Why are yawns contagious? All the theories in one super-cute video

It's probably morning where you are, and you may find yourself surrounded by yawning coworkers — which makes you, in turn, break into a yawn. Why does someone else's yawn make you yawn? This cute video from TED-Ed offers a few theories, along with the science of yawning. » 11/08/13 7:07am 11/08/13 7:07am