But, after millennia in which the mummies have remained well preserved, those ancient remains are now in danger of rapid decomposition, Harvard scientists have warned.
According to the Harvard School of Engineering and Applied Sciences, in a news report published Monday, rising humidity that helps microbes flourish on the mummies' skin is to blame.
As a result, scientists at the University of Tarapaca's archeological museum in Arica, northern Chile, have already seen some of its 120 prized examples of Chinchorro mummies start turning into a "black ooze," it said.
The role of rising humidity was confirmed through testing on skin samples by Harvard professor Ralph Mitchell and researcher Alice DeAraujo, according to the news release.
Their findings will help conservationists in Arica -- an arid area where humidity levels have been increasing in recent years -- safeguard their precious relics.
But Mitchell said he was concerned about potentially hundreds more mummies buried just below the sandy surface in the valleys of northern Chile.
"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 is quoted as saying.
A "complicated process" was used to prepare the mummies, said Marcela Sepulveda, professor of archaeology at the University of Tarapaca, cited in the news release.
It involved removing the brain and organs, replacing them with natural fiber and ash, stitching the body back up with reeds and covering the skin with a paste of manganese, ocher or brown mud, depending on the period.
The Chinchorro people mummified human remains for more than 3,000 years. The oldest of the mummies date back some 2,000 years before the ancient Egyptians mummified their pharaohs.