Dogs exhibit more jealous behaviors, like snapping or pushing their owner, when their owners displayed affectionate behaviors towards what appeared to be another dog compared to random objects, according to a study published in the open-access journal PLOS ONE by Christine Harris and Caroline Prouvost from UC San Diego.
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. Scientists predict that jealousy, at its most basic level, might even exist in other social species, like the cognitively sophisticated dog. To evaluate dogs' jealous behaviors, scientists modified a test used to assess jealousy in 6-month old infants. Thirty-six dogs were individually tested and videotaped while their owners ignored them and interacted with a series of three different objects: a realistic looking stuffed dog, a jack-o-lantern, and 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 authors found that dogs exhibited significantly more jealous behaviors, such as snapping, getting between the owner and object, and pushing or touching the object or owner, when their owners displayed affectionate behaviors towards what appeared to be another dog as compared to the two nonsocial objects. These results support the idea that jealousy may have some primordial form that exists in human infants and in at least one other social species: dogs. The author's findings support 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.
Christine Harris added, "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. Our results challenge these ideas, showing that animals besides ourselves display strong distress whenever a rival usurps a loved one's affection."