I have found this to be an extremely useful book for introducing students to biological understandings of behavior. I have taught a course in Behavior and Religion, and found no better book with which to introduce laypeople to a biological perspective on altruism and related behaviors which often form the basis for what we consider to be matters of ethics and meaning. From the opening quotation from Robert Trivers ("Natural selection has built us, and it is natural selection we must understand if we are to comprehend our own identities . . .") the reader is forced to carry everyday logic to its obvious conclusion in assessing the cause and function of human behavior. This book has had a tremendous impact on the students in my classes, tumbling them into perhaps their first completely honest, knowing examination of their own meaning. I searched very hard for a book to present basic concepts in ethology to nonmajors, and this book was by far the best I found. Long may it remain in print!