Scientists Just Got Closer to Understanding Why Yawns Are So Darn Contagious

A large number of animals are yawning right now all throughout the planet. Maybe they're tired and want to sleep; maybe they're hot and bored.

But one thing is certain: just thinking about yawning makes us want to open our lips and take a deep breath. (I've already repressed a few yawns, and I'm only halfway through.)

While scientists are pretty sure in their understanding of the physiological function of yawning, it is still unknown why it is particularly infectious among social animals.

The answers might already be strewn across the material we've accumulated on animal neuroscience, psychology, and social behavior, as is often the case in science.

To figure out what the data means, evolutionary scientist Andrew Gallup of the State University of New York Polytechnic Institute in the United States combed through previous studies and combined the findings into a single explanatory model.

Yawning may be a technique for groups of animals to coordinate their behavior and increase collective attentiveness, according to Gallup.

Yawning, like the other strange gasping reaction, the hiccup, appears to have no evident purpose. Our jaw muscles clench, our diaphragm flexes strongly, and we take a deep breath of cool, clean air when we're relaxed (typically when we're tired).

It was once thought to be a way of replenishing oxygen or releasing carbon dioxide, but it now appears to be more about controlling blood temperature to keep the brain cool.

Almost everything with a backbone uses this method of thermoregulation, thus it must be significant. Yawning is a function that has developed in our shared ancestors from mice to monkeys, fish to flamingos over a long period of time.

Why would one nice yawn merit another if that's the case? Individuals generating subsequent yawns — a habit so infectious it may traverse species borders – would imply an advantage to a group of brains cooling down together.

This might be close to the mark. That advantage, according to Gallup, is a physical wake-up call that helps compensate for people's lethargy.

Yawning occurs as we transition from one activity to another, whether it's relaxing for a nap or waking up after a full night's sleep. We also yawn while expecting a change, causing or sustaining alertness in situations where stimulation is improbable.

A fast 'brain chill' from the infusion of fresh air might be the ideal approach to shake it up in preparation for a potential task without putting it into fight-or-flight mode.

In this perspective, having a few pals watch your back as you nod off or sleepily slog towards a potentially sticky scenario would not be a bad idea. A group of brains can take up the slack by passing that yawn around, increasing attentiveness while one or more members of the group exhibit indications of altering state.

Gallup remembers an experiment he did last year in an interview with Tess Joosse of Science Magazine.

"We showed people arrays of images that included threatening stimuli – images of snakes – and nonthreatening stimuli ­– images of frogs – and timed how fast they could pick out those images after seeing videos of people yawning or moving their mouths in other ways," Gallup added.

"After seeing other people yawn, their ability to identify and detect snakes, the threatening stimuli, rapidly improved. However, following the observation of yawning, frog detection was unaffected."

As far as explanatory models go, it's a compelling concept that begs to be tested. Uncovering the secrets of a good yawn might teach us a thing or two about the delicate kinds of communication that exist inside and across social species, including our own.