The Reluctant Mr. Darwin (20 page)

Just what makes rudimentary organs shrink away? That's a complicated issue—more complicated than even Darwin knew. He suspected that
disuse
of such organs is sufficient cause; but modern evolutionary theory (and I'll come back to this) says he was wrong. Okay, nobody's perfect. Charles Darwin certainly wasn't. He had an appendix, he had nipples, none of which served any useful purpose, and he occasionally made mistakes, even in
The Origin of Species
. Anyway, whatever impels the deterioration of elaborate organs into rudiments, the result is a record of evolutionary change.

In his final chapter, Darwin declares that the entire book is essentially “one long argument” linking the idea of common descent to the idea of natural selection. After recapitulating his main facts and inferences, he rises to a rhetorical crescendo, forecasting accurately that his theory will ignite “a considerable revolution in natural history.” The job of systematists, given this new perspective, will become easier and less ambiguous. Fresh inquiries will be opened into the causes and laws of variation. Natural history will be altogether more interesting. The study of domesticated species will gain value. Paleontology will be clarified, biogeography will advance, embryology and the scrutiny of rudimentary organs will reveal connections between living species and ancient prototypes. “In the distant future,” Darwin writes, “I see open fields for far more important researches.” Psychology, for example—the origin of mental powers will be understood in an entirely new way. And then he lets drop his most famously coy remark: “Light will be thrown on the origin of man and his history.” Still being cautious, even in his revolutionary manifesto, Darwin says nothing more—for now—about human evolution.

Instead he shifts to another touchy subject: the ways of God. Many eminent authors, he admits, are satisfied to believe that each species has been specially created. Not Darwin. “To my mind it accords better with what we know of the laws impressed on matter by the Creator,” he declares, “that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual.” There's a big theme, and a deep conviction, buried in that phrase about “
laws impressed on matter
”—bigger and deeper even than the subject of evolution. Darwin believed that the universe was governed by fixed laws, not by capricious divine interventions. He was still enough of a theist, at least in 1859, to write of “the Creator” as ultimate source of those laws, but his whole intellectual life was grounded in the confidence that such laws were discoverable and unchanging. He hinted as much, back at the start of
The Origin
, with a small quotation from William Whewell placed as an epigram opposite his title page:

Now, in the book's final paragraph, Darwin returns to that big theme. Think of evolution as the result of fixed laws, he urges: like gravity, or the movement of heat. Evolution's governing laws include biological growth, reproduction, inheritance, variation, population pressure, and the struggle for existence, all combining to yield natural selection, divergence, and the extinction of less adapted forms. From the war of nature comes an exalted result: the higher animals. Isn't that a more satisfying and majestic notion than requiring God personally to design every tick, clam, and flatworm?

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 that view. It's an eloquent conclusion to a magnificent, hastily composed, compelling, and seriously flawed book.

35

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.