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How did life originate?

Explore the theories on the origin of life, from the outdated organic soup hypothesis to newer ideas involving hot springs and extraterrestrial origins. Learn about prokaryotes, stromatolites, and the possibility of life on other planets.

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How did life originate?

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  1. How did life originate? • Old hypothesis: “Organic soup” • Inorganic chemicals like methane, carbon dioxide and ammonia may have been present in Earth’s early atmosphere • Solar radiation, lightning, etc. triggered chemical reactions which formed amino acids – organic soup • Amino acids are the building blocks of proteins – the basic stuff of life

  2. Miller – Urey Experiment • No longer considered valid • No evidence that this was the early composition of the atmosphere • Some evidence to suggest an oxygen-deficient, but otherwise modern atmosphere

  3. Possible Sites for the Origin of Life • Tidal Pools • Clay • Pyrite • Bubbles • Hot springs/Hydrothermal Vents

  4. Newer Idea • Life may have originated near hot springs and volcanic vents • Heat supplied the energy for life processes • Energy also available from chemical reactions

  5. Organisms around a modern black smoker vent

  6. Earliest Life: Prokaryotes • Prokaryotes – cells with no nucleus • Single cells • Strings of cells • Mats of cells - Stromatolites

  7. Earliest Life: Prokaryotes

  8. Cyanobacteria – 3.46 Ga

  9. Modern Stromatolites

  10. Stromatolites

  11. Extraterrestrial Origins of Life? • Ingredients in comets • Evidence from meteorites • Could life have been transplanted to Earth from an extraterrestrial source? • Did life arise on Earth and other planets simultaneously?

  12. Magnetite from Martian Meteorite – evidence of bacteria?

  13. The Allan Hills MeteoriteBacteria(?) from Mars

  14. Life in Stasis: 3 Ga of Single Cells • Life begins – approximately 4.0 Ga • 3.8 Ga – first stromatolites • 3.46 Ga – filaments of cyanobacteria • 1.9-1.7 Ga – at least 12 species of prokaryotes • 1.0 Ga – first eukaryotes • 0.9 Ga (900 Ma) – sexual reproduction • 600 Ma – first multicellular organisms

  15. The Ediacaran BiotaEarliest Multicellular Life

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