Although scientists have yet to determine the exact function of the yawn in humans, some research suggests that yawning was used in our evolutionary past as a communication signal of some sort. Perhaps it was a means of showing off ones large teeth in a threat display or simply a way to signal to everyone that it is time to move on in search of greener savannas. We tend to yawn more when we are bored, but boredom alone does not account for many of our yawning incidents. Athletes yawn while working out, babies yawn while in utero, and we often yawn in response to seeing, hearing, or even thinking about yawning. This “contagious yawning” phenomenon was of interest to researchers at the Yerkes National Primate Research Center, who set out to better understand why chimpanzees yawn when they see other chimpanzees letting out their ho-hums.

In the study, 23 chimpanzees (Pan troglodytes) from two separate groups were allowed to view videos of other chimpanzees either yawning or just simply hanging out. (Check out the video below…even chimps can’t seem to  turn away from the i-phone!)  As expected, chimpanzees routinely yawned in response to seeing other chimps yawn, but the interesting part was that the chimpanzees yawned more when watching their friends and family yawn than when they watched strangers yawn. What does this mean?

The researchers think the results support the idea that contagious yawning is related to empathy–or the ability to recognize and share the feelings of others.  Humans tend to have more empathy for our loved ones and people more like us than we do for complete strangers or people not like us. So, the more empathy we have for someone, the more empathetic behaviors we show them. If yawning is a symbol of empathy, then we would expect close group members to contagiously yawn more often around each other.  Indeed, it has been shown that in other primates (ex: gelada baboons), the closer the social bond between two monkeys, the more they contagiously yawn around each other.

So, a fun experiment for you amateur primatologists would be to let out a big yawn and then note which people tend to yawn the most in response. Are the strangers that yawn back at you more empathetic individuals than others?  If your friends don’t yawn back, are they really your friends??? What else could explain the differences in amounts of contagious yawning?

Reference:

Campbell MW, de Waal FBM, 2011 Ingroup-Outgroup Bias in Contagious Yawning by Chimpanzees Supports Link to Empathy