Dogs passed near Wrangell on their way south 10,000 years ago

It was an international effort that started on a long journey about 10,000 years ago through what is now a cave on the mainland, across Blake Channel from Wrangell Island.

A bone chip smaller than a dime, found almost 25 years ago by a University of South Dakota researcher, was being held at the University of Alaska Fairbanks Museum of the North. It was examined again by scientists with the University at Buffalo, State University of New York, who published their study last month in the London-based Royal Society's flagship biological research journal.

The chip is a small piece of a leg bone from a dog that lived an estimated 10,150 years ago.

The piece of a femur is the oldest confirmed remains of a domestic dog in the Americas, according to the researchers.

The bone fragment was originally thought to come from a bear, but when the DNA was studied, the team realized it was from a dog, said University at Buffalo evolutionary biologist Charlotte Lindqvist, who was senior author of the study that also included scientists from the University of South Dakota.

"Because dogs are a proxy for human occupation, our data help provide not only a timing but also a location for the entry of dogs and people into the Americas. Our study supports the theory that this migration occurred just as coastal glaciers retreated during the last Ice Age," Lindqvist told the university's online newspaper, UBNow.

It was a long journey for dogs and their companions from what is now Alaska to the Pacific Northwest.

"There have been multiple waves of dogs migrating into the Americas, but one question has been, when did the first dogs arrive?" Lindqvist asked. "And did they follow an interior ice-free corridor between the massive ice sheets that covered the North American continent, or was their first migration along the coast?"

The research indicates that dogs, and humans, migrated south along the coast as the retreating glaciers opened the way.

"Our early dog from Southeast Alaska supports the hypothesis that the first dog and human migration occurred through the Northwest Pacific coastal route instead of the central continental corridor," said Flavio Augusto da Silva Coelho, a University at Buffalo Ph.D. student in biological sciences and one of the paper's first authors.

"Before our study, the earliest ancient American dog bones that had their DNA sequenced were found in the U.S. Midwest," Coelho told UBNow.

It was no Midwest diet for the Wrangell dog. Carbon isotope analysis on the bone fragment indicates that the ancient Southeast Alaska dog likely had a marine diet, which may have consisted of foods such as fish and scraps from seals and whales, researchers determined.

"The bone chip was discovered in Lawyer's Cave, also called Phalanges Phreatic Tube by cavers, referring to the cave's shape and the toe bones (phalanges) of a bear found inside," according to the research paper published in the Royal Society journal.

The cave has two entrances and is about 65-feet of "non-branching crawlway from end to end," the paper said. "Lawyer's Cave is rich in other postglacial remains beyond the specimen, including bones of various mammals, birds and fish, as well as human remains and artifacts that were discovered during two excavations in 1998 and 2003."

Lindqvist's team did not plan on going to the dogs. They were sequencing DNA from a collection of hundreds of bones excavated in the late 1990s from the cave by University of South Dakota researchers. "This all started out with our interest in how Ice Age climatic changes impacted animals' survival and movements in this region," Lindqvist told UBNow.

"Southeast Alaska might have served as an ice-free stopping point of sorts, and now - with our dog - we think that early human migration through the region might be much more important than some previously suspected," she said.

"The research adds depth to the layered history of how dogs came to populate the Americas," UBNow reported.