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The front (left) and back (right) of a 3000-year-old copper mask. Small holes near the edges suggest the mask could have been attached with threads. Someone tried to repair the fracture near the left eye—note the holes near it.
Cortés & Scattolin in Antiquity, 2017

Rainy Season in the Andes Reveals the Oldest Known Copper Death Mask

Original image
The front (left) and back (right) of a 3000-year-old copper mask. Small holes near the edges suggest the mask could have been attached with threads. Someone tried to repair the fracture near the left eye—note the holes near it.
Cortés & Scattolin in Antiquity, 2017

A good downpour can be an archaeologist’s best friend. A recent rainy season in the northwest corner of Argentina revealed an ancient copper mask, green with rust, that had been hidden in the dirt for the last 3000 years. It's the oldest known copper artifact in the Andes—the longest continental mountain range on earth—and one of the oldest metalworks ever found in South America. Its discovery complicates the long-standing idea that metalworking began on the continent in Peru, thousands of miles north.

The mask looks a bit like a Jack-o’-lantern, with a little triangle for a nose and small openings for the eyes and mouth. Residents of the village of La Quebrada stumbled across the mask, as well as some bones, sticking out of the dirt in 2005. Shortly after, archaeologists came in to excavate the site, and they found that the mask wasn’t resting on just one burial, but was covering a collective grave with 14 bodies.

“We don’t know exactly what the actual meaning of the mask was in the context of this pre-Hispanic society,” archaeologist Leticia Inés Cortés, of Argentina’s National Council for Scientific and Technical Research, tells Mental Floss. Ancestor cults are very ancient and widespread in the region, Cortés says, so the mask could be a representation of the ancestor of the group and the rest of their community. Later DNA tests might reveal the relationships between the deceased.

The burial site was located near the 1900-year-old settlement of Bordo Marcial. However, radiocarbon dates showed that the tomb and mask are much older—dating back to 3000 years ago, before any villages even existed in the region.

During this time period, people in the area were just beginning to leave their hunter-gatherer way of life. But even before they truly settled down and started farming, they apparently figured out how to take advantage of the rich copper sources in the region that are still mined today.

Cortés, who described the mask in a new report in the journal Antiquity, tells Mental Floss that there’s been a tendency to treat Peru as the epicenter for technological innovation in the region. This mask, meanwhile, shows “that there is no one place for technological innovation, but many, including this region of the southern Andes.”

In other words, it’s not like a few geniuses in the central Andes figured out how to melt down metal to make beautiful objects and their invention spread from there.

Archaeologists might have previously assumed that cultures only started making fine metal objects when they had elite ruling classes and a capacity to create agricultural surpluses to free up time for skilled workers. But the mask from Argentina also builds on other evidence from the region demonstrating that displays of wealth might pre-date sedentary life.

“The discovery underscores the idea that social complexity—that is, a hierarchical social order—is not required for the emergence of early metal working,” says Mark Aldenderfer, an archaeologist at the University of California, Merced, who wasn’t involved in the study.

Aldenderfer previously discovered the oldest gold artifacts in the Americas, in the form of a necklace dating back to 4000 years in Peru near Lake Titicaca, when people in that region were just starting to settle into villages.

“The circulation of metal artifacts and their interment with the dead suggest that new forms of wealth accumulation and networking began to emerge during this transitional period,” Aldenderfer tells Mental Floss. "I suspect that the copper mask from Bordo Marcial reflects a similar social context."

Original image
The front (left) and back (right) of a 3000-year-old copper mask. Small holes near the edges suggest the mask could have been attached with threads. Someone tried to repair the fracture near the left eye—note the holes near it.
iStock // Ekaterina Minaeva
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technology
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!

Original image
The front (left) and back (right) of a 3000-year-old copper mask. Small holes near the edges suggest the mask could have been attached with threads. Someone tried to repair the fracture near the left eye—note the holes near it.
Cs California, Wikimedia Commons // CC BY-SA 3.0
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science
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]

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