Editing On the Origin of Species (section)

==Structure, style, and themes==
===Nature and structure of Darwin's argument===
Darwin's aims were twofold: to show that species had not been separately created, and to show that [[natural selection]] had been the chief agent of change.<ref>{{harvnb|Darwin|1871|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F937.1&pageseq=165 152]}}</ref> He knew that his readers were already familiar with the concept of transmutation of species from ''[[Vestiges of the Natural History of Creation|Vestiges]]'', and his introduction ridicules that work as failing to provide a viable mechanism.<ref name=sec/> Therefore, the first four chapters lay out his case that selection in nature, caused by the struggle for existence, is analogous to the selection of variations under domestication, and that the accumulation of adaptive variations provides a scientifically testable mechanism for evolutionary [[speciation]].<ref>{{harvnb|Quammen|2006|pp=183–188}}</ref><ref name=bowl180>{{harvnb|Bowler|2003|pp=180–181}}</ref>

Later chapters provide evidence that evolution has occurred, supporting the idea of branching, adaptive evolution without directly proving that selection is the mechanism. Darwin presents supporting facts drawn from many disciplines, showing that his theory could explain a myriad of observations from many fields of natural history that were inexplicable under the alternative concept that species had been individually created.<ref name=bowl180/><ref>{{Harvnb|Quammen|2006|pp=190, 200–201}}</ref><ref>{{Harvnb|Larson|2004|pp=88–89}}</ref> The structure of Darwin's argument showed the influence of [[John Herschel]], whose philosophy of science maintained that a mechanism could be called a ''vera causa'' (true cause) if three things could be demonstrated: its existence in nature, its ability to produce the effects of interest, and its ability to explain a wide range of observations.<ref>{{harvnb|Darwin|Costa|2009|p=xvii}}</ref> This reflected the influence of [[William Whewell]]'s idea of a consilience of inductions, as explained in his work ''Philosophy of the Inductive Sciences'', where if you could argue that a proposed mechanism successfully explained various phenomena you could then use those arguments as evidence for that mechanism.<ref>{{harvnb|Ruse|2009|pp=22–23}}</ref>

===Literary style===
The ''Examiner'' review of 3 December 1859 commented, "Much of Mr. Darwin's volume is what ordinary readers would call 'tough reading;' that is, writing which to comprehend requires concentrated attention and some preparation for the task. All, however, is by no means of this description, and many parts of the book abound in information, easy to comprehend and both instructive and entertaining."<ref name=sec/><ref>{{Harvnb|Crawford|1859}}</ref>

While the book was readable enough to sell, its dryness ensured that it was seen as aimed at specialist scientists and could not be dismissed as mere journalism or imaginative fiction. Though Richard Owen did complain in the Quarterly Review that the style was too easy for a serious work of science.<ref>{{harvnb|Ruse|2009|p=18}}</ref> Unlike the still-popular ''Vestiges'', it avoided the narrative style of the historical novel and cosmological speculation, though the closing sentence clearly hinted at cosmic progression. Darwin had long been immersed in the literary forms and practices of specialist science, and made effective use of his skills in structuring arguments.<ref name=sec>{{harvnb|Secord|2000|pp=508–511}}</ref> [[David Quammen]] has described the book as written in everyday language for a wide audience, but noted that Darwin's literary style was uneven: in some places he used convoluted sentences that are difficult to read, while in other places his writing was beautiful. Quammen advised that later editions were weakened by Darwin making concessions and adding details to address his critics, and recommended the first edition.<ref>{{harvnb|Quammen|2006|pp=176–181}}</ref> James T. Costa said that because the book was an abstract produced in haste in response to Wallace's essay, it was more approachable than the big book on natural selection Darwin had been working on, which would have been encumbered by scholarly footnotes and much more technical detail. He added that some parts of ''Origin'' are dense, but other parts are almost lyrical, and the case studies and observations are presented in a narrative style unusual in serious scientific books, which broadened its audience.<ref>{{harvnb|Darwin|Costa|2009|p=ix}}</ref>

=== Human evolution ===
From his early transmutation notebooks in the late 1830s onwards, Darwin considered [[human evolution]] as part of the natural processes he was investigating,<ref name=JC_51 /> and rejected divine intervention.<ref>{{harvnb|Browne|2007|p=42}}, quoting [http://darwin-online.org.uk/content/frameset?pageseq=172&itemID=CUL-DAR122.-&viewtype=text Darwin, C. R. Notebook C] (February to July 1838) pp. 196–197 "Man in his arrogance thinks himself a great work worthy the interposition of a deity, more humble & I believe truer to consider him created from animals."</ref> In 1856, his "big book on species" titled ''[[Natural Selection (manuscript)|Natural Selection]]'' was to include a "note on Man", but when Wallace enquired in December 1857, Darwin replied; "You ask whether I shall discuss 'man';—I think I shall avoid whole subject, as so surrounded with prejudices, though I fully admit that it is the highest & most interesting problem for the naturalist."<ref>{{Harvnb|Desmond|Moore|1991|pp=412–441, 457–458, 462–463}}<br />{{harvnb|Desmond|Moore|2009|pp=283–284, 290–292, 295}}</ref><ref name=Letter2192>{{cite web |url=http://www.darwinproject.ac.uk/DCP-LETT-2192 |title= Letter 2192 – Darwin, C. R. to Wallace, A. R., 22 December 1857 |publisher=Darwin Correspondence Project }}</ref>
On 28 March 1859, with his manuscript for the book well under way, Darwin wrote to Lyell offering the suggested publisher [[John Murray III|John Murray]] assurances "That I do not discuss origin of man".<ref name="Letter 2437" />{{sfn|Desmond|Moore|2009|p=306}}

In the final chapter of ''On the Origin of Species'', "[[#Concluding remarks|Recapitulation and Conclusion]]", Darwin briefly highlights the human implications of his theory:

<blockquote>"In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history."<ref>{{Harvnb|Darwin|1871|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=506 488]}}</ref></blockquote>

Discussing this in January 1860, Darwin assured Lyell that "by the sentence [Light will be thrown on the origin of man and his history] I show that I believe man is in same predicament with other animals.<ref name="Letter 2647">{{cite web |url=http://www.darwinproject.ac.uk/DCP-LETT-2647 |title= Letter 2647 – Darwin, C. R. to Charles Lyell, 10 January (1860) |publisher=Darwin Correspondence Project|access-date=18 September 2017}}</ref> Many modern writers have seen this sentence as Darwin's only reference to humans in the book;<ref name=JC_51 /> [[Janet Browne]] describes it as his only discussion there of human origins, while noting that the book makes other references to humanity.<ref>For example, {{harvnb|Browne|2002|p=60}}, "In this book, he was completely silent on the subject of human origins, although he did refer in several places to mankind as an example of biological details. The only words he allowed himself—and these out of a sense of duty that he must somewhere refer to human beings–were gnomic in their brevity. 'Light will be thrown on the origin of man and his history'."</ref>

Some other statements in the book are quietly effective at pointing out the implication that humans are simply another species, evolving through the same processes and principles affecting other organisms. For example,<ref name=JC_51>{{cite book |last= Carroll |first= Joseph |date= 2003 |title= On the Origin of Species / Charles Darwin |url= https://books.google.com/books?id=eTfRotZTXI0C&pg=PA51 |publisher= Broadview Press |pages= 51–52 |isbn= 1-55111-337-6 |author-link= Joseph Carroll (scholar)|quote=Following Darwin's lead, most commentators cite this one passage as the only reference to man in the ''Origin'', but they thus overlook, as did Darwin himself, two sentences that are, in their own quiet way, even more effective.}}</ref> in Chapter III: "Struggle for Existence" Darwin includes "slow-breeding man" among other examples of [[Malthusian trap|Malthusian population growth]].<ref>{{Harvnb|Darwin|1859|p=[http://darwin-online.org.uk/content/frameset?pageseq=79&itemID=F373&viewtype=text 64]}}, Quote: "There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing room for his progeny."</ref> In his discussions on [[Morphology (biology)|morphology]], Darwin compares and comments on bone structures that are [[Homology (biology)|homologous]] between humans and other mammals.<ref>{{Harvnb|van Wyhe|2008}}<br/>{{harvnb|Darwin|1859|p=[http://darwin-online.org.uk/content/frameset?pageseq=452&itemID=F373&viewtype=text 434]}}, Quote: "What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include the same bones, in the same relative positions?"<br/>{{harvnb|Darwin|1859|p=[http://darwin-online.org.uk/content/frameset?pageseq=497&itemID=F373&viewtype=text 479]}}, Quote: "The framework of bones being the same in the hand of a man, wing of a bat, fin of the porpoise, and leg of the horse … at once explain themselves on the theory of descent with slow and slight successive modifications."</ref>

Darwin's early notebooks discussed how non-adaptive characteristics could be selected when animals or humans chose mates,<ref>Darwin, C. R. Notebook C, CUL-DAR122.- Transcribed by Kees Rookmaaker. (Darwin Online), notes from de Beer, Gavin ed. 1960. Darwin's notebooks on transmutation of species. Part II. Second notebook [C] (February to July 1838). ''Bulletin of the British Museum (Natural History)''. Historical Series 2, No. 3 (May): pp. [http://darwin-online.org.uk/content/frameset?pageseq=5&itemID=F1574b&viewtype=text 79]</ref> with [[Race (human classification)|races of humans]] differing over ideas of beauty.<ref>{{harvnb|Desmond|Moore|2009|pp=139–141}}, quotes "our acquiring the <u>instinct</u> one notion of beauty & negroes another" from Darwin, C. R. Notebook M : [Metaphysics on morals and speculations on expression (1838)]. CUL-DAR125.- Transcribed by Kees Rookmaaker, edited by Paul Barrett. (Darwin Online, p. [http://darwin-online.org.uk/content/frameset?pageseq=30&itemID=CUL-DAR125.-&viewtype=text 32]</ref> In his 1856 notes responding to [[Robert Knox (surgeon)|Robert Knox]]'s ''The Races of Man: A Fragment'', he called this effect [[sexual selection]].{{sfn|Richards|2017|pp=[https://books.google.com/books?id=PAF2DgAAQBAJ&pg=PA315 315], [https://books.google.com/books?id=PAF2DgAAQBAJ&pg=PA324 323–324]|ps=. Darwin concluded his notes on the ''Races of Men'': 'Fuegians & Brazil, climate & habits of life so different good instance of how fixed races are, in face of very different external conditions. The slowness of any changes explained by constitutions selection & sexual selection'.}} He added notes on sexual selection to his "big book on species", and in mid-1857 he added a section heading "Theory applied to Races of Man", but did not add text on this topic.<ref>{{harvnb|Desmond|Moore|2009|pp=290–291}} Stauffer, R. C. ed. 1975. ''Charles Darwin's Natural Selection; being the second part of his big species book written from 1856 to 1858.'' Cambridge: Cambridge University Press. [http://darwin-online.org.uk/content/frameset?pageseq=228&itemID=F1583&viewtype=text p. 213] Chapter Vi On Natural Selection first draft, completed on 31 March 1857, [The outline of this original form of the chapter appears in the original table of contents] "63 [pencil addition] Theory applied to Races of Man."</ref>

In ''On the Origin of Species'', Chapter VI: "Difficulties on Theory", Darwin mentions this in the context of "slight and unimportant variations":<ref name="OtOOS 197">{{Harvnb|Darwin|1859|pp=[http://darwin-online.org.uk/content/frameset?pageseq=215&itemID=F373&viewtype=text 197–199]}}</ref>

<blockquote>I might have adduced for this same purpose the differences between the races of man, which are so strongly marked; I may add that some little light can apparently be thrown on the origin of these differences, chiefly through sexual selection of a particular kind, but without here entering on copious details my reasoning would appear frivolous."<ref name="OtOOS 197" /></blockquote>

When Darwin published ''[[The Descent of Man, and Selection in Relation to Sex]]'' twelve years later, he said that he had not gone into detail on human evolution in the ''Origin'' as he thought that would "only add to the prejudices against my views". He had not completely avoided the topic:<ref name="DOM 1">{{Harvnb|Darwin|1871|p=[http://darwin-online.org.uk/content/frameset?pageseq=14&itemID=F937.1&viewtype=text 1]}}, Quote: "During many years I collected notes on the origin or descent of man, without any intention of publishing on the subject, but rather with the determination not to publish, as I thought that I should thus only add to the prejudices against my views."</ref>

<blockquote>It seemed to me sufficient to indicate, in the first edition of my "Origin of Species," that by this work "light would be thrown on the origin of man and his history;" and this implies that man must be included with other organic beings in any general conclusion respecting his manner of appearance on this earth.<ref name="DOM 1" /><ref>See also {{Harvnb|Darwin|1958|pp=[http://darwin-online.org.uk/content/frameset?pageseq=136&itemID=F1497&viewtype=text 130–131]}}, Quote: "My ''Descent of Man'' was published in Feb. 1871. As soon as I had become, in the year 1837 or 1838, convinced that species were mutable productions, I could not avoid the belief that man must come under the same law. Accordingly I collected notes on the subject for my own satisfaction, and not for a long time with any intention of publishing. Although in the ''Origin of Species,'' the derivation of any particular species is never discussed, yet I thought it best, in order that no honourable man should accuse me of concealing my views, to add that by the work in question 'light would be thrown on the origin of man and his history.' It would have been useless and injurious to the success of the book to have paraded without giving any evidence my conviction with respect to his origin."</ref></blockquote>

He also said that he had "merely alluded" in that book to sexual selection differentiating human races.<ref>{{Harvnb|Darwin|1871|pp=[http://darwin-online.org.uk/content/frameset?pageseq=17&itemID=F937.1&viewtype=text 4–5]}}. Quote: "During many years it has seemed to me highly probable that sexual selection has played an important part in differentiating the races of man; but in my 'Origin of Species' (first edition, p. 199) I contented myself by merely alluding to this belief."</ref>