The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis (20 page)

Mendel had shown that recessive genes could pass through multiple generations, answering Darwin’s question about “why the child often reverts in certain characters to its grandfather or grandmother.” His result countered the notion of blended inheritance. Mendel was lucky that single genes control a pea’s shape, a pod’s color, and a stem’s length; otherwise he would not have
gotten his beautiful ratio. Many characteristics, such as human eye and skin color, do not follow this pattern.

Mendel’s experiments ended when he took on an administrative role as abbot at his monastery. Although he sent his results to Darwin, Darwin either never read Mendel’s letter or dismissed it, and Mendel’s paradigm-changing results lay dormant for
more than thirty years. Around 1900, three other botanists, working in the Netherlands, Germany, and Austria, came to the same conclusion and
rediscovered Mendel’s experiments. Mendel took his rightful place as the father of genetics, although he had died before his work was rescued from obscurity. His painstakingly tedious work of picking apart thousands of flowers in the monastery’s garden set the stage for an era of breeding that was more predictable and controllable than the trial-and-error efforts of earlier generations of farmers.

Together Darwin’s and Mendel’s experiments underpinned the work of twentieth-century plant breeders to produce commercial seeds with skyrocketing yields. The guiding principles were to avoid inbreeding, to take advantage of hybrid vigor, and to produce seeds with predictable outcomes for the progeny.

Hybrids Invade the Corn Belt

Corn as feed for meat-producing cows, pigs, chicken, and fish. Corn for corn syrup to sweeten beverages. Corn oil to fry potatoes or onion rings. Corn is the behind-the-scenes staple of today’s American diet—indeed, the United States produces more corn than any other country, and corn now grows on one out of every four acres of
farmland in the country.

None of this would have come to pass if not for Mendel’s discovery or corn’s particular anatomy. The tassels that sprout from the top of a cornstalk are the pollen-producing male part of the plant. Under normal circumstances, wind carries the sperm-containing pollen through the air, to land on the silk emerging from another corn plant’s ear. The pollen travels down the silk, and the sperm in the pollen fertilizes an egg, which grows into an embryo inside a kernel. In this way, each kernel in each ear of corn is fertilized by one of the millions of pollen grains from the tassel of its own or a neighboring cornstalk.

Plant breeders can manipulate the match between the sperm and the egg by planting the desired pollen producer near the plant to be fertilized, and cutting off or covering the tassel of the pollen-receiving female. That way, there’s little chance that pollen can fertilize an egg on the same plant, and a high chance that pollen from the nearby plant will fertilize an egg on the plant with the cut or covered tassels. The designated female plant can only receive pollen from the designated male plant.

Mendel experimented with corn after his work with peas, as did the botanists
who later rediscovered his work. But the plant garnered more than academic interest. During the nineteenth century, as Europeans fanned across the North American prairie planting wind-pollinated corn, plant breeding was the purview of “seed men.” Seed men selected ears with the qualities they liked—early ripening, bright yellow kernels, resistance to disease, or good-sized ears—and sold dried kernels from
these
ears as seed to farmers. Farmers, in turn, displayed their best products grown from these seeds at corn shows across the Corn Belt, providing more material for the seed men, who continued to cross varieties in hopes of better crops. Despite all the efforts of seed men and farmers, one feature of corn remained stagnant: its yield. From the 1860s until the 1930s, an acre of corn yielded fewer than
twenty-five bushels.

In the early decades of the twentieth century following the rediscovery of Mendel’s groundbreaking results, a cohort of American colleagues—among them Edward Murray East in Connecticut and Rollins Adam Emerson in Nebraska—applied Darwin’s revelations and Mendel’s findings to the quest to breed better corn. The impetus, besides the intellectual challenge, was the promise of financial gain: with higher-yielding corn, farmers would be able to feed livestock more economically, and raising livestock was the main point of all that Midwestern corn. Nicknamed “prophets of plenty” by a biographer of this small group of determined men, the hybrid-corn makers combed corn shows in county fairs across the farm country to find “
freak” seeds for their experiments.

These freaks had a range of unusual traits, including striped leaves, branching ears, and dwarfed stalks. The prophets of plenty were trying to figure out which traits might follow Mendel’s pattern, so that they could reliably predict the characteristics of the progeny. If they planted rows of corn with the same characteristics next to each other to produce inbred varieties, mimicking what Mendel had done with his forceps to get his true-breed pea plants, then they would be able to take advantage of Darwin’s “good effects of crossing.” They would cross these inbred lines, produce hybrids, and sell the hybrid seeds to farmers. The result, in theory, would be hybrid vigor, with plants that showed more vigorous growth and yielded more than corn fertilized in the open by wind-blown pollen. But there was a problem: the “evil effects of close inbreeding” meant that the feeble, inbred varieties did not generate enough kernels
to cross, making the prospect of producing hybrids on a commercial scale impractical. One of East’s students, Donald Jones, figured a way around that problem. He fashioned hybrid seeds from four inbred lines instead of two. He first crossed two sets of inbred lines, then again crossed the progeny of these two sets. With seeds in sufficient quantity from hybrid vigor in the first crosses, the double-cross method made commercial production of
hybrid seeds worthwhile.

In 1926, future US vice president Henry Wallace founded Hi-Bred Corn Company in Iowa, the first to sell hybrid seeds to farmers. Hybrid seeds took off like wildfire throughout the Corn Belt, encouraged by New Deal programs during the Great Depression. Yields were phenomenal. By the mid-1940s, all of the corn planted in Iowa was from hybrid seed. By the mid-1950s, hybrids were planted on nine out of ten
acres of corn in the United States. By 1960, corn yields had nearly doubled from the early decades of the century when blowing
pollen had fertilized crops. Ultimately, about half the staggering explosion in corn yields in the twentieth century could be
traced to hybrid seeds. The other half of the growth came from the use of chemical fertilizers, pesticides, and new machinery. The legacy of the early twentieth-century pivot to hybrids is clear to anyone gazing out the window of a flight across the Midwestern Corn Belt, where big, mechanized, chemically fertilized, high-yielding farms dominate the view.

Mendel’s discoveries and hybrid vigor handed a huge opportunity to commercial seed companies. Because the vigor of a hybrid diminishes with the second generation, farmers were now locked into purchasing new hybrid corn seeds each year. They became captive customers. In return, their fields produced many times more corn than in the years before hybrids. Gone were the days when farmers saved seeds for the next year’s crop.

Following the 1930s’ ascent of hybrids in the United States, other parts of the world saw massive upswings in corn yields as well. Farmers
in the industrialized world adopted the hybrid seeds along with the fertilizers and the new machinery. Corn yields doubled in Germany from 1965 to 2000, tripled in Canada from 1940 to 2000, and quadrupled in France
from 1950 to the mid-1980s. Here was the Big Ratchet in action. And corn was not the only grain to surge as Mendel’s principles spread far beyond his monastery’s garden.

Short Beats Tall

In his 1898 speech, Sir William Crookes had called upon the chemists to find a way to synthesize nitrogen from the air. In that same speech, he also raised an alarming specter, predicting that “within a generation the ever-increasing population of the United States will consume all the wheat grown within its borders,” causing a “scramble for a lion’s share of the
wheat crop of the world.” But the prophecy was not to be.

Wheat, the wild grass first domesticated in the Fertile Crescent, came to the treeless, flat, dry prairie of the American Great Plains with European settlers in the mid-1800s. At first, the hazards of droughts, wind, and dust storms, as well as the plagues of grasshoppers and plant diseases, spelled disaster for the settlers’ crops. Both the crops and the settlers were unaccustomed to the harsh conditions. A few decades later, Mennonite families from the Crimea settled the plains, bringing seeds that hailed from a little valley in Turkey. The so-called Turkey wheat was one of many hundreds of varieties around the world that farmers had coaxed through trial and error to adapt to their particular climate and soils. Both the Mennonites and the Turkey wheat proved to be well-adapted to the plains. Turkey wheat became the leading variety over the next quarter century and spread into Nebraska, Kansas, northwestern
Texas, Oklahoma, and Colorado.

As Mendel’s principles came into the limelight in the early twentieth century, commercial interests were piqued to supply the increasingly global market for wheat, just as their counterparts in hybrid corn had
opened up a new entrepreneurial frontier by selling seeds to farmers. Fertilizers and machinery were improving yields; now it was time for the new science of genetics to make its mark. In the words of Willet Hays—founder of the American Breeders Association, which brought together plant breeders in universities and government officials from the recently formed Department of Agriculture to collaborate on breeding—“as science, inventive genius, constructive skill, business organization, and great market demands at home and abroad have pushed forward things mechanical, so should ways be found of improving these living things which serve as machines for transforming the substance of soil and air and the forces of the sun’s rays
into valuable commodities.” He went on to claim in the dramatic language of the day that “the energy of the generative cell, and its development into the mature plant or animal, is more abstruse and more profound than the mechanism of the mightiest locomotive. Here the controlling forces of one generation of these living machines plunge, spirit-like, through the microscopic generative cell and rise in progeny, possibly the potencies of a single Shakespeare-like individual to be multiplied a million fold as a valuable
new variety or breed.”

The search for new varieties of wheat with higher yields posed a different challenge to plant breeders than corn had presented to East and Emerson. Wind is not the agent that pollinates wheat as it is for corn. Like peas, a wheat plant pollinates itself. The male pollen and the female egg are in the same floret, and the match is made even before the flower opens. That evolutionary adaptation means that wheat is well-suited for arid places such as the Great Plains, as there’s little chance that wind will dry out the pollen. But this same biology made commercial production of wheat hybrids untenable. Hybrid corn simply required planting rows of designated male and female wind-pollinated corn next to each other. With self-pollinating wheat, a plant breeder had to take the pollen from one variety and fertilize an egg from another by hand, as Mendel had done with his peas, which is not so convenient for producing massive
quantities of hybrid seeds.

Although the biology meant that plant breeders could not easily take advantage of hybrid vigor, they had some success with crafting new varieties with desirable traits—such as strong straw that didn’t flatten in the wind—by painstakingly crossing wheat strains by hand and reaping seeds from the resulting cross. The new varieties, some crossed from foreign strains, had many names, including
Marquis, Blackhull, Fultz, and Fulcaster. Although these new varieties did improve yields a bit, most of the upswing in the amount of wheat came from farmers expanding into new wheat fields rather than farmers harvesting more wheat from each field.

The breakthrough came in the 1940s. Horace Capron, former US commissioner of agriculture, had reported on the benefits of a shorter stalk that he had seen in Japan as long ago as 1874. The wheat crop, he wrote, had “a short, but compared to the straw, heavy head. The stalk seldom grows higher than 2 feet, and often not more than 20 inches. . . . Certain it is, that on their richest soils and with the heaviest yields the wheat-stalks never fall down and lodge on the ground, to the great injury of the
crop, as in the United States.” Plant breeders didn’t pay much attention to the advantageous trait until chemical fertilizers, irrigation, and machines started to bump up yield. Knee-height rather than waist-height wheat-stalks made all the difference. Shorter wheat plants had sturdier stalks that tended to stay upright despite the wind and the weight of the growing plant, which meant that less wheat fell over to rot in wet soil or to be eaten by rodents. Varieties with shorter and stiffer straw, with names like Wichita, Pawnee, Comanche, and Triumph, started to replace their taller counterparts, and
yields took off.

In Search of the Soybean

Soybeans, the third in the triumvirate of the industrializing agriculture of the Midwest in the early twentieth century, took another path. The
Chinese first domesticated the bean in the northeastern part of China several thousand years ago, and it had gone on to become one of the sacred grains of Chinese civilization, along with
rice, wheat, barley, and millet. Trade routes spread the bean throughout Asia, where miso, tempeh, and tofu, all produced from high-protein soy, became a cornerstone of nutrition in the region.

Missionaries and scholars brought soybeans to Europe in the late sixteenth century and throughout the seventeenth, but the crop failed to take a prominent place in European agriculture. Samuel Bowen, a seafaring employee of the East India Company, first carried soybeans to North America from China by way of London. He planted the seeds on his plantation in Georgia and applied for a patent to make soy sauce and noodles. Benjamin Franklin sent seeds from London to plant in his garden near Philadelphia. But again the crop did not take root in North America. Farmers grew it mostly for forage to feed animals and, as with clover, for the beneficial, nitrogen-fixing effect of the bacteria living on the plants’ roots.