The Fertility J-Curve

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Via the Demography Matters blog, Russian birthrate seems to have recovered:

By 2009, the official TFR had risen to 1.537, 1.417 in urban areas and 1.900 in rural areas. Both urban and rural TFRs rose by about the same amount from 2000 to 2009, about 0.330. Vital statistics for 2010 were just released by the national statistics office, GOSKOMSTAT, also known as ROSTAT. The birth rate continues to rise but not as sharply in the past two years as it did in 2007 and 2008. One must wonder if the slower increase in the past two years suggests the birth rate revival may be running out of steam or that it may be due to the global recession. But natural decrease is now but one-fourth of what is was in 2000 and that is a truly dramatic turnaround. The TFR can be estimated at about 1.56 for 2010 although we must wait for the official TFR when it is released later this year. Births for January 2011 have also been released and those are down slightly from January 2010, 131,454 from 132,371. One month hardly defines a trend but I thought I’d pass that along.

This is still below replacement, but is substantially higher than the estimates from 2000, when the birth rate per woman bottomed out to roughly 1.2. At the time, everyone was extrapolating a near-certain birth spiral.

This brings to mind an article from Nature from a couple of years ago that argued that fertility follows a “J” curve with respect to human development. The graph plots fertility against human development (HDI) by country in two time periods:

That is, rather than fertility declining irreversibly with higher levels of development (which is what one might have thought in 1975, or in Russia through the 1990s); it appears that fertility seems to recover a bit at the highest levels of development. This doesn’t apply to all countries — Japan and Italy may have been left behind — but partially explains the relatively high fertility rate of, say, native-born Americans. Explaining the drop in fertility with rising development is easy; explaining the subsequent rise is a little tougher. I see two basic options:

1) It’s important that the measure here is HDI, as opposed to GDP/capital. What’s crucial is the level of female empowerment. Where women have the option to work and raise children, they frequently do so. Where they cannot as easily (Germany for instance, where a substantial cohort of women remain childless and attached to the workforce), women are simply forced to choose. It’s no coincidence that countries like Japan or Italy see plummeting fertility even at high levels of income.

2) This represents the optimal parenting strategy across income ranges. At Malthusian levels of income, additional income is spent on more children. As incomes rise, families start to face a “quantity/quality” tradeoff that leads to them invest more in fewer children. At yet higher levels of income, families are able to invest fully in multiple children.

It’ll be worth seeing whether some of the low-fertility countries out there today — particularly in Southern/Eastern Europe and Eastern Asia — recover. At some point, many countries will also start maxing out their HDI, and we’ll need another indicator. Perhaps people are reading Selfish Reasons to Have Children.

11 Comments

  1. A large population shouldn’t have a mutational-meltdown type spiral. The fraction with more pro-natal personalities or subcultures should grown in proportion of the population. I recall Discover GNXP having some good graphs making such a point with hypothetical populations, and I believe using Russia as a starting point.
    Yes, here we go:
    http://blogs.discovermagazine.com/gnxp/2010/10/the-wheel-of-history-turns-to-the-gods/

  2. Exactly. Where is the genetic hypothesis here on GNXP?

    Evolution neednt be slow. If the black death kills everyone with the wrong genotype, gene frequencies can completely flip within a generation.

    If birth control kills everyone without a psychological drive to reproduce…

    ‘sex drive’ is just a completely obsolete mechanism in todays world; but something will take its place, and it will do so in centuries or even decades, not eons.

  3. As I’ve mentioned before, there is a problem in the way TFRs are calculated. If women are delaying having babies – say, having them in their 30s rather than their 20s – there will be a transitional period during which TFRs will underestimate completed birth numbers. Eventually (assuming that the new fertility pattern is permanent) the TFRs will catch up, and appear to increase. So at least part of this increase is likely to be spurious.

  4. > That is, rather than fertility declining irreversibly with higher levels of development (which is what one might have thought in 1975, or in Russia through the 1990s)

    Russia in 1990s is certainly not a good example of increasing level of development, just the opposite. This, of course, does not invalidate the rest of your article.

  5. The scatter in the diagram does not really support a J-shape. It looks more like a flat minimum extending from about HDI 0.8 to the right.

    This is an example of using a line to impose meaning and pattern on a scatter plot that has none.

  6. I believe that the demographer/economic historian Richard Easterlin was making claims like this in the 1970s.

  7. For an elaboration on DavidB’s point, see my old posts here and here, which describe a model wherein delaying childbirth can temporarily depress the measured fertility rate even if the number of children each woman has over the course of her life is held constant.

  8. Non ethnic Russian immigrants into Russia have higher birthrates than ethnic Russians. But their priorities and aptitudes are not necessarily lined up with those of most ethnic Russians. This is a case where “recovery of TFR” may not be the same as recovery of the nation.

  9. As an interesting aside there are projections that show that in one hundred years the majority of Americans will be Ana-baptists.

  10. This is more a question of psychology. Genetic only with regard to the correlation with higher IQ nations/people.

    In Germany the government has Kindergeld, ELterngeld,a former Baukindergeld (now incorporated into other programs), and many smaller programs. But they can’t get an increase in the rates of ethnic Germans (note: lower social economic Germans still have more kids than higher social economic Germans). They also have a healthy Hartz IV (welfare) for people. The problems in Germany and the rest of Europa are more to do with psychological issues which include economic perceptions.

    Far as these numbers coming up in the future… yes they will. This will happen when the native populations are replaced with a higher reproducing people. Currently 30 percent of Germans under 15 have an immigrations background. This doesn’t really reflect the coming of an increase in reproduction though as many of these are still from European populations.

    For some comparisons on population growth look at 1950s Africa which was estimated at near 230 million people. In 2010 just over 1 billion and in 2050 projected to be just shy of 2 billion. Europe in comparison was 1950: 547mil.; 2010 732 mil; and project for 691 mil in 2050.

    Survival of the fittest will replace the higher IQ populations for their lack of reproductive desires.

  11. It seems too that as populations change, homes become more affordable, and fertility might increase after a period of decline, rising and falling based on the economic and other incentives to have more or fewer children.

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