What are the facial expressions? The question may seem absurd in the present human context, as anyone knows the answer. But at some point in the evolution should arise, and that has been perpetuated in humans shows that somehow were useful to help our ancestors survive.
The basic idea comes from a new study by Jessica L. Tracy, University of British Columbia in Canada, and Azim F. Sharif University of Oregon in the U.S., is that facial expressions are typical of each particular emotion which were developed for a specific reason, not chance.
The usefulness of the expression of fear perhaps the most evident. Open his eyes helps us better see the danger that threatens us, and also alerts people around us that we have detected something dangerous.
The expression of disgust makes it harder to breathe in something toxic in the air.
The physical expression of pride (or arrogance), with the standing figure, to maximize lung capacity, which in turn helps build physical activity required for intense fight with a rival.
In more recent times, as social life became more important to the evolutionary success of certain species, including human, expressions evolved to serve a social function and a smiling face, for example, reports no threat, and a face that blushes of shame communicates his desire to appease the person who has done something wrong.
The research of Shariff and Tracy is partly based on work of recent decades that have shown that some emotional expressions are universal, even in remote areas with no exposure to Western influences, people know what a look of fear and sadness. Evidence of this type indicate that it is unlikely that expressions arise sometime in the past as social devices invented in Europe, which then propagate the rest of the world.
And not just across cultures but also across species. Shariff argues that there are different expressions common to all individuals, including pride, in chimpanzees and other apes. This suggests that expressions appeared even before the human being, being a useful resource for evolutionary common ancestor of apes and humans.