Science: Mirror life is a potential existential threat to all life on Earth
CONTEXT
We all remember from my award winning post last Nov. 7 at the award winning Snowflake's Forum, Science: Playing with Evolution. As we recall, the two take-home points were:
- Scientists have created synthetic life using a pathogenic goat bacterium to derive a new man-made bacterial species
- Even with the smallest possible number of genes needed for self-replication, that new species of bacterium unexpectedly could still evolve via mutations that arise naturally in nature
The boffins were blown away by the power of evolution in nature. Long story short, any life form, or near-life form like a virus (life-form adjacent?), can evolve.
MIRROR LIFE
Yesterday, NPR broadcast a segment about the developing branch of research devoted to mirror life, something I intuitively believed was impossible and thus I did not take it seriously. Welp ladies & germs (pun intended), I was possibly wrong. NPR interviewed a researcher at, if I recall right, U. Pittsburg, who researches mirror life.
U. Pitt
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L stands for levorotary, for left-handed, and D stands for dextrorotary or right handed, which refers to how polarized light passes through solutions containing L or D molecules. Notice that although an L and corresponding D molecule are chemically identical, one cannot be superimposed on the other, just like your left hand cannot be superimposed on your right hand. To see that, just put one hand on top of the other. See, they do not superimpose.
By contrast with proteins, DNA and RNA are composed of D sugars. Some molecules in living cells are L and some are D. Mirror life would reverse all of that in proteins, DNA and everything else that is L or D in existing life forms. All L molecules in life today could be chemically synthesized as D molecules and D molecules would be made in the L form. Mirror life is a flipped, mirror image form of our current form of life.
The take-home point from the expert in the NPR interview yesterday was this: If a mirror cell ever gets loose in our environment, our chemical form of life has never been exposed to any mirror form of life. That means that if mirror life gets lose in the environment and manages to survive, it might eventually kill off all life on Earth because our form of life has no defenses against mirror life. All hell could break lose.
Research on so-called mirror cells, which defy fundamental properties of living organisms, should be prohibited as too dangerous, biologists said
On Thursday, 38 prominent biologists issued a dire warning: Within a few decades, scientists will be able create a microbe that could cause an unstoppable pandemic, devastating crop losses or the collapse of entire ecosystems.
The scientists called for a ban on research that could lead to synthesis of such an organism.
“The consequences could be globally disastrous,” said Jack W. Szostak, a Nobel-prize-winning chemist at the University of Chicago who helped write a 299-page technical report on the risks of the research.
In an accompanying commentary in the journal Science, Dr. Szostak and his colleagues warned that an organism created with the new technology could cause “extraordinarily damaging consequences for the environment, agriculture, and human well-being.”
Scientists are still debating how evolution landed on this arrangement. In theory, a mirror cell — with left-handed DNA and right-handed proteins — could carry out all the biochemical reactions required to stay alive.
But as far as biologists can tell, mirror cells do not exist. At least, not yet.
In recent decades, chemists have discovered how to make mirror proteins. Researchers have welded together right-handed amino acids to create mirror versions of natural proteins made by our own bodies.
Mirror proteins behave much like their natural counterparts, with one important difference: They take much longer to break down. That’s because the natural enzymes that normally degrade proteins have shapes that are adapted for attacking left-handed proteins.
They [natural enzymes] cannot grip mirror proteins and cut them into fragments. Their failure is akin to what happens if you try to twist open a lid from a jar by turning it counterclockwise, only to discover that the threads on the jar twist in the opposite direction.
Chemists are now trying to exploit mirror proteins, hoping they can be used to create long-acting drugs for diseases ranging from H.I.V. to Alzheimer’s.
In 2022, Yuan Xu and Ting Zhu, two researchers at Westlake University in China, created mirror enzymes that can produce mirror RNA molecules by reading mirror genes. Similar advances have raised the prospect that scientists could eventually make all the parts required to build a mirror cell, perhaps in ten to thirty years.
Kevin Esvelt, a biologist at MIT who studies the risks of biotechnology, had vaguely wondered in the past if mirror cells might pose a risk. As its synthesis became possible, he began to take that risk seriously.
He raised his concerns with biosecurity experts at Open Philanthropy, which funds research on potential threats to humanity such as pandemics and artificial intelligence.
They brought together Dr. Adamala and other researchers working on mirror cells, along with immunologists, plant biologists and evolutionary biologists, to talk about the possible risks.
The discussion felt at first like science fiction to Jonathan Jones, a plant biologist at the Sainsbury Laboratory in Norwich, England. “It took me a while to take it seriously,” he said. (emphasis added)
All that cool stuff aside, I'm not sure how likely mirror life could be a major threat. Some of the reasons for that pop up in the answers to my question to Perplexity about a life vs mirror life competition:
Q: Would mirror life necessarily out-compete our current form of life, or would it either establish an equilibrium with current life forms, or go extinct? I based that question on the fact that our current life form presumably had to complete with mirror life before life on Earth arose, and our current form won that ancient competition.A: .... long, complicated but very reasonable answer .... Conclusion: The outcome would depend on various factors including the adaptability of mirror life, the availability of suitable nutrients, and the extent to which it can evade predation and immune responses. However, the historical precedent suggests that once a chirality becomes dominant, it's unlikely for the opposite chirality to spontaneously emerge and compete effectively. Therefore, while mirror life could pose unique challenges, it's not guaranteed to out-compete or replace current life forms.
Translating that into general audience, mirror life faces a hell of a long battle with life. It cannot eat us and we cannot eat it. As Perplexity points out, mirror life has to evolve starting from a primitive cell able to feed on atoms and molecules it can use. Many, but not all, of those are called achiral molecules, meaning they are not L or D molecules. Examples include oxygen, methane, carbon dioxide, water, salt, hydrogen sulfide and some other very basic molecules that our form of life evolved from on Earth.
That said, making mirror life is an experiment I think humans ought not try to do. The risk of catastrophe, including human extinction, cannot be assessed with sufficient certainty to justify making mirror life.
Sorry for the length of this post. I was fascinated by mirror life and got carried away. My bad.
By Germaine: A pro-regulated science guy
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