In a recent investigation of sexual diversity among eight Makushi communities in Guyana, Schacht and Mulder (2015) asked dozens of people about their “sociosexuality” (i.e., the degree one is willing to have sex without commitment). They found in Makushi communities with extremely high sex ratios (where many more men than women exist), men’s sociosexuality was so low that it was nearly identical to women’s. Does this mean that men’s and women’s evolved sexual psychology is identical in adaptive design? No, not even close. Let me explain why.

It seems just about every year a new group of researchers asserts they have “debunked” some basic tenet of . A recurring claim is evolutionary explanations of human sex differences must be wrong if researchers are able to show women are at all interested in short-term mating, particularly when they seem just as interested as men are (Schacht & Mulder, 2015). In truth, finding women are acutely interested in short-term mating is entirely unsurprising to evolutionary psychologists. In fact, they have been predicting and confirming women’s short-term mating tendencies for decades.

It is simply untrue that evolutionary psychologists expect all women are solely monogamous and all men are entirely promiscuous, or that researchers should expect humans comport to a “coy females and ardent males” stereotype (Schacht & Mulder, 2015, p. 1). When scientists make such a misguided claim about evolutionary psychology they are engaging in a Straw Man argument. In short, they are setting up a false portrayal of evolutionary psychological science. Although I have written about this before (see http://www.psychologytoday.com/blog/sexual-personalities/201202/men-women-and-interplanetary-promiscuity ), let me revisit two fundamental reasons why this is clearly a Straw Man argument.

First, more than 20 years of empirical evidence has been accumulated by evolutionary psychologists confirming that women are, in all likelihood, “specially-designed” for short-term mating. That women possess highly evolved short-term mating strategies has been a foundational feature of evolutionary psychology since the early 1990s (Buss & Schmitt, 1993*; Kenrick et al., 1990), and several programs of research, many supported by literally dozens of studies, strongly support this assertion.

Historically, evolutionary psychologists were among the first psychologists to treat women’s short-term mating as an adaptive reproductive strategy (most other psychologists did, and still do, treat short-term mating as entirely dysfunctional or pathological, a failure to "bond" with your one true love; I call it the Disney-fication of women’s by majority of sex researchers who follow the Standard Social Science Model).

What evidence is there that evolutionary psychologists expected women to be designed for short-term mating? Some of the earliest studies by evolutionary psychologists on women’s adaptive desires for short-term mating include:

Buss, D. M. & Schmitt, D. P. (1993). Sexual strategies theory: An evolutionary perspective on human mating. Psychological Review, 100, 204–232.

Kenrick, D. T., Groth, G. E., Trost, M. R., & Sadalla, E. K. (1993). Integrating evolutionary and social exchange perspectives on relationships: Effects of , self-appraisal, and involvement level on mate selection criteria. Journal of and Social Psychology, 64, 951–969.

Kenrick, D. T., Sadalla, E. K., Groth, G., & Trost, M. R. (1990). Evolution, traits, and the stages of human courtship: Qualifying the parental investment model. Journal of Personality, 58, 97–116.

Scheib, J.E. (1994). Sperm donor selection and the psychology of female mate choice. Ethology & Sociobiology, 15, 113-129.

Seal, D.W., Agostinelli, G. & Hannett, C.A. (1994). Extradyadic romantic involvement: Moderating effects of sociosexuality and gender. Sex Roles, 31, 1–22.

Simpson, J. A., & Gangestad, S. W. (1992). Sociosexuality and romantic partner choice. Journal of Personality, 60, 31–51.

And evolutionary psychologists kept digging into the special psychology of women’s short-term mating desires in the late 90s:

Regan, P. C. (1998). Minimum mate selection standards as a function of perceived mate value, relationship context, and gender. Journal of Psychology and Human Sexuality, 10, 53–73.

Regan, P. C. (1998). What if you can’t get what you want? Willingness to compromise ideal mate selection standards as a function of sex, mate value, and relationship context. Personality and Social Psychology Bulletin, 24, 1294–1303.

Regan, P. C., & Berscheid, E. (1997). Gender differences in characteristics desired in a potential sexual and partner. Journal of Psychology and Human Sexuality, 9, 25–37.

Simpson, J. A., Gangestad, S. W., Christensen, P., Niels, K. (1999). Fluctuating asymmetry, sociosexuality, and intrasexual competitive tactics. Journal of Personality and Social Psychology, 76, 159-172.

Wiederman, M. W., & Dubois, S. L. (1998). Evolution and sex differences in preferences for short-term mates: Results from a policy capturing study. Evolution and Human Behavior, 19, 153–170.

And into the early 2000s, some of the studies included:

Gangestad, S. W., & Simpson, J. A. (2000). The evolution of human mating: Trade-offs and strategic pluralism. Behavioral and Brain Sciences, 23, 573-587.

Grammer, K., Renninger, L. and Fischer, B. (2004). Disco clothing, female sexual , and relationship status: Is she dressed to impress? Journal of Sex Research, 41, 66–74.

Greiling, H. and Buss, D. M. (2000). Women’s sexual strategies: The hidden dimension of short-term mating. Personality and Individual Differences, 28, 929–963.

Little, A.C., Jones, B.C., Penton-Voak, I.S., Burt, D.M., & Perrett, D.I. (2002). Partnership status and the temporal context of relationships influence human female preferences for sexual dimorphism in male face shape. Proceedings of the Royal Society of London B, 269, 1095-1103.

Pawlowski, B., & Jasienska, G. (2005). Women’s preferences for sexual dimorphism in height depend on menstrual cycle phase and expected duration of relationship. Biological Psychology, 70, 38-43.

Penton-Voak, I. S., Little, A. C., Jones, B. C., Burt, D. M., Tiddeman, B. P., Perrett, D. I. (2003): Female condition influences preferences for sexual dimorphism in faces of male humans (Homo sapiens). Journal of Comparative Psychology, 117, 264–271.

Regan, P.C., Levin, L., Sprecher, S., Christopher, F. S., & Cate, R. (2000). Partner preferences: What characteristics do men and women desire in their short-term and long-term romantic partners? Journal of Psychology and Human Sexuality, 12, 1–21.

Regan, P.C., Medina, R., & Joshi, A. (2001). Partner preferences among men and women: What is desirable in a sex partner is not necessarily desirable in a romantic partner. Social Behavior and Personality, 29, 625-633.

Schmitt, D. P., Couden, A., & Baker, M. (2001). Sex, temporal context, and romantic desire: An experimental evaluation of Sexual Strategies Theory. Personality and Social Psychology Bulletin, 27, 833–847.

Scheib, J.E. (2001). Context-specific mate choice criteria: Women's trade-offs in the contexts of long-term and extra-pair mateships. Personal Relationships, 8, 371-389.

Shackelford, T. K., Weekes, V. A., LeBlanc, G. J., Bleske, A. L., Euler, H. A., & Hoier, S. (2000). Female coital and male . Human Nature, 11, 299-306.

Stewart, S., Stinnett, H., & Rosenfeld, L. B. (2000). Sex differences in desired characteristics of short-term and long-term relationship partners. Journal of Social and Personal Relationships, 17, 843–853.

Thornhill, R., & Gangestad, S. W. (2003). Do women have evolved adaptation for extra-pair copulation? In Evolutionary aesthetics (pp. 341-368). Springer Berlin Heidelberg.

Then into the late 2000s:

Haselton, M. G. & Miller, G. F. (2006). Women’s fertility across the cycle increases the short-term attractiveness of creative . Human Nature, 17, 50–73.

Li, N. (2007). Mate preference necessities in long- and short-term mating: People prioritize in themselves what their mates prioritize in them. Acta Psychologica Sinica, 39, 528-535.

Li, N. P., & Kenrick, D. T. (2006). Sex similarities and differences in preferences for short-term mates: What, whether, and why. Journal of Personality and Social Psychology, 90, 468–489.

Pillsworth, E. G., & Haselton, M. G. (2006). Male sexual attractiveness predicts differential ovulatory shifts in female extra-pair and male mate retention. Evolution & Human Behavior, 27, 247–258.

Pipitone, R. N., & Gallup Jr, G. G. (2008). Women's voice attractiveness varies across the menstrual cycle. Evolution and Human Behavior, 29, 268-274.

Provost, M.P., Kormos, C., Kosakoski, G., & Quinsey, V.L. (2006). Sociosexuality in women and preference for facial masculinization and somatotype in men. Archives of Sexual Behavior, 35, 305-312.

Provost, M.P., Troje, N.F.,& Quinsey, V.L. (2008). Short-term mating strategies and attraction to masculinity in point-light walkers. Evolution and Human Behavior, 29, 65-69.

Puts, D. A. (2006). Cyclic variation in women’s preferences for masculine traits: Potential causes. Human Nature, 17, 114–127.

Thornhill, R., & Gangestad, S. W. (2008). The evolutionary biology of human female sexuality. New York: Oxford University Press.

Heck, it is still going on right now. These evolutionary psychologists cannot seem to leave women’s short-term mating psychology alone. It is like they are obsessed:

DeBruine, L. M. (2014). Women’s preferences for male facial features. In Evolutionary Perspectives on Human Sexual Psychology and Behavior (pp. 261-275). Springer New York.

Gangestad, S. W., Garver-Apgar, C. E., Cousins, A. J., & Thornhill, R. (in press). Intersexual conflict across women's ovulatory cycle. Evolution and Human Behavior.

Gangestad, S. W., Thornhill, R., & Garver-Apgar, C. E. (2010). Fertility in the cycle predicts women's interest in sexual opportunism. Evolution and Human Behavior, 31, 400-411.

Gildersleeve, K., Haselton, M. G., & Fales, M. R. (2014). Do women's mate preferences change across the ovulatory cycle? A meta-analytic review. Psychological Bulletin, 140, 1205-1259.

Gildersleeve, K., Haselton, M. G., & Fales, M. R. (in press). Meta-analyses and p-curves support robust cycle shifts in women’s mate preferences: Reply to Wood and Carden (2014) and Harris, Pashler, and Mickes (2014).

Hughes, S.M., Farley, S.D., & Rhodes, B.C. (2010). Vocal and physiological changes in response to the physical attractiveness of conversational partners. Journal of Nonverbal Behavior, 34, 155–167.

Larson, C.M., Pillsworth, E.G., Haselton, M.G. (2012). Ovulatory shifts in women’s attractions to primary partners and other men: Further evidence of the importance of primary partner sexual attractiveness. PLoS ONE, 7, e44456. doi:10.1371/journal.pone.0044456.

Quist, M.C., Watkins, C.D., Smith, F.G., Little, A.C., DeBruine, L.M., Jones, B.C. (2012). Sociosexuality predicts women's preferences for symmetry in men's faces. Archives of Sexual Behavior, 41, 1415-1421.

Sacco, D.F., Jones, B.C., DeBruine, L.M., Hugenberg, K. (2012). The roles of sociosexual orientation and relationship status in women’s face preferences. Personality and Individual Differences, 53, 1044-1047.

Schmitt, D.P., Jonason, P.K., Byerley, G.J., Flores, S.D., Illbeck, B.E., O‘Leary, K.N., & Qudrat, A. (2012). A reexamination of sex differences in sexuality: New studies reveal old truths? Current Directions in Psychological Science, 21, 135-139.

It is utterly astounding that any researcher at all familiar with modern psychological science would claim today that evolutionary psychologists believe all women are designed to be monogamous, whereas all men are designed to be promiscuous. Such a claim by a scientist is, quite frankly, intellectual flim-flamming. And it needs to stop.

The second critical reason why documenting women’s interest in short-term mating does not debunk evolution’s relevance to human sexuality is that, although women are designed for short-term mating, per se, the psychological “special design” of women's short-term mating strategy (e.g., heightened preferences for masculinity and bodily symmetry) is different from the special design of men's short-term mating strategy (e.g., generally relaxed mate preferences and indiscriminately desiring large numbers of partners). In short, women and men do not want pursue short-term mating in the same way, nor do they desire identical attributes in potential short-term mates.

Women are extremely sexual beings, for sure, and short-term mating is a part of their strategic repertoire according to evolutionary psychologists. Indeed, in some ways women appear more specially-designed for short-term sex than men are. But when pursuing a short-term mating strategy, women tend to desire high quality over high quantity (Thornhill & Gangestad, 2008). In contrast, men tend to be less insistent on high quality when short-term mating (on average, there are important intrasexual variations, too; Gangestad & Simpson, 2000).

What evidence is there of these differences in short-term mating design? Quite a bit (for a review, see Schmitt, 2014).

Schmitt, D.P. (2014). Evaluating evidence of mate preference adaptations: How do we really know what Homo sapiens sapiens really want? In Weekes-Shackelford, V.A., & Shackelford, T.K. (Eds.), Evolutionary perspectives on human sexual psychology and behavior (pp. 3-39). New York: Springer.

Perhaps the most convincing evidence for sex differences in the special design of short-term mating psychology comes from studies looking at sex differences in attitudes and behaviors involving opportunistic, low cost, or anonymous sex. Nearly all point in the direction of men, on average, having more desires for opportunistic, low cost, or anonymous casual sex than women do. Results in support of this view (along with some sample references) include this sample of 20 empirical findings:

1. Men are more likely than women to engage in extradyadic sex (Atkins et al. 2001; Glass & Wright 1985; Oliver & Hyde 1993; Petersen & Hyde 2010; Thompson 1983; Wiederman 1997)

2. Men are more likely than women to be sexually unfaithful multiple times with different sexual partners (Blumstein & Schwartz 1983; Brand et al. 2007; Hansen 1987; Laumann et al. 1994; Lawson & Samson 1988; Spanier & Margolis 1983)

3. Men are more likely than women to seek short-term sex partners that are already married (Davies et al. 2007; Jonason et al. 2009; Parker & Burkley 2009; Schmitt et al. 2004; Schmitt & Buss 2001)

4. Men are more likely than women to have involving short-term sex and multiple opposite-sex partners (Ehrlichman & Eichenstein 1992; Ellis & Symons 1990; Jones & Barlow 1990; Leitenberg & Henning 1995; Rokach 1990)

5. Men are more likely than women to pay for short-term sex with (male or female) prostitutes (Burley & Symanski 1981; Mitchell & Latimer 2009; Symons 1979)

6. Men are more likely than women to enjoy sexual magazines and videos containing themes of short-term sex and sex with multiple partners (Hald 2006; Koukounas & McCabe 1997; Malamuth 1996; Murnen & Stockton 1997; Salmon & Symons 2001; Youn 2006)

7. Men are more likely than women to desire, have, and reproductively benefit from multiple mates and spouses (Bereczkei & Csanaky 1996; Betzig 1986; Jokela et al. 2010; Perusse 1993; Stone et al. 2005; Zerjal et al. 2003)

8. Men desire larger numbers of sex partners than women do over brief periods of time (Fenigstein & Preston 2007; McBurney et al. 2005; Njus & Bane 2009; Rowatt & Schmitt 2003; Schmitt et al. 2003; Wilcox 2003)

9. Men are more likely than women to seek one-night stands (Herold & Mewhinney 1993; Spanier & Margolis 1983)

10. Men are quicker than women to consent to having sex after a brief period of time (Cohen & Shotland 1996; McCabe 1987; Njus & Bane 2009; Rowatt & Schmitt 2003; Schmitt et al. 2003)

11. Men are more likely than women to consent to sex with a stranger (Clark 1990; Clark & Hatfield 1989; Greitemeyer 2005; Hald & Høgh-Olesen 2010; Schützwohl et al. 2009; Voracek et al. 2005; Voracek et al. 2006)

In 1989, Clark and Hatfield had experimental confederates approach college students across various campuses and ask if they would like to have sex. Around 75% of men agreed to have sex with a complete stranger, whereas no women (0%) agreed to sex with a complete stranger. Given that about 50% of men in college are "in a relationship" at any given time, this might imply a lot of men walk around pretty much ready to go, even if they are in a relationship.

Twenty years later, Hald and Høgh-Olesen (2010) largely replicated these findings in Denmark, with 59% of single men and 0% of single women agreeing to the proposition, “Would you go to bed with me?”

12. Men are more likely than women to want, initiate, and enjoy a variety of sex practices (Baumeister et al. 2001; Laumann et al. 1994; Purnine et al. 1994)

13. Men have more positive attitudes than women toward casual sex and short-term mating (Hendrick et al. 1985; Laumann et al. 1994; Oliver & Hyde 1993; Petersen & Hyde 2010)

14. Men are less likely than women to regret short-term sex or “hook-ups” (Bradshaw et al. 2010; Campbell 2008; de Graaf & Sandfort 2004; Paul & Hayes 2002; Roese et al. 2006; Townsend et al. 1995)

15. Men succumb to sexual temptations more than women because they have more sexual impulses than women do, not because women have better sexual (Tidwell & Eastwick, 2013).

Tidwell, N. D., & Eastwick, P. W. (2013). Sex Differences in Succumbing to Sexual Temptations a Function of Impulse or Control? Personality and Social Psychology Bulletin, 0146167213499614...

16. Men have more unrestricted sociosexual attitudes and behaviors than women (Clark 2006; Lippa 2009; Schmitt 2005a; Schmitt et al. 2001; Simpson et al. 2004; Simpson & Gangestad, 1991)

17. Men generally relax mate preferences (whereas women increase selectivity for physical attractiveness) in short-term mating contexts (Kenrick et al. 1990; Kenrick et al. 1993; Li et al. 2002; Li and Kenrick 2006; Regan 1998a, 1998b; Regan & Berscheid, 1997; Regan et al., 2000; Simpson & Gangestad, 1992; Stewart et al., 2000; Wiederman & Dubois, 1998)

18. Men perceive more sexual interest from strangers than women (Abbey 1982; Haselton & Buss 2000; Henningsen et al. 2006; Sigal et al. 1988)

19. Gay men much more likely to have extra-pair sex then lesbians

Blumstein and Schwartz (1983) studied 6,071 long-term established couples (married/cohabiting, gays and lesbians included) found these sex differences: In response the question…ever have an affair?

Heterosexual Husbands (12% said yes) > Heterosexual Wives (7% said yes)

Gays (76% said yes) > Lesbians (11% said yes)

20. Men have higher general sex drive than women across almost all measures and all studied cultures, with a culture’s size of sex differences in sex drive being unrelated to sociopolitical gender equity

(Baumeister, Catanese, & Vohs, 2001; Lippa, 2009)

It is true that there are cultural variations and gendered contextual influences on many aspects of short-term mating desires (e.g., see Schmitt, 2005 on sociosexuality varying across 48 nations), but sex differences in casual sex desires typically vary from medium to large across cultures, the differences almost never completely disappear. Historically and cross-culturally one can sometimes come across exceptions, such as the Shakers religion not allowing any physical contact between men and women, hence no sex differences in casual sex behavior there.

Schacht and Mulder (2015), as noted earlier, found across eight Makushi communities in Guyana that in populations with extremely high sex ratios (in one there were 1.43 men for every 1 woman, a very high ratio), men’s sociosexuality was so low that it was nearly identical to women’s. The raw data are available from this study [doi:10.5061/dryad.587v1], and the sample sizes are quite small yielding very low power for detecting significant differences within communities (the average community sample was just short of 38 people).

Nevertheless, based on these data it does appear in the highest sex ratio community that women’s average sociosexuality (M = 27.2, SD = 12.9) just as high as men’s (M = 26.6, SD = 13.5), a small effect size (d = -0.05). In the community with the second highest sex ratio (1.33 men per woman), women’s average sociosexuality (M = 23.5, SD = 8.7) was not as high as men’s (M = 30.7, SD = 24.1), a moderately-sized difference, d = 0.45. Whereas in the community with the lowest sex ratio (0.93 men per woman), women’s average sociosexuality (M = 25.2, SD = 16.3) was not even close to as high as men’s (M = 54.3, SD = 37.7), a very large sex difference of d = 1.08. When looking only at single people across these three communities, the sex differences shift to become much larger (d = 0.66, d = 0.92, and d = 2.56, respectively).





As the Schacht and Mulder (2015) note, others have found similar apparent suppression of men’s sociosexuality when women are so rare they are able to insist men must engage in long-term mating in order to have sex (Schmitt, 2005). Of course, it is worth noting that when men are the scarcer sex, they do not insist that women engage in long-term mating in order to have sex. Unless one wanted to argue men are suppressing their own sociosexuality in high sex ratio cultures, the population-varying sex differences actually reveal a fundamental difference in men’s and women’s preferred mating strategies. When women are scarce and have the greater dyadic power, a culture of long-term mating ensues. Do sex differences in all aspects of sociosexuality completely disappear? Likely not. Not in desires and attitudes, and likely not among those who are single, as noted above.

Another example of an evolved sex difference not always manifesting itself across all cultures is the sex difference in physical height. Among cultures in high altitude ecologies, the sex difference is minimized and sometimes nearly absent as shorter body frames provide for much better survival (Gaulin, 1992; Gaulin & Sailer, 1983). Among most ecologies, though, sex differences in height are readily seen, and even manifest as the largest in nations that have the most sociopolitical gender equality (such as in Scandinavian nations; for fuller discussion of these issues, see Schmitt, 2014).

The key with contextualizing historical and cross-cultural analyses is to consider the hyperspace of all possible cultural forms and determine whether there are detectable patterns across real human cultures that deviate from this potential hyperspace of cultures (past, present, foraging, modern, and so forth; Cronk, 1999). Existing evidence suggests strong and patterned deviations from random sexual desire differences between men and women when it comes to short-term mating.

Most importantly, cultural exceptions, when found, do not obviate our need to explain these generally vast and enduring patterns of sex differences. Instead, it leads us to consider what other adaptations (e.g., ) are overwhelming or interacting with evolved sex differences, including whether certain sexual adaptations are specially-designed to be facultatively responsive to local ecological circumstances, such as local pathogen levels or sex ratios (see Schmitt, 2005). Cultural exceptions to sex differences often implicate more evolutionary psychology is needed to explain extant findings, not less. And please, enough with the Straw Men!

*contact the author for details on specific references (see also, Buss & Schmitt, 2011).

Buss, D.M., & Schmitt, D.P. (2011). Evolutionary psychology and feminism. Sex Roles, 64, 768-787.

Schacht, R., & Mulder, M. B. (2015). Sex ratio effects on reproductive strategies in humans. Royal Society Open Science, 2, 140402.