Evolution, not culture, deserves blame for rape

At Yale, rape is allegedly more common than the university lets on. Whether this charge is true or not, ethnographers have yet to discover a community of Homo Sapiens in which rape does not occur [1, 2, 3]. In the interest of promoting human flourishing, we have a common obligation to identify the causes of this crime and suppress them.

Students and administrators at Yale have made progress in this regard, from the orientation skit “Sex Signals” to the establishment of the Rape and Sexual Violence Prevention (RSVP) group. While an earnestness to prevent sexual assault should get unqualified support, outside of elementary school, good effort isn’t good enough. To date, these operations (excluding parts of “Sex Signals”) are heavy on sound and fury but light on significance. In order to prevent rape, a thorough debate of its causes is required, and so far this has not happened.

An article on rape prevention posted on the Yale Web site argues that sexual assault is “an extension of a male-dominated society’s control over females,” that it is a transmitted culturally, and that it is a “myth” that rape has anything to do with sex [5]. Moreover, the authors claim that it is “false” to say that rape victims are “usually young, attractive women.” This is flatly untrue and is directly contradicted many times in the literature [1, 6, 7].

And yet these mantras have been repeated like Talmud in recent and not-so-recent editorials in this paper, which attribute rape to acculturated misogyny, an absence of “consciousness raising” and the failure to think of men and women as identical copies of one another with no differences whatsoever.

The data do not support the conclusion that rape is a crime about violence and domination and not sex. If this were true, one would expect most victims to be either old or young — the two groups of women least able to protect themselves from attack. On the contrary, most rape victims are young women in their prime reproductive years [1, 6, 8].

The most parsimonious explanation for this age distribution among victims is that these women are most sexually attractive to males, and the evidence suggests that natural selection, which has equipped men with a psychological apparatus designed to maximize the total number of female copulations, may lead them to rape as a byproduct of this tendency or, frighteningly, because in certain environmental conditions, rape is a behavior that enhances reproductive success [1]. This latter notion, however repugnant, is consistent with the observed phenomenon of out-group rape, in which members of a human band are encouraged to rape, and spare, the women of the enemy during times of war, but are forbidden to rape women in their own community [1, 9, 10].

Perhaps the most informative insight into rape, however, comes from the meticulous work of zoologists and animal behaviorists. In non-human species, it is possible to study the incidence and significance of rape after taking culture out of the equation. Indeed, rape is common in the animal kingdom, and is observed in insects, 39 species of birds, reptiles, fish, marine mammals and the great apes [1]. Some organisms, like the scorpionfly and the waterstrider, have evolved specific appendages for committing rape, and in these situations, it appears to be an adaptive behavior initiated in response to particular environmental conditions [1,11]. Similarly, our close evolutionary relatives, the orangutans, consist of dominant and subordinate males, and the subordinates reproduce by raping unguarded females. It is estimated that between one-third and one-half of orangutan copulations are rapes [1, 3].

Of course this is not to say that humans are scorpionflies or orangutans, but it does prove the point that rape can be an adaptation, and that in the vast majority of the animal world — our world — rape occurs with regularity in the absence of cultural factors.

The upshot of this discussion is that most of what we are taught about the causes of rape is wrong. Many men and other animals are very prone to rape females if they feel that there is little cost for doing so, and that it is highly unlikely that this biological tendency can be trained out of people. Therefore, preventing rape must be accomplished by reducing the number of situations in which men are able to use coercive sex without much risk of being punished, recognizing that rape really is about sex and informing men and women about sex differences and the evolutionary origins of sexual coercion. Examples of possible interventions include discussions on how men use alcohol and marijuana as pharmacological tools to facilitate rape; chaperones; and even stronger advice that being alone with a man, particularly after consuming drugs and/or alcohol is a high-risk behavior.

As it is for so many of the human miseries, we ought to be blaming evolution for producing a male sexual psychology that is prone to rape, and to a much lesser extent — if at all — culture. Until this happens, the ongoing tragedy on our campus will continue in full force.



Matthew Gillum is a first-year graduate student in molecular and cellular physiology.



1. Thornhill, R.a.P., Craig T., A Natural History of Rape: The Biological Bases of Sexual Coercion. 2000, Cambridge, Massachusetts: The MIT Press.

2. Palmer, C., Is rape a cultural universal? A re-examination of the ethnographic evidence. Ethnology, 1989. 28: p. 1-16.

3. Wrangham, R.a.P., D. , Demonic Males: Apes and the Origins of Human Violence. 1996: Houghton Mifflin.

4. Jones, O., Sex, culture and the biology of rape: Toward explanation and prevention. California Law Review, 1999. 87: p. 827-942.

5. Cohen, M.a.M., Sherrie H. , Rape: Psychology, Prevention and Impact. Unknown, Yale University/Yale-New Haven Teachers Network.

6. Perkins, C.a.K., P. , Criminal Victimization 1994. National Crime Victimization Survey. , U.D.o. Justice, Editor. 1996, Bureau of Justice Statistics.

7. Kilpatrick, D., Edmunds, C and Semour, A. , Rape in America: A Report to the Nation. 1992, National Victim Center: Arlington, VA.

8. Perkins, C.a.K., P., Bastian L., and Cohen, R, Criminal Victimization in the United States, 1993. National Crime Victimization Survey. , U.D.o. Justice., Editor. 1996, Bureau of Justice Statistics.

9. Hartung, J., Getting real about rape. Behavioral and Brain Sciences, 1992. 15: p. 390-392.

10. Shields, W.a.S., L. , Forcible Rape: An evolutionary perspecitve. Ethology and Sociobiology, 1983. 4: p. 115-136.

11. Sakaluk, S., Bangert, P., Eggert, A., Gack, C., and Swanson, L. , The gin trap as a device facilitating coercive mating in sagebrush crickets. . Proceedings of the Royal Society of London, 1995(261): p. 65-71.

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