Yawning is one of the most natural things in the world and something that we do even before we are born, but why do we yawn and why is it so contagious?
Theories abound in the medical world as to why humans and some animals yawn. While some scientists believe that it was a method used by our ancestors to warn off enemies by baring our teeth, others see it as nothing more than an involuntary reflex to demonstrate boredom.
Researchers in the US, however, suggest that its purpose is to help keep us awake, hence the reason for it happening when we are tired. Scientists believe that by drawing more oxygen into the body and expelling more carbon dioxide, the brain is cooled down, allowing it to function more efficiently and helping us to stay awake.
Why do we yawn when we see others yawning? Scientists’ theory on contagious yawning is that it is not merely an act of copying others, but that it developed as a means for groups of our ancestors to remain alert and detect danger.
Although it certainly is an unconscious action, the alertness theory does seem to hold water. Watch athletes before they run a race and you will notice that more than one of them yawns, and it has also been observed that paratroopers yawn before jumping, and presumably not out of boredom!