For a long life, smile like you mean it
13:26 05 March 2010 by Ewen Callaway
If you want to live to a grand old age, then smile – and make sure you mean it. Pro baseball players in the 1950s who genuinely beamed in their official photographs tended to outlive more sullen-looking sportsmen and those who put on fake smiles.
Players from the US major league with honest grins lived an average of seven years longer than players who didn't smile for the camera and five years longer than players who smiled unconvincingly, conclude Ernest Abel and Michael Kruger at Wayne State University in Detroit, Michigan.
It's known that happy people tend to be healthy too. Kruger and Abel wondered whether this relationship would be reflected in the smiles and longevity of baseball players.
Genuine smiles are known as Duchenne smiles after the 19th-century neurologist who defined them in detail. They engage muscles both near the corners of the mouth and around the eyes – the zygomatic major and the orbicularis oculi respectively. Fake, "non-Duchenne" smiles exercise only mouth muscles.
With training, these muscles are easy to recognise in photographs. So Abel and four colleagues who were not aware of what the study was investigating, but were trained to analyse smiles, looked at vintage photographs of 230 major leaguers who played in the 1952 season. The researchers classified them as non-smilers, Duchenne smilers or non-Duchenne smilers. Then they looked up the lifespans of the 184 players who had already died.
They found that out of the dead players, Duchenne smilers had tended to live the longest, followed by non-Duchenne smilers. And after accounting for other factors that tend to predispose people to longevity, such as a university education and good health, they found an even firmer link between strength of smile and length of life.
People who didn't smile had just a 50 per cent chance of surviving to 80, all other things being equal, whereas those with Duchenne smiles had about a 70 per cent chance of surviving to this age. Overall, 35 per cent of the differences in lifespan correlated with smile intensity.
Abel and Kruger conclude that people who smile genuinely in photographs "may be basically happier than those with less intense smiles", making them more likely to experience the health benefits of happiness, which has been linked with lower levels of stress hormones and a protein implicated in heart disease.
Is a smile in a photograph really a good measure of overall happiness? Not necessarily, but the results don't come out of left field, say Wallace Friesen and Deborah Danner, psychologists at Sanders Brown Center on Aging in Lexington, Kentucky: previous studies have found links between genuine smiles in photographs and overall happiness and marital satisfaction.
Matt Hertenstein, a psychologist at DePauw University in Greencastle, Indiana, adds that smiling in a photo may not simply reflect happiness: people who are conscientious might be more willing to heed a photographer's request to "say cheese", and conscientiousness has also been linked to longevity.
Alternatively, players who smiled could be more sociable than others. "A long line of work indicates that greater and deeper social networks increase well-being and longevity in life," he says.
Increased conscientiousness and stronger social networks could also explain why non-Duchenne smilers – those who made an effort to smile, albeit unconvincingly – lived longer than those who didn't smile at all.
Journal reference: Psychological Science, DOI: 10.1177/0956797610363775