Ancient ancestors had tummy bug too
22:00 04 November 2002
NewScientist.com news service
Gaia Vince
Proceedings of the National Academy of Sciences The stomach-infesting bacterium Helicobacter pylori has been living in humans for at least 11,000 years - much longer than previously thought, say US researchers.
A team at New York University analysed bacterial DNA present in stomach biopsies taken from two groups of Venezuelan volunteers of different ethnic origin. The first was an urban group of European or mixed ancestry. The second was an Amazonian group from an isolated population of indigenous Amerindians.
The researchers found H. pylori present in all the samples. But those in the urban group had a Western European genetic variation, whilst those in the Amazonian group had an East Asian strain.
This provides strong evidence that the bacterium was present in the emigrating population of Asians believed to have crossed the Bering Strait 11,000 years ago to colonise the Americas. The bug would then have been transmitted down through the generations in the indigenous population.
"H. pylori has been living in the human gut for a minimum of 11,000 years, but probably far longer," says Martin Blaser, professor of microbiology, who led the research.
Beneficial effects
Previously, it was believed that the Europeans introduced H. pylori to the Americas at the time of Columbus in the 15th Century. There is also evidence from Egyptian mummies that H pylori infected people about 1800 years ago.
The bacterium is associated with the development of peptic ulcers and gastric cancer, raising the question of how a damaging bug has persisted in humans for so long.
But Blaser told New Scientist: "More than 90 per cent of people with H. pylori never get ulcers or stomach cancer and anyway these diseases only occur after reproductive age, so they do not effect natural selection."
He believes his work suggests H. pylori infection may even have some beneficial effects.
"Over the last century as people have become cleaner and antibiotics have become widespread, the reduction in H. pylori has led to an increase in diarrhoeal diseases and oesophageal cancer," he says. "So it is possible that H. pylori is good for the oesophagus and bad for the stomach."
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.242574599)
Thanks Blam, a good idea for a GGG topic. ;')
Not possible, clearly the researchers' methodology is skewed. Everyone knows the bacterium can't be older than 6000 years, becaue that's what Bishop Ussher says. Jeeze.
/s