The Yawn of Man

April 13, 2011

Brit Trogen

It's morning; you've just woken up. Someone nearby takes a big, gaping yawn.


It's contagious, right? So contagious that you may even catch it just by reading about it. Until recently, contagious yawning was a bit of a mystery, but with the discovery of mirror neurons it has now been linked, both theoretically and empirically, to empathy. Just as certain areas of the brain are activated in response to feeling pain and seeing someone else in pain, they are also activated during infectious yawning.


Despite the fact that it sounds like a purely altruistic emotion, empathy conforms to an "in-group" bias in humans. People who are seen as belonging to the same social group (usually as defined by race) will activate a stronger empathic response than those who don't. If you were to watch a needle going into the hand of an in-group member, you would react more strongly than to a needle penetrating the hand of an out-group member. And perhaps most interesting of all, in studies where a hand is artificially colored purple, removing race cues, empathic responses score higher than the out-group, giving a result of in-group > purple > out-group.


Which brings us back to yawning. Humans aren't the only ones to experience the yawn response, as dogs, baboons, macaques and chimpanzees have also been found to "catch" the yawn. But it's chimps that offer the most insight into the empathy connection, particularly as it relates to social bias. In a recent study of 23 adult chimps from two separate groups, chimps were shown videos of familiar or unfamiliar individuals either yawning or at rest. In both groups, the chimpanzees yawned about 50% more frequently watching members of their own group yawn compared to strangers. In other words, they seemed to favor members of their own social group in their yawn response.


The ingroup-outgroup bias controls your yawns! But don't beat yourself up about it. Chimps live in smaller and more distinct communities than humans, with all strangers viewed hostilely as an out-group. Humans, by contrast, don't necessarily consider all strangers to be outsiders, and have fewer boundaries towards feeling empathy towards them.


You should probably be pretty liberal with your yawns from now on, though, just to be safe.



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