Digestion is quickly shut down during stressโฆThe parasympathetic nervous system, perfect for all that calm, vegetative physiology, normally mediates the actions of digestion. Along comes stress: turn off parasympathetic, turn on the sympathetic, and forget about digestion.
Robert M. SapolskyBrains distinguish between an Us and a Them in a fraction of a second. Subliminal processing of a Them activates the amygdala and insular cortex, brain regions that are all about fear, anxiety, aggression, and disgust.
Robert M. SapolskyImportantly, rather than promoting aggression, testosterone promotes whatever is needed to maintain status when challenged.
Robert M. SapolskyEssentially, we humans live well enough and long enough, and are smart enough, to generate all sorts of stressful events purely in our heads.
Robert M. Sapolsky