A dime-sized fragment of dog bone — more than 10,000 years old — has given researchers new clues about how domesticated dogs first made their way to the Americas.
Examining a pinto bean-sized bone fragment, the scientist thought she was analyzing an ancient bear bone.
“We have sort of a long standing project working on bear bones from these caves,” explained Charlotte Lindqvist. She’s an associate professor of biology at the State University of New York at Buffalo.
Caves are dotted across Southeast Alaska’s Alexander Archipelago. The fragment of leg bone Lindqvist examined came from a cave on the mainland just east of Wrangell Island. The cave is a marble tube, about the length of a standard swimming pool.
“This DNA, when we were looking at it and analyzing it, we realized: ‘This is not bear DNA,’” Lindqvist continued.
She and her colleagues realized the bone was from a dog, and published their findings in a scientific journal in late February.
Turns out, the dog lived around 10,000 years ago.
“That is among the oldest dog remains that we have from North America,” Lindqvist said. Ancient dog remains are a rare discovery on their own, but Lindqvist explains the location is also part of what makes this identification so exciting.
To understand why, it helps to look back to the Ice Age — which ended about 10,000 years ago.
“During the Ice Age most of North America was completely covered in these two big ice sheets. So there was no contact north and south of the ice sheet,” Lindqvist said.
A band of ice across Canada and the northern U.S. prevented the people living in northern Beringia — including what is now Alaska — from moving south into what’s now the Lower 48.
“There has been this long-standing hypothesis that as soon as these two ice sheets started melting, it opened up a sort of continental or inland corridor,” Lindqvist said. “If you have seen the Disney movie ‘Ice Age,’ that’s sort of what is displayed in that movie. But more and more, we’ve started to believe that the coast probably started melting earlier and became viable earlier than this inland corridor.”
And where you find a dog bone, man might not be far behind.
“Finding a dog on the coast can tell us a lot. Not just about dog migration and where dogs have been — but also humans, because dogs follow alongside humans.”
Human remains and tools from various points in ancient history have been found in the same cave off Wrangell Island.
The dog bone Lindqvist and her colleagues Flavio Augusto da Silva Coelho, Stephanie Gill and Crystal Tomlin analyzed was collected in the late 1990s by a now-retired earth science professor at the University of South Dakota named Timothy Heaton.
“Back in the late 90s, and early 2000s, he did multiple trips, and excavated bones from a number of caves in Southeast Alaska,” said Lindqvist.
The 50,000-odd bones now reside in the collections of the Museum of the North in Fairbanks.
The piece of dog femur may be tiny, but Lindqvist said it could still yield a lot of information.
“For now, we have just isolated the DNA from the mitochondria in this bone, and that is inherited from the mother. So it only tells us the maternal history of this dog. If we can, from this tiny little bone that we have left, get some nuclear DNA — DNA from the genome — we might be able to get deeper insights into the history of this particular dog and the history of New World dogs.”
Lindqvist said she hopes for other discoveries in the thousands of bones from Southeast caves that are left to analyze.
“I’m sure it’s not the last, and it will be exciting as we hopefully will find older remains as well.”
The cave off Wrangell Island has only been partially excavated: It is a heritage site, protected by federal law. Human remains from the site have been repatriated to Wrangell’s Tlingit tribe, the Wrangell Cooperative Association, under the Native American Graves Protection and Repatriation Act.
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