CHAPTER 8

The Mechanism Revealed

IN LATE SEPTEMBER 1857, Wallace sent a rambling letter to Darwin that has not survived intact. He must have reported the difficulties of life as a traveling naturalist, because in his reply Darwin offers sympathy and encouragement for his “laborious undertaking.” Wallace also seems to have alluded to his two-year-old paper, “On the Law Which Has Regulated the Introduction of New Species,” in the Annals and Magazine of Natural History and asked for feedback, providing additional data that he had gathered to support his hypothesis. From Darwin’s answers to this and other concerns, it is clear that Wallace elaborated on his belief in a former land connection between New Guinea and Australia in the distant past. Moreover, he wondered whether Darwin was planning to discuss the origin of humans in his upcoming book.¹

Wallace did not have time to wait for Darwin’s response. On November 19, he boarded a Dutch steamer bound for Amboyna (Ambon) and Ternate. The boat stopped first at Coupang (Kupang) in Timor and then at Banda, in the heart of the Spice Islands. Once again, Wallace was struck by the marked contrast of the archipelago’s islands, which differed in their vegetation despite the fact that all were volcanic in origin. East of Bali, they were almost barren, with scanty and scrubby plants, while the Moluccas, including Banda, Ke, and Aru, were covered with dense, verdant forests. He left Amboyna in early January 1858, but not before writing a long-overdue reply to Henry Bates’s letter congratulating him on his September 1855 Annals paper. “To persons who have not thought much on the subject, I fear my paper on the succession of species will not appear so clear as it does to you,” he told Bates. “That paper is, of course, only the announcement of the theory, not its development. I have prepared and written portions of an extensive work embracing the subject in all its bearings and endeavouring to prove what in the paper I have only indicated.”²

It was the first time that he had admitted to anyone his intention to publish a book on the origin of species, though in his species notebook he had mentioned this goal as early as 1856. In the book’s final chapter, he planned to disprove Sir Charles Lyell’s arguments against evolution.³ He confided to Bates that Darwin’s letter of May 1, 1857, had “much gratified” him. He felt that Darwin might “save him the trouble” of writing the second part of his hypothesis by proving that there was no difference between the origin of varieties and of species, or that Darwin might give him trouble by arriving at another conclusion. “Your collections and my own,” he told Bates, “will furnish valuable material to illustrate and prove the universal applicability of the hypothesis.”

Wallace reached the island of Ternate on January 8, 1858, his thirty-fifth birthday. Ternate was midway between Celebes and New Guinea and approximately 250 miles from each. Although only 65 square miles in extent, it had a past worthy of Timbuktu. Ternate and its tiny neighbor, Tidore, had been the center of the world’s spice trade when the Portuguese and Spanish arrived in the early sixteenth century. But by the time of Wallace’s visit, they were dismal backwaters under Dutch authority, with magnificent ruins the only evidence of their splendid past.

Wallace gave introductory letters to a man named Duivenboden, known as the King of Ternate because of his immense wealth and excellent connections in the region. Descended from an old expatriate Dutch family, Duivenboden owned half the town, many ships, and more than a hundred slaves. He had been educated in Europe and was well versed in science and literature, and yet, like the White Rajah of Sarawak, he preferred to preside over an insignificant kingdom in one of the remotest places on earth rather than live in the heart of European society as an ordinary citizen.⁴ The house that Duivenboden found for Wallace was a wreck, but Wallace saw potential in the solidity of its foundations and ample size. Its setting was perfect: there was a “wilderness” of fruit trees, with the market and beach only five minutes away, and towering over everything was the island’s four-thousand-foot-high volcano, with virgin forest extending up to the summit. But the feature that sealed the contract was the deep well, with its “inexhaustible supply” of cold water, a luxury in that part of the world. After minimal renovation and the purchase of a set of “cheap but elegant” bamboo furniture, Wallace established himself as “an inhabitant of the earthquake-tortured island of Ternate” for the next two and a half years.

In his first month on the island, Wallace added little to his collections. He was too busy fixing up his house and preparing for a visit to the zoologically unknown island of Gilolo (Halmahera), only ten miles east of Ternate’s harbor. He noted to Bates that “not a single insect has ever been collected there.” Before mailing the letter, he enclosed a memorandum with an estimate of the total number of distinct species of insects he had collected over three and a half years, which clearly demonstrated the archipelago’s impressive entomological diversity: 620 species of butterflies, 2,000 of moths, 3,700 of beetles, 750 of bees and wasps, 660 of flies, 500 of bugs and cicadas, 160 of locusts, 110 of dragonflies, and 40 of earwigs, totaling 8,540 species (the number of specimens is unrecorded).⁵

Wallace left for Gilolo sometime in late January or early February on a boat owned by a Dutchman, captained by a Chinese, and rowed by a crew of Papuan slaves—a human diversity that did not escape his notice. They landed at the village of Sedingole, in the center of the island. Gilolo, a miniaturized version of Celebes, was shaped like a distorted starfish (minus one appendage), with four mountainous, densely forested arms. Only the coast was settled; the interior remained as wild as in the days before the Dutch arrived. After two unproductive days in Sedingole, Wallace set sail for Dodinga, navigating smoothly between small islands along the coast and reaching the village at dawn the next day. Dodinga, located on a narrow isthmus separating the north and south peninsulas, was guarded by a Dutch corporal and four Javanese soldiers, who occupied a small ancient Portuguese fort that was in shambles from having been battered by earthquakes. The luxuriant forest, brightened by masses of large scarlet flowers, promised zoological treasures, but Wallace was unable to do much because of an attack of malaria. On March 1, he returned to Ternate with a small number of insects and birds to await the return of Duivenboden’s schooner from Macassar, which would take him to New Guinea, the land of the bird of paradise.

From January 8 until March 1, his documentation is scanty: a “fortnight” in Ternate and “a month” in Gilolo; a list of insects and birds in his insect and bird registries; a letter to Henry Bates and another to Henry’s brother, Frederick; a few notes in his private journal about the islands, his difficulties, and the behavioral and physical characteristics of the people. And yet at some time during those two months, he found the time to pen an essay that opened up a new chapter in the history of science.

For reasons that will soon become clear, Wallace omitted from his highly acclaimed travel narrative The Malay Archipelago, published in 1869, not only any allusion to that seminal essay but also any credit for the independent discovery of the theory of natural selection. Ambiguities still surround the composition of the paper. His journals mention nothing about it, the original was lost after its publication in England, and no drafts were saved. It was allegedly sent from Ternate in February, but his insect, bird, and mammal registries all indicate that he was on the island of Gilolo, not Ternate, in February 1858, an incongruity that Wallace never clarified and that remains a minor mystery.⁶ Eventually, prodded by friends, he told a tale that was full of romance and drama.⁷

According to his recollections, he was lying in bed one day in his cottage in Ternate, suffering from a “rather severe” attack of malaria. Never far from his mind, even in such trying moments, was the main impetus for traveling to the ends of the earth, the problem that had obsessed him for a decade. Up to this point, he was convinced that changes in species had taken place by natural succession and common descent, either slowly or rapidly, depending on conditions. Almost fifty years later, in My Life, his autobiography, he reconstructed his thinking at the time: “The problem then was not only how and why do species change, but how and why do they change into new and well-defined species, distinguished from each other in so many ways; why and how do they become so exactly adapted to distinct modes of life; and why do all the intermediate grades die out (as geology shows they have died out) and leave only clearly defined and well-marked species, genera, and higher groups of animals?”⁸

Wallace had not limited his thinking to animal species. His examinations of plants led to similar conclusions. He was also acutely aware of human diversity—mental, moral, and physical. He had not exempted the human species from natural law; this seems clear from what we know of his September 1857 letter to Darwin and from the tenor of “A New Kind of Baby,” a paper on the orangutan that had been published in the November 22, 1856, issue of Chambers’s Journal. With such thoughts tormenting him—and in a “cold fit,” wrapped up in a blanket despite an ambient temperature of eighty-eight degrees Fahrenheit—he stated that he somehow was led to think of the “positive checks” described by Thomas Malthus, whose work he had not recalled until that moment. Malthusian checks on human population growth—war, famine, disease, infertility—also applied to animal populations. In the space of two hours that had elapsed between the onset of chills and their subsidence in a pool of sweat, Wallace said that he had devised the entire theory of natural selection, which, despite physical exhaustion, he sketched out that same evening. It was a spark of inspiration that brought together years of experience and contemplation. Over the next two evenings, he wrote the theory out in full.

Wallace called his essay “On the Tendency of Varieties to Depart Indefinitely from the Original Type; Instability of Varieties Supposed to Prove the Permanent Distinctness of Species,” an allusion to both Lamarck and Lyell.⁹ In his opening remarks he states that “there is a general principle in nature which will cause many varieties to survive the parent species, and to give rise to successive variations departing further and further from the original type and which also produces, in domesticated animals, the tendency of varieties to return to the parent form.” He interweaves two major themes: divergence from a common ancestor, or “antitype,” the unusual word he ascribes to the progenitor; and survival of the fittest, leading to the formation of new species. His purpose is to strike at the very foundation of the notion of the “fixity” of species. He already had introduced his principle of divergence and descent with modification—the Sarawak Law—in “On the Law Which Has Regulated the Introduction of New Species” and in “Attempts at a Natural Arrangement of Birds,” in which he applied the principle. His revelation was the mechanism, the long-sought-after causation, which came to him in a flash of insight.

As in his 1855 essay, Wallace constructed his argument inductively, elaborating on commonly known facts. The life of wild animals is a struggle for existence, he reminded his audience, and in that struggle animals are concerned with two things: self-preservation and the survival of their infant offspring. The survival not only of the individual but of the entire species depends on the successful procurement of food during hard times and the avoidance of enemies; otherwise, large numbers of animals will die, and the species will verge on extinction. “The struggle for existence” was not a novel phrase. Malthus, Robert Owen, and Lyell had used it. So had the Swiss botanist Alphonse de Candolle. Malthus had applied the term to human populations; Lyell, to animal populations; and Candolle, to plant populations. Wallace extended it much further. The struggle for existence explained what before seemed inexplicable: why some species were abundant and others, closely allied, were rare. The “law of population” and not fecundity, he said, determined the relative abundance or rarity of a species. Any animal, large or small, would increase in a geometric ratio if permitted. By means of a simple calculation, it could be shown that one pair of birds would generate 10 million offspring in fifteen years. Malthus had demonstrated this phenomenon in human populations, but populations in the animal world were generally stable. While hunting birds of paradise, for example, Wallace had noted a superabundance of immature males and relatively few adults: “It is evident, therefore, that each year an immense number of birds must perish—as many in fact as are born. It would therefore appear that, as far as the continuance of the species and keeping up the average number of individuals concerned, large broods are superfluous.”

What controlled population levels? Availability of food, but also predation, disease, and impaired fertility. If food supplies increased arithmetically while animal populations increased geometrically, animals would quickly outstrip their food supply. As long as the environment remained physically unchanged, the numbers of its animal population could not increase materially. The numbers dying annually were immense, and those that died usually were the weakest—the very young, the very old, the diseased—while those that survived were the most healthy and vigorous. In the struggle for existence, the weakest and most defective must die.

At this point, Wallace introduced the concept of “utility” of variations. Any variation, however slight, would affect the population either positively or adversely. All varieties fell into two classes: those that remained in the minority under stable conditions and those that achieved numerical superiority over the parent population. A drought, a plague of locusts, a new predator—in short, any change that made conditions difficult for a species—would tax its “utmost power” to avoid extermination. Clearly, the least numerous and most “feebly organised” variety would suffer first and become extinct if the pressure was great enough. If the parent species was less fit in any way, the stronger variety would surpass it in numbers.

Once a variety replaced a species, it could never return to the “original” form. This new, improved, and populous race might in time give rise to new varieties that exhibited “several diverging modifications of form,” any of which, if improving fitness, could become dominant under the right conditions. “Here, then,” Wallace wrote, “we have progression and continued divergence deduced from the general laws which regulate the existence of animals in a state of nature.” But he did not advocate an inevitable forward progression. If conditions changed again, the parent form and the other failed varieties—assuming they still existed—might suddenly flourish at the expense of the formerly fittest variety, no longer superior and now in danger of extinction.

Domesticated species were generally inferior forms, sustained and propagated artificially; in a state of nature, most of these animals would die. If they survived in the wild, their descendants would tend to “return” toward the fitter and better adapted wild form. Lamarck’s hypothesis—that acquired characteristics are passed on to one’s progeny—was unnecessary. In the case of the giraffe, for instance, those of its ancestors that had longer necks survived in times when food was scarce because of their ability to reach the loftiest foliage; thus their offspring were more numerous, while the competing, shorter-necked variety gradually became extinct.

Wallace’s principle had wide applications. As Bates had predicted, new avenues of study suddenly opened up for scientists. As Wallace noted:

Even the peculiar colours of many animals, especially insects, so closely resembling the soil or the leaves or the trunks on which they habitually reside, are explained on the same principle. An origin such as is here advocated will also agree with the peculiar character of the modifications of form and structure which obtain in organized beings—the many lines of divergence from a central type, the increasing efficiency and power of a particular organ through a succession of allied species, and the remarkable persistence of unimportant parts such as colour, texture of plumage and hair, form of horns or crests, through a series of species differing considerably in more essential characters.

In amassing his collections, Wallace had proved to himself that variation was a fact of nature. Now he held that those variations tended to be inherited—though he did not use that term—and that the most successful variations proliferated, while those that were less successful tended to lead to extinction, a dynamic process constantly regulated by checks and balances in the surrounding environment. Changes were not sudden (as Lamarck would have it) but gradual, occurring over immense periods of time and progressing “by minute steps in various directions.” His theory agreed with all the phenomena of life: extinction, derivation of present-day species from past species, physical form, instincts, and habits. He had discovered a true natural system, one without a predetermined balance, teleology, or divine plan.

Once Wallace had written his essay in its final form, he decided to send it to Darwin, who he hoped would find the ideas in it helpful in his own work on the origin of species. In the accompanying letter—which has been lost, though he recounts the gist of it in his autobiography—he asked Darwin to show the essay to Lyell for his opinion if he thought it “sufficiently important.”¹⁰ It was a bold request—one that makes sense only if Wallace already knew of their friendship and was aware of Lyell’s interest in his theoretical work. It is therefore likely that the mail steamer from Singapore that arrived in Ternate on March 9 carried Darwin’s response to Wallace’s letter of the previous September.¹¹ In it Darwin writes, “You say that you have been somewhat surprised at no notice having been taken of your paper in the Annals. I cannot say that I am; for so very few naturalists care for anything beyond the mere description of species. But you must not suppose that your paper had not been attended to: two very good men, Sir C Lyell and Mr E Blyth at Calcutta, specially called my attention to it. … [T]hough agreeing with you on your conclusions in the paper, I believe I go much further than you; but it is too long a subject to enter on my speculative notions.”¹²

What Wallace did not know, and what he could not have known at the time, was that his discovery of the theory of natural selection marked another turning point in his life—but for reasons that (he later alleged, with characteristic understatement) had nothing to do with Darwin. In My Life, he remarks that his solution to the origin of species caused him to branch out into a different intellectual direction. Before his discovery, he had devoted his time to describing, cataloguing, and working out the distribution of his birds and insects. If he had not hit on the mechanism of evolution, he believed, he would have spent “the best years” of his life in what he came to consider “comparatively profitless work.” His new discovery “swept all this away,” and he decided to let others complete the tedious task of identifying and naming his specimens. He could now dedicate himself to “the great generalizations” that his labors and that of others had made possible.¹³

Wallace arrived in Dorey, on New Guinea, on April 10. He had left Ternate on March 25 on a prau belonging to his friend Duivenboden, accompanied by Ali and three other servants. As the rugged mountains of the New Guinea coast loomed ahead, he gazed with intense interest at the place he had longed to visit, the succeeding ridges of the interior, “where the foot of civilized man had never trod.”¹⁴ Dorey itself, however, had seen previous European visitors. The French naturalist René-Primevère Lesson had stopped there forty years earlier, and now German missionaries were headquartered in the town. Wallace presented a letter from the Dutch governor to one of the missionaries, who facilitated his contact with the native chief. The chief built him a hut facing the sea.

Wallace remained for ten days in this impoverished village, ingratiating himself with the chief by offering him gifts and promising payment for any specimens—particularly of the vaunted birds of paradise—that his people could provide, but even with these incentives they brought him no birds of paradise and very little of anything else. On May 5, a Dutch steamer anchored off the beach near his hut, and the little luck he had enjoyed came to an end. The steamer carried the prince of Tidore, son of the sultan, and his retinue, who monopolized both food and wildlife. The prince, who remained on board his vessel and sent everyone else out as his emissaries, had come to Dorey to acquire the skins of birds of paradise, ruining Wallace’s arrangements (however unrewarding) with the locals. Even worse, all fish and vegetables were sold to the Tidoreans, leaving Wallace and his men with almost nothing to eat. The only benefit the ship brought was its German doctor, whose services Wallace badly needed. After clambering over some fallen trunks and branches, he had cut his ankle, which then swelled and ulcerated. When the ulcer healed, the Achilles tendon just above its insertion on the heel became inflamed. The doctor advised poulticing the ankle for several days, which only made the inflammation and swelling worse. The area then had to be leeched and covered with ointments and more poultices for several weeks, driving Wallace to the brink of despair. Once again, he was languishing in a hut in a remote part of the world that he might never be able to revisit, forfeiting who knew how many new species a day because of a simple mishap. A month would pass before Wallace dared venture out. Not long after recovering from his ankle ulcer, he was afflicted with fever and a severe soreness of his mouth, tongue, and gums, which prevented him taking anything but liquid meals. By turns, everyone in his party became ill with malaria or dysentery. One of his men—a quiet but reliable eighteen-year-old named Jumaat, from Boutong, an island south of Celebes—developed a fever, lingered for a couple of weeks, and died in late June despite Wallace’s ministrations with the limited stock of medicines he had at his disposal. A Muslim, like all of Wallace’s assistants, Jumaat was buried in the Islamic fashion, enshrouded in cotton cloth that Wallace provided for the occasion.

The trip to New Guinea was a disaster for Wallace, culminating in the tragic death of one of his assistants. He did not see a single bird of paradise, the sole reason for having risked his life and the lives of his men. He caught nothing rare or novel. The most abundant insects were ants, which descended on his hut with a vengeance, carrying off specimens as he worked and even tearing the labels off the cards the specimens were attached to. Flies attacked his bird skins, laying masses of sticky eggs that hatched ravenous maggots. Wallace sent a summary of his visit to Norton Shaw at the Royal Geographical Society, suggesting that it contained nothing worthy of insertion in the society’s transactions, but Shaw and Sir Roderick Murchison disagreed. “Mr. Wallace was, as he himself truly observes, the sole European inhabitant, and we may safely add, the sole civilised being, on New Guinea for three months,” Murchison said in his anniversary address of 1859. “The researches of this skillful naturalist were necessarily confined to a small portion of the island, Doree. … Mr. Wallace’s paper supplies us with by far the best account of the geology and geography of the place he visited, while other Societies have properly received his contributions to botany and zoology.”¹⁵

Wallace returned to Ternate in mid-August, grateful to experience again the simple joys of life—milk in his tea and coffee and variety in his diet. He found five months’ worth of mail and journals awaiting him, including news of the safe arrival of his Aru collections and the “admiration they excited.” The news infused in him a new spirit of determination. More cheering was the £1,000 that these collections had earned him. “This makes me hope I may soon realise enough to live upon and carry out my long cherished plans of a country life in Old England,” he wrote to his “dear old” mother.¹⁶ Apparently the world wanted more, as though he were a machine manufacturing new species. Samuel Stevens received the brunt of his anger. “You ask me if I go out to collect at night; certainly not,” Wallace wrote.

[A] man who works, with hardly half an hour’s intermission, from 6 A.M. until 6 P.M., four or five of the hottest hours being spent entirely out of doors, is very glad to spend his evenings with a book (if he has one) and a cup of coffee and be in bed soon after 8 o’clock. Night work may be very well for amateurs, but not for the man who works twelve hours every day at his collection. … You and Dr Gray seem to imagine that I neglect the mammals, or I should send more specimens, but you do not know how difficult it is to get them: at Dorey I could not get a single specimen.¹⁷

But the news that Wallace hoped to hear most of all had not arrived: there was nothing from Darwin or Lyell. He had mailed his essay to Darwin in early March; the earliest he could have expected a response was twenty weeks later, toward the end of July. Although he must have been disappointed, he was probably not surprised; no important paper he had written thus far had elicited an immediate reaction from anyone.

In mid-September, he made a second expedition to Gilolo, which was cut short when he discovered that his path to the slopes of the distant summits, reputed to be teeming with birds, was barred by impassable grass eight to ten feet high. He next prepared for a journey to Batchian, 150 miles to the south. The unpacking from one unsuccessful voyage; the repacking for another trip, which might be equally unfruitful; and the frustrating search for a boat and crew tried his patience. As Wallace occupied himself with these annoyances, the Dutch mail steamer arrived with more mail from home. This time, his packet included two letters, one from Darwin and the other, oddly, from Joseph Hooker, one of England’s finest botanists and a man he knew only by reputation. The letters from Darwin and Hooker told an extraordinary story. By a coincidence almost beyond belief, Wallace’s essay outlined the same doctrine that Darwin had discovered and had been laboring over for almost two decades but had not yet published!¹⁸

The Darwinian theory, as it is known today, is a two-part theory, embodied simply and elegantly in Wallace’s essay: evolution from a common origin through the agency of natural selection. The great power of the Darwin–Wallace theory is the unification of two independent ideas—the survival of the fittest and the common origin and divergence of species—to explain, better than any other previous theory, the distribution and diversity of life on the planet. Yet how did two men, working on opposite sides of the globe, arrive at similar conclusions independently and virtually simultaneously?

Not long after returning from the Galápagos in 1836, Darwin became convinced of the probability of evolution, but the theory he originally conceived was not the one he published some twenty years later. In the late 1830s, he believed that gradual changes in the movements of the earth’s crust somehow encouraged species to vary, become modified, and evolve into different species. As it had for Wallace, Lyell’s uniformitarian doctrine provided Darwin with a scientific framework for examining the organic world. But an intensive investigation of barnacles, which occupied eight wearying years of his life, altered his views on the cause of variations, though he confessed that he doubted whether the work was worth the amount of time he had devoted to their study. “[It] was … evident that neither the action of the surrounding conditions, nor the will of the organisms … could account for the innumerable cases in which organisms of every kind are beautifully adapted to their habits of life,” he wrote in his autobiography.¹⁹ Barnacles taught Darwin what Wallace would learn from his experiences as a field biologist: that variations occurred naturally and spontaneously. Variations were the material on which natural selection acted. Moreover, Darwin concluded that variations appeared as a natural outcome of sexual relations. Internal factors (which were not yet defined, for genetic theory lay in the future) and sex, not external factors, played a fundamental role in the development of variation. As Darwin scholar Janet Browne has noted, this was one of the great intellectual achievements predating the publication of The Origin of Species.²⁰

In 1842, when the nineteen-year-old Wallace was poring over William Swainson’s Treatise on the Geography and Classification of Animals, Darwin sketched out in thirty-five pages his theory of natural selection, a term he had invented to describe the outcome of the struggle for existence and the natural process equivalent to the artificial selection practiced on domestic animals and plants. Natural selection was an idea that had come to him in 1838, after reading Malthus’s Essay on the Principle of Population, which would also play a seminal role in Wallace’s thinking. In the summer of 1844, he expanded the sketch to 230 pages, which he copied out in more legible form. Hooker was the only man who had read this document, which was then put aside, with instructions to Darwin’s wife, Emma, to publish it only if he died before he could complete a larger work. For the next fourteen years, he continued to conduct his research painstakingly and methodically, concocting “little” experiments to answer questions that sometimes seemed to touch tangentially on the subject of the origin of species—for example, testing his hypothesis that bees are necessary for both the self-fertilization and the crossing of kidney beans—and amassing a mountain of facts from his contacts with naturalists on nearly every continent, who provided him with specimens and data on request.²¹ His object, he wrote to his cousin William Darwin Fox in March 1855, was “to view all facts that I can master … in Nat[ural] History, (as on geograph[ic] distribution, paleontology, classification, Hybridism, domestic animals & plants &c &c &c) to see how far they favour or are opposed to the notion that wild species are mutable or immutable: I mean with my utmost power to give all arguments & facts on both sides.”²²

As for the principle of divergence, the other critical element in evolutionary theory, scholars have suggested that Darwin already had alluded to the principle as early as 1837, for in one of his early notebooks he had used the analogy of a tree of life to describe the concept of gradual evolution (hence Darwin’s reaction—“nothing very new”—when he read Wallace’s “On the Law Which Has Regulated the Introduction of New Species”).²³ But not until August 1857 did he use the term itself in a letter to Hooker. One month later, he sent a letter to the Harvard botanist Asa Gray outlining his theory of natural selection and the principle of divergence as it applied to the theory. “Each new variety or species when formed will generally take the place of, and so exterminate its less well-fitted parent,” Darwin told Gray. “This I believe to be the origin of the classification or arrangement of all organic beings at all times. These always seem to branch and sub-branch like a tree from a common trunk.”²⁴

Both Wallace and Darwin were profoundly influenced by the same two men, Lyell and Malthus, and had access to a similar body of data—a fact that is no coincidence. But they approached the problem from opposite directions. Wallace discovered his principle of divergence before discovering natural selection, the mechanism behind that divergence. Darwin discovered natural selection first and joined it to his principle of divergence, the result of natural selection, more than a decade later. Wallace arrived at his conclusion from studies of organisms in their natural habitats; Darwin did so from studies of domesticated animals, barnacles, and plants. As the years progressed, Darwin’s and Wallace’s views would converge until the critical day in June 1858. Until that point, neither man fully grasped that each was about to collide with the other.

On June 18, 1858, Darwin made the following annotation in one of his journals: “interrupted by letter from A R Wallace.” Clearly it was one of the lowest points in his life. He was so upset by what Wallace had sent him that the obsessive documentation of his daily activities and ruminations came to a sudden halt.²⁵ After reading Wallace’s “On the Tendency of Varieties to Depart Indefinitely from the Original Type,” he was faced with a serious dilemma—one that Lyell had predicted and that was now his to solve. His emotional turmoil is reflected in a letter he sent to Lyell that day:

My dear Lyell,

[S]ome year or so ago you recommended me to read a paper by Wallace in the Annals, which had interested you, and as I was writing to him, I knew this would please him much, so I told him. He 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. You said this, when I explained to you very briefly my views on “Natural Selection” depending upon the struggle for existence. I never saw a more striking coincidence; if Wallace had my MS sketch written out in 1842 [sic] he could not have made a better short abstract! Even his terms now stand as heads of my chapters. Please return me the MS, 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 will be smashed, though my book, if it will ever have value, will not be deteriorated; as all the labour consists in the application of the theory.²⁶

Lyell did not answer at once. One week later, an apparently distraught Darwin wrote another letter:

My dear Lyell,
I am very sorry to trouble you, busy as you are, in so merely personal an affair; but if you will give me your deliberate opinion, you will do me as great a service as ever man did, for I have entire confidence in your judgment and honour. … There is nothing in Wallace’s sketch which is not written out much fuller in my sketch, copied out in 1844, and read by Hooker some dozen years ago [sic]. About a year ago I sent a short sketch, of which I have a copy, of my views … to Asa Gray, so that I could most truly say and prove that I take nothing from Wallace. I should be extremely glad now to publish a sketch of my general views in about a dozen pages or so; but I cannot persuade myself that I can do so honourably. Wallace says nothing about publication, and I enclose his letter. But as I had not intended to publish any sketch, can I do so honourably because Wallace has sent me an outline of his doctrine? I would far rather burn my whole book, than that he or any other man should think that I had behaved in a paltry spirit. Do you not think his having sent me this sketch ties my hands? … If I could honourably publish I would state that I was induced now to publish a sketch … from Wallace having sent me an outline of his conclusions. We differ only [in] that I was led to my views from what artificial selection has done for domestic animals. … This is a trumpery affair to trouble you with, but you cannot tell me how much I should be obliged for your advice. By the way, would you object to send this and your answer to Hooker to be forwarded to me? for then I shall have the opinion of my two best and kindest friends.²⁷

Darwin sent one final thought in a postscript to Lyell: “It seems hard on me that I should be thus compelled to lose my priority of many years’ standing, but I cannot feel at all sure that this alters the justice of the case.” Calling him a “first-rate Lord Chancellor,” Darwin appealed to Lyell to resolve the problem.

Lyell followed Darwin’s instructions by sending Wallace’s paper and letters, along with Darwin’s responses, to Hooker. Hooker, eight years younger than Darwin, was probably Darwin’s closest scientific friend, and Darwin admired his keen intellect and blunt, constructive opinions. He could depend on Hooker’s honesty, especially in the evaluation of his work. When Darwin had completed his manuscript on evolution in 1844, he suggested that Lyell edit his work; a decade later, he changed his mind, amending his will in order to assign the task of editing to Hooker.²⁸

An emergency meeting of the Linnean Society—which, along with the Zoological and Entomological Societies, was among London’s chief scientific conclaves—provided Hooker and Lyell with an opportunity to help Darwin out of his bind. The scientific societies generally disbanded for the summer holidays, not meeting again until October or November, but the death on June 10 of Robert Brown, the most eminent English botanist of the time, left a vacancy on the Linnean Society’s board that had to be filled within three months, according to its bylaws. Out of respect to Brown, the regular June meeting had been postponed to July 1. On June 29, Hooker pressured Darwin to get some material—any material—together to be presented at the society in three days.²⁹

In the meantime, not long after Darwin mailed his anguished deliberations, his infant son, Charles, developed scarlet fever and died; both his wife and his daughter were ill with diphtheria. Darwin responded to Hooker that evening:

I have just read your letter and see you want papers at once. I am quite prostrated & can do nothing but I send Wallace & my abstract of abstract of letter to Asa Gray, which gives most imperfectly only the means of change & does not touch on reasons believing that species do change. I daresay all is too late. I hardly care about it.—But you are too generous to sacrifice so much time & kindness.—It is most generous, most kind. I send sketch of 1844 solely that you may see by your own handwriting that you did read it.—I really cannot bear to look at it. Do not waste much time. It is miserable in me to care at all about priority.³⁰

Some thirty people, less than 10 percent of the society’s membership, attended the July 1 meeting. Darwin, still grieving over the death of his son, remained at home. Lyell and Hooker railroaded the papers by Darwin and Wallace onto the agenda, displacing the papers of other men who had been scheduled to make presentations.³¹ One of those was the botanist George Bentham, who felt “severe pain and disappointment” at having been preempted.³² The secretary of the society, John Joseph (J. J.) Bennett, read an introductory letter from Hooker and Lyell explaining the Darwin–Wallace conjunction, which began:

These gentleman, having, independently and unknown to one another, conceived the same very ingenious theory to account for the appearance and perpetuation of varieties and of specific forms on our planet, may both fairly claim the merit of being original thinkers in this important line of inquiry; but neither of them having published his views, though Mr. Darwin has for many years been repeatedly urged by us to do so, … we think it would best promote the interests of science that a selection from them should be laid before the Linnean Society.³³

The papers were read—by George Busk, the society’s undersecretary—in the order of their dates of composition: the first was Darwin’s abbreviated abstract of his 230-page essay from 1844; the second was the “abstract of abstract” of his letter to Gray of September 5, 1857. The last offering was Wallace’s “On the Tendency of Varieties to Depart Indefinitely from the Original Type.” Hooker and Lyell reported that they had explained to Darwin “that we are not solely considering the relative claims of priority of himself and his friend, but the interests of science generally.”

July 1, 1858, was the true birth of the modern theory of evolution, parented by both Darwin and Wallace. But the audience was somewhat baffled, if not overwhelmed, by the presentation. Hooker later said that Lyell’s tacit approval of the papers as well as his own presence “as his lieutenant in the affair” must have “overawed” the fellows, who might otherwise have “flown out” against the doctrine. The papers generated little response and virtually no discussion. Bentham, whose article “On the Species and Genera of Plants, Considered with Reference to Their Practical Application to Systematic Botany” had illustrated facts and observations related to the “fixity” of species, was stunned and decided not to read his paper. Years later, he told Francis Darwin that he had realized that he would be forced, “however reluctantly,” to give up his “long-cherished convictions.”³⁴ At year’s end, Thomas Bell, the president of the society, pronounced that 1858 was not “marked by any of those striking discoveries which at once revolutionize … the department of science on which they bear.”³⁵ Not even Thomas Huxley fully grasped the significance of Wallace’s contribution; he perceived the event through Darwinian eyes only. “Wallace’s impetus seems to have [got?] Darwin going in earnest,” Huxley told Hooker, “and I am rejoiced to hear we shall learn his views in full; at last I look forward to a great revolution being effected. Depend upon it in Natural History, as in everything else, when the English mind fully determines to work a thing out it will do it better than any other.”³⁶

But for Darwin, the joint presentation of the papers was a boon. Lyell finally had succeeded in bringing his views, imperfect as they were, into the light of day. Darwin was “much more than satisfied” at what had taken place, for he had thought that his letter to Gray would be read as an appendix to Wallace’s paper, not second in order of presentation. He had begun to compose a letter to Wallace in which he relinquished all priority, but changed his mind when he learned of Lyell and Hooker’s “extraordinary kindness” in the management of the affair.³⁷ The public support that Lyell and Hooker gave to his views convinced Darwin to accelerate the timetable for completing his book. He abandoned his original work, “Natural Selection,” in favor of an abstracted version, which he set out to compose at an unprecedented pace, almost certainly imagining an equally eager Wallace nearing completion of his own species book. “It is really impossible to do justice to the subject,” Darwin wrote to Lyell that July, “except by giving facts on which each conclusion is grounded & that will of course be absolutely impossible. … I look at this as so very important that I am almost glad of Wallace’s paper for having led to this.”³⁸

Not all historians of science are satisfied with this account of a famous historical conjuncture. John Langdon Brooks has cast a less flattering light on the events of 1858. He believes that Darwin behaved in an underhanded manner to secure his place in history, outmaneuvering Wallace, who should be recognized as the first person to announce a complete theory of evolution. Brooks’s investigation focuses on a sliver of time that Darwin specialists have elected to pass over. What really happened to Wallace’s paper, he asks, after it was mailed from Ternate in March 1858? Brooks assiduously works out the elaborate journey of Wallace’s essay to Down House and concludes that it could have arrived in England as early as May 18. (H. L. McKinney provides evidence that a letter to Henry Bates’s brother, Frederick, dated March 2, 1858, but presumably mailed on the same day as the essay to Darwin, arrived in Leicester on June 3.)³⁹ Thus Darwin possessed Wallace’s essay for at least two weeks—and perhaps for as long as a month—prior to his notation of its receipt in his private journal and the letter to Lyell. During this time period, Brooks boldly asserts, Darwin engaged in a bit of intellectual piracy, revising his notions about natural selection and divergence after reexamining Wallace’s Sarawak Law paper, “On the Law Which Has Regulated the Introduction of New Species,” and studying the new essay. These revisions, eventually embodied in the later chapters of The Origin of Species, resemble Wallace’s conceptions more than his own previous sketchy ideas, which did not make as striking a connection among extinction, intermediate forms, and the natural system of classification.⁴⁰ That resemblance, he claims, is greater than Darwin scholars have acknowledged, and he spends a good portion of his book comparing sections of the Origin and Wallace’s essays to substantiate his claim of intellectual theft. Without Wallace’s two papers, according to Brooks, Darwin could not have completed the Origin. Darwin not only plagiarized Wallace but never gave him proper credit for his critical contributions in any edition of the Origin or in his autobiography.

Arnold Brackman, who shares Brooks’s conviction, is even less sanguine about the outcome of the July 1, 1858, meeting of the Linnean Society. Brackman accuses Darwin, Hooker, and Lyell of conspiring to rob Wallace of his rightful claim to priority. It is a classic tale of class power, he says, one more example of an elite group of men trampling a lower-class rival.⁴¹ Lost letters, a missing manuscript, pirated doctrines, behind-the-scenes maneuvering, and mea culpa letters to the offended party all lend themselves to assertions of foul play—Wallace and Darwin à la Mozart and Salieri.

But such views oversimplify the events of 1858 and presume that the participants possessed a greater knowledge of the future than they actually had. Despite their eloquent advocacy, Brooks and Brackman have failed to convince leading scholars that Darwin plagiarized Wallace, though many have criticized Darwin (in retrospect) for inadequately referencing Wallace’s work in future editions of the Origin. In their eagerness to vilify Darwin, Brooks and Brackman barely acknowledge the breadth and intricacy of Darwin’s research, which is amply documented in his private journals, notebooks, and vast correspondence—the last comprising several volumes that have been analyzed, annotated, and published by historians at Cambridge University. Even a cursory examination of these documents will impress all but the most hardened skeptics with the magnitude of Darwin’s endeavors and reveal the hyperbole of Brooks’s and Brackman’s claims. As the editors of Darwin’s correspondence justly note, “the impressive scope of Darwin’s practical researches, demonstrating a desire to examine fully the consequences of his theories, provided the basis for the eventual presentation of natural selection as a theory firmly founded on observation and experiment.”⁴² Moreover, Brackman disparages the character of two honorable and highly respected scientists who sincerely believed that they were serving the interest of science in general and that of their friend in particular. There is little evidence that they bore any malice toward Wallace at the time. And although Wallace’s class status affected the trajectory of his career, it played no role in this specific episode. Had Hooker and Lyell—reluctant rebels against ecclesiastical or political authority—foreseen that their actions would eventually unleash a firestorm of controversy, they might have been far less enthusiastic in their support of “an important line of [scientific] inquiry” than they appeared to be in July 1858.

Nevertheless, Darwin procrastinated in publicizing his theory, a lapse that nearly cost him enduring fame. Whatever the reason for this delay—failure of nerve, a passion for perfection, periodic debilitating illness—it was not until the unexpected appearance of Wallace’s essay that the issue of priority suddenly reared its ugly head. Devastated by the communiqué from Wallace and distracted by a tragedy at home, he turned to his friends for help. The two men came through in a way more subtle than sinister; by presenting notes and papers chronologically, they implied that Wallace bolstered Darwin. Thus Wallace—from the perspective of history—was relegated to a secondary role in the greatest scientific revolution of modern times.

A more serious claim—and one that is harder to dismiss—is that Wallace and Darwin did not elaborate the same theory of natural selection, that their independent conceptions differed fundamentally. First, applying the terminology of the evolutionary biologist Ernst Mayr, Wallace’s analysis appears to be a study of population ecology; that is, he seems to suggest that natural selection acted at the level of varieties and species, with the most unfit groups perishing. Darwin, though, believed that the struggle for existence occurred at the individual level, with the most fit winning the battle of life single-handedly and becoming better adapted to the surrounding conditions.⁴³ The confusion about Wallace’s conception has arisen, in part, because of his terminology, which was expressed in a hastily written paper. At times, he used the terms “variety” and “variant individuals” interchangeably. Thus it is unclear if in 1858 he considered competition among individuals to be as important as competition among subpopulations in a species.⁴⁴ Second, according to Wallace scholar Malcolm Kottler, Wallace and Darwin did not mean the same thing when they described their principles of divergence. Wallace perceived divergence as mainly a linear process. At the beginning, for example, there is species A, which evolves into a1-a2-a3 … a10, species a10 being quite distinct from A. Darwin, however, recognized both linear divergence and branching divergence. In branching divergence, species A evolves into species a10 as well as species m10, m10 being as distinct from A as it is from a10. Darwin depicted this process in the Origin a year later in his famous schema of the probable effects of natural selection through divergence of character and extinction on the descendants of a common ancestor.⁴⁵

But, as has already been noted, Wallace did acknowledge the concept of branching divergence, in both “On the Law Which Has Regulated the Introduction of New Species” and “Attempts at a Natural Arrangement of Birds.” The problem is that in 1858 Wallace had not had time to elaborate fully his ideas on evolution: his publications were meant to foreshadow a future, better-documented work to be entitled “On the Law of Organic Change.” Moreover, the point as to whether the differences between Wallace and Darwin are historically important is moot: in June 1858, the similarities and not the differences alarmed Darwin—and, knowing what transpired afterward, Darwin’s perception is the crucial factor here.

And how did Wallace react to this improbable chain of events? If he was as devastated as Darwin, he never revealed his anguish, either in his journals or in letters to his family and friends. His response was measured and professional, consonant with the tone of the letters from two of England’s best-known and respected scientists, Hooker and Darwin. Wallace wrote to Hooker from Ternate on October 6, 1858:

Allow me in the first place sincerely to thank yourself and Sir Charles Lyell for your kind offices on this occasion, and to assure you of the gratification afforded me both by the course you have pursued, and the favourable opinions of my essay which you so kindly expressed. I cannot but consider myself a favoured party in this matter, because it has hitherto been too much the practice in cases of this sort to impute all merit to the first discoverer of a new fact or a new theory, and little or none to any other party who may, quite independently, have arrived at the same result a few years or a few hours later. … [I]t is evident that the time has now arrived when these and similar views will be promulgated and must be fairly discussed.

Wallace considered it a “most fortunate circumstance” that he had initiated a correspondence with Darwin on the subject of “varieties” and thus caused Darwin to move up the publication date of part of his researches. He had no doubt that Darwin’s views were more complete than his own and secured for Darwin the right to claim priority: “It would have caused me much pain and regret had Mr. Darwin’s excess of generosity led him to make public my paper unaccompanied by his own.”⁴⁶ He also replied to Darwin in a letter that has also regrettably not been preserved but that was undoubtedly written in the same spirit.

On the same day that Wallace wrote to Darwin and Hooker, he sent a letter to his mother with the news, noting that he was “highly gratified” to have received communications from Darwin and Hooker and flattered that Lyell had thought highly enough of his paper to allow its immediate presentation at the Linnean Society. “This assures me the acquaintance of these eminent men on my return home,” he told her.⁴⁷ To Stevens he exulted, “An essay on varieties which I sent to Mr. Darwin has been read to the Linnean Soc[iety] by Dr. Hooker and Sir C. Lyell on account of an extraordinary coincidence with some views of Mr. Darwin, being written but not yet published, and which were also read at the same meeting. If these are published I dare say that [the Society] will let you have a dozen copies for me. If so, send me three, and of the remainder send one to Bates, Spruce and any other of my friends who may be interested in the matter who do not attend the Linnean.”⁴⁸ Darwin’s and Wallace’s views were indeed published—together, as they had been presented—in the August issue of the Journal of the Proceedings of the Linnean Society of London. “[If] you have any acquaintance who is a fellow of the Linnean Society, borrow the Journal of the Proceedings for August last,” Wallace advised his friend George Silk, “and in the last article you will find some of my latest lucubrations and also some complimentary remarks thereon by Sir Charles Lyell and Dr. Hooker, which (as I know neither of them) I am a little proud of.”⁴⁹

These were not the reactions of a man concerned about priority. Wallace was clearly elated. To have commanded the attention and respect of three of England’s most respected scientists was one of the greatest honors he could have hoped to attain. Only in retrospect, after fifty years of observing the vagaries of his and Darwin’s evolutionary theory, did he express some annoyance at the outcome of the July 1 meeting of the Linnean Society. His essay had been hastily sketched, he later wrote, and he had had no opportunity to make revisions before it was printed. He later claimed that what no one but he had understood at the time—not even Darwin—was the idea of the constant variability of “every common species in every part and organ,” a fact that could have been known only by someone who had examined, dissected, and prepared thousands of animals from different classes, orders, families, genera, and species. Virtually no one else had noted that “favorable variations” occurred frequently, constantly, in every generation, and in sufficient numbers for the principle of survival of the fittest to effect improvements in the species.⁵⁰

But in 1858, the news was so exhilarating that Wallace emerged from a low point in his travels with renewed excitement in his work. If he had entertained thoughts about coming home earlier than planned, he now cast them aside. To Hooker, he commented that nothing could induce him to quit when his researches had reached “their most interesting point.”⁵¹ It was in this frame of mind that he set off for the island of Batchian to make further discoveries and strengthen his and Darwin’s joint theory with more facts.

Wallace considered it to be the “greatest discovery” he had yet made, and he made it only three days after landing on Batchian. That morning, in virgin forest half a mile from his hut, he had overtaken Ali, who was in high spirits after a successful day of hunting. From Ali’s belt hung a number of birds, one of which he pointed to with obvious pride. “Look, sir, what a curious bird,” Ali said, holding up a specimen the size of a crow. What Ali showed him was puzzling, but after a few moments of study he realized that this was an undiscovered genus and species of bird of paradise, one differing in a remarkable way from every other known bird of the family Paradisaeidae. “The general plumage is very sober, being a pure ashy olive, with a purplish tinge on the back,” Wallace noted with equal sobriety in his journal.

The crown of the head is beautifully glossed with pale metallic violet, and the feathers of the front extend as much over the beak as in most of the family. The neck and breast are scaled with fine metallic green, and the feathers on the lower part are elongated on each side, so as to form a two-pointed gorget, which can be folded beneath the wings, or partially erected and spread out in the same way as the side plumes of most of the birds of paradise. The four long white plumes which give the bird its altogether unique character spring from little tubercles close to the upper edge of the shoulder or bend of the wing; they are narrow, gently curved, and equally webbed on both sides, of a pure creamy-white color. They are about six inches long, equalling the wing, and can be raised at right angles to it, or laid along the body at the pleasure of the bird. The bill is horn color, the legs yellow, and the iris pale olive.⁵²

But to Samuel Stevens and the Zoological Society, Wallace could not suppress his excitement. “I believe I have already the finest and most wonderful bird in the island,” he wrote. “I had a good mind to keep it a secret, but I cannot resist telling you. I have a new Bird of Paradise! of a new genus!! quite unlike anything yet known, very curious and very handsome!!! … Had I seen the bird in Ternate, I should never have believed it came from here, so far out of the hitherto supposed region of the Paradisaeidae.”⁵³

Wallace sent a crude sketch of the bird with its exact dimensions and his detailed description to Stevens, who passed them on to the ornithologist George Robert Gray. The provisional name given by Gray was Paradisea wallacii, subgenus Semioptera, in honor of Wallace’s “indefatigable energy” in the advancement of ornithological and entomological knowledge by traveling to places rarely, if ever, visited by naturalists.⁵⁴ Gray called the bird “Wallace’s standard-wing” because of the white epaulet-like shoulder feathers. A discussion ensued among ornithologists about the affinity of this bird with other birds of paradise, but eventually all agreed with Wallace. In the meantime, as the debate raged, any interested person could view Wallace’s specimen in a square glass case in the bird gallery of the British Museum, along with the three other perfect specimens of birds of paradise—the great, lesser, and king—he had collected.⁵⁵

Except for a two-week excursion to one of the neighboring islets, where he caught the rare Nicobar pigeon, Wallace spent nearly six months on Batchian, one of his more productive and satisfying periods in the archipelago. In mid-April 1859, he returned to Ternate by Dutch steamer and heard more about that other great discovery of his—the theory of natural selection. Another letter from Darwin, dated the previous January, awaited him. “Permit me to say how heartily I admire the spirit in which they [Wallace’s letters to him and Hooker] are written,” Darwin said. “Though I had absolutely nothing whatever to do in leading Lyell and Hooker to what they thought a fair course of action, yet I naturally could not but feel anxious to hear what your impression would be.” Wallace had asked about Lyell’s “frame of mind,” but had to be satisfied with Darwin’s tongue-in-cheek rendition. “He does not give in,” Darwin wrote, “and speaks with horror often to me of what a thing it would be and what a job it would be for the next edition of the Principles if he were ‘perverted.’ But he is most candid and honest, and I think will end by being perverted.”⁵⁶ Lyell, however, left Darwin to speak on his behalf. His failure to write, which was a great disappointment to Wallace, was a sign of his deep distress over a revolutionary doctrine that challenged his fundamental beliefs. Committed to the spirit of scientific inquiry, he seems to have viewed himself as a messenger rather than a spokesman for the Darwin–Wallace theory of evolution, which did not prevent some of his colleagues from misinterpreting his actions at the Linnean Society as a public endorsement of the theory.

Wallace’s lost reply to Darwin’s earlier letter is doubtless filled with numerous “lucubrations,” but Darwin apparently had taken each of them into consideration. “You will see what I mean about the part I believe selection has played [in the development of domesticated animals],” Darwin said in response to a concern that Wallace must have raised about the differences between natural and artificial selection. Regarding Wallace’s attention to the creation of birds’ nests from the standpoint of evolution, Darwin replied, “I have done so [too], though almost exclusively under one point of view, viz to show that instincts vary, so that selection could work on and improve them.” To Wallace’s remarks about bees and beehives (Wallace apparently was uncertain that the construction of a beehive was an instinct, for bees had never been secluded in the larval stage and then loosed), Darwin replied, “I am delighted to hear that you have collected bees’ combs. … This is an especial hobby of mine, and I think I can throw light on the subject.” And he had made significant progress on his book: that January, he announced, he had only two more chapters to write. “My abstract will make a small volume of 400 or 500 pages,” Darwin informed Wallace. “Whenever published, I will of course send you a copy.”⁵⁷

In the same letter, Darwin noted that “everyone whom I have seen has thought your paper very well written and interesting. It puts my extracts (written in 1839 [sic], now just twenty years ago!), which I must say in apology were never for an instant intended for publication, in the shade.” Who these admirers were Darwin never said. A detractor, one Thomas Boyd, wrote a short and unfavorable critique for the Zoologist. Boyd recognized at once the novelty of the papers, which carried the argument about the variation of species “into ground scarcely touched before.” Wallace’s paper clearly impressed him more than Darwin’s “sketch,” which he barely acknowledged. Boyd, who was not an evolutionist, quibbled with Wallace’s choice of the word “tendency,” arguing that “a tendency is not a law of indefinite progress; a tendency to increase is not a law of indefinite increase, neither is a tendency to vary a law of indefinite variation.” His most severe criticism was the absence of “facts, experiments and observations,” precisely the charge that both Wallace and Darwin feared would be leveled against them with the premature publication of their theories. Nevertheless, he truly grasped-without-grasping Wallace’s thesis. “Does he mean that by the tendency to vary we may explain all the differences that [obtain] between different varieties of the same genus, or between different genera of the same order?” Boyd asked. “Or, further still, that we may trace back all organic life, as we see it now, to some unknown root in the far-off geologic ages, some spore, or polype [sic], or vitalized cell, from which everything has since sprung? … [It] seems to me that painting such an ideal picture on the subject is like Science sitting down at the feet of Imagination.”⁵⁸

Meanwhile, despite the promising news on the scientific front, Wallace’s family was alarmed by reports of his various illnesses. His brother-in-law, Thomas Sims, urged him to return home before his health was seriously undermined. Annoyed and unyielding, Wallace replied, “I feel that my work is here as well as my pleasure. Why should I not follow out my vocation? … I am engaged in a wider and more general study—that of the relations of animals to space and time, or, in other words, the geographical and geological distribution and its causes. … As to health and life, what are they compared with peace and happiness?” But there was another powerful reason for Wallace to remain in the archipelago—a financial one. He had not yet accumulated enough money to live on in England, and he felt that he would earn money more quickly by collecting than at any other occupation back home. There was nothing for him in England except surveying, and a job in surveying was not what he wanted. He had decided to devote his life to natural history. What did it matter if people called him an “enthusiast,” Wallace told Sims. “Who ever did anything good or great who was not an enthusiast?” From his perspective, most men were enthusiasts at one thing only: “money-getting.” As he told Sims, “It strikes me that the power or capability of a man in getting rich is in inverse proportion to his reflective powers and in direct proportion to his imprudence. It is perhaps good to be rich, but not to get rich, or to be always trying to get rich, and few men are less fitted to get rich, if they did try, than myself.”⁵⁹

The precarious state of his health did not prevent Wallace from pressing onward, obsessed by his mission to map zoogeographically the entire Malay Archipelago in a manner never yet attempted: through the lens of his theory of natural selection. On May 1, 1859, he left Ternate, circuiting the Moluccas on his way to Menado, on the northeastern tip of Celebes, before touching at Banda and Coupang, on the island of Timor. While waiting in Coupang for the next steamer to Celebes, Wallace wrote a paper that he characterized as an “imperfect outline” of a theory he hoped to “bring forward” on a future occasion. Called “On the Zoological Geography of the Malay Archipelago,” it was a response to a recent article on the zoology of New Guinea by the ornithologist Philip Lutley Sclater.

Sclater had put forth the hypothesis that the straits of Macassar were a “determining line” that separated two zoologically distinct regions, the Asian and Australian, with the island of Lombok “debateable ground” between them, “as Mr. Wallace’s investigations have shown.” On one side were Borneo, Java, and Sumatra, allied “inseparably” with Asia; on the other, Amboyna, Gilolo, Timor, New Guinea, and “probably” Celebes, allied with Australia. After beginning on such a bold note, Sclater advanced no further, merely reviewing the literature published by French and Dutch naturalists and drawing up a list of birds from both sides of the dividing line without offering any explanation for the present-day distribution of animals in the archipelago.⁶⁰

Wallace agreed with Sclater but went one step further, proposing that the division of the Malay Archipelago into two distinct regions “held good” in every branch of zoology. The purpose of his paper, however, was “to mark out the precise limits of each region, and to call attention to some inferences of great general importance as regards the study of the laws of organic distribution.” Why, he asked, were islands that were in such close proximity and so similar in climate and geography populated by radically different faunal groups? Why were islands like New Guinea and Australia, which differed in climate and geography, populated by animals so closely related? Lyell’s explanation for the geographic distribution of animals, based on ordained design, was not a viable solution. If Lyell were correct, one would expect a smooth transition of forms as one moved across the two zoological zones. “Were the Atlantic gradually to narrow till only a strait of twenty miles separated Africa from South America,” Wallace hypothesized, “can we help believing that many birds and insects and some few mammals would soon be interchanged?” Yet such an interchange had barely occurred in the Malay Archipelago, this despite the proximity of the two regions during a long period of geologic time. “Extreme zoological diversity” was the rule here, not the exception.

Celebes was the most anomalous island of all, Wallace wrote. Despite its central position within the archipelago, some of its species seemed to be related to species in Africa! A genus of “baboon-monkeys” (Cynopithecus nigrescens), the bizarre babirusa (or pig-deer, as it was sometimes called), and the cowlike ruminant known as the anoa indicated an African rather than an Australian or Asian origin. The Celebes roller (Coracias temmincki) was classified in Prince Charles-Lucien Bonaparte’s Conspectus Generum Avium in the same genus as birds found in the savannas of eastern and southern Africa, Europe, and the Indian subcontinent. “I am aware of no other spot upon the earth,” Wallace stated, “which contains a number of species, in several distinct classes of animals, the nearest allies to which do not exist in any countries which on every side surround it, but which are to be found only in another primary division of the globe, separated from them all by a vast expanse of ocean.” The only explanation for such an anomaly was a “bold acceptance” of vast changes in the earth’s surface. Facts suggested that Celebes was ancient—more so than its surrounding islands. At one time, he believed, there must have been a great continent, including Africa in the west and Celebes in the east, of which only fragments remained. The intervening land had become “submerged,” leaving pockets of animals and plants that betrayed their past origins. Accidental transmission across the open seas accounted for only an estimated 20 percent of the fauna of Celebes; the rest, he believed, had arrived by a land route. Through similar inductive reasoning, one could develop hypotheses about the past history of other aberrant regions, such as the Galápagos, Madagascar, and New Zealand. “Geology can detect but a portion of the changes the surface of the earth has undergone,” Wallace noted. “It can reveal the past history and mutations of what is now dry land; but the ocean tells us nothing of her bygone history. Zoology and Botany here come to the aid of their sister science.”

Wallace postulated that the narrow strait between Lombok and Bali acted as an impassable barrier to the passage of most land animals, with the exception of the strongest flying birds. No significant connection in recent geologic epochs had existed between the Australian and Asian halves of the archipelago. Based on similar reasoning, he argued that the paucity of species and narrow range of genera in the Galápagos demonstrated that those islands had never had intimate connections with the South American mainland and that animals had arrived there by chance over widely spaced intervals of time.

But these observations explained only half the phenomena of speciation in the Malay Archipelago and other islands. The application of his Sarawak Law and the theory of natural selection to animal distribution could account for the remaining faunal and floral peculiarities. “The regular and unceasing extinction of species, and their replacement by allied forms, is now no hypothesis, but an established fact,” Wallace boldly pronounced, as if every one of his fellow naturalists now believed in evolution. “It is the instances of identity of species in distant countries that presents the real difficulty.”⁶¹

Wallace sent the article to Darwin, who had it read before the Linnean Society on November 3. “Your paper seems to me admirable in matter, style and reasoning,” Darwin wrote. “And I thank you for allowing me to read it. Had I read it some months ago I should have profited by it for my forthcoming volume. … [Y]ou will see that my views are nearly the same with yours, and you may rely on it that not one word shall be altered owing to my having read your ideas. … I was aware that Celebes was very peculiar; but the relation to Africa is quite new to me and marvellous and almost passes belief.”⁶²

On one issue, however, the two men did not yet entirely agree: the means of colonization of oceanic islands. At the time, Wallace concurred with Hooker, Lyell, and most other naturalists about the existence of land bridges and now submerged continents at some point in the past to explain how animals had migrated over vast expanses of water from one region to another. Darwin had discovered other means, far simpler to prove than theories of lost continents and continental extensions, and would elaborate on them in his book.

Once Wallace reached Celebes, he confined his activities to the town of Menado and the surrounding villages from the end of June until September. In early August, he suffered a relapse of malaria and remained in town for two weeks, preparing his specimens while he recuperated. When he regained his strength, he proceeded to the seaside village at the farthest point on the peninsula and camped on a steep black-sand beach backed by a low, scrubby forest and framed on both sides by small rivers. His main object in coming to this wild and lonely place was to capture specimens of the maleo bird (Megacephalon maleo), one of the finest species in the family Megapodiidae, the mound builders. In August and September, when there was little or no rain, they descended “by scores and hundreds” to the beaches of certain bays far from human habitations. His illness had deprived him of witnessing the spectacle at its height, but pairs of birds (male and female) still were emerging, having traveled fifteen to twenty miles from the interior to lay and incubate their eggs in the hot black sand. Like other megapodes, the maleos made unusual nests—heaping up mounds of sand at the high-water mark of the beach by means of the vigorous backward scratching of their short, blunt claws.

Wallace had an opportunity not only to observe their behavior but also to examine the mounds closely. In the mass of sand, he found a number of holes about five feet wide and almost two feet deep. In these holes, the birds had buried seven or eight eggs, each one placed about seven inches apart. At first it seemed to Wallace that each egg must have been laid by a different bird, since on dissection of a pregnant female he discovered a solitary egg completely filling the abdominal cavity, squeezing aside the intestines, while the ovaries contained eight to ten eggs the size of small peas. Once the egg was laid and buried—by the assiduous activity of both male and female—the breeding pair left to feed on fruit in the forest. The natives asserted that the eggs were all from the same female and that the same pair returned every thirteen days to the same hole to lay another egg. Wallace was unable to confirm this cycle, but he judged it likely, given the size of the other eggs maturing in the ovaries.

The peculiar habits of the whole family of megapodes, which differed strikingly (“departed widely,” to use Wallace’s evolutionary terminology) from the behavior of all other birds, provided Wallace with much to speculate about. In a lengthy letter to Sclater, published as an article in the ornithology journal Ibis, he laid out the facts. First, because of the egg’s enormous size, the female could lay only one at a time. Second, a considerable time would have to pass before laying another egg. Third, the total number of eggs that each bird produced every season was about eight, leaving an interval of three months between laying the first and last eggs. If the eggs were hatched in the typical way, he said, they would have to be laid on the ground, forcing the parents to watch each egg constantly to prevent attack by predatory lizards. Moreover, the birds would have to sit on each egg to ensure the successful development of the chick. Complete incubation would be impossible because of the difficulty of obtaining their highly specialized food in the forest. Therefore, Wallace concluded, “the Megapodiidae must behave as they do.” A creationist would explain the animal’s physiology as an adaptation to its instincts and habits, which explained nothing. From the evolutionary viewpoint, it was the other way around: to ensure the species’ survival, the bird’s incubating behavior was an adaptation to its physiology. “A little consideration of the structure of the species in question,” he wrote, “and the peculiar physical conditions by which it is surrounded, would show [its behavior] to be the inevitable and logical result of such structure and conditions.”⁶³

Wallace returned to Menado on horseback, arriving just in time to catch the mail steamer to Amboyna. On the way, the boat stopped at Ternate, where he gathered his mail and sorted specimens. One of the letters was from Darwin, dated April 6, 1859. The letter confirmed that Darwin’s book was ready for publication. “There is no preface, but a short Introduction, which must be read by everyone who reads my book,” Darwin cautioned. Because his book was only an abstract, he would give no references but would allude to Wallace’s two important theoretical publications, showing that “your explanation of your law is the same as that which I offer.” But he was no longer vague about the book’s contents and aims. “You are right, that I came to the conclusion that Selection was the principle of change from the study of domesticated productions; and then reading Malthus I saw at once how to apply this principle. Geographical distribution and geographical relations of extinct to recent inhabitants of South America first led me to the subject. Especially the case of the Galapagos Islands.” Once again, he expressed admiration for Wallace’s attitude toward the joint publication of their papers, and informed him of the letter not sent—the one in which he had stated that he would not publish before Wallace had published. Hooker and Lyell’s subsequent handling of the matter, he said, had changed his mind.⁶⁴

Wallace continued to Amboyna, where he spent the next month sorting and packing his collections before shipping them to London. He summarized his findings from Menado in an article written in October 1859 and published the following April in Ibis. One remarkable statement he made had nothing to do with his own observations. For the first time, he made it clear that the theory of natural selection was Darwin’s theory, not his own. Regarding the maleo’s unusual behavior, he said, “For a perfect solution of the problem we must, however, have recourse to Mr. Darwin’s principle of ’natural selection,’ and need not then despair of arriving at a complete and true ‘theory of instinct.’”⁶⁵ It was at this point that he seems to have closed his species notebook. If he had any lingering hopes of completing his own major work on the subject, they came to an end with Darwin’s announcement. Whatever internal conflict he may have had about the priority issue had been resolved. The position that he took on that occasion was the position he stuck to for the rest of his life: all credit to Darwin; none for himself.

Although Wallace had been forestalled by Darwin in one area of his research, he continued to puzzle over two unsolved problems: the geographic distribution of animals and the origin and diversity of humankind. He channeled his energies into the completion of his mission, zigzagging from island to island until he felt that he could do no more. In the meantime, his impressive collections arrived in London at regular intervals, keeping the taxonomists and anatomists busy cataloguing and classifying birds, mammals, and insects and reporting their findings to the respective scientific societies.

Wallace’s activities astonished his colleagues, even though his own statements undercut his achievements. From Celebes alone, he sent back more than a hundred species of hymenoptera (bees, wasps, and ants)—all new to science. His birds were also admired.⁶⁶ While his collections were praised, his theories were ignored, as though the former were made by one person and the latter by someone else. His most loyal patron, the entomologist William Wilson Saunders, clearly demonstrated this attitude when he addressed the Linnean Society on the subject of Wallace’s enormous collection of hymenoptera:

[N]one has exceeded that whose contents are described in the present paper, in the beauty and variety of the species, as well as in the interest attached to their geographical distribution. … I would particularly call attention to the two forms of the worker of Pheidole notablisi. Though convinced that nothing is created in vain, and that every modification of form has its design, adapting it to the fulfillment of conditions necessary in the economy of the particular species, I feel quite unable even to conjecture the purpose of the enormously enlarged head of the worker major of that species.⁶⁷

At the end of October 1859, Wallace left Ternate for the island of Ceram. “If you want fine birds,” Wallace was repeatedly told by George Robert Gray, John Gould, and other ornithologists, “go to Ceram.” Like a curse, those words would echo through his mind for the next two months as he trekked across the island but collected almost nothing. To Stevens, he complained that Ceram was “a wretched place for birds.” By Christmas, he was half-starved after a stormy and rain-soaked journey by sea. He then sailed for Amboyna, covered head to toe in boils that took nearly two months to clear up—“a not very pleasant memento of my first visit to Ceram.”⁶⁸

While recuperating in Amboyna, Wallace received a copy of Darwin’s Origin of Species, which had been published on November 24, 1859. “If you are so inclined, I should very much like to hear your general impression of the book, as you have thought profoundly on the subject, and in so nearly the same channel with myself. … Remember, it is only an abstract, and very much condensed,” Darwin had written on November 14, ten days before publication. “God knows what the public will think. No one has read it, except Lyell. … Hooker thinks him a complete convert, but he does not seem so in his letters to me. … I do not think your share in the theory will be overlooked by the real judges, such as Hooker, Lyell, Asa Gray, etc. … I think I told you before that Hooker is a complete convert. If I can convert Huxley I shall be content.”⁶⁹

Wallace read the book with “intense interest,” but only after the fifth perusal, he later admitted to Thomas Sims, did he fully appreciate the strength of the entire work.⁷⁰ By his own account, the Origin awed him. He understood at once the magnitude of Darwin’s achievement. “I know not how or to whom to express fully my admiration of Darwin’s book,” Wallace confessed to Bates, who recently had returned to Leicester from Brazil.

To him it would seem flattery, to others self-praise; but I do honestly believe that with however much patience I had worked up and experimented on the subject, I could never have approached the completeness of his book—its vast accumulation of evidence, its overwhelming argument, and its admirable tone and spirit. I really feel thankful that it has not been left to me to give the theory to the public. Mr. Darwin has created a new science and a new philosophy, and I believe that never has such a complete illustration of a new branch of human knowledge been due to the labour and researches of a single man. Never have such vast masses of facts been combined into a system, and brought to bear upon the establishment of such a grand and new and simple philosophy!⁷¹

Wallace told George Silk that the Origin was the greatest book since Isaac Newton’s Principia, insisting that “his name should, in my opinion, stand above that of every philosopher of ancient or modern times.”⁷² He also outlined his initial impressions of the book to Darwin, who did not save Wallace’s critique, but Wallace preserved Darwin’s response: “Most persons would in your position have felt bitter envy and jealousy. How nobly free you seem to be of this common failing of mankind. But you speak far too modestly of yourself; you would, if you had had my leisure, have done the work just as well, perhaps better, than I have done it.”⁷³

It was not long before Wallace learned of the effect of The Origin of Species on the English and American scientific communities. He probably did not see Thomas Huxley’s famous review in the Times, written anonymously but in an unmistakable style that combined erudition and lacerating wit. Immediately after reading the Origin, Huxley became a “convert,” reportedly stating, “How extremely stupid not to have thought of that.”⁷⁴ But Wallace followed the commentaries in the issues of the Annals and Magazine of Natural History of 1860, whose objections were predictable. According to one reviewer, the belief in the independent creation of species was so general an opinion among naturalists that it was almost an “axiom.” Although independent creation could not be proved, he said, the theory of common descent was equally unprovable. He preferred to abide by the universally accepted theory as the one most in accordance with the facts.⁷⁵ Asa Gray, who reviewed the Origin in the August 1860 issue of the Atlantic Monthly, was one of the few men who gave ample credit to the contributions of Wallace’s two seminal papers.⁷⁶ In the stacks of magazines in Wallace’s Ternate cottage were reviews of the Origin, which he read with eagerness, like a parent who has given up his child for adoption but who nevertheless remains keenly interested in any news of its progress. He had many back issues of the Athenaeum, a magazine devoted to literature, science, and the fine arts that had a large circulation among the educated public. The editors were hostile to Darwin’s book, disparaging it—and Darwin—at every opportunity. “He omits nothing and he fears nothing,” wrote one critic. “The work deserves attention, and will, no doubt, meet with it. Scientific naturalists take up the author upon his own peculiar ground; and there will we imagine be a severe struggle for at least theoretical existence. … Having introduced the author and his work, we must leave them to the mercies of the Divinity Hall, the College, the Lecture Room and the Museum.”⁷⁷

Darwin’s book and its implications were the highlight of the annual meeting of the British Association for the Advancement of Science, held at Oxford in early July 1860. Huxley once characterized the association as “a meeting of the savans [sic] of England and the Continent, under the presidency of some big-wig or other … for the purpose of exchanging information.”⁷⁸ Perhaps Huxley’s disparagement was a bit unfair, for the association’s goals were lofty. The objectives that its founding members had set down in 1831 were threefold: first, to give “stronger impulse” and more systematic direction to scientific inquiry; second, to promote the exchange of ideas among British scientists throughout the British Empire with one another and with foreign scientists; and, third, to incite the government and academic institutions to pay greater attention to science and to remove any impedance to its progress.⁷⁹ In the early nineteenth century, most scientists were wealthy dilettantes, not professionals; since its establishment, the British Association, through its annual meetings, helped to promote the professionalization of science and to generate the esteem with which scientists are regarded today. By midcentury, the British Association meetings had evolved into glittering, eagerly awaited affairs, and the 1860 meeting in Oxford would not disappoint, becoming the most famous in the association’s history.

The association had the usual structure: a president, a vice president, a treasurer, and various councils. Every year, it convened in a different city in Great Britain—a boon to local shopkeepers and other businesspeople, as hundreds of scientists and their families descended on the city or town selected. Its gatherings were divided into six sections—Mathematics and Physics, Chemistry and Mineralogy, Geology and Geography, Natural History, Statistics, and Mechanical Sciences (engineering)—and each section had its own president as well as committees and subcommittees. Section D was the Natural History Section, covering zoology, botany, physiology, and ethnology.⁸⁰ It was at one of the meetings of this section that Thomas Huxley supposedly defeated the bishop of Oxford, Samuel Wilberforce, in a battle that earned him the sobriquet “Darwin’s bulldog” and that ultimately would be oversimplified by Darwinian spin doctors into a battle between the forces of enlightenment and the forces of ignorance. The story has been told many times, but unfortunately no one recorded exactly what was said; the encounter was spontaneous and the speeches extemporaneous, and its telling suffers from the Rashomon effect. Such details that exist were reported in the Athenaeum, which Wallace read in Ternate, perhaps while savoring a cup of coffee on the veranda of his tropical pied-à-terre.

“The hospitality [in Oxford] has been limitless,” a reporter wrote in the irreverent style favored by the magazine’s editors. “The colleges, the private houses, have been full. The splendid and piquant New Museum has been open day and night. An unusual flutter of silk and muslin has warmed with a brighter glow the old caves of the Bodleian. Groups that Watteau would have loved to paint have been daily seen under the elms of the Broadwalk or in the shades of Magdalen. … Every morning has brought no less charming receptions.”⁸¹ The atmosphere was charged with excitement. People awaited the confrontation between the two volatile contestants, Huxley and Wilberforce, with an anticipation as frenzied as that at a major sports event. All Wallace would have been able to glean about the conflict was from the unsympathetic Athenaeum correspondent.

“The Bishop of Oxford,” the reporter said, “came out strongly against a theory which holds it possible that men may be descended from an ape, in which protest he is sustained by Prof. Owen … and the most eminent naturalists assembled at Oxford. But others—conspicuous among these, Prof. Huxley—have expressed their willingness to accept, for themselves, as well as for their friends and enemies, all actual truths, even the last humiliating truth of a pedigree not registered in the Herald’s College.”⁸²

Another account of the episode is provided by Joseph Hooker, who was present at the now immortalized duel of egos. Outraged by the bishop’s remarks, in a letter to Darwin written on July 2 he perfectly captured the meeting’s high drama and the passionate exchange between men who harbored murder in their hearts. Although Wilberforce had publicly stated that his mission was to “smash” Darwin in front of a popular assembly, he was not Huxley’s main antagonist. Wilberforce was seen as a puppet of the eminent paleontologist and anatomist Richard Owen, who had once been Huxley’s teacher and was now his greatest enemy. Tension between Huxley and Owen had been building for several years prior to the Oxford meeting. Neither wasted an opportunity to disparage the other. An article in the conservative scientific publication Quarterly Review that criticized The Origin of Species and that allegedly was written by Bishop Wilberforce bore Owen’s unmistakable hand. Both Huxley and Hooker believed that Wilberforce was Owen’s surrogate, and it was at Owen that Huxley lashed out. On Thursday, June 28, shortly before the famous confrontation, a paper by an early supporter of Darwin led to what Hooker called “a furious battle” between Huxley and Owen “over Darwin’s absent body.” The president of Section D, the Reverend John Stevens Henslow, asked Huxley to comment on a paper by Charles Giles Bridle Daubeny, a professor of botany at Oxford, entitled “On the Final Causes of the Sexuality of Plants, with Particular Reference to Mr. Darwin’s Work on the Origin of Species,” which strongly supported Darwin. But Huxley demurred, not wishing to debate a subject—the new theory of evolution—about which “sentiment … unduly interfere[d] with intellect.” Owen picked up the gauntlet. As a fact to controvert Darwin, he pointed to the brain of the gorilla, which differed more from the brain of man, he said, than it did from that of the lower apes. Huxley, who already had investigated and written on this matter, profoundly disagreed. He demonstrated conclusively to his audience that Owen was wrong, that not even a “minor hippocampus” (as the Athenaeum later put it) distinguished the brain of a human being from the brain of a gorilla or a chimpanzee. Huxley’s triumph humiliated Owen, who lusted for revenge. Darwin and his book became the kindling for a planned conflagration.⁸³

Sensing a showdown, visitors packed the lecture hall in the Oxford University Museum of Natural History on Saturday morning, June 30. Henry Draper from New York was scheduled to read his paper “The Intellectual Development of Europe Considered with Reference to the Views of Mr. Darwin,” but members of the association came not to hear Draper—whom Hooker called a “Yankee donkey” in his letter to Darwin—but to hear more about Darwin’s theory and Wilberforce’s rebuttal. The audience was so large that the crowd, numbering perhaps a thousand, had to move from the lecture hall to the more spacious West Room. Near the windows lighting the west side of this room were crowds of women, whose white handkerchiefs waved and fluttered in the suffocating air. Huxley dreaded the confrontation and almost did not attend, but at the last moment Robert Chambers, the still anonymous author of Vestiges of the Natural History of Creation, persuaded him not to “desert the cause.” The meeting’s chairman once again was Henslow, Darwin’s mentor and a professor of mineralogy at Cambridge, whom Darwin considered “wise and judicious.” Not himself an evolutionist, he nevertheless supported free thought and scientific investigation. Seated on Henslow’s right was Wilberforce, with Hooker on his extreme left and Huxley in the center. Four other men, including Draper, shared the platform.

After Draper gave his hour-long presentation in a droning voice, according to Hooker, Henslow selected three men to make comments, but they were all “shouted down” for arguing on theological and not scientific grounds. There followed clamors for the bishop to speak. “Well, Sam Oxon got up and spouted for half an hour with inimitable spirit, ugliness and emptiness and unfairness,” Hooker wrote to Darwin. “I saw he was coached up by Owen and knew nothing, and he said not a syllable but what was in the Reviews; he ridiculed you badly and Huxley savagely.” Wilberforce—“Soapy Sam,” as he was derisively called by Hooker—assured the audience that there was nothing to the idea of evolution. The permanence of species was a fact confirmed by every observation. All hybrid offspring were sterile; no experiments had ever confirmed the transformation of one animal into another. Rock pigeons were what rock pigeons had always been. He then turned to Huxley, Hooker reported, and with an insolent smile said, “I beg to know whether it is through your grandfather or your grandmother that you claim descent from a monkey.”

The unabashed vulgarity of the remark, deemed ungentlemanly to Victorians, was a tactical mistake, for Huxley, a master of character assassination, was now given ample ammunition to mount an attack against his enemy. Letting Wilberforce finish his diatribe, he at first feigned a reluctance to descend to Wilberforce’s level, but after a little encouragement he aimed his elocutionary arrow directly at his adversary and observed that he would rather be descended from an ape than from a man who plunged into scientific questions with which he had no real acquaintance in order to appeal to religious prejudice. According to Hooker, although Huxley’s riposte was “admirable” and turned the tables on Wilberforce, Huxley’s voice could not carry over so large an assembly. Moreover, Huxley did not allude to Wilberforce’s weak points. As another observer would later remark, Huxley scored a victory over the bishop on the issue of good manners rather than good science. Nevertheless, it was a fierce battle, with much commotion among members of the audience; in the heat of the moment, a woman in the audience, one Lady Brewster, fainted.

Dissatisfied with Huxley’s response yet cautious and mindful of his reputation, Hooker handed his name to Henslow as the next speaker. “I swore to myself that I would smite that Amalekite, Sam, hip and thigh if my heart jumped out of my mouth,” he wrote to Darwin. “[T]here I was cocked up with Sam at my right elbow, and there and then I smashed him amid rounds of applause. I hit him in the wind at the first shot in ten words taken from his own ugly mouth.” Hooker made several points, all of which were strictly limited to the botanical implications of Darwin’s theory. First, that Wilberforce could never have read Darwin’s book. Second, that he was “absolutely ignorant” of the fundamentals of botany. Existing species do not change form, Hooker said. All species varied, and it was on these variations that natural selection might act. He could not conceive how anyone who had read the book could make such a mistake. Darwin’s hypothesis was the most powerful explanation of all the phenomena associated with classification, distribution, structure, and development of plants thus far postulated, and would lead to fruitful research. “Sam was shut up—had not one word to say in reply,’ Hooker reported, “and the meeting was dissolved forthwith, leaving you master of the field after 4 hours’ battle.”⁸⁴

Six years of Wallace’s life had been spent in the Malay Archipelago. Now thirty-seven, he needed another six years or more to complete a zoological overview of the region, but two months of lost time recovering from the outbreak of boils convinced him that he could not remain in the archipelago indefinitely. If he was ever to return to England alive—and he had serious concerns that he might not—he had to accelerate his operations. Ali, his most trusted man, could not accompany him on every journey. He required a man with experience, one who could act as his surrogate in places he could not easily reach. With his heart and mind set on sailing home in the near future, he solicited the aid of his old assistant, Charles Allen.

Never one to burn bridges, Wallace had kept in contact with Charles since his departure in 1856. Charles had left Sarawak, having managed to survive several massacres by Chinese insurgents, and moved to Singapore to work on a plantation.⁸⁵ Wallace must have made him an offer he could not refuse—or perhaps he missed the itinerant life and the thrill of the hunt. By February 1860, he was in Ternate, ready to do Wallace’s bidding. Now in his early twenties, he had matured into a good-looking young man over six feet tall, spoke fluent Malay, and was adept at traveling through the islands. Whether or not he had outgrown his irksome qualities did not concern Wallace any longer. Charles would be traveling independently most of the time and thus would not try his patience.

Wallace had not given up his quest for more birds of paradise. New Guinea was his ultimate destination, but he did not want to risk Charles’s life in so dangerous a place. He outfitted him for Mysol, an island just south of the westernmost peninsula of New Guinea, where traders assured him that birds of paradise were more abundant and beautiful than anywhere else in the archipelago. Charles set off for Mysol at the end of the month. Wallace planned to go to the island of Waigiou, off the western tip of New Guinea, stopping one last time in Ceram and picking up Charles along the way. To expedite his journey, he had obtained a letter from the Dutch governor of the Moluccas requesting all village chiefs to supply him with boats and men.

The trip began auspiciously. At Wallace’s first stop in Ceram, the local rajah assembled an impressive entourage for his next destination, where he was promised black and yellow lories and black cockatoos. He traveled in unaccustomed regal splendor, accompanied by four boats rowed by sixty men, with flags flying, drums beating, and spirited shouting and singing. The sea was smooth, the morning clear and bright, the scene exhilarating. When he disembarked, he was treated like a foreign dignitary by the local chief and other potentates, who dressed in their finest regalia in honor of his arrival, and was conducted to a house specially prepared for his use. But lories and cockatoos were not to grace his collections. Eastern Ceram was, like every other part of the island, a tropical paradise with a paucity of wildlife. The fanfare and the alluring tales of birds in profusion were all a ruse to bring a rich European, with his copious stores of spirits, to the village of a friend and ally. Annoyed, he left at once, sailing eastward along the treacherous southern coast, landing at another village, where he was stranded for a month and reduced to pleading in vain for a crew to take him elsewhere.

Eventually Wallace headed south toward the Ke Islands, which he had visited during his first journey to the Moluccas. On the island of Goram, he had a boat built for himself for the nominal price of £9; had he been less vigilant and not personally involved in its construction, he might have waited a year for its completion. After a month, he was the proud owner of a seaworthy prau outfitted with European accoutrements. Just before leaving, Wallace was treated to a preview of the dangers of New Guinea by six of its survivors, who described an attack by natives that left fourteen of their comrades murdered, including one of the rajah’s sons. The village erupted in cries of lamentation and ululations at the terrible news, which put fear into the hearts of his own men. Only by means of threats and strong-arming was he able to assemble a crew willing to accompany him to Waigiou, a less bloodthirsty destination. They left Goram at the end of May 1860, but most of his crew slipped away in a dinghy one night. He raged in vain, vowing to punish the ringleader severely if caught, but they were never seen again.

With his remaining men, Wallace headed back to Ceram, where he was delayed for several days because of difficulty in recruiting another crew. A passing trader informed him that Charles was nearly out of food, pins, and other necessities. He was also ill and planned to return to Ceram if Wallace did not arrive soon. But Wallace never reached Mysol. The weather conspired with an ever-changing current, and he overshot the island several times, finally giving up in despair and sailing north. Finding three islands on his map, he helped his steersman navigate toward one of them, where he anchored and contemplated his next step. Unhappy with his tenuous anchorage, he sent his two best men ashore to cut some vines for rope to tow them to a safer spot. The boat tore loose, and as they drifted farther and farther from shore they called out to the two men, who panicked when they grasped what had happened and ran up and down the shore, too hysterical to notice the numerous logs strewn on the beach that might have made an excellent raft if tied together. Wallace realized that they had resigned themselves to their fate when he saw the smoke of a fire on the beach.

Wallace’s own predicament was no better. With only a two-day supply of water on board and his two best men abandoned on a tropical isle, he guided his remaining crew to another island, where for three days they quenched their thirst with brackish water, reeking of rotten leaves, from a well they had dug near a stand of sago trees. With no hope of rescuing their companions, they sailed to Waigiou, which they reached—more by dint of their wits and luck than by knowledge—just in time to avert death by dehydration. Three more days of nerve-racking sailing brought them to the first human habitation they had seen. The headman, somehow apprised of their imminent arrival, came to their assistance with a present of coconuts and vegetables. Immediately after disembarking, Wallace hired three natives to search for his two men, but after ten days they returned because of bad weather. Wallace refused to give up. Bribing the search party with knives, handkerchiefs, tobacco, and other provisions, he convinced them to make one more attempt. This time they succeeded, and at the end of July he was rejoined by his two men, who were thin and weak but healthy and grateful for Wallace’s persistence, having subsisted on roots, flower stalks, shellfish, and turtle eggs for a month.

The voyage was not all in vain. While he awaited the outcome of the rescue operation, Wallace obtained several good specimens of the red bird of paradise (Paradisea rubra), but he wanted more. He therefore made a short trip by outrigger canoe to a neighboring village, where for six weeks he rented a hut eight feet square by five feet high that was elevated on posts five feet above the ground. His spirits had improved considerably, and by early September he was able to write a playful letter to George Silk. It had been ten months since the date of his last letter from England, he said, but he did not miss the news. He did not care a “straw” for anything but his family and his personal affairs. He joked that while honorable members of the Royal Geographical Society were amusing themselves shooting partridges, he was on the other side of the world in a nameless village shooting—or trying to shoot—red birds of paradise. In his spare moments he read books, and his reading was eclectic: a history of prostitution by a Frenchman and Darwin’s Origin.⁸⁶ For the price of a handkerchief and string of beads per pair of birds, Wallace hired native bird catchers to collect as many birds of paradise as possible. Although these men were diligent, they could not—or would not—bring birds back in good condition. Carrying their booty long distances, they returned with birds invariably covered in ashes, pitch, or some other sticky substance that proved difficult to remove. A few of the specimens were rotting and stinking. Occasionally he was brought a live bird, which gave him a rare opportunity to study the habits of the species. He built a large cage to house them, but each died within a few days.

The technique of capturing a bird of paradise was an art practiced by no more than eight or ten men on the entire island of Waigiou. It involved the ingenious construction of lure and snare, which snagged the leg of a bird and prevented its escape. The little village was the headquarters of these Papuan Papagenos, but Wallace nearly starved to death in the process of adding to his collections. He was amply rewarded for his patience, however, and left at the end of September with twenty-five fine specimens of P. rubra, preserved in various stages of plumage—an achievement not only unique in the annals of ornithology but highly instructive for those unable to observe the bird in its natural habitat. But P. rubra was the only species he was able to collect; once again, he had been misled by his French predecessor, who had acquired seven species of bird of paradise at Waigiou, brought from the interior by native hunters.⁸⁷

In early November, Wallace returned to Ternate, where Charles awaited him. Charles’s collections were disappointing. He told Wallace that he had been forced to return to Ceram to replenish his supply of rice, which was delayed, and was able to return to Mysol for only two more weeks. Wallace spent the next two months organizing his collections and going through mail. He had sixteen thousand insects, birds, and shells to sort through, but none that he considered special or unusual. He told Stevens that Waigiou was “the very poorest island in the New Guinea zoological region.” With demonic determination, he prepared Charles for another mission to New Guinea, this time to a place between Dorey and the island of Salwatty, south of Waigiou. For security, he sent along a lieutenant and two soldiers in the service of the sultan of Tidore. “If he does not succeed this time, I must give up the attempt in despair,” he informed his readers in an article on the ornithology of Ceram and Waigiou published in Ibis.⁸⁸

In early January 1861, Wallace left Ternate for Delli, in East Timor, where he remained until mid-May. In a letter to his brother-in-law, he described his plans to move into his mother’s cottage (she apparently was no longer living with Fanny and Thomas) and asked for the dimensions of the rooms to see whether his collections could be accommodated.⁸⁹ But he was not ready to return to England at once and would remain for another year in the Malay Archipelago. From Timor, he sailed to the Bandas, and from there to Bouru, an island west of Ceram. At the end of June, he returned to Ternate for the last time. In the next two days, he packed his belongings and said his good-byes to the friends he had made there in the past two and a half years. He sailed to Menado and caught a steamer to Java, arriving on July 18 in Surabaya, in the eastern part of the island, where he remained until the end of October. Two days after his arrival, he already was enchanted, pronouncing Java to be “the garden of the East, and probably without exception the finest island in the world.” In Java, Dutch colonialism was in full flower, exercised over a population that had experienced a long history of high civilization. Good roads, modern conveniences, the magnificent remains of ancient cities, and a luxuriant landscape appealed to him aesthetically and intellectually—particularly after nearly three years in the “wild and savage” Moluccas and New Guinea.⁹⁰

For the next two weeks, he resided in a noisy hotel, preparing and sending off his collections, before embarking on a short journey into the interior. Along the way, he passed some of the greatest architectural monuments of the world—the Hindu temple complex at Prabanam and the Buddhist temple at Borobodur—whereupon he was “led to ponder on the strange law of progress, which looks so much like retrogression, and which in so many distant parts of the world has exterminated or driven out a highly artistic and constructive race, to make room for one which, as far as we can judge, is very far its inferior.”⁹¹

Wallace gradually made his way to Batavia (Jakarta) before exploring the western portion of the island. He hiked to the top of a mountain ten thousand feet high in order to view the change from a tropical to a temperate flora and was surprised by the remarkable resemblance of the high-altitude plants to vegetation in faraway Europe. “The common weeds and plants of the top were very like English ones … all closely allied … but of distinct species,” Wallace noted to Fanny Sims. “The fact of a vegetation so closely allied to that of Europe occurring on isolated mountain peaks, in an island south of the Equator, while all the lowlands for thousands of miles around are occupied by a flora of a totally different character, is very extraordinary.” Some botanists, including Richard Spruce, believed that the closely allied but geographically separate species had been divinely created on two different occasions, but the phenomenon deserved a more scientific explanation. Darwin had proposed the following theory in the Origin: during the height of the glacial epoch, temperate forms of plants extended to the tropical zones, and then retreated up these southern mountains as well as northward to the plains and hills of Europe. Some northern species had even crossed the equator and reached the Antarctic. It hardly seemed credible to Wallace that the wide expanse of sea between Java and the European or Asian mainland would have permitted successful migrations of plants by the mechanism that Darwin proposed. For the time being, he remained puzzled.

The Javanese versions of buttercups, violets, wood thistle, and St. John’s wort made him nostalgic for the English countryside. The greater beauty of the tropics was now a grand illusion to him, a dream mainly concocted by romantic travelers who wrote for an audience hemmed in by urban civilization and longing for a balm to soothe their daily miseries. “I still consider and will always maintain that our own meadows and woods and mountains are more beautiful,” Wallace wrote to Fanny. “It is only the great leaves and the curious-looking plants, and the deep gloom of the forests and the mass of tangled vegetation that astonish and delight Europeans, and it is certainly grand and interesting and in a certain sense beautiful, but not the calm, sweet, warm beauty of our own fields, and there is none of the brightness of our own flowers.”⁹²

When Wallace returned to Jakarta, he met up with Charles, who, not surprisingly, had a complicated story to tell. After leaving Ternate in January, he had arrived without mishap in New Guinea. But when he explained his intention of obtaining birds of paradise to the local people, all sorts of objections were raised: it was three- or four-day journey through swamps and mountains; the people of the mountains were savages and cannibals who were sure to kill him; no man in the village would dare to go with him; and so forth. These were half-truths. In reality, Charles was eyed with suspicion. Birds of paradise were items of commerce monopolized by the coastal chiefs, who paid a tribute to the sultan of Tidore. Any direct trade with the people of the mountains would drive up the cost of a bird and lower profits. The chiefs blocked him at every turn. Eventually he was able to hire a prau to take him inland, but the people had somehow been warned of his arrival and refused to assist him. The Tidore lieutenant caused even more difficulties by quarreling with the locals. Charles had to intervene before blood was shed, becoming the protector of those who had come along to protect him. As a white man, he did not feel threatened and used his position to assemble a crew, bribing them with knives, hatchets, and beads. This done, they trekked into the interior, where he remained without an interpreter for a month. Ultimately, he procured no new species of birds of paradise. “Thus ended my search after these beautiful birds,” Wallace later wrote. “Five voyages to different parts of the district they inhabit, each occupying in its preparation and execution the larger part of a year, have produced me only five species out of the thirteen known to exist in New Guinea.”⁹³

On November 1, 1861, Wallace left by steamer for Sumatra. Dutch sovereignty made portions of Sumatra safe, and he was therefore free to travel wherever he liked within Dutch territory without fearing for his life. For a month he followed the numerous paths into the virgin and secondary forests or searched around streambeds, gathering small numbers of rare and interesting birds and butterflies. Relishing his remote location, Wallace told George Silk, “I am here in one of the places unknown to the Royal Geographical Society, situated in the very centre of East Sumatra. … It is the height of the wet season, and the rain pours down strong and steady. … Bad times for me, but I walk out regularly three or four hours every day, picking up what I can.”⁹⁴ By January 1862, he was back in Singapore, making preparations for his final journey home. He left Ali his two double-barreled guns plus ammunition, his tools, and anything else he thought would be of use. He also commissioned a photograph of Ali, which he preserved for the rest of his life and published in his autobiography. The photo shows a young man in his early twenties, with a round, handsome face and dark, curly hair neatly combed back. His countenance is somber; his eyes, dark and intelligent. Wallace described him as “the best native servant I ever had, and the faithful companion of almost all my journeyings among the islands of the Far East.” Now “quite rich,” Ali returned to his wife in Ternate, after which nothing more is known about him.⁹⁵

While Wallace was still in Singapore, his contacts notified him of two live birds of paradise, freshly brought by a trader from the eastern part of the archipelago. On inspection he found two healthy-looking juveniles of Paradisea papuana, not yet in full plumage, in a spacious cage five or six feet square. They were a noisy, active pair, squawking and flitting from perch to perch like jays. The trader asked an astounding £100 for the two birds, but Wallace took the risk and bought them. It paid off. He telegrammed the Zoological Society about his extravagant purchase and received an enthusiastic reply that the zoo would buy the birds at terms that Wallace found agreeable.⁹⁶

The birds were a constant source of trouble and anxiety during the seven-week return journey, with Wallace worrying over them like a mother. Although they readily ate bananas and dried bread, he knew that they needed a more balanced and nutritious diet to survive the arduous journey through multiple climates. To his great relief, he discovered that they would eat cockroaches, which abounded on ships in the tropics, and every evening he went to the ship’s storeroom to brush roaches into a biscuit tin. Another difficulty was keeping their cages clean. For all their beauty, birds of paradise were as filthy as the common crow. In Bombay, Wallace attracted a great number of curious visitors when he brought his birds out onto the hotel veranda. From Bombay, he sailed to Suez, and from there he traveled by rail to Alexandria. He spent a nervous night with his birds in the baggage compartment as the train crossed the cold, windswept desert. From Alexandria, they proceeded to Malta, where he bought smaller cages and remained for two weeks collecting cockroaches from a bake shop because they were difficult to find on board ship during the winter. From Malta, he went on to Marseilles, where he wired Philip Sclater at the Zoological Society to announce his imminent arrival in London with his prizes. On the way to Paris, railway officials refused to let him stay with the birds in the baggage compartment and insisted that they be treated as ordinary baggage, though it was now late March and the temperature hovered near freezing.

At long last, on March 31, 1862, he crossed the English Channel and landed at Folkestone. “I have great pleasure in announcing to you the prosperous termination of my journey and the safe arrival in England (I suppose for the first time) of the Birds of Paradise,” Wallace telegrammed to Sclater. The birds had by now begun to develop their magnificent ornamental plumage. “Another year with a genial temperature, flying room, foliage, and abundance of food, and I hope they will be glorious.”⁹⁷ When he alighted from the train in London, he gladly transferred his charges to the care of the zoo, where one bird survived until Christmas of 1863 and the other until the following March. Thus ended Wallace’s travels to the Malay Archipelago.