Evolutionary Perspective

“What I had was classic short-term PTSD. From an evolutionary perspective, it’s exactly the response you want to have when your life is in danger: you want to be vigilant, you want to avoid situations where you are not in control, you want to react to strange noises, you want to sleep lightly and wake easily, you want to have flashbacks and nightmares that remind you of specific threats to your life, and you want to be, by turns, angry and depressed. Anger keeps you ready to fight, and depression keeps you from being too active and putting yourself in more danger. Flashbacks also serve to remind you of the danger that’s out there—a “highly efficient single-event survival-learning mechanism,” as one researcher termed it. All humans react to trauma in this way, and most mammals do as well. It may be unpleasant, but it’s preferable to getting killed.”
― Sebastian Junger, Tribe: On Homecoming and Belonging