Now that we have established that immigration is not much good, let’s take a look at another component undergirding our transition to Idiocracy – the differential fertility rates of different IQ groups.
This is a highly contentious topic, and not just on account of the usual political kurfuffles, but also on real disagreements as to its actual extent. Psychologists such as Richard Lynn, Edward Dutton, and Michael Woodley are pessimistic (Woodley 2014; Dutton et al. 2016). OTOH, JayMan has argued based on WORDSUM analysis that “Idiocracy can Wait.” This topic is extra difficult because you also have to disentangle the dysgenics trend from the Flynn effect that has raised IQs in the developed by about 10 points during the 20th century.
The PISA Data Explorer is truly an invaluable tool for bringing the light of cold, hard facts on these issues.
While playing around with it, I noticed you can select the variable “same age siblings,” which ranges from zero to ten. Zero siblings implies, of course, that the student in question is an only child; by definition, the survey excludes entirely the childless portion of the population, which is also its brightest. Data only exists for the Mathematics part of PISA 2000, but it is more than enough to get an idea of the general trend – and as you might expect, it’s not a very good one.
I calculated the “slope” in terms of PISA-adjusted IQ points lost per additional sibling for the first four siblings (in practice, since TFR <<6 for all countries in PISA 2000, the IQ of children from even larger families won’t have much of an effect). See the table at the bottom of this post.
(1) Indonesia is the only country, at least as judged from the Math portion of PISA 2000, that has eugenic fertility patterns (since its a developing country with a TFR = c.2.5, we can be pretty sure that childlessness will not impact these statistics down by very much since its simply very rare). Second is Thailand. Both are lower-middle income Asian countries that only escaped the Malthusian trap within living memory and are in the middle stages of the demographic transition. (That said, in PISA 2015, coverage of the 15 year old population was not great in either country – 68% in Indonesia, 71% in Thailand – and assuming that was also generally true in 2000, those not turning up are sure to be less bright and will probably come from more rural, bigger families).
[Epistemic status: Speculative]. However, despite also being within the middle-income brackets, the Latin American countries have moderately dysgenic fertility patterns. I wonder if this could explain Steve Sailer’s observation that Latin American countries seem to have smaller smart fractions than Middle Eastern ones, despite similar average IQs. Maybe their European and, critically, Europeanized, upper classes have simply failed to reproduce in the last couple of generations?
(2) The East Asian and European Nordic states have more eugenic fertility patterns. The European Mediterranean – Greece, Italy, Romania, Portugal, Bulgaria – has some of the worst. France, Spain, Brazil, the UK, Germany, Poland, Russia, and the US all cluster close to each other (though American White fertility is probably more eugenic, perhaps around Australia’s and Canada’s level, since minority and especially Black fertility patterns are known to be highly dysgenic even according to JayMan’s optimistic analysis).
(3) The rate of childlessness is considerably lower, at around 10%, in the ex-Soviet bloc and East-Central Europe than in Western Europe and the US.
That data does exist, at least for many of the OECD countries and Russia, so its doable, but it would be a pretty big project.
(5) Eyeballing it there seems to be a moderate degree of correlation with commenter Cicerone’s country estimates of dysgenic fertility extracted from fertility data of educational classes.
IQ vs. #Siblings