The human body is riddled with mysteries, and yawning is no exception.
It's not very flattering — and it's occasionally even considered impolite — but we all do it. And when the urge to yawn strikes, we frequently succumb.
While we typically associate yawning with feelings of exhaustion or boredom, some people report yawning more frequently while exercising or singing. If yawning is not simply a sign of sleepiness or boredom, then why do we yawn?
The most perplexing aspect of yawning is that it appears to be contagious. Indeed, yawning is so contagious that you do not need to see another person yawning to yawn. Occasionally, all it takes is hearing or thinking about a yawn. You may even be yawning as you read this.
Thus, how much of yawning remains unknown, and how much can science tell us?
What Causes Us To Yawn?
Yawns are classified into two types by experts: those that occur spontaneously and those that occur as a result of witnessing someone else do, referred to as contagious yawning.
However, whether spontaneous or contagious, why do we do it at all?
As it turns out, we're not entirely certain why we yawn. However, some theories assert that yawning is beneficial. It can:
Control your brain's temperature
Rejuvenate your body
Increase the amount of oxygen in your bloodstream.
Maintain good lubrication of your lung tissue.
Your brain functions optimally when it is kept at an optimal temperature. When the brain is overheated, for example, cognitive performance may suffer. As a result, your body responds to temperature changes in a variety of ways, including sweating or shivering, dilation or constriction of your blood vessels, and triggering behaviours that cause you to seek cooler or warmer air.
According to the brain thermoregulation theory, yawning is yet another mechanism for cooling your body — specifically, your brain.
However, regardless of whether a physiological reason for yawning exists or not, experts agree that yawning is contagious.
How Come Yawns Are Contagious?
As with the mystery of why we yawn, experts are also unsure of why yawns are so contagious.
What is known is that spontaneous yawning, regardless of the reason, is an ancient, evolutionarily conserved behaviour shared by a large number of vertebrate animals.
However, contagious yawning appears to be restricted to a small number of animals, including humans, non-human primates, and domesticated dogs. Additionally, contagious yawning does not manifest itself in human behavior until early childhood. Taken together, experts believe that contagious yawning may be a higher-order animal-specific social communication tool.
