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How Did Egyptians Move Heavy Rocks For The Pyramids?

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The pyramids aren't just old, they're really really old: We are closer in time to Cleopatra than she was to the building of the first pyramids. That mind-boggling time-chasm might explain why the pyramids have proved to be a source of fascination and speculation for modern humans, who can't imagine how our ancient forefathers got anything done without technology, let alone building structures large enough to be seen from space.

Stacking the blocks into the towering iconic shape is often marveled at as a feat of mystery, but just assembling the necessary materials is equally miraculous.

For the Great Pyramid of Giza—which is thought to have been built over a span of two decades for fourth dynasty pharaoh Khufu—over 2,300,000 giant blocks of limestone and granite weighing an average of two and a half tons had to be transported to the site from quarries—some from places like Aswan, more than 500 miles away.

Archeological evidence suggests that the ancient Egyptians used crude wooden sleds to transport the heavy building blocks. But if you've ever dragged something through the sand, you can understand why these sleds might not have eased this task. The weight of the blocks would cause the sled to sink slightly and, as you dragged them, sand would accumulate in front of the sled, increasing the resistance.

A recent study in the journal Physical Review Letters proposes an explanation for how the Egyptians made use of the sleds that is based on a principle most people are familiar with: While dry sand is easily pushed around, wet sand is malleable but more rigid. This is why you need moist sand to give your sandcastles structural integrity at the beach. The correct ratio of water to sand—which is variable, but typically between 2 percent and 5 percent of the volume of sand—causes the water droplets to create capillary bridges that bind the individual grains of sand into a smoother, stronger surface.

In experiments, the force required to pull sleds across sand was reduced by a full 50 percent when the right amount of water was added. Not only would it make sense for the ancient Egyptians to have utilized this tactic, there's evidence to suggest that they did. A wall painting from the tomb of Djehutihotep shows a hoard of workers moving a statue of the Upper Egypt nomarch on a sled. While rows of workers are shown heaving heavy ropes attached to the statue, a single figure is painted perched atop the sled pouring what could certainly be water on to the ground in front of him.

"In fact, Egyptologists had been interpreting the water as part of a purification ritual, and had never sought a scientific explanation," Daniel Bonn, who led the study, told the Washington Post.

The science is sound, but that doesn't necessarily mean it overrules the Egyptologists' theories about Djehutihotep's wall painting or that it applies to the pyramids, which were built over 600 years before Djehutihotep lived. Most reports of the study have assumed that applying their findings to the pyramids is something of a foregone conclusion. Adding water to the sand to decrease friction certainly makes sense, but that doesn't necessarily mean it's what the Egyptians did.

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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Big Questions
Why Don't Valentine Hearts Look Like Real Hearts?
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Love is in the air this month, and images of two-lobed hearts are all over everything: candy, cards, decorations, you name it. That the heart is symbolic of love and passion isn't surprising—ancient Greek and Roman thinkers, including Aristotle, thought the organ was the center of all emotions. Why the heart symbol you see everywhere in February doesn't look anything like an actual human heart, though, is a little less clear.

The symbol goes at least as far back as the 1400s, when it appeared on European playing cards to mark one of the red suits, though it may even be older than that. The shape is pretty much a mystery, though. There are a few different hypotheses to explain it, but none of them have been confirmed.

One suggested origin for the symbol is that it comes from the ancient African city-state of Cyrene, whose merchants traded in the rare, and now extinct, plant silphium. The plant was used to season food, but doubled as a contraceptive. A silphium seedpod looks like a valentine's heart, so the shape became associated with sex, and then with love.

Another possibility is that the shape is a crude representation of a pubic mound, the vulva, a pair of breasts, buttocks, or a pair of testicles. It may even have come from a poor attempt at drawing an actual heart. A lousy artist, an inaccurate description of the subject, or a malformed model all could have led to that shape.

The Catholic church explains the symbol as coming from a vision that Saint Margaret Mary Alacoque had, where the "Sacred Heart of Jesus"—associated with love and devotion by Catholics—appeared in this shape surrounded by thorns. But Alacoque didn't have this vision until the late 1600s, well after the symbol was already documented. This makes it the unlikeliest of origin stories, but the church's frequent use of the shape was probably a driving factor in popularizing it as a symbol of love.

This story originally appeared in 2012.

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