The Evidence- Footnote 106
On page 304, Shenk discusses the research of the National Human Genome Research Institute and comes across the conclusion that "actual genetic differences between ethnic and geographic groups are very, very limited" (304). If that is so, why do Kenyans tend to lead in track and field events? Does it still boil down to the trainers that they have? If, as Kate Berg writes on page 304 that "all human beings are descended from the same African ancestors", and the genetic differences are not very large, why do the Africans typically have an upper hand over Caucasians in track and field events? As Bob Young writes on page 307 that if genetically every human is very similar, is it just dedication and determination that makes that Olympic participant? However, the person Young writes about, Jon Entine, claims that there are "differences that could give a fraction-of-a-second advantage to people of African ancestry" (307); is that possible?
Shivani Thakker (shivanithakker1357@gmail.com)
The Evidence: The global dominance of Kenyans in terms of their running superiority is a clear example of Shenk’s GxE model in effect. Despite the common misconception that people of Kenyan descent possess genes that are transcribed, spliced, and then translated into proteins (Campbell 336) that provide athletic advantages, it has been proven through the Human Genome Project that the genetic differences between all members of the human race are extremely minimal, as evidenced by all humans deriving from a common African ancestor via evolution. In addition, the National Human Genome Research Institute has proven that humans possess less genetic variation as a species than any other mammal (306). However, in a study published by Discover Magazine regarding phenotypic differences between races, both alternative RNA splicing and different degrees of certain gene expression (analyzed via microarray analysis) were cited as a possible explanations for the disparities in phenotypes between individuals of Asian and European descent (http://discovermagazine.com/2007/may/is-there-a-genetic-basis-to-race-after-all/?searchterm=genetics%20race). Thus, while the entire genome of the human race is apparently constant, the ability for specific sequences of nucleotides to code for multiple proteins and the different levels of gene expression between races can possibly contribute to minute physiological differences, such as in the ability to run.
ReplyDeleteDespite the possibility of variations in gene expression between races accounting for the athletic dominance of Kenyans in regards to running, environmental factors are the more influential factor in the GxE relationship. As Shenk notes, “there is little unequivocal evidence in support of a specific genetic variant with a major gene effect on a relevant performance phenotype” (303). The argument is further enhanced upon claiming that the more complex a physical trait is (and motility is an extremely complex process, requiring the interaction of many muscles and tissues), the more removed any single gene is from direct instruction (26). Compiling this evidence with the fact that gene variation between races is extremely minimal, the primary impactful distinction between Kenyans and Caucasians in terms of running capabilities is environmental factors.
Variations in environmental influences, most significantly during critical periods of development (prenatal, childhood, and adolescence), are extreme when comparing Western society to African society (304). The cultural distinctions between the two vastly separate societies in regards to diet, competitive will, and physical training are the primary accountants for the disparity in running capabilities between Kenyans and the rest of the world. Even Entine, who argued that genetic distinctions between Kenyans and other races could account for “a fraction-of-a-second advantage to people of African ancestry” (307), admits that it is the difference in environmental and cultural factors that causes the disparity. The physiological ability of running is thus a major exhibitor of an organism’s interdependence in nature. The interaction between genes and external stimuli (in this case physical training and diet) results in the degree to which the physiological phenotype of running can be expressed efficiently.
Nick Sotos (nsotos13@gmail.com)
As Shenk explains in on page 107, “Genes do not directly cause systems, they merely influence them” (p. 107). Essentially, he is saying that it is not solely genetics that have a large impact on the superiority of Kenyan sprinters. He cites factors such as high-altitude training and mild year round climate, but also explains that, “Kalenjin kids tend to run run long distances as a practical matter, an average of eight to twelve kilometers per day from age seven” (p. 105). Therefore, running is actually a daily part of their lives and they must be able to run in order to survive and reproduce. Thus, the reason for the Kenyans being superior in long distance running events is largely in part of environment. Clearly, running eight to twelve kilometers is not the daily routine for most Caucasians. Similarly, Caucasians have much more opportunity in terms of sport whereas in the Kalenjin tribe, “running is all” (p 105). Kalenjin boys can either make large sums of money by being successful runners or not. This provides more incentive for these children compared to others. Coaches, while not the key ingredient, also add to the environment of the Kenyan runner’s. Shenk explains that they are able to “train their athletes to the outer limits of endurance” (p. 106), simply due to the sheer volume of young boys interested in the sport. Thus, it seems as though the environment plays a huge role in not only instilling running as a lifestyle from a young age but also allows coaches to train the young boys much more rigorously than Caucasians.
ReplyDeleteIn response to Kate Berg, although “all human beings are descended from the same African ancestors” (p 304-305), there has clearly been a genetic variation since our first African ancestors. Although, as Nick points out there is not a large amount of genetic variation, as we learned in chapter 12, the process of meiosis ensures that offspring are genetically different from parents. In regards to the overall biological theme of Continuity and Change, we know that “like begets like, but not exactly as mutations and sex generates new genetic combinations” (C.O.B p 24). This explains that although we are all descended from the same African ancestors there is clearly some variation. Shenk explains these differences, in his section about how Jamaicans and most Europeans have a higher percentage of individuals ACTN3, which helps muscles worker faster. Thus, while Nick points out that genetic differences are minimal it is important to note that these small differences do occur in populations and can provide an advantage to athletes. Overall though, Nick is right in saying that the environment is a large factor explaining why Kenyan runners from the Kalenjin tribe are superior runners even though they share the same ancestors as Caucasians.
Bob Young’s view on the importance of training is accurate to a certain extent, because he seems to believe that genetics do not play a role in superior athletic ability. As an article in Sports Illustrated explains, “One study found that when people habitually lifted weights, a gene that codes for a muscle-growth-inhibiting protein became less active” (http://sportsillustrated.cnn.com/vault/article/magazine/MAG1169440/9/index.htm). They go on to explain that rigorous activity can have an effect on the epigenome and change it. It is important to note that this change is as a result of the environment. Finally, as Entine himself admits, “the individual’s work ethic, competitive spirit, and training remain the key to success” (p 307). Although, I disagree with Nick on the extent to which genes play a role in athletic ability, I agree that the environment is the determining factor in the athletic success of an individual.
PART ONE
ReplyDeleteI believe that the differences between ethnic and geographic groups in terms of athletic achievement or other things are largely due to environmental factors. The major influence is the culture one is brought up in and their environment. As mentioned, Kenyans used to run miles to school every day from their farms and they would cattle-raid and all this helped develop their speed and endurance. A lot of people’s success must also be attributed to dedication and determination. When comparing this Kenyans to American runners or other Caucasian runners, this is a generalization, but the Kenyans had to work very hard since birth since they were still in an agriculture society whereas the American and Caucasian runners were probably surrounded by a more advanced society and were able to self-indulge more and needed to work less hard. The “differences that could give a fraction-of-a-second advantage to people of African ancestry” (307) could be due to the different environment and gene interaction before birth and during development. For example, some people have a higher number of fast-twitch fibers and compared to slow-twitch and vice versa.
Since environmental factors play a crucial role in one’s success, we should heed Shenk’s words and follow some of his advice on how to positively influence children. Shenk tells us that children should be spoken to early and often, they should read early and often, they should be encouraged and given lots of praise, high expectations must be set for them and they must be able to embrace failure. Shenk says that “children develop only as the environment demands development” (47). These things are examples of external stimuli or environmental factors that can greatly influence and individual and account for their success in the future. Also Shenk says that a studied proved “that the more a person believes that abilities can be developed, the greater the success that person will eventually enjoy” (48). This means that kids shouldn’t be told that others have innate talent or that other people are geniuses; instead, children should be told about the brain’s plasticity and that the children can improve so much and be successful in the future.
I agree with Nick’s point that even if the genome of the human race is supposedly constant, there can be some differences amongst ethnic groups due the coding of certain proteins that provide an advantage. Such advantages can be a different composition of fibers as well. Gene expression and sequence of nucleotides can account for the differences between ethnic groups. According to Sid Dash genes do play a role but environmental factors account for most of the differences observed between ethnic groups and I would also agree to this.
An article called “Orangutans More Genetically Diverse than Humans” says that “The average orangutan is more diverse-genetically speaking-than the average human”. However, “the human and orangutan genomes are 97 percent identical”. This just shows how genetically similar we humans are despite our notions that we have so much variation of traits within our species. Another article poses a plausible explanation for human’s vast genetic similarity. This article called the “Explosive hypothesis about humans’ lack of genetic diversity” states that the Toba volcanic eruption that happened In Indonesia 75,000 years ago killed out so many people that the only people who survived were so alike and shared the same DNA. Some other devastating events like this had occurred in other species such as cheetahs and cheetahs are also very genetically similar.
Nikitha (lakshmi_nikitha_1@yahoo.com)
PART TWO
ReplyDeleteThe whole impact of genes on individuals relates to the biological theme of Continuity and Change as it relates to DNA. Even though all human’s genome is pretty much the same, the notion people have that there is a lot of variation arises from the knowledge people have about the way genes are created. Variations can result from mutations, the transcription process, translation process, or by gene expression. Transcription is “the synthesis of RNA under direction of DNA” (Campbell 328) and translation is the “synthesis of a polypeptide, which occurs under the direction of mRNA” (328). There are numerous steps in the transcription and translation process and if even one of the steps go wrong and a different nucleotide is in place of one that should’ve been there, this can create an entirely different protein.
Overall, there is evidence to prove that humans are not that genetically different from our African ancestors and that our genomes are quite similar. Yet genetic differences do and can exist between different ethnic groups.
http://news.wustl.edu/news/Pages/21774.aspx
http://science.kqed.org/quest/2008/03/17/explosive-hypothesis-about-humans-lack-of-genetic-diversity/
Nikitha (lakshmi_nikitha_1@yahoo.com)
Kenyans being strong runners is another example of GxE. Shenk writes, “All humans are descended from the same African ancestors...there is ten times more genetic variation within populations than between populations” (106). This proves that different races across the world have similar genomes. So, what makes Kenyans better at track and field activities? Their environment. The situation the Kalenjin live in is very different from the one that American athletes come from. First of all, the Kalenjin have a century long tradition of cattle raiding, which allowed him to have more wives, and thus more children. Kalenjin had a “phenomenal reproductive advantage that caused a significant shift in genetic makeup” (103). Secondly, Kenyan children had to run to school and back, “an average of eight to 12 kilometers per day” (105). It was a necessity that the Kenyan children had to accomplish. Lastly, running provided “a rare economic opportunity to catapult oneself into Western level education and wealth” (105). Americans didn’t feel the life changing experience with prize money, whereas Kenyans could completely change their lives and live comfortably for generations to come. Also, as Shenk states, “Success begets success”. Long tradition of success among Kenyan athletes has motivated future athletes to outperform and train to their hardest.
ReplyDeleteTo make an Olympic participant, along with skill, one must have enormous amounts of motivation and dedication. Steve Murphy, a sports psychologist tells the American Psychological Association that, “you need to have physical abilities to excel in a sport and speed, strength, endurance and coordination are vital. But determination is also a huge component of success. You have to love what you do in order to put in the roughly 10,000 hours of deliberate practice that Anders Ericsson’s famous research indicates is needed to become an expert.” Even if the skills, talents and environment are identical among athletes, the performance won’t still be the same. Psychological factors that affect performance cannot be replicated among athletes, creating different performances for each athlete.
David Shenk cites evidence that human genome is similar. This can be proved because, “the random nature of fertilization adds to the genetic variation arising from meiosis” (259). Crossing over during Prophase I adds to genetic variation. Mutations arising from sexual reproduction also does the same. Although there are differences between people, on a large scale, human genome remains largely similar.
http://www.apa.org/news/press/releases/2010/02/olympic-athlete.aspx
Rohan Dasika (rohandasika@gmail.com)