Birds migrate away from diseases

Migrating geese.

In a unique study, researchers at Lund University in Sweden have mapped the origins of migratory birds. They used the results to investigate and discover major differences in the immune systems of sedentary and migratory birds. The researchers conclude that migratory species benefit from leaving tropical areas when it is time to raise their young -- as moving away from diseases in the tropics enables them to survive with a less costly immune system.

Analysing the genealogy of over 1300 song bird species, passerines, enabled the researchers to establish that both sedentary birds, which do not leave northern Europe in the winter, and migratory birds, which breed in Europe but spend the winter close to the equator, originate from Africa.

The researchers then went on to study the immune system in three different groups: sedentary birds in tropical Africa, European sedentary birds, and migratory birds. Their findings show that African sedentary birds have a more varied and extensive immune system than that of both European sedentary birds and migratory birds.

Evolution has quite simply ensured that bird species migrating to Europe were equipped with a much less variable immune system, as Europe has far fewer diseases than the tropics. The African sedentary species probably need a more advanced immune system to deal with the richer flora of pathogens to which they are exposed.

"What really surprises me is that the immune systems of migratory birds show a similarly low variation to that of European sedentary birds. After all, migratory birds don't only need to resist diseases in Europe, but also during their migration and in the tropics," says Helena Westerdahl, one of the researchers behind the study.

To explain the surprising result, the researchers propose the idea that the costs associated with a strong and complex immune system could be much higher than anyone previously thought. Examples of these costs could be autoimmunity and other immune system diseases such as chronic inflammation.

Despite the migratory birds having to deal with pathogens both in Europe and tropical Africa, they have thus lost much of the variation and complexity in their immune system compared to their African ancestors. According to the researchers, this indicates that dealing with pathogens is most difficult for the birds the first time they are exposed to them. For migratory birds, this happens in Europe where they raise their young and there are not as many different pathogens.

"When the migratory birds breed, they have moved away from many diseases and therefore do not need an immune system that is equally varied. Another advantage is that the risk of damage caused by the immune system drops considerably if the immune system is less complex," says researcher Emily O'Connor.

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Melting of Arctic mountain glaciers unprecedented in the past 400 years

Scientists spent a month in Denali National Park in 2013 drilling ice cores from the summit plateau of Mt. Hunter. The ice cores showed the glaciers on Mt. Hunter are melting more now than at any time in the past 400 years.

Glaciers in Alaska's Denali National Park are melting faster than at any time in the past four centuries because of rising summer temperatures, a new study finds.

New ice cores taken from the summit of Mt. Hunter in Denali National Park show summers there are least 1.2-2 degrees Celsius (2.2-3.6 degrees Fahrenheit) warmer than summers were during the 18th, 19th, and early 20th centuries. The warming at Mt. Hunter is about double the amount of warming that has occurred during the summer at areas at sea level in Alaska over the same time period, according to the new research.

The warmer temperatures are melting 60 times more snow from Mt. Hunter today than the amount of snow that melted during the summer before the start of the industrial period 150 years ago, according to the study. More snow now melts on Mt. Hunter than at any time in the past 400 years, said Dominic Winski, a glaciologist at Dartmouth College in Hanover, New Hampshire and lead author of the new study published in the Journal of Geophysical Research: Atmospheres, a journal of the American Geophysical Union.

The new study's results show the Alaska Range has been warming rapidly for at least a century. The Alaska Range is an arc of mountains in southern Alaska home to Denali, North America's highest peak.

The warming correlates with hotter temperatures in the tropical Pacific Ocean, according to the study's authors. Previous research has shown the tropical Pacific has warmed over the past century due to increased greenhouse gas emissions.

The study's authors conclude warming of the tropical Pacific Ocean has contributed to the unprecedented melting of Mt. Hunter's glaciers by altering how air moves from the tropics to the poles. They suspect melting of mountain glaciers may accelerate faster than melting of sea level glaciers as the Arctic continues to warm.

Understanding how mountain glaciers are responding to climate change is important because they provide fresh water to many heavily-populated areas of the globe and can contribute to sea level rise, Winski said.

"The natural climate system has changed since the onset of the anthropogenic era," he said. "In the North Pacific, this means temperature and precipitation patterns are different today than they were during the preindustrial period."

Assembling a long-term temperature record

Winski and 11 other researchers from Dartmouth College, the University of Maine and the University of New Hampshire drilled ice cores from Mt. Hunter in June 2013. They wanted to better understand how the climate of the Alaska Range has changed over the past several hundred years, because few weather station records of past climate in mountainous areas go back further than 1950.

The research team drilled two ice cores from a glacier on Mt. Hunter's summit plateau, 13,000 feet above sea level. The ice cores captured climate conditions on the mountain going back to the mid-17th century.

The physical properties of the ice showed the researchers what the mountain's past climate was like. Bands of darker ice with no bubbles indicated times when snow on the glacier had melted in past summers before re-freezing.

Winski and his team counted all the dark bands -- the melt layers -- from each ice core and used each melt layer's position in the core to determine when each melt event occurred. The more melt events they observed in a given year, the warmer the summer.

They found melt events occur 57 times more frequently today than they did 150 years ago. In fact, they counted only four years with melt events prior to 1850. They also found the total amount of annual meltwater in the cores has increased 60-fold over the past 150 years.

The surge in melt events corresponds to a summer temperature increase of at least 1.2-2 degrees Celsius (2.2-3.6 degrees Fahrenheit) relative to the warmest periods of the 18th and 19th centuries, with nearly all of the increase occurring in the last 100 years. Because there were so few melt events before the start of the 20th century, the temperature change over the past few centuries could be even higher, Winski said.

Connecting the Arctic to the tropics

The research team compared the temperature changes at Mt. Hunter with those from lower elevations in Alaska and in the Pacific Ocean. Glaciers on Mt. Hunter are easily influenced by temperature variations in the tropical Pacific Ocean because there are no large mountains to the south to block incoming winds from the coast, according to the researchers.

They found during years with more melt events on Mt. Hunter, tropical Pacific temperatures were higher. The researchers suspect warmer temperatures in the tropical Pacific Ocean amplify warming at high elevations in the Arctic by changing air circulation patterns. Warmer tropics lead to higher atmospheric pressures and more sunny days over the Alaska Range, which contribute to more glacial melting in the summer, Winski said.

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Outback radio telescope listens in on interstellar visitor

This artist's impression shows the first interstellar asteroid: `Oumuamua.

A telescope in outback Western Australia has been used to listen to a mysterious cigar-shaped object that entered our Solar System late last year.

The unusual object -- known as 'Oumuamua -- came from another solar system, prompting speculation it could be an alien spacecraft.

So astronomers went back through observations from the Murchison Widefield Array (MWA) telescope to check for radio transmissions coming from the object between the frequencies of 72 and 102MHz -- similar to the frequency range in which FM radio is broadcast.

While they did not find any signs of intelligent life, the research helped expand the search for extra-terrestrial intelligence (SETI) from distant stars to objects closer to home.

When 'Oumuamua was first discovered, astronomers thought it was a comet or an asteroid from within the Solar System. But after studying its orbit and discovering its long, cylindrical shape, they realised 'Oumuamua was neither and had come from interstellar space.

Telescopes around the world trained their gaze on the mysterious visitor in an effort to learn as much as possible before it headed back out of the Solar System, becoming too faint to observe in detail.

John Curtin Distinguished Professor Steven Tingay, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the MWA team did not initially set out to find 'Oumuamua.

"We didn't set out to observe this object with the MWA but because we can see such a large fraction of the sky at once, when something like this happens, we're able to go back through the data and analyse it after the fact," Professor Tingay said.

"If advanced civilizations do exist elsewhere in our galaxy, we can speculate that they might develop the capability to launch spacecraft over interstellar distances and that these spacecraft may use radio waves to communicate."

"Whilst the possibility of this is extremely low, possibly even zero, as scientists it's important that we avoid complacency and examine observations and evidence without bias."

The MWA is located in Western Australia's remote Murchison region, one of the most radio-quiet areas on the planet and far from human activity and radio interference caused by technology.

It is made up of thousands of antennas attached to hundreds of "tiles" that dot the ancient landscape, relentlessly observing the heavens day after day, night after night.

Professor Tingay said the research team was able to look back through all of the MWA's observations from November, December and early January, when 'Oumuamua was between 95 million and 590 million kilometres from Earth.

"We found nothing, but as the first object of its class to be discovered, `Oumuamua has given us an interesting opportunity to expand the search for extra-terrestrial intelligence from traditional targets such as stars and galaxies to objects that are much closer to Earth.

"This also allows for searches for transmitters that are many orders of magnitude less powerful than those that would be detectable from a planet orbiting even the most nearby stars."

'Oumuamua was first discovered by the Pan-STARRS project at the University of Hawaii in October.

Its name loosely means "a messenger that reaches out from the distant past" in Hawaiian, and is the first known interstellar object to pass through our Solar System.

Combining observations from a host of telescopes, scientists have determined that `Oumuamua is most likely a cometary fragment that has lost much of its surface water because it was bombarded by cosmic rays on its long journey through interstellar space.

Researchers have now suggested there could be more than 46 million similar interstellar objects crossing the Solar System every year.

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Water appeared while Earth was still growing

Meteorites such as these carbonaceous chondrites are thought to have delivered water to the Earth--but an outstanding question is when. A new study points to the early incorporation of water in the growing Earth.

Up until about ten years ago, scientists thought they had a pretty good picture of how the moon and Earth came to co-exist. Then more precise measurements blew it all wide open, and scientists are still struggling to reconcile them.

As part of that effort, a team including UChicago cosmochemist Nicolas Dauphas performed the largest study to date of oxygen isotopes in lunar rocks, and found a small but measurable difference in the makeup of the moon and Earth.

Published March 28 in Science Advances, the research proposes that Earth acquired the majority of its water during the main stage of its growth -- which counters a popular theory.

The most widely accepted theory of the origin of the Moon speculates that a giant object smashed into the proto-Earth at just enough velocity that part of both bodies broke off and formed the moon. The Earth has a little of the moon and the moon has more of the Earth, but they'd be mostly different objects. Early measurements -- many taken by the late UChicago geochemist Robert Clayton -- did not have sufficient precision to tell the Moon and Earth apart.

But in the last decade, Dauphas said, it became clear this picture wasn't quite right. Elements can come in different forms, called isotopes, and these give scientists clues to the rock's origin. As ways to measure isotopes improved, scientists discovered striking similarities between the moon and the Earth. Referred to as the "lunar isotopic crisis," this was a problem for the main theory of lunar formation, because it's highly unlikely the isotopes would be exactly the same for two random objects in the solar system.

"This, to my mind, is one of the most compelling questions in modern planetary science," said Dauphas, head of the Origins Laboratory and professor in the Department of Geophysical Sciences and the Enrico Fermi Institute. "Right now it's completely open. It's amazing to still be asking this."

One theory to explain the matching isotopes was a scenario in which the proto-Earth was totally vaporized by one or more giant impacts, and both it and the moon formed out of the cloud. But one of the major uncertainties is that scientists have reached different conclusions about how different the oxygen isotopes are between lunar and terrestrial rocks.

Seeking to clarify the issue, the researchers measured the oxygen isotopes of both lunar and terrestrial rocks with extremely high precision. They found a very small, but detectable difference between the isotopes between the two bodies.

To explain the near match, the authors turn to water. A popular theory is that the Earth got the majority of its water after the great impact, as more objects containing ice hit the Earth as meteorites. (The term to describe it is late veneer, meaning that water is delivered to the Earth as a veneer after the Earth has completed its growth.)

But if most of Earth's water was delivered via later meteorites, this would have shown up as a greater isotopic difference than what the researchers measured -- as water-bearing meteorites have unusual mixtures of oxygen isotopes.

Their model suggests that only 5 percent to 30 percent of all the water on Earth would have arrived on meteorites after the great impact.

Dauphas noted the picture is still evolving because depending on which element you measure, differences between the moon and Earth could be found. "Oxygen, titanium, tungsten -- these are the ones that are still keeping us up at night," he said.

The question of how planets acquire water is interesting for a number of reasons, Dauphas said, including the search for distant exoplanets that might have water -- and thus a similar kind of life.

Read more at Science Daily

Giant ichthyosaur is one of largest animals ever

Jaw bone of giant ichthyosaur.

The 205 million-year-old jaw bone of a prehistoric reptile belongs to 'one of the largest animals ever' say a group of international palaeontologists.

The new discovery has also solved a 150 year old mystery of supposed 'dinosaur bones' from the UK.

The bone belongs to a giant ichthyosaur, a type of prehistoric aquatic reptile, and experts estimate the length of this specimen's body would have been up to 26 metres. Approaching the size of a blue whale.

Fossil collector and co-author of the study, Paul de la Salle, found the bone on the beach at Lilstock, Somerset in May 2016. He later returned to the site and found even more pieces that together measured about one metre in length.

Paul said "Initially, the bone just looked like a piece of rock but, after recognising a groove and bone structure, I thought it might be part of a jaw from an ichthyosaur and immediately contacted ichthyosaur experts Dean Lomax (University of Manchester) and Prof. Judy Massare (SUNY College at Brockport, NY, USA) who expressed interest in studying the specimen. I also contacted Dr Ramues Gallois, a geologist who visited the site and determined the age of the specimen stratigraphically.

Lomax and Massare identified the specimen as an incomplete bone (called a surangular) from the lower jaw of a giant ichthyosaur. The bone would have made up only a portion of the entire skull. They compared it with several ichthyosaurs and visited the Royal Tyrrell Museum of Palaeontology in Alberta, Canada, and examined the largest ichthyosaur known, the shastasaurid Shonisaurus sikanniensis, which is 21 m long. They found similarities between the new specimen and S. sikanniensis which suggest the Lilstock specimen belongs to a giant shastasaurid-like ichthyosaur.

"As the specimen is represented only by a large piece of jaw, it is difficult to provide a size estimate, but by using a simple scaling factor and comparing the same bone in S. sikanniensis, the Lilstock specimen is about 25% larger. Other comparisons suggest the Lilstock ichthyosaur was at least 20-25 m. Of course, such estimates are not entirely realistic because of differences between species. Nonetheless, simple scaling is commonly used to estimate size, especially when comparative material is scarce." Added Lomax.

In 1850, a large bone was described from the Late Triassic (208 million-years-old) of Aust Cliff, Gloucestershire, UK. Four other similarly incomplete bones were also found and described. Two of them are now missing and presumed destroyed. They have been identified as the limb bones of several dinosaurs (stegosaurs and sauropods), indeterminate dinosaurs and other reptiles.

However, with the discovery of the Lilstock specimen, this new study refutes previous identifications and also the most recent assertion that the Aust bones represent an early experiment of dinosaur-like gigantism in terrestrial reptiles. They are, in fact, jaw fragments of giant, previously unrecognised ichthyosaurs.

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Why expressive brows might have mattered in human evolution

Eyebrows on fleek: Model of a modern human skull next to Kabwe 1.

Highly mobile eyebrows that can be used to express a wide range of subtle emotions may have played a crucial role in human survival, new research from the University of York suggests.

Like the antlers on a stag, a pronounced brow ridge was a permanent signal of dominance and aggression in our early ancestors, which modern humans traded in for a smooth forehead with more visible, hairy eyebrows capable of a greater range of movement.

Mobile eyebrows gave us the communication skills to establish large, social networks; in particular to express more nuanced emotions such as recognition and sympathy, allowing for greater understanding and cooperation between people.

The study contributes to a long-running academic debate about why other hominins, including our immediate ancestors, had gigantic brow ridges while anatomically modern humans evolved flatter foreheads.

Senior author of the paper, Paul O'Higgins, Professor of Anatomy at the University of York, said: "Looking at other animals can offer interesting clues as to what the function of a prominent brow ridge may have been. In mandrills, dominant males have brightly coloured swellings on either side of their muzzles to display their status. The growth of these lumps is triggered by hormonal factors and the bones underlying them are pitted with microscopic craters -- a feature that can also be seen in the brow bones of archaic hominins."

"Sexually dimorphic display and social signalling is a convincing explanation for the jutting brows of our ancestors. Their conversion to a more vertical brow in modern humans allowed for the display of friendlier emotions which helped form social bonds between individuals."

Using 3D engineering software, the researchers looked at the iconic brow ridge of a fossilised skull, known as Kabwe 1, held in the collections of the National History Museum.

It belonged to a species of archaic hominin -- Homo heidelbergensis, who lived between 600,000 and 200,000 years ago.

The researchers discounted two theories commonly put forward to explain protruding brow ridges: that they were needed to fill the space where the flat brain cases and eye sockets of archaic hominins met, and that the ridge acted to stabilise their skulls from the force of chewing.

Professor O'Higgins said: "We used modelling software to shave back Kabwe's huge brow ridge and found that the heavy brow offered no spatial advantage as it could be greatly reduced without causing a problem. Then we simulated the forces of biting on different teeth and found that very little strain was placed on the brow ridge. When we took the ridge away there was no effect on the rest of the face when biting.

"Since the shape of the brow ridge is not driven by spatial and mechanical requirements alone, and other explanations for brow ridges such as keeping sweat or hair out of eyes have already been discounted, we suggest a plausible contributing explanation can be found in social communication."

According to the researchers, our communicative foreheads started off as a side-effect of our faces getting gradually smaller over the past 100,000 years. This process has become particularly rapid in last 20,000 years and more recently, as we switched from being hunter gatherers to agriculturalists -- a lifestyle that meant less variety in both diet and physical effort.

Co-author of the paper, Dr Penny Spikins from the Department of Archaeology at the University of York, said: "Modern humans are the last surviving hominin. While our sister species the Neanderthals were dying out, we were rapidly colonising the globe and surviving in extreme environments. This had a lot to do with our ability to create large social networks -- we know, for example, that prehistoric modern humans avoided inbreeding and went to stay with friends in distant locations during hard times.

"Eyebrow movements allow us to express complex emotions as well as perceive the emotions of others. A rapid "eyebrow flash" is a cross-cultural sign of recognition and openness to social interaction and pulling our eyebrows up at the middle is an expression of sympathy. Tiny movements of the eyebrows are also a key component to identifying trustworthiness and deception. On the flip side it has been shown that people who have had botox which limits eyebrow movement are less able to empathise and identify with the emotions of others.

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First human migration out of Africa more geographically widespread than previously thought

Fossil finger bone of Homo sapiens from the Al Wusta site, Saudi Arabia.

A project led by the Max Planck Institute for the Science of Human History has discovered a fossilized finger bone of an early modern human in the Nefud Desert of Saudi Arabia, dating to approximately 90,000 years ago. The discovery, described in Nature Ecology and Evolution, is the oldest directly dated Homo sapiens fossil outside of Africa and the Levant and indicates that early dispersals into Eurasia were more expansive than previously thought.

Researchers conducting archaeological fieldwork in the Nefud Desert of Saudi Arabia have discovered a fossilized finger bone of an early member of our species, Homo sapiens. The discovery is the oldest directly dated Homo sapiens fossil outside of Africa and the immediately adjacent Levant, and indicates that early dispersals into Eurasia were more expansive than previously thought. Prior to this discovery, it was thought that early dispersals into Eurasia were unsuccessful and remained restricted to the Mediterranean forests of the Levant, on the doorstep of Africa. The finding from the Al Wusta site shows that there were both multiple dispersals out of Africa, and these spread further than previously known.

Oldest directly dated Homo sapiens fossil outside of Africa and the Levant

The results, published in Nature Ecology and Evolution, detail the discovery made at the site of Al Wusta, an ancient fresh-water lake located in what is now the hyper-arid Nefud Desert. Numerous animal fossils, including those of hippopotamus and tiny fresh water snails were found at Al Wusta, as well as abundant stone tools made by humans. Among these finds was a well preserved and small fossil, just 3.2 cm long, which was immediately recognized as a human finger bone. The bone was scanned in three dimensions and its shape compared to various other finger bones, both of recent Homo sapiens individuals and bones from other species of primates and other forms of early humans, such as Neanderthals. The results conclusively showed that the finger bone, the first ancient human fossil found in Arabia, belonged to our own species. Using a technique called uranium series dating, a laser was used to make microscopic holes in the fossil and measure the ratio between tiny traces of radioactive elements. These ratios revealed that the fossil was 88,000 years old. Other dates obtained from associated animals fossils and sediments converged to a date of approximately 90,000 years ago. Further environmental analyses also revealed the site to have been a freshwater lake in an ancient grassland environment far removed from today's deserts.

Lead author Dr. Huw Groucutt, of the University of Oxford and the Max Planck Institute for the Science of Human History, states, "This discovery for the first time conclusively shows that early members of our species colonized an expansive region of southwest Asia and were not just restricted to the Levant. The ability of these early people to widely colonize this region casts doubt on long held views that early dispersals out of Africa were localized and unsuccessful."

Modern deserts of the Arabian Peninsula were once lush grasslands that humans were able to colonize

Project Lead, Professor Michael Petraglia of the Max Planck Institute for the Science of Human History adds, "The Arabian Peninsula has long been considered to be far from the main stage of human evolution. This discovery firmly puts Arabia on the map as a key region for understanding our origins and expansion to the rest of the world. As fieldwork carries on, we continue to make remarkable discoveries in Saudi Arabia."

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Brewing up Earth's earliest life

White Island, New Zealand. Researchers have found that a class of molecules called sulfidic anions may have been abundant in Earth’s lakes and rivers.

Around 4 billion years ago, Earth was an inhospitable place, devoid of oxygen, bursting with volcanic eruptions, and bombarded by asteroids, with no signs of life in even the simplest forms. But somewhere amid this chaotic period, the chemistry of the Earth turned in life's favor, giving rise, however improbably, to the planet's very first organisms.

What prompted this critical turning point? How did living organisms rally in such a volatile world? And what were the chemical reactions that brewed up the first amino acids, proteins, and other building blocks of life? These are some of the questions researchers have puzzled over for decades in trying to piece together the origins of life on Earth.

Now planetary scientists from MIT and the Harvard-Smithsonian Center for Astrophysics have identified key ingredients that were present in large concentrations right around the time when the first organisms appeared on Earth.

The researchers found that a class of molecules called sulfidic anions may have been abundant in Earth's lakes and rivers. They calculate that, around 3.9 billion years ago, erupting volcanoes emitted huge quantities of sulfur dioxide into the atmosphere, which eventually settled and dissolved in water as sulfidic anions -- specifically, sulfites and bisulfites. These molecules likely had a chance to accumulate in shallow waters such as lakes and rivers.

"In shallow lakes, we found these molecules would have been an inevitable part of the environment," says Sukrit Ranjan, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Whether they were integral to the origin of life is something we're trying to work out."

Preliminary work by Ranjan and his collaborators suggest that sulfidic anions would have sped up the chemical reactions required to convert very simple prebiotic molecules into RNA, a genetic building block of life.

"Prior to this work, people had no idea what levels of sulfidic anions were present in natural waters on early Earth; now we know what they were," Ranjan says. "This fundamentally changes our knowledge of early Earth and has had direct impact on laboratory studies of the origin of life."

Ranjan and his colleagues published their results today in the journal Astrobiology.

Setting early Earth's stage

In 2015, chemists from Cambridge University, led by John Sutherland, who is a co-author on the current study, discovered a way to synthesize the precursors to RNA using just hydrogen cyanide, hydrogen sulfide, and ultraviolet light -- all ingredients that are thought to have been available on early Earth, before the appearance of the first life forms.

From a chemistry point of view, the researchers' case was convincing: The chemical reactions they carried out in the laboratory overcame longstanding chemical challenges, to successfully yield the genetic building blocks to life. But from a planetary science standpoint, it was unclear whether such ingredients would have been sufficiently abundant to jumpstart the first living organisms.

For instance, comets may have had to rain down continuously to bring enough hydrogen cyanide to Earth's surface. Meanwhile, hydrogen sulfide, which would have been released in huge amounts by volcanic eruptions, would have mostly stayed in the atmosphere, as the molecule is relatively insoluble in water, and therefore would not have had regular opportunities to interact with hydrogen cyanide.

Instead of approaching the origins-of-life puzzle from a chemistry perspective, Ranjan looked at it from a planetary perspective, attempting to identify the actual conditions that might have existed on early Earth, around the time the first organisms appeared.

"The origins-of-life field has traditionally been led by chemists, who try to figure out chemical pathways and see how nature might have operated to give us the origins of life," Ranjan says. "They do a really great job of that. What they don't do in as much detail is, they don't ask what were conditions on early Earth like before life? Could the scenarios they invoke have actually happened? They don't know as much what the stage setting was."

Cranking up the ingredients for life

In August 2016, Ranjan gave a talk at Cambridge University about volcanism on Mars and the types of gases that would have been emitted by such eruptions in the red planet's oxygenless atmosphere. Chemists at the talk realized that the same general conditions would have occurred on Earth prior to the start of life.

"They took away from that [talk] that, on early Earth, you don't have much oxygen, but you do have sulfur dioxide from volcanism," Ranjan recalls. "As a consequence, you should have sulfites. And they said, 'Can you tell us how much of this molecule there would have been?' And that's what we set out to constrain."

To do so, he started with a volcanism model developed previously by Sara Seager, MIT's Class of 1941 Professor of Planetary Sciences, and her former graduate student Renyu Hu.

"They did a study where they asked, 'Suppose you take the Earth and just crank up the amount of volcanism on it. What concentrations of gases do you get in the atmosphere?'" Ranjan says.

He consulted the geological record to determine the amount of volcanism that likely took place around 3.9 billion years ago, around the time the first life forms are thought to have appeared, then looked up the types and concentrations of gases that this amount of volcanism would have produced according to Seager and Hu's calculations.

Next, he wrote a simple aqueous geochemistry model to calculate how much of these gases would have been dissolved in shallow lakes and reservoirs -- environments that would have been more conducive to concentrating life-forming reactions, versus vast oceans, where molecules could easily dissipate.

Interestingly, he consulted the literature in a rather unexpected subject while conducting these calculations: winemaking -- a science that involves, in part, dissolving sulfur dioxide in water to produce sulfites and bisulfites under oxygenless conditions similar to those on early Earth.

"When we were working on this paper, a lot of the constants and data we pulled out were from the wine chemistry journals, because it's where we have anoxic environments here on modern Earth," Ranjan says. "So we took aspects of wine chemistry and asked: 'Suppose we have x amount of sulfur dioxide. How much of that dissolves in water, and then what does it become?'"

Community cross-talk

Ultimately, he found that, while volcanic eruptions would have spewed huge quantities of both sulfur dioxide and hydrogen sulfide into the atmosphere, it was the former that dissolved more easily in shallow waters, producing large concentrations of sulfidic anions, in the form of sulfites and bisulfites.

"During major volcanic eruptions, you might have had up to millimolar levels of these compounds, which is about laboratory-level concentrations of these molecules, in the lakes," Ranjan says. "That is a titanic amount."

The new results point to sulfites and bisulfites as a new class of molecules -- ones that were actually available on early Earth -- that chemists can now test in the lab, to see whether they can synthesize from these molecules the precursors for life.

Early experiments led by Ranjan's colleagues suggest that sulfites and bisulfites may have indeed encouraged biomolecules to form. The team carried out chemical reactions to synthesize ribonucleotides with sulfites and bisulfites, versus with hydrosulfide, and found the former were able to produce ribonucleotides and related molecules 10 times faster than the latter, and at higher yields. More work is needed to confirm whether sulfidic anions were indeed early ingredients in brewing up the first life forms, but there is now little doubt that these molecules were part of the prebiotic milieu.

Read more at Science Daily

Dead star circled by light

This new picture created from images from telescopes on the ground and in space tells the story of the hunt for an elusive missing object hidden amid a complex tangle of gaseous filaments in one of our nearest neighboring galaxies, the Small Magellanic Cloud. The reddish background image comes from the NASA/ESA Hubble Space Telescope and reveals the wisps of gas forming the supernova remnant 1E 0102.2-7219 in green. The red ring with a dark center is from the MUSE instrument on ESO's Very Large Telescope and the blue and purple images are from the NASA Chandra X-Ray Observatory. The blue spot at the center of the red ring is an isolated neutron star with a weak magnetic field, the first identified outside the Milky Way.

Spectacular new pictures, created from images from both ground- and space-based telescopes, tell the story of the hunt for an elusive missing object hidden amid a complex tangle of gaseous filaments in the Small Magellanic Cloud, about 200,000 light-years from Earth.

New data from the MUSE instrument on ESO's Very Large Telescope in Chile has revealed a remarkable ring of gas in a system called 1E 0102.2-7219, expanding slowly within the depths of numerous other fast-moving filaments of gas and dust left behind after a supernova. This discovery allowed a team led by Frédéric Vogt, an ESO Fellow in Chile, to track down the first ever isolated neutron star with low magnetic field located beyond our own Milky Way galaxy.

The team noticed that the ring was centred on an X-ray source that had been noted years before and designated p1. The nature of this source had remained a mystery. In particular, it was not clear whether p1 actually lies inside the remnant or behind it. It was only when the ring of gas -- which includes both neon and oxygen -- was observed with MUSE that the science team noticed it perfectly circled p1. The coincidence was too great, and they realised that p1 must lie within the supernova remnant itself. Once p1's location was known, the team used existing X-ray observations of this target from the [Chandra X-ray Observatory]  to determine that it must be an isolated neutron star, with a low magnetic field.

In the words of Frédéric Vogt: "If you look for a point source, it doesn't get much better than when the Universe quite literally draws a circle around it to show you where to look."

When massive stars explode as supernovae, they leave behind a curdled web of hot gas and dust, known as a supernova remnant. These turbulent structures are key to the redistribution of the heavier elements -- which are cooked up by massive stars as they live and die -- into the interstellar medium, where they eventually form new stars and planets.

Typically barely ten kilometres across, yet weighing more than our Sun, isolated neutron stars with low magnetic fields are thought to be abundant across the Universe, but they are very hard to find because they only shine at X-ray wavelengths. The fact that the confirmation of p1 as an isolated neutron star was enabled by optical observations is thus particularly exciting.

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Giant solar tornadoes put researchers in a spin

Composite image of an erupting solar prominence observed by SDO on Aug. 31, 2012.

Despite their appearance solar tornadoes are not rotating after all, according to a European team of scientists. A new analysis of these gigantic structures, each one several times the size of the Earth, indicates that they may have been misnamed because scientists have so far only been able to observe them using 2-dimensional images. Dr Nicolas Labrosse will present the work, carried out by researchers at the University of Glasgow, Paris Observatory, University of Toulouse, and Czech Academy of Sciences, at the European Week of Astronomy and Space Science (EWASS) in Liverpool on Friday 6 April.

Solar tornadoes were first observed in the early 20th century, and the term was re-popularised a few years ago when scientists looked at movies obtained by the AIA instrument on the NASA Solar Dynamics Observatory (SDO). These show hot plasma in extreme ultraviolet light apparently rotating to form a giant structure taking the shape of a tornado (as we know them on Earth).

Now, using the Doppler effect to add a third dimension to their data, the scientists have been able to measure the speed of the moving plasma, as well as its direction, temperature and density. Using several years' worth of observations, they were able to build up a more complete picture of the magnetic field structure that supports the plasma, in structures known as prominences.

Dr Nicolas Labrosse, lead scientist in the study, explains: "We found that despite how prominences and tornadoes appear in images, the magnetic field is not vertical, and the plasma mostly moves horizontally along magnetic field lines. However we see tornado-like shapes in the images because of projection effects, where the line of sight information is compressed onto the plane of the sky."

Dr Arturo López Ariste, another member of the team, adds: "The overall effect is similar to the trail of an aeroplane in our skies: the aeroplane travels horizontally at a fixed height, but we see that the trail starts above our heads and ends up on the horizon. This doesn't mean that it has crashed!"

Giant solar tornadoes -- formally called tornado prominences -- have been observed on the Sun for around a hundred years. They are so called because of their striking shape and apparent resemblance to tornadoes on Earth, but that is where the comparison ends.

Whereas terrestrial tornadoes are formed from intense winds and are very mobile, solar tornadoes are instead magnetized gas. They seem to be rooted somewhere further down the solar surface, and so stay fixed in place.

"They are associated with the legs of solar prominences -- these are beautiful concentrations of cool plasma in the very hot solar corona that can easily be seen as pink structures during total solar eclipses," adds Labrosse.

"Perhaps for once the reality is less complicated than what we see!" comments Dr Brigitte Schmieder, another scientist involved in the work.

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