September 17, 2008
Dogs Catch Human Yawns
Spying someone yawning often makes us yawn. Now, a new study shows your canine buddy can catch yawns from you, too.
The results suggest domestic dogs have the capacity for a fundamental form of empathy, the researchers say.
The phenomenon, called contagious yawning, has been found only in humans and other primates such as chimpanzees and is thought to relate to our ability to empathize with others. Past studies, however, involved yawning within one species at a time, so for instance chimps that triggered other chimps to yawn and humans prompting yawns in other humans.
Researcher Ramiro Joly-Mascheroni, a psychologist at Birkbeck, University of London first tested the phenomenon in his dog, a Labrador. Immediately upon yawning himself, Joly-Mascheroni's dog immediately yawned. And sure enough, tests on friends' pups showed similar results.
For the new study, the furry cast included a wide range of dog breeds from a Greyhound to a Staffordshire Bull Terrier to a Dalmatian. In total 29 dogs went through two testing scenarios each lasting five minutes, one in which a human (not the owner) called the dog over and while keeping eye contact with the dog he or she would act out yawns that included the vocal portions.
In the non-yawning scenario, the human went through similar motions, except he or she didn't yawn vocally and instead just opened and closed their mouths.
During the yawn sessions, 21 dogs (or 72 percent of them) yawned, while no dogs yawned during the non-yawning scenario. That's compared with 45 percent to 65 percent found from past studies in humans and 33 percent found for chimpanzees (in chimp-to-chimp studies).
In addition to yawning, the dogs showed similar reactions to human yawns. "In the yawning condition, we found the dogs reacted pretty much in the same way," Joly-Mascheroni said. "They all acknowledged the yawn in some way either by dropping their ears or turning their heads away."
Catching the Z's
The researchers aren't sure why dogs catch the yawns from us. In fact, scientists don't yet understand contagious yawning in humans.
"There are theories that seem to think that we used to transfer this information of 'I am tired' by yawning when we didn't have language," Joly-Mascheroni told LiveScience.
In this same way, humans could be transferring sleep info to dogs. "It would be interesting to find out what other information we transfer to dogs or to any other animals that we are not aware of," he added.
In past studies, research team member Atsushi Senji, also of the University of London, has shown a possible link between empathy and contagious yawning in autistic children, the researchers said. Autism is a developmental disorder in which individuals often show impaired social interaction, problems with communication and a lack of empathy, according to the National Institute of Neurological Disorders and Stroke. This previous research showed that autistic kids don't "catch" yawns from others, Senji said.
And so the new results in dogs, published online in August in the journal Biology Letters, could mean man's best friend has the capacity for a basic level of empathy.