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evolution.doc - LECTURE 2 : EVOLUTIONARY THEORY...

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LECTURE 2 : EVOLUTIONARY THEORY Introduction All the ideas that we will be exploring in this course are based on the idea that the physical and behavioral capacities of humans have evolved through the action of natural selection on ancestral populations. Not only is it true that we have the physical features we do because in the past those features were advantageous, but also all of our basic desires and motives are programmed into our brains because individuals with those desires and goals in the past left more descendants. The specifics of our cultural environment determine how we can best reach those programmed goals. Imagine what would happen, for example, if a human variant arose that was indifferent to danger. Such an individual would not avoid danger, and would soon be killed leaving no descendants. The genetic basis for such indifference would disappear and only those who were motivated to avoid danger would continue to exist. This type of selection is the reason that all humans are motivated by food, sex, social status, and avoid illness, injury, death, suffering, etc. There will never be any culture in which members do not share some of these basic goals with the rest of humanity. Our brains are not blank slates that culture can write upon, in whatever whimsical fashion it desires. Instead brains are a bundle of hard- wired goals, desires and preconceived interests that have all been produced by selection in past generations. There will never be an ethnic group that eats rocks and there will never be one where members are unconcerned about their social status. We like the taste of sugar because those humans who ate sugary foods in the past left more descendants than those who did not seek out sweet foods. We want to achieve high social status because those who did so in the past left more descendants than those who did not try to achieve high status. The theory of evolution by natural selection was first posited by Charles Darwin in 1859 in a book called On the Origin of the Species , although his ideas on natural selection date back to at least 1838. Darwin was basically interested in answering two big questions about the diversity of life on Earth: 1) why are their so many different kinds of plants and animals and why do some look like others (and like humans)? 2) why do plants and animals appear to be so well adapted to their environments? Eg. all these structures are derived from basic mammalian forelimb but each is highly specialized for a particular way of life. flippers of seal lions, Wings of bat , Claws of anteater \\
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The answer to both these questions came in the form of his THEORY OF EVOLUTION BY NATURAL SELECTION. Darwin was caught up in the debate over whether evolution had occurred, but his main contribution was not to convince people of evolution but to explain how evolution happened. Evolution is a change in form through time with earlier forms leading to later ones . Many biologists including Darwin’s grandfather, Erasmus, believed that animals
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This note was uploaded on 03/01/2011 for the course ASB 194 taught by Professor Hill during the Spring '11 term at ASU.

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evolution.doc - LECTURE 2 : EVOLUTIONARY THEORY...

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