Loneliness doesn’t just make people feel isolated. It alters their brain in ways that can hinder their ability to trust and connect to others. In The Neumayer III polar station sits near the edge of Antarctica’s unforgiving Ekström Ice Shelf during the winter, when temperatures can plunge below minus 50 degrees Celsius and the winds can climb to more than 100 kilometers per hour, no one can come or go from the station.
Its isolation is essential to the meteorological, atmospheric and geophysical science experiments conducted there by the mere handful of scientists who staff the station during the winter months and endure its frigid loneliness.
But a few years ago, the station also became the site for a study of loneliness itself. A team of scientists in Germany wanted to see whether the social isolation and environmental monotony marked the brains of people making long Antarctic stays.
Eight expeditioners working at the Neumayer III station for 14 months agreed to have their brains scanned before and after their mission and to have their brain chemistry and cognitive performance monitored during their stay. (A ninth crew member also participated but could not have their brain scanned for medical reasons.)
As the researchers described in 2019, in comparison to a control group, the socially isolated team lost volume in their prefrontal cortex — the region at the front of the brain, just behind the forehead, that is chiefly responsible for decision-making and problem-solving.
They also had lower levels of brain-derived neurotrophic factor, a protein that nurtures the development and survival of nerve cells in the brain. The reduction persisted for at least a month and a half after the team’s return from Antarctica.
It’s uncertain how much of this was due purely to the social isolation of the experience. But the results are consistent with evidence from more recent studies that chronic loneliness significantly alters the brain in ways that only worsen the problem.
Neuroscience suggests that loneliness doesn’t necessarily result from a lack of opportunity to meet others or a fear of social interactions. Instead, circuits in our brain and changes in our behavior can trap us in a catch-22 situation: While we desire connection with others, we view them as unreliable, judgmental and unfriendly.
Consequently, we keep our distance, consciously or unconsciously spurning potential opportunities for connections. Loneliness can be difficult to study empirically because it is entirely subjective. Social isolation, a related condition, is different — it’s an objective measure of how few relationships a person has.
The experience of loneliness has to be self-reported, although researchers have developed tools such as the UCLA Loneliness Scale to help with assessing the depths of an individual’s feelings. From such work, it’s clear that the physical and psychological toll of loneliness across the globe is profound.
In one survey, 22% of Americans and 23% of British people said they felt lonely always or often. And that was before the pandemic. As of October 2020, 36% of Americans reported “serious loneliness.”
Organizations and governments often attempt to help with loneliness by encouraging people to go out more and by setting up hobby clubs, community gardens and craft groups. Yet as the neuroscience shows, getting rid of loneliness isn’t always that simple.
A Bias Toward Rejection
When neuroscientists from Germany and Israel set out to investigate loneliness a few years ago, they expected to find that its neural underpinnings were like those of social anxiety and involved the amygdala. Often called the fear center of the brain, the amygdala tends to activate when we face things we dread, from snakes to other humans.
“We thought, ‘Social anxiety is associated with increased amygdala activity, so this should also be the case for lonely individuals,’” said Jana Lieberz, a doctoral student at the University of Bonn in Germany who was part of the research team.
When Valentine’s Day arrives Tuesday, many people will show their love and affection with cards, chocolates and gifts, but there is another way to make your partner or family member feel good — through touch. Studies show that social touch is essential to our mental well-being and can reduce stress and pain while helping us bond with one another.
Physical isolation during the coronavirus pandemic led many to develop “skin hunger” and resulted in an uptick in mental health problems. One 2021 study surveying almost 1,500 participants reported that deprivation of intimate touch from close family and partners was associated with worse feelings of anxiety and loneliness.
Lack of friendly or professional touch from friends, acquaintances or work colleagues did not have the same impact on mental health.How we can feel social touch. Social touch is so important for our well-being that we have specific cells in our skin to detect it. Our skin gives us the power of discriminative touch, which allows us to feel the pressure, texture and vibration of objects.
But our skin also has sensors known as C-tactile fibers or afferents that are specifically sensitive to social touch from people and the caress of a loved one. C-tactile fibers innervate hairy skin and are optimized to detect the gentle stroking touch of 1 to 10 centimeters (half- to four inches) per second that many people say is pleasant. If the movement is too fast or too slow, not only are the C-tactile fibers less responsive but people also find the sensation less pleasing.
Interestingly, they are also more attuned to warmer temperatures of around 32 degrees Celsius (almost 90 degrees Fahrenheit), akin to the warmth of a person’s skin. There are individual differences, however, in the need and craving for social touch. “I think touch is very important,” said Mariana von Mohr, a researcher specializing in social cognition at Royal Holloway University of London.
“But at the same time, we have to be a bit careful about these individual differences because there are people that might prefer to connect in some other way.” But in general, intimate touch between loved ones is important for emotional regulation and social buffering, where being together with others helps us handle and recover from stress.
The benefits of social touch
Social touch causes the release of the social-bonding hormone oxytocin in the brain, which is thought to reduce anxiety and pain. Von Mohr’s research has found that romantic partners felt less pain when receiving a slow, stroking touch compared with a faster touch. Other studies have found that touch enhances intimacy between couples.
In one study, 84 adult women participated in an experiment showcasing the soothing power of affective touch on feelings of social exclusion. Each participant played Cyberball, an online ball-tossing game, with two other players who, unbeknown to the subjects, were bots that would eventually stop throwing the virtual ball to the participant.
When that happens, it can produce a profound sense of social exclusion, and even led to “one participant actually smashing the computer,” von Mohr said. But when half of the participants received a slow, affective touch from the experimenter afterward, their feelings of social exclusion were partially mitigated. The other half of participants who received a fast-stroking touch, which would not activate C-tactile fibers, did not experience similar relief.
This is akin to a mother comforting a child after a similar experience of social hurt, von Mohr said. “We do this sometimes without realizing how good it is,” she said. All mammals that have been studied have C-tactile fibers, suggesting that these sensory cells — and the ability to detect social touch — are evolutionarily conserved and essential, said Ishmail Abdus-Saboor, a biological scientist specializing in touch research at Columbia University’s Zuckerman Mind Brain Behavior Institute.
From skin to brain for pleasurable social touch
Research suggests that social-touch-sensitive neurons may be key for making the touch of a loved one feel good, which in turn helps bind us. A study in Cell this month found that directly stimulating neurons in female mice — similar to C-tactile fibers in humans — can release dopamine, a neurochemical associated with reward, in their brains. These Mrgprb4 neurons are also necessary for female mice to be receptive to sexual advances from male mice.
Using optogenetics, a now-mainstay neuroscience technique that allows researchers to manipulate the activities of specific neurons by shining a light on them, researchers activated the Mrgprb4 sensory cells on the back, an important area for social touch in mice where they groom and huddle together. The researchers saw that the female mice would lower their backs in response to the light, which is lordosis, a female mouse sexual behavior indicating receptivity to a male mouse.
The finding that activating cells in the skin can trigger a “social touch-like behavior even without other sensory cues” such as the presence of another mouse “was pretty surprising,” said Abdus-Saboor, who was an author of the new study. Stimulating Mrgprb4 neurons was pleasurable, and female mice spent more time in designated sections of the cage where researchers activated the cells.
Intriguingly, stimulating these sensory neurons and engaging in sexual behavior both released dopamine in the nucleus accumbens, a key brain area associated with reward. But when the researchers genetically ablated these Mrgprb4 sensory neurons, sexual experiences no longer released dopamine and the female mice began rejecting the male mice’s advances after their first experience.
The male mouse’s touch was no longer rewarding, and the male’s advances were no longer welcome. The female mouse would even become combative with her paws up, making herself inaccessible to the male. “I sometimes think she throws a punch,” said Leah Elias, a postdoctoral researcher at Johns Hopkins University who conducted the study as a graduate student at the University of Pennsylvania.
Though this study examined the importance of pleasurable touch to sexual behaviors in mice, the researchers say the Mrgprb4 cells also play a role in other forms of affiliative social touch such as play. Before the touch signals reach the brain, “even at the first relay station in the skin, there are already dedicated cells that are competent to engage social stimuli,” Abdus-Saboor said. Their research opens up a potential target for future therapeutics that can use the skin to access reward circuits to help treat trauma or depression.
“Just by activating these neurons in the skin, you kind of have a highway to the brain,” Elias said. “It’s kind of a gold mine.”With just a hug, a caress or a gentle squeeze of the hand, we can already take advantage of the power of social touch. To feel better, healthier and more connected, skin deep is a good place to start.
In 1903, TheNew York Times predicted it would take between 1 million and 10 million years to develop airplanes. The Wright Brothers took flight just nine weeks later. In 2023, the same levels of ambition, determination, and innovation will make green flight a reality, and the first commercial passenger planes fueled by hydrogen will take to the skies.
Aviation is the world’s fastest-growing contributor to climate change. According to a report by the International Coalition for Sustainable Aviation, by 2037 we will see an estimated doubling of air passengers to 8.2 billion. And by 2050, the sector could be responsible for as much as 22 percent of our total carbon emissions. We know that we have to cut global emissions in half by 2030—and that means addressing the rising contribution of the aviation sector, and quickly.
My company, ZeroAvia, is tackling the transition to zero-emission aviation through the development of hydrogen-electric engines for airplanes. These use hydrogen in fuel cells to generate electricity, which is then used to power electric motors to turn the aircraft’s propellers. Ultimately, we will put these engines in every type of aircraft—all the way up to large, commercial aircraft.
Why fuel cells? According to McKinsey, electric flight powered by hydrogen offers the best possible reduction in climate impact. Hydrogen fuel cells are between two and three times more energy efficient than current gas-guzzling fuel combustion engines. And the sole byproduct from these engines is water.
Alternatives, such as sustainable aviation fuel, do not tackle the problem of non-carbon emissions. Nitrogen oxides, particulates, soot, and high-temperature water vapor are all potent climate forcing agents. Combined, these have a larger climate change impact than carbon dioxide does alone. But for hydrogen-electric engines, they do not enter the equation.
What about batteries? Too heavy and too inefficient. Research from the University of Houston suggests eight airplanes would be required to carry the batteries needed to power a jumbo jet. What works for a Tesla doesn’t necessarily work for a Dreamliner.
Hydrogen is also abundant—as it can be produced from water—and it will only become cheaper to produce. According to PWC, the cost of green hydrogen will drop by 50 percent by 2030. On-site hydrogen production further lowers prices and makes the entire system zero-emission from end to end.
In 2023, we will finalize the design for the world’s first commercial hydrogen-electric aircraft engine, and we plan to enter the market by the following year. This will unlock commercial zero-emission flights of up to 300 miles, say, London to Glasgow, or San Francisco to Los Angeles. As well as powering new aircraft, hydrogen-electric engines can also be retro-fitted into existing planes, ensuring rapid market entry and enabling us to tackle the sector’s emissions sooner.
While converting the entire industry will take time, the road map is obvious. The UK’s Aerospace Technology Institute’s FlyZero project made it clear that hydrogen will be aviation’s fuel of the future. This year-long independent study commissioned by the UK government established that the first generation of zero-emission aircraft would need to include hydrogen technology by 2025.
The world’s biggest problem requires the farthest-reaching solutions, and support for hydrogen is growing in governments globally. Measures in the US Inflation Reduction Act will turbocharge the hydrogen economy, while the UK’s Jet Zero strategy aims to deliver net-zero aviation by the middle of the century. In 2023, accelerating innovation will meet this increasing political will, and hydrogen electricity will start the process of transforming aviation into a zero-emissions industry in a generation.
You may know that being adequately hydrated is important for day-to-day bodily functions such as regulating temperature and maintaining skin health. But drinking enough water is also associated with a significantly lower risk of developing chronic diseases, a lower risk of dying early or lower risk of being biologically older than your chronological age, according to a National Institutes of Health study published Monday in the journal eBioMedicine.
“The results suggest that proper hydration may slow down aging and prolong a disease-free life,” said study author Natalia Dmitrieva, a researcher in the Laboratory of Cardiovascular Regenerative Medicine at the National Heart, Lung and Blood Institute, a division of NIH, in a news release.
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Learning what preventive measures can slow down the aging process is “a major challenge of preventive medicine,” the authors said in the study. That’s because an epidemic of “age-dependent chronic diseases” is emerging as the world’s population rapidly ages. And extending a healthy life span can help improve quality of life and decrease health care costs more than just treating diseases can.
The authors thought optimal hydration might slow down the aging process, based on previous similar research in mice. In those studies, lifelong water restriction increased the serum sodium of mice by 5 millimoles per liter and shortened their life span by six months, which equals about 15 years of human life, according to the new study. Serum sodium can be measured in the blood and increases when we drink less fluids.
Using health data collected over 30 years from 11,255 Black and White adults from the Atherosclerosis Risk in Communities study, or ARIC, the research team found adults with serum sodium levels at the higher end of the normal range — which is 135 to 146 milliequivalents per liter (mEq/L) — had worse health outcomes than those at the lower end of the range. Data collection began in 1987 when participants were in their 40s or 50s, and the average age of participants at the final assessment during the study period was 76.
Adults with levels above 142 mEq/L had a 10% to 15% higher chance of being biologically older than their chronological age compared with participants in the 137 to 142 mEq/L range. The participants with higher faster-aging risk also had a 64% higher risk for developing chronic diseases such as heart failure, stroke, atrial fibrillation, peripheral artery disease, chronic lung disease, diabetes and dementia.
And people with levels above 144 mEq/L had a 50% higher risk of being biologically older and a 21% higher risk of dying early. Adults with serum sodium levels between 138 and 140 mEq/L, on the other hand, had the lowest risk of developing chronic disease. The study didn’t have information on how much water participants drank.
“This study adds observational evidence that reinforces the potential long-term benefits of improved hydration on reductions in long-term health outcomes, including mortality,” said Dr. Howard Sesso, an associate professor of medicine at Harvard Medical School and associate epidemiologist at Brigham and Women’s Hospital in Boston, via email. Sesso was not involved in the study.
However, “it would have been nice to combine their definition of hydration, based on serum sodium levels only, with actual fluid intake data from the ARIC cohort,” Sesso added.
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Biological age was determined by biomarkers that measure the performance of different organ systems and processes, including cardiovascular, renal (relating to the kidneys), respiratory, metabolic, immune and inflammatory biomarkers.
High serum sodium levels weren’t the only factor associated with disease, early death and faster aging risk — risk was also higher among people with low serum sodium levels. This finding is consistent with previous reports of increased mortality and cardiovascular disease in people with low regular sodium levels, which has been attributed to diseases causing electrolyte issues, the authors said.
The study analyzed participants over a long period of time, but the findings don’t prove a causal relationship between serum sodium levels and these health outcomes, the authors said. Further studies are needed, they added, but the findings can help doctors identify and guide patients at risk.
“People whose serum sodium is 142 mEq/L or higher would benefit from evaluation of their fluid intake,” Dmitrieva said. Sesso noted that the study did not strongly address accelerated aging, “which is a complicated concept that we are just starting to understand.”
“Two key reasons underlie this,” Sesso said. The study authors “relied on a combination of 15 measures for accelerated aging, but this is one of many definitions out there for which there is no consensus. Second, their data on hydration and accelerated aging were a ‘snapshot’ in time, so we have no way to understand cause and effect.”
Drink enough fluids every day
About half of people worldwide don’t meet recommendations for daily total water intake, according to several studies the authors of the new research cited.
“On the global level, this can have a big impact,” Dmitrieva said in a news release. “Decreased body water content is the most common factor that increases serum sodium, which is why the results suggest that staying well hydrated may slow down the aging process and prevent or delay chronic disease.”
Our serum sodium levels are influenced by liquid intake from water, other liquids, and fruits and vegetables with high water content.
“The most impressive finding is that this risk (for chronic diseases and aging) is apparent even in individuals who have serum sodium levels that are on the upper end of the ‘normal range,’” said Dr. Richard Johnson, professor at the University of Colorado School of Medicine, via email. He was not involved in the study.
“This challenges the question of what is really normal, and supports the concept that as a population we are probably not drinking enough water.”
More than 50% of your body is made of water, which is also needed for multiple functions, including digesting food, creating hormones and neurotransmitters, and delivering oxygen throughout your body, according to the Cleveland Clinic.
The National Academy of Medicine (formerly known as the Institute of Medicine) recommends women consume 2.7 liters (91 ounces) of fluids daily, and that men have 3.7 liters (125 ounces) daily. This recommendation includes all fluids and water-rich foods such as fruits, vegetables and soups. Since the average water intake ratio of fluids to foods is around 80:20, that amounts to a daily amount of 9 cups for women and 12 ½ cups for men.
People with health conditions should talk with their doctor about how much fluid intake is right for them.
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“The goal is to ensure patients are taking in enough fluids, while assessing factors, like medications, that may lead to fluid loss,” said study coauthor Dr. Manfred Boehm, director of the Laboratory of Cardiovascular Regenerative Medicine, in a news release. “Doctors may also need to defer to a patient’s current treatment plan, such as limiting fluid intake for heart failure.”
If you’re having trouble staying hydrated, you might need help working the habit into your usual routine. Try leaving a glass of water at your bedside to drink when you wake up, or drink water while your morning coffee is brewing. Anchor your hydration habit to a location you’re in a few times per day, behavioral science expert Dr. B.J. Fogg, founder and director of the Stanford University Behavior Design Lab, previously told CNN.
A new study in Nature Sustainability incorporates the damages that climate change does to healthy ecosystems into standard climate-economics models. The key finding in the study by Bernardo Bastien-Olvera and Frances Moore from the University of California at Davis:
The models have been underestimating the cost of climate damages to society by a factor of more than five. Their study concludes that the most cost-effective emissions pathway results in just 1.5 degrees Celsius (2.7 degrees Fahrenheit) additional global warming by 2100, consistent with the “aspirational” objective of the 2015 Paris Climate Agreement.
Models that combine climate science and economics, called “integrated assessment models” (IAMs), are critical tools in developing and implementing climate policies and regulations.
In 2010, an Obama administration governmental interagency working group used IAMs to establish the social cost of carbon – the first federal estimates of climate damage costs caused by carbon pollution. That number guides federal agencies required to consider the costs and benefits of proposed regulations.
Economic models of climate have long been criticized by those convinced they underestimate the costs of climate damages, in some cases to a degree that climate scientists consider absurd. Given the importance of the social cost of carbon to federal rulemaking, some critics have complained that the Trump EPA used what they see as creative accounting to slash the government’s estimate of the number. In one of his inauguration day Executive Orders, President Biden established a new Interagency Working Group to re-evaluate the social cost of all greenhouse gases.
IAMs often have long been criticized by those convinced they underestimate the costs of climate damages, in some cases to a degree that climate scientists consider absurd. Perhaps the most prominent IAM is the Dynamic Integrated Climate-Economy (DICE) model, for which its creator, William Nordhaus, was awarded the 2018 Nobel Prize in Economic Sciences.
Judging by DICE, the economically optimal carbon emissions pathway – that is, the pathway considered most cost-effective – would lead to a warming increase of more than 3°C (5.4°F) from pre-industrial temperatures by 2100 (under a 3% discount rate). IPCC has reported that reaching this level of further warming could likely result in severe consequences, including substantial species extinctions and very high risks of food supply instabilities.
In their Nature Sustainability study, the UC Davis researchers find that when natural capital is incorporated into the models, the emissions pathway that yields the best outcome for the global economy is more consistent with the dangerous risks posed by continued global warming described in the published climate science literature.
Accounting for climate change degrading of natural capital
Natural capital includes elements of nature that produce value to people either directly or indirectly. “DICE models economic production as a function of generic capital and labor,” Moore explained via email. “If instead you think natural capital plays some distinct role in economic production, and that climate change will disproportionately affect natural capital, then the economic implications are much larger than if you just roll everything together and allow damage to affect output.”
Bastien-Olvera offered an analogy to explain the incorporation of natural capital into the models: “The standard approach looks at how climate change is damaging ‘the fruit of the tree’ (market goods); we are looking at how climate change is damaging the ‘tree’ itself (natural capital).” In an adaptation of DICE they call “GreenDICE,” the authors incorporated climate impacts on natural capital via three pathways:
The first pathway accounts for the direct influence of natural capital on market goods. Some industries like timber, agriculture, and fisheries are heavily dependent on natural capital, but all goods produced in the economy rely on these natural resources to some degree.
According to GreenDICE, this pathway alone more than doubles the model’s central estimate of the social cost of carbon in 2020 from $28 per ton in the standard DICE model to $72 per ton, and the new economically optimal pathway would have society limit global warming to 2.2°C (4°F) above pre-industrial temperatures by 2100.
The second pathway incorporates ecosystem services that don’t directly feed into market goods. Examples are the flood protection provided by a healthy mangrove forest, or the recreational benefits provided by natural places.
In the study, this second pathway nearly doubles the social cost of carbon once again, to $133 per ton in 2020, and it lowers the most cost-effective pathway to 1.8°C (3.2°F) by 2100. Finally, the third pathway includes non-use values, which incorporate the value people place on species or natural places, regardless of any good they produce. The most difficult to quantify, this pathway could be measured, for instance, by asking people how much they would be willing to pay to save one of these species from extinction.
In GreenDICE, non-use values increase the social cost of carbon to $160 per ton of carbon dioxide in 2020 (rising to about $300 in 2050 and $670 per ton in 2100) and limit global warming to about 1.5°C (2.8°F) by 2100 in the new economically optimal emissions pathway. (Note for economics wonks – the model runs used a 1.5% pure rate of time preference.)
Climate economics findings increasingly reinforce Paris targets
It may come as no surprise that destabilizing Earth’s climate would be a costly proposition, but key IAMs have suggested otherwise. Based on the new Nature Sustainability study, the models have been missing the substantial value of natural capital associated with healthy ecosystems that are being degraded by climate change.
Columbia University economist Noah Kaufman, not involved in the study, noted via email that as long as federal agencies use the social cost of carbon in IAMs for rulemaking cost-benefit analyses, efforts like GreenDICE are important to improving those estimates. According to Kaufman, many papers (including one he authored a decade ago) have tried to improve IAMs by following a similar recipe: “start with DICE => find an important problem => improve the methodology => produce a (usually much higher) social cost of carbon.”
For example, several other papers published in recent years, including one authored by Moore, have suggested that, because they neglect ways that climate change will slow economic growth, IAMs may also be significantly underestimating climate damage costs. Poorer countries – often located in already-hot climates near the equator, with economies relying most heavily on natural capital, and lacking resources to adapt to climate change – are the most vulnerable to its damages, despite their being the least responsible for the carbon pollution causing the climate crisis.
Another recent study in Nature Climate Change updated the climate science and economics assumptions in DICE and similarly concluded that the most cost-effective emissions pathway would limit global warming to less than 2°C (3.6°F) by 2100, without even including the value of natural capital. Asked about that paper, Bastien-Olvera noted, “In my view, the fact that these two studies get to similar policy conclusions using two very different approaches definitely indicates the urgency of cutting emissions.”
Recent economics and climate science research findings consistently support more aggressive carbon emissions efforts consistent with the Paris climate targets.
Wesleyan University economist Gary Yohe, also not involved in the study, agreed that the new Nature Sustainability study “supports growing calls for aggressive near-term mitigation.” Yohe said the paper “provides added support to the notion that climate risks to natural capital are important considerations, especially in calibrating the climate risk impacts of all sorts of regulations like CAFE standards.”
But Yohe said he believes that considering the risks to unique and threatened systems at higher temperatures makes a more persuasive case for climate policy than just attempting to assess their economic impacts. In a recent Nature Climate Change paper, Kaufman and colleagues similarly suggested that policymakers should select a net-zero emissions target informed by the best available science and economics, and then use models to set a carbon price that would achieve those goals.
Their study estimated that to reach net-zero carbon pollution by 2050, the U.S. should set a carbon price of about $50 per ton in 2025, rising to $100 per ton by 2030. However climate damages are evaluated, whether through a more complete economic accounting of adverse impacts or via risk-based assessments of physical threats to ecological and human systems, recent economics and climate science research findings consistently support more aggressive carbon emissions efforts consistent with the Paris climate targets.
Kouzou Sakai for Quanta Magazine
