[RADIOLAB INTRO]

JAD ABUMRAD: I thought we would begin by looking backwards at a wonderful moment in the history cinematically of parasites.

ROBERT KRULWICH: A cinematic history of parasites?

JAD: Mm-hmm. Okay, so do you remember that movie—I'm not gonna tell you the name of it—starts out—in fact, I have the script right here. Setting: space.

ROBERT: Okay.

JAD: Vast empty space. The script continues, "The stars shine cold and remote like the love of God." Are you imagining this? Now floating in that vast nothingness is a tiny dot of a ship. You can barely see it. Cut to the interior of the ship."

[ARCHIVE CLIP, Alien: Ugh, I feel dead.]

JAD: Here we are in a ship full of astronauts who are tired and dirty.

[ARCHIVE CLIP, Alien: Anybody ever tell you you look dead?]

JAD: They're just palling around and you just get the feeling this is a normal day in their astronaut life, right? Until—there on the computer radar is a disturbance. Some kind of distress signal.

[ARCHIVE CLIP, Alien: A transmission. Out here?]

JAD: They think, 'We gotta check this out.' So they trace the signal, eventually, get into a pod, and—whoosh! They find themselves at this abandoned ship. Totally abandoned. It's like a ghost ship.

[ARCHIVE CLIP, Alien: I've never seen anything like it.]

[ARCHIVE CLIP, Alien: I wonder what happened to the crew.]

JAD: It's empty except for these weird eggs and the astronauts are like looking at the eggs and touching the eggs and going. Okay, now fast forward. We're back into the first ship.

ROBERT: Okay.

JAD: Everything's fine, for the most part. And then something happens and I want you to—I've got the computer there in front of you.

ROBERT: Okay.

JAD: Well, push this—push the spacebar,

ROBERT: Spacebar. All right.

JAD: Describe what you see.

ROBERT: They're at the table, everyone's dressed.

[ARCHIVE CLIP, Alien: First thing that I'm gonna do when I get back is to get some decent food.]

ROBERT: They're all talking—chatting. They're all having, like, salad.

JAD: Yeah, they're just eating and talking. One of the guys gets a little weird, right?

ROBERT: Oh, he's not feeling so good, one of the guys.

JAD: What's he doing?

ROBERT: Oh no, he's coughing, coughing, having trouble breathing. He's fallen back onto the table. His chest is heaving—his wrist. Oh my God! He's shaking his head wildly, and he's like flexing all over the table. And something he's like, right—oh! Oh, God! So there's a red thing, a red horrible sneaky thing.

JAD: This is, of course, the classic scene from the original Alien movie. The scene where the little thing bursts out of the guy's chest and like hisses.

ROBERT: Why did you make me ...

JAD: Because I think I figured out why that scene is scary. I mean, when I first saw this movie, that scene went over and over and over in my mind and it's had its effect on a lot of people and I think I know why.

ROBERT: What do you know?

JAD: It's not that the little creature is disgusting, which it is. It's that it was there all along ...

ROBERT: Sitting there.

JAD: Yeah, inside him. Like, incubating, waiting. To think that you sitting in that seat right there could have in your gut these little worms that are wiggling around doing more or less what that alien was doing and I can't even see them in you? Ugh! I can't even talk about it.

ROBERT: So let's not. Today's subject on Radiolab will be flowers in meadows. Coming up after this.

JAD: No, we're not doing that. We're doing—we're doing an hour on parasites. These little creatures that live inside us, invisibly, and yet can have a huge influence over who we think we are.

ROBERT: What is a parasite, precisely?

JAD: A moocher. Just to sort of slide us in, get us into the mood.

ROBERT: I'm already not in the mood.

JAD: We thought we would get things started.

CARL ZIMMER: Maybe I'll just move this.

JAD: Well, there really is no other way to start a show on parasites except with this guy.

ROBERT: You should introduce yourself.

CARL ZIMMER: My name is Carl Zimmer.

JAD: Carl's a science writer.

CARL ZIMMER: Yeah.

JAD: And parasites have been on his radar ever since he was a little boy.

CARL ZIMMER: I grew up on a little farm and my mother would raise tomatoes sometimes in her vegetable garden. And sometimes there would be these caterpillars feeding on them and my mom would be very annoyed. And every now and then I would notice that some of them didn't look very well and they had these little sort of fuzzy white bumps on them and I didn't really know what they were. Well, it turned out that they had been attacked by a parasitic wasp, which had laid its eggs inside of it. Those eggs had hatched and had become larvae. And those larvae were swimming around inside that caterpillar while I was eating my mother's tomatoes. And they were growing ...

JAD: Growing inside the caterpillar.

CARL ZIMMER: And then finally when they were ready, they—they came out and only then did their host die.

JAD: And when he finally found out that that is what was happening inside those fuzzy white bumps?

CARL ZIMMER: This profound situation ...

JAD: This whole universe of babies growing into adolescence.

CARL ZIMMER: That's when I guess I sort of got very hooked.

JAD: Which is probably an understatement, because you are sort of like capital P Parasite Man.

JAD: And if you look, in the New York Times, or Science magazine, or any of the places Carl writes, a suspicious number of his articles are pretty flattering to parasites.

CARL ZIMMER: People have been dismissing parasites for a long time calling them degenerates. And I would argue that parasites are not degenerate. They have gained the ability to live inside three, four, five, six different species.

ROBERT: Do you find that you're sort of a lawyer for them? Hey sir! You call this degenerate? How dare you sir say that!

CARL ZIMMER: I think I'm a defender of all neglected and put upon species out there.

JAD: Why wouldn't a parasite be what I think you mean when you say degenerate, because the tiny little thing it infects something else, it sucks, whatever ...

ROBERT: Yeah, it's not independent.

JAD: Right. So when you say it's not degenerate, what it—why would you say that?

CARL ZIMMER: Well, let's start with saying it's not independent. Are any of us independent?

ROBERT: Kit Carson?

CARL ZIMMER: Have you stripped all the bacteria out of Kit Carson, Kit Carson would get very sick.

ROBERT: Daniel Boone, on the other hand, now there's a guy. Independent, alone in the woods.

CARL ZIMMER: What does Daniel Boone eat?

ROBERT: I guess Daniel Boone eats pigeon, like the rest of us,

JAD: What's your point, Carl Zimmer?

CARL ZIMMER: My point is that Daniel Boone eats meat. He ate bread, which came from plants.

JAD: I guess it's a question of degrees, though. We're not living inside the intestinal tract of some other creature.

CARL ZIMMER: So why does living inside seem like it's a degenerate thing as opposed to us? You know, we can't even synthesize a lot of our own vitamins anymore. We're degenerates in a lot of ways.

ROBERT: No Carl. No Carl. If you are a creature that lives off someone else's vitality ...

JAD: Cheaters should be another way of putting it.

CARL ZIMMER: But listen, can you appreciate that ...

JAD: I'm gonna—just gonna cut this short right here. Carl says ...

CARL ZIMMER: No, no, no, they're amazing!

JAD: Time and time again. He says no ...

CARL ZIMMER: No, no.

JAD: And the argument went on.

CARL ZIMMER: I'm still waiting to hear about how you are able to photosynthesize through it.

ROBERT: It's true. It's true I eat plants, but, like, go about it in a mental way.

CARL ZIMMER: Until you can tell me ...

CARL ZIMMER:You can't even do it yourself!

JAD: Like I said the argument went on and on with Robert saying one thing and Carl firing back and me adding another. And here's what we're gonna do just to be fair and square about this, we're gonna bring in an independent moderator. Lulu!

LULU MILLER: Yeah?

JAD: You're gonna be the moderator. Yeah, get that mic. You're gonna be the moderator, and you listening right now, we will leave it to you, your decision in this one lightning round of ...

LULU: Shall I do it?

JAD: Yeah.

LULU: Parasites: Are they evil or are they awesome? Starting with number one, the parasitic wasp.

CARL ZIMMER: There are probably 200,000 species of parasitic wasps out there.

JAD: Big wasp? Small wasp?

CARL ZIMMER: They're generally pretty tiny.

LULU: And they go after all sorts of things.

CARL ZIMMER: Some will lay ...

LULU: Carl's caterpillar, spiders or the one Carl's gonna tell us about ...

CARL ZIMMER: This particular wasp is called Ampulex Compressa.

LULU: Goes after ...

CARL ZIMMER: Cockroach.

LULU: And for those of you who never thought you'd feel sorry for a cockroach, keep listening.

CARL ZIMMER: So what it does is it flies around, and it looks for a cockroach, and once it finds that cockroach, it lands.

LULU: And then the fight begins. They tumble back and forth around and around until finally the wasp somehow manages to arch its back around the body of the cockroach ...

CARL ZIMMER: And stings it.

LULU: Zzzzt! Right in the belly. The cockroach twitches for a second and then falls.

CARL ZIMMER: Boom! The cockroach is paralyzed.

LULU: Now the wasp takes its time. Repositions itself, puts its butt up right near the cockroach's head.

CARL ZIMMER: And delivers a second sting. The stinger actually threads its way to a particular spot in the brain.

LULU: And this does something odd. Moments later ...

CARL ZIMMER: The cockroach recovers, sort of stands up and can walk again ...

LULU: But something is wrong. Very wrong.

CARL ZIMMER: It just stands there.

LULU: Like, "I'm awake but ..."

CARL ZIMMER: It can't run away.

LULU: "I can't move."

CARL ZIMMER: It has essentially lost its will

JAD: What does that mean?

ROBERT: It's a puppet.

CARL ZIMMER: Yes, it is a puppet. It's become a zombie, basically. And so now the wasp will literally grab onto the cockroach's antenna and start pulling on it.

JAD: But how does it grab—with what does it grab?

CARL ZIMMER: I believe with its mouth.

LULU: Imagine a tiny wasp guiding a cockroach across the desert floor ...

CARL ZIMMER: Like a dog on a leash.

LULU: And so it leads it down, down, down.

CARL ZIMMER: Down into a little burrow it made and the cockroach says, "Okay, where do you want to go?"

LULU: Then, once the wasp has the roach in the burrow.

CARL ZIMMER: It lays its eggs on the underside of the cockroach.

LULU: So now you've got this drugged roach sitting on top of some wasp eggs, and then the wasp goes ...

CARL ZIMMER: Out and it seals the burrow.

ROBERT: It buries the cockroach alive? Or it just puts him in a little cell?

CARL ZIMMER: It's in a little chamber. It doesn't want to kill the cockroach because this cockroach is gonna feed, it's—you know, it's young. Yeah. So then the eggs hatch. And then they drill inside. The cockroach is still just sitting there.

JAD: How's it staying alive at this point?

CARL ZIMMER: Well, parasites are very careful. You know, they won't eat vital organs that will kill it.

LULU: Instead, Carl says, they just feast on the extra stuff.

CARL ZIMMER: There's a lot of stuff inside of a cockroach, a lot of fluid just floating around.

ROBERT: Bits of Wonder Bread, essence of skin, old hair ...

CARL ZIMMER: That you can just feed on, and the host stays alive.

JAD: Wow. And then what happens?

LULU: Eventually the little baby wasp larva grows up ...

CARL ZIMMER: Inside the cockroach and develops into an adult ...

LULU: And then one day ...

CARL ZIMMER: The wasp eats its way up a hole out of the—out of the cockroach's body, shakes off its wings and flies off.

JAD: And then the roach dies

CARL ZIMMER: Then the roach dies.

JAD: But only then.

CARL ZIMMER: Yeah.

JAD: That to me sounds like the purest description in nature of evil that I can imagine. Wouldn't you agree?

CARL ZIMMER: Well, Darwin certainly said that God should not be personally blamed for having created parasitic wasps.

LULU: But if you ask Carl, he'll have you think about that moment—the moment where the wasp stings the brain.

CARL ZIMMER: A parasitic wasp can attack a cockroach and insert its stinger into one specific part of the cockroach's brain and inject a precise little cocktail of drugs that then turns the cockroach into its slave. I know that that wasp didn't get a PhD in neurobiology.

LULU: And yet it has performed a kind of brain surgery.

CARL ZIMMER: Very precisely in a very elegant way.

JAD: Or evil might be the other way—but okay, go ahead.

CARL ZIMMER: But there's a complexity there that you can't deny.

LULU: Or can you? We leave it to you. Bringing us to example number two: parasitic nematode.

CARL ZIMMER: I mean, here's—here's another example that I actually was looking at today.

JAD: You're holding your computer up to the glass.

LULU: And on the screen is a big black ant.

JAD: It looks like it's carrying a cherry.

CARL ZIMMER: Right.

LULU: A cherry that's about twice the size of the ant.

CARL ZIMMER: That red cherry is actually parasites inside of the ant making it look like a red cherry.

JAD: What part of the ant is that? Is that its butt?

CARL ZIMMER: Essentially, yeah.

JAD: Wait a second, is it—it looks like it's sticking its big, red butt up into the air.

CARL ZIMMER: Yeah, their behavior has changed so they waggle around their—their—their tail, as it were.

LULU: Now why on earth would a parasite turn on ants but red and then make it stick its butt up into the air? Well, caw!

CARL ZIMMER: Let's say you put an ant down that has this bright red rear end and an ordinary ant in front of a bird, the bird's gonna go for that red ant very quickly.

JAD: Because it thinks it's a berry.

CARL ZIMMER: Yeah and then it's going to swallow this little package full of nematode eggs.

ROBERT: So that's the way the nematode eggs get into the sky. They buy their airplane tickets by advertising themselves as berries.

JAD: Yes. What's the benefit of being in the air?

CARL ZIMMER: Well, the only place that this parasite can reproduce is inside the bird.

LULU: And how better to spread your seed far and wide than to drop from the sky? [whistles]

CARL ZIMMER: With the bird droppings.

JAD: That's [bleep] brilliant. That's [bleep] brilliant. I mean look at the—its red [bleep] is up in the air.

CARL ZIMMER: Yeah. It's amazing.

JAD: It's like how can a stupid little thing be so brilliant.

CARL ZIMMER: Because they're not degenerates.

JAD: [laughs] But they're still cheating!

LULU: And then just to bring his point home ...

CARL ZIMMER: Just pick a common one.

LULU: Carl offered up his third and final example number three: blood flukes.

CARL ZIMMER: Blood flukes are related to flatworms, tapeworms. So their eggs start out in the water—freshwater in Africa, Asia, parts of South America.

LULU: In the first part of their life they go into a snail and they come back out into the water.

CARL ZIMMER: And they're swimming around and they start looking for a human.

ROBERT: So imagine a foot, going into the shallow end of the pond, I see toes. I see a bottom, a foot. I see ankle.

CARL ZIMMER: Well, if you're a blood fluke, you don't see anything, you don't have eyes.

ROBERT: Oh. [laughs]

LULU: But eventually you find a foot, secrete a little enzyme ...

CARL ZIMMER: Basically turn a little bit of skin into butter, and you slip into the vein, and now you're going to swim my circulatory system. You're going to ride along in the blood. And now it's time to find a mate.

ROBERT: A mate?

JAD: So there's sex. So there's a male and female you're saying?

CARL ZIMMER: Sure, they're animals.

JAD: They're animals? I would have never called them animals, it's interesting you say that. That's a whole other topic, I guess.

CARL ZIMMER: All right, so the female is very thin. It's sort of a standard issue worm kind of thing. But the male is very strange. It's kind of like a canoe. It's got a trough down the middle, and at one end, it's got a giant sucker.

ROBERT: Should we urge some of our listeners to tune away at this point, because what's about to happen may not be acceptable in family hour?

CARL ZIMMER: Actually, blood flukes are fairly monogamous and loyal. So, you know, if you're looking for—for animals to reinforce your family values, blood flukes are pretty good.

LULU: And eventually, two blood flukes find their way toward each other. And the male does a sort of courtship.

CARL ZIMMER: For whatever reason, the female says, "Yes, I accept your courtship." The female joins the male—fits in the trough.

JAD: Oh, so it's like a groove. The female goes in and occupies the groove.

CARL ZIMMER: Right. Now this isn't just—this isn't mating. This is way beyond mating. The males will feed the female for starters.

LULU: And they will stay this way for a ...

CARL ZIMMER: Long, long time.

JAD: Really?

CARL ZIMMER: Yeah.

JAD: Like days?

CARL ZIMMER: Years.

JAD: Years?

CARL ZIMMER: Yeah.

ROBERT: Oh my God! Years in human or years to them?

CARL ZIMMER: Just years, years, years, years.

ROBERT: Years, like the earth going around the sun kind of years.

CARL ZIMMER: Yes.

LULU: In fact, there have been cases where people show up at their doctor's feeling awful. The doctor does some tests and says ...

CARL ZIMMER: Oh, you've got blood flukes. Now, you had to have been in Africa to get this disease. When have you been in Africa? And the person said, "40 years ago."

JAD: What? 40? Four zero?

CARL ZIMMER: 40 years ago. Yeah, and the reason that they're getting sick is that these male and female blood flukes are still together, making eggs.

LULU: And Carl's literally glowing when he says this.

CARL ZIMMER: I have to admit, I do love the thought that parasites are among the most monogamous animals on the planet. It's heaven. I mean, you're going to spend the rest of their life together.

LULU: And so our story concludes with the image of two blood flukes spooning in your veins for nearly half a century.

JAD: Gotta hand it to him. He's good.

ROBERT: Carl, you mean?

JAD: Yeah.

ROBERT: Yeah.

CARL ZIMMER: And there is a species of tapeworm that's gonna be named after me.

JAD: No kidding?

ROBERT: Really? Wow.

CARL ZIMMER: It's not quite as much of an honor as you think at first. I was talking with a parasitologist, and she was telling her fellow experts about how she was gonna name one for me. And then they got into a conversation about, you know, "That was good that you named that particular tapeworm for him, because he's kind of thin and it's kind of a thin tapeworm. You know, my aunt is, she's—she's a little round and it's a kind of a round tapeworm that I named her after." And you suddenly discover there are a lot of tapeworms to be named.

JAD: How many is a lot?

CARL ZIMMER: Tens of thousands of species of tapeworms.

JAD: Wow. So they got us beat many times over.

CARL ZIMMER: I once saw estimates that if you took all the viruses in the ocean and you stick them end to end, how far would it go? And it was many light years. Way beyond our galactic neighborhood.

ROBERT: In other words, there are more cheats than there are honest people—honest creatures on Earth.

CARL ZIMMER: Oh yeah.

JAD: Should we—should go to break?

ROBERT: I think we should.

JAD: Thanks to Lulu Miller and of course, Carl Zimmer, who has written many books, including, Parasite Rex, a book we shamelessly parasitized for the making of the previous segment. I also want to encourage you to go to our website where you can find pictures of the blood flukes spooning, the ant with the swollen, red butt, and of course the wasp with the cockroach.

ROBERT: Nature porn, and it's all yours.

JAD: At Radiolab.org. I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: Stay with us.

[CARL ZIMMER: Hi, this is Carl Zimmer. Radiolab is funded in part by the Alfred P. Sloan Foundation, the Corporation for Public Broadcasting and the National Science Foundation.]

[LULU: Hi, this is Lulu, leaving you the credits on a landline. Radiolab is produced by WNYC and distributed by National Public Radio. Okay. Bye!]

[ANSWERING MACHINE: End of message]

-30-

Copyright © 2024 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.