Why are yawns contageious?
461426
Seeing running water makes you want to go, it's the same with yawning, it's an involuntary reaction to seeing someone else do it before you. \nAn Auto suggestive sequence and it can spread.
470027
Not sure... Never did have yanws...\n\nA Yawn:The yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.[2] The reasons for this are unclear; however, recent research suggests that yawning might be a herd instinct.[3] Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, canine teeth, thus proclaiming, "don't attack while I am sleeping..." The contagion of yawning is interspecific (i.e., try yawning in front of your dog). Ironically, yawning in public is generally regarded as impolite in the West, but came into fashion in polite French society for a brief period in the late 18th century. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word "yawn".
609665
Because they trigger the receptors in the brain to relax.  Yawning signals relaxation to other humans, thus causing themselves to inadvertantly yawn.  It's like human relation reflex.
326667
Here are some very cool links about yawning in general and why it is contagious:\n\nhttp://www.howstuffworks.com/question572.htm\n\nhttp://staff.washington.edu/~chudler/yawning.html\n\nhttp://www.world-science.net/exclusives/050309_yawnfrm.htm\n\nBy the way, excellent question.  Hope this helps.\n\nGod Bless!  :)
217186
In humans, and probably in all those organisms that yawn, yawning is caused by a lack of oxygen. When we are tired, we breathe less often as well as less deeply, so our bodies have evolved a way to fix that problem: forced deep breathe.
375489
Virtually any stimulus associated with yawns -- including viewing, reading about, and even thinking about, yawning -- evokes yawns. (Are you yawning yet?) Yawning spreads in a chain reaction through a group, a compelling example of human herd behavior and a reminder that we are not always in conscious control of our actions. The urge to replicate an observed yawn is clearly an automatic response triggered by our brains.\n\nStudies partially explain the reason for yawning. Although we yawn more when sleepy or bored, it is unclear whether yawning increases alertness. And scientific evidence refutes one of the most popular myths of yawning? that it happens in response to low oxygen or high carbon dioxide levels in the blood or brain. Test subjects do not yawn more when breathing air with enhanced levels of carbon dioxide nor do they yawn less when breathing pure oxygen. One fact explains a lot of apparently inconsistent data. People yawn most during behavioral transitions, such as just after waking and shortly before bedtime. Yawning may help facilitate those changes. Contagious yawning may synchronize a group's behavior so that, for instance, a whole family goes to sleep together.
347438
It's a subconscious thing.  When a person is yawning, their body is sensing that it is not getting enough oxygen.  Something in our subconscious sets off, and causes us to yawn when we see someone else do it.
936410
because your brain thinks the other person is stealing all the air so makes you yawn to try and get some yourself, therefore staying alive.\n\nThere's also that it's merely the power of suggestion.\n\nFound this also http://in.answers.yahoo.com/question/index?qid=20061031003314AAoMMUh
337700
From a lack of oxygen. Yawning is when your blood circulation slows down i.e at high altitude average people yawns at least 7 times per minutes.\n\nAlso a sign that adrenaline is slowing down and if inactive, the body will shut down.  Involuntary but necessary, seeing people doing so reminds us that the body needs it...
289289
Between 40 and 60% of the population is susceptible to contagious yawns, but the reason why yawns are catching is unknown.\n\nI yawned once when typing up this answer.
967357
The answer is, no one really knows why yawning is "contagious". Or why we yawn at all. One popular explanation is that yawning allows you to get rid of too much carbon dioxide in your system and increase your oxygen supply. This was disproved by Dr. Robert Provine and his research team in 1987.\n\nNow scientists are wondering if yawning is from our deep past -- part of our evolutionary history. Did a yawn signal to the group that it was time for everyone to retire to the trees and snooze? Did a yawn signal that we were all feeling cozy and warm about each other? Did a yawn signal something more like, "Gee, I know how you're feeling, I feel that way too."\n\nBetween 40 and 60 percent of the population seems to find yawning contagious. Researchers at the State University of New York conducted a series of yawning experiments. They determined that being self-aware (the ability to recognize oneself) and having the ability to see things from someone else's viewpoint means a person is more likely to find yawning contagious.\n\nNow you're thinking, what humans are not self-aware? Schizophrenics sometimes have trouble with self-recognition so they will not find yawning contagious. Babies won't yawn contagiously until they're more than a year old.\n\nSome birds and reptiles yawn. Most mammals yawn. My dog yawns, but that doesn't make me yawn -- I obviously cannot put myself in her paw prints. (But who can empathize with a creature that sleeps all day, then when she does bother to get up and join you on a walk, suddenly bolts after a squirrel and nearly tears your arm out of your socket? I have no idea what's going on in that dog's mind.)\n\nChimpanzees yawn too, and in fact, if they watch other chimps yawn, they're more likely to yawn too.\n\nSo, I guess the real answer is: who knows?
361765
Not really sure---but just seeing the word yawn made me yawn--Thanks alot---yawns again---wonders about yawns--yawns again-- http://en.wikipedia.org/wiki/Yawn Why are yawns contagious? Getting kind of tired-- http://www.straightdope.com/classics/a2_309.html-- Why do we yawn? http://faculty.washington.edu/chudler/yawning.html A yawn reasearcher? http://psychology.drexel.edu/ECNL/  Huh? Sorry must be groggy--Pictures of animals yawning --Oh No-- yawning out of control-- http://www.animalyawns.com/ all this reading about yawning ---YAWNS deeply--- I'm getting so sleepy ---  It's hard to keep my eyes open--z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z
230012
Well, I don't know why yawns are contagious because scientists really don't know what cause yawn's in the first place. However, on a lesser level, I believe yawns are contagious because when you see someone yawn, you tend to think of how tired you are. Therefore, you yawn too. And plus it is pretty amusing when you have a yawn fest with someone and just cannot stop yawning back and forth.\nHope this helps!
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.
1051186
When a person yawns it is usually due to the lack of oxygen to the brain. When we see a person yawning our brain interprets  it as low level of oxygen in the air.As a result we yawn.
329034
We yawn because of a lack of Oxygen. Think about it: when you yawn more air comes in and sometimes after a yawn you feel rejuvenated for a little while. But this is contagious because if you yawn you are probably in an Oxygen-deprived environment and everyone around you is going through the same lack of Oxygen. And yawning is related to sleep because when you're asleep you're barely doing more than breathing, beating your heart and dreaming which doesn't take up much oxygen but you still get the same amount of oxygen as you would awake in the same room so there's more oxygen to relax your brain and mind and everything else that might be tired.
694355
more recent hypothesis is that yawning is used for regulation of body temperature. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the brain that affect emotions, mood, appetite and other phenomena. These chemicals include serotonin, dopamine, glutamic acid and nitric oxide. As more of these compounds are activated in the brain, the frequency of yawning increases