Ötzi the Iceman has long been treated as a frozen messenger from the Copper Age. But his remains might not be completely preserved in time, a new study suggests.
A team has identified cold-adapted yeasts that could have colonized Ötzi during his glacial deep freeze as well as genetic traces of the gut microbes he died with five millennia ago. The results, published June 3 in Microbiome, suggest the modern microbiome of the remains could affect Ötzi’s preservation.
Conservationists keep Ötzi’s remains in a specialized facility in Italy at –6° Celsius to simulate the glacier in which they were entombed and prevent degradation. Given the low temperature, it was surprising to find the four ancient species of yeast still viable, says Albert Zink, an anthropologist formerly with the Eurac research center and now at Ludwig Maximilian University of Munich.
“We also found ancient DNA from these species, which proves that they persisted in Ötzi and accompanied him over thousands of years while he was preserved in the ice,” Zink says. That finding aligns with the fact that scientists think Ötzi’s remains thawed and refroze several times, especially in the first 1,500 years after his death.
The team thawed Ötzi’s remains to 4° Celsius for five hours and collected the resulting runoff. The researchers also took swabs from Ötzi’s body at key locations, and samples of his skin and other tissues. In addition, the researchers analyzed soil collected from the glacier when Ötzi was discovered, the air in the museum and the water used to keep his chamber humid.
The researchers then reconstructed the genetics of multiple microbe species in the samples and distinguished between them. Attempts to grow colonies of Ötzi’s ancient microbes yielded the four viable yeast species, which the team considers “relicts,” or living time capsules, of Ötzi’s time in the ice after his death. Cultures from the remains of Ötzi’s internal bacteria did not grow.
The viable cultures suggest Ötzi “is not a static relic but a dynamic biological interface,” the team writes. Alpine archaeologist Patrick Hunt of Stanford University, who was not involved in the study, says the conclusion is “right on the mark,” and the study notes there could be a danger of decomposition if the yeasts are not kept frozen.
Ötzi’s remains are “the most important archaeological science finding of the 20th century and up until the present,” Hunt says. Studies have shown that Ötzi was destined to go bald, had been tattooed in several places and ate a high-fat meal before he died. He carried an ax made of copper from far away and wore leather clothes. Scientists have had an incredible look at this past life from his remains. But that can only continue if they have a good idea of the cold-loving, potentially damaging microbes stored with him. The team’s “analytical findings on ongoing microbial contamination,” Hunt says, “are vital to whatever interventions are needed” for the preservation of the remains.