The Reluctant Mr. Darwin

by David Quammen

  Although The Origin is the founding text of evolutionary biology, you can get a Ph.D. in that field at many American universities, and probably at British ones too, without having read it. Such neglect of a seminal document is oddly shortsighted, given that evolutionary biology itself is a historical science, concerned with examining and understanding the past as well as the present. The study of evolution proceeds from observed facts and found data more than from controlled experimentation. It still relies on Darwin’s ideas and Darwin’s terminology—most notably, on the idea and term “natural selection”—but its professional courses of training generally don’t require students to read Darwin. That’s too bad, because reading Darwin can be fun, even thrilling, as well as instructive.

  It isn’t always. In the course of his working life as a naturalist (an “amateur” naturalist, in the sense that he never held a job of any sort, let alone a scientific appointment) and a freelance writer (who liked making money from his books, though he didn’t need to), Darwin wrote his share of somniferous duds. The harder and longer he labored, it seems, the more likely he was to produce a big, boring tome, chockful of carefully gathered facts, judiciously framed questions, and arcane conclusions, all presented with relentless lack of economy or flow. The Variation of Animals and Plants under Domestication, published in 1868, is no page-turner. Nor can I much recommend The Different Forms of Flowers on Plants of the Same Species, which came out in 1877. Some of his shorter books (they’re not very short), such as Insectivorous Plants and The Various Contrivances by Which Orchids Are Fertilised by Insects, contain nice samples of one of Darwin’s most appealing literary modes—his close, gentle examination of quirky creatures embodying large biological themes. But are those books urgent and compelling? Are they lively, readable works overall? No. His very last book, The Formation of Vegetable Mould, through the Action of Worms, with Observations on Their Habits, is a pleasant little surprise, largely because it’s so unpretentious and eccentric. His barnacle volumes can’t be counted against him, since those were always intended for the reference of specialists. The Journal of Researches (or, under its modern title, The Voyage of the Beagle) is the most accessible of his books, a colorful outpouring of narrative and description in the voice of a curious, unassuming young man; but it doesn’t carry his strengths as a mature, conceptualizing scientist. His autobiography was written as a private memoir, for the family, and never published during his lifetime. The Descent of Man is really two books smooshed into one, as its full title admits: The Descent of Man, and Selection in Relation to Sex. The smooshing is far from seamless; there’s a big, lumpy transition after the first seven chapters, right where Descent gives way to Sex. Humanity’s descent from an animal lineage was one of Darwin’s boldest ideas, true, but that book on the subject isn’t one of his best efforts. Published in 1871, intended as a complement to The Origin of Species, it doesn’t have the same sharp focus, inexorable momentum, and magisterial power. It sold well at the time, thanks to the notoriety of his ideas, but it doesn’t reward attention nowadays as much as The Origin does.

  Haste and anxiety seem to have been good for Darwin, at least as a writer, at least in the one crucial case. Alfred Wallace, by shocking him with the threat of preemption, forcing his hand, inadvertently did him a big favor. The quick-and-dirty “abstract” proved to be readable, popular, persuasive, and efficacious in a way that the big book on natural selection wouldn’t have been. That big book remained unfinished by Darwin, and unpublished during his lifetime, partly because he had lost interest in its grand schema of encyclopedic exposition and partly because The Origin had rendered it unnecessary. He did salvage the first two chapters, converting them into his book on domestic variation. The rest of the long manuscript, comprising eight and a half chapters, didn’t see daylight until 1973, when a scholar named R. C. Stauffer edited it for publication under the title Charles Darwin’s Natural Selection. Although Stauffer’s edition is useful as textual background, its main value lies in making The Origin look good by contrast. It shows how lucky Darwin was—and readers too—that Alfred Wallace barged in when he did.

  The littler book, Darwin’s abominated volume, has a more complicated editorial history. Let’s say you’ve decided to read or to reread The Origin of Species. Immediately you face another decision: Which Origin? Six different editions appeared in England during his lifetime, each of the latter five showing revisions by the author. Many of those revisions were substantive. Sentences were added and others cut, passages were rewritten for clarity, second thoughts replaced first thoughts and then third thoughts replaced those, qualifications were inserted, fudges were factored, whole blocks of new argument answered criticisms of the more astute reviewers. Another literary scholar, Morse Peckham, assembled all the changes made throughout sequential editions into a “variorum text” of The Origin, published in 1959 on the book’s centenary. From Peckham we know, for instance, that for the hurried second edition demanded by John Murray after the sellout, 9 sentences were dropped, 30 were added, and 483 received some tinkering. To the third edition, in 1861, Darwin attached what he called “An Historical Sketch of the Recent Progress of Opinion on the Origin of Species”—that is, a survey of his intellectual predecessors—in response to accusations that he was taking credit for ideas that others had published before him. This sketch, placed as a preface, acknowledged earlier thinking by Lamarck, Geoffroy, his old Edinburgh mentor Robert Grant, the still anonymous author of Vestiges, the anatomist Richard Owen, an obscure writer on shipbuilding timber named Patrick Matthew (who’d gotten jealously miffed over Darwin’s natural selection, insisting he’d mentioned the same idea back in 1831), and his own grandfather Erasmus, among others.

  For the fourth edition, in 1866, Darwin added two pages of further credits to the historical sketch and expanded the main text by 10 percent, including an enlarged section on embryology and development. The fifth edition was the first in which Darwin adopted Herbert Spencer’s famous phrase, “the Survival of the Fittest,” as a rough synonym for natural selection. All these later editions incorporated more supporting facts and examples, some drawn from the recent work of scientists inspired by The Origin itself as the cycle of evolutionary theory and research began to turn round. Darwin’s text was evolving, adapting, in reaction to the ongoing debate it had triggered. For the sixth edition he included a whole new chapter, “Miscellaneous Objections,” answering one of his most aggressive critics point by point. This was the edition, too, for which Darwin struck the word “On” from his title, so that On the Origin of Species by Means of Natural Selection could henceforth be accurately shortened, in casual speech, to The Origin of Species.

  The sixth edition, published by Murray in 1872, was the last worked on by Darwin himself, and for that reason has often been taken as the authoritative text, the one people should read if they want to know what Darwin really, finally meant to say. In my non-expert opinion, this is misguided. The last version wasn’t necessarily the best, the most interesting, or the most significant. It wasn’t even, to revert to that problematic word, the most “Darwinian.” Not all the changes Darwin made to The Origin between 1859 and 1872 were improvements, and not all his improvements were as consequential as what he’d said, most daringly, in the book as first published. After thirteen years of extraordinary international hubbub, its main ideas had become widely known, from secondhand reportage and literary chatter as well as from the text itself. Those ideas were now swirling throughout the scientific communities of Britain, continental Europe, and America, and swirling also (more blurrily) in the public awareness, independent of whatever subtle revisions Mr. Darwin made for his latest edition. Evolution by natural selection was, by 1872, a bigger intellectual phenomenon than The Origin of Species, whereas in November 1859 the book was (with all due respect to Wallace) the definitive embodiment of the theory. Fiddle as he might with refinements, rebuttals, and adjustments of emphasis, Darwin wasn’t perfecting or undoing what he had initially done, whi
ch was to startle the world with a new way of seeing life on Earth.

  So my advice is, ignore the afterthoughts. Ignore the paperback reprints of the sixth edition. Trust no one; before you buy, before you read, check the small print in front under “Note on the Text,” or the discreet line of dating opposite the title page. Whether you turn to The Origin of Species as a scientific work or as a historical and literary document, do yourself and Charles Darwin a favor: Find a reprint (preferably a facsimile reprint, with the original typeface and pagination) of the first edition. That’s the book, with all its courageous freshness and its flaws, that provoked the most cataclysmic change in human thinking within the past four hundred years.

  33

  The book opens in a mild, unassuming tone of reminiscence:

  When on board H.M.S. ‘Beagle,’ as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers.

  The passage reads easily but there’s much alluded to: biogeography, paleontology, closely allied species adjacent in time. For the “mystery of mysteries” phrase from John Herschel, Darwin had dipped back into his transmutation notebook “E,” using an entry he’d made as an excited young man in December 1838. The part about throwing “some light” is a whopping understatement, which he will repeat to good effect, even more whoppingly understated, at the end of the book. Beyond touching those points, his other smart choice here is to come sailing into view—offering himself to our first impression—aboard the Beagle. It makes him seem personable and grounded in experience; back in 1859, it also reminded readers that this middle-aged theorist was the same fellow who, twenty years earlier, had delivered the popular travel narrative, Journal of Researches.

  Darwin’s six-page introduction, begun with that sentence, is a sort of overture in which he sounds his major themes: that “innumerable species inhabiting this world have been modified,” giving them amazing “perfection of structure and coadaptation,” and that the mechanism he calls “natural selection” can account for those modifications. He doesn’t use the word “evolution.” (That term appears nowhere in the first edition, though Darwin does conclude the book’s very last sentence by saying that many wondrous species “have been, and are being, evolved.”) The old, familiar, and provocative word “transmutation” is omitted here, too. Instead he talks in these opening pages about “modification and coadaptation” (and, later in the book, about “descent with modification” or his “theory of descent”). The other important theme announced in his introduction is the “struggle for existence,” the same phrase for the same idea that Alfred Wallace hit upon independently. And of course he mentions Malthus.

  Then he writes:

  As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.

  Add just two further ideas—that continued selection leads to prodigious extremes of adaptation, and also eventually to divergence of lineages—and this could stand as the abstract of the abstract.

  The main text is divided into fourteen chapters. The peculiar sequence of those chapters reflects a counterintuitive decision by Darwin: to discuss the mechanism by which evolution occurs before calling attention to the consequent phenomena. That is, he works first to persuade readers about natural selection—that it can happen and must happen, given variation and the struggle for existence. Only afterward does he offer evidence showing that evolution itself, by whatever mechanism, has happened. This may seem backward to us, but in 1859 it was shrewd, given that species transmutation was a familiar idea that had been proposed and rejected previously, whereas natural selection was the breakthrough concept that could make transmutation plausible, even irresistible, to skeptics.

  Darwin devotes his first chapter to variation among domestic animals and plants, noting how much of it routinely occurs, and how breeders use such small differences to transform lineages of livestock, pets, and crops. Dogs, cows, pigs, goats, strawberries, potatoes, dahlias, hyacinths, rabbits, sheep, horses, ducks—every domesticated species encompasses variation. One chicken, if you know your birds, is not quite like another. A good pig differs from a mediocre pig. And so also, of course, with pigeons—especially fancy pigeons, his favorite case. Drawing on the expertise gleaned from his own coops, his esoteric reading, and the London fanciers’ clubs he occasionally visited, Darwin argues that all pigeon breeds—the tumbler, the fantail, the pouter, and many others—are descended from one species of wild dove, Columba livia. What explains their extravagant forms of differentiation? The answer is selection, as practiced by humans. What explains racehorses versus dray horses, greyhounds versus bloodhounds? Again, selection by breeders. Nature somehow provides the small variations. Humans select preferred variations when they pair their animals or pollinate their plants. Those preferred variations are perpetuated—and magnified, through accumulation—over generations of domestic breeding. The result is specialized forms, differing from their ancestors in ways that people find useful or amusing. Artificial selection: the first leg of Darwin’s cardinal analogy.

  Then he turns to variation in the wild. “No one supposes that all the individuals of the same species are cast in the very same mould,” he says. Anyone who looks closely will admit that wild animals within any species, like domestics, differ slightly from one another. Wallace saw it among his boxes of beetles, birds, and butterflies collected for sale. Darwin saw it among his infernal barnacles. Variation is exactly what made taxonomy so damned difficult. But most people in 1859 assumed that such differences, among wild creatures, are limited and evanescent. Other naturalists besides Darwin and Wallace had noticed them, but considered them unimportant. If species are immutable, according to this view, then variations are minor wobbles around the archetypal essence of each species, to which every digression will eventually return. Varieties within a species are populations of such wobblers, insignificant and impermanent anomalies constrained by uncrossable boundaries of species identity.

  No, it isn’t so, says Darwin. Varieties can’t be so easily dismissed. In fact, even defining the two words—“species” and “variety”—is a tricky task. The tricky part is distinguishing one of those categories from the other, and the hardest thing about classifying specimens within such a category is that sometimes ambiguity can’t be resolved. Lines blur. Taxonomists disagree. One botanist will look at a large group of plants and see 251 species; another expert will look at the same group and see only 112 species, plus 139 false or trivial distinctions. From his Galápagos experience and the trouble afterward in classifying the birds, Darwin remembers being “much struck how entirely vague and arbitrary is the distinction between species and varieties.” The real distinction, he concludes, is this: a difference in degree. Species within a genus differ more than—but in the same ways as—varieties within a species do. The minor differences between varieties can accumulate, until they become the major differences between one species and another. It’s the very point that headlined Wallace’s 1858 paper, “On the Tendency of Varieties to Depart Indefinitely from the Original Type.” Darwin didn’t need to see that paper (and he certainly didn’t want to) because he had arrived at the same insight himself.

  These opening chapters represent Darwin’s direct assault on the old mode of thinking, which held species to be divinely created and fixed, like ideas stored in the file cabinet of God. The two chapters lay a groundwork for his discussion of natural selection
, but they do more. They deliver one of his most profound contributions to scientific thought. As the population geneticist Richard Lewontin has lately written: “Darwin revolutionized our study of nature by taking the actual variation among actual things as central to the reality, not as an annoying and irrelevant disturbance to be wished away.” He allowed us to see the living world as endlessly various. He helped us understand the whole physical universe as a realm of concrete contingencies, not imperfectly represented ideals.

  Chapter III is his treatment of the struggle for existence, using Malthusian arithmetic and empirical data to dispel the notion of nature in a state of divinely ordered tranquility. Nature’s real order isn’t peaceable; it’s a desperate scramble, even when the desperation is muted and obscure. Darwin alludes to a famous statement by the Swiss botanist A.-P. de Candolle, suggesting that “all nature is at war, one organism with another, or with external nature.” Predation, competition, parasitism, overcrowding. As species continue to procreate, there just isn’t enough food or enough space for their offspring. Reproductive rates are geometric. Habitat is finite. Fortunately, many dangers loom. If struggle and death didn’t sweep away most individuals of most species, the lands, seas, and skies would be impossibly full. Humans are relatively slow breeders, but the arithmetic holds true even for us: If we all bred and survived, doubling our population every generation, within a few thousand years there wouldn’t be standing room for another person on the planet. Elephants breed even more slowly. But their inherent rate of increase is geometric, too. A single female elephant, if she produced just six offspring in her lifetime, and if every descendant reproduced similarly, would in five centuries (according to Darwin’s rough calculation) yield a population of 15 million. That’s a lot of elephants. Too many. It doesn’t happen. Why not? Because every elephant must struggle—to survive, to reproduce—and many fail.