Ötzi the Iceman: stomach bug sheds light on human migration

New stomach microbes taken from Otzi the Iceman, a 5,300 year old mummified corpse found frozen in the Ötztal Alps in 1991, are providing exciting new insights into the human migration from North Africa into Europe.

More than five thousand years ago in the European Alps, a man was shot by an arrow, then clubbed to death. His body was subsequently mummified by ice until glacier retreat exhumed him. Since then, the mummy has been a bounty of intriguing information for scientists, and the latest analysis continues this trend. Scientists shared their findings in the journal Science.


The 5,300 year old mummy “Otzi.” Image credit: Reuters, Institute for Mummies and the Iceman

Researchers tested the contents of Otzi’s stomach and found a bacterium called Helicobacter pylori, an age old pathogen that about half the people on Earth have in their gut. The sample extracted from Otzi is the oldest specimen to be sequenced.

Surprisingly, the strain of bacteria in his gut shared ancestry with an Asian strain. In contrast, most Europeans have a bacterium with North African lineage. Researchers then used geographically distinct bacterial strains to reconstruct human migrations.

If the analysis of gut bacterium in Otzi is a good representation of Europeans 5,300 years ago, results suggest that human migration from Africa had not occurred yet.

“We can say now that the waves of migration that brought these African Helicobacter pylori into Europe had not occurred, or at least not occurred in earnest, by the time the Iceman was around,” said Yoshan Moodley, a researcher at the University of Venda in South Africa.

Despite the intriguing conclusion, deeper questions remain.

“Something really dramatic has happened in the last 5,000 years in H. pylori DNA that hasn’t happened in human DNA. There will be an interesting reason for that… we haven’t figured it all out yet,” said Daniel Falush, a geneticist at Swansea University.


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