The Babbling Stage of Infancy

It is interesting and perhaps surprising to realize that most mammals lack a capacity for complex vocal learning of this sort. Current research suggests that aside from humans, only marine mammals (whales, dolphins, seals), bats, and elephants have it. Among primates, humans appear to be the only species that can hear new sounds in the environment and then reproduce them. Our ability to do this seems to depend on a babbling stage during infancy, a period of vocal playfulness as instinctual as the young bird’s subsong. During this stage, we appear to fine-tune our vocal control so that, as children, we can hear and reproduce the words and phrases of our adult caregivers.

W. Tecumseh Fitch describes the link between infant vocalizations and the ability of humans to vocalize extensively. This links to Chomsky's speech-center of the human brain.