It is disturbing to realize that all humans alive today are the direct descendants of the most successful committers of murder, enslavement, rape and genocide, and all historical injustice is just the documented tail end of success and failure in primate evolutionary competition.
The ones that can freely choose whether they cooperate or defect without letting on that they are internally unconstrained are going to be the most successful ones, but they depend on less conditional cooperators to thrive.