Researchers have discovered a link between big smiles in old photos and durable contentment in older marriages. To arrive at the curious correlation, they rated the intensity of smiles in childhood snapshots and school yearbooks. Then they checked to see which participants had divorced and which had stayed married. You already know the results. “Maybe smiling represents a positive disposition toward life,” study leader Matthew Hertenstein, a psychologist at DePauw University in Indiana, told LiveScience. “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.” Whatever it is, the world needs more of it. Young people: Say cheese!