Perhaps to become so technologically advanced and materially unconstrained that the rewards for aggression become so trivial relative to the risk that we abandon it as a tool.
Beam me up, Scotty.
"Back when I was a young boy all my aunts and uncles would poke me in the ribs at weddings saying your next! Your next! They stopped doing all that crap when I started doing it to them... at funerals!"