July 29, 2013 at 3:04 PM ET
Three Inca children found mummified atop a 20,000-foot volcano in South America consumed increasing amounts of coca leaf and corn beer for up to a year before they were sacrificed, according to a new study.
Sedation by the plant and alcohol combined with the frigid, high-altitude setting may explain how the children were killed. There is no evidence for direct violence, the researchers noted.
The coca leaf and corn beer consumption rises about six months before death and then skyrockets in the final weeks, especially for the eldest, a 13-year-old girl known as the "Ice Maiden."
"She was probably heavily sedated by the point at which she succumbs to death," Andrew Wilson, an archaeologist at the University of Bradford in the United Kingdom and the study's lead author, told NBC News.
The finding is based on detailed analyses of hair taken from the more than 500-year-old mummified remains, which also include a four-year-old girl and a five-year-old boy. The boy and girl were perhaps the maiden's attendants.
The data corroborate earlier research showing the children ate more meat and corn in their final year. Taken together, the studies suggest the peasant children were selected for the ritual sacrifice and lived a high-status life until their death near the top of the Llullaillacao Volcano in Argentina, Wilson said.
He and colleagues present the new analysis in a paper published Monday in the Proceedings of the National Academy of Sciences.
Far from the mountain
The corn beer chicha and coca leaf, the plant that contains cocaine, are prominent features of Andean culture, so finding their signature "is not a surprise in itself," John Verano, an anthropologist at Tulane University in New Orleans who was not involved in the new study, told NBC News.
"But it is particularly interesting the level of detail at which (the researchers) are able to look at it," he added. "It allows them to hypothesize why the older child of the three was drinking so much chicha in her last month of life and what that might have indicated about her lifestyle and activities."
According to Wilson, the story likely begins "far from the mountain" in the Inca capital of Cusco, Peru, where the Ice Maiden was taken to live "under the guardianship of priestesses" and passed her time weaving textiles and brewing chicha.
At about six months before death, there was a ceremony that involved ritual hair cutting — some clippings were found with the mummies — and that coincides with a peak in coca consumption.
The coca consumption and alcohol use then begin to rise sharply again in the weeks before death, probably as the Ice Maiden and two younger children were marched from Cusco to the volcano, stopping along the way for ceremonies that likely involved large amounts of coca and chicha.
The researchers suspect the Inca rulers wanted the sacrifice to be known throughout the empire, which was expanding southward at the time of the mummies' death. The Llullaillacao Volcano is at the empire's southern extent.
"It is something that is designed to create this climate of fear and to basically help build … new allegiances," Wilson said.
These festivals en route to the mountain, Verano noted, could explain why the Ice Maiden was drinking so much corn beer along with elevated coca chewing in her final weeks.
It's also possible, he added, that "she had a drinking problem. Maybe she started drinking beer the last year of her life and just found it to be pleasant or particularly soothing."
The mummies were discovered in 1999 and are considered among the best preserved mummies from anywhere in the world.
The Ice Maiden was inside a tomb structure, surrounded by offerings from the four corners of the Inca empire such as seashells, bird feathers, coca and corn. Her head is bowed as if she fell asleep, sedated, and succumbed to the biting cold and thin air as is inevitable at such altitude.
The levels of alcohol and coca are higher for the older girl, a finding that may "support the idea of her being calmed intentionally," Verano said. "It could be that she had a better idea of what was going to happen to her. She was older."
The data, he added, allows researchers to better imagine the lives of these children, but noted that their story is one of interpretation. There are no eyewitness accounts.
"For me," Wilson said, "it really does send somewhat of a shiver down my spine … It is almost the children being able to speak to us directly through some of this data, some of the things they experienced."
John Roach is a contributing writer for NBC News. To learn more about him, visit his website.