National Geographic : 2009 Feb
• himself that way, as time went on. But his theory developed slowly, secretively, and e Origin of Species (full title: On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life) didn t appear until 1859. Many scientists, along with some Victorian clergymen, resisted its evidence and arguments for decades a erward. e reality of evolution became widely accepted during Darwin s lifetime, but his particular theory--- with natural selection as prime cause---didn t triumph until about 1940, a er it had been suc- cessfully integrated with genetics. Apart from those clari cations, the most inter- esting point missed by the simpli ed tale is this: Darwin s rst real clue toward evolution came not in the Galápagos but three years before, on a blustery beach along the north coast of Argen- tina. And it didn t take the form of a bird s beak. It wasn t even a living creature. It was a trove of fossils. Never mind the notion of Darwin s nches. For a fresh view of the Beagle voyage, start with Darwin s armadillos and giant sloths. , during the rst year of its mission, the Beagle anchored near Bahía Blanca, a settlement at the head of a bay about 400 miles southwest of Buenos Aires. A certain General Rosas was waging a genocidal war against the Indians, and Bahía Blanca stood as a forti ed outpost, occupied mostly by soldiers. For more These clues from the Galápagos led Darwin (immediately? long a erward? here the mythic story is vague) to conclude that Earth s living diversity has arisen by an organic process of descent with modification---evolution, as it s now known---and that natural selection is the mechanism. He wrote a book called e Origin of Species and persuaded everyone, except the Anglican Church establishment, that it was so. Well, yes and no. is cartoonish account of the Beagle voyage and its consequences con- tains a fair bit of truth, but it also confuses, dis- torts, and omits much. For instance, the nches weren t as illuminating as the diversity of the islands mockingbirds, at least not initially, and Darwin couldn t make sense of them until a bird expert back in England helped. e Galápagos stopover was a brief anomaly near the end of an expedition devoted mostly to surveying the South American coastline. Darwin hadn t signed on to the Beagle as its o cial natural- ist; he was a 22-year-old Cambridge graduate pointed rather indi erently toward a career as a country clergyman, invited on the voyage as a dining companion for the captain, a mercurial young aristocrat named Robert Fitzroy. Darwin did assume the role of naturalist, and think of David Quammen is a National Geographic contributing writer. He wrote the December 2008 story on naturalist Alfred Russel Wallace. BY DAVID QUAMMEN THE DARWIN BICENTENNIAL PART ONE THE JOURNEY OF YOUNG CHARLES DARWIN aboard His Majesty s Ship Beagle, during the years 1831-36, is one of the best known and most neatly mythologized episodes in the history of science. As the legend goes, Darwin sailed as ship s naturalist on the Beagle, visited the Galápagos archipelago in the eastern Paci c Ocean, and there beheld giant tortoises and nches. e nches, many species of them, were distinguishable by di erently shaped beaks, suggesting adaptations to particular diets. e tortoises, island by island, carried di erently shaped shells.