Processes of Language Shift

The predominant language spoken in a certain region in the world will most probably have changed several times since the settlement of the first humans using verbal communication.

The birth of a new language is a slow process that usually includes several successive minor processes that spread throughout the population over the course of millennia (Renfrew 1987), until eventually the language has diverged enough from the original language as for them to be mutually unintelligible. These are often considered random processes, analogous to genetic drift, which may include the invention of new words—e.g., for innovations—, acquisition of loanwords from other languages in contact, phonetic changes—e.g., the use of occlusive sounds (p, t, k) in Latin, Greek and Sanskrit, as opposed to the fricative sounds (f, th, h) used in the Germanic languages, all of which share the same Indo-European origin (Lightfood 1999)—and ultimately the apparition of new grammatical forms (Ren­frew 1987). A millennium would seem to be the minimum time span for this linguistic divergence to yield the birth of a new language (Cavalli-Sforza et al. 1994). Historical well known examples of language birth are the Romance lan­guages from Latin, or the Indo-European languages from a probable common origin.

The other process of language shift, the displacement of the local language by a foreign one that becomes the new prominent language in the region, once started is usually a much faster process (McMahon 1994), and it can take place in as short a time as a single generation (Krauss 1992). However, as mentioned above, language is often strongly related with ethnicity and not so readily assimilated as other changes.

The first mechanism, denoted demography/subsistence, would entail the arrival of new population into the territory, bearing some new exploitative technology that would allow them to subsist at significantly higher densities, thus outnumbering the local population and prompting their language to be the new dominant one. The spread of farming in Europe is known to have mostly taken place in such a way, and it may have well introduced their language into Europe alongside the farming technologies. Renfrew (1987) theorized that this language might be the Proto-Indo-European language from which most European and several Asian lan­guages aroused. This theory has recently been supported by the results from a study that applied computational methods derived from evolutionary biology to infer an Indo-European language tree, as well as a chronology of the divergence times for every linguistic branch (Gray and Atkinson 2003). Their analysis estimated the initial Indo-European divergence to have taken place about 7800-9800 years BP, consistent with the initial spread of agriculture from Anatolia around 8000­9500 years BP (Gray and Atkinson 2003). Therefore, the spread of the Proto-Indo-European language into Europe would be an example of the demography/subsistence mechanism, and so would be some modern processes such as the spread of English (and its speakers) into Australia or North America—this last one including the use of the force of arms (Renfrew 1987).

The second mechanism, elite dominance, implies as well the arrival of foreign population but in this case, rather than introducing a new technology, the newcomers would be a reduced group with military superiority who would undertake the ruling of the region. This would lead to a period of bilingualism and the language of the elite may eventually become the dominant language.

Finally, the third main mechanism leading to language displacement described by Renfrew (1987) was as a consequence of system collapse. In this case the language displacement would be the consequence of the collapse of a rapidly growing, highly specialized society whose central authority would not be able to maintain control in case of environmental adversities. The collapse could entail the exodus of local people as well as the loss of the control over the frontiers, thus losing terrain (politically and linguistically) to neighbouring better structured societies. And precisely for this reason, Cavalli-Sforza et al. (1994) englobed this mechanism and the elite dominance under a single denomination: conquest by a minority. The collapse of a previous system may have been the mechanism that yielded the Nahuatl language to become dominant with the Aztecs in Mexico (Renfrew 1987).

Besides these mechanisms, Cavalli-Sforza et al. (1994) additionally noted that language displacement processes may also be observed without the need of pop­ulation movements introducing a new language. In this case, the new language would be acquired as a result of continuous contact between neighbouring lan­guages, with one of them becoming the new main language near the border—we may call it neighbouring acquisition.

Below we present a language competition model devised to predict the evolution of the number of speakers when an external language is displacing the native one. In the model, we are interested especially in language displacement processes which do not imply large movements of people. Therefore, this would mostly correspond to cases of language displacement due to the mechanisms of elite dominance or neighbouring acquisition, or a combination of both. In the next section we consider non-spatial models of such processes. In Sect. 7.4 we gener­alize them into spatial models (i.e., models of moving linguistic borders) to describe the case of neighbouring acquisition of a language. They can be also useful to describe elite dominance, but in this case we note that (i) there is usually a military conquest first, after which the language substitution process takes place; (ii) the new language spreads possibly from one or several geographic centres of political power, rather than from an outside adjacent area.

7.3