Charles Darwin

1. Charles Darwin “. . .a theory of descent with modification through variation and natural selection.”

2. The Expansion of Science • Descartes' “Mechanical world” made science possible • Carl von Linné (Linnaeus) published Philosophia Botanica (1752) • William Paley published Natural Theology (1802) • The Age of Reason promoted the idea of “Progress” in science--more can be discovered.

3. “Whoa! What is this? Scientific Research Posed Problems Question # 1 How do we account for fossils of species that appear to be extinct? In the Great Chain of Being, every species had a vital role to play in God’s vast ecological network. God would not make spare parts.

4. Where are these species hiding? Scientific Research Posed Problems Question # 1 John Wesley, the famous religious reformer, pronounced, in 1770,“Death is never permitted to destroy [even] the most inconsiderable species.”

5. Scientific Research Posed Problems Question # 2 The fossils of some extinct species, e.g., mammoths, giant sloths, horse-like creatures, seemed to resemble contemporary species. Were they related; if so how?

6. Archaeopteryx and bird details Homo Erectus Homo Sapiens The Fossil Record—Apparent Links

7. The Fossil Record—Is this a Link?

8. Scientific Research Posed Problems Question # 3 How do we account for the geographic distribution of animals in the world, e.g., marsupials and flightless birds in Australia, finches and turtles in the Galapagos Asian and African elephants? Did that all occur at the end of the trip on the biblical ark? How did they spread in such exact patterns?

9. Scientific Research Posed Problems Question # 4 Why does there appear to be a progression of complexity of fossils found in different layers of the earth’s crust, with no species or simple species in the oldest layers, and vertebrates appearing in more recent layers only?

10. Scientific Research Posed Problems Question #5 How do we account for the many evidences that the earth is millions of years old?

11. Scientific Research Posed Problems Question # 6 How do we reconcile the evidence that people and animals have been dying steadily for thousands or billions of years with the biblical idea that Adam’s fall first brought death into the world?

12. How do we reconcile these strange new observations with biblical creation,the story of the fall, and the story of the flood?

13. Early Answers

14. Cuvier’s Proposal The world has gone through a number of great catastrophes, with the flood being the last. After each catastrophe, God would repopulate the earth with a new creation and a batch of new species.

15. A New Proposal Charles Darwin, in 1859, proposed a “theory of descent with modification through variation and natural selection.”

16. Charles Darwin--Background It was intended that Charles, like his father and grandfather, would become a doctor. At Edinburgh, he could not bear to watch the surgeries, done without anesthesia, so he dropped out. Later, he finished his studies at Cambridge, where he studied for the ministry. However, at Cambridge he developed a passion for collecting biological specimens.

17. Charles Darwin--The Journey His mentor at Cambridge, Henslow, recommended him to be ship’s naturalist on the HMS Beagle. Darwin embarked on Dec. 27, 1831, for what became a 5-year trip mapping the coastlines around South America and elsewhere. He took with him volume 1 of Sir Charles Lyell’s new book, Principles of Geology. This book argued that the world was millions of years old, with changes taking place slowly.

18. Charles Darwin--After the Journey Darwin’s journals and specimens had assured him a good reputation before he had returned. He “wrote the book” on the formation of coral reefs. He did ground-breaking research on barnacles.

19. Charles Darwin--The Theory Darwin, in 1838, read Robert Malthus’s Essay on Population, that argued that animals would have to struggle to survive since they would multiply faster than the food supply. For the first time, Darwin thought of a mechanism to explain how extinct species could be related to current species and how species could vary.

20. Charles Darwin--The Theory In 1842, he wrote out a 35 page pencil sketch of his ideas. In 1844, he expanded it to 231 pages, put the manuscript in a safe with some money and instructions to publish it after he was dead. He wrote to Lyle, Hooker, Huxley and others, explaining his theory. He continued research on the theory of natural selection.

21. Charles Darwin--The Theory In 1845, he wrote, “In my wildest daydream, I never expect more than to show that there are two sides to the question of the immutability of species.” (Irvine) During the next few years, he corresponded with Alfred Russell Wallace, a naturalist in Indonesia whose observations were leading him in the direction Darwin had gone. But Wallace’s ideas were tentative and undeveloped.

22. Charles Darwin--The Theory The bombshell came on June 18, 1858. Wallace sent a long letter, reaching the same conclusions in an uncanny parallel to the way that Darwin had. Hooker and Lyle presented Wallace’s and Darwin’s papers to the Royal Society. Darwin was ill and home grieving over the death of an infant daughter to Scarlet Fever..

23. Charles Darwin--The Theory In 1859, Darwin published Origin of Species, one of the most important books of the 19th century. It proposed “. . .a theory of descent with modification through variation and natural selection.”

24. Darwin’s Three Premises • Creatures produce more offspring than can survive. • There is great variation within a species. • Some of that variation is passed on to future generations.

25. Darwin’s First Premise • Creatures produce more offspring than can survive. From Robert Malthus, Darwin got the idea that the population of a species grows faster than the food supply; therefore, there will be a competitive struggle for food. In the process of the struggle for food, those more fit will live.

26. Owl? Who, him? Darwin’s Second Premise There is great variation within a species. From his travels on the Beagle, on which he collected thousands of specimens, as well as in his observations of pigeons, dogs, other domesticated animals, and the human species, Darwin observed a huge variety within a species. Even within this class, we all vary.

27. Darwin’s Third Premise Some of that variation is passed on to future generations. Although Darwin had not read Mendel, he knew, as we do, that some of the variation that randomly occurs within a species is passed on. For example, people born with an extra finger (polydactyly) often had descendants with extra digits. Sheep with thicker wool were bred (artificially selected) to produce offspring with thicker wool. Cows giving more milk are bred to produce offspring who also give more milk.

28. Darwin’s Conclusion--# 1Natural Selection • In a natural setting, through natural selection, the variation that helps an organism adapt to the environment, i.e., get food, escape predators, and find a mate, is most likely to be passed on.

29. Darwin’s Conclusion--# 2Varieties could become new Species • Given the geologic age of the earth outlined by Lyle, the variation occurring within a species could become so great that varieties would become new species. • Given enough time, all species could have evolved from one prototype.

30. Evolution -- Fact or Theory? • Since “descent with modification,” or evolution, is a fact, what is the big controversy over Darwin’s theory? • Dogs, which come from one common ancestor, have evolved into great varieties. • Cows give more milk, pigs have less fat, tomatoes are larger, sheep have more wool, turkeys have more white meat--many things have evolved.

31. Darwin’s Controversy # 1Natural Selection The controversy hinges on two main points. First, while the variety among dogs, cows, etc., is created by artificial selection, Darwin argued that competition in nature would cause the same kind of variety by natural selection, unguided by a divine providence.(This is a natural offshoot of Cartesian Mechanism, in which the material world acted according to natural laws.)

32. Darwin’s Controversy # 2New species could evolve from varieties Second, given the huge expanse of time which had been proposed by contemporary geologists, Darwin proposed variations within a species could cross the genetic line and become separate species. In fact, concludes Darwin, all species might be developed from one original prototype, again, possibly without divine intervention.

33. Summary • Darwin did not introduce the idea of evolution; rather, he proposed the theory of Natural Selection. • Darwin did not claim that humans came from apes; rather, he theorized that all species may have come from earlier prototypes, perhaps from one single prototype. • His theory has profoundly affected the way we think about science and nature. • For over a century, his basic claims have been largely supported by scientific studies.

34. Herbert SpencerThe Application of Evolutionary Thought to Society in “Social Darwinism” • Spencer was a prominent Victorian scientist whose aim was to bring fields such as psychology and sociology within the same framework and rigor as the natural and biological sciences. • His social theories became known as “Social Darwinism” and were applied to capitalism, communism, and the nationalism that was the beginnings of the Nazi movement.

35. Herbert SpencerThe Application of Evolutionary Thought to Society • Capitalism and “Social Darwinism” Capitalists such as Andrew Carnegie and John D. Rockefeller argued that capitalism was the best form of “survival of the fittest.” They argued that the government should not help the poor, infirm, or unfit. If the lower classes died in their factories of mills, that was just a natural process by which society was improved. Rockefeller called it “a Law of God and of Nature.”

36. Herbert SpencerThe Application of Evolutionary Thought to Society • Communism and “Social Darwinism” Karl Marx saw in “Social Darwinism” the idea that we could alter the environment of individuals and thereby develop new traits and qualities. For example, the abolition of private property could lead to humans getting rid of their aggressions, leading to a Utopian society.

37. Herbert SpencerThe Application of Evolutionary Thought to Society • Nazism and “Social Darwinism” Early German nationalists argued that nations were essentially the same as members of a species. When fighting between nations occurred, the human race was made “fitter.’ They also argued that it was a natural process to eliminate inferior nations or peoples.