> just reminds me how humans have been intelligent for many tens or hundreds of thousands of years
In terms of brain size, IIRC our brains were largest ~90k years ago, remained that size for ~60k years, incurred a slight shrinkage over ~20k years, then shrinkage quickened markedly since ~10k years ago (Ruff CB, et al. Body mass and encephalization in Pleistocene Homo, Nature 1997; 387: 173-176).
Of course, brain size /= intelligence or even brain efficiency. Hard to define intelligence anyway. Still a remarkable change to ponder.
I imagine its part of the 'civilization' package. More fuel-efficient, maturing to a more juvenile form, less aggressive, and more specialized brain? In a community you only have to learn a few specialized tasks, instead of needing to have all the skills?
Living in a dense village/town/city its important to be efficient especially with food. Its the fundamental limit on scaling. We don't all have to be warriors. Some sit and make clay pots or weave. A smaller, fuel-efficient model of citizen is a great advantage to a society.
In terms of brain size, IIRC our brains were largest ~90k years ago, remained that size for ~60k years, incurred a slight shrinkage over ~20k years, then shrinkage quickened markedly since ~10k years ago (Ruff CB, et al. Body mass and encephalization in Pleistocene Homo, Nature 1997; 387: 173-176).
Of course, brain size /= intelligence or even brain efficiency. Hard to define intelligence anyway. Still a remarkable change to ponder.