"Researchers analyzed photos taken in childhood or young adulthood from hundreds of people and rated their expressions on a "smile intensity score."
The less intensely the subjects smiled, the more likely they would be divorced later in life, while the biggest smilers had lower divorce rates, according to a study published online this month by the journal Motivation and Emotion.
Scientists don't know what accounts for the link, but say a smile may indicate higher levels of positive emotions and signal other traits, said co-author Matt Hertenstein, associate professor of psychology at DePauw University and head of the school's Touch and Emotion Lab.
"People who smile a lot may attract happier people and maybe happier marriage partners," Hertenstein said. "It may be that people who smile in response to a photographer are more obedient people and obedience may help in a marriage. I really don't know the explanation."
Before you run to check your spouse's yearbook photo, keep in mind one picture can't tell the whole story, Kaslow said.
"I think the issue really is both getting a sense of a whole set of pictures and also the level of positivity that [people] bring into life and relationships," she said."
What is your theory for why smilers get divorced less?