The laughing death
MARK GREENER suggests that the traces of past cannibalism might help us identify future threats to mankind
It sounds like a Doc Savage yarn. Doc and the Fabulous Five race to Papua New Guinea (PNG) to discover the source of the mysterious ‘laughing death’ among cannibals and save the industrialised world. Remarkably, the story is almost true. Studies of kuru – a brain disease that ravaged cannibals – offer insights into some of the current great enemies of humanity as well as helping account for the demise of certain ancient civilisations.
Whatever a diet of Umberto Lenzi films would have you believe, cannibalism is not necessarily ‘primitive’ and, extreme famine aside, is rarely just gastronomic. It can be sophisticated, indicate deep and profound respect, and act as a strong social glue. Cannibalism allows kith, kin or combatants to imbibe the deceased’s vital essence, which, in turn, helps form, maintain and embed relationships between and within social groups.
For example, kinship in the Fore culture in the Eastern Highlands of PNG is fluid and social, rather than fixed and genetic. Adoptees and immigrants become kin regarded identically to biological relatives, provided they are loyal and meet their obligations. For centuries, eating dead kin as a mark of respect and mourning helped strengthen the Fore’s social cohesion and transcend purely genetic relationships.
Then, 60 years ago, doctors realised that kuru was killing one in ten Fore, mainly women and children. Kuru began with headaches, aching limbs and joint pains. It also damaged parts of the brain that control emotion, sometimes causing inappropriate euphoria and laughter: one of the Fore’s names for kuru was the ‘laughing death’.
The cause remained a mystery until the early 1980s, when researchers isolated the ‘proteinaceous infectious’ (prion) agent that caused kuru. Your body twists many proteins into different shapes; some ‘misfolded’ shapes form deposits that damage the surrounding tissue and also ‘seed’ further aggregations of the same misshapen protein. So, the damage spreads.
The Fore did not eat kin who died from dysentery or leprosy, but they ate kuru victims. Kuru develops slowly, appearing between four and 20 years after eating infected human tissue. So, eating kuru’s victims, and infected people without symptoms who died from other causes, seeded the prion in the next generation. Women and children were more involved in ritual cannibalism than men, and kuru always killed within three months to two years of symptoms emerging. That’s why fewer men died from kuru and some Fore villages “were almost devoid of young adult women”.
Then, in 1996, biologists realised that people ‘caught’ variant CreutzfeldtJakob Disease (vCJD), another devastating brain prion disease, from cattle infected with bovine spongiform encephalopathy (BSE): mad cow disease. We now also know that modern ‘corpse medicine’ can spread CJD. For instance, people contracted CJD from grafts of the dura mater (a membrane that surrounds the brain and spinal cord) and cornea; blood transfusions; and pituitary or growth hormones extracted from corpses, now largely replaced by genetically engineered versions.
More recent evidence links spreading deposits of misfolded proteins to several common conditions, including type II diabetes, Parkinson’s and Alzheimer’s diseases. Yet prions have been enemies of humanity for millennia. Human remains from non-burial contexts, such as those simply left on the floor, at several archæological sites show disarticulation, marks and heat-changes consistent with food preparation. Researchers also found human myoglobin in fossilised human fæces collected from some sites linked on other evidence to cannibalism. Only skeletal and cardiac muscles produce myoglobin. So, if you have myoglobin in your fæces, you ate some heart or skeletal muscles. Myoglobin’s chemical composition allows biochemists to identify the species eaten.
So, several strands of mutually reinforcing evidence suggest that cannibalism was commonplace, widespread and culturally diverse. We may never know from archæology alone just how widespread or varied cannibalism was, but it may leave molecular footprints in the sands of time. Generally, we have two copies of each gene. Many elderly Fore who had eaten human flesh on several occasions but didn’t develop symptoms had one copy of a particular gene. Kuru killed those with two copies before they could reproduce. The pattern of this gene worldwide suggests that we’ve encountered prions throughout our evolution, either transmitted by a prehistoric version of BSE or through cannibalism.
Prions might help explain the rapid demise of some cultures. Kuru swept through Fore territory in a few years, entering from the northwest around 1900 and arriving in the south by 1930. A prion disease could, in theory, destroy a culture in a few generations, especially if, as in the Fore, young people were more affected than older generations.
We’re used to bacteria, parasites and viruses – such as the Black Death, malaria or Spanish flu – wiping out millions. Today, we need to worry about infectious misfolded proteins. However, as kuru illustrates, insights into the greatest enemies of humanity can come from unlikely sources.