Let's return to why this should be. I described Chomsky's conjecture that this fact could also help explain how we could acquire language. One of the most exciting developments of the last 10 years has been an astounding series of advances in our knowledge about actual language acquisition by children. For example, a large body of research on newborn infants has established that specific details of language structure are in place in the brains of infants even, in some cases, at birth. In many cases, linguistic knowledge is present despite the absence of any language experience that could account for the knowledge.
Children know things that they have never been taught and have never heard.
For example, infants display knowledge of specific linguistic contrasts among sounds that are not part of their mother's native language. One of the more spectacular pieces of evidence comes from a recent paper by Susan Goldin-Meadow and Jana Iverson of the University of Chicago. Spoken language is not just verbal, but is regularly accompanied by gesture. Linguistic gesture seems to be a lot like intonation, the rise and fall of pitch that is also a part of everyday speech. It doesn't convey the main message when you talk, but it does play a role in communication.