VIEWS: 3 PAGES: 39 POSTED ON: 11/22/2012
Charles Darwin “. . .a theory of descent with modification through variation and natural selection.” The Expansion of Science • Descartes' “Mechanical world” made science possible (although Descartes himself was not an empiricist) • Carl von Linné (Linnaeus) published Philosophia Botanica (1752) • The Age of Reason promoted the idea of “Progress” in science--more can be discovered. The Industrial Revolution begins. 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. “Whoa! What is this? Scientific Research Problems Question # 1 John Wesley, “Such is the the religious economy of reformer, nature, that no pronounced, instance can be in 1770, produced of her “Death is never having permitted to permitted any destroy [even] one race of the most Where are these animals to inconsiderable species species.” hiding? become extinct.” Thomas Jefferson, 1785 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? The Fossil Record—Apparent Links Archaeopteryx and bird details Homo Erectus Homo Sapiens The Fossil Record—Is this a Link? 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 the species spread in such exact patterns? Why are more closely related species usually found closer to each other (e.g., hummingbirds in the Galapagos, drosophila in the Hawaiian islands). 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? Why are there no species or only simple species in the oldest layers, and why do vertebrates appear only in more recent layers? Why are species in closer layers more closely related? Scientific Research Posed Problems Question #5 How do we account for the many evidences that the earth is many millions of years old? Scientific Research Posed Problems Question # 6 How do we reconcile the evidence that people have been living and dying for thousands of years with the Bible record? How do we reconcile evidence that animals have been living and dying steadily for millions of years with the biblical idea that death did not occur until after Adam’s fall. How do we reconcile these strange new observations with biblical creation,the story of the fall, and the story of the flood? Early Answers De Maillet—1748 Aquatic animals evolved land counterparts De Maupertuis—1745 Species are not fixed. Acquired traits or sports may be passed on Buffon—1749,1766 Families were fixed, but variation of species in families could vary Lamarck—1802,1809 Species evolved by passing on acquired characteristics Erasmus Darwin—1731- Supported evolutionary 1803 ideas similar to Lamarck Ralph Waldo Emerson on Evolution [Ralph Waldo] Emerson's fledgling evolutionary faith began to emerge in his 1834 lecture "The Relation of Man to the Globe.“ [after reading Sir Charles Lyell’s Principles of Geology] . . . "Man," Emerson said, "is no upstart in the creation, but has been prophesied in nature for a thousand thousand ages before he appeared." . . . “[F]rom times incalculably remote" there had been a "progressive preparation" for the human species, carried out in the lower or "meaner creatures" preceding it. "Man," as Emerson told his audience, "was not made sooner, because his house was not ready."4 Emerson (Cont’d) In this same lecture, Emerson chronicled the way in which the hard rock that once surfaced the earth gradually became covered with soils more hospitable to life. With this development the "first faint traces of vegetable and animal life begin to appear, and in the lowest strata the most imperfect forms; – zoophytes, shells, and crustaceous animals; then fishes and reptiles."5 When these rudimentary forms had existed for some time, "Then a new formation – the remains of a new and higher order – begin to appear, more nearly resembling man, and giving earnest of his approach; and as the new race waxes, the old race retires."6 Emerson (Cont’d) As a result of his scientific studies, Emerson concluded that one of the distinguishing characteristics of the "present age" was "the study of organic remains," and that "solid learning is got from the fossils." When we look at the geologic record, he reflected, there are "No leaps, no magic," but rather the "eternal tranquil procession of old familiar laws.” (Gordon, Robert C., PhD) 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. A New Proposal Charles Darwin, in 1859, proposed a “theory of descent with modification through variation and natural selection.” 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. 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. 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. Charles Darwin--The Theory Darwin, in 1838, read Robert Malthus’s Essay on Population, an essay 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. Nature was not unlike a breeder of horses; creatures with mutations that helped them get a meal (or escape being a meal) and a date were selected over others. Natural Selection at work <Bird of Paradise> 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. 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. Darwin--The Impetus to Publish The bombshell came on June 18, 1858. Alfred Russel Wallace sent Darwin a long letter outlining his new theory of species emerging, reaching the same conclusions in an uncanny parallel to the way that Darwin had. Charles Darwin--The Theory In 1859, Darwin published On The Origin of Species. 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. Darwin’s Conclusion--# 1 Natural Selection In a natural setting, through natural selection, any variation (i. e. mutation) 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. Darwin’s Conclusion--# 2 Varieties 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. Evolution -- Fact or Theory? • Since “descent with modification,” Darwin’s idea of 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. Darwin’s Controversy # 1 Natural 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, without divine direction. Darwin’s Controversy # 2 New species could evolve from varieties Second, given the great age of the earth proposed by Sir Charles Lyle, 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 without divine intervention. Darwin was impressed by “the extreme difficulty, or rather impossibility, of conceiving the immense and wonderful universe, including man . . . As the result of blind chance or necessity. When thus reflecting, I feel compelled to look to a First Cause having an intelligent mind in some degree analogous to that of man, and I deserve to be called a Theist. . . . [But then] arises the doubt, can the mind of man, which has, as I fully believe, been developed from a mind as low as that possessed by the lowest animal, be trusted when it draws such grand conclusions.?” (Qtd. in Midgley, Mary. “Purpose, Meaning and Darwinism.” Philosophy Now Jan./Feb. 2009: 16-19.) 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 monkeys; 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. Herbert Spencer The 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. Herbert Spencer The 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.” Herbert Spencer The 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. Herbert Spencer The 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.
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