Yawning is common throughout the animal kingdom, yet we still don’t know what purpose it serves.
Yawning has puzzled scientists for more than two millennium. But could a new theory settle the question once and for all?
Mid-conversation with Robert Provine, I have a compelling urge, rising from deep inside my body. The more I try to quash it, the more it seems to spread, until it consumes my whole being. Eventually, it is all I can think about – but how can I stop myself from yawning?
Provine tells me this often happens when people are talking to him; during presentations, he sometimes finds the majority of his audience with their mouths agape and tonsils swinging. Luckily, as a psychologist at the University of Maryland, Baltimore County and author of Curious Behavior: Yawning, Laughing, Hiccuping, and Beyond, he isn’t offended. “It makes a very effective lecture,” he says. “You talk and then the audience starts yawning. And then you can ask people to experiment on their yawns – like closing the lips, or inhaling through clenched teeth, or trying to yawn with the nose pinched closed.”
It is through experiments like these that Provine has tried to explore a millennia-old mystery: why do we yawn? We all know that tiredness, boredom, or the sight of someone else can all bring along the almost irrepressible urge – but what purpose does it serve the body? When he first started work on so-called “chasmology” in the late 80s, Provine wrote that “yawning may have the dubious distinction of being the least understood, common human behavior”. Nearly three decades later, we may be closer to an answer, but it’s one that has split the field.