Right. I don't disagree that male-male aggression played some role. I am just uncertain about whether it exerted a stronger selection pressure than the natural selection effect of hunting ability on survival.

The sudden adoption of weapons which required upper body strength doesn't provide much evidence to distinguish between the two.

And don't feel obligated to go out of your way to track down sources for me; I'd prefer to know more about this issue, ceteris paribus, but I don't think it's terribly important in the grand scheme of things.