Bird song systems: Evolution

This article presents the vocal and auditory pathways of vocal-learning birds and a hypothesis about their evolution. These pathways control the ability to produce learned song in the few groups of birds that have vocal learning abilities, songbirds, parrots, and hummingbirds. These species have served as model systems to study neural mechanisms of spoken language, for which vocal learning is a critical behavioral substrate. Their vocal pathways are proposed to have evolved out of a preexisting motor pathway. © 2009 Elsevier Ltd All rights reserved