constanze:
Yet in your OP you asked not about outliers - exceptions - but normal people: the average population. So up til 200 years ago, Joe Average walked behind the plough without thinking (as farmhand or small-size farmer), and went to bed in the evening.
70 years ago, Joe could read the newspaper after work, but most people read the Sun equivalent.
So on average, I don’t see much change.
Wish I had the cite, but I recently read an article that made a convincing case that watching dumb tv shows and doing mundane office work today requires a lot more “brain power” so to speak than the analogous activities required in past decades.
Tom_Tildrum:
There was a theory kicking around for a while that communication between the two halves of the brain had not fully developed in ancient times, such that ancient people perceived insights from the right side of the brain as coming from a separate being, i.e., the voices of gods.
The theory shows up in science fiction now and then (Marvel Comics, Snow Crash ), but I assume it’s junk speculation. IIRC, it did not propose a specific mechanism by which human brains suddenly developed into the unified entity they are today. Besides, how could we possibly know that this was how the ancients thought?
This theory was propounded in Origin of Consciousness in the Breakdown of the Bicameral Mind by Julian Jaynes.
toadspittle:
It’s assumed that they were no less intellectually capable than today’s humans. The standard exhibit of why this would be so: You can take someone from Papua New Guinea, in a stone age society, whose population has been cut off from the rest of human civilization for tens of thousands of years, and train them to fly an airplane, etc. Unless there was some magical fairy dust in the air that increased the intelligence of all humans worldwide, you wouldn’t expect this sort of thing to happen.
In the same book, Guns, Germs and Steel , Jared Diamond says something like : The children (or grandchildren) of these primitive hunter-gatherers are now flying jet aircraft.