4 ms·
It has always been breathable, it just changed for who.
by classified 3y ago
It has always been breathable, it just changed for who.
- s1artibartfast 3y agoThe article and author assumes that the readers are humans, not going to Cellular life forms.
- chasil 3y agoCarbon dioxide was breathable fuel for cyanobacteria prokaryotes. The oxygen was their waste product, and it poisoned them when the concentration grew too high. They had to wait for natural weathering to take the oxygen out of the atmosphere before they had another cycle of flourishing. "Cyanobacteria are a very large and diverse phylum of photoautotrophic prokaryotes... cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxidation Event and the "rusting of the Earth", which dramatically changed the composition of life forms on Earth." https://en.m.wikipedia.org/wiki/Cyanobacteria https://en.m.wikipedia.org/wiki/Cyanobacteria