WASHINGTON, July 23 (Xinhua) -- Dogs can feel jealous if they think you pay more attention to other dogs, a U.S. study said Wednesday.
Scientists generally view jealousy as an emotion requiring complex cognition, but some research suggests there may be a more basic form of jealousy, which evolved to protect social bonds from interlopers.
Some researchers predict that jealousy might even exist in other social species, like the cognitively sophisticated dog.
Since there had been no prior experiments on dog jealousy, researchers from University of California San Diego modified a test used to assess jealousy in six-month-old human infants.
Thirty-six dogs were individually tested and videotaped while their owners ignored them in favor of a realistic looking stuffed dog, a jack-o-lantern pail or a book.
The three tests were set up to test whether dogs' behaviors were indicative of jealousy or a more general negative affect due to the loss of the owner's attention. The dogs' behavior was then analyzed for aggression, attention seeking, and/or interest in the owner or object.
The researchers found that dogs were about twice as likely to push or touch the owner when the owner was interacting with the faux dog (78 percent) as when the owner was attending to the pail (42 percent). Even fewer (22 percent) did this in the book condition.
About 30 percent of the dogs also tried to get between their owner and the stuffed animal. And while 25 percent snapped at the "other dog," only one did so at the pail and book.
"Our study suggests not only that dogs do engage in what appear to be jealous behaviors but also that they were seeking to break up the connection between the owner and a seeming rival," said lead author Christine Harris of the University of California San Diego.
"We can't really speak to the dogs' subjective experiences, of course, but it looks as though they were motivated to protect an important social relationship," Harris said.
These results, published in the U.S. journal PLOS ONE, supported the idea that jealousy may have some primordial form that exists in human infants and in at least one other social species: dogs.
The findings also supported the view that jealousy evolved to secure resources, not just in the context of sexual relationships, but also in any of a wide-range of valued relationships, such as competing for parental resources such as food, attention, care, and affection.
"Many people have assumed that jealousy is a social construction of human beings -- or that it's an emotion specifically tied to sexual and romantic relationships," Harris said. "Our results challenge these ideas, showing that animals besides ourselves display strong distress whenever a rival usurps a loved one's affection."