I'd like to start giving people the option of commenting on shorter Cold Takes pieces (which I don't cross-post here or provide audio for). I'm going to use this post for that: I will generally leave a comment for each piece, and people can leave their comments as replies to that.
I was pretty struck by how per capita output isn't obviously going down, and it's only when you do the effective population estimates that it does.
Could this suggest a 4th hypothesis: the 'innate genius' theory: about 1 in 10 million people are geniuses, and at least since around 1400, talent spotting mechanisms were good enough to find them, so the fraction of the population that was educated or urbanised doesn't make a difference to their chances of doing great work.
I think I've seen people suggest this idea - I'm curious why you didn't include it in the post.