Lowering Partner Standards in a Short-Term Mating Context
Humans are more selective when considering partners for a long-term relationship compared to a short-term one.
The characteristics modern men and women desire in a partner differ as a function of mating context. Overall, this pattern reflects a general “relaxing” of standards in a short-term mating context compared to a long-term one. For example, compared to a long-term partner, both sexes are willing to tolerate a prospective casual mate who is lower in intelligence, kindness, and social status (Kenrick et al. 1993; Li and Kenrick 2006).
However, not all standards are relaxed in the context of casual mating. Desire for physical attractiveness in a potential partner, for instance, appears to be maintained, or even enhanced, in a short-term mating context compared to a long-term one (Kenrick et al. 1993; Li and Kenrick 2006). Understanding why standards are lower in some cases but not others requires both an appreciation of the challenges our ancestors faced when pursuing these two types of mating and how such challenges differed between the sexes.
As a species, humans mate within committed pair-bonds and uncommitted casual relationships (Buss and Schmitt 1993). Both types of mating conveyed a reproductive advantage to our ancestors under the right conditions, and each would have presented its own unique set of adaptive problems. As such, we evolved psychological adaptations to help us overcome these problems and draw us, given our circumstances, towards the most reproductively efficient type of mating (Thomas and Stewart-Williams 2018). It is the difference between these two sets of adaptations, or mating strategies, which cause potential long- and short-term partners to be held to different standards.
Global Standards for Long-Term Partners
Humans are a species which engage in mutual mate choice (Stewart-Williams and Thomas 2013). When looking for a long-term partner, both sexes hold high standards across a host of characteristics including physical attractiveness, kindness, and social status (Kenrick et al. 1993; Li et al. 2002). These modern day preferences exist because human ancestors evolved to be highly selective when pair-bonding to maximize their reproductive success. Ancestral humans who chose long-term mates indiscriminately risked heavily investing in a small number of poor quality offspring, potentially without (or with ineffective) parental support from their partners. Such outcome would have handicapped the reproductive fitness of both sexes. There are, of course, some differences between the sexes in how much they value individual traits within a long-term context. However, it is rare to find traits highly valued by only one sex (Buss 1989; Kenrick et al. 1993).
Men’s Standards for Short-Term Partners
Under certain conditions, ancestral humans could have maximized their reproductive fitness by foregoing pair-bonded mating and pursuing casual mating instead. This type of mating presents a unique set of adaptive problems which differ for each sex (Buss and Schmitt 1993). For ancestral men, casual mating offered the prospect of increased offspring quantity, with little to no investment. However, the success of this strategy would have depended on the availability of women willing to be uncommitted sex partners. Men with high standards for short-term partners would have limited this availability, especially given that highly attractive women may have been less likely to benefit from, and therefore pursue, short-term mating (Buss and Shackelford 2008). Thus, men evolved to have substantially relaxed standards for casual sex partners.
These evolved tendencies are visible in the preferences of modern men who, in the context of short-term mating, have lower standards across a broad array of characteristics including intelligence, conscientiousness, dominance, status, sexual history, and kindness (Buss and Schmitt 1993; Kenrick et al. 1993; Li and Kenrick 2006). One noticeable exception to this is the preference for physical attractiveness, which appears to be generally stronger in short-term contexts - likely due to its association with both fitness and fecundity (Li and Kenrick 2006; Singh and Young 1995). It is worth noting that men are not indiscriminate in their choice of casual partners. This is probably due to the historical risks associated with short-term mating, including harmed reputation, STI contraction, and being manipulated by lower quality women into committed relationships (Greiling and Buss 2000). However, these risks likely constituted a smaller threat to fitness than those faced by women.
Women’s Standards for Short-Term Partners
For ancestral women, casual mating could have enhanced fitness in several ways, mostly as the result of access to men of a higher mate value (Greiling and Buss 2000). These men, while reluctant to pair-bond with women of lower mate value, may have been willing to have casual sex with them to potentially increase their fitness with little to no investment. Thus, casual sex would have provided women with a way of securing the genes and resources of these men and may have given them an opportunity to coerce them into a pair-bond. Other benefits of short-term mating, such as manipulating a current partner, or practicing mate acquisition skills, may have been less related to the mate value of a prospective partner. Considering the benefits of short-term mating together, there would have been much less selective pressure on ancestral women to lower their minimum standards for short-term partners. Compared to men, women evolved to maintain higher standards for short-term partners, especially for characteristics that indicate high genetic quality.
Indeed, modern women relax their standards to a much lesser extent than men do. The attributes subject to the largest drop tend to be important for secure pair-bonding, such as family orientation and kindness (Li and Kenrick 2006). The desire for a physically attractive partner, however, tends to be either maintained or increased (Kenrick et al. 1993; Li and Kenrick 2006). Another reason why women evolved to be more discriminate about short-term partners is that choosing poor quality partners as casual mates has greater fitness consequences for women than men. Obligate levels of parental investment are small among male mammals, who are able to desert a partner after pregnancy. In contrast, immediate desertion is not an option for females who have to carry an infant to term (Stewart-Williams and Thomas 2013). Choosing a poor quality short-term partner would have seen the reproductive resources of ancestral women directed towards poor quality offspring.
In summary, while humans are highly selective about their long-term partners, they appear to have lower standards for casual partners. The intensity of this “mating context effect” differs between the sexes, with men having markedly relaxed standards compared to women. This sex difference likely stems from the different costs and benefits casual mating afforded ancestral humans.
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