Somebody seems out of place in a group = killed or left starving or even sacrificed to the Gods in order to please them and get a good harvest.
Now we are in a different time not every moment is a do or die moment, we also only have a certain amount of "do or die cognition" built within us, when we run out of it , that's bad because we might need it in the future.
The problem is that we used to live very short and violent lives so the rational thing to do was to always be in "do or die" mode until you eventually ran out of luck and died around 30, or if you were lucky 35. And so it is the same happening right now.
At this point I think that people are justified when they load up on alcohol, weed and XanaX (America is one nation under XanaX). As the calming chemicals are used to fight the "do or die" tendencies that harass us daily.