Review: Why Evolution Is True

5. The Engine of Evolution

  • Adaptation by natural selection
      1. Starting population has to be variable
      1. Some part of that variation must come from genetic changes
      1. The genetic variation must affect chance of leaving offspring
  • “Richard Dawkins provided the most concise definition of natural selection: it is ‘the non-random survival of random variants.’ “
  • Each adaptation must confer reproductive benefit
    • It is telling, however, that biologists haven’t found a single adaptation whose evolution absolutely requires an intermediate step that reduces the fitness of individuals.”
    • Reproduction not survival is the key
    • Adaptations benefit individual not species
    • Modification of pre-existing features
  • Genetic drift
    • Produces features neither harmful or useful
  • Evidence for natural selection
    • Selection breeding
    • Evolution of bacteria in the lab
      • Also speciation
    • Resistance to dugs and poisons
    • Severe changes in natural environment
      • Beak size of Galápagos ground finches after drought
  • Selection can build complexity
    • IDers argue that such traits, involving many parts that must cooperate for that trait to function at all, defy Darwinian explanation. Therefore, by default, they must have been designed by a supernatural agent. This is commonly called the “God of the gaps” argument, and it is an argument from ignorance. What it really says is that if we don’t understand everything about how natural selection built a trait, that lack of understanding itself is evidence for supernatural creation.”
    • It takes a long time, but life has been on Earth a long time

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  1. […] The variety of life is explained by the Theory of Evolution; the evidence for which is overwhelming. […]

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