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Darwin and Evolution

Darwin and Evolution. Charles Darwin. Son of Robert Darwin, a physician and grandson of Erasmus Darwin, also a physician Was to study medicine, stomach not strong enough Studied Theology, loved natural science. Darwin ’ s Voyage. 1831 - 1836 Naturalist on the HMS Beagle

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Darwin and Evolution

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  1. Darwin and Evolution

  2. Charles Darwin • Son of Robert Darwin, a physician and grandson of Erasmus Darwin, also a physician • Was to study medicine, stomach not strong enough • Studied Theology, loved natural science

  3. Darwin’s Voyage • 1831 - 1836 • Naturalist on the HMS Beagle • Looking for a biblical account of creation • Many specimens collected (hares, tortoise, finches) and observations made that contradicted creationism • Put his ideas into an essay, but sat on it for 20 years for fear of being discredited as a scientist

  4. Earth is young Fixity of species Adaptation due to creator variation- imperfections Observations should confirm view Earth is old Species related by descent Adaptation = random variations in environmental conditions Observations used to test hypothesis Pre - Post Darwinian Views

  5. Descent with modification- as descent occurs through time – so does diversity Explains the unity and diversity of life Living things share common characteristics because they are descended from a common ancestor Higher being created the species Fixity of species Each species has ideal structure and function Evolution versus Creationism

  6. Mid-18th century contributions • Carolus Linnaeus – taxonomy, scala naturae – ladder of life: simple to complex (humans) • Count Buffon – French naturalist, work support DWM • Erasmus Darwin – grandfather – physician, naturalist, work eluded to DWM • All these men’s work opened the door to the thought of evolution but still supported fixity of species

  7. Late 18th century contributions • Georges Cuvier – • comparative anatomy for classification, founded paleontology • Fixity of species supporter • Tried to explain strata of earth was due to catastrophes/mass extinction

  8. Cont. • Jean Baptist LaMarck – • First to believe evolution occurs • Inheritance of Acquired traits – use it or lose it – environment brings about change • Phenotype does not result in genetic changes • Giraffe neck length • Suntan, muscles…

  9. Darwin’s Theory of Evolution • Influenced by Charles Lyell’s Principle of Geology • James Hutton – geological changes occur slowly over time, natural process: EARTH IS OLD • Contradicts Cuvier – due to catastrophes

  10. Natural Selection Charles Darwin and Alfred Wallace • Idea that those organisms that are best suited to their environment will reproduce and pass on their traits • Alfred Russell Wallace – sent Darwin essay on Natural selection before he published his own • Variations (mutations) are essential to natural selection process ex. Independent assortment

  11. Natural Selection • Thomas Malthus – socio-economist – • human population increase faster than food supply: struggle for existence • Each generation of organisms have same reproductive potential, but not all will survive to reproduce

  12. Natural selection • Fitness – ability to survive and reproduce in its environment relative to others • Usually has most resources • Survival of the fittest • Artificial selection – characteristics are selected for and select organisms to reproduce.

  13. Natural Selection • Adaptation – trait that helps organism be better suited for its environment • Flippers – water, wont help on land • Natural selection occurs because certain members of a population happen to have a variation (mutation) that allows them to survive and reproduce.

  14. Darwin’s Theory of Evolution - Evidence • Biogeography – study of range and geographic distribution of life forms on earth • Darwin reasoned related species could be modified based on their environment (ex. Tortoises) • Observed geographical changes 1st hand and collected fossils to support his theory that species are not fixed, but change over time.

  15. Evidence of Evolution • Biochemical evidence • Darwin was not aware of biochemical evidence • Amino acids- cytochrome c (used in electron transport) • DNA/RNA/enzymes – similarities • Introns (junk DNA) • Fossils

  16. Evidence of Evolution • Anatomical structures • Homologous structures - similar in structure but have different function • Vestigial structures – features that are fully developed in one group of organisms but are reduced and may have no function in similar groups • Embryological development – look at dorsal rod (notochord), pharyngeal slits (gills)…

  17. Theory of Evolution • Unifying theory in biology • Large number of observations • have not yet been found lacking or disproven

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