The target article by Maestripieri et al. is a nice example of how people's market value affects others' willingness to help, hire, or otherwise confer benefits on them. The target article defines “market value” as one's physical attractiveness, but one's overall market value need not to be limited to the mating domain. Because sexual selection is part of social selection more generally (Lyon & Montgomerie Reference Lyon and Montgomerie2012; West-Eberhard Reference West-Eberhard1979; Reference West-Eberhard1983), mate choice is also a subset of partner choice more generally, where organisms choose whom to interact with for either sexual or nonsexual relationships. Hence, mates (or potential mates) are just one type of partner that people can choose, albeit a very important type. This commentary generalizes the points in the target article beyond physical attractiveness and mating potential.
Biological markets theory describes how organisms choose partners (Noë & Hammerstein Reference Noë and Hammerstein1994; Reference Noë and Hammerstein1995). It treats social interactions as occurring within a “market” for commodities, where some individuals are more desirable partners because of their greater ability, willingness, or availability to confer benefits upon partners (Barclay Reference Barclay2013; Reference Barclay and Buss2015; Reference Barclay2016). For example, in the mating domain, some partners are healthier, more fertile, more receptive, or better parents, or they carry “good genes” that offspring will inherit. Courting someone with these traits will statistically increase one's fitness, so we evolved to be sexually attracted to cues of these traits. In nonmating domains, some partners provide more effective or more frequent aid, coalitional support, food, knowledge, skills, and so on; these commodities provide statistical fitness benefits, so we evolved to be socially attracted to them. One's overall “market value” in any domain is a composite of one's relative desirability based on the relevant traits, just as one's “mate value” is one's relative desirability based on mating-related traits alone.
Many principles that apply to mating relationships will also apply to nonmating relationships. For example, the target article shows that people are biased toward physically attractive individuals (high mate value) because it is more beneficial to attempt to mate with them. People are also biased toward individuals with other types of market value (i.e., other cues of ability or willingness to confer benefits). For example, high-status people receive preferential treatment in many domains, such as being listened to more often, receiving disproportionate shares of group productivity, and being excused from some social obligations or for bad behavior (reviewed by Henrich & Gil-White Reference Henrich and Gil-White2001; Kafashan et al. Reference Kafashan, Sparks, Griskevicius, Barclay, Cheng, Tracy and Anderson2014). People who appear competent are preferentially chosen as partners for tasks, from job searches to schoolyard team picking; competence-based choice occurs in chimpanzees (Melis et al. Reference Melis, Hare and Tomasello2006) and even in trout (Vail et al. Reference Vail, Manica and Bshary2014). People who appear wealthy elicit more compliance with their requests (e.g., Nelissen & Meijers Reference Nelissen and Meijers2011). People who appear altruistic or trustworthy are chosen more often as cooperative partners (e.g., Barclay Reference Barclay2004; Reference Barclay2006; Barclay & Willer Reference Barclay and Willer2007; Cuesta et al. Reference Cuesta, Gracia-Lázaro, Ferrer, Moreno and Sánchez2015; Gallo & Yan Reference Gallo and Yan2015), selected as leaders (Milinski et al. Reference Milinski, Semmann and Krambeck2002), and even preferred as romantic partners (e.g., Arnocky et al., Reference Arnocky, Piché, Albert, Ouellette and Barclayin press; Barclay Reference Barclay2010). So although biases toward physically attractive people are important, they are the tip of the iceberg in terms of preferential treatment toward people with high market value. Future research should compare the relative importance of different market-related traits, such as how people trade off the physical attractiveness of (supposedly nonromantic) partners against their competence, status, wealth, cooperativeness, and so on.
Biological markets theory allows us to make further predictions about attractiveness biases, or indeed any biases toward people with high market value. First, the magnitude of bias for a given trait depends on supply and demand. Attractiveness biases should be higher in environments where physical attractiveness is in high demand or low supply, for example, because of high pathogen pressure (Gangestad & Buss Reference Gangestad and Buss1993) or when other needs like resources are relatively less important (Marlowe Reference Marlowe2003). There will be stronger biases toward wealthy people when resources are crucial, toward physically proficient people when physical coalitional conflict is common, and so on.
Second, the magnitude of any bias depends on the variance in that trait. It is pointless to choose partners based on traits with no variance. Choosiness about cooperators diminishes when most people are cooperative (McNamara et al. Reference McNamara, Barta, Frohmage and Houston2008), so attractiveness should matter less in environments where everyone is attractive, wealth should matter less when everyone is wealthy, and so on.
Third, biases for particular traits depend on people being able to potentially “consume” it. Single men should display larger biases toward attractive women than do married men, especially in strictly monogamous societies with few extra-pair matings (less so under polygyny). Attractiveness should be less important if the target is married, raising children, sexually unreceptive, or chaste. People who do not need a particular trait in a partner should display lower biases toward others who possess it, such as people who do not need a partner's help being less cooperative (Barclay & Reeve Reference Barclay and Reeve2012; Kafashan et al. Reference Kafashan, Sparks, Griskevicius, Barclay, Cheng, Tracy and Anderson2014).
Fourth, people who themselves have high market value should be more discriminating (e.g., more influenced by attractiveness) because they are more likely to succeed at attracting the desirable partners than would a low market value person (e.g., Little et al. Reference Little, Burt, Penton-Voak and Perrett2001). For example, attractive men should show stronger biases toward attractive women, good cooperators should show stronger biases toward cooperators, and so on. High market value in one domain can predict preferences in others, such as wealthy individuals showing stronger biases toward attractive partners or vice versa. Extremely unattractive individuals may even be biased against attractive people, whom they have no hope of attracting.
I have highlighted four general types of predictions, derived from biological markets theory, about attractiveness biases. This list is limited by space, not by the utility of the theoretical perspective. Maestripieri et al. have nicely documented biases toward people possessing one highly salient market-related trait (physical attractiveness); we look forward to further work on other market-related traits, how these biases vary with social and ecological circumstances, and the relative weight of each trait across situations.
The target article by Maestripieri et al. is a nice example of how people's market value affects others' willingness to help, hire, or otherwise confer benefits on them. The target article defines “market value” as one's physical attractiveness, but one's overall market value need not to be limited to the mating domain. Because sexual selection is part of social selection more generally (Lyon & Montgomerie Reference Lyon and Montgomerie2012; West-Eberhard Reference West-Eberhard1979; Reference West-Eberhard1983), mate choice is also a subset of partner choice more generally, where organisms choose whom to interact with for either sexual or nonsexual relationships. Hence, mates (or potential mates) are just one type of partner that people can choose, albeit a very important type. This commentary generalizes the points in the target article beyond physical attractiveness and mating potential.
Biological markets theory describes how organisms choose partners (Noë & Hammerstein Reference Noë and Hammerstein1994; Reference Noë and Hammerstein1995). It treats social interactions as occurring within a “market” for commodities, where some individuals are more desirable partners because of their greater ability, willingness, or availability to confer benefits upon partners (Barclay Reference Barclay2013; Reference Barclay and Buss2015; Reference Barclay2016). For example, in the mating domain, some partners are healthier, more fertile, more receptive, or better parents, or they carry “good genes” that offspring will inherit. Courting someone with these traits will statistically increase one's fitness, so we evolved to be sexually attracted to cues of these traits. In nonmating domains, some partners provide more effective or more frequent aid, coalitional support, food, knowledge, skills, and so on; these commodities provide statistical fitness benefits, so we evolved to be socially attracted to them. One's overall “market value” in any domain is a composite of one's relative desirability based on the relevant traits, just as one's “mate value” is one's relative desirability based on mating-related traits alone.
Many principles that apply to mating relationships will also apply to nonmating relationships. For example, the target article shows that people are biased toward physically attractive individuals (high mate value) because it is more beneficial to attempt to mate with them. People are also biased toward individuals with other types of market value (i.e., other cues of ability or willingness to confer benefits). For example, high-status people receive preferential treatment in many domains, such as being listened to more often, receiving disproportionate shares of group productivity, and being excused from some social obligations or for bad behavior (reviewed by Henrich & Gil-White Reference Henrich and Gil-White2001; Kafashan et al. Reference Kafashan, Sparks, Griskevicius, Barclay, Cheng, Tracy and Anderson2014). People who appear competent are preferentially chosen as partners for tasks, from job searches to schoolyard team picking; competence-based choice occurs in chimpanzees (Melis et al. Reference Melis, Hare and Tomasello2006) and even in trout (Vail et al. Reference Vail, Manica and Bshary2014). People who appear wealthy elicit more compliance with their requests (e.g., Nelissen & Meijers Reference Nelissen and Meijers2011). People who appear altruistic or trustworthy are chosen more often as cooperative partners (e.g., Barclay Reference Barclay2004; Reference Barclay2006; Barclay & Willer Reference Barclay and Willer2007; Cuesta et al. Reference Cuesta, Gracia-Lázaro, Ferrer, Moreno and Sánchez2015; Gallo & Yan Reference Gallo and Yan2015), selected as leaders (Milinski et al. Reference Milinski, Semmann and Krambeck2002), and even preferred as romantic partners (e.g., Arnocky et al., Reference Arnocky, Piché, Albert, Ouellette and Barclayin press; Barclay Reference Barclay2010). So although biases toward physically attractive people are important, they are the tip of the iceberg in terms of preferential treatment toward people with high market value. Future research should compare the relative importance of different market-related traits, such as how people trade off the physical attractiveness of (supposedly nonromantic) partners against their competence, status, wealth, cooperativeness, and so on.
Biological markets theory allows us to make further predictions about attractiveness biases, or indeed any biases toward people with high market value. First, the magnitude of bias for a given trait depends on supply and demand. Attractiveness biases should be higher in environments where physical attractiveness is in high demand or low supply, for example, because of high pathogen pressure (Gangestad & Buss Reference Gangestad and Buss1993) or when other needs like resources are relatively less important (Marlowe Reference Marlowe2003). There will be stronger biases toward wealthy people when resources are crucial, toward physically proficient people when physical coalitional conflict is common, and so on.
Second, the magnitude of any bias depends on the variance in that trait. It is pointless to choose partners based on traits with no variance. Choosiness about cooperators diminishes when most people are cooperative (McNamara et al. Reference McNamara, Barta, Frohmage and Houston2008), so attractiveness should matter less in environments where everyone is attractive, wealth should matter less when everyone is wealthy, and so on.
Third, biases for particular traits depend on people being able to potentially “consume” it. Single men should display larger biases toward attractive women than do married men, especially in strictly monogamous societies with few extra-pair matings (less so under polygyny). Attractiveness should be less important if the target is married, raising children, sexually unreceptive, or chaste. People who do not need a particular trait in a partner should display lower biases toward others who possess it, such as people who do not need a partner's help being less cooperative (Barclay & Reeve Reference Barclay and Reeve2012; Kafashan et al. Reference Kafashan, Sparks, Griskevicius, Barclay, Cheng, Tracy and Anderson2014).
Fourth, people who themselves have high market value should be more discriminating (e.g., more influenced by attractiveness) because they are more likely to succeed at attracting the desirable partners than would a low market value person (e.g., Little et al. Reference Little, Burt, Penton-Voak and Perrett2001). For example, attractive men should show stronger biases toward attractive women, good cooperators should show stronger biases toward cooperators, and so on. High market value in one domain can predict preferences in others, such as wealthy individuals showing stronger biases toward attractive partners or vice versa. Extremely unattractive individuals may even be biased against attractive people, whom they have no hope of attracting.
I have highlighted four general types of predictions, derived from biological markets theory, about attractiveness biases. This list is limited by space, not by the utility of the theoretical perspective. Maestripieri et al. have nicely documented biases toward people possessing one highly salient market-related trait (physical attractiveness); we look forward to further work on other market-related traits, how these biases vary with social and ecological circumstances, and the relative weight of each trait across situations.