When members of the Fore tribe in Papua New Guinea ate the brains of their extended kin at funerals, it was their way of paying respect. Unfortunately, the ritual also helped spread kuru prion disease, a form of Creutzfeldt-Jakob disease (CJD)—a rare but fatal brain disease that can lead to dementia and works on a molecular level much like Alzheimer’s and Parkinson’s. Reporting in the journal Nature, researchers say they've isolated the mutated gene that helped some members of the tribe survive the brain disease that at its height in the 1950s claimed 2% of the population annually. "Several individuals right at the epicenter of the epidemic, they have this difference that we have not seen anywhere else in the world," says a study co-leader.
"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," the University College London researcher, who's studied kuru for decades, tells the Guardian. To test the prion protein gene he bred mice with it and found they were resistant to all forms of CJD, not just kuru, reports the BBC. His team is already working on follow-up research to learn more about how the gene works and perhaps even devise a way to prevent CJD and other forms of dementia. (One hospital's mistake last year exposed 18 patients to CJD.)