September 20, 2012
Language is one of the best examples of a cultural evolutionary system. How vocabularies evolve has been extensively studied, but researchers know relatively little about the stability of structural properties of language - phonology, morphology and syntax. In their PLoS ONE paper, Dan Dediu (MPI's Language and Genetics Department) and Stephen Levinson (director of MPI's Language and Cognition Department) asked how stable over time the structural features of languages are – aspects like word order, the inventory of sounds, or plural marking of nouns.
"If at least some of them are relatively stable over long time periods, they promise a way to get at ancient language relationships," the researchers state in their paper. "But opinion has been divided, some researchers holding that universally there is a hierarchy of stability for such features, others claiming that individual language families show their own idiosyncrasies in what features are stable and which not.
Using a large database and many alternative methods Dediu and Levinson show that both positions are right: there are universal tendencies for some features to be more stable than others, but individual language families have their own distinctive profile. These distinctive profiles can then be used to probe ancient relations between what are today independent language families.
"Using this technique we find for instance probable connections between the languages of the Americas and those of NE Eurasia, presumably dating back to the peopling of the Americas 12,000 years or more ago," Levinson explains. "We also find likely connections between most of the Eurasian language families, presumably pre-dating the split off of Indo-European around 9000 years ago."