Back in the 1950s, colonial officials and European scientists working in the vast, underexplored interior highlands of Papua New Guinea noted the spread of a strange disease amongst the southern Fore people. Locals called it kuru, the shaking death, as it usually started off as uncontrollable tremors, progressing into dementia and mood swings, and finally over the course of six to 12 months developing into an always-lethal coma. At its height, from 1957 to 1968, kuru killed over 1,100 people, or up to two percent of the population per year, and seemed to hit women, children, and the elderly especially hard. At first, the disease perplexed observers and the Fore alike, leading people to attribute it to anything from a slow-moving virus to a psychosomatic illness to black magic. But eventually, even if the mechanics of the disease remained obscure, the cause revealed itself: Kuru was the result of cannibalizing human brains.
Before it was outlawed and slowly eradicated in the 1950s and ‘60s, cannibalism was a key part of honoring the dead for the Fore. Women were tasked with dismembering the bodies of the departed and cooking them for a funerary feast—but they often saved the brains, seen as especially desirable, for themselves, the young, and the elderly. They saw those who died of kuru as fair game to eat as well, helping to spread the disease, which can incubate in the body for up to 40 years before manifesting symptoms. But now, in a strange twist of fate, a group of English and Papuan scientists have discovered that eating human brains and surviving kuru may have led to a rapid evolutionary advance amongst the Fore. This new discovery could help us conquer not just this rare disease, but protect against mad cow disease and even help us to fight back against dementia and Parkinson’s disease as well.
Although this may sound like a random grab bag of diseases, they’re all neurological conditions either definitely or allegedly caused by aberrations in prion proteins. Although prions are a standard (if little-understood and only recently identified) part of our biology, they have a habit, when put under certain stresses, of folding out of shape. When that happens they become like a contagious zombie inside one’s brain—a lifeless force that, as soon as it bumps into another prion, has the power to bend it out of shape as well. These prions clump together, slowly mounting up a cascade of always-lethal neurological degeneration. Mad cow and its variants (Creutzfeldt-Jakob disease in humans, scrapie in sheep, and various wasting diseases in other animals), caused by eating the brain or nervous tissue of an infected animal, are definitely the most famous of these prion diseases. But the process of degeneration looks fairly similar in many cases of Alzheimer’s and Parkinson’s as well, suggesting that prions can spontaneously clump even in people who don’t eat infected brains.
[youtube ratio=”0.5625″ position=”standard” caption=”Kuru: The Science and The Sorcery Documentary “]
Ever since the spread of mad cow disease at the dawn of the millennium, when the study of prion diseases began in earnest, we’ve understood that many cases of the disease arise naturally because of genetic predispositions. And just as gene mutations can lead to prion misfolding, other genetic variations can increase or decrease one’s susceptibility to the disease as well. By the late 2000s, we were even experimenting with altering the prions of cows to see if we could breed mad cow-immune cattle. But most of this research remained exploratory, never spilling over into anything therapeutic or preventative, leaving prion diseases ultimately untreatable.
A few years back, scientists realized that some members of the Fore seemed to have developed a possible immunity to kuru, their own local prion disease. The scientists sampled blood and conducted genealogical studies on hundreds of people who’d participated in multiple kuru-causing cannibalistic rituals and survived, finding a couple of genetic variations in the cannibalistic populations that were far over-expressed in those who’d survived kuru outbreaks. These initial studies were interesting, but they were mainly descriptive, lacking in insights as to how to use this potential immunity to prevent kuru, much less to address other common prion diseases.
Now, this newest study, published by John Collinge of University College London, a long-time mad cow researcher, has proven the power of these genetic variations against not only kuru, but also other prion diseases. By splicing this variation into mice, Collinge and his associates were able to prevent prion folding when the mice were exposed to kuru and Creutzfeldt-Jakob disease alike. And by showing how to prevent prion folding in these cases, it may help us to understand the process in general, developing preventative and therapeutic treatments for anything from mad cow to Parkinson’s. That’s a long way off, but it’s an extraordinary ray of hope in an often-bleak field.
Collinge theorizes that this genetic variation is a direct result of the Fore’s long-term exposure to brain cannibalism and prion diseases. Calling it a great example of Darwinian evolutionary selection amongst humans, he’s pointed out that kuru favored the survival of those who could develop a resistance to the disease. And because the mechanisms of kuru are so similar to other diseases, this evolutionary leap has wound up giving humanity a leg-up in the fight against prion terrors.
It’s probably worth pointing out that this newest study is not an endorsement of neural cannibalism. This prion resistance was the result of a long-term practice and came only after severe, devastating diseases ripped through an isolated population. It’s also worth noting that we’re not in imminent danger of a great prion disease outbreak, given the controls we’ve established to handle infected animals and the fact that the mad cow outbreak wasn’t nearly as catastrophic as we’d all feared. But there’s always the risk of the development of a new transmission vector. And it’s true that thousands of people could be incubating prion diseases contracted from mad cow or other sources, ready to express themselves at a later time. Then there’s the fact that dementia and other (possible prion-related) neurodegenerative disorders strike millions every year.
If Collinge’s research continues to bear out, we can use the evolutionary quirks bred by the Fore people to better understand these neurodegenerative threats, warding against them in the future, or treating and alleviating their effects when they come. But along with these developments comes troubling proof that engaging in the taboo of cannibalism may have, in the long term and after great pain and suffering for hundreds, led to advances with the potential to help millions.
