As July 4th activities formally usher in the summer picnic season, U.S. sweet corn sales will skyrocket. Corn on the cob is the perfect finger food—at least for people not obsessed with counting carbs. Quintessentially American, corn—or maize as it’s known outside the United States—evolved somewhere around Panama or Mexico some 5,000 to 7,000 years ago, then spread throughout the Western hemisphere. Its subsequent cultivation has been widely credited with letting pre-Columbian communities throughout the Americas settle down and launch their civilization. Eventually agriculture, based on corn, moved into what would become the United States.

NATIVE AMERICANS. These exotic Latin American maize varieties, collected by the U.S. Germplasm Enhancement for Maize project, are used by scientists as potential sources of genes for improved yield, vigor, taste, or resistance to blight. They also illustrate the colorful stock that might have served as the basis of initial maize exports around the time of Columbus. Keith Weller/USDA/ARS

CORN RICH. The temperate climate of states in the Midwest’s Corn Belt help them achieve bonanza yields of maize—and largely account for the United States’ being the world’s leading producer of this grain. Fertilizers and pest-control agents applied in the Midwest further enhance the yield. Bruce Fritz/USDA/ARS

MAIZE EXCHANGE. These farmers in China’s Shandong Province are delivering seed corn to a regional grain exchange. Erika Meng/CIMMYT

CORN CRIB. Most maize in China still goes to feed livestock. Farmers usually store it in outdoor bins, like the one shown here. Erika Meng/CIMMYT

However, corn (Zea mays) has won gustatory converts far from its natal continent. In some parts of Asia, it’s been grown for so long that farmers there consider it an indigenous species. Certainly, that’s what Anne E. Desjardins discovered some 30 years ago when the U.S. Peace Corps program assigned her to the Lamjung district of Nepal to teach science. There, farmers every spring planted terraced fields high in the Himalayas with orange, red, white, and multicolored maize.

Sometimes, workers ate popcorn for lunch, along with beer made from fermented maize. More often, she found, the brightly hued kernels would be ground to make a thick porridge that accompanied lentils or a vegetable curry.

Her neighbors were convinced that their maize, or makai, is indigenous to the Himalayas, as rice, millet, and buckwheat actually are, she notes in a new report posted on the National Agricultural Library’s (NAL) website. Desjardins, who is now a USDA chemist, and NAL’s Susan A. McCarthy, trace the long road that maize took from the New World to Asia. Their survey begins with Christopher Columbus’ 1492 discovery of maize and then focuses primarily on historical records compiled during the 16th to 18th centuries.

Although some anthropologists have argued that there must have been concurrent evolution of maize in the Americas and elsewhere, the authors found no historical reference to the plant being indigenous outside the Western hemisphere. They conclude that it rapidly spread eastward across Eurasia and reached China less than 60 years after Columbus introduced it into Spain.

Today, the International Maize and Wheat Improvement Center—known by its Spanish acronym, CIMMYT—puts much of its effort into improving maize for cultivation in Asia, Africa, and South America. In southern Africa, poor people rely almost solely on that grain. Elsewhere in the developing world, its popularity is also high and growing.

Indeed, CIMMYT noted 3 years ago, “Demand for maize in developing countries is projected to surpass both wheat and rice by 2020, meaning that maize supplies for those areas must nearly double.”

New World prize

Sixteenth century historians such as Friar Bartolome de las Casas quote Columbus in 1492 as reporting that he had encountered Indian corn in the Bahamas and a related, domesticated maize in Cuba, Desjardins and McCarthy note.

In fact, it would have been hard for the explorer not to stumble onto the cereal grain during his travels. At that time, maize—in its many colors and cultivated varieties—was the most widely grown domesticated plant in the Americas (SN: 4/17/93, p. 248). Its range already extended from southern Canada to southern South America. Some tribes were planting it at sea level, others at elevations above 11,000 feet.

“Columbus had no way of knowing that maize was far more valuable than the spices and gold he had hoped to find, or that it represented . . . the most remarkable plant-breeding accomplishment of all time,” said paleoethnobotanist Frances B. King, formerly at the University of Pittsburgh, in an interview in 1993.

However, the explorer was sufficiently impressed with the grain to have had his crew make a brochure describing its attributes. They called corn an unusual but tasty chickpea-shaped grain used to make bread. Some of his ships returning to Europe in 1494, midway through a second expedition, brought back the brochure. This document became the first record of corn to reach Europe. Later, Columbian expeditions would find maize fields in Central America and in what is now Venezuela. By 1498, Columbus’ diaries would note that maize was already under cultivation in Spain.

As subsequent Spanish armadas sent troops to conquer parts of Mexico and Central America, Europe continued to import maize. For at least a half-century, many Europeans considered the Americas to be the Eastern edge of Asia, where they knew Ottoman traders conducted extensive overland commercial traffic. So, the new grain acquired the colloquial name of Turkische korn or Turkish wheat, Desjardins and McCarthy note. Some German texts in the mid-1500s credited the Turks with bringing sacks of the brightly hued kernels to Europe from Asia. The grain’s New World roots were soon reestablished as maize’s popularity spread northward into Britain. By the 1600s, many European cuisines had permanently embraced corn, making it a dietary staple.

The Agriculture Department researchers note that 1502 is the earliest date for a reference to maize in west Africa—at least in texts for which English translations exist. Fifteen years later, accounts describe maize in Egypt. A few years after that, reports emerged of maize, also known as Ghiny-wheat, being raised as food for slaves near the Congo and for residents of the Cape Verde Islands. By the 1600s, Dutch traders confirmed maize in these regions, although they initially referred to it by the then-outmoded European term—Turkish wheat.

Along the Silk Road

And what of maize along the Turkish caravan routes to the East of Europe? Desjardins and McCarthy cite texts describing records compiled by 16th century botanists, such as Leohard Rauwolf, and other travelers who confirmed the cultivation of maize in Iraq as early as 1574.

For at least a millennium, caravan routes linked trade in China and South Asia with the Middle East. These long, treacherous paths through arid steppes and rugged, winding mountain passes collectively came to be known as the “Silk Road.” Beginning in the early 1500s, maize became a commodity bartered by traders plying this Silk Road.

Published reports noted that by the mid 1500s, the grain was growing in South Asia—in what is now Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka. Muslim traders were probably responsible for much of its initial dispersal in these lands, the Agriculture Department researchers note, because the grain suddenly takes on the name makka—or some variant of makka—meaning “grain of Mecca”. Portuguese and British trading companies eventually fostered settlements in the region, which increased even further the demand for maize cuisine and the grain’s cultivation.

Though maize was growing in China by the 1500s, it doesn’t appear to be an indigenous species there, Desjardins and McCarthy note. One clue is the various names they turned up for the grain—fan mai (meaning foreign or barbarian wheat), hsi fan mai (western barbarian wheat), and Jung shu (grain of western barbarians). In some regions, it also took on a name that included jade. This, the authors note, suggests “an association with imperial jade, which was imported into Ming China from the West by two ancient trade routes.”

That was then. . .

Today, maize production continues to flourish.

Although U.S. diners tend to think of the grain as a distinctly American crop from the Midwest Corn Belt, two-thirds of all hectares planted with this grain reside in developing countries. Grown in more countries than any other crop, farmers globally harvest some 560 million tons of maize each year.

A quartet of countries dominate the developing world’s production, accounting for more than half of its maize-growing lands. China, with 26 million hectares (ha), trails only the United States in production of maize. With 12 million ha, Brazil is the second leading maize producer among developing nations. Mexico ranks third with 7.5 million ha, and India comes in right behind with 6 million ha.

Maize production in these and other developing counties is, moreover, likely to grow substantially as incomes climb, according to CIMMYT scientists Prabhu L. Pingali and Shivaji Pandey. The reason: Rising incomes fuel “a rapid increase in the demand for maize as livestock feed (especially for poultry and pigs),” they say in a chapter of a report by their institute.

This trend is especially strong in East and Southeast Asia, where maize demand is expected to grow from 1995 levels of 150 million tons to 280 million tons by the year 2020. Even in areas of the world where poverty reigns, such as sub-Saharan Africa, CIMMYT projects maize demand to double from 1995 levels by 2020—to 52 million tons. In this case, the grain will go directly to feed people, not livestock.

Although there is substantial international trade in maize, “for most developing countries, particularly those with large populations, the accelerating demand for maize must be met through dramatic increases in domestic supply,” note Pingali and Pandey.

And that poses some substantial challenges. Most poor countries won’t have the capital to pay for imports or to transport the grain to small communities where hunger is great. What all of this means, the researchers observe, is that ramping up production in the developing world will require “intensifying production on current maize land”—not finding new fields to put into production.

And that poses its own problems, Pingali and Pandey note. Today, yields in developing countries typically average around 3 tons per ha, or less than 40 percent of that on farms in the United States and other industrialized nations. The world record is 23.5 tons per ha achieved in 1985 by an Illinois farmer.

“The temperate plains of the United States provide some of the best growing conditions for corn in the world, making the U.S. the world’s top corn producer,” says the U.S. Grains Council in a recent report. Indeed, it notes, corn is the largest U.S. crop, both in volume of production and in revenues. Last year, for instance, U.S. farmers grew 42 percent of the world’s maize. According to the National Corn Growers Association, that amounted to some 256.9 million metric tons, or 10.1 billion bushels, as it’s traditionally measured domestically. That harvest was worth a whopping $23.6 billion to the U.S. economy.

However, CIMMYT notes, more than 90 percent of the yield in the United States and Europe comes from high-performing much-tinkered-with temperate strains. In contrast, 75 percent of maize produced in developing countries comes from non-temperate varieties. So, those strains developed to perform well in the U.S. Midwest can’t be expected to yield comparably in tropical, sub-tropical, or highland sites. CIMMYT is focusing its research to increase yields in varieties that flourish in these geographical areas—and within the economic constraints of the societies that will be sowing them.

With research money tight, international collaborative research programs like CIMMYT are setting priorities among their investments. In a report it issued a few years ago, the center recommended that sub-Saharan Africa and South Asia “should garner more research emphasis and investments than the other maize growing regions” because that’s where “we find the highest concentrations of poor [people] facing critical food security problems, while at the same time, alternative sources of technology supply are very limited.” In terms of ecological settings, CIMMYT recommends focusing research most heqavily on improving maize cultivars for lowland tropical sites.

So, as sweet corn season gets into full swing, consider the ubiquitous Zea mays—and how impressively big a nutritional and economic footprint this native American has stamped onto the global landscape.

Janet Raloff

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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