Humans were already infected with the ulcer-causing bacterium Helicobacter pylori around 58,000 years ago when man and micro-organism migrated out of Africa.
In the online issue of Nature, Mark Achtman and colleagues report that the key patterns in the distribution of H. pylori genetic diversity mirror those of its human host. As in humans, there is a continuous loss of genetic diversity with increasing distance from East Africa. Humans and H. pylori also seem to have spread from East Africa over the same time scale, suggesting that their association predates the 'out of Africa' event.
The team also found that the genetic makeup of H. pylori is more diverse than that of humans, so analyses of the micro-organism's DNA might aid future work on human geographic diversity.
Mark Achtman (Max-Plank-Institut für Infektionsbiologie, Berlin, Germany)
Abstract available online.
(C) Nature press release.
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