Sewall Wright

Sewall Wright was born in Melrose, Massachusetts, to Philip Green Wright and Elizabeth Quincy Sewall Wright. His parents were first cousins,{{cite book|last1=Allendorf|first1=Fred W.|last2=Luikart|first2=Gordon H.|last3=Aitken|first3=Sally N.|title=Conservation and the Genetics of Populations|url=https://books.google.com/books?id=VVploytG8jYC&pg=PT548|year=2012|publisher=John Wiley|isbn=978-1-118-40857-5|page=548}}. So were Darwin and his wife Emma (Wedgwood). an interesting fact in light of Wright's later research on inbreeding. The family moved three years later after Philip accepted a teaching job at Lombard College, a Universalist college in Galesburg, Illinois.

As a child, Wright helped his father and brother print and publish an early book of poems by his father's student Carl Sandburg. At the age of seven, in 1897, he wrote his first "book", entitled Wonders of Nature, and he published his last paper in 1988:{{cite journal | last= Wright | first= S. | date = 1988 | title = Surfaces of selective value revisited | journal= Am. Nat. | volume = 131 | issue= 1 | pages= 115–123| doi= 10.1086/284777 | bibcode= 1988ANat..131..115W | s2cid= 85397524 }} he can be claimed, therefore, to be the scientist with the longest career of science writing. Wright's astonishing maturity at the age of seven may be judged from the following excerpt quoted in the obituary:

Have you ever examined the gizzard of a fowl? The gizzard of a fowl is a deep red colar with blu at the top. First on the outside is a very thick muscle. Under this is a white and fleecy layer. Holding very tight to the other. I expect you know that chickens eat sand. The next two layers are rough and rumply. These layers hold the sand. They grind the food. One night when we had company we had chicken-pie. Our Aunt Polly cut open the gizzard, and in it we found a lot of grain, and some corn.

He was the oldest of three gifted brothers—the others being the aeronautical engineer Theodore Paul Wright and the political scientist Quincy Wright. From an early age Wright had a love and talent for mathematics and biology. Wright attended Galesburg High School and graduated in 1906. He then enrolled in Lombard College where his father taught, to study mathematics. He was influenced greatly by Professor Wilhelmine Key, one of the first women to receive a Ph.D. in biology.{{Cite journal |last=Wright |first=Sewall |title=Dr. Wilhelmine Key |date=September 1, 1965 |url=https://academic.oup.com/jhered/article/870066/DR. |journal=Journal of Heredity |language=en |volume=56 |issue=5 |pages=195–196 |doi=10.1093/oxfordjournals.jhered.a107413 |pmid=5323812 |issn=1465-7333|url-access=subscription }}{{Cite journal |last=Crow |first=J. F. |date=2004-09-01 |title=The Wilhemine E. Key 2003 Invitational Lecture: Genetics: Alive and Well. The First Hundred Years as Viewed Through the Pages of the Journal of Heredity |journal=Journal of Heredity |language=en |volume=95 |issue=5 |pages=365–374 |doi=10.1093/jhered/esh061 |pmid=15388764 |issn=0022-1503|doi-access=free }}{{Cite web |last=Lescouflair |first=Edric |title=The Life of Sewall Wright |url=https://www.harvardsquarelibrary.org/biographies/sewall-wright/ |access-date=September 20, 2022 |website=Harvard Square Library}} Wright received his Ph.D. from Harvard University, where he worked at the Bussey Institute with the pioneering mammalian geneticist William Ernest Castle investigating the inheritance of coat colors in mammals. He worked for the U.S. Department of Agriculture until 1925, when he joined the Department of Zoology at the University of Chicago. He remained there until his retirement in 1955, when he moved to the University of Wisconsin–Madison. He received many honors in his long career, including the National Medal of Science (1966), the Balzan Prize (1984), and the Darwin Medal of the Royal Society (1980). He was a member of the National Academy of Sciences,{{Cite web |title=Sewall Wright |url=http://www.nasonline.org/member-directory/deceased-members/48919.html |access-date=2023-06-26 |website=www.nasonline.org}} the American Philosophical Society,{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Sewall+Wright&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-06-26 |website=search.amphilsoc.org}} the American Academy of Arts and Sciences,{{Cite web |date=2023-02-09 |title=Sewall Wright |url=https://www.amacad.org/person/sewall-wright |access-date=2023-06-26 |website=American Academy of Arts & Sciences |language=en}} and a Foreign Member of the Royal Society. The American Mathematical Society selected him as the Josiah Willards Gibbs lecturer for 1941.{{cite web|url=http://www.ams.org/meetings/lectures/meet-gibbs-lect|title=American Mathematical Society|website=www.ams.org|access-date=March 21, 2018}}{{cite journal|author=Wright, Sewall|title=Statistical genetics and evolution|journal=Bull. Amer. Math. Soc.|year=1942|volume=48|issue=4|pages=223–246|mr=0006700|doi=10.1090/S0002-9904-1942-07641-5|doi-access=free}} For his work on genetics of evolutionary processes, Wright was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences in 1945.{{cite web|title=Daniel Giraud Elliot Medal|url=http://www.nasonline.org/programs/awards/daniel-giraud-elliot-medal.html|access-date=January 7, 2018}}

He died in Madison, Wisconsin, on March 3, 1988.

Wright married Louise Lane Williams (1895–1975) in 1921."Ohio Marriages, 1800-1958," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:XD4D-1CD : December 8, 2014), Sewall Wright and Louise Lane Williams, September 10, 1921; citing Licking, Ohio, reference 508B; FHL microfilm 384,312.{{cite book|last1=Provine|first1=William B.|title=Wright and Evolutionary Biology|date=1989|publisher=University of Chicago Press|isbn=9780226684734|page=[https://archive.org/details/sewallwrightevol00will/page/106 106]|url=https://archive.org/details/sewallwrightevol00will|url-access=registration|access-date=January 7, 2018|quote="They were married in Granville on September 10, 1921... The Wrights had two boys, Richard and Robert, during the remaining four years in Washington."}} They had three children: Richard, Robert, and Elizabeth."United States Census, 1930," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:XSTH-NZW : accessed January 7, 2018), Sewall Wright, Chicago (Districts 0001-0250), Cook, Illinois, United States; citing enumeration district (ED) ED 208, sheet 11A, line 50, family 226, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 423; FHL microfilm 2,340,158.{{cite web|url=http://www.nndb.com/people/234/000103922/|title=Sewall Wright Profile}}

Sewall Wright worshipped as a Unitarian.{{cite book|last1=Ruse|first1=Michael|title=Monad to Man: The Concept of Progress in Evolutionary Biology|date=June 30, 2009|publisher=Harvard University Press|isbn=9780674042995|page=376|url=https://books.google.com/books?id=o0jN9RdWz1MC&q=%22Wright+worshipped+as+a+Unitarian%22&pg=PA376|access-date=January 7, 2018|archive-url=https://archive.today/20180107083524/https://books.google.hu/books?id=o0jN9RdWz1MC&pg=PA376&lpg=PA376&dq=Sewall+Wright+was+a+Unitarian&source=bl&ots=N_Tv5vtl3O&sig=4nMO-WM-tLJZTCdLcdAr-pFWu6k&hl=en&sa=X&redir_esc=y%23v=onepage&q=Sewall%20Wright%20was%20a%20Unitarian&f=false|archive-date=January 7, 2018|quote="Wright worshipped as a Unitarian"}}{{cite book|last1=Provine|first1=William B.|title=Sewall Wright and Evolutionary Biology|date=1989|publisher=University of Chicago Press|isbn=9780226684734|pages=[https://archive.org/details/sewallwrightevol00will/page/460 460], 497|url=https://archive.org/details/sewallwrightevol00will|url-access=registration|quote=Unitarian.|access-date=January 7, 2018}}

File:Visualization of two dimensions of a NK fitness landscape.png

His papers on inbreeding,{{cite journal | doi= 10.1086/280891| title= Breeding Structure of Populations in Relation to Speciation| year= 1940| last1= Wright| first1= Sewall| journal= The American Naturalist| volume= 74| issue= 752| pages= 232–248| bibcode= 1940ANat...74..232W| s2cid= 84048953}} mating systems,{{cite journal | title=Isolation by distance under diverse systems of mating | last=Wright | first =S | journal =Genetics | volume=31 | issue=1 | pages=39–59 | date=1946| doi=10.1093/genetics/31.1.39 | pmid=21009706 | pmc=1209315 }} and genetic drift{{cite journal | doi= 10.1111/j.1558-5646.1948.tb02746.x| title= On the Roles of Directed and Random Changes in Gene Frequency in the Genetics of Populations| year= 1948| last1= Wright| first1= Sewall| journal= Evolution| volume= 2| issue= 4| pages= 279–294| pmid= 18104586| doi-access= free}} make him a principal founder of theoretical population genetics, along with R. A. Fisher and J. B. S. Haldane. Their theoretical work is the origin of the modern evolutionary synthesis or neo-Darwinian synthesis.{{cite journal | doi= 10.1093/oxfordjournals.jhered.a103361| title= The Genetical Theory of Natural Selection| year= 1930| last1= Wright| first1= Sewall| journal= Journal of Heredity| volume= 21| issue= 8| pages= 349–356}} Wright was the inventor/discoverer of the inbreeding coefficient and F-statistics, standard tools in population genetics. He was the chief developer of the mathematical theory of genetic drift, which is sometimes known as the Sewall Wright effect,The Structure of Evolutionary Theory (2002) by Stephen Jay Gould, Chapter 7, section "Synthesis as Hardening" cumulative stochastic changes in gene frequencies that arise from random births, deaths, and Mendelian segregations in reproduction. In this work he also introduced the concept of effective population size. Wright was convinced that the interaction of genetic drift and the other evolutionary forces was important in the process of adaptation. He described the relationship between genotype or phenotype and fitness as fitness surfaces or evolutionary landscapes. On these landscapes mean population fitness was the height, plotted against horizontal axes representing the allele frequencies or the average phenotypes of the population. Natural selection would lead to a population climbing the nearest peak, while genetic drift would cause random wandering. He did not accept Fisher's genetic theory of dominance,{{cite journal | doi= 10.1086/280289| title= The Evolution of Dominance; Reply to Professor Sewall Wright| year= 1929| last1= Fisher| first1= R. A.| journal= The American Naturalist| volume= 63| issue= 689| pages= 553–556| bibcode= 1929ANat...63..553F| hdl= 2440/15105| s2cid= 84667207| hdl-access= free}} but instead considered it to arise from biochemical considerations.{{cite journal | doi= 10.1086/280290| title= The Evolution of Dominance| year= 1929| last1= Wright| first1= Sewall| journal= The American Naturalist| volume= 63| issue= 689| pages= 556–561| bibcode= 1929ANat...63..556W| s2cid= 85301374}}{{cite journal | doi= 10.1086/280521| title= Physiological and Evolutionary Theories of Dominance| year= 1934| last1= Wright| first1= Sewall| journal= The American Naturalist| volume= 68| issue= 714| pages= 24–53| bibcode= 1934ANat...68...24W| s2cid= 84400871}} Although set aside for many years, his interpretation is at the basis of modern ideas of dominance.{{cite journal | title = The molecular-basis of dominance | last1= Kacser | first1= H | last2 = Burns | first2 = J.A. | journal = Genetics | volume = 97 | issue= 3–4 | pages= 639–666 | date = 1981| doi= 10.1093/genetics/97.3-4.639 | pmid= 7297851 | pmc= 1214416 }}{{cite journal | doi= 10.1073/pnas.88.24.11413| title= A test of Fisher's theory of dominance| year= 1991| last1= Orr| first1= H. A.| journal= Proceedings of the National Academy of Sciences| volume= 88| issue= 24| pages= 11413–11415| pmid= 1763055| pmc= 53145| bibcode= 1991PNAS...8811413O| doi-access= free}}

Wright's explanation for stasis was that organisms come to occupy adaptive peaks.{{cite journal | doi= 10.1073/pnas.23.6.307| title= The Distribution of Gene Frequencies in Populations| year= 1937| last1= Wright| first1= S.| journal= Proceedings of the National Academy of Sciences| volume= 23| issue= 6| pages= 307–320| pmid= 16577780| pmc= 1076930| bibcode= 1937PNAS...23..307W| doi-access= free}} In order to evolve to another, higher peak, the species would first have to pass through a valley of maladaptive intermediate stages. This could happen by genetic drift if the population is small enough. If a species was divided into small populations, some could find higher peaks. If there was some gene flow between the populations, these adaptations could spread to the rest of the species. This was Wright's shifting balance theory of evolution. There has been much skepticism among evolutionary biologists as to whether these rather delicate conditions hold often in natural populations. Wright had a long-standing and bitter debate about this with R. A. Fisher, who felt that most populations in nature were too large for these effects of genetic drift to be important.

Wright's statistical method of path analysis,{{cite journal | doi= 10.2307/2527693| jstor= 2527693| title= The Treatment of Reciprocal Interaction, with or without Lag, in Path Analysis| last1= Wright| first1= Sewall| journal= Biometrics| year= 1960| volume= 16| issue= 3| pages= 423–445}} which he invented in 1921 and which was one of the first methods using a graphical model, is still widely used in social science. He was a hugely influential reviewer of manuscripts, as one of the most frequent reviewers for Genetics.

Wright strongly influenced Jay Lush, who was the most influential figure in introducing quantitative genetics into animal and plant breeding. From 1915 to 1925 Wright was employed by the Animal Husbandry Division of the U.S. Bureau of Animal Husbandry. His main project was to investigate the inbreeding that had occurred in the artificial selection that resulted in the leading breeds of livestock used in American beef production. He also performed experiments with 80,000 guinea pigs in the study of physiological genetics. Furthermore he analyzed characters of some 40,000 guinea pigs in 23 strains of brother-sister matings against a random-bred stock. (Wright 1922a-c). The concentrated study of these two groups of mammals eventually led to the Shifting Balance Theory and the concept of "surfaces of selective value" in 1932.

He did major work on the genetics of guinea pigs,{{cite journal | doi= 10.1086/280125| title= Effects of Age of Parents on Characteristics of the Guinea Pig| year= 1926| last1= Wright| first1= Sewall| journal= The American Naturalist| volume= 60| issue= 671| pages= 552–559| bibcode= 1926ANat...60..552W| s2cid= 84805740}}{{cite journal | doi= 10.1002/jcp.1030560413| title= The genetics of vital characters of the guinea pig| year= 1960| last= Wright| first= Sewall| journal= Journal of Cellular and Comparative Physiology| volume= 56| pages= 123–151| pmid= 13786823}} and many of his students became influential in the development of mammalian genetics. He appreciated as early as 1917 that genes acted by controlling enzymes. An anecdote about Wright, disclaimed by Wright himself, describes a lecture during which Wright tucked an unruly guinea pig under his armpit, where he usually held a chalkboard eraser: according to the anecdote, at the conclusion of the lecture, Wright absent-mindedly began to erase the blackboard using the guinea pig.{{citation needed|date=July 2018}}

The creation of the statistical coefficient of determination has been attributed to Sewall Wright and was first published in 1921.{{cite journal |last=Wright |first=Sewall|date=January 1921 |title=Correlation and causation |journal=Journal of Agricultural Research |volume=20 |pages=557–585}}

This metric is commonly employed to evaluate regression analyses in computational statistics and machine learning.

Wright was one of the few geneticists of his time to venture into philosophy. He found a union of concept in Charles Hartshorne, who became a lifelong friend and philosophical collaborator. Wright endorsed a form of panpsychism. He believed that the birth of the consciousness was not due to a mysterious property of increasing complexity, but rather an inherent property, therefore implying these properties were in the most elementary particles.{{cite journal | last1 = Steffes | first1 = David M | year = 2007 | title = Panpsychic Organicism: Sewall Wright's Philosophy for Understanding Complex Genetic Systems | journal = Journal of the History of Biology | volume = 40 | issue = 2| pages = 327–361 | doi = 10.1007/s10739-006-9105-5 | pmid = 18175605 | s2cid = 3255830 }}

Wright and Fisher, along with J.B.S. Haldane, were the key figures in the modern synthesis that brought genetics and evolution together. Their work was essential to the contributions of Dobzhansky, Mayr, Simpson, Julian Huxley, and Stebbins. The modern synthesis was the most important development in evolutionary biology after Darwin. Wright also had a major effect on the development of mammalian genetics and biochemical genetics.

Judea Pearl and Dana Mackenzie's The Book of Why (2018) describes the contribution of Wright's work on path analysis and delays in its acceptance by several technical disciplines (specifically statistics and formal causal analysis).{{cite book |last1=Pearl |first1=Judea |title=The Book of Why |date=May 2018 |publisher=Basic Books |location=New York |isbn=978-0-465-09760-9 |page=6 }}

OpenMx has as its icon a representation of Wright's piebald guinea pig.

• {{cite book | author=Wright, Sewall | year=1984| title= Evolution and the Genetics of Populations: Genetics and Biometric Foundations New Edition | publisher=University of Chicago Press}}
• vol. 1, Genetic & Biometric Foundations. {{ISBN|0-226-91038-5}}
• vol. 2, Theory of Gene Frequencies. {{ISBN|0-226-91039-3}}
• vol. 3, Experimental Results and Evolutionary Deductions. {{ISBN|0-226-91040-7}}
• vol. 4, Variability within and Among Natural Populations. {{ISBN|0-226-91041-5}}

{{Reflist}}

• Ghiselin, Michael T. (1997) [https://books.google.com/books?id=GS7zerl8_SoC Metaphysics and the Origin of Species]. NY: SUNY Press.
• {{cite book | author=Provine, William | year=1986 | title=Sewall Wright and Evolutionary Biology | publisher=University of Chicago Press | isbn=978-0-226-68473-4 | url-access=registration | url=https://archive.org/details/sewallwrightevol00will | author-link=Will Provine }}
• {{Cite journal | last1 = Wright | first1 = Sewall | year = 1932 | title = The roles of mutation, inbreeding, crossbreeding and selection in evolution | url = http://www.blackwellpublishing.com/ridley/classictexts/wright.asp | journal = Proc. 6th Int. Cong. Genet | volume = 1 | pages = 356–366 }}
• Wright 1934, [https://www.gwern.net/docs/statistics/1934-wright.pdf "The Method of Path Coefficients"], Annals of Mathematical Statistics, 5: 161-215
• {{cite book | author=Wright, Sewall | year=1986 |title=Evolution: Selected papers | publisher=University of Chicago Press |url= https://archive.org/details/evolutionselecte0000wrig/mode/2up?view=theater |url-access= registration |isbn=978-0-226-91053-6 |via= Internet Archive}}
• Wright 1983, [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1685743/pdf/ajhg00352-0209.pdf "Path Analysis in Genetic Epidemiology: A Critique"]

• [https://web.archive.org/web/20060208211310/http://www.harvardsquarelibrary.org/unitarians/wright-sewall.html Sewall Wright: Darwin's Successor—Evolutionary Theorist] by Edric Lescouflair and James F. Crow
• [http://www.amphilsoc.org/mole/view?docId=ead/Mss.Ms.Coll.60-ead.xml Sewall Wright Papers] at the American Philosophical Society
• {{Internet Archive author |search=(title:"Sewall Wright" OR creator:("Wright, Sewall, 1889-1988" OR creator:"Wright, Sewall"))}}
• {{MacTutor Biography|id=Wright_Sewall}}

{{Population genetics}}

{{Winners of the National Medal of Science|biological}}

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