Jad Abumrad: I thought we would begin by looking backwards at a wonderful moment in the history-- cinematically, of parasites.

Robert Krulwich: The cinematic history of parasites?

Jad: Yes. Do you remember that movie-- I'm not going to tell you the name of it. it starts outs-- in fact, I have the script right here-- Setting.

[movie plays]

Jad: Space. Vast, empty space. The script continues, "The stars shine cold and remote like the love of God." You're imagining this?

Robert: Yes.

Jad: 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.

[movie plays]

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

[movie plays]

Jad: They're paling around, and you just get the feeling this is a normal day in their astronaut lives. Until--

Robert: What?

Jad: There on the computer radar, there's is a disturbance. Some kind of distress signal.

[movie plays]

Jad: They think, "We ought to check this out," so they trace the signal, eventually get into a pod and [unintelligible 00:01:26].

[movie plays]

Jad: They find themselves at this abandoned ship. Totally abandoned. It's like a ghost ship.

[movie plays]

Jad: It's empty, except for these weird eggs. The astronauts are looking at the eggs and touching the eggs and going--

[movie plays]

Jad: Now fast-forward, we're back into the first ship. Everything's fine for the most part. Then something happens. I've got the computer there in front of you. Push the space bar.

Robert: All right.

[movie plays]

Jad: Describe what you're seeing.

Robert: They're at the table. Everyone's dressed in white.

[movie plays]

Robert: They're talking and chatting. They're all having salad.

Jad: They're just eating and talking.

[movie plays]

Jad: One of the guys gets a little weird, right?

Robert: He's not feeling so good, one of the guys.

Jad: What's he doing?

Robert: Now he's coughing.

Jad: Coughing?

Robert: He's having trouble breathing. He's falling back onto the table, his chest is heaving his wrist-- oh, my God. He's shaking his head wildly and flexing all over the table and something-- he's like-- oh. Oh, God.

[movie plays]

Robert: There's a red thing. A red, horrible, snakey 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 hisses.

Robert: Why did you make me see this?

Jad: I figured out why that scene is scary. When I first saw this movie, that scene went over and over and over in my mind, and it's had this effect on a lot of people. 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: Inside him, incubating, waiting. To think that you, sitting in that seat right there could have in your gut these little worms that are wriggling around and doing more or less what that alien was doing, and I can't even see them in you. I can't even talk about it.

Robert: Let's not.

Jad: We're not doing that. 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.

?Speaker: Maybe I'll just move this.

Jad: 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, and parasites have been on his radar ever since he was a little boy.

Carl: I grew up on a little farm, and my mother would raise tomatoes sometimes in her vegetable garden. Sometimes there would be these caterpillars feeding on them, and my mom would be very annoyed. Every now and then, I would notice-- some of them didn't really look very well. They had this little sort of fuzzy white bumps on them. I didn't really know what they were. 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 it was eating my mother's tomatoes. They were growing.

Jad: Growing inside the caterpillar.

Carl: Then finally, when they were ready, they came out, and only then did their host die.

Jad: When he finally found out that that is what was happening inside those fuzzy white bumps-

Carl: This profound situation--

Jad: - this whole universe of babies growing into adolescence.

Carl: That's when I got very hooked.

Jad: Which is probably an understatement because you are P, Parasite Man. 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: People have been dismissing parasites for a long time calling them degenerates. 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 a lawyer for them? "Hey, sir, you called this degenerate. How dare you, sir, say that?"

Carl: 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: It's not independent.

Jad: When you say it's not degenerate, why do you say that?

Carl: Let's start with saying it's not independent. Are any of us independent?

?Speaker: Kit Carson.

Carl: If you stripped all of 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: 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: My point is that Daniel Boone eats meat. He ate bread which came from plants.

Jad: It's a question of degrees, though. We're not living inside the intestinal tract of some other creature.

Carl: Why does living inside seem like it's a degenerate thing as opposed to us? We can't even synthesize a lot of our own vitamins anymore. We're degenerates in a lot of ways.

Robert: No, Carl. If you are a creature that lives off someone elses' vitality--

Jad: Cheaters would be another way of putting it.

Carl: Listen, can you appreciate how hard it is--

Jad: I'm just going to cut this short right here. Carl says no.

Carl: No, they're amazing.

Jad: Time and time again he says, "No."

Carl: No.

Jad: The argument went on.

Carl: I'm still waiting to hear about how you are able to photosynthesize [crosstalk].

Robert: I eat plants that do it for me, but I go about in a mental way.

Carl: You can't even do it yourself [crosstalk].

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

Lulu Miller: Yes?

Jad: Come. You're going to be the-- You get that mic right there. You're going to be the moderator. You listening right now, we will leave it to you. Your decision. In this one lightning round of-- Go ahead.

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

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

Jad: Big wasps, small wasps?

Carl: They're generally pretty tiny.

Lulu: They go after all sorts of things.

Carl: So some will lay them [crosstalk].

Lulu: Carl's caterpillars, spiders, or the one Carl's going to tell us about.

Carl: This particular wasp is called is ampulex compressa.

Lulu: Goes after--

Carl: Cockroach.

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

Carl: What it does is it flies around, and it looks for a cockroach. Once it finds that cockroach, it lands.

Lulu: Then the fight begins.

[music]

Lulu: 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: And stings it.

Lulu: Right in the belly. The cockroach twitches for a second and then falls.

Carl: 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: Delivers a second sting. The stinger actually threads its way to a particular spot in the brain.

Lulu: This does something odd. Moments later--

Carl: The cockroach recovers. It stands up. It can walk again.

Lulu: Something is wrong. Very wrong.

Carl: It just stands there.

Lulu: I'm awake, but-

Carl: It can't run away.

Lulu: - I can't move.

Carl: It has essentially lost its will.

Jad: What does that mean?

Carl: It's a puppet.

[music]

Carl: It is a puppet. It's become a zombie basically. Now the wasp will literally grab onto the cockroach's antenna and start pulling on it.

Jad: How does it grab? With what does it grab?

Carl: I believe with its mouth.

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

Carl: Like a dog on a leash.

Lulu: It leads it down, down, down.

Carl: Down into a little burrow it's made, and the cockroach is, “Okay, wherever you want to go.”

Lulu: Then once the wasp has the roach in the burrow--

Carl: It lays its eggs on the underside of the cockroach.

Lulu: Now you've got this drugged roach sitting on top of some wasp eggs, and then the wasp-

Carl: Goes out and it seals the burrow.

Robert: It buries the cockroach alive, like it puts him in a cell?

Carl: It's in a little chamber. It doesn't want to kill the cockroach because this cockroach is going to feed it's-

Robert: Young.

Carl: It’s young, yes. Then the eggs hatch and then they drill inside the cockroach, which is still just sitting there.

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

Carl: Parasites are very careful. They won't eat vital organs that will kill it.

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

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

Jad: Wow. Then what happens?

Lulu: Eventually, the little baby wasp larva grows up inside the cockroach.

Carl: And develops into an adult.

Lulu: Then one day--

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

Jad: Then the roach dies.

Carl: Then the roach dies.

Jad: [unintelligible 00:11:37].

Carl: Yes.

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

Carl: Darwin certainly said that God should not be personally blamed for having created parasitic wasps.

Lulu: If you ask Carl, how do you think about that moment, the moment where the wasp stings the brain?

Carl: 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: It has performed a brain surgery.

Carl: Very precisely, in a very elegant way.

[laughter]

Jad: Or evil, it might be the other way. Go ahead.

Carl: There's a complexity there that you can't deny.

Lulu: Can you? We leave it to you, bringing us to example Number 2.

Speakers: Parasitic nematodes.

Carl: Here’s another example that I actually was looking up today.

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

Lulu: On the screen is a big Black ant.

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

Carl: Right.

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

Carl: 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 it's butt?

Carl: Essentially, yes. [chuckles]

Jad: Wait a second. It looks like it's sticking its big red butt up into the air.

Carl: Yes, their behavior is changed. They waggle around their tail as it were.

Lulu: Now why on earth would a parasite turn an ant’s butt red, and then make it stick its butt up into the air? Well, Carl.

Carl: Let's say you put an ant down that has this bright-red rear end and an ordinary ant in front of a bird. A bird is going to go for that red ant very quickly.

Jad: Because it thinks it's a berry.

Carl: Yes.

Robert: Then, what?

Carl: It's going to swallow this little package full of nematode eggs.

Robert: That's the way the nematode eggs get into the sky. They buy their airplane tickets by advertising themselves as berries?

Carl: Yes.

Jad: What's the benefit of being in the air?

Carl: The only place that this parasite can reproduce is inside the bird.

Lulu: How better to spread your seed far and wide than to drop from the sky.

Carl: With the bird’s droppings.

Jad: That is [sound cut] brilliant. That's [sound cut] brilliant. It's red [sound cut] is up in the air. It's amazing. It's like how can a stupid little thing be so brilliant?

Carl: Because they're not degenerates.

[laughter]

Jad: They're still cheating.

Lulu: Then, just to bring this point home.

Carl: Just to pick a common one.

Lulu: Carl offered up his third and final example, Number 3

Speakers: Blood flukes.

Carl: Blood flukes are related to flatworms, tapeworms, so their eggs start out in the water.

[music]

Carl: Freshwater in Africa, Asia, parts of South America.

Lulu: The first part of their life, they go into a snail, and they come back out into the water.

Carl: They're swimming around, and they start looking for a human.

Robert: Imagine a foot going into the shallow end of a pond. I see toes. I see bottom of foot. I see ankle.

Carl: If you’re a blood fluke, you don't see anything. You don't have eyes.

Robert: Oh, sorry.

[laughter]

Lulu: Eventually, you find a foot, secrete a little enzyme.

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

Robert: A mate?

Jad: There's sex. There's a male and female is what you’re saying?

Carl: True. They're animals.

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

Carl: The female is very thin. It's a standard-issue worm thing, but the male is very strange. It's like a canoe. It's got a big trough down the middle. At one end, it's got a giant sucker.

Robert: Should we urge some of our listeners to tune away at this point because but it's about to happen may not be acceptable in family hour.

Carl: [chuckles] Actually, blood flukes are fairly monogamous and loyal. If you're looking for animals to reinforce your family values, blood flukes are pretty good.

[laughter]

Lulu: Eventually, two blood flukes find their way toward each other, and the male does a courtship.

Carl: For whatever reason, the female says, “Yes, I accept your courtship.” The female joins the male, so it fits in the trough.

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

Carl: This isn’t mating; this is way beyond mating. The males will feed the female for starters.

Lulu: They will stay this way for--

Carl: A long, long time.

Jad: Really?

Carl: Yes.

Jad: Like days?

Carl: Years.

Speakers: Years?

Carl: Yes.

Robert: Oh, my God. Years in human-time or years to them?

Carl: Just years, years, years, years.

Robert: Years is like the earth going around the sun years?

Carl: Yes.

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

Carl: “Oh, you've got blood flukes. Now you had to have been in Africa to get this disease. When have you been in Africa?” The person said, "40 years ago."

Jad: What? 40?

Carl: Yes.

Jad: Four, zero?

Carl: 40 years ago, yes. The reason that they're getting sick is that these male and female blood flukes are still together making eggs.

Lulu: Carl's literally glowing when he says this.

Carl: I have to admit, I do love the thought that parasites are among the most monogamous animals on the planet. It's heaven. You're going to spend the rest of your life together.

Lulu: Our story concludes with the image of two blood flukes spooning in your veins for nearly half a century.

Jad: You got to hand it to him, he's good.

Robert: Carl, you mean?

Speakers: Yes.

Carl: There is a species of tapeworm that's going to be named after me.

Jad: No kidding?

Robert: Really?

Carl: Yes.

Jad: Wow.

Carl: 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 expert about how she was going to name one for me. Then they got into a conversation about, "That was going that you named that particular tapeworm for him because he's thin, and it's a thin tapeworm. My aunt, she's a little round, and it's a round tape that I named her after. You'll just suddenly discover there are a lot of tapeworms to be named."

Jad: How many is a lot?

Carl: Tens of thousands of species of tapeworms.

Jad: Wow. They got us beat many times over.

Carl: I once saw estimates that if you took all the viruses in the ocean and you stuck them end to end, how far would it go? 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: Oh, yes.

[music]

Jad: We should go to break, don’t you say?

Robert: I think we should.

Carl: 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 fluke spooning the ant with a swollen red butt, and of course, the wasp with the cockroach.

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

Jad: At radiolab.org.

Jad: I'm Jad Abumrad.

Robert: I'm Robert Krulwich.

Jad: Stay with us.

Carl: 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. Bye.

Copyright © 2020 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 New York Public Radio’s programming is the audio record.

Unlock member-only exclusives and support the show

Exclusive Podcast Extras

Entire Podcast Archive

Listen Ad-Free

Behind-the-Scenes Content

Video Extras

Original Music & Playlists

Unlock exclusives in The Lab

Sign up for the newsletter