“The beast came out of him!” This is what we say when someone does evil. But why not when they do good? Frans de Waal addresses this question, exploring the biological foundations of one of humanity's most valued traits: morality.

Based on a series of lectures at Princeton University, the book includes comments made by philosophers Peter Singer, Christine M. Korsgaard, Philip Kitcher, and science writer Robert Wright. This provocative book argues that modern evolutionary biology adopts an overly gloomy view of the natural world, emphasizing our “selfish” genes.

Science thus exacerbates our double habit of blaming nature for our bad actions and labeling whatever good we do as “human”: by seeking the origin of morality not in evolution but in human culture, it insists that we are moral by choice and not by nature.

Offering impressive evidence from his extensive research on primate behavior, de Waal counters the “blank slate theory,” which posits that morality is nothing but a thin veneer over an otherwise wicked nature.

Drawing from both Darwin and recent scientific achievements, he recognizes the continuity between human and animal behavior and explains how we evolved from a long line of animals that care for their weak members and engage in cooperation through mutual exchanges.