Scientists show what loneliness looks like in the brain

Person sitting alone on bench

This holiday season will be a lonely one for many people as social distancing due to COVID-19 continues, and it is important to understand how isolation affects our health. A new study shows a sort of signature in the brains of lonely people that make them distinct in fundamental ways, based on variations in the volume of different brain regions as well as based on how those regions communicate with one another across brain networks.

A team of researchers examined the magnetic resonance imaging (MRI) data, genetics and psychological self-assessments of approximately 40,000 middle-aged and older adults who volunteered to have their information included in the UK Biobank: an open-access database available to health scientists around the world. They then compared the MRI data of participants who reported often feeling lonely with those who did not.

The researchers found several differences in the brains of lonely people. These brain manifestations were centred on what is called the default network: a set of brain regions involved in inner thoughts such as reminiscing, future planning, imagining and thinking about others. Researchers found the default networks of lonely people were more strongly wired together and surprisingly, their grey matter volume in regions of the default network was greater. Loneliness also correlated with differences in the fornix: a bundle of nerve fibres that carries signals from the hippocampus to the default network. In lonely people, the structure of this fibre tract was better preserved.

We use the default network when remembering the past, envisioning the future or thinking about a hypothetical present. The fact the structure and function of this network is positively associated with loneliness may be because lonely people are more likely to use imagination, memories of the past or hopes for the future to overcome their social isolation.

"In the absence of desired social experiences, lonely individuals may be biased towards internally-directed thoughts such as reminiscing or imagining social experiences. We know these cognitive abilities are mediated by the default network brain regions," says Nathan Spreng from The Neuro (Montreal Neurological Institute-Hospital) of McGill University, and the study's lead author. "So this heightened focus on self-reflection, and possibly imagined social experiences, would naturally engage the memory-based functions of the default network."

Loneliness is increasingly being recognized as a major health problem, and previous studies have shown older people who experience loneliness have a higher risk of cognitive decline and dementia. Understanding how loneliness manifests itself in the brain could be key to preventing neurological disease and developing better treatments.

"We are just beginning to understand the impact of loneliness on the brain. Expanding our knowledge in this area will help us to better appreciate the urgency of reducing loneliness in today's society," says Danilo Bzdok, a researcher at The Neuro and the Quebec Artificial Intelligence Institute, and the study's senior author.

 

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A 'super-puff' planet like no other

W. M. Keck Observatory in Hawaii

The core mass of the giant exoplanet WASP-107b is much lower than what was thought necessary to build up the immense gas envelope surrounding giant planets like Jupiter and Saturn, astronomers at Université de Montréal have found.

This intriguing discovery by Ph.D. student Caroline Piaulet of UdeM's Institute for Research on Exoplanets (iREx) suggests that gas-giant planets form a lot more easily than previously believed.

Piaulet is part of the groundbreaking research team of UdeM astrophysics professor Björn Benneke that in 2019 announced the first detection of water on an exoplanet located in its star's habitable zone.

Published today in the Astronomical Journal with colleagues in Canada, the U.S., Germany and Japan, the new analysis of WASP-107b's internal structure "has big implications," said Benneke.

"This work addresses the very foundations of how giant planets can form and grow," he said. "It provides concrete proof that massive accretion of a gas envelope can be triggered for cores that are much less massive than previously thought."

As big as Jupiter but 10 times lighter

WASP-107b was first detected in 2017 around WASP-107, a star about 212 light years from Earth in the Virgo constellation. The planet is very close to its star -- over 16 times closer than the Earth is to the Sun. As big as Jupiter but 10 times lighter, WASP-107b is one of the least dense exoplanets known: a type that astrophysicists have dubbed "super-puff" or "cotton-candy" planets.

Piaulet and her team first used observations of WASP-107b obtained at the Keck Observatory in Hawai'i to assess its mass more accurately. They used the radial velocity method, which allows scientists to determine a planet's mass by observing the wobbling motion of its host star due to the planet's gravitational pull. They concluded that the mass of WASP-107b is about one tenth that of Jupiter, or about 30 times that of Earth.

The team then did an analysis to determine the planet's most likely internal structure. They came to a surprising conclusion: with such a low density, the planet must have a solid core of no more than four times the mass of the Earth. This means that more than 85 percent of its mass is included in the thick layer of gas that surrounds this core. By comparison, Neptune, which has a similar mass to WASP-107b, only has 5 to 15 percent of its total mass in its gas layer.

"We had a lot of questions about WASP-107b," said Piaulet. "How could a planet of such low density form? And how did it keep its huge layer of gas from escaping, especially given the planet's close proximity to its star?

"This motivated us to do a thorough analysis to determine its formation history."

A gas giant in the making

Planets form in the disc of dust and gas that surrounds a young star called a protoplanetary disc. Classical models of gas-giant planet formation are based on Jupiter and Saturn. In these, a solid core at least 10 times more massive than the Earth is needed to accumulate a large amount of gas before the disc dissipates.

Without a massive core, gas-giant planets were not thought able to cross the critical threshold necessary to build up and retain their large gas envelopes.

How then do explain the existence of WASP-107b, which has a much less massive core? McGill University professor and iREx member Eve Lee, a world-renowned expert on super-puff planets like WASP-107b, has several hypotheses.

"For WASP-107b, the most plausible scenario is that the planet formed far away from the star, where the gas in the disc is cold enough that gas accretion can occur very quickly," she said. "The planet was later able to migrate to its current position, either through interactions with the disc or with other planets in the system."

Discovery of a second planet, WASP-107c

The Keck observations of the WASP-107 system cover a much longer period of time than previous studies have, allowing the UdeM-led research team to make an additional discovery: the existence of a second planet, WASP-107c, with a mass of about one-third that of Jupiter, considerably more than WASP-107b's.

WASP-107c is also much farther from the central star; it takes three years to complete one orbit around it, compared to only 5.7 days for WASP-107b. Also interesting: the eccentricity of this second planet is high, meaning its trajectory around its star is more oval than circular.

"WASP-107c has in some respects kept the memory of what happened in its system," said Piaulet. "Its great eccentricity hints at a rather chaotic past, with interactions between the planets which could have led to significant displacements, like the one suspected for WASP-107b."

 

Why crocodiles have changed so little since the age of the dinosaurs

Crocodile

New research by scientists at the University of Bristol explains how a 'stop-start' pattern of evolution, governed by environmental change, could explain why crocodiles have changed so little since the age of the dinosaurs.

Crocodiles today look very similar to ones from the Jurassic period some 200 million years ago. There are also very few species alive today -- just 25. Other animals such as lizards and birds have achieved a diversity of many thousands of species in the same amount of time or less.

Prehistory also saw types of crocodile we don't see today, including giants as big as dinosaurs, plant-eaters, fast runners and serpentine forms that lived in the sea.

In the new research, published today in the journal Nature Communications Biology, the scientists explain how crocodiles follow a pattern of evolution known as 'punctuated equilibrium'.

The rate of their evolution is generally slow, but occasionally they evolve more quickly because the environment has changed. In particular, this new research suggests that their evolution speeds up when the climate is warmer, and that their body size increases.

Lead author Dr Max Stockdale from the University of Bristol's School of Geographical Sciences, said: "Our analysis used a machine learning algorithm to estimate rates of evolution. Evolutionary rate is the amount of change that has taken place over a given amount of time, which we can work out by comparing measurements from fossils and taking into account how old they are.

"For our study we measured body size, which is important because it interacts with how fast animals grow, how much food they need, how big their populations are and how likely they are to become extinct."

The findings show that the limited diversity of crocodiles and their apparent lack of evolution is a result of a slow evolutionary rate. It seems the crocodiles arrived at a body plan that was very efficient and versatile enough that they didn't need to change it in order to survive.

This versatility could be one explanation why crocodiles survived the meteor impact at the end of the Cretaceous period, in which the dinosaurs perished. Crocodiles generally thrive better in warm conditions because they cannot control their body temperature and require warmth from the environment.

The climate during the age of dinosaurs was warmer than it is today, and that may explain why there were many more varieties of crocodile than we see now. Being able to draw energy from the sun means they do not need to eat as much as a warm-blooded animal like a bird or a mammal.

Dr Stockdale added: "It is fascinating to see how intricate a relationship exists between the earth and the living things we share it with. The crocodiles landed upon a lifestyle that was versatile enough to adapt to the enormous environmental changes that have taken place since the dinosaurs were around."

 

2020 tied for warmest year on record, NASA analysis shows

Thermometer and sky background

Earth's global average surface temperature in 2020 tied with 2016 as the warmest year on record, according to an analysis by NASA.

Continuing the planet's long-term warming trend, the year's globally averaged temperature was 1.84 degrees Fahrenheit (1.02 degrees Celsius) warmer than the baseline 1951-1980 mean, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. 2020 edged out 2016 by a very small amount, within the margin of error of the analysis, making the years effectively tied for the warmest year on record.

"The last seven years have been the warmest seven years on record, typifying the ongoing and dramatic warming trend," said GISS Director Gavin Schmidt. "Whether one year is a record or not is not really that important -- the important things are long-term trends. With these trends, and as the human impact on the climate increases, we have to expect that records will continue to be broken."

A Warming, Changing World

Tracking global temperature trends provides a critical indicator of the impact of human activities -- specifically, greenhouse gas emissions -- on our planet. Earth's average temperature has risen more than 2 degrees Fahrenheit (1.2 degrees Celsius) since the late 19th century.

Rising temperatures are causing phenomena such as loss of sea ice and ice sheet mass, sea level rise, longer and more intense heat waves, and shifts in plant and animal habitats. Understanding such long-term climate trends is essential for the safety and quality of human life, allowing humans to adapt to the changing environment in ways such as planting different crops, managing our water resources and preparing for extreme weather events.

Ranking the Records

A separate, independent analysis by the National Oceanic and Atmospheric Administration (NOAA) concluded that 2020 was the second-warmest year in their record, behind 2016. NOAA scientists use much of the same raw temperature data in their analysis, but have a different baseline period (1901-2000) and methodology. Unlike NASA, NOAA also does not infer temperatures in polar regions lacking observations, which accounts for much of the difference between NASA and NOAA records.

Like all scientific data, these temperature findings contain a small amount of uncertainty -- in this case, mainly due to changes in weather station locations and temperature measurement methods over time. The GISS temperature analysis (GISTEMP) is accurate to within 0.1 degrees Fahrenheit with a 95 percent confidence level for the most recent period.

Beyond a Global, Annual Average

While the long-term trend of warming continues, a variety of events and factors contribute to any particular year's average temperature. Two separate events changed the amount of sunlight reaching the Earth's surface. The Australian bush fires during the first half of the year burned 46 million acres of land, releasing smoke and other particles more than 18 miles high in the atmosphere, blocking sunlight and likely cooling the atmosphere slightly. In contrast, global shutdowns related to the ongoing coronavirus (COVID-19) pandemic reduced particulate air pollution in many areas, allowing more sunlight to reach the surface and producing a small but potentially significant warming effect. These shutdowns also appear to have reduced the amount of carbon dioxide (CO2) emissions last year, but overall CO2 concentrations continued to increase, and since warming is related to cumulative emissions, the overall amount of avoided warming will be minimal.

The largest source of year-to-year variability in global temperatures typically comes from the El Nino-Southern Oscillation (ENSO), a naturally occurring cycle of heat exchange between the ocean and atmosphere. While the year has ended in a negative (cool) phase of ENSO, it started in a slightly positive (warm) phase, which marginally increased the average overall temperature. The cooling influence from the negative phase is expected to have a larger influence on 2021 than 2020.

"The previous record warm year, 2016, received a significant boost from a strong El Nino. The lack of a similar assist from El Nino this year is evidence that the background climate continues to warm due to greenhouse gases," Schmidt said.

The 2020 GISS values represent surface temperatures averaged over both the whole globe and the entire year. Local weather plays a role in regional temperature variations, so not every region on Earth experiences similar amounts of warming even in a record year. According to NOAA, parts of the continental United States experienced record high temperatures in 2020, while others did not.

In the long term, parts of the globe are also warming faster than others. Earth's warming trends are most pronounced in the Arctic, which the GISTEMP analysis shows is warming more than three times as fast as the rest of the globe over the past 30 years, according to Schmidt. The loss of Arctic sea ice -- whose annual minimum area is declining by about 13 percent per decade -- makes the region less reflective, meaning more sunlight is absorbed by the oceans and temperatures rise further still. This phenomenon, known as Arctic amplification, is driving further sea ice loss, ice sheet melt and sea level rise, more intense Arctic fire seasons, and permafrost melt.

Land, Sea, Air and Space

NASA's analysis incorporates surface temperature measurements from more than 26,000 weather stations and thousands of ship- and buoy-based observations of sea surface temperatures. These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heating effects that could skew the conclusions if not taken into account. The result of these calculations is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.

NASA measures Earth's vital signs from land, air, and space with a fleet of satellites, as well as airborne and ground-based observation campaigns. The satellite surface temperature record from the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aura satellite confirms the GISTEMP results of the past seven years being the warmest on record. Satellite measurements of air temperature, sea surface temperature, and sea levels, as well as other space-based observations, also reflect a warming, changing world. The agency develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. NASA shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

 

How our brains track where we and others go

Crowd of people

 As COVID cases rise, physically distancing yourself from other people has never been more important. Now a new UCLA study reveals how your brain navigates places and monitors someone else in the same location.

Published Dec. 23 in Nature, the findings suggest that our brains generate a common code to mark where other people are in relation to ourselves.

"We studied how our brain reacts when we navigate a physical space -- first alone and then with others," said senior author Nanthia Suthana, the Ruth and Raymond Stotter Chair in Neurosurgery and an assistant professor of neurosurgery and psychiatry at the David Geffen School of Medicine at UCLA and Jane and Terry Semel Institute for Neuroscience and Human Behavior.

"Our results imply that our brains create a universal signature to put ourselves in someone else's shoes," added Suthana, whose laboratory studies how the brain forms and recalls memories.

Suthana and her colleagues observed epilepsy patients whose brains had been surgically implanted earlier with electrodes to control their seizures. The electrodes resided in the medial temporal lobe, the brain center linked to memory and suspected to regulate navigation, much like a GPS device.

"Earlier studies have shown that low-frequency brain waves by neurons in the medial temporal lobe help rodents keep track of where they are as they navigate a new place," said first author Matthias Stangl, a postdoctoral scholar in Suthana's lab. "We wanted to investigate this idea in people -- and test whether they could also monitor others near them -- but were hampered by existing technology."

Using a $3.3 million award from the National Institutes of Health's BRAIN Initiative, Suthana's lab invented a special backpack containing a computer that wirelessly connects to brain electrodes. This enabled her to study research subjects as they moved freely instead of lying still in a brain scanner or hooked up to a recording device.

In this experiment, each patient wore the backpack and was instructed to explore an empty room, find a hidden spot and remember it for future searches. While they walked, the backpack recorded their brain waves, eye movements and paths through the room in real time.

As the participants searched the room, their brain waves flowed in a distinctive pattern, suggesting that each person's brain had mapped out the walls and other boundaries. Interestingly, the patients' brain waves also flowed in a similar manner when they sat in a corner of the room and watched someone else approach the location of the hidden spot.

The finding implies that our brains produce the same pattern to track where we and other people are in a shared environment.

Why is this important?

"Everyday activities require us to constantly navigate around other people in the same place," said Suthana, who is also an assistant professor of psychology at UCLA's College of Letters and Science and of bioengineering at the Henry Samueli School of Engineering. "Consider choosing the shortest airport security line, searching for a space in a crowded parking lot or avoiding bumping into someone on the dance floor."

In a secondary finding, the UCLA team discovered that what we pay attention to may influence how our brains map out a location. For example, the patients' brain waves flowed stronger when they searched for the hidden spot -- or witnessed another person approach the location -- than when they simply explored the room.

"Our results support the idea that, under certain mental states, this pattern of brain waves may help us recognize boundaries," said Stangl. "In this case, it was when people were focused on a goal and hunting for something."

Future studies will explore how people's brain patterns react in more complex social situations, including outside the laboratory. The UCLA team has made the backpack available to other researchers to accelerate discoveries about the brain and brain disorders.

The aroma of distant worlds

Spices

Asian spices such as turmeric and fruits like the banana had already reached the Mediterranean more than 3000 years ago, much earlier than previously thought. A team of researchers working alongside archaeologist Philipp Stockhammer at Ludwig-Maximilians-Universität in Munich (LMU) has shown that even in the Bronze Age, long-distance trade in food was already connecting distant societies.

A market in the city of Megiddo in the Levant 3700 years ago: The market traders are hawking not only wheat, millet or dates, which grow throughout the region, but also carafes of sesame oil and bowls of a bright yellow spice that has recently appeared among their wares. This is how Philipp Stockhammer imagines the bustle of the Bronze Age market in the eastern Mediterranean. Working with an international team to analyze food residues in tooth tartar, the LMU archaeologist has found evidence that people in the Levant were already eating turmeric, bananas and even soy in the Bronze and Early Iron Ages. "Exotic spices, fruits and oils from Asia had thus reached the Mediterranean several centuries, in some cases even millennia, earlier than had been previously thought," says Stockhammer. "This is the earliest direct evidence to date of turmeric, banana and soy outside of South and East Asia." It is also direct evidence that as early as the second millennium BCE there was already a flourishing long-distance trade in exotic fruits, spices and oils, which is believed to have connected South Asia and the Levant via Mesopotamia or Egypt. While substantial trade across these regions is amply documented later on, tracing the roots of this nascent globalization has proved to be a stubborn problem. The findings of this study confirm that long-distance trade in culinary goods has connected these distant societies since at least the Bronze Age. People obviously had a great interest in exotic foods from very early on.

For their analyses, Stockhammer's international team examined 16 individuals from the Megiddo and Tel Erani excavations, which are located in present-day Israel. The region in the southern Levant served as an important bridge between the Mediterranean, Asia and Egypt in the 2nd millennium BCE. The aim of the research was to investigate the cuisines of Bronze Age Levantine populations by analyzing traces of food remnants, including ancient proteins and plant microfossils, that have remained preserved in human dental calculus over thousands of years.

The human mouth is full of bacteria, which continually petrify and form calculus. Tiny food particles become entrapped and preserved in the growing calculus, and it is these minute remnants that can now be accessed for scientific research thanks to cutting-edge methods. For the purposes of their analysis, the researchers took samples from a variety of individuals at the Bronze Age site of Megiddo and the Early Iron Age site of Tel Erani. They analyzed which food proteins and plant residues were preserved in the calculus on their teeth. "This enables us to find traces of what a person ate," says Stockhammer. "Anyone who does not practice good dental hygiene will still be telling us archaeologists what they have been eating thousands of years from now!"

Palaeoproteomics is the name of this growing new field of research. The method could develop into a standard procedure in archaeology, or so the researchers hope. "Our high-resolution study of ancient proteins and plant residues from human dental calculus is the first of its kind to study the cuisines of the ancient Near East," says Christina Warinner, a molecular archaeologist at Harvard University and the Max Planck Institute for the Science of Human History and co-senior author of the article. "Our research demonstrates the great potential of these methods to detect foods that otherwise leave few archaeological traces. Dental calculus is such a valuable source of information about the lives of ancient peoples."

"Our approach breaks new scientific ground," explains LMU biochemist and lead author Ashley Scott. That is because assigning individual protein remnants to specific foodstuffs is no small task. Beyond the painstaking work of identification, the protein itself must also survive for thousands of years. "Interestingly, we find that allergy-associated proteins appear to be the most stable in human calculus," says Scott, a finding she believes may be due to the known thermostability of many allergens. For instance, the researchers were able to detect wheat via wheat gluten proteins, says Stockhammer. The team was then able to independently confirm the presence of wheat using a type of plant microfossil known as phytoliths. Phytoliths were also used to identify millet and date palm in the Levant during the Bronze and Iron Ages, but phytoliths are not abundant or even present in many foods, which is why the new protein findings are so groundbreaking -- paleoproteomics enables the identification of foods that have left few other traces, such as sesame. Sesame proteins were identified in dental calculus from both Megiddo and Tel Erani. "This suggests that sesame had become a staple food in the Levant by the 2nd millennium BCE," says Stockhammer.

Two additional protein findings are particularly remarkable, explains Stockhammer. In one individual's dental calculus from Megiddo, turmeric and soy proteins were found, while in another individual from Tel Erani banana proteins were identified. All three foods are likely to have reached the Levant via South Asia. Bananas were originally domesticated in Southeast Asia, where they had been used since the 5th millennium BCE, and they arrived in West Africa 4000 years later, but little is known about their intervening trade or use. "Our analyses thus provide crucial information on the spread of the banana around the world. No archaeological or written evidence had previously suggested such an early spread into the Mediterranean region," says Stockhammer, although the sudden appearance of banana in West Africa just a few centuries later has hinted that such a trade might have existed. "I find it spectacular that food was exchanged over long distances at such an early point in history."

Stockhammer notes that they cannot rule out the possibility, of course, that one of the individuals spent part of their life in South Asia and consumed the corresponding food only while they were there. Even if the extent to which spices, oils and fruits were imported is not yet known, there is much to indicate that trade was indeed taking place, since there is also other evidence of exotic spices in the Eastern Mediterranean -- Pharaoh Ramses II was buried with peppercorns from India in 1213 BCE. They were found in his nose.

Meteoric evidence for a previously unknown asteroid

Ceres dwarf planet illustration 

 A Southwest Research Institute-led team of scientists has identified a potentially new meteorite parent asteroid by studying a small shard of a meteorite that arrived on Earth a dozen years ago. The composition of a piece of the meteorite Almahata Sitta (AhS) indicates that its parent body was an asteroid roughly the size of Ceres, the largest object in the main asteroid belt, and formed in the presence of water under intermediate temperatures and pressures.

"Carbonaceous chondrite (CC) meteorites record the geological activity during the earliest stages of the Solar System and provide insight into their parent bodies' histories," said SwRI Staff Scientist Dr. Vicky Hamilton, first author of a paper published in Nature Astronomy outlining this research. "Some of these meteorites are dominated by minerals providing evidence for exposure to water at low temperatures and pressures. The composition of other meteorites points to heating in the absence of water. Evidence for metamorphism in the presence of water at intermediate conditions has been virtually absent, until now."

Asteroids -- and the meteors and meteorites that sometimes come from them -- are leftovers from the formation of our Solar System 4.6 billion years ago. Most reside in the main asteroid belt between the orbits of Mars and Jupiter, but collisions and other events have broken them up and ejected remnants into the inner Solar System. In 2008, a 9-ton, 13-foot diameter asteroid entered Earth's atmosphere, exploding into some 600 meteorites over the Sudan. This marked the first time scientists predicted an asteroid impact prior to entry and allowed recovery of 23 pounds of samples.

"We were allocated a 50-milligram sample of AhS to study," Hamilton said. "We mounted and polished the tiny shard and used an infrared microscope to examine its composition. Spectral analysis identified a range of hydrated minerals, in particular amphibole, which points to intermediate temperatures and pressures and a prolonged period of aqueous alteration on a parent asteroid at least 400, and up to 1,100, miles in diameter."

Amphiboles are rare in CC meteorites, having only been identified previously as a trace component in the Allende meteorite. "AhS is a serendipitous source of information about early Solar System materials that are not represented by CC meteorites in our collections," Hamilton said.

Orbital spectroscopy of asteroids Ryugu and Bennu visited by Japan's Hayabusa2 and NASA's OSIRIS-REx spacecraft this year is consistent with aqueously altered CC meteorites and suggests that both asteroids differ from most known meteorites in terms of their hydration state and evidence for large-scale, low-temperature hydrothermal processes. These missions have collected samples from the surfaces of the asteroids for return to Earth.

"If the compositions of the Hayabusa2 and OSIRIS-REx samples differ from what we have in our collections of meteorites, it could mean that their physical properties cause them to fail to survive the processes of ejection, transit and entry through Earth's atmosphere, at least in their original geologic context," said Hamilton, who also serves on the OSIRIS-REx science team. "However, we think that there are more carbonaceous chondrite materials in the Solar System than are represented by our collections of meteorites."