A serious dose of criticism, both of one's own views and the views of others, is welcome medicine in good sexual science. It's important that we're skeptical of theories and hypotheses, that we relentlessly scrutinize research methods and interpretations of data. Healthy sexual science welcomes and thrives on legitimate critiques. To paraphrase Jack Nicholson in As Good As It Gets, critics make one want to be a better sexologist.
Recently, though, critics of an approach to human sexual diversity called "evolutionary psychology" have been offering up some rather unmerited denigrations of the field. They've been manufacturing critiques of Straw Man positions that evolutionary psychologists don't actually hold, and they've been ignoring masses of evidence that evolutionary psychologists have generated. For example, many critics keep portraying evolutionists as "Mars-Venus" essentialists, characterizing predictions about sex differences in sexuality as logically implying that the natural world is an all-males-are-promiscuous and all-females-are-monogamous kind of place (see). I wish these critics would stop engaging in crude stereotyping of evolutionary psychology in this way. Writing this rubbish is poor science, poor science writing, and it is demonstrably not what evolutionary psychology is about. Here is why.
Across the animal kingdom, it is very clearly not the case that males are always eagerly promiscuous and females are always choosy monogamists. As Robert Trivers (1972) pointed out some 40 years ago, which gender is choosier depends on a host of parental investment factors and sexual selection processes, and sometimes males are the choosier gender in a species (e.g., Mormon crickets, katydids, etc.). More than that, other features can affect sexual selection (e.g., local mortality, population density, etc.) and further influence gendered choosiness, so any kind of categorical, essentialist Mars-Venus distinction is hardly the right way to conceptualize animal sexualities. Evolutionary psychologists not only know this, they have been arguing this for decades (Kenrick et al., 1990; Symons, 1979).
That said, the fact that humans are mammals (with heavy obligatory investments of gestation in women) and because humans possess certain revealing patterns of sexually-selected attributes (e.g., men are larger, stronger, physically mature later, take greater risks, die much earlier, the list goes on), from a cross-species perspective is it likely that men probably possess design features that motivate them to seek and consent to indiscriminate sex more than women. Not a Mars-Venus type of gender divide mind you (with all men always promiscuous and all women always monogamous). Evolutionary scientists only expect men will, on average, seek and consent to casual sexual encounters more than women will. As all careful scientists acknowledge, evolved sex differences are rarely a simple manifestation of essential categories. Most evolved sex differences arise instead from degrees of hormone-related organizational effects on the brain, activational effects during adulthood, and sometimes direct genetic effects (McCarthy & Ball, 2011). Sex differences also undoubtedly result from processes of socialization and sex roles that are, themselves, derived products of our evolved biology (see Mealey, 2000; Wood & Eagly, 2007). Even though gendered sexual development is quite complicated, this doesn't nullify the ability of evolutionary psychologists to make accurate predictions about average-level behavioral sex differences in sexuality. And some of these sex differences are going to be remarkably robust (see).
OK, this part is important and many critics seem unable to understand it, so I'll repeat. The Trivers-based sex difference explanation often proffered by evolutionary psychologists does not expect that all men will always be eagerly seeking promiscuous sex, nor does it imply that all women always eschew causal mating opportunities. Just as not all men are taller than all women (and yet men are taller than women, on average), men are expected by evolutionary psychologists to be more eager than women for indiscriminate casual sex, but only on average. Factors such as a man's culture (including his religion...members of the Shakers religious sect don't have sex at all––no sex differences in promiscuity there!), his family history (unpredictable early childhood experiences tend to elicit more short-term mating; Simpson et al., in press), his phenotypic masculinity, his facial symmetry, his mate value, his testosterone level, his oxytocin receptor gene variants, his dopamine D4 receptor gene variants, and a host of other associative features likely impact his desire, ability, and general tendency to strategically pursue indiscriminate sex (see). Biological and social contexts matter for reproductive strategies in most species, this is certainly no less true for humans (yes, even male humans).
Evolutionary psychologists have been blazing trails in terms of researching the special contexts that matter most when it comes to casual sex in humans. Unfortunately, an especially troubling tendency among these Mars-Venus Straw Man propagators is that they either ignore or are entirely unfamiliar with the vast amount of evolutionary psychology research accumulated over the last 20 years. Let me provide some background.
Beginning in the early 1990s, much of the emphasis in evolutionary psychology theory and research turned to explaining sexuality differences within genders. The early work of David Buss, Doug Kenrick, Steve Gangestad, Jeff Simpson, and many others documented that women and men BOTH are designed for short-term mating (i.e., casual sex, brief affairs, one-night stands; Kenrick et al., 1990). What women and men want in their short-term mates, how they pursue them, the benefits they gain, all of these things are different from when the sexes strategically pursue long-term mates. In this view, all humans possess specialized adaptive designs for both brief sexual encounters and enduring romantic partnerships. Temporal context matters, and evolutionary psychologists were the first to point this out.
Crucially, the adaptive design of women's and men's short-term strategies is in many ways psychologically distinct (Jonason & Buss, 2012). Women can especially benefit in short-term mating from things like access to high quality genes (genes from men they couldn't access as long-term mates), access to protection and provisioning for herself and her offspring (such as in partible paternity cultures), using short-term mating to achieve long-term mating goals, and many other functions. Predictably, women who actively pursue short-term mating strategies tend to be somewhat choosy about the mate value qualities of their brief sexual partners, preferring to mate with men who are physically symmetrical, possess facial masculinity, and give off other cues to high testosterone levels (see Gangestad & Simpson, 2000).
