Tasty (14 page)

Modern sugar substitutes such as saccharin, the active ingredient in the pink packets of Sweet'N Low, and aspartame, used in diet soda, have their own problems. They don't taste like sugar. Table sugar, made from sugarcane or sugar beets, is made of sucrose, a molecule in turn made of two sugars, fructose and glucose. High-fructose corn syrup is a physical mixture of those two, with slightly more fructose. Of all the sugars, fructose is the sweetest. The uncannily precise bond between sweet receptor and fructose molecule means there is no other substance capable of exactly mimicking its taste.

The molecules of substitutes bond to sweet receptors, but don't fit perfectly, like a key that slides into a lock but
won't turn all the way. They also bond to other types of receptors, including those for pungency and bitterness. The result is odd, off flavors, such as aspartame's faint metallic aftertaste, that don't fully ignite the brain's pleasure circuitry. Most sugar alternatives don't dissolve well in water, either, and will cling to the tongue rather than remain in solution. This means they pack a sensory punch—aspartame is about two hundred times as sweet as table sugar—but it can also make their tastes linger too long. The differences in chemical structure also make them poor baking ingredients. Sugar is not just sweet but versatile. Heat it and complex flavors emerge, with hints of acidity and bitterness. It can take multiple forms and consistencies, from crystals to caramels, that no substitute can touch.

Today's dominant artificial sweeteners are also lab-­engineered industrial chemicals. Saccharin is a coal-tar derivative accidentally discovered at Johns Hopkins University in 1878. Aspartame was found in 1965 when a lab scientist at the pharmaceutical company Searle absentmindedly licked his index finger, which was dusted with an ingredient from an ulcer drug. Sucralose, the active ingredient in Splenda, was found while researchers for the sugar giant Tate & Lyle were studying ways to turn sucrose derivatives into an insecticide. The health concerns over sweeteners are more ambiguous than those surrounding sugar. Aspartame produces trace amounts of methanol in the intestine, a form of alcohol the body transforms into ­formaldehyde—the chemical used in embalming fluid, and a ­carcinogen—before it breaks down again. But so do oranges and tomatoes. The Food and Drug Administration banned saccharin in 1976 because of a tentative link to cancer in lab animals, but
later unbanned it because the evidence was scant. Sucralose is not broken down in the body. However, recent studies ominously show that artificial sweeteners may contribute to diabetes.

Shell-shocked consumers are rejecting artificial ingredients on general principle. In 2013 alone, sales of Diet Coke and Diet Pepsi each plunged by 7 percent. Since the early 2000s, food and soft-drink makers have spent tens of millions of dollars in a race to find natural sugar substitutes. Many plants produce sweetish substances. But these don't taste exactly like sugar either. Thaumatin, a protein found in
Thaumatococcus daniellii
, a plant that grows in West African rain forests, is the sweetest substance known—three thousand times more potent than sugar. It lingers on the tongue for minutes, leaving licoricey aftertastes. Stevia, made from the leaves of the South American
Stevia rebaudiana
plant, has a bitter edge.

Homaro Cantu believed the frustrations of big food companies offered an opening for miracle berries, though he faced his own set of obstacles. In 1974, the FDA had classified miraculin as a food additive, meaning it would have to go through extensive testing before it could gain approval as an ingredient. Its advocates claimed that the US sugar industry, which wields substantial clout in Washington, had lobbied for this behind the scenes. Miraculin is currently classified as a dietary supplement. By the time Cantu found it, several startups had sprung up to market and sell miracle berry extracts. The
price
wa
s still high—a single pill cost $1.50—but researchers had found ways to transfer miracle berry genes to tomatoes and lettuce, which can produce much larger amounts of miraculin than berries. Chemically,
miraculin is not even a sweetener. Its flavor is mild. Instead, it alters other flavors, sometimes unpredictably. This may not be enough to start a diet revolution. But it does show that there are new frontiers of sweetness that have yet to be fully explored.

CHAPTER 6

Gusto and Disgust

A
s HMS
Beagle
sailed along the South American coast toward Tierra del Fuego in 1833, Charles Darwin had a series of scientific adventures. He had been recruited by the
Beagle
's captain, Robert FitzRoy, as a geologist to aid the ship's principal mission, mapping the South American coastline and seafloor. In a few months, they would reach the Galápagos Islands, off the coast of Peru, where Darwin would find the strange flora and fauna on which he would base his theory of evolution. As the
Beagle
sailed south, he spent most of his time on land, observing and collecting geological specimens. At Bahía Blanca, Argentina, he rode with gauchos into the pampas and dined with them on roast armadillo. In Uruguay, he bought the skull of an extinct rodent, the size of a hippo's, from a farmer for eighteen pence. At Punta Alta, on the coast of Patagonia, he found bones from a megatherium, a huge, extinct armored sloth.

Darwin was both fascinated and repelled by the indigenous people living at the southernmost tip of the continent. He was twenty-three, on his first voyage, and had plunged into an alien world full of strange sensations. The people he met were the strangest of all. The Yahgan tribe lived a marginal existence as hunter-gatherers, roaming the archipel
ago near Cape Horn in dugout canoes. Most had long hair and wore little clothing, even in frigid weather. When the
Beagle
rounded the cape, he observed some of them rowing canoes. They struck Darwin as strange and degraded examples of humanity. “These poor wretches were stunted in their growth, their hideous faces bedaubed with white paint, their skins filthy and greasy, their hair entangled, their voices discordant, and their gestures violent. Viewing such men, one can hardly make one's self believe that they are fellow-­creatures, and inhabitants of the same world.”

Their food was vile. “If a seal is killed, or the floating carcass of a putrid whale is discovered, it is a feast; and such miserable food is assisted by a few tasteless berries and fungi,” he wrote in his journal. The Yahgan would render the carcasses of beached whales, burying their meat and blubber in the sand. Without oxygen, it would ferment rather than decay. A few months later they would unearth it and feast. A shipmate who had spent time in the region filled Darwin in on the worst of it: cannibalism. When famine struck, the Yahgan ate their old women before their dogs. A native boy had explained the rationale: “Doggies catch otters, old women no.” The unfortunate grandmas would sometimes escape into the mountains, then be captured and brought back to the hearth, where they were suffocated with smoke, then butchered for the choicest parts. (This was almost certainly a rumor; anthropologists have found no evidence that the Yahgan practiced cannibalism.)

On January 19, 1834, the ship anchored at the midpoint of the Beagle Channel (so named after the same ship explored it six years earlier), a one-hundred-mile stretch of water north of Cape Horn. A party of twenty-eight disembarked, including FitzRoy, Darwin, and three Yahgan, who had been cap
tured on a previous voyage and were returning home after three years in England. They took four boats and rowed along the eastern bank. The following day, they entered an inhabited area; surprised Indians lit signal fires up and down the shore, and some followed the boats. The
Beagle
party came ashore near a Yahgan camp, and a tentative meeting took place. Initially hostile, the Indians warmed as the crew handed out gimlets (small tools for boring holes) and stretches of red ribbon that they tied around their heads. One of the three returning Indians, Jemmy Button, “was thoroughly ashamed of his countrymen, and declared his own tribe were quite different,” Darwin wrote, “in which he was woefully mistaken.”

As they all sat around campfires, Darwin opened a tin of preserved beef and began to eat. Canning had been invented only twenty years earlier, and canned meat had only recently become standard shipboard fare in the British Empire. Its taste was passable at best, something like the canned corned beef sold today, but a vast improvement over the smoked and salted meats in use a decade earlier, which rotted on journeys of any length.

“They liked our biscuit,” Darwin wrote. “But one of the savages touched with his finger some of the meat preserved in tin cases which I was eating, and feeling it soft and cold, showed as much disgust at it, as I should have done at putrid blubber.”

The next day, the party rowed to Wulaia Cove, where they left their “civilized” Yahgan companions, and continued to explore the area before returning to the ship a week later.

But the meat-tin incident stuck in Darwin's head. His observations of the Yahgan forced him to confront his prejudices. Unlike many educated Europeans of the time, he believed that the absence of civilization, not a savage nature, was responsible for the natives' bizarre tastes and abject cir
cumstances. If this were true, the extremes he observed meant human behavior and sensibilities were even more malleable than he had imagined.

Almost forty years later, after
On the Origin of Species
had secured his place in history, Darwin wrote about this encounter in his new book,
The Expression of the Emotions in Man and Animals.
The book's main argument was a controversial, though logical, extension of his theory of natural selection: mankind's infinitely subtle emotional expressions, thought to be reflections of the soul, had evolved from those of ­animals. Both the Yahgan man's and his own reaction to the meat tin exemplified disgust, an emotion that had originated as a response to noxious foods but had evolved into something more complicated:

The term “disgust,” in its simplest sense, means something offensive to the taste. It is curious how readily this feeling is excited by anything unusual in the appearance, odour, or nature of our food. In Tierra del Fuego a native touched with his finger some cold preserved meat which I was eating at our bivouac, and plainly showed utter disgust at its softness; whilst I felt utter disgust at my food being touched by a naked savage, though his hands did not appear dirty.

Each man had been repelled not by the meat's taste or smell but by some ephemeral quality springing from a mixture of the sense of touch and imagination. For the Yahgan tribesman, it was the feel of this strange new food on his fingertip and the thought of it on his tongue. For Darwin, it was the idea of eating something touched by such a degraded example of humanity, who had, perhaps, consumed human flesh.

The word “disgust” comes from the Latin verb
gustare
, to taste and to enjoy; and the prefix
dis
, meaning “apart” or “not.” It is literally deliciousness negated. Disgust is a uniquely human reaction based on ancient taste aversions to bitterness, sourness, and excess salt, eventually broadened to include noxious smells. But disgust is elastic. Darwin described it as “something revolting, primarily in relation to the sense of taste, as actually perceived or vividly imagined; and secondarily to anything which causes a similar feeling, through the sense of smell, touch, and even of eyesight.” Almost anything, it seems, can provoke it: a touch, the sight of a sick person, gore, violence, a personal betrayal, sexual deviance, and classes of people. What do the senses of taste and smell have to do with this assortment of seemingly unrelated responses?

Basic tastes stir desires and gratification. Aromas summon memories and feelings. The brain effortlessly assembles these into sensations. Flavor is all in your head, a wholly internal experience. But
Homo sapiens
is an innately gregarious species that evolved living in groups, eating together, and cooperating to ward off danger. Human senses engage with the world—and other humans. Disgust is, in other words, a medium of communication. Its distinctive grimace is present from birth. “I never saw disgust more plainly expressed than on the face of one of my infants at the age of five months, when, for the first time, some cold water, and again a month afterwards, when a piece of ripe cherry was put into his mouth,” Darwin wrote. “This was shown by the lips and whole mouth assuming a shape which allowed the contents to run or fall quickly out; the tongue being likewise protruded. These movements were accompanied by a little shudder.” This is more than just a particular arrangement of facial muscles. It is a mediation between a person's own pri
vate universe of sensation and the life of the group, which lives or dies depending on its skill for communicating feelings and information.

• • •

Darwin researched faces with verve and invention. He asked scientists and missionaries around the world to gather evidence on the emotional responses of aboriginal peoples. He asked the young mothers he knew for anecdotes about the faces their children made. He collected friends' observations of their dogs. He commissioned or collected dozens of drawings and photos. This presented obstacles. Facial expressions, like the feelings they express, are fleeting, and photography techniques of that era required long exposure times. A subject would have to remain perfectly still, face frozen, for a minute or longer. Instead, Darwin obtained photos from the experiments of a French doctor, who had administered electricity to a patient who had lost all feeling in his face. This produced fixed expressions for as long as necessary, though the images had an unsettling appearance.

Emotions
was wrong on some points. It argued a later-­discredited concept that animals could inherit new facial expressions that their parents had learned. But over the past forty years, science has since shown that one of the book's basic insights was correct: facial expressions have biological and evolutionary roots.

In the late 1960s, the psychologist Paul Ekman visited members of the remote Fore tribe in the highlands of southeast New Guinea. He was testing an idea central to Darwin's book: because human facial expressions had evolved from those of animals, they transcended culture and conditioning and could be recognized anywhere on earth. Margaret Mead,
the influential anthropologist, argued that culture was the force that molded human emotions and actions. A generation after World War II, suggesting human behavior was driven by biology or genetics was sometimes compared to eugenics, even Nazism. Darwin's book had been out of print for decades and almost forgotten, and its ideas had fallen into disrepute.

Darwin theorized there were six universal facial expressions, articulating happiness, sadness, anger, fear, surprise, and disgust. He believed that disgust, and perhaps happiness, were tied to food and flavor. Ekman had a million-dollar grant from the Defense Department to study facial expressions. He began his research with isolated Stone Age tribes. If their affects matched those of people in modern societies, that would demonstrate that the influence of culture had been overrated, and that there was something more elemental at work.

The Fore had already attracted scientific attention because they practiced ritual cannibalism, eating the brains of their dead. In the early 1960s this led to an epidemic of kuru, a disease that destroys brain tissue, producing tremors, seizures, dementia, and, ultimately, death. Both kuru and mad cow disease are caused by misfolded proteins called prions in brain tissue. By chance, Ekman found films of the Fore that National Institutes of Health researchers had made while studying the kuru epidemic.

Ekman spent months studying the faces in the movies. He observed how the Fore reacted to bad food, to pain, and to each other. “I found that Darwin was right,” he said. “Because every expression you'd ever seen was in that culture. But the question was, how do you get scientific proof of this?”

He traveled the world, testing the reactions of college-age people in the United States, Japan, Brazil, Argentina, and
Chile. He found they could consistently identify the same basic expressions. But when he tested members of the Fore and one other tribe, the Sadong of Borneo, he found that their interpretation of some expressions did not match those of the college students. He wondered if his observations from the films had been off. But other factors might also be influencing the results. Working with Stone Age tribes had posed unusual obstacles. The tests required volunteers to read basic instructions and a list of emotions while responding to photographs of faces. But the Fore couldn't read, so a tester had to read instructions to them. It was also hard to translate words for specific emotions into their language. Ekman could also not be sure that the Fore hadn't picked up knowledge from the outside world that influenced their answers. Ultimately, he redid the tests with a twist. He recruited children who had had minimal contact with missionaries and other outsiders. Instead of a list of emotions, he used a set of very brief “stories” keyed to Fore culture, each of which captured a particular emotion. The story for disgust was “He/she is looking at something he/she dislikes,” or “He/she is looking at something which smells bad.”

These tests showed the Fore's facial expressions were nearly identical to those of people in developed countries like America or Japan. There were subtle differences, suggesting that cultural forces play a role in shaping these reactions: the Fore did not make the same distinctions between fear and surprise that other cultures did. While the Fore recognized disgust when they saw it in others, the things they found disgusting varied. But it appeared Darwin had been correct on another point as well: fundamentally, the differences between citizens of the British Empire and the inhabitants of Tierra del Fuego were not so vast after all.

•••

The basic version of the “yuck” face sends a clear and highly useful alarm to others:
Spit that out!
Seeing it produces an empathetic wince. This form of messaging is indeed a legacy of human evolution. A lot of our formidable brainpower is devoted to making and understanding facial expressions. Humans, apes, and some monkeys have much larger primary visual cortices—the brain's initial processing area for sight—and larger knots of neurons devoted to the control of facial muscles than other mammals. These species live in larger groups than other primates do, with more complex social hierarchies. For early
Homo sapiens
groups, the rhythms of hunting, gathering, and preparing food, and then sharing and savoring it, would have encouraged ever more subtle and precise forms of communication. At some point, the spit-that-out wince of disgust, which many mammals display, began to serve new purposes. The most important of these was a warning against disease.