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Jumping Beans’ Random Strategy Always Leads To Shade — Eventually




Given enough time, jumping beans will always find their way out of the sun.

Jumping beans, which are really seed pods with twitchy moth larvae inside, hop around in a way that — if they live long enough — is guaranteed to eventually land them in the shade, researchers report in a study to appear in January in Physical Review E.

When a jumping bean finds itself in a sunny spot where it might overheat and die, the moth larva will twitch to make the bean jump a short distance. “If I’m a bean and I exist outside of the shade,” says physicist Pasha Tabatabai of Seattle University, “all I want to know is what’s the eventual probability of finding shade?”

To determine how the creatures approach the problem, Tabatabai and Devon McKee — now a computer scientist at the University of California, Santa Cruz — tracked the jumps of beans placed on a warm surface. They discovered that each jump was in a random direction, with no correlation to the previous jumps. Mathematicians call this way of moving around a random walk (SN: 3/15/06).

While a random walk isn’t a quick way to travel, Tabatabai says, a creature using it to move on a surface, like the ground near a tree, will theoretically visit every place on the surface eventually. That means a random walking bean will always end up in the shade if it keeps it up long enough.

Picking a direction and repeatedly going that way would cover distance faster. “You’re certainly going to find shade fastest,” Tabatabai says — assuming you’re headed the right way. “But it’s also very likely that you’ll pick the wrong direction and never find shade.”

Random walks are slow, and many jumping beans don’t survive to find shade in real life. But, Tabatabai says, the strategy minimizes the odds that they will never escape the sun.


Honeybees Waggle To Communicate. But To Do It Well, They Need Dance Lessons





In a castaway test setup, groups of young honeybees figuring out how to forage on their own start waggle dancing spontaneously — but badly.

Waggling matters. A honeybee’s rump-shimmy runs and turning loops encode clues that help her colony mates fly to food she has found, sometimes kilometers away. However, five  colonies in the new test had no older sisters or half-sisters around as role models for getting the dance moves right.

Still, dances improved in some ways as the youngsters wiggled and looped day after day, reports behavioral ecologist James Nieh of the University of California, San Diego. But when waggling the clues for distance information, Apis mellifera without role models never did match the timing and coding in normal colonies where young bees practiced with older foragers before doing the main waggle themselves.

The youngsters-only colonies thus show that social learning, or the lack of it, matters for communicating by dance among honeybees, Nieh and an international team of colleagues say in the March 10 Science. Bee waggle dancing, a sort of language, turns out to be both innate and learned, like songbird or human communication.

The dance may appear simple in a diagram, but executing it on expanses of honeycomb cells gets challenging. Bees are “running forward at over one body length per second in the pitch black trying to keep the correct angle, surrounded by hundreds of bees that are crowding them,” Nieh says.

Beekeepers and biologists know that some kinds of bees can learn from others of their kind — some bumblebees even tried soccer (SN: 2/23/17). But when it comes to waggle dancing, “I think people have assumed it’s genetic,” Nieh says. That would make this fancy footwork more like the chatty but innate communications of cuttlefish color change, for instance. The lab bee-castaway experiments instead show a nonhuman example of “social learning for sophisticated communication,” Nieh says.

Testing for social learning took some elaborate beekeeping. At an apiary research center in Kunming, China, researchers put thousands of nearly grown-up honeybees (at what’s called the purple-eyed pupae stage) into incubators and then collected the brand-new winged adults when they emerged.

These youngsters went into five weirdly populated colonies of same-age worker newbies. Each colony got a queen, who would lay eggs but not leave the colony to forage. Food had to come from the young workforce, with no older, experienced foragers buzzing in and dancing the locations of flowers.

In waggle dancing, foraging bees have to master not only the moves but the obstacles of the honeycomb dance floor. A cell may be empty. “It’s just the edges to hang on to…. It would be easy to stumble,” Nieh says. Unlike commercial hives with manufactured uniform honeycomb cells, natural combs “are very irregular,” he says. “Along the edges, they get a bit crazy and rough.”

A honeybee that brings home food to her colony does a looping, waggling dance that tells her colony mates how to find the source. In the center, a bee with a green dot on her back is doing her first waggle dance as other bees crowd around. She’s already gotten to follow along with dances by other experienced foragers, so she makes fairly regular figure eights. Bees that don’t have such mentors don’t nail the dance moves as well, a new study shows. 

Dances on these treacherous surfaces encode the food’s direction in the angle a dancer waggles across the comb (measured relative to gravity). Duration of waggling bout gives a clue on how far away the bonanza is.

The five colonies of castaways were left to figure out dancing on their own, in contrast to five other colonies in the apiary with a natural mix. Early in the experiments, researchers recorded and analyzed the first dances of five bees from each hive.

Even in the mixed-age hives, the dancers didn’t get the angle perfect every time. The extremes in a set of six waggle runs might differ by a bit more than 30 degrees. The castaway hives, though, had far more trouble at first. Two of the five castaway dancers’ angles veered more than 50 degrees apart, and one poor bee strayed more than 60 degrees in six repeats.

Waggle dancing lets honeybees share news about where to find food. The honeybee marked with a purple dot that’s making irregular figure eight loops in the center did not have older, experienced foragers around to lead her in practice dances. As a result, her first dance is rough and other bees seem to be colliding with her as much as following her. A study comparing bees with and without dance mentors suggests that this sophisticated communication is a mix of innate and learned behavior.

As the castaways got more experience, they got better though. Repeating the test with the same marked bees a few weeks later near the end of their lives found them angling about as well as dancers in a normal hive.

What the castaways didn’t change much were dance features that encode distance to food. Researchers had set up the hives so that all would have the same experience of flying the distance to a feeder. Yet castaway bees persisted in dancing as if it were farther.

They gave more rump wags per waggle run (closer to five wags) than bees from mixed-age hives (more like 3.5 wags). The youngsters also took longer on each run.

Evidence like this foraging study is “indeed accumulating for the importance of learning (whether individual or social) in the complex behaviors of bees,” insect ecophysiologist Tamar Keasar of the University of Haifa in Israel says in an email. In her own work, she sees bees learning to extract food from complicated flowers. Bees aren’t, after all, just little automatons with wings.

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Scientists Have Mapped An Insect Brain In Greater Detail Than Ever Before





The wiring of one insect’s brain no longer contains much uncharted territory.

All of the nerve cells — and virtually every connection between them — in a larval fruit fly brain have now been mapped, researchers report in the March 10 Science. It’s the most complex whole brain wiring diagram yet created. 

Previously, just three organisms — a sea squirt and two types of worm — had their brain circuitry fully diagrammed to this resolution. But the brains of those creatures have only a few hundred neurons. The scientists who conducted the new study wanted to understand much more complicated brains.

Fruit flies (Drosophila melanogaster) share a wide range of behaviors with humans, including integrating sensory information and learning. Larvae perform nearly all the same actions as adult flies — except for some, like flying and mating — but have smaller brains, making data collection much faster (SN: 7/19/18).

The idea for this project came 12 years ago, says neuroscientist Marta Zlatic of the MRC Laboratory of Molecular Biology in Cambridge, England. At that time, she and her colleagues captured electron microscope images of the entire larval fruit fly brain. They then stitched those images together in a computer and manually traced each neuron to create a 3-D rendering of the cells. Finally, the team found the connections where information gets passed between the cells, and even determined the sending and receiving ends.

The researchers identified more than 3,000 neurons and about 550,000 connections, known as synapses.

This 3-D rendering of the larval fruit fly’s neurons was constructed from serial images captured with an electron microscope. Spheres represent each nerve cell body and the elongated tails are branches that send and receive information.

Neurons transmit information to one another in circuits. Exploring the neurons’ connectivity patterns — not just directly linked partners, but also the links of linked cells and so on — revealed 93 different types of neurons. The classes were consistent with preexisting groupings characterized by shape and function. And nearly 75 percent of the most well-connected neurons were tied to the brain’s learning center, indicating the importance of learning in animals.

The researchers hope that this work serves as a blueprint for fellow scientists studying brain circuitry. “Now we have a reference map,” Zlatic says.

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Bird Flu Can Jump To Mammals. Should We Worry?





An uncomfortable truth is that there is another influenza pandemic in humankind’s future. Whether it will be a relative of the lethal avian flu strain currently wreaking havoc in bird populations around the globe is anyone’s guess.

Because the virus, called H5N1, can be deadly to birds, mammals and people, researchers closely monitor reports of new cases. Worryingly, a new variant of H5N1 that emerged in 2020 has not only spread farther than ever before among birds, but has also spilled over into other animals, raising the specter of a human outbreak (SN: 12/12/22).

The variant was linked to a seal die-off in Maine last summer. In October, there was an H5N1 outbreak on a mink farm in Spain, researchers reported in January in Eurosurveillance. (It’s unclear how the mink were exposed, but the animals were fed poultry by-products.) Sea lions off the coast of Peru and wild bears, foxes and skunks, which prey upon or scavenge birds, in the United States and Europe have also tested positive for the virus.

Globally, hundreds of millions of domestic poultry have been culled or died from the new variant. It’s also likely that millions of wild birds have died, though few governmental agencies are counting, says Michelle Wille a viral ecologist at the University of Sydney who studies avian influenza. “This virus is catastrophic for bird populations.”

A handful of human cases have also been reported, though there’s no evidence that the virus is spreading among people. Of seven cases, six people recovered and one person from China died. In February, health officials in China reported an eighth case in a woman whose current condition is unknown.

What’s more, four of the reported human cases — including a U.S. case from Colorado and two workers linked to the Spanish mink farm — were in people who didn’t have any respiratory symptoms. That leaves open the possibility that those people were not truly infected. Instead, tests may have picked up viral contamination, say in the nose, that the people breathed in while handling infected birds.

The impossibility of predicting which avian influenza viruses might make the jump to people and spark an outbreak is in part related to knowledge gaps. These bird pathogens don’t typically easily infect or circulate among mammals including humans. And scientists don’t have a full grasp on how these viruses might need to change for human transmission to occur.

For now, it’s encouraging that so few people have gotten infected amid such a large outbreak among birds and other animals, says Marie Culhane, a food animal veterinarian at the University of Minnesota in St. Paul. Still, experts around the globe are diligently watching for any signs the virus may be evolving to spread more easily between people.

The good news is that flu drugs and vaccines that work against the virus already exist, Wille says. Compared with where the world was when the coronavirus behind the COVID-19 pandemic came on the scene, “we are already ahead of the game.”

How the virus would need to change to spread among people is a big unknown

This new iteration of bird flu is what’s called a highly pathogenic avian influenza, one that is particularly lethal for both domestic and wild birds. Aquatic birds such as ducks naturally carry avian flus with no or minor signs of infection. But when influenza viruses shuffle between poultry and waterfowl, variants with changes that make them lethal to birds can emerge and spread.

Avian viruses can be severe or even deadly for people. Since 2003, there have been 873 human cases of H5N1 infections reported to the World Health Organization. A little less than half of those people died. In February, an 11-year-old girl in Cambodia died after she developed severe pneumonia from an avian flu virus, the country’s first reported infection since 2014. Her father was also infected with the virus — a different variant than the one behind the widespread outbreak in birds —though he has not developed symptoms. It’s unknown how the two people were exposed.

Some of what scientists know about H5N1’s pandemic potential comes from controversial research on ferrets done more than a decade ago (SN: 6/21/13). Experiments showed that some changes to proteins that help the virus break into cells and make more copies of itself could help the virus travel through the air to infect ferrets, a common laboratory stand-in for humans in influenza research.    

While researchers know these mutations are important in lab settings, it’s still unclear how crucial those changes are in the real world, says Jonathan Runstadler, a disease ecologist and virologist at Tufts University’s Cummings School of Veterinary Medicine in North Grafton, Mass.

Viruses change constantly, but not all genetic tweaks work together. A change may help one version of the virus transmit better, while also hurting another variant and making it less likely to spread.

“We’re not sure how critical or how big a difference or how much to worry about those mutations when they happen in the wild,” Runstadler says. “Or when they happen five years down the road when there are other changes in the virus’s genetic background that are impacting those [original] mutations.”

That doesn’t stop researchers from trying to pinpoint specific changes. Runstadler and his team look for viruses in nature that have jumped into new animals and work backward to figure out which mutations were crucial. And virologist Louise Moncla says her lab is trying to develop ways to scan entire genetic blueprints of viruses from past outbreaks to look for signatures of a virus that can jump between different animal species.

“There’s a ton that we don’t know about avian influenza viruses and host switching,” says Moncla, of the University of Pennsylvania.

Genetic analyses of H5N1 circulating on the mink farm in Spain, for instance, revealed a change known to help the virus infect mice and mammalian cells grown in the lab. Such a change could make it easier for the virus to spread among mammals, including people. There could have been mink-to-mink transmission on the farm, the researchers concluded, but it remains unclear how much of a role that specific mutation played in the outbreak. 

It’s a numbers game for when influenza viruses with the ability to transmit among mammals might make the jump from birds, Runstadler says. “The more chances you give the virus to spill over and adapt, the higher the risk will be that one of those adaptations will be effective [at helping the virus spread among other animals] or take root and be a real problem.”

The ongoing outbreak is still a big problem for birds

Irrespective of our inability to forecast human’s future with H5N1, it’s clear that many species of birds — and some other animals that eat them — are dying now. And more species of birds are dying in this outbreak than previous ones, Culhane and Wille say.

“We have seen huge outbreaks in raptors and seabirds, which were never really affected before,” Wille says. It’s possible that genetic changes have helped the virus to spread more efficiently among birds than previous versions of H5N1, but that’s unknown. “There are a number of studies underway to try and figure it out,” Wille says.

Kooiker Teun de Vaal of the Netherlands uses a cotton swab to test one of his ducks.
Researchers and farmers around the world monitor cases of bird flu on commercial and backyard farms to keep track of deadly avian flus that could jeopardize flocks. Here, Kooiker Teun de Vaal of the Netherlands uses a cotton swab to test one of his ducks on January 12, 2022.SANDER KONING/ANP/AFP via Getty Images

Historically, these deadly avian flus have not been a persistent problem in the Americas, Moncla says. Sporadic outbreaks of H5N1 variants are typically limited to places such as parts of Asia, where the virus has circulated in birds since its emergence in the late 1990s, and northern Africa.

North America’s last big avian flu outbreak was in 2015, when experts detected more than 200 cases of a different bird flu virus in commercial and backyard poultry across the United States. The poultry industry culled more than 45 million birds to stop that virus’s spread, Culhane says. “But it didn’t go away from the rest of the world.”

The latest version of H5N1 arrived on North American shores from Europe in late 2021, first popping up in Canada in Newfoundland and Labrador. From there, it spread south into the United States, where so far tens of millions of domestic poultry have been culled to prevent transmission on farms where the virus has been detected. By December 2022, the virus had made it to South America. In Peru, tens of thousands of pelicans and more than 700 sea lions have died since mid-January.

It’s important to understand exactly how nonbird animals are getting exposed, Culhane says. Highly pathogenic avian influenzas infect every organ of a bird’s body. So, a fox chowing down on an infected bird is exposing its own mouth, nose and stomach to a lot of virus as it eats its meal.  

For now, experts are keeping an eye on infected animals to raise the alarm early if H5N1 starts transmitting among mammals.

“I do think that the mink outbreak, and then the sea lion outbreak, is a wake-up call,” Moncla says. “We should be doing our very best to implement all the science we can to try and understand what’s happening with these viruses so that if the situation does change, we are better prepared.”

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