15-1: The Puzzle of Life

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15-1 The Puzzle of Lifes Diversity

• Evolution change over time
• Theory well-supported, testable explanation of
  something that has occurred in the natural world.

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Charles Darwin

• Born February 12th, 1809.
• Joined the crew of the H.M.S. Beagle
  in 1831
• Collected samples from everywhere he visited.

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What Darwin Saw

• Many, many, many different species
• Different animals in similar environments
• Fossils very similar to living animals
• Fossils totally unlike living animals
• The Galapagos Islands
• Tortoises
• Finches

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15-2 Ideas That Shaped Darwins Thinking

• Life without evolution
• Nothing changed
• Fossils were of animals before some unidentified
  mass extinction event
• Darwin thought so, too, when he left.
• What changed his mind?

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Hutton and Lyell

• Hutton Explained that the Earths landscape
  has changed over time and that the Earth is very
  old.
• Lyell Principles of Geology Said that
  scientists must focus on what is observable.
• Geology is constantly changing.

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What that meant for Darwin

• If the Earth changes over time, might life change
  to adapt to it?

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Lamarck

• Lamarcks Hypotheses on Evolution
• Tendency Toward Perfection
• Use and Disuse
• Acquired Traits Passed On
• Lamarck was wrong, but he made people think
  about evolution.

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Malthus

• Said that if a human population got too large,
  then there would be increased competition for
  food and space.
• Darwin realized that this applied to all
  organisms.