The History of Evolutionary Thought: 1800s

1. The History of Evolutionary Thought: 1800s • Extinctions: Georges Cuvier • Early Concepts of Evolution: Jean Baptiste Lamarck • Developmental Similarities: Karl von Baer • Biostratigraphy: William Smith • Uniformitarianism: Charles Lyell • Discrete Genes Are Inherited: Gregor Mendel • Natural Selection: Charles Darwin & Alfred Russel Wallace

2. The History of Evolutionary Thought: 1800s • Early Evolution and Development: Ernst Haeckel • Biogeography: Wallace and Wegener • Fossil Hominids, Human Evolution: Thomas Huxley & Eugene Dubois • Chromosomes, Mutation, and the Birth of Modern Genetics: Thomas Hunt Morgan

3. The Rise of Geology Smith – Biostratigraphy Hutton – Gradualism Lyell - Uniformitarianism

4. Geologists recognized that change was gradual • William Smith (1769-1839) • Principle of faunal succession • Principle of Stratification - Biostratigraphy • Layers of sedimentary rocks in any given location contain fossils in a definite sequence; • Same sequence can be found in rocks elsewhere • Strata can be correlated between locations • Idea still used today to date rocks

5. Smith created first geological map Smith learned how to recognize the same layers of rocks in England by looking at the fossils they contain.

6. Early geologists organized surface features of the earth into strata based on where certain fossils were found. This early engraving of a mountain depicts strata and the associated fossils

7. Geologists recognized that change was gradual • James Hutton (1726-1797) Scottish farmer and naturalist • Founder of Modern Geology • Theory of Gradualism • Geologic processes that shaped the ancient Earth were not catastrophic but rather imperceptibly slow and can be seen operating around us today. • Geologic Cycle: uplift, erosion, sedimentation • Enormous lengths of time were required to account for the thicknesses of exposed rock layers. • Argued that the Earth must be extremely old.

8. Charles Lyell (1797-1875) • Lyell - British lawyer-turned-geologist • Lyell started his career studying under the catastrophist William Buckland at Oxford. • Became disenchanted with Buckland when Buckland tried to link catastrophism to the Bible, looking for evidence that the most recent catastrophe had actually been Noah's flood. • Lyell wanted to find a way to make geology a true science of its own, built on observation and not susceptible to wild speculations or dependent on the supernatural.

9. Charles Lyell • Catastrophism • Buffon, and later the physicist Joseph Fourier, both claimed that the Earth had begun as a hot ball of molten rock and had been cooling through time. • Fourier argued that the tropical plants of Europe must have lived during those warmer times. • Some geologists suggested that the cooling of the planet occasionally triggered violent, sudden uplifts of mountains and volcanic eruptions. • Charles Lyell attacked Catastrophism in 1830.

10. Charles Lyell • Turned to ideas of James Hutton. • 1790s - Hutton argued that the Earth was transformed not by unimaginable catastrophes but by imper-ceptibly slow changes, many of which we can see around us today. • Geologic Cycle • Gradualism • Earth was vastly old • Observable processes produce small changes that accumulate over time • The earth must be old

11. Charles Lyell • Lyell's version of geology came to be known as uniformitarianism • The processes that alter the Earth are uniform through time. • Like Hutton, Lyell viewed the history of Earth as being vast and directionless. • Lyell had a profound effect Darwin • Darwin envisioned evolution as a sort of biological uniformitarianism.

12. Natural Selection

13. Charles Darwin and Alfred Russel Wallace

14. Darwin and Wallace • Both Darwin and Wallace • Read Thomas Malthus' Essay on the Principle of Population (1798). • Independently developed the idea of the mechanism of natural selection • Darwin • Much more willing to explore the implications of natural selection, particularly in relation to humans

15. Darwin and Wallace • Darwin began formulating his theory of natural selection in the late 1830s but he went on working quietly on it for twenty years. He wanted to collect a wealth of evidence before publicly presenting his idea. During those years he corresponded briefly with Wallace, who was exploring the wildlife of South America and Asia. Wallace supplied Darwin with birds for his studies and decided to seek Darwin's help in publishing his own ideas on evolution. He sent Darwin his theory in 1858, which, to Darwin's shock, nearly replicated Darwin's own. • Common ancestry • Natural selection

16. Darwin and Wallace • Charles Lyell and Joseph Dalton Hooker arranged for both Darwin's and Wallace's theories to be presented to a meeting of the Linnaean Society in 1858. • Darwin had been working on a major book on evolution and used that to develop On the Origins of Species, which was published in 1859. • Wallace, on the other hand, continued his travels and focused his study on the importance of biogeography. • Championed radical social causes and later openly embraced spiritualism • Led to downplay of his importance in evolutionary biology

17. Charles Darwin (1809-1882) • Medical school in Edinburgh • Preferred to study nature • Trained to become clergyman at Cambridge • Invited to serve as unofficial naturalist for HMS Beagle in 1831 • Main job was to be a companion, of equal social rank, for Captain Fitzroy.

18. Voyage of the Beagle Collected many fossils and living organisms Studied geology while reading Principles of Geology by Lyell Uniformitarianism: observable natural processes responsible for events in the past

19. Observations convinced Darwin that life evolved

20. Darwin’s book published in 1859 • On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life • Descent with modification • All species share common ancestry • Changes occur through natural selection

21. Key Concepts • Natural selection: Darwin’s mechanism of change • Adaptations: traits that have evolved by natural selection • Fitness: Ability to produce fertile offspring and get genes into future generations

22. Common descent makes sense of puzzling patterns in nature Homologous trait: similar because of inheritance from a common ancestor

23. Common descent makes sense of puzzling patterns in nature

25. Darwin’s theory has been expanded • Sexual selection • Selection for traits that provide a mating advantage • Genetic drift • Change in frequency of traits due to chance events • Others

26. The History of Evolutionary Thought: 1800s • Early Evolution and Development: Ernst Haeckel • Biogeography: Wallace and Wegener • Fossil Hominids, Human Evolution: Thomas Huxley & Eugene Dubois • Chromosomes, Mutation, and the Birth of Modern Genetics: Thomas Hunt Morgan

27. Natural Selection • Alfred Russel Wallace (1823-1913)courtesy of Charles H. Smith • Thomas Henry Huxley (1824-1895) • Ernst Haeckel (1834-1919) • Edward Drinker Cope (1840-1897) • Henry Fairfield Osborn (1857-1935)

28. The Modern Synthesis

29. The Modern Synthesis • DeVries • Hardy and Weinberg • Fisher • Haldane • Wright • Pearson • Geneticists - Fruit Fly Biologists • Morgan, Chetverikoff, Dobzhansky

30. The Modern Synthesis • Evolutionists • Mayr and speciation • Paleontologists • Simpson • Botanists • Stebbins

31. Alfred Wegener (1880-1930) • Struck by the fact that identical fossil plants and animals had been discovered on opposite sides of the Atlantic. • Since the ocean was too far for them to have traversed on their own, Wegener proposed that the continents had once been connected. • Theory of Continental Drift • Only in the 1960s, as scientists carefully mapped the ocean floor, were they able to demonstrate the mechanism that made continental drift possible — plate tectonics.

32. Gondwanaland

33. Tectonic Plates

34. Recent 1900's Leads to the "Unfinished Synthesis”

35. Recent 1900's • 1953: Watson and Crick - discovery of DNA • Biochemical systematics • Immunology, Proteins, mtDNA, cl DNA, nuclear DNA, RNA types and activities • DNA-DNA hybridization • Nei and genetic distances • PCR and genetic sequencing • Debate over whether natural selection versus neutral evolution better explains change in populations and leads to speciation

36. Recent 1900's • Study of adaptation-using rigourous experimental testing versus idle-Darwininzing • Advances in paleontology - debate over punctuated versus gradual equilibrium • Study of ancient DNA - molecular paleontology • Hubble telescope and Big Bang • Advances in Embryology and Development, links with genetics (hox genes turn on and off developmental pathways), Epigenetics • New developments in systematics and theory of taxonomy

37. The History of Evolutionary Thought: 1900 to present • Random Mutations and Evolutionary Change: Ronald Fisher, JBS Haldane, & Sewall Wright • Starting "The Modern Synthesis": Theodosius Dobzhansky • Speciation: Ernst Mayr • DNA, the Language of Evolution: Francis Crick & James Watson • Radiometric Dating: Clair Patterson • Endosymbiosis: Lynn Margulis

38. The History of Evolutionary Thought: 1900 to present • Evolution and Development for the 21st Century: Stephen Jay Gould • Genetic Similarities: Wilson, Sarich, Sibley, & Ahlquist