History of Natural Theology

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History of Natural Theology

• Classical Greek philosophers had ideas about the
  natural evolution of life
• Plato (427-347 B.C.) believed there were two
  worlds. A real world which was perfect and an
  illusionary world that was imperfect.
• He did not believe in evolution.
• His student Aristotle (384 -322 B.C.) believed
  that all forms could be arranged on a ladder or
  scale called the scala naturae Each form of
  life had an allotted rung on the ladder.
• Belief prevailed for 200 years.

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Carolus Linnaeus(1707- 1778)

• Father of taxonomy.
• Taxonomy is the branch of biology concerned with
  naming and classifying organisms.
• Came up with Kingdom, Phylum, Class, Order,
  Genus, Species.
• However he believed there was no evolutionary
  kinship between them.

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Georges Cuvier(1769-1832)

• Paleontologist.
• Documented and recorded the succession of fossils
  in sedimentary strata in the Paris Basin.
• Found deeper and older fossils to be dissimilar.
  New species appear and older species disappear.
• Advocated catastrophism. Species killed off by
  catastrophes and recreated.

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James Hutton(1726-1797)

• Scottish geologist.
• Proposed gradualism .
• Profound changes are due to gradual changes over
  a long period of time due to natural processes
  occurring within the Earths crust.

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Charles Lyell (1997-1875)

• Proposed uniformitarianism. The idea that
  geological processes have not changed over time
  and are at work.
• Suggested the earth was a lot older than the
  previously thought 6000 years.
• Processes persisting over long periods of time
  can accumulate to substantial change.

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Charles Lyell
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Jean Baptist Lamark

• Was in charge of an invertebrate collection at
  the Natural History Museum in Paris.
• Noticed that species changed over time.
• Proposed that phenotype can change in response to
  environment changes and those new characteristics
  were passed on to the offspring.
• First idea that adaptations occur in response to
  the environment.

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Jean Batist Lamark
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The Darwinian Revolution

• Charles Darwin(1809 -1882) was born in Shrewsbury
  England.
• Wanted to be naturalist but was sent to medical
  school in Edinborough at 16.
• He dropped out and went to Christ College at
  Cambridge University and became a clergyman.
  Back then most naturalist were clergyman.
• Viewed the world as natural theologists.
• The view that each species was newly designed
  and non-evolving.

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Darwin 1875
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Reverend Robert Henslow

• Botany professor at Cambridge.
• Darwin was his protégé
• At age 22 he was recommended to join Captain
  Robert Fitzroy on the H.M.S. Beagle to sail
  around the world.
• The primary mission was to chart the South
  American coastline.
• Darwin collected and observed the flora and
  fauna.

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H.M.S. Beagle Voyage
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Descent With Modification

• A Darwinian View of Life

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The Galapagos

• Species unique although they most closely
  resembled South American species.
• Darwins finches possessed different beaks to
  accommodate different modes of eating.
• Darwin read Principles of Geology by Lyell and
  surmised that old Earth was inhabited by
  evolving species.

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Darwins Finches
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The Origin of Species

• Lyell and a collegue presented Darwins work
  Along with another Bristish scientist by the name
  of Alfred Wallace.
• The paper was on the theory of Natural
  Selection which Wallace and Darwin came up with
  simultaneously.
• Darwin published The Origin of Species a year
  later.

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Alfred Wallace
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Darwins Observations

• Species had distinct South American
  characteristics.
• South American species that lived in the
  temperate regions more closely resembled the
  tropical species on the same continent than
  species that resided in the temperate regions on
  a different continent.
• South American fossils resembled south American
  species.

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Observations That Lead Darwin to the Theory of
Natural Selection

• OBSERVATIONS
• All species have the potential to reproduce the
  maximum number of offspring.
• Populations remain a stable (except for seasonal
  fulgurations.
• Resources are limited
• CONCLUSION
• Organisms compete for food.

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Other Observations

• Organisms vary
• Organism with suitable traits survive to
  reproduce.
• Gradual changes in a population occur and the
  population accumulates favorable characteristics.

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Additional Evidence for Natural Selection

• Homology similarities in characteristics due to a
  common ancestor.
• Anatomical homologies
• similar structures, different function.
• Embryological homologies
• Similar structural development.
• Molecular homologies
• Basic machinery of RNA and DNA are similar.
• Biogiographic homologies
• Convergent evolution

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Homologies

• Biogeographic homologies
• Endemic species.
• Convergent evolution - species that look similar
  but have no common ancestry.
• Divergent evolution species that have common
  ancestry but evolve disparate characteristics.
• Fossil Record the appearance of certain classes
  of vertebrates in the fossil record.
• Fish before amphibians

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Homologous Structures
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Convergent Evolution
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Natural Selection

• Differential success in reproduction.
• Variation in populations and how they respond to
  the environment.
• The product of adaptation to their environment.

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Descent With Modification
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Cartoon of Darwin