The consequences of talking to strangers: Evolutionary corollaries of socio-cultural influences on linguistic form

We explore the proposal that the linguistic forms and structures employed by our earliest language-using ancestors might have been significantly different from those observed in the languages we are most familiar with today, not because of a biological difference between them and us, but because the communicative context in which they operated was fundamentally different from that of most modern humans. Languages that are used predominantly for esoteric (intra-group) communication tend to have features that are semantically and grammatically 'complex', while those used also (or even exclusively) for exoteric (inter-group) communication become 'simplified' towards rule-based regularity and semantic transparency. Drawing on a range of contemporary data, we propose a psycholinguistic explanation for why esotericity would promote such complexity, and argue that this is the natural default setting for human language. This being so, it should be taken into account when modelling the evolution of language, for some of the features that are normally viewed as fundamental - including the notion of fully developed underlying rule-based systematicity - may, in fact, be cultural add-ons. (c) 2005 Elsevier B.V. All rights reserved.