In 1858, Charles Darwin was a well-regarded English naturalist sitting on one of the most important ideas in the history of Western thought, namely evolution by natural selection. He had been gathering his evidence and refining his interpretations for a good two decades, but nevertheless did not feel ready to publish – partly, it seems, because he wanted to make the strongest possible case and still felt more data and cogitation were needed, but also because he was reluctant to be at the centre of the storm of controversy he knew that natural selection would inevitably provoke.
Then, probably in June 1858, Darwin famously received a letter from a younger, less prominent colleague and compatriot who had independently hit on his own formulation of natural selection while gallivanting around the islands of Indonesia. With the letter was enclosed a short manuscript containing the outline of a theory of evolution similar to Darwin’s own. Neither the letter nor the original manuscript is preserved, but the letter apparently contained a request that Darwin forward the manuscript to the eminent geologist Charles Lyell. Darwin complied, but asked Lyell to return the manuscript so that he, Darwin, could offer to send it on to a journal for publication. He was naturally disappointed to have been preempted in this way, fretting to Lyell that his “originality” would “be smashed” by the young upstart, but was nevertheless determined to behave honourably and see to it that the manuscript that had landed on his desk saw the light of day. In the end it was presented along with a summary of Darwin’s own views on evolution at a meeting of the Linnean Society on July 1, 1858. This led to a joint publication later that summer in one of the society’s journals, which had the unwieldy name Journal of the Proceedings of the Linnean Society of London (Zoology). The publication attracted little attention, but the whole episode spurred Darwin to proceed sooner rather than later with his magisterial Origin of Species, which followed in 1859 and indeed provoked the stormy reaction that Darwin had feared and expected.
The young naturalist who wrote to Darwin from Indonesia was called Alfred Russel Wallace (1823-1913), and he was one of those energetic, brilliant, slightly mad individuals whose presence made the 19th century so lively. Unlike Darwin, he was from a relatively poor family, and he left Britain at the age of 25 to become a freelance commercial collector of biological specimens, first in the Amazon and later – after a disastrous shipwreck in which his Amazon collections were lost, followed by a year or so back in Merry England – in the region of southeast Asia he knew as the Malay Archipelago. In later life he returned to English soil and became a husband and father, a prolific writer and public intellectual, and a bit of a crank. He remained on good terms with Darwin and enjoyed the prestige of being the co-discoverer of natural selection, though he eventually began insisting that humanity must have emerged under the auspices of a “superior intelligence” rather than through ordinary evolutionary mechanisms (“I hope you have not murdered too completely your own and my child”, Darwin wrote to Wallace in response). Wallace also weighed in on many of the pressing scientific and political questions of his day. He was against capitalism, unrestricted immigration, and air forces, in favour of women’s suffrage (I told you he was a crank!), convinced of the validity of spiritualism, and prepared to entertain the idea that mothers who were either mutilated themselves or merely interacted with mutilated individuals might give birth to malformed offspring as a result. Browsing through his later essays, reviews and “letters to the editor”, almost all of which are available here, gives one a feeling for the many ways in which public dialogue in the Anglosphere has moved on over the past century or so – and the many ways in which it remains pretty much the same.
In a similar vein, comparing Wallace’s early writings on evolution to what might be called the mainstream Darwinian view of the subject reveals both striking similarities and surprising differences, as I recently discovered for myself when I finally got around to reading Wallace’s work firsthand. The differences tend to be swept under the carpet in heart-warming accounts of the fairness of the 1858 Darwin-Wallace paper and the exemplary subsequent collegiality between its two authors, but they’re definitely there, as historians of science have noted. At least to me, the most salient divergence is that Darwin maintained a bloody-minded focus on differential survival among individuals as the driving force of natural selection, whereas Wallace initially saw evolution more as a process of selection among varieties – that is, large groups of individuals distinguished by sets of shared characteristics – within species. In the manuscript accompanying his 1858 letter to Darwin, sometimes called the “Ternate Essay” because he sent it from the small Indonesian island of Ternate, Wallace wrote:
Neither did the giraffe acquire its long neck by desiring to reach the foliage of the more lofty shrubs, and constantly stretching its neck for the purpose, but because any varieties which occurred among its antitypes with a longer neck than usual at once secured a fresh range of pasture over the same ground as their shorter-necked companions, and on the first scarcity of food were thereby enabled to outlive them. 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; for though in the course of ages varieties of many tints may have occurred, yet those races having colours best adapted to concealment from their enemies would inevitably survive the longest.
Earlier in the essay, Wallace explicitly defined varieties as “races of animals which continually propagate their like, but which differ so slightly (although constantly) from some other race, that the one is considered to be a variety of the other”. The emphasis on “races”, as opposed to individuals, makes Wallace’s mechanism of evolution sound less like classic Darwinian natural selection than like what modern biologists call “group selection” or “interdemic selection”, a concept that is highly controversial but nevertheless has its serious defenders. Wallace, unlike Darwin, seems not to have been very interested in how varieties emerged in the first place.
Wallace used the curious term “antitype” to mean “ancestor”, so he was presumably picturing a series of ancestral species on the line to modern giraffes, each of which included a successful longer-necked variety. An 1855 publication by Wallace, officially entitled “On the law which has regulated the introduction of new species” but usually called the “Sarawak Law Paper” because it was written in the territory of Sarawak in northern Borneo, uses “antitype” in the same sense and also deploys the word “prototype” to mean “descendant”. Given that such usage more or less precisely reverses the dictionary meanings of the two words, it’s probably fortunate that Wallace’s terminology did not survive in the annals of evolutionary biology. Nevertheless, the Sarawak Law Paper is interesting for other reasons. The “law” it proposes is simply that “Every species has come into existence coincident both in space and time with a pre-existing closely allied species” (Wallace’s italics!), which seems obvious in the light of modern scientific knowledge but represented a major intellectual advance in the context of the 1850s. In his excellent book The Song of the Dodo, which contains some vivid writing about Wallace’s ups, downs and accomplishments, David Quammen recounts how Darwin read the Sarawak Law Paper but failed to take it seriously as an indication that Wallace was closing in on a theory of evolutionary change.
The idea of species being coincident with pre-existing allied ones in space, as well as in time, reflects Wallace’s intense preoccupation with biogeography, the science of how organisms are distributed across the Earth’s surface. Although Wallace is best remembered today as the Paul McCartney of natural selection, some of his biogeographic work was original, unparalleled and genuinely ground-breaking. If Darwin had never published, leaving it to Wallace to lay the foundations of modern evolutionary biology, the field might well have had a more group-selectionist and biogeographic flavour in its early years, with who knows what ramifications during its later history. No doubt Wallacism would have ultimately been as corrosive to the intellectual hegemony of Christianity in the West as Darwinism proved to be, but the corrosion might have taken longer without Darwin’s comprehensive marshalling of evidence, persuasive emphasis on selection of individuals, and tenacious ability to pursue arguments to their logical conclusions. As it happened, Darwin not only published his work but produced a “variety” of evolutionary theory that outcompeted both Wallace’s alternative version and the various “antitypes” produced by earlier natural philosophers such as Jean-Baptiste Lamarck, and was indeed so successful that it became virtually synonymous with the whole idea of evolution.
I began this post as an introduction to my thoughts on Wallace’s book on his travels in southeast Asia, The Malay Archipelago, which I read last year. However, my ramblings about Darwin and Wallace seem to have taken on a life of their own, and the book will have to wait.