2. Recent cognitive evolution in West Africa

My wish list for research in 2024

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