Ancient skull shows early 'baleen whale' had teeth

This image shows a life-like reconstruction of Llanocetus denticrenatus, an ancient 'baleen' whale.

Today's baleen whales (Mysticetes) support their massive bodies by filtering huge volumes of small prey from seawater using comb-like baleen in their mouths much like a sieve. But new evidence reported in the journal Current Biology on May 10 based on careful analysis of a 34-million-year-old whale skull from Antarctica -- the second-oldest "baleen" whale ever found -- suggests that early whales actually didn't have baleen at all. Their mouths were equipped instead with well-developed gums and teeth, which they apparently used to bite large prey.

"Llanocetus denticrenatus is an ancient relative of our modern gentle giants, like humpback and blue whales," says Felix Marx of the Royal Belgian Institute of Natural Sciences. "Unlike them, however, it had teeth, and probably was a formidable predator."

"Until recently, it was thought that filter feeding first emerged when whales still had teeth," adds R. Ewan Fordyce at the University of Otago in New Zealand. "Llanocetus shows that this was not the case."

Like modern whales, Llanocetus had distinctive grooves on the roof of its mouth, the researchers explain, which usually contain blood vessels that supply the baleen. In Llanocetus, however, those grooves cluster around tooth sockets, where baleen would have been useless and at risk of being crushed.

"Instead of a filter, it seems that Llanocetus simply had large gums and, judging from the way its teeth are worn, mainly fed by biting large prey," Marx says. "Even so, it was huge: at a total body length of around 8 meters, it rivals some living whales in size."

The findings suggest that large gums in whales like Llanocetus gradually became more complex over evolutionary time and, ultimately, gave rise to baleen. That transition probably happened only after the teeth had already been lost and whales had switched from biting to sucking in small prey -- as many whales and dolphins now do. Marx and Fordyce suggest that baleen most likely arose as a way to keep such small prey inside the mouth more effectively.

Soft tissues, including baleen, normally rot away, making it difficult to study their evolution. As a result, researchers must rely on indicators preserved on the bones, such as tell-tale grooves or lumps indicating the position of a muscle, or holes for the passage of particular blood vessels and nerves.

"Llanocetus presents a lucky combination, where the shape of the bones, small features suggesting the course of soft tissues, and tooth wear all combine to tell a clear story," Fordyce says. "Crucially, Llanocetus is also extremely old and lived at the very time when Mysticetes first appeared. As such, it provides a rare window into the earliest phase of their evolution."

In the new study, Fordyce and Marx found that the broad rostrum of Llanocetus had sharp, widely spaced teeth with marked tooth wear suggesting that they were used to bite and shear prey. As in living Mysticetes, the palate bears many grooves, which have commonly been interpreted as evidence for baleen. However, the researchers showed that those grooves instead converged on the bony tooth sockets, suggesting a peri-dental blood supply to well-developed gums, rather than racks of baleen.

The findings show that the evolution of filter feeding wasn't as straightforward as previously thought, the researchers say. They'd now like to sort out when filter feeding and baleen first evolved.

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How turning down the heat makes a baby turtle male

Viewed under the microscope, this image shows the immature sex organs of a developing turtle. Cells that will eventually give rise to either eggs or sperm are stained red. The center panel shows that silencing a key gene called Kdm6b transforms a turtle gonad that otherwise would have become a future testis (left) into a future ovary instead (right).

Boy or girl? For those who want to influence their baby's sex, superstition and folk wisdom offer no shortage of advice whose effectiveness is questionable at best -- from what to eat to when to make love. But some animals have a technique backed by scientific proof: In turtles and other reptiles, whether an egg hatches male or female depends on the temperature of its nest.

The phenomenon was first discovered in reptiles more than 50 years ago, but until now the molecular details were a mystery.

In a study published May 11 in the journal Science, researchers say they have finally identified a critical part of the biological "thermometer" that turns a developing turtle male or female.

According to a team at Duke University and Zhejiang Wanli University in China, the explanation lies not in the DNA sequence itself -- the A's, T's, C's and G's -- but in a molecule that affects how genes are expressed without altering the underlying genetic code.

"Temperature-dependent sex determination has been a puzzle for a really long time," said Blanche Capel, a cell biology professor at Duke who led the research. "This is the first functional evidence of a molecular link that connects temperature with sexual development."

Unlike humans and most other mammals, the sex of many turtles, lizards and alligators isn't determined by the chromosomes they inherit, but by ambient temperatures during a sensitive stage of development.

For a common pond and pet turtle called the red-eared slider, for example, eggs incubated at 32 degrees Celsius (nearly 88 Fahrenheit) produce all female hatchlings, while those kept at 26 degrees Celsius (79 Fahrenheit) hatch as males.

In the study, the researchers show that cooler egg incubation temperatures turn up a key gene called Kdm6b in the turtle's immature sex organs, or gonads. This in turn acts as a biological "on" switch, activating other genes that allow testes to develop.

To home in on the critical Kdm6b gene, the researchers took a group of freshly laid turtle eggs, incubated them at either 26 or 32 degrees Celsius, and looked for differences in the way genes were turned on in the turtles' gonads early in development -- before their fate as ovaries or testes has been decided.

In a previous study, researchers examined all the gene readouts, or transcripts, produced in the turtles' gonads over this critical time window.

They found several genes that were turned up or down at one temperature but not the other. But one of the first genes to shift was one called Kdm6b, which became much more active at the cooler incubation temperatures that produce males, and was almost silent at warmer, female-producing temperatures.

In the new study, the team used a technique developed by collaborators at Zhejiang Wanli University to suppress the Kdm6b gene in turtle gonads and see how it affects their sexual development.

Silencing the Kdm6b gene, they found, transforms a growing turtle embryo kept at temperatures that would otherwise produce a male with testes into a baby female with ovaries instead.

Further experiments showed that the protein encoded by the Kdm6b gene in turn interacts with a region of the genome called Dmrt1, which acts as a master switch to turn on testis development.

They found that Kdm6b activates the Dmrt1 master switch by modifying histones, the ball-like proteins that DNA is wrapped around inside the cell nucleus, like thread wound around a spool.

In many species, the tail of histone proteins is decorated with special chemical markers, or methyl tags, that keep genes along the DNA molecule inactive.

Kdm6b gene activity turns on the Dmrt1 master switch by removing these repressive tags and "loosening" the histone tails, which makes the DNA wound around the histones easier to access and read.

"It's like removing the brakes off the male pathway," said co-author Ceri Weber, a PhD candidate in the Capel lab at Duke.

Researchers have found temperature-related shifts in Kdm6b gene activity in other species whose sex depends on incubation temperature, such as alligators and bearded dragons. "This suggests that similar molecular mechanisms may be at work in other reptiles too," Capel said.

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Jurassic fossil tail tells of missing link in crocodile family tree

Pelvis fragments.

A 180-million-year-old fossil has shed light on how some ancient crocodiles evolved into dolphin-like animals.

The specimen -- featuring a large portion of backbone -- represents a missing link in the family tree of crocodiles, and was one of the largest coastal predators of the Jurassic Period, researchers say.

The newly discovered species was nearly five metres long and had large, pointed teeth for grasping prey. It also shared key body features seen in two distinct families of prehistoric crocodiles, the team says.

Some Jurassic-era crocodiles had bony armour on their backs and bellies, and limbs adapted for walking on land. Another group had tail fins and flippers but did not have armour.

The new species was heavily armoured but also had a tail fin, suggesting it is a missing link between the two groups, researchers say.

It has been named Magyarosuchus fitosi in honour of the amateur collector who discovered it, Attila Fitos.

The fossil -- unearthed on a mountain range in north-west Hungary in 1996 and stored in a museum in Budapest -- was examined by a team of palaeontologists, including a researcher from the University of Edinburgh.

It was identified as a new species based on the discovery of an odd-looking vertebra that formed part of its tail fin.

The study, published in the journal PeerJ, also involved researchers in Hungary and Germany. It was supported by the Leverhulme Trust and the SYNTHESYS project, part of the European Commission's Seventh Framework Programme.

Dr Mark Young, of the University of Edinburgh's School of GeoSciences, who was involved in the study, said: "This fossil provides a unique insight into how crocodiles began evolving into dolphin and killer whale-like forms more than 180 million years ago. The presence of both bony armour and a tail fin highlights the remarkable diversity of Jurassic-era crocodiles."

From Science Daily

Neuroscientists find first evidence animals can mentally replay past events

To test the rats' memory, IU researchers placed the animals inside an "arena" with different odors. The rats were rewarded when they identified the second-to-last item or fourth-to-last odor from a list of unpredictable length.

Neuroscientists at Indiana University have reported the first evidence that non-human animals can mentally replay past events from memory. The discovery could help advance the development of new drugs to treat Alzheimer's disease.

The study, led by IU professor Jonathon Crystal, appears today in the journal Current Biology.

"The reason we're interested in animal memory isn't only to understand animals, but rather to develop new models of memory that match up with the types of memory impaired in human diseases such as Alzheimer's disease," said Crystal, a professor in the IU Bloomington College of Arts and Sciences' Department of Psychological and Brain Sciences and director of the IU Bloomington Program in Neuroscience.

Under the current paradigm, Crystal said most preclinical studies on potential new Alzheimer's drugs examine how these compounds affect spatial memory, one of the easiest types of memory to assess in animals. But spatial memory is not the type of memory whose loss causes the most debilitating effects of Alzheimer's disease.

"If your grandmother is suffering from Alzheimer's, one of the most heartbreaking aspects of the disease is that she can't remember what you told her about what's happening in your life the last time you saw her," said Danielle Panoz-Brown, an IU Ph.D. student who is the first author on the study. "We're interested in episodic memory -- and episodic memory replay -- because it declines in Alzheimer's disease, and in aging in general."

Episodic memory is the ability to remember specific events. For example, if a person loses their car keys, they might try to recall every single step -- or "episode" -- in their trip from the car to their current location. The ability to replay these events in order is known as "episodic memory replay." People wouldn't be able to make sense of most scenarios if they couldn't remember the order in which they occurred, Crystal said.

To assess animals' ability to replay past events from memory, Crystal's lab spent nearly a year working with 13 rats, which they trained to memorize a list of up to 12 different odors. The rats were placed inside an "arena" with different odors and rewarded when they identified the second-to-last odor or fourth-to-last odor in the list.

The team changed the number of odors in the list prior to each test to confirm the odors were identified based upon their position in the list, not by scent alone, proving the animals were relying on their ability to recall the whole list in order. Arenas with different patterns were used to communicate to the rats which of the two options was sought.

After their training, Crystal said, the animals successfully completed their task about 87 percent of the time across all trials. The results are strong evidence the animals were employing episodic memory replay.

Additional experiments confirmed the rats' memories were long-lasting and resistant to "interference" from other memories, both hallmarks of episodic memory. They also ran tests that temporarily suppressed activity in the hippocampus -- the site of episodic memory -- to confirm the rats were using this part of their brain to perform their tasks.

Crystal said the need to find reliable ways to test episodic memory replay in rats is urgent since new genetic tools are enabling scientists to create rats with neurological conditions similar to Alzheimer's disease. Until recently, only mice were available with the genetic modifications needed to study the effect of new drugs on these symptoms.

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Rapid evolution fails to save butterflies from extinction in face of human-induced change

This is an Edith's checkerspot butterfly (Euphydryas editha) on a narrow-leaved plantain (Plantago lanceolata).

The evolution of wild species, adapting them to human management practices, can cause localised extinctions when those practices rapidly change. And in a new study published in Nature, Professors Michael C. Singer and Camille Parmesan have used more than 30 years of research to fully document an example of this process.

A large, isolated population of a North American butterfly evolved complete dependence on an introduced European weed to the point where the continued existence of the butterfly depended on the plant's availability. The insects then became locally extinct when humans effectively eliminated that availability, confirming a prediction made by the same authors in a 1993 Nature paper.

Thus the advent of cattle ranching more than 100 years ago set an eco-evolutionary trap that the insects obligingly fell into, and the trap was sprung when humans suddenly removed the cattle, withdrawing their 'gift', and driving the butterflies to extinction.

European conservation biologists have long believed this to be the process underlying many local extinctions across Europe, and this study provides the first hard evidence of the process in action in real time. It also foreshadows an increasing importance of maintaining historical land use practices, including cattle ranching, as conservation measures in North America.

The authors, affiliated to the University of Plymouth, the University of Texas at Austin and CNRS Moulis, have spent more than three decades studying changes in the diet of Edith's checkerspot (Euphydryas editha) in a spring-fed meadow surrounded by semi-desert sagebrush and pine forest on a family-run ranch in Nevada.

In particular, the authors assessed the impact of narrow-leaved plantain (Plantago lanceolata), which was introduced to the USA in hay brought from Europe and flourished under cattle-grazing, probably arriving in Nevada more than 100 years ago.

As soon as the butterflies encountered the plantain, their caterpillars survived better on it than on their traditional host, Blue-Eyed Mary (Collinsia parviflora), causing the adults to evolve preference for laying eggs on the plantain. By the mid-2000s, they were 100% reliant on the plantain and the Collinsia had been abandoned.

However, within three years of the ranch's cattle being removed due to financial pressures, the butterflies became locally extinct as the grasses around their favoured new host were no longer grazed, and the plantains became embedded in those grasses, cooling the micro-environment. The Collinsia was unaffected by removal of cattle, so if the butterflies had not evolved so rapidly in response to the introduction of the plantain, they would most likely have survived.

Around five years after the extinction, Edith's checkerspots recolonized the meadow. Since they were all found feeding on Collinsia, the original host plant, scientists believe these colonists to be a new population, and that the lineage which had called the ranch home for several decades no longer exists.

They say the results are similar to that seen in British species such as the large blue butterfly, which went extinct across southern England following a reduction of grazing by both rabbits and sheep. Once this process was understood, the butterflies could be successfully re-introduced.

Professor Singer, who has been studying the diet of Edith's checkerspot for more than 50 years and led the current study, said: "This is a clear example of how humans are able to change habitats faster than even rapidly-evolving species can change their behaviour. This cannot be not an isolated phenomenon, so unless we become aware of the potential consequences of such actions we will continue to inadvertently cause population extinctions of native species, without recognizing what we are doing. Species-level extinctions are possible when human activities are synchronized across wide areas."

Professor Parmesan, a lead contributor to the Intergovernmental Panel on Climate Change which was awarded the Nobel Peace Prize in 2007, said the study had potentially wider implications beyond the scope of changes to farming practices.

Read more at Science Daily

500-year-old Leaning Tower of Pisa mystery unveiled by engineers

Leaning tower of Pisa, Italy.

Why has the Leaning Tower of Pisa survived the strong earthquakes that have hit the region since the middle ages? This is a long-standing question a research group of 16 engineers has investigated, including a leading expert in earthquake engineering and soil-structure interaction from the University of Bristol.

Professor George Mylonakis, from Bristol's Department of Civil Engineering, was invited to join a 16-member research team, led by Professor Camillo Nuti at Roma Tre University, to explore this Leaning Tower of Pisa mystery that has puzzled engineers for many years.

Despite leaning precariously at a five-degree angle, leading to an offset at the top of over five metres, the 58-metre tall Tower has managed to survive, undamaged, at least four strong earthquakes that have hit the region since 1280.

Given the vulnerability of the structure, which barely manages to stand vertically, it was expected to sustain serious damage or even collapse because of moderate seismic activity. Surprisingly this hasn't happened and until now this has mystified engineers for a long time. After studying available seismological, geotechnical and structural information, the research team concluded that the survival of the Tower can be attributed to a phenomenon known as dynamic soil-structure interaction (DSSI).

The considerable height and stiffness of the Tower combined with the softness of the foundation soil, causes the vibrational characteristics of the structure to be modified substantially, in such a way that the Tower does not resonate with earthquake ground motion. This has been the key to its survival. The unique combination of these characteristics gives the Tower of Pisa the world record in DSSI effects.

Professor Mylonakis, Chair in Geotechnics and Soil-Structure Interaction, and Head of Earthquake and Geotechnical Engineering Research Group in the Department of Civil Engineering at the University of Bristol, said: "Ironically, the very same soil that caused the leaning instability and brought the Tower to the verge of collapse, can be credited for helping it survive these seismic events."

Results from the study have been presented to international workshops and will be formally announced at the 16th European Conference in Earthquake Engineering taking place in Thessaloniki, Greece next month [18 to 21 June 2018].

From Science Daily

New research shows how Indo-European languages spread across Asia

Przewalskii horse herd grazing on pasture

A new study has discovered that horses were first domesticated by descendants of hunter-gatherer groups in Kazakhstan who left little direct trace in the ancestry of modern populations. The research sheds new light on the long-standing "steppe theory" on the origin and movement of Indo-European languages made possible by the domestication of the horse.

The domestication of the horse was a milestone in human history that allowed people, their languages, and their ideas to move further and faster than before, leading both to widespread farming and to horse-powered warfare.

Scholars from around the world have collaborated on a new inter-disciplinary research project, which was published in the journal Science 9 May 2018. The researchers analysed ancient and modern DNA samples from humans and compared the results -- the 74 ancient whole-genome sequences studied by the group were up to 11,000 years old and were from inner Asia and Turkey.

Professor Eske Willerslev, who holds positions both at St John's College, University of Cambridge, and the University of Copenhagen, jointly led the study which looked at archaeological findings, history, and linguistics.

Much of the study builds on questions raised by scholars of Indo-European studies at the Institute of Nordic Studies and Linguistics at University of Copenhagen. A number of conflicting theories have been presented about who first domesticated the horse, with previous studies pointing to people of the pastoralist Yamnaya culture, a dominant herding group who lived in Eastern Europe and Western Asia.

Dr. Guus Kroonen, historical linguist at University of Copenhagen, explains:

"The successful spread of the Indo-European languages across Eurasia has puzzled researchers for a century. It was thought that speakers of this language family played a key role in the domestication of the horse, and that this, in combination with the development of wheeled vehicles, allowed them to spread across Eurasia from the Yamnaya culture."

However, as this study shows, domesticated horses were used by the Botai people already 5,500 years ago, and much further East in Central Asia, completely independent of the Yamnaya pastoralists. A further twist to the story is that the descendants of these Botai were later pushed out from the central steppe by migrations coming from the west. Their horses were replaced too, indicating that horses were domesticated separately in other regions as well.

No link between Botai and Yamnaya cultures

The study does not find a genetic link between the people associated with the Yamnaya and Botai archaeological cultures, which is critical to understanding the eastward movement of the Yamnaya. Apparently, their eastward expansion bypassed the Botai completely, moving 3000 kilometres across the steppe to the Altai Mountains in Central and East Asia.

Professor Alan Outram from the Department of Archaeology at the University of Exeter and one of the paper's authors, states:

"We now know that the people who first domesticated the horse in Central Asia were the descendants of ice age hunters, who went on to become the earliest pastoralists in the region. Despite their local innovations, these peoples were overrun and replaced by European steppe pastoralists in the middle and later Bronze Age, and their horses were replaced too."

Languages spread through exchanges between several cultures

The authors also demonstrate the oldest known Indo-European language, Hittite, did not result from a massive population migration from the Eurasian Steppe as previously claimed.

In contrast to a series of recent studies on population movement in Europe during the Bronze Age, the new results from Asia suggest that population and language spread across the region is better understood by groups of people mixing together.

Gojko Barjamovic, Senior Lecturer on Assyriology at Harvard University, explains:

"In Anatolia, and parts of Central Asia, which held densely settled complex urban societies, the history of language spread and genetic ancestry is better described in terms of contact and absorption than by simply a movement of population."

He adds:

"The Indo-European languages are usually said to emerge in Anatolia in the 2nd millennium BCE. However, we use evidence from the palatial archives of the ancient city of Ebla in Syria to argue that Indo-European was already spoken in modern-day Turkey in the 25th century BCE. This means that the speakers of these language must have arrived there prior to any Yamnaya expansions."

The study also shows that the spread of the Indo-Iranian languages to South Asia, with Hindi, Urdu and Persian as major modern offshoots, cannot result from the Yamnaya expansions. Rather, the Indo-Iranian languages spread with a later push of pastoralist groups from the South Ural Mountains during the Middle to Late Bronze Age.

Prior to entering South Asia, these groups, thought to have spoken an Indo-Iranian language, were impacted by groups with an ancestry typical of more western Eurasian populations. This suggests that the Indo-Iranian speakers did not split off from the Yamnaya population directly, but were more closely related to the Indo-European speakers that lived in Eastern Europe.

Unique collaboration between the humanities and the natural sciences

In this study, geneticists, historians, archaeologists and linguists find common ground -- pointing to increased interaction between the steppe and the Indus Valley during the Late Bronze Age as the most plausible time of entry of Indo-European languages in South Asia. Several authors of the paper had radically conflicting views before the final interpretation was achieved.

Lead author on the article, Peter de Barros Damgaard, who is a geneticist working at the University of Copenhagen comments:

"The project has been an extremely enriching and exciting process. We were able to direct many very different academic fields towards a single coherent approach. By asking the right questions, and keeping limitations of the data in mind, contextualizing, nuancing, and keeping dialogues open between scholars of radically different backgrounds and approaches, we have carved out a path for a new field of research. We have already seen too many papers come out in which models produced by geneticists working on their own have been are accepted without vital input from other fields, and, at the other extreme, seen archaeologists opposing new studies built on archaeogenetic data, due to a lack of transparency between the fields."

"Data on ancient DNA is astonishing for its ability to provide a fine-grained image of early human mobility, but it does stand on the shoulders of decades of work by scholars in other fields, from the time of excavation of human skeletons to interpreting the cultural, linguistic origins of the samples. This is how cold statistics are turned into history."

Read more at Science Daily

Stone Age hepatitis B virus decoded

Skeletal remains of HBV positive individual from the Stone Age site of Karsdorf, Germany. The individual was a male with an age at death of around 25-30 years.

An international team of scientists led by researchers at the Max Planck Institute for the Science of Human History and the University of Kiel has successfully reconstructed genomes from Stone Age and Medieval European strains of the hepatitis B virus. This unprecedented recovery of ancient virus DNA indicates that hepatitis B was circulating in Europe at least 7000 years ago. While the ancient virus is similar to its modern counterparts, the strains represent a distinct lineage that has likely gone extinct and is most closely related to chimpanzee and gorilla viruses.

The hepatitis B virus (HBV) is one of the most widespread human pathogens known today, affecting over 250 million people worldwide. However, its origin and evolutionary history remain unclear. Studying the evolution and history of the virus has to date been especially difficult, because until now viral DNA had not been successfully recovered from prehistoric samples. In the present study, which has been accepted for publication in the journal eLife and is due to be published on May 10, 2018, an international team of researchers led by the Max Planck Institute for the Science of Human History and the Institute of Clinical Molecular Biology at Kiel University, not only recovered ancient viral DNA from skeletons but also reconstructed the genomes of three strains of HBV.

The ancient history of hepatitis B

For this study, the researchers analyzed samples from the teeth of 53 skeletons excavated from Neolithic and medieval sites in Germany. The remains dated from around 5000 BC to 1200 AD. The researchers screened all samples for viral pathogens and detected ancient HBV in three of the individuals. Full HBV genomes were recovered from these samples, two of which were from the Neolithic period, dating to about 7000 and 5000 years ago, and one from the medieval period. The Neolithic genomes represent the by far oldest virus genomes reconstructed to date.

Interestingly, the ancient virus genomes appear to represent distinct lineages that have no close relatives today and possibly went extinct. The two Neolithic genomes, although recovered from individuals that lived 2000 years apart, were relatively similar to each other in comparison with modern strains, and were in fact more closely related to modern strains of HBV found in Chimpanzees and Gorillas. In contrast, the medieval HBV genome is more similar to modern strains, but still represents a separate lineage. This is the case even when it is compared to two previously published HBV genomes recovered from mummies dating to the 16th century. The HBV strains found in these mummies are closely related to modern strains, suggesting a surprising lack of change in the virus over the last 500 years. These findings point to a complicated history for the virus, which may have involved multiple cross-species transmission events.

Long and complicated evolution of one of today's most common viruses

"Taken together, our results demonstrate that HBV already existed in Europeans 7000 years ago and that its genomic structure closely resembled that of modern hepatitis B viruses, despite the differences observed," explains first author Ben Krause-Kyora, of the Max Planck Institute for the Science of Human History and Kiel University. "More ancient precursors, intermediates and modern strains of both human and non-human primate HBV strains need to be sequenced to disentangle the complex evolution of this virus," he adds.

Read more at Science Daily

New magnetic process in turbulent space

In this visualization, as the supersonic solar wind (yellow haze) flows around the Earth's magnetic field (blue wavy lines), it forms a highly turbulent boundary layer called the 'magnetosheath' (yellow swirling area). A new research paper describes observations of small-scale magnetic reconnection within the magnetosheath, revealing important clues about heating in the sun's outer layers and elsewhere in the universe.

Though close to home, the space immediately around Earth is full of hidden secrets and invisible processes. In a new discovery reported in the journal Nature, scientists working with NASA's Magnetospheric Multiscale spacecraft -- MMS -- have uncovered a new type of magnetic event in our near-Earth environment by using an innovative technique to squeeze extra information out of the data.

Magnetic reconnection is one of the most important processes in the space -- filled with charged particles known as plasma -- around Earth. This fundamental process dissipates magnetic energy and propels charged particles, both of which contribute to a dynamic space weather system that scientists want to better understand, and even someday predict, as we do terrestrial weather. Reconnection occurs when crossed magnetic field lines snap, explosively flinging away nearby particles at high speeds. The new discovery found reconnection where it has never been seen before -- in turbulent plasma.

"In the plasma universe, there are two important phenomena: magnetic reconnection and turbulence," said Tai Phan, a senior fellow at the University of California, Berkeley, and lead author on the paper. "This discovery bridges these two processes."

Magnetic reconnection has been observed innumerable times in the magnetosphere -- the magnetic environment around Earth -- but usually under calm conditions. The new event occurred in a region called the magnetosheath, just outside the outer boundary of the magnetosphere, where the solar wind is extremely turbulent. Previously, scientists didn't know if reconnection even could occur there, as the plasma is highly chaotic in that region. MMS found it does, but on scales much smaller than previous spacecraft could probe.

MMS uses four identical spacecraft flying in a pyramid formation to study magnetic reconnection around Earth in three dimensions. Because the spacecraft fly incredibly close together -- at an average separation of just four-and-a-half miles, they hold the record for closest separation of any multi-spacecraft formation -- they are able to observe phenomena no one has seen before. Furthermore, MMS's instruments are designed to capture data at speeds a hundred times faster than previous missions.

Even though the instruments aboard MMS are incredibly fast, they are still too slow to capture turbulent reconnection in action, which requires observing narrow layers of fast moving particles hurled by the recoiling field lines. Compared to standard reconnection, in which broad jets of ions stream out from the site of reconnection, turbulent reconnection ejects narrow jets of electrons only a couple miles wide.

"The smoking gun evidence is to measure oppositely directed electron jets at the same time, and the four MMS spacecraft were lucky to corner the reconnection site and detect both jets," said Jonathan Eastwood, a lecturer at Imperial College, London, and a co-author of the paper.

Crucially, MMS scientists were able to leverage the design of one instrument, the Fast Plasma Investigation, to create a technique to interpolate the data -- essentially allowing them to read between the lines and gather extra data points -- in order to resolve the jets.

"The key event of the paper happens in only 45 milliseconds. This would be one data point with the basic data," said Amy Rager, a graduate student at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the scientist who developed the technique. "But instead we can get six to seven data points in that region with this method, allowing us to understand what is happening."

With the new method, the MMS scientists are hopeful they can comb back through existing datasets to find more of these events, and potentially other unexpected discoveries as well.

Read more at Science Daily

'Snowball Earth' resulted from plate tectonics

During its 'snowball' phase, the Earth may have resembled Enceladus, a moon of Saturn that is covered in snow and ice.

About 700 million years ago, the Earth experienced unusual episodes of global cooling that geologists refer to as "Snowball Earth."

Several theories have been proposed to explain what triggered this dramatic cool down, which occurred during a geological era called the Neoproterozoic. Now two geologists at The University of Texas at Dallas and UT Austin suggest that those major climate changes can be linked to one thing: the advent of plate tectonics.

The research was published online in December 2017 and in the April print edition of the journal Terra Nova.

Plate tectonics is a theory formulated in the late 1960s that states the Earth's crust and upper mantle -- a layer called the lithosphere -- is broken into moving pieces, or plates. These plates move very slowly -- about as fast as your fingernails and hair grow -- causing earthquakes, mountain ranges and volcanoes.

"Earth is the only body in our solar system known to currently have plate tectonics, where the lithosphere is fragmented like puzzle pieces that move independently," said Dr. Robert Stern, professor of geosciences in UT Dallas' School of Natural Sciences and Mathematics, and co-author of the study, along with Dr. Nathaniel Miller, a research scientist in UT Austin's Jackson School of Geosciences who earned his PhD in geosciences from UT Dallas in 1995.

"It is much more common for planets to have an outer solid shell that is not fragmented, which is known as 'single lid tectonics'," Stern said.

Geoscientists disagree about when the Earth changed from single lid to plate tectonics, with the plate fragmenting from one plate to two plates and so on to the present global system of seven major and many smaller plates. But Stern highlights geological and theoretical evidence that plate tectonics began between 800 million and 600 million years ago, and has published several articles arguing for this timing.

In the new study, Stern and Miller provide new insights by suggesting that the onset of plate tectonics likely initiated the changes on Earth's surface that led to Snowball Earth. They argue that plate tectonics is the event that can explain 22 theories that other scientists have advanced as triggers of the Neoproterozoic Snowball Earth.

"We went through the literature and examined all the mechanisms that have been put forward for Snowball Earth," Stern said. "The start of plate tectonics could be responsible for each of these explanations."

The onset of plate tectonics should have disturbed the oceans and the atmosphere by redistributing continents, increasing explosive arc volcanism and stimulating mantle plumes, Stern said.

"The fact that strong climate and oceanographic effects are observed in the Neoproterozoic time is a powerful supporting argument that this is indeed the time of the transition from single lid to plate tectonics," Stern said. "It's an argument that, to our knowledge, hasn't yet been considered.

Read more at Science Daily