Given the apparent serenity of the photographic portraits for which he sat, it is difficult to imagine Charles Darwin fretful. But only a month after the publication of his Origin of Species in 1859, he became very anxious – not, as one might expect, about reviews of his book, but about a letter chastising him for failing to acknowledge his predecessors, the men who had published evolutionary ideas before him. Haunted by the ghostly presence of those who had struck out before him but who had since disappeared into oblivion, Darwin decided to write a proper acknowledgment, in the form of a list of his scientific forebears.
He already knew the names of some of them: the Comte de Buffon, who flirted with evolutionary speculation in the 18th century; Jean-Baptiste Lamarck, the professor of invertebrates at the Jardin des Plantes in Paris who first made his evolutionary claims publicly in 1800; his own grandfather Erasmus Darwin, who had slipped evolutionary ideas between the lines of his poetry and his medical treatises at about the same time; and then there was the anonymous author of a bestselling book of 1844 entitled Vestiges of the Natural History of Creation. Here his list began to break down. There were “some Germans”, he wrote, and “an American (name this minute forgotten)”.
Writing the list was more difficult and time-consuming than Darwin had anticipated. He was no scholar of history, he complained to his friends. To understand and judge these ideas properly, he would have to be able to read French, German, Russian, Arabic and ancient Greek, and have access to manuscripts that had long since disappeared. Unsurprisingly, he failed to produce anything more than a sketch of his intellectual family tree. Six years later he was still adding to the list but the presence of his ancestors no longer rattled him. He had come to see them as kin.
There were others who dabbled with proto-evolutionary questions but about whom he did not know: men such as Leonardo da Vinci, who tried to work out why there were oyster shells in the Verona mountain peaks; the Renaissance potter Bernard Palissy, who was convinced that species were created spontaneously in the alchemical processes of ponds and ditches; the 9th-century Arab philosopher al-Jahiz, who sat with Bedouin nomads counting the web of interdependent species that gathered round desert campfires lit in various locations. What is striking about both the writers on Darwin’s list and those not on it is that their ideas emerged from very similar conditions. He would surely have appreciated the ways in which the history of evolution theory mirrored the very processes of evolution.
Take Aristotle, the first philosopher on Darwin’s list, who spent two years on the island of Lesbos in 345BC collecting facts about species diversity. We now know that he was not an evolutionist, but in 1865 a town clerk from Redhill persuaded Darwin that Aristotle had entertained ideas which were remarkably close to natural selection. He would have recognised the ever-present tension in Aristotle’s work between the myopic collecting of facts and the attempt to discover general laws, as well as his obsession with what Darwin called “borderliners” – organisms, often sea creatures, that did not fit established categories. Darwin was always intimidated by “the ancients”, as he called them, but he would have appreciated Aristotle’s refusal to accept as fact anything he hadn’t witnessed in person.
Consider, too, Abraham Trembley, the Swiss tutor of two Dutch boys growing up in an 18th-century aristocratic household darkened by divorce, who decided to spend a summer showing his boys the miracles of the newly invented microscope. When the boys returned with a jar of minute polyps fished from the ornamental ponds on the family estate outside The Hague, Trembley announced that they would make understanding the strange pond creature their summer project. What he and the boys discovered was quite beyond their comprehension: if you cut the polyp in half, it regenerated itself, a phenomenon entirely at odds with the known laws of nature.
Determined to share the polyp miracle with the world, Trembley posted specimens of the creatures to men and women of science across Europe with instructions on how to cut and regrow the polyp body parts. Appalled by the metaphysical speculation his discovery subsequently inspired among the savants of Paris, London and The Hague, and by the numerous ways in which his findings were exploited by materialists and atheists, Trembley retired from scientific work. The polyps, however, did not retire. They remained at the centre of materialist argument and speculation about transmutations of species for another century.
And then there was Denis Diderot, working through the night in a Paris garret in the 1750s, or arguing for atheism at the dinner tables of the rich, recruiting intellectuals to write for his encyclopaedia project at the same time as he put himself through the most extraordinary programme of reading in the natural sciences – convinced as he was that understanding the connections between species was of critical importance to understanding everything.
Given Darwin’s keen appreciation of how heretical his scientific ideas were and given his belief that, once he proved that species had mutated, the “whole fabric totters & falls”, he would not have been surprised to discover that Diderot was constantly shadowed by a police agent, or that he was arrested in 1749 and spent three years in prison. The materialism and atheism of French subversives of his sort had become very dangerous indeed.
What do the lives of these men, who lived in such different times and places, tell us about the nature of scientific inquiry? They certainly had much in common with each other. Each of them was prepared to risk public censure, imprisonment or the loss of his professional reputation for the sake of a belief in species transmutation. They were all polymaths; most of them were also fluent in several languages. They lived in port or capital cities, metropolises with large populations of itinerant foreigners with diverse religious beliefs and creation myths. Most worked in solitary ways, but all of them relied on intellectual networks to test and disseminate their work.
Many were mavericks, moving restlessly like Aristotle or Leonardo or Erasmus Darwin from one line of inquiry to another. Some had patrons who paid them a stipend or offered access to great libraries. Very few were independently wealthy as Darwin was.
It is tempting to imagine what might have happened if Darwin had been able to follow his ancestors into ancient Lesbos or 18th-century Paris or Cairo, to take a seat on a harbour wall or at a coffee house, or pull up a chair in a salon and discuss some of the questions pressing upon him. The botanist Joseph Hooker, his closest friend, once complained that Darwin’s questions were like the Hydra – cut one head off and several others grew at once in its place.
I suspect that one of the things which would have pleased Darwin most about this history is that the discovery of species mutation and its mechanisms, in which he played such a significant part, was not an inexorable march towards a final truth. Instead, like the history of species as Darwin understood it, the story of the discovery of evolution and natural selection is one of branchings and false starts, atrophies and adaptations, of movements backwards as well as forwards, of sudden accelerations and convergences. Most important of all, it is the story of a community of thinkers, rather than a single brilliant individual.
Rebecca Stott’s latest book is “Darwin’s Ghosts: In Search of the First Evolutionists” (Bloomsbury, £25)