“What is beautiful is good,” wrote Sappho, a lyric poet who lived on the island of Lesbos in the sixth century BCE.
From Pythagoras to Plato, the ancients assumed beauty conformed to objective rules and was correlated with virtue, intelligence, and divine favor.
Feminist author Naomi Wolf conversely argued that beauty has no objective or universal attributes. To Wolf, beauty was simply a myth harnessed by the patriarchy to fuel a capitalist agenda and perpetuate male dominance.
Humans are inherently “lookist,” and mercantile incentives do influence our conception of the human ideal. Beauty is the engine behind vast swaths of entertainment, advertising, and the $49 billion cosmetics industry.
Our conception of beauty today is also highly politicized and culturally fraught. Some narratives suggest that beauty exists only “in the eye of the beholder.” Many intellectuals argue that beauty is scientifically inconsequential.
But there are measureable aspects of human appearance, mating habits, and cultural conventions that lend themselves to scientific study. And there are universal beauty ideals across cultures.
Charles Darwin was the first to propose that competition for mates plays an important role in reproductive success – a process he dubbed “sexual selection.” Darwin hypothesized that any trait that gives a male mating advantages will spread in a population because males with such traits will have more offspring.
Darwin’s more famous theory, “natural selection,” differs from sexual selection in important ways.
All the Galapagos Finches that Darwin categorized descended from a single ancestor, but each species evolved a different beak shape that was optimized for the most abundant food type on their particular island.
There are only a finite number of beak shapes to choose from, but the number of mutations that might evolve into avian mating ornaments is limitless.
Sexual ornaments are aesthetic traits that evolve as a result of choices made by generations of mating partners. The subjective evaluations of prospective mates determine who has more offspring, leading certain traits to outcompete others.
Unlike natural selection, this process is inherently collaborative. Procreation is a cooperative venture between two rival sets of genes.
In many dimorphic species, biologists can identify that one gender is more “choosy” and that the other is more often “chosen.”
The chosen gender will typically evolve greater sexual ornamentation. Those adaptations often have no utility to the individual, but they do signal genetic virtues to a potential mate.
For example, peacocks evolved their vibrant tail plumage not because it improved their survival odds, but because peahens interpret the colorful display as a signal of health. Peahens, the choosy gender, are brown and quite drab compared to their mates.
Testosterone, the elixir of masculinity among humans, likewise increases susceptibility to infectious disease, which should be maladaptive. But it also serves to express a range of sexual ornaments among males at the onset of puberty.
Boys’ voices deepen, their skin darkens, their muscle mass increases, and their faces acquire dominant jaws and brow ridges. The more competitive nature of men, which is also correlated with testosterone, is therefore actually a consequence of sexual selection.
In her book Survival of the Prettiest, Nancy Etcoff compiled universal aspects of human beauty that have been identified within the fields of biology, anthropology, and psychology.
Every culture studied considers looks an important criterion in a mate, though men consistently place a greater value on appearance than women.
We all universally associate symmetrical features with attractiveness, because it is a proxy for fitness.
Taller men are perceived to be more masculine, attractive, and high status. In actual salary data, height is strongly correlated with higher pay. Among married hetero couples, only 0.3% of women are taller than their husbands.
Firm, upward tilting breasts have long been associated with beauty among women because ornamentally they mimic the physiology of nubile girls, who have the greatest reproductive capacity.
Female décolletage became a fashion fixture during the Renaissance, a time when wealthy women hired wet nurses to feed their babies. An estimated 90% of women in this era were milk bearing; having a wet nurse was a status symbol.
Portraits of the time show elite women with high, rounded breasts above tight corsets. Corsets helped accentuate the hourglass shape that is also a signal of beauty among women.
A study of body shape perceptions among 18 different cultures found that men universally view a dramatic hourglass shape (a waist to hip ratio of 0.7) as most attractive. Fertility studies have also confirmed that a lower waist to hip ratio (0.8 or below) actually does increase a woman’s probability of getting pregnant.
Capitalism is accused of fomenting our obsession with physical appearance. However, one study demonstrated that the prevalence of parasitic diseases (not exposure to supermodels) was a key factor determining how much a culture values physical beauty in a mate.
Like Sappho, we expect attractive people to be better at everything. We guess that their marriages are happier; that their jobs are better, and even assume their mental health is superior.
In The Red Queen: Sex and the Evolution of Human Nature, author Matt Ridley details how evolutionary anthropologists now posit that human intellect itself is a product of sexual rather than natural selection. It seems big brains really are sexy, and may have evolved as a result of sexual competition.