Twitter Evolution: Converging Mechanisms in birdsong and human speech

In my last post, I made reference to the similarities between birdsong and human speech, and how the development of these two might inform us on the evolution of language. So, it comes as a pleasant surprise that there is a new review in Nature Neuroscience on the very topic: Twitter Evolution: converging mechanisms in birdsong and human speech (click here for paper). I haven't yet had chance to fully read the paper, but I think the following figure is quite instructive of the connective complexity we're dealing with: