1. Chapter 15 Darwin’s Theory of Evolution
15-2 Ideas That Shaped Darwin’s Thinking

2. My, How You’ve Changed!
Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about
Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.
2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument.
3. Which of the items in your lists do you think you might pass on to your children? Explain your answer.

3. Ideas That Shaped Darwin’s Thinking
A. An Ancient, Changing Earth
Hutton & Lyell helped scientists recognize that Earth is many millions of years old
The processes that changed Earth in the past are the same processes that operate in the present

4. Ideas That Shaped Darwin’s Thinking
3. Hutton’s Theory of Geological Change
Hutton proposed that rocks, mountains & valleys are shaped by geological processes (rain and temperature) that happen over millions of years
Thus, the Earth must be more than a few thousand years old

5. Ideas That Shaped Darwin’s Thinking
4. Lyell’s Principles of Geology
Geological features, will change over time and past events must be explained from processes that can be observed
Darwin realized that it must have taken many years for living things to change this way and so the Earth must be extremely old