Paleontology: Diversification after mass extinction

Fossil Fish E. diskosomus.

A team led by Ludwig-Maximilians-Universitaet (LMU) in Munich paleontologist Adriana López-Arbarello has identified three hitherto unknown fossil fish species in the Swiss Alps, which provide new insights into the diversification of the genus Eosemionotus.

Monte San Giorgio in the Swiss canton of Ticino is one of the most important known sources of marine fossils from the Middle Triassic Period (around 240 million years ago). The new and exquisitely preserved fossil fish specimens, which Dr. Adriana López-Arbarello (a member of the Institute of Paleontology and Geobiology and of the Geobiocenter at LMU) has been studying in collaboration with colleagues based in Switzerland were also discovered in these dolomites and limestones. As the researchers now report in the online journal Palaeontologia Electronica, the specimens represent three previously unknown species of Eosemionotus, a genus of ray-finned fishes. "The largest episode of mass extinction in the history of the Earth took place about 250 million years ago," as López-Arbarello explains. "Our finds now provide further evidence that after this catastrophic event, the biosphere recovered relatively fast and went through a period of rapid diversification and the emergence of numerous new species during the Middle Triassic."

The first member of the genus Eosemionotus was discovered in the vicinity of Berlin in 1906, and was named E. vogeli. Almost a century later, in 2004, a second species was described from Monte San Giorgio as E. ceresiensis. Detailed anatomical studies of new material from this locality, carried out by López-Arbarello, have now enabled the recognition of three further species that can be assigned to same genus -- E. diskosomus, E. sceltrichensis and E. minutus. All five species are small in size, but they can be clearly distinguished from each other on the basis of the relative proportions of their bodies, the position of the fins, the morphology of the skull, and the disposition of teeth and scales. "These differences indicate that each species was adapted to different ecological niches," López-Arbarello concludes.

These findings provide new insights into the evolution of the genus. "Our phylogenetic analyses demonstrate that Eosemionotus is the oldest known member of an extinct family within the Order Semionotiformes. Although the Semionotiformes were a species-rich and highly diversified clade during the Mesozoic Era, the order died out in the Cretaceous. Only a few members of its sister group have survived down to the present day, and this ancient lineage is now represented by a single family, the gars," says López-Arbarello.

From Science Daily

Rise of European populism and vaccine hesitancy

There is a significant association between the rise of populism across Europe and the level of mistrust around vaccines, according to a study by Queen Mary University of London.

Lead author Dr Jonathan Kennedy from Queen Mary University of London said: "It seems likely that scientific populism is driven by similar feelings to political populism, for example, a profound distrust of elites and experts by disenfranchised and marginalised parts of the population.

"Even where programmes objectively improve the health of targeted populations, they can be viewed with suspicion by communities that do not trust elites and experts. In the case of vaccine hesitancy, distrust is focused on public health experts and pharmaceutical companies that advocate vaccines."

The study, published in the European Journal of Public Health, looked at national-level data from 14 European countries. This data included the percentage of people in a country who voted for populist parties in the 2014 European Parliament elections, and the percentage of people in a country who believe that vaccines are not important, safe and/or effective, according to data from the 2015 Vaccine Confidence Project.

The analysis found a highly significant positive association between the percentage of people in a country who voted for populist parties and the percentage who believe that vaccines are not important and not effective.

Professor Sophie Harman, an expert on global health politics from Queen Mary's School of Politics and International Relations, who was not involved in the research, commented: "Like restrictions on reproductive rights, anti-vaccination rhetoric has long been the canary in the coal mine for populism."

In the research article, Dr Kennedy writes that modern vaccine hesitancy is usually traced to Andrew Wakefield's now discredited 1998 Lancet article, which claimed a link between the measles, mumps and rubella (MMR) vaccine and autism.

MMR vaccination rates in the UK fell from 92 per cent in 1995 to a low of 79 per cent in 2003, well below the 95 per cent rate needed to achieve herd immunity. Confirmed cases of measles in England and Wales rose from 56 in 1998 to 1370 in 2008.

Wakefield was struck off the UK medical register and the Lancet study retracted. Nevertheless, his ideas remain influential and are cited as a reason why measles cases have increased in Europe over the past few years.

There is additional anecdotal evidence suggesting a connection between the rise of populist politicians and political movements in Western Europe and increasing levels of vaccine hesitancy, Kennedy writes.

The most prominent example is Italy. The Five Star Movement (5SM) have raised concerns about vaccine safety and the link between MMR and autism. It is argued that these concerns caused MMR vaccination coverage to fall from 90 per cent in 2013 to 85 per cent in 2016, and resulted in an increase in measles cases from 840 in 2016 to 5000 in 2017.

Despite this, the upper house of the Italian Parliament -- bolstered by newly elected representatives from 5SM and League -- recently passed a law to repeal legislation that makes vaccines compulsory for children enrolling in state schools.

In France, the right-wing Front National have also raised concerns about vaccine safety and laws that make childhood vaccinations mandatory.

And in Greece, the left-wing SYRIZA government proposed that parents should be able to opt out of vaccinating their children.

While UKIP has not expressed similar concerns, a poll conducted by Mori showed UKIP voters were almost five times more likely than the general population to believe that MMR was unsafe.

Further afield in the US, Donald Trump has met well-known anti-vaccination campaigners, including Wakefield, and expressed sympathy with their ideas. For example, in 2014 he tweeted: 'Healthy young child goes to doctor, gets pumped with massive shot of many vaccines, doesn't feel good and changes -- AUTISM. Many such cases!'

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Using stardust grains, scientists build new model for nova eruptions

What do tiny specks of silicon carbide stardust, found in meteorites and older than the solar system, have in common with pairs of aging stars prone to eruptions?

A collaboration between two Arizona State University scientists -- cosmochemist Maitrayee Bose and astrophysicist Sumner Starrfield, both of ASU's School of Earth and Space Exploration -- has uncovered the connection and pinpointed the kind of stellar outburst that produced the stardust grains.

Their study has just been published in The Astrophysical Journal.

The microscopic grains of silicon carbide -- a thousand times smaller than the average width of a human hair -- were part of the construction materials that built the Sun and planetary system. Born in nova outbursts, which are repeated cataclysmic eruptions by certain types of white dwarf stars, the silicon carbide grains are found today embedded in primitive meteorites.

"Silicon carbide is one of the most resistant bits found in meteorites," Bose said. "Unlike other elements, these stardust grains have survived unchanged from before the solar system was born."

Violent birth

A star becomes a nova -- a "new star" -- when it suddenly brightens by many magnitudes. Novae occur in pairs of stars where one star is a hot, compact remnant called a white dwarf. The other is a cool giant star so large its extended outer atmosphere feeds gas onto the white dwarf. When enough gas collects on the white dwarf, a thermonuclear eruption ensues, and the star becomes a nova.

Although powerful, the eruption doesn't destroy the white dwarf or its companion, so novae can erupt over and over, repeatedly throwing into space gas and dust grains made in the explosion. From there the dust grains merge with clouds of interstellar gas to become the ingredients of new star systems.

The Sun and solar system were born about 4.6 billion years ago from just such an interstellar cloud, seeded with dust grains from earlier stellar eruptions by many different kinds of stars. Almost all the original grains were consumed in making the Sun and planets, yet a tiny fraction remained. Today these bits of stardust, or presolar grains, can be identified in primitive solar system materials such as chondritic meteorites.

"The key that unlocked this for us was the isotopic composition of the stardust grains," Bose said. Isotopes are varieties of chemical elements that have extra neutrons in their nuclei. "Isotopic analysis lets us trace the raw materials that came together to form the solar system."

She added, "Each silicon carbide grain carries a signature of the isotopic composition of its parent star. This provides a probe of that star's nucleosynthesis -- how it made elements."

Bose collected published data on thousands of grains, and found that nearly all the grains grouped naturally into three main categories, each attributable to one kind of star or another.

But there were about 30 grains that couldn't be traced back to a particular stellar origin. In the original analyses, these grains were flagged as possibly originating in nova explosions.

But did they?

Making stardust

As a theoretical astrophysicist, Starrfield uses computer calculations and simulations to study various kinds of stellar explosions. These include novae, recurrent novae, X-ray bursts, and supernovae.

Working with other astrophysicists, he was developing a computer model to explain the ejected materials seen in the spectrum of a nova discovered in 2015. Then he attended a colloquium talk given by Bose before she had joined the faculty.

"I would not have pursued this if I hadn't heard Maitrayee's talk and then had our follow-up discussion," he said. That drew him deeper into the details of nova eruptions in general and what presolar grains could say about these explosions that threw them into space.

A problem soon arose. "After talking with her," Starrfield said, "I discovered our initial way of solving the problem was not agreeing with either the astronomical observations or her results.

"So I had to figure out a way to get around this."

He turned to multidimensional studies of classical nova explosions, and put together a wholly new way of doing the model calculations.

There are two major composition classes of nova, Starrfield said. "One is the oxygen-neon class which I've been working on for 20 years. The other is the carbon-oxygen class which I had not devoted as much attention to." The class designations for novae come from the elements seen in their spectra.

"The carbon-oxygen kind produce a lot of dust as part of the explosion itself," Starrfield said. "The idea is that the nova explosion reaches down into the white dwarf's carbon-oxygen core, bringing up all these enhanced and enriched elements into a region with high temperatures."

That, he said, can drive a much bigger explosion, adding, "It's really messy. It shoots out dust in tendrils, sheets, jets, blobs, and clumps."

Starrfield's calculations made predictions of 35 isotopes, including those of carbon, nitrogen, silicon, sulfur, and aluminum, that would be created by the carbon-oxygen nova outbursts.

It turned out that getting the right proportion of white dwarf core material and accreted material from the companion star was absolutely necessary for the simulations to work. Bose and Starrfield then compared the predictions with the published compositions of the silicon carbide grains.

This led them to a somewhat surprising conclusion. Said Bose, "We found that only five of the roughly 30 grains could have come from novae."

While this may seem a disappointing result, the scientists were actually pleased. Bose said, "Now we have to explain the compositions of the grains that didn't come from nova outbursts. This means there's a completely new stellar source or sources to be discovered."

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New findings shed light on origin of upright walking in human ancestors

This is a fossil hominin talus from site GWM67 (2005) at the time of its discovery.

The oldest distinguishing feature between humans and our ape cousins is our ability to walk on two legs -- a trait known as bipedalism. Among mammals, only humans and our ancestors perform this atypical balancing act. New research led by a Case Western Reserve University School of Medicine professor of anatomy provides evidence for greater reliance on terrestrial bipedalism by a human ancestor than previously suggested in the ancient fossil record.

Scott W. Simpson, PhD, led an analysis of a 4.5 million-year-old fragmentary female skeleton of the human ancestor Ardipithecus ramidus that was discovered in the Gona Project study area in the Afar Regional State of Ethiopia.

The newly analyzed fossils document a greater, but far from perfect, adaptation to bipedalism in the Ar. ramidus ankle and hallux (big toe) than previously recognized. "Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before," said Simpson.

Fossils of this age are rare and represent a poorly known period of human evolution. By documenting more fully the function of the hip, ankle, and foot in Ardipithecus locomotion, Simpson's analysis helps illuminate current understanding of the timing, context, and anatomical details of ancient upright walking.

Previous studies of other Ardipithecus fossils showed that it was capable of terrestrial bipedalism as well as being able to clamber in trees, but lacked the anatomical specializations seen in the Gona fossil examined by Simpson. The new analysis, published in the Journal of Human Evolution, thus points to a diversity of adaptations during the transition to how modern humans walk today. "The fact that Ardipithecus could both walk upright, albeit imperfectly, and scurry in trees marks it out as a pivotal transitional figure in our human lineage," said Simpson.

Key to the adaptation of bipedality are changes in the lower limbs. For example, unlike monkeys and apes, the human big toe is parallel with the other toes, allowing the foot to function as a propulsive lever when walking. While Ardipithecus had an offset grasping big toe useful for climbing in trees, Simpson's analysis shows that it also used its big toe to help propel it forward, demonstrating a mixed, transitional adaptation to terrestrial bipedalism.

Specifically, Simpson looked at the area of the joints between the arch of the foot and the big toe, enabling him to reconstruct the range of motion of the foot. While joint cartilage no longer remains for the Ardipithecus fossil, the surface of the bone has a characteristic texture which shows that it had once been covered by cartilage. "This evidence for cartilage shows that the big toe was used in a more human-like manner to push off," said Simpson. "It is a foot in transition, one that shows primitive, tree-climbing physical characteristics but one that also features a more human-like use of the foot for upright walking." Additionally, when chimpanzees stand, their knees are "outside" the ankle, i.e., they are bow-legged. When humans stand, the knees are directly above the ankle -- which Simpson found was also true for the Ardipithecus fossil.

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Amoebae diversified at least 750 million years ago, far earlier than expected

Reconstitution of Amoebozoa's evolution shows significant Precambrian species diversity. This study changes the view of how life evolved in the very remote past and deepens the understanding of current climate change (a Thecamoebian protist of genus Cyclopixys)

Brazilian researchers have reconstructed the evolutionary history of amoebae and demonstrated that at the end of the Precambrian period, at least 750 million years ago, life on Earth was much more diverse than suggested by classic theory.

The study, which was supported by São Paulo Research Foundation -- FAPESP, revealed eight new ancestral lineages of Thecamoebae, the largest group in Amoebozoa. Thecamoebians are known as testates because of their hard outer carapace or shell.

Interpretations of the evolution of Earth's atmosphere and climate change are also affected by the discovery that amoebae are more diverse than previously thought.

In this study, published in the journal Current Biology, researchers affiliated with the University of São Paulo's Bioscience Institute (IB-USP) in Brazil, in partnership with colleagues at the Mississippi State University in the United States, used innovative techniques to reconstruct the phylogenetic (evolutionary) tree of Thecamoeba, which belongs to the order Arcellinida.

The new phylogenetic tree was created using mathematical algorithms and the transcriptomes of 19 arcellinids found in nature today. The researchers also established the morphology and composition of the hypothetical ancestors of this group of amoebae and compared them with the fossil record.

The results showed that at least 750 million years ago, ancestors of the thecamoebians were already evolving. This finding indicates that the late Precambrian was more diverse than previously thought.

"We reached our conclusions using a combination of two major scientific areas -- paleontology and phylogenetic systematics, the field within biology that reconstructs evolutionary history and studies the patterns of relationships among organisms. In this way, we were able to untangle one of the knots in evolutionary theory about life on the planet," said Daniel Lahr, a professor at IB-USP and lead author of the article.

Reclassification of Amoebozoa

The researchers completely dismantled the previous classification of thecamoebians. "We succeeded in developing a robust structure and for the first time, discovered eight deep lineages [from 750 million years ago] of arcellinids about which nothing was known," Lahr told.

The old thecamoebian classification was based on shell composition. "They were divided into agglutinate and organic. However, from our molecular reconstruction, we discovered that the classification is actually determined by shell shape rather than composition," Lahr said.

The old classification, he added, had been questioned for several years, but more evidence was needed to demolish it. Previous genetic research has shown that the classification was unsustainable, but not enough data were available to justify a new classification.

"The scientific community suspected that the arcellinid testate amoebae had emerged and evolved sufficiently to diversify some 750 million years ago. We've now succeeded in demonstrating this hypothesis," he said.

Past and future

According to Lahr, the study presents a different view of how microorganisms evolved on the planet. The late Precambrian was considered a period of low biotic diversity, with only a few species of bacteria and some protists.

"It was in this period 800 million years ago that the oceans became oxygenated. For a long time, oxygenation was assumed to have led to diversification of the eukaryotes, unicellular and multicellular organisms in which the cell's nucleus is isolated by a membrane, culminating in the diversification of macroorganisms millions of years later in the Cambrian," Lahr said.

The study published in Current Biology, he added, focuses on a detail of this question. "We show that diversification apparently already existed in the Precambrian and that it probably occurred at the same time as ocean oxygenation. What's more, geophysicists are discovering that this process was slow and may have lasted 100 million years or so," he said.

However, scientists do not know what pressure triggered this oxygenation. "Regardless of the cause, oxygenation eventually led to more niches, the eukaryotes diversified, and there was more competition for niches. One way to resolve the competition was for some lineages to become larger and hence multicellular," Lahr said.

The study has also contributed to a better understanding of today's climate change. "We began to understand in more depth how this microbial life affected the planet in several ways," Lahr said. "The climate changed in fundamental ways during the period, which saw the occurrence of the Sturtian glaciation some 717 million years ago. This was one of the largest glaciation events ever."

According to Lahr, these changes may have had biological origins. "By increasing the resolution of how life evolved in the very remote past, we can understand a little better how life affects the planet's climate and even its geology. That will help us understand the climate changes we're currently experiencing," he said.

In rock

In addition to the discovery of greater diversity in the Precambrian, the study also innovates by reconstructing the morphology of the ancestors of thecamoebians to establish that the vase-shaped microfossils (VSMs) found in various parts of the world already existed in the Precambrian and even in the major ice ages that occurred during this era.

VSMs are presumed to be fossils of testate amoebae. They are unicellular and eukaryotic and have an external skeleton. Significant diversity of VSMs has been documented for the Neoproterozoic Era, which spanned between 1 billion and 541 million years ago, and was the terminal era of the Precambrian.

"The study constitutes a very different vision of how microorganisms evolved on the planet. Although the fossils do not contain genetic information, it is possible to obtain morphological and compositional information and to verify whether they are organic or silica-based. So it's possible to compare their shape and chemical composition, which in this case are especially well preserved, with those of current thecamoebians reconstituted by big data," said Luana Morais, a postdoctoral researcher with a scholarship from FAPESP and coauthor of the article.

Innovative techniques

In addition to the lack of DNA-containing fossils, the researchers faced another obstacle in reconstructing the phylogenetic tree: thecamoebians cannot be cultured in the laboratory, and genetic sequencing by conventional means is therefore ruled out.

The solution to this problem was to use the single-cell transcriptome technique to analyze phylogenetics (instead of gene expression, its normal application). "We sequenced whole transcriptomes of arcellinid amoebae using live samples," Lahr explained. "This yielded several thousand genes and some 100,000 amino acid sites, or 100,000 datapoints giving us the phylogenetic tree, which had never been seen before."

The researchers used transcriptome-based methodology to capture all messenger RNAs from each individual cell and convert them into a sequenceable complementary DNA library.

"Our research drew fundamentally on single-cell transcriptomics, in which our lab is one of the worldwide pioneers," Lahr said. "It's a revolutionary technique in this field because it enables us to find a single [unicellular] amoeba, isolate and clean it, and perform all the laboratory procedures to sequence the whole transcriptome."

In this study, the researchers selected 250 genes to construct the phylogenetic tree. "It's no good looking at only one cell when you're studying gene expression, because the resolution will be insufficient," Lahr said. "In an evolutionary study, however, this doesn't matter. You need to obtain the sequence, not the number of times a gene is expressed. So it's possible to use this technique, which was originally developed for tumor cells, and adapt it, with the advantage that an amoeba cell is much larger than a tumor cell."

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Crater counts on Pluto, Charon show small Kuiper Belt objects surprisingly rare

An SwRI-led team studied the craters and geology on Pluto and Charon and found there were fewer small craters than expected. This implies that the Kuiper Belt contains relatively small numbers of objects less than 1 mile in diameter. Imaged by New Horizon's LORRI camera, the smooth, geologically stable 'Vulcan Planitia' on Charon illustrates these findings.

Using New Horizons data from the Pluto-Charon flyby in 2015, a Southwest Research Institute-led team of scientists have indirectly discovered a distinct and surprising lack of very small objects in the Kuiper Belt. The evidence for the paucity of small Kuiper Belt objects (KBOs) comes from New Horizons imaging that revealed a dearth of small craters on Pluto's largest satellite, Charon, indicating that impactors from 300 feet to 1 mile (91 meters to 1.6 km) in diameter must also be rare.

The Kuiper Belt is a donut-shaped region of icy bodies beyond the orbit of Neptune. Because small Kuiper Belt objects were some of the "feedstock" from which planets formed, this research provides new insights into how the solar system originated. This research was published in the March 1 issue of the journal Science.

"These smaller Kuiper Belt objects are much too small to really see with any telescopes at such a great distance," said SwRI's Dr. Kelsi Singer, the paper's lead author and a co-investigator of NASA's New Horizons mission. "New Horizons flying directly through the Kuiper Belt and collecting data there was key to learning about both large and small bodies of the Belt."

"This breakthrough discovery by New Horizons has deep implications," added the mission's principal investigator, Dr. Alan Stern, also of SwRI. "Just as New Horizons revealed Pluto, its moons, and more recently, the KBO nicknamed Ultima Thule in exquisite detail, Dr. Singer's team revealed key details about the population of KBOs at scales we cannot come close to directly seeing from Earth."

Craters on solar system objects record the impacts of smaller bodies, providing hints about the history of the object and its place in the solar system. Because Pluto is so far from Earth, little was known about the dwarf planet's surface until the epic 2015 flyby. Observations of the surfaces of Pluto and Charon revealed a variety of features, including mountains that reach as high as 13,000 feet (4 km) and vast glaciers of nitrogen ice. Geologic processes on Pluto have erased or altered some of the evidence of its impact history, but Charon's relative geologic stasis has provided a more stable record of impacts.

"A major part of the mission of New Horizons is to better understand the Kuiper Belt," said Singer, whose research background studying the geology of the icy moons of Saturn and Jupiter positions her to understand the surface processes seen on KBOs. "With the successful flyby of Ultima Thule early this year, we now have three distinct planetary surfaces to study. This paper uses the data from the Pluto-Charon flyby, which indicate fewer small impact craters than expected. And preliminary results from Ultima Thule support this finding."

Typical planetary models show that 4.6 billion years ago, the solar system formed from the gravitational collapse of a giant molecular cloud. The Sun, the planets and other objects formed as materials within the collapsing cloud clumped together in a process known as accretion. Different models result in different populations and locations of objects in the solar system.

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Oldest tattoo tool in western North America

This is a close up of a 2,000-year-old cactus spine tattoo tool discovered by WSU archaeologist Andrew Gillreath-Brown.

Washington State University archaeologists have discovered the oldest tattooing artifact in western North America.

With a handle of skunkbush and a cactus-spine business end, the tool was made around 2,000 years ago by the Ancestral Pueblo people of the Basketmaker II period in what is now southeastern Utah.

Andrew Gillreath-Brown, an anthropology PhD candidate, chanced upon the pen-sized instrument while taking an inventory of archaeological materials that had been sitting in storage for more than 40 years.

He is the lead author of a paper on the tattoo tool which was published today in the Journal of Archaeological Science: Reports.

His discovery pushes back the earliest evidence of tattooing in western North America by more than a millennium and gives scientists a rare glimpse into the lives of a prehistoric people whose customs and culture have largely been forgotten.

"Tattooing by prehistoric people in the Southwest is not talked about much because there has not ever been any direct evidence to substantiate it," Gillreath-Brown, 33, said. "This tattoo tool provides us information about past Southwestern culture we did not know before."

Tattooing is an artform and mode of expression common to many indigenous cultures worldwide. However, little is known about when or why the practice began.

This is especially the case in places like the southwestern United States, where no tattoos have been identified on preserved human remains and there are no ancient written accounts of the practice.

Instead, archaeologists have relied on visual depictions in ancient artwork and the identification of tattoo implements to trace the origins of tattooing in the region.

Previously, bundled and hafted, or handled, cactus spine tattoo tools from Arizona and New Mexico provided the best archaeological examples of early tattoo implements from the Southwest. The earliest of these have been dated to between AD 1100-1280.

So when Gillreath-Brown came across a very similar looking implement from a site in Utah that is 1,000 years older, he knew he had found something special.

"When I first pulled it out of the museum box and realized what it might have been I got really excited," said Gillreath-Brown, who himself wears a large sleeve tattoo of a turtle shell rattle, mastodon, water, and forest on his left arm.

The tool consists of a 3 ½ inch wooden skunkbush sumac handle bound at the end with split yucca leaves and holding two parallel cactus spines, stained black at their tips.

"The residue staining from tattoo pigments on the tip was what immediately piqued my interest as being possibly a tattoo tool," Gillreath-Brown said.

Encouraged by Aaron Deter-Wolf, a friend and co-author of the study who had done ancient tattooing and edited several books on the subject, Gillreath-Brown analyzed the tips with a scanning electron microscope, X-ray florescence and energy dispersive ray spectroscopy. For good measure, he did several test tattoos using a replica on pig skin.

He saw the crystalline structure of pigment and determined it likely contained carbon, a common element in body painting and tattooing.

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500-million-year old worm 'superhighway' discovered in Canada

These are worm tunnels (labelled) visible in small section of rock.

Prehistoric worms populated the sea bed 500 million years ago -- evidence that life was active in an environment thought uninhabitable until now, research by the University of Saskatchewan (USask) shows.

The sea bed in the deep ocean during the Cambrian period was thought to have been inhospitable to animal life because it lacked enough oxygen to sustain it.

But research published in the scientific journal Geology reveals the existence of fossilized worm tunnels dating back to the Cambrian period -- 270 million years before the evolution of dinosaurs.

The discovery, by USask professor Brian Pratt, suggests that animal life in the sediment at that time was more widespread than previously thought.

The worm tunnels -- borrows where worms lived and munched through the sediment -- are invisible to the naked eye. But Pratt "had a hunch" and sliced the rocks and scanned them to see whether they revealed signs of ancient life.

The rocks came from an area in the remote Mackenzie Mountains of the Northwest Territories in Canada which Pratt found 35 years ago.

Pratt then digitally enhanced images of the rock surfaces so he could examine them more closely. Only then did the hidden 'superhighway' of burrows made by several different sizes and types of prehistoric worm emerge in the rock.

Some were barely a millimetre in size and others as large as a finger. The smaller ones were probably made by simple polychaetes -- or bristle worms -- but one of the large forms was a predator that attacked unsuspecting arthropods and surface-dwelling worms.

Pratt said he was "surprised" by the unexpected discovery.

"For the first time, we saw evidence of large populations of worms living in the sediment -- which was thought to be barren," he said. "There were cryptic worm tunnels -- burrows -- in the mud on the continental shelf 500 million years ago, and more animals reworking, or bioturbating, the sea bed than anyone ever thought."

Pratt, a geologist and paleontologist and Fellow of the Geological Society of America, found the tunnels in sedimentary rocks that are similar to the Burgess Shale, a famous fossil-bearing deposit in the Canadian Rockies.

The discovery may prompt a rethink of the level of oxygenation in ancient oceans and continental shelves.

The Cambrian period saw an explosion of life on Earth in the oceans and the development of multi-cellular organisms including prehistoric worms, clams, snails and ancestors of crabs and lobsters. Previously the seas had been inhabited by simple, single-celled microbes and algae.

It has always been assumed that the creatures in the Burgess Shale -- known for the richness of its fossils -- had been preserved so immaculately because the lack of oxygen at the bottom of the sea stopped decay, and because no animals lived in the mud to eat the carcasses.

Pratt's discovery, with co-author Julien Kimmig, now of the University of Kansas, shows there was enough oxygen to sustain various kinds of worms in the sea bed.

"Serendipity is a common aspect to my kind of research," Pratt said. "I found these unusual rocks quite by accident all those years ago. On a hunch I prepared a bunch of samples and when I enhanced the images I was genuinely surprised by what I found," he said.

"This has a lot of implications which will now need to be investigated, not just in Cambrian shales but in younger rocks as well. People should try the same technique to see if it reveals signs of life in their samples."

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Hiding black hole found

This is an artist's impression of a gas cloud swirling around a black hole.

Astronomers have detected a stealthy black hole from its effects on an interstellar gas cloud. This intermediate mass black hole is one of over 100 million quiet black holes expected to be lurking in our Galaxy. These results provide a new method to search for other hidden black holes and help us understand the growth and evolution of black holes.

Black holes are objects with such strong gravity that everything, including light, is sucked in and cannot escape. Because black holes do not emit light, astronomers must infer their existence from the effects their gravity produces in other objects. Black holes range in mass from about 5 times the mass of the Sun to supermassive black holes millions of times the mass of the Sun. Astronomers think that small black holes merge and gradually grow into large ones, but no one had ever found an intermediate mass black hole, hundreds or thousands of times the mass of the Sun.

A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan noticed HCN-0.009-0.044, a gas cloud moving strangely near the center of the Galaxy 25,000 light-years away from Earth in the constellation Sagittarius. They used ALMA (Atacama Large Millimeter/submillimeter Array) to perform high resolution observations of the cloud and found that it is swirling around an invisible massive object.

Takekawa explains, "Detailed kinematic analyses revealed that an enormous mass, 30,000 times that of the Sun, was concentrated in a region much smaller than our Solar System. This and the lack of any observed object at that location strongly suggests an intermediate-mass black hole. By analyzing other anomalous clouds, we hope to expose other quiet black holes."

Tomoharu Oka, a professor at Keio University and coleader of the team, adds, "It is significant that this intermediate mass black hole was found only 20 light-years from the supermassive black hole at the Galactic center. In the future, it will fall into the supermassive black hole; much like gas is currently falling into it. This supports the merger model of black hole growth."

From Science Daily

Exiled planet linked to stellar flyby 3 million years ago

The HD 106906 binary star hosts a mysterious, asymmetric disk of cometary dust and a giant exoplanet HD 106906 b that is located very far from both the binary and the disk. Close flybys by other stars could have gravitationally perturbed the planet and researchers discovered that the two bright stars to the upper right passed near HD 106906 roughly 3 Myr years ago.

Some of the peculiar aspects of our solar system -- an enveloping cloud of comets, dwarf planets in weird orbits and, if it truly exists, a possible Planet Nine far from the sun -- have been linked to the close approach of another star in our system's infancy flung things helter-skelter.

But are stellar flybys really capable of knocking planets, comets and asteroids askew, reshaping entire planetary systems?

UC Berkeley and Stanford University astronomers think they have now found a smoking gun.

A planet orbiting a young binary star may have been perturbed by another pair of stars that skated too close to the system between 2 and 3 million years ago, soon after the planet formed from a swirling disk of dust and gas.

If confirmed, this bolsters arguments that close stellar misses help sculpt planetary systems and may determine whether or not they harbor planets with stable orbits.

"One of the mysteries arising from the study of exoplanets is that we see systems where the planets are misaligned, even though they are born in a flat, circular disk," said Paul Kalas, a UC Berkeley adjunct professor of astronomy. "Maybe a cosmic tsunami hit these systems and rearranged everything about them, but we haven't had proof. Our paper gives rare observational evidence for one of these flybys gently influencing one of the planetary systems in the galaxy."

Astronomers are already searching for a stellar flyby in our solar system's past, but since that likely happened 4.6 billion years ago, most of the evidence has gone cold. The star system that the astronomers studied, identified only by the number HD 106906 and located about 300 light years from Earth in the direction of the constellation Crux, is very young, only about 15 million years old.

Kalas and Robert De Rosa, a former UC Berkeley postdoc who is now a research scientist at Stanford's Kavli Institute for Particle Astrophysics and Cosmology, describe their findings in a paper accepted for publication in the Astronomical Journal and now available online.

Rogue stars

Kalas, who studies young, newly formed planetary systems to try to understand what happened in the early years of our own solar system, first focused on HD 106906 in 2015 after it was found to have a massive planet in a highly unusual orbit. The planet, dubbed HD 106906 b, has a mass of about 11 Jupiters, and it orbits HD 106906 -- recently revealed to be a binary star -- in an orbit tipped about 21 degrees from the plane of the disk that contains all the other material around the star. Its current location is at least 738 times farther from its star than Earth is from the sun, or about 18 times farther from its star than Pluto is from the sun.

Kalas used both the Gemini Planet Imager on the Gemini Telescope in the Chilean Andes and the Hubble Space Telescope to look more closely at HD 106906 and discovered that the star has a lopsided comet belt, as well. The planet's strange orbit and the fact that the dust disk itself is asymmetrical indicated that something had disrupted the young system.

Kalas and his colleagues, including De Rosa, proposed that the planet had been kicked out of its solar system by interactions with another as-yet-unseen planet in the system or by a passing star. Kalas and De Rosa now believe that both happened: The planet was kicked into an eccentric orbit when it came dangerously close to the central binary star, a scenario proposed in 2017 by theorist Laetitia Rodet and her collaborators from the Grenoble Observatory in France. Repeated gravitational kicks from the binary would have quickly ejected the planet into interstellar space, but the passing stars rescued the planet by nudging its orbit to a safer distance from the binary.

The Gaia space observatory gave them the data they needed to test their hypothesis. Gaia, launched in 2012 by the European Space Agency, collects precise measurements of distance, position and motion for 1.3 billion stars in the Milky Way Galaxy, a catalog 10,000 times larger than Gaia's predecessor, Hipparcos.

Kalas and De Rosa gathered Gaia information on 461 stars in the same cluster as HD 106906 and calculated their positions backward in time -- reversed the cosmic clock, so to speak -- and discovered that another binary star system may have approached close enough 3 million years ago to alter the planetary system.

"What we have done here is actually find the stars that could have given HD 106906 b the extra gravitational kick, a second kick so that it became long-lived, just like a hypothetical Planet Nine would be in our solar system," Kalas said.

They also found also that the binary star came in on a trajectory that was within about 5 degrees of the system's disk, making it even more likely that the encounter had a strong and lasting impact on HD 106906.

Such double kicks may be important to stabilizing planets, asteroids and comets around stars, Kalas said.

"Studying the HD 106906 planetary system is like going back in time to watch the Oort cloud of comets forming around our young sun," he said. "Our own giant planets gravitationally kicked countless comets outward to large distances. Many were ejected completely, becoming interstellar objects like ?Oumuamua, but others were influenced by passing stars. That second kick by a stellar flyby can detach a comet's orbit from any further encounters with the planets, saving it from the prospect of ejection. This chain of events preserved the most primitive solar system material in a deep freeze far from the sun for billions of years."

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First semi-identical twins identified in pregnancy

Illustration shows two sperm fertilizing an egg.

Young Brisbane twins, a boy and a girl, have been identified as only the second set of semi-identical, or sesquizygotic, twins in the world -- and the first to be identified by doctors during pregnancy.

"It is likely the mother's egg was fertilised simultaneously by two of the father's sperm before dividing," said Professor Fisk, who led the fetal medicine team that cared for the mother and twins while based at Royal Brisbane and Women's Hospital in 2014. Professor Fisk, a past President of the International Fetal Medicine and Surgery Society, worked alongside Dr Gabbett.

"The mother's ultrasound at six weeks showed a single placenta and positioning of amniotic sacs that indicated she was expecting identical twins. However, an ultrasound at 14 weeks showed the twins were male and female, which is not possible for identical twins."

Identical twins result when cells from a single egg fertilised by a single sperm divide into two, so identical twins are the same gender and share identical DNA. Fraternal twins occur when each twin develops from a separate egg and the egg is fertilised by its own sperm.

Dr Gabbett said if one egg is fertilised by two sperm it results in three sets of chromosomes, one from the mother and two from the father.

"Three sets of chromosomes are typically incompatible with life and embryos do not usually survive," he said.

"In the case of the Brisbane sesquizygotic twins, the fertilised egg appears to have equally divided up the three sets of chromosomes into groups of cells which then split into two, creating the twins.

"Some of the cells contain the chromosomes from the first sperm while the remaining cells contain chromosomes from the second sperm, resulting in the twins sharing only a proportion rather 100 per cent of the same paternal DNA."

Sesquizygotic twins were first reported in the US in 2007. Those twins came to doctors' attention in infancy after one was identified with ambiguous genitalia. On investigation of mixed chromosomes, doctors found the boy and girl were identical on their mother's side but shared around half of their paternal DNA.

Professor Fisk said an analysis of worldwide twin databases pointed to just how rare sesquizygotic twins are.

"We at first questioned whether there were perhaps other cases which had been wrongly classified or not reported, so examined genetic data from 968 fraternal twins and their parents," he said.

"However we found no other sesquizygotic twins in these data, nor any case of semi-identical twins in large global twin studies.

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Migrating blue whales rely on memory more than environmental cues to find prey

Photograph of blue whale taken during Oregon State University Marine Mammal Institutes 2016 tagging field season off southern California.

Blue whales reach their massive size by relying on their exceptional memories to find historically productive feeding sites rather than responding in real time to emerging prey patches, a new study concludes.

Researchers examining records of both whale migration and oceanic conditions in the California Current Ecosystem found that blue whales almost perfectly match the timing of their migration to the historical average timing of krill production, rather than matching the waves of krill availability in any given year.

The findings suggest that blue whales locate prey by relying on memory to return to stable, high-quality foraging sites, which historically have served them well but could make it difficult for the whales to adapt if novel ecosystem changes emerge as a result of climate change.

Results of the study are being published next week in Proceedings of the National Academy of Sciences.

The concept of tracking the timing of food availability along migration routes is not unusual for land animals, but it has been more difficult to identify in marine creatures, according to Briana Abrahms, a research ecologist with the NOAA Southwest Fisheries Science Center in Monterey, Calif., and lead author on the study.

"We know that many species that migrate on land, from caribou in the Arctic to wildebeests in the Serengeti, enhance their survival by carefully adjusting the pace and timing of their migrations to find food as it becomes seasonally available along the way, rather than just migrating to get from point A to point B," Abrahms said.

Blue whales seem to embrace that same strategy, which is enhanced by their memory, she noted. "These long-lived, highly intelligent animals are making movement decisions based on their expectations of where and when food will be available during their migrations."

"This novel study is particularly noteworthy in that if focuses on the phenology, or timing of migration in a large marine predator," said Sue Moore, an affiliate professor at the University of Washington Center for Ecosystem Sentinels, who was not involved in the study.

The study also raises the question of what will happen to the population if changing climate conditions cause food availability to deviate strongly from the whales' expectations.

The interdisciplinary research team used 10 years of tagging data from the Marine Mammal Institute at Oregon State University to determine daily blue whale movements of 60 individual whales in the California Current Ecosystem, and then compared that with satellite-based measurements of ocean productivity.

"We think that blue whales have evolved to use historical migration routes and timing that put them in proximity to the most predictably high production feeding areas and then make minor adjustments based on local conditions," said Daniel Palacios, a principal investigator with Oregon State's Marine Mammal Institute and a co-author on the study.

"There are various time scales of events that could change the timing of phytoplankton blooms -- and thus the availability of the whales' preferred prey, krill," he noted, "including La Nina and El Nino events and the Pacific Decadal Oscillation. But the whales' strategy of relying on memory and historic timing at least gets them into 'the Goldilocks zone.'"

Blue whales can grow to the length of a basketball court, weigh as much as 25 large elephants, and their mouths can hold 100 people, though their diet is primarily krill -- tiny shrimp-like creatures less than two inches in length. The blue whale is thought to be the largest creature to ever inhabit the Earth, yet little was known about their range or where they went to breed until Oregon State's Bruce Mate led a series of tracking studies featured in the popular 2009 National Geographic documentary, "Kingdom of the Blue Whale."

"There is still a lot we don't know about blue whales, but it is apparent that they have strong fidelity to certain sites along the West Coast of the United States, which they use year after year," said Mate, who directs OSU's Marine Mammal Institute.

An estimated 2,500 of the world's 10,000 blue whales spend time in the waters off the West Coast of the Americas and are known as the eastern North Pacific population. The huge whales can travel from the Gulf of Alaska all the way down to an area near the equator known as the Costa Rica Dome. The majority of the population spends the summer and fall in the waters off the U.S. West Coast, with the tagged whales most heavily using areas off Santa Barbara and San Francisco, California, which puts them in routine peril from ship strikes.

"We still have a lot to learn about how large animals navigate in the ocean, how they find good habitat and how they are affected by human activities and environmental changes," said NOAA's Abrahms.

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Dark matter may be hitting the right note in small galaxies

Astronomers observed that the dark matter does not seem to clump very much in small galaxies, but their density peaks sharply in bigger systems such as clusters of galaxies. It has been a puzzle why different systems behave differently.

Dark matter may scatter against each other only when they hit the right energy, say researchers in Japan, Germany, and Austria in a new study. Their idea helps explain why galaxies from the smallest to the biggest have the shapes they do.

Dark matter is a mysterious and unknown form of matter that comprises more than 80 per cent of matter in the Universe today. Its nature is unknown, but it is believed to be responsible for forming stars and galaxies by its gravitational pull, which led to our existence.

"Dark matter is actually our mom who gave birth to all of us. But we haven't met her; somehow, we got separated at birth. Who is she? That is the question we want to know," says paper author Hitoshi Murayama, a University of California Berkeley Professor and Kavli Institute for the Physics and Mathematics of the Universe Principal Investigator.

Astronomers have already found dark matter does not seem to clump together as much as computer simulations suggest. If gravity is the only force that drives dark matter, only pulling and never pushing, then dark matter should become very dense towards the center of galaxies. However, especially in small faint galaxies called dwarf spheroidals, dark matter does not seem to become as dense as expected toward their centers.

This puzzle could be solved if dark matter scatters with each other like billiard balls, allowing them to spread out more evenly after a collision.

But one problem with this idea is that dark matter does seem to clump in bigger systems such as clusters of galaxies. What makes dark matter behave differently between dwarf spheroidals and clusters of galaxies? An international team of researchers has developed an explanation that could solve this riddle, and reveal what dark matter is.

"If dark matter scatters with each other only at a low but very special speed, it can happen often in dwarf spheroidals where it is moving slowly, but it is rare in clusters of galaxies where it is moving fast. It needs to hit a resonance" says Chinese physicist Xiaoyong Chu, a postdoctoral researcher at the Austrian Academy of Sciences.

Resonance is a phenomenon that appears every day. To swirl wine in a glass to get it more oxygen so that it lets out more aroma and softens its taste, you need to find the right speed to circle the wine glass. Or you dial old analog radios to the right frequency to tune into your favorite station. These are all examples of resonance, says Murayama. The team suspects this is precisely what dark matter is doing.

"As far as we know, this is the simplest explanation to the puzzle. We are excited because we may know what dark matter is sometime soon," says Murayama.

However, the team was not convinced that such a simple idea would explain the data correctly.

"First, we were a bit skeptical that this idea will explain the observational data; but once we tried it, it worked like a charm!" says Colombian researcher Camilo Garcia Cely, a postdoctoral researcher at the Deutsches Elektronen-Synchrotron (DESY) in Germany.

The team believes it is no accident that dark matter can hit the exact right note.

"There are many other systems in nature that show similar accidents: in stars alpha particles hit a resonance of beryllium, which in turn hits a resonance of carbon, producing the building blocks that gave rise to life on Earth. A similar process happens for a subatomic particle called phi," says Garcia Cely.

"It may also be a sign that our world has more dimensions than we see. If a particle moves in extra dimensions, it has energy. For us who don't see the extra dimension, we think the energy is actually a mass, thanks to Einstein's E=mc2. Perhaps some particle moves twice as fast in extra dimension, making its mass precisely twice as much as the mass of dark matter," says Chu.

The team's next step will be to find observational data that backs their theory.

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Oldest frog relative found in North America

Virginia Tech Assistant Professor Michelle Stocker holds a rock with an enbedded Chinle frog hipbone fossil. The size of an eyelash -- look for the small brownish line with a dot at the bottom -- the fossil was found in Arizona.

A team of paleontologists led by Virginia Tech's Michelle Stocker and Sterling Nesbitt of the Department of Geosciences have identified fossil fragments of what are thought to be the oldest known frogs in North America.

The fossils are comprised of several small pieces of hip bone, called an ilium, from Chinle frogs, a distant long-extinct branch of, but not a direct ancestor of, modern frogs. The fragments are packed into rock and are smaller than a pinky nail. They represent the first known and earliest equatorial remains of a salientian -- the group containing living frogs, and their most-closely related fossil relatives -- from the Late Triassic, roughly 216 million years ago.

The name of the fossil derives from where they were found, the Chinle Formation of Arizona.

Stocker, an assistant professor of geosciences in the Virginia Tech College of Science, says the fossils, discovered in May 2018, underscore the importance of microfossil collection and analysis for understanding extinct species whose total length is under three feet in length.

"This new find highlights just how much there is still to learn about the Late Triassic ecosystem, and how much we find when we just look a little closer," Stocker said. "We're familiar with the charismatic archosaurs from the Chinle Formation, but we know that based on other ecosystems, they should make up a small percentage of the animals that lived together. With this new focus we're able to fill in a lot of those missing smaller components with new discoveries."

Coming from multiple individuals, the hip bones are are long and hollow, with a hip socket offset rather than centered. The bones of the frogs show how tiny they were: Just a bit over half-an-inch long. "The Chinle frog could fit on the end of your finger," Stocker added.

Stocker and her team include researchers from Virginia Tech, Arizona's Petrified Forest National Park, and the University of Florida's Museum of Natural History, with the findings published today in the online journal Biology Letters. Even though the fossils are part of the Chinle frog family, they are not yet naming the specific fossils.

"We refrain from naming this Chinle frog because we are continuing to process microvertebrate matrix that will likely yield additional skull and postcranial material that has the potential to be even more informative," Stocker added.

The Chinle frog shares more features with living frogs and Prosalirus, an Early Jurassic frog found in sediments from the present-day Navajo Nation, than to Triadobatrachus, an Early Triassic frog found in modern day Madagascar in Africa. "These are the oldest frogs from near the equator," Stocker added. "The oldest frogs overall are roughly 250 million years old from Madagascar and Poland, but those specimens are from higher latitudes and not equatorial."

Added Nesbitt, also an assistant professor of geosciences, "Now we know that tiny frogs were present approximately 215 million years ago from North America, we may be able to find other members of the modern vertebrate communities in the Triassic Period."

(During the Triassic, the separate continents we recognize today formed the single landmass named Pangaea. Present-day Arizona was located roughly 10 degrees north of the equator.)

The team added this discovery also marks the first time that frog fossils have been found directly with phytosaurs, and other early dinosaurs.

The Virginia Tech team included both undergraduate and graduate students from across the university, using fossils found in the field and dousing additional rock samples repeatedly in water buckets. Further study of the fossils was completed by CT scans. The undergraduates who accompanied Stocker and Nesbitt on the spring 2018 expedition to Arizona included Elizabeth Evans, a major in the School of Performing Arts; Rebecca Hawkins, majoring in the Department of Fish and Wildlife Conservation; and Hector Lopez, majoring in biological sciences.

"Through my internship with Drs. Stocker and Nesbitt in Arizona, I learned firsthand the hard work that paleontologists put into finding fossils," said Hawkins, a sophomore in the College of Natural Resources and Environment. "Every day you have to brave long treks, heavy loads, scorching heat, and more. But, with just the right combination of patience and luck, you can find something truly amazing that makes the toil worth it, like a tiny frog hip that tells a big story."

"Our development of methods that recover delicate bones from small-bodied vertebrates enabled this exciting discovery," said Ben Kligman, a Ph.D. student in Geosciences from Philadelphia, Pennsylvania. "Our aim is to use similar techniques in the Chinle Formation to uncover the early history of other small-bodied animals including lizards, salamanders, turtles, and mammals."

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Climate rewind: Scientists turn carbon dioxide back into coal

A schematic illustration showing how liquid metal is used as a catalyst for converting carbon dioxide into solid coal.

Researchers have used liquid metals to turn carbon dioxide back into solid coal, in a world-first breakthrough that could transform our approach to carbon capture and storage.

The research team led by RMIT University in Melbourne, Australia, have developed a new technique that can efficiently convert CO2 from a gas into solid particles of carbon.

Published in the journal Nature Communications, the research offers an alternative pathway for safely and permanently removing the greenhouse gas from our atmosphere.

Current technologies for carbon capture and storage focus on compressing CO2 into a liquid form, transporting it to a suitable site and injecting it underground.

But implementation has been hampered by engineering challenges, issues around economic viability and environmental concerns about possible leaks from the storage sites.

RMIT researcher Dr Torben Daeneke said converting CO2 into a solid could be a more sustainable approach.

"While we can't literally turn back time, turning carbon dioxide back into coal and burying it back in the ground is a bit like rewinding the emissions clock," Daeneke, an Australian Research Council DECRA Fellow, said.

"To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable.

"By using liquid metals as a catalyst, we've shown it's possible to turn the gas back into carbon at room temperature, in a process that's efficient and scalable.

"While more research needs to be done, it's a crucial first step to delivering solid storage of carbon."

How the carbon conversion works

Lead author, Dr Dorna Esrafilzadeh, a Vice-Chancellor's Research Fellow in RMIT's School of Engineering, developed the electrochemical technique to capture and convert atmospheric CO2 to storable solid carbon.

To convert CO2, the researchers designed a liquid metal catalyst with specific surface properties that made it extremely efficient at conducting electricity while chemically activating the surface.

The carbon dioxide is dissolved in a beaker filled with an electrolyte liquid and a small amount of the liquid metal, which is then charged with an electrical current.

The CO2 slowly converts into solid flakes of carbon, which are naturally detached from the liquid metal surface, allowing the continuous production of carbonaceous solid.

Esrafilzadeh said the carbon produced could also be used as an electrode.

"A side benefit of the process is that the carbon can hold electrical charge, becoming a supercapacitor, so it could potentially be used as a component in future vehicles."

"The process also produces synthetic fuel as a by-product, which could also have industrial applications."

The research was conducted at RMIT's MicroNano Research Facility and the RMIT Microscopy and Microanalysis Facility, with lead investigator, Honorary RMIT and ARC Laureate Fellow, Professor Kourosh Kalantar-Zadeh (now UNSW).

The research is supported by the Australian Research Council Centre for Future Low-Energy Electronics Technologies (FLEET) and the ARC Centre of Excellence for Electromaterials Science (ACES).

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Tweets tell scientists how quickly we normalize unusual weather

Geocolor image from NOAA's GOES-16 satellite of powerful East Coast storm on Jan. 4, 2018.

What kinds of weather do people find remarkable, when does that change, and what does that say about the public's perception of climate change? A study led by the University of California, Davis, examined those questions through the lens of more than 2 billion U.S. Twitter posts.

The study, published Feb. 25 in the journal Proceedings of the National Academy of Sciences, indicates that people have short memories when it comes to what they consider "normal" weather. On average, people base their idea of normal weather on what has happened in just the past two to eight years. This disconnect with the historical climate record may obscure the public's perception of climate change.

"There's a risk that we'll quickly normalize conditions we don't want to normalize," said lead author Frances C. Moore, an assistant professor in the UC Davis Department of Environmental Science and Policy. "We are experiencing conditions that are historically extreme, but they might not feel particularly unusual if we tend to forget what happened more than about five years ago."

TRENDING ON TWITTER

To reach their conclusions, the researchers quantified a timeless and universal pastime -- talking about the weather -- by analyzing posts on Twitter.

They sampled 2.18 billion geolocated tweets created between March 2014 and November 2016 to determine what kind of temperatures generated the most posts about weather. They found that people often tweet when temperatures are unusual for a particular place and time of year -- a particularly warm March or unexpectedly freezing winter, for example.

However, if the same weather persisted year after year, it generated less comment on Twitter, indicating that people began to view it as normal in a relatively short amount of time.

THE BOILING FROG

This phenomenon, note the authors, is a classic case of the boiling-frog metaphor: A frog jumps into a pot of boiling hot water and immediately hops out. If, instead, the frog in the pot is slowly warmed to a boiling temperature, it doesn't hop out and is eventually cooked. While scientifically inaccurate, this metaphor has long been used as a cautionary tale warning against normalizing the steadily changing conditions caused by climate change.

Sentiment analysis tools, which measure the positive or negative association of words, provided evidence for this "boiling-frog effect." After repeat exposures to historically-extreme temperatures, people tweeted less about the weather specifically, but they still expressed negative sentiments overall. Particularly cold or hot conditions still seemed to make people unhappy and grumpy.

"We saw that extreme temperatures still make people miserable, but they stop talking about it," Moore said. "This is a true boiling-frog effect. People seem to be getting used to changes they'd prefer to avoid. But just because they're not talking about it doesn't mean it's not making them worse off."

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Continued sea-level rise on East and Gulf coasts detailed

This is a screenshot of the 2050 projection of sea level in Norfolk, Virginia. VIMS' Sea-Level Report Cards provide similar interactive projections for 32 US coastal localities from Maine to Alaska. Credit Virginia Institute of Marine Science This is a screenshot of the 2050 projection of sea level in Norfolk, Virginia. VIMS' Sea-Level Report Cards provide similar interactive projections for 32 US coastal localities from Maine to Alaska.

Researchers at William & Mary's Virginia Institute of Marine Science have issued the first annual update of their sea level "report cards," marking 50 years of water-level observations from 1969 through 2018.

These web-based charts -- available online at https://www.vims.edu/research/products/slrc/index.php -- project sea level out to the year 2050 based on an ongoing analysis of tide-gauge records for 32 localities along the U.S. coastline from Maine to Alaska. Release of this year's cards was delayed by the 35-day government shutdown, which precluded compilation of and access to NOAA's latest tide-gauge records.

The lead on the project, VIMS emeritus professor John Boon, says the report cards add value by providing sea-level projections that are updated more frequently than those issued by NOAA or other agencies.

Boon and colleagues also use a statistical approach that includes evidence for recent acceleration in the rate of sea-level change at many U.S. tide-gauge stations, and stress their use of relative sea-level measurements -- changes in water level relative to the land surface on which people live and work. The relative sea-level rise in Virginia and other East and Gulf coast areas is due to both rising water and sinking land.

This year's report cards, updated using monthly summaries of daily tide gauge records from calendar year 2018, show that trends in sea-level change generally held steady across the 32 stations, although the processes that control sea level fluctuated slightly from region to region.

Molly Mitchell, the VIMS marine scientist who compiled and analyzed this year's tide-gauge data, highlights two features of the sea-level report cards for 2018.

First is the clear signal of September's Hurricane Florence as captured in the tide-gauge record for Wilmington, North Carolina. "Heavy rainfall in North Carolina contributed to high water levels at Wilmington throughout the fall," says Mitchell, "although this had only a minor impact on the long-term trend since it was a temporary increase." Florence dropped from 20 to more than 30 inches of rain across most of coastal North Carolina between September 14th and 18th.

Mitchell also notes a noticeable acceleration in sea-level rise at five of the eight monitored locations along the California, Oregon, and Washington coasts. "Although sea level has been rising very slowly along the West Coast, models have been predicting that it will start to rise faster," she says. "The report cards from the past two years support this idea." Scientists suggest that the speed-up is due to a shift in wind patterns associated with the Pacific Decadal Oscillation, an El Niño-like pattern of climate variability.

Sea level along the Gulf Coast at Grand Isle, Louisiana and Galveston, Texas continued to rise at high rates in 2018 (7.75 millimeters per year at Grand Isle and 6.19 mm/year at Galveston), while showing no sign of significant acceleration at either location. Should the lack of acceleration continue, projected sea level through 2050 for these locations will roughly equal that for Norfolk, Virginia (about 0.49 meters [1.6 feet] above 1992 levels), even though their rise rates are presently much greater -- first and third highest of the 32 monitored locations.

A high rise rate (6.72 mm/year) is also found at Rockport, Texas south of Galveston but here the measured acceleration through 2018 is the highest of any location at 0.240 mm/year2, making its year 2050 projection correspondingly high at 0.78 meter (2.6 feet) above 1992 levels. Mitchell and Boon attribute the locally high rise rates and sharp contrast in acceleration among these Gulf Coast stations to their location within a sedimentary basin with a complex history of water and hydrocarbon extraction. Pumping of groundwater and oil can cause land subsidence, which contributes to relative sea-level rise.

The value of an annual, localized report card

Because long-term changes in sea level are typically on the order of a few millimeters per year, researchers have traditionally felt little need to issue frequent forecasts of sea-level changes. Moreover, many sea-level projections are global in scope, with a forecast horizon of 2100 -- far enough off to allow for readily discernible linear change. Thus the United Nation's oft-reported projection of 44 to 74 centimeters (1.4 to 2.4 feet) of absolute sea-level rise by the end of the century.

The VIMS team has purposefully taken a more localized and timely approach, one designed to add maximum value for coastal residents, businesses, and governments.

Says Boon, "Our report cards show what sea level has been doing recently, what's happening now at your locality. Numerous studies show that local rates of sea-level rise and acceleration differ substantially from the global rates published by the IPCC and NOAA -- a key result because local rates of relative sea-level rise give a direct indication of the extent to which homes, buildings, and roads are at risk of flooding."

The team's decision to use a subset of available tide-gauge data runs counter to the traditional approach taken by NOAA, the agency that operates the nation's official network of tidal stations. "NOAA should be commended for their care in ensuring the continuity, consistency, and availability of the nation's long-term tidal datasets," says Boon. "But at the same time, a longer record isn't always better, especially when there's evidence of recent non-linear changes in the rate of sea-level rise like we see along the U.S. East Coast."

An earlier analysis by Boon showed that this acceleration began in 1987, at the center of a 36-year sliding window beginning in 1969 -- thus setting the start date for the VIMS report cards. This is decades after many U.S. tide-gauge stations began operation but within a span where many more stations now have complete or nearly complete records. Given recent evidence of ongoing warming, it makes sense in a nation-wide, comparative study of sea-level change to analyze only those observations made over the same period of time.

Mitchell explains further, "If you cross a threshold in terms of something like sea-level rise, what came before -- say a tide-gauge record that began in 1900 -- is biased in terms of seeing where you're going. We think the ice sheets are melting faster today than they ever have, and if that's true then the previous 90 years of data won't accurately predict the future."

The difference between the linear rates used in NOAA's sea-level forecasts and the non-linear, accelerating rates used in VIMS' report cards can lead to sharply different forecasts of our sea-level future. Extending NOAA's linear sea-level projections to mid-century for the tide gauge in Norfolk, Virginia indicates that sea level here will be 0.3 meters (11.8 inches) higher by 2050, while the VIMS forecast -- using a non-linear, accelerating rate -- is 0.49 meters, or 19.3 inches. That extra 20 centimeters (8 inches) of sea-level rise would have major implications for the low-lying region.

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ALMA differentiates two birth cries from a single star

The protostar is located at the center and the gas streams are ejected to the east and west (left and right). The slow outflow is shown in orange and the fast jet is shown in blue. It is obvious that the axes of the outflow and jet are misaligned.

Astronomers have unveiled the enigmatic origins of two different gas streams from a baby star. Using ALMA, they found that the slow outflow and the high speed jet from a protostar have misaligned axes and that the former started to be ejected earlier than the latter. The origins of these two flows have been a mystery, but these observations provide telltale signs that these two streams were launched from different parts of the disk around the protostar.

Stars in the Universe have a wide range of masses, ranging from hundreds of times the mass of the Sun to less than a tenth of that of the Sun. To understand the origin of this variety, astronomers study the formation process of the stars, that is the aggregation of cosmic gas and dust.

Baby stars collect the gas with their gravitational pull, however, some of the material is ejected by the protostars. This ejected material forms a stellar birth cry which provides clues to understand the process of mass accumulation.

Yuko Matsushita, a graduate student at Kyushu University and her team used ALMA to observe the detailed structure of the birth cry from the baby star MMS5/OMC-3 and found two different gaseous flows: a slow outflow and a fast jet. There have been a handful of examples with two flows seen in radio waves, but MMS5/OMC-3 is exceptional.

"Measuring the Doppler shift of the radio waves, we can estimate the speed and lifetime of the gas flows," said Matsushita, the lead author of the research paper that appeared in the Astrophysical Journal. "We found that the jet and outflow were launched 500 years and 1300 years ago, respectively. These gas streams are quite young."

More interestingly, the team found that the axes of the two flows are misaligned by 17 degrees. The axis of the flows can be changed over long time periods due to the precession of the central star. But in this case, considering the extreme youth of the gas streams, researchers concluded that the misalignment is not due to precession but is related to the launching process.

There are two competing models for the formation mechanism of the protostellar outflows and jets. Some researchers assume that the two streams are formed independently in different parts of the gas disk around the central baby star, while others propose that the collocated jet is formed first, then it entrains the surrounding material to form the slower outflows. Despite extensive research, astronomers had not yet reached a conclusive answer.

A misalignment in the two flows could occur in the 'independent model,' but is difficult in the 'entrainment model.' Moreover, the team found that the outflow was ejected considerably earlier than the jet. This clearly backs the 'independent model.'

"The observation well matches the result of my simulation," said Masahiro Machida, a professor at Kyushu University. A decade ago, he performed pioneering simulation studies using a supercomputer operated by the National Astronomical Observatory of Japan. In the simulation, the wide-angle outflow is ejected from the outer area of the gaseous disk around a prototar, while the collimated jet is launched independently from the inner area of the disk. Machida continues, "An observed misalignment between the two gas streams may indicate that the disk around the protostar is warped."

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Neanderthals walked upright just like the humans of today

Virtual reconstruction of the skeleton found in La Chapelle-aux-Saints, based on high-resolution 3D surface scans of the spine and pelvis.

Neanderthals are often depicted as having straight spines and poor posture. However, these prehistoric humans were more similar to us than many assume. University of Zurich researchers have shown that Neanderthals walked upright just like modern humans -- thanks to a virtual reconstruction of the pelvis and spine of a very well-preserved Neanderthal skeleton found in France.

An upright, well-balanced posture is one of the defining features of Homo sapiens. In contrast, the first reconstructions of Neanderthals made in the early 20th century depicted them as only walking partially upright. These reconstructions were based on the largely preserved skeleton of an elderly male Neanderthal unearthed in La Chapelle-aux-Saints, France.

Changing perspectives

Since the 1950s, scientists have known that the image of the Neanderthal as a hunched over caveman is not an accurate one. Their similarities to ourselves -- both in evolutionary and behavioral terms -- have also long been known, but in recent years the pendulum has swung in the opposite direction. "Focusing on the differences is back in fashion," says Martin Haeusler, UZH specialist in evolutionary medicine. For instance, recent studies have used a few isolated vertebrae to conclude that Neanderthals did not yet possess a well-developed double S-shaped spine.

However, a virtual reconstruction of the skeleton from La Chapelle-aux-Saints has now delivered evidence to the contrary. This computer-generated anatomical model was created by the research group led by Martin Haeusler from the University of Zurich and included Erik Trinkaus from Washington University in St. Louis. The researchers were able to show that both the individual in question as well as Neanderthals in general had a curved lumbar region and neck -- just like the humans of today.

Sacrum, vertebrae and signs of wear as evidence

When reconstructing the pelvis, the researchers discovered that the sacrum was positioned in the same way as in modern humans. This led them to conclude that Neanderthals possessed a lumbar region with a well-developed curvature. By putting together the individual lumbar and cervical vertebrae, they were able to discern that the spinal curvature was even more pronounced. The very close contact between the spinous processes -- the bony projections off the back of each vertebra -- became clear, as did the prominent wear marks that were in part caused by the curvature of the spine.

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Ancient rocks provide clues to Earth's early history

The 2.5 billion-year-old Mt. McRae Shale from Western Australia was analyzed for thallium and molybdenum isotope compositions, revealing a pattern that indicates manganese oxide minerals were being buried over large regions of the ancient sea floor. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago.

Oxygen in the form of the oxygen molecule (O2), produced by plants and vital for animals, is thankfully abundant in Earth's atmosphere and oceans. Researchers studying the history of O2 on Earth, however, know that it was relatively scarce for much of our planet's 4.6 billion-year existence.

So when and where did O2 begin to build up on Earth?

By studying ancient rocks, researchers have determined that sometime between 2.5 and 2.3 billion years ago, Earth underwent what scientists call the "Great Oxidation Event" or "GOE" for short. O2 first accumulated in Earth's atmosphere at this time and has been present ever since.

Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth's ancient shallow oceans before the GOE. And in a study published recently in the journal Nature Geoscience, a research team led by scientists at Arizona State University (ASU) has provided compelling evidence for significant ocean oxygenation before the GOE, on a larger scale and to greater depths than previously recognized.

For this study, the team targeted a set of 2.5 billion-year-old marine sedimentary rocks from Western Australia known as the Mt. McRae Shale. "These rocks were perfect for our study because they were shown previously to have been deposited during an anomalous oxygenation episode before the Great Oxidation Event," says lead author Chadlin Ostrander of ASU's School of Earth and Space Exploration.

Shales are sedimentary rocks that were, at some time in Earth's past, deposited on the sea floor of ancient oceans. In some cases, these shales contain the chemical fingerprints of the ancient oceans they were deposited in.

For this research, Ostrander dissolved shale samples and separated elements of interest in a clean lab, then measured isotopic compositions on a mass spectrometer. This process was completed with the help of co-authors Sune Nielsen at Woods Hole Oceanographic Institution (Massachusetts); Jeremy Owens at Florida State University; Brian Kendall at the University of Waterloo (Ontario, Canada); scientists Gwyneth Gordon and Stephen Romaniello of ASU's School of Earth and Space Exploration; and Ariel Anbar of ASU's School of Earth and Space Exploration and School of Molecular Sciences. Data collection took over a year and utilized facilities at Woods Hole Oceanographic Institution, Florida State University, and ASU.

Using mass spectrometers, the team measured the thallium and molybdenum isotope compositions of the Mt. McRae Shale. This was the first time both isotope systems had been measured in the same set of shale samples. As hypothesized, a predictable thallium and molybdenum isotope pattern emerged, indicating that manganese oxide minerals were being buried in the sea floor over large regions of the ancient ocean. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago.

These findings improve scientists' understanding of Earth's ocean oxygenation history. Accumulation of O2 was probably not restricted to small portions of the surface ocean prior to the GOE. More likely, O2 accumulation extended over large regions of the ocean and extended far into the ocean's depths. In some of these areas, O2 accumulation seems to have even extended all the way down to the sea floor.

"Our discovery forces us to re-think the initial oxygenation of Earth," states Ostrander. "Many lines of evidence suggest that O2 started to accumulate in Earth's atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth's initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth's oceans -- to significant levels, according to our data -- well before doing so in the atmosphere."

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New chimpanzee culture discovered

Chimpanzee tool types in Northern DR Congo. From left to right: tool for the extraction of Epigaeic Dorylus ants, honey (ground), honey (tree), Ponerine ants, Dorylus kohli ants; South Uele tools.

Chimpanzees have a more elaborate and diversified material culture than any other nonhuman primate. Their behavior varies across tropical Africa in a way that does not always correspond to ecology: for instance, only West African chimpanzees, but no others, use stone and wooden hammers to crack nuts in a number of populations, despite the wide availability of hammers and appropriate nuts across the species' range. An understanding of the extent of this behavioral diversity is crucial to help researchers understand the likely incipient traditions of our own earliest hominin ancestors.

Previously, several large-scale behavioral patterns in chimpanzees have been documented, including the use of clubs to pound open beehives in Central Africa and long tools to scoop up algae across multiple sites in West Africa. A team of researchers from the MPI-EVA and the University of Warsaw now present a detailed description of a new 'behavioral realm' in Eastern chimpanzees (Pan troglodytes schweinfurthii) of the Bili-Uéré region, Northern DR Congo. This set of behaviors covers a minimum of 50,000 km² and possibly extends across an even larger area. "Over a 12-year period, we documented chimpanzee tools and artefacts at 20 survey areas and gathered data on dung, feeding remains, and sleeping nests," says lead author Thurston C. Hicks, guest researcher at the MPI-EVA and associate professor at the Faculty of 'Artes Liberales', The University of Warsaw. "We describe a new chimpanzee tool kit: long probes used to harvest epigaeic driver ants (Dorylus spp.), short probes used to extract ponerine ants and the arboreal nests of stingless bees, thin wands to dip for D. kohli, and stout digging sticks used to access underground meliponine nests."

In addition, the researchers document an expanded percussive technology associated with food processing: in addition to pounding hard-shelled fruits against substrates (which is seen in other chimpanzee populations), the Bili-Uéré apes also pound open two kinds of termite mounds, Cubitermes sp. and Thoracotermes macrothorax, a resource that chimpanzees in most other regions ignore. These chimpanzees, on the other hand, appear not to exploit the common termite Macrotermes muelleri, for which chimpanzees fish at a number of other long-term research sites. "We have also documented tentative evidence of the pounding of African giant snails and tortoises against substrates, both novel food resources for chimpanzees. Finally, ground-nesting behavior is common across the area," adds Hicks.

Despite an overall similarity of behaviors across two sides of a major river (the Uele) and in two very different habitat types (savannah-tropical forest mosaic to the north and tropical moist forest to the south), the research team encountered some geographic variation in the chimpanzees' behaviour, including differing encounter rates for epigaeic driver ant tools, a lack of honey-digging tools to the south; and long driver ant probes and fruit-pounding sites only to the north of the Uele River.

"Nowadays we may feel like we have already discovered all there is to discover. What a nice surprise, then, to find a new chimpanzee behavioral realm! This just goes to show that not everything has yet been mapped out, and we have so much more to learn about the natural world," says co-author Hjalmar Kühl, an ecologist at the MPI-EVA and the research center iDiv.

"In today's overdeveloped world, opportunities such as this, to study a large intact nonhuman great ape culture interconnected across tens of thousands of kilometres of forest, are vanishingly rare," says Hicks. "We need such natural laboratories in order to understand the way in which material culture spreads among healthy, thriving populations of hominids. Without this, it may be difficult to envisage the innovations made by our own ancestors in the woodlands of Africa millions of years ago."

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