Objectifying Male Birds

By 1858 London had grown to be the largest city on earth, yet its nearly two and a half million inhabitants had no effective sewage system. Prior to the 1840s the city’s 200,000 cesspools had provided some degree of sanitation, but they often overflowed, and they needed to be emptied by hand so that their contents could be transported out of the city and sold as fertilizer. It was doubtless a messy process, but the solution implemented by the great sanitary crusader Edwin Chadwick in 1842 was, in the end, even worse. He had the city’s human effluent diverted into the sewers, which had been built to carry rainwater into the Thames. As a result, so great a volume of waste flowed into the river that the water drunk by Londoners was mixed with raw sewage.

The full extent of Chadwick’s folly became evident in the summer of 1858, when unprecedented heat cooked the river into a putrescent stew that stunk so vilely it interrupted all nearby human activity. On June 16 the temperature in London broke all records, reaching 94.5 degrees Fahrenheit in the shade, and prompting a lawyer working at the Riverside Temple Bar to write, “The stench of the Temple to-day is sickening and nauseous in the extreme…. I am being killed by inches.” Things were no better in Parliament, with many members decamping to the countryside, and even the stalwarts being forced on occasion to rush from the chambers, holding handkerchiefs over their noses.

Through it all the fifty-three-year-old Benjamin Disraeli, chancellor of the Exchequer in Lord Derby’s reforming Tory government, toiled on, seeking passage of his Thames Purification Bill. That summer, he was also responsible for the passage of several other bills, including one allowing Jews elected to Parliament to take their oath of office by swearing on the Old Testament (rather than the Christian Bible) and others that reformed the practice of medicine, simplified divorce, and made India a British colony.

Born a Jew, Disraeli had been baptized into the Church of England as a teenager. (His father had been advised to take the step to spare his son discrimination.) His wife, Mary Anne, who was thirteen years older than her husband, was a merry dresser who in 1871, at the age of seventy-eight, appeared in “youthful muslins, profusely decorated with blue and yellow ribbons.” Disraeli was devoted to her and exceeded her in dandification. His luxuriant curly locks and extravagant clothing, which included purple trousers, scarlet waistcoats, and white gloves with gold rings worn on the outside, were much commented upon. The prime minister regarded his chancellor as flamboyant and untrustworthy, which Disraeli may have been. But he was also talented and hard-working.

For all Disraeli’s political skills, the Great Stink of 1858 must be given some credit for the passage of so many reform bills during that summer. As an epic poem published in Punch put it:

Who…thinned full many an
     awkward House!
   Who sped along the
     India Bill?
Who huddled up the Jewish
     claims?
   …who but Father Thames?

Rosemary Ashton, the author of One Hot Summer, describes her book about the Great Stink as a “microhistory.” The discipline, she explains, has been mightily aided by the digitization of The Times and other nineteenth-century newspapers: the unprecedented access to them allows the historian not only to study the lives of great men like Disraeli, Charles Darwin, and Charles Dickens, but to see unexpected patterns and hidden connections. It must be said, however, that the relationships of Ashton’s three main figures to one another, and of each to the Great Stink, are often so distant as to threaten her narrative.

Yet 1858 was crucial to all three. Disraeli saw much success as chancellor, while Dickens, courtesy of an extramarital affair, saw his career stall and almost run off the rails. Perceived through his writings as a sentimental and wholesome family man, he had ten children with his wife, Catherine. But now he found himself falling in love with the much younger actress Ellen Ternan. Terrified that rumors of the liaison would spread and worried about the impact of adverse publicity on his new business venture, which involved public readings of his works, he published a statement in The Times in which he airily referred to “abominably false” rumors. Hardly surprisingly, those who had heard nothing of his indiscretion began to wonder what the rumors were, and the gutter press set about satisfying their curiosity. Dickens’s reputation survived, but 1858 became known as the year without a Dickens novel.

As for Ashton’s third giant, 1858 was for Charles Darwin a bittersweet year in the extreme, and nowhere is Ashton’s claim that her style of history allows her to see hidden connections demonstrated more ably than in her account of the relationship between the two cofounders of the theory of evolution by natural selection: Darwin and Alfred Russel Wallace. By mid-June 1858 Darwin had been working on his evolutionary theory for over twenty years. Most of that time he had been torn between a desire to publish and so claim the idea as his own, and a fear of how his Godless thesis might affect his wife Emma and other deeply religious people.

The matter was forced that summer when, at a comfortable distance from the Thames in his home in Kent, Darwin opened a letter from Wallace and got what Ashton calls “the fright of his life.” As he wrote to his friend Charles Lyell, “I never saw a more striking co-incidence. If Wallace had my M.S. sketch written out in 1842 he could not have made a better short abstract!… So all my originality, whatever it may amount to, will be smashed.”

Wallace had not asked Darwin for help in getting his own paper on evolution published. Yet Darwin felt obliged to do the right thing. Deeply troubled by his desire to claim priority, he sent a second letter to Lyell, suggesting that he would be willing to see a “sketch” of his own theory, written in 1844, published. By the end of June Lyell proposed that Wallace’s paper and Darwin’s sketch, along with some of his other writings, be read at the forthcoming meeting of the Linnaean Society in London, scheduled for the evening of July 1.

The timing of the event would bring the tension between Darwin’s ambition and his family life to the breaking point. Darwin’s youngest child, Charles Waring Darwin, who was just eighteen months old, had died, and his burial service was scheduled for the very day that Darwin’s paper describing evolution by natural selection was to be read before the Linnaean Society. It is difficult to imagine his state of mind on July 1, 1858. His wife Emma needed her faith more than ever, yet Darwin knew that on that day his theory usurping God’s position as creator would be unleashed on the world.

When On the Origin of Species was published a little over a year later, Emma became gravely distressed at the criticism it attracted, especially that coming from the clergy. She was particularly upset by the response of the geologist Adam Sedgwick, who thought parts of the book “utterly false & grievously mischievous.” Despite being rivals, both Darwin and Wallace acted impeccably in relation to each other. Following the publication of his paper on evolution in 1858, Wallace wrote to the botanist Joseph Hooker:

It would have caused me much pain & regret had Mr Darwin’s excess of generosity led him to make public my paper unaccompanied by his own much earlier & I doubt not much more complete views on the same subject, & I must again thank you for the course you have adopted, which while strictly just to both parties, is so favourable to myself.

For his part, Darwin expressed his obligation to Wallace for being the impetus for his writing the Origin rather than a multivolume work that “very few would have had the patience to read.” After 1858, the careers of Darwin and Wallace diverged, with Darwin devoting his life to investigating what Wallace would come to call “Darwinism,” while Wallace went on to become a great anti-pollution campaigner and author of Man’s Place in the Universe (1904), which arguably founded astrobiology, the study of the origin, evolution, and distribution of life in the universe. Their cordiality never diminished, with Wallace serving as a pallbearer at Darwin’s funeral in 1882.

Richard Prum’s The Evolution of Beauty takes up the story of how evolutionary thought developed after the publication of Darwin’s Origin. Its point of departure is Darwin’s The Descent of Man, and Selection in Relation to Sex (1871). In it Darwin proposes what Prum calls a

second, independent mechanism of evolution—sexual selection—to account for armaments and ornaments, battle and beauty. If the results of natural selection were determined by the differential survival of heritable variations, then the results of sexual selection were determined by their differential sexual success—that is, by those heritable features that contribute to success at obtaining mates.

For Darwin, sexual selection was responsible for the evolution of qualities ranging from the singing and colorful plumage of birds to human social life, language, and music. As Prum admits, the theory “that mate choice had resulted in the evolution of many of those traits in nature that are so pleasing and beautiful” has been strongly resisted, from Wallace on, by most evolutionary biologists, who see sexual selection as no more than one component of natural selection.

This may seem like a small matter, but to Prum it is of the utmost importance, for he sees natural selection as resulting in the improved functioning of organisms, while sexual selection, which cares primarily for beauty, can have the opposite result. From the earliest times, humans have mused on the origins and meanings of beauty. Plato famously associated the beautiful with the good. But in the Symposium, the great philosopher quotes his female teacher Diotima as saying that beauty is “the object of every love’s yearning.” As you might guess from Prum’s title, Diotima’s insight accords precisely with his thinking on the subject.

Prum is a professor of ornithology at Yale and has spent most of his research career studying bird behavior in South America. His great specialty is a group of wren-sized birds known as manakins, which inhabit the American tropics and whose name is derived from the Dutch for “little man.” These elfin creatures exhibit some of the most unusual and entertaining behaviors in the animal kingdom, which results, Prum says, from their peculiar social structure. The females are drab, solitary creatures, except when raising young or for the brief moment when they mate. The males, however, are gaudy and spend their entire lives in tight associations with other males. They contribute nothing to raising their young. Instead, all of their efforts go into performances.

The blue manakin may be the clearest example in the natural world of Diotima’s dictum that beauty is merely “the object of every love’s yearning.” Males are brilliant blue and black with scarlet heads, and groups of up to five of them perform a “cartwheel” dance that involves the males perching on a branch and leapfrogging backward over one another while fluffing their red crowns. If impressed, the female for whom the dance is performed will mate with the dominant member of the troupe. In such a system few males ever get to mate, and it is this extreme selection by female manakins, in which only the most beautiful and accomplished males get to pass on their genes to the next generation, that has led to their elaborate displays and colors.

Prum characterizes blue manakin society as “a giant Ponzi scheme in which over 90 percent of males must lose.” As an evolutionary biologist, he asks why the males persist with it. His answer is that they have no choice: because males have no penises, “active female participation is virtually required for the intake of sperm [from the male cloaca] into the female cloaca.” Males cannot impose themselves on females and so must compete to be the chosen mate.

The question of bird penises, or the lack thereof, is a great conundrum. Although the ancestors of the birds possessed penises, over 95 percent of living bird species lack one, and Prum thinks he knows why: the “penis was lost because females explicitly preferred males without penises…. Through the loss of the penis, female…birds have essentially won the battle of sexual conflict over fertilization.” Just how this might have occurred is not explained, but almost by way of a moral fable, Prum gives a detailed account of the sex life of one group of birds that retain their penises—the ducks.

Some male ducks have not just retained their penises, but have developed the most extravagant todgers on the planet. These extraordinary organs, which can inflate at the rate of three and a half miles per hour, are coiled and armed with hard ribs. They result, Prum argues, not from female choice but from an arms race between the sexes. This occurs because male ducks can force mating on females. Indeed, groups of males will cooperate to harass females until they acquiesce to sex, and sometimes the harassment ends in the death of the female, resulting in a skewed male-to-female ratio that only increases the competition among males. Female ducks have responded by evolving intricate vaginas than can baffle an ordinary penis—hence the truly extraordinary ones of some male ducks. The champion in this regard is the Argentine lake duck, which has an “explosive” penis that is longer than its body.

The chapters of The Evolution of Beauty dealing with avian sexual selection are full of extraordinary insights. Some of the most interesting material, however, is hidden away in footnotes, including the proclivity of some female birds to keep harems of males and the theory, which Prum challenges, that genetic benefits may accrue from female ducks being inseminated by rapist males, so that they then have successful rapist sons.

In the last part of his book Prum takes the lessons he has learned from studying birds and applies them to humans, asserting that many aspects of human biology and behavior only exist because women like them, while other features exist because they appeal to men. This has important implications, for if one sex is to drive evolution in the other, it must be picky about its mates. Therefore most male humans must definitely not be like Don Giovanni in Mozart’s opera, of whom it is said:

It doesn’t matter if she’s rich,
Ugly or beautiful;
If she wears a petticoat,
You know what he does.

According to Prum, one of the features that women have looked favorably upon as they choose the fathers of their children is a thick, long penis with a shapely head. As he puts it, “The human penis is a complex sexual ornament whose various features evolved to be experienced through two distinct sensory modalities: vision and touch.” Other evolutionary biologists, it must be said, demur, insisting that these traits result from natural selection for better functioning.

Perhaps more remarkable is Prum’s suggestion that thicker, longer, more dangling scrotums result from selection by women, who find them aesthetically pleasing. When I mentioned this to my wife she merely cocked an eyebrow. I know that broader research may well reveal a different answer, but I found her skeptical expression telling.

Wherever he looks, Prum finds evidence for sexual selection by women, even seeing it as the cause of homosexuality among humans. “The evolutionary queering of the human species likely proceeded through female sexual desire to escape coercive male control,” he opines. The mechanism he suggests is that as females selected for more social males, they incidentally selected for a propensity toward homosexual behavior. Toward the end of his book, Prum devotes a chapter to art, arguing that the relationship between artists and those who appreciate their works operates like sexual selection, an observation that he believes “opens up an entirely new connection between evolutionary biology and the arts.”

The experience of seeing evidence of your favorite theory everywhere is prevalent among scientists. Randolph Kirkpatrick was a respected assistant keeper of lower invertebrates at the British Natural History Museum who in 1915 published a splendid two-volume monograph, The Nummulosphere, arguing that the entire planet was composed of the remains of single-celled marine organisms known as nummulites. He was apparently genuine in his belief, even going as far as publishing photographs of supposed nummulites in granite and basalt (rocks in which no fossils have ever been found). The poor fellow had evidently been looking down a microscope at nummulites for far too long, and so began seeing their distinctive shape everywhere. Kirkpatrick’s case is doubtless the most extreme example of what we might call “nummulitis”—a condition that often afflicts scientists and for which, I fear, some evidence may be discerned in Prum’s book.

Most humans form pair bonds, which means that there is a problem with female choice as a driver of evolution in our species. For female choice to drive evolution in humans as it does in manakins, a few males must father many children, which would involve widespread female deceit. Yet genetic evidence for such deceit is lacking. That said, Prum does a great service in showing how limited research into human sexuality is. As he argues, asking young men to look at images of women of various shapes and to rank them for their attractiveness provides very little information about the kinds of women the men will eventually partner and have children with.

The reason that Prum thinks that sexual selection is so important is that it results in features that are purely aesthetic, and that have no function beyond pleasing the choosier sex (which in birds are mostly females), and that can even result in a loss of “fitness” in the males. This is indisputably true. But is this form of selection really so different from other kinds of natural selection? The malarial parasite, for example, can result in selection among humans for sickle-cell anemia, which offers some protection against malaria; but a propensity to develop sickle-cell anemia can reduce “fitness” in descendants living where malaria does not exist. Moreover, beauty can be found in features that result from natural rather than sexual selection, such as the striped rear of the okapi or the elegant neck of the giraffe.

Despite these quibbles, The Evolution of Beauty has much to recommend it, both as a provocation to the complacency of much contemporary evolutionary thinking and as a scientific hypothesis to be tested.