sciencedirect.comPII: S1090-5138(01)00083-6Facial symmetry and judgements of apparent healthSupport for a ‘‘good genes’’ explanation of theattractiveness–symmetry relationshipB.C. Jones*, A.C. Little, I.S. Penton-Voak, B.P. Tiddeman,D.M. Burt, D.I. PerrettSchool of Psychology, University of St. Andrews, St. Andrews, Fife KY16 9AJ, Scotland, UKReceived 27 February 2001; received in revised form 11 April 2001; accepted 5 June 2001AbstractThe ‘‘good genes’’ explanation of attractiveness posits that mate preferences favour healthyindividuals due to direct and indirect benefits associated with the selection of a healthy mate.Consequently, attractiveness judgements are likely to reflect judgements of apparent health. Onephysical characteristic that may inform health judgements is fluctuating asymmetry as it may act as avisual marker for genetic quality and developmental stability. Consistent with these suggestions, anumber of studies have found relationships between facial symmetry and facial attractiveness. In Study1, the interplay between facial symmetry, attractiveness, and judgements of apparent health wasexplored within a partial correlation design. Findi ngs suggest that the attractiveness – symmetryrelationship is mediated by a link between judgements of apparent health and facial symmetry. InStudy 2, an opposite-sex bias in sensitivity to facial symmetry was observed when judging health.Thus, perceptual analysis of symmetry may be an adaptation facilitating discrimination betweenpotential mates on the basis of apparent health. The findings of both studies are consistent with a‘‘good genes’’ explanation of the attractiveness–symmetry relationship and problematic for the claimthat symmetry is attractive as a by-product of the ease with which the visual recognition systemprocesses symmetric stimuli. D 2001 Elsevier Science Inc. All rights reserved.Keywords: Faces; Attractiveness; Perceived health; Mate preferences; Asymmetry1090-5138/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved.PII: S 1 090-5138(01)00083-6* Corresponding author. Tel.: +44-1334-46-2088; fax: +44-1334-46-3042.E-mail address: [email protected] (B.C. Jones).Evolution and Human Behavior 22 (2001) 417–4291. IntroductionThe ‘‘good genes’’ account of attractiveness posits that mate preferences may haveevolved to favour healthy individuals due to direct and indirect benefits associated with theselection of a healthy mate (Andersson, 1994; Gangestad & Simpson, 2000; Miller & Todd,1998; Thornhill & Gangestad, 1993, 1999). If this is the case, attractiveness judgements arelikely to reflect judgements of health (Grammer & Thornhill, 1994). It has also beensuggested that fluctuating asymmetry is a visual marker for genetic quality and devel-opmental stability—the ability to maintain good health in the face of environmental insults(Gangestad & Simpson, 2000; Møller & Swaddle, 1997; Møller & Thornhill 1997;Thornhill & Møller, 1997).Consistent with these suggestions, a number of studies have found that symmetry in realfaces is associated with judgements of facial attractiveness (Grammer & Thornhill, 1994;Hume & Montgomerie, 2001; Mealey, Bridgestock, & Townsend, 1999; Rhodes, Proffitt,Grady, & Sumich, 1998; Rhodes, Sumich, & Byatt, 1999; Scheib, Gangestad, & Thornhill,1999). Moreover, preferences for faces that have been ‘‘morphed’’ to be more symmetricalhave also been reported (Perrett et al., 1999; Rhodes et al., 1998; Rhodes, Yoshikawa, et al.,2001). Consequently, many researchers have concluded that symmetry is a visual cue to facialattractiveness. For some, however, the link remains in debate (e.g., Penton-Voak et al., 2001;Scheib et al., 1999; Swaddle & Cuthill, 1995).Both Grammer and Thornhill (1994) and Penton-Voak et al. (2001) found thatjudgements of health were related to symmetry in male faces. In line with these findings,Rhodes, Zebrowitz, et al. (2001) reported associations between rated facial symmetry andjudgements of apparent health for both male and female faces. The apparent health ofsymmetric faces could, however, reflect an ‘‘attractiveness halo’’ where positive attributes(e.g., extraversion, stability, and good health) are ascribed to good looking, symmetricalindividuals (Penton-Voak et al., 2001). Indeed, there is some evidence that apparent goodhealth may simply be a stereotype associ ated with attractive indi viduals (Kalick,Zebrowitz, Langlois, & Johnson, 1998). If the relationship between symmetry andjudgements of apparent health was mediated by an attractiveness halo effect, it wouldpose difficulties for a ‘‘good genes’’ explanation of the attractiveness–symmetry relation-ship (see Feingold, 1992; Langlois et al., 2000 for meta-analytic reviews of research onattractiveness halo effects).It has been reported that manipulating digital face images so as to increase symmetryengenders an increase in ratings of apparent health (Rhodes, Zebrowitz, et al., 2001). Thisfinding suggests that symmetry is a cue to judgements of health. If the processing ofsymmetry by the perceptual system is an adaptation facilitating discrimination betweenpotential mates on the basis of apparent health (Møller & Thornhill, 1998 ), a strongadaptationist position might predict an opposite-sex bias in sensitivity to facial symmetry.In contrast, no such bias is predicted by accounts claiming that symmetry is found attractiveas a by-product of the ease with which the recognition system can process symmetric stimuli(e.g., Bradbury & Vehrencamp, 1998; Enquist & Arak, 1998; Enquist & Ghirlanda, 1998).Consistent with the strong adaptationist position, Little, Burt, Penton-Voak, and PerrettB.C. Jones et al. / Evolution and Human Behavior 22 (2001) 417–429418(2001) report that manipulations of symmetry have a greater impact on attractiveness ratingsof opposite-sex faces than ratings of own-sex faces. As yet, there have been no reported testsfor such a bias when judging apparent health.Two studies are reported here that explore predictions about the relationship betweenfacial symmetry and judgements of apparent health that arise from the ‘‘good genes’’explanation of attractiveness.2. Study 1In Study 1, the interplay between measured facial symmetry, judgements of apparenthealth, and judgements of attractiveness was explored within a partial correlation design. The‘‘good genes’’ explanation of attractiveness predicts