Then things started to turn sour. As populations boomed, food, inevitably, became scarce. Pressure to survive intensified. The full article is available in the 7 August issue of New Scientist magazine. See below for details.
Oxygen literally burns cells from the inside out.
It grabs electrons to create free radicals, those highly reactive chemicals that wreak havoc within cells. For a while at least, some materials in the environment neutralised the corrosive newcomer. Iron, dissolved in seawater, formed rusty hematite and sank to the ocean floor. But, eventually, the iron ran low, oxygen built up and life started drowning in its own waste. Hordes of bacterial revellers died on the spot.