Thread by @PaoloShirasi

[THREAD]

A VERY BASIC INTRODUCTION TO THE HEREDITARIAN POSITION ON RACE AND IQ.

PART 13: The Hereditarian Explanation –- Admixture Studies

So far I've talked about how the overwhelmingly genetic basis of individual differences in IQ, along with findings from transracial adoption studies, brain studies and population genetics, tend to support a hereditarian (genetic) explanation for the IQ gaps between races.

In this thread, I'll discuss yet another argument used by hereditarians: Racial admixture studies which show that mixed-race populations (i.e., children of one black and one white parent) have, on average, IQs between the averages of white and black populations.

You'll remember from the previous thread on transracial adoption studies how mixed-race children adopted into upper middle-class white families fare better on average than the black adoptees, but worse on average than the white adoptees on IQ test performance.

A well-known example of an equidistant racial admixture study conducted in South Africa found that the average IQ of the mixed-race population averaged about 85, perfectly intermediate to the black average of 70 and the white average of 100.

Side Note: You'll notice the low black South African IQ. Hereditarians argue that US blacks have a higher average IQ than sub-Saharan Africans at least partly because of their racial admixture (about one-quarter of the gene pool of African-Americans is European).

“Data from large, publicly available, archival data sets... show that groups of mixed-race individuals have mean scores intermediate to unmixed groups of Blacks and of Whites,” according to a 2002 study.

Relatedly, the wide range of average IQs among South American nations also provides some insight into racial admixture.

As one would expect under the hereditarian hypothesis, those nations comprised of mostly-white admixture (e.g., Argentina, Chile) have higher average IQ scores than those comprised of mostly-non-white admixture and population (e.g., Bolivia, Ecuador).

Another interesting finding from admixture research is that “[c]hildren wrongly believed by adoptive parents to have had two black biological parents [they actually had mixed black-white parentage] had the same IQs as children correctly classified as of mixed race.”

A 1961 admixture study finding that out-of-wedlock mixed-race children of African-American GIs and German women had the same IQ as out-of-wedlock children produced by white American GIs and German women is often cited by environmentalists.

However, this study is severely flawed for several reasons:

First, the children were very young, tested before puberty, mostly before the full “Wilson Effect”; second, a quarter of the “black” fathers were actually North Africans (not sub-Saharan African); and...

...third (and most importantly), the black GIs were unrepresentative of the average African-American due to “rigorous pre-induction selection” by the US Army which was based upon — you guessed it — the results of intelligence testing.

This testing (i.e., the Army General Classification Test) removed the lowest-scoring blacks for selection into the service (about one-third of all blacks taking the test). Only about 3% of whites were removed. This had an obvious equalizing effect.

Finally, while GWAS investigation into admixture and IQ is just beginning, a decent-sized 2019 study involving an admixture analysis found that “European ancestry was a consistent predictor of cognitive ability,“ consistent with the findings discussed above.

The study's bottom line interpretation of the findings supports an estimate of roughly 60% of the black-white gap being genetic, which is what some hereditarians have long suspected it to be.

SOURCES:

cambridge.org/core/books/han…

www1.udel.edu/educ/gottfreds…

Eyferth, K. (1961). Leistungen verschiedener Gruppen von Besatzungskindern in Hamburg-Wechsler Intelligenztest für Kinder (HAWIK). Archiv für die gesamte Psychologie, 113, 224-241.

mdpi.com/2624-8611/1/1/…