Paul Ekman - The Universality of Emotions

Social constructivism and relativism, the views that human behaviors, expressions, beliefs and attitudes are relative to and determined by culture, dominated much of the social sciences and humanities during the twentieth century. These approaches to the understanding of humanity relied on a mistaken presupposition: that the mind starts out as a blank slate upon which experience alone imprints information and the context to respond to it.

The problem, of course, as Darwin had already demonstrated in the nineteenth century, is that we are not merely social creatures: we are biological creatures whose minds have been tinkered by the process of natural selection over eons of time.

This dichotomy created two testable hypotheses: if social constructivism were true, then there should be no universal traits between cultures that have never interacted with each other (after all, social constructivism is the view that all traits are ultimately arbitrary and contingent on the particular history of a given population); if evolution were true, however, there should be, despite all the apparent differences, some set of recognizable facial expressions that reveal universal emotions, no matter where the subjects may come from.

Enter Paul Ekman, the man who finally solved this mystery and who has started the scientific study of facial expressions through his facial action coding system (FACS), which is based on the idea that human emotions can be inferred directly from the combination of facial muscles that give rise to facial expressions. His work has evolved to study microexpressions: involuntary and quick muscle cues that reveal a subject's real state of mind. This is one dude you do not want to lie to...

Yes, in case you're wondering, Lie to Me was based on Ekman's work.
.