Passing gas is an art and science Why can't we talk out of our rears? Are those movie explosions possible? A scientist puts farts under a microscope

Some people possess gifts so extraordinary that they define what is possible for our species. Such a man was Frenchman Joseph Pujol (1857– 1945), stage name “Le Pétomane.” Pujol’s unique gift was based on his ability to “inhale” through his rectum, an act accomplished by expanding his abdomen while ceasing to breathe through his nose and mouth. Air thus inhaled could be exhaled with force sufficient to extinguish a candle from a distance of a foot— no mean feat. But such tricks were neither the true measure of his artistry nor, as we will learn, his unappreciated contribution to science.

Pujol’s breakthrough came as a child playing on the beach when he was hit by a wave of cold water. He was startled and somehow sucked sea water into his rectum. Young Joseph, being a curious lad of experimental bent, soon discovered that he could inhale air as well as seawater though his rectum, and could exhale this air in a controlled manner. Unlike lesser men, Pujol was an entrepreneur who appreciated the comic and musical potential of a controllable anal air flow that lasted ten to fifteen seconds. He honed his craft in the provinces before setting out for Paris and auditioning for an astonished Charles Zidler, the manager of the Moulin Rouge, the world’s most famous nightclub.

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Pujol was a direct sort who believed in immediately getting down to business in his interview. After a traditional introduction, he dropped his trousers, dipped his bottom into a large washbowl in Zidler’s office, and sucked the water into his rectum, then promptly refilled the bowl to cleanse his instrument. This is the kind of job interview that’s likely to be a deal maker or deal breaker. In Pujol’s case, it succeeded wonderfully and led to one of the most remarkable careers in show business. History does not record whether Pujol’s interview involved another of his feats, expelling water from his rectum in a mighty jet that could reach twelve to sixteen feet, but he did demonstrate the vocal range of his instrument, from tenor to baritone. We will follow Joseph Pujol’s career under his stage name, Le Pétomane— literally, “fartomaniac.”

Le Pétomane’s act was full of novelty, comedy, and virtuosity. At his peak, Le Pétomane easily outearned the great actress Sarah Bernhardt, his closest contender. And what was the act of this artist who “pays no author’s royalties”? He would begin with a series of ordinary farts, describing each in turn— a little girl, a mother-in-law, a bride on her wedding night (weak) and on the morning after (loud), tearing cloth, cannon fire, and thunder. With a tube inserted in his rectum, he would smoke a cigarette or attach a flute and play tunes. But his real artistry was accomplished au naturel.

Le Pétomane’s repertoire included animal sounds— a rooster crowing, a puppy, a dog with its tail caught in a door, a blackbird, an owl, a duck, bees, a tomcat, a toad, a pig, and musical instruments including violin, bass, and trombone. The climax of Le Pétomane’s performance was a stirring rendition of “La Marseillaise” that brought down the house. He made audiences delirious with joy, writhing in their seats, tears streaming, with some fashionably dressed and corseted women so overcome that they were carried into hallways to be revived. Amazingly, no part of his performance was faked, as he once demonstrated in the nude before a panel of earnest and curious physicians.

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Sadly, we cannot experience Le Pétomane’s artistry because recordings of his act are unavailable, although one wax cylinder recording is rumored to exist. And he was born too late to win a fan in Mozart, who thought long and hard about flatulence, and who might well have been inspired to compose a concerto for Le Pétomane’s very special instrument. Certainly, Saint Augustine (AD 354–430) would have been impressed by Le Pétomane. In his City of God (Book XIV, Chapter 24), this pious advocate of willpower claimed knowledge of someone with such control of his rectum that he could break wind continuously at will and produce the effect of singing. To Augustine, Le Pétomane would have been a spiritual revelation. To those of us with more scientific interests, we are left wondering how Le Pétomane would have fared if he had turned his virtuosity to buttspeak— speaking through his rectum. Granted, buttspeak does seem a very dark horse in the vocal evolutionary sweepstakes, but looking at the possibilities of this option of speech origin is informative.

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My foray into fart science is a bit timid. The mere inclusion of the topic threatens to lower my intellectual tone. A confluence of circumstances forced the subject on me. While recording laughter for an earlier study, one of my subjects laughed so hard that he farted. Since I already had it on tape and was in a sound lab, why not check out the acoustics of farting? This was a defining moment. Would I lose resolve, as did Galileo when he was “shown the instruments” by his inquisitors? With tenure safely in hand, I forged ahead. What started as a playful acoustic analysis led to the quite serious consideration of why we speak through the mouth instead of the rectum. Along the way, I discovered a quirky and amusing literature that may elevate the status of the lowly fart as a topic in scientific discourse.

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Throughout the ages, farting (flatulation) has generated jokes, folklore, etiquette, and a few legal sanctions, but little research. The legendary Hippocrates (460–377 BCE) considered the medical affliction of too much gas in The Winds, advising, “It is better to let it pass with noise than to be intercepted and accumulated internally” (1.24–25). The topic has been treated more often in popular fare, including the humorous writings of Geoffrey Chaucer, Benjamin Franklin, and Mark Twain. Fart jokes earn a place in the opening scene of Aristophanes’ The Clouds and the memorable closing scene of “The Miller’s Tale” in Chaucer’s The Canterbury Tales. Although passing gas is usually considered ill-mannered, it’s usually laughed off as a minor offense. But this has not always been the case. The Roman Empire once had laws against farting in public places, a sanction that must have caused a lot of fanning and finger-pointing in the Forum. The law was lifted during the reign of Claudius, one of the most flatulent of emperors.

Consider the sad fate of Pu Sao of the Tikopia in Polynesia, who was so overcome with shame after farting in the presence of the chief that he committed suicide by climbing a palm tree and impaling himself through the rectum with a sharply pointed branch. Sanctions are less severe among the Chagga of Tanzania, but feminists have a lot of work to do there. If a husband breaks wind, the wife must pretend that it was really she who discharged, and she must submit to scolding about it. Failure to accept responsibility can cost the negligent wife three barrels of beer. Unlike the Chagga, modern Americans are pretty much adrift regarding farting etiquette, with manners mavens such as Judith Martin (aka “Miss Manners”) offering no guidance.

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Although farting etiquette is varied, the medical establishment generally supports Hippocrates’ position that it is better to let gas out than hold it in. Almost two thousand years later, the always surprising and encyclopedic Michel Eyquem de Montaigne in his essay “Of the Force of Imagination” notes forbiddingly that “God alone knows how many times our bellies, by the refusal of one single fart, have brought us to the door of an agonizing death.” Indeed! Modern medicine offers some support, reporting that flatus retention is the major factor in diverticular disease.

The origin of the gas that powers farting has been the subject of speculation since ancient times. Ancient encyclopedist Pliny the Elder (AD 23–79) claimed that lettuce breaks up flatulence but garlic, leeks, and onions cause it, noting that Democritus (460–370 BC) totally opposed turnips as food because they cause flatulence. Two millennia later, we have entered the golden age of flatulence research. Analytical chemists tell us that at least 99 percent of bowel gas is composed of nitrogen, oxygen, carbon dioxide, hydrogen, and methane (swamp gas), with all but oxygen and nitrogen arising from processes within the gut. None of these flatus gases can be detected by smell; the odiferous component must come from other trace gases produced by gut bacteria.

Methane is the gas that sustains the odd male ritual of fart lighting, the ignition of farts by a match placed near the anus. The resulting methane jet produces a lovely blue flame, quite unlike the orange flame portrayed in Jim Carrey’s film "Dumb and Dumber, "the flatus-fueled conflagration in "Dennis the Menace," and more recently that seen in Eddie Murphy’s "Nutty Professor II: The Klumps." Fortunately, only about one third of the population can generate combustible levels of methane. On a more serious note, a gassy gut can be fatal, as it was for a patient having a colonic polyp cauterized. An electric spark caused the patient’s bowels to detonate, blasting out the colonoscope and ripping a six- inch hole in the patient’s large intestine.10 Le Pétomane’s farts would not have been a fire hazard— they were composed solely of noncombustible normal air sucked into his rectum.

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Farting is an acoustic as well as chemical event, and I wanted to subject it to the type of analysis used previously for laughs, farting and belching coughs, sneezes, and hiccups. It should be easy to collect fart sounds for analysis; the average twenty- to thirty-year-old farts about thirteen times per day. However, not wishing to pursue the indelicate task of collecting further data, I will confine my analysis to the already collected sample from the laughing subject.

The bottom trace of a fart's acoustic structure is a sound spectrum that shows strong harmonic structure, as reflected in the regular stack of frequency bands that are multiples of a fundamental frequency of around 150 Hz at mid-burst. The fart has a tonal quality and is clearly not a noisy blast with a random distribution of frequencies. The fart also has a periodic, pulsatile quality (amplitude modulation). A raspberry or Bronx cheer, produced by placing the tongue between the lips and blowing, makes a similar sound. Farts lack the structural stereotypy of laughs, coughs, sneezes, and hiccups, and their duration is determined by the highly variable supply of available gas. The artistry of Le Pétomane is testimony to the flexibility of this channel of communication.

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We now rejoin the evaluation of buttspeak as communication medium. This question is not as outlandish as it seems and involves central issues in vocal production and evolution. Before you prematurely reject the possibility, consider the evidence. The traditional vocal apparatus of humans is not a paragon of biological elegance. No part of it evolved exclusively in the service of sound making. We speak through the same toothy orifice through which we breathe, eat, drink, and vomit, and the vocal folds (cords) used for sound production are simply two flaps of muscular tissue that act as a seal to keep food and drink out of the airway when swallowing. We choke when failing to operate this clunky, complicated, and delicate apparatus correctly. Sometimes it malfunctions on its own.

The lungs and muscles of the thorax are bellows that propel air through the vocal folds, which respond by vibrating, producing a buzzing sound like a reed in a woodwind instrument. The upper vocal tract (throat, mouth, tongue, teeth, lips) provides resonance chambers and a means of shaping the buzzing sounds of the vocal folds. We “play” this biological instrument to produce speech.

Given the curious heritage of our vocal apparatus, buttspeak does not seem so far-fetched. If you use the abdomen and colon for the air reserve and bellows instead of the lungs and thorax, and the seal of the anal sphincter as the vibrating element instead of that of the vocal folds, you have a start toward a viable speech generator. With apologies to Louis Armstrong and Wynton Marsalis, the anal sphincter functions like the lips of a trumpet player buzzing into a mouthpiece, but in farting, the rest of the trumpet, the part that shapes the sound, is missing. (An adventurous musical acquaintance acknowledged that a tone can indeed be produced by farting into a trumpet, creating a middle C, but further details were not forthcoming from this wary pioneer of the butt-trumpet.) The traditional vocal tract offers much more flexibility to shape and tune an utterance produced by a vibrating sound source than the less traditional one available to Le Pétomane. He could honk out the tune of “La Marseillaise” but not its rousing lyrics.

Having made the case that farting could provide a novel though limited channel of communication, we can question whether any animals actually exploit this unlikely aural niche. So far, signaling by fart is reported only in certain herring. The breakthrough research appears in a paper cryptically titled “Pacific and Atlantic Herring Produce Burst Pulse Sounds.” The work earned Ben Wilson and colleagues at the Bamfield Marine Science Centre in British Columbia, Canada, the 2004 Ig Nobel Prize in biology. The scientists became curious about the origin of strange rasping noises produced at night by captive herring under observation in a tank, and discovered that they were fish farts. The fish gulp air at the surface, store it in their swim bladder, and release it from a duct in their anus, producing a high- frequency burst up to 22,000 Hz. (Human hearing ranges from 20 Hz to 20,000 Hz.) Their next insight was that the farts are signals that may bring fish together and assist in evading predators. But signaling may have a price: predators such as killer whales may also be listening to flatulent herring and home in on the signal. The herring fart by night, but not by day, when they rely on visual instead of auditory information.

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Belching, like farting, is another potential path not taken in the course of human speech evolution. The sound of belching (eructation) is caused by the vibration of the upper esophageal sphincter as gas passes through it. This sphincter reflexively opens during swallowing, then closes, providing a seal against backflow from the esophagus into the pharynx. A lot of sonic energy can be produced by a belch— the current Guinness World Record is 118 decibels, set by Paul Hunn of London, England, in 2000.12 This is louder than a chain saw at a distance of one meter.

Like the fart, belches have a strong pulsatile character as reflected in the vertical bands (amplitude modulation) of the waveform (upper) and frequency spectrum (lower), but the pulsations of the belches have a much lower frequency. The noisy sonic blast of the belch is less tonal and lacks the marked harmonic structure of the fart. Like the fart, the duration of a belch is limited by available gas.

Belching is usually caused by eating or drinking too fast and thereby swallowing air, which is subsequently expelled, causing the characteristic sound. Belches are also caused by imbibing carbonated beverages such as soft drinks or beer, in which case the expelled gas is carbon dioxide from the drink itself. Expelled gas can arise from digestive processes in the stomach or from gastroesophageal reflux. Babies are particularly prone to accumulate gas in the stomach while feeding, causing distress until the baby is burped, releasing the gas.

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Most human belches are composed of nitrogen and oxygen, the main components of swallowed air. A grazing cow, in contrast, releases up to six hundred liters of methane into the atmosphere per day. Contrary to folklore, 95 percent of this release is through burping, not flatulence. Researchers at the Commonwealth Science and Industrial Research Organization of Perth, Australia, are seeking to reduce release of this green house gas by developing an anti-methane vaccine to minimize burping and flatulence in cattle and sheep.

Ordinary, belching people can achieve a level of virtuosity that puts Le Pétomane to shame. Belched (esophageal) speech can be produced voluntarily by swallowing air and then expelling it, manipulating the sound with the vocal tract as you would with normal speech. Children sometimes entertain themselves with this vocal novelty, but it is put to serious use by people who have experienced laryngotomy. With practice, esophageal speech can be used to produce intelligible words at a rate of around five words per breath, or about 120 words per minute, in a characteristically low pitch (50–100 Hz). A less demanding way of producing the vibrations necessary for non- laryngeal speech is the electrolarynx, a small device that is held against the throat. You may have heard the robotic, machine-like quality of speech produced by people using this device.

A theme here is how sounds are produced by vibrating structures and subsequently selected and shaped for auditory communication. This is an analysis of speech evolution in disguise. The necessary vibration may come from the upper esophageal sphincter in belching, the anal sphincter in farting, or the vocal folds, the structure ultimately selected for speech. All are elastic seals set in motion when they can no longer resist the passage of gas that they restrict. Belching, farting, and speaking all use bellows to provide the pressurized air supply necessary for vibration— the thoracic cavity in belching and speaking, the rectum in farting. With human beings, whether the vibrations are produced by vocal folds, the esophagus, or an electrolarynx, the vocal tract (throat, mouth, tongue, teeth) is still used to modulate the resulting sound to create intelligible words.

Excerpted from "CURIOUS BEHAVIOR" by Robert R. Provine, published by the Belknap Press of Harvard University Press. Copyright © 2012 Robert R. Provine. Used by permission. All rights reserved.