Sexual Strategies Theory
David M. Buss1 and David P. Schmitt2 1The University of Texas at Austin, Austin, TX, USA 2Bradley University, Peoria, USA
Intersexual relations; Mating strategies
Sexual strategies theory (SST) is a middle-level evolutionary theory of mating strategies that both males and females adopt under different circum- stances. It differs from previous theories in that it includes multiple motives each individual can have, such as short-term versus long-term mating, as well as when and why different motives would be predominant.
Sexual strategies theory (SST) posits that humans have evolved a complex menu of mating strate- gies, that some of these mating adaptations are tethered to the temporal dimension of mating, and that although some mating adaptations are similar in women and men, some differ
profoundly between the sexes (Buss and Schmitt 1993). Before describing the major premises, pre- dictions, and empirical tests of SST, it is useful to briefly describe theories of mating prior to its articulation.
Previous theories typically posited singular mating motives, such as a quest for similarity, a search for complementarity, or the desire for equity. These theories had five major limitations that SST sought to rectify: (1) each posited a single mating motive, rendering them extremely simplistic; (2) all failed to explain why humans would be motivated by the singular drives; (3) all failed to specify the domains or contexts in which people sought similarity, complementarity, or equity, a degree of generality that precluded any domain-specific predictions; (4) all assumed that mating psychology was identical for men and women, precluding any sex-differentiated predic- tions; and (5) none specified functions, the adap- tive problems solved by its central mating motive, thus divorcing mating psychology from any evo- lutionary anchoring. SST sought to rectify these limitations.
Nothing is closer to the central engine of the evolutionary process – differential reproductive success – than mating. Those who fail to select and attract a mate fail to become ancestors. To an evolutionary psychologist, it would defy scientific logic if evolution by selection had failed to forge a powerful set of adaptations surrounding mate selection, as it has in all known sexually reproducing species. SST posits, therefore, that
# Springer International Publishing AG 2016 T.K. Shackelford, V.A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science, DOI 10.1007/978-3-319-16999-6_1861-1
whatever mating motives humans have exist because they solved adaptive problems that con- tributed directly or indirectly to successful repro- duction over the long course of human evolutionary history.
The Two Major Axes of Sexual Strategies Theory
The two major axes of SST are temporal duration of mating (ranging from short-term casual sexual encounters to long-term committed mating rela- tions) and biological sex (male, female). Biological sex is critical because humans differ in their funda- mental reproductive biology. One difference is that fertilization occurs internally within women, not within men. A second difference is that women require a heavy 9-month investment of pregnancy to produce a single child; men can produce that same child with as little as one act of sexual inter- course. And there are other key differences – women’s fertility is cyclical, whereas men’s fertility is not; women’s fertility is sharply age-graded, whereas men’s fertility is only gradu- ally age-graded; post-partum, women incur the costs of breast-feeding, whereas men do not. SST posits that humans have evolved psychological and strategic mating adaptations to these sex-linked differences in reproductive biology.
Regarding the temporal dimension, humans have evolved a long-term mating strategy marked by heavy commitment, long-term pair-bonding, and biparental investment. This may seem obvi- ous, but this sort of long-term committed mating is extremely rare among mammals, characterizing only 3–5%. Humans also have short-term uncom- mitted matings – one-night stands, casual hookups, brief affairs (e.g., Scelza 2011; Symons 1979). SST posits that the adaptive problems men and women recurrently had to solve differed as a function of this important temporal dimension.
Biological sex and temporal context generate a two-by-two matrix of adaptive problems, as shown in Table 1.
The Psychology of Short-Term Mating for Men and Women
Based in part on Trivers’s (1972) theory of paren- tal investment and sexual selection, SST posits that men had to solve adaptive problems of short-term mating such as increasing the number of sex partners accessible, identifying which women are sexually available or accessible, and minimizing the cost, risk, and amount of invest- ment in each mating opportunity. A large volume of empirical data supports these predictions. Men, compared to women, are more motivated by short-term sex, desire a larger number of sex part- ners, let less time elapse before seeking sexual intercourse, find attractive women who display cues to easy sexual accessibility, and show a psy- chology and attendant behavior to minimize investment and entangling commitments in short-term mating contexts (Buss and Schmitt 1993; Haselton and Buss 2001; Schmitt 2003).
Women pursuing a short-term mating strategy face a different set of adaptive challenges. These include securing immediate access to economic resources, choosing sex partners with high-quality genes, evaluating short-term mates as potential long-term prospects, and cultivating potential backup mates for the goal of mate switching. Numerous studies support these predictions. Women prioritize extravagant resource displays in short-term mating (Buss and Schmitt 1993). They shift to preferring men high in masculine appearance and symmetrical features, two of which are hypothesized cues to good genes (Gildersleeve et al. 2014). They cultivate backup mates, become distressed when their backup mates fall in love with others, and sometimes use short-term mating to exit an unhappy mating rela- tionship to trade up to a better partner (e.g., Buss et al. 2017). SST, in brief, posits that both women and men have short-term mating within their strategic repertoire and that their psychology of short-term mating is differentiated in precisely the domains in which the sexes have had to solve different adaptive challenges of short-term mating recurrently over evolutionary history.
2 Sexual Strategies Theory
The Psychology of Long-Term Mating for Men and Women
In long-term mating, women and men face many similar adaptive problems, such as identifying a mate who will commit to them over the long haul, someone who will be a reliable partner, and some- one who will be a good parent. Both sexes appear to have adaptations to solve these problems, such as looking for signs of love (a cue to commit- ment), prioritizing dependability and emotional stability in long-term mate preferences, and valu- ing good parent and good partner qualities such as kindness and agreeableness (Buss 1989, 2016; Buss and Shackelford 2008).
Men seeking a long-term mate have had to solve a critical adaptive problem – choosing a fertile mate or one who has high future reproduc- tive potential. Since ovulation is relatively concealed in humans and fertility cannot be detected directly, SST posited that men would prioritize cues statistically correlated with fertility. Since women’s fertility is sharply age-graded, this yielded the predictions that men would prioritize physical attractiveness, since appearance provides a bounty of observable cue to youth and health and hence to fertility. Abundant empirical evi- dence supports this set of predictions. Men world- wide, compared with women, place a greater priority on physical attractiveness and relative
youth in long-term mating (Buss 1989; Buss and Schmitt 1993; Kenrick and Keefe 1992). Due to the adaptive problem of internal female fertiliza- tion and gestation, men seeking long-term mates also had to prioritize cues to mates that would increase probability of their paternity in offspring. And indeed, men place tremendous value on sex- ual fidelity in a long-term mate and dislike any indications of a history of promiscuous mating (Buss and Schmitt 1993). Men also have post- mate selection adaptations, such as sexual jeal- ousy and mate-guarding effort, that function to increase the odds that their long-term commitment in one woman will result in offspring that are their own rather than those of rivals (Buss 2000; Daly et al. 1982).
SST posits that women pursuing a long-term mating strategy will prioritize, among other things, men who are both able to acquire resources and willing to invest those resources in them rather than in rival women. A large body of cross-cultural evidence supports this hypothesis. Women worldwide, compared to men, value resources and the qualities that lead to resources in long-term mates such as social status, ambition, and industriousness (Buss 1989). SST also posits that women had to solve the problem of protection and so will value men capable of protecting them from other men. Women indeed prioritize physi- cal formidability, tallness, and athletic prowess,
Sexual Strategies Theory, Table 1 Mate selection problems men and women confront in short-term and long-term mating contexts
Mating type Men Women
Short-term Increasing partner number Immediate resources
Identifying sexually accessible women Evaluating ST as LT mates
Minimizing cost and risk Identifying good genes
Minimizing commitment Mate insurance, backup mates
Identifying fertile women Mate switching
Long-term Paternity probability Men able to invest
Female reproductive value Men willing to invest
Good parenting abilities Good parenting abilities
Gene quality Gene quality
Relationship load Relationship load
Longevity probability Physical protection
Table is adapted from Table 1 of Buss and Schmitt (1993), p. 207
Sexual Strategies Theory 3
suggesting adaptations to solve this adaptive problem (Buss 2016).
Mating Psychology Is Context Dependent
Sexual strategies theory was designed as a com- plex theory of mating, positing a psychology con- tingent on biological sex and temporal context as central. Although abundant evidence has cumu- lated since it was first proposed in 1993, SSTwas designed to be open ended rather than the “last word” on evolved human mating strategies. Indeed, its authors articulated an agenda for future theorists and researchers that identified other likely contexts to which our psychology of mating would be contingent. One is mate value or a person’s level of desirability on the mating mar- ket. A second is sex ratio or the relative proportion of men to women in any given mating pool. A third is an ecology of parasite prevalence. Research has confirmed that these and other con- texts do importantly influence mating strategies (e.g., Buss and Shackelford 2008; Gangestad and Buss 1993; Schmitt 2016).
The authors of SST also speculated that indi- vidual differences were important and had to be explained by any complete theory of human mat- ing strategies. Research since 1993 has increas- ingly focused on individual differences. As one example, research on the “dark triad” of person- ality traits (narcissism, Machiavellianism, and psychopathy) has shown that high scorers are more likely to pursue short-term mating, more likely to use deception as a mating tactic, and may even be more likely to use coercion or force by bypassing a cardinal feature of women’s mat- ing strategy – female choice (Jonason et al. 2009). A second example, only dimly recognized by SST in 1993, is the importance of “good genes” in mate selection (e.g., Miller 2000).
Our evolved psychology of mating is extremely complex. We now know that theories of
mating prior to SST were extraordinarily simplistic. Humans do not have a single mating motive that remains invariant across domains, tem- poral contexts, and biological sexes. Instead, humans have mating adaptations sensitive to tem- poral context, to the challenges each sex has recur- rently faced, and to personal, social, and ecological factors such as mate value, sex ratio, and parasite prevalence. Every month, new “design features” of mating adaptations are being discovered, such as the importance of cues to sexual exploitability to short-term sexual attraction (Goetz et al. 2012), the relevance of personality to mating strategy pursued (Jonason et al. 2009; Schmitt 2016), and shifts from one sexual strategy to another depending on circumstances such as age, relationship history, ecology, and culture. Although we believe that SST, as originally formulated, provides many of the fundamentals of human mating that have been robustly supported by subsequent decades of empirical research, much new knowledge has been discovered about mating that requires addi- tions and expansions of its original formulation.
▶David Buss ▶Differential Parental Investment ▶Long-Term Mating ▶Men’s Long-Term Strategies ▶Men’s Short-Term Strategies ▶ Sex Differences in Parenting and Parental Investment
▶ Sex Differences in Short-Term Mating Preferences
▶ Sex Differences Long-Term Mating in Preferences
▶ Sexual Conflict and Sex Differences in Parental Investment
▶ Sexual Strategies Theory ▶ Short-Term Mating ▶The Evolution of Desire ▶Women’s Long-Term Strategies ▶Women’s Short-Term Strategies
4 Sexual Strategies Theory
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Sexual Strategies Theory 5
- Sexual Strategies Theory
- The Two Major Axes of Sexual Strategies Theory
- The Psychology of Short-Term Mating for Men and Women
- The Psychology of Long-Term Mating for Men and Women
- Mating Psychology Is Context Dependent