why are yawns contagious?
353304
I don't know, how about you check the answers for the other 20 people who have asked this question already today?
307772
Just a guess...  When you yawn, you take in more air than normal.  This means you get more oxygen than normal.  In a situation where it might be important to get more oxygen than your normal breathing urge will provide, an animal that yawns will have an advantage over one that doesn't yawn.  Since there is no disadvantage to yawning and occassionally there is an advantage, a mutation that causes an animal to yawn in response to another yawn would be passed on.
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.
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".
164616
The exact reason is not known but there are a number of theories:\n\n1) Excess of carbon dioxide and lack of oxygen in the blood. The brain trieggers a yawn to expel carbon dioxide and inhale oxygen.\n2) Regulation of body temperature.\n3) An increase of certain neurotransmitters in the brain, specifically serotonin, dopamine, glutamic acid and nitric oxide.\n4) A yawn is similar to stretching in that it increases blood pressure and heart rate and also flexes many muscles and joints.
537048
Because according to psychology, they are sympathetic responses.  Its funny that in a test, people who didn't yawn after seeing others yawn were found to be anti-social.
526472
I learned somewhere that this is a survival thing--if you are yawning, there might be a lack of oxygen or you are about to need a lot of oxygen.  Your yawn alerts others so they supply themselves with oxygen as well.
204275
Yawning or "pandiculation," is still pretty much a mystery to psychologists. (I just asked a friend in the trade.) Aside from the obvious observations of how it's related to boredom and how it gets "contagious" after a certain period of development in people, there isn't that much information on it. Sorry. (Hey, this is info from an old friend, so you might want to check newer sources.)
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...
198710
When you yawn, you are attempting to take in as much air as possible, more oxygen gives more energy.  People in the immediate area are in competition for this air too and yawn as a response to retrieve air themselves
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.
963394
Heere are excerpts from the source:\nIn an effort to find the answer, the Finnish government recently funded a brain scanning study. The results turned up some hard-to-interpret, possible clues. It also confirmed the obvious: yawn contagion is largely unconscious. Wherever it might affect the brain, it bypasses the known brain circuitry for consciously analyzing and mimicking other people’s actions.\n\nThis circuitry is called the “mirror-neuron system,” because it contains a special type of brain cells, or neurons, that become active both when their owner does something, and when he or she senses someone else doing the same thing. \n\nMirror neurons typically become active when a person consciously imitates an action of someone else, a process associated with learning. But they seem to play no role in yawn contagiousness, the researchers in the new study found. The cells are have no extra activity during contagious yawning compared with during other non-contagious facial movements, they observed.\n\nBrain activity “associated with viewing another person yawn seems to circumvent the essential parts of the MNS [mirror neuron system], in line with the nature of contagious yawns as automatically released behavioural acts—rather than truly imitated motor patterns that would require detailed action understanding,” wrote the researchers, with the Helsinki University of Technology and the Research Centre Jülich, Germany. The findings are published in the February issue of the research journal Neuroimage.\n\nBut if seeing someone yawn doesn’t activate these centers, what does it do to the brain? The researchers found that it appears to strongly activate at least one brain area, called the superior temporal sulcus. But this activation was unrelated to any desire to yawn in response, so it may be irrelevant to the contagion question, the researchers added.\n\nPossibly more significant, they wrote, was the apparent deactivation of a second brain area, called the left periamygdalar region. The more strongly a participant reported wanting to yawn in response to another person’s yawn, the stronger was this deactivation. \n\n“This finding represents the first known neurophysiological signature of perceived yawn contagiousness,” the researchers wrote.\n\nExactly what the finding means is less clear, they acknowledged. The periamygdalar region is a zone that lies alongside the amygdala, an almond-shaped structure deep in the brain in the area of the side of the head. The periamygdalar region has been linked to the unconscious analysis of emotional expressions in faces. Why it would be deactivated in tandem with yawn contagion is unclear, the researchers said.\nFurther details can be had from the site.\nVR
1057558
It is possible that yawns are contagious because at one time in evolutionary history, the yawn served to coordinate the social behavior of a group of animals. When one member of the group yawned to signal an event, all the other members of the group also yawned. Yawns may still be contagious these days because of a leftover response (a "vestigial" response) that is not used anymore. None of this has been proven true and yawns are still one of the mysteries of the mind.\n\nAlso,\n\nThe reason yawns are contagious? Power of suggestion perhaps. If you're out late with your friends after school, you're probably tired. You're probably on the verge of a yawn, too, and seeing one person do it is enough to drive everyone to yawns.
435953
It's not that they are contagious.  Its just that people yawn because their brain isn't getting enough oxygen and when someone sees another person yawning they....yaaaaaaaawwwwnn.  And then another person sees THEM yawning and they think, "Hey, maybe MY brain needs more O2.  I think I'll just Yaaaaaaaawwwwn.  And then another person sees them yawning and they think, "Oh no, I don't have time to Yaaaaaaaaaawwwnnn."  And then another person sees them yawn and they sa...yaaaaaaaaaawwwwn.  I think this answer is making me sleepy.  Good night.
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
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!  :)
542822
yawning is usually a result of a slight lack of oxygen. therefore if one person yawns, the same conditions exist for others in the room.