Kensy Cooperrider writes: ome metaphors end up forgotten by all but the most dedicated historians, while others lead long, productive lives. It’s only a select few, though, that become so entwined with how we understand the world that we barely even recognize them as metaphors, seeing them instead as something real. Of course, why some fizzle and others flourish can be tricky to account for, but their career in science provides some clues.

Metaphors, as we all by now know, aren’t just ornamental linguistic flourishes — they’re basic building blocks of everyday reasoning. And they’re at their most potent when they recast a difficult-to-understand phenomenon as something familiar: The brain becomes a computer; the atom, a tiny solar system; space-time, a fabric. Metaphors that tap into something familiar are the ones that generally gain traction.

Charles Darwin gave us both kinds, big winners and total flops. Natural selection, his best-known metaphor, is still a fixture of evolutionary biology. Though it’s not always recognized as a metaphor today, that’s exactly what it was to Darwin and his contemporaries. After all, evolution was a foreign and unwieldy concept. So Darwin set out to make it accessible by comparing it to a method employed in farmyards around the world.

For years, Darwin — a fancy pigeon breeder — obsessed over what he called artificial selection, what cattle-breeders, gardeners, and crop-growers did to create new varieties of plant and animal: allowing just the ones with desirable traits to reproduce. Darwin’s first-hand experience with breeding set the stage for his now-famous metaphoric leap. [Continue reading…]