From Francis Fukuyama’s The Origins of Political Order: From Prehuman Times to the French Revolution
Though the human species got its start in Africa, human beings have thrived better in other parts of the world. Population densities had always been low throughout the continent until the arrival of modern agriculture and medicine; it was not until 1975 that Africa reached the population density that Europe enjoyed in the year 1500. Parts of Africa that are exceptions to this generalization, like the fertile Great Lakes region and the Great Rift Valley, have supported much higher population densities and indeed saw the early emergence of centralized states.
I predict that this is a book people will want to pretend to have read over the years, so if you plan on actually reading it (which I think you should) it’s important to memorize some random factoids like this in order to be able to prove you went through the whole thing.