The Reluctant Mr. Darwin

by David Quammen

  Wallace’s manuscript was titled “On the Tendency of Varieties to Depart Indefinitely from the Original Type.” It comprised about twenty pages of lucid, easy prose, written out in the author’s hand. Its cardinal point, signaled in the title, was that the difference between species (as a category) and variety (as a category) is merely a difference of degree. That is, the amount of variation seen between varieties within a species is not inherently limited; rather, those increments can accumulate boundlessly until a variety splits away, becoming a distinct species unto itself. The manuscript posited “a general principle in nature” causing many varieties to do exactly that. And they don’t just split from the parent species, Wallace asserted; they compete against it, sometimes outlive it, and eventually give rise to still other varieties differing more and more from the original type. Wallace, unlike Darwin, had coined no name for this “general principle.” But his manuscript built a case for it with logic very similar to Darwin’s own.

  “The life of wild animals,” Darwin read, “is a struggle for existence” in which “the weakest & least perfectly organized must always succumb.” That struggle is driven by the pressure of inherent population growth rates, yielding many more newborn individuals than can be supported by available food and habitat. Without mentioning Malthus by name, the manuscript gave a deft summary of Malthusian arithmetic. It noted that “variations from the typical form of a species” occur commonly among wild animals (as Wallace, the commercial collector, had often seen), and that most such variations “would affect, either favourably or adversely, the powers of prolonging existence.” For instance: “An antelope with shorter or weaker legs must necessarily suffer more from the attacks of the feline carnivora.” Lions would eat the slow ones. A passenger pigeon with less powerful wings would have trouble traveling widely to find food. Starvation and competition would eliminate the poor flyers. On the positive side, a giraffe with an especially long neck would have access to high leaves that the others couldn’t reach. During a famine it might sustain itself with that extra resource, while short-necked giraffes died away. Those creatures “best adapted” as a result of such small differences would eat better and defend themselves better, survive better and reproduce more abundantly, establishing sizable populations while less fortunate creatures lost the struggle and disappeared. The result would be “continued divergence” over long stretches of time, with “successive variations departing further and further from the original type.” Wallace’s manuscript ended with a flourish, suggesting that “all the phenomena presented by organized beings, their extinction & succession in past ages, & all the extraordinary modifications of form, instinct, and habits which they exhibit” are accountable to that nameless “general principle in nature.”

  A big claim. The cover letter was more modest. Here’s a hypothesis I’ve hit upon to explain the origin of species, Wallace said. He hoped it might seem as new to Mr. Darwin as it had to him when the notion first struck.

  It didn’t.

  27

  The manuscript was datelined: “Ternate, February 1858.” Wallace had mailed it from a tiny volcanic island in the northern Moluccas. As the story goes, he got his inspiration during an attack of malarial fever, while forced to lie bedridden suffering alternate cold and hot fits and unable to do anything but think. One thing he thought about, as he’d been doing for years, was how species come into existence. Having seen such a spectrum of variation in the wild, having charted the suspicious distribution of closely allied species, Wallace had become ever more persuaded of the reality of transmutation. But what was the causal mechanism? During his bout of fever, he happened to remember Malthus, whom he’d read more than a dozen years earlier. He recalled the geometric rates of population increase, the slower increases in available food, the consequent “checks” to human population growth. Suddenly it occurred to Wallace, just as it had to Darwin, that such checks also regulate animal populations in the wild. Pondering all that adversity and mortality, he asked himself why some individuals survive while so many others die. “And the answer,” as he recollected long afterward, was that “on the whole the best fitted live.” Accidental variation plus the imperatives of struggle result in differential survival; differential survival leads to adaptation; divergent adaptation over vast stretches of time leads to fleet antelopes, strong-winged pigeons, and tall giraffes. Bingo. “The more I thought over it the more I became convinced that I had at length found the long-sought-for law of nature that solved the problem of the origin of species.”

  When the fever broke, he got up and scribbled some notes. Within a few days he had written his manuscript and sent it to Darwin by the mail steamer that stopped at Ternate.

  Why had Wallace chosen Charles Darwin, of all people, to receive an outpouring of his febrile idea? It wasn’t because Wallace recognized Darwin as a fellow transmutationist. The older man, in his published writings and their few exchanged letters, had been too coy to give that much away. As far as Wallace knew, Mr. Darwin was merely a conscientious naturalist of the traditional sort, whose interests ran to biogeography, barnacles, and variation in poultry. But Wallace, thrilled with what he’d hit upon, eager to announce it, had to send the manuscript to somebody, and his options were limited. He’d already heard through Samuel Stevens of the derogatory mutters, in London, about his ventures into theory. The old boys at home thought he should stick to gathering salable beetles. He might well have ignored those dour signals and mailed his paper to Stevens anyway, for forwarding to the Annals, as he’d done with the earlier writings. But that didn’t seem wise, not this time; the stakes were too large, the concept too incendiary. Or maybe he was simply aiming higher. Who else did he know? Wallace was isolated out there in the islands, and not just by miles and water. His lack of scientific credentials, educational polish, and social position left him feeling marginal. He had grown discouraged by a sense that his “law” paper came and went quietly, attracting almost no notice. He had even complained about that in a letter to Darwin. Darwin had responded, as a kindly aside, that it wasn’t quite so—that Darwin’s friend Lyell, for one, had found the “law” paper intriguing.

  Lyell had? Sir Charles Lyell, Britain’s preeminent geologist? This was a delicious bit of flattery for Wallace’s modest ego. Now, half a year later, Wallace was hoping to play the Lyell connection. If the enclosed manuscript on species seems sufficiently important, he asked Darwin, would you please pass it along to Sir Charles?

  28

  Darwin felt crushed. He had only himself to blame. His dilatoriness, his perfectionism, his big mouth. Suddenly he was trapped, flattened, between the demands of honor and the claims of self-interest. He howled with pain. “Your words have come true with a vengeance,” he wrote Lyell, “that I shd. be forestalled.” Enclosed is a manuscript that Wallace asks me to send you, said Darwin. It’s well worth reading. It’s also, he added glumly, the closest thing to a précis of my own theory. (In the panic of the moment, he was overlooking a significant difference: Wallace focused on competition between varieties, not between individuals—that is, selection of one group versus another, not selection of individuals within a group.) “I never saw a more striking coincidence,” Darwin moaned. Even some of the phrases Wallace used, such as the “struggle for existence,” echoed what Darwin had already written into the draft of his big book. Wallace hadn’t asked him to help get the manuscript published, Darwin noted, only to share it with Lyell; but of course Darwin would write Wallace immediately and offer to send it to any journal. “So all my originality, whatever it may amount to,” he whined, “will be smashed.”

  Lyell, always a steady head, advised him to calm down. Maybe there was an alternative solution, less drastic than all-or-none priority. Joseph Hooker, also a sensible friend as well as a faithful one, was brought into the discussion. As days passed and letters flew back and forth, though, Darwin’s attention became split between the Wallace surprise and some family concerns not conducive to calm.

  A wave of
sickness hit the village and the household. His eldest surviving daughter, Etty, caught a sore throat that turned out to be diphtheria, a scary and relatively unknown disease in those days, which was running at epidemic levels across Britain. By the time Etty improved, there was another disease to fear: scarlet fever, which had broken out locally. Three children in the village died, others were hovering in danger, and on June 23 it hit baby Charles, the youngest Darwin.

  This namesake child is a mysterious figure, about whom evidence is scarce and scholars disagree. Born when Emma was forty-eight, christened Charles Waring Darwin, by the age of nineteen months he was a toddler who hadn’t toddled. Small for his age, he didn’t walk or talk. He had a sweet, tranquil disposition but seldom laughed, seldom cried, and made weird faces when he was excited. Evidently he had some sort of physical and mental debility, though it’s hard to say what. According to Etty’s later testimony, her littlest brother was born “without its full share of intelligence.” Of the two best and most thorough Darwin biographies, Janet Browne’s and the Desmond-and-Moore, the latter describes baby Charles as “severely retarded,” the former says that he “may have been slightly retarded,” possibly because of mercury poisoning from ill-conceived Victorian medicines. Randal Keynes, Darwin’s great-great-grandson, argues persuasively that Charles Waring suffered from Down Syndrome—that is, physical impairments resulting from an extra copy of the twenty-first chromosome. It was a perplexing condition at the time, not even partly clarified until Dr. John Langdon Down (no connection to Downe village or Down House) identified it eight years later. Whatever his trouble, baby Charles was loved by Darwin and Emma with a pitying tenderness that probably included some sense of burden and regret, making their feelings all the more complicated when he died of his fever on June 28.

  The end was ugly and hard, as it had been with Annie. Otherwise that death and this one were almost as different as two child-losses could be. “It was the most blessed relief,” Darwin told Hooker, “to see his poor little innocent face resume its sweet expression in the sleep of death.” Etty later described her parents’ reaction more bluntly, recalling that, “after their first sorrow, they could only feel thankful.” Darwin wrote a short, private memoir of Charles Waring, in which he did his best to accentuate the positive, recalling “nice little bubbling noises” the child sometimes made, how “elegant” he looked crawling naked on the floor, his “placid & joyful” disposition.

  In the meantime Darwin had heard back from Lyell with some thoughts about how the Wallace dilemma could be handled. What did Darwin have on paper, Lyell wondered, that might testify to his priority of discovery? Well, there was the manuscript essay of 1844, which Hooker had read; also a six-paragraph summary of the theory, which he’d sent last year to the botanist Asa Gray, his trusted correspondent at Harvard. These unpublished but witnessed writings were proof that he’d conceived the whole idea long ago, solitarily, and stolen nothing from Wallace. “I shd. be extremely glad now to publish a sketch of my general views in about a dozen pages or so,” he told Lyell. “But I cannot persuade myself that I can do so honourably.” He worried that receiving the Wallace manuscript—which he hadn’t asked for, after all—put him in a bind. He would rather burn his own book-in-progress, he said, than be seen as behaving shabbily. But was it too late to publish a summary of his views and say he was doing so on the advice (two years earlier) of Lyell? He repeated: “If I could honourably publish….” No, he couldn’t persuade himself that it was okay; but implicitly he begged Lyell and Hooker to do the persuading.

  Altogether, he was fuddled with anguish. He hated himself for thinking about such stuff while his children were battling for their lives. “This is a trumpery letter,” he ended, “influenced by trumpery feelings.” But the feelings wouldn’t go away.

  Lyell and Hooker took their cue. Within days, serving him faithfully as friends, serving science by their lights, serving justice more dubiously, they cooked up an arrangement that rescued the situation—or at least, it rescued Darwin’s interests. They certainly couldn’t ignore Wallace’s paper entirely and connive to see Darwin given credit alone; that would have been dishonorable, unprofessional, and scandalous when the truth came out. Instead they devised and sponsored a joint presentation of Wallace’s manuscript and Darwin’s unpublished work. This peculiar duet would occur at the next meeting of the Linnean Society, one of London’s better scientific associations, of which Hooker, Lyell, and Darwin were all governing members. Darwin consented to the arrangement, sending Hooker his 1844 essay and the six-paragraph summary he’d written for Gray, along with another disclaimer: “I daresay all is too late. I hardly care about it.” No wonder: The baby at that moment was still alive, but barely, fevering toward a crisis. Wallace, on the other hand, didn’t consent to the joint reading (at least, not in advance); he couldn’t, because no one consulted him. He was still doing fieldwork in the eastern islands, unreachable on short notice, far out of the loop. Nobody seems to have asked Lyell and Hooker: Gentlemen, what’s the all-fired hurry? Nobody suggested that Darwin, having waited twenty years to publish, might reasonably wait another six months for Wallace’s acquiescence. It was a done deal before anyone thought to quibble. The reason for hurry, I think, was that Lyell, Hooker, and Darwin all felt some embarrassment about this high-handed bestowal of shared credit, and they knew that delay might bring complications.

  So there was no delay. The insiders moved deftly and fast. The details were settled in a flurry of overnight letters between London and Downe. Hooker chose an excerpt from Darwin’s 1844 essay and inserted that, along with the Gray summary and Wallace’s manuscript, into an already full agenda for the Linnean Society meeting. These three statements were ordered alphabetically by author—Darwin’s two, followed by Wallace’s. On the evening of July 1, 1858, the Darwin-Wallace material and five other papers were read to an audience of about thirty people. Hooker and Lyell attended. By coincidence, so did Samuel Stevens, who may have wondered how this Wallace paper got to London without passing through his hands.

  The two authors were absent. By hindsight you might view them as “conspicuously absent,” although Wallace’s non-presence wasn’t notable at the time. He didn’t belong to the Linnean Society. His voice was admitted like the crawk of an exotic parrot, interesting and indelicate. He spent July 1 at a place called Dorey, a trading village on the northwestern coast of New Guinea, five hundred miles east of Ternate. The wet season had struck again, collectable birds were scarce around Dorey, but for insects the hunting was excellent. He’d been doing especially well with beetles. He was unaware of the event in London.

  Darwin, acutely aware, missed the Linnean meeting, too. He was home in Downe with a dead child and a bad case of ambivalence.

  29

  The most remarkable thing about Darwin-Wallace night at the Linnean Society is how little immediately came of it. No general discussion followed the reading of papers. No one stood up in response to what Darwin and Wallace proposed and said, That’s brilliant! or That’s outrageous! Tea was served, probably. There was some private chat. And then the Linnean fellows went home. The foundations of science had shifted beneath their feet but they didn’t notice.

  Why not? This is hard to know. Possibly it was because the excerpts from Darwin and the paper from Wallace focused on the circumstances and details of the mechanism, natural selection, not on its larger significance. The word “transmutation” wasn’t mentioned by either author, let alone the word “evolution” (though Darwin did allude to “the origin of species”). In the ears of a careless listener, on a hot July night, during an overlong meeting, the Darwin-Wallace readings with their roundabout logic may have seemed to involve merely varieties and variation. Another reason that the audience missed the point may have been that those Linnean fellows generally weren’t asking themselves the question—How do species change, one into another?—that Darwin and Wallace were answering.

  Two months later, the society’s Journal of Proceedings
published Darwin’s fragments and Wallace’s manuscript, lumping them as though they were a single co-authored paper. In the editing process, someone supplied a slightly garbled portmanteau title: “On the Tendency of Species to Form Varieties; and On the Perpetuation of Varieties & Species by Natural Means of Selection.” Printed, the three pieces carried more impact than they had in spoken delivery. At least a few scientists recognized that this was weighty stuff, for better or worse, though some only condescended to disparage it. The president of the Geological Society of Dublin declared to an audience, early the next year, that Darwin and Wallace’s paper “would not be worthy of notice” if Lyell and Hooker hadn’t acted as sponsors. “If it means what it says, it is a truism,” according to this man; “if it means anything more, it is contrary to fact.” Darwin heard about that criticism and savored it as “a taste of the future.” He was right.

  Other readers came across the Darwin-Wallace amalgam and were deeply affected. “I shall never forget the impression it made on me,” one naturalist, young at the time, wrote later. Hooker included references to “the ingenious and original reasonings” of Darwin and Wallace in his forthcoming work on Tasmanian plants, and Asa Gray described the Darwin-Wallace theory to an elite science club at Harvard, causing a disagreeable buzz in the head of Louis Agassiz, the eminent professor of natural history. So there was a scattering of strong reactions, but no explosion of acclaim or alarm. Either the central idea shared by Darwin and Wallace was too shocking for immediate absorption, or else other circumstances, somehow, hadn’t favored immediate uptake. Maybe the idea hadn’t been clearly enough expressed, or not cogently enough supported with factual evidence—or maybe people just weren’t paying attention. Anyway, it slipped past. When the president of the Linnean Society (who happened to be Darwin’s old reptile identifier from the post-Beagle days, Thomas Bell) gave his annual address the following May, he offered a bland retrospect of the past year. It hadn’t been enlivened, Bell said, by “any of those striking discoveries which at once revolutionize” a branch of science. Bell’s comment is now famous for its obtuseness. But in a strict sense he was right. The joint Darwin-Wallace announcement didn’t “at once” revolutionize biology. It was too elliptical and dry. Something more was necessary.