Everyone, including humans and animals alike, yawn. But why do people yawn, basically? A yawn is a reflex action. It causes the lungs to inhale along with simultaneous stretching of the eardrums, that is followed by exhalation. It can sometimes be a powerful non-verbal message, which often has several possible meanings associated with it, depending on the circumstances. There are many questions related to this phenomenon, like what causes it, why it is contagious, etc. The answers to these questions are etched out below.

Vital Information

Yawning is an involuntary action, which causes us to open our mouths wide and breathe in deeply. It is called an involuntary action, as we do it even when we are still in our mother's womb. According to some research, a fetus as young as 11 weeks old can yawn. There are a number of theories associated with what causes it.
  • Physiological Theory: According to this theory, our body induces this theory to draw in more oxygen into the body and remove the build-up of carbon dioxide. This is precisely the reason, why we yawn more often when we are sitting in a large group, as a large group produces more carbon dioxide. Our bodies try to get rid of carbon dioxide, by drawing in more oxygen.
  • Cooling of Brain Theory: There are some studies, which point to the fact, that this phenomenon cools the brain, when it is overheated. The brain is able to function at its best, when it is cool and humans and other animals have evolved adaptations to accommodate this.
  • Evolution Theory: There is a line of thought, according to which, our ancestors started yawning so that the teeth could be visible and the others can be intimidated. There is an offshoot of this theory as well. According to this new theory, this action developed from early man as a signal for us to bring about a change in activities, which are currently being carried out. If one has to talk about it evolutionarily, it was a way of maintaining vigilance or alertness.
  • Boredom Theory: According to some of the dictionaries, yawning is caused due to boredom, fatigue, or drowsiness. It can be taken as a sign to change the current activities.
Although each of these theories justify the causes, they all have their own loopholes.

Why is it Contagious?

Have you ever wondered why you yawn when you see someone else doing the same? About 55% of people do it within five minutes of seeing someone else do the same. According to some studies, this action is a sign of empathy. In the past, it was a method used for signaling each other and what we see now as a contagious reaction is actually a leftover response from human ancestors. The theory of empathy was tested out. The groups, which were tested included autistic and non-autistic children. These studies have shown that autistic children are less likely to yawn after witnessing one, as compared to non-autistic children, as autistic children find it very difficult to show empathy. Although a number species of animals and fish yawn, it is seen to be contagious only in humans and other primates such as apes and chimpanzees.

Connection to Tiredness

Very often, when we are tired, we notice we keep yawning all the time. Same is the case when we are under stress. It is caused as the deep brain temperature is increased, when the person is exhausted or sleep deprived. Yawning cools the brains. It can also be used as a seizure signal, at the same time excessively doing it is an indicator of brain cooling problems.

Hopefully, you have found out your answers related to this action. Would you want to know some facts associated with it? On an average, a yawn lasts approximately for six seconds and the heart rate increases by as much as 30%. Blind people yawn more, when they hear an audio tape of people yawning. Before I end this article, I want you to answer a question sincerely. How many times did you yawn, since you started reading this article?

Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.