It was thought that dogs only played fetch due to 15,000 years of domestication but scientists have now discovered that wolf cubs also play the game.
The finding suggests that this behaviour of fetching a ball may actually be somewhat innate to all canine species.
Researchers once believed that fetching games only arose when dogs were domesticated at a time when the human race still lived in caves.
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Animal experts were shocked to discover this when 13 wolf puppies from three different litters were tested in a behavioural test designed to compare them to young dog puppies.
In one test, three eight-week-old wolf puppies spontaneously showed interest in a ball and returned it to a perfect stranger upon encouragement.
Behavioural ecologist Dr Christina Hansen Wheat, of Stockholm University, said: “When I saw the first wolf puppy retrieving the ball I literally got goosebumps.
“It was so unexpected, and I immediately knew that this meant that if variation in human-directed play behaviour exists in wolves, this behaviour could have been a potential target for early selective pressures exerted during dog domestication.”
Dr Hansen Wheat and her team decided to examine both wolf and dog pups in the same way across 10 days, putting them through various behavioural tests.
In one test, a stranger threw a tennis ball across the room, and without the benefit of any previous training, encouraged the puppy to get it and bring it back.
The researchers said they did not expect wolf pups to catch on, and many of them chose to ignore the ball.
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But then some wolves decided to play fetch.
Dr Hansen Wheat said: “It was very surprising that we had wolves actually retrieving the ball.
“I did not expect that. I do not think any of us did. It was especially surprising that the wolves retrieved the ball for a person they had never met before.”
The wolf expert said the similarities between the two canine species can tell us about where the behaviour we see in dogs comes from.
She said the results, although probably rare, show our ancestors may have attempted to domesticate wolves as well as dogs.
She added: “Wolf puppies showing human-directed behaviour could have had a selective advantage in early stages of dog domestication.”
Her team will now continue to work with the data they have collected over the course of three years hand-raising wolves and dogs under identical conditions to learn even more about their behavioural differences and similarities.
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