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.