The scientists that studied this have not confirmed this, but it is more likely for a person to start a chain reaction of yawns. Some say it has to do with too much carbon dioxide build up in the body and you nedd to get it out by yawning (breathing in= more oxygen). Others say it has to do with a natural reaction that cavemen used to use when communication. I don't know what to believe but i believe it has to do with the pyschological aspect of it. Maybe somewhere deep in your brain, whne another person yawns, you have to do it. I believe it relates way back to the cavemen, which many scientists speculate.

I don't know about this chain reaction stuff but whenever a girl yawns around me I put my cock inside. I thought every one did that.

k i hav this theory that the reason that wen sum1 yawns and then evry1 else yawns... it is becoz it is a reflex from the caveman times. my theory is that wen 1 of the cavemen yawned... the others thought thta he was takin all the oxygen... so they all yawn too to get ther share. its probz pretty stoopid but its my theory and rle if u think about it it dus kinda explain it

It is a proven fact that yawning is contagious

People yawn when they are tired- I think that is has to do with oxygen intake- I believe the contagious reflex was an adaptation that early humans used within their tribes to announce that it was time to rest or sleep.

just readiny thats make me yawn. oh man just the announcement of ayawn maktes me do it. hahahha its superr contagious

xprincessaimix is cute but pretty fucking stoopid.

Hey! im not stoopid! lol