Where did I read this recently? Human evolution has slowed significantly with the advent of social safety nets like cities and laws which protect all people, regardless of their genetic deficiencies. These days everyone survives, even the slow, the blind, the weak, the ugly. Evolutionary forces which might have conspired to continually improve us now make it possible for those who would have been weeded out by sabre-tooth tigers or those who would have failed to procreate because of unattractive figures or personalities to find mates (often equally unworthy of climbing the Darwinian ladder) and pass their flawed DNA onto the next generation. Medical advances like LASIK eye surgery allow people to overcome or at least compensate for their weaknesses.
Is that not depressing? The most advanced society creates the most diluted gene pool. Look around you--this may be as good-looking and smart a crew as you'll see.