The human body experiences involuntary actions every day, but yawning may be the most elusive.
Nearly every animal with a spine yawns for one reason or another — penguins yawn as a mating ritual, guinea pigs use the action to demonstrate anger and humans yawn for different reasons.

Image: Imgur, GrimReaperPT

AsapSCIENCE made this short, yet informative YouTube video to explain the science behind the human yawn. And you may be surprised, it's not as simple as just being tired.
Scientists believe that humans yawn as a way to cool our brains. Yawning increases blood flow, heart rate, facial muscle use and forces air into your head, which all help cool the brain. Exhaustion and sleep deprivation does increase your brain temperature, explaining why we yawn more when we're tired.
The video also covers the contagiousness and social aspects of yawning, which can be linked to empathy. Mirror neurons also play a large role in yawning. These neurons fire in our brain when we carry out certain actions, watch other people perform the action or simply discuss it.
To prove the point that yawns are contagious, AsapSCIENCE also created this Yawn-O-Meter. How long can you last before yawning?

BONUS: 9 Things You Don't Realize Until It's Warmer Outside

Seriously, is warmth really worth the smell?
Though you'd be willing to overlook a noise complaint if they could be as helpful as the ones in Cinderella.
Or hot chocolate. Or hot apple cider. No more hot liquids.
And just when you were really starting to like the sun ...
With all the manic running and screaming, it's like their parents kept them inside all winter against their will.
Did you always have a birthmark on your arm?
Or factoring in the arctic winds slowing you down on the way to the subway.
Knit shorts will just never be as comforting as fuzzy pajama pants.
By July, you'll be counting the days until winter
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