Evolution

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Evolution

• Ideas That Shaped Darwins Thinking

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At the time

• Most people believed the Earth was only a few
  thousand years old
• Most believe species and the Earth has NEVER
  changed
• Most, but not all! New fossil evidence begins to
  shift many peoples veiwpoints

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Geology Perspective

• Hutton- proposed that Earth changes over time,
  including the rock cycle and other natural forces
  shape the earth proposed the Earth is millions
  of years old
• Lyell- proposed how volcanoes and other geologic
  forces can build and destroy landscapes

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Darwins Take

• Darwin thought if the Earth could change, why
  couldnt life change?
• Also, if the Earth is changing, plants and
  animals MUST change to survive!
• This begins his new theory of evolution.

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Economy/Ecology Perspective

• Malthus reasoned that if the human population
  continued to grow unchecked, food and shelter
  will run out (carrying capacity)
• This idea alone sprung forth the steps to natural
  selection.

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Other Evolution Hypotheses

• Lamarck stated that selective use or disuse of
  organs causes organisms to acquire or lose
  certain traits
• Then, these traits can be passed on to offspring
• ExCrab Claw
• Is this a valid hypothesis? Can you think of your
  own example?