"Dog is man's best friend" may be an ancient cliché, but newly discovered evidence shows that humans in America have been forming deep bonds with dogs much earlier than previously thought.
In a study published in the journal Science Advances, researchers were able to demonstrate that people began forming close relationships with the ancestors of today's dogs as early as 12,000 years ago — about 2,000 years earlier than previously recorded in the Americas.
"People like me who are interested in the peopling of the Americas are very interested in knowing if those first Americans came with dogs," François Lanoë, lead author and University of Arizona researcher, said in statement. "Until you find those animals in archaeological sites, we can speculate about it, but it's hard to prove one way or another. So, this is a significant contribution."
Researchers unearthed a tibia, or lower-leg bone, of an adult canine in 2018 at a longstanding archaeological site called Swan Point, about 70 miles south east of Fairbanks. Radiocarbon dating showed that the canine was alive about 12,000 years ago, near the end of the Ice Age.
Another excavation by the researchers in June 2023 – of an 8,100-year-old canine jawbone at a nearby site called Hollembaek Hill, south of Delta Junction – also shows signs of possible domestication.
Chemical analyses of both bones found "substantial" contributions from salmon proteins, meaning the animal had regularly eaten fish. Researchers say this was not typical of canines in the area during that time, as they hunted land animals almost exclusively.
The study suggests the most likely explanation for salmon showing up in the animal's diet is from dependence on humans.
"This is the smoking gun because they're not really going after salmon in the wild," said study co-author Ben Potter, an archaeologist with the University of Alaska Fairbanks.
The researchers are confident that the Swan Point canine helps establish the earliest known close relationships between humans and canines in the Americas. But it's too early to say whether the discovery is the earliest domesticated dog in the Americas.
Lanoë noted that the Swan Point and Hollembaek Hill specimens may be too old to be genetically related to more recent dog populations; that they could have been tamed wolves rather than fully domesticated dogs.
"Behaviorally, they seem to be like dogs, as they ate salmon provided by people," he said, "but genetically, they're not related to anything we know."
Still, the study adds to evidence that forming relationships with dogs is a long-standing cultural tradition in America, stretching back thousands and thousands of years.