Shadows of Forgotten Ancestors

Erasmus Darwin believed that “There are three great objects of desire, which have changed the forms of many animals by their exertions to gratify them: hunger, security and lust.” Especially lust. The lilting refrain of his last effort, The Temple of Nature: or, The Origin of Society,⁵ was “And hail THE DEITIES OF SEXUAL LOVE.” The capitalization is his. Elsewhere, he observed that the stag had developed horns to fight other males for “the exclusive possession of the female.” There’s no question that he was on to something. But his was a kind of disordered originality, a brilliance that could not be bothered by methodical research. Science exacts a substantial entry fee in effort and tedium in exchange for its insights. Erasmus was unwilling to ante up.

His grandson Charles, who would pay those dues, read Zoonomia twice; once when he was eighteen and again a decade later, after he’d been around the world. He took pride in his grandfather’s precocious anticipation of some of the ideas that would make Jean-Baptiste de Lamarck famous twenty years later. However, Charles “was much disappointed” by Erasmus’ failure to investigate, carefully and rigorously, whether there was any truth to his inspired speculations

Lamarck had been a soldier, a self-taught botanist, and the zoologist who had gone on to develop the precursor of the modern natural history museum. When everyone else was thinking in terms of thousands of years, he was contemplating millions. He believed that the idea of the living world walled up into separate compartments called species was an illusion; species are slowly transmogrifying, one into another, he taught, and this would be immediately apparent to us if our lives were not so brief and fleeting.

Lamarck is best known for arguing that an organism could inherit the acquired characteristics of its ancestors. In his most famous example, the giraffe strains to nibble at the leaves on the higher branches of the tree, and somehow the slightly elongated neck that attends the stretching is passed on to the next generation. Lamarck could not have been knowledgeable of the family history of many generations of giraffes, but he did have relevant data that he chose to ignore: For thousands of years, Jews and Moslems have been ritually circumcising their sons, with no break in continuity, and yet not one case is known of a Jewish or Islamic boy born without a foreskin. Queen bees and drones do no work, and have not for geological ages; yet worker bees whose parents are queens and drones (and never other workers) do not seem to be growing more indolent, generation after generation; instead, they are proverbially industrious.⁶ Domestic and farm animals have their tails docked, their ears clipped, or their flanks branded for generations, but the newborn show no signs of these mutilations. Chinese women had their feet cruelly bound and deformed for centuries, but infant girls obstinately persisted in being born with normal appendages.⁷ Despite such counterexamples, Charles would take seriously, for his entire life, the notion of Lamarck and his grandfather Erasmus that acquired characteristics could be inherited.

The mechanism by which discrete hereditary units, the genes, are reshuffled and passed on to the next generation, the way in which those genes are randomly altered, their molecular nature, and their wonderful ability to encode long chemical messages and replicate those messages precisely—all this was wholly unknown to Darwin. To attempt an understanding of the evolution of life when heredity was still an almost complete mystery would require either an exceptionally foolish or an exceptionally able scientist.

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Josiah Wedgwood and Erasmus Darwin had long entertained the hope that someday their children would formalize through marriage the bonds of affection that already united their two families. Of the two, only Erasmus lived to see it happen. His son, Robert, a generous but moody physician, a great big, fat man, a silhouette out of Dickens, who alternately comforted and terrified the patients of his far-flung practice, married Susannah Wedgwood. She was widely admired for her “gentle, sympathising nature” and the active role she took in her husband’s scientific interests. Susannah suffered an agonizing death from a gastrointestinal affliction out of sight but within earshot of her eight-year-old son, Charles. Writing near the end of his own life, he could recall nothing about his mother “except her death-bed, her black velvet gown, and her curiously constructed work-table.”