Sir Arthur Keith (February 5, 1866 - January 7, 1955) was a Scottish anatomist and anthropologist, who became a fellow of the Royal College of Surgeons of England and Hunterian Professor and conservator of the Hunterian Museum of the Royal College of Surgeons in London (not to be confused with the Hunterian Museum Glasgow Scotland; the two were founded by brothers). A leading figure in the study of human fossils, he became President of the Royal Anthropological Institute. The latter role stimulated his interest in the subject of human evolution, leading to the publication of his book A New Theory of Human Evolution, in which he supported the idea of group selection. Where others had postulated that physical separation could provide a barrier to interbreeding, allowing groups to evolve along different lines, Keith introduced the idea of cultural differences as providing a mental barrier, emphasising territorial behaviour, and the concept of the 'in-group' and 'out-group'. Man had evolved, he claimed, through his tendency to live in small competing communities, a tendency which was at root determined by racial differences in his 'genetic substrate'. Writing just after World War II he particularly emphasised the racial origins of anti-Semitism, and in 'A New Theory of Evolution' he devoted a chapter to the topics of anti-Semitism and Zionism in which he argued that Jews live by a 'dual code'