"A controversial, idea-driven book that challenges everything you know about sex, marriage, family, and society"--Provided by publisher. Since Darwin's day, we've been told that sexual monogamy comes naturally to our species. But this narrative is collapsing. Here, renegade thinkers Christopher Ryan and Cacilda Jethá, while debunking almost everything we "know" about sex, offer a bold alternative explanation. Ryan and Jethá's central contention is that human beings evolved in egalitarian groups that shared food, child care, and, often, sexual partners. Weaving together convergent, frequently overlooked evidence from anthropology, archaeology, primatology, anatomy, and psychosexuality, the authors show how far from human nature monogamy really is. With intelligence, humor, and wonder, Ryan and Jethá show how our promiscuous past haunts our struggles over monogamy, sexual orientation, and family dynamics. Human beings everywhere and in every era have confronted the same familiar, intimate situations in surprisingly different ways. The authors expose the ancient roots of human sexuality while pointing toward a more optimistic future illuminated by our innate capacities for love, cooperation, and generosity.--From publisher description.