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Why Do We Yawn?

So natural a thing, maybe akin to breathing! But yet the thought flutters around - What is yawning really about? Read on for some interesting theories on why do we yawn.
We all yawn. And probably it would've been relegated to the same category of 'We all breath'... but for one thing. And that is the conditions in which we yawn. Of these there are many. Some believe that we yawn when we are tired; others maintain a firm belief that boredom is something that causes yawning. But probably the most interesting and baffling situation of them all is that we yawn when we see others doing the same. This results in the need to question - why do we yawn when others yawn? Is our body actually trying to tell us something? Or is it all in our minds?

What Makes us Yawn: Theories

Theory # 1
The most common and accepted explanation for yawning is that it comes about as a result of tiredness or boredom. Scientists say that when we are tired, bored or sleepy our breathing becomes slower, such that the required amounts of oxygen are not generated in our body, which are essential for proper functioning. Along with that, it leads to an increase in the levels of carbon dioxide gas. To correct this situation, the brain induces a yawn.

A characteristic yawn will lead to a wide opening of the mouth and dropping of the jaw - so that the maximum amount of air can be taken in and fill the lungs. This is then followed by a slow exhalation, so also flexing of your abdominal muscles, expanding of your eardrums and your diaphragm being pushed down. When the brain needs a wake up call, it will induce this action so that the long inhalation will lead to the filling of the lungs to its capacity, dispelling it of the stale air, increasing the heart rate and leading to a revival of senses.

Points to Ponder: If one is to believe that the increase of carbon dioxide levels and decrease of oxygen levels in the human system is what propels the brain to induce yawning (for the purpose of correcting the levels) - then a study done by Dr. Robert Provine proves otherwise. In this study he made volunteers breathe air containing different types of gases in different ratios. And when the levels of carbon dioxide in these gases was increased by 3% and 5% none of them yawned more than normal. Even though it would mean that the volunteers would inhale CO2 in greater levels), thus refuting the hypothesis. It is a known fact that Olympic athletes yawn before the start of an event - does that mean that they are bored or tired with the entire world watching them? So also the fact that we yawn when we wake up in the morning - does it mean that we are still tired?

Theory # 2
The second theory states that we yawn when the brain temperature rises. This is because our brain is like the computer which works best in cooler conditions. Therefore when the temperature in the brain rises, we yawn, thereby inhaling cool air which leads to lowering the temperature, which in turn leads us to work more efficiently.
This theory can be proved true. In a study conducted at the University of Albany in New York, 44 students were shown a video of other people yawning (which automatically induces yawns). These students then held a hot pack to their forehead which resulted in the rising of temperature in their brain. It was found that they yawned more than the normal levels. These same students then held a cool pack to their forehead thereby lowering the temperature - in this case they found that their levels of yawning were reduced to less than the normal levels.

They also found that breathing through the nose as opposed to by the mouth reduced the yawning levels because the nasal cavity vessels send cool blood to the brain.

Why Do We Yawn When Others Yawn?: Theories

Probably the most important question related to this issue is what makes us yawn when we see others yawning? Why is it so contagious that even when we aren't tired or bored or sleepy we end up yawning when we hear or witness someone doing the same, even though it is through television?

The Communication Theory
Researchers believe that yawning is contagious because it is an innate form of communication. In earlier times when language had not developed, our ancestors used signs and signals to communicate with each other. In that era they stayed in large groups and the safety and survival of the group depended on how well they could communicate their emotions with the other. For example, when there was danger lurking about, they would bare their teeth which was taken as a sin of aggression and showed the enemy that they were ready to fight. That is how the smile as we know it today, developed. Similarly, yawning would have been a signal to the others that a person was tired and it led to a group yawn so that after yawning they were all vigilant and there were better chances of survival. Or that they were tired and was therefore time to sleep. This theory could be taken to be true because many animals, fish and snakes yawn too - which would only prove that it was used as a form of communication.

The Mirror Theory
This theory says that we yawn when we see others yawn because of specific 'mirror neurons' in our brain that cause the mirroring effect. When a person yawns it causes these mirror neurons in the brain to fire and it leads to a yawning reaction.

The Empathy Theory
This theory suggests that the part of our brain which comprises the 'empathy hormones' is the same part that gets activated when we yawn. Empathy literally means - putting yourself in someone else's shoes, understanding what they are going through and identifying with their perspectives.

The study suggests that when we see someone else yawn our empathy hormones are activated, it is our way of understanding what the person is going through. That is why we 'catch' a yawn more easily when we witness someone close to us yawning as opposed to an unknown person. So also, not all people will 'catch' a yawn - some will do so more times than others. This would mean that the people who invariably yawn when others do are more empathic in their lives - which would amount to a social skill.

This theory can be proved by way of the inability of the people who suffer from Autism Spectrum Disorder to succumb to empathy yawning. Disorders of autism spectrum are mental disorders which lead to abnormalities in social interactions and communications, which means that people who suffer from this disorder are unable to interact and carry out normal social interactive behaviorism like the others. From this it would be clear that their empathy levels will be quite low. And since the theory says that contagious yawning is brought about by empathy, it would show why those suffering from this disorder do not show empathy yawning either.

Even though you know what yawning is all about, there is little to no chance that whenever you yawn, people will be empathetic. So the next time someone accuses you of being bored when you yawn, just say you were trying to get in more oxygen to your brain so you could pay better attention to what they were saying. So then, how many times did you yawn during this article? Don't worry - I won't take it personally.
By Rujuta Borkar
Last Updated: 9/27/2011
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