"Dog is man's best friend" may be an ancient cliché, but when that friendship began is a longstanding question among scientists.
A new study led by a University of Arizona researcher is one step closer to an answer on how Indigenous people in the Americas interacted with early dogs and wolves.
The study, published Wednesday in the journal Science Advances and based on archaeological remains in Alaska, shows that people and the ancestors of today's dogs began forming close relationships as early as 12,000 years ago – about 2,000 years earlier than previously recorded in the Americas.
"We now have evidence that canids and people had close relationships earlier than we knew they did in the Americas," said lead study author François Lanoë, an assistant research professor in the U of A School of Anthropology in the College of Social and Behavioral Sciences.
"People like me who are interested in the peopling of the Americas are very interested in knowing if those first Americans came with dogs," Lanoë added. "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."Lanoë and his colleagues unearthed a tibia, or lower-leg bone, of an adult canine in 2018 at a longstanding archeological site in Alaska called Swan Point, about 70 miles southeast 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.
The smoking gun? A belly of fish
Chemical analyses of both bones found substantial contributions from salmon proteins, meaning the canine had regularly eaten the fish. This was not typical of canines in the area during that time, as they hunted land animals almost exclusively. The most likely explanation for salmon showing up in the animal's diet? 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.