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did Ötzi have a tummy bug?

Well, probably not1, in the sense that most would place on the term 'tummy bug' (where a close proximity to the toilet is a Good Thing), but it turns out that he did have some rather interesting intestinal bacteria.

Ötzi is perhaps better known as the 'Iceman', who died around 5,300 years ago in the Otztai Alps of the Italian Tyrol. (He's the subject of a fascinating web page & I have to say, I'd love to visit the museum, maybe when we next visit family in Europe.) His body, clothing, and equipment are exceptionally well-preserved & are yielding a great deal of information on life in Neolithic Europe - including, as described in the latest issue of Science, the nature of his microbiome. (You'll find the full paper here, but there's also an open-access summary here. I do have a gripe about the use of the term 'tummy bug' in the latter, though!)

In their just-published paper, Maixner's research team reports on their finding of a strain of Helicobacter pylori in Ötzi's stomach contents (he'd apparently eaten a full meal not long before he died). I've written about H.pylori before: while it's been found to be associated with development of gastritis, stomach ulcers, & sometimes cancer in a small proportion of those carrying it2, there's also evidence that it has a protective effect against other disorders, including acid reflux and oesophageal cancer. And it's been with us for a long time:

Predominant intrafamilial transmission of H. pylori and the long-term association with humans has resulted in a phylogeographic distribution pattern of H. pylori that is shared with its host. This observation suggests that the pathogen not only accompanied modern humans out of Africa, but that it has also been associated with its host for at least 100,000 years. Thus, the bacterium has been used as a marker for tracing complex demographic events in human prehistory.

Most modern Europeans carry one particular strain of this bacterium, which is believed to have originated via recombination of two earlier strains. However, the origins of these strains have been uncertain, & the researchers hoped that Ötzi's gut microbes might throw some light on this. The Iceman himself was born and lived in Southern Europe, and DNA comparisons link him to early European farmers. However, the strain of H.pylori found in his gut is most closely related to a haplotype now found in central and southern Asia, and not to those of Europe and Africa.

The detection of an hpAsia2 strain in the Iceman’s stomach is rather surprising because despite intensive sampling, only three hpAsia2 strains have ever been detected in modern Europeans. Stomachs of modern Europeans are predominantly colonized by recombinant hpEurope strains.

Maixner suggests that the Iceman's ancestors must have brought this Asian strain of H.pylori with them when they migrated to Europe. Well after Ötzi died, later immigrants from Africa brought their own strain of the bacterium, and subsequent recombination produced the modern European strain of this microbe. This is evidence for rapid evolution of H.pylori in Europe as waves of human migrants moved into and across the continent.

The researchers also noted that Ötzi's version of the bacterium represents a strain that's associated with stomach inflammation in modern humans - and that protein biomarkers expressed in his gut indicate that he had an inflammatory response to the infection. This may or may not have manifested in actual disease - his stomach lining was not sufficiently well-preserved to let them draw any conclusions on this.

 

1  Which is a real pity, as I was so going to steal my friend Grant's suggested phrase, "the Tyrolean trots", for my title :( 

 It's "found in approximately half the world’s human population, but fewer than 10% of carriers develop disease that manifests as stomach ulcers or gastric carcinoma" (Maixner, Krause-Kyora, Turaev, Hoopmann et al., 2016)

F.Maixner, B.Krause-Kyora, D.Turaev, A.Herbig, M.R.Hoopmann, J.L.Hallows, U.Kusebauch, E.Vigi, P.Malfertheiner, F.Megraud, N.O'Sullivan, G.Cipollini, V.Coia, M.Samadelli, L.Engstrand, B.Linz, R.L.Moritz, R.Grimm, J.Krause, A.Nebel, Y.Moodley, T.Rattei, & A.Zink (2016) The 5300-year-old Helicobacter pylori genome of the Iceman. Science 351 (6269):162-165 . DOI: 10.1126/science.aad2545

 
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