The Natural History of Maize

Ruben G Mendoza. Encyclopedia of Food and Culture. Editor: Solomon H Katz. Volume 2. New York: Charles Scribner’s Sons, 2003.

Maize, also referred to as corn or Indian corn in the United States and Great Britain, respectively, is a cereal plant of the Gramineae family of grasses that today constitutes the most widely distributed food plant in the world. Accordingly, maize—from the Arawak mahiz—is grown in diverse regions and climates, from 58 degrees north latitude in Canada and Russia to 40 degrees south latitude in South America. Maize cultivation and processing are driven by the production of food and livestock feed, fermentation, and raw materials for industry.

Given its many uses, maize is likely to be found in over 1,000 products in a well-stocked U.S. supermarket. The specifics of maize production, reproduction, cultivation, processing, and consumption—its resiliency, mutability, as well as the intractability of cultural and botanical constraints—continue to provide science with insights into the past and possible future of the species. Not surprisingly, maize is the most studied plant species on the planet.

The Ethnobotany of Maize

Ethnobotany, the study of symbiotic relationships between human cultures and the plants on which they rely, is one of the many fields of study fueling investigations into the earliest domesticated maize and its subsequent global diffusion. Ethnobotanists, archaeologists, anthropologists, taxonomists, food and horticultural scientists, nutritionists, geneticists, biotechnicians, art historians, and many others are all trying to find answers to the numerous questions posed by the evolution and proliferation of maize. This diverse body of scientific sources provides information about the natural and cultural history of maize.

The Quintessential Maize Plant

Experts have established that modern maize evolved from teosinte (God’s corn), or Zea mays ssp. Mexicana, although some botanists continue to argue that it evolved from an early Mesoamerican maize variety called Chapalote. Even the timing of maize origins has been questioned. A review of the botanical characteristics of both maize and teosinte will distinguish them and provide some idea of how maize developed into the fully domesticated cultigen it is today.

According to plant geneticist John Doebley, maize (Zea mays L. ssp. mays) and the teosintes (Zea spp.) differ profoundly in terms of vegetative characteristics and “inflorescence architecture” (1996, p. 66). That is, differences are specific to the form of the plant and its reproductive architecture, including variation in the mode of development and arrangement of the flowers or blooms along the axis of the plant.

In this instance, the distinctions are most notable in the forms of the male tassel, or spikelet, that sprouts at the summit of the maize or teosinte stalk, as well as in the form and development of the female inflorescence or maize ear. Despite these distinctions, Doebley acknowledges that maize and the Mexican teosintes are essentially variants of the same biological species. As such, they form fully fertile hybrids and cross-pollinate; the inherent differences in chromosome structure and other genetic aspects between teosinte and maize are no greater than those observed among the diverse races of maize (p. 66). Experiments distinguishing genes of teosinte from maize have been replicated in recent years through the use of molecular analysis.

The characteristic reproductive pattern of maize is a very ancient and primitive one. Maize includes both male and female reproductive characteristics and constitutes an Andropogonoid grass that bears a spike-like axis or tassel on which flowers or blooms are attached and from which pollen is dispersed; it is a self-pollinating plant that disperses pollen from the tassels to the “style” or “silk” of the maize ears (female inflorescences), where it is absorbed in the reproductive process. Whereas each tassel contains some 25 million pollen grains, each female inflorescence or maize ear contains upwards of 1,000 ovules or potential kernels. Each pollinated silk is thereby transformed into an individual kernel of maize that grows to contain a single ovule necessary for the reproduction of the plant itself. Maize leaves track the sun’s light and absorb its energy; a field of maize is optimally designed for producing high yields from solar energy.

Maize Variation and Race

There are some twenty-five “primary” races of maize found in Mesoamerica, and none of these is pure. The proliferation of hybrid variants and recent advances in bioengineered or genetically modified varieties of maize has seemingly sealed the fate of this most ancient foodstuff. In fact, the global proliferation of genetically engineered foods is poised to completely displace or replace existing strains of the primary grain crops with biologically engineered substitutes.

The evolutionary history and inherent mutability of maize are so complex that scientists continue to debate and question the taxonomic identification of all the extant races of maize in both wild and domestic contexts. There is no agreement about the taxonomic names or numbers of races that may exist in any single world region. Since maize is so easily hybridized, the number of varieties far exceeds any other crop species on record. Botanical taxonomists have loosely grouped these varieties into some 300 races for the Western Hemisphere alone. Early textbook taxonomies, on the other hand, once identified only six races, including dent, flint, flour, sweet, pop, and waxy varieties. Of these, two dominate American commercial agriculture and include the Flint (Zea indurata) and Dent (Zea indentata) varieties. The nine major types cultivated in the United States include the Southwestern Semidents, Southwestern twelve-row, Pima-Papago, Great Plains Flints and Flours, Corn Belt Dents, Southeastern Flints, Southern Dents, Derived Southern Dents, and Northern Flints.

Of those races of maize indigenous to Mesoamerica, four main groups of maize have been identified. Their respective taxonomic classifications are based on the vegetative characteristics of the plant, characteristics of the spike or spikelet, characteristics of the cob, and the physiological, genetic, and cytological characteristics of the plants studied. These primary maize groups are (1) antique indigenous, (2) exotic pre-Columbian, (3) prehistorical mestiza, and the (4) not well-defined or modern races. To this latter category may be added the proliferation of genetically engineered strains.

The antique indigenous group consists of those races that originated in Mesoamerica with the primitive earliest races of maize. Variations within this group are thought to be evidence of multiple independent origins in diverse areas of Mesoamerica. The races specifically identified with this group include Palomero Toluqueño, Arrociclo Amarillo, Chapolote, and Nal-Tel.

Maize in the New World

The history of maize and its domestication may be traced back some 8,000 years. Maize spread across the length and breadth of the Americas, and subsequently to Europe, Africa, and Asia. Teosinte (Zea mexicana) has been linked with the earliest maize in Mesoamerica and was first harvested as early as 10,000 years ago.

The origins of maize begin on the Pacific slope of the modern Mexican states of Oaxaca, Tehuacán, and the Valley of Mexico. The earliest primitive corncobs discovered in Mesoamerica were obtained from specimens recovered within a cave near Oaxaca. From there maize diffused rapidly into Central America and then into South America by way of the eastern slopes of the Andes approximately 4,000 years ago. Guatemala may have served as the source or conduit for the adoption of the earliest strains of maize in Andean South America and Peru. In fact, the initial appearance of maize in Peru has been dated to 6070 B.C.E. Ecuador, Chile, and Argentina, with Andean Peru, form a likely corridor for the transmission of maize from Guatemalan sources into coastal valleys. Some nineteen races of maize from ten Latin American countries have been identified with the Classic period of 300 to 900 C.E. Six of these evidenced interactions between Mesoamerican and Peruvian societies from the most remote periods of pre-Columbian cultural development.

New World dispersals

Walton C. Galinat has traced the diffusion of maize into North America to a Northern Flint Pathway established by 700 C.E. in the Rio Grande valley. From there maize spread northward along both the eastern and western flanks of the Rocky Mountains, and eastward along major river courses—including those of the Arkansas, Mississippi, Platte, and Ohio Rivers—permitting its continued cultivation and dispersal eastward. By 1200 C.E., maize cultivation was established in upstate New York and New England. While the eight-rowed variety of maize was cultivated in the southeastern United States in pre-Columbian times, the Southern Dent Pathway accounts for the distributions of other varieties of maize after 1500 C.E., subsequent to Spanish contact in those regions. Ultimately, the hybrid vigor identified with the larger and more robust forms of maize can be traced back to the merging of the Northern Flint varieties with the Southern Dent varieties by U.S. farmers of the Midwest in the mid-nineteenth century. According to Galinat, this hybrid fusion can be characterized as having resulted in an “inadvertent evolutionary explosion” that ultimately transformed maize into a highly productive and important foodstuff.

Maize in the Old World

Even before the Wampanoag Indians presented the early Plymouth colonists with maize at the first Thanksgiving celebration in 1621, enabling this early English colony in present-day Massachusetts to survive, maize had already made its way back to the Old World and was rapidly being incorporated into the agricultural economies of sixteenth-and seventeenth-century Europe and the Middle East, the Balkans, Africa, India, and Asia. In fact, according to Sylvia Johnson, as early as the mid-sixteenth century, maize had been introduced to Europe, western Asia, Africa, and China. These early Old World encounters with maize were ambivalent toward the exotic grain then known as Turkish wheat, Turkish grain, Spanish wheat, or Indian corn. In fact, negative reactions to maize in the Old World largely focused on the belief that maize was less nourishing than extant European grain products such as the wheat, barley, or oat cereals used in the production of bread and related by-products.

Despite its considerable productivity in comparison with wheat, its shorter growing season, and its considerable adaptive potential to marginal environments, maize was initially seen as a foodstuff fit only for animals or the poorest of the peasantry, who ground it up with water and ate it as a finely ground mush or porridge. This came to be known as “polenta” to the peoples of northern Italy, which has since been incorporated into European and American cuisines. Beginning in Italy, a variety of toppings and additives, including cheese and pasta, have diversified the ingredients of this poor persons’ food and transformed it into an international favorite.

In China and Southeast Asia, maize is cultivated in rotation with other, more traditional crops like rice or millet, and sequential cropping (relay cropping) strategies permit a form of multiple-cropping that overlaps the life cycles of two or more crops. These methods made possible the generation of crop surpluses in Asia beyond those originally identified with the exclusive or traditional reliance on rice as a primary cultigen. In fact, maize is being used throughout Asia to supplement more traditional crops by extending the growing season and expanding production potentials throughout the year. In addition, the production of maize fodder and feed for livestock has fueled the adoption of maize agriculture throughout the developing countries of Asia and Africa. Maize provides the world’s most cost-effective and highest yield plant resource currently available for the production of livestock forage, fodder, and feed (Dowswell et al., 1996, pp. 27-28).

Old World dispersals

The cultural, economic, and political impacts of the European discovery of maize were evident in the ensuing population boom that followed its introduction into the Old World. After 1492, maize rapidly diffused into Europe, Africa, and Asia and was successful in large part because it did not directly compete with existing grain crops such as rice, wheat, oats, millet, and barley. Maize was also suited to cultivation in otherwise poor growing conditions related to topography, soils, climates, aridity, and elevation. Significantly, maize also prospers in exceptionally wet climates unsuited to wheat or relatively arid regions unsuited to rice cultivation. Moreover, maize has the additional advantage of rapid returns and twice the productive yield per unit of land of wheat.

The adoption of maize in Africa and China heralded a dramatic social and cultural transformation. Maize provided a level of food surplus that permitted the exponential growth of populations. Whereas in Europe maize was seen as a substandard cereal grain, fit only for feeding the poor and hungry and livestock, in many areas of Africa and Asia maize came to dominate the agricultural economies of many nation-states. The productivity and efficiency of maize horticulture and its low production and transportation costs made it a cheap food for slaves captured and held by European and Arabic slave traders. Maize made possible the efficient and economical transport and exchange of horrific numbers of sub-Saharan Africans destined for the markets of Europe, the Middle East, and the Americas.

The African Connection

Although it remains unclear who first introduced maize to Europe, Africa, and the Old World more generally, a number of scholars now argue that the Portuguese colonies of Africa served as the initial conduit to the diffusion of maize in that hemisphere. Jean Andrews claims that maize, beans, peppers, squash, and turkeys diffused into the Balkans, or southeastern Europe, by way of Portuguese Africa, India, and the Ottoman Empire in the period following the voyages of Columbus (1993, pp. 194-204). So profound was the impact of maize on the African economy that, like Mesoamerica, culture and society, subsistence and settlement, political economy and gender relations, and the respective cuisines and culinary technologies of each of these vast regions were rapidly transformed to accommodate the adoption of maize and those human diasporas with which it was associated. The unique maize-based cultural complex of agricultural practices, extensive settlement patterns, and storage, distribution, and food processing technologies identified with maize cultivation in fact fueled much of the transformation in question. In Africa’s Emerging Maize Revolution, Derek Byerlee and Carl Eicher acknowledge that the adoption of maize has been the primary engine driving the transformation of the African social, political, and economic landscape for the many societies that have been swept up in this new agricultural revolution.

More specifically, it is becoming increasingly evident that those agricultural practices identified with maize, such as swidden cultivation, extensive or shifting settlement patterns that are, in turn, identified with swidden systems, the processing of maize with basalt grinding slabs, the female domination of these labor-intensive food processing and storage traditions, and the emerging role of women in the maize-dominated marketplace have all played significant roles in the transformation of the African political economy. Moreover, given the fact that in many areas of Africa, much of the traditional African agricultural complex—centered on such crops as millet—has been displaced by maize has much to do with the changing face of African cuisine at the most fundamental level of analysis, and more generally, at the interface of cultural change and transformation.

Africans prepare a maize porridge—called kpekple in Ghana, bidia in Zaire, sadza in Zimbabwe, putu in Zululand,mealie in South Africa, and posho or ugali in East Africa—consumed by millions. Virtually no African country has remained untouched by the diffusion and exchange of maize, and the agricultural practices on the African continent range from the simple sowing of maize kernels along rivers and streams to the cultivation of maize in household gardens. While widespread, these traditional practices are primitive compared to the magnitude and intensity of agribusiness development and investment in commercially viable maize agricultural field systems.

Maize Procurement and Processing

Maize is seldom described outside of the so-called Mesoamerican triumvirate of maize, beans, and squash. Early Mesoamerican peoples planted these food crops together, often planting beans and squash adjacent to maize so as to provide the former plants stalks on which to extend their vines. Mesoamerican cuisine similarly combined the products of these plants in a culinary mix that reinforced and supplemented the otherwise niacin-poor composition of maize-dominant dietary practices. Without these supplements, or the lime processing inherent in the production of masa (maize flour) used in the production of tortillas and related foodstuffs, maize-dominant diets have the potential to result in the spread of the skin disease pellagra. Pellagra spread rapidly and in epidemic proportions throughout all the European and African countries that first adopted maize consumption without similarly adopting the critically important nixtamalización process necessary for the production of nixtamal or lime-treated masa. The source of the disease remained a medical mystery until it was studied in the context of maize consumption in the southern United States. It was ultimately determined that the niacin-deficient nature of maize-dominant diets played a key nutritional role in the onset of those symptoms identified with pellagra.

Traditional Maize Agricultural Systems

In Latin America, maize is the central foodstuff of the hearth and household. Because of the broad range of climates, soils, and topographic and hydrological conditions under which maize may be cultivated, diverse agricultural methods have evolved to accommodate its cultivation and processing. Maize environments in the Third World have been classified into four major types: tropical, subtropical, temperate, and highlands. As of 1996, tropical environments accounted for 90.6 million acres, or 45 percent of the total area under maize cultivation in developing countries; temperate environments accounted for 55.1 million acres, or 27 percent of the total; subtropical environments accounted for 42 million acres, or 21 percent of the total; and highland environments constituted 15.3 million acres, or 8 percent of the total area under maize cultivation in the developing world (Dowswell, Paliwal, and Cantrell, pp. 38-46).

In the tropical forests of Mexico and Central America, maize agriculture is predominantly associated with swidden (slash-and-burn or shifting) agricultural systems and the development of milpas (maize fields). Swidden cultivation entails the scoring or felling of trees and the subsequent torching of dry foliage and timber left in the wake of the clearance operation. Once the forest parcel has been cleared, dibble sticks are used to pierce the soil for the sowing of maize kernels in the charred timbers of the milpa. In contrast, in highland Guatemala maize is cultivated on the steepest of mountain slopes and under the most challenging topographical and hydrological conditions. In highland central Mexico, on the other hand, maize cultivation took the form of chinampas (floating gardens)—perhaps the most unique agricultural system devoted to maize—that rapidly evolved and proliferated in the Basin of Mexico in pre-Columbian times. In fact, chinampas were a fundamentally important aspect of agricultural development in the highly populated Basin in the precontact period from the thirteenth to sixteenth centuries C.E. Earlier forms of agricultural intensification associated with both chinampas and maize cultivation have similarly been identified with the ancient metropolis of Teotihuacan, Mexico. This ancient city, which contained a population of some 150,000 people within an area of just under 8.5 square miles, was sustained through such productive systems of agricultural intensification during the period from 100 to 650 C.E. The only remaining Mesoamerican examples of this form of agricultural intensification are found in Xochimilco, Mexico.

In essence, chinampas entailed the creation of new agricultural parcels of land built atop floating islands or enclosures created within the shallow margins of Lake Texcoco. Chinampas plantations were framed within long, narrow rectangular enclosures formed from willow branches staked into the depths of the shallow lake bed—part of a system of lakes identified with Lake Texcoco—that once dominated the Basin of Mexico. Earth and mud gathered from the shallow lake bottom were dumped into these enclosures and used to form the agriculturally viable portion of those chinampasthat were eventually anchored to the shallow lake bottom through the growth of those willow shoots and branches used to stake the plots. The recurring introduction of nutrients for maize grown atop chinampa parcels entailed the use of lake bottom mud, silt, vegetation, and excrement in an otherwise effective and ecologically sound practice. In this way, the Mexican Aztecs and their predecessors increased their ability to feed a rapidly growing Basin population by expanding the amount of cultivable lands devoted to maize and related crop systems. The area identified with the lakeside community of Xochimilco in the southern Basin of Mexico continues the practice of chinampa cultivation and floating gardens, and such parcels enable Mexican farmers to excel at the production of maize, beans, squash, flowers, and a variety of other Mesoamerican crops.

In the Maya lowlands and along the coastal margins of the Yucatan peninsula, the ancient Maya devoted considerable resources to the production of maize and related crops in raised or ridged field systems. These massive ridged field systems are among the largest and most extensive earthworks ever produced by the Maya or other societies of ancient America. Created within swamps, flooded bajos, or water-filled shallow limestone sinks or coastal estuaries, raised fields (or ridged islands or embankments) were formed into elongated, roughly rectangular agricultural parcels by piling soils or upcast scooped from drained areas immediately adjacent to the embankment or island. The overall appearance of such fields resembles massive waffle-like garden grids. These individual islands, however, were broad enough to accommodate the passage of a tractor-trailer rig. Pollen studies from these large earthen constructions have determined that, while maize was the major product of these systems, a variety of other Mesoamerican foodstuffs were also cultivated. In fact, the quantity of foods produced by such systems far exceeded the amount projected for swidden agricultural systems (once thought to be the predominant means by which food was grown in the tropical landscapes of the Maya heartland).

Whether produced by the indigenous systems of milpa or chinampa agriculture, maize cultivation in much of the Third World, and in more traditional contexts, has been dominated by the use of the “dibble stick” since pre-Columbian times. Consisting of a shaft of wood with a pointed tip used to pierce the soil for the sowing of maize kernels, the dibble stick has persisted for thousands of years and has been adopted by subsistence farmers throughout developing countries that have adopted maize agriculture. Nineteenth-century American maize farmers adopted both the cylindrical silo or “corn crib” and the “dibble stick” from American Indian prototypes (Fussell, p. 152). Improvements on the dibble stick developed in the 1850s ranged from the Randall and Jones Double Hand Planter to the long-lived “Stabber” or “Jobber.” Both of these variations “stab” the soil and simultaneously dispense maize kernels into the holes (Fussell, pp. 144-146). Such early efforts ultimately led to the evolution of the automated maize planters of today. Unlike commercial systems of mass production identified with the technology of maize planting and cultivation, the dibble stick has weathered the introduction of new techniques and continues to dominate more traditional, nontechnological farming practices around the world.

The Maize Harvest of the Machine Age

One need only travel to places like the state of Nebraska to realize that maize agriculture dominates the agricultural traditions of some societies. In fact, a drive through Nebraska during the growing season might leave some outsiders with the impression that it consists of a seamless, seemingly endless, and very dense field of maize. For the past two hundred years, farmers and agricultural scientists in such areas have developed a variety of means, technologies, and hybrids suitable for the continuing propagation of maize. In The Story of Corn (1992), Fussell summarizes the many agricultural technologies, cropping and harvesting methods, hybrids, commercial products, and cultural and religious values identified with maize agriculture in the Americas and other parts of the world.

Methods of harvesting of maize range from the hand culling of hybrid maize cobs from home gardens to towering high-tech combines or harvesting machines and tractors rigged—in the largest combines—to cull maize ears or cobs at the rate of twelve rows at a time and thousands of bushels per day. Even an older combine or harvester can harvest some 10,000 bushels of maize per day, yielding 150 to 200 bushels per acre. On the other hand, the maintenance and upkeep of such machines easily runs into the thousands of dollars per year, an amount likely to double or triple in the Third World. A new combine harvester can cost from $100,000 to $200,000 or more in the United States. Whereas subsistence farmers throughout much of the Third World continue to thresh maize by hand without specialized equipment or resources, this task is left to agribusiness giants and commercial agricultural concerns in industrialized nations.

An array of farm machinery patents for the harvesting and processing of maize appeared shortly after the industrialization of farms. The U.S. Patent Office Report of 1860 lists hundreds of patents for corn planters, cultivators, harvesters, cornhuskers, corn shellers, cornstalk cutters, corn-shock binders, cornstalk shocking machines, corn cleaners, seed drills, rotary harrows, smut machines, corn and cob crushers and mills, and seed drills (Fussell, p. 144). The advent of the canning industry in 1862 and the proliferation of new land-grant colleges devoted to science, agriculture, and industry helped fuel the industrialization and modernization of maize procurement, processing, storage, distribution, and hybridization. In time, the industrialized farming operations and agricultural cooperatives of the Corn Belt adopted many mechanized methods for harvesting and threshing maize. Soon thereafter the towering grain silos and high-rise grain elevators of the Midwest replaced the humble corncribs adopted from the North American Indians. Despite this, traditional household corncribs survived the onslaught of the Industrial Age, and survivals include the Mesoamerican cuezcomatl (thatch-roofed adobe brick granary), the crib-logged granaries of the Sierra Tarahumara Indians of northern Mexico, and the clay-lined maize grain silos of Africa. In each instance, subsistence farmers and agribusiness giants alike must take into account the difficulties of storing maize at optimal conditions and balance humidity, the moisture content of the kernels, and the potential for pest infestations.

The Future of Maize

Maize is processed into a dizzying array of consumer products ranging from corn on the cob and popcorn to cornstarch, corn oils, automotive fuels, such as ethanol and gasohol, and alcoholic beverages, including corn beer (chichi) and whiskey. In addition to the more than 1,000 maize-based products that one is likely to find in the local supermarket, the genetically modified by-products of maize are creating their own culinary diversity and potentials, pitfalls, controversies, and complications for the world of food production and biotech industries. Beyond the diversity inherent in the production and distribution of maize in the marketplace, the reality is that maize remains the most important agricultural crop for over 70 million farm families worldwide. Eighty percent of the world’s farmers who cultivate maize are in developing nations of the Third World. This reality, coupled with the “genetic erosion” of the crop, has prompted some to ask whether maize can be bred so as to assure the sustainable evolution of the crop (Sevilla, p. 221). If the lawsuits for patent infringements against farmers by agribusiness corporations and biotechnology firms for the unlicensed use of their patented hybrids are any indication, the potentials of genetic diversity and hybrid vigor once identified with maize may be constrained to ever fewer and increasingly more vulnerable hybrid offspring.