Why is Yawning so Contagious?

Ever been in a room full of people or on public transit, someone yawns and it sets off a chain reaction? Why is that?

You know that when we're bored, we yawn. Scientists have confirmed this observation. A yawn signifies a lack of oxygen to our brains. When we are bored or tired, we breathe more slowly. If our breathing slows down, less oxygen makes it to our lungs. As carbon dioxide builds up in our blood, our brain gets a message and tells your lungs to "take a deep breath," and we yawn. Okay. What else? Well, of course we all yawn when we're sleepy too, but that's a given.

Did you know that everyone yawns - babies, kids, teenagers and adults. Animals even yawn. There's the lack of O2 theory, but the exact reason why we yawn is a bit of a conundrum. There's not much research about yawning because for most of us yawning doesn't present a problem (unless we're in a business meeting, in class, on a date or with our partner! Ha!). Here are some interesting things that we've been able to figure out about yawning:

• The average duration of a yawn is about 6 seconds.
• In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception - that's BEFORE the baby is born!
• Yawns become contagious to people between the first and second years of life.
• Your heart rate can rise as much as 30 percent during a yawn.
• 55% 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.

That's all good and well, but WHY is yawning contagious? Well, we named the physiological need for oxygen, and boredom, but some think that yawning is also evolutionary. It's something that began with our ancestors, who used yawning to show their teeth and intimidate others.

A side theory is that yawning developed from early man as a signal for us to change our activities. Also, in animals, the yawn served to coordinate social activities - when one member of the group yawned to signal an event, all the other members of the group also yawned. Maybe we're all signaling to one another that we're bored and we need to find something better and more interesting to do?

Though the 'yawn' has been around for as long as humans have existed, we have no idea why we do it. The safest conclusion is that it's totally unconscious. There's still a lot we don't understand about how our brain works, so maybe yawning is caused by some undiscovered area of our brain. We do know, however, that yawning is not limited to man. Cats, dogs, even fish yawn, leading again to the notion that yawning is some form of nonverbal communication.

Just for fun, next time you're in a meeting, class or in transit and bored beyond belief, yawn, and see how many other people 'communicate' that they would rather be elsewhere by yawning right along with you!