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Study Shows Some Worker Ants Don’t Work At All

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Last summer, researchers at the University of Illinois revealed that most bees aren’t as busy as we give them credit for, and a small group of workers handles the bulk of the labor in a hive. Now, another research team has taken the famously industrious ant down a peg, showing that many ants don’t do their fair share of work—or any work at all.

In many types of social insect, entomologists have found workers that really don’t do much. In some cases, researchers report that half or more of the bugs in a colony are inactive and spend their time just hanging around. Daniel Charbonneau and Anna Dornhaus are biologists at the University of Arizona’s Social Insect Lab, where they primarily study Temnothorax rugatulus, a species of ant found throughout the Western U.S. and Canada. They’ve seen plenty of lazy ants first-hand during their research, but it wasn’t clear whether these ants were consistently inactive or simply taking a break or working in shifts. In a new study, the pair shows that these ants are dedicated to being bums, and that might actually be their job.

The scientists collected five colonies of the ants around Tucson and, using a microscope and thin wire, painstakingly marked 250 workers with unique combinations of paint spots so they could be identified and tracked. They let the ants go about their business for three weeks and recorded them on video for a few minutes at regular intervals. They then went through their footage and recorded what each of the tagged ants was doing.

They found that around 25 percent of the ants were inactive throughout the study. Differences in rest schedules and work shifts didn’t explain the difference, because no matter what time the videos were taken, the same ants were still standing around. These ants were so consistent at doing nothing, the researchers say, that it looks like some workers “effectively specialize in ‘inactivity’” the same way others specialize in foraging for food or tending to the colony’s larvae.

Why do so many ants dedicate themselves to doing so little? Charbonneau and Dornhaus’ study didn’t try to figure that out, but they suggest plenty of ideas that can be tested. First, they say, the inactive ants may have a job to do that they just didn’t see during their short window of ant-watching, maybe a task that’s only performed at a certain time of year or at a specific point in the ants’ life cycle. These particular ants could have also been too young to start working, or too old to continue working and were living the easy life of insect retirement.

They might also be a kind of reserve work force that springs into action when other workers die or the workload in the colony suddenly increases, though other studies testing that idea with different insects found little support for it and showed that when more labor is needed, the ants that are already working just work harder and increase their activity.

Another possibility is that the lazy ants are “behaviorally idle” but not “functionally idle,” and have jobs that don’t require much movement or look like work, such as acting as live feeding stations and regurgitating food for other ants when needed, or relaying chemical messages around the nest.

Finally, the researchers say these ants might just be selfish, shirking their assigned duties so they can conserve energy and minimize their exposure to danger.

“Ultimately, the question of why colonies would produce so many inactive workers, in spite of potentially high production and maintenance costs, is still very much a mystery,” the scientists write, one that will be solved only with more experiments testing all these ideas and others. For now, they urge other ant researchers to not write inactive ants off as inefficient or unimportant just because they don’t do active tasks. Lazy ants are a distinct group with their own unique set of behaviors and characteristics, they write, and ignoring them and their main “activity” in certain studies may skew our understanding of ants’ social structure and division of labor.

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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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200 Health Experts Call for Ban on Two Antibacterial Chemicals
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In September 2016, the U.S. Food and Drug Administration (FDA) issued a ban on antibacterial soap and body wash. But a large collective of scientists and medical professionals says the agency should have done more to stop the spread of harmful chemicals into our bodies and environment, most notably the antimicrobials triclosan and triclocarban. They published their recommendations in the journal Environmental Health Perspectives.

The 2016 report from the FDA concluded that 19 of the most commonly used antimicrobial ingredients are no more effective than ordinary soap and water, and forbade their use in soap and body wash.

"Customers may think added antimicrobials are a way to reduce infections, but in most products there is no evidence that they do," Ted Schettler, science director of the Science and Environmental Health Network, said in a statement.

Studies have shown that these chemicals may actually do more harm than good. They don't keep us from getting sick, but they can contribute to the development of antibiotic-resistant bacteria, also known as superbugs. Triclosan and triclocarban can also damage our hormones and immune systems.

And while they may no longer be appearing on our bathroom sinks or shower shelves, they're still all around us. They've leached into the environment from years of use. They're also still being added to a staggering array of consumer products, as companies create "antibacterial" clothing, toys, yoga mats, paint, food storage containers, electronics, doorknobs, and countertops.

The authors of the new consensus statement say it's time for that to stop.

"We must develop better alternatives and prevent unneeded exposures to antimicrobial chemicals," Rolf Haden of the University of Arizona said in the statement. Haden researches where mass-produced chemicals wind up in the environment.

The statement notes that many manufacturers have simply replaced the banned chemicals with others. "I was happy that the FDA finally acted to remove these chemicals from soaps," said Arlene Blum, executive director of the Green Science Policy Institute. "But I was dismayed to discover at my local drugstore that most products now contain substitutes that may be worse."

Blum, Haden, Schettler, and their colleagues "urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers" to avoid antimicrobial chemicals outside of medical settings. "Where antimicrobials are necessary," they write, we should "use safer alternatives that are not persistent and pose no risk to humans or ecosystems."

They recommend that manufacturers label any products containing antimicrobial chemicals so that consumers can avoid them, and they call for further research into the impacts of these compounds on us and our planet.