Oxygen Holocaust

This was by far the greatest crisis the earth has ever endured. Many kinds of microbes were immediately wiped out. Microbial life had no defence against this cataclysm except the standard way of DNA replication and duplication, gene transfer and mutation. From multiple deaths and an enhanced bacterial sexuality that is characteristic of bacteria exposed to toxins came a reorganisation of the superorganism we call the microcosm. The newly resistant bacteria multiplied, and quickly replaced those sensitive to oxygen on the Earth s surface as other bacteria survived beneath them in the anaerobic layers of mud and soil. From a holocaust that rivals the nuclear one we fear today came one of the most spectacular and important revolutions in the history of life. 

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