Pierre-Yves Oudeyer is a researcher at Sony Computer Science Laboratory, Paris. He studies the origins and evolution of language, and is a specialist of computer modelling, including robotic systems, artificial intelligence, and developmental systems. His work on the origins of speech was awarded the French Prix Le Monde de la recherche universitaire, 2004. James R. Hurford is Professor of Linguistics at the University of Edinburgh. His books include Semantics (with B. Heasley, 1983), Grammar (1994), and as co-editor Approaches to the Evolution of Language (1998), all published by CUP....