Helen Fisher knows a thing or two about relationships. The Kinsey Institute research fellow and Match.com’s lead scientific advisor has spent her career studying couples and romantic behavior. The author of six books, her writing traces human family life from its origins in Africa over 20 million years ago to the internet dating sites and bedrooms of today. Her cutting-edge research, using brain imaging, examines what love and romantic partnership does to our gray matter. In this episode, she explains why humans fall in love and form pair-bonds when the odds are against them.