In 1798 the English economist and cleric Thomas Malthus laid out what he called the immutable laws of human existence: “First, That food is necessary to the existence of man. Secondly, That the passion between the sexes is necessary and will remain nearly in its present state.”

Passion, in Malthus’s time, led inexorably to children (he had no inkling of birth control), and thus to a population that, when unchecked by famine, disease, or war, increased in what Malthus called a “geometrical ratio.” Assuming that each married couple would have 4 children and that all of them would marry, 2 would become 4 would become 8 would become 16 would become 32 would become 64. The “power in the earth” to produce the necessary food for those people, however, Malthus reasoned, can at best increase in what he called an “arithmetical ratio” over the same time span: 1, 2, 3, 4, 5…. Following this reasoning, Malthus argued that in a couple of centuries there would be 512 times as many people, but only 10 times as much food.

Even if “by breaking up more land and by great encouragements to agriculture” every acre in Britain were to be made into a garden, Malthus concluded, the country would not, within 50 years, be able to feed its people.

Malthus was extremely influential. Charles Darwin’s principle of natural selection, for instance, was a result of his reading Malthus’s Essay on the Principle of Population. At the same time, Malthus acquired a reputation for being hardhearted. He blamed the declining quality of life in Britain on the irresponsibility of the lower classes—they simply had too many children. He believed that government aid encouraged them to have more children than they could support. He thought that only those who worked should eat. A Malthusian worldview remains synonymous with the gloomy belief that only famine, disease, and war can control population and solve the world’s food problems.

But birth control was not the only concept Malthus’s essay did not take into account. On the cusp of the nineteenth century, several scientists were struck by the idea of increasing what Malthus called the “power in the earth” to produce food. They began to look at agriculture scientifically. The German botanist Julius von Sachs was one of this group. An expert on the tiny hairs on a plant’s roots, Sachs invented several devices to quantify how those hairs took up water and nutrients. The secret to his “artificial plants,” grown in water, freed of soil, was knowing what to put in the water: that is, understanding the chemistry of plant life.

Ever since 1772, when English chemist Joseph Priestley grew mint inside a sealed jar and observed that even months later the air within would “neither extinguish a candle, nor was it at all inconvenient to a mouse,” scientists had known that plants give off oxygen. That the same process, photosynthesis, also provides the carbon of which plants are mostly made was suggested in 1779 and proved “with classical completeness,” says Sachs, in 1804. In that year Theodore de Saussure showed that in the presence of sunlight the green parts of plants take in carbon dioxide and water and turn them into sugar and other carbohydrates, giving off oxygen.

Yet, Sachs notes, “For 40 years subsequently, almost inconceivable misapprehensions again obscured the clearly established fact” that

plants literally make food out of thin air. The carbon and other elements in plants, people argued, must be different from the elements in rocks and air. In living things, they thought, the elements must contain a vital force. In 1828 German chemist Friedrich Wöhler believed he had disproved the vitalist notion when he synthesized urea, considered vital because it was excreted by animals. “I must tell you,” he wrote to a friend, “that I can make urea without the use of kidneys either man or dog. Ammonium cyanate is urea.” And nitrogen, therefore, was nitrogen.

Still, it was not until the 1840s, when Wöhler’s friend and colleague Justus von Liebig published his Organic Chemistry and Its Applications in Agriculture and Physiology, that these advances in plant science began to affect farming. Liebig’s book, which focused on soil fertility, sold thousands of copies in America alone, while his letters to agricultural magazines reached many more farmers worldwide. When the Civil War began in 1861 Liebig was far better known around the world than Abraham Lincoln.

The first application of agricultural science was fertilizer. Before 1842 English farmers spread on their fields saltpeter from India, nitrate of soda from Chile, guano from Peru, slag (a waste product from the iron foundries), gypsum, lime rocks, and bones. Bones and lime rocks contain the phosphate plants need, but they are still poor fertilizers: their calcium phosphate dissolves poorly in water and so is hard for a plant to absorb. James Murray, an Irish doctor with a calling toward chemistry, found that acid converts calcium phosphate into calcium hydrogen phosphate and calcium dihydrogen phosphate, both of which dissolve readily. Murray mixed a paste of acid-treated bones or rocks with sawdust and bark to produce a slow-release fertilizer. He published his Advice to Farmers in 1841 and obtained both Scottish and English patents in 1842.

Sir John Bennett Lawes of England, who had also experimented with soaking bones and rocks in acid, bought Murray’s patent in 1846 and in time came to be known as the father of the fertilizer industry. His superphosphate of lime was thought to be such an improvement that, “as a testimonial,” wrote Evan Pugh, a young American chemist, the country’s farmers “gave him his choice, a Laboratory or its value of

Plate,” silver plates and tableware being a common reward at the time. He chose the laboratory, which was built on his estate at Rothamsted, England, and became a model for agricultural experiment stations in both England and the United States.

Pugh came to Rothamsted in 1857, fresh from studies in Germany with Wöhler and Liebig. There he occupied himself with the “nitrogen question.” Would nitrogen added to the soil as fertilizer increase the yield of a crop, or did plants take in and fix enough nitrogen from the air? An experiment in Paris, by chemist Jean-Baptiste Boussingault, had shown that plant nitrogen came from soil nitrates and ammonia, suggesting that nitrogen fertilizer was a good idea. Boussingault’s data, however, were found to be faulty, and rival work by another French scientist, Georges Ville, claiming that plants took nitrogen directly from the air, was taken up and popularized by the great Liebig.

Pugh sided with Boussingault. At Rothamsted, he wrote, “They have supplied me with about $500 worth of apparatus and we have been doing up the subject on a scale unprecedented.” In sterilized soil sealed under glass Pugh tried to grow three kinds of cereals and three kinds of legumes. Into the glass containers he pumped air, first washing it through both acid and potash, then adding back carbon dioxide. None of the crops grew. His results, he concluded, “indicate a confirmation of Boussingault. The evidence accumulates that Ville is an ass.” When he asked a visiting French scientist “how he accounted for Ville’s plants growing as they did,” the man answered, “Il a ajouté sans doute” (“Without a doubt he has added something”). Neither he nor Pugh was aware that what Ville might have added, simply by neglecting to sterilize the soil, were bacteria that did fix nitrogen out of air. In Germany, through his water-culture experiments, Sachs easily replicated Boussingault’s and Pugh’s results, and even Liebig was convinced. The nitrogen fertilizer industry—now of such importance to agriculture, both because of the greater yields it allows and the environmental problems it has caused—was born.

Chemistry was not the only ninteenth-century science to change—and be changed by—agriculture. In 1859 English naturalist Charles

Darwin published The Origin of Species, beginning a scientific debate that would last well into the 1930s and, in some circles, until today. In developing his theory of natural selection Darwin drew not only upon his observations of finches and tortoises in the Galapagos islands, but also on his knowledge of domesticated plants and animals. “We can not suppose that all the breeds were suddenly produced as perfect and as useful as we now see them,” he wrote. “Indeed, in many cases, we know that this has not been their history. The key is man’s power of accumulative selection: Nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to have made for himself useful breeds.”

As an authority, Darwin cites William Youatt who, he says, “was probably better acquainted with the works of agriculturalists than almost any other and who was himself a very good judge of animals.” Youatt, Darwin says, “speaks of the principle of selection as ‘that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician’s wand, by means of which he may summon into life whatever form and mould he pleases.’”

It was not The Origin of Species, but a later book of Darwin’s that inspired Luther Burbank to take up the magician’s wand. The man who would become known as the wizard of horticulture was 19 when he read Darwin’s The Variation of Animals and Plants Under Domestication, published in 1868. “It opened a new world to me,” he said simply. He was a truck gardener at the time, working a small plot of land next to his mother’s house and trucking his vegetables to New York City to sell. Upon reading Darwin he decided to distinguish himself from the rest of the vegetable carts in the market by creating new plants.

By 1873 he had built, as he put it, the Burbank potato, also called the Idaho potato, that russet-skinned, oblong standard used to make McDonald’s french fries. Potatoes are most often clones: they usually reproduce through tuber sprouts, so each potato plant is genetically identical to its parent. Yet sometimes a potato plant sets fertile seed. Discovering one of these rare seedpods at the edge of his garden, Burbank grew the 23 seedlings and selected 2. From their offspring he selected again, then sold his new Burbank variety to a Massachusetts seed salesman. With the $150 he earned he moved to California. There,

The art of grafting

beside “the world’s largest wheat field, an 80-mile-wide strip along the banks of the San Joaquin River,” says his biographer, Peter Dreyer, he envisioned orchards. He imported berries and plums and nuts from Japan, Panama, France, Chile, Argentina, Mexico, and Spain. He grew hundreds of stock trees, each holding dozens of grafts.

The technique of grafting had been known since ancient times. Yet in early America, grafting—just like molecular techniques today—was condemned as unnatural, as interfering with God’s plan. The popular sect called the Swedenborgians preached that all material things (rocks, plants, animals, and people) were reflections of the spiritual world and should not be tampered with. John Chapman, better known as Johnny Appleseed, believed that grafting violated the divine essence of an apple tree. He said: “They can improve the apple in that way, but that is only a device of man, and it is wicked to cut up trees that way. The correct

method is to select good seeds and plant them in good ground and God only can improve the apple.” When he gave away apple seeds, he insisted that the trees be allowed to grow freely so that they could express their spiritual reality. Orchardists, whose livelihood depends on a predictable crop, did not take Chapman’s seeds. Orchardists, writes Sue Hubbell in Shrinking the Cat: Genetic Engineering Before We Knew About Genes, plant “proven grafted stock and never, never, never save apple seeds to plant unless they have a speculative, adventuresome, experimental set of mind.” Because of the “perversely complicated” genetics of the apple, every tree that grows from a seed is a new variety—and most of them are commercial failures.

Fortunately for fruit lovers, the divine essence of the orange tree was not a consideration when the seedless navel orange was discovered as a sport or bud variation on a seedy variety in eastern Brazil in the early 1800s. In 1869 12 navel orange trees arrived at the U.S. Department of Agriculture’s new greenhouse in Washington, D.C., the gift of a Presbyterian missionary. To create the 12 new trees, horticulturalists had slit open the bark of a number of normal, seedy orange trees and carefully inserted into each wound a bud taken from a branch of the seedless sport. If the bud took, the branches of the stock tree were broken off to send all growth into the one new seedless branch. Every navel orange is thus a clone, a genetically identical twin, of that first Brazilian bud. In 1873 two such clones were sent to Riverside, California; from them sprang the California citrus industry.

Likewise, by such expedients as grafting dozens of different plums onto each one of his hundreds of stock trees (some of them almond trees), Burbank built up the California plum industry. Eleven of the plum varieties currently popular among California growers are Burbank’s.

Using tweezers and scalpels to emasculate plants, and paint-brushes, not bees, to transfer pollen to the female ovules, Burbank also made thousands, if not millions, of crosses. He crossed peaches with almonds, plums, and apricots. Plums he crossed with almonds and apricots, quinces with apples, and potatoes with tomatoes. To make his hybrid berries, he claimed to have crossed 37 different species in the genus Rubus. He was “the Henry Ford of the art,” Dreyer writes. “He

brought mass production to hybridizing, raising thousands of seedlings to obtain a single improved variety.”

Burbank destroyed his rejects in huge bonfires, lighting 15 in one year, with one fire alone destroying 65,000 hybrid berry bushes. Consigned to the fires were several hundred failed attempts at a white blackberry. Having found a yellowish berry (grown under the hyperbolic name Crystal White), Burbank decided to cross it with a black variety to see if, paradoxically, that would whiten the fruit. The first generation was still black. But when those plants were bred, a few of the offspring did bear whiter fruit. Seeds of these whitish berries were planted and, out of several hundred plants, five bushes bore nearly colorless fruit. The best of these became the Iceberg blackberry. The rest were burned.

Explaining his techniques in his 1893 catalogue, New Creations, Burbank announced, “We are now standing just at the gateway of scientific horticulture.” His fruits and nuts and berries “are more than new in the sense in which the word is generally used; they are new creations, lately produced by scientific combinations of nature’s forces, guided by long, carefully conducted, and very expensive biological study. Let not those who read suppose that they were born without labor; they are not foundlings, but are exemplifications of the knowledge that the life-forces of plants may be combined and guided to produce results not imagined…. Limitations once thought to be real have proved to be only apparent.” In a speech in San Francisco in 1901, he elaborated. Botanists, he said, had once “thought their classified species were more fixed and unchangeable than anything in heaven or earth that we can now imagine. We have learned that they are as plastic in our hands as clay in the hands of the potter or colors on the artist’s canvas, and can readily be molded into more beautiful forms and colors than any painter or sculptor can ever hope to bring forth.”

Burbank’s was the only plant breeder’s name to enter Webster’s Dictionary as a verb, “to burbank: to modify and improve (plants or animals), especially by selective breeding.” Yet he was not the only plant breeder feverishly introducing new varieties. Just as he imported his source material from Japan, Panama, France, Chile, Argentina, Mexico, and Spain, other breeders in America were using seeds and plants from Germany, the East Indies, Poland, Russia, and Ethiopia.

Since 1838 the U.S. Navy had sponsored official plant exploration expeditions, bringing home new types of vegetables, barley, rice, beans, cotton, persimmons, tangerines, roses, and wheat, which were then burbanked to produce varieties suitable for growing in America. The United States Commissioner of Patents had gained permission—and congressional funding—in 1839 to collect and distribute seeds, plants, and agricultural statistics. These seeds were, by the late 1880s, being quality-tested by the U.S. Department of Agriculture (USDA), which took over from the Patent Office in 1862, and distributed seeds and plants to breeders and farmers through the state agricultural experiment stations, which were modeled on England’s Rothamsted.

The turn of the twentieth century would see “the golden age of plant hunting,” with 48 USDA-sponsored expeditions in the next 25 years. These expeditions, and the foreign varieties they introduced, completely changed the crops American farmers planted and grew. Yields, however, remained static between 1860 and 1900. “The new varieties that flowed in an ever greater stream from public researchers were not raising average yields, but were permitting extension of production into new areas,” noted rural sociologist Jack Kloppenberg in his book First the Seed: The Political Economy of Plant Biotechnology, 1492-2000. “Advances in plant breeding served to maintain levels of yield that might otherwise have declined.” It was the scholarly insights of Gregor Mendel, not the brute-force approach of Luther Burbank, that increased crop yields without bringing more land under cultivation.

Mendel too had been inspired by Darwin: he bought every book Darwin wrote. What were these successive variations Darwin spoke of, he wondered? Mendel was an Augustinian monk; he lived in Brno, or Brünn, which was then part of the Austrian Empire and is now in the Czech Republic. In the monastery garden, Mendel grew peas with round, yellow seeds and ones with wrinkled, green seeds. He plucked the male stamens from a newly opened flower of the round and yellow type and brushed onto the female stigma pollen he had collected from a flower of the wrinkled and green type. Then he charted the results: how many round, how many wrinkled, how many yellow, how many green.

Mendel was not interested in just plants. He collected bees from

Europe, Egypt, and America and tried to hybridize them. He kept colonies of mice and crossbred different strains. In 1866 he published his laws of genetic inheritance. But his work was not to have an effect on agricultural science until the twentieth century, when his “factors of heredity” were named “genes.” “His mathematical approach, comparing the frequency of a trait in parents and offspring, was then unfamiliar in biology,” notes one scientist, “and so his discovery was ignored.”

The research that led to the rediscovery of Mendel was driven itself by curiosity about Darwin’s notion of species. In 1886 Dutch botanist Hugo De Vries had noticed the great variety of evening primroses growing on the coastal dunes of his native Holland. To explain their diversity in terms of Darwin’s theory, he formulated the idea of mutation (coining the word from the Latin mutare, to change), to mean an abrupt change that leads to a new species. He began breeding plants and worked out the pattern of inheritance of certain traits. Before publishing his results, he surveyed the earlier literature on heredity—and came across Mendel’s “Experiments with Plant Hybrids” from 34 years earlier.

This time Mendel’s work was not ignored. Although the concept of a gene was not yet clearly defined, the name “genetics” soon came to be applied to the Mendelian study of heredity. At last, said English biologist William Bateson, speaking at the Second International Conference on Plant Breeding and Hybridization held in New York in 1902, the plant breeder “will be able to do what he wants to do instead of merely what happens to turn up.” Before, hybridization gave only “a hopeless entanglement of contradictory results” and “incomprehensible diversity.” Now, using Mendel’s laws, breeders would have the power of control. “An exact determination of the laws of heredity,” Bateson said, “will probably work more change in man’s outlook on the world, and in his power over nature, than any other advance in natural knowledge that can be foreseen.” Bateson’s statement was remarkably prescient: Mendel’s laws did lead, if indirectly, to contemporary molecular techniques for plant improvement.

One of the few plant breeders not excited by Mendelism was Luther Burbank, who learned about it just after releasing another of his triumphs, the Shasta daisy. Mendel had little to offer the 50-year-old

breeder, unequaled in the variety of fruits and flowers he had developed. Burbank’s trial-and-error method was efficient enough for him. He stood “between the small-scale farmer-breeders who through most of history slowly but steadily built up mankind’s stock of useful plants, and the modern scientific hybridizer,” writes his biographer. In place of theory he had “a special gift of judgment,” according to De Vries, who had made a point of going to see Luther Burbank’s gardens.

Another geneticist who wondered about Burbank’s secret was George Harrison Shull. Shull worked at the Station for Experimental Evolution, established with the immense sum of 10 million dollars from the Carnegie Institution of Washington at Cold Spring Harbor, New York, in 1904. Charles Davenport, the director, was an advocate of biometrics, the application of statistics to evolutionary theory and an alternative to Mendelism. Biometricians measured minute differences between closely related organisms in order to explain just how evolution worked: why organisms were like their parents, yet different enough to support change. Davenport studied chickens (and later, humans, charting the inheritance patterns of hair, eye, and skin colors; the work would embroil him in the eugenics movement which sought to limit childbearing to the “fittest”). Davenport gave Shull, a former student of his, two tasks: to explain the science behind Burbank’s successful hybridizations, and to prepare a demonstration, using corn, of the simple inheritance patterns that Mendel had noticed in peas.

From 1906 to 1910 Shull spent part of each summer in California observing and questioning Burbank. They were not a good match. “You say, ‘He is always impatient of a conversation in which he does not do all or nearly all the talking,’” Robert Woodward, president of the Carnegie Institution, wrote to Shull. “Now, singularly enough, this is precisely the remark he has made to me concerning you.” Shull was a scientist; Burbank had “the work habits of an artist,” his biographer notes. His recordkeeping system “was haphazard in the extreme.” He was secretive and suspicious, searching his workers’ pockets for seeds each evening as they left the job. Shull eventually gave up in frustra-

tion, never publishing his report. Burbank’s success was due not to any scientific theory, he concluded, but to his “vivid imagination,” “persistency,” “concentration,” “sensitivity to variation,” and “exceptionally keen eye for what the market wanted.” When asked, for instance, if he could breed a good-tasting decaffeinated coffee hybrid, Burbank replied that “it would involve years of experiments in the tropics.” Besides, he added, “Would coffee be used, except for the exhilaration accompanying the caffeine? I think it would, but this is for someone else to decide.” A few years later, a method was patented to extract caffeine from unroasted beans using steam and the solvent benzol. The resulting product was sold in France as Sanka (sans caffeine).

Burbank’s hybrids had nothing to do with his own work, Shull felt, in the new field of genetics. Even when both men were experimenting with corn, Burbank crossing Indian corn with teosinte, which he believed was corn’s ancestor, and Shull attempting to demonstrate Mendelian inheritance, the two didn’t discuss their work. “How amazing,” wrote geneticist and historian Bentley Glass, “that there was really no meeting of minds in the very area in which it might most reasonably have been expected!”

In New York, Shull crossed round-kernelled corn from his father-in-law’s farm in Kansas with wrinkled corn from a farm near the lab. Corn, like Mendel’s peas, has both male and female parts on one plant, though for corn the two sexes are far apart while for peas they are in the same flower. To cross two corn varieties, Shull plucked off the tassels of one variety, letting the other provide the pollen to fertilize the female flowers; he was thus assured that any ears resulted from a cross between the two.

The Kansas corn had full, round kernels because those kernels held more starch: being a long and bulky polymer, the starch filled the space inside the kernel completely. The New York kernels were wrinkled and collapsed because of a mutation that blocks the conversion of sugar to starch. This type is our modern sweet corn. The kernels on the crossbred ears that Shull harvested at the end of the summer were all round, starchy kernels. Two versions of the same gene determine whether the kernels are wrinkled and sugary or full and starchy. (The word “gene,” in this modern meaning, would not be used until 1909; Shull still called

them hereditary factors.) The starch-making version, or allele, was dominant, while the mutant sugar-making allele was recessive. If pollen from a starchy plant is brushed onto the silks of a sugary plant, each resulting kernel receives a functional starchy allele from the pollen parent and a nonfunctioning sugary allele from the ear-bearing parent. Such a kernel would be heterozygous (from the Greek words for “different” and “yolk”).

When Shull took these heterozygous kernels, grew them, and crossed them with a plant that had the same sugary allele from both parents (and so was homozygous, from the Greek for “the same” and “yolk”), half of the kernels on each ear were round and half were wrinkled. The traits, each determined by a different form of a single gene, had segregated from each other and the wrinkled trait had reappeared. The experiment thus provided the demonstration of Mendelian inheritance that Davenport had requested.

But Shull also noticed that the number of rows of kernels on the two types of ears—starchy or sugary—was quite different. Curious about how this second trait was inherited, he cross-pollinated plants grown from the different parent ears and counted the number of rows on the resulting ears. He also self-pollinated the plants. This self-pollination, or inbreeding, Shull saw, was not good for the plants. The progeny of self-pollinated plants were smaller and more disease-prone and had smaller ears. Yet when he crossed these puny inbreds and grew the kernels, he was startled to get much healthier plants that produced much bigger ears.

He published these results in 1908. A year later he explained how his observations could be put to practical use in a short paper called, “A pure-line method of corn breeding.” He admitted that this method of producing seed corn was probably more expensive, and he was unsure if the increase in yield would be enough to cover the cost. “These are practical questions which lie wholly outside my own field of experimentation,” he concluded, “but I am hoping that the Agricultural Experiment Stations in the corn-belt will undertake some experiments.”

The Agricultural Experiment Stations were not thrilled. Shull’s method was “impractical,” “too complex,” and “not cost-competitive,”

being three times more expensive than open-pollinated corn. Producing enough seeds of the inbred lines would be a bottleneck, making it harder for a farmer to get seed. Farmers were accustomed to saving corn from their own crops for planting the next year. They did buy seed corn occasionally to freshen their own supply, but with the new hybrid varieties they would have to buy new seeds every year. Moreover, the technique, wrote one USDA breeder, echoing Johnny Appleseed and in turn to be echoed by Prince Charles and Congressman Kucinich, did “violence to the nature of the plant.” It was “dangerous.” Those experiment stations that did try the technique, writes Charles Heiser in Seed to Civilization, thought the inbreds were “such sick-looking plants” that they grew them only “in out-of-the-way places where farmers would be unlikely to see them.” Otherwise, “they would think the breeders were working in the wrong direction.”

Yield, in fact, was not the standard by which corn was judged in the early 1900s; beauty was. At the corn shows popular throughout the country, a farmer would enter a single perfect ear, hoping to win an expensive tool or machine. At the National Corn Exposition each year, one ear would be named Champion of the World. The judges, many of whom were university scientists, would rank the ears on aesthetic factors, even though they knew that beauty had little to do with performance. A prize-winning ear, according to one show card, was “10¹/₂ inches long, 7 ¹/₂ inches in circumference, with 20 or 22 straight rows of kernels carried out to the tip, and with a well-rounded butt. The kernels had to be moderately wide, keystone in shape, deep, plump at the tip, and without any trace of being shrunken or blistered.” Some judges (especially in Iowa and Illinois) gave extra points if the kernels were “horny and shiny.” By 1910 it was clear that the characteristics weighted heavily on the show card actually lowered yield, but the shows were so popular among farmers that change came hard.

The breakthrough occurred in 1917, the same year that the Hungarian agricultural engineer (and owner of the largest pig farm in Europe) Karl Ereky coined the term “biotechnologie.” It was also the year of the Russian Revolution (with its slogan “Bread and Peace”) and the Plow to the Fence for National Defense campaign in support of World War I. In that year Donald F. Jones produced a Mendelian explanation for Shull’s results.

Jones was a student of Edmund M. East, who earlier, while at the Connecticut Agricultural Experimental Station, had pronounced Shull’s hybrid corn idea “impractical,” “too complex,” and “not cost-competitive.” Jones’s double-cross hybrid method, published in 1918, solved the practical, economic problem (though not the complexity). Rather than Shull’s two inbred parent lines, Jones used four. The plants that produced the seeds farmers would buy were not the puny, sickly inbred lines (cause of the bottleneck East predicted), but more productive single crosses. A few bushels of single-crossed seed would produce a thousand bushels of double-crossed seed which, when planted by farmers, would show the increased vigor Shull discovered, now called heterosis.

Yet Jones’s double-cross hybrids still had no chance of winning at a corn show: the ears were far from the show ideal. Farmers were also not convinced that buying seed every year would benefit anyone other than the seed dealer. Henry A. Wallace, an editor, with his father, Henry C. Wallace, of Wallace’s Farmer, came up with the solution in 1919. In the pages of the magazine, he suggested that the corn show branch out into a new contest: a yield test under controlled conditions. Iowa State University picked up on the idea and in 1920 started the Iowa corn yield test. Four years later Wallace won the gold medal with Copper Cross, the progeny of two inbred lines, one of which came from Jones. In 1926 Wallace founded the Pioneer Hi-Bred Corn Company, marking the transition of the seed dealer’s market from backyard gardeners to farmers, who previously had supplied almost all of their own seeds, saving some from each harvest.

In 1933 only 1 percent of the corn grown in the United States was hybrid corn. The average yield was 23 bushels per acre. Then came a drought that destroyed most traditional varieties. Plant breeder Don Duvick, who recently retired from Wallace’s Pioneer Hi-Bred company as Vice President for Research, recalls from his childhood:

By 1940 30 percent of U.S. corn was hybrid; the average yield had risen slightly, to about 30 bushels per acre. By 1970, when Ingo Potrykus began his genetic studies of petunias, 96 percent of U.S. corn was hybrid. The average yield was a remarkable 72 bushels per acre.

Though he was most likely not in the audience when Luther Burbank lectured in 1925 at the First Congregational Church in San Francisco, Henry Wallace might have agreed when Burbank proclaimed, “What a joy life is when you have made a close working partnership with Nature, helping her to produce for the benefit of mankind new forms, colors, and perfumes in flowers which were never known before; fruits in form, size, color, and flavor never before seen on this globe; and grains of enormously increased productiveness, whose fat kernels are filled with more and better nourishment, a veritable storehouse of perfect food—new food for all the world’s untold millions for all time to come.”

The year Wallace founded his Pioneer Hi-Bred Corn Company, the world population was 2 billion. By 1950, when the first mutation-bred crops formed by irradiating seeds were being sown, and F. G. O’Mara was using colchicine to develop the fertile wheat-rye hybrid triticale, the world’s population had grown to 3 billion. Most of the fertile land on Earth was already in production by then and the clearing of new agricultural land would be balanced, over the next 50 years, by loss of fertile land to urbanization, desertification, and salinization. Meanwhile, more than 70 million human beings were added to Earth’s population each year. Pundits were predicting mass starvations: up to a billion deaths.

Wallace had much to do with the fact that this food crisis was averted. In 1943, having served as U.S. Secretary of Agriculture from 1933 to 1940, he was the Vice President of the United States under

Roosevelt. He tried to persuade Congress to provide agricultural aid to Mexico. Having failed, he turned to the Rockefeller Foundation, the philanthropic organization pledged to “applying science to benefit mankind.” An agreement was made with the Mexican government to support a new kind of cooperative technical assistance program. Its first objective would be to improve local crops, including corn, wheat, potatoes, and beans. Mexican students would be trained in agricultural science and helped to set up their own research programs.

Norman Borlaug had just completed a doctorate working on rust, a fungus that plagues wheat and other crops, and was looking for a job. In 1944 he became director of the wheat program, “a job for which there was little competition, backwater Mexico in the 1940s not being an eagerly sought-after posting,” notes one writer. In his 1970 Nobel Peace Prize lecture, Borlaug recalled, “At that time, Mexico was importing more than 50 percent of the wheat that it consumed, as well as a considerable percentage of its maize. Wheat yields were low and static, with a national average yield of 750 kilos per hectare, even though most of the wheat was grown on irrigated land.” The soils were “impoverished,” and chemical fertilizer “virtually unknown.”

Research at the Mexican institute “from the outset,” said Borlaug, “was production-oriented and restricted to that which was relevant to increasing wheat production. Researches in pursuit of irrelevant academic butterflies were discouraged. As soon as significant improvements were made by research, whether in varieties, fertilizer recommendations, or cultural practices, they were taken to farms and incorporated into the production programs. We never waited for perfection in varieties or methods, but used the best available each year and modified them as further improvement came to hand.” Borlaug and the other researchers demonstrated the new techniques on the farms themselves. “This forced the research scientists themselves to consider the obstacles to production that confronted the farmers.”

When World War II ended and nitrogen-based explosives were no longer needed, the price of nitrogen fertilizers fell and their use increased. Plants grew bigger and yields climbed, but soon a new problem arose: lodging. The tall stalks, topped by heavy heads of grain, fell over in wind or rain and could not be harvested. By 1953 Borlaug was

searching for a small, sturdy wheat variety that the wind and rain wouldn’t knock down.

A few years before, a USDA scientist, S. C. Salmon, had brought seeds of Norin wheat, a group of dwarf varieties, home from Japan. As a visitor to Japan had remarked back in 1873, “The Japanese have made the dwarfing of wheat an art. The wheat stalk seldom grows longer than 50 to 60 centimeters. The head is short but heavy. No matter how much manure is used, the plant will not grow taller; rather the length of the wheat head is increased. Even on the richest soils, the wheat plants never fall down.” Salmon shared the seeds with several breeders, including a research group at Washington State University who bred a hybrid strain habituated to the Pacific Northwest. It produced a world record of 216 bushels per acre (over 14,000 kilos per hectare). The Washington group sent seeds of their champion hybrid, as well as some of the original Norin seeds, to Borlaug. His first crop of the dwarf wheat, planted near Mexico City, was lost to rust—the very fungus he had studied for his Ph.D. research. The next year he planted near Mexico’s west coast, where the wheat did well. “Next he crossed his new dwarf strain with everything else he had around,” according to the authors of Biology: A Human Concern, “and this was the beginning of the revolution, so to speak.” The revolution was the Green Revolution.

As Borlaug explained in his Nobel lecture, “Through a series of crosses and re-crosses begun in 1954, dwarfness was incorporated into the superior, new-combination Mexican types, finally giving rise to a group of so-called dwarf Mexican wheat varieties.” By changing the plant’s architecture to emphasize a short, sturdy stalk, the dwarfness trait allowed the wheat to produce heavier seed heads—given enough water and nitrogen—without falling over in a breeze. In addition, the plants were not affected by length of day (and so could grow at a range of latitudes) and were highly resistant to wheat rusts. The result, in Borlaug’s terms, was a “yield blast-off.” A few seasons after the new variety was introduced Mexico became self-sufficient in wheat. When introduced into Pakistan and India, the wheat had the same yield-boosting effects.

At the same time as Borlaug was searching for dwarf wheats, researchers at the new Ford- and Rockefeller-funded International Rice

Research Institute (IRRI) in the Philippines were looking for dwarf rices—what came to be known as “miracle rices.” In 1963 Hank Beachell, a retired USDA scientist, found a short, thick-stemmed rice plant in row 288 of an IRRI experimental field. It had come from a cross between a short, stiff-strawed variety called Dee-geo-woo-gen from Taiwan and a taller, vigorous, pest-resistant variety called Peta from Indonesia. It was the eighth cross made, so Beachell named it IR8.

Combining the vigor of Peta with the shortness of Dee-geo-woogen, IR8 grew more branches, or tillers, each of which produced grain, giving each plant a higher yield. Like Borlaug’s wheat, IR8 was insensitive to day length; it could mature 60 days sooner than other varieties, allowing farmers to grow two crops a year instead of one.

The genetic change behind this miracle rice was not discovered until 2002. Ashikara Motoyui and Matsuoka Makoto of Nagoya University in Japan reported that they had isolated the gene (called semidwarf 1 or sd1) that was responsible. This gene codes for a protein needed to produce a plant hormone. The sd1 allele contained a large hole, a deletion: it was missing 383 pairs of nucleotides, or base pairs, out of a total of 1,170. This mutation made the gene useless—with extraordinary consequences. Nitrogen fertilizer normally increases both the amount of grain a rice plant produces and its height, the same way it does in wheat. Tall rice, like tall wheat, is vulnerable to lodging, being knocked down by wind and rain. The IR8 plants, however, stayed short when fertilized and they stayed upright until they were harvested. Their sturdiness in itself increased yield. But there was an added bonus. Because the plant did not expend as much of the energy it harvested from the sun in growing stems and leaves, more went into making grain. The fraction of a plant’s total weight that is in the grain is termed its harvest index. The harvest index of IR8 and the other new semidwarf rice varieties increased from about 30 percent to more than 50 percent.

When IR8 was released to farmers in 1966 it changed Asian agriculture. IR8 was rapidly adopted in the Philippines, then India, Pakistan, and Indonesia. A year later Indian scientist Gurdev Singh Khush joined the IRRI staff. Khush had a hand in breeding more than 300 rice varieties, including IR36, which, according to IRRI, was “the most

widely planted variety of rice, or of any other food crop, the world has ever known.” With the new varieties, rice yields more than doubled from the mid-1960s to 1990 throughout Asia. Upon Khush’s retirement in 2001 the IRRI annual report claimed that “in any rice field, anywhere in the world, there’s a 60 percent chance that the rice was either bred at IRRI under his leadership or developed from IRRI varieties.” Said Norman Borlaug, “The impact of Dr. Khush’s work upon the lives of the world’s poorest people is incalculable.”

It was to Khush’s program at IRRI that Karabi and Swapan Datta came, straight from Ingo Potrykus’s laboratory, in 1993. And it was here that Golden Rice was sent in 2001, to be grown in a high-security, Biosafety Level Four greenhouse.