The Nasca civilization is perhaps best known for the drawings its people etched onto the desert floor in southwest Peru, a massive and mysterious body of simple and intricate works that span several hundred square miles.
Less well known is that the ancient society, which existed from about 1 to 800 A.D., also harbored the largest collection of human trophy heads in the Andes region of South America. These human skulls were often worn or used as decoration and differ from the shrunken heads of other civilizations.
But just where those trophy heads came from has been the subject of a decades-long debate in academic circles, with some suggesting they might have been taken from distant enemies in battle.
But a recent study finds that these trophy heads came from the same area as the local Nasca population, not from far-off places.
Using tooth enamel from trophy heads, researchers tested for a variety of isotopes that would tell them where these humans likely lived and what they ate. They then compared those findings with isotope data from bodies of individuals buried at Nasca sites. The findings show that both the trophy heads and the bodies came from the same region.
"The evidence helps us to understand that the majority of these trophy heads were not the product of long distance war expeditions," said Dr. Ryan Williams, a curator at the Field Museum and an author of the study.
It is also an important step in understanding one aspect of an ancient civilization that preceded the first Peruvian Empire, experts say. In these discoveries, scientists can begin to get a clearer picture of the development of civilizations.
The study, published in the Journal of Anthropological Archeology in December, was conducted by researchers at Arizona State University, the University of Illinois at Chicago, Indiana University Northwest and the Field Museum.
The trophy heads themselves were part of a collection of 18 heads that have been in the Field Museum's collection for about 80 years, first brought back from the Nasca Drainage area by anthropologist Alfred Louis Kroeber.
Williams said the project began two years ago as an effort to determine the origins of the trophy heads, which have remained remarkably preserved thanks to the extremely hot and dry climate of the Nasca Drainage. The trophy heads, some of which still have hair, will not be displayed as a part of any exhibit out of respect for the sanctity of human remains, he said.
Each skull has a hole drilled into its frontal lobe, where a cord was attached so the skull could be hung or worn as decoration. But the exact use and purpose of the trophy heads remain somewhat nebulous.
While the research offers convincing evidence that the heads did not come from far-flung places, it still does not rule out war as the source of the heads. They could have been collected from warring between populations living in the Nasca area.
The skulls may also be the product of agricultural fertility rituals or could have been associated with ancestor worship. Some of the earliest Nasca pottery, known for its distinctive and vibrant depictions, have trophy heads drawn onto pots and vases. Later pottery has more warlike images.
Based off research of the clay pottery and previous studies of the Nasca society, many researchers already suspected that the trophy heads came from within the community.
"We would have expected this result, but the study ... was a really nice verification of our suspicions," said Kevin Vaughn, associate professor of anthropology at Purdue University.
But what the research provides is a way to match those theories with hard evidence, experts say.
"Now we can directly assess some of the issues surrounding who some of these people were," Williams said. "We still have this rich artistic resource and now we can begin to look at the two pieces of the puzzle simultaneously."
© 2009, Chicago Tribune.
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Explore further: Discovery helps solve mystery of South American trophy heads