February 2003

From Texas A&M University

Agriculture's origin may be hidden in 'invisible' clues

COLLEGE STATION, Friday, February 14, 2003 As scientists attempt to learn about the origins of agriculture in the New World, they're focusing on what, for the most part, is invisible microscopic plant crystals, tiny starch grains and fossilized pollen.

These microscopic plant traces reliably record the earliest use of domesticated plants, says Texas A&M University anthropologist Vaughn Bryant, who is also the director the university's palynology laboratory.

Once thought to have begun in the upland regions of Mexico and South America, New World plant domestication through the examination of microscopic plant crystals called "phytoliths" has been linked to the lowland tropical regions in Central and South America, Bryant explains.

Within the last several years, fossilized pollen evidence from cultivated plants related to modern forms of maize was found in the Mexican state of Tabasco by a team of scientists, including Texas A&M anthropologist John G. Jones.

The evidence may be the earliest record of lowland maize cultivation and dates to around 5,100 calendar years BC about a thousand years earlier than previously believed, says Jones, a Texas A&M anthropologist specializing in archaeological pollen research.

Because the ancient maize pollen was found far from its native habitat, Jones says it represents proof that people who were already practicing a type of horticulture brought the seeds from the west and then planted them in fields near the Gulf of Mexico.

Such ancient "farmers," he says, would have selectively bred these plants over thousands of years until they produced the type of corn we use today with a rows of seeds on a cob.

Findings like those of Jones' and his team have not been common in archaeology. For more than half a century, Bryant says, people looked in the wrong places for the wrong types of evidence.

Because most plant remains such as leaves, wood, fibers, nuts and cobs quickly rot and disappear in the moist, oxidizing soils of many tropical lowland regions, Bryant says few archaeologists searched those regions. Instead, upland regions, he says, were favored because of their ease of access and previous successes, which ensured continued funding.

Despite this, some archaeologists did investigate lowland regions throughout the last several decades, searching for different types of clues. Scientists Dolores R. Piperno and Deborah M. Pearsall developed phytolith keys to a variety of plants while they pioneered the search for these microscopic clues, Bryant notes.

"There have always been some who have believed that the most logical system for early domestication would have been to use easy-to-grow root crops that do well in the tropical lowlands where they would need a minimum of tending the problem has been proving these ideas," Bryant notes.

That proof, he says, is now being found in the form of plant remains that were overlooked for years. Today, research has shown that pollen, starch grains, and phytoliths are reliable evidence that can be linked to the earliest domesticated plants, proving where and when agriculture began, Bryant explains.

Contact: Vaughn M. Bryant, 979-845-5255 or via email: vbryant@neo.tamu.edu or Ryan A. Garcia 979-845-4680 or via email: rag@univrel.tamu.edu.











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