A yawn is defined as a reflex act of opening one’s mouth and inhaling deeply. We yawn most often when we are tired or when we’re bored. But we also always yawn when we see someone else doing it. Why? People say we can’t help it – it’s contagious! But what really triggers this involuntary tendency? According to studies, yawning when others do is a sign of empathy and a form of social bonding. And believe it or not, we’re not the only species to exhibit these contagious behaviors. A new study published today in the journal PLOS ONE shows that wolves may also be susceptible to yawn contagion.