Authentic smiles predict well-being, happy marriages, and long lives.
But the thing is, they're un-fakeable.
The Association for Psychological Science sketches out the physiological reasons why:
A smile begins in our sensory corridors. The ear collects a whispered word. The eyes spot an old friend on the station platform. The hand feels the pressure of another hand.
This emotional data funnels to the brain, exciting the left anterior temporal region in particular, then smolders to the surface of the face, where two muscles, standing at attention, are roused into action: The zygomatic major, which resides in the cheek, tugs the lips upward, and the orbicularis oculi, which encircles the eye socket, squeezes the outside corners into the shape of a crow’s foot.
It's these two muscles in your face — the zygomatic major and the orbicularis oculi— that work together to create real-deal grins. The key is in that skin around your eyeballs: when you're really smiling, the crow's feet form. When you're faking it, they don't.
In the psych racket we call the real-deal grin a Duchenne smile, named for 19th-century French anatomist Guillaume Duchenne. He's proof that medicine used to be even weirder: Dude liked to investigate the way people express emotions by zapping muscles with electrodes. Legend has it he tested his theories out on the severed heads of criminals. (Talk about going head first into your research.)
Duchenne wrote of the difference between real and fake smiles in his 1862 book "Mecanisme de la Physionomie Humaine." As the APS reports, Duchenne wrote that while you can will the zygomatic major to work — what we're talking about when we force a smile— only the "sweet emotions of the soul" make the orbicularis oculi activate, causing those crow's feet.
Duchenne's research would inspire Darwin's investigations into emotions, but then lay neglected until smile research started up again in the last few decades.
The results will make you grin, or maybe wince.
In a 2001 study, University of California at Berkeley psychologists LeeAnne Harker and Dacher Keltner analyzed the yearbook photos of women at the age of 21 and compared that info with personality data in a 30-year longitudinal study. The result: women who expressed greater levels of positive emotion — had those toothy, crow's-footy grins — reported higher general well-being and more satisfaction in their marriages than those who smiled weakly at age 52.
"People photograph each other with casual ease and remarkable frequency," the authors write, "usually unaware that each snapshot may capture as much about the future as it does the passing emotions of the moment."
The research suggests that your smiles also predict your lifespan. In a 2010 study, Wayne State University psychologists Ernest Abel and Michael Kruger compared the smiliness of baseball players in photos from 1952, then paired that with the player's age of death. The smile intensity of the player correlated with their likelihood of still being alive. "In any given year," the APS reports, "players with Duchenne smiles in their yearbook photo were only half as likely to die as those who had not."
Even more intriguingly, we learn the false-real smile difference when we're super tiny: at just 10 months old, an infant will give a false smile to a stranger, but offer up a sincere, eye-crinkly to mom.
The takeaway, then, is to treasure those magical crow's feet — since they signal a long life, quality relationships, and heartfelt happiness.