“…T he Russian-American evolutionary biologist Theodosius Dobzhansky has been the subject of considerable philosophical and historical scholarship, including how he integrated the methods of field naturalism and laboratory experimentation in ways that helped produce the Modern Evolutionary Synthesis and how he leveraged his biological expertise to defend liberal, cosmopolitan, and democratic values in the midst of the Second World War, the Cold War, and the problematization of race (Lewontin, 1974;Gould, Lewontin, 1979;Mayr, Provine, 1980;Beatty, 1987aBeatty, , 1987bPaul, 1987;Gould, 2002;Gannett, 2013;Subramanian, 2014;Yudell, 2014;Jackson, Depew, 2017). Moreover, Dobzhansky has been at the center of analyses on the institutionalization of genetics as a science in Brazil, where he spent most of his time outside of Russia and the US with the support of the Rockefeller Foundation (Glick, 1994(Glick, , 2008Cunha, 1998;Marinho, 2001;Pavan, Cunha, 2003;Araújo, 2004;Sião 2007;Formiga, 2008;Souza et al, 2013;Magalhães, Vilela, 2014;Souza, Santos, 2014;Santos, Silva, Gibbon, 2015). This article bridges both sets of literature by situating Dobzhansky's work in Brazil within the mid-twentieth-century science of genetic variation and the politics of diversity.…”