Mirror Life Worries | Hacker News Reader

Mirror Life Worries

science.org

45 pointsetiam20 comments

Please future humans, do not build mirror life.

Thanks.

From the point of view of a newly created colony of opposite-handed bacteria, it would be facing an entire planet of really well established mirror life.

yes it seems unlikely that it would be able to outcompete everything already on earth

if it did I would have thought it would have appeared in the past 5 billion years or so

> if it did I would have thought it would have appeared in the past 5 billion years or so

It may have appeared and been outcompeted. That doesn’t suggest its (artificial) reintroduction would again be outcompeted

It does actually, because it implies it fought and lost that battle the first time.

Now, with L-amino life everywhere it would have an even bigger starting problem.

We see this with extremophiles: organisms which can grow in nuclear cooling ponds full extremely badly when transplanted to nutrient rich environments with other, less capable organisms.

There were large extinction events, prob most notable from this was the great oxygenation event that wiped out most anaerobic life. Other than that I can think of stuff like fungi evolving to break down cell walls.

Cyanobacteria reproduce rapidly in sunlight and their numbers are mostly kept in check by viruses. If you bred a species that didn't have any existing viruses there would still be amoebas, flagellates, etc which would use the extra food to reproduced faster and keep the numbers in check, though it would be a big ecological problem. If these couldn't eat them because the new cyanobacteria was mirror life they they'd lock huge amount of carbon from the biosphere as indigestible sugars and starving all other plant life, over the course of maybe a year at the most.

It's possible that humanity could survive by exploiting things like fossil fuels but by default it would be as bad as the extinction that ended the Permian. And certainly most humans would die.

We're protected from this naturally because it takes over a billion years to evolve something as good at reproducing as cyanobacteria from scratch and any biogenisis that were to happen in the modern world would produce something so hapless it would be swiftly out competed for resources. You can't evolve from a regular bacteria to a mirror bacteria, evolution is really bad at making multiple changes at once and this would require changing literally every part of an organism at once.

What a thoughtful comment! I concur that the chance of mirror-life 'evolving naturally' (or "in the wild" let's say) is basically zero, but then I imagined a future cell-printing machine that 'wild' humans might make that prints (maybe at near the atomic level), and that made me wonder whether given such a printer you could just swap to opposite-chirality (mirror) ingredients, and maybe mirror the 3d plan that you're printing? Doesn't seem that far fetched if we ever get printing at a very small scale level? But then I remembered a cell is more like a wave than a static object, so all of the above are probably meaningless ramblings.. but all in the spirit of curiosity!

I am not alarmed by the possibility of mirror life because I think it would be at a disadvantage to all other life on earth at present, so it probably wouldn't get very far. (famous last words!?)

That would definitely be possible but if humans had the kind of molecular nanotechnology that could do that I'd be much more confident in our ability to whip up some phages to counter the threat.

Ever heard of invasive species?

That's the problem. Mirror life may not be a problem for the biosphere in the long run but it could totally be a problem for humans in the short run.

Mirror species can eat the local species, so they have it easy.

Mirror life can only use the fats and a few amino acids of the normal life. All sugars have chirality so they would need some enzymes to east their own mirrored sugars and another set of enzymes to eat normal sugars. Also, most amino acids have chirality and they would have to reverse them or make their own.

So even if someone waste a few gazillions dollars to make mirror life, it would not be able to eat most normal food.

> All sugars have chirality so they would need some enzymes to eat their own mirrored sugars and another set of enzymes to eat normal sugars.

Until mirrored life evolves enzymes to eat non-mirrored sugars, mirrored life will be at a large disadvantage.

But with exposure to our environment, replete with non-mirrored sugars, that sets up strong evolutionary pressure in the direction of finding those enzymes, in addition to the mirrored enzymes they will already have for eating mirrored sugars.

With such evolutionary pressure, it seems plausible mirrored life will evolve those enzymes, even though non-mirrored life appears not to have done so, or at least not retained it. Because there is no equivalent evolutionary pressure for non-mirrored life to eat mirrored sugars.

If mirrored life does evolve those enzymes, due to that asymmetric evolutionary pressure, then instead of being at a disadvantage, the ability to eat both types of sugars might give them a temporary advantage.

> All sugars have chirality so they would need some enzymes to eat their own mirrored sugars and another set of enzymes to eat normal sugars.

Until mirrored life evolves enzymes to eat non-mirrored sugars, mirrored life will be at a large disadvantage.

But with exposure to our environment, replete with non-mirrored sugars, that sets up a large evolutionary pressure in the direction of finding those enzymes, in addition to the mirrored enzymes they will already have for eating mirrored sugars.

With such evolutionary pressure, it seems plausible mirrored life will evolve those enzymes, even though non-mirrored life appears not to have done so, or at least not retained it. Because there has been no equivalent evolutionary pressure for non-mirrored life to eat mirrored sugars.

If mirrored life does evolve those enzymes, due to that asymmetric evolutionary pressure, then instead of being at a disadvantage, it might give them a temporary advantage over non-mirrored life.

It's not so easy to evolve new enzymes, but one of the main hypothesis is that at the beginning of the Carboniferous https://en.wikipedia.org/wiki/Carboniferous the plants invented lignin (that is the browns part of wood, that is mixed with cellulose that is the white part) and nobody knew how to eat eat, so for 50 millions years the dead trees accumulated on the floor and later transformed to the current mineral coal.

Also cellulose and starch are very similar, they are chains of glucose, but bounded slightly different. We can split only starch, but we don't have enzymes to split cellulose, were "we" includes cows and a lot of animals that would really love to digest cellulose.

I think some bacteria can digest weird sugars, even the mirrored versions, but they are more efficient digesting usual sugars.

For a great sci-fi treatment of the dangers of mirror life, see Fantastic Four 5-6 (2023) by Ryan North. Yes, that Ryan North, and no, it's not your "typical" comic book.

I've heard that his Hulk run is also excellent.

Anyway, Peter Watts' Rifters series is another excellent take on the genre, although it's not mirror life per se. (And it's ... not a happy read.)

Question to any biologists. Do we need to worry about mirror viruses or just mirror bacteria?

A mirror virus would not be able to infect normal cells. Viruses depend on (chiral) host cell machinery such as ribosomes to reproduce.

Thank you.

Hopefully mirror antibiotics are earlier in the tech tree than mirror life.

Reply on news.ycombinator.com