Female who is intimate with someone other than her partner.
Human mating is socially monogamous, where males and females create long-term pair bonds that share space, resources, and responsibilities for raising offspring. Not all such relationships are sexually monogamous, however, because significant proportions of males and females engage in extra-pair copulations. Extra-pair copulations are observed across various fish, bird, mammal, and insect species (Birkhead 2000). In humans, data from the most recent General Social Survey showed that 20% of men and 13% of women report having sex with someone who is not their partner (Wang 2018). Prevalence rates vary across location, sampling, and measurement methods, with some studies reporting female infidelity rates up to 25% (Whisman and Snyder 2007).
Theoretical explanations for the relatively high prevalence rates of female infidelity address its possible functions. Unlike men, women cannot increase offspring number through increasing mate number, but extra-pair copulations may increase female fitness by mating with males with better genes, gaining additional resources, confusing paternity to improve offspring safety, enhancing status, diversifying genes, increasing social networks for employment, or replacing a low-quality mate (reviewed in Mulder and Rauch 2009; Wilson and Daly 1992).
There are two potential factors that increase the risk of female infidelity: female mate value and the amount of time the couple spends apart (Stieglitz et al. 2012). A female’s mate value is typically determined by age and her ability to reproduce successfully. Younger females are more likely than older females to be reproductively successful and have higher reproductive value, which makes the potential loss of a younger wife more costly to males. Consistent with this view, Stieglitz et al. (2012) found that women reported their partner experienced more jealousy under these conditions.
Female infidelity may also be costly because of the risks associated with partner jealousy, including relationship conflict, intimate partner violence, and in some cases, homicide (see “Partner Abuse and Homicide” entry). It appears as though men are more jealous in response to sexual infidelity (i.e., when a partner engages in an extra-pair copulation) than emotional infidelity (i.e., when a partner spends time and resources with someone outside their relationship), since sexual infidelity may result in cuckoldry, which incurs a cost to men. Various sexually coercive behaviors, such as intimate partner sexual and physical violence, may have evolved to prevent or minimize the risk of cuckoldry (Camilleri and Quinsey 2012; Goetz and Shackelford 2006; see “Sperm Competition and Partner Abuse” entry). Considering infidelity is risky and even dangerous, females put great effort in attempt to evade their partner during extra-pair copulation.
Men appear to respond to both direct cues to cuckoldry risk (i.e., by partner’s actions that are indicative of infidelity) and indirect cues to cuckoldry risk (i.e., proportion of time spent away from a partner since last having intercourse), where more salient and recent cues are associated with either a greater propensity to engage in either sexual coaxing or sexual coercion (Camilleri and Quinsey 2009).
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- Camilleri, J. A., & Quinsey, V. L. (2012). Sexual conflict and partner rape. In A. T. Goetz & T. K. Shackelford (Eds.), Oxford handbook of sexual conflict in humans (pp. 257–268). New York: Oxford University Press.Google Scholar
- Wang, W. (2018). Who cheats more? The demographics of infidelity in America. Retrieved 26 July 2018, from https://ifstudies.org/blog/who-cheats-more-the-demographics-of-cheating-in-america.
- Wilson, M., & Daly, M. (1992). The man who mistook his wife for a chattel. In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture (pp. 289–322). New York: Oxford University Press.Google Scholar