"Researchers of human behaviour have identified an 'orgasm gap': Men usually orgasm during intercourse, whereas women often do not. This book addresses this mystery. The two leading explanations are either that women are "psychologically broken" - Freud's theory - or badly designed - the "by-product theory." However, there is a much more compelling third explanation. Evolutionary biology, anatomy, physiology, and direct sex research suggest women have evolved under their own selection pressures and orgasm is a fitness increasing consequence such selective factors. This is revealed in their patterns of orgasmic response, which are neither random, nor inexplicable"--