In 1962, anthropologist Carleton Coon argued in The Origin of Races that some human races had evolved further than others. Among his most vocal critics were geneticist Theodosius Dobzhansky and anthropologist Ashley Montagu, each of whom had known Coon for decades. I use this episode, and the long relationships between scientists that preceded it, to argue that scientific research on race was intertwined not only with political projects to conserve or reform race relations, but also with the relationships scientists shared as colleagues. Demarcation between science and pseudoscience, between legitimate research and scientific racism, involved emotional as well as intellectual labor.