Fundamental behavior …

… Informal Inquiries: Abraham’s Curse (2008).

Anyone who has been a fight knows that, afterwards, you don't feel much or even any pain , that you're all pumped up and ready to party. Thinks a re different when you wake up the next day, of course. This would seem to suggest that the organism is primed for violence, presumably for reasons of survival. Something else we can blame Almighty Evolution for.