We smile for good reason. Studies show that it can elevate our mood, help us cope during hard times, and even increase the length of our lives. It has even been observed that we smile in the womb, and that at as young as ten months, we understand enough about smiling (at least instinctively) to present a stranger with a false smile, and reserve the real smile for people that we know. Researchers postulate that a smile serves to showcase the nonthreatening emotions we are feeling, like happiness. However, current neuroimaging data is at a loss for explaining to us exactly why we smile.
Dominance, submission, and smiles
Past studies have indicated that those who smile more often are also more prone to sharing and acts of altruism.
Interestingly enough, a smile in the primate world carries the opposite to a smile in the human world. When a primate bares their teeth, it is a sign of aggression or fright. The reigning theory is that as primates evolved, their teeth-baring also evolved into a more complicated displays of emotion.
In other species; a smile does not mean happy
Rhesus monkeys bare their teeth when confronted with a higher-ranking monkey. It is a sign of submission, and is demonstrated when the higher-ranking monkey has something that the lower-ranking monkey desires.
But what about a fake smile?
By evolutionary standards, being able to fake a smile is an advantage. But we’ve also grown to recognise the fake smile. The one muscle that conveys a smile’s sincerity is the orbicularis occuli, or, the outermost corners of our eyes, which causes us to squint. It’s what many people describe as “smiling with your eyes.” It has even been noted that those who smile more demonstrate a higher than normal propensity for sharing and cooperation.
Researchers even have a name for it; the “Duchenne smile;” named after the scientist who discovered it by attaching electrodes to people’s faces in order to stimulate their facial muscles.
Scientists hope to use this information to better understand the social purpose that our smile has evolved in to. Perhaps even discover how to better read people through fake versus genuine smiles.