Ask anyone with so much as a toe in the astrobiology waters and they’ll tell you that the origins debate is a can of worms best left unopened unless you’re writing a thesis in worm physiology. And interestingly, it’s not clear that there was a time in which that wasn’t the case—even back before we could agree where worms actually come from.
Thinking about oxygen leads to interesting places, like the deep, dark, and often bizzare “light-independent” ecosystems of this planet. Think caves, animal guts, underground, and in the deep sea—basically anywhere there’s no light to power photosynthesis. The connection between darkness and oxygen might not be immediately obvious, but take a second to think about where all that oxygen you’re enjoying right now comes from (probably a tree) and it might be a bit clearer where I’m going with this.