why when you see or hear someone yawn, do you automatically yawn too???
414151
What's behind this mysterious epidemic of yawning? First, let's look at what a yawn is. Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply. We know it's involuntary because we do it even before we are born. Research shows that 11-week-old fetuses yawn. \n\nThere are many parts of the body that are in action when you yawn. First, your mouth opens and jaw drops, allowing as much air to be taken in as possible. When you inhale, the air taken in is filling your lungs. Your abdominal muscles flex and your diaphragm is pushed down. The air you breath in expands the lungs to capacity and then some of the air is blown back out. \n\nWhile the dictionary tells us that yawning is caused by being fatigued, drowsy or bored, scientists are discovering that there is more to yawning than what most people think. Not much is known about why we yawn or if it serves any useful function, and very little research has been done on the subject. However, there are several theories about why we yawn. Here are the three most common theories: \n\n\nThe Physiological Theory -- Our bodies induce yawning to drawn in more oxygen or remove a build-up of carbon dioxide. This theory helps explain why we yawn in groups. Larger groups produce more carbon dioxide, which means our bodies would act to draw in more oxygen and get rid of the excess carbon dioxide. However, if our bodies make us yawn to drawn in needed oxygen, wouldn't we yawn during exercise? Robert Provine, a psychologist at the University of Maryland, Baltimore County, and a leading expert on yawning, has tested this theory. Giving people additional oxygen didn't decrease yawning and decreasing the amount of carbon dioxide in a subject's environment also didn't prevent yawning. \nThe Evolution Theory -- Some think that yawning is something that began with our ancestors, who used yawning to show their teeth and intimidate others. An offshoot of this theory is the idea that yawning developed from early man as a signal for us to change activities. \nThe Boredom Theory -- In the dictionary, yawning is said to be caused by boredom, fatigue or drowsiness. Although we do tend to yawn when bored or tired, this theory doesn't explain why Olympic athletes yawn right before they compete in their event. It's doubtful that they are bored with the world watching them. \nThe simple truth is that even though humans have been yawning for possibly as long as they have existed, we have no clue as to why we do it. Maybe it serves some healthful purpose. It does cause us to draw in more air and our hearts to race faster than normal, but so does exercise. There's still much we don't understand about our own brains, so maybe yawning is triggered by some area of the brain we have yet to discover. We do know that yawning is not limited to man. Cats, dogs, even fish yawn, which leads us back to the idea that yawning is some form of communication. \n\nHave we provoked a yawn out of you yet? If we have, hopefully it's not out of boredom, but by the power of suggestion.
317540
A Yawn is the brain's natural way of rapidly increasing the amount of oxygen taken into the lungs for use by the body during times of fatigue. It is triggered by very delicate mental cues and accordingly, can be triggered by seeing someone else yawn or even thinking about yawning long enough.
260771
we yawn when we get bored and it is very embarrsing esp. in public places,with me once they start they go on and on. maybe you idnt check yourself form childhood and now its a habit. force yourself to stop opening the mouth you will gradually overcome it.
196592
It is the brain requiring more oxygen. Which is why when someone else yawns you do to, it is your brain making sure that it has enough in case the other person takes it all. Not very likely to happen unless in a confined space, but the brain is always on survival mode.
300748
WHen you see another person yawning, the message goes across your brain that may be you too needs more oxygen and in attempt to get more air in, you open your mouth wide open, your lungs expand and you yawn. That's why it's called reflex yawning
1177906
Yawning is your body's attempt to get more oxygen.  When you are tired, your breathing tends to get more shallow, and your body tries to compensate by making you yawn - bringing in more oxygen.\n\nHere's some more information on yawning, and why it's "contagious".
830
monkey-see monkey-do. Dr. Steven M. Platek has said that we yawn b/c we are unconciously imitating other humans. (probably some kind of evolution thing) I guess there are many other species that yawn...fish, cats...(i would totally pay to see a fish yawn!).\nBy the way although it used to be believed that it was to get more oxygen, this, however, is not true.
410453
we yawn b/c our body is craving more oxygen.. this is fact
202412
THE TRUTH IS that we don’t completely understand why people, or animals for that matter, yawn. It’s widely assumed that yawning occurs because we are tired or bored or because we see someone else doing it, but there isn’t any hard evidence to support these beliefs.\n\nThe most plausible explanation, and the one that is taught in medical school, is that we yawn because oxygen levels in our lungs are low. \n\nStudies have shown that during normal, at-rest breathing, we don’t use anywhere near our lung capacity; for the most part, we just use the air sacs at the bottom of the lungs. If the air sacs, called alveoli, don’t get fresh air, they partially collapse and the lungs stiffen a bit. As a result, it’s believed, our brain prompts the body to either sigh or take a yawn to get more air into the lungs.\n\nBut certain aspects of yawning remain even more mysterious. Fetuses, for instances, have been observed yawning in the womb, yet it’s known that they don’t take oxygen in through their lungs. And yawning seems to be a symptom of multiple sclerosis and other medical conditions, for reasons unclear.\n\nAnother puzzling phenomenon is that some male animals, men included, yawn in association with penile erection (although it’s presumptuous to assume they’re bored with their sex lives).
304410
I can't remember where I heard this but someone told me it's an empathetic response. Like the more in tune you are to others feelings, the more likely you are to yawn when you see someone else do it.
142620
No..A yawn is something your body does when it needs a little more oxygen. Like if you were in a small area your body will yawn to get as much oxygen it can and remove the carbon dioxide .. all you have to do is take a deep breath and go about your business..
257093
Not sure...but you don't have to see someone yawn to make you yawn. Just hearing a yawn is enough, sometimes.
422922
It is also believed to be linked to social bonding.\n\nExperiments with chimps have shown that they also yawn when another chimp yawns.  Also videos (night video) in caves, where there is no light, where a certain species of monkey sleep - shows that they all yawn audibly before going to sleep.  Kind of a way of letting everyone know that they're there, even though they can't see each other.\n\nThis has probably carried through to humans.\n\nHave a look at http://www.theanswerbank.co.uk/Science/Question117042.html\n\nor\nhttp://webperso.easyconnect.fr/baillement/contagion-platek.html
441827
See the article in the site below.  It tells you why we yawn and gives evidence to support the theory that yawning is "contagious" because "as social creatures we are highly inclined to copy one another."\n\nThe article starts by saying that a good trick to see if anyone is checking you out is to yawn and see if anyone else yawns back!  \n\nHope this helps...
276956
When working out the blood flow is increased to the working muscles. As a result there is less blood and oxygen flowing to the brain triggering the yawn. This is your body's way of increasing the oxygen level in the brain to compensate.\nAs your body accomodates the increased physical demand, the yawning should become less.
433222
because they make one tired so then they person that isn't tires suddenly becomes tires and yawns. but yawns shouldn't make one another person yawn because the person is just releasing co2 from their bodies.
1159613
Ahhh... the age old question. lol\n\nThere are a number of theories. One is that when someone yawns, they take oxygen out of the air, and we need the oxygen so we yawn to get the oxygen we need. I'm not sure about that one. I think its just a joke.\n\nA more likely theory is that it relates back to the herd instinct. You know, monkey see, monkey do.