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Unformatted text preview: 1 Chapter 22: Decent with Modification: A Darwinian View of Life Can you read this? If you cant read this then you really ought to move to a new seat! How about now? If you cant read this then you really ought to move to a new seat! Important Point: Darwinian Evolution The material we cover in Bio 114 is very different from that covered in Bio 113, particularly in terms of the perspective and approach of those who engage in these different aspects of biology Its as though biology consists of two sciences, a reductionist science that seeks to emulate physics (113), and a philosophical science that is as interested in the subtleties of history as in the rigors of physical sciences (114) Its not that we will not be learning real science in Bio 114, but instead that our general approach toward learning will be somewhat different from that of Bio 113 In Bio 113, basically, you sought to understand how a cell works; here we will deal with such squishy topics as why it is the cells that we observe exist at all Keep an open mind and study hard and by the end of this term you will have gained an appreciation of the most important concept in biology: Darwinian evolution Charles Darwin Evolution, in its most general sense, is simply successive change that occurs over time Darwin more popularized the idea of biological evolution rather than inventing it 2 Darwinian Evolution Darwinism encompasses two distinct ideas The origin of biological diversity via evolution Natural selection as a mechanism of evolutionary change The process of evolution can be summarized in three sentences: (talk.origins) Genes mutate Individuals are selected Populations evolve Major goals of this chapter: Get a feeling for what it means for two organisms to be Evolutionarily Related Get a feeling for what is meant by Selection (a.k.a., Natural selection) and by Darwinian evolution Get a feeling for how we infer that organisms are evolutionarily related Why Darwinism? Together the tenets of Darwinism serve as the foundation of our understanding of life Any time you generalize from one organism to another (e.g., from a fetal pig to a human) you are assuming evolutionary relationship Any time you speculate on the function of a biological structure, you are speculating on natural selection (= differential reproductive success) It is difficult to imagine biology as a coherent discipline absent Darwinism In fact, biology did not exist as a coherent discipline prior to the advent of Darwinism Nothing in biology makes sense except in light of evolution 1 st Major Goal of Chapter 22 Get a feeling for what it means for two organisms to be Evolutionarily Related: Hint: It means that the two organisms are related by Blood !...
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