Maggie Scarf, a journalist who specializes in the behavioral sciences, here presents a collection of her pieces surveying the controversial frontiers of psychology. In Scarf's lucid, lively portrayal, this rapidly evolving science becomes a parade of intriguing unanswered questions: When does a fetus become a person? To what extent do fetal sex hormones program adult behavior? What causes hangovers? (Surprisingly, nobody really knows.) Why do we need sleep? (Nobody knows that, either, though a great deal is being discovered about how we sleep.) What is ""normal"" or ""sane""? (The answer seems to be largely a matter of cultural context and interpretation.) For every frontier there is a pioneer, and Scarf's method is often to interview or profile a prominent innovator, then consult with at least one of his or her critics for a balanced estimation. In this manner she introduces us to Jane Goodall of chimpanzee fame; Dr. John Bowlby, who has applied animal ethology to the study of human mother-child attachments; the slightly chilling Jose Delgado, who controls animals' behavior by electrical brain stimulation; psychiatric radicals R. D. Laing and Thomas Szasz. She also brings to life ordinary individuals who illustrate the problems of manic depression, suppressed anger, fear in cities, and female suicide. Scarf is a clear and responsible journalist who knows how to highlight her writing with a warm personal touch while keeping her own judgments in the background. Her book is an intelligent popular introduction to the range of new thinking on human behavior.