The Mystery of the Yawn

The story

Warning: this story is dangerous. Not scary dangerous. CATCHY dangerous. Because this is a story about yawning, and simply hearing about yawns can make you do one. If your mouth stretches wide before the story ends, that is not rudeness. That is science happening right on your face.

Here is what makes the yawn so special. You yawn. I yawn. Babies yawn before they are even born, floating and stretching their little mouths. Dogs yawn, cats yawn, fish and birds and snakes all do their own yawns. It is one of the most ordinary things a body can do. And yet, when scientists ask the simple question, WHY do we yawn, something wonderful happens: they cannot fully agree on the answer. The yawn is a genuine unsolved mystery that you carry around with you every day.

It is not for lack of trying. Scientists have studied yawning for years, and they have good ideas. Some think a yawn is a wake-up stretch for the brain, a big slow gulp that stirs up your blood and helps an idling brain snap back to attention, which would explain why yawns love the sleepy times, just after waking and when rest is near. Others found clues that yawning might cool the brain down, like opening a window for a stuffy room, because brains work best when they are not too warm. Each idea has some evidence. None has settled the argument. The mystery stands.

And then there is the strangest clue of all: yawns SPREAD. When you see someone yawn, you become more likely to yawn too. Hearing a yawn can do it. Reading about yawns can do it. Scientists call this contagious yawning, catching, like giggles. Chimpanzees catch yawns from each other. Even your dog can catch a yawn from YOU, one of the few animals that catches yawns across from a different species. Why on earth should a stretch of the mouth jump from face to face like that? Some scientists think catching yawns is connected to the way we feel along with each other, the same fellow-feeling that makes you wince when a friend stubs a toe. It may be a little signal, older than words, that helped groups stay in step. May be. Nobody is certain of that either.

We can peer into the furthest galaxies and read the code inside our own cells, and yet a thing your face has done since before you were born still keeps its secret. Science is not a finished book of answers. It is a great pile of open questions, and some of the openest are hiding in the most ordinary places: in a yawn, in a hiccup, in a cat's purr.

So, be honest. Did one sneak up on you while you listened? If it did, you just felt an unsolved mystery move your own body. Somebody, someday, will finally crack the case of the yawn. It might even be you.