Everyone yawns on a daily basis. We yawn when we wake up, when we are bored or tired during the day, and even when we see someone else yawn. It is universal to the human race, but what causes this involuntary act?
Yawning is still a mystery in some ways. We know that it is involuntary and that it is often caused by fatigue or drowsiness, but scientists have not yet determined if it actually serves a purpose. There are various theories that attempt to explain the cause and purpose of yawning.
One theory is based on physiology. The idea behind the physiological theory is that we yawn to increase our body’s oxygen and release excess carbon dioxide. In one way, this does make sense, but from a different perspective this theory can be disproved, and in fact, has been. A psychologist from the University of Maryland, Baltimore County named Robert Provine conducted a study in 1987 to test this theory. At the end of his study, he came to the conclusion that providing people with extra oxygen did not decrease the frequency at which yawning occurred. He also noted that decreasing the amount of carbon dioxide available to a person did not prevent yawning.
Another theory is based on evolution. Some people believe that many years ago, our ancestors used to open their mouths and show their teeth to others in order to intimidate them. Therefore, some people have adapted this theory and have explained it with the idea in mind that we open our mouths to express that we would prefer a change in activity.
This particular theory does make sense if you think about it in various scenarios. For example, we yawn when we are tired at night right before we want to go to sleep. Perhaps, we are not yawning simply because our bodies are tired, but because we are expressing our desire to sleep. Maybe we yawn on the job or in class because we would much rather be at the beach or at home relaxing in front of the television. We all yawn in the morning as well. Maybe this is our bodies telling us it is sick of laying around and not doing anything and would like to get up and be active again. Who knows? Quite interesting theory though, I must say!
Perhaps our ancestors yawned to express that they agreed with the people around them. Maybe this is why yawning is contagious. Maybe it is our way of telling people that we feel similarly.
Humans are not the only species that yawn. Many animals do as well. Perhaps this is evidence that yawning may be some kind of form of communication, which would support the evolution theory as well.
Lastly, there is the well-known boredom theory of yawning. This theory simply states that yawning is caused by boredom, fatigue, or drowsiness. Yet, there are plenty of times during the day when people yawn, but are clearly not tired or bored at all. Therefore, this theory does not prove much and needs better evidence to support the idea behind it.
Yawning is such a common act amongst humans and animals alike, yet there is so much left unanswered on this topic. Various studies have been conducted and theories have been created, but no one knows for sure the exact reason why we yawn. It still remains a mystery.
Sources:
http://health.howstuffworks.com/question572.htm
http://www.yesmag.bc.ca/Questions/yawn.html
