Thanks to a technique that had never been applied in archeology, researchers learned that the girl suffered from a lung infection before she died. Professor Angelique Corthals, a forensic anthropologist at John Jay College, and her colleagues at SUNY Stony Brook, used a technique called shotgun proteomics to analyze tissue proteins rather than the mummy’s DNA.
Known as the Maiden, the mummy was discovered in 1999, along with two younger children, a 7-year-old boy and a 6-year-old girl, who died with her, about 25 yards from the summit of Llullaillaco. The Maiden and the children had been offered as sacrifices to the earth goddess. Past research revealed that the children had been fattened up with maize and dried llama meat before the sacrifice. Their bodies were buried on the summit and were remarkably well preserved because of the area’s freezing temperatures, low humidity and the presence of natural disinfectants. The mummies are on display at the Museum of High Mountain Archeology in Salta, Argentina.
“I was working on preservation of the mummies to make sure they don’t decay and that they are available to museum-goers,” says Corthals. “Once we knew the mummies were stable, we started looking at their health status before they died.”
The 15-year-old girl had a large lesion on one leg, which indicated to Corthals that she might have been sick when she was buried. Researchers took lip swabs from the Maiden and the 7-year-old boy and samples from the boy’s bloodied clothes. They didn’t take samples from the 6-year-old mummy because they suspect it might have been struck by lightning, which could hinder test results.
Proteins found in the Maiden were compared against large databases of human genomes to determine the actual proteins in the samples. What Corthals discovered is that the mummy’s protein profile mirrored that of a person with a chronic respiratory infection. The boy did not have the disease or pathogenic bacteria.
“With the protein profile that we recovered, we knew that this person was actively fighting a chronic lung infection,” says Corthals, whose findings were published in the July issue of PLoS One.
The shotgun proteomics technique has been widely used in the field of medicine but Corthals was the first one to apply it to archeological research. It’s proved to be more accurate than DNA techniques. DNA samples can easily get contaminated by particles from the environment. Proteins are less susceptible to environmental contamination and, unlike DNA, they reveal what the body was producing at the time of her death.
“Now that we know shotgun proteomics works, that it works in archeological samples, we can work on other archeological samples that are challenging,” says Corthals. “I’d like to see if it could work on very old skeletal remains, as well as Egyptian mummies.”