Domestication of Corn

Abstract

The problem of the origin of corn has intrigued botanists and other students of plants for more than four centuries. The plant was unknown in any part of the Old World before 1492, while in the New World it was the basic food plant of all pre-Columbian advanced cultures and civilizations, including the Inca of South America and the Maya and Aztec of Middle America (1). Although these facts point strongly to its American origin, some writers have continued to argue eloquently for an Old World origin. A living wild form of corn has never been discovered, despite the extensive searches for it which have been carried on in various parts of the hemisphere. The absence of a wild form has been conducive to speculation-sometimes reaching the point of acrimonious debate-about its probable nature. There has, however, been general agreement that modern corn is unique among the major cereals in its grain-bearing inflorescence (the ear), which is completely enclosed in modified leaf sheaths (the husks), the plant being thus rendered incapable of dispersing its seeds. How, then, did wild corn, which to survive in nature must have had a means of dispersal, differ from modern cultivated corn? Where did it grow? How did it evolve under domestication?These are some of the questions that comprise the corn problem.Close collaboration in recent years between archeologists and botanists has furnished at least partial answers to all of these questions, and has also contributed to solving the problem of the beginning of agriculture in America and The authors are, respectively, Fisher professor of natural history, Harvard University, Cambridge, Mass.; director of the Tehuacan Project, Robert S. Peabody Foundation for Archeology, Andover, Mass.; and research fellow, Bussey InstitutiOn, Harvard University. 538 the rise of prehistoric cultures and civilizations. The first substantial contribution of archeology to the solution of the corn problem was the finding of prehistoric vegetal material in Bat Cave in New Mexico, excavated by Herbert Dick, then a graduate student in the Peabody Museum of Harvard University, in two expeditions, in 1948 and 1950. Accumulated trash, garbage, and excrement in this cave contained cobs and other parts of corn at all levels, and these cobs and parts showed a distinct evolutionary sequence from the lower to the upper levels (2). At the bottom of the refuse, which was some 2 meters deep, Dick found tiny cobs, 2 to 3 centimeters long, which were dated by radiocarbon determinations of associated charcoal at about 3600 B.C. Anatomical studies of these cobs led to the conclusion that the early Bat Cave corn was both a popcorn (a type with small, hard kernels capable of exploding when exposed to heat) and a pod form (a type with kernels partly enclosed by floral bracts which botanists call glumes and the layman knows as chaff) (3). Because the Bat Cave corn was both a popcorn and a pod corn, Mangelsdorf undertook to produce a genetic reconstruction of the ancestral form of corn by crossing pod corn and popcorn and ...

First Direct AMS Dates on Early Maize From Tehuacán, Mexico

“…Of several cave sites in the Tehuacan Valley that have undergone extensive investigations (Mangelsdorf, MacNeish & Galinat, 1964, 1967, three appear to record the domestication of corn (see also Benz & Iltis, ms; Benz, 1987Benz, , 1988. These are Cueva San Marcos, Cueva Coxcatlan and Cueva Purron.…”

“…Strong evidence exists (see, eg, Mangelsdorf, 1974;Iltis,1983) that this event occurred in one geographic area and people carried the plants and technology to other parts of the world. Archaeological evidence (Mangelsdorf, MacNeish & Galinat, 1964, 1967 compellingly suggets that the earliest maize grew in the Tehuacan Valley of central Mexico. Until now, the botanical specimens representing the early evolution of corn, owing to their small size and great value to ethnobotany, have been dated only by association with radiocarbon-dated charcoal and other non-maize material in archaeological sites.…”

Genetic signals of origin, spread, and introgression in a large sample of maize landraces

“…Traditionally the realm of archeology and botany (1,2), the study of plant domestication has seen important contributions from genetics during the last two decades (3). Genetic data often provide evidence that is hard to obtain by other means, making it an invaluable complement to other lines of inquiry.…”

Early maize ( Zea mays L.) cultivation in Mexico: Dating sedimentary pollen records and its implications

“…1) that recovered maize macrofossils that radiocarbon assays on associated charcoal suggested were at least 7,000 years old (5). The significance of those macrofossils became controversial after direct dating during the 1980s by accelerator mass spectrometry (AMS) seemed to revise their age to no more than 5,500 years ago (6,7).…”