A unique evolutionary perspective provides readers with the most extensively researched means to understand human sexual behavior. A wide range of powerful real-life case studies provides unique perspectives that present a more human view of sexual variations rather than one that is strictly clinical. Comprehensive coverage includes the history of sexuality; key theorists involved in developing approaches for working with individuals with sexual disorders; an overview of the modern approaches and schools of sexuality; the role of the Internet in changing sexual values; the biology and physiology of sexuality enhanced by the latest research in neuroscience; and more. Chapters on sexual variations include body image, arousal, gender variations, cultural views, anxiety, sexual crimes/violence, aging and sexuality, and recent trends. Novel models and illuminations of LBGTK sexualities help fully explain many aspects of sexual behavior that have been poorly understood. Close to a thousand references reflect the foundational and recent scholarship in the field to keep readers up to date. Interviews with the leaders in the field share the insights of evolutionary psychology co-founder and sexual aggression expert David M. Buss; renowned anthropological love researcher Helen Fisher; evolutionary sexuality pioneer Gordon Gallup; researcher into the evolutionary psychology of relationships Douglas Kenrick; Kinsey Institute Director and researcher C. Sue Carter; controversial reproductive scientist J. Philippe Rushton; author and transgender development clinician Diane Ehrensaft; prolific gender identity scientist Kenneth Zucker; evolutionary reproductive scientist Todd K. Shackelford; fear and anxiety scientist, researcher, and author Joseph LeDoux; and iconic memory and repression scientist Elizabeth F. Loftus.