This paper will discuss, cautiously with respect to causal hypotheses, the changing ideological context of the Modern Synthesis. In the 1940s and 50s, the Synthesis showed, and to some extent was formed to show, that advanced evolutionary science could put to rest the racism and eugenics that had embarrassed, challenged, and in some cases compromised geneticists and evolutionists. By the early 1960s it had succeeded in taking these themes off the table by treating culture, in anthropologists' sense, as the genes' finest product.[1] The ideological advantages of this theorem may have played a role in placing the burden of proof onto Muller's classical view of population structure and in creating a presumption for Dobzhansky's balancing view in spite of its empirical weakness. With this consensus achieved, the Synthesis turned to the evolution of lifecycles, relationships among species in islands (seen as quasi-laboratories), and behavioral ecology. Research programs in these areas used calculi developed to facilitate wary cooperation in Cold War nuclear brinksmanship. They interacted with each other in this larger context. Trouble only occurred when use of these calculi was viewed by some as threatening the concept of culture that had been allaying the old worries. Not surprisingly, the old worries came back during the ideologically hypertrophic Viet Nam period.