Intended for the general reader as well as specialists, this book presents a fascinating new theory that posits three major brain types created by sex hormones before birth-Polytropic, Middle, and Focal. A brief scientific background is given first, and then the theory is illustrated with vivid anecdotes about real cases. The author argues persuasively (and sometimes startlingly) that brain types influence many human traits and differences, such as personality, special skills, learning disabilities, and a whole host of medical conditions. This unique approach promises new (and practical) insights into such puzzling issues as hyperactivity, autism, nicotine addiction, cancer, Alzheimer's disease, and dyslexia. Read this book to find out which kind of "zebra brain" you have and discover unique insights into you and everyone you know.