I’ve heard that North Koreans are 1 to 3 inches shorter than South Koreans. Assuming this is true, does anyone know how much taller or shorter one generation of people can get?
Does it follow that all societies that improve their health conditions will get taller over time (up to some genetic limit)?
Most of the difference in height is due to malnutrition, there’s probably no genetic component. So if you took a North Korean baby and gave them proper nutrition they would grow the same height as a South Korean baby. There hasn’t been enough time for any serious genetic shift to happen.
So, one generation in this case.
I suspect most western nations are close to or at their genetic height potential right now.
From what I have read, I agree that it’s malnutrition. Around 2 million North Koreans died from it in the 90’s.
Not sure which book it was (perhaps Nothing to Envy), but I believe that NK reduced the size restriction for new recruits for the Army. I think it’s 5 feet now, where it was 5’2".
In Japan, average heights have risen dramatically in just two generations. According to an article from the New York Times:
Theoretically, very quickly, if a stringent program of infanticide is enforced to restrict all surviving children to carry a genetic predisposition to great height.
Societies, to varying degrees, favor people of a certain height, for reasons which may be intentional or inflicted on them by circumstance. On an island where the only ladder of success is to become a professional basketball player, the average height would increase very quickly, as shorter offspring would be relegated to economic marginality.
There is the famous (but possibly apocryphal) report of an island on which do-gooders significantly improved the nutrition very quickly. The sudden increase in the birth weight of fetuses resulted in a high obstetric mortality rate, as women had evolved birth canal and pelvic sizes intolerant of such large infants.