Daniel Dennett argues that without language there is no consciousness, there is no self, and thus animals and baby are not conscious. Very interesting.
R. Aler, D. Borrajo, and P. Isasi. Proceedings of the 2001 Congress on Evolutionary
Computation CEC2001, page 1220--1227. COEX, World Trade Center, 159 Samseong-dong,
Gangnam-gu, Seoul, Korea, IEEE Press, (27-30 May 2001)