Anthropology fall05

Anthropology fall05 - 1 Anthropology 9.09.05 Evolution-...

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1 Anthropology 9.09.05 Evolution- non-directional Change through time- no goal Darwin: Upper middle class; theology Loved Natural Science Erasmus- Grandfather MS Beagle- 1831-1836. A boat, for a voyage. Darwin may have been invited to be the captain’s companion. Darwin was allowed to go on the trip. He carried a book by Lyle… Galapagos Islands- off NW coast of Ecuador Finches. He started studying birds. Darwin’s- evolution- descent with modification Progeny (offspring) Darwinian evolution: Simple, elegant Simple: components a. Variation- essential component b. B. Natural selection- pressures that determine: whether or not they will survive Reproduction success Examples of pressures: food source, environment, Obvious pressures: Disease Food supply Climate Predators Less obvious pressures: Territory (Birds, bears, raccoon) Ability to adapt to new territory. Adaptive advantage Reproduce at expense of others Reproductive success- survival of fittest a little misleading. . Whether you leave offspring who survive If your offspring, you are successful in terms of evolution. Why? - variability for continuing change
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2 NO MECHANISM TO PREVENT MAXIMUM REPRODUCTION CAPACITY NO GUARD AGAINST EXTINCTION EITHER EXTINCTION ACTUALLY THE RULE LESS THAN .1% OF ALL SPECIES THAT EVER LIVED ARE ALIVE TODAY! Interaction between pre-existing variation and natural selection (reproductive success) promotes non-direction change thru time. Selection operates n variability What will be passed down? Lyles’s influence on Darwin. Malthus’s influence Populations- checks and balances in nature Food supplies cannot keep up with reproduction of populations- doubling can occur ever 25 years. Impulse to multiply- checked b fierce struggle for existence in nature. (Bands of hypoplasia illustrate an interruption in growth and development. Harris lines- little white bands at the top and the bottom of the tibia. Also known as tranverse lines where the most growth takes place. In his eye organ he has little white holes called cribra orbitalia. Iron core diet.) MALTUS DEMONSTRATED TO DARWIN: SELECTION- operates on individual EVOLUTION- operates on population MEANING: small changes that accumulate and change gene frequency of characteristics eventually change populations. Through time speciation: can change. COMPONENTS OF DARWIN’S THEORY (IN TEXT) 1. Offspring production- faster than food. 2. All living things vary. 3. More born than can survive; fierce struggle. 4. Those with favorable traits survive. 5. Environmental context determines if trait is beneficial. 6. Over long periods- successful variations produce great differences- result- new species. 7. Traits are inherited (passed down). Non-directional change through time is really a change in the gene frequency from one
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Anthropology fall05 - 1 Anthropology 9.09.05 Evolution-...

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