Grammaticalization
In his survey of studies on language evolution, Bickerton (2005: 6) claims that grammatical structures, being biologically based, cannot be added, changed, or deleted. Looking at the literature on historical linguistics that has accumulated over the last centuries, such a view would seem to be somewhat naı̈ve.1 To take a simple example: Indo-European languages are historically derived from a common, hypothetical ancestor, Proto Indo-European. If Bickerton were right in his claim that grammatical structures cannot be changed then all Indo-European languages would have the same grammatical structure—that is, English would be structurally indistinguishable from Latin, Kurdish, or Hindi. Studies in grammaticalization show that change in grammatical structure is not only possible but is a predictable property of human languages and can be accounted for in a principled way. The present work is based on the application of grammaticalization theory, which relies on regularities in the change of linguistic forms and constructions, especially on the unidirectionality principle and the implications this principle has for the reconstruction of earlier language states.2
Grammaticalization is defined as the development from lexical to grammatical forms, and from grammatical to even more grammatical forms.3 Since the development of grammatical forms is not independent of the constructions to which they belong, the study of grammaticalization is in the same way concerned with constructions, and with even larger discourse segments (see Traugott and Heine 1991a, 1991b; Heine, Claudi, and Hünnemeyer 1991; Hopper and Traugott 1993; Bybee, Perkins, and Pagliuca 1994; Lehmann 1982; Heine 1997b; Kuteva 2001; Heine and Kuteva 2002a for details). In accordance with this definition, grammaticalization theory is concerned with the genesis and development of grammatical forms. Its primary goal is to describe how grammatical forms and constructions arise and develop through space and time, and to explain why they are structured the way they are. One main motivation for grammaticalization consists in using linguistic forms for meanings that are concrete, easily accessible, and/or clearly delineated to also express less concrete, less easily accessible and less clearly delineated meaning contents. To this end, lexical or less grammaticalized linguistic expressions are pressed into service for the expression of more grammatical functions.
That it is possible to push linguistic reconstruction back to earlier phases of linguistic evolution, that is, to phases where human language or languages can be assumed to have been different in structure from what we find today has been hypothesized in “Questions and approaches” (see also Heine and Kuteva 2002b; Smith 2006).
1 Presumably Bickerton’s notion of ‘‘grammatical structure’’ is not the same as the one commonly used in linguistic description. We are ignoring here the assumption that grammatical structure is biologically determined—an issue that is also not uncontroversial.
2 For a critical assessment of this theory, see “Assumptions”.
3 For a fairly comprehensive list of definitions that have been proposed for grammaticalization, see Campbell and Janda (2001).
