The political economy of linguistic cleavages
This paper uses a linguistic tree, describing the genealogical relationship between all 6,912 world languages, to compute measures of diversity at different levels of linguistic aggregation. By doing so, we let the data inform us on which linguistic cleavages are most relevant for a range of political economy outcomes, rather than making ad hoc choices. We find that deep cleavages, originating thousands of years ago, lead to better predictors of civil conflict and redistribution. The opposite pattern emerges when it comes to the impact of linguistic diversity on growth and public goods provision, where finer distinctions between languages matter.
That is from an accepted manuscript at the Journal of Development Economics.
From the conclusion, some benefits and drawbacks on focusing on linguistic diversity (rather than ethnic):
Finally, we have focused on linguistic diversity, as a measure of a broader concept of ethno- linguistic heterogeneity, and even more broadly as a proxy for cultural diversity. One advantage of focusing on languages is that linguistic distinctions are quite objective: it is easier to judge whether two populations speak different languages than to decide whether two populations belong to different ethnicities, a more amorphous concept (precisely for this reason, ethnic categorizations are often based on linguistic divisions, particularly for Africa). Another advantage is that data on linguistic divisions, particularly in the form of trees, is more readily available than data on the genealogical structure of ethnic groups within countries. There are, however, drawbacks to focusing on languages: to the extent that linguistic divisions are imperfect measures of the source of diversity that matters most, this should lead to downward bias on the estimates of the effect of diversity on political economy outcomes. In principle, the methodology we have developed for linguistic trees should be applicable to other kinds of differences between populations. With advances in population genetics, population phylogenies have become more widely available. Although this data is not yet available in a single format such as the Ethnologue for languages, applying our method to genetic data could lead to fruitful advances in the study of the political economy of cultural diversity.
I’d caution against jumping on the genetic data bandwagon, though.