Gulp: Adventures on the Alimentary Canal

“I remember, for my last book, talking to the public-affairs staff who choose what to stream on NASA TV. The cameras are often parked on the comings and goings of Mission Control. If someone spots a staffer eating lunch at his desk, the camera is quickly repositioned. In a restaurant setting, conviviality distracts us from the biological reality of nutrient intake and oral processing. But a man alone with a sandwich appears as what he is: an organism satisfying a need. As with other bodily imperatives, we’d rather not be watched. Feeding, and even more so its unsavory correlates, are as much taboos as mating and death.”

Roach uses concrete examples from NASA TV to illustrate society’s discomfort with the biological aspects of eating, demonstrating how social context masks the fundamental nature of feeding. The contrast between communal dining and solitary eating reveals how “conviviality distracts us from the biological reality,” showing that humans prefer to romanticize necessary bodily functions rather than confront their animal nature. By comparing eating to “mating and death,” Roach places digestion among humanity’s most fundamental taboos, establishing the controversial territory her book will explore. This passage directly addresses the theme of Exploring Taboos Around Food and Digestion by exposing the cultural mechanisms that hide the biological reality of eating. The anecdote serves Roach’s larger argument that scientific understanding requires confronting uncomfortable truths about human biology that society typically conceals.

“Humans perceive five tastes—sweet, bitter, salty, sour, and umami (brothy)—and an almost infinite number of smells. Eighty to ninety percent of the sensory experience of eating is olfaction. Langstaff could throw away her tongue and still do a reasonable facsimile of her job.”

Roach uses stark numerical contrasts—five versus “almost infinite”—to emphasize the dramatic disparity between taste and smell capabilities. The hyperbolic image of Langstaff discarding her tongue creates a memorable and slightly absurd visual that underscores how fundamentally misunderstood the eating experience is by most people. This rhetorical strategy of pairing scientific precision with vivid, almost comic imagery demonstrates Roach’s ability to make complex physiological concepts accessible without sacrificing accuracy. This passage exemplifies Gulp’s argument that digestion involves processes far more intricate and counterintuitive than people typically realize.

“We consider tasting to be a hedonic pursuit, but in much of the animal kingdom, as well as in our own prehistory, the role of taste was more functional than sensual. Taste, like smell, is a doorman for the digestive tract, a chemical scan for possibly dangerous (bitter, sour) elements and desirable (salty, sweet) nutrients.”

Roach uses the metaphor of a “doorman” to characterize taste as a protective mechanism rather than a source of pleasure. The juxtaposition between “hedonic” and “functional” highlights how humans have elevated taste beyond its biological purpose through cultural evolution. Her personification of taste as a security guard creates an accessible way to understand complex evolutionary biology.

“Cats, unlike dogs and other omnivores, can’t taste sweetness. There’s no need, since the cat’s diet in the wild contains almost nothing in the way of carbohydrates (which include simple sugars). Either cats never had the gene for detecting sweet, or they lost it somewhere down the evolutionary road.”

The logical connection between diet composition and taste perception illustrates the precision of evolutionary adaptation. This example supports the theme of The Wonders of the Alimentary Canal by showing how different species develop remarkably specific digestive capabilities based on their ecological niches.

“Interpreting animals’ eating behaviors is tricky. By way of example, one of the highest compliments a dog can pay its food is to vomit. When a ‘gulper,’ to use Pat Moeller’s terminology, is excited by the aroma of a food, it will wolf down too much too fast. The stomach overfills, and the meal is reflexively sent back up to avoid any chance of a rupture. ‘No consumer likes that, but it’s the best indication that the dog just loved it.’”

Roach uses irony to highlight how human interpretations of animal behavior often contradict biological reality. The counterintuitive notion that vomiting represents a “compliment” challenges assumptions about digestive processes. The quoted expert opinion provides authoritative support while maintaining the book’s humorous tone. This passage exemplifies the theme of Exploring Taboos Around Food and Digestion by presenting vomiting—typically considered disgusting—as a positive indicator of an animal’s appetite.

“The well-known, long-standing cheapness of offal, Mead wrote, condemned it to the wordy category ‘edible for human beings but not by own kind of human being.’ Eating organs, in 1943, could degrade one’s social standing. Americans preferred bland preparations of muscle meat partly because for as long as they could recall, that’s what the upper class ate.”

Roach uses Margaret Mead’s research to illustrate how food choices reflect social hierarchies rather than nutritional logic. The phrase “edible for human beings but not by own kind of human being” reveals the arbitrary nature of food taboos, highlighting how cultural conditioning creates artificial distinctions between acceptable and unacceptable foods. The reference to “upper class” eating habits demonstrates how dietary preferences function as markers of social status, with Americans rejecting nutritious organ meats simply because they were associated with poverty. This quote connects to the theme of Exploring Taboos Around Food and Digestion by revealing how social prejudices, rather than biological necessity, can shape what humans consider edible.

“Unlike filets and stewing meats, organs look like what they are: body parts. That’s another reason we resist them. ‘Organs,’ says Rozin, ‘remind us of what we have in common with animals.’ In the same way a corpse spawns thoughts of mortality, tongues and tripe send an unwelcome message: you too are an organism, a chewing, digesting sack of guts.”

Roach uses psychologist Paul Rozin’s research to explore the psychological basis of food disgust, illustrating how organs force humans to confront uncomfortable truths about their animal nature. The phrase “chewing, digesting sack of guts” uses deliberately crude language that mirrors the visceral discomfort people feel when confronted with recognizable body parts. The comparison between organs and corpses connects food aversion to anxiety about mortality, suggesting that dietary taboos serve as psychological defense mechanisms.

“What I am getting at is that there is a point at which efficiency crosses over into lunacy, and the savings in money or resources cease to be worthwhile in light of the price paid in other ways. Horace Fletcher danced around that point his whole career. What amazes me is the degree to which he was taken seriously.”

Roach uses the metaphor of “dancing around” to characterize Fletcher’s relationship with rationality, suggesting he constantly approached but never fully recognized the boundary between reasonable practice and obsessive behavior. The phrase “crosses over into lunacy” creates a stark contrast between efficiency and madness, establishing a clear threshold that Fletcher repeatedly violated. Her expression of amazement functions as both genuine bewilderment and subtle criticism of the scientific establishment’s willingness to embrace pseudoscientific theories. This quote exemplifies the theme of Scientific Curiosity and the Ethics of Digestion Research by examining how legitimate scientific interest can be exploited by charlatans who prey on society’s desire for simple solutions to complex physiological processes.

“The human digestive tract has evolved to extract the maximum it can from the food ingested, Faulks said, and that is probably all it needs. ‘Nutritional science is dogged by the idea that if some is good, more is better,’ he said, ‘and this has led to the belief that we should endeavor to extract as much as possible of whichever fashionable component is in vogue. This is to ignore evolutionary biology and the imperative of survival.’”

Roach presents expert testimony that uses evolutionary logic to debunk the fundamental premise behind extreme chewing practices, contrasting millions of years of natural selection with modern faddish thinking. Scientist Richard Faulks’s reference to “evolutionary biology and the imperative of survival” invokes the authority of natural processes over human intervention, suggesting that attempts to improve upon evolution are both arrogant and unnecessary. The clinical tone of this expert opinion provides scientific credibility to counter Fletcher’s pseudoscientific claims.

“I am honestly curious about saliva, but I am also curious about obsession and its role in scientific inquiry. I think it’s fair to say that some degree of obsession is a requisite for good science, and certainly for scientific breakthrough. Had I been able to spend time with William Beaumont in his lab, I imagine that my initial negative impressions of him and his work—the unorthodoxy of his methods, the seeming insensitivity to St. Martin—would have fallen away, and in their place I would have felt a measure of respect for the inventiveness and dedication at the core of what he did. I would have pitied St. Martin, not because Beaumont treated him badly, but because life had—because the circumstances of his birth afforded no opportunity to be William Beaumont.”

Roach uses first-person reflection to examine the complex relationship between scientific dedication and ethical conduct, revealing her own evolution as both researcher and moral observer. She demonstrates how Scientific Curiosity and the Ethics of Digestion Research extends beyond mere fascination with bodily functions to include examination of the researchers themselves. Her hypothetical scenario about spending time with Beaumont uses conditional language to explore how proximity to passionate scientists might alter one’s moral judgments, suggesting that scientific obsession can be both admirable and troubling.

“The Salivette makes an unmistakable point: your parotid glands don’t care what you chew. There is nothing remotely foodlike about superabsorbent cotton, yet the parotids gamely set to work. They are your faithful servants. Whatever you decide to eat, boss, I will help you get it down.”

Roach uses personification to transform the parotid glands into dedicated workers. This anthropomorphic characterization makes the complex biological process of salivation more accessible. The italicized dialogue emphasizes the glands’ unwavering commitment to their function, regardless of what triggers them. The contrast between “superabsorbent cotton” and actual food highlights how mechanical and automatic digestive processes truly are.

“Paul Rozin has given a lot of thought to what he calls the psychological microanatomy of the mouth: Where, precisely, is the boundary between self and nonself? If you stick your tongue out of your mouth while eating and then withdraw it, does the ensalivated food now disgust you? It does not. The border of the self extends the distance of the tongue’s reach. The lips too are considered an extension of the mouth’s interior, and thus are part of the self. Though culture shifts the boundaries.”

Roach presents a thought experiment that challenges readers to examine their own psychological boundaries regarding bodily fluids and disgust. The rhetorical question engages readers directly, forcing them to confront their own reactions and assumptions about what constitutes the “self” versus the external world. The phrase “psychological microanatomy” creates a scientific framework for understanding deeply personal and cultural reactions to the human body. This analysis of disgust and cultural boundaries demonstrates the theme of Exploring Taboos Around Food and Digestion, showing how seemingly universal reactions are actually shaped by psychological and cultural factors rather than biological necessity alone.

“Crispness and crunch appeal to us because they signal freshness. Old, rotting, mushy produce can make you ill. At the very least, it has lost much of its nutritional vim. So it makes sense that humans evolved a preference for crisp and crunchy foods. To a certain extent we eat with our ears. The sound made by biting off a piece of carrot—more so than its taste or smell—communicates freshness.”

Roach uses scientific reasoning to explain an everyday sensory experience, demonstrating how evolutionary biology shapes modern eating habits. The metaphorical phrase “we eat with our ears” transforms the conventional understanding of taste from a purely gustatory experience into a multi-sensory phenomenon that includes auditory cues. By connecting the seemingly simple preference for crunchy foods to survival mechanisms, Roach illustrates how deeply ingrained biological programming influences behavior. This analysis exemplifies Gulp’s broader mission to reveal the sophisticated biological systems that operate beneath conscious awareness during the most mundane acts of eating.

“What no one in Hunter’s day realized is that the organ swiftly rebuilds what it breaks down. A healthy adult has a new stomach lining every three days. (More clever stomach tricks: key components of gastric acid are secreted separately, lest they ravage the cells that manufacture them.)”

The phrase “clever stomach tricks” uses personification, attributing intelligence and cunning to an organ. The casual tone contrasts sharply with the technical medical knowledge being conveyed. The passage connects to Gulp’s larger point that the digestive system contains remarkable adaptations that most people never consider, encouraging people to appreciate the complex engineering of their own bodies.

“People who understand anatomy are often cowed by the feats of the lowly anus. ‘Think of it,’ said Robert Rosenbluth, a physician whose acquaintance I made at the start of this book. ‘No engineer could design something as multifunctional and fine-tuned as an anus. To call someone an asshole is really bragging him up.’”

Roach uses this quote to demonstrate how scientific knowledge can completely reframe one’s understanding of supposedly crude or embarrassing body parts. The juxtaposition between the clinical term “multifunctional and fine-tuned” and the colloquial insult “asshole” creates ironic humor that challenges preconceptions about bodily functions. Rosenbluth’s expert testimony serves as authoritative evidence for the remarkable engineering of human anatomy, while his playful conclusion about the insult being inadvertently complimentary uses wordplay to make the scientific point memorable. The quote reflects the theme of Exploring Taboos Around Food and Digestion. The passage exemplifies Gulp’s argument that the human digestive system deserves scientific respect and wonder rather than shame or disgust, encouraging readers to approach their own biology with curiosity rather than embarrassment.

“Outside the body, intestinal hydrogen and methane pose no danger. The act of passing flatus dilutes the gases, mixing them with the air in the room and lowering the concentration to levels well below combustibility. As anyone who has typed pyroflatulence into YouTube is aware, the match would have to contact the gas the second it’s blown from the body.”

The clinical language of “intestinal hydrogen and methane” contrasts with the colloquial reference to YouTube searches for pyroflatulence, creating a juxtaposition that both educates and entertains. Roach normalizes curiosity about taboo subjects while providing factual information about the human body. The parenthetical tone suggests shared knowledge between author and reader, creating intimacy around a topic typically considered inappropriate for polite conversation. This approach exemplifies the theme of Exploring Taboos Around Food and Digestion by transforming potentially crude subject matter into legitimate scientific inquiry while maintaining the humor that makes such topics approachable.

“She told me about a woman whose boyfriend kept pulling over to ‘check the air in the tires.’ More typically, it is women, mostly of my mother’s generation, who don’t want anyone, ever, under any circumstances, to hear them. Like the gassy nun at the Holy Spirit—Corpus Christi Monastery, who had called earlier in the day.”

Roach uses humor and euphemism to illustrate the profound social shame surrounding natural bodily functions, particularly for women. The anecdote about a boyfriend’s tire-checking excuse creates comedic relief while highlighting the lengths people go to hide their flatulence. The repetitive phrase “anyone, ever, under any circumstances” emphasizes the absoluteness of this social anxiety. The inclusion of the nun adds both humor and universality, suggesting that even those devoted to spiritual matters cannot escape these earthly embarrassments. This passage connects to the theme of Exploring Taboos Around Food and Digestion, demonstrating how cultural conditioning creates shame around natural biological processes.

“What amazed me about Magendie, aside from his zest for gore, was this: using instruments available in 1814, he was able to detect hydrogen sulfide, a gas that typically makes up one-ten-thousandth of the gas produced in the human colon.”

Roach expresses genuine scientific admiration while using dark humor to acknowledge the macabre nature of early digestive research. The phrase “zest for gore” creates a deliberately casual tone that contrasts with the sophisticated scientific achievement she describes, highlighting how scientific progress often spurs researchers to push beyond conventional boundaries of comfort and propriety. The specific measurement “one-ten-thousandth” emphasizes the remarkable precision achieved with primitive tools, showcasing human ingenuity in the pursuit of knowledge. This quote embodies the theme of Scientific Curiosity and the Ethics of Digestion Research, illustrating how researchers throughout history have been willing to explore uncomfortable or disturbing territory to advance understanding. The passage supports the book’s broader celebration of scientists who investigate the less glamorous aspects of human biology, demonstrating that meaningful discoveries often emerge from studying what society prefers to ignore.

“Hydrogen sulfide is as lethal, molecule for molecule, as cyanide. This may explain why humans evolved such exquisite sensitivity to its smell. Repellent odors are unpleasant but often helpful in terms of not dying.”

The juxtaposition of hydrogen sulfide with cyanide, a notorious poison, emphasizes the gas’s potential danger while the phrase “exquisite sensitivity” elevates human olfactory abilities to something refined and purposeful. The casual tone in “helpful in terms of not dying” uses humorous understatement to make complex evolutionary biology accessible.

“The moral of the story is this: It takes an ill-advised mix of ignorance, arrogance, and profit motive to dismiss the wisdom of the human body in favor of some random notion you’ve hatched or heard and branded as true. By wisdom I mean the collective improvements of millions of years of evolution. The mind objects strongly to shit, but the body has no idea what we’re on about.”

Roach contrasts “random notion” with “wisdom” to highlight the difference between unfounded beliefs and evolutionary truth. Her blunt use of “shit” alongside clinical language creates deliberate tonal contrast, reinforcing the theme of Exploring Taboos Around Food and Digestion by directly confronting social discomfort with biological reality. This quote encapsulates the book’s overarching message that scientific understanding should triumph over cultural squeamishness, and that the alimentary canal represents evolutionary wisdom rather than something requiring human improvement.

“In some neighborhoods of the animal kingdom, your own is a regular second course. For rodents and rabbits, in whom vitamins B and K are produced exclusively in the colon (by bacteria that live there), the self-manufactured pellet is a large, soft daily vitamin.”

Roach uses euphemistic language and playful metaphors to transform a potentially disgusting topic into accessible scientific information. The phrase “your own” delicately refers to feces without using crude terminology, while “second course” reframes autocoprophagia as a dining experience. The metaphor of calling fecal pellets a “daily vitamin” transforms waste into medicine, highlighting the nutritional necessity of this behavior. This approach exemplifies the theme of Exploring Taboos Around Food and Digestion.

“I recall reading in one of Charles Tyrrell’s books that advances in medical knowledge about the colon had, historically, been hobbled by the organ’s repulsiveness. Eighteenth- and nineteenth-century dissectors and anatomy instructors would, he claimed, promptly cut the lower bowel out of the cadaver and throw it away, ‘on account of its scent-bag propensities and nastiness.’ Michael Sappol, a historian with the National Library of Medicine who has written extensively on the history of anatomy, said he’d heard this too. Leading me to wonder: Does distaste slow progress in treating diseases of the bowel? Does the excretion taboo discourage research, discussion, media attention?”

Roach uses rhetorical questions to transform a historical observation into a broader inquiry about how social squeamishness affects scientific progress. The euphemistic phrase “scent-bag propensities and nastiness” reflects the Victorian-era discomfort with bodily functions that Roach argues has hindered medical advancement. By contrasting the clinical language of modern medicine with the judgmental terminology of past centuries, Roach demonstrates how cultural attitudes can create blind spots in scientific research. The progression from historical fact to contemporary questioning illustrates Roach’s investigative method throughout Gulp. This passage exemplifies the theme of Exploring Taboos Around Food and Digestion, showing how societal discomfort with certain bodily processes has created gaps in medical knowledge that persist today.

“As regards bacteria in general, a radical shift in thinking is under way. For starters, there are way more of them than you. For every one cell of your body, there are nine (smaller) cells of bacteria. Khoruts takes issue with the them-versus-you mentality. ‘Bacteria represent a metabolically active organ in our bodies.’ They are you. You are them. ‘It’s a philosophical question. Who owns who?’”

Roach uses Dr. Khoruts’s perspective to challenge fundamental assumptions about human identity and autonomy through scientific revelation. The escalating pronouncements—from numerical comparison to philosophical questioning—demonstrate how digestive science forces readers to reconsider basic concepts of selfhood. The italicized emphasis on “are” reinforces the startling nature of this biological reality, while the final rhetorical question transforms scientific fact into existential inquiry.