Scientists believe climate change is turning a treasure-trove of exceptionally well-preserved Chilean mummies into "black ooze" at an alarming rate.
The hunter-gatherer Chinchorro people, who lived along the coast of modern-day Chile and Peru, were mummifying members of their community at least two thousand years before the ancient Egyptians started to preserve the bodies of their pharaohs, the Harvard School of Engineering and Applied Sciences (SEAS) reported. The ancient people did not only reserve the preservation method for their elite, but mummified people from all walks of life, and even unborn fetuses. Radiocarbon dating has shown these mummies were being embalmed as far back as 5050 B.C. After remaining pristine for millennia, these mummies have mysteriously started to rapidly deteriorate over the past decade.
"In the last ten years, the process has accelerated," Marcela Sepulveda, professor of archaeology in the anthropology department and Archeometric Analysis and Research Laboratories at the University of Tarapacá who specializes in materials characterization, said 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."
To help discover what was causing the dramatic deterioration, researchers compared degraded and undamaged skins samples from mummies held at the University of Tarapacá's archaeological museum in Arica, Chile. The scientists quickly determined that the cause of the deterioration was microbial, and set out to find the culprit.
"The key word that we use a lot in microbiology is opportunism," said Ralph Mitchell Gordon McKay, professor emeritus of applied biology at SEAS. "With many diseases we encounter, the microbe is in our body to begin with, but when the environment changes it becomes an opportunist."
Sepulveda and Mitchell isolate microbes from both sets of skin samples, cultured the microbes in a lab and exposed them to varying levels of humidity; they also monitored the degradation rate of pigskin when exposed to different humidity levels. They found the pigskin started to degrade after 21 days of exposure to high humidity, and the mummy skin also decomposed more rapidly at higher humidity levels.
This finding lined up with the fact that humidity levels in Arica have been on the rise. The pair determined the ideal condition for the mummies to be stored at was between 40 and 60 percent humidity. The team is now working to help the museum staff fine-tune humidity and light levels in hopes of putting a stop to the rapid decomposition.
These findings could help preserve the mummies that are already stored in museums, but the solution isn't as easy for specimens still buried in the field waiting to be discovered.
"How do you preserve them outside the museum? Is there a scientific answer to protect these important historic objects from the devastating effects of climate change?" Mitchell asked.
The work was supported by Harvard SEAS, Consejo Nacional de Investigación Científica y Tecnológica in Chile and the Universidad de Tarapacá.
