"If we really want to understand human nature, we will have to understand the history of evolution," says Joseph Ledoux, one of the world's leading neuroscientists. How did life appear on our planet? How did sexual reproduction come about? How did multicellular organisms emerge from unicellular organisms? How did nervous systems evolve? What do we know about consciousness and the brain? Joseph Ledoux takes a step-by-step look at each of the points, proving that the earliest single-celled organisms exhibited survival behaviors along with learning and memory abilities, and sees these mechanisms as key to understanding human behavior. Along the way, Ledoux demonstrates how the evolution of the nervous system made possible the emergence of beings with complex mental life, possessing what we call consciousness, but at the same time poorly understood; explores the origin and meaning of emotions, and explains why our conscious mind may be one of a kind.