“Why did women and children get the disease? Because they were the ones that carried out the practice – the men didn’t. It explained why it was dying out in young children – because the [Australian patrol officers] had proscribed cannibalism. You could also conclude that the disease was not being transmitted vertically from mother to child.”
By 1966, Alpers and a team of other scientists were starting to catch on to the fact that kuru was caused by something other than a viral infection, a bacterial disease, or even genetics – it was actually caused by a puzzling agent called a prion. This discovery paved the way for Baruch S Blumberg and D Carleton Gajdusek to sweep up a Nobel Prize in Physiology or Medicine in 1976 for "their discoveries concerning new mechanisms for the origin and dissemination of infectious diseases."
Prions are essentially normal proteins that have become twisted and turned to the "dark side". These infectious agents lose their functions and acquire the ability to turn other normal proteins into prions too, thereby becoming infectious.
Some of the more infamous diseases caused by prions are BSE, aka “Mad Cow disease”, and its human alternative Variant Creutzfeldt-Jakob disease – two degenerative brain disorders that share an uncanny resemblance to kuru. It’s believed that BSE is most likely the result of cows eating the recycled offal and brain tissue of other cows, just like kuru.
So, eating human brains might not always be the best of ideas, even before you get into the whole array of blood-borne illnesses that you could contract, from HIV and hepatitis to E. coli and Ebola. However, here’s where the story takes a turn. A study published in Nature in 2015 found that the Fore people who regularly ate brains had developed a resistance to prion diseases, a discovery that is still helping scientists understand degenerative brain diseases, such mad cow disease, Creutzfeldt-Jakob disease, and some cases of dementia.