Published online by Cambridge University Press: 05 November 2012
In the last chapter, we derived the notion of the ‘language-ready brain’, which Arbib (2005b: 22) saw as providing ‘the capacity to acquire and use language’, and supporting ‘basic forms of gestural and vocal communication … but not … rich syntax and compositional semantics’. In this chapter, we shall ask how clearly we can define and describe the product of that language-ready brain, which we might call protolanguage. Furthermore, once protolanguage had developed, how did it subsequently become more complex, to give us the variation and structure characteristic of modern human languages? These questions of structural complexity connect to issues of motivation as well as mechanism. We have argued for the admissibility of arguments based on natural selection in the evolution of the capacity for language; but should this extend to accepting adaptive accounts of the subsequent increase in linguistic complexity? Invoking natural selection for genetic specification of the brain or physical systems controlling language in general is one thing, but claiming direct genetic control of individual constructions or concrete elements of a language would be something else again. On the other hand, if natural selection is not involved in the transition from protolanguage to language, then what does explain that development? Are the arguments about motivations for enhanced structure in language affected or shaped by the nature of protolanguage itself? And if so, how confident can we be in our assertions about protolanguage and hence about the mechanisms for increasing linguistic complexity? Even if we were to conclude that learning rather than evolution is the major factor shaping the development of modern languages, which would therefore fall within the domain of cultural rather than biological evolution, is there any capacity for feedback from those learning mechanisms to the genetic level, or are these completely insulated from one another? Indeed, is it reasonable to distinguish between biological and cultural evolution at all?