Ötzi’s gut bacteria reveal stomach problems, new human migration timeline

Around 5,300 years ago, Ötzi the Iceman was a man on the run. Showing signs of having been in a fight earlier, he seems to have been fleeing across the Italian Alps when he was brutally attacked, ending with Ötzi bleeding out in the snow—as an arrow had pierced a major artery in his left arm.

But the ice preserved his body, until glacial melting exposed the corpse in 1991. From that point on, the mummy of the Iceman has been a human history goldmine. Evidence shows Ötzi had a host of health issues, like Lyme disease, gallstones, and worn joints; his DNA has helped scientists understand human evolution and population movements (and shows he has living relatives today); and he has the world’s oldest known tattoos.

Now, a new team of international scientists working with paleopathologist Albert Zink and microbiologist Frank Maixner from the European Academy (EURAC) have managed to uncover some new interesting information: Ötzi might have suffered from gastrointestinal issues, and modern Europeans may have been more influenced by “recent” immigrations than previously though.

Gut bacteria

Ötzi’s stomach contents revealed that, at the time of his death, he was fighting off an infection of Helicobacter pylori. H. pylori is a bacterium thought to have been present in humans for some 100,000 years—and since it’s shared between families, it can be used to trace the movement of human populations across the millennia.

This discovery came as an unexpected (but welcomed) surprise to the researchers.

“Evidence for the presence of the bacterium Helicobacter pylori is found in the stomach tissue of patients today, so we thought it was extremely unlikely that we would find anything because Ötzi’s stomach mucosa is no longer there,” explained Zink in a statement.

“We were able to solve the problem once we hit upon the idea of extracting the entire DNA of the stomach contents,” added Maixner. “After this was successfully done, we were able to tease out the individual Helicobacter sequences and reconstruct a 5,300 year old Helicobacter pylori genome.”

And this genome came with some other surprises, too. The modern European H. pylori genome seems to be a blend of African and Asian genetic material—and it was believed that this combination of the genes happened between 10,000 and 52,000 years ago, according to the paper in Science. But Ötzi put a hitch in this hypothesis.

“We had assumed that we would find the same strain of Helicobacter in Ötzi as is found in Europeans today,” explained Thomas Rattei from the University of Vienna, a colleague of Zink and Maixner. “It turned out to be a strain that is mainly observed in Central and South Asia today.”

In other words, the mixture of Asian and North African genes didn’t happen until sometime after 5,300 years ago—and not 10,000 or more. To the researchers, this suggests that there was likely an influential human migration around Ötzi’s time period that added more of the North African genes to H. pylori’s genome.

“The recombination of the two types of Helicobacter may have only occurred at some point after Ötzi’s era, and this shows that the history of settlements in Europe is much more complex than previously assumed,” said Maixner.

99 problems and ulcers might have been one

Hpylori has another claim to fame, though. It’s found in some 50% of all modern humans (usually in more impoverished populations), and was somewhat recently discovered to be the root cause of most gastric ulcers. In fact, roughly 10% of those infected with the bacterium develop diseases thanks to it, such as ulcers or gastric carcinoma.

In Ötzi’s case, the specific H. pylori found in his system is associated with inflammation of the stomach lining, and the body showed signs of waging battle against an active infection of the bacteria.

“We showed the presence of marker proteins which we see today in patients infected with Helicobacter,” said Maixner.

However, it’s uncertain of whether this was a one-time problem or an issue he had faced for some time.

“Whether Ötzi suffered from stomach problems cannot be said with any degree of certainty,” said Zink, “because his stomach tissue has not survived and it is in this tissue that such diseases can be discerned first. Nonetheless, the preconditions for such a disease did in fact exist in Ötzi.”

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Feature Image: South Tyrol Museum of Archaeology