Introduction

Grammaticization is the diachronic process by which:

• lexical morphemes in a language, such as nouns and verbs, develop over time into grammatical morphemes; or

• morphemes less grammatical in nature, such as auxiliaries, develop into ones more grammatical, such as tense or aspect markers (Bybee et al. 1994).

Thus any given grammatical item, even viewed synchronically, is understood to have an evolutionary history. The development of grammar may be traced along grammaticization pathways, with vestiges of each stage often remaining in the current grammar (Hopper 1991; Bybee et al. 1994), so that even synchronically, lexical and grammatical items that share similar form can be shown to be related. Grammaticization is thought to be a universal process; this is how grammar develops. Bybee et al. claim that this process is regular and has predictable evidence, found in the two broad categories of phonology and semantics. Semantic generalization occurs as the more lexical morpheme loses some of its specificity and, usually along with a particular construction it is found within, can be more broadly applied. Certain components of the meaning are lost when this generalization takes place. Regarding phonological change, grammaticizing elements and the constructions they occur in tend to undergo phonological reduction at a faster rate than lexical elements not involved in grammaticization.

The ultimate source of grammaticized forms in languages is understood to be lexical. Most commonly, the source categories are nouns and verbs. Thus, the origins of numerous grammatical elements, at least for spoken languages, are former lexical items.