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Saturday, 30 May 2015

Why do we yawn?

Arguably the first studier of yawns was the Greek physician Hippocrates nearly 2,500 years ago. He believed that yawning helped to release noxious air, particularly during a fever. “Like the large quantities of steam that escape from cauldrons when water boils, the accumulated air in the body is violently expelled through the mouth when the body temperature rises,” he wrote. (BBC)

For more than 2 millennia scientists have researched this topic and still there is no unified theory on this subject. Remarkably, I even noticed two articles involving 2014 research by Dr Andrew Gallup which basically repeated what Hippocrates had already said 2,500 years ago. Yet, it was considered newsworthy as anything on this topic is viewed with interest. (WSJ, BBC)

Interestingly, there is a lot of symmetry in the causes and the alleged reasons:
- bonding versus attacking / fighting 
- empathy versus contempt
- boredom / sleep versus (sexual) appetite
- oxygen versus carbon dioxide in the brain 
- heating versus cooling of the brain
- air pressure (e.g., ears) versus brain fluids
- individual's dominance / muscle stretching versus (contagious) group behaviour
Sources: Wikipedia, BBC, WSJ, how stuff works, Psychology Today link 1 and link 2

As always, I am struck by the beautiful symmetry that nature provides us with. I wouldn't even be surprised if yawning has - at least - 2 evolutionary reasons similar to laughter. See my April 30 blog on humour and laughter. In the case of laughter there is an evolutionary component and a social / group component that evolved in very different stages of our evolution. 

Most likely the evolutionary component is still to be seen in animal behaviour and in unborn infants who yawn as of the 11th week of the pregnancy. The yawning and muscle stretching of top sporters before important matches (e.g., Olympics) may well relate to displaying the individual's dominance towards his/her competitors. I do see a pattern of interconnectedness in the above mentioned 7 symmetrical causes and alleged reasons. 

The bonding factor is quite interesting in my case. Lately, I have had quite a lot of conversations by phone and those lasted for several hours. I know they lasted for more than 2 hours as my operator keeps on disconnecting me after 2 hours. When she starts to yawn in those conversations, my (involuntary) yawning immediately follows and also vice versa. The first time this happened she said it was a good sign. Obviously, I asked why. She then said it is not good when the other person does not join the yawning. Actually, she was very, very right in that. Research has shown that yawn contagion appears to be primarily driven by the emotional closeness between individuals. Strangers join in yawning either last or not at all.

Comedian Groucho Marx once attended a dull dinner party, which kept him yawning all evening. As he was preparing to depart, the hostess said: “I hope you had a pleasant time, Mr. Marx!” “I had a wonderful time,” cracked Groucho, "but this wasn’t it.”