Anthropologist Helen Fisher studies gender differences and the evolution of human emotions. She’s one of the world’s best known experts on romantic love.

At a TED talk, Fisher delves into the tricky topic of love and explains its evolution, its biochemical foundations and its social important. Most importantly, Fisher explains plainly why we love, why we cheat, and what the characteristics of love are.

Fisher reveals that romantic love is not an emotion. In fact, it is a drive. “It comes from the motor of the mind, the wanting part of the mind, the craving part of the mind. The kind of mind — part of the mind — when you’re reaching for that piece of chocolate, when you want to win that promotion at work. The motor of the brain. It’s a drive.”

Watch the video below to learn more about what love is: