The third edition of Principles of Animal Behavior aims to show why—by building on the work in the frst two editions of this book and adding the latest, best, cuttingedge research being done in animal behavior. Much has happened in the feld of animal behavior since the last edition of this book was published in 2009. Recent research fndings have given me ample opportunity not only to update and expand on the studies presented in the book but also to reinforce the previous editions’ focus on ultimate and proximate causation, as well as the book’s unique emphasis on natural selection, learning, and cultural transmission. But there is more to this new edition of Principles of Animal Behavior than that