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The reversal analysis you've mentioned doesn't take into account (not in the forms I've seen) the presence of high fertility subpopulations that will come to do

The reversal analysis you've mentioned doesn't take into account (not in the forms I've seen) the presence of high fertility subpopulations that will come to dominate larger low fertility populations eventually and drag everyone's fertility rate back up.

vidarh 6y ago
There are no "high fertility subpopulations" that maintain fertility rate irrespective of external situations. Research on immigration for example consistently show that immigrant populations adapt to local fertility levels within 1-2 generations. If anything, increasing immigration to developed countries would likely accelerate the reversal of population growth because of this effect. Furthermore, fertility drops as education increases and poverty decreases. This trend is consistent in every population where we can correlate economic development. E.g. here's the fertility rate for Niger [1], one of the poorest countries in the world. Even that has taken a sharp downturn as economic growth has started decoupling from uranium export (which previously dominated Niger's GDP, but provided very little benefit to the population). Niger, incidentally, has the highest fertility rate in the world, and is one of only 10 remaining countries with fertility rate above 5. As such such "high fertility subpopulations" are really high poverty, low education populations - currently countries categorised as "Least Developed Countries" by the UN have a fertility rate of 4. Sub-Saharan Africa is the only region of the world that remains above 4, but that too is dropping fast as most of the countries in the region are seeing solid economic growth. As poverty drops and education increases, fertility rates are dropping across the board, just not at the same rate. But even sub-Saharan African is headed for reversal. [1] https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?locations=NE https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...

vidarh 6y ago

There are no "high fertility subpopulations" that maintain fertility rate irrespective of external situations. Research on immigration for example consistently show that immigrant populations adapt to local fertility levels within 1-2 generations. If anything, increasing immigration to developed countries would likely accelerate the reversal of population growth because of this effect. Furthermore, fertility drops as education increases and poverty decreases. This trend is consistent in every population where we can correlate economic development. E.g. here's the fertility rate for Niger [1], one of the poorest countries in the world. Even that has taken a sharp downturn as economic growth has started decoupling from uranium export (which previously dominated Niger's GDP, but provided very little benefit to the population). Niger, incidentally, has the highest fertility rate in the world, and is one of only 10 remaining countries with fertility rate above 5. As such such "high fertility subpopulations" are really high poverty, low education populations - currently countries categorised as "Least Developed Countries" by the UN have a fertility rate of 4. Sub-Saharan Africa is the only region of the world that remains above 4, but that too is dropping fast as most of the countries in the region are seeing solid economic growth. As poverty drops and education increases, fertility rates are dropping across the board, just not at the same rate. But even sub-Saharan African is headed for reversal. [1] https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?locations=NE https://data.worldbank.org/indicator/SP.DYN.TFRT.IN?location...