How languages can live together without killing each other
Why Castilian didn't smother Galician
Those of you who are concerned that linguistic globalisation will eventually steamroller local tongues into extinction should take heart from a study by a team from the Universidade de Santiago de Compostela, which has mathematically proved that two languages can live together in peace and harmony.
Jorge Mira Pérez and colleagues considered the co-existence of Castilian and Galician in Spain's northwestern province of Galicia. The former, commonly referred to as "Spanish", is of course a language of international importance, while the latter is spoken by around three million people, mainly in its native territory.
Traditional analysis of "competing" languages points to the eventual extinction of one, as was pretty much the case with Scottish Gaelic and English, Welsh and English, and Quechua and Spanish, as the researchers note.
This hasn't happened with Castilian and Galician, but there's a specific set of reasons for this. According to the researchers, the continued survival of both can happen "only where there is a stable bilingual group, and this is possible only if the competing languages are sufficiently similar".
The team has applied some hefty maths to prove their point. The full-fat workings of The importance of interlinguistic similarity and stable bilingualism when two languages compete can be found  down at the New Journal of Physics, but the upshot of the matter is that since Castilian and Galician share a similar "status" among the population and both are closely related, or "similar", Romance tongues, there's every reason to believe they will continue to live side-by-side.*
Pérez explained: “If the statuses of both languages were well balanced, a similarity of around 40 per cent might be enough for the two languages to coexist.
"If they were not balanced, a higher degree of similarity (above 75 per cent, depending on the values of status) would be necessary for the weaker tongue to persist.”
It's not just about status
Of course, subjecting language interaction to a mathematical model can't tell the whole story. In their paper, the researchers note: "Firstly, the model does not consider possible alterations of the relative proportions of the linguistic groups due to immigration, emigration or differential birth and/or death rates.
"Secondly, partially related to this is the consideration that the relative status of the two languages may well vary in time."
Regarding this second point, we asked Pérez if Galician was given an artificial "boost" following the death of Franco, in that a renewed sense of Galician identity actively promoted the use of a language which had been supressed under the dictator's regime.
He said: "Yes, sure. Take into account that during Franco's regime only the use of Castilian was permitted; the other three languages of Spain (Galician, Catalan and Basque) were completely forbidden. Nowadays the situation is very different: Galician, Catalan and Basque are co-official with Castillian, there are TV channels, newspapers, etc in these languages."
While Basque has indeed enjoyed a renaissance, the researchers' mathematical model would probably have doomed it to die. Pérez concluded: "Basque is completely different, not only from Castilian, but from any other European language (English is far closer to Castilian than Basque is, for example). From my point of view, it is only the political support of Basque which has allowed its survival." ®
Those of you with a mathematical bent might enjoy this video abstract of the team's findings, presented in mighty English:
* Galician is either a language in its own right, or a dialect of Portuguese, depending on your viewpoint. Suffice it to say, it has plenty in common with both Portuguese and Castilian.