Mouth clicks used in human echolocation captured in unprecedented detail

Illustration of acoustic pattern of mouth clicks for human echolocation.

Like some bats and marine mammals, people can develop expert echolocation skills, in which they produce a clicking sound with their mouths and listen to the reflected sound waves to "see" their surroundings. A new study published in PLOS Computational Biology provides the first in-depth analysis of the mouth clicks used in human echolocation.

The research, performed by Lore Thaler of Durham University, U.K., Galen Reich and Michael Antoniou of Birmingham University, U.K., and colleagues, focuses on three blind adults who have been expertly trained in echolocation. Since the age of 15 or younger, all three have used echolocation in their daily lives. They use the technique for such activities as hiking, visiting unfamiliar cities, and riding bicycles.

While the existence of human echolocation is well documented, the details of the underlying acoustic mechanisms have been unclear. In the new study, the researchers set out to provide physical descriptions of the mouth clicks used by each of the three participants during echolocation. They recorded and analyzed the acoustic properties of several thousand clicks, including the spatial path the sound waves took in an acoustically controlled room.

Analysis of the recordings revealed that the clicks made by the participants had a distinct acoustic pattern that was more focused in its direction than that of human speech. The clicks were brief -- around three milliseconds long -- and their strongest frequencies were between two to four kilohertz, with some additional strength around 10 kilohertz.

The researchers also used the recordings to propose a mathematical model that could be used to synthesize mouth clicks made during human echolocation. They plan to use synthetic human clicks to investigate how these sounds can reveal the physical features of objects; the number of measurements required for such studies would be impractical to ask from human volunteers.

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Reconstructing life at its beginning, cell by cell

The virtual embryo offers predictions which cells express -- for example -- the genes even skipped (red) and twist (green). To appreciate the spatial distribution, researchers can look at the fly embryo from all angles.

After 13 rapid divisions a fertilized fly egg consists of about 6,000 cells. They all look alike under the microscope. However, each cell of a Drosophila melanogaster embryo already knows by then whether it is destined to become a neuron or a muscle cell -- or part of the gut, the head, or the tail. Now, Nikolaus Rajewsky's and Robert Zinzen's teams at the Berlin Institute of Medical Systems Biology (BIMSB) of the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) have analyzed the unique gene expression profiles of thousands of single cells and reassembled the embryo from these data using a new spatial mapping algorithm. The result is a virtual fly embryo showing exactly which genes are active where at this point in time. "It is basically a transcriptomic blueprint of early development," says Robert Zinzen, head of the Systems Biology of Neural Tissue Differentiation Lab. Their paper appears as a First Release in the online issue of Science.

"Only recently has it become possible to analyze genome-wide gene expression of individual cells at a large scale. Nikolaus recognized the potential of this technology very early on and established it in his lab," says Zinzen. "He started to wonder whether -- given a complex organized tissue -- one would be able to compute genome-wide spatial gene expression patterns from single-cell transcriptome data alone." BIMSB combines laboratories with different backgrounds and expertise, emphasizing the need of bringing computing power to biological problems. It turns out the institute had not only the perfect model system -- the Drosophila embryo -- to address Rajewsky's question, but also the right people with the right expertise, from physics and mathematics to biochemistry and developmental biology.

"The virtual embryo is much more than merely a cell mapping exercise," says Nikolaus Rajewsky, head of the Systems Biology of Gene Regulatory Elements Lab, who enjoyed returning to fly development 15 years after studying gene regulatory elements in Drosophila embryos during his post-doctoral time at the Rockefeller University. Using the interactive Drosophila Virtual Expression eXplorer (DVEX) database, researchers can now look at any of about 8,000 expressed genes in each cell and ask, "Gene X, where are you expressed and at what level? What other genes are active at the same time and in the same cells?" It also works with the enigmatic long non-coding RNAs. "Instead of time-consuming imaging experiments, scientists can do virtual ones to identify new regulatory players and even get ideas for biological mechanisms," says Rajewsky. "What would normally take years using standard approaches can now be done in a couple of hours."

Breaking the synchronicity of the first cell divisions

In their paper, the MDC researchers describe a dozen new transcription factors and many more long non-coding RNAs that have never been studied before. Also, they propose an answer to a question that has puzzled scientists for 35 years: How does the embryo break synchronicity of cell divisions to develop more complex structures?

In a process called gastrulation, distinct germ layers form and cells become restricted with regard to which tissues and organs they may differentiate into. "We believe that the Hippo signaling pathway is at least partly responsible for setting up gastrulation," says Rajewsky. The pathway controls organ size, cell cycles and cell proliferation, but had never been implicated in the development of the early embryo. "We not only showed that Hippo is active in the fly, but we could even predict in which regions of the embryo this would lead to a different onset of mitosis and therefore break synchronicity. And that is just one example for how useful our tool is to understand mechanisms that have escaped traditional science."

Project underwent a tough gestation period

When the researchers started creating the virtual embryo, they did not know whether it would be possible. A key pillar of their eventual success is the Drop-Seq technology, a droplet-based, microfluidic method that allows the transcriptional profiling of thousands of individual cells at low cost. This technique had been newly set up in the Rajewsky lab by Jonathan Alles, a summer student.

However, the fly embryos needed to be selected precisely at the onset of gastrulation. Philipp Wahle, a PhD student in Robert Zinzen's lab, hand-picked about 5,000 of them before dissociating them into single cells. "I was convinced this would give us a large and completely unique data set. This was a great motivation for me," says Wahle. That laborious process created a new challenge. "You need to collect over several sessions to have enough material for a sequencing run," says Christine Kocks, who led the single-cell sequencing team. It was composed of Jonathan Alles, Salah Ayoub and Anastasiya Boltengagen, who jointly with computational scientist Nikos Karaiskos optimized the droplet-based sequencing. "So we had to find a way to stabilize the transcriptomes in the cells," added Kocks. "Finally, based on his earlier work with C. elegans embryos, Nikolaus suggested using methanol." The new single-cell fixation method was published in BMC Biology in May 2017.

As the data got better and better, Nikos Karaiskos, a theoretical physicist and computational expert in Rajewsky's lab, took on the challenge of spatially mapping such a large number of cells to their precise embryonic position. None of the existing approaches in the field of spatial transcriptomics was suitable to reconstruct the Drosophila embryo. "It was a reiterative process to filter the data, see what is inside and try to map it. It changed many times along the way," says Karaiskos. There was a lot of back and forth between members of the computer lab and wet lab -- exchanges that are a defining characteristic of the BIMSB. "I had to question my work all the time, see where it was lacking and develop something better." He came up with a new algorithm called DistMap that can map transcriptomic data of cells back to their original position in the virtual embryo.

Navigating unchartered territory

The construction of the virtual embryo allowed Karaiskos to readily predict the expression of thousands of genes, an almost impossible task by traditional experimental means. Philipp Wahle, supported by Claudia Kipar, validated these predictions by visualizing the gene expression profiles at the bench with a traditional approach: In situ hybridization allows visualizing patterns of gene expression with colorful dyes that are visible under the microscope. "At this stage, a single layer of cells surrounds the entire fly embryo," says Wahle. "This makes it very accessible, thus enabling you to compare the computational data with imaging."

It is the first time that it has been possible to look at the about 6,000 cells of the embryo individually, assess their gene expression profiles -- and understand what determines their behavior in the embryo. "The most important technological advance of this study is that we don't lose the spatial information that is required to understand how embryonic cells act in concert," say the scientists. "This really is unchartered territory and requires new bioinformatics approaches to make sense of the collected data. This worked beautifully in our collaboration, not least because of the unique make-up of the Rajewsky lab, which integrates wet lab and computational approaches." One major advantage is that both groups are not only interested in technology but have specific biological questions that motivate them, says Rajewsky. "Robert has a deep understanding of early development. We can do single-cell sequencing runs and have the computational power to develop the tools that help us actually understand the underlying gene regulatory interactions."

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First hints of possible water content on TRAPPIST-1 planets

This artist's impression shows the view from the surface of one of the planets in the TRAPPIST-1 system. At least seven planets orbit this ultracool dwarf star 40 light-years from Earth and they are all roughly the same size as the Earth. Several of the planets are at the right distances from their star for liquid water to exist on the surfaces.

An international team of astronomers used the NASA/ESA Hubble Space Telescope to estimate whether there might be water on the seven earth-sized planets orbiting the nearby dwarf star TRAPPIST-1. The results suggest that the outer planets of the system might still harbour substantial amounts of water. This includes the three planets within the habitable zone of the star, lending further weight to the possibility that they may indeed be habitable.

On 22 February 2017 astronomers announced the discovery of seven Earth-sized planets orbiting the ultracool dwarf star TRAPPIST-1, 40 light-years away. This makes TRAPPIST-1 the planetary system with the largest number of Earth-sized planets discovered so far.

Following up on the discovery, an international team of scientists led by the Swiss astronomer Vincent Bourrier from the Observatoire de l'Université de Genève, used the Space Telescope Imaging Spectrograph (STIS) on the NASA/ESA Hubble Space Telescope to study the amount of ultraviolet radiation received by the individual planets of the system. "Ultraviolet radiation is an important factor in the atmospheric evolution of planets," explains Bourrier. "As in our own atmosphere, where ultraviolet sunlight breaks molecules apart, ultraviolet starlight can break water vapour in the atmospheres of exoplanets into hydrogen and oxygen."

While lower-energy ultraviolet radiation breaks up water molecules -- a process called photodissociation -- ultraviolet rays with more energy (XUV radiation) and X-rays heat the upper atmosphere of a planet, which allows the products of photodissociation, hydrogen and oxygen, to escape.

As it is very light, hydrogen gas can escape the exoplanets' atmospheres and be detected around the exoplanets with Hubble, acting as a possible indicator of atmospheric water vapour. The observed amount of ultraviolet radiation emitted by TRAPPIST-1 indeed suggests that the planets could have lost gigantic amounts of water over the course of their history.

This is especially true for the innermost two planets of the system, TRAPPIST-1b and TRAPPIST-1c, which receive the largest amount of ultraviolet energy. "Our results indicate that atmospheric escape may play an important role in the evolution of these planets," summarises Julien de Wit, from MIT, USA, co-author of the study.

The inner planets could have lost more than 20 Earth-oceans-worth of water during the last eight billion years. However, the outer planets of the system -- including the planets e, f and g which are in the habitable zone -- should have lost much less water, suggesting that they could have retained some on their surfaces. The calculated water loss rates as well as geophysical water release rates also favour the idea that the outermost, more massive planets retain their water. However, with the currently available data and telescopes no final conclusion can be drawn on the water content of the planets orbiting TRAPPIST-1.

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Fossil footprints challenge established theories of human evolution

The footprints were discovered by Gerard Gierlinski (1st author of the study) by chance when he was on holiday on Crete in 2002. Gierlinski, a paleontologist at the Polish Geological Institute specialized in footprints, identified the footprints as mammal but did not interpret them further at the time. In 2010 he returned to the site together with Grzegorz Niedzwiedzki (2nd author), a Polish paleontologist now at Uppsala University, to study the footprints in detail. Together they came to the conclusion that the footprints were made by hominins.

Newly discovered human-like footprints from Crete may put the established narrative of early human evolution to the test. The footprints are approximately 5.7 million years old and were made at a time when previous research puts our ancestors in Africa -- with ape-like feet.

Ever since the discovery of fossils of Australopithecus in South and East Africa during the middle years of the 20th century, the origin of the human lineage has been thought to lie in Africa. More recent fossil discoveries in the same region, including the iconic 3.7 million year old Laetoli footprints from Tanzania which show human-like feet and upright locomotion, have cemented the idea that hominins (early members of the human lineage) not only originated in Africa but remained isolated there for several million years before dispersing to Europe and Asia. The discovery of approximately 5.7 million year old human-like footprints from Crete, published online this week by an international team of researchers, overthrows this simple picture and suggests a more complex reality.

Human feet have a very distinctive shape, different from all other land animals. The combination of a long sole, five short forward-pointing toes without claws, and a hallux ("big toe") that is larger than the other toes, is unique. The feet of our closest relatives, the great apes, look more like a human hand with a thumb-like hallux that sticks out to the side. The Laetoli footprints, thought to have been made by Australopithecus, are quite similar to those of modern humans except that the heel is narrower and the sole lacks a proper arch. By contrast, the 4.4 million year old Ardipithecus ramidus from Ethiopia, the oldest hominin known from reasonably complete fossils, has an ape-like foot. The researchers who described Ardipithecus argued that it is a direct ancestor of later hominins, implying that a human-like foot had not yet evolved at that time.

The new footprints, from Trachilos in western Crete, have an unmistakably human-like form. This is especially true of the toes. The big toe is similar to our own in shape, size and position; it is also associated with a distinct 'ball' on the sole, which is never present in apes. The sole of the foot is proportionately shorter than in the Laetoli prints, but it has the same general form. In short, the shape of the Trachilos prints indicates unambiguously that they belong to an early hominin, somewhat more primitive than the Laetoli trackmaker. They were made on a sandy seashore, possibly a small river delta, whereas the Laetoli tracks were made in volcanic ash.

'What makes this controversial is the age and location of the prints,' says Professor Per Ahlberg at Uppsala University, last author of the study.

At approximately 5.7 million years, they are younger than the oldest known fossil hominin, Sahelanthropus from Chad, and contemporary with Orrorin from Kenya, but more than a million years older than Ardipithecus ramidus with its ape-like feet. This conflicts with the hypothesis that Ardipithecus is a direct ancestor of later hominins. Furthermore, until this year, all fossil hominins older than 1.8 million years (the age of early Homo fossils from Georgia) came from Africa, leading most researchers to conclude that this was where the group evolved. However, the Trachilos footprints are securely dated using a combination of foraminifera (marine microfossils) from over- and underlying beds, plus the fact that they lie just below a very distinctive sedimentary rock formed when the Mediterranean sea briefly dried out, 5.6 millon years ago. By curious coincidence, earlier this year, another group of researchers reinterpreted the fragmentary 7.2 million year old primate Graecopithecus from Greece and Bulgaria as a hominin. Graecopithecus is only known from teeth and jaws.

During the time when the Trachilos footprints were made, a period known as the late Miocene, the Sahara Desert did not exist; savannah-like environments extended from North Africa up around the eastern Mediterranean. Furthermore, Crete had not yet detached from the Greek mainland. It is thus not difficult to see how early hominins could have ranged across south-east Europe and well as Africa, and left their footprints on a Mediterranean shore that would one day form part of the island of Crete.

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The First Adhesive Was Invented by Neanderthals 200,000 Years Ago

Reconstruction of the environment of a Neanderthal man in the mid-Paleolithic period (80,000 BC)

Neanderthals — early members of the genus Homo from Europe and Asia — have had such a lowly standing on the human family tree that the very word Neanderthal is often synonymous with archaic ways and ignorance.

Neanderthals, however, had big brains, complex societies, and tools so useful that some designs created for leatherworking are still in use today. Many researchers even believe that a true extinction of Neanderthals might not have occurred, but that these individuals instead were absorbed into what evolved to be current Homo sapiens. To this day, people of European and Asian heritage retain Neanderthal DNA.

Excavations over the past few decades have unearthed tar lumps and adhesive residues on stone tools at Neanderthal sites in Germany. Some anthropologists have claimed that adhesive production is a high-tech skill associated with anatomically modern humans, yet new research published in the journal Scientific Reports not only supports that Neanderthals invented adhesives, but also it explains how they probably achieved the feat.

“Right now, the oldest evidence we have points to Neanderthals inventing adhesives at least 200,000 years ago in Europe,” lead author Paul Kozowyk said.

Kozowyk, a researcher at Leiden University, and his team analyzed archaeological evidence for early tar production. They additionally conducted experiments based on Neanderthal know-how to determine how the early Eurasians managed to invent tar, an adhesive that helped to strengthen and waterproof bindings made of sinew, hide, or plant fibers used to attach bone or stone tools to handles. The technique, known as hafting with tar, was also extended to weapon production, such as improving spears employed for hunting.

The researchers propose as many as three tar production methods could have been developed by Neanderthals. The first, called "ash mound," required placing ambers and ash over a roll of birch bark tied with fresh wood fiber to keep it tight. The scientists determined that care must be taken to balance the ratio between embers and ash, which helps to keep oxygen out and promotes the production of tar that can then be scraped off the roll.

Experimentally produced birch bark tar dripping from a flint flake

The second method demonstrated by the researchers, "pit roll,” required placing hot embers directly on top of a birch bark roll placed over a pit, which produced tar.

The other method, “raised structure,” was the most sophisticated of all in the study. It involved putting a container made of birch bark in a pit. A loose roll of bark was then placed on organic mesh covering the pit. The researchers covered the bark with dirt and lit a fire over the entire mound. This technique, which required more wood, time, and set-up than the other methods, yielded the most tar.

“It's possible that all three methods we tested, or even some different methods, were used depending on the needs or requirements at the time,” Kozowyk said. “For example, a major service to a Neanderthal tool kit might have called for something like the raised structure to produce lots of tar for multiple tools.”

“On the other hand,” he added, “a small hunting camp requiring a quick repair may have only needed a small amount of tar, and then a simpler method would be much more practical. My personal favorite is the pit roll method, because it's simple, but still produced reasonable quantities of tar.”

Tar collected in a birch bark container from the "pit roll" experiment, a technique which uses glowing embers placed over a roll of bark in a small pit.

The earliest evidence so far for adhesive production by anatomically modern humans dates to around 70,000 years ago, according to the researchers. It is likely that members of Homo sapiens in Africa figured out how to create tar on their own — a case of independent invention — but scientists have not ruled out that they learned the birch bark tar production techniques from Neanderthals.

Tar has many possible functions. Kozowyk, though, said, “During the Paleolithic, it’s unlikely that tar was used for much more than hafting tools.”

“In historic times," he added, "tar was used to waterproof boats and ships, containers and to protect wooden buildings, so its use is not limited to hafting tools. But these require production on an industrial scale that is not seen until more recently.”

Placing materials in ceramic containers can help with tar production. There is no evidence that Neanderthals ever produced pottery, however.

“There was probably no need for pottery until quite recently — speaking on a scale including hundreds of thousands of years of human evolution — and even in most modern human hunter-gatherer societies, pottery is an exception,” Kozowyk explained.

Neanderthals and early anatomically modern humans might have instead crafted containers out of wood and plant fibers. But if they did, preservation of such items is so poor that there is no firm evidence of them dating to the times of the oldest tar production.

Neanderthals and anatomically modern humans diverged long before then. An emerging theory is that the divergence occurred at least 500,000 years ago, with each group evolving on its own path until interbreeding occurred. The latter mixing, as well as similarities among the groups, however, have many anthropologists believing that Neanderthals and other hominids, such as Denisovans, should be considered as Homo sapiens.

“I used to argue that ‘anatomically modern humans’ — including fossils that essentially look like us today — are the only group that should be called Homo sapiens,” Chris Stringer of the Natural History Museum in London said. “Now, I think that anatomically modern humans are only a sub-group within the species Homo sapiens, and that we should recognize the diversity of forms within early Homo sapiens, some of which probably went extinct.”

Approximately 0.3 ounces of birch bark tar produced using the "raised structure" technique being prepared for analysis in the lab

The jury is still out on what exactly happened to Neanderthals. Some researchers have suggested that anatomically modern humans killed them off, or — like early colonizers of the Americas infecting native populations — spread diseases for which Neanderthals had no immunity. Kozowyk shared his view.

“What happened to Neanderthals was probably the result of a number of complex processes including, but not necessarily limited to, interbreeding with some cultural interaction, competition in some form, and a low Neanderthal population that led to them eventually being genetically overrun by the arriving modern human populations,” he said. “But this also likely varied from one region to another.”

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Oh, Snap! Trap-Jaw Ants Clamp Down on Prey in Half a Millisecond

While at least four different groups of ants have independently evolved systems involving a latch, spring, and trigger to power their fast-moving mandibles, the researchers have discovered that Myrmoteras ants' jaws work differently than those of any other known ant.

When your food moves fast, you’ve got to move faster.

For a type of southeast Asian ant, it helps that your jaw is spring-loaded to snap shut on prey in a tiny fraction of the time it takes a human to blink an eye.

The long, thin, spiny mandible of ants from the genus Myrmoteras open up at a 270-degree angle and lock into position, ready to snap shut when it moves on its most common prey — a jumping flea-like bug known as a springtail. When the ant is ready, a bulging spring of bone-like material at the back of the head releases the jaw, which snaps shut in half a millisecond — reaching speeds up to 60 mph in the process and spearing the springtail.

“Trap-jaw ants are likely evolving these really fast jaws for this specialized diet in sort of like an arms race,” said Fred Larabee, an evolutionary biologist at the Smithsonian Institution. “In order to capture their food, they have to have faster predation mechanisms than the prey they’re seeking out.”

Larabee, who works at the National Museum of Natural History in Washington DC, recently used high-powered imagery to capture the mechanism behind Myrmoteras mandibles for the first time.

The ants are native to Southeast Asia. The two Myrmoteras species in Larabee’s study were collected in Malaysia, where they live among leaf litter on the island of Borneo.

They’re one of several types of trap-jaw ants, some of which have more powerful jaws. But the mechanics of the ants in Larabee’s study were less well known. So he and his colleagues put the insects under a micro-CT scan and filmed them with a high-speed camera that captured 50,000 frames a second to reveal their movements.

“Their heads are very strangely shaped and they have this really prominent lobe on the back of the head,” he said. “While the mandibles are locked open, the closer muscle is able to supply tension to that spring in the back of the head.” When the jaw releases, “You can see that structure sort of caving in on the head. There’s a very clear deformation.”

Larabee and his colleagues published their findings today in the Journal of Experimental Biology. The high-speed camera helped them pinpoint the speed of the jaws, while the CT scanner — which uses X-rays to produce a 3D image — “was really useful to look at the structures.”

“It’s a great tool for studying insect anatomy because you can resolve really small, delicate features of internal anatomy without having to break open the specimen,” Larabee said. “Being able to visualize that in a 3D environment is even more beneficial, because you can digitally dissect different parts and visualize just the pieces you’re really interested in.”

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Scientists recover nova first spotted 600 years ago by Korean astrologers

This image shows the recovered nova of March 11, 1437 and its ejected shell. It was taken with the Carnegie SWOPE 1-meter telescope in Chile using a filter that highlights the hot hydrogen gas of the shell. The now-quiescent star that produced the nova shell is indicated with red tick marks; it is far from the shell's center today. However, its measured motion across the sky places it at the red '+' in 1437. The position of the center of the shell in 1437 is at the green plus sign. The agreement of the 1437 positions of the shell center and of the old nova are the 'clock' that demonstrates that the old nova of 1437 A.D. really is the source of the shell.

On a cold March night in Seoul almost 600 years ago, Korean astrologers spotted a bright new star in the tail of the constellation Scorpius. It was seen for just 14 days before fading from view. From these ancient records, modern astronomers determined that what the Royal Imperial Astrologers saw was a nova explosion, but they had been unable to find the binary star system that caused it -- until now.

A new study published today by the journal Nature pinpoints the location of the old nova, which now undergoes smaller-scale "dwarf nova" eruptions. The work supports that idea that novae go through a very long-term life cycle after erupting, fading to obscurity for thousands of years, and then building back up to become full-fledged novae once more.

"This is the first nova that's ever been recovered with certainty based on the Chinese, Korean, and Japanese records of almost 2,500 years," said the study's lead author Michael Shara, a curator in the American Museum of Natural History's Department of Astrophysics.

A nova is a colossal hydrogen bomb produced in a binary system where a star like our Sun is being cannibalized by a white dwarf -- a dead star. It takes about 100,000 years for the white dwarf to build up a critical layer of hydrogen that it steals from the sun-like star, and when it does, it blows the envelope off, producing a burst of light that makes the star up to 300,000 times brighter than the sun for anywhere from a few days to a few months.

For years, Shara has tried to pinpoint the location of the binary star that produced the nova eruption in 1437, along with Durham University's Richard Stephenson, a historian of ancient Asian astronomical records, and Liverpool John Moores University astrophysicist Mike Bode. Recently, they expanded the search field and found the ejected shell of the classical nova. They confirmed the finding with another kind of historical record: a photographic plate from 1923 taken at the Harvard Observatory station in Peru and now available online as part of the Digitizing a Sky Century at Harvard (DASCH) project.

"With this plate, we could figure out how much the star has moved in the century since the photo was taken," Shara said. "Then we traced it back six centuries, and bingo, there it was, right at the center of our shell. That's the clock, that's what convinced us that it had to be right."

Other DASCH plates from the 1940s helped reveal that the system is now a dwarf nova, indicating that so-called "cataclysmic binaries" -- novae, novae-like variables, and dwarf novae -- are one and the same, not separate entities as has been previously suggested. After an eruption, a nova becomes "nova-like," then a dwarf nova, and then, after a possible hibernation, comes back to being nova-like, and then a nova, and does it over and over again, up to 100,000 times over billions of years.

"In the same way that an egg, a caterpillar, a pupa, and a butterfly are all life stages of the same organism, we now have strong support for the idea that these binaries are all the same thing seen in different phases of their lives," Shara said. "The real challenge in understanding the evolution of these systems is that unlike watching the egg transform into the eventual butterfly, which can happen in just a month, the lifecycle of a nova is hundreds of thousands of years. We simply haven't been around long enough to see a single complete cycle. The breakthrough was being able to reconcile the 580-year-old Korean recording of this event to the dwarf nova and nova shell that we see in the sky today."

This study was based on observations from the Southern African Large Telescope (SALT), and the Las Campanas Observatories' Swope and Dupont telescopes.

Other authors on this study include K. Ilkiewicz, J. Mikolajewska, and K. Drozd from the Polish Academy of Sciences; A. Pagnotta, J. Faherty, and D. Zurek from the American Museum of Natural History; L.A. Crause from the South African Astronomical Observatory; I. Fuentes-Morales and C. Tappert from the Instituto de Física y Astronomía; J.E. Grindlay from the Harvard-Smithsonian Center for Astrophysics; A.F.J. Moffat from the Université de Montréal; M.L. Pretorius from the South African Astronomical Observatory and the University of Capetown; and L. Schmidtobreick from the European Southern Observatory.

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What lit up the universe? Black holes may have punctured darkened galaxies, allowing light to escape

The earliest known galaxies in the universe. Some of these galaxies formed just 600 million years after the Big Bang.

Soon after the Big Bang, the universe went completely dark.

The intense, seminal event that created the cosmos churned up so much hot, thick gas that light was completely trapped. Much later -- perhaps as many as one billion years after the Big Bang -- the universe expanded, became more transparent, and eventually filled up with galaxies, planets, stars, and other objects that give off visible light. That's the universe we know today.

How it emerged from the cosmic dark ages to a clearer, light-filled state remains a mystery.

In a new study, researchers at the University of Iowa offer a theory of how that happened. They think black holes that dwell in the center of galaxies fling out matter so violently that the ejected material pierces its cloudy surroundings, allowing light to escape. The researchers arrived at their theory after observing a nearby galaxy from which ultraviolet light is escaping.

"The observations show the presence of very bright X-ray sources that are likely accreting black holes," says Philip Kaaret, professor in the UI Department of Physics and Astronomy and corresponding author on the study. "It's possible the black hole is creating winds that help the ionizing radiation from the stars escape. Thus, black holes may have helped make the universe transparent."

Kaaret and his team focused on a galaxy called Tol 1247-232, located some 600 million light years from Earth, one of only three nearby galaxies from which ultraviolet light has been found to escape. In May 2016, using an Earth-orbiting telescope called Chandra, the researchers saw a single X-ray source whose brightness waxed and waned and was located within a vigorous star-forming region of Tol 1247-232.

The team determined it was something other than a star.

"Stars don't have changes in brightness," Kaaret says. "Our sun is a good example of that.

"To change in brightness, you have to be a small object, and that really narrows it down to a black hole," he says.

But how would a black hole, whose intense gravitational pull sucks in everything around it, also eject matter?

The quick answer is no one knows for sure. Black holes, after all, are hard to study, in part because their immense gravitational pull allows no light to escape and because they're embedded deep within galaxies. Recently, however, astronomers have offered an explanation: The jets of escaping matter are tapping into the accelerated rotational energy of the black hole itself.

Imagine a figure skater twirling with outstretched arms. As the skater folds her arms closer to her body, she spins faster. Black holes operate much the same way: As gravity pulls matter inward toward a black hole, the black hole likewise spins faster. As the black hole's gravitational pull increases, the speed also creates energy.

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Huge hidden reservoirs of turbulent gas in distant galaxies

This illustration shows how gas falling into distant starburst galaxies ends up in vast turbulent reservoirs of cool gas extending 30,000 light-years from the central regions. ALMA has been used to detect these turbulent reservoirs of cold gas surrounding similar distant starburst galaxies. By detecting CH+ for the first time in the distant universe, this research opens up a new window of exploration into a critical epoch of star formation.

A team led by Edith Falgarone (Ecole Normale Supérieure and Observatoire de Paris, France) has used the Atacama Large Millimeter/submillimeter Array to detect signatures of the carbon hydride CH+ in distant starburst galaxies. The group identified strong signals of CH+ in five out of the six galaxies studied, including the Cosmic Eyelash. This research provides new information that helps astronomers understand the growth of galaxies and how a galaxy's surroundings fuel star formation.

"CH+ is a special molecule. It needs a lot of energy to form and is very reactive, which means its lifetime is very short and it can't be transported far. CH+ therefore traces how energy flows in the galaxies and their surroundings," said Martin Zwaan, an astronomer at ESO, who contributed to the paper.

How CH+ traces energy can be thought of by analogy to being on a boat in a tropical ocean on a dark, moonless night. When the conditions are right, fluorescent plankton can light up around the boat as it sails. The turbulence caused by the boat sliding through the water excites the plankton to emit light, which reveals the existence of the the turbulent regions in the underlying dark water. Since CH+ forms exclusively in small areas where turbulent motions of gas dissipates, its detection in essence traces energy on a galactic scale.

The observed CH+ reveals dense shock waves, powered by hot, fast galactic winds originating inside the galaxies' star forming regions. These winds flow through a galaxy, and push material out of it, but their turbulent motions are such that part of the material can be re-captured by the gravitational pull of the galaxy itself. This material gathers into huge turbulent reservoirs of cool, low-density gas, extending more than 30 000 light-years from the galaxy's star forming region.

"With CH+, we learn that energy is stored within vast galaxy-sized winds and ends up as turbulent motions in previously unseen reservoirs of cold gas surrounding the galaxy," said Falgarone, who is lead author of the new paper. "Our results challenge the theory of galaxy evolution. By driving turbulence in the reservoirs, these galactic winds extend the starburst phase instead of quenching it."

The team determined that galactic winds alone could not replenish the newly revealed gaseous reservoirs and suggests that the mass is provided by galactic mergers or accretion from hidden streams of gas, as predicted by current theory.

Read more at Science Daily

Robot probes mystery of prehistoric sea creature’s swimming style

A fossil of a plesiosaur.

A new study led by the University of Southampton has shed light on the swimming style of a prehistoric sea creature by creating a robot to mimic its movements.

A Southampton team including Luke Muscutt, a PhD student in Engineering and the Environment, worked with partners at the University of Bristol to analyse the propulsion method of plesiosaurs -marine reptiles that lived at the same time as dinosaurs and died out more than 65 million years ago.

Plesiosaurs are unique among vertebrates because they used two near-identical pairs of flippers to propel themselves through the water -- whereas other animals, including existing species such as turtles and sea lions, have differently constructed front and back sets, using the front ones mainly for thrust and the back ones for steering.

However, the propulsion dynamics of the plesiosaur have long been debated, with various theories proposed since the 1950s.

In a paper published today [Wednesday 30 August] in the journal Proceedings of the Royal Society B, Luke and his colleagues describe a series of water tank experiments they carried out using 3D printed flippers attached to a robotic mechanism to mimic a range of movement combinations.

They studied plesiosaur fossils and X-rays of existing flipper-powered animals to determine the shape of the large, wing-like flippers and the range of motions the robotic mechanism would need to reproduce.

The team found that swirling movements in the water created by the front flipper allowed for a major increase in thrust and efficiency by the back flipper (increasing thrust by up to 60 per cent and efficiency up to 40 per cent) -- strongly suggesting that plesiosaurs would have used all four flippers to propel themselves through the water.

Luke explained: "Fossils by themselves don't tell us much about how plesiosaurs actually moved. Short of genetically engineering a plesiosaur, our best available option was to create a robot to show how it might have happened.

"The results were amazing and indicate why plesiosaurs were such a successful species, retaining four flippers for more than 100 million years.

"If this wasn't the case, it's unlikely the four-flipper system would have been maintained for so long.

"Understanding how an animal might have moved gives us a better understanding of the animal as a whole -- for instance, how far it can travel, what animals it can predate on, and what it might have fallen prey to.

"Our observations of tandem flipper systems such as the plesiosaur's might also eventually have a real-world application -- as a propulsion system for undersea vehicles, for instance, that could help make them more manoeuvrable, efficient and quieter."

Colin Palmer, of the University of Bristol's School of Earth Sciences, added: "Our team has blended biology, palaeontology and engineering to produce a significant advance in our understanding of plesiosaurs' propulsion.

Read more at Science Daily

Volcanic eruptions drove ancient global warming event

Layered volcanic rocks in Eastern Greenland that are up to 4 miles thick were formed during ancient volcanic eruptions that caused a global warming event called the Palaeocene-Eocene Thermal Maximum (PETM).

A natural global warming event that took place 56 million years ago was triggered almost entirely by volcanic eruptions that occurred as Greenland separated from Europe during the opening of the North Atlantic Ocean, according to an international team of researchers that includes Andy Ridgwell, a University of California, Riverside professor of earth sciences.

The findings, published today in Nature, refute the more commonly favored explanation that the event, called the Palaeocene-Eocene Thermal Maximum (PETM), was caused by the release of carbon from sedimentary reservoirs such as frozen methane.

"While it has long been suggested that the PETM was caused by injection of carbon into the atmosphere and ocean, the mechanism has remained elusive until now," Ridgwell said. "By combining geochemical measurements and a global climate model that my group has been developing for over a decade, we have shown that this event was caused almost entirely by carbon emissions from the Earth's interior."

Scientists are interested in studying ancient warming events to understand how the Earth behaves when the climate system is dramatically perturbed. During the PETM, atmospheric carbon dioxide more than doubled and global temperatures rose by 5 degrees Celsius, an increase that is comparable with the change that may occur by later next century on modern Earth. While there was significant ecological disruption during the PETM, most species were able to avoid extinction via adaptation or migration. However, the rate of carbon addition during the onset of the PETM lasted for several thousand years, as described in a related Nature Communications paper by Sandra Kirtland Turner, an assistant professor of earth sciences at UCR, whereas current climate change is occurring on a century time-scale.

To identify the source of carbon during the PETM, the researchers studied the remains of tiny marine creatures called foraminifera, the shells of which shed light on the environmental conditions when they lived millions of years ago. By separating the different atomic masses ('isotopes') of the element boron in the foraminifera shells, they tracked how the pH of seawater changed during the PETM. By combining this data with Ridgwell's global climate model, the team deduced the amount of carbon added to the ocean and atmosphere and concluded that volcanic activity during the opening of the North Atlantic was the dominant force behind the PETM.

"The amount of carbon released during this time was vast -- more than 30 times larger than all the fossil fuels burned to date and equivalent to all the current conventional and unconventional fossil fuel reserves we could feasibly ever extract." Ridgwell said.

An unexpected finding was that enhanced organic matter burial was important in ultimately sequestering the released carbon and accelerating the recovery of the Earth's ecosystem without massive extinctions.

Read more at Science Daily

Sense of smell is key factor in bird navigation, new study shows

Cory's Shearwater, Calonectris borealis, in flight.

How do birds navigate over long distances? This complex question has been the subject of debate and controversy among scientists for decades, with Earth's magnetic field and the bird's own sense of smell among the factors said to play a part.

Now, researchers from the universities of Oxford, Barcelona and Pisa have shown in a new experiment that olfaction -- or sense of smell -- is almost certainly a key factor in long-distance oceanic navigation, eliminating previous misgivings about this hypothesis.

The research is published in the journal Scientific Reports.

Study leader Oliver Padget, a doctoral candidate in Oxford University's Department of Zoology, said: 'Navigation over the ocean is probably the extreme challenge for birds, given the long distances covered, the changing environment, and the lack of stable landmarks. Previous experiments have focused on the physical displacement of birds, combined with some form of sensory manipulation such as magnetic or olfactory deprivation. Evidence from these experiments has suggested that removing a bird's sense of smell impairs homing, whereas disruption of the magnetic sense has yielded inconclusive results.

'However, critics have questioned whether birds would behave in the same way had they not been artificially displaced, as well as arguing that rather than affecting a bird's ability to navigate, sensory deprivation may in fact impair a related function, such as its motivation to return home or its ability to forage.

'Our new study eliminates these objections, meaning it will be very difficult in future to argue that olfaction is not involved in long-distance oceanic navigation in birds.'

In this new experiment, the researchers closely followed the movements and behaviour of 32 free-ranging Scopoli's shearwaters off the coast of Menorca. The birds were split into three groups: one made temporarily anosmic (unable to smell) through nasal irrigation with zinc sulphate; another carrying small magnets; and a control group. Miniature GPS loggers were attached to the birds as they nested and incubated eggs in crevices and caves on the rocky Menorcan coast. But rather than being displaced, they were then tracked as they engaged in natural foraging trips.

All birds went out on foraging trips as normal, gained weight through successful foraging, and returned to exchange incubation periods with their partners. Thus, removing a bird's sense of smell does not appear to impair either its motivation to return home or its ability to forage effectively.

However, although the anosmic birds made successful trips to the Catalan coast and other distant foraging grounds, they showed significantly different orientation behaviour from the controls during the at-sea stage of their return journeys. Instead of being well-oriented towards home when they were out of sight of land, they embarked on curiously straight but poorly oriented flights across the ocean, as if following a compass bearing away from the foraging grounds without being able to update their position.

Their orientation then improved when approaching land, suggesting that birds must consult an olfactory map when out of sight of land but are subsequently able to find home using familiar landscape features.

Senior author Tim Guilford, Professor of Animal Behaviour and leader of the Oxford Navigation Group in Oxford's Department of Zoology, said: 'To the best of our knowledge, this is the first study that follows free-ranging foraging trips in sensorily manipulated birds. The displacement experiment has -- rightly -- been at the heart of bird navigation studies and has produced powerful findings on what birds are able to do in the absence of information collected on their outward journey.

Read more at Science Daily

Woolly rhino neck ribs provide clues about their decline and eventual extinction

Arrows indicate large articulation facets of cervical ribs on a fossil cervical vertebra of a woolly rhino of Naturalis, Leiden.

Researchers from the Naturalis Biodiversity Center in Leiden examined woolly rhino and modern rhino neck vertebrae from several European and American museum collections and noticed that the remains of woolly rhinos from the North Sea often possess a 'cervical' (neck) rib -- in contrast to modern rhinos.

The study, published in the open access journal PeerJ today, reports on the incidence of abnormal cervical vertebrae in woolly rhinos, which strongly suggests a vulnerable condition in the species. Given the considerable birth defects that are associated with this condition, the researchers argue it is very possible that developmental abnormalities contributed towards the eventual extinction of these late Pleistocene rhinos.

In modern animals, the presence of a 'cervical rib' (a rib attached to a cervical vertebra) is an unusual event, and is cause for further investigation. Though the rib itself is relatively harmless, this condition is often associated with inbreeding and adverse environmental conditions during pregnancy.

Frietson Galis, one of the authors of the peer-reviewed study, found a remarkably high percentage of these neck ribs in the woolly mammoth, published in a previous study.

"This aroused our curiosity to also check the woolly rhino, a species that, like the woolly mammoth lived during the late Pleistocene and similarly died out," said Alexandra van der Geer, one of the authors of the study. "The woolly rhino bones were all dredged from the North Sea and river deltas in the Netherlands. We knew these were just about the last rhinos living there, so we suspected something could be wrong here as well. Our work now shows that there was indeed a problem in the woolly rhino population."

The absence of cervical ribs in the modern sample is by no means evidence that rhino populations today are healthy. Museum collections are based on rhino specimens that were collected at least five decades ago. Rhinoceros numbers are dwindling extremely fast, especially the last two decades, resulting in near extinction for some species and the total extinction of the western black rhinoceros.

Read more at Science Daily

An alternative to wolf control to save endangered caribou

Mountain caribou in British Columbia, Canada, observed during a population census.

What happens when invasive and native species are eaten by the same predator? If the invasive species is abundant, the native species can go extinct because predator numbers are propped up by the invading species. This process is called "apparent competition" because on the surface it "appears" that the invading and native prey directly compete with each other, but really the shared predator links the two prey.

Apparent competition is an increasing problem, causing endangerment and extinction of native prey as abundant species colonize new areas in the wake of human-caused change to the environment. This is exactly what is happening to the iconic woodland caribou across North America. Prey like moose and white-tailed deer are expanding in numbers and range because of logging and climate change, which in turn increases predator numbers (e.g. wolves). With all these additional predators on the landscape, more caribou become by-catch, driving some herds to extinction.

A short-term solution would be to kill wolves but this can be seen as just a band aid, and is no longer politically acceptable in many jurisdictions. As a more ultimate solution, Serrouya and colleagues used a new government policy and treated it as an experiment, to maximize learning. The new policy was to reduce moose numbers to levels that existed prior to widescale logging, with an adjacent reference area where moose were not reduced. The results of this research are published in an article titled "Experimental moose reduction lowers wolf density and stops decline of endangered caribou," and is published today in the peer reviewed and open access journal PeerJ.

Following the reduction of moose using sport hunting, wolf number numbers declined, with wolf dispersal rates 2.5 × greater than the reference area, meaning that dispersal was the process leading to fewer wolves. Caribou annual survival increased from 0.78 to 0.88 for the Columbia North herd, located in the moose reduction area, but survival declined in the reference area (Wells Gray). The Columbia North herd probably stabilized as a result of the moose reduction, and has been stable for 14 years (2003 -- 2017). By expanding their comparison across western Canada and the lower 48 states, they found that a separate herd subjected to another moose reduction was also stable, whereas at least 15 other herds not subjected to moose reductions are continuing to decline.

Read more at Science Daily

Algae fortifies coral reefs in past and present

Lead author of the study Anna Weiss, a Ph.D. candidate in The University of Texas at Austin Jackson School of Geosciences, at a fossilized reef in Adnet, Austria.

The Great Barrier Reef, and most other large reefs around the world, owe their bulk in large part to a type of red algae that grows on corals and strengthens them. New research led by Anna Weiss, a Ph.D. candidate at The University of Texas at Austin Jackson School of Geosciences, has found that ancient coral reefs were also bolstered by their bond with red algae, a finding that could help scientists better understand how reefs will respond to climate change.

"Coral reefs as we know them today are a product of that long term coral-coralline algae relationship," Weiss said. "So if we want to preserve our coral reefs, we need to pay attention to the health of coralline algae as well."

Weiss conducted the research with Rowan Martindale, an assistant professor in the Jackson School's Department of Geological Sciences. Their research was published in August in the journal PLOS ONE.

Coralline algae are a type of red algae that helps build coral reef ecosystems in a variety of ways. They encourage reef growth by attracting coral larvae; they serve as a food source for reef animals; and help patch up broken coral skeletons by growing over breaks. The most important role of the algae when it comes to reef long term growth is directly reinforcing the limestone skeletons of corals with calcite, the hard mineral that forms the algae's skeleton. This allows coral reefs to maintain long-term structures that serve as the foundation of reef ecosystems.

Paleontologists think that the algae found in fossilized reefs plays a similar role in reef ecosystems as it does today. Weiss said that her study is the first to test that assumption by quantifying and statistically measuring that the algae has a significant, long term effect on reef diversity and structure.

Weiss research involved analyzing data from 128 fossilized coral reefs with coralline algae present cited in the research literature. She zeroed in specifically on reefs that were fossilized in the late Cretaceous and Cenozoic, a period that spans from 100 million years ago to the present.

She found that reefs with significant algae fortification were strongly associated with having higher structural integrity and more active ecosystems than those with little or no signs of algae -- a correlation that is also found in modern day coral reefs.

"Studying ancient events and ecosystems provide is important information about the modern world," Weiss said. "This work shows that the important interaction between corals and coralline algae isn't new, it goes back millions of years."

Today, climate change is warming ocean water and making it more acidic, putting stress on coral reefs around the world. Weiss said that other research indicates that the algae may be more vulnerable to the effects of climate change than coral, a finding that she said exemplifies the importance of learning more about algae's relationship with corals now and in the past.

"We know how important coralline algae are to reef building, so that could mean that coralline algae actually play a larger part than corals in determining whether a coral reef survives an ocean acidification event," Weiss said. "My research underscores the importance of coralline algae to coral reefs and confirms the antiquity of that importance."

Richard Aronson, an expert on the paleontology and ecology of marine communities and the department head of biological sciences at the Florida Institute of Technology, emphasized the importance of looking to ancient reefs -- and the factors that influenced their life cycles -- to understand reefs in the future.

Read more at Science Daily

New ancient sea reptile found in Germany, the earliest of its kind

Skull reconstruction of Lagenanectes richterae.

A previously unrecognized 132 million-year-old fossilized sea monster from northern Germany has been identified by an international team of researchers. Findings published in the Journal of Vertebrate Paleontology.

The bizarre sea creature was a plesiosaur, an extinct long-necked aquatic reptile resembling the popular image of the Loch Ness monster, which dominated the seas during the Age of Dinosaurs.

The remains of the eight-meter-long skeleton were collected in 1964 by private fossil collectors. The perfectly preserved bones were rescued from heavy machinery excavating a clay-pit at Sarstedt near Hannover.

Despite being discovered nearly half a century ago, a group of international scientists was only recently invited to study the specimen by the Lower Saxony State Museum in Hannover. "It was an honor to be asked to research the mysterious Sarstedt plesiosaur skeleton" says Sven Sachs from the Natural History Museum in Bielefeld, Germany, and lead author on the study. "It has been one of the hidden jewels of the museum, and even more importantly, has turned out to be new to science."

The new plesiosaur was named Lagenanectes richterae, literally meaning 'Lagena swimmer', after the medieval German name for the Leine River near Sarstedt. The species was named for Dr Annette Richter, Chief Curator of Natural Sciences at the Lower Saxony State Museum, who facilitated documentation of the fossil.

The skeleton of Lagenanectes includes most of the skull, which had a meshwork of long fang-like teeth, together with vertebrae, ribs and bones from the four flipper-like limbs.

"The jaws had some especially unusual features." says Dr Jahn Hornung a palaeontologist based in Hamburg and co-author on the paper. "Its broad chin was expanded into a massive jutting crest, and its lower teeth stuck out sideways. These probably served to trap small fish and squid that were then swallowed whole."

Internal channels in the upper jaws might have housed nerves linked to pressure receptors or electroreceptors on the outside of the snout that would have helped Lagenanectes to locate its prey.

The bones also showed evidence of chronic bacterial infection suggesting that the animal had suffered from a long-term disease that perhaps eventually claimed its life.

"The most important aspect of this new plesiosaur is that it is amongst the oldest of its kind" says Dr Benjamin Kear from the Museum of Evolution at Uppsala University in Sweden and senior author on the study. "It is one of the earliest elasmosaurs, an extremely successful group of globally distributed plesiosaurs that seem to have had their evolutionary origins in the seas that once inundated Western Europe."

Elasmosaurs had spectacularly long necks -- the longest of any vertebrate -- including up to 75 individual vertebrae. Not all of the neck vertebrae of Lagenanectes were recovered but it is estimated that around 40 or 50 must have originally been present.

Read more at Science Daily

Largest Ichthyosaurus was pregnant mother

Skeleton of Ichthyosaurus.

Scientists from the UK and Germany have discovered the largest Ichthyosaurus on record and found it was pregnant at the time of death.

The new specimen is estimated to be between 3 and 3.5 m long and is an adult female. Ichthyosaurs were a highly successful group of sea-going reptiles that became extinct about 90 million years ago. Often misidentified as swimming dinosaurs, these reptiles appeared before the first dinosaurs had evolved. The largest species of ichthyosaur grew to over 20 m in length.

The new specimen was originally discovered on the Somerset coast, during the mid-1990s, and is from the Early Jurassic, roughly 200 million years old. However, the specimen remained unstudied until it wound up in the collections of the Lower Saxony State Museum in Hannover, Germany.

Palaeontologist Sven Sachs of the Bielefeld Natural History Museum (Germany) first saw the specimen in August 2016, whilst on a routine visit. He informed University of Manchester palaeontologist and ichthyosaur expert, Dean Lomax, and together, the pair examined the new specimen in early 2017. They identified it as an example of an Ichthyosaurus somersetensis, a new species that Dean and another colleague, Prof. Judy Massare, had previously identified.

Dean said "It amazes me that specimens such as this [the biggest] can still be 'rediscovered' in museum collections. You don't necessarily have to go out in the field to make a new discovery. This specimen provides new insights into the size range of the species, but also records only the third example of an Ichthyosaurus known with an embryo. That's special"

The embryo is incomplete and preserves only a portion of the back bone, a forefin, ribs and a few other bones. The preserved string of vertebrae is less than 7 cm long. The bones of the embryo are not fully ossified, meaning that the embryo was still developing.

Another intriguing discovery the duo made was that the tail of this new specimen did not belong with the rest of the skeleton. A tail from another ichthyosaur had been added to the skeleton to make it appear more complete and visually appealing for display.

Sven added "It is often important to examine fossils with a very critical eye. Sometimes, as in this instance, specimens aren't exactly what they appear to be. However, it was not 'put together' to represent a fake, but simply for a better display specimen. But, if 'fake' portions remain undetected then scientists can fall foul to this, which results in false information presented in the published record.

"Specimens like this provide palaeontologists with important information about when these animals lived. Many examples of Ichthyosaurus are from historical collections and most do not have good geographical or geological records, but this specimen has it all. It may help to date other ichthyosaur fossils that currently have no information."

Read more at Science Daily

Galaxy 5 billion light-years away shows we live in a magnetic universe

Astronomers observed the magnetic field of a galaxy five billion light-years away. The galaxy provides important insight into how magnetism in the universe formed and evolved.

With the help of a gigantic cosmic lens, astronomers have measured the magnetic field of a galaxy nearly five billion light-years away. The achievement is giving them important new clues about a problem at the frontiers of cosmology -- the nature and origin of the magnetic fields that play an important role in how galaxies develop over time.

The scientists used the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to study a star-forming galaxy that lies directly between a more-distant quasar and Earth. The galaxy's gravity serves as a giant lens, splitting the quasar's image into two separate images as seen from Earth. Importantly, the radio waves coming from this quasar, nearly 8 billion light-years away, are preferentially aligned, or polarized.

"The polarization of the waves coming from the background quasar, combined with the fact that the waves producing the two lensed images traveled through different parts of the intervening galaxy, allowed us to learn some important facts about the galaxy's magnetic field," said Sui Ann Mao, Minerva Research Group Leader for the Max Planck Institute for Radio Astronomy in Bonn, Germany.

Magnetic fields affect radio waves that travel through them. Analysis of the VLA images showed a significant difference between the two gravitationally-lensed images in how the waves' polarization was changed. That means, the scientists said, that the different regions in the intervening galaxy affected the waves differently.

"The difference tells us that this galaxy has a large-scale, coherent magnetic field, similar to those we see in nearby galaxies in the present-day universe," Mao said. The similarity is both in the strength of the field and in its arrangement, with magnetic field lines twisted in spirals around the galaxy's rotation axis.

Since this galaxy is seen as it was almost five billion years ago, when the universe was about two-thirds of its current age, this discovery provides an important clue about how galactic magnetic fields are formed and evolve over time.

"The results of our study support the idea that galaxy magnetic fields are generated by a rotating dynamo effect, similar to the process that produces the Sun's magnetic field," Mao said. "However, there are other processes that might be producing the magnetic fields. To determine which process is at work, we need to go still farther back in time -- to more distant galaxies -- and make similar measurements of their magnetic fields," she added.

"This measurement provided the most stringent tests to date of how dynamos operate in galaxies," said Ellen Zweibel from the University of Wisconsin-Madison.

Read more at Science Dialy

Ice age era bones recovered from underwater caves in Mexico

This is a diver with a human skull, found in Hoyo Negro.

When the Panamanian land bridge formed around 3 million years ago, Southern Mexico was in the middle of a great biotic interchange of large animals from North and South America that crossed the continents in both directions. However, fossil animals from this time have been rare for the in-between environments of Central America and southern Mexico. Recently, a team technical cave divers are helping fill in this gap by discovering remains of large animals that once roamed the Yucatán Peninsula, during the end of the last Ice Age (around 13,000 years ago). Lead author, Dr. Blaine Schubert will present the team's findings at this year's annual meeting of the Society of Vertebrate Paleontology held this year in Calgary, Alberta (Canada) on Saturday, Aug. 26th at 9:00am.

The team of divers descended into the flooded passageways to an underground pit known as "Hoyo Negro" (Spanish for "Black Hole"), reaching down 180 ft (55 m) into the darkness. During the last Ice Age, sea level was much lower, and the prehistoric animals were able to walk to Hoyo Negro through horizontal passageways, only to fall into the inescapable pit within the cave. Divers have been photo-documenting the material before extraction, using re-breathing SCUBA equipment to prevent bubbles from disturbing the site. Dr. Blaine Schubert of East Tennessee State University, one of the lead researchers on the project says, "preservation of the fossil material is extraordinary, and will allow us to reconstruct various aspects of anatomy, evolutionary relationships, and behavior. The diversity of the fauna gives us an exciting new picture of this region in the midst of rapid climatic and environmental change."

Thus far the crew has recovered remains of three different giant ground sloths (including an entirely new species), short-faced bears, mountain lions, sabertooth cats, a bizarre relative of elephants called a gomphothere, tapirs, and even a human. "This represents the oldest and most complete early human skeleton in the Americas, and she co-existed with a variety of megafauna" says Schubert. "The remains of the short-faced bear Arctotherium are particularly significant, representing not only the most complete and abundant material from one location, but also the first evidence that they crossed from South America into North America." This fossil fauna is fleshing out a larger ecosystem for southern North America, which has typically been thought of as more of a bridge between landmasses than its own thriving community of local inhabitants. As the international collaboration of U.S. and Mexican researchers continues its work, the scientists hope to better understand the nature of this bridge and its own ecological complexities.

From Science Daily

Plant 'smells' insect foe, initiates defense

Goldenrod can detect a compound produced by gall-inducing flies, according to researchers.

It cannot run away from the fly that does it so much damage, but tall goldenrod can protect itself by first "smelling" its attacker and then initiating its defenses, according to an international team of researchers.

"We found another weapon in the arsenal of defenses that plants might employ against their herbivore attackers, in this case eavesdropping on a very specific chemical signal from an herbivore to detect its presence and prepare for future attack," said Anjel Helms, postdoctoral fellow in entomology, Penn State.

According to Helms, the gall-inducing flies (Eurosta solidaginis) are specialists that, in Pennsylvania, feed only on tall goldenrod (Solidago altissima). The male flies emit a blend of chemicals that is attractive to females. Once the females arrive and the eggs are fertilized, the females deposit their eggs within the stem of a goldenrod plant. After the eggs hatch, the larvae begin feeding on the tissue inside the stem. Chemicals in the saliva of the larvae are thought to cause the plant to grow abnormally and form a gall, or protective casing of plant tissue, around the larvae.

"The flies strongly reduce the plant's fitness by decreasing the number of seeds it produces, as well as the sizes of those seeds," said John Tooker, associate professor of entomology, Penn State. "That's because when the plant's tissues are damaged by the insect, it diverts its energy away from seed production and instead toward production of the gall."

Helms and her colleagues previously found that goldenrod plants exposed to chemicals from the male flies produced greater amounts of a defense chemical known as jasmonic acid when they were damaged by herbivores.

In their current study, the scientists aimed to identify the specific chemical compounds goldenrod plants are detecting and to determine how sensitive the plants are to the compounds. The researchers, including those at the U.S. Department of Agriculture, the University of Hamburg, Germany, and ETH Zurich, first identified the chemical compounds that make up the male fly's chemical emission. After identifying and quantifying the compounds in the male fly emission, the researchers exposed goldenrod plants to the individual compounds and examined their defense responses. They found that the plants responded most strongly to a compound in the blend called E,S-conophthorin.

"E,S-conophthorin is the most abundant compound emitted by the flies," said Helms. "The compound appears to provide a strong and reliable cue for the plants to detect."

Next, the team examined goldenrod's sensitivity to E,S-conophthorin by exposing plants to different concentrations of the compound and measuring their defense responses.

"We found that goldenrod plants are sensitive to even small concentrations of this compound," said Tooker. "This is significant because it likely means that the plant has a dedicated mechanism to perceive this compound. The results provide evidence that goldenrod can detect a single compound from the fly, supporting the idea that there is a tight co-evolutionary relationship between these two species.

In other words, over time, as the fly has adapted to take advantage of the plant, the plant has adapted to protect itself from the fly."

The findings appear in Nature Communications.

According to Tooker, the team's previous work was the first to demonstrate a plant "smelling" its herbivore, and its current work is the first to document exactly what compound the plants are detecting.

Read more at Science Daily

Endangered sharks, rays further threatened by global food markets

Shark fin soup.

A majority of shark fins and manta ray gills sold around the globe for traditional medicines come from endangered species, a University of Guelph study has revealed.

Using cutting-edge DNA barcoding technology, researchers found 71 per cent of dried fins and gills collected from markets and stores came from species listed as at-risk and therefore banned from international trade.

"Despite the controversy around shark fin soup and the fact that many of these species are threatened there is still a large market for shark fins and a growing demand for ray gill plates," said Dirk Steinke, integrative biology professor and member of the Centre for Biodiversity Genomics. "It's an area that until now has been hard to enforce because shark fins are dried and processed before they are sold making it difficult to identify the species."

Shark finning, or removing fins from live sharks, is illegal in Canada. Importing shark fins for sale is also illegal for species at-risk.

Published in Scientific Reports, the study was conducted with researchers from the Guy Harvey Research Institute and Save Our Seas Shark Research Centre at Nova Southeastern University in Florida.

Researchers collected 129 market samples in Canada, China and Sri Lanka representing 20 shark and ray species. Twelve of those species, including whale sharks, are listed as protected and illegal to trade under the Convention on International Trade in Endangered Species (CITES).

"We were surprised to find whale shark fins and gills were being sold," said Steinke. "This magnificent animal has been on the CITES Appendices since 2003."

Developed at U of G, DNA barcoding allows scientists to identify species of organisms using genetic material.

"DNA barcoding is an ideal tool when identifying dried samples or samples that have been processed," said Steinke. "It provides enforcement agencies with a method for detecting whether the fins and gills that are being sold are legal or illegal imported species."

About half of the world's 1,200 species of sharks and rays are listed as threatened by the International Union for Conservation of Nature including 20 that may not be traded internationally.

Read more at Science Daily