A Natural History of Rape: Biological Bases of Sexual Coercion. - Review - book review

Journal of Sex Research,  Feb, 2001  by Todd K. Shackelford,  Gregory J. LeBlanc

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Having clarified the importance of evolution to understanding life, Thornhill and Palmer note that, "Evolutionary theory applies to rape, as it does to other areas of human affairs, on both logical and evidentiary grounds. There is no legitimate scientific reason not to apply evolutionary or ultimate hypotheses to rape. The only scientific question concerns how to apply theoretical biology to a particular aspect of human endeavors. Evolutionary history would be applicable to human rape even if it were explicable only as a trait that exists as a result of evolutionarily novel circumstances faced by modern humans. And if such were the case, one would still want to know why men's psychological adaptations are designed in a way that yields rape behavior in the novel circumstances" (p. 55).

In later sections of the book, Thornhill and Palmer debunk the hypothesis that rape is entirely attributable to evolutionarily novel circumstances, citing evidence such as the cross-cultural incidence and prevalence of rape. Thornhill and Palmer address and dismiss with convincing empirical and theoretical evidence several ultimate hypotheses for rape including, for example, that rape is a "phylogenetic holdover"--that is, that males rape because they are descendants of males who raped. Thornhill and Palmer conclude that, "There are currently only two likely candidates for ultimate causes of human rape: It may be an adaptation that was directly favored by selection because it increased male reproductive success by way of increasing mate number. That is, there may be psychological mechanisms designed specifically to influence males to rape in ways that would have produced a net reproductive benefit in the past"(p. 60).

The second hypothesis, the "byproduct hypothesis," is that, "[Rape] may only be a product of other psychological adaptations, especially those that function to produce the sexual desires of males for multiple partners without commitment. In this case, there would not be any psychological mechanism designed specifically to influence males to rape in ways that would have produced a net reproductive benefit in the past" (p. 61). Much of the remainder of the third chapter, and various sections throughout the remainder of the book, present the empirical and theoretical work supportive of and contrary to each of these hypotheses. Thornhill and Palmer take the reader on a fascinating scientific and intellectual journey as they consider the status of the two competing evolutionary hypotheses for rape. Thornhill and Palmer clearly note for the reader, however, that both hypotheses remain viable, and that future empirical work is required to resolve which hypothesis better describes reality.

In chapter four, "The Pain and Anguish of Rape," Thornhill and Palmer review the mounting empirical evidence that the psychological pain of rape is adaptively patterned. Consistent with recent advances in the evolutionary psychology of psychological pain (see, for example, Nesse & Williams, 1994), Thornhill and Palmer argue that psychological pain occurs following "events that lowered reproductive success in human evolutionary history," (p. 86) and that, "The greater the negative effect [on reproductive success] of an event, the greater the psychological pain experienced" (p. 86). These hypotheses lead to several novel and nonintuitive predictions about the psychological pain felt by rape victims.