Researchers have uncovered that yeast has been thriving within the gastrointestinal tract of the ancient mummy known as Oetzi the Iceman for thousands of years, leading them to create sourdough bread using these microorganisms. Oetzi, who lived over 5,300 years ago, met his demise in the Alps near the border of Austria and Italy, where he was struck by an arrow.
His remains were discovered in 1991 by two hikers in South Tyrol, Italy, where he had been preserved in ice since his death. The consistently low temperature of minus six degrees Celsius has allowed scientists to conduct extensive studies on Oetzi, providing a unique glimpse into early human existence.
A recent study published in the journal Microbiome on Wednesday by a research team based in Italy revealed that both ancient and contemporary microbial life continues to thrive in Oetzi’s frozen body. Mohamed Sarhan, the lead author from the Eurac Research Institute in Bolzano, noted that the presence of yeast was an unexpected find. He explained that Oetzi’s body contains living organisms that are actively interacting with their environment, highlighting that cold-adapted yeasts and certain bacteria have survived in his tissues for decades.
Researchers identified four distinct types of yeasts capable of enduring sub-zero temperatures, found in Oetzi’s gut, skin, and the brownish water that melted from his body during partial thawing. These yeasts are typically found in extremely cold environments like Antarctica, suggesting they may have entered Oetzi’s system post-mortem. Genetic analysis indicated that the DNA damage levels in the yeasts were similar to those of the original microbes, implying they colonized his body soon after his death.
Study co-author Frank Maixner remarked that these yeasts have been part of Oetzi’s journey through time. The researchers successfully cultivated the gut yeast in a refrigerator, and after several months of experimentation, they managed to produce a satisfactory sourdough loaf. Sarhan humorously noted that the scientists are also considering brewing beer with the yeast in the future.
The implications of this yeast discovery extend beyond culinary endeavors. When Oetzi was first found in 1991, his body was treated with phenol to inhibit fungal growth. Interestingly, the yeast was capable of metabolizing phenol, suggesting potential applications for bioremediation in contaminated sites.
In addition to the yeast, Oetzi’s microbiome analysis revealed a distinct type of gut bacteria that has become nearly extinct in modern humans, though it still exists among certain tribes in Africa and South America. This bacteria has also been identified in 3,000-year-old fecal matter preserved in a salt mine in Hallstatt, Austria, providing one of the few insights into the ancient human microbiome.
According to Sarhan, both Oetzi and the Bronze Age salt miners consumed more fiber and whole grains than people today. The study concluded that Oetzi represents not a static biological time capsule but rather a dynamic ecosystem. Previous findings indicated that Oetzi’s last meals consisted of deer and goat meat, as well as wheat. He was approximately 45 years old at the time of his death and was in good health, equipped with a copper axe, a longbow, arrows, and a dagger.
Maixner emphasized that Oetzi serves as a valuable source of knowledge about the past. While Sarhan called for further research to determine whether the yeast poses any harm to the mummy, Nikolay Oskolkov, a researcher from the Latvian Institute of Organic Synthesis who was not involved in the study, pointed out that the Iceman’s microbiome appears to be dynamic rather than frozen. He cautioned that the yeast samples were only collected in 2010 and 2019, providing limited evidence of their long-term presence, and suggested they may be relatively recent arrivals to Oetzi’s body.
In 2023, scientists established that Oetzi is primarily descended from farmers from present-day Turkey, and recent assessments have revealed that his head may have been balder and his skin darker than previously believed.
