The less often a word is said, the faster it will change over time, whereas more-often uttered words are resistant to change. In this week’s Nature, two groups publish analyses of this trend, which quantify it and compare it with biological evolution. The idea that aspects of culture might ‘evolve’ in in a similar way as biological organisms dates back to Darwin himself. The notion was given a big push forwards in 1976, when Richard Dawkins introduced the concept of ‘memes’ — aspects of culture or fashion that “propagate themselves … by leaping from brain to brain”.
“There is this general idea that culture evolves, but it is more of a metaphor than something that has teeth — that obeys precise mathematical rules,” says Erez Lieberman, a specialist in evolutionary maths at Harvard University. Lieberman was struck by this idea when he learned that the ten most common verbs in English (be, have, do, go, say, can, will, see, take, get) are all irregular. Instead of their past tenses ending in ‘-ed’, as do 97% of English verbs, they take the peculiar forms of was, had, did, went, said, could, would, saw, took and got. Researchers suppose that this is because often-used irregulars are easy to remember and get right. Seldom-used irregulars, on the other hand, are more likely to be forgotten, so speakers often mistakenly apply the ‘-ed’ rule. The most commonly used word that they found this happened to was the verb ‘to help’ – the past tense used to be ‘holp’, but is now ‘helped’.