ABSTRACT-Women prefer both the scent of symmetrical men and masculine male faces more during the fertile (late follicular and ovulatory) phases of their menstrual cycles than during their infertile (e.g., luteal) phases. Men's behavioral displays in social settings may convey signals that affect women's attraction to men even more strongly. This study examined shifts in women's preferences for these behavioral displays. A sample of 237 normally ovulating women viewed 36 or 40 videotaped men who were competing for a potential lunch date and then rated each man's attractiveness as a short-term and a long-term mate. As predicted, women's preference for men who displayed social presence and direct intrasexual competitiveness increased on high-fertility days relative to low-fertility days, but only in a short-term, not a long-term, mating context. These findings add to the growing literature indicating that women's mate preferences systematically vary across the reproductive cycle.Two recent lines of research have shown that the criteria women use to evaluate men's attractiveness shift across the menstrual cycle. First, women prefer the scent of men who evince high developmental stability (as measured by fluctuating asymmetry) particularly during fertile days of their cycles (Gangestad & Thornhill, 1998;Rikowski & Grammer, 1999;Thornhill & Gangestad, 1999b;Thornhill et al., 2003). Second, women prefer masculine faces more on fertile days than on nonfertile days (Johnston, Hagel, Franklin, Fink, & Grammer, 2001;Penton-Voak & Perrett, 2000;Penton-Voak et al., 1999). These findings are believed to reflect evolved adaptations for women to choose sires who can provide genetic benefits to offspring. Heightened attraction to men who possess putative indicators of genetic benefits (e.g., symmetry and facial masculinity, which covary positively; Gangestad & Thornhill, in press) may increase the probability that women have sex with them when fertile, even if such men are not their primary partners. This interpretation is supported by the finding that women's attraction to masculine facial features is heightened midcycle when they evaluate men as short-term partners (i.e., as sex partners), but not when they evaluate men as long-term, stable partners (PentonVoak et al., 1999). These preference shifts may explain why women report increased sexual attraction to men other than primary partners when fertile (Gangestad, Thornhill, & Garver, 2002).Although scent and facial attractiveness may importantly affect women's attraction to men (Buss & Schmitt, 1993;Herz & Cahill, 1997;Regan & Berscheid, 1995), men's behavior-how they interact with women and other men-may be even more important determinants of attraction. Women prefer men who display self-assurance and stand up for themselves with other men, but who exhibit warmth and agreeableness (e.g., Cunningham, Druen, & Barbee, 1997;Graziano, Jensen-Campbell, Todd, & Finch, 1997;Jensen-Campbell, Graziano, & West, 1995). The former attributes, which reflect intrasexual competitiveness, m...

Previous research has shown that women's mate preferences change across the ovulatory cycle in a number of ways. The leading explanation for these changes--the good genes hypothesis--predicts that women should prefer presumed markers of genetic benefits ("good genes") most strongly when they are fertile and evaluating men as possible short-term mates. Research testing this hypothesis has almost exclusively examined preferences for purported markers of good genes. Little is known about how preferences for men who display traits valued in long-term, investing mates (e.g., warmth and faithfulness) change across the cycle. The authors had women at different points in their ovulatory cycle rate videotapes of men in terms of how attractive they found each man as a short-term and long-term mate. The authors then examined how women's preferences for traits typically valued in long-term and/or short-term mates varied according to women's fertility status. The results supported the good genes hypothesis. Implications of these findings for models of human mating are discussed.

Preferences for mates that possess genes dissimilar to one's own at the major histocompatibility complex (MHC), a polymorphic group of loci associated with the immune system, have been found in mice, birds, fish, and humans. These preferences may help individuals choose genetically compatible mates and may adaptively function to prevent inbreeding or to increase heterozygosity and thereby immunocompetence of offspring. MHC-dissimilar mate preferences may influence the psychology of sexual attraction. We investigated whether MHC similarity among romantically involved couples (N= 48) predicted aspects of their sexual relationship. All women in our sample normally ovulated, and alleles at three MHC loci were typed for each person. As the proportion of MHC alleles couples shared increased, women's sexual responsivity to their partners decreased, their number of extrapair sexual partners increased, and their attraction to men other than their primary partners increased, particularly during the fertile phase of their cycles.

Normally ovulating women have been found to report greater sexual attraction to men other than their own partners when near ovulation relative to the luteal phase. One interpretation is that women possess adaptations to be attracted to men possessing (ancestral) markers of genetic fitness when near ovulation, which implies that women's interests should depend on qualities of her partner. In a sample of 54 couples, we found that women whose partners had high developmental instability (high fluctuating asymmetry) had greater attraction to men other than their partners, and less attraction to their own partners, when fertile.

In socially monogamous species in which males heavily invest in offspring, there arises an inevitable genetic conflict between partners over whether investing males become biological fathers of their partners' offspring. Humans are such a species. The ovulatory-shift hypothesis proposes that changes in women's mate preferences and sexual interests across the cycle are footprints of this conflict. When fertile (mid-cycle), women find masculine bodily and behavioral features particularly sexy and report increased attraction to men other than current partners. Men are more vigilant of partners when the latter are fertile, which may reflect evolved counteradaptations. This adaptationist hypothesis has already generated several fruitful research programs, but many questions remain.