Language as shaped by the brain

In a recent Language Log comment, Shimon Edelman pointed to "great new paper by Christiansen and Chater" on the "the logical problem of language evolution". During a recent trip to Philadelphia and New York that had nothing to do with language evolution, I printed the paper, and then proceeded to stay up late into the night to finish reading it. It was not just jet lag. The paper is indeed very interesting. Since it is a review that cites many primary sources that I have not read, my support is cautious, but its evolutionary argumentation against the hypothesis of innate, genetically-enconded language-specific brain machinery appears very solid. I am also sympathetic to their hypothesis that "language has evolved to fit prior cognitive and communicative constraints, then it is plausible that historical processes of language change provide a model of language evolution; indeed, historical language change may be language evolution in microcosm." But the section in which they develop this hypothesis is less tightly argued than the rest of the paper, with some just-so story-telling drifting by. Their enthusiasm may have pushed them a bit further than the very fragmentary evidence warrants, but it's not surprising that they are enthusiastic after their convincing demolition of rationalist fantasies that have been holding us back for a long time.