The symptoms of trauma-related disorders include both psychological and physiological signs. Evolutionary perspectives of trauma-related disorders have related the primitive mechanisms such as sensitization and dissolution to the stress responses for survival (Baldwin, 2013). The psychological and physiological reactions are considered adaptive responses to diverse life-threatening dangers. For example, as the major emotion of post-traumatic stress disorder (PTSD), fear may trigger defensive behaviors for the purpose of survival (Cantor, 2009).
Trauma-related physical symptoms such as freeze or collapse may be associated with the defensive responses. Such understanding may suggest that stress responses can become the focus of care for trauma-related disorders (Baldwin, 2013). From the evolutionary perspective, defensive behaviors are connected to predation pressure, environmental threats, and conspecific (same species) pressure (Cantor, 2009). These factors need to be considered for a better understanding of post-traumatic stress disorder (PTSD). The defensive response may progress from avoidance to attentive immobility, from withdrawal to aggressive defense, and from appeasement to tonic immobility (Cantor, 2009).
Individual differences in perceptual factors such as predictability and controllability, together with neuronal plasticity and various defensive strategy recalibrations may contribute to the different responses to stress and trauma. Such analysis may help explain the facts that some individuals would develop PTSD while other people do not have the problem even under the same circumstances. The understanding of such mechanisms may be critical for the development of personalized therapeutic strategies for PTSD.
Baldwin DV. Primitive mechanisms of trauma response: an evolutionary perspective on trauma-related disorders. Neurosci Biobehav Rev. 2013 Sep;37(8):1549-66. doi: 10.1016/j.neubiorev.2013.06.004.
Cantor C. Post-traumatic stress disorder: evolutionary perspectives. Aust N Z J Psychiatry. 2009 Nov;43(11):1038-48. doi: 10.3109/00048670903270407.