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History of Evolutionary Thought

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History of Evolutionary Thought ... (1809 1882) was born at Shrewsbury in northwestern England. He was sent to Edinburgh University at age 16 to study medicine. – PowerPoint PPT presentation

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Title: History of Evolutionary Thought


1
History of Evolutionary Thought
  • Diane Philip

2
I. What is Evolution?
  • Evolution a gradual process by which the living
    world has been developing following the origin of
    life.

3
II. 18th and 19th centuries
  1. Species were thought to have a fixed form.
  2. Species defined mostly by their morphology
    (appearance).
  3. World was believed to be perfectly designed and
    earth was very young.

4
II. 18th and 19th centuries
  • Classification system based on assumption that
    species were static (unchanging).
  • Carl Linnaeus (1708-1788) created hierarchical
    classification scheme with binomial naming (genus
    species).
  • Classification used as a method of organizing,
    not a way to show relationships.

5
III. Early Ideas of Evolution
  • George Louis Leclerc (1707-1778) French
    naturalist who first suggested evolution.
  • George Cuvier (1769-1832) Vertebrate zoologist
    who suggested Catastrophism (Mass extinction).
  • James Hutton (1726- 1797) Proposed the
    Uniformatarian Theory of geology.
  • Theory states that geologic processes happen at
    the same rate today that they have throughout the
    earths history.

6
III. Early Ideas of Evolution
  1. Jean Baptiste Lamarck (1744-1829) French
    naturalist and taxonomist. He proposed the Theory
    of Acquired Characteristics.

7
IV. Enter Darwin (1809-1882)
  • Early Life
  • Charles Darwin (18091882) was born at Shrewsbury
    in northwestern England.
  • He was sent to Edinburgh University at age 16 to
    study medicine.
  • In 1827 he was sent to Cambridge University to
    become an Anglican clergyman.

8
IV. Enter Darwin (1809-1882)
  • Voyage of the H.M.S Beagle
  • Asked by Capt. Robert FitzRoy on a voyage to
    chart South America coast in 1831.
  • Read Principles of Geology by Charles Lyell,
    which discussed theory of uniformitarianism.
    Wanted to extend it to all animals.
  • Noticed family resemblance between species
    (living and fossil) in areas he studied.

9
IV. Enter Darwin (1809-1882)
  • Galapagos Observations
  • different islands, climates, vegetation
  • differences in animals (tortoise finch)
  • could these differences be the result of the
    differences among islands?
  • could each animal have come from a common
    ancestor?

10
IV. Enter Darwin (1809-1882)
  • Development of Natural Selection
  • Malthus said as the human population outgrows
    its resources, members must compete for what is
    available.
  • Darwin thought the same principle might apply in
    nature.
  • Individuals with favorable traits might have an
    advantage in survival and reproduction.
  • Favored individuals would pass their traits on to
    their offspring.

11
IV. Enter Darwin (1809-1882)
  • Darwin and Alfred Russel Wallaces papers were
    presented as a scientific meeting in 1858 but
    received little fan fare.
  • Darwins findings were published in a book On
    the Origin of Species in 1859.

12
V. Neo-Darwinian Synthesis
  • After about 1870, scientific evidence piled up
    against natural selection
  • The Earth was too young.
  • Apparent swamping of favorable variations.
  • Lack of transitional forms in the fossil record.
  • Biologists convinced that evolution had occurred
    but no longer saw natural selection as its chief
    mechanism
  • The main scientific objections to Darwinian
    natural selection theory were answered by the
    1930s
  • Discovery of radioactivity and later studies of
    decay rates showed age of earth to be 4 billion
    years.
  • Swamping inheritance problem and lack of
    transitional forms in fossil record both resolved
    by Mendelian genetics.
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