And now, in one of the most groundbreaking scientific discoveries of the decade—and perhaps even the century—researchers from the University of Tokyo have discovered that, like humans, dogs yawn contagiously.
Okay, we kid. But in all seriousness, the finding does shed a bit of light on that most mysterious of behaviors, the yawn. Despite years of research, scientists still don’t understand why we do it in the first place. Most believe we yawn to help cool down when our brains are overheated. The fact that yawning is contagious in 60 to 70 percent of people, many argue, is a function of empathy, as people who score higher on empathy tests are more likely to experience contagious yawning.
In the new study, published today in PLOS ONE, the researchers found that more than half the dogs they tested yawned contagiously—and, most interesting, they were more likely to yawn after watching their owner yawn than seeing it done by an unfamiliar human. If empathy truly is at the heart of contagious yawning, these findings could suggest that canines, too, are capable of true empathy.
This isn’t the first study to show that dogs yawn contagiously, but it is the first to get the dogs’ owners involved. The researchers visited the homes of 25 dogs from different breeds (ranging from golden retrievers to labs to chihuahuas) and had their owners sit in front of them, call their name, and then yawn. For a control, they also had their owners simply open and close their mouths, without a yawn’s characteristic jaw-stretching, deep inhalation or long sigh. As a comparison, they also had people that the dogs had never met before perform both actions. (Incidentally, the paper is vague on how they got the owners and strangers to yawn—although, as you might have discovered since starting this post, simply reading about yawning might have done the trick.)
In total, the 25 dogs yawned 22 times after seeing people yawn, and just 5 times after seeing people open and close their mouths. They were nearly three times more likely to yawn contagiously after seeing their owner yawn as compared to seeing a random person do it. This last finding, they say, provides further evidence for the role of empathy in yawning, as dogs are presumably more likely to empathize with their owners than another person.
Why would empathy be the explanation for why yawns are contagious? As social animals, humans often inadvertently copy the emotions and behaviors of those around them, whether it’s a smile or a frown.
Yawns, presumably, are no exception. And if the underlying function of yawning is to dissipate heat and cool the brain down, mimicking the yawns of others would make a lot of sense. “If I see a yawn, that might automatically cue an instinctual behavior that if so-and-so’s brain is heating up, that means I’m in close enough vicinity, I may need to regulate my neural processes too,” Steven Platek, a psychology professor at Georgia Gwinnett College, told my colleague Marina Koren in her recent post on the science of yawning.
Other work has found that chimpanzees yawn contagiously. That research, along with the new finding, suggests that to some extent, chimps and dogs operate based on the same sorts of social cues as we do.