yawning

[valentides]

when one person yawns why do other people follow

[commoner]

...well whatever the reason for the first person yawning, whether because of the stale air in the room (shortage of oxygen)...or sheer boredom maybe, I would expect everybody to be affected by this at roughly the same time....so they all start yawning together..........like if you threw a handful of pepper into the room they would all sneeze ;-)

[Quizmonster]

Click here for an interesting web-page on the topic.

[Nummy]

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

[andy-hughes]

Another theory is that this is a carry-over from primitive man.

When one member of the tribe saw a potential threat, he would 'yawn' which simultaneoulsy showed his fighting fangs, and silently warned the rest of the tribe, who each did the same until everyone saw.

The notion of inaccruate levels of carbon dioxide and / or oxygen is disproved by the fact that babies in the womb, who do not breathe air, still yawn.

[andy-hughes]

An interesting fact - psychopaths hardly ever yawn - but as with yawning in general, no-one really knows why.