328 | Mary Roach on Replacing Parts of Our Bodies

Like any machine, bodies occasionally break down, and it's natural to go in search of a replacement part. Ancient societies featured simple prosthetics for teeth, noses, and limbs, while modern medicine pursues more advanced ways of replacing internal organs and microbiomes. But what is striking is not just the impressive ingenuity of our attempts to replicate human anatomy, but the surprising level of difficulty involved in doing it well. I talk with author Mary Roach about the many ways in which humans have chosen to replace bits of themselves, as told in her recent book Replaceable You: Adventures in Human Anatomy https://www.maryroach.net/replaceable.html. Blog post with transcript: https://www.preposterousuniverse.com/podcast/2025/09/15/328-mary-roach-on-replacing-parts-of-our-bodies/ Support Mindscape on Patreon https://www.patreon.com/seanmcarroll. Mary Roach received a bachelor's degree in psychology from Wesleyan University. Her books include multiple New York Times bestsellers and have appeared on numerous best-of lists. She was a guest editor in the Best American Science and Nature Writing series, and received the Rushdie Award from the Harvard Secular Society. Web site https://maryroach.net/ Wikipedia https://en.wikipedia.org/wiki/Mary_Roach Bluesky https://bsky.app/profile/maryroach.bsky.social Goodreads profile https://www.goodreads.com/author/show/7956. Mary_Roach Amazon author page https://www.amazon.com/stores/Mary-Roach/author/B001H6MAHM

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

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• 0:56Sean Carroll?

  Hello, everyone, and welcome to the Mindscape Podcast. I'm your host, Sean Carroll. A few weeks ago, as I'm recording this, there was some kind of global summit. I'm fuzzy on the details. I didn't really do a lot of research for this intro. But the point is that there was a conversation between Vladimir Putin, who's the president of Russia, and Xi Jinping, who is the leader of China, that was caught on what seems to be a hot mic. In other words, the microphone was turned on, but the speakers didn't actually know that they were being recorded or broadcast, and so they were more candid than they would otherwise be. You might think that they'd be talking about global geopolitics, or trade agreements, or something like that, or even political philosophy.

• 1:37Sean Carroll?

  But no, Putin and Xi were talking about bioengineering and the possibility of immortality, or at least longevity, ultra-longevity. They were saying how advances in biological science were making it possible to replace organs, and if you could go at this rate, you might end up living for 150 years or even more. Subtext being that they would like to live for 150 years or even more. And of course, that's a little contestable, that claim. I mean, there's no contestation to the fact that bio- Engineering and biology more generally are absolutely leaping ahead by leaps and bounds. We're learning a lot, but there's no actual breakthrough that so far has dramatically increased

• 2:21Sean Carroll?

  the upper limit on human lifespans. In fact, this is an issue more generally with sort of the techno-optimist way of thinking about the world. And I say this as someone who is very much attracted to the techno-optimist way of thinking about the world and to someone who does understand the difference between something being literally incompatible with the laws of physics, in which case you should just give up on it, versus something just being really, really hard, an engineering problem, as we call it. And many biological things are sort of engineering problems. But it's too easy to imagine taking biological things and just making them arbitrarily better that turns out to be really hard. It's not that it can't be done. We do it, we're getting better at it.

• 3:06Sean Carroll?

  But biology is very, very, very complex compared to physics, mechanical engineering, even chemistry, things like that. So today's guest, Mary Roach, is one of our leading and also most entertaining science writers that we have. She's the author of books like Fuzz and Stiff and Bonk and Gulp, as well as Packing for Mars. And her new book is called Replaceable You: Adventures in Human Anatomy. And Mary doesn't have, you know, an overarching lesson that she's trying to teach us here, but she goes through a large number of examples, both historically and contemporary science,

• 3:46Sean Carroll?

  of how we replace our limbs and our organs and our skin and our hair and things like that with either other biological things or completely mechanical things. And how, you know, there's been remarkable improvements in a number of ways, but man, is it still really hard. It's still very, very hard to replace an organ in a way that would just bop you back to the level of health you had before. Even, she says, you know, she sort of challenged herself, what is the simplest thing to possibly imagine replacing? And and she came up with a variety of tears that our tear ducts reproduce. We can't do it. It's it's not something that we're able to do right now. So these are things that I'm

• 4:29Sean Carroll?

  very happy to think about in a science fictional way and imagine someday we'll get there. And I'm very happy to cheer along the progress that we have going on right now. But a touch of realism is called for in the near term because biology is tough, man. This is one of the lessons that we've seen over the podcast over and over again. So let's go.

• 5:07Sean Carroll?

  Mary Roach, welcome to the Mindscape Podcast.

• 5:10Speaker 05

  Thank you, Sean.

• 5:11Sean Carroll?

  I guess there's you have written a book called, tell the audience what the title of your book is. So I get the subtitle right and everything.

• 5:18Speaker 05

  Oh, sure. It's called Replaceable You: Adventures in Human Anatomy is the subtitle.

• 5:24Sean Carroll?

  And how long ago historically do we know, like, when did people start actually replacing body parts with non-body part things?

• 5:36Speaker 05

  Things really got rolling with noses, it seems, as far back as like 1500 BCE. People were actually surgically reconstructing noses. And the reason for that is that there was kind of a surprisingly large demand because nasal mutilation was a popular punishment. And this has gone on in various regions of the globe over history where if if if somebody's done something criminal or offensive, or somebody just wants to punish you, they would hack off the nose, which served both as punishment and a deterrent, like, because it's right there in your face.

• 6:16Sean Carroll?

  I guess so.

• 6:17Speaker 05

  So everybody sees, everybody sees it and like, ooh, yeah.

• 6:21Sean Carroll?

  But you can only do it once.

• 6:24Speaker 05

  You can all, yeah. So if you're a recidivist, you're all set. You're like, you know what? I don't have a nose anyway. So what the hell?

• 6:32Sean Carroll?

  I'm trying to decide if I didn't know, would I, you know, think the cutting off the nose or the ear or poking on the eye? Like a nose is very noticeable, but I guess it's not like super damaging if you use it, right?

• 6:45Speaker 05

  Yeah. So I think, yeah, I think it was more effective as a deterrent than as a punishment.

• 6:51Sean Carroll?

  And nevertheless, despite the fact that it was a punishment, they developed the wherewithal to replace the nose somehow.

• 6:58Speaker 05

  Yeah. Yes. Kind of the, the very beginnings of plastic surgery. There was a technique and it's still occasionally used today where you take a flap, flap is a technical term, take a flap from the forehead or they used to use the cheek as well. So you would loosen this flap, but keep it attached to its homeland and then flip it over onto the nose and, and place it there. But it would stay attached to where it's from. So they still had the blood supply while the blood supply was growing in on the nose. And then eventually when, when the nose, the new nose material had some capillaries and some blood supply, then they would cut off, they'd snip the, um, the little isthmus.

• 7:44Sean Carroll?

  And what materials would they use to replace the actual nose?

• 7:48Speaker 05

  The, the, the skin, the cheek.

• 7:50Sean Carroll?

  But like, would they put like bone?

• 7:52Speaker 05

  Oh, oh, oh, bone. Um.

• 7:56Sean Carroll?

  Ivory?

• 7:56Speaker 05

  You know, it was, I don't know what the actual cartilage replacement would. Maybe they just mounted up the flesh, kind of like molded to the flesh.

• 8:05Sean Carroll?

  This is not, this is the first time, but I'm sure not the only time that I'm going to be shuddering while we're having this conversation. It feels a little icky.

• 8:14Speaker 05

  That's a good question. Did they, did they, yeah, did they use anything for the, for the cartilage part? It seemed like they were just kind of molding, like the, using the flesh as like sculpting clay.

• 8:24Sean Carroll?

  That actually seems pretty advanced. Like, you know, knowing that you needed blood and the whole bit.

• 8:29Speaker 05

  I know.

• 8:29Sean Carroll?

  Yeah.

• 8:30Speaker 05

  I was, I was very impressed. Yeah. And, and I was speaking yesterday to a transplant surgeon who said, yeah, we, uh, we, we still do that. I did that last week on a pediatric case.

• 8:40Sean Carroll?

  And where in the world was this going on?

• 8:43Speaker 05

  Well, lots of places, but it started in, started out in Egypt and India were the two places, if you go way back, those were the, and yeah, it was called the Indian method. But I, but I think in Egypt that was done as well. So it's.

• 8:59Sean Carroll?

  The Egyptians, of course, were expert mummifiers. So that maybe they knew a lot about reconstruction for that reason.

• 9:07Speaker 05

  Yeah, it could. Yeah, yeah, it could be.

• 9:09Sean Carroll?

  And of course, I'm a astronomy major from way back. So I know the story of Tiko Brahi, but maybe you could tell the audience that one.

• 9:18Speaker 05

  Yeah. And you even got his name right.

• 9:20Sean Carroll?

  There you go.

• 9:21Speaker 05

  A lot of people say Tyco, Tiko Brahi. Yeah, Tiko. Well, I, yeah, I, I like Tiko because, yeah, he lost a significant chunk of his nose in a duel. And so he, he had a lightweight, fairly lightweight from metal. There's whole papers disputing whether it was brass and amalgam of brass and pewter or whatever. It's unclear exactly what the metal was, but, and he would carry around a little box of adhesive, some kind of glue to stick it on. And apparently, according to one biographer, it would occasionally drop off.

• 10:00Sean Carroll?

  I've seen, I've seen pictures or portrait, portraits, I guess. Do you think that those portraits are, you know, faked a little bit to make it look like a more natural nose? Or was it very obvious?

• 10:12Speaker 05

  No, I think that was, I think it was pretty nicely done. It was kind of painted. I mean, there were, the metal noses and the celluloid noses, noses that were made way back when they were often painted. And in one case, there was a, two different paint colors, one for evening and one for daytime.

• 10:32Sean Carroll?

  Okay.

• 10:33Speaker 05

  Kind of which, you know, if you wear foundation, which I, it looks like you're not, but. If you if you wear foundation, you know, you you can adjust the beauty mirror. What's that called? The makeup mirror according to daytime indoors or outdoors light. So fairly sophisticated nose making. There was an my favorite, however, was from 1894. Frank Tettimore, an army surgeon devised. This was one of the early plastic noses and it it was suspended from a pair of glasses. With that, you know, didn't the person didn't need didn't necessarily need glasses, but so the nose would be suspended. And then to hide the line between the artificial nose and the upper lip, there was a mustache.

• 11:17Speaker 05

  So it was essentially the earliest Groucho Marx glasses ever made.

• 11:22Sean Carroll?

  For men, that works well.

• 11:25Speaker 05

  Yes.

• 11:28Speaker 05

  I never thought of that for the ladies. I'm not sure they did.

• 11:33Sean Carroll?

  But I love the stories just because it it humanizes the past, right? Like, these people cared about how they looked, they, you know, just like we do now. They were doing plastic surgery, makeup. They they didn't want to be embarrassed going out in public.

• 11:48Speaker 05

  Yeah, yeah, and that was true. You know, I I I read a bunch about early dentures. And dentures are surprisingly, they go back to the 1700s. They're there and they were quite elaborate, but they just they didn't work well at all for chewing. So it was like it was like a wig for the mouth. It was a cosmetic thing that you and and they'd somebody described in the Victoria era, Victorian era that that people would use what was called a masticator. So they'd kind of mush, they grind, it looked like a handheld pruners, tree pruners. And you kind of had a little attachment that was sort of blades and a mushing thing. And you'd mush up the food so before you would eat it.

• 12:32Speaker 05

  So people would at a Victorian dinner party, the host might.

• 12:38Speaker 05

  Masticate in private and then put in the very uncomfortable and not useful for eating teeth and then go out to the table and not really eat.

• 12:49Sean Carroll?

  Right, okay.

• 12:51Speaker 05

  Yeah.

• 12:52Sean Carroll?

  And here in the United States, of course, the father of our country, George Washington, was one of these people.

• 12:58Speaker 05

  George Washington, yeah, there's correspondence of George Washington with various of his dentists. George Washington had this type of denture that was held in place. This was before PolyGrip. There weren't adhesives. The dentures, the uppers and lowers were spring loaded, so there's this very stiff spring pressing the upper up against the upper palate and vice versa to the lower. But it also, the spring had a tendency, at least in George Washington's case, to push the upper denture forward out of the mouth. So when you see those portraits of George Washington, he kind of, you know, kind of looks, first of all, he looks really glum.

• 13:38Sean Carroll?

  Right.

• 13:38Speaker 05

  And he also looks like, because he's kind of like, yeah, he's kind of like, holding in his teeth with his upper lip, you know, kind of just holding it in place. Yeah, he was in battle with his own teeth.

• 13:52Sean Carroll?

  And you say, you write in the book about how not that long ago, historically, tooth maintenance technology was sufficiently bad that people would intentionally just have their teeth removed so they could replace them with dentures, which were kind of better looking at the time.

• 14:12Speaker 05

  Yeah, yeah. This was something I'd heard about a long time ago, maybe on QI or something. Matrimonial dentures, somebody mentioned, and I was like, come on, like, that giving somebody the gift of having their teeth all pulled would be a wedding gift. This was something that was done, like, here you go, you'll look better. Yeah, this is, it won't be as expensive, you get them all out at once. And I was like, I'm not buying that. But I went, I found, it was something on Reddit where somebody said, I don't really buy this. Is this true? A thousand, I'm not making that number of a thousand people wrote in saying, my grandmother, my granddad had this done at a young age, teenage, twenties, thirties.

• 14:55Speaker 05

  All the teeth pulled. Paul McCartney's dad on Fresh Air, he mentioned the story about his dad when he said, "You should have them at 21. We'll take you in to get them all pulled. Get you some of them new fangled dentures." And so people would do that. And it's kind of sad because at the time, dentures, there were no implants like there are now. You can kind of click dentures into the implant and they stay put pretty well. But back then, that was not the case. You had like 25% of the chewing efficiency that you would have had if you had your normal teeth. So anyway.

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• 17:03Sean Carroll?

  Well, this is, so we got some stories on the table, so we can start drawing some lessons here. I mean, it seems that one of the lessons of your book is it's hard and maybe even harder than you think to replace body parts artificially. Is that fair to say?

• 17:17Speaker 05

  That is very fair to say. That it is so challenging. I, at one point, when I was working on this book, I thought, is there any bit or piece of the human body that we can really replicate such that the replica is as good or better than what we started out with? And I got very simple. I'm like, okay, tears. Let's do tears. And I found this guy who's entire career has been based on trying to create an artificial tear. And not specifically the tear that when you cry or when you cut onions, but the tear film, which is a protective and lubricating layer. And the tear film, okay, we spent the duration

• 18:00Speaker 05

  of two free zooms, what is that, 45 minutes plus 45 minutes, talking about the tear film and the miraculous structure that holds all these layers in place, the glycolics and how it helps with retaining moisture and how there's mucins that catch the glop and depositate, you know, that sleep snot in the morning, right in the corner of the eye. Those are the mucins at work. And it was, anyway, what all that leads us to is, we can't even, we can't even recreate.

• 18:32Sean Carroll?

  Not even that.

• 18:33Speaker 05

  Not even that. Not even that. Yeah. The only thing, I think, the transplant that I think works the best is one that I addressed in a, in a previous book, which is the fecal microbiome transplant. I think that's, that's a situation where the one that you have is, has been invaded. You've got, you know, C. diff running loose in your gut. And so take someone else's microbiome. And now it's all, they're encapsulated. But in the beginning, it was just, it actually started out as a veterinary technique. But, but, you know, going back to when gulp, when I was working on gulp, it was like a guy showing up at the medical center with a brown bag, saying, not my best work. Here you go, though. And

• 19:15Speaker 05

  that material being put in a blender, an oster blender, in fact. And

• 19:22Speaker 05

  Mixed with distilled water, I think it was. And then that was introduced into the colon with a colonoscope, which has a kind of a plunger attachment. And two days later, the guy is having normal bowel movements, which, you know, that was exciting. I mean, people die from C. diff and this guy in two days, I mean, he was overjoyed. So that's a pretty successful transplant, replacement.

• 19:46Sean Carroll?

  I mean,

• 19:47Speaker 05

  But we're not, we're not replacing healthy, normal. We're replacing compromised and invaded. Yeah.

• 19:54Sean Carroll?

  I kind of want to ask more about the fecal microbiome. I mean, what is, what is the role of that? What does that do? What is it?

• 20:03Speaker 05

  Oh, the fecal microbiome, that's just, that's all the bacteria that you have in your colon that are breaking down what you deliver by eating. So that's incredibly important. And a healthy microbiome does that without causing a lot of gastrointestinal distress. So people with, with C. diff, that's a bacteria that gets, I don't know how it gets in, but it gets in often in hospital settings. And it's really hard to eradicate with, I mean, you can, antibiotics sometimes do the trick, but when they don't, really hard to get rid of. The fecal microbiome transplant is a pretty amazing thing.

• 20:43Sean Carroll?

  Yeah, it is, I guess, a reminder from my perspective that biology is way more complicated than, I want to say physics, but just mechanics, right? Like a nose is just sitting there, letting the air come in. But in the more complicated biological cases, there's so many moving parts that even now, we're not very good at figuring out what they all need to be to have a successful replacement.

• 21:08Speaker 05

  Right, right, right. That's true. I mean, even something like a hip replacement, hip replacements, you know, they're at a point where, you know, fewer than 1% of Cases, there's a serious infection. But the first one was 1938 and they went through some rough times. There was, there was the big Teflon fiasco where the, you know, it's like a ball and cap. And the cap, they were trying to, you know, create the same kind of frictionless movement that exists in the human hip. And Teflon was a new substance and there was this guy, John Charley, who was like, hey, I've heard about this stuff and it's really great and the coefficient of friction is really low and let's try that.

• 21:53Speaker 05

  And so they started making the cap, you know, the acetabulum, the simulated, you know, cap in the hip where the ball of the femur goes. And it seemed great. And then what happened is it wore, it wore down really quickly and the body reacted to it poorly and this horrible cheesy substance, that's a technical term used by John Charlie, Charley, a cheesy substance. And it was a mess to clean it out and to redo these hips. It was horrible. There was that, then there was the metal on metal period where little bits of metal debris were setting up kind of an inflammatory reaction and that was horrible. So it's taken a while to get to the point that we're at now where like every other person in their eighties has a fake hip.

• 22:38Sean Carroll?

  I would have thought that-

• 22:39Speaker 05

  That's not, that's not an actual statistic.

• 22:41Sean Carroll?

  No, I was like-

• 22:42Speaker 05

  Yeah.

• 22:43Sean Carroll?

  I would have thought that any chef who was familiar with nonstick cookware could have told them the Teflon does not last very long.

• 22:49Speaker 05

  You would think, right? You would think.

• 22:52Sean Carroll?

  Maybe it wasn't too much back then.

• 22:54Speaker 05

  Yeah, I know. I saw a photograph of, you know, of one of these caps and it was just, you know, it was almost completely worn through, you know, it's just, just like a mess, yeah.

• 23:07Sean Carroll?

  But okay, the hip replacement is an example of what I was gonna guess or presume is the other successful genre, which is just limb replacements, right? I mean, they must've had prosthetic limbs of some sort way back in the olden times.

• 23:23Speaker 05

  Sure, sure, yeah, there were, you know, wooden legs, there was, there was, there was an aluminum leg that was quite exciting because it was lighter weight, this was in, in the UK, a lot of the military veterans were excited about the military light leg, because there, for a while, there was this belief that when you replaced a leg, the prosthetic limb should weigh the same as the norm, as the, you know, the remaining leg, which is actually, that's a pretty heavy leg, and so, people were dragging around a lot of weight, it was very uncomfortable, it was held up by harness, it was uncomfortable, so, now we're at a point where, artificial

• 24:03Speaker 05

  legs, mostly legs, are starting to be actually screwed into the bone, it's called osseointegration, and that's terrific, if it works, if you don't get an infection, because now you can, you have sensation of the floor, you can sort of feel the surface that you're walking on, you don't have to check to see if you're stepping on somebody's foot, you can move it, just, it's just far more like having a natural limb, but there, but it's, you have to close up the skin around it, it's not a complete seal, bacteria get in, so there've been issues with infection, there's a couple of different techniques, anyway,

• 24:44Speaker 05

  I, I'm, I would be, if I had an artificial leg, I'd be hopeful that they work the kinks out on that, because it sounds like a, a big improvement.

• 24:55Sean Carroll?

  And was there any feeling back in the day that like the dentures, we might actually improve ourselves by having an artificial limb, like maybe you have an arm that could be a hook, or a pommel, or a hammer, or whatever?

• 25:11Speaker 05

  I don't think anybody was lusting after a hook, but, but, one of the ways I got interested in this book was I met a woman. She actually emailed me about something else and we got to talking. She's a she's a amputee, lower below the knee amputee. She's an elective amputee. So she is someone she had a healthy foot. That is to say it had a blood supply. It wasn't wounded, but it was twisted. She'd had spina bifida and it was twisted. She'd had multiple operations. It just was underperforming and she would see people with below the knee prosthetics who were

• 25:51Speaker 05

  hiking and running and doing all these things that she herself couldn't really do. And she's she wanted to find a surgeon to to cut it off. It took her it took her quite a while to find somebody to cut off, you know, to cut off a quote unquote healthy limb because she said they'd say to her, look, this is a healthy foot. I can't cut it off. She goes, yeah, but I can't walk on it. And it took her a while to find somebody willing to do that. I mean, it's,

• 26:20Speaker 05

  you know, I guess if you're a surgeon, there is a kind of a worry. It is there's a finality to lopping off a foot, kind of can't not going to get it back. And I guess a fear of what if the patient now has some kind of chronic phantom pain, phantom limb pain, you know, what? It's just easier to go ahead and do another surgery and hope for the best.

• 26:40Sean Carroll?

  There are some runners who are amputees, right? You can get replacements that allow you to run fast. That's the limit of my knowledge right there.

• 26:49Speaker 05

  You can get replacements for hockey, for pool. They're called terminal attachments. So it's a it's a different kind of you put on a like a rock climbing attachment or a kayaking attachment or a ping pong attachment. Sometimes the piece of equipment is sort of built in. There was a prosthetist who built a mop foot for his wife, which is kind of weirdly sexist.

• 27:16Sean Carroll?

  That kind of is, yes. For his wife is the ceiling to deal with.

• 27:21Speaker 05

  Yes. Yeah, exactly. Yeah. So but interesting, you know, I talked to Ezra Freck, who was a

• 27:34Speaker 05

  He's a Paralympian. He won a couple of golds in the recent Paralympic Games. And it was funny, when I met him, I didn't know, I didn't know who he was. I was talking to his dad, who does a lot of work with recent amputees, trying to get them back into sports. And Ezra came up, and Ezra has an amputation at the thigh, and then he's got, I think it's, anyway, I said to him, "Can you run?" Like, this is, this guy is unbelievable. He's like a high jump medalist, a sprinter, you know,

• 28:13Speaker 05

  and I stupidly said, "Can you run?" Yeah, but, um, so yeah, there are definitely their attachments for running. I also said stupidly, like, I brought up that business about Oscar Pistorius, and did he have an advantage because he had that blade? Because people often think, "Oh, that's like techno doping." And Ezra said, "Well, first of all, he didn't, he didn't win." Like I had said, he didn't win, he placed, whatever. And he said, "He's the first, it's the first time somebody with an amputation has, has made it that far. Nobody has since." If it were an advantage, we'd be seeing amputees in the Olympics all the time.

• 28:54Speaker 05

  So, but, but anyway, interesting, it was an interesting day there at the Amputee Coalition Conference.

• 29:01Sean Carroll?

  You've already mentioned the weight issue in the limbs. How, what other kinds of improvements have there been? Like, can we hook up nerves in our body to manipulate the limbs at all?

• 29:16Speaker 05

  Well, what, this tends, that kind of stuff happens in developing, there's a lot of effort now to develop arms, lower arms and hands with articulating fingers, so that you can grip things. And so it's, you know, when you think to your, you think, "I want to close my hand", you have that thought, you're sending an impulse. And the impulse, if you amplify that impulse, and a computer kind of translates that, then you, you know, you can move the hand. The ones that I'm, that, as far as I know, they're kind of toggling through different grips. It's not, it, it's slow, you know, it's, I mean, the-

• 30:04Speaker 05

  I read an essay by Britt Young, who writes a lot about this. And she pointed out that, first of all, they're very heavy. Those kind of bionic-looking limbs are very heavy. They need to be charged. They're very expensive and can be exhausting mentally to use. It's not, it's not the same as just, you know, me reaching over and picking up my glass like that. I was walking around the amputee coalition with this woman who had the foot amputation. And we passed a booth. I only saw one booth for arms that whole day. And it was that, you know, that classic shot of the kind of Arnold Schwarzenegger bionic-looking

• 30:47Speaker 05

  limb, and it's holding a raspberry. And she, she laughed. She goes, "Are you gonna spend like 30 seconds of getting your grip right?" No, you're gonna reach over with your other hand and pick it up and eat it. So it's that kind of thing. Not to say, I mean, eventually, I would imagine eventually, these things will become lighter, faster, more practical, cheaper. But they're not there yet.

• 31:15Sean Carroll?

  It does seem that even for robots, it's difficult to get them to like pick up an egg or whatever, all this fine-scale stuff.

• 31:21Speaker 05

  You know, my, my favorite kind of, I don't watch a lot of videos on YouTube, but my favorite are the, you know, the soccer-playing robots that fall over.

• 31:32Sean Carroll?

  But they're getting better, like you said. Like, I wouldn't want to play against them 20 years from now.

• 31:37Speaker 05

  I know, I don't want them to get better because they're really entertaining when they fall over each other.

• 31:43Sean Carroll?

  So, okay, so, but mostly, yeah, so these are the obvious ones. You lose a nose, you lose a, you lose a limb. How good are we getting at replicating like functions of organs in the body? Obviously, there's artificial hearts. That's probably the biggest success story, I guess.

• 32:00Speaker 05

  Right. Well, in terms of transplantation, xenotransplantation has been a pretty cool thing to follow this past couple of years. It's just now seems to be getting to the point where...

• 32:15Speaker 05

  Patients with, say, a pig kidney, it's mostly kidneys, are making it longer than two months. There was a whole slew of hearts and pig hearts and pig kidneys going in to patients who lived about two months. Wow. But there's a man now, Tim Andrews, I think it's going on eight months, and eGenesis is just starting a trial with, I don't know how many patients getting pig kidneys, a dozen, maybe. Anyway, so it's, and Tim Andrews is in much better shape. The early recipients were getting these organs under compassionate use exemption, because these organs would have to be FDA-approved. Yeah.

• 32:57Speaker 05

  And they're not, they're not yet. But these were folks who were so close to being deceased that it was felt that, you know, this might, they're not going to make it anyway, so let's give them a chance and let's advance the research. So they were pretty sick. So those are the folks who are lasting two months. Tim Andrews is in, was in, is in better shape. So that's promising, you know. And eight months is, that could be enough time for a patient to make their way up the donor list, you know, and become eligible for, then for a human organ. So it's, right now, thought of kind of as a, a bridge, you know, a stopgap.

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• 34:09Sean Carroll?

  Do we understand very well what puts that time limit on it? Is it just that, I mean, obviously, at the cellular level, pigs and human beings are different, but is that translatable into a specific reason why it doesn't stick?

• 34:24Speaker 05

  Um, there have been different reasons. There have been a couple cases of viruses, pig viruses, that actually affect humans. So there were some zoonoses, as they say, causing a problem, a pig virus. There was another case where the heart, heart started growing, outgrowing the space that it was in, and that was causing a problem. Kind of like the Grinch, remember the end of the Grinch where his heart grows two sizes? But in the Grinch, it's a happy thing. But in this case, it was, it was a problem. So, and you know, there, there's still a tremendous difference between, even if you, basically,

• 35:07Speaker 05

  they're knocking out this alpha-gal protein, which is a surface protein that makes the body kind of go like, red alarm, this is not normal, and attack it. Like, it's a, it's called a hyperacute reaction, and it kills the thing, turns black, starts turning black right away, just like, out of there. The body does not want this. So they've knocked that out, now you're at a level where the same kind of immunosuppression that you would give a patient who's receiving a human organ, that, you know, it's still, there's still immunosuppression. But I talk, you know, I spent some time in, in China for this chapter, and this researcher who's been working on zeno-transplantation for 30 years, I said, you know, you, could

• 35:50Speaker 05

  you eventually edit the pigs to the point where these were the kind of match that didn't even require immunosuppression? And he's like, nah, no, but he, but he said, you know, but what you could do, you could sort of tweak it so that the organ was secreting a localized immunosuppression, so you didn't have to give systemic immunosuppression. So he had all these ideas, and he was very hopeful for the future of pig organs in humans.

• 36:19Sean Carroll?

  Is there a good reason why it's pigs in particular that we use to replace human organs?

• 36:24Speaker 05

  Oh, that's a fine question, and I looked into that.

• 36:30Speaker 05

  You can kind of blame it on the Hormel Corporation. Because I was curious, like, why pigs? Why for medical and surgical experimentation? It's been pigs for a long time. And pigs are big and loud, though. There was this great quote by Pavlov, who preferred dogs. He said, "All pigs are hysterical." Like, you bring them in, and they're squealing really loud. I've seen this in a lab setting. A pig is a big animal, and they're very loud, anyway.

• 37:13Speaker 05

  Back in the, god, 40s and 50s, it was a collaboration between the Mayo Foundation, which is the research arm of the Mayo Clinic, and the Hormel Institute, which is the research arm of pork. Those two got together and bred pigs smaller. They bred them smaller so that they'd be easier to have around the lab. The organs would match ours. They also did all of this experimentation on comparing the coronary arteries of pigs to humans, like, trying to see, like, how close are they? And pigs are, in fact, someone described them, pigs, as a caricature of an obese human,

• 37:57Speaker 05

  because they get coronary artery disease, they don't get a lot of exercise. This is, you know, domesticated pigs. They eat garbage. So they're kind of perfect for that work. And they were, like, every, kind of, they went into every possible application. There was a, I remember seeing a paper...

• 38:23Speaker 05

  On orthodonture and were pigs useful for studying orthodonture? There's a they put, somebody put braces.

• 38:32Sean Carroll?

  Wow.

• 38:33Speaker 05

  On a pig, braces on a pig. Anyway, so poor pigs, they, you know, that it just that pushed everything down that road. And once that started and things began to be known about pig coronary arteries and pig kidney function and pig liver function and pig teeth, you know, they, a lot was known. And so it became kind of the go to animal.

• 38:55Sean Carroll?

  Well, and yeah, I guess the, the point is that once you start down that road, you know a lot more about the pig than you do about other options. So if you're a person.

• 39:03Speaker 05

  Right.

• 39:04Sean Carroll?

  Who's going to get something put in them, let's go with something we know something about.

• 39:08Speaker 05

  Yeah, that's right. That's right. And they are, you know, similar, similar size and fairly, in some cases, fairly similar functions as the Hormel Institute helped us learn.

• 39:21Sean Carroll?

  And, and what is the process like for just figuring out whether these crazy ideas of replacing a human interior organ with an animal's interior organ has any chance of working? Like, what is it like to be the first person to get a liver from a different kind of animal? Is it, is it basically like it, it happens with people who are near death anyway? Or is it something more expansive?

• 39:44Speaker 05

  Yeah, uh, yeah, that tends to be the, the first, the first one. I, I didn't, I'm sorry, I didn't, um, I didn't speak to the first, um, Mr. Bennett, I believe his name was, who, uh, the guy who got the first pig heart, I believe it was. But I spoke to the surgeon, um, Dr. Mohayeen, I'm probably mispronouncing it, uh, Mohayeen, anyway. And he's, he said that Mr. Bennett said. Had a concern, although not all that serious. He said, "Am I going to be going oink, oink after this?" Like this could, you know, that concern that sometimes people who get a new

• 40:26Speaker 05

  heart have this belief, this sense that they have changed in a way, that they have taken on characteristics of the person who donated the organ.

• 40:37Sean Carroll?

  Well, the heart is sort of in literary ways of thinking about the human anatomy. It's the seat of something. And yeah, we know it's just a pump blood, but it means something to the person who has it.

• 40:49Speaker 05

  It does. Yeah. You don't hear that from people getting kidneys, that they feel like they've taken on traits of the donor.

• 40:58Sean Carroll?

  And I guess, yeah, for like hearts and lungs and whatever, a couple of months, that's a sobering fact. But for smaller things, I get the impression that, you know, you can replace the valve in a heart with a pig valve and that would last longer. Is that right?

• 41:12Speaker 05

  That, yes, absolutely. Yeah. I mean, eventually they need to be replaced, but the pig valve, yeah, the pig valves last, I don't know, a decade, is it? I'm just throwing that out there. I knew someone who had a pig valve. Yeah. And it's, yeah, go ahead, go ahead.

• 41:30Sean Carroll?

  But we also just do purely mechanical ones. I mean, what's the, what's, do you know the trade offs between saying, okay, you need a new body part, heart or just a valve? Do you want the pig heart or do you want the completely artificial one?

• 41:45Speaker 05

  I don't, I don't, I don't think, again, I think that the artificial heart is again a stopgap. You don't, you don't meet people who have a artificial heart for very long. I don't think. I didn't, I didn't report on artificial hearts, but the sense that I got was that they were a temporary measure while somebody awaits a heart from a, from a donor. Yeah.

• 42:13Sean Carroll?

  Are we, this is not exactly what you were talking about in the book, but how good are we at just, you know, replacing human parts with human parts? Like, is the technology for human organ donation pretty good these days?

• 42:26Speaker 05

  Yeah, there's a couple of things going on that are pretty cool. I spent some time at the University of Michigan has a lab called the extracorporeal life support lab. And it's all about devices that do the job of parts of the body outside the body extracorporeally. Right, yeah. And yeah, so when I was there, when I was visiting, they were trying to, they were working toward creating, or working toward figuring out, how can we keep these hearts that we have taken out of someone's body for transplantation? How can we extend the shelf life?

• 43:10Speaker 05

  Because right now, you know, if you just put them on ice in a cooler and you send them off, you've got, you know, four, six hours, something like that. There are perfusion machines that will sort of oxygenate the heart in kind of, it's called a heart in a box. That'll take you to, I don't know, eight or 12 hours. What they were trying to do is figure out, how can we extend that to 24 or 48 hours? Because that would allow you to test that organ, see how well it's functioning. So, because right, and now there's an age cutoff and a lot of hearts get dumped because they're too old, but they may be working well. Maybe the person was a marathon runner, but they, there's a cutoff. So if you could test the heart and see how well it works and have that be the criterion

• 43:54Speaker 05

  by which you decide, does this go into another person? You could also work on it. You could fix it. Yeah. You could, I don't know, put in a, clean it up. Yeah, exactly. Kind of like a, you know, reconditioned iPad or whatever, the, the, those ones that I always think I should get and I don't. Yeah, so, you know, they were, they were testing, you know, if we change, if we alter the flow, the blood flow through this heart, because right now they pump a lot through because they want, you know, the thinking being more oxygen is better. So they're, you know, it's a high flow rate, but that damages the valves pretty quickly. They, they start to get leaky, things start to deteriorate.

• 44:38Speaker 05

  So they were testing a lower flow rate that day and it was. Really cool because there's this heart and it's attached to this gizmo. You know, first they remove it from a pig that has been, of course, completely sedated. And they take it in the other room and here's this first, but amazing thing. First you have to stop it. Like a heart will keep on beating for up to 10 minutes outside of body.

• 45:01Sean Carroll?

  Okay.

• 45:02Speaker 05

  Maybe you knew that.

• 45:03Sean Carroll?

  I did not, no.

• 45:05Speaker 05

  That, um, yeah, even the, the, uh, the research fellow who was doing the work sent me a video later of a heart because he had said, yeah, like sometimes I have to take a sample for pathology and it's still beating. The heart is still beating and I'm trying to take a very thin slice and it's very annoying for me.

• 45:26Speaker 05

  It's very annoying for me. He sent me an image.

• 45:31Speaker 05

  Um, a little video of a heart on a blue surgical cloth separated from a body. And it's been cut in half, kind of like a deli roll and it's still beating. It's still beating. It's just the weirdest thing. Anyway, hearts.

• 45:47Sean Carroll?

  I guess this, this just shows my ignorance. I had assumed that those heartbeats were triggered by signals from our central nervous system.

• 45:56Speaker 05

  Well, they have a, an internal, um, uh, kind of, um, electrical system.

• 46:02Sean Carroll?

  Yeah, okay.

• 46:03Speaker 05

  And I, I, and I used to know the term for that. It is in my book and like so much. Look, these are flashcards. This is me trying to remember what's in my book.

• 46:15Sean Carroll?

  Let's give the audience a reason to buy the book. That's okay.

• 46:20Speaker 05

  Yes, that word, the term is in there. It'll, it'll probably occur to me in about three minutes and I'll blurt it out, derailing whatever we're saying.

• 46:28Sean Carroll?

  I mean, I guess I'm occasionally really amazed that our organs last so many decades at all. You know, we're much better designed than most machines are, right?

• 46:42Speaker 05

  Yeah, no, I know. You see, you know, I remember the first time I saw. A heart beating. It was a, a, um, an organ recovery. So this person was, uh, brain dead, like legally dead, but being oxygenated on a ventilator. And they open up the body cavity to take out the heart and you see this thing and it is just squirming around like a stot in a burrow, just like it's really active. It's just, it's, you know, you feel your heartbeat and it's sort of a gentle, kind of gentle, I don't know, mild.

• 47:15Sean Carroll?

  Yeah, calm, mellow.

• 47:16Speaker 05

  Motion. And you see this thing and it's just like, I don't know, I can't, I can't, I can't put words to it, but, uh, and it does that for, you know, my mother-in-law is 101. That thing's been going for 101 years with no sign of slowing down. It's unbelievable. It's just, it's just crazy. I remember seeing at, um, it was a bioprinting lab and they were showing me their cardiomyocytes, heart muscle, cells, and it's just a layer of cells and they're all beating in tandem. They're not, they're not a part of a heart. They're just, they're, they're, they're all like, it's like a stadium wave. They're all doing their thing

• 47:56Speaker 05

  just like, and it's sometimes, the researcher said, sometimes they get going so, so kind of vehemently that they, they catch air, like they come right up off the bottom of the slot. It's unbelievable. Like they, that like they apparently one cell will open up a little, you know, kind of like start communicating with the cell next to it and then the next one. And soon they're all just like beating in tandem.

• 48:19Sean Carroll?

  They're dedicated to the task. I gotta admire it a little bit.

• 48:22Speaker 05

  They are, they really are.

• 48:25Sean Carroll?

  You, you mentioned briefly a cutoff for organ donations. Is that like a universal number or is it dependent on the organ?

• 48:34Speaker 05

  Probably depends on the organ. I'm not sure, but.

• 48:36Sean Carroll?

  I just want to know, am I past the limit? Am I, my organs all sort of useless by now?

• 48:40Speaker 05

  I don't think so. No, I don't think so. No, I think you're good to go.

• 48:46Sean Carroll?

  And, and just, just briefly, I guess, what else, what else are we good at in terms of, um, replacing organs, uh, besides hearts? We got livers.

• 48:54Speaker 05

  Oh, we are really good at, uh, the lens of the eye.

• 49:00Speaker 05

  Is very, I mean, that's a, uh, yeah, the people are now getting both of them done at once. You go in and a couple hours later, you come home and now, and now you can see clearer, better. And depending on what kind of lenses you get, you have a little bit of accommodation. We haven't figured out yet how to mimic the incredible autofocus of the human eye where you go from reading to distance, especially as a teenager in my age, not so much. But that is yet to come. There's been a bunch of techniques and multiple lenses and fluids and people sticking various things in there, trying to mimic accommodation.

• 49:44Speaker 05

  But just a simple, uh, single focus lens is pretty, it's pretty amazing how quickly that can be done. And it's, you know, it goes in, it's got a little plunger, almost like a tampon. You know, tampon.

• 49:57Sean Carroll?

  You've written books about these things.

• 50:00Speaker 05

  A planet. And it, yeah, so the lens goes in and it's folded up like a hard taco shell. And then when it's in it unfolds. And so the incision can be much smaller. You don't need, uh, you need stitches back in the early days of cataract surgery.

• 50:16Sean Carroll?

  So this is, yeah, I was gonna say, this is for cataracts. It's not just because my eyesight is failing. It's a little bit more serious than that.

• 50:23Speaker 05

  Well, it's gotten, the technique has gotten so reliable and so safe that there are folks who are simply myop, you know, they're, they're nearsighted like me, and I can barely read the big E. And, and they are getting a lens, rather than get Lasik, they are getting a lens implanted. So there's not that, yeah.

• 50:46Sean Carroll?

  That's the one surgery that I've had to change my body in some way. I did have Lasik and it's a

• 50:50Speaker 05

  Oh, you did?

• 50:51Sean Carroll?

  I did. Yeah. Oh, I mean, I, I'm a huge fan of, of doing it well. And they can't fix, like you say, the autofocus, they can't fix it so that you can do, you know, they can't fix both nearsighted and far sighted at the same time. So they do your two eyes slightly differently. Uh, one is good at close and one is good at far. And the brain figures it out. It's, it's sort of completely natural.

• 51:14Speaker 05

  Yeah, yeah. I had that with my contacts for a while. I had one. A slightly stronger prescription, yeah.

• 51:21Sean Carroll?

  But the downside is that you smell your eyes burning while they're firing lasers into them, and it's a little disconcerting.

• 51:29Speaker 05

  Oh, really? Wow. Yeah, does that smell like burning flesh? Because I've been in surgical procedures where that smell, you know, I'm kind of like, does that smell good? I don't know, like burning flesh.

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• 53:15Sean Carroll?

  I am personally not sufficiently acquainted with the smell of burning flesh to tell you whether that is true or not, but it smells like something is burning. They, they offer you a pill if you want to like be calm, right? If you don't want to, don't want to face up to the, your eyeballs being lasered, but.

• 53:33Speaker 05

  And did you get a lot of halos and kind of aberrations of night vision?

• 53:39Sean Carroll?

  Yeah, I mean, fortunately, I was living in LA at the time and they have very, very good, you know, surgeons of this sort. So, no, like that first day, your eyes feel all weird. The next morning you wake up and it's fine. That's it.

• 53:52Speaker 05

  Wow. Are you very nearsighted like me?

• 53:54Sean Carroll?

  I was pretty darn nearsighted. Yeah.

• 53:56Speaker 05

  Yeah. Yeah. Okay.

• 53:58Sean Carroll?

  And it's like, that was like 10 years ago. I'm sure I'm going to, you know, it's going to fade away. It's not quite as good as it was, but a lot better than putting contacts every morning.

• 54:06Speaker 05

  Yeah, I just, I hate reading glasses, so I, I like to be able to take off my contacts and read. I just, I have to hold the book like three inches from my face, but, but I like, you know, I have kind of microscopic vision. Anyway.

• 54:22Sean Carroll?

  Anyway.

• 54:23Speaker 05

  Anyway, yeah.

• 54:24Sean Carroll?

  Just going through the list of fun things that we are replacing, these, these body parts that we're replacing, like you mentioned the skin moved around with the nose right at the start, but replacing skin is also something that is a big, is a well-known thing, right?

• 54:43Speaker 05

  Yeah, yes. Skin grafts, skin is a, skin grafting for, for severe burns. It's an interesting area in that there, there were the, there was a period of time when animals were recruited for this, often chickens and frogs. I think partly because the, you know, the chicken has that loose skin under the flaps and it's sort of like easy to kind of take it off and install it. So it's a lot of popular press stories about people being part frog and part human. But in fact, with a serious third degree burn, one of the most

• 55:24Speaker 05

  dangerous things is that your immune system is suppressed for a while. And so infection, people often, if, if they're going to die early on, it's from infection, from sepsis. But the other side of that is that the body is very. Nonchalant about taking on a piece of frog skin, or chicken skin, or puppy skin, or whatever it is. It's uh, and it will uh, it will kind of, for a few weeks, it'll, it'll kind of take and it'll sit there and it's a very good covering. Eventually, the body rejects it, it sloughs off, or the surgeon, in the case of cadaver skin, or whatever's been put on, they'll peel it off and they wanna, they want it to bleed, they want it, that freshen is the term.

• 56:08Sean Carroll?

  Okay.

• 56:08Speaker 05

  Uh, because now they're gonna install the permanent graft, which is uh, the patient's own skin. So ultimately, you want skin from, so that you don't have to use immunosuppression.

• 56:22Sean Carroll?

  So from one part of your body to another one?

• 56:24Speaker 05

  Yeah, yeah, exactly. Um, but with a really serious burn, sometimes there, you know, there's not much real estate left.

• 56:32Sean Carroll?

  Right.

• 56:33Speaker 05

  You know, and it's uh, and then they'll end up using the same, using it uh, like a patch on the leg, say, and then waiting for that to heal and then using again, it's using it again. It's a long process. It's a, yeah, there, there are some great new developments, like um, there's something called CEA, cultured epithelial autograft, and this is where you take the patient's own skin, uh, and it's sent off site and the um, patient's skin cells are um, grown out into a very, very thin patch. So it's, it's, you're creating a graft of their own skin, which is helpful if the patient doesn't

• 57:15Speaker 05

  have a lot of unburned real estate to work with. There's also spray-on skin, similarly, that's like, you know, you could uh, sometimes cadaver skin is meshed to kind of feed it through sort of, looks like a pasta maker. So it's, it creates this mesh, so you can stretch it out and cover the wound and, and then the spray-on skin would be used to fill in the little. Holes in the mesh. So I think a company, Cutis, is working on full thickness skin that it grown from the patients. That is not yet approved. It's it's still in the early stages.

• 57:54Speaker 05

  But I saw a kid at, I was at Mass General, the Sumner M. Redstone Burn Center. And there was a boy who'd been burned on more than 80% of his body. And he was getting, yeah, he was going to get some of the, they were growing some of his cells. They're sending his biopsy to Switzerland, to this company, Cutis. And they were, they were like escorting the new skin back and going to install it in this, in this little boy. Again, a compassionate care exemption. So

• 58:29Sean Carroll?

  And will that

• 58:30Speaker 05

  So, yeah.

• 58:31Sean Carroll?

  Will that new skin have the same properties ideally as the old skin? Will it have the sense of touch?

• 58:37Speaker 05

  Sure. It should, sure. Yeah, it should. Yeah.

• 58:41Sean Carroll?

  How surprised should we be that the human body is not better at just regrowing things? You know, we last forever. But if you lose a finger, we don't have the ability to just, you know, the body can't regrow it. Some animals can, I guess, right?

• 58:56Speaker 05

  I know. Our livers, we can regrow our liver. We can regrow, yeah, I mean, you can regrow skin. I mean, if you, first and second degree burn fills itself in from below, you know, it's just gonna like eventually grows

• 59:11Sean Carroll?

  Yeah.

• 59:12Speaker 05

  A new layer. Third degree is tough because that you lose that ability. And so the body tries to close up the hole by contracting, like a drawstring effect.

• 59:21Sean Carroll?

  Yeah.

• 59:21Speaker 05

  And then you have those terrible disfiguring, you know, the jaw pulled down to the collarbone or an eye that won't close, that kind of thing. But, but first and secondary, second degree burn, the body is pretty good about regenerating. But yeah, why, why can't we regrow everything? I don't know. Ask, ask God.

• 59:41Sean Carroll?

  God has a sense of humor here. But I mean, there must be some med scientists out there who are trying.

• 59:50Speaker 05

  To re, I'm sure that there, there are people studying, you know, salamanders or whatever creatures. And that's why, that's why I think it's so, it's so important, basic science, basic understanding of, of animals and lizards and creatures that have these different abilities. If you can sort of tease that apart and see what's going on, maybe there's a way to mimic that or prompt that in, in humans. And so that's the kind of thing where people go like, they're doing a study on this salamander, what a waste of money. It's like, no.

• 1:00:28Sean Carroll?

  Yeah.

• 1:00:28Speaker 05

  No, it's not.

• 1:00:30Sean Carroll?

  I don't know if you've ever run into Michael Levin at Tufts. He was a former Mindscape guest and he is, he's studying exactly these things. Like, how do different animals at all different levels sort of encode the plan into not just their DNA, but you know, all like, there's things, you try to move an organ from one place to another and the body just moves it back.

• 1:00:51Speaker 05

  Mm hmm. Yeah, yeah, yeah, yeah. That's interesting. But you can also, you can also install things in a body in a different place and it works just fine. You can take, you know, islet cells, you don't have to put them by the pancreas. You could stick the islet cells under the skin, you can, you know, which was great because it's easier to access. You don't have to go in for surgery. So if you, you know, if you're talking about however you've either grown them or they're transplanted or whatever, some people are looking at, they're parking them all over the body. They don't have to, they don't have to be at the, on the pancreas.

• 1:01:25Sean Carroll?

  And yet, like, we're still not very good at hair, right? We can't, you know, people go bald and we don't know how to really fix it.

• 1:01:32Speaker 05

  I, I, I know. Yeah. Hair, you can get a hair transplant, but man, that is an all day job. That you can transplant two kidneys in the time it takes to do a hair transplant. Yeah, that's a, okay. Yeah. Cause you gotta go, first of all, you gotta like pull them all out and then you gotta stick them all in. And that's a, it's, it's like one follicular unit at a time. So that's a lot of. It's a lot of work. And then, you know, you've got this row, you know, bringing your hairline down, but then you keep losing hair. And now you've got the bare strand behind. So you've got to go back and get more. And eventually you run out because the sides and back are starting to get sparse.

• 1:02:12Sean Carroll?

  Well, I was gonna say, like, how successful is it? When you get a hair transplant, does it last forever? Or is it one of these things, just like everything else, where the body starts rejecting it?

• 1:02:21Speaker 05

  No, I think, no, hair transplant, it's your own, it's your own stuff. So, yeah, no, I think it works quite well. I mean, ask Elon. I don't know.

• 1:02:30Sean Carroll?

  It looks okay. You can afford it.

• 1:02:32Speaker 05

  Yeah, it's just that it's a, it's a lifetime commitment because you're, as the hairline continues to recede, you need to keep, you need to keep having it done. Or you could do, I don't think it's even possible to get this done in Turkey anymore, but in the 70s, there was artificial hair transplantations, essentially like doll hair that was being installed with a little surgical crochet hook, kind of, I mean, not a good solution, though. Because, no, no, you know, because you can't really style doll hair and it won't go gray. You start to go gray and it's still red or whatever, but, and they got infected and anyway, but, yeah.

• 1:03:15Sean Carroll?

  We're learning. It's, it's just an example to me of like how even the easiest things are a little challenging.

• 1:03:21Speaker 05

  Well, yeah, I, yeah, I spent time at a biotech startup that, they were trying to create follicles. So taking somebody's blood, regressing it to pluripotency, right? So you've got these cells that you can then instruct to what you want them to become. So they were regressing blood cells to pluripotency. So then they're instructing them to become the building blocks of follicles. These two types of cells, keratinocytes and dermal papillae cells, which kind of do this amazing thing where they get together and they form kind of a primitive follicle, right? And the follicle, it did start creating hair

• 1:04:06Speaker 05

  material. But it wasn't growing up out of the skin. It was just sort of a black blob right under the skin. And they called it disorganized hair. So it wasn't the kind of thing you'd show investors and go, look, look, we've grown hair blobs under the skin of this mouse. So they came in and then they they're like, OK, we've got to give it a little tube so it could come up out of the skin. So they created these little, it was like a Barbie comb, these little rows of tubes that they were going to implant, kind of like a rice paddy kind of thing. But the tubes ended up being thicker than the skin of the mouse. They were and they were too, they were too delicate to implant, like in the way that anybody would ever be able to do.

• 1:04:49Speaker 05

  So then they tried putting the two types of cells on a piece of very thin thread that the thread would be implanted. This took years and finally they ran out of money and now they're out of business. And I went to them thinking, OK, follicle, how hard could that be? Yeah, really hard is the answer, really hard.

• 1:05:13Sean Carroll?

  Well, I have to give you a chance to talk about, and you have different chapters in the book where you mentioned, you know, for both men and women, attempts to regrow or replace our unmentionable bits that, of course, are going to be very, very important to someone. How how successful is that?

• 1:05:29Speaker 05

  Well, I I reported on two very specific types of procedures. One of them, one of them is unorthodox. It's not, it's not done anywhere outside of Tbilisi in former Soviet Georgia, as far as I know. I was curious about it. Yes, I mean, any opportunity to head off to somewhere I haven't been. But this was a surgeon who, in reconstructing, it was a man who had had cancer. And the reconstruction of this man's penis was not done in a conventional way, which would involve often flesh from under the forearm or some hairless part of the body

• 1:06:11Speaker 05

  and then surgical implants that you buy from whatever prosthetic company, you know, one per rectile chamber. And he chose instead to use for rigidity the man's own middle finger.

• 1:06:28Sean Carroll?

  Which was still attached to the, I mean.

• 1:06:30Speaker 05

  So, and I envisioned the finger being taken and installed, you know, as is with a nail and everything and able to move and beckon and the,

• 1:06:43Speaker 05

  which seemed pretty cool, sort of. But, but no, he was, he was wrapping it in a graft taken from the person's forearm, the underside of the forearm. And so it went, but, but it did have the function of it bent. There was, you know, that middle knuckle. The penis could be bent upward. I saw a slide. I never met this guy. He didn't answer my emails in Russian and Georgian and English. So I just showed up. Unfortunately, his office manager was like, come with me. We will go in his office. He's on vacation. I will show you slides.

• 1:07:21Speaker 05

  So I saw, I did see an image of the penis kind of with the mid, bent at the midsection with a ceramic water pitcher hanging off of it. I don't, and I wasn't ever really clear on.

• 1:07:42Sean Carroll?

  What that is about.

• 1:07:43Speaker 05

  I said, is that, is that similar to, because there are malleable penile implants that, and they, you know, it's sort of a Gumby thing. You can put it in position upward or you can bend it down out of the way. And she said, yes, so he can wear trousers. So it was a more of a fold it out of the way. So it's not poking straight out.

• 1:08:01Sean Carroll?

  Because this is now going to have bones in it, unlike the typical penis.

• 1:08:07Speaker 05

  I know. Yeah.

• 1:08:08Sean Carroll?

  Okay, just to, just to be sure, I understood the process.

• 1:08:11Speaker 05

  Yes, it is. Yes, it, yes, it's, it's going to have bones in it. So it would be the very first human baculum.

• 1:08:18Sean Carroll?

  But this is, okay, it sounds like from this particular story that there is no like agreed upon successful procedure for these circumstances.

• 1:08:25Speaker 05

  Oh, no, there, no, there, there is a standard procedure for, well, it for erectile dysfunction. You kind of take these implants, which look like. You know, they're the width of pencils and you stick one in each erectile chamber and they're inflatable. Uh, there's a little pump that in the scrotum that you squeeze when you want rigidity. So you, you squeeze that, pump it up and then you can, you know, let the air out. Or there's the malleable, the Gumby limb kind where you can, you know, bend it up or bend it down. So, um, but that's erectile for erectile dysfunction. For reconstruction, I would, you know, there, you would have the same kind of using skin from another part of the body.

• 1:09:09Speaker 05

  And then there'd be something in there for rigidity. I would think the same kind of implant that's used in erectile dysfunction. But, um, I don't know. Uh, he, he's the only surgeon who's doing.

• 1:09:23Sean Carroll?

  Who says romance is dead? I think this is, good to know.

• 1:09:27Speaker 05

  The guy, yeah, yeah. Then the, the office manager said, um, that he was in his sixties and she was in her thirties. And he said, she's very happy. Okay, good.

• 1:09:38Sean Carroll?

  Good, that's the testimony you need. All right. So, you know, we're, we're nearing the end of the, uh, podcast. We, we, we can be a little bit more expansive. I mean, I know you, you said very clearly in the book that you're not trying to predict the future. You're trying to explain what is going on now, but maybe a little predicting of the future is okay. I mean, we are getting much better at synthetic biology, at designer genes, things like that. I mean, do you think that replacing human organs is going to see a, a leap forward that is pretty dramatic pretty soon? Or is it just one of those things where it's so hard? We should expect progress to be very incremental.

• 1:10:16Speaker 05

  No, I, I think, well, it depends on how you define very soon. Um, spending time at, um, that bioprinting lab, uh, um, Adam Feinberg's lab at Carnegie Mellon, he kept, he kept saying, this is going to happen really soon. You know, and then it turned out what he meant by really soon was two to three decades. So for science, that is soon. That's soon, two to three decades. But, you know, so much is happening with, with AI and with, um, stem cell research and there's.

• 1:10:51Speaker 05

  It's both really slow and incredibly fast. Do you know what I mean?

• 1:10:55Sean Carroll?

  Yeah.

• 1:10:55Speaker 05

  Yeah. So.

• 1:10:56Sean Carroll?

  And the dream is someday we'll just 3D print a new limb or pancreas or whatever.

• 1:11:03Speaker 05

  Right. Yeah. Or grow it from scratch.

• 1:11:06Sean Carroll?

  Grow it from scratch. Okay. So there'll be room in a couple of decades for you to write a new book about this.

• 1:11:12Speaker 05

  No, you write this one.

• 1:11:15Sean Carroll?

  Maybe. Well, we'll see about that. All right. But Mary Roach, thanks very much for being on the Mindscape Podcast.

• 1:11:20Speaker 05

  Oh, my pleasure. Thanks, Sean.

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