The two factors this suggests to me, over that time period, are “increase in TV watching among young children” and “change in diet toward highly processed foods high in carbohydrates”. This hypothesis would also predict the finding that myopia increased faster among blacks than among whites, since these two factors have been stronger in poorer urban areas than in wealthier or more rural ones.
It didn’t begin then, but it certainly continued to shift in that direction. IIRC from The Omnivore’s Dilemma, it was under Nixon that massive corn subsidies began and vast corn surpluses became the norm, which led to a frenzy of new, cheap high-fructose-corn-syrup-based products as well as the use of corn for cow feed (which, since cows can’t digest corn effectively, led to a whole array of antibiotics and additives as the cheap solution).
Upshot: I’d expect that the diet changes in the 1970s through 1990s were quite substantial, that e.g. sodas became even cheaper and more ubiquitous, etc.
The two factors this suggests to me, over that time period, are “increase in TV watching among young children” and “change in diet toward highly processed foods high in carbohydrates”. This hypothesis would also predict the finding that myopia increased faster among blacks than among whites, since these two factors have been stronger in poorer urban areas than in wealthier or more rural ones.
Hypotheses aside, good find!
Has this happened since 1970?
(The article suggests “computers and handheld devices.”)
It didn’t begin then, but it certainly continued to shift in that direction. IIRC from The Omnivore’s Dilemma, it was under Nixon that massive corn subsidies began and vast corn surpluses became the norm, which led to a frenzy of new, cheap high-fructose-corn-syrup-based products as well as the use of corn for cow feed (which, since cows can’t digest corn effectively, led to a whole array of antibiotics and additives as the cheap solution).
Upshot: I’d expect that the diet changes in the 1970s through 1990s were quite substantial, that e.g. sodas became even cheaper and more ubiquitous, etc.