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14 Zany Facts About Zebras

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Zebras are more than just striped members of the horse family. Some are rugged mountaineers, some have spots instead of stripes, and some of them bark like dogs. Read on to discover these and other bizarre facts about zebras. 

1. A ZEBRA’S COAT IS A GIANT BAR CODE—AND WE CAN SCAN IT.

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Every zebra has a unique pattern of stripes. And scientists can use the patterns like bar codes to identify individuals in a herd and keep track of them over time.

Compared to today’s methods, the first efforts to identify zebras by their stripes were pretty low-tech. Hans and Ute Klingel, a husband and wife team, pioneered stripe recognition with Grevy’s zebras back in the 1960s. First, they photographed a bunch of zebras. Then they developed the pictures in a dark room they erected right in the field. Next, they created a card index with coded, hand-written notes on each animal’s pattern. See a few of their cards here.

These days, special software can scan images of zebras and identify individuals by “reading” their stripes like bar codes. It can even compensate for changes in posture and weight, including pregnancy. 

2. ZEBRA STRIPES MAY SERVE AS BUG SPRAY OR AIR CONDITIONING. 

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For decades and decades, scientists have wondered why zebras have stripes. One prevailing theory held that the stripes confused predators, making it harder for, say, a lion to pick out an individual zebra from a stampeding herd. 

Lately, more intriguing theories have emerged. Some scientists think that stripes keep zebras cooler. The dark stripes soak up more sunlight than the light ones, and this stirs up eddies of wind that swirl heat away. Other researchers discovered that biting flies avoid striped patterns. And the two theories might be linked: Biting flies prefer hot temperatures, so they may be less likely to bite a cooler zebra. 

3. BUT ZEBRAS DON’T ALWAYS HAVE BLACK AND WHITE STRIPES. 

Yathin S Krishnappavia Wikimedia // CC BY-SA 3.0

There are three species of zebra, and many subspecies. They come in different sizes, body shapes, stripe patterns—and, to a certain extent, even colors. The white stripes can verge on cream and the dark stripes can be black or brown. Some subspecies have pale, shadowy stripes between the larger dark ones. Plus, there are all sorts of mutations and variations. The occasional zebra has spots and some are so pale they're almost entirely white

4. MOUNTAIN ZEBRAS ARE RUGGED.

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One of the three zebra species, the mountain zebra, lives mostly in hilly, rocky places in South Africa and nearby Namibia. It has especially hard, sharp hooves that help it climb and keep its balance in rugged terrain. And while this rugged critter can’t grow a mountain man beard, it does have a bizarre, prominent neck flap called a dewlap.

5. PLAINS ZEBRAS ARE SMALL AND NUMEROUS. 

Walter Voigts via Wikimedia // CC BY-SA 3.0

Plains zebras are the smallest. They’re also the most abundant—in fact, they’re the most numerous of all the wild members of the horse family. They roam across much of southeastern Africa. 

Plains zebras come in all sorts of subspecies, and there’s a lot of coat variation between. For example, as you travel farther south across Africa, plains zebras will have fewer stripes on their legs. Nobody’s sure why, but it may have something to do with temperature or populations of those biting flies. 

6. GREVY’S ZEBRAS ARE LARGE AND PRESIDENTIAL. 

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Found in Kenya and Ethiopia, Grevy’s zebras have a more donkey-like shape, with huge round ears. They’re the largest wild members of the horse family, and can weigh up to 990 lbs. (Yes, domestic horses get much bigger, but that’s because we’ve spent thousands of years breeding them into all sorts of shapes and sizes; some are enormous.) 

These zebras are named after a President of France. In 1882, Emperor of Abyssinia (now Ethiopia) Menelik II presented one as a gift to French President Jules Grévy. Ever since then, they’ve been named in honor of Grévy.

7. TO TELL THEM APART, LOOK AT THE BUTT.

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There are plenty of useful field marks for distinguishing the zebra species, but one is to look at the pattern on the rump. Mountain zebras have a “gridiron” pattern of small stripes above their tail. Plains zebras have broad bands across the rear. Grevy’s zebras have a sort of triangle pattern on the rump, with lots of small lines near the tail. Once you learn these differences, you’ll tell them apart with ease—just be sure to explain to your safari companions why you’re so fascinated by zebra butts. 

8. ONE EXTINCT ZEBRA HAD A STRIPE-FREE BUTT. 

A quagga at the London Zoo in 1870. Image credit: Frederick York via Wikimedia // Public Domain

The quagga, a remarkable subspecies of the plains zebra, was mostly yellow-brown and un-striped below its shoulders. Native to South Africa, it was driven to extinction by European settlers and hunters. The last quagga died at the Amsterdam Zoo in 1883.

Incredibly, a group called the Quagga Project, based in South Africa, has been working to resurrect this subspecies. They pick plains zebras that look the most quagga-like and breed them together, hoping to awaken any quagga genes that may still be present. The project has drawn criticism, however: some argue that recreating an animal’s appearance isn’t the same as restoring its unique behavior and ecological role.

9. ZEBRA ROMANCE ISN’T EASY.

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Mountain zebras and plains zebras live in small groups consisting of one stallion (male) and a handful of mares (females). You may notice that this ratio is a little askew. Where do the “extra” males go? Stallions that haven’t secured a herd will gather to bro down in roving bachelor bands. Some of those bachelors may try to take over a pre-existing herd, but it's no easy task. First, a bachelor must defeat the lead stallion. Then, he waits for the females to warm up to him—which may take up to three years.

And then there’s the Grevy’s zebra. A mature Grevy’s stallion doesn’t seek to command a herd of females—he stakes out some land. Ideally, he claims a territory that has some nice food and water. Then he hunkers down and plays the waiting game. Female Grevy’s zebras are wanderers, and the stallion is hoping that the ladies will visit for some sustenance and perhaps romance. Young Grevy’s males who don’t have territories will buddy up into groups and also wander. Those territorial stallions tolerate their presence—that is, until a receptive female wanders by. Then things get ugly. (Don't click on that link unless you're comfortable with graphic zebra romance.)

10. DON’T RIDE A ZEBRA. 

No, really: don’t. Humans domesticated horses thousands of years ago, modifying their appearance and behavior and turning them into compliant, beloved companions. But zebras were never domesticated. It’s sort of like the difference between a poodle and a wolf. There are several reasons that humans domesticated horses instead of zebras, including a zebra’s ducking reflex. Watch this video to learn more.

11. ZEBRAS NEIGH, BRAY, AND … BARK.

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Zebras make all sorts of weird sounds. Mountain zebras whinny like a horse, Grevy’s zebras bray like a donkey, and plains zebras bark like dogs. Alarmed stallions may squeal or snort, and happy zebras may push air between their lips when they’re eating. 

12. ZEBRAS CAN MAKE ZORSES, ZONIES, ZEDONKS, AND MORE. 

A zedonk, or hybrid zebra-donkey. Image credit: Getty Images

Zebras can breed with other members of the horse family. The offspring come in an amazing variety of semi-striped patterns, and are usually sterile (meaning they can’t have young). Zorses are the offspring of horse stallions and zebra mares. Zedonks are the products of zebra stallions and donkey mares. Zonies come from zebras and ponies. And there are many more bizarre possibilities

13. ZEBRAS ARE IN TROUBLE.

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Two out of the three zebra species aren’t doing so well. Grevy’s zebras are in the deepest doo-doo: habitat loss, hunting, competition for food and water with domestic grazing animals, and disease have all taken their toll. The International Union for Conservation of Nature (IUCN) labels them endangered and says they’ve “undergone one of the most substantial reductions of range of any African mammal.” There are only about 2000 of these big-eared zebras left.

Mountain zebras face similar threats, and are listed as Vulnerable, which is one rung better than Endangered. There are about 9000 left. 

Plains zebras, on the other hand, are in pretty okay shape. Despite local declines from habitat loss and hunting, their population is fairly stable

Preserving zebras is important because they’re amazing, and because they’re food for majestic predators like lions. But also… 

14. PLAINS ZEBRAS MAKE GRASSLANDS TASTIER.

For pickier grazers such as Thomson’s gazelles and wildebeest, zebras are a huge boon. Those striped heroes have special digestive systems that can quickly process lower-quality forage. Plains zebras are often the first to enter an un-grazed grassy area. They’ll munch on older, harder, less nutritious plants that other grazers can’t eat. Once the old stuff is cleared out, tender new growth pops up. More selective grazers will then wander in and eat the good stuff.

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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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Why Your iPhone Doesn't Always Show You the 'Decline Call' Button
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When you get an incoming call to your iPhone, the options that light up your screen aren't always the same. Sometimes you have the option to decline a call, and sometimes you only see a slider that allows you to answer, without an option to send the caller straight to voicemail. Why the difference?

A while back, Business Insider tracked down the answer to this conundrum of modern communication, and the answer turns out to be fairly simple.

If you get a call while your phone is locked, you’ll see the "slide to answer" button. In order to decline the call, you have to double-tap the power button on the top of the phone.

If your phone is unlocked, however, the screen that appears during an incoming call is different. You’ll see the two buttons, "accept" or "decline."

Either way, you get the options to set a reminder to call that person back or to immediately send them a text message. ("Dad, stop calling me at work, it’s 9 a.m.!")

[h/t Business Insider]

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