Lecture 181 The History of Life on Earth2 Part 1

Apuntes

Lecture 18: The History of Life on Earth: Part 1 Reminder: Quiz 7 - Wednesday 1) Geological Time Scale 2) Origins of Life 3) Oxygen Revolution 4) Origin of Eukaryotes 5) Origins of Multicellularity OUTLINE: Imagine... That all of Earth History is compressed into a single day... https://www.youtube.com/watch?v=H2_6cqa2cP4 Life on earth https://www.youtube.com/watch?v=H2_6cqa2cP4 • When did life first arise? And in what form? • What about multicellular organisms (metazoans)? • The invasion of land from the sea? • Mammals? • Humans? First multicellular organisms 5:00 accumulation of free oxygen 10am The major points being............. • Life evolved under anaerobic conditions • Much of the history of Life has been in the forms of prokaryotes and single cell eukaryotes (single cells) • Multicellular organisms are relatively recent • Mammals then humans have inhabited this planet for a VERY SHORT time Life on Earth - Atmospheric Oxygen Concentrations Have Changed Over Time Evolution of large vascular plants Cataclysmic geological events Biotic changes • Early Earth atmosphere contained little or no free oxygen gas • About 2.5 bya ances...