What separates your mind from that of an animal? Is it the ability to design tools; a sense of self; or the grasp of past and future? In recent decades these claims have eroded, or even been disproven outright, by a revolution in the study of animal cognition. Waal explores both the scope and the depth of animal intelligence, offering a firsthand account of how science has stood traditional behaviorism on its head by revealing how smart animals really are, and how we've underestimated their abilities for too long.