We and all other animals wouldn’t be here today if our planet didn’t have a lot of oxygen in its atmosphere and oceans. But how crucial were high oxygen levels to the transition from simple, single-celled life forms to the complexity we see today?
We and all other animals wouldn’t be here today if our planet didn’t have a lot of oxygen in its atmosphere and oceans. But how crucial were high oxygen levels to the transition from simple, single-celled life forms to the complexity we see today?