Nancy Armstrong, “On Charles Darwin’s The Descent of Man, 24 February 1871″


The Descent of Man, and Selection in Relation to Sex (1871) lays out how the principle of sexual selection could produce the splendid variety of animal life forms. This was Darwin’s way of explaining how human beings descended from animals. More to my point, however, this was Darwin’s way of accounting for the variations required before his principle of natural selection could promote some forms of life at the expense of others. Without the concept of “variation,” the theory of natural selection he proposed in The Origin of Species (1859) would not have been all that different from those of his competitors, save Alfred Russell Wallace. Nor could Darwin’s theory of evolution have achieved the extraordinary explanatory power it did. The Descent invites us to rethink this concept outside the gendered binaries of Victorian thought, so that it can challenge the primacy of natural selection.

Cameron photo of Darwin

Figure 1: Charles Darwin, photographed by Julia Margaret Cameron (1868)

A century and a half after the publication of The Origin of Species, readers—both expert and popular—still regard the process known as “natural selection” as the mainspring of Charles Darwin’s theory, the means by which he transformed what was then “natural history” into a modern “history of nature” (Foucault, Order 275). Writing on the “after” side of the historical fault line that Michel Foucault elaborates in The Order of Things, Darwin saw even the most comprehensive taxonomies of biological life as flawed by the discrepancy between the limits of human perception and the imperceptibly gradual but relentlessly dynamic process that created differences within and among the species. Virtually inseparable from the vital principle itself, “natural selection” directly challenged earlier accounts of natural historical change all the way from spontaneous creation to linear development. (See, for example, Cannon Schmitt, “On the Publication of Charles Darwin’s On the Origin of the Species, 1859.″) Natural selection redefined each and every species as but a temporary nodal point that sent out shoots which in turn sent out more shoots and developed branches in a haphazardly multidirectional manner wherever and so long as resources allowed. Multitudes either fell by the wayside or failed to materialize, not in the name of maintaining or perfecting the phenotype, but for the sake of producing new forms better able to avail themselves of resources and thus reproduce. At each step along the way, though, Darwin had to defend his conviction that natural selection was not a deadly force so much as a creative one and the primary cause of evolutionary change.

The Descent of Man comes close to assigning the winnowing process that Daniel C. Dennett famously names “Darwin’s dangerous idea” to a secondary role in Darwin’s powerful challenge to earlier theories of evolution (42). The reversal of his philosophical and scientific priorities in favor of sexual selection, however, was one for which he had prepared the way. In offering this alternative principle of selection, Darwin managed to solve his career-long problem of accounting for “variation” without dislodging natural selection as the dominant force of evolution. To formulate the principle of natural selection, he had to imagine a field of living organisms in which, as he put it, “[no] two individuals of the same race are quite alike” (860). So conceived, “variation” not only provided the given enabling him to imagine natural selection as a creative force, variation also raised a problem that natural selection could not adequately address—namely, how to account for the extraordinary diversity of forms that failed to become meaningful retroactively as traits that either had once or now distinguished species. Variation, as Darwin construed it, had to provide raw material without influencing the rate or direction of evolutionary change (Gould 137-55).

The following passage is one of many in which Darwin reminds his readers that it takes a surplus of biological possibilities, most of which never see the light of day, to produce the beauty of the common English garden:

We behold the face of nature bright with gladness, we often see a superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seed, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds or beasts of prey. (489-90)

What begins as a rather conventional personification of domesticated nature rapidly turns ugly, as Darwin catalogues the life that has been sacrificed in providing a “superabundance of food” for the diversity of species that presently cohabit a nineteenth-century garden with their human admirers. The prose gathers force as it moves past the limits of human perception, or what “we behold,” to envision the ongoing process of natural selection that has choreographed this moment of aesthetic amnesia. Darwin obviously staged the scene of nature’s abundance, so that he could expose the “face of nature” as only a fleeting moment in an ongoing process in which one element of nature feeds upon another. Thomas Malthus’s “principle of population” clearly casts its shadow over Darwin’s garden, as the “face of nature bright with gladness” blends into that of a human observer so enthralled with the apparent “superabundance of food” that he or she forgets that scarcity inevitably results from just this sense of plenty. Even so—indeed, because of the incipient violence of the scene—such scarcity enhances the sensory appeal of plentitude that induces the act of forgetting. Even here, however indirectly, Darwin calls attention to the sensual power of nature to distract us from the competitive struggle enabling the survival of some variations at the expense of others.

In his description of an English garden, Darwin pushes us beyond the rivalry that produces winners and losers in order to apprehend a nature that he had, in writing The Origin, come to understand in terms of the subtler difference between actual and potential manifestations. To reconceptualize biological life in these terms, he had to shift his focus away from both the living forms of life and the fossilized remains available to his observation and onto those variations that had either dropped out of view or had not yet materialized.  Like the life force itself, the logic of natural selection—its ability to transform seemingly meaningless differences into those identifying discrete species—depended on a system in which possibilities are not lost but instead accumulate as a surplus of potential differences available for selection. Let me map out in brief the evolution of the concept of variation from its secondary role throughout The Origin of Species (1859) to its full emergence in 1871, where it both shaped the participants in the melodrama that Darwin called “sexual selection” and materialized as the denouement.

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In his 1876 autobiography, Darwin claims that while traveling through the Southern Hemisphere, he read the first volume of Charles Lyell’s Principles of Geology (1830) by night and brought that reading to bear by day “on that which I have seen and am likely to see” (“Autobiography”  52, my emphases). Considering himself part of the picture and thus confined to a very limited moment of natural history, Darwin came to the obvious conclusion that he could never set eyes on the evidence required for purposes of explaining speciation as an ongoing process. He sought a theory that would give him a vantage point outside and above from which to survey the process in which he was immersed and so understand it as a systematic whole. To achieve this vantage point, he began at a very local level to read the curious specimens he observed as signs of invisible principles responsible for their extraordinary diversity. In the notebooks first published in 1839 and later known simply as The Voyage of the Beagle), one finds Darwin detaching biological life from the regional eco-systems of South America that Alexander von Humboldt had described and reorganizing that information as an independent system which contained its own principle of speciation. (On Darwin’s Beagle voyages, see Ian Duncan, “On Charles Darwin and the Voyage of the Beagle.”)

A description of a spectacle that kept him from crossing a river to map iconthe Pampas anticipates the conceptual shift I want to identify. “We were delayed,” Darwin recalls in The Voyage, “by some immense troops of mares, which were swimming the river. . . . A more ludicrous spectacle I never beheld than the hundreds and hundred of heads, all directed one way, with pointed ears and distended snorting nostrils, appearing just above the water like a great shoal of some amphibious animal” (85). A few pages later, we find him pausing to describe a second optical illusion in which this simile reverses itself and then materializes. What he saw as many individuals actually formed a single organism connected beneath the water’s surface. On first approaching this creature, he recalls seeing only “hundreds” of small tubular polyps “projecting like stubble, with the truncate end upwards, a few inches above the surface of the muddy sand” (106). Darwin rewrites the number “hundreds” as “thousands,” the instant he understands that no matter their number all the polyps “act by one movement” if any one of them is touched (107). This move from similitude (“like a great shoal of some amphibious animal”) to the materialization of the concept of interdependency in a giant colony of polyps provides a model that would allow Darwin to imagine any species as a single biological force field no matter how interdependent it might seem to be with the flora and fauna around it.

According to The Voyage, it was not many days later when he temporally expanded this same interpretive mechanism to include the fossil life exposed by geological upheavals of the Patagonian plain. No sooner had Darwin noted the features that the unearthed fossils shared with their present-day counterparts, than he began to imagine life as a vast network that not only connected the surface to deeper layers of the earth but also expanded outward within each layer to establish connections among geographically dispersed forms of biological life like the South American Rhea and the large flightless birds of Africa and map iconAustralia. To explain these links, Darwin had to transpose the figure of a colony of polyps onto a higher plane of abstraction where he could imagine biological life itself as such a system of interdependencies, one element of which was ultimately engaged in a reciprocally defining relationship with all others. By what principle had life expanded and diversified to form this all-encompassing, multi-dimensional system? Darwin’s ability to account for speciation depended on his system’s capacity to diversify as it spread outward geographically, both encircling the earth, according to Malthus’s principle of population, and piling up in layers that marked spans of deep time, as Lyell had argued. Let any element of such a system be altered, and new forms would arise to take advantage of that alteration by outstripping their progenitors.

In a 56-page “Sketch” written 3 years after the publication of The Voyage, Darwin claimed that he was now ready to fill in “the pages missing,” for lack of fossil evidence, from Lyell’s account of earlier forms of life that had not survived into the present (16). Rather than dig for more fossils, he would use missing data as evidence to support the principle that new species came about as the parent type underwent any number of extremely slow and almost imperceptible changes, with the result that “the horse [ultimately] has the same ancestor as the tapir and elephant” (16). In response to the obvious question, “What evidence of this is there?,” he proceeded to argue that the absence of proof itself constituted proof that transitional biological forms had once existed. To put it another way, ruptures of the continuity of visible information testified to the gradual process of speciation. His reasoning goes something like this: If the ancestors common to different species did indeed “fall between [those] species,” then only the traces in later species would testify to the existence of those missing ancestors (16). In attributing the lack of fossil evidence to the slow displacement of parent forms by transitional generations, Darwin knew he had raised more questions than he answered: How, on the one hand, were those transitional forms eradicated, and whence, on the other hand, came the traits that allowed new varieties to displace them? In order for the concept of natural selection to behave as the creative force he insisted it was, Darwin had to develop a concept that could answer both these questions at once.

Paradoxically, the lack of evidence testifying to the transitional forms of life linking one robust species to its replacements provided both inspiration and evidence for his breakthrough hypothesis: All life was engaged in a struggle for existence, and in this struggle only certain variations of a former species had succeeded in reproducing their distinctive feature or features over time; the less competitive variations did not last as long. With this insight, Darwin had all but assembled what readers then and now consider the overarching logic governing the transformation and perpetuation of life forms. Darwin’s 1842 “Sketch” described a process—not yet named “natural selection”—that selectively eliminated the numbers that any species inevitably produced over and above the resources necessary to sustain them. When reproduced over many generations under conditions of scarcity, he reasoned, certain minute deviations from the parent form would give their bearers a leg up in the competition for resources. Several such minor monsters inevitably supplanted the parent to be replaced in turn by a process that works more like the spread of crab grass than the growth of a tree.

Darwin spent the years between 1842 and 1859 supplementing the already abundant observations for The Voyage of the Beagle with material from fellow naturalists across the globe, the results of his own experimentation with plants, various and strange research projects undertaken by contemporary scientists, and anecdotes gleaned from fellow travelers and local breeders of domestic animals. Save for demonstrating by means of what seem like countless examples that natural selection could account for every observable life form, present and past, on the planet, Darwin’s theory of the origin of species was complete nearly 20 years before it appeared in print. Or so critical commonplace would have it. But was it, I wonder, only because he was skittish about the reception of a theory that lacked a first and final cause—thus metaphysical grounding—that Darwin hesitated for so long to publish his theory of evolution?

* * *

I like to think that at some level he knew he was missing a piece of the puzzle, something more basic to his logic than evidence yet to be discovered in the interstices between identifiable species. In order for his principle of natural selection to do the work of winnowing out the minor characters of natural history so that a succession of major characters could emerge, Darwin first had to imagine a constant and copious supply of material from which the most useful traits could be selected. Thus before he imagined selection as a creative process internal to the biological system he was developing, he had to identify a source of formal deviations not yet locked into platonic categories or assigned to specialized uses. Of Darwin’s many commentators, Stephen Jay Gould offers perhaps the most concise description of the conceptual tightrope Darwin had to walk in coming up with such a source: “First and foremost, variation must exist in sufficient amounts, for natural selection can make nothing, and must rely on the bounty thus provided; but variation must not be too florid or showy either, lest it become the creative agent of change all by itself” (141). Were Darwin to err in either direction, he would be stepping into the trap of substituting a new cause extrinsic to the biological system for an older and traditional one. In the chapter of The Origin immediately following his exposition of “Natural Selection,” Darwin proposed a source of surplus differences intrinsic to his system.

Having shown that features of extinct species sometimes returned to advantage in new species, he could argue that natural selection not only eliminated life forms but simultaneously also conserved their unused parts. As he put it in his chapter of The Origin titled “Laws of Variation,” “natural selection will always succeed in the long run in reducing and saving every part of the organisation, as soon as it is rendered superfluous, without by any means causing some other part to be largely developed in a corresponding degree” (545). If the natural selection produced a surplus of residual traits, he reasoned, then every species was an assemblage of part objects, each capable of developing independently. Rather than acting holistically on behalf of a species or even on behalf of some extraordinary member of a species, the winnowing process acted on behalf of each species and all its members only by acting “on each part of each being, solely through and for its advantage” (545). In solving one problem, however, Darwin—like any thinker of his magnitude—raised another. In order to store the residual features of each species in its particular members, he had to break down what traditionally appeared to be the constitutive parts of the biological world into part objects capable of forming new and unpredictable combinations of available traits, not all of which would actually give that organism—and eventually a species—an edge. If natural selection divided the winners from the losers, why was it so often the apparently non-advantageous features that came to mark a species (546)? In this respect, Darwin proved himself better than his critics at interrogating his theory, and he knew that to be so creative, nature could not have relied on natural selection alone. To the contrary, he recognized that nature must have also observed a principle something like James Clerk Maxwell’s entropy-defying demon or the bricolage practiced by Charles Dickens’s Wemmick, whose castle made of historical debris was cited by Claude Lèvi-Strauss as the very example of cultural creativity.

In writing The Origin of Species, Darwin had come to see that the precision with which natural selection worked over many generations to hone and polish the particular variations enabling the survival of certain species was equaled by the carelessness with which natural selection allowed non-essential, or “rudimentary,” parts to live on in each of its members. Paradoxically, the survival of such features was, in Darwin’s words, “owing to their uselessness, and therefore to natural selection having no power to check deviations in their structure” (546). Rather than place each form of life within a line of descent determined by the functionalism of greater fitness, Darwin saw each of these uncommitted features as having the potential to divert that line into competing variations. These features would prove to be diversions in more than one sense of the word.

To counter the idea that each species was an integrated whole on its way to becoming another integrated whole or else suffering extinction, Darwin made each member of a species into a little archive or holding environment wherein “rudimentary parts are left to the free play of the various laws of growth, to the effects of long-continued disuse, and to the tendency of reversion” (546). From this field of possibilities, he imagined new branches of development. Throughout The Origin of the Species, the material that he marshaled in support of his theory of natural selection—topsy-turvy pigeons, little teams of apian architects, dogs capable of interspecies affect—diverted Darwin’s attention wherever his examples threatened the logic of natural selection. His fascination with this evidence so regularly overwhelmed his attempt to systematize it that he may well have sensed that the principle of natural selection needed some help if it were to explain how this veritable circus of performances came into being, much less account for human difference.

Or so we might infer from the fact that in concluding his next big book, The Variation of Animals and Plants under Domestication (1868), Darwin initially intended to include a chapter on the animal ancestry of human beings. When he found that chapter growing overlong, however, he turned it into a separate essay that eventually expanded to become a separate book. Published in 1871, The Descent of Man, and Natural Selection in Relation to Sex, a book half again as long as The Origin of Species, took up the challenge to natural selection Darwin raised in The Origin: If natural selection inevitably eliminated the less efficient variations, he asked, why was it that no two individuals were exactly the same? Yes, such a radical degree of minor variation certainly indicated that man was highly evolved, though woefully unfit to survive under natural conditions. But did this manifest unfitness necessarily make the human species an exception to natural selection rather than its most exalted product? Darwin read the mature and fetal forms of the human body for signs of its biological heritage, and he concluded that virtually all distinctively human traits, including those traditionally testifying to our capacity to transcend biology, arose from within a preexisting biological system. To support the autogenic claims of his theory, however, he had to identify a mechanism for selecting benign and apparently useless, even potentially disadvantageous traits for posterity. Once again, as in The Origin, Darwin piled up countless examples from a wide range of species to illustrate his principle, but here, in The Descent of Man, the surplus of forms supported rather than confounded the alternative logic of selection he proposed. In contrast to natural selection, we might say, sexual selection allowed the creative exuberance bottled up in his negative description of an English garden to express itself.

Consider an account related by a man who tried to mate a female zebra with a donkey. Darwin put a great deal of stock in the fact that the zebra allegedly rejected “the addresses of the ass until he was painted so as to resemble a zebra” (1187). Only then did she welcome those addresses. He regards this female behavior as an instance of “instinct excited by mere colour, which had so strong an effect as to get the better of everything else” (1187). As for the male (Darwin finishes this thought), the zebra’s being “an animal somewhat similar to himself, was sufficient to arouse him” (1187). Here, less concerned with where the zebra’s stripes came from or how they might once have aided its survival, he could show how such an apparently “useless” feature might have eluded natural selection only to be plucked by the female from the curiosity shop of variant features and made into a reproductive incentive. What was arguably superfluous in the competitive struggle among males might, in this way, suddenly become the means for a variation to emerge and consolidate itself as a new species. By promoting a feature that simply happens to attract a female by means of its sensual appeal, sexual selection gave Darwin a way of accounting for the flamboyant extremes of nature, where, on its own, natural selection would ultimately yield only those characteristics that had proved practical in an arena defined by male-male competition.

* * *

Thus we have two mechanisms of selection: one weeding out what has no apparent value in competitive terms but, paradoxically, conserving those superfluous features within the archive of each living being; the other by what might seem like chance encounters selecting from among a plenitude of otherwise useless traits precisely what diverted nature from the practical advantage to be gained through the selective process. In a system organized by these contrary but ultimately collaborative principles, new characteristics would arise wherever material conditions forced some renegotiation of the difference between those features discarded as useless and those that proved advantageous to the organism’s survival. If in The Descent of Man, as in The Origin of Species, the principle of sexual selection strikes us as loose and whimsical in comparison to the rigors of natural selection, that is largely due to Darwin’s habit, in the later work, to characterize sexual selection as feminine in contrast to the masculine principle of natural selection.

I think it is time to put aside the gender inflection that marks his thinking as Victorian and reassess the unique and decisive role of sexual selection—the capacity of some features to capture the attention of the female of the species who then responds by selecting the males in whom that feature is prominent. Let us assume that the selective process that gave the zebra his dashing stripes or the peacock his extravagant tail is no more arbitrary than the force that made the bear’s claw and tiger’s tooth. Where the tooth and claw rank high in narrowly utilitarian terms, the feathered tail and flashy stripe may seem to lack any practical function. But let us also keep in mind that they do so only if we insist on opposing beauty to usefulness, mapping sensual attraction vs. competition onto that opposition, and then overvaluing the agency of the two latter terms. If certain variations had not been selected for their sheer sensuality, Darwin’s garden might be as dull as it is efficient, all extreme and extraneous variations having been culled by the mindless algorithm called “natural selection.” Elizabeth Grosz pushes this argument further, claiming that “if species reproduced only themselves or [if they did so] in ever-diminishing numbers, natural selection would be unable to weed out the less fit and provide space for the selection and proliferation of the more fit, effectively preventing selection” (44). Were natural selection the only game in town, she reasons, Darwin’s entire system would eventually wind down.

To address the question of variation’s source and the role it plays in relation to Darwin’s twin theories of selection, it is necessary to pursue this line of thinking yet further dialectically. To do so, we must ask whether it is enough to undo the gender ideology of Darwin’s century and grant sexual selection logical priority over natural selection. What explanatory advantage do we gain by supplementing the dynamic of competitive elimination with a dynamic of sensual appeal in order to account for the female zebra’s attraction to a mate wearing the archaic stripes of the equine species? Not quite enough would be my answer. In answering the question of where new variations come from, the elevation of sexual selection over natural selection only throws us back on the archival, or “rudimentary,” parts of the organism that Darwin elaborated in chapter V of The Origin of Species called “Laws of Variation.” Contained within the organism itself was not only the material for change but also the propensity to do so. Unique in itself, each member of every species houses a superabundance of residual formal options, among which Darwin designated the “rudimentary” features especially prone to combine with other residual features and form countless slight variations from which any number of slight variations might emerge and initiate the long, slow, and frequently diverted process of speciation. Though statistically incalculable, Darwin’s theory nevertheless confined all this wonderful variety to a theoretical vector anchored to an imaginary point or points of origin within the system of biological life he formulated in The Origin of Species. Must we really leave it at that?

As Foucault reminds us, any author of Darwin’s extraordinary influence will have said much more than he means to, leaving it to future readers to tease out that unrealized potential (Foucault “Author”). By nudging it into dialectic, we can use The Descent to think ourselves out of a system that expands from within according to uniform principles. To pursue such a line of reasoning, we need to reconsider an aspect of variation occluded by the chiaroscuro of Darwin’s garden. In stressing the cost of that garden in terms of reducing what he describes as a “superabundance” of life, Darwin neglects to make the obvious point that—as his own figural language here suggests—something rather like aesthetic selection has done a lot to create the rich diversity of life forms that make up “the face of nature bright with gladness” in his garden. By using this term I am not referring only to the gardener’s selection or even to his possible experiments with hybridization, neither of which, as Darwin consistently argued, were likely to produce variations that could disrupt the repetition of the same by coming up with something new. My use of the term “aesthetic selection” is meant to shake our definition of sexual selection free of the presupposition that it, too, would aim at reproducing the same were the female not momentarily distracted by the donkey’s lack of stripes. This definition of the source of her attraction allows Darwin to subsume sexual selection in natural selection and designate the former as relatively unimportant to each partner’s natural inclination toward self-replication.

Familiarity with Victorian literature not only attunes one to the figural dimension of the natural world that Darwin assembled largely in words but also licenses her to expand the notion of sexual attraction accordingly. If we reconsider the principle of attraction prompting the zebra’s preference for stripes, it could well be that the breeder’s experiment in hybridization did not fool the female zebra so much as expose the limits of that breeder’s reasoning as to why she found a painted donkey more appealing than a plain one. Like so many of the little romances from animal life that make up the bulk of the examples in The Descent of Man, Darwin uses this one to demonstrate that the female of the species has the power to select a mate (men being “generally willing to accept any female”) and does so on a frivolous basis—though with inadvertently innovative results (1010). Supporting both these assumptions is the yet more basic though equally arbitrary assumption that the females of each species actually want to reproduce their kind. The aesthetic drift of The Descent of Man argues otherwise.

Darwin frequently supported his theoretical principles by drawing comparisons with domestic breeding, and The Descent is no exception. To direct our attention to the splendid colors, curious appendages, and intricate mating habits of the male of the species as well as to the comparative drabness of the female, Darwin asks us “to suppose [as a general principle] that the females do the choosing and generally prefer, or are most excited by the more brilliant males” (1007). Well into his argument, he asks us to think of the domestic breeder as “loosely analogous” to the female zebra in that he, too, “continues for a long time choosing the most pleasing or useful individuals, without any wish to modify the breed,” despite the fact that this modification is what he accomplishes (1244). To maintain this analogical relationship between female zebra and breeder, we must concede that her attraction to frivolous differences is probably as true of him as well and so perhaps of the male of the species generally—hence the curious breeds of dogs and pigeons produced by domestic breeding. If so, then to be faithful to our analogy, we must ask ourselves whether the female zebra was not duped so much as “excited” by the novelty of a painted donkey.

In entertaining this possibility, we have to ask if the ass was really as practical as Darwin concludes from this experiment with hybridization. Perhaps that ass was as attracted to the novelty of her stripes as she was to the painted donkey. If we are willing to take Darwin at his word and think of the breeder as “loosely analogous” to the zebra in this respect, we must conclude that he was just as attracted to difference as she was—as he can have no practical reason for mating a zebra with a donkey. When acknowledged as the precondition for a selection motivated by an attraction to difference over and above sameness, variation assumes a co-dependent, if not primary role over natural selection.

published September 2013

Nancy Armstrong is Gilbert, Louis, and Edward Lehrman Professor of English at Duke University. Her books include Desire and Domestic Fiction: A Political History of the Novel, (with Leonard Tennenhouse) The Imaginary Puritan: Literature, Intellectual Labor, and the Origins of Personal Life, Fiction in the Age of Photography: The Legacy of British Realism, and How Novels Think: The Limits of Individualism, 1719-1900. She edits the journal Novel: A Forum on Fiction.


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