8 - Big bang or cumulative creep? Saltation versus gradual, adaptive evolution

Summary

Overview

Since Chapter 4 was entitled ‘Who, where and when?’, we should really call the current chapter ‘How and why?’ In Chapters 5–7, we have built up a picture of the physical structures which enable language; but we have not yet got to grips with how and why those aspects of modern human vocal tracts, brains and genes developed in the first place. There are two central questions here, which will occupy us through this chapter, and continue to underlie some of the discussion in Chapter 9. First, did the underpinnings of language emerge as a single package, perhaps as the result of one monumental genetic mutation, the final step in a series of predisposing changes which took modern humans over an essential cognitive threshold, creating a new species in the process? Or are we dealing with a mosaic of interacting but essentially independent processes, following their own evolutionary trajectories but giving the impression in retrospect of working towards a common goal because they are all improving the fit of individuals to their environmental niche? Second, did the structures and systems we use linguistically emerge precisely to allow us to become linguistic animals, or are they by-products of different motivations and evolutionary paths, which fortuitously turn out to provide us with the capability for language as a kind of unexpected bonus? In short, this chapter will be concerned with whether the structures underlying language emerged punctually or gradually and whether they evolved specifically for language or language is a happy accident.