If you were a cowboy and you wanted your horse to giddyup, you might dig your spurs into its flank. Upon arriving at the next town, if you wanted your steed to slow down, you’d pull on the reins. While relatively few people are cowboys today, the language still retains their experiences: Marketers hope to “spur” sales; talk too much in the quiet car and you’ll be asked to “rein in” your speaking.
As Penn linguist Mark Liberman notes in a clever little post at Language Log, most words are, in a sense, “obsolete expressions,” like pen a letter or dial a phone number. Rarely is a letter literally penned; few are the numbers physically dialed. But the expressions hold.
The patterning of expressions tends to come in two flavors, he contends: “An expression for a concrete object is used to refer to an activity in which that object is central,” he says, in a phenomenon called metonymy, and then that usage “may be extended to similar activities where the original object is not involved” — better known as a metaphor. From there, the extended usage can keep extending, long after the everyday object and people’s interactions with it have faded from everyday life. That’s why, he says, pen is still to write, dial is to enter a sequence of numbers, telegraph is to give a premature indication.
This is because, as linguists will tell you and dictionaries won’t, language is more an organism than a machine, and what some might call decay is actually growth, or more neutrally, change. As Columbia linguist John McWhorter notes in his book on the subject, “One of the hardest notions for a human being to shake is that a language is something that is, when it is actually something always becoming.”
While “brother” has held its meaning for 7,000 years, dating back to, they say, the proto-Indo-European that English descended from, words are constantly engaging in semantic drift. The problem, of course, is time scale: words reincarnate into new meanings at a slower pace than humans tend to live, so we get the impression that people have always talked this way — when in fact, as these examples show, they haven’t. Like, literally.