What is a yawn?

Yawning is characterized by the gaping of your mouth accompanied by a long inhale of air followed by a shorter exhale. It was once believed that people yawned to increase oxygen levels to the brain, but that has been disproven by more recent studies.

There are a lot of rumors and theories about why people yawn.Yawning is a powerful phenomenon that doesn't only affect humans, but a large number of other animals as well, such as chimpanzees, baboons, dogs, guinea pigs, snakes, and even fish. Yawning is a function that serves many different purposes, depending on the animal, but for humans that purpose is still not completely known.

Many theories have sprouted over the years about yawning. The Empathy Theory explains that you are more likely to yawn in reaction to someone else based on your relationship with that person. This suggest that yawning is based on a in-group-out-group bias, so you would more likely yawn from seeing your mother yawn than if you were to see a random person on the street do it. This would also support the study that found psychopaths are extremely less susceptible, if not immune, to contagious yawns because of their lack of empathy.

Other recent theories suggest that yawning is more of a thermoregulatory mechanism to keep the brain cool and functioning at a high level. Many things can cause the brain to increase in temperature, such as stress and anxiety. This would explain why some athletes yawn before an event, or why you might yawn when you're in a stressful situation.

There are many theories about why people yawn, whether it be just a bodily function or a social effect, but the reasons are still not completely known. Only time, and more research, will tell.