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Posted 06.26.06

Plant particles found on stone tools give insight to early human life

COLUMBIA, Mo. -- The food that early people ate can serve as a clue to how they lived. A University of Missouri-Columbia researcher and her colleagues have discovered a new approach for identifying important root and tuber crops in the New World, which until now has been very difficult.

"Roots and tubers are dietary staples in many parts of the world; however, their use is difficult to document archaeologically because their organic remains are often poorly preserved in archeological sediments," said Deborah Pearsall, professor of anthropology and associate director of American archaeology at MU.

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Economic Botany

Pearsall and MU graduate Karol Chandler-Ezell, director of the anthropology program at Stephen F. Austin State University and lead author of the study, discovered that the roots and tubers of several important New World food plants produce phytoliths, which are microscopic silica bodies that occur in plants. Phytoliths not only identify the plant used, but also substantiate the fact that roots and tubers were consumed in the past.

"Often in archeology, all we can say is that the remains of a certain plant were found at an archeological site; we can't say definitely how the plant was used or what part of it was used. These are severe limitations to understanding diet. Our discovery makes this task easier," Pearsall said.

This discovery helped researchers learn that people living on the coast of Ecuador 4,500 years ago (around 2500 BC) were farmers who not only grew maize, but also root and tuber crops including manioc. Pearsall said the discovery proves that farming during that time period was already very advanced. Manioc is native to eastern South America and must have been carried or traded far from its home to appear in coastal Ecuador on the western coast of South America. It was during that time period that the Real Alto site grew to its largest size and was a ceremonial center.

"These phytoliths and starch residues provide evidence that both raw and cooked foods were processed in this early mixed agricultural economy," Pearsall said. "This research is particularly relevant for documenting the origins and spread of economically important root and tuber crops, which were a large part of the daily diet of prehistoric peoples in the tropics."

According to Pearsall, this knowledge about the prehistory of Ecuador gives archaeologists new insight into the functioning of the society at that time. Societies that are agricultural have different characteristics than those where people hunt, fish and gather food.

The study is featured on the cover of the summer issue of Economic Botany. The study, which also included the participation of James A. Zeidler, one of the excavators of Real Alto, was funded by the University of Missouri Research Board.



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