An interesting article for your enjoyment
I’ve taken snippets from it for your review.
**Nature Neuroscience **- 9, 1226 - 1229 (2006)
Published online: 26 September 2006; | doi:10.1038/nn1766
What developmental disorders can tell us about the nature and origins of language
Gary Marcus & Hugh Rabagliati-- Gary Marcus and Hugh Rabagliati are at the Department of Psychology, New York University, 6 Washington Place, New York, New York 10003, USA.
[snip]
*“The case of AZ provides evidence supporting the existence of a genetically determined, specialized mechanism that is necessary for the normal development of human language.”
We very much admire both lines of work—the care taken by modularity’s critics in investigating the overlap between language and other aspects of cognition, and the detailed case studies of how specific aspects of language can be dissociated within well-defined subgroups, as undertaken by modularity’s advocates. (There is also interesting work on the opposite sorts of cases such as Williams syndrome, in which afflicted members have marked deficits in domains such as spatial cognition, but comparatively spared language8, 9.) At the same time, the mutual inconsistency of the two conclusions is striking.
One sees a similar lack of consensus in discussion of the significance of the gene FOXP2, initially noted in studies of a severe inherited speech and language disorder10, 11, 12 found in the British KE family13. Early debate (before the gene was identified) focused on the specificity of the disorder, which apparently afflicts both language and orofacial motor control13. Recent debate has focused on the relation between FOXP2 and recursion, the ability to embed and conjoin units of a language (such as phrases or words), which underlies much of modern linguistic theory. Advocates of a link between the two have argued that FOXP2 may “confer enhanced human reiterative ability [recursion] in domains as different as syntax and dancing14.” In contrast, one recent high-profile paper states that it is highly unlikely that FOXP2 has anything to do with recursion15. A third perspective16, meanwhile, uses the wide-ranging effects of FOXP2 expression13 to criticize the suggestion4 that recursion might be the only mechanism unique to both humans and to language, suggesting that the FOXP2 facts “refute the hypothesis that the only evolutionary change for language in the human lineage was one that grafted syntactic recursion onto unchanged primate (name removed by moderator)ut-output abilities.” Among these three reports, one sees FOXP2 as essential for recursion and by extension language evolution, one sees that FOXP2 as not important for what is unique about human language, and a third provides evidence that recursion is not the only unique contribution to language. As FOXP2 is expressed in many species apart from humans17, and as the gene is expressed in the lungs as well as as the brain,18 the situation is clearly complex19.*
[snip]
*We suggest a return to first principles—specifically the logic of evolution, or what Charles Darwin called “descent with modification”. As Darwin wrote, “the existing forms of life are the descendants by true generation of pre-existing form.” That is, the systems that currently exist have a two-part evolutionary history: something borrowed, something modified.
Although the “survival of the fittest” strand of Darwin’s thought has, in the form of adaptationism, often been prominent in evolutionary approaches to psychology, the importance of descent with modification has generally received less attention. A focus on adaptation alone appears to be implicit, for example, in a suggestion from evolutionary psychology that "There is no more reason to expect any two cognitive mechanisms to be alike than to expect the eye and the spleen, or the pancreas and the pituitary to be alike.“20 But this position overlooks the importance of the causal mechanism of descent with modification. Language evolved only relatively recently, probably within the last few hundred thousand years, presumably out of other neural substrates. It would thus seem unlikely that language and cognition would really be as distant as eye and spleen (which have been diverging for roughly a thousand times as long).”*
[snip]
“
The logic of descent with modification, however, suggests that fine-grained data drawn from anonymous individual profiles of particular children could be critical to elucidating rare but theoretically important developmental trajectories. A composite measure of cognitive ability, for example, might not correlate with a composite measure of language, even though deficits in more specific cognitive abilities such as inhibition might correlate with a specific deficit in language such as perseveration.”
nature.com/neuro/journal/v9/n10/full/nn1766.html
I love to read:thumbsup:
