The Invention of Nature

Darwin needn’t have worried. When Humboldt received his copy, he replied with a long letter, praising it as an ‘excellent and admirable book’. If his own work had inspired a book like the Voyage of the Beagle, then that was his greatest success. ‘You have an excellent future ahead of you,’ he wrote. Here was the most famous scientist of the age, graciously telling the thirty-year-old Darwin that he held the torch of science. Though forty years Darwin’s senior, Humboldt had immediately recognized a kindred spirit.

Humboldt’s letter was not one of shallow compliments – line after line he commented on Darwin’s observations, quoting page numbers, listing examples and discussing arguments. Humboldt had read every page of Darwin’s account. Even better, he also wrote a letter to the Geographical Society in London – which was published in the society’s journal for all to read – stating that Darwin’s book was ‘one of the most remarkable works that, in the course of a long life, I have had the pleasure to see published’. Darwin was ecstatic. ‘Few things in my life have gratified me more,’ he said, ‘even a young author cannot gorge such a mouthful of flattery.’ He was honoured to receive such public praise, Darwin told Humboldt. When Humboldt later instigated a German translation of Voyage of the Beagle, Darwin wrote to a friend, ‘I must with unpardonable vanity boast to you.’

Darwin was in a frenzy. He worked on a wide range of subjects from coral reefs and volcanoes to earthworms. ‘I cannot bear to leave my work even for half a day,’ he admitted to his old teacher and friend, John Stevens Henslow. He worked so much that he had heart palpitations which seemed always to occur, he said, when something ‘flurries me’. One reason might have been an exciting discovery about the bird specimens that they had brought back from the Galapagos Islands. As Darwin analysed his finds, he began to deliberate on the idea that species might evolve – the transmutation of species, as it was then called.

The different finches and mockingbirds that they had collected on the different islands were not, as Darwin had initially thought, just variations of the familiar birds on the mainland. When the British ornithologist John Gould – who identified the birds after the Beagle’s return – declared that they were indeed different species, Darwin worked out that each island had its own endemic species. As the islands themselves were of relatively recent volcanic origin, there were only two possible explanations: either God had created these species specifically for the Galapagos, or in their geographical isolation they had all evolved from a common ancestor that had migrated to the islands.

Darwin’s finches from the Galapagos Islands (Illustration Credit 17.3)

The implications were revolutionary. If God had created plants and animals in the first place, did the concept of evolving species imply that he had made initial mistakes? Similarly, if species became extinct and God continuously made new ones, did this mean that he constantly changed his mind? It was a terrifying thought for many scientists. The discussion about the possible transmutation of species had been rumbling on for a while. Darwin’s grandfather Erasmus had already written about it in his book Zoomania, as had Jean-Baptiste Lamarck, Humboldt’s old acquaintance from the natural history museum in the Jardin des Plantes in Paris.

In the first decade of the nineteenth century Lamarck had declared that, influenced by their environment, organisms might change along a progressive trajectory. In 1830, the year before Darwin set sail on the Beagle, the battle between the ideas of mutable species versus fixed species had turned into a vicious public row at the Académie des Sciences in Paris.⁵ Humboldt had attended the fierce discussions at the Académie during a visit to Paris from Berlin, whispering a running commentary of disparaging remarks about the fixed species arguments to the scientists sitting next to him. Already in Views of Nature, more than two decades previously, Humboldt had written about the ‘gradual transformations of species’.

Darwin was also convinced that the idea of fixed species was wrong. Everything was in flux, or, as Humboldt said, if the earth was changing, if land and sea were moving, if temperatures were cooling or rising – then all organisms ‘must also have been subjected to various alterations’. If the environment influenced the development of organisms, then scientists needed to investigate climates and habitats more closely. Therefore, the focus of Darwin’s new thinking became the distribution of organisms across the globe, which was Humboldt’s specialty – at least for the world of plants. Plant geography, Darwin said, was a ‘key-stone of the laws of creation’.