Genetics of Facial Masculinity 7 facial attractiveness,so a man who chooses a feminine suggested that male facial masculinity may be a signal for mate would increase the attractiveness of his daughters with no the ability to compete intrasexually for resources or nt to hi sons attrac s(although DeBruine,Jones,201 Puts,2010 or in ter of mess ad s caveats already noted)Unlike masculine male face Eaton,2013:Little,2013).but the findings ted her feminine female faces are robustly preferred across stud- call into question the predominant theoretical framework ies and have been shown to be even more strongly pr that explains preferenc masculine face high of pat DeBruine et al 2011)which pethans sugg ests a patho Author Contributions gen-related advantage of feminine faces.All this warrants The more choice of facially feminine study concept was developed by A.J.Lee. B.P.Zietsch ect or indirect (genetic)ben efits nd M.C.Kell A potential limitation of our study is that the facial and B.P.乙 photographs of twins were taken when they were 16 de wever,t hold Acknowledgments older sample.First facial dimensions are more than 94 of their adult sizes by age 16 in both sexes (Edwards et We thank our twin sample for their participation:Ann Eldridge Park,Maura Cattre al 2007).Second,there was no n in effe on m sure in the pp and David Smyth for infom ation technology n an earlier drat derived from the 16-e old twins discriminated the sexes equally well in the 18-year-old siblings.Finally,cor Declaration of Conflicting Interests relations between the twins Funding modeling could have overestimated additive genetic effects and underestimated shared environmental and nonaddi tive ger (Grants the atter twe A7960034 A7990658 A79801419.DP021201G DP109500 an twins (Keller Coventry.2005:Keller.Medland.D on 79913 and th (Grants900536.930223. 2010).Future research could overcome this problem by 950998,981339,983002,961061 830 13608 including other members of twins'families,especially parents orted by a Discovery Early Career Research Award,both arch Counci research showing greater preference for masculine faces Supplemental Material in,for example contexts of disease threat (DeBruine .c 2010;Little, DeBr e gphoomeApnoundathp/p nal dire References rather than indirect (genetic)benefits for example part. Bonduriansky,R.,Chenoweth,S.F.(2009).Intralocus sexual ners that possess markers of good health due to immuno be h would ey are ly to succ ity Press D. ial offspring (Tybur Gangestad,2011).Other authors have on offspring.Animal Bebaviour,76,1843-1853Genetics of Facial Masculinity 7 facial attractiveness, so a man who chooses a feminine mate would increase the attractiveness of his daughters with no detriment to his sons’ attractiveness (although there could be disadvantages in terms of body morphol￾ogy or behavioral assertiveness—the corollary of the caveats already noted). Unlike masculine male faces, feminine female faces are robustly preferred across stud￾ies and have been shown to be even more strongly pre￾ferred after exposure to pathogen cues and by men with high levels of pathogen sensitivity (Lee et al., 2013; Little, DeBruine, et al., 2011), which perhaps suggests a patho￾gen-related advantage of feminine faces. All this warrants more research into males’ choice of facially feminine women and the possible direct or indirect (genetic) ben￾efits to offspring. A potential limitation of our study is that the facial photographs of twins were taken when they were 16 years old, at which time facial masculinity might not yet have fully developed. However, the following observa￾tions suggest that the findings would probably hold in an older sample: First, facial dimensions are more than 94% of their adult sizes by age 16 in both sexes (Edwards et al., 2007). Second, there was no mean effect of age on the facial masculinity measure in the sample including older siblings. Third, the facial masculinity measure derived from the 16-year-old twins discriminated the sexes equally well in the 18-year-old siblings. Finally, cor￾relations between the twins and older siblings showed the same pattern as correlations within the twins. Other limitations of our study include standard caveats of the classical twin design. In particular, our biometrical modeling could have overestimated additive genetic effects and underestimated shared environmental and nonaddi￾tive genetic effects, because the latter two effects are nega￾tively confounded when they are estimated using only twins (Keller & Coventry, 2005; Keller, Medland, & Duncan, 2010). Future research could overcome this problem by including other members of twins’ families, especially parents. Assuming that our results are generalizable, how might we explain the findings in light of the aforementioned research showing greater preference for masculine faces in, for example, contexts of disease threat (DeBruine, Jones, Crawford, et al., 2010; Little, DeBruine, et al., 2011)? It has recently been suggested that male facial masculinity may signal direct benefits (Scott et al., 2012) rather than indirect (genetic) benefits. For example, part￾ners that possess markers of good health due to immuno￾competence may be preferred because they are less likely to succumb to disease, which would decrease their resource-provisioning ability and increase the likelihood that they will transfer disease to their partners or mutual offspring (Tybur & Gangestad, 2011). Other authors have suggested that male facial masculinity may be a signal for the ability to compete intrasexually for resources or mates (Little, DeBruine, & Jones, 2012; Puts, 2010; Scott et al., 2012). How these various explanations might be distinguished has not been fully resolved (Gangestad & Eaton, 2013; Little, 2013), but the findings reported here call into question the predominant theoretical framework that explains preferences for males with masculine face shape in terms of genetic benefits for offspring. Author Contributions The study concept was developed by A. J. Lee, B. P. Zietsch, and M. C. Keller. Data collection was executed by N. G. Martin, M. J. Wright, D. G. Mitchem, and M. C. Keller. A. J. Lee and B. P. Zietsch performed the data analysis and interpretation. A. J. Lee and B. P. Zietsch drafted the manuscript, and all other authors provided critical revisions. All authors approved the final version of the manuscript for submission. Acknowledgments We thank our twin sample for their participation; Ann Eldridge, Marlene Grace, Kerrie McAloney, Daniel Park, Maura Caffrey, and Jacob McAloney for photograph collection and processing; David Smyth for information technology support; and Bill von Hippel and Patrik Jern for helpful comments on an earlier draft. Declaration of Conflicting Interests The authors declared that they had no conflicts of interest with respect to their authorship or the publication of this article. Funding We acknowledge support from the Australian Research Council (Grants A7960034, A79906588, A79801419, DP0212016, DP0343921, DP0664638, DP1093900, and FT0991360) and the Australian National Health and Medical Research Council (Grants 900536, 930223, 950998, 981339, 983002, 961061, 983002, 241944, 389875, 552485, and 613608). A. J. Lee is sup￾ported by an Australian Postgraduate Award, and B. P. Zietsch is supported by a Discovery Early Career Research Award, both from the Australian Research Council. Supplemental Material Additional supporting information may be found at http://pss .sagepub.com/content/by/supplemental-data References Bonduriansky, R., & Chenoweth, S. F. (2009). Intralocus sexual conflict. Trends in Ecology & Evolution, 24, 280–288. Bookstein, F. L. (1991). Morphometric tools for landmark data. Cambridge, England: Cambridge University Press. Cornwell, R. E., & Perrett, D. I. (2008). Sexy sons and sexy daughters: The influence of parents’ facial characteristics on offspring. Animal Behaviour, 76, 1843–1853. Downloaded from pss.sagepub.com by Cai Xing on January 7, 2014