Looking beyond the data

 

General intelligence (g factor) as a function of alleles associated with educational attainment (Education polygenic score). (Fuerst et al. 2021, p. 165)

Among non-Hispanic European Americans, cognitive ability shows a positive correlation with Amerindian admixture. The reason is to be found in the history of European settlement.

 

 

We know that cognitive ability differs among human populations, but are those differences innate? Or are they purely cultural? The question is difficult to answer because a purely cultural difference can, over time, become innate. If you are better able to meet the demands of your culture, you will probably live longer, have more offspring, and pass on many of your characteristics. Thus, over succeeding generations, those heritable characteristics will become more and more widespread in the gene pool, and they will increasingly determine certain abilities that were initially created by culture.

 

This is a recurring problem when we try to distinguish between cultural and genetic determination. The two often run parallel to each other, and we can seemingly rule out the existence of genetic determination by showing that cultural determination runs in the same direction.

 

But there is another recurring problem in our efforts to distinguish between culture and genetics. We lack the proper tools. For a long time, we could only infer genetic influences by using twin studies or adoption studies. 

 

Things have changed with the advent of a new tool: genomic data. Specifically, we can now:

 

·         Measure ethnic ancestry in mixed populations, as opposed to using self-report or inferring from skin color.

·         Measure the genetic component of cognitive ability, by using genetic variants associated with educational attainment. Although these variants explain only 11-13% of the variance in educational attainment among individuals, they explain a much higher percentage of the variance among populations (Piffer 2019). This is because genetic variants within the same population are exposed to the same pressure of selection and will thus vary in the same direction. They act, so to speak, as “weathervanes” that tell us the strength and direction of selection in that population.

·         Measure skin color, by looking at the relevant genes. We can thus control for the effects of “colorism” in mixed populations, i.e., discrimination in favor of lighter-skinned individuals.

 

In my last post, I described how Bryan Pesta used these tools to understand differences in mean cognitive ability between African Americans and European Americans (Lasker et al. 2019). To that end, his research team looked at cognitive ability among African Americans in relation to European admixture and in relation to genetic variants associated with educational attainment.

 

They made several findings: 1) among African Americans, cognitive ability correlates with European admixture; 2) the correlation is modestly reduced, but not eliminated, when controlled for parental education; 3) controlling for skin color has no effect; and 4) the correlation seems to be largely explained by genetic variants associated with educational attainment.

 

The same data source was then used by Fuerst et al. (2021) to investigate cognitive ability not only in European Americans and African Americans but also in Hispanic Americans. The research team thus looked at cognitive ability in relation to Amerindian admixture, and not just in relation to European and African admixture.

 

Most of their findings are similar to those of the first study:

 

·         Among Hispanic Americans, cognitive ability shows a positive correlation with European admixture and a negative correlation with African admixture and Amerindian admixture.

·         Among Hispanic Americans, the correlations are reduced but not eliminated by controlling for parental education. Controlling for skin color has no effect.

·         The above correlations are partially explained by variants associated with educational attainment, but not by skin color.

·         Among non-Hispanic European Americans, cognitive ability shows a positive correlation with Amerindian admixture.

 

The last correlation may seem curious. Keep in mind that the data came from residents of Pittsburgh and that the native peoples of the Eastern U.S. intermixed mostly with early settlers of British, Dutch, or French origin. There is much less Amerindian admixture among the descendants of later immigrants from southern and eastern Europe. The correlation may thus be due not to Amerindian admixture per se but rather to variation in cognitive ability among Europeans.

 

Until the eleventh century, mean IQ was relatively low throughout Europe, perhaps hovering in the low 90s. It then rose during late medieval and post-medieval times through the expansion of the middle class. There was in fact a broad mental and behavioral change: "Thrift, prudence, negotiation, and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent, and leisure loving" (Clark 2007, p. 166; see also Clark 2007, 2009a, 2009b). More people could better understand probability, cause and effect, and another person’s perspective, whether real or hypothetical (Rinderman 2018, pp. 49, 86-87; Oesterdiekhoff 2012). As the "smart fraction" grew in size, a point was reached when intellectuals were no longer voices crying in the wilderness. They were now numerous enough to form learned societies and collaborate in projects of various sorts (Frost 2019b, pp. 175-176).

 

Western Europe was where the middle class began to expand, and that was where the expansion would have its greatest impact, not only demographically but also behaviorally and cognitively. Gregory Clark (2009a) has shown that the English, even in the lower classes, are largely descended from people who were middle-class several generations earlier. The same is likely true elsewhere in Western Europe. We should therefore see a cognitive gradient between the Western European core and its periphery, as can indeed be seen between northern and southern Italy. When Piffer and Lynn (2022) looked at genomic data from that country, they found a north-south gradient in alleles associated with educational attainment. That difference corresponds to historical differences in economic development. By the 18th century, the South had already fallen behind the North; its middle class had remained small and economic relations were still structured by paternalism and familialism (De Rosa 1979).

 

All of that leads to an interesting corollary: the IQ gap used to be smaller between Europeans and sub-Saharan Africans. On the one hand, European mean IQ had probably remained in the low 90s until late medieval times. On the other hand, mean IQ may have been in the upper 80s among those Black African groups that Europeans had first encountered, particularly the Nubians. By the time of Classical Antiquity they had reached a high level of material culture, social complexity and State formation.

 

A smaller IQ gap would be in line with an observation by Jason Malloy. He noted that blacks were often described in the ancient world as having large penises but not as being less intelligent. Indeed, I have found only two Greco-Roman texts in which the writer disparaged Black Africans as being unintelligent. One of them is of doubtful authenticity, and both come from Late Antiquity (Frost 2019b). By then, blacks in the Roman world were increasingly slaves who came from farther within the African interior. Thereafter, a stereotype of low intelligence is regularly attested in Middle Eastern and European sources.

 

 

References

 

Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World. Princeton University Press: Princeton and Oxford.

 

Clark, G. (2009a). The indicted and the wealthy: surnames, reproductive success, genetic selection and social class in pre-industrial England.  http://www.econ.ucdavis.edu/faculty/gclark/Farewell%20to%20Alms/Clark%20-Surnames.pdf     

 

Clark, G. (2009b). The domestication of man: The social implications of Darwin. ArtefaCTos 2: 64-80. https://www.researchgate.net/publication/277275046_The_Domestication_of_Man_The_Social_Implications_of_Darwin

 

De Rosa, L. (1979). Property Rights, Institutional Change, and Economic Growth in Southern Italy in the XVIIIth and XIXth Centuries. Journal of European Economic History 8(3): 531-551.

 

Frost, P. (2019a). The Original Industrial Revolution. Did Cold Winters Select for Cognitive Ability? Psych 1(1): 166-181. https://doi.org/10.3390/psych1010012   

 

Frost, P. (2019b). Why that stereotype and not the other? Evo and Proud, July 28. https://evoandproud.blogspot.com/2019/07/why-that-stereotype-and-not-other.html

 

Frost, P. (2021). Commentary on Fuerst et al: Do Human Populations Differ in Their Mental Characteristics? Mankind Quarterly 62(2). http://doi.org/10.46469/mq.2021.62.2.9   

 

Fuerst, J., E.O.W. Kirkegaard and D. Piffer. (2021). More research needed: There is a robust causal vs. confounding problem for intelligence-associated polygenic scores in context to admixed American populations. Mankind Quarterly 62(1): 151-185. https://www.researchgate.net/profile/John-Fuerst/publication/354767141_More_Research_Needed_There_is_a_Robust_Causal_vs_Confounding_Problem_for_Intelligence-associated_Polygenic_Scores_in_Context_to_Admixed_American_Populations/links/614bc1dfa595d06017e4c017/More-Research-Needed-There-is-a-Robust-Causal-vs-Confounding-Problem-for-Intelligence-associated-Polygenic-Scores-in-Context-to-Admixed-American-Populations.pdf

 

Lasker, J., B.J. Pesta, J.G.R. Fuerst, and E.O.W. Kirkegaard. (2019). Global Ancestry and Cognitive Ability. Psych 1(1):431-459. https://doi.org/10.3390/psych1010034  

 

Oesterdiekhoff, G.W. (2012). Was pre-modern man a child? The quintessence of the psychometric and developmental approaches. Intelligence 40, 470–478. https://doi.org/10.1016/j.intell.2012.05.005

 

Piffer, D. (2019). Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from Gwas Hits: A Replication of Previous Findings Using Recent Data. Psych 1(1):55-75. https://doi.org/10.3390/psych1010005

 

Piffer, D., and R. Lynn. (2022). In Italy, North-South Differences in Student Performance Are Mirrored by Differences in Polygenic Scores for Educational Attainment. Mankind Quarterly 62(4), Article 2. https://doi.org/10.46469/mq.2022.62.4.2   

 

Rindermann, H. (2018). Cognitive Capitalism. Human Capital and the Wellbeing of Nations, 1st ed.; Cambridge University Press.