Most human beings learn at least one language with amazing ease.
Noam Chomsky proposed that human beings were biologically prepared to learn language. His evidence included a number of observations of how language is typically acquired. B. F. Skinner felt that language was learned through operant conditioning. If a sound were to be followed by something reinforcing to the baby, the baby would be more likely to repeat that sound again. Shaping would lead from approximations of the correct sound to speech that fits the speech patterns of the parents or others in the child's environment.