Anthro2 - 2/19/2008 9:30:00 AM Chapter 5: 8 Million Years...

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19/02/2008 10:30:00 Chapter 5: 8 Million Years of Human Evolution Outline - Macroevolution and the process of Speciation Formation of a new species Species concept is fuzzy -- Speciation in Fossil Record Only Phenotype in fossil record Genotype someday  - Hominid Evolution - Human Evolution anatomically Modern Peoples and the Upper Paleolithic - The Modern Human Origins Debate Speciation Inferred in fossil record when species changes over time or different forms  appear Anagenesis (evolution within species) o Sustained shift in populations average characteristics o May lead to speciation from ancestor population o Factors: Random mutation, gene flow, natural selection, genetic drift Genetic Drift: random changes in the gene pool, population  bottleneck, gamete sampling, founder effect
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Cladogenesis (evolution into more than one species) o An ancestral population gives rise to two or more descendent  populations (branching) Gamete Sampling - Genes are passed to new generations in frequencies unlike those of past  generations - Recessive genes not masked Founder Effect - Fission of a population from leads to two or more genetically distinct  separate populations Speciation in Fossil Record Rapid change or slow Transitional forms show both Darwinian Gradualism Speciation through adapation (long periods of transition Punctuated Equilibrium Stephen Jay Gould and Niles Eldredge:  Macroevolution occurs via long periods of stability or stasis punctuated by  periods of raped change. Hominids Bipedalism preceded brain expansion, and played a pivotal role in setting “us”  apart from the apes.  Piltdown Man (fraud) 1912 Sussex England
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Big Brain Ape Jaw 1950’s hoax uncovered (but many were already skeptical) Piltdown Exposed prejudice and preconceived notions about huyman evolution A lesson learned Bipedalism Why? o
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Anthro2 - 2/19/2008 9:30:00 AM Chapter 5: 8 Million Years...

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