Astronomers may have discovered first planet to orbit 3 stars

In a distant star system -- a mere 1,300 light years away from Earth -- UNLV researchers and colleagues may have identified the first known planet to orbit three stars.

Unlike our solar system, which consists of a solitary star, it is believed that half of all star systems, like GW Ori where astronomers observed the novel phenomenon, consist of two or more stars that are gravitationally bound to each other.

But no planet orbiting three stars -- a circumptriple orbit -- has ever been discovered. Perhaps until now.

Takeaways

Using observations from the powerful Atacama Large Millimeter/submillimeter Array (ALMA) telescope, UNLV astronomers analyzed the three observed dust rings around the three stars, which are critical to forming planets.

But they found a substantial, yet puzzling, gap in the circumtriple disc.

The research team investigated different origins, including the possibility that the gap was created by gravitational torque from the three stars. But after constructing a comprehensive model of GW Ori, they found that the more likely, and fascinating, explanation for the space in the disc is the presence of one or more massive planets, Jupiter-like in nature. Gas giants, according to Jeremy Smallwood, lead author and a recent Ph.D. graduate in astronomy from UNLV, are usually the first planets to form within a star system. Terrestrial planets like Earth and Mars follow.

The planet itself cannot be seen, but the finding -- highlighted in a September study in the Monthly Notices of the Royal Astronomical Society -- suggests that this is the first circumtriple planet ever discovered. Further observations from the ALMA telescope are expected in the coming months, which could provide direct evidence of the phenomenon.

"It's really exciting because it makes the theory of planet formation really robust," Smallwood said. "It could mean that planet formation is much more active than we thought, which is pretty cool."

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Scientists discover 14 genes that cause obesity

Promising news in the effort to develop drugs to treat obesity: University of Virginia scientists have identified 14 genes that can cause and three that can prevent weight gain. The findings pave the way for treatments to combat a health problem that affects more than 40% of American adults.

"We know of hundreds of gene variants that are more likely to show up in individuals suffering obesity and other diseases. But 'more likely to show up' does not mean causing the disease. This uncertainty is a major barrier to exploit the power of population genomics to identify targets to treat or cure obesity. To overcome this barrier, we developed an automated pipeline to simultaneously test hundreds of genes for a causal role in obesity. Our first round of experiments uncovered more than a dozen genes that cause and three genes that prevent obesity," said Eyleen O'Rourke of UVA's College of Arts & Sciences, the School of Medicine's Department of Cell Biology and the Robert M. Berne Cardiovascular Research Center. "We anticipate that our approach and the new genes we uncovered will accelerate the development of treatments to reduce the burden of obesity."

OBESITY AND OUR GENES

O'Rourke's new research helps shed light on the complex intersections of obesity, diet and our DNA. Obesity has become an epidemic, driven in large part by high-calorie diets laden with sugar and high-fructose corn syrup. Increasingly sedentary lifestyles play a big part as well. But our genes play an important role too, regulating fat storage and affecting how well our bodies burn food as fuel. So if we can identify the genes that convert excessive food into fat, we could seek to inactivate them with drugs and uncouple excessive eating from obesity.

Genomicists have identified hundreds of genes associated with obesity -- meaning the genes are more or less prevalent in people who are obese than in people with healthy weight. The challenge is determining which genes play causal roles by directly promoting or helping prevent weight gain. To sort wheat from chaff, O'Rourke and her team turned to humble worms known as C. elegans. These tiny worms like to live in rotting vegetation and enjoy feasting on microbes. However, they share more than 70% of our genes, and, like people, they become obese if they are fed excessive amounts of sugar.

The worms have produced great benefits for science. They've been used to decipher how common drugs, including the antidepressant Prozac and the glucose-stabilizing metformin, work. Even more impressively, in the last 20 years three Nobel prizes were awarded for the discovery of cellular processes first observed in worms but then found to be critical to diseases such as cancer and neurodegeneration. They've also been fundamental to the development of therapeutics based on RNA technology.

In new work just published in the scientific journal PLOS Genetics, O'Rourke and her collaborators used the worms to screen 293 genes associated with obesity in people, with the goal of defining which of the genes were actually causing or preventing obesity. They did this by developing a worm model of obesity, feeding some a regular diet and some a high-fructose diet.

This obesity model, coupled to automation and supervised machine learning-assisted testing, allowed them to identify 14 genes that cause obesity and three that help prevent it. Enticingly, they found that blocking the action of the three genes that prevented the worms from becoming obese also led to them living longer and having better neuro-locomotory function. Those are exactly the type of benefits drug developers would hope to obtain from anti-obesity medicines.

More work needs to be done, of course. But the researchers say the indicators are encouraging. For example, blocking the effect of one of the genes in lab mice prevented weight gain, improved insulin sensitivity and lowered blood sugar levels. These results (plus the fact that the genes under study were chosen because they were associated with obesity in humans) bode well that the results will hold true in people as well, the researchers say.

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‘Planet confusion’ could slow Earth-like exoplanet exploration

When it comes to directly imaging Earth-like exoplanets orbiting faraway stars, seeing isn't always believing. A new Cornell University study finds that next-generation telescopes used to see exoplanets could confuse Earth-like planets with other types of planets in the same solar system.

With today's telescopes, dim distant planets are hard to see against the glare of their host stars, but next-generation tools such as the Nancy Grace Roman Space Telescope, currently under development by NASA, will be better at imaging Earth-like planets, which orbit stars at just the right distance to offer prime conditions for life.

"Once we have the capability of imaging Earth-like planets, we're actually going to have to worry about confusing them with completely different types of planets," said Dmitry Savransky, associate professor of mechanical and aerospace engineering and of astronomy.

"The future telescopes that will enable these observations will be so huge, expensive, and difficult to build and launch that we can't afford to waste a single second of time on them," Savransky said, "which is why it is so important to think through all of these potential issues ahead of time."

By using Earth's own solar system as a model of an unexplored star system, Savransky and doctoral student Dean Keithly, calculated that even with direct-imaging techniques and the increased capabilities of future, high-powered telescopes, exoplanets as different as Uranus and Earth could be mistaken for one another.

The research details how measurements estimating planet-star separation and brightness can cause "planet confusion." The modeling finds that when two planets share the same separation and magnitude along their orbits, one planet can be confused for the other.

Keithly and Savransky identified 21 cases within their solar system model in which an individual planet had the same apparent planet-star separation and brightness as another planet. Using this data, it was calculated that an Earth-like planet could be misidentified with a Mercury-like planet in 36% of randomly generated solar systems; with a Mars-like planet in about 43% of randomly generated solar systems; and with a Venus-like planet in more than 72% of randomly generated solar systems.

In contrast, confusion between Earth-like planets and larger gas-giant planets similar to Neptune, Saturn and Uranus was less likely, and could occur in 1-4% of randomly generated solar systems.

Confusing planets for one another can be an expensive and time-consuming problem for scientists. Extensive planning and funds go into each use of a high-powered telescope, so the false identification of a habitable exoplanet wastes valuable telescope time. With this problem identified, researchers can design more efficient exoplanet direct-imaging mission surveys.

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Toothy grins from the past: Ancient birds replaced their teeth like living crocodilians

The birds flapping around in the Age of Dinosaurs had all sorts of different teeth in their mouths. Toothed birds went extinct along with their giant cousins, and modern dinosaurs-birds-are famously toothless.

Paleontologists have known that toothed birds lived in the Mesozoic since the discovery of the iconic Archaeopteryx in the 19th century. They also discovered that these birds replaced their teeth similar to some reptiles, but detailed examination of the tooth replacement process was limited.

In a new paper published in Scientific Reports, Graduate Student In-Residence at the Natural History Museum of Los Angeles County's Dinosaur Institute, Becky Wu, along with an international team of researchers from NHMLAC, used µCT imaging to get the first detailed look at the tooth replacement pattern of three newly discovered extinct Cretaceous birds from Brazil.

Wu and her colleagues suspected that to better understand the tooth replacement process and patterns, they would have to look inside the jaw. While previous studies have explored tooth replacement in ancient birds, they were limited primarily to what they could see on the outside. Wu and her colleagues applied microcomputed tomography to the fossils at the Molecular Imaging Center at the University of Southern California. Just like CT scans in hospitals or at dentists, this technology helped visualize the new forming bird teeth in the exquisitely preserved jawbones, helping Wu and her colleagues get closer to the root of tooth replacement patterns in these ancient birds.

"We kind of guessed," Wu said. "We thought they probably had the replacement teeth, and were very happy to find them. This is the first time we were able to reconstruct the tooth replacement in a tooth row of birds, including those teeth that are still in their early stages."

"The great preservation of the fossil and the high-resolution CT scan made this possible," Wu continued, "We have records of tooth replacement in different developmental stages; this new data gives us a sneak peek of their tooth cycle. And since the specimens had preserved consecutive neighboring functional and replacement teeth, we can now visualize their tooth replacement pattern."

"We need three-dimentional data technologies like the synchrotron and CT scanning to understand the evolution and pattern of dental replacement and the mechanism of this complicated regeneration process," says Wu.

The researchers discovered an alternating pattern of tooth replacement, similar to the pattern found in other dinosaurs and crocodilians. Even though the ancestors of crocodilians and dinosaurs split millions of years before either group appeared, crocodilians are currently the only living close-toothed relative to birds. The study's findings imply that the genetic controls for tooth replacement survived that split.

"Crocodilians and birds stand on two ends of a diverse, connected family tree, yet the similarity of their tooth replacements suggests that the genetic mechanisms behind this process may have a deeper origin in that tree. We still need more data to fill our knowledge gaps, including data on crocodilians and dinosaurs' ancestors and relatives and data on lineages closer to birds."

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Morality demonstrated in stories can alter judgement for early adolescents

An important lesson in the moral education of children could be as close as the book in their hands. Stories matter. And they can play a role in shifting the importance of particular moral values in young audiences, according to the results of a new study.

"Media can distinctly influence separate moral values and get kids to place more or less importance on those values depending on what is uniquely emphasized in that content," says Lindsay Hahn, PhD, an assistant professor of communication in the University at Buffalo College of Arts and Sciences.

Hahn is first author of the new study, which adds critical nuance to a body of literature that explores how media content affects children. While many previous studies have focused on broad conceptualizations, like prosocial or antisocial effects that might be associated with specific content, Hahn's study looks at how exposure to content featuring specific moral values (care, fairness, loyalty and authority) might influence the weight kids place on those values.

Do children reading about particular moral characteristics absorb those traits as a building block for their own morality? The findings, which appear in the Journal of Media Psychology, suggest so, and further support how this indirect approach to socializing children's morality can supplement the direct teaching of moral principles kids might receive through formal instruction.

"Parents, caregivers and teachers are often wondering how media can be used for good," says Hahn, an expert in media psychology and media effects. "How can it be used for good things? How can it discourage bad habits? How can it educate?"

Answering those questions begins with a better understanding about how to use media.

"When parents are considering what media they might want to select for their children, they can take into account what particular moral value is being emphasized by the main character, and how the main character is treated because of those actions," she says.

For the study, Hahn and her colleagues took the main character from a young adult novel and edited the content to reflect in each version the study's focus on one of four moral values. A fifth version was manipulated in a way that featured an amoral main character. Those narratives were shared with roughly 200 participants between the ages of 10 and 14. This is a favorable range for media research because it's more difficult to introduce narrative comprehension in younger kids, while equally challenging to hold the attention of older adolescents, who become bored with rudimentary storylines, according to Hahn.

The team then created a scale designed to measure the importance kids place on moral values to determine how participants might be influenced by specific narratives.

"Measuring these effects can be difficult," says Hahn. "That's why, in addition to testing our hypothesis, another purpose of this research was to develop a measure of moral values for kids. Nothing like that exists yet, that we know of."

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Age and aging have critical effects on the gut microbiome

Researchers at Cedars-Sinai have found that aging produces significant changes in the microbiome of the human small intestine distinct from those caused by medications or illness burden. The findings have been published in the journal Cell Reports.

"By teasing out the microbial changes that occur in the small bowel with age, medication use and diseases, we hope to identify unique components of the microbial community to target for therapeutics and interventions that could promote healthy aging," said Ruchi Mathur, MD, the study's principal investigator.

Research exploring the gut microbiome, and its impact on health, has relied predominantly on fecal samples, which do not represent the entire gut, according to Mathur. In their study, investigators from Cedars-Sinai's Medically Associated Science and Technology (MAST) Program analyzed samples from the small intestine-which is over 20 feet in length and has the surface area of a tennis court-for examination of the microbiome and its relationship with aging.

"This study is the first of its kind to examine the microbial composition of the small intestine of subjects 18 years of age to 80. We now know that certain microbial populations are influenced more by medications, while others are more affected by certain diseases. We have identified specific microbes that appear to be only influenced by the chronological age of the person," said Mathur, an endocrinologist and director of the Diabetes Outpatient Treatment & Education Center.

The 21st century has been referred to as the "era of the gut microbiome" as scientists turn considerable attention to the role trillions of gut bacteria, fungi and viruses may play in human health and disease. The microbiome is the name given to the genes that live in these cells. Studies have suggested that disturbances in the constellations of the microbial universe may lead to critical illnesses, including gastroenterological diseases, diabetes, obesity, and some neurological disorders.

While researchers know that microbial diversity in stool decreases with age, Cedars-Sinai investigators identified bacteria in the small bowel they refer to as "disruptors" that increase and could be troublesome.

"Coliforms are normal residents of the intestine. We found that when these rod-shaped microbes become too abundant in the small bowel-as they do as we get older-they exert a negative influence on the rest of the microbial population. They are like weeds in a garden," said study co-author Gabriela Leite, PhD.

Investigators also found that as people age, the bacteria in the small intestine change from microbes that prefer oxygen to those that can survive with less oxygen, something they hope to understand as the research continues.

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Investigating the potential for life around the galaxy’s smallest stars

When the world's most powerful telescope launches into space this year, scientists will learn whether Earth-sized planets in our 'solar neighborhood' have a key prerequisite for life -- an atmosphere.

These planets orbit an M-dwarf, the smallest and most common type of star in the galaxy. Scientists do not currently know how common it is for Earth-like planets around this type of star to have characteristics that would make them habitable.

"As a starting place, it is important to know whether small, rocky planets orbiting M-dwarfs have atmospheres," said Daria Pidhorodetska, a doctoral student in UC Riverside's Department of Earth and Planetary Sciences. "If so, it opens up our search for life outside our solar system."

To help fill this gap in understanding, Pidhorodetska and her team studied whether the soon-to-launch James Webb Space Telescope, or the currently-in-orbit Hubble Space Telescope, are capable of detecting atmospheres on these planets. They also modeled the types of atmospheres likely to be found, if they exist, and how they could be distinguished from each other. The study has now been published in the Astronomical Journal.

Study co-authors include astrobiologists Edward Schwieterman and Stephen Kane from UCR, as well as scientists from Johns Hopkins University, NASA's Goddard Space Flight Center, Cornell University and the University of Chicago.

The star at the center of the study is an M-dwarf called L 98-59, which measures only 8% of our sun's mass. Though small, it is only 35 light years from Earth. It's brightness and relative closeness make it an ideal target for observation.

Shortly after they form, M-dwarfs go through a phase in which they can shine two orders of magnitude brighter than normal. Strong ultraviolet radiation during this phase has the potential to dry out their orbiting planets, evaporating any water from the surface and destroying many gases in the atmosphere.

"We wanted to know if the ablation was complete in the case of the two rocky planets, or if those terrestrial worlds were able to replenish their atmospheres," Pidhorodetska said.

The researchers modeled four different atmospheric scenarios: one in which the L 98-59 worlds are dominated by water, one in which the atmosphere is mainly composed of hydrogen, a Venus-like carbon dioxide atmosphere, and one in which the hydrogen in the atmosphere escaped into space, leaving behind only oxygen and ozone.

They found that the two telescopes could offer complementary information using transit observations, which measure a dip in light that occurs as a planet passes in front of its star. The L 98-59 planets are much closer to their star than Earth is to the sun. They complete their orbits in less than a week, making transit observations by telescope faster and more cost effective than observing other systems in which the planets are farther from their stars.

"It would only take a few transits with Hubble to detect or rule out a hydrogen- or steam-dominated atmosphere without clouds," Schwieterman said. "With as few as 20 transits, Webb would allow us to characterize gases in heavy carbon dioxide or oxygen-dominated atmospheres."

Of the four atmospheric scenarios the researchers considered, Pidhorodetska said the dried-out oxygen-dominated atmosphere is the most likely.

"The amount of radiation these planets are getting at that distance from the star is intense," she said.

Though they may not have atmospheres that lend themselves to life today, these planets can offer an important glimpse into what might happen to Earth under different conditions, and what might be possible on Earth-like worlds elsewhere in the galaxy.

The L 98-59 system was only discovered in 2019, and Pidhorodetska said she is excited to get more information about it when Webb is launched later this year.

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Zeroing in on the origins of Earth’s 'single most important evolutionary innovation'

Some time in Earth's early history, the planet took a turn toward habitability when a group of enterprising microbes known as cyanobacteria evolved oxygenic photosynthesis -- the ability to turn light and water into energy, releasing oxygen in the process.

This evolutionary moment made it possible for oxygen to eventually accumulate in the atmosphere and oceans, setting off a domino effect of diversification and shaping the uniquely habitable planet we know today.

Now, MIT scientists have a precise estimate for when cyanobacteria, and oxygenic photosynthesis, first originated. Their results appear in the Proceedings of the Royal Society B.

They developed a new gene-analyzing technique that shows that all the species of cyanobacteria living today can be traced back to a common ancestor that evolved around 2.9 billion years ago. They also found that the ancestors of cyanobacteria branched off from other bacteria around 3.4 billion years ago, with oxygenic photosynthesis likely evolving during the intervening half-billion years, during the Archean Eon.

Interestingly, this estimate places the appearance of oxygenic photosynthesis at least 400 million years before the Great Oxidation Event, a period in which the Earth's atmosphere and oceans first experienced a rise in oxygen. This suggests that cyanobacteria may have evolved the ability to produce oxygen early on, but that it took a while for this oxygen to really take hold in the environment.

"In evolution, things always start small," says lead author Greg Fournier, associate professor of geobiology in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Even though there's evidence for early oxygenic photosynthesis -- which is the single most important and really amazing evolutionary innovation on Earth -- it still took hundreds of millions of years for it to take off."

Fournier's MIT co-authors include Kelsey Moore, Luiz Thiberio Rangel, Jack Payette, Lily Momper, and Tanja Bosak.

Slow fuse, or wildfire?

Estimates for the origin of oxygenic photosynthesis vary widely, along with the methods to trace its evolution.

For instance, scientists can use geochemical tools to look for traces of oxidized elements in ancient rocks. These methods have found hints that oxygen was present as early as 3.5 billion years ago -- a sign that oxygenic photosynthesis may have been the source, although other sources are also possible.

Researchers have also used molecular clock dating, which uses the genetic sequences of microbes today to trace back changes in genes through evolutionary history. Based on these sequences, researchers then use models to estimate the rate at which genetic changes occur, to trace when groups of organisms first evolved. But molecular clock dating is limited by the quality of ancient fossils, and the chosen rate model, which can produce different age estimates, depending on the rate that is assumed.

Fournier says different age estimates can imply conflicting evolutionary narratives. For instance, some analyses suggest oxygenic photosynthesis evolved very early on and progressed "like a slow fuse," while others indicate it appeared much later and then "took off like wildfire" to trigger the Great Oxidation Event and the accumulation of oxygen in the biosphere.

"In order for us to understand the history of habitability on Earth, it's important for us to distinguish between these hypotheses," he says.

Horizontal genes

To precisely date the origin of cyanobacteria and oxygenic photosynthesis, Fournier and his colleagues paired molecular clock dating with horizontal gene transfer -- an independent method that doesn't rely entirely on fossils or rate assumptions.

Normally, an organism inherits a gene "vertically," when it is passed down from the organism's parent. In rare instances, a gene can also jump from one species to another, distantly related species. For instance, one cell may eat another, and in the process incorporate some new genes into its genome.

When such a horizontal gene transfer history is found, it's clear that the group of organisms that acquired the gene is evolutionarily younger than the group from which the gene originated. Fournier reasoned that such instances could be used to determine the relative ages between certain bacterial groups. The ages for these groups could then be compared with the ages that various molecular clock models predict. The model that comes closest would likely be the most accurate, and could then be used to precisely estimate the age of other bacterial species -- specifically, cyanobacteria.

Following this reasoning, the team looked for instances of horizontal gene transfer across the genomes of thousands of bacterial species, including cyanobacteria. They also used new cultures of modern cyanobacteria taken by Bosak and Moore, to more precisely use fossil cyanobacteria as calibrations. In the end, they identified 34 clear instances of horizontal gene transfer. They then found that one out of six molecular clock models consistently matched the relative ages identified in the team's horizontal gene transfer analysis.

Fournier ran this model to estimate the age of the "crown" group of cyanobacteria, which encompasses all the species living today and known to exhibit oxygenic photosynthesis. They found that, during the Archean eon, the crown group originated around 2.9 billion years ago, while cyanobacteria as a whole branched off from other bacteria around 3.4 billion years ago. This strongly suggests that oxygenic photosynthesis was already happening 500 million years before the Great Oxidation Event (GOE), and that cyanobacteria were producing oxygen for quite a long time before it accumulated in the atmosphere.

The analysis also revealed that, shortly before the GOE, around 2.4 billion years ago, cyanobacteria experienced a burst of diversification. This implies that a rapid expansion of cyanobacteria may have tipped the Earth into the GOE and launched oxygen into the atmosphere.

Fournier plans to apply horizontal gene transfer beyond cyanobacteria to pin down the origins of other elusive species.

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Major ocean current could warm greatly

A new study led by researchers at Binghamton University, State University of New York found that the Kuroshio Current Extension is sensitive to global climate change and has the potential to warm greatly with increased carbon dioxide levels.

Ocean currents embody motion, snaking their way from the tropics to the poles and back, shifting vast quantities of water from moment to moment. But they are also incredibly old, following their basic course for millions of years.

Tracing a history written in water is the work of paleoceanographers such as Adriane Lam, Presidential Diversity Postdoctoral Fellow in Binghamton University's Department of Geological Sciences and Environmental Studies. Lam is the lead author of "Pliocene to earliest Pleistocene (5-2.5 Ma) Reconstruction of the Kuroshio Current Extension Reveals a Dynamic Current," recently published in the journal Paleoceanography and Paleoclimatology. Co-authors include Assistant Professor of Geological Sciences and Environmental Studies Molly Patterson, as well as Kenneth MacLeod of the University of Missouri, Solveig Schilling of the University of Texas at Austin, R. Mark Leckie of the University of Massachusetts Amherst, Andrew Fraass of England's University of Bristol, and Nicholas Venti of the University of Delaware.

The major western boundary current in the northern Pacific Ocean, the Kuroshio Current and Extension, is analogous to the Gulf Stream, which flows along North America's east coast. Driven by the wind, boundary currents are the workhorses of the ocean, moving heat, salt and gases from the equatorial seas to the middle latitudes, Lam explained.

"In other words, these currents help distribute heat from the tropics to higher latitudes. In fact, corals occur at their highest latitude of anywhere in the world within the Kuroshio Current because the waters are so warm," she said.

That warmth stems from the surface waters that collect in the western Pacific Ocean along the equator, called the Western Pacific Warm Pool. The Kuroshio Current takes these waters north, past the Japanese coast, and then eastward at the 36°N latitude, where it joins the open Pacific Ocean. At this point, it becomes the Kuroshio Current Extension.

The current and extension vent vast amounts of heat and moisture evaporating from the warm water into the lower atmosphere in the Northern Hemisphere. Because of this, they help shape precipitation patterns over Japan and North America's West Coast, as well as the paths of typhoons, which feed off warm waters. In addition to affecting the weather, the Kuroshio also likely affects the climate, although its impact on thousand- and million-year time scales is still unclear.

The Kuroshio also plays a major role in ecosystems and the fishing industry. In the northwest Pacific, it meets the Oyashio Current, which brings the cool waters of the polar region southward. Where the two currents meet, a strong temperature gradient forms due to the mixing of warm and cool waters. It also creates a region of upwelling, where nutrient-rich waters from the deep ocean are brought to the surface as the currents flow eastward.

It's not just the waters that mingle: the warm- and cool-water organisms that live in the respective currents also flow together in a transition area between ecosystems, known as an ecotone. Its inhabitants include several species of fish and plankton, which ultimately power Japan's prolific fishing industry and form a major part of that nation's economy.

Because of their impact on biodiversity, weather and the climate, understanding how boundary currents such as the Kuroshio will respond to climate change and increasing CO2 levels in the atmosphere is critical. Today, these currents are warming two to three times faster than other areas of the ocean, Lam said.

Ocean model studies and observational data also show that the Kuroshio Current Extension is shifting northward and increasing its transport capacity, but researchers don't yet know how these changes will affect the organisms that live there, or local and regional weather and climate patterns.

The recently published research is the first of its kind to reconstruct the Kuroshio as it was 2.5 to 5 million years ago, a time that spanned both periods of global warming and cooling, as well as the closure of a major seaway in what is now Central America. Looking at the current's distant past may answer some of the questions about its future.

Past and future oceans

During the Pliocene, which spans 2.5 to 5.3 million years ago, atmospheric CO2 levels were near those we face today: about 350 to 450 parts per million. Today's atmosphere has about 415 parts per million of CO2.

"The fun part of this time period is that the continents were arranged similar to today, which makes the Pliocene a great time period to use as an analogue as to how the Earth system will respond to increased CO2 concentrations and warming," Lam said.

There were some differences in regard to landmasses, she noted: Until about 2.5 million years ago, a waterway existed between North and South America that allowed surface waters from the Pacific and Atlantic oceans to mingle. When the Central American Seaway closed, it may have brought the Kuroshio Current Extension into its current configuration.

The Pliocene included a period from 3 to 3.3 million years ago known as the mid-Piacenzian Warm Period (mPWP), which saw increased carbon dioxide levels and global warming. Once that period ended, cooling resumed, accompanied by the growth of glaciers and sea ice in the Northern Hemisphere's high latitudes.

In the recently published study, the researchers reconstructed the Kuroshio throughout the mPWP, using chemical signatures from the fossilized shells of marine plankton that once lived in the Kuroshio region's surface waters.

"Our data indicate that during the first phase of mPWP warming in the Pliocene, the current warmed up and potentially shifted its latitudinal position northward. It then cooled back down and perhaps shifted its position back south during a brief period of global cooling," she said.

Reconstructing the current

Scientists use different techniques to reconstruct the history of an ocean current, depending on the time scale in question. For shorter timescales, they rely on observational data to see how a current's path changes seasonally, from year to year or decade to decade. But when it comes to climate change, that dataset can fall short.

"This is why it is useful and necessary to reconstruct the behavior of western boundary currents through deep time, using the sedimentary record from millions of years ago," Lam explained. "Through the lens of the sedimentary record, the shorter-term variations in the current are 'smoothed' or averaged out, so we are essentially only able to recover signals that indicate the longer-term, larger changes of the currents."

In the study, the researchers used the chemical signals obtained from fossil plankton that lived in the surface ocean, as well as three deep-sea sediment cores from Shatsky Rise, a location on the northwest Pacific seafloor. Planktic foraminifera have lived in the open oceans for the last 170 million years; their durable shells, called "tests," are made of calcium carbonate and accumulate on the ocean floor when they die.

In a previous study, Lam calculated the diversity of fossil plankton at each site used in the later chemical study. She found that diversity was highest at the northernmost site of Shatsky Rise, from 12 million years ago until today. This finding indicates the ecotone created by the current has been around for a very long time -- and likely the Kuroshio has, too.

Researchers don't know how warm the current became during the mPWP, or how much the chemical signal is affected by salinity as well as temperature changes. To get a better picture, Lam and colleagues from other SUNY schools are currently working on a grant that would use different chemical methods to answer these questions.

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'Is that a bacon sandwich?' Fruit flies react to smells while asleep

Researchers have tracked flies' ability to interpret information while asleep, showing which parts of the brain remain 'awake'.

The study, led by Imperial College London researchers and published today in Nature, is the first to show how an animal brain subconsciously processes 'salient' information that requires interpretation, such as smells.

While we sleep, we can react to two kinds of stimulus. Quantitative information, like a loud noise or a slap in the face, requires no special processing to wake us up. However, qualitative or 'salient' information requires us to do some subconscious processing -- for example, if someone is speaking, are they calling our name? Or is that wail our baby crying?

Although the phenomenon has been recognised in humans, it is much more difficult to track the processing in a human brain due to its complexity. However, for fruit flies the entire 'connectome' -- the map of neurons and their connections in the brain -- has been defined, allowing researchers for the first time to determine which parts of the brain are involved in salient subconscious processing.

First author Dr Alice French, from the Department of Life Sciences at Imperial, said: "Sleep puts you in a vulnerable position, such as being at risk of predation. Therefore, animals, including humans, need to be able to respond to potential threats so that they wake up and act. If it's a sound, like a loud bang, the processing our brains need to do is relatively simple.

"However, to actively decode the sounds and smells around us that may or may not be relevant to us, different parts of the brain must remain alert. Now, in fruit flies, who share more in common with us than you might think, we have discovered one region of the sleeping brain stays awake to process smells."

The team tested well-fed and rested fruit flies' response to dozens of odours, finding that aversive ones woke the flies up more often than attractive ones.

The researchers were able to test thousands of flies using their 'ethoscope' setup, where flies are placed individually in tubes and monitored by an automatic camera system. Once the system detects a fly is asleep, a puff of odour is released, and the system records whether the fly responds.

The team then tracked the neurons involved with fluorescent markers, following the chain of highlighted neurons from the antennae (the fly nose) to the brain region involved in sleep regulation. They were able to confirm their conclusions by switching on and off some of the highlighted neurons, affecting the flies' ability to detect odours.

The researchers also took their study further, asking whether the flies' response to salient information was fixed or 'plastic' -- would it be different under different circumstances? In humans, this is observed for example when people sleep in an unfamiliar place, making them more sensitive to external stimuli while they sleep.

For the flies, the researchers changed several factors they thought might affect their response to odours, including starvation during the day, sleep deprivation, and drunkenness. Drunk and sleep-deprived flies were less responsive overall to odours, but the starved flies were more responsive specifically to food-related odours.

Lead researcher Dr Giorgio Gilestro, from the Department of Life Sciences at Imperial, said: "Sleep is always a trade-off -- while asleep you are vulnerable to predators and you can't collect food or mate -- so it must be important, but we don't know exactly why. While all animals sleep, its character differs across the animal kingdom.

"Fruit flies are the ideal study subjects because they exhibit complex behaviours, including sleep, but have relatively simple brains, allowing us to investigate the roots of this common behaviour. However, even in fruit flies, different species have different levels of sleep and wakefulness. Investigating how different animals balance their needs can help us determine the ultimate function of sleep."

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This is what it looks like when a black hole snacks on a star

While black holes and toddlers don't seem to have much in common, they are remarkably similar in one aspect: Both are messy eaters, generating ample evidence that a meal has taken place.

But whereas one might leave behind droppings of pasta or splatters of yogurt, the other creates an aftermath of mind-boggling proportions. When a black hole gobbles up a star, it produces what astronomers call a "tidal disruption event." The shredding of the hapless star is accompanied by an outburst of radiation that can outshine the combined light of every star in the black hole's host galaxy for months, even years.

In a paper published in The Astrophysical Journal, a team of astronomers led by Sixiang Wen, a postdoctoral research associate at the University of Arizona Steward Observatory, use the X-rays emitted by a tidal disruption event known as J2150 to make the first measurements of both the black hole's mass and spin. This black hole is of a particular type -- an intermediate-mass black hole -- which has long eluded observation.

"The fact that we were able to catch this black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible," said Ann Zabludoff, UArizona professor of astronomy and co-author on the paper. "Not only that, by analyzing the flare we were able to better understand this elusive category of black holes, which may well account for the majority of black holes in the centers of galaxies."

By re-analyzing the X-ray data used to observe the J2150 flare, and comparing it with sophisticated theoretical models, the authors showed that this flare did indeed originate from an encounter between an unlucky star and an intermediate-mass black hole. The intermediate black hole in question is of particularly low mass -- for a black hole, that is -- weighing in at roughly 10,000 times the mass of the sun.

"The X-ray emissions from the inner disk formed by the debris of the dead star made it possible for us to infer the mass and spin of this black hole and classify it as an intermediate black hole," Wen said.

Dozens of tidal disruption events have been seen in the centers of large galaxies hosting supermassive black holes, and a handful have also been observed in the centers of small galaxies that might contain intermediate black holes. However, past data has never been detailed enough to prove that an individual tidal disruption flare was powered by an intermediate black hole.

"Thanks to modern astronomical observations, we know that the centers of almost all galaxies that are similar to or larger in size than our Milky Way host central supermassive black holes," said study co-author Nicholas Stone, a senior lecturer at Hebrew University in Jerusalem. "These behemoths range in size from 1 million to 10 billion times the mass of our sun, and they become powerful sources of electromagnetic radiation when too much interstellar gas falls into their vicinity."

The mass of these black holes correlates closely with the total mass of their host galaxies; the largest galaxies host the largest supermassive black holes.

"We still know very little about the existence of black holes in the centers of galaxies smaller than the Milky Way," said co-author Peter Jonker of Radboud University and SRON Netherlands Institute for Space Research, both in the Netherlands. "Due to observational limitations, it is challenging to discover central black holes much smaller than 1 million solar masses."

Despite their presumed abundance, the origins of supermassive black holes remain unknown, and many different theories currently vie to explain them, according to Jonker. Intermediate-mass black holes could be the seeds from which supermassive black holes grow.

"Therefore, if we get a better handle of how many bona fide intermediate black holes are out there, it can help determine which theories of supermassive black hole formation are correct," he said.

Even more exciting, according to Zabludoff, is the measurement of J2150's spin that the group was able to obtain. The spin measurement holds clues as to how black holes grow, and possibly to particle physics.

This black hole has a fast spin, but not the fastest possible spin, Zabludoff explained, begging the question of how the black hole ends up with a spin in this range.

"It's possible that the black hole formed that way and hasn't changed much since, or that two intermediate-mass black holes merged recently to form this one," she said. "We do know that the spin we measured excludes scenarios where the black hole grows over a long time from steadily eating gas or from many quick gas snacks that arrive from random directions."

In addition, the spin measurement allows astrophysicists to test hypotheses about the nature of dark matter, which is thought to make up most of the matter in the universe. Dark matter may consist of unknown elementary particles not yet seen in laboratory experiments. Among the candidates are hypothetical particles known as ultralight bosons, Stone explained.

"If those particles exist and have masses in a certain range, they will prevent an intermediate-mass black hole from having a fast spin," he said. "Yet J2150's black hole is spinning fast. So, our spin measurement rules out a broad class of ultralight boson theories, showcasing the value of black holes as extraterrestrial laboratories for particle physics."

In the future, new observations of tidal disruption flares might let astronomers fill in the gaps in the black hole mass distribution, the authors hope.

"If it turns out that most dwarf galaxies contain intermediate-mass black holes, then they will dominate the rate of stellar tidal disruption," Stone said. "By fitting the X-ray emission from these flares to theoretical models, we can conduct a census of the intermediate-mass black hole population in the universe," Wen added.

To do that, however, more tidal disruption events have to be observed. That's why astronomers hold high hopes for new telescopes coming online soon, both on Earth and in space, including the Vera C. Rubin Observatory, also known as the Legacy Survey of Space and Time, or LSST, which is expected to discover thousands of tidal disruption events per year.

Read more at Science Daily

Answering a century-old question on the origins of life

The missing link isn't a not-yet-discovered fossil, after all. It's a tiny, self-replicating globule called a coacervate droplet, developed by two researchers in Japan to represent the evolution of chemistry into biology.

They published their results on September 24 in the Nature Communications.

"Chemical evolution was first proposed in the 1920s as the idea that life first originated with the formation of macromolecules from simple small molecules, and those macromolecules formed molecular assemblies that could proliferate," said first-author Muneyuki Matsuo, assistant professor of chemistry in the Graduate School of Integrated Sciences for Life at Hiroshima University. "Since then, many studies have been conducted to verify the RNA world hypothesis -- where only self-replicating genetic material existed prior to the evolution of DNA and proteins -- experimentally. However, the origin of molecular assemblies that proliferate from small molecules has remained a mystery for about a hundred years since the advent of the chemical evolution scenario. It has been the missing link between chemistry and biology in the origin of life."

Matsuo partnered with Kensuke Kurihara, researcher at KYOCERA Corporation, to answer the century-old question: how did the free-form chemicals of early Earth become life? Like many researchers, they initially thought it came down to the environment: the ingredients formed under high pressure and temperature, then cooled into more life-friendly conditions. The issue was propagation.

"Proliferation requires spontaneous polymer production and self-assembly under the same conditions," Matsuo said.

They designed and synthesized a new prebiotic monomer from amino acid derivatives as a precursor to the self-assembly of primitive cells. When added to room temperature water at atmospheric pressure, the amino acid derivatives condensed, arranging into peptides, which then spontaneously formed droplets. The droplets grew in size and in number when fed with more amino acids. The researchers also found that the droplets could concentrate nucleic acids -- genetic material -- and they were more likely to survive against external stimuli if they exhibited this function.

"A droplet-based protocell could have served as a link between 'chemistry' and 'biology' during the origins of life," Matsuo said. "This study may serve to explain the emergence of the first living organisms on primordial Earth."

The researchers plan to continue investigating the process of evolution from amino acid derivatives to primitive living cells, as well as improve their platform to verify and study the origins of life and continued evolution.

Read more at Science Daily

Cosmic impact destroyed a biblical city in Jordan Valley

In the Middle Bronze Age (about 3600 years ago or roughly 1650 BCE), the city of Tall el-Hammam was ascendant. Located on high ground in the southern Jordan Valley, northeast of the Dead Sea, the settlement in its time had become the largest continuously occupied Bronze Age city in the southern Levant, having hosted early civilization for a few thousand years. At that time, it was 10 times larger than Jerusalem and 5 times larger than Jericho.

"It's an incredibly culturally important area," said James Kennett, emeritus professor of earth science at the UC Santa Barbara. "Much of where the early cultural complexity of humans developed is in this general area."

A favorite site for archaeologists and biblical scholars, the mound hosts evidence of culture all the way from the Chalcolithic, or Copper Age, all compacted into layers as the highly strategic settlement was built, destroyed, and rebuilt over millennia.

But there is a 1.5-meter interval in the Middle Bronze Age II stratum that caught the interest of some researchers, for its "highly unusual" materials. In addition to the debris one would expect from destruction via warfare and earthquakes, they found pottery shards with outer surfaces melted into glass, "bubbled" mudbrick, and partially melted building material, all indications of an anomalously high-temperature event, much hotter than anything the technology of the time could produce.

"We saw evidence for temperatures greater than 2,000 degrees Celsius," said Kennett, whose research group at the time happened to have been building the case for an older cosmic airburst about 12,800 years ago that triggered major widespread burning, climatic changes and animal extinctions. The charred and melted materials at Tall el-Hammam looked familiar, and a group of researchers including impact scientist Allen West and Kennett joined Trinity Southwest University biblical scholar Philip J. Silvia's research effort to determine what happened at this city 3,650 years ago.

Their results are published in the journal Nature Scientific Reports.

Salt and Bone

"There's evidence of a large cosmic airburst, close to this city called Tall el-Hammam," Kennett said, of an explosion similar to the Tunguska Event, a roughly 12-megaton airburst that occurred in 1908, when a 56-60-meter meteor pierced the Earth's atmosphere over the Eastern Siberian Taiga.

The shock of the explosion over Tall el-Hammam was enough to level the city, flattening the palace and surrounding walls and mudbrick structures, according to the paper, and the distribution of bones indicated "extreme disarticulation and skeletal fragmentation in nearby humans."

For Kennett, further proof of the airburst was found by conducting many different kinds of analyses on soil and sediments from the critical layer. Tiny iron- and silica-rich spherules turned up in their analysis, as did melted metals.

"I think one of the main discoveries is shocked quartz. These are sand grains containing cracks that form only under very high pressure," Kennett said of one of many lines of evidence that point to a large airburst near Tall el-Hammam. "We have shocked quartz from this layer, and that means there were incredible pressures involved to shock the quartz crystals -- quartz is one of the hardest minerals; it's very hard to shock."

The airburst, according to the paper, may also explain the "anomalously high concentrations of salt" found in the destruction layer -- an average of 4% in the sediment and as high as 25% in some samples.

"The salt was thrown up due to the high impact pressures," Kennett said, of the meteor that likely fragmented upon contact with the Earth's atmosphere. "And it may be that the impact partially hit the Dead Sea, which is rich in salt." The local shores of the Dead Sea are also salt-rich so the impact may have redistributed those salt crystals far and wide -- not just at Tall el-Hammam, but also nearby Tell es-Sultan (proposed as the biblical Jericho, which also underwent violent destruction at the same time) and Tall-Nimrin (also then destroyed).

The high-salinity soil could have been responsible for the so-called "Late Bronze Age Gap," the researchers say, in which cities along the lower Jordan Valley were abandoned, dropping the population from tens of thousands to maybe a few hundred nomads. Nothing could grow in these formerly fertile grounds, forcing people to leave the area for centuries. Evidence for resettlement of Tall el-Hammam and nearby communities appears again in the Iron Age, roughly 600 years after the cities' sudden devastation in the Bronze Age.

Fire and Brimstone

Tall el-Hamman has been the focus of an ongoing debate as to whether it could be the biblical city of Sodom, one of the two cities in the Old Testament Book of Genesis that were purportedly destroyed by God for how wicked the cities and their inhabitants had become. According to the story, one denizen, Lot, is saved by two angels who instruct him not to look behind as they flee. Lot's wife, however, lingers and is turned into a pillar of salt. Meanwhile, fire and brimstone fell from the sky; multiple cities were destroyed; thick smoke rose from the fires; city inhabitants were killed and area crops were destroyed in what sounds like an eyewitness account of a cosmic impact event.

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Sunlight exposure guidelines may need to be revised

Previously published solar exposure guidelines for optimal vitamin D synthesis based on a study of skin samples may need to be revised, according to new research published today in PNAS.

A study by researchers from King's College London, with support from the NIHR Guy's and St Thomas' Biomedical Research Centre, has tested the optimum ultraviolet radiation (UVR) wavelengths for human skin production of vitamin D in sunlight.

UVR from sunlight can cause sunburn and skin cancer, however, it is the most important source of vitamin D that is essential for healthy bone development and maintenance.

Public health advice on sunlight exposure takes both risk and benefits into account. Calculating the potential risks and benefits from sunlight exposure is not simple because the health outcomes from UVR exposure vary considerably with wavelength within the sun's UVR spectrum. For example, the sun's UVR contains less than 5% short wavelength UVB radiation but this is responsible for over 80% of the sunburn response. Each health outcome from solar exposure has its own unique wavelength dependency.

The association between specific UVB wavelengths and vitamin D production was determined more than thirty years ago in skin samples (ex vivo). However, the finding is less well established and there have been doubts about its accuracy. These doubts compromise risk/benefit calculations for optimal solar exposure.

Researchers led by the Professor Antony Young from King's College London measured blood vitamin D levels in 75 healthy young volunteers, before, during, and after partial or full body exposure to five different artificial UVR sources with different amounts of UVB radiation, to weigh the trade-off between the benefits of solar exposure, which include vitamin D synthesis, versus the risks of sunburn and skin cancer.

They then compared their results with those that would be predicted from the old ex vivo vitamin D study and found the previous study is not an accurate predictor of benefit from UVR exposure.

The authors recommend a simple systematic correction of the ex vivo wavelength dependency for vitamin D. The new study means that many risk benefit calculations for solar UVR exposure must be reviewed with a revised version of the wavelength dependency for vitamin D.

Read more at Science Daily

Earth and Venus grew up as rambunctious planets

Planet formation -- the process by which neat, round, distinct planets form from a roiling, swirling cloud of rugged asteroids and mini planets -- was likely even messier and more complicated than most scientists would care to admit, according to new research led by researchers at the University of Arizona Lunar and Planetary Laboratory.

The findings challenge the conventional view, in which collisions between smaller building blocks cause them to stick together and, over time, repeated collisions accrete new material to the growing baby planet.

Instead, the authors propose and demonstrate evidence for a novel "hit-and-run-return" scenario, in which pre-planetary bodies spent a good part of their journey through the inner solar system crashing into and ricocheting off of each other, before running into each other again at a later time. Having been slowed down by their first collision, they would be more likely to stick together the next time. Picture a game of billiards, with the balls coming to rest, as opposed to pelting a snowman with snowballs, and you get the idea.

The research is published in two reports appearing in the Sept. 23 issue of The Planetary Science Journal, with one focusing on Venus and Earth, and the other on Earth's moon. Central to both publications, according to the author team, which was led by planetary sciences and LPL professor Erik Asphaug, is the largely unrecognized point that giant impacts are not the efficient mergers scientists believed them to be.

"We find that most giant impacts, even relatively 'slow' ones, are hit-and-runs. This means that for two planets to merge, you usually first have to slow them down in a hit-and-run collision," Asphaug said. "To think of giant impacts, for instance the formation of the moon, as a singular event is probably wrong. More likely it took two collisions in a row."

One implication is that Venus and Earth would have had very different experiences in their growth as planets, despite being immediate neighbors in the inner solar system. In the first paper, led by Alexandre Emsenhuber, who did this work during a postdoctoral fellowship in Asphaug's lab and is now at Ludwig Maximilian University in Munich, the young Earth would have served to slow down interloping planetary bodies, making them ultimately more likely to collide with and stick to Venus.

"We think that during solar system formation, the early Earth acted like a vanguard for Venus," Emsenhuber said.

The solar system is what scientists call a gravity well, the concept behind a popular attraction at science exhibits. Visitors toss a coin into a funnel-shaped gravity well, and then watch their cash complete several orbits before it drops into the center hole. The closer a planet is to the sun, the stronger the gravitation experienced by planets. That's why the inner planets of the solar system on which these studies were focused -- Mercury, Venus, Earth and Mars -- orbit the sun faster than, say, Jupiter, Saturn and Neptune. As a result, the closer an object ventures to the sun, the more likely it is to stay there.

So when an interloping planet hit the Earth, it was less likely to stick to Earth, and instead more likely to end up at Venus, Asphaug explained.

"The Earth acts as a shield, providing a first stop against these impacting planets," he said. "More likely than not, a planet that bounces off of Earth is going to hit Venus and merge with it."

Emsenhuber uses the analogy of a ball bouncing down a staircase to illustrate the idea of what drives the vanguard effect: A body coming in from the outer solar system is like a ball bouncing down a set of stairs, with each bounce representing a collision with another body.

"Along the way, the ball loses energy, and you'll find it will always bounce downstairs, never upstairs," he said. "Because of that, the body cannot leave the inner solar system anymore. You generally only go downstairs, toward Venus, and an impactor that collides with Venus is pretty happy staying in the inner solar system, so at some point it is going to hit Venus again."

Earth has no such vanguard to slow down its interloping planets. This leads to a difference between the two similar-sized planets that conventional theories cannot explain, the authors argue.

"The prevailing idea has been that it doesn't really matter if planets collide and don't merge right away, because they are going to run into each other again at some point and merge then," Emsenhuber said. "But that is not what we find. We find they end up more frequently becoming part of Venus, instead of returning back to Earth. It's easier to go from Earth to Venus than the other way around."

To track all these planetary orbits and collisions, and ultimately their mergers, the team used machine learning to obtain predictive models from 3D simulations of giant impacts. The team then used these data to rapidly compute the orbital evolution, including hit-and-run and merging collisions, to simulate terrestrial planet formation over the course of 100 million years. In the second paper, the authors propose and demonstrate their hit-and-run-return scenario for the moon's formation, recognizing the primary problems with the standard giant impact model.

"The standard model for the moon requires a very slow collision, relatively speaking," Asphaug said, "and it creates a moon that is composed mostly of the impacting planet, not the proto-Earth, which is a major problem since the moon has an isotopic chemistry almost identical to Earth."

In the team's new scenario, a roughly Mars-sized protoplanet hits the Earth, as in the standard model, but is a bit faster so it keeps going. It returns in about 1 million years for a giant impact that looks a lot like the standard model.

"The double impact mixes things up much more than a single event," Asphaug said, "which could explain the isotopic similarity of Earth and moon, and also how the second, slow, merging collision would have happened in the first place."

The researchers think the resulting asymmetry in how the planets were put together points the way to future studies addressing the diversity of terrestrial planets. For example, we don't understand how Earth ended up with a magnetic field that is much stronger than that of Venus, or why Venus has no moon.

Their research indicates systematic differences in dynamics and composition, according to Asphaug.

"In our view, Earth would have accreted most of its material from collisions that were head-on hits, or else slower than those experienced by Venus," he said. "Collisions into the Earth that were more oblique and higher velocity would have preferentially ended up on Venus."

This would create a bias in which, for example, protoplanets from the outer solar system, at higher velocity, would have preferentially accreted to Venus instead of Earth. In short, Venus could be composed of material that was harder for the Earth to get ahold of.

"You would think that Earth is made up more of material from the outer system because it is closer to the outer solar system than Venus. But actually, with Earth in this vanguard role, it makes it actually more likely for Venus to accrete outer solar system material," Asphaug said.

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Hyena scavenging provides public health and economic benefits to African cities

Hyenas are frequently vilified and often feared. Hemingway once described the hyena as a stinking, foul devourer of the dead, with jaws that crack the bones the lion leaves.

But a new study concludes that spotted hyena scavenging provides significant public health and economic benefits to the African cities they roam.

In a study conducted in and around the Ethiopian city of Mekelle, home to 310,000 people and 120,000 livestock animals, a University of Michigan conservation ecologist and two colleagues found that spotted hyenas annually remove 207 tons of animal carcass waste.

Mekelle is the capital of northern Ethiopia's Tigray region. The carcasses of livestock animals that are slaughtered for food there, or that die naturally, are often dumped at the local landfill or on roadsides, where hyenas feed on the waste. The researchers wanted to know whether hyenas -- by removing this waste from the environment -- might also prevent pathogens from jumping into people and livestock.

They determined that hyena scavenging annually prevents five infections of anthrax and bovine tuberculosis in Mekelle residents and 140 infections in cattle, sheep and goats. This disease-control service potentially saves the city $52,000 annually in treatment costs and livestock losses avoided.

The study, published online Sept. 26 in the Journal of Applied Ecology, is the first to quantify the public health and economic benefits of scavenging by spotted hyenas.

"Yes, the effects are modest. Even so, this study totally upends the traditional narrative around hyenas -- that they are a nuisance and should be removed," said U-M's Neil Carter, senior author of the study and an assistant professor at the School for Environment and Sustainability. "This is an important contribution to a growing body of work that highlights the benefits of predators and scavengers, rather than focusing only on their costs to humanity."

The authors emphasize that these sanitation and disease-control services are particularly valuable in low-income and rural areas. In Mekelle, the scavenging behavior of hyenas advances three U.N. Sustainable Development Goals: ensuring good health and well-being, providing clean water and sanitation, and promoting terrestrial biodiversity.

To estimate the benefits of spotted hyenas, the researchers examined their feeding habits and the population size around Mekelle. During the daytime, the Mekelle hyenas rest at sites outside the city to avoid human disturbances; they come into the city at night to feed.

The field data were collected and analyzed by study lead author Chinmay Sonawane, a former student of Carter's who is now a doctoral student at Stanford University.

Those data were integrated into a disease transmission model used to predict the number of anthrax and bovine tuberculosis infections arising in humans and livestock from infected carcass waste, as well as the costs associated with treating those infections and losing livestock. The researchers compared these public health and economic outcomes under two scenarios: hyenas present and hyenas absent.

"In comparison to the large cattle enterprises in the Global North, the benefits that we found are quite small," Sonawane said. "However, losing even a single cow to anthrax or bovine tuberculosis can cause significant financial stress to cattle owners in Ethiopia, who tend to own much smaller herds of cattle than cattle owners in other parts of the world.

"In addition, we only estimated the benefits accrued from hyenas within 5 kilometers of the city. It is very, very likely that hyenas much further than 5 kilometers are coming into Mekelle and consuming even more waste."

For Sonawane, the fieldwork involved spending nights at the Mekelle landfill and recording the number and type of animal carcasses (mostly cattle, horses, chickens, sheep and goats) available to the scavengers.

He counted the hyenas and watched them feed, using night-vision binoculars that operate at infrared wavelengths. The black-and-white photos and video clips he captured are haunting: the eyes of the hyenas glow with an unearthly fire.

The study authors determined that an individual Mekelle hyena annually scavenges about 2,100 pounds of carcass waste around the city. For hyenas feeding at the landfill, horse carcasses accounted for about 80% of that total, while poultry waste was the most frequently consumed type of animal carcass waste.

The researchers estimated a population size of 210 hyenas around Mekelle using "call-in surveys." This field method involved broadcasting prerecorded hyena distress calls with a 45-watt megaphone from the top of a vehicle at five locations around the city. During each hour-long survey, the researchers counted the number of hyenas attracted to the sounds and visible with the night-vision binoculars.

Given the consumption rate and the estimated population size, the Mekelle hyenas were expected to annually remove 207 metric tons of animal carcass waste, which is 4.2% of the total animal carcass waste thrown away by residents and businesses.

Waste generation in Mekelle is expected to increase with the exponentially growing human population there, Carter and his colleagues wrote: "Given the financial constraints on waste collection and disposal services, sanitary conditions are expected to deteriorate further." Hyena scavenging may, therefore, be even more valuable in the future.

The authors note that the benefits of hyena presence must be weighed against the costs. A 2011 study reported 10 nonfatal hyena attacks on humans annually in Mekelle, along with an estimated economic loss of $2,928 from 33 fatal attacks on cattle and small ruminants annually.

To preserve the public health and financial benefits provided by hyenas into the future, nonlethal management actions that minimize risks and enable hyenas to coexist with humans are necessary, according to the authors.

"By maintaining the hyenas' access to waste, human-hyena conflict can be mitigated in Mekelle, and the sanitation and disease control benefits provided by hyena scavenging can be preserved or even increased," they wrote.

But excluding hyenas from scavenging animal carcass waste may compel them to hunt livestock and could increase human-hyena conflict, as a previous study in Mekelle has shown.

Read more at Science Daily

The origin and legacy of the Etruscans

The Etruscan civilization, which flourished during the Iron Age in central Italy, has intrigued scholars for millennia. With remarkable metallurgical skills and a now-extinct, non-Indo-European language, the Etruscans stood out from their contemporary neighbors, leading to intense debate from the likes of the ancient Greek historian Herodotus on their geographical origins.

Now, a new study by a team of scholars from Germany, Italy, USA, Denmark and the UK, sheds light on the origin and legacy of the enigmatic Etruscans with genome-wide data from 82 ancient individuals from central and southern Italy, spanning 800 BCE to 1000 CE. Their results show that the Etruscans, despite their unique cultural expressions, were closely related to their italic neighbors, and reveal major genetic transformations associated with historical events.

An intriguing phenomenon

With an extinct language that is only partly understood, much of what was initially known about Etruscan civilization comes from the commentary of later Greek and Roman writers. One hypothesis about their origins, the one favored by Herodotus, points to the influence of ancient Greek cultural elements to argue that the Etruscans descended from migrating Anatolian or Aegean groups. Another, championed by Dionysius of Halicarnassus, proposes that the Etruscans originated and developed locally from the Bronze Age Villanovan culture and were therefore an autochthonous population.

Although the current consensus among archaeologists supports a local origin for the Etruscans, a lack of ancient DNA from the region has made genetic investigations inconsistent. The current study, with a time transect of ancient genomic information spanning almost 2000 years collected from 12 archaeological sites, resolves lingering questions about Etruscan origins, showing no evidence for a recent population movement from Anatolia. In fact, the Etruscans shared the genetic profile of the Latins living in nearby Rome, with a large proportion of their genetic profiles coming from steppe-related ancestry that arrived in the region during the Bronze Age.

Considering that steppe-related groups were likely responsible for the spread of Indo-European languages, now spoken around the world by billions of people, the persistence of a non-Indo-European Etruscan language is an intriguing and still unexplained phenomenon that will require further archaeological, historical, linguistic and genetic investigation.

"This linguistic persistence, combined with a genetic turnover, challenges simple assumptions that genes equal languages and suggests a more complex scenario that may have involved the assimilation of early Italic speakers by the Etruscan speech community, possibly during a prolonged period of admixture over the second millennium BCE," says David Caramelli, Professor at the University of Florence.

Periods of change

Despite a few individuals of eastern Mediterranean, northern African, and central Europeanorigins, the Etruscan-related gene pool remained stable for at least 800 years, spanning the Iron Age and Roman Republic period. The study finds, however, that during the subsequent Roman Imperial period, central Italy experienced a large scale genetic shift, resulting from admixture with eastern Mediterranean populations, which likely included slaves and soldiers relocated across the Roman Empire.

"This genetic shift clearly depicts the role of the Roman Empire in the large-scale displacement of people in a time of enhanced upward or downward socioeconomic and geographic mobility," says Johannes Krause, Director at the Max Planck Institute for Evolutionary Anthropology.

Looking at the more recent Early Middle Ages, the researchers identified northern European ancestries spreading across the Italian peninsula following the collapse of the Western Roman Empire. These results suggest that Germanic migrants, including individuals associated with the newly established Longobard Kingdom, might have left a traceable impact on the genetic landscape of central Italy.

In the regions of Tuscany, Lazio, and Basilicata the population's ancestry remained largely continuous between the Early Medieval times and today, suggesting that the main gene pool of present-day people from central and southern Italy was largely formed at least 1000 years ago.

Although more ancient DNA from across Italy is needed to support the above conclusions, ancestry shifts in Tuscany and northern Lazio similar to those reported for the city of Rome and its surroundings suggests that historical events during the first millennium CE had a major impact on the genetic transformations over much of the Italian peninsula.

Read more at Science Daily

Spouses really are together in sickness and in health suggests new study

A couple's health is surprisingly intertwined according to a recent cohort study that looked at Dutch and Japanese marriages.

The study discovered that spouses have a high degree of commonality in not only lifestyle habits, but body shape, blood pressure, and even incidence of some diseases.

When it comes to marriage, the adage "birds of a feather flock together" is relatively true. Previous studies have indicated that we gravitate towards people of similar social class, educational background, race, and weight. The scientific name for this is assertive mating, and it means that spouses are often genetically similar. This allows researchers to explore environmental factors in greater detail.

Researchers examined 5,391 pairs from Japan and 28,265 from the Netherlands, drawing on data from the Tohoku Medical Megabank Project, and the Lifelines study in the Netherlands.

Couples from both countries shared similar lifestyle habits and physical traits such as smoking, drinking, weight, abdominal circumference, and body mass index. When the researchers dived further into the data, they determined that couples had corresponding blood pressure, cholesterol, and triglycerides levels. Moreover, related incidents of hypertension, diabetes, and metabolic syndrome were also found.

Many of the correlations were between couples with low genetic similarity and high lifestyle similarity, suggesting the importance of healthy choices. The researchers encourage healthcare guidance for couples and a healthy dose of competition between partners that encourages each other to improve their health, especially against diseases shaped by lifestyle and environment.

So, the next time you go for a checkup, why not bring your partner? Better yet, challenge them to a walk to the clinic.

From Science Daily

Gamma rays and neutrinos from mellow supermassive black holes

The Universe is filled with energetic particles, such as X rays, gamma rays, and neutrinos. However, most of the high-energy cosmic particles' origins remain unexplained.

Now, an international research team has proposed a scenario that explains these; black holes with low activity act as major factories of high-energy cosmic particles.

Details of their research were published in the journal Nature Communications.

Gamma rays are high-energy photons that are many orders of magnitude more energetic than visible light. Space satellites have detected cosmic gamma rays with energies of megaelectron to gigaelectron volts.

Neutrinos are subatomic particles whose mass is nearly zero. They rarely interact with ordinary matter. Researchers at the IceCube Neutrino Observatory have also measured high-energy cosmic neutrinos.

Both gamma rays and neutrinos should be created by powerful cosmic-ray accelerators or surrounding environments in the Universe. However, their origins are still unknown. It is widely believed that active supermassive black holes (so-called active galactic nuclei), especially those with powerful jets, are the most promising emitters of high-energy gamma rays and neutrinos. However, recent studies have revealed that they do not explain the observed gamma rays and neutrinos, suggesting that other source classes are necessary.

The new model shows that not only active black holes but also non-active, "mellow" ones are important, acting as gamma-ray and neutrino factories.

All galaxies are expected to contain supermassive black holes at their centers. When matter falls into a black hole, a huge amount of gravitational energy is released. This process heats the gas, forming high-temperature plasma. The temperature can reach as high as tens of billions of Celsius degrees for low-accreting black holes because of inefficient cooling, and the plasma can generate gamma rays in the megaelectron volt range.

Such mellow black holes are dim as individual objects, but they are numerous in the Universe. The research team found that the resulting gamma rays from low-accreting supermassive black holes may contribute significantly to the observed gamma rays in the megaelectron volt range.

In the plasma, protons can be accelerated to energies roughly 10,000 times higher than those achieved by the Large Hadron Collider -- the largest human-made particle accelerator. The sped-up protons produce high-energy neutrinos through interactions with matter and radiation, which can account for the higher-energy part of the cosmic neutrino data. This picture can be applied to active black holes as demonstrated by previous research. The supermassive black holes including both active and non-active galactic nuclei can explain a large fraction of the observed IceCube neutrinos in a wide energy range.

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An experimental loop for simulating nuclear reactors in space

Nuclear thermal propulsion, which uses heat from nuclear reactions as fuel, could be used one day in human spaceflight, possibly even for missions to Mars. Its development, however, poses a challenge. The materials used must be able to withstand high heat and bombardment of high-energy particles on a regular basis.

Will Searight, a nuclear engineering doctoral student at penn State, is contributing to research that could make these advancements more feasible. He published findings from a preliminary design simulation in Fusion Science and Technology, a publication of the American Nuclear Society.

To better investigate nuclear thermal propulsion, Searight simulated a small-scale laboratory experiment known as a hydrogen test loop. The setup mimics a reactor's operation in space, where flowing hydrogen travels through?the core and propels the rocket -- at temperatures up to nearly 2,200 degrees Fahrenheit. Searight developed the simulation using dimensions from detailed drawings of tie tubes, the components that make up much of the test loop through which hydrogen flows. Industry partner Ultra Safe Nuclear Corporation (USNC) provided the drawings.

"Understanding how USNC's components behave in a hot hydrogen environment is crucial to bringing our rockets to space," Searight said. "We're thrilled to be working with one of the main reactor contractors for NASA's space nuclear propulsion project, which is seeking to produce a demonstration nuclear thermal propulsion engine within a decade."

Advised by Leigh Winfrey, associate professor and undergraduate program chair of nuclear engineering, Searight used Ansys Fluent, a modeling software, to design a simulation loop from a stainless steel pipe with an outer diameter of about two inches. In the model, the loop connects to a hydrogen pump and circulates hot hydrogen through a test section adjacent to a heating element.

Searight found that while consistent heating of hydrogen to 2,200 degrees Fahrenheit was possible, it was necessary to include a heating element directly above the test section to prevent a reduction in heating. Data collected from the modeling software showed that the flow of hydrogen through the test section was smooth and uniform, reducing uneven distribution of heat through the loop that could jeopardize the setup's safety and lifespan. Analysis of the results also verified that stainless steel would allow for more convenient and cost-effective construction of the loop.

"We are excited to take the first steps in developing a unique capability for extreme environment simulation at Penn State," Winfrey said. "This preliminary work will enable us to pursue research that could have a major impact on the future of space exploration."

With further research, Searight's preliminary work could enable expanded testing of materials that could one day be implemented to create faster, more efficient space travel using reactor-fueled rockets.

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