How did Homo sapiens manage to cross this critical threshold, eventually founding cities comprising tens of thousands of inhabitants and empires ruli… - Yuval Noah Harari

You might object that people were asked ‘What do you think?’ rather than ‘What do you feel?’, but this is a common misperception. Referendums and elections are always about human feelings, not about human rationality. If democracy were a matter of rational decision-making, there would be absolutely no reason to give all people equal voting rights – or perhaps any voting rights. There is ample evidence that some people are far more knowledgeable and rational than others, certainly when it comes to specific economic and political questions.

The currency of evolution is neither hunger nor pain, but rather copies of DNA helixes. Just as the economic success of a company is measured only by the number of dollars in its bank account, not by the happiness of its employees, so the evolutionary success of a species is measured by the number of copies of its DNA.

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.