"How and why do languages change over time? Could the way an individual child develops affect aggregate language change? What do the mechanisms of change tell us about the evolution of language in our species?" "The "cue-based" approach to language acquisition presented here is a radical departure from formal models of language learning. Lightfoot challenges conventional understanding by showing that language change is essentially contingent - unpredictable but explainable; and he contests how far natural selection enables us to understand the evolution of the language faculty in the species."--BOOK JACKET.