[Intricate peacock feathers provoked Charles Darwin’s theory of sexual selection.]

Bird by bird, new book explores Darwin’s theory of mate selection.

The Evolution of Beauty: How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World—and Us by Richard O. Prum. Doubleday, 540 pp.

Giving a friend a tour of Otterbein University recently, my wife and I guided her into its Science Center, mostly so I could re-visit its plexiglass aviary of parakeets just off the lobby. A subject of study by faculty and students, the birds, of the sort sold in countless pet shops, are native to Australia and are properly called budgerigars. Otterbein’s dozen budgies flit about in an array of colors and patterns: traditional greens, spritely blues, luminescent yellows.

“These birds all look different,” I said to our guest. “But all of them have something in common. Can you see it?”

A mathematician, she accepted this empirical challenge and circled the aviary. The birds took scant notice, accustomed to visitors. After she gave up, I said, “They’re all males.” The only giveaway is that, in the traditional patterns, males have a vivid blue cere, a patch of flesh, above their beaks.

Thus the chance to explain that Otterbein academics have duplicated a fraternity house—because a female-only budgie flock would fight. (And surely all hell would break loose if the academics had mixed males and females.)

“But why do they make that noise?” she asked me. “What are they saying?”

We listened to the birds’ chortling—an endless, repetitious but pleasing boy chorus. Why indeed? A traditional survival-of-the-fittest answer: they’re claiming territory. A prelude to war. But surely the best answer—and equally Charles Darwin’s—is: because female parakeets like the sound. Furthermore, they’re favoring males who are sociable enough to flock together to produce such background sound for them to enjoy.

The latter answer isn’t my Romantic notion but arrives courtesy of an important new book, The Evolution of Beauty: How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World—and Us. Its author, Richard O. Prum, a Yale-based ornithologist, previously led the hypothesis that there were feathered dinosaurs. Maybe not the biggest news, to anyone who has seriously looked at a chicken. But thanks, all the same, for the concept that you’ve got dinosaurs in your coop.

A quick review here. By now we’ve all imbibed Darwin’s concept of natural selection. Animals assume their shapes and behaviors under environmental pressure—the gazelle that can outrun and dodge the leopard gets to procreate, etc. Explained in Darwin’s first book, On the Origin of Species, in 1859, this theory upended the scientific world. No God anymore, just nature, “red in tooth and claw,” as Tennyson put it. Some say this theory cracked the foundation of the church. Eventually it helped Ayn Rand inflict her stunted vision upon teenagers and the weak minded.

But after his first revolutionary theory, Darwin worked out a second and somewhat contradictory stunner. It started with his thinking about the peacock’s tail. He famously told a friend that its feathers made him ill. Such an ornament simply could not be a mere billboard proclaiming fitness. Sure, the tail’s breadth, length, and heft indicate that the male bearing it must be a sturdy fellow. But look at the tail’s intricate, artistic, colorful design. Females had to select for that, Darwin realized. He started studying and theorizing about the evolutionary effect of mate selection. He broached this notion in his second book. The Descent of Man, and Selection in Relation to Sex, in 1871.

As Prum explains, Darwin’s fellow Victorian scientists, to a man, reacted with outrage. How could a peahen—or any other bird-brained female—drive evolution? Their unrelenting sexist campaign seriously damaged the spread and acceptance of Darwin’s second great theory.

Evolutionary scientists since then have likewise rejected or minimized sexual selection’s role in shaping animals. The current reasons are less clear. Maybe we can intuit from one of their contemporary leading lights, the author of The Selfish Gene, Richard Dawkins, who believes all human behavior flows unconsciously from programming aimed at furthering our own genetics. As if that isn’t dreary enough, Dawkins bruits his religion—a giddy militant atheism—far and wide. Dawkins and his ilk have inherited from Darwin’s Victorian gatekeepers a paradigm that explains everything. Case closed. Easy peasy. But to admit that creatures possess agency to shape themselves—where did that come from? Suddenly they’re cheek by jowl with poetry and religion, whose turf is . . . mystery.

Beauty is truth, truth beauty,—that is all

Ye know on earth, and all ye need to know.

—John Keats, “Ode on a Grecian Urn”

[Richard O. Prum, Yale ornithologist and evolutionary psychology provocateur.]

Explaining the rise of the global human patriarchy.

The payoff of Prum’s argument starts more than halfway through The Evolution of Beauty, as he teases out the implications of aesthetic evolution for our own species. In short, as with birds, men and women created each other—physically, intellectually, emotionally.

But if it’s true that our hominin foremothers began domesticating males millions of years ago— especially selecting for those who’d help rear children—and then handed the torch to Homo sapiens women 200,000 years ago, what has happened?

How arose patriarchy and other forms of sexism, plus homophobia and oppressive totalitarian and reactionary politics? Prum’s answer: two cultural innovations, agriculture and the market economy that arose with it, some 15,000 years ago. Farming again, alas, as The Fall. The Bible broke this story thousands of years ago. So the consensus remains: farming permitted humans, for the first time, to achieve wealth and to amass it variably.

Goodbye to the Garden of Eden. Hello to farms and cities—to the risen glory of human civilization. And to having to earn our bread in the sweat of our faces. Prum:

When males gained cultural control over these material resources, new opportunities were created for the cultural consolidation of male social power. The parallel and independent invention of patriarchy in many of the world’s cultures has functioned to impose male control over nearly all aspects of female life, indeed human life. Thus, the cultural evolution of patriarchy has prevented modern women from fully consolidating the previous evolutionary gains in sexual economy.

Prum doesn’t speculate on why men. I’d say the ego of Homo sapiens has something to do with it—while instantiated in both sexes, what the Bible calls “vanity” seems more strongly rooted in males. What’s ego? That which “wants and fears,” says Eckhart Tolle in his remarkable spiritual synthesis A New Earth.

[Otterbein University’s bro budgies: cheerful bachelors singing for absent gals.]

Duck sex & patriarchal rage at women and homosexuals.

[Muscovy drake: suspected rapist.]

Prum builds his case bird by bird. Fascinating stuff—the plumage, displays, and temperaments that female birds have selected for. The males they’ve created boggle the mind. All the same, like me, you may skim here. Except it’s important to absorb enough detail to grasp the implications. Which aren’t all sunny. In ducks, females have evolved convoluted reproductive systems to thwart insemination by rapist drakes. As a lifelong poultry keeper, I’ve seen avian love—as well as roosters who rape hens (and ducks, for that matter). And there was my infamous drake, name of Mad Jack Percival, whose barnyard tenure ended early because he raped hens . . .

But the lion’s share of sexual selection, as it were—and therefore of autonomy—goes to the lioness, in Prum’s view. For example, here’s Prum’s take on human male homosexuality, which will be controversial: it’s a byproduct of females selecting males for greater sensitivity. Which actually makes more sense, in context, than people aping Darwin’s survival of the fittest theory who say, after Dawkins et al, that non-breeders boosted a clan’s prolificacy by providing child-rearing services.

Sensing the sexual power of women—if not their dominant role in shaping men—no wonder patriarchal ideologies are so focused on controlling female sexuality and reproduction and on condemning same-sex behaviors. But “patriarchy is not inevitable, and it does not constitute human biological ‘destiny,’” Prum writes. “Patriarchy is a product not of our evolutionary history nor of human biology per se but of human culture.”

Culture of course can and does change—witness America’s social progress in the past 50 years alone. In part, Prum believes, such pushback represents the “emergence of cultural countermeasures to reassert and preserve female sexual and social autonomy.” But he considers the war between the sexes far from over:

The concept of an ongoing, culturally waged sexual conflict arms race also allows us to understand what is at stake in the battle between contemporary feminists and advocates of conservative, patriarchal views of human sexuality. After all, control over reproduction—including birth control and abortion—is at the very core of sexual conflict.

Like the evolved sexual autonomy of ducks, feminism is not an ideology of power or control over others; rather, it is an ideology of freedom of choice. This asymmetry of goals—the patriarchal aim of advancing male dominance versus the feminist commitment to freedom of choice—is inherent in all sexual conflict, from ducks to humans. But it gives the contemporary cultural struggle over universal sexual rights an especially frustrating quality.

The centuries-long war on women—eloquently summarized by Tolle in A New Earth—along with literal wars and despots who usurp our species’ transcendent yearnings, are a global human tragedy. Prum both illuminates its causes and makes you feel that we’re not nearly at the end of our story. This thrilling book is very important. Prum offers a refreshing theory built from solid research and a mind unclouded by stale dogma. His findings and theory imply that humanity’s narrative arc bends toward cooperation and justice. Toward a future that appears sublime.

[Prum’s book is very recent, so major reviews are few, but a lengthy article on it has recently appeared in the New York Times, “Challenging Mainstream Thought About Beauty’s Big Hand in Evolution.” Meanwhile, Carol Dyhouse writes interestingly about the fear of female sexual power in her essay for Literary Hub, “Why are We So Afraid of Female Desire?”]

[You can follow Otterbein’s bro budgies on Facebook—they support climate science!]


  • Fascinating post, Richard. From the budgies to the peacocks and drakes. It must be such a relief to read a book that predicts a more sublime future based on evolution. In the midst of our craze for dystopia both in art and in life.

    I’m still stuck at an early paragraph, however. I collection of male budgies sings in relative harmony. A collection of females would fight. I would have guessed the opposite.

    • Richard says:

      Thanks, Shirley. In budgies, females are more aggressive. It may have to do with competition for nesting, food, and other chick-rearing resources.

  • I’ve kept a few budgies in my time–they do indeed have a lovely song. But that budgie on the left in the picture of the two yellow budgies doesn’t seem to have the blue crest on its nose–a possible male impersonator, sneaked into the house of song?

    • Richard says:

      Good eye, Victoria! The cere color in males isn’t blue in nontraditional patterns—such as pure yellows or mostly yellows created by human selective breeding. There, it’s kind of pink, at least in the males. Females have brown ceres and males blue, in wild type greens and wild-patterned blues.

      • Ah, in the proficiency of your answer, I sense a bird fancier–can it be that a budgie will someday enter your menagerie?

        • Richard says:

          I want an aviary of bro budgies REALLY bad! But, with my mania for husbandry and selective breeding, I’d be a damn budgie breeder in no time flat. My first pet was a parakeet named Hattie. As a teen, I studied budgie breeding in books, fascinated by the colors and huge sizes the Brits have bred.

  • J.V. Wylie says:

    Richard, Thank you for highlighting the importance of this book, which I am certain will become a classic. The fact that Darwin coupled “The Descent of Man” with “Selection in Relation to Sex” clearly indicates that he felt that sexual selection has been THE major influence in human evolution – more so than natural selection.

    In my judgment,Prum, although very significantly and authoritatively dismisses once and for all the “adaptionist” arguments against sexual selection, only scratches the surface as to how significant this mechanism has been in human evolution. In comparison to other animals, we are the species that “desires to be desired, i.e. we’re vain. Well over 80% of the motivation behind our behavior is generically the same as the peacock’s relationship to its tail (the other 20% being power — vanity+power=status).

    So in humans, sexual display is more of a driving force even than the evolved discernment of these displays in the “audience,” and the fact that we are all so driven to make creative, unusual, beautiful, stunning, eye-catching, brilliant, outrageous, ingenious, etc, etc. sexual displays (I call them “social displays”) is what sets our species apart form all others, the sheer scope and variety of them — the spiraling arms race of creativity; And this is the fruit of the pioneering females of our human tribe. And YES: display and choice is our destiny, not command and control.

  • Richard says:

    Great to hear from another expert on evolution here. Thanks, John. And love your “pioneering females of our human tribe” line. Maybe even better: “spiraling arms race of creativity.” How perfect.

    Display and choice—sign me up!

  • This is fascinating. I’ve requested the book from the library.

    • Richard says:

      I hope you like it, Valorie. In any case, please come back and let us know! I found it immensely clarifying and inspiring, obviously. So odd that it seems so revolutionary, when Darwin’s idea from which he extrapolates has been out there forever.

  • dclaud says:

    Richard: What an engaging and well-penned post, one of your best. What I like best is how chatty and informal the voice is amidst some really heavy and important material. This could — and should — have been published widely. We, your self-selected readers, are lucky. Finally, I know from personal experience how very difficult it is to write something like this that reads with such facility. Thanks.

    • dclaud: Thank you for articulating exactly what I was thinking.
      Richard: Bravo!

      I’m a little overwhelmed by life responsibilities at the moment, at the same time something deeply challenging is stirring in my mind and heart. Some day I may be able to tell you how profoundly this essay has mattered to me.

      I hope you’re enjoying a lovely summer!

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