Sir Ronald Aylmer Fisher (17 February 1890 – 29 July 1962) was a British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic. For his work in statistics, he has been described as "a genius who almost single-handedly created the foundations for modern statistical science" and "the single most important figure in 20th century statistics". In genetics, his work used mathematics to combine Mendelian genetics and natural selection; this contributed to the revival of Darwinism in the early 20th-century revision of the theory of evolution known as the modern synthesis. For his contributions to biology, Fisher has been called "the greatest of Darwin’s successors".
From 1919, he worked at the Rothamsted Experimental Station for 14 years; there, he analysed its immense body of data from crop experiments since the 1840s, and developed the analysis of variance (ANOVA). He established his reputation there in the following years as a biostatistician.
Together with J. B. S. Haldane and Sewall Wright, Fisher is known as one of the three principal founders of population genetics. He outlined Fisher's principle, the Fisherian runaway and sexy son hypothesis theories of sexual selection. His contributions to statistics include promoting the method of maximum likelihood and deriving the properties of maximum likelihood estimators, fiducial inference, the derivation of various sampling distributions, founding principles of the design of experiments, and much more.
Fisher held strong views on race and eugenics, insisting on racial differences. Although he was clearly a eugenicist, there is some debate as to whether Fisher supported scientific racism (see ). He was the Galton Professor of Eugenics at University College London and editor of the Annals of Eugenics.
Fisher was born in East Finchley in London, England, into a middle-class household; his father, George, was a successful partner in Robinson & Fisher, auctioneers and fine art dealers.