Astro 101 11-21

Astro 101 11-21 - Theory supported by discovery of DNA...

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Astro 101 11-21 Life arose 3.85 B years ago, shortly after end of heavy bombardment Evidence from fossils and carbon isotopes Fossils in Sedimentary Rock Relative ages: deeper layers formed earlier Absolute ages: radiometric dating Rock layers of Grand Canyon record 2 billion years of Earth’s History Earliest fossils Oldest fossils show that bacterial like organism were present over 3.5 billion years ago Carbon isotope evidence pushes origin of life to more than 3.85 b years ago Origin of life on Earth Life evolves through time All life on Earth shares a common ancestry We may never know exactly how the first organism arose Theory of evolution Fossil record shows that evolution has occurred through time Darwin’s theory tells us how evolution occurs, through NS
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Unformatted text preview: Theory supported by discovery of DNA, evolution proceeds through mutations Tree of life Mapping genetic relationship has led biologists to discover this new tree of life These genetic studies suggest earliest life on earth resemble bacteria found near deep ocean volcanic vents and geothermal hot springs Miller Urey experiments – basic building blocks form easily Life could have migrated to Earth Venus, Earth and Mars have exchanged tons of rocks, blasted into orbits by impacts Some microbes can survive years in space Brief History of Life 4.4 b early oceans form 3.5 B cyanobacteria release oxygen 2.0 oxygen builds up .5 b Cambrian explosion Necessity for Life Nutrient Energy Water...
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Astro 101 11-21 - Theory supported by discovery of DNA...

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