This is

This is Scientific American 60 Second Science.

I'm Christopher Intagata.

Not many scientific studies begin like this.

Many hours of watching YouTube clips,

trying to find as many yawns as possible.

But for Andrew Gallup, an evolutionary psychologist who studies yawning at the State University of New York,

it was all in a day's work.

Gallup says yawns have traditionally been known as a sign. New York, it was all in a day's work.

Gallup says yons have traditionally been known as a sign of sleepiness or boredom.

A recent evidence suggests that yawning may function to promote brain cooling.

The idea being when you breathe in deeply the

incoming air slightly cools the brain and stretching the jaw increases blood flow

to the brain too, another cooling factor. The reason we do it at night? At nighttime when we're

about to go to sleep our brain and body temperatures are at their highest point during

the day and that's when we see highest frequency of yawning. And so Gallup and his colleagues found themselves hunting

for cat videos on the internet.

Along with clips of dogs, foxes, elephants, gorillas, hedgehogs, squirrels, rats, even walruses, yawning.

They timed all those yawns and then compared them to each species average brain weight and

the number of neurons in the cerebral cortex.

Their conclusion published in biology letters

was that the length of a yon was a remarkably good predictor of an animal's brain weight

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