Post-traumatic stress disorder and post-combat reintegration: An evolutionary model

The medical model and mental health stigma frame post-traumatic stress disorder (PTSD) as an essential malfunction. However, in this chapter the author argues that what are regarded as PTSD sequelae exist today because they are based on survival adaptations, helping human ancestors avoid predation, cope with aggressive in-group members, and survive violent inter-group conflicts. While distressing to the experiencer, PTSD-related interpersonal difficulties, as well as behavioral, cognitive, and comorbid symptomology, have ancestral survival utility. In particular, combat-related PTSD and the associated difficulties soldiers face reintegrating into civilian life are illuminated by an evolutionary framing of PTSD, evolved male coalitionary psychology, and the mismatch between the evolutionary past and life in modern, peacetime, civilian environments. Evolutionary explanations of PTSD can help reduce mental health stigma, and increase rates of engagement and completion of evidence-based psychotherapies.