In this innovative celebration of diversity and affirmation of individuality in animals and humans, Joan Roughgarden challenges accepted wisdom about gender identity and sexual orientation. A distinguished evolutionary biologist, Roughgarden takes on the medical establishment, the Bible, social science--and even Darwin himself. She leads the reader through a fascinating discussion of diversity in gender and sexuality among fish, reptiles, amphibians, birds, and mammals, including primates. "Evolution's Rainbow "explains how this diversity develops from the action of genes and hormones and how people come to differ from each other in all aspects of body and behavior. Roughgarden reconstructs primary science in light of feminist, gay, and transgender criticism and redefines our understanding of sex, gender, and sexuality. This is a witty, playful, and daring book that has revolutionized our understanding of sexuality.