His fears are justified based on his premise, but his hypothosis is only one of many possible ones. Regardless, it is a restatement of the chicken or egg dilemma, or, do we shape our environment or does it shape us? Was prehistoric man's basic nature really the same as ours today? Even without genetic meddling, will our basic nature be the same a million years from now?
That's actually an interesting question given the recent pronouncements by some scientists that humans have stopped evolving because we can now deal with any environmental change and we no longer choose our mates based on the principles used by our distant ancestors.