Sex at Dawn: The Prehistoric Origins of Modern Sexuality is a 2010 book about the evolution of human mating systems by Christopher Ryan and Cacilda Jethá. In opposition to what the authors see as the "standard narrative" of human sexual evolution, they contend that having multiple sexual partners was common and accepted in the environment of evolutionary adaptedness. The authors contend that mobile, self-contained groups of hunter-gatherers were the norm for humans before agriculture led to high population density. Before agriculture, according to the authors, sex was relatively promiscuous and paternity was not a concern. This dynamic is similar 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 were 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. Conversely, numerous scholars from related academic disciplines—such as anthropology, evolutionary psychology, primatology, biology, and sexology—have been highly critical of the book's methodology and conclusions, although some have commended its arguments.
Summary The 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. The authors believe that much of evolutionary psychology has been conducted with a bias regarding human sexuality. They argue that the public and many researchers are guilty of the "Flintstonization" of a hunter-gatherer society, i.e. projecting modern assumptions and beliefs onto earlier societies. Thus the authors believe that there is a false assumption that our species is primarily monogamous and offer evidence to the contrary. They argue, for example, that our sexual dimorphism, testicle size, female copulatory vocalization, appetite for sexual novelty, various cultural practices, and hidden female ovulation, among other factors strongly suggest a non-monogamous, non-polygynous history. The authors argue that mate selection among pre-agricultural humans was not the subject of intragroup competition as sex was neither scarce nor commodified. Rather, sperm competition was a more important paternity factor than sexual selection. This behavior survives among some remaining hunter-forager groups that believe in partible paternity.
The authors argue as a result that conventional wisdom regarding human nature, as well as what they call the standard narrative of evolutionary psychology, is wrong. Their version of the "standard narrative" goes like this: Males and females assess the value of mates from perspectives based upon their differing reproductive agendas/capacities. According to the authors:"[The male] looks for signs of youth, fertility, health, absence of previous sexual experience, and likelihood of future sexual fidelity. In other words, his assessment is skewed toward finding a fertile, healthy young mate with many childbearing years ahead and no current children to drain his resources. She looks for signs of wealth (or at least prospects of future wealth), social status, physical health, and likelihood that he will stick around to protect and provide for their children. Her guy must be willing and able to provide materially for her (especially during pregnancy and breastfeeding) and their children (known as male parental investment)."Assuming the male and female meet each other's criteria, they mate and form a monogamous pair bond. Following this"she will be sensitive to indications that he is considering leaving (vigilant toward signs of infidelity involving intimacy with other women that would threaten her access to his resources and protection)—while keeping an eye out (around ovulation, especially) for a quick fling with a man genetically superior to her husband. He will be sensitive to signs of her sexual infidelities (which would reduce his all-important paternity certainty)—while taking advantage of short-term sexual opportunities with other women (as his sperm are easily produced and plentiful)." In human mating behavior, the authors state that "we don't see [current mating behaviors] as elements of human nature so much as adaptations to social conditions—many of which were introduced with the advent of agriculture no more than ten thousand years ago." The authors take a broad position that goes beyond sexual behavior, arguing that humans are generally more egalitarian and selfless than is often thought. In an interview, Ryan said, "So we're not saying that sharing was so widespread because everyone was loving and sitting around the fire singing "Kumbaya" every night. The reason that sharing was so widespread—and continues to be in the remaining hunter-gatherer societies in existence—is because it's simply the most efficient way of distributing risk among a group of people." However, the Neolithic Revolution led to the advent of private property and the accumulation of power and completely changed people's lifestyles. This change in lifestyle fundamentally altered the way people behave and has left modern humans in a situation where their instincts are at odds with the societies in which they live. The authors do not take an explicit position in the book regarding the morality or desirability of monogamy or alternative sexual behavior in modern society but argue that people should be made aware of our behavioral history so that they can make better-informed choices.
Reception
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