New study puts a definitive age on Saturn’s rings—they’re really young

Peer-Reviewed Publication

UNIVERSITY OF COLORADO AT BOULDER

A new study led by physicist Sascha Kempf at the University of Colorado Boulder has delivered the strongest evidence yet that Saturn’s rings are remarkably young—potentially answering a question that has boggled scientists for well over a century. 

The research, to be published May 12 in the journal Science Advances, pegs the age of Saturn’s rings at no more than 400 million years old. That makes the rings much younger than Saturn itself, which is about 4.5 billion years old.

“In a way, we’ve gotten closure on a question that started with James Clerk Maxwell,” said Kempf, associate professor in the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder.

The researchers arrived at that closure by studying what might seem like an unusual subject: dust. 

Kempf explained that tiny grains of rocky material wash through Earth’s solar system on an almost constant basis. In some cases, this flux can leave behind a thin layer of dust on planetary bodies, including on the ice that makes up Saturn’s rings.

In the new study, he and his colleagues set out to put a date on Saturn’s rings by studying how rapidly this layer of dust builds up—a bit like telling how old a house is by running your finger along its surfaces.

“Think about the rings like the carpet in your house,” Kempf said. “If you have a clean carpet laid out, you just have to wait. Dust will settle on your carpet. The same is true for the rings.”

It was an arduous process: From 2004 to 2017, the team used an instrument called the Cosmic Dust Analyzer aboard NASA’s late Cassini spacecraft to analyze specks of dust flying around Saturn. Over those 13 years, the researchers collected just 163 grains that had originated from beyond the planet’s close neighborhood. But it was enough. Based on their calculations, Saturn’s rings have likely been gathering dust for only a few hundred million years.

The planet’s rings, in other words, are new phenomena, arising (and potentially even disappearing) in what amounts to a blink of an eye in cosmic terms. 

“We know approximately how old the rings are, but it doesn’t solve any of our other problems,” Kempf said. “We still don’t know how these rings formed in the first place.”

From Galileo to Cassini

Researchers have been captivated by these seemingly-translucent rings for more than 400 years. In 1610, Italian astronomer Galileo Galilei first observed the features through a telescope, although he didn’t know what they were. (Galileo’s original drawings make the rings look a bit like the handles on a water jug). In the 1800s, Maxwell, a scientist from Scotland, concluded that Saturn’s rings couldn’t be solid but were, instead, made up of many individual pieces. 

Today, scientists know that Saturn hosts seven rings comprised of countless chunks of ice, most no bigger than a boulder on Earth. Altogether, this ice weighs about half as much as Saturn’s moon Mimas and stretches nearly 175,000 miles from the planet’s surface. 

Kempf added that for most of the 20th Century, scientists assumed that the rings likely formed at the same time as Saturn. 

But that idea raised a few issues—namely, Saturn’s rings are sparkling clean. Observations suggest that these features are made up of roughly 98% pure water ice by volume, with only a tiny amount of rocky matter. 

“It’s almost impossible to end up with something so clean,” Kempf said.

Cassini offered an opportunity to put a definitive age on Saturn’s rings. The spacecraft first arrived at Saturn in 2004 and collected data until it purposefully crashed into the planet's atmosphere in 2017. The Cosmic Dust Analyzer, which was shaped a bit like a bucket, scooped up small particles as they whizzed by. 

Engineers and scientists at LASP designed and built a much more sophisticated dust analyzer for NASA’s upcoming Europa Clipper mission, which is scheduled to launch in 2024.

The team estimated that this interplanetary grime would contribute far less than a gram of dust to each square foot of Saturn’s rings every year—a light sprinkle, but enough to add up over time. Previous studies had also suggested that the rings could be young but didn’t include definitive measures of dust accumulation.

Stroke of luck

The rings might already be vanishing. In a previous study, NASA scientists reported that the ice is slowly raining down onto the planet and could disappear entirely in another 100 million years.

That these ephemeral features existed at a time when Galileo and the Cassini spacecraft could observe them seems almost too good to be true, Kempf said—and it begs an explanation for how the rings formed in the first place. Some scientists, for example, have posited that Saturn’s rings may have formed when the planet’s gravity tore apart one of its moons.

 “If the rings are short lived and dynamical, why are we seeing them now?” he said. “It’s too much luck.”

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Co-authors on the new study include Nicolas Altobelli of the European Space Agency; Jürgen Schmidt of the Freie Universität Berlin; Jeffrey Cuzzi and Paul Estrada of the NASA Ames Research Center; and Ralf Srama of the Universität Stuttgart.

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JOURNAL

Science Advances

DOI

10.1126/sciadv.adf8537 

ARTICLE TITLE

Micrometeoroid infall onto Saturn’s rings constrains their age to no more than a few hundred million years

ARTICLE PUBLICATION DATE

12-May-2023

Disclaimer: AAAS an

Celestial monsters at the origin of globular clusters

A team from the universities of Geneva, Paris and Barcelona has found strong evidence that supermassive stars can explain the anomalies observed in large clusters of stars.

Peer-Reviewed Publication

UNIVERSITÉ DE GENÈVE

Globular clusters are the most massive and oldest star clusters in the Universe. They can contain up to 1 million of them. The chemical composition of these stars, born at the same time, shows anomalies that are not found in any other population of stars. Explaining this specificity is one of the great challenges of astronomy. After having imagined that supermassive stars could be at the origin, a team from the Universities of Geneva and Barcelona, and the Institut d’Astrophysique de Paris (CNRS and Sorbonne University) believes it has discovered the first chemical trace attesting to their presence in globular proto-clusters, born about 440 million years after the Big Bang. These results, obtained thanks to observations by the James-Webb space telescope, are to be found in Astronomy and Astrophysics.

Globular clusters are very dense groupings of stars distributed in a sphere, with a radius varying from a dozen to a hundred light years. They can contain up to 1 million stars and are found in all types of galaxies. Ours is home to about 180 of them. One of their great mysteries is the composition of their stars: why is it so varied? For instance, the proportion of oxygen, nitrogen, sodium and aluminium varies from one star to another. However, they were all born at the same time, within the same cloud of gas. Astrophysicists speak of ‘‘abundance anomalies’’.

Monsters with very short lives

A team from the universities of Geneva (UNIGE) and Barcelona, and the Institut d’Astrophysique de Paris (CNRS and Sorbonne University) has made a new advance in the explanation of this phenomenon. In 2018, it had developed a theoretical model according to which supermassive stars would have «polluted» the original gas cloud during the formation of these clusters, enriching their stars with chemical elements in a heterogeneous manner. ‘‘Today, thanks to the data collected by the James-Webb Space Telescope, we believe we have found a first clue of the presence of these extraordinary stars,’’ explains Corinne Charbonnel, a full professor in the Department of Astronomy at the UNIGE Faculty of Science, and first author of the study.

These celestial monsters are 5 000 to 10 000 times more massive and five times hotter at their centre (75 million °C) than the Sun. But proving their existence is complex. ‘‘Globular clusters are between 10 and 13 billion years old, whereas the maximum lifespan of superstars is two million years. They therefore disappeared very early from the clusters that are currently observable. Only indirect traces remain,’’ explains Mark Gieles, ICREA professor at the University of Barcelona and co-author of the study.

Revealed by light

Thanks to the very powerful infrared vision of the James-Webb telescope, the co-authors were able to support their hypothesis. The satellite captured the light emitted by one of the most distant and youngest galaxies known to date in our Universe. Located at about 13.3 billion light-years, GN-z11 is only a few tens of millions of years old. In astronomy, the analysis of the light spectrum of cosmic objects is a key element in determining their characteristics. Here, the light emitted by this galaxy has provided two valuable pieces of information.

‘‘It has been established that it contains very high proportions of nitrogen and a very high density of stars,’’ says Daniel Schaerer, associate professor in the Department of Astronomy at the UNIGE Faculty of Science, and co-author of the study. This suggests that several globular clusters are forming in this galaxy and that they still harbour an active supermassive star. ‘‘The strong presence of nitrogen can only be explained by the combustion of hydrogen at extremely high temperatures, which only the core of supermassive stars can reach, as shown by the models of Laura Ramirez-Galeano, a Master’s student in our team,’’ explains Corinne Charbonnel.

These new results strengthen the international team’s model. The only one currently capable of explaining the abundance anomalies in globular clusters. The next step for the scientists will be to test the validity of this model on other globular clusters forming in distant galaxies, using the James-Webb data.

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JOURNAL

Astronomy and Astrophysics

DOI

10.1051/0004-6361/202346410 

METHOD OF RESEARCH

News article

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

N-enhancement in GN-z11: First evidence for supermassive stars nucleosynthesis in proto-globular clusters-like conditions at high redshift?

Tidal shocks can light up the remains of a star being pulled apart by a black hole

Peer-Reviewed Publication

UNIVERSITY OF TURKU

 

IMAGE: IN A TIDAL DISRUPTION EVENT, A STAR MOVES CLOSE ENOUGH TO A SUPERMASSIVE BLACK HOLE SO THAT THE GRAVITATIONAL PULL OF THE BLACK HOLE BENDS THE STAR UNTIL IT IS DESTROYED (IMAGE 1). THE STELLAR MATTER FROM THE DESTROYED STAR FORMS AN ELLIPTICAL STREAM AROUND THE BLACK HOLE (IMAGE 2). TIDAL SHOCKS ARE FORMED AROUND THE BLACK HOLE AS THE GAS HITS ITSELF ON ITS WAY BACK AFTER CIRCLING THE BLACK HOLE (IMAGE 3). THE TIDAL SHOCKS CREATE BRIGHT OUTBURSTS OF POLARISED LIGHT THAT CAN BE OBSERVED IN OPTICAL AND ULTRAVIOLET WAVELENGTHS. OVER TIME, THE GAS FROM THE DESTROYED STAR FORMS AN ACCRETION DISK AROUND THE BLACK HOLE (IMAGE 4) FROM WHERE IT IS SLOWLY PULLED INTO THE BLACK HOLE. THE SCALE OF THE IMAGE IS NOT ACCURATE. view more 

CREDIT: JENNI JORMANAINEN

The Universe is a violent place where even the life of a star can be cut short. This occurs when a star finds itself in a "bad" neighbourhood, specifically near a supermassive black hole.

These black holes weigh millions or even billions of times the mass of the Sun and typically reside in the centres of quiet galaxies. As a star moves closer to the black hole, it experiences the ever-increasing gravitational pull of the supermassive black hole until it becomes more powerful than the forces that keep the star together. This results in the star being disrupted or destroyed, an event known as a Tidal Disruption Event (TDE).

“After the star has been ripped apart, its gas forms an accretion disk around the black hole. The bright outbursts from the disk can be observed in nearly every wavelength, especially with optical telescopes and satellites that detect X-rays,” says Postdoctoral Researcher Yannis Liodakis from the University of Turku and the Finnish Centre for Astronomy with ESO (FINCA).

Until recently, researchers knew only of a few TDEs, as there were not many experiments capable of detecting them. In recent years, however, scientists have developed the necessary tools to observe more TDEs.  Interestingly, but perhaps not too surprisingly, these observations have led to new mysteries that the researchers are currently studying.

“Observations from large-scale experiments with optical telescopes have revealed that a large number of TDEs do not produce X-rays even though the bursts of visible light can be clearly detected. This discovery contradicts our basic understanding of the evolution of the disrupted stellar matter in TDEs,” Liodakis notes.

A study published in the journal Science by an international team of astronomers led by the Finnish Centre for Astronomy with ESO suggests that the polarised light coming from TDEs might hold the key to solving this mystery.

Instead of the formation of an X-ray bright accretion disk around the black hole, the observed outburst in the optical and ultraviolet light detected in many TDEs can arise from tidal shocks. These shocks form far away from the black hole as the gas from the destroyed star hits itself on its way back after circling the black hole. The X-ray bright accretion disk would form much later in these events. 

"Polarisation of light can provide unique information about the underlying processes in astrophysical systems. The polarised light we measured from the TDE could only be explained by these tidal shocks,” says Liodakis, who is the lead author of the study.

Polarised light helped researchers to understand the destruction of stars

The team received a public alert in late 2020 from the Gaia satellite of a nuclear transient event in a nearby galaxy designated as AT 2020mot. The researchers then observed AT 2020mot in a wide range of wavelengths including optical polarisation and spectroscopy observations conducted at the Nordic Optical Telescope (NOT), which is owned by the University of Turku. The observations conducted at the NOT were particularly instrumental in making this discovery possible. In addition, the polarisation observations were done as part of the observational astronomy course for high school students.

"The Nordic Optical Telescope and the polarimeter we use in the study have been instrumental in our efforts to understand supermassive black holes and their environments," says Doctoral Researcher Jenni Jormanainen from FINCA and the University of Turku who led the polarisation observations and analysis with the NOT.

The researchers found that the optical light coming from AT 2020mot was highly polarised and was varying with time. Despite several attempts, none of the radio or X-ray telescopes were able to detect radiation from the event before, during, or even months after the peak of the outburst.

“When we saw how polarised AT2020mot was, we immediately thought of a jet shooting out from the black hole, as we often observe around supermassive black holes that accrete the surrounding gas. However, no jet was there to be found,” says Elina Lindfors, an Academy Research Fellow at the University of Turku and FINCA.

The team of astronomers realised that the data most closely matched a scenario where the stream of stellar gas collides with itself and forms shocks near the pericenter and apocenter of its orbit around the black hole. The shocks then amplify and order the magnetic field in the stellar stream which will naturally lead to highly polarised light. The level of the optical polarisation was too high to be explained by most models, and the fact that it was changing over time made it even harder.

“All models we looked at could not explain the observations, except the tidal shock model,” notes Karri Koljonen, who was an astronomer at FINCA at the time of the observations and is now working at the Norwegian University of Science and Technology (NTNU).

The researchers will continue to observe the polarised light coming from TDEs and may soon discover more about what happens after a star is disrupted.

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JOURNAL

Science

DOI

10.1126/science.abj9570 

ARTICLE TITLE

Optical polarization from colliding stellar stream shocks in a tidal disruption event

ARTICLE PUBLICATION DATE

11-May-2023

SARS-CoV-2 seasonal behavior traced back to genetics and global change

Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

 

IMAGE: GUSTAVO CAETANO-ANOLLÉS (PICTURED) AND HIS UNIVERSITY OF ILLINOIS RESEARCH TEAM PROVIDE NEW EVIDENCE OF SARS-COV-2 SEASONALITY IN TWO PAPERS, INCLUDING ONE CORRELATING SEASONAL VIRAL BEHAVIOR WITH METRICS OF ENVIRONMENTAL HEALTH AND ANOTHER ANALYZING 12 MILLION VIRAL GENOMES OVER TWO YEARS OF THE PANDEMIC. THE DISCOVERIES COULD GUIDE POLICY, PUBLIC HEALTH, AND PHARMACEUTICAL INTERVENTIONS. PHOTO CREDIT L. BRIAN STAUFFER, UNIVERSITY OF ILLINOIS. view more 

CREDIT: L. BRIAN STAUFFER, UNIVERSITY OF ILLINOIS.

URBANA, Ill. — As the northern hemisphere heads into summer, we may be in for a COVID-19 reprieve. Not because the pandemic is over; the Omicron subvariant ‘Arcturus’ is still creeping upward and causing new symptoms. But two new studies from the University of Illinois add evidence supporting a seasonal pattern in the behavior of the SARS-CoV-2 virus. 

The first study, published in Evolutionary Bioinformatics, correlates two years of pandemic data (COVID cases and deaths) with average annual temperature and latitude in 171 countries across the globe. The researchers also evaluated relationships between COVID and environmental health, including indicators of global change. 

“We found correlations were significant and maintained as the pandemic progressed, regardless of vaccines or the appearance of new viral variants. Results provide strong evidence that the virus is seasonal,” said study author Gustavo Caetano-Anollés, professor in the Department of Crop Sciences, part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at U of I. Caetano-Anollés is also an affiliate of the Carl R. Woese Institute for Genomic Biology. “Remarkably, the seasonal effects we uncovered were not obscured by the wide range of elimination and mitigation policies applied throughout the world.”

Caetano-Anollés and co-author Nicolas Hernandez showed that correlations between COVID-19 metrics (new cases and deaths, total cases and deaths) and temperature and latitude strengthened during cooler months and at higher latitudes. 

“We found that countries with colder average temperatures were generally correlated with higher incidence and mortality rates across the pandemic. This pattern suggests that future seasonal changes could lead to more predictable trends in COVID-19 cases and deaths,” said Hernandez, an undergraduate researcher studying in the Department of Animal Sciences in the College of ACES.

The team also evaluated relationships between COVID-19 metrics and environmental health indicators using Yale’s Environmental Performance Index (EPI) and the State of Global Air report. These databases include scores relating to climate change, pollution emissions, household air pollution, and similar metrics for more than 150 countries globally. 

When the team analyzed patterns for March 2021, they found total COVID-19 cases and deaths were correlated with countries' overall proactiveness to reduce pollutant emissions, such as carbon dioxide, sulfur dioxide, and nitrogen oxides. The analysis also showed higher particulate matter levels and household use of solid fuels were strongly correlated with COVID-19 cases and deaths.

“To improve public health, responsible environmental policies must be established at the country level. These policies should aim to reduce the impact of biotic and environmental stressors,” Caetano-Anollés said. “Harming the environment harms public health as a whole.”

In a second paper, published in F1000Research, Caetano-Anollés teamed up with doctoral student Tre Tomaszewski in the School of Information Sciences at U of I to analyze sequences of more than 12 million SARS-CoV-2 genomes between the start of the pandemic and late July 2022. They watched in a time-series analysis as more than 180,000 mutations appeared, coalesced, persisted, and/or died away across three major variants of concern (VOCs), Alpha, Delta, and Omicron. 

The research team tracked the progression across climate zones, finding a marked difference in the uptake of certain groups of presumably advantageous mutations across regions. For example, several haplotypes–gene variations inherited together–weren’t as prominent in the tropics as they were in the northern temperate zone, especially early in the pandemic. 

“We found many haplotypes were decoupled by latitude, suggesting seasonal behavior of SARS-CoV-2 is genetically encoded,” Tomaszewski said. “Consequently, seasonal effects could be potentially manipulated through vaccine design.”

Both studies build on earlier work by Caetano-Anollés’ team showing strong latitude-dependent trends in viral evolution. They found latitude-linked patterns in a global analysis of viral genomes early in the pandemic and again in Australia, more recently. They also identified a molecular temperature sensor on the virus, limiting infectivity in hot, humid conditions. Along with the new analyses, the researchers say it all points to seasonality of SARS Co-V 2, regardless of the variant. 

“Worldwide correlations support COVID-19 seasonal behavior and impact of global change” is published in Evolutionary Bioinformatics [DOI: 10.1177/11769343231169377]. Authors include Nicolas Hernandez and Gustavo Caetano-Anollés. The research was supported by the College of ACES and the National Center for Supercomputing Applications at the University of Illinois. 

“Seasonal effects decouple SARS-CoV-2 haplotypes worldwide” is published in F1000Research [DOI: 10.12688/f1000research.131522.1]. Authors include Tre Tomaszewski, Muhammad Asif Ali, Kelsey Caetano-Anollés, and Gustavo Caetano-Anollés. The research was supported by the National Institute of Food and Agriculture [ILLU-802-909 and ILLU-483-625], the College of ACES and the National Center for Supercomputing Applications at the University of Illinois.

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JOURNAL

Evolutionary Bioinformatics

DOI

10.1177/11769343231169377 

Avian influenza: new aspects of an old threat

From seasonal phenomenon linked to migratory birds in some regions to a constant global risk: highly pathogenic avian influenza has become a threat to wild birds as well as mammals causing issues for the poultry sector and public health.

Peer-Reviewed Publication

EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL (ECDC)

In Europe, epidemics of highly pathogenic avian influenza (HPAI) used to be a seasonal phenomenon associated with migratory waterfowl that were returning to their overwintering sites in the autumn. Since 2020, however, this picture has changed. HPAI viruses, particularly of the influenza A(H5) subtype, have caused the worst epidemics in birds observed to date, with more than 14,000 reported outbreaks and culling of roughly 96 million farmed birds in Europe. [1]

In their editorial published in Eurosurveillance, Cornelia Adlhoch (European Centre for Disease Prevention and Control, ECDC) and Francesca Baldinelli (European Food Safety Authority, EFSA) look at the rapid HPAI development in recent years with a move away from seasonality which has been accompanied by a large geographical extension: from west to east along the migratory bird routes towards south-east Asia. Recently, A(H5N1) virus introductions from Europe to North America was observed in an east to west spread via Iceland and Greenland for the first time from Europe to North America, progressing rapidly across large areas of Canada and the United States (US). Respectively, a north (Europe and North America) to south (Africa and Central/South America) spread during autumn bird migration occurred to as far down as the southern tip of Chile. [2]

They note that risk for human health is currently limited but warn that introduction of avian influenza viruses into mammalian populations could increase the risk of reassortment of influenza viruses that could adapt to mammals and spread among them: “With the ongoing global presence of A(H5) HPAI viruses, further sporadic spill-over events to humans cannot be excluded.”

Avian influenza: from virus evolution and diversification
The authors summarise that the recent “rapid spread of A(H5N1) viruses to many previously unaffected areas globally and their successful persistence during the summer months was likely facilitated by the ongoing evolution and reassortment with local low pathogenic avian (LPAI) viruses, leading to their adaptation to newly or previously very rarely affected wild bird species such as barnacle geese or sea birds.”

With this rapid and extensive spread, HPAI viruses affect wild bird populations e.g. in South America, where influenza A(H5N1) led to the death of more than 40% of the pelican population in Chile and Peru. In addition, Adlhoch and Baldinelli refer to reports from across the globe about transmission of HPAI to mammals such as minks and sea lions. Such events also increase the risk of the virus spilling over to pet animals through contact with for example dead or sick wild birds or mammals such as foxes.

So far, human infections with A(H5N1) have been reported only in a few countries with no or just mild symptoms (United Kingdom, Spain and the United States), related to exposure to infected birds or culling activities but also severe disease or even death (Chile, China, Ecuador and Vietnam) after exposure to sick or dead backyard poultry or to contaminated environment.

The authors highlight that “although currently circulating avian influenza viruses retain a preference for avian-type receptors, different mutations associated with transmission to and pathogenicity in mammals have been observed. These mutations were detected sporadically in infected wild and domestic birds and more often emerged upon transmission events to mammals.”

To tackle the threat of avian influenza, they conclude “a One Health approach is needed through: rapid sharing of information about outbreaks, provision of sequence data and reference viruses, and close collaboration between the different sectors locally and globally. Communication campaigns may help to increase awareness in the population and recognise avian influenza viruses as a threat to animal and human health, in order to reduce the risk of contact with potentially infected animals.”

----Ends----

References/notes to editors:
[1] Avian influenza (AI) is a highly contagious viral disease that affects both domestic and wild birds. AI viruses have also been isolated, although less frequently, from mammalian species, including humans. This complex disease is caused by viruses divided into multiple subtypes (i.e. H5N1, H5N3, H5N8 etc.) whose genetic characteristics rapidly evolve. See: https://www.woah.org/en/disease/avian-influenza/

The most significant impacts of influenza viruses on humans are those arising from the influenza A strains. The natural reservoir of influenza A strains is a diverse pool of viruses among aquatic wild bird populations – the AI viruses. These viruses are of high pathogenicity (HPAI) and low pathogenicity (LPAI), according to their severity in the avian species they usually infect. See: https://www.ecdc.europa.eu/en/avian-influenza

[2] Adlhoch Cornelia, Baldinelli Francesca. Avian influenza, new aspects of an old threat. Euro Surveill. 2023;28(19):pii=2300227. Available from: https://doi.org/10.2807/1560-7917.ES.2023.28.19.2300227

[3] Avian influenza overview March – April 2023, EFSA Journal 2023;21(5):8039. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/8039

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JOURNAL

Eurosurveillance

DOI

10.2807/1560-7917.ES.2023.28.19.2300227 

ARTICLE TITLE

Avian influenza, new aspects of an old threat

ARTICLE PUBLICATION DATE

11-May-2023

The brains of modern dog breeds are larger than those of ancient breeds

Domestication has reduced, modern-day demands have increased the brain size of dogs

Peer-Reviewed Publication

EÖTVÖS LORÁND UNIVERSITY (ELTE), FACULTY OF SCIENCE

 

IMAGE: MODERN DOG BREEDS THAT ARE GENETICALLY MORE DISTANT FROM WOLVES HAVE A RELATIVELY LARGER BRAIN SIZE COMPARED TO ANCIENT BREEDS THAT ARE THOUSANDS OF YEARS OLD, ACCORDING TO THE FINDINGS OF HUNGARIAN AND SWEDISH RESEARCHERS. view more 

CREDIT: PHOTO: BENCE JÁRDÁNY

Modern dog breeds that are genetically more distant from wolves have a relatively larger brain size compared to ancient breeds that are thousands of years old, according to the findings of Hungarian and Swedish researchers. The increase in brain size cannot be attributed to the roles or life history characteristics of the breeds, suggesting that it is likely influenced by urbanization and a more complex social environment.

Even today, the known four hundred dog breeds have developed relatively quickly and exhibit great diversity, making them a treasure trove for researchers interested in rapid changes within a species. Scientists have long been curious about the factors that affect brain size because the human brain is unusually large in comparison to body size. Comparing the various dog breeds can help answer some questions.

Is there a correlation between brain size and the specific tasks for which a breed was bred? Are there differences, for example, between lap dogs and hunting dogs? Or is it more influenced by life expectancy and the challenges of offspring rearing? What we know for certain is that

 thinking and cognitive processes require a lot of energy, and maintaining a larger brain is costly.

 László Zsolt Garamszegi, an evolutionary biologist at the Ecological Research Centre in Hungary, has been studying the evolution of brain size for a long time. "The brains of domesticated animals can be up to twenty percent smaller than those of their wild ancestors. The likely reason for this is that the lives of domesticated species are simpler compared to those of their wild counterparts. In the safe environment provided by humans, there is no need to fear predator attacks or hunt for food. Therefore, there is no need to sustain the energetically costly large brain, and the freed-up energy can be directed towards other purposes, such as producing more offspring, which is important for domesticated animals.”

Niclas Kolm, at  Stockholm University, focuses on brain evolution and the link between variation in brain morphology and behaviour. “Different dog breeds live in varying levels of social complexity and perform complex tasks, which likely require a larger brain capacity. Therefore, we hypothesize that the selective pressures on the brain can vary within the dog species, and we may find differences in brain size among breeds based on the tasks they perform or their genetic distance from wolves."

This is the first comprehensive study regarding the brain size of different dog breeds, and its preparation took several decades.

Tibor Csörgő, a senior research fellow at the Department of Anatomy, Cell and Developmental Biology at Eötvös Loránd University (ELTE), has been collecting skulls for decades. CT scans of the skulls were performed by Medicopus Nonprofit Ltd. in Kaposvár.

Based on the CT images, veterinarian Kálmán Czeibert reconstructed the brains and determined their exact volume. This invaluable collection was complemented by the Canine Brain and Tissue Bank, operated by ELTE for the past seven years, which enabled the verification of brain volumes calculated from skull images using actual brains. In the end, data was gathered from 865 individuals representing 159 dog breeds, with 48 specimens representing wolves.

According to the results published in the journal Evolution, wolves have an average brain volume of 131 cm3, associated with an average body weight of 31 kg. In the case of dogs in a similar weight category, the brain volume is only about three-quarters of that, approximately 100 cm3. This confirms that domestication has also led to a decrease in brain size in dogs. However, what surprised researchers is that the further a dog breed is genetically distant from wolves, the larger its relative brain size becomes. Contrary to expectations, the original role of the breeds, average litter size, and life expectancy are independent of brain size.

"The domestication of dogs began approximately twenty-five thousand years ago, but for ten thousand years, dogs and wolves did not differ in appearance. Many ancient breeds, such as sled dogs, still resemble wolves today. However, the transition to settlement, agriculture, pastoralism, and the accumulation of wealth offered various tasks for dogs, requiring guard dogs, herding dogs, hunting dogs, and even lap dogs. However, a significant portion of the distinct-looking breeds known today has only emerged since the industrial revolution, primarily in the last two centuries, as dog breeding has become a kind of hobby," says Enikő Kubinyi, a senior research fellow at the Department of Ethology at ELTE.

"The results show that the breeding of modern dog breeds has been accompanied by an increase in brain size compared to ancient breeds. We couldn't explain this based on the tasks or life history characteristics of the breeds, so we can only speculate about the reasons. Perhaps the more complex social environment, urbanization, and adaptation to more rules and expectations have caused this change, affecting all modern breeds."

These findings are supported by research indicating that ancient breeds known for their independence are less attentive to human cues and bark less, thus exhibiting differences in visual and acoustic communication compared to modern breeds.

Domestication has reduced, modern-day demands have increased the brain size of dogs

CREDIT

made by Kálmán Czeibert

Original publication: László Zsolt Garamszegi, Enikő Kubinyi, Kálmán Czeibert, Gergely Nagy, Tibor Csörgő, Niclas Kolm, Evolution of relative brain size in dogs – no effects of selection for breed function, litter size or longevity, Evolution, 2023, qpad063, https://doi.org/10.1093/evolut/qpad063

Funding: The study was supported by the Hungarian Academy of Sciences via a grant to the Hungarian Academy of Sciences (grant no. PH1404/21) and National Brain Programme 3.0 (NAP2022-I-3/2022), and by the National Research, Development and Innovation Office (grant no. 2019-2.1.11-TÉT-2020-00109) and Swedish Research Council (grant no. 2021-04476).

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JOURNAL

Evolution

DOI

10.1093/evolut/qpad063 

ARTICLE TITLE

Evolution of relative brain size in dogs—no effects of selection for breed function, litter size, or longevity

Resistant fungal species spreads

Peer-Reviewed Publication

UNIVERSITY OF WÜRZBURG

Among the yeasts from the Candida genus that cause infections in humans, the species Candida auris is still relatively new: this species was only described in 2009, and to date no evidence has been found before the 1990s. It is unclear what ecological niche C. auris colonizes and why human infections have increased since around the turn of the millennium.

Treatment of C. auris infections is greatly complicated by the pathogen's potential to develop resistance to all available antifungal classes. In addition, unlike other Candida species, C. auris can be efficiently transmitted from patient to patient via direct and indirect contact, leading to hospital outbreaks that are difficult to control.

Dramatic increase in the USA

Such outbreaks have now been observed worldwide, including in England, Spain and Italy. In April 2023, a dramatic increase in C. auris infections was shown for the U.S., along with further resistance development. A recent analysis by the European Centre for Disease Prevention and Control also shows a significant increase in case numbers for Europe.

As a result, the U.S. Centers for Disease Control classify C. auris as an "urgent threat" - the highest prioritization category within multidrug-resistant pathogens. In the 2023 list published by the World Health Organization for prioritizing fungi that cause human infections, C. auris is also grouped as one of only four pathogens in the highest priority level.

Increase in case numbers also in Germany

In Germany, there have only been isolated cases in which C. auris has been detected since 2015. However, an analysis now published in the Deutsches Ärzteblatt shows that the number of cases has also increased in Germany in recent years. Responsible for this study were Dr. Alexander Aldejohann from the Institute for Hygiene and Microbiology at the Julius-Maximilians-Universität Würzburg (JMU) and scientists from the National Reference Center for Invasive Fungal Infections (NRZMyk) and the Robert Koch Institute. Also involved was Professor Oliver Kurzai, Director of the Institute of Hygiene and Microbiology and Head of the NRZMyk.

The study is based on a comparison of C. auris data from the NRZMyk and the antibiotic resistance surveillance network of the Robert Koch Institute. A total of 43 C. auris cases were recorded in the two databases by the end of 2022. Colonization was detected in 19 cases and infection requiring therapy in 16 cases. In almost 42 percent of the cases, a stay abroad was documented shortly before the detection of infection.

Resistant to common drugs

80 percent of the fungal strains available at NRZMyk were highly resistant to fluconazole, a commonly used antifungal agent. In one case, there was resistance to echinocandin, a comparatively new class of substances for the treatment of fungal infections. The data analysis also recorded probable nosocomial transmissions in Germany for 2021 and 2022 - i.e. infections contracted by patients in connection with a medical procedure, for example in hospitals, care facilities or outpatient practices.

In summary, the authors conclude that the absolute number of C. auris infections in Germany remains low. However, the significant increase in the number of infections during the past two years and the detection of the first transmission events in Germany should, in their opinion, be interpreted as an alarm signal.

Comments on the publication

"Compared to other European countries such as Spain, Italy or Great Britain, the case numbers in our country are fortunately still low. We must do everything we can to keep it that way for as long as possible - our experience shows that any infection with Candida auris is difficult to treat and potentially life-threatening for patients. However, the good news at the moment is that no patient in a German hospital has to be afraid of becoming infected with Candida auris." (Dr. A. Aldejohann, Specialist in Microbiology, Virology and Infectious Disease Epidemiology, Institute of Hygiene and Microbiology, University of Würzburg)

"Our analyses show - fortunately still at a very low level - a significant increase in C. auris imports into Germany. At the same time, we were able to prove that the cases are currently not completely recorded in any database - we have to assume an unreported number. In view of the fact that we are also already finding the first transmission events in Germany, I have recommended to the Robert Koch Institute the introduction of a statutory laboratory reporting requirement for the detection of C. auris. In my view, this can be implemented with reasonable effort and, in addition to a precise recording of the epidemiology, would also make it possible to initiate infection protection measures at an early stage in the event of detection." (Prof. Dr. Oliver Kurzai, Chair of Medical Microbiology and Mycology, University of Würzburg and Head, NRZMyk)

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JOURNAL

Deutsches Ärzteblatt Online

DOI

10.3238/arztebl.m2023.0047 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

Rise in Candida auris cases and first nosocomial transmissions in Germany

ARTICLE PUBLICATION DATE

11-May-2023

Meeting more UK Government dietary guidelines during childhood could improve future cardiometabolic health, new research suggests.

Peer-Reviewed Publication

UNIVERSITY OF BRISTOL

The study, led by researchers from University of Bristol, is based on data from the world-renowned longitudinal health study, Children of the 90s (officially known as the Avon Longitudinal Study of Parents and Children, ALSPAC). The findings have been recently published in the British Journal of Nutrition.

The researchers assessed how well school-age children in the study complied to key UK Government dietary recommendations and then analysed the relationship between meeting these dietary recommendations during childhood and future cardiometabolic health.

An Eatwell Guide score (C-EWG score) was calculated when the participants were 7, 10 and 13 years old, to assess how well their habitual diet aligned to nine dietary recommendations represented within the Eatwell Guide. Cardiometabolic health was evaluated when these same participants were 17 and 24 years old, by using a cardiometabolic (heart/diabetes) risk score, which took into account the participant’s blood levels of certain fats, their blood pressure, insulin resistance and body fat.

Dr Genevieve Buckland, lead author of the study, from Bristol Medical School, said: “In general, the majority of the children in the study didn’t meet the dietary guidelines for many key foods and nutrients, because their diets contained too much saturated fat, sugar and salt and not enough fruit and vegetables, fibre and fish, particularly oily fish.”

The study also found that almost a third of the children in the study only met one out of nine key Eatwell Guide dietary recommendations, while 12-15% didn’t meet any of them. Children who met fewer dietary recommendations were more likely to come from a lower-socio-economic position and have mothers who were overweight or obese.

“A key finding was that children with diets which were more in line with UK guidelines had better cardiometabolic health when they were young adults. For example, children who met three or more dietary recommendations at 7 years had a lower cardiometabolic risk score at 24 years compared to those who didn’t meet any dietary recommendations. This reduction was largely driven by lower levels of body fat, cholesterol, blood pressure and insulin resistance,” says Dr Buckland.

The research adds to the evidence on the health benefits of following UK Government dietary recommendations from childhood and highlights the importance of creating healthy dietary habits from young ages to maintain future cardiovascular health.

Dr Buckland explains that: “The large gap between what school-age children in this cohort were eating and what they should be eating, according to Government dietary guidelines, implies that a huge amount of work still needs to be done to help UK children adopt healthier eating habits. Public health initiatives and policies particularly need to target children and their parents from lower socio-economic positions, because poorer dietary habits amongst these groups of children could be contributing to social inequalities in cardiovascular health later in life.”

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JOURNAL

British Journal Of Nutrition

DOI

10.1017/S0007114523000685 

ARTICLE TITLE

Prospective association between adherence to UK dietary guidelines in school-age children and cardiometabolic risk markers in adolescence/early adulthood in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort