1 INTRO TO EVOLUTIONARY THINKERS Adapted from a presentation originally designed by Mrs. Jennifer Boyd, WHS

2 Evolutionary Thinkers Readings Clarifying: 1. What part of the reading would you like to clarify? Find a specific section of the text that you would like to clarify. Content: 2. According to Lamarck, how does a species acquire new traits? Give an example to show your understanding. 3. In what ways does Darwin and Wallace’s proposal of how species acquire new traits differ from Lamarck’s? Scientific Argument: 4. In terms of the way the authors make their scientific arguments, whose argument is most convincing: Lamarck, Darwin, or Wallace? Use at least 2 specific passages from the text to support your conclusion.

3 I. Theories of Evolution A. Lamarck B. Darwin C. (Wallace)

4 A. Lamarck’s Explanation 1. Similar species come from a common ancestor. 2. Inheritance of Acquired Characteristics: a. Use and disuse b. Acquired traits are passed on to offspring. ◦ Acquired traits: traits not determined by genes. ◦ BUT….we now know…THEY CANNOT BE PASSED ON TO OFFSPRING. ◦ Ex. Birds with webbed feet. ◦ Ex. Giraffe’s long neck.

5 Make Your Own Lamarckian Argument! ◦ How would Lamarck explain the following scenario? In a particular rainforest, seeds of the eatumup fruit are found inside of a tough outer skin. Finch (a type of bird) with beaks that are shaped squarely and are strong enough can reach the seeds, a main source of food. A survey of the area shows there are fewer birds with rounded, weak beaks, and more birds with square, strong beaks.

6 B. Darwin’s Explanation ◦ Mid-1800’s ◦ Charles Darwin (1809–1882) and Alfred Wallace (1823–1913) independently proposed species were modified by natural selection.

7 1. Charles Darwin a. Career Path: ◦ Came from a wealthy English family. ◦ Dropped out of medical school. ◦ Decided to go to school to be a clergyman for the Church of England. ◦ Dropped that to become a Naturalist. ➢ Naturalist= a person who studies natural history, especially in zoology or botany. b. Travels: ◦ Sailed around the world on the H.M.S. Beagle for 5 years ◦ Darwin’s (unpaid) job on the ship was to collect specimens and record observations. ◦ Darwin observed different animals that had structures related to their eating habits.

8 1. Charles Darwin: Voyage of the Beagle

9 1. Charles Darwin: Darwin’s Data a. Darwin obsessively collected data. ◦ A bird specialist studied Darwin’s collection of Galápagos finches, and found 13 similar but separate species of finches. ◦ Each finch species has a distinctive bill that is specialized for a particular food source. What might this finding imply?

10 b. The similarities of the Galápagos finches implied that the finches shared a recent common ancestor c. They may have descended from a single species. 1. Charles Darwin: Darwin’s Data

11 2. Darwin’s Theories a. First theory: evolution, which is changes in a group of organisms over time, occurs. b. Second theory: natural selection causes evolution.

12 a. The newer forms appearing in the fossil record are modified descendants of older species. b. Darwin inferred that all species had descended from one or a few original types of life. 3. Descent with Modification

13 1. How is Lamarck’s explanation of the origin of different species different from Darwin’s explanation? 2. The similarities between the Galapagos finches suggested that they came from a __________ ancestor. 3. Why is the ability to reproduce important to natural selection? 4. Why was the Galapagos Islands a good place to study evolution? QUICK CHECK!

14 Glyptodont Armadillo c. So why don’t they look exactly like their ancestors? 3. Descent with Modification

15 ◦ Populations adapt to their environment as their proportion of genes for favorable traits increases. ◦ This results in changes in the genetic makeup of a population. ◦ Reproductive Fitness is KEY ◦ Organisms with favorable traits will be able to survive and reproduce = high reproductive fitness ◦ Favorable traits depend on the environment. 4. Modification by Natural Selection

16 Make Your Own Darwinian Argument! ◦ How would Darwin explain the following scenario? In a particular rainforest, seeds of the eatumup fruit are found inside of a tough outer skin. Finch (a type of bird) with beaks that are shaped squarely and are strong enough can reach the seeds, a main source of food. A survey of the area shows there are fewer birds with rounded, weak beaks, and more birds with square, strong beaks.

17 ll. Social Darwinism A. Application of Darwin’s idea of natural selection to human society 1. Very popular during the late 1800’s to mid 1900’s 2. Idea that people in the upper class had better genetics 3. Led to the idea of eugenics a. sterilizing people poor genetics or social standing to improve the human race b. Over 64,000 people were sterilized between 1907 and 1963 in the United States 4. Practices in the United States served as inspiration for Nazi Germany Social Darwinism at Work17

18 Learning Log: 1. Lamarck’s explanation of how species changed over time was flawed. Explain why. 2. Summarize Darwin’s explanation of how species change over time.