The unfortunate prevalence of the "impulse" model has been fostered, in part, by the recent resurgence of more sophisticated biological theories of sexual assault. These theories assert that while there is no "gene" that causes men to rape, the existence of a predisposition to rape may be a consequence of evolution. According to this theory, men who are predisposed to rape may have more reproductive success (such as a higher number of offspring). Over long periods of time, this reproductive advantage results in a widespread predisposition to rape among males. Other theorists argue that predisposition to rape is not an adaptation itself, but the side-effect of reproductive adaptations, such as the pursuit of a number of partners.

Paired with these biological explanations of the perpetrator's behavior have been biological explanations of the behavior of a victim of sexual assault. For women, sexual activity with a limited number of partners is desirable and thus women have evolved to resist rape. Further, these theorists argue, the experience of "trauma" associated with sexual assault was a reproductively successful response because women who experienced such trauma subsequently avoided being raped.

Although some biological theorists maintain that acknowledging a biological basis for rape does not excuse rape, such theories can contribute to and perpetuate beliefs that excuse perpetrators from responsibility their actions and blame the victims. For example, some proponents of biological theories argue that because men cannot control their irresistible impulses to rape, it is women's responsibility to avoid dressing provocatively. According to this view, women who are raped must have put themselves in circumstances that led to rape and the appropriate response is to teach them how to avoid being raped.

Biological explanations for rape also tend to "naturalize" the perpetrator's behavior—thus leading to the conclusion that it is "acceptable" and potentially unchangeable. These theories also diminish the victim's pain and suffering. Further, biological theories have significant implications for criminal justice responses to rape. If rape is a biological adaptation, responses should include monetary penalties; further, such theories would call for chemical castration or hormonal treatments that can themselves constitute human rights violations. Finally, biological theories also lack explanatory power—they do not explain why men rape women who cannot bear children, or why they rape their intimate partners and spouses.

Adapted from Owen D. Jones, Sex, Culture, and the Biology of Rape: Toward Explanation and Prevention, 87 Cal. L.R. 827 (1999); Randy Thornhill, The Biology of Human Rape, 39 Jurimetrics J. 137, 143 (1999), excerpts available from the Berkman Center for Internet & Society at Harvard Law School; Susan Hansen, Review, A Natural History of Rape: Biological Bases of Sexual Coercion, Randy Thornhill & Craig T. Palmer 10(2000); Sharon Araji, Review, A Natural History of Rape: Biological Bases of Sexual Coercion, Randy Thornhill & Craig T. Palmer (2000); Diane Boudreau, Code to Violate?, ASU Research E-Magazine (2000).