Darwin’s Theory of Evolution

1. Darwin’s Theory of Evolution

2. Theories of Life • Divine creation- supreme being or beings created all life • Extraterrestrial origin- life did not originate on this planet but elsewhere • Evolution- process by which modern organisms have descended from ancient organisms

4. Who was Charles Darwin? • Originally a student of theology • Then became a naturalist • In 1831, took ship and sailed around the world • During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time

5. Darwin’s Voyage

6. Darwin’s Observations • Patterns of diversity • HUGE amount of diversity among living things • Diversity in • Traits • Offspring production • Habitat

7. PROCESS BOX • Based on what you know about various organisms, give your own examples of variation you have seen in offspring. Please give one for each category listed above • 3 line minimum

10. The Galapagos Islands • Located west of South America • Islands were close but had very different climates • Very fascinated by both the tortoises and the finches on these islands • Tremendous variety

13. The ride back home • Darwin’s return provided a lot of time for reflective thought • Darwin observed that the characteristics of many animals and plants varied noticeably among the different islands of the Galápagos. • Critical point

14. The ride back home • Darwin came up with a possibility • Could the animals on the different islands have once been the same species? • Was that even possible??

15. Ideas that shaped Darwin’s Ideas • Darwin built upon the work of those before him • Other scientists built upon his work • But… • Many people were shocked by his ideas and he did not receive a lot of initial support

17. Evolutionary Roadblocks • Ideas in Darwin’s time • Earth was only a few thousand years old • Later shown to be billions of years old

18. Evolutionary Roadblocks • Ideas in Darwin’s time • Both the planet and its organisms were immutable (could not change) • Planet is always changing…and the life on it

19. Evolutionary Roadblocks • Ideas in Darwin’s time • Any strange geologic features were the results of infrequent catastrophes that humans rarely witnessed • Simply not true

20. Roadblocks Roadblock #1 Roadblock #2 Roadblock #3

21. People who influenced Darwin • Scientists had a large influence on Darwin 1. James Hutton 2. Charles Lyell 3. Jean Baptiste Lamarck • …And an economist 4. Thomas Malthus

22. Layers of rock are built very slowly Geological forces shaped Earth’s features (mountains and valleys) Took MILLIONS of years Earth is not a few thousand years old 1. James Hutton

23. Wrote Principles of Geology Stressed that processes that shaped Earth millions of years ago are the same processes that do so today 2. Charles Lyell

24. PROCESS BOX • In what ways were the influences of Lyell and Hutton similar?In what ways were the influences of Lyell and Hutton different? • 3 line minimum

25. Did realize that organisms change over time Published his work the year Darwin was born (1809) 3. Jean-Baptiste Lamarck

26. Lamarck’s Proposition • Lamarck proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species. • Had three supporting principles

29. A. Tendency Towards Perfection • All organisms have a tendency towards perfection and complexity • Acquired features that helped them live more successfully in their environments • EX: Giraffe has an urge to be tall, and tries to do so

30. B. Use and Disuse • Organisms could alter the size and shape of their organs by using them in new ways • If an organ was not used, it would eventually disappear • EX: By trying to be tall, giraffe stretches its neck out

31. C. Inheritance of Acquired Traits • If an organism altered its body structure during its lifetime, then it would pass the new trait to its offspring • EX: If the giraffe stretched its neck and it got longer, its babies would have longer necks

33. PROCESS BOX • Pick an organism different than the giraffe. Use Lamarck’s three principles to describe the organism could have changed over time.USE COMPLETE SENTENCES! • 5 line minimum

34. 4. Thomas Malthus • Looked at population • Notice that babies were being born faster than people died • Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

35. 4. Thomas Malthus • Looked at population • Thought that war, famine, and disease were the only things that keep the population in check • Darwin realized this was true for every organism, and not just humans • Most offspring die • WHY do some die and some survive?

36. PROCESS BOX • Pick an organism different than the giraffe. Use Lamarck’s three principles to describe the organism could have changed over time.USE COMPLETE SENTENCES! • 5 line minimum

37. 4. Thomas Malthus • Food supply is linear • Population growth is exponential

38. Evidence supporting Darwin’s Ideas • Fossil Evidence • Homologous Structures • Analogous Structures • Vestigial Structures • Comparative Embryology • Biochemical evidence

39. 1. Fossil Evidence • Fossil evidence shows that living things have been changing on earth for millions of years. • Also showed that the geographic distribution of organisms lines up with the movement of the earth’s crusts & that newer (more modern) forms of fossilized organisms are found in the upper layers of rock

41. 2. Homologous Structures • Structures that have similar form but different functions • Bones of our forearm, the front flipper of a whale, the wing of a bat & legs of a turtle. • Could all four limbed animals with backbones have descended with modification from a common ancestor?

44. 3. Analogous Structures • Structures that have same function but different structure/structure • Fly and Bird wing • Was environment similar so it made sense to have this feature?

46. PROCESS BOX • How do homologous and analogous structures compare to each other? • 2 line minimum

47. 4. Vestigial Structures • Structures which no longer have a function to the organism. • Our appendix, hair, coccyx, wisdom teeth • These vestiges had a useful function at one time but since they are no longer of an adaptive use to the organisms, they have become reduced with time.

50. 5. Comparative Embryology • Compares structures of developing organisms (embryos) • Structures found in embryos that have no function/use or are not present in adults • Early stages of development of many animals with backbones are very similar • Common ancestor!