How could this possibly be implemented? Honestly there would have to be such a massive stopper put in human ingenuity. How could we let natural selection reclaim us? Stop using tools and medicine? Go back to living in caves? You can reach for the stars by "progressing" with your environment, or you can build a rocket and fly to them. Humans didn't wait for hundreds of thousands of years of natural selection to provide them with a warm fur coat to protect against the cold, they went out and killed a bear and wore its skin.