I’m a fellow of wide interests, but on this blog I try to be single minded and ask So what? of every thing I report. So what does this or that bit of news have to tell us about the origins of language? Mainly, C&C’s new book argues in favor of the position I took a few years back in my own book about how language began (Babel’s Dawn). Our ancestors became community minded enough to be willing to share knowledge, and turned to using their babbling sounds in a meaningful way. Others were able to repeat and use the same sounds. Over time the speech became more elaborate, but retained its learnability for the simple reason that any expressions that were too hard to learn disappeared from use. Also the brain developed improved capacity for paying attention, combining perceptions, expanding working memory, etc. I think Christiansen and Chater would agree with that account, although I don’t think they focus so much on the rise of communal dependence for survival and they are not much interested in the biological side of the story.
One important point they contribute to the narrative is the “now or never” matter. Oral languages must be understood as they are spoken. There is no time for the kind of processing required for the hierarchical trees used by generative grammarians. Systems developed for computers also tend to use some form of hold-and-parse method in which the sentence is taken whole and subjected to various analytical procedures. Humans, however, cannot hold sentences of any length and must interpret as the sentence arrives. Presumably, today’s language users can understand more complex utterances than could be handled by the first speakers—after all, there is no reason to assert a priori that the first speakers were more capable than today’s chimpanzees and bonobos. We know from experience that modern apes can use some brief sign language, but not more than that.