Do dogs feel envy? A provocative new study indicates that they do, making man's best friend the first species after humans and primates to appear to chafe at being treated unfairly.
Aside from offering the first scientific evidence supporting what many dog lovers take for granted, the finding adds to the growing body of literature suggesting that animals, including dogs, have much richer emotional lives and more sophisticated behavior than humans have traditionally believed.
"The more we study animals and the more we learn about them, the more we are realizing that maybe humans are somewhat different but not really all that different," said Friederike Range of the University of Vienna in Austria, who led the team that published the findings last week in the Proceedings of the National Academy of Sciences. "They have these kinds of feelings, or at least the precursors of these feelings, that we thought were uniquely human."
Before the new study, the only creatures other than humans for which there was evidence of anything similar to envy were monkeys and chimpanzees. When asked to return rocks to their keepers in exchange for a treat, for example, monkeys that got cucumbers essentially went on strike and started throwing the rocks and cucumbers at researchers if they saw other animals getting grapes instead.
To see whether dogs would respond with similar indignation, Range and her colleagues conducted a series of experiments involving 43 border collies, shepherds, retrievers, mutts, Rottweilers, terriers and other breeds. The researchers sat pairs of dogs next to each other with their owners standing behind them. The researchers then:
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Asked each dog repeatedly to give them a paw.
Rewarded each dog with either a piece of bread or sausage.
Showed that the pooches would eventually get upset if their partner was getting rewarded while they got nothing.
"The dogs that were not getting the reward started to hesitate. You had to prompt them more often to give the paw," said Range, noting that some of the deprived dogs would start acting frustrated, scratching themselves, licking their mouths and yawning. "They would refuse to look at you, start looking at their owners or at the other dog chewing, and eventually refuse to cooperate. They would look away or lay down and not give the paw anymore if they were not getting rewarded."
To rule out alternative explanations, the researchers conducted several variations of the test. For example, to see if the dogs were refusing to give their paw more out of frustration than from a sense of inequity, they repeated the experiment with dogs by themselves sometimes rewarding them and sometimes not. In that situation, the dogs continued to cooperate for much longer even when they were not getting a treat. The same thing happened when neither dog in a pair got rewarded.
"It's not just 'Oh, shoot. I'm not getting rewarded, so I stop working,' " Range said. "If both are not rewarded, that is not a big problem. But if you rewarded one and not the other, that's where you saw a problem."
Range hesitated to conclude with certainty that dogs feel what humans call envy. Instead, she used a more technical term: inequity aversion.
"It looks like there's something going on there. They are reacting to the inequity. They stop cooperating," Range said. "But what kind of feeling it is difficult to say."
Range argued the behavior was not motivated by a sense of "fairness" as humans typically define it. The dogs reacted only when they themselves were not rewarded -- not when another dog was denied a reward it deserved.
"If you think about a human situation, a human could say it's unfair that we both do the same task and you don't get the same reward and I get a reward. That's not the case for the dog. It's really self-centered," she said.
The dogs' sense of inequity aversion was also more primitive than that of the primates. They were satisfied whether they got a piece of bread or sausage for their performance, Range noted.
Range said she was not surprised by her findings. Many dog owners would probably argue that their dogs have expressed that behavior.
"Every dog owner will tell you, 'Yes, of course my dog has this.' You see it a lot if you have two dogs. If you treat one differently, then the other one would get angry," she said. But demonstrating it in a careful study helps dispel lingering notions that dogs and other animals are capable of only the most basic emotions, she said.
"It's definitely very interesting, because it shows that dogs don't just have primitive feelings like 'I'm afraid' or 'I'm happy.' This is a more higher level, deeper and profound," she said.
Other experts, while stressing that the study needs to be confirmed by additional research, praised the work as providing new evidence of the social acuity of animals.
"As time goes on, we're collecting an astounding amount of information about the social skills that animals have for negotiating their social world," said Marc Bekoff of the University of Colorado, author of the forthcoming book "Wild Justice," about animal morality. Bekoff noted, for example, that mice have shown signs of empathy for other mice in danger, that elephants will go out of their way to care for other injured elephants, and that coyotes will ostracize other coyotes who play unfairly.
"From an evolutionary point of view, there's very little that we have that other animals don't have. Do I think that dogs can be envious and show resentment and jealousy? Of course I think they can," Bekoff said.
The sense of envy probably evolved to help the animals cooperate and probably exists in other animals for which cooperation is important, such as wolves and perhaps dolphins, Range said. Understanding how animals cooperate provides insights into how cooperation evolved, she and others said.
"We're trying to understand how our ability to cooperate evolved, and one thing that is crucial is our ability to detect cheaters," said Brian Hare, an assistant professor of evolutionary anthropology at Duke University. "One of the things about humans is we can feel cheated, and because we can make those types of discriminations, more complex forms of cooperation can evolve."
The findings are especially intriguing given the current economic crisis, said Frans B.M. de Waal of Emory University, who did the initial experiments showing inequity aversion in monkeys and chimps.
"If you look at the crisis in the U.S. and the automobile industry, people are upset because the executives are driving private jets and we are driving lousy cars," deWaal said. "There are many studies of inequity aversion in humans. Economists have studied this and said only humans have this. This shows it's not limited to our species. Some of these elements are also evolved in other animals."
Dogs Feel Envy -- or at Least Grasp Inequity When It Comes to Treats - washingtonpost.com