Astronomy 2021A/B Lecture Notes - Lecture 5: Natural Selection, So Small, Rna World
1 Jun 2017
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Geological records and evolution can"t tell us about how earth was created, only how it changed. If we find a fossil of a certain age, we know life originated before that time the fossil dates back to. Can predict that life on earth arose quite early. Three types of evidence: stromatolites rocks that are characterized by a distinctive layered structure. Living stromatolites layers of sediment mixed with microbes. Top photosynthesis, bottom use the waste from the top to make energy. Offers evidence that microbes existed over 3. 5 billion years ago. Microbes would have had to use photosynthesis, which is an advanced process. Therefore, simple life would have been even earlier than that: microfossils difficult because so hard to identify and rocks have changed form over time due to geological processes. Found fossils in a 3. 5 billion y/o rock formation in australia.
