Theory of Natural selection (scientist)

• Francisco Redi - 1668


  First to refute the idea of 'spontaneous generation' with his maggot experiment
• Francisco Redi - Experiment 


  Placed rotting meat in six jars. Three were covered while three were not. Maggots appeared only in the open jars, suggesting maggots dont spontaneously generate, but enter the meat from outside.
• Louis Pasteur - 1862


  Advanced Redi's meat experiment with his own 'broth experiment'
• Louis Pasteur - Experiment


  Sterilized nutrient broth by heating and sealing the broth in several containers. No bacteria grew in the sealed containers, bacteria grew when the containers were opened, conclusively disproved spontaneous generation.
• Cuvier - Geologist


  Studied different layers of the earth

  Found that different fossils were found in different layers
• Lyell - Geographer + Geologist


  Argued against, castrophism (a few major, sudden changes shaped the earth)

  Believed in uniformitatiranism (slow changes that are still taking place shaped the earth gradually)

  • believed earth was millions of years old
• Lamarck - Zoologist


  First to suggest evolution occurs in some way

  Proposed inheritance through "use or Disuse"

  • organisms would lose under-used traits or enhance useful traits
  • Believed in inheritance of "Acquired Traits"
  • Ex. The children of a person with strong muscles will also have strong muscles when they mature
  • Considered to be incorrect by modern genetics
• Malthus - economist


  Economist who said the human population is limited by its environment

  • Individuals will complete for limited resources
  • population cannot exceed the carrying capacity of its environment
  • Defined as the maximum number of organisms an environment can sustain
• Darwin

  Naturalist for the HMS (her majesty's ship) The Beagle

  Expedition of 1831-1839:

  • Studied many living specimens and fossils along the way
  • Did most important discoveries in Galapagos
  • Finches and Tortoises
• Darwins Observations: Finches

  Observations:

  Different Finches had...

  • different beaks + body size
  • Galapagos finches were similar to South American finches

  Different islands had...

  • different food sources
  • different combination of finches
• Charles Darwin


  Darwin was eventually influenced by many other thinkers:

  Lamarck

  • Species change over time

  Lyell

  • Gradualism and age of Earth

  Malthus

  • Populations compete for resources

  And others
• Conclusions:

  Population of finches emigrated from S.A. to the Galapagos

  Finches spread to different islands

  Each island had different selective pressures

  Different beaks were more advantageous for getting different foods
• Spontaneous Generation


  Since classical times, various peoples believed that living things 'spawned' fully-formed from their environment

  • ex. mice generate from piles of rotting grain
  • ex. frogs generate from muck at the bottom of a pond