Sir Ronald Aylmer Fisher (1890 - 1962) was a British mathematician and geneticist whose book, The Genetical Theory of Natural Selection (1930) proved that Mendelian genetics is an essential underlying mechanism of Darwiniam evolution. His work laid the foundations for statistical analysis of all subsequent experiments in the life sciences.

Fisher's legacy to evolutionary biology includes the following areas:

• He described a process called runaway sexual selection to explain exaggerated characters of organisms such as the peacock's tail.

• He explained why sexual species maintain a sex ratio of roughly 50:50.

• He developed a model of adaptive evolution which describes the relationship between the form of a character and its fitness.

• He proposed that accelerated evolution is an advantage of sexual reproduction that may outweigh the enormous costs of sex.

This photograph of R.A. Fisher was taken in 1912.