That's Disgusting
The Raw and the Rotten (2)
Disgust is a basic human emotion, as much so as love, anger and fear. But disgust is not nearly as well understood as those more widely recognized emotions. As such there are quite divergent explanations for what we find disgusting and why. There are some advocates of what is called Darwinian Medicine who would have you believe that the emotion we call disgust is an adaptation for avoiding bad microbes, part of a “Behavioral Immune System”. Decaying carcasses, shit, vomit and such elicit the gag reflex because natural selection has ensured that we don’t get sick from that stuff. The problem with this view is that while disgust is a universal emotion, what we find disgusting isn’t. Disgust is an emotion that is quite culturally conditioned.
Many traditional cultures find menstruation disgusting enough to sequester women in that condition so that the men are not polluted. That aversion is certainly not universal though. In some cultures, the urine of men is routinely drunk, but not that of women. It’s not because women’s urine has more pathogens than men’s urine. Most of us would be disgusted by the prospect of drinking either. (A recent uptick in urine consumption in the West, based on dubious health claims, should be noted.) As for feces, 18th century missionaries were disgusted that indigenous hunter-gatherers in Baja California did not share their disgust. Instead the natives carefully picked through their own shit in search for the undigested seeds of the fruit from the pitahaya cactus. After this “second harvest,” the seeds retrieved in this way were promptly eaten again for another go at digestion.
Moreover, as any parent can attest, we are not born with a disgust response. Infants everywhere will play with vomit and shit. They must be taught not to. The disgust response doesn’t begin to develop until around age five, well after weaning. It is in the earlier years that infants are most vulnerable to diarrhea, the leading cause of infant mortality. You would think, from the perspective of Darwinian Medicine, that natural selection would have equipped infants with a proper phobia for shit, at the very least. Such is not the case, however. Parents, and broader enculturation must ensure their disgust.
The facial expression characteristics of the disgust response is a wrinkled nose and clenched teeth, which suggests that much of the disgust response is concerned with odor and taste, what counts as edible and what does not. We humans are uber-omnivores. As a species, our diets encompass by far the broadest range of foodstuffs of any mammal, any animal, for that matter. As individuals, of course, our diets are more constrained, largely in culture specific ways. Westerners, it turns out, have the most constrained diets, and Anglophone Westerners are the most finicky of all, which contributes in no small way to the popularity of television shows centered on so-called extreme foods. Southeast Asians would find this form of entertainment much less compelling.
Europeans brought their hyper-sensitive disgust response to the foreign lands they conquered and colonized around the world. The British colonizers of Australia encountered particularly alien native foods. Indigenous Australians were culturally diverse, which was reflected in their diets. But these diverse diets were uniformly disgusting to the first colonists. Even kangaroo meat was reviled, resulting in the import of domesticated sheep and cattle as a reliable supply of red meat. They were even more disgusted by the reptiles—lizards of diverse sorts, turtles and snakes-- which the natives routinely consumed. Imagine then how they reacted to the insect fare. The wichitty grub—the larva of a large moth—continues to be relished by desert inhabitants. The early colonists would gag at the mere thought of consuming them, as do most Westerners today.
And then there is the rotten, to which the advocates for a behavioral immunes system believe we should be especially well-attuned. Westerners are the standard they have in mind. But as we shall see, much that Westerners consider rotten is a perfectly healthy source of nutrition in many cultures.
Consider the plight of European explorers in the arctic. John D. Speth, an archaeologist at the University of Michigan, has collected a number of amusing anecdotes about these culinary culture clashes. One of my favorites concerns an American, George W. Mellville, who volunteered in 1879 for a mission to rescue John D. Delong, an explorer who had disappeared during an attempt to find the quickest route to the North Pole. Melville began his adventure in the Bearing Sea and traveled west, during the Arctic winter, all the way to the Lena Delta in northeastern Siberia, a distance of over 1,000 miles. By the time he arrived at the Lena, provisions were quite low and he welcomed the offer of food by the native Yakut people. Melville was obviously a hardy soul but his resilience was severely tested by the proffered fare, probably none-to-fresh caribou:
“So long as it remained frozen the meat did not exhibit the vile extent of its putridity; but directly I had taken it into my mouth it melted like butter, and at the same time gave off such a disgusting odor that I hastily relinquished my hold upon it, and the dogs captured it at a single gulp. The natives first stared in genuine astonishment to see me cast away such good food to the dogs, and then burst forth into hearty laughter at my squeamishness. But I was not to be outdone, much less ridiculed, by a Yakut, so I ordered some more, perhaps a pound of the stuff, cut up into little bits. These I swallowed like so many pills, and then gazed upon my Yakut friends in triumph; but not long, for in a little while my stomach heated the decomposed mess, an intolerable gas arose and retched me, and again I abandoned my breakfast--my loss, however, becoming the dogs gain.
Though the Yakut subsisted quite well on this diet of rotted meat, Melville, despite his best intentions and dire need of sustenance, could not avail himself of those valuable calories and nutrients. And it wasn’t because of any bacterial toxin, the meat though rotten was perfectly healthy fare, for reasons to be discussed later. Melville just literally couldn’t stomach it. Had he been raised a Yakut he would have stomached it quite well; relished it, in fact.
“Enough to Gag a Maggot”
That’s the singular expression of an acquaintance of mine from graduate school. I have not heard it uttered by anyone else before or since, except for myself on occasion. Another of his pet expressions was “a grizzly can of worms”. Both are drolly expressive of disgust but he used them in different contexts. The former was generally more food related but was also available for metaphorical extension into other domains, a mawkish movie romance, or a particularly obnoxious person, for example. To gag a maggot would seem to refer to something almost unimaginably repulsive, given their association with rotten stinking flesh. You would think that the presence of maggots is a good indication that the flesh at hand should not be eaten. But you would be wrong. Though worse for the Europeans than wichitty grubs, maggots were relished by indigenous Australians, along with the rotting carcasses they inhabited. And they were far from alone in this regard. Throughout much of human history, many hunter-gatherers (henceforth, “foragers”) have gained sustenance from decaying carcasses that were rotten and full of maggots. The Hadza of Tanzania and many northern peoples still do.
Smell is an important trigger of disgust but again what smells we find disgusting are far from universal. Europeans are particularly prone to odor-based disgust, especially sensitive to olfactory offense, as demonstrated by comparative ethnography. But there is wide variation among Europeans as to the odors deemed disgusting. Limburger cheese is one good litmus test, as was so hilariously Illustrated by Mark Twain in “The Invalid’s Story”.
The Invalid narrator was made so, indirectly, by limburger cheese. The story begins at a train station where the narrator is to board with the casket of a dead friend and convey him to his home for burial. Through sundry mistakes the casket of the dead friend is switched with another that is full of rifles. Worse, a package containing “a peculiarly mature and capable limburger cheese”, was inadvertently set on the coffin by the rifle loaders. The limburger odor was soon noticed by both the narrator and the railroad agent with which he rode. The latter remarking “phew! I reckon it aint no cinnamon ‘t Ive’d loaded up thish-yer stove with”. Of course, they thought the odor came from the narrator’s dead friend, which has the narrator feeling a bit defensive, even as he tried to suppress his own gag reflex:
“Friend of yourn”
“Yes, I said with a sigh”
He’s pretty ripe, ain’t he?
Then Thompson begins to reflect, in my favorite passage: “Sometimes it’s uncertain whether they’re really gone or not, seem gone, you know—body cold, joints limber—and so, although you think they’re gone, you really don’t know. I’ve had cases in my car. It’s perfectly awful, becuz you don’t know what minute they’ll rise up and look at you”. Then, after a brief pause: “But he ain’t in no trance! No, sir, I go bail for him”.
Later in the story, the following exchange:
“What did he die of?
I said, I didn’t know
“How long has he been dead?”
It seemed judicious to enlarge the facts to fit the probabilities; so I said,
“Two or three days.”
The engineer scoffed but the narrator took no offense. The odor became intolerable. They tried cigars and a number of other ways of masking the obnoxious odor, to no avail. In desperation—there is a raging blizzard outside—they break a window and take turns gasping for breath. Finally, they choose to stay on the outside platform in the freezing cold, rather than inhale the fragrance of the limburger cheese. To dire effect: “We were taken from the platform an hour later, frozen an insensible.” Thompson dies; the narrator never recovers; he becomes the invalid of the title, though before the fateful train ride he had been “a hale and hearty man…a man of iron, a very athlete!”.
Such is the nature of disgust that we go to extreme lengths to avoid its source, food, as much as shit. But a smell that is disgusting for some is ambrosia for others. The Durian, a treat for orangutans and many southeast Asians, has a smell that most Caucasians find disgusting. Any Malaysian hotels with even the faintest hope of attracting a Western tourist prominently post signs forbidding its presence inside. But judging by some hallways I have walked this stricture is routinely ignored. And sensibly so. We humans probably wouldn’t be dominating the earth as we do, had our ancestors been as squeamish as modern Westerners.
“Food Prep”
One hallmark of the human lineage is adaptability. But we don’t just adapt to the environment we adapt the environment to us. The adapting of the environment to us is called niche construction. We are far from singular in that capacity, but we are exceptional in the degree to which we create the environmental conditions in which we live. Hominins have been niche constructors from the get go, our justly celebrated tool-making abilities greatly facilitated this process, much of which revolved around procuring and preparing food.
The most basic form of food preparation is to smash it with a rock to break down the tougher tissues. This is useful for both plant and animal material. For plants, cellulose is particularly tough on human teeth and completely un-nutritious. When smashed, the cell walls are broken and some nutrients freed for human consumption. For animal flesh it is the meat proteins that require smash-induced tenderization. Smashing was also well suited for extracting the marrow from large bones. Bone marrow has long been a coveted food among foragers.
Cooking was a big advance over smashing; the control of fire was a milestone in human niche construction. Cooking was and remains an invaluable aid to digestion. It has long been taught that what was cooked was primarily lean red meat. Richard Wrangham has an intriguing alternative view of cooking, according to which it was more about expanding the human diet, not just utilizing existing food sources more efficiently. The new items on the expanded menu were starchy tubers, roots, bulbs and such, the parts of the plant that are underground. These resources were theretofore largely untapped because in the raw state they are un-nutritious, sometimes toxic. Cooked tubers, on the other hand provided an unprecedented source of calories, nutrients and micronutrients.
The French anthropologist, Claude Levi-Strauss, also recognized the importance of cooking; in fact, it was an organizing principle in his conception of culture as interpreted through myths. Levi-Strauss came from a completely different intellectual tradition than Wrangham, or most any anglophone for that matter. His primary inspiration was a linguistics movement, called structuralism, the father of which was another Frenchman, Ferdinand de Saussure. I was already familiar with de Saussure and sympathetic to his views when I read a translation of “Le Cru et Le Cruit”, the English version of which was called “The Raw and the Cooked” While it wasn’t easy going, it was entertaining enough to keep me interested. But to my mind, his extension of de Saussure’s linguistics to the whole of culture was a bridge to far.
Unlike most anglophone anthropologists, who pride themselves on their empiricism—letting the “facts” dictate their interpretation, Levi-Strauss thought that interpretation should be thoroughly embedded in the facts from the start. Levi-Strauss’s interpretive framework depended critically on binary oppositions, most fundamentally, that of nature and culture. This is to take a wrong turn right out of the driveway: culture is as “natural” to the human condition as digestion. In any case, the raw represents nature and the cooked represents culture according to Levi-Strauss. Secondarily, there are two forms of the cooked, the roasted and the boiled. Roasting, in which the fire’s heat is unmediated by human artifacts, is closer to nature, while boiling, which requires artifacts like pottery and pots, is more thoroughly cultural. Meat (both proteins and fats) was the food where the contrast between nature (the raw) and culture (the cooked) was particularly stark.
Another important binary opposition in his framework was between the fresh and the rotten. The category of the rotten eventually became part of his famous “culinary triangle”—along with the raw and the cooked (Figure x). For Levi-Strauss, while the cooked is culture, both the raw and the rotten represent nature. Moreover, the rotten is more natural than the raw because all edible things tend to degrade, the culinary equivalent of entropy. This is where he could have used another binary opposition, that between the bad kind of rotten and the good kind of rotten. The latter, though, doesn’t’ fit well with his previous dichotomies. Because the good kind of rotten, what we call fermentation, is as much cultural (prepared by humans) as it is natural (prepared by microbes).
The Good Rotten
Fermentation is the microbial modification of food for the better, with respect to human metabolism and general health. And notwithstanding Melville’s gag reflex, the fermented meat offered him by the Yakut was a good kind of rotten, without which the Yakut couldn’t survive
Many fermentative microbes prefer to operate without oxygen. In this way, fermentation is the opposite of cooking, which is a massively oxidative process. Some of the benefits are the same though. Like cooking, fermentation acts as a form of pre-digestion, thereby enabling the digestive system to extract energy from macronutrients (fats, proteins and carbohydrates) more efficiently. That buttery texture of the Yakut meat that Melville regifted was the result of pre-digestion through fermentation. During times of caloric stress, the Yakut dogs—and the working dogs of other northern peoples to this day—show a strong preference for fermented meat over fresh meat when under caloric stress.
But fermentation provides added value to raw foods above and beyond that provided by cooking. Melvilles’ meat illustrates one such added value—an extended “shelf-life”. Raw meat spoils quickly, cooked meat is more spoilage resistant but fermented meat doesn’t spoil for months or years. Melville’s meat may have been months old, but as his Yakut benefactors—and their dogs-- well knew, it was still perfectly safe to eat. Though the fermented meat would be considered rotten by Melville and his crew, it was rotten in a good way. Much rotten meat is rotten in a bad way, that is, a way that makes us sick and/or die. I will call food that is rotten in a bad way, spoiled. By “spoiled”, I mean toxic, not foods that are off-putting to those of European extraction. As Freegans (AKA dumpster divers) recognize, much of what we wastefully discard as spoiled is perfectly healthy fair, uncontaminated by pathogenic microbes.
Another important boon provided by fermentation is a plethora of prebiotics, probiotics, postbiotics, micronutrients and vitamins, that are not present in raw or cooked foods. Fermentation also removes toxins and anti-nutrients, which are part of the evolved defense systems of many plants. On the vitamin front, fermented meats provide an increase in B2 (riboflavin), B3 (niacin) B6, B9 (folic acid), B12, and K. Vitamin C also gets a major boost during plant fermentation.
Most mammals manufacture their own Vitamin C; we, unfortunately, can’t. Instead, we must rely on external sources, without which we suffer scurvy, manifest in open sores, bleeding gums and such. Vitamin C deficiency was a notorious problem for sailors on long voyages, from the 15th through the 19th centuries. The early solution was citrus juice. The term “Limey”, a derogatory term for members of the British Royal Navy, derives from the practice of adding a juice from the citrus they called lime—actually lemon—to the daily grog to ward off scurvy. Unfortunately, the juice itself gradually “goes off” with a consequent loss of vitamin “C”.
Howard Metzger discovered a better source of vitamin C in 1760--the fermented cabbage we call sauerkraut, which provides a more reliable source of the vitamin than citrus juice, because it lasts far longer. Captain Cook, aware of Metzger’s work, wisely chose to provision his ships with large volumes of sauerkraut for his extended Pacific expeditions. It had “the good quality not to loose any part of its efficacy by keeping, we used the last of it in September last, having been above two years on board and it was then as good as at the first” (original quote from Kodicek and Young 1969, reprinted in Speth 2017).
Cook had the most progressive ideas regarding health and hygiene among ship captains during the age of exploration. He lost only four of 100+ men in one three-year expedition, one of whom fell overboard. In contrast, 30 years earlier, Captain George Anson returned with only 20% of his original crew after a similar two-year expedition in the Pacific (Smith 2018). Sauerkraut was certainly a factor.
In a successful fermentation the good (fermentative) microbes outcompete the bad (spoiler) microbes. One way they outcompete spoiler microbes is by reducing the available oxygen on which many spoilers depend. Fermentative microbes have other cards to play as well. Most generally, the alcohols generated by some fermentations and the acids generated by others can’t be tolerated by the vast majority of microbes. Many good microbes also secrete selective bacterial toxins called bacteriocins that target particular microbial bad actors; others produce compounds that inhibit the bad fungi. These chemicals are already exploited in the food industry.
Though it is convenient to categorize fermentations as either alcoholic or acidic, most are a combination of both. Traditional breads, beers, koumiss, kefir and kombucha are examples of mixed fermentations. Even modern (red) wines, with their extremely streamlined microbiota, pre-packaged in a commercial laboratory, require mixed fermentations. Natural mixed fermentations result from the complex interactions of diverse actors in microbial ecosystems.
The degree to which a fermentation is acidic or alcoholic depends on the microbial actors that dominate. Alcoholic fermentations are dominated by single celled fungi called yeasts, of which the most well-known is Saccharomyces cerevisiae (Saccharomyces = sugar fungus; cerevisiae = beer, in Latin), commonly called the brewer’s (also baker’s) yeast. Acidic fermentations, on the other hand, are bacteria driven. Two of the most important groups of bacterial fermenters are lactic acid bacteria (LAB) and acetic acid bacteria (AAB). Molds (multicellular fungi) participate in both types of fermentation to varying degrees. Species of the Penicillin, Rhizopus and Aspergillus groups are particularly important fungal actors in fermented food today.
A number of species in the fermentative microbiota have been domesticated, as domesticated as dogs or wheat, more so if you consider the genetic alterations involved. In contrast to domesticated animals and plants, however, domesticated microbes are almost entirely self-domesticated through garden-variety natural selection. They took the initiative in exploiting the new food niches created by humans. It wasn’t until the last half of the 19th century that Pasteur discovered that yeasts and bacteria were the cause of fermentation, paving the way for “artificial selection”, which continues in ever more efficient ways to this day. The domestication of microbes probably began long before the domestication of plants and animals.
Domesticated microbes have diversified into many distinct genetic strains, much like dog breeds or grape cultivars. Many of these genetic strains have become specialized for very particular food niches in particular geographical and cultural environments. Later, we will explore the history of some of the more important microbe domestications. It will help to begin at the end, with a brief survey of the diversity of fermented foods available today. That will be the subject of the next post.