London, March 14 (ANI): A new research has shown that Christopher Columbus, along with other medieval European explorers, did not introduce anthrax in the Americas, as the deadly bacteria arrived in the continent thousands of years earlier, when Stone Age humans crossed the Bering land bridge.
Anthrax bacteria can live in soil for decades as tough spores, until a grazing animal inhales them. Then, they multiply explosively, kill the animal, and bleed into the soil to await the next victim.
It is only since the intense genetic analysis of anthrax that followed the 2001 attacks, though, that enough has been known about the bug to trace its family tree in the Americas.
Anthrax initially evolved in southern Africa, earlier work has demonstrated.
According to a report in New Scientist, Paul Keim of the Northern Arizona University, who led the genetic investigation of the attacks, said that normally anthrax spores do not move far from their dead victims, so it was probably humans carrying scavenged, spore-infested hair and hides who moved one anthrax "family" into northern Africa, then across Eurasia.
"That transfer then continued," Keim said.
His new work confirms previous studies suggesting that many strains of American anthrax came on European wool and cattle in recent centuries.
The Ames strain used in the anthrax attacks, for example, naturally occurs only in Texas, but differs from Eurasian anthrax by only about eight mutations, showing it is a recent immigrant.
But, the analysis also shows that most of the anthrax lurking in the grasslands from northern Canada to Mexico differs by up to 106 mutations, showing it branched off from the Eurasian form long ago - roughly when humans and animals entered the Americas from Siberia then moved south as grasslands opened up in central Canada around 13,000 years ago.
"The line of descent shows a clear gradient from north to south," Keim said.
The fact it moved from north to south shows it was carried by the invading humans, not animals moving back north as the glaciers retreated. (ANI)