Short Wave - Mirror cells could threaten life on Earth. Why are we building them?

Episode Date: August 10, 2026

For people with two hands, one is usually dominant. On a molecular level, earthly life takes this to the extreme. All of the DNA in living things twists to the right, whereas the protein building blocks favor a kind of left-handed chemistry.The rules of life are based on this chemistry.In recent years, scientists have worked toward a kind of mirror version of life. Currently, the technology doesn't exist to make mirror life at the cellular level — and likely won't for at least a decade. Still, a group of scientists is concerned enough about the possibility that they've published a 299-page technical report calling for a stop to the science.In this encore episode for our Tech Camp series, host Regina Barber talks to Carl Zimmer, a science reporter at The New York Times, about his reporting on mirror cells — and why creating them could lead to devastating consequences for life on Earth.Check out Carl's full article.Curious about other controversial research? Email us at [e-mail] public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey everyone, Regina Barber here with another installment of our summer series Tech Camp. And it's just for you. Because it's Monday. And every Monday through mid-August were dropping episodes about the frontiers of tech, tracking down the breakthroughs, experiments, and innovations that could change everything. Today, that means checking out cells. And I don't mean the ones that make up you, me, or every living thing you see.

see, nope, it's something different that gets two very different reactions from scientists, that it's either the future of biology or possibly the end of life as we know it. Okay, let me back up. 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 working on this story, I learned about a whole new level to that. Handedness affects the very building blocks of life. All of life on Earth picks aside. 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 handiness 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 research. 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. 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, that chemistry should all work in the mirror.

But we don't know that. 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 cell. even though it's likely a decade away at the earliest. At this point, it's not just science fiction. 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. 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?

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, 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's kind of like a slow moving infection. The 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, you know, proteins that are twisting the other way, it's as if these cells are invisible. So these mirror cells will just keep growing and growing and growing and growing until, you know, 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 you're, 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 these 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. They get 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. 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 now, 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, you know, 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. skull. 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, well, let's stop and think about this and what we're doing. But by then, the technology had

been created. More recently, people have heard of CRISPR, which is a way to actually edit DNA. And there again, you know, scientists did get together and meet and have been talking about the ethics of this. But really, you know, they only started talking about it after they had created the technology. 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 like 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 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 they should 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? Actually, one member of this team that's warning about mirror cells, Kate Atomala, she is among a group of scientists who have actually. have been working towards mirror cells. They thought that mirror cells would be cool.

And they had grants from the U.S. government and elsewhere to work on the steps you need to take to get to creating a mirror cell. Now they still expected it to be decades away, but they can see the path. And Kate Atomala, after thinking about this and talking about this and talking with her colleagues said, you know what, this is not worth it. And she had, she has shut that program down. 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 like be a matter of debate now that this warning has come out. And I think you, you will see

public meetings happening over the next year where a lot of, you, you know, scientists and people with other kinds of expertise are going to be getting together to talk more about this. You know, are they are they being hysterical? Are there actually real benefits? We'll see. But right now, I, 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? You know, there are lots of things to worry about in our everyday life.

Yeah. A mirror cell killing you is not something to worry about because they literally do not exist on Earth. Right. Right. And if scientists are dealing with this transparently and thinking about, well, maybe we should do this at all, then, you know, you don't have to worry about getting infected with a mirror cell in 50 years. Like it just, as far as we know, mirror cells on Earth will not exist if scientists don't make

them. So there you go. Thank you so much, Carl, for bringing us the story about mirror cells. I definitely learned a lot. Thank you. Excellent. Thanks for having me. Before we head out, if you liked this episode, remember to hit the follow button.

That way, you'll never miss another episode of Shortwave. And if you have the time, leave us a review. It helps out the show. This episode was produced by Jessica Young and Burley McCoy. It was edited by a showrunner Rebecca Ramirez and fact-checked by Tyler Jones. Quasey Lee was the audio engineer. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm the regular Regina Barber, not the mirror Regina Barber. Thanks for listening to Shorewave from NPR.