In Chapter 13, Shenk addresses Lamarckism, the, "flimsy idea that biological heredity can somehow be altered through personal experience." (155) After the emergence of Darwin's theory of evolution, this concept of Lamarckism was pushed aside and deemed naive and crude. However, with the recent discovery of epigenetics in the last decade, Jean-Baptiste de Lamarck's theory did not seem as unreasonable. Epigenetics is based on the theory that the histones around which DNA is packaged can affect and change gene expression, and such changes can be inherited by future generations. As Duke University's Director of Epigenetics and Imprinting, Randy Jirtle, says, "everything we do - everything we eat or smoke - can affect our gene expression and that of future generations. Epigenetics introduces the concept of free will into our idea of genetics." (160)
In your response, address the following: Will the recent discovery of epigenetics derail Charles Darwin's theory of evolution for both scientists and the public? Which theory should be considered more 'legitimate'? Would the human race be able to purposefully tailor the progress of future generations with the help of epigenetics? To what extent?
(Adithi Rao, adithi.a.rao@gmail.com)
In your response, address the following: Will the recent discovery of epigenetics derail Charles Darwin's theory of evolution for both scientists and the public? Which theory should be considered more 'legitimate'? Would the human race be able to purposefully tailor the progress of future generations with the help of epigenetics? To what extent?
(Adithi Rao, adithi.a.rao@gmail.com)
Evolution is the idea that organisms have been changing to fit different functions, but all stem from the same ancestor. In terms of human evolution, it is believed that humans evolved from primates, and are still evolving and adapting to their environments. (http://www.pbs.org/wgbh/evolution/educators/lessons/lesson5/index.html). Although Darwin’s natural selection is crucial to our understanding of evolution and the scientific paradigm of the modern age, a fraction of Lamarck’s theory has resurfaced due to the recent discovery of “epigenomes-the packaging that surrounds DNA” (Shenk 158). The basic outline of Darwinism comes from the idea that random mutations and natural selection drive the survival of the fittest, and that “populations evolve by changes in gene frequency brought about by random genetic drift, gene flow, and especially natural selection” (Shenk 345). Natural selection is defined as “a process in which individuals with certain inherited traits leave more offspring than individuals with other traits” (Campbell 456). Both Lamarckism and Darwinism describe the conception of species among a “population of inbreeding individuals with similar characteristics” (http://sciencenetlinks.com/student-teacher-sheets/lamarck-and-darwin-summary-theories/). However, in Darwinism, there are frequent variations, in which natural selection takes place. Lamarckism, on the other hand, describes how the characteristics of an individual can be passed down because of “the influence of the environment in which their race has long been placed…[and] the influence of the predominant use or permanent disuse of any organism” (Shenk 344). While this part of Lamarck’s theory remains flawed, the ability for an individual to change the traits passed down generation to generation can change because “lifestyle can alter heredity” (Shenk 161). The only significant part of Lamarck’s newfound significant data was the fact that individuals do have an active way of changing their traits to be passed down to new generations, and the idea that “biological heredity can somehow be altered through personal experience” (Shenk 155). Darwin’s theory of evolution is already universally accepted, and the newfound evidence of epigenetics can be used to enhance Darwinism, not challenge it.
ReplyDeleteFurthermore, epigenetics can only qualify Darwinism because Darwin’s main ideas in The Origin of Species included “that descent with modification explains life’s unity and diversity and that natural selection brings about the match between organisms and their environment” (Campbell 457). The discovery of variations in epigenetic material contributes to the variation among populations, which isn’t directly related to mutations. Because of genetic variation within populations, “no two individuals have the same DNA sequence, with the exception of identical twins or clones” (http://www.actionbioscience.org/evolution/lenski.html). Because genetic variation is so prevalent in populations, it proves that species have been evolving over time, and epigenomes support Darwin’s argument. While little is known about epigenomes, Shenk describes that individuals have the power to influence genes for future generations; for example, “a twelve-year-old kid could improve the intellectual nimbleness of his or her future children by studying harder now” (Shenk 161). Epigenomes add to the theory of evolution, and could eventually cause an entire species to evolve, as humans evolved long ago. With the concept of altering epigenomes specifically to pass down to new generations, it could be possible to have the entire human race become more intelligent or athletic (or any other trait) in small increments over time.
Ria Singh (riasingsing@gmail.com)
*new paragraph at "Furthermore, epigenetics can only qualify..."
DeleteTo begin, evolution is defined by by http://www.biology-online.org as "genetic variation [driven by] natural selection as individuals with advantageous traits are more likely to reproduce successfully, passing these traits to the next generation, which is called adaptive evolution." This is Charles Darwin's idea and it occurs over millions of years; however, recent research shows that Lamarck's theory, while very loosely worded, is not entirely flawed; in fact, it creates the foundation of epigenetics, or genetics influenced by the environment - GxE and how "the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down to at least one successive generation" (http://blog.tutorvista.com/2010/12/epigenetic-possibilitiesgenes/). With the discovery of epigenetics, Darwin's theory of evolution is not derailed, but instead has more conditions to be added on to its definition. Epigenetics has ties to evolution because of how the environment can affect natural selection, the bell curve, and organisms; as seen with Lamarck's giraffe example, certain organisms are shown to survive in an environment because of a desirable trait (in this case, long necks), that allow them to survive and reproduce. With an application to humans and the modern world, evolution is still occurring; however, it is how we perceive it and how our "environment" is considered "normal" to us that we fail to notice how epigenetics throughout time affects human development. (Also because 100 years in our opinion is long, but we won't see much change in humans because of how evolution occurs over millions of years.) In addition, Randy Jirtle, who stated, "everything we do - everything we eat or smoke - can affect our gene expression and that of future generations. Epigenetics introduces the concept of free will into our idea of genetics" is correct as seen through the research of Dr. Lars Olov Bygren of Sweden's Karolinska Institute in Stockholm (106).
ReplyDeleteSimple biology would lead some to believe that genetics was simple: the crudest idea was from Mendel's pea plants where mom + dad = offspring that could possess heterozygous, homozygous dominant, or homozygous recessive genes depending on the parents' genes. As more information was presented, the G+E model was born where genetics provided one with a good brain or other traits, and the environment could have a smaller effect later. Even with the growing idea of GxE, people still believe that whatever choices they made during their lives could ruin them such as with short-term memory, health issues like obesity, or even quicken death, but that it wouldn't change one's genes — the DNA that is set in place in accordance with the HOX genes that turned on and off to form the basic human. People believed that their actions wouldn't affect their children because they would be a "blank slate" that started fresh with some genes from them and their spouse - the rest would be up to nature to decide as to whose eyes would the child have and what hair color.
(Diana Liao, dianaliao3@gmail.com
"In 1986, for example, the Lancet published the first of two groundbreaking papers showing that if a pregnant woman ate poorly, her child would be at significantly higher than average risk for cardiovascular disease as an adult" (http://www.time.com/time/magazine/article/0,9171,1952313,00.html). In addition to that research, Bygren also discovered in an experiment with 14,024 fathers whom smoked before age 11 had sons with a higher body mass index at nine years old than their peers with nonsmoking fathers. The human race is already taking notes from the study of epigenetics because of the shocking realization that one's actions can affect their offspring's genetics later.
ReplyDeleteIn fact, the human race is already trying to tailor humanity's future with epigenetics as seen with the creation of the drug, Azacitidine. Approved by the FDA in 2004, it is used to treat MDS (myelodysplastic syndromes), by interfering with DNA methylation; Azacitidine silences parts of DNA and turns off genes while turning on others to prevent cancerous growths. "DNA methylation plays a crucial role in the development of nearly all types of cancer" because it promotes the rapid, uncontrolled mitosis of cells (http://www.nature.com/ng/journal/v33/n3s/full/ng1089.html). All this will tie in with regulation, also known as homeostasis, and with regards to genes, it is the modulation of any of the stages of gene expression, hence, it encompasses the various systems that control and determine which genes are switched on and off, and when, how long, and to what extent the genes are expressed (http://www.biology-online.org/dictionary/Gene_regulation. With MDS, this uncontrolled growth is caused by a mutation in the DNA, and it is difficult to deal with it with cases of MDS because it is directly in the blood stream. The error at a site can cause uncontrolled growth when mitosis occurs, which replicates more and more cells with the same mutated DNA. However, Azacitidine works by stopping cells from dividing and growing by interfering with checkpoints while directly killing abnormal blood cells. "This effect is strongest in cells that are growing and dividing very quickly, such as cancer cells, while cells in other parts of the body that divide much more slowly are relatively unaffected" (http://www.virtualmedicalcentre.com/drugs.asp?drugid=3170). After inhibiting further replication of mutated cells, the bad genes are silenced by this drug, which demonstrates the influence of the environment on genetics. In fact, Azacitidine patients live two years compared to the few months that past patients lived using other cures. Bygren and other epigeneticists hope to combat more genetic diseases like cancer, schizophrenia, autism, Alzheimer's, diabetes and many others by silencing those genes and turning on other genes to improve health. While epigenetics is still being worked out, it has the potential to help humanity overcome the idea of genetics being limiting and if that happens, it could possibly rewrite Darwin's theory of evolution since the human species can defy natural selection by prolonging life by combating genetic diseases or creating a beneficial environment for offspring.
(Diana Liao, dianaliao3@gmail.com)