SMILE

                                             

A smile is a facial expression formed primarily by flexing the muscles at the sides of the mouth.  Some smiles include a contraction of the muscles at the corner of the eyes, an action known as a "Duchenne smile". Smiles performed without the eye contraction can be perceived as "fake".

Among humans, smiling is an expression denoting pleasure, sociability, happiness, or amusement. It is distinct from a similar but usually involuntary expression of anxiety known as a grimace. Although cross-cultural studies have shown that smiling is a means of communication throughout the world, there are large differences between different cultures, with some using smiles to convey confusion or embarrassment.

A smile seems to have a favorable influence upon others and makes one likable and more approachable. In the social context, smiling and laughter have different functions in the order of sequence in social situations:

Smiling is not a pre-laughing device and is a common pattern for paving the way to laughter;

Smiling can be used as a response to laughter in the previous turn.

Smiling is a signaling system that evolved from a need to communicate information of many different forms. One of these is advertisement of sexual interest. Female smiles are appealing to heterosexual males, increasing physical attractiveness and enhancing sex appeal. However, recent research indicates a man's smile may or may not be most effective in attracting heterosexual women, and that facial expressions such as pride or even shame might be more effective. The researchers ignored the role of smiles in other sexual preferences.