Commenter Mug of Pee writes:

he rots in the [Northern] california coast.


he sears/is sere and dies in the Saguaro National Park.


so [an HBDer] walks through Redwood National Park. he looks around and sees no cacti. he concludes that cacti are genetically inferior to redwoods.

he walks through Saguaro National Park. he looks around and sees no redwoods. he concludes that redwoods are genetically inferior to cacti.

Mug of Pee has been preaching the gospel of reaction norms for years and insisting that HBDers don’t grasp the concept.  I think I do, though I never heard of it until Mug of Pee mentioned it.  It was not discussed in any HBD book I read (though I’ve only read a few authors).

The Phenotype = Genotype + Environment model (independent genetic effects)

Of course I was well aware that environment affects IQ (the Flynn effect is proof of that), but my thinking was confined to the Phenotype = Genotype + Environment model which states that while the same genotype can have a very different phenotype depending on which environment it’s reared in,  the rank order of phenotypes will remain very constant regardless of which environment the genotypes are reared in, as long as they’re reared in the same one.

So for example, although environment drastically affects the heights of men and women (both sexes are much taller today than in the 19th century, and both sexes are much taller in the developed World than in the Third World) the male > female height gap remains of similar size and direction across time and place.

Reaction norm model (dependent genetic effects)

The reaction norms model is more subtle, instead arguing that genes for tallness in environment A might be genes for shortness in environment B, so while men might be taller than women in America, if those same genotypes were raised in a different country, the women might be taller than the men.

Of course in reality we don’t see this.  Men are taller than women on average in every country and time period I’m aware of, thus the sex-linked height genes would be what Mug of Pee calls “independent genetic effects”, meaning their effect on the phenotype is independent of the environment (the Phenotype = Genotype + Environment model) because no matter what environment you’re in, having a Y chromosome adds height.

You’ll be much taller if raised in 21st century Western Europe than in 19th century sub-Saharan Africa, but in both times and places, you’ll be much taller with a Y chromosome than without.  Mug of Pee concedes that physical genotypes (i.e. height genes) tend to have independent genetic effects, however he suspects that mental genotypes (IQ genes, personality genes, genes for autism and schizophrenia) have dependent genetic effects because humans are cultural creatures known for our behavioral plasticity.

Mug of Pee feels that most estimates of the heritability of IQ (whether from twin studies of Genome-wide Complex Trait Analysis) are too high because they are limited to people in the same country, and it could be that a certain genotype increases IQ all over that country, thus spuriously increasing heritability, when in another country it may decrease IQ.  To get a better estimate of heritability, Mug of Pee would like to see a study where identical twins reared apart were not just raised in different towns, but different developed countries (i.e. an American’s identical twin is raised in Japan, a Canadian’s identical twin is raised in Germany).  If this were done, Mug of Pee feels the adult IQ correlation of identical twins raised apart would drop precipitously because a genotype that intellectually benefits from one country’s language or education system might be stunted by another’s.

In support for the reaction norm model of IQ, Mug of Pee frequently cites Ashkenazi Jews who were intellectually super accomplished in the 20th century, but barely a blip on the radar screen in prior centuries.

Ability vs. success

The problem with thinking IQ follows a reaction norm model is that IQ is moderately correlated with physical traits like brain size and highly correlated with physiological abilities like the speed and consistency of complex reaction times and physical genotypes seem to have independent genetic effects.

However Mug of Pee might be half-right.  While IQ genes probably have independent genetic effects, success genes (i.e. wealth, status, power, eminence) probably follow the reaction norm model to a large degree.  So while Ashkenazi Jews may have had higher IQs than gentiles for many centuries, their achievements only surpassed those of Gentiles in the 20th century because the cultural and economic changes that occurred were both favorable to the Ashkenazi genotype and unfavourable to the Gentile genotype.

So wealth, status, and achievement genotypes may have environment dependent effects.  Billionaire Warren Buffet has stated that his brain is just wired for a certain type of thinking that happens to be valued in modern markets, but in other periods of history he would have been a loser.  So while Warren’s mathematical genotype is an independent genetic effect, his wealth genotype may be a dependent genetic effect.  Bill Maher has stated that he’s only rich because it’s a fluke to live in a society where you gain wealth by telling jokes.

So one can see how a reaction norm view of humanity would correlate with Marxism and commenter Mug of Pee is a devout Marxist.

I suspect the heritability of income, power, and status would drop much more when moving from a within country twin study to an international twin study, than the heritability of IQ would because I suspect achievement is much more culture dependent than IQ.  Nonetheless, I feel even the former variables are caused by some independent genetic effects.