Poop Party: Answers to your poo questions

AUTOMATED VOICE: You're listening to Brains On, where we're serious about being curious.

AUTOMATED VOICE: Brains On is supported in part by a grant from the National Science Foundation.

MOLLY BLOOM: Before we start, we want to be sure you know what's coming next. This episode is all about poop. So you might want to pause if you're about to eat.

MENAKA WILHELM: And if toilet talk makes you squeamish, maybe this isn't the episode for you.

SANDEN TOTTEN: But we know a lot of you are super interested in this topic.

MARC SANCHEZ: Yeah. We get all kinds of poop questions from listeners, and we're tackling as many of them as we can. Will it be a little gross? Yeah. Will it be totally engrossing? 100% yeah.

MOLLY BLOOM: So for those of you who dare to continue, welcome to the poo zone.

We're talking turds.

MENAKA WILHELM: We're examining excrement.

SANDEN TOTTEN: We're curious about caca.

MARC SANCHEZ: We're making number twos our number one.

MOLLY BLOOM: That's right. This episode is a full on poo party.

SANDEN TOTTEN: Because hey, we all do it.

MOLLY BLOOM: And lots of scientists study poop to learn about our health.

MENAKA WILHELM: Yeah. It's sort of like a report card for your digestive system.

MARC SANCHEZ: And when you start looking at the wide world of animal poops, things go from eww to that's so cool.

So plug your nose and get ready to party.

This is Brains On from American Public Media. I'm Molly Bloom, and my co-host today is Violet from Sunnyvale, California. Hi, Violet.

VIOLET: Hello.

MOLLY BLOOM: So Violet, we asked you to co-host this episode because you sent us a poop-related question not so long ago. Do you remember what it was?

VIOLET: Why is poop brown?

MOLLY BLOOM: That's a really good question. And I'm going to tell you, you are not alone. We have gotten many, many, many, many questions about poop. So do you think that poop is funny?

VIOLET: Depends on the context.

MOLLY BLOOM: So like in what context would you think poop is funny?

VIOLET: If it's like a joke, then it would be funny. But if it's like a doctor who found something not good in your poop, then it's definitely not funny.

MOLLY BLOOM: That is definitely not funny. Yeah. Poop can be a serious matter, which we'll talk about later in the show. So why do you think that people are so fascinated by poop?

VIOLET: I think people are very curious about it because it happens every day, and everyone does it. But no one actually tells us much about it.

MOLLY BLOOM: That is a really good point, yeah. Because it's sort of like considered inappropriate to talk a lot about poop. It's not dinner conversation, and it's not really something you necessarily talk about in school. So there's not really a source of poop information is what you're saying.

VIOLET: Yeah.

MOLLY BLOOM: Well, now we have a source of poop information. We have a lot of poop information in this episode. Let's start with the basics.

VIOLET: Where does poop come from?

MOLLY BLOOM: Your butt, of course.

VIOLET: Right. But before that, there's a whole long journey.

MOLLY BLOOM: An epic quest. It all starts with food.

APPLE: I am but a humble young Apple living on a farm I dream of one day being something more. What that is, I cannot say.

MOLLY BLOOM: That food starts its adventure in the mouth, where it's broken down by teeth and saliva. Then it's disintegrated even further by stomach acid and eventually ends up as mush in your intestines.

APPLE: It's so dark in here. I fear I may be doomed to a life of endlessly wandering these vast caves. Oh, woe is me.

VIOLET: In your intestine, that food is broken down even more. Little bacteria help eat a lot of it. And all this releases nutrients and energy for your body.

APPLE: Wait. I think I see a light ahead. At last, my journey might be coming to an end.

MOLLY BLOOM: An end indeed. When your body has taken what it needs from the food, the leftovers are pushed out with a plop.

APPLE: I'm free. And what's this? I've been transformed. Behold my glory. I am no longer a lowly apple. I am a mighty bowel movement. My family will be so proud. Huzzah.

VIOLET: Hey, Molly.

MOLLY BLOOM: Yeah.

VIOLET: Did you know some people poop three times a day, and other people poop just three times a week, and both are totally normal?

MOLLY BLOOM: Wow, where did you learn that?

VIOLET: From the news.

MOLLY BLOOM: That doesn't seem like the news I listen to.

VIOLET: Oh. You got to tune to channel number two. Sanden, Marc. And Menaka have been doing a special show there. They have all the fecal facts. Check it out.

SANDEN TOTTEN: Good evening. You're listening to Bowel Action News.

MENAKA WILHELM: Where we get to the bottom of things.

SANDEN TOTTEN: I'm Sanden Totten.

MENAKA WILHELM: And I'm Menaka Wilhelm.

SANDEN TOTTEN: Tonight's top story is from Henry.

HENRY: Why is poop stinky?

MENAKA WILHELM: Well, Henry, research suggests feces gets most of its funk from bacteria.

SANDEN TOTTEN: That's right, Menaka. These bacteria live inside your digestive system and help break down the food you eat. They make stinky gases in the process. A lot of which ends up in your poo.

MENAKA WILHELM: So basically, our gut bacteria fart a lot, and it makes our poopy stinky.

SANDEN TOTTEN: Now let's dive deep for our regular segment, Fecal Matters.

MENAKA WILHELM: Today's topic is from Elise.

ELISE: Why does our poop come in different shapes and sizes?

SANDEN TOTTEN: For an answer, we turn to poo-porter, Marc Sanchez, live in Flushing Queens. Marc.

MARC SANCHEZ: Good evening, Sanden. As you can see behind me is a row of bathroom stalls. I'm here to find out what's behind the shapes that come from our behind. Sir, Bowel Action News here. If you don't mind. Please describe your latest bowel movement.

MAN: Like a little brown snake, I guess?

MARC SANCHEZ: Fascinating. It turns out there's a scale of poop shapes developed by scientists called the Bristol stool chart. It features seven kinds of poo. Shape one involves these little pebble-like poos. Picture chocolate-covered raisins.

MAN: What? Eww. Now I can never eat those again.

MARC SANCHEZ: If you have these tiny turds, it's a sign that you might be constipated, in other words, having trouble making dookies. Moving on to shape number two. These are more log-like, but firm and lumpy. Also a sign you might be a little backed up.

MAN: Is this a real news channel, or am I being punked?

MARC SANCHEZ: No pranks here, my friend. Shape three is a poo that's sausage-shaped with little cracks in it. And shape four is like a smooth little brown snake.

MAN: Oh, like mine.

MARC SANCHEZ: Exactly. These poos look like little logs because they're shaped in your tube-like intestines. Doctors consider Bristol stool shapes three and four to be the most healthy ones. So congratulations, sir.

MAN: Oh, thank you. Can I wash my hands now?

MARC SANCHEZ: Please do. Shape five poos are little blobs with clear cut edges. These mean you need more fiber. Shape six is watery with ragged edges, and seven is just a runny mess. Both are signs of diarrhea.

MAN: Oh. That's bad. Also, I'm leaving now. This has been the weirdest interaction of my life.

MARC SANCHEZ: Indeed. Good day to you.

MAN: Bye.

MARC SANCHEZ: So the shape and size of your poo can say a lot about your health at the moment. Smaller, harder poo means things are staying too long in your bowels. And watery number two is a sign that things are flushing out too fast. This has been Marc in a bathroom stall. Back to you, Sanden and Menaka.

SANDEN TOTTEN: That's solid reporting, Marc.

MENAKA WILHELM: Truly poo news you can use.

MOLLY BLOOM: Poo is truly universal.

VIOLET: Yeah. It's not just humans. We see it all across the animal kingdom too. So we've invited some animal experts to our poo party.

MOLLY BLOOM: They'll be answering your questions, like this one.

YASMIN: My. Name is Yasmin. I am from Malaysia. My question is why are wombats poop squared-shaped?

MOLLY BLOOM: We need a second to react to this question, right? Wombats have cube-shaped poop. It's true. And they're the only animal that we know of that has cube-shaped poop. So how do they do it? It all happens in their intestines.

PATRICIA YOUNG: If you imagine the wombat intestine, it's like a long, soft tube.

MOLLY BLOOM: Patricia Young studied wombats' intestines to figure out how they make their uniquely cubic caca. All animals' intestines are a little stretchy, but there's something special about the sides of a wombat's intestines.

PATRICIA YOUNG: Some of them stretch more than others.

MOLLY BLOOM: So human intestines and most other animals have intestines that are round. And as they're stretched because of poop is traveling through, the intestine keeps that round tube shape. But when wombat intestines stretch as a poop travels through, it doesn't stretch out into a bigger round shape. The tops and bottoms of the wombat tube are very stretchy, but the right and left sides are more stiff. So when this special wombat intestine tube fills with poo, its four sections stretch differently, and that forms four sides. So as the intestine squeezes the poop down the tube, it creates a little cube. Cube-shaped poop. Ta-daa.

OK, Violet. Your listening acuity is going to be put to the test. It's time for the--

AUTOMATED VOICE: Mystery Sound.

MOLLY BLOOM: You feeling ready?

VIOLET: Mm-hmm.

MOLLY BLOOM: All right. Here it is. It's a short one, so I think we should hear it one more time. All right, Violet. What is your guess?

VIOLET: It sounds like someone like pushing buttons or maybe typing on a keyboard.

MOLLY BLOOM: Excellent. Excellent guess. Well, we will be back with another chance to guess and hear the answer a little later in the show.

VIOLET: Keep listening.

We're working on an episode about stars.

MOLLY BLOOM: And we want to hear from you. Astronomers think our Milky Way has 100 billion stars, and only some of them have names. If you discovered a star, what would you name it, and why?

VIOLET: Share your answer at brainson.org/contact.

MOLLY BLOOM: Violet, what would you name a star?

VIOLET: I would probably name it Minervdum.

MOLLY BLOOM: Oh. Tell me why.

VIOLET: Sounds cool.

MOLLY BLOOM: It does sound cool. And you know what? Sometimes, that's all a name needs to do, is sound super cool. You can send us your answer at brainson.org/contact. You can also send us questions, mystery sounds, and drawings.

VIOLET: That's how this question arrived.

ARIEL: My name is Ariel, and I live in Pittsburgh, Pennsylvania. And my question is what makes pee yellow?

MOLLY BLOOM: We'll answer that question during our Moment of Um the end of the show. And we'll read the most recent group of listeners to be added to the Brain's Honor Roll.

VIOLET: Oh, and one more thing.

MOLLY BLOOM: We wrote a book. It's called It's Alive: From Neurons and Narwhals to the Fungus Among Us. It's a fun and fact-filled journey that will introduce you to the mind blowing living things that exist on this planet. It comes out September 8, but you can pre-order it now. Just head brainson.org to learn more.

AUTOMATED VOICE: Brains on.

MENAKA WILHELM: Welcome back to Bowel Action News.

SANDEN TOTTEN: Where we flush out the truth every time.

MENAKA WILHELM: Next up, a developing story from Miles, Alexander, Julia, and Benjamin.

MILES: How does touching poop make you sick

SANDEN TOTTEN: Here's the scoop on touching poop. You shouldn't do it.

MENAKA WILHELM: Nope, you shouldn't. If someone is sick, lots of diseases can spread through their poo. Think cholera, typhoid, or just plain old diarrhea. If even a tiny amount gets inside your mouth, your nose, or your eyes, you could get super sick. So it's important to keep doodoo off your hands.

SANDEN TOTTEN: That's right. And poo can also contain parasites. So other people's poo equals dookie danger. But what about your own poo? If you're healthy, is that OK? Probably not super dangerous, but it's better to be safe and avoid caca contact.

MENAKA WILHELM: Definitely. Go ahead and treat poo like you treat a priceless work of art at the museum.

SANDEN TOTTEN: You mean put up a little card explaining what it is and charge people to see it?

MENAKA WILHELM: Well, no. I meant look but don't touch.

SANDEN TOTTEN: Ah. Yeah. That makes more sense. Words to live by.

MENAKA WILHELM: Now what about the color of caca. This is something many of you were curious about, including Violet.

VIOLET: Why is poop brown?

MENAKA WILHELM: Let's go ahead and start with the blank canvas of poos.

SANDEN TOTTEN: But wouldn't the blank canvas be white?

MENAKA WILHELM: Not in your intestines, it wouldn't be. For your basic poo, some of its color comes from a digestive juice called bile.

SANDEN TOTTEN: Ah. Bile, brown. Got it.

MENAKA WILHELM: Well, bile is usually yellowish to greenish, but bile isn't the only thing coloring your poo. Along with food and fiber and bacteria, you also poop out used up red blood cells. And those are more of an orangey brown color.

SANDEN TOTTEN: And mixing all those colors together, yellow, green, orange, that would give you brown.

MENAKA WILHELM: Poo-cisely. And depending on the exact mix, you can get different browns. So let's get to painting on that canvas, as many of you have. Charlie?

CHARLIE: I'm wondering. Why is my poop a golden-ish, yellowish color sometimes?

MENAKA WILHELM: Well, in the food category, yellow dookie could be from sweet potatoes, or carrots, or a yellow spice called turmeric. If there's more fat in your poo, it can also look more yellow. And that brings us to the next color. Mathis, you're up.

MATHIS: Why do beets turn our poop red?

SANDEN TOTTEN: There's a name for this. Beeturia.

MENAKA WILHELM: Right you are, you Sanden. Beet color comes through in your poo if your digestive system doesn't break down the chemicals that give beets their colors. Those are called betalains. Some people's bellies do break down betalains. So even when they eat beets, they poop brown.

SANDEN TOTTEN: Wow. That's like a superpower or a pooper power.

MENAKA WILHELM: This has been Bowel Action News. Your source for truthful toilet talk.

SANDEN TOTTEN: Stay gassy, everyone.

MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly.

VIOLET: And I'm Violet.

MOLLY BLOOM: Violet, are you ready to hear the mystery sound again?

VIOLET: Sure.

MOLLY BLOOM: OK. Here it is. A hint before we hear it one more time. It is very directly related to today's episode topic. What is your guess?

VIOLET: Well, now it sounds like a machine, but I don't know how that's poop-related. Maybe it's a machine calculating all the toilet flushes or something.

MOLLY BLOOM: I love that idea. It's an important job for some machine to do. Well, here is the answer.

MELISSA WILSON: That was the sound of a cow pooping and it hitting the floor of the barn.

VIOLET: That's gross.

MOLLY BLOOM: Yes. It is gross. Have you been in a barn before?

VIOLET: Yeah. I had a field trip to like a farm. It's like a public farm where you could see animals. And we were required to call all the poop milkshakes.

MOLLY BLOOM: Why?

VIOLET: I don't know. Maybe the same poop is offensive or something.

MOLLY BLOOM: So they called all the poop milkshakes?

VIOLET: Yeah. Like, hey, look. There's a big chocolate milkshake.

MOLLY BLOOM: Well, cow poops are also called manure, and farmers use manure to help nourish their crops. Here's Melissa Wilson, a soil scientist from the University of Minnesota, who shared the mystery sound with us.

MELISSA WILSON: Crops need nutrients, just like you and I do. We all have to eat, and plants do too. And one of the things that we found a long, long time ago is that if we added nutrients to the soil, we could grow better crops. And in fact, manure was one of the first things that people found that they could add to the soil.

One of the things that I really like about manure is that it's kind of a form of recycling. We use the animal waste, which has nutrients in it, to be able to fertilize the crops. Then we grow the crops, and we feed the crops to the animals. And then they poop it out again, and then the cycle goes around again.

AUTOMATED VOICE: It's a poop, poop, poop, poop party.

LOGAN: My name is Logan from Altadena, California. My question is do ants poop?

PROFESSOR CORRIE MOREAU: That is a great question. So hi. I'm Professor Corrie Moreau, and I'm an evolutionary biologist and entomologist, and I study ants. Interestingly, ants poop, but different parts of the life cycle poop in different ways. So adult ants usually poop, and it's just kind of watery, and it comes out just a little.

But when they're larva, so when they're young, they actually don't poop. They store all the poop inside their body until right before they shed their sort of exoskeleton to go into the pupal stage. So think about a caterpillar going to a cocoon. It's the same thing in ants, where you have the larva stirring up all their poop. And then right as they're transitioning to the stage in which they're going to sort of form the adult structures, they shed all the poop at once in this giant structure called a meconium.

When it's inside the body of the larva, you can actually see it because it looks like kind of a dark ball inside the body of the growing baby ant. But when they shed it, it kind of looks like a poop. It looks like long and thin, like a poop. But when they're adults, it's just usually kind of a light brown liquid. When ants emerge as adults, they actually have such narrow constrictions in their body parts, they can't eat solid food anymore. They can only eat liquid food. So that's why the poop actually looks so different.

MOLLY BLOOM: As if poop wasn't amazing enough already, it turns out this stuff is also giving us a valuable clues into the lives of dinosaurs.

VIOLET: We talked to Karen Chen about that.

MOLLY BLOOM: She studies dinosaurs at the University of Colorado Boulder.

VIOLET: Welcome, Karen.

KAREN CHEN: Well, thank you for hosting me, Violet.

VIOLET: How do you find dinosaur poop?

KAREN CHEN: Fossilized feces from dinosaurs are actually rather rare. And I have usually found them by spending time with other paleontologists who are looking for and find bones, and they sometimes come across dinosaur feces.

VIOLET: What does it look like?

KAREN CHEN: Dinosaur coprolites or dinosaur poop, fossilized feces, can be difficult to recognize because many of the ancient dinosaurs were very large, and their feces fell apart. So they didn't hold their original shape.

VIOLET: How do you tell what dinosaur made the poop?

KAREN CHEN: What I usually rely on is the contents. If it's filled with bone, I know the feces was produced by a carnivorous dinosaur. In other cases, if I just have plant material in a coprolite, again, I go to see what plant eaters are found in the same rocks as the coprolite. And then we can make our best guess. Unfortunately, with fossil feces, we just can't always tell who dung it.

VIOLET: What can you learn from studying dinosaur poop?

KAREN CHEN: Sometimes, we can learn what kinds of other animals lived with the dinosaurs. For example, we have found dung beetle burrows and snails on fossil dinosaur poop that indicated that the dung beetles and the snails were eating dinosaur poop. In other cases, I've studied dinosaur coprolites from plant eaters. Large plant eaters like duckbill dinosaurs. And their poop was filled with wood that had been rotted before it was eaten. So this was kind of unusual because most large animals, large mammals don't normally eat that.

MOLLY BLOOM: Very interesting.

VIOLET: Have you ever found something in dinosaur poop that might have been painful or difficult to digest?

KAREN CHEN: Actually, yes. The dinosaur poop that I just told you about that contains rotted wood, we also found pieces of crustacean in there. Now we don't know exactly what kind of crustacean it was, but crustaceans include animals like crabs and lobsters. And we found bits and pieces of their shells in the same poop that we found the rotted wood in. So it could have been a little sharp when it was going down.

VIOLET: Thank you.

KAREN CHEN: Well, thank you very much for being a budding scientist, Violet, and asking great questions.

AUTOMATED VOICE: Brains on.

AUTOMATED VOICE: It's a poop, poop, poop, poop party.

MALCOLM: My name is Malcolm.

KEVIN: My name is Kevin. Hello.

MALCOLM: We are from Murray, Utah. We read that butterflies do not poop.

KEVIN: Oh, pee.

MALCOLM: Do moths?

BLANCA HUERTAS: Well, butterflies and moths are closely related. They literally like cousins. They got exactly the same structures on digestive systems, and they are exactly the same insects basically called lepidoptera, which means the insects with scales on the wings. My name is Blanca Huertas. I'm the senior curator of lepidoptera. And what it means, I'm in charge of the butterfly collections at the Natural History Museum in London.

Butterflies do poop, and moths also do poop. The butterflies go from caterpillar. They eat a lot. They cover themselves. And they go into the pupa or the chrysalis. When the butterflies emerge, it's like the humans. The first thing we do when we humans is we cry, and we poop. And in the butterflies, it's exactly the same. The first, they actually poo. After that, yeah, they keep pooping.

Well, the other thing is that poo on the butterflies and in the moths is different because all of these species, they feed on different plants. And it's like us. If we eat beetroot, our poo is going to be red. On the butterflies, butterflies who eat plants with certain colorants, pigments, they're going to have different colors in the poop.

If when you are in the field and you're collecting butterflies when you need to do a study. For example, if you're collecting butterflies that feed on rotten stuff and dead animals and stuff because all of them feed on pretty flowers. That's true about butterflies, I'm afraid. So actually, you get to see that poop into the nets that we use for collecting the butterflies.

MOLLY BLOOM: Another thing scientists are looking at is how poos help with certain kinds of infections.

VIOLET: There's a procedure called a fecal transplant. A poo transplant.

MOLLY BLOOM: And doctors have used these transplants to help people who have a kind of infection in their intestines called Clostridioides difficile or C. diff for short.

VIOLET: Our favorite fictional poo-tuber made a video about that. Let's check it out.

TAYLOR: Hello, cuties. Hi. Welcome back to your favorite poo-tube channel with yours truly, Taylor the Turd. As a poo, you might think the gut is, well, behind you. Most of us would never think to go back into the gut once we leave. But today, I want to encourage everyone, to ask not what a gut can do for you, but what you can do for a gut.

Because some guts have problems that dookies like us can solve, in a procedure called a fecal transplant. Speaking of qualifications, I usually keep this to myself, but I'm actually an MD PhD. That's medical doodoo, pretty hot dookie. And I had a fellow named on for this special vid.

DR. MARIBETH NICHOLSON: Hi. I'm Maribeth Nicholson MD, and that's a doctor of medicine.

TAYLOR: So Maribeth, let's hear how you're using the fecal transplant first.

DR. MARIBETH NICHOLSON: The reason I've been using it is for the treatment of C. difficile infection. And C. diff is a bacterial infection that can cause a lot of abdominal pain and diarrhea and commonly follows antibiotics.

TAYLOR: C. diff sounds terrible. But poos, listen up. Here's where you and I might make a giant difference in someone's life. By moving into a new person's gut, we could help someone rejuvenate their microbiome. That's the community of microbes that live in someone's got.

DR. MARIBETH NICHOLSON: So we think about our colon and the microbiome in our colon similar to how we think about a garden. So if our garden is really full of shrubbery, and trees, and the plants that we want to be there, there's really no place for those weeds to become established.

TAYLOR: And in this case, bad bacteria like C. diff are the weeds. But if you are a poo that was made in a healthy gut, you are chockfull of healthy microbes. The lovely shrubs and trees of a gut garden. So you could go into another gut and make some major landscaping improvements. It's like a garden transplant for the bowels. Now not everyone can be a fecal transplant, but the who's who can should really consider it.

DR. MARIBETH NICHOLSON: Yeah. I think if a poo has really been careful and working out and is in their top poo shape, that this would be the perfect career for them.

TAYLOR: Here's what to expect. First, you'll have to prove that you don't have any diseases or parasites. So doctors are going to give you a lot of tests. They're going to test the human you came from too. Good luck. If you pass, it's time for your transplant procedure.

DR. MARIBETH NICHOLSON: And then we're going to add you to a bottle of water, and we're going to mix you up really, really good.

TAYLOR: Listen. I getting liquefied sounds scary, but most poos are like 3/4 water anyway. So it might not feel as strange as you'd think. You won't get transplanted as a solid. Liquid only. But you'll still have plenty of microbes to bring to your new home and someone else's booty.

DR. MARIBETH NICHOLSON: When it's time for you to go to your new home, you're going to get squeezed through a really tiny syringe into this really tiny channel.

TAYLOR: That channel is a plastic tube. It's like a plastic portal to take you from out in the world to your new home. Congratulations. You've made it to your new colon.

DR. MARIBETH NICHOLSON: Your job now is to cling on to that colon and make it all better and reestablish that healthy microbiome.

TAYLOR: So take off your shoes, if you're a poo who wears shoes, and relax. Let your microbes settle in. With your help, your new home will be making healthier poos in no time. OK. That's it for today's video. I hope you feel more informed about fecal transplants and why you as a poo might one day want to go back to a gut, for the good of the gut. That's all for today. If you like this video, go ahead, give me like. And click the bell. That way, you'll get poo-tifications and never miss one of my videos. Bye, everybody. See you soon.

AUTOMATED VOICE: It's a poop, poop, poop, poop party.

AVI: Hi. My name is Avi from Baltimore, Maryland. And my question is why does geese poop look different from normal bird poop?

NICOLE JACKSON: Hi. My name is Nicole Jackson, and I'm an environmental educator and bird watcher. I live in Columbus, Ohio, and I currently work at the Ohio State University as a program coordinator. I love birds. I love watching birds, and I love going on hikes to see birds. So first, we want to mention that birds are using their habitat in different ways.

So for geese, they're waterfowl. And a lot of people will see them eating aquatic plants, and that ties into the color of poop. So when we think of urine and feces, how humans do those things versus how birds do those things, it's very different. The cloaca is used to lay eggs. They use that to urinate, to poop. The birds take the nitrogen that they absorb and turn that into uric acid. That's where the color comes in.

So the uric acid makes the poop white. And then because the geese are eating these green plants on a regular basis, it's all going to the same place. So it all just mixes together, and you have a combination of green and white. Sometimes, it's all green. Sometimes, it may be brown. Because of that diet, those colors are going to show up versus typical birds that we see, which is a lot of white kind of mixed with black or gray because they're not eating as much of the green plants. It's more of seeds, bugs, things like that.

VIOLET: Food goes through a lot before becoming poop.

MOLLY BLOOM: Bacteria in your gut help break food down, and the gas they release makes farts and poop smelly.

VIOLET: The color of poop comes from digestive juices and old red blood cells, plus the stuff you eat.

MOLLY BLOOM: And poop has nutrients in it too. So farmers can use that in the form of manure to help their crops grow.

VIOLET: Scientists are studying fossilized poos to learn about dinosaurs.

MOLLY BLOOM: And researchers have also used poo transplants to treat certain infections. That's it for this episode of Brains On.

VIOLET: It was produced by Sanden Totten, Molly Bloom, Meneka Wilhelm, and Marc Sanchez.

MOLLY BLOOM: We had production help from Christina Lopez, engineering help from Johnny Vince Evans, and special thanks to Mickey Bloom, and Bogan, and Rosie DuPont.

VIOLET: Brains On is a non-profit public radio program.

MOLLY BLOOM: You can support the show by visiting brainson.org/fans.

VIOLET: Now before we go, it's time for a moment of Um.

ARIEL: What makes pee yellow?

PATRICIA YOUNG: Pee is yellow because of a chemical compound called urobilin. This compound is yellow. Hi. I'm Patricia Young. I study fluid inside animal's body, such as peeing, pooing, and blood. We make pee by our kidney. Kidneys are located right below your belly, and they have two, left and right. Kidneys help filter and process our body waste in liquid form. So they recycle water and filter out the waste and transport the waste from kidney to bladder.

Urobilin is a chemical created by the kidney. The urine is the mixture of this chemical and water. I have studied animal peeing and pooing, pretty much which one pee faster than the other. I found that for animals bigger than 3 kilograms, including human, they all pee about the same time. So in other words, humans and elephants all pee from 10 to 30 seconds.

There is some animals that pee way faster than what I said. It's for animal that's smaller than 3 kilograms. Like say mice, rats, and bats. These animals, they could pee like less than 1 second, and their pee, you can only see it through high speed camera, and they pee like droplets, instead of a jet.

MOLLY BLOOM: These names are number one in my heart. It's time for the Brain's Honor Roll. These are the amazing listeners who send us their questions, ideas, mystery sounds, drawings, and high fives. [LISTING HONOR ROLL]