Migrating humans may have killed off Neanderthals by accident

"Humans migrating out of Africa would have been a significant reservoir of tropical diseases," said Charlotte Houldcroft from the University of Cambridge's Division of Biological Anthropology, in a statement. "For the Neanderthal population of Eurasia, adapted to that geographical environment, exposure to new pathogens carried out of Africa may have been catastrophic."

Researchers at Cambridge and Oxford Brookes universities analyzed DNA from ancient bones and pathogen genomes. They concluded that some infectious diseases are probably thousands of years older than originally thought. They think Helicobacter pylori, a strain of bacteria that causes stomach ulcers, likely infected humans for the first time in Africa at least 88,000 years ago and first arrived in Europe about 52,000 years ago. But recent evidence suggests that Neanderthals became extinct about 40,000 years ago, supporting this new theory that modern humans are responsible for killing off Neanderthals.

"Once agriculture came along, these diseases had the perfect conditions to explode, but they were already around," said Houldcroft.

Researchers say that the infections would not have all happened at once, as they did when Christopher Columbus and other Europeans arrived in the Americas and killed off the native people. Instead, they would have spread between small groups of about 15 to 30, weakening them and making it nearly impossible to survive.

Many theories exist to explain the demise of the Neanderthal population, including climate change, human cognitive superiority, competition for food due to humans hunting with dogs and wolves, and direct competition and violence between humans and Neanderthals, said Houldcroft.

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By: edison