Abstract
This book makes an important contribution to the fields of primatology, behavioral ecology, evolutionary psychology, and potentially even cultural anthropology. It grew out of presentations at the International Primatological Society, Annual Meeting in Entebbe, Uganda during June, 2006. Like many edited volumes resulting from conferences, this book has the excitement contained in the presentation of original cutting edge research. Its strength lies in the many chapters presenting findings from studies on a wide range of primate species, including orangutans, mountain gorillas, baboons, spider monkeys, and chimpanzees. What makes these chapters particularly valuable is that nearly all of them provide a superb discussion of the literature on other species, from dolphins to invertebrates, needed to situate the findings of each chapter within a larger comparative context. This makes the book of great potential value, even to researchers who study species that are not the explicit subject of this book.
Sexual Coercion in Primates and Humans also has a significant advantage over many conference proceedings; theoretical consistency. This consistency is based on the definition of sexual coercion presented by Smuts and Smuts (1993, pp. 2–3): “the use by a male of force, or threat of force, that functions to increase the chances that a female will mate with him at a time when she is likely to be fertile, and to decrease the chances that she will mate with other males, at some cost to the female.” The problem with this definition is that it is inconsistent with everyday parlance, in which evolutionary functions are irrelevant to what constitutes sexual coercion. A preferable alternative might have been to simply define key terms such as forced copulation, mate guarding, and infanticide in accordance with how these words are used in everyday life, and then separate these definitions from the discussion of the possible evolutionary functions of these behaviors. This is not a major criticism, however, because the chances of confusion over the definition of sexual coercion leading to serious misunderstandings are minimized by the frequent repetition of the Smuts and Smuts definition, which is cited in 17 of the 18 chapters, and the lone exception cites Smuts (1992). This enables readers to incorporate the individual chapters into a coherent explanatory framework. The strengths just described combine to make this book ideally designed for use in graduate or advanced undergraduate courses in a variety of disciplines. As a result, much of the future progress in evolutionary explanations of sexual conflict may have its roots in this volume.
Its only obvious weakness is in regard to human rape. Readers expecting detailed presentations of new hypotheses about the evolutionary cause of rape in Homo sapiens and the exact evidence that would support or falsify them will be disappointed. The hypothesis that human rape, or at least acquaintance rape, is an adaptation whose function is to increase the rapist's fitness over the “long term” by intimidating the victim into future copulations, instead of increasing the rapist's short term fitness through impregnation, is mentioned several times in the volume. However, these discussions stop frustratingly short of an actual systematic evaluation of the evidence that would test it. For example, Knott states that the rarity with which orangutan forced copulations result in serious wounds suggests that it may be a short-term reproductive strategy in this species. She then states that human forced copulations are likely to be a long-term reproductive strategy because the high frequency with which human forced copulations results in serious injuries is in “stark contrast” to the orangutan data (p. 103). She then presents abundant evidence about the rarity of serious injury in orangutans, but provides no evidence as to the frequency of serious wounds resulting from human forced copulations. This is made all the more frustrating when Thompson later makes a statement that appears even to go directly against the claim that the evidence on injuries among humans is in “stark contrast” to the orangutan evidence. Thompson states that even when stranger rapes are included in the category of human forced copulations, “statistics suggest that severe injury to victims is actually quite rare.” (p. 363). Although I continue to reject the hypothesis that any forms of human rape are “long-term” adaptations, for the reasons stated in Thornhill and Palmer (2000, pp. 58–59), this is certainly a hypothesis worthy of serious systematic testing and doing so would have made this fine volume even stronger. I would also add that if such tests are focused on the dichotomy between “stranger rapes” and “acquaintance rapes,” they should seriously question whether or not those categories would have been salient in the evolutionary past to the extent they are today.
Thompson's chapter explicitly on human rape is particularly disappointing. Instead of systematically testing new hypotheses, it is mainly a muddled and incomplete review of earlier evolutionary explanations of rape. For example, I am credited with somehow simultaneously arguing for both the by-product explanation of human rape (pp. 348, 367) and the hypothesis that human rape “is a short-term mating strategy” (p. 362; see also pp. 358, 367). This mistake appears to result from both an inaccurate portrayal of what is actually written in Thornhill and Palmer (2000) and a lack of awareness that I have repeatedly argued that the age distribution of rape victims does not necessarily support the rape as adaptation hypothesis for reasons very similar to the reasons Thompson provides (for a clarification of my positions on the rape as adaptation hypothesis, see Palmer 1991; 1992a; 1992b.) As to the unsupported assertion that evidence supporting the by-product explanation of rape “will inevitably fit equally well with exclusively sociocultural explanations of rape” (p. 348), I am simply dumbfounded. This statement would seem to imply that sociocultural explanations of rape are not only in agreement with the claim that rapists are motivated by sexual desire, but also that “compared to females, males have evolved increased susceptibility to visual arousal, higher sex drive, greater desire for sexual variety, and more willingness to engage in casual sex, …” (p. 348). I would like to believe such agreement exists, but am skeptical that this is the case.
Unfortunately, the greatest lack of clarity is found in the discussion of the topic with the single greatest practical significance: the motivation of rapists. Thompson first clearly states her own position “Other arguments, too numerous and varied than I can give justice to in this forum, suggest that rape at its root is not a sexual behavior but part of a culturally mediated pattern of male patriarchy and subjugation of women” (p. 350; emphasis added). She follows this with an equally clear statement about the origin of her own position: “The influence of feminist scholar Susan Brownmiller (1975) has been particularly strong in developing the argument that rape is ultimately a crime of violence and power rather than one of sexual desire.” (p. 350); emphasis added). Then, however, things become much less clear when she writes (p. 350): “Although Brownmiller has been held up as a straw-woman by proponents of the evolutionary hypotheses, her writing reveals neither ignorance nor denial of biological influences on human sexuality. … Brownmiller's and most feminist perspectives pose not that rape has no relation to sex, but that sex is secondary to violence and degradation as motivators for rape.” If this last sentence is what Brownmiller and other feminists really said (and this is a very large “if”, see Palmer and Thornhill 2003a; 2003b), then wouldn't Thompson's earlier statement (p. 350) that “Brownmiller developed the argument that rape is ultimately a crime of violence and power rather than one of sexual desire” be a prime example of misportraying Brownmiller's position? The only thing really clear from these sentences is that a question with such large practical significance deserves discussion that doesn't hinge on undefined terms like “at its root,” “ultimately,” and “secondary.”
I hope this book can be used to start such a discussion, not just on the specific motivation of rapists, but on more general questions such as the relationship between evolutionary biology and traditional social science disciplines like cultural anthropology. For example, Rodseth and Novak state that “We do not see the system [i.e., society] as an autonomous or ultimate source of human behavior (nor, by the way, do most cultural anthropologists these days—a point that has been slow to dawn on many evolutionists still tilting at cultural determinism)” (p. 312). The death of cultural determinism would be important news indeed, and a cultural anthropology class discussing the causes of rape would be an ideal context in which to test the hypothesis that it is now safe to put away one's jousting lance.
Finally, it should be mentioned that: “There are no less than 22 women scientists as authors in the volume, two-thirds of the total number of authors, with nine being either sole or primary authors of articles.”(Jane Lancaster, back cover). Hopefully no one persuaded to read this book for these reasons will notice that there are no fewer than two male scientists as its editors, 100% of the total number of editors. All joking aside, my serious hope is that there will soon come a time when hypotheses about human behavior will be evaluated solely on their correspondence with the real world, instead of the characteristics of those putting forth the hypotheses. This book, for example, is worthy of being read regardless of the gender of the authors who wrote it.