Editing Modern synthesis (20th century) (section)

===Schmalhausen's stabilizing selection, 1941===
{{further|Stabilizing selection}}

[[Ivan Schmalhausen]] developed the theory of [[stabilizing selection]], the idea that selection can preserve a trait at some value, publishing a paper in Russian titled "Stabilizing selection and its place among factors of evolution" in 1941 and a monograph ''Factors of Evolution: The Theory of Stabilizing Selection''<ref>{{cite book |last1=Schmalhausen |first1=Ivan I. |last2=Dordick |first2=Isadore (trans.)|author-link1=Ivan Schmalhausen |editor1-last=Dobzhansky|editor1-first=Theodosius |editor1-link=Theodosius Dobzhansky |title=Factors of Evolution. The Theory of Stabilizing Selection |date=1949 |publisher=[[Blakiston Company]] |location=Philadelphia and Toronto}}</ref> in 1945. He developed it from J. M. Baldwin's 1902 concept that changes induced by the environment will ultimately be replaced by hereditary changes (including the [[Baldwin effect]] on behaviour), following that theory's implications to their Darwinian conclusion, and bringing him into conflict with Lysenkoism. Schmalhausen observed that stabilizing selection would remove most variations from the norm, most mutations being harmful.<ref name=Levit2006>{{cite journal | last=Levit | first=Georgy S. |author2=Hossfeld, Uwe |author3=Olsson, Lennart | title=From the 'Modern Synthesis' to Cybernetics: Ivan Ivanovich Schmalhausen (1884–1963) and his Research Program for a Synthesis of Evolutionary and Developmental Biology | journal=[[Journal of Experimental Zoology]] | volume=306B | issue=2006 | pages=89–106 | year=2006 | pmid=16419076 | doi=10.1002/jez.b.21087| s2cid=23594114 }}</ref><ref name=Adams1988>{{cite journal |author=Adams, M. B. |title=A Missing Link in the Evolutionary Synthesis. I. I. Schmalhausen. Factors of Evolution: The Theory of Stabilizing Selection |journal=Isis |date=June 1988 |volume=79 |issue=297 |pages=281–284 |doi=10.1086/354706 |pmid=3049441|s2cid=146660877 }}</ref><ref>{{cite journal |last1=Glass |first1=Bentley |title=Reviews and Brief Notices Factors of Evolution. The Theory of Stabilizing Selection. I. I. Schmalhausen, Isadore Dordick, Theodosius Dobzhansky |journal=[[Quarterly Review of Biology]] |date=December 1951 |volume=26 |issue=4 |pages=384–385 |doi=10.1086/398434}}</ref> Dobzhansky called the work "an important missing link in the modern view of evolution".{{sfn|Mayr|Provine|1998|p=ix}}