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 ...

Are you yawning yet? Thought so. Infectious yawns are as frustrating as they are intriguing. Sometimes it's enough to need to see someone yawn, hear them talk about it or even read about it for ...