Evolution Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! == History of evolutionary thought == <!-- Note, this section is too long to be presented first, so it has been moved down. If it is shortened to three paragraphs or fewer it could be moved back up. See the lead of History of evolutionary thought for ideas on how to do that. --> {{main|History of evolutionary thought}} {{further|History of speciation}} [[File:Lucretius Rome.jpg|thumb|upright|[[Lucretius]]]] [[File:Alfred-Russel-Wallace-c1895.jpg|thumb|upright|[[Alfred Russel Wallace]]]] [[File:Thomas Robert Malthus Wellcome L0069037 -crop.jpg|thumb|upright|[[Thomas Robert Malthus]]]] [[File:Charles Darwin aged 51.jpg|thumb|upright|In 1842, [[Charles Darwin]] penned his first sketch of ''[[On the Origin of Species]]''.<ref>{{harvnb|Darwin|1909|p=53}}</ref>]] === Classical antiquity === The proposal that one type of organism could descend from another type goes back to some of the first [[pre-Socratic philosophy|pre-Socratic]] Greek philosophers, such as [[Anaximander#Origin of humankind|Anaximander]] and [[Empedocles#Cosmogony|Empedocles]].<ref>{{harvnb|Kirk|Raven|Schofield|1983|pp=100–142, 280–321}}</ref> Such proposals survived into Roman times. The poet and philosopher [[Lucretius]] followed Empedocles in his masterwork ''[[De rerum natura]]'' ({{lit|On the Nature of Things}}).<ref>{{harvnb|Lucretius}}</ref><ref>{{cite journal |last=Sedley |first=David |author-link=David Sedley |year=2003 |title=Lucretius and the New Empedocles |url=http://lics.leeds.ac.uk/2003/200304.pdf |journal=Leeds International Classical Studies |volume=2 |issue=4 |issn=1477-3643 |access-date=25 November 2014 |archive-url=https://web.archive.org/web/20140823062637/http://lics.leeds.ac.uk/2003/200304.pdf |archive-date=23 August 2014}}</ref> === Middle Ages === In contrast to these [[Materialism|materialistic]] views, [[Aristotelianism]] had considered all natural things as [[potentiality and actuality|actualisations]] of fixed natural possibilities, known as [[Theory of forms|forms]].<ref name="Torrey37">{{cite journal |last1=Torrey |first1=Harry Beal |last2=Felin |first2=Frances |date=March 1937 |title=Was Aristotle an Evolutionist? |url=https://archive.org/details/sim_quarterly-review-of-biology_1937-03_12_1/page/1 |journal=[[The Quarterly Review of Biology]] |volume=12 |issue=1 |pages=1–18 |doi=10.1086/394520 |issn=0033-5770 |jstor=2808399|s2cid=170831302 }}</ref><ref name="Hull67">{{cite journal |last=Hull |first=David L. |author-link=David Hull (philosopher) |date=December 1967 |title=The Metaphysics of Evolution |journal=[[The British Journal for the History of Science]] |location=[[Cambridge]] |publisher=[[Cambridge University Press]] on behalf of [[British Society for the History of Science|The British Society for the History of Science]] |volume=3 |issue=4 |pages=309–337 |doi=10.1017/S0007087400002892 |jstor=4024958|s2cid=170328394 }}</ref> This became part of a medieval [[teleology|teleological]] understanding of [[Nature (philosophy)|nature]] in which all things have an intended role to play in a [[divinity|divine]] [[cosmos|cosmic]] order. Variations of this idea became the standard understanding of the [[Middle Ages]] and were integrated into Christian learning, but Aristotle did not demand that real types of organisms always correspond one-for-one with exact metaphysical forms and specifically gave examples of how new types of living things could come to be.<ref>{{harvnb|Mason|1962|pp=43–44}}</ref> A number of Arab Muslim scholars wrote about evolution, most notably [[Ibn Khaldun]], who wrote the book ''[[Muqaddimah]]'' in 1377 AD, in which he asserted that humans developed from "the world of the monkeys", in a process by which "species become more numerous".<ref name=kiros>Kiros, Teodros. ''Explorations in African Political Thought''. 2001, page 55</ref> === Pre-Darwinian === The [[Scientific revolution|"New Science"]] of the 17th century rejected the Aristotelian approach. It sought to explain natural phenomena in terms of [[physical law]]s that were the same for all visible things and that did not require the existence of any fixed natural categories or divine cosmic order. However, this new approach was slow to take root in the biological sciences: the last bastion of the concept of fixed natural types. [[John Ray]] applied one of the previously more general terms for fixed natural types, "species", to plant and animal types, but he strictly identified each type of living thing as a species and proposed that each species could be defined by the features that perpetuated themselves generation after generation.<ref>{{harvnb|Mayr|1982|pp=256–257}} * {{harvnb|Ray|1686}}</ref> The [[biological classification]] introduced by [[Carl Linnaeus]] in 1735 explicitly recognised the hierarchical nature of species relationships, but still viewed species as fixed according to a divine plan.<ref>{{cite web |url=http://www.ucmp.berkeley.edu/history/linnaeus.html |title=Carl Linnaeus (1707–1778) |last=Waggoner |first=Ben |date=7 July 2000 |website=Evolution |publisher=[[University of California Museum of Paleontology]] |location=Berkeley, California |type=Online exhibit |access-date=11 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20110430160025/http://www.ucmp.berkeley.edu/history/linnaeus.html |archive-date=30 April 2011}}</ref> Other [[naturalists]] of this time speculated on the evolutionary change of species over time according to natural laws. In 1751, [[Pierre Louis Maupertuis]] wrote of natural modifications occurring during reproduction and accumulating over many generations to produce new species.<ref>{{harvnb|Bowler|2003|pp=73–75}}</ref> [[Georges-Louis Leclerc, Comte de Buffon]], suggested that species could degenerate into different organisms, and [[Erasmus Darwin]] proposed that all warm-blooded animals could have descended from a single microorganism (or "filament").<ref>{{cite web |url=http://www.ucmp.berkeley.edu/history/Edarwin.html |title=Erasmus Darwin (1731–1802) |date=4 October 1995 |website=Evolution |publisher=University of California Museum of Paleontology |location=Berkeley, California |type=Online exhibit |access-date=11 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120119004316/http://www.ucmp.berkeley.edu/history/Edarwin.html |archive-date=19 January 2012}}</ref> The first full-fledged evolutionary scheme was [[Jean-Baptiste Lamarck]]'s "transmutation" theory of 1809,<ref>{{harvnb|Lamarck|1809}}</ref> which envisaged [[spontaneous generation]] continually producing simple forms of life that developed greater complexity in parallel lineages with an inherent progressive tendency, and postulated that on a local level, these lineages adapted to the environment by inheriting changes caused by their use or disuse in parents.<ref name="Nardon_Grenier91">{{harvnb|Nardon|Grenier|1991|p=162}}</ref> (The latter process was later called [[Lamarckism]].)<ref name="Nardon_Grenier91" /><ref name="ImaginaryLamarck">{{cite journal |last=Ghiselin |first=Michael T. |author-link=Michael Ghiselin |date=September–October 1994 |title=The Imaginary Lamarck: A Look at Bogus 'History' in Schoolbooks |url=http://www.textbookleague.org/54marck.htm |journal=The Textbook Letter |oclc=23228649 |access-date=23 January 2008 |archive-url=https://web.archive.org/web/20080212174536/http://www.textbookleague.org/54marck.htm |archive-date=12 February 2008}}</ref><ref name="Jablonka07">{{cite journal |last1=Jablonka |first1=Eva |author-link1=Eva Jablonka |last2=Lamb |first2=Marion J. |s2cid=15879804 |author-link2=Marion J. Lamb |date=August 2007 |title=Précis of Evolution in Four Dimensions |journal=[[Behavioral and Brain Sciences]] |volume=30 |issue=4 |pages=353–365 |doi=10.1017/S0140525X07002221 |pmid=18081952 |issn=0140-525X}}</ref> These ideas were condemned by established naturalists as speculation lacking empirical support. In particular, [[Georges Cuvier]] insisted that species were unrelated and fixed, their similarities reflecting divine design for functional needs. In the meantime, Ray's ideas of benevolent design had been developed by [[William Paley]] into the ''[[Natural Theology or Evidences of the Existence and Attributes of the Deity]]'' (1802), which proposed complex adaptations as evidence of divine design and which was admired by Charles Darwin.<ref name="Darwin91">{{harvnb|Burkhardt|Smith|1991}} * {{cite news |url=http://www.darwinproject.ac.uk/letter/entry-2532 |title=Darwin, C. R. to Lubbock, John |website=[[Correspondence of Charles Darwin#Darwin Correspondence Project website|Darwin Correspondence Project]] |publisher=[[University of Cambridge]] |location=Cambridge |access-date=1 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20141215213940/http://www.darwinproject.ac.uk/letter/entry-2532 |archive-date=15 December 2014}} Letter 2532, 22 November 1859.</ref><ref name="Sulloway09">{{cite journal |last=Sulloway |first=Frank J. |s2cid=12289290 |author-link=Frank Sulloway |date=June 2009 |title=Why Darwin rejected intelligent design |journal=[[Journal of Biosciences]] |volume=34 |issue=2 |pages=173–183 |doi=10.1007/s12038-009-0020-8 |issn=0250-5991 |pmid=19550032}}</ref> === Darwinian revolution === The crucial break from the concept of constant typological classes or types in biology came with the theory of evolution through natural selection, which was formulated by [[Charles Darwin]] and [[Alfred Wallace]] in terms of variable populations. Darwin used the expression "'''descent with modification'''" rather than "evolution".<ref>{{Cite web |url=http://darwin-online.org.uk/content/search-results?pagesize=50&sort=date-ascending&pageno=0&freetext=descent+with+modification&allfields=&searchid=&name=Darwin+Charles+Robert&dateafter=&datebefore=&searchtitle=&description=&place=&publisher=&periodical= |title=Search results for "descent with modification" – The Complete Work of Charles Darwin Online |access-date=30 July 2022 |archive-date=5 June 2022 |archive-url=https://web.archive.org/web/20220605101314/http://darwin-online.org.uk/content/search-results?pagesize=50&sort=date-ascending&pageno=0&freetext=descent+with+modification&allfields=&searchid=&name=Darwin+Charles+Robert&dateafter=&datebefore=&searchtitle=&description=&place=&publisher=&periodical= |url-status=live }}</ref> Partly influenced by ''[[An Essay on the Principle of Population]]'' (1798) by [[Thomas Robert Malthus]], Darwin noted that population growth would lead to a "struggle for existence" in which favourable variations prevailed as others perished. In each generation, many offspring fail to survive to an age of reproduction because of limited resources. This could explain the diversity of plants and animals from a common ancestry through the working of natural laws in the same way for all types of organism.<ref name="Sober09">{{cite journal |last=Sober |first=Elliott |author-link=Elliott Sober |date=16 June 2009 |title=Did Darwin write the ''Origin'' backwards? |journal=[[Proceedings of the National Academy of Sciences of the United States of America|PNAS]] |volume=106 |issue=Suppl. 1 |pages=10048–10055 |bibcode=2009PNAS..10610048S |doi=10.1073/pnas.0901109106 |issn=0027-8424 |pmid=19528655 |pmc=2702806|doi-access=free }}</ref><ref>{{harvnb|Mayr|2002|p=165}}</ref><ref>{{harvnb|Bowler|2003|pp=145–146}}</ref><ref>{{cite journal |last1=Sokal |first1=Robert R. |author-link1=Robert R. Sokal |last2=Crovello |first2=Theodore J. |date=March–April 1970 |title=The Biological Species Concept: A Critical Evaluation |journal=[[The American Naturalist]] |volume=104 |issue=936 |pages=127–153 |doi=10.1086/282646 |issn=0003-0147 |jstor=2459191|s2cid=83528114 }}</ref> Darwin developed his theory of "natural selection" from 1838 onwards and was writing up his "big book" on the subject when [[Alfred Russel Wallace]] sent him a version of virtually the same theory in 1858. Their [[On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection|separate papers]] were presented together at an 1858 meeting of the [[Linnean Society of London]].<ref>{{cite journal |last1=Darwin |first1=Charles |author-link1=Charles Darwin |last2=Wallace |first2=Alfred |author-link2=Alfred Russel Wallace |date=20 August 1858 |title=On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection |url=http://darwin-online.org.uk/content/frameset?itemID=F350&viewtype=text&pageseq=1 |journal=[[Zoological Journal of the Linnean Society|Journal of the Proceedings of the Linnean Society of London. Zoology]] |volume=3 |issue=9 |pages=45–62 |doi=10.1111/j.1096-3642.1858.tb02500.x |issn=1096-3642 |access-date=13 May 2007 |url-status=live |archive-url=https://web.archive.org/web/20070714042318/http://darwin-online.org.uk/content/frameset?itemID=F350&viewtype=text&pageseq=1 |archive-date=14 July 2007|doi-access=free }}</ref> At the end of 1859, Darwin's publication of his "abstract" as ''On the Origin of Species'' explained natural selection in detail and in a way that led to an increasingly wide acceptance of [[Darwinism|Darwin's concepts of evolution]] at the expense of [[Alternatives to evolution by natural selection|alternative theories]]. [[Thomas Henry Huxley]] applied Darwin's ideas to humans, using [[paleontology]] and [[comparative anatomy]] to provide strong evidence that humans and [[ape]]s shared a common ancestry. Some were disturbed by this since it implied that humans did not have a special place in the [[universe]].<ref>{{cite encyclopedia |last=Desmond |first=Adrian J. |author-link=Adrian Desmond |encyclopedia=[[Encyclopædia Britannica Online]] |url=https://www.britannica.com/EBchecked/topic/277746/Thomas-Henry-Huxley |title=Thomas Henry Huxley |access-date=2 December 2014 |date=17 July 2014 |publisher=[[Encyclopædia Britannica, Inc.]] |location=Chicago, Illinois |url-status=live |archive-url=https://web.archive.org/web/20150119231241/https://www.britannica.com/EBchecked/topic/277746/Thomas-Henry-Huxley |archive-date=19 January 2015}}</ref> === Pangenesis and heredity === The mechanisms of reproductive heritability and the origin of new traits remained a mystery. Towards this end, Darwin developed his provisional theory of [[pangenesis]].<ref name="Liu09">{{cite journal |author1=Y. -S. Liu |author2=X. M. Zhou |author3=M. X. Zhi |author4=X. J. Li |author5=Q. L. Wang |s2cid=19919317 |date=September 2009 |title=Darwin's contributions to genetics |journal=Journal of Applied Genetics |volume=50 |issue=3 |pages=177–184 |doi=10.1007/BF03195671 |issn=1234-1983 |pmid=19638672}}</ref> In 1865, [[Gregor Mendel]] reported that traits were inherited in a predictable manner through the [[Mendelian inheritance#Law of Independent Assortment|independent assortment]] and segregation of elements (later known as genes). Mendel's laws of inheritance eventually supplanted most of Darwin's pangenesis theory.<ref name="Weiling">{{cite journal |last=Weiling |first=Franz |date=July 1991 |title=Historical study: Johann Gregor Mendel 1822–1884 |journal=[[American Journal of Medical Genetics]] |volume=40 |issue=1 |pages=1–25; discussion 26 |doi=10.1002/ajmg.1320400103 |pmid=1887835}}</ref> [[August Weismann]] made the important distinction between [[germ cell]]s that give rise to [[gamete]]s (such as [[sperm]] and [[egg cell]]s) and the [[somatic cell]]s of the body, demonstrating that heredity passes through the germ line only. [[Hugo de Vries]] connected Darwin's pangenesis theory to Weismann's germ/soma cell distinction and proposed that Darwin's pangenes were concentrated in the [[cell nucleus]] and when expressed they could move into the [[cytoplasm]] to change the [[Cell (biology)|cell]]'s structure. De Vries was also one of the researchers who made Mendel's work well known, believing that Mendelian traits corresponded to the transfer of heritable variations along the germline.<ref name="Wright84">{{harvnb|Wright|1984|p=480}}</ref> To explain how new variants originate, de Vries developed [[Mutationism|a mutation theory]] that led to a temporary rift between those who accepted Darwinian evolution and biometricians who allied with de Vries.<ref>{{harvnb|Provine|1971}}</ref><ref>{{cite journal |last1=Stamhuis |first1=Ida H. |last2=Meijer |first2=Onno G. |last3=Zevenhuizen |first3=Erik J. A. |date=June 1999 |title=Hugo de Vries on Heredity, 1889–1903: Statistics, Mendelian Laws, Pangenes, Mutations |url=https://archive.org/details/sim_isis_1999-06_90_2/page/238 |volume=90 |issue=2 |pages=238–267 |journal=[[Isis (journal)|Isis]] |doi=10.1086/384323 |jstor=237050 |pmid=10439561|s2cid=20200394 }}</ref> In the 1930s, pioneers in the field of [[population genetics]], such as [[Ronald Fisher]], [[Sewall Wright]] and [[J. B. S. Haldane]] set the foundations of evolution onto a robust statistical philosophy. The false contradiction between Darwin's theory, genetic mutations, and [[Mendelian inheritance]] was thus reconciled.{{sfn|Bowler|1989|pp=307–318}} === The 'modern synthesis' === {{main|Modern synthesis (20th century)}} In the 1920s and 1930s, the [[modern synthesis]] connected natural selection and population genetics, based on Mendelian inheritance, into a unified theory that included random genetic drift, mutation, and gene flow. This new version of evolutionary theory focused on changes in allele frequencies in population. It explained patterns observed across species in populations, through [[Transitional fossil|fossil transitions]] in palaeontology.{{sfn|Bowler|1989|pp=307–318}} === Further syntheses === Since then, further syntheses have extended evolution's explanatory power in the light of numerous discoveries, to cover biological phenomena across the whole of the [[Biological organisation|biological hierarchy]] from genes to populations.{{sfn|Levinson|2019}} The publication of the structure of [[DNA]] by [[James Watson]] and [[Francis Crick]] with contribution of [[Rosalind Franklin]] in 1953 demonstrated a physical mechanism for inheritance.<ref name="Watson53">{{cite journal |last1=Watson |first1=J. D. |author-link1=James Watson |last2=Crick |first2=F. H. C. |author-link2=Francis Crick |date=25 April 1953 |title=Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid |url=http://profiles.nlm.nih.gov/SC/B/B/Y/W/_/scbbyw.pdf |journal=[[Nature (journal)|Nature]] |volume=171 |issue=4356 |pages=737–738 |bibcode=1953Natur.171..737W |doi=10.1038/171737a0 |issn=0028-0836 |pmid=13054692 |s2cid=4253007 |access-date=4 December 2014 |quote=It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. |url-status=live |archive-url=https://web.archive.org/web/20140823063212/http://profiles.nlm.nih.gov/SC/B/B/Y/W/_/scbbyw.pdf |archive-date=23 August 2014}}</ref> [[Molecular biology]] improved understanding of the relationship between [[genotype]] and [[phenotype]]. Advances were also made in phylogenetic [[systematics]], mapping the transition of traits into a comparative and testable framework through the publication and use of [[Phylogenetic tree|evolutionary trees]].<ref name="Hennig99">{{harvnb|Hennig|1999|p=280}}</ref> In 1973, evolutionary biologist [[Theodosius Dobzhansky]] penned that "[[Nothing in Biology Makes Sense Except in the Light of Evolution|nothing in biology makes sense except in the light of evolution]]", because it has brought to light the relations of what first seemed disjointed facts in natural history into a coherent [[Explanation|explanatory]] body of knowledge that describes and predicts many observable facts about life on this planet.<ref name="Dobzhansky73">{{cite journal |last=Dobzhansky |first=Theodosius |s2cid=207358177 |author-link=Theodosius Dobzhansky |date=March 1973 |title=Nothing in Biology Makes Sense Except in the Light of Evolution |url=http://www.phil.vt.edu/Burian/NothingInBiolChFina.pdf |journal=The American Biology Teacher |volume=35 |issue=3 |pages=125–129 |doi=10.2307/4444260 |url-status=dead |archive-url=https://web.archive.org/web/20151023161423/http://www.phil.vt.edu/Burian/NothingInBiolChFina.pdf |archive-date=23 October 2015 |jstor=4444260 |citeseerx=10.1.1.324.2891}}</ref> One extension, known as [[evolutionary developmental biology]] and informally called "evo-devo", emphasises how changes between generations (evolution) act on patterns of change within individual organisms ([[Developmental biology|development]]).<ref name="Kutschera">{{cite journal |last1=Kutschera |first1=Ulrich |author-link1=Ulrich Kutschera |last2=Niklas |first2=Karl J. |author-link2=Karl J. Niklas |date=June 2004 |title=The modern theory of biological evolution: an expanded synthesis |journal=[[Naturwissenschaften]] |volume=91 |issue=6 |pages=255–276 |bibcode=2004NW.....91..255K |doi=10.1007/s00114-004-0515-y |issn=1432-1904 |pmid=15241603|s2cid=10731711 }}</ref><ref name="Avise10">{{cite journal |last1=Avise |first1=John C. |author-link1=John Avise |last2=Ayala |first2=Francisco J. |author-link2=Francisco J. Ayala |date=11 May 2010 |title=In the light of evolution IV: The human condition |url=http://faculty.sites.uci.edu/johncavise/files/2011/03/311-intro-to-ILE-IV.pdf |journal=PNAS |volume=107 |issue=Suppl. 2 |pages=8897–8901 |doi=10.1073/pnas.1003214107 |pmid=20460311 |pmc=3024015 |issn=0027-8424 |access-date=29 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20140823063532/http://faculty.sites.uci.edu/johncavise/files/2011/03/311-intro-to-ILE-IV.pdf |archive-date=23 August 2014|doi-access=free }}</ref> Since the beginning of the 21st century, some biologists have argued for an [[extended evolutionary synthesis]], which would account for the effects of non-genetic inheritance modes, such as [[epigenetics]], [[Maternal effect|parental effects]], ecological inheritance and [[Dual inheritance theory|cultural inheritance]], and [[evolvability]].<ref name="beyonddna">{{cite journal |last1=Danchin |first1=Étienne |last2=Charmantier |first2=Anne |last3=Champagne |first3=Frances A. |author-link3=Frances Champagne |last4=Mesoudi |first4=Alex |last5=Pujol |first5=Benoit |last6=Blanchet |first6=Simon |date=June 2011 |title=Beyond DNA: integrating inclusive inheritance into an extended theory of evolution |journal=[[Nature Reviews Genetics]] |volume=12 |issue=7 |pages=475–486 |doi=10.1038/nrg3028 |issn=1471-0056 |pmid=21681209|s2cid=8837202 }}</ref><ref name="eesbook">{{harvnb|Pigliucci|Müller|2010}}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. 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