In February 1858, on a small island in the Moluccas, a thirty five year old English collector lay ill with fever and worked out the mechanism of evolution. Within days he had written it up. He then posted the essay to the one man in England he thought would appreciate it, who happened to be twenty years into an unpublished book on exactly the same subject.
The arrival of that envelope at Down House is one of the most consequential accidents in the history of science.
A Different Kind of Naturalist
Alfred Russel Wallace was born in 1823 into a family of modest means that became poorer as he grew up. He left school at fourteen, trained as a surveyor with his brother, and educated himself in the mechanics institutes and public libraries that Victorian Britain provided for working men who wanted to learn.
The contrast with Darwin is not incidental. Darwin was a gentleman of independent means who sailed as a captain’s companion and never needed to earn from natural history. Wallace was a commercial collector. He funded his expeditions by shipping specimens home to an agent who sold them to museums and private cabinets, and his income depended on how many beetles and bird skins he could preserve and get onto a boat.
Four Years and a Fire
In 1848 Wallace sailed for the Amazon with Henry Walter Bates, another self taught naturalist. They spent four years collecting, mostly separately, in territory that had been barely worked scientifically.
In 1852, sailing home with his collections, his notes, and a menagerie of live animals, the ship caught fire in mid Atlantic. Everything went down with it. Wallace escaped with a small tin box containing a few drawings and notes, and spent ten days in an open lifeboat before being picked up. He was insured for a fraction of the value.
Most people would take that as a sign to find another profession. Eighteen months later he sailed for the Malay Archipelago and stayed eight years.
The Archipelago
Between 1854 and 1862 Wallace travelled through what is now Malaysia and Indonesia, making around seventy separate journeys and collecting some 125,000 specimens, including several thousand species new to European science.
The work produced two major scientific results independent of evolution.
The first is the boundary that carries his name. Wallace noticed that the fauna of the islands changes abruptly along a line running between Bali and Lombok, islands separated by a strait only about twenty miles wide, and continuing north between Borneo and Sulawesi. West of the line the animals are Asian: tigers, monkeys, woodpeckers. East of it they are Australian: marsupials, cockatoos, megapodes. The transition is far sharper than any climate or vegetation difference explains.
The explanation, established much later, is that the western islands sat on a continental shelf connected to Asia during periods of low sea level, while the eastern ones were linked to Australia, and the deep strait between never dried. The Wallace Line is the founding observation of biogeography, and he set out the discipline systematically in The Geographical Distribution of Animals in 1876.
The second result is The Malay Archipelago of 1869, one of the finest scientific travel books in English, which has never been out of print. It is dedicated to Darwin.
The Sarawak Law
Wallace was thinking about the origin of species well before 1858. In 1855, writing from Sarawak, he published a paper stating that every species has come into existence coinciding in both space and time with a pre existing closely allied species.
The formulation stops just short. It describes exactly the pattern that descent with modification would produce, and offers no mechanism. Charles Lyell read it, took it seriously, and urged Darwin to publish before he was forestalled. Darwin, who had been accumulating material since 1837, did not hurry.
Ternate
The mechanism came to Wallace in February 1858 during an attack of intermittent fever, most likely malaria, while he was on Ternate or the neighbouring island of Gilolo.
He later described lying in bed thinking about Malthus’s Essay on the Principle of Population, which he had read years earlier, and about the checks that keep animal populations from growing without limit: disease, famine, predators, accidents. It occurred to him that these checks do not fall randomly. On the whole, the individuals that survive are those best fitted to their conditions, and if variation is heritable, the character of the population must shift with each generation.
He wrote the essay in two evenings. It is titled “On the Tendency of Varieties to Depart Indefinitely from the Original Type”, and it contains natural selection.
He sent it to Darwin, whom he had corresponded with, asking him to pass it to Lyell if he thought it worthwhile.
Malthus, it should be noted, had done the same thing to Darwin twenty years earlier. Both men arrived at the same mechanism from the same book, two decades apart, on opposite sides of the world.
The Joint Paper
Darwin received the manuscript on 18 June 1858 and wrote to Lyell the same day in a state of some distress, saying that he had never seen a more striking coincidence, that if Wallace had his 1842 sketch he could not have made a better abstract, and that all his originality would be smashed.
Lyell and Joseph Hooker arranged a compromise. On 1 July 1858, at a meeting of the Linnean Society of London, three items were read together: extracts from an unpublished essay Darwin had written in 1844, part of a letter Darwin had sent to Asa Gray in 1857 outlining the theory, and Wallace’s essay.
The arrangement established Darwin’s priority by documenting that he had held the theory for fourteen years, while giving Wallace public credit as an independent discoverer. Wallace was in the Malay Archipelago throughout and was not consulted. He learned of it afterwards by letter.
The reading produced no discussion. The society’s president wrote in his annual report that the year had not been marked by any of those striking discoveries which at once revolutionise a department of science.
Darwin abandoned the enormous book he had been writing and produced On the Origin of Species in fifteen months. It appeared in November 1859 and sold out on the first day.
How Wallace Took It
He was, by every surviving account, delighted rather than aggrieved. He wrote to his mother that he had received letters from Darwin and Hooker treating him with great generosity, and he consistently maintained that Darwin’s twenty years of accumulated evidence had earned the credit.
He went further than gracious. His 1889 book defending the theory is titled Darwinism, a word he did more than anyone to popularise, applied to a theory he had co discovered.
Modern historians have raised the question of whether the arrangement was fair, and one line of argument suggests the dates of the mail from Ternate imply Darwin received the essay earlier than he claimed and used it. The documentary case for that is weak and most specialists reject it. What is fair to say is that the settlement was arranged privately by three gentlemen of the scientific establishment on behalf of an absent collector who had no say in it, and that the outcome favoured the one who was in the room.
Where They Disagreed
The two men differed substantially on details, and Wallace’s positions were not always the weaker ones.
He was sceptical of sexual selection as Darwin formulated it, preferring to explain the bright colouring of males through natural selection and the drab colouring of females through the need for camouflage while nesting. The argument continued between them for years in print and in private, with considerable mutual respect.
He was also, in his later writing, unwilling to apply natural selection to the human mind. He argued that the intellectual and moral capacities of humans exceed anything survival requires, and concluded that some other agency must be involved. This position, connected to his interest in spiritualism, dismayed Darwin, who wrote to him hoping he had not murdered his own and Darwin’s child.
The Rest of the Life
Wallace never held a salaried scientific post. He lost most of his money through bad investments and a long legal dispute with a flat earth advocate who refused to pay a wager he had lost. In 1881, Darwin organised a petition to the government and secured him a civil list pension of two hundred pounds a year, which supported him for the rest of his life.
He was a committed social reformer: an advocate of land nationalisation, women’s suffrage, and open access to the countryside, and an outspoken opponent of eugenics at a time when much of the scientific establishment favoured it. He wrote more than twenty books and around seven hundred articles, and he lived until 1913.
His work fits into the tradition of naturalist exploration that Humboldt had established, in which travel, collection and pattern seeking are a single activity. The illustrated record of that tradition is gathered in Illustrating Nature.
What the Episode Shows
Simultaneous discovery is common in science, and it usually means that the pieces were available and someone was going to assemble them. Both men had read Malthus, both had spent years watching species vary across geography, and both were working within a framework that Lyell’s geology had already made thinkable.
What Darwin had that Wallace did not was two decades of evidence: pigeon breeding, barnacle anatomy, seed dispersal experiments, and a vast correspondence with breeders and naturalists. The idea arrived in both minds in an afternoon. The case that convinced the world took twenty years to build, which is why the theory carries one name and not two.
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