The Phenotypic Plasticity of Individual Difference

Nature vs. nurture thinking simply makes no sense: an entity can only respond to its environment via evolved capacities. Nonetheless, this binary reasoning is persistently attractive to the human mind, and is present in the theoretical foundations of all the major political tendencies. In this episode, we explore the persistent harm to our politics caused by an inability to reason about biology, and the many forms our confusion takes, particularly focusing on the eternally recurrent assumption that the more unvarying a behavior is, the more “biological” it is. We examine the Cold War ideological conflicts that pushed theorists on both sides of nature-nurture controversies to rigid—and not infrequently absurd—extremes, and see how phenotypic plasticity is reasserting itself in biology after decades of suppression, replacing outdated forms of evolutionary theory that involve genes “for” behaviors and ignore the means by which traits develop. In so doing, we assert the biology of social revolution: a description of the human capacity for behavioral variability that exists because of, rather than in opposition to, evolution.