The Argument
David Shenk cites the work of Betty Hart and Todd Risley on the Head Start program to demonstrate that "children of the working poor" failed to develop the "intelligence" of the children of professionals because the intervention came too late (45). Yet by using the example of Michael Jordan and the late development of his "genius," Shenk also argues that a proper environment later in life can produce a "genius" (85). Are some skills influenced by the environment only at certain periods in one's life? Or maybe the difference is only a matter of degree. Is the development of more standard (or even "fundamental") skills limited to very early environmental influence while the stand-out quality of a "genius" can be the product of later gene-environment interactions? How does this relate to animal behavior and imprinting, which can only occur during a specific time period? Are the "basic" intellectual skills studied by Hart and Risley the human equivalent of following one's mother for greylag geese (an example of imprinting)? Relate what we have learned about animal behavior (Chapter 51) and compare the effect of the environment on human "genius" to animal examples. Remember to address applicable biological themes such as continuity and change in your response.
- Justin Doong (jbdoong@gmail.com)
If we are going to compare the notion of imprinting, or more specifically the idea of the critical period involved in imprinting, to the notion of “genius development” in humans beings during certain time periods, it helps to understand the genetic technicalities behind imprinting.
ReplyDeleteAccording to Joe Peters and Christine M. Williamson, authors of Genomic Imprinting, “Genomic imprinting is a form of epigenetic regulation in mammals whereby a small subset of genes is silenced according to parental origin.” Considering that imprinting happens to do with epigenetic gene regulation, it certainly is plausible that Shenk’s idea of environmental cues playing a role in gene expression can be tied to genomic imprinting. During these critical periods, certain genes may be silenced or expressed that makes the organism more vulnerable to a long-lasting change (like fixation on a parent). The idea of varying gene expression during a lifespan has been studied extensively throughout our course – the use of DNA probes in tandem with hybridization, such as through the microarray assay (Campbell 410), has helped scientists understand the variance of gene expression during the different stages of an organism’s life, although in humans this has shown to be most pronounced during embryonic development.
But, like you pointed out Justin, Shenk notes that there do exist late bloomers like Michael Jordan who develop their “genius” much farther down the line, which starts to blur the line and raise doubt when it comes to human imprinting in regards to skill, talent, and the such. Let’s consider this – as Peters and Williamson pointed out, imprinting occurs when a small subset of genes is silenced, not expressed. But Shenk, when pointing towards the adaptive change that humans incur when the environment demands it (for instance resulting from the onset of strenuous practice and training), “induces an abnormal state for cells in some physiological systems… These biochemical states will trigger the activation of dormant genes within the cells’ DNA (69).” Notice how Shenk refers to the activation of genes, as opposed to the silencing of genes proposed by Peters and Williamson.
Perhaps, the disparity between the imprinting put forth by Peters and Williamson and the development of genius in certain periods of time as proposed by Shenk can be traced back to a difference between a derived trait that evolved over time (imprinting) and adaptive change (continuity and change). Imprinting, along with the critical period, is typically pre-programmed into an organism’s life and is almost expected to occur. The graylag geese have the critical period possibly because under normal circumstances the infant geese are supposed to be introduced to their mother, and therefore during that infant period they silence certain genes which thereby allows for imprinting. On the other hand, the idea of developmental change during certain periods as a kind of genius development occurs because the environment demands something out of the ordinary (not necessarily expected to happen) – extraordinary circumstances that call for adaptive change, which results in the manifestation of skill as seen in child prodigies. Therefore, it seems that the two proposed topics discussed may be relating to two different themes of biology – continuity and change vs. evolution.
Mark Zhang (mzhang59@gmail.com)