[6 Apr 2004]
Below are e-mail responses from researchers of bird brain to my message concerning their papers Haesler et al and Teramitsu et al. See also commentaries by the academic institutes of the researchers, based on talking with them, in university news release, press release by Max Planck Society and this university release. See the related texts for discussion of the issue.
All the responses seem to try to give "speech" a new meaning of "motor actions", rather than "coordination of motor actions to produce linguistic utterances". Obviously, if speech is "motor actions", then all animals have speech skills. So when people (including these researchers) say that only humans among mammals have speech, they don't mean "motor actions", they mean "production of linguistic utterances". This is certainly a cortical function, and hence has no homology in birds. Faced with this question, this researchers try to confuse the issue by extending the definition of speech. In the case of Jarvis, it may be that he genuinely believes that some non-cortical structures in the human brain have speech functionality, notwithstanding the contrary neuropsychological evidence.
It should be noted that the issue of cortex in humans vs. non-cortex in birds is not mentioned in all the commentaries above, even though these are for non-experts that would not be expected to know it.
Dear Stephanie A. White, In your recent paper "Parallel FoxP1 and FoxP2 Expression in Songbird and Human Brain Predicts Functional Interaction" you are referring to the relation between bird song and human speech. However, according to current theories, human speech is controlled by some part of the cerebral cortex, which is undeveloped in birds, and bird song is controlled by some nuclei that do not have parallels in the mammalian brain. In other words, the control of human speech and bird song is done by two evolutionary unrelated systems. Are you suggesting that the current theories wrong? Or that the unrelated systems converged on using the same gene? Thanks, Yehouda Harpaz++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
From: "Dan Geschwind"==============================================================
To: "Yehouda Harpaz" ; Sent: Sunday, April 04, 2004 4:26 PM Subject: Re: FoxP, birds song and human speech. Dear Yehouda: Human speech involved parallel distributed systems that are not fully understood, t clearly involve subcortical structures in which fox genes are expressed. Speech and all complex motor movements have significant basal ganglia involvement, thalamic etc.... best, DG Dr. Daniel H. Geschwind Associate Professor Director, Neurogenetics Program Department of Neurology 710 Westood Plaza, RNRC 1-145 UCLA School of Medicine Los Angeles, CA 90095
----- Original Message ----- From: "Stephanie White"==============================================================
To: "Yehouda Harpaz" Sent: Friday, April 02, 2004 6:28 PM Subject: Re: FoxP, birds song and human speech. An upcoming paper in the Journal of Comparative Neurology clarifies avian brain structures relative to mammalian brain. It is now clear that the avian brain contains much more pallium than previously thought when it was named 100 years ago. Pallium gave rise to cortex. The first author is Reiner. I'm not sure when it will make it to print. Meanwhile, I agree that LANGUAGE is clearly cortical, but the actual control of the muscles used for speaking will have a basal-ganglia component. Interestingly, even strokes of the human cerebellum sometimes end up disrupting speech.
From: "Erich D. Jarvis"
To: "Yehouda Harpaz" ; ; Sent: Friday, April 02, 2004 3:11 PM Subject: Re: FoxP, birds song and human speech. Dear Yehouda, We are saying exactly what you state below. That the current evolutionary theories of how avian and mammalian brains are related are wrong. That there are similarities between a so far not well characterized human language system with the well characterized song bird vocal learning system. Some of the similarities for the language/song specific behaviors are thought to be the result of convergence. Others similarities outside the language/song systems are the results of common ancestry with stem amniotes. Details on the answers to the two questions you have below are coming out in two papers that will be published within the next 1-3 months: > Revised Nomenclature for Avian Telencephalon and Some Related Brainstem Nuclei. A Reiner, L Bruce, A Butler, A Csillag W Kuenzel, L Medina, G Paxinos, D Perkel, T Shimizu, G Striedter, M Wild, G Ball, S Durand, O Gunturkun, D Lee, CV Mello, A Powers, S White, G Hough, L Kubikova, TV Smulders, K Wada, J Dugas-Ford, S Husband, K Yamamoto, J Yu, C Siang, ED Jarvis (2004) J. Comp. Neurol. (in press, May 2004). Learned Birdsong and the Neurobiology of Human Language. ED Jarvis, In: Behavioral Biology of Bird Song, HP Zeigler, P Marler (eds.) (2004) Annals of the New York Academy of Sciences (in press, June 2004). Sincerely, Erich Jarvis Erich D. Jarvis, Ph.D. Assistant Professor Department of Neurobiology, Box 3209 Duke University Medical Center Durham, North Carolina 27710 (919) 681-1680 Phone (919) 681-0877 Fax http://www.jarvislab.net/