Could acid-neutralizing life-forms make habitable pockets in Venus’ clouds?

It's hard to imagine a more inhospitable world than our closest planetary neighbor. With an atmosphere thick with carbon dioxide, and a surface hot enough to melt lead, Venus is a scorched and suffocating wasteland where life as we know it could not survive. The planet's clouds are similarly hostile, blanketing the planet in droplets of sulfuric acid caustic enough to burn a hole through human skin.

And yet, a new study supports the longstanding idea that if life exists, it might make a home in Venus' clouds. The study's authors, from MIT, Cardiff University, and Cambridge University, have identified a chemical pathway by which life could neutralize Venus' acidic environment, creating a self-sustaining, habitable pocket in the clouds.

Within Venus' atmosphere, scientists have long observed puzzling anomalies -- chemical signatures that are hard to explain, such as small concentrations of oxygen and nonspherical particles unlike sulfuric acid's round droplets. Perhaps most puzzling is the presence of ammonia, a gas that was tentatively detected in the 1970s, and that by all accounts should not be produced through any chemical process known on Venus.

In their new study, the researchers modeled a set of chemical processes to show that if ammonia is indeed present, the gas would set off a cascade of chemical reactions that would neutralize surrounding droplets of sulfuric acid and could also explain most of the anomalies observed in Venus' clouds. As for the source of ammonia itself, the authors propose that the most plausible explanation is of biological origin, rather than a nonbiological source such as lightning or volcanic eruptions.

As they write in their study, the chemistry suggests that "life could be making its own environment on Venus."

This tantalizing new hypothesis is testable, and the researchers provide a list of chemical signatures for future missions to measure in Venus' clouds, to either confirm or contradict their idea.

"No life that we know of could survive in the Venus droplets," says study co-author Sara Seager, the Class of 1941 Professor of Planetary Sciences in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "But the point is, maybe some life is there, and is modifying its environment so that it is livable."

The study's co-authors include Janusz Petkowski, William Bains, and Paul Rimmer, who are affiliated with MIT, Cardiff University, and Cambridge University.

Life suspect

"Life on Venus" was a trending phrase last year, when scientists including Seager and her co-authors reported the detection of phosphine in the planet's clouds. On Earth, phosphine is a gas that is produced mainly through biological interactions. The discovery of phosphine on Venus leaves room for the possibility of life. Since then, however, the discovery has been widely contested.

"The phosphine detection ended up becoming incredibly controversial," Seager says. "But phosphine was like a gateway, and there's been this resurgence in people studying Venus."

Inspired to look more closely, Rimmer began combing through data from past missions to Venus. In these data, he identified anomalies, or chemical signatures, in the clouds that had gone unexplained for decades. In addition to the presence of oxygen and nonspherical particles, anomalies included unexpected levels of water vapor and sulfur dioxide.

Rimmer proposed the anomalies might be explained by dust. He argued that minerals, swept up from Venus' surface and into the clouds, could interact with sulfuric acid to produce some, though not all, of the observed anomalies. He showed the chemistry checked out, but the physical requirements were unfeasible: A massive amount of dust would have to loft into the clouds to produce the observed anomalies.

Seager and her colleagues wondered if the anomalies could be explained by ammonia. In the 1970s, the gas was tentatively detected in the planet's clouds by the Venera 8 and Pioneer Venus probes. The presence of ammonia, or NH3, was an unsolved mystery.

"Ammonia shouldn't be on Venus," Seager says. "It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."

Livable clouds

If the team were to assume that life was the source of ammonia, could this explain the other anomalies in Venus' clouds? The researchers modeled a series of chemical processes in search of an answer.

They found that if life were producing ammonia in the most efficient way possible, the associated chemical reactions would naturally yield oxygen. Once present in the clouds, ammonia would dissolve in droplets of sulfuric acid, effectively neutralizing the acid to make the droplets relatively habitable. The introduction of ammonia into the droplets would transform their formerly round, liquid shape into more of a nonspherical, salt-like slurry. Once ammonia dissolved in sulfuric acid, the reaction would trigger any surrounding sulfur dioxide to dissolve as well.

The presence of ammonia then could indeed explain most of the major anomalies seen in Venus' clouds. The researchers also show that sources such as lightning, volcanic eruptions, and even a meteorite strike could not chemically produce the amount of ammonia required to explain the anomalies. Life, however, might.

In fact, the team notes that there are life-forms on Earth -- particuarly in our own stomachs -- that produce ammonia to neutralize and make livable an otherwise highly acidic environment.

"There are very acidic environments on Earth where life does live, but it's nothing like the environment on Venus -- unless life is neutralizing some of those droplets," Seager says.

Scientists may have a chance to check for the presence of ammonia, and signs of life, in the next several years with the Venus Life Finder Missions, a set of proposed privately funded missions, of which Seager is principal investigator, that plan to send spacecraft to Venus to measure its clouds for ammonia and other signatures of life.

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Plants as cold specialists from the ice age

As cold relics in an increasingly warming world, plants of the spoonweed group time and again quickly adapted to a changing climate during the Ice Ages of the last two million years. An international team of evolutionary biologists and botanists led by Prof. Dr Marcus Koch of Heidelberg University used genomic analyses to study what factors favour adaptation to extreme climatic conditions. The evolutionary history of the Brassicaceae family provides insights into how plants may be able to cope with climate change in the future.

"With the challenges of increasing global warming, developing a basic understanding of how plants adapted to severe environmental change is increasingly urgent," stresses Prof. Koch, whose "Biodiversity and Plant Systematics" working group conducts research at the Centre for Organismal Studies (COS). In many cases, their evolutionary past also strongly determines the future adaptability of plants as well as their ability to develop into new forms and types, he continues. The spoonweed genus, or Latin Cochlearia, from the Brassicaceae family separated from its Mediterranean relatives more than ten million years ago. While their direct descendants specialised in response to drought stress, the spoonweeds conquered the cold and arctic habitats at the beginning of the Ice Age 2.5 million years ago.

In controlled lab experiments, the researchers studied cultivated species from both groups to determine how they repeatedly adapted during the relatively rapidly alternating cold and warm periods over the last two million years. A "cold training" indicates that the physiological adaptations to drought and salt stress during their early evolution later helped the plants develop a high tolerance to cold. Although the researchers expected that both groups would show a pronounced response to this "cold training," there appeared to be no significant difference in response to cold stress between the cold specialists of the Arctic and Alpine regions and the dry specialists or species adapted to salt water from the Mediterranean.

Furthermore, the newly emerged plants adapted to cold developed separate gene pools that frequently came into contact with one another in the cold regions. Because spoonweeds have hardly any genetic barriers to contact between species, populations with multiple sets of chromosomes developed that, subsequently, were continually reduced in their size. "Time after time, these species were then able to occupy cold ecological niches," explains Marcus Koch.

While the gene pool of the cold specialists from the Arctic expanded, the European spoonweed population has shrunk since the last Ice Age. Cold habitats in Europe are disappearing in the face of significant global warming, thus seriously endangering all spoonweed species. Only the Danish spoonweed, with its abundant sets of chromosomes, remains unscathed and in some cases is even spreading. "It is the only species of spoonweed that changed its life cycle and flourishes in salt and sand locations. In some of its ecological features, it resembles its faraway Mediterranean cousins," adds Prof. Koch. For the researchers, the physiological adaptability of the spoonweeds makes them a promising model system to simultaneously study adaptations to drought, cold, and salt stress.

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Extinct reptile discovery reveals earliest origins of human teeth, study finds

A new extinct reptile species has shed light on how our earliest ancestors became top predators by modifying their teeth in response to environmental instability around 300 million years ago.

In findings published in Royal Society Open Science, researchers at the University of Bristol have discovered that this evolutionary adaptation laid the foundations for the incisor, canine and molar teeth that all mammals -- including humans -- possess today.

Shashajaia is one of the most primitive members of a group called the Sphenacodontoidea, which includes the famous sail-backed Dimetrodon, and mammal-like reptiles known as therapsids, which eventually evolved into mammals. It is remarkable for its age and anatomy, possessing a very unique set of teeth that set it apart from other synapsids -- meaning the animal lineage that mammals belong to -- of the time.

Dr Suresh Singh of the School of Earth Sciences explained: "The teeth show clear differentiation in shape between the front and back of the jaw, organised into distinct regions. This is the basic precursor of what mammals have today -- incisors and canines up front, with molars in the back. This is the oldest record of such teeth in our evolutionary tree."

The novel dentition of Shashajaia demonstratesthat large, canine-like differentiated teeth were present in synapsids by the Late Carboniferous period -- a time famous for giant insects and the global swampy rainforests that produced much of our coal deposits.

By analytically comparing the tooth variation observed in Shashajaia with other synapsids, the study suggests that distinctive, specialised teeth likely emerged in our synapsid ancestors as a predatory adaptation to help them catch prey at a time when global climate change approximately 300 million years ago saw once-prevalent Carboniferous wetlands replaced by more arid, seasonal environments. These new, more changeable conditions brought a change in the availability and diversity of prey.

Lead author Dr Adam Huttenlocker of the University of Southern California said: "Canine-like teeth in small sphenacodonts like Shashajaia might have facilitated a fast, raptorial bite in riparian habitats where a mix of terrestrial and semi-aquatic prey could be found in abundance."

The new reptile is one of the oldest synapsids. It was named "Shashajaia bermani," which translates as Berman's bear heart, to honour the 51-year career of veteran palaeontologist, Dr David Berman of the Carnegie Museum of Natural History, as well as the local Navajo people of the discovery site within the Bears Ears National Monument, Utah.

Dr Singh said: "The study is a testament to Dr Berman who originally discovered the fossil site in 1989, and his decades of work on synapsids and other early tetrapods from the Bears Ears region of Utah which helped to justify the Bears Ears National Monument in 2016."

The site is located within an area known as the Valley of the Gods and is of huge importance to palaeontologists.

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New muscle layer discovered on the jaw

Human anatomy still has a few surprises in store for us: researchers at the University of Basel have discovered a previously overlooked section of our jaw muscles and described this layer in detail for the first time.

The masseter muscle is the most prominent of the jaw muscles. If you place your fingers on the back of your cheeks and press your teeth together, you'll feel the muscle tighten. Anatomy textbooks generally describe the masseter as consisting of one superficial and one deep part.

Now, researchers led by Dr. Szilvia Mezey from the Department of Biomedicine at the University of Basel and Professor Jens Christoph Türp from the University Center for Dental Medicine Basel (UZB) have described the structure of the masseter muscle as consisting of an additional third, even deeper layer. In the scientific journal Annals of Anatomy, they propose that this layer be given the name Musculus masseter pars coronidea -- in other words, the coronoid section of the masseter -- because the newly described layer of muscle is attached to the muscular (or "coronoid") process of the lower jaw.

The anatomical study was based on detailed examination of formalin-fixed jaw musculature, computer tomographic scans and the analysis of stained tissue sections from deceased individuals who had donated their bodies to science. This was in addition to MRI data from a living person.

As if a new animal species had been discovered

"This deep section of the masseter muscle is clearly distinguishable from the two other layers in terms of its course and function," explains Mezey. The arrangement of the muscle fibers, she says, suggests that this layer is involved in the stabilization of the lower jaw. It also appears to be the only part of the masseter that can pull the lower jaw backwards -- that is, toward the ear.

A look at historical anatomy studies and textbooks reveals that the structure of the masseter muscle has already raised questions in the past. In a previous edition of Gray's Anatomy, from the year 1995, the editors also describe the masseter muscle as having three layers, although the cited studies were based on the jaw musculature of other species and partly contradicted one another.

Other individual studies from the early 2000s also reported three layers, but they divided the superficial section of the masseter into two layers and agreed with standard works in their description of the deeper section.

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Sauropod dinosaurs were restricted to warmer regions of Earth

Giant, long-necked sauropods, thought to include the largest land animals ever to have existed, preferred to live in warmer, more tropical regions on Earth, suggesting they may have had a different physiology from other dinosaurs, according to a new study led by researchers at UCL and the University of Vigo.

The study, published in the journal Current Biology, investigated the enigma of why sauropod fossils are only found at lower latitudes, while fossils of other main dinosaur types seem ubiquitously present, with many located in the polar regions.

The researchers analysed the fossil record across the Mesozoic era (the time of the dinosaurs), lasting from around 230 to 66 million years ago, looking at occurrences of fossils of the three main dinosaur types: sauropods, which include the Brontosaurus and the Diplodocus, theropods ("lizard-hipped"), which include velociraptors and Tyrannosaurus rex, and ornithischians ("bird-hipped") such as the Triceratops.

Combining this fossil data with data about climate throughout the period, along with information about how continents have moved across the globe, the researchers concluded that sauropods were restricted to warmer, drier habitats than other dinosaurs. These habitats were likely to be open, semi-arid landscapes, similar to today's savannahs.

Co-author Dr Philip Mannion (UCL Earth Sciences) said: "Our research shows that some parts of the planet always seemed to be too cold for sauropods. They seem to have avoided any temperatures approaching freezing. Other dinosaur types, in contrast, could thrive in Earth's polar regions, from innermost Antarctica to polar Alaska -- which, due to the warmer climate, were ice-free, with lush vegetation.

"This suggests sauropods had different thermal requirements from other dinosaurs, relying more on their external environment to heat their bodies -- slightly closer to being 'cold-blooded', like modern-day reptiles. Their grand size hints that this physiology may have been unique."

First author Dr Alfio Alessandro Chiarenza, formerly of UCL who is now based at the University of Vigo, Spain, said: "It may be that sauropods were physiologically incapable of thriving in colder regions, or that they thrived less well in these areas than their dinosaurian cousins and were outcompeted.

"A mix of features may have helped sauropods shed heat more easily than mammals do today. Their long necks and tails would have given them a larger surface area, and they may have had a respiratory system more akin to birds, which is much more efficient.

"Some species of theropods and ornithischians are known to have had feathers or downy fur helping them retain body warmth. This suggests they may have generated their own body heat. For sauropods, however, there is no evidence of this kind of insulation.

"Sauropods' strategies for keeping their eggs warm may also have differed from the other dinosaurs. Theropods probably warmed eggs by sitting on them, whereas ornithischians seem to have used heat generated by decaying plants. Sauropods, meanwhile, may have buried their eggs, relying on heat from the sun and the ground."

In their paper, the researchers noted that the fossil record showed zero occurrences of sauropods above a latitude of 50 degrees north -- an area encompassing most of Canada, Russia, northern Europe and the UK -- or below 65 degrees south, encompassing Antarctica. In contrast, there are rich records for theropods and ornithischians living above 50 degrees north in later periods (from 145 million years ago).

To test if this was a true reflection of where sauropods lived, researchers used a statistical technique to adjust for gaps in the fossil record, and also analysed where the highest diversities of dinosaur types were in different periods throughout the Mesozoic era.

They combined fossil data with climate data, allowing an estimate of the temperature ranges of the dinosaur types' habitats, finding that sauropods' range across the latitudes was more restricted during colder periods.

They then used habitat modelling to infer which regions of the globe would likely be suitable for sauropods and the other dinosaur types to live.

While in the past it was believed that dinosaurs were ectothermic ("cold-blooded"), like reptiles today, relying on the external environment to heat their bodies, it is now thought they were closer to "warm-blooded" mammals, generating some of their own body heat (endothermic).

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Discovering sources of Roman silver coinage from the Iberian Peninsula

Despite its prior status as a luxury commodity, silver became widely used for coinage in the Roman world from the 7th century BCE onward and provided a standardized monetary system for ancient Mediterranean civilizations. However, the sources of silver used to produce Roman coinage have largely been used up, making it difficult to determine which deposits Roman miners exploited.

A new study published in the journal Geology yesterday evaluated silver sources from different mining provinces in the Iberian Peninsula to determine which locations may have been mined for silver to produce Roman coinage.

"The control of silver sources was a major geopolitical issue, and the identification of Roman silver sources may help archaeologists to reconstruct ancient fluxes of precious metals and to answer important historical questions," said Jean Milot, the lead author of this study.

The Iberian Peninsula, which includes modern Spain and Portugal, is host to world-class silver deposits, especially in the southern region. These deposits contain galena, which is the main ore of lead and an important source of silver. To extract silver, the galena ore is smelted and purified, with refined silver for coin minting able to reach a purity of over 95%.

To track the source of Roman silver, the team of researchers analyzed the silver and lead compositions of galena samples from ore deposits across the Iberian Peninsula and compared the results to the chemical signatures of silver Roman coins.

They identified two different types of galena deposits based on the silver elemental composition of the samples: silver-rich galena that would have been a likely source for Roman coinage, and silver-poor galena that would have been exploited for lead only and would have been of lower economic importance.

However, few of the ore samples had a composition that fit the silver elemental composition of the Roman silver coins. Silver-bearing ores spanned a wide range in compositional variability, but Roman coins notably have a very narrow elemental composition range.

Based on the lead elemental signatures of the galena samples, the ore deposits from southeastern Spain best fit the composition of Roman coins, suggesting that these deposits were a major source of Roman silver. Both silver-rich and silver-poor galena deposits were likely exploited here, with the extracted lead from silver-poor galena able to be mixed with other ores to extract silver.

These results based on chemical analyses are also consistent with archaeological evidence for ancient mining exploitation in the region.

This combined analytical toolkit provides a way to distinguish between silver-rich deposits and deposits barren of silver ore, which is critical in understanding the dynamics of silver supply in Roman times.

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After thousands of years, an iconic whale confronts a new enemy

For millennia, vast expanses of the Arctic Ocean have been untouched by humans, ocean where narwhals and other marine mammals lived undisturbed. Now that climate change is causing sea ice to melt, there has been an uptick of human activity in the Arctic. This has resulted in significantly more noise from an array of human sources, including seismic surveys, mine blasts, port projects and cruise ships.

Although the noise is not violently loud when it comes a from a fair distance, for narwhals, the noise is disturbing and triggers stress -- even many kilometers away. These are the results of unique experiments conducted with the iconic whale. The University of Copenhagen has helped the Greenland Institute of Natural Resources (Pinngortitaleriffik) to analyse the data collected during the research.

Narwhals are notoriously difficult to study because they only live in the hard-to-reach High Arctic, which is often covered by ice. But the research team managed to tag a herd of narwhals in the Scoresby Sound fjord system of East Greenland using a variety of measurement equipment. They then positioned a ship in the fjord, which exposed the animals to noise -- both from the ship's engine and from a seismic airgun used for oil exploration.

"The narwhals' reactions indicate that they are frightened and stressed. They stop emitting the click sounds that they need to feed, they stop diving deep and they swim close to shore, a behaviour that they usually only display when feeling threatened by killer whales. This behavior means that they have no chance of finding food for as long as the noise persists," explains marine biologist Outi Tervo of the Greenland Institute of Natural Resources, who is one of the researchers behind the study.

Researchers can also see that the whales make an uncommon number of strokes with their tails when fleeing from a vessel. This may pose a danger to them because it vastly depletes their energy reserves. Constant energy conservation is important for narwhals as they need a great deal of oxygen to dive several hundred meters below the surface for food and return to the surface for air.

Everything in a narwhal's life is sound

Narwhals spend much of their time in the dark -- partly because the Arctic is dark for half of the year, and partly because these unicorns of the sea hunt at depths of up to 1800 meters, where there is no light. Thus, everything in a narwhal's life is based on sound. And like bats, they orient themselves by echolocation -- which includes emitting click sounds as they hunt.

"Our data shows that narwhals react to noise 20-30 kilometers away from a noise source by completely stopping their clicking sounds. And in one case, we could measure this from a source 40 kilometers away. It is quite surprising that we can measure how something so far away can influence whale behaviour," says Professor Susanne Ditlevsen of the University of Copenhagen's Department of Mathematical Sciences.

Professor Ditlevsen was responsible for the statistical analyses of the enormous and extremely complicated data sets that emerged from the experiments, where data was collected via underwater microphone, GPS, accelerometer (an apparatus that measures movement in three directions) and heart rate monitors. She continues:

"Even when a ship's noise is lower than the background noise in the ocean and we can no longer hear it with our advanced equipment, the whales can hear and distinguish it from other sounds in their midst. And so, to a degree, their behavior is clearly affected. This demonstrates how incredibly sensitive narwhals are."

Following a week of sonic tests, the researchers observed the whales' behavior return to normal again.

"But if they are exposed to noise for a long period of time -- for example, if a port is built nearby that leads to regular shipping traffic, the whales' success in hunting could be affected for a longer period of time, which could become quite serious for them. In this case, we fear that it could have physiological consequences for them and impair their fitness," says Outi Tervo.

Calling upon to authorities

The researchers' hope is that the authorities and other decision-makers will ensure for better management of the activities that create noise pollution in narwhal habitats.

"For the most part, narwhals live around Greenland, Canada and Svalbard in Norway. As such, these countries have the main responsibility for looking after them. Because narwhals are so well-adapted to the Arctic environment, they can't just choose to go to the Caribbean instead. It is being pressured both by warmer water temperatures and in some places, by fish catch. Now, noise enters the equation," says Susanne Ditlevsen.

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California spotted owls benefit from forest restoration

This finding is showcased in "Forest restoration limits megafires and supports species conservation under climate change," a new research publication released this week in Frontiers in Ecology and the Environment. Lead author Gavin Jones, Ph.D., a research ecologist with the USDA Forest Service (USFS) Rocky Mountain Research Station, said the research shows that forest restoration and the preservation of the spotted owl are not mutually exclusive, as had previously been feared.

"We've shown that restoration provides co-benefits to owls by reducing their exposure to stand-replacing wildfire, which leads to loss of nesting habitat," Jones said.

The research team also included collaborators from the USFS Pacific Southwest Research Station, USFS Region 5, University of Wisconsin-Madison, and University of California-Merced.

The scientists developed a fire simulation model that predicted future severe fire across the Sierra Nevada through mid-century. The predicted amount of severe fire then changed as a function of simulated fuels reduction and forest restoration treatments. The fire model was then linked to a Sierra Nevada-wide population model of California spotted owls, which also responded to potential direct effects of treatments on owl habitat.

The science found that placing treatments inside owl territories cut the amount of predicted severe fire nearly in half compared to treating the same total area outside of such territories. Thus, treating inside owl territories may have an outsized effect on reducing future severe fire, while providing a net benefit to the California spotted owl population.

According to Jones, "Even under climate change, forest management can move the needle on forest ecosystem conservation by reducing future stand-replacing fire and do so in a way that safeguards habitat for sensitive species like the California spotted owl."

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Secret embraces of stars revealed by Alma

Unlike our Sun, most stars live with a companion. Sometimes, two come so close that one engulfs the other -- with far-reaching consequences. When a team of astronomers led by Chalmers University of Technology, Sweden, used the telescope Alma to study 15 unusual stars, they were surprised to find that they all recently underwent this phase. The discovery promises new insight on the sky's most dramatic phenomena -- and on life, death and rebirth among the stars.

Using the gigantic telescope Alma in Chile, a team of scientists led by Chalmers University of Technology studied 15 unusual stars in our galaxy, the Milky Way, the closest 5000 light years from Earth. Their measurements show that all the stars are double, and all have recently experienced a rare phase that is poorly understood, but is believed to lead to many other astronomical phenomena. Their results are published this week in the scientific journal Nature Astronomy.

By directing the antennas of Alma towards each star and measuring light from different molecules close to each star, the researchers hoped to find clues to their backstories. Nicknamed "water fountains," these stars were known to astronomers because of intense light from water molecules -- produced by unusually dense and fast-moving gas.

Located 5000 m above sea level in Chile, the Alma telescope is sensitive to light with wavelengths around one millimetre, invisible to human eyes, but ideal for looking through the Milky Way's layers of dusty interstellar clouds towards dust-enshrouded stars.

"We were extra curious about these stars because they seem to be blowing out quantities of dust and gas into space, some in the form of jets with speeds up to 1.8 million kilometres per hour. We thought we might find out clues to how the jets were being created, but instead we found much more than that," says Theo Khouri, first author of the new study.

Stars losing up to half their total mass

The scientists used the telescope to measure signatures of carbon monoxide molecules, CO, in the light from the stars, and compared signals from different atoms (isotopes) of carbon and oxygen. Unlike its sister molecule carbon dioxide, CO2, carbon monoxide is relatively easy to discover in space, and is a favourite tool for astronomers.

"Thanks to Alma's exquisite sensitivity, we were able to detect the very faint signals from several different molecules in the gas ejected by these stars. When we looked closely at the data, we saw details that we really weren't expecting to see," says Theo Khouri.

The observations confirmed that the stars were all blowing off their outer layers. But the proportions of the different oxygen atoms in the molecules indicated that the stars were in another respect not as extreme as they had seemed, explains team member Wouter Vlemmings, astronomer at Chalmers University of Technology.

"We realised that these stars started their lives with the same mass as the Sun, or only a few times more. Now our measurements showed that they have ejected up to 50% of their total mass, just in the last few hundred years. Something really dramatic must have happened to them," he says.

A short but intimate phase

Why were such small stars come losing so much mass so quickly? The evidence all pointed to one explanation, the scientists concluded. These were all double stars, and they had all just been through a phase in which the two stars shared the same atmosphere -- one star entirely embraced by the other.

"In this phase, the two stars orbit together in a sort of cocoon. This phase, which we call a "common envelope" phase, is really brief, and only lasts a few hundred years. In astronomical terms, it's over in the blink of an eye," says team member Daniel Tafoya of Chalmers University of Technology.

Most stars in binary systems simply orbit around a common centre of mass. These stars, however, share the same atmosphere. It can be a life-changing experience for a star, and may even lead to the stars merging completely.

Scientists believe that this sort of intimate episode can lead to some of the sky's most spectacular phenomena. Understanding how it happens could help answer some of astronomers' biggest questions about how stars live and die, Theo Khouri explains.

"What happens to cause a supernova explosion? How do black holes get close enough to collide? What's makes the beautiful and symmetric objects we call planetary nebulae? Astronomers have suspected for many years that common envelopes are part of the answers to questions like these. Now we have a new way of studying this momentous but mysterious phase," he says.

Understanding the common envelope phase will also help scientists study what will happen in the very distant future, when the Sun too will become a bigger, cooler star -- a red giant -- and engulf the innermost planets.

"Our research will help us understand how that might happen, but it gives me another, more hopeful perspective. When these stars embrace, they send dust and gas out into space that can become the ingredients for coming generations of stars and planets, and with them the potential for new life," says Daniel Tafoya.

Since the 15 stars seem to be evolving on a human timescale, the team plan to keep monitoring them with Alma and with other radio telescopes. With the future telescopes of the SKA Observatory, they hope to study how the stars form their jets and change their surroundings. They also hope to find more -- if there are any.

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Darwin’s finches forced to 'evolve'

Spending time with offspring is beneficial to development, but it's proving lifesaving to Galápagos Islands Darwin's finches studied by Flinders University experts.

A new study, published in Proceedings of the Royal Society B, has found evidence Darwin's finch females that spend longer inside the nest can ward off deadly larvae of the introduced avian vampire fly, which otherwise enter and consume the growing chicks.

The maternal buffer is a life-saver, according to the research, especially during the first days after hatching, when chicks are blind, helpless and cannot preen. Although older offspring still have to contend with the larvae, they are better able to preen themselves, and may dislodge and occasionally eat some of them.

"The pair male is also essential for success of the chicks. If he feeds the offspring a lot, the mother can remain inside the nest for longer," says Flinders University Professor Sonia Kleindorfer, who is also affiliated with the University of Vienna.

"Timing is everything. The female must forgo foraging herself, and her persistence is strongly influenced by good food provisioning of her offspring by the male."

The unintentionally introduced avian vampire fly, an invasive species on the Galápagos Islands, enters Darwin's finch nests when attending parents are absent.

The 17 Darwin's finch species on the Galápagos Islands are a textbook example of a rapid adaptive radiation: each species has a unique beak shape suited to extract resources from a different ecological niche. However, since being first observed in Darwin's finch nests in 1997, the avian vampire fly has been parasitising nestlings and changing the beak and behaviour of its Darwin's finch hosts.

The fly lays eggs that hatch into larvae that feed on the developing chicks, killing most chicks and causing beak deformation in the survivors.

"What we show in this publication is that longer female in-nest attendance of chicks predicts the number of parasites in the nest," says Professor Kleindorfer.

"The new research findings are significant because they show that 'just being there' can be a form of front-line defence against threats to offspring survival."

British naturalist Charles Darwin's theory of evolution by natural selection was developed while observing plants and animals in various environments, including the Galápagos Islands, where in 1835 he noted the rich diversity of endemic plants, birds and reptiles.

Female Darwin's finches provide much longer in-nest care to young offspring than males, and presence inside the nest is needed to fend off parasites. For this reason, females themselves may incur higher survival costs as they attempt to save their offspring.

Monitoring survivorship of female birds is often more difficult than for males since male Darwin's finches produce a loud advertisement song but females to not.

Usually we think of active defending males as contributing more to offspring survival than females that incubate eggs or brood young chicks, adds Flinders University researcher Dr Andrew Katsis.

"We know from long-term monitoring of Darwin's finches, from recapture and resighting data since 2000, that annual survivorship in females is much lower than in males, and over 50% of male Darwin's finches sing at the nest but don't attract a female," he says.

"Combined, these factors suggest that higher female mortality, and higher parental care costs carried by females, may be a contributing factor."

High-quality females that can sustain longer in-nest parental care with less feeding opportunity for themselves, paired with males that increase feeding to the offspring, have better chances to produce offspring in a vampire fly-dominated environment, the research concludes.

"Control measures are urgently needed to save Darwin's finches from extinction," the scientists say in another new publication in Birds.

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