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CSU ANTH 120 - Darwin's Theory

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BIOM 121 1nd Edition Lecture 2Outline of Last Lecture I. Origins and Variation II. AnthropologyIII. Scientific TheoryIV. Ancient Greek Concept of EvolutionV. Linnaeus (1758): Categorizing Life FormsOutline of Current Lecture I. Notions of Earth's TimelineII. The Problem of FossilsIII. CatastrophismIV. LamarckismV. Darwin's VoyageVI. After the VoyageVII. Natural Selection 1. Notions of Earth's Timeline a) The Young Earth Hypothesis states that the earth is about 6000 years old.- Widely subscribed to in 1700s- Archbishop Ussher, Lightfoot, and Kepler all arrived at this conclusion, based on information from the Bible b) Ideas of Deep Time begin to take shape in geological community.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Steno creates Law of Superposition in 1699, which says that the oldest rock layers (strata) are on the bottom and youngest are on the top.- Arduino in 1759 identifies 3 unique rock layers.- James Hutton (1795) states that the earth is in a state of constant and gradual change; it is not static.- William Smith (1769-1839) creates biostratigraphy, the first dating method for fossils.- Combined with Law of Superposition to date fossils in separate strata relative to one another c) Charles Lyell (1797-1875) founds modern geology with his Principles of Geology, published 1831-1833. - These principles include Uniformitarianism, or the uniformity of:- Law: Natural laws remain constant through time- Process: Past events were caused by the same factors that present events are, i.e. flooding- Rate: Change is slow and steady- State: Change is not directed or goal-driven- This all led to the realization of the need for Deep Time to explain the Earth's development.- Now, Earth's age is estimated at 5-4.8 billion years old- Necessary for the slow process of evolution, as evidenced by fossils 2. The Problem of Fossils a) Early fossils were confusing and included giant reptiles, tiny horses, inland marine creatures, and tropical tree bark imprints in Iowa.- Many were of extinct creatures, with some of them resembling extant organisms b) Two pre-Darwinian hypotheses developed.- Fossils present evidence of extinction, but there are no evolutionary connections between past and present species (catastrophism)2- Fossils present evidence of species in mid-evolutionary development, but species never go extinct (Lamarckism) 3. Catastrophism a) Georges Cuvier (1769-1832) founded vertebrate paleontology and distinguished fossils as extinct organisms.- Worked with fossils from the Paris Basin, where he identified many extinct species such as Parisian mammoths, elephants and whales- Thought that fossils, along with being evidence for extinction, demonstrated that past and present species are not identical (true) and that they are not related (untrue)- Created Catastrophism, the non-evolutionary hypothesis for extinctions: catastrophic past events wiped out animals in certain places, where they were replaced by completely different species.- He was NOT an evolutionist, and supported the ideas of species immutability and spontaneous generation. 4. Lamarckism: Theory of Evolution by Means of Acquired Traits a) Jean-Baptiste Lamarck (1744-1829) founded invertebrate paleontology and created the opposite hypothesis; species changed over time, but didn't go extinct.- Argued that species are not immutable and are always changing over time (correct)- Ascribed to theory of orthgenesis, that species were always striving to become “higher” (incorrect) b) Theory of Evolution by Means of Acquired Traits- Adult organisms can will the fluids in their bodies to create new body parts or improve others, in order to respond to environmental challenges. - Disuse will cause the body to reabsorb the modifications.- Acquired traits are then passed on to offspring.- Example: Giraffes stretching out their necks to reach higher leaves, then creating longer necks and passing that along to their children.c) There are problems with this theory:- Relied on the concept of orthogenesis and a linear, goal-driven evolution- Would result in less population variation, because all organisms would have the same traits in response to the same challenges- Flat-out doesn't work!But he did introduce solid foundations for ideas of heredity and the relationship between organism and environment.5. Darwin's Voyage a) Before the voyage, Darwin was a Lamarckian. The theory was accepted by many, including Darwin's grandfather Erasmus. b) The voyage, on the HMS Beagle, lasted from 1831-1836. Captain Robert Fitzroy hired Darwin to collect research specimens. c) Darwin collected data on many diverse environments, and extant and extinct species- Saw rainforests, deserts, grasslands, forests, mountains, islands- Studied animal behaviors and extinct fossil organisms- Giant ground sloth, giant armadillo, giant Toxodon (rhino/elephant/horse)- These fossils showed that South America had been home to many giant mammals species, part of a worldwide phenomenon with the biggest mammal being in Asia 38-5 mya- Also found inland marine fossils- Environmental data included volcanic eruptions, earthquakes and tsunamis d) The Galapagos Islands provided the perfect place for arctic and tropical fauna, with high diversity.- Marine iguana, blue-footed boobies, raptors, and distinct finch species filling different niches in their habitat - Darwin learned that there is much variation in nature, applying to:4- Geology, geography, and habitats, interspecies and intraspecies, extinct and extant, continental vs island, habitat community6. After the Voyage: 1836-1859 a) By 1837 Darwin had rejected the Scala Naturae in favor of an evolutionary tree.- Idea that all organisms share a single, ancient common ancestor, which forms the trunk, with all other branches being divergent species b) By mid-1840s, Darwin is writing about the natural selection mechanism of evolution.- Influenced by Lyell's Principles of Geology, but his theory was mostly unprecedented and went against the prevailing Lamarckism beliefs.- Conducted additional research about barnacle anatomy, earthworm behavior and soil turnover, artificial selection (he did pigeon breeding), and population thinking c) Influenced by Thomas Malthus' Principle of Population: - Malthus was a clergyman and


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CSU ANTH 120 - Darwin's Theory

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