Throughout nature, at all scales, you can find examples of chirality — or handedness. Imagine trying to eat a sandwich with two hands that were not enantiomers — non-superimposable mirror images — of each other. Consider the pharmacological disasters caused by administering the wrong drug enantiomer or, at a subatomic scale, the importance of the concept of parity in particle physics. Now, thanks to a new study led by researchers at Paul Scherrer Institute PSI, we know that phonons can also possess this property.

A phonon is a quasiparticle that describes the collective vibrational excitations of the atoms in a crystal lattice; imagine it as the Irish Riverdance of the atoms. Physicists have predicted that if phonons can demonstrate chirality they could have important implications on the fundamental physical properties of materials. With the rapid rise in recent years of research into topological materials that exhibit curious electronic and magnetic surface properties, interest in chiral phonons has grown. Yet, experimental proof for their existence has remained elusive.

What makes phonons chiral is the steps of their dance. In the new study, the atomic vibrations dance a twist that moves forwards like a corkscrew. This corkscrew motion is one of the reasons there has been such a drive to discover the phenomenon. If phonons can revolve in this way, like the coil of wire that forms a solenoid, perhaps they could create a magnetic field in a material.

A new slant on the problem

It is this possibility that motivated the group of Urs Staub at PSI, who led the study. “It is because we are at the juncture between ultrafast X-ray science and materials research that we could approach the problem from a different angle,” he says. The researchers are interested in manipulating chiral modes of materials using chiral light — light that is circularly polarised.

It was using such light that the researchers could make their proof. Using quartz, one of the best-known minerals whose atoms — silicon and oxygen — form a chiral structure, they showed how circularly polarised light coupled to chiral phonons. To do this, they used a technique known as resonant inelastic X-ray scattering (RIXS) at the Diamond Light Source in the UK. This was complemented with supporting theoretical descriptions of how the process would create and enable the detection of chiral phonons from groups at the ETH Zurich (Carl Romao and Nicola Spaldin) and MPI Dresden (Jeroen van den Brink).

“It doesn’t usually work like this in science!”

In their experiment, circularly polarised light shines on quartz. The photons of light possess angular momentum, which they transfer to the atomic lattice, launching the vibrations into their corkscrew motion. The direction that the phonons revolve depends on the intrinsic chirality of the quartz crystal. As the phonons revolve, they release energy in the form of scattered light, which can be detected.

Imagine standing on a roundabout and throwing a Frisbee. If you throw the Frisbee with the same direction of movement as the roundabout, you would expect it to whizz. Throw it the other way and it will spin less, as the angular momentum of the roundabout and the Frisbee will cancel out. In the same way, when the circularly polarised light twists the same way as the phonon it excites, the signal is enhanced, and chiral phonons could be detected.

A well-planned experiment, careful theoretical calculations, and then something strange happened: almost everything went according to plan. As soon as they analysed the results, the difference in response as the chirality of the light flipped was undeniable.

“The results were convincing almost immediately, especially when we compared the difference with the other quartz enantiomers,” remembers PSI scientist and publication first-author Hiroki Ueda. Sitting at his computer to analyse the data, Ueda was the first person to see the results: “I kept checking my analysis codes to make sure it was true.” Staub emphasises, “It’s not normal! It doesn’t usually work like this in science!”

Beautifully simple

During the quest for chiral phonons, there have been several false alarms. Will this settle the debate? “Yes, I think so, that’s the beauty of this piece of work,” believes Staub, whose opinion was shared by the referees at Nature. “Because it’s simple, and beautiful and straightforward. It’s obvious. It’s so simple, it’s obvious that this is the chiral motion.”

While our Jupiter is far away from the sun, hot Jupiters are gas giant planets that closely orbit stars outside our solar system for an orbital period of less than 10 days. Previous studies suggested they rarely have any nearby companion planets, leading scientists to believe that hot Jupiters formed and evolved through a violent process that expelled other planets from the area as they moved closer to their host stars. The research team’s findings reveal that hot Jupiters do not always orbit alone.

“Our research shows that at least a fraction of hot Jupiters cannot form through a violent process,” said Songhu Wang, assistant professor of astronomy in the College of Arts and Sciences. “This is a significant contribution to advance our understanding of hot Jupiter formation, which can help us learn more about our own solar system.”

Wang presented the results of the research at the June 2023 meeting of the American Astronomical Society in Albuquerque, New Mexico.

Researchers analyzed the full, four-year data set for hot and warm Jupiters from NASA’s Kepler Mission. Warm Jupiters have a longer orbital period that ranges from 10 to 300 days. Researchers used transit timing variations to determine that at least 12% of hot Jupiters and 70% of warm Jupiters have a nearby planetary companion orbiting their host stars.

Wang and his collaborators combined their results with existing observational constraints to propose a new framework for explaining the evolution of hot and warm Jupiters and why some have companion planets. They determined that the makeup of hot and warm Jupiter systems depends on the occurrence of gas giants in the system, which impacts how much the planets interact and migrate.

The findings provide a launching point into future research about exoplanets and our solar system’s planets.

“The ultimate goal for astronomers is to set our solar system into the bigger picture — ‘Are we unique?'” Wang said. “This helps us to understand why we don’t have a hot Jupiter in our solar system.”

Additional collaborators are Dong-Hong Wu, lecturer in the Department of Physics at Anhui Normal University, and Malena Rice, 51 Pegasi b Fellow at the Massachusetts Institute of Technology and incoming professor at Yale University.

Wang has long been interested in the configurations and demographics of exoplanets. He uses observational research to try to understand their dynamics and origins, helping astronomers better understand how our solar system fits into a larger cosmic context.

The primary way that the United States has protected its fisheries is through the Magnuson-Stevens Act, which was modernized in 1996 to foster the long-term biological and economic sustainability of marine fisheries. However, the reauthorization of this act has been stalled in Congress for a decade, as some politicians blame the law for being too stringent, leading to what they call “underfishing.”

The University of Delaware’s Kimberly Oremus recently served as a lead author on a paper published in Science that examined U.S. fishing policy. The paper found that the Magnuson-Stevens Act is not constraining most fisheries, and that there are various other reasons that lead to certain fish species being less fished.

Oremus, assistant professor in the School of Marine Science and Policy, and Eyal Frank, an assistant professor at the University of Chicago Harris School of Public Policy, served as the lead authors on the paper.

The researchers examined two decades of data on 170 U.S. fish stocks. These 170 managed fish stocks represent 85% of the U.S. marine commercial fish landings.

In the study, Oremus, Frank, and their other co-authors examined the assertion of critics of U.S. fishing law that it is too stringent and unnecessarily leaves too many fish in the water.

They found that the main reason about half of the fish stocks in the U.S. are considered “underfished” is due to pure economics — fishers are not harvesting the fish because there is not enough demand for them.

Just four fish species — the Eastern Bering Sea walleye pollock, Atlantic sea scallop, Gulf of Mexico brown shrimp and Gulf of Mexico white shrimp — make up the majority of the revenue of those stocks that the researchers characterized as potentially less utilized and fished. Of those, the majority of the revenue came from just one species: the walleye pollock, the catch of which is not constrained by the Magnuson-Stevens Act.

Other, healthy fish stocks are being left in the water because they could not be profitably caught without also catching other fish species that are depleted.

“Some healthy stocks are constrained by the Magnuson-Stevens Act because they are often caught with other stocks that are depleted,” Oremus said. “Some stocks are constrained by other laws such as the Marine Mammal Protection Act or the Pacific Halibut Treaty with Canada. Some stocks are constrained by both market forces and policies, such as our Gulf of Mexico shrimp stocks that are struggling to compete with the price of imported shrimp coming from less regulated countries.”

While political rhetoric has focused on laws that protect fisheries — such as the Magnuson-Stevens Act — as the main culprit in underfishing, the researchers said it is important to take a nuanced view of the picture and view fisheries on a case-by-case basis.

“Targeting the Magnuson-Stevens Act will not change some of these outcomes,” Frank said. “It is important to understand the multitude of factors involved. Simply relaxing fishery management targets under the law will most likely fail to increase utilization in many of the marine fisheries that appear to be underutilized at face value.”

With changes to the environment and overfishing still a big concern in other parts of the world, it is critical to have science-based fisheries laws in place in order to sustain fish stocks moving forward, Oremus said.

“On average, we find that less fished stocks were less fished six years before the law was passed in 1996, and their share of revenue has remained steady from 1990-2015,” Oremus said. “Though no law is perfect, the law appears to be attempting to balance the needs of fishers, other stakeholders, and the long-term conservation of the resource.”

A multi-institution research team including Cornell University has developed a new suite of computational genetic tools to address the genetic effects of interbreeding between humans of non-African ancestry and Neanderthals that took place some 50,000 years ago. (The study applies only to descendants of those who migrated from Africa before Neanderthals died out, and in particular, those of European ancestry.)

In a study published in eLife, the researchers reported that some Neanderthal genes are responsible for certain traits in modern humans, including several with a significant influence on the immune system. Overall, however, the study shows that modern human genes are winning out over successive generations.

“Interestingly, we found that several of the identified genes involved in modern human immune, metabolic and developmental systems might have influenced human evolution after the ancestors’ migration out of Africa,” said study co-lead author April (Xinzhu) Wei, an assistant professor of computational biology in the College of Arts and Sciences. “We have made our custom software available for free download and use by anyone interested in further research.”

Using a vast dataset from the UK Biobank consisting of genetic and trait information of nearly 300,000 Brits of non-African ancestry, the researchers analyzed more than 235,000 genetic variants likely to have originated from Neanderthals. They found that 4,303 of those differences in DNA are playing a substantial role in modern humans and influencing 47 distinct genetic traits, such as how fast someone can burn calories or a person’s natural immune resistance to certain diseases.

Unlike previous studies that could not fully exclude genes from modern human variants, the new study leveraged more precise statistical methods to focus on the variants attributable to Neanderthal genes.

While the study used a dataset of almost exclusively white individuals living in the United Kingdom, the new computational methods developed by the team could offer a path forward in gleaning evolutionary insights from other large databases to delve deeper into archaic humans’ genetic influences on modern humans.

“For scientists studying human evolution interested in understanding how interbreeding with archaic humans tens of thousands of years ago still shapes the biology of many present-day humans, this study can fill in some of those blanks,” said senior investigator Sriram Sankararaman, an associate professor at the University of California, Los Angeles. “More broadly, our findings can also provide new insights for evolutionary biologists looking at how the echoes of these types of events may have both beneficial and detrimental consequences.”

The other co-lead author on the study is Christopher Robles, postdoctoral researcher at UCLA. Additional authors are UCLA doctoral student Ali Pazokitoroudi; Andrea Ganna of Massachusetts General Hospital and the Broad Institute of MIT and Harvard; Alexander Gusev and Arun Durvasula of Harvard Medical School; Steven Gazal of USC; Po-Ru Loh of the Broad Institute of MIT and Harvard; and David Reich of Harvard University.

The research was supported by grants from the National Institutes of Health and the National Science Foundation, with additional funding from an Alfred P Sloan Research Fellowship and a gift from the Okawa Foundation. Other authors received funding support from the Paul G. Allen Frontiers Group, the John Templeton Foundation, the Howard Hughes Medical Institute, the Burroughs Wellcome Fund and the Next Generation Fund at the Broad Institute of MIT and Harvard.

The same study also found that taurine supplements can slow down the aging process in worms, mice, and monkeys and can even extend the healthy lifespans of middle-aged mice by up to 12%.

The study was published June 8 in Science.

“For the last 25 years, scientists have been trying to find factors that not only let us live longer, but also increase healthspan, the time we remain healthy in our old age,” says the study’s leader, Vijay Yadav, PhD, assistant professor of genetics & development at Columbia University Vagelos College of Physicians and Surgeons.

“This study suggests that taurine could be an elixir of life within us that helps us live longer and healthier lives.”

Anti-aging molecules within us

Over the past two decades, efforts to identify interventions that improve health in old age have intensified as people are living longer and scientists have learned that the aging process can be manipulated.

Many studies have found that various molecules carried through the bloodstream are associated with aging. Less certain is whether these molecules actively direct the aging process or are just passengers going along for the ride. If a molecule is a driver of aging, then restoring its youthful levels would delay aging and increase healthspan, the years we spend in good health.

Taurine first came into Yadav’s view during his previous research into osteoporosis that uncovered taurine’s role in building bone. Around the same time, other researchers were finding that taurine levels correlated with immune function, obesity, and nervous system functions.

“We realized that if taurine is regulating all these processes that decline with age, maybe taurine levels in the bloodstream affect overall health and lifespan,” Yadav says.

Taurine declines with age, supplementation increases lifespan in mice

First, Yadav’s team looked at levels of taurine in the bloodstream of mice, monkeys, and people and found that the taurine abundance decreases substantially with age. In people, taurine levels in 60-year-old individuals were only about one-third of those found in 5-year-olds.

“That’s when we started to ask if taurine deficiency is a driver of the aging process, and we set up a large experiment with mice,” Yadav says.

The researchers started with close to 250 14-month-old female and male mice (about 45 years old in people terms). Every day, the researcher fed half of them a bolus of taurine or a control solution. At the end of the experiment, Yadav and his team found that taurine increased average lifespan by 12% in female mice and 10% in males. For the mice, that meant three to four extra months, equivalent to about seven or eight human years.

Taurine supplements in middle age improves health in old age

To learn how taurine impacted health, Yadav brought in other aging researchers who investigated the effect of taurine supplementation on the health and lifespan in several species.

These experts measured various health parameters in mice and found that at age 2 (60 in human years), animals supplemented with taurine for one year were healthier in almost every way than their untreated counterparts.

The researchers found that taurine suppressed age-associated weight gain in female mice (even in “menopausal” mice), increased energy expenditure, increased bone mass, improved muscle endurance and strength, reduced depression-like and anxious behaviors, reduced insulin resistance, and promoted a younger-looking immune system, among other benefits.

“Not only did we find that the animals lived longer, we also found that they’re living healthier lives,” Yadav says.

At a cellular level, taurine improved many functions that usually decline with age: The supplement decreased the number of “zombie cells” (old cells that should die but instead linger and release harmful substances), increased survival after telomerase deficiency, increased the number of stem cells present in some tissues (which can help tissues heal after injury), improved the performance of mitochondria, reduced DNA damage, and improved the cells’ ability to sense nutrients.

Similar health effects of taurine supplements were seen in middle-aged rhesus monkeys, which were given daily taurine supplements for six months. Taurine prevented weight gain, reduced fasting blood glucose and markers of liver damage, increased bone density in the spine and legs, and improved the health of their immune systems.

Randomized clinical trial needed

The researchers do not know yet if taurine supplements will improve health or increase longevity in humans, but two experiments they conducted suggest taurine has potential.

In the first, Yadav and his team looked at the relationship between taurine levels and approximately 50 health parameters in 12,000 European adults aged 60 and over. Overall, people with higher taurine levels were healthier, with fewer cases of type 2 diabetes, lower obesity levels, reduced hypertension, and lower levels of inflammation. “These are associations, which do not establish causation,” Yadav says, “but the results are consistent with the possibility that taurine deficiency contributes to human aging.”

The second study tested if taurine levels would respond to an intervention known to improve health: exercise. The researchers measured taurine levels before and after a variety of male athletes and sedentary individuals finished a strenuous cycling workout and found a significant increase in taurine among all groups of athletes (sprinters, endurance runners, and natural bodybuilders) and sedentary individuals.

“No matter the individual, all had increased taurine levels after exercise, which suggests that some of the health benefits of exercise may come from an increase in taurine,” Yadav says.

Only a randomized clinical trial in people will determine if taurine truly has health benefits, Yadav adds. Taurine trials are currently underway for obesity, but none are designed to measure a wide range of health parameters.

Other potential anti-aging drugs — including metformin, rapamycin, and NAD analogs — are being considered for testing in clinical trials.

“I think taurine should also be considered,” Yadav says. “And it has some advantages: Taurine is naturally produced in our bodies, it can be obtained naturally in the diet, it has no known toxic effects (although it’s rarely used in concentrations used ), and it can be boosted by exercise.

“Taurine abundance goes down with age, so restoring taurine to a youthful level in old age may be a promising anti-aging strategy.”

Above 45 kg, the researchers found evidence for decreasing abundance with increasing size, a pattern that aligns with the ecological ‘rule of metabolic scaling’, whereby larger species have lower population densities compared to smaller ones. A deviation from the predicted ecological pattern was that mammals between ~15 and 45 kg were far less numerous than expected, both in living and fossil communities. They interpreted this as a signature of savanna habitats (where monkeys and small forest-living antelopes are rare).

The big surprise came when the researchers examined how size-abundance distributions changed over time. They discovered that earlier communities, older than ~4 million years ago, had a considerably higher number of large-sized individuals and a greater proportion of total biomass in larger size categories, than did younger communities. The high abundance of large individuals in these fossil African communities — with some individual elephants reaching sizes over 10 tons — is unparalleled in ecosystems today. Since that time, there has been a gradual loss of large-sized individuals from the fossil record, reflecting the long-term decline of late Pliocene and Pleistocene large mammal diversity, and resulting in the impoverished and ‘miniaturized’ communities we know today.

The study confirms recent work arguing for the deep-time antiquity of African megafaunal losses and challenging the idea that the decline of African megafauna was primarily driven by human activities. While the spread of humans across the globe during the late Pleistocene and Holocene (the last ~100,000 years) coincided with major extinction of many large animals, the research supports the idea that megafaunal losses in Africa began much earlier, around 4 million years ago, and long before humans learned to engage in efficient hunting. Instead, the study highlights environmental factors, such as the long-term decrease in global temperatures and the expansion of tropical grasslands, as potential drivers of megafaunal extinctions.

The study also found that the loss of large individuals and the restructuring of biomass distributions in African large mammal communities could have been linked to decreases in primary productivity. Using an established relationship between the types of mammalian tooth shapes (morphological traits) and plant productivity (net primary productivity) today, the researchers calculated productivity for African communities in the past. They found an approximately two-thirds decrease in productivity since the Late Miocene (> 5 million years ago), a pattern observed globally, and that could have significantly diminished the carrying capacity of large mammal communities, leading to reduced diversity and accelerated extinction of large species.

The research opens new avenues for understanding the dynamics of ecosystems and the complex interactions between individuals, species, and their environment. By analyzing fossil abundance data and incorporating size-based approaches, scientists can gain valuable insights into the ecological dynamics underlying extinction.

The publication of this scientific paper marks a significant milestone in our understanding of African megafaunal extinctions and the restructuring of ecosystems over geological time scales. Bibi and Cantalapiedra’s findings have the potential to inform conservation efforts and enhance our ability to predict and manage the consequences of biodiversity loss in the face of environmental change.

In the new study, led by Imperial College London and published today in Science, researchers ranked 90% of global net-zero greenhouse gas emissions pledges as providing low confidence in their full implementation.

The researchers recommend nations make their targets legally binding and back them up with long-term plans and short-term implementation policies to increase the likelihood of avoiding the worst impacts of climate change.

Lead researcher Professor Joeri Rogelj, director of research for the Grantham Institute at Imperial, said: “Climate policy is moving from setting ambitious targets to implementing them. However, our analysis shows most countries do not provide high confidence that they will deliver on their commitments. The world is still on a high-risk climate track, and we are far from delivering a safe climate future.”

Assigning confidence

Climate goals set out in the Paris Agreement include keeping temperature rises well below 2°C above the average temperature before the industrial revolution and ideally below 1.5°C. The main way to achieve this is the reach ‘net-zero’ greenhouse gas emissions as soon as possible, where any remaining emissions are effectively offset.

Most countries have set net-zero goals and Nationally Determined Contributions (NDCs) — non-binding national plans proposing climate actions. Taking these plans at face value, and assuming they will all be fully implemented, gives the world a chance of keeping warming to 1.5-2 degrees C. But taking current policies only, with no implementation of net-zero pledges, means models predict temperature rises could be as much as 2.5-3 degrees C by 2100, with warming still increasing.

To reduce the uncertainty in which of these scenarios is likely to happen, the team, including researchers from the UK, Austria, USA, Netherlands, Germany, and Brazil, assigned a ‘confidence’ to each net-zero policy. They assessed 35 net zero targets, covering every country with more than 0.1% of current global greenhouse gas emissions.

The confidence assessment was based on three policy characteristics: whether the policy was legally binding, whether there was a credible policy plan guiding implementation, and whether short-term plans would already put emissions on a downward path over the next decade.

Based on this, policies were given ‘higher’, ‘lower’ or ‘much lower’ confidence of being fully implemented. Some regions scored highly, including the European Union, the United Kingdom and New Zealand, but around 90% scored ‘lower’ or ‘much lower’ confidence, including China and the US, which together account for more than 35% of current emissions.

Modelling emissions

From this assessment, the team modelled five scenarios of future greenhouse gas emissions and resulting temperatures. These were: considering only current policies (the most conservative scenario); only adding in policies that have a high confidence of being implemented; adding policies with high and low confidence; adding all policies regardless of confidence as if they are implemented; and a scenario where all policies are fully implemented and all NDCs are met (the most forgiving scenario).

The most conservative scenario had the largest uncertainty, with a range of 1.7-3°C and a median estimate of 2.6°C. The most optimistic scenario has a range of 1.6-2.1, with a median estimate of 1.7°C. This might suggest that, if all net-zero policies are fully implemented, the Paris Agreement goals are withing reach. However, with so many policies ranked in the low-confidence end of the scale, this would be wishful thinking in absence of further efforts.

Co-author Taryn Fransen, from the World Resources Institute in Washington DC, and the Energy and Resources Group at the University of California-Berkeley, said: “Climate change targets are by their nature ambitious — there’s no point in setting a target for a foregone conclusion. But implementation must follow.”

Catalysing action

Only twelve out of 35 net zero policies are currently legally binding, and the researchers say increasing this number would help ensure the policies survive long-term and catalyse action. Countries also need clear implementation pathways for different sectors, outlining exactly what changes are needed and where the responsibility lies.

Co-author Dr Robin Lamboll, from the Centre for Environmental Policy at Imperial, said: “Making targets legally binding is crucial to ensure long-term plans are adopted. We need to see concrete legislation in order to trust that action will follow from promises.”

The team included researchers from Imperial College London (UK) the International Institute for Applied Systems Analysis (Austria), the World Resources Institute (US), the University of California-Berkeley (US), the Netherlands Environmental Assessment Agency, the Institute for Environmental Studies (Netherlands), the NewClimate Institute (Germany), the Copernicus Institute of Sustainable Development (Netherlands), and the Universidade Federal do Rio de Janeiro (Brazil).

Emil Sierda, who was in charge of conducting the experiments at Radboud University: ‘A few years ago we had this crazy idea to build a quantum simulator. We wanted to create artificial molecules that resembled real molecules. So we developed a system in which we can trap electrons. Electrons surround a molecule like a cloud, and we used those trapped electrons to build an artificial molecule.’ The results the team found were astonishing. Sierda: ‘The resemblance between what we built and real molecules was uncanny.’

Changing molecules

Alex Khajetoorians, head of the Scanning Probe Microscopy (SPM) department at the Institute for Molecules and Materials of Radboud University: ‘Making molecules is difficult enough. What is often harder, is to understand how certain molecules react, for example how they change when they are twisted or altered.’ How molecules change and react is the basis of chemistry, and leads to chemical reactions, like the formation of water from hydrogen and oxygen. ‘We wanted to simulate molecules, so we could have the ultimate toolkit to bend them and tune them in ways that are nearly impossible with real molecules. In that way we can say something about real molecules, without making them, or without having to deal with the challenges they present, like their constantly changing shape.’

Benzene

Using this simulator, the researchers created an artificial version of one of the basic organic molecules in chemistry: benzene. Benzene is the starting component for a vast amount of chemicals, like styrene, which is used to make polystyrene. Khajetoorians: ‘By making benzene, we simulated a textbook organic molecule, and built a molecule that is made up of elements that are not organic.’ Above that: the molecules are 10 times bigger than their real counterparts, which makes them easier to work with.

Practical uses

The uses of this new technique are endless. Daniel Wegner, assistant professor within the SPM department: ‘We have only begun to imagine what we can use this for. We have so many ideas that it is hard to decide where to start.’ By using the simulator, scientists can understand molecules and their reactions much better, which will help in every scientific field imaginable. Wegner: ‘New materials for future computer hardware are really hard to make, for instance. By making a simulated version, we can look for the novel properties and functionalities of certain molecules and evaluate whether it will be worth making the real material.’ In the far future, all kinds of things may be possible: understanding chemical reactions step by step like in a slow-motion video, or making artificial single-molecule electronic devices, like shrinking the size of a transistor on a computer chip. Quantum simulators are even suggested to perform as quantum computers. Sierda: ‘But that’s a long way to go, for now we can start by beginning to understand molecules in a way we never understood before.’