A 10,000-year-old dog bone fragment found along the Alaskan coast could be the oldest evidence of domesticated dogs in North America, and the potential evidence of a coastal route taken by the first people to cross into North America from Eurasia.
Evidence continues to rise for the theory of coastal migration, which proposes that Eurasian migrants, instead of traveling through an inner corridor between two melting ice sheets, embrace the Siberian, Beringian, and Alaska coasts. . These settlers continued their way along the Pacific coast, finally reaching the southernmost limit of the massive Cordilleran ice sheet, according to this theory.
The theory of coastal migration, also known as the Kelp road hypothesis, is supported by geological i archaeological tests, included 29 human footprints found off the coast of Calvert Island in British Columbia. We now have more evidence to support this theory, but it comes from an unexpected source: a domesticated dog.
This dog died about 10,150 years ago in present-day Alaska during the end of the last ice age. The lone fossil — a piece of femur — is now the oldest confirmed remnant of a dog domesticated in the Americas, according to new research, led by evolutionary biologist Charlotte Lindqvist of the University of Buffalo. The paper describing this discovery was published Tuesday in Proceedings of the Royal Society B.
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That Alaska was home to dogs at this time is no huge surprise. 2019 research is presented tests of three prehistoric dogs found buried in present-day Illinois, which were dated between 9,630 and 10,190 years ago, the latest figure suggests a date slightly older than the date presented for the femur in the new paper. I asked Lindqvist about this apparent discrepancy.
“When you compare the average radiocarbon dates of Illinois dogs and our dog, the Alaskan dog is a little bigger,” he said. “But it depends on what you’re comparing, and with the error bars and uncertainty — and the radiocarbon dating done by different labs — you can argue that they’re at least close to the same age, possibly with the Alaska dog at a couple of hundred years older ”.
Illinois dogs are significant, as they suggest that the first settlers in North America brought their dogs with them from Eurasia. Previous genetics research fact in this area came to a similar conclusion, which showed that dogs came to the Americas about 10,000 years ago.
Lindqvist and colleagues inadvertently stumbled upon the femur as they sequenced DNA from a tangle of animal bones dug in caves in southeast Alaska. This research is being done to determine how climate change during the last ice age affected several species, including their mobility.
“One of the projects I’m working on is black and brown bones and we initially thought the bone came from a bear, but later we found out it was a dog and we had to keep track of that finding,” he explained. Lindqvist in an email.
The canine femur fragment, named PP-00128, was found in southeastern Alaska Peninsula, east of Wrangell Island, at a site known as Lawyer’s Cave. Lindqvist, co-authored Timothy Heaton, a professor of Earth sciences at the University of South Dakota, conducted several excavations in the late 1990s and early 2000s, which resulted in the discovery of this bone and many others from this same cave.
The team was able to obtain a complete mitochondrial genome from the fragment, which it compared to modern breeds of dogs, historic Arctic dogs, and contactless American dogs (i.e., dogs that lived in the Americas before the arrival of the Europeans). Mitochondrial DNA comes exclusively from the maternal side, so it is incomplete (compared to nuclear DNA), but scientists were able to trace the genome back to a lineage that diverged from Siberian dogs about 16,700 years ago.
This is significant, as this “time roughly coincides with the suggested minimum date for the opening of the North Pacific coastal route along the Cordilleran ice sheet and the genetic evidence of the initial settlement of the Americas.” as the authors wrote in the study.
In fact, fragment PP-00128 presents another clue in favor of the coastal migration hypothesis. The shoreline of the ice sheet it began to melt about 17,000 years ago, while the inner corridor it did not open until about 13,000 years ago.
“Previous genetic estimates of the division between pre-European American dogs and their Siberian ancestors were younger than estimates of when the Native American ancestral human population became detached from their Siberian ancestors, suggesting that the dogs reached human migrations. later to the Americas along the inner corridor, ”Lindqvist explained.
Prior to the new study, “the remains of older American dogs were found in places on the Middle Continent, without suggesting how they got there,” he said, but this latest discovery “supports the fact that our coastal dog is a descendant of dogs that participated in this initial migration along the Pacific Northwest coast. “
Of course, there is a possibility that it was a rogue dog that somehow headed to North America without humans. This is not as extravagant as it might seem; dogs were domesticated by wolves between 14,000 and 29,000 years ago, in a complex process that involved multiple episodes of crossbreeding between dogs and wild wolves. That said, Lindqvist believes his Alaskan dog probably lived with humans.
“Other remains excavated in this same cave include human bones and artifacts, but they are all younger,” he said. “But they suggest the cave was used by humans. And we know from human remains found in another cave in southeast Alaska that humans were in the region at the time this ancient dog lived. But no, no we have direct evidence that this dog lived with humans. We know, however, that this dog was a domesticated and not a wolf, and that if it were a dog, I would probably stay around humans to eat. “
In fact, a carbon isotope analysis of the femur fragment suggests that this dog was fed by humans, as it ate fish (possibly salmon) and whale and seal meat. This contrasts with other ancient dogs living on the middle continent, which featured a “much more terrestrial diet,” Lindqvist said.
Ben Potter, an archaeologist at the Arctic Studies Center at Liaocheng University in China, had some concerns about this. new study.
“It simply came to our notice thenheast Alaska was occupied 12,600 years ago, which is 2,400 years before the dog, ”he explained by email. “So it’s not entirely informative about the routes of the first Native Americans about 4,000 to 5,000 years ago.”
This huge time gap, he said, is “equivalent to the emergence of the first states in the Middle East (ancient Egypt and Mesopotamia) and today.”
To which Potter added, “Our review of the data indicates that the inner route of the ice-free corridor was available at least 14,900 years ago.”
That humans travel the Pacific coast from Eurasia to North America seems highly likely and new research fits very well with this increasingly popular narrative. But this does not mean that alternative routes to the continent were neglected. As Potter points out, there probably were more than one route in North America, as an inland corridor probably opened about 12,600 to 14,900 years ago.
This post was updated to include comments received by Ben Potter.