In footnote 90, according to Darold Treffert, Savant
skills have been shown to emerge in “elderly persons [sic]“ (276) after
fronto-temporal dementia and even in “non-disabled, “normal” persons [sic]”
(276) following head trauma. Do you think that savant skills are unexpressed
genes in the brain that may be inadvertently activated following head trauma or
dementia? Given that savant skills do appear after head trauma and dementia,
what do you think the selective advantage is of someone who develops savant
skills after a head injury or dementia versus someone who does not develop
savant skills? Finally, in reference to
Shenk’s GxE, with today’s society showing more favorable conditions for those
who do have extraordinary abilities, do you think that because more and more
people are studying harder and working harder, the environment is causing the
expression of genes in the brain that cause savant abilities? Try to relate
your response to our biology theme of continuity and change and Chapter 18 in
Campbell.
-Edward Wu (edwardwu0@gmail.com)
Savant syndrome is a condition that provides substantial evidence for David Shenk’s GxE model of the interdependent relationship between an individual’s genetic composition and the external stimuli of the individual. Upon impairment or deactivation of the fronto-temporal lobe of the brain’s left hemisphere, whether through head trauma or a particular form of dementia, the right hemisphere of the brain overcompensates for the loss in activity via an alternation in gene expression. This alteration in gene expression is the direct cause of the highly specialized skills developed by savants by altering “their way of thinking and observing, shifting attention away from meaning and understanding and toward detail” (90). Through this process, it is apparent that DNA sequences are not a blueprint for the intellectual capabilities of an individual, but a contributing factor that is largely influenced by the environment and stimuli that the individual encounters. This point was reinforced by Shenk in footnote 90, in which savant skills were both induced and observed via brain surface electrode exploration, and the conclusion was made that “previously hidden, latent interests, talents or abilities quite suddenly, and surprisingly, emerge[d]” (277). Thus, it can quite clearly be reasoned that via the deactivation of the fronto-temporal lobe, a substantial change in gene expression occurs in the right hemisphere in which either repressed or entirely new capabilities arise, likely due to altered genes resulting in altered protein production (such as crucial growth factors that stimulate cell proliferation and differentiation, as revealed Chapter 18.5 of Campbell). This process is also markedly similar to Shenk’s proposal that intelligence develops via a process, and is not simply inherited via genetics.
ReplyDeleteIn terms of selective advantages, the development of savant skills following an external stimulus that causes a deficiency in the fronto-temporal lobe enables such an individual to maintain a higher level of fitness than an individual with autism or dementia who did not develop savant skills. The higher level of fitness can be attributed to the fact that savants have a higher capability to recall intricate details and perform specialized tasks that others cannot due to the distinctions in their gene expressions. As evidenced by a study published by ScienceDaily on November 2, 2011, autistics should not be specifically noted for their shortcomings, but savants should have their unique capabilities emphasized and utilized in society (http://www.sciencedaily.com/releases/2011/11/111102161045.htm).
In response to Edward’s proposal that savant developments would be favored due to society’s emphasis on intellectual achievement and progress, I would disagree. Evolutionary time would be required for such a development to occur, which would consist of altering gene expression to favor a certain environment. Quite simply, gene expression cannot be manipulated by the environment in the course of a few decades, and the development of savant skills is such a very remote and isolated development that it would very rarely provide a selective advantage.
Nick Sotos (nsotos13@gmail.com)