Introduction

At least three unique properties distinguish language from other systems of animal communication: unlimited semantic scope, freedom from control by identifiable external stimuli (displaced reference), and transduction into alternative perceptuomotor modalities (writing, fingerspelling). All three properties, it will be argued, depend on dissociating phonetic form from semantic function. Such a dissociation arose with the emergence of vocal imitation, a necessary condition of the protolanguage that evolved when our hominid ancestors chanced on ‘the particulate principle of self-diversifying systems’ (Abler 1989). This is a physical principle to which all natural systems that, in Humboldt's (1836/1972: 70) famous phrase, ‘make infinite use of finite means’ (physics, chemistry, genetics, language) necessarily conform. In such systems, discrete units from a finite set of meaningless elements (e.g. atoms, chemical bases, phonetic segments) are repeatedly sampled, permuted and combined to yield larger units (e.g. molecules, genes, words) that are higher in a hierarchy and both different and more diverse in structure and function than their constituents.

The particulate principle rationalises both the hierarchical structure of language and the discrete combinatorial mechanisms on which the hierarchy is raised. The principle has many implications for the evolution of language. For example, it casts doubt on the likely communicative scope of any prelinguistic symbolic system, limited to a purely analog representation of the world (e.g. Donald 1998). And the necessity for hierarchical organisation discourages the notion that syntax might have emerged before the combinatorial mechanisms of phonology were well established (Bickerton 1998: 344).