In view of disease risk, Kong et al. (2012) demonstrated that most of the new mutations are explained by the age of the father at conception. Accordingly, paternal age effects have been found for a variety of offspring traits, from physical and mental health to intelligence. Here, we investigated whether facial attractiveness is significantly associated with paternal age. We used the Wisconsin Longitudinal Study (n = 4018 male and 4416 female high school graduates) to analyze the association between an individual's father's age at birth and that individual's facial attractiveness (estimated by rating the high school yearbook photographs from 1957), controlling for sex, age as well as mother's age. We find that subject's facial attractiveness decreased with advancing paternal but not maternal age, suggesting that facial attractiveness might be a cue of an individual's new mutation load.
In recent years, growing evidence shows that advanced paternal age at conception is linked with an increased risk of a wide range of neuropsychiatric disorders, including schizophrenia (Brown et al., 2002, Malaspina, 2001 and Sipos et al., 2004), autism spectrum disorder (Hultman et al., 2011 and Reichenberg et al., 2006), bipolar disorder (Frans et al., 2008), and epilepsy (Vestergaard, Mork, Madsen, & Olsern, 2005) as well as Mendelian disorders (Crow, 2000) and aspects of physical health (Bray, Gunnell, & Smith, 2006). Higher paternal age also predicts lower intelligence (Cannon, 2009) and a higher risk of obesity (Eriksen, Sundet, & Tambs, 2013). This association of higher risk for disease and paternal but not maternal age is explained by the fact that women are born with their full supply of eggs, whereas men continue with sperm production throughout reproductive life (Crow, 2000). In the egg, all cell divisions are completed before birth, whereas the number of cell divisions and chromosome replications that sperm cells have gone through increase with the age at which the sperm is produced. As a consequence, a sperm undergoes many more germline cell divisions than an egg, the difference increasing with advancing age (Crow, 2000). Accordingly, Kong et al. (2012) demonstrated that a much higher number of mutations are transmitted by the father than the mother to their children, and that it is the age of the father which explains nearly all of the new mutations in a child.
A vast body of work has been published about cues, preferences and significance of facial attractiveness (e.g., Fink and Penton-Voak, 2002, Hume and Montgomerie, 2001, Rhodes, 2006, Thornhill and Gangestad, 1999 and Weeden and Sabini, 2005). Only little is known, however, about whether facial attractiveness has a genetic basis. Yet, two very recent papers by Mitchem et al. (2013) and Lee et al. (2013) showed heritable genetic influences on facial attractiveness, and Liu et al. (2012) reported on 5 genes influencing facial morphology.
This is the first study investigating whether facial attractiveness is associated with the father's age at conception, which would suggest that new mutations in the father's sperm are expressed in offspring attractiveness. This view is in line with mutation-selection balance theory and fitness-indicator theory. Mutation-selection balance theory proposes that a balance of forces between constantly arising mildly harmful mutations and selection causes variation in genetic quality and phenotypic condition (Keller, 2008 and Miller, 2000). Mutation-selection balance is assumed to be particularly important in traits influenced by many genetic loci; this assumption is reasonable for a complex trait such as facial attractiveness because these traits provide a larger target size for mutations (Keller, 2008). Fitness indicator theory proposes that traits can function as reliable indicators of an individual's genetic quality and/or phenotypic condition. A fitness indicator serves as a signal of viability, fertility as well as genetic quality in terms of low mutation load and low genetic inbreeding, to potential mates, rivals, or allies (Arden et al., 2009, Haselton and Miller, 2006 and Keller, 2008). Reliable fitness indicators cannot be faked because they are costly and demonstrate an ability to resist perturbations by genetic mutations and/or environmental hazards (Sefcek, Brumbach, Vasquez, & Miller, 2007).
In view of these hypotheses, we would expect that facial attractiveness is sensitive to mutations, and we therefore predict that facial attractiveness should decline with paternal age at conception. We analyzed the association of an individual's father's age at birth and that individual's facial attractiveness, controlling for sex, age as well as mother's age. We used the Wisconsin Longitudinal Study for these analyses because it is one of the most comprehensive longitudinal studies tracing the life of several thousand individuals. Moreover, the suitability of this dataset for research on attractiveness has been recently demonstrated (Jokela, 2009).
