100 Million Years of Food (14 page)

The Burke and Wills debacle is usually portrayed as an example of cultural incompetence, since the explorers relied heavily on goods and technological might, while the Yandruwandha Aborigines were able to survive in the same area using the accumulated wisdom of their forebears. However, even the Aborigines used nardoo only as an emergency food. Consider the situation from the nardoo plants' point of view. Like a squatter squaring off with a bulldozer, if you put down roots in a patch of soil, intending to live there for the rest of your life, you'd put up a rocking good fight the moment anyone tried to browse on your limbs, prune your flowers, pull out your roots, or nibble on your immature seeds. Making the best of their immobility, plants discourage predation with an impressive battery of defensive compounds. A raised middle finger or a portrait of Che Guevara may be the conventional symbols of defiance to many, but a plant would be just as true to the spirit of resistance.

Apart from their fruits, plant parts are designed to be unpalatable through physical barriers or chemical warfare. We can group plants into six categories based on their effects when consumed:

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Enemies
: plants that should never be eaten. These include
assassins,
plants whose toxins we deliberately employ as means of carrying out murder, torture, or punishment.

•
Doppelgangers:
plants that poison us because we mistake them for palatable plants.

•
Sorcerers:
plants that we regularly use as medicines but that harm us when we accidentally overdose on them.

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Werewolves:
plants that are safe to eat at certain stages in their life cycles and dangerous at other life stages.

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Fallbacks:
plants that may be eaten as a temporary resort but are not suitable for long-term consumption.

•
Comrades
: plants that are suitable for long-term consumption when properly prepared.

Much of the confusion today over which plants to eat results from people indiscriminately lumping plants into the comrades category. However, just as in human relationships, not every plant that we meet is suitable as a long-term mate. Our ancestors were far more likely to place plants into the sorcerer or fallback category and instead regard animal foods as their true companions. People in traditional societies preferred to cook every vegetable, rather than eating them raw: Cooking is the best means of neutralizing plant defensive toxins in a diet that is largely based on vegetables, as well as unlocking edible calories in curmudgeonly plant tissues. White starch—from white rice, wheat flour, boiled potatoes, and so on—is highly valued (after meat, in any case) in traditional societies because in the long run, it is least likely to harm human eaters. Despite the gush of enthusiasm that nutritionists often profess for plant foods, citing antioxidants, vitamins A and E, fiber, polyunsaturated and monounsaturated fatty acids, potassium, or the absence of cholesterol and sodium in plants, the truth is that none of these properties have so far demonstrated conclusive benefit in well-nourished populations. What makes a particular food or cuisine healthy is whether or not it supplies the nutrients that our bodies evolved to require. Plant foods became an increasingly major force in our diets as our big animal prey dwindled around the world because people learned how to process, cook, and selectively breed the new plant foods.

Let us consider now a few examples of each of the plant categories, to reach a better understanding of the mysteries behind plant foods, and to illustrate that even common plants may have surprising properties.

ENEMIES AND ASSASSINS:
Some plants are plain poisonous but were employed anyway, as tools for punishment, murder, or suicide. A cruel punishment for Jamaican slaves was rubbing their mouths with the cut stalk of dieffenbachia (now a common houseplant), which caused painful swelling of the oral mucous membranes and rendered them unable to speak; hence its nickname of dumbcane. The extract was used as an ingredient in preparing arrow poisons by natives in the Amazon.
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Another example is the castor oil plant, planted as an ornamental. Castor oil is widely employed as a highly effective laxative, but the seeds contain ricin, one of the most potent poisons known. In 1978, the broadcaster Georgi Markov, a Bulgarian exile in London, was waiting for his bus to take him over the River Thames to his job at the BBC when he was bumped in the leg with an umbrella. The symptoms of his agonizing death, three days later, were consistent with assassination by ricin poisoning. The poison capsule that had tipped the umbrella and that had been injected under his skin was no larger than the head of a pin.
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DOPPELGANGERS:
Sometimes we eat noxious plants because of mistaken identity. The toxin from water hemlock, a plant sometimes confused with wild parsnip, wild carrot, wild celery, artichokes, sweet potatoes, or sweet anise, triggers spasms violent enough to make people bite through their tongues and smash apart their teeth.
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Another example of a doppelganger is meadow saffron, which may pass for onion; eating meadow saffron triggers thirst, diarrhea, stomach pain, delirium, and death in half of all cases. It may take up to three days for death to deliver merciful deliverance.
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SORCERERS:
Certain plants may be fatal to consume, but we attempt to employ them in small doses as medicines. Dieffenbachia, the houseplant mentioned above, was chewed by males in the Caribbean Islands to achieve temporary sterility lasting up to two days. Bitter melon, a fruit commonly found in Asia and in Asian grocery stores elsewhere, is anecdotally reported to improve symptoms of diabetes. In 2010, an Indian scientist reportedly died from drinking a particularly bitter concoction of bottle gourd and bitter gourd juice, a regimen that he had maintained for four years. His wife also drank the juice, but survived after vomiting blood and experiencing severe diarrhea.
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Bitter melon, cucumbers, and squashes concoct a bitter compound called cucurbitacin to protect themselves from insect and fungal attack. Although domesticated versions of these plants were bred to reduce their bitterness, when cucurbitacin is present in high concentrations, the bitter taste—gardeners are familiar with the bitterness of cucurbitacin in homegrown cucumbers near the stem end—normally compels people to stop eating before they become ill.

FALLBACKS:
Sometimes, poor people are forced to subsist on noxious plants out of hunger and poverty. Lathyrism, a disease that leads to back pain and paralysis of the lower limbs, results from prolonged diets of grass pea.
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Under conditions of poverty, famine, and interruption of agricultural work, people consume the hardy grass pea plant as a last-resort food item. Lathyrism debilitated thousands of people in northern India, and outbreaks occurred during hardships such as the Spanish Civil War (1936–39), among Romanian Jews confined to concentration camps, Greeks besieged by the Germans during World War II, and German inmates in France just after the close of World War II.
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Lathyrism may not just be a problem in Europe and Asia: Christopher McCandless, the young American itinerant whose life was recounted in the popular book and movie
Into the Wild,
may have died from lathyrism incurred by eating wild-potato seeds while attempting to live off the land in the Alaskan woods.
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WEREWOLVES:
Some plants are only troublesome at certain stages in their life cycles. In the fall of 1978, up to three hundred boys at a southeast London day school sat down for lunch, choosing from a menu of potatoes, steak pie, gravy, cabbage, tinned carrots, and dessert of apricot and syrup sponge pudding, with or without custard. By eight o'clock that evening, seventy-eight of the boys began to vomit and experience severe diarrhea and stomach pain. Seventeen boys were taken to the hospital; they developed fever, and their feces turned green. Three boys fell unconscious, and two spoke gibberish when they regained consciousness. Fortunately, by the eleventh day, all the boys had recovered enough to be discharged. The one food that all the stricken boys had eaten in common: potatoes. Domesticated potatoes have been bred to reduce the steroid alkaloid solanin to palatable levels, but tubers that are exposed to sunlight (thus making them vulnerable to being eaten) and turn green, or that have been attacked by disease or left to spoil, may produce dangerously high levels of solanin. Since solanin tastes exceptionally bitter, fatal poisoning by potatoes is uncommon, but it does occur, such as during the Korean War, when large segments of the North Korean population were reduced to subsisting on spoiled potatoes. Investigation into the London case suggested that the affected boys had consumed potatoes from an old bag that had been left over from the term prior to the summer.
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COMRADES:
Finally, we arrive at our plant BFFs (best friends forever), the vegetables, legumes, and cereals that we find in grocery stores, in our garden plots, and on our farms. These are the foods that most nutritionists recommend that we heap onto our dinner plates, lightly cooked or processed, if at all. Traditional societies certainly valued plant foods like these, but they were careful to process and cook them in ways that reduced their harmfulness. The chief benefit of our companion plant foods is that they do not poison us—not outright, anyway. Let us consider some of the defensive compounds that our everyday plant foods attempt to deploy on predators like ourselves.

Some defensive compounds cannot be reduced by cooking. For example, celery, parsley, and parsnip stock up on furanocoumarin, a compound that protects plants against insects but also can cause skin rashes in people who handle these plants (though eating celery does not present this problem). The skin rashes can be a hazard for field workers and are worsened when exposed to sunlight. Ironically, breeding for celery varieties that are more resistant to insects or fungi may inadvertently ramp up the concentration of furanocoumarins.
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Saponins, a defensive toxin deployed in chickpeas, soybeans, beans, peanuts, spinach, and asparagus (and also in sea cucumbers), are soaplike compounds that create a bitter taste and irritate mucous membranes. Saponins are toxic to cold-blooded animals such as insects and fish and are used around the world as fish poisons. Normally saponins cannot pass through the gut wall of humans. However, if for some reason saponins enter the bloodstream, such as through an injury to the gut, they can cause rupturing of the blood cells (hemolysis). Symptoms of saponin poisoning include dizziness, headaches, chills, irregular heartbeat, convulsions, and coma. Like furanocoumarins, saponins are fairly resistant to cooking or most other techniques of food processing, with the exception of fermented foods like tempeh (Indonesian fermented soybean), which have substantially reduced saponin content.
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Isoflavones, compounds that resemble and mimic the properties of estrogen, are produced by soybeans and to a lesser extent by other plants from the legume family, including alfalfa and clover. Animals that browse too much on isoflavone-rich plants, such as ewes feeding on clover, can become sterile, due to the disruptive hormonal effects of isoflavones. Soy-based formulas can interfere with steroid metabolism in infants. Like furanocoumarins and saponins, isoflavones are resistant to cooking.

In other cases, cooks in traditional societies learned how to make a good meal out of well-defended plants through ingenious food preparation techniques. Legumes (beans, soybeans, lentils, chickpeas, etc.) fortify their seeds with lectin compounds that cause gastrointestinal distress when consumed in large quantities, as well as growth reduction and liver damage.
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Protease inhibitors are a class of defensive compounds manufactured by legumes, cereal grains, and potatoes to prevent plant predators from being able to digest their foods. Hard-pressed peasants figured out that concentrations of lectins and protease inhibitors are reduced through food preparation methods such as sun-drying, pan-frying, deep-frying, roasting, soaking, boiling, and fermentation.
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Cassava is problematic due to cyanide compounds; populations in tropical countries that rely on cassava as a staple may suffer from cyanide poisoning, goiter, or neurodegeneration. Traditional methods of making cassava safer to eat include sun-drying, soaking, grating, and roasting. Lima beans, sorghum, and bamboo may also induce cyanide intoxication. Clever tricks to reduce cyanide content include grating, chopping into smaller pieces, drying, boiling, prolonged submersion in warm or hot water, steaming, roasting, and fermentation.
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(Boiling should be done uncovered, to allow cyanide gases to escape completely.)
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There are also plant parts that are not built specifically for defensive purposes but can still damage the health of predators. Like an attractive best friend who mesmerizes your potential dates, phytates are storage forms of phosphorous that bind to minerals and therefore have the tendency to deplete our bodies of essential minerals such as calcium, magnesium, zinc, and iron. Soybeans, beans, cashews, sesame seeds, pistachios, chickpeas, peas, apples, eggplants, tomatoes, and papayas contain phytates. Oxalates, which may also steal your calcium and other minerals and are a risk factor in developing kidney stones, are abundant in spinach, okra, chocolate, couscous, whole-meal rye, whole-wheat bread, durum wheat, and especially wheat bran. Dehulling, soaking, cooking, and sprouting are common food preparation methods that reduce phytate content, while oxalate levels in foods are reduced by dehulling, boiling, steaming, baking, breadmaking, and fermentation.
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In other words, our relationships with our plant food comrades, even those that have been with us for a long time, require a lot of work to maintain on good terms.