Sapolsky opens Behave with recapitulating a fantasy he has had “since I was a kid” (2) of personally capturing Hitler during World War II and committing sadistic acts of violence against him as punishment for his atrocities. This is a startlingly dark and also comically self-effacing passage to begin a popular science book. However, in acknowledging that many would agree with leaving Hitler “paralyzed, but with sensation” (1) before torturing him, this passage illustrates “a central point of this book—we don’t hate violence. We hate and fear the wrong kind of violence, violence in the wrong context” (3). This book explores the biology of “right” and “wrong” human acts including aggression, violence, altruism, and self-sacrifice.

Sapolsky then moves to a second section, “The Approach in this Book” (4), in which the author outlines that this book will be purposefully cross-disciplinary, including endocrinological, neurobiological, and evolutionary explanations of human behavior. This is intended to create a holistic and readable approach to the complex topic that avoids common scientific quagmires of reducing behavior’s complexity to the findings possible in a single field.

In the third section of the Introduction, “Our Lives as Animals and our Human Versatility at Being Aggressive” (10), Sapolsky makes the point that most of human behavior has clear correlates in the animal kingdom.