I agree with the central premise of your argument, however, I disagree on your views about the role of civilization in the natural selection. If the natural selection is a fully random process, it takes much, much longer for those random mutations to become an advantage in the reproductive process.
However, if the selection is not natural but guided, that transformation can take place within a much shorter time, usually a few generations. Animal breeding is a case in point. Reproduction of animals with certain biological traits is actively encouraged, while reproduction of animals who do not have these traits - discouraged. By a different species, to be sure, but the process is clearly directional.
Civilization is nothing but such selective breeding of human animals. Civilizational norms of what is good and desirable translate into different probabilities of reproduction through various mechanisms, ranging from selective mating to infanticide. If it were not for cultural norms prohibiting "miscegenation" - members of the US population would have very different physical characteristics than they currently do - they would be multi-racial as opposed to mostly Blacks or mostly Whites.
I would go as far as saying that social groups that actively encourage certain behavior - be it physical aggression or artistic pursuits - actively encourage breeding of individuals with characteristics that are favorable for these pursuits.
Wojtek