The authors turn generative grammar on its head by asserting that language evolves to fit the brain rather than vice-versa. It is an appealing idea, but how literally are we to take this word evolution? How many features of biological evolution are visible in linguistic change?
- Traits: Biological specimens are complex with a number of different traits. Languages too have many traits: pronunciation, grammar, and vocabulary being three obvious ones. Without different traits, there would be nothing to evolve.
- Variety: Neither biological individuals not linguistic utterances are identical. They have different combinations of traits, and this variety gives the process something to select, or at least drift.
- Lack of design: Evolutionary products seem so well adapted to their circumstances that many people assume they were designed, but they are the fruit of selection and drift. Language has many characteristics that seem to result from drift. Pronunciations, for example, can shift quite a bit in fairly short time spans. The Great Vowel Shift in English during the 1300s altered the way many vowels were generated without needing some great plan behind the change. Syntax too just seems to happen and vocabulary is just there. Even when a word is deliberately coined (e.g. television) some other term may come to dominate (e.g., TV in America and telly in Britain). Yet, there is something missing from this analysis. Biological evolution produces a great deal of non-viable individuals—monstrous birth defects, small handicaps that limit competitive effectiveness, etc. Biological evolution demands a brutal weeding, and there is nothing like it in language. If somebody misspeaks, the speaker may make an immediate correction or the listener can ask for a prompt clarification. Many writers and some speakers are so conscious of what they are saying that they make changes as they produce their utterance. Language as a whole has not been designed, but many instances of its use are deliberately fashioned. So along with its Darwinian drift there seems to be a touch of Lamarckian striving as well.
- Genetic material: Evolution follows a double track, changing both organisms and genetic information. Survival of the gene depends on survival of the organism, while the traits of the organism depends on the genetic information. The physical traits are abstractions whose existence depends on the DNA molecule. There is, however, no enduring linguistic molecule. Some people have theorized about memes, but the metaphorical nature of the meme becomes apparent as soon as you look for its lasting material. Meaning is not dependent on phonemes in the way traits depend on genes. Language takes a physical form (sound waves, hand shapes, written alphabets) but the form is generated at the same time the utterance is generated and fades just as quickly. The carrier of language is not the physical form of the utterance, but the whole human being. We are the linguistic material, and we can change a great deal during our lifetimes. So our speech shows another Lamarckian aspect, acquired changes are passed along.
- Mixing genetic material: Most organisms are asexual, but all organisms have a means (sex, conjugating, etc.) of mixing up the genetic information. Without that mixing, organisms would simply be clones of one another and eventually become maladapted and then extinct. Likewise, to develop a healthy language, language users must mix, pickup up words, forms, and even topics from one another. Deaf children have always produced a few “home signs” that can be used to signal basic needs, but it is only when deaf children come together that the signs turn into a real language, something enabling people to explore a particular topic. When languages stop mixing, as can happen in religious, scholarly, and legal traditions, they eventually become maladaptive, but if they continue to mix, they can thrive in perpetuity.
So it seems that in some ways language change does resemble biological evolution, but not in all ways. The key difference appears to be that biological evolution has no greater goal, while language users have goals that can lead them to choose their words carefully and to learn new ways of speaking. Linguistic evolution is neither as brutal nor as aimless as the biological kind.