Читать книгу The Tangled Tree: A Radical New History of Life - David Quammen, David Quammen - Страница 14

It was a perplexingly long delay, almost two decades, between the writing of those four lines in his secret E notebook and the first public announcement of Darwin’s theory. Longer still, twenty-one years, to publication of the theory in book form—On the Origin of Species appeared in November 1859. The reasons for that delay, which were both scientific and personal, both anxious and tactical, have been minutely examined in other works (including some of mine). We can skip over them here except to note that, when Darwin finally went public with his theory, it was because a younger naturalist had forced his hand by coming forward with the same idea.

Alfred Russel Wallace, after four years of fieldwork in the Amazon and four more in the Malay Archipelago, had hit upon the notion of natural selection (framed in his own language, not that pair of words) and written it up in a short paper. As recounted by Wallace long afterward, the idea came during a layover in his collecting travels through the northern Moluccas. He suffered a bout of fever (maybe malarial), and, amidst it, he had this extraordinary insight. Variation plus overpopulation, minus the unsuccessful variants, would yield heritable adaptation. When the fever broke, and the sweat dried, and the dreamy brainstorm still seemed cogent, Wallace composed his manuscript and then tried to get it considered.

But he was a poor man’s son, working his way through the tropics by selling decorative specimens—bird skins, butterflies, pretty beetles—not a gentleman traveler as Darwin had been on the Beagle. Wallace wasn’t well educated or well connected. He knew almost nobody in the higher circles of British or European science, and almost nobody in those circles knew him—not face-to-face and not as a peer, anyway. He was a collector of dried creatures for pay, a natural-history tradesman. There was class stratification in science as in every other part of Victorian British society. But he had published a few earlier papers in a respectable journal, and one of those papers had drawn favorable attention from Charles Lyell, the great geologist. Oh, and Wallace knew one other famous man, not personally but as a sort of pen pal, who had spoken generously to him in a letter: Charles Darwin.

It was now February 1858. Hardly anyone at that point recognized Darwin for what he was—an evolutionary theorist, in secret—and though Lyell was among that small group who did, as a close friend and confidant, Alfred Wallace certainly wasn’t. Charles Darwin to him was just a conventionally eminent naturalist, author of the Beagle chronicle and other safe books, including several on the taxonomy of barnacles. But a Dutch mail boat would soon stop at the port of Ternate, in the Moluccas, where Wallace had fetched up. He was excited by his own discovery, if it was a discovery, and eager to share this dangerous hypothesis with the scientific world. So he packed up his paper with a cover letter and mailed the packet to Mr. Darwin, hoping that Darwin might find it worthy. If so, maybe Darwin would share it with Mr. Lyell, who might help get it published.

The packet reached Darwin, probably on June 18, 1858, and hit him like a galloping ox. He felt crushed, scooped, ruined—but also honor-bound to grant Wallace’s request, passing the paper on toward publication. It would mean, Darwin knew, letting the younger man take all the credit for this epochal idea he himself had incubated for twenty years but was not yet quite ready to publish. Despite that, he did send the Wallace paper along to Lyell—communicating yelps of his own anguish along with it. Lyell took not just the paper but also the hint. Along with another of Darwin’s close scientific allies, the botanist Joseph Hooker, Lyell talked Darwin back from despair, suggested a posture of sensible fairness rather than self-abnegating honor, and brokered a compromise of shared credit. The result was a clumsily conjoined presentation—a pastiche of Wallace’s paper plus excerpts from Darwin’s unpublished writings—before a British scientific club, the Linnean Society, in the summer of 1858. Lyell and Hooker offered an introductory note, and then simply watched and listened. Proxies read the works aloud, with neither of the authors present. (Darwin was at home, where his youngest son had just died of scarlet fever; Wallace was still out in the far boonies of the Malay Archipelago.) This joint presentation made almost no impression on anyone, not even the few dozen Linnean members in attendance, because the night was hot, the language was obscure, the logic was elliptical, and the big meaning didn’t jump forth.

Seventeen months later, Darwin published On the Origin of Species. That 1859 book, not the 1858 paper or excerpts, launched the Darwinian revolution. It was only an abridged and hasty abstract of the much longer (and more tedious) book on natural selection that Darwin had been writing for years, but The Origin was just enough, in the right form, at the right time. It presented the theory as “one long argument,” not just a bare syllogism, and with oodles of data but not many footnotes. It was plainspoken, and readable by any literate person. It became a bestseller and went into multiple editions. It converted a generation of scientists to the idea of evolution (though not to natural selection as the prime mechanism). It was translated and embraced in other countries, especially Germany. That’s why Darwin is still history’s most venerated biologist and Alfred Russel Wallace is a cherished underdog, famous for being eclipsed, to the relatively small subset of people who have heard of him.

The crux of the “one long argument” comes in chapter 4 of The Origin, titled “Natural Selection,” in which Darwin describes the central mechanism of his theory. It’s the same combination of three principles that he had scratched into his notebook two decades earlier, plus the turned crank. “Natural selection,” he wrote in the book, “leads to divergence of character and to much extinction of the less improved and intermediate forms of life.” Lineages change over time, he stated. You could see that in the fossil record. Different creatures adapt to different niches, different ways of life, and thereby diversify into distinct forms and behaviors. Transitional stages disappear. Then he wrote: “The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth.”