Humans domesticated wild wolves at some point between 14,000 and 29,000 years ago, ultimately turning ferocious wolves into people's best friends over the course of many generations. But exactly how this relationship originated has been a hot topic among archaeologists.
Now, a new theory suggests that the relationship between humans and wolves started when hunter-gatherers in northern Eurasia tossed leftover meat from their hunts to wolf pups being raised as pets, setting off a mutually beneficial relationship and throwing a wrench—or in this case, a bone—into existing hypotheses about canine domestication, reports Bruce Bower for Science News. The researchers published their findings on January 7 in Scientific Reports.
Two main theories attempt to explain the origins of humans' relationship with dogs. One says that people recruited wolves to help them hunt, and the other suggests that humans left garbage piles when they moved around, attracting the wolves, George Dvorsky for Gizmodo. But lead author Maria Lahtinen, an archaeologist at the Finnish Food Authority, says there are flaws in both arguments, and the more likely answer is explained by the two species' differing diets.
"In our opinion, the self-domestication in this way is not fully explained," Lahtinen tells Gizmodo in an email. "Hunter-gatherers do not necessarily leave waste in the same place over and over again. And why would they tolerate a dangerous carnivore group in their close surroundings? Humans tend to kill their competitors and other carnivores."
To propose an alternative explanation, a team of scientists led by Lahtinen analyzed what ice age humans would've eaten throughout the year and how much protein, carbohydrates and fat their bodies would have needed, reports Tara Yarlagadda for Inverse. They found that animal protein could only provide up to 45 percent of the ice age humans' energy needs during the winter, reports James Gorman for the New York Times.
When plants became scarce in the winter, hunter-gatherers tweaked their diets to consume more fats and oils, such as from an animal's lower limbs, brain and organs, leaving plenty of lean meat. And since wolves are carnivores that are designed to have protein-rich diets, they were likely tossed the leftovers, reports Gizmodo.
"Therefore, the early domesticated wolves could have survived living alongside human populations by consuming the excess protein from hunting that humans could not," James Cole, an archaeologist at the University of Brighton in England who was not involved with the study, tells Gizmodo. "By having enough food for both populations, the competitive niche between the species is eliminated."
Since humans and wolves competed for the same prey items, they could share their kills and ease the competition. Wolves got easy access to meat, and in exchange, humans could have received help hunting prey or extra protection from other predators, reports Inverse.
With the pressures of competition eliminated, the two species could have sparked a mutually beneficial relationship that ultimately gave way to humans using wolves to hunt, pull sleds and act as guards, reports Inverse.
With selective breeding over the course of thousands of years, dogs ended up as beloved pets in our homes.