Sex at Dawn: The Prehistoric Origins of Modern Sexuality is a book dealing with the evolution of monogamy in humans and human mating systems. First published in 2010, it was co-authored by Christopher Ryan, PhD and Cacilda Jethá, MD. In opposition to what the authors see as the 'standard narrative' of human sexual evolution, they contend having multiple sexual partners was common and accepted in the environment of evolutionary adaptedness. Mobile self-contained groups of hunter gatherers are posited as the human norm before agriculture led to high population density. According to the authors, before agriculture, sex was relatively promiscuous, and paternity was not a concern, in a similar way to the mating system of Bonobos. According to the book, sexual interactions strengthened the bond of trust in the groups; far from causing jealousy, social equilibrium and reciprocal obligation was strengthened by playful sexual interactions.The book generated a great deal of publicity in the popular press, where it was met with generally positive reviews. A number of scholars from related academic disciplines such as anthropology, evolutionary psychology, primatology, biology, and sexology have commented on the book; many have been critical of the book's methodology and some of its conclusions, although some academics have praised the book.SummaryThe authors argue that human beings evolved in egalitarian hunter-gatherer bands in which sexual interaction was a shared resource, much like food, child care, and group defense.