Y-a-w-n! Ever wonder why we stretch our mouths wide open now and again in a big yawn? Do we do it because we’re tired? Or maybe bored? Scientists recently discovered that the bigger an animal’s brain, the longer the yawn. What’s the link? Big brains are more likely to overheat, and yawning brings in cool air and stretches muscles around the brain to cool things down. The next time you yawn, don’t assume you’re bored–maybe your brain’s been working harder than you realized.
Did you know? Yawning is common among social animals. Contagious yawning (yawning when someone else yawns–or while reading this post!) appears to coordinate behavior. source
Want to know more? See how long you can go without yawning while watching this Yawn-o-Meter video.