Why poison frogs don't poison themselves

The phantasmal poison frog, Epipedobates anthonyi, is the original source of epibatidine, discovered by John Daly in 1974. In fact, epibatidine is named for frogs of this genus. Epibatidine has not been found in any animal outside of Ecuador, and its ultimate source, proposed to be an arthropod, remains unknown. This frog was captured at a banana plantation in the Azuay province in southern Ecuador in August 2017.

Don't let their appearance fool you: Thimble-sized, dappled in cheerful colors and squishy, poison frogs in fact harbor some of the most potent neurotoxins we know. With a new paper published in the journal Science, scientists are a step closer to resolving a related head-scratcher -- how do these frogs keep from poisoning themselves? And the answer has potential consequences for the fight against pain and addiction.

The new research, led by scientists at The University of Texas at Austin, answers this question for a subgroup of poison frogs that use the toxin epibatidine. To keep predators from eating them, the frogs use the toxin, which binds to receptors in an animal's nervous system and can cause hypertension, seizures, and even death. The researchers discovered that a small genetic mutation in the frogs -- a change in just three of the 2,500 amino acids that make up the receptor -- prevents the toxin from acting on the frogs' own receptors, making them resistant to its lethal effects. Not only that, but precisely the same change appeared independently three times in the evolution of these frogs.

"Being toxic can be good for your survival -- it gives you an edge over predators," said Rebecca Tarvin, a postdoctoral researcher at UT Austin and a co-first author on the paper. "So why aren't more animals toxic? Our work is showing that a big constraint is whether organisms can evolve resistance to their own toxins. We found evolution has hit upon this same exact change in three different groups of frogs, and that, to me, is quite beautiful."

There are hundreds of species of poisonous frogs, each of which uses dozens of different neurotoxins. Tarvin is part of a team of researchers, including professors David Cannatella and Harold Zakon in the Department of Integrative Biology, who have been studying how these frogs evolved toxic resistance.

For decades, medical researchers have known that this toxin, epibatidine, also can act as a powerful nonaddictive painkiller. They've developed hundreds of compounds from the frogs' toxin, including one that advanced in the drug-development process to human trials before being ruled out due to other side effects.

The new research -- showing how certain poison frogs evolved to block the toxin while retaining use of receptors the brain needs -- gives scientists information about epibatidine that could eventually prove helpful in designing drugs such as new pain relievers or drugs to fight nicotine addiction.

"Every bit of information we can gather on how these receptors are interacting with the drugs gets us a step closer to designing better drugs," said Cecilia Borghese, another co-first author of the paper and a research associate in the university's Waggoner Center for Alcohol and Addiction Research.

Changing the Lock

A receptor is a type of protein on the outside of cells that transmits signals between the outside and the inside. Receptors are like locks that stay shut until they encounter the correct key. When a molecule with just the right shape comes along, the receptor gets activated and sends a signal.

The receptor that Tarvin and her colleagues studied sends signals in processes like learning and memory, but usually only when a compound that is the healthy "key" comes into contact with it. Unfortunately for the frogs' predators, toxic epibatidine also works, like a powerful skeleton key, on the receptor, hijacking cells and triggering a dangerous burst of activity.

The researchers found that poison frogs that use epibatidine have developed a small genetic mutation that prevents the toxin from binding to their receptors. In a sense, they've blocked the skeleton key. They also have managed, through evolution, to retain a way for the real key to continue to work, thanks to a second genetic mutation. In the frogs, the lock became more selective.

Fighting Disease

The way that the lock changed suggests possible new ways to develop drugs to fight human disease.

The researchers found that the changes that give the frogs resistance to the toxin without changing healthy functioning occur in parts of the receptor that are close to, but don't even touch epibatidine. Borghese and Wiebke Sachs, a visiting student, studied the function of human and frog receptors in the lab of Adron Harris, another author on the paper and associate director of the Waggoner Center.

"The most exciting thing is how these amino acids that are not even in direct contact with the drug can modify the function of the receptor in such a precise way," Borghese said. The healthy compound, she continued, "keeps working as usual, no problem at all, and now the receptor is resistant to epibatidine. That for me was fascinating."

Understanding how those very small changes affect the behavior of the receptor might be exploited by scientists trying to design drugs that act on it. Because the same receptor in humans is also involved in pain and nicotine addiction, this study might suggest ways to develop new medications to block pain or help smokers break the habit.

Retracing Evolution

Working with partners in Ecuador, the researchers collected tissue samples from 28 species of frogs -- including those that use epibatidine, those that use other toxins and those that are not toxic. Tarvin and hear colleagues Juan C. Santos from St. John's University and Lauren O'Connell from Stanford University sequenced the gene that encodes the particular receptor in each species. She then compared subtle differences to build an evolutionary tree representing how the gene evolved.

This represents the second time that Cannatella, Zakon, Tarvin and Santos have played a role in discovering mechanisms that prevent frogs from poisoning themselves. In January 2016, the team identified a set of genetic mutations that they suggested might protect another subgroup of poison frogs from a different neurotoxin, batrachotoxin. Research published this month was built on their finding and conducted by researchers from the State University of New York at Albany, confirming that one of UT Austin's proposed mutations protects that set of poison frogs from the toxin.

Read more at Science Daily

Solving the Easter Island population puzzle

A detailed study of Easter Island's farming potential reveals the population may have reached 17,500 people in its heyday, which could help unravel the mystery of its giant statues.

Easter Island, known as Rapa Nui by its inhabitants, has been surrounded in mystery ever since the Europeans first landed in 1722. Early visitors estimated a population of just 1,500-3,000, which seemed at odds with the nearly nine hundred giant statues dotted around the Island. How did this small community construct, transport and erect these large rock figures?

A new study, published in the open-access journal Frontiers in Ecology and Evolution, hopes to unravel this mystery by giving the best estimate yet of the maximum population size sustained by Easter Island in its heyday.

"Despite its almost complete isolation, the inhabitants of Easter Island created a complicated social structure and these amazing works of art before a dramatic change occurred," says Dr. Cedric Puleston, lead author of this study, based at the Department of Anthropology, University of California, Davis, USA. "We've tried to solve one piece of the puzzle -- to figure out the maximum population size before it fell. It appears the island could have supported 17,500 people at its peak, which represents the upper end of the range of previous estimates."

He adds, "If the population fell from 17,500 to the small number that missionaries counted many years after European contact, it presents a very different picture from the maximum population of 3,000 or less that some have suggested."

Previous archaeological evidence implies the indigenous people numbered far greater than the 1,500-3,000 individuals encountered in the 18th century. The population history of the island remains highly controversial. In addition to internal conflict, the population crash has been attributed to "ecocide," in which the Island's resources were exhausted by its inhabitants, reducing its ability to support human life.

Puleston and his colleagues examined the agricultural potential of the Island before these events occurred, to calculate how many people the Island could sustain.

"The project, funded by the U.S. National Science Foundation, involved a number of really good researchers, including archaeologists, a local expert in Rapa Nui culture, a soil scientist, a biogeochemist, and a population biologist, to get a thorough picture of what the island was like before European contact," he explains.

"We examined detailed maps, took soil samples around the Island, placed weather stations, used population models and estimated sweet potato production. When we had doubts about one of these factors we looked at the range of its potential values to work out different scenarios."

They found 19% of the Island could have been used to grow sweet potatoes, which was the main food crop. By using information on how birth and death rates at various ages depend on food availability, the researchers calculated the population size that level of production could sustain.

"The result is a wide range of possible maximum population sizes, but to get the smallest values you have to assume the worst of everything," says Puleston. "If we compare our agriculture estimates with other Polynesian Islands, a population of 17,500 people on this size of island is entirely reasonable."

Read more at Science Daily

Children Internalize Gender Stereotypes as Early as Age Ten

Girls are vulnerable and boys are stronger. Boys should have the courage to ask a girl out. If a boy gets his nails done, there’s definitely something feminine about him. Girls should prepare to become wives and mothers, and boys should focus on their careers.

In countries across the world, regardless of economic status, gender stereotypes are thriving. For sure, cultural variations exist, but a new global study of adolescents published in the US-based Journal of Adolescent Health suggests stereotypes begin seeping into the mindset of children early — as early as age 10.

Internalizing unequal gender norms has both immediate and long-term consequences on sexual, reproductive, and mental health, including risk of HIV and other sexually transmitted diseases, complications associated with early pregnancy, substance and alcohol abuse, depression, and suicide. These health concerns, according to the study, begin during adolescence and can carry over into adulthood.

“We found children at a very early age — from the most conservative to the most liberal societies — quickly internalize this myth that girls are vulnerable and boys are strong and independent,” Robert Blum of Johns Hopkins University and director of the Global Early Adolescent Study said in a press release accompanying publication of the study.

The research was a collaboration between the Johns Hopkins Bloomberg School of Public Health and the World Health Organization.

Researchers across 15 countries, including the United States, China, Kenya, Belgium, Nigeria, India, South Africa, and Scotland, among others, interviewed over 400 children aged 10 to 14, along with their parents.

Perception of distinct, gendered roles takes root in a child’s mindset between the age of 10 and 14, according to the report. And while the impact of these stereotypes is not surprising, “the fact that they are so common across cultures and economic status and ingrained in children at such a relatively young age, is unexpected,” Kristin Mmari, a professor at Johns Hopkins University and lead researcher on study, told Seeker.

A 12-year-old girl participating in the study from Delhi recalled one of her female classmates being scolded by a teacher for wearing short skirts and playing with boys. “After the school got over, she was sitting alone when a boy went inside the school and raped her as she wearing short skirt,” the girl is quoted as saying in the study.

The report also highlights progress in challenging gender norms.

In Belgium, girls’ participation in sports was celebrated. “Girls are [one] hundred percent [as involved as] boys in football,” a 13-year-old boy is quoted saying. “[Today] there are more girls playing football than boys.”

In China, however, an 11-year-old boy said girls must display certain male traits like strength, fearlessness, and indifference to pain, before successfully participating in the sport.

A message of strength and virility being passed onto boys across cultures is equally threatening to their development, the study suggests. In China, India, Belgium, and the United States, researchers saw that girls are pushing the boundaries of gender norms more than boys. But boys exploring stereotypically female behavior were seen as socially inferior. As a result, they suffer and tend to be more self-harming, said the researchers.

Mmari says stereotypes can be deconstructed and reformed and are amenable to change. “But do I think it will happen quickly? No,” she said.

Read more at Seeker

Porpoise Burial by Medieval Monks Creates Puzzling Grave Mystery

A porpoise from the medieval period was found buried in what appears to be a formal grave on the island of Chapelle dom Hue in the English Channel.

Folklore holds that the little island of Chapelle Dom Hue, in the English Channel west of Guernsey, was the location of a scenic retreat for medieval monks from the Benedictine priory of Lihou, which is a slightly larger island just to the south. Guernsey archaeologist Philip de Jersey and his colleagues are currently excavating the site to determine, in part, what the monks might have left there.

Recently, de Jersey and his team spotted the outline of a feature in the soil that looked like a grave.

“It certainly resembled medieval graves we have excavated in several sites on the island, and it was only a little way off the east-west orientation, as one would usually expect,” de Jersey told Seeker from the site.

A few days later, he and his team started to excavate the feature and uncovered a skull, which he initially thought was the top of a human skull. While dirt was removed, however, the skull grew ever larger in appearance.

As it turns out, the skull and other remains belonged, not to a human, but to a porpoise. The discovery is the world’s only known porpoise burial from the medieval era or earlier.

The archaeologists were astonished.

“It was entirely consistent with a human burial, which is one of the most puzzling aspects,” de Jersey said. “The grave cut has been dug very carefully, with vertical sides and a flat base cut into the underlying bedrock. This has taken some considerable care and effort.”

The buried porpoise as it was first being uncovered.

Like the beginning of a great murder mystery — the porpoise does appear to have been killed — there is a collection of clues and other information, some of which may have nothing to do with the burial.

So far, de Jersey and his team on the island have uncovered the ruins of a building there erected on an east-west alignment, which supports a religious function, according to the researchers.

“It was quite a substantial structure, small in size, but with thick walls,” de Jersey said.

He added that they have also found a lot of old pottery known as Normandy gritty ware, which was imported to the Channel Islands between the late 10th and early-15th centuries. A priory on Lihou was in use from the mid 12th to the early 14th or early-15th century, but the Chapelle Dom Hue pottery suggests that this smaller island was only occupied by the monks for a relatively short time, probably in the later-14th century.

A photo taken from west of the site, with the medieval building at Chapelle Dom Hue visible in the foreground

Evidence for an even earlier occupation of Chapelle Dom Hue was also found, with flint tools going back to the Neolithic Period (15,200 BC–2,000 BC). The porpoise burial, though, is at the medieval level of the site.

The researchers suspect that the animal was butchered before it was put into the ground.

“The bone preservation, apart from the skull, is very poor in our acidic soul, but it appears as though there are various articulated portions in the grave, not in the association one would expect if it was a complete body,” de Jersey explained.

The monks may therefore have viewed the porpoise more as food than as a revered, sentient being.

“One possibility we have considered is that the ‘grave’ is not a grave at all, but a pit carefully cut in which the butchered porpoise was buried in salt, in order to preserve portions of it,” de Jersey said. “There is contemporary literary evidence of porpoises, or parts of porpoise, being around for longer than it would have been fresh, therefore it must have been preserved somehow, whether through drying or salting.”

Researchers excavating at Chapelle Dom Hue, with Guernsey in the distance

Salting of fish and other edible marine life at the time was normally done in barrels, though. The researchers wonder if the large size of the porpoise might have necessitated a different approach for preparing it.

“If that’s true, then obviously it was never recovered, for some reason — or perhaps it just didn’t work as a technique, so they left it in the ground,” de Jersey said.

Medieval cookbooks do include dishes with porpoise as an ingredient. The late-14th century chef’s tome Forme of Cury, for example, contains such a recipe.

Read more at Seeker

Nanoparticles Keep 3D-Printed Alloys From Cracking

The nanoparticle-functionalized powder is fed into a 3D printer, which layers the powder and laser-fuses each layer to construct a 3D object.

Metals have not yet reached their 3D-printing potential. Of the more than 5,500 alloys used in manufacturing today, many cannot undergo the laser-based melting and quick cooling times without cracking or other defects.

Now researchers at HRL Laboratories, in Malibu, California have figured out that adding nanoparticles to the mix could prevent 3D-printed metals from cracking. Bringing metals into the additive manufacturing arena could lead to innovations in industries from aerospace to biomedicine by improving on conventional casting methods. Using 3D printing also allows products to be customized in a short period of time, making them available for sale more quickly.

“What we’re hoping to do is remove one of the constraints,” John Martin, a researcher at HRL Labs, told Seeker. “If you don’t have to worry about whether the material is going to be strong enough once you produce a part, you can focus on the next step, which is opening up the ideas of young engineers, who are thinking about brand new [design] geometries.”

In lab experiments the researchers 3D-printed two different kinds of aluminum alloys that not only didn’t crack, but were as strong as steel and one-third the weight. Martin and his colleagues published their research findings in the journal Nature.

Martin, who has studied metallurgy, knew the problem was at the atomic level. Metals are crystals and their atoms line up in repeating patterns that make up grains. There are sometimes defects at the boundaries where grains meet up and those defects can cause cracks.

There was also the issue of powdered metal. The process of 3D-printing metal requires that the metal begins as a powder, which is laid down in very thin layers, each one heated with a laser in order to melt it. The molten metal must cool quickly before the next layer of powder is added and laser-heated. The intense heating and quick cooling causes metal grains to solidify in odd shapes, which can lead to cracks.

Because the grains of powder are tiny and measured in microns, Martin and his team thought they could introduce nanosized particles to beef up the metal’s strength. They used a computer program to sort through and analyze more than 4,500 different alloy and nanoparticle combinations to see which ones had atomic structures that would fit together best. The idea was that the grains of metal would glom onto the tiny nanoparticles, sort of like a water vapor droplet that nucleates around a particle of dust to create a drop of rain.

They found that a nanoparticle made of hydrogen-stabilized zirconium would work best with two different kinds of aluminum alloys. During the very first lab experiment, they laid down a thin powdery layer of metal microparticles coated with a very fine layer of nanoparticles before running the laser over it. Layer after layer, the printer created the object until it was finished.

When it was completed, the scientists cut the object in half, then polished it. There were no cracks.

“I was surprised that it worked the first time,” said Martin. “We followed physics, so I wasn’t too shocked that it worked, but it’s easy to write something down on a piece of paper. It’s much harder to follow through.”

Read more at Seeker

Neanderthal Boy Found in Spanish Cave Was Human-Like, but With a Larger Brain

Paleoanthropologist Antonio Rosas sits beside the skeleton of a Neanderthal child.

El Sidrón Cave in northwestern Spain preserved the remains of at least 12 Neanderthals for about 49,000 years until their discovery in 2010. Genetic evidence suggests the group — 3 adult males, 3 adult females, 3 adolescent boys, 2 juveniles, and an infant — were all related. What they were doing in the cave before their demise has intrigued archaeologists and historians since the incredible discovery.

New research on the related individuals, however, began with different, yet no less important, questions: How was Neanderthal physiological development different from that of modern humans, and how and why did Neanderthals evolve such big brains?

It has long been reported that the average Neanderthal adult brain had a volume of approximately 1520 cubic centimeters (92 cubic inches), while the average size of a modern human brain is about 1450 cubic centimeters (88 cubic inches).

Bigger brains are not necessarily always better, though, in terms of intellect. Honeybees, for example, are among the most intelligent insects, yet they obviously have very tiny brains.

Nevertheless, “Neanderthals certainly had, in their own way, a sophisticated intellect in evolutionary terms,” Antonio Rosas, a paleoanthropologist at the National Museum of Natural Sciences in Madrid, told Seeker.

Skeleton of a Neanderthal boy recovered from El Sidrón Cave in Asturias, Spain

Rosas and his colleagues conducted the new physical analysis, focusing on just one of the unearthed Neanderthals, a well-preserved boy dubbed El Sidrón J1, whose mix of baby and adult teeth suggests that he died at 7.69 years of age. The findings of the study, published in the journal Science, consist primarily of three determinations.

First, as co-author Luis Ríos of the museum and the Aranzadi Society of Sciences said during a teleconference with media, “there was no noticeable difference in the growth and maturation of this Neanderthal juvenile in comparison with modern human juveniles.”

The observed similarities could help to explain how Neanderthals and anatomically modern humans interbred: Even today, people of European and Asian descent retain Neanderthal DNA. Intriguingly, arctic indigenous peoples and East Asians today possess the biggest brains in the world. They also retain a higher percentage of early hominid — Neanderthal and Denisovan — DNA than most of us.

Their big brains may be a legacy of that heritage. Climate and latitude could be other factors affecting brain growth, along with nutrition.

The second major finding of the study is that the Neanderthal boy’s brain was still likely growing when his life was cut short. While the researchers do not yet know how he and the other Neanderthals died, they can compare other braincases with that of the remains of this young fellow.

The comparison showed that his brain was roughly 87.5 percent of the size of an average adult Neanderthal brain. A modern human of the same age, on average, tends to have 95 percent of the adult brain weight.

“This longer period of growth may have allowed larger brains and larger bodies to grow,” Rosas said. Although Neanderthals had broader bodies than modern humans, he added, their brain to overall body size ratio was still larger than that of our species. It could then be said that they had more brainpower.

Many researchers over the years have wondered why these brainy individuals then went extinct, but because Neanderthal DNA remains in current populations, these hominids were probably just absorbed into what is now known as Homo sapiens.

Researchers working inside El Sidrón Cave in Asturias, Spain

Since Neanderthal childhood development happened rather slowly, this suggests that youths spent a lot of time with parents, older relatives, and other guardians.

“That allowed them to have more time for learning, as compared to other earlier Homo species,” Rosas said. “However, it is difficult to evaluate the biological meaning of the extra learning time as compared to modern humans.”

The third and final finding of the study is that some vertebrae in the boy had not fused when he died. This is another contrast with modern humans, whose same vertebrae tend to fuse around the ages of 4 to 6 years old. The researchers do not think that the difference was due to some pathology in the boy, but rather was probably a development trait of all Neanderthals.

There was “no evidence of disease in the skeleton” of the boy, Rosas said.

Prior research determined that adult male Neanderthals stood about 5 feet 5 inches, which is only 2 inches shorter than the average height for men in many parts of Asia today. As of 10,000 years ago, European males measured about 5 feet 4 inches, reflecting a likely shrinkage before human height globally began to rise again in most regions in more recent years.

Debate continues over what species was the last common ancestor of Neanderthals and modern humans. Rosas said that some people think the last common ancestor “was Homo heidelbergensis; others think it was an earlier species, such as Homo antecessor.” Determining the answer could pinpoint when bigger brains emerged in the human lineage.

Read more at Seeker

Here’s Why the Ears of Barn Owls Are Ageless, Unlike Other Mammals

Florida, Everglades Agricultural Area, Barn Owl in flight

Even if a person has lived a rather dull, quiet life — no concerts, raucous parties, and other noisy activities — the individual’s sense of hearing will deteriorate to a certain extent over time. By age 65, most people will have lost more than 30 decibels in sensitivity at high frequencies due to age-related hearing deterioration known as presbycusis. The amount can be significantly more, depending on lifestyle and genetics, among other factors.

Barn owls, conversely, appear to experience no such age-related hearing loss. Their ears, according to new research published in the journal Proceedings of the Royal Society B, are ageless.

Co-author Christine Köppl of the University of Oldenburg’s animal physiology and behavior group told Seeker “an ageless ear is possible if the regenerative mechanisms can be kept going.”

That is what she and her colleagues observed in their test subjects: seven barn owls named Weiss, Grün, Rot, Lisa, Bart, Ugle, and Sova. The owls were all hatched in captivity and lived in aviaries.

The researchers divided the owls into two groups based on their respective ages. The owls in the young group were less than 2 years old, whereas the old owls were 13–17 years old. The scientists then tested each owl on its ability to hear frequencies of 0.5, 1, 2, 4, 6.3, 10, and 12 kilohertz.

The scientists trained the owls to travel from one perch to another whenever the birds heard a tone, which lasted for just an instant. Upon successful completion of the tasks, the birds received tasty food rewards. To minimize training effects, the birds were tested separately and the sequence of the various frequencies was randomized for each owl.

In addition to comparing the hearing abilities of young versus old owls, the scientists also tracked the auditory sensitivity of Weiss during his impressive lifetime. This owl lived to be 23, well beyond the typical barn owl lifespan, which is just 4 years in the wild.

All of the tests demonstrated that the owls’ hearing sensitivity was not affected by age. The findings are consistent with prior research that found birds, fish, and amphibians have the capacity to regenerate lost “hair” cells in their hearing sensory organ known as the basilar papilla. The hairs are actually long, flexible organelles that help to convert sound vibrations into electrical signals that travel to the brain along the auditory nerve.

“The regeneration mechanisms, and therefore their benefits, are likely present in all bird species,” senior author Ulrike Langemann told Seeker. “The amazing thing is that the majority of small bird species are rather short-lived, and thus will never really benefit from a preservation of auditory sensitivity at old age.”

Barn owls are considered one of natures super predators because of there silent flight and amazing hearing.

Mammals, including humans, have only a limited capacity to regenerate these hair cells when they are lost not only by aging, but also by injury or disease. According to the National Institutes of Health, more than 90 percent of hearing loss occurs when either hair cells or auditory nerve cells are destroyed.

Langemann and colleagues believe that at some point in mammal evolution, the ability to fully regenerate hair cells was lost.

“The current view is that, unfortunately, the genetic switch for the inner ear of mammals is in the off mode,” Köppl explained.

For barn owls, it appears that natural selection highly favored retention of their hair cell regeneration mechanisms. Lead author Bianca Krumm, also from the University of Oldenburg, said barn owls are predominantly nocturnal hunters with fairly large broods for a bird of their size. Most are between 13–15 inches in length. Females cannot leave their nests within the first five days of their chicks hatching because they must keep their otherwise unprotected offspring sufficiently warm.

“Male barn owls may thus face the job of catching about 30 to 40 mice per night for the family, independent of nocturnal lighting conditions,” Krumm said. “Thus ‘hunting by ear only’ must have been the solution. This includes sensitivity as well as amazing sound localization abilities. Indeed, scientists have shown that a tame barn owl will catch a prey item in complete darkness.”

Aside from their ageless ears, barn owls possess superior hearing to that of humans due to the parabolic shape of the facial disc, the concave collection of feathers on the bird’s heart-shaped face that functions like a satellite dish.

“The parabolic effect of the barn owl’s facial disc improves the sensitivity roughly by a factor of 10 in intensity compared to our human auditory sensitivity,” Langemann said, adding that if tiny headphones are placed directly in the ears of barn owls, their hearing is reduced to that of other bird species.

Barn owl ears are entirely covered with feathers, which is thought to protect the ears and to help reduce air drag when the birds are in flight.

Co-author Georg Klump said the researchers are investigating how different pathologies affect aging mammalian inner ears. They are also hoping to learn more about how barn owls locate prey so accurately using their sense of hearing.

“We are biologists and firmly believe that animals can teach us amazing things,” he said. “Different animals may indicate solutions for some of the many problems related to our modern, but aging, society.”

Read more at Seeker

Jellyfish Sleep, and Now Scientists Wonder If Plants and Bacteria Sleep Too

Close-ups of Cassiopea jellyfish.

Jellyfish lack ears, eyes, a nose, a heart, bones, and a brain. In fact, they don’t even have a head. Their states of being, as they float and pulse rhythmically in water, have therefore mostly been unknown.

Despite the fact that jellyfish lack a centralized nervous system, new research provides strong evidence that these soft-bodied marine organisms sleep. The findings, published in the journal Current Biology, have scientists reevaluating what sleep is and what it does.

“Some people probably think that a brain is needed for a sleep behavior to exist, especially those scientists that focus on the sleep states of mammals,” Michael Abrams of Caltech, who co-led the study with his Caltech colleague Ravi Nath, told Seeker.

“Though there are anecdotal observations that suggest some species don’t sleep, I do not know of any animal that has been fully interrogated that has been proven not to sleep,” he added.

Nath and fellow researchers from three Caltech laboratories — headed up respectively by Paul Sternberg, Viviana Gradinaru, and Lea Goentoro — decided in this case to investigate Cassiopea, aka the Upside-Down Jellyfish. This primitive genus essentially spends its entire life sitting upside down on the ocean floor, pulsating every few seconds.

Three criteria must be met in order for an organism to be considered as “sleeping.” First, it must demonstrate a period of reduced activity. To test this in the jellyfish, the researchers used cameras to continuously monitor the marine dwellers in tanks. The footage revealed that jellyfish go through periods of inactivity at night, only pulsing about 39 times per minute, compared to about 58 times per minute during the day.

“During the jellyfish sleep-like state, we see a reduced number of pulses, and we also see an increase in the frequency and length of pause events,” co-lead author Claire Bedbrook told Seeker.
“Pause events are where the jellyfish stop pulsing altogether for 4–20 seconds. These pause events are rarely seen during the day, when the jellyfish are in their more active state.”

The second criteria for sleep is decreased response to otherwise-arousing stimuli. To test this in the jellyfish, the scientists put a jellyfish on a platform higher up in the tank, and pulled the platform out from underneath the animal once it showed signs of quiescence.

Normally, an alert jellyfish would immediately swim to the bottom of the tank, but the jellyfish in the sleep state floated in the water for up to five seconds before “waking up” and re-orienting itself. This would be like a person sleeping, having a cover pulled off, and then gradually waking up and reacting to the change.

The third and final criteria for sleep is that the organism must show an increased sleep drive when it is deprived of this presumably more restful state.

To test this in the Cassiopea individuals, the researchers pulsed water at them every 10 seconds for 20 minutes, effectively “poking” them to keep them awake. The scientists later observed that the squirted jellyfish were more likely to fall into the sleep-like state during the day, when they would normally be active.

All of the new evidence then supports that jellyfish do indeed sleep, or at least exhibit a sleep-like state. Melatonin, a compound known to promote sleep in humans and other animals, did the same to the jellyfish, the scientists discovered.

Clearly sleep is beneficial to animals, including jellyfish. Nath suggested “that sleep is serving as a period of consolidated energy conservation.” Abrams added, “We see that the jellyfish need sleep for them to behave normally, and this indicates an important role for metabolism.”

As for what happens internally to the jellyfish when they sleep, no one is sure at present. It has not been ruled out that jellyfish dream, for example.

“If jellyfish dream, what would they dream about?” Abrams mused. “For us to approach this question, we would need to directly record the neural activity during the day and night. Though it may be impossible to definitively say that they dream, it would be interesting to see if they have sleep phases, perhaps similar to the neural activity oscillations seen during REM.”

Multiple Cassiopea jellyfish. The animals prefer to sit upside down on the floor of the water column.

Based on this and prior studies, it is possible that Earth’s first multicellular organisms exhibited sleep — or something like it — as well as other behavioral states.

Nath mentioned that jellyfish are among the first animals to develop neurons, so it could be that sleep first evolved with the emergence of these specialized cells that transmit nerve impulses.

Alternatively, sleep may be tied to other biological factors, opening up the possibility that plants and bacteria go through sleep-like states too.

“Plants certainly have different states,” Nath said.

Earlier research has even found that plant leaves can move in response to a biological clock. Some researchers refer to these and other circadian plant phenomena, like the closing of flowers, as “sleep movements.”

“Just like plants and other multicellular organisms, bacteria have different states,” Nath noted,  “although I do not know if they sleep, as there is no detailed study showing that bacteria exhibit a sleep state.”

Read more at Seeker

Mass Extinctions on Earth Coincided With Out-of-Whack Carbon Cycles

Fossil skeleton of a Pteradactyl, from the British Museum's collection

Previous mass extinctions in Earth’s history can illuminate how much carbon human civilization can pump into the environment before risking a catastrophic climate change — and that point may be coming up within a century.

That’s the conclusion of Daniel Rothman, a geophysicist at the Massachusetts Institute of Technology, who built a database of fossil records going back half a billion years. Rothman found the periods in which large percentages of existing species died off coincided with big swings in the carbon isotopes found in those records, suggesting the planet’s carbon cycle was out of whack.

“It implies changes in the carbon cycle are likely both an indication of some kind of serious change and possibly a player in amplifying those changes,” Rothman told Seeker.

In a stable environment, carbon ebbs and flows from organic materials. Carbon dioxide fuels photosynthesis in plants, which store it as they grow; when they die and decay, it’s released back into the skies and the oceans.

But human civilization has been pumping more carbon into the environment by burning carbon-rich fossil fuels like coal, oil, and natural gas. On the current trajectory, the oceans are expected to absorb at least another 300 billion tons of carbon by 2100 — an amount that could end up producing long-term changes to the environment, Rothman concluded.

Sedimentary rocks at Meishan, China contain signatures of a disturbance in the carbon cycle immediately preceding Earth's greatest mass extinction.

Passing the threshold Rothman has calculated could mean abrupt environmental change — abrupt in biological and geochemical terms meaning within 10,000 years, Rothman said.

“It’s not that the date 2100 is a magic date,” he said. “It’s that the projection of the amount of carbon that will have been added by anthropogenic means — fossil fuel burning — for the most part suggest that 300 gigaton limit will have been surpassed by end of the century. But it may happen sooner. The question in the end is: What happens next?”

The study was published Wednesday in the research journal Science Advances.

Rothman isn’t alone in warning of a potential extinction. Some scientists argue a sixth such event is under way already, with about two species a year disappearing and thousands seeing their populations and ranges shrink. And scientists have long warned that an increase in global average temperatures beyond 2 degrees Celsius (3.6 degrees Fahrenheit) could have catastrophic consequences.

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Bite force research reveals dinosaur-eating frog

South American horned frog -- Pacman frog -- has tremendous bite force.

Scientists say that a large, now extinct, frog called Beelzebufo that lived about 68 million years ago in Madagascar would have been capable of eating small dinosaurs.

The conclusion comes from a study of the bite force of South American horned frogs from the living genus Ceratophrys, known as Pacman frogs for their characteristic round shape and large mouth, similar to the video game character Pac-Man. Due to their attractive body colouring, voracious appetite, and comically huge heads, horned frogs are very popular in the international pet trade.

Published today in the Nature journal Scientific Reports, the scientists from University of Adelaide, California State Polytechnic University -- Pomona, University of California -- Riverside and UCL, University College London found that living large South American horned frogs have similar bite forces to those of mammalian predators.

"Unlike the vast majority of frogs which have weak jaws and typically consume small prey, horned frogs ambush animals as large as themselves -- including other frogs, snakes, and rodents. And their powerful jaws play a critical role in grabbing and subduing the prey," says Dr Marc Jones, researcher at the University of Adelaide's School of Biological Sciences and honorary researcher at the South Australian Museum.

The study found that small horned frogs, with head width of about 4.5cm, can bite with a force of 30 newtons (N) or about 3 kg or 6.6 lbs. A scaling experiment, comparing bite force with head and body size, calculated that large horned frogs that are found in the tropical and subtropical moist lowland forests of South America, with a head width of up to 10 cm, would have a bite force of almost 500 N. This is comparable to reptiles and mammals with a similar head size.

"This would feel like having 50 litres of water balanced on your fingertip," says Professor Kristopher Lappin, Professor of Biological Sciences at California State Polytechnic University -- Pomona.

Based on their scaling relationship, the scientists estimated the bite force of the giant extinct frog Beelzebufo -- which is in many ways similar to living horned frogs -- may have had a bite up to 2200 N, comparable to formidable mammalian predators such as wolves and female tigers.

"At this bite force, Beelzebufo would have been capable of subduing the small and juvenile dinosaurs that shared its environment," says Dr Jones.

The scientists measured bite force using a custom-made force transducer, a device which accurately measures the force applied to two plates covered with leather when an animal bites them.

"This is the first time bite force has been measured in a frog," says Professor Lappin. "And, speaking from experience, horned frogs have quite an impressive bite, and they tend not to let go. The bite of a large Beelzebufo would have been remarkable, definitely not something I would want to experience firsthand."

Read more at Science Daily

Unique type of object discovered in our solar system

This artist's impression shows the binary asteroid 288P, located in the main asteroid belt between the planets Mars and Jupiter. The object is unique as it is a binary asteroid which also behaves like a comet. The comet-like properties are the result of water sublimation, caused by the heat of the Sun. The orbit of the asteroids is marked by a blue ellipse.

With the help of the NASA/ESA Hubble Space Telescope, a German-led group of astronomers have observed the intriguing characteristics of an unusual type of object in the asteroid belt between Mars and Jupiter: two asteroids orbiting each other and exhibiting comet-like features, including a bright coma and a long tail. This is the first known binary asteroid also classified as a comet. The research is presented in a paper published in the journal Nature today.

In September 2016, just before the asteroid 288P made its closest approach to the Sun, it was close enough to Earth to allow astronomers a detailed look at it using the NASA/ESA Hubble Space Telescope.

The images of 288P, which is located in the asteroid belt between Mars and Jupiter, revealed that it was actually not a single object, but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. That discovery was in itself an important find; because they orbit each other, the masses of the objects in such systems can be measured.

But the observations also revealed ongoing activity in the binary system. "We detected strong indications of the sublimation of water ice due to the increased solar heating -- similar to how the tail of a comet is created," explains Jessica Agarwal (Max Planck Institute for Solar System Research, Germany), the team leader and main author of the research paper. This makes 288P the first known binary asteroid that is also classified as a main-belt comet.

Understanding the origin and evolution of main-belt comets -- comets that orbit amongst the numerous asteroids between Mars and Jupiter -- is a crucial element in our understanding of the formation and evolution of the whole Solar System. Among the questions main-belt comets can help to answer is how water came to Earth. Since only a few objects of this type are known, 288P presents itself as an extremely important system for future studies.

The various features of 288P -- wide separation of the two components, near-equal component size, high eccentricity and comet-like activity -- also make it unique among the few known wide asteroid binaries in the Solar System. The observed activity of 288P also reveals information about its past, notes Agarwal: "Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick."

From this, the team concluded that 288P has existed as a binary system for only about 5000 years. Agarwal elaborates on the formation scenario: "The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the two fragments may have been moved further apart by sublimation torques."

Read more at Science Daily

Social Competition Can Cause Duck Penises to Grow Longer, Faster

A male ruddy duck

Chemical signals released by the individuals around us can have a profound effect on our physical states. For example, many women have noticed a still-mysterious phenomenon coined “menstrual synchrony,” whereby those who have been living or working together in close proximity have their periods at around the same time. 

Now, new research on ducks finds that social environment can even impact penis size. While further research is needed to pinpoint the specific factors that affect penis size in men, the findings — published in The Auk: Ornithological Advances — could lead to future treatments for erectile dysfunction.

As for why scientists are investigating ducks in particular, project leader Patricia Brennan of Mount Holyoke College explained to Seeker that ducks are among the few birds that have a penis.

“I wanted to find out the potential role of sperm competition on shaping the morphology of the penis,” she said. “So I decided to set up experiments to test whether male-male competition could influence male genital morphology.”

Brennan and her colleagues partnered with the cushy Livingstone Ripley Waterfowl Conservancy in Litchfield, Connecticut.

“The ducks were in beautiful, outdoor naturalistic enclosures, and they got used to our manipulation very quickly,” she said, explaining that the “manipulation” meant picking up the male ducks every so often for penis measuring.

A male ruddy duck

The ducks consisted of two species housed separately in either pairs or groups: ruddy ducks, which are very promiscuous, do not form pair bonds, and have relatively long penises and lesser scaups, which form seasonal pair bonds and have relatively short penises.

Over a two-year period, the researchers found that lesser scaup ducks had longer penises, on average, when they were housed in groups with other males. This may also happen to male ducks, like various pekin species, raised for egg, meat, and feather production.

“Anecdotal data suggests that pekin ducks in captivity have longer penises than their wild mallard counterparts, but this may be the result of selection for better breeders in general,” Brennan said.

For the ruddy ducks in the study, the effects were more complicated.

Many ruddy duck males did not reach sexual maturity until the second year of the experiment. When they did reach this life stage, smaller ruddy duck males housed in groups grew their penises faster than males housed in pairs, but they grew out of sync with each other and remained in a reproductive state for only short periods of time.

Collectively, the determinations show that the level of inherent competition that individual male ducks experience just by living together can have a major impact on their genital development.

As for menstrual synchronicity, the probable underlying biochemical factors have to do with hormones. In this case, testosterone and di-hydrotestosterone (DHT) probably underlie the observed duck penis growth differences, outside of factors related to genetics and overall health.

Stress hormones could come into play as well. “In ruddy ducks, the stress from male aggression may be a contributing mechanism for why small males in the groups can’t grow a long penis,” Brennan said.

Before this study, ruddy duck penises had already captured the attention of scientists. These male genitals grow dramatically in the spring — up to about 10 inches long for the ruddy duck, or more than half of a typical male duck’s body length — before shrinking in size just as dramatically in the summer. Additionally, the ruddy duck penis, like that of the pseudo-penis in mallard ducks, is shaped like a corkscrew.

In prior research, Brennan and her team found that this unusual penis shape likely co-evolved with vaginal morphology. Female ruddy ducks have long, corkscrew-shaped vaginas that spiral in the opposite direction of the male’s member. Because insertion is a bit of a challenge, females can ward off some forceful males. The males, in turn, have a better chance of out-competing other would-be suitors, if they manage to penetrate the female first.

Having such a long penis comes with major drawbacks, though.

“I have seen females and other males pecking at the penis immediately after a copulation, and I would imagine this organ is quite vulnerable,” Brennan explained.

She added that male ruddy ducks otherwise keep their penis “inside out, inside a pocket” in the male’s body.

The ancestors of birds all used to have a penis, researchers believe, but most birds evolved other reproductive systems over time, losing their penises in the process. Brennan suspects that dinosaurs had penises, but no one has yet been able to validate this theory, since these are soft tissues that do not fossilize well.

“Part of my research is figuring out the penis loss in birds,” Brennan said. “We don’t have enough evidence to know for sure, but female choice for less aggressive males may have played a role in favoring males with smaller genitalia.”

She would like to perform experiments on female ducks that would parallel those conducted on the ruddy duck and lesser scaup males.

“However,” she said, “to do this study, we would have to sacrifice the females to dissect their vaginas, whereas with the males, we can evert the penis, measure it, and then the males go on happily.”

Read more at Seeker

Scientists Analyze Earth's Elemental Makeup to See How the Planet Was Formed

Exoplanet hunters can determine a remarkable amount of information about distant worlds by studying the planet’s orbital parameters, and also by looking at the planet’s host star. Now scientists from the Australian National University have turned those methods around to provide a closer look at Earth.

In doing so, the team says it has produced the best estimate of Earth’s elemental composition, which has always had a fair amount of uncertainty. The team said that its study also provides more insight into how the Earth formed 4.6 billion years ago.

“Determining the chemical composition of rocky exoplanets was definitely the inspiration for this work,” said Charley Lineweaver, an associate professor at the Australian National University's Planetary Science Institute, in an email to Seeker. “We know the four most abundant elements — iron, oxygen, silicon and magnesium — make up more than 90 per cent of the Earth’s mass, but working out exactly what the Earth is made of has been tricky.”

As the team wrote in its paper, transit photometry and radial velocity measurements can yield rough estimates of the densities and mineralogies of exoplanets. But potentially more precise estimates of the chemical composition of rocky worlds can be made based on the known elemental abundances of their host stars, especially when combined with estimates of how the planets may have initially formed from their stellar nebulae.

“The idea is that rocky planets orbiting their host stars are devolatilized pieces of their host stars,” Lineweaver explained. “Since the processes of devolatilization, sublimation and evaporation are dominated by the universal properties of atoms and molecules, then the effects of these processes could be similar everywhere in the universe.”

So if exoplanet scientists can estimate the chemical composition of unseen rocky planets by applying a devolatilization process, Earth scientists should be able to calibrate that here in our own solar system by comparing the best model of the elemental composition of the Earth with the best model of the elemental composition of the Sun.

The biggest surprise of the research was that no one had actually done this yet.

“‘Surely,’ we said to ourselves initially, ‘Earth scientists will have produced excellent elemental compositions of bulk Earth,’ Lineweaver said in his email. “We found lots of separate papers about the elemental composition of the mantle and we found more speculative papers about the elemental composition of the core. We found lots of heated disagreements between researchers, and we found a woeful neglect of error bars.”

Error bars represent the uncertainty of measurements, providing a general idea of how precise or imprecise a measurement might be. Without quantifying the uncertainties, Lineweaver noted, one can’t combine numbers and know how accurate the numbers are.

This highlights another surprise the researchers found.

“To combine the elemental compositions of the mantle and the core, one crucially needs to know the mass fraction of the core,” Lineweaver continued. “This number tells you how much of the core’s elemental composition you have to add to the mantle’s composition. The core mass fraction has been estimated but no one had gone to the trouble of estimating the uncertainty on that fraction.”

Even though seismological studies of earthquakes provide information about Earth’s core, mantle, and crust, the team said it’s hard to convert this information into an elemental composition. We have also only scratched the surface, so to speak, of our planet. Lineweaver said that rocks on Earth’s surface only come from as deep as the upper mantle, and we’ve only drilled down to 10 kilometers of our 6,400 kilometer radius planet.

Haiyang Wang, a Ph.D. student and the paper’s lead author, said that the team made the most comprehensive estimates of the Earth’s composition based on a “meta-analysis” of previous estimates of the mantle and core, and a new estimate of the core’s mass.

“Our work focused on getting realistic uncertainties so that our reference model can be used in future comparisons of the Earth with the sun, or with Mars or with any other body in the solar system,” said Wang in a statement.

They compiled previous estimates on composition with the most recent data on Earth’s radial density profile to conclude that our planet’s core makes up about 32.5 percent (plus or minus .3 percent) of Earth’s total mass. Iron-nickel alloy accounts for about 87.90 percent of the core with a variety of other elements such as silicone, oxygen, sulfur, and carbon making up the remaining mass.

Read more at Seeker

Synthetic Muscles Could Help Robots Become Stronger and More Dexterous

The artificial muscle in use as a bicep lifts a skeleton's arm to a 90 degree position.

Robots from the real world lack the smooth, lifelike motions of humanoids on TV and in films. Where are the lifelike humanoids from HBO’s Westworld, AMC’s Humans, or the classic Blade Runner?

They may be coming. For the first time, scientists have created an artificial muscle that works in a way similar to natural muscle and could give robots the graceful movements of a human, along with the strength of an industrial machine.

Inspired by human muscle tissue that has the intrinsic capability of expanding and contracting, Aslan Miriyev, a postdoctoral researcher in Columbia University’s Creative Machines Lab, developed a soft, synthetic muscle that can push, pull, bend, and twist in response to heat. In lab experiments, Miriyev and his team showed that the material could expand up to 15 times more than natural muscle and was three times stronger. They also demonstrated that the synthetic muscle was capable of lifting more than 1,000 times its own weight. The findings were published in the journal Nature Communications.

Because the muscle is easy to fabricate and is made from inexpensive, environmentally safe, and biocompatible materials, it could lead to advanced developments in biomedical devices that assist people with physical impairments. I might also advance the development of surgical robots that can grip and manipulate tools or soft tissue, and it could usher in a host of new soft robots able to work safely side-by-side with humans and perform delicate and precise tasks.

“The simplest thing is picking a tomato,” said Miriyev. “If you use a conventional robot, you’ll probably end up with juice.”

Most advanced robots are machines made from rigid materials, like metals and plastics. Soft robots exist, but they’re typically controlled by external air compressors and pumps used to inflate balloon-like structures. Some require voltages that are ten times higher than a household electrical socket to produce a current that simulates movement in stretchy material.

“It’s a little bit scary to use — for example, if you want to put it inside a robot for childcare or elderly care,” said Miriyev.

The material Miriyev and his colleagues developed doesn’t require outside pumps or other external equipment and requires around 10 volts to work.

To make the artificial muscle, the scientists mixed ethanol — a common ingredient used in everything from alcoholic beverages to cleaning products — with liquid silicone rubber. After mixing, microscopic bubbles of ethanol disperse throughout the rubber, and after it cures, the bubbles settle into tiny pockets within the rubber.

By embedding a very thin wire into the matrix of the rubber, the researchers were able to direct a low-voltage current through the material, heating it to 78.4 degrees Celsius (166.6 degrees Fahrenheit), the boiling temperature of ethanol. The boiling increases the volume of the ethanol bubbles — and expands the synthetic muscle.

“We managed to get a straightforward solution for a very tricky, intricate, and challenging [problem],” said Miriyev.

Read more at Seeker

New mirror-coating technology promises dramatic improvements in telescopes

UC Santa Cruz researchers worked with Structured Materials Industries to design and build an atomic layer deposition (ALD) system large enough to accommodate telescope mirrors. Andrew Phillips, Nobuhiko Kobayashi, and David Fryauf (l to r) examine the deposition chamber.

Materials scientist Nobuhiko Kobayashi wasn't quite sure why the astronomer he met at a wine-tasting several years ago was so interested in his research, but as he learned more about telescope mirrors it began to make sense.

"It turns out that improving the performance of mirrors is all about thin-film materials, and that's what I do. So then I got hooked," said Kobayashi, a professor of electrical engineering in the Baskin School of Engineering at UC Santa Cruz.

The astronomer was Joseph Miller, former director of UC Observatories (UCO), whose interest led to a thriving collaboration between Kobayashi and UC Santa Cruz astronomers Andrew Phillips and Michael Bolte. With funding from the National Science Foundation and support from current UCO director Claire Max, the researchers are developing new protective coatings for large silver-based telescope mirrors by adapting a technique widely used in the microelectronics industry.

According to Phillips, most astronomical telescope mirrors use aluminum for the reflective layer, despite the superior reflective properties of silver. "Silver is the most reflective material, but it is finicky to work with, and it tarnishes and corrodes easily," he said. "You need barrier layers on top that can keep anything from getting through to the silver without messing up the optical characteristics of the mirror."

Existing telescopes could substantially increase their efficiency by recoating their mirrors with silver instead of aluminum. "It is by far the cheapest way to make our telescopes effectively bigger," said Bolte. "The reason we want bigger telescopes is to collect more light, so if your mirrors reflect more light it's like making them bigger."

The new coating technology being developed at UC Santa Cruz could make that feasible. The researchers are using a technique called atomic layer deposition (ALD), which gradually builds a thin film of material, one molecular layer at a time, with excellent uniformity, thickness control, and conformity to the surface of the substrate. In a pilot study, ALD provided much better protective coatings for silver mirror samples than traditional physical deposition techniques.

"Atomic layer deposition performs significantly better," Phillips said. "The problem is that the systems used in the electronics industry are designed for silicon wafers, so they're too small for a telescope mirror."

The results of the pilot study, which used an ALD system in Kobayashi's lab designed for microelectronics, convinced the team to design a larger system that could accommodate telescope mirrors. They filed for a patent on their concept and found an equipment vendor willing to work with them to build the system. The vendor, Structured Materials Industries (SMI) in Piscataway, New Jersey, makes thin-film deposition systems for the microelectronics industry.

"We gave them the concept and our requirements, and they did the engineering design work and fabrication," Kobayashi said.

The new system was delivered to his laboratory in July and has performed well in initial testing. The researchers will use the system to demonstrate that it works for telescope mirrors and other large substrates and to continue perfecting the coatings. The system can accommodate a mirror up to 0.9 meter in diameter, and there is no reason the design could not be scaled up to accommodate even larger mirrors or mirror segments, Phillips said. The 10-meter primary mirrors of the twin Keck Telescopes in Hawaii are composed of hexagonal segments 1.8 meters across, and the mirror segments for the Thirty Meter Telescope (TMT) will be 1.4 meters across.

According to Bolte, the desire to use silver on the TMT mirror segments is a major driver of their research on new coating technologies. But he expects the technology will also be used to recoat the mirrors of existing telescopes. An aluminum-coated mirror lasts about three to five years before it needs recoating, a process that puts the telescope temporarily out of action.

"We hate to lose telescope time, and we lose a lot of nights recoating segments at Keck," Phillips said. "We'd like to have a silver coating that could last five to ten years."

At this point, the researchers are using a physical deposition process to put the silver coating on the mirror blanks along with an initial barrier layer to protect the silver while the mirror is transferred to the ALD system. Atomic layer deposition is then used for the final barrier layers.

"Right now, it's a hybrid process, but we're following the development of atomic layer deposition for the silver coating as well," Phillips said.

Read more at Science Daily

Mercury's poles may be icier than scientists thought

Brown University researchers have found new evidence of ice sheets in permanently shadowed craters near the north pole of Mercury. The researcher also suggests that smaller-scale deposits may exist between craters, which would vastly increase the surface ice inventory in Mercury.

The scorching hot surface of Mercury seems like an unlikely place to find ice, but research over the past three decades has suggested that water is frozen on the first rock from the sun, hidden away on crater floors that are permanently shadowed from the sun's blistering rays. Now, a new study led by Brown University researchers suggests that there could be much more ice on Mercury's surface than previously thought.

The study, published in Geophysical Research Letters, adds three new members to the list of craters near Mercury's north pole that appear to harbor large surface ice deposits. But in addition to those large deposits, the research also shows evidence that smaller-scale deposits scattered around Mercury's north pole, both inside craters and in shadowed terrain between craters. Those deposits may be small, but they could add up to a lot more previously unaccounted-for ice.

"The assumption has been that surface ice on Mercury exists predominantly in large craters, but we show evidence for these smaller-scale deposits as well," said Ariel Deutsch, the study's lead author and a Ph.D. candidate at Brown. "Adding these small-scale deposits to the large deposits within craters adds significantly to the surface ice inventory on Mercury."

The idea that Mercury might have frozen water emerged in the 1990s, when Earth-based radar telescopes detected highly reflective regions inside several craters near Mercury's poles. The planet's axis doesn't have much tilt, so its poles get little direct sunlight, and the floors of some craters get no direct sunlight at all. Without an atmosphere to hold in any heat from surrounding surfaces, temperatures in those eternal shadows have been calculated to be low enough for water ice to be stable. That raised the possibility these "radar-bright" regions could be ice.

That idea got a boost after NASA's MESSENGER probe entered Mercury's orbit in 2011. The spacecraft detected neutron signals from the planet's north pole that were consistent with water ice.

For this new study, Deutsch worked with Gregory Neumann from NASA's Goddard Space Flight Center to take a deep dive into the data returned from MESSENGER. They looked specifically at readings from the spacecraft's laser altimeter. The device is mostly used to map elevation, but it can also be used to track surface reflectance.

Neumann, an instrument specialist for the MESSENGER mission, helped to calibrate the altimeter's reflectance signal, which can vary depending upon whether the measurement is taken from directly overhead or at an oblique angle (known as "off-nadir"). That calibration enabled the researchers to detect high reflectance deposits consistent with surface ice in three large craters for which only off-nadir detections were available.

The addition of those craters to Mercury's ice inventory is significant. Deutsch estimates the total area of the three sheets to be about 3,400 square kilometers -- slightly larger than the state of Rhode Island.

But another major aspect of the work is that the researchers also looked at reflectance data for the terrain surrounding those three large craters. That terrain isn't as bright as the ice sheets inside the craters, but it's significantly brighter than the average Mercury surface.

"We suggest that this enhanced reflectance signature is driven by small-scale patches of ice that are spread throughout this terrain," Deutsch said. "Most of these patches are too small to resolve individually with the altimeter instrument, but collectively they contribute to the overall enhanced reflectance."

To seek further evidence that such smaller-scale deposits exist, the researchers looked though the altimeter data in search of patches that were smaller than the big crater-based deposits, but still large enough to resolve with the altimeter. They found four, each with diameters of less than about 5 kilometers.

"These four were just the ones we could resolve with the MESSENGER instruments," Deutsch said. "We think there are probably many, many more of these, ranging in sizes from a kilometer down to a few centimeters."

Knowing that these small-scale deposits exist, and that they're likely the source of the slightly brighter surface outside craters, could dramatically increase the ice inventory on Mercury. Similar small-scale ice deposits are thought to exist on the poles of the Moon. Research models have suggested that accounting for these small-scale deposits roughly doubles the amount of lunar real estate that could harbor ice. The same could be true on Mercury, the researchers say.

How this polar ice may have found its way to Mercury in the first place remains an open question, Deutsch says. The leading hypothesis is that it was delivered by water-rich comet or asteroid impacts. Another idea is that hydrogen may have been implanted in the surface by solar wind, later combining with an oxygen source to form water.

Jim Head, Deutsch's Ph.D. advisor and co-author of the research, said the work adds a new perspective on a critical question in planetary science.

Read more at Science Dialy

US Teens Are Growing Up More Slowly Than They Used To

A group of teenage boys.

Jean Twenge has been researching generational differences for 25 years. Of late, she started to notice that today’s teens aren’t dating and holding down jobs as much as they used to in past decades.

She’s not alone in making such observations, which have sparked spirited online debates about their implications.

“I’d seen trend pieces characterizing these trends as meaning teens were more ‘virtuous,’ when talking about declines in sex or alcohol, or that teens were ‘lazy’ when talking about declines in working,” Twenge, a professor of psychology at San Diego State University, told Seeker. “But I thought both of those missed the big picture — that teens were taking longer to grow up.”

She and her colleague Heejung Park, an assistant professor of psychology at Bryn Mawr College, decided to investigate the matter further.

They analyzed seven surveys, conducted between 1976 and 2016, of 8.3 million 13- to 19-year-olds. The surveys were nationally representative, reflecting the population of US teens in terms of gender, race/ethnicity, socioeconomic status, and geographic region.

In the surveys, teens were asked how they used their time, including their engagement in one or more activities that were considered to be adult in nature. These included dating, working for pay, going out without their parents, driving, and having sex. The massive amount of data allowed Twenge and Park to compare teens in the 2010s to teens in the 2000s, 1990s, 1980s, and 1970s.

The study, published in the journal Child Development, found that adolescents in the present decade are less likely to engage in such adult behaviors, which are mostly tied to independence from parental figures. The trend appeared across all demographic groups, and supports Twenge’s speculation that teens are growing up more slowly than their counterparts from previous decades did.

“I would not describe youths as ‘more immature,’” she said. “That doesn’t fit the larger pattern of the data. Is it more or less mature to have sex or drink alcohol in high school? It’s neither.”

Delayed development throughout the animal kingdom is usually associated with greater time for education, with humans gaining much of this in school. Less schooling does not necessarily mean less learning overall, however.

“For example, when young people on average had less educational opportunities and started working at a job or started their family at earlier ages, they were engaging in different types of learning,” Park explained. “As another example, in cultures and communities where formal schooling is less available, much learning takes place in the home setting through observations and interactions, rather than through explicit forms of teaching and communication.”

Twenge, who is the author of the book iGen: Why Today’s Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy — and Completely Unprepared for Adulthood, noted that more people go to college now than they did in past years.

“Whether they are actually learning more is a question we can’t answer with this data,” she noted.

Three teenage girls taking a selfie.

The researchers determined that the trend toward teens engaging in fewer adult behaviors cannot be explained by the time youths generally spent on homework or extracurricular activities. Twenge and Park said that this is because time doing those activities decreased among eighth and tenth graders, but was steady among twelfth graders and college students.

The decline in adult activities among teens may be linked to the time they spend online, however, since this increased markedly over the span of the surveys.

Electronic devices such as computers and smartphones “likely accelerated some of the trends in the last 10 years, as many of them involve getting out of the house, which is now less necessary for communicating with friends,” explained Twenge.

Human physical development is on a different, genetics-driven timetable than these more culturally-driven changes. Other studies even show that some youths are going through puberty earlier now than they did in past decades. This can put the bodies of adolescents and teens in conflict with societal norms.

For example, while teens may be physically able to have children of their own, others may believe that such younger individuals are not emotionally and/or financially stable enough to have offspring. These same reasons, plus health concerns, have led to the passage of laws governing other adult-associated behaviors, such as driving.

“Due to the slow life strategy,” Twenge said, “adults believe teens should grow up more slowly, and then laws are passed to restrict their access to alcohol, cigarettes, etc.”

For the study, she and Park also examined how changes in family size, life expectancy, education, and the economy may have influenced the rate at which teens engage in adult activities.

These activities were less common during time periods when families had fewer children and higher median income, and when fewer people died of communicable diseases. Longer lives on average, women giving birth at later ages, and completion of education later in life were additional factors associated with teens growing up more slowly.

“Life history theory explicitly notes that slow or fast strategies are not inherently good or bad,” Twenge noted. “They are adaptations to the cultural context.”

“Young people today are exposed to different types of learning than prior generations, due to cultural changes and humans’ tendency to adapt to the changing environmental conditions,” Park added. “Each cultural environment has strengths and weaknesses, so it is important to recognize both what’s being gained and lost as our cultures change.”

Read more at Seeker

‘Astronauts' Simulating Mars Surface Mission Emerge After 8 Months of Isolation

HI-SEAS V crewmembers Brian Ramos and Laura Lark walk around the mock Mars habitat.

After spending eight months simulating life on Mars on the slopes of the Mauna Loa volcano, six "astronauts" emerged from their Hawaiian habitat on Sunday (Sept. 17) to return to civilization.

This concluded the fifth mock Mars mission of the NASA-funded HI-SEAS program (Hawaii Space Exploration Analog and Simulation). Operated by the University of Hawaii, this research project studies how groups of interplanetary travelers would work together on long-term missions while in cramped quarters.

During the mission, four men and two women lived in isolation from the rest of planet Earth and could eat only shelf-stable foods and occasional lab-grown vegetables. When communicating with the outside world, they had to deal with the 20-minute delay that astronauts on Mars would experience as well. And any time they went outside, they had to put on their spacesuits.

The Mission V crew entered the HI-SEAS dome on Jan. 19. During their eight-month stay on Mauna Loa, the world's largest active volcano, they conducted scientific experiments, performed daily exercises and maintained equipment in and around the dome. Outside the dome, the astronauts did geological fieldwork in their spacesuits just as if they were on Mars.

While HI-SEAS studies the more technical and practical aspects of living on Mars, a large part of the investigation is to see how a group of people live together in isolation with little to no privacy.

"Long-term space travel is absolutely possible," Laura Lark, IT specialist for HI-SEAS V, said in a video. "There are certainly technical challenges to be overcome. There are certainly human factors to be figured out, that’s part of what HI-SEAS is for. But I think that overcoming those challenges is just a matter of effort. We are absolutely capable of it."

After the crew emerged from the HI-SEAS dome at 9 a.m. EDT (1300 GMT), they " felt the sun and wind on their faces and ate fresh tropical papaya, pineapple and bananas with friends and family," University of Hawaii officials said in a statement.

"My advice to mission six is say, 'Yes.’" HI-SEAS V health and performance officer Brian Ramos said in the video. "If you have an opportunity whether it’s filming or learning a new science skill or flying the drone, going out to a lava tube, whatever it is, say, "Yes.' Take leadership on things. Honestly, you can come out of here in eight months learning a ton of stuff."

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