Male Counter Strategies to Cyclic Shifts
Women’s mating psychology, behavior, and attractiveness shift over their menstrual cycle. Men may have evolved strategies to mitigate any undesirable effects of these shifts on their own fitness.
Human female fertility varies over the menstrual cycle. The likelihood that a single act of intercourse will result in conception is greatest in the days preceding ovulation. At this time, women are more attractive and are more driven to enhance their attractiveness. Androphilic women become more interested in men who are not their primary partner, and their preference for physically and behaviorally feminine men decreases. Because men who are women’s primary partners risk desertion or (if their partner engages in short-term sexual relationships with other men) investing in biologically unrelated offspring, they have likely experienced selection pressure to deploy counterstrategies that mitigate the effects of female menstrual cycle shifts. These counterstrategies may include changes to a man’s sexual desire, his jealousy and mate-guarding behavior, and his propensity to compete with sexual rivals.
Men may respond to female shifts in sexual behavior or appearance by increasing sexual interest in primary partners who are in the fertile cycle phase. Cerda-Molina et al. (2013) collected female underarm and vulvar odor samples while the women were in the periovulatory (fertile) and luteal (non fertile) phases of their cycle. Men sniffed the samples and completed a questionnaire on their interest in sex. Men’s sex interest increased after they smelled periovulatory samples but did not change after they smelled luteal samples. Other studies indicate that exposure to the body odor of women in the fertile phase results in men estimating women’s sexual arousal as higher and that men are more prone to behaviorally mimic a woman in the fertile phase (Miller and Maner 2011). Increased desire and an overestimation of women’s sexual interest may cause men to more readily and more frequently initiate sex, thereby reducing the primary partner’s interest in extrapair copulations, limiting her opportunities for extrapair copulations, or instigating sperm competition with her extrapair sexual partners.
Miller and Maner (2010) hypothesized that men’s responses to cues of fertility in non-primary partners should vary depending on whether the man is in a current relationship. They showed that single men are more attracted to fertile than non-fertile women but that partnered men are less attracted to fertile women. Devaluing a fertile non-partner may reduce men’s temptation to stray from their primary partner and promote relationship stability.
Jealousy and Mate Retention Behavior
Because men stand to lose more if their female partner copulates with other men during her fertile rather than her non-fertile phase, men may be expected to feel greater sexual jealousy and to behave in ways that minimize the likelihood of a partner straying or being poached when that partner is most fertile. Gangestad et al. (2002) had women rate the extent to which their male primary partner performed each of 41 mate retention behaviors. They found that women reported that their partner performed more of such behaviors when they were fertile, and behaviors were more frequent the nearer women were to ovulation. Proximity to ovulation was related to men’s proprietariness and attentiveness, but the strongest relationship was with vigilance (checking up on the partner’s location and activities). Less attractive women report that their partner is more jealous and possessive near ovulation, whereas more attractive women report consistently high jealousy and possessiveness throughout the cycle (Haselton and Gangestad 2006). Mate retention behavior also encompasses tactics that are perceived positively, and women whose primary male partner is lower in sexual attractiveness report that their partner more frequently expresses love and commitment during the high rather than the low fertility cycle phase (Pillsworth and Haselton 2006).
The Challenge Hypothesis
The challenge hypothesis posits that men may compete more strongly with male sexual rivals when in the presence of fertile females. Testosterone is implicated in sex drive and competitiveness, and research suggests that salivary testosterone levels increase in men exposed to the body odor of fertile women and decrease after exposure to the body odor of women in the non-fertile phase (Cerda-Molina et al. 2013). Similarly, the testosterone levels of men whose primary partners are in the fertile phase of their cycle increase after men view photographs and descriptions of rivals but only if those rivals are competitive and attractive: men whose partners were in the non-fertile phase, or who viewed uncompetitive rivals, did not experience an increase in testosterone (Fales et al. 2014).
Men may have benefited historically by an increased sensitivity to rivals at times when the threat of partner infidelity was greatest. Women are more attracted to men with masculine and dominant traits during the fertile phase of their cycle. Men whose primary partners are in the fertile phase rate male faces as more dominant than men whose partners are in the non-fertile phase but only if those faces appear especially dominant: men do not rate submissive faces differently as a function of their partner’s cycle phase (Burriss and Little 2006). This shift in perception may aid men in identifying rivals who present the greatest threat to their relationship.
Women can only accrue the putative genetic benefits of copulating with extrapair men if copulation occurs when fertility is most likely, in the days preceding ovulation. Because women’s extrapair sexual behavior is detrimental to the fitness of their male primary partner, it is plausible that men would have evolved counterstrategies to prevent their partner straying or being poached. Research suggests that men are more sexually interested in fertile women, are more apt to be jealous of fertile partners, and respond hormonally and behaviorally toward threatening rivals when their partner is fertile. If a cost to men of deploying these counterstrategies is the increased likelihood of a partner’s desertion, it would be maladaptive to do so uniformly across the partner’s cycle.
A limitation of much of the research on this topic is that it relies upon women’s reports of men’s behavior. It is possible that, just as women’s mating psychology shifts over the cycle, so too does their perception of their partner’s counterstrategies. Certainly, women resist male mate-guarding more strongly when fertile (Gangestad et al. 2014). Their reports of partner mate retention behavior may, therefore, not be accurate. Also, most research on responses to women’s cyclic shifts is laboratory-based and tests unrelated individuals. There is a need for more research on how men respond to cyclic shifts and on how their female partners resist counterstrategies, in real relationships (Haselton and Gildersleeve 2015).
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