Over 2.5 Billion Years Ago It Was Really Bad

There was no oxygen.

Oxygen makes up 21% of the Earth’s atmosphere, and we need it to breathe. But early organisms would have found this environment toxic. Ancient bacteria evolved protective enzymes that prevented oxygen from damaging their DNA, but what evolutionary incentive did they have to do this? Researchers have discovered that ultraviolet light hitting the surface of glacial ice can release molecular oxygen. Bacteria colonies living near this ice would have needed to evolve this protective defense. They were then well equipped to handle the growth of atmospheric oxygen produced by other bacteria that would normally be toxic.

Here’s the whole thing: How Did Early Bacteria Survive Poisonous Oxygen?

I’ve made jokes about the news reports in The Bacterial Times regarding the toxic Oxygen that was appearing in the atmosphere. No doubt the UBN (United Bacterial Nations) was discussing ways to reduce their oxygen footprint…

Early bacterium discovers that its clone is an O2 denier…