Changing Reputations: Nature and Naturalists in Charles Darwin's On the Origin of Species

By William Montgomery

It is a commonplace that great scientists owe great debts to their predecessors. Newton is said to have remarked that he could see further than others because he stood on the shoulders of giants, and this comment has been accepted as a truism by scientists from his day to ours (Merton). Nevertheless, the relationship between a revolutionary scientist and the people who made his or her work possible is complex. To innovate is to change, to alter, and to modify. The innovator redefines previous work even in making use of it (Kuhn ch. 11).

Charles Darwin was just such a figure. In developing his evolutionary ideas he scoured the scientific literature of his day and pursued complete strangers with odd questions about their special knowledge. His obligations to others were enormous, and yet the use he made of this assembled material was frequently quite novel. He was particularly indebted to the geologist Charles Lyell, who influenced some of the earliest research he ever did and who became an important mentor and friend as his career developed.

Still, as Darwin began thinking about evolution, he grew beyond the more conservative Lyell. He used Lyell's geological ideas but not always in ways that Lyell had intended. Darwin took special care to credit Lyell's thinking, yet even as he acknowledged his friend's work he gave it a new twist.

Darwin did not always treat other scientists as generously as he did Lyell. Darwin could be almost negligent in recognizing scientists with whom he did not want to identify himself. He was terse in dismissing the work of his evolutionary forerunner, Robert Chambers; and he had little more to say about Robert Malthus, who had inspired his idea of natural selection. They were not personal friends, and Darwin made no extra effort to enhance their reputations; nevertheless, he treated their ideas much as he had Lyell's, altering even as he borrowed.

Darwin's great evolutionary book On the Origin of Species was published in 1859, the fruit of a long period of thought and research. He first became convinced of the truth of evolution in March of 1837, shortly after his return from a round-the-world voyage of scientific collecting and observation aboard H.M.S. Beagle (Sulloway). In the intervening period he worked steadily, bringing out six books and a number of major articles, mostly on geology. At the same time he was also reading widely, conducting experiments, and making extensive notes on the subject of species. Darwin kept in close touch with many of the ablest scientists in England and took pains to make sure that his information was complete and up-to-date. Fortunately, he preserved many of his notes, and his correspondents usually saved his letters (Barrett; Burkhardt and Smith). Thus, we are unusually well-informed about his opinions of other scientists and their work.

One individual who attracted Darwin's attention was the publisher and sometime geologist Robert Chambers, author of Vestiges of the Natural History of Creation. This book, published anonymously in 1844, had already advanced a theory of evolution. During the 1830s and early 1840s, geologists had discovered a sequence of fossil forms from extremely primitive invertebrates to mammals quite similar to those now living, which could be identi

fied with successive layers of sedimentary rock. The oldest, most deeply buried rocks contained the most primitive forms, and as one traced the layers toward the present, the number of modern forms increased and grew more familiar. To Chambers, this was a clear sign of evolutionary development, as he explained to fascinated readers in 1844 (148­150). Chambers reassured his readers that this progress was not the result of any blind, mechanical force. God may not have created each plant and animal individually, but it was through the natural development of His laws that ever higher beings came into existence (152­164).

Darwin referred to the Vestiges in the Introduction to the Origin of Species, spelling out his chief reservation about Chambers's idea. In Darwin's eyes it was not enough to offer evidence that species had evolved. A truly successful theory also had to make clear how species were modified to thrive in their environment.

The author of the 'Vestiges of Creation' would, I presume, say that, after a certain unknown number of generations, some bird had given birth to a woodpecker and some plant to the misseltoe, and that these had been produced perfect as we now see them; but the assumption seems to me to be no explanation, for it leaves the case of the coadaptations of the organic beings to each other and to their physical conditions of life, untouched and unexplained. (3­4)

Explaining the coadaptations of nature was, of course, one of the major goals of the Origin of Species. The reference to Chambers's book thus served Darwin as a convenient springboard for an explanation of his own intentions. He did not name the author since Chambers was still protecting his anonymity and would do so to the end of his life in 1884. However, Darwin had guessed his identity in early 1846 after reading Chambers's anonymous reply to a harsh review of the Vestiges (To J. D. Hooker [Feb. 10, 1846] in Burkhardt and Smith 3:289) A year later Darwin had his guess confirmed, if ever so discreetly, by Chambers himself.

Darwin went to see Chambers in London in early March, 1847. Darwin had become embroiled in a dispute over his theory about the origins of the raised beaches that line the walls of Glen Roy in

Scotland. He hoped to obtain from Chambers more information about Glen Roy and about the views of the Scottish geologist David Milne, who had criticized his work. Darwin and Chambers had never met before, but they got on well, and Darwin evidently considered Chambers's information useful. A punctiliously courteous man, Darwin asked no questions about the Vestigesafter all, Chambers would only have answered "no." In mid-April, though, Darwin received an anonymous, but revealing present in the mail, a presentation copy of the sixth edition of the Vestiges. The gift left him quite confident that he was right about its author (To Robert Chambers, Feb. 28, 1847 and To J. D. Hooker, April 18, 1847, in Burkhardt and Smith 4:19 and 36).

Scientists had very diverse reactions to the Vestiges. The young explorer Alfred Russel Wallace was immediately converted by Chambers, and started looking for evidence to bolster his views (McKinney 9­12). However, the usual reaction was quite negative. Adam Sedgwick, the pious Cambridge professor of geology, gave it a bitterly hostile review when it first appeared (Secord in Chambers xxxi-xxxii). Darwin, who of course sympathized with Chambers's purposes even if he rejected many of his scientific mistakes, was appalled at the review. It inspired him to move very carefully in revealing his own ideas. Darwin got another jolt in 1854 when Thomas Henry Huxley, whom he had begun to think of as a possible supporter, gave the tenth edition of the Vestiges a cutting review. Huxley had no religious objections to evolution, but he would not forgive the amateurishness of some passages in the book, and he genuinely disagreed with Chambers's belief in geological progress (Richards 148-49). This was awkward for Darwin, who had begun to believe in some measure of progress himself. He gently noted to Huxley, "I am almost as unorthodox about species as the Vestiges itself, although I hope not quite so unphilosophical." (To T. H. Huxley, Sept. 2, [1854], Burkhardt and Smith 5:213)

Darwin's comments in the Introduction to the Origin were clearly intended to disarm critics who had disliked Chambers's book. Darwin wanted to make plain at the outset that his own approach to species change was quite different from that of the Vestiges. How

ever, for many biologists Darwin went much too far. Richard Owen, the leading comparative anatomist in England, probably spoke for many of his colleagues when he distanced himself from many of Darwin's innovations. Owen was ambivalent about the transmutation of species. He would not endorse the idea openly, but he clearly sympathized with many of the arguments in its favor. This is obvious in his review of the Origin, where he vacillated between criticizing Darwin and suggesting that some transmutationist ideas, especially his own and those of Robert Chambers, did deserve consideration. Chambers had proposed that modifications in the growth process of immature organisms might lead to new species. Owen was not fully persuaded by Chambers's idea, but he obviously preferred it to natural selection (185­186). In addition to his scientific objections to natural selection, Owen may also have disliked its rigorous secularism. Despite Chambers's coy anonymity and despite the criticism that professional scientists had heaped on the Vestiges, his theory made a place for the works of God in a way that natural selection did not. If Owen had to choose between them, he would side with Chambers.

Darwin forced Owen to choose, and before long he forced most other scientists to choose as well. Within a decade, the arguments of the Origin of Species had converted the majority of biologists in England and North America to the idea of evolution. Nevertheless, argue as he might, he could not convince them that natural selection was the primary mechanism of evolutionary change. Most of them eventually made the same choice that Owen did and opted for some version of evolution along the lines Chambers had suggested. As the historian Peter Bowler has remarked, "The system that had been rejected as virtually atheistic in 1844 was now revived as a fall-back position by those who wished to preserve the role of design against Darwin's more militantly naturalistic theory." (Eclipse 49) Charles Darwin made Robert Chambers a good Christian in the eyes of their contemporaries. Chambers held to his secret until his death, but after the Origin of Species appeared, he had nothing to apologize for.

Darwin and Chambers hardly knew one another, but Darwin

and Charles Lyell were close friends and scientific allies. Lyell, a wealthy Scottish landowner, had studied law as a young man but could not practice due to bad eyesight. Since he enjoyed an independent income, he chose to devote his life to geology and soon established himself as one of the leading members of the socially prestigious Geological Society of London. He was particularly known for his studies of volcanos, the Tertiary period, movement in the earth's crust, and those recent deposits that his contemporaries called Diluvial and that we call Pleistocene. Lyell did more than anyone else to establish that these deposits could not have been produced by a gigantic prehistoric flood in the manner of the Biblical deluge and must have been produced by more gradual processes (Herbert 489).

Darwin had first become aware of Lyell's ideas aboard the Beagle, where he read Lyell's newly published masterpiece, the Principles of Geology. According to Lyell, all of past geology could be explained by references to processes still observable. Earthquakes, volcanos, and erosion were the principle active events of geology. The land might rise and gradually be worn away or it might subside, but everything happened slowly over vast expanses of time. To young Darwin, chipping fossils out of South American river beds, Lyell's message was immediately plausible. Darwin was discovering the remains of large Pleistocene mammals whose collective demise demanded explanation. Most geologists of the time assumed that such animals must have been destroyed by some great deluge, far more destructive that anything that humans had witnessed: this was the view of Alcide d'Orbigny, who had also explored in South America. Darwin, however, followed Lyell in insisting that they had perished a few at a time in the sort of ordinary floods, famines, and ferocity that overcome living beings every day (Voyage 165­66).

The greatest triumph of Darwin's voyage was the theory he devised to explain the phenomenon of coral reefs. His experience in studying the rising seacoast of Chile supported Lyell's idea of the importance of gradual changes in the elevation of the land. Thinking about his forthcoming trip to the Pacific, Darwin surmised that where coastlines or tropical islands were subsiding, coral reefs might

develop as corals slowly built upward on top of one another. As each dying generation sank further beneath the waves, it would provide a platform for the support of its offspring. This was an improvement on Lyell's own rather implausible notion that such reefs simply formed on the tops of extinct volcanos, and Darwin was able to visit a large number of reefs in the Pacific and Indian Oceans that exemplified the process at work (Structure).

Following Darwin's return to England, he and Lyell were soon friends. The older man had high praise for Darwin's coral reef theory and encouraged him in publishing the findings of his voyage. For his part, Darwin became the most important supporter of Lyell's ideas among the scientists who gathered at the Geological Society of London. Even after Darwin moved from London to Down, the two kept in touch through long letters offering advice and suggestions on one another's books. As Darwin freely admitted, all his early geological books "came half out of Lyell's brains." (To Leonard Horner, Aug. 29, [1844], Burkhardt and Smith 3:55) For his part, Lyell appreciated Darwin's support, for he was often at odds with most of his other colleagues on important issues. He insisted that the past could be entirely explained through gradual processes without reference to great catastrophes, a point that was also important to Darwin. Even more strikingly, Lyell recognized no discernable direction in the geological past, only an endless recycling of the material landscape as it rose and decayed. Lyell extended this idea even to the fossils in the rocks, professing to detect no sign of progress over time. He recognized, of course, that older formations seemed to contain no remains of higher animals or plants; however, he dismissed their absence as an accident of poor preservation. Sooner or later examples would be found (Lyell 130­153).

Most other geologists disagreed completely with this idea. Their research showed increasing numbers of higher forms in the more recent formations, and as their studies became more thorough, they found no exceptions to this rule. Darwin's reaction was more complicated. Privately, he had come to believe in evolution; for him, the higher forms must somehow have arisen from lower ones. Lyell's antiprogressive theory might seem inconsistent with evolu

tion, and Lyell hadin part for this very reasonopposed the evolutionary ideas of Jean Baptiste Lamarck. Nevertheless, Darwin had his own problems with the progressivist belief in a geological record that was relatively intact. For the most part, surviving fossils show little indication of change over time. They may progress in a general sense, but examples of gradual transition from one form to another are unusual. If Darwin wanted to defend evolution, he, like Lyell, also had to assume that the preserved fossils represent only a small remnant of the living beings that once existed (Rudwick ch. 4). The Origin of Species records Darwin's agreement with Lyell as forcefully as possible. He completely endorsed Lyell's idea that the rocks bear testimony to an enormous passage of time. In fact, he thought Lyell's work on this subject had achieved "a revolution in natural science." (282) Darwin urged anyone who examined great sedimentary deposits thousands of feet thick to "remember Lyell's profound remark, that the thickness and extent of sedimentary formations are the result and measure of the degradation which the earth's crust has elsewhere suffered." (283­284) To be sure, this idea of an earth that constantly recycled its materials was by no means original with Lyell; it was pioneered by James Hutton, Lyell's Scottish predecessor (Bowler, Evolution 45­49). Nevertheless, in the Origin, Darwin chose to emphasize the work of his friend.

When Darwin set out to defend the idea that the fossil record has been poorly preserved, he also identified Lyell, along with Edward Forbes, as the chief advocate of this position. Indeed, at one point he echoed Lyell's antiprogressivist faith that mammals might well have existed in the older history of the earth even if their fossils had not yet been found. "Nor is their rarity surprising, when we remember how large a proportion of the bones of tertiary mammals have been discovered either in caves or in lacustrine deposits; and that not a cave or true lacustrine bed is known belonging to the age of our secondary or palaeozoic formations." (289) Of course, the real point of this argument was not so much to defend Lyell as to explain away the scarcity of intermediate gradations between fossil forms (293); still, it was an awkward concession for an evolutionist to make.

In a later passage Darwin grappled directly with the issue of evolutionary progress. It gave him a great deal of trouble because, as he put it, "naturalists have not as yet defined to each other's satisfaction what is meant by high and low forms." (336) He mentioned the zoologist Louis Agassiz, who believed that "ancient animals resemble to a certain extent the embryos of recent animals of the same classes." His own response to this idea was ambivalent: "I must follow Pictet and Huxley in thinking that the truth of this doctrine is very far from proved. Yet I fully expect to see it hereafter confirmed, at least in regard to subordinate groups, which have branched off from each other within comparatively recent times." (338) Darwin's expertise in comparative anatomy was limited to barnacles, and he was reluctant to challenge the authority of Huxley, who had excoriated Chambers over just this issue (Richards 145­46). Still, as an evolutionist, he could hardly reject the notion of progress entirely. In saying this, he was not necessarily contradicting his mentor Lyell. If progress had occurred only among subordinate groups of recent origin, paleozoic mammals might yet be unearthed.

In this way, Darwin avoided serious disagreement with Lyell while maintaining some degree of evolutionary progress. There was not very much progress, and it took place rather late in the game among creatures that all belonged to the same general category. Darwin did not actually mention Lyell in making this formulation, but it was probably no accident that his modest claims for progress fell within the permissible limits of Lyell's thinking. It was probably also no accident that Darwin allowed himself just enough progress to accommodate the emergence of human beings from some more primitive mammalian ancestor. It was a tight squeeze, but he cleared the obstacles on both sides. As a result, Darwin had achieved quite a coup. He had turned Lyell, the defender of a static model of the earth and England's most articulate critic of Lamarck, into a veritable prophet of evolution. Indeed he even managed to associate Lyell's idea of gradualism with the concept of natural selection, insisting that selection worked much like the action of erosion grinding away on a shoreline (95). Readers of Darwin's

chapters on geology can virtually hear Lyell crying in the wilderness. Darwin's formula of geological gradualism equals evolution and his oh-so-modest vision of evolutionary progress were tailor-made to Lyell's uniformitarian beliefs. Just as Darwin made Chambers a Christian, he made Lyell an evolutionist. All that was needed was for the grand old man to murmur his assent.

The question of progress affected all of Darwin's thoughts about geology, but it also played a role in his important concept of the struggle for existence. However, this progress was not, as Chambers had imagined it, a built-in feature of living forms. Rather it occurred as the indirect result of random variation and the unequal success of plants and animals in coping with their environment. In the Origin, Darwin explained that plants and animals do not enjoy the same opportunities to reproduce their kind. In practice, most members of any species perish before they get the opportunity. It was easy to demonstrate this reality; in the absence of checks on population, even slow-breeding creatures can increase their numbers geometrically. It is only a matter of time until they outstrip their food supply. In real life everyone is a competitor, and only a minority have the chance to survive and reproduce (62­68).

Naturalists had long been aware that life in a state of nature involved persistent conflict. Charles Lyell had written eloquently about the way that different species encourage or thwart one another. The examples were endless: a large tree might favor shade-loving species while excluding those that needed sun. Destructive insects might ravage some species and thereby make a place for others. As Lyell saw it, nature existed in a kind of rough balance with the expansion of each species checked by the activities of others. The balance was uneasy though, for changes in climate or the mysterious plagues of disease, parasites, and predators might at any time render a previously attractive situation untenable for one species or another. Ultimately, it was a zero-sum game with success for one species representing disaster for another (670­677).

An even more important influence on Darwin's idea of struggle was the theory of population advanced by the political economist Thomas Malthus. A social conservative, Malthus was reacting

against French ideas of social progress and, more immediately, against the British Poor Law, the principle welfare measure of his day (2:38­69). In his eyes, all efforts to improve the lot of the unfortunate through public charity were doomed to failure. No matter how much the poor might strive to improve themselves or how charitably their betters might sacrifice to assist them, unless their reproductive instincts were somehow checked, their numbers would inevitably press against the means of subsistence. As Malthus saw it, this was a general law of nature: "In plants and irrational animals, the view of the subject is simple. They are all impelled by a powerful instinct to the increase of their species;. . . and the superabundant effects are repressed afterwards by want of room and nourishment." (1:6)

The importance of this idea for evolution is unmistakable. Every effort to develop a theory of evolution by natural selection was based on Malthus's theory of population. Not only did Darwin rely on Malthus's theory, but so did his little-known forerunner Patrick Matthew and his rather better-known contemporary, Alfred Russel Wallace. Each of these men regarded the pressure of population as a force that subjected every natural organism to an existence of struggle, a struggle that in most cases would end unsuccessfully (McKinney 54­55; Mayr 494­501).

It is worth considering why the idea of natural selection did not occur to Charles Lyell. Like all educated men of his day, Lyell was certainly aware of Malthus's idea, and he was certainly aware of the struggle for existence among animals. The answer appears to be that Lyell thought of the struggle simply as a contest between species. A species might prosper in the struggle, or it might flounder and be driven to extinction, but members of the species essentially faced a common fate (Lyell 670­677). Darwin differed from Lyell in relating the concept of struggle to the idea of individual variation. He did not reject the idea of a struggle among species, but in considering the pressure of population, he was especially alert to its significance for the individual. Malthus helped him see that the tremendous capacity of all living creatures to reproduce put them at odds with others of their own kind. Since they all occupied the

Darwin illustrated the practical consequence of this competition by asking his readers to imagine a situation in which wolves were confronted with a change in the numbers of their customary prey. If swift animals, such as deer, became more important to these wolves, "the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected. . ." (90) In other words, selection constantly acts to adapt creatures to their environmental circumstances, allowing them to meet new challenges. However, selection does something more. In some cases, it is able to create entirely new creatures by making changes in the structure and function of their organs. For example, under the right circumstances it might have created bats by gradual modification of an animal rather like a flying lemur (180­181). Even more radically, it might have produced the first land-dwelling vertebrates by converting the swimbladder of a fish into a functioning lung (190­191).

Darwin's modification of Malthus's theory gave him a mechanism which explained the progress he thought he saw in nature. He made this explicit in his discussion of geology: "But in one particular sense the more recent forms must, on my theory, be higher than the more ancient; for each new species is formed by having had some advantage in the struggle for life over other and preceding forms." (337) Darwin might still join Lyell in expecting the discovery of Paleozoic mammals, but he was going to have some measure of progress, and Malthus had showed the way to a mechanism that would produce it. Intellectually, Malthus had provided the key to natural selection; personally, he had released Darwin from his intellectual tutelage under Charles Lyell. Structure and Distribution of Coral Reefs had indeed come half out of Lyell's brain; On the Origin of Species had not.

Robert Malthus was a fashionable thinker in England during the 1830s. His arguments had considerable weight in the highly contentious debates over the Poor Law. British Whigs, fed up with

increases in local taxes to support the old system of poor relief, had called on Malthus to justify restricting welfare to the inhabitants of the poor houses. The New Poor Law was actually passed before Darwin returned from the Beagle voyage, and we have no record of his attitude toward it; however, he was almost certainly exposed to Malthus's ideas from his occasional social contacts with Harriet Martineau, a prominent journalist who advocated Malthus's ideas. Charles's older brother Erasmus courted Martineau for a time, and they met at dinner on several occasions. Darwin's biographers, Adrian Desmond and James Moore, suggest that it was natural for him to adopt an idea that was so commonly represented in his social circle (153­4, 196­7, 201, 216­7, 264­7).

Desmond and Moore have made an important point about the social influences on Darwin, yet their case has its limits. As they themselves recognize, Darwin did not care for Martineau and was relieved when his brother did not marry her. There is really no scale for weighing Darwin's political beliefs against his scientific ambitions, particularly when his beliefs on the political issue in question are essentially unknown. Furthermore, regardless of his reasons for taking up Malthus's population theory, it seems likely that he thought about it differently as he began to recognize its full scientific potential. Malthus had no inkling of the evolutionary implications of his idea, and Darwin mentioned Malthus's name only once in the Origin of Species (63).

In effect, Darwin treated Malthus in much the same way that he had treated Robert Chambers. He acknowledged each man's contribution and then proceeded to ignore him. Compare his perfunctory nod to them with his lavish recognition of Charles Lyell. And why not? What he owed to Malthus was merely intellectual. What he owed to Lyell was deeply personal. The painstaking distinctions Darwin drew between his own position and that of Lyell were meant to establish his own independence while at the same time retaining Lyell's good will. He had to gently correct his old mentor while at the same time trying to convert him to a theory he had once rejected outright. Darwin's guarded comments about evolutionary progress testify eloquently to the difficulty of his task.

The Origin of Species transformed the intellectual landscape. Robert Chambers, hitherto regarded as an infidel, emerged as the pioneer of Christian evolutionism. Robert Malthus, previously a theoretician of welfare policy, became a proto-ecologist. And Charles Lyell, the bulwark against Lamarck's species transformism, was recostumed as the herald of natural selection. Darwin did not necessarily set out to do all of these things; his main goal was simply to make the best case he could for natural selection and avoid alienating potential supporters whenever possible. However, in constructing his argument for something new, he could not escape changing everything that was old. His book reshaped both science and scientific reputations. Today we remember numerous 19th century scientists as he presented them, not as they might have appeared to their contemporaries. Intellectual influence does not get any stronger than that.      ||

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William Montgomery has taught at Massachusetts College of Liberal Arts since 1986. He is currently an associate professor in the department of Interdisciplinary Studies and serves as acting chair. His primary interest is the history of science. He has written several articles on the history of evolutionary thought, and was an associate editor of the first three volumes of The Correspondence of Charles Darwin (Cambridge University Press, 1985­1987).