A Darwinian interpretation of individual differences in male propensity for sexual aggression

A DARWINIAN INTERPRETATION OF INDIVIDUAL DIFFERENCES IN MALE PROPENSITY FOR SEXUAL AGGRESSION Author(s): Martin L. Lalumière and Vernon L. Quinsey Source: Jurimetrics, Vol. 39, No. 2 (WINTER 1999), pp. 201-216 Published by: American Bar Association Stable URL: http://www.jstor.org/stable/29762599 Accessed: 31-03-2015 02:28 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. American Bar Association is collaborating with JSTOR to digitize, preserve and extend access to Jurimetrics. http://www.jstor.org This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A DARWINIAN INTERPRETATION OF INDIVIDUAL DIFFERENCES INMALE PROPENSITY FOR SEXUAL AGGRESSION Martin L. Lalumiere Vernon ABSTRACT: for sexual Darwinian L. Quinsey* This article reviews studiesof individualdifferencesinmale propensity for the formulation the implications of the findings of examines aggression, and discusses for law and policy. theories of sexual aggression, implications A Darwinian view of sexual aggression is likelyto have practical implicationsthrough betterunderstandingof itsetiology. Martin CITATION: L. Lalumiere and Vernon L. Quinsey, A Darwinian Interpretation of IndividualDifferences inMale Propensity for Sexual Aggression, 39 Jurimetrics J. 201-216(1999). I. INDIVIDUAL DIFFERENCES Any theory aimed at explaining male sexual aggression must incorporate what is known about individual differences inmale propensity for sexually aggressive behavior. These individual differences can be grouped, for themost part, according to threemajor factors: deviant sexual preferences, mating effort, and antisociality. In this article we define these terms, review the empirical *Martin L. isAssistant Professor of Psychiatry and Criminology, Lalumiere, Ph.D., C.Psych., University of Toronto, and Research Psychologist, Forensic Division, Center for Addiction and Mental Health. Vernon L. Quinsey, Ph.D., C.Psych., is Professor of Psychology and Psychiatry, Queen's University atKingston. Dr. Michael Seto provided very useful suggestions on an earlier draft of this article. WINTER 1999 201 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey We then discuss implications for evidence, and offerDarwinian interpretations. on men We focus who are sexually aggressive against law and public policy. men to refer who women, but also occasionally sexually offend against children. We discuss both acquaintance and stranger rape, but due to space limitationwe will not discuss marital rape or rape thatoccurs in the context ofwar and social upheaval.1 A. Deviant Sexual Preferences Sexual preferences are usually considered deviant when they are both (1) statistically unusual and (2) likely to inflictunwanted harm on self or others if acted upon. The deviant sexual preferencesmost often studied includepedophilia (a preference for prepubescent males or females) and preferential rape (a preference for violent, nonconsenting sexual activities with postpubescent individuals, most often females). Child molesters and rapists are the most commonly studied groups of sex offenders. From a Darwinian perspective, anomalous sexual preferences are those that lower one's inclusive fitness inmost circumstances (especially in the environ? ment inwhich our species evolved). Anomalous preferences encompass most, if not all, sexual deviancies, most major paraphilias as usually defined inpsychiatry or sexology, and other sexual preferences, such as homosexuality, that are not usually considered deviant or paraphilic. Anomalous sexual preferences aremuch more common inmen than inwomen. They have rarely been documented in nonhuman species, and, because they reduce rather than enhance reproductive success, they are relatively rare. Male sexual preferences can be measured ina number ofways.2 Phallometry, themeasurement of penile erection during the presentation of sexual stimuli in the laboratory, offers themost objective measure, even when men aremotivated to conceal their true preferences.3 The phallometric study of male sexual aggressors has produced very consistent findings. Men apprehended for rape, defined here as a sexual assault against a postpubescent female, show greater relative penile arousal to audiotaped stories depicting nonconsenting, coercive sex thanmen who have never been apprehended for a sexual offense.4One study homicide wilson, (1988); richard wrangham (1996) (offering a Darwinian view on these topics). 2. See Vernon L. Quinsey etal., The Phylogenetic and Ontogenetic Development of Sexual Age sex offender and Measurement inMales: Issues, in the juvenile Conceptual Preferences 143-63 (Howard e. Barbaree et al. eds.,1993). of sexual L. lalumiere, assessment & martin L. quinsey 3. See generally vernon & Dale 1. See generally martin Demonic Peterson, daly & margo Males Children Against (1996). 4. See Martin L. Lalumiere & Vernon L. Quinsey, The Discriminability ofRapistsfrom Non-Sex 150 (1994); 21 crim. just. & Behav. A Meta-Analysis, Offenders Using Phallometric Measures: with Rapists, Martin L. Lalumiere & Vernon L. Quinsey, The Sensitivity of Phallometric Measures Offenders 6 Annals Sex Res. 123 (1993) (providing quantitative reviews). 202 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences on self-reported sexual aggression (mostly acquaintance rape) among young males recruited from the community produced similar results.5Larger differences between phallometric measurements of rapists and othermen are foundwhen the audio stimuli include very graphic and brutal descriptions of rape scenarios.6 Child molesters' phallometrically measured sexual preferences differ from those of othermen (in thiscase, they exhibit preference for children over adults).7 Phallometrically measured sexual preferences have higher discriminant validity than any othermethod when the appropriate procedures are used.8 Phallometric measures are also good predictors of sexual recidivism among both rapists and childmolesters.9 of Individual Causes Differences in Sexual Preferences The male sexual preference system appears to directmen's sexual behaviors toward fertilewomen. Judgments of physical and sexual attractiveness, covertly measured viewing time, and phallometry indicate thatmost men, regardless of theirown age, prefer healthy, average weight, young adult females with specific waist-to-hip ratios as sexual partners.10 There is striking agreement across sexual cultures on the sexual attractiveness of individual women.11 Male success with female for characteristics associated reproductive preference appears to be an adaptation. Most men's sexual preferences are, similar to other 5. See Neil M. Malamuth, Predictors ofNaturalistic Sexual Aggression, 50 J. personality psych. 953 (1986). But see Martin L. Lalumiere & Vernon L. Quinsey, Sexual Deviance, & Antisociality, Mating Effort, and the Use of Sexually Coercive Behaviors, 21 personality & soc. 33 (1996) (failing to replicate findings). et al., Empathy for the Victim and Sexual Assault Among Rapists 435 (1994). violence Nonrapists, 9 J. interpersonal 7. Quinsey & Lalumiere, supra note 3. Individual Differences 6. See Mamie e. Rice and the Use of L. Lalumiere & Grant T. Harris, Common Questions Regarding J.res. & treatment 227 (1998). Testing with Sexual Offenders, 10 sexual abuse: and et al., violent appraising L. quinsey offenders: 9. See generally vernon in their Risk (1998). Follow-up studies indicate that child molesters are more specialized Managing offending than rapists in the sense that they are more likely to commit a new sexual offense and less 8. See Martin Phallometric in a particular type of likely to commit a subsequent nonsexual offense than rapists. Specialization offense, however, can be used in different senses. Rapists, with the exception of those who have already committed a number of rapes, are unspecial ized in the sense that their next crime ismore in the sense that they are more likely to be nonsexual than sexual. However, rapists are specialized likely to commit a new sex offense than offenders who have never committed one. 10. See generally Vernon L. Quinsey et al., Viewing Time as a Measure of Sexual Interest, 17 341 (1996); Douglas T. Kenrick & Richard C. Keefe, Age Preferences & sociobiology ethology inHuman Reproductive Strategies, 15 behav. & brain sci. 75 inMates Reflect Sex Differences (1992). 11. See generally Michael R. Cunningham et al., Their Ideas ofBeauty Are, on theWhole, the Same as Ours: Consistency and Variability inCross-Cultural Perception ofFemale Attractiveness, 261 (1995). & Soc. Psychol. 68 J.Personality WINTER 1999 203 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey aesthetic experiences, "unconsciously realized avenues to high fitness inhuman evolutionary history."12 Like other emotional, motivational, and perceptual systems, the sexual preference system is probably modularly organized, each "module" designed to guide behavior and to solve a particular problem of partner selection and Many of themodules, for example, those related to gender, age, body courtship.13 and partner variety, are sexually dimorphic in that themodules ofmales shape, and females differ on average.14 From a Darwinian point of view, anomalous sexual preferences that reduce fitness are likely to be caused by pathological processes.15We have hypothesized that different anomalous sexual preferences, such as homosexuality and pedophilia, are themanifestation of differentmalfunctioning modules, likely caused during the sexual differentiation of the male brain in utero. Male homosexuality would involve a malfunction of one of the "gender" modules, while themodules (preference foryouth, partner variety, and so on) remain intact. Male pedophilia would involve amalfunction of the"body shape" module, while the other modules, such as preference for youth, would remain intact.Other malfunctions of various modules associated with phases ofmale courtship could lead to exhibitionism, voyeurism, toucheurism, or preferential rape.16 One possible cause ofmodule malfunction is a maternal immune response tomale-specific features of the fetus, such as circulating testosterone or other androgens, H-Y or othermale-specific antigens, or other paternal antigens.17This immune response may lead to incomplete or disrupted masculinization of what of evolutionary psychology 12. Randy Thornhill, Darwinian Aesthetics, inhandbook (Charles Crawford & Dennis L. Krebs eds., 1998). on 13. See generally Vernon L. Quinsey & Martin L. Lalumiere, Evolutionary Perspectives J.Res. & treatment 301 (1995); Martin L. Lalumiere et al., Abuse: Sexual Offending, 7 Sexual J.RES. Sexual Deviance and Number ofOlder Brothers AmongSexual Offenders, 10 sexual abuse: 543-72 (offering more on themodular view of sexual preferences); John Tooby & & Evolutionary Psychology and theGeneration of Culture, Part 1, 10 ethology 29 (1989) (offering more on themodular view of the human psyche). 14. There is also strong evidence that one proximal cause of male sexual preferences involves the organizational effects of testosterone on themale fetal brain. See generally Lee Ellis & M. Ashley & Treatment Leda Cosmides, Sociobiology 5 (1998) A Theory of Homosexuality and Sexual Orientation: Ames, Neurohormonal Functioning bull. 101 psychol. 233 (1987); Arthur P. Arnold, Sexual Differentiation on the Heterosexuality, Zebra Finch Song System: Positive Evidence, Negative Evidence, Null Hypotheses, and a Paradigm L. Collaer & 572 (1997) (exploring sexual differentiation); Marcia Shift, 33 J.neurobiology Hines, Human Behavioral Sex Differences: A Role for Gonadal Hormones During Early bull. 118 psychol. 55 (1995). Development?, is defined as a failure of a mechanism to perform its evolved function. 15. Pathology 16. See generally Kurt Freund, Courtship Disorder: Is This Hypothesis Valid?, 528 ANNALS N.Y. ACAD. SCI. 172(1988). inMen, 17. See generally Ray Blanchard & Philip Klassen, H-Y Antigen and Homosexuality Melissa 185 J. Theoretical Biology 373 (1997) (presenting H-Y as themost 204 likely candidate). 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences is originally a female brain.18One possible cause of amaternal immune response inuteromay be successive pregnancies with male fetuses.19 Much remains to be learned about the pathological causes of anomalous sexual preferences. A cross-fostering design is needed to determine whether anomalous preferences are developed prenatally or otherwise.20Although current postnatal theories of the development of sexual preferences do not predict the observed sibship composition of homosexual men and paraphilic sex offenders, thepossibility that the "older brother effect" reflectspostnatal influences cannot be totally excluded. Assuming that a prenatal maternal immunoreactivity is shown, the operative maternal antibodies and their genetic mechanism have to be identified.One clue may be that homosexuality is will templates heritable.21 It is possible that the genetic marker on the long arm of the X chromosome associated with male (but not female) homosexuality22 is related to genes involved in immunoreactivity. Finally, the evolutionary mechanism that are more in brain the "default" because 18. Males likely to experience malfunctions is female. See sources cited supra note 14. development 19. See generally Thomas Gualtieri & Robert E. Hicks, An Immunoreactive Theory ofSelective Male Affliction, 8 behav. & brain Sei. 427 (1985). The idea that a maternal immune response can disrupt the development of themale sexual preference system is supported by the following evidence: (1) homosexual males, paraphilic rapists, and paraphilic child molesters tend to be born late among their brothers but not among their sisters; and (2) homosexual males show female-like or less masculinized hypothalamic and commissural brain structures, body development (weight and onset abilities, fingerprint patterns (which are determined in utero), and auditory interhemispheric laterality. See generally Ray Blanchard, Birth Order and Sibling Sex Ratio in 8 Ann. Rev. Sex Res. 27 (1997) (reviewing Homosexual Versus Heterosexual Males and Females, the extensive evidence concerning birth order and male homosexuality). See Karine Cote et al., Birth of puberty), spatial Sexual Preferences Among Sexual Offenders (Nov. 1998) Birth Interval, and Deviant (unpublished manuscript); Lalumiere et al., supra note 13 (reviewing evidence regarding the birth order of paraphilic sex offenders). For more findings on subgroups of sex offenders, see Anthony F. psychol. 331 Bogaert et al., Pedophilia, Sexual Orientation, and Birth Order, 106 J.abnormal (1997); JiriRaboch & Jan Raboch, Number of Siblings and Birth Order of Sexually Dysfunctional 12 J. SEX & marital 73 (1986); Ray Blanchard & therapy Males and Sexual Delinquents, Order, Sex Offenders Against Versus Heterosexual Anthony F. Bogaert, Birth Order inHomosexual behav. 595-603 (1998); Lalumiere etal., sexual Children, Pubescents, and Adults, 27 archives supra note 13. One would expect that pedophilic child molesters, who do not have themale-typical preference for small waist-to-hip ratios, would show similar "feminized" characteristics. Whether preferential rapists,who seem to have a hyper-male desire for dominance and aggression, would show is unclear. To date, no one has been able to identify naturally the same feminized characteristics occurring psychosocial, postnatal sources of variation in sexual preferences. 20. See Martin L. Lalumiere & Vernon L. Quinsey, Pavlovian Conditioning of Sexual Interests 241 (1998) (reviewing classical conditioning). Of inHuman Males, behav. 27 archives sexual course, this does not mean that carefully engineered environments could not alter the development of sexual preferences. See generally Blanchard, supra (reviewing postnatal theories of birth order effects on the development of sexual preferences). 21. See Richard C. Pillard & J.Michael Bailey, Human Sexual Orientation Has a Heritable 347 (1998). Component, 70 hum. biology 22. Dean H. Hamer et al., A Linkage Between DNA Markers on theX Chromosome and Male 261 science 321-27 (1993); Stella Hu et al., Linkage Between Sexual Sexual Orientation, 248-56 11nature inMales genetics but Not inFemales, Orientation andXq28 (1995). WINTER 1999 205 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey maintains anomalous sexual preferences in thepopulation despite theirnegative effects on Darwinian fitnesswill have to be specified.23 Defining anomalous sexual preferences as fitness reducing and viewing the sexual preference system as modular and designed to solve particular problems of partner selection and courtship offer strong theoretical guidance to research on the causes of variation inmale sexual preferences. This research is important because anomalous sexual preferences are known to be crucial factors in predatory rape and childmolestation. Of course, not all sex offenders are sexually deviant; some acts of rape seem to be part of a sexual strategy requiring a high amount ofmating effort. B. Mating Effort Men exhibit more interest thanwomen in partner novelty, casual sex, and physical attractiveness.24This may be part of a male-preferred courtship-mating strategy associated with male preference for physical signs of female reproduc? tive capability. Differences in thepreferred dating and mating strategies ofmen and women are expected from differences between the sexes in theminimum amount of parental investment required for successful reproduction. In ancestral environments, number of sexual partnerswas likely to have been an important factor limiting reproductive success among men, while the amount of paternal investmentwas an important limiting factor among women. A Darwinian view of heterosexual relationships suggests thatmen and women both compete and compromise with each otherbecause theirreproductive interestsare not identical. One way inwhich the divergent reproductive interests ofmen and women are manifested ismale sexual coercion. Such coercion, by definition, circumvents female choice. There are a number of conditions inwhich men might be expected to be sexually coercive: when the costs of such coercion are low (as, for example, in wartime25), when women are perceived as political or ideological adversaries,26 when men are unable to calculate or perceive possible costs (because of alcohol 23. We suspect that this process is a byproduct of health benefits derived from having highly responsive immune systems. 24. See generally David M. Buss, Sex Differences Tested in 37 Cultures, 12 behav. & brain Hypotheses inHuman Mate Preferences: Evolutionary 1 (1989); David M. Buss & David p. 100 psychol. Schmitt, Sexual Strategies Theory: An Evolutionary Perspective on Human Mating, REV. 204 (1993); Russell D. Clark III, The Impact of AIDS on Gender Differences inWillingness to inCasual Sex, 20 J.applied 771 (1990); Russell D. Clark III & e. Hatfield, soc. psychol. Engage sci. 39 (1989); inReceptivity to Sexual Offers, 2 J. psychol. & HUM. sexuality Variations inHuman Mating Tactics: An et al., Sex Differences andIntra-Sex 3 (1995). & sociobiology 16 ethology Evolutionary Approach, II of World War The Forgotten Holocaust 25. See Iris Chang, The Rape of Nanking: Gender Differences a. Landolt Monica (1997). 26. See William & soc. psychol. D. Walker et al., Authoritarianism and Sexual Aggression, 65 j. personality 1036 (1993). 206 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences in dating situations,27 or because they exhibit antisocial induced myopia men can attractmany partners and are unconcerned about and when tendencies,28 their future relationship with a particular woman.29 Mating effortisdefined as energy directed to locating, courting, and sexually interactingwith members of the preferred sex and age. It can be contrasted with parenting effort,inwhich energy is directed to protecting and investing in one's mate and offspring.Mating and parenting effortcan be seen as opposite ends of a continuum of energy distribution in a given time period. Some kind ofmating effortmust precede parenting effort,butmating effort isnot always followed by parenting effort.Men expend more mating effort than women, but there are notable male intrasexvariations.30These variations are associated with personal characteristics and behaviors, such as antisociality and a history of sexually coercive behavior in dating contexts. Mating effortcan be measured ina number ofways. In our researchwe have used two self-reportmeasures: the Sociosexuality Inventory31(SOI), a seven-item questionnaire that combines both interestand success inmating effort,and the PartnerVariety and Casual Sex scale32 (PVCS), an eleven-item questionnaire that measures interest in attracting and acquiring short-term sexual partners. Questions about sexual history (for example, age at first intercourse,number of lifetime sex partners, number of one-night stands in the lastyear) have also been used to assess male intrasex variation inmating effort. Two recent studies on thedating interestsand behaviors ofmen showed that men who are interested inand successful inpursuing a highmating effortstrategy tend to reporthaving been sexually coercive in the past. Men who score high on measures of mating effort also report higher sensation seeking, higher anti sociality, and more adversarial sexual beliefs (e.g., "In a dating relationship a woman is largely out to take advantage of a man"), compared tomen who score Other researchers have found that sexually coercive men low on mating effort.33 an extensive history of uncommitted sexual relationships, a preference for have 27. See generally Mary p. Koss & John A. Gaines, The Prediction of Sexual Aggression violence Use, Athletic Participation, and Fraternity Affiliation, 8 j. interpersonal in Sexual Aggression, C. Seto & Howard e. Barbaree, The Role of Alcohol (1993); Michael Rev. 545 (1995). Psychol. Clinical Alcohol by 94 15 28. See infra text accompanying notes 46-49. 29. Lalumiere & Quinsey, supra note 5. 30. See generally David C Rowe et al., Mating or A Conditional Effort in Adolescence: differences 105 (1997). & individual Alternative Strategy, 23 personality in Individual Differences 31. See generally JeffreyA. Simpson & Steven W. Gangestad, & soc. Evidence for Convergent and Discriminant Validity, 60 j. personality Sociosexuality: psychol. 870 (1991). 32. Lalumiere & Quinsey, supra note 5. 33. See generally Martin L. Lalumiere et al., A Test of theMate Deprivation Hypothesis of 299 (1996); Lalumiere & Quinsey, supra note 5. 17 ethology & sociobiology Sexual Coercion, WINTER 1999 207 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey partner variety and uncommitted sex, and hostile and antisocial tendencies.34 Although this research was conducted mainly with students or other individuals who have predominantly reported engaging in acquaintance rape, preliminary findings from our research using adjudicated rapists (who typically have committed stranger rapes) suggest that thesemen also score high on measures of mating effort. Causes of Variation inMating-Parenting Effort Elsewhere we have argued that the male sexual psychology has been designed tomaximize reproductive success by varying the ratio of mating to parenting effort according to the following circumstances:35 one's own mate value, which is itselfdetermined by factors such as attractiveness, personality, social status, access to resources; the target'smate value, which is related to the probability of successful interactionwith a particular person; the local sex ratio (that is, availability of potential partners relative to the number of competitors); and current social conditions and norms.We have found that students' choice of mating tactics are related to theirperception of theirmating success and to the physical attractiveness of the target person. Men who perceive themselves as more successful inattractingpartners tend to adopt a short-term mating approach, and physically attractive female targets tend to elicit a long-termmating approach inmen. Almost all men who perceived themselves as less successful chose long termmating tacticswhen exposed to a very attractive female.36 Ethnographic evidence suggests thatmen who succeed in competition for resources or status tend to increase their number of mates and have greater reproductive success.37 Cross-cultural research shows thatwomen prefermates who have such characteristics as good financial prospects, ambition, and industriousness.38 In a recent study, Perusse found that unmarried males who scored high on measures of income, prestige, and power also scored high on a measure combining number of sexual partners and frequency of intercourse.39 Success in competition for resources or status, or both, is likely an important variable affecting mating success and, consequently, an important variable affectingmales' position along themating-parenting effortcontinuum. et al., Predicting Men's Antisocial Behavior Against Women: The 34. E.g., Neil M. Malamuth issues inetiology, Interaction Model ofSexual Aggression, insexual aggression: assessment, and treatment 63 (G.C.N. Hall et al. eds., 1993); David B. Sarwer et al., Sexual Aggression and behav. sexual 265 (1993). Love Styles: An Exploratory Study, 22 archives Sexual Strategy, 35. See generally Michael C. Seto et al., Sensation Seeking and Males' Differences 669 (1995); Quinsey & Lalumiere, supra note 13. Personality & Individual 36. Landolt et al., supra note 24. 19 in Industrial Societies: inDaniel Perusse, Cultural and Reproductive Success 37. Reviewed Testing theRelationship at theProximate and Ultimate Levels, 16 behav. & brain sci. 267 (1993). 38. Buss, supra note 24. 39. Perusse, supra note 37. 208 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences The relationships between competition for resources and status,mating effort,mating success, and the use of sexually coercive tactics have been discussed as part of the resource deprivation hypothesis. This hypothesis states that (a) men compete more thanwomen for status and resources, (b) men who gain more resources and status enjoy reproductive benefits because women prefer tomate with successful men, (c) men who are less successful at gaining resources and statushave reduced access to desirable women and turnto alternativemating strategies such as sexual coercion. According to this hypothesis, rape is part of the evolved mating strategybut is not a predominant mating tactic.40 The idea that rape may be part of an evolved, adaptive mating strategyhas received some support. Unlike other criminals, rapists tend to select victims of reproductive age,41 and men who repeatedly commit sexual offenses are increasingly likely tohave intercoursewith theirvictims.42 In turn,rapemay have exerted selection pressure on women's psychology and behavior. For example, married rape victims of reproductive age have more profound emotional and behavioral responses to rape than other females,43 and fertile (ovulating) females are more likely to avoid situations where a threat of rape may exist than other females.44 As predicted by the resource deprivation hypothesis, convicted rapists tend to come from lower social strata. However, studies assessing the direct relationship between mating success and theuse of sexually coercive tactics have not supported the hypothesis. As mentioned above, young males who perceive themselves as less successful tend to adopt a long-termmating strategy (showing a compromise with females' preferences) and do not reporthaving used sexually coercive tactics, whereas young males who perceive themselves as more successful tend to adopt a short-termmating strategy (high mating effort) and more frequently reporthaving used sexually coercive tactics.Also, men who have good earning potential have been shown to use sexually coercive tactics and high mating effort strategies, butmore research is needed on this issue. 40. See generally Lalumiere et al., supra note 33; Randy Thornhill & Nancy W. Thornhill, 137 (1983); Randy & sociobiology Analysis, 4 ethology Rape: An Evolutionary Thornhill & Nancy W. Thornhill, The Evolutionary Psychology ofMen's Coercive Sexuality, 15 Behav. & Brain Sci. 363 (1992). 41. See generally Richard B. Felson & Marvin Krohn, Motives for Rape, 27 J.Res. Crime & 222 (1990); other evidence reviewed inThornhill & Thornhill, supra note 40. Delinquency Human 42. See generally W.D. Walker, Patterns in Sexual Offending (1997) (unpublished doctoral dissertation on file with Queen's University, Kingston). in Victims inNancy W. Thornhill, Psychological Adaptation toSexual Coercion 43. Reviewed and Feminist Perspectives Evolutionary and Offenders, in Sex, Power, and Conflict: (David M. Buss & Neil M. Malamuth eds., 1996). 44. See generally Tara J. Chavanne & Gordon G. Gallup, Variation inRisk Taking Behavior & Hum. Among Female College Students as a Function of theMenstrual Cycle, 19 evolution 27 (1998). That male sexual coercion may have been a strong selection pressure on females Behav. in Animal in T.H. Clutton-Brock & G.A. Parker, Sexual Coercion inmany species is discussed Societies, 49 animal WINTER behav. 1345 (1995). 1999209 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey In summary, high mating effortand high mating success are characteristics of young, unadjudicated, sexually coercive men. Studies of adjudicated rapists (who typically have committed predatory rapes), ofmen of low socio-economic statusand poor prospects, and of older men are needed to furthertest the resource deprivation hypothesis. The idea that sexually coercive tactics are part of an evolved mating strategy (whether universal or not) is likely to be correct, but the actual parameters of the strategy, including the identificationof the contexts that aremore likely to elicit theuse of coercive sex, need to be elucidated. It is clear, however, thata preference forhighmating effortand theuse of sexually coercive tactics are closely linked. Furthermore, both mating effortand coercive sex are closely linked to antisociality. C. Antisociality Antisociality is a construct describing behaviors, attitudes, beliefs, personality features, and interpersonal styles thatare generally harmful to others. Antisocial individuals have early, varied, and chronic conduct "problems." They are usually aggressive, hostile, impulsive,manipulative, and callous. Psychopathy is the extreme manifestation of antisociality.45 Sexually coercive men have antisocial personality characteristics such as lack of empathy, domineeringness, hypermasculinity, and hostility.46Sex offenders, particularly rapists, tend to engage in other antisocial acts and tend to have a history of juvenile delinquency.47 Adjudicated rapists and child molesters do not differ from other offenders on antisocial characteristics,48but antisociality is one indicators are highly heritable. E.g., Donna R. Miles & Gregory Carey, Genetic 45. Antisociality 207 & Soc. psychol. and Environmental Architecture ofHuman Aggression, 72 J. personality (1997) (discussing twin and adoption studies on aggression, psychopathy, and socialization). 46. See generally M.p. Koss & T.E. Dinero, Predictors ofSexual Aggression Among a National sci. 133 (1988); David S. Kosson et al., N. Y. acad. Sample ofMale College Students, 528 annals 12 J. Traits Predict Self-Reported Sexual Aggression Among College Men, Psychopathy-Related et al., Rape: The Roles of Outcome Violence 241 (1997); William O'Donohue Interpersonal 8 sexual abuse: and Hypermasculinity, Expectancies et al., Sexual Coercion and Sexual Assault: Male Mahoney coercion J.res. & treatment Socialization and Female 133 (1996); E.R. Risk, 1 sexual 2 (1986); Neil M. Malamuth & Nancy W. Thornhill, Hostile Masculinity, & assault behav. inConversations, 20 aggressive Sexual Aggression, and Gender-Biased Domineeringness 185 (1994); Marnie E. Rice et al., Empathy for the Victim and Sexual Assaults Among Rapists and Violence 435 (1994); Michael C. Seto & H.E. Barbaree, Victim 10 J. Interpersonal Nonrapists, 167 sex res. Blame and Sexual Arousal to Rape Cues in Rapists and Nonoffenders, 6 annals (1993). 47. See generally K.S. Calhoun et al., Sexual Coercion and Attraction to Sexual Aggression violence 392 (1997); Neil M. 12 J. interpersonal in a Community Sample of Young Men, a a National et al., Characteristics Malamuth of Aggressors Against Women: Testing Model Using psychol. 670 (1991); Delbert S. Elliott, & Clinical Sample ofCollege Students, 59 J.consulting Serious Violent Offenders: Onset, Developmental Course, and Termination-The American Society 1 (1994). criminology 32 Presidential 1993 Address, Criminology of 48. E.g., Vernon L. Quinsey et al.,MMPI Profiles ofMen Referredfor a Pretrial Psychiatric psychol. 410 (1980). Assessment as a Function of Offense Type, 35 J.clinical 210 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences of the best predictors of future sexual aggression among identified sex offenders.49 Juvenile and adult delinquents tend tohave a sexual history characterized by effort.50 Although more research is needed, mating effortand anti mating high sociality appear to be intimately linked, and perhaps represent two aspects of the same phenomenon.51 Antisocial characteristics are probably necessary to a high mating effort strategy,because this strategy requires thatmales not compromise with females' preferences and often results in harm to others. Conversely, an with parental antisocial strategy to achieve fitness-relevant goals likely interferes effort.Thus, the search for the origin of individual differences in antisociality will likelyprovide clues in the search for theorigins of variation inmating effort and the use of sexually coercive tactics. of Variations Causes inAntisociality Mealey, Rowe, and Vila,52 among others, have offered cogent and testable Darwinian hypotheses on the causes of variation inantisociality. Both conditional and alternative strategy53models have been proposed, and thus far the latter model has received greater empirical support.Here we focus on thevariations in an extreme pattern of antisociality and mating effort,psychopathy. Psychopathic offenders are impulsive, deceitful, selfish, and irresponsible individuals who have very littleremorse or guilt for theirmisbehaviors and little concern for thewelfare of others.54Compared to nonpsychopathic offenders, psychopathic offenders have more extensive criminal histories, are more prone to instrumental rather than emotionally laden reactive violence, are more likely touse weapons, aremore likely to select strangers as victims, and aremore likely to cause serious injury to theirvictims. They respond differently to institutional & M.T. Bussiere, Predicting Relapse: A Meta-analysis of Sexual Offender 348 (1998) (quantitative review). & Clinical psychol. Studies, 66 J.consulting and Drug Use As Risk 50. See generally Delbert S. Elliott & Barbara J.Morse, Delinquency inTeenage Sexual Activity, 21 youth & Soc'y 32 (1989); Daniel J.Flannery et al., Impact Factors 49. R.K. Hanson Recidivism 8 J. and Delinquency, Status, Timing, and Age on Adolescent Sexual Experience RES. 21 (1993); Rowe et al., supra note 30. See also Lee Ellis, Relationships of of Sub-Optimal Criminality and Psychopathy with Eight Other Apparent Behavioral Manifestations 905 (1987). differences & individual Arousal, 8 personality A Sibling 51. See generally David C. Rowe et al., Sexual Behavior and Nonsexual Deviance: of Pubertal adolescent 61 (1989); Rowe et al., supra note 30. Study of Their Relationship, 25 dev. psychol. 52. See generally Linda Mealey, The Sociobiology ofSociopathy: An Integrated Evolutionary & brain sci. 523 (1995); D.C. Rowe, An Adaptive Theory of Crime and 18 behav. Model, 268 (J.D. Hawkins ed., 1996); Rowe and crime: current indelinquency theories Delinquency, et al., supra note 30; Bryan Vila, A General Paradigm for Understanding Criminal Behavior: 311, 328-30 (1994). Theory, 32 criminology Extending Evolutionary Ecological 53. In conditional strategies the development of antisocial itydepends on specific environmental cues. In alternative strategies the development of antisociality depends on genetically based individual differences. 54. Robert WINTER D. Hare, The Revised Psychopathy Checklist (1991). 1999 211 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey treatment,and aremuch more likely to violate theirparole or commit new crimes once they are released from an institution.They are especially more likely to commit new violent crimes.55 Psychopaths also differ fromnonpsychopaths on behavioral, physiological, and neuropsychological measures. For example, psychopaths are less likely than other offenders to delay gratification in computerized learning tasks and they are more likely to persevere in a task despite punishment. Psychopaths process emotional informationdifferentlythannonpsychopaths. They are less reactive to cues of distress or fear, and to aversive stimuli like loud sounds.56 Recent research in our laboratory suggests thatpsychopathy may not be a psychiatric disorder. Compared to nonpsychopathic offenders, psychopathic offenders do not show the signs of developmental instabilitygenerally associated with psychiatric (and other) disorders. For example, in one studywe found that fewer difficulties occurred in the pregnancies and deliveries of children who became psychopathic offenders than of children who became nonpsychopathic offenders; in addition, psychopathic offenders scored lower on an index of morphological fluctuating asymmetry (perhaps thebest indicatorof developmen? tal instability) thannonpsychopathic offenders. Psychopathic offenderswere just in Instrumental and Reactive Violent 55. See generally D.G. Cornell et al., Psychopathy W. Jutai, & clinical Psychol. 388 (1996); Robert D. Hare & Jeffrey Offenders, 64 J.consulting inProspective Studies of Crime and Delinquency Criminal History of theMale Psychopath, eds., 1983); Robert D. Hare & 225,228-29 ({Catherine Teilmann Van Dusen & Sarnoff A. Mednick 7 Int'l J.L. & Violent and Aggressive Behavior by Criminal Psychopaths, Leslie M. McPherson, 15 L. & 35, 37 (1984); Grant T. Harris et al., Psychopathy and Violent Recidivism, 223 (1991); Marnie E. Rice et al., An Evaluation of a Maximum Security Therapeutic 399 Community for Psychopaths and Other Mentally Disordered Offenders, 16 L. & hum. behav. 207 inCriminal Psychopaths, 20 L. & hum. Behav. (1992); Ralph C. Serin, Violent Recidivism psychiatry hum. behav. in a Criminal of Psychopathy and Release Outcome (1996); Ralph C. Serin et al., Predictors 419 (1990); Michael C. Seto & H.E. Barbaree, Treatment Assessment 2 J. psychol. Population, et al., Sherrie Williamson and Sex Offender Recidivism Behavior (unpublished manuscript); J.behav. sci. 454 (1987). Violence: Criminal Psychopaths and Their Victims, 19 canadian 56. See generally Robert D. Hare, Performance ofPsychopaths on Cognitive Tasks Related to 133 (1984); Stephen D. Hart et al., Performance psychol. psychol. 374 Tests, 99 J.abnormal Neuropsychological et al., Altering a Dominant Response: Performance of Psychopaths and psychol. Low-Socialization College Students on a Cued Reaction Time Task, 102 J.abnormal 379 (1993); J. Intrator et al., A Brain Imaging (Single Photon Emission Computerized Tomography) Frontal Lobe Function, of Criminal Psychopaths (1990); Eric W. Howland 93 J.abnormal on Selected psychiatry inPsychopaths, 42 biological 96 (1997); Study ofSemantic and Affective Processing inPsychopathic and Nonpsychopathic et al., Delay of Gratification Offenders, Joseph P. Newman and 630 (1992); James R.P. Ogloff & Stephen Wong, Electrodermal psychol. 101 J.abnormal 17 crim. Just. & Behav. in Psychopaths, Evidence Cardiovascular 231, of Coping Response 241-43 J. Patrick et al., Emotion in the Criminal Psychopath: Fear Image et al., Abnormal psychol. 523, 528-29 (1994); Sherrie Williamson res. 260 (1991). of Affective Words by Psychopaths, 28 J.psychophysiology (1990); Christopher 103 J.Abnormal Processing, Processing 212 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences as symmetrical as nonoffenders.57Thus, the causes of psychopathy are unlikely to involve pathological neurodevelopmental processes. Taxometric analyses suggest thatpsychopaths are not at the high end of a continuum of antisocial characteristics but rather represent a naturally occurring class of individuals.58We and others have suggested that psychopathy is an adaptive life history strategy,59one that may have evolved by frequency dependent selection. Theoretically, psychopathy can be considered a lifehistory strategy consisting of high mating effort, an aggressive and risky ("warrior hawk") approach to achieving social dominance, and frequentuse of nonrecipro cating and duplicitous (cheating) tactics in social exchange.60 This approach leads to a specific hypothesis regarding sexual aggression. The high mating effortstrategy hypothesis states that (a) whereas somemen adopt amixture ofmating and parenting efforttactics according to circumstances, a small group of men adopt, as part of a generally antisocial lifestyle, a high mating effort strategy that relies on acquiring a large number of partners and invests very little inmates and offspring; (b) sexual coercion is only one of the tactics (along with charm, false promises, and deception) used by psychopaths to acquire multiple partners; (c) sexually coercive tactics are probably used when less coercive tactics are not successful with a particularwoman, orwhenever the costs of coercion are not too high. Thus, they use a high mating effort strategy due not to an inability to compete inprosocial ways for resources and status,but rather as part of an alternative strategy for social competition. We expect that these men are not more likely to have anomalous sexual preferences, such as sadism or preferential rape, thannonpsychopaths, butwe expect that theymight be more sexually responsive to a variety of sexual cues (including less conven? tional cues) and less inhibitedby women's cues of nonconsent.61 II. RAPE PREDICTION Two variables may predict predatory sexual aggression: psychopathy, as and a defined by instruments such as the Psychopathy Checklist-Revised, phallometrically measured preference for coercive and nonconsenting sex. The Roles of Psychopathy, 57. See generally Grant T. Harris et al., Criminal Violence: Insults, and Antisocial Parenting (unpublished manuscript); Martin L. Lalumiere Neurodevelopmental et al., Signs of Developmental Instability Among Violent Psychopaths (unpublished manuscript). 58. See generally Grant T. Harris et al., Psychopathy As a Taxon: Evidence That Psychopaths Are a Discrete 387 (1994). & clinical psychol. Class, 62 J.consulting 8 generally Henry C. Harpending & Jay Sobus, Sociopathy As an Adaptation, 63S (1987); Mealey, supra note 52; Vernon L. Quinsey, The Prediction & sociobiology ethology and Explanation 117, 124-26 (1995). of Criminal Violence, 18 Int'l J.L. & psychiatry 59. See 60. See generally R.I.M. Dunbar et al., Conflict and Cooperation Among the Vikings: 233 (1995); Lalumiere & 16 ethology & sociobiology Behavioral Decisions, and Sexual Strategy inPsychopathy, 22 Quinsey, supra note 5; Michael C. Seto et al., Deception Contingent Personality 61. We WINTER Differences 301 (1997). & Individual are currently researching these ideas. 1999 213 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey Rapists who are both psychopathic and sexually deviant are especially likely to commit new sexual offenses.62 The discovery of variables related to sexual offending and reoffending has allowed and guided the development of actuarial methods topredict rape and other violent acts.63Psychopathy and sexual deviance are part of a recently developed actuarial instrument for the prediction of recidivism among sex offenders.64 The Sex Offender Risk Appraisal Guide (SORAG) contains 14 variables,65 selected according to theirrelationship toviolent or sexual recidivism among sex offenders (both rapists and child molesters), and scored and combined to maximize predictive accuracy in samples other than those used to develop the instrument.Total scores, which can vary from -26 to+43, are linearly related to the likelihood of violent or sexual recidivism.66 The accuracy of the instrument is high enough that,with a very high cutoff, a small number of trulydangerous offenders can be identifiedwhile wrongly identifyingvery few or no offenders as dangerous. Unfortunately, minimizing the number of offenders incorrectly identified as dangerous means that some trulydangerous offenders are missed. However, the impressive predictive accuracy of theSORAG (and of theViolence Risk Appraisal Guide, an instrument to predict violent or sexual recidivism among offenders in general) has clear implications for law and policy. III. IMPLICATIONS FOR LAW AND POLICY theoretical and empirical endeavors can have practical, explanatory, or epistemological implications. Social and legal policies to enhance theprotection of the community from highly recidivistic sexual predators can be substantially aided by actuarial instrumentsthataccurately identifythe likelihood with which New 62. Marnie E. Rice & Grant T. Harris, Cross Validation and Extension of the Violence Risk 231, 236-38 (1997). Appraisal Guide for Child Molesters and Rapists, 21 L. & HUM. behav. et al., supra note 9 (discussing actuarial methods in the prediction of 63. See Quinsey violence and reviewing the history of prediction of violence and the development of accurate methods). 64. Hanson & Bussiere, supra note 49. In a recentmeta-analysis, variables pertaining to sexual deviance and antisocial lifestyle were the best predictors of sexual reoffending. Variables pertaining to psychological distress did not predict sexual reoffending. The predictive validity of variables indexing mating effort has not yet been investigated. Id. et al., supra note 65. See Quinsey scoring of the following variables, worded having lived with both biological parents of alcohol abuse, never married or never (discussing the details on the definition and according to their positive relationship to recidivism: not to age sixteen, elementary school maladjustment, history lived common law, criminal history score for violent and 9, at 241-45 nonviolent offenses based on the Cormier-Lang system, number of previous convictions for sexual offenses, history of sex offenses against people other than girls younger than fourteen, failure on prior conditional release, young age at index offense, diagnosis of personality disorder, no diagnosis of schizophrenia, and deviant results on phallometric tests). 66. For example, a score of -10 is associated with a 9% likelihood to reoffend violently over 10 years of opportunity; a score of+13 is associated with a 59% likelihood; and a score greater than +31 with a 100% likelihood. 214 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions A Darwinian Interpretation of Individual Differences an offender will commit a new sexual or violent offense. These instruments permit thebalancing of community safety and offenders' civil liberties thatform the basis of sensible legal and correctional strategies. Actuarial instruments enable policymakers to concentrate expensive supervisory and treatment resources on the highest risk offenders.67 Although theories may suggest predictors tobe included inactuarial instruments,the construction and evaluation of actuarial instruments are largely empirical engineering tasks rather than scientific, theoretical ones. Darwinian theories are likely to have longer range implications for social policy to the extent that they lead to the identification and explanation of specific etiological andmaintaining events. These may be environmental events thataffect development or current behavior of all men, or genes that cause individual differences among men. In either case, understanding proximal mechanisms is more important than understanding ultimate causes for designing policy interventions. Primary and secondary prevention of deviant sexual preferences such as pedophilia and preferential rapewill likelydepend onmodifying early etiological events in utero. Here, as with a variety of neurodevelopmental problems, social policies are needed to assist pregnantmothers. Prevention of antisocial behavior, at least for nonpsychopathic children, depends on parental skills and resources and on community and school-based programs,68 particularly for high risk children. Intensive effortswill be required tomodify thedevelopmental trajectory of psychopathic children. Turning to mating effort, a Darwinian view suggests that policies that facilitatemale parental investmentwill decrease sexual coercion. More generally, policies that increase the immediate costs ofmating effortand sexual coercion or decrease the opportunity to engage in them should result in a decrease in rape. Perhaps ironically, a central recommendation for crime reduction derived from sociological research69 is identical to that suggested by Darwinian thinking? namely, a policy designed to promote two-parent families and an increase in the number of caregivers relative to the number of children.70 The use of accurate factors to identifyhigh-risk individuals and the use of effective interventionandmanagement strategies to lower riskcannot be divorced of Criminal Conduct 67. Cf. D.A. Andrews & J.Bonta, The Psychology (1994). Intervention et al., The Effects of Early Educational 68. See, e.g., John R. Berrueta-Clement of delinquent inAdolescence and Early Adulthood, in prevention on Crime and Delinquency 220 (J.D. Burchard & S.N. Burchard eds., 1987); Dale l. Johnson & Todd Walker, Behavior inMexican-American Children, 15AM. J.community Primary Prevention of Behavior Problems Prevention As Cumulative psychol. 375, 382-83 (1987), reviewed by Hirokazu Yoshikawa, and Its Risks, Protection: Effects of Early Family Support and Education on Chronic Delinquency 28 (1994). Bull. 115 Psychol. Theory of & travis R. gottfredson 69. See generally michael HlRSCHI, A General Crime (1990). 70. Cf. E.E. Werner, Children WINTER of theGarden Island, Sei. Am., Apr. 1989, at 111. 1999 215 This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions Lalumiere and Quinsey from a number of legal and social policy issues, such as procedural fairness, informed consent, and availability of services. Theoretical work will help to identifypotential risk factors and interventions; legal and policy decisions will determine theiruse; and empirical and technological work will determine their efficacy. The epistemological influence of Darwinian thinking on legal and social policy is less direct but perhaps in the long runmore important.Dennett has called the idea of natural selection the "universal solvent" and "Darwin's dangerous idea" because it explains human nature in mechanistic terms.71 Although all causal scientific theories of human behavior are at least implicitly deterministic in the same way, the determinism seems to be more obvious in Darwinism. In a Darwinian context, organisms do not choose the characteristics they have. All human behavior has proximate causes thatwork because of a history of natural selection (the ultimate cause). In theDarwinian conceptual scheme, a person no more freely chooses a behavior than a snail chooses tohave no legs. a scientific determinist, then, the ideas of free will and criminal responsibility are unintelligible. Itwould make no sense topunish people because theywere "bad" or "deserve it,"although itmight make sense to punish them to To deter them fromdoing something similar again, deter others by example, prevent vigilante justice, or prevent them from doing something similar. Deterministic causal theories of crime encourage a utilitarian approach to legal and social policy at the expense of a moralistic one. 71. Meanings generally DC. of Life (1995). See dennett, darwin's dangerous 216 idea: evolution and the 39 JURIMETRICS This content downloaded from 137.122.64.71 on Tue, 31 Mar 2015 02:28:03 UTC All use subject to JSTOR Terms and Conditions