Why Do People Yawn?

Yawning. Even though it’s one of the most universal behaviours, yawning is still a mystery to scientists. And humans aren’t the only ones who yawn – dogs yawn, cats yawn, even snakes and fish yawn. For humans, yawning starts even before we’re born – it’s been observed in fetuses as early as 11 weeks. One of the most fascinating things about yawning is that we can’t yawn on command, but yawning is contagious. Seeing someone else yawn – even reading about yawning – makes most of us want to yawn. Go on, I won’t be insulted if you want to take a yawning break now. The average human yawns about 8 times a day – or a few more for those reading this post.

And the thing is, the harder we try to stop ourselves from yawning, the more likely we’ll be to yawn. So the question is: why do we yawn – what purpose does it serve? Well, there are lots of theories on that.

Yawn Theories

One is that we yawn when too much carbon dioxide builds up. Another theory is that we yawn because we’re bored. And while it’s true that we do yawn when we’re bored, we also yawn when we’re… not bored.

There’s even one theory that yawning evolved among our ancestors as a mechanism to intimidate others by baring our teeth. More recently, research has focused on the brain itself. Scientists found a link between the length of a species’ yawn and the size of the brain and the amount of cortical neurons it has. Humans, with big brains and lots of neurons, yawn for over six seconds. Mice, on the other hand, do cute little 1 second yawns. You know what they say…the bigger the brain, the longer the yawn.

In 2007, psychologist Gordon Gallup published a study proposing that the purpose of yawning is to cool the brain, as he found that participants yawned less when their brains were cooled with cold towels against their foreheads. What purpose would this serve? Our brains, which consume 40 percent of our metabolic energy, can easily heat up, and, as Dr. Gallup says, a cooler brain is a clearer brain.

Another yawning researcher, Dr. Robert Provine, has found that we yawn when we’re changing physiological states: going from wakefulness to sleep, from sleep to being awake, from being bored to being alert and vice versa. This would explain why Olympic athletes often yawn before their events, or why paratroopers will yawn right before jumping.

Why is Yawning Contagious?

So, that’s all super interesting, but it doesn’t explain the most fascinating part of yawning – the fact that yawns are contagious. It’s almost impossible to see someone yawn and not feel a little bit of a yawn coming on yourself. First, not everybody is susceptible to contagious yawns – only about 60 percent of us are. And, though yawning is seen throughout the animal kingdom, only humans, primates, and dogs yawn contagiously.

For years, it was thought to be connected to empathy. People are more likely to yawn contagiously if they know the person that’s yawning, and primates will contagiously yawn more among members of their own group. But recent research casts doubt on the empathy theory. In fact, the only independent variable that influenced the rate of contagious yawning was age – we yawn less contagiously as we get older.

So why is yawning contagious? For the temperature theorists, it would be a social cue – if something has made one person need to think more clearly by cooling down his or her brain with a yawn, you might need to do the same. For Provine, it could mean a social signal that, when we’re changing states, we might need attention from those around us.

So why do people yawn? Is it really because they are trying to get oxygen, or is it maybe the fact that they are just bored? There are many different theories on why people yawn, but funnily enough, scientists have not been able to prove anything.

The following theories, have been the historical explanations of yawning.

Firstly, many people believe that yawning is due to being bored, or simply due to inactivity of the body. However this theory has no proof, so we do not know that this is the case, as scientists have not been able to prove that it has anything to do with the psychological state of boredom.

The second popular myth to do with yawning, is that it comes from a lack of oxygen, and is a subconscious mechanism in order to make the person breathe more and get more oxygen. However, this theory has been tested by scientists, and has been proven to be incorrect as the difference between people who were deprived of oxygen and the amount of times they yawned, and the amount of times that people who would not deprived of oxygen yawned were insubstantial.

One final theory, is that yawning is an evolutionary bodily action, similar to how a dog bares its teeth when it wants to show anger to another dog or person. But again there is no evidence to suggest that this theory is correct.

In conclusion it is unknown why people Yawn.

In any case, congratulations if you’ve made it all the way through this without yawning. In one study, 88 percent of those instructed not to yawn yawned within 30 minutes. You’ve got 25 minutes left – seriously, don’t yawn!