Contagious diseases traced to Neanderthals

London: Ancestors of modern-day humans are thought to have wiped out the ancient Neanderthals from Europe by passing on diseases and infections when they moved out of Africa and into the continent previously dominated by them.

The Neanderthals, who would only have developed resistance to the diseases of their European environment, are most likely to have been infected with a bacterium that causes stomach ulcers, the virus that causes genital herpes, tapeworms and tuberculosis.

The researchers said that some infectious diseases are likely to be many thousands of years older than previously believed.The diseases and infections to which the hunter-gatherers were exposed would have made them less able to find enough food and remain healthy.

The diseases would have spread through sexual contact between the two species. "Humans migrating out of Africa would have been a significant reservoir of tropical diseases," said Charlotte Houldcroft from the University of Cambridge in Britain.

"For the Neanderthal population of Eurasia, adapted to that geographical infectious disease environment, exposure to new pathogens carried out of Africa may have been catastrophic," Houldcroft added.

The findings showed Helicobacter pylori -- a bacterium that causes stomach ulcers -- as highly likely to have been passed by humans to Neanderthals.