Why is a yawn so infectious?

I think a yawn is a very primitive signal to say "I am not feeling aggressive." Other animals do it as well - cats are well known for it and dogs, too.

http://www.world-science.net/exclusives/050309_yaw...

http://www.islandnet.com/~yesmag/Questions/yawn.ht...

for two very interesting takes on the subject.

There are other things that we copy about other people too. If you are having a conversation with someone, try casually crossing one leg over the other. See how long it takes for them to mirror your action.

It's a throwback to our days as tribal primeval apes. When one ape smelled or sensed danger, he would yawn, which served as a silent warning to the rest of the tribe, as well as showing off his fighting fangs to the interloper. This would trigger a duplicate response from any other apes who saw it, so that the message would spread quickly and silently round the tribe. As with a number of other inbuilt safety measures, this is one that has not yet evolved out of mankind's physiology, even though the need for it has long since ceased. That's why when we see someone yawn, we get the subconcious urge to do the same. It is deemed sufficiently important as a defence mechanism that foetuses in the womb have the facilty inbuilt in the very earliest weeks of development.

It depends on what caused the first yawn, if it's low oxygen in the air then the answers obvious. If the first to yawn is tired then I don't know. I usually yawn more when the weather is hot and humid I also feel less energetic than in winter, because the oxygen tends to be less then too.

This goes back to prehistoric times, right at the time when humans were evolving...they used to hunt in groups and just before the attack ideally they would have like to have their bodies synchronised in terms of the need for sleep, need to urinate and even the need to defecate so that in the middle of a crucial moment some members of their group should not say to the leader 'Sir, I want a break to go to the loo!' so it was our evolutionary trait that yawns are infectious. (In an open place even urination is infectious!). Eventhough we don't have a need to hunt together we still live and work together so we try to synchronise our sleep times.

You see it the animal kingdom. The leader of the pack yawns and signals to the rest of the group that they too can relax. I don't know what the benefit of that is to the leader or the group.

The reason its infectious is because you pcik up the message at a subconscious level (i.e. beneath the level of language) and you respond accordingly. Its something you first pick up at a very early age.

Okay, so yes it's human nature - when we see something - we often replicate; example, a smoker may want to light up more than often - when they see someone else smoking. When you see someone yawning, the part of your brain which is not controlled (by you); will take control and act as a mirror image, it is even perhaps a miracle if you do not replicate a yawn.......

It's true, even in implication. I answered a question on yawning 2 mins ago. Shortly after that I yawned!

I've noticed this too. I tried testing the principal to see if it was replicated in any other actions. I was in a lift full of women and lifted my top to reveal my breasts and tried licking my left nipple. Unfortunately none of the other occupants felt the infectious need to do likewise. I guess it's just yawning then!

I disagree... oh, my excuse me... that a a wwoooo yawn is infect oooo my my I must be sleepy, I think I am going to take a nap a ooooo goodness. and come back and answer this later.

i dont know the reason, but this subject came up in my psychology class and my psych teacher told me that if u wana know whether someone likes u, keep yawning and eventually, they will yawn too....this is because they keep watching u and then yawn themselves! lol, i tried it and it worked!