Editing Homology (biology) (section)

==History==
[[File:BelonBirdSkel.jpg|thumb|upright=1.35|[[Pierre Belon]] systematically compared the skeletons of birds and humans in his ''Book of Birds'' (1555).<ref name="Panchen 1999"/>]]

Homology was noticed by [[Aristotle's biology|Aristotle]] (c. 350 BC),<ref name="Panchen 1999">{{cite book | last=Panchen | first=A. L. | title= Novartis Foundation Symposium 222 - Homology| chapter=Homology — History of a Concept | series=Novartis Foundation Symposia | volume=222 | year=1999 | pmid=10332750 | pages=5–18; discussion 18–23| doi=10.1002/9780470515655.ch2 | isbn=9780470515655 }}</ref> and was explicitly analysed by [[Pierre Belon]] in his 1555 ''Book of Birds'', where he systematically compared the skeletons of birds and humans. The pattern of similarity was interpreted as part of the static [[great chain of being]] through the [[mediaeval]] and [[early modern]] periods: it was not then seen as implying evolutionary change. In the German ''[[Naturphilosophie]]'' tradition, homology was of special interest as demonstrating unity in nature.<ref name=Panchen1999>{{cite book |last=Panchen |first=A. L. |title=Novartis Foundation Symposium 222 - Homology |chapter=Homology — History of a Concept |journal=Novartis Foundation Symposium |series=Novartis Foundation Symposia |date=1999 |volume=222 |pages=5–18 |doi=10.1002/9780470515655.ch2 |pmid=10332750|isbn=9780470515655 }}</ref><ref name=Brigandt/> In 1790, [[Goethe]] stated his [[foliar theory]] in his essay "Metamorphosis of Plants", showing that flower parts are derived from leaves.<ref name=Dornelas>{{cite journal |doi=10.1590/S1677-04202005000400001 |title=From leaf to flower: Revisiting Goethe's concepts on the ¨metamorphosis¨ of plants |year=2005 |last1=Dornelas |first1=Marcelo Carnier |last2=Dornelas |first2=Odair |journal=Brazilian Journal of Plant Physiology |volume=17 |issue=4|pages=335–344 |doi-access=free }}</ref> The [[serial homology]] of limbs was described late in the 18th century. The French zoologist [[Étienne Geoffroy Saint-Hilaire]] showed in 1818 in his ''theorie d'analogue'' ("theory of homologues") that structures were shared between fishes, reptiles, birds and mammals.<ref>{{cite book |last=Geoffroy Saint-Hilaire |first=Étienne |author-link=Étienne Geoffroy Saint-Hilaire |url=https://www.biodiversitylibrary.org/item/18524#page/6/mode/1up |title=Philosophie anatomique. Vol. 1: Des organes respiratoires sous le rapport de la détermination et de l'identité de leurs piecès osseuses |date=1818 |publisher=J. B. Baillière |volume=1 |location=Paris}}</ref> When Geoffroy went further and sought homologies between [[Georges Cuvier]]'s ''[[embranchement]]s'', such as vertebrates and molluscs, his claims triggered the 1830 [[Cuvier–Geoffroy debate]]. Geoffroy stated the principle of connections, namely that what is important is the relative position of different structures and their connections to each other.<ref name="Brigandt">{{cite web |last=Brigandt |first=Ingo |title=Essay: Homology |url=https://embryo.asu.edu/pages/essay-homology |website=The Embryo Project Encyclopedia |date=23 November 2011}}</ref> [[Embryologist]] [[Karl Ernst von Baer]] stated what are now called [[von Baer's laws]] in 1828, noting that related animals begin their development as similar embryos and then diverge: thus, animals in the same [[family (biology)|family]] are more closely related and diverge later than animals which are only in the same [[order (biology)|order]] and have fewer homologies. Von Baer's theory recognises that each [[taxon]] (such as a family) has distinctive shared features, and that embryonic development parallels the taxonomic hierarchy: not the same as [[recapitulation theory]].<ref name="Brigandt"/> The term "homology" was first used in biology by the anatomist [[Richard Owen]] in 1843 when studying the similarities of vertebrate [[fin]]s and limbs, defining it as the "same organ in different animals under every variety of form and function",<ref>{{cite book |last=Owen |first=Richard |author-link=Richard Owen |url=https://www.biodiversitylibrary.org/item/29826#page/5/mode/1up |title=Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals, Delivered at the Royal College of Surgeons in 1843 |date=1843 |publisher=Longman, Brown, Green, and Longmans |pages=374, 379}}</ref> and contrasting it with the matching term "analogy" which he used to describe different structures with the same function. Owen codified three main criteria for determining if features were homologous: position, development and composition. In 1859, [[Charles Darwin]] explained homologous structures as meaning that the organisms concerned shared a [[body plan]] from a common ancestor, and that taxa were branches of a single [[tree of life (biology)|tree of life]].<ref name=Panchen1999/><ref name="Brigandt"/><ref>{{cite journal |last=Sommer |first=R. J. |date=July 2008 |title=Homology and the hierarchy of biological systems |journal=BioEssays |volume=30 |issue=7 |pages=653–658 |doi=10.1002/bies.20776 |pmid=18536034}}</ref>