Science Friday - Why Rats Love Cities, Science Of Saliva And Taste. May 5, 2023, Part 1

Episode Date: May 5, 2023

A Dying Planet Offers A Peek Into The Future This week, astronomers reported in the journal Nature that they had spotted a planet approximately the size of Jupiter being swallowed by a star over the course of ten days. The star, called ZTF SLRN-2020, is about 15,000 light-years away from our solar system, but still in our own galaxy. Astronomers had thought this type of planet-engulfing must happen, based on how stars evolve and certain chemical signatures they’ve spotted from inside stars. However, this is the first time the process has actually been observed. Our own sun is predicted to go through a similar expansion in about five billion years, consuming Mercury, Venus, and likely Earth. Tim Revell, deputy US editor at New Scientist, joins Ira to talk about the fate of the planet and other stories from the week in science, including mapping the trees of Africa, an experimental Alzheimer’s drug showing early promise, and reconstructing a short movie clip based on brain signals recorded in mice.   Saliva: The Unsung Hero Of Taste How good are you at tasting what you eat? Not just gulping food down, but actually savoring the flavor? When you think about how taste works, you may think about your tongue and taste buds, and how they send information about your food info to your brain. But there’s an overlooked—and understudied—hero in this story: saliva. That may sound strange, since part of saliva’s job is to help us chew, swallow, talk, and even digest. But saliva is much more interesting and complicated than that. Ira talks with Chris Gorski, editor at Chemical & Engineering News, who reported this story about taste and saliva for Knowable Magazine earlier this year.   Who Will Win The Rat Race? Last fall, New York City’s Sanitation Commissioner Jessica Tisch stood in front of a microphone and announced her plan to deal with NYC’s most hated residents: rats. She went on to make a now-viral declaration: “I want to be clear, the rats are absolutely going to hate this announcement. But the rats don’t run this city: We do.” Soon after, NYC announced its search for a rat czar. Someone who is “highly motivated and somewhat bloodthirsty” with “the drive, determination, and killer instinct needed to fight the real enemy—New York City’s relentless rat population.” This news—and the memes born from it—put rats in the forefront of city dwellers’ minds. And now, the newly appointed rat czar Kathleen Corradi’s reign has begun. But ridding cities of rats is no easy feat. It requires public participation, new policy, behavioral changes, and an all-hands-on-deck approach from several government departments. So what’s it going to take to rid cities of rats? And is it even possible? In this live call-in, Ira talks with Bethany Brookshire, science journalist and author of Pests: How Humans Create Animal Villains, and Dr. Bobby Corrigan, urban rodentologist and pest consultant. They discuss the history of humans’ relationships with rats, why these critters thrive in cities, and why we’ll need to learn how to live with them.   Transcripts for each segment will be available the week after the show airs on sciencefriday.com.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Plato. A bit later in the hour, we'll be talking rats. Yes, how did we come to live with them? And is there anything we can do about them? What do you think? We'll be taking your calls. We want to hear from you. 844-724-8255-8-4-Sci-Talk, or you can tweet us at SciFri. But first, today the World Health Organization announced that it was declaring an end to the global health emergency status associated with the the COVID-19 pandemic. Although the virus is still a threat, an advisory committee to the WHO meeting this week advised that, quote, it's time to transition to long-term management of the COVID-19 pandemic. And the WHO director general agreed saying that COVID-19 is now an established an ongoing health issue which no longer constitutes a public health emergency of international concern. We'll be talking about what that means here and abroad more next week when Dr. Anthony Fauci joins us. We'll see what he has to say about this.

In other news this week, astronomers reported in the journal Nature that they had spotted a planet approximately the size of Jupiter. That's pretty big, maybe somewhat a little bit smaller, being swallowed up by a star. Joining me to talk about that cosmic snack and other short subjects in science is Timothy Revel, Deputy U.S. editor at New Scientist. He's here in our New York studios. Welcome back to him. It's finally getting good to see you, right? Yeah, it's great to meet you in person.

Thanks for having me. You're welcome. Okay, let's talk about this. Give us the details on what happened here. Yeah, so this star snack, as you described it, this started off as a strange burst of light coming from the sky that was observed by a telescope in California. And over the course of about 10 days,

they watched this strange burst of light, and it became about a hundred times brighter. And the astronomers there were trying to work out what was actually happening. And so it looked very similar to this thing called a luminous red Nova, which is a sort of stellar explosion that happens that when two stars merged together. But it wasn't quite bright enough and it wasn't quite energetic enough. And so they ran some calculations, they took some more observations, and they worked out that what was happening was a planet spiraling in towards a dying star

that then ingested the planet into its core. And the star sort of briefly bulged up whilst this happened, becoming brighter than before, than before. And that's what happened. And that's the end of the life of this star, basically. Yeah, so it's during a process that's the end of the life of the star. So the star is sort of expanding as it goes from consuming hydrogen to helium, and in that process it sort of sucked the planet in.

Wow, this could happen to us someday, right? Yeah, five billion years' time. Set your calendar. That it's expected that almost the same thing will happen. Our star will expand. It will munch the nearby planets. And so this is the first time we've actually seen this happen in real time. And so the hope is that now we know what it looks like.

We can see it again and study it better and work out potentially what the future of our solar system is. Cool. I hope I have my college debt paid off. Let's move on to some hopeful news. There is positive news this week about a potential drug for Alzheimer's. This really is really hopeful, isn't it? Yeah, so this drug, it's called DeNanamab, and it's developed by a US pharmaceutical company called Lilly. And it's an antibody treatment. The way it works, it sort of clears some of the sticky plaque in the brain of Alzheimer's patients called beta amyloid.

And in a trial involving about 1,200 people with early Alzheimer's disease, it reduced cognitive decline by about 35% compared to a placebo. Wow, that's pretty good, is it? Yeah, so that is pretty good. and that was they measured the cognitive skills before and after a sort of 18 month treatment period. But there is some differing views as to whether, though this is a good effect, whether it's enough of effect for it to outweigh the risks. What kind of risks are we talking about? Yeah, so about a third of the people in the test group, they had some form of brain swelling or brain bleeding from the treatment, and at least two, possibly three people died as a result.

Now, we have had other Alzheimer potential dreams. drugs in the past that have not panned out, right? Yeah. So there's been a long attempt in research to focus on these beta amyloid plaques. And most of that drug development hasn't really panned out. But recently we've seen a bit of a shifting of the needle. So you might remember that back in November, there was another antibody treatment that had similar sorts of effects, both side effects and the positive effects.

And then there's also a third drug that has already actually been approved by the FDA, or whilst these other two are still going through the process. but that one has only been proven to remove the plaques, but not actually to have the impacts on symptoms. So this is a promising line of research, but it's still quite a lot to do. We'll take anything we can get at this point. Let's stay on medicine for a moment because this week, the FDA approved a vaccine for RSV for people over 60 like me.

Yeah, yeah. Yeah, well, tell me about that. Yeah, okay. So RSV, this is this like pretty common respiratory. virus and it causes mild cold-like symptoms mostly, but it can be life-threatening for older people and for very young children. And so the new vaccine, it's designed to be a single shot given to people who are 60 and over. And in a study of about 25,000 people in that age group, the vaccine was about 94% effective at preventing severe disease, which is really, really good. And so could be

available as soon as this fall. But as you say, the RSV also impacts small children. Are we working on something for them? Yeah. So there's a couple of things in the work for very young people. So one of them is a Pfizer vaccine that's given during pregnancy that is meant to confer protection to newborns. And then there's another one in the works that is specifically for infants. And both of those are due for decisions on their effectiveness and safety later this year around about August. Wow, that's another hopeful. Yeah, really hopeful on that. I'm glad you're bringing to some hopeful news.

Yeah, for the next one is also not just hopeful, but it's amazing. Scientists have made a map of every tree in Africa. That sounds like it would be impossible to do that. Very good. Yeah, this one is an amazing story. It really blew my mind when I read it. It was reported by my colleague Madeline Cuff at New Scientist. and the way it worked is that researchers at the University of Copenhagen

they took some images from satellites from a US company called Planet and then they fed them into an AI algorithm to pick out and map individual trees and the trees for them to count they had to be big enough that they were clearly identifiable as a woody plant that's how they described them in the paper and to cast a shadow but I would say any self-respecting the tree should be able to do that and then this resulted in a map of every single tree fitting that criteria across the African continent. From satellite images?

From satellites, yeah, plucked out then by an AI. I guess you had to have a shadow so a satellite could see it. Yeah, so that the AI can see them in the satellite images. And did they get a number of how many, exactly how many trees they found? Yeah, so it's in the region of about 25 billion. 25 billion? Yeah, and what makes it particularly interesting is like the distribution of some of these trees that we didn't quite understand the picture of before.

For example, they found that about 30% of trees in Africa aren't in forests, and that's compared to a significantly lower number in Europe where a similar study has been done. So it's like trees in urban areas, farmlands, and savannas. And that really helps sort of tell the picture of where trees are on that continent. Wow. Who would have thought? Yeah. In archaeology news, I understand you have a story about identifying the wearer of an ancient pendant. Yeah. So this ancient pendant is a 25th. thousand-year-old elk-tooth pendant. And what's amazing about it is that researchers have managed to extract DNA from it. And this is something that has sort of long been hoped that people would be able to do for

ancient artefacts like this, but has been very difficult. So artifacts that are made out of bones and teeth are porous. And so they can sort of absorb things like sweat, blood and saliva, liquids that contain DNA. but the difficulty has always been how do you get that DNA back out without destroying the DNA? Absolutely. So there's this new technique that is a way of extracting it, which involves submerging the pendant or the item in a sodium phosphate solution. Then you gradually crank up the temperature and then the DNA leaches out into the solution,

which you can then take out and analyze. You can't do this at home, I'm sure. Yeah, you can't do this at home. But so in this instance, what they found was this pendant. Who does it belong to? Yeah. Well, they found out that it was a woman with North Eurasian ancestry, and that matches it being found in a cave in Russia.

And so presumably she was either the wearer or the maker, or at the very least at some point, she touched this pendant 25,000 years ago. So maybe some sweat or some oil from her skin? Yeah, absolutely. Just holding it would probably be enough to do this. And where is the pendant? Can we see it as an on exhibit? Will it be returned?

Who knows? Yeah, who knows? I think at the moment it's just in a big collection of artifacts from this cave in Russia. All right. Let's move from our ancestors to human relatives. A story about apes sharing food. Is that an unusual? Yeah, that's unusual. Outside of humans, most great apes, they don't share food a lot. And so researchers were wondering, is there something they can do to sort of prompt this behavior in great apes? And so they set up this slightly unusual experiments with chimps and bonobos,

where if a chimp pulled a piece of Velcro, depending on which piece of Velcro it pulled, it could either get some food for itself or for another ape as well. And the chimps and the bonobos, they always just get the food for themselves. They don't care about sharing it. Right.

So the researchers then re-rigged the experiments so they could control whether the food was shared. And they found that when food was shared, not by the ape's initial desires, that in the next round, the apes would be much more willing to share food, with a non-rape. Wow.

And then the fun thing is they did this with some four-year-olds as well to see how willing are four-year-olds to share food. And it turns out almost the same amount of willing as chimps and bonobos. Lastly, one mind-blowing, really, research bit about reconstructing a movie clip by decoding the brain signals of mice as they watch the clip. Sounds like sci-fi. Yeah, it's very sci-fi. I mean, the sort of videos of this are amazing.

You can see mice watching a movie clip on a screen in black and white. and they fed brain activity whilst the mice were watching these clips into an AI. Then the AI had to predict for using another set of brain activity which part of the clip the mice were watching and then sort of reconstruct that movie. So they could reconstruct just from the brainwaves? Yeah, so they can reconstruct sort of which frame in the movie it was watching, which pretty amazing. Sort of a companion to the minority report.

Thank you. Thank you for that old movie. My pleasure. Thank you for taking time. be with us today. Thank you. Timothy Revel, W.D. U.S. editor at New Scientist. We're going to take a break, and when we come back, we're going to get into the science of saliva. I know it's more than just spit. You're going to find out how it plays a bigger role in taste perception than you might think. So stay with us. We'll be right back after this short break. This is Science Friday. I'm Iroflato.

How good are you at tasting what you eat? I mean, not gulping down your food, but actually savoring the flavor. When you think about how taste works, your mind goes to your tongue and your taste buds, right, and how they send food info to your brain. But there's an overlooked and understudied hero in this story, and I'm talking saliva. Now, I know how strange that sounds. Saliva's job is to help us chew and swallow and talk, and my biology teacher taught that it was the first step in digestion. But its role might be bigger and more interesting than that. Here to spit out the details, sorry, of the science of saliva. It's Chris Gorski, editor at Chemical Engineering News,

who reported this story for Knowable Magazine earlier this year. Chris joins us from College Park, Maryland. Welcome to Science Friday. Thanks, Ira. It's good to be here. Okay, Chris, what got you wondering about saliva? I mean, was your mouth watering about something, or what? I was reading these academic journals, and quite often these are pretty dry collections of prose.

And in papers, I was reading food research. writing things like, we are far from understanding the process from first bite to swallowing food. And so I'm reading those things thinking food science has been around for a while, and we've always known that there was saliva. Right. So how can this be? All right. Let's talk about chemically.

How does saliva work? I mentioned that I learned in school that saliva was the first step in digestion, but you've learned a lot more interesting stuff, right? The first thing is it's 99% water. But what's amazing about that is that remaining 1% does an awful lot to our food and our drink. Saliva is in there and any bit of food or any molecule that's in your mouth, in order to get to a taste butt, it's dissolving in saliva and it's interacting before it gets to your taste bud. Right. The other thing that's important to think about is taste and flavor, right?

Taste is sweet, sour, bitter, those things, right? And flavor is the whole experience. The smell before you start eating something, the smell that happens in your mouth when saliva is interacting with the food and then moving into the back part of your nasal cavity and you're still smelling it. That's happening too. So saliva is sort of a mediator then. It could change our experience about how we taste and smell. Absolutely. Absolutely.

And so when you drink soda, if it's bubbly and fresh and all carbonated, you are getting an interaction that's happening between your mouth, the bubbles, the sugar in the soda, and for a long time, researchers have thought that there was like an acid happening in the soda, and that is perhaps why if you let that soda flatten out, sit in the counter for a couple of hours, it might taste sweeter when it's flat, but why is that? Well, you know, we think if there's, you know, no more bubbles, the carbonation, which makes it acidic would be gone, right? So you wouldn't have it tasting acidic. Right. There were some researchers who decided to investigate that with an artificial mouth and they put in saliva and they

tried to figure out what was going on. What they saw was that bubbles themselves got between, well, they blocked up the passageway where the sugar molecules would have been going to the taste buds. So if you've got bubbles, it might taste less sweet, not because of the acid, but because there's a physical blockage happening and stopping the sugar molecules from getting to your taste buds. They use an artificial mouth with an artificial tongue here. Yeah, yeah. I think that was another thing that I learned about was the way that the texture feelings in the mouth depend on saliva as well. You might have a yogurt that's been thickened up so that it looks like a full fat yogurt when you pour it out. But your tongue can tell the difference. Your tongue can tell that the same

amount of fat is not there because your saliva and the fat interact and lubricate everything. And that's where you get that really satisfying feeling that happens if you eat an ice cream or a rich yogurt. Yeah. What about saliva and smell? I know the taste and smell are intertwined. We've talked about that. Does spit affect what you sniff? Well, it does once the food or the drink is in your mouth. As you bring no glass of wine to your, to your lips, it's not going to. going to do anything. You're going to have that initial sniff, right? But once you get the wine in your mouth and swish it around a little bit, molecules in the saliva, mostly the proteins, that will grab on to different molecules and influence how they get to your retronasal passages.

So how that interaction happens in the back of your nose is definitely influenced by your saliva. Well, if I'm a professional wine taster, then would I have more saliva because I'm good at this? you know, and that's one of the reasons why maybe I can taste it better than you can. Yeah, so there was a study from Spanish researchers who found that volunteer tasters who produced more saliva tended to score the flavors of wine as more intense. It seemed to be that maybe that was because they swallowed more often and were forcing more aromas into their nasal passages. We started out talking about your interest in saliva. Is there anything we should study about saliva that you'd like to know? Well, so a couple of things. One is, can you make foods healthier, but give the same

satisfying experience of a chocolate or an ice cream that's going to taste just as luxurious as it's like full fat, full sugar counterpart, but just not have all of those molecules in it? How do you make stuff without all that stuff in there? It tastes like it has it in there, I guess is what you're saying. Well, there was a researcher who, Enmishad Sarkar, who told me about this, and she said that perhaps they can work with what they know about saliva to move the kind of important fats and sugars to your tongue and facilitate that movement. And because they figured out how to capitalize on that, they wouldn't have to have it, those sugars and fats throughout the whole food in an even way. They could just make sure that they were getting the ones that gave you that experience to your tongue.

Final question to you, Chris. You've done a lot of reporting. on this, do you now approach food differently or tasting differently now that you've learned all this stuff about saliva? You know, I haven't thought about it that way. What I've thought about is how grateful I am that I am able to have this all happening in the background of my mouth that I didn't even realize what's happening. And that's the whole joy of it. You don't have to think about it. You just have to do it. Yeah, yeah. And even when I look at my kids and I think I'm lucky that they're not particularly picky eaters, but the idea that someday somebody might be able to use some of these insights and figure out a way to make, you know, bitter foods, your broccolies, your, your

cales, provide an additive that might make kids' experiences with those foods a bit easier to take so that they can eat healthy foods. I think that'd be great, too. Chris, thank you very much for taking time to be with us today. Thank you. This was a lot of fun. Chris Skorski, who is editor at Chemical and Engineering News, based in College Park, Maryland? And it you want to put your saliva to the test, we wrote up a fun experiment for you to try at home. Visit sciencefraiday.com slash spit. Sciencefriday.com slash spit. Are there any critters more resilient, scrappy, impressive, and hated than...

Little rat. That's right. Hate him or not. Rats are all around us. These resourceful rodents are really good at not just surveillance. surviving, but thriving, almost anywhere we are, right? And that makes getting rid of them really hard. Cities like New York are fed up, and the mayor's office is ready to go to war. The rats are absolutely going to hate this announcement. But the rats don't run this city. We do.

That's what you think. But do we actually, because rats have been around us for millennia, and it's going to take a lot to get rid of them. But I'll give you a hand. hint. Doing so starts with us. We assembled our own rat pack to talk all things rats. Let me introduce them. Bethany Brookshire, science journalist, an author of pests, how humans create animal villains, joining me from WAMU in Washington. Welcome back to Science Friday. Hi, thanks for having me. Proud to be Rat Pack. And Dr. Bobby Corrigan, urban rodentologist and pest consultant, joining me right here in our New York studios. Welcome to Science Friday. It's great to be here.

Nice to have you. Bobby, you've been studying rats for decades and have become a real legend in pest control, I understand. As pesky as rats can be, what is it about them that you admire? You know, it's an incredible mammal, and when you look at it, started in Mongolia, pretty much spread around the world. And so what I admire about them is, you know, they're able to get the job done. No matter what we throw at them, they're able to adapt to it. you know, they're not an animal that, you know, is going to complain, if you will,

about having the same meal over and over again, and they make the most of taking advantage of all the nooks and cronies in all our cities. Well, if we've waited your appetite, maybe a bad way to describe it, and you want to talk about rats? Give us a call. Our number is 844-8255-8-4-Sy-Talk, or you can tweet us at SciFRI. Now, since you've been doing this for so long, I'm sure you've seen some real adventures, had some real adventures, studying rats.

What's the wildest thing that's happened to you? You know, it's true. You do, they take you on an adventure. For me, I've been in sewers, for example, below old cities. Crawling through those sewers, the other name for the noir rat is a sewer rat. And so I see that animal in sewers. I see them at the surface level in all different kinds of basements and ceilings and so forth. But for me, I think back, the most adventurous is chasing them through the sewer systems.

Can you describe the picture for us? Well, you know, most people can appreciate a sewer is not a pretty place to hang out, you know, and you have a flashlight, you're in dark, and it's quite smelly, as you can imagine, and it's wet below, and every once in a while you'll feel this furry thing scurry by, you know. And so it's the definition of mysterious, yet at the same time, frightening. How did you overcome that fear? It took a while, but I have to tell you, the first time down in the sewer or the first time down in the basement, knowing his rats all around me, my heart was pounding. You know, it was full speed ahead, and I didn't know what to expect.

But doing it more and more and more, as years went by for research and for experience, gradually, I realized these rats are not going to attack me. they'll scurry away, but if I leave them alone, they're going to leave me alone. Bethany, you went on a field trip with Bobby when you were writing your book. What did the two of you do? Yeah, sadly, he did not take me into the sewers. I want to go next time. No, he took me on a wonderful rat safari where we got to hang out in a bunch of the parks in Manhattan and look at some of the rodent control efforts that they were trying out.

there. It was really amazing because once you start seeing signs of rats places, you cannot unsee them. And you realize they are everywhere. Well, you wrote a whole book that I loved about pests and your, and our relationship with them. When did our relationship with rats start? I mean, our relationship with rats started actually before the brown rat, really, which is the Norway rat, the sewer rat. It started probably, we think, with the black rat, which, um, came out of India and started spreading around 8,000 years ago. We actually, the brown rat didn't really kind of come into Europe and certainly not to North America until the 18th century when we know that we started seeing large amounts of brown rats.

And they kind of displaced the black rat in a lot of places. So, for example, it's probably only brown rats that live in New York. But brown and black rats both live in places like Los Angeles where the weather is warm. So there's a couple different species that you'll see around, but probably in New York you're looking at brown rats. This is Science Friday from WNYC Studios. We're talking rats. So much to talk about here. Let me go to the first tweet that came in, speaking of New York City, visited New York City and a cat-sized rat ran between his legs, Bobby.

Well, it was cat-sized. It probably was a cat that ran between his legs, you know. Is that a myth? It is a myth. Everybody loves to say the rats in our alley are big as alley cats, and everyone holds out their hand like giant fish stories. But the average rat, even a large rat, is going to weigh perhaps one pound, six ounces, somewhere in there.

There's no two-pound rats, and there's no rats that are going to get as big as certainly as alley-cats for anything like that. It's actually to their disadvantage to get much bigger because then they can't dart away and dart down small holes. and escape into the shadows. So we're not going to have these super big rats. So why are rats so good at living in cities then?

Well, it's, you know, the cities have billions of interstitial spaces in all kinds of basements, below the streets. You know, we have pipes of all different types, not just sewers. We have abandoned pipes that have been there for 200 years, you know, but they can get it done. They can live in ceilings, walls, bushes in the earthen burrows. So it's successful because they do it all is kind of the way it is. And we have a lot of food for them, don't we?

Yes, we do. And every year of a city with a lot of people, you know, somewhere I read with the experts saying 20 to 25% of the people are very, you know, they spill things, they drop things. They don't use litter baskets correctly. So the rat has no shortage of opportunities for finding a tidbit to eat. Bethany rats, as we have been saying, are easily one of the most. hated critters out there. In your research, why are we so averse to them?

If they don't seem to be they leave us alone, like Bobby says, if we leave them alone. Yeah, I mean, I ended up actually going down a big research rabbit hole around the science of disgust, because people are often afraid of rats, they're afraid of being bitten, but really

the major emotion you get is disgust, right? And it's because disgust is one of the basic emotions, right? We have basic emotions like joy and anger and disgust. And disgust is one of those emotions that specifically is about getting things that might make you sick away from you, right? So think of the face that people make with disgust, which by the way, this face is universal, the bleh face, that face. Sometimes the sound is included.

Look at your radio. Yeah. Yes. And that face is associated with trying to get something out of your mouth. So that sense of disgust doesn't seem like, you know, we're not eating rats, except there are some cultures where they do eat rats. But, you know, we don't usually think of it. But disgusting things are things that might cause sickness. So feces, for example. And then you have rats that are in sewers with the feces. Pretty soon, disgust gets transmitted to the things that are associated with things that might make us sick. But Bobby rats leave behind some of their droppings, right? They do.

You know, the research is shown the average adult rat can defecate into pellets 45 to 65 times every night. You know, and it's not true that they don't have bladders. They do have bladders. It's not true that they can't control their urine. They certainly can control the urine. But they are defecating and urinating pretty regularly wherever they go. Wow, wow.

Bethany, you said you talked about some places where the rats may not be public enemy number one? Where might that be? Yeah, there are a couple of places around the world. One of my favorite examples is the Maori who live in Atearoa, otherwise known as New Zealand. And they brought the Pacific rat, which they call Kiori, to New Zealand when they actually came there. And it was part of their food package. And they still really regard the rat with a lot of respect.

All right. We're going to take a break. We have so many phone calls. We're going to get to them 844-724-8255. Still some room for you to call, or you can tweet us at SciFri. Stay with us. We'll be right back. This is Science Friday.

I'm Ira Flato. We're talking rats with Bethany Brookshire, science journalist, author of pests, how humans create animal villains. Dr. Bobby Corrigan, urban rodentologist and pest consultant. He's here with me in our studios. is our number 844-8255. You can also tweet us at SciFri. Let's go to the phones to Craig and Houston. Hi.

Hey, how's it going? Go ahead. Hey, yeah, I'm on my third generation of rats. They live about three or four years pet rats. Also, in Cambodia, rats have been trained to detect landmines. There are ways that rats can be helpful in society, and they're friendly creatures. I promise you, they are friendly.

If given to their own druthers, they potty train almost themselves and are very clean. They spend a lot of time grooming. In fact, that's how they show dominance within a pack of rats is by aggressively grooming each other, which is wonderful to watch.

Bobby? Yeah, those are great comments. And, you know, it's very true. It's an animal we really have to admire for everything you just mentioned. You know, it'd be great if they would stick to their own territories, for example. And as Bethany mentioned, you know, unfortunately, when humans use food and we discard it and what have you, we draw them a little bit too close to us if they're coming out from beneath a dirty dumpster with lots of germs and bacteria.

And even though they're great mammals, it's probably in a city environment. We don't want to get too friendly with them and getting too close or proximity with them. Thanks for calling. Bethany, when you did your research, did you find that people were defending rats? I mean, certainly there are people who have rats as pets. I actually, when I got my author photos taken, I got to pose with one of my friends' rats, and she was lovely. Her name was Magrat, and she did not poop or pee on me at all the entire photo session, so A plus to her.

I know a lot of people who respect rats. You know, they're used, for example, in laboratory research and biomedical research, and they have contributed amazingly to human health and to the health of other animals. So, yeah, there's a lot of respect, but I think when you're encountering one coming out of a dumpster, it's a different feeling. Yes, and it's true. Seriously, we do owe a lot of our medications to rats who sacrifice their lives. You know, it's also worth mentioning that, you know, this business of disgust with these animals and also fear.

You know, I think if we go all the way back to imagining sleeping in a cave or a youth or something like that, and in the middle of the night you see something close to the ground that's slinking by and dragging something behind it, almost that has a snake image and it may even squeak and hiss at us, you know, as we're getting close to it. It can be a very disturbing experience to go through that. Let's go to the phone to Susie. Is it Higginham, Connecticut, Susie? It is. Hi, go ahead.

Hi. So I have rats living under my house, and I tried trapping them. I got one adult and one baby that I relocated last summer. After that, all I got was squirrels, birds, and chipmunks. So I found this, I don't want to kill them. I found an herbal birth control. that I give to them every three days scattered on some food

but I'm seeing little ones now so it's not working 100%. And my friends all think that they're going to chew up my wires and destroy my house so I don't know what to do at this point. Bobby, is that correct? Well, you make a very important point and that is, you know, chew up the wires.

You know, the word rodent actually translated means to gnaw. And so a rodent's an annoying mammal and they do like to gnaw on wires, and they can cause fires and shortages. So it is important that you don't allow any rodent, squirrels or rats to live below your house for that exact reason, as you mentioned. The best advice would really be call in a good professional in your area, and they have the expertise to come in and live trap and remove those animals. If you do not want them killed, that can be done.

You just state that service, and that can be done. That's the best way to approach that. All right. Good advice for you. Susie, good luck. Okay, thank you. Yeah, I have discovered in my backyard. I have a lot of rodents, as you mentioned, that they chew on your barbecue wires.

Yes. Because if you leave the grease inside, right? Definitely. You know, clean your barbecue. They go after that, and then they say, hey, some wire here. Yeah. Sometimes wires are also look like vegetative stems. So they're, forget the pun, but they're hardwired to be attracted to that shape, that

linear long thing, looks like a stem. When New York City published this job posting for its first rat czar, remember that few weeks ago, it went viral because it became a pop culture moment of its own. Bobby, did you think about applying over that job? No, you know, a czar, a governmental czar is someone that's great at organizing things, getting parties together, forming plans, and this kind of thing. But I'm a rat scientist, not an organizer or a plan. and this kind of thing.

But I think it's great that the city of New York took that step to actually spot the importance of having a czar that's going to get everybody organized. But the Ratsar has no experience in pest control, I understand. I'm not sure they would necessarily have to, although they're going to go through, you know, fast course and what it's all about and already have, and it's biology. And so, you know, their czar is trained in biology and so forth. I think they're off to a running start. All right.

Let's go to David in Pittsburgh. Hi, David. Well, maybe we... David, are you there? Yes. All right, go ahead. Hi. Hi there.

Hi. I have not heard you mentioned that brats harbor fleas, which can be very dangerous, carrying bubonic plague and things like that. I think brats were implicated in the Great Plague. Yes, David, it's true. They carry ectoparasites, you know, fleas, mites, and, you know, ticks, these kinds of animals.

And so from that aspect, it is important, you know, not to have them again close to us because it may not be the rat themselves that transmits a particular pathogen. It could be a flea. You know, and so in general, the rat being close to human beings is not a desirable situation. Bethany, managing trash, it seems to be, is key here. Yes. Because we leave it out. I mean, aren't we as guilty as the, you can't blame a rat wants to eat something to eat?

right? Get something to eat. I mean, if you're going to leave Thai food sitting on the corner like that, of course. Who wouldn't? Yes, I think, you know, the rats are, you know, as Bobby said, the big issue is going to be managing people and a lot of that people management is managing the sanitation in New York City, you know, trying to get rid of those piles of black trash bags that pile up on the corners every single night. Let's go to Cecily in Cambridge. Hi, Cessaly. Welcome to Science Friday. Oh, hi, thanks for having me on. I just wanted to talk about the fact that it's critically important to consider the impact of rat control on raptors, on hawks and eagles and owls and other wildlife. They're the natural predators. They're the natural pest control,

and they're being poisoned at a really frightening rate. Where I live in Cambridge, Massachusetts, you see poison, it's out of control. You see black bins in every yard. I've counted a hundred bins placed along an avenue when a town is doing utility work. And what happens is the poison accumulates in the tissue of the rats. And a weakened dying rat is an easy prey. So bird watchers and park goers here saw, for example, a family of great horned owls that raised and swore. pledged two owlets, and then the whole family was poisoned, found having bled out. These are anticoagulants, so they bleed internally, bleed to death. An eagle was recently found just a couple of weeks ago who people had been watching.

She was getting ready to nest. She was found on the ground, rushed to rehab, impossible to save her. 90% of red-tailed hawks who are brought into the Tufts Veterinary Clinic here have these escars, these anticoagulant rat poisoned in their bodies. So this has to stop. Okay, Bobby. Yes, it's a great comment. It's a very important comment.

In fact, I think it's an ecological imperative that this is addressed. Right now, the Environmental Protection Agency is studying the issue, detail is to look further as to what intense restrictions are going to have to be implemented against these second generation anticoagulant redenticides, escar, as you mentioned. So this is fully queued up right now and there's a lot of attention on it. It's too bad. It took so long, quite frankly, but for sure changes have to be made in the use of these redenicides, for sure. What is the best way then? Well, quite honestly, the best way, Ira, is what's called integrated pest management and that means as bethany stresses in a book and other and others is you don't feed rats these

are mammals if there's no food there's no rats and if you reward rats by them coming to your property just because one of your garbage cans are sloppy they know that reward they come back to that same spot over and over and over again so the best place is sanitation is rat control literally bethany you great um yes absolutely and i also wanted to note that the second Generation anti-coagulant rodenticides that she was talking about have already been banned in California. There's currently a ban, and they just got permanently banned in British Columbia and Canada. So that's absolutely ongoing. Let's go to Stanley in New York. Hi, Stanley. Go ahead. In Istanbul, there are no rats. There are millions of cats. Same in Tel Aviv.

Tel Aviv, there's lots of cats, there's no rats, there's no mice. I live in Manhattan, okay, mostly in Chelsea Village area. I'm up on the Upper West Side right now for another month or so. I notice the rats here are larger than the ones downtown. But I believe the only thing that really takes care of rats is cats, owls, huts. I know New York City at one time had an owl program

and I know doing hunting for rats in Central Park I know in Washington Square Park the Parks Department no longer puts out poison they find the holes, they put dry ice in the holes of the rats, it sucks out all the oxygen and the rats die below

in the ground. And if you have an apartment, there's three apartments on a floor. The apartment on the right and the left have cats. There'll be mice in the center apartment. All right. Let me get a comment. Bobby? Let me just say that this is Science Friday from WNIC Studios. So all those comments, all those techniques that we just mentioned, you know, they have a place. And that is the trick about the rat. You need a multi-pronged approach. to do in rats and cities. And once you have a city, for example, though, it's very difficult to, you know, in a city to introduce lots of predators that are going to have space to prey upon the rats. The rats conduct below cars. They conduct down a sewer. They conduct down into a wall void.

So it's not as easy as getting hawks and owls and cats and dogs and this kind of thing. Although, you know, here and there, they're all going to contribute. But once they're in the cities, the best thing we can do is maintain, eliminate the food. And where do rats live in the country? In the country. They dig rat holes? There's a word rat hole, right? That's right, boroughs.

Burrows. And as Bethany mentioned, you know, the brown rat, the rat we have in most of our cities, you know, they are burrowing species. From where they came from, they were burrowing into the ground. They construct an underground burrow of about six feet long. Nest is in the middle. They prefer to borrow in good soil. That's their natural home. But they talk, I'm sorry.

But they'll take anything. You know, they'll adapt like the hollow trees. They'll do. They'll do ceilings. That's part of their success. They will take whatever they can get. Bethany, I think it's interesting that New York City has had a rat problem forever. But this is the first czar the city has ever hired.

Why now? What's going on? Honestly, I think some of it is that now the rats are being visible to people who are of higher economic status. because people have been dealing with the effects of rats, especially people who are living unhoused, especially people who are living in public housing forever, forever. You know, there are reports that you can find of, you know, babies being bitten by rats at home while they're napping. And this was, I think, in 2018. There was a report on homeless shelters in 2015 that described them as overrun with rats.

but, you know, I think it's only when people who aren't living on public assistance start complaining that we get these problems. Has COVID people staying home, Bobby? Has COVID had any effect on the rats coming out or is being visible? COVID, especially during the shutdown, had tremendous impact on the rats. I was out doing surveys, for example, and when all the restaurants closed down and there were no bags of food, the rats pretty quickly learned where is the gravy train? And so what we started noticing, the rats were leaving the areas where the food used to be abundant and spreading out towards residential areas where people were at home and putting out their garbage.

And I suspect, although I have no empirical numbers to share, but I suspect millions of rats died as a result of the pandemic just from their own stress of fighting over the little tidbits of food that were left behind when everybody evacuated the city. Yeah, there was that iconic picture in New York of the rat with a piece of pizza going down. But they are very smart, aren't they? They are, and there's a lot of good research to show how intelligent they are. And, you know, I have evidence with my wildcams who are showing them picking up sticks to set off rat traps, then setting off the trap and getting the bait after it's set off. Toolmaker, tool users. There are tool users, good publications, refereed publications on rats using tools.

We've taught them to drive little tiny cars at Richmond University in Virginia. They did experiments where you put them in a little tiny car. They have to push the gas pedal, turn the steering wheel to get to the food. Bethany, last word? Yeah, I think we really need to appreciate rats for being the incredibly adaptable, wonderful little critters that they are, and then realize that a lot of the control issue is us. There you go. Yes, Bravo.

It's us. Thank you both for taking time to be with us today. Bobby Corrigan, urban rodentologist and pest consultant here in New York. Bethany Brookshire, science journalist and author of pests, how he's. Humans create animal villains. Thank you both. Thank you. Thank you.

And if you'd like to read an excerpt from Bethany's book, go to ScienceFriiday.com slash pests. Here are some of the people who make this show happen. Our radio producers are D. Petersmith, Kathleen Davis, Shoshana Bucksbaum, Rasha Aidi. Rasha Aidi, John Tancke, is our director of news and audio. Our radio director is Charles Berkwist, who is celebrating his birthday today.

Yeah, Day. I hope you're doing something good, Charles. Happy birthday to you and many more. B.J. Leiderman composed our theme music, and we had helped this hour from audio engineers Lisa Gosselin and Kevin Wolf. And also thanks to our friends at WAMU in Washington, D.C., for their assistance. And, of course, if you missed any part of the program or you would like to hear it again, yes, subscribe to our podcasts or ask your smart speaker to play Science Friday. A lot of folks may want to hear that rat segment one more time.

Have a great weekend. I'm Ira Plato.