Hunter-gatherers sharing leftovers with wolves may have helped early dog domestication

Despite wolves being dangerous pack-hunting predators, these large animals were the first species domesticated by humans — but how and why we came to rear dogs remains unclear.

Paleolithic humans and wolves had the capacity to kill each other, but new research suggests some of the key early interactions which led to domestication could have been when people fed them leftover scraps of meat.

During harsh winters at the end of the last ice age, around 14,000 to 29,000 years ago, hunter-gatherer tribes may have fed some lean meat to wolf packs instead of competing with wolves for scarce resources, according to scientists from Finland.

Maria Lahtinen, from the University of Helsinki and the Finnish Food Authority, and her colleagues made the estimations, which could change existing understanding of likely domestication processes, by calculating how much energy would have been left over by humans from the meat of species they may have hunted at the time.

Typical species both wolves and humans would have hunted for meat included horses, moose and deer.

The authors hypothesised that if wolves and humans had always hunted the same animals during harsh winters, humans would have killed wolves to reduce competition rather than domesticate them.

However, the authors note that in winter months, the fat to lean meat ratio of prey mammals changes, as animals use up their fat reserves in cold weather. This crucial seasonal difference left large amounts of protein which would not have been desirable to hunter-gatherer populations who sought fattier cuts of meat.

So although humans may have relied on an animal-based diet during winters when plant-based foods were limited, they were probably not adapted to an entirely protein-based diet and may have favoured meat rich in fat and grease over lean, protein-rich meat.

The researchers said that with the exception of the mustelid group of mammals, which includes weasels, all prey species would have supplied more protein than humans could consume, resulting in an excess lean meat that could be fed to wolves, thus reducing the competition for prey.

As wolves can survive on a solely protein-based diet for months, humans may have fed this excess lean meat to early pets.

“Feeding excess meat to wolves may have facilitated co-living with captured wolves and the use of pet wolves as hunting aids and guards may have further facilitated the domestication process, eventually to full dog domestication,” the authors said.

“This ‘overproduction’ of protein in arctic and subarctic environments could easily have been fed to wolves/dogs when kept as a pet. Therefore, in the short term over the critical winter months, wolves and humans would not have been in competition over resources and may have mutually benefited from each other’s companionship.

“This would have been critical in keeping the first proto-dogs for years and generations. Hunter-gatherers are known to take pets, thus the idea that palaeolithic people captured wolf pups for pets is reasonable,” the study says.

Existing genetic studies indicate dogs descend from extinct wolf populations which split from the ancestors of living wolves between 27,000–40,000 years ago.

But it is believed that rather than being a single event, domestication was likely to be a complex process with dogs continuing to interbreed with wild wolves.

“There is little doubt that similarities between human and wolf societies facilitated in the process of wolf domestication,” the authors said.

“The excess protein not required by humans “could have been a significant impetus for wolves to become ‘our best friend’,” they conclude.

The research is published in Nature Scientific Reports.