Genetic evidence: cannibalism common in human past
17 July 2012
SAM KEAN | Slate Magazine | Extracts
HUMANS IN DURESS EAT OTHER HUMANS, always have. A 100-pound adult, after all, could provide his starving comrades with around 40 pounds of precious muscle protein, plus edible fat, liver, blood, and gristle.
Some archaeological evidence suggests that humans have tucked into each other even when not famished. But for years, it was unclear whether most non-starvation cannibalism was religiously motivated and selective, or culinary and routine. According to some scientists, our DNA suggests routine….
Cannibalism per se isn’t bad for you; you can even spoon up and eat most human brains safely. But if your guest of honor happened to suffer from Creutzfeldt-Jakob or another prion disease, those misshapen proteins can slither into your own gray matter when you eat him. This exact scenario unfolded in Papua New Guinea last century, among some highland mountain tribes who consumed their relatives in ritual funeral feasts.
At its peak in the late 1950s, the PNG epidemic killed 200 tribal members per year. Strangely, though, while many victims died as children, some people exposed to prions lived four decades or more before succumbing. And some people who consumed tainted brains never showed any symptoms.
DNA explained the discrepancy. More than three-quarters of the long-term survivors had two different versions of the prion gene. Both versions produced healthy, functioning proteins, despite their slightly different shapes. The shapes made a difference only when people ate tainted brains, and faced an invasion of the infectious vampire prions.
While the bad prions could latch onto one of the two shapes just fine, the other shape could shrug them off and avoid corruption. Overall, then, having two different versions of the prion gene slowed the destruction down.
If the word “prion” has been tickling the back of your brain until now, that’s probably because of the outbreak of mad-cow disease in the United Kingdom in the 1990s. Mad-cow is a prion disease that arose when humans ate cows that had been forced to cannibalize each other on factory farms.
People exposed to mad-cow prions included both those who had two identical copies of the prion gene, and others who had a mixed pair. Strikingly, though, of the hundred-plus deaths from mad-cow, every victim except one had identical copies.
In other words, British victims showed a similar genetic pattern to victims in Papua New Guinea: Having two different copies of the prion gene seemed to offer resistance to bad invading prions.
The funny thing is that the prion gene is highly conserved: The A-T-G version was universal among our primate ancestors. Mutations to it therefore should be rare. But the same basic mutation showed up in scads of people in both the United Kingdom and Papua New Guinea, two almost antipodal points on the globe. Follow-up work uncovered the mutation most everywhere else in the world, too.
How did this spread so far? Perhaps through genetic drift, a random diffusion process. Or perhaps—as a few scientists argued in a controversial paper from 2003—cannibalism was so popular in our past that all human ethnic groups had to stockpile alternative versions of the prion gene or else they’d get wiped out….
Other scientists have since found flaws in the 2003 paper that, they say, led the original team to overestimate our ancient appetite for cannibalism. But even these critics acknowledge that the prion gene has a strange history, and that outbreaks of cannibalism like the one in Papua New Guinea could well have altered the DNA of many ethnic groups.
And regardless of exactly why the exotic versions of the prion gene spread, the fact that they have means that many of us can now taste the most forbidden flesh of our fellow human beings with relative impunity. Only problem is, they can do the same to you.
My distant ancestors on my mothers side were the Celtic/Irish tribe Magoudh- subsequently modified to read McKee, MacKay, Mackey, Mackie etc.
These ancestors were among other Irish tribes who started raiding the north-west coast of Scotland, inhabited by the traditional aboriginal tribes whom the Romans called "Pictoriae" or Picts.
This because these people commonly tattooed their bodies often from head to foot with intricate designs such as used to be seen in the Central Province and In New Zealand (where the practice is going through a renaissance, although not often complete body coverage).
The Picts were never conquered by the Romans, who actually recruited a legion of these fierce guerill-warriors headed by a Roman Centurion and used them to terrorise unruly populations around the whole empire.
The reason for peoples' abject fear of the Picts was not simply that they were fearsome fighters, but that they used to cook and eat their vicitims.
My Magoudh ancestors, being also pretty fearsome guerilla fighters, vanquished many groups of Picts, made peace, settled down and intermarried.
I have no problem at all with the fact that many of my forebears were practising cannibals. And this applies to all of us!
Posted by: John Fowke | 18 July 2012 at 08:41 AM
I asked wife's grandfather in 1974 if he ever had eaten human flesh and he said as a small child had done so in feast in SW Lavongai area. Recalled it was that of neighbouring Tigak tribesman.
Posted by: Arthur Williams | 18 July 2012 at 04:17 AM
I once asked my students to go home and ask their families if anyone in the family had eaten human flesh.
The next day I ask them for a show of hands to see how many their ancestors had eaten human flesh.
One third of the children put up their hands indicating that their ancestors had eaten a small portion of someone who had died.
The reason was that they believed they would acquire the stength and good qualities of the dead person.
Only a small part was ever eaten and I was pleased to know that the practice no longer existed.
Posted by: Trevor Freestone. | 17 July 2012 at 04:53 PM