Ötzi the Iceman is the name given to a frozen mummy of a man who was murdered 5300 years ago. Scientists have been studying the relatively well-preserved remains since he was found in the Italian Alps in 1991. The latest finding is that Ötzi carried Helicobacter pylori, the bacteria that causes ulcers, in his gut. Many people carry H. pylori without ever developing ulcers, and scientists have identified different strains of the bacteria in different parts of the world. And that's where Ötzi's story makes a left turn. Or right, depending on how you read maps.
When they compared Ötzi’s H. pylori genome with other types from around the world, they got a surprise—Ötzi’s type most closely resembled one from Asia, not those found today in Europe or Africa. This provides insights not only into Ötzi’s health, but also the movements of his ancestors. Ötzi’s own DNA most closely resembles that of early European farmers who originally came from the Middle East. But his bacterial strain most closely matches strains in India and South Asia today, which cluster together in the hpAsia2 population. Today’s hpEurope strain has far more DNA from the African type of H. pylori than does Ötzi’s Asian strain, notes lead author Frank Maixner, a microbial ecologist at EURAC.
He says this suggests a new scenario: The ancestors of early European farmers such as Ötzi must have carried H. pylori with DNA from Asian strains perhaps in the Middle East before they migrated to Europe. Then, new immigrants carrying African microbes arrived in Europe much later, after Ötzi lived. The two types of microbes mixed in these migrants, creating today’s European strain much more recently than expected.
The findings give us a lot to think about how humans -and bacteria- migrated around the globe thousands of years ago. Read more about the discovery at Science magazine. -via reddit
(Image credit: Thilo Parg)