God and the Black Death, Part 1

I was like, wow, yeah, that sounds really interesting. But Robert, I gotta admit, this is one of those topics where something sounds really interesting with then as soon as you start getting into it, you realize, oh, no, it's one of those word the more I read, the less I know. Um. That is definitely the case with the historical scholarship on religious responses to to the plague this it seems like

this is a really complicated area of research. Yes, i'd say a complicated area of research and also a robust and thriving area of research. And I think that's something that I might surprise some listeners out there to know that like the Black Death and the study of the Black Death and our attempt to understand uh, you know, things like mortality rates and how it's spread, and and then how people responded to it, and it's and its

effects short term and long term. You might think that this is this is a matter of the history books. This is something that has been settled for decades, if not centuries, and there's perhaps very little, like just some fine tuning of the research these days. But it's not the case. There's a lot of work that goes on in this area of study, and there's still exciting stuff

coming out. I mean, you go back a couple of decades and it seems like a lot of what people were arguing about was whether or not plague was caused by plague. Yeah, and I remember this. Uh. I don't think I ever wrote anything specifically for how Stuff Works dot com about the Black Death. Maybe I had to cover it like briefly in some sort of you know, like a top ten pandemics type of an article or something.

But I remember at the time this being the case where there were these different different theories about what it might have been. Was it perhaps this particular ailment or disease, was it this one, or was it actually what we think of as bubonic plague? Yeah, and so at least I think that question is mostly settled. We can give a fairly firm answer on that one today. But I was just surprised how much about the plague pandemics is still up in the air or has been questioned or

is still controversial. Uh, And and how often a fact you thought you knew about it might not actually be correct. But anyway, so I was also wondering, like, how did you get interested in this? What what made you want to talk about the Black Death and and the powers

of God? Oh? Well, I think part of it was I was I picked up and burcos the Name of the Rose again when I was reading through through that, and I was reminded about how it's it's mentioned that brother William eventually dies in the plague or is lost in the plague, and like knowing that the egg is the thing that comes the Black Death specifically, uh, is the thing that comes after the events of the novel and um, And so sometimes that, you know, makes me

think about the world that is described in that book and and how how it's going to fare against a threat like this. And then of course it goes without saying, uh, you know, we're we're recording this, researching this during uh an ongoing global pandemic, and so I think it's it's something that has been on a lot of people's minds. A lot of people have turned their minds back to historical plagues. Um Now, of course, in fighting this pandemic COVID nineteen, we we have a number of tools not

available to humanity during the late Middle Ages. We know what actually causes the illness we're facing, we're able to figure out how it works, and we have both treatments and most marvelous of all vaccines that we can use. And speaking of vaccines, go get vaccinated against COVID nineteen if you have the ability to do so, and if you're not sure, talk to a medical doctor and find

out what you need to know from them. So obviously there were no vaccines in the time of the of the Black Death in the fourteenth century outbreak of of the plague. But also there really weren't any treatments. I mean, if you get plague today, we know today that it is a bacterial infection and if caught early, it can be treated pretty effectively with antibiotics. I mean back at the time of the Black Death there there there really

were not effective interventions at all. Yeah, it's it's really kind of staggering to to think about it, to think about to imagine a time right before the Black Death, and just think about what a mismatch this was medieval societies versus a deadly contagious disease caused by UH an invisible bacterium. The disease, on one hand, you might say, you know, understands its human adversaries to a certain extent, you know, UH, and not that it has a will or an intelligence, but it gets in there and it

does its thing. The humans on the other hand, I mean, they have the gift of reason, certainly, they have technology and society, but they lack a germ theory of disease. They don't really know how the enemy in this case, the Black Death, how it functions, or even truly what it is. So they're blind in many ways. And on top of that, they have leaned into a supernatural understanding

of the world. They believe in gods and saints and demons and miracles, and they trust in religious organizations and religious authorities or in many cases powers that are ordained by religious authorities. Another way of looking at things in this scenario is that in some ways, you have humanity stranded between two unseen worlds, be at least partially invisible world of disease and then the invisible world of religion. Uh So, you know, it's like, this is the matchup.

How will these religious organizations and authorities respond to the Black Death? What chance do they have? And so in this episode, in the whatever episode or episodes follow it. Well, I thought we might get into that a little bit and talk about how imperfect societies respond to what is in many ways, you know, a perfect pathogen with a focus on on religion. But before we get into the religious stuff, we will have to talk about just like what was the Black Death? Uh as far as we

understand it? Okay, Well, I guess we should start with that question. What do we think we know today about the nature of this disease? So first of all, let's just talk about like what do we mean we mean the Black Death versus like other plagues? Right, So, historians generally consider the Black Death to have lasted from around thirteen forty six uh ce obviously to thirteen fifty three throughout Afro Eurasia, more or less on the heels of

the Great Famine of thirteen fifteen through thirteen seventeen. And

this this will become important in a bit. But now one thing that's important to consider, and this is true of of multiple cases of plague pandemic in the world that we'll talk about in just a set can The black Death is a term is sometimes applied to this sort of initial outbreak that has been widely studied as having happened and say like uh, Europe in the Middle East, around the Mediterranean beginning around thirty six or forty seven,

and then continuing for some years after that. But each of these pandemics is not contained to just a few years. There are these recurrent waves. So there will be an initial wave of infection and then it just and then it sort of goes away for a while within a certain region, but then there will be subsequent outbreaks throughout different regions over the following uh centuries really in the case of the one that begins in the fourteenth century and uh and one of the papers I was looking

at was was calling these recurrent waves. Yeah, yeah, So it's important to realize that the Black Death of the fourteenth century, it's not thought to be the first great outbreak of playing in the Old world. The Plague of Justine In occurred between UH five forty one and five forty nine see. And it was also not the last pandemic of plague, as major outbreaks would occur throughout the fourteenth and seventeen centuries, including the Great Plague of London

in sixteen sixty five and sixteen sixty six. But the fourteenth century outbreak is what is generally referred to when we talk about the Black Death, a pandemic that claimed the lives of between seventy five and two hundred million people and reshaped society for the survivors. I've seen drastically different estimates of what percentage of people within certain regions the Black Death killed. So I think this is not

a settled question. It's something that has to be you know, it's not like there were just like there was a census of people and you can chart everyone who died. Has this is a number that has to be established through estimates. But like in on cases, you have good data to go on. You know, you can look at essentially death rolls from certain certain regions and certain time periods, and then some work has been done in me in

in examining cemeteries and the like. Yeah, exactly, as a one figure I looked at for the Black Death said that the Black Death and its recurrent waves may have wiped up somewhere between one third to two thirds of the population of Europe. Anyway you shake it, a lot of people died. I mean, you know, in any variants in the numbers doesn't really take away from just how

how brutal this was. Now, one source I was looking at and all of this was the The Anthropology of Plague by Sharon in de Witt, published in Pandemic Disease in the Medieval World, And this was from One of the things that DeWitt talks about is the idea that again, this this particular outbreak of plague, the Black Death, is following a period of rapid population growth and plenty due to warm climates and advancements in agriculture. When the warm

period ended, however, there were ripples throughout Europe. There was less food. Uh, there was famine, There was a you know, there's an abundance of labor under a feudal system. So most people during this time experienced a decline in their

standard of living. Non plague illness and malnutrition. Uh was was running rampant, and so there's this this strong argument to me, may the do it writes about it length that this put made them even more susceptible to this new disease or this new outbreak of a disease that had previously ravaged parts of the region. Yeah. And and this has been another major trend in writing over say the past hundred years about the about the Black Death

of the fourteenth century and its recurrent waves. What what, how exactly does that get situated within the broader social, economic, and cultural context of the time which had occurred, What what led to it, what exacerbated it, and what changes

did it bring about? Because it's widely believed that I guess we're not going to get super deep into these particular historical theories, but there have been a lot of theories about what rolled the Black Death may have played and say, revolutionizing the economic history of Europe, and uh, did it in some way trigger changes that might lead to things you associate with the Late Middle Ages or

the Renaissance exactly? Yeah, And you know, I think it's it's also one of these things where you look at some of the older scholarship, or if you just look at sort of generalized um, you know, summaries of the Black Death, you know, and it's often pointed out, well, this affected everybody. It didn't matter what level of society you were you were at, and to to a to a large extent, that is true. I mean, people died

at every every level of society. And there's this kind of idea that you know, the Black Death is it's it's you know, you get into these religious ideas of the judgment of humanity and it seems like it's just everybody is is suffering equally. But uh, does that hold up if we start looking at different populations, be at things like population density or dealing with you know, large portions of the population that are malnourished and so forth. Anyway, here's a is a quote from de Witt in that

article I mentioned quote. The very high levels of Black death mortality and the results from hazard analysis, which indicate that this mortality was selective and targeted frail people of all ages, means that the epidemic might have exerted a strong selective force on the northern population, removing the frail list unhealthiest individuals on a very large scale. You have the post Black death population included individuals who were exposed

to and survived the Black Death. This episode of selection might at least in part, explain the very rapid apparent changes in medieval plague epidemiology. These changes include the apparent

decline and plague mortality as described in contemporaneous historical documents. Okay, so what's she getting at their um, So she's getting into this, you know this idea that Okay, so that the plague hits, it wipes out a lot of people, a lot of people that at at at all levels of society and all ages that may have been extra susceptible to the ravages of the disease. But then afterwards you perhaps have have a certain resistance in the survivors.

But then she also points out that, on the other hand, patterns of human plague deaths might reflect the disease dynamics of nearby animal host populations, which can influence exposure of humans to plague. And we'll get we'll get into more of like what that means later about about about the

disease dynamics and animal hosts. But but you know, it also might mean that survivors were in better shape to survive the plague and or had better access to nutrition or standard of living in the years after the Black Death had had really ravaged the population. Because after the Black Death, there's this idea that you ultimately end up with potentially more sustainable population, potentially and improved gene pool

with possible resistance to the plague. The feudal system was was weakened by all of this, potentially paving the way for further changes. Um This is a direction a lot of the scholarship goes in. Yet, what what does it due to the world that allows a certain amount of a rapid change to take place? Um or introduces new

changes that could occur at the you know, the socioeconomic level, etcetera. UM. Of course, on the other hand, I think we have to be careful about getting into that, you know, that sort of uh, what doesn't kill you makes your stronger idea that like, you know, the plague was good. It just it strengthened everybody has and made a better world because, uh, in the words of Conan O'Brien, what doesn't kill you almost kills you. So it was still a period of

great suffering and death. I meant to an extent that it's it's it's difficult to imagine. And of course that is going to have, um have an effect on the survivors that goes beyond just you know as any kind of like fitness that results any kind of resistance to to illness, or an improvement in your access to UM,

you know, to to a higher standard of living. Right, So you shouldn't be lured into thinking like, oh, well, if after the plague the people who were of tended to have a hired resistance to disease and may have there may have been some economic benefits for them, that that doesn't mean like the plague was a good thing, right, right, And I mean, plus, there's a lot of a lot of great data on just how events of this nature. I mean there's a lasting effect of say malnutrition on

on one's descendants that sort of thing. So to be clear, plague bad, plague, plague very bad. I think I think that is one of the firm facts we can we can say consensus on that. Now, what was the plague? Well, uh, as we mentioned earlier, there were various alternative theories and hypotheses. I mean, I guess they're still technically are alternative theories and hypotheses, but none of them have enough support to rival.

They now commonly agreed upon understanding that the plague in question was bubonic plague caused by the plague bacterium your Cinea pestis. Yeah, so it seems like in the late twe aeth in early twenty first century, there was some of this academic debate about the infectious agent driving the

black death. But yeah, I agree, it does seem like it is a pretty firm matter of consensus now that that the black death beginning in the fourteenth century was caused by your Cinea pestis, and that bacterium that that bacillus was is something that we've known about since the year eighteen ninety four, when it was discovered I think by two different researchers pretty much simultaneously. One was Kitasato Shibasaburo of Japan and the other was Alexander Yeerson of France.

So I think from his name Yrson, you get your Cinea, the genus name of the bacterium that causes the plague. Uh. And so this was around the year eighteen ninety four, which was also the time of the eighteen ninety four Hong Kong outbreak of plague, which was a major part

of the Third plague pandemic. You mentioned that there there have been three major plague pandemics in history that we know about, the Plague of Justinian beginning in the sixth century, then the Black Death began in the fourteenth century, and then this more recent one from the from the nineteenth and twentieth century, right, and they've been There's been been some other stuff sprinkled around in there as well, but

those are the big ones. Now. You're cine epestis, As the CDC points out, it has a place in nature, even in the modern world, even in North America. Uh, your seny epestis is transmitted by fleas to a variety of rodents. Uh that certainly in these rodents certainly include the rat, but they also include squirrels, chipmunks, vols, and rabbits. This situation is is relatively stable, it's thought, with the bacteria circulating at low rates and without excessive mortality again

in these rodent populations. Yeah, so as with the number of zoonotic diseases, humans are not not the natural host

of this bacterium. You're sinning epestis, your cine Epestis lives in this natural cycle, I think it's sometimes called the Sylvan cycle, traveling between the bodies of fleas and small mammals generally rodents like rats, like you say, And then the bacteria multiply within the gut of the flea, and then when the flea bites a rat host to suck its blood, it sort of spits up some of the infectious bacteria in its gut into the rat and can

infect a new rat host. But of course sometimes infectious microbes can jump from their natural host species to another, like humans, and and this is where you get zoonotic diseases like plague. I was actually reading an article in Scientific American. I think it wasn't originally in SIME. It was a reprint from Quanta, but it was by an author named Carrie Arnold from that was covering a study published in Nature Communications in about the evolution of this

bacterium of your Cineopestis, which causes the plague uh. And the paper was by Zimbler at All called early emergence of your cine Epestis as a severe respiratory pathogen. And so the authors were looking into the question of where did your Cinea Pestis come from and how did it become so virulent? And so they write in their abstract

as follows. We showed that the acquisition of a single gene encoding the protease p l A. I think I'm not sure if that's pronounced play or plot, but it's p l A. P l A was sufficient for the most ancestral, deeply rooted strains of why Pestis to cause neumonic plague. And we'll get more into the different varieties in a moment, indicating that why Pestus was primed to infect the lungs at a very early stage in its evolution.

As why Pestists further evolved, modern strains acquired a single amino acid modification within p l A that optimizes protease activity. While this modification is unnecessary to cause neumonic plague, the substitution is instead needed to efficiently induce the invasive infection associated with the bubonic plague. These findings indicate that why Pestis was capable of causing new monic plague before it evolved to optimally cause invasive infections in mammals soneumonic plague.

The version in the lungs is is, as we'll explain it a bit, the most deadly form of your cineopestis infection. But but it has probably existed longer than the bubonic form of infection. But once the bacteria evolved the ability to cause the bubonic plague, the main version of the disease associated with the black death, the disease function of this bacterium was in a sense probably optimized for maximum

infectious potential. And then this this article by Carry Arnold quotes a microbiologist from Northern Arizona University at Flagstaff named Paul Kim who mentions that with your cine apestis quote, a single bacterium can cause disease in mice. It's hard to get much more virulent than that. Uh, and so that that's an incredibly infectious agent. That's if you're trying to set up like a thunder dome of bacteria, it seems like you're sine epestis could be a sort of

infecting champion. If a single bacterium can can cause this disease. Well, yeah, so, as like we said that the idea is in in the natural model, it's just um, your cine epestis and these rotents but then these complications occur, so for starters, sometimes for different reasons, the death rate in the desired rodent hosts population goes up and the fleas have to

go somewhere else. UM. And other times you have you know, people coming into close contact with these animals, with these fleas, and we see these these these spreading events occur, and the flea still has to feed, so it might move on to other animals, including domestic animals and ultimately human beings as well. Now humans can acquire it from handle handling the bodies and pelts of infected animals. UM. Dogs are apparently less likely to become ill, but can still

bring the fleas into close proximity with human beings. Interestingly enough, cats typically become very ill with it, and they can also directly infect humans through their cough if they if they have the plague. Did you see anything? I feel like I saw a headline somewhere recently about about an outbreak of plague among mountain lions in North America. Do you know what I'm talking about? I did not see that article, but I mean, based on this information about cats,

it sounds like it could be very destructive. Okay, yeah, I just checked that I was remembering this right. This was from a couple of articles from April of last year in that found that in Yellowstone and Yellowstone National Park in the United States, Uh, there has been an outbreak of plague that has been killing cougars in the park. Strangely, this does kind of connect to, uh, some stuff I've

read about. So it's pretty rare for people to get to get plague in the United States today, but it does happen, and sometimes some of the cases I've read about it happening were from contact people had with animals in parks in like wildlife refugees. Yeah. Yeah, close proximity to these animals definitely is is one of the driving

driving forces in those those spreads. Now we should we should stress that with these these modern outbreaks generally they don't do not spread as fast, uh, and then ultimately we're better able to treat these infections today. But yes, to be clear, the way plague tends to spread to human beings and includes flea bites, contact with contaminated fluids and tissues, and infectious droplets, and this sort of goes along with that. There are three main different versions of

the disease. So they're all caused by the same bacterium. They're all your cine epestis. But depending on how you get infected, you can have different manifestations of disease within your body. And the most most common version is the one you probably read about in school. It's the bubonic plague, the one that begins with probably some kind of bite from a from a parasite like a flea in the skin, and then can eventually infect the lymph nodes. It causes

swelling of the lymph nodes. You get these these bulbs known as bo bos, and this also comes with like very severe flu like symptoms. But then there are these other less common versions of the plague disease that have their own characteristics, such as septicemic plague which derived which comes from an infection of the blood, and neumonic plague, which is an infection of the lungs. And that one is, uh, from everything I read, pneumonic plague is the worst one

of all. Yeah, I mean they are varying um infection stats. I was looking at on the three and you know, it kind of depends. I think I know who you're looking at. But but certainly, yes, certainly the pneumonic plague is is pretty bad. But I guess one question this gets us to is the question of what are the mechanisms of transmission? How was the plague actually spread in

especially in these giant outbreaks and pandemics from long ago. Yeah, so the way it's spreading, you're gonna have different speeds involved, right, So, um, the speed at which it tends to spread when it's based on flea transference is going to be different than the way it seems to spread if it's based on droplets in the air of people coughing and close proximity to one another. So you read you read some of these, uh, these various ideas about what was happening with the with

the Black Death, how was plague spreading? And one idea that you you see is that well, perhaps it was spreading rapidly because it was primarily due to these droplets and it was a largely pneumatic plague that was really wiping people out. Um. And if if that were true, it would it would kind of be ironic, I guess,

because what do we think of when we think of plague. Uh, we often think of plague doctors, right, we think of those uh, those outfits with the the you know, the big robe and the long bird like beak and the big hat and the staff. Um uh. And then when the staff of the idea being that it's you know,

to garments, but also perhaps to distance yourself from someone else. However, always worth remembering that the plague doctor outfits and mask I do not believe we're introduced until later in the seventeenth century, and wouldn't so even if this was a design that was out there, you know this, and there's some disagreeance on how much it was actually used, but it certainly would not have been used during the Black

Death itself. It would have been subsequent plagues. Well, yeah, it would be some of the recurrent waves from that ongoing pin to make that begin in the fourteenth century, right, And and then of course the other question would be what would it have worked you know, um, well, ultimately the design of those later plague doctor masks, it was more about purifying bad air and keeping bad air from touching your skin. So uh, you know, you could make a case for it might have helped in some ways,

but not for the reasons president in the design. You know. Yeah, one thing that's kind of difficult to understand. I've been reading about the for example, in one paper looking at um recent scholarship comparing the responses of religious communities of Christians, Muslims,

and Jews around the Mediterranean at the time. Uh, and what what For example, the question of like, what they thought about the idea of contagion, you know, was it was contagion within the epidemiological vocabulary of people at the time. And it seems like too, even though they didn't have a germ theory of disease, like they didn't understand fully that diseases were being caused by tiny, you know, life forms that were replicating within their bodies. There were some

people who had some form of an idea of contagion. Uh, though the the transmission mechanism itself might have been obscure to them. There were people who thought like, well, you can observe that plague tends to proliferate within a building, so people within a house, then everybody else in the house starts to get plague. And then if you go to a place where there's a lot of plague, you're

more likely to get plague. And so that might have been explained in terms of something like miasthma theory, where you might think, well, they're just bad vapors around there, and if they get into you, maybe if you breathe them or they get on your skin, those will harm you. But I think there was also an idea that maybe sometimes sick people have some kind of particles coming off of them, and you want to prevent those particles from touching you, And so this might have inspired some of

these full body coverings. You see what the plague doctor outfits that, you know, you would have big coverings that might have been covered in some kind of waxy substance or something to try to really keep stuff out, and then you tuck it all in, like you tuck your shirt in, and you tuck your gloves in and everything to kind of just prevent stuff from getting on you.

And even if they didn't have a germ theory of disease, that in itself might have been quite useful in um in keeping out various vectories of infection that we can talk about in a second. Yeah, but then again it can you can also use this of the same logic to then to make judgments like, well, plague is here, I don't want plague. We should all go over here

and then we'll be safe. Yeah. Yeah. So so ultimately without really knowing your enemy in this case, really knowing what it is you're up against and sort of the rules that it adheres to, you know, there's also there's still a lot of guesswork involved, and sometimes you're kind of accidentally or maybe not quite accidentally, I mean, making some leaps based on logic, getting to some level of understanding about what you're dealing with and how disease works,

but in another case is missing it. Yeah, that's right, And it's still like it still seems like there is actually still a good bit of scientific controversy over what are the primary routes of transmission for plague at various times in places um the sources I've been looking at. So it seems like the more classical understanding was that people were mostly infected with plague by proximity to what

are called commenced old rodents. Uh. Commencel comes from I think the term term four sharing a table together, sharing meals together. That commence al rodents would be like rats living in or near your house, and that those rats would get in a plague infected fleas on them and then from the rats, the fleas would jump to humans and bite them, and those bites would develop into bubonic plague.

And then, of course sometimes bubonic plague can turn into pneumonic plague, so you can have so this is a little confusing, but you can have primary pneumonic plague where the infection route is inhaled droplets that infect the lungs.

So if somebody like coughs neumonic plague and then you inhale it, that you can get primary pneumonic plague, or you can have secondary pneumonic plague where you're first infected with the common form of the disease, the bubonic plague, and then that progresses in the body and develops into the lung infection into pneumonic plague, and then you can spread it to others through droplets, through coughing or whatever, and of course the people who got it that way

would have primary pneumonic plague. And again pneumonic plague is uh extremely deadly and in fact, to introduce a study I was going to mention next. So there was a study published in p N A. S by Katherine ar Deane at All called human ectoparasites and the spread of plague in Europe during the second pandemic, and the authors they're writing about the different forms of plague, they write that quote, secondary neumonic plague develops in an estimated twenty

cent of bubonic cases. Uh, and this creates potential for primary pneumonic spread, even if it is not the dominant transmission route. So they're not saying that the plague was primarily spread via droplets coughed by people who had pneumonic plague, but that can be one way that the plague spreads. So maybe like twenty of the people who get bubonic plague eventually end up with pneumonic plague and then when

they're coughing, it's going all over the place. But anyway, I wanted to talk about this study itself by by Dean at All from because this offered some evidence, some evidence based on epidemiological modeling to try to solve the question of what was the primary route of transmission for

plague in various places and times. So there's this consensus that yes, the Black Death was caused by your cinea pestis primarily manifesting in the bubonic plague form, and this is backed up by multiple lines of evidence including DNA analysis of remains from places like plague cemeteries. But there are still these remaining questions about which route of transmission was the most responsible for the horrible outbreaks we see

chronicled in Europe, Africa and Asia. Now just once again, some of the previously known major ways that a person could become infected with with plague would be first of all, being bitten directly by a flee from a disease carrying rat, and then the second would be inhaling droplets from a person infected with the pneumonic version of the disease. But there are some reasons for doubting either of these methods was the primary route of transmission for most plague infection

in the second pandemic. And I think some of these doubts come in the form of a lack of direct evidence for examples, as the authors here say that, you know, if you were to have a lot of plague coming directly from rats to humans, you would probably expect to see physical remains indicating huge rat die offs, what they called rat falls, and they say that that we don't

actually have that. And then the other thing is circumstantial analysis like the spread of plague was often very rapid in a way that the authors argue can be difficult to explain given given either one of the preceding vectors, so say, from directly from rats to humans or droplets from the pneumonic plague. And one problem with spread via the pneumonic plague is actually that with pneumonic plague tend to get very sick and die extremely fast, and this

sexually limits its transmission disease. A disease that kills its host very very quickly can actually be less likely to spread because it's so deadly, right, And this is something that's been driven home about it and the current pandemic with with COVID nineteen is that it it's it doesn't kill people off immediately, it allows for this kind of spread and can and then that's one of the reasons

we're in the place we are now. But in this paper, the authors here explore a third alternative which they didn't invent. This is something that has been hypothesized and debated in in previous research, but they're exploring and trying to model this third alternative, which is human to human transmission through the intercession of human ectoparasites. These would be things like fleas and lice, but not jumping off of an infected

rat and biting a human and then infecting them. Instead had specific human ectoparasites like human fleas or pulex irritants or human body lice or known as peddiculous humanis humanis, And so the idea here would be that there might be some initial infection case that would come from a wild animal reservoir, but then once it is in humans, human ectoparasites like the fleas and lice living on human bodies would bite the infected human and then carry the

infection and then go bite another human and infect them. So the primary responsibility would would look more like a human to human direct spread versus something that is that is mediated by by a rat reservoir. So we're basically talking about an all new loop that develops like not not the the rat and rat parasite loop, but a human and human parasite loop. Right. And I want to be very clear that this this one study here does not mean like the question is settled and it was

definitely the human ectoparasites. I think there's still a lot of open questions and plenty of room for debate about what were the main transmission vectors in these different places in times during the Second Plague pandemic. But UH, the authors here at least found is one line of evidence

in favor of the human ectoparasites hypothesis. UH that this evidence was they ran simulations of epidemics based on the three different transmission vectors and what could be known about them about like how fast you would expect them to spread and what the mortality would be and all that. So they created these mathematical models for spread by primarily pneumonic droplets people getting pneumonic plague and then coughing and infecting other people, and then flea bites directly from rats

and then spread via human ectoparasites. And they compared these models together um based on existing data about mortality rates from nine known locations of plague outbreak in Europe during the Second pandemic, and according to their model, the human ectoparasites spread fit the day DA better than the other methods of spread did. So they think this is one good line of evidence that the primary way plague was

spread at this time was via these human ectoparasites. It was human to human but primarily from little things getting on you that bite you and then jump to another

person and and bite them. And even if few people so again, we we don't know that this is correct, but it's an interesting idea, and it makes me think about how even though few if any people would have understood the vectors of the disease in this way at the time, Uh, it doesn't make me think about how if you read plague treatises and people writing about the plague at the time, I recall a lot of things mentioning clothes like infected clothes and bedclothes of the deceased,

and and the idea of you know, touching the things they wore and all that being being dangerous, and that that makes me wonder if I'm remembering that right, I mean, that doesn't make me wonder if there is, in a way something people are picking up about places where you might expect to find the ectoparasites of infected people. Yeah, yeah,

that's a good point. I mean, on the other hand, if these were people suffering from extreme flu like symptoms, it also made might might make sense to steer clear if their their their garments and their their sheets and so forth for other reasons, because of potential fluids and whatnot. Now I saw some some coverage of this particular study. I think one of them had a headline that was essentially something like rats are off the hook for the Black Death. Uh, come on, do you think do you

think that's fair? I mean, I guess I get halfway fair if you're trying to be cute. I mean, of course, given the understanding that it's not just like one study and then you're done with the subject, like you know, you're you're building a base of knowledge, and you'd see how this would compare to other lines of evidence for

and against the idea. But even then I think it wouldn't be fully rats are off the hook because I if I'm understanding this idea correctly, I think it would still be the idea that there is, of course a natural rodent reservoir, and this is where you're sending Epestis lives in its standard cycle, it's cycle in the wild, and so at some point the jump would have had to happen. You would just say that rats are not

primarily the thing carrying it to each person who gets infected. Right, thank thank So, it seems like we know, second plague pandemic almost definitely was your cine epestis, you know, hitting people primarily in the bubonic disease form. But there are a lot of interesting, still as yet unsettled questions out there about it, how exactly it worked, and research goes on. Yeah, and then you know, there's so many different factors when you start looking at you know, what causes uh, um,

plague episodics and and outbreaks. Uh. You know, you have so many different factors to take into account, like like higher high rates of death among reservoir rodent species, climate related factors, you know, cooler summers following wet winners. That seems to be a factor as well that I've seen highlighted. Um. And then you can also throw in things like high density human populations, uh, you know, multiple rodent types living

within that population and so forth. Um. But one of the big questions that often comes up is Okay, well where did it actually come from? Which you know, in some in some ways that's a loaded question because, like I said, you can you can in North America, you can essentially like wander out into the wilderness and there will be plague somewhere out there. Their rodent reservoirs um all over the place for it. But in terms of like this particular outbreak of the you know, the Black Death, Uh,

there's been a lot written on it. I was reading was the Black Death in India and China by George D. Sussman. Uh. This was published in the Bulletin of History of Medicine in twenty eleven, and in the author first explore some of the early understandings about the geographic origins of the

affliction and then moves on into other areas. So there was apparently an under standing in the fourteenth century, evident in the writings of fourteen century Italian lawyer Gabrielle de Musis that the Black Death had struck throughout the known world, that it was an international crisis, perhaps of biblical proportions as play, and it was hitting places so far away that they were almost mythical, that even those places were

struggling with plague. And then he goes on to mention, so a lot of the scholarship that we have comes from the Christian in the Islamic worlds Uh. He goes on to mention fourteenth century poet Uh even al Lardi, who was situated I believe in Aleppo, which is in modern day Syria, and he spoke with merchants who had traveled and observed the plague elsewhere, and he himself would die of the plague in thirteen forty nine. But he wrote that the pandemic had begun in northern Asia, in

what he called the land of darkness. Quote China was not preserved from it, nor could the strongest fortress hinder it. The plague afflicted the Indians in India. It weighed upon the send it sees with its hand, and ensnarled even the land of the Ozbeks. How many backs did it break? In what is Transoxiana, That, by the way, is an ancient name for lower Central Asia. And then he continues,

the plague increased and spread further. But of course, as we'll discuss here, you know, this was a time during which there was no germ theory of disease. This bit from alardi Uh comes close to capturing the feel of an actual pandemic. But there's obviously something lacking here, and it would be lacking for some time in human attempts

to understand the Black Death's origins. Now, Suspen points to German medical historian JFC Hecker, and he writes in eighteen thirty two of it extending out of China, but he links this to a number of alleged events in this part of the world around thirteen thirty three, things like earthquakes and locusts um a falling meteor, and he then goes on to discuss it in very much the sort of context of miasthma theory. He describes it as a quote, a progressive infection of zones both above and below the

Earth's surface that sweeps east to west. So again, not an understanding of something that will travel from person to person or via rodents or any any you know, anything like we know now, but rather a kind of bad air fall out sweeping across Eurasia. And in the absence of other types of explanations, you could see how that would make a lot of sense. I mean, it could pretty neatly match the observed history of the progression of

the disease. Yeah. Now, Susmen eventually concludes that the Black Death might not have visited China or India during the fourteenth century, And then again, I mean, we can't say with degree of certainty. He just says that it seems like this might have been not in the case, though it would hit China and India in later centuries. UH. There's a great deal of European focused material on plague as well as a tradition of saying that it emerged in China, and it seems like the third plague pandemic

of the eighteen hundreds may have begun there. But it's it's hard to trace the second plague pandemic, the Black Death with accuracy. UH. European and Middle Eastern UH epidemics can be traced to Crimea in thirteen forty six, but before that, UH, it's it's hard to say. Accounts vary from in or near China to the Mongolian step to Central Asia. I've seen Kurdistan and Iraq brought in brought up in an older paper I think from ninety seven

by Norris um. So at any rate, it remains disputed, though you'll find science headlines, especially from around twenty say things like the origins of the Black Death traced back to China. Gene sequencing has revealed, but in this they're tracing it back two thousand years to the region, which is accurate would position it as the cause of the Justinian plague more specifically, and when they what they ultimately say in that study is in or near China, which

covers a wide area of Asia. But again you'll often find write ups of plague where they'll say, oh, it originated in China, or originated in Mongolia, or it originated in Central Asia. Um. And, like we said, that's one of the things about diving into into research of the Black Death is you go into it thinking that there are certain like like really just just just hardcore knowns. Some there's some solid pillars in this house of research, and and some are, but some are not nearly as

solid as you think. You know, Rob, the whole reason you brought this up with so we could talk about religious responses to the second plague pandemic. We haven't even gotten there yet, and I think we might have to call episode one right here and come back and dive into those religious responses in the next episode. I believe so. But we're off to a good start. I think we've we've we've we've highlighted what the adversary is, and the next we'll see what the religious authorities did and tried

to do to deal with it or or allowed or permitted, etcetera. UM, so it should be. It should be a fun discussion, all right. In the meantime, if you would like to write in about this episode or any other episode, do so get in touch with us. Yeah yeah. Or you a microbiologist who works with your cine a pestus, do you do you want to tell us all about it right on in? Yeah, we would. We would be delighted

to hear from you. Uh. If you want to listen to other episodes of Stuff to Blow your Mind, you'll find them in the Stuff to Blow Your Mind Podcast feed with core episodes on Tuesdays and Thursdays, listener Man on Monday, and Artifacts on Wednesday, and on Friday's we do a little Weird how Cinema. That's our time just to talk about a particular weird movie, and then we run a rerun over the weekend. Huge thanks as always

to our excellent audio producer Seth Nicholas Johnson. If you would like to get in touch with us with feedback on this episode or any other to suggest a topic for the future, just to say hello, you can email us at contact at Stuff to Blow your Mind dot com. Stuff to Blow Your Mind is production of I heart Radio. For more podcasts for my heart Radio, visit the i heart Radio app, Apple podcasts, or wherever you listening to your favorite shows.