We'd only likely see huge consequences like that if we went outside the normal range of human variation. I agree that evolution would find single gene swaps wit

We'd only likely see huge consequences like that if we went outside the normal range of human variation. I agree that evolution would find single gene swaps with huge effects, but most of the variation available to us is over hundreds or thousands of genes making incremental effects. This is why I think we're probably first going go be able to effect marginal shifts in the overall distribution of these traits, not large jumps.