[RADIOLAB INTRO]

LULU MILLER: All right, so Latif.

LATIF NASSER: Yeah?

LULU: What are we doing today?

LATIF: We're gonna go on a hunt.

LULU: All right?

LATIF: That actually starts in my car.

LULU: [laughs] All right.

LATIF: I was with my two kids. I think at that point my kids were six and three, maybe? And the U2 song "The Sweetest Thing" comes on. Do you know that song?

LULU: Of course!

LATIF: Da da na na na na.

LULU: Yeah, of course. It's a bop.

LATIF: Yeah. It's my favorite of their songs.

LULU: Yeah.

LATIF: And my kids, who have never heard the song before, they're listening to the song. And they ask, "What is the sweetest thing?"

LULU: Did you try "love?" Were you like "love?"

LATIF: Yeah. No, my kids, they don't care about that. They were just like, "No, no, no, but what really is the sweetest thing?"

LULU: So just what's the sweetest thing I can get in my mouth?

LATIF: Yeah. They're kids, they love sugar.

LULU: Yeah, of course.

LATIF: Right now they're obsessed with gummy bears. And they just wanted to know is there some other thing out there we've never had before that's even sweeter?

LULU: Hmm.

LATIF: So I figured, like, I'm a journalist. I can answer this.

LULU: Well Latif, bless your amazing children—who I adore. Do you care about this question?

LATIF: Yeah. Yes.

LULU: Why?

LATIF: Because—okay. Because it sounds like a dumb, simple question.

LULU: Or not a dumb question, but it seems like it has an answer, and then you're like, "Son ..."

LATIF: Yeah, I kind of expected it would be that way too.

LULU: Yeah.

LATIF: But then this question turned out to be so much more, more than just a hunt for, like, a substance. It became like this thing where I was trying to get to the edge of human experience. And sweetness as one of those experiences is this basic, familiar thing that we all know. It's like almost mundane, but I kept finding that, wait a second, like, no, no, no, the edge is even further to these levels of sweetness that I didn't even know existed in the first place. And there's some mind hacks and brain lasers and space raspberries. There's a lot of fun stuff along the way.

LULU: All right. All right, let's go.

LATIF: Okay, all right. So the very first thing that I found, right off the bat, I found all these scientists ...

LATIF: Check, check, check.

ERIC WALTERS: Okay.

LATIF: Hey! Okay!

ERIC WALTERS: Hello!

LATIF: ... who are out there, trying to answer—rigorously scientifically—this exact kid question.

ERIC WALTERS: My name is Eric Walters.

LATIF: Okay. Can I call you Eric?

ERIC WALTERS: Please do. You don't have to "Doctor" me.

LATIF: Like Eric here, a biochemist who used to work at NutraSweet, where he developed artificial sweeteners.

ERIC WALTERS: I spent a lot of my career working on sweeteners, studying sweeteners and ultimately writing a book about sweeteners.

LATIF: And what scientists like Eric in the food industry do is they find or even make new sweet molecules.

ERIC WALTERS: Yeah. Yeah. Tweaking the structure in small ways and seeing, does it get better or worse?

LATIF: And then they literally rank them in terms of sweetness.

ERIC WALTERS: Yeah.

LATIF: And they keep, like, a list of the sweetest things on Earth.

LULU: Oh!

LATIF: And I want to walk you up my top five of the list, using table sugar as our baseline here.

ERIC WALTERS: Because that's the most common sugar that we use every day.

LULU: Okay, great.

LATIF: So number five: honey. You know honey.

LULU: Heard of it.

LATIF: Honey is about 1.5 times sweeter than sugar.

LULU: Which what does that mean? It's just—it's just—what does that mean?

ERIC WALTERS: So typically in the food industry, people do this with trained taste panels.

LATIF: These specialized taste testers who are really good at noticing differences in sweetness.

ERIC WALTERS: I haven't done it in years, but I used to be very good at it.

LATIF: And here's what they generally do: They take a little sugar.

ERIC WALTERS: One gram of sugar.

LATIF: Like a pinch.

ERIC WALTERS: Dissolve it in water.

LATIF: Call it a cup of water. Taste it.

ERIC WALTERS: Sip and spit.

LATIF: Then they mix the same amount of the thing they're testing—let's say, in this case, honey—with the same amount of water, and again ...

ERIC WALTERS: Sip and spit.

LATIF: To see which is sweeter.

ERIC WALTERS: Yeah.

LATIF: Now to be able to say how much sweeter this thing is than sugar, what you do is you just add water ...

LULU: Until it's the same?

LATIF: Until it's the same. So, like, with honey, you would theoretically need to add 1.5 times as much water for them to taste the same. Then you can say it's 1.5 times as sweet.

ERIC WALTERS: Yeah, there you go.

LULU: Okay, that's a good way to, like, come up with a scale.

LATIF: Yeah.

LULU: Okay.

LATIF: Okay, so that was honey. Honey was number five on the list. Now, one level sweeter, number four ...

ERIC WALTERS: Aspartame.

LATIF: Aspartame, which is used to sweeten Equal.

LULU: Sure, okay.

ERIC WALTERS: It's about 200 times as sweet as sugar.

LATIF: So it takes 200 times more water ...

LULU: Wow! So just gallons.

LATIF: ... with aspartame to taste the same as a cup of sugar water.

LULU: That's wild!

LATIF: Yeah. Next, number three. This one actually comes from nature.

LULU: Ooh!

LATIF: This is a katemfe fruit, which is a little red berry that grows in West African tropical rainforests.

LULU: Huh!

LATIF: And it is 2,000 times sweeter than sugar.

LULU: Oh, orders of magnitude.

LATIF: Yeah. But then, number two: advantame. How sweet? Just take a guess.

LULU: 5,000.

LATIF: Advantame is 20,000 times sweeter than sugar.

LULU: Oh my gosh!

LATIF: That means just a pinch of advantame could sweeten 500 gallons of water. That's like a jacuzzi of sugar water.

LULU: That's freaky.

LATIF: Yeah. Okay, number one. The number one sweetest thing, according to these expert sweetness sippers sitting around in their food labs is Lugduname.

ERIC WALTERS: Yeah.

LATIF: I don't even know how to pronounce it. Lugduname?

ERIC WALTERS: I always say "Lugdanayme." But ...

LATIF: Lugduname.

LULU: Okay.

LATIF: This is 300,000 times sweeter than sugar.

LULU: Oh!

ERIC WALTERS: Yeah. That's what we said.

LATIF: Oh my God!

ERIC WALTERS: Yeah, that's—that's insane.

LULU: Okay, so what is this?

LATIF: This is a swimming pool. This is almost a full swimming pool.

LULU: Wow!

LATIF: What was the mood and the reaction at NutraSweet to this news?

ERIC WALTERS: I was jealous.

LATIF: Yeah.

ERIC WALTERS: Wish I'd thought of that. [laughs]

LATIF: Because, in his line of work, they're always trying to push this limit a little bit further.

LULU: Right.

ERIC WALTERS: I discovered a sweetener that was 28,000 times as sweet as sugar.

LATIF: Interesting.

ERIC WALTERS: So I didn't win. I didn't win the prize on that one.

LATIF: But the prize goes to this, like, Frankenstein of a molecule called Lugduname.

LATIF: Okay, so sit down.

FAVEL: The wise man.

LATIF: You want a very little amount of this one, okay? You ready?

LATIF: So I set up a little tasting for my kids.

LATIF: Huck—yeah, that's a good amount, Huck. Favel, too much.

LATIF: I couldn't actually get my hands on any Lugduname, because it turns out it's not FDA approved for human consumption, because apparently if you try it, there's a chance it turns your blood the color of chocolate.

LULU: What?

LATIF: But ...

LATIF: Why don't you guys drink some water?

LATIF: I did give them some Advantame, number two on our list.

LATIF: Okay, ready guys?

HUCK: Ready!

LATIF: And ...

[Children coughing and wretching]

LATIF: Oh, okay. What do you think?

HUCK: Ugly.

LATIF: Ugly?

[Child crying]

LATIF: You spat it out all over the floor? Okay, Huck is now scraping his tongue with his fingers. What are you doing? No, don't. No, no, no. Don't spit on the couch. That's gross, man. That's gross. That's gross.

LULU: So the thing that scientists say is 20,000 times sweeter than sugar doesn't actually taste sweet?

LATIF: Yeah.

LINDA BARTOSHUK: Now, isn't that remarkably dumb?

LATIF: [laughs]

LATIF: According to psychologist Linda Bartoshuk, this whole ranked list is ridiculous. Like, this is the dumbest way to measure this.

LULU: Huh!

LINDA BARTOSHUK: Have you ever heard anybody say that saccharin is a hundred times as sweet as sugar?

LATIF: Yes.

LINDA BARTOSHUK: Have you ever tasted saccharin and sugar at the same time?

LATIF: No.

LINDA BARTOSHUK: Well, I assure you, you will not think the saccharin is a hundred times as sweet as sugar, for God's sake.

ERIC WALTERS: Well, these—these sweeteners, they do have some off flavors.

LATIF: Eric says that the problem with coming up with a perfect sweetener is that there's only one sweetness receptor, but on the other hand ...

ERIC WALTERS: Humans have, I don't know, 20 or 30 bitter taste receptors.

LATIF: So it's like a minefield that you have to kind of tiptoe through to get to the promised land of the sweet receptor.

ERIC WALTERS: Yes, yes.

LATIF: So, it's really hard to develop a compound that triggers the sweet receptor but doesn't trigger any of the bitter receptors as well, which is why you get those off tastes from so many sweeteners.

LULU: Right.

LATIF: But the food chemists, when they're ranking sweeteners, they are just looking at one very specific thing.

ERIC WALTERS: And that's a value that we refer to as "potency."

LATIF: They just want the thing you can use the smallest amount of to turn on that sweetness receptor.

LINDA BARTOSHUK: The weakest thing you can just taste as sweet.

LULU: Got it. Okay.

LATIF: And that kind of measurement is very, very helpful if you are a soda company or making chewing gum or something, and you have a giant vat of something. And ...

LULU: And you want to put in the least amount of a thing to make the most money.

LATIF: Putting the least amount of that thing, right?

LULU: Right, right.

LATIF: But that's not what my kids are asking. That's not what I'm looking for. We're looking for a whole other thing.

ERIC WALTERS: And that's intensity of sweetness, how sweet does it actually taste to you?

PAUL BRESLIN: Yeah, I think that's right. Because we're talking about sweetness, and sweetness is a perception.

LATIF: This is Paul Breslin.

PAUL BRESLIN: Professor in the Department of Nutritional Sciences at Rutgers University.

LATIF: And he says, you know, with things like advantame, right? You might think that if you just kept adding more and more of it to the water, it would ...

PAUL BRESLIN: Keep getting sweeter and sweeter and sweeter until it went to the moon. But it wouldn't. You'll eventually reach a point where the sweetness intensity sort of reaches a plateau.

ERIC WALTERS: The amount of sweetness that you perceive sort of levels off.

LATIF: The thing is that our sweetness receptor, it's not just like a regular light switch you turn on or off. It's more like a dimmer switch.

LULU: Okay, sure.

LATIF: So it can get brighter and brighter. And these sweeteners, they can only get a certain amount of bright.

LULU: Huh!

LATIF: So what we really want to know is: What thing will turn that dimmer switch up the highest?

LULU: To the brightest bulb.

LATIF: What will get you the brightest bulb?

LULU: Okay.

LATIF: And according to Eric, by that measure ...

ERIC WALTERS: Maybe sugar is the sweetest thing there is.

LATIF: No!

ERIC WALTERS: Because it can get you to a higher perceived intensity of sweetness.

LATIF: He's never heard of or tasted anything sweeter than sugar.

LULU: Wait, so is that the answer? The sweetest thing is sugar?

LATIF: Which feels like an extremely anticlimactic answer, right?

LULU: It's just—I mean, we're just back where we started.

LATIF: We are. We are back where we started but, like, for a kind of profound reason, actually.

LINDA BARTOSHUK: Sugar plays a critical role in survival. Glucose is the best fuel the brain can use.

LATIF: From the very beginning, Linda says ...

LINDA BARTOSHUK: The first thing when a baby is born, you want the baby to do is nurse. And the baby has reflexes that help it begin to nurse, but the sweet taste of mother's milk ...

LATIF: The sugar in the mother's milk.

LINDA BARTOSHUK: ... is what keeps it nursing. So sweet taste is an incredibly important cue.

LATIF: Our brains basically evolved this particular sensation—the reward of sweetness—as a way to get us to want sugar.

ERIC WALTERS: Yeah. The receptors have evolved specifically to respond to sugar.

LATIF: Like, it's the thing the light switch was made for.

LINDA BARTOSHUK: In fact, there have been theorists in the past who've thought that sweet might be the beginning of our understanding of pleasure.

LULU: Ooh, that's interesting!

LATIF: And so I started to see sugar and sweetness as almost the same thing. Like, sweetness doesn't describe sugar, it—it is sugar.

LULU: Yeah.

LATIF: Which is cool, and which is revelatory of our basic human nature. But also, like, I don't know, I still was craving more. Like, there's a limit here. I just want to go beyond it. And lucky for me, I ended up stumbling into a whole world of things that could take us beyond that limit.

LULU: Really?

LATIF: And I'm gonna take you into uncharted sweetness territory. And that's after the break.

LULU: This is Radiolab. I'm Lulu. I'm here with Latif Nasser.

LATIF: Yeah.

LULU: Latif is on a quest to discover the sweetest thing in the world, on the planet, the sweetest thing on Earth. And where we left off, you were at a potential answer that the sweetest thing is sugar.

LATIF: Yeah—except maybe not. Okay, so Lulu, what is sweeter: a strawberry or blueberry?

LULU: I think a strawberry.

LATIF: So a blueberry has technically more sugar.

LULU: Really?

LINDA BARTOSHUK: That's right. The blueberry has twice as much sugar in it.

LATIF: According to Linda Bartoshuk ...

LINDA BARTOSHUK: There are fruit that can make their sugar sweeter.

LULU: What?

LINDA BARTOSHUK: Now why do fruits care? Because animals that eat the fruits spread their seeds. So the fruit would really like that sugar to be sweeter, and maybe the fruit doesn't know how to add more sugar to it. I'm not talking about the fruit's got consciousness. Of course it doesn't. Evolution is doing this.

LATIF: Right.

LINDA BARTOSHUK: But what has happened through evolution is that some fruit are now using volatiles, which makes the smell of the fruit ...

LATIF: Mm-hmm.

LINDA BARTOSHUK: ... to increase the sweetness.

LATIF: Volatiles are just little molecules that float around in the air. They make things smell.

LULU: Huh.

LINDA BARTOSHUK: Now there are two ways you can perceive volatiles.

LATIF: Uh-huh?

LINDA BARTOSHUK: You probably only know about one of them, and that's you sniff them.

LATIF: Right.

LINDA BARTOSHUK: But what happens when you put food in your mouth that is giving off odors?

LATIF: Hmm.

LINDA BARTOSHUK: You chew it. You're releasing the odors in your mouth. And when you swallow, those odors are pumped through a hole in the back, and they go into your nose.

LATIF: Uh-huh.

LINDA BARTOSHUK: And can intensify the sweet signal in the brain.

LATIF: So the strawberry tastes sweeter than the blueberry because it puts out all of these non-sugar smell molecules that send smell signals to your brain, which overlap with the taste signals and give them a little boost.

LULU: Huh!

LULU: And according to Paul Breslin ...

LINDA BARTOSHUK: So as an ape, our species, our natural proclivity is to mostly want to eat fruit.

LATIF: Thanks to our long evolutionary history with fruit ...

PAUL BRESLIN: A lot of animals can make their own vitamin C. Humans can't make their own vitamin C, so we have to eat fruit.

LATIF: Even if something just looks kind of fruity or reminds you of a fruit, it's like there's just an extra little bell ringing in our heads.

PAUL BRESLIN: So if you play with vision, if you make something very fruity that you associate with sweetness, you can perceive it as being more sweet.

LATIF: Huh.

PAUL BRESLIN: Or if you color it red so it looks like a nice ripe fruit, that can actually make the sweetness perception go up.

LULU: No! So if you were to take the same packet of sugar and dye some of it red, the red would taste sweeter to me?

LATIF: That's right.

LULU: That's hard to believe.

LATIF: Well, did you bring the stuff I told you to bring?

LULU: Yep.

LATIF: Okay. You have some honey.

LULU: I have some honey.

LATIF: Okay. Why don't we first get our sort of baseline? Take a tiny bite.

LULU: Just normal old honey. Here we go.

LATIF: Yeah.

LULU: Okay. Very sweet.

LATIF: Okay. So number two, I want you to take that honey.

LULU: Okay.

LATIF: Grab some strawberry extract and red food coloring.

LULU: Okay.

LATIF: Mix that all up.

LULU: Eww! It looks like—almost like cherry cough syrup.

LATIF: Okay, so keep that normal honey we just had in mind. Now taste the strawberry honey, and tell me if it's sweeter.

LULU: And I should, like, look, I guess. Oh, significantly!

LATIF: Right?

LULU: Significantly! Yeah. Wow!

LATIF: It's kind of dramatic, right?

LULU: Yeah. It's interesting. It's not sweeter in, like, what I was expecting, like a syrupy sweeter way.

LATIF: Yeah.

LULU: It's almost like I picture all these, like, flowers. Like, it's like flowery sweeter.

LATIF: Okay, now ...

LULU: There's another thing?

LATIF: Yeah. I mean, by this point I was obsessed with ways to jack up the perception of sweetness, and I found all these studies that suggest that along with smell and vision, sound actually works for sweet as well.

LULU: What?

LATIF: So there are certain high-pitched tones that you can play and you can enhance sweetness by as much as five to ten percent.

LULU: Wait, why would that be? What's the evolutionary—what's the why?

LATIF: Such a good question. I looked it up, and no one knows for sure.

LULU: Okay, fair. [laughs]

LATIF: It is a mystery.

LULU: Okay.

LATIF: But they have seen it happen over and over in experiments. Okay. So, like, I'm about to play you a song. This was used in a study at the Science Museum of London. Here, let's just see if it works for you.

LULU: Okay.

LATIF: Okay, you ready?

LULU: I'm ready.

LATIF: Okay, here it is.

[music plays]

LULU: This is like the music you see in, like, 1950s animations of candy dancing.

LATIF: Okay, eat the red honey again.

LULU: Okay. Wow. It gives it, like, more dimension. It's sparklier. Crystal-y.

LATIF: When you talk about the crystals, is it because your honey is, like, kind of hard?

LULU: My honey's a little old. [laughs]

LATIF: So maybe the crystal-y quality is because of the old honey, really, instead of the music?

LULU: Uh-huh.

LATIF: Okay, but I do agree. I think there was a step up.

LULU: The strawberry step up was pretty dramatic.

LATIF: And I feel like the sound step was maybe harder to tell.

LULU: Yeah, a little subtler.

LATIF: So at this point, I was like, okay, cool. These hacks definitely work. But also, they're not so dissimilar, like the flavor and the color, it's not so dissimilar to what candy companies are already doing. Like, it just felt like I was like, oh, I feel like I'm back to gummy bears here.

LULU: Right.

LATIF: And then I was like, how can we get even sweeter than this?

LULU: Uh-huh?

LATIF: So then I thought, what if we just went to the source of all of this?

CHARLES ZUCKER: Remember, you know, taste ultimately is in your brain.

LATIF: Which took me to the lab ...

LATIF: Okay, here we are. We're at Columbia University, with all these, like, brain scans on the wall here.

LATIF: ... of this geneticist and neurobiologist, Dr. Charles Zuker.

CHARLES ZUCKER: I'll shake the microphone.

LATIF: He was one of the people, along with other scientists like Danielle Reed, who discovered the sweetness receptor.

LULU: Oh!

CHARLES ZUCKER: And I've dedicated my career to study how detection gets transformed into perception.

LATIF: And since then, he's been following that sweet signal from the taste receptor into the brain.

CHARLES ZUCKER: So it goes from the tongue to ganglia, from ganglia to brainstem, to brainstem to a different station in the brain stem, where it gets further processed. From there, it goes to the thalamus. And the thalamus goes to the cortex.

LATIF: Somewhere along the way here, we know that sight and smell can join up and boost the signal. But regardless, the cortex ...

CHARLES ZUCKER: Is where you now say, "Ah, this is sweet."

LULU: Huh.

CHARLES ZUCKER: I was saying, you know, the typical laboratory, you know, you have benches and you have desks.

LATIF: So we actually visited Charles's lab ...

CHARLES ZUCKER: And then we have lots of specialty rooms.

LATIF: ... where he studies this pathway to see, okay, what happens if we move this over here? What happens—what happens if we block it over here?

LULU: Or if we block the train here or something?

CHARLES ZUCKER: So normally the cells have the sweet receptor.

LATIF: Mm-hmm.

CHARLES ZUCKER: And that's why sweet activates that pathway all the way to the brain.

LATIF: Yeah.

CHARLES ZUCKER: But if instead there I put, let's say, a bitter receptor ...

LATIF: Mm-hmm?

CHARLES ZUCKER: ... now the bitter chemical will activate the same sweet pathway.

LATIF: Right.

LULU: Whoa!

LATIF: To be clear, he is not doing all of this for the reasons that we are, to try to find the sweetest thing or the sweetest sensation. He is working to understand really how sweetness and taste work in the brain. And who knows, maybe that knowledge could help us deal with issues like addiction, obesity, eating disorders, diabetes.

LULU: Mmm, okay. Yeah, sure.

LATIF: So one of the things he's doing is he takes some mice, and he zeroes in on their sweet taste sensation neurons.

CHARLES ZUCKER: We introduce into only those neurons a little light switch.

LATIF: Meaning they genetically engineer these neurons and add a genetic sensitivity to light.

CHARLES ZUCKER: And then we put a fiber optic in their head.

LATIF: Ah!

CHARLES ZUCKER: And then we turn the laser on.

LATIF: Which triggers the neuron.

CHARLES ZUCKER: And the brain will say, "Ah, sweet."

LATIF: Yeah.

LULU: Oh my gosh. Oh, my gosh. So, and by—by beaming in light, it just—whatever it's tasting will taste sweet?

LATIF: Yeah, even if it's not tasting anything.

LULU: What?

LATIF: I mean—why are we then even bothering with candy? Why don't we just do that to ourselves?

CHARLES ZUCKER: Very good. Excellent. Come on. People go around with pacemakers.

LATIF: Yeah, sure.

CHARLES ZUCKER: And—and I could see a future where that could be done.

LATIF: Which I mean, in terms of lifestyle, like that could be—just imagine, like, that could be revolutionary. Think about, like, you could get the perfect sugar hit, no calories, no insulin spike. You could even pair it with whatever you want, which means, like, your kids could be eating spinach and it tastes like candy, right? And ...

LULU: Yeah. Okay that's—that's kind of neat. [laughs]

LATIF: Yeah, but because we're on this mission here for the sweetest thing, I was like, wait a second but could you use that same thing? Could you use that same laser light and crank it up to the highest it can go, and just blast that sweetener on and get something that is the sweetest thing that anyone has ever tasted? Like, you could maybe get a sweetness that we have never known. A sweetness that has just been totally blocked off from us, just from the physical reality of sugar. So I asked him. And Charles was like ...

CHARLES ZUCKER: In principle, I could imagine yes.

LATIF: You could potentially create the sweetest sweet. You could transcend. The sweetest thing could be light. Like, it could be nothing.

LULU: I don't like it.

LATIF: You don't like it.

LULU: I don't like it.

LATIF: Why not?

LULU: I don't know. It's like, let's divorce ourselves from the real world even more, so that pleasure itself doesn't even have to be found—your boys ask this question about what is there to find in the world? This just says you can get it from the inside. And aren't we siloed enough?

LATIF: Yeah. I mean, kind of. But, like, really, it's—I feel like my takeaway from all this reporting is like, it's kind of all happening in your mind anyway. It's all a mind game.

LULU: Hmm.

LATIF: Taste. And for me, like, talking to Charles, I was just like, whoa, we're opening up a whole new world. Like, what even is possible here? Like, what can we do? What are the places we could go?

LULU: Yeah, but it's like—the whole new world is just on your couch. Like, at least with a search, you have to get out the door and be surprised. Like, if somebody uses this, what incentive do they have to leave—to leave the house?

LATIF: Yeah. I mean, sure, but if you could definitively know that this experience will be sweeter than anything you could ever experience out in the world, wouldn't you try that?

LULU: Maybe.

LATIF: Okay, okay.

LULU: I'm just not sure I'd like it.

LATIF: Okay, I get your—I get your hankering for wanting to go someplace new. Let me take you one last place that this mapping of sweetness took me that I did not expect.

LULU: Okay.

LATIF: So last month, a team of researchers at the Center for Astrobiology in Spain ...

LULU: Mm-hmm?

LATIF: ... were looking at a cloud of interstellar dust and gas near the center of the Milky Way. You know, spectroscopy, you know about that?

LULU: I think it's like you detect based on the light waves being emitted, you get clues on what the substance is?

LATIF: That's right.

LULU: So cool.

LATIF: So they did this on this kind of cloud of interstellar dust.

LULU: Okay.

LATIF: And what they found in that cloud was a huge amount of a molecule called erythrulose.

LULU: Erythrulose. Okay.

LATIF: It's a four-carbon sugar.

LULU: Oh!

LATIF: This is the first time ever they found a—not only a sugar, a relatively complex sugar in deep space.

LULU: What—and would it taste like sugar to us?

LATIF: So the crazy thing ...

LULU: Yes?

LATIF: ... is that this exact sugar, erythrulose ...

LULU: Yes?

LATIF: ... happens to be found ...

LULU: Yes?

LATIF: ... in raspberries.

LULU: [gasps]

LATIF: Yeah.

LULU: Wait, wait. Space tastes like raspberries?

LATIF: No, no, no, just this one cloud. But it does—it does make you wonder, right?

LULU: Uh-huh.

LATIF: Like, if this is just out there as a raw material just floating, like, maybe that is a big clue for us that there is a space raspberry somewhere.

LULU: Whoa! And—and do they now think maybe there's sugar, like, all up in Neptune and burning out of the sun?

LATIF: There has to be enough of it that you can read it on a mass spec.

LULU: The scientists have spectroscopy. They need tasteoscopy.

LATIF: The next Hubble telescope, it's just like a giant tongue that they send out.

LULU: You know, you just make a rocket with just tongues. Just "Ahh!"

LATIF: The James Webb tongue, yeah.

LULU: The James Webb tongue. Yeah. And then, you know, you added microgravity. Is that gonna work like sonic seasoning?

LULU: Latif Nasser, who himself scores pretty high on my list of the sweetest things on this planet.

LATIF: If only my kids liked me as much as they like gummy bears.

LULU: [laughs]

LATIF: Thank you to you, Lulu. Thanks to my kids. Thank you to Jialin Deng who composed the song that was our sonic seasoning. Thank you to Laura Rickman and everyone else at Columbia University's Mortimer B. Zuckerman Mind Brain Behavior Institute for hosting us. And a major thank you to Grant DuBois, to Charles Spence at Oxford University and to Danielle Reed at the Monell Chemical Senses Center. They were all extremely helpful in explaining their work and taste in general to us. We're very grateful for their help.

LULU: This episode was reported by Latif Nasser with help from Jessica Yung.

LATIF: It was produced by Jessica Yung, with help from Mona Madgavkar, Maria Paz Gutiérrez, Gabby Santas, and Maia Appleby Melamed.

LULU: It was edited by Pat Walters, fact-checking by Sophie Samiee. This is Radiolab. I'm Lulu Miller.

LATIF: And I'm Latif Nasser. Stay sweet, everybody.

LULU: Bye!

LULU: This is Lulu here from a couple weeks after we recorded this episode with a note that I'm passing along from Latif. He's not reading it himself—you'll see why. Here we go. Okay, so "Hey, folks. Latif here. Before we leave you, I just wanted to let you know—possibly TMI—that I injured my vocal cords. It's nature's way of telling me I talk too much, and I'm under doctor's orders to talk as little as possible for the couple of months. So I'm off on medical leave—putting a sock in it, so to speak. I'll be leaving you and your ears and brains in the capable hands of the rest of the Radiolab team. We have fascinating episodes coming up from Matt and Molly and Annie, Avir, and of course, Lulu—"nyah, thanks! "—about everything from grass to sulphur to—well, dust. I'll be back before you know it. Take care of your throat!"

LULU: Latif, take care of your throat—tea, rest, no talking. We love you, Latif. And again, don't worry, friends. We have so many goodies coming up, some of which Latif was already in, so you'll probably be hearing him anyway. And he will be back in a couple months. Thanks for listening!

[LISTENER: Hi, I'm Ethan, and I'm from Brooklyn, New York, and here are the staff credits. Radiolab is hosted by Lulu Miller and Latif Nasser. Soren Wheeler is our executive editor. Sarah Sandbach is our executive director. Our managing editor is Pat Walters. Dylan Keefe is our director of sound design. Our staff includes: Jeremy Bloom, W. Harry Fortuna, David Gebel, Maria Paz Gutiérrez, Sindhu Gnanasambandan, Matt Kielty, Mona Madgavkar, Annie McEwen, Alex Neason, Sarah Qari, Natalia Ramirez, Joanna Strogatz, Anisa Vietze, Arianne Wack, Molly Webster and Jessica Yung, with help from Gabby Santas and Maia Appleby Melamed. Our fact-checkers are Nora Belblidia, Hilary Elkins, Rachel Gross, Diane Kelly, Emily Krieger, Natalie Middleton and Sophie Samiee.]

[LISTENER: Leadership support for Radiolab's science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.]

 

-30-

 

Copyright © 2026 New York Public Radio. All rights reserved. Visit our website terms of use at www.wnyc.org for further information.

 

 New York Public Radio transcripts are created on a rush deadline, often by contractors. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of programming is the audio record.