The Argument
In the final chapter of The Argument, David Shenk describes the influence of epigenomes and how "changes to the epigenome can be inherited," allowing individuals to pass on traits developed through a specific lifestyle (159). How does the knowledge that we can control our inheritance affect our decisions throughout life? Will this understanding simply become another burden or a source of motivation to work hard? Also, do you believe that it is possible to complete a "Human Epigenome Project" to map the epigenome in the same way the DNA genome was mapped by the Human Genome Project? Will an improved understanding of our epigenome allow us to better recognize or even combat genetic/epigenetic disorders in the same way as the Human Genome Project? Or, will the epigenome simply become another source of "excuses" for the lack of success? Use your knowledge of the epigenome and gene regulation from Chapters 16 and 18 in the Campbell textbook to help you answer these questions. Remember to consider the biological themes of Evolution and Continuity and Change in your response.
- Justin Doong (jbdoong@gmail.com)
The knowledge that we have more control over our traits and the traits we pass on to our children should lead us to make healthier decisions through life. Decisions made with the mindset of "you only live once" should perhaps be rethought; while consequences may not be apparent to the decision maker, they may have effects on his or her epigenome, therefore effecting their children. Genetics are unchangeable and therefore were blamed for personal failure. Unlike genetics, we can change our epigenetics through our actions. We cannot blame something within our control for possible failure, as we'd only be blaming ourselves. Rather, the understanding of epigenetics will motivate people to work to improve their epigenetics through living a healthier lifestyle.
ReplyDeleteA human epigenome project, with the purpose to "identify, catalogue and interpret genome-wide DNA methylation patterns of all human genes in all major tissues", in fact is currently underway! (http://www.epigenome.org). The Human Epigenome Project (HEP) is analyzing the methylation patterns in order to determine certain patterns that correspond with, among other things, "tissue type and disease state." Methylation generally inactivates genes (Campbell 358), so the HEP is analyzing the effects when certain genes are inactivated in cells. The scientists working on the HEP hope that a better understanding of the epigenome will lead to a better understanding of diseases and how to diagnose them (http://www.epigenome.org).
Epigenetics adds a whole new concept regarding the biology theme of Continuity and Change. The idea of Continuity is expanded because not only does the offspring of an organism inherit its genetic material, but it also inherits its epigenetics. Similarly, the concept of Change now includes the idea that epigenetics changes with our actions.
As optimistic as David Shenk and Brandon are about the power of this discovery, I don’t believe that the knowledge of Genes x Environment will have a major effect on our everyday life. For one thing, the knowledge that we can achieve greatness through hard work and persistence, and not be limited by our genes, is not sufficient motivation to pursue greatness. Shenk himself admits that, “You have to want it, want it so bad you will never give up, so bad that you are ready to sacrifice time, money, sleep, friendships, even your reputation” (120). For instance, one of the basic ethology questions outlined in the textbook asks, “How does the behavior aid survival and reproduction?” but the kind of greatness Shenk expounds about is not necessarily a selective advantage (Campbell 1121). For athletes, at least, the physical demands placed upon the body are almost dangerous; not only do athletes require a much greater intake of energy to fuel their exercise, but intense training temporarily weakens multiple body systems in order to rebuild and get stronger. Every intense workout creates microscopic muscle tears that sap energy in the following days as the tissues repair themselves. While the overall effect of this rebuilding is that muscles grow stronger, the diversion of ATP to muscles instead of other body systems could have been dangerous for early humans. Therefore, genes that inclined a human towards ‘laziness’ might have allowed the human to conserve energy for periods of famine or fending off predators, making it more likely that the human survives, reproduces, and passes on those genes.
ReplyDeleteThe immune system, too, is compromised for days after hard workouts. As with the former example, the energy spent repairing muscle fibers is diverted from the immune system, which can compromise a human’s ability to fight off infection. But exercise has more effects than tearing muscles; it depletes glycogen stores in muscles, triggers the release of stress hormones, and more. An article from the journal Sports Medicine states, “Exercise stress leads to a proportional increase in stress hormone levels and concomitant changes in several aspects of immunity, including the following: high cortisol; neutrophilia; lymphopenia; decreases in granulocyte oxidative burst, nasal mucociliary clearance, natural killer cell activity, lymphocyte proliferation, the delayed-type sensitivity response, the production of cytokines in response to mitogens, and nasal and salivary immunoglobulin A levels; blunted major histocompatibility complex II expression in macrophages; and increases in blood granulocyte and monocyte phagocytosis, and pro- and anti-inflammatory cytokines” (http://www.ncbi.nlm.nih.gov/pubmed/11929359). Again, the humans with genes that discourage intense exercise would be more likely to have fully functioning immune systems at exposure to disease, so would also be more likely to survive and reproduce.
In fact, the need to reduce energy expenditure while securing as much food as possible is so prevalent in the behavioral ecology, it has its own name: the optimal foraging model (1133). The point is, it would be very difficult to become an athletic ‘genius,’ because all humans- all animals, in facts- are naturally inclined to conserve energy. Even for other types of ‘genius,’ the dedication required to achieve greatness is not likely to win over potential mates: the one thousand hours that Shenk claims is required for true mastery of a skill equates to almost twenty-five years! The isolation of devoting oneself to an art would mean sacrificing a lot of social behaviors that humans are naturally inclined to do because it allowed us to survive in packs. Because of animals’ tendency to conserve energy, I don’t think this information will have a huge impact on human understanding of life; some people are motivated enough to pursue greatness, but everybody else is simply following the most biologically favored course.
PART ONE
Mackenzie Levy (GinnyFan@comcast.net)
I believe it is possible to complete a human epigenome project, both out of faith in the power of science and the fact that we’ve already started. In support of Brandon’s finding, other institutes around the world have begun mapping the epigenome, especially in regards to DNA methylation. According to a 2010 article from Science Daily, researchers at The Genome Institute of Singapore and The Scripps Research Institute, “mapped a major component of the epigenome, DNA methylation, for the entire sequence of human DNA” (http://www.sciencedaily.com/releases/2010/02/100203141326.htm). As with the Human Genome Project (HGP), it is impossible to say what the mapping of the human epigenome will help us to accomplish in the future. One of the researchers from the Genome Institute of Singapore explained, “Using this knowledge, scientists can now survey different cell types and developmental pathways, identify the genes affected, and characterize the functions of these genes in the process of differentiation” (http://www.sciencedaily.com/releases/2010/02/100203141326.htm). However, all of the data gleaned from epigenome sequencing is useless if the information is not applied. The epigenome project, like the HGP, would require massive amounts of data storage and analysis before patterns can be recognized and medical breakthroughs made. Still, the HGP has already managed to expand the human understanding of our genome, from “defin[ing] gene circuits and protein interaction networks” to “understand[ing] how changes in biological systems lead to cancer” (Campbell 431). If anything, analysis of the epigenome could be easier than that of the genome, because we have already mapped out the latter. Epigenome research, then, can focus on the DNA surrounding specific histones,
ReplyDeleteEventually, innovations in biotechnology and bioinformatics will lead to even greater accomplishments in genomics, and, with this new understanding of Genes x Evironment, epigenomics as well. I believe the mapping of the human genome and epigenome can lead to total understanding of gene expression and hopefully to methods of manipulating gene expression to prevent disease.
In terms of the inheritance of epigenomes by offspring, if the epigenome project presented concrete evidence of parents’ actions changing the gene expression of their children, science may be able to influence the activities of a fraction of the human population. However, humans have millions of years of evolution in favor of our behavior, and it would require a significant shock for epigenetic discoveries to influence the majority of the population.
PART TWO
Mackenzie Levy (GinnyFan@comcast.net)
Epigenetic inheritance is a relatively recent discovery. Discovered in 1999 by Enrico Coen and subsequently Daniel Morgan and Emma Whitelaw, they found that “changes to the epigenome can be inherited” (Shenk 159). These studies found that “lifestyle can alter heredity” (Shenk 161). This is a very interesting revelation. This means directly “what an individual does in his/her life before having children can change the biological inheritance of those children” (Shenk 161). With all of these conclusions proven correct, a change in the face of heredity has been made. While all research on this specific issue has not yet been established, a firm foundation supports that disease and physical characteristics are plausible to be passed down among generations. For example, a large football player is more likely to have children that are larger and bulkier. More importantly, there is common belief that “epigenetic modification may be at the root of many disease” (http://proquest.umi.com/pqdweb?index=2&did=2485162641&SrchMode=2&sid=8&Fmt=3&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1334289436&clientId=15232). This discovery may very well be life changing. The possibility that heretic disease is caused by the epigenome could lead to the creation of a whole new field of genetics and diet. The discovery of this heredity could lead to a new field of dieting for pregnant women. Knowledge of epigenetic heredity could mean that what a woman eats while pregnant could affect her own offspring.
ReplyDeleteAnother interesting event that could arise from this discovery is “geneticism”, discrimination based on genetic superiority. A new form of “sexual selection” may develop wherein humans are breeding better genetic specimen to create more advanced intellectuals, athletes, and thinkers. This process would be very similar to selective dog breeding to create thoroughbreds that would best perform in a dog show. Sexual selection does exist on a small scale in the natural world where “individuals with certain inherited characteristics are more likely that other individuals to obtain mates” (Campbell 481). Geneticism could develop into people being discriminated against depending on whether or not they were born by ideal parents.
In regards to the Human Epigenome Project, it “was established in 1999, when researchers in Europe teamed up to identify, catalogue and interpret genome wide DNA methylation patterns in human genes” (http://proquest.umi.com/pqdweb?index=0&did=1545217061&SrchMode=2&sid=6&Fmt=3&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1334289243&clientId=15232). Methylation is important in whether or not genes are expressed because “DNA methylation… can repress transcription” (Campbell 358). Thus, some genes that need to be expressed are not, which can lead to many diseases namely cancer.