Trends in Cognitive Sciences
ReviewFacial attractiveness
Section snippets
Attractiveness as a health certificate
Facial attractiveness assessments are more similar than different across sexes and sexual orientations, ethnic groups, and ages from infants to the elderly7, 8, 9, 10, 11, 12, with correlations between two raters’ judgments typically in the range 0.3–0.5. Even within and between human groups with little or no contact with Western standards of beauty, there is appreciable agreement in facial attractiveness ratings11. Naturally, different societies do not place precisely the same value on all
Facial symmetry
Fluctuating asymmetry (FA) is a departure from symmetry in traits that are symmetrical at the population level. It is thought to result from developmental instability (the inability to perfectly express developmental design) and, therefore, reflects maladaptation31, 32. The primary causes of FA include mutations, pathogens and toxins. The evolution of humans with their co-evolving antagonists, such as pathogens and toxins in dietary plants, together with other coevolutionary antagonisms (e.g.
Facial averageness
Symons13 hypothesized that facial averageness is attractive because averageness is associated with above-average performance in tasks such as chewing and breathing. In other words, natural selection has a stabilizing effect on facial features (i.e. favors the mean) and, therefore, averageness is associated with good phenotypic condition. Thornhill and Gangestad2 suggested that preference for average trait values in some facial features (not the secondary sex traits) could have evolved because,
The handicap principle
The perpetual ‘beauty contests’ of human evolutionary history would be expected to have selected signal-receiving adaptations as well as adaptations in the outgoing signals. Evolutionary psychology addresses both the immediate workings of psychological adaptations responsible for physical attractiveness judgments, as well as adaptations that function to create, during development, the physical features that are judged.
The most prominent evolutionary theory of social signals, including sexual
Male facial sex-hormone markers
In many species, including humans, testosterone production and metabolism mobilizes resources for the efforts of males to attract and compete for mates49, 50. It results in increased musculature and energy utilization through muscular activity51 and, accordingly, draws resources away from other activities, such as immune function52. In men, testosterone levels increase after competitive success, suggesting that its production is sensitive to cues about ability to compete with other males53.
Trade-offs in facial traits
Studies examining the associations between attractiveness and masculine features yield mixed findings. Some show preference for masculine facial features56, whereas others find preference for near-average or feminized facial features57, 58, 59. Given the signaling theory just presented, what could be the reason for this? Although masculine features might honestly signal male intrasexual competitive ability, they do not honestly signal all traits valued in a male mate. Women rate men with
Preference changes during the menstrual cycle
Women’s preferences shift during the menstrual cycle. The first such shift to be demonstrated involves the olfactory preference that women have for the scent of symmetrical men (mentioned above). This preference is specific to normally ovulating women (those not using the contraceptive pill) during the high-fertility phase of their menstrual cycle (the mid-to-late follicular phase). Women do not exhibit this preference during the low-fertility, luteal phase or when using a contraceptive pill43,
Individual differences in women’s preferences
The view that cues suggest multiple valued traits, which might be differentially valued in varying circumstances, could yield predictions about how other factors affect attractiveness judgments. For example, women vary in motivation for short-term mating relationships. These individual differences probably reflect a conditional mating strategy, with women pursuing alternate mating tactics (i.e. short-term mating or long-term mating) depending on cues, because those cues, such as the amount of
Female facial sex-hormone markers
Estrogen could be a handicapping sex hormone for women in a similar way that testosterone acts for men30. Estrogen signals the readiness of a woman to exert reproductive effort and is therefore a signal of fertility. Because estrogen can be expected to draw resources away from other bodily functions (e.g. immune function or repair mechanisms), it could affect mortality. The signal value of estrogen as a fertility cue could therefore result in the evolution of estrogen displays and the capacity
Mate-choice copying
Females and males can choose mates independently of other same-sex individuals’ mate choices, or they can copy the mate choices of these individuals. There is now solid evidence that females of certain species of birds and fish strategically copy the mate choice of conspecific females when discrimination between potential mates is based on less than reliable cues, and when other females have greater knowledge of males76, 77. Human studies suggest that women also copy mate choices, and more so
Conclusions
The adaptationist examines traits for evidence of special design: specialized features that could reveal what function, if any, the trait served in evolutionary history and led to its selection. People make aesthetic judgments of others, which has an important affect on mate and friendship choice. From an adaptationist perspective, it would be odd if the psychological features responsible for these discriminations did not serve some function in humans’ evolutionary past. Adaptationists have
Outstanding questions
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EEA-focused research is needed to clarify the relationships between facial attractiveness and health. Is individual variation in facial asymmetry, facial averageness and putative hormone markers related to measures of immunocompetence and overall condition, as predicted by the hypothesis that beauty is a health certificate?
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How do measures of symmetry, averageness and hormone markers relate to one another, and how do olfactory preferences relate to visual preferences? If they tap somewhat
Acknowledgements
For helpful comments on the paper, we thank V. Johnston, I. Penton-Voak and the anonymous referees.
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