In 1991, two German hikers stumbled upon a frozen corpse that had been immaculately preserved beneath the ice in the Eastern Alps for over five millenia. Since the discovery, the 5300-year-old mummy – known as “Iceman” or “Ötzi” – has proven a paleomicrobiological goldmine, shedding light on diet and lifestyle practices of humans in the Copper Age.
Now, scientists collaborating across the world have isolated and mapped the genome of a bacterium in Iceman’s stomach called Helicobacter pylori, which lives happily in the guts of half the present-day population. But the particular strain found in the Iceman has provided researchers with clues about human migration patterns that have until now remained a myster and possibly added another ailment to the long list of woes that plagued everyone’s favorite frozen mummy.
Due to a handful of key characteristics – like a fast rate of mutation – H. pylori bacteria can be viewed as a marker for the history of human dispersal and migration. It is for this reason that its presence in Iceman’s ancient stomach has grabbed the attention of evolutionary biologists from Austria, Italy, South Africa, Germany, and beyond.
“It provides almost literally a mirror image of human population structure,” said Yoshan Moodley, an author on the new Iceman paper and a researcher at the University of Venda in South Africa.
Using DNA-amplification techniques, meta-genomic diagnostics, and targeted genome capture, scientists have identified Iceman’s H. pylori as a specific Asian strain. Only three such strains have ever been detected in modern Europeans. In fact, Iceman’s H. pylori represents the first evidence that this strain was already present in Central Europe during the Copper Age, roughly between the 5th and 3rd millennia BC.
Because Iceman’s strain is more closely related to Asian than various Asian-African hybrids that exist today, this finding also suggests that Asian and African strains had not yet mixed at the time that the Iceman lived.
“We can say now that the waves of migration bringing African H. pylori into Europe had not occurred in earnest by the time the Iceman was around,” Moodley said.
And even though only about 10% of current H. pylori carriers develop ulcers, it looks like Iceman may have been one of the unlucky few. While researchers don’t know how for sure whether he would have experienced stomach pain, it likely was not the worst of his problems.
“He had a rough lifestyle,” Moodley said. “He was walking a lot in the mountains. He had degenerative diseases in his lower back and knee. He had some intestinal parasites, and Lyme Disease.”
Shockingly, none of these ailments contributed to his ultimate demise: he was killed by an arrowhead unleashed by an unknown enemy.
Though the bacteria in Iceman’s gut provide only a single sample, scientists are excited to connect the dots with research in other mummies around the world – just not in ancient Egyptian mummies, unfortunately, because their stomachs were removed as part of the mummification process.
“I think that Ötzi’s benefit to all of us is that we keep pushing back frontiers of human activity,” said Stanford archaeological scientist Patrick Hunt.
Hunt and others anticipate that Iceman will continue to be the gift to science that keeps on giving.
“It’s highly improbable that there will ever be another Ötzi – the circumstances of the way he was discovered and preserved are very extraordinary,” said James Dickson, a professor of archaeobotany and plant systematics at the University of Glasgow. “If you think back 100 years – there was no radiocarbon dating, and so on and so forth. If we project 100 years into the future, what on earth will we have found out?”