Feature

Omnivore's Dilemma

New foods terrify and attract us -- are genetically modified foods following the same route as potatoes and tomatoes?

Jay Donald Mann

The current public hysteria about genetically modified foods should have been predicted, arising as it does from the overwhelmingly powerful urges of humanity's biological ancestry. What has been called "the omnivore's dilemma" is that new foods both terrify and attract us. Our ancient instincts tell us that a new food might be poisonous, yet adding improved or cheaper foods to our diet might give us the chance to snatch an advantage over our competitors. These considerations are not subject to logical analysis and reason.

As Eaton put it, we have had 100,000 generations as hunter-gatherers, 500 generations dependent on agriculture, 10 generations of the industrial age, and only two generations of fast foods. Our genes are those of omnivorous hunter gatherers. We fear newness, we are "neophobic".

The power of such instincts is evident in the rat, an omnivore nearly as successful as humankind. No matter how hungry it may be, a starving rat nibbles but a small taste of a new food. If the rat feels unwell during the next day, it will reject that food forever. Otherwise, the new food goes on the approved-for-rodents list.

Are we any different from rats? How many foods do you or your friends no longer eat because on a single occasion you became ill afterwards? It doesn't seem to matter whether you realise that the illness was caused by something else entirely, such as the onset of an infectious disease or seasickness. A single bad experience puts us off a food for years, if not for the rest of our lives.

We can examine food neophobia by stepping back into history. When the Spanish and Portuguese occupied the Americas, they sent many new crops, such as peppers, potatoes, tomatoes and maize back to Europe. These new crops were the genetically modified foods of the 16th and 17th Centuries. Public response to them was every bit as intense and instinctive as today's media-whipped hysteria. In a so-called Age of Rationalism, marked by the writings of Thomas Jefferson and by the French Revolution, it took about two centuries for the public to accept the new foods. Is there a lesson for our own time?

Potatoes: Fit for Pigs

Potatoes, brought from Peru to Spain by Pizarro, were enthusiastically sold in Europe at high prices, not as a food, but as an aphrodisiac. Potatoes reached Ireland in 1565. They became popular not only because they grew so well, but also because they could be left hidden in the ground while the landlord's agent confiscated harvested crops. In a week, a typical Irish family with four children ate 100 kg of potatoes, 16 kg of oatmeal, a little milk and an occasional salt herring. Some ascribed the fecundity of Irish families to the effect of potatoes; Nietsche wrote with Teutonic logic, "a diet that consists predominantly of rice leads to the use of opium, just as a diet which consists predominantly of potatoes leads to the use of liquor".

In the Netherlands, potatoes became a valued item of the diet. The Dutch served them to Peter the Great, who brought them back to Russia, where his ungrateful peasants called them "the Devil's apples". The Dutch also brought potatoes to Japan, where they were relegated to stock feed for centuries.

Potatoes were rejected as food in most of Europe because they were thought to carry leprosy, the scabby misshapen tubers being linked by sympathetic magic with the hands and feet of lepers. As a public health measure against the spread of leprosy, a French parlement of 1748 forbade the growing of potatoes, thus achieving the world's first Potato-Free Zone.

Although the dislike of potatoes was probably based on their scabby appearance, it was rationalised in many ways. Some people refused to eat anything not mentioned in the Bible. Even though they were not accepted as food, potatoes were considered as a natural remedy good for gout, lumbago, rheumatism, sore throat, sunburn, frostbite, drunkenness, black eyes, temper tantrums, sprains, sciatica, warts, toothaches and equine thrush.

Potatoes were sent to Thomas Jefferson's innovative Virginia farm from Ireland. The crop was no better trusted in North America than in Europe. During a bleak time in the Revolutionary War, John Adams wrote to his wife Abigail, "Let us eat potatoes and drink water rather than submit". Potatoes were relegated to livestock feed until the late 1800s. People who ate them as vegetables were told that they risked rickets, scrofula, leprosy and syphilis. One preacher accused the vegetable of leading to wantonness.

In Germany too, potatoes were almost exclusively fed to animals, and farm handbooks recommended planting them close to the pig pen. Food suitable only for pigs was deemed appropriate to feed French prisoners during the Seven Years War. Antoine-Auguste Parmentier, a captured army pharmacist, came to appreciate this so-called pig food. After peace was declared, in 1763, he devoted his energies to propagandising the despised potato as a food for French consumption. At first, he did not get very far in promoting what was still an illegal crop, even though he won a prize for an essay on how to alleviate public hunger.

In 1769, a parish priest who offered his starving Parisian flock a potato soup disguised it as "economy rice soup". During the next decade, the French upper class began to appreciate the possibilities of potatoes to feed the poor, but the illiterate peasants remained unconvinced. Eventually Louis XVI and Marie Antoinette grew 50 acres of potatoes on an erstwhile parade ground in Neuilly. Shrewdly, the monarch set an ostentatious guard of soldiers with fixed bayonets to protect this valuable crop. At night, the guard was intentionally relaxed, allowing the public to poach the royal potatoes. Think what history would have been like if Marie Antoinette had had the nous to remark, "Let them eat potatoes".

Although the first potato recipe book appeared in Germany in 1581, it wasn't until a disastrous failure of other crops two centuries later that potatoes were seriously contemplated for human dinner plates. One landmark in this change of attitude was the "Brandenburg Potato Paper" of 1770 issued by Emperor Frederic Wilhelm, who ordered peasants to plant potatoes or else have their noses and ears cut off. Despite this Imperial edict, the wagonload of potatoes sent in 1774 by Frederick the Great to the hungry citizens of Kolberg remained uneaten. In response, Frederick the Great appeared on the balcony of the Imperial Palace in a public consumption of potatoes.

Once the potato phobia had been broken by the combination of hunger and official pressure, there was no holding back. Less than ten years later, the War of Bavarian Succession (1778-1779) was popularly called the "Potato War" because the two armies spent most of their time destroying the other side's potato fields.

As late as 1875, the potato was still encountering heavy going in Bavaria, where the Englishman, Benjamin Thompson (later Count Rumford), had devised a nutritious potato-and-barley soup to feed the Bavarian army. The Bavarians so mistrusted potatoes that this key ingredient of Rumford's mystery soup was secretly prepared in a high-security area of the kitchen by selected chefs.

In 1800, starving Italians rejected a relief shipment of Irish potatoes. In 1840, an attempt by the Russian government to introduce potatoes was met by peasant riots in ten provinces. (In that same year, starving Irish rejected a relief shipment of imported maize. There were no horror stories about maize but it was simply new food to the Irish, and hence not to be trusted.)

When we look at German and Russian diets today, it's difficult to imagine that it took more than two centuries for their populations to accept potatoes. It is also noteworthy that acceptance of potatoes in one country did not seem to influence their acceptance in other nations. The history of potatoes in England seems to be one of relatively facile acceptance by the population, whilst being shunned by the royal family. When first introduced, the palace chefs thought the lumpy tubers too unsightly to serve to royalty. Instead, they prepared a dish with boiled potato leaves and sprouts! As might be expected, everyone at Buckingham Palace became ill. It took about two centuries before potatoes returned to the royal menu.

Tomatoes: Look, Don't Eat!

The history of tomatoes is even more colourful. Although the Peruvians appreciated them as tasty additions to the diet, in Spain and particularly Morocco, they were grown almost purely as ornamentals. Hence the Italians called the fruits pomo dei mori, the apple of the Moors. In an early masterpiece of spin-doctoring, the name was changed to pomme d'amore, or apple of Love. Indeed, tomatoes were regarded in Europe as a sensationally effective aphrodisiac. Gerard wrote "We only have them for curiosity in our gardens, and for the amorous aspect or beauty of the fruit." They joined a noted list of love-linked plants that included artichokes, sea holly, chocolate, carrots, broad beans and candied orchid roots. (Every single new food seems at first to be regarded as an effective aphrodisiac. Hope springs eternal in the masculine breast. Effects elsewhere in the male anatomy are dubious, however.) Tomatoes were popularly called the "wolf peach", suggesting the poisoned meat that was thrown out to destroy wolves. The official botanical name for tomato, Lycopersicon, immortalises this belief.

Only in Italy were tomatoes accepted. As early as the late 1500s, cooked tomatoes with olive oil, salt and pepper were part of the Italian diet. An oil was pressed from tomato seeds, and used to make a kind of soup. Raw tomatoes were still treated with suspicion, and were not consumed in England until the 19th Century.

In North America, the indefatigable Tom Jefferson tested tomatoes on his Virginia farm by 1781. Twenty years later, an Italian immigrant failed to get anyone in Massachusetts even to taste them. Perhaps because of the apple-of-love sobriquet, the fruits were condemned by ministers and physicians. Pilgrims considered them to be on a par with dancing, card-playing and theatre-going. One pastor was defrocked because he grew tomatoes, as an ornamental, in his garden.

A historical moment that should be commemorated by tomato lovers was the 26th of September, 1820. On that date an eccentric gentleman, Colonel Robert Gibbon Johnson, mounted the courthouse steps of Salem, New Jersey, announcing that he would publicly eat an entire basketful of tomatoes. The local physician predicted that his patient would "foam and froth at the mouth and double over with appendicitis". Others predicted high blood pressure and brain fever. It was widely thought that tomato skins would stick to the lining of the stomach and eventually cause cancer. (That belief persisted for decades.) While the intrepid Colonel munched his way through the fruit, he was serenaded by the local firemen's' band playing dirges. To the amazement of all, Colonel Johnson survived, and lived to the age of 79. By 1828, tomatoes were being pushed as cure-all nostrums such as Dr Mile's Compound Extract of Tomato, and Dr Phelps' Compound Tomato Pills.

What have we learnt?

As these historical anecdotes show, any new food is instinctively regarded as potentially poisonous. What is "new"? To most biologists and plant breeders, genetically modified (or genetically engineered) crops are just a continuation of 5,000 years of human intervention into the heredity of plants. They know that the food value and risk of consuming the modified crops isn't changed. Indeed, the more precise ways to alter crops are probably less risky than conventional breeding methods, which willy-nilly transfer an unknown handful of genes. The general public, though, doesn't yet regard DNA vectors, antisense codons and the like as being a simple extension of what has gone before.

Contradictions abound. Triticale, which is so widely used in multigrain bread, is a totally artificial cross between wheat and rye, The hodgepodge of tritricale genes somehow is "safe", whereas a single well-understood "outside" gene is somehow "unsafe".

In one important feature, we humans are worse off than a starving rat in a candy store. The rat can recognise which candies it has tried before, and which are new. Because GMO crop products are generally indistinguishable at marketplace level, there is no obvious way to distinguish new from old. This is neither an accident nor a conspiracy. Most of the genetic modifications so far have been those that simplify crop growing, reducing the need to use persistent herbicides or insecticides. None of these characteristics gets through into isolated oils or seed proteins, but we mistrust them nevertheless.

How much of the opposition to genetically modified foods is instinctive? It's interesting how many different objections have been made against these foods. In a single page of one magazine I found: "the essentially unlimited health risks", "many harmful and fatal effects including cancer of the organism", "infectious neurological disease", "highly virulent new viruses", "disruption of the genetic blueprint of the organism with totally unpredictable consequences", "unexpected production of toxic substances", "a greater threat to the world than the advent of nuclear technology", and "an irreversible attack on the biosphere".

Why are so many different possibilities needed to rationalise opposition to GMO? Is it possible that the opposition came first, and the justification(s) were dredged up later? Could GMO food be so obviously obnoxious, yet pass all the overseas testing even in the US, the most litigious nation on earth?

Some people are allergic to eggs. Chocolate gives me cold sores and gives others migraine headaches. We don't need a lengthy lists of possible evils supposedly caused by eggs or chocolate. A single factual reason is all that's needed to explain our avoidance of these foods.

Some of the positions taken by opponents of genetically modified foods seem at variance with their previous positions. Many have objected to broadcast spraying with wide-spectrum insecticides. Therefore, a crop plant with an internal insecticide, harmless to mammals and to beneficial insects, toxic only to insects that try to eat the crop, should have been welcomed.

Similar considerations apply to weed control. One of the greatest advances in crop breeding came with the realisation that most crops grew too high to suppress weed growth. Shorter crops, less likely to topple over, can put more of themselves into the seeds or fruits that we want. The farmer's job is to keep down the weeds by other means, whether it be by hand-hoeing, fuel-consuming mechanical or flame cultivation, or by spraying with herbicides.

The advantage of glyphosate (Roundup) is that it is nonpersistent, is rapidly inactivated in contact with soil, and is non-toxic to animals. Roundup blocks plant synthesis of an amino acid. We animals don't make this amino acid anyhow, and get it from our diet. Roundup-ready plants make that amino acid in another way, so they are not deficient in this nutrient. One might have expected so-called environmentalists to welcome the replacement of more persistent herbicides with Roundup, rather than to condemn it.

Changing Instinct into Reason

If genetically modified foods are safe, how can we overcome our instinctive mistrust of them? How important was it that historically potatoes and tomatoes were generally accepted only after they were publicly consumed without harm? If my hypothesis is right, we probably must go through the rat-style approach of cautiously tasting a GMO food product for ourselves. We can wait for a day or so, and see if there's any adverse reaction.

For this self-testing to be possible, therefore, it is not sufficient merely to use "may contain GMO components" labels. Instead, a courageous manufacturer needs to proudly proclaim the use of GMO ingredients. A useful product label will explain the advantages of the technology (eg., allowing use of an animal-safe, non-polluting herbicide) and, if appropriate, explain that the oil or protein isolate does not contain any DNA whatsoever. That will allow the consumer to taste-and-see.

Limited experience suggests that such an honest approach can pay off. Radiation-treated strawberries in the US were test marketed with clear labels indicating that they had been treated but were not themselves radioactive. Because such strawberries keep much better, they sold at a premium price to a large proportion of grocery shoppers.

Genetically modified foods should, at this stage, be cheaper, with more efficient production involving fewer sprays. In the future, however, many modified foods will be superior to conventional versions. For how many years will the New Zealand public deprive itself of them?

Testing out strange new foods has always been a tricky business, but it's one which humanity has faced many, many times.

Suggestions for further reading:

Challem J, "The paleolithic diet". Nutrition Science News, April 1997, in www.nutritionsciencenews.com/NSN_backs/Apr_97/paleolithic.html

Leeming, Margaret. A History of Food. BBC Books (London) 1991.

Rupp, Rebecca. Blue Corn & Square Tomatoes: Unusual facts about common garden vegetables. Storey Communications Inc (Pownal, Vermont), 1987

Smith, Bruce D. The emergence of Agriculture. Scientific American Library (W H Freeman, NY) 1998.

Tannahill, Reay. Food in History. Crown Trade Paperbacks (Random House, Auckland) 1989.

Toussaint-Samat., Maguelonne. History of Food. Blackwell (Oxford), 1993

Dr Jay Mann is a plant biochemist.