There is a growing body of evidence which suggests that the evolution of the planet drives the evolution of the biosphere. There have been 2 significant stages in Earth history when atmospheric oxygen levels rose rapidly, and both appear to be associated with supercontinent cycles. The earlier biospheric event, which extends across the Archean-Proterozoic boundary (ca.
View Article and Find Full Text PDFThe discovery of evidence indicative of life in a Martian meteorite has led to an increase in interest in astrobiology. As a result of this discovery, and the ensuing controversy, it has become apparent that our knowledge of the early development of life on Earth is limited. Archean stratigraphic successions containing evidence of Earth's early biosphere are well preserved in the Pilbara Craton of Western Australia.
View Article and Find Full Text PDFStructures resembling remarkably preserved bacterial and cyanobacterial microfossils from about 3,465-million-year-old Apex cherts of the Warrawoona Group in Western Australia currently provide the oldest morphological evidence for life on Earth and have been taken to support an early beginning for oxygen-producing photosynthesis. Eleven species of filamentous prokaryote, distinguished by shape and geometry, have been put forward as meeting the criteria required of authentic Archaean microfossils, and contrast with other microfossils dismissed as either unreliable or unreproducible. These structures are nearly a billion years older than putative cyanobacterial biomarkers, genomic arguments for cyanobacteria, an oxygenic atmosphere and any comparably diverse suite of microfossils.
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