The Discovery of the Theory of Natural Selection - Report Example

Natural Selection (school) The Discovery of the Theory of Natural Selection by Darwin Introduction Since the dawn of civilization, man has tried to explain his existence and the development of all living things. Various theories have been established by scholars and philosophers and these theories have established various explanations and schools of thought on the existence of man and of the universe. No theory has been as revolutionary or as controversial as the theory by Charles Darwin in his thoughts on natural selection. This paper shall discuss the discovery of the theory of natural selection by Darwin. It shall first present a summary of the scientific theories about evolution before Darwin’s discovery of natural selection. It shall also provide a description of how the discovery was made, including what was going on in Darwin’s life for him to make the discovery. It shall then present a description of natural selection in terms of the modern evolutionary synthesis of the 20th century. Finally, this paper shall also apply the principles of natural selection, explaining why we have the current problem of bacteria which has become resistant to antibiotics. Discussion Evolutionary theories were first seen with the Greek philosophers who adhered to the ideas of origination, setting forth that all things originate from water or air, and that all matters come from one central and guiding principle (Think Quest). Medieval theories on evolution were dominated by Christianity and its teachings. Immanuel Kant set forth that based on similar qualities of organisms, all organisms come from a single source. He further discussed that a chimpanzee may develop organs which he would use for walking and grasping objects, and from these organs, the structure of man may evolve and develop into a social culture (Think Quest). Carolus Linnaeus first believes in a fixed quality or nature of species; however, with hybridization, he soon found out that new species can be built from the original species. He also considers hybridization as part of God’s plan. The British Admiralty in 1831 invited a naturalist to travel with Capt. Robert Fitzroy on a voyage in the HMS Beagle to survey Patagonia, Tierra del Fuego, Chile, Peru, and the Pacific Islands. Charles Darwin was recommended to join this voyage, and he journeyed with the Beagle for five years (Vardiman). His tour of the Cape Verde Islands provided him a practical application of Charles Lyell Principles of Geology with his views of volcanoes and other geological formations. In his tour, he was able to witness massive erosion downstream coming from glaciers. He then thought that the glaciers could not have been formed the way they did if the explanations of the Bible would be believed (Vardiman). He then considered truths in the explanations of Lyell and his doctrine of uniformitarianism. He saw his first tropical rain forest in Brazil and his first fossils in Argentina. He also saw the tribe of savage men in Tierra del Fuego, then he experienced his first earthquake in Chile. He climbed mountains, he observed finchs with varying beak lengths and he travelled the Galapagos islands, Australia, New Zealand, South Africa, Brazil, and then back to England (Vardiman). His theories stemmed from his travels on board the Beagle. His initial interests were on the geological, as evidenced by his first published books. After his voyage on the Beagle, he also attempted to explain his observations on birds and tortoises on the Galapagos Island. He then went on to consider explanations and theories in relation to anatomy, embryology, and geographical distribution (Vardiman). The concept of natural selection was eventually established due to the selection pressure which he related to the ecological niches of the different species. His theory was the first to “provide evidence for evolution and to explain how the process of natural selection produces adaptation” (Vardiman). Darwin approached natural selection from various perspectives and he discussed that due to the life’s struggles, the changes from “whatever cause proceeding, if it be in any degree profitable to an individual of any species…will tend to the preservation of that individual, and will generally be inherited by its offspring” (as cited by Richards, p. 42). As a result, an offspring would also have an improved chance of surviving. Hence, the overall outcome would result to the natural selection process. The modern evolutionary synthesis of the 20th century is considered a collaboration of the Darwinian evolutionary theory and of Mendelian’s genetics theory (University of Dayton). This synthesis is based on the ideas of evolution progressing from the ancient civilization to the current modern man. Different people contributed to its development and conceptualization; however there are main contributors to its development, including Thomas Morgan, August Weismann, Ernest Myer, and George Simpson, among others. Thomas Morgan was a geneticist who set forth the mutation is seen in every generation and with every physical trait (Dayton University). This theory dismissed the notion that diversity within a population was limited and confined. August Weismann was a developmental biologist who worked on somatic cells, as well as germ lines. He observed that these cells are differentiated early during the development and they are hardly interact. Dobzhansky was a biologist who formulated his synthesis between genetics, adaptation, and biological diversity (Smocovitis, p. 127). George Simpson was a paleontologist who was able to establish the connection between paleontology, genetics, and evolutionary biology (Campbell and Reece, p. 417). The theorists Stebbins, Jr., Mayr, Dobzhansky, and Simpson are the main theorists who have made valuable contributions to the formation of Modern synthesis. Modern synthesis is based on two main ideas: that gradual evolution comes from the minor genetic shifts which are impacted by natural selection; and the origin of the species or of macroevolution can be rationalized in terms of natural selection affecting individuals (Freeman and Herron, p. 54). Based on the modern evolutionary synthesis, Darwin’s four main theories can be reformulated as follows: that due to mutation which creates new alleles, segregation, and assortment grouping into new combinations, people belonging to a grouping are variable for most traits and characteristics; that individuals transmit their genes to their children unbroken and independent of other genes; in most generations, more children are born that can survive; and those which survive and also reproduce are those which have alleles or qualities which are best fitted to their environment (Dayton University). Futuyma, (p. 12) also discussed that the main theories of evolutionary synthesis are based on various ideas including the fact that populations have genetic variations which surface at random mutation and recombination; that various individuals and populations evolve based on changes in gene frequency caused by random gene drifts and natural selection; and that diversification is based on speciation which often includes gradual changes in the reproduction isolation among various groups (Futuyma, p. 12). These processes, when allowed to persist, cause changes which warrant the implementation of higher taxonomic classifications. Natural selection seems to play a significant role in explaining the development of antibiotic resistance. Before antibiotics were introduced in the 1940s, antibiotic infections were not all that common. However, after antibiotics were introduced, their use also increased to a significant degree. But the antibiotics introduced first in the 1940s and 1950s are no longer available in the current market due to the development of antibiotic resistance to these drugs. New antibiotics have been invented and made available to the people and with each new antibiotic being introduced, resistance to bacteria became a commonplace occurrence (Haddix, et.al., p. 2). Today, the use of bacteria has changed with the health professionals trying to slow bacterial evolution; however, a clear solution to such issue has yet to be established. Scientists are still evaluating how bacteria develop in order to assist them in predicting how microbes respond to treatments in order to assist in the management of the disease (Haddix, et.al., p. 2). Antibiotics have varying actions in response to a disease and consequently, they can develop antibiotic resistance in a variety of ways. It can be developed through a change in the permeability of the cell membrane which then does not allow the entry of the antibiotic into the cell or causes the antibiotic to be ejected from the cell. This resistance can also be developed with cells acquiring the ability to inactivate the antibiotic (Haddix, et.al., p. 3). Bacteria can develop resistance to antibiotics spontaneously in a group of cells as a result of mutation; they can also develop from various microorganisms through Horizontal Gene Transfer where genes can be exchanged between unrelated bacteria (Haddix, et.al., p. 3). With one colony forming from a single cell, all cells in the culture have the same mother cell and due to random mutation differentiate them from other cells. Genetic differences in populations can therefore cause accumulation of random mutations (Haddix, et.al., p. 3). In effect, due to random mutations, some cells within the bacterial grouping will become resistant to antibiotic ampicillin. Without any pressures in selection, resistant cells will stay uncommon in the population. If there is a transfer of the culture to the media containing ampicillin, situation changes manifest because the ampicillin causes strong selective pressure which causes resistant cells to develop, but which also has a deleterious impact on cells which are not resistant (Haddix, et.al., p. 3). As a result, a dramatic increase of resistant cells in population cells become manifest. Basically, these occurrences represent the process of natural selection with natural variation in a population caused by the random accumulation of mutations and selection. Works Cited Campbell, N. & Reece, J. “Biology”. 2005. New York: Pearson Benjamin Cummings. Dayton University The Modern Evolutionary Synthesis and the History of Its Development. (n.d). 20 July 2011 from http://campus.udayton.edu/~hume/EvolSynth/evolsynth.htm Dayton University. “The Modern Evolutionary Synthesis and the History of Its Development. (n.d). 20 July 2011 from http://campus.udayton.edu/~hume/EvolSynth/evolsynth.htm Freeman, S. & Herron, J. “Evolutionary Analysis”. 2001. New York: Prentice Hall Futuyma, D. Evolutionary Biology. 1986. Sinauer Associates, p.12 Haddix, P., Paulsen, E., & Werner, T. Natural selection and evolution of antibiotic resistance in bacteria. Bioscene, 2000, volume 26, pp. 1-21. Richards, R. “Darwin’s Theory of Natural Selection and Its Moral Purpose”. University of Chicago. (n.d). 20 July 2011 from http://home.uchicago.edu/~rjr6/articles/Richards--natural%20selection.pdf Smocovitis, V. “Unifying biology: the evolutionary synthesis and evolutionary biology”. 1996. California: Princeton University Press. Think Quest. “Pre-Darwinian theory of evolution”. 2000. 20 July 2011 from http://library.thinkquest.org/C004367/eh1.shtml Vardiman, L. “The Development and Deficits of Darwins Theory”. Acts & Facts, 2009, volume 38 (2): p. 14. Read More