Language shift, bilingualism and the future of Britain's Celtic languages

Abstract

'Language shift' is the process whereby members of a community in which more than one language is spoken abandon their original vernacular language in favour of another. The historical shifts to English by Celtic language speakers of Britain and Ireland are particularly well-studied examples for which good census data exist for the most recent 100-120 years in many areas where Celtic languages were once the prevailing vernaculars. We model the dynamics of language shift as a competition process in which the numbers of speakers of each language (both monolingual and bilingual) vary as a function both of internal recruitment (as the net outcome of birth, death, immigration and emigration rates of native speakers), and of gains and losses owing to language shift. We examine two models: a basic model in which bilingualism is simply the transitional state for households moving between alternative monolingual states, and a diglossia model in which there is an additional demand for the endangered language as the preferred medium of communication in some restricted sociolinguistic domain, superimposed on the basic shift dynamics. Fitting our models to census data, we successfully reproduce the demographic trajectories of both languages over the past century. We estimate the rates of recruitment of new Scottish Gaelic speakers that would be required each year (for instance, through school education) to counteract the 'natural wastage' as households with one or more Gaelic speakers fail to transmit the language to the next generation informally, for different rates of loss during informal intergenerational transmission.

Figure 1.

Percentages of Gaelic speakers (mono- and bilingual) in Scotland in successive census years, 1891–2001. Data for civil parishes: 1891–1971 from Withers (1984, pp. 227–234); 1981 from Withers (1988, p. 40); 1991–2001 from General Register Office for Scotland (2005, table 3). Red, 75–100% Gaelic speaking; orange, 50–74.9% Gaelic speaking; yellow, 25–49.9% Gaelic speaking; white, less than 25% Gaelic speaking.

Figure 2.

Frequencies of the three sub-populations in the four Scottish Highland counties for the time period 1891–2010. Empirical data (solid lines) and predictions of model (5.1) under the assumptions c₃₁ = c₃₂ and c₁₃ = c₁₂ (dotted lines) and c₃₁ ≠ c₃₂ and c₁₃ ≠ c₁₂ (dashed lines) of the frequencies of Gaelic (black), bilingual (light grey) and English (grey) speakers in (a) Argyll, (b) Inverness, (c) Ross and Cromarty and (d) Sutherland over time.

Figure 3.

Empirical and projected frequencies of the three sub-populations in Wales for the time period 1901–2001. Empirical data (solid lines) and predictions of model (5.1) under the assumptions c₃₁ = c₃₂ and c₁₃ = c₁₂ (dotted lines) and c₃₁ ≠ c₃₂ and c₁₃ ≠ c₁₂ (dashed lines) of the frequencies of Welsh (black), bilingual (light grey) and English (grey) speakers. (a) Prediction of model (5.1) with parameters given in table 1 (bottom four rows) and (b) prediction of model (5.2) with the same c-values and w₁ = 0.005 and w₃ = 0 for the time period 1901–1971 and w₁ = 0.01 and w₃ = 0 for the time period 1971–2001.

Figure 4.

Empirical and projected frequencies of the three sub-populations in the Scottish Highlands for the time period 1901–2030 with assumed intervention after 2009. Empirical data (solid lines) and predictions of model (5.1) until 2009 and model (5.2) after 2009 (dashed lines) of the frequencies of Gaelic (black), bilingual (light grey) and English (grey) speakers. Parameter values for model (5.1) are given in table 1 (bottom rows); after 2009, a diglossic model with the same c-values and w₁ = 0.0035 and w₃ = 0 is assumed.