The Reluctant Mr. Darwin

by David Quammen

  He needed to ventilate his brain. In late June 1838, he broke away from London and its pressures—his editorial work on the Zoology, his chores for the Geological Society, possibly also the secret notebooks, unless he tucked “C” into a pocket—and went off to Scotland for a bit of geological fieldwork. He visited Glen Roy, a valley in the Highlands famous for the strange unexplained terraces traversing its slopes. Vacationing or not, he was a keen observer and a restless theorizer. After eight days in Glen Roy, he had his own notion about the origin of the shelves, and once back in London, amid all the other work, he’d make time to write a Glen Roy paper. But on the way south he stopped again in Shrewsbury for a family visit.

  Talking with his father, Darwin got some brusque, cheerful advice: Quit worrying about money, you’ll have plenty, and get married before you’re too old to enjoy the kids. Dr. Darwin himself had been forty-three when Charles was born. The good news about financial support helped to rearrange Darwin’s thinking. He drew up another orderly page of marital pros and cons, and this time “Marry” headed the longer column on the left, “Not Marry” the shorter one on the right. Marriage would give him a constant companion and a friend in old age, who would be “better than a dog anyhow.” It was intolerable to think of spending one’s whole life on nothing but work. “Only picture to yourself a nice soft wife on a sofa with good fire, & books & music perhaps.” The Horner girls didn’t fit that picture. Turning the sheet over, he wrote: “It being proved necessary to Marry…When? Soon or Late.” The other question he might have added was: Whom?

  Before heading back to London he visited his cousins, the Wedgwoods (of the famous pottery business and the family fortune it had built), at their mansion in the next shire. It was the safest household he knew outside his own family home. Considering the gruffness of his father and the supportive amiability of his uncle, Josiah Wedgwood, maybe it was the safest household, period. And, oh, there were unmarried Wedgwood girls.

  5

  By then he had begun notebook “D,” the third in his transmutation series. “Mine is a bold theory,” Darwin wrote, meaning the big one about species, not the little one he’d just concocted about Glen Roy, “which attempts to explain, or asserts to be explicable every instinct in animals.” Yes, it asserted that animal instincts and much more were “explicable,” but it did not explain those phenomena; it merely noted the fact that species are interconnected by common ancestry. Darwin still hadn’t proposed a mechanism for how transmutation occurs. Noodling on, he recorded some facts about Muscovy ducks, white-headed Sussex cattle, glowworms, and again the apteryx. From the anatomist Richard Owen he gleaned that reptilian skeletal structure is very similar to avian skeletal structure, as evident in a young ostrich. But Owen wasn’t inclined to make as much of the reptile-bird similarity as he did. “There must be some law,” Darwin told the notebook, “that whatever organization an animal has, it tends to multiply & IMPROVE on it.” But what was the law? He still didn’t know.

  Despite the time lost to his unexplained illness early in the summer, by autumn he was back in a groove. He finished the Glen Roy paper. He worked on another geology manuscript, related to those endlessly ongoing Beagle publications. He pondered transmutation and also, by testimony to another little diary, he “thought much upon religion.” The entry is cryptic, but it’s safe to assume he wasn’t experiencing an accession of piety. Probably he was worrying over the conflict between religious dogma as filtered through natural theology and, on the other hand, the view of origins he now held. He cast about for facts, alternative perspectives, and authority, reading the journal of an expedition to eastern Australia, Edward Gibbon’s autobiography, John Ray’s The Wisdom of God, and three volumes of a biography of Walter Scott. He read books about birds, Mt. Aetna, physiognomy, epistemology, and Paraguay. And then, in September of that year, 1838, he picked up the sixth edition of Thomas Malthus’s Essay on the Principle of Population.

  He would have known something of Malthus already, by cultural osmosis, in the same way an educated person today is at least vaguely aware of Milton Friedman or Jean-Paul Sartre. His brother’s favorite dinner partner, Harriet Martineau, was an ardent popularizer of Malthus’s views. The Essay on Population, first published anonymously in 1798 and expanded in later editions, offered a political economist’s dispassionate analysis that undergirded the Whig program of hard-nosed welfare reform. Easy charity was bad and pointless, according to Malthus. It only encouraged population increase among poor people, without generating any commensurate increase in the national supply of food. That caused prices to rise for everybody. Eliminate unquestioning relief, force the poor to compete as laborers or be locked into workhouses, educate them against the disadvantages of profligate reproduction, and the problem of mass poverty would be ameliorated, if not solved. This was Malthusian social logic. It entailed stern thinking and, with a little exaggeration or distortion, could seem even sterner. Darwin was a mild, generous soul and he may have found it, as described secondhand, too callous.

  What he probably didn’t know until he had Malthus’s book in his hands was that it mentioned animal and plant populations as well as human ones. On the first page Malthus paraphrased Benjamin Franklin, of all people, to the effect that every species has a tendency to proliferate beyond its available resources, and that nothing limits the total number of individuals except “their crowding and interfering with each other’s means of subsistence.” Empty the planet of life, Franklin had posited, seed it anew with just one or two forms—fennel plants, say, or Englishmen—and within a relatively short time Earth will be overrun with nothing but Englishmen and fennel. The inherent rate of population growth is geometric—that is, any population can multiply itself by some factor, not just add to itself, with each generation. For humans, Malthus calculated, the inherent rate amounts to doubling a population every twenty-five years. For fennel, which sets hundreds of tiny fruits on each plant, the inherent rate of population growth is much higher. But the inherent rate is just a biological possibility; such extreme increases seldom happen. Under normal circumstances, on a teeming planet as opposed to an empty one, runaway population growth is prevented by what Malthus called “checks.”

  The ultimate check is starvation. For humans it results from the fact that, while population is increasing geometrically, ever-intensified efforts at land clearance and agricultural improvement only increase the food supply arithmetically. That is, the sequence 2, 4, 8, 16, 32, 64, 128 runs away from the sequence 2, 3, 4, 5, 6, 7, 8. But food supply directly limits population numbers only during famine. Another kind of check is voluntary: the decision to refrain from marrying, to marry late in life, or to practice birth control (of which Malthus, a wholesome parson of pre-Victorian views, didn’t approve). Still other checks operate continually: overcrowding, unwholesome work, extreme poverty, bad care of children, endemic disease, epidemic, war, and anything else that might contribute to sterility, sexual abstinence, or early death. Generally speaking, Malthus wrote, you could boil them all down into “moral restraint, vice, and misery.” Darwin read this and something went click. He was less interested in moral restraint and vice than in what “misery” might mean to a mockingbird, a tortoise, an ape, or a stalk of fennel.

  He ruminated in his “D” notebook about “the warring of the species as inference from Malthus.” The geometric population increase of animals, as of humans, is prevented by such Malthusian checks, he wrote. He imagined it all freshly. Take the birds of Europe. They are well known to naturalists and their populations are (or were in his time, anyway) relatively stable. Every year, each species suffers a steady rate of death from hawk predation, from cold, from other causes, roughly maintaining its net population level against the rate of increase from fledglings. Food supply remains limited, nesting space remains limited, but breeding, laying, and hatching continue to push against those limits. Everything is interconnected and uneasily balanced. If the hawks decrease in number, the bird populations they prey upon will be
affected, somehow. With new clarity Darwin saw predation, competition, excess reproduction, death—and their consequences. “One may say there is a force like a hundred thousand wedges,” he wrote, and that it’s trying to “force every kind of adapted structure into the gaps in the oeconomy of Nature, or rather forming gaps by thrusting out weaker ones.” The final result of all this wedging, Darwin added, “must be to sort out proper structure & adapt it to change.”

  In shorthand scrawl, he had his big idea. Years later he would articulate the details and call it “natural selection.”

  6

  The wedges metaphor went into his notebook on September 28. And then an odd thing occurred, by way of visible aftermath to this momentous epiphany: nothing. Darwin held his cards close and kept a poker face to the world.

  In private he continued the notebook ruminations, finishing “D” with a burst of comments on the “differences” (that is, variations) among offspring in consequence of sexual reproduction, and starting the next in his transmutation series, notebook “E,” with some increasingly confident references to “my theory.” His theory explained how those small differences can accumulate into adaptations particular to differing circumstances. His theory, he realized, would be quite a horse pill for other people to swallow. Trying to keep his thoughts compartmented, Darwin also began another notebook, labeled “N,” which was devoted to “metaphysical enquiries” provoked by the scientific ideas he was considering. Does a dog have a conscience? Does a bee have a sense of communal responsibility? Is the human conscience just another form of inherited instinct, an adaptation for social behavior? Is the human mind just a function of the human body? Does the idea of God arise naturally in human minds from that instinctive conscience? Months earlier he had posed almost the same question about God and conscience—whether “love of the deity” might result simply from brain structure—and then had scolded himself delightedly: “oh you Materialist!” Now his materialism was getting deeper, firmer, less embarrassed. Still, he didn’t feel ready to go public. There were already enough materialistic evolutionary radicals, he knew, amid the current political squabbling about Chartism, democratized medical education, changes to the Poor Law, and they weren’t his kind of people.

  It was the dizziest season of Darwin’s life. He stopped writing letters to his friends and family. He kept busy at his Beagle-related tasks, guiding a volume of the Zoology into print and adding a preface to his own expedition Journal. He performed his duties as secretary of the Geological Society. His health was going bad, in some still unexplained way, and he needed rest. He trusted his most serious thoughts only to the notebooks. “Having proved mens & brutes bodies on one type,” he wrote, it would be “almost superfluous to consider minds,” adding, “yet I will not shirk difficulty.” In early November, two themes dominated his notations: the importance of sex and the search for laws. Sexual reproduction (as distinct from vegetative reproduction or budding, whereby an individual microbe or plant reproduces itself exactly) entails the paradox of inherited variation—that is, slight differences between parents and offspring, as a result of the mixing of elements from two parents. Fundamental laws (as distinct from divine whim) govern the occurrence of variation and the transmutation of species. He wanted to illuminate those “laws of life.” In the midst of this heightened sense of danger, excitement, and solitude, he did something uncharacteristically impulsive: He hopped on a train for Staffordshire, turned up at the home of his uncle Josiah Wedgwood, and asked his cousin Emma to marry him. It was a reckless leap toward safety.

  His proposal surprised her. Emma was a sweet-spirited and pious thirty-year-old, on the brink of what in those days was considered spinsterhood. She and a hunchbacked elder sister were the last Wedgwood girls left in the house. She had known Charles nearly all her life, as the boy-cousin closest to her in age (though she was slightly older), and the families were cross-linked by multiple marriage connections. Charles’s mother, who died when he was eight, had been the sister of Uncle Josiah, and just a year before this sudden offer to Emma, Charles’s sister Caroline had married the eldest Wedgwood son, another Josiah. Even Charles’s Wedgwood grandmother, his mother’s mother, had been a Wedgwood by birth who married her cousin, another Wedgwood. First-cousin marriage was common in those days and those circles, though that’s not to say people weren’t aware that too much inbreeding could bring problems; otherwise they’d have been marrying their sisters and brothers. On the positive side, unions between cousins helped keep family fortunes together. So the pairing of Charles and Emma was an obvious one, in some ways. Would-be matchmakers in the Wedgwood family had probably pondered it more consciously than the principals ever had. Still, as these two cousins aged, it hadn’t looked likely to happen. Charles had paid Emma some attention during his visit in July, though not with enough ardor to suggest that those few conversations were supposed to constitute courting. Now here he was out of nowhere—having done his private calculus of upsides and downsides and concluded he should marry someone—putting himself forward, humbly but abruptly, as her suitor.

  The surprise went two ways. When she accepted him on the spot, he was startled. Then they both let the idea sink in. There was no whoop-de-doo echoing through the house that day. Emma felt “bewildered” rather than giddy, and Charles had a headache. Everyone else, both fathers included, clucked their conventional noises of approval. Charley and Emma, of course, how perfect.

  It wasn’t perfect. One imperfection was the discrepancy between Emma’s fervent, Bible-based Christianity and Charles’s recent free fall into disbelief. Charles himself didn’t yet know how far that fall would drop him or where he would land. But his father had warned him, probably just months earlier, that a man with theological doubts should conceal them from his wife. Nothing to be gained for anyone, according to the hardheaded doctor, in giving a woman cause to worry about the salvation of her husband’s soul. Things might go along well until one of them got sick, and then she would suffer miserably at the thought of eternal separation, making him miserable, too. Charles promptly ignored his father’s advice (which may have been the most prescient thing, if not the wisest, that Dr. Darwin ever said to him), telling Emma at least something of his heterodox thinking. Most likely he didn’t raise the topics of transmutation, monkey ancestors, the idea of the deity as an inherited instinct, or the conundrum of male nipples, but whatever degree of apostasy he confessed was enough that she called it “a painful void between us.” Then she brightened up and thanked him for his candor, having reassured herself that “honest & conscientious doubts cannot be a sin.”

  Doubts? That was putting it politely. By this time he had a whole new framework of scientific and metaphysical convictions, not just doubts. But if she was willing to twine their fingers together across the void and ignore it, so was he. Nowhere on his clerkish lists of marital benefits had he posited that a wife should be a philosophical soul mate and a full intellectual peer. He told his friend Lyell, in a letter announcing the engagement, of his “most sincere love & hearty gratitude” toward Emma—gratitude for “accepting such a one” as him. This was probably a candid statement, more revealing than he wished: his love tepid but genuine, his gratefulness robust.

  Back in London, he returned briefly to the “E” notebook before house-hunting and other domestic preparations swamped him. Near the end of November, with his usual bumpy punctuation, he wrote:

  Three principles, will account for all

  Grandchildren. like. grandfathers

  Tendency to small change…especially with physical change

  Great fertility in proportion to support of parents

  Bare and elliptical, it was his first full outline of the three causal conditions for natural selection: (1) hereditary continuity across multiple generations; (2) incremental variations among offspring; and (3) the Malthusian factor of inherent population growth rate, producing so many unsupportable individuals. Put them together and you had an explanation of how species transmuta
tion occurs.

  So much for the notebook. In his personal diary, he wrote: “Wasted entirely the last week of November.” Was he complaining, apologizing, or bragging jocularly about a newfound sense of lightness? In early December, Emma came to town and stayed two weeks with her brother and sister-in-law, during which she and Charles threw themselves into the merry fuss of setting up a household. Then she went back to Staffordshire. To the end of the year, he occupied himself with further house-hunting, a bit of reading, and being laid up intermittently by his mystery illness. Having decided the marriage question, he was now impatient for the wedding to occur. His letters to Emma were cheery. In one, at the end of a long day, he described himself complacently as “stupid & comfortable.”

  On January 29, 1839, they were married in a small church near the Wedgwood mansion. Charles’s brother didn’t come up from London for the event, and Emma’s mother stayed home sick. Dr. Darwin and Uncle Josiah had arranged bounteous financial settlements, formalized in a document at the county records office: £10,000 from Dr. Darwin’s deep pocket, £5,000 from the Wedgwood side, to be invested on behalf of the newlyweds at 4 percent annually. That meant Charles wouldn’t need a job and they’d have servants in the house. They were young gentlefolk from affluent, provident families. The marriage ceremony was performed by Reverend Allen Wedgwood, a cousin to everybody. There was no reception, but not because the Wedgwoods couldn’t afford a party. There was no honeymoon, but not because the couple didn’t want to be alone.