But after staying remarkably well-preserved for millennia, in the past decade many of the Chinchorro mummies have begun to rapidly degrade. To discover the cause, and a way to stop the deterioration, Chilean preservationists turned to a Harvard scientist with a record of solving mysteries around threatened cultural artifacts.
Nearly 120 Chinchorro mummies are housed in the collection of the University of Tarapacá’s archaeological museum in Arica, Chile. That’s where scientists saw that the mummies were starting to degrade at an alarming rate. In some cases, specimens were turning into black ooze.
“In the last 10 years, the process has accelerated,” said Marcela Sepulveda, a professor of archaeology in the anthropology department and the Archeometric Analysis and Research Laboratories at the University of Tarapacá, during a recent visit to Cambridge. “It is very important to get more information about what’s causing this and to get the university and national government to do what’s necessary to preserve the Chinchorro mummies for the future.”
What was eating the mummies? To help solve the mystery, Sepulveda called on experts in Europe and North America, including Ralph Mitchell, Gordon McKay Professor of Applied Biology Emeritus at Harvard School of Engineering and Applied Sciences (SEAS). Mitchell has used his knowledge of environmental microbiology to pinpoint the causes of decay in everything from historic manuscripts to the walls of King Tutankhamen’s tomb to the Apollo spacesuits.
“We knew the mummies were degrading but nobody understood why,” he said. “This kind of degradation has never been studied before. We wanted to answer two questions: What was causing it and what could we do to prevent further degradation?”
Preparing the mummies “was a complicated process that took time — and amazing knowledge,” Sepulveda said. The Chinchorro would first extract the brains and organs, then reconstruct the body with fiber, fill the skull cavity with straw or ash, and use reeds to sew it back together, connecting jaw to cranium. A stick kept the spine straight and tethered to the skull. The embalmer restored the skin in place — sometimes patching the corpse together using the skin of sea lions or other animals. Finally, the mummy was covered with a paste, the color of which archaeologists assign to different epochs in the more than 3,000 years of Chinchorro mummy-making: black made from manganese was used in the oldest, red made from ocher was employed in later examples, and brown mud was applied to the most recent finds.
