2, Young and Zimmerman, History of Earth Timeline

  • (5 BYA) Sun

    (5 BYA) Sun
    Sun ignites, solar system takes shape
  • (4.6 BYA) Earth

    (4.6 BYA) Earth
    Molten Earth forms, lacks oxygen
  • (4 BYA) Ocean

    (4 BYA) Ocean
    Ocean forms, organic molecules join the water and create amino acids. nitrogen bases, carbohydrates, and hydrocarbons
  • (4 BYA) Moon, Crust

    (4 BYA) Moon, Crust
    Moon forms by collision, Earth forms solid crust
  • (3.5 BYA) Prokaryotes

    (3.5 BYA) Prokaryotes
    Prokaryotes form, marine photosynthesis begins
  • (3 BYA) Respiration

    (3 BYA) Respiration
    Respiration develops in mitochondria
  • (2.2 BYA) Oxygen

    (2.2 BYA) Oxygen
    Rapid rise in oxygen
  • (2 BYA) Oxygen

    (2 BYA) Oxygen
    O2 levels reached today’s levels
  • (1.5 BYA) Eukaryotes

    (1.5 BYA) Eukaryotes
    Eukaryotes form with a nucleus
  • (1 BYA) Ozone Layer

    (1 BYA) Ozone Layer
    Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land
  • (1626) Francesco Redi

    (1626) Francesco Redi
    Francesco Redi’s experiment showed that flied are attracted to rotting meat, but don’t come from it.
  • (1665, 1673) The First Microscopes

    (1665, 1673) The First Microscopes
    Hooke invents first microscope in 1665; Leeuwenhoek improves microscope in 1673
  • (1700's) Lazzaro Spalanzani

    (1700's) Lazzaro Spalanzani
    Lazzaro Spalanzani Showed that microorganisms don’t generate spontaneously either
  • (1822) Louis Pasteur

    (1822) Louis Pasteur
    Louis Pasteur used a curved-neck flask to show that even when the broth is exposed, microorganisms will not generate in the broth, but rather collect at the U-bend in the neck.
  • (1924) Oparin's Hypothesis

    (1924) Oparin's Hypothesis
    Oparin’s hypothesized that early earth contained ammonia, hydrogen gas, water vapor, and methane. These high temperatures, along with lightning and UV radiation gave way to macromolecules such as proteins and eventually life forms.
  • (1952) Miller-Urey Experiment

    (1952) Miller-Urey Experiment
    Miller-Urey experiment studied the possibility of life in early-earth conditions, testing Oparin's Hypothesis.
  • (1960's) Lynn Margulis

    (1960's) Lynn Margulis
    Lynn Margulis proposeds that early prokaryotic cells developed an endosymbiotic relationship.
  • (1960's) Sidney Fox

    (1960's) Sidney Fox
    Sidney Fox did research on the physical structures that could have given way to the first life forms.
  • (1970's) Thomas Cech

    (1970's) Thomas Cech
    Thomas Cech studies transcription of a cell’s nucleus
  • (1970's) Radiometric dating

    (1970's) Radiometric dating
    Radiometric dating developed to find out how old organic specimens are.