Radiolab - Infective Heredity

Episode Date: September 21, 2018

Today, a fast moving, sidestepping, gene-swapping free-for-all that would’ve made Darwin’s head spin. David Quammen tells us about a shocking way that life can evolve - infective heredity. To figure it all out we go back to the earliest versions of life, and we revisit an earlier version of Radiolab. After reckoning with a scientific icon, we find ourselves in a tangle of genes that sheds new light on peppered moths, drug-resistant bugs, and a key moment in the evolution of life when mammals went a little viral. Check out David Quammen's book The Tangled Tree: A Radical New History of Life  This episode was produced by Soren Wheeler.  Support Radiolab today at Radiolab.org/donate. 

Wait, you're listening. Okay. All right. You're listening to Radio Lab. Radio Lab. From W. N. Y. See? See?

That incredibly talented young boy was soon a talented young man, composing symphonies. Hello, hello. Hello. Robert, hi. Hi. What was that? That was the mist of classical music.

The public radio, he suddenly interrupted. by science journalist and author David Kwanman. Hey, are we all here now? Now we're all here. And you are Janet Bumrod. I'm Robert Robbins. This is Radio Lab.

And actually, what happened here is I called David because he has just published a book, which contains an idea that I found so surprising. I had not known of this. It's kind of a smack in the face to Charles Darwin's Theory of Evolution. Yes. There have been a number of accent at goo that have been added to Darwin's theory over the last 150 years or so since he published it. But this is more than that. This is a big frickin' asterisk. And to explain what that means, David told me a story about a moth. Yes, the peppered

moth. It lives in forests of central England, among other places. And during the 19th century, this moth was white with little flecks of black on it. And these moths sometimes roost on the, on the trunks of trees. And the trunks of trees surrounding Manchester, England were sort of light-colored. So when these moths roosted on the trees, they were pretty well camouflaged. A light, slightly peppered moth on a light, slightly peppered tree trunk. So they were protected against predation by birds. And then the tree trunks changed. Why did the tree trunks change? Because of the industrial revolution. Because the smokestacks of Manchester, were turning out a lot of coal smoke.

They were burning coal for all their industrial processes. And there was this soot, this coal soot that was coming out, and it was blanketing the trees in the nearby forest. So the tree trunks turned black. And the moths were no longer camouflaged because the moths were white. You wouldn't want to be a white moth sitting against a coal black tree because then your herd would know exactly where you are. Right.

What happened? The moths turned black. Oh, yeah, sure. This is the classic sort of evolution story. Exactly. That story was told, it became a textbook example of Darwinian evolutionary change in real time. And the way that happens, we were told, is that once the trees turned dark, the moths, changed by incremental mutation. Like, you know, thanks to some tiny little mistake in some moth gene, the black spacket.

The spackling got bigger on certain moths, and those were a little bit more protected, and then the spackling got a little bit bigger. The moths got a little grayer. And then very, very slowly, over generation after generation, after generation of moths, they get a little bit darker, and then darker still. Until you end up eventually with a population of moth that turns completely black. That's the classic story. Except that we now know that's wrong. It turns out it wasn't slow. It didn't take generations and generations.

Sequencing of the moth genome has revealed a stretch of DNA, 22,000 letters of the DNA code that suddenly jumped into these moths from somewhere, and in a flash, the moths changed from white to black. Pretty much in one day, really, a white-peppered moth mom all of a sudden produces an all-black. baby. Wait, so how did that, how did that happen? They said a whole packet of genes just got shoved in to this new, from where did it come from? Well, David says it probably jumped one part of the moth genome to a completely new part, different part. But what that means, of course,

is that living things, it turns out, can change way faster than we thought. And therefore, evolution can happen much faster than we thought. And on top of that, David says, scientists have now discovered there's an even stranger kind of super fast change that takes things about parents and offspring, individuals, species, things we've counted on for years and just throws the whole mix into the air.

Yes. Infective heredity. Infective heredity. What is that? Oddly enough to explain this to you, I have to go back. Hello, I'm Chad Abramrod. And I'm Robert Crowellwood. And this is Radio Lab.

To an earlier version of us. because it was 11 years ago, I think, that we made a show called So-Called Life. Life, not as we know it. Oh, God, that show. And in that show, we dealt with an early sort of more primitive version of this very question. So I'm just going to play you a few minutes of that earlier show. Well, let's talk about Life, you and I.

And we'll come back. When you look around in the world at living things, and I say, look, Dad, there's a cat, and that is a dog, and that's a tree. And you notice that those things, of course, are different. Yes. And later when we go to school, we learn about phyelms and categories like kingdoms and stuff. So we learn about the nature of those differences. And then you're taught about struggle and competition, Darwin and species and all that.

There is a new theory that's being talked about that turns all of that on its head. I heard it first from this guy. I'm Steve Strogettz. I'm an applied mathematician at Cornell. And the story he told me, which is based on analysis of DNA and very tiny organisms, microbes. Is that once upon a time, he says, life began with a very primitive, very simple collection of cells.

And these cells, said Steve, these cells like to share. It appears that when you go back far enough, there's a kind of rampant sharing of molecules. It's a kind of orgy in which there are no well-defined species or organisms, and I can give you my genes and you can pass, we're a commune. I totally remember. recording that. The kumbaya singing. That's Saren Wheeler who was there at the start. He produced

this piece years ago. Yes. I think it was just us around the office, humming. Yeah. It was a commune. What does that mean? What does that mean? What does it mean? I mean, I know what it means in the 60s. Free and love sense, but what does it really mean? What cells are exchanging is chemicals. Chemicals that give them talents and traits genes. Here's what happens. I did this with Steve. In our ancient puddle, when Darwin thought that life might have begun in a warm puddle. Let's say that you and I are both cells. Okay. So once upon a time there was you in a puddle, and I'm in the same puddle as you, and it gets a little colder in the puddle, so we should all get sick. But you don't get

sick. You have some kind of accidental talent. You can handle cold water. I'm shivering. Describe again what happens at this point, in the glorious old days. Well, my membrane, that is, I'm a cell, I've got a membrane, I've got my outer layer, maybe a little bit porous, and maybe... Whoops, some of my genes just leaked out. Okay? We're not talking sophisticated organisms. And maybe you're porous too, and...

Oh, whoa, you just absorbed some of those genes. So now we both have this... We both got it. We both got it. And if I've got this gene now, I can survive cold water because it's part of me. And if I bump into you, now it's part of you. So now this Steve gene has become a Robert gene,

which has then become a JAG gene, doing this over and over and over. And we're getting really, um, commune. It sounds so friendly. No, no, actually, don't think of cells like people. Shut up! All these exchanges, this gene swapping, was not intentional.

It's not purposeful sharing. That's Nigel Goldenfeld. I'm a theoretical physicist at the University of Illinois. And he and his colleague, Carl Woz, did the science that led to some of these kind of goofy ideas. It's not me sort of saying, hey, I'm going to just help out my buddy over there. Here's a couple of genes that I think you'll think you'll find handy. It's not something like that. Even still, if we're swapping genes so much and, you know,

you're giving me yours and I'm giving me mine, what does it actually mean to be me? Yeah. If so much of me is spread around. Well, it would be very weird. Imagine a world in which for a while I have your nose. God forbid. And then I get my nose back. You'd have Steve's hair. Then Steve would get my ear. Then he would get your nose. Once you start having a lot of exchange. I'll take your chin. Okay. You can have my allergies. Then you start even asking, what does it mean to be a species? You can have my love affair with doubt. You may not even be able to talk about individuals.

Yeah, if the mixing is good enough, we're all kind of indistinguishable. So identity would be very strange in this ancient world. A lot of the concepts that we take for granted in biology become more and more nebulous as you get further and further back. to the root of the origin of life. Take, for instance, Charles Darwin. What Nigel's really saying is that for the first billion years of life, with a bee, with a bee, everything that Darwin teaches,

all that stuff hasn't happened. There's no borders, no individuals, there's no species. That is Darwinism, evolution as we now understand it. That's an interlude in the real story of life. It's only what's happening now. What you got back at the very beginning was a whole bunch of cells swapping genes, swapping advantages, swapping disadvantages, and it's kind of a world.

wild time. A tremendous explosion of diversity in a way that life has not seen since then. Until... One dark and terrible day. Three billion years ago. As interpreted by Freeman Dyson. Freeman Dyson. The famous physicist and delivered here now by our friend the mathematician Steve Stroggas. Here's Steve. One evil day, a bacterium anticipating Bill Gates by three billion years, refused to share.

refuse to share. The first bad guy is this cellular Bill Gates who decides that I've got an innovation that I don't feel like sharing. Or possibly I found a way to keep my membrane from leaking. That is, I'm not going to be a sharing soul anymore. And why? What made that one little cell decide to stop sharing? That's a good question. We don't really know.

But what we do know. This was maybe the most dramatic moment in the history of life on Earth. this transition from the age of, if you want to call it, the age of sharing to the age of selfishness. And gradually, once one creature stopped sharing, pretty soon the others followed, and then more and more did the same thing, and now, for the first time in the history of life, finally we get Darwin, now we get species, now we see differences.

Yes, it's the age of identity, of individualism. It's also the age of stasis. Things change, but they change much more slowly. And any great thing, You know, like you are a bat and you figured out sonar. I don't have sonar. I can't get sonar. Be nice to have sonar.

Like, you're in a little electric fish that lives in the muddy waters of the Amazon. You don't care. It's totally dark. You can see because you can see with electricity. I can't see with electricity. If I'm in the dark, I'm bumping my head. Did we really use Bill Gates as a stand-in for, like, selfishness? Yeah, well, I mean, at the time, he was the ultimate corporate.

Oh, that's horrible that we did that. I'm giving out the case foundation. That's right. He's actually gone over to the light side instead of the dark side. Yeah, right, exactly. That is Steve Strogetz. I ended up calling him up just to chat him through some of this stuff. And he told me that he actually heard this whole idea from a lecture by physicist Freeman Dyson.

Dyson is just a great writer and a great speaker. And he had this memorable line in there, at least memorable to me, when he started talking about, I mean, he phrased the whole thing in terms of sharing, which may be why in that previous episode we had that comming. by us singing. That wasn't my doing, by the way. No, no, that was us. But anyway, so then he said, but one evil day, some primitive bacterium, anticipating Bill Gates by three billion years refused to share its DNA. Oh, so that was Freeman Dyson.

That's his, yeah, that was his joke. So anyway, I was sitting there in this lecture, and he started mentioning a certain biologist, Carl Wows, and he talked about him in such glowing terms as one of the great microbiologists of our time. And so you hadn't heard of Carl Woz? I had before. No, I had not. So the reason I was asking is...

I think in the show, we actually mentioned Carl was, as I remember it. You know, I don't know if you guys know this or not, but so that was 11 years ago, right? I was actually an intern at the time. I just showed up. And I was tasked with tracking down Carl Woz, who's the guy that we mentioned as sort of like the grandfather of this idea. And he was like a huge, huge deal in science. He discovered this whole other branch on the tree of life, the Archaia. Oh, he's Mr. Archaia?

Which is a pretty big one. It's a whole other kingdom of life. Yeah. It got him on the front page of the New York Times. And I had to track him down. And it turns out he was like the, just the classic curmudgeonly scientist. It took me 20 emails to get him to even like just let us talk to his collaborator, Nigel Goldenfeld, who we talked to in the show. But whatever.

It was a very strange. He was a very curmudgeonly man. But, you know, like he came to like me and I actually spent some time with him in his office and we,

I can do the curmudgeonly thing if I need to. You know, we shared some. You've got those skills. Yeah, we passed some curmudgeonly jokes back and forth. And anyway, after he heard the piece,

he wrote me the most seething, scathing email about, and nothing there was nothing in it about like you got this wrong it was just like you made a cartoon of my work which honestly now listening back I agree with a little more than I did at the time yeah yeah but he was like I'm a serious person and you made this into like a dog and pony show and I was like I was brand new I was and it hurt and he like I was I felt really really bad and he's like you've disrespected Nigel and so I wrote I wrote to I were called up Steve maybe and said oh

Oh man, you know, this happened. And Steve was like, hey, listen, forget them. Don't worry about it. Oh, I love Steve. Yeah, I don't know. It sounds like something I might have said. But do you remember having that? I don't remember having that conversation.

I honestly don't remember having that conversation. And that was like, oh, I needed that so bad at that moment in my career for someone like with Steve's stature to, like, balance it out in that way. Yeah. Yeah, I think, I mean, it's a little bit funny that he would, to me, a little surprising that he wouldn't have gotten what you were trying to do. Yeah. or what we were trying to do. I think our playfulness, in an attempt to be clear and to communicate, and to attract people who might not otherwise listen to a story

about something called horizontal gene transfer, he should have gotten that because he himself, in his writing, was very playful. He was very fun to talk to. I mean, he was absolutely, Carl Woos was very playful and irascible and grouchy and charming, but he would certainly tell you what he thought. Yeah, yeah, this guy is a great character. And David Quaman, it turns out in his new book, talks a lot, a lot, about Carl Woes and this revolution in our thinking about the evolution of life.

For the end of his life, he started to think that he was more important and more profound than Darwin. He got a very negative attitude toward Charles Darwin. On Darwin's birthday, he sent out a note that everybody said that this should be a day of rage. That's right. Yes, yes, he did that. But what I guess I'm wondering is, now that you spent a book's attention on him, do you feel that he has some right to say that the picture we have of how life changes needs serious amending, or is he just barking because he's a barker?

No. He was entitled, not to think that he was greater than Darwin, but to think that what he discovered was very, very damn important to understand. understanding the full history of evolution on Earth. What has happened all throughout the history of life on the planet, four billion years, and is still happening today. This is where we are now. The crazy details coming up right after the break. This is Young Yun calling from Astoria, New York.

Radio Lab 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. Chad, Robert, Radio Lab. And we're back with David Kwanman, and this new, due to us way of changing life. Infective heredity, these leaping genes, these transfers of DNA that create new genetic possibilities in a blink. Turns out, David told us that the swapping of genes that we talked about in the early history of life, That's still happening today.

Correct. Yes. Bacteria all around us. Those bugs are trading genes. Genes are jumping sideways from one kind of bacterium to another. Even in our bellies, even in our guts. So let's say that you go to France on a vacation and you touch something there and then you lick your finger. I don't know.

Or you eat something. Now, new bacteria from that European food is going to enter your stomach and, Now, not only do you have some new bugs in you, but they can start trading their genes with bugs that are already in you. Yes. What would that mean, like, physically? Like, would it, like, bloop out the cell wall and then... Well, they found that there were several different mechanisms for this. Two bacteria would create a little pipe, a little sort of penis-like thing between them, and genes would be transferred.

But genes were moving sideways under other circumstances, too. from dead, busted open bacteria into live bacteria. Does it acquire this new trait at once? Immediately. Immediately. So in an instant, a new population, even a new species of bacteria, can possess all of those gradually, laboriously acquired adaptations that another strain of bacteria evolved. These bugs, they don't have to wait around for generation after generation to pick up random mutations.

Our bacteria insiders can pick up whole new abilities and new tricks all at once from their new neighbors. So, for instance, one kind of bacteria could pass genes for antibiotic resistance to another completely different kind of bacteria. So say you've got somebody sitting in a hospital with a steflococcus infection. Some of the bugs insider have figured out how to resist penicillin. When that bug then comes out of that human and it gets left on a table. in a hospital and somebody else gets infected by it, then they will also have an infection that is resistant to penicillin. But if, say, they happen to be in the hospital sick with something totally different, they have a

different kind of harmful bacteria giving them trouble. Then those old bacteria in them can learn in a flash from the new bacteria. Now everybody's penicillin resistant. And that's why antibiotic resistance is spreading around the world, so lickety split. That is really important. That's a global health crisis. And the World Health Organization, among others, have called that a global health crisis. Tens and tens and tens of thousands of people are dying from that.

So that's really important and urgent. But the most important part of this whole subject is not practical. It's a matter of understanding, understanding the history of life, understanding who we are. Quite literally, because according to David, the way we are, we humans are has been affected by visits from other creature's genes. Yes. 8% of the human genome is viral DNA. 8% of the human.

That DNA has come into humans or into our mammal ancestors sideways. So here's how that goes. Like, you're sitting around, and a virus gets into your bloodstream, and it travels into one of your cells. And when it's in there, it drops some of its DNA into your DNA. And if it gets into an ovary cell or a sperm cell, well, then it will be passed along. So we, 8% of our genome has come to us that way from these viruses. Some of that is just gobbledygook in our genome, and some of it is instructions,

in other words, genes that are still performing functions. And one of those creates a boundary layer between the human placenta and the fetus, an absolutely necessary, essential boundary layer. Now, this came as a total shock to me, because after all, the thing that's really special special about mammals is that female mammals, or at least placental mammals, carry young around inside the body. In the history of life, this was a completely new development. I mean, you think about fish, you think about reptiles, like the dinosaurs, you think about the birds.

What do they do when they have kids? They lay eggs. But now we get a creature that comes along and figures out how to keep the baby growing inside it. Of course, if it does that, it has to make sure that its immune system doesn't attack that baby, and the baby has to be able to poop and stuff like that and get things out. So there has to be some kind of boundary. And how did we get that good idea? Well, we got that good idea from a virus.

Long, long ago, some ancient mammal ancestor got a virus, got infected by a virus, and that virus introduced a new gene. The original virus, it created an envelope, a wrapping around the virus. But it has been adapted to create a different kind of wrapping, the wrapping that goes around the fetus and inside the placenta. So it carries nutrients in. It protects the fetus from the mother's immune system. And it is allowing waste products from the fetus to be carried away and disposed of by the mother.

I mean, is this potentially the origin of mammals? And this being the without which, if we hadn't gotten this talent from viruses, we wouldn't have gotten the kinds of mammals that we have now? that that layer could not exist and does not function without this viral gene telling it what to do. Without this little bit of virus DNA, you can't be a mammal. You can't be a mother mammal and you can't be a child. In light of this stuff, and for me, in light of five years of studying it and following it and interviewing people about it, the categories that we apply to the world,

categories like individual and species now appear more blurry. The edges are fuzzy. Is there such a thing as a human individual or is a human, a composite of other forms of life? And what this says is that we are composites. We are mosaics. It's humbling and it's fascinating to think of yourself that way. Like for me, David. So it turns out that David is not just the descendant of a Norwegian father and a German-Irish mother,

but he's also viral and bacterial and who knows what else. And I find that thrilling. I'm grateful to all those other limbs on the tree of life for the things that they've given us. Thanks, of course, to Stephen Strogetz of Cornell University, who was always willing to jump back into the ponds which he long since had left and thought he'd gotten dried off from. David Quarman's new book is called The Tangled Tree, and it's a gorgeous book.

So, thanks to them. And thanks to all of you for listening. I'm Chad I'm M.Rod. I'm Robert Kulwitch. We'll see you next time. Wait a second. Is that Kumbaya? It's a sly version of Kumbaya.

You snuck it in. You're snuck it in. You Trojan horse did. My name is David Morn and Ogunnea, calling from Mexico City. Radio Lab was created by Jet Abramrod and is produced by Soren Wheeler. Dylan Keeffe is our director of sound design. Maria Matasar Padilla is our managing director. Our staff includes Simon Adler, Becca Bresler, Rachel Cossack, David Gebel, Bethelhaft, Tracy Hunt, Matt Kilty, Matt Kielty, Robert Kulwich, Annie McEwen, Latif Nassar, Melissa O'Donnell, Arian Wack,

Pat Walters and Molly Webster. With help from Shima Oliai, our fact checker is Michelle Harris.