Meeting Abstract
Vocal learning has evolved repeatedly and independently in several lineages of birds and mammals. This pattern of evolution begs interesting questions about both the selective advantages of this complex cognitive trait and the neurogenetic mechanisms that give rise to it. Vocal learning is commonly treated as a binary trait that species either possess or lack entirely. This binary view has been a useful starting place for examining the origins of vocal learning, and has furthered our understanding of the neuroarchitecture and gene expression specializations that are shared across vocal learning taxa like humans, songbirds and parrots. This binary framework is also misleading though, as specific components of the learning program – such as the timing, extent and nature of what is learned – vary widely among species. This variation led Brenowitz and Beecher (2005a,b) to argue that vocal learning should be viewed as a multi-dimensional trait in which different dimensions may be under different selective forces and governed by different mechanisms. They argued that such a framework would be particularly powerful when combined with a comparative perspective. Here we revive and expand this framework by describing six discrete dimensions of vocal learning and discussing evidence of variation in each within and across species. We then highlight several recent examples of work that focus on one of these dimensions and examine either evolutionary hypotheses explaining this variation or neurogenetic mechanisms that underpin it. We end by discussing how new tools and analytical approaches to test these hypotheses and highlight key areas in which a multi-dimensional framework, coupled with a comparative perspective, will rapidly advance our understanding of why and how vocal learning has evolved.
