Darwinian Evolution

• Evolution 


  "descent w/ modification" - darwin's words

  all spp (species) descend from ancestral spp
• Pre-Darwinian Ideas

  • before darwin, there were ideas on why life is so unique/variable
  • start with Aristotle
• Aristotle (1)

  • came up with scale of nature
  • This scale was the idea that spp follow rungs of ladder (as you go from bottom rung to higher rung you become more complex)
  • NO evolution
  • nothing states that spp evolved, they were just there and had specific rungs for each spp
• Judeo-Christian Culture (2)

  • culture based off of old testament
  • believed in creation
  • NO evolution
  • eventually, natural theology develops within culture
  • Natural theology : individual interested in science based on religion itself
• Carolus Linnaeus (3)

  • natural philosopher
  • developed a binomial nomenclature system
  • developed hierarchical classification system (you have rungs of ladder but there is hierarchy. never explicitly stated evolution but he hinted at it)
• George Cuvier (4)

  • french paleontologist & natural theologian
  • studied fossils in paris
  • in his studying, he saw rock layers
  • rock layers showed spp disappear + new ones appear not seen in previous layer
  • deeper the "strata", more dissimilar flora + fauna
  • basically he is saying : deeper you go within rock layer the more different you see the plant of that rock layer compared to what they're right now on earth and all the animal things
• George Cuvier (4)

  Proposed theory of catastrophism

  • many followers because the theory was rooted in religion but had scientific basis (fossils)
  • stated each change in rock layers was due to/equal to major catastrophe (ex: noah's flood)
• Pre-Darwinian Ideas 


  James Hutton (5)

  • scottish geologist
  • developed gradualism
• Gradualism


  land forms are results of mechanisms currently operating

  • means everything we see on earth today is due to things like erosion, volcanic activity, and flooding
  • wasn't catastrophes rather gradual build up of these natural mechanisms which caused the rock layers having diff spp
• Charles Lyll (6)

  • geologist
  • refined version of gradualism
  • wrote doctrine of uniformitarianism
  • this idea states geological processes are uniform (balance eachother out)
  • (ex: formations of mountains is balanced out by its counterpart which is erosion)
• Jean Baptiste de Lamarck

  • studied fossils, saw lines of DESCENT from older to younger spp
  • FIRST to propose a mechanism for evolution
  • his idea was based off of principal of use and disuse
  • created the inheritance of acquired characteristics (1809)
• Principle of use and disuse

  • parts of body which is often used becomes longer and stronger (better version because you use it so much)
  • he believed in the ex of the giraffe neck
  • Parts not used begin to disintegrate
  • he wasn't exactly right, but close
• inheritance of acquired characteristics

  • individual (organism) passes on acquired characteristics from their lifetime to the next gen
  • example: giraffe; ancestor of giraffe had a short neck and because of this, it acquired a long neck (principle of use + disuse). This longer neck went to next gens, now giraffes have long necks.