GGR101H1 Lecture Notes - Lecture 4: Cambrian Explosion, Archaea, Louis Pasteur
26 Jan 2017
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Lecture 4: from our earliest ancestors to late glacial maximum: supereons, eons, epochs, ages, periods. Precambrian supereon: formation of life to first hard-bodied organisms, 90% of geological time, hadean, archean, proterozoic eons, very little remains, last universal ancestor. 4600 to 540 mya: stable crust by 4. 4 bya. Uranium-lead isotopes in zircon found in continental crust. Can trace all life back to lua: bacteria, archaea split 3300 mya. Cell nucleus and membrane: sexual reproduction 1200 mya. Removal of harmful mutations, transmission of resistances: first great extinction 2300 mya. First time oxygen appears in atmosphere as organisms start generating oxygen: eukaryotes emerge between 2100-1600 mya. Aerobic life evolves, anaerobic life dies: rodinia supercontinent. Creatures arise from living matter present in inanimate objects. Molecules become amino acids which gradually become more complex. Recreated early earth conditions, electrically charged water, created amino acids. Cambrian explosion: first fossilized life, paleozoic (540-485 mya, tempo of evolution.
