Megalith tombs were family graves in European Stone Age

The Ansarve site on the island of Gotland in the Baltic Sea is embedded in an area with mostly hunter-gathers at the time.

In a new study published in the Proceedings of the National Academy of Sciences, an international research team, led from Uppsala University, discovered kin relationships among Stone Age individuals buried in megalithic tombs on Ireland and in Sweden. The kin relations can be traced for more than ten generations and suggests that megaliths were graves for kindred groups in Stone Age northwestern Europe.

Agriculture spread with migrants from the Fertile Crescent into Europe around 9,000 BCE, reaching northwestern Europe by 4,000 BCE. Starting around 4,500 BCE, a new phenomenon of constructing megalithic monuments, particularly for funerary practices, emerged along the Atlantic façade. These constructions have been enigmatic to the scientific community, and the origin and social structure of the groups that erected them has remained largely unknown. The international team sequenced and analysed the genomes from the human remains of 24 individuals from five megalithic burial sites, encompassing the widespread tradition of megalithic construction in northern and western Europe.

The team collected human remains of 24 individuals from megaliths on Ireland, in Scotland and the Baltic island of Gotland, Sweden. The remains were radiocarbon-dated to between 3,800 and 2,600 BCE. DNA was extracted from bones and teeth for genome sequencing. The team compared the genomic data to the genetic variation of Stone Age groups and individuals from other parts of Europe. The individuals in the megaliths were closely related to Neolithic farmers in northern and western Europe, and also to some groups in Iberia, but less related to farmer groups in central Europe.

The team found an overrepresentation of males compared to females in the megalith tombs on the British Isles.

"We found paternal continuity through time, including the same Y-chromosome haplotypes reoccurring over and over again," says archaeogeneticist Helena Malmström of Uppsala University and co-first author. "However, female kindred members were not excluded from the megalith burials as three of the six kinship relationships in these megaliths involved females."

The genetic data show close kin relationships among the individuals buried within the megaliths. A likely parent-offspring relation was discovered for individuals in the Listhogil Tomb at the Carrowmore site and Tomb 1 at Primrose Grange, about 2 km distance away from each other. "This came as a surprise. It appears as these Neolithic societies were tightly knit with very close kin relations across burial sites," says population-geneticist Federico Sanchez-Quinto of Uppsala University and co-first author.

The Ansarve site on the island of Gotland in the Baltic Sea is embedded in an area with mostly hunter-gathers at the time. "The people buried in the Ansarve tomb are remarkably different on a genetic level compared to the contemporaneous individuals excavated from hunter-gather-contexts, showing that the burial tradition in this megalithic tomb, which lasted for over 700 years, was performed by distinct groups with roots in the European Neolithic expansion," says archaeogeneticist Magdalena Fraser of Uppsala University and co-first author.

"That we find distinct paternal lineages among the people in the megaliths, an overrepresentation of males in some tombs, and the clear kindred relationships point to towards the individuals being part of a patrilineal segment of the society rather than representing a random sample from a larger Neolithic farmer community," says Mattias Jakobsson, population-geneticist at Uppsala University and senior author of the study.

"Our study demonstrates the potential in archaeogenetics to not only reveal large-scale migrations, but also inform about Stone Age societies and the role of particular phenomena in those times such as the megalith phenomena," says Federico Sanchez-Quinto.

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NASA's Cassini reveals surprises with Titan's lakes

This near-infrared, color view from Cassini shows the sun glinting off of Titan's north polar seas.

On its final flyby of Saturn's largest moon in 2017, NASA's Cassini spacecraft gathered radar data revealing that the small liquid lakes in Titan's northern hemisphere are surprisingly deep, perched atop hills and filled with methane.

The new findings, published April 15 in Nature Astronomy, are the first confirmation of just how deep some of Titan's lakes are (more than 300 feet, or 100 meters) and of their composition. They provide new information about the way liquid methane rains on, evaporates from and seeps into Titan -- the only planetary body in our solar system other than Earth known to have stable liquid on its surface.

Scientists have known that Titan's hydrologic cycle works similarly to Earth's -- with one major difference. Instead of water evaporating from seas, forming clouds and rain, Titan does it all with methane and ethane. We tend to think of these hydrocarbons as a gas on Earth, unless they're pressurized in a tank. But Titan is so cold that they behave as liquids, like gasoline at room temperature on our planet.

Scientists have known that the much larger northern seas are filled with methane, but finding the smaller northern lakes filled mostly with methane was a surprise. Previously, Cassini data measured Ontario Lacus, the only major lake in Titan's southern hemisphere. There they found a roughly equal mix of methane and ethane. Ethane is slightly heavier than methane, with more carbon and hydrogen atoms in its makeup.

"Every time we make discoveries on Titan, Titan becomes more and more mysterious," said lead author Marco Mastrogiuseppe, Cassini radar scientist at Caltech in Pasadena, California. "But these new measurements help give an answer to a few key questions. We can actually now better understand the hydrology of Titan."

Adding to the oddities of Titan, with its Earth-like features carved by exotic materials, is the fact that the hydrology on one side of the northern hemisphere is completely different than the that of other side, said Cassini scientist and co-author Jonathan Lunine of Cornell University in Ithaca, New York.

"It is as if you looked down on the Earth's North Pole and could see that North America had completely different geologic setting for bodies of liquid than Asia does," Lunine said.

On the eastern side of Titan, there are big seas with low elevation, canyons and islands. On the western side: small lakes. And the new measurements show the lakes perched atop big hills and plateaus. The new radar measurements confirm earlier findings that the lakes are far above sea level, but they conjure a new image of landforms -- like mesas or buttes -- sticking hundreds of feet above the surrounding landscape, with deep liquid lakes on top.

The fact that these western lakes are small -- just tens of miles across -- but very deep also tells scientists something new about their geology: It's the best evidence yet that they likely formed when the surrounding bedrock of ice and solid organics chemically dissolved and collapsed. On Earth, similar water lakes are known as karstic lakes. Occurring in in areas like Germany, Croatia and the United States, they form when water dissolves limestone bedrock.

Alongside the investigation of deep lakes, a second paper in Nature Astronomy helps unravel more of the mystery of Titan's hydrologic cycle. Researchers used Cassini data to reveal what they call transient lakes. Different sets of observations -- from radar and infrared data -- seem to show liquid levels significantly changed.

The best explanation is that there was some seasonally driven change in the surface liquids, said lead author Shannon MacKenzie, planetary scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. "One possibility is that these transient features could have been shallower bodies of liquid that over the course of the season evaporated and infiltrated into the subsurface," she said.

These results and the findings from the Nature Astronomy paper on Titan's deep lakes support the idea that hydrocarbon rain feeds the lakes, which then can evaporate back into the atmosphere or drain into the subsurface, leaving reservoirs of liquid stored below.

Cassini, which arrived in the Saturn system in 2004 and ended its mission in 2017 by deliberately plunging into Saturn's atmosphere, mapped more than 620,000 square miles (1.6 million square kilometers) of liquid lakes and seas on Titan's surface. It did the work with the radar instrument, which sent out radio waves and collected a return signal (or echo) that provided information about the terrain and the liquid bodies' depth and composition, along with two imaging systems that could penetrate the moon's thick atmospheric haze.

The crucial data for the new research were gathered on Cassini's final close flyby of Titan, on April 22, 2017. It was the mission's last look at the moon's smaller lakes, and the team made the most of it. Collecting echoes from the surfaces of small lakes while Cassini zipped by Titan was a unique challenge.

"This was Cassini's last hurrah at Titan, and it really was a feat," Lunine said.

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Astronomers discover third planet in the Kepler-47 circumbinary system

This is an artistic rendition of the Kepler-47 circumbinary planet system. The three planets with the large middle planet being the newly discovered Kepler47d.

Astronomers have discovered a third planet in the Kepler-47 system, securing the system's title as the most interesting of the binary-star worlds. Using data from NASA's Kepler space telescope, a team of researchers, led by astronomers at San Diego State University, detected the new Neptune-to-Saturn-size planet orbiting between two previously known planets.

With its three planets orbiting two suns, Kepler-47 is the only known multi-planet circumbinary system. Circumbinary planets are those that orbit two stars.

The planets in the Kepler-47 system were detected via the "transit method." If the orbital plane of the planet is aligned edge-on as seen from Earth, the planet can pass in front of the host stars, leading to a measurable decrease in the observed brightness. The new planet, dubbed Kepler-47d, was not detected earlier due to weak transit signals.

As is common with circumbinary planets, the alignment of the orbital planes of the planets change with time. In this case, the middle planet's orbit has become more aligned, leading to a stronger transit signal. The transit depth went from undetectable at the beginning of the Kepler Mission to the deepest of the three planets over the span of just four years.

The SDSU researchers were surprised by both the size and location of the new planet. Kepler-47d is the largest of the three planets in the Kepler-47 system.

"We saw a hint of a third planet back in 2012, but with only one transit we needed more data to be sure," said SDSU astronomer Jerome Orosz, the paper's lead author. "With an additional transit, the planet's orbital period could be determined, and we were then able to uncover more transits that were hidden in the noise in the earlier data."

William Welsh, SDSU astronomer and the study's co-author, said he and Orosz expected any additional planets in the Kepler-47 system to be orbiting exterior to the previously known planets. "We certainly didn't expect it to be the largest planet in the system. This was almost shocking," said Welsh. Their research was recently published in the Astronomical Journal.

With the discovery of the new planet, a much better understanding of the system is possible. For example, researchers now know the planets in this circumbinary system are very low density -- less than that of Saturn, the Solar System planet with the lowest density.

While a low density is not that unusual for the sizzling hot-Jupiter type exoplanets, it is rare for mild-temperature planets. Kepler-47d's equilibrium temperature is roughly 50 o F (10 o C), while Kepler-47c is 26 o F (32 o C). The innermost planet, which is the smallest circumbinary planet known, is a much hotter 336 o F (169 o C).

The inner, middle, and outer planets are 3.1, 7.0, and 4.7 times the size of the Earth, and take 49, 87, and 303 days, respectively, to orbit around their suns. The stars themselves orbit each other in only 7.45 days; one star is similar to the Sun, while the other has a third of the mass of the Sun. The entire system is compact and would fit inside the orbit of the Earth. It is approximately 3340 light-years away in the direction of the constellation Cygnus.

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New evidence suggests volcanoes caused biggest mass extinction ever

A volcano erupts in a driving rain.

Researchers say mercury buried in ancient rock provides the strongest evidence yet that volcanoes caused the biggest mass extinction in the history of the Earth.

The extinction 252 million years ago was so dramatic and widespread that scientists call it "the Great Dying." The catastrophe killed off more than 95 percent of life on Earth over the course of hundreds of thousands of years.

Paleontologists with the University of Cincinnati and the China University of Geosciences said they found a spike in mercury in the geologic record at nearly a dozen sites around the world, which provides persuasive evidence that volcanic eruptions were to blame for this global cataclysm.

The study was published this month in the journal Nature Communications.

The eruptions ignited vast deposits of coal, releasing mercury vapor high into the atmosphere. Eventually, it rained down into the marine sediment around the planet, creating an elemental signature of a catastrophe that would herald the age of dinosaurs.

"Volcanic activities, including emissions of volcanic gases and combustion of organic matter, released abundant mercury to the surface of the Earth," said lead author Jun Shen, an associate professor at the China University of Geosciences.

The mass extinction occurred at what scientists call the Permian-Triassic Boundary. The mass extinction killed off much of the terrestrial and marine life before the rise of dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a sabre-toothed tiger and a Komodo dragon.

The eruptions occurred in a volcanic system called the Siberian Traps in what is now central Russia. Many of the eruptions occurred not in cone-shaped volcanoes but through gaping fissures in the ground. The eruptions were frequent and long-lasting and their fury spanned a period of hundreds of thousands of years.

"Typically, when you have large, explosive volcanic eruptions, a lot of mercury is released into the atmosphere," said Thomas Algeo, a professor of geology in UC's McMicken College of Arts and Sciences.

"Mercury is a relatively new indicator for researchers. It has become a hot topic for investigating volcanic influences on major events in Earth's history," Algeo said.

Researchers use the sharp fossilized teeth of lamprey-like creatures called conodonts to date the rock in which the mercury was deposited. Like most other creatures on the planet, conodonts were decimated by the catastrophe.

The eruptions propelled as much as 3 million cubic kilometers of ash high into the air over this extended period. To put that in perspective, the 1980 eruption of Mount St. Helens in Washington sent just 1 cubic kilometer of ash into the atmosphere, even though ash fell on car windshields as far away as Oklahoma.

In fact, Algeo said, the Siberian Traps eruptions spewed so much material in the air, particularly greenhouse gases, that it warmed the planet by an average of about 10 degrees centigrade.

The warming climate likely would have been one of the biggest culprits in the mass extinction, he said. But acid rain would have spoiled many bodies of water and raised the acidity of the global oceans. And the warmer water would have had more dead zones from a lack of dissolved oxygen.

"We're often left scratching our heads about what exactly was most harmful. Creatures adapted to colder environments would have been out of luck," Algeo said. "So my guess is temperature change would be the No. 1 killer. Effects would exacerbated by acidification and other toxins in the environment."

Stretching over an extended period, eruption after eruption prevented the Earth's food chain from recovering.

"It's not necessarily the intensity but the duration that matters," Algeo said. "The longer this went on, the more pressure was placed on the environment."

Likewise, the Earth was slow to recover from the disaster because the ongoing disturbances continued to wipe out biodiversity, he said.

Earth has witnessed five known mass extinctions over its 4.5 billion years.

Scientists used another elemental signature -- iridium -- to pin down the likely cause of the global mass extinction that wiped out the dinosaurs 65 million years ago. They believe an enormous meteor struck what is now Mexico.

The resulting plume of superheated earth blown into the atmosphere rained down material containing iridium that is found in the geologic record around the world.

Shen said the mercury signature provides convincing evidence that the Siberian Traps eruptions were responsible for the catastrophe. Now researchers are trying to pin down the extent of the eruptions and which environmental effects in particular were most responsible for the mass die-off, particularly for land animals and plants.

Shen said the Permian extinction could shed light on how global warming today might lead to the next mass extinction. If global warming, indeed, was responsible for the Permian die-off, what does warming portend for humans and wildlife today?

"The release of carbon into the atmosphere by human beings is similar to the situation in the Late Permian, where abundant carbon was released by the Siberian eruptions," Shen said.

Algeo said it is cause for concern.

"A majority of biologists believe we're at the cusp of another mass extinction -- the sixth big one. I share that view, too," Algeo said. "What we should learn is this will be serious business that will harm human interests so we should work to minimize the damage."

People living in marginal environments such as arid deserts will suffer first. This will lead to more climate refugees around the world.

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Abundance of information narrows our collective attention span

The negative effects of social media and a hectic news cycle on our attention span has been an on-going discussion in recent years -- but there's been a lack of empirical data supporting claims of a 'social acceleration'. A new study in Nature Communications finds that our collective attention span is indeed narrowing, and that this effect occurs -- not only on social media -- but also across diverse domains including books, web searches, movie popularity, and more.

Our public discussion can appear to be increasingly fragmented and accelerated. Sociologists, psychologists, and teachers have warned of an emerging crisis stemming from a 'fear of missing out', keeping up to date on social media, and breaking news coming at us 24/7. So far, the evidence to support these claims has only been hinted at or has been largely anecdotal. There has been an obvious lack of a strong empirical foundation.

In a new study, conducted by a team of European scientists from Technische Universität Berlin, Max Planck Institute for Human Development, University College Cork, and DTU, this empirical evidence has been presented regarding one dimension of social acceleration, namely the increasing rates of change within collective attention.

"It seems that the allocated attention in our collective minds has a certain size, but that the cultural items competing for that attention have become more densely packed. This would support the claim that it has indeed become more difficult to keep up to date on the news cycle, for example." says Professor Sune Lehmann from DTU Compute.

The scientists have studied Twitter data from 2013 to 2016, books from Google Books going back 100 years, movie ticket sales going back 40 years, and citations of scientific publications from the last 25 years. In addition, they have gathered data from Google Trends (2010-2018), Reddit (2010-2015), and Wikipedia (2012-2017).

Rapid exhaustion of attention ressources

On this background, they find empirical evidence of ever-steeper gradients and shorter bursts of collective attention given to each cultural item. The paper uses a model for this attention economy to suggest that the accelerating vicissitudes of popular content are driven by increasing production and consumption of content, and therefore are not intrinsic to social media. This results in a more rapid exhaustion of limited attention resources.

When looking into the global daily top 50 hashtags on Twitter, the scientists found that peaks became increasingly steep and frequent: In 2013 a hashtag stayed in the top 50 for an average of 17.5 hours. This gradually decreases to 11.9 hours in 2016.

This trend is mirrored when looking at other domains, online and offline -- and covering different periods. Looking, for instance, at the occurrence of the same five-word phrases (n-grams) in Google Books for the past 100 years, and the success of top box office movies. The same goes for Google searches and the number of Reddit comments on individual submissions. When looking into Wikipedia and scientific publications, however, this trend was not mirrored. Though the exact reason is unclear, the authors suggest that it could be because of their being knowledge communication systems.

"We wanted to understand which mechanisms could drive this behavior. Picturing topics as species that feed on human attention, we designed a mathematical model with three basic ingredients: 'hotness', aging and the thirst for something new." says Dr. Philipp Hövel, lecturer for applied mathematics, University College Cork.

This model offers an interpretation of their observations. When more content is produced in less time, it exhausts the collective attention earlier. The shortened peak of public interest for one topic is directly followed by the next topic, because of the fierce competition for novelty.

"The one parameter in the model that was key in replicating the empirical findings was the input rate -- the abundance of information. The world has become increasingly well connected in the past decades. This means that content is increasing in volume, which exhausts our attention and our urge for 'newness' causes us to collectively switch between topics more rapidly." says postdoc Philipp Lorenz-Spreen, Max Planck Institute for Human Development.

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The history of humanity in your face

These are skulls of hominins over the last 4.4 million years.

The face you see in the mirror is the result of millions of years of evolution and reflects the most distinctive features that we use to identify and recognize each other, molded by our need to eat, breath, see, and communicate.

But how did the modern human face evolve to look the way it does? Eight of the top experts on the evolution of the human face, including Arizona State University's William Kimbel, collaborated on an article published this week in the journal Nature Ecology & Evolution to tell this four-million-year story. Kimbel is the director of the Institute of Human Origins and Virginia M. Ullman Professor of Natural History and the Environment in the School of Human Evolution and Social Change.

After our ancestors stood on two legs and began to walk upright, at least 4.5 million years ago, the skeletal framework of a bipedal creature was pretty well formed. Limbs and digits became longer or shorter, but the functional architecture of bipedal locomotion had developed.

But the skull and teeth provide a rich library of changes that we can track over time, describing the history of evolution of our species. Prime factors in the changing structure of the face include a growing brain and adaptations to respiratory and energy demands, but most importantly, changes in the jaw, teeth, and face responded to shifts in diet and feeding behavior. We are, or we evolved to be, what we eat -- literally!

Diet has played a large role in explaining evolutionary changes in facial shape. The earliest human ancestors ate tough plant foods that required large jaw muscles and cheek teeth to break down, and their faces were correspondingly broad and deep, with massive muscle attachment areas.

As the environment changed to drier, less wooded conditions, especially in the last two million years, early Homo species began to routinely use tools to break down foods or cut meat. The jaws and teeth changed to meet a less demanding food source, and the face became more delicate, with a flatter countenance.

Changes in the human face may not be due only to purely mechanical factors. The human face, after all, plays an important role in social interaction, emotion, and communication. Some of these changes may be driven, in part, by social context. Our ancestors were challenged by the environment and increasingly impacted by culture and social factors. Over time, the ability to form diverse facial expressions likely enhanced nonverbal communication.

Large, protruding brow ridges are typical of some extinct species of our own genus, Homo, like Homo erectus and the Neanderthals. What function did these structures play in adaptive changes in the face? The African great apes also have strong brow ridges, which researchers suggest help to communicate dominance or aggression. It is probably safe to conclude that similar social functions influenced the facial form of our ancestors and extinct relatives. Along with large, sharp canine teeth, large brow ridges were lost along the evolutionary road to our own species, perhaps as we evolved to become less aggressive and more cooperative in social contexts.

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Meteoroid strikes eject precious water from moon

Artist's concept of the LADEE spacecraft (left) detecting water vapor from meteoroid impacts on the Moon (right).

Researchers from NASA and the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, report that streams of meteoroids striking the Moon infuse the thin lunar atmosphere with a short-lived water vapor.

The findings will help scientists understand the history of lunar water -- a potential resource for sustaining long term operations on the Moon and human exploration of deep space. Models had predicted that meteoroid impacts could release water from the Moon as a vapor, but scientists hadn't yet observed the phenomenon.

Now, the team has found dozens of these events in data collected by NASA's Lunar Atmosphere and Dust Environment Explorer. LADEE was a robotic mission that orbited the Moon to gather detailed information about the structure and composition of the thin lunar atmosphere, and determine whether dust is lofted into the lunar sky.

"We traced most of these events to known meteoroid streams, but the really surprising part is that we also found evidence of four meteoroid streams that were previously undiscovered," said Mehdi Benna of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland Baltimore County. Benna is the lead author of the study, published in Nature Geosciences.

The newly identified meteoroid streams, observed by LADEE, occurred on January 9, April 2, April 5 and April 9, 2014.

There's evidence that the Moon has water (H2O) and hydroxyl (OH), a more reactive relative of H2O. But debates continue about the origins of the water, whether it is widely distributed and how much might be present.

"The Moon doesn't have significant amounts of H2O or OH in its atmosphere most of the time," said Richard Elphic, the LADEE project scientist at NASA's Ames Research Center in California's Silicon Valley. "But when the Moon passed through one of these meteoroid streams, enough vapor was ejected for us to detect it. And then, when the event was over, the H2O or OH went away."

Lunar scientists often use the term "water" to refer to both H2O and OH. Figuring out how much H2O and how much OH are present is something future Moon missions might address.

LADEE, which was built and managed by NASA's Ames Research Center in California's Silicon Valley, detected the vapor using its Neutral Mass Spectrometer, an instrument built by Goddard. The mission orbited the Moon from October 2013 to April 2014 and gathered detailed information about the structure and composition of the lunar atmosphere, or more correctly, the "exosphere" -- a faint envelope of gases around the Moon.

To release water, the meteoroids had to penetrate at least 3 inches (8 centimeters) below the surface. Underneath this bone-dry top layer lies a thin transition layer, then a hydrated layer, where water molecules likely stick to bits of soil and rock, called regolith.

From the measurements of water in the exosphere, the researchers calculated that the hydrated layer has a water concentration of about 200 to 500 parts per million, or about 0.02 to 0.05 percent by weight. This concentration is much drier than the driest terrestrial soil, and is consistent with earlier studies. It is so dry that one would need to process more than a metric ton of regolith in order to collect 16 ounces of water.

Because the material on the lunar surface is fluffy, even a meteoroid that's a fraction of an inch (5 millimeters) across can penetrate far enough to release a puff of vapor. With each impact, a small shock wave fans out and ejects water from the surrounding area.

When a stream of meteoroids rains down on the lunar surface, the liberated water will enter the exosphere and spread through it. About two-thirds of that vapor escapes into space, but about one-third lands back on the surface of the Moon.

These findings could help explain the deposits of ice in cold traps in the dark reaches of craters near the poles. Most of the known water on the Moon is located in cold traps, where temperatures are so low that water vapor and other volatiles that encounter the surface will remain stable for a very long time, perhaps up to several billion years. Meteoroid strikes can transport water both into and out of cold traps.

The team ruled out the possibility that all of the water detected came from the meteoroids themselves.

"We know that some of the water must be coming from the Moon, because the mass of water being released is greater than the water mass within the meteoroids coming in," said the second author of the paper, Dana Hurley of the Johns Hopkins University Applied Physics Laboratory.

The analysis indicates that meteoroid impacts release water faster than it can be produced from reactions that occur when the solar wind hits the lunar surface.

"The water being lost is likely ancient, either dating back to the formation of the Moon or deposited early in its history," said Benna.

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Scientists print first 3D heart using patient's biological materials

A 3D-printed, small-scaled human heart engineered from the patient's own materials and cells.

In a major medical breakthrough, Tel Aviv University researchers have "printed" the world's first 3D vascularised engineered heart using a patient's own cells and biological materials. Their findings were published on April 15 in a study in Advanced Science.

Until now, scientists in regenerative medicine -- a field positioned at the crossroads of biology and technology -- have been successful in printing only simple tissues without blood vessels.

"This is the first time anyone anywhere has successfully engineered and printed an entire heart replete with cells, blood vessels, ventricles and chambers," says Prof. Tal Dvir of TAU's School of Molecular Cell Biology and Biotechnology, Department of Materials Science and Engineering, Center for Nanoscience and Nanotechnology and Sagol Center for Regenerative Biotechnology, who led the research for the study.

Heart disease is the leading cause of death among both men and women in the United States. Heart transplantation is currently the only treatment available to patients with end-stage heart failure. Given the dire shortage of heart donors, the need to develop new approaches to regenerate the diseased heart is urgent.

"This heart is made from human cells and patient-specific biological materials. In our process these materials serve as the bioinks, substances made of sugars and proteins that can be used for 3D printing of complex tissue models," Prof. Dvir says. "People have managed to 3D-print the structure of a heart in the past, but not with cells or with blood vessels. Our results demonstrate the potential of our approach for engineering personalized tissue and organ replacement in the future."

Research for the study was conducted jointly by Prof. Dvir, Dr. Assaf Shapira of TAU's Faculty of Life Sciences and Nadav Moor, a doctoral student in Prof. Dvir's lab.

"At this stage, our 3D heart is small, the size of a rabbit's heart," explains Prof. Dvir. "But larger human hearts require the same technology."

For the research, a biopsy of fatty tissue was taken from patients. The cellular and a-cellular materials of the tissue were then separated. While the cells were reprogrammed to become pluripotent stem cells, the extracellular matrix (ECM), a three-dimensional network of extracellular macromolecules such as collagen and glycoproteins, were processed into a personalized hydrogel that served as the printing "ink."

After being mixed with the hydrogel, the cells were efficiently differentiated to cardiac or endothelial cells to create patient-specific, immune-compatible cardiac patches with blood vessels and, subsequently, an entire heart.

According to Prof. Dvir, the use of "native" patient-specific materials is crucial to successfully engineering tissues and organs.

"The biocompatibility of engineered materials is crucial to eliminating the risk of implant rejection, which jeopardizes the success of such treatments," Prof. Dvir says. "Ideally, the biomaterial should possess the same biochemical, mechanical and topographical properties of the patient's own tissues. Here, we can report a simple approach to 3D-printed thick, vascularized and perfusable cardiac tissues that completely match the immunological, cellular, biochemical and anatomical properties of the patient."

The researchers are now planning on culturing the printed hearts in the lab and "teaching them to behave" like hearts, Prof. Dvir says. They then plan to transplant the 3D-printed heart in animal models.

"We need to develop the printed heart further," he concludes. "The cells need to form a pumping ability; they can currently contract, but we need them to work together. Our hope is that we will succeed and prove our method's efficacy and usefulness.

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Interplay of pollinators and pests influences plant evolution

Brassica rapa pollinated by bumblebees has more attractive flowers.

Brassica rapa plants pollinated by bumblebees evolve more attractive flowers. But this evolution is compromised if caterpillars attack the plant at the same time. With the bees pollinating them less effectively, the plants increasingly self-pollinate. In a greenhouse evolution experiment, scientists at the University of Zurich have shown just how much the effects of pollinators and pests influence each other.

In nature, plants interact with a whole range of organisms, driving the evolution of their specific characteristics. While pollinators influence floral traits and reproduction, herbivorous insects enhance the plant's defense mechanisms. Now botanists at the University of Zurich have investigated the way these different interactions influence each other, and how rapidly plants adapt when the combination of selective agents with which they interact changes.

Experimental evolution in real time

In a two-year greenhouse experiment, Florian Schiestl, professor at UZH's Department of Systematic and Evolutionary Botany, and doctoral candidate Sergio Ramos have demonstrated a powerful interplay between the effects of pollinating insects and those of herbivores. For their experiment they used Brassica rapa, a plant closely related to oilseed rape, interacting with bumblebees and caterpillars as selective agents. Over six generations they subjected four groups of plants to different treatments: with bee pollination only, bee pollination with herbivory (caterpillars), hand pollination without herbivory, and hand pollination with herbivory.

Balance between attraction and defense

After this experimental evolution study, the plants pollinated by bumblebees without herbivory were most attractive to the pollinators: they evolved more fragrant flowers, which tended to be larger. "These plants had adapted to the bees' preferences during the experiment," explains Sergio Ramos. By contrast, bee-pollinated plants with herbivory were less attractive, with higher concentrations of defensive toxic metabolites and less fragrant flowers that tended to be smaller. "The caterpillars compromise the evolution of attractive flowers, as plants assign more resources to defense," says Ramos.

Combined impact on reproduction

The powerful interplay between the effects of bees and caterpillars was also evident in the plants' reproductive characteristics: In the course of their evolution, for example, the bee-pollinated plants developed a tendency to spontaneously self-pollinate when they were simultaneously damaged by caterpillars. Plants attacked by caterpillars developed less attractive flowers, which affected the behavior of the bees so that they pollinated these flowers less well.

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Conservationists discover hidden diversity in ancient frog family

Metamorph Sooglossus sechellensis balanced on a 10 pence coin.

Research scientists led by the University of Kent have uncovered hidden diversity within a type of frog found only in the Seychelles, showing that those on each island have their own distinct lineage.

The family tree of sooglossid frogs dates back at least 63 million years. They are living ancestors of those frogs that survived the meteor strike on earth approximately 66 million years ago, and their most recent common ancestor dates back some 63 million years, making them a highly evolutionarily distinct group.

However, recent work on their genetics led by Dr Jim Labisko from Kent's School of Anthropology and Conversation revealed that until they can complete further investigations into their evolutionary relationships and verify the degree of differentiation between each island population, each island lineage needs to be considered as a potential new species, known as an Evolutionarily Significant Unit (ESU). As a result, Dr Labisko advises conservation managers they should do likewise and consider each as an ESU.

There are just four species of sooglossid frog; the Seychelles frog (Sooglossus sechellensis), Thomasset's rock frog (So. thomasseti), Gardiner's Seychelles frog (Sechellophryne gardineri) and the Seychelles palm frog (Se. pipilodryas).

Of the currently recognised sooglossid species, two (So. thomasseti and Se. pipilodryas) have been assessed as Critically Endangered, and two (So. sechellensis and Se. gardineri) as Endangered for the International Union for Conservation of Nature IUCN Red List. All four species are in the top 50 of ZSL's (Zoological Society of London) Evolutionarily Distinct Globally Endangered (EDGE) amphibians.

Given the Red List and EDGE status of these unique frogs Dr Labisko and his colleagues are carrying out intensive monitoring to assess the level of risk from both climate change and disease to the endemic amphibians of the Seychelles.

Dr Labisko, who completed his PhD on sooglossid frogs at Kent's Durrell Institute of Conservation and Ecology in 2016 said many of these frogs are so small and good at hiding the only way to observe them is by listening for their calls. Although tiny, the sound they emit can be around 100 decibels, equivalent to the sound volume of a power lawnmower'.

Dr Labisko's team are using sound monitors to record the vocal activity of sooglossid frogs for five minutes every hour, every day of the year, in combination with dataloggers that are sampling temperature and moisture conditions on an hourly basis

Dr Labisko said: 'Amphibians play a vital role in the ecosystem as predators, munching on invertebrates like mites and mosquitos, so they contribute to keeping diseases like malaria and dengue in check. Losing them will have serious implications for human health.'

As a result of this study into the frogs, the research team will also contribute to regional investigations into climate change, making a local impact in the Seychelles.

Amphibians around the world are threatened by a lethal fungus known as chytrid. The monitoring of these sooglossid frogs will provide crucial data on amphibian behaviour in relation to climate and disease. If frogs are suddenly not heard in an area where they were previously, this could indicate a range-shift in response to warming temperatures, or the arrival of disease such as chytrid -- the Seychelles is one of only two global regions of amphibian diversity where the disease is yet to be detected.

It may also impact on a variety of other endemic Seychelles flora and fauna, including the caecilians, a legless burrowing amphibian that is even more difficult to study than the elusive sooglossids.

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