Modern Humans Didn't Kill Off the Neanderthals, Infectious Diseases Did, Study Finds

Modern humans have been blamed for killing off the Neanderthals by out competing them, breeding with them and even outright murdering them. But new research suggests it may actually have been infectious diseases carried by our modern ancestors as they migrated out of Africa that finished them off. Scientists studying the latest genetic, fossil and archaeological evidence claim that Neanderthals suffered from a wide range of diseases that still plague us today.

They have found evidence that suggests our prehistoric cousins would have been infected by diseases such as tuberculosis, typhoid, whooping cough, encephalitis and the common cold.

They speculate that pathogens like Heliocbacter pylori, the bacteria that causes stomach ulcers, were brought to Europe by modern humans from Africa and may have infected Neanderthals, who would have been unable to fight off these new diseases.

However, Neandethals may have also helped modern humans by passing on slivers of immunity against some diseases to our ancestors when they interbred.

Dr Simon Underdown, a principal lecturer in anthropology at Oxford Brookes University and co-author of the study, said:

"As Neanderthal populations became more isolated they developed very small gene pools and this would have impacted their ability to fight off disease. When Homo sapiens came out of Africa they brought diseases with them. We know that Neanderthals were actually much more advanced than they have been given credit for and we even interbred with them. Perhaps the only difference was that we were able to cope with these diseases but Neanderthals could not."

The findings add to a growing body of evidence that Neanderthals were not as different from modern humans as was originally thought. Recent discoveries have suggested that rather than being brutish cavemen, Neanderthals had sophisticated culture, were master tool makers and may even have had their own language.

The new study suggests that Neanderthals also suffered from many of the same afflictions and complaints that modern humans experience. Indeed, there is some evidence from caves that early humans may have burned their bedding in a bid to rid themselves of infestations of lice or bed bugs.

Dr Underdown and his colleague Dr Charlotte Houldcroft, a researcher in infectious diseases at Cambridge University and University College London, analysed recent genetic studies on Neanderthals and other early humans. They also examined recent genetic research on common human pathogens that have aimed to trace their origins and combined it with fossil and archaeological evidence.

Most evidence from the fossil record suggest that Neanderthals tended to suffer traumatic injuries as a result of their hunter gatherer lifestyle, but there are also signs of inflammation and infection.

Their study, which is published on the open source database bioRxiv, contradicts the common view that infectious diseases only really became a problem for humans in the Holocene about 11,000 years ago when humans began living in dense settlements and farming livestock.

Instead, they say many of the diseases we see around us today were common during the pleistocene when Neanderthals dominated much of Europe and Asia between 250,000 and 45,000 years ago, when they disappeared.

They say pathogens like TB, typhoid and Crimean fever that were thought to be zoonoses caught from herd animals may have actually originated in humans and were only passed to animals during the rise of farming around 8,000 years ago.

Genetic sequencing of Neanderthal and Denisovan - another early human ancestor - DNA has shown that modern humans have inherited a number of genes from these extinct species.

These include genes that provide immunity to viral infections such as tick-borne encephalitis.

Dr Underdown said this virus would probably have been common in the forested areas of northern Europe that Neanderthals inhabited and so immunity would have been an advantage.

Other genes found in modern Papua New Guineans that are involved in the immune response against viruses like dengue and influenza may have come from Neanderthals.

Analysis of ancient DNA has also shown that Neanderthals carried genes that would have protected them against bacterial blood poisoning, or sepsis. Dr Underdown said:

"There are genetic signals in the Neanderthal genome that suggest quite clearly that they were exposed to these types of diseases but also developed some resistance to them. It had been thought that many of these diseases began infecting humans with the population increases that came with domestication of animals and permanent settlements. But here we have got Neanderthals being infected by these diseases long before those developments."

(Source: dailymail.co.uk)