In the footnote 162, Shenks cites a study that used mice with memory-impairing genetic defects. The mice were then exposed to a "stimulating environment"(348). This stimulating environment not only increased the memory of the mice, but also the memory of their offspring. In essence, environmental factors and choices affect the genetic makeup of future generations.
Will this change in genetic makeup necessarily be advantageous to future generations? Why might they not be advantageous? If a family is made up of all skilled athletes, why might a future offspring not excel as an athlete? In your response, comment on the relationship between epigenetics and evolution.
Jonah May (Jonah2020@aol.com)
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ReplyDeleteThe discovery that Lamarck may have been on to something likely will be the guiding force behind many of the great genetic discoveries in the near future. Through the process of genomic imprinting in mammals, “methylation permanently regulates expression of either the maternal or parental allele of a particular genes at the start of development” (Campbell 358). Following this idea, it is first evident that indeed histone modification and acetylation can and likely is passed down from generation to generation. The other side of this, however, is that the modification is only guaranteed to exist at birth, and therefore, all a parent can do is set their offspring up for the best potential outcome, while the rest if left up to the GXE influence.
The implications of the new epigenetic understandings are an increased importance on one’s life behaviors. Though currently women are scrutinized while pregnant with their children, potential fathers might be just as important for ensuring that their child does not come out of the womb with harmful histone modification as a result of a negative lifestyle. Shenk notes this ideal to state that “lifestyle can alter heredity”. He goes on to state that “information is transferred from one generation to the next by many interacting inheritance systems” (Shenk 161). This implies that the oversimplification of inheritance into simple punnett squares and Mendelian inheritance may not fully explain the importance of lifestyle of genetics.
With a changing view of genetics, surely a changing view of evolution must be adapted. Though it is slightly grandiose to exclaim “welcome back, monsieur Lamarck” (Shenk 160), the future holds great promise for new evolutionary understanding. To begin with, we may one day learn not how to change genes and DNA as we have been searching to do, but rather to disregard certain DNA and genes through histone modification and avoid the issue of DNA transcription and recombination all together.
The ultimate issue with improving “the memory of… eventual offspring” (348) is in what is lost in the process. Though histone modification may allow mice to gain more intelligence, this does not mean that certain other survival factors are ultimately limited as a result. It is clear that through homeostasis, a limited number of body activities can be carried out without taxing the body too heavily. Each improvement likely comes at the expense of another adaptation, much like how humans’ strong brains come at the cost of strength and power out in the wild. Though we can never know what will come for the next generation, it is important to live as you’d hope your future children will, both to create a proper environment, and to pass on the best genetic material. Who knows, your actions might just end up preserved on Facebook for all of your grandchildren to gawk at.
Jacob Yomtoob (jakeyomtoob@gmail.com)
It has been long known that there are many things passed down through genetics. A child will often mirror a parents propensity towards alcoholism, cancer or obesity. Yet, as Shenk has stated all along, these genetics do not certainly determine a child’s future. If a case study similar to the one done with mice was to be done on humans, maybe the same results would show up: that children inherit skills their parents developed before their conception. Yet, in humans these results may be seen due to similar environments. A culture of running that produced a parent athlete will surely produce a child as well. Often, a cultural influence can be as strong or stronger than a parental one. As in the case that Shenk describes on page 103with the village of Kenyan runners, the culture of running is deeply seated within every one of its citizens. Therefore, a culture than pressures a mother to acquire an ability may pressure a child to do the same.
ReplyDeleteYet, there is another factor to human epigenetics. Human culture is always changing; the values and demands are always in flux. Therefore, it would be rare that a culture would have the same influence on a child twenty or thirty years later than a parent. It then falls to a “nurture” environment. The parents being skilled at something would probably inspire a child to follow in their parents foot steps. The kind of inheritance described in mouse experiment is interesting, yet probably not applicable to humans. It has been seen over and over again that the offspring of geniuses rarely live up to their parents, and therefore probably do not inherit such epigenetic qualities.
Shenk quotes Moshe Szyf on page 163 in saying that “people used to think that once your epigenetic code was laid down in early development, that was it for life, but life is changing all the time, and the epigenetic code that controls your DNA is turning out to be the mechanism through which we change along with it”. This information certainly pertains to the biological theme of evolution. This epigenetic mechanism is constantly changing and adjusting to our environment and is therefore evolving better and more useful traits for us to use. The Campbell textbook points out on page 358 that “epigenetic variations might help explain why one identical twin acquires a genetically based disease, such as schizophrenia, but the other does not, despite their identical genome”. Such epigenetic qualities are evolutionary advantages and may someday help eradicate inherited disorders completely. And I agree with Jacob Yomtoob when he states that “the (epigenetic) modification is only guaranteed to exist at birth, and therefore, all a parent can do is set their offspring up for the best potential outcome, while the rest if left up to the GXE influence”. For now, it is yet unknown how the epigenetic mechanism truly functions, yet all we can do is hope that our good genes get passed down,. And, if the bad genes get inherited, we hope that our grandchildren will interact with another factor that will help them overcome it.
(Liz Gorelick lizgorelick@yahoo.com)