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On Sticking Your Arm Into an Underwater Cavern and Hoping a Catfish Bites You

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Jessica Rinaldi/Reuters/Landov

Lincoln Sadler eyes one of his favorite fishing spots, Great Rock, from a distance, but times his approach around an oncoming boat so as not to reveal the rock’s secret location. He has already hiked two miles in the boiling heat of an August North Carolina day followed by two miles of swimming and wading in the Pee Dee River.

Lincoln can wait a moment longer.

He reaches below the water and extends his arm into a dark cavern under the boulder. Enthusiastically wiggling his fingers in a dark underwater hole, Lincoln hopes a catfish bites him. Once Lincoln’s fingers are in the catfish’s mouth, he jerks the beast to the surface.

Near the Arkansas-Oklahoma border where I’m from, we call this noodling. In the Carolinas, the term is hand grabbling. Either way, it ends in a Greco-Roman grappling match where noodlers across the South, like Lincoln, wrestle very large catfish from their underwater holes. But this fishing story started long before Lincoln Sadler began his pilgrimage to Great Rock that August morning.

In the Beginning

Fifty million years ago, when bats, rodents, and elephants were also getting their start, large catfish species began diverging from their smaller brethren. Today, of the 49 catfish species in North America, 34 would not stretch across a dinner plate. Those 7 species of catfish prized by noodlers are the blue and channel catfish, and the flatheads. The latter can reach lengths of five and half feet. Work by Michael and Lotta Harman suggest these three species originated 35-40 million years after the original split between the large and small catfish, making them among the oldest of living catfishes.

Fast forward 11-15 million years and Lincoln is catching his largest catfish, 60 pounds, at Lost Rock, another of his secret locations on the Pee Dee. Lincoln’s prize catch is just 3.2 ounces light of the record largest catfish taken by Chad Lamb a few years later during the famous Okie Noodling Tournament.

Serving as human bait and wrestling catfish in the murky waters of the South may not seem efficient, but one study found that noodlers in the Tallahatchie River average catches of catfish 2.5 feet in length, nearly double that of traditional anglers. Ironically, if not for Lincoln and other noodlers, large size in catfish would prevent them from becoming dinner for a would-be predator.

In 1973, Jerry T. Krummrich, a masters student at Southern Illinois, investigated this by stocking experimental ponds with channel catfish and their predator, large-mouth bass. Krummrich determined that a channel cat must be 7-8 inches in length to avoid predation. Thus, the 49 species of catfish smaller than this would face tough times in many waters. This may be why the largest species of catfish also have the largest natural geographic ranges. The blue catfish is found from South Dakota to southern Mexico, the channel catfish from Mexico City to Manitoba, and the flathead from Mexico City to Minnesota. Compare this to one of the smallest catfish, the Ozark Matdom, measuring just over 4 inches in length. This catfish is found, as the name would suggest, exclusively in the Ozark Mountains.

There may be another reason why large catfish are geographically dispersed. Large fishes produce large clutches of eggs. While eventually yielding more offspring to geographically scatter, these large egg masses also attract predators. To protect against this, female catfish spawn in sheltered hollows with small entrances. Big underwater hollows with small openings, ideal nurseries for large catfish, are also favored by Lincoln and other noodlers. As with size itself, what would be typically evolutionarily favorable for a large catfish also makes it an easy target for a fish fry by noodlers.

You Are (Smarter Than) What You Eat

A twist of fate also produced another disadvantage for catfish. Along the Pee Dee River, Lincoln has identified a dozen rocks that are ideal for noodling. Among noodlers from the Carolinas to Oklahoma, these spots remain heavily guarded secrets. No flags or markers identify the rocks on the Pee Dee, just names, like Lost Rock and Great Rock, stored in the brains of Lincoln and his cohort.

Our large brains, that very trait that allows assessing habitat preferences for catfish or remembering locations of rocks along a river, require special nutrition. Specifically for our brain development, we need a significant amount of long-chain polyunsaturated lipids. Dr. Leigh Broadhurst does not believe it is coincidence that 3 million years ago our ancient ancestors arose in the East African Rift Valley, an area with many enormous lakes ripe with fish rich in these specific lipids.

David Braun and others found the earliest definitive evidence of this idea, a 1.95 million year old fossil site in East Turkana, Kenya, containing the butchered remains of aquatic animals. Today, fishermen benefit and catfish suffer from our million-year-old affinity for the fish course.

Increased brain size allowed not only for the development of memory and learning, but more complex communication and social interactions — and noodling is not a solitary recreational activity. As Lincoln states, “I never go by myself. Three is a minimum. If I get my arm caught in a hole, I need one person to run for help, and one person to hold my other hand.”

Sometimes, Lincoln’s group can swell to 17 people, including his brother and another Carolina noodling legend, Terry Sharp, who introduced Lincoln to noodling in 1998. Experience and social groups are key for noodlers and fishing success. For a masters thesis, Susan Baker of Mississippi State University surveyed hundreds of anglers throughout the South and found that noodlers formed stronger social connections and possessed more angling experience than traditional anglers.

But a noodler needs more than keen intellect and trustworthy friends. A noodler needs sheer bravado. Lincoln says that only about 1 in 30 men he takes out will stick their whole arm in a dark underwater hole. “They don’t cowboy up and just alligator arm it,” he says. In other words, many are too tentative, reaching in a short distance, their arms mimicking the short, squatty arms of alligators. So perhaps it's not shocking that a study found noodling is tied to masculine identity among Missouri noodlers. If, as Dr. Meghan Provost has shown, fertile women have a strong preference for men who strut in a masculine manner, imagine what landing a 100-pound catfish does for your image.

Is This Legal?

Wrestling a giant catfish to impress your friends, attract females, or simply for a large fish fry is not without controversy. Noodling is legal in just five states. In Texas, noodling is currently illegal but a bill to change this was approved by the Texas senate and house last summer. Why would noodling be illegal compared to other forms of angling? Fisheries and biologists voice concerns about the possible negative impacts on catfish populations, because noodling season in Mississippi specifically coincides with catfish spawning in the summer. Nevertheless, research indicates noodling does not negatively impact catfish populations in Mississippi or in Oklahoma due to limited success of noodlers in muddy waters and rapid currents.

And there's another reason why there may be no impact. Ultimately, few people want to “cowboy up” and shove their hands into the mouths of giant catfish.

Dr. Craig McClain is an expert on the science of body size in animals. His work has been featured in Miller-McCune, Cosmos, Science Illustrated, Wired, io9, and American Scientist. He is currently the assistant director of the National Science Foundation’s National Evolutionary Synthesis Center in Durham, North Carolina.

You can find Craig on Twitter @DrCraigMc, blogging at, or at

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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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One Bite From This Tick Can Make You Allergic to Meat
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We like to believe that there’s no such thing as a bad organism, that every creature must have its place in the world. But ticks are really making that difficult. As if Lyme disease wasn't bad enough, scientists say some ticks carry a pathogen that causes a sudden and dangerous allergy to meat. Yes, meat.

The Lone Star tick (Amblyomma americanum) mostly looks like your average tick, with a tiny head and a big fat behind, except the adult female has a Texas-shaped spot on its back—thus the name.

Unlike other American ticks, the Lone Star feeds on humans at every stage of its life cycle. Even the larvae want our blood. You can’t get Lyme disease from the Lone Star tick, but you can get something even more mysterious: the inability to safely consume a bacon cheeseburger.

"The weird thing about [this reaction] is it can occur within three to 10 or 12 hours, so patients have no idea what prompted their allergic reactions," allergist Ronald Saff, of the Florida State University College of Medicine, told Business Insider.

What prompted them was STARI, or southern tick-associated rash illness. People with STARI may develop a circular rash like the one commonly seen in Lyme disease. They may feel achy, fatigued, and fevered. And their next meal could make them very, very sick.

Saff now sees at least one patient per week with STARI and a sensitivity to galactose-alpha-1, 3-galactose—more commonly known as alpha-gal—a sugar molecule found in mammal tissue like pork, beef, and lamb. Several hours after eating, patients’ immune systems overreact to alpha-gal, with symptoms ranging from an itchy rash to throat swelling.

Even worse, the more times a person is bitten, the more likely it becomes that they will develop this dangerous allergy.

The tick’s range currently covers the southern, eastern, and south-central U.S., but even that is changing. "We expect with warming temperatures, the tick is going to slowly make its way northward and westward and cause more problems than they're already causing," Saff said. We've already seen that occur with the deer ticks that cause Lyme disease, and 2017 is projected to be an especially bad year.

There’s so much we don’t understand about alpha-gal sensitivity. Scientists don’t know why it happens, how to treat it, or if it's permanent. All they can do is advise us to be vigilant and follow basic tick-avoidance practices.

[h/t Business Insider]