Ideas - Rats: Facing Our Fears, Part Two

Episode Date: August 8, 2024

For millennia, rats have been portrayed as violent and disgusting. But rats have aided in our self-understanding. IDEAS contributor Moira Donovan investigates the contributions rats have made to humanity and whether co-existing with rats means coming to understand their role in our ecosystem. *This episode originally aired on October 27, 2020.

Hey there, I'm Kathleen Goltar and I have a confession to make. I am a true crime fanatic. I devour books and films and most of all true crime podcasts. But sometimes I just want to know more. I want to go deeper. And that's where my podcast Crime Story comes in. Every week I go behind the scenes with the creators of the best in true crime. I chat with the host of Scamanda, Teacher's Pet, Bone Valley, the list goes on. For the insider scoop, find Crime Story in your podcast app. This is a CBC Podcast. Welcome to Ideas. I'm Nala Ayed. Today, part two in our series on rats, an animal whose omnipresent existence is largely because of us.

Rats really are one of the invasive species most tied to human movement. And the global rat population, again thanks to us, is soaring. They can now be found in almost every corner of the earth. I think that they really are our sibling animal right now. Rodents, including rats, make up nearly half of all mammals on earth. I was looking at some stats on rat demographics recently, and the rise in the rat population over the 19th and 20th century is tied to the rise in human population.

And they increase it roughly the same, because as we make more people and build bigger cities, we create more of a habitat for them. And I think that that's just fascinating. Just absolutely fascinating. And that's not the only thing fascinating about these creatures. Even though many of us fear rats, Willard!

Willard! Willard! Willard! Remember this cult horror classic. This is Willard. And these are his friends. My God, look at the rats. But our fear is misplaced. Rats are rarely aggressive towards humans. And for those who study rats, to know them is to admire them. They are highly enterprising.

They are intelligent as animals go. They are manipulative. You know, they don't quite have the opposable thumb, but they have a lot of what it takes. Rats' noses can sniff out tuberculosis and landmines with greater accuracy than human technology. And their survival skills are second to none. They can gnaw through cinder blocks, tread water for three days straight, and squeeze through a hole the size of a quarter. In laboratories and in the alleys and sewers of our cities, rats have a lot to teach us about what it takes to make it in this world. That has been humbling to me, that I can look to a rat for wisdom. And I'm not saying that to be, you know, cute or anything. Behavioral neuroscientist Kelly Lambert.

Really, they are teaching me about what brains respond to and how you always need to be vigilant about what's going on in the environment around you to make the most adaptive responses. Because if something changes in the environment that is incredibly important to our survival and our well-being, we're likely to miss it if we're not being attentive and present. to miss it if we're not being attentive and present. Researchers say that in order to control rats, as our cities grow, our world warms, and our garbage piles higher, we need to consider rats as animals in their own right and to try to see the world from their perspective. You have to think, what would a rat do? You have to think like that to study it and to try to manage these populations.

And while rats can spread disease to humans, their role in laboratory studies has dramatically improved our health, both physically and mentally. Rats, then, we owe our respect to that mammal we actually do owe great thanks to this group of mammals radis and mus the mouse those two you and i here as as human beings you owe a tremendous amount of thanks to these animals that we've used to benefit our lifespans, our health, because we've studied these animals extensively. So they're actually the most important mammal group to Homo sapiens than any other mammal group. But the irony is, you know,

most people make a face when you say rats, when they should say, yep, you know, we owe a lot of thanks to those mammals. We are so much better because of those mammals. But yet, we dismiss them. Ideas contributor Moira Donovan brings us the second and final part in our series on rats. It explores the contributions rats have made to humanity and strategies for a more peaceful coexistence. We're calling this program Facing Our Fears.

Here we meet again in a standard city alley. This city, like many in the world, is growing denser and more populated all the time. And more people means more rats. New York-based urban rodentologist Dr. Bobby Corrigan has spent many hours in alleys and cityscapes just like this one. And while rats are good at hiding just out of sight, he says they leave all sorts of clues to their existence.

BOBBY CORRIGAN, So if we were walking down a street in a city expecting to find rats or actually knowing where to go to see the rats, I would be walking down a sidewalk, for example, and I would start looking at very simple things very quickly. For example, I would look at the city's litter baskets that I'm walking by and how full or how empty are they? What kind of litter baskets are they? Are they the type that would be difficult for a rat to get into or would it be quite easy and they just run up the side of it? So right there, a simple litter basket that people walk by and never pay any attention to in my world is a critical factor in managing rodents and cities I would also as I'm walking by I would my eyes go to the bases of

everyday doors we all come in and out of doors many times in the course of a week starting with your own dwelling is how does your own front door look is there a gap below that door if If the gap is there, I'll measure it. I want to see, can that allow for a rat skull to fit below that gap, which requires 12 millimeters, for example. As I continue to walk, I'm going to look at the foundations of every building I'm walking by. As we walk, we're going to be looking, is the foundation kept in good repair? Foundations support buildings. Over time, they break, they crack, they create holes.

People put pipes through them and cabling through. I want to look and see if there's any holes or pipes or anything leading through that foundation or any part of that building. And if so, once I get close to that hole, then I begin to look for, well, as rats come and go from the holes in our buildings, they have to squeeze. And when rodents squeeze through holes, they leave their grease from their fur. They can't take showers and they don't use shampoo. So as they squeeze through those holes, they leave these, what's called sebum, S-E-B-U-M, which is the same oil, you know, off of our own

mammalian skin. So you'll see that sebum on the brick or the cement or the wires into those buildings. So you have to be a little bit of a detective, quite honestly, a rat detective, because most people have no idea of what to look for. But the easy one, as we continue to work, that I'm going to be looking at the ground for is, of course, fecal material, right? Again, rodents and mammals, rats and mammals, and so they must eat and they must get rid of their waste just like all of us. So they produce fecal pellets, a very fancy term in science, right? Some people call them droppings. So because they drop so many pellets, so they ended up being called droppings. When a rat leaves a dropping, it's very obvious. It's usually a black pellet, a quarter of an inch,

and just lying about on sidewalks and next to buildings and in the dirt and so forth. The average rat we know as we walk about, it produces 45 to 65 droppings in 24 hours. Day in, day out, day in. If you have a family of rats all doing that, you just do a little bit of math and you see it should not be hard if rats are active in the area where we're going down the street as to finding those droppings. Part of the reason rats themselves are so hard to spot is because they're hiding from people. They fear us as much as we fear them, maybe even more. So I ask Corrigan if we're wrong to think of rats as aggressive.

Is the aggressive word used with them overblown? I would say it is. By the popular media, quite frankly. You know, if you look at the scientific literature and you study their behavior through the scientific literature, you'll see that around us, for the most part, they're never aggressive. But these facts haven't spared rats from being portrayed as fearsome and diabolic in lore and literature. As rats have haunted humanity's footsteps, they've become, as George Orwell describes in his classic 1984,

the stuff of literal nightmares. Here's an excerpt from a film version of that novel, in which Richard Burton's character gives a chilling account of rats' evil intentions towards humans. Have you ever seen a rat leap through the air? They will leap onto your face and bore straight into it. Sometimes they attack the eyes first. Sometimes they burrow through the cheeks and around it. Sometimes they attack the eyes first. Sometimes they burrow through the cheeks and devour the tongue. Burrow through the cheeks and devour the tongue? That doesn't sound pleasant.

Or true. Take Corrigan's experience when in graduate school, he moved into Barnes to study rat colonies. And I slept on the floor with them for weeks. And so I could learn as a PhD student how they behave and what they do. In general, rats try to avoid us as much as possible. We're big. We're a big predator. We can kick them. We can hurt them. And we do all kinds of things to them. So in general, they try to stay away from us. I personally have never, ever been attacked by rats, never. And I've

put myself right in the thick of those animals, as thick as I can get, including when I was an exterminator saving money for college, I worked in sewers and I had rats all around me in sewers. Never once did they attack me down in the sewers. But rats are a problem. They're highly destructive, spread disease, and their numbers are soaring globally, right under our noses. Corrigan says we haven't put enough resources into dealing with this chronic issue. You know, we don't have a lot of researchers clamoring to get into rat management. If you go to a social party, and I'm speaking, you know, from my own life, but from friends and what have you. If you go to a social party, you know, some type of party, you can imagine where people are standing around, chit-chatting with wine glasses

and making small talk. And everyone says, what do you do for a living? Let's just say you have a young 20-year-old aspiring student to be great in biology. It just doesn't sound so great that they say, you know, I want to study the control of rats in cities. Or I want to study the ecology of rats in sewers. You know, it's looked upon as it's vermin and it's low and yuck. Why would you want to do that? But if you say, you know, I want to study right whales off the coast of Nova Scotia, everyone's going to be, oh, that is so cool. I want to talk to you about that some more. So it's this human condition of we categorize mammals according to silly ways, right? In fact, as a young man, Corrigan had no intention to study rats. I thought I was going to be Jacques Cousteau. That's what I started out to do, is I wanted to

fall off boats and swim with the whales. But I had no money going to college, so I answered in the newspaper to be an exterminator in New York City. And sure enough, where did I end up? Sewers. I ended up in sewerswers killing rats in sewers and on one hand I'll never forget I thought this is a horrible job this is ridiculous what are you doing and my parents and everybody's like what kind of a job did you take you're climbing into sewers to kill rats this is disgusting but after a while I, I started looking and I said, you know what? I see a lot of intelligence down here in the sewers. I see rats swapping information with each other. I see the way they went. And the more I read, the more I studied, and I kind of fell in love with like,

listen, this is really cool. I don't care what anyone thinks. And from there in graduate school, I just said, I want to study rats and as a pest. And I had a great advisor that said, if that's what you want to do, passion is going to drive your studies. You should do it. Corrigan graduated with a PhD in urban rodent ecology from Purdue University. But even now, there remains a dearth of scientists studying rats in the wild. However, the opposite is true for studying rats in laboratories. But this is to benefit a deeper understanding not of rats, but of humans. Nearly half of all lab rats descend from albino rats bred in the early 1900s

at a facility called the Wistar Institute in Philadelphia. These days, we have rats bred to research a multitude of conditions, from rats that spontaneously develop leukemia to hairless rats for studying skin tumors. But where rats might be most useful is the light they shed on the human brain. I'm Kelly Lambert, and I'm a behavioral neuroscientist at the University of Richmond in Richmond, Virginia. And I have been working with rodent models, what we call preclinical models, maybe to learn more about biomedical conditions of humans. I've been working with rodents for over three decades, and I continue to learn from them every day.

Roughly 95% of all lab animals are either rats or mice. As for Lambert, her preferred rodent in the lab? Well, since this documentary is about rats, the answer likely doesn't come as a surprise. Rats engage in more complex cognitive behavioral responses than mice do. So a majority of biomedical research is done on rats and mice, but in the past 20 years, 15, 20 years, it has really, the mice have taken over the rat. So there are a couple of issues there. Research is expensive. Physical space is expensive. Mice are smaller as opposed to rats. They're bigger. They eat more. They poop more. We kind of got on this train of using mice more than rats. But it's important to know your species and to make sure that the species you're using is a representative model of what you're trying to model and understand. So I would absolutely come down on team rat when we're looking at behavioral neuroscience, cognitive complexity, those types of behaviors.

A bigger question is, OK, this is a rat. It's not a human. What can we even learn from a rat? And of course, in the book, I write about that. The book Lambert just referred to is called The Lab Rat Chronicles. A neuroscientist reveals life lessons from the planet's most successful mammals. On a general level, they have all the same brain parts that we have. It's just a very scaled down. they have all the same brain parts that we have. It's just a very scaled down. Our brain is about 1400 grams.

Their brain is two grams, but it has a cerebrum and a cerebellum and a brainstem and a hippocampus. If you look at a neuron, a brain cell and a rat under a microscope and a brain cell neuron in a human, you can't tell the difference. It has all the same structure. They use the same neurochemicals. It's a very good scaled down model of a mammalian brain. And it engages in behaviors that I'm interested in, stress responses and parenting and learning. I'm not studying

religion or politics and things like that. So it wouldn't be the best model for that. But some of these basic motivation related behaviors, they don't have language. Sometimes I think that's a good thing. They can't tell me why they did this instead of that. They don't have a cover story, as I say, in the book. So I have to be a better detective at trying to figure out what their behavior means. It keeps it a little bit more objective for me as a scientist. In terms of behavioral science, lab rats have brought insights into areas such as our emotional resilience, triggers for addiction, and the role of play. Lambert says one thing that stands out for her is what female rats have to teach us about parenting,

such as recent research out of her lab on how mothers cope with reduced resources. out of her lab on how mothers cope with reduced resources. So we had what we call a low socioeconomic status group, where we gave them only, instead of having two inches of that corn cob bedding in the cage, we had a half an inch. But it still had the same cage, still had soft bedding or that bedding, food, water, temperature, everything. And then instead of of two paper towels we gave them one half paper towels they had 25 of the bedding 25 of the resources in the sense of nesting material and i thought no way is that going to have any impact because

it's pretty much the same thing uh in my in my human mind it didn't seem to be that. So we have studied the moms when they have their pups in those environments and studied the pups that are being raised in that environment. And we've already known from Michael Beeney's research, who's in Canada, the attention that mother rats give their pups, it's incredibly important. That contact, we have high-licking rats and low-licking rats, and the high-licking rats have more emotional resilience and brain complexity and such. So the moms and the low resources, they did seem to be a bit disturbed and distracted. They did not group their pups as well and such, but we started to follow the pups. So they still had their mom around. They had all the food and water, everything, except it was a

little bit, you know, the 25%. And so we're looking at things related to the brain. And my very, my wonderful postdoctoral assistant at the time, Molly Kent, she was getting measurements of their bodies and she was marking their tails. And she started to notice that one group, the impoverished one, she kept marking her arm, which meant she had a motor memory of how long that tail was. And when she got to the impoverished ones, it was a shorter tail and she was going overshooting that. And she said, Kelly, I think their tails might be shorter. OMG, I don't think about rat tails, but let's measure them. So we've done two or three studies and the animals in that low resource environment, they have shorter tails. And so we're collaborating with someone who's bioengineering and they're doing scans, bone scans, and the vertebra and cartilage and the tail and then the foot.

And it's significantly shorter and more porous and more dramatic differences in this physical body of an animal whose experiences were different than anything else I've looked at in the lab. And when we think about humans, okay, this is a rat that's not very aware of worrying about whether or not she can pay for her rat pups to go to college or insurance or anything like that. Has all her needs met? There's no danger in that area. We didn't expose, we have exposed to predator, but not in this. And that is happening at a profound rate, the whole physical growth of this animal. Just think about how that stress is different for a human mother who has maybe less than 25% of the resources in whatever our ideal world is. And on top of that is worrying about no insurance or

whether or not food's going to be on the table the next day or crime in the neighborhood or college for the kids or education and just blow that out of the water with the pandemic. And now they're trying to do homeschooling for their kids and they don't have Wi-Fi connections and they don't have the food that was provided by the schools. So we really need to pay attention to the resources that are available to parents, mothers, but humans are bi-parental so that we don't have an incredible extra layer of stress. don't have an incredible layer extra layer of stress that can have a huge long-term impact on the the physical growth but also the long-term stress responses and and predispositions for you know later psychiatric illness and such so you know it's not that these animals and to our knowledge they didn't grow out of that. And you may say, well, who cares about a tail?

But that's a physical difference and it's used for balance and temperature regulation. And maybe it's a luxury to have a long tail, but maybe in the wild, it's really important to have a sufficiently, you know, a certain adequate length of a tail. So stress early on can have a huge impact. And it would be hard to kind of disentangle that. We are doing that with humans. And certainly there are studies showing that low SES leads to brain differences and such. But we can disentangle it a little bit more with these controlled environments. And we need to realize that I don't think we're getting close

to tapping in the severity of the stress and uncertainty and anxiety that human mothers and parents with this wonderfully complex brain that is making all these contingencies and trying to figure things out. The impact is so dramatic. So that gives us a responsibility. As I tell my students, now we need to be thinking about social policy and what some of the things we've learned from the rats can inform ideas about child care and providing resources for moms and such. So it's very humbling to get those types of lessons from a laboratory rat. But Lambert says the insights we draw from rats, though profound, are also limited by their standard living conditions in the lab.

Small, plexiglass boxes. If we're putting an animal and its brain in a very limited shoebox size cage. And that's what the regulations are. That's the way we have to keep these animals. They're safe, they're fed, they're taken care of, but it's boring. So I'm worried about the limitations of the environment that we have these very adaptive, clever animals in, and that may be limiting some of the findings that we have. So my more recent interest since writing the LabRite Chronicles is to look more in the wild, looking at wild rats, trying to bring technology to the field, and also bring the fields and natural environments to the lab. I write about looking at enriched environments and such. So,

we need to make their environments more complex if we're really trying to figure out what's going on in a complex brain. So, I think we've been a little bit simplistic on that front. We are really compromising the data we get from the smaller, and let's not even call them standard. It's not standard. What is it standard for? It's an impoverished environment. Let's just call it that, or overly simplistic environment. It's not standard for any rat out in the wild. If that is compromising our data, then we need to really look at that.

Lambert has put rats in cages that allow for more travel. Two plexiglass boxes attached by a tube, creating a more natural environment for the rat. And this could allow for more accurate data to emerge. We need to really look at that and what is the next step. So maybe something like this rat loft or they have an element of travel. Even though there's really nothing different to do between the upstairs and the downstairs, they're kind of busy going up and down. Part of the reason that neuroplasticity, well, neuroplasticity, the production of new cells occurs in this area

called the hippocampus. It's involved in spatial learning and memory and emotional processing. But Gerhard Kempermann, he's a wonderful neuroscientist in Germany, and he has written that the hippocampus may be involved in new cells primarily in travel and an animal's ability to go to a new territory. That's huge. Rats have done that very well. They have gone where we go. They map it out. They figure it out. They adapt. They survive. And that's another reason I really love to study them. They are opportunistic mammals like humans are. But I think we've taken all the opportunistic and what brains are good at by keeping them in these laboratory environments.

And that has limited what we can find out. environments, and that has limited what we can find out. And I'm very passionate about this because we have made no progress in finding effective therapies for psychiatric illness. We're still dealing with drug models that were introduced 50 years ago, that the efficacy rates are disappointingly low. We need to do better. And if we're going to invest all of our research dollars and time into these animals, we need to make sure the environment is representative of an environment for these animals so that we can truly, we don't want to measure lung output or function by looking at rats or lungs that are exposed to low oxygen environments because they don't have the fuel and the nutrients that it needs to function normally. Experience is the fuel, in addition to glucose and oxygen, for brains.

They don't just develop in a vacuum. Experience molds our brains just like an artist, you know, does this great piece of sculpture. So we're probably going to have to step up with the way we are housing animals, at least in the biomedical areas related to psychiatric and mental health, if we're going to get representative models that are translatable to humans, which is the true goal of our research. You're listening to part two of Rats. We're calling this episode Facing Our Fears. This is Ideas.

We're heard on CBC Radio 1 in Canada, across North America, on Sirius XM, in Australia, on RN and around the world at cbc.ca slash ideas. You can also find us on the CBC Listen app and wherever you get your podcasts. I'm Nala Ayed. My name is Graham Isidore. I have a progressive eye disease called keratoconus. And being I'm losing my vision has been hard, but explaining it to other people has been harder.

Lately, I've been trying to talk about it. Short-sighted is an attempt to explain what vision loss feels like by exploring how it sounds. By sharing my story, we get into all the things you don't see about hidden disabilities. Short-sighted, from CBC's Personally, available now. Let's return to part two of our series on rats. It's presented by Ideas contributor Moira Donovan. In this episode, we're talking about rats, how they've shaped human history and their role in our future.

For millennia, rats have caused destruction. In the United States, for example, rats cause an estimated $19 billion worth of damage every year. And conditions of the 21st century are likely to make our problems with rats even worse. Rodentologist Bobby Corrigan. Unless there's some big epizootic, a disease that kills them all in cities, there's going to be worse rodent problems in our cities in the future.

Corrigan says as our cities grow larger and denser, rat populations will follow suit. And add to that, climate change. In North America, we've had the highest temperatures in all history in the past 10 years. Well, warmer temperatures, less severe winters are strongly in favor of reproductive success of Norway rats in particular. in favor of reproductive success of Norway rats in particular. If they can eke out just one more litter or even have a slightly increase in their survivability, those are the numbers. When you have a species like this that end up in logarithmic growth, so that's just one factor is, you know, as temperatures warm up and the winters become mild, will the rats benefit?

The answer is yes. The second thing we have to keep an eye on is there's more people. There's more human beings. And the simple one there is more human beings means more trash and more density of human beings, more stress on the infrastructure. And the cost of just keeping up and things like, well, we need a bigger sanitation department, so we have to raise taxes. Well, that's not popular. Sometimes we, as a species, we wait. We wait and we wait until disaster strikes before we do anything to correct it. So I like to remind people, for example, that there's been

several very important publications in the past couple of years, some of which I'm involved with, where we have found that these rats are carrying very dangerous viruses. In fact, rats do carry part of the coronavirus group. Luckily, they're not carrying COVID. However, they do carry viruses, and we know this. So what are we waiting for in terms of controlling rats? Let's just say the rats of a city, your city, my city, they have a virus that's jumped, and now it's very, very lethal, like COVID, not COVID. We are going to do whatever it takes to get rid of those rats in that city, which isn't too difficult, actually, we could do

it. But right now, we just seem to be ho-hum, no diseases yet killing us from rats of a major area. I mean, we all know bubonic plague, but that's not going to be the disease since it's a bacterium. But it could be five years, 10 years, 100 years or 500 years, we don't know. But it could be a very lethal virus, just like COVID-19. The answer is absolutely. This has happened before, a pandemic instigated by rats in the modern era. It began in the Chinese province of Yunnan in the mid-1800s and would go on to kill 12 million people around the world. This plague pandemic kicked off as people were starting to understand the relationship between bacteria and the plague,

thanks to the work of Alexander Yersin and the Institut Pasteur. Prior to these discoveries, of Alexander Yersin in the Institut Pasteur. Prior to these discoveries, rats in places like London were not seen as the disease vector. People in Victorian times, or early Victorian times, up until the 1890s, believed that rats are exceptionally free from diseases.

And not only that, but that they were really good as kind of ways of cleansing sewers from disease. That's what people believed at the time. So not only were they not associated with plague or other diseases, but they were believed to be kind of good for public health. This is Christos Linteris. I am a medical anthropologist at the University of St. Andrews in Scotland, and I'm the principal investigator of a well-funded project called the Global War Against the Rat and the Epistemic Emergence of Zoonoses.

Zoonoses are any disease or infection that can jump from animals to humans. Of course, the rat being the first animal that was so intensively studied as a source of disease for humans, created many of the notions we have today about zoonotic diseases. The discovery in the late 19th century that rats spread disease meant that the fight to get rid of them became even more urgent. These methods included rat catching. That was the obvious thing to do. Rat catchers pre-existed. The third plague pandemic, of course, there is a long history of rat catching in different countries across the globe.

But during the third plague pandemic, this became, if you want, industrialized. It became massive. Officials in Europe and the United States widely encouraged practices to rat-proof structures, such as constructing the foundations of buildings in an L-shape. Scientists did studies of how the rat digs, or the geometric angle of how rats dig under buildings and they found that if you create an l-shaped concrete adhesion to your foundations with a particular length and width etc etc then the rat would hit that concrete l-shaped slab and think that there is a floor all across

and would not attempt digging again further away so as to get under. Now, of course, we have to say here that rat-proofing did not only take place in Europe and the USA or Argentina, etc. It also took place massively in the colonies, where the colonial authorities did not give a choice to the colonized of whether to rat-proof their buildings or not. Rat-proofing took very violent forms, such as raising down entire villages and forcing them to be rebuilt with new and completely alien material, for example.

And this with no regard whatsoever to the symbolic importance of specific material or of the specific way of building houses, you know, in given cultural or religious contexts. It was very violent, very violent interventions involved in the name of rat-proofing and as part of rat-proofing. Rats were also a threat because of their ability to hitch rides in the hulls of ships. And that's when fumigation to kill rats came into the picture. And that led, unfortunately, to the discovery and development of a very efficient gas in killing rats in the hulls of boats. A gas which was much more dangerous for those operating

it because it was hydropsealic gas but more efficient in the killing of rats and unfortunately this gas was Zyklon B. It's the gas that was then labeled within Auschwitz. So that's kind of part of plague or anti-plague technologies are linked with the history of Auschwitz, which is something we had not realized when we started researching. So technological developments in rat control led to the use of these devastating chemicals against humans in the Holocaust. Another legacy is conceptual, Linteris says, and that deals with the way we've come to blame

animals for spreading disease without acknowledging our own role. And, you know, if you have created already a language of animal-human relations which is based on metaphors of warfare and infestation and invasion, then of course the only way you can perform against a plague of rats or an infestation of rats in parks around Notre Dame, let's say, where I have personally seen many rats, that's why I mentioned that, you know, is to wage a war, you know, and create a horrible kind of militaristic kind of campaign against the animals, right? I think we need to start, we always need to start in peacetime, as it's called, when we don't have an infestation, when we don't have an epidemic. We need to re-educate the public, we need to create new metaphors, new images,

you know, so that we can move on, away and beyond that very harmful war metaphor, which pitches humans against animals time and again. I do think that viewing rats more as wildlife instead of as pests would change a bit of how we think about rats and how we manage them. My name is Kaylee Byers. I am the Deputy Director of British Columbia's Canadian Wildlife Health Cooperative, and I'm also a recently PhD researcher with the Vancouver Rat Project. The Vancouver Rat Project was founded in 2011 by veterinarian Dr. Chelsea Hemsworth to look at rat-associated health risks in Vancouver and to examine the little-understood ecology of urban rats.

and to examine the little-understood ecology of urban rats. Early ecological research found that rats mostly stay within a city block, and our research, which has used both genetics to look at how rats are related to each other and how they're related to each other in space, and also ecological methods of trapping rats and following them where they go, is that most of those rats are indeed here in Vancouver staying within a block. They rarely move between city blocks. And so they actually are quite restricted in their movements, but at the same time, they're moving throughout the block. So while they may not move between blocks, say due to roads as barriers, for example,

they can readily move within the block. So to me, the most interesting finding from the first phase of the Vancouver Rat Project was that if you looked at rats in certain city blocks, some of those city blocks would have many rats carrying a pathogen, and then the next block over would be pathogen free, but there would still be rats. And that's important because it suggests that your risk of coming into contact with a rat carrying a pathogen. Pathogens that can be deadly to humans. Is really location specific, so it's not uniform across a neighborhood or a city. So thinking about rat movement and the scale and how we might target our approaches,

if we see that rats aren't moving much between city blocks, we might say, okay, well, in terms of pathogens, at least if we target a block in its entirety, then there's probably minimal opportunity that rats are going to be moving between blocks and taking their pathogens with them and spreading them. But there definitely seems to be some unanticipated consequences of rat management. rat management. So in our work, we found that removing some rats increased the number of rats carrying leptospira interrigans, and that's a bacterial pathogen shed in rat urine and is transmitted among rats through that urine, but potentially also through social interactions, such as biting and fighting. And so rats also live in tight-knit colonies. And if you remove some of those rats, we think that what might happen is that you change the social dynamics of those individuals. If you remove some dominant individuals, that might change the social hierarchy and maybe increase fighting and

biting that wasn't occurring before. And so when you change those social structures, you can potentially change the interactions among rats and also then change opportunities for pathogen spread. Byers has also studied the societal and psychological impact of living with rats, especially on marginalized populations. So as part of my thesis research, I interviewed residents of Vancouver, so specifically residents of Vancouver's downtown east side. And so through this work, what we found is that residents were interacting with rats regularly, often in very close contact, and that those interactions elicited fear. They elicited feelings of hopelessness because of the constancy of seeing rats and a seeming lack of

effort from those deemed responsible for actually controlling them. So in that respect, seeing rats was a symbol of general neglect from the people who might be addressing other issues in that neighborhood, such as homelessness, for example. So the constant seeing of rats was sort of a reminder that nobody was doing anything about them. In other words, rats often go hand in hand with poverty and inequality. Rodentologist Bobby Corrigan told us earlier that rats are not aggressive, but there is a slight caveat in places overrun with rats. Are they occasionally in scenarios where they are aggressive on human beings? The answer is yes. For example, we have a global problem right now, as everyone knows, with homeless. And it's very sad and it's very serious. And we have more people sleeping on the

street in parks and alleyways and in building nooks and crannies. And they're forced to gather their own foods out of garbage cans and dumpsters. And so those human beings, when they lie down to sleep at night, have food odors on their clothing and on their fingers and on their faces. And rats foraging in those areas, which alleyways, and of course they are not aggressive on those people. They just smell like food. And a rat has learned, being Mr. Adaptable to explore that smell coming from, say, a sleeping person's face. Secondly, you know, we do have cases,

unfortunately, where rats will move into our buildings and they'll live in the walls. And if there's children in those buildings in bedrooms and they go to bed and perhaps a typical mom might give them a bottle of milk in the crib with them and let them, you know, suckle from the milk while they go to sleep. If a rat comes out of a wall in that child's bedroom, they will fall their nose to the milk and that will be the child's face and that will be the child's hands. And they will bite to get at the milk. So it's a case where inadvertently, inadvertently, rats, quote, will be aggressive towards us and feed on us. Kaylee Byers says improving housing to prevent rat infestations would go a long way to solving the rat problem in general. Right now we are so focused on

just eliminating rats themselves and eliminating them from our cities without acknowledging that rats are a part of our cities. They're part of our ecosystem and so I think instead of focusing on well let's just remove all rats everywhere because rats are incredibly hard to manage and we're mostly probably going to be disappointed when we try and we fail. So instead, let's think about what are the vulnerable aspects? Where are those interfaces where we can actually develop and deploy management methods to mitigate those risks? These could include everything from rat-proof garbage cans and legislation protecting tenants' rights to rat-free environments to urban planning practices that keep rats out of new structures.

But the transition to peaceful coexistence is a complicated one. And as humans develop new tools for rat management, including tools that could allow humans to edit rats out of existence, the temptation of eradication could become even harder to resist. And that raises all sorts of ethical issues. My name is Natalie Kofler. I am a molecular biologist by training and now work exclusively in the space of ethics and regulation of new technologies like genetic technologies. Kofler is the director of the Editing Nature group.

technologies. Kofler is the director of the Editing Nature Group, and one of their concerns is the ethics around genetic modifications that can be passed down to subsequent generations. When it comes to rats, the goal is eradication. Gene drives could be used to collapse rat populations through modifications such as a mutation that only allows male offspring to survive. This is particularly appealing on islands, where invading rats have helped create a crisis of biodiversity loss. That's prompted everyone from the Royal Society Te Aparangi in New Zealand to the international NGO Island Conservation to consider gene editing as a tool to save native species from rats. Kofler says there's a risk such an approach could have devastating impacts beyond the intended target. So you could see it as being a really ethically permissible action if you look at it

from a perspective of sort of restorative justice, meaning that, you know, many of these invasive rats have been brought to these islands because of human activity, whether they were stowaways on shifts or swam over from other human populated islands. So in that case, you could see that eliminating the rat could be ethically appealing because you're sort of trying to correct human induced damage, right? And so I think there's some warrant to that. But I think where it becomes, again, concerning to me is if the point is to be improving environmental conservation, then we need to make sure that the measures that we're taking are in no way going to further put those ecosystems at risk. I just feel at this point in time, we don't know enough about how these J-drives might work, what certain negative consequences could happen for us to make those sorts of decisions that might not have enough humility and precaution. yes, gene drive could be, you know, once it's deemed adequately safe and there's been adequate conversation and deliberation on the technology, could be deemed as one important tool in addressing biodiversity loss. But it needs to be done in conjunction with a variety of other measures

that we know work to help reduce biodiversity loss, including habitat protection, reducing pollutions, you know, trying to tackle global warming. And that's something that's brought up a lot, particularly I noticed more at sort of the international level, that this can in no way be sort of a band-aid solution. I also think that this is part of, again, back to like our Western dogma around the human relationship with nature and just this sort of obsession that we have with hierarchy, right? And we see this all the time that these different species are kind of put along, put on these like value system hierarchies of how, which, what we value more. I mean,

again, I think we have to be really reflective on what we value and why we value things and see how they're influenced by our cultural perspectives and make sure that we're not making bad decisions because of those values. Finding certain truths. Most living things do deserve, I think, a level of respect and to be treated humanely. And I don't know why a rat would be any different, you know, than a possum. We have to be careful about how we're making these choices. Rats are also like crazy smart and really interesting animals. So I think there's a lot to be said of also kind of broadening our perspective on these different species. And despite scientific advances, rats will likely continue to exist. Jan Zadolshevich is an emeritus professor in paleobiology at the University

of Leicester, and he says that future planetary conditions are likely to favor rats. Rats are one of the classic examples of a highly successful invasive species. So they are one of the, at present, the winners in the Anthropocene stakes. The rat is simply, if you like, the best known example, partly because we're afraid of them, but also they are intelligent, social, mobile, even sympathetic creatures looked at closely. And it's likely that whatever kind of life will arise in the far future from the remains that we leave behind in the Anthropocene, rats will figure as the ancestors of new species of the future. Zalashevich has written about this future, imagining rats inheriting the Earth

millions of years from now. If I could take a time machine and go into the far future, let's say, oh, let's say 50 million years from now, so roughly the time that separates us from the dinosaurs. They have a lot of what it takes

to deal with the kind of resources that are left. One suspects that even in a hot climate, let's say 5-10 degrees hotter than it is now in a global hothouse, partly because they live underground, they may adapt to that better than some other animals. And so I would be vastly surprised if there are not a lot of rat descendants about walking the earth. Some of them may have become as big as an elephant. Others might have re-invaded the sea yet again, you know, to take the place of the dolphins and the whales. Others may become sleek carnivores. Others may have stayed small. Some might have become even smaller. Others might be inoffensive plant eaters.

I'd be surprised if something like that doesn't happen. Having said that, I'm often surprised, but it seems a reasonable assumption to make. In other words, in a warmer, more climatically unstable world, rats may have a role in the continued existence of life on Earth. And humans, less so, if any. But there are ways to coexist, and much of that depends on improving our own treatment of the environment, which would keep rats at a manageable level while acknowledging

their role in our ecosystem. Bobby Corrigan thinks Homo sapiens are starting to understand the value of striking this balance. I do see change and I think, you know, people will begin to say, look, all mammals, all animals, the tiniest insect to the right whale, whatever it might be, they're all cool and they're all worthy of science. So I do see that change coming. I've seen just in my own world the past five years a whole lot more graduate students in rodents than I've ever seen before. Maybe this way, we will eventually lose our irrational fear of rats and stop seeing rats as vermin, but instead as part of the biosphere, a form of life as complicated by some measures as we are, and as remarkable too. Kelly Lambert I have a video of a rat risking, mama rat risking her life to carry her little offspring when there's a flood, you know, across the water.

And she could just go and be done with it and be safe, but she's carrying these animals. So they're on a continuum. They're mammals with us. So it's not just a worthless, disgusting, violent animal. To the contrary, all of that, from what I have observed. You are listening to the final part of our series on rats, called Facing Our Fears.

our series on rats called Facing Our Fears. To learn more about rats, including a video of them driving a car, or to get our podcasts or audio online, go to cbc.ca slash ideas. Ideas can also be found on Facebook and on Twitter. Special thanks to Chelsea Hemsworth and Michael Lee. Technical production, Danielle Duval and Pat Martin. Web producer, Lisa Ayuso.

This program was produced by Mary Link. Senior producer, Nikola Lukšić. Greg Kelly is the executive producer of Ideas. And I'm Nala Ayed. For more CBC Podcasts, go to cbc.ca slash podcasts.