“When you’re smiling,” Louis Armstrong (and dozens since) sang, “when you’re smiling, the whole world smiles with you.” More than 80 years later, scientists are getting around to proving that Larry Shay, Mark Fisher, and Joe Goodwin’s lyrics were more than just a pleasant homily. All thanks to an ancient evolutionary development called “mirror neurons.”
Italian researchers in the 1990s first found brain cells of macaques, which fire when they see another macaque reach for something. Since then, the “mirror” nerve cells have been found in a variety of mammals, from cats and dogs to you and I. These neurons brain respond equally whether we perform an action or witness someone do it. Including smiling.
So, smiles really are contagious – and so, it seems are the good feelings they signal. When you smile, two muscles jump into action: the zygomatic major pulls the edges of your lips upward, and the orbicularis oculi around the eye socket squeezes, making the infamous crow’s feet. The combination, what psychologists call a “Duchenne smile,” is the only authentic indicator of real enjoyment. (When people talk about seeing a smile in your eyes, that’s why.)
Maybe even more important, researchers over the last 20 years have shown that your facial expressions can actually change how good you feel. In 1989, Robert Zajonc had experimental subjects repeat vowel sounds that pushed their mouths into different expressions. Saying a long-E sound, which mimics smile reflexes. Reported feeling good, while those making the frowny long-U felt bad. In 2010, Kraft and Pressman took it one step further. Using chops sticks to shape the face, they found people forced to smile recovered faster from stress. And psychologists in Cardiff, Wales, found that when people had Botox injections that made it harder to frown, their mood improved, as well.
And, yes, they did rule out being happy about the effects of the Botox injection.