1. Bell Work 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.

2. Bell Work 1. 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 Lyell and Hutton, Lamarck, and Malthus

4. Ideas that shaped Darwin’s Thinking Darwin’s voyage came at a critical time in the history of science → explores were traveling the world and great thinkers were beginning to challenge established views about the natural world  These ideas influenced Darwin’s thinking, and in turn, Darwin’s ideas influenced others

5. Common Beliefs of the Time 1) Most Europeans believed the Earth and all its life forms were created a few thousand years ago 2) Neither the planet nor its living species changed over time Many discoveries changed these views, including the expanding fossil record

6. An Ancient, Changing World Scientists studying the Earth began uncovering evidence that suggested that the planet was very old and had changed slowly over time * Hutton and Lyell helped scientists recognize that the Earth is many millions of years old and the processes that changed Earth in the past are the same processes that operate in the present

7. Processes that Shape the Earth Rock layers are moved up or pushed down (Plate Tectonics) The Earth’s surface is shaped by a variety of natural forces including rain, wind, changing temperatures, etc. (erosion)

8. Processes that Shape the Earth Sea level Sedimentary rocks form in horizontal layers. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers. As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. New sediment is then deposited above the exposed older rock surface. Sea level

9. Influence on Darwin These ideas helped Darwin appreciate the significance of geologic phenomena that he had observed; this understanding influenced Darwin in two ways: 1. Darwin asked himself: If the Earth can change over time, might life change as well? 2. Darwin realized that it would take many years for life to change as he suggested.

10. Lamarck’s Evolution Hypothesis Lamarck was among the first scientists to recognized that living things changed over time – and that all species descended from other species  Lamarck also realized that organisms were somehow adapted to their environment

11. Lamarck’s Idea About Evolution Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits over their lifetime. These traits could then be passed on to their offspring. Over time this process led to change in a species.

12. Lamarck’s Idea About Evolution Lamarck believed: 1. Organisms have a natural tendency toward perfection 2. Organs can be altered through use or disuse 3. Acquired traits are inherited * Lamarck’s hypotheses are incorrect in several ways, but he was right in that he recognized that organisms were adapted to their environment.

13. Lamarck’s Idea About Evolution

14. Population Growth Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone  Malthus observed that war, famine, and disease worked against this population growth

15. Influence on Darwin Darwin recognized that this reasoning applied directly to plants and animals, which generally produce far more offspring than humans Examples: A maple tree produces thousands of seeds in a single summer; an oyster can produce millions of eggs each year * Why isn’t the Earth covered with Maple trees and oysters?

16. Main Ideas 1) The Earth is very old (~4.5 billion years old); the planet and its living organisms change over time 2) Organisms are adapted to their environment 3) Organisms produce many more offspring than survive to reproduce