Psychologists have found that how much people smile in old photographs can predict their later success in marriage.
In one test, the researchers looked at people's college yearbook photos, and rated their smile intensity from 1 to 10. None of the people who fell within the top 10 percent of smile strength had divorced, while within the bottom 10 percent of smilers, almost one in four had had a marriage that ended, the researchers say. (Scoring was based on the stretch in two muscles: one that pulls up on the mouth, and one that creates wrinkles around the eyes.)
While the connection is striking, the researchers stress that they can't conclude anything about the cause of the correlation.
"Maybe smiling represents a positive disposition towards life," said study leader Matthew Hertenstein, a psychologist at DePauw University in Indiana. "Or maybe smiling people attract other happier people, and the combination may lead to a greater likelihood of a long-lasting marriage. We don’t really know for sure what's causing it."
Hertenstein said he has considered other explanations, such as the possibility that people who smile more often tend to attract more friends, and a larger support network makes it easier to keep a marriage healthy.
The study is detailed in the April 5 issue of the journal Motivation and Emotion.