That man’s best friend gets jealous will come as no surprise to many owners who, when saying hello to another dog, have seen their own dogs get upset.
Scientists have been arguing for years, however, over whether jealousy requires complex thought and therefore something a dog’s brain can’t quite master.
And some researchers have said jealousy is entirely social, not seen in all human cultures and not fundamental or hard-wired in the same ways as other emotions such as fear and anger.
The current study, published in the journal PLOS ONE by University of California, San Diego, psychology professor Christine Harris and former honours student Caroline Prouvost, is the first experimental test of jealous behaviours in dogs.
The findings support the view there is a more basic form of jealousy, which evolved to protect social bonds from interlopers.
In the experiment, dogs showed jealous behaviours, such as snapping and pushing at their owner or a rival, when the owner showed affection to what appeared to be another dog (actually a stuffed dog which barked, whined and wagged its tail).
Dogs exhibited these behaviours more than if the same affection was showered on a novel object – and much more than when the owner’s attention was simply diverted by reading a book.
“Our study suggests not only that dogs do engage in what appear to be jealous behaviours but also that they were seeking to break up the connection between the owner and a seeming rival,” Harris said.
“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.”
The majority of research on the topic is on jealousy between human mates.
But a great deal of jealousy in humans concerns siblings, friends and even close co-workers.
Understanding jealousy is important, the researchers write, because it is an emotion with far-reaching psychological and social consequences.
For example, it often emerges as the third leading cause of murder.
“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.”
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