In 1925, the American anthropologist Alfred Louis Kroeber (1876-1960) discovered a series of ‘trophy heads’ at six different sites in the region on the southern coast of Peru at the heart of the Nazca civilization, which flourished from approximately the first to the eighth centuries AD. The lips of the heads were sewn together with cactus spines and all the heads featured a hole in the centre of the forehead through which a carrying rope was inserted. Their meaning has remained a myth, however, for the past 100 years. Were they war trophies? Were they the heads of venerated ancestors, which bore a religious significance and were used in rituals or offerings?

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.