Editing On the Origin of Species (section)

===Impact on the scientific community===
{{See also|History of evolutionary thought}}

Scientific readers were already aware of arguments that species changed through processes that were subject to [[Physical law|laws of nature]], but the transmutational ideas of Lamarck and the vague "law of development" of ''Vestiges'' had not found scientific favour. Darwin presented [[natural selection]] as a scientifically testable mechanism while accepting that other mechanisms such as [[inheritance of acquired characters]] were possible. His strategy established that evolution through natural laws was worthy of scientific study, and by 1875, most scientists accepted that evolution occurred but few thought natural selection was significant. Darwin's scientific method was also disputed, with his proponents favouring the [[empiricism]] of [[John Stuart Mill]]'s ''[[A System of Logic]]'', while opponents held to the idealist school of [[William Whewell]]'s ''Philosophy of the Inductive Sciences'', in which investigation could begin with the intuitive idea that species were fixed objects created by design.<ref>{{harvnb|Bowler|2003|pp=179–180, 197–198}}</ref> Early support for Darwin's ideas came from the findings of field naturalists studying [[biogeography]] and ecology, including [[Joseph Dalton Hooker]] in 1860, and [[Asa Gray]] in 1862. [[Henry Walter Bates]] presented research in 1861 that explained [[Batesian mimicry|insect mimicry]] using natural selection. [[Alfred Russel Wallace]] discussed evidence from his [[Malay Archipelago]] research, including an 1864 paper with an evolutionary explanation for the [[Wallace line]].<ref>{{harvnb|Bowler|2003|pp=183–184, 189}}</ref>

[[File:Huxley - Mans Place in Nature.jpg|left|300px|thumb|[[Thomas Henry Huxley|Huxley]] used illustrations to show that humans and apes had the same basic skeletal structure.<ref>{{harvnb|Bowler|2003|p=208}}</ref>]]

Evolution had less obvious applications to [[anatomy]] and [[morphology (biology)|morphology]], and at first had little impact on the research of the anatomist [[Thomas Henry Huxley]].<ref name="Bowler184-185">{{harvnb|Bowler|2003|pp=184–185}}</ref> Despite this, Huxley strongly supported Darwin on evolution; though he called for experiments to show whether natural selection could form new species, and questioned if Darwin's [[gradualism]] was sufficient without [[Saltation (biology)|sudden leaps]] to cause [[speciation]]. Huxley wanted science to be secular, without religious interference, and his article in the April 1860 ''[[Westminster Review]]'' promoted [[naturalism (philosophy)|scientific naturalism]] over natural theology,<ref>{{harvnb|Browne|2002|pp=105–106}}</ref><ref name=westminster>{{harvnb|Huxley|1860}}</ref> praising Darwin for "extending the domination of Science over regions of thought into which she has, as yet, hardly penetrated" and coining the term "[[Darwinism]]" as part of his efforts to secularise and professionalise science.<ref>{{harvnb|Bowler|2003|p=184}}</ref> Huxley gained influence, and initiated the [[X Club]], which used the journal ''[[Nature (journal)|Nature]]'' to promote evolution and naturalism, shaping much of late-Victorian science. Later, the German morphologist [[Ernst Haeckel]] would convince Huxley that comparative anatomy and [[paleontology|palaeontology]] could be used to reconstruct [[phylogenetics|evolutionary genealogies]].<ref name="Bowler184-185"/><ref>{{harvnb|Larson|2004|p=108}}</ref>

The leading naturalist in Britain was the anatomist [[Richard Owen]], an idealist who had shifted to the view in the 1850s that the history of life was the gradual unfolding of a divine plan.<ref>{{harvnb|Bowler|2003|pp=124–126}}</ref> Owen's review of the ''Origin'' in the April 1860 ''Edinburgh Review'' bitterly attacked Huxley, Hooker and Darwin, but also signalled acceptance of a kind of evolution as a [[teleology|teleological]] plan in a continuous "ordained becoming", with new species appearing by natural birth. Others that rejected natural selection, but supported "creation by birth", included the [[George Campbell, 8th Duke of Argyll|Duke of Argyll]] who explained beauty in plumage by design.<ref>{{harvnb|Desmond|Moore|1991|pp=490–491, 545–547}}</ref><ref>{{harvnb|Secord|2000|p=512}}</ref> Since 1858, Huxley had emphasised anatomical similarities between apes and humans, contesting Owen's view that humans were a separate sub-class. Their disagreement over human origins came to the fore at the [[British Association for the Advancement of Science]] meeting featuring the legendary [[1860 Oxford evolution debate]].<ref name=oed>{{Harvnb|Lucas|1979}}</ref><ref>{{Harvnb|Desmond|Moore|1991|pp=464–465, 493–499}}</ref> In two years of acrimonious public dispute that [[Charles Kingsley]] satirised as the "[[Great Hippocampus Question]]" and parodied in ''[[The Water-Babies, A Fairy Tale for a Land Baby|The Water-Babies]]'' as the "great hippopotamus test", Huxley showed that Owen was incorrect in asserting that ape brains lacked a structure present in human brains.<ref>{{harvnb|Browne|2002|pp=160–161}}</ref> Others, including [[Charles Lyell]] and [[Alfred Russel Wallace]], thought that humans shared a common ancestor with apes, but higher mental faculties could not have evolved through a purely material process. Darwin published his own explanation in the ''[[Descent of Man]]'' (1871).<ref>{{harvnb|Bowler|2003|pp=208–211, 214–216}}</ref>

====Impact outside Great Britain====
[[File:Pedigree of man (Haeckel 1874).jpg|thumb|right|Haeckel showed a main trunk leading to mankind with minor branches to various animals, unlike Darwin's branching evolutionary tree.<ref name="Bowler190_191" />]]

The German physiologist [[Emil du Bois-Reymond]] converted to Darwinism after reading an English copy of ''On the Origin of Species'' in the spring of 1860. Du Bois-Reymond was a committed supporter, securing Darwin an honorary degree from the University of Breslau, teaching his theory to students at the University of Berlin, and defending his name to paying audiences across Germany and The Netherlands. Du Bois-Reymond's exposition resembled Darwin's: he endorsed natural selection, rejected the inheritance of acquired characters, remained silent on the origin of variation, and identified "the altruism of bees, the regeneration of tissue, the effects of exercise, and the inheritance of disadvantageous traits" as puzzles presented by the theory.<ref>{{Cite book |last=Finkelstein |first=Gabriel |title=Emil du Bois-Reymond: Neuroscience, Self, and Society in Nineteenth-Century Germany |publisher=The MIT Press |year=2013 |isbn=978-0-262-01950-7 |location=Cambridge; London |pages=247 |language=English}}</ref>

Evolutionary ideas, although not natural selection, were accepted by other German biologists accustomed to ideas of [[Homology (biology)|homology]] in [[morphology (biology)|morphology]] from [[Johann Wolfgang von Goethe|Goethe]]'s ''[[Metamorphosis of Plants]]'' and from their long tradition of comparative anatomy. [[Heinrich Georg Bronn|Bronn]]'s alterations in his German translation added to the misgivings of conservatives but encouraged political radicals. [[Ernst Haeckel]] was particularly ardent, aiming to synthesise Darwin's ideas with those of [[Lamarckism|Lamarck]] and Goethe while still reflecting the spirit of ''[[Naturphilosophie]]''.<ref name="browne140" /><ref name="bowler186" /> His ambitious programme to reconstruct the [[evolutionary history of life]] was joined by Huxley and supported by discoveries in [[:paleontology|palaeontology]]. Haeckel used [[embryology]] extensively in his [[recapitulation theory]], which embodied a progressive, almost linear model of evolution. Darwin was cautious about such histories, and had already noted that [[Karl Ernst von Baer|von Baer's]] laws of embryology supported his idea of complex branching.<ref name="Bowler190_191">{{harvnb|Bowler|2003|pp=169–170, 190–192}}</ref>

[[Asa Gray]] promoted and defended ''Origin'' against those American naturalists with an idealist approach, notably [[Louis Agassiz]], who viewed every species as a distinct fixed unit in the mind of the Creator, classifying as species what others considered merely varieties.<ref>Dupree, pp. 216–232</ref> [[Edward Drinker Cope]] and [[Alpheus Hyatt]] reconciled this view with evolutionism in a form of [[Lamarckism#Neo-Lamarckism|neo-Lamarckism]] involving recapitulation theory.<ref name=bowler186>{{harvnb|Bowler|2003|pp=186–187, 237, 241}}</ref>

French-speaking naturalists in several countries showed appreciation of the much-modified French translation by [[Clémence Royer]], but Darwin's ideas had little impact in France, where any scientists supporting evolutionary ideas opted for a form of Lamarckism.<ref name=browne142/> The intelligentsia in Russia had accepted the general phenomenon of evolution for several years before Darwin had published his theory, and scientists were quick to take it into account, although the [[Malthusianism|Malthusian]] aspects were felt to be relatively unimportant. The political economy of struggle was criticised as a British stereotype by [[Karl Marx]] and by [[Leo Tolstoy]], who had the character Levin in his novel ''[[Anna Karenina]]'' voice sharp criticism of the morality of Darwin's views.<ref name=browne256/>

====Challenges to natural selection====
There were serious scientific objections to the process of [[natural selection]] as the key mechanism of evolution, including [[Carl Nägeli]]'s insistence that a trivial characteristic with no adaptive advantage could not be developed by selection. Darwin conceded that these could be linked to adaptive characteristics. His estimate that the [[age of the Earth]] allowed gradual evolution was disputed by [[William Thomson, 1st Baron Kelvin|William Thomson]] (later awarded the title Lord Kelvin), who calculated that the [[Sun]], and therefore life on Earth, was only about 100 million years old.<ref>{{harvnb|Kragh|2016|pp=11–12}}</ref> Darwin accepted [[blending inheritance]], but [[Fleeming Jenkin]] calculated that as it mixed traits, natural selection could not accumulate useful traits. Darwin tried to meet these objections in the fifth edition. [[St. George Jackson Mivart|Mivart]] supported directed evolution, and compiled scientific and religious objections to natural selection. In response, Darwin made considerable changes to the sixth edition. The problems of the age of the Earth and heredity were only resolved in the 20th century.<ref name=miv/><ref>{{harvnb|Bowler|2003|pp=198–200, 234–236}}</ref>

By the mid-1870s, most scientists accepted evolution, but relegated natural selection to a minor role as they believed evolution was purposeful and progressive. The range of evolutionary theories during "[[the eclipse of Darwinism]]" included forms of "[[Saltation (biology)|saltationism]]" in which new species were thought to arise through "jumps" rather than gradual adaptation, forms of [[orthogenesis]] claiming that species had an inherent tendency to change in a particular direction, and forms of neo-Lamarckism in which inheritance of acquired characteristics led to progress. The minority view of [[August Weismann]], that natural selection was the only mechanism, was called [[neo-Darwinism]]. It was thought that the rediscovery of [[Mendelian inheritance]] invalidated Darwin's views.<ref>{{harvnb|Bowler|2003|p=225}}</ref><ref name=Quammen205-234>{{Harvnb|Quammen|2006|pp=205–234}}</ref>