My wish list for research in 2024: Recent cognitive evolution in West Africa

 

Drainage basin of the Niger River (Wikicommons - Wizardist)

Social complexity was more advanced, and cognitive demands higher, in West African societies that benefited from trade via the Niger River. This was especially true for the Igbo of the Niger Delta, who dominated trade between the coast and the interior.

 

We have identified thousands of genes whose alleles are associated with cognitive ability, i.e., the capacity to process information, to recognize patterns, and to solve problems (Lee et al., 2018). By finding out which alleles are present on an individual’s genome, we can make an estimate of that person’s cognitive ability, and that estimate will show a high correlation with performance on tests in mathematics, reading, and science (r = 0.8). The same method can provide an estimate of a population’s mean cognitive ability, and that estimate will show a high correlation with the population’s mean IQ (r = 0.9) (Piffer, 2019).

 

Using this method, the anthropologist Davide Piffer has estimated the mean cognitive ability of several West African populations. Mean cognitive ability seems to increase as you go from west to east, being lowest among the Mende of Sierra Leone and progressively higher among Gambians, the Esan of Nigeria, and the Yoruba of Nigeria. The Yoruba have almost the same mean as do African Americans, who are nonetheless 20% European by ancestry (Piffer, 2021, see Figure 7).

 

This geographic pattern seems to reflect differences in societal development. From the fourth century onward, West African societies became more complex in the north and the east, i.e., within the drainage basin of the Niger. As trade along that river increased in volume and value, villages grew into towns, and social relations became more varied and complex. This social complexity was both a cause and effect of trade. As powerful individuals acquired the materials they needed to erect buildings, create works of art, and hold ceremonies to legitimize their rule, they became even more powerful and, thus, better able to purchase such materials. Social complexity was thus driven by a positive feedback loop: elite buying power led to an increase in trade, which in turn led to an increase in elite buying power (Frost, 2022; McIntosh and McIntosh, 1988, p. 123).

 

As social relations became more varied and complex in settlements along the Niger, those populations had to cope with a heavier cognitive workload. The demands of farming were giving way to those of craft production, urban architecture, and long-distance trade. Numeracy and literacy were becoming important, as were skills for manipulation and assemblage of various materials. Did that new social environment select for an increase in cognitive ability?

Evidence of high cognitive ability is especially strong among the Igbo people (formerly the Ibo), who live at the Niger’s mouth and who have historically dominated trade between the coast and the interior (Frost, 2022). Their children excel at school not only in Nigeria but also in overseas communities, such as those of the United Kingdom. They do exceptionally well on the GCSE (Chisala, 2015).

 

In addition to high cognitive ability, the Igbo are said to have a certain mindset: “the Ibo have a greater achievement motivation and are more willing to explore new avenues of power than either the Yoruba or the Hausa.” They have “a general belief in the possibility, indeed necessity, of manipulating one’s world; of determining one’s own destiny; of ‘getting up’ in the world” (Slater, 1983).  The earliest European observers, from the eighteenth century, described them as “competitive, individualistic, status-conscious, antiauthoritarian, pragmatic, and practical—a people with a strongly developed commercial sense” (Mullin, 1994, p. 286).

 

Trade thus seems to select for higher cognitive ability, either directly through new cognitive demands (i.e., pricing, bargaining, accounting) or indirectly through a resulting increase in social complexity. This has been the case not only among the Igbo but also among the Ashkenazi Jews, the Parsis, and other trading peoples (Cochran et al., 2006; Frost, 2012; Frost, 2021). As these peoples became specialized in trade, over the past millennium or so, they appear to have experienced a sharp rise in mean cognitive ability. These examples of recent evolutionary change support the view that mental and behavioral evolution did not stop back in the Pleistocene, anymore than the evolution of outward physical traits like skin color or body shape. Cognitive ability continued to evolve into the time of recorded history, albeit to different extents in different human groups (Cochran and Harpending, 2009; Hawks et al., 2007; Rinaldi, 2017).

 

Shell vessel with leopard from Igbo-Ukwu, Nigeria, ninth century (Wikicommons). This bronze artefact, like others from the same site, has an unusually high silver content with only traces of zinc, an alloy not used in Europe or the Middle East at that time. Ancestral Igbo thus seem to have developed metallurgy on their own (McIntosh and McIntosh, 1988, pp. 120-121).

 

Proposed study

 

The aim is to test the hypothesis that mean cognitive ability increased to a greater extent in those populations that were closer to the Niger, particularly the Igbo at the Niger’s mouth, where trade led to greater social complexity and higher cognitive demands during precolonial times.

 

For this study, mean cognitive ability can be estimated from genomic data, specifically from alleles associated with educational attainment (Edu PGS). The alleles identified to date are only a fraction of all those that play a role in cognitive ability, but we have identified enough of them to produce reliable estimates of mean cognitive ability within a population. With the help of data from history and prehistory, we could then outline the trajectories that mean cognitive ability has followed in different West African populations.

 

Finally, these hypothetical trajectories could be verified by retrieving and examining aDNA from archaeological sites throughout West Africa. It would be particularly interesting to determine when mean cognitive ability began to increase among ancestral Igbo, and how fast it increased. That research aim may be unrealistic, however, given the degradation of DNA in hot climates.

 

References

 

Chisala, C. (2015). The IQ gap is no longer a black and white issue. The Unz Review, June 25. http://www.unz.com/article/the-iq-gap-is-no-longer-a-black-and-white-issue/

 

Cochran, G., J. Hardy, and H. Harpending. (2006). Natural history of Ashkenazi intelligence. Journal of Biosocial Science 38(5): 659-693. https://doi.org/10.1017/S0021932005027069

 

Cochran, G. and H. Harpending. (2009). The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. Basic Books: New York.

 

Frost, P. (2012). Tay-Sachs and French Canadians: A case of gene-culture co-evolution? Advances in Anthropology 2(3): 132-138. http://dx.doi.org/10.4236/aa.2012.23016     

 

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

 

Frost, P. (2022). West Africa and recent cognitive evolution. Peter Frost’s Newsletter, November 14. https://peterfrost.substack.com/p/west-africa-and-recent-cognitive   

 

Hawks, J., E.T. Wang, G.M. Cochran, H.C. Harpending, and R.K. Moyzis. (2007). Recent acceleration of human adaptive evolution. Proceedings of the National Academy of Sciences (USA) 104: 20753-20758. https://doi.org/10.1073/pnas.0707650104

 

Lee, J. J., R. Wedow, A. Okbay, E. Kong, O. Maghzian, M. Zacher, et al. (2018). Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals. Nature Genetics 50(8): 1112-1121. https://doi.org/10.1038/s41588-018-0147-3    

 

McIntosh, S.K., and R.J. McIntosh. (1988). From stone to metal: New perspectives on the later prehistory of West Africa. Journal of World Prehistory 2(1): 89-133. https://doi.org/10.1007/BF00975123    

 

Mullin, M. (1994). Africa in America: Slave Acculturation and Resistance in the American South and the British Caribbean, 1736-1831. University of Illinois Press.

 

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: 55-75. https://doi.org/10.3390/psych1010005

 

Piffer, D. (2021). Divergent selection on height and cognitive ability: evidence from Fst and polygenic scores. OpenPsych. April 3 https://doi.org/10.26775/OP.2021.04.03   

 

Rinaldi, A. (2017). We're on a road to nowhere. Culture and adaptation to the environment are driving human evolution, but the destination of this journey is unpredictable. EMBO reports 18: 2094-2100. https://doi.org/10.15252/embr.201745399   

 

Slater, R. (1983). Bureaucracy, Education and the Ibo: A Review. Journal of Educational Administration and History 15(1): 46-49. https://doi.org/10.1080/0022062830150106    

 

Cognitive evolution on the Italian Peninsula

 

A recent polygenic study has shown that mean cognitive ability is higher in the North of Italy than in the South. Cognitive evolution seems to have gone the farthest in the Northeast, perhaps because the Northwest earlier went through the Industrial Revolution, which severed reproductive success from economic success.

 

 

 

As a country, Italy came into existence only a century and a half ago. Regional differences are still strong, particularly between the North and the South. The “Southern question” is usually said to date from the unification of Italy in the 19th century:

 

In the decades following the unification of Italy, the northern regions of the country, Lombardy, Piedmont and Liguria in particular, began a process of industrialization and economic development while the southern regions remained behind. At the time of the unification of the country, there was a shortage of entrepreneurs in the south, with landowners who were often absent from their farms as they lived permanently in the city, leaving the management of their funds to managers, who were not encouraged by the owners to make the agricultural estates to the maximum. Landowners invested not in agricultural equipment, but in such things as low-risk state bonds. (Wikipedia 2022a)

 

De Rosa (1979) argues that the South had already fallen behind the North by the 18th century. At that time, its middle class was small, and economic relations were still structured by paternalism and familialism. One could go back even farther, to the Renaissance or even the late Middle Ages, to identify the moment when northern Italy, and Western Europe in general, embarked on sustained economic growth and thus pulled ahead of the rest of the world.

 

That sustained economic growth brought sustained demographic growth, particularly of the middle class. Gregory Clark found that the English middle class expanded steadily from the twelfth century onward, its descendants not only growing in number but also replacing the lower classes through downward mobility. By the 1800s, its lineages accounted for most of the English population. That demographic change coincided with mental and behavioral changes: higher cognitive ability, lower time preference, and a lower threshold for violent behavior. In a word, the English became more middle-class in character. “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).

 

Elsewhere in Western Europe, the middle class similarly expanded during late medieval and early modern times. The result would be a growing contrast between regions that had participated in this economic and demographic change and those that had not, such as southern Italy. The contrast can be seen not only on purely economic measures but also on mental ones, like the INVALSI standardized test—an annual test of skills in Italian schools. It is divided into two sections: Italian language skills and Math skills. On both tests, northern Italian students do better than southern Italian students, the difference being a little over half a standard deviation:

 

Yes, the North-South gap in academic achievement could have a purely environmental cause—and this is a recurring problem when we try to tease apart genetic and cultural evolution. If economic development is held back by a culture of poverty, that same culture may discourage students from trying to do better at school. Those students may also have less access to proper nutrition, medical care, libraries, and so on.

 

Polygenic scores for cognitive ability

 

That is why there is so much interest in measures of innate cognitive ability. The most promising one is the polygenic score (PGS)—the summation of alleles (genetic variants) that have been associated with cognitive ability, as measured by educational attainment.  At present, we have identified enough of these alleles to explain 11-13% of the overall variation in cognitive ability (Lee et al. 2018).

 

Yes, those alleles are just a sample of the total number, but why would they be an unrepresentative sample? More to the point: why would PGS data show certain geographic patterns and not a lot of random noise? The mean PGS does indeed differ geographically among human populations. It is highest in Eurasia, with East Asians, Ashkenazi Jews, and Finns having the highest scores. That geographic pattern is in line with IQ data (Piffer 2019).

 

Polygenic scores on the Italian Peninsula

 

In a recent study, Piffer and Lynn (2022) have found regional differences in Italy for alleles associated with educational attainment. They used two datasets: one encompassing 129 Italian individuals and the other 947. All of these individuals had all four grandparents born in the same part of Italy (this requirement was imposed to eliminate the effects of recent interregional migration). When the authors grouped the data into three large regions—North, Central, and South—they found “a clear north-south gradient, with central Italians occupying an intermediate position.” There was more overlap between central and southern Italians than between central and northern Italians.

 

The datasets were too small to show genetic differences within each of the three large regions. If we go back to the INVALSI data, we see that academic achievement is much stronger in the North-Northeast (Lombardia, Trentino, Veneto, Friuli) than in the Northwest (Valle d’Aosta, Liguria).

 

At first thought, that geographic pattern may seem counter-intuitive. In northern Italy, industrialization began in the northwest and came later to the northeast: “the diffusion of industrialisation that characterised the northwestern area of the country largely excluded Venetia and, especially, the South” (Wikipedia 2022b). If economic development had driven cognitive evolution on the Italian Peninsula, why would this evolution have gone farther in the northeast? Why would it be negatively associated with industrialization?

 

Because the Industrial Revolution put a stop to cognitive evolution. It severed the link between economic success and reproductive success. Previously, businesses were family-run, and the family provided the workforce. Successful business owners were incentivized to have larger families, and their children would have the means to marry at a younger age. Then, in the late 19th century, that stage of economic development began to give way to industrial capitalism. Financial success no longer translated into early marriage and large families who could help with the work. If more workers were needed, they would simply be hired. Business owners now tended to have smaller families because of the high maintenance costs of middle-class children (Canlorbe and Frost 2020; Frost 2018).

 

Cognitive evolution thus ended earlier in the Northwest of Italy than in the Northeast. By the same token, interregional migration has had more time to erode the cognitive advantage that evolved in the Northwest. Yes, the datasets were limited to people who had all four grandparents born in the region, but, for most people, that limitation would not eliminate the effects of interregional migration before the mid-20th century.

 

 

References

 

Canlorbe, G., and P. Frost (2020). Why are human groups so different? American Renaissance, March 20. https://www.amren.com/features/2020/03/why-are-human-groups-so-different/  

 

Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World, 1st ed. Princeton University Press: Princeton, NJ, USA.

 

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. (2018). Rise of the West. Part II. Evo and Proud, December 27

https://evoandproud.blogspot.com/2018/12/rise-of-west-part-ii.html  

 

Lee, J. J., Wedow, R., Okbay, A., Kong, E., Maghzian, O., Zacher, et al. (2018). Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals. Nature Genetics 50(8): 1112-1121. https://doi.org/10.1038/s41588-018-0147-3

 

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., & Lynn, R. (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  

 

Wikipedia (2022a). Economy of Italy – Southern Question

https://en.wikipedia.org/wiki/Economy_of_Italy#Southern_question  

 

Wikipedia (2022b). Economic history of Italy.

https://en.wikipedia.org/wiki/Economic_history_of_Italy  

 

John Fuerst's latest paper

 

The Igbo used their location on the Niger Delta to become traders between the coast and the interior. In the 18th century, they were already described as high achievers with a strong commercial sense. Cognitive ability seems to be higher in populations that specialize in trade, probably because the cognitive demands are likewise higher.

(Map of Niger - Wikicommons)

 

 

 

I was asked to comment on a recent study by John Fuerst, Emil Kirkegaard, and Davide Piffer. This study is well worth reading. It provides the strongest evidence to date for differences in mean cognitive ability between human populations, specifically by showing how cognitive ability correlates with alleles for educational attainment and with degree of European / African / Amerindian ancestry in European Americans, African Americans, and Hispanic Americans. Also worth reading is a related paper by John Fuerst, Meng Hu, and Gregory Connor.

 

The following is the abstract of my commentary:

 

Human populations may differ genetically not only in their anatomy but also in their mental characteristics. Our species is not too young for such differentiation. In fact, human genetic evolution has proceeded faster over the past 10,000 years than over the previous million. With the rise of farming, and social complexity, humans were no longer adapting solely to a limited range of natural environments. They were adapting to an ever-widening range of cultural environments, each of which imposed its demands on mind and body.

 

Thus, mental characteristics do not have the same adaptive value in all environments, and differences in adaptive value will lead, over time, to genetic differences. Are the latter large enough to explain IQ differences between human populations? That question has led to studies of people who are ancestrally diverse but raised in the same environment, such as transracial adoptees. Unfortunately, the environment can never be fully equalized. We should measure genetic differences directly, and a promising step in that direction has come with research to identify alleles associated with educational attainment. There is no need to identify all of them, just a large enough sample. These “witnesses” can then be questioned to determine the strength and direction of natural selection, and its consequences.

 

Also promising is the study of IQ and ancestry in ethnically mixed groups. This research instrument is not without problems. Large continental populations often have high-achieving minorities who may contribute disproportionately to the founding of new groups or to admixture with old ones. In addition, natural selection can alter the distribution of alleles within a new group, even after a few generations.

 

References

 

Frost, P. (2021). Commentary on Fuerst et al: Do Human Populations Differ in Their Mental Characteristics? Mankind Quarterly 62(2): 366-380.

http://doi.org/10.46469/mq.2021.62.2.9

https://www.academia.edu/73260728/Commentary_on_Fuerst_et_al_Do_Human_Populations_Differ_in_Their_Mental_Characteristics

 

Fuerst, J., Hu, M. & Connor, G. (2021). Genetic ancestry and general cognitive ability in a sample of American youths. Mankind Quarterly 62(1): 186-216.

https://www.researchgate.net/profile/John-Fuerst/publication/354766492_Genetic_Ancestry_and_General_Cognitive_Ability_in_a_Sample_of_American_Youths/links/614bbacaa595d06017e4bdbc/Genetic-Ancestry-and-General-Cognitive-Ability-in-a-Sample-of-American-Youths.pdf

 

Fuerst, J., Kirkegaard, E.O.W. and Piffer, D. (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  

Recent cognitive evolution in West Africa

 

If we look at alleles associated with higher educational attainment, we find more of them among the Yoruba of Nigeria than among the Mende of Sierra Leone. The reason may be differences in social evolution over the past 1,000 years, particularly in trade, urban settlement, State formation, and other forms of social complexity. 

Ife king's head (14th or early 15th century) (Wikicommons - Vassil)

 

 

How can we measure the genetic component of cognitive ability? We have long used IQ tests to get a rough idea, but they are not an ideal yardstick. Twin studies have shown that genetic factors explain about two thirds of the variance in IQ results, perhaps even less for comparisons between people of different cultural backgrounds.

 

In recent years we've found a new yardstick: the polygenic score. It's a more direct genetic measurement, being a summation of alleles that have been linked to higher educational attainment. As a method for estimating the mean cognitive ability of a population, it seems to be as good as IQ tests. Piffer (2019) found a 90% correlation between the two methods. In his latest study, he has again found the same correlation (Piffer 2021, see Figure 8).

 

Interestingly, that study shows differences in mean cognitive ability within West Africa: the Mende of Sierra Leone score much lower than the Yoruba of Nigeria. In fact, the Yoruba have almost the same polygenic score as do African Americans, even though the latter have about 20% European admixture. Unfortunately, we have no data on the Igbo of Nigeria, who are known to be high achievers at school and in other areas of life (Frost 2015).

 

These differences within West Africa support the argument that mean cognitive ability has continued to increase in some human populations, even in relatively recent times. With respect to the Yoruba, their cognitive ability may have increased in tandem with their advances in trade, urban settlement, and State formation from the tenth century onward (Akintoye 2014; McIntosh and McIntosh 1988). Meanwhile, the Mende remained at a lower level of social complexity.

 

There is one problem with using polygenic scores for West Africans, or for any non-European population. To identify alleles associated with higher educational attainment, researchers have used genomes of European origin. There is evidence, however, that the architecture of cognitive ability may differ in different human populations. The same alleles might not explain high cognitive ability in West Africans and Europeans. Indeed, Lasker et al. (2019) found a lower correlation between polygenic scores and cognitive ability in African Americans than in European Americans.

 

References

 

Akintoye, S.A. (2014). A History of the Yoruba People. Dakar: Amalion.

 

Frost, P. (2015). The Jews of West Africa. The Unz Review, July 4

https://www.unz.com/pfrost/the-jews-of-west-africa/

 

Lasker, J., B.J. Pesta, J.G.R. Fuerst, and E.O.W. Kirkegaard. (2019). Global ancestry and cognitive ability. Psych 1(1)

https://www.mdpi.com/2624-8611/1/1/34  

 

McIntosh, S.K., and McIntosh, R.J. (1988). From stone to metal: New perspectives on the later prehistory of West Africa. Journal of World Prehistory 2: 89-133. https://doi.org/10.1007/BF00975123  

 

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. (2021). Divergent selection on height and cognitive ability: evidence from Fst and polygenic scores. OpenPsych

https://openpsych.net/files/submissions/14_Divergent_selection_on_height_and_cognitive_ability_evidence_from_Fst_and_13c3ICJ.pdf  

Differences in the genetic architecture of cognition?

Tableau III, Piet Mondrian (1872-1944). The polygenic score can provide a measure of innate cognitive ability in various human populations. However, it is less valid for African Americans, apparently because of differences in the genetic architecture of cognition.



When IQ is measured in European Americans and African Americans, the two groups differ on average by about 15 points. Is the difference genetic? Or is it due to different environments?

After years of debate, we are coming close to an answer. The weight of evidence is shifting, especially because of two unrelated developments: 

- We can now easily measure ethnic ancestry by means of genetic data. Previously, we had to rely on self-report or indirect measures like skin color.

- We can now measure the genetic component of cognitive ability: the polygenic score. This score is a summation of alleles associated with high educational attainment. Initially a crude measure, it is getting better and better as we identify more and more of these alleles.

Both research tools were used in a recent study. Lasker et al. (2019) applied them to the Philadelphia Neurodevelopmental Cohort, a sample of 9421 individuals from the Philadelphia area who received medical care from the Children's Hospital of Philadelphia network. They ranged in age from 8 to 21 with a mean of 14.2. They were 51.7% female, 55.8% European American, 32.9% African American, and 11.4% other. All of them were genotyped and given a series of cognitive tests.

This dataset had advantages over those of previous studies:

- All participants came from the same geographic area. 

- Heritabilities of cognitive ability were already estimated by another research team, specifically 0.61 for the African American participants and 0.72 for the European American participants.

- Skin, hair, and eye color could be estimated from the genetic data to control for the effects of "colorism" (discrimination favoring lighter-skinned over darker-skinned African Americans)

- Polygenic scores could be calculated from the genetic data

The main disadvantage was the participants’ young age. Before adulthood the brain is plastic and still developing, so the heritability of cognitive ability is lower. 


IQ results

IQ scores were 100 for European Americans, 98 for self-described biracial Americans, and 85 for African Americans. The three groups were respectively 99% European, 80% European, and 19% European.

African Americans only

European admixture significantly correlated with IQ among the African American participants. The correlation remained significant after controlling for either skin color or socioeconomic status. Interestingly, skin and hair color didn't significantly correlate with IQ independently of European admixture, but eye color did. Brown eyes correlated positively with IQ. No explanation was offered by the authors. Did they get the same finding with European Americans?

Biracial Americans only - smarter than expected

As with African Americans, skin color didn't seem to influence intelligence independently of European admixture. On the other hand, "biracial status had a significant effect independently of European ancestry." In other words, racially mixed individuals who identified equally as African American and European American, and not just as African American, tended to be more intelligent than what their degree of European admixture would predict. 

The term "biracial" as a badge of identity is recent and seems to be most popular among middle-class people: 

Interestingly, many of the respondents here who identify as biracial are middle class, educated in private schools, and raised in predominantly white neighborhoods with mostly white social networks (Rockquemore and Brunsma 2008, p. xxii)

It may be, then, that self-identified "biracial" people have parents who are, on average, of higher quality than other people of the same racial background.

African Americans, Biracial Americans, and European Americans combined

When all three groups were combined, the most important factor was European admixture. Next came socioeconomic status, which correlated with cognitive ability independently of European admixture. Finally, self-identification as a European American had an effect over and above that of European admixture. The last factor suggests that European American culture has a positive influence on cognitive ability.


Polygenic score results

The polygenic scores ran into a problem that others have noted: the genetic architecture of cognition seems to be different in African Americans. This is a problem because researchers have used only Europeans or European Americans to identify genetic variants that are associated with high educational attainment. Those variants did correlate with cognitive ability in the African American sample, but to a much lower degree than in the European American sample. Their validity as a measure of cognitive ability was only 20% of what it was in the European American sample.

The authors used a subset of the same variants to create a polygenic score that would be less sensitive to linkage disequilibrium decay and thus more valid across different human populations. This polygenic score had good validity in both the African- and European-American samples (r = 0.112 and r = 0.227 respectively).

The authors then tried to create an even better polygenic score by excluding variants that are rare in African Americans. There was no effect on the results for either African Americans or European Americans. But what about the reverse? Perhaps cognitive ability is improved by some variants that are rare in European Americans but common in African Americans.


Conclusion

This is an excellent study, on a par with the Minnesota Transracial Adoption Study (Frost 2019). The main problem is the participants’ young age. Had adults been used, there would have been less noise in the data, and the results would have been better.

Another problem is the apparently different genetic architecture of cognition in people of sub-Saharan African origin. Piffer (2019) has noted that polygenic scores underestimate African American IQ. He disagrees, however, with the "different genetic architecture" hypothesis, pointing out that no divergence exists between mean population IQ and the polygenic scores he has calculated for various sub-Saharan African groups (Esan, Gambians, Luhya, Mende, Yoruba). None of them, however, are Igbo, and the Igbo are really the one group that stands out from other West Africans on measures of intellectual and educational attainment (Frost 2015a, 2015b). They also contributed to the gene pool of African Americans: "Many of the enslaved Igbo people in the United States were concentrated in Virginia's lower Tidewater region and at some points in the 18th century they constituted over 30% of the enslaved black population" (Wikipedia 2019).

While the polygenic score is a good measure of raw cognitive ability in most humans, we need to develop a modified version for people whose ancestry comes primarily from sub-Saharan Africa.


References

Frost, P. (2015a). The Jews of West Africa? Evo and Proud, July 4
http://evoandproud.blogspot.ca/2015/07/the-jews-of-west-africa.html 

Frost, P. (2015b). No, blacks aren't all alike. Who said they were? Evo and Proud. October 10.
http://evoandproud.blogspot.com/2015/10/no-blacks-arent-all-alike-who-said-they.html 

Frost, P. (2019). IQ of biracial children and adults. Evo and Proud. March 10.
http://evoandproud.blogspot.com/2019/03/iq-of-biracial-children-and-adults.html

Lasker, J., B.J. Pesta, J.G.R. Fuerst, and E.O.W. Kirkegaard. (2019). Global ancestry and cognitive ability. Psych 1(1)
https://www.mdpi.com/2624-8611/1/1/34 

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://www.mdpi.com/2624-8611/1/1/5  

Rockquemore, K.A. and D.L. Brunsma. (2008). Beyond Black. Biracial Identity in America. Lanham: Rowman & Littlefield Publishers.
https://books.google.ca/books?id=Nf0eAAAAQBAJ&printsec=frontcover&hl=fr&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Wikipedia. (2019). Igbo Americans. 
https://en.wikipedia.org/wiki/Igbo_Americans

They really are smart ... and other surprises

Rachela - Maurycy Gottlieb (1856-1879) (Wikicommons). Ashkenazi Jews have a higher incidence of genetic variants associated with high educational attainment.



Intelligence varies from one individual to the next, and most of this variance has genetic causes. But what, exactly, are these causes? Lots and lots of genes, it seems. To be precise, if we look at the genes that influence human intelligence, we find two things:

1. They are very numerous, numbering in the thousands.

2. In general, their variants differ slightly in their effects.

This shouldn't be surprising. Evolution proceeds by tinkering, i.e., by making little changes. Big changes tend to produce big side-effects, and most side-effects are deleterious. So the genetic capacity for intelligence differs among humans through small differences at thousands upon thousands of genes. Does it follow, then, that we cannot understand these differences by looking only at a few genes? Not necessarily. Each gene is like a weathervane. If you can get enough subjects from a human population, even a few genes will tell you the direction and strength of natural selection for intelligence. 

Davide Piffer began looking at these “weathervanes” six years ago. He gathered data from different human populations on ten SNPs (single nucleotide polymorphisms) whose genetic variants are associated with differences in intelligence, specifically differences in educational attainment. Then, for each population, he estimated its genetic capacity for intelligence by calculating a "polygenic score"—the number of genetic variants associated with higher educational attainment, out of a maximum of ten.

This score correlated with population IQ (r=0.90) and with PISA scores (r=0.84). It was highest in East Asians:

East Asians have the highest frequencies of alleles beneficial to educational attainment (39%) and consistently outperform other racial groups both within the US and around the world, in terms of educational variables such as completion of college degree or results on standardized tests of scholastic achievement. Europeans have slightly lower frequencies of educational attainment alleles (35.5%) and perform slightly worse in terms of educational attainment, compared to East Asians. On the other hand, Africans seem to be disadvantaged both with regards to their level of educational attainment in the US and around the world. Indeed, Africans have the lowest frequencies of alleles associated with educational attainment (16%). (Piffer 2013)

These results were considered preliminary. Thousands upon thousands of genes influence intelligence, and here we have only ten! Perhaps chance alone produced this geographic pattern. Over the next few years, as other researchers discovered more SNPs associated with educational attainment, Davide Piffer repeated his study with more of these weathervanes.

His latest study has just come out. It uses data on 2,411 SNPs, and the polygenic score correlates even higher with population IQ (r=0.98). The geographic pattern is the same, with East Asians scoring higher than Europeans, and with Africans scoring lower.


Yes, Jews really are smart

This time, however, the highest score was obtained for Ashkenazi Jews: 

This dataset included a sample of 145 Ashkenazi Jewish individuals. The IQ of Ashkenazi Jews has been estimated to be around 110 [34]. Remarkably, their EDU polygenic score was the highest in our sample, corresponding to a predicted score of about 108, mirroring preliminary results from a smaller (N = 53) sample (Dunkel et al., 2019) [34]. (Piffer 2019)

This finding vindicates the authors of a paper written more than a decade ago. Gregory Cochran, Jason Hardy, and Henry Harpending presented evidence that the mean IQ of Ashkenazi Jews exceeds not only that of non-Jewish Europeans but also that of other Jewish groups. The most striking piece of evidence is the high incidence among Ashkenazim of four genetic disorders: Tay-Sachs, Gaucher, Niemann-Pick, and mucolipidosis type IV (MLIV). All four affect the capacity to store sphingolipid compounds that promote the growth and branching of axons in the brain. These disorders are caused by alleles that are harmful in the homozygote state and beneficial in the much more common heterozygote state, i.e., the brain receives higher levels of sphingolipids without the adverse health effects.

Ironically, these facts are coming to light at a time when Ashkenazi Jews are disappearing through low fertility and high out-marriage. Meanwhile, and not coincidentally, they are disappearing from the ranks of top winners at the U.S. Math Olympiad, the Putnam Exam, the Computing Olympiad, and other academic competitions. This decline became noticeable in the 1980s and has accelerated since the turn of the millennium (Unz 2012; Frost 2018). Jews are still present in intellectual and cultural life, but this presence is losing its dynamism and becoming a mere legacy.


African American IQ is higher than predicted

The polygenic score seems to underpredict the IQ of African Americans:

Indeed, the IQ of African Americans appears to be higher than what is predicted by the PGS (Figure 2), which suggests this cannot be explained by European admixture alone, but it could be the result of enjoying better nutrition or education infrastructure compared to native Africans. Another explanation is heterosis ("hybrid vigor"), that is the increase in fitness observed in hybrid offspring thanks to the reduced expression of homozygous deleterious recessive alleles. (Piffer 2019)

I’d propose another possible explanation: higher intelligence in African Americans may be associated with a somewhat different basket of genetic variants. Some of these variants may come from our friends the Igbos, who seem to have followed their own evolutionary path toward higher intelligence (Frost 2015). Many notable African Americans are in fact of Igbo descent, including Forest Whitaker, Paul Robeson, and Blair Underwood (Wikipedia 2019).

Davide is skeptical about this explanation, pointing out that population IQ is in line with the polygenic score he calculated for sub-Saharan African groups (Esan, Gambians, Luhya, Mende, Yoruba). None of those groups, however, are Igbo, and it's really the Igbo who stand out among West Africans in measures of intellectual and educational attainment. If only for the sake of curiosity, we should find out their polygenic score. This score may underpredict their genetic capacity for intelligence, which to some degree would be boosted by genetic variants that exist only in sub-Saharan Africa, but it should still exceed what we see for other West Africans.


Conclusion

This latest study brings to 2,411 the number of SNPs that can inform us about the genetic capacity for intelligence in different human populations. This information was more dubious when only ten SNPs were available, and the geographic pattern could be put down to chance. That argument now seems weak. If chance is causing this pattern, why do we keep getting the same one?

Sure, we can wait until we get even more relevant SNPs, but the overall picture will probably remain the same. We will get finer geographic detail. In France, for example, we will probably understand why educational attainment is so much higher in Brittany (see:  http://www.targetmap.com/viewer.aspx?reportId=5987  H/T to Philippe Gouillou). There are probably several European regions and subregions where the genetic capacity for intelligence is on a par with what we see in Ashkenazi Jews and East Asians.

In sum, these findings deserve to be better known ... and more widely discussed.


Erratum

Initially, I wrote that Davide Piffer used 127 SNPs. In fact, 127 is the number of SNPs found in the HGDP (low coverage) dataset. In the other two datasets (1000 Genomes and GnomAd), those that the main analysis was based on, there were actually 2,411 SNPs.


**** Hiatus alert ****

I'll be unable to post for the near future, probably the next three months. 


References

Cochran, G., J. Hardy, and H. Harpending. (2006). Natural history of Ashkenazi intelligence, Journal of Biosocial Science 38: 659-693.
https://antville.org/static/sites/kratzbuerste/files/AshkenaziIQ.pdf   

Frost, P. (2018). The end of Jewish achievement? Evo and Proud, May 21
http://evoandproud.blogspot.com/2018/05/the-end-of-jewish-achievement.html

Frost, P. (2015). The Jews of West Africa, Evo and Proud, July 4
https://evoandproud.blogspot.com/2015/07/the-jews-of-west-africa.html

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://www.mdpi.com/2624-8611/1/1/5

Piffer, D. (2013). Factor analysis of population allele frequencies as a simple, novel method of detecting signals of recent polygenic selection: The example of educational attainment and IQ, Mankind Quarterly 54(2): 168-200
https://www.researchgate.net/profile/Davide_Piffer/publication/260436834_Factor_Analysis_of_Population_Allele_Frequencies_as_a_Simple_Novel_Method_of_Detecting_Signals_of_Recent_Polygenic_Selection_The_Example_of_Educational_Attainment_and_IQ/links/0c9605314d28dba7ea000000/Factor-Analysis-of-Population-Allele-Frequencies-as-a-Simple-Novel-Method-of-Detecting-Signals-of-Recent-Polygenic-Selection-The-Example-of-Educational-Attainment-and-IQ.pdf 

Unz, R. (2012). The myth of American meritocracy. The American Conservative, November 28
http://www.theamericanconservative.com/articles/the-myth-of-american-meritocracy/   

Wikipedia (2019). Igbo people.
https://en.wikipedia.org/wiki/Igbo_people#Diaspora

A new yardstick

If we look at ancient DNA from 4,560 to 1,210 years ago, we see a steady increase over time in the number of genetic variants that are linked to high educational attainment (Woodley et al. 2017)

Four years ago I discussed genetic variants that seem to favor high educational attainment (Frost 2014). They’re found at single nucleotide polymorphisms (SNPs), and their incidence varies from one human population to another. In all but one case, they are specific to humans and not shared with ancestral primates. 

Davide Piffer has been interested in these SNP variants, seeing them as a possible way to measure how genes contribute to intelligence in different populations. By looking up population data, he can calculate their average incidence for a given group of people. This measure is called the “cognitive polygenic score.”

When he wrote up his latest paper (Piffer 2017a), only nine of these variants were known. For each geographic region, the scores were as follows:

Sub-Saharan Africans – 18%

Amerindians – 25%
North Africans – 30%
Oceanians (Papuans, Melanesians) – 34%
Southeast Asians – 35%
West Asians – 38%
Middle Easterners – 40%
Europeans – 41%
Siberians – 43%
East Asians – 45%

This regional breakdown is open to criticism. Sardinians (32%) were not included in the European category, and Mongolians (49%) were grouped with East Asians rather than with Siberians. The distinction between Middle Easterners and West Asians is not clear to me. The Amerindian category is based on a few small groups. And who is included in the Southeast Asian category? Only Cambodians?

When Piffer compared these scores with the results of IQ tests in these regions, he found a high correlation of 0.9. That is high, higher than what I would expect, given the quality of the data, especially for mean IQ, and the very disparate nature of the two datasets.

Over a two-year period Piffer submitted his paper to Intelligence, resubmitted it, had it rejected, and then resubmitted it to Frontiers in Psychology, where it was accepted by the reviewers before being rejected by the editor. It is now sitting in the limbo of a preprint repository (Piffer 2017a).

Meanwhile, the number of these SNPs has continued to grow. A research team led by Aysu Okbay identified 74 SNPs that are associated with educational attainment (Okbay et al. 2016). Another team led by David Hill reported 107 in their initial preprint and 187 in their published paper (Hill et al. 2018). 

Piffer (2017b) repeated his analysis, now using the 107 SNPs that Hill’s team had identified. The geographic pattern still held up but was weaker, the correlation being only 0.64. This lower score is actually more in line with what I would expect. It diverges the most from mean IQ in two geographic areas:

1. South Asia (Pakistan, India) - South Asians seem to do worse on IQ tests than their genetic endowment predicts. Why? Is it the culture? The diet? Inbreeding? Perhaps language. IQ tests are often administered in a language (English, Hindi, Urdu) that may be the second language of the person taking it. Or perhaps South Asian educational attainment is determined not only by IQ but also by qualities like the ability to sit still and not make a ruckus in class.

2. The Mende of Sierra Leone - For some reason, the Mende have a higher cognitive polygenic score than any other African population. This might be a real finding, or a typo.

Another research team, led by Michael Woodley, has compared the Okbay dataset with ancient DNA to see whether the cognitive polygenic score has increased over time, specifically between 4,560 and 1,210 years ago. The DNA was retrieved from European sites and a few sites from southwest and central Asia. The result? The cognitive polygenic score did increase over time. People on average had more and more of the alleles that favor educational attainment. The authors note that IQ alone may not be responsible:

[...] While the increase in these variants over time is certainly consistent with the expectation of rising GCA [general cognitive ability], the possibility that their increase indicates a simultaneous rise in other factors that make unique contributions to educational attainment (such as 'slow' life history or 'high-K' social cognitive characteristics) cannot be ruled out. (Woodley et al. 2017; references within quote removed)

The new mental/behavioral package developed through a process of feedback with the cultural environment. This gene-culture coevolution likely continued into recent times:

This process likely continued until the Late Modern Era, where it has been noted that among Western populations living between the 15th and early 19th centuries, those with higher social status (which shares genetic variance with, and is therefore a proxy for GCA) typically produced the most surviving offspring. These in turn tended toward downward social mobility due to intense competition, replacing the reproductively unsuccessful low-status stratum and effectively 'bootstrapping' those populations via the application of high levels of skill to solving problems associated with production and industry, eventually leading to the Industrial Revolution in Europe. (Woodley et al. 2017; references within quote removed)

Conclusion

More and more SNPs are being linked to educational attainment. The total is now in the triple digits. That’s still less than the thousands of genes that influence intelligence, but there is no need to identify most of them to spot general trends. Selection acts on phenotype, not on genotype. Selection for intelligence should therefore impact all of these SNPs in the same direction. It’s like estimating the proportions of different colors in a bowl of Smarties. You don’t have to count every last one. Just pick out a handful at random and count the colors.

Four years ago only 7 SNPs had been linked to educational attainment. Now we have 187. In another four years we’ll probably have more than a thousand. All the same, I doubt that the overall geographic pattern will change much. The problems lie elsewhere:

-          Genetic data may be lacking for some unmixed groups, particularly Amerindians.

-          The relationship between intelligence and cognitive polygenic score may not be linear.

-          We may be relying too much on educational attainment as a proxy for IQ (which itself is a proxy for intelligence).

When I was in public school, girls did better than boys in almost every subject. They had good attendance, always took notes, and did their homework. Boys got bored more easily and spent more time fidgeting, daydreaming, and drawing pictures in their notebooks. This sex difference exists in all cultures, but it seems greater in some than in others.

How useful is educational attainment as a proxy for IQ? Yes, these two measures correlate highly with each other (Rindermann 2018, pp. 51-54), but this high correlation is based on studies from WEIRD countries (Western, educated, industrialized, rich, and democratic). Does it hold up on a global scale? I’m not so sure.

References

Frost, P. (2014). Population differences in intellectual capacity: a new polygenic analysis, Evo and Proud, March 8

http://evoandproud.blogspot.ca/2014/03/population-differences-in-intellectual.html

Hill, W. D., R.E. Marioni, O. Maghzian, S.J. Ritchie, S.P. Hagenaars, A.M. McIntosh, C.R. Gale, G. Davies, I.J. Deary. (2018). A combined analysis of genetically correlated traits identifies 187 loci and a role for neurogenesis and myelination in intelligence. Molecular Psychiatry

https://doi.org/10.1038/s41380-017-0001-5

Okbay, A., J.P. Beauchamp, M.A. Fontana, J.J. Lee, T.H. Pers, C.A. Rietveld, et al. (2016). Genome-wide association study identifies 74 loci associated with educational attainment. Nature 533: 539-542.

http://www.nature.com/articles/nature17671

Piffer, D. (2017a) Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from GWAS Hits: A Replication of Previous Findings Using Recent Data. Preprints, June 8

https://www.preprints.org/manuscript/201706.0039/v1

Piffer, D. (2017b). Piffer's results replicated (again) by latest GWAS (N=147,194), toppseudoscience, July 21

https://topseudoscience.wordpress.com/2017/07/21/piffers-results-replicated-again-by-latest-gwas-n147194/comment-page-1/#comment-95

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

Woodley, M.A., S. Younuskunju, B. Balan, and D. Piffer. (2017). Holocene selection for variants associated with general cognitive ability: comparing ancient and modern genomes. Twin Research and Human Genetics 20(4): 271-280.

https://doi.org/10.1017/thg.2017.37