That is not what I learned when I was in graduate school. Look back to the early Homo species and note the brain sizes.
What you are suggesting is that the size increases and associated cultural advancements were accompanied by no increase in brain complexity. That is pretty dubious.
I think it helps the conservative cause to come to terms with human evolution being war driven. It means that we are violent to the core and need personal firearms and large amounts of military spending. It means the hippie vision for world peace is a bong pipe dream. It means leftists are really out to destroy America and we should stop tolerating their destructive behavior.
It's time to leave the ivory tower. Human means war maker.