The Llullaillaco Maiden is one of three mummies of young Incans who were sacrificed 500 years ago after being given drugs and alcohol. (Copyright Johan Reinhard)

More than 500 years ago, three children climbed the Llullaillaco volcano in Argentina and never came down, the probable victims of human sacrifice. Their bodies — naturally mummified in the cold, dry mountain air — have been studied by scientists since they were discovered, sitting in shrines, in 1999. Now new evidence shows that coca and alcohol might have played a more-than-ceremonial role in their deaths.

The children — a boy and girl about 4 or 5 years old and a girl whom archaeologists call the Llullaillaco Maiden, who was about 13 —were part of an Incan ritual known as capacocha, in which children were killed or left to die of exposure.

Most of what scientists know about the lives of the Llullaillaco mummies comes from their hair, which absorbs materials circulating in the bloodstream. In 2007, scientists analyzed the carbon and nitrogen isotopes found in the Maiden’s long, tightly braided locks and learned that about a year before she died, she went from eating mostly potatoes to consuming more animal protein and maize.

In a study reported last week in the Proceedings of the National Academy of Sciences, scientists measured the levels of a few key metabolites in the Maiden’s hair and saw that her consumption of coca and alcohol began to increase around the same time that her diet changed. Her coca use peaked about six months before she died, while her alcohol consumption skyrocketed in her final weeks. The boy and the girl, both of whom had shorter, less-kempt hair, also ingested the two drugs but in much smaller amounts than the Maiden.

“We’re starting to see a picture . . . of an emerging sequence of events that culminated in [the Maiden’s] sacrifice,” says Andrew Wilson, an archaeologist at Britain’s University of Bradford, who led both the 2007 research project and the new study. He suspects that her initial change in diet and drug consumption probably coincided with her selection as an aclla, or “ chosen woman.” In Incan culture, these women were “selected to live apart from their families at around the age of puberty, probably under the guardianship of priestesses,” he explains. Acllas were trained to produce chicha, a fermented maize drink that was probably the Maiden’s principal source of alcohol. Meanwhile, coca was a “revered” ritual substance, Wilson explains.

Although historical sources report that being selected as a capacocha sacrifice was considered an honor, Wilson wonders if the alcohol may have been used to sedate the Maiden in the weeks leading up to her death. What’s more, alcohol impairs the shivering reflex, so if she was left to die of exposure, drinking might have hastened her death. But the presence of coca complicates that picture somewhat, because it can slightly increase body temperature by causing the blood vessels to constrict.

Wilson suspects that the Maiden, at least, was probably heavily sedated, placed in the shrine and left to die. While other high-altitude Incan mummies show signs of head trauma, the Llullaillaco trio appear to have died peacefully. There were “no outward signs of fear,” such as vomiting or defecation in the Maiden’s shrine, Wilson says, and the fact that she was found sitting in a cross-legged position surrounded by intact offerings suggests that she didn’t struggle.

Still, it’s possible that her body was arranged in that position just after death, implying that a more deliberate act, like suffocation or poisoning, might have taken her life before the harsh environment of the mountain had a chance to do its work.

ScienceNow , the daily online news service of the journal Science