Craig T. Palmer

A Natural History of Rape: Biological Bases of Sexual Coercion is a 2000 book by biologist Randy Thornhill, a Regents' Professor of Biology at the University of New Mexico , and anthropologist Craig T. Palmer, an instructor in evolutionary anthropology , which argues that rape in humans has evolved as a reproductive strategy shaped by natural and sexual selection , either as a direct adaptation or a by-product of traits favoring male mating success through coercion when consensual access to fertile females is denied. The authors draw on comparative evidence from nonhuman animals, where sexual coercion is widespread, and human data patterns—such as elevated victimization rates among women of peak fertility—to support the claim that rapists are primarily driven by sexual motives rather than nonsexual factors like dominance or pathology.

The book critiques dominant social science perspectives that attribute rape solely to cultural learning, socialization, or misogynistic power structures, asserting these explanations fail to account for cross-cultural ubiquity, victim selection biases, and physiological responses inconsistent with nonsexual aggression, while privileging ideologically motivated denial of evolved sex differences in reproductive imperatives. Thornhill and Palmer advocate for prevention strategies informed by evolutionary insights, including heightened deterrence through punishment, early education of males on the biological costs of rape, potential use of chemical interventions to suppress deviant impulses, and female awareness of evolved male psychology to mitigate risks.

Upon release, the work ignited fierce debate in evolutionary psychology and beyond, praised by some for integrating empirical biology with behavioral realism to challenge unsubstantiated environmental determinism , yet lambasted by others for purportedly risking the normalization of sexual violence through genetic framing, though the authors explicitly reject any justificatory interpretation and emphasize causal understanding for harm reduction . Its reception highlights tensions between adaptationist hypotheses grounded in Darwinian mechanisms and constructivist paradigms prevalent in social sciences, where biological accounts often encounter resistance despite supporting data from victim demographics and animal analogs.

The core thesis of A Natural History of Rape asserts that human rape stems from evolved male psychological adaptations shaped by natural selection to enhance reproductive success, viewing it as a sexual behavior rather than solely a violent or pathological act. Authors Randy Thornhill and Craig T. Palmer argue that rape functions as a conditional reproductive strategy, activated when consensual mating opportunities are limited, and critique social science approaches for neglecting biological causation in favor of cultural or learned explanations. They posit that while rape could theoretically be a byproduct of adaptations for sexual desire and aggression, empirical patterns—such as rapists' preferences for fertile-aged victims and avoidance of pregnancy risks—better support it as a direct adaptation designed for coercive copulation.

This evolutionary framework emphasizes causal realism, prioritizing mechanisms like sperm competition and mate guarding over nurture-only models, and extends to female responses: post-rape trauma is hypothesized as an evolved psychological adaptation to minimize fitness costs from coerced insemination, such as paternal investment loss. Thornhill and Palmer maintain that recognizing these biological bases does not justify rape but enables more effective prevention by targeting evolved triggers, rather than assuming uniform pathology or societal constructs alone suffice.