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Mmmm, Brains: Everything You Wanted to Know About Cannibalism But Were Afraid to Ask

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It's the time of year when seeing flesh-eating zombies on the streets is actually kind of normal. So let's talk about cannibalism. You know you're wondering.

When did all this craziness start?

Neanderthal Model from the Chicago Field Museum, 1920. Photo Courtesy of

Paleoanthropologic evidence suggests that Neanderthals were butchering each other as far back as 100,000 years ago. Bones from sites in France, Croatia, and Italy all bear marks from stone tools indicative of defleshing. Analysis of some of the bones in France revealed that the marks are concentrated in places consistent with butchery, and not ritual defleshing.

Evidence also suggests* that humans in Europe, North and South America, India, New Zealand, Australia, the Solomon Islands, New Guinea and Sumatra practiced cannibalism at various times beginning just prior to the Upper Paleolithic period. American anthropologist Marvin Harris has argued that it was common practice for humans living in small groups, but disappeared as societal groups got bigger and states were formed. Eventually, cannibalism became taboo in many cultures, and by the 19th century it persisted only among a few isolated groups in the South Pacific. Today, very few cultures are still believed to engage in the practice, though isolated instances involving individuals or small groups have been confirmed in the last twenty years (several of them involving soldiers engaged in wars in Africa).

Why would you want to eat another person?

In the days of pre-modern medicine, cannibalism was explained by a proposed black humour (the body fluids that Hippocrates believed caused moods, emotions and behaviors) that filled the ventricle and caused hunger for human flesh. Our understanding of cannibalism is a little better today, and we even have a technical term for it: anthropophagy (anthropos, or "human being," plus phagein, meaning "to eat").

Anthropologists divide anthropophagy into two categories, both rather broad: survival cannibalism and learned, or customary, cannibalism.** Survival cannibalism is what's about to happen whenever you see two cartoon characters stuck in a life raft and one of them has a thought balloon above their head depicting the other one with a roast chicken for a body. Outside of cartoons, survival cannibalism may be—given extreme and desperate enough situations—the easiest form of cannibalism to accept, and Western society has historically been relatively forgiving of it. In 18th and 19th century seagoing communities, it was pretty much accepted as something that happened from time to time as a hazard of the occupation and lifestyle. By the 19th century, sailors and fishermen had even worked out some general guidelines should the "custom of the sea" need to be performed. Straws were drawn to decide who would be killed and eaten and who would have to do the killing (usually the second shortest straw made you the killer, and the shortest made you dinner).

Perhaps the most famous example of survival cannibalism is the Donner party, a group of eighty-seven settlers heading to California in 1846. When the party reached the Sierra Nevada Mountains, the weather turned, and they were blocked by snow at a point now called Donner Pass. The party splintered into three groups. One set up camp at a nearby lake, one camped in the nearby Alder Creek Valley, and one group of 15 travelers, later dubbed the Forlorn Hope, made snowshoes and began the 100-mile journey to Sutter's Fort. While individuals in all three groups eventually resorted to cannibalism, it wasn't the feeding frenzy that most people imagine. The people who turned to eating human flesh did so as a last resort (after eating everything from boiled rawhide to leather scraps) for a very brief period of time before their rescue.

Another example, that many people know from the movie Alive, is the 1972 plane crash that left the players and staff of a Uruguayan rugby team and some of their friends and family members stranded in the Andes Mountains. As people died from their crash-related injuries, the survivors resorted to cannibalizing the dead. Some refused to eat human flesh and starved to death. Of the 45 people onboard the plane, only 16 survived the 72 day ordeal.

Cannibals carrying their master, World's Columbia Exhibition, Chicago, 1893.

Learned or customary cannibalism is pretty much what it sounds like: the consumption of human flesh in a socially prescribed, ritualized manner, often passed down through the generations. Learned cannibalism can be divided into two categories: endo- and exocannibalism. Endocannibalism is the consumption of the flesh of a person who is a member of the same group (whether family, tribe, society, culture, etc.—any defined group fits the bill), often practiced as a funeral rite. The Wari' people of the Amazon consumed the flesh of their deceased in order to transform their tribesmen into spirits that could take animal form and provide food for the tribe. Anthropologists also found that the tribe's endocannibalism also helped survivors cope with grief. Endocannibalism among Wari' ended, as it did for most other groups, in the 1960s, when missionaries and governments began to encroach on their societies.

Exocannibalism is the consumption of the flesh of a person outside of one's own social group, often as a way to intimidate an individual or group, steal another's life force, or express domination of an enemy in warfare. Certain tribes in the Fiji islands maintained ritualized acts of cannibalistic "battle rage," where captured enemy warriors were publicly tortured, killed, and consumed.

The accusation of exocannibalism may be even more damaging to enemies than eating them. When Christopher Columbus encountered the Carib Indians, he described them as "sub-human eaters of men," labeling them inferior to Europeans and not much better than animals. They were seen as a dangerous "other," and the murder of their people and theft of their land was easily justifiable because of that. The slur of cannibalism goes both ways, however. When the Spaniards arrived in Mesoamerica, and when explorer David Livingstone encountered certain African cultures, both the Aztecs and the African tribes assumed their white visitors were cannibals.

Do Other Animals Do It?

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Cannibalism is a common occurrence in thousands of species, even herbivorous and detritivorous ones, to the point where zoologists refer to it as "ubiquitous" in the natural world. Female black widow spiders and praying mantises famously practice sexual cannibalism, killing and consuming males of their species during, or after, reproduction.

Filial cannibalism, where adults eat the young of their own species, is also common among non-human animals. Groups of adult male chimpanzees have been observed to attack and eat infant chimps. Adult male elephants, dogs, bears, lions, and even some types of fish have all been observed to kill and consume infants when replacing a previous dominant males and taking over a group.

Sharks in the order Lamniformes, which includes great whites and sand tigers among others, have been known to exhibit intrauterine cannibalism, where multiple embryos are created during impregnation and the larger or stronger individuals consume their weaker siblings during development in utero.

Is That It?

Well, no. "Deep down," science writer Carl Zimmer says, "we are all cannibals. Our cells are perpetually devouring themselves, shredding their own complex molecules to pieces and recycling them for new parts." Zimmer's exploration of cellular cannibalism (and the sexual cannibalism I mentioned above) can be found in the New York Times.

* "Suggest" is the key word here, as it is with the Neanderthals. While most anthropologists agree that ritual cannibalism has occurred in certain societies around the world over the course of history, researchers are sometimes reluctant to associate it with a particular group of people without concrete evidence. The conservative view is that there is no definitive proof that cannibalism exists in a group until an anthropologist sees, with their own two eyes, a member of that group take a piece of flesh off a body and eat it. For archaeologists, the best proof that cannibalism took place in a group that no longer exists is the presence of human muscle protein in fossilized human feces.

** Cannibalism in the vein of Jeffrey Dahmer or Hannibal Lecter is known as pathological anthropophagy, the consumption of human flesh because of insanity. It's generally outside the scope of anthropology.

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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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How Experts Say We Should Stop a 'Zombie' Infection: Kill It With Fire
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Cs California, Wikimedia Commons // CC BY-SA 3.0

Scientists are known for being pretty cautious people. But sometimes, even the most careful of us need to burn some things to the ground. Immunologists have proposed a plan to burn large swaths of parkland in an attempt to wipe out disease, as The New York Times reports. They described the problem in the journal Microbiology and Molecular Biology Reviews.

Chronic wasting disease (CWD) is a gruesome infection that’s been destroying deer and elk herds across North America. Like bovine spongiform encephalopathy (BSE, better known as mad cow disease) and Creutzfeldt-Jakob disease, CWD is caused by damaged, contagious little proteins called prions. Although it's been half a century since CWD was first discovered, scientists are still scratching their heads about how it works, how it spreads, and if, like BSE, it could someday infect humans.

Paper co-author Mark Zabel, of the Prion Research Center at Colorado State University, says animals with CWD fade away slowly at first, losing weight and starting to act kind of spacey. But "they’re not hard to pick out at the end stage," he told The New York Times. "They have a vacant stare, they have a stumbling gait, their heads are drooping, their ears are down, you can see thick saliva dripping from their mouths. It’s like a true zombie disease."

CWD has already been spotted in 24 U.S. states. Some herds are already 50 percent infected, and that number is only growing.

Prion illnesses often travel from one infected individual to another, but CWD’s expansion was so rapid that scientists began to suspect it had more than one way of finding new animals to attack.

Sure enough, it did. As it turns out, the CWD prion doesn’t go down with its host-animal ship. Infected animals shed the prion in their urine, feces, and drool. Long after the sick deer has died, others can still contract CWD from the leaves they eat and the grass in which they stand.

As if that’s not bad enough, CWD has another trick up its sleeve: spontaneous generation. That is, it doesn’t take much damage to twist a healthy prion into a zombifying pathogen. The illness just pops up.

There are some treatments, including immersing infected tissue in an ozone bath. But that won't help when the problem is literally smeared across the landscape. "You cannot treat half of the continental United States with ozone," Zabel said.

And so, to combat this many-pronged assault on our wildlife, Zabel and his colleagues are getting aggressive. They recommend a controlled burn of infected areas of national parks in Colorado and Arkansas—a pilot study to determine if fire will be enough.

"If you eliminate the plants that have prions on the surface, that would be a huge step forward," he said. "I really don’t think it’s that crazy."

[h/t The New York Times]