Language change has been described as an unintended effect of language in use (Keller, On language change: The invisible hand in language, Routledge, 1994). In this view, change results from the way individuals use their language; the challenge is thus to explain change and its properties in terms of factors operating on the individual level, and population dynamics. An intriguing example of such a phenomenon is the finding that language change shows some highly regular tendencies. This has recently received considerable attention in the literature (Bybee et al., Why small children cannot change language on their own: Suggestions from the English past tense, John Benjamins, 1994; Heine and Kuteva, World lexicon of grammaticalization, Cambridge University Press, 2002; Traugott and Dasher, Regularity in semantic change, Cambridge University Press, 2002; Hopper and Traugott, Grammaticalization, CambridgeUniversity Press, 2003). In unrelated languages, similar words often change in similar ways, along similar “trajectories” of development. This phenomenon is called “unidirectionality”, and it is an important part of processes of grammaticalization, items changing from a lexical meaning to a grammatical function. It has been claimed that around 90–99% of all processes of grammaticalization are unidirectional (Haspelmath, Linguistics 37: 1043–1068, 1999).
This article explores several mechanisms that may lead to language change, and examines whether they may be responsible for unidirectionality. We use a cultural evolutionary computational model with which the effects of individual behavior on the group level can be measured. By using this approach, regularities in semantic change can be explained in terms of very basic mechanisms and aspects of language use such as the frequency with which particular linguistic items are used. One example is that frequency differences by themselves are a strong enough force for causing unidirectionality. We argue that adopting a cultural evolutionary approach may be useful in the study of language change.
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