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  1. Starter Organise the organism at your table with the other tables in the order that they evolved. When you are finished stand that order at the front of the classroom

  2. Lesson 13: Theories of evolution Objectives: State Darwin’s theory of evolution Describe some of the evidence that evolution has taken place Identify the differences between Darwin’s theory and conflicting theories (ex. Lamarck’s)

  3. Evolution

  4. The Tree of Life • All living things share a common ancestor. • We can draw a Tree of Life to show how every species is related. • Evolutionis the process by which one species gives rise to another and the Tree of Life grows

  5. Evolution as Theory and Fact • Confusion sometimes arises as to • whether Evolution is a theory or a fact. Actually it is both! • The theory of Evolution deals with how Evolution happens. Our understanding of this process is always changing. • Evolution is also a fact as there is a huge amount of indisputable evidence for its occurrence. Rodin’s “The Thinker”

  6. Discovery (1) Fixed species Michelangelo’s fresco on the ceiling of the Sistine Chapel From Classical times until long after the Renaissance, species were considered to be special creations, fixed for all time.

  7. Discovery (2): Transmutation • Around 1800, scientists began to wonder whether species could change or transmute. • Lamarck thought that if an animal acquired a characteristic during its lifetime, it could pass it onto its offspring. • Hence giraffes got their long necks through generations of straining to reach high branches. Jean Baptiste de Lamarck

  8. Discovery (3): Fossils and Strata ImageWilliam_Smith.g.jpg Geological_map_of_Great_Britain.jpg William Smith, his geology map & some of his fossil specimens At about the same time, geologists like William Smith were mapping the rocks and fossils of Britain. He and others showed that different species existed in the past compared with today.

  9. Discovery (4): Darwin’s Voyage • From 1831-1836, a young naturalist called Charles Darwin toured the world in HMS Beagle. • He was dazzled by the amazing diversity of life and started to wonder how it might have originated Voyage of the Beagle

  10. Discovery (5): Survival of the Fittest • In his Origin of Species, • published in 1859, Darwin • proposed how one species • might give rise to another. • Where food was limited, • competition meant that only • the fittest would survive. • This would lead to the natural selection • of the best adapted individuals and • eventually the evolution of a new species. Natural Selection explains adaption Darwin in 1860

  11. Discovery (6): Huxley v. Wilberforce • Darwin’s idea of • Evolution by Natural • Selection was met with • huge controversy. • A famous debate in • 1860 pitted Bishop • Wilberforce against • Darwin’s bulldog, • Thomas Henry Huxley. Bishop Wilberforce v. T. H. Huxley • Evolutionists got the better of the debate, but few were convinced • by Darwin’s idea of Natural Selection.

  12. Discovery (7): Genetics • From 1856-63, a monk called GregorMendel cultivated 29,000 pea plants to investigate how evolution worked i.e., how characteristics were passed down the generations. • He figured out the basic principles of genetics. He showed that offspring received characteristics from both parents, but only the dominant characteristic trait was expressed. • Mendel’s work only came to light in 1900, long after his death Mendel and his peas

  13. Discovery (8): Making Sense • In the early 20th century, scientist started to make sense of how evolution worked. • Building on Mendel’s genetics, studies showed how characteristics in a population could be selected by environmental pressures. • This Modern Synthesis, as Julian Huxley called it, brought Darwin’s Natural Selection back to the centre of evolutionary theory. Julian Huxley and the Modern Synthesis

  14. Discovery (9): Opposition • Despite the achieval of scientific consensus on evolution, some Christian groups continued to oppose the concept. • In 1925, the teaching of evolution was outlawed in Tennessee, USA, resulting in the infamous • Scopes Monkey Trial Outside the Scopes Trial

  15. Summary • Biological evolution: Descent with modification. All life on Earth shares a common ancestor. • Jean-Baptiste Lamarck: In 1802 published that an animal acquired a characteristic during its lifetime, it could pass it onto its offspring (transmute). • Charles Darwin: published Origin of Species in 1859:Where food was limited, competition meant that only the fittest would survive. This would lead to the natural selectionof the best adapted individuals and eventually the evolution of a new species • GregorMendel (1863): He figured out the basic principles of genetics but his work wasn’t recognised until 1900’s. • Creationists: Believe that all life was made perfect and separately.

  16. Main Evidence of Evolution: • Fossils • DNA • Morphology: a)Homologous structures: Inherited from a common ancestor. (ex four limbs in the mouse, bird and human) b) Analogous Structures: Haveseparate evolutionary origins, but are superficially similar (ex. Wing in bat and bird)

  17. Evolution produces a pattern of relationships among lineages that is tree-like, not ladder-like. • There is no correlation with level of "advancement”. Biologists often put the clade they are most interested in (whether that is bats, bedbugs, or bacteria) on the right side of the phylogeny. Misconceptions about humans • It is important to remember that: Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human. Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split, humans and chimpanzees have each evolved traits unique to their own lineages.