The Anatomy of a...

[Steven the Victor]

Yawn. what actually happens to the body when we do yawn. Is it really contagious? and why do we and animals yawn in the first place?
just curious is all.

[Ummon]

You perhaps mean physiology?

For brevity: http://en.wikipedia.org/wiki/Yawn

[Bokks]

It was once belived that you yawn when you needed a quick burst of oxygen. Now it's thought that you yawn to cool your brain down. I don't see why it can't be both, personally, since the human body usually finds more than one use for a particular action, so a yawn shouldn't be any different. Other than that, though, the contagious effect is the great suggestibility. I'm just sitting here thinking about a yawn and I'm ... there I go. Just yawned.
The only way to really prove that there isn't some kind of hormone or something released that makes us want to yawn, there'd have to be a study that has a person yawn behind someone who can neither see nor hear nor sense in any matter if and when the person yawns, and see what the effect is, then show a taperecorder or video that shows someone yawning and comparing the results. I suppose it is possible that a yawn is "contagious" by some kind of hormone, but I highlt doubt it. Since I'm just as apt to yawn in a movie as I am when I'm in close proximity to person actively yawning, I have faith that it's just the power of suggestion.

[QRS]

Other than that, though, the contagious effect is the great suggestibility. I'm just sitting here thinking about a yawn and I'm ... there I go. Just yawned.

Yawns aren't contagious in a physical way. It's all about the power of suggestion.

[KoS]

I believe I've read somewhere that it's the body's way of keeping you awake, kind of like a blast of cold water on your face.

[Broken Pope]

I always yawn uncontrollably when a jury is being sworn in. (I'm a trial attorney). I think it is either a nervous thing or an unconscious method of trying to forge a physical link between a group; to get people in-step with you psychologically.

As the wiki entry notes, You see prides of lions and ape colonies yawning together. Pretend to yawn next time you're on a train carriage - you'll see how receptive people are. Its shared body language.

[portugal11]

its ur soul trying to escape!!

[Gungalley]

Reminds me of an idiotic teacher of mine in primary school, who kept seeing my yawn in class and thoguht that I found her lessons boring. She complained to my parents and suggested that maybe I wasn't sleeping enough. Back then, I already knew that yawning has numerous causes, but nobody would believe me.

[Copperknickers II]

We are forbidden to yawn in my karate dojo. Apparently it upsets feng shuei, or something. We do yawn when we are tired though, there is no denying that.