Researchers have found that dogs and wolves have a sense of fair play that, in dogs at least, predates domestication. Thus, it's not a trait that dogs learned from humans.
Fair play, or a sensitivity or aversion to inequity, is an important human behavioral trait. Scientists say that this trait is what enabled cooperative behavior to evolve in humans. Fair play is what stops us from working with people who have treated us badly or unfairly. An earlier study found that dogs also exhibit this behavioral trait. Dogs don't like it when they that another dog is getting preferential treatment.
Scientists used to think that dogs may have learned fair play from humans. However, researchers have found that wolves exhibit this trait as well. This is evidence that dogs have had this trait before domestication. Thus, they didn't learn it from humans. Fair play is something that dogs and wolves may have inherited from a common ancestor.
In a newer study, researchers tested dogs and wolves that had grown in packs. The researchers trained the animals to press a button with their paw upon prompting from their trainer. When the animals press the button, they receive a treat. There are times, however, that the animal in testing does not receive a treat.
The researchers placed two dogs or two wolves in adjacent cages for the experiment. These cages had a button that emitted a buzzing sound. When one of the animals pressed the button, there were times when they both received a treat. There were also times that neither animal received anything. Other times, the animal that pressed the button got nothing while the other animal got a treat. There were also times that both animals got a treat, though the one that pressed the button got a clearly inferior treat.
For both dogs and wolves, unfair treatment—getting no treat or an inferior treat while doing all the work—made them stop cooperating. They eventually refused to keep pressing the button. What's interesting to note, however, is that the dogs and wolves continued cooperating when they didn't have a partner.
Thus, the researchers figured that seeing another animal get preferential treatment violates the animals' sense of fair play. The researchers also discovered that dogs and wolves with higher rankings in their packs began refusing to cooperate sooner than the other animals. This may be because they're less used to getting less than what they think they deserve.
What's even more interesting is how the animals interacted with their trainers and handlers after the experiments. The wolves that experienced unfair treatment became aloof toward their human handlers. The dogs, however, were not as aloof. This may be because domestication made them less sensitive to inequity.
This may have been an important development, since cooperation is vital in domestication. Dogs had to become more tolerant to inequities they experience with humans. Humans may not have developed a sense of fair play in dogs, but we have certainly impacted it.
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