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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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Good News, Dog Parents: You Can Teach Puppies as Well as Their Canine Moms Can
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If you’ve ever adopted a puppy, you probably know how frustrating it can be to teach your new family member the basic tenets of common decency, like not to pee on the carpet or tear up a whole roll of toilet paper.

In other areas, though, pups are rather impressive learners, capable of mimicking some human behaviors. In fact, for some tasks, they learn just as effectively from watching people as they do from watching other dogs, including their own mothers, a new study in Nature revealed.

Researchers from Hungary and the UK took 48 young puppies of various breeds and studied the conditions under which they can be taught to open a puzzle box containing food. The experiment revealed that the puppies were able to learn how to open the box regardless of whether the task was first demonstrated by a person, their mother, or an unfamiliar dog. In other words, not only are puppies capable of social learning, but they're able to learn tasks from humans they don't know—in this case, the experimenter.

However, researchers were surprised to learn that the puppies were more likely to learn how to open the box by watching an unfamiliar dog than by watching their own mothers. That may be because puppies spend more time looking at—and thus, learning from—an unfamiliar dog that intrigues them. This differs from other species such as kittens, which “learn to press a lever for food more rapidly from their mother than from an unfamiliar adult,” the study notes.

In addition, the puppies were able to perform the task again after a one-hour break, indicating that they had retained some memory of the learning experience.

The ability of dogs to learn from humans has been recorded in previous research. A 2015 study revealed that dogs learn better by demonstration (or the “do as I do” method) than training techniques that involve a system of punishments and rewards. The "do as I do" approach probably isn't the most practical method of teaching your pup to do its business outside, but if you already have an adult dog at home, your new puppy can follow the older dog's lead and learn by example.

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Michael Hutchinson
Spiders Can Fly Through the Air Using the Earth's Electric Field
A spider exhibiting ballooning behavior.
A spider exhibiting ballooning behavior.
Michael Hutchinson

Every so often, otherwise Earth-bound spiders take to the air. Ballooning spiders can travel hundreds of miles through the air (and, horrifyingly, rain down on unsuspecting towns). The common explanation for this phenomenon is that the spiders surf the wind on strands of silk, but there may be other forces at work, according to a new study spotted by The Atlantic.

In the research, published in Current Biology, University of Bristol scientists argue that Earth's atmospheric electricity allows spiders to become airborne even on windless days. To test their hypothesis, the researchers exposed spiders in the lab to electric fields similar to those naturally found in the atmosphere.

When the electric field was turned on, the spiders began to exhibit behavior associated with ballooning—they "tiptoed" on the ends of their legs, raised their abdomens, and released silk. Spiders only exhibit this behavior when ballooning. And when they did become airborne, the spiders’ altitude could be controlled by turning the electric field on and off. When the electric field was on, they rose through the air, but when it was off, they drifted downward.

This provides a potential explanation for why spiders take to the skies on certain days but not others, and how they can fly in calm, windless weather— something scientists have puzzled over since the early 19th century. (Even Darwin was flummoxed, calling it "inexplicable," The Atlantic notes.) However, the researchers note that these electric fields might not be totally necessary for ballooning—wind alone might work perfectly fine on some days, too. But understanding more about when and how spiders become airborne could help us predict when there will be large masses of arachnids flying through the skies (and hide).

[h/t The Atlantic]

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