Smile

For other uses, see Smile (disambiguation).

This article is about the facial expression. For the typographical symbol, see smiley.

A Nepali woman smiles.

The presence of cheek dimples is controlled by a single gene.

In physiology, a smile is a facial expression formed by flexing those muscles most notably near both ends of the mouth. The smile can also be found around the eyes (See 'Duchenne smile' below). Among humans, it is customarily an expression denoting pleasure, happiness, or amusement, but can also be an involuntary expression of anxiety, in which case it can be known as a grimace. There is much evidence that smiling is a normal reaction to certain stimuli as it occurs regardless of culture. Happiness is most often the motivating cause of a smile. Among animals, the exposure of teeth, which may bear a resemblance to a smile, is often used as a threat or warning display - known as a snarl - or a sign of submission. In chimpanzees, it can also be a sign of fear. The study of smiles is a part of gelotology, psychology, and linguistics, comprising various theories of affect, humor, and laughter.

• Very Happy
  Very Happy

==Historical background==

Many biologists think the smile originated as a sign of fear. Primalogist Signe Preuschoft traces the smile back over 30 million years of evolution to a "fear grin" stemming from monkeys and apes who often used barely clenched teeth to portray to predators that they were harmless. Biologists believe the smile has evolved differently among species and especially among humans.

Biology is not the only academic discipline that interprets the smile. Those who study kinesics view the smile as an affect display. It can communicate feelings such as: love, happiness, pride, contempt, and embarrassment. More info: The Psychology of Human Smile, The Smile

Duchenne smile

A laughing smile with teeth showing and mouth open.

A Duchenne smile contracts the zygomatic muscles of the cheek and eye, forming crow's feet. The crow's feet indicate that the smile is genuine and that the smiler is truly happy. It was discovered by and is named after Guillaume Duchenne.

Gallery

• 
  The painting Mona Lisa by Leonardo da Vinci.
• 
  Girl with closed mouth smile.
• 
  Girl with open mouth smile.
• 
  Politicians and leaders are often shown smiling as this is considered a sign of hospitality and confidence. With President Gerald Ford U.S. Presidents began smiling in their official portrait photos.
• 
  Artwork on this ball is a common abstract representation of a smiling face.
• 
  The Philosopher Democritus, by Agostino Carracci.

See also

• Laughter
• Emotion
• Emoticon
• Facial Action Coding System
• Frown
• Facial expression
• Smiley
• Social Psychology

Further reading

• Conniff, R. (2007). What's behind a smile? Smithsonian Magazine, 38,46-53.
• Miller, Professor George A., et. al. Overview for "smile." Retrieved 12 December 2003 from this page.
• Ottenheimer, H.J. (2006). The anthropology of language: An introduction to linguistic anthropology. Belmont, CA: Thomson Wadsworh.

Duchenne smile

• Freitas-Magalhães, A. (2006). The Psychology of human smile. Oporto: University Fernando Pessoa Press.
• Ekman, P., Davidson, R.J., & Friesen, W.V. (1990). The Duchenne smile: Emotional expression and brain psysiology II. Journal of Personality and Social Psychology, 58, 342-353. Cited in: Russell and Fernandez-Dols, eds. (1997).
• Russell and Fernandez-Dols, eds. (1997). The Psychology of Facial Expression. Cambridge. ISBN 0521587964.

External links

• Facial Emotion Expression Lab
• See examples of genuine, false, and contempt smiles
• Spot The Fake Smile on BBC Science & Nature
• Expressions of Positive Emotion in Women's College Yearbook Pictures and Their Relationship to Personality and Life Outcomes Across Adulthood.
• BBC News: Scanner shows unborn babies smile