Two climbers (one of them Reinhold Messner) with Otzi, Europe’s oldest natural human mummy, in the Otztal Alps between Austria and Italy in September 1991.
Credit: Paul Hanny/Gamma-Rapho/Getty Images
Two climbers (one of them Reinhold Messner) with Otzi, Europe’s oldest natural human mummy, 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 over 5,000 years. The chamber temperature is -6º C, with 99 percent humidity carefully maintained with 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 find that it was also the perfect environment for some of the microbes Ötzi carried down from the mountains.
In the samples taken from the mummy, Sarhan and his colleagues found four cold-resistant yeast strains closely related to similar yeasts found in Arctic glaciers, Antarctica, and the high mountains of Italy and Russia. And unlike Ötzi’s long-dead gut bacteria, which left behind freshly broken, aged fragments of DNA, the yeasts appear alive and multiplying (ahem, albeit at a glacial pace).
“These yeasts have accompanied Ötzi on his long journey for millennia,” Frank Maxiner, director of the Institute for Mummy Research at Eurac and co-author of the latest study, said in a press release. (Ötzi probably doesn’t find it very comforting, but you never know.)
Molten ancient microbes or long-lived colony?
Yeasts – species Phenolifera, Glaciozyme, Goffeauzymaand Marciafor mycology fans – turned into water sampled from Ötzi’s skin, stomach and insides. Sarhan and colleagues grew live yeast from the samples, but their shotgun metagenomic results also revealed many short DNA fragments, the kind of damage that occurs when DNA molecules break down over time. This is a sign of ancient DNA, meaning that yeast likely lived in Ötzi’s body shortly after his death.
When Sarhan and his colleagues compared samples taken in 2010 to samples taken in 2019, they saw longer fragments and less damage on average—in other words, there was more recent DNA in the mix, indicating that the yeast was growing slowly but steadily.
