Africa: Reproductive Strategies and the Value of Gold

Partway through John Reader’s Africa: A Biography of a Continent I’ve been disappointed in some superficial or misleading sections about science and economics. But the book is definitely worth a read if you have broad interests and I wanted to post about two topics that caught my interest.

Reproductive Strategies:

Evolutionary biologists have grouped the ways of life which natural selection has favoured during the course of evolution into two broad categories: r- and K-strategies.

Organisms [with] r-strategiesare opportunists, existing in minimal numbers for much of the time but able to increase rapidly and move on to colonize other regions when conditions permit…

K-strategists … occupy more predictable environments … [and] seek equilibrium and stability. (pp. 129-130)

It’s pretty easy to sort species into one group or the other, though again these are just broad groups.1 The quintessential r-strategists are most insects, rodents, and weeds. Whales and elephants on the other hand are standard K-strategists: very few offspring, late reproductive age, long lifespan. Interestingly the tsetse fly is actually a K-strategist as it only lays a few eggs in its lifetime and lays them one at a time, which makes eradication very difficult (241).

More interestingly, humans look a lot like K-strategists in terms of our physical characteristics since we are large,  mature slowly, invest a lot in our few children, and so forth. But “the evidence of human population growth patterns, modern as well as prehistoric, indicates that humans are supreme opportunists who survive in numbers some way below the carrying capacity of the environment for much of the time, but whose growth rate potential [and adaptability] enables them to multiply rapidly when circumstances permit.” (131) For example, only a few hundred humans left Africa and look how that turned out.

The Value of Gold

A nice reminder about the cultural determination of value, and also about the forces of supply and demand:

Though locally abundant, [gold] served no practical, ritual, or even ornamental purpose in the affairs of people in sub-Saharan Africa until demand from the north reached the region, and even then it remained solely an item of trade…a source from the early fourteenth century reports that copper was exchanged for two-thirds its weight in gold. (287)

Anyway, the book is full of these kinds of topical digressions and he’s quite good about integrating them later in the narrative as well. Pick it up next time you want to read 700 pages of interesting factoids loosely related to the history of Africa.

  1. And interestingly it looks like this paradigm fell out of favor among evolutionary biologists in the early 90’s while the book was published in ’97, which confirms my suspicions about the writer’s scientific chops. []

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