Biological Anthropology Week 2
Biological Anthropology Week 2 Anth 1001
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This 4 page Class Notes was uploaded by Aafreen Afzal on Thursday January 14, 2016. The Class Notes belongs to Anth 1001 at George Washington University taught by Shannon C. McFarlin in Spring 2016. Since its upload, it has received 56 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 01/14/16
Class 3 Lecture Notes Darwin, Wallace and Natural Selection ➔ Erasmus Darwin (1731-1802) [Charles Darwin’s Grandfather] ◆ Charles Darwin’s grandfather ◆ Naturalist and poet ◆ Wrote about evolution also ➔ Charles Darwin (1809-1882) ◆ Was interested in natural stuff since childhood ◆ Wealthy family with strong connections to intellectuals ◆ Father sent him to medical school and there, he got introduced to ideas of evolution ◆ Didn’t like medical school and instead went to Christ College to pursue Theological studies ◆ Darwin’s voyage on the HMS Beagle (1831-1836) where Robert FitzRoy was the captain ◆ Darwin saw environmental diversity as well as diversity among animals ◆ Experiences that influenced Darwin’s thinking ● Observation of diversity of flora and fauna on his voyage aboard HMS Beagle ● Experience of an earthquake while in Chile ● In Argentina, Darwin collected fossil bones of extinct animal forms (e.g. extinct giant sloth, South American tree sloth) ● Interested by why some species mated and others did not ● Observation of diversity in ground finches across the Galapagos Island, looked and behaved differently from one another. ● 13 different varieties of ground finches with certain similarities and differences, mostly in the size and shape of their beaks were the differences. (shorter beaks ate insects, etc.) ● He theorized that all the finches must have descended from one ancestor who may have visited the islands. ● His reading of Thomas Malthus “Essay on the Principle of Population.” “Human populations have the ability to increase exponentially, at a faster rate than food production. There is a struggle for existence.” Darwin’s conclusion: Individuals of a species with particularly advantageous characteristics (adaptations) would be more likely to survive in limiting conditions and would thus reproduce more successfully than individuals with less advantageous attributes. ● Also influenced by the observation of the power of artificial selection by plant and animal breeders. ○ Artificial Selection of Dog Breeds ➔ Darwin’s return from the voyage (1836) ◆ Married Emma Wedgwood, first cousin ◆ 1844: Darwin prepares his first lengthy “sketch” on his theory of evolution by means of natural selection ◆ 1858: Darwin receives a manuscript, in which Alfred Russel Wallace had independently conceived of evolution by means of natural selection. ◆ 1858: Darwin and Wallace present their ideas to the Linnean Society in London, detailing their proposed mechanism for evolutionary change. ➔ “ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION” - CHARLES DARWIN (1859) ◆ Main themes: ● Biological evolution is fact ● Common descent, with modification ● Gradualism: Differences between organisms evolved by small innumerable steps through many intermediate forms ● Natural selection is the mechanism of evolution Observation: Species produce more offspring than can be supported by available food resources. Deduction: Limited resources lead to competition between individuals of a species. There is a “struggle for existence” (inspired by Malthus Observation: There is a biological variation among individuals of a species. The characteristics of some individuals appear more favorable adapted to their environments than those of others. Deduction: Differential survival and reproduction of those individuals with more favorable or advantageous traits. This leads to greater fitness. Deduction: Individuals who possess favorable traits contribute more to the next generation. As favorable traits are inherited by their offspring, they become more common in the population over time. (e.g. Giraffes who crane their necks to reach leaves higher on the tree, end up passing the traits along and giraffes’ necks grew longer and longer over time) ● Adaptation: Changes in response to new or varying environmental pressures ○ Occurs in response to particular environmental conditions ○ Geographic isolation may be a force in the origin of species ○ Diversity observed among species is the result of evolutionary relatedness (time from common ancestor) and adaptation -----> Descent with modification ➔ Examples of Natural Selection at Work ◆ Changes in pigmentation among Peppered moths near Manchester, England ◆ Pre-Industrialization - 99% light gray. 1% dark. Provides effective camouflage to the light coloured moths so they are not susceptible to becoming preys. ◆ Medium ground finch on Daphne Major, Galapagos Islands (after a year of very little rain, the beaks became larger in order to eat larger seeds, instead of their preferred type which was small seeds consumed by their smaller beaks) ◆ 1982 El Niño event (small seeds abundant) + Large ground finch (competitor) arrives on the island ◆ Medium ground finch (G. Fortis) ◆ Large ground finch (G. magnirostris) More efficient at processing large seeds. ◆ Species are not fixed types but are capable of change over time ➔ Revolution and Reactions to Darwin’s book ◆ “Descended from apes! My dear, let us hope that is not true, but if it is, let us pray that it will not become generally known” - Wife of the Bishop of Worcester ◆ “Light will be thrown on the origin of man and his history” - Charles Darwin (1859) ◆ Thomas Huxley (1863) “Evidence as to Man’s Place in Nature” responded positively ◆ Life began in AFRICA.
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