I think you underestimate how powerful this mechanism can be. Take 20 years for one generation, ie. 100 years is 5 generations. We're talking about roughly time

I think you underestimate how powerful this mechanism can be. Take 20 years for one generation, ie. 100 years is 5 generations. We're talking about roughly time from 800 CE, that is 60 generations. Imagine taking smartest people to reproduce, then taking smartest from their kids and so on - 60 times. You will see an effect. You can optimize on anything, ie. "time you can dive underwater" you will see the difference compared to other people after 60 generations, see https://www.sciencemag.org/news/2018/04/indonesian-divers-have-evolved-bigger-spleens-hunt-underwater https://www.sciencemag.org/news/2018/04/indonesian-divers-ha...