Imo Japan is one of the more illuminating examples on this topic:
Japan had a TFR of 5 in the 1930s. It’s been only 3 generations since Japan’s TFR began to fall, and France took 5 to stablise around the current level (1830s-1980s). I agree that the trend since 2005 is too short term to be sure, but it’s interesting to note! The above modelling suggests that a faster fertility transition should result in a faster bounceback—the lower the TFR the more adaptive high-TFR genes + cultures will be relatively.
The fertility transition hit East Asia harder and faster than it did Europe. There’s merit to the theory that it’s because Europe had a slower transition to today’s mainstream fertility-surpressing universal culture (technological advancement, enlightenment values. women’s lib etc), since much of these cultural changes were developed in the West (consider the analogy to megafauna in Africa).
It’s extremely difficult to quantify this sort of thing but it does support a model where both genes and culture are load-bearing inputs to TFR. In countries where culture propped up fertility one way or another there could be said to be a cultural fertility overhang, and when these forces were removed TFR naturally cratered in the short term. Where countries had less cultural overhang, or a slower transition from high-TFR culture to low-TFR culture, the transition was less dramatic because there was time for cultural counter-developments or genetic selection to act.
The example of Sth Korea (TFR >5 until the 60s) supports some of these theories. The timing is especially interesting—the 60s were a major leap forward in progressive cultural hegemony, and Sth Korea (an extremely poor society prior) copped that right in the face after the Korean War. The idea is that the speed of TFR-decline is related to the severity of cultural change—makes sense to me.
An optimistic Sth Korean pro-natalist could interpret this current ultra-low TFR period as evidence of an extremely effective ‘weeding’ process which is sure to be followed by a period of high fertility preferences as the most enthusiastic ‘breeders’ will be all that remain!
Note: When I refer to culture above I take the expansive definition which includes technology, wealth, social changes—ie. anything that isn’t genetic.
Imo Japan is one of the more illuminating examples on this topic:
Japan had a TFR of 5 in the 1930s. It’s been only 3 generations since Japan’s TFR began to fall, and France took 5 to stablise around the current level (1830s-1980s). I agree that the trend since 2005 is too short term to be sure, but it’s interesting to note! The above modelling suggests that a faster fertility transition should result in a faster bounceback—the lower the TFR the more adaptive high-TFR genes + cultures will be relatively.
The fertility transition hit East Asia harder and faster than it did Europe. There’s merit to the theory that it’s because Europe had a slower transition to today’s mainstream fertility-surpressing universal culture (technological advancement, enlightenment values. women’s lib etc), since much of these cultural changes were developed in the West (consider the analogy to megafauna in Africa).
It’s extremely difficult to quantify this sort of thing but it does support a model where both genes and culture are load-bearing inputs to TFR. In countries where culture propped up fertility one way or another there could be said to be a cultural fertility overhang, and when these forces were removed TFR naturally cratered in the short term. Where countries had less cultural overhang, or a slower transition from high-TFR culture to low-TFR culture, the transition was less dramatic because there was time for cultural counter-developments or genetic selection to act.
The example of Sth Korea (TFR >5 until the 60s) supports some of these theories. The timing is especially interesting—the 60s were a major leap forward in progressive cultural hegemony, and Sth Korea (an extremely poor society prior) copped that right in the face after the Korean War. The idea is that the speed of TFR-decline is related to the severity of cultural change—makes sense to me.
An optimistic Sth Korean pro-natalist could interpret this current ultra-low TFR period as evidence of an extremely effective ‘weeding’ process which is sure to be followed by a period of high fertility preferences as the most enthusiastic ‘breeders’ will be all that remain!
Note: When I refer to culture above I take the expansive definition which includes technology, wealth, social changes—ie. anything that isn’t genetic.