For people with two hands, one is usually dominant. On a molecular level, life takes this to the extreme. All of the DNA in earthly living things twists to the right, whereas the protein building blocks favor a kind of left-handed chemistry. But in recent years, scientists have worked toward a kind of mirror version of life. The technology to make mirror life likely won't exist for at least a decade. Still, a group of concerned scientists published a 299-page technical report calling for a stop to the science. New York Times science columnist Carl Zimmer explains how a mirror microbe could wreak havoc on life on Earth in the future. Check out the full technical report and Carl's full article.Curious about other controversial research? Email us at [email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave. Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy
Chapter 1: What is the significance of handedness in life?
So, I'm right-handed. Not everyone is. My whole life I've heard the woes of my left-handed friends that the world is just not made for them. And recently, I learned about a whole new level to that. Handedness affects the very building blocks of life. All of life on Earth picks a side.
The building blocks for our DNA... They're all right-handed. They could be left-handed, but they're not. And that's just a rule across all of life.
That's Carl Zimmer. He's an author of many books on science and a reporter for the New York Times.
I'd say my beat is life, basically what it is and what it could become.
This handedness of molecules and life is called chirality. It's the mirror image of a molecule, like how your face is flipped in the mirror. On Earth, all the DNA we see, aside from some transient exceptions, all the helixes turn to the right. And so far, scientists haven't seen any evidence that life is ambidextrous either.
But in the last decade, researchers have been getting closer and closer to understanding how life can be on the other side of that mirror. by creating mirror molecules, like in pharmaceutical drugs, some of which are even in clinical trials. Since enzymes in the body didn't evolve to recognize mirror molecules, the thought is that these drugs last longer.
But Carl says manufacturing these molecules can be a painstaking process. Like, say a scientist hypothetically wanted to manufacture mirror insulin in the hope it lasts longer.
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Chapter 2: What are mirror cells and why are they important?
Now, if you want to make mirror insulin, there's no cellular factory around that you can use to make those molecules. You have to make them by hand, basically.
Unless you make a mirror cell. That cell could make those mirror molecules. And he says seeing a mirror cell, a form of mirror life, would just be cool.
I mean, no one has ever seen a mirror cell. Ever. As far as biologists can tell, the chemistry should all work in the mirror.
Right now, scientists can't even make a regular cell from scratch, much less a mirror cell. But many scientists do see a path to mirror cells, even though it's likely a decade away at the earliest.
And that worries some scientists.
So much so that dozens of biologists published a 299-page technical report on the feasibility and risks of creating mirror cells, claiming that this kind of research could potentially lead to devastating consequences for life on Earth.
They could potentially create a kind of a pandemic that's almost like science fiction. It would potentially be a total catastrophe, not just for humans, but for maybe all animals and maybe all plants and maybe all ecosystems.
So today on the show, how mirror cells could threaten life on Earth, what it would take to actually make one, and what it means for a scientific community to call for a stop on a technology before it's ever made. I'm Regina Barber, and you're listening to ShoreWave, the science podcast from NPR.
I'm Tanya Mosley, co-host of Fresh Air. At a time of sound bites and short attention spans, our show is all about the deep dive. We do long-form interviews with people behind the best in film, books, TV, music, and journalism. Here our guests open up about their process and their lives in ways you've never heard before. Listen to the Fresh Air podcast from NPR and WHYY.
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Chapter 3: How could mirror cells pose a threat to life on Earth?
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So, Carl, at the end of 2024, like a group of biologists issued a warning against studying mirror cells. And you reported on this for The New York Times. Can you help us like paint a picture of what exactly they're afraid of happening?
Chapter 4: What risks do scientists associate with mirror cell research?
Their big worry is that scientists would create a mirror cell. One of these cells gets out. Maybe it actually just infects someone working in the lab. It gets into their bodies. it's possible that even though it's a mirror cell, it may be able to find some food inside of our bodies and so that it can actually feed and grow.
You would start to have this mirror cell slowly dividing inside of your body. So you can sort of imagine it as kind of like a slow-moving infection. Problem is that our immune systems are evolved to recognize life on our side of the mirror. And if they're coming up against cells that have proteins that are twisting the other way, it's as if these cells are invisible.
So these mirror cells would just keep growing and growing and growing and growing until they kill the first person they infect. And then all of a sudden you have this person just rife with these mirror cells. They infect other people. And on and on and on, you have this uncontrollable pandemic.
And I mean, we're talking about like worst case scenario with humans, but we could even take a step back and be like, this could hurt plants. This could hurt animals. You know, this could affect our agriculture, right? Like what would a scenario like that be? Same, right?
Basically, if the scientists are right, any species that might be vulnerable to microbes and infections could be totally helpless against a mirror cell. So plants get lots of infections. Lots of bacteria get into them. And they have all sorts of sophisticated ways of fending harmful bacteria so that they can grow and survive and give us food.
And that all falls apart if you're dealing with a mirror cell, as far as plant biologists can tell, because the plant defense systems are all tuned to life on our side of the mirror.
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Chapter 5: How do mirror cells potentially impact ecosystems?
That said, this hypothetical scenario won't happen tomorrow. There are definitely some big steps that would need to happen before any of this could become a reality. What are the hurdles to scientists making a mirror cell?
So as of now, scientists have figured out how to make some mirror proteins. They have been able to make a mirror enzyme that can build some mirror RNA. And of course, cells are made of a vast number of parts. And so it's a long way to go before anyone is going to put a mirror cell together.
So what's the landscape right now on, like, just making a functional cell in the lab?
Scientists are creating very simplified versions of cells from synthetic parts. And so these have a membrane. They have an inside and outside. You can put some molecules inside of them. Those molecules may do some of the things that happen inside of our own cells. These are not full-blown cells, however. So just how far you have to go to actually boot up a cell is just a fundamental question.
But there is a whole community of scientists who are going towards this goal. They sometimes call themselves the build a cell group. And they're headed in this direction. And, you know, they keep steadily making more progress. And so while no one is about to make a cell from scratch today, I don't think you can be assured that they won't be able to do it in 20 years.
So these scientists are calling for like a stop to this science before it's been even created. Like how unique is that?
I think that this is actually unprecedented. In the 1970s, scientists invented recombinant DNA where they could take pieces of DNA and insert them into the genes of bacteria. And they were already starting to publish results on this where you could get bacteria to make human proteins. And then a group of scientists said, whoa, whoa, let's stop and think about this and what we're doing.
But, you know, by then the technology had been created. More recently, people have heard of CRISPR, which is a way to actually edit DNA and And there again, scientists did get together and meet and have been talking about the ethics of this. But really, they only started talking about it after they had created the technology.
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Chapter 6: What current advancements are being made in mirror cell research?
And so now we're in a situation where the scientists have done enough work that they can see down the road and say, you know, we might be able to make this. It doesn't exist yet. So let's think about what would happen if it existed. And if we think it's a bad idea, let's not do it. So I don't know of any case where this has happened before.
And if the call to stop this science works, we might not need to worry about this potential threat?
We surely don't need to worry about it today because it doesn't exist. And as scientists have these conversations and other stakeholders get involved, if we can come to sort of a global agreement, then... then this won't come to be. I mean, it's not easy to make a mirror cell. You cannot make a mirror cell in your garage.
And so there's an opportunity here for a conversation to really think about what would be the risks and what might be the benefits of making mirror cells and then making a decision about whether to make it or not.
So even with this warning, how popular is research into creating mirror cells? You said it hasn't happened yet, but like who's working on it and how many people are working on it?
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Chapter 7: What challenges exist in creating a functional mirror cell?
Actually, one member of this team that's warning about mirror cells, Kate Ademala, she is among a group of scientists who actually have been working towards mirror cells. They thought that mirror cells would be cool and they had grants from the US government and elsewhere to work on the steps you need to take to get to creating a mirror cell.
Wow.
You know, I have not talked to any scientist who has said after this warning came out, yeah, I'm going to go ahead and do it anyway. I think that this is going to actually be a matter of debate. now that this warning has come out.
And you will see public meetings happening over the next year where a lot of scientists and people with other kinds of expertise are going to be getting together to talk more about this. Are they being hysterical? Are there actually real benefits? We'll see.
But right now, it looks to me like if anybody is really excited about doing a mirror cell project, it's probably not looking good for them to get that next grant.
Okay. How worried should, like, let's say a regular listener be about mirror cells?
Really?
Yeah.
You know, there are lots of things to worry about in our everyday life.
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