Inside the frozen body of “Oetzi the Iceman,” scientists found cold-surviving yeasts and confirmed they were actively growing. The team even reproduced the yeasts in a fridge and, after three months of trying, produced a “very, very good” sourdough loaf—alongs
For thousands of years, Oetzi the Iceman has sat sealed in ice at minus six degrees Celsius—silent, preserved, and largely untouched by time. Then a team studying his microbiome did what few people would expect from a frozen relic: they found yeast that could still be alive.
The discovery centers on Oetzi. the mummified man who was killed about 5. 300 years ago by an arrow in the back while he was strolling through the Alps on the border of Austria and Italy. His remains were found in 1991 by two German hikers in the northern Italian region of South Tyrol. and since then his body has been kept at the same temperature as his icy tomb—allowing scientists to study him in unusual detail.
The latest research, published in the Microbiome journal on Wednesday, comes from an Italy-based team. It found evidence that both ancient and modern microbial life remain active in the frozen body.
“What we didn’t expect to find was yeast,” lead study author Mohamed Sarhan of the Eurac Research institute in the Italian city of Bolzano told AFP.
Sarhan described the implications in more personal terms: “His body hosts living. metabolically capable organisms that are actively responding to their environment.” He said the cold-adapted yeasts are growing. while certain bacteria have colonized and persisted across Oetzi’s tissues for decades. In his view. the mummy has become “a living biological interface — a meeting point between the ancient world and the present. where microbes from 5. 000 years ago coexist with organisms that arrived last decade.”.
From there, the story turned from biology into bread.
The scientists reported discovering four different yeasts that can survive sub-zero temperatures in Oetzi’s guts. skin and the “brownish” water that melted off his body when it was partially unfrozen. They said such yeasts typically live in very cold conditions such as Antarctica. so they are believed to have entered Oetzi’s body sometime after he died.
Genetic analysis suggested the yeasts entered soon after death. Sarhan said the “DNA damage levels very comparable to the original microbes” in the Iceman’s guts pointed in that direction.
“These yeasts have accompanied Oetzi on his long journey through the millennia,” co-author Frank Maixner said in a statement.
To test whether the microbes could be revived beyond the freezer of history, the team reproduced the gut yeast in a fridge. Sarhan described the obvious question anyone would ask: “If you tell anyone you have yeast, they immediately ask: can we use it for bread?”
They tried to make a sourdough loaf. “Initially it didn’t work,” Sarhan said. But after three months of effort, the experiment finally landed. “After three months of effort ‘we had a very, very good sourdough,’ Sarhan said with a laugh.”
When asked whether the scientists were considering using the yeast to brew beer, he replied, “It’s on the list.”
That “living ecosystem” framing is not just a curiosity—it also shaped how researchers see potential uses.
When Oetzi was discovered in 1991, he was initially treated as a normal cadaver. A chemical called phenol was used to stop fungus from growing in the body. The scientists said the unusual yeast was able to eat the phenol. In their telling, that could help break down the chemical in contaminated environments in the future.
The yeast wasn’t the only surprise in the ancient microbiome. The analysis also identified a particular kind of gut bacteria that is almost non-existent among modern humans. Sarhan said the bacteria has been detected among tribes in Africa and South America.
The team tied their findings to scarce comparisons. Sarhan explained that Oetzi and Bronze Age salt miners ate more fiber and whole grain than modern-day people. He said the other major window into ancient human microbiome comes from 3. 000-year-old feces preserved in a salt mine in Hallstatt. Austria.
The study in Microbiome said it “reveals that the Iceman is not a biologically ‘frozen’ time-capsule but rather a complex ecosystem.”
The timeline of Oetzi’s life helps explain why these microbes matter to scientists now. Previous research described his last meals as including deer and goat meat as well as wheat. Other work showed he was about age 45 when he died and was in good physical condition. carrying a copper ax. longbow. arrows and quiver and dagger. A separate 2023 finding concluded he was mostly descended from farmers from present-day Turkey. and that his head was balder and skin darker than what was initially thought.
An important question remains: are these yeasts truly thriving all along, or were they simply able to survive and later appear active under laboratory conditions? Sarhan said it is too early to say whether the yeast is harming the mummy, calling for more research.
Outside experts urged caution about the timeline of microbial growth. Nikolay Oskolkov. a researcher at the Latvian Institute of Organic Synthesis not involved in the study. told AFP it was interesting that “the Iceman’s microbiome is not ‘frozen’.” But he also warned that yeast samples were only taken in 2010 and 2019. providing “very little evidence that the yeasts have been multiplying over millennia. ” adding that he believed they were “relatively recent colonists of the mummy’s body.”.
Still, even that skepticism doesn’t erase the shock of the result: yeast from a man who died in the Ötztal Alps thousands of years ago can survive at sub-zero temperatures long enough for scientists to grow it again—and turn it into something warm, alive, and briefly shared with modern life.
Ötzi the Iceman Microbiome journal ancient yeast sourdough microbiome phenol cold-adapted microbes mummified remains