The Reluctant Mr. Darwin
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To Darwin it is. “There is grandeur,” he says finally, echoing phrases he first drafted for his 1844 essay, “in this view of life….” The full, closing passage of The Origin is famous, but worth quoting again:
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
There is grandeur in that view. It’s an eloquent conclusion to a magnificent, hastily composed, compelling, and seriously flawed book.
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Closely rereading The Origin of Species, with less attention to the core of its argument and more attention to the author’s voice, to his style of logic, to his omissions and mistakes, to the scope of his claims, helps put his accomplishment into perspective. A bit of modestly critical scrutiny reveals, without disrespect to what Darwin achieved, that this great book is not great on every page and in every way.
One of its defects is Darwin’s incessant apologizing for the fact that The Origin isn’t three times longer. “This Abstract, which I now publish, must necessarily be imperfect,” he writes in the introduction. “I cannot here give references and authorities for my several statements.” We’ve heard that before, in the anxious letters to his friends: Woe and alas, my stinking book, it’s just a miserable abstract, squashed and inadequate. But now he’s making a public excuse, not just fretting privately, and Darwin frames the excuse in a disingenuous form. “I much regret that want of space,” he says on page 2, “prevents my having the satisfaction of acknowledging the generous assistance…” et cetera. The italics are mine. “If I had space,” he claims later (again, my italics), “I could quote numerous passages to this effect” (never mind, about what) “from highly competent authorities.” Later still, making a different point: “…but I have not space here to enter on this subject.” So it’s “want of space” that’s the problem?
Actually, no. Darwin was free to take as much space as he needed. Page limits had been a genuine concern earlier, true enough—during the first months of composition, when he imagined that his abstract might be publishable as a journal article. Then he overflowed those limits and, making a tactical choice, decided that it must be a book. Midway through the writing, in late 1858, he projected that his volume would fill 400 pages, a rough guess later revised to 500. John Murray, his publisher, never specified any limit. But in the 1859 text as we find it published, he can’t stop complaining about his self-imposed constraints. “I could show by a long catalogue of facts…”—yet he doesn’t. “I shall reserve for my future work the discussion of these difficulties…”—but that work, the big book, never came. About comb-building behaviors among honey bees, he writes, “if I had space, I could show that they are conformable with my theory.” Throughout the book he repeats that lament: Can’t give details, sorry. Maybe later. The pretext, when he offers one, is: No space. What was Darwin really fussing about?
Not a shortage of space but a shortage of time. Alfred Wallace had scared the bejesus out of him, he knew he’d delayed too many years, and now he felt desperately rushed to get his book into print. Dignity prevented him from admitting that.
Another quirk in The Origin is the extent to which his “one long argument” relies on probability and personal attestation. Taken properly within its philosophical context—the context of inductive science, as it had lately been outlined by Whewell, among others—this should probably be seen as a strength of the book, not a weakness. Darwin doesn’t claim to prove the reality of evolution by natural selection. In fact, “proof” is a word that he seldom uses—and when he does, it’s often negatively, to acknowledge some intractable ambiguity. About the notion that embryology gives glimpses of evolutionary lineage: “This view may be true, and yet it may never be capable of full proof.” About the idea, sometimes asserted, that variation in the wild has strict limits: “the assertion is quite incapable of proof.” More important, Darwin understands that good inductive science (which had become the ideal by the time he was writing) can never, unlike mathematics, prove a result beyond any logical possibility of doubt. Instead of claiming to prove his big theory, he moves the reader toward it persuasively by way of accreting evidence. The goal is to show that his hypothesis explains a larger and more interconnected collection of data, with greater probability, than any alternative hypothesis. Along the way, Darwin makes statements such as “I think it highly probable that” and “I am convinced that,” buttressing the evidence with his own amiable persona as a fair-minded English gentleman to suggest that these conclusions can probably be taken as right.
This is a point with some relevance, in our own time, to the conflict between evolutionism and creationism. It’s an arid truth, but one that the defenders of evolutionary theory (and the teaching of it in public schools) against religion-based political challenges would do well to remember. The complexities of epistemology, as well as those of biology, shouldn’t get lost in the arguing. No, you can’t prove that all species have evolved from common ancestral lines, with natural selection as a major driving mechanism, and Charles Darwin himself didn’t claim that you could. It’s just very, very probable that this explanation of the living world is correct, based on the evidence Darwin mustered and all that’s been added since. The alternative explanations are either less probable within the realm of physical cause and effect, or else they’re scientifically meaningless (because untestable against negative data) expressions of religious belief.
Besides lacking any claim of absolute certainty, The Origin is marked by some other notable omissions. As I’ve mentioned, it lacks the word “evolution.” (That term carried undesirable connotations, in 1859, related to a sort of mystical unfolding or unrolling of forms.) It lacks a good explanation for the source of those crucial variations upon which selection acts. It lacks an unambiguous statement about whether such variations are haphazard or somehow directionally evoked. (The adjective “random” appears nowhere in the book, and to say that variations result from “chance” is, as Darwin admits, misleading. He does imply, though, that they are undirected.) Despite its attention to the principle of divergence, it lacks clarity on the key matter of how speciation—as distinct from adaptation—occurs. (When two populations of a species diverge from each other, what factor accounts at a certain point for their irreversible separation into two species?) It lacks insight into the mechanics of inheritance—the vital matter of how selected variations are passed along. Finally, the book lacks any explicit assertion that we humans share an ancestor with apes.
One thing the book doesn’t lack is the idea that acquired characteristics can be inherited. Although that idea is sometimes considered synonymous with Lamarckism, it actually predated Lamarck’s work and remained more enticing than the Frenchman’s other propositions. In Darwin’s plain language, it sounds concrete and sensible: the “effects of use and disuse.”
“I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts,” he writes in The Origin, “and disuse diminishes them; and that such modifications are inherited.” Furthermore, it’s not just domestic animals that show this trait, he says; wild ones do, too. “I believe that the nearly wingless condition of several birds, which now inhabit or have lately inhabited several oceanic islands, tenanted by no beast of prey, has been caused by disuse.” The dodo of Mauritius, the cassowaries of New Guinea, the emus of Australia, and of course the kiwi, all surrendered their wings to this principle, he thought. Use ’em or lose ’em. A giraffe, in his view, contrary to Lamarck’s (as Darwin construed it), couldn’t simply will its way to a longer neck; but by the habit of stretching for high food, it could add increments of length, and those increments (here’s his mistake) could be inherited. Muscles of a blacksmith, likewise. By their efforts and habits, individual creatures earn bodily improvements…
and they can pass those improvements along to their offspring, Darwin believed.
These confusions and omissions suggest some of the unfinished scientific business remaining for Darwin, and for his acolytes and successors, when The Origin of Species first appeared. Darwin himself understood that this book he’d dashed off wasn’t perfect. Although he foresaw a revolution in natural history, he recognized that his “abstract” was just the opening salvo, not the declaration of final settlement terms. He knew that the work of what we now call evolutionary biology had only started, and he meant to stay engaged as it progressed. He was still struggling to comprehend variation. He wanted an explanation of heredity. He intended to address the hot topic of human origins.
Meanwhile the book made him famous—far more famous than he’d been as a conventional naturalist and writer—and profoundly controversial. It was translated (badly and irresponsibly, in some cases, by foreign thinkers with their own agendas), published abroad in authorized and unauthorized editions, widely reviewed, admired, denounced, released in a cheap edition by Murray for a bigger market, and talked about by many more people than actually read it. It sold roughly 25,000 copies, of the English editions alone, during Darwin’s lifetime. “The real triumph of Darwin’s book came after his death,” according to Morse Peckham, editor of the variorum text. “The profits of the American pirates must have been enormous.” Those numbers are unavailable, as are totals reflecting the book’s global reach. A bibliographical checklist, published in 1977, recorded 425 distinct editions of The Origin of Species (not counting reprints of each edition) just to that point, including four in Hungarian, two in Hebrew, two in Romanian, two in Latvian, four in Korean, one in Hindi, and fifteen in Japanese. Darwin himself devoted a sizable share of his energies, over the dozen years following first publication, to revising it, promoting it (he mailed off quite a few complimentary copies), monitoring its reception (yes, he read his reviews), and playing his role (mainly by letter) in the scientific discussion it provoked. The book succeeded hugely in some ways, and failed in others. It made evolution seem plausible. But it left many of Darwin’s scientific colleagues—never mind lay readers and religious critics—unwilling to accept natural selection as the mechanism. That idea was still too big, too scary, too cold.
For better and worse, with its flaws and its majesties, The Origin of Species stands as Darwin’s ultimate statement of his theory, and the 1859 edition articulates that statement most freshly and boldly. It was never supplanted by the encyclopedic tome, Natural Selection, that he had intermittently intended to write. Through those five later editions of The Origin, he continued monkeying with his text, sometimes improving it but often just adding confusion, caution, and unnecessary words. By 1869, he sounded weary of that. “If I lived twenty more years and was able to work, how I should have to modify the Origin,” he confided to his dear old friend Hooker—and then, changing moods, mustering resoluteness, “how much the views on all points will have to be modified!” But he wouldn’t live twenty more years. Nor did he expect to. So he sighed: “Well, it is a beginning, and that is something….”
It was something indeed: less than the book he had hoped to write, but more than enough to cause a ruckus.
The Fittest Idea
1860 to the future
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Most people today don’t realize that natural selection, Darwin’s greatest and most troubling idea, fell into disfavor among evolutionary biologists for fifty or sixty years. Most people imagine that the Darwinian revolution, so called, was a relatively quick campaign fought and won in the late nineteenth century. It wasn’t. It was an up-down-up scuffle for decades.
There were two principal questions, contested almost independently: (1) Has evolution occurred? and (2) Is natural selection its main causal mechanism? Despite some horrified outcries from religious leaders and pious scientists, the descent of all species (even humans) from common ancestors became widely accepted rather soon after The Origin of Species was published. Despite his careful arguments in the first half of the book, Darwin’s hypothesis as to the causal mechanism did not. Why not? Because the idea of natural selection seemed profoundly materialistic and gloomy—that is, it was both literally and figuratively dispiriting—whereas the idea of evolution seemed merely insulting (as applied to the human species) and bizarre. Evolution contradicted William Paley’s natural theology, as propounded in 1802, yes; but Paley’s natural theology was an ingenuous, prescientific vision that had outlived its time (except in America, where it returned during the late twentieth century under the label “Intelligent Design”) and was soon supplanted by the idea that species, rather than being individually created by God, had somehow evolved one from another. Natural selection struck deeper, undermining the whole notion of godly purpose. Evolution could be reconciled with belief that a divine Creator had established laws governing the universe, had set life into motion, had allowed species to change over time, and then—at some magical moment—had injected a unique spiritual dimension into the primate species that was later to be known (by its own self-naming) as Homo sapiens. Natural selection, on the other hand, seemed to preclude that belief. It did, anyway, if taken strictly and seriously—the way Charles Darwin took it.
The crux of the matter was not natural selection itself but the variations upon which it works. What causes those small differences between parents and offspring, and between one competing individual and another, which serve as the raw material for adaptive change? What laws govern their scope, rate of occurrence, and character? Are they purely random, or somehow constrained by limits of physical possibility—or are they, maybe, directed toward certain purposes by a higher power? If variations are random, then purposefulness (the philosophers of science call it teleology) disappears from the living world. Gone, zero, zip.
Whoa. That’s a large step into darkness. No higher purpose to the vast pageant of life and death? No higher purpose to Herschel’s “mystery of mysteries,” the first appearance of new species? No higher purpose behind adaptation and diversification, the processes whereby simplicity gives way to complexity on a spectrum from primal ooze to humans? These were implications that Darwin’s nineteenth-century audience found difficult to accept. They’re still difficult to accept. But this generalized loss of teleology is abstract and impersonal. It’s not the source of keenest discomfort with natural selection. Another corollary of the theory is more acutely problematic: loss, for the human species, of our own special status as God’s chosen.
Is there a glorious end for which evolution has produced mankind? Are humans in any sense uniquely ordained? Did the deity foresee we were coming and somehow will it? Or are we merely the most well adapted, cerebral, and successful species of primate that has ever lived? Beneath those questions lies one deeper question about the variations from which natural selection has shaped Homo sapiens: What is their source?
Darwin proposed in The Origin that variations occur in response to “conditions of life”—that is, external stresses such as severity of climate, food shortage, or habitat disturbance, which somehow unsettle the reproductive system. It was a calculated guess. Elsewhere in the book, he admitted: “Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part differs, more or less, from the same part in the parents.” Scholars have noticed this lacuna: His theory depends on variations, but there’s no good account of their origin in The Origin. He just didn’t know where they came from, nor how. At the time, no one did.
Puzzled as Darwin was about their source, he strongly suggested that variations are, overall, directionless. That is, they go here and there, haphazardly. They are scattershot, not aimed. The point is so crucial, and the language by which he addressed it so tricky, that it deserves a moment’s special attention. Back in 1844, in his unpublished 189-page draft of the theory, Darwin had written that variations occur “in no determinate way.” Earlier still, in one of his notebook jottings,
he had described them as “accidents.” He wrote in The Origin of “chance” variations, then noted elsewhere in the book that to say they are “due to chance” is an incorrect expression, a convenience of speech that merely “serves to acknowledge plainly our ignorance of the cause” of each one. It’s an incorrect expression, he meant, in that variations do have physical causes; they just don’t have preordained purposes. For instance, a drought might increase the rate of variation in a species, he thought, without necessarily evoking any particular variations that improve a creature’s tolerance for drought. Or the drought might yield one variation for drought tolerance plus five others that are useless or harmful. If so, natural selection would tend to preserve and multiply that one. Selection is directional; variation, offering raw material to the selection process, is not directional.
But if variations are undirected, and if natural selection calibrates only the fitness of each individual creature to survive and reproduce, then is it possible to believe that God created humans in His image and likeness, endowing us with a spiritual dimension not shared by the best-adapted orchid or barnacle? Arguably not. There’s a genuine contradiction here that can’t easily be brushed away. But let’s be clear: This is not evolution versus God. The existence of God—any sort of god, personal or abstract, immanent or distant—is not what Darwin’s evolutionary theory challenges. What it challenges is the supposed godliness of Man—the conviction that we above all other life forms are spiritually elevated, divinely favored, possessed of an immaterial and immortal essence, such that we have special prospects for eternity, special status in the expectations of God, special rights and responsibilities on Earth. That’s where Darwin runs afoul of Christianity, Judaism, Islam, and probably most other religions on the planet.