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My essay on evolution, please comment

  1. Nov 8, 2006 #1
    Note that I kind of subscribe to Dawkins' model. Also, the location of the file is at http://students.washington.edu/achen89/4_evolution2nddraft.doc. I can receive e-mail at hemaalpha@gmail.com. Thanks!

    Evolution is a comprehensive biological theory that draws much of its support from many biological fields, a theory challenging humanity’s uniqueness. Much of its most modern form is traced to Darwin, however, Lamarck, who preceded Darwin, proposed a theory of evolution based on acquired characteristics, or on the parents passing off to their offspring characteristics that the parents acquired during their lifetime. Darwin, however, proposed the model of natural selection, the notion that species evolve by means of possessing inherent characteristics that resulted in an improved ability to pass on such characteristics to the next generation. Since the pronouncement of the theory of natural selection, newfound evidence in biology has only contributed to the oeuvre of support in favor of natural selection. What came as a random assortment of observations was finally merged in the “modern synthesis,” which integrated discoveries from paleontology, taxonomy, biogeography, and population genetics. The “modern synthesis” helped nullify all mainstream scientific opposition to evolution, although it also redefined evolution as a mutation in an organisms’ genome that may be passed along to future generations should the organism live to reproduce. Some scientists, like Richard Dawkins, have proposed a model of natural selection based on genes, rather than species, that nonetheless help to support the prevailing idea of evolution in terms of natural selection in organisms.

    A Darwinian model of genetics has the interpretation that undirected variation in an insulated genetic pool is acted upon by selection of its phenotypic consequences (its resultant organisms). In other words, the “fittest” genes are the ones that have the most evolutionarily fit phenotypes that manage to perpetuate the genome to future generations that may share a similar genome. In fact, several ambiguities in a macroscopic model of evolution can be resolved by turning to genetics. For example, coyotes can interbreed with both wolves and dogs, and produce fertile offspring, throwing the traditional definition of a “species” astray. However, once scientists resort to DNA to explain natural phenomena, differences between individual animals can be explained by differences in individual genotypes, with no firm dividing line to demarcate speciation.
    While Darwin doubted that humans have opportunity to live long enough to document any effects of macroscopic evolution in their lifetimes, there is now evidence suggesting that evolution does occur on such timescales. The example of bacteria developing antibiotic resistance is one of the clearest indicators of Darwinian evolution. Bacteria that develop antibiotic resistance have nearly identical DNA to those of bacteria without antibiotic resistance, with the exception of one codon, a case of mutation. Once a person infected with a bacterial illness receives antibiotic therapy, the mutated bacteria become the most evolutionarily fit ones. Through biotechnology, particular genes from completely different organisms can be attached to the genes of other organisms. Specific segments of bacterial genomes, for example, can be recombined with the genomes of farm crops to produce crops with desirable characteristics, such as insect resistance. This establishes the commonality of DNA as the unit of replication and phenotype design between different species.

    One of the arguments against evolution lay in gaps in the fossil record. This argument can be refuted by the punctuated equilibrium model –species are often in long periods of static equilibrium, followed with spurts of rapid change, especially when presented with a challenging new environment – environments that the Earth did not hesitate to throw out. Consequently, the amount of time for fossils of in-between species to accumulate is far less than the amount of time for fossils of species that stayed static for longer periods of time. Another argument lies in the notion of “irreducible complexity” –complex structures like the eye could not have evolved from nothing. Such an argument come from those who do not understand evolution, who do not understand that structures like the eye could be the process of a common structure among many organisms that has grown in complexity from the light sensors of flatworms to the complex structures that vertebrates possess. Such common structures are often known as genetic homologies, which are DNA sequences of genes that produce proteins nearly identical in amino acid sequence. The Aniridia gene found in humans and the eyeless gene in fruit flies, which code for a similar structure for both organisms, happen to be over 90% identical in both organisms. This genetic homology also happens to be found in all organisms that share a common ancestor with both fruit flies and humans.

    While the evidence behind evolution is overwhelmingly positive, scientific interpretations of it still differ. Since the arguments behind evolution lie in scientific arguments, most people who have never been exposed to scientific arguments will fail to be convinced by the overwhelming evidence in favor of it, which is not particularly surprising. While evolution can only be a theory at best, so are the majority of other scientific hypotheses, for empirical observations can only land at theory, not fact. A scientific theory must be falsifiable. Evolution can be falsifiable, but there has been no evidence that suggests that it is so. After all, why would people who believe in the scientific method have any advantage in genetic fitness?
     
    Last edited: Nov 8, 2006
  2. jcsd
  3. Nov 13, 2006 #2

    Phobos

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    Some quick, hopefully constructive comments...:smile:
    but that's not the goal of the theory.

    There were others besides Lamarck too.

    You may want to clarify this.

    Only? Theories are the ultimate goal of science. And as pointed out elsewhere, evolution is both a fact (gene frequencies do change) and a theory (an explanation for how it happens and what the history has been).

    It seems you are suggesting that a theory is a hypothesis. They're different things.

    see above. Note, observations can also be used to formulate laws and to generate new hypotheses.

    the theory of evolution _is_ falsifiable (there are tests you can do to verify hypotheses & the theory itself) but it has not been falsified.

    :confused:
     
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