How did syphilis get to Europe?

0:00 Howdy, extraordinaries. Today, we're talking about the history of syphilis. Where do we think it came from? How do we study it, et cetera? I'm not gonna get into some of the more difficult to hear about symptoms of the infection, but we are talking about a sexually transmitted infection. So if kids are around, well, you decide if that's a good idea or not. In 1530, Giralamo Fracastruro, a physician in Verona, publishes a poem in Latin called Syphilis Sive Morbis Gallicus, or Syphilis or the French Disease. It begins by discussing the symptoms of a deadly disease that was totally new to Europe and then shared best practices on how to treat it. The book ends with the story of a shepherd who offended the god Apollo, who rained

0:51 the horrible new disease down upon humanity as punishment. The shepherd was named Syphilis. And thankfully, Apollo eventually forgives him. Upon receiving forgiveness, a tree appears, which can be used to treat his affliction, and a helpful nymph appears to tell him that mercury can be used as treatment as well.

1:09 Not so helpful, really. But anyway, nearly 200 years later, a medical book gives the shepherd's name to the disease. It doesn't become common usage until about the 19th century, but syphilis is the name we use to refer to this infection today. On today's show... We're going to be talking about the arrival of syphilis on the European continent in 1493 and what we know or what we don't know about where it came from. Welcome to Daniel and Kelly's Infectious Universe.

1:50 Hi, I'm Daniel. I'm a particle physicist who's really interested in aliens, including alien diseases.

1:55 Hello, I'm Kelly Wienersmith. I study parasites in space and I'm interested in all diseases, you know, alien or earthbound.

2:05 So my question for you today, this morning, Kelly, is did you ever want to be a doctor? Lots of my friends in biology started out as pre-meds. I was wondering, were you on that track?

2:15 Yeah. When I was a kid, I used to love watching the show ER. I was like obsessed. And so I wanted to be an emergency room surgeon.

2:22 Who was your favorite?

2:24 I don't know. I really liked... You know, Dr. Green, Noah Wiley. Like, I don't know. There were so many. Oh, Luca.

2:29 Oh, Luca.

2:30 Anyway, there were a lot of, let's say, good characters in that show.

2:36 People to look up to.

2:38 Yeah. Nurse Abby. She was awesome. Anyway, lots of people to look up to. And then I decided I wanted to go to vet school. And then I decided I wanted to be a scientist. So long journey. What about you? You never wanted to be a doctor.

2:49 I never wanted to be a doctor because I didn't want the responsibility. I thought it was crazy. That if you didn't get enough sleep, like somebody's life was at risk, you know, and, you know, these days, if I don't get enough sleep, like a calculation happens more slowly or a factor of two creeps in or something, you know, bugs are harder to find. Nobody dies. So I like the irrelevance of my research sometimes.

3:12 That's exactly why I decided I didn't want to be an ER surgeon, because I didn't want to have to be the one to say, like, hey, I'm sorry your child died or like, heaven forbid, it was my fault. I was like, that's I can't handle that. I mean, thank goodness there are people who can handle that. And I'm sure they save loads of lives. But too much stress for me. Podcast hosting is the way to go.

3:32 Low stakes.

3:34 All right. And today we really are talking about saving people's lives, right?

3:38 Yeah.

3:41 No. That was a.

3:42 Nice attempt at a segue. I mean, so we could have a whole different episode about the development of salversan and penicillin, which are antibiotics, which actually do save people's lives.

3:51 Yay, science.

3:53 But today we're talking about the fact that in like 1493, syphilis showed up in Europe in a big way and it had not been there before. And so we are talking about sort of the history of How did it get to Europe? How do we study this? Not really how do we treat it, but I'd be happy to come back on another episode about treatment if that's what you want.

4:13 All right. So don't expect any upside, folks.

4:16 I don't think anybody who came to a Kelly episode was expecting upsides.

4:19 All right. So then where does our story begin?

4:23 Our story begins in 1493. French King Charles VIII is bringing a diverse blend of mercenaries from many different countries over to Naples where he plans on laying siege. And this group of mercenaries also has a group of prostitutes trailing behind them. And so it's a big group of people from lots of different places. They lay siege to Naples.

4:46 They win at first. They fraternize with the locals.

4:50 Are we rooting for the French here or are we just telling their story?

4:53 We're just telling their story. Yeah, we don't have to root for anybody here. We're definitely not rooting for syphilis.

4:58 You have to root for somebody. I mean, it's like when you watch a sporting event, you got to pick a side just so you have somebody to root for, you know, even if you don't actually care. Okay.

5:06 All right. Let's see. Let's root for King Charles VIII because he doesn't have many years left ahead of him. So let's hope he has a victory before his early demise.

5:18 Apologies to the Neapolitans. All right.

5:20 That's right. But eventually the Italians rise up and Spain has sent an army and it's landing and it's coming. And so the French turntale begins. and run. And all of the mercenaries from both sides, because there were mercenaries on both sides of this, now spread out across Eurasia as they go in search of new work or go back to their homes. As they spread, they bring a new disease with them. And that new disease is syphilis.

5:47 This was the first time syphilis had been reported on the European continent. And through the mingling of all the different mercenaries and the prostitutes and the Neapolitans and the French, Lots of people end up with this disease and lots of people bring it to new lands.

6:03 That sort of surprises me because I thought I remembered hearing that syphilis is an ancient disease that like we find evidence for it in like Egyptian mummies or something like that. And that's just across the Mediterranean and like, you know, Antony and Cleopatra and all that stuff. So like there's definitely like Rome and Egyptian mingling. Why didn't that happen earlier?

6:23 Well, so Roman-Egyptian mingling wouldn't have brought about syphilis if syphilis was not present in Africa or Europe at that time, which is important to keep track of. Also, another thing to note is that so lots of people say, oh, the papyrus ebers, this is this ancient Egyptian papyrus. mentions all of these diseases. And so like, as I've been studying a variety of diseases for this project that I'm working on, you'll often hear about ancient Egyptian texts mentioning these diseases. But once you dig in, the reference to the disease is so vague, it almost could be any disease.

6:59 So like, you know, for example, we don't actually think we have really solid evidence of gonorrhea until it's written about by Arabic physicians around the Middle Ages.

7:07 Right.

7:07 Despite the fact that the name for gonorrhea comes from Galen, who was way before that. He was describing gonorrhea means something like seed flow. And he was describing a disease where semen flows involuntarily at times when the penis is flaccid. And we think that actually that was not gonorrhea because he doesn't describe the absolute excruciating feeling of that you have when you try to urinate when you have a really bad case of gonorrhea. So we think he probably was.

7:36 I won't ask why you said yes in exactly that way, but.

7:39 I said yikes.

7:40 Oh, yikes, yikes. That makes more sense. But anyway, so we think he was actually describing some different disease, maybe a disease that's not even around anymore.

7:49 Oh, all right. Cool. So this is our first record of syphilis. It's 1493, the spread of the French losers.

7:57 That's right. Well, our first record of syphilis in Europe. And as the mercenary spread, so does syphilis. In 1495, it makes it to France, Germany and Switzerland. And immediately people are afraid of this disease. So the Parliament of France says, hey, look, if you have syphilis, you have to stay home until you're cured. And if you're not from here, you need to leave immediately. And so people are starting to panic. It gets to England by 1497, India by 1498, and by 1505, it is plaguing people in China. The naming is kind of funny. So people have a tendency to, you know, blame things that they don't like on people they don't like. And so the French called it the Neapolitan sickness. The people from Naples

8:46 called it the French sickness, as did the Germans and the Italians. The... Japanese initially called it Chinese ulcer. Portuguese called it Castilian sickness. Anyway, point is, it got named after whatever group a country did not like at the time.

9:03 I see.

9:06 And immediately we knew that it was a sexually transmitted infection. That was pretty obvious from the start. We pretty early figured out that moms can pass it to babies and that wet nurses can give it to infants and that infants can give it to wet nurses. But we also knew that it was new. Like physicians at the time were saying, this is something we have not seen before.

9:27 And so does the year 1493 make you wonder about anything in particular? No.

9:35 Columbus sailing the ocean blue?

9:37 That's right. In 1492, right, Columbus sailed the ocean blue, but he came back. Yeah. And he was back by this time. And so very soon after this event, there started to be speculation that this might be something that Columbus had brought from the New World.

9:54 Potatoes, tomatoes, and syphilis.

9:56 Spices, gold, syphilis, right.

9:58 Chocolate, yeah.

9:59 Yes. that's right. And, you know, it's worth noting that the Europeans, between sending Europeans over to the New World or sending people who were enslaved over to the New World, we ended up bringing smallpox, the flu, measles, cholera, chickenpox, malaria, and plague. over to the New World. And so it wouldn't be surprising if something traveled the opposite direction back.

10:25 Does that make sense?

10:26 Yeah, absolutely. Yeah, there should be some diseases in the New World that are new to the Old World. Yeah.

10:31 Yeah, that's right. And so the question is, is syphilis a disease that came from North America? And this has literally been a debate for hundreds of years at this point. And so today we're going to dig into what we know so far. And you might think that shouldn't take an hour. The answer should be yes or no. But it's really complicated because it's, you know, humans and diseases.

10:57 All right. So we're trying to figure out who's to blame for syphilis. Kelly, what are the clues?

11:03 Well, first of all, I don't want to say that this is a blame game, you know, like I certainly wouldn't blame anyone in the new world if they, you know, were colonized and then those colonizers happen to like, you know, go back with the disease.

11:15 I'm not blaming individuals, you know, it's not like, you know, it's the fault of Pablo or Sam or something, but, you know, it could be the fault of a whole continent. The way you can, like, blame Virginia for its Virginian-ness, even if, you know, all the people in Virginia are lovely.

11:29 You can thank Virginia for its Virginian-ness is what you can do, my friend. That's what I'm doing. It's fall in Virginia right now, and it is absolutely stinking perfect.

11:38 The few weeks when Virginia resembles California.

11:41 Except we have leaves that are changing color, and it's gorgeous. Okay, so here's the thing. There were theories at the time other than the Columbian hypothesis, which I just want to mention because they're sort of funny from our more privileged position today. So one of the theories was that it came because of the conjunction of Mars and Saturn. One of the ideas was that this was a God-given punishment for blasphemy. And I found this really amazing woodcut where Mary, the Virgin Mary, is sitting with Jesus on her lap.

12:09 And on one side, she's crowning Maximilian of the Habsburg dynasty. And on the other hand, there's a little infant Jesus who's like throwing shade at a bunch of people who have syphilis below. And it's not... It's like he's raining arrows of syphilis down on them. Maybe he's raining the cure, but he definitely has this like smug face, which suggests he's not raining the cure on them. So anyway, this was stigmatized even then. There were other crazy ideas like this happened because women had sex with monkeys or women who had their period had sex with lepers. But pretty soon after some of these more crazy ideas were, you know, waved away, we ended up with the Columbian hypothesis and the pre-Columbian hypothesis. So the Columbian hypothesis we've sort of

12:54 hinted at already. The idea here is that Europeans brought a ton of diseases to the New World. Maybe when Columbus was in Hispaniola or the landmass that he would call Hispaniola, he His crew fraternized with the locals, let's say, and brought back syphilis. There are some reports of people on the ships returning back to Spain having some sort of skin diseases. There were some reports written by people saying, oh, yeah, this came from the locals. The locals had syphilis. It was called something different at the time. But we now think that a lot of those reports are a bit suspect, not super reliable. And so it's not like a slam dunk based on these reports that it definitely came from the Americas.

13:35 So, you know, we are not blaming individuals, but you're calling this the Columbian hypothesis, which, you know, sounds a lot like it would be Columbus's fault. But all right, let's keep going.

13:46 That's a fair point. But the important time point is had Columbus gone to America or not, what would you call it?

13:54 Yeah, no, I'm happy to blame Columbus. That dude deserves blame, yeah.

13:57 Yeah, okay, good, good. Let's go ahead and lean into that then. And so then the pre-Columbian hypothesis is this idea that actually the bacteria that causes syphilis had been floating around Europe for a while, but either it had been causing syphilis and nobody had sort of noticed. Maybe, for example, we were confusing it with leprosy.

14:17 Hmm.

14:18 Or it was already there and it like mutated and this mutated version got super quote unquote lucky and ended up in the middle of a war with thousands of people who got bored and were having sex with each other and then spread out and brought it all over Europe and Asia. So those are the two hypotheses. How do we study them? Well, the main way we study it now is archaeology and genomics. And so let's start by talking about archaeology.

14:45 Okay.

14:46 All right. So if you are unfortunate enough to get syphilis in the era before you can get treatment, syphilis ends up with this stage where sometimes it will grow like in your bones. And when it grows in your bones, it causes this chronic inflammation that forms a hard lump. And this hard lump starts to eat away at the bony tissue. Oh, no. And in the skeletons, it leaves lesions.

15:11 Yikes.

15:12 Or sometimes it will, like, leave lesions that are noticeable on the skull as well.

15:16 This sounds painful.

15:17 Yeah, incredibly painful. And actually, right when syphilis ended up in a new area, we have, you know, historical evidence that it was much worse than it ended up being. It seems like over time it became a little bit less intense, which kind of makes sense because if you imagine yourself as a syphilis bacteria... And you cause.

15:35 I'm going to try to be sympathetic here. All right.

15:37 That's right. That's right. And you cause super intense symptoms that are visible. Then the people who have those super intense symptoms are probably not going to be in the position where they can pass it to someone else. Right. You know what I mean?

15:50 Right. They're getting overlooked at the club.

15:52 Yeah. That's right. That's right. Whereas if you produce slightly less intense symptoms, the chances of being transmitted go up. And so my guess is that less virulent strains had an easier time passing. And that's what happens. But we don't actually know the mechanism. But we do know that over time, the symptoms became less severe and fewer people died from the disease.

16:12 That's good, I guess. That is. No, that is.

16:14 That's great.

16:14 I'm looking for a silver lining here. Yeah. Yeah.

16:16 I mean, that's better than the alternative, I guess. OK.

16:20 Yeah, okay.

16:20 So if you find ancient skeletons, they leave these lesions that could be indicative of syphilis. Right. And so what you need to do are three things. First, you need to find a skeleton. You need to figure out if that skeleton is showing any indication of an advanced syphilitic disease. And this is already kind of difficult because just because someone had syphilis doesn't necessarily mean that it advanced to the stage where it was causing problems with the bones.

16:47 So you need to find a skeleton that stuck around and happened to have symptoms. Those are probably pretty low probability events. And then you need to use radiocarbon dating to figure out how old the skeleton is so you can decide if it's pre- or post-Columbian.

17:00 Mm-hmm. Okay.

17:01 And you agreed to explain radiocarbon dating, so go.

17:09 Radiocarbon dating, super clever way to figure out when something that used to be alive stopped being alive. And it relies on measuring how much carbon-14 and carbon-13 are in your body or in the object. These are different isotopes of carbon. Remember, elements are defined by the number of protons they have, but they can have different numbers of neutrons.

17:31 So carbon 12 is stable, six protons, six neutrons, but you can have carbon 13 and you can have carbon 14 with two extra neutrons. Carbon 14 is radioactive and not stable. It only lasts for around 5,700 years, which means if you have a bunch of it, then after 5,700 years, half of it's gone. Now, the cool thing about carbon 14 is is that it acts in your body the same way carbon does. So if it's in the environment, you breathe it, you eat it, you do everything, and you have some carbon-14 inside you. And it's not a big deal. It's a tiny bit of radiation. But once you die, you stop eating and you stop breathing.

18:08 And so the carbon-14 that was in the environment no longer is coming into your body. So the moment you stop eating and breathing, the carbon-14 in your body becomes a clock because it decays. And over time, you have less and less of it. So somebody who has just died has the same amount of carbon 14 as the environment.

18:26 Somebody who died 5,700 years ago is half the carbon 14. Somebody who died a long time ago has much, much less carbon 14. So just by measuring the carbon 14 to carbon 12 or 13 ratios, you can figure out when this body stopped interacting with the environment. And you might wonder like, well, where does carbon-14 come from? If it decays, why doesn't it just decay in the environment?

18:50 And it does, but the environment is also making new carbon-14 because their cosmic rays, particles from space are hitting the upper atmosphere and creating carbon-14. Yay, cosmic rays. And so constantly replenishing it. And there's an amazing science of this, like figuring out how much carbon-14 is in the environment.

19:09 How does that vary with time? Because if carbon-14 goes up or down through history, then that can throw off your measurements. And it turns out that global warming, burning fossil fuels, reduces the carbon-14 because it emits a bunch of non-14 carbon, which dilutes it. And setting off nuclear weapons enhances the carbon-14. And all sorts of events through history affect this. And they actually use the Egyptian records of the kings to calibrate this scale because they knew from other sources that when did this king die? And then they could carbon 14 date it and they get like, okay, this is off by a little bit. Let's figure it out.

19:48 And they're able to trace it back to explain, like, oh, there was more carbon 14 in the atmosphere here or less there. And you can use tree rings also because trees record this carbon essentially. You can see how much is in each ring. So it's an amazing bit of science discovered accidentally in like the 40s and completely changed archeology.

20:06 It allows you to carbon date so many things and give you really clear understanding of what actually happened. And it really changed like people's understanding of, you know, the history of humanity. We were able to like date the Dead Sea Scrolls to see that like they were really 1900 years old and date the Shroud of Turin and see like actually it seems like it was made from stuff that died in the 14th century. And more generally, it just changed like our understanding of how technology spread in prehistory. We used to think that it was created in one place and then spread around, but now it looks more like things are made independently, locally, from independent innovations.

20:46 So it's an incredible tool into the past.

20:48 That's an incredible description. Thank you. And no surprise here. Sometimes it gets a little bit more complicated. So that carbon-14 dating is based on the amount of carbon-14 in the atmosphere.

20:58 Yeah.

20:59 But if you happen to be a people who eat a lot of food from the ocean.

21:03 Yes.

21:03 The relationship between carbon-14 and carbon-13 in the ocean isn't necessarily the same as what's happening in the atmosphere. And so if people eat a lot of fish, then that can make them look older. Yeah. than if they ate entirely land-based things. And so there's a lot of calibration that needs to happen. And a little bit more calibration will sometimes happen if, for example, you have a gravestone with a date on it and you know that that person ate fish, you can say, okay, this group probably ate some fish because the date we're getting doesn't match with this gravestone. And so now we know these people in this area maybe ate fish. And so there's a lot of calibrations.

21:37 You're saying the dates were fishy.

21:38 No, yes, I was saying the dates were fishy.

21:42 And that's just because cosmic rays are creating the atmosphere. So the carbon-14 that's made doesn't mix into the ocean evenly always. But yes, there's real science there.

21:50 Yes, absolutely real science here. And these these dates, it can give you like really amazingly accurate dates. But if you're talking about something like skeletons, one of the papers that I read said it usually can't resolve the order of events if they're separated by something like less than 50 years. So it can do like, you know, amazing accuracy, but it can't tell you like 1912 or something. You know, there's like an error of at least a couple of years, sometimes a couple of decades. Okay, let's take a break.

22:18 And when we get back, we will discuss what we have learned with this technique. Or will we? We're back, and I promised that I was going to tell you what we've learned from Carbon 14 dating, but it's me, so first we're going to talk a little bit more about how things are complicated. And so here's the deal.

22:56 The bacteria that causes syphilis, whose name I won't say so that Daniel doesn't roll his eyes.

23:01 Because it adds nothing to the conversation.

23:03 Sure. Okay.

23:05 Has.

23:05 Very closely related strains, like where there's an argument about whether or not we should call these strains or subspecies or like what we should call them exactly. But they are very closely related to syphilis, but they cause different diseases. So, for example, they cause diseases called yaws. And Bejel. Bejel.

23:26 I'm so sorry. I'm probably getting that wrong. It's B-E-J-E-L.

23:29 Bejel.

23:30 Matt can go. But these are diseases that tend to be acquired in childhood and are not sexually transmitted. They're also diseases that cause sores that have the bacteria in it. And encountering that bacteria can transmit, you know, this bacteria between person to person. So there's a lot of similarities between these diseases. But in some parts of the world, instead of getting syphilis, you're more likely to get yaws or a bagel.

23:58 Bagel. Those sound better than syphilis, actually. I prefer those.

24:02 I think that's probably because you have like a bit of a stigma associated with like, like almost everybody. Syphilis is a word you've associated with something that you don't necessarily want to get. But yaws and are both disfiguring diseases as well, which can have impacts on the bones, which is to say massive impacts that are, you know, felt all the way down to the bones. And so if you pull out a bone and that bone happens to have a lesion on it, You can't be 100 percent sure that it was caused by syphilis instead of being caused by yaws or bedule. And so scientists have been trying to figure out, like, all right, well, what do we do about this? And so for a while there, we thought that syphilis was the only one of those

24:46 diseases that could transmit from mothers to babies. And so trigger warning, we're going to be talking about, you know. fetus bones, which is sad. But when it transmits from mothers to babies, it tends to have very particular impacts on the teeth. It causes what's called Hutchinson incisors. And there's some pictures in the outline I sent you. But basically, they've got teeth where the top of the tooth has a bit of an indentation and it looks like there's points on the far side of either tooth. And then there's another thing called mulberry molars, where like, you know how your molars have like ridges on them? These molars have a lot more ridges and they go all the way around in like a circle. And so these are

25:28 like pretty distinctive features of congenital syphilis.

25:33 Okay.

25:33 Which until recently we thought was the only version of this bacteria that was transmitted from mothers to babies.

25:39 And so that would help us understand when syphilis arose because we were seeing this in babies that we, what, dug up?

25:46 Yes.

25:47 Yeah.

25:48 Well, you know, yeah, skeletons that we dug up and they happened to be babies. Super sad. Okay, and so.

25:55 Is it cool that we're digging up skeletons? Like, what's going on here? This is like cemeteries we're just rifling through because of our curiosity?

26:01 Oh, yeah, that is a great question. Actually, archaeology has a long history of digging up bones in unethical ways. That field is much more sensitive to that issue now. And there's a lot of rules in place about what you're allowed to dig up and examine, what you're allowed to do, what information you're allowed to share. I am not an expert on that. We're not going to be digging into that today. We could maybe have an archaeologist on the show if you want to talk about that more.

26:26 But I am going to be talking about what we have discovered.

26:29 Yeah, OK.

26:30 Yeah. Not whether we should or not.

26:33 We're not placing blame. We're working so hard to not place blame.

26:38 I mean, you know, sometimes I think you got to place blame, but, you know, maybe not always. So there is a skeleton that we found in what's modern day Turkey now. That appears to have signs of congenital syphilis. And it was dated in this case, not using radiocarbon dating, but a technique called stratigraphy. And it was dated to the 13th century, which is pre-Columbian. So stratigraphy. is when you essentially look at the other things that are buried in the stratified layers above and below the skeleton. And so, for example, if you find a coin that like, I don't know, has a year printed on it or has like the face of a particular emperor on it, then you can say, OK, this body almost certainly came from

27:20 the time period when this person was emperor and we can date it, you know, to around that time. Does that make sense?

27:26 Yeah, I thought stratigraphy was going to be about handwriting analysis, but now it makes more sense. It's a little bit layers. Yeah, yeah, yeah. See how like weird Latin names are not so helpful.

27:36 Ah, interesting. All right, all right. You have been heard, Daniel.

27:38 All right, but we're still trying to figure out, like, when did this person die, right? And that's the goal here, so we can put together a story of, like, how this disease spread.

27:47 Yes.

27:47 So we can figure out who's to blame, but we're not going to blame them.

27:50 That's right. Exactly, exactly. Okay, and so they have this skeleton that appears to have signs of syphilis that was transmitted from mom to baby in an era before Columbus had gone to the New World. Okay. But because it's biology, we have more recently discovered that actually yaws and can sometimes pass from mother to fetus. We thought that it wasn't transmitted in that way. Oh. But now that we have genetic tools, we've been able to identify some strains and some strains that we thought were syphilis actually appear to be the strains that we had associated with yaws and like vice versa. And so now we're like, oh, well, this definitely tells us that a disease caused by that bacteria was present in Turkey. But was it what we

28:44 would think of as syphilis?

28:46 So we used to have what we thought was a very clear marker of syphilis that we saw in Turkey pre-Columbian. But now, because it's biology, we discovered it's actually muddled and we don't really know anything.

28:57 Exactly.

28:57 All right.

28:58 But, you know, that's like kind of a more exciting challenge, you know, to figure it out. I mean, yes, this is like, this is a dark... topic to be thinking about. But but, you know, like maybe we'll be up to it. Maybe we won't. And so then there was another study that found some ancient Greek skeletons that also possibly showed signs of infection with this bacteria. But again, we don't know if that was syphilis or if that was like yaws or bedule. Like we can't tell if it was sexually transmitted just by having these skeletons. But so the point is, that you want to note here is that there are skeletons that we have found in Eurasia that show evidence of being infected by this bacteria during their

29:42 lifetime and this disease reaching advanced stages, but we can't tell from those skeletons if it was syphilis or not. Does that make sense?

29:49 Mm-hmm.

29:50 It's worth noting that we've also found a bunch of skeletons in the Americas that show evidence of treponemal diseases as well. And so now we're essentially in this situation where, based on archaeology, we've been able to find skeletons on both sides of the Atlantic that have evidence of having been infected with this bacteria, but we are still kind of trying to figure out when this became a sexually transmitted disease.

30:15 Hmm. All right, well, I need a break from all these skeletons. It makes me sad. So let's take a break. And when we come back, we're ready to hear Kelly's definitive answer on whether syphilis came from the New World. Is it Columbus's fault or not? All right, we're back and we are digging into whether Christopher Columbus brought syphilis back with him from the New World. So, Kelly, take us on the path to understanding.

31:01 Okay, so we've learned a lot from the bones that we found, but it would be really great if we could also extract DNA from those bones. And by using that DNA, maybe we could get a better handle on whether or not a skeleton had syphilis, yaws, or... Bejel.

31:17 Mm-hmm.

31:18 But what's really difficult about trying to do this is that these strains are so closely related that most of their genome is exactly the same. And so you kind of can't use like, you know, in the early era of genetics, you would like pick a couple genes and then you'd use those genes to try to identify like different species, for example. But when you've got strains that are so closely related, a couple of genes won't do the trick. They're probably similar at those genes. So you need like the entire genome. so that you can make enough comparisons between these different strains to feel pretty confident that you've got a yaws-type strain versus a syphilis-type strain, for example. In 2018, we had the first genomic evidence

32:00 in an archaeological site that we were able to use, and this was from Mexico City. It was dated to the 17th century, so too late to be helpful for our pre-Columbian versus Colombian debate, but still interesting from the perspective of, like, can we do this? And they found skeletons from babies that had evidence of treponemal disease. And they were able to pull enough genomic data and they were able to say that two of the samples appeared to have the genome that's associated with syphilis. And one of the babies had the genome associated with yaws. And so this was one of the first times we were like, oh, man, yaws is transmitting congenitally. And in the same area, you can have symptoms that were caused by the syphilis strain

32:46 and the yaws strain. Oh, no.

32:49 So it's going to be like impossible to figure this out.

32:51 That is perhaps actually the point. We can wrap it up. I was going to give a little bit more information, but that's kind of where we're getting is that it might be impossible to figure this out because this bacteria does very different things. And we don't yet understand why in some cases it causes a disease like yaws and why in other cases it causes a disease like syphilis.

33:14 And it's really hard to do experiments on this kind of stuff. So it does turn out that rabbits are infected by a syphilis-like disease. So you could– sorry, trigger warning. We're talking about animal research. You could do some research there and try to figure out like what– makes the bacteria act differently? Like, are there environmental conditions? Does this depend on how the host immune system responds to it? But, you know, like, it would not be ethical to do experiments on humans to try to figure this out. So at the moment, we're just sort of stuck, not really sure what to do.

33:48 But I have a kind of basic question.

33:49 Yeah.

33:49 So we're trying to figure out if syphilis came to the New World with Columbus, but the confounding factor is that there was already a syphilis-like disease in Europe. And does this syphilis-like disease exist we think have a common origin with syphilis? Is this like there's some original disease and then it's split off and the new world version separated from the old world version and now they're coming back together? Is that the story?

34:14 Well, that's a great question. That's what we're trying to figure out now. So the question is, like, did a strain from the Americas make it to Europe and then in this new population do something totally different?

34:26 Yeah.

34:26 Or was it a strain that was already present in Europe that for whatever reason, you know, maybe like social changes changed the way it could get transmitted, plus some mutations? Like, is that where syphilis came from? Was it already waiting in Europe just for its perfect moment?

34:42 But even if it wasn't waiting in Europe for its perfect moment, there's a related disease already in Europe, right?

34:50 Right.

34:50 Doesn't that suggest that either way there's some common origin of the two diseases?

34:54 Yeah, right. And so some scientists were trying to figure out where do they think this bacteria arose initially?

35:01 Yeah, exactly. And is it aliens?

35:03 Yes. Well, I should have guessed we were getting there, but that's not what I had on mind.

35:10 Was it cannibalism?

35:11 It was cannibalism. Yeah. And white chocolate and smoking banana peels. So anyone who's got their DKU bingo card, you're welcome.

35:19 That's right.

35:20 So there was this 2024 paper that looked at ancient genomes to try to figure out where did this bacteria come from?

35:27 Yeah.

35:28 And they think that this bacteria originated in the Americas. And it looks like the upper bound for a common ancestor for this bacteria, so like when this bacteria split from another bacteria, is like 9,000 years before Common Era. So really, really long ago. It's possible that it jumped from another animal into people. We really don't know. But it's been around long enough that like, you know, could it have gotten across the Bering Land Bridge? Like when people came from... Europe over to the Americas, could it have gone the other way as well? There was also some evidence of Vikings coming over this way at some point in the past. Maybe the Vikings picked it up and brought it back over and it's been there since

36:12 the Vikings visited. And so we don't know the answer.

36:16 Are you saying Scandinavians are syphilitic people?

36:18 I am. Why are you doing this? No, I'm not saying that. Absolutely not.

36:23 Because those are my people. You know, I'm married to a Danish lady, so be careful.

36:27 I can tell that you're very defensive. Yes. I mean, we do think that we've seen the yaw strain in bones from Finland from the 15th and 16th century. But 15th, 16th century is like, you know, it overlaps the Colombian date that we're all interested in.

36:44 So.

36:45 It looks like this is ancient. We don't know when it made it over to, like, Europe for the very first time. But it's pretty old and appears to have started in the Americas.

36:54 And tell us why scholars are interested in this. Like, I think it's interesting just because history is fascinating. And I like to know, like, how did we get here and what happened and, you know, how small things can snowball into big effects. But, like, why are the archaeologists and the historians excited about this?

37:11 Yeah, that is a great question. So I think part of it is because this is a debate that was like written down in historical records like hundreds of years ago. And so I think to some extent, like, you know, historians and people who are interested in history like want to know the answer.

37:25 It's like the Navier-Stokes equation, but for history. It's like a longstanding open problem.

37:30 That's right. How old is the Navier-Stokes equation?

37:33 Not as old as this one, no.

37:34 Okay, yeah, yeah. But I'll note that when I was reading a lot of the recent papers written in the last couple years, the authors are clearly exasperated with the fact that when they say that they study treponemal diseases and their history, people are like, Did Columbus bring it from the new world to the old? And they're like, look, that's not what's important. What's important is the impact this disease had, whether it was yaws or syphilis, like whatever it was, the impact it has on the communities that you find it in over time.

38:07 You can sense their frustration in their writing and their like dry academic prose.

38:11 I mean, there was a 2025 paper where they were not pulling any punches. They were like, look, we are going to review the literature on the Colombian pre-Columbian debate, but we do not think it's interesting. And I was like, oh, wow.

38:23 That's like Katrina saying like, our virus is alive. She doesn't care. Like, it's not an interesting question. And I think like, is Pluto a planet? Like, whatever. It's just an arbitrary dotted line.

38:34 Yes. I mean, I think like evolutionary biologists and epidemiologists do think that this question of what causes this bacteria to take different forms, that's an important question. And like that might even help us understand... You know, the worst impacts of this bacteria and maybe even how to control it or how to treat it. Those are important questions.

38:56 But like at the end of the day, I think most of the scholars are like not super interested in this Columbus. And part of their lack of interest might be exhaustion. Like we've been talking about this for so long. We'll probably never get a slam dunk yes or no answer. But what we do know is that it was in both places and it's complicated. So let's wrap it up.

39:16 What are the take home messages here? One of the papers that I looked at that was looking at like ancient DNA, trying to figure out where this disease came from, ended up saying that like, look, DNA might never be able to answer this question. I know. And if DNA can never answer the question, then we probably can't really get an answer.

39:34 Oh, wow.

39:34 That's frustrating. I know. And then that review paper that I was reading that was, like, clearly exasperated with the Columbian question, they were pretty much like, look, the Columbian hypothesis doesn't have a lot of evidence now that we know that this bacteria was in Europe before Columbus got here.

39:52 And so... Maybe it didn't come from the Americas. We already had the strains here. And like we're probably not going to be able to slam dunk this one way or another. And again, they don't think that's an interesting question. And so thank you for spending 45 minutes with me on this question that they don't think is interesting anymore.

40:07 But but I think that like what's interesting here is that every time we dug in. there was another layer that we had to understand. Like there was another set of interesting questions that help us understand like evolution and the lives of people and like what, how different people suffered at different times and like, you know, like windows into what their lives were like. And, you know, often when we look at the things that are around these skeletons, we also get a sense for like how people cared for people who had syphilis. We get a lot of sociological information as well, which I think is really interesting.

40:41 Super fascinating. And I'm pretty sure Tony Soprano would be happy to hear that you can't blame Christopher Columbus for syphilis.

40:47 We can blame him for lots of other things. You know, I think the diseases that got brought from the old world to the new, I read an estimate that it killed something like 85 to 90 percent of the people who had lived in the new world already. So absolutely devastating. We can blame him for that. And anybody who wants to learn more about syphilis or this question should check out Alice Roberts' book Crypt, Claude Quetel's book History of Syphilis, or Oriol's book The Scars of Venus. These are all like really interesting histories, in some cases about syphilis. And I can tell you from experience that if you read the history of syphilis on a train, you won't have to sit next to anyone. One person got up when

41:28 they saw what book I was reading and moved away. And then the person who sat next to me next said, what are you reading? And then I said, the history of syphilis. And he backed away a little bit and said, for personal reasons? I said, no, not for personal reasons. And then we had a lovely conversation about the Colombian and the pre-Columbian hypothesis.

41:51 I would have said, I'm reading How to Get Rid of Nosy Train Neighbors.

41:54 He was very nice, actually. We had a really nice conversation. Actually, his interest in the conversation that we had is what made me think this might be a good podcast episode. So glad he asked.

42:05 Well, thank you for taking us on this historical journey. I'm always interested in what happened, how we got here. And I'm impressed by the archaeology and the detective work involved in trying to unravel the history of our existence. So even though it hasn't been solved, I think we learned a lot along the way. Like, don't get syphilis and don't be Christopher Columbus.

42:26 Yes, right. Also, but, you know, I just want to say real quick, we do have treatments for syphilis now. It doesn't have to have a stigma in general anymore. Sexually transmitted infections can happen to any of us.

42:40 So talk to your doctor, folks.

42:42 That's right.

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