by Andrea Wulf
Scientists like Charles Lyell explained that these related plants that were found across huge distances had been produced in several centres of creations. God had made these similar species in tandem at the same time and in different regions, in a series of so-called ‘multiple creations’. Darwin disagreed and began to underpin his ideas with arguments on migration and distribution, using Humboldt’s Personal Narrative as one of his sources. He underlined, commented and devised his own indexes for Humboldt’s books as well as writing reminders to himself on sheets that he glued on to the endpapers – ‘When studying Geograph of Canary Botany look at this part’ – or jotting down in his notebook ‘Study Humboldt’ and ‘consult the VI Vol. of Pers. Narra.’ He also commented, ‘Nothing respect to Species Theory’, when the sixth volume did not yield the necessary examples.
Species migration became a main pillar of Darwin’s evolutionary theory. How did these related species move across the globe? To find an answer Darwin conducted many experiments, for example testing the survival rate of seeds in salt water to investigate the possibility of plants having crossed the ocean. When Humboldt noted that an oak that grew on the slope of Pico del Teide in Tenerife was similar to one in Tibet, Darwin queried ‘how transported was acorn … Pidgeons bring grain to Norfolk – Maize to Artic’. When Darwin read Humboldt’s account of rodents opening the hard-shelled Brazil nuts and how monkeys, parrots, squirrels and macaws fought over the seeds, Darwin scribbled in the margin: ‘so dispersed’.
Where Humboldt was inclined to believe that the conundrum of the movement of plants could not be solved, Darwin took up the challenge. The science of plant and animal geography, Humboldt wrote, was not about ‘the investigation of the origin of beings’. What exactly Darwin thought when he underlined this statement in his copy of Personal Narrative we don’t know, but it was clear that he had set out to do precisely that – he was going to find out about the origin of species.
Darwin began to think about common ancestry, another subject for which Humboldt provided plenty of examples. The crocodiles of the Orinoco were gigantic versions of European lizards, Humboldt said, while ‘the shape of our little house pet is repeated on a larger scale’ in the tiger and jaguar. But why did species change? What triggered their mutability? As one of the main proponents for the transmutation theory, the French scientist Lamarck had argued that the environment had changed, for example, a limb into a wing, but Darwin believed this to be ‘veritable rubbish’.
Darwin found the answer in the concept of natural selection. In autumn 1838 he studied a book that helped him shape these ideas: English economist Thomas Malthus’s Essay on the Principle of Population. Darwin read Malthus’s gloomy prediction that human populations would grow faster than their food supply unless ‘checks’ such as war, starvation and epidemics controlled the numbers. The survival of a species, Malthus had written, was rooted in an overproduction of offspring – something that Humboldt had also described in Personal Narrative when discussing the enormous amount of eggs that turtles laid in order to survive. Seeds, eggs and spawn were produced in huge quantities but only a tiny fraction grew to maturity. There is no doubt that Malthus provided what Darwin called ‘a theory by which to work’, but the seeds of this theory had been sown much earlier when he had read Humboldt’s work.
Humboldt discussed how plants and animals ‘limit each other’s numbers’ as well as noting their ‘long continued contest’ for space and nourishment. It was a relentless battle. The animals that he had encountered in the jungle ‘fear each other’, Humboldt observed, ‘benignity is seldom found in alliance with strength’ – an idea that would become essential to Darwin’s concept of natural selection.
At the Orinoco Humboldt had commented on the population dynamics of capybaras, the world’s largest rodents. As he had paddled along the river, he had observed how rapidly the capybaras reproduced, but also how jaguars chased them on land and how crocodiles devoured them in the water. Without these ‘two powerful enemies’, Humboldt had noted, capybara numbers would have exploded. He had also recorded how jaguars pursued tapirs and that monkeys screamed ‘affrighted at this struggle’.
‘What hourly carnage in the magnificent calm picture of Tropical forests,’ Darwin scribbled in the margins. ‘To show how animals prey on each other,’ he noted, ‘what a “positive” check.’ Here, written in pencil in the margins of Humboldt’s fifth volume of Personal Narrative, Darwin recorded for the first time his ‘theory by which to work’.
In September 1838 Darwin wrote in his notebook that all plants and animals ‘are bound together by a web of complex relations’. This was Humboldt’s web of life – but Darwin would take this a step further and turn it into a tree of life from which all organisms stem, with the branches leading to extinct and to new species. By 1839 Darwin had formulated most of the basic ideas that underpinned his theory of evolution, but he continued to work on it for twenty more years before he published the Origin of Species in November 1859.
Fittingly, even the last paragraph of the Origin of Species was inspired by a similar section in Personal Narrative, highlighted by Darwin in his own copy. Darwin took Humboldt’s evocative description of thickets teeming with birds, insects and other animals7 and turned it into his famous entangled bank metaphor:
It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us.
Darwin was standing on Humboldt’s shoulders.
1 Worried about the little space in the poop cabin, Darwin had asked the captain before the departure if he was allowed to take his own copy of Personal Narrative. ‘You are of course welcome to take your Humboldt,’ the captain assured him.
2 The Beagle also carried a missionary and three Fuegians whom FitzRoy had taken hostage on his previous voyage and brought to England. They were now to return home to Tierra del Fuego where FitzRoy hoped that they would convert their fellow Fuegians to Christianity once he had set up a missionary settlement there.
3 The entire description reads very similarly. Humboldt’s ‘the earth is shaken on its old foundations, which we had deemed so stable’, becomes in Darwin’s journal: ‘the world, the very emblem of all that is solid, moves beneath our feet.’ Humboldt wrote, ‘we mistrust for the first time a soil, on which we had so long placed our feet with confidence,’ and Darwin followed with: ‘one second of time conveys to the mind a strange idea of insecurity.’
4 Darwin also secured government funding to publish Zoology of the Voyage of H.M.S. Beagle – to ‘resemble on a humbler scale’ Humboldt’s magnificent zoological publications, he said.
5 In the corner of the fixed species argument were those who believed that animals and plants became extinct and that God regularly created new ones. Their opponents argued that there was an underlying unity or a blueprint from which different species developed as they adapted to their particular environment – variants of what Goethe had called ‘urform’. They argued that the wings of a bat or the paddle of a porpoise, for example, were all variations of forelimbs.
6 There are several hundred references to Humboldt in Darwin’s manuscripts – ranging from Darwin’s pencil marks in Humboldt’s books to notes on Humboldt’s work in Darwin’s notebooks such as ‘In Humboldt great work’ or ‘Humboldt has written on the geography of plants’.
7 Humboldt wrote in Personal Narrative: ‘The beasts of the forest retire to the thickets; the birds hide themselves beneath the foliage of the trees, or in the crevices of the rocks. Yet, amid this apparent silence, when we lend an attentive ear to the most feeble sounds transmitted by the air, we hear a dull vibration, a continual murmur, a hum of insects, that fill, if we may use the expression, all the lower strata of the air. Nothing is
better fitted to make man feel the extent and power of organic life. Myriads of insects creep upon the soil, and flutter round the plants parched by the ardour of the Sun. A confused noise issues from every bush, from the decayed trunks of trees, from the clefts of the rock, and from the ground undermined by the lizards, millepedes, and cecilias. There are so many voices proclaiming to us, that all nature breathes; and that, under a thousand different forms, life is diffused throughout the cracked and dusty soil, as well as in the bosom of the waters, and in the air that circulates around us.’
18
Humboldt’s Cosmos
‘THE MAD FRENZY has seized me of representing in a single work the whole material world,’ Humboldt declared in October 1834. He wanted to write a book that would bring together everything in the heavens and on earth, ranging from distant nebulae to the geography of mosses, and from landscape painting to the migration of the human races and poetry. Such a ‘book on Nature’, he wrote, ‘ought to produce an impression like Nature herself’.
At the age of sixty-five, Humboldt began what would become his most influential book: Cosmos. A Sketch of the Physical Description of the Universe. It was loosely based on his Berlin lecture series, but the expedition to Russia had given him the final comparative data he had needed. A colossal endeavour, Cosmos was like a ‘sword in the breast that now has to be drawn’, he said, and the ‘opus of my life’. The title, Humboldt explained, came from the Greek word κόσμος – Kosmos – which meant ‘beauty’ and ‘order’, and which had also been applied to the universe as an ordered system. Humboldt now used it, as he said, as a catchphrase to express and encapsulate ‘both heaven and earth’.
And so, in 1834, the very year that the term ‘scientist’1 was first coined, heralding the beginning of the professionalization of the sciences and the hardening lines between different scientific disciplines, Humboldt began a book that did exactly the opposite. As science moved away from nature into laboratories and universities, separating itself off into distinct disciplines, Humboldt created a work that brought together all that professional science was trying to keep apart.
Because Cosmos covered a vast range of subjects, Humboldt’s research rippled into all conceivable areas. Aware that he didn’t and couldn’t know everything, Humboldt recruited an army of helpers – scientists, classicists and historians – who were all experts in their fields. Well-travelled British botanists happily sent him long lists of plants from the countries they had visited. Astronomers handed over their data, geologists provided maps and classicists consulted ancient texts for Humboldt. His old contacts in France proved useful too. A French explorer obliged by sending Humboldt a long manuscript about Polynesian plants, for example, while close friends from Paris such as François Arago were at Humboldt’s regular disposal. At times Humboldt asked specific questions or enquired which pages he should consult in which book, and at others he sent out long questionnaires. When chapters were completed, he would distribute proof pages with gaps that he requested his correspondents to fill in with the relevant numbers and facts, or he would ask them to correct his drafts.
Humboldt was in charge of the general overview, while his helpers provided the specific data and information he needed. He had the cosmic perspective and they were the tools in his grand scheme. Intensely meticulous about accuracy, Humboldt always consulted several experts about each subject. His thirst for facts was insatiable – from questioning a missionary in China about the Chinese dislike of dairy products to querying another correspondent about the number of palm species in Nepal. It was his obsession, he admitted, ‘to pursue one and the same object until I can explain it’. He dispatched thousands of letters and questioned visitors. A young novelist who had recently returned from Algiers, for example, was terrified when Humboldt bombarded him with enquiries about rocks, plants and strata of which he knew absolutely nothing. Humboldt could be relentless. ‘This time you won’t escape,’ he told another visitor, for ‘I have to plunder you.’
As his contacts responded, waves of knowledge and data rolled towards Berlin. Each month new material arrived that had to be read, understood, sorted and integrated. The work expanded as Humboldt went along. With the ever increasing flood of knowledge, he explained to his publisher, ‘the material grows under my hands’. Cosmos was ‘a kind of impossible enterprise’, Humboldt admitted.
The only way to handle all this data was to be perfectly organized about the research. Humboldt collected his material in boxes which were divided by envelopes into different subjects. Whenever he received a letter, he cut out the important information and placed it in the relevant envelope together with any other scraps of material that might be useful – newspaper cuttings, pages from books, pieces of paper on which he scribbled a few numbers, a quotation or a little drawing. In one such box, for example, which was filled with material related to geology, Humboldt kept tables of mountain heights, maps, lecture notes, remarks from his old acquaintance Charles Lyell, a map of Russia by another British geologist, as well as engravings of fossils and information from classicists on geology from ancient Greece. The advantage of this system was that he could collect materials for years, and when it came to writing, all he needed was to grab the relevant box or the envelope. As untidy as he was in his study or chaotic about his finances, when it came to his research Humboldt was unremittingly exact.
Sometimes he scribbled ‘very important’ on a particular note or ‘important, to follow up in Cosmos’. At other times he glued pieces of paper with his own thoughts on to a letter, or tore out a page from a relevant book. One box might contain newspaper articles, a dried piece of moss and a list of plants from the Himalaya. Other boxes included an envelope evocatively entitled ‘Luftmeer’ – air ocean, which was Humboldt’s beautiful term for the atmosphere – as well as materials on antiquity, long tables of temperatures, and a page with citations about crocodiles and elephants found in Hebrew poetry. There were boxes on slavery, meteorology, astronomy and botany among many others. No one but Humboldt, a fellow scientist claimed, could so dexterously tie together so many ‘loose ends’ of scientific research into one great knot.
Usually Humboldt was gracious about the assistance he received, but once in a while he let his famously malicious tongue rule. Johann Franz Encke, the director of the observatory in Berlin, for example, was treated rather unfairly. Encke worked particularly hard, spending many weeks collecting astronomical data for Cosmos. In return, though, Humboldt told a colleague that Encke ‘had become frozen like a glacier in his mother’s womb’. Nor did Humboldt spare his brother the occasional barb. When Wilhelm tried to help his brother’s precarious financial situation by suggesting him as the director of a new museum in Berlin, Alexander was outraged. The position was below his standing and reputation, Alexander told his brother, and he had certainly not left Paris to become the director of a mere ‘picture gallery’.
Humboldt had become used to admiration and flattery. The many young men who gathered around him formed something like his own ‘royal court’, one of the Berlin University professors noted. When Humboldt entered a room it was as if everything was recalibrated and the centre changed – ‘all turned to him’. In silent reverence, these young men listened to Humboldt’s every syllable. He was the greatest attraction Berlin had to offer and he took it for granted that he was the focus of attention. No one was ever able to interject a single word when Humboldt spoke, one German writer complained. His penchant for talking incessantly had become so legendary that the French writer Honoré de Balzac immortalized Humboldt in a comical sketch that featured a brain stored in a jar from which people extracted ideas, and a ‘certain Prussian savant known for the unfailing fluidity of his speech’.
One young pianist who had considered an invitation to play for Humboldt a great honour quickly discovered that the old man could be very rude (and that he had no interest in music whatsoever). As the pianist began to play, there was a moment of silence but then Humboldt continued to talk so loudly
that no one could listen to the music. He was lecturing the audience as he always did and as the pianist played his crescendos and fortes, Humboldt raised his voice in tandem, always outdoing the music. ‘It was a duet,’ the pianist said, ‘which I did not sustain long.’
Humboldt remained an enigma for many. On the one hand he could be haughty, but at the same time he humbly admitted that he needed to learn more. The students at the University of Berlin were astounded to see the old man shuffle into the auditorium with his folder tucked under his arm – not to present a lecture but to listen to one of the young professors. Humboldt attended lectures on Greek literature to catch up on what he had missed during his own education, he said. As he was writing Cosmos, he followed the latest scientific developments by watching the experiments conducted by a chemistry professor and by listening to geologist Carl Ritter’s lectures. Quietly, always sitting in the fourth or fifth row of the auditorium, near the window, Humboldt took notes just like the young students next to him. No matter how bad the weather was, the old man always came. Humboldt was only absent when the king requested his presence, leaving the students to tease that ‘Alexander is skipping lectures today because he’s having tea with the king.’
The university in Berlin which Wilhelm von Humboldt had founded in 1810 and where Alexander von Humboldt attended lectures (Illustration Credit 18.1)
Humboldt never changed his mind about Berlin, insisting that the city was a ‘little, illiterate, and over-spiteful town’. One of the main consolations of his life there was Wilhelm. Over the past years the two brothers had become close, spending as much time together as possible. After Caroline’s death in spring 1829, Wilhelm had withdrawn to Tegel, but Alexander had visited whenever he could. Only two years older than Alexander, Wilhelm was ageing fast. He seemed older than sixty-seven, and had grown increasingly weaker. He was blind in one eye, his hands shook so badly that he couldn’t write any more and his painfully thin body stooped. Then, in late March 1835, Wilhelm caught a fever after visiting Caroline’s grave in Tegel’s park. Alexander spent the next days at his brother’s bedside. They talked about death and Wilhelm’s wish to be buried next to Caroline. On 3 April Alexander read one of Friedrich Schiller’s poems to his brother. Five days later, Wilhelm died with Alexander at his side.