It is well documented that cannibalism can lead to degenerative brain diseases including commons forms of dementia and Creutzfeldt–Jakob disease. But scientists have discovered that a tribe, known for its cannibalistic tendencies, has developed a resistance to certain neurological diseases.

The finding could have implications in treating or even preventing brain disorders such as Alzheimer's.

The research was carried out by the Medical Research Council’s (MRC) Prion Unit at University College London.

They studied the Fore people, a once-isolated tribe in eastern Papua New Guinea.

Until the 1950s this group of about 20,000 people, found in the Okapa District of the Eastern Highlands Province, had little contact with the outside world.

But when contact was made, anthropologists made a startling discovery; the Fore would take part in gruesome cannibal ceremonies at funerals.

In a way to honour the dead, the women and children would eat the brains, while the men would eat the flesh.

This had a disastrous effect on the Fore people - namely, it allowed a deadly molecule to spread and cause an incurable and fatal disease known as kuru.

At its peak in 1960, the disease was killing up to two per cent of the Fore population each year and significantly more in women, up to eight times as much as the men.

Despite since being prohibited, its effects still linger in the tribe today.

But a new paper has found that while the ritual was disastrous and caused a deadly epidemic, it may have also caused a genetic mutation that made the Fore immune to kuru other diseases.

Survivors appear to have developed a variant of the human prion protein, which can produce resistance to prion diseases such as Creutzfeldt-Jakob disease (CJD).

Understanding prions like this more could help in the treatment of dementias such as Alzheimer’s and Parkinson's disease.

Professor John Collinge, the Unit Director, who leads the kuru research programme, told MailOnline that this was the first time a natural genetic mutation to prevent kuru had been spotted in humans.

In the study, the researchers examined those who had been exposed to kuru but had survived many years after cannibalism ceased in the 1950s.

They found that these survivors had developed an important prion protein gene in order to protect themselves against kuru - a rare example of human evolution in action.

The researchers tested this process by engineering the same genetic change in mice, altering just one of the 253 ‘building blocks’ - amino acids - that make up the prion protein.

Remarkably, the mice were found to develop a 100 per cent resistance to not just kuru, but all forms of CJD as well.

‘From the human genetic work the Unit has carried out in Papua New Guinea we were expecting the mice to show some resistance to disease,’ said Dr Emmanuel Asante of UCK, who led the team that produced the mice.

‘However, we were surprised that the mice were completely protected from all human prion strains. The result could not have been clearer or more dramatic.’

Professor Collinge added: ‘This is a striking example of Darwinian evolution in humans - the epidemic of prion disease selecting a single genetic change that provided complete protection against an invariably fatal dementia.

‘Much work is now ongoing in the MRC Unit to understand the molecular basis of this effect which we expect to provide key insights into how seeds of other misshapen proteins develop in the brain and cause the common forms of dementia, thereby guiding us to new treatments in the years ahead.’

The work was funded by the UK Medical Research Council and published in the journal Nature.