Yawning is a natural, involuntary process. In simplest terms, it can be defined as the wide opening of the mouth due to lack of oxygen, tiredness, or sheer boredom. A lot of air is inhaled involuntarily when a person yawns and an average yawn lasts for 5-6 seconds. It is believed that a baby starts yawning while still in the womb. Apart from human beings, animals like the jaguar, monkey, seagull, hippopotamus, parrot, etc., also yawn.
When someone around us yawns, we have an urge to yawn. It is believed that yawning is contagious. It is observed that babies and infants (under 4 years of age) do not yawn if anyone around them yawns. On the other hand, it is very contagious in adults. Adults tend to yawn when they see others yawning, when they read about yawn in a book, or even when they hear a yawn on the telephone. This is true even in case of deaf and blind people. Peculiarly, yawning is also contagious in case of animals. But, autistic and schizophrenic people do not yawn when observing others doing it.
Why Do We Yawn?
You may have observed that when a single person in a group yawns, others suddenly get an irresistible urge to yawn. People may try to stifle it, but, the urge that makes them yawn is unconscious. There are a few theories that help in understanding the reason behind it. As mentioned above, it is found that people yawn because of lack of oxygen. Therefore, when in a crowd, many people yawn in order to inhale more oxygen. However, it is harder to prove it scientifically.
Some researchers believe that yawning in a group dates back to the ancient times when Stone Age men used to yawn together in order to intimidate others by showing their teeth. On the other hand, some researchers believe yawning to be a sign of tiredness and boredom. People in ancient times would yawn when in a group to signal each other that it was time to retire or sleep. Secondly, it was believed in some clans that people who yawned were less energetic, and hence, were protected and sheltered by others.
Some scientists believe that yawning is based on the reaction of certain processes in our brain. They found that there is a tiny part in the brain which controls all facial expressions. Therefore, it is believed that when a person sees another person yawning, this part becomes active and responds in the similar way. The entire process is involuntary. On the other hand, strangely, yawning is also considered to be a form of showing empathy or belongingness. None of these theories are proven yet.
Yawning is surely contagious. Although there have been several researches and surveys undertaken to prove it, there is no satisfactory scientific reason discovered yet.