So, I've read the Hauser/Chomsky/Fitch paper, and a few things struck me. For one, they claim that the language faculty, okay, syntax, is a (near) optimal mechanism for connecting the sensory motor system to the conceptual one. If true, why should displacement be a part of it?Why should recursion be a part of it? Ideas may be expressed in discrete units; the Piraha, in fact, may lack recursion altogether. Of course, at the end of the article, the authors claim that recursion may have evolved independently in a domain-general fashion, becoming specialized only later. I'm willing to accept this conclusion, but it says nothing on how our little group characterizes language. All of that is to say, then, supposed feature-checking mechanisms are optimal? For all our spouting of 'elegant rules', I would think a system without movement and D-features would be a better exemplar of the cleanliness of mental operations. I believe there are theories out there that do without movement, so maybe being an evolutionary linguist means taking a hard, difficult look at the level of theoretical complexity that we've devised.
Furthermore, if it turns out that recursion isn't a part of the language faculty (per the suggestion that it's used for other mental concerns, does this mean that birds also have language, albeit with a much reduced vocabulary? I believe the article said said that was a limiting factor to the classification of their abilities. Along this line, there is a professor at Duke who is studying songbird neurolgy in order to decode how language is learned, eventually applying it to human nuerobiology:
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA
Address for correspondence: Eric D. Jarvis, Department of Neurology, Duke University Medical Center, Box 3209, Durham, NC 27710, USA. Voice: 919-681-1680; fax: 919-681-08772. firstname.lastname@example.org
Vocal learning, the substrate for human language, is a rare trait found to date in only three distantly related groups of mammals (humans, bats, and cetaceans) and three distantly related groups of birds (parrots, hummingbirds, and songbirds). Brain pathways for vocal learning have been studied in the three bird groups and in humans. Here I present a hypothesis on the relationships and evolution of brain pathways for vocal learning among birds and humans. The three vocal learning bird groups each appear to have seven similar but not identical cerebral vocal nuclei distributed into two vocal pathways, one posterior and one anterior. Humans also appear to have a posterior vocal pathway, which includes projections from the face motor cortex to brainstem vocal lower motor neurons, and an anterior vocal pathway, which includes a strip of premotor cortex, the anterior basal ganglia, and the anterior thalamus. These vocal pathways are not found in vocal non-learning birds or mammals, but are similar to brain pathways used for other types of learning. Thus, I argue that if vocal learning evolved independently among birds and humans, then it did so under strong genetic constraints of a pre-existing basic neural network of the vertebrate brain.