Add Yahoo as a preferred source to see more of our stories on Google. So why exactly do we yawn? And why is it nearly impossible to stifle a yawn when someone does it in front of you? Let’s find out.

Humans aren't alone when it comes to yawning — all vertebrates do it too, including fish, amphibians, reptiles, birds and mammals. But why? The "evolutionarily ancient" act of yawning likely serves a ...

The average adult yawns about 20 times a day. But why? Surely we can’t all be that tired. The truth is, the science behind yawning is more complex than just a few hours too little sleep. Even more ...