The Chinchorro people who lived on the coast of modern-day Chile and Peru were the first to master mummification, a full 2000 years before the Egyptians. As far back as 5050 BCE, the Chinchorro were mummifying their their dead; not just elites but all members of their society.

After remaining well preserved for a much as 7,000 years many of the mummies have begun to rapidly degrade over the last decade.

Scientists at the Tarapacá’s archeological museum in Arica, Chile which houses 120 of the mummies were the first to notice the deterioration.

“In the last ten years, the process has accelerated. 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,” said 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, during a recent visit to Cambridge according to Phys.org.

Sepulvita sent out a call for helot researchers in North America and Europe.

Ralph Mitchell, Professor of Applied Biology, Emeritus at Harvard School of Engineering and Applied Sciences (SEAS), was one of the first to answer. Mitchell specializes in microbiology and specifically microbiology that leads to decay. Mitchell as previously been called on to examine decomposition on everything from historic manuscripts and the walls of King Tutankhamen’s tomb to the Apollo space suits.

“We knew the mummies were degrading but nobody understood why. 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,” said Mitchell.

The Chinchooro mummification method involved the extraction of brains and organs. Next the body was reconstructed with fiber and the skull cavity was stuff, generally with straw or ash. Reeds were then used to sew the body back together. A stick was used to keep the spine straight and then the skin was restored to its proper place. Finally the body was covered with paste, which varied by type over time.

After being supplied with samples of both degrading and undamaged skin, Mitchell and Alice DeAraujo, a research fellow in Mitchell’s lab went to work. They quickly determined that the cause was microbial and wondered if it was the microbiome on the skin itself that was responsible.

“The key word that we use a lot in microbiology is opportunism. With many diseases we encounter, the microbe is in our body to begin with, but when the environment changes it becomes an opportunist,” said Mitchell.

The researchers collected samples of the microbes present on the skin and tested them on samples of pig skin at varying levels of humidity. They determined that after 21 says at high humidity the pig skin began to degrade and then repeated the results on samples of mummy skin that had not begun to deteriorate.

They team rapidly determined that it was increased and sustained humidity levels that were causing the deterioration. The finding was consistent with Sepulveda’s report that humidity levels in Arica had been on the rise in recent years.

Analysis by DeAraujo determined that the ideal humidity range for storage of the mummies was 40 to 60 percent. At levels above 60 percent the degradation of the mummy began.

The team is now doing further analysis to test the potential impact of heat and light.

The results to date will help museum staff in Arica to preserve their collection. Sadly, the climate is changing and little can be done to preserve mummies still buried in the region.

Mitchell, however, has not given up.

“What about all of the artifacts out in the field? 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? You have these bodies out there and you’re asking the question: How do I stop them from decomposing? It’s almost a forensic problem,” he said.