NATS 1880 Lecture 6: 06 The Origin and Evolution of Life On Earth
8 Dec 2020
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Chapter 6: the origin and evolution of life on. Some controversy regarding the geologic origin of stromatolites but the variety and commonality of modern mats and stromatolites suggest a strong biologic connection . If correct, stromatolites date life to at least. Photosynthesis (a complex energy generating process) suggests that a more primitive form of life (less complex energy utilization process) must predate stromatolites. Confirming the existence of an ancient microfossil given all of the erosion with time is difficult, indeed controversial. Strong, almost irrefutable evidence of microfossils dating ~3. 0 billion years ago. Less concrete evidence suggests that microfossils date ~3. 5 billion years ago. Isotopic evidence: 12c to 13c ratio reveals the age of life. In geochemistry, this ratio is often found to be around 1:89; however, in life, it seems that organisms do not process 13 c efficiently, leading to a shift in the ratio. In greenland, rocks have been found with a lowered carbon ratio dating to almost.
