Darwin's Ghosts

by Rebecca Stott

  In Leicester, where Wallace moved in 1844 to take up a position as a teacher at the Collegiate School when his brother’s business began to decline, he spent all his spare time in the public library, which had the finest collection of books he had come across in his travels thus far. Here in the cold and drafty library, he reread The Voyage of the Beagle, astonished by Darwin’s descriptions of South American forests, birds, flowers, and strange peoples; then, inspired by Darwin’s enthusiasm for Humboldt, he read Humboldt’s Personal Narrative of Travels in South America and Prescott’s History of the Conquests of Mexico and Peru. While teaching interminable rote-learned Latin lessons, in which he barely kept ahead of his students, Wallace dreamed of rain forests, of putting himself in Darwin’s shoes, feeling the barrel of a gun in his hand, taking aim at imaginary birds, riding on horseback up into remote mountain ranges in search of new species.

  Sometime in 1844, Wallace took down Malthus’s Essay on the Principle of Population from the shelves of the Leicester library, a book that made a bleak contrast with the color and exoticism of Darwin’s South American landscapes. “It was,” Wallace wrote later, “the first work I had yet read treating of any of the problems of philosophical biology and its main principles remained with me as a permanent possession, and twenty years later gave me the long-sought clue to the effective agent in the evolution of organic species.”

  Wallace was lucky. At the Leicester public library he not only found Malthus but also met another reader, Henry Walter Bates, the clever, bookish nineteen-year-old son of a local hosiery manufacturer. Bates was more interested in natural philosophy in general and beetles in particular than he was in running his father’s factory. Eager to impress his new friend, he challenged Wallace to guess how many different beetles might be found in the small district near a town. Wallace, who now knew a good deal about local plant diversity, knew very little about beetles. He guessed fifty. Bates took Wallace to his father’s elegant redbrick house in Queen’s Street, where he showed him the hundreds of different beetles he had found and identified in the streets and parks of the city and had pinned and carefully arranged behind glass in his study. There were, he told Wallace breathlessly, perhaps a thousand different types within ten miles of this single town. He opened a copy of a thick volume on his shelves to show Wallace descriptions of more than three thousand British species.

  Wallace was fascinated by the close attention Bates had given in his collection to the location and range of the Leicester beetles. Bates was already a biogeographer, though neither he nor Wallace would have used the word. In ninth-century Basra, Jahiz, making lists of species attracted to the light from a night campfire, had been one, too. Wallace was a convert to Bates’s methods. He invested in a collecting bottle, pins, and a storage box and roamed the local bookshops for a copy of Stephens’s Manual of British Coleoptera at a wholesale price. Every Wednesday and Saturday afternoon, as the summer blossomed in Leicestershire, he took his pupils away from their Latin lessons and walked them to the grounds of Bradgate Park, a “wild, neglected park with the ruins of a mansion,” where they collected and identified beetles with Bates and his younger brother Frederick, setting sugared traps, turning over leaves, and kicking over rotted logs and rocks. Every scuttling new find was carefully numbered, labeled, pinned, and added to a map.

  Wallace never settled anywhere for long. Compelled to return to Wales in 1846 to attend to William’s business after his brother’s sudden death from pneumonia, Wallace extended his search to Welsh insects, collecting them through the summer along the line of levels up the Vale of Neath to Merthyr Tydfil, where he took a job as a surveyor for the new railway. He carried beetle jars and boxes in his bag with his surveying equipment and wrote every few days to Bates, sending him rare specimens and details of his finds. Other family members migrated back to Wales that summer, but Wallace felt restless. His sister, recently returned from teaching at a college in Macon, Georgia, told him stories of cotton fields and cotton boats, the coming of the railways, the slaves and the native Americans and unimaginable beetles and butterflies for which she had no name. They all talked of emigration.

  Insects arranged as they would be in a cabinet (nineteenth-century engraving).

  Engraving by R. Scott after T. Brown, Wellcome Library, London

  Wallace may have been restless in Wales, impatient for a clear sense of vocation and direction, but he was not bored. The scandalous and much discussed red-leathered book Vestiges of the Natural History of Creation arrived in Neath sometime in 1845. In Welsh scientific circles, as it was in London, Vestiges was the book of the season. Wallace was utterly beguiled by the book’s speculations; the implications of species transformation were breathtaking. He wrote to Bates asking whether he had read it, only to discover to his disappointment that Bates thought the book generalized. Wallace replied in robust defense:

  I do not consider it as a hasty generalization, but rather as an ingenious speculation strongly supported by some striking facts and analogies but which remains to be proved by more facts & the additional light which future researches may throw up on the subject— It at all events furnishes a subject for every observer of nature to turn his attention to; every fact he observes must make either for or against it, and it thus furnishes both an incitement to the collection of facts & an object to which to apply them when collected.—I would observe that many eminent writers give great support to their theory of the progressive development of species in animals & plants.

  He told Bates to read Lawrence’s Lectures on Man. If Vestiges would not persuade him about the “progressive development of species,” perhaps Lawrence’s essay would.

  Vestiges was indeed an incitement to action. It seemed to Wallace as though he had been waiting for this book all his life. It put together everything he had been baffled by, drew all his interests and questions together—geology, plant and animal distribution, astronomy, species diversification, fossils, variation—into a narrative of unstoppable species change that was utterly persuasive. It was self-evident. If there wasn’t enough evidence to support the Vestiges hypothesis yet, someone had to find it. Here was his vocation, his reason for being. He would collect, not as a pastime, not in his spare time, not in the fields of Wales, but on islands and in jungles and river valleys where no one had been before. He would collect evidence to prove species mutation, and Bates would come with him.

  Wallace plunged into preparations for a journey even before he and Bates had agreed on a destination. When Bates came to visit, an excited conversation about W. H. Edwards’s recently published A Voyage Up the Amazon settled them both on Brazil; now they had to find ways to fund the journey. Neither of them had any money. Bates was working as a clerk for Allsopps, the brewers at Burton-on-Trent. His father thought his travel plans were preposterous and refused to fund the journey, so they began to wonder if they might make their living from collecting and selling specimens along the way. Fanny Wallace, a keen Francophile and traveler, took Wallace to London and then to Paris to show her brother the collections in the British Museum and the Jardin des Plantes and served as interpreter in his conversations with professional collectors, agents, and taxidermists there. “I begin to feel rather dissatisfied with a mere local collection,” he wrote to Bates, “—little is to be learnt by it. I shd. like to take some one family, to study thoroughly—principally with a view to the theory of the origin of species. By that means I am strongly of opinion that some definite results might be arrived at.”

  The two men went to meet Samuel Stevens, a natural history agent and dealer based on Bloomsbury Street, and offered him their services. They talked to as many potential buyers and museum curators as would give them the time of day, but getting buyers to take them seriously was not always easy—they were, after all, the sons of tradesmen and barely out of boyhood. Finally, when they were confident that Samuel Stevens would buy specimens from them, they bought their tickets for the boat, packed up small trunks of belongings, and prepared to depart.


  The two collectors found Brazil difficult at first, even disappointing. The rain forests seemed oddly empty. “On my first walk into the forest,” Wallace wrote, “I looked about, expecting to see monkeys as plentiful as the Zoological Gardens, with humming-birds and parrots in profusion.” They were just not visible. As the months went by and their eyes readjusted, they began to see—and catch—more specimens. Stevens was delighted with the first crates of insects that arrived in London and gave the two collectors good prices for them. The two friends separated for a few months, heading in different directions in order to cover more territory. “The more I see of this country, the more I want to,” Wallace told Stevens. It took Wallace most of his time in Brazil to adjust to the cultural differences, to learn his trade, to experiment with methods of preservation, storage, and trapping, and to find ways of getting around, sleeping, eating, communicating, and dealing with ants, fevers, and loneliness.

  Everywhere he went he seemed to be treated like a rare species himself: “One of the most disagreeable features of travelling or residing in this country is the excessive terror I invariably excite,” he wrote.

  Wherever I go dogs bark, children scream, women run & men stare with astonishment as though I were some strange & terrible cannibal monster.… One day when in the forest an old man stopped to look at me catching an insect. He stood very quiet till I had captured, pinned and put it in my collecting box when he could contain himself no longer, but bent himself almost double & enjoyed a hearty roar of laughter.

  Wallace rarely complained. Even after he lost his entire cargo of exotic species, his notes, and everything he owned when the ship in which he was returning to England caught fire and sank, he tried to be optimistic. “And now everything was gone,” he wrote, “and I had not one specimen to illustrate the unknown lands I had trod, or to call back the recollection of the wild scenes I had beheld! But such regrets I knew were vain, and I tried to think as little as possible about what might have been and to occupy myself with the state of things that actually existed.” It was a temperament that would shield him from disappointment later.

  Back in England, his notes now scattered somewhere on the ocean floor, among broken crates of beetles and birds, Wallace was forced to distill and summarize, to look for the general laws beyond the particular facts he had gathered. He published two books, his Narrative of Travels on the Amazon and Rio Negro and a shorter book, Palm Trees of the Amazon and Their Uses. As the details fell away he began to think on a larger scale about the geographical limits of species. Since he had seen Bates’s beetle collection, he had always been scrupulous about geographical precision in his collecting. Species range was of utmost importance to him. All the different species of monkeys had a specific geographical area in which they roamed, he told his audiences, the edges of which were marked by rivers or mountain ranges. “I soon found,” he told the Zoological Society back in London, “that the Amazon, the Rio Negro and the Madeira formed the limits beyond which certain species never passed.”

  By the time Wallace reached the Malay Archipelago in 1854, five years after he had determined to become the proof gatherer for the still unproved theories of progressive species development outlined in the scandalous Vestiges, he was in a unique situation among European naturalists: poor but financially independent, he was free from obligations to an institution, patron, or business, and he had no family to protect from embarrassment or personal wealth to risk. He had come to see and respect the diversity of religious belief and ritual practiced all around him in the jungles and villages of the Amazon, but he did not have to reconcile his discoveries with a personal creed or God. He had long accepted transmutation as an explanation for species diversity, but he was still looking for the mechanism by which species had diversified. Brazil had not given him the weight or density of species he needed to find that mechanism, and the sheer labor of collecting and surviving had kept him distracted by detail.

  But things were about to change.

  Islands were crucial to the discovery of natural selection for Wallace, as they were for Darwin. Wallace had come to the Malay Archipelago, a scattered string of islands off Java, primarily in search of birds of paradise and other rarities that would fetch high prices back in London, but these islands, each with its own unique ecosystem, would also provide him with a series of natural laboratories in which to test his developing theories. What Wallace was looking for—evidence of geographical species range that would help him understand how species had come to be—was much more intensely illustrated in the Malay Archipelago than it had been on the Amazon. He had found his way to the right place.

  Wallace’s mind and imagination moved constantly between the large-scale and the small-scale. During the day he worked to identify the minute differences between species, attending to plumage or butterfly wing or beetle thorax patterns and colors; at night he pored over maps, studying landmasses that covered thousands of miles, plotting out the edges and overlaps between different species ranges and thinking back deep into time. Like Jahiz, he was interested in the relationship between species and location, asking, for instance, why one moth lived in the desert while another lived only in the mountains. But as a biogeographer, Wallace was doing something quite different from Jahiz. Jahiz had had no thesis to prove. The diversity and range of moths that gathered in the light of the desert fire at night, the fact that each moth or insect seemed to occupy its own unique landscape, demonstrated for him the ubiquity of Allah’s grace and the brilliance of his natural design. When Wallace mapped out the territories of primates, however, noting that there seemed to be a “boundary line” that the great apes “never pass,” he was looking for clues that would help him understand how species had diversified over millions of years.

  Wallace was getting closer to an answer to the species question. In 1855, while in Sarawak, he decided to nail his colors to the mast and publish a paper on transformism. The paper was published in the Annals and Magazine of Natural History in 1855. No one wrote to him about it. No one seemed even to have noticed it. Wallace felt the silence keenly.

  In 1856, he made a major breakthrough. Sailing for the eastern end of the archipelago, he missed a connection and was stranded in Lombok and Bali for two months with Ali. The two islands, he pointed out to Ali as they recorded and labeled hundreds of specimens, though they were very close geographically and similar in terrain, seemed to be two “quite distinct zoological provinces.” One set of birds belonged zoologically—and, by inference, by descent—to Australia, the other to Asia. Wallace drew a line on the map laid out in his hut, a line that formed the boundary between what we would now call ecozones, large areas of the earth’s surface where animals and plants developed in relative isolation for thousands of years, the landmasses on which they lived separated from one another by oceans or deserts or mountain ranges that prevented animals and plants from migrating. The line he had drawn, the Wallace Line, would make his name famous. Lombok and its animals and plants lay on one side of it and Bali on the other. Unknown to Wallace, the line followed the course of a deep-sea channel marking the contour of the continental shelf miles beneath the surface of the sea.

  Wallace’s line divided the ranges of human races, too. In January 1857, when the monsoons turned the rice fields of the coastal plains around Macassar into swamps and rotted all his specimens, a half-Dutch, half-Malay sea captain offered to take Wallace out to the Aru Islands, a tiny and legendary cluster of islands a thousand miles east, and bring him back six months later. As Wallace’s boat arrived at the island of Ke, off the south coast of New Guinea, his Malay crew were mobbed by a boatload of indigenous Papuans, “forty black, naked, mop-headed savages … intoxicated with joy and excitement.” Comparing the groups “side by side” he realized in “less than five minutes” that they “belonged to two of the most distinct and strongly marked races” on earth. “Had I been blind, I could have been certain that these islanders were not Malays,” he wrote. The two peoples, geographical neighb
ors, had descended from quite distinct ancestors who had lived and evolved on different landmasses. The beach at Ke marked the beginning of “a new world, inhabited by a strange people.” For six months, when he was not paralyzed by the ulcerated wounds from the bites of insects that he was convinced were taking their revenge on him, he roamed across these scattered islands with a team of Papuan boy hunters led and trained by Ali, observing the characteristics and behaviors of the different races closely, amazed by the gulf of difference.

  When he arrived back in Macassar, Wallace found two important letters among the pile that had accumulated in his seven-month absence. Finally someone had read his species paper. Bates wrote to congratulate him on his courage in going into print. “I was startled at first to see you already ripe for the enunciation of the theory,” he confessed; “the idea is like truth itself, so simple and obvious that those who read and understand it will be struck by its simplicity; and yet it is perfectly original.” A second letter, from Darwin, offered more muted praise. He told Wallace that he had been working on the species question for twenty years: “By your letter & even still more by your paper in Annals, a year or more ago, I can plainly see that we have thought much alike & to a certain extent have come to similar conclusions. In regard to the Paper in Annals, I agree to the truth of almost every word of your paper; & I daresay that you will agree with me that it is very rare to find oneself agreeing pretty closely with any theoretical paper; for it is lamentable how each man draws his own different conclusions from the very same fact.”