I've found reductionist social Darwinism lacks explanatory for these phenomena.
Why are you so sure that it was competition and not cooperation that ensured the strength of a tribe?
Or to put it another way, could cooperation, even cooperation with those you dislike, also lead to a materially successful tribe?
Just-so stories have that trait.
"There's a huge evolutionary advantage in calling attention to good actors (someone behaving a way which is advantegeous to the tribe), because that person will have that behaviour reinforced, and the social proof will motivate others to follow suite. This helps the group."
And being aware of some dynamic is totally different from being free or above its influence.
http://www.craigflint.com/graphics/illustrations/justsoeleph...