Posttraumatic stress disorder and the Neuroevolutionary Time-depth Principle
Leo Sher, M.D.
Our theoretical work, “Posttraumatic stress disorder in war veterans: a discussion of the Neuroevolutionary Time-depth Principle” was published 10 years ago in the September 2010 issue of the Journal of Affective Disorders (1).
The “Neuroevolutionary Time-depth Principle” of innate fears suggests that high rates of posttraumatic stress disorder (PTSD) after combat exposure can be due to the fact that this fear-stress response appeared as a reaction to inter-group male-to-male and intra-group killings after the rising of population densities in the Neolithic period.
War is only one of the ways in which violence (human aggression) is expressed. The features of war have varied since its emergence in the Neolithic period, and the stressors to which war veterans and the general population are exposed have rapidly changed during the last one hundred years. Hence, war is not a uniform and unchanged phenomenon. Not all war stressors are similar because some of them are known to lead to PTSD more than others.
PTSD rates following exposure to lethal inter-group violence (combat, war-zone exposure or intentionally caused disasters such as terrorism, and persistent trauma involving cruelty) are usually 5–10 times higher than rates following large-scale natural disasters such as forest fires, floods, hurricanes, volcanic eruptions, and earthquakes.
Prevalence data of PTSD deeply vary from one country to another, even in groups exposed to similar stressors. Psychosocial narratives deeply influence our biological response to trauma and violence, shaping the genotypical response to trauma. Great differences in prevalence may be in part due to this fact.
Personal preconceptions and socio-cultural interests may also be playing a critical role in the theories developed to explain the nature of our response to violence. A single theory never gives comprehensive answers to complex questions.
1. Braquehais MD, Sher L. Posttraumatic stress disorder in war veterans: a discussion of the Neuroevolutionary Time-depth Principle. J Affect Disord. 2010 Sep;125(1-3):1-9. doi: 10.1016/j.jad.2009.08.008. Epub 2009 Sep 5. PMID: 19733913.