The end-the-world scenario is this: A droplet of photosynthetic cyanobacteria escapes into the wild. Since they are immune to natural predators, they take over the niches of oceanic photosynthetic organisms, converting more and more of the planet's photosynthetic biomass to inedible mirror-life. Since ocean photosynthesizes are at the foundation of so many food webs, many ecosystems crash, civilization falls, homo sapiens goes extinct.
Eventually, something will evolve to eat the mirror-life, but by then we'll all be dead.
I'm not buying the idea that simply having mirrored proteins is enough of an advantage for an organism that it would be able to completely out-compete the majority of already existing natural organisms.
I'm not buying the idea that simply having mirrored proteins is enough of an advantage for an organism that it would be able to completely out-compete the majority of already existing natural organisms.
By having mirrored proteins and sugars, such organisms would have no predators or parasites. This condition -- having no natural predators and parasites -- has been replicated many times through the dislocation of species through human transport. Often the result is that such a species is at a huge advantage, much to the detriment of the environment. These are called "Invasive Species." (Asian Carp, anyone? Brown Snakes in Hawaii? Kudzu? Rabbits in Australia?)
Mirrored proteins and sugars would be much worse, since it would be exceedingly hard to evolve an ability to decompose these. I imagine that would happen eventually, but it would take such a long time, our environment would be in shambles and we'd be all long dead.
perhaps I'm just showing my ignorance, but I don't know any examples of invasive bacteria to trust that they'd be a problem in the same way, afaik predator/prey/competition is way more complicated at the micro level.
but I don't know any examples of invasive bacteria to trust that they'd be a problem in the same way
Actually, that makes this even more dangerous. Normally there isn't much scope for invasive species of bacteria precisely because they've been around for a very long time and because they're everywhere. Odds are something has already evolved to eat something else that's similar. Mirror proteins break this. All of a sudden, nothing can eat these new organisms and survive for very long. It would be something unprecedented.
I think evolutionary humility is a great thing to be reminded of, thank you Palomides.
What's interesting to me is, an organism wouldn't have to out-compete the majority of already existing natural organisms to end the world, it "only" need replace the base of the ocean ecosystem. If a new form of bacteria killed all of the krill and plankton it would surely have grave consequences.
Evolution doesn't seek out advantages, it just happens statistically that changes which carry advantages have more probability of rising to fixation within a species. Plus as ptpu touched on (and I'd wager he's more knowledgeable than I am) it's probably hard to even get the necessary mutations let alone having them stick around, or the species lasting long enough, etc.
Note though, this would be really hard to evolve. As an analogy, the photosynthetic center RuBisCO is fairly wasteful, so any organism that can improve on RuBisCO would have a huge advantage. Only problem is RuBisCO is not easily evolvable (like brittle code), thus we don't know of any improvements although they are quite possible theoretically.
This should be trivially fixable. Nobody wants such an eventuality to occur, so the smart money is on wiring in a dependency on some externally supplied, scarce element; for example, ensure that one or more of the enzymes involved in mitosis require a supply of a rare earth element or a purely synthetic (non-biosynthetic, non-natural) organic molecule as a cofactor.
How about this as a scenario: Such safety mechanisms are engineered at first. A rare earth element is used as the cofactor. After a number of years, an organic cofactor is introduced and becomes widely adopted by industry as it reduces costs. Since this works so well, industry becomes cavalier about the release of such organisms, as they all soon die anyways.
A rogue bioengineer creates an artificial organism that can produce the cofactor. Hilarity ensues.
Eventually, something will evolve to eat the mirror-life, but by then we'll all be dead.