re: What history books in the future will cite for today as "they should've known"

It has to be the food we eat.

I can’t imagine any version of the future (or any stable, non-apocalyptic version at least) where we don’t look back on the 1970-2024 evolution of our food supply with anything other than absolute disgust.

With all the various artificial crud we’re jamming into everything we can, we are all functionally participating in the single largest biological experiment in human history. I suspect that experiment will eventually reveal a staggering level of self-harm that will mortify future generations. To the point that they will potentially view us as possessing a moral defect comparable to how we view the moral defectiveness of those who participated in the facilitation of slavery in past generations