Mary Roach - Gulp

Mike Jones explains the arousal-by-stretching phenomenon by way of shared wiring. Defecation, orgasm, and arousal all fall under the purview of the sacral nerves. The massive vaginal stretch of childbirth sometimes produces orgasm, as can, at least in one diverting case study, defecation. Jeremy Agnew, in his 1985 paper “Some Anatomical and Physiological Aspects of Anal Sexual Practices,” wrote, “Contraction of the anus upon manipulation of the clitoris during physical examination is often observed by gynecologists.” Which kind of makes you wonder who Jeremy Agnew’s gynecologist was.

I have a question, and forgive me in advance. If filling the rectum with stones or concrete or arms can be a direct flight to ecstasy, why is constipation so universally a misery? Or is it? Are there people who derive sexual gratification from self-manufactured filler? Is the urge to go ever complicated by the urge to come?

I accosted William Whitehead with these questions. “A lot of visceral sensation seems to follow what’s been called a kind of Janus-faced function,” he managed—meaning pleasure and pain on different sides of the same head. He had sidestepped the constipation question. Not wishing to be a pain in the parts, I lobbed the question over to Mike Jones’s court.

“I think that the difference is that constipation is very rarely a self-determined event.” What Jones was getting at, I believe, is that sexual arousal depends on the players and the circumstances. The difference between Ping-Pong balls and scybala is the difference between sexual intercourse and getting a Pap smear.

Most fans of back-door activities probably enjoy a combo plate of rectal and anal sensations. Why else would someone have invented the anal violin? Agnew describes this unusual item as an ivory ball with catgut attached. “The ball is inserted into the rectum while a partner strokes the attached string with a type of violin bow, thus transmitting vibrations to the anal sensory end organs,” and puzzlement to the neighbors.

I never asked Rodriguez my question about “masked anal manipulation.” (The term refers to gratification of anal carnality via seemingly nonsexual behaviors. It does not necessarily, though surely can, involve a Lone Ranger getup.) It seems to me no masking is needed: that men in prison can be fairly open about their anal intents. If a prisoner puts an iPhone up his rectum, it’s because he wants to use it or sell it. If, on the other hand, he puts a toilet brush up there, he is seeking something more ineffable. Rodriguez told me about this one. “They took him out on a gurney, man. The handle was sticking out.”

I told Rodriguez about the 402 stones.

“The rectum will stretch. Believe that.”

THOUGH THERE HAS yet to be a case of a terrorist detonating a bomb in his alimentary canal, explosions inside the digestive tract are well documented. Flatus is mostly hydrogen, mixed with (in a third of us) methane. Both gases are flammable, a fact that occasionally becomes obvious in the endoscopy suite. As in volume 36 of the journal Endoscopy : “A loud explosion occurred in the colon immediately after the first spark induced by argon plasma coagulation.” And again in volume 39: “Immediately on starting to treat the first of these angiodysplasias with APC, a loud gas explosion took place.” And finally in Gastrointestinal Endoscopy , volume 67: “The authors reported that a loud gas explosion was heard during the treatment of the first of the angiodysplasias.” Intestinal gas is not always funny.

LONG BEFORE ANYONE put a cautering wand up anyone else’s patoot, the dangers of flammable [80] Flammable is a safety-conscious version of inflammable . In the 1920s, the National Fire Protection Association urged the change out of concern that people were interpreting the prefix in to mean “not”—as it does in insane . Though surely those same people must have wondered why it was necessary to warn of the presence of gas that will not burst into flame . bowel gas were well known. If you let manure sit, as any farmer can tell you, bacteria will break it down into more elemental components. Some of these are of value to farmers as fertilizer, which they can pump from their manure pit out onto their crops. [81] “Work with your neighbors,” urges the Southeast Iowa Snouts & Tails Newsletter . “Inquire about any outdoor events in the neighborhood such as weddings, cookouts and such to avoid manure application prior to those events.” Unless your neighbors are also swine farmers, who apparently don’t mind that sort of thing. The next item in the newsletter is a Manure Injection Field Demonstration “followed by a free lunch.” Others—hydrogen, say, and methane—will blow the roof off the hog barn. Here is the Safe Farm Program channeling Beatrix Potter in a methane-safety radio spot: “It has no smell. It has no color. It often lurks about, but fails to leave a trace.”

Methane and hydrogen are explosive in concentrations higher than 4 to 5 percent. The foam on liquid manure in pits is 60 percent methane. Farmers may know this, but their families sometimes don’t. Which explains why the University of Minnesota Extension Service’s farm safety curriculum includes instructions for a children’s classroom Manure Pit Display. (“You will need:… toy cow, pig, and bull [1/32 scale], an aquarium, one pound of dry composted manure… and chocolate kisses… to simulate manure on top of floor [optional].”)

Like a Manure Pit Display, the human colon is a scaled-down version of a biowaste storage tank. It is an anaerobic environment, meaning it provides the oxygen-free living that methane-producing bacteria need to thrive. It is packed with fermentable creature waste. As they do in manure pits, bacteria break down the waste in order to live off it, creating gaseous by-products in the process. Most voluminously, bacteria make hydrogen. Their gas becomes your gas. Up to 80 percent of flatus is hydrogen. About a third of us also harbor bacteria that produce methane—a key component in the “natural gas” supplied by utility companies. (At least two-thirds of us harbor a belief that methane producers’ farts burn blue, like the pilot light on a gas stove. Sadly, a YouTube search unearthed no evidence.)

The flammability of methane and hydrogen is part of the reason for the seeming overkill of protracted bowel-cleansing that precedes a colonoscopy. When gastroenterologists find a polyp during a screening, they will usually remove it while they’re in there, using a snare with an electrocoagulating option to staunch the bleeding. They do not want to worry about igniting a rogue pocket of combustible gas—as happened in France, in the summer of 1977, to fatal effect.

At a university hospital in Nancy, a sixty-nine-year-old man arrived at the Services des Maladies de l’Appareil Digestif (French for “Gastroenterology Department”). With the current set to 4, the doctor began a simple polypectomy. Eight seconds into it, an explosion was heard. “The patient jerked upwards off the endoscopy table,” reads the case report, and the colonoscope was “completely ejected” (French for “launched from the rectum like a torpedo”).

What was strange was that the Frenchman had followed his colonoscopy prep instructions to the letter. The culprit, in this case, had been the laxative. The staff had prescribed a solution of mannitol, a sugar alcohol similar to sorbitol, the likely laxative agent in prunes. Though the man’s colon contained no fecal matter, it still contained bacteria, hungry bacteria that feasted on the mannitol and produced enough hydrogen to set the stage for an internal Hindenburg scenario. A study done five years later found potentially explosive concentrations of hydrogen or methane, or both, in six out of ten patients prepped with mannitol.