- Sewall Wright
Sewall Green Wright (
December 21, 1889– March 3, 1988) was an American geneticistknown for his influential work on evolutionary theoryand also for his work on path analysis. With R. A. Fisherand J.B.S. Haldane, he was a founder of theoretical population genetics. He is the discoverer of the inbreeding coefficientand of methods of computing it in pedigrees. He extended this work to populations, computing the amount of inbreeding of members of populations as a result of random genetic drift, and he and Fisher pioneered methods for computing the distribution of gene frequenciesamong populations as a result of the interaction of natural selection, mutation, migration and genetic drift. The work of Fisher, Wright, and Haldane on theoretical population genetics was a major step in the development of the modern evolutionary synthesisof genetics with evolution. Wright also made major contributions to mammalian genetics and biochemical genetics.
Sewall Wright was born in Melrose,
Massachusettsto Philip Green Wright and Elizabeth Quincy Sewall Wright. The family moved three years later after Philip accepted a teaching job at Lombard College, a Universalistcollege in Galesburg, Illinois.
He was the oldest of three gifted brothers – the others being the
aeronautical engineer Theodore Paul Wrightand the political scientist Quincy Wright. From an early age Wright had a love and talent for mathematicsand biology. Wright attended Galesburg High Schooland graduated in 1906. He then enrolled in Lombard Collegewhere his father taught, to study mathematics. He was influenced greatly by Professor Wilhelmine Entemann Key, one of the first women to receive a Ph.D. in biology. Wright received his Ph.D. from Harvard University, where he worked with the pioneering mammalian geneticist William Ernest Castleinvestigating the inheritance of coat colors in mammals. He worked for the U.S. Department of Agricultureuntil 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, the Balzan Prize, and the Darwin Medalof the Royal Society. He was a member of the National Academy of Scienceand a Foreign Member of the Royal Society.
Wright married Louise Lane Williams (1895-1975) in 1921. They had three children: Richard, Robert, and Elizabeth.
cientific achievements and credits
His papers on
inbreeding, mating systems, and genetic driftmake him a principal founder of theoretical population genetics, along with R. A. Fisherand J. B. S. Haldane. Their theoretical work is the origin of the modern evolutionary synthesisor neodarwinian synthesis. Wright was the inventor/discoverer of the inbreeding coefficientand F-statistics, standard tools in population genetics. He was the chief developer of the mathematical theoryof genetic drift, which is sometimes known as the Sewall Wright effect, cumulative stochastic changes in gene frequencies that arise from random births, deaths, and Mendelian segregations in reproduction. Wright was convinced that the interaction of genetic driftand 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 fitness landscapes. Onthese landscapes mean population fitness was the height, plotted against horizontal axes representing the allele frequencies or the average phenotypes of the population. Natural selectionwould lead to a population climbing the nearest peak, while genetic driftwould cause random wandering.
Wright's explanation for
stasiswas that organisms come to occupy adaptive peaks. 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 driftif the population is small enough. If a species was divided into small populations, some could find higher peaks. If there was some gene flowbetween the populations, these adaptations could spread to the rest of the species. This was Wright's shifting balance theoryof 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 strongly influenced
Jay Lush, who was the most influential figure in introducing quantitative geneticsinto animal and plant breeding. Wright's statistical method of path analysis, 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. Such was hisreputation that he was often credited with reviews that he did not write.
He did major work on the genetics of
guinea pigs, 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.
Wright and philosophy
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 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.
Wright and Fisher were the key figures in the
neodarwinian synthesisthat brought genetics and evolution together. Their work was essential to the contributions of Dobzhansky, Mayr, Simpson, Julian Huxley, and Stebbins. The neodarwinian 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.
Since Wright developed the methods used for assessing the degree of inbreeding and its effects, it is notable that his own parents were first cousins. As a child he helped his father and brother print and publish an early book of poems by his father's student
* Crow, James F. (1988) [http://www.genetics.org/cgi/reprint/119/1/1.pdf "Sewall Wright (1889-1988)"] "Genetics" 119 (1): 1-4.
* Crow, James F. and W. F. Dove. (1987) [http://www.genetics.org/cgi/reprint/115/1/1.pdf "Sewall Wright and physiological genetics"] "Genetics" 115 (1): 1-2.
* Ghiselin, Michael T. (1997) [http://books.google.com/books?ie=UTF-8&hl=en&vid=ISBN0791434672 "Metaphysics and the Origin of Species"] . NY: SUNY Press.
* Hill, William G. (1996) [http://www.genetics.org/cgi/reprint/143/4/1499.pdf "Sewall Wright's 'Systems of Mating'"] "Genetics" 143 (4): 1499-506.
*cite book | author=Provine, William | date=1986 | title=Sewall Wright and Evolutionary Biology | publisher= University of Chicago Press |id=ISBN 0-226-68473-3
*Wright, Sewall (1932) [http://www.blackwellpublishing.com/ridley/classictexts/wright.asp "The roles of mutation, inbreeding, crossbreeding and selection in evolution"] "Proc. 6th Int. Cong. Genet." 1: 356–366.
*cite book | author=Wright, Sewall | date=1986 |title=Evolution: Selected papers | publisher=University of Chicago Press|id=ISBN 0-226-91053-9
Books by Wright
*cite book | author=Wright, Sewall | date=1984| title= Evolution and the Genetics of Populations: Genetics and Biometric Foundations v. 1 (Genetic & Biometric Foundations); New Edition | publisher=University of Chicago Press | id=ISBN 0-226-91038-5
*cite book | author=Wright, Sewall | date=1984| title= Evolution and the Genetics of Populations: Genetics and Biometric Foundations v. 2 (Theory of Gene Frequencies); New Edition | publisher=University of Chicago Press | id=ISBN 0-226-91039-3
*cite book | author=Wright, Sewall | date=1984| title= Evolution and the Genetics of Populations: Genetics and Biometric Foundations v. 3 (Experimental Results and Evolutionary Deductions); New Edition | publisher=University of Chicago Press | id=ISBN 0-226-91040-7
*cite book | author=Wright, Sewall | date=1984| title= Evolution and the Genetics of Populations: Genetics and Biometric Foundations v. 4 (Variability within and Among Natural Populations); New Edition | publisher=University of Chicago Press | id=ISBN 0-226-91041-5
* [http://www.harvardsquarelibrary.org/unitarians/wright-sewall.html Sewall Wright: Darwin's Successor—Evolutionary Theorist] by Edric Lescouflair and James F. Crow
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Sewall Wright — Sewall Green Wright (* 21. Dezember 1889 in Melrose (Massachusetts); † 3. März 1988 in Madison (Wisconsin)) war ein amerikanischer Theoretischer Biologe und Genetiker, der zusammen mit Ronald Fisher und J. B. S. Haldane in den 1920er Jahren die… … Deutsch Wikipedia
Sewall Wright — Sewall Green Wright (21 décembre 1889 3 mars 1988) est un généticien américain, connu pour ses travaux sur la théorie de l évolution, et aussi pour son travail sur l analyse de chemin, en statistiques. Il a reçu la médaille Darwin en 1980.… … Wikipédia en Français
Sewall-Wright-Effekt — Als Gendrift (das niederdeutsche Drift ist verwandt mit dem deutschen treiben) (auch Alleldrift oder Sewall Wright Effekt) bezeichnet man in der Populationsgenetik eine zufällige Veränderung der Genfrequenz innerhalb des Genpools einer Population … Deutsch Wikipedia
sewall wright effect — ˈsüəlˈrīt noun Usage: usually capitalized S&W Etymology: after Sewall Wright b1889 American geneticist : differentiation within a group arising from chance fixation of nonadaptive characters in small isolated populations … Useful english dictionary
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Wright, Sewall — born Dec. 21, 1889, Melrose, Mass., U.S. died March 3, 1988, Madison, Wis. U.S. geneticist. He earned his doctorate at Harvard University. His earliest studies included investigation of the effects of inbreeding and crossbreeding on guinea pigs,… … Universalium
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