The latter trade led to the rise of both Abomey (in Benin) and Kumasi (the Ashanti capital now in Ghana) which also had populations that were quite a bit larger than 10,000. The reader doesn’t mention any of the Yoruban city states but they were also reputedly larger than 10K. Several of these “states” had increased populations, both from the influx of slaves and refugees from slave wars, but the areas around them were often depopulated in consequence of the demand for slaves for export to the Americas.

There were also some cities in Southern Africa, such as the capital of Botswana that had about 30-50,000.

These cities were as large as many capital cities in Europe before the industrial revolution.

That doesn’t impact either their discovery, or the fact that population size increases in West-Central African cities exponentially increased about the time they mention. What this suggests is that traditional patterns of sexual activity broke down as male migrants moved to cities (some of which were associated with mining activities), and perhaps there was an increased demand for “bush-meat” as rural pastoralism decreased as men took on other employment. The policies of many mining and other industrial firms was that women were to remain in their home villages and that the men were to live in dormitories. That inevitably led to alienated men seeking sex elsewhere, and yet carrying any sexually-transmitted diseases back to their wives when they returned home.

That said, these cities were often spread across landscapes much larger than the modern cities of West-Central Africa and none reached the hundreds of thousands or millions that todays African cities attain.

Reconstructing the emergence of the AIDS virus in West Africa shows how larger sociopolitical and economic factors (colonialism, urbanization, trade, travel) conspired to produce one of today’s most horrific and devastating pandemics. This kind of insight is not especially empowering, since there is not much we can do directly about these events. We are at the mercy of a complex and interconnected “system.” We can’t stop it from happening. The best we can do is prepare to manage the consequences.

Which brings us back to where we almost always wind up, here. Managing the consequences means building a robust, resilient and flexible public health and social service infrastructure. We haven’t done it and we aren’t doing it. It isn’t clear we are even planning to do it or even thinking of doing it. So we will again surely reap the whirlwind that science, history and experience tell us happens with regularity.