Language from gesture

by Andrew Carstairs-McCarthy

FROM HAND TO MOUTH, by Michael C. Corballis (Princeton University Press. $???)

How did human language originate? Most linguists think that question is futile, because vowels and consonants do not fossilise. However, Michael Corballis, an Auckland University psychologist, is not so pessimistic He approaches the topic mainly as an expert on the brain, but he is well informed, too, about biological anthropology (the study of human evolution since the human-chimpanzee split, about five or six million years ago). His style is admirably unintimidating. He seems to know just when his technical content needs enlivening with some dry wit. As a bonus for New Zealanders, this wit is often at the expense of Australians. I can recommend this book to anyone who wants a readable and up-to-date account of language evolution research—but with qualifications.

Corballis thinks that the original primary medium of linguistic communication was gesture, and that ‘autonomous speech’ may have arisen, as an invention, only as recently as 50,000 years ago, shortly before the cultural explosion evidenced by the cave paintings of the Pyrenees and the simultaneous increase in the sophistication of stone tools. Only when speech took over could people use language conveniently to communicate about what they were doing with their hands, and hence learn quickly to make more sophisticated things. But this view is controversial, as he admits. I will mention two problems.

The first problem has to do with Corballis’s explanation for why right-handedness predominates. The left hemisphere of the brain controls the right half of the body, and vice versa. In right-handed people, therefore, it is the left hemisphere that controls the dominant hand. In most people, the left hemisphere is also the location of the brain regions that control speech. Gestural-origin protagonists have tended to use right-handedness to explain this: if our gesturing ancestors used their right hands predominantly, then, when language became predominantly vocal, the corresponding left-brain bias was carried over to speech. However, Corballis turns this cause-effect relationship on its head. There is good evidence for left-hemisphere control of vocalisation in many vertebrates, including frogs and birds as well as mammals. On the other hand, a strong left-hemisphere bias in hand control is evident only in humans. He argues, therefore, that humans did not become predominantly right-handed until speech began to take over from gesture, through a transfer to the ‘old’ predominant medium, the hands, of a bias already established for the ‘new’ medium, the voice. But it seems strange that the voice should exert so much influence over the hands, extending even to manipulations that have nothing to do with language, just when the linguistic role of the hands was being severely diminished. Corballis’s scenario would seem to fit more easily an alternative world in which humans exhibit no greater right-hand bias than apes do.

The second and more serious problem involves Corballis’s view that, although language has a biological basis, the use of speech as a medium for it was a cultural invention, much like writing or piano-playing. Corballis rightly identifies ‘recursion’ as a central characteristic of language—that is, the possibility of nesting sentences inside sentences, as indicated by the brackets in [John thinks [Mary knows [that he went out with Belinda last week]]]. But, as all linguists will insist, the complexity of syntax involves much more than recursion. Consider the two questions When did John say he hurt himself? and When did John say how he hurt himself? The first (without how) is ambigous it can be interpreted is as asking about the timing of either John’s injury or John’s report about it. The second (with how) is unambigous: it can only relate to the timing of John’s report, not of the injury. Is the ambiguity contrast between such questions part of language as a cultural phenomenon, that children learn by trial and error much as they learn other cultural practices such as writing and piano-playing? If it is, we will expect to find that young children make mistakes about it, just as they sometimes say bringed or brang instead of brought. But it turns out that they don’t; that is, young children never misinterpret the second question as being about the timing of the injury. The contrast must therefore be due not to culture but to biology—the biological endowment that (Corballis agrees) children bring with them to the task of acquiring language.

Linguists offer a technical explanation for the difference between the two questions in terms of constraints on the syntactic ‘movement’ of question-words such as when to the first position in the sentence—a feature of English but not of all languages. So, if the biological basis of language was laid down at a time when language was predominantly gestural (as Corballis claims), ‘movement’ constraints must have been laid down then too. But this is unlikely, because syntactic movements are especially a feature of languages in which all words are unavoidably uttered in a temporal sequence—that is, spoken languages. In gestural languages, such as the contemporary sign languages of the deaf, the tyranny of temporal sequencing is mitigated, because many signs can be made simultaneously (for example, signs for an action and for the person or thing performing or affected by it). So the difference in interpretation between those two questions is more likely to have acquired its biological underpinning at a time when language was predominantly spoken. That in turn pushes ‘autonomous speech’ back to well before 50,000 years ago, because 50,000 years is too short a time for such biological underpinnings to become established in a species as long-lived as humans.

I disagree, then, with Corballis’s central proposal. But potential readers should not let that put them off! The origin of language is one of the most contentious issues in all science. Corballis’s ideas are thought-provoking and engagingly presented, and deserve at least as much attention as their rivals in the marketplace.