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An Evolutionary Perspective on Physical Attractiveness

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An Evolutionary Perspective on Physical Attractiveness Evolutionary Anthropology 97 An Evolutionary Perspective on Physical Attractiveness DOUG JONES Everyday experience suggests that physical attractiveness is important in per- to others, and that mate choices based sonal-and especially sexual-relationships. This impression is confirmed by a on these preferences have evolution- large body of social psychological research.’ z2 Cross-cultural surveys and ethno- ary consequences. However, he did graphic accounts show that concern with the attractiveness of potential mates is not take up the question of where pref- also common in non-Westernsocietiesand in tribal and peasant cultures3 However, erences come from in the first place - social psychologists and anthropologists have often had a hard time explaining why e.g., why peahens prefer peacocks attractiveness should count for so much, or why some features rather than others with large and showy trains. In recent should seem particularly attractive. The theoretical difficulties in accounting for work on sexual selection and mate physical attraction are brought out in a Brazilian saying, “Beleza n2o p6e na mesa” choice,6,7 this question occupies a cen- (“Good looks don’t put anything on the table”), which points to the absence of any tral place. This work asks how natural evident practical advantage to choosing an attractive mate. Faced with these diffi- selection might affect mating prefer- culties, a growing number of researchers in biology, psychology, and anthropology ences and why one set of mating pref- have turned to the modern theory of sexual selection, which has been highly suc- erences might lead to greater cessful in explaining nonhuman animals’ attractions to traits of no direct ecological reproductive success than another. utility. In this article, I survey recent efforts to apply the theory of sexual selection to From this perspective, mate choice is human physical attraction. seen as being guided by adaptations having the function of assessing the “matevalue”of potential mates, where Sexual selection occurs when some train of the peacock. He argued that mate value is the expected reproduc- individuals have characteristics that mate choice provides one avenue for tive success from mating with a given lead them to succeed in mating and the operation of sexual selection: individual relative to mating ran- fertilization at the expense of others of Traits without value in the struggle for domly or relative to some other base- their sex. Darwin, in On the Origin of existence might nonetheless persist in line reproductive success. Species4 and The Descent of Man and a population if they were attractive to This adaptationist approach to Selection in Relation to Sex,5 intro- members of the other sex and resulted mate preferences has several limita- duced the concept of sexual selection in more or better matings for carriers tions. Mate preferences are likely to be and argued that it had been important of these traits. The theory of sexual se- affected not only by adaptations for in shaping traits of no obvious value in lection via mate choice met with a cool assessing mate value, but by nonadag the struggle for existence, like the ant- reception in Darwin’s time, and played tive sensory and cognitive biases. Fur- lers of the stag and the extravagant little role in the Modern Synthesis of thermore, mate value may have an the 1930s and 1940s that united Dar- arbitrary component: Owing to the se- winian evolutionary theory and the lective benefits of having attractive new science of genetics. But the period offspring, it may be adaptive for indi- Doug Jones has carried out research from the 1970s to the present has seen viduals to adopt even idiosyncratic lo- comparing standards of physical an explosion of theoretical and em- cal mate preferences, provided these attractiveness in the United States, Brazil, Paraguay, and Russia. He is the author of pirical investigation that has strongly are both heritable and shared by the Sexual Selection, Physical Attractiveness vindicated Darwin’s interest in the rest of the population. Hence, the pre- and Facial Neoteny: Cross-Cultural topic. The modern literature on sexual dictive power of an adaptationist ap- Evidence and Implications, published in Current Anthropology, and Physical selection is reviewed at book length by proach may be limited. Nevertheless, Attractiveness and the Theory of Sexual Anderson6 and, in a more popular this approach is one of the most pow- Selection: Results from Five Populations, published by the University of Michigan vein, by Cr~nin.~ erful theoretical tools at our disposal, Museum of Anthropology. His future The theory of sexual selection as it and has considerable explanatory research will focus on the life-history has developed since the 1970s differs power even when organisms behave consequences of being attractive or unattractive. from Darwin’s theory in at least one maladaptively or in response to idi- important respect. Darwin was par- osyncratic local selection pressures. ticularly concerned to show that or- In this review of recent empirical Key words: Sexual selection, mate value, neoteny, fluctuating asymmetry, social learning ganisms prefer some potential mates and theoretical work applying the 98 Evolutionary Anthropology ARTICLES TABLE 1. Adaptive Problem Relevant Physical Cues Possible Evolutionary Consequences Assessing the fecundity of a potential mate. Waist-to-hip ratio Fat deposition in female hips, buttocks, and (Among humans, this is a particular problem thighs, exaggerating low waist-to-hip ratio for males, given high age-related variability Facial propoflions Facial neoteny (especially in females, and in aduit female fecundity.) especially in populations where a large proportion of females survive past menopause) Skin color Reduced pigmentation (especially in females, and especially in climates where ecological costs of reduced pigmentation are low) Assessing the general health and parasite load Fluctuating asymmetry Structures specialized to advertise symmetry of a potential mate. (Health and parasite Anemia Structures specialized to advertise absence of load are likely to affect a mate‘s fecundity anemia (e.g. everted lips) and provisioning ability, and may correlate with genetic load.) Assessing mate value in the face of variation Average features Stabilizing selection preserving local or regional between populations in morphology, variants clothing, and adornment, selection Features favored by other Divergent selection exaggerating local or pressures, and correlates of mate value. population members regional variants modern theory of sexual selection to sessing the fecundity of potential the expected reproductive success human physical attraction, I will ad- mates. from a short-term mateship with a dress several questions: What major Two distinctive features of human partner of a given age, divided by the adaptive problems do humans face in reproduction are likely to be especially expected reproductive success from a assessing the more value of a potential important to understanding the rele- short-term mateship with a random mate? What physical cues reliably af- vance of fecundty to attractiveness in adult of the other sex. This figure ford information relevant to solving our species. First, in contrast to many shows that there is much more age-re- these problems? and What are the evo- primate species in which ovulation is lated variance in female than in male lutionary consequences of mate signaled by visual, olfactory, or behav- fecundity. In fact, given an age struc- choice? Three sections of this paper ioral cues, human females do not ad- ture realistically associated with a life take up adaptive problems, including vertise ovulation. Cues to female expectancy at birth of 35 years and evaluating the fecundity and the over- fecundity in our species track long- zero population growth, age-related all health and parasite load of a poten- term variations rather than short- variance in fecundity is almost 10 tial mate and allowing for local term, cyclical ones. Second, human times greater in adult females than variation in morphological cues and females, in contrast to most other pri- adult males. Consequently, there will selection pressures. A final section mate females (as well as human be much stronger selection on males considers the possible consequences males), experience major changes in than females to choose partners on the of mate preferences for the evolution fecundity before and during meno- basis of age. of human morphology. Adaptive prob- pause. Female fecundlty declines sig- It is also possible to use agelfecun- lems, relevant physical cues, and pos- nificantly after age 35 and falls to zero dity curves, in conjunction with sible evolutionary consequences are between ages 45 and 50, while a sub- agelmortality curves, to construct summarized in Table 1. stantial fraction of women commonly curves of “long-term mate value”’* live well past this age even under pre- that measure expected reproductive FECUNDITY AND AGE modern demographic regimes8z9 success in a mateship lasting until the The mate value of potential mates Figure 1 shows how marital fertility death of one partner relative to repro- will depend on their fecundity (the changes with age for females and ductive success from mating ran- likelihood that mating will result in males in natural fertility (noncontra- domly. Long-term mate value depends conception and the birth of offspring); cepting) populations, based on data on the age of both partners: a 30-year-
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