JAD ABUMRAD: Next up, producer Molly Webster and carbon.

MOLLY WEBSTER: All right.

JAD: Okay, you just want to launch in?

MOLLY: Yeah. So science and ...

ROBERT KRULWICH: Yay!

MOLLY: Yeah. This is my new thing with my sisters. I just always go, "#Science," because they get really sick of me trying to teach the kids science-y lessons. "Just #Science it." Okay, so one of the biggest mysteries in biology is how old am I?

JAD: That—that doesn't seem like a mystery.

MOLLY: Well, I mean, like, obviously I'm Molly Webster who's 32 years old, who has lived, you know, through 32 birthdays, I guess.

JAD: Yeah.

MOLLY: But this is a question of, like, we know that some cells in our body regenerate, and so it's like, how old are those cells? Like, how old is my heart right now?

ROBERT: Hmm.

MOLLY: Or how old is my eyeball, or how old is my nose?

JAD: Spleen.

MOLLY: The northwest corner of my kidney.

ROBERT: Is this like, if I'm three years old and now I'm 33 years old, do the cells in the 33-year old—are they the same as—are any of them the same as the one when I was three? Is that the question?

MOLLY: Yeah, that's one of the questions. Are any of them the same? If they're not the same then how often do they change?

ROBERT: Hmm.

MOLLY: Because if you understand that then you might be able to, like, solve injuries, help people heal faster, or fix diseases where cells are, you know, messed up like psoriasis or anemia or ALS, or something like that. But also, it just seems so cool to be able to be like, "Oh, that chunk of my heart is from 1997."

ROBERT: Yes.

JAD: That's super cool.

MOLLY: Or, like, that other chunk of my heart is from 1983.

JAD: Yes.

ROBERT: Oh, I would love to know that. At the party of Robert, I would want to meet the original Robert cell. So if there's anybody who's been here since 1947 I'd love to just say hello, and if you just joined me in 2015, well that's nice.

MOLLY: Right. It would be super cool.

ROBERT: Yeah.

MOLLY: So one of the questions they've had for a long time is, "Is there a way that we can try to date cells?" And so they're like, "Well, we can't really send anything into the body because that can be toxic." So the answer for a long time had been no. And then, 2002-ish, this little idea pops up, and it's something called the bomb pulse.

ROBERT: B-O-M-B? Bomb?

MOLLY: B-O-M-B, and then pulse, P-U-L-S-E.

JAD: Bomb pulse?

MOLLY: Yeah. To explain ...

[ARCHIVE CLIP: Five, four, three, two, one. There it goes.]

MOLLY: In the 1940s and '50s, we all know this, we ...

[ARCHIVE CLIP: Christmas color, there is the ground wave. It is over folks.]

MOLLY: We tested a lot of atomic bombs.

[ARCHIVE CLIP: It worked! It worked! There's a huge fireball.]

MOLLY: The first test was in 1945. Trinity test, New Mexico. A few weeks later ...

[ARCHIVE CLIP, Harry Truman: The world will note that the first atomic bomb was dropped on Hiroshima.]

MOLLY: Hiroshima, and Nagasaki.

[ARCHIVE CLIP, Harry Truman: We shall continue to use it ...]

MOLLY: So then as World War II comes to an end, the rest of the world just tries to catch up to the US.

[NEWS CLIP: The Reds are to explode a huge bomb of 50 megatons.]

MOLLY: The Russians. Then after the Russians ...

[NEWS CLIP: Britain fires its first H-bomb.]

MOLLY: ... the British, the French. The whole Cold War basically just continues to unspool. All in all, over 400 atomic tests went off above ground between 1945 and 1963.

[ARCHIVE CLIP: Just imagine: if only one atom bomb were to be dropped on an American city, thousands of persons would be killed instantly.]

JAD: That was a sucky time.

MOLLY: Well, #Science.

ROBERT: [laughs]

MOLLY: Here's one good thing. Potentially one good thing popped out, and that is an answer to the question of how old are we?

JAD: That somehow came out of the bomb tests?

MOLLY: Yeah.

JAD: How?

MOLLY: Let me explain.

JAD: Do it.

MOLLY: So with every one of those detonations, when an atomic bomb goes off it would shoot a whole bunch of stuff up into the atmosphere, all of these, like, radioactive elements like cesium and plutonium and all these things. But also, that explosion shoots up a bunch of neutrons and the neutron will crash into the nitrogen that's floating in our atmosphere and create C-14, which is a very special type of carbon. It has two extra particles in it. Now as all that bad radioactive stuff starts falling out of the atmosphere back to the ground, C-14 doesn't fall out of the sky. It just sort of floats there. And what happened is over time the wind currents carried C-14 from these test sites and just spread it all over the planet. And this C-14, which is just totally like normal carbon, not harmful, it just bonds with oxygen and it gets sucked up into plants. And then animals eat the plants, and then we eat the animals, or we eat the plants, and then suddenly the C-14 is in us.

JAD: Hmm.

MOLLY: So we all have a little bit of the atomic age in us.

JAD: Wait, but I wasn't even born in 1963, so why would it be in me?

MOLLY: That is the cool thing, because it hangs out in the air for a long time. So it's actually still up there.

JAD: Hmm.

ROBERT: But why does this have anything to do with dating anything?

MOLLY: Yeah, so I'm about to tell you that.

MOLLY: Hey, you there?

BRUCE BUCHHOLZ: Hi, yes I am.

JONAS FRISÉN: Yeah, yeah.

MOLLY: Perfect.

BRUCE BUCHHOLZ: I'm Bruce Buchholz. I am a senior scientist at Lawrence Livermore National Lab.

JONAS FRISÉN: Jonas Frisén, professor of stem cell research at the Karolinska Institutet in Stockholm.

MOLLY: So in the early 2000s, Jonas is staring down this question of, like, how do I date cells, and at a certain point he gets together with Bruce because he comes up with this idea which is just, "Oh, maybe we just look up."

BRUCE BUCHHOLZ: So there are some groups in Europe. There's one in particular that's been measuring the atmosphere every two weeks since the late 1950s.

MOLLY: Oh my gosh!

BRUCE BUCHHOLZ: Which is—it's an incredible data record.

MOLLY: Bruce says what these scientists have done is they've taken all of these measurements and they put them into one chart, so you can see the amount of C-14 in the atmosphere over time.

BRUCE BUCHHOLZ: So we have this, basically a—basically a calendar. I could send you a picture so you can see what the graph looks like.

MOLLY: Yeah, I'd love to see a picture.

MOLLY: What you see on that graph is this, according to Jonas ...

JONAS FRISÉN: Up to 1955, it's a pretty flat line, with very little variation, but then suddenly in 1955 ...

MOLLY: With all the bomb tests ...

JONAS FRISÉN: ... there's a very sharp increase.

BRUCE BUCHHOLZ: A lot of carbon-14, very dramatic increase. That's why they called it a pulse.

MOLLY: And that increase goes all the way up to 1963 when ...

[NEWS CLIP: The Kremlin, fortress of communist doctrine, is the setting of an historic event.]

MOLLY: ... when the US, the UK and the Soviet Union agree to stop exploding atomic bombs above ground.

[NEWS CLIP: The signing of an atom test ban.]

JONAS FRISÉN: After that, there's a gradual decline.

MOLLY: And, you know, they're just measuring it all the way down so they can just say, "Oh, like, here's where it was in 1980, here's where it was in 1990, 2000, 2010." This right here is the coolest part, because the amount of C-14 in the atmosphere at any given moment is directly reflected in our cells, right? So if there's, like, that much C-14 in the atmosphere in September 1972, then that is going to be mirrored in cells that were born in September of 1972. So it is like this totally perfect birthday calendar.

BRUCE BUCHHOLZ: We can see approximately how long. Have they been there for 10 years, or 20 years, or 30 years?

MOLLY: It's like once this idea got out, scientists all over the world were like ...

BRUCE BUCHHOLZ: Oh yeah!

[ARCHIVE CLIP, "Tic, Tic, Tic" - Doris Day: [singing] Oh give me your attention, there’s been a new invention.]

BRUCE BUCHHOLZ: It didn't take long to see that this might be something cool to do.

[ARCHIVE CLIP, "Tic, Tic, Tic" - Doris Day: [singing] It came about because they made a big atomic bomb.]

MOLLY: So just to give you a quick sense of some of the work that came out of this, I spoke to one scientist.

KIRSTY SPALDING: I'm Kirsty Spalding, and I work at the Karolinska Institutet in Stockholm.

MOLLY: She was working with Jonas, and they figured out how to use C-14 in brains.

KIRSTY SPALDING: I mean, first of all, the basic question was, can adult humans make new neurons?

MOLLY: She says that for like 100 years ...

KIRSTY SPALDING: The dogma had always been that the neurons we're born with are the ones we die with.

MOLLY: The problem was she had no way to investigate this. She couldn't use it in humans—even if they were dead humans—until she figured out a technique where she could, like, extract brain cells and see how much C-14 was in there.

KIRSTY SPALDING: Yeah, exactly.

MOLLY: And it turns out the next best thing to a human is a horse.

KIRSTY SPALDING: Because horses can live for quite some years.

MOLLY: Decades.

KIRSTY SPALDING: So every second Tuesday I would go out to the local abattoir ...

MOLLY: The local slaughterhouse.

KIRSTY SPALDING: ... an hour away. I mean, I was a vegetarian surrounded by carcasses, and they would bring the horse's head out to me, and I had to figure out how to get the brain out of its head.

MOLLY: Wait, what? So you actually had to, like, cut open the skull and get to the brain yourself?

KIRSTY SPALDING: I mean, the second time I went I took my boyfriend with me, because I was like, "I can't do this, physically." They actually had a circular saw and I actually discovered that the skull—the bone across the top—the nose of the horses is quite thin. So that was a much easier access point. This is a really gross discussion. [laughs]

MOLLY: Did you ever see your research going that way?

KIRSTY SPALDING: No, absolutely not. Not at all.

MOLLY: But what she saw when she finally moved her research from horse heads to humans was turnover.

KIRSTY SPALDING: We found quite robust levels of new neurons in adulthood.

[ARCHIVE CLIP, "Tic, Tic, Tic" - Doris Day: [singing] I tic, tic, tic. Why do I tic, tic?]

MOLLY: Once Jonas's team showed that this worked, scientists got excited, and people started to date things, and not just cells. So can I tell you the ages?

ROBERT: Sure.

MOLLY: Okay. The baseline ages we knew before C-14 was that skin was like 14 days old.

ROBERT: 14? Oh that's only 14 days old?

MOLLY: 14 days. Yeah, so like two weeks.

ROBERT: Wow.

MOLLY: The surface level of your gut, like the skin on your gut I guess, was five days.

ROBERT: Five days?

MOLLY: So that's even shorter than skin. That's like the surface of the ...

ROBERT: Wow, so ...

MOLLY: ... intestine.

ROBERT: Oh the surface of the intestine?

MOLLY: Yeah.

ROBERT: The lining?

MOLLY: The lining that's like ...

ROBERT: Well that's—because that's everything scraping—all that food going down. So no, that doesn't surprise me.

MOLLY: And then with C-14, the deeper muscle-y part of the intestine, the average is 15.1 years.

ROBERT: 15.1 years. Oh, big difference between skin ...

MOLLY: Wait, 15.9—15.9 years old.

ROBERT: Okay, 15.9 years, hmm.

MOLLY: Fat cells was another one that they did: 10 years old.

ROBERT: 10 years old.

MOLLY: Yeah.

ROBERT: Interesting.

JAD: Why would a fat cell need to last that long?

MOLLY: 10 years?

JAD: Jesus.

ROBERT: Because it's perverse.

MOLLY: Just to torture you.

ROBERT: Because fat cells—yes!

JAD: Why would it last that long?

ROBERT: Because fat cells are mean cells.

JAD: But honestly, do they have any idea?

MOLLY: They don't know.

JAD: Huh. Do they know what would be one of the oldest part of us?

MOLLY: Your cortex, which is, like, the part of your brain that does abstract thinking, or your voluntary movements. That's as old as you are.

ROBERT: Really? Huh.

MOLLY: So if you want to know one of the oldest parts of you, the oldest cell is probably in your ...

ROBERT: Super-thinky part of your brain.

MOLLY: It'll be, like, your cortical neuron.

ROBERT: Well that fits if I think of myself as the stories I tell myself. Like, when you get Alzheimer's and you lose your stories, you lose your mind, like people say.

MOLLY: But the interesting thing, though, is the hippocampus is where you keep all your memories, and they saw that your hippocampus does make a bunch of new neurons.

JONAS FRISÉN: Yeah, so in the hippocampus ...

MOLLY: That's Jonas Frisén again.

JONAS FRISÉN: ... an adult gets approximately 1,400 new hippocampal neurons per day.

ROBERT: Really?

MOLLY: Yeah, and then each of those neurons will live, like, 20, maybe 30, years.

JAD: So does that mean that the part of Robert's brain where he keeps the stories he tells himself, that part is being made new every 20 or 30 years?

MOLLY: Yeah.

JAD: That's a strange thing that, like, your oldest stories could be stored in baby little neurons.

ROBERT: That is weird.

JAD: Yeah.

ROBERT: I remember going to Kyoto, and it's, like, the oldest most beautiful temple in Kyoto, it has exactly the form that it had hundreds of years ago. But when you walk in, the walls and the floors and the roofing, they've been restored. They've been restored actually over and over again, because in Japan what they call old is the form, it's the shape of the building. You go to Athens though, and you go up to the Acropolis and you stand in the Parthenon, there you're standing in the very temple that Pericles stood in. It's the same place exactly, same materials. So, like, in Greece they believe that the original stuff is what you preserve, and in Japan they don't. They think it's just the form. And I was thinking of this thing you're doing is sort of a little bit like that. I was thinking I'm much more Greek than I am Japanese, because I want to know what my original cells are, where they are in me.

MOLLY: Yeah.

JAD: But my question is actually more basic. It's like, why does part of me get to be reborn and the other parts of me don't? Like why not all of me get to be reborn?

MOLLY: Because if all of you is being reborn you would just crumble into dust.

JAD: No, but I mean, why does only certain parts get to regenerate?

MOLLY: It's interesting because they don't know. They said the next—they said basically this question of how old is a cell, they said no one was asking. Everyone wondered this, but no one was asking this question because they never had the tools to ask it. So now they're just starting to ask those questions, but there's a problem. This bomb pulse that we've been dependent on in the last decade to start answering all these questions is going away.

JAD: Really?

MOLLY: Every day a little more of that C-14 gets sucked out of the air.

ROBERT: So how much time do we have left before ...

MOLLY: 15 years. It's gone by 2030, give or take.

KIRSTY SPALDING: Yeah, so we need to get questions answered now because we really are working against the clock for many things we want to look at.

MOLLY: I talked to this Alzheimer's researcher who is trying to figure out, like, the chronology of the disease, like when certain pathologies form in the brain. He was kind of just like, "I just wish I had a little more time." And when I think about this—like, I was thinking about this on the subway this morning. Like, I was looking around and I was thinking—you know I'm on the L-train, it's a bunch of, like, 30-year old kids or something. And I was like, these—they're all reading or something and drinking their expensive lattes. I'm like, "These people are so far away from thinking about the Cold War or atomic bombs or anything like that, and they're all walking around with, like, this secret signal from the atomic period inside of them." And then that little signal is, like, binging out knowledge about their shoulder and their elbow and their liver, and the west side of the liver, and the east side of their liver, and like different parts of their heart, and the fact that it's now going away, and how, like, someone born in 2042 is just going to be really boring, and there's going to be no—they're not gonna have any insights into who they are.

ROBERT: Yeah, but ...

MOLLY: It sort of makes me inclined to very peacefully want to explode another atomic bomb.

ROBERT: What? No. No, no, and no.

MOLLY: Why?

ROBERT: You forget all of the poisons that it—that is not a benign event that's sort of an experimental picker-upper. That is extra—extra stuff in the air.

MOLLY: Don't kill my dream, Robert.

ROBERT: I have to kill your dream because it's a dumb, dumb dream.

[ARCHIVE CLIP, "The Atomic Telephone" - Spirit of Memphis Quartet: [singing] Lord, give us a brand new power Lord, to use for the good of all mankind. Some people going to use it to destroy everything. God didn’t mean it like that. He wants us to use it for the good of all mankind. God has talked to Jesus on the atomic telephone. Oh well, then no man knows its power. Only God alone. Oh well then, it can't cure the sick or destroy the evil. With one sweep of power, known by God alone.]

JAD: Producer Molly Webster.

ROBERT: And special thanks to Henrik Druid and Mark Lovell.

SAM BRESLIN WRIGHT: Happy Valentine's Day, magnesium. I'd go blind watching you burn, magnesium. Iodine is cute, the way it sublimates. And yes, I'll put lithium in water to watch it scoot about but my heart belongs to you, magnesium. The hot, white flame, the abandoned, the slowness of you becoming your own fuse. Mercury is beautiful, yes, but it's you magnesium. The way you burn for me, the way you leave nothing of yourself behind.

JONIECE ABBOTT-PRATT: We are flying over Greenland. Your elbow is too close to mine on the airplane armrest. Down there they are excavating uranium from beneath the Arctic ice and selling indiscriminately. Though from here I can only see the white of ice sheets and glacier-topped mountains. This is an island of fishing rigs and colorful houses, cod and catfish stew, and tomato cream. Once, I thought every isotope in me is radioactive. I make the people who love me sick. This is a teenage way of thinking, but you have uncovered a glowing spark in the pristine, frozen places within me.

JAD: That was "Uranium" from poet Emily Hockaday, read by Joniece Abbott-Pratt, and before that "Happy Valentine's Day, Magnesium" by Jason Schneiderman performed by Sam Breslin Wright.

ROBERT: Everybody has a middle name in this thing.

JAD: Yeah they do.

ROBERT: Sam Breslin Wright. Yeah, okay.

JAD: Coming up ...

ROBERT: We're gonna get into an elevator, push the button, and go down. I mean all the way down. I'm Robert Louis Krulwich.

JAD: Jad Nicholas Abumrad.

ROBERT: Yeah.

JAD: We'll continue in a moment.

[LISTENER: Hi, this is Pilar Castro from Bogota, Colombia. 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. Muchos gracias, Radiolab.]

 

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