Scientists say they can tell what some people in South America ate as their normal diet 2,000 years ago, thanks to some mummies -- and their preserved hair.

Chemical analysis of their hair suggests these ancient individuals who lived in the southern coastal region of modern-day Peru, preserved since then as mummies, likely consumed maize, beans and marine animals and plants, the researchers say.

Newly developed techniques in bioarchaeology and biogeochemistry have revealed new information about 14 mummies excavated nearly a century ago, they report in the Journal of Archaeological Science.

"We can use hair to look at diet because, quite simply, we are what we eat," says research leader Kelly Knudson, an anthropology professor at Arizona State University's Center for Bioarchaeological Research.

The mummies were discovered in 1927 in two burial sites on the southern Pacific Ocean coast of Peru.

The mummies were buried with colorful dyed textiles of cotton and wool that have been closely studied by archaeologists.

"The textiles have been sent to museums all over the world," Knudson says. "But we don't actually know much about the people themselves."

To find out, they used hair samples, focusing on nitrogen and carbon isotope analysis of keratin in the samples to establish what the individuals ate during the final period of their lives.

Since human hair grows gradually, a half-inch of hair represents about 4 weeks in an individual's life, the scientists noted.

"By looking at how far the hair is from the scalp, we were able to look at what they were eating in particular weeks or months before they died," Knudson explains.

What they found was that the mummified individuals appear to have consumed a diet of primarily marine products, along with plants such as maize and beans, the researchers determined.

The constituents of a peoples' diet can show where they lived and if they traveled as well as yield clues about their daily lives by providing evidence of whether their foods were sourced from fishing, farming or hunting and gathering, they note.

The continuous consumption of marine products suggest the people of the Paracas coastal region of Peru were either geographically stable, the researchers say, or they were traveling inland from their coastal homelands they took marine products with them.

"What is exciting to me about this research is that we are using new scientific techniques to learn more about mummies that were excavated almost 100 years ago," says Knudson. "It is a great application of new science to older museum collections."

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