What was the average life span back then? An important point that is missing in the article.
A thought that crossed my mind, perhaps in these early civilizations elders who were losing it would be put out to pasture.
“What was the average life span back then?”
Basically 60+, but only if you made it to age 20, which was less than half of the people born, but then the birthrate was far higher than today’s birthrate.
The main reason for not people not getting dementia was that no one took statins, and thus their brains received the high levels of cholesterol needed to operate properly.
People who lived 500BC tended to live to 70 - IF they survived childhood and didn’t die from wars.