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Yawning – A Social Disease

Posted by shadmia on August 9, 2008

Yawning is an involuntary action that everyone does. It is not a uniquely human activity. Most lifeforms on the planet yawn: animals, snakes and even fish yawn. However, in humans, it also has one peculiar side effect – it is contagious. Many of us yawn when we see or hear another person doing it, or even read about it or even just think about it. But what exactly is a yawn?

Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We know it’s involuntary because we do it even before we are born. Research shows that 11-week-old fetuses yawn.

There are many parts of the body that are in action when you yawn. First, your mouth opens and jaw drops, allowing as much air to be taken in as possible. When you inhale, the air taken in is filling your lungs. Your abdominal muscles flex and your diaphragm is pushed down. The air you breath in expands the lungs to capacity and then some of the air is blown back out.

Why we yawn, is a subject that has many theories but still leaves a lot of unanswered questions. Complicating matters is the fact that yawning is a largely unconscious activity. We can see someone yawn, yearn to replicate the action ourselves, and do it, all without thinking about it. Other times we’re aware it is happening, though it still floats somewhere beneath the realm of reason and of willful actions.

There are some things that we do know about yawning:

  1. The average duration of a yawn is about 6 seconds.
  2. In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception – that’s BEFORE the baby is born!
  3. Yawns become contagious to people between the first and second years of life.
  4. A part of the brain that plays an important role in yawning is the hypothalamus. Research has shown that some neurotransmitters and neuropeptides increase yawning if injected into the hypothalamus of animals.

Most of us consider a yawn to be a precursor to sleep. We yawn because we are tired and need rest. However new research suggests that this is not the case. Some researchers now think the purpose of yawning is to cool the brain so it operates more efficiently and keeps you awake.

Brain Cooling Theory

Researchers found that people yawned more often when they pressed a warm or room temperature towel against their heads than when they pressed a cold towel against their heads. People who breathed through their noses (thought to reduce brain temperature) did not yawn at all.

This theory says that when we contagiously yawn we are participating in an ancient, hardwired ritual that evolved to help groups stay alert and detect danger. Scientists at the University of Albany in New York are behind the latest research:

“We think contagious yawning is triggered by empathic mechanisms which function to maintain group vigilance,” says Dr Gordon Gallup, a leading researcher at the university.

But there are other theories as well.

Herding Behavior

It’s been suggested contagious yawning could be a result of an unconscious herding behavior – a subtle way to communicate to those around us, similar to when flocks of birds take flight at the same time.

Communicating Sleeping Times

This theory suggests contagious yawning might have helped early humans communicate their alertness levels and co-ordinate sleeping times. If one person decided it was time to sleep they would tell the others by yawning and they would do it in return to show they agreed.

For more Theories on Yawning click here.

Previously only humans and chimps have been known to contagiously yawn, but in a recent experiment, dogs were shown to exhibit this tendency also.

The study of 29 dogs was conducted at the University of London in two stages. First, each dog watched a male researcher perform a large yawn, and then, in the control portion of the experiment, the dogs took turns observing the same researcher merely open his mouth.

  • 72%, or 21 of the 29 dogs, yawned after watching the researcher yawn.
  • No dogs yawned during the control portion of the experiment.

“Dogs are not only reading and responding but may be sharing feelings with humans,” said Atsushi Senju, a research fellow at the University of London’s Birkbeck College and one of the study authors.

Some Yawning Facts:

  • The average duration of a yawn is about 6 seconds.
  • Your heart rate can rise as much as 30 percent during a yawn.
  • 55 percent of people will yawn within five minutes of seeing someone else yawn.
  • Blind people yawn more after hearing an audio tape of people yawning.
  • Reading about yawning will make you yawn.
  • Olympic athletes often yawn before competition.

If you got to this point in this post – Congratulations!! – Its over. But be honest with yourselves: How many times did you yawn before getting here??

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