While ants have a reputation for being intensely hard workers, previously published research has actually shown that at any given time, more than one-third of the ants in any given colony spend most of their time doing absolutely nothing – and now scientists think they know why.

In 2015, researchers from the University of Arizona found that approximately 40% of the ants in observed groups were almost totally inactive while their colleagues worked tirelessly to complete tasks essential to the colony’s survival. Further study revealed that these ants were not just being lazy – inactivity was their “specialization,” like how some ants foraged or built nests.

“Interestingly, we found laziness to be a behavior in itself,” Daniel Charbonneau, a grad student in the university’s Entomology and Insect Science department and one of the author of the 2015 paper, said at the time in a statement. At the time, however, the reason for this behavior remained unknown. Now, however, he and his colleagues believe that they’ve solved the mystery.

Writing in a recent edition of the journal PLOS One, Charbonneau, his professor (and co-author of the original study) Anna Dornhaus and Takao Sasaki from the University of Oxford explained that these so-called lazy ants are actually a reserve workforce that step in and pick up the slack if active workers need to be replaced. To borrow a sports analogy, they’re bench players.

“Serving as a replacement workforce is a long-held suspicion about the function of ‘lazy’ ants, but it was just an assumption, and never had been empirically confirmed,” Dornhaus noted last week in a statement. So she and her colleagues conducted experiments to put this notion to the test.

Removed ‘bench players’ are not replaced, researchers found

While observing a colony of ants belonging to the species Temnothorax rugatulus, Charbonneau and his co-authors identified and removed the ants that represented the top 20% of the workforce – those ants deemed to be the most active – to see how the inactive workers would respond.

Within one week, they found that these “bench players” stepped up and took over the roles that had been vacated by the ants that were no missing. These ants increased their levels of activity to match those of the lost workers, and the colony went about business as usual, they explained.

Charbonneau said that the ants being monitored were marked with paint on their head, thorax and abdomen so that they could be tracked in recorded  video footage. Since they studied these ants in the wild, he said that they did not know “how quickly their populations turn over in their natural habitat.” But, he added, “it doesn’t take much for a colony to lose a bunch of workers.”

In a separate experiment, Charbonneau and Dornhaus removed the least active 20% of the ants and found that, unlike the hardest workers, these ants were not replaced. In other works, ants that were busy building or foraging were not removed from those tasks to replace lost members of the inactive workforce.

“My speculation is this: Since young workers start out as the most vulnerable members of the colony, it makes sense for them to lay low and be inactive,” said Charbonneau. “And because their ovaries are the most active, they produce eggs, and while they’re doing that, they might as well store food. When the colony loses workers, it makes sense to replace them with those ants that are not already busy pursuing other tasks.”

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Image credit: Jen Fogarty/(C) AntWeb.org

For the first time, a scientist has found concrete evidence supporting a old tale by famed German naturalist Alexander von Humboldt in which he described electric eels leaping up from the water to attack horses – and the author of the new study put his own body on the line to do so.

That brave (or foolish, depending upon your perspective) man was Ken Catania, a neurobiologist at Vanderbilt University who reached into a tank containing a small electric eel 10 times in order to obtain accurate measurements of the circuit connecting created by eel, body part and water.

As the university said in a statement, the measurements allowed Catania “to solve an equation he can extrapolate to measure the power released by bigger eels,” some of which can be up to 8 feet in size or longer. His findings also support von Humboldt’s story, the New York Times added.

As Catania explained in a previous study, von Humboldt purportedly observed electric eels leap from the water to attack horses, pressing themselves against the horses’ legs while zapping them. Once the eels had exhausted their current, they could be safely collected, he said. While this tale has persisted, the behavior had not been seen again by scientists for more than two centuries.

In 2016, Catania reported finding “a defensive eel behavior that supports Humboldt’s account.” He saw an eel leap from the water and press its chin against an apparent threat while discharging high-voltage energy – behavior that would allow the eel to defend itself during the Amazon dry season, he explained in the Proceedings of the Natural Academy of Sciences (PNAS).

Large eels ‘more powerful’ than ‘a law enforcement Taser’

Now, as NPR reported on Thursday, the Vanderbilt neurobiologist has taken his research to the next level – measuring the electric potential of these eel as part of an August study  and allowing the creatures to actually shock his arm in order to see what their discharge actually feels like.

In the journal Current Biology, Catania revealed that the small eel delivered a current that peaked at about 40 to 50 milliamps, but his calculations indicate that a larger one would pack far more of a punch. Such a shock, he told NPR, would be “much more powerful… and [come] at a pulse rate that is higher than the pulse rate given off by a law enforcement Taser.”

Based on his current and previous work, Catania found that eels use this ability to capture prey or to protect itself from perceived threats. They disable or paralyze their prey by delivering current through the water, and wrap around larger creatures in order to shock them directly by forming a circuit. He first observed this behavior while trying to remove them with a metal-handled net.

“Electric eels, in my experience, had never done something like that where they come out of the water, and they did it in a very directed way,” he explained to NPR, adding that he heard their electrical output over a speaker. “I knew that when they were attacking the net in this way, they were simultaneously giving off a high voltage discharge. That clue led me to think, ‘Well, maybe this is sort of a defensive behavior.’”

Study finds that eels can remotely control victims’ nervous system

“As the eel came up out of the water, the voltage that I recorded increased in proportion to height. The higher they got, the higher the voltage and that suggested why they might be doing this,” Catania added. So, naturally, he decided to find out what would happen when the eel came into contact with a living animal – specifically, him.

He allowed an eel approximately one foot in size to zap his arm while he held onto a device that would measure the strength of the creature’s current. He told NPR that he was not worried about becoming injured, noting “if you work around electric eels a lot, occasionally you’re going to get shocked anyway. so I kind of knew what I was in for.”

The sensation was similar to touching a hot stove or an electric fence, he told the Times, and it even caused him to reflexively withdraw his arm from the water. “The fact that there’s an animal out there that can remotely control your nervous system, I think is a pretty amazing thing.”

While the experience was most likely not the most pleasant one in the world, Catania told NPR that the research was informative. “It does allow us now to think about and make some pretty reasonable estimates about, ‘Given an eel of size X and water resistance of a known resistance, how much power would one of these eels be able to divert to a human being that was standing in the water?’”

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Image credit: Vanderbilt University

Traces of DNA discovered in soil samples collected from warm caves located beneath the ice of Antarctica suggest that the region may be home to never-before-seen plant and animal species, a new study published earlier this week in the journal Polar Biology has revealed.

According to BBC News, a team of researchers from the Australian National University (ANU) in Canberra and the University of Waikato in New Zealand discovered “intriguing traces of DNA from mosses, algae and small animals” in caves located near an active volcano on Ross Island.

Steam originating from that volcano, Mount Erebus, created the caves by heating and hollowing out the ice, the British media outlet explained. In fact, as lead researcher Dr. Ceridwen Fraser of ANU noted, the caves “can be really warm – up to 25 degrees Celsius in some caves. You could wear a T-shirt in there and be pretty comfortable.”

The region also appears to be comfortable to other types of species as well, as Dr. Fraser and her colleagues discovered DNA in soil samples collected from those caves. While the majority of the DNA resembles that of plants and animals found in other parts of Antarctica, some of the genetic sequences could not be completely identified using forensic analysis.

“The results from this study give us a tantalizing glimpse of what might live beneath the ice in Antarctica,” Dr. Fraser said in a statement. In fact, she added, “there might even be new species of animals and plants” waiting to be discovered in these warm, subglacial caverns.

New species of plants and animals may inhabit these caves

As an active volcano, Mount Erebus has hollowed out an extensive cave system on Ross Island, the researchers explained, creating a geothermal region which could be home to a “microrefugia” or a small area inhabited by relict plant or animal species that have managed to survive.

However, as co-author Laurie Connell from the University of Maine emphasized, the discovery of these yet-unidentified traces of DNA does not conclusively prove that the caves are currently home to plants or animals. “The next steps,” she said, “will be to take a closer look at the caves and search for living organisms. If they exist, it opens the door to an exciting new world.”

The scientists have good reason to be hopeful, as University of Waikato professor Craig Cary told BBC News, as previous research revealed the existence of a wide array of bacteria and fungi living in volcanic caves in Antarctica. “The findings from this new study suggest there might be higher plants and animals as well,” he added.

While that possibility still needs to be verified, the authors believe that their discovery provides evidence to support the possibility that geothermal areas, including subglacial ecosystems, could cultivate biodiversity in icy regions such as Antarctica. Furthermore, since Antarctica is home to many volcanoes, there could well be several other sub-glacial cave systems located across the continent.

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Image credit: : Eli Duke/Flickr

One of the world’s most endangered mammals uses an rudimentary (and highly unusual) brand of democracy when attempting to decide whether or not to go on a hunt: they come together in a social gathering and cast their votes by sneezing, according to newly-published research.

Writing in the journal Proceedings of the Royal Society B, researchers from Swansea University, the University of New South Wales and Brown University explained that African wild dogs held so-called “social rallies” and used sneezing as a “quorum” when deciding if they should hunt.

As BBC News reported on Wednesday, the study authors observed the behavior in wild dogs at the Botswana Predator Conservation Trust, recording the details of 68 individual gatherings and noticing that the higher number of sneezes there were, the more likely the pack was to hunt.

Previously, the British media outlet noted, experts believed that the creatures were sneezing just to clear their airways. However, the new research demonstrates that it serves as for the wild dogs to cast their vote in favor of resuming their pursuit of food following the gatherings, which came at the end of a brief rest period. Such behavior has never before been observed in a species.

“The dogs were sneezing while preparing to go,” Dr. Neil Jordan, senior author of the study as well as a research fellow at the UNSW Centre for Ecosystem Science, said in a statement. “The more sneezes that occurred, the more likely it was that the pack moved off and started hunting. The sneeze acts like a type of voting system.”

Not all votes carry the same amount of weight, however

As the New York Times pointed out, other species use similar methods to express their desire to move on as a group – for example, gorillas use grunts and honeybees make a piping sound – but African wild dogs are the first species observed using sneezes as part of a democratic process.

The African wild dogs tended to hold their vote during the “social rallies,” which are energetic greeting periods that follow a rest period, Dr. Jordan and his colleagues said. However, they also found that some votes carried more weight when it came to the decision-making process.

“We found that when the dominant male and female were involved in the rally, the pack only had to sneeze a few times before they would move off,” explained first author Reena Walker, a zoologist at Brown University. “However, if the dominant pair were not engaged, more sneezes were needed – approximately 10 – before the pack would move off.”

“The sneezes act as a type of quorum, and the sneezes have to reach a certain threshold before the group changes activity,” added co-author Dr. Andrew King of Swansea University. “Quorums are also used by other social carnivores… but our finding that the quorum number of sneezes changes, based on who’s involved in the rally, indicates each dog’s vote is not equal.”

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Image credit: Andrew King

The mosquito-borne Zika virus has been feared because of the damage it can do to the brains of developing fetuses, but a new study published this week in the Journal of Experimental Medicine has discovered that the pathogen could actually be used to treat brain cancer in adults.

According to BBC News, researchers from the Cleveland Clinic and the Washington University School of Medicine in St. Louis have found that injecting the Zika virus into adult mice suffering from a form of brain cancer caused tumors to shrink without damaging other cells.

As the study authors explained to the St. Louis Post-Dispatch, Zika is harmful to unborn children because it targets stem cells in their still-developing brains. However, adult brains have far fewer stem cells, and they can be resistant to chemotherapy in patients suffering from a specific type of aggressive brain cancer known as glioblastoma.

Glioblastoma is the most common form of brain cancer, the researchers noted in a statement. In the US, roughly 12,000 people are diagnosed with the disease each year. In most cases, it proves fatal within one year of diagnosis, as affected stem cells often prove resistant to traditional forms of treatment (including chemotherapy), leading to a recurrence within six months.

“We showed that Zika virus can kill the kind of glioblastoma cells that tend to be resistant to current treatments and lead to death,” said Dr. Michael S. Diamond, a professor of medicine at Washington University and co-senior author of the new study. The breakthrough could one day provide a new treatment option for those suffering from the disease.

Safer, less potent version currently be testing in the lab

Dr. Diamond and his colleagues decided to test whether or not Zika’s tendency to attack stem cells in unborn babies could be weaponized against glioblastoma, testing its effectiveness in both living mice and in donated samples of human brain tissue, according to BBC News reports.

The infected tumors with one of two strains of Zika, and found that the virus spread through the tumor and killed cancer-infected stem cells while avoiding other cells, suggesting that Zika could be used to complement chemotherapy and other treatments. Furthermore, they reported that mice with brain tumors who were injected with Zika virus experienced significant shrinkage of tumors in just two weeks and survived longer than those injected with a saltwater placebo.

As Live Science noted, the use of Zika to treat brain tumors in humans remains a long way off, as additional research is needed to prove that it can be both safe and effective. The research team is working to genetically modify the virus to make it weaker and less likely to cause disease, the website noted, and early experiments show that this mutated strain can still effectively target and eliminate glioblastoma-infected stem cells in vitro, although it was said to be less potent.

“We’re going to introduce additional mutations to sensitize the virus even more to the innate immune response and prevent the infection from spreading,” said Dr. Diamond, who is also a professor of pathology and immunology. “Once we add a few more changes, I think it’s going to be impossible for the virus to overcome them and cause disease.”

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Image credit: (Jeffrey Arguedas/EFE/Zuma Press/TNS)

Long before modern man discovered the first glue, Neanderthals were using tar made from tree bark as an adhesive to craft weapons and other tools, according to a new study led by researchers from the Netherlands and published in a recent edition of the journal Scientific Reports.

In fact, as Ars Technica explained, lead investigator Paul Kozowyk, an archaeologist at Leiden University, and his colleagues found that Neanderthals were distilling tar for use in various tools as far back as 200,000 years ago, or 150,000 years before the first Homo sapiens even arrived in Western Europe!

According to Seeker, Kozowyk’s team analyzed archaeological evidence and conducted a series of experiments before determining that these archaic humans were able to invent tar and use it as an adhesive to affix handles to bone or stone tools, as well as to create improved spears and other types of weapons used for hunting.

The question is: how did they manage to pull off such a feat? After all, as Ars Technica pointed out, modern methods of tar production require it to be distilled at temperatures of 340 degrees to 370 degrees Celsius in a ceramic vessel – a difficult feat for the Neanderthals, given that ceramic was not even invented until approximately 20,000 years ago.

Based on their analysis, Kozowyk and his colleagues determined that they likely used a method known as dry distillation to create tar. This method, Popular Mechanics explained,  would have involved placing oak or birch bark into a fire to generate gases that would condense into tar.

Three possible techniques could have produced the adhesive

Even so, the Neanderthals still would have required some type of container in which to collect the gases and hold the tar, the publication added. The researchers tested various techniques using only the tools and technology that the ancient hominids would have possessed, and determined that there were three possible ways in which such a feat could have been accomplished.

The first possible technique, the “ash mound” method, involved heating bark under a pile of ash and embers, then gathering the emissions in a birch bowl. The second possible technique, the “pit roll” method, involved inserting a roll of bark into a narrow pit, then lighting the top on fire. This would have caused tar to drip onto a rock located on the bottom of the pit.

Finally, the third possible technique – the “raised structure” method – would have involved using a bowl made of birch. The bowl would have been placed in a shallow pit and covered over with a screen made from green willow wood, the researchers explained. The bark would have then been placed on top of the screen, buried and set in fire, slowly burning the bark and creating tar.

Kozowyk’s team reported that any of these methods would have produced a few grams of tar, even if the temperatures dipped below 200 degrees Celsius, and would not have required ceramic containers. Furthermore, they surmise that Neanderthals may have created tar by accident at first, then realizing its usefulness after touching it and becoming aware that it was sticky.

“It’s possible that all three methods we tested, or even some different methods, were used depending on the needs or requirements at the time… My personal favorite is the pit roll method, because it’s simple, but still produced reasonable quantities of tar,” Kozowyk said in an interview with Seeker. While tar was eventually used for many purposes, he added, it is “unlikely” that the Neanderthals used it for anything other than tool fabrication.

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Image credit: Paul Kozowyk