why are yawns contagious?
337667
It's a psychological reaction.  You see someone yawm and then your brain wants you to yawn too.  For some reason I always want to yawn when I go down the back stairs at work.\n\nIt's the same way smoke makes some people want to cough.  Theatrical smoke is not suppose to make you cough, but every play I've seen with smoke people in the audience aways start coughing.\n\nDifferent conditions cause your body to react in different ways without you have to think at all about it.
40340
An indication of tiredness, stress, over-work or boredom. \nAn action indicating psychological decompression after a state of high alert. \nA means of expressing powerful emotions like anger, rejection or apathy. \n\nYou see someone yawning.  You hear someone yawning.  You read about yawning. You think about yawning. \nNow, you want to yawn. If this describes you, then you have just "caught" a yawn. Between 40 and 60% of the population is susceptible to contagious yawns, but the reason why yawns are catching is unknown. Steven Platek, Ph.D. suggests that being aware of one's own mental state ("self-recognition") and the ability to see things from another person's point of view ("mental state attribution") may make people susceptible to contagious yawns.
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!  :)
17567
Yawning is one of those bodily mysteries that scientists haven't completely figured out yet.  The best theory I could find was that you yawn because you're not getting enough oxygen to the brain (maybe there is a lack of oxygen in the space you're standing).  Whenever you're aware of someone yawning, it activates a reaction in your subconscious mind that acts as a threat response.  Basically, whenever you see someone yawn, it makes you body think there is a shortage of oxygen too, and you yawn in response.  No one knows if this is actually the case, but I think that it is a good theory.
811887
its so funny i read your question and it made me yawn and made me wonder so i looked it up for ya\n\n\n\nThe yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.[3] The proximate cause for contagious yawning may lie with mirror neurons, i.e. neurons in the frontal cortex of certain vertebrates, which upon being exposed to a stimulus from conspecific (same species) and occasionally interspecific organisms, activates the same regions in the brain[4]. Mirror neurons have been proposed as a driving force for Imitation which lies at the root of much human learning, e.g. language acquisition. Yawning may be an offshoot of the same imitative impulse. At a distal level (in terms of evolutionary advantage), yawning might be a herd instinct.[5] 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. This phenomenon has been observed among various primates. The threat gesture is a way of maintaining order in the primates' social structure. The contagion of yawning is interspecific, for example a human yawning in front of a pet dog can incite the dog to yawn as well. 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.
467214
Yawns are one of the brain's ways of getting oxygen and fighting fatigue. If someone yawns in response to your yawn it's because they are feeling the same fatigue you are.
213862
Why we yawn when we see others yawning has baffled scientists for ages and a number of suggestions have been put forward to explain this phenomenon. What we do know is that yawning is an involuntary action- our brain does it without us thinking about it, even very young babies yawn showing that it's a built in action (Chimps do it too by the way). Just thinking about yawning can trigger the bit of the brain that causes a yawn.  http://www.ratlab.co.uk/yawn.htm\n\nMore theories can be found at the links below:
273757
Seeing someone yawn, hearing them yawn, or even hearing the word "yawn" triggers a reaction in our brain. 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\nSo basically, it's an unconscious thing that the brain does, in most cases.
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.
414199
Yawning, like laughter, can be infectious. As to why this should be, there is little hard evidence, although yawning may be an arousal response that arose early in evolution and whose aim is to improve oxygenation of brain tissue and increase alertness, with a view to enhanced survival. In social groupings, the sight of one member yawning might act as a signal to cause other members to yawn - in some way the yawn is a warning that attention is slipping and the group may be at risk…\n\nResearch into the physiology and pathology of yawning appears to be quite limited. However, I have come across a couple of useful references. The first gives a general description of what happens when we yawn:\n\n"Yawning is a response to a wide variety of stimuli, including sleepiness and an awakening from sleep, hunger, boredom, nervousness, and intracranial disease. It is infectious, occurs more frequently in the newborn, and is likely to be more vigorous (especially the accompanying stretch) in early morning than late at night."\n\n"A yawn consists of an expansion of the chest, descent of the diaphragm and larynx, elevation of the ala nasi and soft palate, downward and backward movement of the tongue, abduction of the vocal cords, wide opening of the mouth, contraction of the tensor veli palatini muscle, closing of the eyes, lacrimation, pulling the head backwards, stretching of the upper arms sideward and the lower arms upward, and, less frequently, stretching of the legs. Vasoconstriction in the digits and cardiac acceleration have also been found to accompany the yawn. The whole act occupies 5 to 10 seconds, most of which time is spent in the inspiratory phase."\n\n"Although yawning certainly is an effective way of fully expanding the lungs and increasing the venous return to the heart, its psychic implications are also of great interest. The author finds that merely writing this is a potent stimulus towards yawning, and perhaps the reader is similarly stimulated." (Fenn and Rahn 1964)\n\nA good review of yawning is provided by Askenasy (1989), and the points that follow are derived from this source. Apparently, yawning movements have been observed in fetuses as early as the 15th week after conception, and continue to occur sporadically throughout the remainder of pregnancy. The newborn baby yawns a few minutes after birth. The frequency of yawning gradually diminishes as the baby matures\n\n\nSeveral causes of yawning are discussed in the review:\n\n psychological - this includes boredom, drowsiness, fatigue, separation, imitation, and autosuggestion \n\n hormonal - ACTH and MSH \n\n neurological - various brain pathologies including coma, encephalitis, hypoxia, and neoplasms \n\n psychiatric - for example schizophrenia, psychosis, depression and withdrawal \n\n general pathologies - ear disorders, gastric and biliary disorders, and motion sickness \n\n drug overdose - for example naloxone, valproate, imipramine, clomipramine, seratonin, and pentobarbital \n\n drug withdrawal - from heroin, morphine, lefetamine, methadone, and pentazocin.
292528
Yawns usually occur because you have some lack of oxygen, usually when you are growing sleeping and not breathing properly. When a person yawms next to you, you usually stop breathing yourself, thus triggering a "contagious yawn." Need to prove this false? Next time you see someone yawn, be concious of it and make yourself take a deep breath. You wont get that contagious yawn!
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".
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.
635799
1. because your body needs oxygen\n2. becaus you are bored and it is a way for your body to tell you to do something else\n3. becaus other people yawn. it is a social behavior that makes a group "stay together" \n\nhow? not sure, but I think your brain open your mouth and make your lungs draw in lots of air without letting you know first.
922965
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. Studies 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\nalso when we someone else yawn if someone else yawns, we are naturally competitive so if someone else is getting more oxygen, our body wants more.
325601
Professor Andrews told Scientific American yawns may be contagious because we human animals are trying to communicate changing environmental conditions to others, possibly as a way to synchronize behavior. Obviously, this would be one of those caveman-type mechanisms that is no longer needed that our bodies remember and still do.\n\nWhen we yawn, we draw in more oxygen and remove a build-up of carbon dioxide. Larger groups produce more carbon dioxide. So one theory holds that we yawn when we're in large groups of people to purge the carbon dioxide--and in so doing, we set off a chain reaction. But Robert Provine, a psychologist at the University of Maryland, Baltimore County, tested the theory and says it's bunk. 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, notes the How Stuff Works Web site.\n\nWhatever the reason for yawns being contagious, How Stuff Works reports that 55 percent of people will yawn within five minutes of seeing someone else yawn. In addition, blind people will yawn after hearing others yawning. And we're sure that reading and writing about yawns is enough to induce one!