BIO 115 Lecture Notes - Lecture 9: Isotopic Signature, Type Inference, C3 Carbon Fixation
Document Summary
Carbon isotopic signatures used in infer diet of early hominids. C4 plants have lower c13 than c3 plants. C13: not heavier but more difficult to incorporate into plant tissues. C12/c13 ratio can be used to infer types of plants eaten. Used as a biomarker for a life form. Key piece of evidence tracing biological patterns in fossil records. Humans have switched from heavily c3 plants to c4. Oldest evidence of life dates back to 3. 7 bya. Scientists search for evidence of life in old rocks. Oldest stromatolite (bacteria) fossils date back to 3. 45 bya. Earliest life unlikely to be preserved in fossils. Very unusual and unlikely circumstances that there would be any fossilization at all of the early life evidence. Presence of carbon in early rocks suggests life. Biomarkers are molecular evidence of life in the fossil records. Isotopic signature distinguishes from lifeless carbon sources. Look for biomarkers of early forms of carbon use.
