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Kevin Walsh via Flickr // CC BY 2.0

5 Extinctions That Wiped Much of Life off Planet Earth

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Kevin Walsh via Flickr // CC BY 2.0

by Aliya Whiteley

The more we get to know about the history of the Earth, the more incredible it becomes. Our planet formed about 4.5 billion years ago, and for the first billion years it was without life. Then organic molecules began to form simple cells.

It’s tempting to think that from those first cells the business of evolution took hold and created the plants and animals we see today, but this simplified version overlooks some of the most catastrophic developments that happened along the way. Five mass extinction events have wiped out nearly every living thing on this planet. So the next time you’re feeling less than brave, remind yourself that you are descended from some seriously tough survivors. You’re already one of nature’s great success stories.

1. ORDOVICIAN-SILURIAN EXTINCTION—445 MILLION YEARS AGO

Most life forms were still living in the oceans at the time of the first mass extinction. There are many theories as to how that happened: global cooling that brought on an ice age, volcanic gases, or maybe changes in ocean chemistry. Whatever the cause, about 85 percent of species were wiped out.

2. LATE DEVONIAN EXTINCTION—375 MILLION YEARS AGO

The oceans recovered and teemed with life once more, and that diversity had begun to spread onto land at the time of the second mass extinction, when 79–87 percent of all species died due to environmental change. A series of several extinction events spread over approximately 40 million years wiped out most of the life on earth. The cause is unclear, but some scientists have theorized that the sudden increase in plant life could have triggered a period of anoxia (lack of oxygen). Other suggestions include volcanic eruptions on a huge scale, or another ice age.

Although plants may have triggered the destruction, it was the marine life that was hardest hit. Armored fish died out completely. Reef ecosystems vanished from the seas and were not seen again for the next 100 million years. But there were some who benefited: Into these gaps in the oceans’ ecosystems came some of nature’s hardiest survivors—the sharks.

3. PERMIAN-TRIASSIC EXTINCTION—250 MILLION YEARS AGO

This is also known as the Great Dying, and with good reason: 70 percent of land species and 90 percent of marine species disappeared, including half of all marine families. Plant life also suffered; only a few forests remained. It’s the only event in which insects also died out en masse. The devastation to life was so thorough, this mass extinction event is known as the Great Dying.

The culprit was, once again, environmental change. An enormous volcanic event in an already hot, dry climate led to a massive increase in carbon dioxide, and as ice sheets melted, methane escaped into the atmosphere, adding to the problem. These greenhouse gases led to the creation of anoxic conditions in marine habitats once more.

4. END-TRIASSIC EXTINCTION—200 MILLION YEARS AGO

After the Great Dying, it took approximately 20 million years for the Earth to recover. Unfortunately, soon after the Earth returned to its previous level of diversity, the next mass extinction came along and nearly wiped out the dinosaurs just as they were getting started. But it was the mammal groups who really suffered this time around, along with large amphibians: 76 to 84 percent of all species died out. The culprit may have once again been volcanic activity.

But dinosaurs managed to recover remarkably well, becoming the dominant creatures on the planet after this particular extinction event. And so they might well have remained, if it wasn’t for what happened next …

5. END-CRETACEOUS MASS EXTINCTION—66 MILLION YEARS AGO

This is the event we all know about. Many experts theorize that a large asteroid hit the Earth and contributed to rapid environmental changes. Sea levels plummeted, volcanic activity threw ash and poisonous gases into the air, and 71 to 81 percent of all species died. All non-avian dinosaurs perished, leaving the way clear for the small mammals that managed to survive.

BONUS: HOLOCENE EXTINCTION—10,000 BCE to ONGOING

And here we are today, having evolved from those small mammals. Are we in the grip of the sixth mass extinction of life on our planet? It's unclear how many species we're losing annually—one widely cited estimate is 140,000 species per year [PDF]—but it’s difficult to be sure of the size of the problem, as less than 3 percent of species on the planet are thought to have been formally assessed for risk.

The growth of humanity may be causing a loss of biodiversity, but the good news is that we have developed to the point where we might be able to do something about our own impact on the planet. We’re already aware of the problem—and there might even still be time to fix it.

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iStock // Ekaterina Minaeva
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technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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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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iStock
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Weird
Creative Bar Owners in India Build Maze to Skirt New Liquor Laws
June 20, 2017
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iStock

Facing a complicated legal maze, a bar in the southern Indian state of Kerala decided to construct a real one to stay in business, according to The Times of India. Aiswarya Bar, a watering hole that sits around 500 feet from a national highway, was threatened in 2016 after India's Supreme Court banned alcohol sales within 1640 feet of state and country-wide expressways to curb drunk driving. Instead of moving or ceasing operation, Aiswarya Bar's proprietors got creative: They used prefabricated concrete to construct a convoluted pathway outside the entrance, which more than tripled the distance from car to bar.

Aiswarya Bar's unorthodox solution technically adhered to the law, so members of the State Excise Administration—which regulates commodities including alcohol—initially seemed to accept the plan.

"We do [not] measure the aerial distance but only the walking distance," a representative told The Times of India. "However, they will be fined for altering the entrance."

Follow-up reports, though, indicate that the bar isn't in the clear quite yet. Other officials reportedly want to measure the distance between the bar and the highway, and not the length of the road to the bar itself.

Amid all the bureaucratic drama, Aiswarya Bar has gained global fame for both metaphorically and literally circumnavigating the law. But as a whole, liquor-serving establishments in India are facing tough times: As Quartz reports, the alcohol ban—which ordered bars, hotels, and pubs along highways to cancel their liquor licenses by April 1, 2017—has resulted in heavy financial losses, and the estimated loss of over 1 million jobs. Aiswarya Bar's owner, who until recently operated as many as nine local bars, is just one of many afflicted entrepreneurs.

Some state governments, which receive a large portion of their total revenue from liquor sales, are now attempting to downgrade the status of their state and national highways. To continue selling liquor in roadside establishments, they're rechristening thoroughfares as "urban roads," "district roads," and "local authority roads." So far, the jury's still out on whether Kerala—the notoriously heavy-drinking state in which Aiswarya Bar is located—will become one of them.

[h/t The Times of India]

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