New life on 5,300-year-old Ötzi Iceman's body
Scientists have discovered something shocking on the body of an ancient mummy. tzi the Iceman is home to a surprisingly diverse and complex community of microbes -- some ancient, some more modern, and even some that can survive in freezing conditions.
This study, published in the journal Microbiome, unveils new insight into the mysterious creatures dwelling in the most preserved ancient human remains to date, and has implications for both the preservation of ancient remains and cold-temperature industries.
The mummy found in the Alps in 1991, known as tzi, was discovered after the ice, which had preserved his body, began to melt. He became one of the world's most widely studied archaeological finds since his remains were opened to inspection.
According to the researchers who led the recent study, the main goal was to see which microbes had been part of tzi's microbiome while he was alive and which ones had invaded his body after his death.
Researchers took some samples for analysis. They examined the ice on the mummy's body, melted ice from inside the corpse, swabbed a few places, and used material from the mummy's stomach and intestinal tract. In addition, they also analyzed the sample of frozen soil found at the site three decades earlier, taken from the same area where tzi was discovered.
By comparing modern microbiome data with these findings, researchers have managed to filter out contaminants introduced to tzi's body after his death or intrusion during the long storage period in the glacier.
The most important finding among the study results was the identification of tzi's original gut microbiome.
The researchers discovered a great number of bacterial species that had inhabited tzi's intestines, and that had previously been detected by other scientists. However, unlike before, genetic material of bacteria that had been found in the previous study also appeared in tzi's body, which confirmed that these species were genuine and not the result of contamination after death.
The bacteria that had been detected in tzi's body were found to be uncommon in modern industrialized societies. They have also been found in only a limited number of ancient human remains.
This allowed the researchers to hypothesize that tzi's gut microbiome is an excellent source of information about the intestinal microorganisms in ancient humans before industrialization made the human gut microbiome significantly different from what it used to be.
The most surprising finding was the detection of several species of cold-adapted yeasts.
The scientists found these microscopic fungi in the skin samples, meltwater, and the mummy's stomach content. Moreover, genetic tests showed that these microorganisms are closely related to the yeast species found in the coldest places on Earth, including Antarctica.
The researchers suggest that they may have come from the glacier where the mummy was found and remained living on his body for hundreds or even thousands of years.
The study revealed both highly degraded ancient DNA and modern-day DNA from these two species. This discovery might mean that some of the microorganisms survived until today inside tzi's body. The mummy is kept at a constant temperature of around six degrees below zero centigrade and high humidity to reproduce the natural environment in which he was found.
The researchers suggest that some of the microorganisms' species might still be viable there.
The study also demonstrates that modern preservation methods may have contributed to the microorganisms that are present today.
For instance, after discovering tzi in 1991, conservators used phenol to remove fungi from the mummy's body.
The study found that three out of the four newly discovered yeasts had genes that allowed them to break down the phenol, meaning that the chemical might have acted as a food source for the yeast that was present on tzi's body and have contributed to their survival throughout the process.
The study serves as a reminder that preserving ancient artifacts can have unintended consequences for the delicate ecosystems which may be present on them.
Researchers note that the study could contribute to the improvement of conservation strategies for tzi and other ancient human remains.
By being acquainted with the microorganisms that live on the mummy and their features, scientists can control and observe changes that can affect the preservation of the ancient man.
The researchers also assume that the results of their work can have applications outside of archaeology.
For instance, cold-adapted microbes can be applied in biotechnology and fermentation processes, which will make them more energy-efficient. Researchers also note that such microorganisms can be used in different ways, and their use in industry is not excluded. Thus, while waiting for further studies, researchers have managed to find a way to save one of the world's most iconic archaeological discoveries. Moreover, more than thirty years after the mummy was discovered, tzi continues to keep his secrets and teach scientists new things about the world around him, including microbiology.
Disclaimer: Please note that this article is based on an article published in the Microbiome journal. Thus, the claims presented can be verified via the original research paper. The study's results demonstrated that tzi's Iceman's microbiome contains genetic traces of both ancient and modern microorganisms. Although the researchers propose that cold-adapted bacteria could have industrial applications, these ideas are still hypothetical and await further experimentation. Therefore, this article does not confirm that tzi's bacteria are dangerous for the general population and museum visitors specifically.
