A new study is giving you permission to literally yawn in everyone's face this morning.
Trust me, you're not being rude. In fact, you're actually just showing off your intelligence (OK, I guess that's also kind of rude).
According to the research, the length of your yawn is associated with how heavy your brain is and how many neurons it has.
So, basically, the longer your yawn, the bigger your brain.
In the study, which was published in the journal Biology Letters, researchers watched YouTube videos of various kinds of animals — including chimpanzees, cats, dogs, gorillas, foxes, camels, hedgehogs, horses, rats and much more — and measured their yawns.
Humans had the longest yawns, as our brains weigh the most, at an average of about 3 pounds.
Following us for longest yawns were chimpanzees, horses and camels.
Among the shortest yawners were mice, rats and rabbits.
All that brain power means our big fat craniums need a nice, long breather every now and then.
Andrew Gallup, an evolutionary psychologist and researcher on the study, explained to Academic Minute how yawning helps to cool our brains:
When you yawn, your gaping jaw increases circulation to your skull, pumping warm blood out of your brain. At the same time, inhaling deeply brings a wave of air into your nasal and oral cavities, cooling cranial arteries through convection. These two processes dissipate heat in much the same way that a radiator cools a car engine.
So, contrary to popular belief, we're rarely yawning out of boredom or exhaustion. Technically, in any context where your body is warmer than it usually is, it makes sense for you to yawn.
Interestingly enough, though, “yawning may have the dubious distinction of being the least understood, common human behavior," Robert Provine, a professor of neurobiology and psychology at the University of Maryland, told BBC.
We know surprisingly little about why we yawn, but this most recent research helps shed a little more light on this abstruse — but still very common — human behavior.
So, there's no need for you to take it personally if people yawn in your face today... that is, unless they're purposely throwing their intelligence in your face.
If that's the case, maybe just yawn back at them and have a yawn-off until one of you passes out.
Citations: People who yawn more tend to be more intelligent (Indy100), Yawn duration predicts brain weight and cortical neuron number in mammals (Biology Letters), Andrew Gallup, SUNY Oneonta – Yawns are Cool (Academic Minute), One of science's most baffling questions? Why we yawn (BBC)