history of evolutionary thought


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history of evolutionary thought

  1. 1. EVOLUTIONBiology 1 / SY 2006-2007
  2. 2. Evolution Definition - gradual change over time - L. e-, out + volvere, to roll Types GEOLOGIC EVOLUTION BIOLOGICAL or ORGANIC EVOLUTION The foundation of modern evolutionary thought was described by Charles Darwin
  3. 3. THE ROAD TO EVOLUTIONARY THEORY Evolution Before DarwinGreek Philosophers• Plato’s Idealism• Aristotle’s scala naturae (scale of nature) special creation of each species organisms were created in their current form the earth was only a few thousand years old
  4. 4. THE ROAD TO EVOLUTIONARY THEORY Evolution Before DarwinCARL Von LINNE• Swedish botanist• worked on the classification of plants• published Species Plantarum (~7,300 plants)• ordered classification of plants based on their similarities  showed the natural relationships of plants
  5. 5. THE ROAD TO EVOLUTIONARY THEORY Evolution Before DarwinTHOMAS MALTHUS• economist & clergyman• published An Essay on the Principle of Population Populations had an inherent tendency to increase geometrically,while the resources needed to support this growth increase slowly ornot at all. Because of the continued growth of a species would outstripneeded resources, growth would be limited.
  6. 6. THE ROAD TO EVOLUTIONARY THEORY Evolution Before Darwin JEAN-BAPTISTE de LAMARCK • French biologist • proposed that modern species descended from other species • Lamarckism based on two theories:1. Inheritance of Acquired Characteristics - traits acquired by an individual during its life are passed to its offspring2. Use and Disuse - organs of the body that were used extensively to cope with the environment became larger and stronger, while organs that were not used deteriorated
  7. 7. THE ROAD TO EVOLUTIONARY THEORY Evolution Before DarwinExample:The Evolution of the GiraffeGiraffes obtained their long necks fromprevious giraffes who stretched to eat theleaves of high tree branches.Stretching increased the length of theirnecks, and this acquired characteristicwas passed to the next generation.
  8. 8. THE ROAD TO EVOLUTIONARY THEORY Evolution Before DarwinLamarckism• first to present a unified theory that attempted to explain the changes in organisms from one generation to the next• although mechanisms proposed for change was wrong, since acquired characteristics are not heritable!!!  origin of species from preexisting species  ability of organisms to adapt
  9. 9. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)GEORGES CUVIER• French anatomist and naturalist and writer• paleontologist• strongly opposed the concept of evolution history of living organisms recorded in layers of rock containing a succession of fossil species in chronological order fossils were organisms that had died in a series of catastrophes, after which extinct plants and animals were replaced by the immigration of distant species to the devastated region  Catastrophism
  10. 10. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)JAMES HUTTON• Scottish geologist• took up law, medicine and agriculture• published Theory of the Earth geological change occurred slowly but continuously by the process of Gradualism sedimentary rock that encased fossils formed by the gradual accumulation of sediments in bodies of water
  11. 11. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)CHARLES LYELL• Scottish lawyer turned geologist• published Principles of Geology Uniformitarianism - the processes that alter the Earth are uniform through time believed Hutton’s evidence for gradualism indicated that the earth was millions of years old believed that even the slow and subtle processes could cause substantial change over time
  12. 12. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)GEORGES CUVIERJAMES HUTTONCHARLES LYELLGeological evolution  the earth is very old and constantly changing  life existed millions of years ago• geologists were convinced of an ancient earth, but were at odds over how to explain the appearance and disappearance of species in the fossil record• believed in in special creation
  13. 13. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)GREGOR MENDEL• Austrian biologist• discovered the basic principles of heredity• father of Classical Genetics Individual characteristics determined by inherited factors transmitted from parent to offspring.
  14. 14. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)CHARLES DARWIN• voyage on the H.M.S. Beagle (1836)• published (1859) The Origin of Species• first person who proposed a mechanistic approach to evolutionary thought• the father of synthetic evolution
  15. 15. The Voyage of the Beagle
  16. 16. On the GalapagosIslands... Galapagos tortoise Darwin’s finches Most organisms on the islandswere endemic.
  17. 17.  species not specially created in their present forms, but had evolved from ancestral species proposed a mechanism for evolution: Natural Selection A population of organisms can change over time as a result of individuals with certain heritable characteristics leaving more offspring than other individuals.
  18. 18. THE ROAD TO EVOLUTIONARY THEORY Darwin’s Time (1800s)ALFRED RUSSELL WALLACE• English naturalist• studied the Malay archipelago and Amazon• proposed a theory of evolution similar to Darwin’s “Then I saw at once that the ever-present variability of all living things would furnish the material from which, by the mere weeding out of those less adapted to the actual conditions, the fittest alone would continue the race.”
  19. 19. Darwinism in Historical Context
  20. 20. THE ROAD TO EVOLUTIONARY THEORY Neo-Darwinian/Contemporary Times HUGO CARL ERICH VON DE VRIES CORRENS TSCHERMAK• rediscovered Mendel’s laws of heredity• the start of rediscovering evolution in terms of Mendel’s ideas
  21. 21. THE ROAD TO EVOLUTIONARY THEORY Neo-Darwinian/Contemporary TimesJAMES WATSONFRANCIS CRICK• elucidated the structure of DNA (genetic material)• DNA contains coded information which acts as a blueprint for the transfer of hereditary information from generation to generation• mutation as the raw material for evolution