I’m not a biologist, and even if I were I wouldn’t do free coaching. There are some basic misconceptions, though, so common as to be worth trying to correct on a site like this. Here’s a reader:

Derb — Would you be able to explain to a layman such as me how the human race could possibly still be subject to the precepts of evolution? I was under the impression that “survival of the fittest,” i.e. random, slightly superior genetic attributes allowing a creature a better chance at reproduction, was the governing principle of evolution. In a civilized society do not the “unfit” produce as much or even more children than the “fit?” Does not “survival of the fittest” only have free reign in a state of nature?

[Me] The misconception here, which also informs a lot of social-Darwinism twaddle, hinges on the word “fit.” We all know what it means in common usage, with connotations like healthy, strong, aggressive, etc. The phrase “survival of the fittest” therefore conjures up mental images of vigorous struggle, Nietzschean Blond Beasts lopping the heads off weaker specimens with broadaxes.

In biology, however, “fitness” is a term of art, a measure of how well an organism is adapted to its environment. Reproductive success is a pretty good measure of fitness, in this term-of-art sense. Thus if, as my reader seems to believe, dumb people have more kids than smart ones, then dumb people are fitter (in the biological sense) than smart people, by definition. They are better adapted to their environment.

You might think that smart people are superior in some way to dumb people, but Ma Nature doesn’t agree with you. The only “superiority” She acknowledges is reproductive success. She also doesn’t insist that every species, in every environment, get smarter, faster, bigger, and stronger. If the demands of fitness decree that dumber, slower, smaller, and weaker bring reproductive success, She’s fine with it. She’s even fine with it if the fool species goes extinct … as practically all species do sooner or later.

Take the humble butterfly, not really an emblem of violent struggle for supremacy. Yet butterflies have terrific fitness. They’ve been around for 60 million years! The tiger, by contrast, a much more struggly sort of organism, has been around less than two million years … and is on the verge of extinction. Butteflies are by no means the extreme. The real fitness world champions are deeply un-struggly organisms like the sea cucumber — 400 million years and counting.

So if you want to get a conceptual handle on “fitness” as biologists understand it, forget about Blond Beasts. Think sea cucumbers.