Everything You Ever Wanted to Know About Poop

[Music] whooping everybody does it which maybe makes it seem like kind of a mundane thing but we've actually made a lot of poop related episodes on scishow because there's a ton of interesting science behind it there's the feces itself how our bodies process it the technology we use to handle it and also some ways we encounter or seek out other animals poop so here's a collection of just some of our episodes about poop and if you're currently sitting around with your family for the holidays maybe just unplug your headphones and turn up the volume so that everyone can experience the glorious science of poop you really wouldn't want them to miss out would you it turns out that one of the most commonly googled questions in the world is why is my poop green so up first 2014 Hank is gonna tell us why that happens you can ask the internet anything you want like how big is the universe or what's the average lifespan of an Olive Ridley sea turtle or why are sloths so lazy but many of you turn to the wisdom of the Internet to explain what you find in the toilet bowl according to our friends at Google one of the most commonly googled questions in the world at least in English is why is my poop green and hey fair enough we're all about fostering curiosity here and what's more fascinating than the human body so in order to answer this question we should start out really with why is poop normally brown the brown color of most mammalian feces comes from a substance called bilirubin which is produced by your liver when it processes dead used-up red blood cells and then prepares them to be excreted the bilirubin is actually made from hemoglobin the protein that your blood cells use to ferry oxygen around your body but even though your red blood cells are red the bilirubin itself is yellow and it's absorbed by your liver and excreted as bile which is yellowish green because of all the bilirubin in its the liver secretes bile into your small intestine where its main job is to digest fats breaking down lipid molecules into fatty acids but since the bile is on its way down your body anyway it's also chock full of waste material including that bilirubin so the fact is because of all the bile in it your feces actually start out a yellowish green color typically as this junk travels through your digestive system the bilirubin is broken down by your gut bacteria those wonderful microbial minions that live inside your intestines and help you absorb nutrients while decomposing waste these bacteria eat the bilirubin and metabolize it into a byproduct that's colorless but when that byproduct reacts with oxygen it turns brown forming a pigment called starck Oh bile in stereo violin is what makes your poop brown so if your poop is green it means that it went through your digestive system too fast and the bacteria didn't have time to digest your bilirubin into its by-product so if you notice this stuff's a little greener after you take a laxative or have a touch of food poisoning or maybe super hungover something else might be going on that's hurrying your poop along too quickly so the occasional green turd is probably nothing to worry about but if it's all that color it could mean that your feces aren't spending enough time inside of you for your intestines to absorb all the nutrients you need mystery solved well that's one question answered but I have so many other questions about poop like when I go to the local wing joint for wing Wednesdays and I eat a bunch of super spicy wings I know that I might be signing up to re-experience that spiciness about 12 hours later well why does that happen it doesn't make any sense well Olivia has the answer lots of people love the painful deliciousness of spicy food at least when it's in your mouth but why do foods that burn going in also burn going out well turns out it's for the same biological reasons because in some ways your butt is a lot like your mouth lots of spicy foods get their pungency from a chemical called capsaicin it's produced by plants in the genus capsicum which includes Chili Peppers and their relatives capsaicin binds to a receptor expressed all over your nervous system called trip v1 it has a handful of jobs but it's best known for its role in pain when there are risky levels of heat this receptor tells your danger sensing cells and other chemical messengers to send signals to your brain which can make you feel pain and because trip v1 also interacts with capsaicin molecules you feel the burn of habaneros in your mouth according to your nervous system hot peppers actually feel hot temperature-wise but trip v1 receptors are in lots of places and that includes your anus see the capsaicin you eat doesn't get completely digested some of it does get absorbed by your body and sent to your liver to be broken down but some of it sticks around and gets pooped out which means the trip v1 receptors in your anus can interact with capsaicin just like the ones in your mouth ouch there are actually trip v1 receptors all along your digestive tract which is why some people get cramps or discomfort from spicy foods and when your body's being told that things are way too hot it usually tries to cool down you sweat your nose runs and your mouth waters in an attempt to cool off and flush the offending substance your intestines might get in on the action and throw in some water too and that's why your spicy food poop is sometimes looser than normal now consuming capsaicin regularly can actually make your body desensitized possibly by decreasing the amount of certain chemical messengers so your brain reports less pain like oh okay this happens all the time there's no fire or real danger everything's fine in fact using low doses of capsaicin for pain relief is an active area of research so go ahead and order those jalapenos on your pizza because maybe eating spicy foods more regularly will help with those burning bowel movements even though it might not be super Pleasant in the meantime hmmm finding out that my mouth is in any way like my butt makes me regret asking just a little so now I'm a little afraid to ask but why does poop sometimes float have you ever looked down after doing your business and noticed that your poop is floating maybe this comes and goes or maybe your poop is always buoyant you might have even worried that this was a problem like if you look it up online a lot of reputable websites will mention that one reason your poop floats is because of fat that is less dense than water and so the thinking goes if you have enough of it in your poop that's probably why it floats but fatty stools what doctors like to call steatorrhea stools happen because you aren't absorbing the fat that you eat and that's usually a sign of a really serious problem like pancreatic cancer or cystic fibrosis back in the early 70s Michael Leavitt and William Dewayne a pair of researchers at the University of Minnesota were annoyed by this assumption that fat is why feces float they suspected that trapped gas was the more likely culprit after all about 15% of perfectly healthy people including Dwane consistently had bobbers so they decided to investigate and kindly wrote up their results in the prestigious New England Journal of Medicine in a paper called floating stools flatus versus fat 33 healthy volunteers some with floaters donated samples along with six patients with steatorrhea the scientists put the specimens in flasks with water to see if they sank if not they added pressure to squeeze out any gas and check to see if anything still floated but even the fattiest poops sank to the bottom Wendy gasped in fact the scientists determined that it's almost impossible for a bowel movement to float just because of its fat content you would need it to be half fat so gas creates most of the uplift but what is it and where is it coming from luckily our gutsy duo also analyzed the poo samples with gas chromatography to separate out the compounds and identify the mysterious gas it turns out that a big part is methane the same stuff in natural gas it's made by special bacteria in the colon called methanogens everybody has some of these bugs but some people seem to have way more like William duane who admitted in his paper that he produced methane at your record proportions methanogens run on hydrogen and can ferment fiber in the gut a bit like a cow can that means you get more energy out of fiber rich food like beans so don't believe everything you read online about your poop if you have floaters you could just be gassy and if you have fatty poop that happens to float well that's because of gas too ah I guess it does make sense that gas would be involved in one of these answers in the history of humanity we've certainly come a long way since we were just pooping out in the woods somewhere and it took us a long time to arrive at the modern sewage treatment systems we have today it also took an event that is now known as the big stink so here's a longer episode that explains where the poop goes after you flush and how we treat it to keep ourselves safe the year is 1858 the city is London an oppressive heat wave is scorching the cities two and a half million residents in the Thames River where for centuries Londoners have disposed of their waste begins to stink bad like really bad water levels drop as raw sewage bakes in the Sun casting a fetid smell so powerful that it's set to strike men down it would go down in history as the big stink all three of those words capitalized and as unpleasant as it was it's remembered today as a tipping point of sorts that eventually ushered in the age of modern sewage treatment humans have always peed and pooped of course but where it goes after we've done our business has changed a lot especially in the last hundred and sixty years as a result of the great stink London ended up building more than 20,000 kilometres of underground sewers to channel human waste downstream where it could be released but still untreated and it turns out that just diluting and dispersing sewage and hoping for the best isn't great public health policy I mean the Greeks and Romans were doing the same thing 2,000 years earlier not exactly progress over time it became clear that human waste not only had to be disposed of but it also had to be rid of the pollutants that are harmful to humans in the environment what is it that makes pooping pee so dangerous in the first place I mean this stuff comes from your body so it doesn't make you sick while it's in there why is there a problem well we're learning a lot of these days about the human microbiome the wonderful habitats that your body provides for literally trillions of microorganisms and it includes your waste making parts like there's growing evidence that your urine isn't actually sterile though for a long time we thought it was and your intestines are populated with huge bacterial colonies that you actually need in there to help digest your food and fend off some infections unfortunately we're not all healthy a hundred percent of the time and the viruses and bacteria that make us sick are found in our poop so human waste can contain all kinds of pathogens like Salmonella and e-coli and the microorganisms that cause cholera typhoid and hepatitis and you got parasites like hook worms and protozoa and Giardia which campers may be familiar with after drinking improperly filtered water and it's more than just a problem for humans wastewater also contains lots of nitrogen and phosphates that can harm wildlife and water quality if released into the environment so while a lot of us take it for granted to dealing with these challenges is harder than you might think lack of access to clean water and flushing toilets is a serious public health problem in many developing countries the treatment processes that so many of us use aren't available to well over a billion people the wastewater journey usually takes one of two directions at either heads by way of a pipe to your towns local sewer or into a septic tank right there by your own home even though many of us live in big cities backyard septic systems are actually very common as many as 25% of people in North America depend on them to process their waste and distribute it into the ground scientists learned long ago that the anaerobic digestion of sewage by microorganisms could be extremely effective in breaking down human waste and eliminating pathogens the word septic actually comes from the Latin word for the bacterial action that you know as rotting all the stuff that goes down your toilet which wastewater management types call black water and all the stuff that goes down the drain and your sink in your shower or gray water flows into that tank which usually holds about 4000 litres of liquid then in the span of about two days naturally-occurring anaerobic bacteria get to work reducing solids in the wastewater into liquids and a kind of greasy fatty residue the insoluble particles will sink to the bottom and form a sludge while the fats form a layer at the top of the tank and yes I realized that I am probably ruining your day at this point but within 48 hours the bacteria will break down the wastewater in a septic tank by about 40 percent and they stay in the water when it flows out of the tank into an underground drainage field here the bacteria continued to do their thing while the soil acts as a biological filter of sorts keeping any harmful organic material from reaching the groundwater supply the soil contains oxygen which allows aerobic bacteria to enter the mix and it also takes some of the phosphorus and forms of nitrogen like ammonia which plant life really enjoys so yeah if you're off the sewer grid all that's going on in your backyard right at this very moment kind of makes you not want to walk around in your bare feet anymore doesn't it but for those of you connected to a sewer system what kind of magical journey awaits your waste and because I know some of you are curious what happens to the stuff that you flushed down your toilet that isn't your own expertise well before it flows into your local treatment plant wastewater goes through a screen of met rhod that catches all the big stuff sticks and clothing in small animals and other weird non pooed at find its way into the sewers so that none of that gets into the moving parts of the facility from there it's on to the settling tank aka the grit chamber which is where solids like sand and gravel that have been picked up along the way settle to the bottom it's also at one of these two early treatment stations where other flushable czar removed and there are literally tons of this stuff according to one estimate as much as 50% of the so called non dispersible material and wastewater is paper towels from public restrooms another 25% is nothing but baby wipes and the remaining 25% is a mixture of condoms and cosmetic wipes and tampons and random things that toddlers probably got their hands on the process for removing them varies depending on the system but usually involves another mechanical screen or skimmer the real treatment begins at the next stage called the primary clarifier this circular Basin slows down the sewage so that the heavier organic solids fall to the bottom the solids at the bottom will be removed and transferred to a digester sludge press or drying bed which we'll get to I promise so back to the primary clarifier most facilities also use a skimmer here to remove fats and oils and grease that float to the top these substances most of which come from cooking materials or Road runoff will also be diverted into the digester the largest change in the science of wastewater treatment over the last few decades is that the process used to stop right here people are like hey okay we got the sludge out the water is good to go back in the rivers except it's not as we discussed earlier the wastewater is still full of potentially dangerous pathogens which is why we now have what's called secondary treatment wastewater from the clarifier flows into an aeration basin where air is added to foster an efficient environment for microorganisms that unlike those used in most septic systems consume both organic matter and oxygen at this point the water is known as activated sludge and it looks like dark mud it's rich with active bacteria and protozoans that go to town on the oxygen-rich water from there the water heads to a secondary clarifier and yet another sedimentation basin it's one last time for any leftover heavy stuff to fall to the bottom where it's pumped to the digester and while the name is kind of gross in this context the digester does pretty much what it sounds like it eats your poop inside it has an anaerobic environment similar to a septic tank where bacteria can break down sludge reducing the volume the odors and most importantly disease-causing organisms some facilities use drying beds for this step but either way the material left over from this process is called bio solids or treated sewage sludge it wasn't so long ago that we took these bio solids and tossed them into a landfill once they were through treatment but today this leftover dry sludge is often used as fertilizer for agriculture or use to make compost mixtures that are sold commercially so again yes you may have used the very diluted byproduct of human poop to grow the veggies in your garden we here at scishow love recycling after all those solids are taken care of we still have a bunch of waste water left over now that needs to be disinfected before being released into the wild also known as our drinking supply there are lots of ways to do this some facilities use chlorine to kill any harmful bacteria still left in the water chlorine can be introduced as a gas or a salt either way it reacts with the water to form hypochlorous acid which ultimately breaks down bacterias cell membranes and kills them imploringly is really effective but if you live in a town that uses it you know that it does not taste good at all chlorine also can be dangerous for organisms in the rivers and streams that receive the wastewater which is why some places now dechlorinate water after chlorinating it this is done using sulfur dioxide gas which quickly turns chlorine compounds into chloride ions which makes the water less toxic a more expensive but less chlorine II method involves using ultraviolet light which effectively sterilizes microorganisms changing their genetic composition enough that they can no longer reproduce some newer wastewater treatment plants now even go an extra step with what's called tertiary treatment it can be a physical process where water is run through sand filters to reduce any remaining solids or it can be done biologically some places divert the water to natural wetlands where plants remove excess nutrients but this is the end of the line no matter what the disinfectant process the effluent will be released usually into a nearby river or Creek ready for you to possibly drink again someday European poop has come full circle so refreshing so it turns out that the history of poop is rich with stories apparently in the mid nineteenth century there was a worldwide craze for the poop of a particular species of bird throughout history humans have prized a lot of animals for making products that we find beautiful or useful silkworms for their silk whales for their blubber sheep for their wool but in the mid-1800s a bird called the Guan a cormorant was considered the most valuable in the world it was nicknamed the billion dollar bird because it's poop or guano was an amazing fertilizer at the beginning of the 19th century populations were exploding and all of those people needed to eat large-scale agriculture had been booming for a few hundred years and soils were quickly getting depleted of nutrients enter Alexander von Humboldt European explorer extraordinaire while exploring the coast of Peru in 1802 von Humboldt came across workers unloading a shipment of guano from the Chincha islands indigenous cultures in the area had been using the guano on these islands as a source of fertilizer for hundreds of years so von Humboldt definitely did not discover guano like any good Explorer he took a sample of it back with him to Europe and at the time people didn't know much about the science of fertilizers farmers recognized that adding things like ground-up bones ash or feces to soil helped plants grow but scientists weren't sure why this worked we now know the answer is elementary actually elementary like literally it's elements that are involved these materials have a lot of nitrogen phosphorus and other elements that help plants grow Lance used nitrogen to make important proteins and pigments like chlorophyll which let them absorb sunlight and do photosynthesis and not die phosphorus is needed to make DNA and RNA as well as cell membranes and the molecules that all living things use to make and store energy without these elements plants can't make more cells or even function with the cells they have but even if scientists had known this at the time it wouldn't have helped them very much there just weren't many good sources of nitrogen and phosphorus that plants could use there's plenty of nitrogen in the air of course but plants can't just suck it in like carbon dioxide I usually rely on bacteria in the soil to convert or fix the nitrogen into a different form like nitrate or ammonium that they can actually use if the soil has been exhausted of these chemicals it's really hard to grow crops which brings us back to the Chincha islands turns out bird guano is amazingly rich in these sources of fixed nitrogen and phosphorus in fact it's even better than cow dung or horse dung cows and horses only eat plants but guano cormorants feast almost entirely on anchovy like fish that protein-rich diet means lots of nitrogen eventually shows up in their poop plus bird poop is really poop and pee combined so that's extra nitrogen and phosphorus that other animal dung leaves out as for why this natural fertilizer could just pile up thank the dry climate of coastal Peru and most of the world bird poop will simply get washed away but ocean currents from Antarctica ensure it almost never rains on the islands allowing guano to harden locking in layer upon layer upon layer of nitrate phosphate goodness so when word finally reached Europe that von Humboldt had potentially found a great new source of fertilizer they went crazy for it almost immediately the Peruvian government started huge mining operations selling the guano to any country that wanted it other countries got involved too in 1856 the United States even went so far as to pass the guano Islands act which allowed American citizens to claim any Island they wished as long as it had guano on it and wasn't already claimed by another country water winners came from all over the world harvesting the seemingly limitless resource but while the guano boom was great for agriculture it was bad news for the iguana cormorant and other seabirds that called the islands home miners ate the birds and their eggs which was not really smart when you think about it and destroyed their habitat to the point that their populations began to fall by the 1870s most of the guano on these islands had already been mined a few decades later Peru started protecting the remaining cormorants it's one of the first examples of the government stepping in to protect a natural resource but for the guano industry it was too late with fewer droppings to mine and the discovery of artificial fertilizer the guano boom went bust German chemist fritz haber had figured out how to fix nitrogen from the air and turn it into ammonia which could in turn be used to develop synthetic fertilizers these worked just as well if not better than guano and now we've been using these fertilizers for decades to feed billions of people but Watto might not have outlived its usefulness just yet recently the rise of organic farming has increased demand for high-quality organic fertilizer and guano is one of the best now after all this talk about poop you might feel the need to go out and get some fresh non smelly air like maybe by going to the beach and doing some sunbathing at least if you're in the southern hemisphere because it's winter up here but I am sorry to tell you you can't escape poop up next Michael is going to tell you all about how those lovely white sandy beaches are nothing but a bunch of ground-up fish poop let's say you wanted to make yourself a white sandy beach you know like the ones in Hawaii or the islands in the South Pacific where people take luxurious vacations and lots of Instagram photos it turns out the recipe for that picturesque white sand is pretty simple there are a couple steps involved but just one main ingredient poop the first thing you'll need is a coral reef it's location specific and unfortunately there's no store-bought alternative coral reefs are made up of thousands of tiny polyps which are squishy sacs with tentacles that can sting and catch prey kind of like seein enemies these polyps are anchored to a sturdy skeleton that they make by laying down a crystallized form of calcium carbonate called aragonite which is a bright white color reefs are found in parts of the ocean that are considered to be oligotrophic which means that there aren't that many tasty nutrients floating around like phosphate or nitrate and coral polyps aren't exactly mobile so if they were left to their own devices they might starve but coral polyps aren't alone they get help from an algae called zooxanthellae that lives symbiotically in their tissues these algae can photosynthesize changing sunlight carbon dioxide and water into food energy and share a large chunk of that energy with the coral as coral polyps get more energy they build out their skeletons and grow the reef and these algae are also what give coral it's bright colors when you have a thriving coral reef other undersea plants and animals move in and begin to form a whole ecosystem and to get your white sandy beach you need some parrotfish or more specifically their poop parrotfish get their name for their bright colors and their weird bird like beaks these beaks are actually made of fused teeth called dental plates which help them graze for their main food source algae parrotfish spend their days scraping away coral reefs eating polyps for the zooxanthellae inside and any other algae they can find they're not super careful or picky so they end up swallowing mouthfuls of calcium carbonate to which they can't digest for nutrients or energy but the parrotfish have a secret weapon their throats are hiding another set of teeth called pharyngeal jaws that can grind up the coral skeletons like the xenomorph from alien but in real life this makes it easier for the chunks to travel through their digestive system and they get rid of this calcium carbonate in streams of the purest whitest tropical sand in fact according to some studies one parrotfish can poop out around 300 kilograms of sand or more in a single year after some ocean currents stir everything around you have yourself a pristine white-sand beach perfect for strolling sunbathing and building sandcastles as long as you don't mind fish poop well hopefully we haven't ruined everything for you thanks for joining us here on scishow to review our catalogue of videos about poo honestly we couldn't even include all of them in one video so we'll probably have to do a poop compilation number two at some point so if you don't want to miss that or any of our other videos go ahead and hit that subscribe button and I hope you enjoy the rest of your holiday season now that you're armed with all these poop facts that you can go share with your family and friends [Music]

Channel: SciShow

Views: 310,482

Rating: 4.8780489 out of 5

Keywords: SciShow, science, Hank, Green, education, learn, poop, stefan chin, turd, toilet, compilation, special, spice

Id: h4g2xAlsj-4

Length: 25min 57sec (1557 seconds)

Published: Tue Dec 25 2018