( CNN ) As long as 7,000 years ago , the Chinchorro people who lived along the desert coast of what is now Chile and Peru were mummifying the bodies of those who died . 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 . The culprit ? 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 . Egypt dig unearths 3,600-year-old mummy . 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 . Egypt 's mummies get CT scans . 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 . Scan reveals 1,000-year-old mummified monk hidden in statue .
Scientists find that higher humidity levels cause microbes to flourish on the mummies ' skin . Score: 6