Neanderthals were wiped out by the ancient ancestors of modern humans but both the species are thought to have co-existed peacefully for thousands of years and interbred, resulting in modern Europeans inheriting around 2 percent of Neanderthal DNA.
Researchers studying human evolution say that these genes are responsible for increased susceptibility to potentially killer diseases such as cancers and diabetes. However they added that the interbreeding helped improve the immunity of modern humans as Neanderthals were exposed to diseases that were common at that time, to which modern humans had not been exposed.
"Studies have shown we could have taken part of our HLA system, which effects our white blood cells, from them. We got a quick fix to our own immune system by breeding with Neanderthals which helped us to survive. Studies have also already been published which show that humans outside of Africa are more vulnerable to Type 2 diabetes, and that is because we bred with Neanderthals, while those who stayed inside Africa didn't", Chris Stringer, research leader in human origins at the Natural History Museum in London, said.