Scientists have demonstrated the presence of a stomach bacterium from the mummified remains of Otzi, the Copper Age man, who was discovered in a glacier in 1991.
Researchers from the European Academy (EURAC) in Italy discovered in Otzi's stomach contents Helicobacter pylori, a bacterium found in half of all humans today.
The theory that humans were already infected with this stomach bacterium at the very beginning of their history could well be true. The scientists succeeded in decoding the complete genome of the bacterium.
"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 Otzi's stomach mucosa is no longer there," said Albert Zink from EURAC.
"We were able to solve the problem once we hit upon the idea of extracting the entire DNA of the stomach contents," said Frank Maixner from EURAC.
"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," he added.
The scientists found a potentially virulent strain of bacteria, to which Otzi's immune system had already reacted.
"We showed the presence of marker proteins which we see today in patients infected with Helicobacter," said Maixner.
A tenth of infected people develop further clinical complications, such as gastritis or stomach ulcers, mostly in old age.
"Whether Otzi suffered from stomach problems cannot be said with any degree of certainty, 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 Otzi," said Zink.
The scientists assume that there were originally two strain types of the bacterium, an African and an Asian one, which at some point recombined into today's European version.
Since bacteria are usually transmitted within the family, the history of the world's population is closely linked to the history of bacteria.
Up till now, it had been assumed that Neolithic humans were already carrying this European strain by the time they stopped their nomadic life and took up agriculture.
Research on Otzi, however, demonstrates that this was not the case.
"The recombination of the two types of Helicobacter may have only occurred at some point after Otzi's era, and this shows that the history of settlements in Europe is much more complex than previously assumed," said Maixner.
The findings were published in the Science Magazine.
