Disco clothing, female sexual motivation, and relationship status: is she dressed to impress?

Journal of Sex Research, Feb, 2004 by Karl Grammer, LeeAnn Renninger, Bettina Fischer

Evolutionary theory explains sex differences in sexuality and mate selection criteria in terms of different levels of parental investment (Symons, 1979; Trivers, 1972). For women, the minimum required parental investment is greater than it is for men. A copulation that requires minimal male investment can produce a 9-month investment for the woman that is substantial in terms of time, energy, resources, and foreclosed alternatives. As a result, women will tend to be more discriminating in their choice of a mating partner and will be less interested in short-term relationships than will men. Women will prefer characteristics in potential mates that signal the possession or likely acquisition of resources that could aid them and any potential offspring in the long term (Buss, 1988; Buss & Schmitt, 1993).

Men, in contrast, will tend toward a different strategy. Since males' necessary investment is minimal, men can afford to be less choosy when it comes to mating partners. Men will be interested in a variety of short-term partners, will be more open to low-investment sexual opportunity, and will tend to focus on cues signaling fertility and reproductive health rather than resource-acquisition skills (Townsend & Levy, 1990). Since female fertility is limited by health and age, male sexual attraction will primarily be attached to visual stimuli such as muscle tone, facial and body proportions, and absence of wrinkles. The existence of these mate selection tendencies has been demonstrated many times (Cunningham, 1986; Singh, 1993; Townsend, 1989; Townsend, Kline, & Wasserman, 1995).

The consequences of male versus female minimal parental investment can also be seen in present-day sex motivation systems. Males have a lower threshold for sexual excitation (Rubin, 1970), tend to perceive people and relationships in a more sexualized manner (Abbey, 1982), and are more likely to interpret a variety of stimuli as signals of sexual intent (see Gross, 1978; Kanin, 1969). Since low-investment copulation was advantageous for males in our evolutionary past, males are predisposed to attend carefully to potential sexual cues and be on the lookout for any signals that might indicate varying degrees of sexual openness.

ALTERNATIVE REPRODUCTIVE STRATEGIES

In Westernized societies the mating system is presumptively monogamous, but research shows that it is probably more accurate to describe our mating system as one of serial polygamy: Successive marriages and mating outside of marriage and committed relationships are common (Buss & Barnes, 1986). Estimates based on DNA evidence suggest that 9% to 13% of children have putative fathers that are not their genetic fathers (Baker & Bellis, 1995). Adultery among married couples is estimated to range from 26% to 70% for women and from 33% to 75% for men (Hite, 1976; Kinsey, Pomeroy, Martin, & Gebhard, 1953; Symons, 1979).

To maximize our reproductive success, it makes sense that evolution has outfitted both males and females with several possible mating strategies. For males, a dual sexual strategy is likely to have been most profitable in the evolutionary past: Invest in offspring with a female who has been selected for fertility and fidelity, but take advantage of any other low-investment mating opportunities that come along. Signals of fidelity and sexual restraint will be of value in a long-term partner, as this will help to increase a male's confidence of paternity in invested offspring. Signals of sexual openness, on the other hand, will be of value in a short-term partner.

For females, the main sexual strategy will be to carefully select a mate with whom a long-term, committed relationship can be established, and from whom resources for potential offspring in the future can be secured. Mating outside a committed relationship (extra-pair copulations or EPCs) with a carefully selected male could, however, also be an adaptive mating strategy for a female for the following reasons: The simultaneous competition of the sperm from two different males for the fertilization of the egg will provide for increased genetic quality in the offspring, genetic variability among a female's offspring will enhance inclusive fitness and survival prospects, the female can increase her prospect of acquiring a better mate, and the female can benefit from immediate resource accrual provided by her EPC partners (Gangestad & Thornhill, 1998; Pound, 1998; Symons, 1979; for a review of additional hypothesized benefits see Greiling & Buss, 2000).

Recent research has shown that a female's ovulation status may influence her mating strategy, a finding which suggests that the pursuit of EPC strategies may be a specialpurpose adaptive design for females (Thornhill & Gangestad, 2003). Penton-Voak and Perrett (1999) found that females' preferences for male facial attributes change as a function of their menstrual phase. When a female is in her most fertile phase, her preferences shift toward more masculinized faces. Similar results have also been found by Penton-Voak and Perrett (2000) and Johnston, Hagel, Franklin, Fink, and Crammer (2001). The authors interpret their findings as evidence for a conditional mate choice strategy whereby females in a high conception phase of their menstrual cycle exhibit a stronger preference for male facial cues that signal adaptive heritable genetic characteristics, such as immunocompetence. This shift for different mate preferences at ovulation coincides with an increase in females' self-reported arousal to sexual stimuli (Luschen & Pierce, 1972), peaks in sexual receptivity (Adams, Gold, & Burt, 1978), and an increased amount of attraction to and fantasy about men who are not their primary partners. It also coincides with an increase in females' extra-pair copulation frequency (Baker & Bellis, 1995) and an increase in mate guarding by a primary partner (Gangestad, Thornhill, & Garver, 2002), findings which suggest a sperm competition theory of double-mating behaviors.