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1. Speech and language disorders and evolution

Theodosius Dobzhansky (1937), Paul Nurse (2020), and many others, propose that evolution is crucial to any understanding of how biology works. Robert Berwick and Noam Chomsky (2019) propose that this includes language and that “there must have been many steps in the evolution”. I take this further, and propose that this evolution must have included speech and that speech and language disorders are characteristically with respect to particular steps in this evolution. This removes any need for ‘phenotypes’ of disorder, as suggested by Lawrence Shriberg et al (2005) and others in the same tradition. Halving the ontology of disorder, as this does, it is a conceptual advantage.

This evolution must have proceeded in two ways, one giving the sounds, the other giving meaning, Both aspects are structured in ways that seem quite unlike the communication system of any other species. This is to say that speech and language are generated by highly specific procedures. And these procedures apply to all natural languages and in all contexts – reading, writing, talking, listening, and, crucially, imagining. They are universal. This universality is exampled in two sorts of characteristic alternation, in speech between vowels and consonants, and in language between ‘content words’ like baby and live and words with no meaning other than in relation to a structure – like that in: “I think that the baby is alive.” These universals are genomic, part of what makes us human. They consittute what is known as ‘Universal Grammar’ or UG.

For each step there must have been an advantage, or it would not have diffused across the population. The advantage may have been in relation to physical survival or for planning, plotting, grooming, befriending, sympathising, romancing or self promotion. Eventually, the various elements of the capacity we know as speech and language diffused across the population, coming to define all surviving inheritors, providing the wherewithal for every joint venture from from a hunt to a start up. Whether the issue was how to understand a broken twig or a false financial statement, “I think you might be mistaken” became reliably understandable, with life or fortune depending on the accuracy of the understanding.

My proposal here is agnostic about the timing and tempo of the steps. Each may have taken thousands, tens of thousands, or hundreds of thousands of years. But the last evolutionary step is likely to have been taken between the divergence between modern humans and Neanderthals around 650,000 years ago and must have been taken before the last major diaspora from Africa about 70,000 years ago. Neanderthal humans may have been able talk, but not as well as modern humans and without our species-specific characteristic of being able to agree about what things mean and argue about any differences of opinion over this.

Significantly, some claims to the contrary notwithstanding, it is generally agreed that there is nothing like a proto-language spoken by any modern, adult, human population. We are all ‘anatomically modern humans’ or ‘homo sapiens’ (‘wise man’ – since Latin did not have a word for ‘human’) or just ‘modern humans’. .

In all cases, the evolutionary steps I am postulating must have proceeded much slower than it takes for a modern, fully-developed language to develop a new system or lose an old one. I am thus assuming that the ‘Proto-Indo-European’, as it is known, spoken somewhere near the Black Sea perhaps 6,000 years ago, was already a fully developed modern language, before it started developing into the languages of Europe, Northern India, and the ancient Middle East. There are thus two orders of time, one for language, the other for languages.

On the assumption of a constant mutational rate for evolution, it was calculated that the last common ancestors of modern humans and chimpanzees lived about six or seven million years ago. But there is new evidence from Søren Besenbacher and colleagues (2019) that thia divergence was actually about  10 million years ago. David Reich (2018) takes the evidence to show that this divergence was like a long goodbye. But this sets a limit for the the time scale over which humans have evolved larger brains, flatter, more vertical faces, a highly-doomed forehead without craggy eyebrows, a smooth top of the skull, longer legs and feet, differently articulated hands and arms, smaller teeth, and crucially a deeper, more pointed chin, a larger tongue, a relatively long distance between the larynx and the lips and a larger nasal cavity. I am not saying anything about how the self-evidently cognitive event of speech and language connected up with any of the physical changes. We just have to note that these two sorts of change were in one species, and the changes in the head and neck favoured the production of the range of vowels which characterise all human languages. But while the capacity for speech and language clearly distinguishes humans from any other animal, and mostly develops naturally without any active intervention, this is obviously not the case for all.

My proposed sequence, outlined in A research proposal, unfolded within a population in the process of becoming human. As humans became more conscious of themselves, they reacted more strongly to the effects of the steps as they occurred. Very occasionally cetaceans, primates, and canids, display or invite empathy with humans. But humans display such consciousness every day, not as occasional, one-to-one exchanges. And human consciousness is recursive. We are aware not only of the consciousness of others, but of their consciousness of our consciousness. And so on. This recursive consciousness made the evolution of speech and language quite unlike that of most, if not all, non-human evolutions.

The notion of UG is vigorously challenged by authors like Salikoko Mufwene (2013). I uphold the idea because it seems to me to offer the only way of explaining both the now very substantial evidence of language acquisition, but also some otherwise very surprising phenomena that seem to characterise all languages like the fact that sometimes the main message is in what is not actually said, as by the slogan “Me too” or the marriage vow “I do” or the instruction  “Just don’t”. These all exemplify what linguists call ‘elipsis’.

The proposals here are made in what is known as a ‘generative’ framework, as originally formulated by Noam Chomsky in the 1950s. By my proposal here, the whole process of speech and language evolution has been from a step-wise development of the surprisingly complex and subtle process of putting two words together, knowing what they mean separately and together.

It is sometimes thought that the main focus in the analysis of child speech should be on what they most often get wrong. But that does not answer the questions: Why do children get wrong what they do, not just individually, but generally?

The first step to an answer, I propose, is to consider what learners HAVE to attend to, inc luding the very complex phenomenon of elipsis. The learner of English must be attending to this in order to progress to being a competent native speaker.