Encyclopedia of Evolutionary Psychological Science

Living Edition
| Editors: Todd K. Shackelford, Viviana A. Weekes-Shackelford

Relationship Choices and Sexuality

  • Peter K. JonasonEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-16999-6_3623-1


Romantic Relationship Behavioral Intention Mating Strategy Parental Investment Theory Sexual Strategy Theory 
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Sociosexuality was originally designed to capture individual differences in people’s willingness to engage in sexual behavior outside a formally/informally committed relationship. Work on the construct has moved from simple one-dimensional models, to models that incorporate the behavioral, attitudinal, and behavioral intention aspects of motivations to engage in casual sex, to, finally, encompassing an expansive model that describes a two-dimensional coordinate system composed of short-term mating interest and long-term mating interest. This model is especially useful in examining the emergent nature of the variety of apparent relationships that characterize the sexual landscape today.


Since Kinsey (circa 1953), it has been clear that there is a wide variety of sexual behaviors men and women engage in. Despite this, there is a pervasive myth of heterosexual monogamy in laypeople and researchers. This myth implies that the only acceptable form of sexual behavior is when it occurs in a committed relationship. While there are various reasons individuals might disapprove of sex outside of this context (e.g., health, religious), it is clear that individuals do engage in such behaviors in various relationship contexts. A more complete and accurate picture of human sexuality demands researchers to consider the various forms of sexuality individuals engage in. Indeed, even a cursory look at the animal kingdom reveals an apparently infinite array of sexual variety.

In the early 1990s, there was a paradigm shift in scientific thinking about the variety of sexual behavior and attitudes. Up until then, sex out of the context of marriage (i.e., casual sex) was seen as a pathology warranting treatment. Evolutionary psychologists began pointing out that engaging in casual sex might be adaptive for men and women (Buss and Schmitt 1993). By no longer pathologizing casual sex, researchers opened the proverbial floodgates to scientific inquiry into various questions related to motivations and measurement of people’s willingness to engage in casual sex (see Jonason and Balzarini 2016).

Relationship Choice

In efforts to try and account for individual differences in relationship choices, Simpson and Gangestad (1991) developed a construct called “sociosexuality.” This construct is meant to describe individual differences in people’s attitudes, behaviors, and desires for casual sex as a way to explain within – and between – sex relationship choices. For instance, items ask about willingness to have sex with someone sans feelings and how often individuals fantasize about someone other than their current partner. It has been quite useful in understanding broad-spectrum motivations to engage in casual sex, sex differences in such motivations, and is useful in providing some insight into people’s sexual psychology around the world.

However, there are a number of potential limitations with their conceptualization of sociosexuality. The one most attended to at present is its psychometric structure. For example, using the original scale’s items, more advanced tests (i.e., confirmatory factor analysis) revealed that the scale was better described as a two-dimensional system of sociosexual attitudes and sociosexual behaviors, dimensions that differ in their associations with narcissism and hostility (Webster and Bryan 2007). This two-dimensional model was further improved in Penke and Asendorpf (2008) to include sociosexual desires. These researchers attempted to understand sociosexuality as a manifestation of the classic social psychological distinctions of attitudes, behaviors, and behavioral intentions.

Another limitation of the initial work on sociosexuality was that it treated human sexuality in a rather black and white, dichotomous manner with one-night stands and serious romantic relationships treated as the only relationships available to engage in. Partly, this may be the result of efforts to reduce cognitive effort and to simplify research. However, this is a suboptimal solution as between 25% and 75% (see Jonason et al. 2012) of sexual acts committed by adolescents and college students happen in the context of sexual relationships that lack formal commitment (in contrast to serious romantic relationships) but are recurring acts committed by those with more than a passing acquaintanceship (in contrast with one-night stands). In addition, individuals appear to engage in non-relational sex for reasons thought to be confined to serious romantic relationships (e.g., emotional intimacy; Jonason 2013). While prior research has treated all casual sex as the same, there is evidence that each has its own functions and characteristic types of sexual and emotional acts (Jonason et al. 2010; Jonason and Balzarini 2016).

If one takes a step back, however, the real problem with using the sociosexuality construct to account for variance in relationship choice is that it treats motivations to engage in casual sex and motivations to engage in committed relationships as opposite ends of the same spectrum when there are likely multiple competing interests at once (see Jonason and Balzarini 2016). In a third conceptualization of sociosexuality (Jackson and Kirkpatrick 2007), researchers highlighted the theoretically important dimensions of long-term mating interest, short-term mating interest, and past sexual experiences. Such an attempt better highlights the multidimensional nature of human mating strategies and may better allow researchers to capture the range of potential relationships people may engage in. Despite this theoretically relevant dimensional structure, researchers have not taken a fully evolutionary approach to relationship choice.

Importantly, evolutionary theory, as applied to all manner of human existence including, but not limited to, relationship choice, suggests observable patterns in the world emerge from the competitive interactions of lower-order agents/factors without any overarching plan/planner, that is, relationships, as seen from our day-to-day lives, are not natural kinds but, instead, are the result of processes going on within people, societies, and couples. Relationships are likely the result of negotiations or, in other words, responses to numerous socioecological constraints imposed by those within (e.g., the partners) and outside relationships (e.g., society), but also ecological conditions like the availability of quality mates and resources (Jonason and Balzarini 2016). To treat relationships as distinct phenomena fails to deal with the fact that every relationship is different over a person’s lifetime but also across individual relationships.

Emergent Relationships

In hopes of convincing the reader that relationships are emergent solutions to conditions, a review of some (but not all) relationship types is presented next (see Jonason and Balzarini 2016). For instance, polyandry tends to occur in locations where the means by which resources are extracted from the earth are so labor-intensive that it takes multiple men to work their farm. Alternatively, polygyny is an option made available by a localization of resources. And last, polyamory might be a function of an interaction of individual differences in jealousy responsivity, the cobbling together of one’s sexual and security needs from multiple sources, and the desire to seek secondary benefits like excitement. While these options represent “extreme” solutions to the psychosocial and reproductive tasks organisms, including humans, face, they are expressions of a mating system that is flexible to “cultural” conditions. Less extreme solutions might be found in booty-call relationships or friends-with-benefits where latent mating systems interact with technologies (e.g., mobile phones) to enable mating success (Jonason et al. 2009, 2010).

An important aspect of this emergent solution hypothesis (see Jonason and Balzarini 2016; Jonason et al. 2012) is that there are winners and losers in the battle of the sexes as would be expected from sexual strategies theory a la parental investment theory (Buss and Schmitt 1993). In terms of the present discussion, in serious romantic relationships, women may gain more than men do as the former have secured the dedicated resources of a single man. In contrast, in one-night stands, men may gain more than women in that they gain access to low-investment sex. However, most research assumes stark zero-sum solutions in relationships. Instead, in negotiations, middle-ground or hybrid relationships may emerge in the form of mildly positive-sum relationships where both partners win something when they compromise a little. If we assume that people have ideal standards in their partners, any willingness to deviate from those ideals acts as a compromise (Li et al. 2002). While a woman engaging in a one-night stand may have to fully compromise what she wants (excepting sexual pleasure), a woman who engages in a booty-call relationship may get some of what she wants. In an idealized world, people would not need to compromise, but as the alternative to not doing so is potential reproductive oblivion, evolution would have fashioned flexibility into the system.


In conclusion, the utility of sociosexuality in hopes of accounting for individual differences in relationship choices has progressed like most good science, starting with simplicity and advancing to a more complicated, comprehensive conceptualization known as strategic pluralism (Gangestad and Simpson 2000). This hypothesis suggests that flexibility in mating systems is in-built as over generations individuals who could be flexible in their relationship choices had increased reproductive fitness. For instance, the purely short-term maters would have had trouble securing a partner, and their offspring would have not fared well, whereas the purely long-term maters would be overly invested in a single partner and unable to switch if the need emerged. Indeed, even gibbons (sp. Hylobates), the most “monogamish” (lesser) ape, are not fixed into monogamy. Instead, humans, like gibbons, may be able to swing from one mating strategy to another as the need arises. That is, the sexual variety observed in the world is the solution, not the problem to life’s greatest task: reproduction.



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© Springer International Publishing AG 2016

Authors and Affiliations

  1. 1.School of Social Sciences and PsychologyWestern Sydney UniversityMilperraAustralia