A fragment of 10,000-year-old dog bones found along the Alaska coast may be the oldest evidence of domestic dogs in North America, and possible evidence of a coastal route that crossed the first humans from Eurasia to North America .
The evidence is growing for the Coastal Migration Theory, which suggests that instead of traveling through an entrance between two melting ice sheets, Eurasian migrants embrace the Siberian, Beringian, and Alaska coastlines. These settlers continued their journey along the Pacific coast and eventually reached the southernmost boundary of the massive Cordilleran ice sheet, according to this theory.
The Coastal Migration Theory, also known as the Kelp Highway hypothesis, is supported by geological and archaeological evidence, including 29 human footprints found off the coast of Calvert Island in British Columbia. We now have further evidence to support this theory, but it comes from an unexpected source: a tame dog.
This dog died about 10,150 years ago in what is now Alaska at the end of the last Ice Age. According to new research, led by evolutionary biologist Charlotte Lindqvist of the University of Buffalo, the lone fossil – a piece of a femur – is now the oldest remnant of a tame dog in America. The article describing this discovery was published on Tuesday in Proceedings of the Royal Society B.
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That Alaska offered dogs around this time is not a big surprise. Research presented from 2019 testimony of three prehistoric dogs buried in what is now Illinois, and dated between 9,630 and 10,190 years ago, the latter indicates a date slightly older than the date the femur presented in the new article. I asked Lindqvist about this apparent contradiction.
“If you compare the average radiocarbon dates of the Illinois dogs and our dog, the Alaska dog is a little older,” she said. ‘But it depends on what you’re comparing, and with the error bars and uncertainty – and radiocarbon dating done by different labs – you can argue that it’s at least the same age, possibly with the Alaska dog a few hundred. years older. ”
The Illinois dogs are important because they suggest that the first settlers from North America brought their dogs from Eurasia. Previous genetic research what was done in this area came to a similar conclusion and showed that dogs arrived in America about 10,000 years ago.
Lindqvist and her colleagues accidentally came across the femur while searching for DNA sequences from a tangle of animal bones excavated from caves in southeast Alaska. This research is being done to determine how climate change during the last Ice Adifferent types affected, including their motility.
“One of the projects I’m working on involves black and brown bears, and we initially thought the bone came from a bear, but we later discovered it was a dog, and we had to follow up on this finding,” he said. Lindqvist explained in an email.
The dog’s femur fragment, named PP-00128, was found on the southeastern Alaska mainland just east of Wrangell Island at a location known as Attorney Cave. Lindqvist, along with her co-author Timothy Heaton, a professor of Earth Sciences at the University of South Dakota, conducted a number of excavations in the late 1990s and early 2000s., which led to the discovery of this bone and many others from the same cave.
The team was able to obtain a complete mitochondrial genome from the fragment, which they compared with modern dog breeds, historic Arctic dogs and American pre-contact dogs (ie dogs that lived in the Americas before the arrival of the Europeans). Mitochondrial DNA comes exclusively from maternal side, so it is incomplete (compared to nuclear DNA), but scientists were able to trace the genome back to a genus that deviated from Siberian dogs about 16,700 years ago.
This is important as this timing roughly coincides with the minimum proposed date for the opening of the North Pacific coast along the Cordilleran ice and genetic evidence for the initial population of the Americas, ‘as the authors wrote in the study.
Indeed, the PP-00128 fragment provides another clue in favor of the coastal migration hypothesis. The coastal edge of the ice sheet started melting about 17,000 years ago, while the inland corridor first opened about 13,000 years ago.
‘Previous genetic estimates of the distribution between pre-European American dogs and their Siberian ancestors were younger than the estimates when the ancestral Native American human population deviated from their Siberian ancestors, suggesting that dogs arrived in later migrations of humans to the Americas , maybe even next to the entrance, ”Lindqvist explained.
Prior to the new study, “the oldest U.S. dog remains from mid-continental areas were found, which does not suggest how they got there,” she said, but this latest discovery “supports that our coastal dog is a descendant of dogs that participate in this initial participation.Migration along the Northwest Pacific Coast.”
Of course, there is a possibility that it was a rogue dog that somehow came to North America without people. It is not as strange as it may seem; dogs were domesticated from wolves between 14,000 and 29,000 years ago, in a complex process involving multiple cross-breeding episodes between dogs and wild wolves. That said, Lindqvist believes her Alaska dog probably lived with humans.
‘Other remains excavated from the same cave include human bones and works of artfacts, but it’s all younger, ”she said. “They suggest that the cave is used by humans. And we know from human remains found in another cave in southeast Alaska that people were in the area at the time this old dog lived. But no, we do not have direct evidence that this dog lived with humans. We do know that this dog was a tame and not a wolf, and if I were a dog, I would probably stay with people to eat. ‘
Indeed, a carbon isotope analysis of the femur fragment indicates that this dog was fed by humans because he ate fish (possibly salmon), and meat of whales and seals. This is in stark contrast to other old dogs living in the middle continent who had a “much more earthy diet”, Lindqvist said.
That people traveled along the Pacific coast from Eurasia to North America seems highly probable, and the new research fits in well with this increasingly popular story. But that does not mean that alternative roads to the mainland have been neglected. As previous research shows, there were probably more than one route North America in, since an entrance probably opened about 12,600 to 13,100 years ago.