In the comments section, there is a discussion going on about when IQ stabilizes in humans.
David: I may be wrong, but I think that IQ scoring as early as the age of 5 or 6 remains fairly constant over the duration of an individual’s lifetime.Robert Lindsay: For non-Blacks, it’s pretty stable from age 7. For US and UK Blacks, it declines from age 5 until age 18-24, then it levels off. We don’t understand what’s going on.
David: That seems kind of weird biologically speaking. Maybe there is some sort of massive underclass cultural dumbing-down effect at work here?
This is truly a bizarre phenomenon. Young Black kids are quite intelligent. I babysat for some young Black boys recently for an hour so, and I did not get the impression that they were stupid at all. In fact, I thought they were smarter than their mother! Their minds were working very quickly, almost like little pinball machines. If their IQ’s were average, then they were around 93-95. That’s not a low IQ at all.
I suspect it is only occurring in the West, but I can’t prove it. I know it is happening in both the US and the UK. The Black IQ starts to decline at age 5 and continues crashing down about 10 points all the way to 18-24, when it levels off for the rest of life. Young Black kids are not dumb at all, so there seems no justification for them to do poorly in school or screw off a lot. Whatever is going on, it cannot be related to IQ. I believe that Black and White scores in school start diverging quite a bit around 5th grade or age 10.
There are different ways to look at this data.
James Flynn says he knows of no genetic reason why Black IQ’s would decline from age 5 to age 21. In fact, I do not believe that they do so in Africa, so it’s not genetic, and you wonder why genetics would select for something so weird anyway.
The explanation here is that Black culture dumbs down Blacks intellectually, and this is why they fall as they move though childhood and young adulthood. It’s an interesting theory, but it’s not proven yet.
The hereditarian response is much more frightening, and I hope it is not true. They say that the IQ’s of Blacks in the US and UK are being artificially heightened beyond their genetic set by the massively intellectually complex culture of the US and the UK. However, this effect is most pronounced in childhood, when environmental effects hit hardest, and declines as one hits adulthood, when genetic effects tend to predominate and environmental effects wear off. Anyway, this is not proven yet either.
Even adult Black IQ seems to be possibly being artificially stimulated by the intellectually complex culture of the modern West. Logically speaking, on a pure hereditarian basis, the Black IQ in the US and UK should be 72.5 in the US and 71 in the UK. Instead, it is 87.8 in the US and 86 in the UK. There is a gain of 15.3 points in the US and 15 points in the UK that seems to be completely unaccountable for by a hereditarian perspective. I suggest that that 15 point boost may be due to the heightened environment in the West, including diet.
Nevertheless, the 10 point drop in Black Western IQ remains unexplained and perplexing. Any theoretical comments on this mysterious matter are welcome.