I'd say there was high variance in the past, like there is today But the diet that Americans eat today is worse than that of the past, adjusted for income i.e

I'd say there was high variance in the past, like there is today But the diet that Americans eat today is worse than that of the past, adjusted for income i.e. we are > 1000x wealthier now, but eat poorer quality food than somebody with the same wealth 1000, 2000, or even 10,000 years ago. This is because the entire food industry has "scaled" and become economically optimized It's mistake to think we can't regress, or haven't regressed and forgotten valuable knowledge -- architecture is another good example