Letters
By Science News
Yawn and open your ears
I read with interest your article on yawning (“Yawn,” SN: 5/7/11, p. 28). Over the years I have formulated a private theory on at least one of the reasons why we yawn and would like to share my speculations with your readership.
My insight essentially began when I noticed that immediately after yawning my hearing acuity noticeably improved (sometimes dramatically so) for at least a short period of time. I have observed this phenomenon in myself on multiple occasions over my life span from adolescence to my current age of 67 years.
I believe the process of yawning opens the eustachian tubes which equalizes the pressure in the middle ear which, in turn, allows for improved sound conduction through the ossicles into the inner ear. This pressure adjustment should also affect the back pressure on the membrane of the round window to improve the fine tuning of the cochlear hair cells’ response.
Whatever the details of the mechanism, a case can easily be made that improved hearing is an advantage for both predator and prey that would be differentially favored by natural selection. As to why yawning should be contagious and why it should tend to occur when one is drowsy or bored: If group members are signaling to each other unconsciously through their yawns to awaken and prick up their ears, this could confer a survival advantage not only to the group as a whole, but to each individual and thus to their “selfish genes.”
Robert Gorkin, via e-mail