Yawning has always been a mystery. Aside from being proven contagious, researchers have revealed that yawning longer also means having a bigger and more complex brain.
A study released by the Royal Society Publishing in early October 2016 had researchers watching YouTube videos of 205 full yawns of 117 creatures from 24 different species, including elephants, dogs, lions, foxes, monkeys, hedgehogs, humans, and many others. (How cute is that?) They then linked the length of yawns to “brain weight, EQ, and cortical neuron data,” and found that the bigger a creature’s brain, the more likely it was to yawn longer. Humans clock in the longest yawns, which average six seconds.
So that proves your smarts, but what exactly do yawns do to you brain?
According to a feature on WebMD, yawning increases blood flow to your head and neck, while “[forcing] downward flow of spinal fluid and blood from your brain.” It’s also theorized to help cool your insides, including the surface of your grey matter. Some researchers who are still on the fence about this theory offer another explanation: That yawning is an unconscious communal action which strengthens “social competence and empathy.”
“In my view, the most likely signaling role of yawning is to help synchronize the behavior of a social group – to make them go to sleep more or less at the same time,” explained Christian Hess of the University of Bern in Swizterland in an article by BBC.
Whatever the purpose of yawning is, at least you know that this impulse means that your brain is just the right size.