3 ms·

Oxygen absorbing isn't necessary, of course. Life on earth got along without it for a while until those darned cyanobacteria starting poisoning everyone else.

• hansbo 6y ago
  Eukaryote life did not appear until after the Oxygen Catastrophe though.
  • madhadron 6y ago
    That's true, but how much earlier might it have occurred if the oxygen catastrophe had not occurred and caused a mass extinction? Hard to say...