Science Friday - Levee Wars, New Neurons, Animal Farts. April 6, 2018, Part 2

Episode Date: April 6, 2018

The mighty Mississippi is shackled and constrained by a series of channels, locks, and levees. The height of those levee walls is regulated by the Army Corps of Engineers to ensure that riverside districts equally bear the risk of flooding. But some districts have piled more sand atop their levees to protect against imminent flood risk during emergency conditions—and then left those sandbags there after the danger passed, leaving a system of levees with irregular heights. A team of investigative reporters at ProPublica has shown that those higher levee walls protect the people and developments behind them, but shift the risk of flooding onto neighboring communities who have followed the rules. A new study reported in Cell Stem Cell this week found evidence of new neurons and their stem cell progenitors in brains as old as 79, some with numbers of neurons on par with younger brains. Columbia University neurobiologist and study author Maura Boldrini describes the work, and why we’re still resolving questions about aging brains. Not all farts are created equal—some animals don’t have the affinity for flatus, while others use their stench strategically. Zoologist Dani Rabaiotti and ecologist Nick Caruso, authors of the book Does It Fart? The Definitive Field Guide to Animal Flatulence, discuss how there really is much more to flatology (the study of flatulence) once you get a closer whiff.    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 John Dankoski. Ira Flato is away. A bit later this hour, which animals get gassy the way humans do and which fail to flagellate. Yes, we'll cut through the stinky science of animal farts. Really, coming up later. But first, the Mississippi River was once free to meander, flowing where it pleased, doubling back, slicing shortcuts and forming oxbow lakes. If you look at a map of its historic channels laid on top of one another, it looks like a tangled bunch of strings. But then, we came along and we shackled and constrained the river in a series of dams and locks and levees and channels, forming a river that's much straighter and much faster than before. That kind of engineering requires agreement among regions that for everyone's benefit walls be built to certain heights to spread the risk of flooding around equally, and that is regulated by the Army Corps of Engineers. But some districts haven't abided by the rules. They've fortified their levees, they've piled them up higher with sandbags, which could push floodwaters over to their neighbors elsewhere on the river. They're lobbying the government to keep it that way, too.

It's the topic of an investigation by the nonprofit news site ProPublica, and one of the reporters is here with me now. Lisa's song is a reporter at ProPublica. She joins us in our New York studios. Welcome, Lisa, to Science Friday. Thanks for having me. If you live along a levy and you want to weigh in, you can call us 844-724-8255. That's 844 SciTalk, or you can always tweet us at SciFri.

Let's start a bit, Lisa, with the science part of your investigation. Communities are breaking the rules, and that's putting others at risk. Explain what's happening here. So what happened was a year ago, the Army Corps of Engineers did a survey of hundreds of miles of levee in the Upper Mississippi River.

And what they discovered was about 40% of those levees, about 80 miles, had been overbuilt by 2 to 4 feet. And that meant that these local levy districts had raised their levees by 2 to 4 feet without getting the proper permits from the Army Corps.

And so they were basically breaking federal rules that are in place to ensure that different communities are treated equally and that one community isn't adding extra flooding to another community. Yeah, and talk a bit more about that, adding extra flooding to another community. I build my levees higher. It means you might get flooded. Right. So when a river is flooding along, when water is flooding along a river, it's going to overtop or flood the sort of weakest chain link in the chain, right? And so if your community is behind a lower levy, then the water is going to come and you are going to be at more risk. And so that means that if everyone just starts building their levy as high as they want,

then those towns with the least amount of resources or that don't have the ability to raise their levies, they're the ones that are going to get flooded worse. And it's not just that they're getting flooded. They're getting extra floodwaters they wouldn't have gotten if their neighbors had followed the rules. I can imagine a lot of public officials saying, look, I've got extra funds in my district, and I want to protect my town. So what's the problem with building my levy taller? What's the issue here? Well, you would set off a sort of chain reaction, right? And that's what people want to avoid is what's called levy wars or a levy arms race, where everyone is racing to have a slight advantage over their neighbors. And that's obviously not fair, particularly for

communities that don't have the resources to keep raising their levies. Another important thing to remember is oftentimes when you raise your levies, you have to make the base of the levy wider, and sometimes there's just no space for that. So there are other constraints. And that's why we have federal and state regulations. Yeah, and the Army Corps of Engineers is involved with this. They've been surveying this levy system. What did they say about all this? Well, you know, they had been hearing anecdotes for years before they did the survey of people saying, we think our neighbors have raised their levies illegally. You know, we want you to do something about it. And that survey was the first widespread, you know, case where they actually had real answers. And they were able to show that

all of these levies had been built higher than they were authorized to go. I want to bring on another guest now. A river detective who hunted for evidence of old Mississippi floods, he came up with the conclusion that all our engineering is partly to blame for making flooding worse. Sam Munoz is a geoscientist and assistant professor at Northeastern University in Boston. He's the author of that study in the journal Nature. And he joins us from WBUR in Boston. And Sam, welcome to Science Friday. Hey, thanks for having me. So your study examines the human impact and human engineering on the lower Mississippi River.

You found that all this engineering is contributing to more severe flooding events. Tell us more. That's right. So what we did was we were interested in looking at the, we were interested in looking at the history of the river. And so what we did was use sort of what we call natural archives, in this case tree rings and sediments from lakes. And what we did was reconstruct when floods occurred and how big those floods were going back over the last 500 years. And what we see is that flooding that we've had over the last century or so, both how big those floods are and how often they occur, the river is flooding more today and those floods are bigger than it was in the previous four centuries. Yeah, and how exactly do you know that?

So you're finding evidence in the sediment. What else you learning as you're doing this examination? Right. So we're finding evidence and sediment and tree rings. So you can imagine that you have an oak tree that lives near the river in the floodplain. But most of the time, it's not getting soaked. It's not getting flooded. And so it's pretty happy most of the time.

But then every now and then the river rises and it inundates part of the floodplain where that tree is. And that tree is unhappy. It gets stressed. And so the growth ring in that year will show what my colleague, Matt Therrell, at the University of Alabama calls anatomical anomalies. So at a cellular level, you can see that this tree is stressed. And so what he was able to do was basically collect these cores of trees in the floodplain and reconstruct years in which we had big floods in the Mississippi.

And the other sort of piece of this was using sediments, lake sediments. And so you mentioned in your intro that, you know, you have, if you look at the Mississippi today, there are all these sort of scars on the floodplain of evidence of the river moving around. So what we did was actually use those scars. We would go to them. They're called Oxbow lakes. They form because the river moves around. We'd go to those lakes and a boat, and we'd basically vibrate a 30-foot-long aluminum irrigation pipe into the bottom of that lake. And that gives us this record of when floods occurred because when the river over-trial, tops its banks, it'll leave sediment, it'll deposit sediment in that lake and leave a sort of layer

marking the passage of that flood. And so that's how we're able to look at the history of this. So how exactly do you know that it's humans, though, in the way that we are engineering around the Mississippi River, how do we know that that's what's causing the problem? Right. So what we were really interested in was first looking at, you know, can we use these archives to reconstruct floods? And I think we can. And then we were really interested in understanding what are the natural controls on this river. So we can now, with this record, we're able to go back to a time in which human impacts on the river and the basin are pretty minimal. And so then we can look at what's the natural variability of the river and flooding

on the river and what controls that. And what we found is there are these, you know, what you might call climate cycles controlled by the Pacific and the Atlantic Ocean and that those are really controlling how often the river floods and how big those floods are. But then what we see is, I mentioned, there's this sort of increase in the last century or so of how big those floods are and how often the river's flooding. And we just can't account for that based on our understanding of the climatic controls on the river. And yeah. Well, so it seems, Lisa, as though from your reporting what the Army Corps has looked at, what Sam's looked at on the lower Mississippi, that this human intervention, that the building of levees and more construction around the river

it's caused more flooding. The second part of your investigation looked into some of the politics and in their districts that have been lobbying the federal government to loosen restrictions on levy building. So with all this data, all this information, they still want to build higher levies. Yeah. And it's actually some of the same districts that have been shown to have overbuilt their levies without the correct permits. Instead of complying with the federal rules, their solution so far seems to be to hire lobbyists, go to Washington, D.C., and try to convince Congress to pass a law that would reduce the Army Corps' ability to regulate levy heights. So they're trying to get out of it by just removing the existing rules that are in place. And this is obviously something that is

being pushed by the local officials who run these levy districts. So it's a local issue. Is it also a national partisan issue, too? It doesn't seem to be as partisan because the people who run levy districts are all local officials and they're the ones then going up the chain and lobbying their state and federal officials. So we haven't found such a clear partisan issue. You know, I think if you're a state representative or federal representative, you are trying to answer to your constituents. And so it becomes a very localized issue. Okay, so Sam, there's another part that humans may play here. How does climate change come into all this? Is this boosting some of the problem in the Mississippi? We don't really know.

That's clearly a really important question, and it's sort of astounding that we don't have a great answer to how climate change is affecting flood risk on the Mississippi. The best study that I'm aware of, and I may wake up tomorrow to a really angry email saying, why didn't you talk about my study? But the best study that I know of came out a few years ago, and they basically took a bunch of climate model output

and posed it on a model of the Mississippi, and under a bunch of different scenarios, they basically concluded that average flow on the Mississippi will increase under greenhouse forcing under anthropogenic climate change. But that's just looking at average flows. And as far as I know, we don't have a good handle on how extreme flows, how floods, will actually change with climate change. We just have a little bit of time left.

Sam, are there any new innovative solutions being proposed right now? Anybody thinking about solving this problem differently? Yeah. And so, you know, there are plenty of ideas out there. One that has been used successfully in the Netherlands with the Rhine River was actually they did build their levees higher. They take into account the effects of climate change. And they actually move the levees further back from the river to basically let the floodplain be a floodplain and let the river sort of spill out onto its floodplain, which can help attention. to insulate flooding and help us with some other issues associated with channelization.

And Lisa, is there any sense that American officials are taking a look at any of these other innovative strategies in Europe or elsewhere? There is a little bit. The Army Corps has done several levy setback projects around the country, but it's just very small and just starting out. Lisa Song is a reporter of ProPublica here in New York City. You can check out her reporting on the Mississippi. We've got links at Science Friday.com slash river. Lisa, thanks so much. Thank you. Thanks also to Sam Munoz. He's a geoscientist and assistant professor at Northeastern University in Boston.

Thank you, Sam. Thank you. This is Science Friday. I'm John Dankowski. It's well known that as we age, our minds often change. Our brains can slow down. We have less plasticity and abilities to learn. Our emotional regulation can be affected as well. For a long time, the explanation was the neurons. We just aren't. growing new ones as quickly as we used to, and it's certainly the case in mice and non-human primates anyway. But some researchers have been finding evidence to the contrary, and a study published this week in the journal Cell, Stem Cell, finds that, in fact, the oldest brains in the sample showed just as much evidence of new neuron growth as the youngest, 80-year-olds, on par with

teenagers. My guest is lead author of that research. Mora Baldrini is a research scientist in neurobiology at Columbia University. Welcome to Science Friday. Thanks so much for joining us. Hi, how are you? I'm doing well. So what do we know for sure is happening to our brains as they age? Yeah, so the story has been changing, right? And when I went to medical school, they still used to teach that the brain doesn't make any new neurons in adulthood. And then slowly we started seeing from rodent studies that this was actually happening.

And that's why I decided at this point more than 10 years. years ago to start looking at this in the human brain. And Colombia seems like a perfect place to do this because they had been collecting brains from people who donated after that for decades. And so we started looking at neurogenesis in the human brain. And there was a seminal studies in 1998 in Northern Europe that showed that they could find new neurons made in the brain. They use the technique that is very much used in mice to use a molecule that gets incorporated into the DNA as the cell divides and then figure out that this cell was

actually becoming a neuron. And this were people that unfortunately were going to die. They were patients who had cancer and then they donated the brain after. But this was a study that could not be replicated for obvious reasons. And these people were not young. They were in their 50s and in their 70s and not healthy, and those neurons were there. So there was another study recently, fairly recently in science from Karolinska Institute, who found a method to basically establish the age of neurons in the brain, that were collected after autopsy.

And they found that according to their calculations, probably we make 700 new neurons per day in each hippocampus. This region that is very important for memory and for emotional responses to stress. And they found that this was true even in people who were older. At the same time, there have been other studies like the very recent study on nature that didn't find any new neurons in our older brain. Well, and I just want to stop you on that really quickly.

And I want to ask why it does seem to keep changing. I was going to ask you about this study from nature. It came to almost exactly the opposite conclusion. So why this variability? Why do we keep to keep going back and forth on this idea of whether or not we grow new neurons? Well, so neurogenesis changes or the making of neurons in adulthood, basically, it changes very much depending on the condition of the person. It's known that pathology changes neurogenesis.

So the people who were analyzed in the paper that came out in March, basically they don't have clinical information on those people regarding pathology at the time of death or medications on board at the time of death if these people were taking medication or they were on ending drugs. The brain collection at Columbia is different because we perform extensive clinical evaluations including interviewing families and close contacts and reviewing the charts. So we are very interested in studying suicide, the depression, and the effect of treatment on the brain. So we are at the same time excluding the diagnosis in people that are going to become controls for our studies when we want to study these pathological situations.

So in our sample, this time that we chose for the aging study, we selected those. We demonstrated no neurological, no psychiatric diseases, no medication, no drugs. So these were clean brains from people who died and they were healthy aging individuals. Those individuals that end up dying of sudden death, accidents, myocardal infarcion, but they were not cognitively impaired. And we all know somebody in the 90s that is super sharp, right? Age doesn't have to come with cognitive impairment. Sure.

Well, but then what happens if indeed your results are correct and we are growing new neurons, what is happening to cause the cognitive impairment? Is it something else about the brain that is not connecting these neurons even as we're creating them? Yeah. So we didn't study the people with cognitive impairment, and that's definitely a next step. What we found in these normally aging individuals is that one specific protein that is related to some plasticity events in the brain,

like this protein, it's expressed when the neuron makes new connections, or when migrates. in the region or when grows the branches that reach other cells. So this protein was in particular a little less expressed, found in fewer cells or in fewer new neurons in this region, and also we found less vascularization of these regions. So as though we still find the same number of new neurons, but it could be that they are supported by less vascular, fewer capillaries, and maybe less plastic. So even though these people were not affected by any dementia or memory problems, there is some vulnerability that comes even with normal aging.

Maybe the reaction to stress or to sudden changes can be more difficult when someone is older or sometimes there is some emotional vulnerability that comes with aging, that even when there is no real disease or dementia. We just have a minute left. I have to ask you what you see as the practical application of some of your findings. I mean, do you believe that some of what you're working on now may allow us to understand how we can be sharper at an older age, how we can continue to have brains that are functioning very, very well,

into our 90s and beyond? Yeah, so for people with normal aging, I would suggest that we know that these neurons are supported by aerobic exercise, by learning, by environmental enrichment, exposure to social situations and interactions. So we wouldn't want older people to be isolated. We would want them to be active, engaged in things that are interesting to them, try to learn something new every day, exercise. And also on the clinical side,

I would want to compare my findings with findings that I could find in brains of people who actually had connoisseed decline and dementia of different sorts and figure out what changes in those brains. And we know that there are molecules that regulate the survival, proliferation, maturation of these neurons. And if those were changed in people with dementia, we could identify targets for new treatments. Well, that is all the time we have. It's fascinating stuff. I want to thank our guest, Mara Baldrini. She's a research scientist in neurobiology

at Columbia University, which seems to have an amazing brain collection. Mora, thank you so much for joining us. I appreciate it. Thank you very much. My pleasure. Okay, as much as we may be loath to admit it, everybody farts. You may be able to pass your flatulence off on the dog or the cat because, well, they fart too. In fact, most organisms with a fiber-rich diet and the right kind of gut bacteria can develop gas in the digestive system, gas that could be expelled in a room clearing off people. Well, not all farts are created equal. Some animals don't have the affinity for flattis. Others use their stench strategically. My next guest discovered this when they set out to write the only book you'll need on the subject.

It's called Does It Fart, The Definitive Field Guide to Animal Flatch. They join me now to talk about it. Danny Rabayati is a zoologist studying wild dogs at the Zoological Society of London. Danny, welcome to Science Friday. Thanks for joining us. And Nick Caruso is postdoctoral ecologist in the Department of Fish and Wildlife Conservation at Virginia Tech. Nick, welcome to Science Friday. Thanks for being here. Hi, John. Good to be here. Of course, if you've got a pressing question about animal flatulents, don't hold it in. Give us a call. Our number is 844-724-8255. That's 844-Sci Talk, or you can tweet us at

sigh fry. I guess Daniel, I'll start with you. This book has a pretty interesting backstory. How did it come about? Yeah, so it all started the January before last when I was on holiday with my family and my younger brother who was 19 at the time.

He turned to me and he was like, Danny, do snakes fart. And I'm a zoologist, so I'm kind of expected to know these sorts of things but I've never really studied snakes, so I didn't really know the answer. But fortunately, I'm quite active Twitter and I knew just the person to ask David Steen who's a snake expert on

Twitter so I tweeted him David do snakes fart and he responded super enthusiastically with sigh yes turns out he gets this question quite a lot so that's kind of kicked things off and then Nick appeared on the scene and he was like oh my goodness we're Zoologist we get this asked this all the time we should totally start a hashtag and that was how hashtag does it fart was born. And in the true nature of science, I then suggested we turned it into a spreadsheet, which we did. And then our publishers wrote to us and they were like, hey guys, do you want to turn your spreadsheet into a book? And me and Nick were like, yeah, that would be amazing.

So this is kind of how this came about. So it's a book, Nick, that's born on Twitter. I suppose we should start, though, with a definition for flatulins. You came up with a strict definition for the book. Explain what exactly in your mind a fart is. Sure. So the medical definition of flatulence is gas produced during digestion that is then expelled out the anus. While we have animals that don't necessarily have this organ or some gas may not be produced during digestion that could be air that swallowed, we decided to expand the definition a little. little bit. And so the definition, the working definition we had for the book is any sort of gas that could be gas that's swallowed or that's produced during digestion, that it's expelled

out the opposite end of the mouth. So it could be for some animals an anus or cloaca, for example. Okay, so that's a fairly strict definition on your part. I'm John Dankosky. This is Science Friday from PRI Public Radio International. And we're talking with the authors of a book called Does It Fart, the Definitive Field Guide to Animal Flatulins, because I assume earlier field guides were insufficient. Danny, in the studies that you read, how are scientists testing whether or not any of these animals farted?

Oh, there's an amazing wealth of literature out there into people studying animal farts, particularly domestic animal farts and pets. Someone devised a backpack that you can put on a cow that collects the farts from the cow into like a giant balloon. And then some people just came across them from working with those animals. We had some great stories from primate researchers, for example, who said that if they can't find their study species in the forest, particularly chimps, they can listen out for the sound of them farting

and follow them along in the rainforest. So yeah, people have devised a lot of ways of testing whether animals fart, but I think by far the common method was just listening and looking out for it. So, Nick, does a certain diet make an animal more or less likely to be a farter? Yeah, definitely just like humans, diets higher in fiber tend to produce more farts, more gas. You know, it can vary as well, depending on the animal, what their specific diet is, if they eat kind of an incorrect diet or possibly if they have some infections, that could also lead to a higher frequency of flesh. Is there anything else, Danny, that distinguishes the farting animal from the non?

I think, well, the main criteria for some of these animals is like, does it really have much of a digestive system? Some of the animals covered in the book, they don't really have much of a digestive system. So, for example, we did the Portuguese Man of War. It's lots of little single-cell organisms. And some of them are specially adapted to basically dissolve food, but they don't really eat the food. So obviously they couldn't really fart because they don't have a butt, really. So that was one of the main things. There was also a few surprising things.

If food passes more quickly through the animals, they're less likely to fart. And also, the amount of gas produced in digestion relies heavily on what microorganisms are in the animal's digestive system. So certain microorganisms produce more gas than others. So some animals were lacking in those, really. And, Nick, what kind of gases are we talking about? You mentioned cows earlier. I mean, we know cows produce methane, but are there other gases involved here? Yeah, so there's obviously, if it's swallowed air, you have the composition of air.

You could have carbon dioxide, oxygen, nitrogen, as well as if you have a protein-rich diet, you might have some farts that are heavy in sulfur compounds, which I think most people are aware of that typical, of that particular smell. And, Nick, were you surprised at the amount of real science involved in flotology? Definitely surprised. You know, I think going into it when we first were starting our research on this book, thinking, okay, you know, we're going to get the most of our information through, you know, first from people who have maybe heard or smelled a particular animal's farts. But diving into the literature, we discovered there's some scientific papers that include it. And so there's quite a wealth of information. We just have a few seconds before the break.

Same with you, Danny. You were surprised at this? Oh, yeah. There is so many scientific papers out there talking about the amount of gas that comes out of various animals. It's actually really interesting to read. I learned an awful lot just from the scientific literature and then obviously from beyond as well. Okay, so we're going to learn a lot more. We're going to come back and we're going to do a does it fart quiz.

I hope I pass. That's coming up on Science Friday with the authors of Does It Fart, the Definitive Field Guide, to animal flatulins. We're talking with Nick Caruso and Danny Rabbiotti. And this is Science Friday. This is Science Friday. I'm John Dankosky. We're talking with zoologist Danny Rabbiotti and ecologist Nick Caruso. They're now experts in flotology with their new book, Does It Fart, the definitive field guide to animal flatulins. You've done all this work identifying animals that fart, so it's only fair that you get to test us with this knowledge. So you're going to be helping us with a little quiz here. If you'd like to play along on our quiz at home, you can check it out. on our website, sciencefriday.com slash farts.

Now, we play this game yesterday with our Twitter audience, and I'll let you know how they voted during the game. Okay, Danny, why don't you kick things off with our first question? Go ahead. All right. So, John, we'll start off sloaf for the first one. The first question is, do sloth's fart? Yes or no?

Sloth. You're talking about sloths, correct? Sloths. Okay, sloths. My British accent. Ah, yes, they just. Okay, so sloths or sloths, they hang out all day. they eat leaves, their mammals.

I don't know. The evidence, I think, points to yes. I'll say yes, sloths fart. Ah, so what, what, I thought most mammals fart, what's going on with the sloth? So actually the sloth was the only mammal that we found that did not fart. We had quite a, well, I had quite a fun and lengthy time finding this out. So my first stop was I delved into the scientific literature and I found this paper. and I found this paper and it said, oh, sloths produce a whole lot of methane.

But it didn't say where the methane came from. So I was like, are they burping it? Are they farting it? I don't know what end it's coming from. So I put the question out to the internet. And someone got in touch with me and they said, oh, I work at Glasgow University. And they've just invented this camera that can pick up methane on camera. And I work at a zoo. So I was like, oh, maybe we could put a sloth in front of it.

we could find out what end the methane is coming from. And unfortunately, before this plan actually took effect and I got to do an in real life experiment, the person who wrote the paper wrote back to me and he said, oh, it's not farted out. They reabsorb the gas into their gut and they breathe it out. And this was seconded by a sloth sanctuary who said, oh, if sloths get gas in their digestive system, they're really sick, they're probably going to die. So sloths definitely don't fart.

They do kind of have farty breath, so that was a term for the books. I guess that kind of counts. Our Twitter audience, by the way, was stumped by that one, to only 7% guessed correctly. All right, Nick has the next question. Go ahead, Nick. Okay, John. Which of these water animals is a known farta? The goldfish, the herring, or the sea cucumber?

Hmm. Okay, so two of them seem pretty similar, the goldfish and the herring. The sea cucumber is an entirely different animal. I'm going to guess a sea cucumber. number. Okay, so Nick, what was the right answer? Herring is the correct answer. Okay, herring. Hmm. What a hair, how do herrings fart? Well, not only do they fart, but they use their farts for communication. It's pretty fascinating. There are, both Atlantic and Pacific species can gulp air from the surface and then

store that air within their swim bladders. They later expel that air through their anal ducks, which then produces a high-pitched raspberry sound that is very wonderfully named the fast repetitive tick, or F-R-T. Ah. Very nice. So maybe we've answered one of Parker's questions. Parker's calling from Modesto, California. Do you have more questions about fish, Parker?

Yes. How do you see when they fart? Like, because when I'm in the tub and I fart, you know, you see bubbles. So I think that probably happens to all of us, Parker. So is that how you can tell? Or I assume that you have to, Nick, find out in different ways with different fish. Yeah, that's actually a pretty common way that we found out for various animals. If they farted, it was you'd see the air bubbles coming from their end opposite of their mouth.

And so that was a good way for some of the aquatic organisms to figure it out. It turns out only about 20% of you, by the way, who played on Twitter guest, the herring was the correct answer there. The most popular answer was the sea cucumber. Are you sure, Nick, that sea cucumbers don't fart? Yes. Yeah, they're one of those animals that has a primitive digestive system. So while they don't fart, they do have some really interesting things going on in their back end. So there's some species of pearlfish that will actually live inside their cloaca.

And not only do they live within the sea cucumber, but the sea cucumber, sea cucumber, excuse me, provides it a food source. The pearlfish will slowly consume the sea cucumbers gonads as a food source. The great thing about sea cucumbers is that they regenerate those. a never-ending supply of food. I'm almost tempted to move in myself, to be honest. Okay, Danny, you've got the next question. We should probably move on.

So next up, I have a question about an animal that I think a lot of people probably won't know about. It's the larvae of the beaded lace wing, which is a small brown flying insect. And it uses its farts for something really useful. Do you reckon it is to, A, propel itself across a leaf, B, kill its prey Or C, emit a distress signal

When under attack Oh wow Okay, so, well, propulsion seems to make sense And we've heard about animals That use farce to communicate But I have to say, Danny, I really want the answer to be B I want the answer to be kill its prey

Hey, I got one right Array So what makes the fart so lethal? So the Bid Layswing, it lays its eggs near a termite nest and the larvae hatch out and they crawl in. What they do is they feed on termites. So while they're in the termite nest,

they fart out what's called an alumone and it's a special chemical that only affects termites. And what it does is it stuns the termites and then slowly kills them so that they can eat them. But the really cool thing about this chemical is it doesn't affect other insects. So in the scientific paper on this, they put different kinds of insects in there.

They weren't affected. It only kills termites. So don't worry, guys. You've got nothing to worry about from the beaded lacewing lava farts. On Twitter, 19% of our audience guessed that time correctly. Okay, Nick has the next question. Go ahead, Nick. Okay, John.

So which of these animals can do both fart and breathe oxygen using the same organ? Is it A, the painted turtle, B, the llama, or C, the humpback whale? The painted turtle, the llama, or the humpback whale, that doesn't seem like something the llama would have. But to me, I guess it makes sense that it would be a sea mammal. So I'm going to say humpback whale. Ah, I got that one wrong too. So it must be the painted turtle. Yes.

Ah, okay, so what's so special about the painted turtle? So they're able to draw in water through their cloaca, and they use specialized sacs called Bursa to absorb oxygen. which allows them to stay underwater for longer periods of time, which is, as you can imagine, pretty useful during their winter hibernation when they're burrowed in the mud. Wow, interesting. So the audience did better than I did on that one. 48% of people who played our quiz guessed the Painted Turtle. Okay, Danny, we got one last question here.

Let's give it a try. All right then. This one's kind of relevant to my research. Researchers once thought this animal's flatulence could have helped solve climate change. Is it A, dinosaurs, B, kangaroos or C, humans? So listening to the way that that's worded, it could have helped to solve climate change. I'm going to say that that's a clue here, and I'm going to say dinosaurs. All right, so dinosaurs, kangaroos, was it the kangaroo then?

It probably wasn't humans. Yeah, it is indeed the kangaroos. So researchers used to think that kangaroos didn't actually produce much methane when they farted, when compared to cows. So cows produce an awful lot of methane, although actually most of it is burped out, not farted out. And this is a really big contributor to climate change because we farm so many cows for food. So they thought that maybe if they took the micro organisms out of the kangaroos gut and they put it into the cow that they might be able to make cows produce less methane. However, sadly, more recent research found that actually kangaroos do fart quite a lot

and quite a lot of gases coming out may be equivalent to a horse if a horse was the same size as a kangaroo. So sadly, that area of research ended there. Kangaroos farted too much to save us from climate change. And our audience guessed that one pretty well. 51% of you guessed the kangaroo. You guys are pretty smart. I mean, one of the questions in there came up from one of our collars we weren't able to get to. But how about dinosaurs?

I mean, do we assume, Danny, the dinosaurs farted or no? Well, we know that they ain't fart anymore. But yeah, so we assume that the larger herbivorous dinosaurs probably did fart. We know that they would have produced a lot of gas just from the structure of their digestive system, although it's really hard to tell kind of what was in their gut, because obviously we only know from fossils. However, we know that birds don't fart, so maybe the dinosaurs that birds evolved from,

although birds are dinosaurs themselves but the ancestors of birds they probably didn't fart we don't really know where farting died out in that lineage I want to give out our phone number again because people have questions about this believe it or not 844 724 8255 or 844 sci talk we just were talking about birds and dinosaurs

Nick so so most birds don't fart why not what is it about birds well there's a there's a couple things that go against them for fart One, since they fly, you know, they don't want to keep a lot of food in their digestive system for very long because it is heavy. So food passes relatively quickly through the bird's digestive tract. And two, they don't quite seem to have the same, you know, gas-producing microbes to produce the necessary gases for a fart. And another one that we're not sure of another flying animal.

What about bats? What do we know about bats in farting? It's pretty similar. They have a pretty quick digestive system, so there may not be enough time for gas to build up and then fart out. However, if they do fart, it's likely not audible, so it's a little harder to find out.

So I think that is definitely an area that we need more research. We're talking with Nick Caruso and Denny. Rabbiotti, and they're the authors of a new book called Does It Fart? It's the definitive field guide to animal flatulence. It's a book that was born on Twitter, and a lot of people want to join our conversation as well, and we'll get to some questions in a minute. This is Science Friday from PRI, Public Radio International. Let's go to a caller here.

Esther is calling from Tallahassee, Florida. Hi there, Esther. Hi, how are you? I'm doing well. What's on your mind? So I recently became pregnant and I am flatulating a lot more than usual. So I'm curious to know if that happens with animals too, primarily cows because I know they have four different stomachs. Yeah, that's right, four stomachs.

They're eating grass all day. Thanks for the question, Esther. What do you know about, I don't know, Danny, pregnant animals, do they fart more than non-pregnant animals? It wasn't something we came across in the research, but. I know for a fact that pregnant animals tend to eat a lot more because they're supporting their offspring. So I can imagine that more food in means more gas out. So yeah, I would say it was pretty safe, but the pregnant animals probably do far out, at least a greater quantity of gas. We're getting a lot of questions from Twitter, Nick, about bugs, whether it's spiders or insects. What do we know about that? That seems unlikely that insects, for some reason, would would flatulate.

Yeah, well spiders is definitely a huge question mark. And that's something that we couldn't say yes or no definitively in the book. But there are some insect farders out there. I think most people know these particular bugs as either pill bugs or roly polis. In fact, they can emit ammonia gas out through their exoskeleton. Now it doesn't just excrete out from the rear end. it can excrete out their whole exoskeleton. But it is a really long, drawn-out fart lasting up to about an hour or so.

So there is some farting going on in the insect world. Lasting up to an hour? Yes. Oh, my goodness. Well, we have to ask, because we don't want to run out of time before we do. And, Danny, we can't not ask about the cephalopause. This is Science Friday's favorite animal. So does it fart?

No. They do not fart. Their digestive systems don't really have any way of producing gas or storing gas. So they do not fart. But they do kind of ink. But as it wasn't a gas, we decided it's not quite classified as a fart. But we were disappointed too. But they are included in the book because we love them so much too.

You guys clearly had a lot of fun putting this together. Danny, what are some of your other favorites in here? because each one of the animals has a, or most of them are accompanied with some pretty hilarious drawings as well. I mean, what are some of your favorite little bits of research in here? I think my favorite paper that I came across is for this species of fish. It's called the balsam pupfish, and it lives in these little tiny pools in Mexico. And in the summer, it gets really hot in these pools. And these fish feed on algae.

They, as many fish do, take up the sediment off the bottom and eat the algae off it. Then this summer, the algae produces a lot of gas. So the fish eat the algae. They get really bloated. They get really full of gas. And they become really buoyant. And normally they hide in the sand, but they pop back up to the surface. And they're just like really fat and really bloated.

And they're bobbing around. And they can get eaten by predators. And if they can't fart in time, then there was even some recorded cases of them exploding. Oh, no. Oh, dear. Nick, how about you? Did you have any favorites in all of this? I think that one may have been one of my favorite illustrations.

I think the dinosaur one as well. And just to give a quick mention to the person who illustrated the book, Ethan Kosak did a fantastic job with it. I think just the types of illustrations he provided for the descriptions of the animals farting is it really makes it a complete book. I have to ask you, Nick, this sort of research, such as it is, if it happens on Twitter, we're able to crowdsource all these scientists and people. This really is a new way for scientists to talk about something in some ways funny and fun here, but also about really serious topics. I mean, this probably couldn't have come together if it wasn't for Twitter, right?

No, and in fact, you know, Danny and I have never actually met in person. So we've wrote this book primarily over email and, you know, doing Skype and Twitter. and getting input from various scientists, we know on Twitter. And, you know, we've known this ever since we started our science career, that science is collaborative. We're not able to do this alone. And so, you know, even in something like figuring out which animals farts takes a lot of input. It takes a lot of input from a lot of people. I really appreciate your input today.

Nick Caruso, a postdoctoral ecologist in the Department of Fish and Wildlife Conservation at Virginia Tech. and Danny Rabbiotti, a zoologist, studying wild dogs at the Zoological Society of London. Thank you both so much. This was great fun. Thanks for having us. One last thing before we go. Science Friday is hitting the road for Pennsylvania next month. Yeah, they're going to my hometown, Pittsburgh, the Carnegie Library Music Hall.

Saturday, May 19th, we'll have roboticists and artificial intelligence designers, lots of smart people there. Musical robots, musical humans, too, Pittsburgh's own townspeople. More information and tickets at ScienceFriday.com slash Pittsburgh. That's Science Friday.com slash Pittsburgh. Ira is back next week in New York. I'm John Dankoski.