Recent research has, however, revealed the geographical origins of the trophy heads, providing new clues as to their significance. Archaeologists compared strontium, oxygen, and carbon isotope data found in the tooth enamel of 16 of the trophy heads, originally discovered in 1925 and currently held at the Chicago Field Museum of Natural History, with that from 13 mummified bodies buried in the Nazca region. The atomic structures of strontium, oxygen, and carbon vary by geographical location, thus reflecting where the person lived and his or her diet.
The results of the study, published online on December 11th in the Journal of Anthropological Archaeology, concluded that the trophy heads did not come from a distinct geographical region and that the individuals in the study consumed similar diets. The trophy heads came from the local Nazca population, rather than from a neighbouring enemy civilisation, thus hinting that they may have been used in rituals. Widespread depictions of trophy heads on painted pottery from the late Nazca period suggest that collecting and displaying trophy heads was a relatively common practice amongst the Nazca civilisation.
Nevertheless, researchers do not rule out that the heads may have also served as war trophies. Paintings on pottery often reveal warriors holding trophy heads, which may have come from warring in the Nazca area. Considering the extensive lifespan of the Nazca culture over more than seven centuries, it also seems likely that the role and purpose of trophy heads evolved over time.
In the words of Professor Kelly Knudson, the lead author of the study from Arizona State University:
Italian Archaeologist Giuseppe Orefici, who has worked since 1982 excavating the ancient Nazca ceremonial city of Cahuachi, approximately 28 kilometres away from the modern city of Nazca, explained how: