The timing of
the first entry of humans into North America across the Bering Strait
has now been set back 10,000 years.
horse mandible from Cave 2 shows a number of cut marks
on the lingual surface. They indicate that the animals
tongue was cut out with a stone tool. Image-University
This has been demonstrated beyond a shadow of a
doubt by Ariane Burke, a professor in Université de Montréals
Department of Anthropology, and her doctoral student Lauriane Bourgeon,
with the contribution of Dr. Thomas Higham, Deputy Director of Oxford
Universitys Radiocarbon Accelerator Unit.
Their findings were published in early January in the open-access
journal PLoS One.
The earliest settlement date of North America, until now estimated
at 14,000 years Before Present (BP) according to the earliest dated
archaeological sites, is now estimated at 24,000 BP, at the height
of the last ice age or Last Glacial Maximum.
The researchers made their discovery using artifacts from the
Bluefish Caves, located on the banks of the Bluefish River in northern
Yukon near the Alaska border. The site was excavated by archaeologist
Jacques Cinq-Mars between 1977 and 1987. Based on radiocarbon dating
of animal bones, the researcher made the bold hypothesis that human
settlement in the region dated as far back as 30,000 BP.
In the absence of other sites of similar age, Cinq-Mars
hypothesis remained highly controversial in the scientific community.
Moreover, there was no evidence that the presence of horse, mammoth,
bison and caribou bones in the Bluefish Caves was due to human activity.
To set the record straight, Bourgeon examined the approximate
36,000 bone fragments culled from the site and preserved at the
Canadian Museum of History in Gatineau an enormous undertaking
that took her two years to complete. Comprehensive analysis of certain
pieces at UdeMs Ecomorphology and Paleoanthropology Laboratory
revealed undeniable traces of human activity in 15 bones. Around
20 other fragments also showed probable traces of the same type
Series of straight, V-shaped lines on the surface of the
bones were made by stone tools used to skin animals, said
Burke. These are indisputable cut-marks created by humans.
Bourgeon submitted the bones to further radiocarbon dating. The
oldest fragment, a horse mandible showing the marks of a stone tool
apparently used to remove the tongue, was radiocarbon-dated at 19,650
years, which is equivalent to between 23,000 and 24,000 cal BP (calibrated
years Before Present).
Our discovery confirms previous analyses and demonstrates
that this is the earliest known site of human settlement in Canada,
said Burke. It shows that Eastern Beringia was inhabited during
the last ice age.
Beringia is a vast region stretching from the Mackenzie River
in the Northwest Territories to the Lena River in Russia. According
to Burke, 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.
Our discovery confirms the Beringian standstill
[or genetic isolation] hypothesis,' she said, 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, colonized the entire
continent along the coast to South America.
The results of Lauriane Bourgeons doctoral research were
published in the January 6 edition of PLoS One under the title Earliest
Human Presence in North America Dated to the Last Glacial Maximum:
New Radiocarbon Dates from Bluefish Caves, Canada. The article
is co-authored by Professor Burke and by Dr. Thomas Higham of Oxford
Universitys Radiocarbon Accelerator Unit, in the U.K.