Why are yawns contaigous?Follow

On an unrelated note to your actual post, yawns are contaigous because when a person yawns close to you it creates a large amount of carbon dioxide in the immediate area. Because yawns are the bodies reflexive way to rapidly intake oxygen for the brain, the sudden lack of oxygen in the area of the person who yawned creates a reflexive reaction by your body to increase oxygen, or yawn.

Edit: Because corbon dioxide is toxic to ducks and I won't condone it's presence in my post.

Edited, Tue Dec 13 20:40:49 2005 by allenjj

If that is why people yawn, why do people "catch" a yawn over the telephone or when someone does it on TV?

Because it's a reflexive reaction rather than a conscious decision, the body reacts to the act of someone yawning, be it seen, heard, or actually experienced, with a yawn of it's own.

Edit to add: The body interprets a yawn seen on television or heard on the phone as a need to increase oxygen due to the response created by an actual yawn.

Edited, Tue Dec 13 21:22:25 2005 by allenjj

I've yawned every time I've opened this thread, take that as you will.