Though scholars since antiquity had speculated that material objects are made of fundamental building blocks, no one had guessed that so are living things. And so it must have come as quite a surprise when, in 1664, our old friend Robert Hooke sharpened his penknife until it was “as keen as a razor,” shaved a thin slice from a piece of cork, peered at it through his homemade microscope, and became the first human to see what he would call “cells.” He chose that name because they reminded him of the tiny bedrooms assigned to monks in their monasteries.
One can think of cells as the atoms of life, but they are more complex than atoms, and—even more shocking to those who first perceived them—they are themselves alive. A cell is a vibrant living factory that consumes energy and raw materials, and produces from them many diverse products, mainly proteins, which carry out almost every crucial biological function. It takes a lot of knowledge to perform the functions of a cell, so although cells don’t have brains, they do “know” things—they know how to make the proteins and other materials we need to grow and function, and, perhaps most crucial, they know how to reproduce.
The most important single product of a cell is a copy of itself. As a result of that ability, we humans start from a single cell and, through a series of forty-plus cell doublings, we eventually come to be made of about thirty trillion cells—a hundred times more cells than there are stars in the Milky Way. It is a great wonder that the sum of our cells’ activities, the interaction of a galaxy of unthinking individuals, adds up to a whole that is us. Just as staggering a thought is the notion that we could untangle how that all works, like computers that, unbidden by any programmer, analyze themselves. That is the miracle of biology.
The miracle appears even greater when you consider that most of the world of biology is invisible to us. That’s partly due to the minuteness of cells and partly due to the magnificent diversity of life. If you exclude creatures like bacteria and count only living things with cells that have a nucleus, then, scientists estimate, there are roughly ten million species on our planet, of which we have discovered and classified only about 1 percent. There are at least 22,000 species of ants alone, and somewhere between one and ten million individual ants for every person on earth.
We are all familiar with a medley of backyard insects, but a scoop of good soil contains more types of creatures than we could ever count—hundreds or even thousands of invertebrate species, several thousand microscopic roundworms, and tens of thousands of types of bacteria. The presence of life on earth is so pervasive, in fact, that we are continually ingesting organisms that we’d probably rather not eat. Try buying peanut butter that’s free of insect fragments: you can’t. The government recognizes that producing insect-free peanut butter is impractical, so regulations allow for up to ten insect fragments per thirty-one-gram serving. Meanwhile, a serving of broccoli may contain sixty aphids and/or mites, while a jar of ground cinnamon may contain four hundred insect fragments.
That all sounds unappetizing, but it’s good to remember that even our own bodies are not free of foreign life—we are, each of us, an entire ecosystem of living things. Scientists have identified, for example, forty-four genera (species groups) of microscopic organisms that live on your forearm, and at least 160 species of bacteria that live in people’s bowels. Between your toes? Forty species of fungi. In fact, if you bother to total it up, you find that there are far more microbial cells in our bodies than human cells.
Our body parts each form a distinct habitat, and the creatures in your intestines or between your toes have more in common with the organisms in those regions of my body than with the creatures on your own forearm. There is even an academic center called the Belly Button Biodiversity project at North Carolina State University, set up to study the life that exists in that dark, isolated landscape. And then there are the infamous skin mites. Relatives of ticks, spiders, and scorpions, these creatures are less than a third of a millimeter long and live on your face—in hair follicles and glands connected to hair follicles—mainly near the nose, eyelashes, and eyebrows, where they suck the innards out of your juicy cells. But don’t worry, they normally cause no ill effects, and if you’re an optimist, you can hope you’re among the half of the adult population that is free of them.
Given the complexity of life, its diversity in size, shape, and habitat, and our natural disinclination to believe that we are “mere” products of physical law, it is not surprising that biology lagged behind physics and chemistry in its development as a science. Like those other sciences, for biology to grow it had to overcome the natural human tendencies to feel that we are special and that deities and/or magic govern the world. And, as in those other sciences, that meant overcoming the God-centric doctrine of the Catholic Church and the human-centric theories of Aristotle.
Aristotle was an enthusiastic biologist—almost a quarter of his surviving writings pertain to that discipline. And while Aristotle’s physics has our earth at the physical center of the universe, his biology, more personal, exalts humans, and males in particular.
Aristotle believed that a divine intelligence designed all living beings, which differ from the inanimate in that they have a special quality or essence that departs or ceases to exist when the living thing dies. Among all those blueprints for life, Aristotle argued, humans represent the high point. On this point Aristotle was so vehement that when he described a characteristic of a species that differs from the corresponding human characteristic, he referred to it as a deformity. Similarly, he viewed the human female as a deformed or damaged male.
The erosion of such traditional but false beliefs set the stage for the birth of modern biology. One of the important early victories over such ideas was the debunking of a principle of Aristotle’s biology called spontaneous generation, in which living things were said to arise from inanimate matter such as dust. Around the same time, by showing that even simple life has organs as we do, and that we, like other plants and animals, are made of cells, the new technology of the microscope cast doubt on the old ways of thinking. But biology could not begin to really mature as a science until the discovery of its great organizing principle.
Physics, which concerns how objects interact, has its laws of motion; chemistry, which concerns how elements and their compounds interact, has its periodic table. Biology concerns itself with the ways in which species function and interact, and to succeed, it needed to understand why those species have the characteristics they do—an explanation other than “Because God made them that way.” That understanding finally came with Darwin’s theory of evolution based on natural selection.
Long before there was biology, there were observers of life. Farmers, fishermen, doctors, and philosophers all learned about the organisms of the sea and the countryside. But biology is more than what is detailed in catalogs of plants or field guides to the birds, for science doesn’t just sit quietly and describe the world; it jumps up and screams ideas that explain what we see. To explain, though, is much more difficult than to describe. As a result, before the development of the scientific method, biology, like the other sciences, was plagued by explanations and ideas that were reasonable—but wrong.
Consider the frogs of ancient Egypt. Each spring, after the Nile inundated the surrounding lands, it left behind nutrient-rich mud, the kind of land that, through the farmers’ diligent toil, would soon feed the nation. The muddy soil also yielded another crop that did not exist on drier land: frogs. The noisy creatures appeared so suddenly, and in numbers so vast, that they seemed to have arisen from the mud itself—which is precisely how the ancient Egyptians believed they came into being.
The Egyptian theory was not the product of flabby reasoning. Assiduous observers through most of history have reached the same conclusion. Butchers noted that maggots “appeared” on meat, farmers found mice “appearing” in bins in which wheat was stored. In the seventeenth century, a chemist named Jan Baptist van Helmont even went so far as to recommend a recipe to create mice from everyday materials: just put a few grains of wheat in a pot, add dirty underwear, and wait twenty-one days. The recipe reportedly often worked.
The theory behind van Helmont’s concoction was spontaneous generation—that simple living organisms can arise spontaneously from certain inanimate substrates. Ever since the time of ancient Egypt, and probably before, people believed that some sort of life force or energy exists in all living creatures. Over time, a by-product of such views was the conviction that life energy could somehow become infused into inanimate matter, creating new life, and when that doctrine was synthesized into a coherent theory by Aristotle, it gained special authority. But just as certain key observations and experiments in the seventeenth century represented the beginning of the end of Aristotle’s physics, so too did the rise of science in that century finally bring his ideas about biology under potent attack. Among the most memorable challenges was a test of spontaneous generation performed by Italian physician Francesco Redi in 1668. It was one of biology’s first truly scientific experiments.
Redi’s method was simple. He procured some widemouthed jars and placed in them samples of fresh snake meat, fish, and veal. Then he left some of the jars uncovered while covering others with a gauzelike material or paper. He hypothesized that if spontaneous generation really occurred, flies and maggots should appear on the meat in all three situations. But if maggots arose instead, as Redi suspected, from tiny invisible eggs laid by flies, they should appear on the meat in the uncovered jars but not in the jars covered by paper. He also predicted that maggots would appear on the gauze covering in the remaining jars, which was as close to the meat as the hungry flies could get. That was exactly what occurred.
Redi’s experiment met with a mixed reception. To some, it appeared to debunk spontaneous generation. Others chose to ignore it, or to find fault. Many probably fell in the latter category simply because they were biased toward maintaining their prior beliefs. After all, the issue had theological implications—some felt that spontaneous generation preserved a role for God in creating life. But there were also scientific reasons for doubting Redi’s conclusion—for example, it could be wrong to extrapolate the validity of his experiment beyond the creature he’d studied. Perhaps all he had demonstrated was that spontaneous generation does not apply to flies.
To his credit, Redi himself kept an open mind—he even found other cases where he suspected that spontaneous generation did occur. Ultimately, the issue would be argued about for another two hundred years, until Louis Pasteur, in the late nineteenth century, put it to rest for good with his careful experiments showing that not even microorganisms are generated spontaneously. Still, though not definitive, Redi’s work was gorgeous. It stands out especially because anyone could have carried out a similar test, and yet no one thought to.
People often think of great scientists as having extraordinary intelligence, and in society, and especially in business, we tend to shun people who don’t blend well with others. But it is those who are different who often see what others do not. Redi was a complex man—a scientist but also a man of superstition who greased himself with oil to ward off disease, a physician and naturalist but also a poet who wrote a classic in praise of Tuscan wines. With regard to spontaneous generation, only Redi was odd enough to think outside the box, and in an age before scientific reasoning was commonplace, he reasoned and acted as scientists do. In doing so, he not only cast doubt on an invalid theory, but he poked a stick at Aristotle, and pointed conspicuously to a new approach to answering the questions of biology.
Redi’s experiment was in great part a reaction to microscope studies that had recently revealed that minute creatures are complex enough to have reproductive organs—for the belief that “lower animals” are too simple to reproduce was one of Aristotle’s arguments for spontaneous generation.
The microscope had actually been invented decades earlier—around the time of the telescope—though no one knows for certain exactly when, or by whom. We do know that at first the same Latin word, perspicillum, was employed for both, and Galileo even used the same instrument—his telescope—to gaze both inward and outward. “With this tube,” he told a visitor in 1609, “I have seen flies which look as big as lambs.”
By revealing the details of a realm of nature that could never have been imagined by the ancients—or accounted for in theories—the microscope, like the telescope, eventually helped to open scholars’ minds to different ways of thinking about their subject, creating a thread of intellectual progress that would reach a high point with Darwin. But, like the telescope, the microscope also initially met with strong opposition. Medieval scholars were wary of “optical illusions” and distrusted any device that stood between them and the objects they perceived. And while the telescope had its Galileo, who quickly stood up to the critics and adopted the device, it took half a century for the champions of the microscope to make their mark.
One of the greatest champions was Robert Hooke, who did his microscopic studies at the behest of the Royal Society, and thus contributed to the roots of biology, just as he had contributed to chemistry and physics. In 1663, the Royal Society assigned Hooke the task of presenting at least one novel observation at each meeting. Despite an eye infirmity that made it both difficult and painful to stare into a lens for a long time, he lived up to the challenge and made a long series of extraordinary observations employing improved instruments that he himself had designed.
In 1665, the thirty-year-old Hooke published a book titled Micrographia, or “Small Drawings.” It was a bit of a hodgepodge of Hooke’s work and ideas in several fields, but it made a splash by revealing a strange new microworld through fifty-seven amazing illustrations that Hooke himself drew. They exposed to human perception for the first time the anatomy of a flea, the body of a louse, the eye of a fly, and the stinger of a bee, all blown up to full-page images, some even presented as foldouts. That even simple animals have body parts and organs as we do was not just a striking revelation to a world that had never seen an insect magnified; it was also a direct contradiction of Aristotelian doctrine, a revelation similar to Galileo’s discovery that the moon has hills and valleys just like the earth does.
The year Micrographia was published was the year the Great Plague, which would kill one in seven Londoners, reached its summit. The next year, London was engulfed by the Great Fire. But despite all that chaos and suffering, people read Hooke’s book, and it became a best seller. So engrossed was Samuel Pepys, the famous diarist and naval administrator and later a member of Parliament, that he sat up until two in the morning devouring it, then called it “the most ingenious book that ever I read in my whole life.”
Though Hooke excited a new generation of scholars, he also drew the ridicule of doubters who found it difficult to accept his sometimes grotesque portrayals, based on observations employing an instrument they did not trust. The low point came when, attending a satire of contemporary science written by English playwright Thomas Shadwell, Hooke was humiliated upon realizing that the experiments being mocked on the stage before him were mostly his own. They had been drawn from his beloved book.
Hooke’s Micrographia
One man who didn’t doubt Hooke’s claims was an amateur scientist named Anton van Leeuwenhoek (1632–1723). He was born in Delft, Holland. His father made baskets in which the famous blue-and-white Delft pottery was packaged for shipment around the world; his mother came from a family engaged in another Delft specialty—brewing beer. At age sixteen, young Anton took a job as cashier and bookkeeper for a cloth merchant, and in 1654 he opened his own business, selling fabric, ribbons, and buttons. To that he would soon add another, unrelated, occupation: seeing to the maintenance and upkeep of Delft’s town hall.
Leeuwenhoek never attended college and did not know Latin—then the language of science. And though he would live past ninety, he left the Netherlands just twice—once to visit Antwerp, in Belgium, and once to go to England. But Leeuwenhoek did read books, and one that inspired him was Hooke’s best seller. The book changed his life.
In its preface, Micrographia explains how to build simple microscopes, and as a fabric merchant, Leeuwenhoek probably had some experience grinding lenses, for he would have needed them to examine samples of linen. But after reading Micrographia, he became a fanatical lens maker, devoting hour after hour to creating new microscopes and making observations employing them.
In his early work, Leeuwenhoek simply repeated Hooke’s experiments, but he soon eclipsed them. Hooke’s microscopes were, for their time, technologically superior, and he had wowed the Royal Society with his magnifications of twenty to fifty power. So one can only imagine the astonishment when, in 1673, the secretary of the Society, Henry Oldenburg, received a letter informing him that an uneducated custodian and fabric purveyor in the Netherlands had “devised microscopes which far surpass those which we have hitherto seen.” In fact, the forty-one-year-old Leeuwenhoek was reaching magnifications ten times those achieved by Hooke.
It was superior craftsmanship rather than clever design that made Leeuwenhoek’s microscopes so powerful. They were in fact simple devices, made from just a single lens ground from select fragments of glass, or even grains of sand, and mounted on plates made from gold and silver that he sometimes extracted from the ore himself. He fixed each specimen permanently and made a new microscope for every study, perhaps because achieving the proper positioning was as difficult as creating the lens. Whatever the reason, he didn’t share it with anyone and was generally very secretive about his methods, because, like Newton, he wanted to avoid “contradiction or censure from others.” Over his long life, he produced more than five hundred lenses, but to this day no one knows exactly how he created them.
When word of Leeuwenhoek’s achievements arrived, the English and Dutch navies were firing cannons at each other in the Anglo-Dutch Wars, but being at war with Leeuwenhoek’s country didn’t stop Oldenburg: he encouraged Leeuwenhoek to report his findings, and the Dutchman did. In his first letter, Leeuwenhoek, intimidated by the attention of the famous Royal Society, apologized if they noted shortcomings in his work. It was, he wrote, “the outcome of my own unaided impulse and curiosity alone; for beside myself in our town there are no philosophers who practice this art; so pray take not amiss my poor pen and the liberty I have taken in setting down my random notions.”
Leeuwenhouk’s “notions” were an even greater revelation than Hooke’s. For where Hooke had seen in detail the body parts of tiny insects, Leeuwenhoek saw entire creatures that were too small to see with the naked eye, complete societies of organisms whose existence no one had previously suspected, some a thousand or even ten thousand times tinier than the smallest animal visible to the naked eye. He called them “animalcules.” Today we call them microorganisms.
If Galileo reveled in viewing the landscape of the moon and spying the rings of Saturn, Leeuwenhoek took equal delight in observing through his lenses new worlds of bizarre and minute creatures. In one letter, he wrote of the world that existed in a drop of water: “I now saw very plainly that these were little eels, or worms, lying all huddled up together and wriggling … the whole water seemed to be alive with these multifarious animalcules … I must say, for my part, that no more pleasant sight has ever come before my eye than these thousands of living creatures, seen all alive in a little drop of water.”
But if Leeuwenhoek sometimes reported a God’s-eye overview of entire worlds, in other reports he told of magnifying individual creatures enough to describe many new species in great detail. For example, he described one creature as having “stuck out two little horns which were continually moved, after the fashion of a horse’s ears … [with a roundish body], save only that it ran somewhat to a point at the hind end; at which pointed end it had a tail.” Over a period of fifty years, Leeuwenhoek never attended a meeting of the Royal Society, but he wrote it hundreds of letters, and the majority have been preserved. Oldenburg had them edited and translated into English or Latin, and the Royal Society published them.
Leeuwenhoek’s work created a sensation. The world was stunned to learn that there were whole universes of creatures in every drop of pond water, and entire classes of life entirely hidden from our senses. What’s more, when Leeuwenhoek turned his microscopes upon human tissue such as sperm cells and blood capillaries, he helped to reveal our own construction, and how it is unexceptional, in that we have much in common with other life forms.
Like Hooke, Leeuwenhoek had doubters who believed he was making everything up. He countered them by providing signed testimonials from respected eyewitnesses, notaries public, and even the pastor of the congregation in Delft. The majority of scientists believed him, and Hooke was even able to reproduce some of Leeuwenhoek’s research. As the word spread, visitors from everywhere showed up at Leeuwenhoek’s shop, asking to gaze at his tiny beasts. Charles II, the founder and patron of the Royal Society, asked Hooke for a showing of one of the Leeuwenhoek experiments he had replicated, and Peter the Great of Russia visited Leeuwenhoek himself. Not bad for a guy who ran a fabric store.
In 1680, Leeuwenhoek was elected, in absentia, a fellow of the Royal Society, and he kept working till his end, at age ninety-one, some forty years later. No comparable microbe hunter would come onto the scene for another 150 years.
As Leeuwenhoek lay dying, the last thing he did was ask a friend to translate his final two letters into Latin and send them to the Society. He had also prepared them a gift: a black-and-gilt cabinet filled with his best microscopes, some of which he had never before shown anyone. Today, only a handful of his microscopes remain intact; in 2009, one sold at auction for 312,000 pounds.
In his long life, Leeuwenhoek helped establish many aspects of what would become biology—microbiology, embryology, entomology, histology—causing one twentieth-century biologist to call Leeuwenhouk’s letters the “most important series of communications that a scientific society has ever received.” Just as important—like Galileo in physics and Lavoisier in chemistry—Leeuwenhoek helped to establish a scientific tradition in the field of biology. As the pastor of the New Church at Delft wrote to the Royal Society on Leeuwenhoek’s death, in 1723, “Anton van Leeuwenhoek considered that what is true in natural philosophy can be most fruitfully investigated by the experimental method, supported by the evidence of the senses; for which reason, by diligence and tireless labor he made with his own hand certain most excellent lenses, with the aid of which he discovered many secrets of Nature, now famous throughout the whole philosophical World.”
If Hooke and Leeuwenhoek were in a sense the Galileos of biology, its Newton was Charles Darwin (1809–1882). Fittingly, he is buried just a few feet away from Newton in Westminster Abbey, his pallbearers having included two dukes and an earl as well as past, present, and future presidents of the Royal Society. Though Darwin’s burial in an abbey may seem incongruous to some, “it would have been unfortunate,” said the Bishop of Carlisle in his memorial sermon, “if anything had occurred to give weight and currency to the foolish notion … that there is a necessary conflict between a knowledge of Nature and a belief in God.” The interment was a glorious end for a man whose principal scientific achievement was met, at first, with little more than a yawn, and then with much venom and skepticism.
One of those initially underwhelmed was Darwin’s own publisher, John Murray, who had agreed to release the book in which Darwin elaborated on his theory but gave it an initial press run of just 1,250 copies. Murray had good reason to worry, for those who had seen Darwin’s book in advance were unenthusiastic. One early reviewer even recommended that Murray not publish it at all—it was “an imperfect and comparatively meager exposition of his theory,” he wrote. And then the reviewer suggested that Darwin write a book on pigeons instead, and include in that book a brief statement of his theory. “Everybody is interested in pigeons,” the reviewer advised. “The book would … soon be on every table.” The advice was passed on to Darwin, but he declined it. Not that he himself was confident that his book would sell. “God knows what the public will think,” he remarked.
Darwin need not have worried. On the Origin of Species by Means of Natural Selection; or, the Preservation of Favoured Races in the Struggle for Life would become biology’s Principia. Published on November 24, 1859, all 1,250 copies were immediately snatched up by eager booksellers, and it has been in print ever since. (The book did not, however, sell out on its publication day, as legend has it.) It was gratifying validation for the man who had had the passion and patience to spend twenty years accumulating evidence for his ideas—an effort so monumental that just one of its many by-products was a 684-page monograph on barnacles.
Darwin’s predecessors had learned many descriptive details about life forms from bacteria to mammals, but they hadn’t had a clue about the more fundamental question of what drove species to have the characteristics they possess. Like physicists before Newton or chemists before the periodic table, pre-Darwinian biologists gathered data but didn’t know how it fit together. They couldn’t, for before Darwin the young field of biology was shackled by the conviction that the origins and interrelationships of different forms of life were beyond science—a conviction that arose from the literal acceptance of the biblical story of creation, which held that the earth and all life forms were created in six days and that, in the time since, species had not changed.
It’s not that there hadn’t been thinkers who’d pondered the idea that species evolve—there were, going back to the Greeks, and these included Darwin’s own grandfather, Erasmus Darwin. But pre-Darwinian evolution theories were vague and not much more scientific than the religious doctrine they would be replacing. As a result, though there was talk of the idea of evolution before Darwin, most people, including scientists, accepted that humans rested atop a pyramid of more primitive species whose characteristics were fixed and had been designed by a creator to whose thinking we could never be privy.
Darwin changed that. If before him there existed a grove of speculations about evolution, his theory towered over the other trees, a majestic specimen of careful science. For every argument or piece of evidence his precursors supplied, he offered a hundred. More important, he discovered the mechanism behind evolution—natural selection—and thus made evolution theory testable, and scientifically respectable, freeing biology from its reliance on God and allowing it to become a true science, one rooted, like physics and chemistry, in physical law.
Born at his family’s home in Shrewsbury, England, on February 12, 1809, Charles was the son of Robert Darwin, the town physician, and Susannah Wedgwood, whose father had founded the pottery firm of that name. The Darwins were a well-to-do and illustrious family, but Charles was a poor student who hated school. He would later write that he had a bad memory for rote learning and “no special talents.” He was selling himself short, for he also recognized that he had a “great curiosity about facts, and their meaning,” and “energy of mind shown by vigorous and long-continued work on the same subject.” These latter two traits are, for a scientist—or any innovator—indeed special talents, and they would serve Darwin well.
Darwin’s curiosity and determination are well illustrated by an incident that occurred when he was in college at Cambridge, obsessed with a hobby of collecting beetles. “One day,” he wrote, “on tearing off some old bark, I saw two rare beetles & seized one in each hand; then I saw a third & new kind, which I could not bear to lose, so I popped the one which I held in my right hand into my mouth.” Only from a boy of that character can emerge a man with the tenacity to put together 684 pages on the topic of barnacles (though before he was finished he would write, “I hate a barnacle as no man ever did before”).
It took many years for Charles to find his calling. His journey began in the fall of 1825 when his father sent him, at age sixteen, not to Cambridge but to the University of Edinburgh—to study medicine, as both he and Charles’s grandfather had done. It proved to be a bad decision.
For one, Charles was famously squeamish, and this was an era in which operations featured copious splashes of blood and screaming patients, cut into without the benefit of anesthetic. Still, squeamishness wouldn’t stop Charles, years later, from dissecting dogs and ducks as he searched for evidence supporting his theory of evolution. Probably what proved fatal to his medical studies was the lack of both interest and motivation. As he would later write, he had become convinced that his father would leave him enough property “to subsist on with some comfort,” and this expectation was “sufficient to check any strenuous effort to learn medicine.” And so, in the spring of 1827, Charles left Edinburgh without a degree.
Cambridge was his second stop. His father sent him there with the idea that he should study divinity and then embark upon a clerical career. This time Charles completed his degree, ranking tenth out of 178 graduates. His high ranking surprised him, but it reflected, perhaps, that he had developed a genuine interest in geology and natural history—as evidenced by his beetle collecting. Still, he seemed headed for a life in which science would be at best a hobby, while his professional energies would be devoted to the church. But then, on returning home from a postgraduation geological walking tour of North Wales, Darwin found a letter that presented a different option: the chance to sail around the world on the HMS Beagle, under one Captain Robert Fitzroy.
The letter was from John Henslow, a Cambridge professor of botany. Despite his high ranking, Darwin hadn’t stood out to many at Cambridge; Henslow, however, had seen potential in him. He once remarked, “What a fellow that Darwin is for asking questions”—a seemingly bland compliment, but it says that in Henslow’s mind, Darwin had the soul of a scientist. Henslow befriended the curious student, and when he was asked to recommend a young man for the position of naturalist on the voyage, he recommended Darwin.
Henslow’s letter to Darwin was the culmination of a series of unlikely events. It all began when the Beagle’s previous captain, Pringle Stokes, shot himself in the head and, after the bullet didn’t kill him, died of gangrene. Fitzroy, Stokes’s first lieutenant, brought the ship home, but it wasn’t lost on him that Stokes’s depression had been spurred by the loneliness of a multiyear sea voyage in which the captain was forbidden to socialize with his crew. Fitzroy’s own uncle had slit his throat with a razor a few years earlier, and some four decades later Fitzroy himself would follow suit, so he must have sensed that his captain’s fate was one he should do his best to avoid. As a result, when the twenty-six-year-old Fitzroy was offered the opportunity to succeed Stokes, he decided he needed a companion. It was the custom at the time for the ship’s doctor to double as its naturalist, but Fitzroy instead put word out that he sought a young “gentleman-naturalist” of high social standing—a person to serve, essentially, as his hired friend.
Darwin was not Fitzroy’s first choice for the position—it had previously been offered to a number of others. Had any of them accepted it, Darwin most likely would have proceeded to his quiet life in the church and never created his theory of evolution—just as Newton would probably never have completed and published his great work had Halley not stopped to see him and ask about the inverse square law. But the position Fitzroy was offering paid nothing—the compensation was to come from the later sale of specimens collected on shore visits along the way—and none of those asked were willing or able to spend years at sea, self-financed. As a result, the choice finally fell to the twenty-two-year-old Darwin, offering him a chance at adventure—and to avoid starting a career in which he’d preach that the earth had been created on the night preceding October 23, 4004 B.C. (as claimed in a biblical analysis published in the seventeenth century). Darwin seized the opportunity. It would change both his life and the history of science.
The Beagle set off in 1831 and wouldn’t return until 1836. It was not a comfortable trip. Darwin resided and worked in the ship’s tiny poop cabin, in the roughest-riding section of the ship. He shared the room with two others and slept in a hammock slung over the chart table. “I have just room to turn round & that is all,” he reported in a letter to Henslow. Not surprisingly, he was racked by seasickness. And though Darwin forged a friendship of sorts with Fitzroy—he was the only member of the ship to have any intimacy with the captain, and they usually dined together—they quarreled often, especially over slavery, which Darwin despised but which they observed repeatedly in their time ashore.
Still, the discomforts of the voyage were offset by the unparalleled excitement of the shore visits. During those periods, Darwin participated in the Carnival in Brazil, watched a volcano erupt outside Osorno, Chile, experienced an earthquake and walked through the ruins it left in Concepción, and observed revolutions in Montevideo and Lima. All the while, he collected specimens and fossils, packaged them, and shipped them in crates back to Henslow in England for storage.
Darwin would later consider the voyage to have been the main formative event of his life, both for the impressions it left on his character and for the new appreciation it gave him of the natural world. It was not during the voyage, however, that Darwin made his famous discoveries regarding evolution, or even grew to accept that evolution occurred. He in fact ended the voyage as he had begun it—with no doubts regarding the moral authority of the Bible.
Yet his plans for the future did change. As the voyage ended, he wrote to a cousin who’d made a career in the church, “Your situation is above envy; I do not venture to even frame such happy visions. To a person fit to take the office, the life of a Clergyman is … respectable & happy.” Despite those encouraging words, Darwin had decided that he himself was not suited to that life, and he chose instead to make his way in the world of London science.
Back in England, Darwin found out that the observations he had detailed in casual letters to Professor Henslow had received some scientific notice—in particular, those regarding geology. Soon Darwin was lecturing at the prestigious Geological Society of London on topics like “the Connexion of Certain Volcanic Phenomena and the Formation of Mountain-Chains and the Effects of Continental Elevations.” Meanwhile, he enjoyed financial independence thanks to a stipend of four hundred pounds per year from his father. Coincidentally, it was the same amount Newton had earned when he began at the mint, but in the 1830s, according to the British National Archives, it was “only” five times the wage of a craftsman (though still enough to buy twenty-six horses or seventy-five cows). The money allowed Darwin to devote time to turning his Beagle diary into a book, and to sorting through the many animal and plant specimens he’d collected. It was this effort that would change our ideas about the nature of life.
Since Darwin hadn’t had any great epiphanies about biology during his voyage, he probably expected the scrutiny of the specimens he’d sent home to result in a solid but not revolutionary body of work. There were soon signs, however, that his investigations might be more exciting than expected—he had given some of his specimens to specialists to analyze, and many of their reports astonished him.
One group of fossils, for example, suggested “a law of succession”—that extinct South American mammals had been replaced by others of their kind. Another report, on the mockingbirds of the Galápagos Islands, informed him that there were three species, not the four he had believed, and that they were island specific, as were the giant tortoises found there. (The story about his being inspired to a eureka moment by observing differences in the beaks of the finches on different islands of the Galápagos is apocryphal. He did bring back finch specimens, but he hadn’t been trained in ornithology and had actually misidentified them as a mix of finches, wrens, “Gross-beaks,” and blackbird relatives—and they were not labeled by island.)
Perhaps the most striking of the experts’ reports concerned a specimen of rhea, or South American ostrich, that Darwin and his team had cooked and eaten before realizing its possible significance and shipping its remains home. That specimen turned out to belong to a new species, which, like the common rhea, had its own principal range but which also competed with the common rhea in an intermediate zone. This contradicted the conventional wisdom of the time, which held that every species is optimized for its particular habitat, leaving no room for ambiguous regions in which similar species compete.
As these provocative studies were coming in, Darwin’s own thoughts on the role of God in creation were evolving. One major influence was Charles Babbage, who held Newton’s former position as Lucasian professor of mathematics at Cambridge, and is best known for inventing the mechanical computer. Babbage hosted a series of soirees attended by freethinkers and was himself writing a book proposing that God worked through physical laws, not fiat and miracle. That idea, which provided the most promising basis for the coexistence of religion and science, appealed to the young Darwin.
Gradually, Darwin became convinced that species were not unchanging life forms designed by God to fit into some grand scheme, but rather had somehow adapted themselves to fit into their ecological niche. By the summer of 1837—the year after the Beagle ended her voyage—Darwin had become a convert to the idea of evolution, though he was still far from formulating his particular theory of it.
Soon Darwin was rejecting the notion that humans are superior, or indeed that any animal is superior to another, and in its place he now held the conviction that each species is equally marvelous, a perfect or nearly perfect fit for its environment and its role within it. None of this, to Darwin, precluded God from playing a hands-on role: he believed that God had designed the laws governing reproduction to allow species to alter themselves as needed to adapt to environmental change.
If God created laws of reproduction that enabled species to become tailored to their environment, what are those laws? Newton understood God’s plan for the physical universe through his mathematical laws of motion; so, too, did Darwin—at least initially—seek the mechanism of evolution, thinking it would explain God’s plan for the living world.
Like Newton, Darwin began to fill a series of notebooks with his thoughts and ideas. He analyzed the relationships among the species and fossils he had observed in his travels; he studied an ape, an orangutan, and monkeys in the London Zoo, taking notes on their humanlike emotions; he examined the work of pigeon, dog, and horse breeders and pondered how great a variation in traits could be produced through their method of “artificial selection”; and he speculated in a grand manner regarding how evolution had an impact on metaphysical questions and human psychology. And then, around the month of September 1838, Darwin read T. R. Malthus’s popular Essay on the Principle of Population. It put him on the path to finally discovering the process through which evolution occurred.
Malthus had not written a pleasant book. Misery, in his view, was the natural and eventual state of humankind, because population increases invariably lead to violent competition for food and other resources. Due to limits on land and production, he argued, those resources can only increase “arithmetically,” as in the series 1, 2, 3, 4, 5, and so on, while population increases each generation according to the series 1, 2, 4, 8, 16, and so on.
Today we know that a single squid can produce three thousand eggs in one season. If each egg grew into a squid and reproduced, by the seventh generation the volume of squid would fill a hollowed-out earth; in fewer than thirty generations, the eggs alone would fill the observable universe.
Darwin didn’t have that particular data, and he wasn’t good at math, but he knew enough to realize that the Malthusian scenario doesn’t happen. Instead, he reasoned, of the prodigious number of eggs and offspring nature produces, competition leaves only a few—on average, those best adapted—to survive. He called the process “natural selection,” to emphasize the comparison with the artificial selection exercised by breeders.
Later, in his autobiography, Darwin described having an epiphany: “It at once struck me that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed.” But new ideas rarely jump into the discoverer’s mind that suddenly, or neatly formed, and Darwin’s description seems to have been a distortion of happy hindsight. Examinations of the notebooks he was keeping at the time reveal a different story: at first he only sniffed the trace of an idea, and it would be several years before he perceived it clearly enough to set it down on paper.
One reason the idea of natural selection took some time to develop is that Darwin recognized that weeding out the unfit in every generation may hone a species’s traits, but it will not create new species—individuals that are so dissimilar from the original species that they can no longer interbreed and produce fertile offspring. For that to happen, the culling of existing traits must be complemented by a source of new traits. That, Darwin eventually concluded, arises from pure chance.
Bill color in zebra finches, for example, normally varies from paler to stronger red. Through careful breeding, one might be able to create populations favoring one or the other, but a zebra finch with a new beak color—say, blue—can occur only through what we now call a mutation: a chance alteration in the structure of a gene that results in a novel, variant form of the organism.
Now Darwin’s theory could finally jell. Together, random variation and natural selection create individuals with new traits, and give those traits that are advantageous an increased chance of being propagated. The result is that, just as breeders produce animals and plants with the traits they desire, so, too, does nature create species that are well adapted to their environment.
The realization that randomness plays a role represented an important milestone in the development of science, for the mechanism Darwin had discovered made it difficult to reconcile evolution with any substantive idea of divine design. Of course, the concept of evolution in itself contradicts the biblical story of creation, but Darwin’s particular theory now went further, making it difficult to rationalize the Aristotelian and traditional Christian views that the unfolding of events is driven by purpose rather than indifferent physical law. In that respect, Darwin did for our understanding of the living world what Galileo and Newton had done for the inanimate: he divorced science from its roots in both religious questioning and the ancient Greek traditions.
Darwin, like Galileo and Newton, was a man of religious faith, so his evolving theory presented him with contradictions in his belief system. He tried to avoid the clash by accepting both the theological and scientific views, each in their own context, rather than actively attempting to reconcile them. Yet he couldn’t avoid the issue entirely, for in January 1839 he married his first cousin, Emma Wedgwood, a devout Christian who was disturbed by his views. “When I am dead,” he once wrote her, “know that many times I have … cryed over this.” Despite their differences, their bond was a strong one, and they remained throughout their lives a devoted couple, producing ten children.
Annie Darwin (1841–1851)
Though much has been written regarding the question of reconciling evolution with Christianity, it was the death, years later, of the Darwins’ second child, Annie, at age ten, that, as much as his work on evolution, finally destroyed Darwin’s faith in Christianity. The cause of Annie’s death is unclear, but she suffered at the end for more than a week, with high fever and severe digestive issues. Afterward Darwin wrote, “We have lost the joy of the Household, and the solace of our old age:—she must have known how we loved her; oh that she could now know how deeply, how tenderly we do still & shall ever love her dear joyous face.”
The couple’s first child had come in 1839. By then Darwin, just thirty, had begun to suffer debilitating bouts of a (to this day) mysterious illness. For the rest of his life, the joy he experienced from his family and scientific work would be punctuated by frequent eruptions of painful disability that at times left him unable to work for months on end.
Darwin’s symptoms pointed everywhere, like the plagues in the Bible: stomach pain, vomiting, flatulence, headaches, heart palpitations, shivering, hysterical crying, tinnitus, exhaustion, anxiety, and depression. The attempted cures, some of which the desperate Darwin signed on for against his better judgment, were equally diverse: vigorous rubbing with cold wet towels, footbaths, ice rubs, freezing-cold showers, faddish electrotherapy employing shocking belts, homeopathic medicines, and that Victorian standard, bismuth. Nothing worked. And so the man who at twenty was a rugged adventurer had become, by age thirty, a frail and reclusive invalid.
With the new child, his work, and the illness, the Darwins began to withdraw, giving up parties and their old circles. Darwin’s days became quiet and routine, as alike “as two peas.” In June 1842, Darwin finally completed a thirty-five-page synopsis of his evolution theory; that September, he persuaded his father to lend him the money to buy a fifteen-acre retreat in Down, Kent, a parish of about four hundred inhabitants, sixteen miles from London. Darwin referred to it as “the extreme verge of the world.” His life there was like that of the prosperous country parson he had once intended to be, and by February 1844 he had used his quiet time to expand the work into a 231-page manuscript.
Darwin’s manuscript was a scientific will, not a work intended for immediate publication. He entrusted it to Emma with a letter that she was to read it in the event of his “sudden-death,” which, due to his illness, he feared might be imminent. The letter instructed her that it was his “most solemn and last request” that after his demise the manuscript be made public. “If it be accepted even by one competent judge,” Darwin wrote, “it will be a considerable step in science.”
Darwin had good reason not to want his views published in his lifetime. He had earned a stellar reputation in the highest circles of scientific society, but his new ideas were bound to attract criticism. What’s more, he had many clerical friends—not to mention a wife—who supported the creationist status quo.
Darwin’s reasons for hesitation seemed to be validated in the fall of that year, when a book called Vestiges of the Natural History of Creation appeared, published anonymously.* The book did not present a valid theory of evolution, but it did weave together several scientific ideas, including the transmutation of species, and it became an international best seller. The religious establishment, however, railed against its unknown author. One reviewer, for example, accused him of “poisoning the foundations of science, and sapping the foundations of religion.”
Some in the scientific community were not much kinder. Scientists have always been a tough crowd. Even today, with easy communication and travel enabling more cooperation and collaboration than ever before, presenting new ideas can open you to rude attack, for, along with a passion for their subject and their ideas, scientists sometimes also exhibit fervor in opposing work they deem misguided, or simply uninteresting. If the talk being given by a visitor describing his work at a research seminar did not prove worthy of his attention, one famous physicist I knew would pull out a newspaper, open it wide, and start reading, displaying conspicuous boredom. Another, who liked to sit near the front of the room, would stand in the midst of the talk, announce his negative opinion, and walk out. But the most interesting display I’ve seen came from yet another well-known scientist, a fellow familiar to generations of physicists because he’d written the standard graduate text on electromagnetism.
Sitting up front in a seminar room in which the rows of chairs were only about a dozen deep, this professor raised his Styrofoam coffee cup high over his head and rotated it back and forth slightly so that all those behind him—but not the puzzled speaker in front of him—could see that he had written on it, in large block letters, the message THIS TALK IS BULLSH-T! And then, having made his contribution to the discourse, he got up and walked out. Ironically, the talk was on the topic of “The Spectroscopy of Charm-Anticharm Particles.” Though the word “charm” here is a technical term unrelated to its everyday meaning, I think it is fair to say that this professor belonged to the category “anticharm.” However, if that is the reception given an idea judged dubious in a field as arcane as that, one can imagine the brutality exhibited toward “big ideas” that challenge received wisdom.
The fact is, though much is made of the opposition of advocates of religion to new ideas in science, there is also a strong tradition of opposition from scientists themselves. That is usually a good thing, for when an idea is misguided, scientists’ skepticism serves to protect the field from racing in the wrong direction. What’s more, when shown the proper evidence, scientists are quicker than just about anyone else to change their minds and accept strange new concepts.
Still, change is difficult for all of us, and established scientists who’ve devoted a career to furthering one way of thinking sometimes react quite negatively to a contradictory mode. As a result, to propose a startling new scientific theory is to risk exposing yourself to attack for being unwise, misguided, or just plain inadequate. There aren’t many foolproof ways to foster innovation, but one way to kill it is to make it unsafe to challenge the accepted wisdom. Nevertheless, that is often the atmosphere in which revolutionary advances must be made.
In the case of evolution, Darwin had plenty to fear, as evidenced, for example, by the reaction to Vestiges by his friend Adam Sedgwick, a distinguished professor at Cambridge who had taught Darwin geology. Sedgwick called Vestiges a “foul book” and wrote a scathing eighty-five-page review. Before opening himself up to such attacks, Darwin would amass a mountain of authoritative evidence to support his theory. That effort would occupy him for the next fifteen years, but in the end, it would be responsible for his success.
Through the 1840s and ’50s, Darwin’s family grew. His father died in 1848 and left him that considerable sum that Darwin had speculated about decades earlier while studying medicine—it came to about fifty thousand pounds, the equivalent of millions of dollars today. He invested wisely and became very prosperous, easily able to care for his large family. But his stomach issues continued to plague him, and he became yet more reclusive, missing even his father’s burial service due to his own illness.
All the while, Darwin continued to develop his ideas. He examined and experimented on animals, such as the pigeons his colleague would suggest he write about and, of course, those barnacles. He also experimented with plants. In one series of investigations, he tested the common notion that viable seeds could not reach distant oceanic islands. He attacked the question from many angles: he tested garden seeds that had been steeped for weeks in brine (to mimic seawater); he searched for seeds on birds’ legs and in their droppings; and he fed seed-stuffed sparrows to an owl and an eagle in the London Zoo and then examined their pellets. All his studies pointed to the same conclusion: seeds, Darwin found, are hardier and more mobile than people had thought.
Another issue Darwin spent considerable time on was the question of diversity: Why had natural selection produced such a wide variation between species? Here he took inspiration from the economists of his day, who spoke often of the concept of “division of labor.” Adam Smith had shown that people are more productive if they specialize, rather than each trying to create a complete article. The idea triggered Darwin to theorize that a given tract of land could support more life if its inhabitants were each highly specialized to exploit different natural resources.
Darwin expected that, if his theory were true, he would find more diverse life in areas where there was massive competition for limited resources, and he sought evidence to support or contradict that idea. Such thinking was typical of Darwin’s novel approach to evolution: while other naturalists looked for evidence of evolution in the development, over time, of family trees linking fossils and living forms, Darwin looked for it in the distribution and relationships among species in his own time.
To examine the evidence, Darwin had to reach out to others. So, though physically isolated, he solicited input from many and, like Newton, depended on the mail service—in particular a new, cheap “penny post” program that enabled him to build an unparalleled network of naturalists, breeders, and other correspondents who supplied him with information on variation and heredity. The arm’s-length back-and-forth allowed Darwin to test his ideas against their practical experience without exposing himself to ridicule by revealing his ultimate purpose. It also allowed him to gradually sort out who among his colleagues might be sympathetic to his views—and to eventually share, with that select group, his unorthodox ideas.
By 1856 Darwin had divulged his theory in detail to a few close friends. These included Charles Lyell, the foremost geologist of the day, and biologist T. H. Huxley, the world’s leading comparative anatomist. His confidants, especially Lyell, were encouraging him to publish, lest he be scooped. Darwin was then forty-seven and had been working on his theory for eighteen years.
In May 1856, Darwin began work on what he intended to be a technical treatise aimed at his peers. He decided to call it Natural Selection. By March 1858 the book was two-thirds done and running to 250,000 words. And then in June, Darwin received by mail a manuscript and a congenial cover letter from an acquaintance working in the Far East, Alfred Russel Wallace.
Wallace knew that Darwin was working on a theory of evolution and hoped that he would agree to pass to Lyell the manuscript—a paper outlining Wallace’s independently conceived theory of natural selection. Like Darwin, he’d been inspired to his theory by Malthus’s views on overpopulation.
Darwin panicked. The worst of what his friends had warned him about seemed to have come true: another naturalist had reproduced the most important aspect of his work.
When Newton heard claims of similar work he turned nasty, but Darwin was a far different man. He agonized about the situation and seemed to have no good alternative. He could bury the paper or rush to publish first, but those options were unethical; or he could help Wallace get it published and give up credit for his own life’s work.
Darwin sent the manuscript to Lyell with a letter on June 18, 1858:
[Wallace] has to-day sent me the enclosed, and asked me to forward it to you. It seems to me well worth reading. Your words have come true with a vengeance—that I should be forestalled.… I never saw a more striking coincidence; if Wallace had my MS. sketch written out in 1842, he could not have made a better short abstract! Even his terms now stand as heads of my chapters. Please return me the [manuscript], which he does not say he wishes me to publish, but I shall, of course, at once write and offer to send to any journal. So all my originality, whatever it may amount to, will be smashed, though my book, if it will ever have any value, will not be deteriorated; as all the labour consists in the application of the theory. I hope you will approve of Wallace’s sketch, that I may tell him what you say.
As it turned out, the key to who would be credited for the theory rested in Darwin’s observation that the value of his book lay in the applications he’d detailed. Not only had Wallace not made an exhaustive study of the evidence for natural selection, as Darwin had, but he had also failed to duplicate Darwin’s detailed analysis of how change can be of such magnitude as to generate new species, rather than merely new “varieties,” which we today call subspecies.
Lyell replied with a compromise: he and another of Darwin’s close friends, botanist Joseph Dalton Hooker, would read to the prestigious Linnean Society of London both Wallace’s paper and an abstract of Darwin’s ideas, and the two would be simultaneously published in the society’s Proceedings. As Darwin agonized over the plan, the timing could hardly have been worse. Not only was Darwin sick with his usual maladies, but his old friend biologist Robert Brown had recently died, and his tenth and youngest child, Charles Waring Darwin, just eighteen months old, was gravely ill with scarlet fever.
Darwin left the matter for Lyell and Hooker to handle as they saw fit, and so on July 1, 1858, the secretary of the Linnean Society read Darwin’s and Wallace’s papers to the thirty-odd fellows present. The readings drew neither hoots nor applause, only stony silence. Then came the reading of six other scholarly papers, and, in case anyone was left awake after the first five, saved for last was a lengthy treatise describing the vegetation of Angola.
Neither Wallace nor Darwin attended. Wallace was still in the Far East and unaware of the proceedings in London. When later informed, he graciously accepted that the matter had been handled fairly, and in future years he would always treat Darwin with respect and even affection. Darwin was ill at the time, so he probably wouldn’t have traveled to the meeting in any case, but as it turned out, while the meeting transpired, he and his wife, Emma, were burying their second deceased child, Charles Waring, in the parish churchyard.
With the presentation at the Linnean Society, after twenty years of hard work to develop and back up his theory, Darwin had finally exposed his ideas to the public. The immediate reaction was, to say the least, anticlimactic. That everyone present had missed the significance of what they’d heard was perhaps best reflected in comments by the society’s president, Thomas Bell, who on his way out lamented, as he later put it, that the year had not “been marked by any of those striking discoveries which at once revolutionize, so to speak, [our] department of science.”
After the presentation at the Linnean Society, Darwin moved quickly. In less than a year, he reworked Natural Selection into his masterpiece, On the Origin of Species. It was a shorter book, and targeted at the general public. He finished the manuscript in April 1859. By then he was exhausted and, in his own words, “weak as a child.”
Always cognizant of the need to nurture a consensus in his favor, Darwin arranged for Murray, his publisher, to distribute a great many complimentary copies of the book, and Darwin personally mailed self-deprecating letters to many of the recipients. But in writing his book, Darwin had actually been careful to minimize any theological objections. He argued that a world governed by natural law is superior to one governed by arbitrary miracles, but he still believed in a distant deity, and in Origin of Species he did everything he could to create the impression that his theory was not a step toward atheism. Rather, he hoped to show that nature worked toward the long-term benefit of livings things by guiding species to progress toward mental and physical “perfection” in a manner consistent with the idea of a benevolent creator.
“There is grandeur in this view of life …,” he wrote, “having been originally breathed into a few forms or into one … whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
The reaction to Origin of Species was not muted. His old mentor Professor Sedgwick of Cambridge wrote, for example, “I have read your book with more pain than pleasure … parts I read with absolute sorrow, because I think them utterly false and grievously mischievous.”
Still, by presenting a superior theory, better supported by evidence, and in a somewhat mellower time, On the Origin of Species didn’t stimulate as much ire as Vestiges had. Within a decade, the debate among scientists was largely over, and by the time of Darwin’s death, ten years after that, evolution had become almost universally accepted and a dominant theme of Victorian thought.
Darwin had already been a respected scientist, but with the publication of his book he became, like Newton after Principia, a public figure. He was showered with international recognition and honors. He received the prestigious Copley Medal from the Royal Society; he was offered an honorary doctorate by both Oxford and Cambridge; he was granted the Order of Merit by the king of Prussia; he was elected a corresponding member of both the Imperial Academy of Sciences, in St. Petersburg, and the French Academy of Sciences; and he was granted an honorary membership by the Imperial Society of Naturalists, in Moscow, as well as by the Church of England’s South American Missionary Society.
Like Newton’s, Darwin’s influence stretched far beyond his scientific theories to encompass new ways of thinking about totally unrelated aspects of life. As one group of historians wrote, “Everywhere Darwinism became synonymous with naturalism, materialism, or evolutionary philosophy. It stood for competition and co-operation, liberation and subordination, progress and pessimism, war and peace. Its politics could be liberal, socialist, or conservative, its religion atheistic or orthodox.”
From the point of view of science, though, Darwin’s work, like Newton’s, was only a beginning. His theory proposed a fundamental principle governing the way the characteristics of species change over time in response to environmental pressures, but scientists of the day remained completely in the dark with regard to the mechanics of how heredity functions.
Ironically, at the very time Darwin’s work was being presented to the Linnean Society, Gregor Mendel (1822–1884), a scientist and monk in a monastery in Brno—now part of the Czech Republic—was in the midst of an eight-year program of experiments that would suggest a mechanism for heredity, at least in the abstract. He proposed that simple characteristics are determined by two genes, one contributed by each parent. But Mendel’s work was slow to catch on, and news of it never reached Darwin.
In any case, an understanding of the material realization of Mendel’s mechanism would require the advances of twentieth-century physics—especially quantum theory and its products, such as X-ray diffraction techniques, the electron microscope, and transistors enabling the creation of digital computers. Those technologies eventually revealed the detailed structure of the DNA molecule and the genome, and allowed genetics to be studied on the molecular level, finally enabling scientists to begin to understand the nuts and bolts of how inheritance and evolution occur.
Even that, though, is just a beginning. Biology seeks to understand life on all its levels, all the way down to the structures and biochemical reactions within the cell—the attributes of life that are the most direct results of the genetic information we carry. That grand goal, no less than the reverse engineering of life, is no doubt—like the physicists’ unified theory of everything—far in our future. But no matter how well we grow to understand the mechanisms of life, the central organizing principle of biology will probably always remain that nineteenth-century epiphany, the theory of evolution.
Darwin himself was not the fittest specimen, but he survived to old age. In his late years, his chronic health issues improved, though he became constantly tired. Still, he kept working until the end, publishing his last paper, The Formation of Vegetable Mould through the Action of Worms, in 1881. Later that year, he began to experience chest pains upon exercise, and at Christmastime he had a heart attack. The following spring, on April 18, he had another heart attack and was barely brought back to consciousness. He muttered that he was not afraid to die, and hours later, around four the following morning, he did die. He was seventy-three. In one of his last letters, written to Wallace, he had said, “I have everything to make me happy and contented, but life has become very wearisome.”
*Robert Chambers, an Edinburgh publisher of popular periodicals, was officially named as the book’s author in 1884, thirteen years after his death, but Darwin had guessed that Chambers had written the book after a meeting with him in 1847.
