WILLINGNESS TO ENGAGE IN CASUAL SEX The Role of Parental Qualities and Perceived Risk of Aggression
M i c h e l e K. S u r b e y a n d C o l e t t e D. C o n o h a n
St. Thomas University
Sexually dimorphic mate selection strategies were examined in 200 university students reporting their willingness to engage in casual sexual encounters with hypothetical individuals of the opposite sex. Using a questionnaire format, the possibility of forming a long-term relationship was manipulated, while risk of disease, pregnancy, and detection was eliminated across all conditions. In addition, potential partners varied in level of attractiveness, and in personality and behavioral characteristics. As expected, men reported a greater anticipated willingness to engage in sexual intercourse across all conditions compared with women. The possibility of forming a long-term relationship elevated women's, but not men's, willingness for sexual intercourse. While a potential partner's attractiveness had a significant positive overall effect on responses, reducing their relative attractiveness had a greater negative impact on men's responses. Reference to the parental qualities of a potential partner significantly increased women's, but not men's, anticipated willingness for sexual intercourse. Describing a hypothetical partner as non-aggressive (safe) marginally increased women's willingness (p < .09) and did not affect men's responses. The wording of items relevant to this condition may have resulted in the potential partner sounding " w i m p y " rather than nonaggressive, and this may have reduced the expected effect of this manipulation. The possibility that w o m e n may trade off personality and behavioral characteristics with attractiveness to a greater degree than men when assessing potential mates is considered. Received: May 2, 1999; accepted July 23, 1999; revised version received May 7, 2000.
Address all correspondence to M. K. Surbey, School of Psychology, James Cook University, Townsville, QLD 4811, Australia. E-mail:
[email protected] Copyright 2000 by Walter de Gruyter, Inc., New York Human Nature, Vol. 11, No. 4, pp. 367-386. 367
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KEYWORDS" Female choice; Human mate selection; Parental qualities; Risk of physical aggression.
Differential selection pressures have presumably operated on m e n and women, resulting in the employment of sexually dimorphic mate selection strategies. Sex differences in mate choice apparently arose as a function of the initial disparity in parental investment (Bateman 1948; Trivers 1972). In species where minimum male investment in offspring is negligible compared with a female's investment in gestation and lactation, males have been selected to maximize copulations with fertile partners. Therefore, human male reproductive strategies should be biased toward the seeking of high numbers of partners displaying signs of fertility or high reproductive value. In contrast, w o m e n have been under greater selective pressures to choose mates capable of increasing the fitness of offspring by contributing either resources, parental care, or "good" genes (Trivers 1972) and, thus, should focus on these qualities in a potential mate. Considerable evidence exists for the employment of these sexually dimorphic reproductive strategies in extant h u m a n populations. Polygyny is more common than polyandry, married men tend to engage in extramarital affairs more often than their wives, and men express a desire for a greater number of sex partners and are more willing to engage in casual sexual encounters or "one-night stands" than w o m e n (e.g., Buss 1994; Buss and Schmitt 1993; Clark and Hatfield 1989; Ford and Beach 1951; Symons and Ellis 1989). In addition, in choosing partners for both shortand long-term relationships men focus on physical attributes positively correlated with a woman's reproductive value, fertility, or fecundity, such as youthful appearance, smooth skin, lustrous hair, facial or general attractiveness, and bodily proportions such as small waist-to-hip ratio (WHR) (e.g., Buss 1989; P~russe 1994; Singh 1993; Symons 1979). By choosing women with these qualities for sexual liaisons, men enhance their fitness through the heightened probability of conception. Numerous researchers have confirmed women's general preference for men with resources or personality qualities indicative of the ability to garner resources. For example, P~russe (1994) found that social status was positively related to the number of partners men acquire, whereas a woman's social status was not a significant criterion for male mate choice. Buss (1989) reported that w o m e n valued "good financial prospect" and such correlated personality characteristics as "ambition and industriousness" in a potential mate more than men. Fewer researchers have examined whether personality variables indicative of a man's willingness to .care for offspring, such as parental aptitude, influence w o m e n ' s mate choice decisions. In addition, although men primarily focus on a potential
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mate's physical attractiveness (Buss 1989; Feingold 1990; Symons and Ellis 1989), the role of men's physical traits in women's mating decisions has received limited attention with the exception of recent reports that w o m e n find men with symmetrical body proportions more attractive than asymmetrical men (e.g., ThornhiU and Gangestad 1994). Body symmetry m a y be a selection criterion for w o m e n insofar as it reflects "good genes" and is associated with male reproductive success and developmental stability (Thornhill and Gangestad 1994). Although a woman's choice of a mate appears to be influenced by both a man's physical attractiveness and his personality characteristics, less is k n o w n about their relative or interaction effects. Presumably, where individual males possess combinations of attributes having diverse effects on female fitness, w o m e n m a y be expected to make adaptive trade-offs between such characteristics. Buss and Schmitt (1993) convincingly argue that, in addition to the stratagems described above, men and w o m e n employ different strategies depending on whether a potential relationship is short- or long-term. In general, men are expected to pursue short-term strategies more than are w o m e n (Buss 1994; Buss and Schmitt 1993; Symons 1979). An underlying assumption of the present study is that engaging in short-term, casual sexual relationships involves more costs for women, including the risk of physical aggression and reduced male parental investment in offspring. Sexual dimorphism in body size increases women's vulnerability to acts of physical violence or sexual coercion that could lower fitness through injury or by eclipsing the choice of a mate motivated to invest in offspring. Therefore, women should be wary of forming consortships with unfamiliar partners, particularly those who exhibit a potential for physical aggression. Women's evolved psychologies should result in fear and avoidance of situations where their lives or reproductive choices are jeopardized. Wart (1985:242) found that, among young urban women, rape is feared more than any other offense; he concluded, "it is beyond question that rape is currently a central fear in the lives of a large proportion of women." He also noted that fear of rape was greatest among w o m e n with the highest fecundity and that it severely restricted women's activities, especially their probability of venturing outside the home alone or at night. Buss and Schmitt (1993) and Buss (1994) suggest that the presence of aggressive men would have been an important factor in shaping w o m e n ' s mate selection criteria. However, they did not suggest that w o m e n should avoid aggressive men in short-term matings, but rather that they should choose short-term mates who will protect them from the aggression of other men. Based on this assumption, these authors predicted and found some evidence that women value the combined attributes of size and strength in short-term mates. Their investigation, however, did not address the issue that greater size and strength may enable a male to s u b d u e
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or threaten another male but can also pose serious risks to a woman. A w o m a n may be more willing to initiate a casual relationship with a man if the risks are attenuated by the possession of characteristics indicating he is not a threat or is "safe." In contrast, because the risk of physical aggression from w o m e n would not be great for men, fear of aggression would not be expected to play an important role in shaping male mate selection criteria. Although male parental care is relatively rare in mammalian species, males tend to invest more in offspring w h e n they have exclusive, enduring relationships with females (Daly and Wilson 1983, 1988). Hence, one of the benefits of w o m e n forming long-term relationships with men is the acquisition of additional parental investment for offspring, beyond that provided by themselves and their kin. Thus, the benefit of heightened paternal investment should result in a female preference for long-term, rather than short-term, relationships. However, a w o m a n may be willing to engage in a short-term sexual relationship if there is a possibility that it might lead to an enduring relationship or if a male demonstrates his willingness to invest in offspring. Conversely, we would not expect a woman's parental qualifies to be highly weighted among men's mate selection criteria. Maternal behavior in mammals has more likely been selected from the presence of the fetus in utero, or gestation-driven selection (Surbey 1998), and the production of altricial young, rather than through sexual selection. Regardless of male mate selection criteria, a mammalian female not exhibiting adequate parental behavior would have reduced fitness compared with one who did. As a result, although there have been strong selection pressures on men to choose w o m e n with physical attributes signalling high fecundity or fertility, there would have been less selection on men to place high value on women's parenting behavior. In a sense, from a man's point of view, maternal behavior in w o m e n is a given, and where there is little variance in a quality, there would be less selection to discriminate between potential partners on that trait (P6russe 1994). Crossculturally men prefer chaste, sexually inexperienced w o m e n for long-term partners, with physical characteristics indicating high reproductive value (e.g., low waist-to-hip ratio; Buss 1989; Singh 1993). Presumably such characteristics are negatively correlated with age, parity, and well-developed maternal behaviors. Therefore, selection for male preferences for the former set of characteristics could, if anything, nullify or select against male preferences for the latter qualities. Although counter-intuitive, this possibility deserves empirical investigation. To recap, if engaging in short-term sexual relationships is more costly for w o m e n than for men, then minimizing the perceived risks or increasing the benefits may heighten women's willingness to engage in casual sexual relationships. Women should be more willing to engage in short-
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term relationships if they may become long-term, or if a man appears willing to invest in children and does not pose a physical threat. Although both men and w o m e n should value physical attractiveness in a potential partner, w o m e n m a y trade off physical attractiveness (an indicator of "good genes") for certain personality characteristics more so than men. For instance, a w o m a n might be more likely to engage in a short-term relationship with a less attractive man if he appears parental or safe, compared with an attractive man without those qualities. Such trade-offs would result in physical attractiveness having a smaller overall effect on female choice than men's selection strategies. In order to test these propositions we manipulated the perceived costs and benefits associated with engaging in a casual sexual encounter based on a survey originated b y Symons and Ellis (1989). These researchers asked men and w o m e n to indicate their willingness to have sexual intercourse with a hypothetical partner when there was no risk of pregnancy, discovery, or disease. In the first condition no information about the imagined partner's personality was provided, whereas in the second condition they were assigned many positive attributes and the possibility of forming a long-term relationship was raised. In both conditions the relative attractiveness of the potential partner was manipulated and participants were to indicate their willingness to engage in sexual intercourse when the partner was equally, less, or more attractive than themselves. Symons and Ellis (1989) found that men were more willing than w o m e n to have sexual intercourse with an unfamiliar person and that a partner's relative level of attractiveness had a greater effect on men's responses. Women exhibited a heightened willingness for intercourse w h e n there was a possibility of a more enduring relationship and partners were assigned multiple positive characteristics. Unfortunately, these two factors were confounded in the second condition, so their relative effects could not be discerned. For the purposes of the present investigation we adapted the survey method employed by Symons and Ellis (1989) in order to manipulate the characteristics of a potential partner as well as the length of the potential relationship while eliminating this confound. SUMMARY OF PREDICTIONS TESTED When presented with the hypothetical opportunity to engage in sexual intercourse with an unfamiliar partner of the opposite sex, where there is no risk of pregnancy, discovery, or disease: 1.
Men should report a greater willingness to engage in sexual intercourse than w o m e n across all conditions (a replication of the findings of Symons and Ellis 1989).
372 2.
3.
4.
Human Nature, Vol. 11, No. 4, 2000 A woman's willingness to engage in sexual intercourse should be greater when the possibility of forming a long-term relationship exists, whereas the length of a potential relationship should not affect men's willingness. The attractiveness of a potential partner should influence both men's and women's willingness to engage in sexual intercourse. However, because w o m e n are expected to trade off physical attractiveness and personality attributes more so than men, the relative attractiveness of a potential partner should have a greater effect on men's responses. Among women, personality characteristics indicative of low risk of aggression, or parental aptitude, may compensate for a lower level of attractiveness in a potential mate, whereas such trade-offs would occur to a much lesser degree among men. Women, but not men, should be more willing to have sexual intercourse with imagined partners w h o are described as unaggressive (safe) or parental, compared with those not given any descriptors.
METHOD
Participants One hundred men and an equal number of w o m e n (mean ages of 21.43 and 20.2 years, respectively) attending St. Thomas University in N e w Brunswick, Canada, participated in this study b y completing an anonymous questionnaire. Because w o m e n are over-represented in undergraduate populations, we sampled more widely (in more classes b e y o n d the first year) for male participants, and as a result, they tended to be older than the females, F(1, 198) = 10.08, MS = 75.34, p < .0017. However, regression analysis revealed that age was not a significant predictor of participants' willingness to engage in a sexual encounter, R 2 (adjusted) = .002, F(1,196) = .54, MS = .29, n.s. Most participants were Caucasian and all were heterosexual. Students currently married or cohabiting with a partner were excluded from participation in order to reduce the possibility 'that responses w o u l d be biased by their current involvement in a relationship.
Materials The questionnaire items were adapted from Symons and Ellis (1989) and consisted of a series of short descriptive vignettes describing four hypothetical, unfamiliar individuals of the opposite sex. After reading each item, participants were asked to indicate their willingness to have sexual intercourse with the imagined individual if there was no risk of pregnancy, discovery, or disease. In the first condition, the imagined partner was not
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assigned any behavioral or personality characteristics (basic condition). In the remaining conditions, they were either described as being non-physically aggressive (safe condition) or possessing positive parental qualities (parental condition) or multiple positive personal attributes (multiple condition). The first and last descriptions (basic and multiple conditions) were borrowed directly from Symons and Ellis (1989) to serve as control or anchor conditions. We expected participants would respond most positively to imagined partners described as having numerous positive characteristics. The inclusion of a vignette without descriptors served as a control for the conditions where partners were described as being "safe" or "parental," which were the primary focus of this investigation. In addition to varying the behavioral and personality characteristics of imagined partners, the possibility of forming a long-term relationship was introduced by including pairs of items in each condition. In the first item of each pair only the possibility of having sexual intercourse was described, whereas the second item raised the possibility of forming a long-term relationship. After reading each item, participants responded to a three-part question by indicating their expected willingness to have sexual intercourse w h e n the partner was equally, more, or less attractive than themselves. Responses were coded using a four-point Likert scale with high scores indicating a greater willingness to engage in a casual sexual encounter. Sample questionnaire items are included in the appendix. In order to minimize expectancy effects engendered by participants identifying the relevant differences in the test items (a concern in withinsubjects designs), the pairs of vignettes were interspersed between four other sets of "distracter" questions relating to mate selection criteria. These items included questions about the physical characteristics preferred in a mate, rankings of a mate's characteristics in terms of importance, and an open-ended question asking participants to describe their ideal mate. The pairs of target vignettes appeared between the distracter items in ten random orders. To further reduce opportunities for conscious comparison of vignette contents, participants were instructed to complete the items quickly and not to go back through the questionnaire a n d / o r alter their responses. RESULTS Sex Differences in Anticipated Willingness to Have Sexual Intercourse with an Imagined Partner
In order to test the predictions, an ANOVA with one between- and three within-subjects factors (Sex of Participant • Length of Potential Relationship x Relative Attractiveness x Personality Characteristics) was conducted
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Table 1. ANOVA Results for the Effects of Sex, Length of Relationship, and Relative Attractiveness and Assigned Personality Characteristics of the Potential Partner on Participants' Anticipated Willingness to Engage in Sexual Intercourse Source
df
SS
MS
F
p
Sex Length Length x Sex Attractiveness Attractiveness x Sex Characteristics Characteristics x Sex Length x Attractiveness Length x Attractiveness x Sex Length x Characteristics Length x Characteristics x Sex Attractiveness x Characteristics Attractiveness x Characteristics x Sex Length x Attractiveness x Characteristics Length x Attractiveness x Characteristics x Sex
1 1 1 2 2 3 3 2 2 3 3 6 6
679.09 74.09 44.14 199.28 46.00 21.12 4.12 .11 .091 1.38 .48 .92 .69
679.09 74.09 44.14 99.64 23.00 7.04 1.37 .06 .045 .46 .16 .15 .12
71.73 43.81 26.10 154.72 35.70 14.41 2.81 .53 .43 1.60 .56 1.71 1.29
.00005 .00005 .00005 .00005 .00005 .00005 .019 n.s.* n.s.* n.s.* n.s.* n.s.* n.s.*
6
.17
.029
.54
n.s.*
6
.41
.068
1.29
n.s.*
*two-tailed test on participants" reported willingness for sexual intercourse. Results are s u m m a r i z e d in Table 1. (Note: A n alpha level of .05 w a s u s e d for all tests. Because most predictions were directional, all r e p o r t e d p-values are onetailed, unless otherwise indicated.) O v e r all conditions participants" m e a n willingness score (out of a m a x i m u m of four) was 2.51, w i t h m e n (M = 2.89) indicating a significantly greater willingness to h a v e sexual intercourse w i t h a hypothetical partner than w o m e n (M = 2.13). A l t h o u g h m e n a n d w o m e n differed in age, a d d i n g age to the m o d e l as a covariate a n d cond u c t i n g a n A N C O V A did not r e d u c e the overall effect of sex or c h a n g e the general p a t t e r n of results. Effect of Varying the Length of the Relationship Relationship length also h a d a significant main effect o n responses: the possibility of forming a long-term relationship elevated participants' anticipated willingness to have intercourse w i t h a n otherwise unfamiliar individual (M = 2.63 and 2.38 for long- and short-term conditions, respectively). As predicted, this main effect was qualified b y a significant interaction b e t w e e n the sex of the participant a n d relationship length (Figure 1). P l a n n e d comparisons revealed that w o m e n r e p o r t e d a greater willing-
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4.0
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Figure 1. Men's and women's anticipated willingness (mean _ s.e.) to engage in sexual intercourse with a hypothetical partner when the relationship was short-term versus where there was a possibility of forming a long-term relationship. ness to engage in sexual intercourse w i t h a hypothetical p a r t n e r w h e n there was a chance of forming a l o n g - t e r m relationship, F(1, 99) = 80.78, MS = 117.48, p < .00005, whereas this m a n i p u l a t i o n did not affect m e n ' s responses, F(1, 97) = .99, MS = 1.91, n.s. Effect of M a n i p u l a t i n g the Relative Level of Attractiveness of the H y p o t h e t i c a l P a r t n e r Both the main effect of the hypothetical p a r t n e r ' s relative attractiveness and the interaction b e t w e e n the sex of the participant and level of attractiveness w e r e statistically significant (Figure 2). Both m e n a n d w o m e n
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Figure 2. The effect of the hypothetical partner being equally, less, or more attractive than the participant on men's and women's expected willingness to engage in sexual intercourse (mean +_ s.e.). indicated heightened intentions to have sexual intercourse with hypothetical partners more attractive than themselves compared with partners described as equally attractive. An ANOVA conducted on the difference in willingness scores when the imagined partner was equally versus more attractive confirmed that men's and w o m e n ' s responses were similarly affected by increasing the attractiveness of hypothetical partners, F(1, 196) = .44, MS = .022, n.s. However, a second ANOVA employing difference scores showed that when the imagined partner was described as being less attractive than the participant, men's scores declined significantly more than women's compared with items where the partner was described as being equally attractive, F(1, 197) = 48.06, MS = 8.242, p < .00005. Therefore,
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while men's and women's responses were affected in the same direction by manipulating the attractiveness of the potential partner, men's scores were affected more than women's when the partner was described as being less attractive than themselves. Furthermore, pairwise comparisons revealed that w o m e n were as willing to have sexual intercourse with a hypothetical male w h o was described as less attractive than themselves but exhibiting parental traits compared with one who was equally attractive but not assigned any positive characteristics (basic condition), F(1, 99) = 0.00, MS = 0.00, n.s. This pattern of responses was not observed among male participants. The effect of attractiveness was so much greater among men that it did not appear to be counteracted by the possession of such attributes. In contrast to the women, men were far more willing to have intercourse with a partner equally attractive to themselves but not exhibiting any other characteristics (basic condition) compared with one who was less attractive but possessing positive parental qualities, F(1, 97) = 255.64, MS = 29.21, p < .0001.
Effect of Varying Behavioral and Personality Characteristics of the Hypothetical Partner Altering the personality and behavioral characteristics attributed to the imagined partner had a significant effect on participants" responses. In general, anticipated willingness to have sexual intercourse was greatest when the partner was described as having many positive characteristics (M = 2.61), lowest when characteristics were not assigned (M = 2.43), and intermediate when the potential partner was described as parental or safe (M = 2.52 and 2.46, respectively). As expected, there was a significant interaction between sex of participant and characteristics of the imagined partner. As shown in Figure 3, the significant interaction was the result of the imagined partner's characteristics having a lesser effect on men's responses. Planned comparisons revealed women's heightened willingness for sexual intercourse when a hypothetical partner was described as parental, F(1, 99) = 13.20, MS = 1.027, p < .0002, and a trend in the same direction when the individual was described as safe, F(1, 99) = 1-.83, MS = .14, p < .09, in comparison with conditions where descriptors were not assigned. Conversely, men's willingness to have intercourse did not change as a function of describing the potential partner as parental or safe (compared with the basic condition: F(1, 98) = .90, MS = .056, n.s., and F(1, 98) = .06, MS = .004, n.s., respectively). Men's and women's results were examined separately to determine if personality characteristics had different effects on willingness scores depending on whether the relationship was only casual or potentially long-
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3.0-
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2.8-
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2.6"
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Figure 3. Interaction between the effects of participant's sex and the personality and behavioral characteristics of the hypothetical parmer on anticipated willingness to engage in sexual intercourse (mean +- s.e.).
term. The interaction b e t w e e n personality characteristics and length of relationship was not significant for either sex, F(3, 97) = .85, MS = .24, n.s., for m e n and F(3, 99) = 1.31, MS = .38, n.s., for w o m e n , suggesting that the relative weighting of personality characteristics was similar across short- a n d long-term contexts for b o t h sexes. Post hoc c o m p a r i s o n s b e t w e e n the parental and safe conditions w i t h i n each context s h o w e d that w o m e n ' s willingness for sex in the short-term condition was greater w h e n a h y p o thetical male was described as parental v e r s u s w h e n h e was described as safe, F(1, 99) = 9.61, M S = 2.8, p < .002 (two-tailed), b u t this difference was not significant in the long-term context, F(1, 99) = .97, MS = .28, n.s. (twotailed). The only difference n o t e d in the v a l u a t i o n of characteristics b y m e n was that they were m o r e willing to h a v e intercourse w i t h a w o m a n in the multiple v e r s u s basic condition in a potentially l o n g - t e r m relationship,
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F(1, 97) = 10.60, MS = 3.0, p < .001 (two-tailed), whereas responses to these conditions were not significantly different in the short-term context, F(1, 97) = 1.74, MS = .49, n.s. (two-tailed).
DISCUSSION A consideration of past selective pressures suggests that men and w o m e n generally employ different reproductive strategies that m a y vary as a function of whether a relationship is short- or long-term (Buss and Schmitt 1993; Symons 1979; Trivets 1972). In the present study w e focused primarily on mating decisions in hypothetical short-term sexual encounters, although the potential for forming a long-term relationship was also manipulated. Consistent with theoretical expectations and previous findings, male participants reported a greater willingness to engage in a casual sexual encounter across all conditions compared with women. Even when a hypothetical partner was assigned numerous positive characteristics, a highly significant sex difference remained. In addition, women's, but not men's, reported inclination to engage in a sexual encounter was heightened by the possibility of forming a long-term relationship. Presumably the formation of a long-term relationship increases the parental investment available for subsequent children, and this possibility weighs heavily in women's decisions to engage in casual sex. While a potential partner's relative physical attractiveness was important to both sexes, attractiveness had greater effects on men's responses. Both men and w o m e n were significantly more willing to engage in intercourse with a partner w h o was more attractive than themselves than with one w h o was equally attractive to themselves. Where little else is to be gained from a relationship, a focus on attractiveness, insofar as it signifies "good genes," may be the best strategy for women. Although both sexes were similarly affected by increasing a partner's attractiveness, men's reported desire for intercourse was significantly reduced compared with women's if a potential partner was described as being less attractive than themselves. These findings diverge somewhat from those of Symons and Ellis (1989), w h o found that decreasing the imagined partner's relative physical attractiveness reduced women's willingness for sexual intercourse, whereas women's willingness to have intercourse with a man w h o was more attractive than or equally attractive as themselves was equivalent. Nevertheless, taken together both sets of findings suggest that while the attractiveness of a potential mate is important to both men and women, it has a greater impact on men's responses. An alternative interpretation is that men are more likely to discriminate among potential partners based on their physical attractiveness than are women. In this vein
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Kenrick et al. (1990) found that men were clearly more selective than w o m e n when a partner's physical attractiveness was considered. A number of researchers have examined the personality and behavioral characteristics important in the selection of romantic partners. For exampie, Buss (1985) found that both men and w o m e n desire partners w h o are, above everything else, "kind and understanding." Although one interpretation of this finding is that large sex differences do not exist in the valuation of the most important characteristics in a potential mate, there is an alternative explanation: "Kind and understanding" have different connotations for men and women. In particular, for women, describing a man in this w a y may indicate that he is gentle and poses little physical danger to them, or is nurturant and would be a good father. Our expectation that low risk of physical aggression and parental qualities in a partner w o u l d be valued b y women, but not b y men, in mating decisions was based on this supposition. Men do not generally face the same risk of physical harm or sexual coercion as do w o m e n w h e n they encounter unfamiliar Individuals of the opposite sex. In addition, because the offspring is the major selective agent on parental behavior in females, we did not expect male psychology to reflect a strong preference for w o m e n described as maternal. In fact, as discussed in a previous section, men may prefer w o m e n w h o have not yet adopted parental mannerisms because their correlated physical features are highly attractive to men. Our results confirmed that w o m e n reported a greater inclination for sexual intercourse with males w h o were described as parental and safe (a trend) in comparison with males not given descriptors (basic condition), whereas males did not differentiate between these conditions. Describing a potential partner as "safe" did not have as great an effect as anticipated. This marginal result may be an accurate reflection of women's preferences, b u t it could also be a consequence of the particular wording chosen to describe the potential partner in that condition. For that item we chose the colloquial phrase " w o u l d not hurt a fly" to imply that the individual did not pose a physical threat. However, this wording may have resulted in some w o m e n considering the potential partner not just non-threatening but weak or "wimpy," and this could have reduced, rather than increased, their willingness to have sexual intercourse with him. Repeating this manipulation using a different phrase conveying a low risk of aggression might provide a better test of the original prediction. Although few studies have focused directly on the roles of physical risk and parental qualifies in mating decisions, some previous findings lend indirect support to those reported here. For example, prosocial qualities in a man (e.g., agreeableness) tend to increase his attractiveness to w o m e n and moderate the effects of other qualities, such as dominance (Jensen-
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Campbell et al. 1995; Graziano et al. 1997). Dominance, which could include an aspect of threat, appears to increase women's attraction to hypothetical partners only when paired with prosocial characteristics. Kenrick et al. (1990) examined the minimum acceptable level for "kindness and understanding" in one's partners in different relationship contexts. They found that the minimum acceptable level of these qualities w a s significantly greater for w o m e n than men w h e n the relationship became one defined by sexual involvement. In addition, these same authors reported that men generally valued "aggressiveness" in a partner more than women, although this difference did not reach statistical significance. Moreover, Kenrick et al. (1990) noted that w o m e n valued "wanting children" in a partner more than men did, although the difference was statistically significant in only one of their experimental conditions. Buss and Barnes (1986) also reported a sex difference in the valuation of the characteristic "fond of children" in a potential mate, with w o m e n valuing this attribute more than men.
Gangestad (1993) argues that while preferences for physical attractiveness (as a measure of "good genes") exist, individuals also make trade-offs between a mate's physical attractiveness and investment potential. We concur with the notion that when males vary in terms of gene quality and potential parental investment, females should be selected to choose males with the highest joint combination of these qualities. However, because female parental behavior is relatively invariant, we question the suggestion that men should trade off indicators of a partner's genetic quality and potential investment to the same degree as women. For the w o m e n in our sample, a hypothetical partner's relative unattractiveness was offset b y describing him as parental. In men, however, the possession of parental qualities did not appear to compensate for a potential partner being less attractive than themselves. Although our experimental design permitted the control and manipulation of a number of relevant variables, our findings possess certain inherent limitations. For example, our results are specific to mate selection criteria in the context of short-term sexual relationships and m a y not generalize to other types of relationships. There are theoretical reasons for expecting the greatest sex differences in selectivity in casual sexual relationships. Kenrick and colleagues (1990) argue that when a relationship is casual and anticipated investment in the relationship is low (e.g., as in a casual dating relationship) there should be little difference in men's and women's selectivity of partners. Consistent with this, they found greater gender differences in selectivity for a sexual partner than for a dating partner or in more committed relationships. They further suggested that w h e n dealing with courtship at the level of a single date, neither sex is invested
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and thus they both should be equally less selective. With sexual relationships w o m e n risk a significantly larger investment than do men and thus should have higher expectations about a partner's characteristics than men. When a relationship involves a serious commitment, both sexes are highly invested and their selectivity should be equally high. In a subsequent extension of this work, Kenrick et al. (1993) found that w o m e n were more selective than men when considering sexual partners, especially at the level of a one-night stand. Similar to our findings, among those characteristics weighted highly important for w o m e n in this context were "family orientation" and "agreeableness." Like Kenrick et al. (1990, 1993), Regan (1998) reported the greatest sex differences in mate selection standards in short-term mating contexts. Suggesting that people may compromise their standards for ideal partners, Regan found that w o m e n were least willing to do this in short-term mating situations. In general, men showed greater latitude in applying standards to casual sex partners compared with long-term romantic partners, whereas w o m e n ' s ideal standards did not vary as a function of the relationship context. Our study tested differential selectivity w h e n the relationship was primarily a casual sexual relationship; thus, according to Kenrick et al.'s (1990) logic, we would expect maximum sex differences under these conditions. However, contrary to those authors' assumptions, and more in line with Regan's results (1998), we found that, where there was a possibility for a long-term relationship, men's and women's mate selection criteria did not significantly change. For example, it did not appear that w o m e n valued parental qualities relatively more in a potentially long-term versus a short-term mate. Our methods involved an examination of participants' intentions and responses to hypothetical situations rather than their actual mate choice. Insofar as intentions are known to be a reliable predictor of people's behavior, one would expect the external validity of such self-reported preferences to be reasonable (Eagly and Chaiken 1993; Fishbein and Ajzen 1975). Moreover, although studying people's intentions may be problematic, there are at least as many limitations to overcome when attempting to study actual behavior in real-world situations. First of all, studies conducted in naturalistic contexts generally lack controls for relevant variables. In the ancestral human environment casual sex w o u l d have involved some risk of pregnancy, discovery, or disease, but these risks would have been variable. Our design controls for this variability by eliminating such risks entirely. Secondly, behavior is readily modifiable and may not always accurately reflect underlying dispositions and psychological mechanisms. By employing an experimental design based on hypothetical situations, and removing typical constraints on people's behavior, we may have tapped into their underlying desires more than w o u l d be
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possible using behavioral methods. For this same reason, studying people's fantasies may provide a better picture of their proclivities than examining their actual behaviors (Buss 1994; Ellis and Symons 1990). Participants in the present study were relatively young adults, and their responses might have been different had they been older and more experienced. Like Cashdan (1993), we considered the possibility that the preferences exhibited by male participants might be a function of their willingness to "settle down" or their developmental stage. Kenrick et al. (1990) argue that selectivity should become more equivalent across the sexes with increasing age. For example, older men may value a woman's maternal qualifies more than younger men as a result of experience or an increased focus on partner quality, rather than quantity, as their ability to attract multiple mates declines with age. If w o m e n tend to be more developmentally advanced than men, then their greater selectivity may be a developmental effect rather than a sex difference. Our results, however, argue against the observed sex differences being purely a function of age differences. Age was not a significant covariate of willingness to engage in sexual intercourse, and the men in our sample, while older on average, were less, not more, selective than the women. Sprecher et al. (1994) conducted a large national study of mate selection criteria and found that gender differences in mate selection criteria were not dependent on age. Although they did not examine criteria identical to those in the present study, their findings suggest that our results, albeit restricted to a youthful sample, may be generalizable to the population at large. Even if it was found that the magnitude of sex differences changed with age, the average age of our participants would have coincided with the age at which mate selection and first reproduction would have begun in the ancestral environment. Thus, our findings may be especially pertinent to understanding evolved sex differences in mate choice at the point in the h u m a n life cycle when these activities are typically at their peak. We thank J. Gillis and C. Ng for advice on the design of this study, and the Evolutionary Psychology Group and Psychology Department at Simon Fraser University for their support while the first author was on sabbatical and completed the manuscript. The data were collected in partial fulfillment of the requirements for a degree with honors granted to C. Conohan. Michele K. Surbey is currently a Senior Lecturer at James Cook University where she teaches courses in evolutionary psychology. Her research and theoretical interests include the evolution of development, environmental effects on pubertal timing, human mate selection, and the evolution of self-deception. Colette D. Conohan received her B.A. (Honours) at St. Thomas University and later completed her master's degree at Laurentian University.
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APPENDIX Sample Questionnaire Items All answers took the following form: Certainly not 1
Probably not 2
Probably would 3
Certainly would 4
Short-Term Condition a. If the opportunity presented itself to have sexual intercourse with an anonymous member of the opposite sex who was as physically attractive as yourself but no more so (and who you overheard a friend describe as being [**]), do you think that if there was no chance of forming a more durable relationship, and no risk of pregnancy, discovery, or disease, that you would do so? Please circle the appropriate number. b. What if the person was somewhat less physically attractive than yourself? c. What if the person was somewhat more physically attractive than yourself? Long-Term Condition a. Suppose there was a chance of forming a more durable relationship with this person (who was described as being [**]). N o w suppose that again the opportunity presented itself to have sexual intercourse with this person. Do you think, if the person was as physically attractive as yourself but no more so, that you would do so? b. What if the person was somewhat less physically attractive than yourself? c. What if the person was somewhat more physically attractive than yourself? ** Descriptors Employed (except in the Basic Condition, where the parenthethical phrase was not included):
Safe Condition: "a well-liked and trusted individual who w o u l d never hurt a fly"
Parental Condition: "a well-liked and generous person who volunteers in a day care centre and is fond of children" Multiple Condition: "a bright and generous individual with a sense of humour, who shares time freely, is weU-liked by others, is a successful architect, is fond of children, likes to travel, and is a serious amateur runner" (from Symons and Ellis 1989)
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REFERENCES Bateman, A. J. 1948 Intra-sexual Selection in Drosophila. Heredity 2:349-368. Buss, D. M. 1985 Human Mate Selection. American Scientist 73:47-51. 1989 Sex Differences in Human Mate Preferences: Evolutionary Hypotheses Tested in 37 Cultures. Behavioral and Brain Sciences 12:1-49. 1994 The Evolution of Desire. New York: Basic Books. Buss, D. M., and M. Barnes 1986 Preferences in Human Mate Selection. Journal of Personality and Social Psychology 50:559-570. Buss, D. M., and D. P. Schmitt 1993 Sexual Strategies Theory: An Evolutionary Perspective on Human Mating. Psychological Review 100(2):204-232. Cashdan, E. 1993 Attracting Mates: Effects of Paternal Investment on Mate Attraction Strategies. Ethology and Sociobiology 14:1-24. Clark, R. D., and E. Hatfield 1989 Gender Differences in Receptivity to Sexual Offers. Journal of Psychology and Human Sexuality 2:39-55. Daly, M., and M. Wilson 1983 Sex, Evolution, and Behavior, second ecl. Boston: PWS. 1988 Homicide. New York: Aldine de Gruyter. Eagly, A. H., and S. Chaiken 1993 The Psychology of Attitudes. Fort Worth: Harcourt Brace Jovanovich. Ellis, B. J., and D. Symons 1990 Sex Differences in Sexual Fantasy: An Evolutionary Psychological Approach. Journal of Sex Research 27:527-556. Feingold, A. 1990 Gender Differences in Effects of Physical Attractiveness on Romantic Attraction: A Comparison across Five Research Paradigms. Journal of Personality and Social Psychology 59(5):981-993. Fishbein, M., and I. Ajzen 1975 Belief, Attitude, Intention and Behavior: An Introduction to Theory and Research. Reading, Massachusetts: Addison Wesley. Ford, C. S., and F. A. Beach 1951 Patterns of Sexual Behavior. New York: Harper & Row. Gangestad, S. W. 1993 Sexual Selection and Physical Attractiveness: Implications for Mating Dynamics. Human Nature 4:205-235. Graziano, W. G., L. A. Jensen-Campbell, M. Todd, and J. F. Finch 1997 Interpersonal Attraction from an Evolutionary Psychology Perspective: Women's Reactions to Dominant and Prosocial Men. In Evolutionary Social Psychology, J. A. Simpson and D. T. Kenrick, eds. Pp. 141-167. Mahwah, New Jersey: Erlbaum.
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Jensen-Campbell, L. A., W. G. Graziano, and S. G. West 1995 Dominance, Prosocial Orientation, and Female Preferences: Do Nice Guys Really Finish Last? Journal of Personality and Social Psychology 68:427439. Kenrick, D. T., G. E. Groth, M. R. Trost, and E. K. SadaUa 1993 Integrating Evolutionary and Social Exchange Perspectives on Relationships: Effects of Gender, Self-Appraisal, and Involvement Level on Mate Selection Criteria. Journal of Personality and Social Psychology 64:951-969. Kenrick, D. T., E. K. Sadalla, G. Groth, and M. R. Trost 1990 Evolution, Traits, and the Stages of Human Courtship: Qualifying the Parental investment Model. Journal of Personality 58:97-116. P6russe, D. 1994 Mate Choice in Modem Societies: Testing Evolutionary Hypotheses with Behavioral Data. Human Nature 5:255-278. Regan, P. C. 1998 What If You Can't Get What You Want? Willingness to Compromise Ideal Mate Selection Standards as a Function of Sex, Mate Value, and Relationship Context. Personality and Social Psychology Bulletin 24:1294--1303. Singh, D. 1993 Adaptive Significance of Female Physical Attractiveness: Role of Waistto-Hip Ratio. Journal of Personality and Social Psychology 65:293-307. Sprecher, S., Q. Sullivan, and E. Haffield 1994 Mate Selection Preferences: Gender Differences Examined in a National Sample. Journal of Personality and Social Psychology 66:1074-1080. Surbey, M. K. 1998 Developmental Psychology and Modem Darwinism. In Handbook of Evolutionary Psychology: Ideas, Issues and Applications, C. B. Crawford and D. Krebs, eds. Pp. 369--404. Hillsdale, New Jersey: Erlbaum. Symons, D. 1979 The Evolution of Human Sexuality. New York: Oxford University Press. Symons, D., and B. Ellis 1989 Human Male-Female Differences in Sexual Desire. In The Sociobiology of Reproductive Strategies, A. Erach, C. Vogel, and E. Voland, eds. Pp. 131-146. New York: Chapman and Hall. Thomhill, R., and S. W. Gangestad 1994 Human Fluctuating Asymmetry and Sexual Behavior. Psychological Science 5:297-302. Trivers, R. L. 1972 Parental Investment and Sexual Selection. In Sexual Selection and the Descent of Man, 1871-1971, B. Campbell, ed. Pp. 136-179. Chicago: Aldine. Warr, M. 1985 Fear of Rape among Urban Women. Social Problems 32:238-250.