1. Ideas That Shaped Darwin’s Thinking
Evolution
Ideas That Shaped Darwin’s Thinking

2. 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 people’s veiwpoints

3. 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

4. Darwin’s Take…
Darwin thought if the Earth could change, why couldn’t life change?
Also, if the Earth is changing, plants and animals MUST change to survive!
This begins his new theory of evolution.

5. 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.

6. 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
Ex:Crab Claw
Is this a valid hypothesis? Can you think of your own example?