The Mysteries of the Yawn

Have you ever noticed how addictive yawns seem to be? Even just the mention of a yawn can sometimes cause a chain reaction of stretched jaws and deep breaths. Chances are, you will actually yawn while reading this post!

So, what’s behind the mysterious science of the yawn?

First, let’s take a look at the basics of yawning. It all starts with the fact that a yawn is an involuntary action. We know this because scientists have observed fetuses yawning while in utero during pre-natal health studies.

During a yawn, many parts of the body are put into action. Your mouth opens and your jaw drops, allowing for the highest intake of air into the lungs. The abdominal muscles are thrown into overdrive, and the diaphragm is pressed down from its normal place as the air that is taken in expands the lungs until they are full, before blowing some if it back out.

It’s a common belief that yawning is a result of being drowsy and relaxed, but scientists have found that your heart rate can increase by up to 30% when you are in the process of yawning, and they have found that it is actually an indicator of physical arousal.

Even though it’s believed that humans have been yawning for as long as we have existed, the simple truth is that no one knows what causes us to yawn, but scientists do have some theories as to what causes the involuntary action.

  • The Oxygen Theory: Proponents of this theory believe that our bodies initiate yawning to draw in more air into our bodies, and replenish our oxygen levels when there is a buildup of carbon dioxide. This theory helps to explain why people tend to yawn more when they are in a group, since the more bodies there are around, the higher the level of carbon dioxide being released into the air.
  • The Caveman Theory: There are some scientists that believe that yawning is a holdover from our ancestors, who used yawning as a means of intimidation. The baring of the teeth during a yawn was a way to indicate a warning to others that they should keep their distance from the yawner.
  • The Cooling Theory: Researchers have recently presented the theory that we yawn in an effort to cool our brains down. Strange as that may sound, there have been studies that show those with a cooler head are able to think and reason more clearly than those that have a higher temperature due to illness, exertion, or environmental heat sources. The believers of this theory think that people may yawn in a subconscious effort to cool themselves so they can sharpen their focus.

Although we don’t as of yet why we yawn, we do know that it is something that all vertebrates take part in, even fish! But only humans, chimps, and dogs have been shown to find it contagious.