[constantius]

Life expectancy didn't change that much, what changed is infant mortality.

And for cognitive ability: plenty of firsthand accounts from Enlightenment thinkers about thesuperior reasoning abilities of average members of hunter-gatherer/American Indian tribes compared to the typical European at the time, and they arguably already had better access to nutrition/education/healthcare.

Cognitive ability is for sure related to some extent to these factors, but actual practice of reasoning (through public debates, leisure time, storytelling) seems to have been much more influential on the actual realisation of cognitive potential, and I'm not sure there'd be a stark difference between a typical human today, or even a typical Westerner, vs a typical Roman citizen.

[jleyank]

Plato begs to differ re: philosophy. Ancient people could memorize staggeringly more than folks today. They probably also paid (far) more attention to their surroundings. Like Rangers in D&D, they could read blades of grass and state what/when walked by...

[pseudalopex]

> Life expectancy didn't change that much, what changed is infant mortality.

Life expectancy means at birth commonly. Life expectancy changed because infant and child mortality changed.