Most Societies Completely Misunderstand Yawning
In many societies, yawning often gets a bad rap. We stifle yawns in conversation lest our companions deem us uninterested. We swallow them at work meetings so bosses don't think we're unengaged.
To Cara Santa Maria, a PhD student in clinical psychology, award-winning science communicator, and co-host of The Skeptics' Guide to the Universe podcast, this seems rather backward.
"Yawning did evolve as this social cue… We think of it as a way to communicate to our kin that we’re safe, that we’re settled, that we can relax," she said on a recent podcast episode.
"Yet socially, yawning is considered rude," she stated, bemused at the apparent contradiction.
She's right. It doesn't make any sense.
Her co-host, Yale neurologist Steven Novella, agreed.
“There’s evidence that yawning is more of a waking up signal than a ‘sleepy’ signal," he commented. "People do it more when waking up than when going to sleep."
Most people tend to view yawning one-dimensionally – as a sign of fatigue and particularly boredom. Scientific research has not evinced this narrow notion, instead illuminating other potential functions.
Santa Maria touched on one of them. Yawning, it seems, is a form of social empathy, a subtle communication that we're feeling what our friends feel. This is why yawns are contagious, and seem to be more contagious amongst friends and family compared to acquaintances or strangers. This infectious quality doesn't just apply to humans, but to all sorts of animals. For example, a recent study found that yawning seems to help lions synchronize their movements.
Moreover, as Novella noted, yawning is theorized to help keep animals alert, and to remind conspecifics to do so as well.
One of the most intriguing explanations for yawning is that it helps us thermoregulate, often to keep the brain cool.
"Serotonin is an important neurotransmitter in the regulation of skin blood flow, and the thermoregulation this blood flow does. Increases of serotonin have been shown to increase body and brain temperatures, a change that causes the body to trigger more yawns, in an attempt to cool itself," Ada McVean wrote for the McGill Office for Science and Society.
Further support for this idea comes from an interesting correlation: animals with bigger brains tend to yawn longer.
Thirty-five years ago, Robert R. Provine, a neuroscientist and Professor of Psychology at the University of Maryland, Baltimore County and a pioneer into yawning research, wrote that "Yawning may have the dubious distinction of being the least understood, common human behavior." Thanks to his work and the scores of research it inspired, we now know a lot more about yawning. The primal act doesn't deserve its poor reputation.