Huxley's main co-respondents in the modern evolutionary synthesis are usually listed as Ernst Mayr, Theodosius Dobzhansky, George Gaylord Simpson, Bernhard Rensch, Ledyard Stebbins and the population geneticists J.B.S. Haldane, Ronald Fisher and Sewall Wright.<br> However, at the time of Huxley's book several of these had yet to make their distinctive contribution. Certainly, for Huxley, E.B. Ford and his co-workers in ecological genetics were at least as important.