Cannibalism is one of the most universal taboos. Frowned upon in nearly every culture around the world (even if there isn't always a law on the books to punish this very specific act), cannibals populate the worst of our ghost stories and horror movies. From Sawney Bean and his clan in the hills of Scotland, to Hannibal Lecter in Silence of The Lambs, cannibals are everywhere.

Like any dietary trend, though, if you're going to start eating people you should do it in moderation. Otherwise, you might start to see some serious side effects stemming directly from this particular decision.

There's a reason we stopped eating each other.

Cannibalism is at least as old as humanity, and probably a bit older. According to Business Insider, cannibalism was fairly common millions of years ago, but the practice died out because it was both not sustainable, and because humans have always achieved more when we combine our efforts. Wondering if Dave is going to eat you tends to make for a difficult work relationship, and it led to those who practiced cannibalism being shunned by potential allies.

That's not to say cannibalism didn't survive in some form; all you need to do is look at a history book to find how common it's been throughout our history. From the Aztecs, to the West Indies, to the Pacific Islands, there are plenty of times and places where cannibalism has been an accepted part of life.

The word itself actually came from Europeans mispronouncing the name of the Carib tribe in the late 1400s, referring to them as Canibs. Since they practiced ritual cannibalism (the "twice a year on Christmas and Easter" kind of pleiotrophy), they became the source for the word.

And even if cannibalism being accepted by an entire culture is rare, there are still plenty of outlying incidents, like stranded campers, prisoners in Soviet gulags, and other extreme events where people have had to literally make a choice between eating the dead, and joining them.

No matter the reason for eating human flesh, though, every cannibal faces a very real threat whenever they eat a member of their own species, beyond social repercussions and potential punishment; prion diseases.

What the hell are prion diseases?

I promise, they are a real thing.

Prion is a word that sounds like a mcguffin in a sci-fi medical drama, but prions are a very real thing. AsScientific American points out, the word is actually a shortening of the term proteinaceous infectious particle.

Prions each start life as a protein with no nucleic acid genome. When these proteins come into contact with other proteins, they bond with them, and start changing them zombie style. Soon enough an army of malformed proteins is shambling through your body, changing as many of your formerly healthy building blocks as they can into members of the horde, breaking you down from the inside.

What does that look like? Well, if you've ever seen an animal suffering from mad cow disease, or a human with Creutzfeld-Jakob disease, then you already know. Both of these conditions, as well as other prion diseases, lead to brain deterioration, loss of motor control, and ultimately to death.

And in case you were wondering, human brains and bone marrow are the two parts of the human body that are just lousy with prions, making them the riskiest parts of a person to consume. Which is really too bad, because the brain is also the organ filled with slow-burning energy that will sustain you, should you be trapped on a mountainside with no other options.

However, no matter what parts of a person you eat, it's possible to ingest prions, which is why long-term cannibals may look more like half-crazed mutants from the New Mexico badlands than suave professors of psychology.

Interested in more?

If you'd like to see more content just like this, make sure you check out my Horror archive here on Vocal where you can find articles like "5 "The Purge" Movies They Should Make Next," as well as "What Is The Monster In "The Ritual"? A Mythological Theory".

Or if you're interested in more practical horror topics, you might enjoy "How To Get Rid of a Body," over on my writing blog The Literary Mercenary!