London, November 19 (ANI): Scientists have discovered that a cannibalistic ritual in which the brains of dead tribes people were eaten by their relatives has triggered one of the most striking examples of rapid human evolution on record.
In the middle of the 20th century, the Fore tribe of the Eastern Highlands province of Papua New Guinea was devastated by a CJD-like disease called kuru, which was passed on by mortuary feasts in which the brains of the dead were consumed.
Although the practice was banned in the 1950s and kuru has disappeared, it has left an imprint on the tribe's DNA.
According to a report in the Times, research has now identified a genetic mutation unique to the Fore that protects against the brain disease and which has spread swiftly through the population by natural selection.
In the new study, scientists analysed the DNA of more than 3,000 people from affected and unaffected parts of the Eastern Highlands, including 709 who had taken part in cannibalistic rituals and 152 who had died of kuru.
The variant in the prion protein gene, called G127V, appears to have emerged about 1800 and then became advantageous with the arrival of kuru.
As the mutation confers high or almost complete resistance to kuru, carriers have a survival advantage and have had more descendants.
About 8 per cent of people from the Purosa Valley region, where kuru hit hardest, now have the gene, which is unknown anywhere else in the world.
The findings, from a team led by Simon Mead, of the Medical Research Council Prion Unit at University College London, show how quickly human evolution can respond to new environmental pressures.
"It's absolutely fascinating to see Darwinian principles at work here. This community of people have developed their own biologically unique response to a truly terrible epidemic. The fact that this genetic evolution has happened in a matter of decades is remarkable," said Professor John Collinge, the director of the prion unit.
The research is also significant because it promises to shed light on the rogue prion proteins that cause Creutzfeldt-Jakob disease (vCJD), the human form of mad cow disease.
According to Dr Mead, "It isn't going to lead to a drug tomorrow, but it would improve our background understanding of how prion diseases work and how they might be prevented." (ANI)