A surprising new study has found that humans migrating out of Africa may have spread a number of nasty diseases to Neanderthals in Europe and Asia.

Researchers at Cambridge and Oxford Brookes believes that early humans spread genital herpes, tuberculosis, tapeworm, and a host of other diseases to their Neanderthal cousins some 50,000 years ago, according to a University of Cambridge statement.

Unfortunately for the Neanderthals, they had no natural immunity for these diseases, and it may have even resulted in their extinction 40,000 years ago.

The Neanderthals in Eurasia would not have been adapted to the tropical diseases the human body had learned to endure, and would have been quite susceptible to these diseases. And it probably wasn’t any one disease that did them in: researchers think that individual bands of Neanderthals were wiped out by their own individual infection disasters, which may have varied depending on the group.

“Humans migrating out of Africa would have been a significant reservoir of tropical diseases,” Dr. Charlotte Houldcroft, from Cambridge’s Division of Biological Anthropology, said in the statement. “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.

“However, it is unlikely to have been similar to Columbus bringing disease into America and decimating native populations. It’s more likely that small bands of Neanderthals each had their own infection disasters, weakening the group and tipping the balance against survival,” she added. “We are beginning to see evidence that environmental bacteria were the likely ancestors of many pathogens that caused disease during the advent of agriculture, and that they initially passed from humans into their animals.”

The findings were published in the American Journal of Physical Anthropology.