Why are yawns contagious

It’s a known fact that yawning is contagious among people, but recently researchers have discovered that it is also contagious among chimpanzees. You may not realize it, but the contagious aspect of a yawn is almost an unconscious effort on your part. Seeing someone yawn can trigger a response from you, without you even realizing it!

In recent years, the Finnish government funded a brain scan study which would attempt to determine just why yawning is so contagious. While the search did turn up a few clues, it confirmed what we already know, that yawning contagion is an unconscious reaction. This reaction bypasses all of the circuitry in your brain which controls what happens when you see someone else do something. This type of circuitry is known as mirror neuron circuitry, as it contains a special sort of neuron which fires only when you see someone else do something. These neurons begin firing when you consciously imitate the actions of another person, which is a process that is associated with how humans learn many of their behaviors. However, these neurons seem to play absolutely no roll in yawning contagion, which makes the reason for yawning to be contagious, that much more baffling.
These researchers have found that while seeing someone yawn doesn’t activate these mirror neurons, it does activate a special portion of the brain, which is known as the superior temporal sulcus. However, it was found that this activation was unrelated to any desire felt by test subjects to yawn, so it could be entirely irrelevant to exactly why yawns are contagious.
In addition to the first region of activation, these researchers also found that an area known as the left periamygdalar region was activated. The activation in this region showed that the more strongly the desire to yawn in response to another’s yawn, the stronger the activation of this portion of the brain was in the test subject.
While the implications of this study were vague, one thing does seem clear. The contagiousness of yawning does not rely on any brain mechanisms. The reaction seems to be automatically released and could serve as a very old motor pattern that is left over from human behavior before spoken words.

Aside from the actual physical brain mechanisms which were thought to fire when yawns were observed, many researchers have offered different opinions as to why this contagious reaction exists. Some researchers believe that in early humans, the yawn contagiousness served the purpose of alerting others of their awareness levels, which helped to coordinate sleep schedules among a tribe of humans.

While yawning could very well be a general phenomenon of unconscious signals which are passed between humans in order to synchronize group behavior, this purpose no longer serves any definable reason for being useful in human culture as it exists today. Yawning contagion seems to be a base instinct such as the flight instinct in birds and other animals, and because we are no longer functioning on the same level we were thousands of years ago, yawning contagion has become a useless trait.