For most of the past century, mainstream social scientists have assumed that attractiveness is superficial, arbitrary, and infinitely variable across cultures. Many still cling to these views. Their appeal has many motivations. First, beauty is undemocratically distributed, a violation of the belief that we are all created equal. Second, if physical desirability is superficial ("you can't judge a book by its cover"), its importance can be denigrated and dismissed, taking a back seat to deeper and more meaningful qualities. Third, if standards of beauty are arbitrary and infinitely variable, they can be easily changed.
Two movements in the 20th century seemed to lend scientific support for these views. The first was behaviorism. If the content of human character was built through experienced contingencies of reinforcement during development, those contingencies must have created standards of attractiveness. The second was seemingly astonishing ethnographic discoveries of cross-cultural variability in attractiveness. If the Maori in New Zealand found particular types of lip tattoos attractive and the Yanomamo of the Amazon rain forest prized nose or cheek piercings, then surely all other beauty standards must be similarly arbitrary.
The resurgence of sexual selection theory in evolutionary biology, and specifically the importance of preferential mate choice, created powerful reasons to question the theoretical position long held by social scientists. We now know that in species with preferential mate choice, from scorpionflies to peacocks to elephant seals, physical appearance typically matters greatly. It conveys critical reproductively valuable qualities such as health, fertility, dominance, and 'good genes.' Are humans a bizarre exception to all other sexually reproducing species?
Evolutionary theorizing, long antedating the hundreds of empirical studies on the topic, suggested that we were not. In mate selection, Job One, as someone in business might say, is the successful selection of a fertile partner. Those who failed to find fertile mates left no descendants. Everyone alive today is the product of a long and literally unbroken line of ancestors who succeeded. If any had failed at the critical task, we would not be here today. As evolutionary success stories, each modern human has inherited the mate preferences of their successful ancestors.
Cues recurrently observable to our ancestors that were reliably, statistically, probabilistically correlated with fertility, according to this theory, should become part of our evolved standards of beauty. In both genders, these include cues to health—symmetrical features and absence of sores and lesions, for example. Since fertility is sharply age-graded in women, more so than in men, cues to youth should figure prominently in gender-specific standards of attractiveness. Clear skin, full lips, an unclouded sclera, feminine estrogen-dependent features, a low waist-to-hip ratio, and many other cues to female fertility are now known to be pieces of the puzzle of universal standards of female beauty.
Women's evolved standards of male attractiveness are more complex. Masculine features, hypothesized to signal healthy immune functioning in men, are viewed as attractive more by women seeking short-term than long-term mates, more when women are ovulating than when in the luteal phase of their menstrual cycle, and more by women higher in mate value, perhaps because of their ability to attract and control such men. Women's judgments of men's attractiveness are more dependent on multiple contexts—cues to social status, the attention structure, positive interactions with babies, being seen with attractive women, and many others. The greater complexity and variability of what women find attractive in men is reflected in another key empirical finding—there is far less consensus among women about which men are attractive than among men about which women are attractive.
The theory that 'beauty is in the eyes of the beholder' in the sense of being superficial, arbitrary, and infinitely culturally variable can safely be discarded. I regard it as one of the 'great myths' perpetrated by social scientists in the 20th century. Its scientific replacement—that beauty is 'in the adaptations of the beholder' as anthropologist Donald Symons phrases it—continues to be disturbing to some. It violates some of our most cherished beliefs and values. But then so did the notion that the earth was not flat or the center of the universe.