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Ancient tooth plaque shows a more varied diet in Peru

December 06, 2008|Thomas H. Maugh II | Maugh is a Times staff writer.

Early Peruvians appear to have had a more varied diet than previously believed, according to starch grains embedded in plaque on their teeth.

The findings, reported Tuesday in the Proceedings of the National Academy of Sciences, move back by more than 2,000 years the date that humans in the New World were eating beans and a local fruit known as pacay -- indicating that they were committed farmers far earlier than believed.

They also ate peanuts and domesticated squash.

The teeth in the study were discovered more than 20 years ago in distinctive roundhouses in the 1,500-foot-high Nanchoc Valley on the lower western slopes of the Andes.

Recent radiocarbon dates for objects found closely associated with the teeth show that they are 6,000 to 8,500 years old, archaeologist Tom Dillehay of Vanderbilt University reported in the new study.

Dillehay sent 39 human teeth, probably from six to eight individuals, to paleobotanist Dolores Piperno of the Smithsonian Tropical Research Institute in Panama for study.

Comparing the starch grains to her reference collection, she found that the early people -- whose identity is not clear -- were consuming squash, Phaseolus beans (either limas or common beans), peanuts and pacay. Because wild squash is extremely bitter, Piperno concluded that the people had domesticated the plant, losing the gene that causes the bitterness.

Comparing the samples against starch grains that had been boiled in the lab, Piperno also concluded that much of the food had been cooked before consumption.

The analysis of starch in plaque provides an important new way of examining early diets, she added, because the fruits and vegetables themselves degrade over time, making it difficult for archaeologists to find remains.


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