Tracking down the asteroid that sealed the fate of the dinosaurs

Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analysed samples of the rock layer that marks the boundary between the Cretaceous and Paleogene periods. This period also saw the last major mass extinction event on Earth, in which around 70 percent of all animal species became extinct. The results of the study published in Science indicate that the asteroid formed outside Jupiter's orbit during the early development of our solar system.

According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least 10 kilometres in diameter near Chicxulub on the Yucatán Peninsula in Mexico.

On impact, the asteroid and large quantities of earth rock vaporized.

Fine dust particles spread into the stratosphere and obscured the sun.

This led to dramatic changes in the living conditions on the planet and brought photosynthetic activity to a halt for several years.

The dust particles released by the impact formed a layer of sediment around the entire globe.

This is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth.

It contains high concentrations of platinum-group metals, which come from the asteroid and are otherwise extremely rare in the rock that forms the Earth's crust.

By analysing the isotopic composition of the platinum metal ruthenium in the cleanroom laboratory of the University of Cologne's Institute of Geology and Mineralogy, the scientists discovered that the asteroid originally came from the outer solar system.

"The asteroid's composition is consistent with that of carbonaceous asteroids that formed outside of Jupiter's orbit during the formation of the solar system," said Dr Mario Fischer-Gödde, first author of the study.

The ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth for comparison. This data shows that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system. Professor Dr Carsten Münker, co-author of the study, added: "We found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in geological time. The fate of the dinosaurs and many other species was sealed by this projectile from the outer reaches of the solar system."

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New snake discovery rewrites history, points to North America's role in snake evolution

A new species of fossil snake unearthed in Wyoming is rewriting our understanding of snake evolution. The discovery, based on four remarkably well-preserved specimens found curled together in a burrow, reveals a new species named Hibernophis breithaupti. This snake lived in North America 34 million years ago and sheds light on the origin and diversification of boas and pythons.

Hibernophis breithaupti has unique anatomical features, in part because the specimens are articulated -- meaning they were found all in one piece with the bones still arranged in the proper order -- which is unusual for fossil snakes.

Researchers believe it may be an early member of Booidea, a group that includes modern boas and pythons.

Modern boas are widespread in the Americas, but their early evolution is not well understood.These new and very complete fossils add important new information, in particular, on the evolution of small, burrowing boas known as rubber boas.

Traditionally, there has been much debate on the evolution of small burrowing boas.

Hibernophis breithaupti shows that northern and more central parts of North America might have been a key hub for their development.

The discovery of these snakes curled together also hints at the oldest potential evidence for a behavior familiar to us today -- hibernation in groups.

"Modern garter snakes are famous for gathering by the thousands to hibernate together in dens and burrows," says Michael Caldwell, a U of A paleontologist who co-led the research along with his former graduate student Jasmine Croghan, and collaborators from Australia and Brazil. "They do this to conserve heat through the effect created by the ball of hibernating animals. It's fascinating to see possible evidence of such social behavior or hibernation dating back 34 million years."

From Science Daily

Origins of creativity in the brain

Have you ever had the solution for a tough problem suddenly hit you when you're thinking about something entirely different? Creative thought is a hallmark of humanity, but it's an ephemeral, almost paradoxical ability, striking unexpectedly when it's not sought out.

And the neurological source of creativity -- what's going on in our brains when we think outside the box -- is similarly elusive.

But now, a research team led by a University of Utah Health researcher and based in Baylor College of Medicine has used a precise method of brain imaging to unveil how different parts of the brain work together in order to produce creative thought.

Their findings published in BRAIN on June 18.

The new results could ultimately help lead to interventions that spark creative thought or aid people who have mental illnesses that disrupt these regions of the brain.

Outside the bo

Higher cognitive processes like creativity are especially hard to study. "Unlike motor function or vision, they're not dependent on one specific location in the brain," says Ben Shofty, MD, PhD, assistant professor of neurosurgery in the Spencer Fox Eccles School of Medicine and senior author on the paper. "There's not a creativity cortex."

But there's evidence that creativity is a distinct brain function. Localized brain injury caused by stroke can lead to changes in creative ability -- both positive and negative. That discovery suggests that narrowing down the neurological basis of creativity is possible.

Shofty suspected that creative thought might rely strongly on parts of the brain that are also activated during meditation, daydreaming, and other internally focused types of thinking. This network of brain cells is the default mode network (DMN), so called because it's associated with the "default" patterns of thought that happen in the absence of specific mental tasks. "Unlike most of the functions that we have in the brain, it's not goal-directed," Shofty says. "It's a network that basically operates all the time and maintains our spontaneous stream of consciousness."

The DMN is spread out across many dispersed brain regions, making it more difficult to track its activity in real time. The researchers had to use an advanced method of brain activity imaging to understand what the network was doing moment-to-moment during creative thought. In a strategy most commonly used to pinpoint the location of seizures in patients with severe epilepsy, tiny electrodes are implanted in the brain to precisely track the electrical activity of multiple brain regions.

Participants in the study were already undergoing this kind of seizure monitoring, which meant that the research team could also use the electrodes to measure brain activity during creative thinking. This provided a much more detailed picture of the neural basis of creativity than researchers had been able to capture before. "We could see what's happening within the first few milliseconds of attempting to perform creative thinking,"Shofty says.

Two steps toward originality

The researchers saw that during a creative thinking task in which participants were asked to list novel uses for an everyday item, like a chair or a cup, the DMN lit up with activity first. Then, its activity synchronized with other regions in the brain, including ones involved in complex problem-solving and decision-making. Shofty believes this means that creative ideas originate in the DMN before being evaluated by other regions.

What's more, the researchers were able to show that parts of the network are required specifically for creative thought. When the researchers used the electrodes to temporarily dampen the activity of particular regions of the DMN, people brainstormed uses for the items they saw that were less creative. Their other brain functions, like mind wandering, remained perfectly normal.

Eleonora Bartoli, PhD, assistant professor of neurosurgery at Baylor College of Medicine and co-first author on the paper, explains that this result shows that creativity isn't just associated with the network but fundamentally depends on it. "We moved beyond correlational evidence by using direct brain stimulation," she says. "Our findings highlight the causal role of the DMN in creative thinking."

The activity of the network is changed in several disorders, such as ruminative depression, in which the DMN is more active than normal, possibly related to increased dwelling on negative internally directed thoughts. Shofty says that a better understanding of how the network operates normally may lead to better treatments for people with such conditions.

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Parkinson's Disease: New theory on the disease's origins and spread

The nose or the gut? For the past two decades, the scientific community has debated the wellspring of the toxic proteins at the source of Parkinson's disease. In 2003, a German pathologist, Heiko Braak, MD, first proposed that the disease begins outside the brain. More recently, Per Borghammer, MD, with Aarhus University Hospital in Denmark, and his colleagues argue that the disease is the result of processes that start in either the brain's smell center (brain-first) or the body's intestinal tract (body-first).

A new hypothesis paper appearing in the Journal of Parkinson's Disease on World Parkinson's Day unites the brain- and body-first models with some of the likely causes of the disease-environmental toxicants that are either inhaled or ingested. The authors of the new study, who include Borghammer, argue that inhalation of certain pesticides, common dry cleaning chemicals, and air pollution predispose to a brain-first model of the disease. Other ingested toxicants, such as tainted food and contaminated drinking water, lead to body-first model of the disease.

"In both the brain-first and body-first scenarios the pathology arises in structures in the body closely connected to the outside world," said Ray Dorsey, MD, a professor of Neurology at the University of Rochester Medical Center and co-author of the piece. "Here we propose that Parkinson's is a systemic disease and that its initial roots likely begin in the nose and in the gut and are tied to environmental factors increasingly recognized as major contributors, if not causes, of the disease. This further reinforces the idea that Parkinson's, the world's fastest growing brain disease, may be fueled by toxicants and is therefore largely preventable."

Different pathways to the brain, different forms of disease

A misfolded protein called alpha-synuclein has been in scientists' sights for the last 25 years as one of the driving forces behind Parkinson's. Over time, the protein accumulates in the brain in clumps, called Lewy bodies, and causes progressive dysfunction and death of many types of nerve cells, including those in the dopamine-producing regions of the brain that control motor function. When first proposed, Braak thought that an unidentified pathogen, such as a virus, may be responsible for the disease.

The new piece argues that toxins encountered in the environment, specifically the dry cleaning and degreasing chemicals trichloroethylene (TCE) and perchloroethylene (PCE), the weed killer paraquat, and air pollution, could be common causes for the formation of toxic alpha-synuclein. TCE and PCE contaminates thousands of former industrial, commercial, and military sites, most notably the Marine Corps base Camp Lejeune, and paraquat is one of the most widely used herbicides in the US, despite being banned for safety concerns in more than 30 countries, including the European Union and China. Air pollution was at toxic levels in nineteenth century London when James Parkinson, whose 269th birthday is celebrated today, first described the condition.

The nose and the gut are lined with a soft permeable tissue, and both have well established connections to the brain. In the brain-first model, the chemicals are inhaled and may enter the brain via the nerve responsible for smell. From the brain's smell center, alpha-synuclein spreads to other parts of the brain principally on one side, including regions with concentrations of dopamine-producing neurons. The death of these cells is a hallmark of Parkinson's disease. The disease may cause asymmetric tremor and slowness in movement and, a slower rate of progression after diagnosis, and only much later, significant cognitive impairment or dementia.

When ingested, the chemicals pass through the lining of the gastrointestinal tract. Initial alpha-synuclein pathology may begin in the gut's own nervous system from where it can spread to both sides of the brain and spinal cord. This body-first pathway is often associated with Lewy body dementia, a disease in the same family as Parkinson's, which is characterized by early constipation and sleep disturbance, followed by more symmetric slowing in movements and earlier dementia, as the disease spreads through both brain hemispheres.

New models to understand and study brain diseases

"These environmental toxicants are widespread and not everyone has Parkinson's disease," said Dorsey. "The timing, dose, and duration of exposure and interactions with genetic and other environmental factors are probably key to determining who ultimately develops Parkinson's. In most instances, these exposures likely occurred years or decades before symptoms develop."

Pointing to a growing body of research linking environmental exposure to Parkinson's disease, the authors believe the new models may enable the scientific community to connect specific exposures to specific forms of the disease. This effort will be aided by increasing public awareness of the adverse health effects of many chemicals in our environment. The authors conclude that their hypothesis "may explain many of the mysteries of Parkinson's disease and open the door toward the ultimate goal-prevention."

In addition to Parkinson's, these models of environmental exposure may advance understanding of how toxicants contribute to other brain disorders, including autism in children, ALS in adults, and Alzheimer's in seniors. Dorsey and his colleagues at the University of Rochester have organized a symposium on the Brain and the Environment in Washington, DC, on May 20 that will examine the role toxicants in our food, water, and air are playing in all these brain diseases.

Read more at Science Daily

Source rocks of the first real continents

Geoscientists have uncovered a missing link in the enigmatic story of how the continents developed -- a revised origin story that doesn't require the start of plate tectonics or any external factor to explain their formation. Instead, the findings published last week in Nature Communications, rely solely on internal geological forces that occurred within oceanic plateaus that formed during the first few hundred million years of Earth's history.

A major hurdle in understanding how the continents formed during the Archean Eon (four to 2.5 billion years ago) has been identifying the building blocks of Earth's early crust.

Much of the "new" Archean crust formed during this period comprised a very distinct association of three types of granitoid rocks -- tonalite, trondhjemite and granodiorite (TTG).

Understanding what went into making TTGs and the magmas they formed from has been difficult, because so many geological processes occurred between their initial melting and ultimate crystallization.

Earlier researchers focused on the trace element composition of these rocks, hoping to find clues about TTG magmas and their source.

"We tracked a specific set of trace elements that aren't affected by alteration and pristinely preserve signatures from the original magma that made new TTG crust," said Dr. Matthijs Smit, associate professor and Canada Research Chair at the University of British Columbia's (UBC) Department of Earth, Ocean and Atmospheric Sciences.

"These elements allowed us to look back through the chemical changes that TTG magmas go through and trace the melt compositions back to their initial state and source -- most likely a sort of gabbro."

"Funnily enough, many people have varieties of this type of rock as a kitchen countertop," Dr. Smit says.

"In a way, many people are preparing their dinner on the type of rock that was responsible for making our modern continents."

The Archean TTG crust is still part of the continents today.

For instance, in North America they make up much of the Canadian Interior between the Cordillera mountain belt in the west and the Grenville and Appalachian mountain belts in the east.

The majority of Ontario, Quebec, Manitoba, Saskatchewan, Northwest Territories and Nunavut is made up of Archean crustal fragments that are dominated by TTGs and their slightly younger and more evolved granite counterparts.

"All of these rocks -- and especially their combination -- can be explained by the model we present," said Dr. Smit.

"Ours is a simple model in which TTGs, as well as the younger rocks that TTGs are typically associated with, resulted from the slow burial, thickening and melting of precursor crust that likely resembled oceanic plateaus. The continental crust was destined to develop the way it did, because it kept getting buried further and the rocks at its base had no choice but to melt. In doing so, they made the TTGs that proved a winning recipe for continental survival and growth."

The UBC researchers' discovery of a stand-alone "intra-crustal" mechanism to make TTGs dispels the long-standing theory that Archean TTGs are formed in Earth's first subduction zones and mark the start of plate tectonics.

"There's always been a 'chicken-and-egg' question of which came first -- the start of plate tectonics or TTG magmatism to make new continental crust," says Dr. Smit.

"We show that these things may actually not be directly related. The recognition of the type of source rock makes this leap possible and also takes away the need to have other mechanisms, such as meteorite impact, explain the growth of the first real continents."

Read more at Science Daily

Study uncovers potential origins of life in ancient hot springs

Newcastle University research turns to ancient hot springs to explore the origins of life on Earth.

The research team, funded by the UK's Natural Environmental Research Council, investigated how the emergence of the first living systems from inert geological materials happened on the Earth, more than 3.5 billion years ago.

Scientists at Newcastle University found that by mixing hydrogen, bicarbonate, and iron-rich magnetite under conditions mimicking relatively mild hydrothermal vent results in the formation of a spectrum of organic molecules, most notably including fatty acids stretching up to 18 carbon atoms in length.

Published in the journal Communications Earth & Environment, their findings potentially reveal how some key molecules needed to produce life are made from inorganic chemicals, which is essential to understanding a key step in how life formed on the Earth billions of years ago.

Their results may provide a plausible genesis of the organic molecules that form ancient cell membranes, that were perhaps selectively chosen by early biochemical processes on primordial Earth.

Fatty acids in the early stages of life

Fatty acids are long organic molecules that have regions that both attract and repel water that will automatically form cell-like compartments in water naturally and it is these types of molecules that could have made the first cell membranes.

Yet, despite their importance, it was uncertain where these fatty acids came from in the early stages of life.

One idea is that they might have formed in the hydrothermal vents where hot water, mixed with hydrogen-rich fluids coming from underwater vents mixed with seawater containing CO2.

The group replicated crucial aspects of the chemical environment found in early Earth's oceans and the mixing of the hot alkaline water from around certain types of hydrothermal vents in their laboratory.

They found that when hot hydrogen-rich fluids were mixed with carbon dioxide-rich water in the presence of iron-based minerals that were present on the early Earth it created the types of molecules needed to form primitive cell membranes.

Lead author, Dr Graham Purvis, conducted the study at Newcastle University and is currently a Postdoctoral Research Associate at Durham University.

He said: "Central to life's inception are cellular compartments, crucial for isolating internal chemistry from the external environment. These compartments were instrumental in fostering life-sustaining reactions by concentrating chemicals and facilitating energy production, potentially serving as the cornerstone of life's earliest moments.

The results suggest that the convergence of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the rudimentary membranes of early cells at the very beginning of life.

This process might have engendered a diversity of membrane types, some potentially serving as life's cradle when life first started.

Principal Investigator Dr Jon Telling, Reader in Biogeochemistry, at School of Natural Environmental Sciences, added:

"We think that this research may provide the first step in how life originated on our planet. Research in our laboratory now continues on determining the second key step; how these organic molecules which are initially 'stuck' to the mineral surfaces can lift off to form spherical membrane-bounded cell-like compartments; the first potential 'protocells' that went on to form the first cellular life."

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Magnetic fields in the cosmos: Dark matter could help us discover their origin

The mini-halos of dark matter scattered throughout the Cosmos could function as highly sensitive probes of primordial magnetic fields. This is what emerges from a theoretical study conducted by SISSA and published in Physical Review Letters. Present on immense scales, magnetic fields are found everywhere in the Universe. However, their origin are still subjects of debate among scholars. An intriguing possibility is that magnetic fields originated near the birth of the universe itself, that is they are primordial magnetic fields.

In the study, researchers showed that if magnetic fields are indeed primordial then it could cause an increase in dark matter density perturbations on small scales.

The ultimate effect of this process would be the formation of mini-halos of dark matter, which, if detected would hint towards a primordial nature of magnetic fields.

Thus, in an apparent paradox, the invisible part of our Universe could be useful in resolving the nature of a component of the visible one.

Shedding light on the formation of Magnetic Fields

"Magnetic fields are ubiquitous in the Cosmos," explains Pranjal Ralegankar of SISSA, the author of the research.

"A possible theory regarding their formation suggests that those observed so far could be produced in the early stages of our Universe. However, this proposition lacks explanation in the standard model of physics. To shed light on this aspect and find a way to detect "primordial" magnetic fields, with this work we propose a method that we could define as 'indirect.' Our approach is based on a question: What is the influence of magnetic fields on dark matter?" It is known that there is no direct interaction.

Still, as Ralegankar explains, "there is an indirect one that occurs through gravity."

Right from the primordial Universe

Primordial magnetic fields can enhance density perturbations of electrons and protons in the primordial Universe.

When these become too large, they influence the magnetic fields themselves.

The consequence is the suppression of fluctuations on a small scale.

Ralegankar explains: "In the study, we show something unexpected. The growth in baryon density gravitationally induces the growth of dark matter perturbations without the possibility of subsequent cancellation. This would result in their collapse on small scales, producing mini-halos of dark matter." The consequence, continues the author, is that although fluctuations in the density of baryonic matter are cancelled, they would leave traces through the mini-halos, all solely through gravitational interactions.

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Astronomers detect seismic ripples in ancient galactic disk

A new snapshot of an ancient, far-off galaxy could help scientists understand how it formed and the origins of our own Milky Way.

At more than 12 billion years old, BRI 1335-0417 is the oldest and furthest known spiral galaxy in our universe.

Lead author Dr Takafumi Tsukui said a state-of-the-art telescope called ALMA allowed them to look at this ancient galaxy in much greater detail.

"Specifically, we were interested in how gas was moving into and throughout the galaxy," Dr Tsukui said.

"Gas is a key ingredient for forming stars and can give us important clues about how a galaxy is actually fuelling its star formation."

In this case, the researchers were able to not only capture the motion of the gas around BRI 1335-0417, but also reveal a seismic wave forming -- a first in this type of early galaxy.

The galaxy's disk, a flattened mass of rotating stars, gas and dust, moves in a way not dissimilar to ripples spreading on a pond after a stone is thrown in.

"The vertically oscillating motion of the disk is due to an external source, either from new gas streaming into the galaxy or by coming into contact with other smaller galaxies," Dr Tsukui said.

"Both possibilities would bombard the galaxy with new fuel for star formation.

"Additionally, our study revealed a bar-like structure in the disk. Galactic bars can disrupt gas and transport it towards the galaxy's centre. The bar discovered in BRI 1335-0417 is the most distant known structure of this kind.

"Together, these results show the dynamic growth of a young galaxy."

Because BRI 1335-0417 is so far away, its light takes longer to reach Earth.

The images seen through a telescope in the present day are a throwback to the galaxy's early days -- when the Universe was just 10 per cent of its current age.

"Early galaxies have been found to form stars at a much faster rate than modern galaxies. This is true for BRI 1335-0417, which, despite having a similar mass to our Milky Way, forms stars at rate a few hundred times faster," co-author Associate Professor Emily Wisnioski said.

"We wanted to understand how gas is supplied to keep up with this rapid rate of star formation.

"Spiral structures are rare in the early Universe, and exactly how they form also remains unknown. This study also gives us crucial information on the most likely scenarios.

Read more at Science Daily

Common origin behind major childhood allergies

Several major childhood allergies may all stem from the community of bacteria living in our gut, according to a new study led by researchers at the University of British Columbia and BC Children's Hospital.

The research, published in Nature Communications, identifies gut microbiome features and early life influences that are associated with children developing any of four common allergies -- eczema, asthma, food allergy and/or hay fever. The findings could lead to methods of predicting whether a child will develop allergies, and ways to prevent them from developing at all.

"We're seeing more and more children and families seeking help at the emergency department due to allergies," said Dr. Stuart Turvey, professor in the department of pediatrics at UBC and an investigator at BC Children's Hospital Research Institute, and co-senior author on the study. "Hundreds of millions of children worldwide suffer from allergies, including one in three children in Canada, and it's important to understand why this is happening and how it can be prevented."

The study is one of the first to examine four distinct school-aged pediatric allergies at once. While these allergic diseases each have unique symptoms, the Turvey lab was curious whether they might have a common origin linked to the infant gut microbiota composition.

"These are technically different diagnoses, each with their own list of symptoms, so most researchers tend to study them individually," says Dr. Charisse Petersen, co-senior author on the paper and postdoctoral fellow in the Turvey lab. "But when you look at what is going wrong at a cellular level, they actually have a lot in common."

For the study, researchers examined clinical assessments from 1,115 children who were tracked from birth to age five. Roughly half of the children (523) had no evidence of allergies at any time, while more than half (592) were diagnosed with one or more allergic disorders by an expert physician. The researchers evaluated the children's microbiomes from stool samples collected at clinical visits at three months and one year of age.

The stool samples revealed a bacterial signature that was associated with the children developing any of the four allergies by five years of age. The bacterial signature is a hallmark of dysbiosis, or an imbalanced gut microbiota, that likely resulted in a compromised intestinal lining and an elevated inflammatory response within the gut.

"Typically, our bodies tolerate the millions of bacteria living in our guts because they do so many good things for our health. Some of the ways we tolerate them are by keeping a strong barrier between them and our immune cells and by limiting inflammatory signals that would call those immune cells into action," says Courtney Hoskinson, a PhD candidate at UBC and first author on the paper. "We found a common breakdown in these mechanisms in babies prior to the development of allergies."

Many factors can shape the infant gut microbiota, including diet, how we are born, where we live, and our exposure to antibiotics. For example, antibiotics may wipe out sensitive bacteria, while breastfeeding tends to replenish and provide necessary food for bacteria in the infant gut. The researchers examined how these types of influences affected the balance of gut microbiota and the development of allergies.

"There are a lot of potential insights from this robust analysis," says Dr. Turvey. "From these data we can see that factors such as antibiotic usage in the first year of life are more likely to result in later allergic disorders, while breastfeeding for the first six months is protective. This was universal to all the allergic disorders we studied."

Now the researchers hope to leverage the findings to inform treatments that correct an imbalanced gut microbiota and could potentially prevent allergies from developing.

"Developing therapies that change these interactions during infancy may therefore prevent the development of all sorts of allergic diseases in childhood, which often last a lifetime," says Dr. Turvey.

The research is part of the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study that recruited families through BC Children's Hospital and BC Women's Hospital + Health Centre and other pediatric hospitals across Canada. Since launching in 2008, the team of Canadian researchers has tracked the health, growth and environments of kids from birth and made important discoveries about how asthma and allergies develop.

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New type of star gives clues to mysterious origin of magnetars

Magnetars are the strongest magnets in the Universe. These super-dense dead stars with ultra-strong magnetic fields can be found all over our galaxy but astronomers don't know exactly how they form. Now, using multiple telescopes around the world, including European Southern Observatory (ESO) facilities, researchers have uncovered a living star that is likely to become a magnetar. This finding marks the discovery of a new type of astronomical object -- massive magnetic helium stars -- and sheds light on the origin of magnetars.

Despite having been observed for over 100 years, the enigmatic nature of the star HD 45166 could not be easily explained by conventional models, and little was known about it beyond the fact that it is one of a pair of stars, is rich in helium and is a few times more massive than our Sun.

"This star became a bit of an obsession of mine," says Tomer Shenar, the lead author of a study on this object published today in Science and an astronomer at the University of Amsterdam, the Netherlands. "Tomer and I refer to HD 45166 as the 'zombie star'," says co-author and ESO astronomer Julia Bodensteiner, based in Germany. "This is not only because this star is so unique, but also because I jokingly said that it turns Tomer into a zombie."

Having studied similar helium-rich stars before, Shenar thought magnetic fields could crack the case. Indeed, magnetic fields are known to influence the behaviour of stars and could explain why traditional models failed to describe HD 45166, which is located about 3000 light-years away in the constellation Monoceros. "I remember having a Eureka moment while reading the literature: 'What if the star is magnetic?'," says Shenar, who is currently based at the Centre for Astrobiology in Madrid, Spain.

Shenar and his team set out to study the star using multiple facilities around the globe. The main observations were conducted in February 2022 using an instrument on the Canada-France-Hawaii Telescope that can detect and measure magnetic fields. The team also relied on key archive data taken with the Fiber-fed Extended Range Optical Spectrograph (FEROS) at ESO's La Silla Observatory in Chile.

Once the observations were in, Shenar asked co-author Gregg Wade, an expert on magnetic fields in stars at the Royal Military College of Canada, to examine the data. Wade's response confirmed Shenar's hunch: "Well my friend, whatever this thing is -- it is definitely magnetic."

Shenar's team had found that the star has an incredibly strong magnetic field, of 43,000 gauss, making HD 45166 the most magnetic massive star found to date. "The entire surface of the helium star has a magnetic field almost 100,000 times stronger than Earth's," explains co-author Pablo Marchant, an astronomer at KU Leuven's Institute of Astronomy in BelgiumThis observation marks the discovery of the very first massive magnetic helium star. "It is exciting to uncover a new type of astronomical object," says Shenar, "especially when it's been hiding in plain sight all along."

Moreover, it provides clues to the origin of magnetars, compact dead stars laced with magnetic fields at least a billion times stronger than the one in HD 45166. The team's calculations suggest that this star will end its life as a magnetar. As it collapses under its own gravity, its magnetic field will strengthen, and the star will eventually become a very compact core with a magnetic field of around 100 trillion gauss -- the most powerful type of magnet in the Universe.

Read more at Science Daily

Detailed map of the heart provides new insights into cardiac health and disease

In a new study, published today (12 July) in Nature, researchers have produced the most detailed and comprehensive human Heart Cell Atlas to date, including the specialised tissue of the cardiac conduction system -- where the heartbeat originates.

The multi-centre team is led by the Wellcome Sanger Institute and the National Heart and Lung Institute at Imperial College London, and has also presented a new drug-repurposing computational tool called Drug2cell, which can provide insights into the effects of drugs on heart rate.

This study is part of the international Human Cell Atlas* (HCA) initiative, which is mapping every cell type in the human body, to transform our understanding of health and disease, and will form the foundation for a fully integrated HCA Human Heart Cell Atlas.

Charting eight regions of the human heart, the work describes 75 different cell states including the cells of the cardiac conduction system -- the group of cells responsible for the heartbeat -- not understood at such a detailed level in humans before. The human cardiac conduction system, the heart's 'wiring', sends electrical impulses from the top to the bottom of the heart and coordinates the heartbeat.

By using spatial transcriptomics, which gives a "map" of where cells sit within a tissue, researchers were also able to understand how these cells communicate with each other for the first time. This map acts as a molecular guidebook, showing what healthy cells look like, and providing a crucial reference to understand what goes wrong in disease. The findings will help understand diseases such as those affecting the heart rhythm.

The assembly of a Human Heart Cell Atlas is key given that cardiovascular diseases are the leading cause of death globally. Around 20,000 electronic pacemakers are implanted each year in the UK for these disorders. These can be ineffective and are prone to complications and side-effects. Understanding the biology of the cells of the conduction system and how they differ from muscle cells paves the way to therapies to boost cardiac health and develop targeted treatments for arrhythmias.

The team also presents a new computational tool called Drug2cell. The tool can predict drug targets as well as drug side effects. It leverages single-cell profiles and the 19 million drug-target interactions in the EMBL-EBI ChEMBL database.

Unexpectedly, this tool identified that pacemaker cells express the target of certain medications, such as GLP1 drugs, which are used for diabetes and weight loss and are known to increase the heart rate as a side-effect, the mechanism of which was unclear. This study suggests that the increase in heart rate might be partly due to a direct action of these drugs on pacemaker cells, a finding the team also showed in an experimental stem cell model of pacemaker cells.

Dr James Cranley, joint first author, a cardiologist specialising in heart rhythm disorders and PhD student at the Wellcome Sanger Institute, said: "The cardiac conduction system is critical for the regular and coordinated beating of our hearts, yet the cells which make it up are poorly understood. This study sheds new light by defining the profiles of these cells, as well as the multicellular niches they inhabit. This deeper understanding opens the door to better, targeted anti-arrhythmic therapies in the future."

Dr Kazumasa Kanemaru, joint first author and Postdoctoral Fellow in the Gene Expression Genomics team at the Wellcome Sanger Institute, said: "The mechanism of activating and suppressing pacemaker cell genes is not clear, especially in humans. This is important for improving cell therapy to facilitate the production of pacemaker cells or to prevent the excessive spontaneous firing of cells. By understanding these cells at an individual genetic level, we can potentially develop new ways to improve heart treatments."

The study unearthed an unexpected discovery: a close relationship between conduction system cells and glial cells. Glial cells are part of the nervous system and are traditionally found in the brain. They have been explored very little in the heart. This research suggests that glial cells are in physical contact with conduction system cells and may play an important supporting role: communicating with the pacemaker cells, guiding nerve endings to them, and supporting their release of glutamate, a neurotransmitter.

Another key finding of the study is an immune structure on the heart's outer surface. This contains plasma cells, which release antibodies into the space around the heart to prevent infection from the nearby lungs. The researchers also identified a cellular niche enriching for a hormone that could be interpreted as an early warning sign of heart failure.

Dr Michela Noseda, senior Lecturer in Cardiac Molecular Pathology at the National Heart and Lung Institute, Imperial College London, a Coordinator of the Human Cell Atlas Heart BioNetwork and a lead author, said: "We often don't fully know what impact a new treatment will have on the heart and its electrical impulses -- this can mean a drug is withdrawn or fails to make it to the market. Our team developed the Drug2cell platform to improve how we evaluate new treatments and how they can affect our hearts, and potentially other tissues too. This could provide us with an invaluable tool to identify new drugs which target specific cells, as well as help to predict any potential side-effects early on in drug development."

Professor Metin Avkiran, Associate Medical Director at the British Heart Foundation, which part-funded the research with the German Centre for Cardiovascular Research (DZHK), said: "Using cutting-edge technologies, this research provides further intricate detail about the cells that make up specialised regions of the human heart and how those cells communicate with each other. The new findings on the heart's electrical conduction system and its regulation are likely to open up new approaches to preventing and treating rhythm disturbances that can impair the heart's function and may even become life-threatening."

"International collaboration is key to scientific progress. This impactful study and other discoveries from the broader Human Cell Atlas initiative are excellent examples of what can be achieved when the international research community works together across borders. Our combined efforts can ultimately produce better outcomes for patients worldwide."

Read more at Science Daily

Discovery of 500-million-year-old fossil reveals astonishing secrets of tunicate origins

Karma Nanglu says his favorite animal is whichever one he's working on. But his latest subject may hold first place status for a while: a 500-million-year-old fossilfrom the wonderfully weird group of marine invertebrates, the tunicates.

"This animal is as exciting a discovery as some of the stuff I found when hanging off a cliffside of a mountain, or jumping out of a helicopter. It's just as cool," said Nanglu, postdoctoral researcher in the Department of Organismic and Evolutionary Biology at Harvard University.

In a new study in Nature Communications, Nanglu and coauthors describe the new fossil, named Megasiphon thylakos, revealing that ancestral tunicates lived as stationary, filter-feeding adults and likely underwent metamorphosis from a tadpole-like larva.

Tunicates are truly strange creatures that come in all shapes and sizes with a wide variety of lifestyles. An adult tunicate's basic shape is typically barrel-like with two siphons projecting from its body. One of the siphons draws in water with food particles through suction, allowing the animal to feed using an internal basket-like filter device. After the animal feeds, the other siphon expels the water.

There are two main tunicate lineages, ascidiaceans (often called "sea squirts") and appendicularias. Most ascidiaceans begin their lives looking like a tadpole and mobile, then metamorph into a barrel shaped adult with two siphons. They live their adult life attached to the seafloor. In contrast, appendicularians retain the look of a tadpole as they grow to adults and swim freely in the upper waters.

"This idea that they begin as tadpole-looking larva that, when ready to develop, basically headbutts a rock, sticks to it, and begins to metamorphosis by reabsorbing its own tail to transform into this being with two siphons is just awe-inspiring," sais Nanglu.

Interestingly, tunicates are the closest relatives of vertebrates, which includes fish, mammals, and even humans. How this odd-looking creature could be related to vertebrates is hard to imagine were it not for that tadpole beginning. Tunicate's close relationship to vertebrates makes studying them critical for understanding our own evolutionary origins. Unfortunately, it's not easy to do as tunicates are almost completely absent from the entire fossil record, with only a handful of fossils appearing convincingly as members of the group.

With so few fossils, scientists relied mainly on what could be learned from modern tunicate species. Because no one knew the morphology and ecology of the last common ancestor of the tunicates, scientists could only hypothesize that it was either a benthic animal with two siphons, like the ascidiaceans, or a free-swimming animal like the appendicularians.

M. thylakos had all the basic hallmarks of an ascidiacean tunicate, a barrel-shaped body and two prominent siphon-like growths. But the feature that stood out to the team was the dark bands running up and down the fossil's body.

High powered images of M. thylakos allowed the researchers to conduct a side-by-side comparison to a modern ascidiacean. The researchers used dissected sections of the modern tunicate Ciona to identify the nature of Megasiphon's dark bands. The comparisons revealed remarkable similarities between Ciona's muscles, which allow the tunicate to open and close its siphons, and the dark bands observed in the 500-million-year-old fossil.

"Megasiphon's morphology suggests to us that the ancestral lifestyle of tunicates involved a non-moving adult that filter fed with its large siphons," said Nanglu. "It's so rare to find not just a tunicate fossil, but one that provides a unique and unparalleled view into the early evolutionary origins of this enigmatic group."

M. thylakos is the only definitive tunicate fossil with soft tissue preservation that has been discovered to date. It is the oldest of its kind originating from the middle Cambrian Marjum Formation in Utah. The fossil was recognized as a tunicate by co-authors research associate, Rudy Lerosey-Aubril, and Professor Javier Ortega-Hernández (both in the Department of Organismic and Evolutionary Biology) while visiting the Utah Museum of Natural History (UMNH) in 2019.

"The fossil immediately caught our attention," said Ortega-Hernández, "although we mostly work on Cambrian arthropods, such as trilobites and their soft bodied relatives, the close morphological similarity of Megasiphon with modern tunicates was simply too striking to overlook, and we immediately knew that the fossil would have an interesting story to tell."

Fossils from the Marjum Formation date from shortly after the Cambrian Explosion, one of the most significant evolutionary events in Earth's history which occurred approximately 538 million years ago. During this time the most major animal groups appeared in the fossil record for the first time radically changing marine ecosystems. Tunicates, however, are noticeably absent in Cambrian rocks even though they are diverse and abundant in modern oceans.

There are many Cambrian fossil sites with exceptional preservation in the United States, but these are often overlooked compared to those from the Burgess Shale in Canada and Chengjiang in China. "The discovery of Megasiphon perfectly illustrates why Javier and I have been conducting fieldwork in Utah for the last ten years," said Lerosey-Aubril. "The Marjum strata has all of our attention right now as we know that it preserves fossils of animal groups, such as tunicates or comb jellies, that are almost entirely absent from the Cambrian fossil record."

Molecular clock estimates suggest that ascidiaceans originated 450 million years ago. However, at 500 million years old, M. thylakos provides the clearest view into the anatomy of ancient tunicates and their earliest evolutionary history. Significantly, M. thylakos provides evidence that most of the modern body plan of tunicates was already established soon after the Cambrian Explosion.

"Given the exceptional quality of preservation and the age of the fossil, we can actually say quite a bit about the evolutionary history of the tunicates," said Nanglu. "This is an incredible find as we had virtually no conclusive evidence for the ancestral modes of life for this group before this."

After collecting hundreds of new fossils again this spring, the researchers are convinced the Marjum Formation has only started to reveal its secrets.

Read more at Science Daily

Where do our limbs come from?

An international collaboration that includes scientists from the University of Colorado School of Medicine has uncovered new clues about the origin of paired appendages -- a major evolutionary step that remains unresolved and highly debated.

The researchers describe their study in an article published today in the journal Nature.

"This has become a topic that comes with bit of controversy, but it's really a very fundamental question in evolutionary biology: Where do our limbs come from?" says co-corresponding author Christian Mosimann, PhD, associate professor and Johnson Chair in the Department of Pediatrics, Section of Developmental Biology at CU School of Medicine.

That question -- where do our limbs come from? -- has been subject of debate for more than 100 years. In 1878, German scientist Carl Gegenbaur proposed that paired fins derived from a source called the gill arch, which are bony loops present in fish to support their gills. Other scientists favor the lateral fin fold hypothesis, concluding that lateral fins on the top and bottom of the fish are the source of paired fins.

"It is a highly active research topic because it's been an intellectual challenge for such a long time," Mosimann says. "Many big labs have studied the various aspects of how our limbs develop and have evolved." Among those labs are Dr. Mosimann's colleagues and co-authors, Tom Carney, PhD, and his team at the Lee Kong Chian School of Medicine at Nanyang Technological University in Singapore.

Chasing the odd cells

For Mosimann, the inquiry into where limbs come from is an offshoot of other research conducted by his laboratory on the CU Anschutz Medical Campus. In his laboratory, his team uses zebrafish as a model to understand the development from cells to organs. He and his team study how cells decide their fate, looking for explanations for how development can go awry leading to congenital anomalies, in particular cardiovascular and connective tissue diseases.

Along the way, Mosimann and his lab team observed how a peculiar cell type with features of connective tissue cells, so-called fibroblasts that share a developmental origin with the cardiovascular system, migrated into specific developing fins of the zebrafish. It turns out that these cells may support a connection between the competing theories of paired appendage evolution.

"We always knew these cells were odd," he says. "There were these fibroblast-looking cells that went into the so-called ventral fin, the fin at the belly of the developing zebrafish. Similar fibroblast cells didn't crawl into any other fin except the pectoral fin, which are the equivalent of our arms. So we kept noticing these peculiar fibroblasts, and we could never make sense of what these were for many years."

The Mosimann lab has developed several techniques to track cell fates during development in pursuit of their main topic, which is an improved understanding of how the embryonic cell layer, called the lateral plate mesoderm, contributes to diverse organs. The lateral plate mesoderm is the developmental origin of the heart, blood vessels, kidneys, connective tissue, as well as major parts of limbs.

The paired fins that form the equivalent of our arms and legs are seeded by cells from the lateral plate mesoderm, while other fins are not. Understanding how these particular fins became more limb-like has been at the core of a long-standing debate.

Developing new theories

Hannah Moran, who is pursuing her PhD in the Cell Biology, Stem Cells and Development program in the Mosimann lab, adapted a method of tracking lateral plate mesoderm cells that contribute to heart development so that researchers could track the peculiar fibroblasts related to limb development.

"My primary research project focuses on the development of the heart rather than limb development," Moran says, "but there was a genetic technique that I had adapted to map early heart cells, and so we were able to implement that into mapping where the mysterious cells of the ventral fin came from. And turns out, they are also from the lateral plate mesoderm."

This crucial discovery provides a new puzzle piece to the big picture of how we evolved our arms and legs. Increasing evidence supports a hypothesis of paired appendage evolution called the dual origin theory.

"Our data fit nicely into this combined theory, but it can also stand on its own with the lateral fin theory," says Robert Lalonde, PhD, postdoctoral fellow in the Mosimann lab. "While paired appendages arise from the lateral plate mesoderm, that does not rule out an ancient connection to unpaired, lateral fins."

By observing the mechanisms of embryonic development and comparing the anatomy of existing species, research groups like Mosimann's can develop theories on how embryonic structures may have evolved or have been modified over time.

"The embryo has features that are still ancient remnants that they have not lost yet, which provides insight into how animals have evolved," Mosimann says. "We can use the embryo to learn more about features that just persist today, allowing us to kind of travel back in time," Mosimann says. "We see that the body has a fundamental, inherent propensity to form bilateral, two-sided structures. Our study provides a molecular and genetic puzzle piece to resolve how we came to have limbs. It adds to this 100-plus year discussion, but now we have molecular insights."

International collaboration

Collaborations with colleagues in laboratories across the country and around the world are another important part of the study. Those scientists bring additional specializations and contribute data from other models, including paddlefish, African clawed frogs, and a variant of split-tail goldfish called Ranchu, to study embryonic development.

"There are labs on this on this paper that work on musculoskeletal diseases, toxicology, fibrosis. We work on cardiovascular, congenital anomalies, cardiopulmonary anomalies, limb development, all related to our interest on the lateral plate mesoderm," says Mosimann. "And then together, you get to make such fundamental discoveries. And that's where team science enables us to do something that is more than just the sum of the parts."

For all the considerable work and significance of the study, the Mosimann team recognizes that it is a key step, but not the end of the journey in the debate about paired appendages.

Read more at Science Daily

Helium nuclei research advances our understanding of cosmic ray origin and propagation

The CALorimetric Electron Telescope (CALET), aboard the Kibo's Exposed Facility (EF) of the International Space Station, has been on a mission to measure the flux of cosmic ray particles since 2015. In a new study, an international team of researchers report the results of a direct measurement of the cosmic ray helium spectrum using the data collected by CALET. In contrast to the single power-law that was previously believed to exist, analysis of the flux data collected between 2015 and 2022 reveals that the energy distribution of cosmic ray helium nuclei follows a Double Broken Power Law.

Much of our understanding of the Universe and its mysterious phenomena is based on theoretical interpretations. In order to deepen the understanding of distant objects and energetic phenomena, astronomers are looking at cosmic rays, which are high-energy charged particles composed of protons, electrons, atomic nuclei, and other subatomic particles. Such studies have revealed that cosmic rays contain all the elements known to us in the periodic table, suggesting that these elements originate from stars and high-energy events such as supernovae. Additionally, due to their charged nature, the path of cosmic rays through space is influenced by the magnetic fields of interstellar phenomena and objects.

Detailed observations of cosmic rays can, thus, not only shed light on the origins of these particles but also decode the existence of high-energy objects and phenomena such as supernova remnants, pulsars, and even dark matter. In an effort to better observe high-energy radiations, Japan, Italy, and USA collaboratively established the CALorimetric Electron Telescope (CALET) on the International Space Station in 2015.

In 2018, observations of the cosmic ray proton spectrum from 50 GeV to 10 TeV revealed that the particle flux of protons at high energies was significantly higher than expected. These results deviated from the conventional cosmic ray acceleration and propagation models that assume a "single power-law distribution," wherein the number of particles decrease with increasing energy.

Consequently, in a study published in 2022, the CALET team, including researchers from Waseda University, found cosmic ray protons in the energy range of 50 GeV to 60 TeV to follow a "Double Broken Power Law." This law assumes that the number of high-energy particles initially increase until 10 TeV (known as spectral hardening) and then decrease with an increase in energy (known as spectral softening).

Extending these observations further, the team has now found similar trends of spectral hardening and softening in the cosmic ray helium spectrum captured over a broad range of energy, from 40 GeV to 250 TeV.

The study, published in the journal Physical Review Letters on 27 April, 2023, was led by Associate Professor Kazuyoshi Kobayashi from Waseda University, Japan, along with contributions from Professor Emeritus Shoji Torii, Principal Investigator of the CALET project, also affiliated with Waseda University, and Research Assistant Paolo Brogi from the University of Siena in Italy.

"CALET has successfully observed energy spectral structure of cosmic ray helium, especially spectral hardening starting from around 1.3 TeV, and the tendency of softening starting from around 30 TeV," says Kobayashi.

These observations are based on data collected by CALET aboard the International Space Station (ISS) between 2015 to 2022. Representing the largest energy range to date for cosmic helium nuclei particles, these observations provide additional evidence for deviation of the particle flux from the single power-law model. The researchers noticed that deviation from the expected power-law distribution was more than eight standard deviations away from the mean, indicating a very low probability of this deviation occurring by chance.

Notably, the initial spectral hardening observed in this data suggests that there may be unique sources or mechanisms that are responsible for accelerating and propagating the helium nuclei to high energies. The discovery of these spectral features is also supported by recent observations from the Dark Matter Particle Explorer, and questions our current understanding of the origin and nature of cosmic rays.

"These results would significantly contribute to the understanding of cosmic ray acceleration in the supernova remnant and propagation mechanism," says Torii.

Read more at Science Daily

A journey to the origins of multicellular life: Long-term experimental evolution in the lab

The world would look very different without multicellular organisms -- take away the plants, animals, fungi, and seaweed, and Earth starts to look like a wetter, greener version of Mars. But precisely how multicellular organisms evolved from single-celled ancestors remains poorly understood. The transition happened hundreds of millions of years ago, and early multicellular species are largely lost to extinction.

To investigate how multicellular life evolves from scratch, researchers from the Georgia Institute of Technology decided to take evolution into their own hands. Led by William Ratcliff, associate professor in the School of Biological Sciences and director of the Interdisciplinary Graduate Program in Quantitative Biosciences, a team of researchers has initiated the first long-term evolution experiment aimed at evolving new kinds of multicellular organisms from single-celled ancestors in the lab.

Over 3,000 generations of laboratory evolution, the researchers watched as their model organism, "snowflake yeast," began to adapt as multicellular individuals. In research published in Nature, the team shows how snowflake yeast evolved to be physically stronger and more than 20,000 times larger than their ancestor. This type of biophysical evolution is a pre-requisite for the kind of large multicellular life that can be seen with the naked eye. Their study is the first major report on the ongoing Multicellularity Long-Term Evolution Experiment (MuLTEE), which the team hopes to run for decades.

"Conceptually, what we want to understand is how simple groups of cells evolve into organisms, with specialization, coordinated growth, emergent multicellular behaviors, and life cycles -- the stuff that differentiates a pile of pond scum from an organism that is capable of sustained evolution," Ratcliff said. "Understanding that process is a major goal of our field."

The Multicellularity Long-Term Evolution Experiment

Ozan Bozdag, a research scientist and former postdoctoral researcher in Ratcliff's group and first author on the paper, initiated the MuLTEE in 2018, starting with single-celled snowflake yeast. Bozdag grew the yeast in shaking incubators and each day selected for both faster growth and larger group size.

The team selected on organism size because all multicellular lineages started out small and simple, and many evolved to be larger and more robust over time. The ability to grow large, tough bodies is thought to play a role in increasing complexity, as it requires new biophysical innovations. However, this hypothesis had never been directly tested in the lab.

Over about 3,000 generations of evolution, their yeast evolved to form groups that were more than 20,000 times larger than their ancestor. They went from being invisible to the naked eye to the size of fruit flies, containing over half a million cells. The individual snowflake yeast evolved novel material properties: while they started off weaker than gelatin, they evolved to be as strong and tough as wood.

New Biophysical Adaptations

In investigating how the snowflake yeast adapted to become larger, the researchers observed that the yeast cells themselves became elongated, reducing the density of cells packed into the group. This cell elongation slowed down the accumulation of cell-to-cell stress that would normally cause the clusters to fracture, allowing the groups to get larger. But this fact alone should have only resulted in small increases in size and multicellular toughness.

To uncover the precise biophysical mechanisms that allowed growth to macroscopic size, the researchers needed to look inside the yeast clusters to see how the cells interacted physically. Normal light microscopes were unable to penetrate the large, densely packed groups, so the researchers used a scanning electron microscope to image thousands of ultrathin slices of the yeast, which gave them their internal structure.

"We discovered that there was a totally new physical mechanism that allowed the groups to grow to this very, very large size," Bozdag said. "The branches of the yeast had become entangled -- the cluster cells evolved vine-like behavior, wrapping around each other and strengthening the entire structure."

By simply selecting on organismal size, the researchers figured out how to leverage the biomechanical mechanism of entanglement, which ended up making the yeast about 10,000 times tougher as a material.

"Entanglement has previously been studied in totally different systems, mostly in polymers," said Peter Yunker, associate professor in the School of Physics and a co-author on the paper. "But here we're seeing entanglement through an entirely different mechanism -- the growth of cells rather than just through their movement."

Observing the entanglement was a turning point in the researchers' understanding of how simple multicellular groups evolve. As a brand-new multicellular organism, snowflake yeast lacks the sophisticated developmental mechanisms that characterize modern multicellular organisms. But after just 3,000 generations of laboratory evolution, the yeast figured out how to drive and co-opt cellular entanglement as a developmental mechanism.

Preliminary investigations of other multicellular fungi show that they also form highly entangled multicellular bodies, suggesting that entanglement is a widespread and important multicellular trait in this branch of multicellular life.

"I'm really excited to have a model system where we can evolve early multicellular life over thousands of generations, harnessing the awesome power of modern science," Ratcliff said. "In principle, we can understand everything that is happening, from the evolutionary cell biology to the biophysical traits which are directly under selection."

For a long time, humans have worked with biology to evolve new things -- from the corn we eat to domesticated dogs, chickens, and show pigeons. According to Ratcliff, what their team is doing is not so different.

Read more at Science Daily

Scientists present evidence for a billion-years arms race between viruses and their hosts

Researchers have proposed a new evolutionary model for the origin of a kingdom of viruses called Bamfordvirae, suggesting a billion-years evolutionary arms race between two groups within this kingdom and their hosts.

Their study, published today as a Reviewed Preprint in eLife, provides what the editors say are convincing analyses that advance our understanding of the deep evolutionary history of viruses, the interaction between viruses and the first eukaryotes (organisms with cells that include a nucleus), and the diversification of viral lineages.

Viruses in the kingdom Bamfordvirae make up one of the most diverse groups that infect living organisms. They include the Nucleocytoplasmic Large DNA viruses (NCLDVs; the largest viruses characterised to date), virophages (viral parasites of other viruses), adenoviruses (common viruses that cause cold and flu-like symptoms), and Mavericks and Polinton-like viruses (both virus-like mobile genetic elements that colonise the genomes of their hosts).

There are two main hypotheses for the origins of these viruses: the 'nuclear-escape' and 'virophage-first' hypotheses. The nuclear-escape hypothesis says that a Maverick-like ancestor originated with hosts (endogenous), escaped from the host cell nucleus and gave rise to adenoviruses and NCLDVs. In contrast, the virophage-first hypothesis suggests that NCLDVs co-evolved with early virophages. Mavericks then evolved from virophages that became endogenous, with adenoviruses escaping from the host nucleus at a later stage.

"Despite these proposed scenarios, the diversification of viruses in the Bamfordvirae kingdom remains a major open question in virus evolution. To gain a better understanding of their history, we wanted to test the predictions made by both the nuclear-escape and virophage-first models, and consider alternative scenarios regarding the origin of different lineages," says José Gabriel Niño Barreat, Postdoctoral Research Assistant at the University of Oxford, UK. Barreat is a co-author of the study alongside Aris Katzourakis, Professor of Evolution and Genomics at the University of Oxford's Department of Biology.

Barreat and Katzourakis used two hypothesis-testing methods (maximum-likelihood and Bayesian frameworks) to compare the plausibility of the nuclear-escape versus alternative evolutionary scenarios. They focused on four key proteins shared by viruses in this lineage which are involved in the formation of viral capsids: major and minor capsid proteins, DNA-packaging ATPase, and protease. They applied another two methods that use genetic data to estimate rooted phylogenies, to infer the evolutionary trajectory of the different lineages. Then, they assessed whether adenoviruses and NCLDVs descended from a common ancestor, as predicted by the nuclear-escape scenario.

Their analyses revealed strong evidence against a sister relationship between adenoviruses and NCLDVs, as suggested by the nuclear-escape hypothesis. Instead, the findings suggest that adenoviruses descended from a common ancestor with Mavericks, to the exclusion of NCLDVs. At odds with a virophage-first scenario, the researchers found that the most recent common ancestor of Mavericks and adenoviruses was not a virophage. However, their work does not rule out the virophage-first hypothesis completely, making it the one best supported by current phylogenetic analyses.

Additionally, their work provides support for the positioning of the Bamfordvirae ancestral root between virophages and the other viral lineages. This positioning pointed the team towards a new model for the evolutionary origins of these viruses.

"The model proposes that the Bamfordvirae ancestor did not originate from an invasion of the eukaryotic cell nucleus, and that it was a non-virophage DNA virus with a small genome," says co-author Aris Katzourakis. "The lifestyle of virophages would have evolved at a later stage as these became specialised parasites of the ancestral NCLDVs." Katzourakis adds that the relative timing of events suggests the most recent common ancestor of the Bamfordvirae kingdom existed more than a billion years ago, extending to the initial stages of eukaryotic life. However, an absolute timescale for the precise dating of these events is not currently available.

Another limitation of the study is that the phylogenetic signal in the protein data analysed may have been obscured by the deep divergences and extreme diversity in this lineage. However, the authors were able to robustly distinguish between alternative scenarios, and the focus on the origin and development of the viral capsid provides a simple way to explain the available data.

"This work contributes to our knowledge on how viruses evolve different evolutionary strategies, for example to become parasites of other viruses like virophages, or viral giants like NCLDVs," Barreat says. "As well as playing important roles in Earth's ecosystems, it is becoming increasingly clear that viruses may have contributed to major evolutionary transitions during the history of life. Therefore, understanding the deep evolutionary history of viruses provides more context for these ancient interactions and the actors involved."

Read more at Science Daily

Earth's first plants likely to have been branched

A new discovery by scientists at the University of Bristol changes ideas about the origin of branching in plants.

By studying the mechanisms responsible for branching, the team have determined what the first land plants are likely to have looked like millions of years ago.

Despite fundamentally different patterns in growth, their research has identified a common mechanism for branching in vascular plants.

Dr Jill Harrison from Bristol's School of Biological Sciences explained: "Diverse shapes abound in the dominant flowering plant group, and gardeners will be familiar with 'pinching out' plants' shoot tips to stimulate side branch growth, leading to a bushier overall form.

"However, unlike flowering plants, other vascular plants branch by splitting the shoot apex into two during growth, a process known as 'dichotomy'.

As an ancient vascular plant lineage that formed coal seams during the Carboniferous era, lycophytes preserve the ancestral pattern of dichotomous branching.

Using surgical experiments in a lycophyte, researchers at the University of Bristol have discovered that dichotomy is regulated by short range auxin transport and co-ordinated in different parts of the plant by long range auxin transport.

Published in Development, the findings that both flowering plant and lycophyte branching are regulated by auxin transport imply that similar mechanisms were present in the earliest vascular plants around 420 million years ago.

By combining these findings with discoveries made in the non-vascular, non-branching moss group we can infer what the first land plants looked like around 480 million years ago.

Previously, the Dr Harrison's lab disrupted auxin transport in a moss, leading it to branch in a similar manner to the earliest branching fossils.

Together these studies imply that the earliest land plants were branched, and that branching was lost during the evolution of non-vascular mosses.

Dr Jill Harrison explained: "The greening of the land by plants paved the way for all terrestrial life to evolve as it provided food for animals and oxygen to breathe, and branching was a key innovation in the radiation of land plants.

"Our work implies that branching evolved earlier than thought, which is an important evolutionary conclusion."

Read more at Science Daily

Surprising similarities in stone tools of early humans and monkeys

Researchers from the Max Planck Institute for Evolutionary Anthropology have discovered artefacts produced by old world monkeys in Thailand that resemble stone tools, which historically have been identified as intentionally made by early hominins. Until now, sharp-edged stone tools were thought to represent the onset of intentional stone tool production, one of the defining and unique characteristics of hominin evolution. This new study challenges long held beliefs about the origins of intentional tool production in our own lineage.

The research is based on new analyses of stone tools used by long-tailed macaques in the Phang Nga National Park in Thailand. These monkeys use stone tools to crack open hard-shelled nuts. In that process, the monkeys often break their hammerstones and anvils. The resulting assemblage of broken stones is substantial and widespread across the landscape. Moreover, many of these artefacts bear all of the same characteristics that are commonly used to identify intentionally made stone tools in some of the earliest archaeological sites in East Africa.

"The ability to intentionally make sharp stone flakes is seen as a crucial point in the evolution of hominins, and understanding how and when this occurred is a huge question that is typically investigated through the study of past artefacts and fossils. Our study shows that stone tool production is not unique to humans and our ancestors," says lead author Tomos Proffitt, a researcher at the Max Planck Institute for Evolutionary Anthropology. "The fact that these macaques use stone tools to process nuts is not surprising, as they also use tools to gain access to various shellfish as well. What is interesting is that, in doing so they accidently produce a substantial archaeological record of their own that is partly indistinguishable from some hominin artefacts."

New insights into the evolution of stone tool technology

By comparing the accidentally produced stone fragments made by the macaques with those from some of the earliest archaeological sites, the researchers were able to show that many of the artefacts produced by monkeys fall within the range of those commonly associated with early hominins. Co-lead author Jonathan Reeves highlights: "The fact that these artifacts can be produced through nut cracking has implications for the range of behaviours we associate with sharp edged flakes in the archaeological record.."

The newly discovered macaque stone tools offer new insights into how the first technology might have started in our earliest ancestors and that its origin may have been linked to similar nut cracking behaviour which could be substantially older than the current earliest archaeological record. "Cracking nuts using stone hammers and anvils, similar to what some primates do today, has been suggested by some as a possible precursor to intentional stone tool production. This study, along with previous ones published by our group, opens the door to being able to identify such an archaeological signature in the future," says Lydia Luncz, senior author of the study and head of the Technological Primates Research Group at the Max Planck Institute for Evolutionary Anthropology. "This discovery shows how living primates can help researchers investigate the origin and evolution of tool use in our own lineage."

Read more at Science Daily

Deadly waves: Researchers document evolution of plague over hundreds of years in medieval Denmark

Scientists who study the origins and evolution of the plague have examined hundreds of ancient human teeth from Denmark, seeking to address longstanding questions about its arrival, persistence and spread within Scandinavia.

In the first longitudinal study of its kind, focusing on a single region for 800 years (between 1000-1800AD), researchers reconstructed Yersinia pestis genomes, the bacterium responsible for the plague, and showed that it was reintroduced into the Danish population from other parts of Europe again and again, perhaps via human movement, with devastating effects.

The historical samples were taken from nearly 300 individuals located at 13 different archaeological sites throughout the country.

"We know that plague outbreaks across Europe continued in waves for approximately 500 years, but very little about its spread throughout Denmark is documented in historical archives," says Ravneet Sidhu, one of the study's lead authors and a graduate student at McMaster's Ancient DNA Centre, where the analysis was conducted.

The McMaster researchers, working with a team of historians and bioarchaeologists in Denmark and Manitoba, performed an in-depth examination of the relatedness and differences between the different strains of plague that were present in Denmark during this time.

They reconstructed and sequenced the genomes of Y. pestis, using fragments teased from ancient teeth, which can preserve traces of blood-borne infection for centuries. They compared the plague genomes to one another and to their modern-day relatives.

Researchers found positive plague samples in 13 individuals who had lived and died over a period of three centuries.

Nine of those samples provided enough genetic information to draw evolutionary conclusions about the plague's persistence in Denmark. The results create a picture of urban and rural populations hammered by relentless waves of plague.

"The high frequency of Y. pestis reintroduction to Danish communities is consistent with the assumption that most deaths in the period were due to newly introduced pathogens. This association between pathogen introduction and mortality illuminates essential aspects of the demographic evolution, not only in Denmark but across the whole European continent," says Jesper L. Boldsen, the skeletal collection curator and paleodemographer at ADBOU, University of Southern Denmark.

The analysis, reported today in the journal Current Biology, revealed that the Danish Y. pestis sequences were interspersed with medieval and early modern strains from other European countries, including the Baltic region and Russia, rather than coming from a single domestic cluster that re-emerged from natural reservoirs over the centuries.

"The evidence for plague in Denmark, both historical and archaeological, has been far more sparse than in some other regions, such as England and Italy. This study identified plague for the first time from medieval Denmark, therefore enabling us to connect the experience in Denmark to disease patterns elsewhere," said Julia Gamble a co-author on the study and assistant professor of anthropology at the University of Manitoba.

In striking detail, researchers describe the earliest known appearance of Y. pestis in Denmark in the town of Ribe dating back to 1333 during the Black Death, its appearance in rural areas such Tirup -- where there is no surviving historical evidence -- and its disappearance by 1649.

Most places it hit in Denmark were port cities, but one of the last outbreaks struck a small rural site in the centre of the country with no access to water, suggesting importation via land.

Plague is a disease of rodents, but clearly the results suggest human-facilitated movement of plague, either via rodents travelling with humans or via other vectors, such as lice, on them.

"The results reveal new connections between past and present experiences of plague, and add to our understanding of the distribution, patterns and virulence of re-emerging diseases," says Hendrik Poinar, senior author of the paper, director of the McMaster Ancient DNA Centre and an investigator with the Michael G. DeGroote Institute for Infectious Disease Research.

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New geosciences study shows Triassic fossils that reveal origins of living amphibians

The smallest of newly found fossils can upend what paleontologists know about our history.

A team of paleontologists from Virginia Tech and the U.S. Petrified Forest National Park, among others, have discovered the first "unmistakable" Triassic-era caecilian fossil -- the oldest-known caecilian fossils -- thus extending the record of this small, burrowing animal by roughly 35 million years. The find also fills a gap of at least 87 million years in the known historical fossil record of the amphibian-like creature.

The fossil was first co-discovered by Ben Kligman, a doctoral student in the Department of Geosciences, part of the Virginia Tech College of Science, at Arizona's Petrified Forest National Park during a dig in 2019. Named by Kligman as Funcusvermis gilmorei, the fossil extends the history of caecilians 35 million years back to Triassic Period, roughly 250 million to 200 million years ago.

Prior to this new study, published today in the journal Nature, only 10 fossil caecilian occurrences were known, dating back to the Early Jurassic Period, about 183 million years ago. However, previous DNA studies estimated evolutionary origins of caecilians back to the Carboniferous or Permian eras, some 370 million to 270 million years ago, according to Kligman, marking that 87-million-year gap. However, no such fossils had been found.

"The discovery of the oldest caecilian fossils highlights the crucial nature of new fossil evidence. Many of the biggest outstanding questions in paleontology and evolution cannot be resolved without fossils like this," said Kligman, who previously discovered a 220-million-year-old species of cynodont or stem-mammal, a precursor of modern-day mammals. "Fossil caecilians are extraordinarily rare, and they are found accidentally when paleontologists are searching for the fossils of other more common animals. Our discovery of one was totally unexpected, and it transformed the trajectory of my scientific interests."

The discovery of the fossils was made in 2019 by Kligman and Petrified Forest National Park student intern Xavier Jenkins, now a Ph.D. student at Idaho State University, while the duo was processing fossiliferous sediment from the park's nicknamed Thunderstorm Ridge via a microscope. Funcusvermis was found in a layer of the Chinle Formation dated to approximately 220 million years ago, when Arizona was positioned near the equator at the central part of the supercontinent Pangaea, Kligman said. This region at the time was subject to a hot, humid climate. Today, Arizona is still hot, but has low humidity.

"Seeing the first jaw under the microscope, with its distinctive double row of teeth, sent chills down my back," Kligman said. "We immediately knew it was a caecilian, the oldest caecilian fossil ever found, and a once-in-a-lifetime discovery."

Previous to this find, the 87-million-year gap in the fossil record hid the early evolutionary history of caecilians, leading to a decades-long debate amongst scientists over the relationships of caecilians to their amphibian relatives, frogs and salamanders.

"Funcusvermis extends the humid equatorial pattern of occurrence seen in all known fossil and living caecilians, suggesting that the biogeographic history of caecilians has been guided by restriction to these ecological settings, likely due to physiological constraints linked to humidity, and constrained by the drift of continental plates into and out of the humid-equatorial zone after the fragmentation of Pangaea," Kligman said.

Modern caecilians are limbless amphibians with cylindrical bodies with a compact, bullet-shaped skull that helps them burrow underground. Now exclusively home to South and Central America, Africa, and southern Asia, caecilians spend their lives burrowing in leaf-litter or soil searching for prey such as worms and insects. This underground existence has made studying caecilians difficult for scientists. Kligman, tongue in cheek, describes modern caecilians as an "eyeless sock puppet with the body of a worm."

Funcusvermis actually shares skeletal features related more with early frog and salamander fossils, strengthening evidence for a shared origin and close evolutionary relationship between caecilians and these two groups. Funcusvermis also shares skeletal features with an ancient group of amphibians known to paleontologists as dissorophoid temnospondyls. Kligman adds, "Unlike living caecilians, Funcusvermis lacks many adaptations associated with burrowing underground, indicating a slower acquisition of features associated with an underground lifestyle in the early stages of caecilian evolution."

Name that tune

Now, here's the fun part: The genus name 'Funcusvermis' was inspired by the Ohio Players' 1972 song "Funky Worm" from their album Pleasure, a favorite song of the authors that was often played while excavating fossils at Thunderstorm Ridge. 'Funcus' is derived from the Latinized form of the English word Funky for the upbeat, rhythmic form of dance music, while 'vermis' is derived from the Latin word for worm. (It's an excellent song, by the way. Instant earworm, so to speak.)

The species name, gilmorei, honors Ned Gilmore, the collections manager at the Academy of Natural Sciences of Philadelphia's Drexel University. (Kligman is from Philadelphia and volunteered with Gilmore's herpetology wet collection as an undergraduate student. "He was an important mentor who helped inspire my interest in fossils and amphibians," Kligman said.)

Co-authors on the study include Michelle Stocker, an assistant professor, and Sterling Nesbitt, an associate professor, in the Virginia Tech Department of Geosciences and members of the Global Change Center that is part of the Fralin Life Sciences Institute. Other authors include Adam Marsh, lead paleontologist; Matthew Smith, museum curator; and William Parker, chief of science and resource management, all at the Petrified Forest National Park; and Bryan Gee, postdoctoral fellow at the University of Washington's Burke Museum and Department of Biology.

"As the eponymous song says, it's the funkiest worm in the world," Marsh quipped.

Stocker added, "What we collect really determines what we can say about which animals that were present, how many of them there were, and what they looked like. Without using these methods for fossil collection and analysis we would be missing out on knowing so many important aspects of this Triassic ecosystem. Now that we have a search image of what bones to look for and how to look for them, it will be exciting to see what other fossil localities preserve these early lissamphibians."

Nesbitt said finds such as this can reset the game board on paleontology, in the best sense of the phrase. "This find clearly demonstrates that some fossils that you can barely see can greatly change our understanding of entire groups that you can see today," he said.

What's happened since 2019

At the Petrified Forest National Park, where the initial discovery was found in 2019, the lower jaws of at least 70 individuals of Funcusvermis have been recovered as of summer 2022, making the area "the most abundant fossil caecilian-producing bonebed ever discovered," Kligman said.

Only a handful of bones of Funcusvermis have been found, including upper and lower jaws, a vertebra, and part of a hind-limb, Kligman said. All of the found bones were disarticulated, not as complete skeletons. Without complete skeletons, Kligman and his fellow researchers cannot exactly determine the body length of Funcusvermis, but inferences from isolated elements, such as the lower jaw being less than a quarter of an inch long, indicate that Funcusvermis was a tiny animal.

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