Two mountaineers (one of them Reinhold Messner) with Otzi, the oldest natural human mummy in Europe, in the Otztal Alps, between Austria and Italy, in September 1991.
Credit: Paul Hanny/Gamma-Rapho/Getty Images
Two mountaineers (one of them Reinhold Messner) with Otzi, the oldest natural human mummy in Europe, in the Otztal Alps, between Austria and Italy, in September 1991.
Credit: Paul Hanny/Gamma-Rapho/Getty Images
Ötzi is kept in carefully maintained conditions, as close as possible to the glacier that preserved his body for more than 5,000 years. The chamber is at -6º Celsius, with 99 percent humidity carefully maintained by a spray of UV-treated water. This is enough to protect the mummy from most of the microbes that normally help decompose human remains. But Sarhan and his colleagues were surprised to discover that it is also the perfect environment for some microbes that Ötzi brought with him from the mountains.
In samples from the mummy, Sarhan and his colleagues found four strains of cold-tolerant yeast, all closely related to similar yeasts found in Arctic glaciers, in Antarctica, and high in the mountains of Italy and Russia. And unlike Ötzi’s long-dead gut bacteria, which left behind aged and broken fragments of DNA, the yeasts appear to be alive and reproducing (albeit at, ahem, a glacial pace).
“These yeasts have accompanied Ötzi on his long journey through the millennia,” Frank Maxiner, director of the Eurac Institute for Mummy Studies and co-author of the recent study, said in a press release. (Ötzi may not find this very comforting, but you never know.)
Thawed ancient microbes or a long-lived colony?
Yeasts—species of fenolifera, Glaciozyme, goffeauzymaand markiaFor mycology fans, it appeared on Ötzi’s skin, in his stomach, and in water extracted from inside his body. Sarhan and his colleagues grew live yeast from the samples, but their metagenomics results also revealed a bunch of short DNA fragments, most with the kind of damage that occurs when DNA molecules break down over time. That’s a hallmark of ancient DNA, which meant that yeast had probably been living in Ötzi’s body since shortly after his death.
And when Sarhan and his colleagues compared samples taken in 2010 to those taken in 2019, they saw longer fragments and less damage, on average; In other words, there was more recent DNA in the mixture, suggesting that the yeasts were growing slowly but persistently.
