What Wolf Pups That Play Fetch Reveal About Your Dog
Imagine a human sitting by the proverbial campfire about 15,000 years ago with a few young puppies. This would have been early in the dog domestication saga, so the human may have been considering what the pups were good for. Food? Fur? Noble companion?
So let’s suppose the human tossed a stick. Several puppies ignored it, but one waddled off at a puppy trot to chase it, and at the human’s urging, brought it right back. Hmm, the human thought, no stew pot for you.
This is a purely imaginary scene. Scientists have not discovered a new cave painting of the very first game of fetch. But Christina Hansen Wheat and Hans Temrin, biologists at Stockholm University, have found something almost as intriguing. They observed eight-week-old wolf puppies retrieve a thrown ball at the urging of a stranger, without any training.
Only three of 13 pups, over several years of testing, played fetch. And they were far from perfect. So it’s not as if this is a hidden talent of all wolves. But the researchers say that if the ability to engage with people this way is present in some wolves, it seems likely that it was present in the ancient wolves, now extinct, that were the ancestors of dogs, rather than evolving from new mutations during domestication.
This is the first evidence, reported Thursday in iScience, of this kind of responsiveness in untrained wolves, Dr. Hansen Wheat said. “To my knowledge, nobody has tested play behavior in wolves before,” she said. If she’s right, the ability to engage with humans in play is “a very old trait” that goes back to the very beginning of dog domestication, she added.
“I still get goose bumps when I tell you about this,” she said.
Elinor Karlsson at the Broad Institute in Cambridge, who studies the genetics of dogs, said the presence of the behavior in wolves was “completely consistent” with what we know about dog evolution.
The tests that led to the finding were important, she said, because “I think we too often assume that things we observe in dogs are special and unique, without really ever proving that.”
Elaine Ostrander, who runs the Dog Genome Project at the National Institutes of Health, was less positive. She pointed out that the authors had “a very small data set of just 13 wolves, of which only three were responsive and not fully responsive at that.”
And based on her personal experience as a dog owner, she said: “Many dogs will never return a ball.”
Dr. Hansen Wheat’s point is not that ball fetching itself is important, but that it shows a kind of social engagement that she didn’t expect to see in wolf puppies. Dr. Ostrander acknowledges that, but still wonders whether ball fetching is the best trait to study.
Dr. Hansen Wheat and Dr. Temrin tested three litters of hand-raised wolf pups, the first in 2014 and two others in 2015 and 2016. They used a test that is standard in Sweden to assess a range of behaviors in dog puppies, like sociability, curiosity and playfulness. The researchers had an experienced “puppy assessor,” a stranger to the puppies, administer the test, while they observed and recorded the behavior.
In one part of the test the assessor threw a ball, waited to see if the puppy played with it and then called to the puppy to bring it back. Each pup got three tries. Until the 2016 litter only one pup even paid the ball any attention. But in the 2016 litter, three of six wolves brought the ball back to the tester. Each pup had three tries. One did it all three times. The other two fetched the ball two out of three tries.
Dr. Hansen Wheat would very much like to get more data, on more wolves, but she said that the research with just a few pups was enough to show that the innate behavior was present in some wolves and was probably present in dog ancestors.
To understand what happened in domestication, researchers try to separate out traits that resulted from new mutations as humans created new kinds of dogs, and traits that were already present to some extent in ancient wolves.
The short legs of Corgis, bulldogs and dachshunds, or the flat faces of pugs, are the result of mutations that occurred while humans were developing new dog breeds. Another dog ability, to digest starch better than wolves, developed in a more complicated way. It resulted from an increase in the number of copies of a specific gene. Even among dog ancestors, the gene seems to have been present in different numbers of copies in different animals, implying that it was not related to domestication.
Dr. Karlsson said that the study of domestication needs “more research like this new paper.” And, she added, since it has been a very short evolutionary time since dogs and wolves split, “Our assumption should be that dogs and wolves won’t differ.”
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