The Tangled Tree: A Radical New History of Life. David Quammen

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hundreds of plants, beautifully illustrated and arranged in alphabetical order. Two centuries later, the great systematizer Carl Linnaeus described a genus of plants with purplish red flowers, naming it Fuchsia in honor of Leonhart Fuchs (and hence we got also the color, fuchsia). Linnaeus himself, a Swede who traveled widely as a young man and then took up a professorial life in Uppsala, emerged from this herbalist tradition but went beyond it.

      Augier’s Arbre Botanique, 1801.

      Linnaeus’s Systema Naturae, as first published in 1735, was a unique and peculiar thing: a big folio volume of barely more than a dozen pages, like a coffee-table atlas, in which he outlined a classification system for all the members of what he considered the three kingdoms of nature: plants, animals, and minerals. Notwithstanding the inclusion of minerals, what matters to us is how Linnaeus viewed the kingdoms of life.

      His treatment of animals, presented on one double-page spread, was organized into six columns, each topped with a name for one of his classes: Quadrupedia, Aves, Amphibia, Pisces, Insecta, Vermes. Quadrupedia was divided into several four-limbed orders, including Anthropomorpha (mainly primates), Ferae (doggish forms such as wolves and foxes, plus cat forms such as lions and leopards, in addition to bears), and others. His Amphibia encompassed reptiles as well as amphibians, and his Vermes was a catchall group containing not just worms, leeches, and flukes but also slugs, sea cucumbers, starfish, barnacles, and other sea animals. He divided each order further into genera (with some recognizable names such as Leo, Ursus, Hippopotamus, and Homo), and each genus into species. Apart from the six classes, Linnaeus also gave a half column to what he called Paradoxa: a wild-card assemblage of mythic chimeras and befuddling but real creatures, including the unicorn, the satyr, the phoenix, the dragon, and a certain giant tadpole (Pseudis paradoxa, under its modern label) that, strangely, paradoxically, shrinks during metamorphosis into a much smaller frog. Across the top of the chart ran large letters: CAROLI LINNAEI REGNUM ANIMALE. His animal kingdom. It was a provisional effort, grand in scope, integrated, but not especially original, to make sense of faunal diversity based on what was known and believed at the time. Then again, animals weren’t Linnaeus’s specialty.

      Plants were. His classification of the vegetable kingdom was more innovative, more comprehensive, and more orderly. It became known as the “sexual system” because he recognized that flowers are sexual structures, and he used their male and female organs—their stamens and pistils, those delicate little stems sticking up to present and receive pollen—for characterizing his groups. Linnaeus defined twenty-three classes, into which he placed all the flowering plants, based on the number, size, and arrangement of their stamens. Then he broke each class into orders, based on their pistils. To the classes, he gave names such as Monandria, Diandria, and Triandria (one husband, two husbands, three husbands), and, within each class, ordinal names such as Monogynia, Digynia, and Tryginia (numbers of wives, yes, you get the idea), thereby evoking all sorts of polygamous and polyandrous ménages that must have caused lewd smirks and disapproving scowls among his contemporaries. A plant of the Monogynia order within the Tetrandria class, for instance: one wife with four husbands. Linnaeus himself seems to have enjoyed the sexy subtext. And it didn’t prevent his botanical schema from becoming the accepted system of plant classification throughout Europe.

      Our man Augustin Augier, coming along a half century later with his botanical tree of classification, seems to have seen himself challenging Linnaeus’s overly neat sexual system. “Stamen number is a striking character,” Augier conceded, but “not when it comes to the examination of plants”—that is, not always unambiguous and therefore not reliable as a basis for organizing the great jumble of botanical life. He nodded respectfully to Linnaeus—also to the French botanist Joseph Pitton de Tournefort, who had sorted plants into roughly seven hundred genera based on their flowers, their fruits, and other bits of their anatomy—and offered his own system, using multiple characters for different levels of sorting and to resolve the ambiguities and fine gradations. “This figure, which I call a botanical tree, shows the agreements which the different series of plants maintain amongst each other, although detaching themselves from the trunk; just as a genealogical tree shows the order in which different branches of the same family came from the stem to which they owe their origin.” All discrete, yet all connected: bits of the same tree.

      But they weren’t connected, in Augier’s mind, by descent from shared ancestors. Despite the hint he gave to himself in his language about family trees—all branches divergent from “the stem to which they owe their origin”—there is no evidence in Augier’s writing or his tree figure that he had embraced, or even imagined, the idea of evolution.

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      That idea was coming soon, and, with its arrival, the tree of life would change meaning. The change was drastic, soul shaking to many people who lived through it, because it reflected a challenge to faith, and it met strong resistance. Jean-Baptiste Lamarck, France’s great early evolutionist, and Edward Hitchcock, an American who prided himself a “Christian geologist,” are the two scientists whose works—and whose graphic illustrations—best reflect how tree thinking shifted during the decades before Darwin unveiled his theory of evolution.

      Lamarck was a protean figure: a soldier from a family of soldiering minor nobility who transformed himself into a botanist, then into a professor of zoology at the Muséum National d’Histoire Naturelle in Paris, to which he was appointed in 1793, on the eve of the Reign of Terror. His title at the museum put him in charge “of insects, of worms, and microscopic animals,” three categories of life he had never studied, but he adapted fast, and even invented the word invertebrates to cover them. He abandoned plants and studied his invertebrates through the grimmest days of the French Revolution, earning a measly salary but at least keeping his head, as other scientists such as Antoine-Laurent Lavoisier went to the guillotine. Lamarck had probably helped his standing among the revolutionaries back in 1790 while employed at what was then the Jardin du Roi, when he urged dropping the royal label and renaming that institution the Jardin des Plantes. Clearly, he had good political instincts. He held the conventional view of species—that they were fixed forever and created by God—until 1797, but then his views changed, possibly as a result of his study of fossil and living mollusks, which seemed to show patterns of gradual transformation. He came out as an evolutionist on May 11, 1800, in his first lecture for the year’s course on invertebrates. After that, he published three major works on evolutionary zoology, the most influential being his Philosophie Zoologique in 1809.

      Lamarck outlived four wives and three of his seven children, living beyond the revolution, through the Napoleonic era and most of the Bourbon Restoration, a handsome man with a downturned mouth, balding slowly across his pate, blind for his final ten years, his faithful daughter, Cornelie, giving her life to him and reading him French novels. He died at eighty-five and was eulogized by important colleagues such as Geoffroy St. Hilaire, after which things didn’t go so well: his remains were interred at the Montparnasse Cemetery in a common trench, not a permanent individual plot, and because such burial trenches were regularly recycled, his bones may have ended up in the Paris catacombs, along with those of thousands of paupers and other neglected folk. There was no Lamarck grave to visit. He became, according to one biographer, rather quickly “forgotten and unknown.” His fame would return, if not immediately, but still it was a cold finish for the world’s first serious evolutionary theorist.

      Lamarck

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