Jeff in PNAS

Now in the Proceedings of the National Academy of Science, "Endogenous sources of variation in language acquisition" by Jeff, Chung-hye Han, and Julien Musolino. The paper argues that, "when the exposure language is compatible with multiple grammars, learners choose a single, systematic, grammar at random," based on its finding that some idiolects of Korean have the verb in a higher position than others, without there being differences in the linguistic input that would explain this.