[RADIOLAB INTRO]

JAD ABUMRAD: Hello, I'm Jad Abumurad.

ROBERT KRULWICH: Hello, I'm Robert Krulwich.

JAD: This is Radiolab, the podcast.

ROBERT: Which means it's not the broadcast.

JAD: Not the one-hour show.

ROBERT: No, not the one-hour show.

JAD: This is like a little tidbit.

ROBERT: This is a tidbit, but this is a tidbit with a teasing purpose.

JAD: Yes.

ROBERT: Because we have—in the next few weeks, we are going to do the real shows about race, and there's one about choice. There's one, however, entirely devoted to the subject of sperm. And sperm, you think, "Well, why would you spend so much time talking about that?"

JAD: Yes. In fact, it's a very sad, sad and lonely show. But anyhow, go on.

ROBERT: [laughs] We learn a lot of—I mean, if you open up any little basket and ask too many questions, you learn all kinds of fascinating things.

JAD: That's so true. Particularly with sperm.

ROBERT: Yes. So we talked when we were preparing this hour with a woman named Joanna Ellington, a fertility expert who runs a company with a very short name—kind of like sperm itself. ING. I-N-G. It's a fertility firm. And I asked her if you are a healthy male at the very top of your game, so you've got everything you're ever gonna have and they're all frisky little guys, ready to go, what proportion of your gang would be fit and ready to do the deed?

JOANNA ELLINGTON: A normal ejaculate from a man is if you have 14—one four—14 percent or more of the sperm that are normally shaped. That's a very low percent.

ROBERT: And 86 percent are abnormally shaped?

JOANNA ELLINGTON: Yeah.

ROBERT: How do they differ from the normal?

JOANNA ELLINGTON: Typically, you're gonna have problems with the tail. And then that makes it so they can't swim right. They swim in a circle, can't swim fast.

ROBERT: Some of them swim in a circle?

JOANNA ELLINGTON: Mm-hmm.

ROBERT: You mean when they go bang and off you go, they just go round and round and round and round?

JOANNA ELLINGTON: Right. And that doesn't work very well, of course. [laughs]

ROBERT: Okay. Circles, slow. Anything else?

JOANNA ELLINGTON: Yeah. As the sperm get ready to be ejaculated, the tail unwinds from around the cell, and sometimes it doesn't unwind right. It stays wound up, or the very tip of the tail stays kind of in a knot, I guess you could say, basically.

ROBERT: [laughs] So you got a knot on your tail?

JOANNA ELLINGTON: Yeah.

ROBERT: Okay. So we got some stalled out, some going in circles, some going slowly. Are there horror, mutant sperm?

JOANNA ELLINGTON: Yeah. There's one called globozoospermia, and that is a very large, round head. It's maybe three or four times normal size, and instead of having that oval, it's just quite round looking.

ROBERT: Sounds like a balloon head. Big, fat balloon head.

JOANNA ELLINGTON: Yeah, exactly. You can have sperm that have vacuoles, which are basically holes in the DNA.

ROBERT: Huh!

JOANNA ELLINGTON: You can have sperm that have two tails.

ROBERT: Ooh!

JOANNA ELLINGTON: Yeah.

ROBERT: Isn't that better?

JOANNA ELLINGTON: [laughs] No, you don't want anything abnormal.

ROBERT: Are there double-headed ones?

JOANNA ELLINGTON: Yes, absolutely.

ROBERT: Are there triple-headed ones?

JOANNA ELLINGTON: Um, probably some.

ROBERT: This is making me nervous.

JOANNA ELLINGTON: [laughs]

ROBERT: Anything else?

JOANNA ELLINGTON: Some of them are going to be dead and not moving at all.

ROBERT: Well, that's a problem.

JOANNA ELLINGTON: Yeah. In addition to that, there's many, many micro biochemical things that they have to go through. So if you were to actually write down everything that could go wrong with sperm as it meets—goes to meet the eggs, it would be hundreds of little enumerations that could go wrong. But that's why men make sperm all the time. They constantly are making it, they constantly have a fresh supply. You've got to have something that can go through all the hurdles and all the barriers, and make sure at the end of the day that you have the best, healthiest sperm cell that's participating in making a baby.

ROBERT: When you say, Jad, that it's lonely ...

JAD: That's sad.

ROBERT: With odds like that, remember, this is when you're healthiest.

JAD: I know.

ROBERT: When you're healthiest.

JAD: What I don't get, though, is, like, how does it—how does it—well, this is what we're gonna go into in the show, but I'll just ask you now: how does it happen, given all of those potential pitfalls and that every sperm is outracing the other sperm as well?

ROBERT: That's the public image here, is that every guy that you put in is in a Woody Allen movie sense, competing against his neighbor.

JAD: Right.

ROBERT: So it's Jerry versus Ted versus Andy versus Mark versus Freddy versus Billy, and they're all rushing to the goal.

JAD: And what if Jerry and Ted and Mark and Freddy and whoever, and Billy are all double headed with ...?

ROBERT: Well, then they don't make it.

JAD: So it's the odds are not in our favor.

ROBERT: But there is a level of cooperation we discovered while doing this hour that was deeply surprising. Sperm are not always about competing against each other, and this we learned from Tim Birkhead, who's a biologist at the University of Sheffield. He told us the story about it was a wood mouse. A W-O-O ...

JAD: Not a could mouse or a should ...

ROBERT: No, not a should mouse. This is a wood ...

JAD: A wood mouse.

ROBERT: Yes, wood mouse. Which is actually a gift wood mouse.

TIM BIRKHEAD: My colleague Harry Moore, who's a sperm biologist here in Sheffield, his cat brought in a wood mouse, laid it on the dining room floor, and he looked at it and thought, "Gosh, that's got large testicles." He dissects it.

ROBERT: [laughs]

ROBERT: That's the most unusual reaction to a cat's gift that I've heard in a long time.

JAD: I'll say.

ROBERT: You know, if you're a testicle guy, you're a testicle guy.

JAD: You want to take a closer look.

ROBERT: Anyway, so he dissects the—He dissects the mouse, and then carefully removed the sperm inside. And then he looked at the shape of the sperm. This was interesting.

TIM BIRKHEAD: All rodents, the sperm has a slightly hooked-shaped head. But in the wood mouse, that hook is extreme, so much so that the hook bends right back and touches the head again. And what Harry noticed was that it looked as though the hook was a specific adaptation to grasp the tails of other sperm.

ROBERT: And this sperm, on its head was a kind of grasping hook, which suggested that maybe this sperm wanted to hold hands with something.

TIM BIRKHEAD: Harry put the sperm into a kind of special sperm medium and to his amazement, the sperm all joined up together in what he called sperm trains.

ROBERT: Sperm T-R-A-I-N-S?

TIM BIRKHEAD: Yes. Like in a railway train. The tails of other sperm were held by this hook.

JAD: And it's just head to tail, head to tail?

TIM BIRKHEAD: It looks—it's a bit messy. It's a bit like spaghetti moving forward.

JAD: Okay.

TIM BIRKHEAD: The amazing thing is, when he measured the speed at which the sperm trains moved, it was about twice that of isolated sperm.

ROBERT: But wait a second. If me and 700 others of us, or 10 of us, get together at the head and swim together, our tails all increasing our speed, who gets to be the daddy sperm?

TIM BIRKHEAD: In the wood mouse, some of the sperm undergo what's called the acrosome reaction, releasing this hook. And when that happens, those sperm can no longer fertilize, but they free a vanguard of sperm that then can fertilize.

ROBERT: And then they give up for their brethren?

TIM BIRKHEAD: Yep, that's exactly it.

ROBERT: Whoa! So then it's not fair to say that down there at the sperm level, it's every sperm for himself. In a few cases, the sperm is there for the other guy.

TIM BIRKHEAD: Yeah. But they're all part of the same ejaculate, all got roughly the same genetic makeup. All those sperm are related, so they all have more or less a common interest.

JAD: See? We help each other out.

ROBERT: Yeah. I mean, this is different. However, it is at this point, just specific to the wood mouse.

JAD: Right.

ROBERT: So wood mouse sperm seem to have a thing going on amongst themselves. And the idea that a sperm would sacrifice itself for a brother sperm is very novel when you think about how normally this is thought of as such a competitive event.

JAD: That's right. Well, in any case, we hope you'll tune in for that show. It's coming up in about a month and a half.

ROBERT: It's not really a month and a half if you're listening to this late in the week, it's a month and two weeks from now.

JAD: Okay.

ROBERT: That's a month. It's a month. It's so short. It's really five weeks from now going on four weeks, and before you know it, it'll be three weeks.

JAD: [sighs] Do you see what I deal with? Soren, can you take him down, please?

ROBERT: You can't take me down.

JAD: Just pot him down, please.

ROBERT: Hey!

JAD: In any case, so visit our website, Radiolab.org, or you can find out more about anything on our website. And also, we should say—we should give thanks. We are funded by the Corporation for Public Broadcasting.

ROBERT: Hey, wait!

JAD: Hey, take him down! The National Science Foundation and the Alfred P. Sloan Foundation, who this month is honoring Flash of Genius, the winner of the 2008 feature film prize in science and technology at the Hamptons International Film Festival. I'm Jad Abumurad. Okay, you can put him back up now.

ROBERT: Robert Krulwich. [laughs]

JAD: We'll see you soon.

ROBERT: Very soon.

-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.