Dog Domestication Was a Messy Process, Claims Study of 76 Prehistoric Canines

Who let the dogs out? It remains unclear, but researchers are now one step closer to knowing how humankind’s canine companions got their start.

The domestication of dogs has a murky past. Humans have had furry friends for thousands of years, but the precise timeline of the domestication of canids into modern dogs is hard to pin down. The research, published today in Science Advances, offers specific timestamps for domestication—or something resembling it—from 76 ancient canid fossils found across Beringia.

“The general assumption has been that domestication happened once and clearly separated canids that interact with people (dogs) from those who don’t (wolves),” said François Lanoë, an archaeologist at the University of Arizona and lead author of the research, in an email to Gizmodo. “Our study instead show that canid-people relationships were complex, continue to be today, and involve more than domestication, but also things like taming of wild wolves and commensality (wolves hanging around human settlements).”

In other words, domestication happened to varying degrees, in different places, and at different points in the prehistoric past. That ambiguity is endorsed by some previous research, which suggested that prehistoric humans used early dogs as hunting partners, but some of the other canids were drawn to humankind by our rubbish piles and food.

For the new study, the team investigated 76 canid specimens—dogs and hybrid wolfdogs, but also wolves and coyotes—from late Pleistocene and Holocene sites in interior Alaska. The team also included modern wolf remains from Alaska in their morphological and genomic analyses, which indicated that some of the ancient canids on certain river sites had more salmon in their diet than other specimens in the dataset. Other canids in the data set had diets that included fish and game.

“This is the smoking gun because they’re not really going after salmon in the wild,” said Ben Potter, an archaeologist at the University of Alaska Fairbanks, in a University of Arizona release. “It asks the existential question, what is a dog?”

Though domestication has yielded breeds as disparate as the chihuahua and the great dane, some modern dogs still have a strong resemblance to their ancient forbears; in 2020, a different research team found that sled dogs have an unbroken genetic ancestry dating back to the end of the last ice age. Since ancient wild canids would not regularly hunt for salmon, the fishy finds are a useful barometer for when some of the animals began to warm up to humankind.

The Hollembaek Hill site, where a canine jawbone was found. Photo: Joshua Reuther

“I really like the idea that, in the record, however long ago, it is a repeatable cultural experience that I have this relationship and this level of love with my dog,” said Evelyn Combs, a Healy Lake member and an archaeologist for the tribe’s cultural preservation office, in the Arizona release. “I know that throughout history, these relationships have always been present. I really love that we can look at the record and see that thousands of years ago, we still had our companions.”

Other research into the history of dogs and their domestication has revealed everything from the origins of dog coats to how the creatures relate to wild dogs today. Work published in 2021 found that yellow dog coats, seen in breeds like the shiba inu, is inherited from an ancient canid that split from Pleistocene wolves a staggering two million years ago. While some ancient bonds remain unbroken, more recent relations between dogs and their close relatives today—namely the Australian dingo—aren’t that strong.

Lessons from the recent paper could also be applied to the interactions prior human groups had with other animals, including foxes—which are not not canids, despite their uncanny resemblance—and chickens, which evolved from junglefowl in southeast Asia. Fossil evidence provides some details of domestication, but so too do genetic analyses—as evidenced by a 2022 paper in which researchers studied 238 donkey genomes to home in on the domestication of the wild ass. The recent work’s leveraging of dietary analysis is a smart approach to the domestication question—we are human, after all, and remain fallible to the mournful gaze of puppy dog eyes begging for a bit of lox.

The jury remains out on who let the dogs, uh, out, but the latest research offers new hints at how the human-canine partnership began—even if those beginnings don’t have a clear-cut answer.