Turns everything you thought you knew about sex on its head. A bold and unashamed assessment of the plentiful scientific data that illuminate the true origins and nature of human sexuality. Funny, engaging, and superbly written, Sex at Dawn explores the science behind what many of us suspected all along: human beings are not naturally monogamous. Julie Holland, M.D., author of Weekends at Bellevue Since Darwins day, weve been told that sexual monogamy comes naturally to our species. Mainstream science-as well as religious and cultural institutions-have maintained that men and women evolved in families in which a mans possessions and protection were exchanged for a womans fertility and fidelity. But this narrative is collapsing. Fewer and fewer couples are getting married and divorce rates keep climbing as adultery and flagging libido drag down even seemingly solid marriages. How can reality be reconciled with the accepted narrative? It cant be, according to renegade thinkers Christopher Ryan and Cacilda Jethá. While debunking almost everything we know about sex, they offer a bold alternative explanation in this provocative and brilliant book. Ryan and Jethás central contention is that human beings evolved in egalitarian groups that shared food, child care, and often, sexual partners. Weaving together convergent, often overlooked evidence from anthropology, archeology, primatology, anatomy, and psychosexuality, the authors show how far from human nature monogamy really is. Turns out, human beings everywhere and in every era have confronted the same familiar, intimate situations in surprisingly different ways.