Pretty much everyone yawns—but only humans and a handful of intelligent animal species are capable of contagious yawning. Why our family members, significant others, and even household pets seem to catch our yawns has boggled minds since Aristotle. Studies have shown correlations between contagious yawning and closeness in relationships and research suggests women, who tend to score higher on empathy tests, may be more susceptible than men. So the dominant theory is that contagious yawning facilitates empathy and social bonding. The question is how, and why.
“Yawning may have the dubious distinction of being the least understood common human behavior,” Robert Provine, professor of psychology and neuroscience, told NPR. Indeed, despite being a near-universal part of the human and animal experience, we’re still not even sure why we yawn in the first place. Physiological theories that yawns are a way of sucking oxygen into the bloodstream when we’re tired have been replaced in recent years with theories that yawns may function as cooling mechanisms for the brain. And none of that even begins to account for contagious yawning.
But even as we struggle to figure out why our bodies yawn, researchers are beginning to crack the code behind contagious yawning. In support of the hypothesis that yawning is a social behavior, researchers demonstrated in 2009, 2010, and again in 2013 that autism impairs the ability to catch yawns, and that psychopaths are similarly immune. Meanwhile, kids do not seem to respond to contagious yawning until around age 4, a key stage of social development. Chimpanzees, animals that also have complex social structures, also appear to yawn contagiously, and, interestingly, dogs can catch yawns from humans but not other dogs—almost as if they know who their best friends really are (people with food).
Does this mean that boredom, exhaustion, and all the other life stressors that make faces go “ahhhhhh,” actually bring people together? Perhaps, but not every expert. A new study, due to be published in the June 2017 issue of Adaptive Human Behavior and Physiology, asserts that decades of research about yawns being contagious could be bogus.
“The observation that yawning is contagious may have arisen as a consequence of our tendency to see patterns and causation where none exists, to misinterpret the clumpiness of randomness as something else,” Rohan Kapitány, a postdoctoral fellow at Oxford University and author of the new paper, told Slate. By modeling the spread of yawns through a crowd, Kapitány found an error rate of 48 percent. When he tried to recreate this with 79 students, he observed that some yawns were contagious, but interprets this as more of a learned behavior than anything else.
Nonetheless, Kapitány is in the minority. Most experts remain pretty much in agreement regarding our ability to catch yawns, and that empathy and bonding are important pieces of the puzzle. “As far as I’m concerned, there’s no debate over whether yawning is contagious in humans,” Andrew Gallup, a leading yawn scholar, told Slate.
And if contagious yawning helps bring the family closer together, perhaps it’s worth it. Put on a boring movie. Listen to a lecture. Stay up late, or just let your kids tire you out. Embrace your next yawn—and share the love with your family.