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I. Theories and the importance of evolution A. Myths of evolution B. Definition of theory C. Theory of evolution D. Evolution and genetics II. History of Evolutionary Thought A. The Greeks and the birth of Science B. Background of the evolution revolution C. The Evolution Revolution
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I. Theories and the importance of evolution A. Myths of evolution B. Definition of theory C. Theory of evolution D. Evolution and genetics II. History of Evolutionary Thought A. The Greeks and the birth of Science B. Background of the evolution revolution C. The Evolution Revolution D. The Evolution Revolution: 20th and 21st Centuries E. Evolution controversies Theory and History of Evolution
A. Myths of Evolution 1. Evolution is weakly supported by the scientific community 2. There are no transitional forms in the fossil record 3. Evolution is just a theory Theory – a well-documented, explanatory principle 4. Evolution violates the second law of thermodynamics 5. Since the origin of life is unknown, evolution is not valid 6. The evolution/ creationism debate is a scientific debate. 7. Only atheists believe in evolution.
B. Definition of theory Theory: a well-documented, explanatory principle Internal coherence External consistency Unifying power Fertility
C. Theory of Evolution ‘Nothing in biology makes sense except in the light of evolution’ Theodosius Dobzhansky ‘There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.’ Charles Darwin, 1859.
D. Evolution and genetics “Nothing is biology is understandable except in the light of genetics” Phylogenetics
II. History of evolutionary thought A. The Greeks and the birth of Science 2. Plato • Logic 1. Thales • Dangerous Ideas • Archetype • No supernatural 3. Aristotle • No authority Natural philosophy • Scala naturtae
Creation The Flood B. Background to the evolution revolution 1. Biblical creation: Genesis
3. Diversity 18th Century • Scala naturae • Archetype Linneaus
Erasmus Darwin Lamarck Inheritance of acquired characteristics Directed evolution The question of adaptation
Mt. Aetna Hutton Lyell 4. Geology and the age of the earth 18th and early 19th centuries Uniformitarianism The present is the key to the past ‘No vestige of a beginning, no prospect of an end’
Georges Cuvier Relative time scale 5. Extinctions and time scales Index fossils
Charles Darwin (1809 – 1882) Wallace 1859 Galapagos Islands Beagle C. The Evolution Revolution • Voyage of the Beagle • The long interlude: Wallace • The Origin of Species • Evidence from the Origin • Natural Selection • Problems with the theory ‘like admitting murder’ Principles of Geology
3. The Origin of Species The fact and the theory of evolution One long argument 1859
3. The Origin of Species Adaptation and the hierarchy of relatedness Nested hierarchies
3. The Origin of Species No direction Adaptation to local environments
3. The Origin of Species Population thinking
3. The Origin of Species Common ancestry ‘There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.’ Charles Darwin, 1859.
a. Evidence From the Origin i. Domestication Artificial selection Zea mays Teosinte
a. Evidence From the Origin ii. Fossil record Archaeopteryx Neanderthal
a. Evidence From the Origin iii. Biogeography animals and plants of a region are most closely related to those of nearby regions and reflect the history of the region
a. Evidence From the Origin iii. Biogeography Niche
a. Evidence From the Origin iii. Biogeography Cactus Spurge Convergent evolution
a. Evidence From the Origin iv. Imperfections Vestigial organs Wisdom teeth Goosebumps Appendix Cravings: sugar and fat
Evolution is a tinkerer. iv. Imperfections Our textbooks like to illustrate evolution with examples of optimal design ,,,. But ideal design is a lousy argument for Evolution ,,,. Odd arrangements and funny solutions are the proof of evolution--paths that a sensible god would never tread but that a natural process, constrained by history, follows perforce. --Stephen Jay Gould
We could be better iv. Imperfections NATURAL SELECTION CANNOT RESULT IN PERFECT ORGANISMS 1. Historical constraints. 2. Adaptations are often compromises. 3. Not all evolution is adaptive. Genetic drift 4. Selection only edits existing variations. 5. The "Red Queen" effect, a paradox.
v. Homology Embryology: Pharyngeal pouches structure and pathways Gills Eustachian tubes
v. Homology Comparative anatomy analogy Ancestral/ Derived characters
b. Natural selection Darwin’s four postulates 1. Individuals within species are variable. 2. Some of these variations are passed on to offspring. 3. In every generation, more offspring are produced than can survive. 4. The survival and reproduction of individuals are not random: the individuals who survive and go on to reproduce, or who reproduce the most, are those with the most favorable variations. They are naturally selected.
Theory: a well documented, explanatory principle b. Natural Selection • All populations have the potential to overproduce 2. Because of limited resources, no population increases indefinitely 3. Therefore, individuals must compete for limited resources 4. Individuals with variations that allow them to compete successfully for resources will survive and reproduce at a higher frequency 5. If variations (4) are heritable, individuals with those variations will exist at a higher frequency in future generations
Charles Darwin b. Natural Selection Differential reproductive success ‘survival of the fittest’ ‘Descent with modification’ Bonobos
c. Problems with the theory Time Variation The fossil record
Radiation and radiometric dating • Plate tectonics • Cladistics • Fossil Record • The Genetics Revolution • Sexual selection D. The evolution revolution: 20th/ 21st Century
Radioisotopes commonly used in radiometric dating Radioisotope (unstable) More stable product Half-life (years) Useful range (years) Samarium 147 Neodymium 143 106 billion > 100 million Rubidium 87 Strontium 87 48.8 billion > 100 million Thorium 232 Lead 206 14 billion > 200 million Uranium 238 Lead 206 4.5 billion > 100 million Potassium 40 Argon 40 1.25 billion > 100 thousand Uranium 235 Lead 207 700 million > 100 million Carbon 14 Nitrogen 14 5, 730 0-60 thousand 1. Radiation and radiometric dating Radioactive isotopes Absolute time scale
3. Cladistics Cladists clade ancestral Cladogram
4. The fossil record A. sediba Australopithecus afarensis Lucy
5. The Genetics Revolution • Mendelian genetics and polygenic inheritance • Population genetics and the Modern Synthesis • Genetic code and genetic homology • Neutral mutation theory and molecular clocks
e. Genetic technologies Genetic modifications PGD/ IVF Transgenic organisms Human Genome Project
E. Evolution controversies 1. The unit of selection • gene • group • individual • species 2. Tempo of evolution
“… there's something called the scientific process, … involving open publication, criticism, and rejection of things that aren't convincing. We don't teach both sides of the germ theory, of disease and faith-healing. Evolution isn't in the classroom because of political action or court decisions. It's in the classroom because it made it through; it stood up to scrutiny and became the scientific consensus. It fought the battle and won." Kenneth Miller, professor of biology (and devout Catholic)
Scientific support for evolution NABT The rest of the world? NAS AAAS
US Supreme Court Case EDWIN W. EDWARDS, in his official capacity as Governor of Louisiana, et al., Appellants, v. DON AGUILLARD, et al., Appellees. No. 85-1513 October Term, 1986 August 18, 1986 On Appeal From the United States Court of Appeals For The Fifth Circuit AMICUS CURIAE BRIEF OF 72 NOBEL LAUREATES, 17 STATE ACADEMIES OF SCIENCE, AND 7 OTHER SCIENTIFIC ORGANIZATIONS, IN SUPPORT OF APPELLEES Could they be wrong?