Laughter

Laughter is the biological reaction of humans to moments or occasions of humor: an outward expression of amusement. Laughter is subcategorised into various groupings depending upon the extent and pitch of the laughter: giggles, clicks (which can be almost silent), chortles, chuckles, hoots, cackles, sniggers and guffaws are all types of laughter. Smilingmay be considered a mild silent form of laughter. Some studies indicate that laughter differs depending upon the gender of the laughing person: women tend to laugh in a more "sing-song" way, while men more often grunt or snort. Babies start to laugh at about 4 months of age. PhilosopherJohn Morrealltheorises that human laughter may have its biological origins as a kind of shared expression of relief at the passing of danger. The relaxation we feel after laughing may help inhibit the fight-or-flight response, making laughter a behavioral sign of trust in one's companions.

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On the other hand, laughing at somebody is considered to be ridiculing the individual. However, many consider this form of laughter to be the mind's way of "vomiting" negative, unwanted things and thoughts not of the self. For example, a young boy may see another boy fall down, he laughs because he knows that he does not want to fall down himself, therefore by "laughing" he is pushing the negative thought of falling down out of his mind.

Laughter is a part of human behaviorregulated by the brain. It helps humans clarify their intentions in social interaction and provides an emotional context to our conversations. Laughter is used as a signal for being part of a group — it signals acceptance and positive interactions. Laughter is sometimes contagious and the laughter of one person can itself provoke laughter from others. This may account in part for the popularity of laugh tracksin situation comedytelevision shows. A particularly dramatic demonstration of contagious laughter was the Tanganyikan laughter epidemic, which demonstrated that laughter can also be difficult to control and can occur, unpleasantly, when people are severely stressed.

However, laughter in certain contexts can feel threatening as in drama. For instance, the BatmansupervillainThe Jokeris an insane clownlike criminal who finds violent crime hilarious and often laughs hysterically for the slightest reason, especially when commiting murder. Furthermore, one of his favourite methods is a deadly poison that causes the victims to laugh uncontrollably before death.

Certain medical theories attribute improved health and well-being to laughter as it triggers the release of endorphins. A study demonstrated neuroendocrineand stress-related hormonesdecreased during episodes of laughter, which provides support for the claim that humor can relieve stress.

Research has shown that parts of the limbic systemare involved in laughter. The limbic system is a primitive part of the brainthat is involved in emotions and helps us with basic functions necessary for survival. Two structures in the limbic system are involved in producing laughter: the amygdalaand the hippocampus.

Researchers frequently learn how the brain functions by studying what happens when something goes wrong. People with certain types of brain damageproduce abnormal laughter. This is found most often in people with pseudobulbar palsy, gelastic epilepsyand, to a lesser degree, with multiple sclerosis, ALS, and some brain tumors. Inappropriate laughter is considered symptomatic of psychological disorders including dementiaand hysteria.

In most people, laughter can be induced by tickling, a phenomenon in itself. Laughing gasis sometimes used as a painkiller. Other drugs, such as cannabis, can also induce episodes of strong laughter. At rare times, pain can sometimes be used to create laughter, though not necessarily with sadistic or masochistic reasoning.

The December 7, 1984Journal of the American Medical Associationdescribes the neurological causes of laughter as follows:

"Although there is no known "laugh center" in the brain, its neural mechanism has been the subject of much, albeit inconclusive, speculation. It is evident that its expression depends on neural pathsarising in close association with the telencephalicand diencephaliccenters concerned with respiration. Wilson considered the mechanism to be in the region of the mesial thalamus, hypothalamus, and subthalamus. Kelly and co-workers, in turn, postulated that the tegmentumnear the periaqueductal graycontains the integrating mechanism for emotional expression. Thus, supranuclear pathways, including those from the limbic systemthat Papez hypothesized to mediate emotional expressions such as laughter, probably come into synapticrelation in the reticular core of the brain stem. So while purely emotional responses such as laughter are mediated by subcortical structures, especially the hypothalamus, and are stereotyped, the cerebral cortexcan modulate or suppress them."

Laughter might not be confined to humans. Chimpanzeesshow laughter-like behavior in response to physical contact, such as wrestling, chasing, or tickling, and ratpups emit short, high frequency, ultrasonicvocalizations during rough and tumble play, and when tickled. Rat pups "laugh" far more than older rats. Chimpanzee laughter is not readily recognizable to humans as such, because it is generated by alternating inhalations and exhalations that sound more like breathing and panting. The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. However, some behavioral psychologists argue that self-awareness of one's situation, or the ability to identify with somebody else's predicament, are prerequisites for laughter, so animals are not really laughing in the same way that we do.

See also

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• evil laugh
• LOL (Internet slang)
• Tickling
• Comedy
• Humour
• Joke
• Satire
• Corpsing

References

• Goel, V. & Dolan, R. J. The functional anatomy of humor: segregating cognitive and affective components. Nature Neuroscience 3, 237 - 238 (2001).
• Bachorowski, J.-A., Smoski, M.J., & Owren, M.J. The acoustic features of human laughter. Journal of the Acoustical Society of America, 110 (1581) 2001
• Fried, I., Wilson, C.L., MacDonald, K.A., and Behnke EJ. Electric current stimulates laughter. Nature, 391:650, 1998 (see patient AK)
• Provine, R. R., Laughter. American Scientist, V84, 38:45, 1996.

External links

• The Origins of Laughter
• Funny Jokes
• Humour therapy for cancer patientsca:Riure

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It uses material from the http://en.wikipedia.org/wiki/Laughter Wikipedia article Laughter.