Of Stink Bugs and Africa

by Doctor Science

Some interesting points and question have come up in the comments to Of Stink Bugs and Men. First, I'm going to round up the ones that are principally about Africa.

Scott P. said:

Africa has 20% of the world's land area, and in 1500 it apparently had 16% of the world's population.

Good point! But land area is the wrong thing to be comparing, because much of the earth's surface is too dry or too cold to have supported a heavy human population in pre-modern times. If you look at population density in the Old World today:


(from Columbia's Socioeconomic Data & Applications Center)
you see that SS (sub-Saharan) Africa has much lower population densities than in comparable areas of Asia, such as south India and Indonesia. This is true even though rice was independently domesticated in West Africa, parallel to its domestication in India and China. This map of cultivation intensity:


(from Global Patterns of Cropland Use Intensity (PDF))
gives an even more persuasive picture. You can see that the rice areas of west Africa are now being farmed intensively, but this is a relatively recent phenomenon and the population hasn't had built up to the levels you see in Bangladesh, Java, or south China.

In Africa: The Biography of a Continent John Reader repeatedly emphasizes that even before the slave trade, human populations in SS Africa don't seem to have been constantly exporting people for war or trade the way we're familiar with from west Asian/European history. One of the exceptions is Ukara island in Lake Victoria:

Not only was the island able to sustain an exceptionally high rural population density, it also produced a surplus population that moved out and settled elsewhere ... There is no spare land awaiting clearance and cultivation on Ukara

-- in contrast to most other parts of SS Africa, where there was usually more farmable land than there were people to farm it. What really caught my attention was:

Though a shortage of land stimulated the development of intensive and sustainable agricultural strategies on Ukara, there were other factors contributing to its success. The absence of the tsetse fly and trypanosomiasis, for instance, enabled the islands to keep cattle

-- which I personally theorize is less important than that the humans were healthier, too. My guess is that sleeping sickness wasn't the only parasite lacking on Ukara, so the human population there experienced what RogueDem reminds me is called "ecological release".

One reason the comparative under-population of Africa hasn't seem like something that needs explanation is that South America seems so similar. Large areas of the Congo rain forest are undisturbed by humans, but then so are even larger areas of the Amazon. Tropical rain forests just don't look like very good places to raise crops and humans.

But in recent decades archaeology has been tipping our image of the 1491 Amazon on its head. Patches of fertile, black soil within the "virgin" rain forest turn out to be artificial; there are remnants of raised fields and constructed fisheries in the jungle; the pre-Columbian inhabitants, far from being "primitive", were engaged in ecological engineering on a frankly staggering scale.

I suggest that ecological engineering was possible in the Amazon basin and not in the Congo because of disease. Malaria was (probably) not a problem in pre-Columbian South America; it has been one of the most important human diseases in Africa for thousands of years at least. Similar African habitats also seem to have been sources for a number of "new" diseases in the past century: HIV, Ebola, Lassa fever; I think there are probably lots more where those come from.

Comments

[Chris J]

I think you're correct about malaria, particularly the more severe falciparum form found in Africa.

Related, there's an excellent new book by JR McNeill about parasites and humans in the New World: Mosquito Empire: Ecology and War in the Greater Caribbean. Here's a review and description: http://www.heyvalera.com/blog/archives/2281

[Doctor Science]

Thanks for the link to the McNeill book, ChrisJ! It's definitely going on my list.

[krista watkins]

stink bugs are the most nastiest insect ever, i cant believe those things even are on earth, they make me so sick because they stink so freaking bad.................... if anyone reads this i know y'all think the same things.
thanks.