After comparing explanations provided by economists, social psychologists, and evolutionary psychologists, Maestripieri et al. concluded that the evolutionary explanation best accounts for financial and prosocial biases in favor of attractive adults. According to the evolutionary explanation, these biases occur because attractiveness (1) indicates higher biological fitness such as health and fertility and (2) hence could activate mating goals, consciously or unconsciously, and (3) for a functional purpose of reproducing offspring with greater genetic quality. Although acknowledging the thoroughness of their review from an interdisciplinary perspective, I suggest that all three critical points of the evolutionary explanation proposed by Maestripieri et al. may have difficulty in standing up to scrutiny.
First, although the authors cited several articles' to support the idea that “human facial attractiveness is likely to be an indicator of overall quality” (sect. 2.1.3, para. 2), there was plenty of evidence suggesting no relationship between attractiveness and biological fitness (e.g., Gray & Boothroyd Reference Gray and Boothroyd2012; Kalick et al. Reference Kalick, Zebrowitz, Langlois and Johnson1998; Shackelford & Larsen Reference Shackelford and Larsen1999; Weeden & Sabini Reference Weeden and Sabini2005). Actually, the most recent review article cited by Maestripieri et al. also concluded that the supporting evidence was far from strong (Rhodes Reference Rhodes2006). Therefore, the indicating effect of attractiveness could at most be considered as a pending issue or might only exist in certain environments (Hunt et al. Reference Hunt, Bussiere, Jennions and Brooks2004). Interestingly, although females' waist-to-hip ratio (WHR) is a more reliable indicator of biological fitness in reality, males do not have universal preference for women with a low WHR (Yu & Shepard Reference Yu and Shepard1998).
Certainly, one may argue that it does not matter even if attractiveness does not indicate real biological fitness at all, as long as it has an indicating effect in people's minds such that people rate attractive individuals as more fit, as demonstrated by previous studies (e.g., Kalick et al. Reference Kalick, Zebrowitz, Langlois and Johnson1998). Although it might make sense, this reasoning at the same time would greatly corrode Maestripieri et al.'s critiques against explanations provided by economists and social psychologists. This is because the most critical evidence they cited to challenge these explanations was that in reality there is little or no evidence that attractive individuals are more productive, trustworthy, and competent, although people do exhibit an attractiveness halo, just as they perceive attractive persons as having higher biological fitness.
Second, the concept of “mating goal” is only a latent variable assumed by Maestripieri et al., and no study has directly manipulated or measured mating goals to investigate their roles in financial and prosocial biases listed by these authors. In other related research areas, although previous studies that manipulated mating goals showed that mating goals increased males' willingness to purchase conspicuous consumption items, as well as females' public helping tendency, a recent meta-analysis revealed strong evidence of either publication bias or p-hacking (or both; Shanks et al. Reference Shanks, Vadillo, Riedel, Clymo, Govind, Hickin, Tamman and Puhlmann2015). Further, none of eight pre-registered studies (with a total sample of more than 1,600 participants) replicated the mating effect, and an overall meta-analysis including all of these studies concluded an effect that was indistinguishable from zero (Shanks et al. Reference Shanks, Vadillo, Riedel, Clymo, Govind, Hickin, Tamman and Puhlmann2015). Therefore, the latent variable (i.e., mating goal) assumed by Maestripieri et al. seems like a river without headwaters or a tree without roots, given the insignificant effect even for explicit and direct manipulation of this variable.
Third, even if financial and prosocial biases in favor of attractive adults were driven by mating goals, they may not result from a functional purpose of increasing genetic quality for offspring. If so, attractiveness should have been valued more in the context of developing a long-term relationship. However, this is not the case. By contrast, both men and woman value physical attractiveness very highly in the context of short-term mating (Buss Reference Buss2003; Gangestad & Scheyd Reference Gangestad and Scheyd2005). Further, Maestripieri et al. relied on the evolutionary explanation to predict higher biases in favor of attractive same-sex individuals for homosexuals. This seems problematic because there is no reason to assume a relationship between homosexuality and gene passing.
When it comes back to why there are financial and prosocial biases in favor of attractive adults, there should be an alternative explanation that has nothing to with genetic continuity. As has been demonstrated, the perception of facial attractiveness is very complex, both in the large number of traits that determine attraction and in the variety of factors that alter attraction to particular faces (Little Reference Little2014). What might be most familiar to us is that facial attractiveness is highly dependent on sociocultural factors such as mass media influence and cultural transmission (e.g., Dakanalis & Riva Reference Dakanalis, Riva, Sams and Keels2013; Kenrick & Gutierres Reference Kenrick and Gutierres1980; Little Reference Little2014). In a specific population during a specific era, people tend to share a general standard of facial attractiveness (e.g., thin face with sharp chin in modern society and fat face with thick chin in Chinese Tang Dynasty for women), which assigns value to faces in line with such standard and makes these faces valuable and rewarding. This would directly explain why some regions in the brain's rewarding system, such as the medial orbitofrontal cortex, could be activated in response to both same-sex and opposite-sex attractive faces (O'Doherty et al. Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003; Winston et al. Reference Winston, O'Doherty, Kilner, Perrett and Dolan2007). Although there are some basic facial features determining attractiveness that seem universally accepted across cultures and times, such as symmetry, they are more likely to result from other mechanisms such as the need to recognize objects irrespective of their position and orientation in the visual word (Enquist & Arak Reference Enquist and Arak1994), rather than signaling genetic quality. Furthermore, for heterosexuals, because attractiveness in opposite-sex adults is related to sexual experience, which is also rewarding, it would not be surprising that other regions processing rewarding stimuli, such as the ventromedial prefrontal cortex, are activated by attractive opposite-sex faces (O'Doherty et al. Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003). Likewise, the rewarding system is also activated in response to attractive same-sex faces for homosexuals (Ishai Reference Ishai2007). Therefore, because of the rewarding property of attractiveness, in the labor market or economic games, attractive individuals would generally be treated better, especially when there is a potential chance for treaters who are in pursuit of a stimulating sexual experience.
After comparing explanations provided by economists, social psychologists, and evolutionary psychologists, Maestripieri et al. concluded that the evolutionary explanation best accounts for financial and prosocial biases in favor of attractive adults. According to the evolutionary explanation, these biases occur because attractiveness (1) indicates higher biological fitness such as health and fertility and (2) hence could activate mating goals, consciously or unconsciously, and (3) for a functional purpose of reproducing offspring with greater genetic quality. Although acknowledging the thoroughness of their review from an interdisciplinary perspective, I suggest that all three critical points of the evolutionary explanation proposed by Maestripieri et al. may have difficulty in standing up to scrutiny.
First, although the authors cited several articles' to support the idea that “human facial attractiveness is likely to be an indicator of overall quality” (sect. 2.1.3, para. 2), there was plenty of evidence suggesting no relationship between attractiveness and biological fitness (e.g., Gray & Boothroyd Reference Gray and Boothroyd2012; Kalick et al. Reference Kalick, Zebrowitz, Langlois and Johnson1998; Shackelford & Larsen Reference Shackelford and Larsen1999; Weeden & Sabini Reference Weeden and Sabini2005). Actually, the most recent review article cited by Maestripieri et al. also concluded that the supporting evidence was far from strong (Rhodes Reference Rhodes2006). Therefore, the indicating effect of attractiveness could at most be considered as a pending issue or might only exist in certain environments (Hunt et al. Reference Hunt, Bussiere, Jennions and Brooks2004). Interestingly, although females' waist-to-hip ratio (WHR) is a more reliable indicator of biological fitness in reality, males do not have universal preference for women with a low WHR (Yu & Shepard Reference Yu and Shepard1998).
Certainly, one may argue that it does not matter even if attractiveness does not indicate real biological fitness at all, as long as it has an indicating effect in people's minds such that people rate attractive individuals as more fit, as demonstrated by previous studies (e.g., Kalick et al. Reference Kalick, Zebrowitz, Langlois and Johnson1998). Although it might make sense, this reasoning at the same time would greatly corrode Maestripieri et al.'s critiques against explanations provided by economists and social psychologists. This is because the most critical evidence they cited to challenge these explanations was that in reality there is little or no evidence that attractive individuals are more productive, trustworthy, and competent, although people do exhibit an attractiveness halo, just as they perceive attractive persons as having higher biological fitness.
Second, the concept of “mating goal” is only a latent variable assumed by Maestripieri et al., and no study has directly manipulated or measured mating goals to investigate their roles in financial and prosocial biases listed by these authors. In other related research areas, although previous studies that manipulated mating goals showed that mating goals increased males' willingness to purchase conspicuous consumption items, as well as females' public helping tendency, a recent meta-analysis revealed strong evidence of either publication bias or p-hacking (or both; Shanks et al. Reference Shanks, Vadillo, Riedel, Clymo, Govind, Hickin, Tamman and Puhlmann2015). Further, none of eight pre-registered studies (with a total sample of more than 1,600 participants) replicated the mating effect, and an overall meta-analysis including all of these studies concluded an effect that was indistinguishable from zero (Shanks et al. Reference Shanks, Vadillo, Riedel, Clymo, Govind, Hickin, Tamman and Puhlmann2015). Therefore, the latent variable (i.e., mating goal) assumed by Maestripieri et al. seems like a river without headwaters or a tree without roots, given the insignificant effect even for explicit and direct manipulation of this variable.
Third, even if financial and prosocial biases in favor of attractive adults were driven by mating goals, they may not result from a functional purpose of increasing genetic quality for offspring. If so, attractiveness should have been valued more in the context of developing a long-term relationship. However, this is not the case. By contrast, both men and woman value physical attractiveness very highly in the context of short-term mating (Buss Reference Buss2003; Gangestad & Scheyd Reference Gangestad and Scheyd2005). Further, Maestripieri et al. relied on the evolutionary explanation to predict higher biases in favor of attractive same-sex individuals for homosexuals. This seems problematic because there is no reason to assume a relationship between homosexuality and gene passing.
When it comes back to why there are financial and prosocial biases in favor of attractive adults, there should be an alternative explanation that has nothing to with genetic continuity. As has been demonstrated, the perception of facial attractiveness is very complex, both in the large number of traits that determine attraction and in the variety of factors that alter attraction to particular faces (Little Reference Little2014). What might be most familiar to us is that facial attractiveness is highly dependent on sociocultural factors such as mass media influence and cultural transmission (e.g., Dakanalis & Riva Reference Dakanalis, Riva, Sams and Keels2013; Kenrick & Gutierres Reference Kenrick and Gutierres1980; Little Reference Little2014). In a specific population during a specific era, people tend to share a general standard of facial attractiveness (e.g., thin face with sharp chin in modern society and fat face with thick chin in Chinese Tang Dynasty for women), which assigns value to faces in line with such standard and makes these faces valuable and rewarding. This would directly explain why some regions in the brain's rewarding system, such as the medial orbitofrontal cortex, could be activated in response to both same-sex and opposite-sex attractive faces (O'Doherty et al. Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003; Winston et al. Reference Winston, O'Doherty, Kilner, Perrett and Dolan2007). Although there are some basic facial features determining attractiveness that seem universally accepted across cultures and times, such as symmetry, they are more likely to result from other mechanisms such as the need to recognize objects irrespective of their position and orientation in the visual word (Enquist & Arak Reference Enquist and Arak1994), rather than signaling genetic quality. Furthermore, for heterosexuals, because attractiveness in opposite-sex adults is related to sexual experience, which is also rewarding, it would not be surprising that other regions processing rewarding stimuli, such as the ventromedial prefrontal cortex, are activated by attractive opposite-sex faces (O'Doherty et al. Reference O'Doherty, Winston, Critchley, Perrett, Burt and Dolan2003). Likewise, the rewarding system is also activated in response to attractive same-sex faces for homosexuals (Ishai Reference Ishai2007). Therefore, because of the rewarding property of attractiveness, in the labor market or economic games, attractive individuals would generally be treated better, especially when there is a potential chance for treaters who are in pursuit of a stimulating sexual experience.