This seems a bit odd. The Atlantic Congo and Mende speakers in Sengambia, Mali, Burkina Faso had centuries of exposure to trade with cetral and north Africa, and Arabic literacy. They also lived in some of the most organized large scale states in African history. This was specifically lesld by Mende and then Fulani speakers. That produced no cognitive load or selection pressure? Somehow though Nigeria, far more isolated environment did in much less time?
Is it something to do with farming vs herding? Population density?
This seems a bit odd. The Atlantic Congo and Mende speakers in Sengambia, Mali, Burkina Faso had centuries of exposure to trade with cetral and north Africa, and Arabic literacy. They also lived in some of the most organized large scale states in African history. This was specifically lesld by Mende and then Fulani speakers. That produced no cognitive load or selection pressure? Somehow though Nigeria, far more isolated environment did in much less time?
Is it something to do with farming vs herding? Population density?