The Domestication of Maize in America

Maize: a 9,000 Year Old Radical Experiment in Plant Domestication

Heirloom Varieties of Maize
Heirloom Varieties of Maize. David Q. Cavagnaro / Getty Images

Maize (Zea mays) is a plant of enormous modern-day economic importance as foodstuff and alternative energy source. Scholars agree that maize was domesticated from the plant teosinte (Zea mays spp. parviglumis) in central America at least as early 9,000 years ago. In the Americas, maize is called corn, somewhat confusingly for the rest of the English-speaking world, where 'corn' refers to the seeds of any grain, including barley, wheat or rye.

The process of maize domestication radically changed it from its origins. The seeds of wild teosinte are encased in hard shells and arranged on a spike with five to seven rows, a spike that shatters when the grain is ripe to disperse its seed. Modern maize has hundreds of exposed kernels attached to a cob which is completely covered by husks and so cannot reproduce on its own. The morphological change is among the most divergent of speciation known on the planet, and it is only recent genetic studies that have proven the connection.

The earliest undisputed domesticated maize cobs are from Guila Naquitz cave in Guerrero, Mexico, dated about 4280-4210 cal BC. The earliest starch grains from domesticated maize have been found in the Xihuatoxtla Shelter, in the Rio Balsas valley of Guerrero, dated to ~9,000 cal BP.

Theories of Maize Domestication

Scientists have put forward two main theories about the rise of maize. The teosinte model argues that maize is a genetic mutation direct from teosinte in the lowlands of Guatemala. The hybrid origin model states that maize originated in the Mexican highlands as a hybrid of diploid perennial teosinte and early-stage domesticated maize. Eubanks has suggested a parallel development within the Mesoamerican interaction sphere between lowland and highland. Recently starch grain evidence has been discovered in Panama suggesting the use of maize there by 7800-7000 cal BP, and the discovery of wild teosinte growing in the Balsas river region of Mexico has lent support to that model.

The Xihuatoxtla rockshelter in the Balsas river region reported in 2009 was discovered to contain domesticated maize starch granules in occupation levels dated to the Paleoindian period, more than 8990 cal BP. That suggests that maize may have been domesticated by hunter-gatherers thousands of years before it became a staple of people's diets.

The Spread of Maize

Eventually, maize spread out from Mexico, probably by the diffusion of seeds along trade networks rather than migration of people. It was used in the southwestern United States by about 3,200 years ago, and in the eastern United States beginning about 2,100 years ago. By 700 AD, maize was well established up into the Canadian shield.

DNA studies suggest that purposeful selection for various traits continued throughout this period, leading to the wide variety of species today. For example, 35 different races of maize have been identified in pre-Columbian Peru, including popcorns, flint varieties, and varieties for specific uses, such as chicha beer, textile dyes, and flour.

Agricultural Traditions

As maize was spread outside of its roots in central America, it became part of already existing agricultural traditions, such as the Eastern Agricultural complex, which included pumpkin (Cucurbita sp), chenopodium and sunflower (Helianthus).

The earliest direct-dated maize in the northeast is the 399–208 cal BC, in the Finger Lakes region of New York, at the Vinette site. Other early appearances are Meadowcroft Rockshelter

Archaeological Sites Important to Maize

Archaeological sites of importance to the discussion of maize domestication include

  • Central America:  Xihuatoxtla Shelter (Guerrero, Mexico), Guila Naquitz (Oaxaca, Mexico) and Coxcatlan Cave (Tehuacan, Mexico)
  • Southwest USA: Bat Cave (New Mexico), Gatecliff Shelter (Nevada)
  • Midwest USA: Newt Kash Hollow (Tennesee)
  • Northeast USA: Vinette (New York), Schultz (Michigan), Meadowcroft (Pennsylvania)

Some Recent Maize Studies

This glossary entry is a part of the Guide to Plant Domestications, and part of the Dictionary of Archaeology.

Ellwood EC, Scott MP, Lipe WD, Matson RG, and Jones JG. 2013. Stone-boiling maize with limestone: experimental results and implications for nutrition among SE Utah preceramic groups. Journal of Archaeological Science 40(1):35-44.

Freeman, Jacob. "Crop Specialization, Exchange and Robustness in a Semi-arid Environment." Human Ecology, John M. Anderies, Andrea Torvinen, et al., Volume 42, Issue 2, SpringerLink, January 29, 2014.

Gil AF, Villalba R, Ugan A, Cortegoso V, Neme G, Michieli CT, Novellino P, and Durán V. 2014. Isotopic evidence on human bone for declining maize consumption during the little ice age in central western Argentina. Journal of Archaeological Science 49(0):213-227.

Grimstead DN, Buck SM, Vierra BJ, and Benson LV. 2015. Another possible source of archeological maize found in Chaco Canyon, NM: The Tohatchi Flats area, NM, USA. Journal of Archaeological Science: Reports 3:181-187.

Haas J, Creamer W, Huamán Mesía L, Goldstein D, Reinhard KJ, and Vergel Rodríguez C. 2013. Evidence for maize (Zea mays) in the Late Archaic (3000-1800 B.C.) in the Norte Chico region of Peru. Proceedings of the National Academy of Sciences 110(13):4945-4949.

Hart JP, and Lovis WA. 2013. Reevaluating What We Know About the Histories of Maize in Northeastern North America: A Review of Current Evidence. Journal of Archaeological Research 21(2):175-216

Killion TW. 2013. Nonagricultural cultivation and social complexityCurrent Anthropology 54(5):596-606.

Matsuda, Masahiko. "Upland Farming Systems Coping with Uncertain Rainfall in the Central Dry Zone of Myanmar: How Stable is Indigenous Multiple Cropping Under Semi-Arid Conditions?" Human Ecology 41, ResearchGate, December 2013.

Reed PF, and Geib PR. 2013. Sedentism, Social Change, Warfare, and the Bow in the Ancient Pueblo Southwest. Evolutionary Anthropology: Issues, News, and Reviews 22(3):103-110.

Sánchez-Pérez S, Solleiro-Rebolledo E, Sedov S, de Tapia EM, Golyeva A, Prado B, and Ibarra-Morales E. 2013. The Black San Pablo Paleosol of the Teotihuacan Valley, Mexico: Pedogenesis, Fertility, and Use in Ancient Agricultural and Urban Systems. Geoarchaeology 28(3):249-267.

Shillito, Lisa-Marie. "Grains of truth or transparent blindfolds? A review of current debates in archaeological phytolith analysis." Vegetation History and Archaeobotany, Volume 22, Issue 1, SpringerLink, January 2013.

Thompson V, Gremillion K, and Pluckhahn T. 2013. Challenging the Evidence for Prehistoric Wetland Maize Agriculture at Fort Center, Florida. American Antiquity 78(1):181-193.

VanDerwarker A, Marcoux J, and Hollenbach K. 2013. Farming and Foraging at the Crossroads: The Consequences of Cherokee and European Interaction Through the Late Eighteenth Century. American Antiquity 78(1):68-88.

Warinner C, Garcia NR, and Tuross N. 2013. Maize, beans and the floral isotopic diversity of highland Oaxaca, Mexico. Journal of Archaeological Science 40(2):868-873.