evidence, too, was largely rejected as too weak. Now, however, as improved dating methodology has developed, the evidence for human occupation of the site has been significantly strengthened, once again from 24,000 years BP. The proposal is that, having migrated to the Yukon, humans remained there, and did not disperse more widely across the Americas until c. 14,000 years ago. This, then, became the Beringian standstill hypothesis.

Meantime, discoveries at Monte Verde in Southern Chile, some 20 – 30 years ago, which appeared to show that humans had occupied the site 14,500 years ago, and had been largely discounted as incompatible with the Beringian model, re-surfaced just four years ago. As the Beringian model indicated that the first human occupation in the Americas was around 14,000 years ago, then even allowing for some flexibility in dating methodologies, how would it have been possible to reach Southern Chile to that timescales? Following a return to the site, archaeologists have found further evidence that shows people there had built fires, cooked plants and meat, and used tools, not 14,500 years ago, but c. 18,500 years ago. Could these dates, then, support either the Beringian standstill theory, or the Solutrean hypothesis? And why have there been no discoveries on the Western sea-board of the Americas between Beringia and Monte Verde? Are all other settlements now off-shore, with the rise in sea levels?

However, these controversies appear as nothing compared to that provoked by a recent article in Scientific American, repeated in Nature, which reports a study of remains in Southern California of an unknown human species, dated to c. 130,000 years ago. In short, before H. sapiens had left Africa! Cats and pigeons come to mind at this point.

Site Dating 24 000 Years Ago In The Yukon Valley

Critics are not hard to find, questioning the absence of any other evidence for some 110,000 years, the uncertain age of the discoveries themselves, and whether the evidence (broken mastodon bones and associated broken rocks) necessarily demonstrates human activity. Furthermore, no human presence of that antiquity has been found in North-East Asia, from where, it is still broadly assumed, even archaic humans must first have entered the Americas. I suspect that many archaeologists will be searching harder for evidence, now that they have a clearer idea of what they should be looking for. Meantime, of course, it is worth remembering once again that absence of evidence is not evidence of absence.

a) PlosOne; http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0169486
b) PlosOne; http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141923
c) Science; Nov. 2015. http://www.sciencemag.org/news/2017/05/traces-some-south-america-s-earliest-people-found-under-ancient-dirt-pyramid
d) Scientific American; https://www.scientificamerican.com/article/ancient-bones-spark-fresh-debate-over-first-humans-in-the-americas/
e) Nature; https://www.nature.com/articles/nature22065