This paper investigates the application and interpretation of neural evolution in psychotherapeutic practice. Examining post-war mind-body therapies referring to the influential triune brain theory of Paul D. MacLean, this paper argues that evolutionary neuroscience provided an explanation for the emotional setup of humans. This allowed to naturalize a widespread unease with body and mind during the Cold War.
After World War II, the observation of simians killing each other gave rise to the concept of the ‘killer ape’ in anthropology, paleontology, primatology, and zoology: the idea being that humanity’s success rested upon the capacity for murder, the emotional inclination to aggression. Alongside the ‘killer ape theory’, the triune brain theory, or in more colloquial speech the ‘lizard brain’ theory, represented an alternative neurological answer; the human brain consisted of three sub-systems which represented the remains of evolutionary antecedents, each of them responsible for specific mental abilities. Although few scientists bought this reductionist model, its applicability and simplicity caused broad dissemination and guaranteed a place in psychological textbooks up into the twenty-first century. A closer look at psychotherapeutic practices after A.H. Maslow, A. Ellis, and R.D. Laing exemplifies the crucial role of evolutionary neuroscience in post-war thinking about body and mind and adds to recent historical work on Cold War rationality.