Ötzi the Iceman’s little monsters are still growing

Two climbers (one of them Reinhold Messner) and Otzi, the oldest human woman 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, very close to the glacier that preserved his body for over 5,000 years. The room is strong -6º Celsius, with a humidity of 99% carefully maintained by spraying water with UV. This is enough to protect women from pathogens that contribute to the decomposition of human remains. But Sarhan and his friends were surprised to find that there is also a very good place for the small insects that Ötzi carried with him down the mountains.

In the woman’s samples, Sarhan and his colleagues found four types of cold-tolerant yeast, all of which are closely related to similar yeasts found on the ice slopes of the Arctic, Antarctica, and on the mountaintops of Italy and Russia. And unlike the long-dead bacteria in Ötzi’s gut, which left behind broken, old DNA fragments, the yeasts appear to be alive and reproducing (albeit at, ahem, glacial speeds).

“These leavens have accompanied Ötzi on his long journey over thousands of years,” said Frank Maxiner, director of the Institute for Mummy Studies at Eurac and co-author of the latest study, in a press release. (Otzi probably doesn’t get that comfort, but you never know.)

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Yeast—types of Phenolifera, Glaciozyme, Goffeauzymaand Markofor mycologists—they looked at Ötzi’s skin, his stomach, and the fluids taken from his body. Sarhan and his colleagues created live yeast from the samples, but their metagenomics shotgun results also revealed a bunch of small DNA fragments, which contain the damage that occurs when DNA molecules break down over time. That’s a sign of ancient DNA, which meant that the yeast had apparently been alive in Ötzi’s body since his death.

And when Sarhan and his colleagues compared the samples taken in 2010 with those taken in 2019, they saw long and slightly damaged fragments, on average – in other words, there was recent DNA in the mix, indicating that the yeast was growing slowly but continuously.