The evolutionary origins of syntax: Optimization of the mental lexicon yields syntax for free

Abstract

This paper presents an account of the evolution of human language by natural selection that focuses on the evolution of the lexicon. It will be argued that the expansion of the lexicon as a knowledge representation system requires it to be structured – and that Normalization Theory (Codd, 1970, 1983) provides the theoretical tools to understand these linguistic structures (De Vos, 2008). By developing an evolutionary narrative around the acquisition of the lexicon, I will show that the same mechanisms used in lexicon organization are critical for recursion (De Vos, 2008). In other words, the communicative capacities imparted by natural language syntax may not have been the original locus of natural selection (Pinker and Jackendoff, 2005) but developed as a side-effect of lexical development. Furthermore, the framework is precise enough to give predictions of the types of syntactic constructions that might have been used at each stage. It predicts gradual evolution of the language faculty but where a number of small changes in the lexicon suddenly allow a florescence of complex linguistic forms. As such, this paper argues for an intermediate position between the gradualist and saltationist positions on language evolution.