Even if you don't immediately recognize the words "prion" or "Kuru", the history has seeped into popular culture, like a horrifying fairy tale that just happens to be true. Once, there was a tribe in New Guinea that ate the dead. It wasn't the kind of fakey cannibalism you see in the movies, with hunters rushing out to spear people for sustenance. Instead, it was about respecting your elders. When a member of your family died, you ate them—you took a part of them into yourself. And that included the brain.

But over time, these people found themselves plagued with a terrible illness. Children and perfectly healthy adults, usually women, would suddenly begin to lose control of their limbs. They would jerk and shudder. Within weeks, they wouldn't be able to stand up at all. And then they died. Everybody who had those symptoms died.

Eventually, Western scientists would learn the awful truth. When the people from New Guinea ate their ancestors they were also eating a disease. It attacked their brains—riddling the tissue with holes. The New Guineans, the Fore people, called the disease kuru. In their language it meant "trembling" or "fear".

Today, we know a little bit more about the disease, kuru. We know it's not caused by a virus or a bacterium or a fungus. We know it's related to other brain-damaging diseases, including Creutzfeldt-Jakob disease, which turns healthy adults senile and kills them within a year of the onset of symptoms; scrapie, which affects sheep; and the dreaded bovine spongiform encephalopathy -- mad cow disease.

Tying all these diseases together is a scary little something called a prion. On August 16th, I attended a lecture by Jay Ingram, a Canadian journalist who has written a book about prion diseases, called Fatal Flaws. The lecture taught me a lot about prions, but it also taught me about some of the flaws inherent in trying to live-tweet a lecture as I'm listening to it. When the subject is so scary—and so confusing—even well-intentioned live tweets can go awry.