All life known to us has left-handed DNA.
Or, stated technically, “all life on Earth builds proteins only out of left-handed amino acids.”
Which “poses a tantalizing scientific puzzle: Couldn’t you, in principle, build ‘mirror life’ — life made out of the right-handed amino acids?”
A Vox story (read it here) says, “It would be an enormous engineering project, involving work we don’t yet know how to do. But in principle, it ought to be possible. We have already built mirror proteins, and mirror enzymes that can read mirror genes.”
Suppose, instead, an alien life form “made out of right-handed amino acides” survived entry through our atmosphere and crash-landed on earth, then met — and tried to eat — normal life forms as we know them.
Would this be like antimatter colliding with matter? Not exactly. The left-handed life form wouldn’t go “poof” with an enormous release of energy. It would simply get eaten. And, recent scientific work indicates, wouldn’t be able to eat back.
This means a “mirror” life form (say, in the form of bacteria) “could be kind of like introducing an invasive species to an ecosystem (in this case, the entire planet) where it doesn’t have any predators.” And having no predators, it would multiply, until it took over the entire ecosystem. In an Earth overrun by right-handed bacteria, everything would get sick, every animal, every plant.
The result, scientists say, “could be terrifying. They concluded, “We cannot rule out a scenario in which a mirror bacterium acts as an invasive species across many ecosystems, causing pervasive lethal infections in a substantial fraction of plant and animal species, including humans,” and added that “unprecedented and irreversible harm” is a plausible outcome.
Consequently, scientists are rethinking whether efforts to synthesize “mirror life” in the lab are too risky. But what if someone uses the technology to create a life-eradicating bioweapon? Or what if an alien probe carrying mirror life lands on our planet?
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