There is a 50 per cent chance an acid-resistant bacterium is lurking in your tummy, waiting to provoke a peptic ulcer that might eventually turn into stomach cancer. According to a study published in the journal Science, Ötzi the Iceman, one of the best examples of a naturally preserved mummy just joined the list of the stomach bug-plagued.
An international team of researchers has reconstructed the genome of the bacterium Helicobacter pylori from food residues found in the stomach of the 5,300-year-old frozen mummy. In order to extract the tissue and food samples from the Iceman’s digestive tract, they had to unthaw Ötzi who is normally conserved at a temperature of -6° C and at a relative humidity of 98 per cent.
The scientists were not only able to prove the presence of H. pylori in the Iceman’s gastrointestinal tract but also found indications his immune system had in fact reacted to an infection caused by the bug.
“We showed the presence of marker proteins which we see today in patients infected with Helicobacter,” says Frank Maixner of the European Academy of Bozen/Bolzano (EURAC), one of the study’s lead authors.
These findings provide clues that the Iceman may indeed have suffered from a gastric ulcer, although Albert Zink, a paleopathologist at EURAC who led the team, is quick to add that this will be hard to prove as the gastric mucosa has long decayed.
What really astonishes the researchers is not only that they found the pathogen of one of today’s most common stomach diseases, but also the origins of the mummy’s bug.
“We had assumed that we would find the same strain of Helicobacter in Ötzi as is found in Europeans today,” explains Thomas Rattei, co-author and computational biologist at the University of Vienna. “It turned out to be a strain that is mainly observed in Central and South Asia today.”
Today’s European strain of H. pylori is thought to be a hybrid between ancient Asian and African strains of the bacterium. Until now, scientists assumed Neolithic migrants already carried the newer European bug when they first arrived. But as Ötzi still carried the original Asian strain, this may not have been the case.
As H. pylori easily spreads between family members (via saliva, vomit or faeces), its genetic evolution is closely related to our own history. That is why scientists use it to trace humans’ migration routes.