1. Speech and language: Evolution

Impairment

Where there are problems with respect to a child’s speech and language it makes sense to investigate this as just one of billions of cases of children learning to talk successfully and without help and how this extraordinary ability evolved.

If this had been an experiment, the numbers would make this the largest experiment in the history of science. It should not be said that there is any shortage of data.

The end-state

All learners of any language can expect to converge on a single grammar, and, in the case of English, agree that:

• “You believe that it’s true?” and “You believe it’s true?” mean the same thing.

• “The rabbit is ready to eat” is ambiguous.

• “Mightn’t the ball that won the match that the bookie keeps talking about have been being examined by the umpire?” is meaningful (even if it doesn’t exactly roll off the tongue).

Some children will hear examples of all of these. But others may not. How does the convergence happen? By my hypothesis, speech and language must have evolved by a particular and necessary sequence of steps. The big question is: What exactly did these steps consist of?

Starting from square one

This process has to have begun with the simplest possible forms. Although development does not always recapitulate evolution, there is often a relation. And in this case I propose, on rather obvious evidence, that there is a very strong relation. There is another big question, on which linguists differ sharply, about what comes next. So there are different analyses of all three of the bulleted sentences above.

But for one (large) group of linguists they all contain elements which are not pronounced. These unpronounced elements are critical for the way these sentences are understood. But if that is so, there is yet another big question: When and how do children learn about the unpronounced elements?

I believe, as do many linguists who follow a suggestion first made by Noam Chomsky, that humans have evolved a mental structure which makes it possible for learners, even very small learners, to ‘hear’ elements which are not actually pronounced. In all cultures, this seemingly extraordinary feat is accomplished effortlessly and reliably before the age of ten.

This mental structure makes human beings different from any other animal.

The natural history

First there is a period during which the child says only single words, for a period maybe only one word. And it may be very hard to understand. Then, typically sometime between 18 and 21 months, words start to be put together. Then between a week and two months after saying something like “Duck bath”, the child either asks a question like “Where duck?” or answers a question by an adult like “Where’s your duck?”. And so on, step by step. During the last five years of this period children learn how to say words of four and five syllables like calculator and hippopotamus and the subtleties of what are known as ‘control verbs’, by which “I persuaded her to be good” means that it will be her being good, whereas “I promised her to be good” means that I am the one who has to be good.

A guiding idea

The natural history, the linguistics, and what this says about the possible course of evolution are the main topic of my research.

The guiding idea here is to better understand the commonest pathologies, what are known as ‘Speech Sound Disorders’, Specific Language Impairment, stammering, Autistic Spectrum Disorder, and Central Auditory Processing Disorder, and their impacts on literacy.

By the hypothesis on which I am currently working, all of these pathologies can best be understood as failures with respect to an evolution over two million or more years. The failures are either by non-activation or by activation at the wrong point or in the wrong way. They are mostly marginal. But some need specialised help to fix. The greatest developmental vulnerabilities are with respect to the most recently evolved characters, on which fixation is least robust.