What is poop made of?
About 3/4 of your average turd is made of water. Of course, this value is highly variable - the water content of diarrhea is much higher, and the amount of water in poop that has been retained (voluntarily or otherwise) is lower. Water is absorbed out of fecal material as it passes through the intestine, so the longer a turd resides inside before emerging, the drier it will be. Of the remaining portion of the turd, about 1/3 is composed of dead bacteria. These microcorpses come from the intestinal garden of microorganisms that assist us in the digestion of our food. Another 1/3 of the turd mass is made of stuff that we find indigestible, like cellulose, for instance. This indigestible material is called "fiber," and is useful in getting the turd to move along through the intestine, perhaps because it provides traction. The remaining portion of the turd is a mixture of fats such as cholesterol, inorganic salts like phosphates, live bacteria, dead cells and mucus from the lining of the intestine, and protein.

Why does poop stink?
Poop stinks as a result of the products of bacterial action. Bacteria produce smelly, sulfur-rich organic compounds such as indole, skatole, and mercaptans, and the inorganic gas hydrogen sulfide. These are the same compounds that give farts their odor.

Why is poop brown?
The color comes mainly from bilirubin, a pigment that arises from the breakdown of red blood cells in the liver and bone marrow. The actual metabolic pathway of bilirubin and its byproducts in the body is very complicated, so we will simply say that a lot of it ends up in the intestine, where it is further modified by bacterial action. But the color itself comes from iron. Iron in hemoglobin in red blood cells gives blood its red color, and iron in the waste product bilirubi gives rise to its brown color.

What other colors of poop are possible?
Poop is mostly shades of brown or yellow, but other colors can arise under certain circumstances. For example, someone with a bleeding ulcer might have tarry black poop from the presence of partially indigested blood. Bleeding in the intestine, from an anal fissure or split, for example, can stain the poop red. Some illnesses in babies give them green or even blue-green poop. But another source of blue poop in children is more innocent: it can come from eating a concentrated source of blue food coloring such as ice cream. Intense red food coloring can produce bright red poop. Sometimes brightly colored foods pass through the gut almost unchanged, and the turd may be speckled with bright red fragments such as pimentos, or bright yellow kernels of corn. One can experience white poop after consuming a barium milkshake for the purposes of getting an x-ray of the upper gastrointestinal tract.

Why do dogs eat poop?
Many animals eat poop on a regular basis. These include rabbits, rodents, gorillas, many insects such as dung beetles and flies, and yes, dogs. (Keep that in mind the next time a dog wants to lick you!) Herbivores such as rabbits and rodents eat their own poop because their diet of plants is hard to digest efficiently, and they have to make two passes at it to get everything out of the meal. This is equivalent to a cow chewing its cud; only cows are able to re-eat their food without having to poop it out first. Another reason why animals eat poop is that poop contains vitamins produced by their intestinal bacteria. The animal is unable to absorb the vitamins through the intestinal wall, but can get at them by eating the poop. Another reason that animals such as dogs eat poop is that poop contains a certain amount of protein. Dogs are particularly fond of cat poop because cat poop is high in protein. I had a friend with a dog and a cat, and he never had to clean the kitty litter. The dog took care of it.

Are there people who eat poop?
Yes, we all have, at one point or another. One of the main ways that diseases and parasites spread is through the consumption of food and water contaminated with feces. This happens because people don't wash their hands carefully after pooping or changing a diaper or scratching their butt. It can also happen through careless disposal of diapers. Our microbiologist here on Guam says that one dirty diaper in Tumon Bay can send the bacteria count through the ceiling. But of course, what you want to know is, are there people who eat oop on purpose? Again, the answer is yes. Some autistic children practice coprophagy, the ingestion of feces. Coprophagy is also listed as an unusual sexual practice in the encyclopedia of that name. I have known only one person who ate poop on purpose, and she only did it once, when she was about four years old. She says she was curious about what it tasted like. When asked what poop does taste like, she replies, "About like you'd expect." By the way, for all of you who are wondering, the author of this page does NOT eat poop.

Can you get sick from eating poop?
Yes, you can definitely get sick from eating poop, even in minute quantities! Although urine emerges sterile from the body (unless the person has an infection), poop emerges loaded with bacteria and sometimes other life forms. Many diseases, including food poisoning, cholera and typhus, are spread by fecal contamination. Many parasites, such as the notorious tapeworm, can be spread through deliberate or accidental ingestion of poop. There are some parasites, such as pinworms, which depend on people eating their own poop to keep the population up. Pinworms are small nematodes that live in the colon. The females emerge from the anus at night to lay their eggs. Their activity makes the anal area itch. The person scratches the itch (often doing so in his sleep), procuring a small amount of fecal matter and eggs under his fingernails, and then puts his fingers in his mouth. Once the eggs are consumed, the person is infected with a new generation of pinworms. I have read that almost everyone has pinworms. Luckily, pinworms don't do much harm. You only notice them if you have a lot of pinworms! If you want to find out if you do indeed have them, get someone to gently touch around your anal area with Scotch tape while you are sleeping. The worms will stick to the tape and you'll be able to see them.

Do most people wipe their leftover poop standing up or while sitting on the pot, and are there gender differences?
This isn't really scientific, but I did a quick survey, and everyone asked (including both males and females) said that they wipe sitting down. There was even a reason provided: that sitting down spreads the cheeks apart and makes access easier. This survey was done on Guam, and Guam is technically part of the United States, and most people here probably use American toilet habits. However, if you travel a bit, you will discover that people deal with leftover poop in different ways in other parts of the world. In Europe, for example, that water fountain in the bathroom isn't for drinking. It's a bidet for hosing off after using the toilet. In Southeast Asia, you don't sit on the toilet at all. The toilet is a low, porcelain-lined trench, and the user squats over it. Next to the toilet is a bin of water. You scoop water out of the bin with your left hand and use that to cleanse yourself. You aren't supposed to use your left hand for any other purpose.

How come when you eat corn, no matter how much you chew it, you poop it out in whole kernels?
Corn poop is one of the greatest mysteries in life. I grew up pondering the same question. This is what I think is happening: When we chew corn, the outer coating slips off the inner kernel. This outer yellow coating is almost entirely cellulose, and is indigestible. It passes through the gut untouched, and emerges looking like a whole kernel, although it is mostly just the outer skin. The inside of the kernel is starchy and ingestible, and that is the part that we succeed in chewing up.

Is there any way to prevent corn from getting in your poop?
I know of only one way - don't eat corn!

How does poop stay together, like in links?
In humans, soft poop is really one long, mostly continuous sausage before it comes out. It gets its "link" look because we tend to pinch off lengths of it with the anal sphincter as the poop emerges. If a person pinches hard enough, the poop separates into several turd units. If the person doesn't pinch that hard, the turds may stay connected. If you can remain sufficiently relaxed, you can produce an awesomely long poop that will coil up inside the toilet.

Why does some poop float?
Floaters are turds that have an unusually high gas content. Sometimes the gases produced by bacteria in our gut don't have a chance to collect into a large fart bubble, but remain dispersed in the feces. The poop then comes out foamy, and has a lower density than water.

What causes the burning sensation sometimes associated with poop?
This is generally caused by a recent meal of hot peppers or related spices. The oils associated with these foods remain intact and active all the way through one's gastrointestinal system. These oils can also generate hot farts.

Why does some poop hurt when it comes out?
Turds can get very large and dry if a person is constipated, causing painful stretching of the anal opening. Pooping can also hurt if the person has hemorrhoids. Hemorrhoids are engorged veins in the anal area. A doctor once described them to me as "varicose veins of the anus," which suggests that the valves in the veins that are supposed to keep the blood flowing in the right direction have gotten messed up. Pooping can also be painful if the person suffers from an anal fissure, a tear in the tissue of the rectum.