A new study published in the journal Current Biology has discovered a link between viruses present in Neanderthals and Denisovans half a million years ago, and modern diseases such as AIDS and cancer. The research suggests that ‘endogenous retroviruses’ are hard-wired into the DNA, enabling them to be passed down over thousands of generations.

British scientists from the universities of Oxford and Plymouth compared DNA from Neanderthals and another group of ancient humans called Denisovans, with modern human DNA obtained from cancer patients. They found evidence of Neanderthal and Denisovan viruses in the modern DNA, suggesting that they originated in a common ancestor more than 500,000 years ago.

Approximately 8% of human DNA is made up of endogenous retroviruses (ERVs), which are DNA sequences left by viruses which pass from generation to generation. They form about 90 per cent of the 'junk' DNA, which contains no instruction codes for making proteins. However, many scientists have criticised the labelling of this part of the genome as ‘junk’ simply because it is not understood yet.

“I wouldn’t write it off as ‘junk’ just because we don’t know what it does yet,” said Dr Gkikas Magiorkinis, from Oxford University’s Department of Zoology, who co-led the research.

“Under certain circumstances, two ‘junk’ viruses can combine to cause disease. We’ve seen this many times in animals already. ERVs have been shown to cause cancer when activated by bacteria in mice with weakened immune systems,” he said.

This of course indicates that these so called ‘junk’ viruses that have been passed down over half a million years are not junk at all, but have an element of activity that may come to life again given the right circumstances.

The Oxford team now plans to look for possible links between these ancient viruses and how they are connected to HIV/Aids.

It would also be extremely interesting to know the prevalence of these kinds of diseases in ancient humans. It seems highly probable that rates of disease are far higher now as a consequence of the poisons that exist in our modern society.

By April Holloway