Darwin's Backyard
Page 2
Organic life beneath the shoreless waves
Was born and nurs’d in ocean’s pearly caves;
First forms minute, unseen by spheric glass,
Move on the mud, or pierce the watery mass;
These, as successive generations bloom,
New powers acquire and larger limbs assume;
Whence countless groups of vegetation spring,
And breathing realms of fin and feet and wing.5
A better poetic expression of Lamarckian transformism cannot be found. By the time Charles was born in 1809 his grandfather’s poetry was decidedly out of fashion in England, and his politics and sympathy for Lamarck reviled. But not in Edinburgh: even a decade and a half later, when Charles joined his brother in the Scottish capital in 1825, radical politics and radical science were very much part of the scene (though certainly not necessarily approved of).6
By 1827 Erasmus completed his course and moved on to anatomy school in London, leaving his increasingly unhappy brother behind. Charles began working under Robert Edmond Grant, sometime doctor and now an invertebrate zoologist of growing reputation at the university. Grant had lived in Paris for a time, attending lectures by Lamarck and studying under other notable savants: embryology with Étienne Geoffroy Saint-Hilaire, and comparative anatomy with Georges Cuvier. Geoffroy became a friend and defender of Lamarck while Cuvier heaped ridicule upon them both; their animosity eventually erupted into very public verbal duels before the French Academy of Sciences in 1830—an episode deeply interesting to Darwin, which I’ll relate in the next chapter.
Grant took Darwin under his wing. He introduced him to the Plinian Society, established a few years before for students keen on natural history, and took Darwin as his guest to meetings of the Wernerian Natural History Society, ordinarily off limits to undergraduates. Perhaps most importantly, Grant took Darwin with him to explore the tide pools of the Firth of Forth for marine invertebrates. A fan of Lamarck and Geoffroy, Grant studied minute gelatinous sea creatures, seeking in them evidence for “transformism, the search for a unified single set of laws uniting the organic and inorganic domains.”7 Grant was studying tiny colonial polyps, coralline algae, and similar marine organisms, and was sure these creatures represented intermediate forms linking plants and animals. Coralline algae had actually been (mis)classified as plants by Lamarck, who rejected the “animal-plant” linkage idea. Grant, however, held a view more akin to Geoffroy, seeing the unity of all life, plant and animal, as being in one great system. He called them “zoophytes,” or “animal-plants” (mainly consisting of what are called Bryozoa and allied groups today, a form of colonial invertebrate). Grant showed that they formed a free-swimming larval form (decidedly animal-like), yet they looked like plants with blade-like “leaves” undulating in the currents, and could reproduce by budding. “The Animal and Plant Kingdoms are so intimately blended at their origins,” Grant declared, “that Naturalists are at present divided in opinion as to the kingdom to which many well-known substances belong.” In fact, “several organized bodies . . . which have neither roots, nor capillary vessels, nor a digestive stomach, nor other distinct organs or plants or animals, connect the Vegetable and Animal Kingdoms by imperceptible gradations.”8
Darwin marveled at the beauty and intricate complexity of these squishy denizens of the sea, with their pulsations, tiny waving tentacles, and colorful patterns. At Grant’s urging he made observations of his own with a borrowed microscope, learning more than he bargained for in the process. There was the excitement of discovery, to be sure, as when he revealed the animal nature of the enigmatic seaweed-like Flustra by showing that it, too, produced free-swimming “ova” (the larval form) by the thousands, proudly reporting his results in a paper to the local Plinian Society on March 27, 1827. This was Darwin’s first scientific contribution. But his discovery also held another lesson, one that left a bad taste in his mouth: scientific rivalry. Grant felt territorial about his marine invertebrates, and co-opted Darwin’s discovery, evidently feeling that the research program was his alone. Without Darwin’s knowledge, Grant read a similar paper to the Wernerian Society a few days ahead of Darwin’s. Adding insult to injury, he reported the Flustra discovery without acknowledging his student’s role. Darwin was hurt, and also defiant; he decided to carry on with his investigations, documenting free-swimming larval forms in several other species. But his enthusiasm for Grant cooled. When Grant tried to engage Darwin some weeks later, the professor was met with stony silence; as Darwin later described it: “One day, when we were walking together, [Grant] burst forth in high admiration of Lamarck and his views on evolution. I listened in silent astonishment, and as far as I can judge, without any effect on my mind.”9 It’s hard to believe Grant’s declaration made no impression on Darwin, but he wasn’t about to engage in intellectual intimacy with his professor again.
Barely a year later Darwin left Edinburgh; it was clear that medicine was not for him, and neither were intellectual thieves. His father was probably at wit’s end. What to do with a med school drop-out son? Why, send him to Cambridge University, of course. The Anglican church was the obvious alternative: with his cheerful demeanor and penchant for dogs, natural history, and countryside rambles (besides dabbling in his makeshift laboratory), surely Charles would be eminently suited to the respectable and not-too-taxing life of a country vicar. England had (and still has) a long and venerable tradition of vicar-naturalists, personified by the likes of John Ray and Gilbert White. He arrived in January 1828, and although Grant and Edinburgh were left far behind, those “zoophytes” stuck with him.
Cambridge: Beetling, Botanizing, and Geology 101
Charles Darwin spent three years at Cambridge, in comfortable rooms in the front quad of Christ’s College said to have once been occupied by the Rev. William Paley (1743–1805). His plan was to take Holy Orders, and to that end Paley’s writings truly delighted him—especially Paley’s celebrated Natural Theology; or, Evidences of the Existence and Attributes of the Deity, Collected from the Appearances of Nature, a work that Darwin later said “was the only part of the academical course which, as I then felt, and as I still believe, was of the least use to me in the education of my mind.”10 Natural Theology opened with the famous metaphor of the watch and watchmaker: intricacy of structure and adaptation in nature compel us to infer a divine designer, just as the structure and functionality of a watch compel us to infer an intelligent watchmaker. For a time, he fell in with a group of well-heeled young men high in spirits but low in ambition. He later lamented that his time at Cambridge was “worse than wasted,” but he was being a bit hard on himself. After all, he discovered the joys of beetle collecting through his cousin William Darwin Fox, also attending Cambridge at the time, a pursuit that might seem like a pointless hobby but surely gave him firsthand experience with diversity and variation. Many years later his fellow evolutionist Alfred Russel Wallace would look back on his and Darwin’s successes and suggest that it had something to do with the fact that both were ardent beetle collectors as young men. The extraordinary diversity of these insects led the twentieth-century evolutionary geneticist J. B. S. Haldane to quip that the Creator clearly had “an inordinate fondness for beetles.” They impressed Darwin in ways that only made sense later. In the meantime it was fun: “no pursuit at Cambridge was followed with nearly so much eagerness or gave me so much pleasure as collecting beetles,” he wrote in his autobiography.11 His friend Albert Way poked gentle fun at Darwin’s obsession in his cartoon of Darwin astride a giant beetle.
Albert Way’s cartoon of Darwin going a-hunting for beetles. Reproduced by kind permission of the Syndics of Cambridge University Library.
Actually, beetling was more than fun for Darwin: it was practically a blood sport. He threw himself into beetle collecting with competitive abandon, almost coming to blows with a collector whom he had been paying to collect beetles for him, until he discovered the rascal was giving a rival first pick of the rarities he found.
I must tell you what happened to me on the banks of the Cam in my early entomological days; under a piece of bark I found two carabi (I forget which) & caught one in each hand, when lo & behold I saw a sacred Panagaeus crux major; I could not bear to give up either of my Carabi, & to lose Panagaeus was out of the question, so that in despair I gently seized one of the carabi between my teeth, when to my unspeakable disgust & pain the little inconsiderate beast squirted his acid down my throat & I lost both Carabi & Panagaeus!12
But in beetling, too, we get a glimpse of one aspect of Darwin’s modus operandi that he was to later develop into something of an art form, contributing mightily to his later success: the art of procuring help. This likely started with his cousin Fox, an equally keen beetle collector though perhaps not as consumed as Darwin, who came up with the idea of hiring attendants to carry their equipment on long beetling rambles, and collect for them too. What a great idea—well-heeled golfers and hunters have their caddies and gun-bearers, so why not well-heeled beetlers with porters to lug nets, boxes, and traps? The distinguished Darwin biographer Janet Browne insightfully noted that “there were always other people hidden behind Darwin’s immediate achievements.” Darwin’s researches went off in various directions but he never lost the ardor for beetles he developed in his Cambridge years: “Whenever I hear of the capture of rare beetles,” he later reminisced, “I feel like an old war-horse at the sound of a trumpet.”13
But if beetling taught Darwin a certain stick-to-itiveness when it came to collecting as well as the finer points of anatomical structure and variation, these were surely reinforced by his other Cambridge passion: botanizing. In his second year there, Darwin met Rev. John Stevens Henslow, who had been appointed Professor of Botany a few years before. Just 13 years older than Darwin and in many ways quite the opposite of Professor Grant, Henslow was warm and encouraging toward his pupils. Darwin became a regular at Henslow’s weekly countryside botanical rambles, where he was known as “the man who walks with Henslow,” and at his table as a frequent dinner guest, welcomed by Mrs. Henslow and the children. There was no hint of Grantian materialism or transmutationism in Henslow’s teaching, nor jealous sniping over intellectual turf. Henslow was up on the latest thinking from the French “philosophical anatomists,” but put this firmly in the context of natural theology: structure and function, classification and relationships, could be understood in terms of a divine plan. His fellow Cambridge dons approved—scientific Cambridge at that time had a fully institutionalized and doctrinaire “intelligent design” mindset that informed practically all that was taught or studied at the university. Yet there was no conflict between their religion and science: scientific insights were seen as part of the mystery of the Creator’s plan. There was no desperate flailing in the quagmire of biblical literalism here—that had long since been jettisoned, and the Cambridge divines were no less devout for it. Darwin’s eventual discoveries would put him on a collision course with some of the most cherished tenets of the natural theology tradition, but that was later. For now, he fully appreciated and accepted natural theology, eagerly memorizing whole passages from Paley—required reading at the time.
Darwin’s time under Henslow’s tutelage was transformative in several respects, perhaps first in rekindling and stoking his passion for science beyond collecting and identification. A year earlier fellow student John Maurice Herbert, Darwin’s admiring friend and companion on many a beetling jaunt, bowled Darwin over with the gift of a fine Coddington microscope, given anonymously. Henslow revived Darwin’s earlier excitement over microscopic analysis and discovery. But if Henslow’s approach to botanical instruction taught Darwin to “get his eye in” and appreciate intricate structure and individual variation, it also taught him to appreciate the big picture: a philosophical botany, literally global in scope, striving to understand underlying patterns in the geographical distribution of species. Grand insights were articulated by such continental thinkers as the Swiss botanist Augustin de Candolle in his Essai élémentaire de Géographie botanique (1820), and the rockstar of explorer-naturalists, Alexander von Humboldt, in his Essai sur la géographie des plantes (1807). Such works would later be seen as classics establishing new sciences; we’ll explore Humboldt’s and de Candolle’s ideas in Chapter 5, as well as Darwin’s eventual research program and remarkable experiments connected with geographical distribution. That work and more grew from seeds planted by Henslow in 1830 and 1831.
It was at Henslow’s weekly soirees that Darwin was introduced to the luminaries of Cambridge science, notable among them the astronomer John Herschel and philosopher William Whewell, both of whom had a profound influence on Darwin and his growing passion for natural philosophy. At a time when the practice of science was only just becoming self-conscious, these thinkers were helping lay the framework for a methodological philosophy of science: How do we know we know something about nature? What is the best way to figure things out? Herschel received acclaim for his 1831 Preliminary Discourse on the Study of Natural Philosophy, a treatise that introduced a roadmap for inductively gaining insight into nature’s vera causae—“true causes”—and argued for the primacy of natural law governing nature, laws set up by the Creator as the means by which the clockwork universe was regulated. Darwin was flush with excitement over the clarity of Herschel’s luminous treatise: “If you have not read Herschel,” he wrote Fox, “read it directly.”14 Within a decade of Herschel’s treatise, Whewell made his own profound contributions to the philosophy of science, publishing History of the Inductive Sciences (1837) and Philosophy of the Inductive Sciences (1840). The latter not only introduced the concept of consilience, an intuitive and powerful means of gaining insight into vera causae that complemented the Herschelian approach, but also introduced the term “scientist” as an apt replacement for the time-honored but imprecise term “natural philosopher.” “As we cannot use physician for a cultivator of physics,” wrote Whewell, “I have called him a physicist. We need very much a name to describe a cultivator of science in general. I should incline to call him a Scientist. Thus we might say, that as an Artist is a Musician, Painter, or Poet, a Scientist is a Mathematician, Physicist, or Naturalist.”15
The very pursuit of science was being literally defined, analyzed, and systematized by these thinkers before Darwin’s eyes. As an undergraduate he almost surely did not grasp this at the time, but he knew he longed to follow in their footsteps. Literally so, in the case of Humboldt, whose Personal Narrative of Travels to the Equinoctial Regions of America documenting his 5-year voyage of exploration in remotest Central and South America with Frenchman Aimé Bonpland electrified Darwin and other young naturalists of his generation. In April 1831 we see the first indication of a plan in the offing when Darwin wrote excitedly to Fox: “At present, I talk, think, & dream of a scheme I have almost hatched of going to the Canary Islands—I have long had a wish of seeing Tropical scenery & vegetation: & according to Humboldt Teneriffe is a very pretty specimen.”16 Initially the jaunt was to include Henslow and Marmaduke Ramsay, a tutor at St. John’s College, but it was more wishful thinking than realistic on Henslow’s part, given his professorial and parish duties (not to mention his growing family). Darwin worked himself into a frenzy over the trip, rhapsodizing to his sister Caroline:
All the while I am writing now my head is running about the Tropics: in the morning I go and gaze at Palm trees in the hot-house and come home and read Humboldt: my enthusiasm is so great that I cannot hardly sit still on my chair. . . . I never will be easy till I see the peak of Teneriffe and the great Dragon tree; sandy, dazzling, plains, and gloomy silent forest are alternately uppermost in my mind.17
The Canaries trip was not to be, but had, as one happy outcome, his study of geology. To truly emulate Humboldt, Henslow counseled, he must become adept at identifying rocks and minerals, and understanding geological forma
tions and processes. Darwin attended some lectures, and although Henslow personally taught him a bit, the most significant contribution he made toward Darwin’s geological education was introducing him to another Cambridge don, the Rev. Adam Sedgwick.
Sedgwick was Professor of Geology and then-president of the Geological Society of London. That spring of 1831, Sedgwick introduced Darwin to the concept of reading the landscape like a book, finding the stories in the landforms by learning to read them. Darwin sat in on Sedgwick’s lectures, and like the big-picture philosophical issues inherent in botanical geography or the structure of zoophytes, geology awed him. Much discussed at the time was the age of the earth and its vast oceans and continents. Few took seriously the idea of an earth mere thousands of years old, but was it tens or hundreds of thousands, or even millions of years old? After one lecture where Sedgwick held forth on the deep antiquity of the earth Darwin exclaimed to a friend, “What a capital hand is Sedgewick [sic] for drawing large cheques upon the bank of time!”18
Like Henslow, Sedgwick was fond of field excursions with his students, at times leading parties of 60 or more on horseback through the countryside, stopping to lecture at various outcrops and other formations along the way. During his summer holidays he did his own fieldwork, and as luck would have it that year he would be ranging into north Wales, not terribly far from Darwin’s home. Sedgwick was very amenable to having Darwin accompany him. Darwin headed home to Shrewsbury in June 1831, and Sedgwick was due to pick him up in August for a 3-week excursion. Darwin was still mooning about Tenerife, reporting to Fox: “The Canary scheme goes on very prosperously. I am working like a tiger for it, at present Spanish & Geology.”19 In the meantime, Darwin did his best to come up to speed so as to impress Sedgwick. On Henslow’s instructions he bought a good-quality clinometer (a device to measure the angle of slopes, strata, and other formations) and practiced using it for hours on an array of furniture tipped every which way in his bedroom. He even tried his hand at a bit of fieldwork, writing to Fox that he was trying to make a geological map of Shropshire (“don’t find it so easy as I expected”), and trekking 16 miles to study a prominent limestone formation called Llanymynech Hill. His notes from that trip survive, and they reveal a Darwin who consistently had difficulties keeping his compass bearings straight. The Darwin scholar Michael Roberts has suggested that Darwin may have been dyslexic judging by how often he reversed compass readings in his notes.20