What makes a happy marriage? Scientists are studying why some people are happier in their marriages then others. They’re finding that personal growth, called “self-expansion,” has a lot to do with it. Stony Brook University social psychologist ARTHUR ARON studies marriage, social relationships, and romantic love. He’ll tell Marty some of the secrets to making and maintaining a happy, fulfilling marriages and relationships. Also, LARRY YOUNG, a professor of psychiatry at Emory University, explains what we can learn from a small rodent, the prairie vole, about bonding, monogamy, and love.