From grad student Kevin Bird:
SUBMITTED ON January 27, 2020
Protracted debates about the cause of an observed IQ gap between Black and white populations around the world have persisted within the fields of genetics, anthropology, and psychology for over a century. Newly available public genomic data have changed each of these fields in many ways; one side effect is that they have encouraged a new generation of race science. The current generation of race scientists claims that analysis of polygenic scores—generally computed as linear combinations of alleles identified by a genome-wide association study—provide evidence that a significant portion of differences in cognitive ability between Black and white people are caused by genetic differences, frequently claiming these differences came about due to divergent natural selection. In light of recent calls for cautious interpretation of polygenic-score analyses by geneticists, I apply the latest robust methods to detect genetic differentiation and polygenic selection that address known biases in polygenic-score analysis, testing the claim that genetic differences explains the gap in educational attainment and cognitive performance and that divergent selection has occurred between African and European populations. I show that past results were inflated by these biases and a more careful analysis provides strong evidence inconsistent with divergent selection and genetic differences driving the Black-white gap in cognitive ability.
I haven’t read this new paper so I don’t have an opinion on it. But, as I pointed out in 2002, because the immense IQ gap between European countries and sub-Saharan countries of about 30 points is about twice the IQ gap between white Americans and black Americans, that suggests a substantial amount of the European vs. SubSaharan gap is due to the harshness of the sub-Saharan environment.
As I wrote in VDARE.com in 2002 in my review of Lynn and Vanhanen’s book IQ and the Wealth of Nations:
… It appears likely that some combination of malnutrition, disease, inbreeding, lack of education, lack of mental stimulation, lack of familiarity with abstract reasoning and so forth can keep people from reaching their genetic potential for IQ. Lynn himself did early studies demonstrating that malnutrition drives down IQ. The co-authors conclude their book by recommending that
“The rich countries’ economic aid programs for the poor countries should be continued and some of these should be directed at attempting to increase the intelligence levels of the populations of the poorer countries by improvements in nutrition and the like.”
A clear example of how a bad environment can hurt IQ can be seen in the IQ scores for sub-Saharan African countries. They average only around 70. In contrast, African-Americans average about 85. It appears unlikely that African-Americans’ white admixture can account for most of this 15-point gap because they are only around 17%-18% white on average, according to the latest genetic research. (Thus African-Americans white genes probably couldn’t account for more than 3 points of the gap between African-Americans and African-Africans.) This suggests that the harshness of life in Africa might be cutting ten points or more off African IQ scores.
Similarly, West Africans are significantly shorter in height than their distant cousins in America, most likely due to malnutrition and infections. …
This also implies that African-Americans might be able to achieve higher IQs too, although the environmental gap between white Americans and black Americans appears to be much smaller than between black Americans and black Africans. …
In fact, we know that IQ is not completely fixed over time because raw test scores have been rising for decades, about 2 to 3 points per decade. …
While the causes of the Lynn-Flynn Effect remain rather mysterious, it does resemble several other ongoing phenomena. For example, human beings are getting taller, living longer, and having fewer of their babies die during infancy.
One might expect IQ scores to converge as the richest nations experience diminishing marginal returns on improvements in nutrition, health, and education. By way of analogy, consider how, after 1950, average height has not grown as fast in already well-fed America as it has in rapidly developing East Asia.
… Perhaps that kind of convergence will happen with IQ scores someday. But the evidence that it is happening now isn’t terribly strong. The odd thing about the Lynn-Flynn Effect is that it doesn’t seem to have had much impact on comparative rankings of IQ over time. The smart seem to keep on getting smarter.