What is Evolution

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What is Evolution?

• Change over time
• Darwin called it Descent with modification

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Evolution Timeline
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Pre-Darwinian Thought

• Essentialism
• Greek philosopher Plato (427-347 B.C.)
• Individuals are all imperfect attempts at an
  essential (ideal) form
• Believed to explain why variation exists among
  individuals but also emphasizes that species are
  fixed or unchanging over time

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Pre-Darwinian Thought

• 17th century, Creationism was main religious
  view strongly influenced by biblical studies of
  James Ussher (1581-1656)
• Earth thought to be 6,000 yrs old (based on
  bible)
• Species were created and do not change (literal
  meaning of creationism)

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Pre-Darwinian Thought

• Carolus Linnaeus (1707-1788), Swedish scientist
  who invented scientific naming (taxonomy) and
  hierarchical classification system
• Described many species but believed in
  creationism no attempt to explain why
  differences existed

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Hierarchical Classification System-Leopard
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Hierarchical classification system-Honey Bee

• Domain-Eukarya
• Kingdom-Animals
• Phylum-Arthropods
• Class-Insects
• Order-Hymenoptera
• Family-Bees
• Genus-Apis
• Species-Apis mellifera

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Pre-Darwinian Thought

• Comte de Buffon (1707-1788)
• Rejected age of earth as 6,000 yrs old
• Proposed that species could change and show
  relationships to each other
• Pressured by church to recant

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Pre-Darwinian Thought

• Geologists Hutton (1726-1797) and Lyell
  (1797-1875) developed uniformitarianism, idea
  that earth evolves slowly due to erosion,
  volcanism, and sedimentation
• Earth must be older than 6,000 yrs old

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Pre-Darwinian Thought

• Geologist Cuvier (1769-1832) proposed
  Catastrophism to counter arguments of Hutton
  and Lyell that earth must be older than 6,000 yrs
  old
• Cuvier proposed that fossils are from a series of
  older floods, flood of Noah (Genesis flood) was
  most recent
• Problems-many more layers of fossils than floods
  mentioned in bible

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Pre-Darwinian Thought

• Jean Lamarck (1744-1829) proposed that species
  evolve over time
• However, the mechanism that he proposed,
  Inheritance of acquired characteristics was
  incorrect

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Charles Darwin

• Charles Darwin (1809-1882)
• Wrote Origin of Species (by means of natural
  selection), 1859
• Proposed that species evolve through mechanism he
  called
• Natural selection

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Darwins trip on the HMS BEAGLE

• Darwin traveled the world

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Darwins trip on the HMS BEAGLE

• Galapagos islands
• Saw unique groups
• of plants and animals
• due to islands isolation
• from S. America

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Darwins trip on the HMS BEAGLE

• Galapagos Finches were studied that had different
  types of beaks

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Adaptive Radiation

• Proposed to explain origin of many closely
  related species (like Darwins finches) from one
  common ancestor

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Influences on Darwin

• Writings of Thomas Malthus (1766-1844)
• Essay on Population
• Food supply will not grow as fast as population
  increase, lead to famine and competition

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Influences on Darwin

• Alfred Wallace (1823-1913)
• Simultaneously proposed evolution through natural
  selection
• Co-presented their theories to the Royal Society
  in London, Darwin was first to publish his book