‘Extracting phyletic information from ontogeny’

The title of this section – a phrase borrowed from Stephen Jay Gould (1977: 212) – nicely captures what the acquisition window on language evolution is about. On Gould's account, the idea that a parallel exists between the stages of ontogeny and phylogeny is an ancient one. This idea has, in his view, been among the most important themes in the history of biology since Aristotle's time. It has also formed the basis of a range of theories on the evolution of language, a phenomenon about which no direct evidence exists. In response to the lack of fossil evidence, Kathleen Gibson, for instance, maintains that

Jim Hurford (2012: 590) goes even further when he states that ‘language acquisition [is] the most promising guide to what happened in language evolution’. He accordingly bases his gradualist theory of the origin of syntax primarily on evidence derived from language acquisition.

In preceding chapters, we have already looked briefly at inferences drawn by two scholars about language evolution from data about language acquisition. Thus, Chapter 5 deals with early work by Derek Bickerton (1990: 110ff.) in which he portrays the language of children under two as a ‘linguistic fossil’ that provides evidence for the properties of protolanguage as a stage in the evolution of language. In his words:

Chapter 7, in turn, considers cursorily Dean Falk's (2009: 106–8) use of the acquisition window. She holds, it may be recalled, that the way in which modern motherese aids contemporary babies in acquiring their language recapitulates to some extent the way in which prehistoric motherese facilitated the emergence of protolanguage and language.

The theories of language evolution proposed by Gibson, Hurford, Bickerton and Falk by no means exhaust the stock of those that attempt to extract phyletic information from linguistic ontogeny.