Vocal learning in birds and humans.

Vocal learning is the modification of vocal output by reference to auditory information. It allows for the imitation and improvisation of sounds that otherwise would not occur. The emergence of this skill may have been a primary step in the evolution of human language, but vocal learning is not unique to humans. It also occurs in songbirds, where its biology can be studied with greater ease. What follows is a review of some of the salient anatomical, developmental, and behavioral features of vocal learning, alongside parallels and differences between vocal learning in songbirds and humans.