The seven-year period following Darwin's return to England from the Beagle voyage was one of extraordinary activity and productivity in which he became recognised as a naturalist of outstanding ability, as an author and editor, and as a professional man with official responsibilities in several scientific organisations. During these years he published two books—his Journal of researches and The structure and distribution of coral reefs—both of which were to become classics, and fifteen papers, ranging from short notices on various subjects to major theoretical monographs in geology. In addition, he organised and superintended the publication of the Zoology of the voyage of H.M.S. Beagle, for which he described the locations of the fossils and the habitats and behaviour of the living species he had collected. By the end of 1843 he had also completed the writing of a book on the volcanic islands visited during the voyage and had served as a Secretary and Vice-President of the Geological Society of London. All this was accomplished despite the onset of a debilitating illness that cost him many months of work.
Starting a family
Busy as he was with scientific activities, Darwin found time to re-establish family ties and friendships, and to make new friends among the naturalists with whom his work brought him into close contact. In November 1838, two years after his return, Darwin became engaged to his cousin, Emma Wedgwood. The letters they exchanged during the period of preparation for their marriage are amusing, loving, and sometimes touching in the concern they show for one another’s sensibilities. Early in 1839 the couple set up house in London and at the end of the year their first child, William Erasmus, was born. In September 1842, the family, now increased by a daughter, Anne Elizabeth, moved to Down House in Kent, where Darwin was to spend the rest of his life enjoying the ‘extreme rurality’ which he had come to desire so whole-heartedly.
Towards a species theory
Viewed retrospectively, in the light of his greatest theoretical achievement, the most important of Darwin’s activities during the years 1837–43 was unquestionably his work on species and their origin. By the middle of March 1837, apparently as a result of thinking about the significance of John Gould’s and Richard Owen’s identifications of his bird and fossil mammal specimens, Darwin arrived at the daring and momentous conviction that species were mutable (S. Herbert 1980, p. 12; Sulloway 1982b). Using transmutation as a working hypothesis he immediately set himself to collect data and to make notes on any lines of inquiry that he thought might lead to anexplanation of how species came to be as they are (Kohn 1980). Between April 1837 and September 1838 he filled several notebooks with observations and ideas on a wide range of topics. Then, in September 1838, T. R. Malthus’ An essay on the principle of population (1826) furnished him with a causal mechanism for change in species. With this new theoretical point of departure Darwin continued to make notes and explore new avenues of thought, and by the summer of 1842 he felt that his research had progressed to the point at which he was ready to write an outline of his species theory, the so-called 'pencil sketch', based on a principle that he called ‘natural selection’. Seventeen more years of data collecting and the fuller development of the argument were to follow before On the origin of species was published, but the general outline of 1842 is, to a surprising degree, present in the version of 1859.
Darwin’s investigation of the species question went on, literally and figuratively, in the background of his other work. In the foreground, his major occupation in terms of both energy and time was the publication of the scientific results of the Beagle voyage. Even before the Beagle had returned to England, news of some of Darwin’s findings had been spread by the publication by J. S. Henslow and Adam Sedgwick of excerpts from his letters, and the exhibition of his Megatherium bones at the British Association meeting in Cambridge in 1833 had caused great excitement. The fuller account of the voyage and Darwin’s discoveries was therefore eagerly awaited by the scientific community (Rudwick 1982).
As soon as he had sorted his collections into suitable categories for individual experts to work upon, Darwin applied himself to the revision of the diary he had kept during the Beagle voyage. The book was finished and set in type by November 1837, though not published until 1839, when it appeared as the third volume of the Narrative of the surveying voyage of H.M.S. Adventure and Beagle. Darwin’s volume bore the title Journal and remarks but was almost immediately republished and sold separately as Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle. Also in November 1837, Darwin read the fourth of a series of papers to the Geological Society of London. Three of the papers reported results of his Beagle observations. The fourth presented his hypothesis on the formation of mould by earthworms. This explanation of a “new Geological Power”, as William Buckland called it (in his referee’s report to the Society of 9 March 1838), had been developed by Darwin from a suggestion made by his uncle, Josiah Wedgwood II, during one of Darwin’s visits to Maer in Staffordshire.
Darwin’s work and correspondence during the last years of the Beagle voyage make it clear that he had committed himself to a career in science. Within a year of his return to England his papers on coral reefs and on South America had established him as a highly original geologist. The correspondence and the reviews of his papers for the Geological Society Transactions provide ample evidence that he was so regarded by all the leading geologists of England—among them Charles Lyell, Sedgwick, and Buckland (see the reports by Buckland, 9 March 1838, and Sedgwick, [after 15 May 1838]).
The new research Darwin undertook after 1837 was an extension and an application of his Beagle work, and it too was in geology. In 1838 he set out on a geological tour in Scotland, the major object of which was to examine a famous geological puzzle of the time, the parallel terraces, or ‘roads’, of Glen Roy. Darwin had seen similar formations on the Chilean coast and it occurred to him that the same phenomenon—namely the elevation of the land—may have taken place in Scotland. This tour resulted in a major paper for the Royal Society in which he advanced the hypothesis that the roads were a succession of beaches formed as the land rose from the sea (‘Observations on the parallel roads of Glen Roy’, Collected papers 1: 88–137). Darwin later abandoned this view, calling it a ‘gigantic blunder’, when he was eventually convinced that the terraces were beaches of a glacial lake—an explanation first suggested by Louis Agassiz (see Barrett 1973, Rudwick 1974, and L. Agassiz 1840).
In another paper, “On the distribution of the erratic boulders and on the contemporaneous unstratified deposits of South America”, Darwin continued to defend his and Lyell’s theory that floating ice—rather than Louis Agassiz’s glacial sheet ice—was the prime agent in transporting boulders far from their original locations. The following year, 1842, having heard of evidence of glaciation in North Wales, Darwin made a tour there in order to determine whether his iceberg theory would be affected. He was soon convinced that glacial action had indeed taken place, later commenting that “a house burnt down by fire did not tell its story more plainly than did this valley” (Autobiography, p. 70) but again concluded in a paper, “Notes on the effects produced by the ancient glaciers of Caernarvonshire”, that his theory accounted for erratic boulders more satisfactorily than any alternative explanation. Darwin eventually relinquished this theory and his Glen Roy hypothesis when, during the following decades, the effects of glaciation in Wales and Scotland came to be better understood.
Zoology of the Beagle voyage
In addition to his work on geology Darwin undertook to provide a comprehensive programme for the publication of the zoological results of the Beagle voyage. With the help of J. S. Henslow, William Whewell, and other prominent members of the scientific establishment, he obtained a Treasury grant to pay for the necessary engravings, and, having enlisted the leading taxonomical specialists in the several fields, he superintended the publication of the Zoology of the voyage of H.M.S. Beagle from February 1838 to October 1843. The correspondence provides a nearly complete record of Darwin’s arrangements with the Treasury, his publishers, and others involved in the production of the Zoology. The work comprises five parts: Fossil Mammalia, by Richard Owen; Mammalia, by G. R. Waterhouse; Birds, by John Gould; Fish, by Leonard Jenyns; and Reptiles, by Thomas Bell—a total of nineteen quarto issues. Darwin contributed a substantial portion of the text, drawing upon his field notes for geological and geographical data and for the descriptions of the habits and habitats of the species.
Darwin had originally planned to include descriptions of invertebrates in the Zoology but the exhaustion of the government grant forced him to abandon the idea. Instead he decided to publish his own observations and descriptions of the specimens that he considered to be important new discoveries, and did so in articles on Sagitta, finished during the autumn of 1843, and Planariae, described in 1844. Another important specimen was the ‘Arthrobalanus’, an extraordinary new minute cirripede, later named Cryptophialus minutus, which he had collected in the Chonos Archipelago off the coast of Chile. These unexpectedly led Darwin to devote eight years (1846–54) and four volumes to the classification of both the fossil and living members of the sub-class Cirripedia (see S. Smith 1968).
The Beagle specimens and a growing correspondence network
Other naturalists were provided with insects, shells, corals, and minerals. As the correspondence from these years shows, that work put Darwin in communication with most of the leading English naturalists of the time, and he drew heavily upon their specialised knowledge for both the Zoology and his notes on transmutation. In turn, the experts described a large proportion of the Beagle specimens in a wide variety of publications. The beetles were described by F. W. Hope, G. R. Waterhouse, and C. C. Babington; the Chalcididae by Francis Walker; spiders by Adam White; infusoria by C. G. Ehrenberg; fungi by M. J. Berkeley; and corals by William Lonsdale (Collected papers, 2). Darwin’s crustacean specimens, originally entrusted to Thomas Bell, subsequently purchased by John Obadiah Westwood, first Hope Professor of Zoology at Oxford University, and now in the Oxford University Museum, are described in Chancellor et al. 1986.
Only the plants were neglected. During the voyage Darwin had expected that J. S. Henslow would describe his botanical specimens but, despite considerable pressure from Darwin after his return, Henslow produced only two articles—-one on the Galápagos cactus Opuntia and the other on the Keeling Island flora. Darwin’s letters to Henslow show a gradual realisation that his plants would not be described unless they went to some other authority. Towards the end of 1843, he increasingly hoped that William Jackson Hooker or his son Joseph might be tempted to take them on. When Joseph Dalton Hooker agreed to describe the collection, Darwin was both pleased and relieved, and he lost no time exploiting Hooker’s unparalleled knowledge of plant distribution and classification (see Henslow 1837a and 1838; W. J. Hooker and G. A. W. Arnott 1836, 1841; J. D. Hooker 1844–7, 1845, 1846, 1853–5, and 1860). In 1980, two notebooks in Henslow’s hand were discovered that contain lists of Darwin’s plants (see D. M. Porter 1981).
In the extensive communications network that Darwin established as he worked on the geology and zoology of the voyage a most important correspondent, both scientifically and personally, was Charles Lyell. The letters Darwin and Lyell wrote to one another are full exchanges of views and information about their geological work, their expeditions and reading, and their mutual involvement in the affairs of the Geological Society. During the Beagle voyage Darwin had declared himself to be a ‘zealous disciple’ of Lyell, but his theory of coral reef formation, first conceived in 1835, had soon demonstrated that he was by no means bound to the views of his master. Their correspondence began in 1836 and from the start Lyell accepted Darwin on equal terms as a colleague. Many letters from Darwin’s side of the correspondence are preserved (187 of them in the American Philosophical Society’s collection) but some are missing, as we know from the existence of drafts, printed versions in Life and Letters, and from excerpts that Lyell made in his notebooks. Lyell’s letters have suffered an even more severe loss. In a letter to Lyell’s sister-in-law, Katharine Lyell, between 1875 and 1881, when she was collecting material for her Life, letters and journals of Sir Charles Lyell, Bart., Darwin informs her that he is sending her two parcels of letters. Of these, we have only those Katharine Lyell selected for publication and a few copies she made but did not use. Some others, which were not sent to her, have been found in Darwin’s working portfolios together with parts of letters he had cut from Lyell’s originals for use in his work.
Darwin is usually depicted as having been very careful to keep secret his heretical views on species, but the correpondence does not bear out this view, if what is meant is that Darwin was afraid to divulge his conviction that species had evolved. The letters show that at least five of his friends—Lyell, Henslow, Jenyns, Waterhouse, and his second cousin, William Darwin Fox—knew, as he said to Henslow, he was “steadily collecting every sort of fact . . . on the origin & variation of species” (Letter to J. S. Henslow, [November 1839]).
note book, after note book has been filled, with facts
It is true that, until he took J. D. Hooker into his confidence in 1844, Darwin does not appear to have told anyone about his hypothesis of natural selection, but this silence need not be attributed to fear of persecution or ostracism. Quite apart from Darwin’s tentative and uncertain attitude towards his theory at this early stage, his reticence is understandable when one considers the highly complex nature of both the evidence and the argument needed to convince anyone that he had a sound solution to what J. F. W. Herschel in a letter to Lyell had called the ‘mystery of mysteries’ (see Babbage 1837 and Cannon 1961). In the Autobiography (p. 124) Darwin says that before Origin was published he ‘tried once or twice to explain to able men what I meant by natural selection, but signally failed’.
Although there is no discussion of natural selection in the letters, several of them describe how Darwin went about searching for evidence to support his hypothesis. In a letter to Lyell,  September , he wrote: 'I have lately been sadly tempted to be idle, that is as far as pure geology is concerned, by the delightful number of new views, which have been coming in, thickly & steadily, on the classification & affinities & instincts of animals—bearing on the question of species—note book, after note book has been filled, with facts, which begin to group themselves clearly under sub-laws.'
To his cousin, W. D. Fox, [25 January 1841], he wrote: 'If you attend at all to Nat. Hist—I send you this P.S. as a memento, that I continue to collect all kinds of facts, about “Varieties & Species” for my some-day work to be so entitled—the smallest contributions, thankfully accepted—descriptions of offspring of all crosses between all domestic birds & animals dogs, cats &c &c very valuable—'
Darwin’s investigations into the species problem were carried out mainly by putting questions to scientific colleagues and to anyone else he thought might furnish him with reliable data, including gardeners, farmers, and zoo keepers. As his manuscript notes show, he also read a staggering number of works in all fields of natural history and during visits to Shrewsbury and Maer he made botanical observations and planned experiments, in some of which he enlisted Abberley, the Darwin family gardener (see 'Darwin's reading notebooks'; Questions & experiments notebook, CUL DAR 206, especially pp. 13, 14). He also used the notes he had made during the Beagle voyage on, among other subjects, the geographical distribution of genera and species, isolation, the conditions affecting extinction, and the relationship of the fossil record to living species.
A 'theory to work by'
The major new area to which Darwin’s transmutation enquiries led him was one that most naturalists of the time would not have thought of as likely to provide worthwhile scientific conclusions. This was the collecting of information from animal and plant breeders, which Darwin began soon after his return from the Beagle voyage. At that time, as he searched for ‘laws’ of variation, his notes are mainly related to generation, fecundity, and inheritance. After mid-September 1838, when he had his ‘theory to work by’, his interest in breeding became much stronger, with emphasis now focussed on variations as ‘selected’ by breeders.
Silvan Schweber has made the plausible suggestion that the discusssion of experiment as an instrument of investigation in the review of Comte’s Philosophie positive ([Brewster] 1838; see also Manier 1978, pp. 40–5) which Darwin read in August 1838 suggested to him that animal breeding could serve as an experimental investigation of variation and that he thenceforward ‘conceived of artificial selection as the method of exhibiting under the most favourable conditions the properties of “variations” and of studying the dynamics of adaptation resulting from such selection’ (Schweber 1977, p. 258; see also Ruse 1975a and Secord 1981 and 1985 for discussions of Darwin’s interest in artificial selection and its importance to the formulation of his final theory, and Evans 1984, which includes a review of literature on the subject). Darwin himself later, in 1855–8, undertook breeding experiments with domestic poultry and then with pigeons, but during the period of this volume he relied mainly on literature in this field and on friends like Henslow, T. C. Eyton, and W. D. Fox, who were knowledgeable about plant and animal breeding. For other correspondents he devised a questionnaire that he had printed and distributed (Correspondence vol. 2, Appendix V). As P. J. Vorzimmer has pointed out (Vorzimmer 1969), the questions are of the ‘leading’ kind, framed in the light of his transmutation hypothesis and designed to provide data relevant to it or to answer questions raised by pursuing it.
The most important letters on artificial selection preserved from this period are the exchanges with William Herbert, Dean of Manchester, a wealthy plant hybridiser who held heterodox views on species. Darwin must have been encouraged to learn that such an experienced horticulturist maintained that hybrids were not universally infertile, that they were often more fertile than the parent forms, and that they could produce forms that were as distinct and lasting as true species. In short, to Herbert, the distinction between species and varieties had no basis in reality (W. Herbert 1837, p. 341); species were only clearly marked varieties.
Other letters on this subject were directed to correspondents who might be able to supply information on domesticated animals introduced into new environments, on domesticated animals gone wild and their interbreeding, and on comparisons of domesticated varieties in different countries and climates.
While artificial selection occupied a prominent place in Darwin’s investigations during these years he was also occupied with the many new questions raised by his theory. What, for example, were the implications of natural selection for the traditional notions of the harmony of nature, final causes, or centres of creation? In taxonomy, Darwin was concerned with the effect of his theory of descent on the practice of systematists. As the correspondence with G. R. Waterhouse during the 1840s shows, Darwin was anxious to demonstrate that his theory would provide clearer definitions of species and their relationships and provide greater explanatory power than any of the systems of classfication then being employed. Waterhouse was one of Darwin’s closest collaborators and an expert taxonomist, who described the Beagle mammalian specimens for the Zoology and wrote numerous papers on the Beagle coleoptera and other insects. Darwin’s letters to him contain the most open expressions of his evolutionary thinking during this period and in his letters of 1843, Darwin was clearly testing his evolutionary conception of classification with a man whose views he respected. Most of the problems of the taxonomical theories of the time were discussed: what, for instance, was meant by a ‘natural’ system and by ‘levels’ or ‘values’ of groups, and by ‘links’ between genera and families? Darwin found the quinarian system of circles of relationship (a modified form of which Waterhouse supported) arbitrary and unhelpful because it was lacking in clarity in its criteria and objectives. He felt a great advantage of his system, which grouped organisms according to descent from common ancestors, was that it gave a clear direction in classifying. ‘To me, of course,’ he wrote, ‘the difficulty of ascertaining true relationship ie a natural classification remains just the same, though I know what I am looking for' (Letter to G. R. Waterhouse, [26 July 1843]). It is interesting to compare the Waterhouse correspondence with the letters Darwin wrote to Hugh Strickland when both were members of the British Association committee charged with framing rules of zoological nomenclature. Though it was a subject closely related to his concern with classification, Darwin did not find it necessary to put forward his heterodox views on the subject of species. In practice, though Darwin was critical of some of the arbitrary identifications of contemporary systematists and of their lack of clarity about what constituted a genus or species, he found that his theory would require little alteration in zoological taxa as they were worked out at the time. As the late George Gaylord Simpson pointed out: ‘What [Darwin] actually did was to take as given the classifications then current and to show, first, that they were consistent with the theory that their taxa originated by evolution, and second, that evolutionary phylogeny could explain the order that had already been found among organisms' (Simpson 1961, p. 53).
Darwin married Emma Wedgwood in January 1839. His hopes and fears about married life are displayed in a series of notes on marriage written before his engagement (transcribed in Correspondence vol. 2, Appendix IV). During the same period he also recorded some of his earliest memories in an autobiographical fragment (Correspondence vol. 2, Appendix III). The letters that Emma and Darwin subsequently exchanged during their engagement have the directness and ease of a couple who have known each other since childhood, and are captivating in their openness and humour.
One feature of their correspondence is that Darwin had evidently communicated to Emma that he had doubts about religion, though the nature of these doubts is not made explicit. From Emma’s letters one may infer that Darwin expressed uncertainties that were serious enough to give her concern, but not serious enough to deter her, deeply religious as she was, from marrying him. Just after their marriage, Emma states that she has the impression that Darwin did not consider his opinions as ‘formed’, that he was in a state of uncertainty and doubt rather than holding firm convictions. She refers to a ‘danger in giving up revelation’ and to his having once said that ‘luckily there were no doubts as to how one ought to act’ (Letter from Emma Darwin, [ c. February 1839]). These are not matters that she would have fixed upon if Darwin had expressed disbelief in the existence of God. It is far more likely that he presented his religious position as one that was consistent with his scientific beliefs—a theism in which God is first cause and creator of a universe that operates entirely according to laws. From Darwin’s notebooks of this period it is obvious that he had already given up a belief in orthodox church religion and that he no longer accepted creationism or design in nature. There are many references to a Creator, but to a Creator who operates through laws and not through separate ‘acts’ or interventions. Darwin later in life remembered that up to the time of the Origin he was still a theist. However, like many of his memories in the Autobiography, this one has been questioned by scholars who have read the early notebooks which contain many references to materialism and materialistic interpretations of phenomena. Schweber (1977, pp. 304–10) sees a growing agnosticism in the notebooks. Manier (1978, p. 196) also finds Darwin’s claim to have been a theist during this period to be ‘on shaky ground’ but finds the labels of atheist or agnostic also inappropriate. He is inclined to describe Darwin’s belief as closer to a Wordsworthian natural religion than to a Paleyan deism. But Darwin does not directly discuss his religious views or doubts, and his notes are often so terse and ambiguous, so much the thoughts of the moment, that no real clue is given of a consistent or coherent religious view. (See also Gillespie 1979 and Ospovat 1981 for discussions of Darwin’s theism and Brooke 1985 for a review of the question.)
Active and productive as the years 1837–43 were, they were also years during which Darwin was seriously ill for weeks, sometimes months, at a time. In September 1837 he told Henslow that doctors had recommended that he knock off all work. The symptoms—palpitations of the heart—were similar to those he wrote of having at Plymouth just before sailing in the Beagle (Autobiography, p. 79).
My stomach as usual has been my enemy
In 1840 the illness was different. As he wrote to Charles Lyell, [19 February 1840], “it is now nine weeks, since I have done a whole day’s work, & not more than four half days”. This time the symptoms he describes are more like those that were to plague him for the rest of his life. ‘My stomach’, he wrote to FitzRoy, [20 February 1840], ‘as usual has been my enemy—but Dr. Holland tells me he thinks it is only secondarily affected—and that some other wheel works badly—’. The ‘as usual’ suggests that Darwin may have thought his illness stemmed from his recurrent suffering from seasickness in the Beagle. The only other references to stomach disorder in the early years occur after a serious illness at Valparaiso in 1834, when he was incapacitated for several months (See Correspondence vol. 1, letter to Caroline Darwin, 13 October 1834, and letter from R. E. Alison, 25 June 1835).
Henry Holland did not find the cause, nor was he, or any other doctor, ever successful in effecting a cure. Various causes have been suggested, including Chagas disease contracted during the voyage and the taking of arsenical Fowler’s solution for acne; psychosomatic stress symptoms are now generally considered to be the most reasonable diagnosis (see Colp 1977).
The illness of 1840 appears to have been the particularly serious. Three months’ work was lost at the beginning of the year and, on 4 August, Darwin records that he was again taken ill. No new entry occurs in the ‘Journal’ until 14 November, when he states, ‘During this summer when well enough did a good deal of species work.’
The last field trip
One major consequence of Darwin’s poor health during these years was that it put an end to further field work in geology. From his South American days he knew how important good health was for the expeditions that original geological research required. The trip to North Wales in June 1842 was his last field trip: thereafter his geological work was based entirely on the results of his observations during the Beagle voyage.
A little botany
Some reference should be made to the correspondence about the vitality of seeds discovered by William Kemp of Galashiels in a formation thought to have been many thousands of years old. Darwin’s side of the correspondence with Kemp is unfortunately lost, but we have direct knowledge of Darwin’s conclusions from an article that he drafted for Kemp, and which was published in 1844 almost entirely as Darwin wrote it (see Correspondence vol. 2, Appendix VI). Although Darwin was disappointed that the seeds had turned out to be varieties of common English weeds—-when he had hoped for living fossils of unknown varieties—-he was convinced that the long-continued vitality of seeds under certain conditions had been proved. This continued to be a subject of great interest to him, especially in his later work on the geographical distribution of plants, when he conducted numerous experiments to test the ability of seeds to germinate after long submergence in sea-water.
The letters about Kemp’s seeds and the William Herbert correspondence, which was mainly concerned with artificial selection, are almost the only letters in this volume with any significant references to Darwin’s botanical interests, although the notes made during his stays at Shrewsbury and Maer during the summers of 1841 and 1842 show that he was making botanical observations and conducting crossing experiments related to his species work (DAR 106/7 and DAR 206 (Questions & experiments notebook). See also Allan 1977, pp. 128–30).
The letter, on ‘Double flowers’ to the Gardeners’ Chronicle, [late August 1843], expresses his interest in ‘unity of type’, which at that time was a thesis of the so-called ‘science of morphology’, first set forth by J. W. von Goethe. Though widely accepted in taxonomic practice in an idealistic Platonic sense, unity of type was also, if interpreted genealogically, of obvious relevance to the theory of descent (Pencil sketch of 1842, in Foundations, p. 74). Double flowers, like the vitality of seeds and other interests mentioned in the correspondence of 1837–43, which at first seem unrelated, all had a place in the task Darwin had set for himself when, in the spring of 1838, he wrote in his notebook: 'Once grant that species [ interl ] [of] one genus may pass into each other . . . & whole fabric totters & falls.—- Look abroad, study gradation study unity of type study geographical distribution study relation of fossil with recent. the fabric falls!' (Notebook C : 76–7).
[PAGES TO LINK TO]
http://www.darwinproject.ac.uk/darwins-notes-on-marriage [a primary source]
http://www.darwinproject.ac.uk/observations-on-children [a primary source]
http://www.darwinproject.ac.uk/darwins-reading-notebooks [a primary source]