The wider you smile, the longer you'll live, according to psychologists from the University of Kentucky (USA). The researchers asked volunteers to categorize 230 photographs of Major League Baseball players from the 1952 roster by the width and openness of their smiles. The results were divided into three groups: those who smiled “heartily,” those who smiled “routinely,” and those who simply grinned.
It turned out that those who didn't smile lived an average of 73 years. Those with the “Pan Am” smile (called it “Pan Am” after the flight attendants of the famous airline who always smile with their teeth, not their eyes) died, on average, at age 75. Meanwhile, those with the “Duchenne smile” (which involves the entire face, and the term comes from the French scientist who first described in detail the physiology of a genuine smile) lived, on average, around 80 years.
Of course, it's not just the smile itself. Optimism and a positive outlook on life influence the production of hormones that improve the immune system, heart, and blood vessels. However, people with a pessimistic outlook on life are less able to fight viral infections and are more likely to suffer from gastrointestinal diseases and nervous disorders.
Incidentally, two types of smiles are common to all humans. As early as 10 months, most babies smile with a “Pan-American” smile when meeting a stranger and a “Duchenne” smile when interacting with their mother.