Eat, chew, swallow. Whatever you have ingested is on its way to your stomach, where it will mix with acids and enzymes. The resulting substance – a thick juice – will then head for the small intestine, where 95 percent of the food’s nutrients will be absorbed and bilirubin from red blood cells will color it brown. Shunted into the large intestine, it will be processed by the 500 kinds of bacteria that live there. This is no cause for alarm: only 10 percent of our cells are human, while the rest are microbial. The next stop is the colon, which will send nervous signals to the brain indicating you need to go to the toilet. Find one, before peristaltic waves start pushing the waste down to your anal passage. Holding your breath at this stage can exert helpful pressure on your intestine. Finally, use your anal sphincters to push the waste out.
Flight AH245. Seat 36B. The airplane: a Boeing 747. Four hundred and eighty passengers, eight bathrooms and eight hours to go. You cross yourself, praying that your stomach won’t move too much.
There’s a bitter taste on your tongue. Your liver, sluggish from stress, is overproducing bile, and vapors are finding their way through your intestines and up to your mouth. Blame Lomotil, the anti-diarrhea medicine the smuggler gave you. For weeks now, you have been eating only soup. All that liquid has trained your guts to move slowly, but also to absorb too much water. Combined with the Lomotil, that means a lot of constipation. Never mind: you have that in common with at least 80 other passengers, as 17 percent of the world’s population have the same affliction. Yours, however, was self-inflicted when you swallowed the 50 latex-wrapped packets of cocaine now in your stomach.
Latex can degrade in the stomach. Acute cocaine intoxication would then follow.
Here comes the food. Decline it. Anything in the meal could restart your digestive system and explode one of the capsules. They are already a risk, as latex can degrade in the stomach. Acute cocaine intoxication would then follow: your heart would beat erratically, your blood pressure would soar, and you would have a seizure. You might have a stroke, a brain hemorrhage, a heart attack, or your spasming muscles and tightened blood vessels might overheat and “boil” you to death. You would then be added to the 56 percent of drug mules – also known as swallowers or stuffers – who die when their cargo leaks.
Ingest pure excrement if you like, but beware of passengers. A gram of human feces can be a comfortable mobile home for 10 million viruses, 1 million bacteria, 1,000 parasite cysts and 100 worm eggs.
Worms thrive in shit. A billion people are infected by Ascaris worm, the most common and hardiest non-microbial human parasite (it can live 10 years in a speck of excrement). Another billion have hookworm, which lurks in feces and burrows through bare feet. Along with giant tapeworms, whipworm and pinworms, they all make up the world’s heavy “worm burden.” Worms can kill, stunt childhood development and cause malnutrition. But humans and parasites have a complicated relationship: When hookworm and Ascaris were eradicated in parts of Ethiopia, asthma rates soared. Parasites seem to stimulate our immune system in ways still not properly understood.
This corkscrew-shaped bacterium loves to live in small fecal particles in water. It causes most of the world’s cases of gastroenteritis, and is common in swimmers who swallow water.
Salmonella isn’t just about eggs. A subspecies, Salmonella typhi, usually swallowed in shit-contaminated food, causes typhoid fever, which infects 16 million people a year.
It takes only 100 Shigella bacteria to cause severe dysentery. As with all fecally transmitted disease, the best way to fight them is to wash your hands with soap.
A form of E. coli lives in every human gut, but some strains, usually ingested in shit-contaminated food, can paralyze and kill. For Americans, the commonest carriers are hamburgers.
Feces have always been important for doctors. Inspecting them used to be standard treatment, and prescribing them was also common: Roman writer Pliny thought fresh excrement soothed wounds, while 16th century Englishmen believed a good whiff of excremental odor could ward off plague.
A stool consists of 65 percent water, 5–10 percent nitrogen, 10–20 percent soluble substances and 10–20 percent “ash” (a physiological term for the portion of consumed food that cannot be digested), all coated with mucus. Beyond that, the makeup of your excreta is a lottery, depending on the gut flora inherited from your parents; diet; where you live; state of health; and alcohol consumption. Its color may also vary: black shit indicates a bleeding ulcer, for example, while over-consumption of certain colored vegetables or ice cream could turn it green.
The weight and size of your feces don’t depend on your weight and size. As a ratio of their bodyweight, children’s poop is larger than adults. Diet however is crucial. Eating a fiber-rich diet, as South Asians do, produces more and heavier shit, while rich, refined fatty food like white bread, and certain meats and cheese produce smaller, denser varieties.
Your stool’s shape can indicate the state of your intestinal health. In an attempt to assist doctors, Dr. Ken Heaton of Bristol University in the UK devised the Bristol Stool Chart in 1997. Type one is hard, nut-like lumps; type seven is entirely liquid. Types one and two can indicate constipation; the higher-range stools could indicate diarrhea. You’re aiming for types three or four: excrete a sausage or snake-shape and you shouldn’t even need to wipe.