Smile

A smile is a face made by flexing the muscles near both ends of the mouth.Freitas-Magalhães A. & Castro E. 2009. The neuropsychophysiological construction of the human smile. In A. Freitas-Magalhães (ed) Emotional expression: the brain and the face. 1-18 Porto: University Fernando Pessoa Press.  The smile can also be made through the eyes (See 'Duchenne smile' below). Smiles usually express happiness. A smile can be natural or fake. However, smiling can be different with animals. When smiling, the teeth shows, but sometimes animals do this when they are threatening. When chimpanzees show their teeth, it can also be a sign of fear.

 Dimples 

Dimples are genetically inherited. They are caused by the flesh underneath the skin, that forms on some people's cheeks, especially when they smile. Some people may only have one dimple on only one side of the face.

 Duchenne smile 

Although there are many different types of smiles, researchers are interested in the duchenne smile because it is done with the eyes. The Duchenne smile was named after the French physician Guillaume Duchenne. Duchenne identified two types of smiles. A Duchenne smile is when the cheek raises and forms a wrinkle around the eyes.Duchenne, Guillaume 1990. The mechanism of human facial expression. New York: Cambridge University Press. (Original published 1862) Many researchers think that Duchenne smiles are usually hard to make when you are pretending to smile.Ekman P., Friesen W.V. and O'Sullivan M. 1988. Smiles when lying. Journal of Personality and Social Psychology. 54 414–420

Internet

On the Internet, smiles can normally be typed up. This is normally called a smiley, smiley face, or happy face. Smileys show emotion when people are not able to see it in real life. Smileys typed on the computer are called emoticons. Smileys can change depending on where the person typing the smiley is.

Western Style: :-), :-(, ;-), :-O, :-D, (;D)

Eastern Style: d(^.^)b, \(^o^)/, >.<, ^_^, *<):)

Related pages
Laughter
Smiley
Social psychology

References

More reading
Conniff, R. (2007). What's behind a smile? Smithsonian Magazine, 38,46-53.
Ottenheimer, H.J. (2006). The anthropology of language: An introduction to linguistic anthropology. Belmont, CA: Thomson Wadsworh.
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. 
Russell and Fernandez-Dols eds. 1997. The psychology of facial expression. Cambridge. .
 Messinger D. & Fogel A. 2007.  The interactive development of social smiling. In  Robert Kail (ed) Advances in child development and behavior, 35, 327-366. Oxford: Elsevier. Retrieved 25 June 2010 from 

 Other websites 

 BBC News: Scanner shows unborn babies smile

Category:Non-verbal communication
Category:Social influence