Fancy flight tricks are a breeze for a new flying robot. Call it an acrobat.

Bat Bot, a lightweight flier with thin silicone wings stretched over a carbon fiber skeleton, can cruise, dive and bank turn just like its namesake, researchers report February 1 in Science Robotics.

Such a maneuverable machine could one day soar up the towering structures of a construction site, flying in and out of steel beams to help keep track of a building’s progress, study coauthor Seth Hutchinson, a roboticist at the University of Illinois at Urbana-Champaign, said in a news briefing January 31.
Other aerial robots, like some drones, aren’t so agile, relying on four whirling rotor blades to lift off the ground, Hutchinson said. These bots also have trouble flying in the wind, because they can exert force in only one direction, he said. Bat Bot’s flexible wings could make it a more versatile flier.

“Bat flight is the holy grail of aerial robotics,” said study coauthor Soon-Jo Chung, a Caltech aerospace engineer. Bats have more than 40 joints in their wings, which give the animals exquisite control over their flight maneuvers. Chung and colleagues re-created nine of the key joints, so their robot could flap its wings in sync, fold each wing independently and move each of its hind legs up and down. At 93 grams, with a wingspan of 47 centimeters, Bat Bot is roughly the size of an Egyptian fruit bat, Chung said.

An onboard computer and sensors let Bat Bot adjust its movements in midair. But the bot still needs a net to land: A crash could bust its electronics. Sticking the landing is the next step, the researchers said. They want Bat Bot to be able to perch — both right-side up and upside down.

Discoveries in a richly appointed 2,600-year-old burial chamber point to surprisingly close ties between Central Europe’s earliest cities and Mediterranean societies. Dated to 583 B.C., this grave also helps pin down when people inhabited what may have been the first city north of the Alps.

An array of fine jewelry, luxury goods and even a rare piece of horse armor found in the grave indicates that “there were craftsmen working in the early Celtic centers north of the Alps who learned their crafts south of the Alps,” says archaeologist Dirk Krausse of the Archaeological State Office of Baden-Württemberg, Germany.
Previous research has established that speakers of Celtic languages inhabited parts of Europe as early as 3,300 years ago. Celtic iron makers appeared in Central Europe by around 2,700 years ago — marking the beginning of that region’s Iron Age — and founded what’s now called the Hallstatt culture.

The grave and a smaller adjoining burial lie in a German cemetery situated across the Danube River from an early Iron Age hill fort called the Heuneburg. Along with yielding insights into long-distance trade and the timing of Europe’s first Iron Age cities, these graves provide the earliest evidence of Hallstatt people elaborately interring women and even children, Krausse and colleagues report in the February Antiquity.

“The main burial represents one of the oldest examples of an exceptionally rich female grave and serves as further testimony of the important social role of certain women in Hallstatt communities,” says archaeologist Manuel Fernández-Götz of the University of Edinburgh, who did not participate in the new study.
While surveying earthen mounds covering graves at the German site in 2005, Krausse’s team noticed a gold-plated bronze brooch fragment lying on the ground. An excavation revealed that the brooch came from the grave of a 2- to 4-year-old child whose skeleton was surrounded by gold and gold-plated jewelry.
It turned out that the child’s grave was an addition to a larger burial chamber. Because farming activity threatened the site, cranes were used in 2010 to hoist out the chamber and surrounding soil in a block weighing 80 metric tons. Researchers excavated the tomb at Krausse’s facility.

Planks of oak and silver fir formed the chamber. Comparisons of growth rings in the planks with previously dated tree rings in the region indicate that the tomb was built in 583 B.C. Previous excavations over the past decade had suggested that the Heuneburg and several other early Iron Age settlements in Germany and France were the first cities north of the Alps, but the grave provides the most precise date yet. Prior to this find, settlements dating to between 2,200 and 2,000 years ago have traditionally been considered the first Central European cities.

Inside the chamber, the team discovered a 30- to 40-year-old woman’s headless skeleton. Her lower jaw and skull were found at two other spots in the grave. Objects placed on and around the skeleton included gold, bronze, amber and jet jewelry and brooches. Decorative styles of some items showed Mediterranean influences. Researchers also found two pairs of boar tusks mounted on large pendants. Each pair of tusks curves around two bronze strips and bronze bells hanging from a smaller pendant.

Another woman’s skeleton and pieces of bronze jewelry rested in a corner of the chamber. It’s unclear whether both bodies were buried at the same time.

A decorated bronze sheet found near the second skeleton’s feet was a piece of armor, called a chamfron, that covered a horse’s forehead, the researchers say. Traces of plant netting and fur preserved on the inside surface of the sheet come from padding, they suspect. CT scans revealed remains of an iron horse bit at one end of the sheet, where it fit in the mouth.

This is the first chamfron found at a Hallstatt site. It resembles horse armor from around the same time found in several Mediterranean cultures, Krausse says.

“The tide is finally shifting” toward accepting links between early European Iron Age cities and societies south of the Alps, says anthropologist Bettina Arnold of the University of Wisconsin–Milwaukee. She suspects that, as at some other Iron Age graves, the elite woman’s burial chamber was looted or material was removed for ritual reasons shortly after interment. Such burials typically included a wagon and metal vessels, but these are missing in the woman’s spacious grave. “This grave is a puzzle, and Hallstatt culture is still enigmatic,” Arnold says.

High-energy ion collisions have produced the swirliest fluid ever discovered, in a state of matter that mimics the early universe.

To create the überwhirly liquid, scientists slammed gold ions together at velocities approaching the speed of light at Brookhaven National Laboratory in Upton, N.Y. Such collisions, performed in Brookhaven’s Relativistic Heavy Ion Collider, cook up an ultrahot fluid, re-creating the state of the universe millionths of a second after the Big Bang, before protons and neutrons had formed. In this fluid, known as a quark-gluon plasma, the constituents of protons and neutrons — quarks and gluons — intermingle freely (SN: 12/10/16, p. 9).

Scientists already knew that this fluid is the hottest ever produced in a laboratory, and that it has almost no viscosity. Now, physicists can add one more unusual property to the list. The quark-gluon plasma created in such collisions has an average vorticity — or swirliness — of about 9 billion trillion radians per second, researchers from the STAR Collaboration report online January 23 at arXiv.org. That’s vastly more than other known fluids. Even the core of a supercell tornado has a vorticity of only 0.1 radians per second.

To measure vorticity, the scientists studied a quantum mechanical property called spin from particles produced in the collision known as lambda baryons. The spin, an intrinsic type of angular momentum, tends to align with the vorticity of the fluid, providing a window into the plasma’s gyrations.

African penguins have used biological cues in the ocean for centuries to find their favorite fish. Now these cues are trapping juvenile penguins in areas with hardly any food, scientists report February 9 in Current Biology.

It’s the first known ocean “ecological trap,” which occurs when a once-reliable environmental cue instead, often because of human interference, prompts an animal to do something harmful.

When juvenile Spheniscus demersus penguins off the Western Cape of South Africa leave the nest for their maiden voyage at sea, they head for prime penguin hunting grounds. But the fish are no longer there, says Richard Sherley, a marine ecologist with the University of Exeter Environment and Sustainability Institute. Increased ocean temperatures, changes in salinity and overfishing have driven the fish eastward.
Penguins are doing what they’ve evolved to do, following signs in the water to historically prosperous habitats. “But humans have broken the system,” Sherley says, and there’s no longer enough fish to support the seabirds.

Sherley estimates that only about 20 percent of these African penguins survive their first year, partly because they can fall into this ecological trap.
Ecological traps have been documented on land for decades. There has been a lot of speculation about traps in the ocean, but this study is the best evidence so far, says Rob Hale, an ecologist with the University of Melbourne.
“Hopefully the study will generate more interest in examining ecological traps in the ocean so we can better understand when and why traps arise, how they are likely to affect animals, and how we can go about managing their effects,” Hale says.

This trap may have occurred because of how penguins find their food. Researchers think penguins can sense a stress chemical that phytoplankton release when being eaten. Penguins eat sardines, which eat phytoplankton. Usually the chemical, dimethyl sulfide, signals to penguins where the fish are feasting on phytoplankton. But phytoplankton can release the compound in other situations, like in rough water. The signal is still sent, but there are no fish.

“You have a cue that used to signal high quality in an environment, but that environment has been modified by human action to some extent,” Sherley says. “The animals are tricked or trapped into selecting a lower quality habitat because the cue still exists, even though there’s high quality habitat available.”

Adult penguins have adapted to the trap and shifted their hunting patterns to follow the fish east. Sherley says they’re not sure how adults learned to avoid the problem, but that there must be a way that juveniles who survive to adulthood also adapt.

Researchers also tracked juvenile penguins from the Namibia and Eastern Cape of South Africa breeding regions. The eastern penguins have been unaffected by the trap because the fish have moved closer to them. The Namibia population is being barely sustained by the goby, a junk food fish that appears to be taking over the areas previously inhabited by sardines and anchovies.

The Western Cape penguins have been most affected. The population has declined 80 percent in the last 15 years — from 40,000 breeding pairs to 5,000 or 6,000, Sherley says. He estimates that if juvenile penguins hadn’t been falling victim to this trap, the Western Cape population would be double its current levels.

If the loss of fish off the Western Cape of South Africa can’t be reversed, Sherley speculates the two most likely outcomes are an African penguin extinction or an ecosystem shift. Current penguin conservation efforts protect penguin breeding areas, but the study suggests that the protections may be insufficient because the ecological trap is far from the breeding grounds.

Short bouts of suffocating conditions can desolate swaths of seafloor for decades, new research suggests. That devastation could spread in the future, as rising temperatures and agricultural runoff enlarge oxygen-poor dead zones in the world’s oceans.

Monitoring sections of the Black Sea, researchers discovered that even days-long periods of low oxygen drove out animals and altered microbial communities. Those ecosystem changes slow decomposition that normally recycles plant and animal matter back into the ecosystem after organisms die, resulting in more organic matter accumulating in seafloor sediments, the researchers report February 10 in Science Advances.
Carbon is included among that organic matter. Over a long enough period of time, the increased carbon burial could help offset a small fraction of carbon emitted by human activities such as fossil fuel burning, says study coauthor Antje Boetius, a marine biologist at the Max Planck Institute for Marine Microbiology in Bremen, Germany. That silver lining comes at a cost, though. “It means your ecosystem is fully declining,” she says.

“We need to pay more attention to the bottom of the ocean,” says Lisa Levin, a biological oceanographer at the Scripps Institution of Oceanography in La Jolla, Calif. “There’s a lot happening down there.” The new work shows that scientists need to consider oxygen conditions when tracking how carbon moves around the environment, says Levin, who was not involved in the research.
Some oxygen-poor, or hypoxic, waters form naturally, such as the suffocating conditions caused by a lack of churning in the deep realms of the Black Sea (SN Online: 10/9/15). Other regions lose their oxygen to human activities; fertilizer washing in from farms nourishes algal blooms, for example, and the bacteria that later decompose that algal influx suck up oxygen. Rising sea-surface temperatures could worsen these problems by decreasing the amount of dissolved oxygen that water can hold and making it harder for ocean layers to mix, as warmer waters remain on top (SN: 3/5/16, p. 11).
Scientists have noticed increased carbon burial in hypoxic waters before. The mechanism behind that increase was unclear, though. Boetius and colleagues headed out to the Black Sea, the world’s largest oxygen-poor body of water, and studied sites along a 40-kilometer-long stretch of seafloor. (Military activities in the region following Russia’s annexation of Crimea limited where the researchers could study, Boetius says.) Some sites were always flush with oxygen, some occasionally suffered a few days of low oxygen, and others were permanently oxygen-free.

The ecological difference between the sites was stark. In oxygen-rich waters, animals such as fish and starfish flourished, and little organic matter was deposited on the seafloor. In areas with perpetually or sporadically low oxygen, the researchers reported that oxygen-dependent animals were nowhere to be seen, and organic matter burial rates were 50 percent higher.

Bottom-dwelling animals are particularly important, the researchers observed, helping recycle organic matter by eating larger bits of debris sinking from the surface ocean and by mixing oxygen into sediments during scavenging. What’s more, the researchers found that the microbial community in oxygen-poor waters shifted toward those microbes that don’t depend on oxygen to live. Such microbes further limit decomposition by producing sulfur-bearing compounds that make organic matter harder to break down.

Depending on the size of the area affected, animals could take years or decades to return to previously hypoxic waters, Boetius says. Some of the studied sites experienced low-oxygen conditions for only a few days a year yet remained barren even when oxygen returned. The absence of animals prolongs the effects of hypoxic conditions beyond the times when oxygen is scarce, she says.

BOSTON — For the first time since the Viking missions to Mars in the 1970s, NASA is making the search for evidence of life on another world the primary science goal of a space mission. The target world is Jupiter’s moon Europa, considered possibly habitable because of its subsurface ocean.

The proposed mission, which could be operational in the next two decades, calls for a lander with room for roughly 43 kilograms of science instruments. They include a robotic arm to scoop samples and others to analyze the chemistry of the Jovian moon’s icy surface (SN: 5/17/14, p. 20). “It’s the first time in human history that we have the ability to design instruments to detect life within our own solar system’s backyard in the next 20 years,” astrobiologist and planetary scientist Kevin Hand said February 17 at the annual meeting of the American Association for the Advancement of Science. Hand’s team submitted a 264-page report describing the potential mission to NASA on February 8. The report is now open for review by the scientific community.

A major concern is taking precautions to prevent contamination of Europa by microbes from Earth. “These are important for protecting Europa for Europans,” said Hand, who works out of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. His team proposes baking the spacecraft to kill as many microorganisms clinging to the exterior of the lander as possible.

Decontamination precautions are important not only for protecting the life that’s on the world being explored, notes biologist Norine Noonan of the University of South Florida St. Petersburg. They are also important for the science goals of the potential mission. “You don’t want to send a $2 billion spacecraft somewhere to discover E. coli,” Noonan says.

Chimps with little social status influence their comrades’ behavior to a surprising extent, a new study suggests.

In groups of captive chimps, a method for snagging food from a box spread among many individuals who saw a low-ranking female peer demonstrate the technique, say primatologist Stuart Watson of the University of St. Andrews in Fife, Scotland, and colleagues. But in other groups where an alpha male introduced the same box-opening technique, relatively few chimps copied the behavior, the researchers report online February 7 in the American Journal of Primatology.
“I suspect that even wild chimpanzees are motivated to copy obviously rewarding behaviors of low-ranking individuals, but the limited spread of rewarding behaviors demonstrated by alpha males was quite surprising,” Watson says. Previous research has found that chimps in captivity more often copy rewarding behaviors of dominant versus lower-ranking group mates. The researchers don’t understand why in this case the high-ranking individuals weren’t copied as much.

The spread of new behaviors in groups of monkeys and apes depends on a variety of factors — including an innovator’s social status, age and sex — that can interact in unpredictable ways. “That’s why social learning in groups is so interesting to study,” says Elizabeth Lonsdorf, a primatologist at Franklin & Marshall College in Lancaster, Pa., who did not participate in the research.

In the new investigation, perhaps animals were monitoring potential threats from the alpha males more than their box-opening skills. “Alpha male chimps are large, powerful and prone to temper tantrums, so it makes sense to be vigilant for signs of what they’ll do next,” Watson says.

It’s also possible that lower-ranking chimps are sometimes unwilling to copy rewarding behaviors in the presence of a dominant chimp, suggests Lonsdorf. Researchers have reported this form of social deference in capuchin monkeys and rhesus macaques.

Watson’s team studied 38 chimps housed at a research facility in Texas. A low-ranking female from each of two groups and a dominant male from each of two other groups were trained to open a box and remove a piece of fruit. They then performed this feat in front of their home groups during two 20-minute sessions on consecutive days. Trained chimps moved a sliding door on the box up or down until it locked to reveal one of two chambers containing the food. Following each demonstration, group members had eight hours to manipulate the box however they liked.
Individuals who watched low-ranking chimps open the box, but not those who observed dominant chimps do the same, used the demonstrated technique as their first choice more often than expected by chance.

Some, but not all, chimps could have figured out how to open the box on their own, Watson suspects. Of 15 chimps from nonexperimental groups — each given 20 minutes to manipulate the fruit box — five failed to open it.

Unexpectedly, two low-ranking female chimps from different groups discovered a way to game the experimental box after watching dominant males open it. These animals realized that the contraption held two pieces of fruit, one in an upper chamber exposed by sliding the door down until it locked and another in a lower chamber revealed by sliding the door up to lock. Each chimp managed to slide the door up and down just enough, without locking it, to snatch both snacks.

In one group, the alpha male, who had originally demonstrated the locking technique to his group, started copying the low-ranking female’s superior approach. In the other group, two high-ranking females adopted the innovative box-opening method after seeing it performed by their social inferior.

Watson doesn’t know if low-ranking chimps are particularly apt to devise clever behaviors that others copy. It wouldn’t be surprising, he says, since chimps low on the social totem pole typically get less food than others and need to supplement their diets in creative ways.

In wild chimp communities, it’s unclear why certain novel behaviors catch on, Lonsdorf says. For example, young females move to new groups at sexual maturity, so they may bring useful knowledge from one community to another. In one reported case, chimps apparently learned how to use branches and other probes to collect and eat ants after observing the behavior in a recently arrived young female (SN: 2/9/13, p. 20).

Amid a flurry of cabinet appointments and immigration policies, the Trump administration has announced one thing it will not do: pursue policies that protect transgender children in public schools.

The Feb. 22 announcement rescinds Obama administration guidelines that, among other protections, allow transgender kids to use bathrooms and participate in sports that correspond with their genders, and to be called by their preferred names and pronouns.

In a Feb. 23 news briefing, White House press secretary Sean Spicer said that this is a states’ rights issue. “States should enact laws that reflect the values, principles, and will of the people in their particular state,” he said. “That’s it, plain and simple.”

But this “plain and simple” move could be quite dangerous, even deadly, science suggests. Transgender children, who are born one biological sex but identify as the other, already face enormous challenges as they move through a society that often doesn’t understand or accept them. Consider this: Nearly half (46.5 percent) of young transgender adults have attempted suicide at some point in their lives, a recent survey of over 2,000 people found. Nearly half. For comparison, the attempted suicide rate among the general U.S. population is estimated to be about 4.6 percent.

What’s more, a 2015 study in the Journal of Adolescent Health found that transgender youth are two to three times as likely as their peers to suffer from depression and anxiety disorders, or to attempt suicide or harm themselves. These troublesome stats, based on a sample of 180 transgender children and young adults in Boston ages 12 to 29, applied equally to those who underwent male-to-female transitions and those who underwent female-to-male transitions.

The science is clear: Many transgender kids already have to overcome big challenges. To have the federal government proclaim that it won’t stop states from denying equal protection to transgender children makes a difficult situation even worse.

The American Academy of Pediatrics agrees. On February 23, AAP president Fernando Stein issued a statement condemning the new guidelines. “Policies excluding transgender youth from facilities consistent with their gender identity have detrimental effects on their physical and mental health, safety and well-being,” he wrote. “No child deserves to feel this way, especially within the walls of their own school.”

As that statement points out, policies that run counter to a child’s gender identity can cause harm in several ways. One obvious way comes from the physical effects of not having access to bathrooms. In a study of 93 transgender adults, 68 percent reported having been verbally harassed while trying to use a public bathroom, and 18 percent said they had been turned away from a bathroom. To avoid these confrontations, transgender people often resort to not drinking water or simply holding in their urine, measures that can cause dehydration or urinary tract infections, that same survey found.
Those are the experiences of transgender adults who were aware of the health effects of not using the bathroom. Now think about how a young transgender child in school might navigate that situation. A school bathroom can be a scary place for any first grader, let alone one who risks ridicule or worse for walking into the boys’ or girls’ room.

Beyond the physical harms of not having access to a bathroom, restrictive policies also carry heavy psychological harms. Rules that fail to recognize these children’s genders create stigma, and these policies may have harmful consequences on mental health.

The story of same-sex marriage legalization, an issue that’s been around for decades, holds lessons in how policy can influence mental health. Before the U.S. Supreme Court’s 2015 decision to uphold the right of people of the same sex to marry, states had piecemeal policies, creating a natural experiment of sorts. In states that had recently legalized same-sex marriage, fewer teenagers attempted suicide, scientists reported February 20 in JAMA Pediatrics. In the states’ study, the drop was particularly steep for gay, lesbian and bisexual teens, health and social policy researcher Julia Raifman of Johns Hopkins Bloomberg School of Public Health and colleagues found. Although that study can’t determine the cause of the drop, Raifman suspects that the same-sex laws helped reduce negative stigma, and as a result, improved mental health. Mental health benefits have been documented in gay, lesbian and bisexual adults who are in legally recognized relationships. Marriage bans, on the other hand, had a negative effect.

Raifman says that the announcement from the Trump administration “suggests that transgender youth are different, negatively stereotypes transgender youth, gives transgender youth lesser rights, and allows for states or municipalities to use their power to enforce lesser rights.”

Gender is not a choice. Transgender children are quite clear on their gender identity, often from an early age. It’s easy to lose sight of the fact that behind these dreary statistics is someone’s daughter or son, a vulnerable child that the science clearly shows is at a greater risk of suffering simply because of how he or she was born.

From deep in the gold mines of South Africa’s Orange Free State has come evidence that there was some form of biologic activity on Earth at least 2.15 billion years ago. Polymerized hydrocarbon “chemo-fossils” found in the gold ores … [probably] were originally part of a rich bacterial and algal life in the Witwatersrand basin. Since the rock layers from which they come have been dated to about 2.15 billion years ago, it seems likely that photosynthesis existed on Earth before then. — Science News, March 18, 1967

UPDATE
Scientists still debate when early photo­synthesizing organisms called cyanobacteria began pumping oxygen into Earth’s atmosphere. Recent evidence suggests the microbes existed some 3.2 billion years ago (SN Online: 9/8/15), even though a larger oxygen surge didn’t happen until about 2.4 billion years ago (SN: 3/4/17 p. 9). Those tiny bacteria left an outsized impact on our planet, releasing extra oxygen into the atmosphere that paved the way for complex multicellular life like plants and animals.

Catch sight of someone scratching and out of nowhere comes an itch, too. Now, it turns out mice suffer the same strange phenomenon.

Tests with mice that watched itchy neighbors, or even just videos of scratching mice, provide the first clear evidence of contagious scratching spreading mouse-to-mouse, says neuroscientist Zhou-Feng Chen of Washington University School of Medicine in St. Louis. The quirk opens new possibilities for exploring the neuroscience behind the spread of contagious behaviors.
For the ghostly itch, experiments trace scratching to a peptide nicknamed GRP and areas of the mouse brain better known for keeping the beat of circadian rhythms, Chen and colleagues found. They report the results in the March 10 Science.

In discovering this, “there were lots of surprises,” Chen says. One was that mice, nocturnal animals that mostly sniff and whisker-brush their way through the dark, would be sensitive to the sight of another mouse scratching. Yet Chen had his own irresistible itch to test the “crazy idea,” he says.

Researchers housed mice that didn’t scratch any more than normal within sight of mice that flicked and thumped their paws frequently at itchy skin. Videos recorded instances of normal mice looking at an itch-prone mouse mid-scratch and, shortly after, scratching themselves. In comparison, mice with not-very-itchy neighbors looked at those neighbors at about the same frequency but rarely scratched immediately afterward.
Videos of scratching mice produced the same result. More audience itching and scratching followed a film of a mouse with itchy skin than one of a mouse poking about on other rodent business.
Next, researchers looked at how contagious itching plays out in the mouse nervous system. Brains of mice recently struck by contagious urges to scratch showed heightened activity in several spots, including, surprisingly, a pair of nerve cell clusters called the suprachiasmatic nuclei, or SCN. People have these clusters, too, deep in the brain roughly behind the eyes.

Other tests linked the contagious itching with GRP, previously identified as transmitting itch information elsewhere in the mouse nervous system. Mice didn’t succumb to contagious itching if they had no working genes for producing GRP or the molecule that detects it. Yet these mice still scratched when researchers irritated their skin. Also, in normal mice, a dose of GRP injected to the SCN brain regions brought on scratching without the sight of an itchy neighbor, but a dose of plain saline solution to same spots failed to set off much pawing.

It’s fine work, says dermatologist Gil Yosipovitch, who studies itching at the University of Miami. But he wonders how the mouse discovery might apply to people. So far, brain imagery in his own work has not turned up evidence for an SCN role in human contagious itching, he says.

SCN is better known as a circadian timekeeper, responding to cues in light. It’s unclear how the nerve cell clusters might orchestrate behavior based on seeing a scratching mouse, “a very specific and rich visual stimulus,” says psychologist and neuroscientist Henning Holle of the University of Hull in England. Other research suggests different brain regions are involved in contagious itching in people.

Tracking down the mechanisms behind the phenomenon is more than an intriguing science puzzle, Yosipovitch says. People troubled with strong, persistent itching are often unusually susceptible to contagious scratching, and new ideas for easing their misery would be welcome.