JIM CURRAN wrote:
Thanks Maizie, after a lifetime of teaching I’m naturally cautious about easy solutions but from my own experience inside and outside the classroom I have come to believe that there is a neurological basis for some of the learning disabilities that I encounter daily.
There seems to be quite a lot of evidence, from twin studies and other fairly robust research, to support that view. However, neither of these contributions illuminate the question to a useful extent, in part because they start off with dubious assumptions. Both the Healthcanal report and Dorothy Bishop seem to take as given that dyslexia is a distinctive condition, though neither clarify their understanding of the term; I strongly suspect that it is merely an arbitrary range within the spectrum of literary competence. Moreover, the Yale study is very limited in its scope, since it is comparing measured performance with the presence or absence of variants of rather few genes and gene regulators. The weakness of this approach is that there must be many other genes or regulators that influence the development of language capabilities, some of them in a highly non-linear manner.
Genetic control of development is a huge problem and understanding it will require large research programmes. Over the next decade or so we can expect computation to continue to get cheaper, with two effects: total genome sequencing will become cheap enough to be undertaken on each of the subjects of a study; and regression analysis on larger numbers of variables will also become affordable. When the human genome project started, it was expected to take 10 years, of which the first five were to be used to develop the methods that would be used subsequently. Fortunately, computation and genome sequencing are both being improved for many other purposes, so language development can piggyback on them.