JAD ABUMRAD: And go. Hey, I'm Jad Abumrad.

ROBERT KRULWICH: I'm Robert Krulwich.

JAD: This is Radiolab. And today ...

ROBERT: It's inheritance today.

JAD: Yeah, we're exploring questions of, like, what can you pass down to your kids and their kids?

ROBERT: Yeah.

JAD: What can't you? How much of you will echo into the future, and how much of you won't? And I've gotta say I'm feeling pretty good about this show so far.

ROBERT: Because?

JAD: Well, if a mother—a rat mother licking her baby can have such a profound effect, basically change the expression of the genes in the baby, well that's hopeful.

ROBERT: So you think you can get deep down?

JAD: Look, in the end what do I know? But I take it that we have more control over our destinies and our kids' destinies than we would've thought.

ROBERT: Well, let's not get too excited too fast, because we have a story to tell. And this one—this tale leaves me a little queasy.

OLOV BYGREN: Oh, there was a contact.

JAD: Hello, hello?

OLOV BYGREN: Yes. It's me, Olov.

JAD: This is Olov.

OLOV BYGREN: Hi, Olov Bygren. I'm in public health.

JAD: He works at the Karolinska Institute in Sweden, where he studies population data.

OLOV BYGREN: Looking for patterns in cardiovascular diseases, high blood pressure and such.

ROBERT: But the story he told us begins around 25 years ago.

SAM KEAN: Way up in northern Sweden.

ROBERT: That's Sam Kean again. He's the guy who told us about Olov's work.

SAM KEAN: In a little community called Överkalix.

ROBERT: What does it look like? Like, is it a big town? A little village?

OLOV BYGREN: It's a small forest area. Very beautiful.

SAM KEAN: But this was a really, really tough place to grow up.

ROBERT: Very isolated and very ...

OLOV BYGREN: Cold.

ROBERT: Are you near the Arctic Circle, or ...

OLOV BYGREN: North of it.

ROBERT: North of the Arctic Circle?

OLOV BYGREN: Yeah.

ROBERT: Oh!

JAD: Oh!

OLOV BYGREN: My home village was 10 miles north of the polar circle. [laughs]

JAD: Oh, so you grew up in Överkalix?

OLOV BYGREN: Yeah, yeah. We had an expression here, "Dig where you stand." [laughs]

ROBERT: And it just so happens this town is a perfect place to dig.

PEJK MALINOVSKI: Okay, I'm here. Riksarkivet, the kingdom archive.

ROBERT: Because there is more data, more information about the people of Överkalix, going farther back into the past than you can find almost anywhere else on Earth.

OLOV BYGREN: Yeah, we are really data rich.

PEJK MALINOVSKI: This is the Överkalix church parish record.

KARIN BORGKVIST LJUNG: Yes, it is.

JAD: Because here's the thing, the churches up in Överkalix kept incredibly detailed records. We actually sent our friend Pejk Malinovski to the archives in Stockholm to check it out.

PEJK MALINOVSKI: It says "registrera." Register.

JAD: In those books you can read everything about the citizens of Överkalix, going back hundreds of years.

PEJK MALINOVSKI: What's his name?

JAD: You know, their names ...

KARIN BORGKVIST LJUNG: Jans Olaf, Hanna Kaiser, Heinrik Venvei.

JAD: What year they were born ...

KARIN BORGKVIST LJUNG: 1814.

PEJK MALINOVSKI: 1881.

KARIN BORGKVIST LJUNG: She was born 1904, and this is...

OLOV BYGREN: Everything happening in the family ...

JAD: Is in these books.

KARIN BORGKVIST LJUNG: Nilsson, he was an idiot.

PEJK MALINOVSKI: He was an idiot. [laughs]

KARIN BORGKVIST LJUNG: Oh, sorry.

PEJK MALINOVSKI: What does that mean, he was an idiot? I guess 'retard.'

KARIN BORGKVIST LJUNG: Yes, he was retarded. [speaking Swedish]. He was miserable to look at.

PEJK MALINOVSKI: It's not very politically correct, huh?

KARIN BORGKVIST LJUNG: [laughs] No.

JAD: In any case, these books tell you when each of these folks died, how they died.

PEJK MALINOVSKI: From disease.

KARIN BORGKVIST LJUNG: Heart disease. From pneumonia.

PEJK MALINOVSKI: Accident.

KARIN BORGKVIST LJUNG: She drowned.

PEJK MALINOVSKI: Oh my God!

OLOV BYGREN: A lot of diagnoses, actually.

PEJK MALINOVSKI: Influenza.

KARIN BORGKVIST LJUNG: Cancer. Heart disease. Brain disease.

ROBERT: And interestingly, the church has also kept track of the farmers' ...

OLOV BYGREN: Crops.

PEJK MALINOVSKI: Crops and livestock.

SAM KEAN: How much they were growing each year.

ROBERT: Which turned out to be kind of an interesting thing to look at it because the people in Överkalix who were farming ...

SAM KEAN: Trying to eke a living out of the soil.

PEJK MALINOVSKI: Here we have how much they harvested.

ROBERT: They would experience these wild changes from harvest to harvest.

JAD: What you see in the records is that one year ...

PEJK MALINOVSKI: Potatoes.

JAD: ... crops that do great ...

PEJK MALINOVSKI: 100 liters. Oh, that's a lot of potatoes!

ROBERT: A few years later, there'd be a harsh winter.

OLOV BYGREN: The crops failed.

SAM KEAN: And when the crops failed ...

OLOV BYGREN: Famines.

PEJK MALINOVSKI: Yeah.

KARIN BORGKVIST LJUNG: So sad.

JAD: They'd basically starve. I mean, when you look at the records, you don't see huge spikes in mortality.

OLOV BYGREN: So they didn't starve to death.

JAD: But they suddenly had to get by on a tiny fraction of the food that they were used to.

OLOV BYGREN: They didn't have grains. I mean, they didn't have porridge.

SAM KEAN: And so they just had to hold on for the entire winter.

ROBERT: But then a few years would pass, crops would bounce back.

PEJK MALINOVSKI: And we have a lot more grain here.

KARIN BORGKVIST LJUNG: Yeah.

ROBERT: And suddenly ...

OLOV BYGREN: Plenty of food.

ROBERT: ... they could eat twice, three times as much.

JAD: But then ...

PEJK MALINOVSKI: Oh, no!

OLOV BYGREN: Total crop failure.

JAD: ... famine again. And these changes would just bounce back and forth.

ROBERT: Feast.

JAD: Famine.

ROBERT: Feast.

JAD: Famine.

ROBERT: And feast again.

JAD: And looking at these swings in fortune, Olov realized what he had here was ...

SAM KEAN: A nice, natural experiment.

JAD: Because with all this data, he and his team could follow families forward in time, through the generations.

ROBERT: So if they saw somebody who was starving as a kid in 1820, they could then see well, when those people had children and grandchildren, did anything change? Were there any consequences?

SAM KEAN: They wanted to see basically the effects of starvation on multiple generations.

JAD: What did you discover?

OLOV BYGREN: It was a very interesting discovery.

ROBERT: It's a little odd, actually. Here's what Olov says he found in the data: if you were a boy in Överkalix between the ages of nine and 12 years old—that's the window, nine to 12, you're a boy. And then we have one of those terribly rough winters and you're eating much less than normal, assuming that you can survive the ordeal, and you grow up and you have kids of your own, the data seems to say that your kids will benefit from your suffering.

OLOV BYGREN: Yeah. Yeah.

JAD: They'll do better?

SAM KEAN: If you have a starving daddy, it turns out that the baby actually gets some sort of health benefit.

JAD: Really?

OLOV BYGREN: Yeah.

SAM KEAN: And these effects, in fact, were so strong that you could trace it to the grandfather.

JAD: The grandfather? Two generations?

SAM KEAN: It seemed to have been passed down for multiple generations.

ROBERT: You mean if you had a starving grandfather, you would be a healthier boy for the—because you had a starving grandfather?

SAM KEAN: You got a health boost if you had a starving grandfather.

JAD: What sort of health boost?

OLOV BYGREN: Well ...

JAD: Olov told us, take heart disease. He said, if you were a boy, and you starved between the ages of nine and 12, and then you went on to become a father, then a grandfather, your grandkids ...

OLOV BYGREN: They were protected.

ROBERT: Meaning that they had less incidents of heart disease?

OLOV BYGREN: Much less.

ROBERT: How much less?

OLOV BYGREN: Well, it's one-fourth, can we say.

ROBERT: One-fourth?

ROBERT: Let me say this again. If you're a starving boy between nine to 12 years old—now it doesn't matter a whole lot what happens to you after this—your grandchildren will have one-quarter of the risk of heart disease then if you were eating a whole lot between nine and 12. One quarter!

JAD: Not only that, apparently those grandkids ...

SAM KEAN: Were less prone to diabetes. They lived longer lives. Something like 30 years on average.

ROBERT: 30 years?

SAM KEAN: This was a really, really big effect.

ROBERT: Instead of dying at 40, I'd live to 70? That kind of 30 years?

SAM KEAN: Yes, exactly.

OLOV BYGREN: [laughs]

ROBERT: I wonder—it's such a surprising result, I wonder how much you believe in it.

OLOV BYGREN: The results are there. It's only the mechanisms are not so clear.

ROBERT: But the results are very clear. The results are obvious to you.

OLOV BYGREN: The results are quite obvious.

JAD: Just to be sure, we asked Frances Champagne what she thinks of this data.

FRANCES CHAMPAGNE: I believe it.

ROBERT: Oh, you do?

JAD: And Michael Meaney as well.

MICHAEL MEANEY: I think the Swedish data are really, really strong and very reliable.

JAD: Everybody we talked to seems to think there's something really interesting going on here. But what exactly—maybe you can explain this to me, Robert. What exactly happens between nine to 12 that makes this big difference?

ROBERT: Well, so here's the thing: how old are your boys right now?

JAD: Three and eight months.

ROBERT: Okay. So here's what you're going to notice. Your boys will first grow taller and taller for the next few years, and when they get to be about nine, 10 years old, they're gonna stop growing just for a few years.

SAM KEAN: This is what's called the slow growth period.

ROBERT: Just for those years. That's nine, 10, 11.

OLOV BYGREN: Just before puberty.

ROBERT: They won't grow much on the outside, but on the inside ...

OLOV BYGREN: That is the time where the sperms are developing.

SAM KEAN: What's happening during this time is that you're setting aside the stock of cells that you're going to draw on in the future to make sperm cells.

OLOV BYGREN: So they are pre-sperms.

ROBERT: So the thought is when those little boys in Överkalix were really, really hungry, their hunger started a chemical process that reached all the way down to the DNA inside the boy's sperm.

OLOV BYGREN: Something happens on the molecular level.

JAD: What, exactly?

OLOV BYGREN: Well, the DNA, the RNA, micro-RNAs, histone.

JAD: Hey, wait. That—you're just renaming it.

OLOV BYGREN: Methylations, phosphorylation, and so on.

JAD: [laughs] You're just—just judo, that's all this is.

OLOV BYGREN: [chuckles]

ROBERT: Truth is, we don't know precisely how this happens, but somehow the experience of starvation marks the DNA. Maybe like those methyl things we were telling you about with the rats?

JAD: Yeah.

ROBERT: Telling some genes to turn off now, other genes to turn on. And the incredible thing is those marks stick around.

SAM KEAN: The sperm carries these marks to the next generation.

ROBERT: And then the next one after that!

SAM KEAN: Right.

ROBERT: So somehow, by some chemical mechanism, starving grandpa, back when he was about nine to 12 years old, turned out to be a good thing.

JAD: So it's like grandpa's struggle is sort of jumping forward and giving me a leg up?

ROBERT: Well, that's the good news. But unfortunately, there's—there is some bad news here.

JAD: Yeah?

ROBERT: If your grandpa didn't starve, instead he lived through great times, he stuffed himself silly, nine, 10, 11 years old, so he's a happy grandpa. You the grandson, you then would have ...

OLOV BYGREN: Higher frequencies of heart attacks. As to diabetes, it was a four-fold risk.

ROBERT: Four-fold. 400 percent greater?

OLOV BYGREN: Yeah.

JAD: I gotta say this is spooky. This is spooky because it's like ...

SAM KEAN: It does get—yeah.

JAD: I mean it's like, what if grandpa has a bad day? Suddenly you're marked.

SAM KEAN: Yeah.

ROBERT: Frankly, this makes being nine, 10, 11, 12 like a rather crucial ...

SAM KEAN: And at a time when you're not making the best decisions anyway.

JAD: Yeah, because grandpa's just nine.

SAM KEAN: I should add too, they have found very similar effects for smoking, for instance. If you start smoking when you're, you know, 10, 11, something like that, you end up having children with more problems.

JAD: I initially felt very hopeful and excited about this research, because it seems to suggest that a body, one body can respond to an environment and change and be flexible in a way we didn't think was possible. But this stuff you're telling me about Sweden feels very grim in a certain way.

ROBERT: Although, you know, sometimes your grandfather's suffering helps you.

JAD: Even if it helps, it's horrifying. It kinda makes me claustrophobic.

SAM KEAN: You feel kind of hemmed in by what your grandfather did?

JAD: A little bit.

SAM KEAN: I guess the way I would look at it is that you can change your environment a lot more easily than you can change your genes.

ROBERT: I think what's weird here is that—is that we started trying to make a difference in our children, and now we're surprise attacked by our grandparents.

JAD: [laughs] I'll tell you what I'm gonna do, though. When Emil gets to be eight, I'm cutting him off. The kid's not eating at all.

ROBERT: [laughs] "This may hurt you my son, but I'm doing it for my grandchildren."

JAD: Thanks to Olov Bygren, reporter Pejk Malinovski and ...

KARIN BORGKVIST LJUNG: Karin Borgkvist Ljung, and I'm a senior archivist at the National Archive in Marieberg in Stockholm.

[SAM KEAN: Hello, this is Sam Kean.]

[GENE KEAN: My name is Gene Kean. I'm Sam Kean's dad.]

[SAM KEAN: Radiolab is produced by WNYC.]

[GENE KEAN: And distributed by NPR.]

KARIN BORGKVIST LJUNG: Bye, bye.

[ANSWERING MACHINE: End of message.]

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