Free The Reluctant Mr. Darwin by David Quammen Page B

medicine, in Paris, he made himself a botanist, publishing an excellent three-volume flora of France. The book was well received but didn’t solve Lamarck’s problem of making a living, so he served two years as tutor and traveling companion to Buffon’s son. Then he got himself hired as a botanical assistant, for a measly salary, at the Jardin des Plantes (which was later subsumed within the Musée National d’Histoire Naturelle). Lamarck’s next metamorphosis, the most drastic one, didn’t happen quickly. After twenty-five years as a botanist, he shifted to zoology, taking a museum position as professor of invertebrate animals and managing, throughout the Terror phase of the French Revolution, to keep his head down and away from the guillotine. His job was to lecture on insects, worms, and microscopic animals. Several years later the museum’s mollusk collection fell into Lamarck’s care when the malacologist, a friend of his, died. Studying that material, an assortment of fossils and recent shells, he saw evidence of variation within species and of sequential similarities among species found adjacent to one another in the column of time.
    Abruptly, for whatever reasons, at the age of about fifty-five, Lamarck lost his belief in the immutability of species. Soon afterward, in May 1800, he gave his first lecture with an evolutionary slant. He presented his full theory nine years later in Philosophie zoologique , the book from which it’s mainly known. A refined version appeared still later, in the introduction to his seven-volume natural history of invertebrates. Lamarck outlived four wives, went blind, survived to the age of eighty-five under the care of an unmarried daughter, struggled financially the whole way, and died in 1829, at which point he was more admired by radical British evolutionists (such as those teaching anatomy to medical students in Edinburgh and London) than by his colleagues in France. He was buried cheaply in an unmarked grave, like Mozart.
    Most people, if they know anything about Jean-Baptiste Lamarck, associate him with a single idea: the inheritance of acquired characteristics. There was more, as Darwin’s groaning dismissal of what he considered Lamarckian nonsense (“tendency to progression” “adaptations from the slow willing of animals”) in the letter to Hooker reflects. Lamarck argued that two factors account for evolution. One is, as Darwin noted, an inherent tendency in living creatures to progress from simple forms toward complexity. This tendency is conferred on them, Lamarck thought, by “the supreme author of all things.” The simple forms originate by spontaneous generation. The increasing complexity comes as certain “subtle fluids” somehow open new channels through body tissue to create new and more intricate organs. Lamarck didn’t explain why the progressive tendency exists, or just how those precious bodily fluids do their magic. He treated this factor as a given. It yielded separate lineages, progressing independently toward more complex species—but not to a branching tree of life. That’s an important distinction to keep in mind: Lamarck never proposed that all creatures are descended from common ancestry. The right image for his theory would be prairie grass, with short stalks and long stalks rising parallel from the ground, not a bush or a tree with divergent branches, like the drawing in Darwin’s “B” notebook.
    Lamarck’s second factor, which is more materialistic than his supposition of a God-given tendency to progress, encompasses four elements. First, animals face certain pressures from the external conditions (that is, the environment) within which they live. Second, when external conditions change, animals have new needs ( besoins ); they respond to those needs by increased use of certain organs or capacities, or by neglecting to use those they’ve been using.