Public Release: 

The Iceman's gut microbes shed light on ancient human geography

American Association for the Advancement of Science

Analysis of microbes from the gut of the "Iceman", a famous 5,300-year-old European glacial mummy, provides insights into not only his health status right before he was murdered, but historical human geography as well. Surprisingly, a strain of bacterium in his gut shares ancestry with an Asian strain, in contrast to the fact that most modern Europeans harbor a strain ancestral to North African strains. Helicobacter pylori is a bacterium that has resided within humans for so long that different strains have evolved as humans migrated around the world, meaning that genetic analysis of strains of this bacterium can be used to map the history of human geography. Therefore Frank Maixner and colleagues took biopsy samples to look for this pathogen, which is estimated to occur in up to 50% of people in low-income settings. The authors found a single strain of H. pylori that was producing virulence factors, indicating that the Iceman may have been feeling ill on the day he was murdered. Surprisingly, the strain the Iceman harbored shared a high level of ancestry with prehistoric Indian strains and even higher ancestry with most modern European strains, showing just a trace from North African strains. By contrast, modern strains in Europe share much higher ancestry with North African strains - indicating an intimate influence of recent human migrations on Europeans that, the authors suggest, must have occurred after the Copper Age, assuming that the stomach contents of the Iceman is representative of Europeans 5,300 years ago.

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