David
Shenk states that the past model of nature VS nurture should be replaced with the
new “dynamic development” (33) model because nature and nurture are intertwined
and are not two separate concepts. Scientist nowadays must figure out how to essentially
induce dynamic development; biotechnology can be used to further advance human
knowledge in field of epigenetics. Describe and analyze different methods of
biotechnology that can help with inducing dynamic development. Does this mean
that seemingly unchangeable traits such as height can be altered with
perseverance and environmental influence, or does Shenk’s theory apply only to
a select group of traits (If so, generalize the aspects of the traits which can
be altered and ones that cannot)? Use a biological theme as support for your analysis.
- Akshay Ramachandran (ramachandran.akshay11@gmail.com)
Shenk's concept of "dynamic development" appears to apply to the response of the human body (in the form of altered gene expression) to environmental factors in coordination with genetic material to establish who we are and how we act (Shenk 32-33). The influence of biotechnology such as cloning and inserting genes into specific cells would no longer involve the developmental reaction of an individual to an environment, but an active attempt to alter the genetic sequence, breaking from Shenk's argument on the potential for "genius in all of us," regardless of our genetic material. Additionally, it would be an understatement to say that transforming individual cells in a human beyond the embryo stage is very difficult; the average human is made up of "200 trillion somatic cells" (Campbell 230). Biotechnology applied to the concept of continuous, dynamic development through the lifetime of an individual is simply infeasible due to the sheer number of cells in a human body.
ReplyDeleteOn the other, the idea of dynamic development appears to be applicable to many, if not almost all, traits. Physical traits such as height that have traditionally been accepted as unchangeable are actually more complex than a single gene. In fact, polygenic inheritance, "the additive effect of two or more genes on a phenotypic character," applies to many traits ranging from skin color to more complex traits, such as height, which depends on a range of genes such as those that affect muscle and bone development (Campbell 274). Shenk points out that "the more complex the trait, the farther any one gene is from direct instruction" (Shenk 26). So while the status quo is to acknowledge height as a directly-inherited trait that cannot be changed by environmental influence, the opposite is actually true. This can be explained by the increased points along the genome and gene expression which the environment can act upon. For example, environmental factors such as strenuous exercise can change the epigenetic material, "the packaging that surrounds DNA," thus changing the level of transcription of the DNA code to RNA that would then be translated into proteins that directly carry out body functions. The environment can also influence gene expression and thus the phenotype at several other points throughout the process. By causing specific responses from the regulatory mechanisms of the body that form the endocrine and nervous system, the environment can also directly affect RNA translation to proteins and the function of proteins (through inhibiting or activating substances) (Campbell 356). Environmental factors including diet and amount of activity can affect these regulatory processes for any of the genes that contribute to the height of an individual, making this trait an example of a phenotype that can definitely altered. The response of the body to different environmental factors and their effect on the phenotype of the individual are an example of the biological themes of regulation as well as continuity and change. The mechanisms affecting gene expression regulate phenotype given specific environmental stresses and conditions, leading to a fluid phenotype that changes in response to the environment. Perhaps an example of a completely unalterable trait would be blood type. The genetic inheritance of the ABO blood groups involves strictly six different genotypes and four different phenotypes that are directly inherited and generally cannot be altered whatsoever (Campbell 273). Certainly, in special cases, such as those of non-identical twins sharing a womb, the blood type can still be affected by the pre-natal environment (information from http://anthro.palomar.edu/blood/ABO_system.htm). However, Shenk's theory is less applicable in this case. Nevertheless, for more complex traits such as height, athletic ability, and intelligence (however it may be defined), a rigid, genetic blueprint seems highly unrealistic.
- Justin Doong (jbdoong@gmail.com)