Our Place in Nature? Historical context for ideas of Charles Darwin Charles Darwin Restless young guy! 1831: HMS Beagle Voyage of the Beagle 4 years P200 Lecture 1
Supernatural arguments Linnaeus Natural arguments Malthus & Lamarck Ussher & Cuvier Lyell Creationists: literal interpretation of Bible 1650 Archbishop Ussher 4004 BC Oct 23, 9:00 AM Catastrophists Cuvier - layers = Noah s floods P200 Lecture 2
Fixity of species C. Linnaeus (1736) Perfect designs types Taxonomy classification system: - Homo sapiens - Pan troglodytes Natural Philosophy Newton Industrial Revolution & Age of Reason God = celestial clockmaker, ultimate mechanic Universe = gorgeous windup toy Dr Pangloss (Candide) all s for the best in this best of all possible worlds Voltaire Great Chain of Being Fixed hierarchy of divine creation Racist P200 Lecture 3
Essay on Population Thomas Malthus Competition for scarce resources Struggle for existence 1798 Evolution: transformation Jean Baptiste de Lamarck 1744-1829 Theory of Acquired Characteristics Evolution = progress Organisms improve by adjusting to different environments Principles of Geology : Changing earth (Constant biology) Charles Lyell P200 Lecture 4
Super-natural vs natural explanations Catastrophists Geologists Young earth Noah s flood Geological processes - Sedimentation - Erosion Old earth Uniformitarianism Galapagos Islands Darwin collected: Varieties of animals on different islands Galapagos Islands P200 Lecture 5
Finches Cactus finch They nest in cactus; they sleep in cactus and have sex in cactus. They drink cactus nectar, eat cactus flowers and seeds. In return, they pollinate the cactus. When I see these islands in sight of each other tenanted by these birds slightly different in structure and filling the same place in nature, I must suspect they are only varieties. P200 Lecture 6
Type collections London ornithologist John Gould 1836 a series of ground finches, so peculiar in form an entirely new group containing 13 species P200 Lecture 7
Jeanne Sept 9/8/04 Natural theology Creationist Population Biology Geology Transmutation of species Seeing the gradation and diversity of structure in one, small intimately related group of birds, one might really fancy that, from an original paucity of birds on the archipelago, one species had become modified for different ends. Change through time Breeders select variable traits P200 Lecture 8
Cultural selection Natural selection Natural Selection differential reproductive success Variation & inheritance Individuals vary (genetically) Some inherited traits may help you survive (biological adaptations) Reproductive success = fitness Survival of the fittest - Competitive individuals are most likely to survive & reproduce Competition in environment Selection pressures - Value of traits to individual depends upon environmental circumstances 1859 monograph The Origins of Species by Means of Natural Selection Species vary and have changed through time Simple biological mechanism No special arguments for humans Alfred Russell Wallace P200 Lecture 9
Testing Darwin s Hypothesis Natural Selection in action ground finch % beak size large drought med small Selective Advantage Value of trait depends upon environment Selection pressures - environmental circumstances that favor particular adaptations P200 Lecture 10
Evolution = Descent with modification Natural Selection acts on individual Evolution occurs in populations Change in trait (gene) frequency through time Individuals don t evolve, populations do Micro-evolution Short-term process population level % shifts Macro-evolution Long-term process speciation Descendents of colonizer Genetic Family Tree Islands formed 500,000 years ago P200 Lecture 11
Origin of species P200 Lecture 12