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McGill University
ANTH 203
Michael Bisson

Religious beliefs about human origins have served as both a guide and justification for human actions Humans were considered separate from the natural world but evolution connected humans to the natural world thMid 18 Century Linnaeusclassification of plants and animals places humans in the order Primates At first Progressionism and Natural Theology attempted to fit biology into a religious frameworkProgressionism is the stair theoryeverything is working towards Gods image and is on a different step This was racistly used to rank people in the western world FIRST systematic evolutionary theoryJEAN LAMARCK Based theory on the inheritance of acquired characteristicsAcquired characteristics means that your children will inherit things that you have acquiredcan be proven wrong because if you cut off your hand your children will still have two Evolution had little impact until genetics was explainedBig problem for early evolutionists was the 6000 year biblical timespan which did not allow time for evolution to occur The emerging science of geology challenged this short chronologyCharles LYELL publishes Principles of GeologyThis promoted uniformitarianism the idea that the earths form was derived from SLOW and GRADUAL processes of uplift erosion and deposition This contradicted catastrophismearth forms all created by cataclysmic floods volcanic eruptions etc Charles Darwin became a biologist and was appointed ships naturalist on the Beagle for a survey of the coast of South AmericaDarwin went ashore and collected at every opportunity This gave him a North to South then South to North transect where he could observe geographical variation in related species AND the link of that variation to environmentaldifferencesThis refined his concept of ADAPTATIONDarwin strongly influenced by Essay on Population by Thomas Malthus Struggle for existence in which more offspring are born than can survive to reproduce 5 MAJOR POINTS OF DARWINIAN EVOLUTIONARY THEORY 1Organisms produce more offspring than can survive to reproduce 2Because numbers of individuals in a species are usually constant there must be a high death rate 3Individuals in each species vary in their characteristics 4Variants that fit their environment better will be favored over those less fitFitness is defined by DIFFERENTIAL REPRODUCTIVE SUCCESSBy inheritance better fit individuals pass on their beneficial characteristics in greater numbers because they have more offspring that survive and reproduceThis process is natural selection 5Following generations will continue to exhibit and refine adaptations realized by their ancestorsThis left 2 major unanswered questions A What is the source of individual variationB How are characteristics inherited Alfred R Wallace develops the same theory from his work in Southeast Asia Darwin publishes Origin of Species in 1859 causing great controversyScientific challenges to Darwinian Theory stressed his inability to explain inheritance and his reliance on a long age for the earth Darwin believed in blending inheritance where characteristics from each parent mixed like liquids so if you had one parent with light eyes and one with dark your eyes would be somewhere in the middleThis was a crucial flaw The major scientific challenges were 1Fleeming Jenkin1867showed statistically that with blending inheritance single favorable mutations would be diluted out of existence over time making Darwins natural selection impossibleRealizing Jenkin was right Darwin reverted to Lamarkian explanations of inheritance undermining his own theory2Lord KelvinArgued that the universe was governed by chemical reactions and had a short history His paper claimed that the time that the earth took to cool to its present state was as short as 20 million yearsHis prestige caused geologists to reduce their estimated age of the earth leaving no time for gradual evolutionary processes Evolutionary theory rehabilitated by 2 discoveries 1In 1900 biologists discover the work of Mendelfoundation of modern geneticsThis reestablished natural selection as a viable process 2Pierre Curie and Albert Laborde discover atomic energy in 1903 making Kelvins age estimates for the earth meaningless Religious opposition to DarwinMany early evolutionists thought evolutionary theory should replace religion as a guide to moral behavior Religious progressives like William Jennings Bryan strongly opposed evolution because they thought it would replace morality and ethics with a Law of Hate These concerns were legitimateMany supporters of evolution had adopted two VERY problematic ideas that mirrored their own class and racial biases 1Unilinear EvolutionismThought evolution was directed toward the production of Western rdcivilizationConsidered 3 World peoples to be living fossils inferior to Europeans who were naturally more intelligent and moralJustified colonialism to uplift native peoplesAtavisms ie throwback primitive traits used to explain European crime etc 2Social Darwinismthe Eugenics movementSocial Darwinismconcept of survival of the fittest justifies exploitation of the weak by the strong Eugenics movementattempts to prevent inferior peoples from breeding Ultimate expression of these ideas was Nazism thSo UNLIKE today many 19 Century opponents of evolution were humanists and progressives who believed that evolution was simply a scientific cover for vicious social ideas BUT these ideas distort the real meaning of evolutionary theory Darwin and others realized that fitness could result from cooperation as well as competition Evolution describes biological processes and does NOT provide a guide for moral or ethical behavior which are cultural constructs Neanderthal fossil discovered in 1854 by quarry workers Dismissed because scientists expected early humans to have a humanlike head on an apelike body they thought large brains evolved firstEugene Duboisdeliberately looked for early humans in Java he thought humans were descended from orangutansFound skullcapfemur near Trinil Named Pithecanthropuserectus now Homo erectus Dismissed for the same reason as Neanderthal Piltdown fraudCharles Dawson finds modernlike cranium with apelike jaw near Piltdown England in 1912 Because it corresponded to expectations this fake was not exposed until the 1950s Canadian Davidson Black finds Peking Man near Beijing China in 1927 Similar to Dubois Pithecanthropus fossils Raymond Dart finds the Taung Baby in South Africa in 1924 Named Australopithecus africanus Claimed humans originated in Africa not EurasiaSkeptics argued it was a baby chimpLouis and Mary Leakey find Australopithecine fossil in Olduvai Gorge Tanzania in 1959 Crude stone tools directly associated with the fossil Date of 192 million years BP MYBP doubles the estimated age of the human line and validates Darts claim of an African origin for humansGregor MENDELPublishes Experiments in Plant Hybridization describing his particulate theory of inheritance Was ignored for 35 years because most biologists couldnt understand probability statisticsTraitany physical characteristic of an organism GenesThe physical structure that transmits hereditary potentialNow defined as a segment of a chromosome that produces a recognizable effect and separates as a unit during the formation of sex cells gametes Genes can have alternate forms that produce different effectsallelesPhenotype is the product of the genotype and influences of the environment Mendels Law of SegregationAlleles separate during the production of sex cells This contributes to phenotype variationIndependent assortment of geneseach gene at a single location on a pair of chromosomes one chromosome from the father the other from the mother is equally likely to be transmitted when sex cells are formed SOURCES OF VARIATION1Mutationrandom changes in the DNA molecule This is the only source of truly NEW genetic variationMutation can occur in individual genes or in entire chromosomes through either numerical ie adding or deleting an entire chromosome or structural changes ie addition of a segment loss of a segment reversal of a segment etc most mutations are neutral and dont affect the phenotype2Recombinationthe creation of new genotypes resulting from segregation and the exchange of genetic material between paired chromosomes during sexcell formation meiosis SPECIESAny group of organisms which can interbreed to produce fertile offspring This corresponds to the biological species concept Species may be one contiguous population or be separated by barriers into subpopulationsMendelian Populationa population in which genetic material is actually being exchangedOften equivalent to subpopulationsGene poolAll of the genes in a Mendelian population
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