Shadows of Forgotten Ancestors

by Carl Sagan

  When we revolve in our minds, first the great changes which we see naturally produced in animals after their nativity as in the production of the butterfly from the crawling caterpillar or of the frog from the subnatant tadpole; secondly when we think over the great changes introduced into various animals by artificial cultivation as in horses or in dogs. .; thirdly when we revolve in our minds the great similarity of structure which obtains in all the warm-blooded animals as well as quadrupeds, birds, amphibious animals as in mankind, would it be too bold to imagine that all warm-blooded animals have arisen from one living filament (archetype, primitive form)?4

  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.

  ——

  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.”

  In this autobiographical memoir, conceived as a gift for his children and grandchildren, and written “as if I were a dead man in another world looking back at my own life,” Charles Darwin admitted “that in many ways I was a naughty boy … I was much given to inventing deliberate falsehoods, and this was always done for the sake of causing excitement.” He boasted to another boy that he “could produce variously coloured polyanthuses and primroses by watering them with certain coloured fluids, which was of course a monstrous fable.” Even at that tender age he had begun to speculate on the variability of plants. His life-long absorption in the natural world was under way. He became a passionate collector of the bits and pieces of Nature that form the gritty detritus in the pockets of children everywhere. He was particularly mad for beetles, but his sister convinced him that it would be immoral to take a beetle’s life merely for collecting. Dutifully, he confined himself to gathering up only the recently deceased. He watched the birds and recorded his observations of their behavior. “In my simplicity,” he later wrote, “I remember wondering why every gentleman did not become an ornithologist.”

  At the age of nine he was sent to study at Dr. Butler’s day school. “Nothing could have been worse for the development of my mind,” Darwin later wrote. Butler believed that school was no place for curiosity or excitement about learning. For that, Charles looked to a well-thumbed copy of Wonders of the World, and to the members of his family who patiently answered his many questions. As an old man he could still recall the delight he felt when an uncle had explained to him how the barometer works. His older brother, Erasmus—named after their grandfather—transformed the garden toolhouse into a chemistry lab and allowed Charles to help him with his experiments. This earned Charles the nickname “Gas” at school and an angry public rebuke from Dr Butler.

  Charles was doing so poorly at school that when it was time for Erasmus to go off to Edinburgh University, his father decided to send Charles with him. The boys were supposed to study medicine. Here, too, Charles found the lectures oppressively dull. He couldn’t bear to dissect anything, and the experience of seeing a botched operation on a child, “long before the blessed days of chloroform,” was to haunt him for the rest of his life. But it was in Edinburgh that he first found friends who shared his passion for science.

  After two sessions at Edinburgh, Robert Darwin became resigned to the fact that Charles was not cut out for a medical career. Perhaps he would make a good clergyman? Dutiful Charles had no objections, but just the same, he thought he should check up on Church of England dogma before agreeing to commit his life to instilling it in others. “Accordingly I read with care Pearson on the Creed, and a few other books on divinity; and as I did not then in the least doubt the strict and literal truth of every word in the Bible, I soon persuaded myself that our Creed must be fully accepted.”

  Charles spent the next three years at Cambridge University, where he managed to get better grades. But still he felt a restless dissatisfaction with the curriculum. His happiest moments there were spent in pursuit of his adored beetles, now dead or alive.

  I will give a proof of my zeal: one day, on tearing off some old bark
, I saw two rare beetles, and seized one in each hand; then I saw a third and new kind, which I could not bear to lose, so that I popped the one which I held in my right hand into my mouth. Alas! it ejected some intensely acrid fluid, which burnt my tongue so that I was forced to spit the beetle out, which was lost, as was the third one.

  It was as a beetle hunter that the first published reference to Charles Darwin was made. “No poet ever felt more delighted at seeing his first poem published than I did at seeing, in Stephen’s Illustrations of British Insects, the magic words, ‘captured by C. Darwin, Esq.’ ”

  At Cambridge he had been persuaded to take a course in geology taught by Adam Sedgwick. Darwin told Professor Sedgwick of the curious but credible claim made to him by a laborer that a “large, worn tropical Volute shell” (the spiral-shaped shell of a warm-water mollusc) had been found embedded in an old Shrewsbury gravel pit. Sedgwick was incurious and dismissive; it must have been dumped there by someone. Darwin remembered in his Autobiography,

  But then, [Sedgwick added,] if [the shell was] really embedded there it would be the greatest misfortune for geology, as it would overthrow all that we know about the superficial deposits of the Midland Counties. These gravel-beds belong in fact to the glacial period, and in after years I found in them broken arctic shells. But I was then utterly astonished at Sedgwick not being delighted at so wonderful a fact as a tropical shell being found near the surface in the middle of England. Nothing before had ever made me thoroughly realise, though I had read various scientific books, that science consists in grouping facts so that general laws or conclusions may be drawn from them.

  At about that time, Darwin’s cousin brought him around to one of the Rev. John Steven Henslow’s botany lectures. This was “a circumstance which influenced my career more than any other.” A handsome man in his early thirties, Henslow had the great teacher’s genius for making his subject come alive, so much so that the same students returned year after year to attend courses they had already completed. Moreover, he exhibited an exceptional sensitivity to the feelings of his students. The novice’s “foolish” question was answered with respect. All were welcome to the open house he held every week, and there were regular invitations to dinner with his family. Darwin wrote, “during the latter half of my time at Cambridge I took long walks with him on most days; so that I was called by some of the dons ‘the man who walks with Henslow.’ ” Darwin judged his knowledge “great in botany, entomology, chemistry, mineralogy, and geology.” He added that Henslow was “deeply religious, and so orthodox that he told me one day he should be grieved if a single word of the Thirty-nine Articles [of the Anglican faith] were altered.”

  Ironically, it was Henslow who left the message “informing me that Captain FitzRoy was willing to give up part of his own cabin to any young man who would volunteer to go with him without pay as naturalist to the Voyage of the Beagle.” Henslow wrote of “a trip to Tierra del Fuego, and home by the East Indies … Two years … I assure you I think you are the very man they are in search of.”

  The scene is not hard to imagine: The twenty-two-year-old races home from college breathless with excitement. He squirms in his chair while Father, an intimidating man in the best of circumstances, harangues him with a litany of past indulgences and harebrained schemes. First, doctor, then, clergyman, now, this? Afterwards, what congregation will want you? They must have first offered it to others and been turned down … Doubtless something is seriously wrong with the vessel … Or the expedition …

  And then, after much discussion: “If you can find any man of common sense, who advises you to go, I will give my consent.”10 The chastened son regards the situation as hopeless and sends Henslow polite regrets.

  The next day he rides over to the Wedgwoods’ for a visit. Uncle Josiah—named after Charles’ grandfather’s boon companion—sees the voyage as a once-in-a-lifetime opportunity. He drops what he’s doing to write Charles’ father a point-by-point refutation of his objections. Later that same day, Josiah worries that a personal appearance might accomplish what a note might not. He grabs Charles and gallops over to the Darwin household to try to convince the young man’s father to let him go. Robert keeps his word and agrees. Touched by his father’s generosity and feeling a little guilty over past extravagances, Charles seeks to reconcile him, saying, “I should be deuced clever to spend more than my allowance whilst on board the Beagle.”

  “But they tell me you are very clever,” his father answers with a smile.

  Robert Darwin had given his blessing, but some obstacles still remained. Captain Robert FitzRoy was having second thoughts about sharing such close quarters for such an extended period of time. A relation of his had known the young Darwin at Cambridge. He said he wasn’t a bad sort, but did FitzRoy, the high Tory, know that he’d be rooming for two years with a Whig? And then there was the pesky problem of Darwin’s nose. FitzRoy was, as were many of his contemporaries, a believer in phrenology, which held that the shape of the skull was indicative of intelligence and character, or their absence. Some adherents expanded this doctrine to include noses. To FitzRoy, Darwin’s nose proclaimed at a glance grave deficiencies in energy and determination. After the two men had spent a little time together, though, FitzRoy, despite his reservations, decided to take a chance on the young naturalist. Darwin wrote, “I think he was afterwards well satisfied that my nose had spoken falsely.”

  The Beagle’s earlier survey mission to South America had been such an unpleasant experience, the weather so consistently rotten, that her Captain had committed suicide before it was over. The British admiralty office in Rio de Janeiro turned to the twenty-three-year-old Robert FitzRoy to assume command. By all accounts he did brilliantly. He was at the helm when the Beagle resumed her survey of Tierra del Fuego and the islands nearby. After the theft of one of the Beagle’s whale boats, FitzRoy kidnapped five of the local people, who were called Fuegians by the British. When he gave up hope of recovering the boat and humanely released his hostages, one of them, a little girl they called Fuegia Basket, didn’t want to leave—or so the story goes. FitzRoy had been wondering about bringing some Fuegians back to England so they might learn its language, mores, and religion. Upon returning home, FitzRoy imagined, they would provide a liaison with other Fuegians and become loyal protectors of British interests at the strategic southern tip of South America. The Lords Commissioners of the Admiralty granted FitzRoy permission to bring the Fuegians to England. Although they were vaccinated, one died of smallpox. Fuegia Basket, a teenaged boy they called Jemmy Button, and a young man they called York Minster survived to study English and Christianity with a clergyman in Wandsworth, and to be presented by FitzRoy to the King and Queen.

  Now it was time for the Fuegians—whose real names no one in England had bothered to learn—to go back; and for the Beagle to resume her survey of South America and “to determine more accurately … the longitude of a large number of oceanic islands as well as of the continents.”11 This assignment was expanded to include “observations of longitude right round the world.” She would sail down the east coast of South America, up the west coast, cross the Pacific, and circumnavigate the planet before returning home to England. Once the Beagle had been re-commissioned under Captain FitzRoy’s command, he took measures to insure that this new expedition would be very different from the previous one. Largely at his own expense, he had the 90-foot square-rigger completely re-fit. He resurfaced her hull, raised her deck, and festooned her bowsprit and her three tall masts with state-of-the-art lightning conductors. He tried to learn everything he could about weather and became one of the founders of modern meteorology in the process. On December 27, 1831, the Beagle was finally ready to sail.

  On the eve of her departure, Darwin had suffered an anxiety attack and heart palpitations. There would be episodes of these symptoms, gastrointestinal distress, and profound bouts of exhaustion and depression throughout his life. Much speculation has been offered on the cause of these spells. They
’ve been attributed to a psychosomatic reaction to the traumatic loss of his mother at so tender an age; to anxieties about the reactions his life’s work might elicit from God and the public; to an unconscious tendency to hyperventilate; and, strangely, although the symptoms pre-date his marriage by many years, to the pleasure he took in his beloved wife’s genius for nursing the sick. The sequence of events also makes implausible the contention that his illness was due to a South American parasite acquired during the Beagle’s voyage. We simply do not know. His symptoms caused this explorer to be mainly housebound for the last third of his life.

  Darwin’s personal library on the journey included two books, each a bon voyage gift. One was an English translation of Humboldt’s Travels that Henslow had given him. Before Darwin left Cambridge he had read Humboldt’s Personal Narrative and Herschel’s Introduction to the Study of Natural Philosophy, which together evoked in Darwin “a burning zeal to add even the most humble contribution to the noble structure of Natural Science.”12 The other gift was from the Captain. It was Volume I of Charles Lyell’s Principles of Geology, and FitzRoy would live to regret bitterly his choice of going-away present.

  The scientific revelations of the European Enlightenment had posed disturbing challenges to the biblical account of the Earth’s origin and history. There were those who tried to reconcile the new data and new insights with their faith. They held that Noah’s flood was the primary agent responsible for the present configuration of the Earth’s crust. A big enough flood, they thought, could transform the Earth’s geology in just forty days and forty nights, consistent with an Earth only a few thousand years old. With a little spin control on a literal reading of the Book of Genesis, they felt they had managed to pull it off.