Argument
129-130
Shenk
discusses a study led by John C. Crabbe in which mice from three different
locations were tested for their reaction to alcohol, cocaine and their activity.
The environments in the three laboratories were painstakingly held
constant, but surprisingly there were significantly different results that
could not be traced back to a single cause although they were genetically
identical mice that were in identical lab environments (129-130). Hypothesize possible
reasons for these results. Explain how this supports the GxE model for genetics
and proves the idea of genetics as a blueprint wrong. Also, how does this
relate to epigenetics and gene expression?
Alex
Casino (AlexJCasino@gmail.com)
Although researchers kept as many known variables constant during this experiment, the “hidden environment” was not taken into account. The emphasis made by this experiment was the “gene-environment interplay” (Shenk 130). After ensuring the known environmental variables were constant among the three locations, it was clear “that these hidden environmental differences had significantly affected the results” (Shenk 130). One would imagine that since the mice were genetically identical, and their environments were close to identical, then the mice would develop very similar, if not the same traits. One of the most important points taken from this experiment “was how much complexity emerged from such a simple model” (Shenk 130).
ReplyDeleteThe results of these genetically identical mice developing very different traits supports the GxE model because this proves that the environment had a great impact during development. Although the environments were painstakingly made constant, the multitude of hidden environmental factors still managed to alter the traits developed in the different mice. This proves the genes as a blueprint is wrong because according to this theory, then any organism with identical genes as another would supposedly develop the exact same traits and literally be “clones” of one another. Since these mice did have identical genes, but developed different traits, then it can be correctly concluded that the environment played a significant role and that genes themselves are not the sole blueprints to one’s development.
Epigentics is the relationship between the brain, genes, and one’s behavior (Shenk 131). It also relies on the evidence of connections between nature and nurtue. Basically, it is “the study of changes in gene activity that do not involve the alterations to the genetic code but still get passed down to at least one successive generation” (http://www.time.com/time/magazine/article/0,9171,1952313,00.html). As generations pass, there are “marks” made on one’s epigenome, which sits on top of the genome. Environmental factors are what makes an imprint on these genes because they turn on and off certain genes. Some examples would be “diet, stress, and prenatal nutrition…that is passed from one generation to the next” (http://www.time.com/time/magazine/article/0,9171,1952313,00.html). This is why some traits that a person expresses have been seen in one’s ancestors. This also shows how a smoker’s child may have a larger propensity to develop lung cancer, even though the child has not been exposed to cigarettes. As time goes one, those who take care of themselves better by living a healthy lifestyle will reproduce offspring who have a greater chance of also living healthily in order to survive and reproduce. Through evolution and epigenetics, humans that have the selective advantage of having appropriate traits turned on due to imprinting will have a greater possibility of surviving and reproducing.
(Kalista Noegroho, Kalista.dara@gmail.com)