How did dogs get to America? An old bone fragment holds flashes

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

Credit: Credit: Douglas Levere / University in Buffalo

BUFFALO, NY – The history of dogs has been intertwined, from ancient times, with the history of the people who sent them home.

But how far back does that history go in America, and what route would dogs use to enter this part of the world?

A new study led by the University of Buffalo gives us an insight into these issues. The study reports that a bone fragment found in southeastern Alaska belongs to a dog that lived in the area about 10,150 years ago. Scientists say the remains – a piece of femur – represent the remains of a domestic dog in America.

DNA from the bone fragment holds evidence of early canine history in this part of the world.

Researchers analyzed the dog’s mitochondrial genome, and concluded that the animal belonged to a series of dogs that had an evolutionary history dating from the history of Siberian dogs as early as 16,700 years ago. That split comes at a time when people may have been migrating into North America on a coastal route that included the east coast. -south Alaska.

The research will be published on February 24 in the Proceedings of the Royal Society B.. Charlotte Lindqvist, an evolutionary biologist from UB, was the lead author of the study, which included scientists from UB and the University of South Dakota. The findings add to a growing knowledge of moving dogs into America.

“We now have genetic evidence from an ancient dog found on the Alaskan coast. Because dogs act as a surrogate for human habitation, our data helps not only time but also supports the introduction of dogs and humans to America, supporting the theory that this migration occurred just as coastal glaciers returned during the last Ice Age, “says Lindqvist, PhD, senior associate professor of biological sciences at UB College of Arts and Sciences. “Many waves of dogs have entered America, but one question has been, when did the first dogs arrive? And did they follow an ice – free passage inside the huge ice sheets that covered the continent of North America, or had their first migration on the coast? “

“The fossil record of ancient dogs in America is endless, so any new remains found provide important clues,” says Flavio Augusto da Silva Coelho, UB PhD student in biological sciences, and one of the first authors of the paper. “Prior to our study, the ancient bones of American dogs whose DNA was traced were found in the U.S. Midwest.”

Amazing result from a large collection of bones

Lindqvist’s team did not want to examine dogs. The scientists came across the femur fragment while tracing DNA from a collection of hundreds of bones excavated years earlier in Southeast Alaska by researchers including Timothy Heaton , PhD, professor of earth sciences at the University of South Dakota.

“It all started with our interest in how the Ice Age climate changes affected the survival and movements of animals in this region,” Lindqvist says. “Southeast Alaska may have been a place stop sort of, and now – with our dog – we think early human migration through the area could be much more important than some before. “

The bone fragment, which was thought to have originally come from a bear, was very small, but when the DNA was examined, the team realized that it was from a dog, Lindqvist says.

After this amazing discovery, the scientists compared the mitochondrial genome of the bone to those of other ancient and modern dogs. This analysis showed that a Southeast Alaskan dog shared a common ancestor about 16,000 years ago with American canines that lived before the arrival of European settlers, Lindqvist says. (Mitochondrial DNA, inherited from the mother, represents a small fraction of the total DNA of an organism, so a sequence of a complete nuclear genome could provide more detail if that material can be -mach.)

Interestingly, a carbon isotope study of the bone marrow reveals that the Southeastern Alaskan dog appeared to have a marine diet, which may have included foods such as fish and scraps. from seals and whales.

The research adds depth to the serial history of how dogs came to live in America. As Lindqvist points out, canines did not arrive immediately. For example, some Arctic dogs later arrived from East Asia with Thule culture, while Siberian huskies were introduced to Alaska during the Gold Rush. Other dogs were brought to America by European settlers.

The new study sharpens the debate over dogs and human migration into America.

“Our early dog ​​from southeastern Alaska supports the idea that the first dog and human migration occurred through the Northwest Pacific Coast Path instead of the central corridor of the continent, which it is thought to have become operational just about 13,000 years ago, “Coelho notes.

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

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