There is some evidence that the size of the average sapiens brain has actually decreased since the age of foraging. Survival in that era required superb mental abilities from everyone. When agriculture and industry came along people could increasingly rely on the skills of others for survival, and new “niches for imbeciles” were opened up. You could survive and pass your unremarkable genes to the next generation by working as a water carrier or an assembly line worker. Yuval Noah Harari – Sapiens.