Sol 3 is a Class-14 Deathworld on what used to be a thirteen-point scale until they found it.
Not only is the planet very geothermally volatile with active volcanic systems AND feature violent and chaotic weather systems...
"Earth" is the deepest gravity well they've ever witnessed chemical rocketry successfully achieve orbit from.
The biosphere is teeming with pathogens, so much so that the sapient population's own bodies rely on symbiotic microbial colonies in order to digest nutrients among other tasks.
And the macroscopic fauna are ALMOST as scary as the microscopic stuff: every biome packed with highly adapted predators.
At the top of this complex carnal carnival of carnivory, the "humans" who live there are unstoppable pursuit and persistence predators highly naturally gifted in ranged combat that historically used to just WALK their prey to death. The animals which ancient humans consumed could sprint to temporary safety, but humans will catch up, ALWAYS catch up, and the prey will still be tired when they have to sprint again. Eventually the fatigue outpaces them, and humans catch up for the last time. Just walk right up and bash them with a rock, they might not even have to throw it: dinner is ready!
Furthermore, it's not just the highly volatile oxygen that all the animals there breathe... Sol 3's atmosphere also even contains a constant background presence of radon. The biosphere is passively resistant to some levels of radiation. One of the cities was consumed in the fallout cloud of an exploding nuclear fission reactor(they STILL use water to cool their municipal fission reactors even now!), and although the humans fled, the animals that stayed there are FLOURISHING. Deformed and mutated, but thriving.
In one of their multitude of inter-nation conflicts; two cities were consumed in nuclear fire. On any sane world; these areas would be abandoned and the area around them a quarantine zone; the humans obviously not being fully sane, rebuilt and flourish.
This is related to the fact that humans along with most of the inhabitants of Sol3, are highly resilient to damage; of all kinds.
Humans reproduce slowly; but even though they generally reproduce not far above replacement rate, their resilience means their population still grows at an exponential rate. And on top of that; their advances in medical technology are on the verge of massive life extension. Soon they will have to move out into space; the galaxy better get ready for them.
We're also reliant on water and are mostly made out of it. water is such a "universal solvent", it's quite OP. It dissolves so much, that we don't even think about it
We're death breathers, but also basically have acid blood like xenomorphs
One I’ve learned about recently (and used) is potassium permanganate. One of its uses is for improving water quality in fish ponds. It oxidizes basically all organic matter. It can simultaneously knock out algae, bacteria, parasites, hormones, and other excess organic waste. And the pathogens it kills can’t build up resistance to it like they would an antibiotic or poison, so it can be used preventively without creating stronger bugs. You can’t really build resistance to BURNING outside video games.
But that also means that if you add too much, you can just as easily sterilize all life in a body of water, including fish and anything else you want to keep.
AND it means you need to be careful when handling it. If you burn your eyes or your lungs, it makes them stop working!
Aliens would need an oxidizer to metabolize as well, even if that oxidizer isn't oxygen. If they want to actually efficiently get energy out of things, it'll need to be a strong one. Even fermentation is a oxidation-reduction reaction that just doesn't use oxygen.
Humans being the goofy, weird, but kind-hearted cro-magnons of the galaxy/universe is one of my favorite tropes.
Edit: if you want the exact opposite, try They Are Smol. It's an sci-fi, hfy-parody shitpost. Humans have just as much of a instinct for ultra-violence as the other sapient species of the galaxy, if not moreso. However, humans are about half the size and possess about a quarter of the agility, speed and strength of their Dorarizin (big space wolves), Karnakian (big space raptors) and Jornissian (big XCOM vipers) counterparts.
This means humans are utterly adorable and basically seen as cats if cats were intelligent apes.
It also makes everyone else very concerned that humanity's first response is to fuck things, and our second response is to fuck things. They're concerned about our lack of counterbalace (aka a tail) and think we look very wobbly and clumsy. Finally, they're very concerned about the fact that the entirety of the human race falls into the margin of error for the galactic census, which means that, like cats, they baby humans as much as they can without offending people.
They're also very amused (and sometimes very disturbed) by the fact that humans have a significantly higher penis-to-body ratio (still smaller than the aliens, but an alien-sized human would have a ridiculously large penis in comparison) and have a desire to fuck anything that moves (and yes, there is official interspecies smut on the author's patreon lmao).
I love this series so much.
There's also a more serious companion detective series by Frank Leroux (rip :c) called The Smol Detective (he also wrote some other, shorter Smolverse series as well as a standalone series called The Adventures of Iron Hu-man). It's absolutely phenomenal.
Oxygen is so crazy that once microbiology in the ancient oceans started producing it, all life on earth nearly died. Like very nearly sterilized the earth.
At high concentrations, its still fucking awful for us. Easy to forget that the atmosphere is still only 21% Oxygen and 78% Nitrogen. Even setting aside the risks of fire and explosion at higher concentrations, this highly reactive substance degrades the nervous and musculature system.
You wouldn't want to wander around in a fully oxygenated environment for the same reason you wouldn't want to drive your car through a lake of gasoline.
This reminds me of an excellent short story over on r/writingprompts. It's about how humans evolved in the harshest conditions as a forgotten experiment. They emerge and are basically gods.
Reminds me of the short story podcast 'The Truth' episode - "They're Made out of Meat". In fact I think it may have been a short story I once read online beforehand, that they may just have dramatized. (?)
I wonder if you could something like a magnesium atomosphere where if a human it got a hole in their suit it would cause them to burst into flames as the outside pressure forced it's way in then reacted with the oxygen and water in our suit and body
In Becky Chambers' Wayfarer series, there is a species who actually breathes methane. The focus though is less on how that actually happens and more on how they navigate as the only species for whom oxygen is toxic. It's a great series, btw. It's a not-quite-as-optimistic as star trek future, but still optimistic and with a vast range of species who are all intermingling as learning how to get along.
There are anaerobic bacteria that don't need oxygen to survive. That was the norm before The Great Oxidation Event when cyanobacteria started releasing oxygen into the atmosphere during photosynthesis. Prior to that there was very little oxygen in the atmosphere, and anaerobic bacteria ruled the world.
After the GOE the high concentration of oxygen killed off most of the anaerobic bacteria, and what was left were organisms that made a blood truce with oxygen. Aerobic organisms gained incredible power from utilizing oxygen for metabolism, but eventually die from the accumulated damage the oxygen does to them.
Wow, I know so little about this topic and I'm learning all kinds of cool things. Thanks for the comment. I'd never thought about aerobic being the opposite of anaerobic before either.
There were even some found in uran mine pockets, that live off radiation. Others again by reducing metals. It only really needs that sweet electron difference.
The short version is that life needs something that's at least a little unstable in order to extract chemical energy from things.
The post is correct when viewed in a particular light, on a technicality, if you squint. By that same technicality iron rusting is also burning very slowly. They're ignoring the rapidity which is implied by "burning". But yes, oxygen is unstable, oxygen helps burn things, and oxygen is toxic if you get too much at once. Though you'd need to be breathing pure oxygen pressurized to about 1.4 atmospheres, or regular air pressurized to about 7 atmospheres, for that last one to happen. It's a legitimate concern for deep SCUBA divers.
But why does life need instability? Chemical instability is, in basic terms, just stored chemical energy, and that energy wants to be released. The more reactive something is the easier it is to get energy from reactions involving it. There's a balancing act here where more reactive means easier energy, but also more dangerous. Oxygen is in a kind of sweet spot where it's stable enough that it's not generally going to explode or catch fire on its own, but can be coaxed into doing those things in controlled ways with other chemicals to extract energy when needed.
Because our atmosphere is full of oxygen and nitrogen. Oxygen happened to be the chosen option for some reason, probably because nitrogen might not be reactive enough, idk I'm not a biologist or a chemist forget what i said
Antioxidants may help with some of those conditions, but others are based on such underlying dysfunction that it would be like trying to bailing out a boat with big hole in the side. They're just not gonna do anything for you.
They say a planet like earth I'd very rare. Rarer still to find life on one. I believe life is as abundant in the universe as it is here. Which means to me, in our neck of the universe we are an oddity.