The British biologist W.D. Hamilton (1936 -) has been one of the most influential evolutionary theorists over the last thirty years and a leading figure in dismantling group selection assumptions, which until recently had been widely unquestioned.

Hamilton is best known for his theory of kin selection, which he originated while still a student and expanded upon in a series of classic papers in the early 1960s. Since then, he has worked on, and made important contributions to, a number of problematic issues in evolutionary biology:

• The importance of parasites in explaining the maintenance of sexual reproduction.

• Over-elaborate displays by males, such as the peacock's tail, as a means of advertising low levels of parasite infection.