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The Evolutionary Psychology of Facial Beauty

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The Evolutionary Psychology of Facial Beauty 25 Oct 2005 15:50 AR ANRV264-PS57-08.tex XMLPublishSM(2004/02/24) P1: OKZ 10.1146/annurev.psych.57.102904.190208 Annu. Rev. Psychol. 2006. 57:199–226 doi: 10.1146/annurev.psych.57.102904.190208 Copyright c 2006 by Annual Reviews. All rights reserved First published online as a Review in Advance on August 11, 2005 THE EVOLUTIONARY PSYCHOLOGY OF FACIAL BEAUTY Gillian Rhodes School of Psychology, University of Western Australia, Crawley, Perth, WA 6009, Australia; email: [email protected] KeyWords facial attractiveness, face perception, evolutionary psychology, mate choice, adaptation ■ Abstract What makes a face attractive and why do we have the preferences we do? Emergence of preferences early in development and cross-cultural agree- ment on attractiveness challenge a long-held view that our preferences reflect ar- bitrary standards of beauty set by cultures. Averageness, symmetry, and sexual di- morphism are good candidates for biologically based standards of beauty. A critical review and meta-analyses indicate that all three are attractive in both male and fe- male faces and across cultures. Theorists have proposed that face preferences may be adaptations for mate choice because attractive traits signal important aspects of mate quality, such as health. Others have argued that they may simply be by-products of the way brains process information. Although often presented as alternatives, I ar- gue that both kinds of selection pressures may have shaped our perceptions of facial beauty. CONTENTS INTRODUCTION .................................................... 200 WHAT MAKES A FACE ATTRACTIVE? ................................. 201 Averageness ....................................................... 202 ......................................................... by Stanford University Robert Crown Law Lib. on 01/09/07. For personal use only. Symmetry 205 Annu. Rev. Psychol. 2006.57:199-226. Downloaded from arjournals.annualreviews.org Sexual Dimorphism ................................................. 208 Summary .......................................................... 211 THE EVOLUTION OF PREFERENCES .................................. 211 Preferences as Adaptations for Mate Choice .............................. 212 Preferences as By-Products of How Brains Process Information ....................................................... 216 CONCLUSIONS AND FUTURE DIRECTIONS ............................ 218 0066-4308/06/0110-0199$20.00 199 25 Oct 2005 15:50 AR ANRV264-PS57-08.tex XMLPublishSM(2004/02/24) P1: OKZ 200 RHODES INTRODUCTION ...[O]ur inner faculties are adapted in advance to the features of the world in which we dwell .... [O]ur various ways of feeling and thinking have grown to be what they are because of their utility in shaping our reactions on the outer world. (James 1892/1984, p. 11) There are few more pleasurable sights than a beautiful face. Attractive faces activate reward centers in the brain (Aharon et al. 2001, O’Doherty et al. 2003), they motivate sexual behavior and the development of same-sex alliances (Berscheid & Reis 1998, Berscheid & Walster 1974, Feingold 1990, Rhodes et al. 2005c, Thornhill & Gangestad 1999), and they elicit positive personality attributions (the “what is beautiful is good” stereotype—Dion et al. 1972, Eagly et al. 1991, Langlois et al. 2000) and positive treatment in a variety of settings (Hosoda et al. 2003, Langlois et al. 2000). It is not surprising, therefore, that philosophers, scientists, and ordinary people have long puzzled over what makes a face attractive and why we have the preferences we do (Etcoff 1999). A long-held view in the social sciences is that standards of beauty are arbi- trary cultural conventions (Berry 2000, Etcoff 1999). Even Darwin favored this view after observing large cultural differences in beautification practices (Darwin 1998/1874). However, two observations suggest that some preferences may be part of our biological, rather than our cultural, heritage. First, people in different cultures generally agree on which faces are attractive (Cunningham et al. 1995; Langlois et al. 2000; Perrett et al. 1994, 1998; Rhodes et al. 2001b, 2002; but see Jones & Hill 1993 for weaker agreement). Second, preferences emerge early in development, before cultural standards of beauty are likely to be assimilated (Geldart et al. 1999; Langlois et al. 1987, 1991; Rubenstein et al. 1999, 2002; Samuels et al. 1994; Samuels & Ewy 1985; Slater et al. 1998, 2000). Because preferences affect mate choice (e.g., Rhodes et al. 2005c), they may have evolved through sexual selection, whereby traits (including preferences) en- hance reproductive success. Three candidates have been proposed for sexually by Stanford University Robert Crown Law Lib. on 01/09/07. For personal use only. selected preferences. The first is a preference for averageness, i.e., proximity to Annu. Rev. Psychol. 2006.57:199-226. Downloaded from arjournals.annualreviews.org a spatially average face for a population. The second is a preference for bilateral symmetry. The third is a preference for sexual dimorphism, i.e., for feminine traits in female faces and masculine traits in male faces. These traits have been proposed to signal mate quality so that preferences for them may be adaptations for finding good mates (Gangestad & Thornhill 1997; Penton-Voak & Perrett 2000a; Rhodes & Zebrowitz 2002; Thornhill & Gangestad 1993, 1999; Symons 1979). However, it is also possible that these preferences are by-products of the way brains process information, with no link between preferred traits and mate quality (e.g., Enquist & Arak 1994, Jansson et al. 2002, Johnstone 1994). The first aim of this review is to assess the appeal of the three candidates for bi- ologically based preferences: for averageness, symmetry, and sexual dimorphism. 25 Oct 2005 15:50 AR ANRV264-PS57-08.tex XMLPublishSM(2004/02/24) P1: OKZ FACIAL BEAUTY 201 The second aim is to understand what evolutionary mechanisms may have shaped these preferences and to try to resolve the debate about whether or not attractive traits signal mate quality. WHAT MAKES A FACE ATTRACTIVE? In his excellent book on beauty, Armstrong (2004) argues that beauty cannot be explained by a single principle, such as Hogarth’s serpentine line, mathematically harmonious proportions, or a match of form to function. Similarly, there is no gold standard for facial beauty. Components of attractiveness may include aver- ageness, symmetry, sexual dimorphism, a pleasant expression, good grooming, youthfulness (Berry 2000, Cunningham 1986, Etcoff 1999, Rhodes & Zebrowitz 2002, Thornhill & Gangestad 1999), and, for known faces, can reflect nonphysical characteristics, such as how much one likes the person (Kniffin & Wilson 2004). There may also be different kinds of attractiveness (e.g., sexual attractiveness, attractiveness as a potential ally, cuteness) with different affective and motivational consequences (e.g., sexual arousal, competitiveness, caregiving). However, most studies have simply asked people to judge “attractiveness,” which assumes some common aesthetic/affective judgment for faces of both sexes. These judgments appear to reflect sexual attractiveness for opposite-sex faces, with responses cor- relating almost perfectly with ratings of desirability to date (0.97) or marry (0.93) (Cunningham et al. 1990). They may also elicit judgments of sexual attractive- ness (to the opposite sex) for same-sex faces, because men and women generally agree on attractiveness (Langlois et al. 2000). This agreement could reflect the assessment of sexual attractiveness in same-sex faces, to assess their danger as potential rivals for mates, or it could reflect some more generic aesthetic or affec- tive response that is made to all faces. Agreement about which faces are attractive not only occurs between men and women, but also between people from different cultures (e.g., Langlois et al. 2000). Therefore, contrary to the popular maxim that beauty is in the eye of the beholder, preferences are not highly idiosyncratic and we can sensibly ask, what makes a face attractive? Here I focus on averageness, symmetry, and sexual dimorphism, the three can- by Stanford University Robert Crown Law Lib. on 01/09/07. For personal use only. Annu. Rev. Psychol. 2006.57:199-226. Downloaded from arjournals.annualreviews.org didates for biologically based preferences. There is now a critical mass of studies, making a meta-analytic, as well as conceptual, review useful. Meta-analyses com- bine data across studies, giving estimates of the strength of the association (effect size) between attractiveness and given traits. They will also allow us to examine whether preferences generalize across sex and race of faces, and to assess formally the effects of potentially important methodological variables. Separate meta-analyses were conducted for averageness, symmetry, and sexual dimorphism. The results are summarized in Table 1 (for details, see the Supplemen- tal Material link for Electronic Appendices 1–3 in the online version of this chap- ter at http://www.annualreviews.org/). Effect size R’s are reported, but analyses used Zr’s.Aninitial sexual dimorphism meta-analysis showed a large effect of face sex, F(1,38) = 26.16, p < 0.0001 (0.64 ± 0.39, N = 18, female faces; 25 Oct 2005 15:50 AR ANRV264-PS57-08.tex XMLPublishSM(2004/02/24) P1: OKZ 202 RHODES TABLE 1 Summary of effect size (R) statistics for the attractiveness of averageness, symmetry, and sexual dimorphism. All calculations were conducted on Zr’s Attractiveness Attractiveness Attractiveness Attractiveness and and and and averageness symmetry femininity masculinity All faces Mean effect 0.52 0.25 0.64 −0.12 size (ES) Standard 0.41 0.34 0.39 0.55 deviation 95% 0.42–0.61 0.16–0.33 0.51–0.74 −0.35–0.14 Confidence interval Number of 20 23 10 15 studies Number of face 45 63 18 22 samples Mean weighted 0.54 0.23 0.61 0.16 ES (by N faces) Normal faces only Mean ES 0.40 0.23 0.64 0.35 Standard 0.33 0.23 0.45 0.20 deviation 95% 0.29–0.51 0.17–0.30 0.41–79 0.23–0.45 Confidence interval Number of 27 42 9 10 distinct face samples Mean weighted 0.40 0.24 0.58 0.27 ES (by N faces) by Stanford University Robert Crown Law Lib.
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