Conlee determined that both the jar and skeleton found at La Tiza date to the Middle Nasca period, from A.D. 450 to 550, but the artifacts were found in a cemetery from the Early Nasca period, from A.D. 1 to 450.
This placement suggests that the killing was an act of ancestral worship and that the sacrifice was meant to honor the forebears buried in the cemetery, Conlee said.
"This man may have been sacrificed in order to appease the ancestors of the community and therefore ensure continuation of life at the villages," she explained.
"This person was sacrificed during Middle Nasca, which was a time of great change," Conlee added. "It is known that throughout the Andes human sacrifice was performed in times of change to give gods an important gift to allow the people to continue."
The archaeologist also noted that the head jar is painted with the reversible image of a human face that can be seen right-side up or upside down, suggesting that the jar might have been meant as a substitute for the victim's missing head.
"The La Tiza head jar was a rather literal replacement and reflects the Nasca belief that a person needed to have a head when he entered the afterlife," Conlee said.
The jar also bears evidence of having been used before the burial. Conlee said that decorations on head jars suggest they were used for both human- and crop-fertility rituals.
"Head jars often have images of plants growing out of them, suggesting a direct link to agriculture fertility, as well as a desire to continue the fertility of the people in the community," she said.
Conlee reports her discovery in this month's issue of Current Anthropology.
John Verano, an expert in Nasca culture and archaeologist from Tulane University, praised the find.
(Verano is a grantee of the National Geographic Society's Committee for Research and Exploration. National Geographic News is a division of the National Geographic Society.)
"This is an unusual and well-documented discovery, as few headless Nasca skeletons are known," he said.
But Verano held out the possibility that the La Tiza victim may have been a casualty of war.
"One alternative explanation is that this might simply have been someone who had been killed and decapitated in a raid and whose body subsequently was recovered by relatives who gave it a proper burial, with a ceramic vessel replacing his lost head," he said.
"But it's a great find, whatever happened to this poor guy."
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