Presidents’ Award Putting beauty back in the eye of the beholder ANTHONY LITTLE and DAVID PERRETT (winner of the 2000 Presidents’ Award for Distinguished Contributions to Psychological Knowledge) discuss evolution and individual differences in face preference. UR magazines and television This problem with considering beauty evolutionary theory, which posits that the screens are filled with images as only in the eye of the beholder is nicely attractiveness of individuals is directly O of ‘attractive’ people, and it is illustrated in Figure 1. Here, the two faces linked to their value as mates. High-value obvious that both women and men are are both symmetric and have perfectly mates are those who can best enhance the highly concerned with good looks in smooth skin, yet the composite on the right reproductive success of the individual who a partner. But exactly what is it that makes made from the faces of 50 models is chooses them. Individuals who were a face beautiful? What makes people seek systematically different from the composite attentive to cues to high mate-value, and out and desire to mate with the owners of student face in both shape and coloration. based mate-choice decisions on these cues, beautiful faces? Most people will agree it is more attractive. left behind more offspring (and so more It is difficult to verbalise what Some people are beautiful and some people genes for attending to attractive cues) than differentiates average from good-looking are not, and most people agree on who is those who failed to attend to these cues. individuals, and in modern times there is and who is not beautiful. Such evolutionary reasoning can also be a pervasive view that attractiveness simply Agreement between individuals is in applied to humans. In essence, the cannot be defined. Common phrases such fact one of the best-documented and most evolutionary view suggests that when as ‘beauty is in the eye of the beholder’ and robust findings in facial attractiveness making attractiveness decisions we are all, ‘beauty is only skin deep’ are testaments to research since the 1970s. Across many albeit unconsciously, asking the question our belief that attractiveness is ephemeral. studies it has been found that there is ‘What can the owners of beautiful faces do For example, the philosopher David Hume a high degree of agreement from for us in order that our genes survive to is often quoted for making the argument individuals within a particular culture, and subsequent generations?’ that beauty ‘is no quality in things high agreement between individuals from In many studies this evolutionary view themselves: it exists merely in the mind different cultures (see Langlois et al., 2000, of attractiveness has been powerful in which contemplates them; and each mind for a meta-analytic review). If different predicting the specific characteristics of contemplates a different beauty’ (Hume, people can agree on which faces are attractive faces (see Thornhill & 1757, p.208–209). attractive and which faces are not attractive Gangestad, 1999, for a review). A central But something in this politically when judging faces of varying ethnic tenet of the evolutionary view is that correct view of beauty just does not ring background, then this suggests that people individuals should agree on the true. Admittedly the latest big movie star everywhere are all using the same, or at characteristics that make up attractiveness is not everyone’s favourite pin-up; but it is least similar, criteria in their judgements. (e.g. Langlois et al., 2000). For example, undeniable that on average Hollywood males who preferred women past stars are generally more attractive than Evolution and attractiveness reproductive age would not have left their the people we meet in the street. You may Physical appearance is important to genes in the next generation and so we disagree over your best friend’s choice of humans and there appear to be certain partner but there are countless individuals features that are found attractive across FIGURE 1 that you and your friend could agree were individuals and cultures. The same holds more or less attractive than the particular true across the animal kingdom: most partner. non-human species rely on external factors, such as the sizes, shape and colour of adornments (e.g. feathers, fur, and fins) to attract mates. Research on animals has WEBLINK focused on individual traits that are For information on experiments and to attractive across individuals (and even participate in ongoing research: species) such as symmetry (e.g. Møller www.perceptionlab.com & Thornhill, 1998). Such experiments are driven by 28 The Psychologist Vol 15 No 1 January 2002 Presidents’ Award might expect a universal preference for FIGURE 2 assortative mating occurs when individuals youth in males. form pairs in which the individuals Proposed universal preferences are involved are more similar to each other consistent with the cross-cultural than would be expected by chance (Burley, agreement on attractiveness. For example, 1983). In humans, mating with similar youth, which is associated with fertility and individuals to oneself may have genetic the potential for offspring production in benefits. For example, Thiessen and Gregg women, has been found to be attractive in (1980) have proposed that mating with faces across individuals and cultures (Buss, similar-looking individuals increases the 1989). We will now look in more detail at chances that those individuals have genes another example of a universal in common with you, and that mating with characteristic of beauty and its proposed such individuals can be advantageous to evolutionary root. your genes. Of course the advantages of mating with similar individuals has its Facial symmetry limits. Mating with your close family Research on symmetry has been may be a range of mating strategies members is referred to as inbreeding, conducted on many animal species and that can be employed based on both which reduces genetic diversity and provides a good example of a characteristic environmental cues and individual physical increases the chances of harmful recessive of human faces that is proposed to be attributes. In humans, whilst individuals genes being expressed in offspring. The attractive across observers. Symmetry may share certain basic criteria for finding best strategy might be to avoid mating with refers to the extent that the left half of an faces attractive, many factors may close relatives but to mate with someone organism is the same as the right. It is influence the specific types of face they genetically more similar to you than a significant characteristic, as it can be seen find attractive. average. Bateson (1982) called this notion as a measure of the ability of an organism optimal outbreeding and demonstrated its to cope with environmental stress (e.g. food Look-alikes occurrence in Japanese quail. Birds of both scarcity): the optimal developmental It is a widespread belief that partners look sexes were attracted to first cousins over outcome for most characteristics is alike (e.g. the 1930 portrait by Grant Wood siblings and unrelated individuals. symmetry. Only high-quality individuals called American Gothic, below). Positive Early research on assortative mating in can maintain symmetric development under environmental and genetic stress; therefore symmetry can serve as an indicator of the quality of an individual as well as the quality of their genes (see Møller & Thornhill, 1998). For example, individuals with genes coding for strong immune function will be more resistant to infection, allowing their bodies to grow more symmetrically than individuals with lower immune capacity, who will be ‘stressed’ more by exposure to the same infection. When manipulating symmetry with computer graphics, symmetric faces are found to be preferred over less symmetric faces (e.g. the symmetric faces on the bottom row of Figure 2) (Perrett et al., 1999; Rhodes et al., 1998). Measuring symmetry in real faces reveals a positive correlation with rated attractiveness (e.g. Grammer & Thornhill, 1994; Mealy et al., 1999; Penton-Voak et al., 2001). Individual differences Having argued for the universality of attractive traits, we now examine some factors that may lead to individual differences in the perception of facial attractiveness and speculate on how such differences may arise from learning and differences in life history. Across the animal kingdom not all members of a given species engage in the same mating behaviour. Indeed, within a species there Birds of a feather? 29 January 2002 The Psychologist Vol 15 No 1 Presidents’ Award humans focused on correlations in physical Research thus suggests that awareness tendency to develop a sexual aversion to characteristics between partners, such as of one’s own traits may encourage choice individuals with whom they live closely arm length. Reviews show an overall of partners similar to oneself. Seeking out in infancy and early childhood (usually pattern of low positive correlations (0.01 a partner who is similar to you, however, is siblings and parents). Originally proposed to 0.35) for many physical features (e.g. also consistent with attraction to parental as a mechanism for avoiding sibling incest, Spuhler, 1968). Married partners’ faces also traits, as usually children physically such negative imprinting would prevent resemble each other in ways that allow resemble their parents. This leads us to inbreeding in a population. Westermarck’s them to be identified as partners, possibly consider the influence of parental hypothesis has received empirical support indicating assortative mating for similar characteristics on mate preferences in from ethnographic studies where male and face shapes (e.g. Hinsz, 1989). humans. female non-siblings are raised together in Partners also appear to assort for many a way similar to real siblings (e.g. Shepher, non-physical traits such as religion, Attraction to parental traits 1971). Such individuals avoided marriage educational level and personality (Botwin In humans there have been few studies on or sexual relations with those with whom et al., 1997; Thiessen & Gregg, 1980).