Editing Evolutionary developmental biology (section)

===The modern synthesis of the early 20th century===
{{Main|Modern synthesis (20th century)}}

In the so-called [[Modern synthesis (20th century)|modern synthesis]] of the early 20th century, between 1918 and 1930 [[Ronald Fisher]] brought together Darwin's theory of [[evolution]], with its insistence on natural selection, [[heredity]], and [[genotype|variation]], and [[Gregor Mendel]]'s [[Mendelian inheritance|laws of genetics]] into a coherent structure for [[evolutionary biology]]. Biologists assumed that an organism was a straightforward reflection of its component genes: the genes coded for proteins, which built the organism's body. Biochemical pathways (and, they supposed, new species) evolved through [[mutation]]s in these genes. It was a simple, clear and nearly comprehensive picture: but it did not explain embryology.<ref name=Gilbert2003/><ref>{{Cite journal |last=Bock |first=Walter J. |date=July 1981 |title=Reviewed Work: ''The Evolutionary Synthesis. Perspectives on the Unification of Biology'' |journal=[[The Auk]] |volume=98 |issue=3 |pages=644–646 |jstor=4086148}}</ref> [[Sean B. Carroll]] has commented that had evo-devo's insights been available, embryology would certainly have played a central role in the synthesis.<ref name=Carroll_2008/>

The evolutionary embryologist [[Gavin de Beer]] anticipated evolutionary developmental biology in his 1930 book ''[[Embryos and Ancestors]]'',<ref name="Held">{{Cite book |last=Held |first=Lewis I. |author-link=Lewis I. Held |title=How the Snake Lost its Legs. Curious Tales from the Frontier of Evo-Devo |title-link=How the Snake Lost its Legs |date=2014 |publisher=[[Cambridge University Press]] |isbn=978-1-107-62139-8 |page=67}}</ref> by showing that evolution could occur by [[heterochrony]],<ref>{{harvnb|Gould|1977|pp=221–222}}</ref> such as in [[paedomorphosis|the retention of juvenile features in the adult]].<ref name="ReferenceA" /> This, de Beer argued, could cause apparently sudden changes in the [[fossil record]], since embryos fossilise poorly. As the gaps in the fossil record had been used as an argument against Darwin's gradualist evolution, de Beer's explanation supported the Darwinian position.<ref>{{Cite journal |last=Brigandt |first=Ingo |year=2006 |title=Homology and heterochrony: the evolutionary embryologist Gavin Rylands de Beer (1899-1972) |url=https://www.ualberta.ca/~brigandt/de_Beer.pdf |journal=[[Journal of Experimental Zoology]] |volume=306B |issue=4 |pages=317–328 |bibcode=2006JEZB..306..317B |doi=10.1002/jez.b.21100 |pmid=16506229}}</ref> However, despite de Beer, the modern synthesis largely ignored embryonic development to explain the form of organisms, since population genetics appeared to be an adequate explanation of how forms evolved.<ref name="Gilbert1991">{{Cite journal |last=Gilbert |first=S. F. |last2=Opitz |first2=J. M. |last3=Raff |first3=R. A. |date=1996 |title=Resynthesizing evolutionary and developmental biology |journal=Developmental Biology |volume=173 |issue=2 |pages=357–372 |doi=10.1006/dbio.1996.0032 |pmid=8605997 |doi-access=free}}</ref><ref>{{Cite book |last=Adams, M. |title=New Perspectives in Evolution |date=1991 |publisher=Liss/Wiley |editor-last=Warren, L. |pages=37–63 |chapter=Through the looking glass: The evolution of Soviet Darwinism |editor-last2=Koprowski, H.}}</ref>{{efn|Though [[C. H. Waddington]] had called for embryology to be added to the synthesis in his 1953 paper "Epigenetics and Evolution".<ref name="Smocovitis153">{{harvnb|Smocovitis|1996|page=153}}</ref>}}