How researchers traced degenerative convulsions to ritual cannibalism in Papua New Guinea
The traditional beliefs of the Fore people of Papua New Guinea describe a living world, guarded by ancestors and stirred by sorcery. Everyone is believed to have five souls, with the ama, aona and yesegi passing on blessings, talents and power to a person’s family after they die. Unfortunately, the rituals to help those souls transition from life could also pass an unusual disease that would cause convulsions, dementia and eventually death. Known as kuru, or “shivering,” this illness defied explanation for decades, as it wasn’t caused by normal pathogens like bacteria, viruses or fungi. Fortunately, the source of the infections was identified, and what was once an epidemic blamed on sorcery is now eradicated from Fore society.
Looking for patterns with no pathogens
Most of the world didn’t know about the Fore people until 1930, and by 1950 there was growing concern about the disease that could cause everything from a loss of motor function to uncontrollable laughter. At that point, there were some symptoms that warned of its onset, such as headaches and joint pain that would usually be overlooked, followed by the more ominous difficulty walking. Clearly something was attacking people’s nervous systems, but no bacteria, virus or fungus could be identified as the culprit. Environmental contaminants were ruled out. Genetic conditions were targeted, but after mapping the family trees of victims, there was no pattern that suggested any particular lineage was in more danger than another.
Thankfully, a pattern did emerge among the victims. Adult women and children were more likely to contract kuru than men, and those women often knew each other. Eventually, it was determined that the women weren’t carrying a contagion themselves, but they were sharing the infection through their traditional duties during funerary rituals. In order to free and care for some of a dead relative’s souls, women prepared and ate the dead body. The women’s bodies were thought to protect and tame souls of the deceased, although in the preparation process they sometimes gave portions to attending children as well. This cannibalism would have probably been safe in most cases, but it proved to be the perfect transmission point for kuru when the deceased had already been infected.
Poisoned by proteins
As these patterns were brought to light, researchers still couldn’t explain what the cause of the disease was on a physiological level. Sometimes the full explanation isn’t completely necessary to help people though, and experiments on chimpanzees proved that eating an infected body did indeed cause kuru. Even infected brains that had been preserved in formaldehyde for years could cause an infection, making it clear that the ritual cannibalism was putting people at risk. With this information, traditions were changed, and infection rates dropped off, with the last death being reported in 2009, probably after years of incubation in the victim’s body.
The last bit of good news is that the underlying mechanism causing this debilitating condition was also identified. Nobody had been wrong in their earlier exclusion of bacteria or viruses, as the infections were driven by misfolded proteins called prions. Rather than fold into the necessary shape to perform normal functions in the body, these proteins somehow start folding into clumps, collecting more protein mass along the way. The prions mostly amassed in the brain and nervous system, eating away at people’s lives until they had no control over their own bodies anymore. We still don’t know exactly how prions get started, but with the outbreak of bovine spongiform encephalopathy, or Mad Cow disease throughout the 1990s among cows fed other cows, there does seem to be a connection to even inadvertent cannibalism. At the very least, it seems that you should be very sure about what meat you eat, and what that meat may have eaten when it was alive.
Source: When People Ate People, A Strange Disease Emerged by Rae Ellen Bichell, The Salt