News

Mummy Mystery

Scientists say they know why the world’s oldest mummies have been turning to goo

March 11, 2015
BERNARDO ARRIAZA—UNIVERSITY OF TARAPACA/DPA/ZUMAPRESS.COM

Scientists believe the Chinchorro people began mummifying their dead around 2,000 years before the Egyptians.

Something strange has been happening at the University of Tarapacá’s archeological museum in Chile. Over the past several years, the museum’s famous Chinchorro mummies have been decaying at an alarming rate. In some cases, parts of the 7,000-year-old mummies have even turned into black ooze. 

Two years ago, scientists at Harvard began studying the mummies to figure out what was going on. “We wanted to answer two questions,” scientist Ralph Mitchell said in a press release. “What was causing it and what could we do to prevent further degradation?”

After months of testing mummy skin in the lab, Mitchell and his team believe they have solved the mystery. They say that extra humidity is to blame. The wetter weather allows tiny living things called microbes to thrive. And microbes are eating away at the mummies.

Scientists at Work

Chinchorro mummies are buried just beneath the sand in the valleys of northern Chile.

COURTESY MARCELA SEPULVEDA
Chinchorro mummies are buried just beneath the sand in the valleys of northern Chile.

In the lab, the scientists exposed pig skin and then mummy skin to very moist air. After 21 days in the extra humid environment, both skin samples began to break down. “The water activates the microbes,” Mitchell told TFK.

So, what do moist conditions in a lab have to do with the mummies’ home in the museum? The mummies are from a group of people called the Chinchorro, who lived along the coastal region between modern-day Peru and Chile, close to the Atacama Desert. The Atacama Desert is one of the driest places on Earth. The dry air has helped to preserve the mummies for thousands of years.

But experts say the area, which is also where the museum is located, has recently become extra humid due to climate change. In order to prevent the mummies from continuing to rot, Mitchell’s team says the humidity in the museum must be kept between 40 and 60 percent. 

With this mummy mystery solved, Mitchell can lend his experience to other problems. He says climate change could cause harm to other ancient objects. “Is climate change making important artifacts vulnerable? The answer is yes,” he says. 


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