Dating the emergence of life on Earth is a daunting task. We can date when life was already thriving based on the age of microfossils, i.e., mineralized structures whose size, shape, and chemical composition matched those of modern microbes. But even these ‘proofs’ can be misleading. In the 1980s, for example, scientists discovered 3.5-billion-year-old mineralized filamentous structures in the Apex Chert formation in western Australia, which were strikingly similar to cyanobacteria. The ‘microfossils’ were later shown to be inorganic mineral formations. So far, the oldest microfossils may be the carbonaceous spheroidal microstructures of the Moodies Group in South Africa (3.2 billion years old) and microfossils from the Strelley Pool Formation in Western Australia, which are believed to represent 3.4-billion-year-old sulphur-metabolizing cells. Hence, the microfossil data supports the notion that life was already thriving in the mid-Archaean eon. But how far back in time does life go?...
Posted on: Tue, 08 Apr 2014 19:27:08 +0000
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