West Africa and recent cognitive evolution

Map of the Niger and its drainage basin (Wikicommons)

In West Africa, mean cognitive ability seems to be higher in populations closer to the Niger—the main conduit of trade between the coast and the interior. Trade selects for cognitive ability, either directly through its cognitive demands or indirectly through a consequent increase in social complexity.

Cognitive evolution did not end when Homo sapiens began. It continued at different rates and in different ways in different populations. In some populations it may have even accelerated. Humans adapt not only to the demands of slow-changing natural environments but also to the demands of faster-changing cultural environments. Culture is no less crucial than climate in determining who gets to live and reproduce. If you can better cope with your culture and its cognitive demands, you will be better at passing on your mental and behavioral traits to the next generation.

All of that is no less true for the populations of West Africa. Before Europeans arrived, West African societies were more complex in the north and the east, i.e., in the drainage basin of the Niger. From the 4th century onward, that region saw the creation of towns, the formation of elites, the development of metal-working, and the expansion of trade over long distances.

That increase in social complexity used to be attributed to the influence of Arab traders from North Africa and the Middle East, but we now have archaeological evidence of urbanism and long-distance trade as far back as 300 AD, long before the arrival of Arab traders (McIntosh and McIntosh, 1988, pp. 114-116). A 9th-century site in the Niger Delta has yielded bronze objects that show little if any Arab influence. The bronze has an unusually high silver content and only traces of zinc, an alloy not used in either Europe or the Muslim world at that time (McIntosh and McIntosh, 1988, pp. 120-121).

While the increase in social complexity was undoubtedly assisted by Arab traders and, later, European traders, it seems to have begun as an indigenous development along the Niger, which served as West Africa’s main trading route between the coast and the interior:

In the case of the Middle Niger and the Nigerian forest, trade has figured prominently in explanations of increasing complexity. Local or regional trade in kola (at Ife) and stone and iron (at Jenne-jeno) are postulated as the small-scale beginnings of exchange systems that rapidly expanded. […] such goods were but the visible tip of a vast iceberg of archaeologically undetectable trade commodities, such as slaves, food staples, condiments, salt, and oil […]. The natural ecological zonation of the subcontinent would have encouraged exchange of foodstuffs and salt between adjacent zones from very early on. (McIntosh and McIntosh, 1988, p. 122)

Trade was “as much a symptom as a cause of complexity.” It provided powerful individuals with the materials they needed to erect buildings, create works of art, and hold ceremonies to legitimize and further increase their power. They could then buy even more of the same materials. In sum, social complexity was driven by a positive feedback loop: the buying power of elites increased trade, which in turn increased their buying power (McIntosh and McIntosh, 1988, p. 123).

Thus, as trade increased within the Niger drainage basin, so did social complexity. Did this new environment select for cognitive ability? Davide Piffer has calculated the polygenic scores of alleles associated with educational attainment for several West African populations. He found that mean cognitive ability seems to increase from west to east, with the polygenic score being lowest for the Mende (Sierra Leone) and progressively higher for Gambians, the Esan (Nigeria), and the Yoruba (Nigeria). The Yoruba have almost the same polygenic score as do African Americans, who are nonetheless about 20% European by ancestry (Piffer, 2021, see Figure 7).

Bronze vessel in the shape of a snail shell, Igbo-Ukwu, 9th century, (Wikicommons – Ochiwar)

The Igbo people

It’s a pity that we have no polygenic data on the Igbo (formerly the Ibo), who live at the Niger’s mouth and who seem to have gone the farthest on this trajectory of cognitive evolution. Indeed, Igbo children excel at school:

The superior Igbo achievement on GCSEs is not new and has been noted in studies that came before the recent media discovery of African performance. A 2007 report on "case study" model schools in Lambeth also included a rare disclosure of specified Igbo performance […] and it confirms that Igbos have been performing exceptionally well for a long time (5 + A*-C GCSEs); in fact, it is difficult to find a time when they ever performed below British whites. (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 observations, from the eighteenth century, describe them as “competitive, individualistic, status-conscious, antiauthoritarian, pragmatic, and practical—a people with a strongly developed commercial sense” (Mullin, 1994, p. 286). West Indian slave-owners saw them as adept at learning English. “In Jamaican descriptions of all named peoples, Ibo were the most adroit in using language distinctively and in some instances deceptively” (Mullin, 1994, pp. 286-287).

That mindset helped them dominate trade:

In study after study, it has been documented that the Ibo, through conflict and mobility, have been very successful in enterprise. Indeed, a major study argued that the Ibo have a very high need for achievement in the business world. Still another study showed that the majority of entrepreneurs in the sample were Ibo. (Butler, 1997, p. 178)

By the time of independence they dominated most areas of life:

All over Nigeria, Ibos filled urban jobs at every level far out of proportion to their numbers, as laborers and domestic servants, as bureaucrats, corporate managers, and technicians. Two-thirds of the senior jobs in the Nigerian Railway Corporation were held by Ibos. Three-quarters of Nigeria's diplomats came from the Eastern Region. So did almost half of the 4,500 students graduating from Nigerian universities in 1966. (Baker, 1980)

By that time, too, they accounted for 24 of the 52 senior army officers with a rank of major or higher (Ibrahim, 2000, p. 55).

Igbo dominance led to jealousy, as well as accusations of unfair business practices: “In the private sector they [the Hausa Muslims] are open to the exploitation of the Ibo control of the modern sector of private business activities. Ibos fix prices unilaterally by which Hausa money is siphoned daily. The Hausa are reduced to utter poverty and a large percentage of them rendered street beggars” (Ibrahim, 2000, p. 52). The situation was summed up by Henry Kissinger in a memorandum to President Nixon: “The Ibos are the wandering Jews of West Africa — gifted, aggressive, Westernized; at best envied and resented, but mostly despised by the mass of their neighbors in the Federation” (Kissinger, 1969).

When Nigeria became independent, the Igbo lost some of their dominance. Independence brought majority rule, and they were not the majority. They began to resent the new government, seeing it not only as beyond their control but also as corrupt, incompetent, and fraudulent. In 1966, a group of Igbo officers carried out a coup d’état and executed the Prime Minister, the Premier of the Northern Region, and the Premier of the Western Region. There then came a counter-coup and a wave of persecution that took the lives of eight thousand to thirty thousand Igbo. Between one and two million fled to their homeland in the Eastern Region. Then, having learned that the new government intended to split their region into three parts, they declared their independence and named the new country “Biafra.” Thus began the Nigerian Civil War.

Igbo prehistory

The Igbo specialized in trade at an early date, thanks to their location at the Niger’s mouth and their role as middlemen in exchanges between the coast and the interior. Assemblages of glass beads, many of Egyptian origin and dating to the 9th and 14th centuries, have been recovered from the Niger Delta and eastern Mali, indicating that the Niger acted as a conduit of trade from the Atlantic to the Sahel and thence to the Middle East (Davison, 1972; Insoll and Shaw, 1997).

Economic development began much earlier in the Niger Delta than elsewhere in West Africa, as shown by early development of metal-working. At one site, dated to 765 BC, iron ore was smelted in furnaces that measured a meter wide. The molten slag was drained to collecting pits, where it formed blocks weighing up to 43-47 kg. The operating temperatures are estimated to have been 1,155 to 1,450 °C (Holl, 2009). Some radiocarbon dates for iron smelting in the region go back as far as 2000 BC (Eze-Uzomaka, 2009).

Metal-working not only arose earlier among the Igbo but also reached a higher level of sophistication, as seen in the more than 700 artefacts of bronze, copper, and iron from the Igbo-Ukwu site. Dated to the 9th century, the bronze artefacts are the oldest known ones from West Africa and include numerous ritual vessels, pendants, crowns, breastplates, staff ornaments, swords, and fly-whisk handles. They show a degree of artistic proficiency that exceeded that of contemporary bronze casting in Europe. This metal-working tradition seems to have arisen independently of metal-working in the Middle East and Europe:

Apparently the metal workers of ancient Igbo-Ukwu were not aware of commonly used techniques such as wire making, soldering or riveting which suggests an independent development and long isolation of their metal working tradition. [...] Some of the techniques used by the ancient smiths are not known to have been used outside Igbo-Ukwu such as the production of complex objects in stages with the different parts later fixed together by brazing or by casting linking sections to join them. (Wikipedia, 2022)

Production seems to have exceeded local needs: “the Lejja smelters must have had excess production of iron, and this may have led to extensive trade to far and distant places, sustained over a long period of time” (Eze-Uzomaka, 2009). Thus, even before the first European contacts, the Igbo were already at the center of a trade network that radiated outward from the Niger Delta. That network would eventually include European traders:

The peoples of south-eastern Nigeria have been involved in trade for as long as there are any records. The archaeological sites at Igbo-Ukwu and other evidence reveal long distance trade in metal and beads, as well as regional trade in salt, cloth, and beads at an early date. The lower Niger River and its Delta featured prominently in this early trade, and evidence is offered [in this paper] to suggest a continuity in the basic modes of trade on the lower Niger from c. A.D. 1500 to the mid-nineteenth century. (Northrop, 1972)

Conclusion

Trade selects for cognitive ability, either directly through its cognitive demands or indirectly through a consequent increase in social complexity. This has been the case with the Igbo, as it has been with the Ashkenazi Jews, the Parsis, and other trading peoples (Cochran et al., 2006; Frost, 2012; Frost, 2021). Those communities all bear witness to recent cognitive evolution. There is in fact a growing consensus that cognitive ability continued to evolve into the time of recorded history, as did evolution for other traits (Cochran and Harpending 2009; Hawks et al., 2007; Rinaldi, 2017).

In West Africa, cognitive evolution has gone farther in some populations than in others. In particular, it seems to have gone the farthest in populations close to the Niger, where pre-colonial trade and social complexity were the most developed. It seems, then, that cognitive ability coevolved with the demands of the local cultural environment. It is to be hoped that researchers will investigate this gene-culture coevolution by collecting genomic data from the Igbo and other Niger-dwelling peoples, particularly with respect to alleles associated with educational attainment.

References

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