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10 Roaring Facts About Jaguars

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A few different jaguars have found fame on YouTube over the last few years: In 2013, a National Geographic video of one of the cats taking down an unsuspecting crocodile went viral. And a year later, 4.5 million viewers watched some spectacular footage of one swimming like a champion. But these cats deserve more than just 15 seconds of fame. Here are 10 incredible facts about jaguars that might help you properly appreciate the next hit video.


These big cats used to have an enormous geographic range, stretching from Argentina to the southwestern United States. In centuries gone by, jaguars were among the top predators in Arizona, New Mexico, Texas, and southern California. Overhunting, habitat loss, and armed livestock owners completely wiped out the local population in at least three of those states. In 2011, a male was photographed in the Santa Rita Mountains near Tucson, Arizona. Nicknamed El Jefe (Spanish for “the boss”), this cat quickly became a minor celebrity because at the time, no other wild jaguar specimens were known to reside anywhere in the U.S. Then, in 2016, a trail camera in Fort Huachua, Arizona took some snapshots of what looks like a different male. “We are examining photographic evidence to determine if we’re seeing a new cat here, or if this is an animal that has been seen in Arizona before,” Jim deVos, a member of the state’s Game and Fish department, told the press. While there's not yet an official verdict on whether it's El Jefe or there's a new cat in town, you can compare these photos and draw your own conclusions.


"Pound for pound, jaguars pack a stronger punch” than a lion or tiger, says biologist Adam Hardstone-Rose. Back in 2012, Hardstone-Rose co-authored a study that compared the standard bite forces of nine cat species. The data showed that, in terms of sheer power, jaguars can’t compete with tigers, who exert 25 percent more force when chomping down. But proportionately speaking, the smaller felines wield the most powerful bite of any big cat. “The strength of [its] jaw muscles, relative to weight, are slightly stronger than those of other cats. In addition—also relative to weight—its jaws are slightly shorter, which increases the leverage for biting,” Hardstone-Rose explains.


Jaguars aren’t finicky. They’ll eat just about any animal they can overpower. Fish, birds, deer, armadillos, peccaries, porcupines, tapirs, capybaras, anacondas, caimans, and nesting sea turtles are just a few of the jaguar’s dinner options. Armadillos, caimans, and sea turtles are all heavily armored creatures whose hides are tough enough to repel most would-be predators, but jaguars aren't daunted: They know where to bite down. Some big cats, like lions, tend to kill by suffocation, biting the windpipe area of the victim’s neck until it asphyxiates. Jaguars take a different approach. When one of these spotted felines goes in for the kill, it generally delivers a swift, powerful bite to the back of target’s head right where the skull meets the spinal cord. With crushing force, the jaguar’s teeth are driven into the neck vertebrae. If all goes well, the bite will efficiently incapacitate the prey animal.


To quote Sir David Attenborough, the jaguar is “a killer of killers,” hunting some pretty dangerous game. Consider El Jefe, who has eaten at least one bear. Last year, wildlife biologist Chris Bugbee was leading Mayke, his jaguar-tracking dog, through the famous cat’s territory when they came upon the stripped remains of a young adult black bear. The back of the animal’s skull had been crushed, and some suspicious toothmarks were present. Bugbee also found jaguar scat at the scene. An analysis of the fecal matter revealed strands of black bear hair. According to biologist Alertis Neils—who is also Bugbee’s wife—this is probably the first recorded instance of a jaguar killing a black bear. The ranges of these two species don’t overlap to a great extent, as the former is seldom seen in the U.S. while the latter is considered endangered in Mexico [PDF]. Regarding El Jefe’s bear hunt, Neils said, “It was north against south, and south won.”


All felines can swim, but many would prefer to stay high and dry. Jaguars, in contrast, voluntarily enter rivers and streams so often that they’re considered the most aquatic of the big cats. The cats have been known to pursue fish and caimans underwater. On hot days, they can even be found wallowing in bodies of water to cool off. Well-suited for endurance swims, the felines have been seen traversing rivers that are a mile wide or more. Don’t believe us? Watch this.


Most people assume that the black panther is a distinct species of feline. But the “black panther” is really an umbrella term that applies to individual leopards or jaguars who have a condition known as melanism. Melanistic animals are born with an unusually large amount of dark-colored pigment in their skin, scales, feathers, or fur. This can give them a striking, jet black look from head to toe. Jaguars and leopards with melanism—so-called black panthers—are so dark that, in many cases, you can barely see their spots. At the other end of the spectrum are albino jaguars, which are a good deal rarer than melanistic ones. Nonetheless, a few have been sighted in Paraguay.


The fossil record tells us that jaguars first evolved in Eurasia, where the species—whose scientific name is Panthera onca—has long since gone extinct. The cats then crossed the Bering land bridge and entered the Americas around 1.5 million years ago. The average jaguar was a lot larger in those days, with a wide range. Fossilized jaguar bones have been found in Florida, Maryland, Nebraska, Tennessee, and Washington. From this fossil record, scientists have deduced that prehistoric P. onca were 15 to 20 percent bigger than the animals alive today.

The decrease in body size might have helped jaguars survive the last ice age. For predators back then, the competition was fierce. While prehistoric jaguars were impressively large, they still would’ve been dwarfed by the saber-toothed cat Smilodon fatalis and by another massive feline called the American lion. Both were big-game hunters. So to avoid directly competing with either species, jaguars probably started pursuing smaller animals like peccaries. Some paleontologists suspect that, over time, this trend would’ve forced the jags themselves to get smaller. In the end, the shrinkage paid off: Most of the mega-mammals on which Smilodon and the American lion depended gradually died out. But the jaguars’ relatively diminutive prey animals are still around today. Size matters in nature—but bigger isn’t always better.



The South American republic adopted its current coat of arms (pictured above) on February 25, 1966. Since the jaguar is Guyana’s national animal, it’s fitting that two of them appear in the design. As you can see, the cats come with props. The one on the left is grasping a pick axe, which represents the country’s mining industry. Meanwhile, on the right, we see a cat that’s grasping a sugar cane and a stalk of rice. These symbolize the historic importance of both crops—plus those who farm them—in Guyana.


This species belongs to the same genus, Panthera, that includes the lion, tiger, leopard, and snow leopard. With the exception of the snow leopard, all of those cats emit deep roars—and so, too, does the jaguar. The same cannot be said of the other felines that roam North America. Mountain lions, bobcats, lynx, ocelots, jaguarundis, and margays emit all kinds of sounds (ranging from low hisses to horrific shrieks), but none are considered genuine roars. On the flip side, those Panthera cats cannot purr, which is something that many of their smaller relatives—including the tabby who lives in your house—do with gusto. Life is full of tradeoffs.


No wild jaguar has set foot in Florida since prehistoric times. But the Jacksonville Zoo and Garden does have an award-winning jaguar display, and it was the first American zoo to ever breed these near-threatened felines on a regular basis. On July 18, 2013, the 50th cub was born at the zoo—the same birthday as the owner of the Jacksonville Jaguars, Shahid Khan. So, when a contest was held to determine what the kitten's name would be, the public chose Khan. In July 2016, Jaguars wide receiver Arrelious Benn and safety Jarrod Wilson dropped by the zoo to help the cat celebrate his third birthday. 

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iStock // Ekaterina Minaeva
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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Cs California, Wikimedia Commons // CC BY-SA 3.0
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]