Ancient Kernel: Clue to Origins of Farming?
In a Remote Cave, Archeologists Discover Earliest Sign Yet of Maize Agriculture in North America
By Patricia McBroom, Public Affairs
The kernel of domesticated corn or maize, Zea mays, dated at 3,690 years old, was excavated from McEuen Cave in the rugged Gila Mountains some 60 miles northeast of Tucson by M. Steven Shackley, a research archaeologist at the Phoebe Apperson Hearst Museum of Anthropology, and Bruce B. Huckell and Lisa Huckell, research archaeologists at the Maxwell Museum, University of New Mexico.
The discovery adds to a growing body of evidence that hunters and gatherers in the southwestern United States and northern Mexico turned to farming much earlier than had been thought, perhaps as early as 2,500 years ago, said Shackley. The findings are published in the current issue (winter) of the journal Archaeology Southwest.
"With this new evidence, we can make the case that maize spread rapidly throughout hunting and gathering groups almost as soon as it was introduced into the Southwest," said Shackley.
Until now, he said, "people have been dismissing these early dates as anomalous. But we're getting too many of them to ignore."
He said that conventional belief also holds that maize had little impact on Southwest Indians when it was first introduced and that it spread slowly throughout the region.
This newest evidence is the ninth discovery of a Southwestern maize sample that is older than 3,000 years. In addition, two to three of the maize specimens are pushing 4,000 years old, including the present one -- which could be as old as 4,150 years, said Shackley.
Dates for maize from the northern end of Mexico's Sierra Madre Mountains are of similar age to those found in the lowlands north of the border, Shackley said.
"This means there was fairly rapid communication between all these groups," he added.
The new dates for the first signs of maize also correspond with the recent discovery of a complex farming village, dated at some 3,000 years old, in the Tucson Basin.
"These recent discoveries at McEuen Cave and early settled agricultural village sites in the Tucson Basin have completely changed our conception of social evolution in this region," said Shackley.
"By 1,000 B.C., settled farming village communities already were established in southern and perhaps northern Arizona, inhabited by a people relying on maize agriculture rather than hunting and gathering."
The radiocarbon dating of the new sample used a relatively new technique that allows direct dating of the corn kernel itself rather than relying only on dating carbon in the surrounding matrix -- a technique, said Shackley, that is greatly expanding knowledge of the arrival of agriculture.
The maize was found at a depth of some three feet beneath the floor of the cave where two Middle Archaic dart points, dated 3,000 B.C. to 500 B.C., also were found. Other maize from the same area dated from about 2,800 years ago, indicating that an older deposit had washed into and been redeposited in the younger levels.
The archaeologists expect to do further excavation in the area to verify their findings.