How did dogs get to America? An ancient bone fragment contains traces

PICTURE: This bone fragment, found in southeastern Alaska, belongs to a dog that lived about 10,150 years ago, the study concludes. Scientists say the remains, a piece of femur, provide … a view more

Credits: Credits: Douglas Levere / University of Buffalo

BUFFALO, NY – The history of dogs has been intertwined since ancient times with the people who domesticated them.

But how far does that history go to America and which way did dogs enter this part of the world?

A new study led by the University of Buffalo provides insight into these issues. The research reports that a bone fragment found in southeastern Alaska belongs to a dog that lived in the region about 10,150 years ago. Scientists say the remains – a piece of femur – are the oldest confirmed remains of a domestic dog in America.

The DNA from the bone fragment contains traces of the early history of dogs in this part of the world.

The researchers analyzed the dog’s mitochondrial genome and concluded that the animal belongs to a lineage of dogs whose evolutionary history differed from the history of Siberian dogs as early as 16,700 years ago. The time of this separation coincides with the period when people may have migrated to North America along a coastal route that included southeastern Alaska.

The research will be published on February 24 in Proceedings of the Royal Society B. Charlotte Lindqvist, an evolutionary biologist from UB, was the senior author of a study that included scientists from UB and the University of South Dakota. The findings increase the amount of knowledge about the migration of dogs to America.

“We now have genetic evidence of an ancient dog found along the Alaskan coast. Since dogs are a substitute for human occupation, our data help determine not only the time but also the place of entry of dogs and humans into America. Our research supports the theory that this migration occurred just when coastal glaciers retreated during the last ice age, ”says Dr. Lindqvist, Associate Professor of Biological Sciences at UB College of Arts and Sciences. “There were several waves of dogs migrating to America, but one question arises, when did the first dogs arrive? And did they follow an ice-free inner corridor between the massive ice sheets that covered the North American continent, or was their first migration along the coast?” “

“Fossil data on ancient dogs in America are incomplete, so all the new remains found give important clues,” says Flavio Augusto da Silva Coelho, a doctoral student in biological sciences and one of the first authors. “Prior to our study, the oldest ancient American dog bones with DNA sequencing were found in the American Midwest.”

A surprising discovery from a large collection of bones

Lindqvist’s team did not embark on the study of dogs. Scientists found a fragment of the femur during DNA sequencing from a collection of hundreds of bones excavated years ago in southeastern Alaska by researchers, including Dr. Timothy Heaton, a professor of earth sciences at the University of South Dakota.

“It all started with our interest in how ice age climate change has affected the survival and movement of animals in this region,” Lindqvist says. “Southeast Alaska could have served as a kind of ice-free stop, and now – with our dog – we think early human migration through the region could be much more important than some previously suspected.”

The bone fragment, originally thought to come from a bear, was quite small, but when the DNA was studied, the team realized it was from a dog, Lindqvist says.

After this surprising discovery, scientists compared the mitochondrial genome of bone with that of other ancient and modern dogs. This analysis showed that a dog from southeastern Alaska shared a common ancestor about 16,000 years ago with American fangs that lived before the arrival of European colonizers, Lindqvist says. (Mitochondrial DNA, inherited from the mother, is a small part of the complete DNA of an organism, so sequencing the complete nuclear genome could provide additional details if that material can be extracted.)

Interesting is the carbon isotope analysis on a bone fragment that suggests that an ancient dog from southeastern Alaska probably had a seafood diet, which may have consisted of foods like fish and the remains of seals and whales.

The research adds depth to the layered history of how dogs inhabited America. As Lindqvist observes, the canines did not arrive at once. For example, some Arctic dogs arrived later from East Asia with Thule culture, while Siberian Huskies were imported to Alaska during the Gold Rush. Other dogs were brought to America by European colonizers.

A new study sharpens the debate on the migration of dogs and humans to America.

“Our early dog ​​from southeast Alaska supports the hypothesis that the first migrations of dogs and humans occurred along the coastal route of the Northwest Pacific instead of the central continental corridor, which is thought to have become sustainable only about 13,000 years ago,” notes Coelho.

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The research was funded by the National Science Foundation. In addition to Lindqvist, Coelho and Heaton, the authors of a new paper in Proceedings of the Royal Society B included Stephanie Gill and Crystal Tomlin.

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