

Mirror-Image Cells Could Transform Science — or Kill Us All - VMG
http://www.wired.com/magazine/2010/11/ff_mirrorlife/all/1

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iwwr
It won't wipe out humanity, just potentially plankton-dependent life.

Also, it's not quite so easy to construct a whole mirror cell. The Venter
Institute managed to produce viable synthetic DNA, but that still needed a
natural host cell to provide the cytoplasm and other cell mechanisms. You
can't do that with mirror molecules, you'd have to build it whole, in one go.

As far as we know, building mirror life would be a feat of nanotechnology
rather than chemistry or genomics.

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jerf
There seems to me to be a missing step there; I don't get how mirror bacteria
somehow automatically hoover up all the resources. They'd be in competition
with the normal bacteria, and it is not immediately obvious to me why they so
automatically win. Because, again, this is a mirror competition, so whatever
putative advantage the flipped version has, the normal version has, along with
overwhelming starter advantage. It seems to me there's only really two
possible resulting outcomes, based on symmetry arguments: The flipped versions
still die out, because life favors the already-dominant hand for some reason,
or they compete themselves into a 50/50 standoff because the forces don't
favor either side once they reach parity. Life favoring the side with the
numerical advantage and crushing the other side also happens to explain why we
have one-handed life, so arguably it's the dominant hypothesis at the moment,
too, though I wouldn't care to bet the fate of the planet on it.

Now, the bad thing about the 50/50 case is that it may be a much, much lower-
energy biosphere, because now all life has to deal with the existence of
proteins it can't do anything with and absolutely nothing is evolved to deal
with. Could still be a holocaust of epic proportions with the biosphere not
really recovering for several million years and almost all non-directly-
photosynthesizing life wiped out by starvation as the biosphere has to rebuild
from the bottom. (And by "biosphere recovering" I still mean that we're
basically wiped back to the Great Oxygenation Event [1] in complexity terms,
assuming there's nothing we can do to fix it after the fact.) Could be a
disaster, certainly. But I still don't get the claim that it would somehow
automatically utterly outcompete the existing biosphere.

[1]: <http://en.wikipedia.org/wiki/Great_Oxygenation_Event>

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memetichazard
Wouldn't life favor the flipped version because it has no natural predators?
Consider it an invasive species [1], something there are many examples of and
usually a serious problem. While life may favour existing right-handed life
over developing left-handed life, this does not mean it will favor existing
right-handed life over _developed_ left-handed life - the argument is akin to
saying that an invasive species cannot dominate because it hasn't evolved into
place already.

[1]: <http://en.wikipedia.org/wiki/Invasive_species>

~~~
jerf
Ah, yes, maybe that is what I'm missing. Mentally I have a hard time seeing
bacteria as something that can be preyed upon, but there's nothing impossible
about that, of course, what with the way it happens and all.

(Like so many "tipping point"-type arguments my gut still says that if there
wasn't an advantage to having us all on the same hand, particularly the
ability to pick up correctly-handed molecules out of the environment and use
them, that we'd already live in a 50-50 world; if the system is that
vulnerable to tipping it would already _be_ tipped, so a small dribbling of
cyanobacteria in the ocean will probably simply result in the mirrors dying
off. If life is as easy to start up as it seems to be, it seems like at least
once a mirror life form should have started up. But that's a plausible line of
reasoning, not anything like a proof.)

