Confusion and Heresy

Four months after the Beagle’s return, Darwin began to hear back from his experts about his collection of fossils and carcasses. At first they did nothing but confuse him. Owen had inspected the fossil mammals and announced that they were gigantic variations on the animals that still lived in South America. The rodents were the size of hippos, the anteaters the size of horses. Why, Darwin wondered, was there a continuity between extinct animals and the ones alive on the same spot on Earth? Could the living animals have descended, in a modified form, from the fossil ones?

Darwin had given his Galápagos birds to lames Gould, one of Britain’s leading ornithologists. He hadn’t thought much of them when he had collected them, and when he heard Gould speak about them at a meeting of the Zoological Society, he regretted his carelessness. Judging from their beaks, Darwin had identified many of his birds as finches, wrens, and blackbirds. But Gould announced that they were all finches. They simply had wrenlike or blackbird‑like beaks, which allowed them to eat particular kinds of foods.

And later, when Darwin paid a visit to Gould’s office, Gould showed that he had made an even more grievous mistake. Darwin hadn’t noted exactly which island he had gotten most of his birds from, because it seemed unimportant at the time. He had happened to note that three mockingbirds had come from three different islands, and Gould showed him that the mockingbirds belonged to three new–and separate–species.

Darwin wondered why there would be three different species of mockingbirds so close to one another. And were separate species of finches living on separate islands as well? Darwin contacted FitzRoy and asked for some of the birds collected by the Beagle crew to be sent to Gould. Fortunately, the crewmen had done a better job than Darwin, jotting down which islands they had shot their birds on. And just like the mockingbirds, the finches of different islands belonged to separate species.

Something, Darwin realized, was very wrong. Why should there be so many unique species on these similar islands? He opened his notebooks and tried to figure out an explanation for the finches of the Galápagos. To the people around him, he seemed unchanged as he went on with his geological work, writing about coral reefs and rising plains and the shape of volcano cones. But in private he was obsessed with an extraordinary thought. Perhaps the finches had not been created in their current form. Perhaps they had evolved.

The land on which species lived, after all, was not eternally unchanging. Darwin’s finches now lived on islands that had at some point breached out of the ocean. Once the Galápagos had emerged, an original species of finch might have colonized them from South America, and over time its descendants on each island had changed into the distinct species with their distinct bodies that were now adapted to their way of life. The descendants of the original settlers branched apart into distinct lineages. The same branching might have happened among the mammals of Patagonia. The animals that left behind the gigantic fossils that Darwin had discovered might have given rise to today’s mammals, with their smaller bodies.

In his notebook Darwin sketched out a tree, with old species branching into new ones.

Darwin found this idea terrifying. He began to suffer from heart palpitations and stomach‑aches, to wake up out of strange dreams in the middle of the night. He knew that whatever laws governed finches or anteaters must also govern human beings. He began to think of humans as merely one more species of animal, albeit with some peculiar mental gifts. “It is absurd to talk of one animal being higher than another,” he wrote in his notebooks. “People often talk of the wonderful event of intellectual Man appearing–the appearance of insects with other senses is more wonderful…. Who with the face of the earth covered with the most beautiful savannas & forests dare say that intellectuality is the only aim in the world?”

Perhaps humans were the result of evolution, just like the finches. Darwin visited the zoo to look at a newly captured orangutan named Jenny and saw in her face the expressions he could also see in babies. “Man from monkeys?” he wrote.

Although his ideas were still embryonic, Darwin knew that they were dangerous. A public announcement that humans had evolved might alienate him from Lyell and the other naturalists whom he respected, and on whom his career depended. Nonetheless Darwin kept scribbling in his notebooks, working out his theory and gathering facts to support it.

Darwin searched for signs of how traits were handed down from one generation to the next and how they changed in the process. He interrogated gardeners and zookeepers and pigeon fanciers. He interviewed his hairdresser about breeding dogs. Although he could see signs that species were not eternal, he still didn’t know of any way a species could take on a new form. Lamarck had claimed that an animal could change over its lifetime and pass on its acquired characteristics to its offspring, but there was little evidence that this actually happened. Darwin looked for a different explanation for how evolution could unfold.

He found it in a gloomy book about humanity’s inevitable sufferings. In 1798 Thomas Malthus, a country parson, had written An Essay on the Principle of Population. In it he pointed out that a country’s population, if it is unchecked by starvation or sickness, can explode in a matter of years. If every couple raised four children, the population could easily double in 25 years, and from then on, it would keep doubling. It would rise not arithmetically–by a factor of 3, 4, 5, and so on–but geometrically–by a factor of 4, 8, and 16.

If a country’s population did explode this way, Malthus warned that there was no hope that its food supply could keep up. Clearing new land for farming or improving the yields of crops might produce a bigger harvest, but it could only increase arithmetically, not geometrically. Unchecked population growth inevitably brought famine and misery. The only reason that humanity wasn’t already in perpetual famine was because its growth was continually checked by forces such as plagues, infanticide, and simply putting off marriage till middle age.

Malthus pointed out that the same forces of fertility and starvation that shaped the human race were also at work on animals and plants. If flies went unchecked in their maggot making, the world would soon be knee‑deep in them. Most flies (and most members of every species) must die without having any offspring.

In Malthus’s grim essay, Darwin found the engine that could push evolution forward. The fortunate few who got to reproduce themselves wouldn’t be determined purely by luck. Some individuals would have traits that would make them better able to survive under certain conditions. They might grow to be big, they might have a particularly slender beak, they might grow thicker coats of fur. Whichever individuals were born with these traits would be more likely to have offspring than weaker members of their species. And because offspring tend to be like their parents, they would pass on those winning traits to their young.

This imbalance would probably be too small to see from one generation to the next. But Darwin was already comfortable with imperceptible geological changes producing mountains. Here was mountain making of a biological sort. If a population of birds ended up on a Galápagos island, the individual birds that were best suited to life on the island would produce the next generation. And with enough time, these changes could produce a new species of bird.

Darwin found a good analogy for this process in the way farmers tend their crops. They breed their plants by comparing how well each stalk or tree turns out. They then use the seeds only from the best ones to plant the next generation. With enough breeding the crops become distinct from other varieties. But in nature there is no farmer. There are only individual animals and plants competing with one another to survive, for light or water or food. They undergo a selection as well, a selection that takes place without a selector. And as a result, Darwin recognized, life’s design could come about naturally, with no need for a string of individual acts of creation.

“Like Confessing a Murder”

Darwin took a little time away from scribbling heresies to find a wife. Before his voyage he had fallen in love with a woman named Fanny Owen, but shortly after he set sail she married another man. When he got home he wondered if he should get married at all. Ever the methodical scientist, Charles drafted a pro‑and‑con balance sheet. He wrote “Marry” on the left side, and “Not Marry” on the right, and “This is the question” in the middle. This nuptial Hamlet reasoned that as a single man he would have more time for science and for conversations in men’s clubs. He wouldn’t have to earn enough to support children. On the other hand, a wife would offer “female chitchat” and constant companionship in old age. He added up the columns and made his conclusion: “Marry–Marry–Marry. QED.”

Darwin chose his cousin Emma Wedgwood. He had no interest in the sophisticated women he encountered in London. Instead, he looked back to his mother’s niece, who had grown up as he did, in the country. Emma had already become interested in Darwin during his occasional visits to the Wedgwood house. She was happy to be courted by him, although he wooed her awkwardly with a series of oblique comments and half‑made gestures. She was completely unprepared when he nervously blurted out to her one day that he wanted to marry her. She said yes, but she was so stunned that she promptly went off to teach her Sunday school class.

Soon, though, Emma grew happy with the thought of marrying a man she considered “perfectly sweet‑tempered.” Darwin, meanwhile, worried that his time on the Beagle had made him too unsociable for marriage, but he found hope in the prospect of marrying Emma. “I think you will humanize me,” he wrote to her, “and soon teach me there is greater happiness than building theories and accumulating facts in silence and solitude.”

Emma’s only worry came when Charles talked about nature and the laws that might govern it. Emma, a devout Anglican, could tell that Charles had his doubts about the Bible. “Will you do me a favor?” she wrote to him. She asked him to read part of the Gospel according to John: “A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.” If he began with love, Darwin might become a proper Christian.

He promised Emma that he felt “earnest on the subject.” But a look in his notebook at the time would have shown he was not being entirely honest. He was wondering if religion was more a matter of instinct than of any love of a real God. It was his love for Emma that kept him from telling her all his thoughts.

After they were married, Charles brought Emma to London, and they settled into comfortable monotony. Emma’s anxiety about her husband’s soul continued, and she wrote him more letters. In one that she wrote in 1839, she worried that Charles was so consumed with finding the truth in nature that he shut out any other sort of truth–the sort that only religion could reveal. Believing only what could be proved would keep him from accepting “other things which cannot be proved in the same way & which if true are likely to be above our comprehension.” She begged Charles not to forget what Jesus had done for him and the rest of the world. Darwin put away her letter without a reply, although he would remember it for the rest of his life.

In 1839 Darwin published Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of HMS Beagle Round the World, Under the Command of Captn. FitzRoy, R.N. It was a huge success in Britain and cemented Darwin’s fame as a naturalist. By then Charles and Emma had been married three years and had two children, and they decided it was time to leave London. They were tired of the crime, the coal dust that blackened their clothes, the horse dung that clung to their shoes. They wanted to raise their children in the countryside, where they had grown up. They picked out an estate called Down House, an 18‑acre farm in Kent, 16 miles from London. Darwin became a gentleman farmer, planting flowers, buying a horse and a cow. He stopped mingling in the scientific societies altogether. He got whatever information he needed by letter or from carefully selected weekend guests. (Erasmus hated leaving London to visit his brother; he called their house “Down at the Mouth.”)

All the while, Darwin continued mulling his theory of evolution in secret. He wrote down an argument for natural selection, and when he finished it, in 1844, he had no idea what to do next. He didn’t even know how to talk to anyone about it. To support his theory he had been extracting information from dozens of people, but he had never let any of them know what it was for. The boy who was frightened of telling his father he couldn’t become a doctor now had become a man frightened of telling anyone of his dangerous ideas.

But in the end Darwin had to tell someone. He had to find a scientist who could give him a qualified judgment, who might see some fatal flaw he had overlooked. He chose Joseph Hooker, a young botanist who had studied the plants from Darwin’s voyage on the Beagle, and whom Darwin thought might be open‑minded enough not to call him a blasphemer. He wrote to Hooker:

I have been now ever since my return engaged in a very presumptuous work, and I know no one individual who would not say a very foolish one. I was so struck with the distribution of the Galápagos organisms, etc., that I determined to collect blindly every sort of fact which could bear any way on what are species. I have read heaps of agricultural and horticultural books, and have never ceased collecting facts. At last gleams of light have come, and I am almost convinced (quite contrary to the opinion I started with) that species are not (it is like confessing a murder) immutable… I think I have found out (here’s presumption!) the simple way by which species become exquisitely adapted to various ends. You will groan, and think to yourself, “on what a man have I been wasting my time and writing to.” I should, five years ago, have thought so.

Hooker turned out to be as open‑minded as Darwin had hoped. “I shall be delighted to hear how you think this change may have taken place,” he wrote back, “as no presently conceived opinions satisfy me on the subject.”

Hooker’s response gave Darwin enough nerve to show his essay to Emma a few months later. He knew that she might be disturbed, but he wanted her to have the essay published posthumously if he should die too soon. Emma read it. She did not weep or faint. She merely pointed out where the writing got murky. When Darwin wrote that he could imagine natural selection producing something even as complex as an eye, she wrote, “a great assumption.”

Back Into Hiding

With two people privy to his secret, Darwin was slowly gaining confidence about publishing his essay. But it vanished completely a month later. In October 1844 a book rolled off the presses called Vestiges of the Natural History of Creation. Its author, a Scottish journalist named Robert Chambers, chose to be anonymous–going so far as to hide the trail by which his publisher paid him royalties. He was wise to be so cautious.

Vestiges started harmlessly enough, describing the solar system and the neighboring stars, surveying how the laws of physics and chemistry explained Earth’s formation out of a gaseous disk. Chambers worked through the geological record as it was then understood, noting the rise of fossils through history. The simple appeared first, and then the complex. As time went by, higher and higher forms of life left their mark. And then Chambers made a scandalizing claim. If people could accept that God assembled the heavenly bodies by natural laws, “what is to hinder our supposing that the organic creation is also a result of natural laws, which are in like manner an expression of his will?” That would make more sense than God stepping in to create every species of shrimp or skink. “Surely this idea is too ridiculous to be for a moment entertained.”

As for how those natural laws worked, Chambers offered a mishmash of secondhand chemistry and embryology. He thought that a spark of electricity might turn inanimate matter into simple microbes. After that, life would evolve by altering its development. Chambers relied here on the outdated ideas of German biologists. He pointed out that birth defects often consisted of a failure to carry out all the steps of development–a baby might be born with a heart, for instance, that had only two chambers, like a fish, instead of four. Presumably these defects were the result of “a failure of the power of development in the system of the mother, occasioned by weak health or misery.” But if the opposite were the case, a mother might give birth to a child who had passed through a new stage of development. A goose might give birth to a gosling with the body of a rat–producing the first duck‑billed platypus. “Thus the new production of new forms, as shown in the pages of the geological record, has never been anything more than a new stage of progress in gestation.”

Chambers didn’t think his readers should be scandalized that they had descended from fishes. The sequences of events he was proposing were “wonders of the highest kind, for in each of them we have to trace the effect of an Almighty Will, which had arranged the whole in such harmony with external physical circumstances.” The middle‑class British reader of Vestiges could go on with his life as he had before, still guided by the same moral compass. “Thus we give, as is meet, a respectful reception to what is revealed through the medium of nature, at the same time that we fully reserve our reverence for all we have been accustomed to hold sacred, not one tittle of which it may ultimately be found necessary to alter.”

Vestiges was a huge hit, selling tens of thousands of copies. For the first time a broad English audience was introduced to the concept of evolution. But the leading scientists of Britain attacked it bitterly. “I believe some woman is the author,” wrote Adam Sedgwick, “partly from the utter ignorance the book displays of all sound physical logic.” Sedgwick was even more horrified by how such a view of life could undermine decency. If the book were true, he declared, “religion is a lie; human law a mass of folly and a base injustice; morality is moonshine.”

The violence of the backlash shocked Darwin and sent him back into scientific hiding. He had not realized just how strongly Sedgwick and his other teachers were opposed to evolution. But he would not abandon his theory. Instead, he would figure out how to avoid Chambers’ fate.

Darwin could see that Vestiges had clear weaknesses. Chambers had simply read other people’s ideas and crushed them together into a shoddy argument. In some ways, Darwin was guilty of the same failing–his ideas were based on things he had read or heard from dozens of people–Lyell, Malthus, even his hairdresser. While he was recognized now as an authority on geology, he worried that he’d be treated as a dilettante when it came to biology. In order to be taken seriously, he had to show himself to be a first‑class naturalist, able to wrestle with the complexities of nature.

He turned to the Beagle specimens he hadn’t yet examined in the eight years that he had been back. In one of his bottles there was a barnacle. Although most people think of barnacles as nothing more than something to scrape off boat hulls, they are actually some of the most unusual creatures of the ocean. Initially zoologists thought they were mollusks, like clams and oysters, with their hard shells cemented to a flat surface. In fact, barnacles are crustaceans, like lobsters and shrimp. It was only in 1830 that their true identity was discovered, when a British army surgeon looked at their larvae and found that they had a resemblance to young shrimp. Once barnacle larvae are released into seawater, they search for a place to land–whether it is a ship’s hull or a clamshell–and settle headfirst onto their chosen surface. They then lose most of their crustacean anatomy, developing instead a conical shell, out of which they extend feather‑like feet that they use to filter food.

In 1835, off the coast of Chile, Darwin had collected a species of barnacle the size of a pinhead, latched to the inside of a conch shell. Looking at them under his microscope, he now realized that each barnacle was actually two–a large female with a minuscule male attached to it. At the time, scientists were most familiar with hermaphroditic forms of barnacles, equipped with both male and female reproductive organs. The pinhead barnacle was so strange that Darwin was sure it was a new genus.

Darwin was off on another long journey. At first he planned simply to write a short paper describing his discovery. But to do so, he had to figure out where among the many barnacle species he should classify it. He asked Owen to loan him some barnacles and to give him some advice on how to do the work properly.

Owen explained to Darwin that he needed to link his barnacle–no matter how strange it might be–to the basic crustacean archetype. By the 1840s, Owen had decided that archetypes were the key to zoology. Owen himself tried to reconstruct the vertebrate archetype, which he imagined was little more than a spinal column, ribs, and a mouth. This body plan didn’t exist in nature, Owen claimed; it was only a blueprint in the mind of God, on which He based more and more elaborate forms. You could see the connection to the archetype if you compared different vertebrates.

Take, for instance, a bat, a manatee, and a bird. The bat has a wing made of a membrane stretched over elongated fingers. A manatee has a paddle for swimming. A bird has a wing as well, but it consists of feathers pinned to hand bones that have been fused together into a hinged rod. Each of these vertebrates has limbs that are adapted to its way of life, but they also correspond to one another precisely, bone for bone. They all have digits connected to marble‑like wrist bones, which are connected to two long bones that meet at the elbow with a single long bone. These correspondences (which scientists call homologies) revealed to Owen a common body plan.

Owen urged Darwin to look for homologies between barnacles and other crustaceans. Darwin privately thought that Owen’s archetype was nonsense. He thought that the similarities among vertebrates were a sign of their descent from a common ancestor. But to trace the evolution of barnacles from less peculiar crustaceans, Darwin would have to look at a lot of barnacles (1,200 species are known today). He borrowed collections from other naturalists, he studied fossil barnacles, and he even got hold of the British Museum’s entire stash. Darwin would end up spending eight years studying barnacles. All the while, his explanation of evolution, an idea as revolutionary as Copernicus’s sun‑centered cosmology, sat sealed on a shelf.

Why the delay? Fear may have made Darwin procrastinate as he put off the inevitable confrontation with his mentors. Another reason may have been that Darwin was tired. He had taken a grueling five‑year voyage, followed by eight fierce years of writing books and papers. His health had deteriorated after his return to England, to the point that he now was regularly devastated by bouts of vomiting. Darwin was in his mid‑thirties and ready for some peace.

And yet another part of the delay was grief. His favorite daughter, Anne, died of the flu in 1851 at age 10. As he witnessed her undeserved agony, Darwin gave up on the angels. After Anne’s death, he couldn’t talk to Emma about his crumbling faith. Studying barnacles may have become a way to hide from the pain.

But fear, exhaustion, and grief aside, Darwin was enchanted by his barnacles. They turned out to be a perfect group of animals to study in order to learn how evolution worked. Darwin could see, for instance, how the ancestors of his Chilean barnacles could have descended from hermaphrodites, which had evolved through transitional forms until they began producing males and females. Darwin was also impressed by the variation that he found among the members of individual species of barnacles. No part of the barnacle anatomy was uniform. Here, Darwin realized, was a huge reservoir of raw material for natural selection to work on. Originally he had thought that a species would be subject to natural selection only at certain times–when islands emerged or continents began to sink, for instance. But with so much variation to choose from, natural selection could actually be at work all the time.

None of these thoughts made it explicitly into Darwin’s barnacle writings. He published a 1,000‑page tome, for which he won praise, awards, and the respect he wanted as a naturalist. By 1854 he was ready to get back to thinking about natural selection.