Pulling a gun's trigger can be an appalling act. But if it is suicidal drawing fire to save someone, it has an utterly different meaning. Placing your hand on someone's arm can be an act of deep compassion or the first step of betrayal. The punch line? It's all about context, and the biology of context is vastly more complicated than the biology of the behavior itself.

We’ve evolved to be smart enough to make ourselves sick.

What happened in the milliseconds before a behavior to cause it? That's in the neurobiological realm.

What happened during the minutes before? That's the realm of sensory stimuli of the nervous system.

We all seek out stress. We hate the wrong kinds of stress but when it's the right kind, we love it - we pay good money to be stressed by a scary movie, a roller coaster ride, a challenging puzzle.

Give lab rats oxytocin and, according to that meme, they get better at talking about their feelings and sing like Joan Baez.

Digestion is quickly shut down during stress…The 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.