Apr 7, 2018

Hunting for dark matter in the smallest galaxies in the Universe

Dark matter makes up most of the mass of the Universe, yet it remains elusive.
Astrophysicists from the University of Surrey and the University of Edinburgh have created a new method to measure the amount of dark matter at the centre of tiny "dwarf" galaxies.

Dark matter makes up most of the mass of the Universe, yet it remains elusive. Depending on its properties, it can be densely concentrated at the centres of galaxies, or more smoothly distributed over larger scales. By comparing the distribution of dark matter in galaxies with detailed models, researchers can test or rule out different dark matter candidates.

The tightest constraints on dark matter come from the very smallest galaxies in the Universe, "dwarf galaxies." The smallest of these contain just a few thousand or tens of thousands of stars -- so-called "ultra-faint" dwarfs. Such tiny galaxies, found orbiting close to the Milky Way, are made up almost entirely of dark matter. If the distribution of dark matter in these tiny galaxies could be mapped out it could provide new and exciting information about its nature. However, being entirely devoid of gas and containing very few stars, until recently there was no viable method for making this measurement.

In a study published by the Monthly Notices of the Royal Astronomical Society (MNRAS), a team of scientists from the University of Surrey have developed a new method to calculate the inner dark matter density of dwarf galaxies, even if they have no gas and very few stars. The key to the method is to make use of one or more dense star clusters orbiting close to the centre of the dwarf.

Star clusters are gravitationally bound collections of stars that orbit inside galaxies. Unlike galaxies, star clusters are so dense that their stars gravitationally scatter from one another causing them to slowly expand. The research team made the key new insight when they realised that the rate of this expansion depends on the gravitational field that the star cluster orbits in and, therefore, on the distribution of dark matter in the host galaxy. The team used a large suite of computer simulations to show how the structure of star clusters is sensitive to whether dark matter is densely packed at the centre of galaxies, or more smoothly distributed. The team then applied their method to the recently discovered "ultra-faint" dwarf galaxy, Eridanus II, finding much less dark matter in its centre than many models would have predicted.

Dr Filippo Contenta from the University of Surrey and lead author of the study said: "We have developed a new tool to uncover the nature of dark matter and already the results are exciting. Eridanus II, one of the smallest galaxies known, has less dark matter in its centre than expected. If similar results are found for a larger sample of galaxies, this could have wide-ranging implications for the nature of dark matter."

Professor Mark Gieles, Professor of Astrophysics at the University of Surrey and Principal Investigator of the European Research Council (ERC) project that funded the project, added: "We started this ERC project with the hope that we could use star clusters to learn about dark matter so it is very exciting that it worked."

Professor Justin Read, a co-author on the study from the University of Surrey, added: "It is challenging to understand our results for Eridanus II if dark matter comprises a weakly interacting 'cold' particle -- the currently-favoured model for dark matter. One possibility is that the dark matter at the very centre of Eridanus II was "heated up" by violent star formation, as suggested by some recent numerical models. More tantalising, however, is the possibility is that dark matter is more complex than we have assumed to date."

Read more at Science Daily

Paucity of phosphorus hints at precarious path for extraterrestrial life

This is a composite of infrared (shown as red), visible (green) and ultraviolet (violet) images of the Crab Nebula, with IR enhanced and visible/UV balanced to yield neutral star colors.
Work by Cardiff University astronomers suggests there may be a cosmic lack of a chemical element essential to life. Dr Jane Greaves and Dr Phil Cigan will present their results at the European Week of Astronomy and Space Science in Liverpool.

Greaves has been searching for phosphorus in the universe, because of its link to life on Earth. If this element -- with the chemical code P -- is lacking in other parts of the cosmos, then it could be difficult for extra-terrestrial life to exist.

She explains: "Phosphorus is one of just six chemical elements on which Earth organisms depend, and it is crucial to the compound adenosine triphosphate (ATP), which cells use to store and transfer energy. Astronomers have just started to pay attention to the cosmic origins of phosphorus and found quite a few surprises. In particular, P is created in supernovae -- the explosions of massive stars -- but the amounts seen so far don't match our computer models. I wondered what the implications were for life on other planets if unpredictable amounts of P are spat out into space and later used in the construction of new planets."

The team used the UK's William Herschel Telescope, sited on La Palma in the Canary islands, to observe infrared light from phosphorus and iron in the Crab Nebula, a supernova remnant around 6500 light years away in the direction of the constellation of Taurus.

Cigan, an expert on these stellar remnants, says: "This is only the second such study of phosphorus that has been made. The first looked at the Cassiopeia A (Cas A) supernova remnant, and so we are able to compare two different stellar explosions and see if they ejected different proportions of phosphorus and iron. The first element supports life, while the second is a major part of our planet's core."

The astronomers struggled with foggy nights at the telescope, back in November 2017, and are only just starting to get scientific results from a few hours of data.

Cigan cautions "These are our preliminary results, which we extracted only in the last couple of weeks! But at least for the parts of the Crab Nebula we were able to observe so far, there seems to be much less phosphorus than in Cas A. The two explosions seem to differ from each other, perhaps because Cas A results from the explosion of a rare super-massive star. We've just asked for more telescope time to go back and check, in case we've missed some phosphorus-rich regions in the Crab Nebula."

The preliminary results suggest that material blown out into space could vary dramatically in chemical composition. Greaves remarks: "The route to carrying phosphorus into new-born planets looks rather precarious. We already think that only a few phosphorus-bearing minerals that came to the Earth -- probably in meteorites -- were reactive enough to get involved in making proto-biomolecules.

'If phosphorus is sourced from supernovae, and then travels across space in meteoritic rocks, I'm wondering if a young planet could find itself lacking in reactive phosphorus because of where it was born? That is, it started off near the wrong kind of supernova? In that case, life might really struggle to get started out of phosphorus-poor chemistry, on another world otherwise similar to our own."

Read more at Science Daily

Apr 6, 2018

Genetics of the modern heirs of the Inkas shed new lights about their origins and lineages

Iconic sacred citadelle of Machu Picchu, at the edge of the Andes and Amazon, symbol of the largest empire of the Pre Columbian Americas.
A multinational South American team from Peru, Brasil and Bolivia led by the Universidad de San Martin de Porres at Lima, Peru, published the first genetic study on the modern descendants of the imperial Inka lineages in the journal Molecular Genetics and Genomics. This work supported by funds from the Genographic Project (Geno 2.0), shows new insights about the Inkas origins and lineages.

The Inka people arrived to Cusco valley and in a few centuries they built the Tawantinsuyu, the largest empire in the Americas. The Tawantinsuyu was the cultural climax of 6,000 years of Central Andes civilizations overlapping modern countries of Peru, Bolivia, Ecuador, the South of Colombia and the North of Argentina and Chile. In contrast with the richness of archeological and cultural evidence, pre Columbian history vanishes in time as it intermingles with myths due to the lack of writing systems before the arrival of the European chroniclers. Very little is known about the Inka origins and some genetic information could help reconstruct part of their history. Unfortunately the mummies and bodily remains of the Inka emperors, worshiped as gods, were burnt and buried in unknown locations due to religious and political persecution by the Christian Conquistadors and Inquisitors, so no direct material remain to study their DNA. "Thus for now, only the genetic analysis of modern families of Inka descent could provide some clues about their ancestors" remarks geneticist Jose Sandoval, first author, working at Universidad de San Martin de Porres at Lima, Peru.

There were two foundational myths for the origin of the Inkas before they established in Cusco valley to build their capital city. One is that Manco Capac and Mama Ocllo, considered children of the Sun God and founder parents of the civilization, came from Lake Titicaca about 500 km southwards from the border of North Bolivia and South Peru, more or less the same region where Tiwanaku empire existed a few centuries before. The second myth narrates that four Ayar brothers, with divine powers, came out from the caves inside of a hill in the area of Paccarictambo, 50 km south of Cusco and only one of them, Manco, arrived to the Cusco valley. Concerning the succession of the rulers (between 12 to 14), most chroniclers mention only one patrilineal heritage, however other authors think that it was a complex selection of military and administrative skills not necessarily electing the son of a previous Inka. "A unique patrilineal cluster would be expected in the first case. In the second case, two or more patrilineal pattern will be evident" says geneticist Ricardo Fujita, senior author, also at Universidad de San Martin de Porres." The research team included historian Ronald Elward, who studied documentation of twelve Inka noble families and followed up from the conquista times to their contemporary descendants. "Most of them still living in the towns of San Sebastian and San Jeronimo, Cusco, Peru, at present, are probably the most homogeneous group of Inka lineage" says Elward.

Markers for Y chromosome and mtDNA were used for the genetic analysis of these families and compared with a database for 2400 native individuals from Peru, Bolivia, Ecuador and Brazil. "The results show distinctive patrilineal origins to two founder individuals who lived between 1000 to 1500 AD, a period between the decline of former Tiwanaku (south) and Wari (north) contemporary empires, and the rise of the Inca empire a few centuries later" says geneticist Fabricio Santos from the Universidad Federal de Minas Gerais at Belo Horizonte, Brazil. The first patrilineal haplotype named AWKI-1 (awki means crown prince in quechua language) is found in the putative families descending of 2 earlier Incas Yahuar Huacac and Viracocha. The same pattern of the Inca descendants was also found in individuals living south to Cusco, mainly in Aymaras of Peru and Bolivia. The second patrilineal haplotype named AWKI-2 was found in one descendant of a more recent Inca, Huayna Capac, father of the two brothers (Huascar and Atahualpa) who were fighting a fraternal war over the empire at the arrival of the Conquistadors. "AWKI-2 is also found in dozens of individuals from different locations in the Andes and occasionally in the Amazon, suggesting a populational expansion" says Dr. Santos.

"In addition to San Sebastian and San Jeronimo, most locations of AWKI-1, AWKI-2 were southwards to Cusco including the basin of lake Titicaca and neighboring Paccarictambo, in agreement with the two foundational myths of the Incas" says Ricardo Fujita, "probably two pictures at different times of the same journey with final destination Cusco" adds Fujita. "It is also remarkable that in these contemporary Inka noblility families there is a continuity since pre Columbian times" says Ronald Elward. The analysis of their mtDNA suggested a highly varied matrilineal marker whose counterparts are found all over the Andes reflecting a high genetic flow. "This probably reflects the political alliances by arranged marriages between Cusco nobility and daughters of lords of kingdoms and chiefdoms all over the empire" states Jose Sandoval.

This work is the continuation of several studies performed by the team to reconstruct South American history by Genetics and also funded by a previous grant of the Genographic Project (Geno 1.0) led in South America by Fabricio Santos. Two published works included the unique ancient roots of the Uros, people from the Floating Islands of the Lake Titicaca and the Quechwa-Lamistas in Peruvian Amazon. Modern Uros are Aymara speaking people that some have thought to be people from the Aymara ethnia who profited tourism by living on the floating islands. However the team showed that they were genetically isolated people who had lost their original Uro language, shifting to more the widely used Aymara language. On the other hand the Kechwa-Lamista are Amazonian people who speak the Andean Quechua language and they were presumed descendants of Andeans Chancas, former enemies of the Incas, and were chased by them towards the Amazon. DNA showed that they are actually descendants of linguistically different Amazonian people who were gathered by Catholic missions and were taught the Quechua language (learn by the missionaries at the Andes) for a better evangelization.

Read more at Science Daily

Older adults grow just as many new brain cells as young people

Rendering of a brain.
Researchers show for the first time that healthy older men and women can generate just as many new brain cells as younger people.

There has been controversy over whether adult humans grow new neurons, and some research has previously suggested that the adult brain was hard-wired and that adults did not grow new neurons. This study, to appear in the journal Cell Stem Cell on April 5, counters that notion. Lead author Maura Boldrini, associate professor of neurobiology at Columbia University, says the findings may suggest that many senior citizens remain more cognitively and emotionally intact than commonly believed.

"We found that older people have similar ability to make thousands of hippocampal new neurons from progenitor cells as younger people do," Boldrini says. "We also found equivalent volumes of the hippocampus (a brain structure used for emotion and cognition) across ages. Nevertheless, older individuals had less vascularization and maybe less ability of new neurons to make connections."

The researchers autopsied hippocampi from 28 previously healthy individuals aged 14-79 who had died suddenly. This is the first time researchers looked at newly formed neurons and the state of blood vessels within the entire human hippocampus soon after death. (The researchers had determined that study subjects were not cognitively impaired and had not suffered from depression or taken antidepressants, which Boldrini and colleagues had previously found could impact the production of new brain cells.)

In rodents and primates, the ability to generate new hippocampal cells declines with age. Waning production of neurons and an overall shrinking of the dentate gyrus, part of the hippocampus thought to help form new episodic memories, was believed to occur in aging humans as well.

The researchers from Columbia University and New York State Psychiatric Institute found that even the oldest brains they studied produced new brain cells. "We found similar numbers of intermediate neural progenitors and thousands of immature neurons," they wrote. Nevertheless, older individuals form fewer new blood vessels within brain structures and possess a smaller pool of progenitor cells -- descendants of stem cells that are more constrained in their capacity to differentiate and self-renew.

Boldrini surmised that reduced cognitive-emotional resilience in old age may be caused by this smaller pool of neural stem cells, the decline in vascularization, and reduced cell-to-cell connectivity within the hippocampus. "It is possible that ongoing hippocampal neurogenesis sustains human-specific cognitive function throughout life and that declines may be linked to compromised cognitive-emotional resilience," she says.

Read more at Science Daily

How birds can detect Earth’s magnetic field

Zebra finches.
Researchers at Lund University in Sweden have made a key discovery about the internal magnetic compass of birds. Biologists have identified a single protein without which birds probably would not be able to orient themselves using the Earth's magnetic field.

The receptors that sense the Earth's magnetic field are probably located in the birds' eyes. Now, researchers at Lund University have studied different proteins in the eyes of zebra finches and discovered that one of them differs from the others: only the Cry4 protein maintains a constant level throughout the day and in different lighting conditions.

Cry4 belongs to a group of proteins called cryptochromes. Normally they regulate the biological clock, but have also been considered significant for the magnetic sense. With this study, we now know which of the birds' cryptochromes do what.

"Cry4 is an ideal magnetoreceptor as the level of the protein in the eyes is constant. This is something we expect from a receptor that is used regardless of the time of day," explains Atticus Pinzón-Rodríguez, one of the researchers behind the study.

The conclusion is thus that this specific protein helps the magnetic sense to function, while other cryptochromes, whose levels in the body vary at different times of the day, take care of the biological clock instead.

Last year, Atticus Pinzón-Rodríguez and his colleagues noted that not only migratory birds navigate using a magnetic compass. Even resident birds that do not migrate in the spring and autumn have a magnetic sense and navigate using their internal magnetic compass. He now takes this one step further:

"This and last year's results indicate that other animals, perhaps all of them, have magnetic receptors and can pick up on magnetic fields."

Read more at Science Daily

New source of global nitrogen discovered

The Pinnacles of Gunung Mulu in Borneo are an example of where limestone rock weathering would be expected to produce significant levels of nitrogen.
For centuries, the prevailing science has indicated that all of the nitrogen on Earth available to plants comes from the atmosphere. But a study from the University of California, Davis, indicates that more than a quarter comes from Earth's bedrock.

The study, to be published April 6 in the journal Science, found that up to 26 percent of the nitrogen in natural ecosystems is sourced from rocks, with the remaining fraction from the atmosphere.

Before this study, the input of this nitrogen to the global land system was unknown. The discovery could greatly improve climate change projections, which rely on understanding the carbon cycle. This newly identified source of nitrogen could also feed the carbon cycle on land, allowing ecosystems to pull more emissions out of the atmosphere, the authors said.

"Our study shows that nitrogen weathering is a globally significant source of nutrition to soils and ecosystems worldwide," said co-lead author Ben Houlton, a professor in the UC Davis Department of Land, Air and Water Resources and director of the UC Davis Muir Institute. "This runs counter the centuries-long paradigm that has laid the foundation for the environmental sciences. We think that this nitrogen may allow forests and grasslands to sequester more fossil fuel CO2 emissions than previously thought."

Weathering Is Key

Ecosystems need nitrogen and other nutrients to absorb carbon dioxide pollution, and there is a limited amount of it available from plants and soils. If a large amount of nitrogen comes from rocks, it helps explain how natural ecosystems like boreal forests are capable of taking up high levels of carbon dioxide.

But not just any rock can leach nitrogen. Rock nitrogen availability is determined by weathering, which can be physical, such as through tectonic movement, or chemical, such as when minerals react with rainwater.

That's primarily why rock nitrogen weathering varies across regions and landscapes. The study said that large areas of Africa are devoid of nitrogen-rich bedrock while northern latitudes have some of the highest levels of rock nitrogen weathering. Mountainous regions like the Himalayas and Andes are estimated to be significant sources of rock nitrogen weathering, similar to those regions' importance to global weathering rates and climate. Grasslands, tundra, deserts and woodlands also experience sizable rates of rock nitrogen weathering.

Geology and Carbon Sequestration

Mapping nutrient profiles in rocks to their potential for carbon uptake could help drive conservation considerations. Areas with higher levels of rock nitrogen weathering may be able to sequester more carbon.

"Geology might have a huge control over which systems can take up carbon dioxide and which ones don't," Houlton said. "When thinking about carbon sequestration, the geology of the planet can help guide our decisions about what we're conserving."

Mysterious Gap

The work also elucidates the "case of the missing nitrogen." For decades, scientists have recognized that more nitrogen accumulates in soils and plants than can be explained by the atmosphere alone, but they could not pinpoint what was missing.

"We show that the paradox of nitrogen is written in stone," said co-leading author Scott Morford, a UC Davis graduate student at the time of the study. "There's enough nitrogen in the rocks, and it breaks down fast enough to explain the cases where there has been this mysterious gap."

In previous work, the research team analyzed samples of ancient rock collected from the Klamath Mountains of Northern California to find that the rocks and surrounding trees there held large amounts of nitrogen. With the current study, the authors built on that work, analyzing the planet's nitrogen balance, geochemical proxies and building a spatial nitrogen weathering model to assess rock nitrogen availability on a global scale.

The researchers say the work does not hold immediate implications for farmers and gardeners, who greatly rely on nitrogen in natural and synthetic forms to grow food. Past work has indicated that some background nitrate in groundwater can be traced back to rock sources, but further research is needed to better understand how much.

Rewriting Textbooks

"These results are going to require rewriting the textbooks," said Kendra McLauchlan, program director in the National Science Foundation's Division of Environmental Biology, which co-funded the research. "While there were hints that plants could use rock-derived nitrogen, this discovery shatters the paradigm that the ultimate source of available nitrogen is the atmosphere. Nitrogen is both the most important limiting nutrient on Earth and a dangerous pollutant, so it is important to understand the natural controls on its supply and demand. Humanity currently depends on atmospheric nitrogen to produce enough fertilizer to maintain world food supply. A discovery of this magnitude will open up a new era of research on this essential nutrient."

Read more at Science Daily

Apr 5, 2018

Diving deep into the blue whale genome reveals the animals’ extraordinary evolutionary history

Blue Whale underwater.
For the first time, scientists of the German Senckenberg Biodiversity and Climate Research Center, Goethe University and the University of Lund in Sweden have deciphered the complete genome of the blue whale and three other rorquals. These insights now allow tracking the evolutionary history of the worlds’ largest animal and its relatives in unprecedented detail. Surprisingly, the genomes show that rorquals have been hybridizing during their evolutionary history. In addition, rorquals seem to have separated into different species in the absence of geographical barriers. This phenomenon, called sympatric speciation, is very rare in animals. The study has just been published in Science Advances.

Blue whales are the giants of the sea. With up to 30 meters (100 feet) long and weighing up to 175 tons, they are the largest animals that ever evolved on earth; larger even than dinosaurs. Short of becoming extinct due to whaling by the end of the 80s, currently the populations of the gentle giants are slowly recovering. Now new research highlights that the evolution of these extraordinary animals and other rorquals was also anything but ordinary.

A research team led by Professor Axel Janke, evolutionary geneticist at the Senckenberg Biodiversity and Climate Research Center and Goethe University, has found that the rorquals, including the blue whale, mated across emerging species boundaries. “Speciation under gene flow is rare. Usually, species are assumed to be reproductively isolated because geographical or genetic barriers inhibits genetic exchange. Apparently however, this does not apply to whales”, explains Fritjof Lammers, co-lead-author of the study, Senckenberg Biodiversity and Climate Research Centre.

Teaming up with cetacean specialist Professor Ulfur Arnason at University of Lund, Sweden, Lammers and his colleagues are the first to have sequenced the complete genome of the blue whale and other rorquals, including the humpback and the gray whale. For these migratory whales, geographical barriers do not exist in the vastness of the ocean, instead some rorquals differentiated by inhabiting different ecological niches.  Cross-genome analyses now indicate that there are apparently no genetic barriers between species and that there has been gene flow among different rorqual species in the past.

This is confirmed by spotting hybrids between fin and blue whales still to date, which have been witnessed and genetically studied by Professor Arnason. However, the researchers could not detect traces of recent liaisons between the two species in their genomes. This is probably because whale genomes are currently known only from one or two individuals.

To track down the rorquals’ evolution, the scientists have applied so-called evolutionary network analyses. "In these analyses, speciation is not considered as a bifurcating phylogenetic tree as Darwin has envisioned it, but as an interwoven network. This allows us to discover hidden genetic signals, that otherwise would have stayed undetected", says Janke.

Overall, the research also shows that the relationships among the rorqual species are more complicated than hitherto thought. So far, the humpback whale has been seen as an outsider among the rorquals because of its enormous fins. The genome reveals that this classification does match the evolutionary signals. The same is true for the gray whale, which was believed to be evolutionarily distinct from rorquals due to its appearance. Genomic analyses show however that gray whales are nested within rorquals. Gray whales just happened to occupy a new ecological niche by feeding on crustaceans in coastal oceanic waters.

Read more at Science Daily

Bonobos share and share alike

African breadfruit (Treculia africana) sharing: a party is gathered around the owner (in this case, a male).
Bonobos are willing to share meat with animals outside their own family groups. This behaviour was observed in the Democratic Republic of the Congo and is documented in a new study in Springer's journal Human Nature. Even though bonobo apes have been studied for years, animal behaviourists have only realised in the past 25 years that these primates do not only eat plants, but similar to the common chimpanzee, also hunt and share their catch among members of their own social group. This study is the first observation of sharing behaviour across community borders and was led by Barbara Fruth of Liverpool John Moores University in the UK and the Royal Zoological Society of Antwerp in Belgium, and Gottfried Hohmann of the Max-Planck-Institute for Evolutionary Anthropology in Germany.

Fruth and Hohmann's team witnessed the behaviour in January 2017 while studying two neighboring communities of bonobos (Pan paniscus) in a forest area near the Bompusa River. Researchers have previously noted that these communities hunt or eat meat twice a month on average. In most cases they opportunistically kill a small forest antelope called a duiker.

One afternoon, bonobos from the Bompusa West community met up with the Bompusa East bonobo community. After the alpha male of the West party caught a duiker, he was immediately approached by members of both communities. He moved into the crown of a tall tree, followed by nine females (four from the one group, five from the other) and their offspring. For the next half an hour, the researchers watched how he dished out some meat to all of them.

"Solicitation involved behaviours such as peering and stretched out hands but no aggression or forceful taking. As in other cases, the transfer of food from the male to females was passive," remembers Fruth, who says that the pieces of meat given were immediately eaten.

One of the females from the East party then removed the duiker's entire head to share pieces of meat with her offspring and adult females from both communities. A female from the West party only shared a leg from the carcass with her offspring and other female members of her party. Only the initial male participated in the meat-sharing episode, despite seven others being present.

The social structure of bonobos is dominated by females, and sex plays a major part in keeping the peace within a group. During the course of the meat-feeding period, the researchers also observed how females (even ones from different groups) rubbed their genitals together. A male mated with a female from an opposing community, while grooming between members of the different groupings also took place.

"No aggression was observed among females, between males and females, or among males, a behaviour not uncommon during other inter-community encounters," notes Fruth.

Read more at Science Daily

Astrophysicists map the infant universe in 3-D and discover 4,000 early galaxies

This is a map of the cube of spacetime covered in the new survey, showing the distance to the galaxies in billions of light years. The positions of the 4,000 galaxies appear as circles. The colours represent the degree of redshift seen, with the bluer circles indicating galaxies nearer to the Earth, and so less redshifted. Green, yellow, orange and red circles indicate successively higher redshifts, and galaxies that are progressively further away from the Earth.
Astronomers today announce one of the largest 3D maps of the infant Universe, in a presentation at the European Week of Astronomy and Space Science in Liverpool. A team led by Dr David Sobral of Lancaster University made the chart using the Subaru telescope in Hawaii and the Isaac Newton telescope in the Canary Islands. Looking back in time to 16 different epochs between 11 and 13 billion years ago, the researchers discovered almost 4000 early galaxies, many of which will have evolved into galaxies like our own Milky Way.

Light from the most distant galaxies takes billions of years to reach us. This means that telescopes act as time machines, allowing astronomers to see galaxies in the distant past. The light from these galaxies is also stretched by the expansion of the Universe, increasing its wavelength to make it redder. This so-called redshift is related to the distance of the galaxy. By measuring the redshift of a galaxy, astronomers can thus deduce its distance, how long its light has taken to reach us and hence how far back in time we are seeing it.

In the new work the team used filters to sample particular wavelengths of light, and hence specific epochs in the history of the Universe.

Sergio Santos, a Lancaster PhD student and team member, comments: "We used large amounts of data taken with 16 special filters on wide field cameras and processed them here in Lancaster to literally slice the Universe in cosmic time and time-travel to the distant past with 16 well defined cosmic time destinations."

Dr Sobral adds: "These early galaxies seem to have gone through many more "bursts" when they formed stars, instead of forming them at a relatively steady rate like our own galaxy. Additionally, they seem to have a population of young stars that is hotter, bluer and more metal-poor than those we see today."

Sobral and his team found galaxies that existed when the Universe was only 20 to 7% of its current age, and hence provide crucial information about the early phases of galaxy formation.

The researchers also found that these early galaxies are incredibly compact. "The bulk of the distant galaxies we found are only about 3 thousand light years across in size, while our Milky Way is about 30 times larger. Their compactness likely explains many of their exciting physical properties that were common in the early Universe," comments Ana Paulino-Afonso, a PhD student in Lancaster and Lisbon. "Some of these galaxies should have evolved to become like our own and thus we are seeing what our galaxy may have looked like 11 to 13 billion years ago."

Read more at Science Daily

Prehistoric reptile pregnant with octuplets

Image of pregnant ichthyosaur with octuplets.
Palaeontologists have discovered part of the skeleton of a 180 million-year-old pregnant ichthyosaur with the remains of between six and eight tiny embryos between its ribs.

The new specimen was studied by palaeontologists Mike Boyd and Dean Lomax from The University of Manchester. It was collected around 2010 from near Whitby, North Yorkshire and is from the Early Jurassic. The fossil was in the collection of fossil collector, Martin Rigby, who thought the specimen might be a block of embryos. Dean confirmed the suspicion and the specimen was acquired by the Yorkshire Museum, York.

Ichthyosaurs were aquatic reptiles that dominated the Jurassic seas. They gave birth to live young, rather than laying eggs, and did not need to return to land, even to breed. They were carnivores, feeding upon other reptiles, fish, and marine invertebrates such as the squid-like belemnites.

Ichthyosaur fossils are quite common in the UK and often found in British Jurassic rocks. However, only five ichthyosaur specimens from Britain have ever been found with embryos and none with this many. All five were collected from Jurassic exposures in the south-west of England and are between 200-190 million years old. This is the first to be found in Yorkshire. The new specimen is a star attraction in the new major exhibition, Yorkshire's Jurassic World, which recently opened on March 24.

The Jurassic rocks of Yorkshire have produced hundreds of ichthyosaur and other marine reptile skeletons, but have not, until now, yielded any reptilian embryos. The new specimen, as well as being the first embryo-bearing ichthyosaur recorded from Yorkshire, is also geologically the youngest of the British embryo-bearing specimens, being from the Toarcian Stage of the Jurassic, around 180 million-year-old.

The specimen is a small boulder that has been cut in half and polished, which exposes several large ribs (of the adult) and several strings of vertebrae and various indeterminate tiny bones. Boyd and Lomax say there are at least six embryos present, but probably eight.

Mike said: "We also considered the possibility that the tiny remains could be stomach contents, although it seemed highly unlikely that an ichthyosaur would swallow six to eight aborted embryos or newborn ichthyosaurs at one time. And this does not seem to have been the case, because the embryos display no erosion from stomach acids. Moreover, the embryos are not associated with any stomach contents commonly seem in Early Jurassic ichthyosaurs, such as the remains of squid-like belemnites."

Eight different species of ichthyosaur have been documented with embryos. By far, the most commonly found ichthyosaur with embryos is Stenopterygius. Over a hundred specimens of Stenopterygius from Holzmaden and surrounding areas in Germany have been found with embryos, ranging from one to eleven in number.

"The German sites are approximately the same age as the new specimen from Whitby and it is possible that the new specimen is also Stenopterygius, but no identifiable features are preserved in the adult or embryos. Nonetheless, this is an important find." added Dean.

Read more at Science Daily

Apr 4, 2018

Rare Scottish dinosaur prints give key insight into era lost in time

A series of rare dinosaur footprints discovered on the Isle of Skye, including this one made by a two-meter high theropod, is helping experts establish details of an important period in dinosaur evolution.
Dozens of giant footprints discovered on a Scottish island are helping shed light on an important period in dinosaur evolution.

The tracks were made some 170 million years ago, in a muddy, shallow lagoon in what is now the north-east coast of the Isle of Skye.

Most of the prints were made by long-necked sauropods -- which stood up to two metres tall -- and by similarly sized theropods, which were the older cousins of Tyrannosaurus rex.

The find is globally important as it is rare evidence of the Middle Jurassic period, from which few fossil sites have been found around the world.

Researchers measured, photographed and analysed about 50 footprints in a tidal area at Brothers' Point -- Rubha nam Brathairean -- a dramatic headland on Skye's Trotternish peninsula.

The footprints were difficult to study owing to tidal conditions, the impact of weathering and changes to the landscape. In spite of this, scientists identified two trackways in addition to many isolated foot prints.

Researchers used drone photographs to make a map of the site. Additional images were collected using a paired set of cameras and tailored software to help model the prints.

Analysis of the clearest prints -- including the overall shape of the track outline, the shape and orientation of the toes, and the presence of claws -- enabled scientists to ascribe them to sauropods and theropods.

The study, carried out by the University of Edinburgh, Staffin Museum and Chinese Academy of Sciences, was published in the Scottish Journal of Geology. It was supported by a grant from the National Geographic Society, and subsidiary funding from the Association of Women Geologists, Derek and Maureen Moss, Edinburgh Zoo and Edinburgh Geological Society.

Paige dePolo, who led the study, conducted the research while an inaugural student in the University's Research Master's degree programme in palaeontology and geobiology.

Ms dePolo said: "This tracksite is the second discovery of sauropod footprints on Skye. It was found in rocks that were slightly older than those previously found at Duntulm on the island and demonstrates the presence of sauropods in this part of the world through a longer timescale than previously known. This site is a useful building block for us to continue fleshing out a picture of what dinosaurs were like on Skye in the Middle Jurassic."

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Great magma erup­tions had two sources

Lava layers of the Karoo magma province are found at the Victoria Falls, Africa.
Research at Finnish Museum of Natural History may explain controversies related to great magma eruptions.

The modern continents were formed when Pangea broke into pieces in the Mesozoic time. The splitting of Africa from Antarctica started with great magma eruptions that flooded over an area millions of square kilometres wide.

Remnants of the ancient ocean of lava, the so-called Karoo magma province, are still widespread in southern Africa and have been also discovered in Antarctica. Dr Arto Luttinen from the Finnish Museum of Natural History, University of Helsinki, has studied the lava formations on both continents with his group.

"This kind of eruptions are culmination events of planetary evolution and have caused mass extinctions of life. Yet their origin remains an outstanding question of Earth history" Luttinen explains.

The scientists disagree, for example, whether an enormous ascending plume of hot material caused the generation of magmas from the core-mantle boundary.

"Previous geophysical research has indicated features suggestive of mantle plumes, whereas geochemical studies have concluded based on lava compositions that there was no plume and that the magmas formed when the temperature of the upper mantle gradually got higher under Pangea. The supercontinent acted like a kettle lid" Luttinen summarises.

The previous studies of magma sources have mainly focused on a certain part of the widespread lava formation, however. The study published on March 27 in the international journal Scientific Reports scrutinised compositions of lava samples across the whole region of ancient magma eruptions. Their chemical signatures indicate that lavas in different areas had a different origin.

"The magmas had in fact two contrasting sources. One of them was the upper mantle, as suggested in previous research, whereas the other was most probably a deep mantle plume. Involvement of two different magma sources explains previous contradictory results and presents an interesting new framework for future studies," concludes Luttinen.

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Ancient origins of viruses discovered

Rendering of viruses. A new study transforms our understanding of virus origins and evolution.
Research published today in Nature has found that many of the viruses infecting us today have ancient evolutionary histories that date back to the first vertebrates and perhaps the first animals in existence.

The study, a collaboration between the University of Sydney, the China Center for Disease Control and Prevention and the Shanghai Public Health Clinical Centre, looked for RNA viruses in 186 vertebrate species previously ignored when it came to viral infections.

The researchers discovered 214 novel RNA viruses (where the genomic material is RNA rather than DNA) in apparently healthy reptiles, amphibians, lungfish, ray-finned fish, cartilaginous fish and jawless fish.

"This study reveals some groups of virus have been in existence for the entire evolutionary history of the vertebrates -- it transforms our understanding of virus evolution," said Professor Eddie Holmes, of the Marie Bashir Institute for Infectious Diseases & Biosecurity at the University of Sydney.

"For the first time we can definitely show that RNA viruses are many millions of years old, and have been in existence since the first vertebrates existed.

"Fish, in particular, carry an amazing diversity of viruses, and virtually every type of virus family detected in mammals is now found in fish. We even found relatives of both Ebola and influenza viruses in fish."

However, Professor Holmes was also quick to emphasise that these fish viruses do not pose a risk to human health and should be viewed as a natural part of virus biodiversity.

"This study emphasises just how big the universe of viruses -- the virosphere -- really is. Viruses are everywhere.

"It is clear that there are still many millions more viruses still to be discovered," he said.

The newly discovered viruses appeared in every family or genus of RNA virus associated with vertebrate infection, including those containing human pathogens such as influenza virus.

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Tens of thousands of black holes may exist in Milky Way's center

Artist's concept of black hole.
A Columbia University-led team of astrophysicists has discovered a dozen black holes gathered around Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way Galaxy. The finding is the first to support a decades-old prediction, opening up myriad opportunities to better understand the universe.

"Everything you'd ever want to learn about the way big black holes interact with little black holes, you can learn by studying this distribution," said Columbia Astrophysicist Chuck Hailey, co-director of the Columbia Astrophysics Lab and lead author on the study. "The Milky Way is really the only galaxy we have where we can study how supermassive black holes interact with little ones because we simply can't see their interactions in other galaxies. In a sense, this is the only laboratory we have to study this phenomenon."

The study appears in the April 5 issue of Nature.

For more than two decades, researchers have searched unsuccessfully for evidence to support a theory that thousands of black holes surround supermassive black holes (SMBHs) at the center of large galaxies.

"There are only about five dozen known black holes in the entire galaxy -- 100,000 light years wide -- and there are supposed to be 10,000 to 20,000 of these things in a region just six light years wide that no one has been able to find," Hailey said, adding that extensive fruitless searches have been made for black holes around Sgr A*, the closest SMBH to Earth and therefore the easiest to study. "There hasn't been much credible evidence."

He explained that Sgr A* is surrounded by a halo of gas and dust that provides the perfect breeding ground for the birth of massive stars, which live, die and could turn into black holes there. Additionally, black holes from outside the halo are believed to fall under the influence of the SMBH as they lose their energy, causing them to be pulled into the vicinity of the SMBH, where they are held captive by its force.

While most of the trapped black holes remain isolated, some capture and bind to a passing star, forming a stellar binary. Researchers believe there is a heavy concentration of these isolated and mated black holes in the Galactic Center, forming a density cusp which gets more crowded as distance to the SMBH decreases.

In the past, failed attempts to find evidence of such a cusp have focused on looking for the bright burst of X-ray glow that sometimes occurs in black hole binaries

"It's an obvious way to want to look for black holes," Hailey said, "but the Galactic Center is so far away from Earth that those bursts are only strong and bright enough to see about once every 100 to 1,000 years." To detect black hole binaries then, Hailey and his colleagues realized they would need to look for the fainter, but steadier X-rays emitted when the binaries are in an inactive state.

"It would be so easy if black hole binaries routinely gave off big bursts like neutron star binaries do, but they don't, so we had to come up with another way to look for them," Hailey said. "Isolated, unmated black holes are just black -- they don't do anything. So looking for isolated black holes is not a smart way to find them either. But when black holes mate with a low mass star, the marriage emits X-ray bursts that are weaker, but consistent and detectable. If we could find black holes that are coupled with low mass stars and we know what fraction of black holes will mate with low mass stars, we could scientifically infer the population of isolated black holes out there."

Hailey and colleagues turned to archival data from the Chandra X-ray Observatory to test their technique. They searched for X-ray signatures of black hole-low mass binaries in their inactive state and were able to find 12 within three light years, of Sgr A*. The researchers then analyzed the properties and spatial distribution of the identified binary systems and extrapolated from their observations that there must be anywhere from 300 to 500 black hole-low mass binaries and about 10,000 isolated black holes in the area surrounding Sgr A*.

"This finding confirms a major theory and the implications are many," Hailey said. "It is going to significantly advance gravitational wave research because knowing the number of black holes in the center of a typical galaxy can help in better predicting how many gravitational wave events may be associated with them. All the information astrophysicists need is at the center of the galaxy."

Read more at Science Daily

Apr 3, 2018

Oldest Neanderthal wooden tools found in Spain

Neanderthal wooden tools.
Archaeological excavations at Aranbaltza site in the Basque Country coast (Northern Spain), have revealed several episodes of Neanderthal occupations with preserved wooden remains. The fieldwork is leaded by Joseba Rios-Garaizar, archaeologist from the Spanish Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). In 2015, the excavation revealed two very well preserved wooden tools; one of them is a 15 cm long digging stick.

The detailed analysis of this tool and the Luminescence dating of the sediment that bares the wooden remains indicate that the objects were deposited around 90,000 years and thus, they were made by Neanderthals.

The Micro-CT analysis and a close examination of the surface developed at CENIEH laboratories have shown that a yew trunk was cut longitudinally into two halves. One of this halves was scraped with a stone-tool, and treated with fire to harden it and to facilitate the scraping to obtain a pointed morphology. Use-wear analysis revealed that it was used for digging in search of food, flint, or simply to make holes in the ground.

The preservation of wooden tools associated to Neanderthals is very rare because wood degrades very quickly. Only in very specific environments, like the waterlogged sediments from Aranbaltza, it has been possible to find evidence of wooden technology. As it was suggested by indirect evidence, this type of technology was relevant in Neanderthal daily life.

In the Iberian Peninsula wooden tools associated to Neanderthals have been found only in the travertine from Abric Romaní (Catalonia), and in the rest of Europe only four sites (Clacton on Sea, Schöningen, Lehringen and Poggeti Vechi) have provided wooden tools associated to Neanderthals or pre-Neanderthals. Therefore, findings like the one from Aranbaltza are crucial to investigate the Neanderthal technology and use of wood.

The archaeological project at Aranbaltza started in 2013 to investigate the last Neanderthals from Western Europe, who were responsible of the Chatelperronian culture. The ongoing excavations have revealed different Neanderthal occupation events spanning from 100 to 44,000 years. This makes of Aranbaltza an exceptional site to investigate Neanderthal evolution and behavioral variability.

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First age-map of the heart of the Milky Way

This is an artist's impression showing the peanut shaped structure in the central bulge.
The first large-scale age-map of the Milky Way shows that a period of star formation lasting around 4 billion years created the complex structure at the heart of our galaxy. The results will be presented by Marina Rejkuba at the European Week of Astronomy and Space Science (EWASS) in Liverpool on Tuesday, 3rd April.

The Milky Way is a spiral galaxy with a bulge at the centre, thousands of light years in diameter, that contains about a quarter of the total mass of stars. Previous studies have shown that the bulge hosts two components: a population of metal-poor stars that have a spherical distribution, and a population of metal-rich stars that form an elongated bar with a "waist," like an x or a bi-lobed peanut. However, analyses of the ages of the stars to date have produced conflicting results. Now, an international team led by astronomers from the European Southern Observatory (ESO) have analysed the colour, brightness and spectral information on chemistry of individual stars to produce the age-map of the Milky Way.

The team have used simulated and observed data for millions of stars from the VISTA Variables in the Via Lactea (VVV) infrared survey of the inner Milky Way and compared them with measurements of the metal content of around 6000 stars across the inner bulge from a spectroscopic survey carried out with the GIRAFFE/FLAMES spectrograph on the ESO Very Large Telescope (GIBS).

Rejkuba says: "We analysed the colour and brightness of stars to find those that have just reached the point of exhausting their hydrogen fuel-burning in the core, which is a sensitive age indicator. Our findings were not consistent with a purely old Milky Way bulge, but require star formation lasting around 4 billion years and starting around 11 billion years ago. The youngest stars that we see are at least 7 billion years old, which is older than some previous studies had suggested."

The results presented are based on the analysis of three areas of the VVV infrared map, which, combined, make up the largest area studied so far in the Milky Way bulge. In all three areas, the findings on the age range of the stars are consistent.

Francisco Surot Madrid, the co-lead author of the study, says: "Previous studies have told us that the metal-rich stars in the bar are likely to be the youngest stars. Whilst we can't disentangle which star belongs to the bar/peanut or the spheroid component in the data we are using, our results tell us that the bar was already formed about 7 billion years ago and there were no large amounts of gas inflowing and forming stars along the bar after that."

The ultimate goal of this project is the construction of a map of the star formation history of the entire Milky Way bulge.

Read more at Science Daily

Earth's stable temperature past suggests other planets could also sustain life

The study significantly narrows the possible temperature of the early Earth to 0 to 50 degrees Celsius. It also finds the ocean's pH has remained fairly moderate, gradually increasing from a slightly acidic initial value of about 6.6, through the neutral value of 7.0, to today's slightly alkaline seawater of about 8.1.
Theories about the early days of our planet's history vary wildly. Some studies have painted the picture of a snowball Earth, when much of its surface was frozen. Other theories have included periods that would be inhospitably hot for most current lifeforms to survive.

New research from the University of Washington suggests a milder youth for our planet. An analysis of temperature through early Earth's history, published the week of April 2 in the Proceedings of the National Academy of Sciences, supports more moderate average temperatures throughout the billions of years when life slowly emerged on Earth.

"Ideas about the early Earth's environment are all over the place, from a very hot world, to one locked in a permanent ice age, from a world with acidic oceans to one with seawater so alkaline it would sting your eyes," said David Catling, a UW professor of Earth and space sciences. "These simulations show that our early world had about the same average temperature as today, and a seawater pH within roughly one unit of neutral."

Previous research studies have put average temperatures during the Archean era, 4 to 2.5 billion years ago, as low as minus 25 degrees Celsius. Other estimates, based on different interpretations of the evidence, have placed average temperatures as high as 85 degrees Celsius, under which only heat-loving microbes that now exist in hot springs could survive.

The new results put the outer range of possible temperatures at 0 to 50 C (32 to 122 F).

"Our results show that Earth has had a moderate temperature through virtually all of its history, and that is attributable to weathering feedbacks -- they do a good job at maintaining a habitable climate," said first author Joshua Krissansen-Totton, a UW doctoral student in Earth and space sciences.

To create their estimate, the researchers took the most recent understanding for how rocks, oceans, and air temperature interact, and put that into a computer simulation of Earth's temperature over the past 4 billion years. Their calculations included the most recent information for how seafloor weathering occurs on geologic timescales, and under different conditions.

Though we don't think of wind and rain wearing away at the seafloor, the seabed is eroded as seawater percolates through rock on the ocean's floor. Carbon-containing molecules settle out from the water, a process related to the temperature and acidity of the seawater, while other chemicals are dissolved from the rock.

"Seafloor weathering was more important for regulating temperature of the early Earth because there was less continental landmass at that time, the Earth's interior was even hotter, and the seafloor crust was spreading faster, so that was providing more crust to be weathered," Krissansen-Totton said.

The authors ran simulations for many possible scenarios for the size of the continents, the temperature sensitivity of chemical weathering and other factors to get the full range of possible scenarios for average air temperature and ocean pH through history.

"We got this initial answer that early Earth had moderate temperatures and slightly acidic ocean pH," Krissansen-Totton said. "I tried really hard to break that, looking for assumptions that could possibly change that answer. But I found that this is a really robust result. It's hard to imagine a realistic scenario where temperatures or pH were more extreme."

That is good news for the search for life on other planets. If Earth's temperature was pretty moderate throughout its history, other planets located in the habitable zone must also retain a fairly stable climate long enough for other lifeforms to evolve.

"There's nothing particularly remarkable about these processes," Krissansen-Totton said. "They can occur on any rocky planet with oceans. So other planets that are in the habitable zone are likely to have their climates stabilized to moderate values by these weathering feedbacks. And that's a good thing for the search for life, because you need moderate temperatures for billions of years to have a stable environment for life to evolve."

Read more at Science Daily

Spear point study offers new explanation of how early humans settled North America

Spear points with fluted edges prove that early inhabitants traveled all over North America.
Careful examination of numerous fluted spear points found in Alaska and western Canada prove that the Ice Age peopling of the Americas was much more complex than previously believed, according to a study done by two Texas A&M University researchers.

Heather Smith and Ted Goebel both were involved with the study that was associated with the Center for the Study of the First Americans, part of the Department of Anthropology at Texas A&M. Smith is now an assistant professor at Eastern New Mexico University.

Their work has been published in the current issue of PNAS (Proceedings of the National Academy of Sciences).

Smith, who worked on the study as part of her Ph.D. at Texas A&M, and Goebel, professor of anthropology at Texas A&M, believe the findings could change how we view the traveling patterns and routes of early humans from 14,000 to 12,000 years ago as they settled in numerous parts of North America.

Using new digital methods of analyses utilized for the first time in such a study of these artifacts, the researchers found that early settlers in the emerging ice-free corridor of interior western Canada "were travelling north to Alaska, not south from Alaska, as previously interpreted," says Goebel.

"Although during the late Ice Age there were two possible routes for the first Americans to follow on their migration from the Bering Land Bridge area southward to temperate North America, it now looks like only the Pacific coastal route was used, while the interior Canadian route may not have been fully explored until millennia later, and when it was, primarily from the south.

"The findings of these fluted spear points provide archaeological evidence supporting new genetic models explaining how humans colonized the New World."

Traditional interpretations of the peopling of the Americas have predicted that early inhabitants migrated from Siberia through Alaska, and then followed the ice-free corridor that gradually opened in western Canada to reach the Great Plains of the western U.S. But newer genetic studies of ancient Siberians, Alaskans, and Americans, as well as the discovery of new sites south of the Canadian ice sheets predating the opening of the ice-free corridor, suggest instead that the first Americans passed along the Pacific coast.

"The key is that the projectile points are related in their technology and morphology, and the way in which some of these characteristics vary forms the pattern of an ancestral-descendent relationship. This suggests that the people who carried the artifacts to these locations were related as well." adds Smith.

"It shows that these early people in western Canada and Alaska were descendent of Clovis (the first settlers of North America) and they used the same type of weapons to hunt for food, especially bison. These makers of fluted points were not just all over mid-continent North America but were also migrating northward back to the Arctic."

These artifacts can be used to document migration patterns of prehistoric peoples, she says.

"The spear points prove that the peopling of the Americas was much more complex than we had believed and that these early settlers went in a lot of different directions, not just south. We now have a better picture of what weapons they used to hunt and where their travels took them."

Read more at Science Daily

This Extinct Monitor Lizard Had Four Eyes

Fossil of Saniwa ensidens in the Field Museum of Natural History
Nearly all animals have two eyes, but there are rare exceptions. Crustaceans in the appropriately named family Cyclopidae, aka Cyclops, for example, see their world through a single large eye. On the other side of the spectrum are giant clams, which have hundreds of eyes. Among vertebrates, the record holder is the jawless lamprey. Part of a very ancient lineage, this eel-resembling fish possesses four eyes.

The extra two eyes are photosensory structures at the top of the head known as the pineal and parapineal organs. Scientists are still trying to determine all of the functions of these organs, but it is known that they play key roles in orientation and in circadian and annual cycles.

The pineal organ is found in a number of lower vertebrates, such as fishes and frogs, but the parapineal organ is less common. Krister Smith of the Senckenberg Research Institute, however, has long suspected that ancient lizards might have had both of the photosensory structures along with two more typical eyes.

"The idea first germinated when, as a graduate student, I was surveying the diversity of fossil lizards in the Yale collections," Smith said. "In one case, there were contradictory interpretations of the third eye in the parietal bone by different experts. It was clear that there were two large holes in the bone, one behind the other, and I recalled that there were two pineal organs."

Smith admits that it was a "wacky" idea to search for an ancient lizard with four eyes, but she and her team did just that.

They scoured museum specimens collected nearly 150 years ago at Grizzly Buttes, a site in the Bridger Basin of Wyoming. CT scans revealed that two different individuals from an extinct species of monitor lizard (Saniwa ensidens) had spaces where the extra two eyes would have been.

The discovery, reported in the journal Current Biology, documents the first known four-eyed jawed vertebrate.

"As a scientist, one has lots of ideas, but many — even most of them — don't pan out, and the more idiosyncratic an idea is, the more likely it is to fail," Smith said, adding that she was thrilled when her suspicions about fossilized lizards proved to be correct.

The discovery sheds light on the evolution of the extra eyes.

This image depicts a reconstruction of what the extinct monitor lizard might have looked like. The parietal and pineal foramina are visible on the overlaid skull.
Smith and her colleagues Bhart-Anjan Bhullar, Gunther Köhler, and Jörg Habersetzer suspect that lampreys evolved their four eyes simultaneously, but they say that more fossil finds will be needed to determine when each of the organs emerged.

What is known is that the earliest mammals — our distant ancestors — did not just have two eyes.

"Stem mammals had three eyes," Smith explained. "It has been proposed that the nocturnal phase of evolution in mammalian ancestors led to the disappearance of the third eye in that lineage, and perhaps something similar happened in other tetrapod groups."

Many tetrapods, or four-footed animals, therefore might have lost their third eye when some became active at night and presumably didn't need the additional photosensory organs.

Humans and most other mammals retain no lingering evidence of a third eye.

"In particular in humans, the cerebrum is so massively expanded that it thickly and completely covers the pineal organ, making it virtually impossible for any photons to reach it," Smith said. "Also, the parapineal organ is regarded as completely absent."

In rats, however, the pineal organ is close to the surface. Some photosensitive proteins are still expressed in the organ in embryonic rats, suggesting that the third eye didn't completely disappear in the rodent lineage.

Smith and her team are not sure which organ — the pineal or parapineal — led to the formation of the third eye in early mammals. When that mystery is solved, they should gain a better understanding of why the extra eye was lost over time in mammals.

What is clearer is that the third eye of today's lizards, the pineal organ, evolved independently from the third eye of other jawed vertebrates.

"We should stress that the idea that the lizard third eye is not the same as the third eye of frogs or fish was proposed before," Smith said. "But it has not been universally accepted. By finding a species in which both pineal organs were simultaneously developed as eyes, where the front one was clearly the typical lizard third eye, we could confirm this idea."

Although the extinct monitor's extra eyes were located close together, the researchers do not think that they functioned as a pair in the same way that typical eyes do.

"They are indeed closely spaced, but their central neural connections with the rest of the brain are different," Smith explained.

Saniwa ensidens lived in parts of Wyoming and Europe during the Eocene epoch around 48 million years ago. It holds the distinction of being the first fossil lizard ever known from North America. Now it has yet another claim to animal fame — at least for now.

The new finding "tells us how easy it is, in terms of evolution, to self-assemble a complex organ under certain circumstances,” said Bhullar, a paleontologist at Yale. “Eyes are classically thought of as these remarkably complex structures. In fact, the brain is just waiting to make eyes at all times.”

He added that eyes are "fundamentally a part of the brain" and that their formation "is part of the process of how the brain comes in contact with part of the skin."

Smith said that as an embryo develops, the central nervous system begins as an "infolding of the outermost layer of the embryo." This layer is called the neuroectoderm.

Read more at Seeker

Apr 2, 2018

Finding order in disorder demonstrates a new state of matter

This is Cristiano Nisoli.
Physicists have identified a new state of matter whose structural order operates by rules more aligned with quantum mechanics than standard thermodynamic theory. In a classical material called artificial spin ice, which in certain phases appears disordered, the material is actually ordered, but in a "topological" form.

"Our research shows for the first time that classical systems such as artificial spin ice can be designed to demonstrate topological ordered phases, which previously have been found only in quantum conditions," said Los Alamos National Laboratory physicist Cristiano Nisoli, leader of the theoretical group that collaborated with an experimental group at the University of Illinois at Urbana-Champaign, led by Peter Schiffer (now at Yale University).

Physicists generally classify the phases of matter as ordered, such as crystal, and disordered, such as gases, and they do so on the basis of the symmetry of such order, Nisoli said.

"The demonstration that these topological effects can be designed into an artificial spin ice system opens the door to a wide range of possible new studies," Schiffer said.

Specialized material maintained puzzling energy levels in experiments

In the new research, the team explored a particular artificial spin ice geometry, called Shakti spin ice. While these materials are theoretically designed, this time, the discovery of its exotic, out-of-equilibrium properties proceeded from experiments to theory.

Performing photoemission electron microscopy characterization at the U.S. Department of Energy's Advanced Light Source at Lawrence Berkeley National Laboratory, Schiffer's team revealed something puzzling: Unlike other artificial spin ices, which could reach their low-energy state as temperature was reduced in successive quenches, Shakti spin ice stubbornly remained at about the same energy level. "The system gets stuck in a way that it cannot rearrange itself, even though a large-scale rearrangement would allow it to fall to a lower energy state," Schiffer said.

Clearly, something was being conserved, but nothing appeared as an obvious candidate in a material artificially devised to provide a disordered spin picture.

Backing off to see the big picture

Moving away from a spin picture and concentrating on an emergent description of the excitations of the system, Nisoli described a low-energy state that could be mapped exactly into a celebrated theoretical model, the "dimer cover model," whose topological properties had been recognized before. Then, data from the experiment confirmed topological charge conservation and thus a long lifetime for the excitations.

"I find it most intriguing because usually theoretical frameworks move from classical physics to quantum physics. Not so with topological order," Nisoli said.

Read more at Science Daily

Cosmic lens helps Hubble capture image of most distant star ever seen

Icarus, whose official name is MACS J1149+2223 Lensed Star 1, is the farthest individual star ever seen. It is only visible because it is being magnified by the gravity of a massive galaxy cluster, located about 5 billion light-years from Earth. Called MACS J1149+2223, this cluster, shown at left, sits between the Earth and the galaxy that contains the distant star. The team had been using Hubble to monitor a supernova in the far-off spiral galaxy when, in 2016, they spotted a point of light near the supernova that began to brighten. Even though the object subsequently became three times brighter in one month, the colors of the light coming from the object did not change. Analysis of these colors showed it was a blue supergiant star in the background galaxy whose magnification grew for several weeks due to an intervening object, probably a star, in the galaxy cluster. The panels at the right show the view in 2011, without Icarus visible, compared with the star's brightening in 2016.
Thanks to a rare cosmic alignment, astronomers have captured the most distant normal star ever observed, some 9 billion light years from Earth.

While astronomers routinely study galaxies much farther away, they're visible only because they glow with the brightness of billions of stars. And a supernova, often brighter than the galaxy in which it sits, also can be visible across the entire universe.

Beyond a distance of about 100 million light years, however, the stars in these galaxies are impossible to make out individually.

But a phenomenon called gravitational lensing -- the bending of light by massive galaxy clusters in the line of sight -- can magnify the distant universe and make dim, far away objects visible. Typically, lensing magnifies galaxies by up to 50 times, but in this case, the star was magnified more than 2,000 times. It was discovered in NASA Hubble Space Telescope images taken in late April of 2016 and as recently as April 2017.

"You can see individual galaxies out there, but this star is at least 100 times farther away than the next individual star we can study, except for supernova explosions," said former UC Berkeley postdoctoral scholar Patrick Kelly, now on the faculty at the University of Minnesota, Twin Cities. Kelly is first author of a paper about the discovery appearing online this week in advance of publication in the journal Nature Astronomy.

The discovery of the star, which astronomers often refer to as Icarus rather than by its formal name, MACS J1149 Lensed Star 1 (LS1), kicks off a new technique for astronomers to study individual stars in galaxies formed during the earliest days of the universe. These observations can provide a rare look at how stars evolve, especially the most luminous ones.

"For the first time ever we're seeing an individual normal star -- not a supernova, not a gamma ray burst, but a single stable star -- at a distance of nine billion light years," said Alex Filippenko, a professor of astronomy at UC Berkeley and one of many co-authors of the report. "These lenses are amazing cosmic telescopes."

The astronomy team also used Icarus to test and reject one theory of dark matter -- that it consists of numerous primordial black holes lurking inside galaxy clusters -- and to probe the make-up of normal matter and dark matter in the galaxy cluster.

Einstein ring

Kelly noticed the star while monitoring a supernova he had discovered in 2014 while using Hubble to peer through a gravitational lens in the constellation Leo. That supernova, dubbed SN Refsdal in honor of the late Norwegian astrophysicist Sjur Refsdal, a pioneer of gravitational lensing studies, was split into four images by the lens, a massive galaxy cluster called MACS J1149+2223, located about 5 billion light years from Earth.

Suspecting that Icarus might be more highly magnified than SN Refsdal, Kelly and his team analyzed the colors of the light coming from it and discovered it was a single star, a blue supergiant. This B-type star is much larger, more massive, hotter and possibly hundreds of thousands of times intrinsically brighter than our Sun, though still much too far away to see without the amplification of gravitational lensing.

By modeling the lens, they concluded that the tremendous apparent brightening of Icarus was probably caused by a unique effect of gravitational lensing. While an extended lens, like a galaxy cluster, can only magnify a background object up to 50 times, smaller objects can magnify much more. A single star in a foreground lens, if precisely aligned with a background star, can magnify the background star thousands of times. In this case, a star about the size of our sun briefly passed directly through the line of sight between the distant star Icarus and Hubble, boosting its brightness more than 2,000 times.

In fact, if the alignment was perfect, that single star within the cluster turned the light from the distant star into an "Einstein ring": a halo of light created when light from the distant star bends around all sides of the lensing star. The ring is too small to discern from this distance, but the effect made the star easily visible by magnifying its apparent brightness.

Kelly saw a second star in the Hubble image, which could either be a mirror image of Icarus, or a different star being gravitationally lensed.

Read more at Science Daily