Yawning may have the dubious distinction of being the least understood common human behavior,” UMBC’s Bob Provine told NPR’s Morning Edition this spring. Yawns can be triggered by boredom, fatigue, hunger, or stress. Although multiple theories attempt to define yawning’s purpose, researchers have yet to settle on a unified explanation of why we yawn.
Provine, professor emeritus of psychology at UMBC, says, “[Yawning] stirs up our physiology, and it plays an important role in shifting from one state to another.” Another study cited by NPR supports the changing-state theory, finding “that yawning has a similar impact on the brain as a dose of caffeine.” Provine mentions that athletes about to compete, musicians about to perform, and military about to enter combat also yawn at higher rates than expected.
However, other studies have not found yawning to have an arousing effect. Rather, their results suggest yawning is important for social bonding. That theory is strengthened by the fact that yawning is contagious—and not only among humans.
“Until the last few years, the feeling was that contagious yawning was unique to humans,” Provine told NPR, but recent studies have found that dogs and chimpanzees also yawn contagiously. Dogs even yawned more often when humans around them yawned, potentially contributing to the emotional bonds people form with their canine companions.
Provine has also been consulted recently for his expertise on another primal vocalization: laughter. In The Trumpet, he shared that his research has found laughter to be most common in “situations of emotional warmth and in groups,” suggesting laughter, like yawning, may contribute to social bonding.
In The Atlantic, Provine commented on how appropriate it was to include laughter on the “Golden Record,” which was launched into space in 1977 intended for discovery by alien life. “Laughing, like crying, is a human instinct. It’s not under conscious control,” he told The Atlantic. “Whereas crying is a solicitation of caregiving, laughter is the signal of play. It is the sound of play, literally.”
Prior to the most recent Atlantic piece, Provine discussed his two decades of laugher research in depth for a popular video produced by the publication, “Why We Laugh.”
Read more of Provine’s recent media on yawning and laughter:
Why is yawning contagious? (Mental Floss)
A good laugh (The Trumpet)
Image: Dog yawning. Photo by Nate Steiner, via Flickr, public domain.