Why do we marry? Why are some people adulterous? Why do human beings divorce? What is infatuation? When did human love and sex evolve, and what is the future of the family? In this brilliant book anthropologist Helen Fisher examines the innate aspects of sex and love and marriage, those traits and tendencies that we inherited from our past. She examines flirting behavior and the other courting postures and vocal tones we use naturally to court each other. She explains love-at-first-sight and why we fall in love with one person rather than another. She explores the brain chemistry of attraction and attachment. And she looks at divorce in 62 societies and adultery in 42 cultures to illustrate her new theory, the "four-year itch". Fisher traces the evolution of human courtship, marriage, adultery, divorce, re-marriage, and the sexual emotions back to their origins on the grasslands of Africa four million years ago. Women, men, and power, the genesis of teenage, the origin of human conscience, gender differences in the brain, and many other aspects of human sexuality take on new meaning as she follows human-kind from caves in Africa through the agricultural revolution and on into contemporary Western social life. In the last chapter, Fisher looks at several modern trends and concludes that many are not new. Instead, these family patterns came across the centuries, up from primitives who wandered out of Africa millennia ago.