06 August 2008

Catching His Master’s Yawn

It’s not just Frisbees and sticks. Dogs catch yawns from people, too. Dogs watching a person yawn repeatedly will yawn themselves, says Atsushi Senju of Birkbeck, University of London. Just as that big jaw-stretch spreads contagiously from person to person, it spreads from person to dog, he and his colleagues report in an upcoming Biology Letters.

“It is contrary to what I've heard informally from a lot of dog owners who say they catch their dogs’ yawns, but their dogs never yawn when they do,” says psychologist Gordon Gallup Jr. of the State University of New York at Albany. The data are “pretty compelling” though, Gallup says of the new study. “If it can be replicated it strongly suggests dogs may have a primitive empathic capacity.”

Empathy, or the capacity to grasp what someone else feels, knows or intends, may depend on some of the same neural circuitry triggered by contagious yawning, Gallup says. Research from Gallup’s lab has suggested that people more susceptible to contagious yawning tend to show more capacity for empathy. Also, yawning doesn’t sweep contagiously among people with autism spectrum disorder, which is marked by difficulty with empathy, Senju’s lab reported last year.

One of Senju’s students, Ramiro Joly-Mascheroni, reported that he and his dog shared many a yawn, but no one had rigorously tested contagious yawning between species. So the lab invited dogs to try a possible yawner of a test. Subjects ranged from dachshunds to Dobermans, and all were unknown to Joly-Mascheroni. The dog’s owner sat quietly behind the dog while Joly-Mascheroni spent five minutes repeatedly catching the eye of the animal and giving a wide, sighing yawn. The test usually allowed time for about 10 yawns. For a control, Joly-Mascheroni followed the same procedure but just opened his mouth quietly and less dramatically.

Of the 29 dogs, 21 yawned at least once, usually after Joly-Mascheroni had reached number four in his series. When he just made the control mouth movements, though, none of the dogs yawned.

Senju says that it isn't clear from this experiment just why the yawns spread. The dogs’ yawning could reflect canine empathy with a human condition. Or the dogs may have learned to yawn along with people based on positive feedback during previous experiences. Or a human yawn might trigger a dog yawn because the gesture comes across as somewhat aggressive to a dog; macaques, for example, yawn in tense situations.

“It would be very interesting to see if contagious yawning occurs between dogs,” Gallup says. And there’s another possible direction for the contagion. “Although there are no studies about it, I think it’s quite likely that dogs’ yawns induce yawning in humans,” Senju says.

The news itself may bring on a yawn since, Senju says, even reading about the gesture, hearing the sound or imagining a yawn can create an irresistible urge.

[Source: Science News]