[RADIOLAB INTRO]

JAD ABUMRAD: This is Radiolab. I'm Jad Abumrad.

ROBERT KRULWICH: I'm Robert Krulwich.

JAD: Okay, so let me explain to you how I got started with this.

ROBERT: You were at some kind of an affair?

JAD: Yeah. So I'll tell you how—I was at a party.

ROBERT: Party.

JAD: It was a conference where they had a lot of different people with different disciplines come together. You know, one of those. There were panel discussions of various things. So we were at one of the functions, and it was a situation where, like, dinner hadn't yet been served, and there was a lot of booze being served. So everybody was, like, drunk on an empty stomach.

ROBERT: Mm-hmm.

JAD: So I was standing there with some biologists.

ROBERT: Oh, they're the fun ones, the drunk biologists, yes.

JAD: That's my people, apparently. And they started to lose their shit, like, genuinely lose their shit about this thing called CRISPR. And, like, I have never seen scientists this excited about anything. So I was like, "What is this thing? What is CRISPR?" And they were trying to explain it to me but they couldn't slow down enough for me to get it. I gathered it had something to do with genetics. And then at one point one of the biologists turned to me and he was like, "I'll tell you what it is. I can use CRISPR to take a little dog and—poof!—make it into a big dog. Give me a chihuahua, I could turn it into the size of a Great Dane." And I was like, "No, you can't!" He's like, "Yes, I can. I can do it with CRISPR." I was like, "What the hell is this thing?"

CARL ZIMMER: You want me to sit here as usual?

JAD: So what happened was I came back and I immediately called science writer Carl Zimmer because I just figured for this kind of thing, this is a Carl thing. I gotta talk to Carl. So I basically asked him, like, why all the fuss? Maybe it was just the alcohol, or—but maybe there's something really happening here?

CARL ZIMMER: Oh, there's something totally happening here. I mean, it's big.

JAD: He started at the beginning.

CARL ZIMMER: So you can actually find, like, the first reference to CRISPR in a 1987 paper from some Japanese scientists. They basically described something weird in E. coli, and they said, "We don't know what this is."

JAD: E. coli are bacteria inside humans. And like all living things, E. coli is made up of DNA—As and Ts and Cs and Gs. And what happened was that these scientists were reading a chunk of that genetic code when ...

CARL ZIMMER: They found this really strange stretch of DNA.

JAD: Strange how?

CARL ZIMMER: Well so basically, what it was was five identical sequences in a row. And then they were separated by very short sequences in between them that were all different from each other.

JAD: These little blurps. So it'd be like ...

[Beep, beep, beep. Honk! Beep, beep, beep. Honk! Beep, beep, beep. Honk! Beep, beep, beep. Honk! Beep, beep, beep. Honk!]

CARL ZIMMER: And they looked at this and they were like, "What? This is nothing like we've seen before."

JENNIFER DOUDNA: Repeated sequences in bacterial genomes are kind of unusual.

CARL ZIMMER: Seems very strange.

JENNIFER DOUDNA: Some biologists felt that, you know, there must be a purpose for these.

JAD: Among those purpose seekers?

JENNIFER DOUDNA: Jennifer Doudna, University of California-Berkeley.

JAD: She's a cell biologist.

JENNIFER DOUDNA: Yeah.

JAD: So it's Doudna, not Dudna?

JENNIFER DOUDNA: It's Doudna. I used to be called "The Dude," sometimes in school. [laughs]

ROBERT: In the movie, she will be played by Jeff Bridges.

JAD: Right. Anyhow, as time goes on, scientists start seeing these little repeat-blurp-repeats everywhere.

CARL ZIMMER: Yes.

JAD: Or at least in bacteria.

CARL ZIMMER: Lots and lots and lots of species of bacteria. They say ...

JENNIFER DOUDNA: "Hmm."

CARL ZIMMER: "Okay, wait a minute."

JENNIFER DOUDNA: "That's kind of cool."

CARL ZIMMER: They're finding it so often that they decided they had to give it a name.

JAD: And is this where the name CRISPR comes from?

CARL ZIMMER: Yes. The full official name is Clustered, Regularly Interspaced, Short Palindromic Repeats.

JENNIFER DOUDNA: Clustered, Regularly Interspaced, Short Palindromic Repeats.

JAD: Oh my God.

ROBERT: Oh!

CARL ZIMMER: I don't know why they called it CRISPR. It's kind of a ...

JAD: CRISPR. It's like a furniture manufacturer or something.

CARL ZIMMER: It sounds like an app.

JAD: Yeah.

ROBERT: Yeah. CRISPR.

CARL ZIMMER: CRISPR.

JAD: But now scientists had this puzzle.

ROBERT: If nature, at this level, preserves something intact here and here and here and here and here and here, and some of these heres are creatures that have been around for hundreds of millions of years, you figure, well, whatever this is ...

JAD: It's doing something.

ROBERT: ... it's doing something.

JAD: But what?

CARL ZIMMER: It doesn't take very long before the first big clue comes up.

JAD: All right, fast forward. 2005. Now scientists have these big searchable databases of DNA sequences, so some scientists think, "Well, let's do a search. Let's see if these repeating patterns we keep finding match anything else that's out there in the world."

CARL ZIMMER: And these scientists are using computers to just line up these stretches of DNA with thousands upon thousands of different species, and then click—all of a sudden, they discover ...

JAD: That those bits of DNA between the repeats, the stuff in the middle, those blurps ...

CARL ZIMMER: These are matching virus DNA. Like, you can find viruses with genes where these little ...

JAD: So the bacteria had virus inside of them?

CARL ZIMMER: Yep.

ROBERT: Does that mean that a virus brought it into these cells? Does it tell you anything about the origin of it?

CARL ZIMMER: The first recognition was: this is virus DNA. Somehow, all these bacteria have little snippets of virus DNA wedged in these particular places in their genome.

JAD: Which is a little weird if you think about it. I mean, these are totally different creatures. It would be like inside a human finding a little bit of mosquito DNA.

ROBERT: How do we interpret this?

CARL ZIMMER: Well actually, there was one scientist, who's named Eugene Koonin, who looked at these results and just said, "Okay, I get it. It's a defense system."

JAD: [laughs] What?

ROBERT: Why would he think that?

CARL ZIMMER: Because he's a brilliant man!

ROBERT: What do you mean? If I went to a large sanitation dump, and I found a teeny bit of human hair, why would I think, "Oh, I get it. It's a defense mechanism?" I wouldn't know. It's just like a bit of human.

CARL ZIMMER: Right. Well, you see, that metaphor might sort of betray your lack of skill in microbiology. I'm just saying, like, this is not a dump, all right? This is—bacteria are not gonna just let virus DNA get into their genes willy nilly, okay? Remember, viruses are the big enemy.

ROBERT: Right.

CARL ZIMMER: If you're bacteria, viruses make your life a nightmare. Think about in the ocean, okay? The ocean is full of viruses, and viruses kill up to 40 percent of all of those bacteria every day.

JAD: Really?

CARL ZIMMER: Every day.

ROBERT: Oh!

CARL ZIMMER: Yeah. And we know that they have defenses. What Eugene Koonin said was, "Okay, I'm gonna bet that these bacteria are somehow grabbing pieces of DNA from viruses, and then they're storing it. And now they have a way of recognizing those viruses if they come in later."

JAD: Oh!

ROBERT: It's like little Polaroid shots of the enemy.

CARL ZIMMER: Right.

ROBERT: Know thy enemy.

CARL ZIMMER: Yeah, like a "Most Wanted" poster.

EUGENE KOONIN: What you call the mugshot.

JAD: This is Eugene Koonin.

EUGENE KOONIN: Leader of the evolutionary genomics group at the National Center for Biotechnology Information.

JAD: He's the guy that Carl referenced who thunk up the whole idea that maybe these bits of virus DNA inside the bacteria is the bacteria trying to defend itself.

EUGENE KOONIN: What really, if I would credit myself with anything here, it was not so much guessing this because, you know, when you see these identical sequences, that gets pretty obvious. It is figuring out how the mechanism was likely to work.

JAD: So can you walk us through how the mechanism is likely to work?

EUGENE KOONIN: All right. What happens is ...

CARL ZIMMER: You know, when a virus comes into a cell, it just kind of explodes and kind of releases naked genes, basically.

JAD: If you're this bacteria, these things might take over your cells, so you've gotta respond.

EUGENE KOONIN: Most of the time, you have multiple weapons of defense.

JAD: If you've never seen this virus before, usually the first thing you do, says Eugene, is you send out these enzymes that attack the viruses. They're sort of like the ground troops, and they fight really hard.

EUGENE KOONIN: But much of the time they fail, and then no one will hear about you again.

JAD: They're not terribly sophisticated fighters, so very often the virus takes over, the bacteria dies.

EUGENE KOONIN: But there is some non-zero probability that you actually survive the attack.

JAD: If you do, then what the bacteria will do is send in some new enzymes to basically clean up, to go out, find any stray viruses.

EUGENE KOONIN: And then cut the enemy DNA into suitable small pieces.

JAD: And here, he says, is where you get to the storage part: those enzymes will then take those little bits of virus and shove them into the bacteria's own DNA, right in those little spaces between the repeats.

EUGENE KOONIN: Right there and nowhere else.

ROBERT: So I use those spaces in my own DNA as a storage facility?

EUGENE KOONIN: Yes, if you will. You use it as a memory device.

JAD: Because here's what happens: next time that virus shows up, sprays its genes everywhere, now you are prepared. And this is where the CRISPR story really gets going, because instead of sending out the ground troops who are probably gonna get their asses beat, now you can actually send out the big guns. And in fact, what the cell does is it will manufacture these special molecular assassins, and will give those assassins a copy of that little bit of virus DNA it has in storage basically saying, "Here, take this mugshot. If you see anything that matches this pattern, kill it."

ROBERT: And these attackers, do we know what one of them looks like?

JENNIFER DOUDNA: Yep. So we know what the protein looks like. It actually looks—I would describe it a little bit like a clamshell.

JAD: Sort of imagine Pac-Man, but kind of misshapen and rough. And each one of these guys ...

CARL ZIMMER: What it has is a copy of that virus DNA.

JAD: It's got the mugshot.

CARL ZIMMER: That it's kind of waving around. What then happens is that ...

JAD: Whenever the Pac-Man bumps into some virus DNA ...

CARL ZIMMER: It pulls apart the DNA, unzips it ...

JAD: Reads it. If it's not the right one, it goes on. Nope. Uh-uh.

CARL ZIMMER: And if that RNA has the same sequence, then click click, it just locks in.

JENNIFER DOUDNA: And if that happens, then the DNA is trapped, and molecular blades come out.

CARL ZIMMER: And chop.

EUGENE KOONIN: Cutting its head with a mighty blow.

CARL ZIMMER: Yeah.

ROBERT: So this is smart scissors.

JAD: So it's like, "Are you like the thing I got? Are you like the thing I got? You're like the thing I got."

ROBERT: Snip!

JAD: Snip.

CARL ZIMMER: All right, now we're gonna kill.

JAD: Oh, I see.

CARL ZIMMER: Yeah, and it has to be an exact match.

JAD: When scientists first discovered this whole system, they were fascinated.

CARL ZIMMER: They were working it out. They were like, "Oh, okay, then this happens, and this happens, and this happens. Cool!"

JAD: But then, in walks ...

JENNIFER DOUDNA: The Dude.

JAD: ... Jennifer Doudna with a crazy idea. Well, I don't know if it's crazy, but radical.

JENNIFER DOUDNA: This could be an amazing technology.

CARL ZIMMER: This is a tool.

JAD: This is a tool?

CARL ZIMMER: Yeah.

JENNIFER DOUDNA: Right.

CARL ZIMMER: This is a tool that we can use to cut DNA where we want to cut DNA.

JAD: Her basic thought was: why don't we turn this defense into offense? Because these things, they seem to be really good at cutting. And yet they only seem to cut the things that are on their mugshot, so maybe I could just replace what's on their mugshot. So instead of them going after viruses, maybe they could go after a gene that causes Huntington's disease or hemophilia. For example—and this is actually something that's been done—say you had a mouse with something like hemophilia.

ROBERT: Okay.

JAD: This is a disease that's caused by one bad gene. So what you do is you take these little surgeons, you give them the mugshot for the bad gene, then you stick the surgeon with the new mugshot in a mouse ...

CARL ZIMMER: Then you set it loose.

JAD: And just like it's programmed to, it will find that gene ...

CARL ZIMMER: And click click chop. The scissors will end up cutting exactly the gene you wanted to cut.

JAD: So the bad gene's gone. Now the question is: how do you put in the good gene?

ROBERT: Right.

JAD: It turns out actually, according to Jennifer Doudna, that that's actually not as hard as you would think.

ROBERT: Really?

JAD: Yeah. Apparently what you do is just throw this new good gene kind of in the neighborhood of where the old gene used to be. Just in the general vicinity.

JENNIFER DOUDNA: You don't have to get super precise. I mean, it turns out that there are repair enzymes that are probably continually surveying and checking for breaks.

JAD: She says what'll happen is that inside the cell, these repair crews that come along, they'll see the break. They'll see the good gene just sitting there next to the break. They'll be like, "All right. I'll just stick it in."

ROBERT: Put the pretty guy in this space.

JAD: Exactly.

JENNIFER DOUDNA: So we take advantage of a natural repair pathway that cells have.

JAD: They trick both the cutters and the fixers.

CARL ZIMMER: Yeah. Now we're not assassinating anymore. Now we're actually engineering. We've gone from killing to refashioning.

ROBERT: Well, but haven't we been designing genes, doing genetic—a form of genetic engineering for, I don't know, like, 30 years?

JAD: Yes, but not like this.

BETH SHAPIRO: Genome editing technologies have been around for a long time, but none of them have been as powerful as CRISPR is.

JAD: That's Beth Shapiro from UC-Santa Cruz. She was actually one of the biologists that I drunkenly talked to at that thing.

BETH SHAPIRO: Was it a modern art museum? I can't even really remember.

JAD: I don't remember either.

ROBERT: Must have been quite an evening to have the setting be so vague.

JAD: Anyhow, here's how she put it to us: back in the day—this was just like two years ago—you would have these gene editor things. You would take one, put it in a cell ...

BETH SHAPIRO: And what happened before was, you would give it some instructions about where to go. And it might go there, but it might go to somewhere that's kind of related to where that was.

JAD: [laughs] So it's like, "You just take a right at Staten Island." But it takes a left.

BETH SHAPIRO: And not only would it take a left at Staten Island and not find there, but it would have cost you a fortune and taken up six months of your time to get that thing. And now, you know, it's really easy.

JAD: You just give it that mugshot.

BETH SHAPIRO: And it goes. "I'm gonna find that guy exactly."

JAD: So it seems to be pretty precise. And it's cheap. Like, the old tools would set you back about five grand just to use them once. CRISPR? About 75 bucks. And here's the kicker, says Carl, it seems at the moment that you can take these things out of bacteria, stick them into almost any other creature and it still works.

CARL ZIMMER: You can use the same CRISPR system on anything.

ROBERT: Can you, like, do it if corn is vulnerable ...

CARL ZIMMER: Do it in corn.

ROBERT: ... to a certain pest? You can do it in corn?

CARL ZIMMER: Do it in corn, do it in anything. I am waiting for someone to say "CRISPR doesn't work in species X." And I have not heard of that.

JAD: So basically, what you have for the first time in science is this gene-editing technology that is cheap, precise and possibly universal. And Jennifer Doudna says the moment the full impact of that landed on her ...

JENNIFER DOUDNA: I really—I literally had—you know, the hairs on the back of my neck were standing up, just processing the fact that this thing exists, you know, and that you could actually program it to cut DNA. And just like this molecular scissors, and I can just program it and it cuts DNA wherever I want. [laughs]

ROBERT: It is amazing, unless you think about it further—which we will do in just a moment. I feel a cloud coming in over the horizon. Just over there.

JAD: [laughs] Do you see those clouds on the horizon?

ROBERT: I see it's getting sort of dark over there. But we'll be right back.

[LISTENER: Hi. This is Lauren from Atlanta, Georgia. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org.]

JAD: This is Radiolab. I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: Okay, so clearly the possibilities are there to use CRISPR to treat disease, right?

ROBERT: Right.

JAD: But what if you could get a little more fanciful, right? Like, what if you could actually go back in time and resurrect long-lost creatures? I mean, this is something that Beth Shapiro has talked about a lot.

BETH SHAPIRO: We could reconstruct, using a computer, what the genome sequence of the ancestor of all birds was, and that would have been a kind of dinosaur. And then we could use CRISPRs to turn a chicken into that thing.

JAD: Or what if you could take an elephant, and snip snip snip, gradually turn it into its long-lost relative, the wooly mammoth?

ROBERT: No.

JAD: Because they're related. But the genes are similar.

ROBERT: But the wooly mammoth is over.

JAD: Well, right. But if you know the wooly mammoth genome—which they do, because they apparently got it off some bone or some hair.

ROBERT: Yeah.

JAD: Then you could compare the number of differences, use CRISPR to CRISPR out the different parts of the elephant and put in wooly mammoth instead.

ROBERT: If you can, in effect, go backwards in time and make changes, then obviously, I think, you can go the other way, too, right? I mean, humans are good at design. We're designing animals. So it doesn't seem to me to be a crazy notion to imagine parents all over the world wanting—I don't know—taller children. So silencing the short genes and favoring the taller genes. Getting rid of weak muscles and going for stronger ones. And on and on and on. And I don't know where the designing stops.

JAD: We sort of got into all of this with Carl Zimmer, the science writer.

ROBERT: If you can be very, very gene specific, and you learn more and more about genes over time, why couldn't you invent a creature? Why couldn't you make a pig with wings? You might one day get sophisticated enough to do that.

CARL ZIMMER: Well, there's no winged pig lab. You know, the best you can hope for right now is a wooly mammoth lab. And that's down the hall from where the real action is at.

ROBERT: But now there's a hall. And at the end of the hall is a winged pig lab.

CARL ZIMMER: No.

ROBERT: It hasn't been built yet. It may be 20 years from now, but that's what you're looking at.

CARL ZIMMER: Well, I think—but the thing is that then you're ...

ROBERT: Well, what's wrong with this thought? Why shouldn't anyone realize that that's really what we're talking about?

CARL ZIMMER: Well, because you can't make winged pigs, just because of sort of evolutionary barriers, okay?

ROBERT: Well, there's no real reason for pigs to fly except for the joke.

CARL ZIMMER: No. No. Gentlemen, calm down. Calm down! Okay, I don't think that we need a Federal Department of Homeland Pig with Wings Security. I think we're okay there, all right? What we do need is—like, we do need to figure out what are we gonna do about CRISPR in humans? I mean, they're gonna be using CRISPR for cancer, okay? They're gonna take people's immune cells out of their body, and they're gonna use CRISPR to basically allow them to make proteins. They're gonna be able to grab onto cancer cells and attack their own cancer.

ROBERT: Really? Wow!

CARL ZIMMER: Yeah.

ROBERT: Well, you have to be for that. I mean, you have to be.

JAD: Well, I don't know. I mean, are you for it?

CARL ZIMMER: Well, you are tinkering with someone's own body. You are altering their own cells, you know?

JAD: Dude!

ROBERT: Where do I—it's just I can't even—this is me. I don't know if it's a religious thought, or just the thought of a conservative person. But I mean, I grew up in the test-tube-baby era. I now know many wonderful adult formerly test tube babies. And I remember being astonished that—no. So I can't—I don't know where the sacred begins and ends anymore on that particular turf. I guess what I'm instead on is I'm on a Hobbesian view of human beings. That there is something about human beings—including scientist human beings—all human beings, that there's a darkness and a light. There's an angelic side to being human, and there's a very, very difficult side. And as the human beings get more and more power to create and design and essentially create a future, that future will include the imaginations—both light and dark—of humans. And that will be new in the world.

CARL ZIMMER: I don't think it is new, because if you go back to the start of the scientific revolution, someone like Francis Bacon would say explicitly, like, "Science is going to be both about learning about how the world works, and using that knowledge to control it." You know, this has been discovered, this has been published. Everybody knows it exists. If you're gonna say, like, "Okay, now all—we're gonna outlaw this."

ROBERT: I'm not suggesting that.

CARL ZIMMER: Well, what are you suggesting then?

ROBERT: I think we should cringe a little, as opposed to just have a big party.

CARL ZIMMER: Okay. All right. Let's all cringe. Ready? One, two, three.

ROBERT: Don't make fun of me! No, no! That's not fair!

CARL ZIMMER: Now what? We've cringed, and now what? What do we do now?

ROBERT: I don't know.

JAD: Well, we all cringed. If that's what you're arguing for, we cringed too.

ROBERT: No, you cringed meanly, and you cringed with attitude. I am cringing with ...

JAD: I would like to know ...

CARL ZIMMER: Because you're afraid of, like, dragons.

ROBERT: [laughs]

CARL ZIMMER: You're saying, "Oh my God!"

ROBERT: Yes. I'm afraid of dragons now that ...

JAD: Okay. That conversation with Carl was four months ago, and a lot has happened in that time. Because to the question that you asked: where does the sacred begin and end? Well, one of the lines that had been drawn by Jennifer Doudna and others was that we should not use this technology on humans who haven't been born yet. Meaning not on sperm cells or egg cells. Because if you CRISPR, say, an embryo ...

JENNIFER DOUDNA: That is a permanent change, right? That is a change to the DNA that will be passed on to their children.

JAD: And their children's children, and their children's children's children.

JENNIFER DOUDNA: And you can't ask the person if that's okay, because you're doing it before they're born.

JAD: Consent becomes a real issue. And if you imagine making these changes, and they cascade through generation after generation ...

JENNIFER DOUDNA: You could affect the evolution of organisms. And it's—I don't want to say trivial, but it's fairly easy to do it.

JAD: Wow.

JENNIFER DOUDNA: It's kind of profound. I feel it's really profound.

JAD: Profound, but it was just an idea. That is until ...

[NEWS CLIP: For the first time in history, researchers in China have successfully edited the human genome in an embryo.]

JAD: ... Just two months ago, it was announced that a Chinese team ...

[NEWS CLIP: ... from Sun Yat-sen University used a technique called CRISPR ...]

[NEWS CLIP: ... to edit DNA in human embryos.]

[NEWS CLIP: It's a way of hacking evolution itself.]

[NEWS CLIP: Well, this is hugely controversial.]

JAD: Now these embryos the Chinese team had edited, they were created through IVF and they were not viable.

[NEWS CLIP: So these are embryos that are not going to actually develop into a person, so they're going to be discarded anyway.]

JAD: But still, if they could figure it out with those embryos, what's to stop any of us from going further?

[NEWS CLIP: Biologists and bioethicists are sounding an alarm.]

[NEWS CLIP: The scientists face accusations that they crossed an ethical line.]

[NEWS CLIP: That this sort of thing could be sort of a slippery slope towards ...]

[NEWS CLIP: ... towards designer babies.]

[NEWS CLIP: Essentially, genetically engineering the human race.]

JAD: Now that the cringe party had spread and Robert didn't seem like such a loon, we called up Carl again.

ROBERT: Well, we have to revisit because in our Armageddon conversation, in which I believe I was extremely alarmist and you were extremely down-putting, I feel that I should do a small little parade called the—it's not remember the Alamo. It's like, remember China. And you have to—so you should just begin anytime you want, like, getting on your knees and saying how sorry you are, and we can start from there.

JAD: [laughs]

CARL ZIMMER: I'm sorry. So are we actually surrounded by an army of clones with superpowers?

ROBERT: Not yet. Not yet, but I think the dike has been opened. I believe I'm gonna quote somebody who said, maybe a few weeks ago, maybe it was last week even, writing for National Geographic. I think it was—maybe it was somebody named Carl who said that the news from China, and that news was probably the beginning of an entire new era.

CARL ZIMMER: I think I actually said it was a historical moment.

ROBERT: That's right. Yes, that's right.

CARL ZIMMER: Yes. And I still stand by that.

JAD: Do you feel differently now than the first time we talked?

ROBERT: Yeah, that's really the question.

CARL ZIMMER: I don't feel different, actually, because there's really no scientific surprise here.

JAD: He says people have been doing all these CRISPR experiments on all these different mammals ...

CARL ZIMMER: We're mammals.

JAD: This was bound to happen. And in fact, it may be happening more than we think. One account in the journal Nature said that four other Chinese labs are doing this kind of work as we speak. But Carl also told us—which he said was unsurprising too, but I actually find it kind of surprising—that the CRISPR work this Chinese team did, didn't work very well.

CARL ZIMMER: It works, kind of. I mean, in only a few of the cases did they really get exactly what they wanted.

JAD: They tried using CRISPR in about 86 embryos, and they only got it to work right in maybe 28. And in a lot of them, CRISPRs made the wrong cuts and screwed up the cells.

BETH SHAPIRO: And that led them to conclude that this is a technology that's not ready right now for application in the human germ line. And I agree.

ROBERT: Huh.

CARL ZIMMER: We still are in this kind of fortunate position where we can say, "Oh, well, it's dangerous so we shouldn't use it on human embryos." I just don't think that we're gonna be able to sort of find refuge there in, like, 10 or 20 years. In 10 or 20 years, you know, CRISPR will be so sophisticated that people will be able to say, "I can get you the change you want, and I can do it safely. I can guarantee you that you will have human embryos that have the alteration in the particular gene you want." So then what?

JAD: In fact, Jennifer Doudna told us that this experiment—or similar experiments—had been repeated in mice with more advanced CRISPR systems, because apparently, there are many different kinds, and there it was done with almost no errors.

CARL ZIMMER: Sometimes I feel like we're sort of displacing all our ethical concerns onto something that hasn't happened yet. If we really are concerned about what we're doing to the human gene pool, it's already here.

JAD: Take as an example, in vitro fertilization. About 60,000 kids are born a year through IVF, and it's probable that some of those parents chose whether they wanted a boy or a girl.

CARL ZIMMER: And when people started doing IVF, there was a huge controversy. People said this was dangerous, this was unnatural. I don't see people who are unable to sleep at night because of the existence of IVF.

JAD: Yeah.

CARL ZIMMER: You know, now I'm gonna sound like I'm on Robert's side of this. I mean, okay. So ...

ROBERT: It won't hurt. It won't hurt.

CARL ZIMMER: Okay. All right. Here we go.

JAD: Deep breath.

CARL ZIMMER: So you guys know about all the stuff going on in Iceland, where they're looking at people's DNA, and they're looking for disease genes and so on. And when they were looking at these Icelandic people, they found that some people had a gene that protects them against Alzheimer's. It reduces their odds of getting Alzheimer's. Let's imagine your doctor said, "You know, if you'd like, for an extra thousand dollars, we will take these IVF embryos, and we will use CRISPR to give them the Alzheimer-protecting variant. Would you like that? Do you want to add that to your procedure?"

JAD: Sure, yeah.

CARL ZIMMER: "Or would you like your child to face a future of Alzheimer's? Your choice."

JAD: See, here's my thing. Here's my thing with this whole thing. I'm a little bit haunted by the thing you said, which is that when it's not dangerous anymore, what will we do? And I'm afraid we've already answered that question. That it's not a question that's open anymore, because if we're already doing this kind of stuff—and who's gonna say no to that? Who's gonna say no to that?

ROBERT: Exactly. That's what he just was demonstrating. Yeah.

CARL ZIMMER: Yeah.

JAD: We've already answered the question.

CARL ZIMMER: Yeah, we may have.

JAD: Many thanks to science writer Carl Zimmer. He's written many books. You can check them out at CarlZimmer.com or at Radiolab.org. This piece was produced by Molly Webster. We had original music this hour by Erik Kowalski, otherwise known as Casino Versus Japan.

ROBERT: Special thanks to Anna Rascouët-Paz.

JAD: Lee McGuire.

ROBERT: Dr. Blake Weidenhaft.

JAD: Dr. Luciano Marraffini.

ROBERT: Dr. Sean Burgess.

JAD: And Dr. Jin Wei-Shi. I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: Thanks for listening.

[ANSWERING MACHINE: To hear the message again press two. To delete it—start of message.]

[CARL ZIMMER: Hello, this is Carl Zimmer.]

[BETH SHAPIRO: Hi, this is Beth Shapiro.]

[JENNIFER DOUDNA: Hello, this is Jennifer Doudna.]

[BETH SHAPIRO: Radiolab is produced by Jad Abumrad.]

[CARL ZIMMER: Our staff includes Brenna Farrell, Ellen Horne, Dylan Keefe.]

[BETH SHAPIRO: Matt Kielty, Lynn Levy.]

[CARL ZIMMER: Andy Mills.]

[BETH SHAPIRO: Latif Nasser, Malissa O'Donnell, Kelsey Padgett.]

[JENNIFER DOUDNA: Arianne Wack, Molly Webster.]

[CARL ZIMMER: Soren Wheeler and Jamie York. I think I said "Wabster." Let me try it again.]

[JENNIFER DOUDNA: With help from Danny Luis, Kelly Prime and Damiano Marchetti.]

[BETH SHAPIRO: Our fact-checkers are Eva Dasher and Michelle Harris.]

[JENNIFER DOUDNA: Awesome.]

[BETH SHAPIRO: Thank you much!]

[CARL ZIMMER: Later!]

[ANSWERING MACHINE: End of message.]

 

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