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Why Darwin?

Charles Darwin: Voyaging

by Janet Browne
Knopf, 605 pp., $35.00

1.

Most young men of the time could only fantasize, but Charles Darwin experienced the overt drama of his century’s archetypal episode in the personal story we now call “coming of age”: a five-year voyage of pure adventure (and much science) circumnavigating the globe on H.M.S. Beagle. Returning to England at age twenty-seven, Darwin became a homebody and never again left his native land, not even to cross the English Channel. Nonetheless, his subsequent life included two internal dramas for more intense, far more portentous, and (for anyone who can move beyond the equation of swashbuckling with excitement) far more interesting than anything he had experienced as a world traveler: first, the intellectual drama of discovering both the factuality and mechanism of evolution; and second, the emotional drama of recognizing (and relishing) the revolutionary implications of evolution, while fearing the pain that revelation would impose upon both his immediate family and the surrounding society.

The Beagle years occupy (as they must) the central section of the three-part organization that Janet Browne has chosen for her long biography, which covers just the first part of Darwin’s life (until his decision, in the mid-1850s, to resolve the emotional drama and finally prepare his evolutionary views for publication). The second volume, now in preparation, will cover the publication of The Origin of Species in 1859, and Darwin’s amazingly productive life thereafter (he died in 1882). In this first volume, the first part covers birth to Beagle, the second the voyage itself, and the third Darwin’s rich English life in the twenty years between his return and his fateful decision.

Janet Browne is a leading historian of science and a central figure in what can only be called the “Darwin industry.” Her book deserves the adjectives of praise traditionally used by reviewers to describe masterpieces—all but one. It is wonderful and marvelous, even magisterial. But Browne’s book is not—because it cannot be—“definitive.” Too many Darwins dwelled within this enormously complex man—some up front but elusive in their superficiality, others elusive for reasons of concealment but inferable, thanks to Darwin’s obsessive habit of recording his thoughts and experiences. Still others may be truly hidden by Darwin’s selective internal editing according to Victorian standards. Moreover, scholars can evoke intellectual Darwins, psychological Darwins, sociological Darwins, family-minded, class-based, institutionally embedded, or ideologically framed Darwins—and each may be entirely satisfying. Any biography, to rank as a forceful and coherent statement, must choose one or only a few of these Darwins as a central subject—and all are both “true” and enlightening. No biography of Darwin, therefore, can possibly be definitive.

Browne’s two hundred pages on the Beagle voyage, chronicling the adventures of Charles Darwin as a vigorous and energetic young man (he exceeded six feet in height and could match anyone on board for physical endurance)—so different from our stereotypical image of Darwin in later life as a housebound invalid—are fascinating to read and provide the added bonus of documenting a brilliant man’s intellectual growth. But some twenty pages each on Darwin’s transition from doubting creationist to firm evolutionist, and on his tortuous formulation of the principle of natural selection (the intellectual drama) struck me as far more thrilling, both for exposing the depth of Darwin’s internal effort and distress, and for the impact upon human history wrought by his resolution of these dramas. The same could be said about the numerous paragraphs and sketches throughout the third part of the book on Darwin’s reticence about revealing himself (the emotional drama).

What could possibly be more exciting than the events of early 1837? Darwin has been home from his voyage for a few months, living in London, carefully making the right contacts, working on his Beagle specimens. He learns that his small Galapagos birds are all finches, and not members of several different families, as he had thought. He never suspected this result, and had therefore not recorded the separate islands where he had collected them. (Theory always influences our manner of collecting facts. As a creationist on the voyage itself, Darwin never imagined that the birds could have had a common source and then differentiated locally. According to the creationist view, all must have been created “for” the Galapagos, and the particular island of discovery therefore did not matter. But in any evolutionary reading, and with all the birds so closely related, their dwelling places now mattered intensely.) He therefore tries to reconstruct the data from memory. Ironically (in view of the depth of their later enmity over evolution), he even writes to Captain FitzRoy of the Beagle in order to get birds that his old boss had collected—and labeled much more carefully!

On March 14, his ornithological consultant, John Gould, presents a paper at the Zoological Society, showing that the small rhea, a large flightless bird, collected by Darwin in southern Patagonia, is a new species, and not merely a geographical variant as Darwin had thought. Gould heightened Darwin’s interest enormously by naming the bird Rhea darwinii. Browne now writes:

This moment more than any other in Darwin’s life…deserves to be called a turning point. Darwin was tantalized by the week’s results. Why should two closely similar rheas agree to split the country between them? Why should different finches inhabit identical islets? The Galapagos iguana, he was further told by Thomas Bell, similarly divided themselves among the islands, and the heavily built tortoises with their individualized shells again came to mind.

Darwin now made a key analogy. Has any truly brilliant insight ever been won by pure deduction, and not by metaphor or analogy? Darwin realized that the different species of finches and rheas each inhabited specific territories right next to the domain of another species. If both finches and rheas replace each other geographically, then shouldn’t temporal succession also occur in continuity—that is, by evolution rather than successive creation? Darwin had collected important and entirely novel fossils of large mammals. He thought, and his expert consultant Richard Owen had affirmed, that the fossils of one creature, later named Macrauchenia by Owen, stood close to the guanaco, a modern South American mammal closely related to the llama. Darwin had a key flash of insight and wrote in a small private notebook: “The same kind of relation that common ostrich [rhea] bears to Petisse [the new species Rhea darwinii], extinct guanaco to recent; in former case position, in latter time.”

Darwin had not become an evolutionist during the Beagle voyage, but he had fallen under the spell of the theory of gradualism and uniformity in the earth’s development, a view identified with his intellectual hero, the English geologist Charles Lyell. Darwin, at this stage of his career, was primarily a geologist, not a biologist. He wrote three books on geological subjects inspired by the Beagle voyage—on coral reefs, volcanic islands, and the geology of South America—but none strictly on zoology. Browne writes that Darwin

was convinced that the majestic story of nature could be explained by the accumulation of little things. Though clear enough to him through Lyell’s writings, this notion was given physical reality by Darwin’s geological researches in Chile and became the hub of all his later biological thinking.

Lyell, well apprised of Darwin’s beliefs and accomplishments, rejoiced at first in the prospect of a potential disciple, schooled in the field of nature. “How I long for the return of Darwin!” he wrote to Adam Sedgwick, Darwin’s old Cambridge geology teacher. Darwin and Lyell quickly became inseparable—in part as guru and disciple, in part simply as friends. Browne writes of Lyell:

Darwin was the first naturalist to use his “Principles” effectively: Lyell’s first, and in many ways his only fully committed disciple. “The idea of the Pampas going up at the rate of an inch in a century, while the western coast and Andes rise many feet and unequally, has long been a dream of mine,” Lyell excitedly scrawled to him in October. “What a field you have to write on! If you cannot get here for dinner, you must if possible join the evening party.”

In the crucial weeks after the return of the Beagle, then, Darwin had reached evolution by a double analogy: between geographic and temporal variation, and between geological and biological gradualism. He began to fill notebook after notebook with cascading implications. He numbered the volumes, starting with A for more factual matters of zoology, but describing a second set, M and N, as “full of metaphysics on morals and speculations on expression.” He drew a tree of life on one of the pages, and then had an attack of caution, writing with a linguistic touch from Beagle days: “Heaven knows whether this agrees with Nature—Cuidado [watch out].”

I tell this story at some length both for its intrinsic excitement, and to present an interesting tidbit that Browne, as a historian but not a paleontologist, may not know (or at least does not record)—and thus I may make one tiny contribution from my own profession. For those who still cherish the myth that fact alone drives any good theory, I must point out that Darwin, at his key moment of insight—making his analogy from geography to time and evolution—was quite wrong in his example. Macrauchenia is not, after all, an ancestor (or even a close relative) of guanacos, but a member of a unique and extinct South American mammalian group, the Litopterna. South America was an island continent, a kind of “Superaustralia” with a fauna even richer and more bizarre than Australia’s until the Isthmus of Panama rose just a few million years ago and joined the continent with North America. Several orders of large mammals, now extinct, had evolved there, including the litopterns, with lineages that converged by independent adaptation upon the horses and camels of other continents.

One may not wish to become as cavalier as Charles’s brother Erasmus, who considered The Origin of Species “the most interesting book” he had ever read, and who wrote of any factual discrepancy: “The a priori reasoning is so entirely satisfactory to me that if the facts won’t fit in, why so much for the facts is my feeling.” But beautiful (and powerful) theories are not killed by the “nasty, ugly little fact” of T.H. Huxley’s famous statement—nor should they be so destroyed in a recalcitrant world where reported “facts” so often turn out to be wrong. Fact and theory interact in wondrously complex, and often mutually reinforcing, ways. Theories unsupported by fact are empty (and, if unsupportable in principle, meaningless in science); but we cannot even know where to look without some theory to test. As Darwin wrote in my favorite quotation: “How can anyone not see that all observation must be for or against some view if it is to be of any service?” Evolution is powerful, integrating, and correct; whatever the historical interest in this tale, and despite the irony of the situation, it matters not a whit that Darwin’s crucial analogy, at his moment of eureka, resided in factual error.

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